Powered by Deep Web Technologies
Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Polyneutron Chain Reactions  

SciTech Connect (OSTI)

Although helium atoms do not form molecules, a sufficiently large number will bind into a stable liquid droplet. A comparable situation is expected for neutrons, with a sufficiently large number binding into a stable droplet of neutron matter. Such polyneutron droplets can be viewed as isotopes of an element with nuclear charge Z=0, tentatively denoted neutrium, symbol Nt. Because of the relatively weak binding of neutrons compared with that of a mix of neutrons and protons, the minimum number of neutrons required for stability of a droplet is fairly large. Early estimates of {approx}60 may be reduced to a dozen or so by the BCS pairing interaction. The Nt entries with N{>=}12 are new to the table of isotopes. Because all of them are beta-unstable, none is expected to persist as a free particle. Yet, some may occasionally be produced by means to be described below, and it is of interest to examine their decay chains and their interactions with charged nuclei to ascertain how their presence might be revealed. Although these reactions are interesting, they cannot be taken seriously without identifying a source for the initial Nt isotope that begins the chain. Here, we consider possible interactions between {sup 16}O and {sup A}Nt. Although there is no strong interaction between them, we can expect a very weak residual attraction that can form a loosely bound {sup 16}O {sup A}Nt nuclear molecule. This is not a compound nucleus in the usual sense because, considered as fluids, the {sup 16}O and {sup A}Nt droplets are immiscible. For a droplet with fewer than about 60 neutrons, beta decay of {sup A}Nt is prevented by the buildup of Coulomb energy associated with transforming {sup A}Nt into {sup A}H in close proximity to {sup 16}O. Thus, it is possible that {sup 16}O {sup A}Nt molecules can persist indefinitely and that a few of them may be present in ordinary water as supermassive oxygen nuclei. Because the binding of these molecules is weak, the {sup A}Nt component can tunnel to an adjacent nucleus, and if the adjacent nucleus is {sup 18}O, a chain reaction can begin. The circumstances under which it can develop to produce macroscopic consequences depend on the mix of reactants and upon the appropriate removal of poisons and addition of fresh reactants to the reaction volume. With the proper conditions, there can be generation of sensible excess energy, helium, and other reaction products associated with the various cold fusion reactions.

John C. Fisher

2000-11-12T23:59:59.000Z

2

Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48 + Am-243  

E-Print Network [OSTI]

Products of the fusion-evaporation reaction Ca-48 + Am-243 were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum f\\"ur Schwerionenforschung. Amongst the detected thirty correlated alpha-decay chains associated with the production of element Z=115, two recoil-alpha-fission and five recoil-alpha-alpha-fission events were observed. The latter are similar to four such events reported from experiments performed at the Dubna gas-filled separator. Contrary to their interpretation, we propose an alternative view, namely to assign eight of these eleven decay chains of recoil-alpha(-alpha)-fission type to start from the 3n-evaporation channel 115-288. The other three decay chains remain viable candidates for the 2n-evaporation channel 115-289.

U. Forsberg; D. Rudolph; L. -L. Andersson; A. Di Nitto; Ch. E. Düllmann; J. M. Gates; P. Golubev; K. E. Gregorich; C. J. Gross; R. -D. Herzberg; F. P. Hessberger; J. Khuyagbaatar; J. V. Kratz; K. Rykaczewski; L. G. Sarmiento; M. Schädel; A. Yakushev; S. Åberg; D. Ackermann; M. Block; H. Brand; B. G. Carlsson; D. Cox; X. Derkx; J. Dobaczewski; K. Eberhardt; J. Even; C. Fahlander; J. Gerl; E. Jäger; B. Kindler; J. Krier; I. Kojouharov; N. Kurz; B. Lommel; A. Mistry; C. Mokry; W. Nazarewicz; H. Nitsche; J. P. Omtvedt; P. Papadakis; I. Ragnarsson; J. Runke; H. Schaffner; B. Schausten; Y. Shi; P. Thörle-Pospiech; T. Torres; T. Traut; N. Trautmann; A. Türler; A. Ward; D. E. Ward; N. Wiehl

2015-02-10T23:59:59.000Z

3

Fission and quasi-fission: insights into heavy element formation reactions  

SciTech Connect (OSTI)

Mass-angle distributions carry detailed information on the characteristics of quasi-fission, and thus of the dynamics of heavy element formation reactions. Recent experimental results are presented and discussed.

Hinde, D. J.; Rietz, R. du; Rafiei, R.; Dasgupta, M.; Diaz-Torres, A. [Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Thomas, R. G. [Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); B.A.R.C., Mumbai (India)

2009-03-04T23:59:59.000Z

4

Fusion-fission reactions with modified Woods-Saxon potential  

E-Print Network [OSTI]

A modified Woods-Saxon potential model is proposed for a unified description of the entrance channel fusion barrier and the fission barrier of fusion-fission reactions based on the Skyrme energy-density functional approach. The fusion excitation functions of 120 reactions have been systematically studied. The fusion (capture) cross sections are well described with the calculated potential and an empirical barrier distribution. Incorporating a statistical model (HIVAP code) for describing the decay of the compound nucleus, the evaporation residue (and fission) cross sections of 51 fusion-fission reactions have been systematically investigated. Optimal values of some key parameters of the HIVAP code are obtained based on the experimental data of these reactions. The experimental data are reasonably well reproduced by the calculated results. The upper and lower confidence limits of the systematic errors of the calculated results are given.

Ning Wang; Kai Zhao; Werner Scheid; Xizhen Wu

2007-12-15T23:59:59.000Z

5

Nukes (notes on PFFP) Chain reactions  

E-Print Network [OSTI]

axis #12;Moore's Law data for memory and CPU #12;Back to Nuclear Physics The first selfNukes (notes on PFFP) Chain reactions: Must understand power laws and exponential growth "One grain = 8, 2 x 2 x 2 x 2 =16.....210=1024, ......264~1019 Will discuss and compare some aspects of nuclear

Browder, Tom

6

Electrochemical Branched-DNA Assay for Polymerase Chain Reaction...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Branched-DNA Assay for Polymerase Chain Reaction-Free Detection and Quantification of Oncogenes in Messenger RNA Electrochemical Branched-DNA Assay for Polymerase Chain...

7

Dual phase multiplex polymerase chain reaction  

DOE Patents [OSTI]

Highly specific and sensitive methods were developed for multiplex amplification of nucleic acids on supports such as microarrays. Based on a specific primer design, methods include five types of amplification that proceed in a reaction chamber simultaneously. These relate to four types of multiplex amplification of a target DNA on a solid support, directed by forward and reverse complex primers immobilized to the support and a fifth type--pseudo-monoplex polymerase chain reaction (PCR) of multiple targets in solution, directed by a single pair of unbound universal primers. The addition of the universal primers in the reaction mixture increases the yield over the traditional "bridge" amplification on a solid support by approximately ten times. Methods that provide multitarget amplification and detection of as little as 0.45-4.5.times.10.sup.-12 g (equivalent to 10.sup.2-10.sup.3 genomes) of a bacterial genomic DNA are disclosed.

Pemov, Alexander (Charlottesville, VA); Bavykin, Sergei (Darien, IL)

2008-10-07T23:59:59.000Z

8

Integrated polymerase chain reaction/electrophoresis instrument  

DOE Patents [OSTI]

A new approach and instrument for field identification of micro-organisms and DNA fragments using a small and disposable device containing integrated polymerase chain reaction (PCR) enzymatic reaction wells, attached capillary electrophoresis (CE) channels, detectors, and read-out all on/in a small hand-held package. The analysis instrument may be made inexpensively, for example, of plastic, and thus is disposable, which minimizes cross contamination and the potential for false positive identification between samples. In addition, it is designed for multiple users with individual applications. The integrated PCR/CE is manufactured by the PCR well and CE channels are "stamped" into plastic depressions where conductive coatings are made in the wells and ends of the CE microchannels to carry voltage and current to heat the PCR reaction mixtures and simultaneously draw DNA bands up the CE channels. Light is transmitted through the instrument at appropriate points and detects PCR bands and identifies DNA fragments by size (retention time) and quantifies each by the amount of light generated as each phototransistor positioned below each CE channel detects a passing band. The instrument is so compact that at least 100 PCR/CE reactions/analyses can be performed easily on one detection device.

Andresen, Brian D. (Livermore, CA)

2000-01-01T23:59:59.000Z

9

Fission product chain yields and delayed neutrons: ANS standards 5. 2 and 5. 8  

SciTech Connect (OSTI)

Chain yields are the addition of the direct values along constant (Z + N) paths. The addition must also account for decay branching, especially for delayed neutrons that couple the mass chains. The result is the familiar double-humped plot of yield per fission versus mass number. The lines of stable nuclides and most probable yield are shown in the (Z,N) plane. Some modern measurements provide direct yields; other provide cumulative values for long-lived or stable products. Yield evaluations must account for each type of measurement and the degree of decay coupling, beginning with direct yields. For some fissioning nuclides at thermal or fast neutron incident energies, the amount of data is enormous; and for other nuclide-energy combinations, the data must be developed from systematics. Many applications of chain yields can use the same systematics to estimate independent values. The ANS 5.2 standard is currently in rough draft form for comment from working group members.

England, T.R. (Los Alamos National Lab., NM (United States)); Brady, M.C. (Oak Ridge National Lab., TN (United States)); Rider, B.F.

1990-01-01T23:59:59.000Z

10

Lesson 5 - Fission and Chain Reactions | Department of Energy  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:Year in3.pdfEnergy Health andofIanJenniferLeslie Pezzullo: ... Biomass Program Webinar3 -5 -

11

Interplay between compound and fragments aspects of nuclear fission and heavy-ion reaction  

SciTech Connect (OSTI)

The scission point in nuclear fission plays a special role where one-body system changes to two-body system. Inverse of this situation is realized in heavy-ion fusion reaction where two-body system changes to one body system. Among several peculiar phenomena expected to occur during this change, we focus our attention to the behavior of compound and fragments shell effects. Some aspects of the interplay between compound and fragments shell effect are discussed related to the topics of the fission valleys in the potential energy surface of actinide nuclei and the fusion-like trajectory found in the cold fusion reaction leading to superheavy nuclei.

Moller, Peter [Los Alamos National Laboratory; Iwamoto, A [JAPAN; Ichikawa, I [JAPAN

2010-09-10T23:59:59.000Z

12

VII. Nuclear Chemistry (Chapter 17) A. Modes of radioactive decay, nuclear reactions, fission, fusion  

E-Print Network [OSTI]

40 VII. Nuclear Chemistry (Chapter 17) A. Modes of radioactive decay, nuclear reactions, fission #12;41 These masses are not exactly integer multiples due to nuclear interactions between the protons differences via the famous formula E = mc2 . Nuclear Fusion! For example, if you combine 2 protons and two

13

Evidence of microscopic effects in fragment mass distribution in heavy ion induced fusion-fission reactions  

E-Print Network [OSTI]

Our measurements of variances ($\\sigma_{m}^2$) in mass distributions of fission fragments from fusion-fission reactions of light projectiles (C, O and F) on deformed thorium targets exhibit a sharp anomalous increase with energy near the Coulomb barrier, in contrast to the smooth variation of $\\sigma_{m}^2$ for the spherical bismuth target. This departure from expectation based on a statistical description is explained in terms of microscopic effects arising from the orientational dependence in the case of deformed thorium targets.

T. K. Ghosh; S. Pal; K. S. Gold; P. Bhattacharya

2005-06-27T23:59:59.000Z

14

Fission-Fusion: A new reaction mechanism for nuclear astrophysics based on laser-ion acceleration  

SciTech Connect (OSTI)

We propose to produce neutron-rich nuclei in the range of the astrophysical r-process around the waiting point N = 126 by fissioning a dense laser-accelerated thorium ion bunch in a thorium target (covered by a CH{sub 2} layer), where the light fission fragments of the beam fuse with the light fission fragments of the target. Via the 'hole-boring' mode of laser Radiation Pressure Acceleration using a high-intensity, short pulse laser, very efficiently bunches of {sup 232}Th with solid-state density can be generated from a Th target and a deuterated CD{sub 2} foil, both forming the production target assembly. Laser-accelerated Th ions with about 7 MeV/u will pass through a thin CH{sub 2} layer placed in front of a thicker second Th foil (both forming the reaction target) closely behind the production target and disintegrate into light and heavy fission fragments. In addition, light ions (d,C) from the CD{sub 2} layer of the production target will be accelerated as well, inducing the fission process of {sup 232}Th also in the second Th layer. The laser-accelerated ion bunches with solid-state density, which are about 10{sup 14} times more dense than classically accelerated ion bunches, allow for a high probability that generated fission products can fuse again. The high ion beam density may lead to a strong collective modification of the stopping power, leading to significant range and thus yield enhancement. Using a high-intensity laser as envisaged for the ELI-Nuclear Physics project in Bucharest (ELI-NP), order-of-magnitude estimates promise a fusion yield of about 10{sup 3} ions per laser pulse in the mass range of A = 180-190, thus enabling to approach the r-process waiting point at N = 126.

Thirolf, P. G.; Gross, M.; Allinger, K.; Bin, J.; Henig, A.; Kiefer, D. [Fakultaet fuer Physik, Ludwig-Maximilians Universitaet Muenchen, D-85748 Garching (Germany); Habs, D. [Fakultaet fuer Physik, Ludwig-Maximilians Universitaet Muenchen, D-85748 Garching (Germany); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Ma, W.; Schreiber, J. [Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany)

2011-10-28T23:59:59.000Z

15

The Polymerase Chain Reaction and Branching Processes Fengzhu Sun  

E-Print Network [OSTI]

The Polymerase Chain Reaction and Branching Processes Fengzhu Sun Department of Mathematics, DRB is studied. We also study the distribution of the Hamming distance between two randomly chosen sequences long. The double-stranded DNA molecules are heated to near boiling temperature so that the double

Sun, Fengzhu - Sun, Fengzhu

16

Polymerase chain reaction system using magnetic beads for analyzing a sample that includes nucleic acid  

DOE Patents [OSTI]

A polymerase chain reaction system for analyzing a sample containing nucleic acid includes providing magnetic beads; providing a flow channel having a polymerase chain reaction chamber, a pre polymerase chain reaction magnet position adjacent the polymerase chain reaction chamber, and a post pre polymerase magnet position adjacent the polymerase chain reaction chamber. The nucleic acid is bound to the magnetic beads. The magnetic beads with the nucleic acid flow to the pre polymerase chain reaction magnet position in the flow channel. The magnetic beads and the nucleic acid are washed with ethanol. The nucleic acid in the polymerase chain reaction chamber is amplified. The magnetic beads and the nucleic acid are separated into a waste stream containing the magnetic beads and a post polymerase chain reaction mix containing the nucleic acid. The reaction mix containing the nucleic acid flows to an analysis unit in the channel for analysis.

Nasarabadi, Shanavaz (Livermore, CA)

2011-01-11T23:59:59.000Z

17

Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions  

SciTech Connect (OSTI)

Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A{approx}200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n,xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin states between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.

Fotiades, N.; Nelson, R. O.; Devlin, M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Cizewski, J. A. [Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903 (United States); Kruecken, R. [Physik Department E12, Technische Universitaet Muenchen, D-85748 Garching (Germany); Clark, R. M.; Fallon, P.; Lee, I. Y.; Macchiavelli, A. O. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Becker, J. A.; Younes, W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2011-10-28T23:59:59.000Z

18

Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions  

SciTech Connect (OSTI)

Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A {approx} 200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n, xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin states between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.

Fotiadis, Nikolaos [Los Alamos National Laboratory; Nelson, Ronald O [Los Alamos National Laboratory; Devlin, Matthew [Los Alamos National Laboratory; Cizewski, Jolie A [RUTGERS UNIV.; Krucken, Reiner [TECHNICAL UNIV OF MUNICH; Clark, R M [LBNL; Fallon, Paul [LBNL; Lee, I Yang [LBNL; Macchiavelli, Agusto O [LBNL; Becker, John A [LLNL; Younes, Walid [LLNL

2010-01-01T23:59:59.000Z

19

Fusion-fission and quasifission in the reactions with heavy ions leading to the formation of Hs  

SciTech Connect (OSTI)

Mass and energy distributions of binary reaction products obtained in the reactions {sup 22}Ne+{sup 249}Cf,{sup 26}Mg+{sup 248}Cm,{sup 36}S+{sup 238}U and {sup 58}Fe+{sup 208}Pb leading to Hs isotopes have been measured. At energies below the Coulomb barrier the bimodal fission of Hs*, formed in the reaction {sup 26}Mg+{sup 248}Cm, is observed. In the reaction {sup 36}S+{sup 238}U the considerable part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier the symmetric fragments originate mainly from fusion-fission process for both reactions with Mg and S ions. In the case of the {sup 58}Fe+{sup 208}Pb reaction the quasifission process dominates at all measured energies. The pre- and post-scission neutron multiplicities as a function of the fragment mass have been obtained for the reactions studied.

Itkis, I. M.; Itkis, M. G.; Knyazheva, G. N.; Kozulin, E. M. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

2012-10-20T23:59:59.000Z

20

Fission and quasifission modes in heavy-ion-induced reactions leading to the formation of Hs{sup *}  

SciTech Connect (OSTI)

Mass and energy distributions of binary reaction products obtained in the reactions {sup 22}Ne+{sup 249}Cf,{sup 26}Mg+{sup 248}Cm, {sup 36}S+{sup 238}U, and {sup 58}Fe+{sup 208}Pb have been measured. All reactions lead to Hs isotopes. At energies below the Coulomb barrier the bimodal fission of Hs{sup *}, formed in the reaction {sup 26}Mg+{sup 248}Cm, is observed. In the reaction {sup 36}S+{sup 238}U, leading to the formation of a similar compound nucleus, the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier fusion-fission is the main process leading to the formation of symmetric fragments for both reactions with Mg and S ions. In the case of the {sup 58}Fe+{sup 208}Pb reaction the quasifission process dominates at all measured energies.

Itkis, I. M.; Kozulin, E. M.; Itkis, M. G.; Knyazheva, G. N.; Bogachev, A. A.; Chernysheva, E. V.; Krupa, L.; Oganessian, Yu. Ts.; Zagrebaev, V. I.; Rusanov, A. Ya.; Goennenwein, F.; Dorvaux, O.; Stuttge, L.; Hanappe, F.; Vardaci, E.; Goes Brennand, E. de [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Institute of Nuclear Physics of the National Nuclear Center of Kazakhstan, 050032 Almaty (Kazakhstan); Physikalisches Institut, Universitaet Tuebingen, D-72076 Tuebingen (Germany); Institut Pluridisciplinaire Hubert Curien and Universite de Strasbourg, F-67037 Strasbourg (France); Universite Libre de Bruxelles, CP229, B-1050 Bruxelles, Belgique (Belgium); Istituto Nazionale di Fisica Nucleare and Dipartimento di Scienze Fisiche dell'Universita di Napoli, Napoli (Italy); Departamento de Fisica, Universidade Estadual da Paraiba, 58109-753 Campina Grande (Brazil)

2011-06-15T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Study of the Fusion-Fission Process in the $^{35}Cl+^{24}Mg$ Reaction  

E-Print Network [OSTI]

Fusion-fission and fully energy-damped binary processes of the $^{35}$Cl+$^{24}$Mg reaction were investigated using particle-particle coincidence techniques at a $^{35}$Cl bombarding energy of E$_{lab}$ $\\approx$ 8 MeV/nucleon. Inclusive data were also taken in order to determine the partial wave distribution of the fusion process. The fragment-fragment correlation data show that the majority of events arises from a binary-decay process with a relatively large multiplicity of secondary light-charged particles emitted by the two primary excited fragments in the exit channel. No evidence is observed for ternary-breakup processes, as expected from the systematics recently established for incident energies below 15 MeV/nucleon and for a large number of reactions. The binary-process results are compared with predictions of statistical-model calculations. The calculations were performed using the Extended Hauser-Feshbach method, based on the available phase space at the scission point of the compound nucleus. This new method uses temperature-dependent level densities and its predictions are in good agreement with the presented experimental data, thus consistent with the fusion-fission origin of the binary fully-damped yields.

C. Beck; ; Sl. Cavallaro; ; R. Dayras

1998-04-30T23:59:59.000Z

22

Nested methylation-specific polymerase chain reaction cancer detection method  

DOE Patents [OSTI]

A molecular marker-based method for monitoring and detecting cancer in humans. Aberrant methylation of gene promoters is a marker for cancer risk in humans. A two-stage, or "nested" polymerase chain reaction method is disclosed for detecting methylated DNA sequences at sufficiently high levels of sensitivity to permit cancer screening in biological fluid samples, such as sputum, obtained non-invasively. The method is for detecting the aberrant methylation of the p16 gene, O 6-methylguanine-DNA methyltransferase gene, Death-associated protein kinase gene, RAS-associated family 1 gene, or other gene promoters. The method offers a potentially powerful approach to population-based screening for the detection of lung and other cancers.

Belinsky, Steven A. (Albuquerque, NM); Palmisano, William A. (Edgewood, NM)

2007-05-08T23:59:59.000Z

23

DCHAIN V1.3. Radioactive Decay and Reaction Chain Calculations  

SciTech Connect (OSTI)

DCHAIN calculates the time-dependent daughter populations in radioactive decay and nuclear reaction chains. Chain members can have non-zero initial populations and be produced from the preceding chain member as the result of radioactive decay, a nuclear reaction, or both. Parent-daughter equilibrium times and relative activities at equilibrium can also be calculated. Program input can be supplied interactively or read from ASCII files.

East, L.V. [EG and G Idaho, Inc., Idaho Falls, ID (United States)

1994-04-01T23:59:59.000Z

24

Neutron capture studies: 1, Multiple capture reactions and implications for calculated beta-delayed fission rates: 2, The nuclear level structure of 238Np  

SciTech Connect (OSTI)

Astrophysical r-process calculations of transbismuth elements are of interest because certain actinide pairs can be treated as chronometers in determining the duration of nucleosynthesis. For one such calculation where a particularly long galactic age was derived, 21 + 2 - 4 Gyr, we present evidence that the effect of beta-delayed fission appears to be seriously overestimated in uranium decay chains with A = 252 to 257. With this conclusion, it follows that this estimate of the galactic age must be considered more uncertain than if the calculated rates of beta-delayed fission were found to be acceptable. The nuclear level structure of 238Np has been investigated using the 237Np(n,..gamma..)238Np reaction and the alpha decay of 242mAm as experimental probes. Having established a level scheme for 238Np that includes 47 excited levels and 93 secondary transitions, we find a high degree of correspondence between the experimental band structure and that of a semi-empirical model developed to predict excitations in odd-odd deformed nuclei. 35 refs., 4 figs., 3 tabs.

Hoff, R.W.

1988-02-19T23:59:59.000Z

25

Precise ruthenium fission product isotopic analysis using dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS)  

SciTech Connect (OSTI)

99Tc is a subsurface contaminant of interest at numerous federal, industrial, and international facilities. However, as a mono-isotopic fission product, 99Tc lacks the ability to be used as a signature to differentiate between the different waste disposal pathways that could have contributed to subsurface contamination at these facilities. Ruthenium fission-product isotopes are attractive analogues for the characterization of 99Tc sources because of their direct similarity to technetium with regard to subsurface mobility, and their large fission yields and low natural background concentrations. We developed an inductively coupled plasma mass spectrometry (ICP-MS) method capable of measuring ruthenium isotopes in groundwater samples and extracts of vadose zone sediments. Samples were analyzed directly on a Perkin Elmer ELAN DRC II ICP-MS after a single pass through a 1-ml bed volume of Dowex AG 50W-X8 100-200 mesh cation exchange resin. Precise ruthenium isotopic ratio measurements were achieved using a low-flow Meinhard-type nebulizer and long sample acquisition times (150,000 ms). Relative standard deviations of triplicate replicates were maintained at less than 0.5% when the total ruthenium solution concentration was 0.1 ng/ml or higher. Further work was performed to minimize the impact caused by mass interferences using the dynamic reaction cell (DRC) with O2 as the reaction gas. The aqueous concentrations of 96Mo and 96Zr were reduced by more than 99.7% in the reaction cell prior to injection of the sample into the mass analyzer quadrupole. The DRC was used in combination with stable-mass correction to quantitatively analyze samples containing up to 2-orders of magnitude more zirconium and molybdenum than ruthenium. The analytical approach documented herein provides an efficient and cost-effective way to precisely measure ruthenium isotopes and quantitate total ruthenium (natural vs. fission-product) in aqueous matrixes.

Brown, Christopher F.; Dresel, P. Evan; Geiszler, Keith N.; Farmer, Orville T.

2006-05-09T23:59:59.000Z

26

Model microfluidic platform prototyping : design and fabrication of a Polymerase Chain Reaction (PCR) chip  

E-Print Network [OSTI]

Polymerase Chain Reaction (PCR) is a molecular biology method for the in vitro amplification of nucleic acid molecules, which has wide applications in the areas of genetics, medicine and biochemistry. MEMS technology offers ...

Kumar, Sumeet, Ph. D. Massachusetts Institute of Technology

2009-01-01T23:59:59.000Z

27

Detection of Rhodococcus equi by polymerase chain reaction using species-specific, non-proprietary primers  

E-Print Network [OSTI]

Species-specific primers for the polymerase chain reaction (PCR) for the detection of Rhodococcus equi were developed. These primers were based on unique DNA fragments produced from R. equi reference strains and field isolates. Following random...

Arriaga, Jose Miguel

2002-01-01T23:59:59.000Z

28

Microscopic theory of protein folding rates. II. Local reaction coordinates and chain dynamics  

E-Print Network [OSTI]

Microscopic theory of protein folding rates. II. Local reaction coordinates and chain dynamics John involved in barrier crossing for protein folding are investigated in terms of the chain dynamics of the polymer backbone, completing the microscopic description of protein folding presented in the preceding

Takada, Shoji

29

ChainReaction: uma Variante de Replicac~ao em Cadeia com Coer^encia Causal+  

E-Print Network [OSTI]

, o ChainReaction serve de base a um futuro sistema para Geo-replica¸c~ao (v´arios centros de dados desafios no desenho de sistemas de armazenamento de dados para suporte a aplica¸c~oes na nuvem. Por este propostas nos ´ultimos anos. Este artigo prop~oe um novo sis- tema de armazenamento de dados, chamado Chain

Rodrigues, Luís E.T.

30

Competition of fusion and quasi-fission in the reactions leading to production of the superheavy elements  

E-Print Network [OSTI]

The mechanism of fusion hindrance, an effect observed in the reactions of cold, warm and hot fusion leading to production of the superheavy elements, is investigated. A systematics of transfermium production cross sections is used to determine fusion probabilities. Mechanism of fusion hindrance is described as a competition of fusion and quasi-fission. Available evaporation residue cross sections in the superheavy region are reproduced satisfactorily. Analysis of the measured capture cross sections is performed and a sudden disappearance of the capture cross sections is observed at low fusion probabilities. A dependence of the fusion hindrance on the asymmetry of the projectile-target system is investigated using the available data. The most promising pathways for further experiments are suggested.

M. Veselsky

2003-02-11T23:59:59.000Z

31

Method of carbon chain extension using novel aldol reaction  

DOE Patents [OSTI]

Method of producing C.sub.8-C.sub.15 hydrocarbons comprising providing a ketone starting material; providing an aldol starting material comprising hydroxymethylfurfural; mixing the ketone starting material and the aldol starting material in a reaction in the presence of a proline-containing catalyst selected from the group consisting of Zn(Pro).sub.2, Yb(Pro).sub.2, and combinations thereof, or a catalyst having one of the structures (I), (II) or (III), and in the presence of a solvent, wherein the solvent comprises water and is substantially free of organic solvents, where (I), (II) and (III) respectively are: ##STR00001## where R.sub.1 is a C.sub.1-C.sub.6 alkyl moiety, X=(OH) and n=2. ##STR00002## In (III), X may be CH.sub.2, sulfur or selenium, M may be Zn, Mg, or a lanthanide, and R.sub.1 and R.sub.2 each independently may be a methyl, ethyl, phenyl moiety.

Silks, Louis A; Gordon, John C; Wu, Ruilan; Hangson, Susan Kloek

2013-08-13T23:59:59.000Z

32

Method of carbon chain extension using novel aldol reaction  

DOE Patents [OSTI]

Method of producing C.sub.8-C.sub.15 hydrocarbons. comprising providing a ketone starting material; providing an aldol starting material comprising chloromethylfurfural; mixing the ketone starting material and the aldol starting material in a reaction in the presence of a proline-containing catalyst selected from the group consisting of Zn(Pro).sub.2, Yb(Pro).sub.3, and combinations thereof, or a catalyst having one of the structures (I), (II) or (III), and in the presence of a solvent, wherein the solvent comprises water and is substantially free of organic solvents, where (I), (II) and (III) respectively are: ##STR00001## where R.sub.1 is a C.sub.1-C.sub.6 alkyl moiety, X=(OH) and n=2. ##STR00002## In (III), X may be CH.sub.2, sulfur or selenium, M may be Zn, Mg, or a lanthanide, and R.sub.1 and R.sub.2 each independently may be a methyl, ethyl, phenyl moiety.

Silks, Louis A; Gordon, John C; Wu, Ruilan; Hanson, Susan Kloek

2013-07-30T23:59:59.000Z

33

Reactor as a Source of Antineutrinos: Thermal Fission Energy  

E-Print Network [OSTI]

Deeper insight into the features of a reactor as a source of antineutrinos is required for making further advances in studying the fundamental properties of the neutrino. The relationship between the thermal power of a reactor and the rate of the chain fission reaction in its core is analyzed.

V. Kopeikin; L. Mikaelyan; V. Sinev

2004-10-07T23:59:59.000Z

34

A string reaction coordinate for the folding of a polymer chain  

E-Print Network [OSTI]

We investigate the crystallization mechanism of a single, flexible homopolymer chain with short range attractions. For a sufficiently narrow attractive well, the system undergoes a first-order like freezing transition from an expanded disordered coil to a compact crystalline state. Based on a maximum likelihood analysis of committor values computed for configurations obtained by Wang-Landau sampling, we construct a non-linear string reaction coordinate for the coil-to-crystal transition. In contrast to a linear reaction coordinate, the string reaction coordinate captures the effect of different degrees of freedom controlling different stages of the transition. Our analysis indicates that a combination of the energy and the global crystallinity parameter Q6 provide the most accurate measure for the progress of the transition. While the crystallinity parameter Q6 is most relevant in the initial stages of the crystallization, the later stages are dominated by a decrease in the potential energy.

Leitold, Christian; Dellago, Christoph

2015-01-01T23:59:59.000Z

35

Microscopic Theory of Protein Folding Rates.II: Local Reaction Coordinates and Chain Dynamics  

E-Print Network [OSTI]

The motion involved in barrier crossing for protein folding are investigated in terms of the chain dynamics of the polymer backbone, completing the microscopic description of protein folding presented in the previous paper. Local reaction coordinates are identified as collective growth modes of the unstable fluctuations about the saddle-points in the free energy surface. The description of the chain dynamics incorporates internal friction (independent of the solvent viscosity) arising from the elementary isomerizations of the backbone dihedral angles. We find that the folding rate depends linearly on the solvent friction for high viscosity, but saturates at low viscosity because of internal friction. For $\\lambda$-repressor, the calculated folding rate prefactor, along with the free energy barrier from the variational theory, gives a folding rate that agrees well with the experimentally determined rate under highly stabilizing conditions, but the theory predicts too large a folding rate at the transition midpoint. This discrepancy obtained using a fairly complete quantitative theory inspires a new set of questions about chain dynamics, specifically detailed motions in individual contact formation.

John J. Portman; Shoji Takada; Peter G. Wolynes

2000-08-30T23:59:59.000Z

36

Investigation of the reaction {sup 208}Pb({sup 18}O, f): Fragment spins and phenomenological analysis of the angular anisotropy of fission fragments  

SciTech Connect (OSTI)

The average multiplicity of gamma rays emitted by fragments originating from the fission of {sup 226}Th nuclei formed via a complete fusion of {sup 18}O and {sup 208}Pb nuclei at laboratory energies of {sup 18}O projectile ions in the range E{sub lab} = 78-198.5 MeV is measured and analyzed. The total spins of fission fragments are found and used in an empirical analysis of the energy dependence of the anisotropy of these fragments under the assumption that their angular distributions are formed in the vicinity of the scission point. The average temperature of compound nuclei at the scission point and their average angular momenta in the entrance channel are found for this analysis. Also, the moments of inertia are calculated for this purpose for the chain of fissile thorium nuclei at the scission point. All of these parameters are determined at the scission point by means of three-dimensional dynamical calculations based on Langevin equations. A strong alignment of fragment spins is assumed in analyzing the anisotropy in question. In that case, the energy dependence of the anisotropy of fission fragments is faithfully reproduced at energies in excess of the Coulomb barrier (E{sub c.m.} - E{sub B} {>=} 30 MeV). It is assumed that, as the excitation energy and the angular momentum of a fissile nucleus are increased, the region where the angular distributions of fragments are formed is gradually shifted from the region of nuclear deformations in the vicinity of the saddle point to the region of nuclear deformations in the vicinity of the scission point, the total angular momentum of the nucleus undergoing fission being split into the orbital component, which is responsible for the anisotropy of fragments, and the spin component. This conclusion can be qualitatively explained on the basis of linear-response theory.

Rusanov, A. Ya. [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan)], E-mail: rusanov@inp.kz; Adeev, G. D. [Omsk State University (Russian Federation); Itkis, M. G.; Karpov, A. V. [Joint Institute for Nuclear Research (Russian Federation); Nadtochy, P. N. [Omsk State University (Russian Federation); Pashkevich, V. V.; Pokrovsky, I. V.; Salamatin, V. S. [Joint Institute for Nuclear Research (Russian Federation); Chubarian, G. G. [Texas A and M University, Cyclotron Institute (United States)

2007-10-15T23:59:59.000Z

37

Time scale of the fission process in the reaction 50A MeV 20Ne + 165Ho  

E-Print Network [OSTI]

source (average neutron multiplicity of 3. ?8). The typical set-up for the electronics of the detector is shown in Fig. 10 [16]. The neutron multiplicity was measured in coincidence with the detection of two fission fragments in the ICD detectors... EXPERIMENTAL SET UP . 17 II. 1 Experimental Set-up II. 2 The Neutron Ball II. 3 Calibration of Light-Charged Particle Telescopes and Fission Frag- ment Detectors 17 18 21 III DATA ANALYSIS 28 III. 1 Frame of Reference . III. 2 Experimental Techniques...

Mdeiwayeh, Nader

2012-06-07T23:59:59.000Z

38

Low Energy Fission of {sup 256}No, {sup 270}Sg, {sup 271}Hs and {sup 286}112 Nuclei Formed in Reactions with {sup 22}Ne and {sup 48}Ca Ions  

SciTech Connect (OSTI)

The fusion-fission reactions {sup 22}Ne + {sup 248}Cm and {sup 22}Ne + {sup 249}Cf were investigated at projectile energies equal to 102 and 127 MeV. Mass-energy distributions and yields are shown. Two-dimensional plots of TKE vs fragment mass are also shown for {sup 48}Ca reactions at 230 MeV with {sup 208}Pb and {sup 238}U, leading to {sup 256}No and {sup 286}112.

Itkis, M.G.; Kondratiev, N.A.; Kozulin, E.M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I.V.; Prokhorova, E.V.; Rusanov, A. Ya.

1999-12-31T23:59:59.000Z

39

Neutron Emission in Fission And Quasi-Fission of Hs  

SciTech Connect (OSTI)

Mass and energy distributions of fission-like fragments obtained in the reactions {sup 26}Mg+{sup 248}Cm, {sup 36}S+{sup 238}U and {sup 58}Fe+{sup 208}Pb leading to the formation of {sup 266,274}Hs are reported. From the analysis of TKE distributions for symmetric fragment it was found that at energies below the Coulomb barrier the bimodal fission of {sup 274}Hs, formed in the reaction {sup 26}Mg+{sup 248}Cm, is observed, while in the reaction {sup 36}S+{sup 238}U at these energies the main part of the symmetric fragments arises from the quasi-fission process. At energies above the Coulomb barrier the fusion-fission is a main process leading to the formation of symmetric fragment for the both reactions. In the case of {sup 58}Fe+{sup 208}Pb reaction the quasi-fission process is the main reaction mechanism at all measured energies. The pre- and post-scission neutron multiplicities as a function of the fragment mass have been obtained for all studied reactions.

Itkis, I. M.; Itkis, M. G.; Knyazheva, G. N.; Kozulin, E. M.; Krupa, L. [Flerov Laboratory of Nuclear Reactions, JINR, Dubna (Russian Federation); Hanappe, F. [Universite Libre de Bruxelles, Belgique (Belgium); Dorvaux, O.; Stuttge, L. [Institut de Recherches Subatomiques, Strasbourg (France)

2010-04-30T23:59:59.000Z

40

First-Hand Recollections of the First Self-Sustaining Chain Reaction  

Broader source: Energy.gov [DOE]

Seventy years later, two of the men present at the first nuclear reaction recall the events of the memorable day.

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

A comparison of three serological assays, protein gel electrophoresis and the polymerase chain reaction for the detection of Chlomydia psittici infections in pet birds  

E-Print Network [OSTI]

: complement fixation (CF), elementary body agglutination (EBA), immunofluorescent antibodies (IFA), polymerase chain reaction (PCR), protein gel electrophoresis. Comparison of the results obtained showed a strong statistical association between EBA to CF, PCR...

Hofle, Michael David

2012-06-07T23:59:59.000Z

42

Investigation of the {sup 208}Pb({sup 18}O, f) fission reaction: Mass-energy distributions of fission fragments and their correlation with the gamma-ray multiplicity  

SciTech Connect (OSTI)

The mass-energy distributions of fragments originating from the fission of the compound nucleus {sup 226}Th and their correlations with the multiplicity of gamma rays emitted from these fragments are measured and analyzed in {sup 18}O + {sup 208}Pb interaction induced by projectile oxygen ions of energy in the range E{sub lab} = 78-198.5 MeV. Manifestations of an asymmetric fission mode, which is damped exponentially with increasing E{sub lab}, are demonstrated. Theoretical calculations of fission valleys reveal that only two independent valleys, symmetric and asymmetric, exist in the vicinity of the scission point. The dependence of the multiplicity of gamma rays emitted from both fission fragments on their mass, M{sub {gamma}}(M), has a complicated structure and is highly sensitive to shell effects in both primary and final fragments. A two-component analysis of the dependence M{sub {gamma}}(M) shows that the asymmetric mode survives in fission only at low partial-wave orbital angular momenta of compound nuclei. It is found that, for all E{sub lab}, the gamma-ray multiplicity M{sub {gamma}}as a function of the total kinetic energy (TKE) of fragments, M{sub {gamma}}(TKE), decreases linearly with increasing TKE. An analysis of the energy balance in the fission process at the laboratory energy of E{sub lab} = 78 MeV revealed the region of cold fission of fragments whose total kinetic energy is TKE {approx}Q{sub max}.

Rusanov, A. Ya., E-mail: rusanov@inp.k [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan); Itkis, M. G.; Kondratiev, N. A.; Pashkevich, V. V.; Pokrovsky, I. V.; Salamatin, V. S. [Joint Institute for Nuclear Research (Russian Federation); Chubarian, G. G. [Texas A and M University, Cyclotron Institute (United States)

2008-06-15T23:59:59.000Z

43

Investigation of the reaction {sup 208}Pb({sup 18}O, f): Folding angular distributions of fission fragments and gamma-ray multiplicity  

SciTech Connect (OSTI)

Correlations between folding angular distributions of fission fragments and the gamma-ray multiplicity are studied for {sup 18}O + {sup 208}Pb interactions at energies of the beam of {sup 18}O ions in the range E{sub lab} = 78-198.5 MeV. The probabilities are determined for complete-and incomplete-fusion processes inevitably followed by the fission of nuclei formed in these processes. It is found that the probability of incomplete fusion followed by fission increases with increasing energy of bombarding ions. It is shown that, for the incomplete-fusion process, folding angular distributions of fission fragments have a two-component structure. The width of folding angular distributions (FWHM) for complete fusion grows linearly with increasing energy of {sup 18}O ions. The multiplicity of gamma rays from fission fragments as a function of the linear-momentum transfer behaves differently for different energies of projectile ions. This circumstance is explained here by the distinction between the average angular momenta of participant nuclei in the fusion and fission channels, which is due to the difference in the probabilities of fission in the cases where different numbers of nucleons are captured by the target nucleus.

Rusanov, A. Ya. [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan)], E-mail: rusanov@inp.kz; Itkis, M. G.; Kondratiev, N. A.; Pokrovsky, I. V.; Salamatin, V. S. [Joint Institute for Nuclear Research (Russian Federation); Chubarian, G. G. [Cyclotron Institute, Texas A and M University (United States)

2007-10-15T23:59:59.000Z

44

Microscopic Description of Nuclear Fission Dynamics  

E-Print Network [OSTI]

We discuss possible avenues to study fission dynamics starting from a time-dependent mean-field approach. Previous attempts to study fission dynamics using the time-dependent Hartree-Fock (TDHF) theory are analyzed. We argue that different initial conditions may be needed to describe fission dynamics depending on the specifics of the fission phenomenon and propose various approaches towards this goal. In particular, we provide preliminary calculations for studying fission following a heavy-ion reaction using TDHF with a density contraint. Regarding prompt muon-induced fission, we also suggest a new approach for combining the time-evolution of the muonic wave function with a microscopic treatment of fission dynamics via TDHF.

A. S. Umar; V. E. Oberacker; J. A. Maruhn; P. -G. Reinhard

2010-03-22T23:59:59.000Z

45

MODELING AND FISSION CROSS SECTIONS FOR AMERICIUM.  

SciTech Connect (OSTI)

This is the final report of the work performed under the LANL contract on the modeling and fission cross section for americium isotopes (May 2004-June 2005). The purpose of the contract was to provide fission cross sections for americium isotopes with the nuclear reaction model code EMPIRE 2.19. The following work was performed: (1) Fission calculations capability suitable for americium was implemented to the EMPIRE-2.19 code. (2) Calculations of neutron-induced fission cross sections for {sup 239}Am to {sup 244g}Am were performed with EMPIRE-2.19 for energies up to 20 MeV. For the neutron-induced reaction of {sup 240}Am, fission cross sections were predicted and uncertainties were assessed. (3) Set of fission barrier heights for each americium isotopes was chosen so that the new calculations fit the experimental data and follow the systematics found in the literature.

ROCHMAN, D.; HERMAN, M.; OBLOZINSKY, P.

2005-05-01T23:59:59.000Z

46

Benchmarking Nuclear Fission Theory  

E-Print Network [OSTI]

We suggest a small set of fission observables to be used as test cases for validation of theoretical calculations. The purpose is to provide common data to facilitate the comparison of different fission theories and models. The proposed observables are chosen from fission barriers, spontaneous fission lifetimes, fission yield characteristics, and fission isomer excitation energies.

Bertsch, G F; Nazarewicz, W; Talou, P

2015-01-01T23:59:59.000Z

47

Benchmarking Nuclear Fission Theory  

E-Print Network [OSTI]

We suggest a small set of fission observables to be used as test cases for validation of theoretical calculations. The purpose is to provide common data to facilitate the comparison of different fission theories and models. The proposed observables are chosen from fission barriers, spontaneous fission lifetimes, fission yield characteristics, and fission isomer excitation energies.

G. F. Bertsch; W. Loveland; W. Nazarewicz; P. Talou

2015-02-20T23:59:59.000Z

48

Fission meter  

DOE Patents [OSTI]

A neutron detector system for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source.

Rowland, Mark S. (Alamo, CA); Snyderman, Neal J. (Berkeley, CA)

2012-04-10T23:59:59.000Z

49

Fission theory: Its relevance to the nuclear cross section data base  

SciTech Connect (OSTI)

The development of fission reaction theory in relation to its predictive power in the calculation of neutron cross-sections is reviewed. The topics covered include the transition state spectrum and the channel theory; the discovery of complex topography in the fission barrier and the consequences of intermediate structure in fission cross-sections; the evidence of experimental data in parameterizing the fission barrier; and the role of other aspects of collective nuclear motion in controlling fission reaction rates. 51 refs., 6 figs.

Lynn, J.E.

1989-01-01T23:59:59.000Z

50

Conservation of Isospin in Neutron-Rich Fission Fragments  

E-Print Network [OSTI]

On the occasion of the $75^{th}$ anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavy-ion reactions $^{238}$U($^{18}$O,f) and $^{208}$Pb($^{18}$O,f) as well as a thermal neutron fission reaction $^{245}$Cm(n$^{th}$,f). We find that the conservation of the total isospin explains the overall trend in the observed relative yields of fragment masses in each fission pair partition. The isospin values involved are very large making the effect dramatic. The findings open the way for more precise calculations of fission fragment distributions in heavy nuclei and may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation of decay heat in the fission phenomenon.

Ashok Kumar Jain; Deepika Choudhury; Bhoomika Maheshwari

2014-08-11T23:59:59.000Z

51

Terracentric Nuclear Fission Reactor: Background, Basis, Feasibility, Structure, Evidence, and Geophysical Implications  

E-Print Network [OSTI]

The background, basis, feasibility, structure, evidence, and geophysical implications of a naturally occurring Terracentric nuclear fission georeactor are reviewed. For a nuclear fission reactor to exist at the center of the Earth, all of the following conditions must be met: (1) There must originally have been a substantial quantity of uranium within Earth's core; (2) There must be a natural mechanism for concentrating the uranium; (3) The isotopic composition of the uranium at the onset of fission must be appropriate to sustain a nuclear fission chain reaction; (4) The reactor must be able to breed a sufficient quantity of fissile nuclides to permit operation over the lifetime of Earth to the present; (5) There must be a natural mechanism for the removal of fission products; (6) There must be a natural mechanism for removing heat from the reactor; (7) There must be a natural mechanism to regulate reactor power level, and; (8) The location of the reactor or must be such as to provide containment and prevent meltdown. Herndon's georeactor alone is shown to meet those conditions. Georeactor existence evidence based upon helium measurements and upon antineutrino measurements is described. Geophysical implications discussed include georeactor origin of the geomagnetic field, geomagnetic reversals from intense solar outbursts and severe Earth trauma, as well as georeactor heat contributions to global dynamics.

J. Marvin Herndon

2013-12-31T23:59:59.000Z

52

Nuclear fission and nuclear safeguards: Common technologies and challenges  

SciTech Connect (OSTI)

Nuclear fission and nuclear safeguards have much in common, including the basic physical phenomena and technologies involved as well as the commitments and challenges posed by expanding nuclear programs in many countries around the world. The unique characteristics of the fission process -- such as prompt and delayed neutron and gamma ray emission -- not only provide the means of sustaining and controlling the fission chain reaction, but also provide unique ''signatures'' that are essential to quantitative measurement and effective safeguarding of key nuclear materials (notably /sup 239/Pu and /sup 235/U) against theft, loss, or diversion. In this paper, we trace briefly the historical emergence of safeguards as an essential component of the expansion of the nuclear enterprise worldwide. We then survey the major categories of passive and active nondestructive assay techniques that are currently in use or under development for rapid, accurate measurement and verification of safe-guarded nuclear materials in the many forms in which they occur throughout the nuclear fuel cycle. 23 refs., 14 figs.

Keepin, G.R.

1989-01-01T23:59:59.000Z

53

Event-by-Event Fission with FREYA  

SciTech Connect (OSTI)

The recently developed code FREYA (Fission Reaction Event Yield Algorithm) generates large samples of complete fission events, consisting of two receding product nuclei as well as a number of neutrons and photons, all with complete kinematic information. Thus it is possible to calculate arbitrary correlation observables whose behavior may provide unique insight into the fission process. The presentation first discusses the present status of FREYA, which has now been extended up to energies where pre-equilibrium emission becomes significant and one or more neutrons may be emitted prior to fission. Concentrating on {sup 239}Pu(n,f), we discuss the neutron multiplicity correlations, the dependence of the neutron energy spectrum on the neutron multiplicity, and the relationship between the fragment kinetic energy and the number of neutrons and their energies. We also briefly suggest novel fission observables that could be measured with modern detectors.

Randrup, J; Vogt, R

2010-11-09T23:59:59.000Z

54

Reexamination of fission fragment angular distributions and the fission process: Formalism  

SciTech Connect (OSTI)

The theory of fission fragment angular distributions is examined and the universally used expression is found to be valid only under restrictive assumptions. A more general angular distribution formula is derived and applied to recent data of high spin systems. At the same time it is shown that the strong anisotropies observed from such systems can be understood without changing the essential basis of standard fission theory. The effects of reaction mechanisms other than complete fusion on fission fragment angular distributions are discussed and possible angular distribution signatures of noncompound nucleus formation are mentioned.

Bond, P.D.

1985-08-01T23:59:59.000Z

55

Time dependence of delayed neutron emission for fissionable isotope identification  

SciTech Connect (OSTI)

The time dependence of delayed neutron emission was examined as a method of fissionable isotope identification. A pulsed bremsstrahlung photon beam was used to induce photofission reactions in {sup 238}U, {sup 232}Th, and {sup 239}Pu targets. The resulting delayed neutron emission was recorded between irradiating pulses and is a well-known technique for fissionable material detection. Monitoring the decay of delayed neutron emission between irradiating pulses demonstrates the ability to not only detect the presence of fissionable materials, but also to identify which fissionable isotope is present.

Kinlaw, M.T.; Hunt, A.W. [Idaho Accelerator Center, Idaho State University, Pocatello, Idaho 83209-8263 (United States); Department of Physics, Idaho State University, Pocatello, Idaho 83209-8106 (United States)

2005-06-20T23:59:59.000Z

56

Transfer-induced fission of superheavy nuclei  

SciTech Connect (OSTI)

Possibilities of transfer-induced fission of new isotopes of superheavy nuclei with charge numbers 103-108 are studied for the first time in the reactions {sup 48}Ca+{sup 244,246,248}Cm at energies near the corresponding Coulomb barriers. The predicted cross sections are found to be measurable with the detection of three-body final states.

Adamian, G. G. [Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Institute of Nuclear Physics, Tashkent, UZ-702132 Uzbekistan (Uzbekistan); Antonenko, N. V.; Zubov, A. S. [Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Sargsyan, V. V. [Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Yerevan State University, Yerevan (Armenia); Scheid, W. [Institut fuer Theoretische Physik der Justus-Liebig-Universitaet, D-35392 Giessen (Germany)

2010-07-15T23:59:59.000Z

57

Our 50-year odyssey with fission: Summary  

SciTech Connect (OSTI)

On the occasion of this International Conference on Fifty Years Research in Nuclear Fission, we summarize our present understanding of the fission process and the challenges that lie ahead. The basic properties of fission arise from a delicate competition between disruptive Coulomb forces, cohesive nuclear forces, and fluctuating shell and pairing forces. These static forces are primarily responsible for such experimental phenomena as deformed ground-state nuclear shapes, fission into fragments of unequal size, sawtooth neutron yields, spontaneously fissioning isomers, broad resonances and narrow intermediate structure in fission cross sections, and cluster radioactivity. However, inertial and dissipative forces also play decisive roles in the dynamical evolution of a fissioning nucleus. The energy dissipated between the saddle and scission points is small for low initial excitation energy at the saddle point and increases with increasing excitation energy. At moderate excitation energies, the dissipation of collective energy into internal single-particle excitation energy proceeds largely through the interaction of nucleons with the mean field and with each other in the vicinity of the nuclear surface, as well as through the transfer of nucleons between the two portions of the evolving dumbell-like system. These unique dissipation mechanisms arise from the Pauli exclusion principle for fermions and the details of the nucleon-nucleon interaction, which make the mean free path of a nucleon near the Fermi surface at low excitation energy longer than the nuclear radius. With its inverse process of heavy-ion fusion reactions, fission continues to yield surprises in the study of large-amplitude collective nuclear motion. 87 refs., 12 figs.

Nix, J.R.

1989-01-01T23:59:59.000Z

58

Fission gas detection system  

DOE Patents [OSTI]

A device for collecting fission gas released by a failed fuel rod which device uses a filter to pass coolant but which filter blocks fission gas bubbles which cannot pass through the filter due to the surface tension of the bubble.

Colburn, Richard P. (Pasco, WA)

1985-01-01T23:59:59.000Z

59

Liquid uranium alloy-helium fission reactor  

DOE Patents [OSTI]

This invention describes a nuclear fission reactor which has a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200 to 1800/sup 0/C range, and even higher to 2500/sup 0/C.

Minkov, V.

1984-06-13T23:59:59.000Z

60

Liquid uranium alloy-helium fission reactor  

DOE Patents [OSTI]

This invention teaches a nuclear fission reactor having a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200.degree.-1800.degree. C. range, and even higher to 2500.degree. C., limited only by the thermal effectiveness of the structural materials, increasing the efficiency of power generation from the normal 30-35% with 300.degree.-500.degree. C. upper limit temperature to 50-65%. Irradiation of the circulating liquid fuel, as contrasted to only localized irradiation of a solid fuel, provides improved fuel utilization.

Minkov, Vladimir (Skokie, IL)

1986-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Excitation energy dependence of fission in the mercury region  

E-Print Network [OSTI]

Background: Recent experiments on beta-delayed fission reported an asymmetric mass yield in the neutron-deficient nucleus 180Hg. Earlier experiments in the mass region A=190-200 close to the beta-stability line, using the (p,f) and (\\alpha,f) reactions, observed a more symmetric distribution of fission fragments. While the beta-delayed fission of 180Hg can be associated with relatively low excitation energy, this is not the case for light-ion reactions, which result in warm compound nuclei. Purpose: To elucidate the roles of proton and neutron numbers and excitation energy in determining symmetric and asymmetric fission yields, we compute and analyze the isentropic potential energy surfaces of 174,180,198Hg and 196,210Po. Methods: We use the finite-temperature superfluid nuclear density functional theory, for excitation energies up to E*=30MeV and zero angular momentum. For our theoretical framework, we consider the Skyrme energy density functional SkM* and a density-dependent pairing interaction. Results: For 174,180Hg, we predict fission pathways consistent with asymmetric fission at low excitation energies, with the symmetric fission pathway opening very gradually as excitation energy is increased. For 198Hg and 196Po, we expect the nearly-symmetric fission channel to dominate. 210Po shows a preference for a slightly asymmetric pathway at low energies, and a preference for a symmetric pathway at high energies. Conclusions: Our self-consistent theory suggests that excitation energy weakly affects the fission pattern of the nuclei considered. The transition from the asymmetric fission in the proton-rich nuclei to a more symmetric fission in the heavier isotopes is governed by the shell structure of pre-scission configurations.

J. D. McDonnell; W. Nazarewicz; J. A. Sheikh; A. Staszczak; M. Warda

2014-06-26T23:59:59.000Z

62

Fission barrier, damping of shell correction and neutron emission in the fission of A$\\sim$200  

E-Print Network [OSTI]

Decay of $^{210}$Po compound nucleus formed in light and heavy-ion induced fusion reactions has been analyzed simultaneously using a consistent prescription for fission barrier and nuclear level density incorporating shell correction and its damping with excitation energy. Good description of all the excitation functions have been achieved with a fission barrier of 21.9 $\\pm$ 0.2 MeV. For this barrier height, the predicted statistical pre-fission neutrons in heavy-ion fusion-fission are much smaller than the experimental values, implying the presence of dynamical neutrons due to dissipation even at these low excitation energies ($\\sim$ 50~MeV) in the mass region A $\\sim$ 200. When only heavy-ion induced fission excitation functions and the pre-fission neutron multiplicities are included in the fits, the deduced best fit fission barrier depends on the assumed fission delay time during which dynamical neutrons can be emitted. A fission delay of (0.8 $\\pm$ 0.1 )$\\times 10^{-19}$ s has been estimated correspondin...

Mahata, K; Kapoor, S S

2015-01-01T23:59:59.000Z

63

3He- and 4He-induced nuclear fission - a test of the transition state method  

E-Print Network [OSTI]

Fission in 3He and 4He induced reactions at excitation energies between the fission barrier and 140 MeV has been investigated. Twentythree fission excitation functions of various compound nuclei in different mass regions are shown to scale exactly according to the transition state prediction once the shell effects are accounted for. New precise measurements of excitation functions in a mass region where shell effects are very strong, allow one to test the predictions with an even higher accuracy. The fact that no deviations from the transition state method have been observed within the experimentally investigated excitation energy regime allows one to assign limits for the fission transient time. The precise measurement of fission excitation functions of neighboring isotopes enables us to experimentally estimate the first chance fission probability. Even if only first chance fission is investigated, no evidence for fission transient times larger than 30 zs can be found.

Th. Rubehn; K. X. Jing; L. G. Moretto; L. Phair; K. Tso; G. J. Wozniak

1997-04-18T23:59:59.000Z

64

Singlet fission photovoltaics  

E-Print Network [OSTI]

The efficiency of a solar cell is restricted by the "single junction limit," whereby photons with energy higher than the bandgap lose energy by thermalization. Singlet exciton fission splits a high-energy molecular excitation ...

Lee, Jiye

2013-01-01T23:59:59.000Z

65

Electron-capture delayed fission properties of [sup 228]Np  

SciTech Connect (OSTI)

Electron-capture delayed fission was positively identified for the first time in [sup 228]Np produced via the [sup 233]U(50-MeV [ital p],6[ital n])[sup 228]Np reaction. The half-life of the observed fission activity was measured to be 61.4[plus minus]1.4 s. The ECDF mode was verified by an x-ray--fission coincidence experiment. Only about 25% of the expected x-ray--fission coincidences were detected which indicates that [sup 228]U does not have a fission isomer populated by the electron-capture and that the overall lifetime of the high-energy states populated by the electron-capture is less than about 10[sup [minus]17] s. The fission activity was assigned to ECDF of [sup 228]Np based on chemical separation and observation of known progeny activities. The ratio of electron-capture to alpha decay is 1.5[plus minus]0.4 for [sup 228]Np. The production cross section for [sup 228]Np is 35[plus minus]10 [mu]b and the delayed fission probability is (2.0[plus minus]0.9)[times]10[sup [minus]4]. The kinetic energies of coincident fission fragments were measured and a pre-neutron emission, most probable total kinetic energy, of 169[plus minus]6 MeV was obtained. The mass-yield distribution was found to be predominantly asymmetric.

Kreek, S.A.; Hall, H.L.; Gregorich, K.E.; Henderson, R.A.; Leyba, J.D.; Czerwinski, K.R.; Kadkhodayan, B.; Neu, M.P.; Kacher, C.D.; Hamilton, T.M.; Lane, M.R.; Sylwester, E.R.; Tuerler, A.; Lee, D.M.; Nurmia, M.J.; Hoffman, D.C. (Chemistry Department, University of California, Berkeley, California 94720 (United States) Nuclear Science Division, Lawrence Berkeley Laboratory, MS-70A/3307 Berkeley, California 94720 (United States))

1994-11-01T23:59:59.000Z

66

Introducing the Fission-Fusion Reaction Process: Using a Laser-Accelerated Th Beam to produce Neutron-Rich Nuclei towards the N=126 Waiting Point of the r Process  

E-Print Network [OSTI]

We propose to produce neutron-rich nuclei in the range of the astrophysical r-process around the waiting point N=126 by fissioning a dense laser-accelerated thorium ion bunch in a thorium target (covered by a CH2 layer), where the light fission fragments of the beam fuse with the light fission fragments of the target. Via the 'hole-boring' mode of laser Radiation Pressure Acceleration using a high-intensity, short pulse laser, very efficiently bunches of 232Th with solid-state density can be generated from a Th layer, placed beneath a deuterated polyethylene foil, both forming the production target. Th ions laser-accelerated to about 7 MeV/u will pass through a thin CH2 layer placed in front of a thicker second Th foil closely behind the production target and disintegrate into light and heavy fission fragments. In addition, light ions (d,C) from the CD2 production target will be accelerated as well to about 7 MeV/u, inducing the fission process of 232Th also in the second Th layer. The laser-accelerated ion bunches with solid-state density, which are about 10^14 times more dense than classically accelerated ion bunches, allow for a high probability that generated fission products can fuse again. In contrast to classical radioactive beam facilities, where intense but low-density radioactive beams are merged with stable targets, the novel fission-fusion process draws on the fusion between neutron-rich, short-lived, light fission fragments both from beam and target. The high ion beam density may lead to a strong collective modification of the stopping power in the target, leading to significant range enhancement. Using a high-intensity laser as envisaged for the ELI-Nuclear Physics project in Bucharest (ELI-NP), estimates promise a fusion yield of about 10^3 ions per laser pulse in the mass range of A=180-190, thus enabling to approach the r-process waiting point at N=126.

D. Habs; P. G. Thirolf; M. Gross; K. Allinger; J. Bin; A. Henig; D. Kiefer; W. Ma; J. Schreiber

2010-09-10T23:59:59.000Z

67

Measurements of delayed neutron decay constants and fission yields from {sup 235}U, {sup 237}Np, {sup 241}Am, and {sup 243}Am  

SciTech Connect (OSTI)

Isotopes of the higher actinide elements are produced as a result of successive radiative capture reactions in the uranium fuel of nuclear reactors. Typically, these transuranic isotopes decay through long chains, have long half-lives, and dominate the long-term toxicity of spent reactor fuel. One of the options for high level waste management is to remove the higher actinide elements from spent fuel by chemical processing, to load them into new special fuel elements, and to transmute them by neutron-induced fission into shorter-lived fission fragments. Reactors designed to achieve high actinide fission (transmutation) rates are called actinide burners. In such reactors, the actinide wastes would constitute much of the fissionable fuel. Due to the high transuranic isotope loadings in the fuel of actinide burners, the neutronic properties of the higher actinide isotopes will have a significant effect on the criticality and safety characteristics of such reactors. While there is an extensive operational database for reactors fueled with uranium and plutonium, operating experience with fuel containing large amounts of actinide wastes is quite limited. Two important neutronic properties of actinide burner cores are their reactivity and their delayed neutron fraction. Both of these properties will be strongly influenced by the neutronic characteristics of the actinide waste isotopes. Here, delayed neutron yields and decay constants for {sup 235}U, {sup 237}Np, {sup 241}Am, and {sup 243}Am were measured at the Texas A and M University TRIGA reactor using a fast pneumatic transfer system. The detection system consisted of an array of BF{sub 3} proportional counters embedded in a polyethylene cylinder. The measured values of the total delayed neutron yield per 100 fissions from thermal neutron-induced fission of {sup 235}U, {sup 237}Np, {sup 241}Am, and {sup 243}Am were determined to be 1.59 {+-} 0.04, 1.29 {+-} 0.04, 0.49 {+-} 0.02, and 0.84 {+-} 0.04, respectively.

Saleh, H.H.; Parish, T.A. [Texas A and M Univ., College Station, TX (United States). Dept. of Nuclear Engineering; Raman, S. [Oak Ridge National Lab., TN (United States); Shinohara, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)

1997-01-01T23:59:59.000Z

68

Call Title: Nuclear Fission and Radiation Protection Call Identifier: FP7-Fission-2009  

E-Print Network [OSTI]

Fission-2.2 Fission-2009-2.2.1: Conceptual design of lead and gas cooled fast reactor systems Max. of 2 and transmutation Fission-1.2 (refer to Fission-2.3) Reactor Systems: Fission-2 Fission-2.1 Fission-2009-2.1.1: Structural integrity assessment for safety and lifetime management of the Reactor Coolant System piping

De Cindio, Fiorella

69

Group Constants Generation of the Pseudo Fission Products for Fast Reactor Burnup Calculations  

SciTech Connect (OSTI)

The pseudo fission products for the burnup calculations of the liquid metal fast reactor were generated. The cross-section data and fission product yield data of ENDF/B-VI were used for the pseudo fission product data of U-235, U-238, Pu-239, Pu-240, Pu-241, and Pu-242. The pseudo fission product data can be used with the KAFAX-F22 or -E66, which are the MATXS-format libraries for analyses of the liquid metal fast reactor at KAERI and were distributed through the OECD/NEA. The 80-group MATXS-format libraries of the 172 fission products were generated and the burnup chains for generation of the pseudo fission products were prepared.

Gil, Choong-Sup; Kim, Do Heon; Chang, Jonghwa [Korea Atomic Energy Research Institute, 150 Dukjin-dong, Yusung-gu, Taejon (Korea, Republic of)

2005-05-24T23:59:59.000Z

70

A New Method of Prompt Fission Neutron Energy Spectrum Unfolding  

SciTech Connect (OSTI)

The prompt neutron emission in spontaneous fission of {sup 252}Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. The goal was to find out the reasons of a long time existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of fission fragments (FF). On the one hand the {sup 252}Cf(sf) reaction is one of the main references for nuclear data, on the other hand the understanding of PFN emission mechanism is very important for nuclear fission theory. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 10{sup 7} fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

Zeynalova, O. V. [Moscow State Institute of Radioengineering, Electronics and Automation, Moscow (Russian Federation); Joint Institute for Nuclear Research, Dubna (Russian Federation); Zeynalov, Sh. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Hambsch, F.-J.; Oberstedt, S. [EC-JRC-Institute for Reference Materials and Measurements, Geel (Belgium)

2010-11-25T23:59:59.000Z

71

The role of chemical reactions in the Chernobyl accident  

SciTech Connect (OSTI)

It is shown that chemical reactions played an essential role in the Chernobyl accident at all of its stages. It is important that the reactor before the explosion was at maximal xenon poisoning, and its reactivity, apparently, was not destroyed by the explosion. The reactivity release due to decay of Xe-235 on the second day after the explosion led to a reactor power of 80-110 MW. Owing to this power, the chemical reactions of reduction of uranium, plutonium, and other metals at a temperature of about 2000 Degree-Sign C occurred in the core. The yield of fission products thus sharply increased. Uranium and other metals flew down in the bottom water communications and rooms. After reduction of the uranium and its separation from the graphite, the chain reaction stopped, the temperature of the core decreased, and the activity yield stopped.

Grishanin, E. I., E-mail: egrishanin@orexovo.net [Russian Research Center Kurchatov Institute (Russian Federation)

2010-12-15T23:59:59.000Z

72

Fission cross section calculations of actinides with EMPIRE code  

SciTech Connect (OSTI)

The cross sections of the neutron induced reactions on {sup 233,234,236}U, {sup 237}Np, {sup 238,242}Pu, {sup 241,243}Am, {sup 242,246}Cm carried out in the energy range 1 keV-20 MeV with EMPIRE code are presented, emphasizing the fission channel. Beside a consistent, accurate set of evaluations, the paper contains arguments supporting the choice of the reaction models and input parameters. A special attention is paid to the fission parameters and their uncertainties.

Sin, M.; Oblozinsky, P.; Herman,M.; Capote,R.

2010-04-30T23:59:59.000Z

73

Measurements of actinide-fission product yields in Caliban and Prospero metallic core reactor fission neutron fields  

SciTech Connect (OSTI)

In the 1970's and early 1980's, an experimental program was performed on the facilities of the CEA Valduc Research Center to measure several actinide-fission product yields. Experiments were, in particular, completed on the Caliban and Prospero metallic core reactors to study fission-neutron-induced reactions on {sup 233}U, {sup 235}U, and {sup 239}Pu. Thick actinide samples were irradiated and the number of nuclei of each fission product was determined by gamma spectrometry. Fission chambers were irradiated simultaneously to measure the numbers of fissions in thin deposits of the same actinides. The masses of the thick samples and the thin deposits were determined by mass spectrometry and alpha spectrometry. The results of these experiments will be fully presented in this paper for the first time. A description of the Caliban and Prospero reactors, their characteristics and performances, and explanations about the experimental approach will also be given in the article. A recent work has been completed to analyze and reinterpret these measurements and particularly to evaluate the associated uncertainties. In this context, calculations have also been carried out with the Monte Carlo transport code Tripoli-4, using the published benchmarked Caliban description and a three-dimensional model of Prospero, to determine the average neutron energy causing fission. Simulation results will be discussed in this paper. Finally, new fission yield measurements will be proposed on Caliban and Prospero reactors to strengthen the results of the first experiments. (authors)

Casoli, P.; Authier, N. [CEA, Centre de Valduc, 21120 Is-sur-Tille (France); Laurec, J.; Bauge, E.; Granier, T. [CEA, Centre DIF, 91297 Arpajon (France)

2011-07-01T23:59:59.000Z

74

Science based stockpile stewardship, uncertainty quantification, and fission fragment beams  

SciTech Connect (OSTI)

Stewardship of this nation's nuclear weapons is predicated on developing a fundamental scientific understanding of the physics and chemistry required to describe weapon performance without the need to resort to underground nuclear testing and to predict expected future performance as a result of intended or unintended modifications. In order to construct more reliable models, underground nuclear test data is being reanalyzed in novel ways. The extent to which underground experimental data can be matched with simulations is one measure of the credibility of our capability to predict weapon performance. To improve the interpretation of these experiments with quantified uncertainties, improved nuclear data is required. As an example, the fission yield of a device was often determined by measuring fission products. Conversion of the measured fission products to yield was accomplished through explosion code calculations (models) and a good set of nuclear reaction cross-sections. Because of the unique high-fluence environment of an exploding nuclear weapon, many reactions occurred on radioactive nuclides, for which only theoretically calculated cross-sections are available. Inverse kinematics reactions at CARIBU offer the opportunity to measure cross-sections on unstable neutron-rich fission fragments and thus improve the quality of the nuclear reaction cross-section sets. One of the fission products measured was {sup 95}Zr, the accumulation of all mass 95 fission products of Y, Sr, Rb and Kr (see Fig. 1). Subsequent neutron-induced reactions on these short lived fission products were assumed to cancel out - in other words, the destruction of mass 95 nuclides was more or less equal to the production of mass 95 nuclides. If a {sup 95}Sr was destroyed by an (n,2n) reaction it was also produced by (n,2n) reactions on {sup 96}Sr, for example. However, since these nuclides all have fairly short half-lives (seconds to minutes or even less), no experimental nuclear reaction cross-sections exist, and only theoretically modeled cross-sections are available. Inverse kinematics reactions at CARIBU offer the opportunity, should the beam intensity be sufficient, to measure cross-sections on a few important nuclides in order to benchmark the theoretical calculations and significantly improve the nuclear data. The nuclides in Fig. 1 are prioritized by importance factor and displayed in stoplight colors, green the highest and red the lowest priority.

Stoyer, M A; McNabb, D; Burke, J; Bernstein, L A; Wu, C Y

2009-09-14T23:59:59.000Z

75

Fission Product Data Measured at Los Alamos for Fission Spectrum and Thermal Neutrons on {sup 239}Pu, {sup 235}U, {sup 238}U  

SciTech Connect (OSTI)

We describe measurements of fission product data at Los Alamos that are important for determining the number of fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The fission-spectrum measurements were made using a fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of fission-product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing fission of 400-600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4-1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of fission product yields in different fuel and neutron environments (Q-values) and fission product yields in fission spectrum neutron environments for {sup 99}Mo, {sup 95}Zr, {sup 137}Cs, {sup 140}Ba, {sup 141,143}Ce, and {sup 147}Nd. Modest incident-energy dependence exists for the {sup 147}Nd fission product yield; this is discussed in the context of models for fission that include thermal and dynamical effects. The fission product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying fission products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by {approx}5-7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated fission-spectrum fission product yields that were carried over to the ENDF/B-VII.0 library, except for {sup 99}Mo where the present results are about 4%-relative higher for neutrons incident on {sup 239}Pu and {sup 235}U. Additionally, our results illustrate the importance of representing the incident energy dependence of fission product yields over the fast neutron energy range for high-accuracy work, for example the {sup 147}Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.

Selby, H.D., E-mail: hds@lanl.go [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mac Innes, M.R.; Barr, D.W.; Keksis, A.L.; Meade, R.A.; Burns, C.J.; Chadwick, M.B.; Wallstrom, T.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2010-12-15T23:59:59.000Z

76

Experimental Progress Report--Modernizing the Fission Basis  

SciTech Connect (OSTI)

In 2010 a proposal (Modernizing the Fission Basis) was prepared to 'resolve long standing differences between LANL and LLNL associated with the correct fission basis for analysis of nuclear test data'. Collaboration between LANL/LLNL/TUNL has been formed to implement this program by performing high precision measurements of neutron induced fission product yields as a function of incident neutron energy. This new program benefits from successful previous efforts utilizing mono-energetic neutrons undertaken by this collaboration. The first preliminary experiment in this new program was performed between July 24-31, 2011 at TUNL and had 2 main objectives: (1) demonstrating the capability to measure characteristic {gamma}-rays from specific fission products; (2) studying background effects from room scattered neutrons. In addition, a new dual fission ionization chamber has been designed and manufactured. The production design of the chamber is shown in the picture below. The first feasibility experiment to test this chamber is scheduled at the TUNL Tandem Laboratory from September 19-25, 2011. The dual fission chamber design will allow simultaneous exposure of absolute fission fragment emission rate detectors and the thick fission activation foils, positioned between the two chambers. This document formalizes the earlier experimental report demonstrating the experimental capability to make accurate (< 2 %) precision gamma-ray spectroscopic measurements of the excitation function of high fission product yields of the 239Pu(n,f) reaction (induced by quasimonoenergetic neutrons). A second experiment (9/2011) introduced an compact double-sided fission chamber into the experimental arrangement, and so the relative number of incident neutrons striking the sample foil at each bombarding energy is limited only by statistics. (The number of incident neutrons often limits the experimental accuracy.) Fission chamber operation was so exceptional that 2 more chambers have been fabricated; thus fission foils of different isotopes may be left in place with sample changes. The scope of the measurements is both greatly expanded and the results become vetted. Experiment 2 is not reported here. A continuing experiment has been proposed for February 2012.

Macri, R A

2012-02-17T23:59:59.000Z

77

Realistic fission model and the r-process in neutron star mergers  

SciTech Connect (OSTI)

About half of heavy elements are considered to be produced by the rapid neutron-capture process, r-process. The neutron star merger is one of the viable candidates for the astrophysical site of r-process nucleosynthesis. Nuclear fission reactions play an important role in the r-process of neutron star mergers. However theoretical predictions about fission properties of neutron-rich nuclei have some uncertainties. Especially, their fission fragment distributions are totally unknown and the phenomenologically extrapolated distribution was often applied to nucleosynthesis calculations. In this study, we have carried out r-process nucleosynthesis calculations based upon new theoretical estimates of fission fragment distributions. We discuss the effects on the r-process in neutron star mergers from the nuclear fission of heavy neutron-rich actinide elements. We also discuss how variations in the fission fragment distributions affect the abundance pattern.

Shibagaki, S.; Kajino, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan and National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Chiba, S. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8850 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, IN 46556, U.S.A. and National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2014-05-09T23:59:59.000Z

78

Electron-capture delayed fission properties of {sup 242}Es  

SciTech Connect (OSTI)

Electron-capture delayed fission of {sup 242}Es produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at 87 MeV (on target) was observed to decay with a half-life of 11{+-}3 s, consistent with the reported {alpha}-decay half-life of {sup 242}Es of 16{sub -4}{sup +6} s. The mass-yield distribution of the fission fragments is highly asymmetric. The average pre-neutron emission total kinetic energy of the fragments was measured to be 183{+-}18 MeV. Based on the ratio of the measured number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 242}Cf (100% {alpha} branch), the probability of delayed fission was determined to be 0.006{+-}0.002. This value for the delayed fission probability fits the experimental trend of increasing delayed fission probability with increasing Q value for electron capture. (c) 2000 The American Physical Society.

Shaughnessy, D. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Chemistry Department, University of California, Berkeley, California 94720 (United States); Adams, J. L. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Gregorich, K. E. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Lane, M. R. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Laue, C. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Lee, D. M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); McGrath, C. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Patin, J. B. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Strellis, D. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Sylwester, E. R. [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States) [Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 70-319, Berkeley, California 94720 (United States); Chemistry Department, University of California, Berkeley, California 94720 (United States)] (and others)

2000-04-01T23:59:59.000Z

79

Description of Induced Nuclear Fission with Skyrme Energy Functionals: I. Static Potential Energy Surfaces and Fission Fragment Properties  

E-Print Network [OSTI]

Eighty years after its experimental discovery, a microscopic description of induced nuclear fission based solely on the interactions between neutrons and protons and quantum many-body methods still poses formidable challenges. The goal of this paper is to contribute to the development of a predictive microscopic framework for the accurate calculation of static properties of fission fragments for hot fission and thermal or slow neutrons. To this end, we focus on the 239Pu(n,f) reaction and employ nuclear density functional theory with Skyrme energy densities. Potential energy surfaces are computed at the Hartree-Fock-Bogoliubov approximation with up to five collective variables. We find that the triaxial degree of freedom plays an important role, both near the fission barrier and at scission. The impact of the parameterization of the Skyrme energy density on deformation properties from the ground-state up to scission is also quantified. We introduce a general template for the detailed description of fission fragment properties. It is based on the careful analysis of the scission point, using both advanced topological methods and recently proposed quantum many-body techniques. We conclude that an accurate prediction of fission fragment properties at low incident neutron energies, although technologically demanding, should be within the reach of current nuclear density functional theory.

N. Schunck; D. Duke; H. Carr; A. Knoll

2014-09-17T23:59:59.000Z

80

Delayed neutron yield from fast neutron induced fission of sup 2 sup 3 sup 8 U  

E-Print Network [OSTI]

The measurements of the total delayed neutron yield from fast neutron induced fission of sup 2 sup 3 sup 8 U were made. The experimental method based on the periodic irradiation of the fissionable sample by neutrons from a suitable nuclear reaction had been employed. The preliminary results on the energy dependence of the total delayed neutron yield from fission of sup 2 sup 3 sup 8 U are obtained. According to the comparison of experimental data with our prediction based on correlation properties of delayed neutron characteristics, it is concluded that the value of the total delayed neutron yield near the threshold of (n,f) reaction is not a constant.

Piksaikin, V M; Isaev, S G; Kazakov, L E; Roshchenko, V A; Tertytchnyi, R G

2001-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Post-scission fission theory: Neutron emission in fission  

SciTech Connect (OSTI)

A survey of theoretical representations of two of the observables in neutron emission in fission is given, namely, the prompt fission neutron spectrum N (E) and the average prompt neutron multiplicity {bar {nu}}{sub p}. Early representations of the two observables are presented and their deficiencies are discussed. This is followed by summaries and examples of recent theoretical models for the calculation of these quantities. Emphasis is placed upon the predictability and accuracy of the recent models. In particular, the dependencies of N (E) and {bar {nu}}{sub p} upon the fissioning nucleus and its excitation energy are treated. Recent work in the calculation of the prompt fission neutron spectrum matrix N (E, E{sub n}), where E{sub n} is the energy of the neutron inducing fission, is then discussed. Concluding remarks address the current status of our ability to calculate these observables with confidence, the direction of future theoretical efforts, and limitations to current (and future) approaches.

Madland, D.G.

1997-11-01T23:59:59.000Z

82

Cross sections and barriers for nuclear fission induced by high-energy nucleons  

SciTech Connect (OSTI)

The cross sections for the fission of {sup 232}Th, {sup 235,238}U, {sup 237}Np, and {sup 239}Pu target nuclei that was induced by 20- to 1000-MeV neutrons and protons were calculated. The respective calculations were based on the multiconfiguration-fission (MCFx) model, which was used to describe three basic stages of the interaction of high-energy nucleons with nuclei: direct processes (intranuclear cascade), equilibration of the emerging compound system, and the decay of the compound nucleus (statistical model). Fission barriers were calculated within the microscopic approach for isotopic chains formed by 15 to 20 nuclei of the required elements. The calculated fission cross sections were compared with available experimental data. It was shown that the input data set and the theoretical model used made it possible to predict satisfactorily cross section for nuclear fission induced by 20- to 1000-MeV nucleons.

Grudzevich, O. T., E-mail: ogrudzevich@ippe.ru [Leipunsky Institute for Physics and Power Engineering (Russian Federation); Yavshits, S. G. [Khlopin Radium Institute (Russian Federation)] [Khlopin Radium Institute (Russian Federation)

2013-03-15T23:59:59.000Z

83

Fission throughout the periodic table  

SciTech Connect (OSTI)

The dualistic view of fission and evaporation as two distinct compound nucleus processes is substituted with a unified view in which fission, complex fragment emission, and light particle evaporation are seen as different aspects of a single process. 47 refs., 22 figs.

Moretto, L.G.; Wozniak, G.J.

1989-04-01T23:59:59.000Z

84

Decay Properties of {sup 266}Bh and {sup 262}Db Produced in the {sup 248}Cm+{sup 23}Na Reaction - Further Confirmation of the {sup 278}113 Decay Chain  

SciTech Connect (OSTI)

Decay properties of an isotope {sup 266}Bh and its daughter nucleus {sup 262}Db produced by the {sup 248}Cm({sup 23}Na,5n) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. {sup 266}Bh was clearly identified from the correlation of the known nuclide, {sup 262}Db. The obtained decay properties of {sup 266}Bh and {sup 262}Db are consistent with those observed in the {sup 278}113 chain by RIKEN collaboration, which provided further confirmation of the discovery of {sup 278}113.

Morita, K.; Morimoto, K.; Kaji, D.; Haba, H.; Ozeki, K.; Kudou, Y.; Yoneda, A.; Ichikawa, T.; Katori, K.; Yoshida, A. [RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Sato, N. [RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Department of Physics, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan); Sumita, T. [RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510 (Japan); Fujimori, Y.; Tokanai, F. [Department of Physics, Yamagata University, Yamagata 990-8560 (Japan); Goto, S. [Center for Instrumental Analysis, Niigata University, Ikarashi, Nishi-ku, Niigata 950-2181 (Japan); Ideguchi, E. [Center for Nuclear Study, University of Tokyo, Wako, Saitama 351-0198 (Japan); Kasamatsu, Y.; Koura, H.; Tsukada, K. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Komori, Y. [Department of Chemistry, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2010-06-01T23:59:59.000Z

85

Electron-capture delayed fission in {sup 246}Es  

SciTech Connect (OSTI)

We have extended our systematic study of electron-capture delayed fission (ECDF) in neutron-deficient isotopes to {sup 246}Es. The {sup 246}Es was produced at the 88 Inch Cyclotron at Lawrence Berkeley National Laboratory via the {sup 249}Cf(p,xn){sup 250-x}Es reaction with 37 MeV protons. There were 19 {sup 249}Cf targets used simultaneously in our light ion multiple (LIM) target system. Alpha particles and fission fragments were detected in our rotating wheel system. In some experiments, TTA extractions were performed to remove interfering activities. The chemically separated samples were positioned between a solid-state particle detector and two x-rays detectors. This configuration enabled us to look for fissions in coincidence with K x-rays following electron-capture. Our measured production cross section of 13 {+-} 5 {mu}b for {sup 246}Es was much lower than the cross section predicted by a neutron evaporation code. The probability of delayed fission was determined from the number of x-ray/fission coincidences measured.

Shaughnessy, D.A.; Gregorich, K.E.; Hendricks, M.B.; Lane, M.R. [Lawrence Berkeley National Lab., CA (United States)] [and others

1997-12-31T23:59:59.000Z

86

Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory  

SciTech Connect (OSTI)

Background: The reactions with the neutron-rich 48Ca beam and actinide targets resulted in the detection of new superheavy (SH) nuclides with Z=104 118. The unambiguous identification of the new isotopes, however, still poses a problem because their -decay chains terminate by spontaneous fission (SF) before reaching the known region of the nuclear chart. The understanding of the competition between -decay and SF channels in SH nuclei is, therefore, of crucial importance for our ability to map the SH region and to assess its extent.

Purpose: We perform self-consistent calculations of the competing decay modes of even-even SH isotopes with 108 Z 126 and 148 N 188.

Methods: We use the state-of-the-art computational framework based on self-consistent symmetry-unrestricted nuclear density functional theory capable of describing the competition between nuclear attraction and electrostatic repulsion. We apply the SkM* Skyrme energy density functional. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov (HFB) approach. This paper constitutes a systematic self-consistent study of spontaneous fission in the SH region, carried out at a full HFB level, that simultaneously takes into account both triaxiality and reflection asymmetry.

Results: Breaking axial symmetry and parity turns out to be crucial for a realistic estimate of collective action; it results in lowering SF lifetimes by more than 7 orders of magnitude in some cases. We predict two competing SF modes: reflection symmetric modes and reflection asymmetric modes.

Conclusions: The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by 280Hs, 284Fl, and 118284Uuo that separates the regions of SH nuclei synthesized in cold-fusion and hot-fusion reactions. The region of long-lived SH nuclei is expected to be centered on 294Ds with a total half-life of 1.5 days. Our survey provides a solid benchmark for the future improvements of self-consistent SF calculations in the region of SH nuclei.

Staszczak, A, [UTK/ORNL/Inst. Physics, Maria Curie-Sklodowska University, Poland; Baran, A. [UTK/ORNL/Inst. Physics, Maria Curie-Sklodowska University, Poland; Nazarewicz, Witold [UTK/ORNL/University of Warsaw

2013-01-01T23:59:59.000Z

87

Relative yields of U-235 fission products measured in a high level radioactive sludge at Savannah River Site  

SciTech Connect (OSTI)

This paper presents measurements of the concentrations of 42 of the long-lived U-235 fission products in a high-level radioactive waste sludge stored at Savannah River Site. The 42 fision products make up 98% of the waste sludge. We used inductively coupled plasma-mass spectroscopy for the analysis. The relative yields for most of the fission products are in complete agreement with the known relative yields for the beta decay chains of the two asymmetric branches of the slow neutron fission of U-235. Disagreements can be reconciled based on the chemistry of the fission products in the caustic waste sludges, the neutron fluences in SRS reactors, or interferences in the ICP-MS analyses. This paper presents measurements of the concentrations of 42 (98%) of the long-lived U-235 fission products in a high-level radioactive waste sludge stored at the Savannah River Site. We analyzed the sludge with inductively coupled plasma-mass spectroscopy. The relative yields for most of the fission products agree completely with the known relative vields for the beta decay chains of the two asymmetric: branches of the slow neutron fission of U-235. The chemistry of the fission products in the caustic waste sludges, the neutron fluences in SRS reactors, or interferences in the ICP-MS analyses explain the differences in the measured and calculated results.

Bibler, N.E.; Coleman, C.J. [Westinghouse Savannah River Co., Aiken, SC (United States); Kinard, W.F. [Charleston Coll., SC (United States). Dept. of Chemistry

1992-10-01T23:59:59.000Z

88

Relative yields of U-235 fission products measured in a high level radioactive sludge at Savannah River Site  

SciTech Connect (OSTI)

This paper presents measurements of the concentrations of 42 of the long-lived U-235 fission products in a high-level radioactive waste sludge stored at Savannah River Site. The 42 fision products make up 98% of the waste sludge. We used inductively coupled plasma-mass spectroscopy for the analysis. The relative yields for most of the fission products are in complete agreement with the known relative yields for the beta decay chains of the two asymmetric branches of the slow neutron fission of U-235. Disagreements can be reconciled based on the chemistry of the fission products in the caustic waste sludges, the neutron fluences in SRS reactors, or interferences in the ICP-MS analyses. This paper presents measurements of the concentrations of 42 (98%) of the long-lived U-235 fission products in a high-level radioactive waste sludge stored at the Savannah River Site. We analyzed the sludge with inductively coupled plasma-mass spectroscopy. The relative yields for most of the fission products agree completely with the known relative vields for the beta decay chains of the two asymmetric: branches of the slow neutron fission of U-235. The chemistry of the fission products in the caustic waste sludges, the neutron fluences in SRS reactors, or interferences in the ICP-MS analyses explain the differences in the measured and calculated results.

Bibler, N.E.; Coleman, C.J. (Westinghouse Savannah River Co., Aiken, SC (United States)); Kinard, W.F. (Charleston Coll., SC (United States). Dept. of Chemistry)

1992-01-01T23:59:59.000Z

89

A brief history of the Delayed'' discovery of nuclear fission  

SciTech Connect (OSTI)

This year marks the Fiftieth Anniversary of the discovery of Nuclear Fission. In the early 1930's, the neutron was discovered, followed by the discovery of artificial radioactivity and then the use of the neutron to produce artificial radioactivity. The first experiments resulting in the fission of uranium took place in 1934. A paper which speculated on fission as an explanation was almost immediately published, yet no one took it seriously not even the author herself. Why did it take an additional five years before anyone realized what had occurred This is an abnormally long time in a period when discoveries, particularly in nuclear physics, seemed to be almost a daily occurrence. The events which led up to the discovery are recounted, with an attempt made to put them into their historical perspective. The role played by Mendeleev's Periodic Table, the role of the natural radioactive decay chain of uranium, the discovery of protactinium, the apparent discovery of masurium (technetium) and a speculation on the reason why Irene Curie may have missed the discovery of nuclear fission will all be discussed. 43 refs.

Holden, N.E.

1989-08-01T23:59:59.000Z

90

Measurement and Analysis of Fission Rates in a Spherical Mockup of Uranium and Polyethylene  

E-Print Network [OSTI]

Measurements of the reaction rate distribution were carried out using two kinds of Plate Micro Fission Chamber(PMFC). The first is a depleted uranium chamber and the second an enriched uranium chamber. The material in the depleted uranium chamber is strictly the same as the material in the uranium assembly. With the equation solution to conduct the isotope contribution correction, the fission rate of 238U and 235U were obtained from the fission rate of depleted uranium and enriched uranium. And then, the fission count of 238U and 235U in an individual uranium shell was obtained. In this work, MCNP5 and continuous energy cross sections ENDF/BV.0 were used for the analysis of fission rate distribution and fission count. The calculated results were compared with the experimental ones. The calculation of fission rate of DU and EU were found to agree with the measured ones within 10% except at the positions in polyethylene region and the two positions near the outer surface. Beacause the fission chamber was not co...

Tong-Hua, Zhu; Xin-Xin, Lu; Rong, Liu; Zi-Jie, Han; Li, Jiang; Mei, Wang

2013-01-01T23:59:59.000Z

91

A dynamical treatment of isobaric widths in fission : An example of frozen quantal fluctuations  

E-Print Network [OSTI]

in the case of low energy nuclear fission since the excitation energies involved at scission are only to heavy ion reactions is discussed. Tome 41 No 3 ler FEVRIER 1980 LE JOURNAL DE PHYSIQUE - LETTRES has been recently underlined in heavy ion reactions [1], [2], [3], [4]. Experimentally it appears [1

Boyer, Edmond

92

Fission product solvent extraction  

SciTech Connect (OSTI)

Two main objectives concerning removal of fission products from high-level tank wastes will be accomplished in this project. The first objective entails the development of an acid-side Cs solvent-extraction (SX) process applicable to remediation of the sodium-bearing waste (SBW) and dissolved calcine waste (DCW) at INEEL. The second objective is to develop alkaline-side SX processes for the combined removal of Tc, Cs, and possibly Sr and for individual separation of Tc (alone or together with Sr) and Cs. These alkaline-side processes apply to tank wastes stored at Hanford, Savannah River, and Oak Ridge. This work exploits the useful properties of crown ethers and calixarenes and has shown that such compounds may be economically adapted to practical processing conditions. Potential benefits for both acid- and alkaline-side processing include order-of-magnitude concentration factors, high rejection of bulk sodium and potassium salts, and stripping with dilute (typically 10 mM) nitric acid. These benefits minimize the subsequent burden on the very expensive vitrification and storage of the high-activity waste. In the case of the SRTALK process for Tc extraction as pertechnetate anion from alkaline waste, such benefits have now been proven at the scale of a 12-stage flowsheet tested in 2-cm centrifugal contactors with a Hanford supernatant waste simulant. SRTALK employs a crown ether in a TBP-modified aliphatic kerosene diluent, is economically competitive with other applicable separation processes being considered, and has been successfully tested in batch extraction of actual Hanford double-shell slurry feed (DSSF).

Moyer, B.A.; Bonnesen, P.V.; Sachleben, R.A. [and others

1998-02-01T23:59:59.000Z

93

Control system for a small fission reactor  

DOE Patents [OSTI]

A system for controlling the reactivity of a small fission reactor includes an elongated, flexible hollow tube in the general form of a helical coiled spring axially positioned around and outside of the reactor vessel in an annular space between the reactor vessel and a surrounding cylindrical-shaped neutron reflector. A neutron absorbing material is provided within the hollow tube with the rate of the reaction controlled by the extension and compression of the hollow tube, e.g., extension of the tube increases reactivity while its compression reduces reactivity, in varying the amount of neutron absorbing material disposed between the reactor vessel and the neutron reflector. Conventional mechanical displacement means may be employed to control the coil density of the hollow tube as desired.

Burelbach, J.P.; Kann, W.J.; Saiveau, J.G.

1985-02-08T23:59:59.000Z

94

Recent MELCOR and VICTORIA Fission Product Research at the NRC  

SciTech Connect (OSTI)

The MELCOR and VICTORIA severe accident analysis codes, which were developed at Sandia National Laboratories for the U. S. Nuclear Regulatory Commission, are designed to estimate fission product releases during nuclear reactor accidents in light water reactors. MELCOR is an integrated plant-assessment code that models the key phenomena in adequate detail for risk-assessment purposes. VICTORIA is a more specialized fission- product code that provides detailed modeling of chemical reactions and aerosol processes under the high-temperature conditions encountered in the reactor coolant system during a severe reactor accident. This paper focuses on recent enhancements and assessments of the two codes in the area of fission product chemistry modeling. Recently, a model for iodine chemistry in aqueous pools in the containment building was incorporated into the MELCOR code. The model calculates dissolution of iodine into the pool and releases of organic and inorganic iodine vapors from the pool into the containment atmosphere. The main purpose of this model is to evaluate the effect of long-term revolatilization of dissolved iodine. Inputs to the model include dose rate in the pool, the amount of chloride-containing polymer, such as Hypalon, and the amount of buffering agents in the containment. Model predictions are compared against the Radioiodine Test Facility (RTF) experiments conduced by Atomic Energy of Canada Limited (AECL), specifically International Standard Problem 41. Improvements to VICTORIA's chemical reactions models were implemented as a result of recommendations from a peer review of VICTORIA that was completed last year. Specifically, an option is now included to model aerosols and deposited fission products as three condensed phases in addition to the original option of a single condensed phase. The three-condensed-phase model results in somewhat higher predicted fission product volatilities than does the single-condensed-phase model. Modeling of U02 thermochemistry was also improved, and results in better prediction of vaporization of uranium from fuel, which can react with released fission products to affect their volatility. This model also improves the prediction of fission product release rates from fuel. Finally, recent comparisons of MELCOR and VICTORIA with International Standard Problem 40 (STORM) data are presented. These comparisons focus on predicted therrnophoretic deposition, which is the dominant deposition mechanism. Sensitivity studies were performed with the codes to examine experimental and modeling uncertainties.

Bixler, N.E.; Cole, R.K.; Gauntt, R.O.; Schaperow, J.H.; Young, M.F.

1999-01-21T23:59:59.000Z

95

Process for treating fission waste. [Patent application  

DOE Patents [OSTI]

A method is described for the treatment of fission waste. A glass forming agent, a metal oxide, and a reducing agent are mixed with the fission waste and the mixture is heated. After melting, the mixture separates into a glass phase and a metal phase. The glass phase may be used to safely store the fission waste, while the metal phase contains noble metals recovered from the fission waste.

Rohrmann, C.A.; Wick, O.J.

1981-11-17T23:59:59.000Z

96

Neutronics for critical fission reactors and subcritical fission in hybrids  

SciTech Connect (OSTI)

The requirements of future innovative nuclear fuel cycles will focus on safety, sustainability and radioactive waste minimization. Critical fast neutron reactors and sub-critical, external source driven systems (accelerator driven and fusion-fission hybrids) have a potential role to meet these requirements in view of their physics characteristics. This paper provides a short introduction to these features.

Salvatores, Massimo [CEA-Cadarache, DEN-Dir, Bat. 101, St-Paul-Lez-Durance 13108 (France)

2012-06-19T23:59:59.000Z

97

Space Fission System Test Effectiveness  

SciTech Connect (OSTI)

Space fission technology has the potential to enable rapid access to any point in the solar system. If fission propulsion systems are to be developed to their full potential, however, near-term customers need to be identified and initial fission systems successfully developed, launched, and utilized. One key to successful utilization is to develop reactor designs that are highly testable. Testable reactor designs have a much higher probability of being successfully converted from paper concepts to working space hardware than do designs which are difficult or impossible to realistically test. ''Test Effectiveness'' is one measure of the ability to realistically test a space reactor system. The objective of this paper is to discuss test effectiveness as applied to the design, development, flight qualification, and acceptance testing of space fission systems. The ability to perform highly effective testing would be particularly important to the success of any near-term mission, such as NASA's Jupiter Icy Moons Orbiter, the first mission under study within NASA's Project Prometheus, the Nuclear Systems Program.

Houts, Mike [Los Alamos National Laboratory, MS-K575, Los Alamos, NM 87545 (United States); Schmidt, Glen L. [New Mexico Tech, Institute for Engineering Research and Applications, 901 University Blvd SE, Albuquerque, NM 87109-4339 (United States); Van Dyke, Melissa; Godfroy, Tom; Martin, James; Bragg-Sitton, Shannon; Dickens, Ricky; Salvail, Pat; Harper, Roger [NASA MSFC, TD40, Marshall Space Flight Center, AL, 35812 (United States)

2004-02-04T23:59:59.000Z

98

He-jet system to study short-lived fission-product nuclei at LAMPF  

SciTech Connect (OSTI)

Experiments have been performed at LAMPF which demonstrate the feasibility of utilizing a He-jet system to transport fission products to an on-line mass separator from a target chamber mounted in the 800-MeV, >600..mu..A main proton beam. Activities of essentially all elements produced are transported with about 60% absolute efficiency, both for fission reactions and spallation reactions. Transport times are short enough to allow study of activities with half-lives as short as 300 ms. Technical features and scientific possibilities of the system are presented.

Talbert, W.L. Jr.; Bunker, M.E.; Starner, J.W.

1983-01-01T23:59:59.000Z

99

Status of fission yield evaluations  

SciTech Connect (OSTI)

Very few yield compilations are also evaluations, and very few contain an extensive global library of measured data and extensive models for unmeasured data. The earlier U.K. evaluations and US evaluations were comparable up to the retirements of the primary evaluators. Only the effort in the US has been continued and expanded. The previous U.K. evaluations have been published. In this paper we summarize the current status of the US evaluation, philosophy, and various integral yield tests for 34 fissioning nuclides at one or more neutron incident energies and/or for spontaneous fission. Currently there are 50 yield sets and for each we have independent and cumulative yields and uncertainties for approximately 1100 fission products. When finalized, the recommended data will become part of the next version of the US Evaluated Nuclear Data File (ENDF/B-VI). The complete set of data, including the basic input of measured yields, will be issued as a sequel to the General Electric evaluation reports (better known by the authors' names: Rider - or earlier - Meek and Rider). 16 references.

England, T.R.; Rider, B.F.

1983-01-01T23:59:59.000Z

100

Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS  

SciTech Connect (OSTI)

Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS have been conducted. In this work, fission cross section resulted from MCNP6 prediction will be compared with result from TALYS calculation. MCNP6 with its event generator CEM03.03 and LAQGSM03.03 have been validated and verified for several intermediate and heavy nuclides fission reaction data and also has a good agreement with experimental data for fission reaction that induced by photons, pions, and nucleons at energy from several ten of MeV to about 1 TeV. The calculation that induced within TALYS will be focused mainly to several hundred MeV for actinide and sub-actinide nuclides and will be compared with MCNP6 code and several experimental data from other evaluator.

Perkasa, Y. S. [Department of Physics, Sunan Gunung Djati State Islamic University Bandung, Jl. A.H Nasution No. 105 Cibiru, Bandung (Indonesia); Waris, A., E-mail: awaris@fi.itb.ac.id; Kurniadi, R., E-mail: awaris@fi.itb.ac.id; Su'ud, Z., E-mail: awaris@fi.itb.ac.id [Nuclear Physics and Biophysics Research Division, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa No. 10 Bandung 40132 (Indonesia)

2014-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Study of heavy ion induced fission fragment angular and mass distribution at near and sub-coulomb barrier energies  

E-Print Network [OSTI]

The thesis presents investigations on the angular and mass distribution of fission fragments on heavy ion induced fission reactions. The present investigations address current issues in heavy ion induced fission reactions like finding the optimum entrance channel for the synthesis of super heavy elements (SHE). A double arm time of flight spectrometer over long flight path was used to measure the precise masses of complementary fission fragments. Necessary large area position sensitive gas detectors, the method of experiments and data analysis were developed. The first string of measurements were for a spherical target (209^Bi) with oxygen and fluorine projectiles. The next series of experiments were done using a deformed target (232^Th) with fluorine, oxygen and carbon projectiles.

T. K. Ghosh

2005-08-10T23:59:59.000Z

102

Fission barriers and half-lives  

SciTech Connect (OSTI)

We briefly review the development of theoretical models for the calculation of fission barriers and half-lives. We focus on how results of actual calculations in a unified macroscopic-microscopic approach provide an interpretation of the mechanisms behind some of the large number of phenomena observed in fission. As instructive examples we choose studies of the rapidly varying fission properties of elements at the end of the periodic system. 31 refs., 10 figs.

Moeller, P.; Nix, J.R.; Swiatecki, W.J.

1989-01-01T23:59:59.000Z

103

Proton-induced fission of actinides at energies 26.5 and 62.9 MeV--Theoretical interpretation  

SciTech Connect (OSTI)

Fission properties of proton-induced fission on {sup 232}Th, {sup 237}Np, {sup 238}U, {sup 239}Pu and {sup 241}Am targets, measured at the Louvain-la-Neuve cyclotron facility at proton energies of 26.5 and 62.9 MeV, are compared with the predictions of the state-of-the-art nuclear reaction code TALYS. The sensitivity of the calculations to the input parameters of the code and possible improvements are discussed.

Demetriou, P. [Institute of Nuclear Physics, NCSR 'Demokritos', 15310 Athens (Greece); Keutgen, Th.; Prieels, R.; El Masri, Y. [FNRS and Institut de Physique Nucleaire, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium)

2011-10-28T23:59:59.000Z

104

Monitoring system for a liquid-cooled nuclear fission reactor  

DOE Patents [OSTI]

A monitoring system for detecting changes in the liquid levels in various regions of a water-cooled nuclear power reactor, viz., in the downcomer, in the core, in the inlet and outlet plenums, at the head, and elsewhere; and also for detecting changes in the density of the liquid in these regions. A plurality of gamma radiation detectors are used, arranged vertically along the outside of the reactor vessel, and collimator means for each detector limits the gamma-radiation it receives as emitting from only isolated regions of the vessel. Excess neutrons produced by the fission reaction will be captured by the water coolant, by the steel reactor walls, or by the fuel or control structures in the vessel. Neutron capture by steel generates gamma radiation having an energy level of the order of 5-12 MeV, whereas neutron capture by water provides an energy level of approximately 2.2 MeV, and neutron capture by the fission fuel or its cladding provides an energy level of 1 MeV or less. The intensity of neutron capture thus changes significantly at any water-metal interface. Comparative analysis of adjacent gamma detectors senses changes from the normal condition with liquid coolant present to advise of changes in the presence and/or density of the coolant at these specific regions. The gamma detectors can also sense fission-product gas accumulation at the reactor head to advise of a failure of fuel-pin cladding.

DeVolpi, Alexander (Bolingbrook, IL)

1987-01-01T23:59:59.000Z

105

Description of Induced Nuclear Fission with Skyrme Energy Functionals: II. Finite Temperature Effects  

E-Print Network [OSTI]

Understanding the mechanisms of induced nuclear fission for a broad range of neutron energies could help resolve fundamental science issues, such as the formation of elements in the universe, but could have also a large impact on societal applications in energy production or nuclear waste management. The goal of this paper is to set up the foundations of a microscopic theory to study the static aspects of induced fission as a function of the excitation energy of the incident neutron, from thermal to fast neutrons. To account for the high excitation energy of the compound nucleus, we employ a statistical approach based on finite-temperature nuclear density functional theory with Skyrme energy densities, which we benchmark on the 239 Pu(n,f) reaction. We compute the evolution of the least-energy fission pathway across multidimensional potential energy surfaces with up to five collective variables as a function of the nuclear temperature, and predict the evolution of both the inner and outer fission barriers as a function of the excitation energy of the compound nucleus. We show that the coupling to the continuum induced by the finite temperature is negligible in the range of neutron energies relevant for many applications of neutron-induced fission. We prove that the concept of quantum localization introduced recently can be extended to T > 0, and we apply the method to study the interaction energy and total kinetic energy of fission fragments as a function of the temperature for the most probable fission. While large uncertainties in theoretical modeling remain, we conclude that finite-temperature nuclear density functional may provide a useful framework to obtain accurate predictions of fission fragment properties.

N. Schunck; D. Duke; H. Carr

2015-01-23T23:59:59.000Z

106

Fission fragment excited laser system  

DOE Patents [OSTI]

A laser system and method for exciting lasing action in a molecular gas lasing medium which includes cooling the lasing medium to a temperature below about 150 K and injecting fission fragments through the lasing medium so as to preferentially excite low lying vibrational levels of the medium and to cause population inversions therein. The cooled gas lasing medium should have a mass areal density of about 5 .times. 10.sup.-.sup.3 grams/square centimeter, relaxation times of greater than 50 microseconds, and a broad range of excitable vibrational levels which are excitable by molecular collisions.

McArthur, David A. (Albuquerque, NM); Tollefsrud, Philip B. (Albuquerque, NM)

1976-01-01T23:59:59.000Z

107

Control system for a small fission reactor  

DOE Patents [OSTI]

A system for controlling the reactivity of a small fission reactor includes an elongated, flexible hollow tube in the general form of a helical coiled spring axially positioned around and outside of the reactor vessel in an annular space between the reactor vessel and a surrounding cylindrical-shaped neutron reflector. A neutron absorbing material is provided within the hollow tube with the rate of the reaction controlled by the extension and compression of the hollow tube, e.g., extension of the tube increases reactivity while its compression reduces reactivity, in varying the amount of neutron absorbing material disposed between the reactor vessel and the neutron reflector. Conventional mechanical displacement means may be employed to control the coil density of the hollow tube as desired. In another embodiment, a plurality of flexible hollow tubes each containing a neutron absorber are positioned adjacent to one another in spaced relation around the periphery of the reactor vessel and inside the outer neutron reflector with reactivity controlled by the extension and compression of all or some of the coiled hollow tubes. Yet another embodiment of the invention envisions the neutron reflector in the form of an expandable coil spring positioned in an annular space between the reactor vessel and an outer neutron absorbing structure for controlling the neutron flux reflected back into the reactor vessel.

Burelbach, James P. (Glen Ellyn, IL); Kann, William J. (Park Ridge, IL); Saiveau, James G. (Hickory Hills, IL)

1986-01-01T23:59:59.000Z

108

Fission-suppressed fusion breeder on the thorium cycle and nonproliferation  

SciTech Connect (OSTI)

Fusion reactors could be designed to breed fissile material while suppressing fissioning thereby enhancing safety. The produced fuel could be used to startup and makeup fuel for fission reactors. Each fusion reaction can produce typically 0.6 fissile atoms and release about 1.6 times the 14 MeV neutron's energy in the blanket in the fission-suppressed design. This production rate is 2660 kg/1000 MW of fusion power for a year. The revenues would be doubled from such a plant by selling fuel at a price of 60/g and electricity at $0.05/kWh for Q=P{sub fusion}/P{sub input}=4. Fusion reactors could be designed to destroy fission wastes by transmutation and fissioning but this is not a natural use of fusion whereas it is a designed use of fission reactors. Fusion could supply makeup fuel to fission reactors that were dedicated to fissioning wastes with some of their neutrons. The design for safety and heat removal and other items is already accomplished with fission reactors. Whereas fusion reactors have geometry that compromises safety with a complex and thin wall separating the fusion zone from the blanket zone where wastes could be destroyed. Nonproliferation can be enhanced by mixing {sup 233}U with {sup 238}U. Also nonproliferation is enhanced in typical fission-suppressed designs by generating up to 0.05 {sup 232}U atoms for each {sup 233}U atom produced from thorium, about twice the IAEA standards of 'reduced protection' or 'self protection.' With 2.4%{sup 232}U, high explosive material is predicted to degrade owing to ionizing radiation after a little over 1/2 year and the heat rate is 77 W just after separation and climbs to over 600 W ten years later. The fissile material can be used to fuel most any fission reactor but is especially appropriate for molten salt reactors (MSR) also called liquid fluoride thorium reactors (LFTR) because of the molten fuel does not need hands on fabrication and handling.

Moir, R. W. [Vallecitos Molten Salt Research, 607 E. Vallecitos Rd., Livermore, CA 94550 925-447-8804 (United States)

2012-06-19T23:59:59.000Z

109

Why Supply Chain  

E-Print Network [OSTI]

Why supply chain explains the importance of supply chains. It includes an introduction to ERP as designed by SAP.

Datta, Shoumen

2000-01-01T23:59:59.000Z

110

Options for Affordable Fission Surface Power Systems  

SciTech Connect (OSTI)

Fission surface power systems could provide abundant power anywhere on the surface of the moon or Mars. Locations could include permanently shaded regions on the moon and high latitudes on Mars. To be fully utilized, however, fission surface power systems must be safe, have adequate performance, and be affordable. This paper discusses options for the design and development of such systems. (authors)

Houts, Mike; Gaddis, Steve; Porter, Ron; Van Dyke, Melissa; Martin, Jim; Godfroy, Tom; Bragg-Sitton, Shannon; Garber, Anne; Pearson, Boise [NASA Marshall Space Flight Center, VP31, MSFC, AL 35812 (United States)

2006-07-01T23:59:59.000Z

111

Sleeve reaction chamber system  

DOE Patents [OSTI]

A chemical reaction chamber system that combines devices such as doped polysilicon for heating, bulk silicon for convective cooling, and thermoelectric (TE) coolers to augment the heating and cooling rates of the reaction chamber or chambers. In addition the system includes non-silicon-based reaction chambers such as any high thermal conductivity material used in combination with a thermoelectric cooling mechanism (i.e., Peltier device). The heat contained in the thermally conductive part of the system can be used/reused to heat the device, thereby conserving energy and expediting the heating/cooling rates. The system combines a micromachined silicon reaction chamber, for example, with an additional module/device for augmented heating/cooling using the Peltier effect. This additional module is particularly useful in extreme environments (very hot or extremely cold) where augmented heating/cooling would be useful to speed up the thermal cycling rates. The chemical reaction chamber system has various applications for synthesis or processing of organic, inorganic, or biochemical reactions, including the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction.

Northrup, M. Allen (Berkeley, CA); Beeman, Barton V. (San Mateo, CA); Benett, William J. (Livermore, CA); Hadley, Dean R. (Manteca, CA); Landre, Phoebe (Livermore, CA); Lehew, Stacy L. (Livermore, CA); Krulevitch, Peter A. (Pleasanton, CA)

2009-08-25T23:59:59.000Z

112

Theoretical Description of the Fission Process  

SciTech Connect (OSTI)

Advanced theoretical methods and high-performance computers may finally unlock the secrets of nuclear fission, a fundamental nuclear decay that is of great relevance to society. In this work, we studied the phenomenon of spontaneous fission using the symmetry-unrestricted nuclear density functional theory (DFT). Our results show that many observed properties of fissioning nuclei can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. From the calculated collective potential and collective mass, we estimated spontaneous fission half-lives, and good agreement with experimental data was found. We also predicted a new phenomenon of trimodal spontaneous fission for some transfermium isotopes. Our calculations demonstrate that fission barriers of excited superheavy nuclei vary rapidly with particle number, pointing to the importance of shell effects even at large excitation energies. The results are consistent with recent experiments where superheavy elements were created by bombarding an actinide target with 48-calcium; yet even at high excitation energies, sizable fission barriers remained. Not only does this reveal clues about the conditions for creating new elements, it also provides a wider context for understanding other types of fission. Understanding of the fission process is crucial for many areas of science and technology. Fission governs existence of many transuranium elements, including the predicted long-lived superheavy species. In nuclear astrophysics, fission influences the formation of heavy elements on the final stages of the r-process in a very high neutron density environment. Fission applications are numerous. Improved understanding of the fission process will enable scientists to enhance the safety and reliability of the nation’s nuclear stockpile and nuclear reactors. The deployment of a fleet of safe and efficient advanced reactors, which will also minimize radiotoxic waste and be proliferation-resistant, is a goal for the advanced nuclear fuel cycles program. While in the past the design, construction, and operation of reactors were supported through empirical trials, this new phase in nuclear energy production is expected to heavily rely on advanced modeling and simulation capabilities.

Witold Nazarewicz

2009-10-25T23:59:59.000Z

113

Improved Calculation of Thermal Fission Energy  

E-Print Network [OSTI]

Thermal fission energy is one of the basic parameters needed in the calculation of antineutrino flux for reactor neutrino experiments. It is useful to improve the precision of the thermal fission energy calculation for current and future reactor neutrino experiments, which are aimed at more precise determination of neutrino oscillation parameters. In this article, we give new values for thermal fission energies of some common thermal reactor fuel iso-topes, with improvements on two aspects. One is more recent input data acquired from updated nuclear databases. The other, which is unprecedented, is a consideration of the production yields of fission fragments from both thermal and fast incident neutrons for each of the four main fuel isotopes. The change in calculated antineutrino flux due to the new values of thermal fission energy is about 0.33%, and the uncertainties of the new values are about 30% smaller.

Ma, X B; Wang, L Z; Chen, Y X; Cao, J

2013-01-01T23:59:59.000Z

114

Superfluid dynamics of 258Fm fission  

E-Print Network [OSTI]

Theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The slow, mostly adiabatic motion through the fission barrier is followed by a fast, non-adiabatic descent of the potential between the fragments. The latter stage is essentially unexplored. However, it is crucial as it generates most of the excitation energy in the fragments. The superfluid dynamics in the latter stage of fission is obtained with the time-dependent Hartree-Fock theory including BCS dynamical pairing correlations. The fission modes of the 258Fm nucleus are studied. The resulting fission fragment characteristics show a good agreement with experimental data. Quantum shell effects are shown to play a crucial role in the dynamics and formation of the fragments. The importance of quantum fluctuations beyond the independent particle/quasi-particle picture is underlined and qualitatively studied.

Guillaume Scamps; Cédric Simenel; Denis Lacroix

2015-01-15T23:59:59.000Z

115

Superfluid dynamics of 258Fm fission  

E-Print Network [OSTI]

Theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The slow, mostly adiabatic motion through the fission barrier is followed by a fast, non-adiabatic descent of the potential between the fragments. The latter stage is essentially unexplored. However, it is crucial as it generates most of the excitation energy in the fragments. The superfluid dynamics in the latter stage of fission is obtained with the time-dependent Hartree-Fock theory including BCS dynamical pairing correlations. The fission modes of the 258Fm nucleus are studied. The resulting fission fragment characteristics show a good agreement with experimental data. Quantum shell effects are shown to play a crucial role in the dynamics and formation of the fragments. The importance of quantum fluctuations beyond the independent particle/quasi-particle picture is underlined and qualitatively studied.

Scamps, Guillaume; Lacroix, Denis

2015-01-01T23:59:59.000Z

116

Fission-energy release for 16 fissioning nuclides. Final report  

SciTech Connect (OSTI)

Results are presented of a least-squares evaluation of the components of energy release per fission in /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 239/Pu, and /sup 241/Pu. For completeness, older (1978) results based on systematics are presented for these and ten other isotopes of interest. There have been recent indications that the delayed energy components may be somewhat higher than those used previously, but the LSQ results do not seem to change significantly when modest (approx. 1 MeV) increases in the total delayed energy are included in the inputs. Additional measurements of most of the energy components are still needed to resolve remaining discrepancies.

Sher, R.

1981-03-01T23:59:59.000Z

117

Study of dissipative dynamics in fission of hot nuclei using Langevin equation  

E-Print Network [OSTI]

The fission of highly excited compound nuclei formed in heavy ion induced fusion reactions has emerged as a topic of considerable interest in the recent years. Dissipative dynamical models based on the Langevin equation were developed and were applied successfully for fission dynamics of highly excited heavy nuclei. However, Wall Friction(WF), the standard version of nuclear friction when incorporated in the Langevin dynamical model was not able to reproduce simultaneously experimental data for both prescission neutron multiplicity and fission probability. Consequently, an empirical reduction in the strength of the wall friction was found necessary to reproduce the experimental numbers by many workers. Interestingly, a modification of the wall friction was proposed recently where the reduction was achieved microscopically. This modified version is known as the chaos weighted wall friction(CWWF) which takes into account non-integrability of single particle motion. The work in my thesis aims at using this stron...

Chaudhuri, G

2004-01-01T23:59:59.000Z

118

Realistic fission models, new beta-decay half-lives and the r-process in neutron star mergers  

SciTech Connect (OSTI)

Almost half of heavy nuclei beyond iron are considered to be produced by rapid neutron capture process (r-process). This process occurs in the neutron-rich environment such as core-collapse supernovae or neutron star mergers, but the main production site is still unknown. In the r-process of neutron star mergers, nuclear fission reactions play an important role. Also beta-decay half-lives of magic nuclei are crucial for the r-process. We have carried out r-process nucleosynthesis calculations based upon new theoretical estimates of fission fragment distributions and new beta-decay half-lives for N=82 nuclei measured at RIBF-RIKEN. We investigate the effect of nuclear fission on abundance patterns in the matter ejected from neutron star mergers with two different fission fragment mass distributions. We also discuss how the new experimental beta-decay half-lives affect the r-process.

Shibagaki, S.; Kajino, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan and National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Chiba, S. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8850 (Japan); Lorusso, G.; Nishimura, S. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, IN 46556 (United States)

2014-05-02T23:59:59.000Z

119

Study of dissipative dynamics in fission of hot nuclei using Langevin equation  

E-Print Network [OSTI]

The fission of highly excited compound nuclei formed in heavy ion induced fusion reactions has emerged as a topic of considerable interest in the recent years. Dissipative dynamical models based on the Langevin equation were developed and were applied successfully for fission dynamics of highly excited heavy nuclei. However, Wall Friction(WF), the standard version of nuclear friction when incorporated in the Langevin dynamical model was not able to reproduce simultaneously experimental data for both prescission neutron multiplicity and fission probability. Consequently, an empirical reduction in the strength of the wall friction was found necessary to reproduce the experimental numbers by many workers. Interestingly, a modification of the wall friction was proposed recently where the reduction was achieved microscopically. This modified version is known as the chaos weighted wall friction(CWWF) which takes into account non-integrability of single particle motion. The work in my thesis aims at using this strongly shape dependent version of friction (CWWF) in the Langevin dynamical model coupled with particle and gamma evaporation in order to verify to what extent it can account for the experimental data of fission of hot nuclei. The experimental data includes excitation functions of prescission neutron multiplicity, fission probability as well as evaporation residue cross-section of a number of nuclei. The importance of transients in nuclear fission is also discussed. The present endeavour is an effort to obtain a clear physical picture of nuclear dissipation which in turn will help in solving many open problems related to collective motion, and in particular, nuclear fission.

Gargi Chaudhuri

2004-11-01T23:59:59.000Z

120

Nuclear Thermal Rockets: The Physics of the Fission Reactor  

E-Print Network [OSTI]

Nuclear Thermal Rockets: The Physics of the Fission Reactor Shane D. Ross Control and Dynamical heats up when it passes through a nuclear reactor, where controlled fission of some fissionable material, with the nuclear fission reactor as a heat source [Lawrence, Witter, and Humble, 1992]. it works essentially

Ross, Shane

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Future challenges for nuclear data research in fission (u)  

SciTech Connect (OSTI)

I describe some high priority research areas in nuclear fission, where applications in nuclear reactor technologies and in modeling criticality in general are demanding higher accuracies in our databases. We focus on fission cross sections, fission neutron spectra, and fission product data.

Chadwick, Mark B [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

122

Reactor power history from fission product signatures  

E-Print Network [OSTI]

The purpose of this research was to identify fission product signatures that could be used to uniquely identify a specific spent fuel assembly in order to improve international safeguards. This capability would help prevent and deter potential...

Sweeney, David J.

2009-05-15T23:59:59.000Z

123

Nuclear fission as resonance-mediated conductance  

E-Print Network [OSTI]

For 75 years the theory of nuclear fission has been based on the existence of a collective coordinate associated with the nuclear shape, an assumption required by the Bohr-Wheeler formula as well as by the R-matrix theory of fission. We show that it is also possible to formulate the theory without the help of collective coordinates. In the new formulation, fission is facilitated by individual states in the barrier region rather than channels over the barrier. In a certain limit the theory reduces to a formula closely related to the formula for electronic conductance through resonant tunneling states. In contrast, conduction through channels gives rise to a staircase excitation function that is well-known in nanoscale electronics but has never been seen in nuclear fission.

G. F. Bertsch

2014-12-18T23:59:59.000Z

124

FP7 Euratom Work Programme Call title: Nuclear Fission and Radiation Protection  

E-Print Network [OSTI]

Fission-1.1 Fission-2008-1.1.1: Gas generation and transport in support of performance assessment Large) Fission-1.2 Fission-2008-1.2.1: Establishment of a Central Design team (CDT) for a fast- spectrum-scale or large-scale #12;Reactor Systems: Fission-2 Fission-2.1 Fission-2008-2.1.1: Sustainable integration

De Cindio, Fiorella

125

Modeling Fission Product Sorption in Graphite Structures  

SciTech Connect (OSTI)

The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission products on each type of graphite site. The model will include multiple simultaneous adsorbing species, which will allow for competitive adsorption effects between different fission product species and O and OH (for modeling accident conditions).

Szlufarska, Izabela [University of Wisconsin, Madison, WI (United States); Morgan, Dane [University of Wisconsin, Madison, WI (United States); Allen, Todd [University of Wisconsin, Madison, WI (United States)

2013-04-08T23:59:59.000Z

126

Fission reactor experiments for solid breeder blankets  

SciTech Connect (OSTI)

The testing needs for solid breeder blanket development are different from those for liquid breeder blankets. In particular, a reasonable number of moderate volume test sites in a neutron environment are needed. Existing fission reactors are shown to be able to provide this environment with reasonable simulation of many important blanket conditions. Three major additional fission reactor tests are identified beyond those presently underway. These are thermal behavior, advanced in-situ tritium recovery and nuclear submodule experiments.

Gierszewski, P.J.; Abdou, M.A.; Puigh, R.

1986-11-01T23:59:59.000Z

127

Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions  

SciTech Connect (OSTI)

The decay properties of {sup 290}116 and {sup 291}116, and the dependence of their production cross sections on the excitation energies of the compound nucleus, {sup 293}116, have been measured in the {sup 245}Cm({sup 48}Ca,xn){sup 293-x}116 reaction. These isotopes of element 116 are the decay daughters of element 118 isotopes, which are produced via the {sup 249}Cf+{sup 48}Ca reaction. They performed the element 118 experiment at two projectile energies, corresponding to {sup 297}118 compound nucleus excitation energies of E* = 29.2 {+-} 2.5 and 34.4 {+-} 2.3 MeV. During an irradiation with a total beam dose of 4.1 x 10{sup 19} {sup 48}Ca projectiles, three similar decay chains consisting of two or three consecutive {alpha} decays and terminated by a spontaneous fission (SF) with high total kinetic energy of about 230 MeV were observed. The three decay chains originated from the even-even isotope {sup 294}118 (E{sub {alpha}} = 11.65 {+-} 0.06 MeV, T{sub {alpha}} = 0.89{sub -0.31}{sup +1.07} ms) produced in the 3n-evaporation channel of the {sup 249}Cf+{sup 48}Ca reaction with a maximum cross section of 0.5{sub -0.3}{sup +1.6} pb.

Oganessian, Y T; Utyonkov, V K; Lobanov, Y V; Abdullin, F S; Polyakov, A N; Sagaidak, R N; Shirokovsky, I V; Tsyganov, Y S; Voinov, A A; Gulbekian, G G; Bogomolov, S L; Gikal, B N; Mezentsev, A N; Iliev, S; Subbotin, V G; Sukhov, A M; Subotic, K; Zagrebaev, V I; Vostokin, G K; Itkis, M G; Moody, K J; . Patin, J B; Shaughnessy, D A; Stoyer, M A; Stoyer, N J; Wilk, P A; Kenneally, J M; Landrum, J H; Wild, J F; Lougheed, R W

2006-01-31T23:59:59.000Z

128

Theoretical descriptions of neutron emission in fission  

SciTech Connect (OSTI)

Brief descriptions are given of the observables in neutron emission in fission together with early theoretical representations of two of these observables, namely, the prompt fission neutron spectrum N(E) and the average prompt neutron multiplicity {bar {nu}}{sub p}. This is followed by summaries, together with examples, of modern approaches to the calculation of these two quantities. Here, emphasis is placed upon the predictability and accuracy of the new approaches. In particular, the dependencies of N(E) and {bar {nu}}{sub p} upon the fissioning nucleus and its excitation energy are discussed. Then, recent work in multiple-chance fission and other recent work involving new measurements are presented and discussed. Following this, some properties of fission fragments are mentioned that must be better known and better understood in order to calculate N(E) and {bar {nu}}{sub p} with higher accuracy than is currently possible. In conclusion, some measurements are recommended for the purpose of benchmarking simultaneous calculations of neutron emission and gamma emission in fission. 32 refs., 26 figs.

Madland, D.G.

1990-01-01T23:59:59.000Z

129

Statistics at work in heavy-ion reactions  

SciTech Connect (OSTI)

In the first part special aspects of the compound nucleus decay are considered. The evaporation of particles intermediate between nucleons and fission fragments is explored both theoretically and experimentally. The limitations of the fission decay width expression obtained with the transition state method are discussed, and a more general approach is proposed. In the second part the process of angular momentum transfer in deep inelastic reactions is considered. The limit of statistical equilibrium is studied and specifically applied to the estimation of the degree of alignment of the fragment spins. The magnitude and alignment of the transferred angular momentum is experimentally determined from sequentially emitted alpha, gamma, and fission fragments.

Moretto, L.G.

1982-07-01T23:59:59.000Z

130

E-Print Network 3.0 - asymmetric nucleon-induced fission Sample...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

POLONICA B No 4 BIMODAL FISSION Summary: modes allows to describe observed asymmetric fis- sion of 256 Fm, as well as bimodal fission of 258 Fm... fission, respectively....

131

E-Print Network 3.0 - asymmetrical fission type Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

POLONICA B No 4 BIMODAL FISSION Summary: modes allows to describe observed asymmetric fis- sion of 256 Fm, as well as bimodal fission of 258 Fm... fission, respectively....

132

Mass Chain Evaluation for A=95  

SciTech Connect (OSTI)

A full evaluation of the mass chain A = 95 has been done in the ENSDF format taking into account all the available data until June 2009. Excited states populated by in-beam nuclear reactions and by radioactive decay have been considered. The 'evp' editor, developed at the NNDC, has been used for the evaluation. This mass chain was last evaluated in 1993. Many new and improved data were reported since then. A total of 13 nuclei have been evaluated.

Basu, S.K.; Sonzogni, A.; Basu, Swapan Kr.; Mukherjee, Gopal; Sonzogni, A. A.

2011-08-01T23:59:59.000Z

133

Pre-neutron emission mass distributions for low-energy neutron-induced actinide fission  

E-Print Network [OSTI]

According to the driving potential of a fissile system, we propose a phenomenological fission potential for a description of the pre-neutron emission mass distributions of neutron-induced actinide fission. Based on the nucleus-nucleus potential with the Skyrme energy-density functional, the driving potential of the fissile system is studied considering the deformations of nuclei. The energy dependence of the potential parameters is investigated based on the experimental data for the heights of the peak and valley of the mass distributions. The pre-neutron emission mass distributions for reactions 238U(n, f), 237Np(n, f), 235U(n, f), 232Th(n, f) and 239Pu(n, f) can be reasonably well reproduced. Some predictions for these reactions at unmeasured incident energies are also presented.

Xiaojun Sun; Chenggang Yu; Ning Wang

2012-01-15T23:59:59.000Z

134

Interlaboratory reaction rate program. 12th progress report, November 1976-October 1979  

SciTech Connect (OSTI)

The Interlaboratory Reaction Rate UILRR) program is establishing the capability to accurately measure neutron-induced reactions and reaction rates for reactor fuels and materials development programs. The goal for the principal fission reactions, /sup 235/U, /sup 238/U and /sup 239/Pu, is an accuracy to within +- 5% at the 95% confidence level. Accurate measurement of other fission and nonfission reactions is also required, but to a lesser accuracy, between +- 5% and 10% at the 95% confidence level. A secondary program objective is improvement in knowledge of the nuclear parameters involved in the standarization of fuels and materials dosimetry measurements of neutron flux, spectra, fluence and burnup.

Lippincott, E.P.; McElroy, W.N.; Preston, C.C. (comps.)

1980-09-01T23:59:59.000Z

135

True ternary fission, the collinear cluster tripartition (CCT) of {sup 252}Cf  

SciTech Connect (OSTI)

In systematic work over the last decade (see Pyatkov et al. [12] and refs therein), the ternary fission decay of heavy nuclei, in {sup 235}U(n,fff) and {sup 252}Cf(sf) has been studied in a collinear geometry. The name used for this process is (CCT), with three fragments of similar size in a collinear decay, it is the true ternary fission. This decay has been observed in spontaneous fission as well as in a neutron induced reaction. The measurements are based on different experimental set-ups, with binary coincidences containing TOF and energy determinations. With two detector telescopes placed at 180 Degree-Sign , the measurements of masses and energies of each of the registered two fragments, give complete kinematic solutions. Thus the missing mass events in binary coincidences can be determined, these events are obtained by blocking one of the lighter fragments on a structure in front of the detectors. The relatively high yield of CCT (more than 10{sup -3} per binary fission) is explained. It is due to the favourable Q-values (more positive than for binary) and the large phase space of the ternary CCT-decay, dominated by three (magic) clusters: e.g. isotopes of Sn, Ca and Ni, {sup 132}Sn+{sup 50}Ca+{sup 70}Ni. It is shown that the collinear (prolate) geometry has the favoured potential energy relative to the oblate shapes. The ternary fission is considered to be a sequential process. With this assumption the kinetic energies of the fragments have been calculated by Vijay et al.. The third fragments have very low kinetic energies (below 20 MeV) and have thus escaped their detection in previous work on 'ternary fission', where in addition an oblate shape and a triangle for the momentum vectors have been assumed.

Oertzen, W. von; Pyatkov, Y. V.; Kamanin, D. [Helmholtz Zentrum, D14109 Berlin (Germany); Flerov Laboratory of Nuclear Reactions, JINR, Dubna, Moscow region (Russian Federation); Flerov Laboratory of Nuclear Reactions, JINR, Dubna, Moscow region (Russian Federation) and Helmholtz Zentrum, D14109 Berlin (Germany)

2012-10-20T23:59:59.000Z

136

Interference of fission amplitudes of neutron resonances and T-odd asymmetry for various prescission third particles in the ternary fission of nuclei  

SciTech Connect (OSTI)

Differential cross sections for reactions of the true ternary fission of nuclei that was induced by cold polarized neutrons were constructed with allowance of the effect that Coriolis interaction and the interference between fission amplitudes of neutron resonances excited in fissile nuclei upon incidentneutron capture by target nuclei exerted on angular distributions of prescission third particles (alpha particles, neutrons, or photons). It is shown that T -odd TRI- and ROT-type asymmetries for prescission alpha particles are associated with, respectively, the odd and even components of the Coriolis interaction-perturbed amplitude of angular distributions of particles belonging to the types indicated above. These asymmetries have angular distributions differing from each other and stemming from a nontrivial dependence of these components on the neutron-resonance spins J{sub s} and their projections K{sub s} onto the symmetry axis of the nucleus involved. It is shown that angular distributions of prescission photons and neutrons from reactions of the ternary fission of nuclei that is induced by cold polarized neutrons are determined by the effect of Coriolis forces exclusively. Therefore, the emerging T-odd asymmetries have a character of a ROT-type asymmetry and are universal for all target nuclei.

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru [Voronezh State University (Russian Federation); Bunakov, V. E. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation); Kadmensky, S. S. [Voronezh State University (Russian Federation)

2011-12-15T23:59:59.000Z

137

Spectroscopy of element 115 decay chains  

SciTech Connect (OSTI)

A high-resolution a, X-ray and -ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum fu r Schwerionenforschung. Thirty correlated a-decay chains were detected following the fusion-evaporation reaction 48Ca + 243Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z = 115. The data includes first candidates of fingerprinting the decay step Mt --> Bh with characteristic X rays. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z > 112. Comprehensive Monte-Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation.

Rudolph, Dirk [Lund University, Sweden; Forsberg, U. [Lund University, Sweden; Golubev, P. [Lund University, Sweden; Sarmiento, L. G. [Lund University, Sweden; Yakushev, A. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Andersson, L.-L. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Di Nitto, A. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Duehllmann, Ch. E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Gates, J. M. [Lawrence Berkeley National Laboratory (LBNL); Gregorich, K. E. [Lawrence Berkeley National Laboratory (LBNL); Gross, Carl J [ORNL; Hessberger, F. P. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Herzberg, R.-D [University of Liverpool; Khuyagbaatar, J. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Kratz, J. V. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Rykaczewski, Krzysztof Piotr [ORNL; Schaedel, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Aberg, S. [Lund University, Sweden; Ackermann, D. [GSI-Hemholtzzentrum fur Schwerionenforschung, Darmstadt, Germany; Block, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Brand, H. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Carlsson, B. G. [Lund University, Sweden; Cox, D. [University of Liverpool; Derkx, X. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Eberhardt, K. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Even, J. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Fahlander, C. [Lund University, Sweden; Gerl, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Jaeger, E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kindler, B. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Krier, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kojouharov, I. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kurz, N. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Lommel, B. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Mistry, A. [University of Liverpool; Mokry, C. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Nitsche, H. [Lawrence Berkeley National Laboratory (LBNL); Omtvedt, J. P. [Paul Scherrer Institut, Villigen, Switzerland; Papadakis, P. [University of Liverpool; Ragnarsson, I. [Lund University, Sweden; Runke, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Schaffner, H. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Schausten, B. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Thoerle-Pospiech, P. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Torres, T. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Traut, T. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Tuerler, A. [Paul Scherrer Institut, Villigen, Switzerland; Ward, A. [University of Liverpool; Ward, D. E. [Lund University, Sweden; Wiehl, N. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany

2013-01-01T23:59:59.000Z

138

T invariance and T-odd asymmetries for the cold-polarized-neutron-induced fission of nonoriented nuclei  

SciTech Connect (OSTI)

It is shown that the coefficients D{sup exp} for all T-odd asymmetries observed experimentally in the cross sections for the reactions of cold-polarized-neutron-induced fission of nonoriented target nuclei (which involves the emission of prescission and evaporated particles) comply in shape and scale with the coefficients D{sup theor} calculated for the analogous asymmetries on the basis of quantum-mechanical nuclear-fission theory for T-invariant Hamiltonians of fissile systems. It is also shown that the asymmetries in question arise upon taking into account the effect of (i) the interference between the fission amplitudes of s- and p-wave resonances of a polarized fissile compound nucleus formed in the aforementioned reactions; (ii) the collective rotation of the compound nucleus in question (this rotation entails a change in the angular distributions of fission fragments and third particles); and (iii) the wriggling vibrations of this compound nucleus in the vicinity of its scission point, which lead to the appearance of high aligned spins of fission fragments, with the result that the emission of neutrons and photons evaporated from these fragments becomes anisotropic. The possible contribution of T-noninvariant interactions to the formation of the T-odd asymmetries under analysis is estimated by using the results obtained in experimentally testing the detailed-balance principle, (P-A) theorem, and T invariance of cross sections for elastic proton-proton and proton-neutron scattering.

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru [Voronezh State University (Russian Federation); Bunakov, V. E. [National Research Center Kurchatov Institute, Petersburg Nuclear Physics Institute (Russian Federation); Titova, L. V. [Voronezh State University (Russian Federation)

2014-12-15T23:59:59.000Z

139

Statistical Model Analysis of (n,p) Cross Sections and Average Energy For Fission Neutron Spectrum  

SciTech Connect (OSTI)

Investigation of charged particle emission reaction cross sections for fast neutrons is important to both nuclear reactor technology and the understanding of nuclear reaction mechanisms. In particular, the study of (n,p) cross sections is necessary to estimate radiation damage due to hydrogen production, nuclear heating and transmutations in the structural materials of fission and fusion reactors. On the other hand, it is often necessary in practice to evaluate the neutron cross sections of the nuclides for which no experimental data are available.Because of this, we carried out the systematical analysis of known experimental (n,p) and (n,a) cross sections for fast neutrons and observed a systematical regularity in the wide energy interval of 6-20 MeV and for broad mass range of target nuclei. To explain this effect using the compound, pre-equilibrium and direct reaction mechanisms some formulae were deduced. In this paper, in the framework of the statistical model known experimental (n,p) cross sections averaged over the thermal fission neutron spectrum of U-235 are analyzed. It was shown that the experimental data are satisfactorily described by the statistical model. Also, in the case of (n,p) cross sections the effective average neutron energy for fission spectrum of U-235 was found to be around 3 MeV.

Odsuren, M.; Khuukhenkhuu, G. [Nuclear Research Center, National University of Mongolia, Ulaanbaatar (Mongolia)

2011-06-28T23:59:59.000Z

140

Energy partition in low energy fission  

E-Print Network [OSTI]

The intrinsic excitation energy of fission fragments is dynamically evaluated in terms of the time dependent pairing equations. These equations are corroborated with two conditions. One of them fixes the number of particles and the another separates the pairing active spaces associated to the two fragments in the vicinity of the scission configuration. The fission path is obtained in the frame of the macroscopic-microscopic model. The single particle level schemes are obtained within the two center Woods-Saxon shell model. It is shown that the available intrinsic dissipated energy is not shared proportionally to the masses of the two fission fragments. If the heavy fragment possesses nucleon numbers close to the magic ones, the accumulated intrinsic excitation energy is lower than that of the light fragment.

M. Mirea

2011-02-14T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

achieve comparable fission: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

that. H. Abusara; A. V. Afanasjev; P. Ring 2010-10-09 9 Benchmarking Nuclear Fission Theory Nuclear Experiment (arXiv) Summary: We suggest a small set of fission observables...

142

accompanied ternary fission: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

2, it i.e. Aii2. Gennady Volkov 2010-06-29 25 Benchmarking Nuclear Fission Theory Nuclear Experiment (arXiv) Summary: We suggest a small set of fission observables...

143

active inspection fission: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

K. Tittelmeier; D. Vartsky; H. Wershofen 2012-01-04 12 Benchmarking Nuclear Fission Theory Nuclear Experiment (arXiv) Summary: We suggest a small set of fission observables...

144

Italian hybrid and fission reactors scenario analysis  

SciTech Connect (OSTI)

Italy is a country where a long tradition of studies both in the fission and fusion field is consolidated; nevertheless a strong public opinion concerned with the destination of the Spent Nuclear Fuel hinders the development of nuclear power. The possibility to a severe reduction of the NSF mass generated from a fleet of nuclear reactors employing an hypothetical fusionfission hybrid reactor has been investigated in the Italian framework. The possibility to produce nuclear fuel for the fission nuclear reactors with the hybrid reactor was analyzed too.

Ciotti, M.; Manzano, J.; Sepielli, M. [ENEA CR Frascati, Via Enrico Fermi, 45, 00044, Frascati, Roma (Italy); ENEA CR casaccia, Via Anguillarese, 301, 00123, Santa Maria di Galeria, Roma (Italy)

2012-06-19T23:59:59.000Z

145

Half-life for spontaneous fission of /sup 243/Cm  

SciTech Connect (OSTI)

A method is proposed for measuring the half-life for spontaneous fission of curium 243. Isotope separation and purification techniques are described and the isotope ratio of the purified target is given. The efficiency of fission fragment detection for solid state mica detectors was measured with a curium 244 standard. Results for the rate of spontaneous fission are tabulated.

Polynov, V.N.; Druzhinin, A.A.; Korochkin, A.M.; Nikitin, E.A.; Bochkarev, V.A.; Vyachin, V.N.; Lapin, V.G.; Maksimov, M.Yu.

1987-10-01T23:59:59.000Z

146

Synthesis of the isotopes of elements 118 and 116 in the {sup 249}Cf and {sup 245}Cm+{sup 48}Ca fusion reactions  

SciTech Connect (OSTI)

The decay properties of {sup 290}116 and {sup 291}116, and the dependence of their production cross sections on the excitation energies of the compound nucleus, {sup 293}116, have been measured in the {sup 245}Cm ({sup 48}Ca, xn){sup 293-x}116 reaction. These isotopes of element 116 are the decay daughters of element 118 isotopes, which are produced via the {sup 249}Cf+{sup 48}Ca reaction. We performed the element 118 experiment at two projectile energies, corresponding to {sup 297}118 compound nucleus excitation energies of E*=29.2{+-}2.5 and 34.4{+-}2.3 MeV. During an irradiation with a total beam dose of 4.1x10{sup 19} {sup 48}Ca projectiles, three similar decay chains consisting of two or three consecutive {alpha} decays and terminated by a spontaneous fission (SF) with high total kinetic energy of about 230 MeV were observed. The three decay chains originated from the even-even isotope {sup 294}118 (E{sub {alpha}}=11.65{+-}0.06 MeV, T{sub {alpha}}=0.89{sub -0.31}{sup +1.07} ms) produced in the 3n-evaporation channel of the {sup 249}Cf+{sup 48}Ca reaction with a maximum cross section of 0.5{sub -0.3}{sup +1.6} pb.

Oganessian, Yu. Ts.; Utyonkov, V. K.; Lobanov, Yu. V.; Abdullin, F. Sh.; Polyakov, A. N.; Sagaidak, R. N.; Shirokovsky, I. V.; Tsyganov, Yu. S.; Voinov, A. A.; Gulbekian, G. G.; Bogomolov, S. L.; Gikal, B. N.; Mezentsev, A. N.; Iliev, S.; Subbotin, V. G.; Sukhov, A. M.; Subotic, K.; Zagrebaev, V. I.; Vostokin, G. K.; Itkis, M. G. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); University of California, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] (and others)

2006-10-15T23:59:59.000Z

147

Fission barriers and probabilities of spontaneous fission for elements with Z$\\geq$100  

E-Print Network [OSTI]

This is a short review of methods and results of calculations of fission barriers and fission half-lives of even-even superheavy nuclei. An approvable agreement of the following approaches is shown and discussed: The macroscopic-microscopic approach based on the stratagem of the shell correction to the liquid drop model and a vantage point of microscopic energy density functionals of Skyrme and Gogny type selfconsistently calculated within Hartree-Fock-Bogoliubov method. Mass parameters are calculated in the Hartree-Fock-Bogoliubov cranking approximation. A short part of the paper is devoted to the nuclear fission dynamics. We also discuss the predictive power of Skyrme functionals applied to key properties of the fission path of $^{266}$Hs. It applies the standard techniques of error estimates in the framework of a $\\chi^2$ analysis.

Baran, A; Reinhard, P -G; Robledo, L M; Staszczak, A; Warda, M

2015-01-01T23:59:59.000Z

148

E-Print Network 3.0 - allele-specific polymerase chain Sample...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

is allele-specific Polymerase Chain Reaction (PCR). This requires genomic DNA Source: Los Alamos National Laboratory, Theoretical Division, Condensed Matter and Statistical Physics...

149

Density Functional Theory Approach to Nuclear Fission  

E-Print Network [OSTI]

The Skyrme nuclear energy density functional theory (DFT) is used to model neutron-induced fission in actinides. This paper focuses on the numerical implementation of the theory. In particular, it reports recent advances in DFT code development on leadership class computers, and presents a detailed analysis of the numerical accuracy of DFT solvers for near-scission calculations.

N. Schunck

2013-01-20T23:59:59.000Z

150

FISSION REACTORS KEYWORDS: core-barrel vibra-  

E-Print Network [OSTI]

FISSION REACTORS KEYWORDS: core-barrel vibra- tions, in-core neutron noise, shell- mode vibrations CALCULATION OF THE NEUTRON NOISE INDUCED BY SHELL-MODE CORE-BARREL VIBRATIONS IN A 1-D, TWO-GROUP, TWO-REGION SLAB REACTOR MODEL CARL SUNDE,* CHRISTOPHE DEMAZI�RE, and IMRE PÁZSIT Chalmers University of Technology

Demazière, Christophe

151

Fission Fragment Distributions and Delayed Neutron Yields from Photon-Induced-Fission  

SciTech Connect (OSTI)

Fission fragment distributions and delayed neutron yields for 235U and 238U are provided by a complete modelization of the photofission process below 25 MeV. The absorption cross-section parameterization and the fission fragment distributions are given and compared to experimental data. The delayed neutron yields and the half-lives in terms of six groups are presented and compared to data obtained with a bremsstrahlung spectrum of 15 MeV.

David, J.-C.; Dore, D.; Giacri-Mauborgne, M.-L.; Ridikas, D.; Lauwe, A. van [DSM/DAPNIA/SPhN, CEA/Saclay, F-91191 Gif-sur-Yvette cedex (France)

2005-05-24T23:59:59.000Z

152

Fission Yield Measurements by Inductively Coupled Plasma Mass-Spectrometry  

SciTech Connect (OSTI)

Correct prediction of the fission products inventory in irradiated nuclear fuels is essential for accurate estimation of fuel burnup, establishing proper requirements for spent fuel transportation and storage, materials accountability and nuclear forensics. Such prediction is impossible without accurate knowledge of neutron induced fission yields. Unfortunately, the accuracy of the fission yields reported in the ENDF/B-VII.0 library is not uniform across all of the data and much of the improvement is desired for certain isotopes and fission products. We discuss our measurements of cumulative fission yields in nuclear fuels irradiated in thermal and fast reactor spectra using Inductively Coupled Plasma Mass Spectrometry.

Irina Glagolenko; Bruce Hilton; Jeffrey Giglio; Daniel Cummings; Karl Grimm; Richard McKnight

2009-11-01T23:59:59.000Z

153

Low-Energy Fusion-Fission Dynamics of Heavy Nuclear Systems  

SciTech Connect (OSTI)

A new approach is proposed for a unified description of strongly coupled deep-inelastic (DI) scattering, fusion, fission, and quasi-fission (QF) processes of heavy ion collisions. A unified driving-potential and a unified set of dynamic Langevin-type equations of motion are used in this approach. This makes it possible to perform a full (continuous) time analysis of the evolution of heavy nuclear systems, starting from the approaching stage, moving up to the formation of the compound nucleus or emerging into two final fragments. The calculated mass, charge, energy and angular distributions of the reaction products agree well with the corresponding experimental data for heavy and superheavy nuclear systems. Collisions of very heavy nuclei (such as 238U+248Cm) are investigated as an alternative way for production of superheavy elements. Large charge and mass transfer was found in these reactions due to the inverse (anti-symmetrizing) quasi-fission process leading to formation of surviving superheavy long-lived neutron-rich nuclei.

Zagrebaev, Valery [Flerov Laboratory of Nuclear Reaction, JINR, Dubna, 141980, Moscow region (Russian Federation); Greiner, Walter [Frankfurt Institute for Advanced Studies, J.W. Goethe-Universitaet, Frankfurt (Germany)

2006-08-14T23:59:59.000Z

154

Studies of the /sup 32/S + /sup 182/W reaction  

SciTech Connect (OSTI)

Fission-like products from the reaction /sup 32/S + /sup 182/W were measured over the entire angular range from theta = 10-170/sup 0/ and for bombarding energies of E/sub lab/ = 166, 177, 222, and 260 MeV using an array of eight Si detectors. From the measured energy and flight time the product mass was determined event-by-event by performing the appropriate corrections for the plasma delay and pulse height defect associated with Si detectors. The mass, angular, and total kinetic energy distributions of fission-like fragments are obtained by assuming two-body kinematics. The angular distributions indicate that a fraction of the observed cross section is associated with quasi-fission reactions as observed previously in several other reactions involving /sup 32/S projectiles. Furthermore, we observe an angular dependence of the fragment mass distributions, a feature which is strictly incompatible with compound nucleus decay. Both of these observations indicate that a fraction of fission-like products originate from quasi-fission, a process in which a large degree of mass transfer occurs between the two interaction nuclei in a short time scale. 14 refs., 4 figs., 1 tab.

Back, B.B.; Keller, J.G.; Worsham, A.; Glagola, B.G.; Henderson, D.; Kaufman, S.; Sanders, S.J.; Siemssen, R.; Videbaek, F.; Wilkins, B.D.

1986-01-01T23:59:59.000Z

155

Fusion-fission energy systems evaluation  

SciTech Connect (OSTI)

This report serves as the basis for comparing the fusion-fission (hybrid) energy system concept with other advanced technology fissile fuel breeding concepts evaluated in the Nonproliferation Alternative Systems Assessment Program (NASAP). As such, much of the information and data provided herein is in a form that meets the NASAP data requirements. Since the hybrid concept has not been studied as extensively as many of the other fission concepts being examined in NASAP, the provided data and information are sparse relative to these more developed concepts. Nevertheless, this report is intended to provide a perspective on hybrids and to summarize the findings of the rather limited analyses made to date on this concept.

Teofilo, V.L.; Aase, D.T.; Bickford, W.E.

1980-01-01T23:59:59.000Z

156

Delayed-fission properties of neutron-deficient americium nuclei  

SciTech Connect (OSTI)

Characteristics of the delayed-fission decay mode in light americium nuclei have been investigated. Measurements on the unknown isotopes {sup 230}Am and {sup 236}Am were attempted, and upper limits on the delayed-fission branches of these nuclei were determined. Evidence of the existence of {sup 236}Am was observed in radiochemical separations. Total kinetic energy and mass-yield distributions of the electron-capture delayed-fission mode were measured for {sup 232}Am (t{sub 1/2} = 1.31 {plus minus} 0.04 min) and for {sup 234}Am (t{sub 1/2} = 2.32 {plus minus} 0.08 min), and delayed-fission probabilities of 6.9 {times} 10{sup {minus}4} and 6.6 {times} 10{sup {minus}5}, respectively, were determined. The total kinetic energy and the asymmetric mass-yield distributions are typical of fission of mid-range actinides. No discernible influence of the anomalous triple-peaked mass division characteristic of the thorium-radium region was detected. Measurements of the time correlation between the electron-capture x-rays and the subsequent fission conform that the observed fissions arise from the electron-capture delayed-fission mechanism. Delayed fission has provided a unique opportunity to extend the range of low-energy fission studies to previously inaccessible regions. 71 refs., 44 figs., 13 tabs.

Hall, H.L. (California Univ., Berkeley, CA (USA). Dept. of Chemistry)

1989-10-23T23:59:59.000Z

157

Fission-product-decay characteristics. Master's thesis  

SciTech Connect (OSTI)

This theses determined fission-product decay characteristics , including the total activity, the gamma-ray emission rate (GER) and gamma-ray energy spectra. The activity and GER decay were compared to Way and Wigner's t(exp(-1.2)) approximation, and the effects the spectra, activity, and GER have on the Source Normalization Constant (K) were examined. Most of the fission-product data were obtained from DKPOWR, and were compared with data obtained from ORIGIN2. Since the gamma rays are of primary concern in fallout studies, the GER is used instead of activity. The ratio of GER to activity changes significantly with time. Results of this study calculate a GER of 590 x 10/sup 16/ gamma rays/second per kT of fission yield from U-235 fuel and a K of 7059 R/Hr/(kT/sq.km.). The calculation of K includes the contribution from scattered photons. The GER result is 11% higher than reference values, while the K is within 2% of the current value in Glasstone and Dolan's The Effects of Nuclear Weapons. The Ks for Pu-239 and U-238 were within 5% of the U-235 results. The wax-wigners t(exp(-1.2)) approximation differs from time dependent GER and K up to 85% for times less than 6 months. The approximation is not valid for the GER or K at times greater than 6 months. The approximation is within about 45%, for the activity from fission-product decay to at least 5 years. A more accurate measure of exposure requires a numerical integration of the time dependent GER and Source Normalization Constant.

Millage, K.K.

1989-03-01T23:59:59.000Z

158

Time dependent particle emission from fission products  

SciTech Connect (OSTI)

Decay heating following nuclear fission is an important factor in the design of nuclear facilities; impacting a variety of aspects ranging from cooling requirements to shielding design. Calculations of decay heat, often assumed to be a simple product of activity and average decay product energy, are complicated by the so called 'pandemonium effect'. Elucidated in the 1970's this complication arises from beta-decays feeding high-energy nuclear levels; redistributing the available energy between betas and gammas. Increased interest in improving the theoretical predictions of decay probabilities has been, in part, motivated by the recent experimental effort utilizing the Total Absorption Gamma-ray Spectrometer (TAGS) to determine individual beta-decay transition probabilities to individual nuclear levels. Accurate predictions of decay heating require a detailed understanding of these transition probabilities, accurate representation of particle decays as well as reliable predictions of temporal inventories from fissioning systems. We will discuss a recent LANL effort to provide a time dependent study of particle emission from fission products through a combination of Quasiparticle Random Phase Approximation (QRPA) predictions of beta-decay probabilities, statistical Hauser-Feshbach techniques to obtain particle and gamma-ray emissions in statistical Hauser-Feshbach and the nuclear inventory code, CINDER.

Holloway, Shannon T [Los Alamos National Laboratory; Kawano, Toshihiko [Los Alamos National Laboratory; Moller, Peter [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

159

Polypeptide chain collapse and protein folding Jayant B. Udgaonkar  

E-Print Network [OSTI]

Review Polypeptide chain collapse and protein folding Jayant B. Udgaonkar National Centre is an integral component of a protein folding reaction. In this review, exper- imental characterization solvent [2]. A distinctive physical feature of any protein folding reaction is the greater than 3-fold

160

A fission-fusion hybrid reactor in steady-state L-mode tokamak configuration with natural uranium  

SciTech Connect (OSTI)

This work develops a conceptual design for a fusion-fission hybrid reactor operating in steady-state L-mode tokamak configuration with a subcritical natural or depleted uranium pebble bed blanket. A liquid lithium-lead alloy breeds enough tritium to replenish that consumed by the D-T fusion reaction. The fission blanket augments the fusion power such that the fusion core itself need not have a high power gain, thus allowing for fully non-inductive (steady-state) low confinement mode (L-mode) operation at relatively small physical dimensions. A neutron transport Monte Carlo code models the natural uranium fission blanket. Maximizing the fission power gain while breeding sufficient tritium allows for the selection of an optimal set of blanket parameters, which yields a maximum prudent fission power gain of approximately 7. A 0-D tokamak model suffices to analyze approximate tokamak operating conditions. This fission blanket would allow the fusion component of a hybrid reactor with the same dimensions as ITER to operate in steady-state L-mode very comfortably with a fusion power gain of 6.7 and a thermal fusion power of 2.1 GW. Taking this further can determine the approximate minimum scale for a steady-state L-mode tokamak hybrid reactor, which is a major radius of 5.2 m and an aspect ratio of 2.8. This minimum scale device operates barely within the steady-state L-mode realm with a thermal fusion power of 1.7 GW. Basic thermal hydraulic analysis demonstrates that pressurized helium could cool the pebble bed fission blanket with a flow rate below 10 m/s. The Brayton cycle thermal efficiency is 41%. This reactor, dubbed the Steady-state L-mode non-Enriched Uranium Tokamak Hybrid (SLEUTH), with its very fast neutron spectrum, could be superior to pure fission reactors in terms of breeding fissile fuel and transmuting deleterious fission products. It would likely function best as a prolific plutonium breeder, and the plutonium it produces could actually be more proliferation-resistant than that bred by conventional fast reactors. Furthermore, it can maintain constant total hybrid power output as burnup proceeds by varying the neutron source strength.

Reed, Mark; Parker, Ronald R.; Forget, Benoit [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

2012-06-19T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Exotic fission properties of highly neutron-rich Uranium isotopes  

E-Print Network [OSTI]

The series of Uranium isotopes with $N=154 \\sim 172$ around the magic number N=162/164 are identified to be thermally fissile. The thermal neutron fission of a typical representative $^{249}$U of this region amenable to synthesis in the radioactive ion beam facilities is considered here. Semiempirical study of fission barrier height and width shows this nucleus to be infinitely stable against spontaneous fission due to increase in barrier width arising out of excess neutrons. Calculation of probability of fragment mass yields and microscopic study in relativistic mean field theory, show this nucleus to undergo a new mode of thermal fission decay termed {\\it multifragmentation fission} where a number of prompt scission neutrons are simultaneously released along with the two heavy fission fragments.

L. Satpathy; S. K. Patra; R. K. Choudhury

2007-03-05T23:59:59.000Z

162

Microfabricated sleeve devices for chemical reactions  

DOE Patents [OSTI]

A silicon-based sleeve type chemical reaction chamber that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The reaction chamber combines a critical ratio of silicon and non-silicon based materials to provide the thermal properties desired. For example, the chamber may combine a critical ratio of silicon and silicon nitride to the volume of material to be heated (e.g., a liquid) in order to provide uniform heating, yet low power requirements. The reaction chamber will also allow the introduction of a secondary tube (e.g., plastic) into the reaction sleeve that contains the reaction mixture thereby alleviating any potential materials incompatibility issues. The reaction chamber may be utilized in any chemical reaction system for synthesis or processing of organic, inorganic, or biochemical reactions, such as the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction, which are examples of a synthetic, thermal-cycling-based reaction. The reaction chamber may also be used in synthesis instruments, particularly those for DNA amplification and synthesis.

Northrup, M. Allen (Berkeley, CA)

2003-01-01T23:59:59.000Z

163

Fission product yields for fast-neutron fission of /sup 243,244,246,248/Cm  

SciTech Connect (OSTI)

Recent measurements of relative yields for /sup 95/Zr, /sup 125/Sb, /sup 137/Cs, /sup 141/Ce, /sup 144/Ce, and /sup 155/Eu for fast-neutron fission of samples enriched in the actinides /sup 243,244,246,248/Cm have been combined with a simple mass-distribution model to predict complete mass distributions for fast-neutron fission of each of these four curium actinides. Complete descriptions of the data analysis and of the model and its application and limitations are given.

Dickens, J.K.

1987-05-01T23:59:59.000Z

164

Proton induced fission of 181-Ta at relativistic energies  

E-Print Network [OSTI]

Total fission cross sections of 181-Ta induced by protons at different relativistic energies have been measured at GSI, Darmstadt. The inverse kinematics technique used together with a dedicated set-up, made it possible to determine these cross sections with high accuracy. The new data obtained in this experiment will contribute to the understanding of the fission process at high excitation energies. The results are compared with data from previous experiments and systematics for proton-induced fission cross sections.

Y. Ayyad; J. Benlliure; E. Casarejos; H. Álvarez-Pol; A. Bacquias; A. Boudard; M. Caamaño; T. Enqvist; V. Föhr; A. Keli?-Heil; K. Kezzar; S. Leray; C. Paradela; D. Pérez-Loureiro; R. Pleska?; D. Tarrío

2012-03-07T23:59:59.000Z

165

Ernst Boris Chain CHAIN-FLOREY  

E-Print Network [OSTI]

Professor Benjamin Chain Professor Sir Andrew McMichael Professor Dame Kay Davies 11 Mentors Professor Irene Jiexin Zhao Dr James Tomlinson Dr Thomas Oates Dr Philip Webster Dr Eleanor Sandhu Dr Andrew Innes Dr knowledge of norman heatley, resulted in the isolation and first medical application of an antibiotic

Rosso, Lula

166

Spontaneous fission half-lives for ground state nuclides  

SciTech Connect (OSTI)

Measurements of the spontaneous fission half-lives of nuclides of elements Z = 90 to 108 have been compiled and evaluated. Recommended values are presented.

Holden, N.E. [Brookhaven National Lab., Upton, NY (United States); Hoffman, D.C. [Lawrence Berkeley Lab., CA (United States)

1993-08-01T23:59:59.000Z

167

SciTech Connect: The Microscopic Theory of Fission  

Office of Scientific and Technical Information (OSTI)

CA Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; FISSION; KINETICS; NEUTRONS; SPECTROSCOPY...

168

September 2013 Most Viewed Documents for Fission And Nuclear...  

Office of Scientific and Technical Information (OSTI)

September 2013 Most Viewed Documents for Fission And Nuclear Technologies Science Subject Feed Estimation of gas leak rates through very small orifices and channels. From sealed...

169

January 2013 Most Viewed Documents for Fission And Nuclear Technologie...  

Office of Scientific and Technical Information (OSTI)

January 2013 Most Viewed Documents for Fission And Nuclear Technologies Laboratory studies of shearleach processing of zircaloy clad metallic uranium reactor fuel Swanson, J.L.;...

170

Fission track evidence for widespread early to Middle miocene...  

Open Energy Info (EERE)

and Range province Jump to: navigation, search OpenEI Reference LibraryAdd to library Conference Proceedings: Fission track evidence for widespread early to Middle miocene...

171

Uncertainties analysis of fission fraction for reactor antineutrino experiments  

E-Print Network [OSTI]

Reactor antineutrino experiment are used to study neutrino oscillation, search for signatures of nonstandard neutrino interaction, and monitor reactor operation for safeguard application. Reactor simulation is an important source of uncertainties for a reactor neutrino experiment. Commercial code is used for reactor simulation to evaluate fission fraction in Daya Bay neutrino experiment, but the source code doesn't open to our researcher results from commercial secret. In this study, The open source code DRAGON was improved to calculate the fission rates of the four most important isotopes in fissions, $^{235}$U,$^{238}$U,$^{239}$Pu and $^{241}$Pu, and then was validated for PWRs using the Takahama-3 benchmark. The fission fraction results are consistent with those of MIT's results. Then, fission fraction of Daya Bay reactor core was calculated by using improved DRAGON code, and the fission fraction calculated by DRAGON agreed well with these calculated by SCIENCE. The average deviation less than 5\\% for all the four isotopes. The correlation coefficient matrix between $^{235}$U,$^{238}$U,$^{239}$Pu and $^{241}$Pu were also studied using DRAGON, and then the uncertainty of the antineutrino flux by the fission fraction was calculated by using the correlation coefficient matrix. The uncertainty of the antineutrino flux by the fission fraction simulation is 0.6\\% per core for Daya Bay antineutrino experiment. The uncertainties source of fission fraction calculation need further to be studied in the future.

X. B. Ma; F. Lu; L. Z. Wang; Y. X. Chen; W. L. Zhong; F. P. An

2015-03-17T23:59:59.000Z

172

Exciton Dynamics and Structural Investigations of Singlet Fission...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Exciton Dynamics and Structural Investigations of Singlet Fission in Molecular Solids October 11, 2012 at 3pm36-428 Michael R. Wasielewski Director, Argonne-Northwestern Solar...

173

Direct reactions for nuclear structure and nuclear astrophysics  

SciTech Connect (OSTI)

Direct reactions are powerful probes for studying the atomic nucleus. Modern direct reaction studies are illuminating both the fundamental nature of the nucleus and its role in nucleosynthetic processes occurring in the cosmos. This report covers experiments using knockout reactions on neutron-deficient fragmentation beams, transfer reactions on fission fragment beams, and theoretical sensitivity studies relating to the astrophysical r-process. Results from experiments on 108,106Sn at the NSCL, and on 131Sn at HRIBF are presented as well as the results from the nucleosynthesis study.

Jones, Katherine Louise [University of Tennessee

2014-12-18T23:59:59.000Z

174

Dynamical fission in {sup 124}Sn+{sup 64}Ni collision at 35A MeV  

SciTech Connect (OSTI)

Some properties of fast, nonequilibrium splitting of projectiles in the {sup 124}Sn+{sup 64}Ni reaction at 35A MeV were determined using the 4{pi} CHIMERA detector system. In particular the charge distributions, in- and out-of-plane angular distributions, and relative velocities of projectilelike fragments were measured. The time scale of the process was estimated and it turned out that the process is sequential but much faster than the ordinary, equilibrated fission.

De Filippo, E.; Pagano, A.; Cardella, G.; Lanzano, G.; Papa, M.; Pirrone, S.; Politi, G. [INFN, Sezione di Catania and Dipartimento di Fisica e Astronomia, Universita di Catania (Italy); Piasecki, E.; Siwek-Wilczynska, K.; Skwira, I.; Swiderski, L. [Institute of Experimental Physics, Warsaw University, Warsaw (Poland); Amorini, F.; Anzalone, A.; Baran, V.; Bonasera, A.; Cavallaro, S.; Colonna, M.; Di Toro, M.; Giustolisi, F.; Iacono-Manno, M. [INFN, Laboratori Nazionali del Sud and Dipartimento di Fisica e Astronomia, Universita di Catania (Italy)] [and others

2005-06-01T23:59:59.000Z

175

Spontaneous fission modes and lifetimes of super-heavy elements in the nuclear density functional theory  

E-Print Network [OSTI]

Lifetimes of super-heavy (SH) nuclei are primarily governed by alpha decay and spontaneous fission (SF). Here we study the competing decay modes of even-even SH isotopes with 108 density functional theory framework capable of describing the competition between nuclear attraction and electrostatic repulsion. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov approach. Along the path to fission, our calculations allow for the simultaneous breaking of axial and space inversion symmetries; this may result in lowering SF lifetimes by more than seven orders of magnitude in some cases. We predict two competing SF modes: reflection-symmetric and reflection-asymmetric.The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by $^{280}$Hs, $^{284}$Fl, and $^{284}_{118}$Uuo that separates the regions of SH nuclei synthesized in "cold fusion" and "hot fusion" reactions. The region of long-lived SH nuclei is expected to be centered on $^{294}$Ds with a total half-life of ?1.5 days.

A. Staszczak; A. Baran; W. Nazarewicz

2012-08-06T23:59:59.000Z

176

Predicting the production of neutron rich heavy nuclei in multi-nucleon transfer reactions using GRAZING-F  

E-Print Network [OSTI]

Background: Multi-nucleon transfer reactions have recently attracted attention as a possible path to the synthesis of new neutron-rich heavy nuclei. Purpose: We study transfer reactions involving massive nuclei with the intention of understanding if the semi-classical model GRAZING coupled to an evaporation and fission competition model can satisfactory reproduce experimental data on transfer reactions in which fission plays a role. Methods: We have taken the computer code GRAZING and have added fission competition to it (GRAZING-F) using our current understanding of $\\Gamma_n/\\Gamma_f$, fission barriers and level densities. Results: The code GRAZING-F seems to satisfactory reproduce experimental data for $+1p$, $+2p$ and $+3p$ transfers, but has limitations in reproducing measurements of larger above-target and below-target transfers. Nonetheless, we use GRAZING-F to estimate production rates of neutron-rich $N=126$ nuclei, actinides and transactinides. Conclusions: The GRAZING code, with appropriate modific...

Yanez, R

2015-01-01T23:59:59.000Z

177

Calculation of. beta. -delayed fission of sup 180 Tl and application of the quasiparticle random-phase approximation to the prediction of. beta. sup + -decay half-lives of neutron-deficient isotopes  

SciTech Connect (OSTI)

Motivated by a recent measurement of {beta}-delayed fission in the {sup 180}Tl{r arrow}{sup 180}Hg chain, we have calculated the {beta} strength distribution {ital S}{sub {beta}} of the neutron-deficient nuclide {sup 180}Tl within the framework of the proton-neutron quasiparticle random phase approximation ({ital pn}-QRPA). The fission barrier height is then deduced from the measured {beta}-delayed fission probability {ital P}{sub {beta}DF}. In addition, as a test for the reliability of the theoretical strength distributions, {beta}{sup +}/EC half-lives of some isotopic chains are calculated using the {ital pn}-QRPA including both particle-hole and particle-particle Gamow-Teller residual interactions.

Staudt, A.; Hirsch, M.; Muto, K.; Klapdor-Kleingrothaus, H.V. (Max-Planck-Institut fuer Kernphysik, D-6900 Heidelberg (Federal Republic of Germany))

1990-09-24T23:59:59.000Z

178

Feasibility study of a fission-suppressed tokamak fusion breeder  

SciTech Connect (OSTI)

The preliminary conceptual design of a tokamak fissile fuel producer is described. The blanket technology is based on the fission suppressed breeding concept where neutron multiplication occurs in a bed of 2 cm diameter beryllium pebbles which are cooled by helium at 50 atmospheres pressure. Uranium-233 is bred in thorium metal fuel elements which are in the form of snap rings attached to each beryllium pebble. Tritium is bred in lithium bearing material contained in tubes immersed in the pebble bed and is recovered by a purge flow of helium. The neutron wall load is 3 MW/m/sup 2/ and the blanket material is ferritic steel. The net fissile breeding ratio is 0.54 +- 30% per fusion reaction. This results in the production of 4900 kg of /sup 233/U per year from 3000 MW of fusion power. This quantity of fuel will provide makeup fuel for about 12 LWRs of equal thermal power or about 18 1 GW/sub e/ LWRs. The calculated cost of the produced uranium-233 is between $23/g and $53/g or equivalent to $10/kg to $90/kg of U/sub 3/O/sub 8/ depending on government financing or utility financing assumptions. Additional topics discussed in the report include the tokamak operating mode (both steady state and long pulse considered), the design and breeding implications of using a poloidal divertor for impurity control, reactor safety, the choice of a tritium breeder, and fuel management.

Moir, R.W.; Lee, J.D.; Neef, W.S.; Berwald, D.H.; Garner, J.K.; Whitley, R.H.; Ghoniem, N.; Wong, C.P.C.; Maya, I.; Schultz, K.R.

1984-12-01T23:59:59.000Z

179

Fission energy program of the US Department of Energy, FY 1981  

SciTech Connect (OSTI)

Information is presented concerning the National Energy Plan and fission energy policy; fission energy program management; converter reactor systems; breeder reactor systems; and special nuclear evaluations and systems.

Not Available

1980-03-01T23:59:59.000Z

180

Electroplating method for producing ultralow-mass fissionable deposits  

DOE Patents [OSTI]

A method for producing ultralow-mass fissionable deposits for nuclear reactor dosimetry is described, including the steps of holding a radioactive parent until the radioactive parent reaches secular equilibrium with a daughter isotope, chemically separating the daughter from the parent, electroplating the daughter on a suitable substrate, and holding the electroplated daughter until the daughter decays to the fissionable deposit.

Ruddy, Francis H. (Monroeville, PA)

1989-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Chemical factors affecting fission product transport in severe LMFBR accidents  

SciTech Connect (OSTI)

This study was performed as a part of a larger evaluation effort on LMFBR accident, source-term estimation. Purpose was to provide basic chemical information regarding fission product, sodium coolant, and structural material interactions required to perform estimation of fission product transport under LMFBR accident conditions. Emphasis was placed on conditions within the reactor vessel; containment vessel conditions are discussed only briefly.

Wichner, R.P.; Jolley, R.L.; Gat, U.; Rodgers, B.R.

1984-10-01T23:59:59.000Z

182

Ceramic Hosts for Fission Products Immobilization  

SciTech Connect (OSTI)

Natural spinel, perovskite and zirconolite rank among the most leach resistant of mineral forms. They also have a strong affinity for a large number of other elements and including actinides. Specimens of natural perovskite and zirconolite were radioisotope dated and found to have survived at least 2 billion years of natural process while still remain their loading of uranium and thorium . Developers of the Synroc waste form recognized and exploited the capability of these minerals to securely immobilize TRU elements in high-level waste . However, the Synroc process requires a relatively uniform input and hot pressing equipment to produce the waste form. It is desirable to develop alternative approaches to fabricate these durable waste forms to immobilize the radioactive elements. One approach is using a high temperature process to synthesize these mineral host phases to incorporate the fission products in their crystalline structures. These mineral assemblages with immobilized fission products are then isolated in a durable high temperature glass for periods measured on a geologic time scale. This is a long term research concept and will begin with the laboratory synthesis of the pure spinel (MgAl2O4), perovskite (CaTiO3) and zirconolite (CaZrTi2O7) from their constituent oxides. High temperature furnace and/or thermal plasma will be used for the synthesis of these ceramic host phases. Nonradioactive strontium oxide will be doped into these ceramic phases to investigate the development of substitutional phases such as Mg1-xSrxAl2O4, Ca1-xSrxTiO3 and Ca1-xSrxZrTi2O7. X-ray diffraction will be used to establish the crystalline structures of the pure ceramic hosts and the substitution phases. Scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX) will be performed for product morphology and fission product surrogates distribution in the crystalline hosts. The range of strontium doping is planned to reach the full substitution of the divalent metal ions, Mg and Ca, in the ceramic host phases. The immobilization of rear earth (lanthanide series) fission products in these ceramic host phases will also be studied this year. Cerium oxide is chosen to represent the rear earth fission product for substitution studies in spinel, perovskite and zirconolite ceramic hosts. Cerium has +3 and +4 oxidation states and it can replace some of the trivalent or tetravalent host ions to produce the substitution ceramics such as MgAl2-xCexO4, CaTi1-xCexO3, CaZr1-xCexTi2O7 and CaZrTi2-xCexO7. X-ray diffraction analysis will be used to compare the crystalline structures of the pure ceramic hosts and the substitution phases. SEM-EDX analysis will be used to study the Ce distribution in the ceramic host phases. The range of cerium doping is planned to reach the full substitution of the trivalent or tetravalent ions, Al, Ti and Zr, in the ceramic host phases.

Peter C Kong

2010-07-01T23:59:59.000Z

183

European supply chain study  

E-Print Network [OSTI]

Introduction: Supply chain management has been defined as, "..a set of approaches utilized to efficiently integrate suppliers, manufacturers, warehouses and stores, so that merchandise is produced and distributed at the ...

Puri, Mohitkumar

2009-01-01T23:59:59.000Z

184

Improving supply chain resilience  

E-Print Network [OSTI]

Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...

Leung, Elsa Hiu Man

2009-01-01T23:59:59.000Z

185

Fission matrix capability for MCNP, Part II - Applications  

SciTech Connect (OSTI)

This paper describes the initial experience and results from implementing a fission matrix capability into the MCNP Monte Carlo code. The fission matrix is obtained at essentially no cost during the normal simulation for criticality calculations. It can be used to provide estimates of the fundamental mode power distribution, the reactor dominance ratio, the eigenvalue spectrum, and higher mode spatial eigenfunctions. It can also be used to accelerate the convergence of the power method iterations. Past difficulties and limitations of the fission matrix approach are overcome with a new sparse representation of the matrix, permitting much larger and more accurate fission matrix representations. Numerous examples are presented. A companion paper (Part I - Theory) describes the theoretical basis for the fission matrix method. (authors)

Carney, S. E. [University of Michigan, NERS Department, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Brown, F. B. [Los Alamos National Laboratory, Monte Carlo Codes Group, MS A143, PO Box 1663, Los Alamos, NM 87545 (United States); Kiedrowski, B. C. [University of Michigan, NERS Department, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Martin, W. R. [Los Alamos National Laboratory, Monte Carlo Codes Group, MS A143, PO Box 1663, Los Alamos, NM 87545 (United States)

2013-07-01T23:59:59.000Z

186

Multiple-Coincidence Active Neutron Interrogation of Fissionable Materials  

SciTech Connect (OSTI)

Using a beam of tagged 14.1 MeV neutrons to probe for the presence of fissionable materials, we have measured n-?-? coincidences from depleted uranium (DU). The multiple coincidence rate is substantially above that measured from lead, tungsten, and iron. The presence of coincidences involving delayed gammas in the DU time spectra provides a signature for fissionable materials that is distinct from non-fissionable ones. In addition, the information from the tagged neutron involved in the coincidence gives the position of the fissionable material in all three dimensions. The result is an imaging probe for fissionable materials that is more compact and that produces much less radiation than other solutions.

J.P. Hurley, R.P. Keegan, J.R. Tinsley, R. Trainham, and S.C. Wilde

2008-08-06T23:59:59.000Z

187

Improved Fission Neutron Data Base for Active Interrogation of Actinides  

SciTech Connect (OSTI)

This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

2013-11-06T23:59:59.000Z

188

Electron-capture delayed fission properties of neutron-deficient einsteinium nuclei  

SciTech Connect (OSTI)

Electron-capture delayed fission (ECDF) properties of neutron-deficient einsteinium isotopes were investigated using a combination of chemical separations and on-line radiation detection methods. {sup 242}Es was produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at a beam energy of 87 MeV (on target) in the lab system, and was found to decay with a half-life of 11 {+-} 3 seconds. The ECDF of {sup 242}Es showed a highly asymmetric mass distribution with an average pre-neutron emission total kinetic energy (TKE) of 183 {+-} 18 MeV. The probability of delayed fission (P{sub DF}) was measured to be 0.006 {+-} 0.002. In conjunction with this experiment, the excitation functions of the {sup 233}U({sup 14}N,xn){sup 247{minus}x}Es and {sup 233}U({sup 15}N,xn){sup 248{minus}x}Es reactions were measured for {sup 243}Es, {sup 244}Es and {sup 245}Es at projectile energies between 80 MeV and 100 MeV.

Shaughnessy, Dawn A.

2000-01-05T23:59:59.000Z

189

Prescission neutron multiplicity and fission probability from Langevin dynamics of nuclear fission  

E-Print Network [OSTI]

A theoretical model of one-body nuclear friction which was developed earlier, namely the chaos-weighted wall formula, is applied to a dynamical description of compound nuclear decay in the framework of the Langevin equation coupled with statistical evaporation of light particles and photons. We have used both the usual wall formula friction and its chaos-weighted version in the Langevin equation to calculate the fission probability and prescission neutron multiplicity for the compound nuclei $^{178}$W, $^{188}$Pt, $^{200}$Pb, $^{213}$Fr, $^{224}$Th, and $^{251}$Es. We have also obtained the contributions of the presaddle and postsaddle neutrons to the total prescission multiplicity. A detailed analysis of our results leads us to conclude that the chaos-weighted wall formula friction can adequately describe the fission dynamics in the presaddle region. This friction, however, turns out to be too weak to describe the postsaddle dynamics properly. This points to the need for a suitable explanation for the enhanc...

Chaudhuri, G; Chaudhuri, Gargi; Pal, Santanu

2002-01-01T23:59:59.000Z

190

Time features of delayed neutrons and partial emissive-fission cross sections for the neutron-induced fission of {sup 232}Th nuclei in the energy range 3.2-17.9 MeV  

SciTech Connect (OSTI)

The energy dependence of the relative abundances of delayed neutrons and the energy dependence of the half-lives of their precursors in the neutron-induced fission of {sup 232}Th nuclei in the energy range 3.2-17.9 MeV were measured for the first time. A systematics of the time features of delayed neutrons is developed. This systematics makes it possible to estimate the half-life of delayed-neutron precursors as a function of the nucleonic composition of fissile nuclei by using a single parameter set for all nuclides. The energy dependence of the partial cross sections for emissive fission in the reaction {sup 232}Th(n, f) was analyzed on the basis of data obtained for the relative abundances of delayed neutrons and the aforementioned half-lives and on the basis of the created systematics of the time features of delayed neutrons. It was shown experimentally for the first time that the decrease in the cross section after the reaction threshold in the fission of {sup 232}Th nuclei (it has a pronounced first-chance plateau) is not an exclusion among the already studied uranium, plutonium, and curium isotopes and complies with theoretical predictions obtained for the respective nuclei with allowance for shell, superfluid, and collective effects in the nuclear-level density and with allowance for preequilibrium neutron emission

Roshchenko, V. A., E-mail: roshchenko@ippe.ru; Piksaikin, V. M., E-mail: piksa@ippe.ru; Korolev, G. G.; Egorov, A. S., E-mail: egorov@ippe.r [Institute of Physics and Power Engineering (Russian Federation)

2010-06-15T23:59:59.000Z

191

Argonne National Laboratory 9700 S. Cass Avenue  

E-Print Network [OSTI]

the world's first man-made controlled nuclear chain reaction. · Submarine Thermal Reactor physics critical of Nuclear Fission led to the First Controlled Nuclear Chain Reaction, which led to Commercial and Advanced Reactor Designs The Discovery of Nuclear Fission led to the First Controlled Nuclear Chain Reaction, which

Kemner, Ken

192

Detecting fission from special nuclear material sources  

DOE Patents [OSTI]

A neutron detector system for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. The system includes a graphing component that displays the plot of the neutron distribution from the unknown source over a Poisson distribution and a plot of neutrons due to background or environmental sources. The system further includes a known neutron source placed in proximity to the unknown source to actively interrogate the unknown source in order to accentuate differences in neutron emission from the unknown source from Poisson distributions and/or environmental sources.

Rowland, Mark S. (Alamo, CA); Snyderman, Neal J. (Berkeley, CA)

2012-06-05T23:59:59.000Z

193

New fission valley for /sup 258/Fm and nuclei beyond  

SciTech Connect (OSTI)

Experimental results on the fission properties of nuclei close to /sup 264/Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus /sup 258/Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic energy peaked at about 235 MeV whereas /sup 256/Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic energy peaked at about 200 MeV. Qualitatively, these sudden changes hve been postulated to be due to the emergence of fragment shells in symmetric fission products close to /sup 132/Sn. A quantitative calculation that shows where high-kinetic-energy symmetric fission occurs and why it is associated with a sudden and large decrease in fission half-lives. The study is based on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. The implications of the new fission valley on the stability of the heaviest elements is discussed. 33 refs., 12 figs.

Moeller, P.; Nix, J.R.; Swiatecki, W.J.

1986-01-01T23:59:59.000Z

194

Compilation of fission product yields Vallecitos Nuclear Center  

SciTech Connect (OSTI)

This document is the ninth in a series of compilations of fission yield data made at Vallecitos Nuclear Center in which fission yield measurements reported in the open literature and calculated charge distributions have been utilized to produce a recommended set of yields for the known fission products. The original data with reference sources, as well as the recommended yields are presented in tabular form for the fissionable nuclides U-235, Pu-239, Pu-241, and U-233 at thermal neutron energies; for U-235, U-238, Pu-239, and Th-232 at fission spectrum energies; and U-235 and U-238 at 14 MeV. In addition, U-233, U-236, Pu-240, Pu-241, Pu-242, Np-237 at fission spectrum energies; U-233, Pu-239, Th-232 at 14 MeV and Cf-252 spontaneous fission are similarly treated. For 1979 U234F, U237F, Pu249H, U234He, U236He, Pu238F, Am241F, Am243F, Np238F, and Cm242F yields were evaluated. In 1980, Th227T, Th229T, Pa231F, Am241T, Am241H, Am242Mt, Cm245T, Cf249T, Cf251T, and Es254T are also evaluated.

Rider, B.F.

1980-01-01T23:59:59.000Z

195

PHYSICAL REVIEW VOLUME 183; NUMBER 4 20 J ULY 1969 Single-Particle Theory of Fission*  

E-Print Network [OSTI]

manuscript received 6 December 1968) The single-particle aspects of nuclear fission theories are investigated

196

Active Fusion and Fission Processes on a Fluid Membrane  

E-Print Network [OSTI]

We investigate the steady states and dynamical instabilities resulting from ``particles'' depositing on (fusion) and pinching off (fission) a fluid membrane. These particles could be either small lipid vesicles or isolated proteins. In the stable case, such fusion/fission events suppress long wavelength fluctuations of the membrane. In the unstable case, the membrane shoots out long tubular structures reminiscent of endosomal compartments or folded structures as in internal membranes like the endoplasmic reticulum or Golgi. We argue that these fusion/fission events should be strongly affected by tension.

Madan Rao; Sarasij R C

2001-02-26T23:59:59.000Z

197

Cross section for the subbarrier fission of {sup 244}Cm  

SciTech Connect (OSTI)

The cross section for {sup 244}Cm fission induced by neutrons of energy in the range between 0.07 eV and 20 keV was measured by using the lead slowing-down spectrometer (LSDS-100) of the Institute for Nuclear Research (Russian Academy of Sciences, Moscow). The parameters of the resonance areas were determined for the lowest eight s-wave neutron resonances, and the respective fission widths were evaluated. Also, the parameters of the intermediate structure in the cross section for the subbarrier fission of {sup 244}Cm nuclei were evaluated. The results were compared with available data and recommendations based on evaluations.

Alekseev, A. A.; Bergman, A. A.; Berlev, A. I.; Koptelov, E. A. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation); Samylin, B. F.; Svirin, M. I.; Trufanov, A. M.; Fursov, B. I.; Shorin, V. S., E-mail: shorin@ippe.r [Institute of Physics and Power Engineering (Russian Federation)

2010-09-15T23:59:59.000Z

198

Sensitivity analysis of the fission gas behavior model in BISON.  

SciTech Connect (OSTI)

This report summarizes the result of a NEAMS project focused on sensitivity analysis of a new model for the fission gas behavior (release and swelling) in the BISON fuel performance code of Idaho National Laboratory. Using the new model in BISON, the sensitivity of the calculated fission gas release and swelling to the involved parameters and the associated uncertainties is investigated. The study results in a quantitative assessment of the role of intrinsic uncertainties in the analysis of fission gas behavior in nuclear fuel.

Swiler, Laura Painton; Pastore, Giovanni [Idaho National Laboratory, Idaho Fall, ID; Perez, Danielle [Idaho National Laboratory, Idaho Fall, ID; Williamson, Richard [Idaho National Laboratory, Idaho Fall, ID

2013-05-01T23:59:59.000Z

199

Discovery of a new mode of nuclear fission  

SciTech Connect (OSTI)

We measured the mass and kinetic-energy partitioning in the spontaneous fission of /sup 258/Fm, /sup 259/Md, /sup 260/Md, /sup 258/No, and /sup 260/(104). Surprisingly, these energy distributions were skewed upward or downward from the peak in each case, except for /sup 260/(104), indicating a composite of two energy distributions. We interpret this as a new mode of fission in which there is mixture of liquid-drop-like and fragment-shell-directed symmetric fission.

Hulet, E.K.; Wild, J.F.; Dougan, R.J.; Lougheed, R.W.; Landrum, J.H.; Dougan, A.D.; Schaedel, M.; Hahn, R.L.; Baisden, P.A.; Henderson, C.M.

1986-01-01T23:59:59.000Z

200

Actinide Neutron-Induced Fission Cross Section Measurements At LANSCE  

SciTech Connect (OSTI)

Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications in a wide energy range from sub thermal energies up to 200 MeV. Parallel-plate ionization chambers are used to measure fission cross sections ratios relative to the {sup 235}U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the {sup 233,238}U, {sup 239-242}Pu and {sup 243}Am neutron-induced fission cross sections. Obtained data are presented in comparison with existing evaluations and previous data.

Tovesson, F.; Laptev, A. B. [Los Alamos National Laboratory, Los Alamos NM 87545 (United States); Hill, T. S. [Idaho National Laboratory, Idaho Falls ID 83415 (United States)

2011-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Chemical Reactions in DSMC  

SciTech Connect (OSTI)

DSMC simulations of chemically reacting gas flows have generally employed procedures that convert the macroscopic chemical rate equations to reaction cross-sections at the microscopic level. They therefore depend on the availability of experimental data that has been fitted to equations of the Arrhenius form. This paper presents a physical model for dissociation and recombination reactions and a phenomenological model for exchange and chain reactions. These are based on the vibrational states of the colliding molecules and do not require any experimentally-based data. The simplicity of the models allows the corresponding rate equations to be written down and, while these are not required for the implementation of the models, they facilitate their validation. The model is applied to a typical hypersonic atmospheric entry problem and the results are compared with the corresponding results from the traditional method. It is also used to investigate both spontaneous and forced ignition as well as the structure of a deflagration wave in an oxygen-hydrogen mixture.

Bird, G. A. [GAB Consulting Pty Ltd, 144/110 Sussex Street, Sydney NSW 2000 (Australia)

2011-05-20T23:59:59.000Z

202

Safe Chain Saw Operation.  

E-Print Network [OSTI]

Electric-powered saws start instantly, are rela tively quiet, have no exhaust fumes or hot muffier, carry no fuel and are generally less expensive than gasoline saws. However, electric saws are limited in size (usually under 14-inch bars) and reach only... AND FELLING WEDGES I EXTI~bRJiSHER ~ ~ CHAIN FILING ~ ~ TOOLS FUEL CAN AND FUNNEL SHARP AX Figure 3. Use proper equipment to help you do the job safely. 2 /. SLEDGE HAMMER SHOVEL Special cautions: Electrically-powered chain saws re quire special...

Nelson, Gary S.

1982-01-01T23:59:59.000Z

203

Measurement/Evaluation Techniques and Nuclear Data Associated with Fission of 239Pu by Fission Spectrum Neutrons  

SciTech Connect (OSTI)

This Panel was chartered to review and assess new evaluations of work on fission product data, as well as the evaluation process used by the two U.S. nuclear weapons physics laboratories. The work focuses on fission product yields resulting from fission spectrum neutrons incident on plutonium, and includes data from measurements that had not been previously published as well as new or revised fission product cumulative yield data, and related quantities such as Q values and R values. This report documents the Panel's assessment of the work presented by Los Alamos National Laboratory (LANL) and Lawrence Livermore National Laboratory (LLNL). Based on the work presented we have seven key observations: (1) Experiments conducted in the 1970s at LANL, some of which were performed in association with a larger, NIST-led, program, have recently been documented. A preliminary assessment of this work, which will be referred to in this document as ILRR-LANL, shows it to be technically sound. (2) LLNL has done a thorough, unbiased review and evaluation of the available literature and is in the process of incorporating the previously unavailable LANL data into its evaluation of key fission product yields. The results of the LLNL effort, which includes a preliminary evaluation of the ILRR-LANL data, have been documented. (3) LANL has also conducted an evaluation of fission product yields for fission spectrum neutrons on plutonium including a meta-analysis of benchmark data as part of a planned upgrade to the ENDF/B compilation. We found that the approach of using meta-analysis provides valuable additional insight for evaluating the sparse data sets involved in this assessment. (4) Both laboratories have provided convincing evidence for energy dependence in the fission product yield of {sup 147}Nd produced from the bombardment of {sup 239}Pu with fission spectrum neutrons over an incident neutron energy range of 0.2 to 1.9 MeV. (5) Consistent, complete, and explicit treatment of both systematic and statistical uncertainties, including correlations, are critical to the assessment of both the experimental measurements (due to variations between experimental techniques, irradiation conditions, calibration procedures, etc.), and the evaluation of those experiments to extract fundamental nuclear data. A clear example of the importance of uncertainty analysis is in the justification for energy-dependent {sup 147}Nd fission product yield, where the magnitude of the effect is comparable to the uncertainties of the individual fission product yield measurements. Both LANL and LLNL are committed to the inclusion of full uncertainty analysis in their evaluations. (6) The Panel reviewed in detail two methods for determining/evaluating fission product yields from which fission assessments can be made: the K factor method and high-resolution gamma spectroscopy (both described more fully in Sections 3 and 4). The panel concluded that fission product yields, and thus fission assessments, derived using either approach are equally valid, provided that the data were obtained from well understood, direct fission measurements and that the key underlying calibrations and/or data are valid for each technique. (7) The Panel found the process of peer review of the two complementary but independent methods to be an extremely useful exercise. Although work is still ongoing and the numbers presented to the Panel may change slightly, both groups are now in much better agreement on not just one, but four key fission product yields. The groups also have a better appreciation of the strengths and weaknesses of each other's methods.

Baisden, P; Bauge, E; Ferguson, J; Gilliam, D; Granier, T; Jeanloz, R; McMillan, C; Robertson, D; Thompson, P; Verdon, C; Wilkerson, C; Young, P

2010-03-16T23:59:59.000Z

204

In-cell reaction rate distributions and cell-average reaction rates in fast critical assemblies  

SciTech Connect (OSTI)

Measurements are described for determining average values of fission rates in /sup 235/U, /sup 238/U and /sup 239/Pu and capture rates in /sup 238/U for heterogeneous cells used to construct fast critical assemblies. The measurements are based on irradiations of foils of /sup 238/U, /sup 235/U and /sup 239/Pu with counting of fission and capture products using gamma-ray spectroscopy. Both plate and pin cells are considered. Procedures are described for inferring cell-average reaction rate values from a single foil location based on a cell using a quantity called a cell factor. Cell factors are determined from special measurements in which several foils are irradiated within a cell. Comparisons are presented between cell factors determined by measurements and by Monte Carlo calculations which lend credibility to the measurement procedures.

Brumbach, S.B.; Gasidlo, J.M.

1985-08-01T23:59:59.000Z

205

Half life for spontaneous fission of curium-245  

SciTech Connect (OSTI)

A sample of curium-245 of extremely high enrichment was obtained with an electromagnetic separator. The half-life for spontaneous fission was determined by measuring the rate of alpha decay. (AIP)

Druzhinin, A.A.; Polynov, V.N.; Vesnovskii, S.P.; Korochkin, A.M.; Lbov, A.A.; Nikitin, E.A.

1985-02-01T23:59:59.000Z

206

Spontaneous fission half-lives for ground state nuclides  

SciTech Connect (OSTI)

Measurements of the spontaneous fission half-lives of nuclides of elements Z = 90 to 107 have been compiled and evaluated. Recommended values are presented. 126 refs., 96 tabs.

Holden, N.E. (Brookhaven National Lab., Upton, NY (United States)); Hoffman, D.C. (Lawrence Berkeley Lab., CA (United States))

1991-01-01T23:59:59.000Z

207

Total Prompt Energy Release in the Neutron-Induced Fission  

E-Print Network [OSTI]

This study addresses, for the first time, the total prompt energy release and its components for the fission of 235 U, 238 U, and 239 Pu as a function of the kinetic energy of the neutron inducing the fission. The components are extracted from experimental measurements, where they exist, together with model-dependent calculation, interpolation, and extrapolation. While the components display clear dependencies upon the incident neutron energy, their sums display only weak, yet definite, energy dependencies. Also addressed is the total prompt energy deposition in fission for the same three systems. Results are presented in equation form. New measurements are recommended as a consequence of this study. Key words: Energy release and energy deposition in neutron-induced fission,

D. G. Madland

2006-01-01T23:59:59.000Z

208

June 2014 Most Viewed Documents for Fission And Nuclear Technologies...  

Office of Scientific and Technical Information (OSTI)

June 2014 Most Viewed Documents for Fission And Nuclear Technologies Behavior of spent nuclear fuel in water pool storage Johnson, A.B. Jr. (1977) 78 Estimation of gas leak rates...

209

July 2013 Most Viewed Documents for Fission And Nuclear Technologies...  

Office of Scientific and Technical Information (OSTI)

July 2013 Most Viewed Documents for Fission And Nuclear Technologies Science Subject Feed Estimation of gas leak rates through very small orifices and channels. From sealed PuO...

210

Singlet exciton fission : applications to solar energy harvesting  

E-Print Network [OSTI]

Singlet exciton fission transforms a single molecular excited state into two excited states of half the energy. When used in solar cells it can double the photocurrent from high energy photons increasing the maximum ...

Thompson, Nicholas John

2014-01-01T23:59:59.000Z

211

NUFinancials Supply Chain  

E-Print Network [OSTI]

NUFinancials Supply Chain FMS801 & 803 Purchasing Glossary 03/31/2010 © 2010 Northwestern University FMS801 & 803 1 Purchasing Glossary Guide to terms used in iBuyNU and NUFinancials purchasing Term, faculty salary, office supplies. Similar to CUFS Object Code, Revenue Source, and Balance Sheet. Note

Shull, Kenneth R.

212

Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction | National  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsing Zirconia NanoparticlesSmartAffects the Future EnergyEnolSpectrometry Results

213

Description of true and delayed ternary nuclear fission accompanied by the emission of various third particles  

SciTech Connect (OSTI)

The mechanisms and the features of the main types of nuclear ternary fission (that is, true ternary fission, in which a third particle is emitted before the rupture of the fissioning nucleus into fragments, and delayed ternary fission, in which a third particle is emitted from fission fragments going apart) are investigated within quantum-mechanical fission theory. The features of T-odd asymmetry in true ternary nuclear fission induced by cold polarized neutrons are investigated for the cases where alpha particles, prescission neutrons, and photons appear as third particles emitted by fissioning nuclei, the Coriolis interaction of the spin of the polarized fissioning nucleus with the spin of the third particle and the interference between the fission amplitudes for neutron resonances excited in the fissioning nucleus in the case of projectile-neutron capture being taken into account. For the cases where third particles emitted by fission fragments are evaporated neutrons or photons, T-odd asymmetries in delayed ternary nuclear fission induced by cold polarized neutrons are analyzed with allowance for the mechanism of pumping of large fission-fragment spins oriented orthogonally to the fragment-emission direction and with allowance for the interference between the fission amplitudes for neutron resonances.

Kadmensky, S. G., E-mail: kadmensky@vsu.ru; Kadmensky, S. S.; Lyubashevsky, D. E. [Voronezh State University (Russian Federation)

2010-08-15T23:59:59.000Z

214

Cross section for fast neutron induced /sup 243/Cm fission  

SciTech Connect (OSTI)

The authors discuss a method for measuring the cross section of the fission of curium 243 which either eliminates or corrects for the interference arising from sister isotopes or from the half-life spontaneous fission of this isotope. Soda-lime glass was used as the detector material and uranium 235 as the calibration standard. The irradiation facility is described. Error estimates are given.

Fomushkin, E.F.; Novoselov, G.F.; Vinogradov, Yu.I.; Vyachin, V.N.; Gavrilov, V.V.; Koshelev, A.S.; Polynov, V.N.; Surin, V.M.; Shvetsov, A.M.

1987-10-01T23:59:59.000Z

215

Present Status of Fission Research Based on TDDFT  

E-Print Network [OSTI]

Fission resulting from collision of atomic nuclei is systematically investigated based on time-dependent density functional calculations. Time-dependent density functional theory (TDDFT) is a framework, which enables us to treat quantum many-body dynamics with nucleon degrees of freedom. In this article a theoretical framework called Composite-Nucleus Constrained TDDFT is introduced, and charge equilibrium hypothesis for collision fission dynamics is examined.

Yoritaka Iwata

2015-01-28T23:59:59.000Z

216

Evaluation and compilation of fission product yields 1993  

SciTech Connect (OSTI)

This document is the latest in a series of compilations of fission yield data. Fission yield measurements reported in the open literature and calculated charge distributions have been used to produce a recommended set of yields for the fission products. The original data with reference sources, and the recommended yields axe presented in tabular form. These include many nuclides which fission by neutrons at several energies. These energies include thermal energies (T), fission spectrum energies (F), 14 meV High Energy (H or HE), and spontaneous fission (S), in six sets of ten each. Set A includes U235T, U235F, U235HE, U238F, U238HE, Pu239T, Pu239F, Pu241T, U233T, Th232F. Set B includes U233F, U233HE, U236F, Pu239H, Pu240F, Pu241F, Pu242F, Th232H, Np237F, Cf252S. Set C includes U234F, U237F, Pu240H, U234HE, U236HE, Pu238F, Am241F, Am243F, Np238F, Cm242F. Set D includes Th227T, Th229T, Pa231F, Am241T, Am241H, Am242MT, Cm245T, Cf249T, Cf251T, Es254T. Set E includes Cf250S, Cm244S, Cm248S, Es253S, Fm254S, Fm255T, Fm256S, Np237H, U232T, U238S. Set F includes Cm243T, Cm246S, Cm243F, Cm244F, Cm246F, Cm248F, Pu242H, Np237T, Pu240T, and Pu242T to complete fission product yield evaluations for 60 fissioning systems in all. This report also serves as the primary documentation for the second evaluation of yields in ENDF/B-VI released in 1993.

England, T.R.; Rider, B.F.

1995-12-31T23:59:59.000Z

217

Method to calibrate fission chambers in Campbelling mode  

SciTech Connect (OSTI)

Fission chambers are neutron detectors which are widely used to instrument experimental reactors such as material testing reactors or zero power reactors. In the presence of a high level mixed gamma and neutron flux, fission chambers can be operated in Campbelling mode (also known as 'fluctuation mode' or 'mean square voltage mode') to provide reliable and precise neutron related measurements. Fission chamber calibration in Campbelling mode (in terms of neutron flux) is usually done empirically using a calibrated reference detector. A major drawback of this method is that calibration measurements have to be performed in a neutron environment very similar to the one in which the calibrated detector will be used afterwards. What we propose here is a different approach based on characterizing the fission chamber response in terms of fission rate. This way, the detector calibration coefficient is independent from the neutron spectrum and can be determined prior to the experiment. The fissile deposit response to the neutron spectrum can then be assessed independently by other means (experimental or numerical). In this paper, the response of CEA made miniature fission chambers in Campbelling mode is studied. We use a theoretical model of the signal to calculate the calibration coefficient. Input parameters of the model come from statistical distribution of individual pulses. Supporting measurements have been made in the CEA Cadarache zero power reactor MINERVE. Results are compared to an empirical Campbelling mode calibration.

Benoit Geslot; Troy C. Unruh; Philippe Filliatre; Christian Jammes; Jacques Di Salvo; Stéphane Bréaud; Jean-François Villard

2011-06-01T23:59:59.000Z

218

Symmetric and asymmetric fission modes in proton-induced fission at 660 MeV of {sup 238}U  

SciTech Connect (OSTI)

Fission product cross sections of intermediate-energy fission of {sup 238}U were used in order to construct the charge and mass yield distributions. Enriched target of {sup 238}U was irradiated by proton beam with energy 660 MeV for several hours at the LNP Phasotron, Joint Institute for Nuclear Research (JINR), Dubna, Russia. The charge distribution of the fission fragments was analyzed for calculation of isobaric cross sections. The mass yield curves were expanded into symmetric and asymmetric components according multimodal fission approach. The fissility values of actinides were calculated at given proton energy. The obtained results have been compared to the same data for targets {sup 237}Np and {sup 241}Am.

Balabekyan, A. R., E-mail: balabekyan@ysu.am; Karapetyan, G. S. [Yerevan State University (Armenia); Demekhina, N. A.; Adam, J. [JINR (Russian Federation); Katovsky, K. [Czech Technical University in Prague, Department of Nuclear Reactors (Czech Republic)

2010-11-15T23:59:59.000Z

219

SOURCES-3A: A code for calculating ({alpha}, n), spontaneous fission, and delayed neutron sources and spectra  

SciTech Connect (OSTI)

In many systems, it is imperative to have accurate knowledge of all significant sources of neutrons due to the decay of radionuclides. These sources can include neutrons resulting from the spontaneous fission of actinides, the interaction of actinide decay {alpha}-particles in ({alpha},n) reactions with low- or medium-Z nuclides, and/or delayed neutrons from the fission products of actinides. Numerous systems exist in which these neutron sources could be important. These include, but are not limited to, clean and spent nuclear fuel (UO{sub 2}, ThO{sub 2}, MOX, etc.), enrichment plant operations (UF{sub 6}, PuF{sub 4}, etc.), waste tank studies, waste products in borosilicate glass or glass-ceramic mixtures, and weapons-grade plutonium in storage containers. SOURCES-3A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides in homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material) and in interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material). The code is also capable of calculating the neutron production rates due to ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem.

Perry, R.T.; Wilson, W.B.; Charlton, W.S.

1998-04-01T23:59:59.000Z

220

Early Flight Fission Test Facilities (EFF-TF) To Support Near-Term Space Fission Systems  

SciTech Connect (OSTI)

Through hardware based design and testing, the EFF-TF investigates fission power and propulsion component, subsystems, and integrated system design and performance. Through demonstration of systems concepts (designed by Sandia and Los Alamos National Laboratories) in relevant environments, previous non-nuclear tests in the EFF-TF have proven to be a highly effective method (from both cost and performance standpoint) to identify and resolve integration issues. Ongoing research at the EFF-TF is geared towards facilitating research, development, system integration, and system utilization via cooperative efforts with DOE labs, industry, universities, and other NASA centers. This paper describes the current efforts for 2003.

Van Dyke, Melissa [Marshall Space Flight Center, National Aeronautics and Space Administration, Huntsville, Alabama, 35812 (United States)

2004-02-04T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Ring fission of anthracene by a eukaryota  

SciTech Connect (OSTI)

Ligninolytic fungi are unique among eukaryotes in their ability to degrade polycyclic aromatic hydrocarbons (PAHs), but the mechanism for this process is unknown. Although certain PAHs are oxidized in vitro by the fungal lignin peroxidases (LiPs) that catalyze ligninolysis, it has never been shown that LiPs initiate PAH degradation in vivo. To address these problems, the metabolism of anthracene (AC) and its in vitro oxidation product, 9,10-anthraquinone (AQ), was examined by chromatographic and isotope dilution techniques in Phanerochaete chrysosporium. The fungal oxidation of AC to AQ was rapid, and both AC and AQ were significantly mineralized. Both compounds were cleaved by the fungus to give the same ring-fission metabolite, phthalic acid, and phthalate production from AQ was shown to occur only under ligninolytic culture conditions. These results show that the major pathway for AC degradation in Phanerochaete proceeds AC -> AQ -> phthalate + CO2 and that it is probably mediated by LiPs and other enzymes of ligninolytic metabolism.

Hammel, K.E.; Green, B.; Gai, W.Z.

1993-01-01T23:59:59.000Z

222

Ring fission of anthracene by a eukaryote  

SciTech Connect (OSTI)

Ligninolytic fungi are unique among eukaryotes in their ability to degrade polycyclic aromatic hydrocarbons (PAHs), but the mechanism for this process is unknown. Although certain PAHs are oxidized in vitro by the fungal lignin peroxidases (LiPs) that catalyze ligninolysis, it has never been shown that LiPs initiate PAH degradation in vivo. To address these problems, the metabolism of anthracene (AC) and its in vitro oxidation product, 9,10-anthraquinone (AQ), was examined by chromatographic and isotope dilution techniques in Phanerochaete chrysosporium. The fungal oxidation of AC to AQ was rapid, and both AC and AQ were significantly mineralized. Both compounds were cleaved by the fungus to give the same ring-fission metabolite, phthalic acid, and phthalate production from AQ was shown to occur only under ligninolytic culture conditions. These results show that the major pathway for AC degradation in Phanerochaete proceeds AC {yields} AQ {yields} phthalate + CO{sub 2} and that it is probably mediated by LiPs and other enzymes of ligninolytic metabolism.

Hammel, K.E.; Green, B.; Wen Zhi Gai (State Univ. of New York, Syracuse (United States))

1991-12-01T23:59:59.000Z

223

PoS(NIC-IX)040 Direct reactions in/for astrophysics  

E-Print Network [OSTI]

on the opposite ends of the energy scale of nuclear reactions: (a) the very high and (b) the very low relative scale are the low energy reactions of importance for stellar evolution. Chains of nuclear reactions lead reactions methods have been developed and applied to extract low-energy astrophysical S

Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

224

Complex particle and light fragment emission in the cascade-excitation model of nuclear reactions  

SciTech Connect (OSTI)

A brief description of our improvements and refinements that led from the CEM95 version of the Cascade-Exciton Model (CEM) code to CEM97 and to CEM2k is given. The increased accuracy and predictive power of the code CEM2k are shown by several examples. To describe fission and light-fragment (heavier than {sup 4}He) production, the CEM2k code has been merged with the GEM2 code of Furihata. We present some results on proton-induced fragmentation and fission reactios predicted by this extended version of CEM2k. We show that merging CEM2k with GEM2 allows us to describe many fission and fragmentation reactions in addition to the spallation reactions which are already relatively well described.

Mashnik, S. G. (Stepan G.); Sierk, A. J. (Arnold J.); Gudima, K. K. (Konstantin K.)

2002-01-01T23:59:59.000Z

225

The Tourism Global Value Chain  

E-Print Network [OSTI]

The Tourism Global Value Chain ECONOMIC UPGRADING AND WORKFORCE DEVELOPMENT Michelle Christian 2011 CENTER on GLOBALIZATION, GOVERNANCE & COMPETITIVENESS #12;The Tourism Global Value Chain: Economic: November 17, 2011 #12;The Tourism Global Value Chain: Economic Upgrading and Workforce Development i Table

Richardson, David

226

Environmental decision making: supply-chain considerations  

E-Print Network [OSTI]

manufacturing environmental impact and enable the reductionthe supply chain (3) environmental impact and cost must bethe supply chain’s environmental impact and flexibility (

Reich-Weiser, Corinne; Dornfeld, David

2008-01-01T23:59:59.000Z

227

The Future of Energy from Nuclear Fission  

SciTech Connect (OSTI)

Nuclear energy is an important part of our current global energy system, and contributes to supplying the significant demand for electricity for many nations around the world. There are 433 commercial nuclear power reactors operating in 30 countries with an installed capacity of 367 GWe as of October 2011 (IAEA PRIS, 2011). Nuclear electricity generation totaled 2630 TWh in 2010 representing 14% the world’s electricity generation. The top five countries of total installed nuclear capacity are the US, France, Japan, Russia and South Korea at 102, 63, 45, 24, and 21 GWe, respectively (WNA, 2012a). The nuclear capacity of these five countries represents more than half, 68%, of the total global nuclear capacity. The role of nuclear power in the global energy system today has been motivated by several factors including the growing demand for electric power, the regional availability of fossil resources and energy security concerns, and the relative competitiveness of nuclear power as a source of base-load electricity. There is additional motivation for the use of nuclear power because it does not produce greenhouse gas (GHG) emissions or local air pollutants during its operation and contributes to low levels of emissions throughout the lifecycle of the nuclear energy system (Beerten, J. et. al., 2009). Energy from nuclear fission primarily in the form of electric power and potentially as a source of industrial heat could play a greater role for meeting the long-term growing demand for energy worldwide while addressing the concern for climate change from rising GHG emissions. However, the nature of nuclear fission as a tremendously compact and dense form of energy production with associated high concentrations of radioactive materials has particular and unique challenges as well as benefits. These challenges include not only the safety and cost of nuclear reactors, but proliferation concerns, safeguard and storage of nuclear materials associated with nuclear fuel cycles. In March of 2011, an unprecedented earthquake of 9 magnitude and ensuing tsunami off the east coast of Japan caused a severe nuclear accident in Fukushima, Japan (Prime Minister of Japan and His Cabinet, 2011). The severity of the nuclear accident in Japan has brought about a reinvestigation of nuclear energy policy and deployment activities for many nations around the world, most notably in Japan and Germany (BBC, 2011; Reuter, 2011). The response to the accident has been mixed and its full impact may not be realized for many years to come. The nuclear accident in Fukushima, Japan has not directly affected the significant on-going nuclear deployment activities in many countries. China, Russia, India, and South Korea, as well as others, are continuing with their deployment plans. As of October 2011, China had the most reactors under construction at 27, while Russia, India, and South Korea had 11, 6, and 5 reactors under construction, respectively (IAEA PRIS, 2011). Ten other nations have one or two reactors currently under construction. Many more reactors are planned for future deployment in China, Russia, and India, as well as in the US. Based on the World Nuclear Association’s data, the realization of China’s deployment plan implies that China will surpass the US in total nuclear capacity some time in the future.

Kim, Son H.; Taiwo, Temitope

2013-04-13T23:59:59.000Z

228

Directional measurements for sources of fission neutrons  

SciTech Connect (OSTI)

Although penetrating neutron and gamma-ray emissions arguably provide the most effective signals for locating sources of nuclear radiation, their relatively low fluxes make searching for radioactive materials a tedious process. Even assuming lightly shielded sources and detectors with large areas and high efficiencies, estimated counting times can exceed several minutes for source separations greater than ten meters. Because determining the source position requires measurements at several locations, each with its own background, the search procedure can be lengthy and difficult to automate. Although directional measurements can be helpful, conventional collimation reduces count rates and increases the detector size and weight prohibitively, especially for neutron instruments. We describe an alternative approach for locating radiation sources that is based on the concept of a polarized radiation field. In this model, the presence of a source adds a directional component to the randomly oriented background radiation. The net direction of the local field indicates the source angle, and the magnitude provides an estimate of the distance to the source. The search detector is therefore seen as a device that responds to this polarized radiation field. Our proposed instrument simply substitutes segmented detectors for conventional single-element ones, so it requires little or no collimating material or additional weight. Attenuation across the detector creates differences in the count rates for opposite segments, whose ratios can be used to calculate the orthogonal components of the polarization vector. Although this approach is applicable to different types of radiation and detectors, in this report we demonstrate its use for sources of fission neutrons by using a prototype fast-neutron detector, which also provides background-corrected energy spectra for the incident neutrons.

Byrd, R.C.; Auchampaugh, G.F.; Feldman, W.C.

1993-11-01T23:59:59.000Z

229

Predicting the production of neutron rich heavy nuclei in multi-nucleon transfer reactions using GRAZING-F  

E-Print Network [OSTI]

Background: Multi-nucleon transfer reactions have recently attracted attention as a possible path to the synthesis of new neutron-rich heavy nuclei. Purpose: We study transfer reactions involving massive nuclei with the intention of understanding if the semi-classical model GRAZING coupled to an evaporation and fission competition model can satisfactory reproduce experimental data on transfer reactions in which fission plays a role. Methods: We have taken the computer code GRAZING and have added fission competition to it (GRAZING-F) using our current understanding of $\\Gamma_n/\\Gamma_f$, fission barriers and level densities. Results: The code GRAZING-F seems to satisfactory reproduce experimental data for $+1p$, $+2p$ and $+3p$ transfers, but has limitations in reproducing measurements of larger above-target and below-target transfers. Nonetheless, we use GRAZING-F to estimate production rates of neutron-rich $N=126$ nuclei, actinides and transactinides. Conclusions: The GRAZING code, with appropriate modifications to account for fission decay as well as neutron emission by excited primary fragments, does not predict large cross sections for multi-nucleon transfer reactions leading to neutron-rich transactinide nuclei, but predicts opportunities to produce new neutron-rich actinide isotopes.

R. Yanez; W. Loveland

2015-03-03T23:59:59.000Z

230

Neutron source capability assessment for cumulative fission yields measurements  

SciTech Connect (OSTI)

A recent analysis of high-quality cumulative fission yields data for Pu-239 published in the peer-reviewed literature showed that the quoted experimental uncertainties do not allow a clear statement on how the fission yields vary as a function of energy. [Prussin2009] To make such a statement requires a set of experiments with well 'controlled' and understood sources of experimental errors to reduce uncertainties as low as possible, ideally in the 1 to 2% range. The Inter Laboratory Working Group (ILWOG) determined that Directed Stockpile Work (DSW) would benefit from an experimental program with the stated goal to reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Following recent discussions between Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), there is a renewed interest in developing a concerted experimental program to measure fission yields in a neutron energy range from thermal energy (0.025 eV) to 14 MeV with an emphasis on discrete energies from 0.5 to 4 MeV. Ideally, fission yields would be measured at single energies, however, in practice there are only 'quasi-monoenergetic' neutrons sources of finite width. This report outlines a capability assessment as of June 2011 of available neutron sources that could be used as part of a concerted experimental program to measure cumulative fission yields. In a framework of international collaborations, capabilities available in the United States, at the Atomic Weapons Establishment (AWE) in the United Kingdom and at the Commissariat Energie Atomique (CEA) in France are listed. There is a need to develop an experimental program that will reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Fission and monoenergetic neutron sources are available that could support these fission yield experiments in the US, as well as at AWE and CEA. Considerations that will impact the final choice of experimental venues are: (1) Availability during the timeframe of interest; (2) Ability to accommodate special nuclear materials; (3) Cost; (4) Availability of counting facilities; and (5) Expected experimental uncertainties.

Descalle, M A; Dekin, W; Kenneally, J

2011-04-06T23:59:59.000Z

231

Kinetic energy deficit in the symmetric fission of /sup 259/Md. [Light particle emission in /sup 256/Fm fission  

SciTech Connect (OSTI)

The fragment energies of about 725 coincidence events have now been observed in the spontaneous fission (SF) decay of 105-min /sup 259/Md since its discovery in 1977. The fission of /sup 259/Md is characterized by a symmetric mass distribution, similar to those of /sup 258/Fm and /sup 259/Fm, but with a broad total kinetic energy (anti TKE) distribution which peaks at about 195 MeV, in contrast to those of /sup 258/Fm and /sup 259/Fm, for which the anti TKE is about 240 MeV. This kinetic energy deficit, approx. 40 MeV, has been postulated to be due to the emission of hydrogen-like particles by /sup 259/Md at the scission point in a large fraction of the fissions, leaving the residual fissioning nucleus with 100 protons. The residual nucleus would then be able to divide into two ultrastable tin-like fission fragments, but with less kinetic energy than that observed in the SF of /sup 258/Fm and /sup 259/Fm, because of binding-energy losses and a reduction in the Coulomb repulsion of the major fragments. To test this hypothesis, counter-telescope experiments aimed at detecting and identifying these light particles were performed. In 439 SF events 3 + 3 protons of the appropriate energy were observed, too few to account for the kinetic energy deficit in the fission of /sup 259/Md. There seems to be no explanation for this problem within the framework of current fission theory. These results are discussed along with preliminary measurements of light-particle emission in the SF of /sup 256/Fm. 5 figures.

Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Dougan, R.J.; Mustafa, M.G.

1980-10-01T23:59:59.000Z

232

Initial Back-to-Back Fission Chamber Testing in ATRC  

SciTech Connect (OSTI)

Development and testing of in-pile, real-time neutron sensors for use in Materials Test Reactor experiments is an ongoing project at Idaho National Laboratory. The Advanced Test Reactor National Scientific User Facility has sponsored a series of projects to evaluate neutron detector options in the Advanced Test Reactor Critical Facility (ATRC). Special hardware was designed and fabricated to enable testing of the detectors in the ATRC. Initial testing of Self-Powered Neutron Detectors and miniature fission chambers produced promising results. Follow-on testing required more experiment hardware to be developed. The follow-on testing used a Back-to-Back fission chamber with the intent to provide calibration data, and a means of measuring spectral indices. As indicated within this document, this is the first time in decades that BTB fission chambers have been used in INL facilities. Results from these fission chamber measurements provide a baseline reference for future measurements with Back-to-Back fission chambers.

Benjamin Chase; Troy Unruh; Joy Rempe

2014-06-01T23:59:59.000Z

233

Fission gas release restrictor for breached fuel rod  

DOE Patents [OSTI]

In the event of a breach in the cladding of a rod in an operating liquid metal fast breeder reactor, the rapid release of high-pressure gas from the fission gas plenum may result in a gas blanketing of the breached rod and rods adjacent thereto which impairs the heat transfer to the liquid metal coolant. In order to control the release rate of fission gas in the event of a breached rod, the substantial portion of the conventional fission gas plenum is formed as a gas bottle means which includes a gas pervious means in a small portion thereof. During normal reactor operation, as the fission gas pressure gradually increases, the gas pressure interiorly of and exteriorly of the gas bottle means equalizes. In the event of a breach in the cladding, the gas pervious means in the gas bottle means constitutes a sufficient restriction to the rapid flow of gas therethrough that under maximum design pressure differential conditions, the fission gas flow through the breach will not significantly reduce the heat transfer from the affected rod and adjacent rods to the liquid metal heat transfer fluid flowing therebetween.

Kadambi, N. Prasad (Gaithersburg, MD); Tilbrook, Roger W. (Monroeville, PA); Spencer, Daniel R. (Unity Twp., PA); Schwallie, Ambrose L. (Greensburg, PA)

1986-01-01T23:59:59.000Z

234

Laser Inertial Fusion-based Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System  

E-Print Network [OSTI]

aspects of a hybrid fusion-fission energy system called theof a Hybrid Fusion-Fission Nuclear Energy System by Kevinof a Hybrid Fusion-Fission Nuclear Energy System by Kevin

Kramer, Kevin James

2010-01-01T23:59:59.000Z

235

Supply Chain Analysis Center for Transportation Analysis  

E-Print Network [OSTI]

Supply Chain Analysis Center for Transportation Analysis 2360 Cherahala Boulevard Knoxville, TN experience in supply chain analysis and automated support for supply chain systems. ORNL's Capabilities Optimization modeling for supply chain systems, including: Facility number and location analysis

236

Deep Atomic Binding (DAB) Hypothesis: A New Approach of Fission Product Chemistry  

SciTech Connect (OSTI)

Former studies assumed that, after fission process occurs, the highly ionized new born atoms (20-22 positive charge), ionize the media in which they pass through before becoming stable atoms in a manner similar to 4-MeV ?-particles. Via ordinary chemical reactions with the surroundings, each stable atom has a probability to form chemical compound. Since there are about 35 different elemental atoms created through fission processes, a large number of chemical species were suggested to be formed. But, these suggested chemical species were not found in the environment after actual releases of FP during accidents like TMI (USA, 1979), and Chernobyl (former USSR, 1986), also the models based on these suggested reactions and species could not interpret the behavior of these actual species. It is assumed here that the ionization states of the new born atoms and the long term high temperature were not dealt with in an appropriate way and they were the reasons of former models failure. Our new approach of Deep Atomic Binding (DAB) based on the following: 1-The new born atoms which are highly ionized, 10-12 electrons associated with each nucleus, having a large probability to create bonds between them to form molecules. These bonds are at the L, or M shells, and we call it DAB. 2-The molecules stay in the reactor at high temperatures for long periods, so they undergo many stages of composition and decomposition to form giant molecules. By applying DAB approach, field data from Chernobyl, TMI and nuclear detonations could be interpreted with a wide coincidence resulted. (author)

Ajlouni, Abdul-Wali M.S. [Ministry of Energy and Mineral Resources (Jordan)

2006-07-01T23:59:59.000Z

237

Next Generation Nuclear Plant Phenomena Identification and Ranking Tables (PIRTs) Volume 3: Fission-Product Transport and Dose PIRTs  

SciTech Connect (OSTI)

This Fission Product Transport (FPT) Phenomena Identification and Ranking Technique (PIRT) report briefly reviews the high-temperature gas-cooled reactor (HTGR) FPT mechanisms and then documents the step-by-step PIRT process for FPT. The panel examined three FPT modes of operation: (1) Normal operation which, for the purposes of the FPT PIRT, established the fission product circuit loading and distribution for the accident phase. (2) Anticipated transients which were of less importance to the panel because a break in the pressure circuit boundary is generally necessary for the release of fission products. The transients can change the fission product distribution within the circuit, however, because temperature changes, flow perturbations, and mechanical vibrations or shocks can result in fission product movement. (3) Postulated accidents drew the majority of the panel's time because a breach in the pressure boundary is necessary to release fission products to the confinement. The accidents of interest involved a vessel or pipe break, a safety valve opening with or without sticking, or leak of some kind. Two generic scenarios were selected as postulated accidents: (1) the pressurized loss-of-forced circulation (P-LOFC) accident, and (2) the depressurized loss-of-forced circulation (D-LOFC) accidents. FPT is not an accident driver; it is the result of an accident, and the PIRT was broken down into a two-part task. First, normal operation was seen as the initial starting point for the analysis. Fission products will be released by the fuel and distributed throughout the reactor circuit in some fashion. Second, a primary circuit breach can then lead to their release. It is the magnitude of the release into and out of the confinement that is of interest. Depending on the design of a confinement or containment, the impact of a pressure boundary breach can be minimized if a modest, but not excessively large, fission product attenuation factor can be introduced into the release path. This exercise has identified a host of material properties, thermofluid states, and physics models that must be collected, defined, and understood to evaluate this attenuation factor. The assembled PIRT table underwent two iterations with extensive reorganization between meetings. Generally, convergence was obtained on most issues, but different approaches to the specific physics and transport paths shade the answers accordingly. The reader should be cautioned that merely selecting phenomena based on high importance and low knowledge may not capture the true uncertainty of the situation. This is because a transport path is composed of several serial linkages, each with its own uncertainty. The propagation of a chain of modest uncertainties can lead to a very large uncertainty at the end of a long path, resulting in a situation that is of little regulatory guidance.

Morris, Robert Noel [ORNL

2008-03-01T23:59:59.000Z

238

Sputtering yield of Pu bombarded by fission Fragments from Cf  

SciTech Connect (OSTI)

We present results on the yield of sputtering of Pu atoms from a Pu foil, bombarded by fission fragments from a {sup 252}Cf source in transmission geometry. We have found the number of Pu atoms/incoming fission fragments ejected to be 63 {+-} 1. In addition, we show measurements of the sputtering yield as a function of distance from the central axis, which can be understood as an angular distribution of the yield. The results are quite surprising in light of the fact that the Pu foil is several times the thickness of the range of fission fragment particles in Pu. This indicates that models like the binary collision model are not sufficient to explain this behavior.

Danagoulian, Areg [Los Alamos National Laboratory; Klein, Andreas [Los Alamos National Laboratory; Mcneil, Wendy V [Los Alamos National Laboratory; Yuan, Vincent W [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

239

Neutron emission and fragment yield in high-energy fission  

SciTech Connect (OSTI)

The KRIS special library of spectra and emission probabilities in the decays of 1500 nuclei excited up to energies between 150 and 250 MeV was developed for correctly taking into account the decay of highly excited nuclei appearing as fission fragments. The emission of neutrons, protons, and photons was taken into account. Neutron emission fromprimary fragments was found to have a substantial effect on the formation of yields of postneutron nuclei. The library was tested by comparing the calculated and measured yields of products originating from the fission of nuclei that was induced by high-energy protons. The method for calculating these yields was tested on the basis of experimental data on the thermal-neutroninduced fission of {sup 235}U nuclei.

Grudzevich, O. T., E-mail: ogrudzevich@ippe.ru; Klinov, D. A. [Institute for Physics and Power Engineering (Russian Federation)] [Institute for Physics and Power Engineering (Russian Federation)

2013-07-15T23:59:59.000Z

240

Comparison of Fission Product Yields and Their Impact  

SciTech Connect (OSTI)

This memorandum describes the Naval Reactors Prime Contractor Team (NRPCT) Space Nuclear Power Program (SNPP) interest in determining the expected fission product yields from a Prometheus-type reactor and assessing the impact of these species on materials found in the fuel element and balance of plant. Theoretical yield calculations using ORIGEN-S and RACER computer models are included in graphical and tabular form in Attachment, with focus on the desired fast neutron spectrum data. The known fission product interaction concerns are the corrosive attack of iron- and nickel-based alloys by volatile fission products, such as cesium, tellurium, and iodine, and the radiological transmutation of krypton-85 in the coolant to rubidium-85, a potentially corrosive agent to the coolant system metal piping.

S. Harrison

2006-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Development of fission gas swelling and release models for metallic nuclear fuels  

E-Print Network [OSTI]

Fuel swelling and fission gas generation for fast reactor fuels are of high importance since they are among the main limiting factors in the development of metallic fast reactor fuel. Five new fission gas and swelling ...

Andrews, Nathan Christopher

2012-01-01T23:59:59.000Z

242

Comparison of various parametrizations of the double-humped fission barrier  

SciTech Connect (OSTI)

The double-humped potential barriers in actinide nuclei in the fission direction have been parametrized using three different procedures, namely, the smoothly joined parabolic segments, third-degree polynomials passing through and with zero slopes at the successive extremum points, and straight-line segments connecting the successive extremum points. The fission penetrabilities through the barriers and the ground-state spontaneous fission half-lives for a wide variety of 25 actinide nuclides have been calculated for these different parametrizations. Our results clearly indicate that while the third-degree polynomial and the straight-line parametrizations of the double-humped fission barrier lead to approximately similar results on the fission penetrability and fission half-lives, the corresponding results using the smoothly joined parabolic segment parametrization differ significantly by almost two to five orders of magnitude depending on the specific type of the fissioning nucleus and on the parameters of its corresponding double-humped fission barrier.

Bhandari, B.S.; Khaliquzzaman, M. (Physics Department, Faculty of Science, University of Garyounis, Benghazi, Libya (LY))

1991-07-01T23:59:59.000Z

243

E-Print Network 3.0 - actinide nuclei fission Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

fission with a large mass asymmetry within the self-consistent HFB theory. A new fis- sion valley... of this fission mode corresponds to the expected one in cluster...

244

E-Print Network 3.0 - asymmetric fission barriers Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

POLONICA B No 4 BIMODAL FISSION Summary: modes allows to describe observed asymmetric fis- sion of 256 Fm, as well as bimodal fission of 258 Fm... - particle states for the...

245

E-Print Network 3.0 - actinides fission products Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

fission with a large mass asymmetry within the self-consistent HFB theory. A new fis- sion valley... of this fission mode corresponds to the expected one in cluster...

246

A Time Projection Chamber for High Accuracy and Precision Fission Cross-Section Measurements  

SciTech Connect (OSTI)

The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4p acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

T. Hill; K. Jewell; M. Heffner; D. Carter; M. Cunningham; V. Riot; J. Ruz; S. Sangiorgio; B. Seilhan; L. Snyder; D. M. Asner; S. Stave; G. Tatishvili; L. Wood; R. G. Baker; J. L. Klay; R. Kudo; S. Barrett; J. King; M. Leonard; W. Loveland; L. Yao; C. Brune; S. Grimes; N. Kornilov; T. N. Massey; J. Bundgaard; D. L. Duke; U. Greife; U. Hager; E. Burgett; J. Deaven; V. Kleinrath; C. McGrath; B. Wendt; N. Hertel; D. Isenhower; N. Pickle; H. Qu; S. Sharma; R. T. Thornton; D. Tovwell; R. S. Towell; S.

2014-09-01T23:59:59.000Z

247

Cross section for {sup 246}Cm subbarrier fission  

SciTech Connect (OSTI)

The cross section for {sup 246}Cm fission induced by neutrons of energy in the range 0.1 eV-20 keV was measured by the neutron lead slowing-down spectrometer (LSDS-100) of the Institute for Nuclear Research (INR, Russian Academy of Sciences, Moscow). The parameters of the resonance area and of the fission width were evaluated for several low-lying s-wave neutron resonances. The parameters of the intermediate structure in the cross section for the subbarrier fusion of {sup 246}Cm nuclei were found. The results obtained in this way were compared with available experimental data and with recommended evaluated data.

Alekseev, A. A.; Bergman, A. A.; Berlev, A. I.; Koptelov, E. A. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation); Samylin, B. F.; Trufanov, A. M.; Fursov, B. I.; Shorin, V. S., E-mail: shorin@ippe.r [Institute for Physics and Power Engineering (Russian Federation)

2010-10-15T23:59:59.000Z

248

Fission product release from irradiated LWR fuel under accident conditions  

SciTech Connect (OSTI)

Fission product release from irradiated LWR fuel is being studied by heating fuel rod segments in flowing steam and an inert carrier gas to simulate accident conditions. Fuels with a range of irradiation histories are being subjected to several steam flow rates over a wide range of temperatures. Fission product release during each test is measured by gamma spectroscopy and by detailed examination of the collection apparatus after the test has been completed. These release results are complemented by a detailed posttest examination of samples of the fuel rod segment. Results of release measurements and fuel rod characterizations for tests at 1400 through 2000/sup 0/C are presented in this paper.

Strain, R.V.; Sanecki, J.E.; Osborne, M.F.

1984-01-01T23:59:59.000Z

249

Evidence for Conical Intersection Dynamics Mediating Ultrafast Singlet Exciton Fission  

E-Print Network [OSTI]

-Queisser limit for single-junction solar cells. By converting high-energy photons into two low-energy excited states, singlet fission offers a means to overcome thermalisation losses. Devices based on pentacene, a fission sensitiser, have demonstrated external... ), which aligns with the ground-state bleach (GSB) peaks in the middle of the spectrum. b Early-time dynamics from panel a. The initial stimulated emission at 700 nm decays to yield triplets with excited state absorption bands at 520 nm and 820 nm, which...

Musser, Andrew J.; Liebel, Matz; Schnedermann, Christoph; Wende, Torsten; Kehoe, Tom B.; Rao, Akshay; Kukura, Philipp

2015-01-01T23:59:59.000Z

250

Singlet fission efficiency in tetracene-based organic solar cells  

SciTech Connect (OSTI)

Singlet exciton fission splits one singlet exciton into two triplet excitons. Using a joint analysis of photocurrent and fluorescence modulation under a magnetic field, we determine that the triplet yield within optimized tetracene organic photovoltaic devices is 153%?±?5% for a tetracene film thickness of 20?nm. The corresponding internal quantum efficiency is 127%?±?18%. These results are used to prove the effectiveness of a simplified triplet yield measurement that relies only on the magnetic field modulation of fluorescence. Despite its relatively slow rate of singlet fission, the measured triplet yields confirm that tetracene is presently the best candidate for use with silicon solar cells.

Wu, Tony C., E-mail: tonyw@mit.edu; Thompson, Nicholas J.; Congreve, Daniel N.; Hontz, Eric; Yost, Shane R.; Van Voorhis, Troy; Baldo, Marc A., E-mail: baldo@mit.edu [Energy Frontier Research Center for Excitonics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2014-05-12T23:59:59.000Z

251

Direct Energy Conversion Fission Reactor for the period December 1, 1999 through February 29, 2000  

SciTech Connect (OSTI)

OAK B135 Direct Energy Conversion Fission Reactor for the period December 1, 1999 through February 29, 2000

Brown, L.C.

2000-03-20T23:59:59.000Z

252

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JUNE 1, 2001 THROUGH SEPTEMBER 30, 2001  

SciTech Connect (OSTI)

OAK-B135 DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JUNE 1, 2001 THROUGH SEPTEMBER 30, 2001

L.C. BROWN

2001-09-30T23:59:59.000Z

253

Recent progress in the study of fission barriers in covariant density functional theory  

E-Print Network [OSTI]

Recent progress in the study of fission barriers of actinides and superheavy nuclei within covariant density functional theory is overviewed.

A. V. Afanasjev; H. Abusara; P. Ring

2012-05-10T23:59:59.000Z

254

Methods to Collect, Compile, and Analyze Observed Short-lived Fission Product Gamma Data  

SciTech Connect (OSTI)

A unique set of fission product gamma spectra was collected at short times (4 minutes to 1 week) on various fissionable materials. Gamma spectra were collected from the neutron-induced fission of uranium, neptunium, and plutonium isotopes at thermal, epithermal, fission spectrum, and 14-MeV neutron energies. This report describes the experimental methods used to produce and collect the gamma data, defines the experimental parameters for each method, and demonstrates the consistency of the measurements.

Finn, Erin C.; Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.; Ellis, Tere A.

2011-09-29T23:59:59.000Z

255

E-Print Network 3.0 - advanced fission reactors Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

fission reactors, which release energy by splitting atoms... ) International Thermonuclear Experimental Reactor (ITER), which will be ... Source: Fusiongnition Research...

256

Nucleon-induced fission cross-sections of tantalum and separated tungsten isotopes and "compound nucleus" effect in intermediate energy region  

E-Print Network [OSTI]

Neutron- and proton-induced fission cross-sections of separated isotopes of tungsten (182W, 183W, 184W, and 186W) and 181Ta relative to 209Bi have been measured in the incident nucleon energy region 50 - 200 MeV using fission chambers based on thin-film breakdown counters (TFBC) using quasi-monoenergetic neutrons from the 7Li(p,n) reaction and at the proton beams of The Svedberg Laboratory (TSL), Uppsala University (Uppsala, Sweden). The results are compared with predictions by the CEM03.01 event generator, as well as with the recent data for nuclei in the lead-bismuth region. The effect of "compound nucleus" in the intermediate energy region is discussed, displaying in exponential dependence of nucleon-induced fission cross-sections on the parameter Z^2/A of the composite system (projectile+target nucleus), and in other characteristics of the fission process for which parameter Z^2/A plays a role similar to the one of the usual liquid-drop parameter Z^2/A of compound nuclei.

A. N. Smirnov; O. I. Batenkov; V. P. Eismont; N. P. Filatov; J. Blomgren; H. Conde; A. V. Prokofiev; S. G. Mashnik

2007-05-21T23:59:59.000Z

257

Quantum mechanical method of fragment's angular and energy distribution calculation for binary and ternary fission  

SciTech Connect (OSTI)

In the framework of quantum-mechanical fission theory, the method of calculation for partial fission width amplitudes and asymptotic behavior of the fissile nucleus wave function with strong channel coupling taken into account has been suggested. The method allows one to solve the calculation problem of angular and energy distribution countation for binary and ternary fission.

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Titova, L. V.; Pen'kov, N. V. [Voronezh State University (Russian Federation)

2006-08-15T23:59:59.000Z

258

INT Program INT13-3 Quantitative Large Amplitude Shape Dynamics: fission and heavy ion fusion  

E-Print Network [OSTI]

INT Program INT13-3 Quantitative Large Amplitude Shape Dynamics: fission and heavy ion fusion Talou, LANL "Fundamental and Applied Nuclear Fission Research at LANL" · 11:00 am: Anatoli Afanasjev, Mississippi State Univ "Fission in covariant DFT: status and open questions" Wednesday, October 2, 2013 Room C

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

259

NEANDC specialists meeting on yields and decay data of fission product nuclides  

SciTech Connect (OSTI)

Separate abstracts were prepared for the 29 papers presented. Workshop reports on decay heat, fission yields, beta- and gamma-ray spectroscopy, and delayed neutrons are included. An appendix contains a survey of the most recent compilations and evaluations containing fission product yield, fission product decay data, and delayed neutron yield information. (WHK)

Chrien, R.E.; Burrows, T.W. (eds.)

1983-01-01T23:59:59.000Z

260

NNSA TRITIUM SUPPLY CHAIN  

SciTech Connect (OSTI)

Savannah River Site plays a critical role in the Tritium Production Supply Chain for the National Nuclear Security Administration (NNSA). The entire process includes: • Production of Tritium Producing Burnable Absorber Rods (TPBARs) at the Westinghouse WesDyne Nuclear Fuels Plant in Columbia, South Carolina • Production of unobligated Low Enriched Uranium (LEU) at the United States Enrichment Corporation (USEC) in Portsmouth, Ohio • Irradiation of TPBARs with the LEU at the Tennessee Valley Authority (TVA) Watts Bar Reactor • Extraction of tritium from the irradiated TPBARs at the Tritium Extraction Facility (TEF) at Savannah River Site • Processing the tritium at the Savannah River Site, which includes removal of nonhydrogen species and separation of the hydrogen isotopes of protium, deuterium and tritium.

Wyrick, Steven [Savannah River National Laboratory, Aiken, SC, USA; Cordaro, Joseph [Savannah River National Laboratory, Aiken, SC, USA; Founds, Nanette [National Nuclear Security Administration, Albuquerque, NM, USA; Chambellan, Curtis [National Nuclear Security Administration, Albuquerque, NM, USA

2013-08-21T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Industry Supply Chain Development (Ohio)  

Broader source: Energy.gov [DOE]

Supply Chain Development programs are focused on targeted industries that have significant growth opportunities for Ohio's existing manufacturing sector from emerging energy resources and...

262

SOURCES 4C : a code for calculating ([alpha],n), spontaneous fission, and delayed neutron sources and spectra.  

SciTech Connect (OSTI)

SOURCES 4C is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to radionuclide decay. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., an intimate mixture of a-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 44 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 107 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code provides the magnitude and spectra, if desired, of the resultant neutron source in addition to an analysis of the'contributions by each nuclide in the problem. LASTCALL, a graphical user interface, is included in the code package.

Wilson, W. B. (William B.); Perry, R. T. (Robert T.); Shores, E. F. (Erik F.); Charlton, W. S. (William S.); Parish, Theodore A.; Estes, G. P. (Guy P.); Brown, T. H. (Thomas H.); Arthur, Edward D. (Edward Dana),; Bozoian, Michael; England, T. R.; Madland, D. G.; Stewart, J. E. (James E.)

2002-01-01T23:59:59.000Z

263

SOURCES 4A: A Code for Calculating (alpha,n), Spontaneous Fission, and Delayed Neutron Sources and Spectra  

SciTech Connect (OSTI)

SOURCES 4A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem.

Madland, D.G.; Arthur, E.D.; Estes, G.P.; Stewart, J.E.; Bozoian, M.; Perry, R.T.; Parish, T.A.; Brown, T.H.; England, T.R.; Wilson, W.B.; Charlton, W.S.

1999-09-01T23:59:59.000Z

264

The translational landscape of fission yeast meiosis and sporulation  

E-Print Network [OSTI]

of multiple regulatory layers shapes gene expression in fission yeast. Mol Cell 26, 145-55 (2007). 24. Matia-Gonzalez, A.M., Hasan, A., Moe, G.H., Mata, J. & Rodriguez-Gabriel, M.A. Functional characterization of Upf1 targets in Schizosaccharomyces pombe...

Duncan, Caia D. S.; Mata, Juan

2014-06-15T23:59:59.000Z

265

High Efficiency Organic Multilayer Photodetectors based on Singlet Fission ....................................................................................................................................................................................  

E-Print Network [OSTI]

.........................................................................................................................PH.14 High-efficiency, Low-cost Photovoltaics using III-V on Silicon Tandem CellsPhotonics High Efficiency Organic Multilayer Photodetectors based on Singlet Fission.........................................................................................................................PH.2 Efficiently Coupling Light to Superconducting Nanowire Single-photon Detectors

Reif, Rafael

266

Validation of MCNPX-PoliMi Fission Models  

SciTech Connect (OSTI)

We present new results on the measurement of correlated, outgoing neutrons from spontaneous fission events in a Cf-252 source. 16 EJ-309 liquid scintillation detectors are used to measure neutron-neutron correlations for various detector angles. Anisotropy in neutron emission is observed. The results are compared to MCNPX-PoliMi simulations and good agreement is observed.

S. A. Pozzi; S. D. Clarke; W. Walsh; E. C. Miller; J. Dolan; M. Flaska; B. M. Wieger; A. Enqvist; E. Padovani; J. K. Mattingly; D. L. Chichester; P. Peerani

2012-10-01T23:59:59.000Z

267

Characteristics of the samples in the FNG fission deposit collection  

SciTech Connect (OSTI)

Information concerning the samples in the Fast Neutron Generator (FNG) Group's fission deposit collection has been assembled. This includes the physical dimensions, isotopic analyses, half-lives, alpha emission rates specific activities and deposit weights. 10 refs., 9 figs., 5 tabs.

Meadows, J.W.

1990-12-01T23:59:59.000Z

268

Phase 1 Space Fission Propulsion Energy Source Design  

SciTech Connect (OSTI)

Fission technology can enable rapid, affordable access to any point in the solar system. If fission propulsion systems are to be developed to their full potential; however, near-term customers must be identified and initial fission systems successfully developed, launched, and operated. Studies conducted in fiscal year 2001 (IISTP, 2001) show that fission electric propulsion (FEP) systems with a specific mass at or below 50 kg/kWjet could enhance or enable numerous robotic outer solar system missions of interest. At the required specific mass, it is possible to develop safe, affordable systems that meet mission requirements. To help select the system design to pursue, eight evaluation criteria were identified: system integration, safety, reliability, testability, specific mass, cost, schedule, and programmatic risk. A top-level comparison of four potential concepts was performed: a Testable, Passive, Redundant Reactor (TPRR), a Testable Multi-Cell In-Core Thermionic Reactor (TMCT), a Direct Gas Cooled Reactor (DGCR), and a Pumped Liquid Metal Reactor (PLMR). Development of any of the four systems appears feasible. However, for power levels up to at least 500 kWt (enabling electric power levels of 125-175 kWe, given 25-35% power conversion efficiency) the TPRR has advantages related to several criteria and is competitive with respect to all. Hardware-based research and development has further increased confidence in the TPRR approach. Successful development and utilization of a 'Phase 1' fission electric propulsion system will enable advanced Phase 2 and Phase 3 systems capable of providing rapid, affordable access to any point in the solar system. (authors)

Houts, Mike; Van Dyke, Melissa; Godfroy, Tom; Pedersen, Kevin; Martin, James; Dickens, Ricky; Salvail, Pat; Hrbud, Ivana; Carter, Robert [NASA MSFC, TD40, Marshall Space Flight Center, Alabama, 35812 (United States)

2002-07-01T23:59:59.000Z

269

The DART dispersion analysis research tool: A mechanistic model for predicting fission-product-induced swelling of aluminum dispersion fuels. User`s guide for mainframe, workstation, and personal computer applications  

SciTech Connect (OSTI)

This report describes the primary physical models that form the basis of the DART mechanistic computer model for calculating fission-product-induced swelling of aluminum dispersion fuels; the calculated results are compared with test data. In addition, DART calculates irradiation-induced changes in the thermal conductivity of the dispersion fuel, as well as fuel restructuring due to aluminum fuel reaction, amorphization, and recrystallization. Input instructions for execution on mainframe, workstation, and personal computers are provided, as is a description of DART output. The theory of fission gas behavior and its effect on fuel swelling is discussed. The behavior of these fission products in both crystalline and amorphous fuel and in the presence of irradiation-induced recrystallization and crystalline-to-amorphous-phase change phenomena is presented, as are models for these irradiation-induced processes.

Rest, J.

1995-08-01T23:59:59.000Z

270

Molten salt extraction of transuranic and reactive fission products from used uranium oxide fuel  

DOE Patents [OSTI]

Used uranium oxide fuel is detoxified by extracting transuranic and reactive fission products into molten salt. By contacting declad and crushed used uranium oxide fuel with a molten halide salt containing a minor fraction of the respective uranium trihalide, transuranic and reactive fission products partition from the fuel to the molten salt phase, while uranium oxide and non-reactive, or noble metal, fission products remain in an insoluble solid phase. The salt is then separated from the fuel via draining and distillation. By this method, the bulk of the decay heat, fission poisoning capacity, and radiotoxicity are removed from the used fuel. The remaining radioactivity from the noble metal fission products in the detoxified fuel is primarily limited to soft beta emitters. The extracted transuranic and reactive fission products are amenable to existing technologies for group uranium/transuranic product recovery and fission product immobilization in engineered waste forms.

Herrmann, Steven Douglas

2014-05-27T23:59:59.000Z

271

arXiv:nucl-th/0607015v213Jul2006 Direct reactions in/for astrophysics  

E-Print Network [OSTI]

. In recent years direct reactions methods have been developed and applied to extract low-energy astrophysical are focused on the opposite ends of the energy scale of nuclear reactions: (a) the very high and (b) the very end of the energy scale are the low energy reactions of importance for stellar evolution. Chains

Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

272

Theoretical Studies on the CH3CO + Cl Reaction: Hydrogen Abstraction versus CO Displacement  

E-Print Network [OSTI]

potential energy surface reveals this reaction to be a capture-limited association-elimination reaction the efficiency of a chain reaction. Recently Maricq et al.1 reported the real-time kinetic mea- surements for one earlier potential energy surface,3 is also consistent with an addition-elimination mechanism since

Nguyen, Minh Tho

273

Methyl viologen radical reactions with several oxidizing agents. [Gamma Radiation  

SciTech Connect (OSTI)

The rates of oxidation of the methyl viologen radical by peroxodisulfate and hydrogen peroxide has been investigated. The methyl viologen free radical was produced by pulse radiolysis. The reaction of the peroxodisulfate radical with the methyl viologen radical was first order in both species, and the reaction rate constant is reported. A el-radiation study revealed a chain decomposition of the peroxodisulfate radical involving the methyl viologen radical when methanol, ethanol, or 2-propanol was present. Loss of the methyl viologen radical was then no longer observed to be a simple first-order reaction. The reaction of hydrogen peroxide with the methyl viologen radical was very slow in the presence of 1 M methanol. A much faster reaction in the absence of methanol was interpreted to be a reaction of the methyl viologen radical with the peroxy radicals. Hydrogen peroxide, in contrast to the chain decomposition of peroxodisulfate radicals, does not participate in a chain reaction involving the methyl viologen radical and methanol. Rate constants for the reaction of methyl viologen radical with dichromate radical, iodate radical, and ferricyanide radical are reported.

Levey, G.; Ebbesen, T.W.

1983-01-01T23:59:59.000Z

274

Report to the DOE nuclear data committee. [EV RANGE 10-100; CROSS SECTIONS; PHOTONEUTRONS; NEUTRONS; GAMMA RADIATION; COUPLED CHANNEL THEORY; DIFFERENTIAL CROSS SECTIONS; MEV RANGE 01-10; ; CAPTURE; GAMMA SPECTRA; THERMAL NEUTRONS; COMPUTER CALCULATIONS; DECAY; FISSION PRODUCTS; FISSION YIELD; SHELL MODELS; NUCLEAR DATA COLLECTIONS  

SciTech Connect (OSTI)

Topics covered include: studies of (n, charged particle) reactions with 14 to 15 MeV neutrons; photoneutron cross sections for /sup 15/N; neutron radiative capture; Lane-model analysis of (p,p) and (n,n) scattering on the even tin isotopes; neutron scattering cross sections for /sup 181/Ta, /sup 197/Au, /sup 209/Bi, /sup 232/Th, and /sup 238/U inferred from proton scattering and charge exchange cross sections; neutron-induced fission cross sections of /sup 245/Cm and /sup 242/Am; fission neutron multiplicities for /sup 245/Cm and /sup 242/Am; the transport of 14 MeV neutrons through heavy materials 150 < A < 208; /sup 249/Cm energy levels from measurement of thermal neutron capture gamma rays; /sup 231/Th energy levels from neutron capture gamma ray and conversion electron spectroscopy; new measurements of conversion electron binding energies in berkelium and californium; nuclear level densities; relative importance of statistical vs. valence neutron capture in the mass-90 region; determination of properties of short-lived fission products; fission yield of /sup 87/Br and /sup 137/I from 15 nuclei ranging from /sup 232/Th to /sup 249/Cf; evaluation of charged particle data for the ECPL library; evaluation of secondary charged-particle energy and angular distributions for ENDL; and evaluated nuclear structure libraries derived from the table of isotopes. (GHT)

Struble, G.L.; Haight, R.C.

1981-03-01T23:59:59.000Z

275

Measurements of Nucleon-Induced Fission Cross-Sections of Separated Tungsten Isotopes and Natural Tungsten in the 50-200 MeV Energy Region  

E-Print Network [OSTI]

Neutron- and proton-induced fission cross-sections of separated isotopes of tungsten (182W, 183W, 184W, and 186W) and natural tungsten relative to 209Bi have been measured in the incident nucleon energy region 50-200 MeV using fission chambers based on thin-film breakdown counters (TFBC) at quasi-monoenergetic neutrons from the 7Li(p,n) reaction and at the proton beams of The Svedberg Laboratory (TSL), Uppsala University (Uppsala, Sweden). The preliminary experimental data are presented in comparison with the recent data for nuclei in the lead-bismuth region, as well as with predictions by the CEM03.01 event generator.

V. P. Eismont; N. P. Filatov; A. N. Smirnov; S. M. Soloviev; J. Blomgren; H. Conde; A. V. Prokofiev; S. G. Mashnik

2005-07-07T23:59:59.000Z

276

Fusion-Fission Hybrid for Fissile Fuel Production without Processing  

SciTech Connect (OSTI)

Two scenarios are typically envisioned for thorium fuel cycles: 'open' cycles based on irradiation of {sup 232}Th and fission of {sup 233}U in situ without reprocessing or 'closed' cycles based on irradiation of {sup 232}Th followed by reprocessing, and recycling of {sup 233}U either in situ or in critical fission reactors. This study evaluates a third option based on the possibility of breeding fissile material in a fusion-fission hybrid reactor and burning the same fuel in a critical reactor without any reprocessing or reconditioning. This fuel cycle requires the hybrid and the critical reactor to use the same fuel form. TRISO particles embedded in carbon pebbles were selected as the preferred form of fuel and an inertial laser fusion system featuring a subcritical blanket was combined with critical pebble bed reactors, either gas-cooled or liquid-salt-cooled. The hybrid reactor was modeled based on the earlier, hybrid version of the LLNL Laser Inertial Fusion Energy (LIFE1) system, whereas the critical reactors were modeled according to the Pebble Bed Modular Reactor (PBMR) and the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) design. An extensive neutronic analysis was carried out for both the hybrid and the fission reactors in order to track the fuel composition at each stage of the fuel cycle and ultimately determine the plant support ratio, which has been defined as the ratio between the thermal power generated in fission reactors and the fusion power required to breed the fissile fuel burnt in these fission reactors. It was found that the maximum attainable plant support ratio for a thorium fuel cycle that employs neither enrichment nor reprocessing is about 2. This requires tuning the neutron energy towards high energy for breeding and towards thermal energy for burning. A high fuel loading in the pebbles allows a faster spectrum in the hybrid blanket; mixing dummy carbon pebbles with fuel pebbles enables a softer spectrum in the critical reactors. This combination consumes about 20% of the thorium initially loaded in the hybrid reactor ({approx}200 GWd/tHM), partially during hybrid operation, but mostly during operation in the critical reactor. The plant support ratio is low compared to the one attainable using continuous fuel chemical reprocessing, which can yield a plant support ratio of about 20, but the resulting fuel cycle offers better proliferation resistance as fissile material is never separated from the other fuel components.

Fratoni, M; Moir, R W; Kramer, K J; Latkowski, J F; Meier, W R; Powers, J J

2012-01-02T23:59:59.000Z

277

Improve supply chain resilience by multi-stage supply chain  

E-Print Network [OSTI]

Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...

Xu, Jie, M. Eng. Massachusetts Institute of Technology

2009-01-01T23:59:59.000Z

278

Improving supply chain resilience by multi-stage supply chain  

E-Print Network [OSTI]

Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...

Yang, Jingxia, M. Eng, Massachusetts Institute of Technology

2009-01-01T23:59:59.000Z

279

Ph.D. Theses 1. M. Dasgupta Study of cross section and average angular momenta in fusion reactions of 28  

E-Print Network [OSTI]

(TIFR, 1992) 2. Pragya Singh Spectroscopy of high spin nuclear states of 92,91,90 Mo excited by heavy to transient magnetic fields (1993) 5. M.K. Sharan Study of high energy gamma rays following heavy ion-fission reactions (BARC, 1994) 7. S. Chattopadhyay Investigation of nuclear structure at high spins in mass-80

Shyamasundar, R.K.

280

On Thermonuclear Reaction Rates  

E-Print Network [OSTI]

Nuclear reactions govern major aspects of the chemical evolution od galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction probability integrals for nuclear reactions in the case of nonresonant, modified nonresonant, screened nonresonant and resonant cases are given. These are expressed in terms of H-functions, G-functions and in computable series forms. Computational aspects are also discussed.

H. J. Haubold; A. M. Mathai

1996-12-02T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Delayed neutron data and group parameters for 43 fissioning systems  

SciTech Connect (OSTI)

The quality and quantity of delayed neutron precursor data have greatly improved over the past decade and a half. Supplementation of the data with model calculations and the use of models to extend the number of precursors to 271 is now practical. These data, along with other improved fission product parameters, permit direct calculations of aggregate behavior for many fissioning nuclides. The results can still be approximated using a few (usually six) temporal groups, including corresponding spectra, as in past practice for reactor physics. An extensive effort to provide a complete set of evaluated data is summarized, with an emphasis on its use to generate the temporal approximations; precursor data and group values are intended for inclusion in ENDF/B-VI.

Brady, M.C. (Oak Ridge National Lab., TN (USA)); England, T.R. (Los Alamos National Lab., NM (USA))

1989-10-01T23:59:59.000Z

282

Method of fission heat flux determination from experimental data  

DOE Patents [OSTI]

A method is provided for determining the fission heat flux of a prime specimen inserted into a specimen of a test reactor. A pair of thermocouple test specimens are positioned at the same level in the holder and a determination is made of various experimental data including the temperature of the thermocouple test specimens, the temperature of bulk water channels located in the test holder, the gamma scan count ratios for the thermocouple test specimens and the prime specimen, and the thicknesses of the outer clads, the fuel fillers, and the backclad of the thermocouple test specimen. Using this experimental data, the absolute value of the fission heat flux for the thermocouple test specimens and prime specimen can be calculated.

Paxton, Frank A. (Schenectady, NY)

1999-01-01T23:59:59.000Z

283

Systematics of the deduced fission barriers for the doubly even transactinium nuclei  

SciTech Connect (OSTI)

The systematics of the fission barrier shapes of a total of 47 doubly even actinide and transactinide nuclei have been studied using the double-humped fission barrier model. The fission barrier has been parametrized in terms of four smoothly joined parabolic segments. The penetrabilities through such double-humped fission barriers have been calculated in the Wentzel-Kramers-Brillouin approximation, and the various fission half-lives have been determined using the formalism given earlier by Nix and Walker. The various parameters of such fission barriers have been deduced by requiring their simultaneous consistency with the various relevant fission observables, namely, the near-barrier fission cross sections, isomeric energies and isomeric half-lives, where available, and the ground-state spontaneous fission half-lives in the region 90{le}{ital Z}{le}98, and such model calculations with some further justifiable asssumptions have been extended to the region of the still heavier nuclei with {ital Z}{ge}100. The results of our systematic study of the heights of the inner and the outer barriers of the double-humped fission barriers corresponding to such doubly even nuclei suggest that while the height of the inner barrier remains approximately constant in the entire region of such nuclei, the deduced heights of the outer barrier decrease rather sharply and continuously with the increase in the value of the fissility parameter until one reaches the element Rf ({ital Z}=104).

Bhandari, B.S.; Bendardaf, Y.B. (Department of Physics, Faculty of Science, University of Garyounis, Benghazi (Libya))

1992-06-01T23:59:59.000Z

284

Effective contracts in supply chains  

E-Print Network [OSTI]

In the past decade, we have seen significant increase in the level of outsourcing in many industries. This increase in the level of outsourcing increases the importance of implementing effective contracts in supply chains. ...

Shum, Wanhang

2007-01-01T23:59:59.000Z

285

Total supply chain cost model  

E-Print Network [OSTI]

Sourcing and outsourcing decisions have taken on increased importance within Teradyne to improve efficiency and competitiveness. This project delivered a conceptual framework and a software tool to analyze supply chain ...

Wu, Claudia

2005-01-01T23:59:59.000Z

286

Extracorporeal membrane oxygenation promotes long chain fatty...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

membrane oxygenation promotes long chain fatty acid oxidation in the immature swine heart in vivo. Extracorporeal membrane oxygenation promotes long chain fatty acid oxidation...

287

Microscopic cold fission yields of {sup 252}Cf  

SciTech Connect (OSTI)

We show that the sharp maximum corresponding to {sup 107}Mo in the fragment distribution of the {sup 252}Cf cold fission is actually a Sn-like radioactivity, similar to other decay processes in which magic nuclei are involved, namely alpha decay and heavy cluster emission, also called Pb-like radioactivity. It turns out that the mass asymmetry degree of freedom has a key role in connecting initial Sn with the final Mo isotopes along the fission path. We investigate the cold rearrangement of nucleons within the framework of the two-center shell model in order to compute the cold valleys in the charge equilibrated fragmentation potential. The fission yields are estimated by using the semiclassical penetration approach. We consider 5 degrees of freedom, namely the interfragment distance, the shapes of fragments, the neck parameter, and mass asymmetry. We found an isomeric minimum between the internal and external barriers. It turns out that the inner cold valley of the total potential energy is connected to the doubly magic isotope {sup 132}Sn.

Mirea, M. [National Institute of Physics and Nuclear Engineering, 407 Atomistilor, RO-077125 Bucharest-Magurele (Romania); Delion, D. S. [National Institute of Physics and Nuclear Engineering, 407 Atomistilor, RO-077125 Bucharest-Magurele (Romania); Academy of Romanian Scientists 54 Splaiul Independentei, RO-050094 Bucharest (Romania); Sandulescu, A. [Academy of Romanian Scientists 54 Splaiul Independentei, RO-050094 Bucharest (Romania); Institute for Advanced Studies in Physics, 129 Calea Victoriei, Bucharest (Romania)

2010-04-15T23:59:59.000Z

288

(Fission product transport experiments (HFR-B1))  

SciTech Connect (OSTI)

Travel to the JRC Petten was for the purpose of discussing the HFR-B1 experiment and post irradiation activities. Technical assessment of the experiment strongly supports the concept of enhanced fission gas release at temperatures above 1100{degree}C, the extensive release of stored fission gas at water vapor levels postulated in accident scenarios, an increase in the steady-state fission gas release under hydrolyzing conditions, and an increase in gas release during thermal cycling. Schedules were established for completion of the work and issuance of reports by September 1990. At the KFA Juelich agreement was reached on the PIE activities for HFR-B1 and a schedule established. The final PIE report is due June 1991. Choices of accident condition tests in the PIE have yet to be made by the US participants. A proposal for the establishment of a new cooperative effort on model and code development was presented at the Institut fuer Nukleare Sicherheitsforschung of KFA. The proposal was considered premature; discussions dealing with general principles, basic aims, and organization were requested; particular concerns about free exchange of information, overlap with the existing safety subprogram, and exclusive cooperation with ORNL were raised. A strong desire for cooperation and the opinion that the raised problems could be resolved were expressed. Technical discussions at the KFA were beneficial.

Myers, B.F.

1989-12-05T23:59:59.000Z

289

Direct fission fragment energy converter - Magnetic collimator option  

SciTech Connect (OSTI)

The present study was focused on developing a technologically feasible power system that is based on direct fission fragment energy conversion utilizing magnetic collimation. The new concept is an attempt to combine several advantageous design solutions, which have been proposed for application in both fission and fusion reactors, into one innovative system that can offer exceptional energy conversion efficiency. The analysis takes into consideration a wide range of operational aspects including fission fragment escape from the fuel, collimation, collection, criticality, long-term performance, energy conversion efficiency, heat removal, and safety characteristics. Specific characteristics of the individual system components and the entire system are evaluated. Analysis and evaluation of the technological feasibility of the concept were achieved using state-of-the-art computer codes that allowed realistic and consistent modeling. In addition to the extensive computational effort, the scaled prototype experimental proof-of-principle program was conducted to validate basic physics of the concept. The program was focused on electromagnetic components and experimental demonstration of performance. This paper summarizes the final results of the 6-years research program including both computational and experimental efforts. Potential future research and development and anticipated applications are discussed. (authors)

Tsvetkov, P. V.; Hart, R. R. [Dept. of Nuclear Engineering, Texas AandM Univ., 129 Zachry Engineering Center, College Station, TX 77843-3133 (United States)

2006-07-01T23:59:59.000Z

290

Uncertainties analysis of fission fraction for reactor antineutrino experiments using DRAGON  

E-Print Network [OSTI]

Rising interest in nuclear reactors as a source of antineutrinos for experiments motivates validated, fast, and accessible simulation to predict reactor rates. First, DRAGON was developed to calculate the fission rates of the four most important isotopes in fissions,235U,238U,239Pu and141Pu, and it was validated for PWRs using the Takahama benchmark. The fission fraction calculation function was validated through comparing our calculation results with MIT's results. we calculate the fission fraction of the Daya Bay reactor core, and compare its with those calculated by the commercial reactor simulation program SCIENCE, which is used by the Daya Bay nuclear power plant, and the results was consist with each other. The uncertainty of the antineutrino flux by the fission fraction was studied, and the uncertainty of the antineutrino flux by the fission fraction simulation is 0.6% per core for Daya Bay antineutrino experiment.

X. B. Ma; L. Z. Wang; Y. X. Chen; W. L. Zhong; F. P. An

2014-05-27T23:59:59.000Z

291

Experimental Measurements of Short-Lived Fission Products from Uranium, Neptunium, Plutonium and Americium  

SciTech Connect (OSTI)

Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on the short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on a HPGe (high purity germanium) detector to begin counting in less than 3 minutes post irradiation. The samples were counted for various time intervals ranging from 5 minutes to 1 hour. The data was then analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.

Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.

2009-11-01T23:59:59.000Z

292

Microstructural Characterization of Irradiated U-7Mo/Al-5Si Dispersion to High Fission Density  

SciTech Connect (OSTI)

The fuel development program for research and test reactors calls for improved knowledge on the effect of microstructure on fuel performance in reactors. This work summarizes the recent TEM microstructural characterization of an irradiated U-7Mo/Al-5Si dispersion fuel plate (R3R050) irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory to 5.2×1021 fissions/cm3. While a large fraction of the fuel grains is decorated with large bubbles, there is no evidence showing interlinking of these large bubbles at the specified fission density. The attachment of solid fission product precipitates to the bubbles is likely the result of fission product diffusion into these bubbles. The process of fission gas bubble superlattice collapse appears through bubble coalescence. The results are compared with the previous TEM work of the dispersion fuels irradiated to lower fission density from the same fuel plate.

J. Gan; B. D. Miller; D. D. Keiser, Jr.; A. B. Robinson; J. W. Madden; P. G. Medvedev; D. M. Wachs

2014-11-01T23:59:59.000Z

293

Experimental and theoretical studies of OH-initiated reactions of isoprene  

E-Print Network [OSTI]

and pathways. In each step of the chain reaction, organic radical intermediates are produced and they further propagate or terminate the oxidation process. Currently, there is very little understanding of the chemistry of these organic radicals. This study...

Zhang, Dan

2012-06-07T23:59:59.000Z

294

Measurements of prompt gamma-rays from fast-neutron induced fission with the LICORNE directional neutron source  

E-Print Network [OSTI]

At the IPN Orsay we have developed a unique, directional, fast neutron source called LICORNE, intended initially to facilitate prompt fission gamma measurements. The ability of the IPN Orsay tandem accelerator to produce intense beams of $^7$Li is exploited to produce quasi-monoenergetic neutrons between 0.5 - 4 MeV using the p($^7$Li,$^7$Be)n inverse reaction. The available fluxes of up to 7 × 10$^7$ neutrons/second/steradian for the thickest hydrogen-rich targets are comparable to similar installations, but with two added advantages: (i) The kinematic focusing produces a natural neutron beam collimation which allows placement of gamma detectors adjacent to the irradiated sample unimpeded by source neutrons. (ii) The background of scattered neutrons in the experimental hall is drastically reduced. The dedicated neutron converter was commissioned in June 2013. Some preliminary results from the first experiment using the LICORNE neutron source at the IPN Orsay are presented. Prompt fission gamma rays from fas...

Wilson, J N; Halipre, P; Oberstedt, S; Oberstedt, A

2014-01-01T23:59:59.000Z

295

CALCULATING THE CARBON FOOTPRINT SUPPLY CHAIN FOR  

E-Print Network [OSTI]

CALCULATING THE CARBON FOOTPRINT SUPPLY CHAIN FOR THE SEMICONDUCTOR INDUSTRY By: Yasser Dessouky #12;Carbon Footprint Supply Chain Carbon Trust defines carbon footprint of a supply chain as follows: "The carbon footprint of a product is the carbon dioxide emitted across the supply chain for a single

Su, Xiao

296

Measurements of cross sections and decay properties of the isotopes of elements 112, 114, and 116 produced in the fusion reactions {sup 233,238}U, {sup 242}Pu, and {sup 248}Cm+{sup 48}Ca  

SciTech Connect (OSTI)

We have studied the dependence of the production cross sections of the isotopes {sup 282,283}112 and {sup 286,287}114 on the excitation energy of the compound nuclei {sup 286}112 and {sup 290}114. The maximum cross section values of the xn-evaporation channels for the reaction {sup 238}U({sup 48}Ca,xn){sup 286-x}112 were measured to be {sigma}{sub 3n}=2.5{sub -1.1}{sup +1.8} pb and {sigma}{sub 4n}=0.6{sub -0.5}{sup +1.6} pb; for the reaction {sup 242}Pu({sup 48}Ca,xn){sup 290-x}114: {sigma}{sub 2n}{approx}0.5 pb, {sigma}{sub 3n}=3.6{sub -1.7}{sup +3.4} pb, and {sigma}{sub 4n}=4.5{sub -1.9}{sup +3.6} pb. In the reaction {sup 233}U({sup 48}Ca,2-4n){sup 277-279}112 at E*=34.9=2.2 MeV we measured an upper cross section limit of {sigma}{sub xn}{<=}0.6 pb. The observed shift of the excitation energy associated with the maximum sum evaporation residue cross section {sigma}{sub ER}(E*) to values significantly higher than that associated with the calculated Coulomb barrier can be caused by the orientation of the deformed target nucleus in the entrance channel of the reaction. An increase of {sigma}{sub ER} in the reactions of actinide targets with {sup 48}Ca is consistent with the expected increase of the survivability of the excited compound nucleus upon closer approach to the closed neutron shell N=184. In the present work we detected 33 decay chains arising in the decay of the known nuclei {sup 282}112, {sup 283}112, {sup 286}114, {sup 287}114, and {sup 288}114. In the decay of {sup 287}114({alpha}){yields}{sup 283}112({alpha}){yields}{sup 279}110(SF), in two cases out of 22, we observed decay chains of four and five sequential {alpha} transitions that end in spontaneous fission of {sup 271}Sg (T{sub {alpha}}{sub /SF}=2.4{sub -1.0}{sup +4.3} min) and {sup 267}Rf (T{sub SF}{approx}2.3 h), longer decay chains than reported previously. We observed the new nuclide {sup 292}116 (T{sub {alpha}}=18{sub -6}{sup +16} ms,E{sub {alpha}}=10.66{+-}0.07 MeV) in the irradiation of the {sup 248}Cm target at a higher energy than in previous experiments. The observed nuclear decay properties of the nuclides with Z=104-118 are compared with theoretical nuclear mass calculations and the systematic trends of spontaneous fission properties. As a whole, they give a consistent pattern of decay of the 18 even-Z neutron-rich nuclides with Z=104-118 and N=163-177. The experiments were performed with the heavy-ion beam delivered by the U400 cyclotron of the FLNR (JINR, Dubna) employing the Dubna gas-filled recoil separator.

Oganessian, Yu.Ts.; Utyonkov, V.K.; Lobanov, Yu.V.; Abdullin, F.Sh.; Polyakov, A.N.; Shirokovsky, I.V.; Tsyganov, Yu.S.; Gulbekian, G.G.; Bogomolov, S.L.; Gikal, B.N.; Mezentsev, A.N.; Iliev, S.; Subbotin, V.G.; Sukhov, A.M.; Voinov, A.A.; Buklanov, G.V.; Subotic, K.; Zagrebaev, V.I.; Itkis, M.G.; Patin, J.B. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States); Russian Federal Nuclear Center, All-Russian Research Institute of Experimental Physics, 607190 Sarov (Russian Federation)] [and others

2004-12-01T23:59:59.000Z

297

E-Print Network 3.0 - affordable fission engine Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

nearly doubled, from 528 million to 936 million... specific parts, one of which covers fusion, fission and radiation protection research, including... the International...

298

E-Print Network 3.0 - absolute thermal fission Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

- Department of Geology and Geophysics, Yale University; Garver, John I. - Department of Geology, Union College Collection: Geosciences 28 Nuclear fission time measurements as a...

299

E-Print Network 3.0 - alpha -particle fission Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

thermal history Summary: -feldspar ages (214 Ma) from the Jiazishan syenites. A titanite fission-track age of 166 8 Ma (closure... cooling and reheating event is indicated...

300

Event-by-event study of neutron observables in spontaneous and thermal fission  

SciTech Connect (OSTI)

The event-by-event fission model FREYA is extended to spontaneous fission of actinides and a variety of neutron observables are studied for spontaneous fission and fission induced by thermal neutrons with a view towards possible applications for SNM detection. We have shown that event-by-event models of fission, such as FREYA, provide a powerful tool for studying fission neutron correlations. Our results demonstrate that these correlations are significant and exhibit a dependence on the fissioning nucleus. Since our method is phenomenological in nature, good input data are especially important. Some of the measurements employed in FREYA are rather old and statistics limited. It would be useful to repeat some of these studies with modern detector techniques. In addition, most experiments made to date have not made simultaneous measurements of the fission products and the prompt observables, such as neutron and photons. Such data, while obviously more challenging to obtain, would be valuable for achieving a more complete understanding of the fission process.

Vogt, R; Randrup, J

2011-09-14T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Measurement of {sup 235}U content and flow of UF{sub 6} using delayed neutrons or gamma rays following induced fission  

SciTech Connect (OSTI)

Feasibility experiments conducted at Pacific Northwest National Laboratory demonstrate that either delayed neutrons or energetic gamma rays from short-lived fission products can be used to monitor the blending of UF{sub 6} gas streams. A {sup 252}Cf neutron source was used to induce {sup 235}U fission in a sample, and delayed neutrons and gamma rays were measured after the sample moved {open_quotes}down-stream.{close_quotes} The experiments used a UO{sub 2} powder that was transported down the pipe to simulate the flowing UF{sub 6} gas. Computer modeling and analytic calculation extended the test results to a flowing UF{sub 6} gas system. Neutron or gamma-ray measurements made at two downstream positions can be used to indicate both the {sup 235}U content and UF{sub 6} flow rate. Both the neutron and gamma-ray techniques have the benefits of simplicity and long-term reliability, combined with adequate sensitivity for low-intrusion monitoring of the blending process. Alternatively, measuring the neutron emission rate from (a, n) reactions in the UF{sub 6} provides an approximate measure of the {sup 235}U content without using a neutron source to induce fission.

Stromswold, D.C.; Peurrung, A.J.; Reeder, P.L.; Perkins, R.W.

1996-06-01T23:59:59.000Z

302

Fusion-Fission for Superheavy (Z{approx}110-126) and Super-Superheavy (Z{approx}160-180) Nuclear Systems  

SciTech Connect (OSTI)

Low-energy damped collisions of very heavy nuclei (238U+238U, 232Th+250Cf and 238U+248Cm) are investigated within a realistic model based on multi-dimensional Langevin equations. Large charge and mass transfer was found in these reactions due to the inverse (anti-symmetrizing) quasi-fission process leading to formation of survived superheavy long-lived neutron-rich nuclei. In many events the lifetime of the composite system consisting of two touching nuclei (giant quasi-atoms) turns out to be rather long; sufficient for spontaneous positron formation from super-strong electric field, a fundamental QED process.

Greiner, Walter [Frankfurt Institute for Advanced Studies, J.W. Goethe-Universitaet, Frankfurt (Germany); Zagrebaev, Valery [Flerov Laboratory of Nuclear Reaction, JINR, Dubna, 141980, Moscow region (Russian Federation)

2006-08-14T23:59:59.000Z

303

Differential evolution Markov chain with snooker updater and fewer chains  

SciTech Connect (OSTI)

Differential Evolution Markov Chain (DE-MC) is an adaptive MCMC algorithm, in which multiple chains are run in parallel. Standard DE-MC requires at least N=2d chains to be run in parallel, where d is the dimensionality of the posterior. This paper extends DE-MC with a snooker updater and shows by simulation and real examples that DE-MC can work for d up to 50--100 with fewer parallel chains (e.g. N=3) by exploiting information from their past by generating jumps from differences of pairs of past states. This approach extends the practical applicability of DE-MC and is shown to be about 5--26 times more efficient than the optimal Normal random walk Metropolis sampler for the 97.5% point of a variable from a 25--50 dimensional Student T{sub 3} distribution. In a nonlinear mixed effects model example the approach outperformed a block-updater geared to the specific features of the model.

Vrugt, Jasper A [Los Alamos National Laboratory; Ter Braak, Cajo J F [NON LANL

2008-01-01T23:59:59.000Z

304

Analysis of Fission Products on the AGR-1 Capsule Components  

SciTech Connect (OSTI)

The components of the AGR-1 irradiation capsules were analyzed to determine the retained inventory of fission products in order to determine the extent of in-pile fission product release from the fuel compacts. This includes analysis of (i) the metal capsule components, (ii) the graphite fuel holders, (iii) the graphite spacers, and (iv) the gas exit lines. The fission products most prevalent in the components were Ag-110m, Cs 134, Cs 137, Eu-154, and Sr 90, and the most common location was the metal capsule components and the graphite fuel holders. Gamma scanning of the graphite fuel holders was also performed to determine spatial distribution of Ag-110m and radiocesium. Silver was released from the fuel components in significant fractions. The total Ag-110m inventory found in the capsules ranged from 1.2×10 2 (Capsule 3) to 3.8×10 1 (Capsule 6). Ag-110m was not distributed evenly in the graphite fuel holders, but tended to concentrate at the axial ends of the graphite holders in Capsules 1 and 6 (located at the top and bottom of the test train) and near the axial center in Capsules 2, 3, and 5 (in the center of the test train). The Ag-110m further tended to be concentrated around fuel stacks 1 and 3, the two stacks facing the ATR reactor core and location of higher burnup, neutron fluence, and temperatures compared with Stack 2. Detailed correlation of silver release with fuel type and irradiation temperatures is problematic at the capsule level due to the large range of temperatures experienced by individual fuel compacts in each capsule. A comprehensive Ag 110m mass balance for the capsules was performed using measured inventories of individual compacts and the inventory on the capsule components. For most capsules, the mass balance was within 11% of the predicted inventory. The Ag-110m release from individual compacts often exhibited a very large range within a particular capsule.

Paul A. Demkowicz; Jason M. Harp; Philip L. Winston; Scott A. Ploger

2013-03-01T23:59:59.000Z

305

NEET Micro-Pocket Fission Detector -- FY 2012 Status Report  

SciTech Connect (OSTI)

A research program has been initiated by the NEET program for developing and testing compact miniature fission chambers capable of simultaneously measuring thermal neutron flux, fast neutron flux and temperature within a single package. When implemented, these sensors will significantly advance flux detection capabilities for irradiation tests in US Materials Test Reactors (MTRs).Ultimately, evaluations may lead to a more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, high performance reactors and commercial nuclear power plants. Deployment of Micro-Pocket Fission Detectors (MPFDs) in US DOE-NE program irradiation tests will address several challenges: Current fission chamber technologies do not offer the ability to measure fast flux, thermal flux and temperature within a single compact probe, MPFDs offer this option. MPFD construction is very different then current fission chamber construction; the use of high temperature materials allow MPFDs to be specifically tailored to survive harsh conditions in typical high performance MTR irradiation tests. New high-fidelity reactor physics codes will need a small, accurate, multipurpose in-core sensor to validate the codes without perturbing the validation experiment; MPFDs fill this requirement. MPFDs can be built with variable sensitivities to survive the lifetime of an experiment or fuel assembly in some MTRs; allowing for more efficient and cost effective power monitoring. The small size of the MPFDs allows multiple sensors to be simultaneously deployed; obtaining data required to visualize the reactor flux and temperature profiles. This report summarizes the research progress for year 1 of this 3 year project. An updated design of the MPFD has been developed, materials and tools to support the new design have been procured, construction methods to support the new design have been initiated at INL’s HTTL and KSU’s SMART Laboratory, plating methods are being updated at KSU, new detector electronics have been designed, built and tested at KSU. In addition, a project meeting was held at KSU and a detector evaluation plan has been initiated between INL and KSU. Once NEET program evaluations are completed, the final MPFD will be deployed in MTR irradiations, enabling DOE-NE programs evaluating the performance of candidate new fuels and materials to better characterize irradiation test conditions.

Troy Unruh; Joy Rempe; Douglas McGregor; Philip Ugorowski; Michael Reichenberger

2012-09-01T23:59:59.000Z

306

NEET Micro-Pocket Fission Detector – Final Project report  

SciTech Connect (OSTI)

A collaboration between the Idaho National Laboratory (INL), the Kansas State University (KSU), and the French Alternative Energies and Atomic Energy Commission, Commissariat à l'Énergie Atomique et aux Energies Alternatives, (CEA), is fundedby the Nuclear Energy Enabling Technologies (NEET) program to develop and test Micro-Pocket Fission Detectors (MPFDs), which are compact fission chambers capable of simultaneously measuring thermal neutron flux, fast neutron flux and temperature within a single package. When deployed, these sensors will significantly advance flux detection capabilities for irradiation tests in US Material Test Reactors (MTRs). Ultimately, evaluations may lead to a more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, and high performance reactors, allowing several Department of Energy Office of Nuclear Energy (DOE-NE) programs to obtain higher accuracy/higher resolution data from irradiation tests of candidate new fuels and materials. Specifically, deployment of MPFDs will address several challenges faced in irradiations performed at MTRs: • Current fission chamber technologies do not offer the ability to measure fast flux, thermal flux and temperature within a single compact probe; MPFDs offer this option. • MPFD construction is very different than current fission chamber construction; the use of high temperature materials allow MPFDs to be specifically tailored to survive harsh conditions encountered in-core of high performance MTRs. • The higher accuracy, high fidelity data available from the compact MPFD will significantly enhance efforts to validate new high-fidelity reactor physics codes and new multi-scale, multi-physics codes. • MPFDs can be built with variable sensitivities to survive the lifetime of an experiment or fuel assembly in some MTRs, allowing for more efficient and cost effective power monitoring. • The small size of the MPFDs allows multiple sensors to be deployed, offering the potential to accurately measure the flux and temperature profiles in the reactor. This report summarizes the status at the end of year two of this three year project. As documented in this report, all planned accomplishments for developing this unique new, compact, multipurpose sensor have been completed.

Joy Rempe; Douglas McGregor; Philip Ugorowski; Michael Reichenberger; Takashi Ito

2014-09-01T23:59:59.000Z

307

Fission meter and neutron detection using poisson distribution comparison  

DOE Patents [OSTI]

A neutron detector system and method for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. Comparison of the observed neutron count distribution with a Poisson distribution is performed to distinguish fissile material from non-fissile material.

Rowland, Mark S; Snyderman, Neal J

2014-11-18T23:59:59.000Z

308

Radiolysis Concerns for Water Shielding in Fission Surface Power Applications  

SciTech Connect (OSTI)

This paper presents an overview of radiolysis concerns with regard to water shields for fission surface power. A review of the radiolysis process is presented and key parameters and trends are identified. From this understanding of the radiolytic decomposition of water, shield pressurization and corrosion are identified as the primary concerns. Existing experimental and modeling data addressing concerns are summarized. It was found that radiolysis of pure water in a closed volume results in minimal, if any net decomposition, and therefore reduces the potential for shield pressurization and corrosion.

Schoenfeld, Michael P. [NASA Marshall Space Flight Center, ER24, MSFC, AL 35812 (United States); Anghaie, Samim [Innovative Space Power and Propulsion Institute, 800 SW Archer Rd. Bldg.554, P.O. Box 116502, University of Florida, Gainesville, FL 32611-6502 (United States)

2008-01-21T23:59:59.000Z

309

Singlet Fission | MIT-Harvard Center for Excitonics  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassiveSubmitted forHighlightsSeminarsSilicon spongeComputingCellFission April 3, 2012

310

Cryogenic method for measuring nuclides and fission gases  

DOE Patents [OSTI]

A cryogenic method is provided for determining airborne gases and particulates from which gamma rays are emitted. A special dewar counting vessel is filled with the contents of the sampling flask which is immersed in liquid nitrogen. A vertically placed sodium-iodide or germanium-lithium gamma-ray detector is used. The device and method are of particular use in measuring and identifying the radioactive noble gases including emissions from coal-fired power plants, as well as fission gases released or escaping from nuclear power plants.

Perdue, P.T.; Haywood, F.F.

1980-05-02T23:59:59.000Z

311

FLATNESS OF HEAV CHAIN SYSTEMS  

E-Print Network [OSTI]

a load, addressed in partial derivatives equations framework. parameterize system trajectories chain systems described by a one­dimensional (1D) partial di#erential wave equation. Dealing#erential equations, constant varying delay equations, even partial di#erential equations. these cases open­ loop

312

SUPPLY CHAIN MANAGER CHICAGO, IL  

E-Print Network [OSTI]

at project leader to bring best practices into the organization. He or she will recommend solutions to break developing new technology to meet the ever-changing demands of modern industry. The US Headquarters with broad responsibilities that include assessing, managing and improving the supply chain function

Smilowitz, Karen

313

A fission-fusion hybrid reactor in steady-state L-mode tokamak configuration with natural uranium  

E-Print Network [OSTI]

The most prevalent criticism of fission-fusion hybrids is simply that they are too exotic - that they would exacerbate the challenges of both fission and fusion. This is not really true. Intriguingly, hybrids could actually ...

Reed, Mark Wilbert

2011-01-01T23:59:59.000Z

314

Microfluidic chemical reaction circuits  

SciTech Connect (OSTI)

New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

Lee, Chung-cheng (Irvine, CA); Sui, Guodong (Los Angeles, CA); Elizarov, Arkadij (Valley Village, CA); Kolb, Hartmuth C. (Playa del Rey, CA); Huang, Jiang (San Jose, CA); Heath, James R. (South Pasadena, CA); Phelps, Michael E. (Los Angeles, CA); Quake, Stephen R. (Stanford, CA); Tseng, Hsian-rong (Los Angeles, CA); Wyatt, Paul (Tipperary, IE); Daridon, Antoine (Mont-Sur-Rolle, CH)

2012-06-26T23:59:59.000Z

315

Quantum and Thermodynamic Properties of Spontaneous and Low-Energy Induced Fission of Nuclei  

SciTech Connect (OSTI)

It is shown that A. Bohr's concept of transition fission states can be matched with the properties of Coriolis interaction if an axisymmetric fissile nucleus near the scission point remains cold despite a nonadiabatic character of nuclear collective deformation motion. The quantum and thermodynamic properties of various stages of binary and ternary fission after the descent of a fissile nucleus from the outer saddle point are studied within quantum-mechanical fission theory. It is shown that two-particle nucleon-nucleon correlations--in particular, superfluid correlations--play an important role in the formation of fission products and in the classification of fission transitions. The distributions of thermalized primary fission fragments with respect to spins and their projections onto the symmetry axis of the fissile nucleus and fission fragments are constructed, these distributions determining the properties of prompt neutrons and gamma rays emitted by these fragments. A new nonevaporation mechanism of third-particle production in ternary fission is proposed. This mechanism involves transitions of third particles from the cluster states of the fissile-nucleus neck to high-energy states under effects of the shake-off type that are due to the nonadiabatic character of nuclear collective deformation motion.

Kadmensky, S.G. [Voronezh State University, Universitetskaya pl. 1, Voronezh, 394693 (Russian Federation)

2005-12-01T23:59:59.000Z

316

Resonant tunneling and the bimodal symmetric fission of sup 258 Fm  

SciTech Connect (OSTI)

The concept of resonant tunneling is invoked to explain the sharp drop in the measured spontaneous-fission half-life when going from {sup 256}Fm to {sup 258}Fm. Various consequences of such a suggestion on the other observed characteristics of the bimodal symmetric fission of {sup 258}Fm are briefly discussed.

Bhandari, B.S. (Department of Physics, Faculty of Science, University of Garyounis, Benghazi, Libya (LY))

1991-02-25T23:59:59.000Z

317

INT Program 13-3 Quantitative Large Amplitude Shape Dynamics: fission and heavy ion fusion  

E-Print Network [OSTI]

INT Program 13-3 Quantitative Large Amplitude Shape Dynamics: fission and heavy ion fusion Workshop on: Experimental Status and Prospects October 14 - 18, 2013 Talks are 40 minutes long and followed and nuclear data Katsuhisa Nishio, JAEA 2:00 Fission shape evolution by Brownian motion Jorgen Randrup, LBNL 3

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

318

Structural basis for recruitment of mitochondrial fission complexes by Fis1  

E-Print Network [OSTI]

Structural basis for recruitment of mitochondrial fission complexes by Fis1 Yan Zhang and David C mitochondrial fission complex, the outer membrane protein Fis1 recruits the dynamin-related GTPase Dnm1 to mitochondria. Fis1 contains a tetratricopeptide repeat (TPR) domain and interacts with Dnm1 via the molecular

Chan, David

319

New fission fragment distributions and r-process origin of the rare-earth elements  

E-Print Network [OSTI]

Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 140.

Goriely, S; Lemaitre, J -F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H -Thomas

2013-01-01T23:59:59.000Z

320

(COMEDIE program review and fission product transport in MHTGR reactor)  

SciTech Connect (OSTI)

The subcontract between Martin Marietta Energy Systems, Inc., and the CEA provides for the refurbishment of the high pressure COMEDIE test loop in the SILOE reactor and a series of experiments to characterize fission product lift-off from MHTGR heat exchanger surfaces under several depressurization accident scenarios. The data will contribute to the validation of models and codes used to predict fission product transport in the MHTGR. In the meeting at CEA headquarters in Paris the program schedule and preparation for the DCAA and Quality Assurance audits were discussed. Long-range interest in expanded participation in the gas-cooled reactor technology Umbrella Agreement was also expressed by the CEA. At the CENG, in Grenoble, technical details on the loop design, fabrication components, development of test procedures, and preparation for the DOE quality assurance (QA) audit in May were discussed. After significant delays in CY 1989 it appears that good progress is being made in CY 1990 and the first major test will be initiated by December. An extensive list of agreements and commitments was generated to facilitate the coordination and planning of future work. 2 figs., 2 tabs.

Stansfield, O.M.

1990-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

The neutronics studies of fusion fission hybrid power reactor  

SciTech Connect (OSTI)

In this paper, a series of neutronics analysis of hybrid power reactor is proposed. The ideas of loading different fuels in a modular-type fission blanket is analyzed, fitting different level of fusion developments, i.e., the current experimental power output, the level can be obtained in the coming future and the high-power fusion reactor like ITER. The energy multiplication of fission blankets and tritium breeding ratio are evaluated as the criterion of design. The analysis is implemented based on the D-type simplified model, aiming to find a feasible 1000MWe hybrid power reactor for 5 years' lifetime. Three patterns are analyzed: 1) for the low fusion power, the reprocessed fuel is chosen. The fuel with high plutonium content is loaded to achieve large energy multiplication. 2) For the middle fusion power, the spent fuel from PWRs can be used to realize about 30 times energy multiplication. 3) For the high fusion power, the natural uranium can be directly used and about 10 times energy multiplication can be achieved.

Zheng Youqi; Wu Hongchun; Zu Tiejun; Yang Chao; Cao Liangzhi [School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049 (China)

2012-06-19T23:59:59.000Z

322

Angular distribution of products of ternary nuclear fission induced by cold polarized neutrons  

SciTech Connect (OSTI)

Within quantum fission theory, angular distributions of products originating from the ternary fission of nuclei that is induced by polarized cold and thermal neutrons are investigated on the basis of a non-evaporative mechanism of third-particle emission and a consistent description of fission-channel coupling. It is shown that the inclusion of Coriolis interaction both in the region of the discrete and in the region of the continuous spectrum of states of the system undergoing fission leads to T-odd correlations in the aforementioned angular distributions. The properties of the TRI and ROT effects discovered recently, which are due to the interference between the fission amplitudes of neutron resonances, are explored. The results obtained here are compared with their counterparts from classic calculations based on the trajectory method.

Bunakov, V. E., E-mail: bunakov@vb13190.spbu.edu; Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Kadmensky, S. S. [Voronezh State University (Russian Federation)

2008-11-15T23:59:59.000Z

323

P-odd and P-even correlations for third particles in ternary fission  

SciTech Connect (OSTI)

Within quantum-mechanical fission theory, P-odd and P-even correlations in angular distributions of products of the ternary fission of nuclei that is induced by polarized cold and thermal neutrons are investigated on the basis of a nonevaporative mechanism of third-particle emission and under the assumption that a two-humped fission barrier exists. It is shown that these correlations for third particles are induced by the analogous correlations for ternary-fission fragments, the latter being transferred to the third particle because of the kinematical conditions of third-particle emission that are associated with the charge and mass asymmetry of fragments. Optimum methods for observing the above correlations for third particles are discussed. The possibility of discovering the emission of prescission neutrons in the fission process against the background of evaporated neutrons by means of studying P-odd and P-even correlations is explored.

Bunakov, V. E., E-mail: bunakov@vb13190.spbu.edu; Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Titova, L. V. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation)

2008-12-15T23:59:59.000Z

324

Method for correcting for isotope burn-in effects in fission neutron dosimeters  

DOE Patents [OSTI]

A method is described for correcting for effect of isotope burn-in in fission neutron dosimeters. Two quantities are measured in order to quantify the "burn-in" contribution, namely P.sub.Z',A', the amount of (Z', A') isotope that is burned-in, and F.sub.Z', A', the fissions per unit volume produced in the (Z', A') isotope. To measure P.sub.Z', A', two solid state track recorder fission deposits are prepared from the very same material that comprises the fission neutron dosimeter, and the mass and mass density are measured. One of these deposits is exposed along with the fission neutron dosimeter, whereas the second deposit is subsequently used for observation of background. P.sub.Z', A' is then determined by conducting a second irradiation, wherein both the irradiated and unirradiated fission deposits are used in solid state track recorder dosimeters for observation of the absolute number of fissions per unit volume. The difference between the latter determines P.sub.Z', A' since the thermal neutron cross section is known. F.sub.Z', A' is obtained by using a fission neutron dosimeter for this specific isotope, which is exposed along with the original threshold fission neutron dosimeter to experience the same neutron flux-time history at the same location. In order to determine the fissions per unit volume produced in the isotope (Z', A') as it ingrows during the irradiation, B.sub.Z', A', from these observations, the neutron field must generally be either time independent or a separable function of time t and neutron energy E.

Gold, Raymond (Richland, WA); McElroy, William N. (Richland, WA)

1988-01-01T23:59:59.000Z

325

Nuclear Instruments and Methods in Physics Research A 554 (2005) 340346 A compensated fission detector based on photovoltaic cells  

E-Print Network [OSTI]

detector based on photovoltaic cells M. Petita , T. Ethvignota , T. Graniera,Ã?, R.C. Haightb , J.M. O fission fragment detector based on compensated photovoltaic cells has been developed. The compensated. Keywords: Fission; Fission detection; Compensated detector; Lead slowing-down spectrometer; Photovoltaic

Danon, Yaron

326

Supply chain management in the cement industry  

E-Print Network [OSTI]

Traditionally supply chain management has played an operational role within cement and mineral extraction commodity companies. Recently, cost reduction projects have brought supply chain management into the limelight. In ...

Agudelo, Isabel

2009-01-01T23:59:59.000Z

327

Supply Chain Management Faculty Brian Fugate  

E-Print Network [OSTI]

relationships, strategy and sustainability in the supply chain, and she won the College of Business Excellence involvement in new product development, and sustainability practices in supply chain management. He has

328

An integrative framework for architecting supply chains  

E-Print Network [OSTI]

This thesis explores the limitations of classic models of supply chain management, and proposes a new view based on the concept of value-driven supply chains, and a method of analysis and design based on the concepts of ...

Cela Díaz, Fernando

2006-01-01T23:59:59.000Z

329

Charlotte Green Supply Chain: Residential Retrofitting | Department...  

Broader source: Energy.gov (indexed) [DOE]

Charlotte Green Supply Chain: Residential Retrofitting Charlotte Green Supply Chain: Residential Retrofitting July 30, 2010 - 10:50am Addthis Joshua DeLung What does this mean for...

330

Loss of coordination in competitive supply chains  

E-Print Network [OSTI]

The loss of coordination in supply chains quantifies the inefficiency (i.e. the loss of total profit) due to the presence of competition in the supply chain. In this thesis, we discuss four models: one model with multiple ...

Teo, Koon Soon

2009-01-01T23:59:59.000Z

331

Harmonic Chain with Weak Dissipation  

E-Print Network [OSTI]

We consider finite harmonic chain (consisting of N classical particles) plus dissipative force acting on one particle (called dissipating particle) only. We want to prove that "in the generic case" the energy (per particle) for the whole system tends to zero in the large time limit and then in the large N limit. "In the generic case" means: for almost all initial conditions and for almost any choice of the dissipating particle, in the thermodynamic limit.

A. A. Lykov; V. A. Malyshev

2013-02-20T23:59:59.000Z

332

Agents on the Web Supply Chains  

E-Print Network [OSTI]

Agents on the Web Automating Supply Chains 90 JULY · AUGUST 2001 http://computer.org/internet/ 1089

Almor, Amit

333

Physical Mechanism of Nuclear Reactions at Low Energies  

E-Print Network [OSTI]

The physical mechanism of nuclear reactions at low energies caused by spatial extension of electron is considered. Nuclear reactions of this type represent intra-electronic processes, more precisely, the processes occurring inside the area of basic localization of electron. Distinctive characteristics of these processes are defined by interaction of the own field produced by electrically charged matter of electron with free nuclei. Heavy nucleus, appearing inside the area of basic localization of electron, is inevitably deformed because of interaction of protons with the adjoining layers of electronic cloud, which may cause nuclear fission. If there occur "inside" electron two or greater number of light nuclei, an attractive force appears between the nuclei which may result in the fusion of nuclei. The intra-electronic mechanism of nuclear reactions is of a universal character. For its realization it is necessary to have merely a sufficiently intensive stream of free electrons, i.e. heavy electric current, and as long as sufficiently great number of free nuclei. This mechanism may operate only at small energies of translational motion of the centers of mass of nuclei and electron. Because of the existence of simple mechanism of nuclear reactions at low energies, nuclear reactor turns out to be an atomic delayed-action bomb which may blow up by virtue of casual reasons, as it has taken place, apparently, in Chernobyl. The use of cold nuclear reactions for production of energy will provide mankind with cheap, practically inexhaustible, and non-polluting energy sources.

V. P. Oleinik; Yu. D Arepjev

2003-06-09T23:59:59.000Z

334

The Offshore Services Global Value Chain  

E-Print Network [OSTI]

The Offshore Services Global Value Chain ECONOMIC UPGRADING AND WORKFORCE DEVELOPMENT Karina & COMPETITIVENESS #12;The Offshore Services Global Value Chain: Economic Upgrading and Workforce Development "Skills & Competitiveness, Duke University Posted: November 17, 2011 #12;The Offshore Services Global Value Chain: Economic

Richardson, David

335

Supply Chain and Information Sciences Technology 2010  

E-Print Network [OSTI]

Supply Chain and Information Sciences Technology 2010 Supply Chain and Information Systems Technology Minor SCIST Minor Application Department of Supply Chain & Information Systems College of Information Sciences and Technology Overview The minor in SCIST is structured to provide students not majoring

Guiltinan, Mark

336

Rapid disappearance of shell effects in the fission of transfermium nuclei  

SciTech Connect (OSTI)

In the last fifteen years we have learned that nuclear shells have a very broad and pervasive impact on the fission process. In the first few decades after the discovery of nuclear fission, the nucleus was treated as a drop of liquid with smoothly varying attractive and repulsive forces. Although this model still forms the underlying basis for fission, we also observe large effects from the superimposition of shell corrections derived from coupling the quantum states of individual nucleons. The consequences of single-particle coupling on the fission process can be striking and may often overshadow that originating from the intrinsic liquid-drop component. Here, we point out several major features attributable to shell effects in the spontaneous fission (SF) of the lighter actinides, the sudden transition to symmetric fission in the fermium isotopes, and finally new experimental information indicating another transition in the SF of transfermium nuclides due to the disappearance of shell perturbations. In each transition, the abruptness is surprising, and for the moment, such rapid changes in fission behavior lack a theoretical rationale.

Hulet, E.K.

1983-01-01T23:59:59.000Z

337

Uncertainty and sensitivity analysis of fission gas behavior in engineering-scale fuel modeling  

SciTech Connect (OSTI)

The role of uncertainties in fission gas behavior calculations as part of engineering-scale nuclear fuel modeling is investigated using the BISON fuel performance code and a recently implemented physics-based model for the coupled fission gas release and swelling. Through the integration of BISON with the DAKOTA software, a sensitivity analysis of the results to selected model parameters is carried out based on UO2 single-pellet simulations covering different power regimes. The parameters are varied within ranges representative of the relative uncertainties and consistent with the information from the open literature. The study leads to an initial quantitative assessment of the uncertainty in fission gas behavior modeling with the parameter characterization presently available. Also, the relative importance of the single parameters is evaluated. Moreover, a sensitivity analysis is carried out based on simulations of a fuel rod irradiation experiment, pointing out a significant impact of the considered uncertainties on the calculated fission gas release and cladding diametral strain. The results of the study indicate that the commonly accepted deviation between calculated and measured fission gas release by a factor of 2 approximately corresponds to the inherent modeling uncertainty at high fission gas release. Nevertheless, higher deviations may be expected for values around 10% and lower. Implications are discussed in terms of directions of research for the improved modeling of fission gas behavior for engineering purposes.

G. Pastore; L.P. Swiler; J.D. Hales; S.R. Novascone; D.M. Perez; B.W. Spencer; L. Luzzi; P. Van Uffelen; R.L. Williamson

2014-10-01T23:59:59.000Z

338

Thermal Performance of Deep-Burn Fusion-Fission Hybrid Waste in a Repository  

SciTech Connect (OSTI)

The Laser Inertial Confinement Fusion Fission Energy (LIFE) Engine [1] combines a neutron-rich but energy-poor inertial fusion system with an energy-rich but neutron-poor subcritical fission blanket. Because approximately 80% of the LIFE Engine energy is produced from fission, the requirements for laser efficiency and fusion target performance are relaxed, compared to a pure-fusion system, and hence a LIFE Engine prototype can be based on target performance in the first few years of operation of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). Similarly, because of the copious fusion neutrons, the fission blanket can be run in a subcritical, driven, mode, without the need for control rods or other sophisticated reactivity control systems. Further, because the fission blanket is inherently subcritical, fission fuels that can be used in LIFE Engine designs include thorium, depleted uranium, natural uranium, spent light water reactor fuel, highly enriched uranium, and plutonium. Neither enrichment nor reprocessing is required for the LIFE Engine fuel cycle, and burnups to 99% fraction of initial metal atoms (FIMA) being fissioned are envisioned. This paper discusses initial calculations of the thermal behavior of spent LIFE fuel following completion of operation in the LIFE Engine [2]. The three time periods of interest for thermal calculations are during interim storage (probably at the LIFE Engine site), during the preclosure operational period of a geologic repository, and after closure of the repository.

Blink, J A; Chipman, V; Farmer, J; Shaw, H; Zhao, P

2008-11-25T23:59:59.000Z

339

Fission product behavior during the PBF (Power Burst Facility) Severe Fuel Damage Test 1-1  

SciTech Connect (OSTI)

In response to the accident at Three Mile Island Unit 2 (TMI-2), the United States Nuclear Regulatory Commission (USNRC) initiated a series of Severe Fuel Damage tests that were performed in the Power Burst Facility at the Idaho National Engineering Laboratory to obtain data necessary to understand (a) fission product release, transport, and deposition; (b) hydrogen generation; and (c) fuel/cladding material behavior during degraded core accidents. Data are presented about fission product behavior noted during the second experiment of this series, the Severe Fuel Damage Test 1-1, with an in-depth analysis of the fission product release, transport, and deposition phenomena that were observed. Real-time release and transport data of certain fission products were obtained from on-line gamma spectroscopy measurements. Liquid and gas effluent grab samples were collected at selected periods during the test transient. Additional information was obtained from steamline deposition analysis. From these and other data, fission product release rates and total release fractions are estimated and compared with predicted release behavior using current models. Fission product distributions and a mass balance are also summarized, and certain probable chemical forms are predicted for iodine, cesium, and tellurium. An in-depth evaluation of phenomena affecting the behavior of the high-volatility fission products - xenon, krypton, iodine, cesium, and tellurium - is presented. Analysis indicates that volatile release from fuel is strongly influenced by parameters other than fuel temperature. Fission product behavior during transport through the Power Burst Facility effluent line to the fission product monitoring system is assessed. Tellurium release behavior is also examined relatve to the extent of Zircaloy cladding oxidation. 81 fig., 53 tabs.

Hartwell, J K; Petti, D A; Hagrman, D L; Jensen, S M; Cronenberg, A W

1987-05-01T23:59:59.000Z

340

Method for polymer synthesis in a reaction well  

DOE Patents [OSTI]

A method of synthesis for building a polymer chain, oligonucleotides in particular, by sequentially adding monomer units to at least one solid support for growing and immobilizing a polymer chain thereon in a liquid reagent solution. The method includes the step of: A) depositing a liquid reagent in a reaction well (26) in contact with at least one solid support and at least one monomer unit of the polymer chain affixed to the solid support. The well (26) includes at least one orifice (74) extending into the well (26), and is of a size and dimension to form a capillary liquid seal to retain the reagent solution in the well (26) to enable polymer chain growth on the solid support. The method further includes the step of B) expelling the reagent solution from the well (26), while retaining the polymer chain therein. This is accomplished by applying a first gas pressure to the reaction well such that a pressure differential between the first gas pressure and a second gas pressure exerted on an exit (80) of the orifice (74) exceeds a predetermined amount sufficient to overcome the capillary liquid seal and expel the reagent solution from the well (26) through the orifice exit (80).

Brennan, Thomas M. (San Francisco, CA)

1998-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Method for polymer synthesis in a reaction well  

DOE Patents [OSTI]

A method of synthesis is described for building a polymer chain, oligonucleotides in particular, by sequentially adding monomer units to at least one solid support for growing and immobilizing a polymer chain thereon in a liquid reagent solution. The method includes the step of: (A) depositing a liquid reagent in a reaction well in contact with at least one solid support and at least one monomer unit of the polymer chain affixed to the solid support. The well includes at least one orifice extending into the well, and is of a size and dimension to form a capillary liquid seal to retain the reagent solution in the well to enable polymer chain growth on the solid support. The method further includes the step of (B) expelling the reagent solution from the well, while retaining the polymer chain therein. This is accomplished by applying a first gas pressure to the reaction well such that a pressure differential between the first gas pressure and a second gas pressure exerted on an exit of the orifice exceeds a predetermined amount sufficient to overcome the capillary liquid seal and expel the reagent solution from the well through the orifice exit. 9 figs.

Brennan, T.M.

1998-09-29T23:59:59.000Z

342

Beta-delayed fission and the production of very heavy nuclides from rapid neutron capture processes  

E-Print Network [OSTI]

The experimental probabilities are larger than expected, indicating an increase in level densities above the fission barriers due to the loss of symmetry at the inner barrier. As a consequence beta delayed fission may occur also in the r-process path. When discussing the production of superheavy nuclides by the r-process, beta delayed fission has therefore to be considered not only in the decay back but also for the cut-off. The results from earlier calculations on the yield of stable nuclides from nuclear explosions and r-process production ratios for chronometric pairs are carried over into a new model with only small changes. (21 refs).

Wene, C O

1976-01-01T23:59:59.000Z

343

Detecting special nuclear materials in containers using high-energy gamma rays emitted by fission products  

DOE Patents [OSTI]

A method and a system for detecting the presence of special nuclear materials in a container. The system and its method include irradiating the container with an energetic beam, so as to induce a fission in the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

Norman, Eric B. (Oakland, CA); Prussin, Stanley G. (Kensington, CA)

2007-10-02T23:59:59.000Z

344

Background and Derivation of ANS-5.4 Standard Fission Product Release Model  

SciTech Connect (OSTI)

This background report describes the technical basis for the newly proposed American Nuclear Society (ANS) 5.4 standard, Methods for Calculating the Fractional Release of Volatile Fission Products from Oxide Fuels. The proposed ANS 5.4 standard provides a methodology for determining the radioactive fission product releases from the fuel for use in assessing radiological consequences of postulated accidents that do not involve abrupt power transients. When coupled with isotopic yields, this method establishes the 'gap activity,' which is the inventory of volatile fission products that are released from the fuel rod if the cladding are breached.

Beyer, Carl E.; Turnbull, Andrew J.

2010-01-29T23:59:59.000Z

345

Radiological Aspects of Deep-Burn Fusion-Fission Hybrid Waste in a Repository  

SciTech Connect (OSTI)

The quantity, radioactivity, and isotopic characteristics of the spent fission fuel from a hybrid fusion-fission system capable of extremely high burnups are described. The waste generally has higher activity per unit mass of heavy metal, but much lower activity per unit energy generated. The very long-term radioactivity is dominated by fission products. Simple scaling calculations suggest that the dose from a repository containing such waste would be dominated by {sup 129}I, {sup 135}Cs, and {sup 242}Pu. Use of such a system for generating energy would greatly reduce the need for repository capacity.

Shaw, H F; Blink, J A; Farmer, J C; Karmer, K J; Latkowski, J F; Zhao, P

2008-11-25T23:59:59.000Z

346

Deep Atomic Binding (DAB) Approach in Interpretation of Fission Products Behavior in Terrestrial and Water Ecosystems  

SciTech Connect (OSTI)

A large number of studies and models were established to explain the fission products (FP) behavior within terrestrial and water ecosystems, but a number of behaviors were non understandable, which always attributed to unknown reasons. According to DAB hypothesis, almost all fission products behaviors in terrestrial and water ecosystems could be interpreted in a wide coincidence. The gab between former models predictions, and field behavior of fission products after accidents like Chernobyl have been explained. DAB represents a tool to reduce radio-phobia as well as radiation protection expenses. (author)

Ajlouni, Abdul-Wali M.S. [Ministry of Energy and Mineral Resources, Amman 11814 (Jordan)

2006-07-01T23:59:59.000Z

347

Single chain elasticity and thermoelasticity of polyethylene  

E-Print Network [OSTI]

Single-chain elasticity of polyethylene at $\\theta$ point up to 90% of stretching with respect to its contour length is computed by Monte-Carlo simulation of an atomistic model in continuous space. The elasticity law together with the free-energy and the internal energy variations with stretching are found to be very well represented by the wormlike chain model up to 65% of the chain elongation, provided the persistence length is treated as a temperature dependent parameter. Beyond this value of elongation simple ideal chain models are not able to describe the Monte Carlo data in a thermodynamic consistent way. This study reinforces the use of the wormlike chain model to interpret experimental data on the elasticity of synthetic polymers in the finite extensibility regime, provided the chain is not yet in its fully stretched regime. Specific solvent effects on the elasticity law and the partition between energetic and entropic contributions to single chain elasticity are investigated.

John T. Titantah; Carlo Pierleoni; Jean-Paul Ryckaert

2002-09-05T23:59:59.000Z

348

The LHC Lead Injector Chain  

E-Print Network [OSTI]

A sizeable part of the LHC physics programme foresees lead-lead collisions with a design luminosity of 1027 cm-2 s-1. This will be achieved after an upgrade of the ion injector chain comprising Linac3, LEIR, PS and SPS machines [1,2]. Each LHC ring will be filled in 10 min by almost 600 bunches, each of 7×107 lead ions. Central to the scheme is the Low Energy Ion Ring (LEIR) [3,4], which transforms long pulses from Linac3 into high-brilliance bunches by means of multi-turn injection, electron cooling and accumulation. Major limitations along the chain, including space charge, intrabeam scattering, vacuum issues and emittance preservation are highlighted. The conversion from LEAR (Low Energy Antiproton Ring) to LEIR involves new magnets and power converters, high-current electron cooling, broadband RF cavities, and a UHV vacuum system with getter (NEG) coatings to achieve a few 10-12 mbar. Major hardware changes in Linac3 and the PS are also covered. An early ion scheme with fewer bunches (but each at nominal...

Beuret, A; Blas, A; Burkhardt, H; Carli, Christian; Chanel, M; Fowler, A; Gourber-Pace, M; Hancock, S; Hourican, M; Hill, C E; Jowett, John M; Kahle, K; Küchler, D; Lombardi, A M; Mahner, E; Manglunki, Django; Martini, M; Maury, S; Pedersen, F; Raich, U; Rossi, C; Royer, J P; Schindl, Karlheinz; Scrivens, R; Sermeus, L; Shaposhnikova, Elena; Tranquille, G; Vretenar, Maurizio; Zickler, T

2004-01-01T23:59:59.000Z

349

Continuous chain bit with downhole cycling capability  

DOE Patents [OSTI]

A continuous chain bit for hard rock drilling is capable of downhole cycling. A drill head assembly moves axially relative to a support body while the chain on the head assembly is held in position so that the bodily movement of the chain cycles the chain to present new composite links for drilling. A pair of spring fingers on opposite sides of the chain hold the chain against movement. The chain is held in tension by a spring-biased tensioning bar. A head at the working end of the chain supports the working links. The chain is centered by a reversing pawl and piston actuated by the pressure of the drilling mud. Detent pins lock the head assembly with respect to the support body and are also operated by the drilling mud pressure. A restricted nozzle with a divergent outlet sprays drilling mud into the cavity to remove debris. Indication of the centered position of the chain is provided by noting a low pressure reading indicating proper alignment of drilling mud slots on the links with the corresponding feed branches.

Ritter, Don F. (Albuquerque, NM); St. Clair, Jack A. (Albuquerque, NM); Togami, Henry K. (Albuquerque, NM)

1983-01-01T23:59:59.000Z

350

Ternary particles with extreme N/Z ratios from neutron-induced fission  

SciTech Connect (OSTI)

The existing ternary fission models can well reproduce the yields of the most abundant light charged particles. However, these models tend to significantly overestimate the yields of ternary particles with an extreme N/Z ratio: {sup 3}He, {sup 11}Li, {sup 14}Be, etc. The experimental yields of these isotopes were investigated with the recoil separator LOHENGRIN down to a level of 10{sup {minus}10} per fission. Results from the fissioning systems {sup 233}U (n{sub th}, f), {sup 235}U(n{sub th},f), {sup 239}Pu(n{sub th},f) {sup 241}Pu(n{sub th},f) and {sup 245}Cm(n{sub th},f) are presented and the implications for the ternary fission models are discussed.

Koster, U.; Faust, H.; Friedrichs, T.; Oberstedt, S.; Fioni, G.; Grob, M.; Ahmad, I. J.; Devlin, M.; Heinz, A.; Kondev, F. G.; Lauritsen, T.; Sarantites, D. G.; Siem, S.; Sobotka, L. G.; Sonzogni, A.

2000-05-16T23:59:59.000Z

351

/sup 3/He-induced fission of nuclei 159  

SciTech Connect (OSTI)

The fission of nuclei with 159< or =A< or =232 induced by the bombardment of 19.1 to 44.5 MeV /sup 3/He ions has been measured using solid-state detectors with time-of-flight measurements. Analysis with statistical fission theory, including precompound nucleon emission, indicates fission barriers which decrease only slightly relative to the liquid-drop model values with decreasing Z, approaching about 90% of the liquid-drop model barrier for Aroughly-equal160. These results are in contrast with measurements at higher angular momenta which indicate much lower fission barriers (60 to 70 % of the liquid-drop model) for this mass region. The angular correlations indicate complete, or slightly greater than complete momentum transfer to the compound system. This is in opposition to that observed using heavier projectiles where incomplete momentum transfer is probable.

Becchetti, F.D.; Hicks, K.H.; Fields, C.A.; Peterson, R.J.; Raymond, R.S.; Ristinen, R.A.; Ullmann, J.L.; Zaidins, C.S.

1983-09-01T23:59:59.000Z

352

E-Print Network 3.0 - amount gaseous fission Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

) reports that the amount of non-gaseous nuclides retained on the filters of the Windscale pile... . Petersen Abstract. The fission-product release to the atmosphere from a...

353

Enhanced external quantum efficiency in an organic photovoltaic cell via singlet fission exciton sensitizer  

E-Print Network [OSTI]

We demonstrate bilayer organic photovoltaic cells that incorporate a singlet exciton fission sensitizer layer to increase the external quantum efficiency (EQE). This solar cell architecture is realized by pairing the singlet ...

Reusswig, Philip David

354

E-Print Network 3.0 - absolute fission yields Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Physics 90 H-atom high-n Rydberg time-of-flight spectroscopy of CH bond fission in acrolein dissociated at 193 nm Summary: H-atom high-n Rydberg time-of-flight spectroscopy of...

355

Recent Results and Fabrication of Micro-Pocket Fission Detectors (MPFD)  

E-Print Network [OSTI]

environments found in a reactor core. Self-powered neutron detectors (SPND) have the advantages of no voltage to noise ratio of the fission and ionization chambers, the low voltage requirements and small size of SPND

Shultis, J. Kenneth

356

Geminate and non-geminate recombination of triplet excitons formed by singlet fission  

E-Print Network [OSTI]

fis- sion material would ideally have degenerate singlet and triplet-pair states. However, with this energy level con- figuration, the inverse process of singlet fission - triplet- triplet annihilation - becomes a possible recombination pathway...

Bayliss, Sam L.; Chepelianskii, Alexei D.; Sepe, Alessandro; Walker, Brian J.; Ehrler, Bruno; Bruzek, Matthew J.; Anthony, John E.; Greenham, Neil C.

2014-07-04T23:59:59.000Z

357

Slow light enhanced singlet exciton fission solar cells with a 126% yield of electrons per photon  

E-Print Network [OSTI]

Singlet exciton fission generates two triplet excitons per absorbed photon. It promises to increase the power extracted from sunlight without increasing the number of photovoltaic junctions in a solar cell. We demonstrate ...

Thompson, Nicholas J.

358

Molten salt considerations for accelerator-driven subcritical fission to close the nuclear fuel cycle  

SciTech Connect (OSTI)

The host salt selection, molecular modeling, physical chemistry, and processing chemistry are presented here for an accelerator-driven subcritical fission in a molten salt core (ADSMS). The core is fueled solely with the transuranics (TRU) and long-lived fission products (LFP) from used nuclear fuel. The neutronics and salt composition are optimized to destroy the transuranics by fission and the long-lived fission products by transmutation. The cores are driven by proton beams from a strong-focusing cyclotron stack. One such ADSMS system can destroy the transuranics in the used nuclear fuel produced by a 1GWe conventional reactor. It uniquely provides a method to close the nuclear fuel cycle for green nuclear energy.

Sooby, Elizabeth; Baty, Austin; Gerity, James; McIntyre, Peter; Melconian, Karie; Pogue, Nathaniel; Sattarov, Akhdiyor [Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station TX 77843 (United States); Adams, Marvin; Tsevkov, Pavel [Nuclear Engineering, Texas A and M University, Spence St., College Station TX 77843 (United States); Phongikaroon, Supathorn [Center for Advanced Energy Studies, University of Idaho, 995 University Blvd, Idaho Falls, ID 83401 (United States); Simpson, Michael; Tripathy, Prabhat [Materials Fuels Complex, Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

2013-04-19T23:59:59.000Z

359

Detailed Chemical Kinetic Reaction Mechanism for Biodiesel Components Methyl Stearate and Methyl Oleate  

SciTech Connect (OSTI)

New chemical kinetic reaction mechanisms are developed for two of the five major components of biodiesel fuel, methyl stearate and methyl oleate. The mechanisms are produced using existing reaction classes and rules for reaction rates, with additional reaction classes to describe other reactions unique to methyl ester species. Mechanism capabilities were examined by computing fuel/air autoignition delay times and comparing the results with more conventional hydrocarbon fuels for which experimental results are available. Additional comparisons were carried out with measured results taken from jet-stirred reactor experiments for rapeseed methyl ester fuels. In both sets of computational tests, methyl oleate was found to be slightly less reactive than methyl stearate, and an explanation of this observation is made showing that the double bond in methyl oleate inhibits certain low temperature chain branching reaction pathways important in methyl stearate. The resulting detailed chemical kinetic reaction mechanism includes more approximately 3500 chemical species and more than 17,000 chemical reactions.

Naik, C; Westbrook, C K; Herbinet, O; Pitz, W J; Mehl, M

2010-01-22T23:59:59.000Z

360

The use of accelerators for the study of delayed neutrons from fission: Significance to reactor control  

SciTech Connect (OSTI)

Delayed neutrons from fission are very important in the kinetic behaviour of nuclear reactors and in the assaying of nuclear materials. Information is necessary on lifetimes, yields, and energies, and the paper shows the part which accelerators have played in providing it. Special attention is paid to yields and to recent measurements of delayed-neutron energies in fast fission; attention is drawn to gaps or uncertainties in knowledge and, therefore, to the need for new measurements.

Walker, J.; Owen, J.G.; Weaver, D.R.

1981-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

A comparison of radioactive waste from first generation fusion reactors and fast fission reactors with actinide recycling  

SciTech Connect (OSTI)

Limitations of the fission fuel resources will presumably mandate the replacement of thermal fission reactors by fast fission reactors that operate on a self-sufficient closed fuel cycle. This replacement might take place within the next one hundred years, so the direct competitors of fusion reactors will be fission reactors of the latter rather than the former type. Also, fast fission reactors, in contrast to thermal fission reactors, have the potential for transmuting long-lived actinides into short-lived fission products. The associated reduction of the long-term activation of radioactive waste due to actinides makes the comparison of radioactive waste from fast fission reactors to that from fusion reactors more rewarding than the comparison of radioactive waste from thermal fission reactors to that from fusion reactors. Radioactive waste from an experimental and a commercial fast fission reactor and an experimental and a commercial fusion reactor has been characterized. The fast fission reactors chosen for this study were the Experimental Breeder Reactor 2 and the Integral Fast Reactor. The fusion reactors chosen for this study were the International Thermonuclear Experimental Reactor and a Reduced Activation Ferrite Helium Tokamak. The comparison of radioactive waste parameters shows that radioactive waste from the experimental fast fission reactor may be less hazardous than that from the experimental fusion reactor. Inclusion of the actinides would reverse this conclusion only in the long-term. Radioactive waste from the commercial fusion reactor may always be less hazardous than that from the commercial fast fission reactor, irrespective of the inclusion or exclusion of the actinides. The fusion waste would even be far less hazardous, if advanced structural materials, like silicon carbide or vanadium alloy, were employed.

Koch, M.; Kazimi, M.S.

1991-04-01T23:59:59.000Z

362

Beta-delayed fission and neutron emission calculations for the actinide cosmochronometers  

SciTech Connect (OSTI)

The Gamow-Teller beta-strength distributions for 19 neutron-rich nuclei, including ten of interest for the production of the actinide cosmochronometers, are computed microscopically with a code that treats nuclear deformation explicitly. The strength distributions are then used to calculate the beta-delayed fission, neutron emission, and gamma deexcitation probabilities for these nuclei. Fission is treated both in the complete damping and WKB approximations for penetrabilities through the nuclear potential-energy surface. The resulting fission probabilities differ by factors of 2 to 3 or more from the results of previous calculations using microscopically computed beta-strength distributions around the region of greatest interest for production of the cosmochronometers. The indications are that a consistent treatment of nuclear deformation, fission barriers, and beta-strength functions is important in the calculation of delayed fission probabilities and the production of the actinide cosmochronometers. Since we show that the results are very sensitive to relatively small changes in model assumptions, large chronometric ages for the Galaxy based upon high beta-delayed fission probabilities derived from an inconsistent set of nuclear data calculations must be considered quite uncertain.

Meyer, B.S.; Howard, W.M.; Mathews, G.J.; Takahashi, K.; Moeller, P.; Leander, G.A.

1989-05-01T23:59:59.000Z

363

Microscopic description of fission in Uranium isotopes with the Gogny energy density functional  

E-Print Network [OSTI]

The most recent parametrizations D1S, D1N and D1M of the Gogny energy density functional are used to describe fission in the isotopes $^{232-280}$ U. Fission paths, collective masses and zero point quantum corrections, obtained within the constrained Hartree-Fock-Bogoliubov approximation, are used to compute the systematics of the spontaneous fission half-lives $t_\\mathrm{SF}$, the masses and charges of the fission fragments as well as their intrinsic shapes. The Gogny-D1M parametrization has been benchmarked against available experimental data on inner and second barrier heights, excitation energies of the fission isomers and half-lives in a selected set of Pu, Cm, Cf, Fm, No, Rf, Sg, Hs and Fl nuclei. It is concluded that D1M represents a reasonable starting point to describe fission in heavy and superheavy nuclei. Special attention is also paid to understand the uncertainties in the predicted $t_\\mathrm{SF}$ values arising from the different building blocks entering the standard semi-classical Wentzel-Kramers-Brillouin formula. Although the uncertainties are large, the trend with mass or neutron numbers are well reproduced and therefore the theory still has predictive power. In this respect, it is also shown that modifications of a few per cent in the pairing strength can have a significant impact on the collective masses leading to uncertainties in the $t_\\mathrm{SF}$ values of several orders of magnitude.

R. Rodriguez-Guzman; L. M. Robledo

2014-05-25T23:59:59.000Z

364

Optimizing a Retailer's Containerized Import Supply Chain  

E-Print Network [OSTI]

M.G. , 2005. Distribution network design: New problems andapproach for distribution chain design in agile virtualinto a strategic distribution network design model with

Davidson, Evan Taitz

2012-01-01T23:59:59.000Z

365

SNIF: A Futuristic Neutrino Probe for Undeclared Nuclear Fission Reactors  

E-Print Network [OSTI]

Today reactor neutrino experiments are at the cutting edge of fundamental research in particle physics. Understanding the neutrino is far from complete, but thanks to the impressive progress in this field over the last 15 years, a few research groups are seriously considering that neutrinos could be useful for society. The International Atomic Energy Agency (IAEA) works with its Member States to promote safe, secure and peaceful nuclear technologies. In a context of international tension and nuclear renaissance, neutrino detectors could help IAEA to enforce the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). In this article we discuss a futuristic neutrino application to detect and localize an undeclared nuclear reactor from across borders. The SNIF (Secret Neutrino Interactions Finder) concept proposes to use a few hundred thousand tons neutrino detectors to unveil clandestine fission reactors. Beyond previous studies we provide estimates of all known background sources as a function of the detector's longitude, latitude and depth, and we discuss how they impact the detectability.

Thierry Lasserre; Maximilien Fechner; Guillaume Mention; Romain Reboulleau; Michel Cribier; Alain Letourneau; David Lhuillier

2010-11-16T23:59:59.000Z

366

Micro-Pocket Fission Detectors (MPFD) For Fuel Assembly Analysis  

SciTech Connect (OSTI)

Neutron sensors capable of real-time measurement of thermal flux, fast flux, and temperature in a single miniaturized probe are needed in irradiation tests required to demonstrate the performance of candidate new fuels, and cladding materials. In-core ceramic-based miniature neutron detectors or “Micro-Pocket Fission Detectors” (MPFDs) have been studied at Kansas State University (KSU). The first MPFD prototypes were tested in various neutron fields at the KSU TRIGA research reactor with successful results. Currently, a United States Department of Energy-sponsored joint KSU/Idaho National Laboratory (INL) effort is underway to develop a high-temperature, high-pressure version of the MPFD using radiation-resistant, high temperature materials, which would be capable of withstanding irradiation test conditions in high performance material and test reactors (MTRs). Ultimately, this more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, existing and advanced reactor designs, high performance MTRs, and transient test reactors has the potential to lead to higher accuracy and resolution data from irradiation testing, more detailed core flux measurements and enhanced fuel assembly processing. Prior evaluations by KSU indicate that these sensors could also be used to monitor burn-up of nuclear fuel. If integrated into nuclear fuel assemblies, MPFDs offer several advantages to current spent fuel management systems.

Troy Unruh; Michael Reichenberger; Phillip Ugorowski

2013-09-01T23:59:59.000Z

367

Baseline Glass Development for Combined Fission Products Waste Streams  

SciTech Connect (OSTI)

Borosilicate glass was selected as the baseline technology for immobilization of the Cs/Sr/Ba/Rb (Cs), lanthanide (Ln) and transition metal fission product (TM) waste steams as part of a cost benefit analysis study.[1] Vitrification of the combined waste streams have several advantages, minimization of the number of waste forms, a proven technology, and similarity to waste forms currently accepted for repository disposal. A joint study was undertaken by Pacific Northwest National Laboratory (PNNL) and Savannah River National Laboratory (SRNL) to develop acceptable glasses for the combined Cs + Ln + TM waste streams (Option 1) and Cs + Ln combined waste streams (Option 2) generated by the AFCI UREX+ set of processes. This study is aimed to develop baseline glasses for both combined waste stream options and identify key waste components and their impact on waste loading. The elemental compositions of the four-corners study were used along with the available separations data to determine the effect of burnup, decay, and separations variability on estimated waste stream compositions.[2-5] Two different components/scenarios were identified that could limit waste loading of the combined Cs + LN + TM waste streams, where as the combined Cs + LN waste stream has no single component that is perceived to limit waste loading. Combined Cs + LN waste stream in a glass waste form will most likely be limited by heat due to the high activity of Cs and Sr isotopes.

Crum, Jarrod V.; Billings, Amanda Y.; Lang, Jesse B.; Marra, James C.; Rodriguez, Carmen P.; Ryan, Joseph V.; Vienna, John D.

2009-06-29T23:59:59.000Z

368

New developments in direct nuclear fission energy conversion devices  

SciTech Connect (OSTI)

Some experimental and theoretical results obtained in the investigations undertaken at the Central Institute of Physics (CIP) in Bucharest-Romania concerning the direct nuclear energy conversion into electrical energy are presented. Open-circuit voltages (U /SUB oc/ ) of tens of kV and short-circuit currents (J /SUB sc/ ) of several ..mu..A were obtained in experiments with vacuum fission-electric cells (FEC) developed in the CIP and irradiated in the VVR-S reactor at a 10/sup 9/ neutrons/cm/sup 2/s thermal neutron flux. A gas filled FEC (GAFFC) has been devised and tested in the reactor at the same neutron flux. With this GAFEC U /SUB oc/ of hundreds of kV, J /SUB sc/ of hundreds of ..mu..A and powers of hundreds of mW have been obtained. Our researches pointed out the essential part played by the electrons in the charge transport dynamics occuring in the FEC and the influence of the secondary emission on the FEC operation.

Ursu, I.; Badescu-Singureann, A.I.; Schachter, L.

1983-08-01T23:59:59.000Z

369

Engineering Report on the Fission Gas Getter Concept  

SciTech Connect (OSTI)

In 2010, the Department of Energy (DOE) requested that a Brookhaven National Laboratory (BNL)-led team research the possibility of using a getter material to reduce the pressure in the plenum region of a light water reactor fuel rod. During the first two years of the project, several candidate materials were identified and tested using a variety of experimental techniques, most with xenon as a simulant for fission products. Earlier promising results for candidate getter materials were found to be incorrect, caused by poor experimental techniques. In May 2012, it had become clear that none of the initial materials had demonstrated the ability to adsorb xenon in the quantities and under the conditions needed. Moreover, the proposed corrective action plan could not meet the schedule needed by the project manager. BNL initiated an internal project review which examined three questions: 1. Which materials, based on accepted materials models, might be capable of absorbing xenon? 2. Which experimental techniques are capable of not only detecting if xenon has been absorbed but also determine by what mechanism and the resulting molecular structure? 3. Are the results from the previous techniques useable now and in the future? As part of the second question, the project review team evaluated the previous experimental technique to determine why incorrect results were reported in early 2012. This engineering report is a summary of the current status of the project review, description of newly recommended experiments and results from feasibility studies at the National Synchrotron Light Source (NSLS).

Ecker, Lynne; Ghose, Sanjit; Gill, Simerjeet; Thallapally, Praveen K.; Strachan, Denis M.

2012-11-01T23:59:59.000Z

370

Fusion materials irradiations at MaRIE's fission fusion facility  

SciTech Connect (OSTI)

Los Alamos National Laboratory's proposed signature facility, MaRIE, will provide scientists and engineers with new capabilities for modeling, synthesizing, examining, and testing materials of the future that will enhance the USA's energy security and national security. In the area of fusion power, the development of new structural alloys with better tolerance to the harsh radiation environments expected in fusion reactors will lead to improved safety and lower operating costs. The Fission and Fusion Materials Facility (F{sup 3}), one of three pillars of the proposed MaRIE facility, will offer researchers unprecedented access to a neutron radiation environment so that the effects of radiation damage on materials can be measured in-situ, during irradiation. The calculated radiation damage conditions within the F{sup 3} match, in many respects, that of a fusion reactor first wall, making it well suited for testing fusion materials. Here we report in particular on two important characteristics of the radiation environment with relevancy to radiation damage: the primary knock-on atom spectrum and the impact of the pulse structure of the proton beam on temporal characteristics of the atomic displacement rate. With respect to both of these, analyses show the F{sup 3} has conditions that are consistent with those of a steady-state fusion reactor first wall.

Pitcher, Eric J [Los Alamos National Laboratory

2010-10-06T23:59:59.000Z

371

Supply Chain The effective supply chain has become a new organizational and operational  

E-Print Network [OSTI]

MBA in Supply Chain Management #12;The effective supply chain has become a new organizational a virtual integration of business partners to achieve new levels of efficiency and productivity, as well

Lin, Xiaodong

372

Reactor for exothermic reactions  

DOE Patents [OSTI]

A liquid phase process for oligomerization of C.sub.4 and C.sub.5 isoolefins or the etherification thereof with C.sub.1 to C.sub.6 alcohols wherein the reactants are contacted in a reactor with a fixed bed acid cation exchange resin catalyst at an LHSV of 5 to 20, pressure of 0 to 400 psig and temperature of 120.degree. to 300.degree. F. Wherein the improvement is the operation of the reactor at a pressure to maintain the reaction mixture at its boiling point whereby at least a portion but less than all of the reaction mixture is vaporized. By operating at the boiling point and allowing a portion of the reaction mixture to vaporize, the exothermic heat of reaction is dissipated by the formation of more boil up and the temperature in the reactor is controlled.

Smith, Jr., Lawrence A. (Bellaire, TX); Hearn, Dennis (Houston, TX); Jones, Jr., Edward M. (Friendswood, TX)

1993-01-01T23:59:59.000Z

373

Reactor for exothermic reactions  

DOE Patents [OSTI]

A liquid phase process is described for oligomerization of C[sub 4] and C[sub 5] isoolefins or the etherification thereof with C[sub 1] to C[sub 6] alcohols wherein the reactants are contacted in a reactor with a fixed bed acid cation exchange resin catalyst at an LHSV of 5 to 20, pressure of 0 to 400 psig and temperature of 120 to 300 F. Wherein the improvement is the operation of the reactor at a pressure to maintain the reaction mixture at its boiling point whereby at least a portion but less than all of the reaction mixture is vaporized. By operating at the boiling point and allowing a portion of the reaction mixture to vaporize, the exothermic heat of reaction is dissipated by the formation of more boil up and the temperature in the reactor is controlled.

Smith, L.A. Jr.; Hearn, D.; Jones, E.M. Jr.

1993-03-02T23:59:59.000Z

374

Introduction The Sustainable Supply Chain Taxes Permits Integration Future Research Sustainable Supply Chains  

E-Print Network [OSTI]

Introduction The Sustainable Supply Chain Taxes Permits Integration Future Research Sustainable;Introduction The Sustainable Supply Chain Taxes Permits Integration Future Research 1 Introduction 2 The Sustainable Supply Chain 3 Taxes 4 Permits 5 Integration 6 Future Research Dissertation Defense by Trisha D

Nagurney, Anna

375

P-odd, P-even, and T-odd asymmetries in true quaternary fission of nuclei  

SciTech Connect (OSTI)

The coefficients of P-odd, P-even, and T -odd asymmetries for a third and a fourth prescission particle emitted in the true quaternary fission of nuclei that was induced by polarized cold neutrons were studied on the basis of quantum-mechanical fission theory. By using non-evaporation (nonadiabatic) mechanisms of light-particle emission, these coefficients were compared with the analogous coefficients for prescission third particles emitted in the ternary fission of nuclei.

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Titova, L. V. [Voronezh State University (Russian Federation)] [Voronezh State University (Russian Federation)

2013-04-15T23:59:59.000Z

376

A Review of Previous Research in Direct Energy Conversion Fission Reactors  

SciTech Connect (OSTI)

From the earliest days of power reactor development, direct energy conversion was an obvious choice to produce high efficiency electric power generation. Directly capturing the energy of the fission fragments produced during nuclear fission avoids the intermediate conversion to thermal energy and the efficiency limitations of classical thermodynamics. Efficiencies of more than 80% are possible, independent of operational temperature. Direct energy conversion fission reactors would possess a number of unique characteristics that would make them very attractive for commercial power generation. These reactors would be modular in design with integral power conversion and operate at low pressures and temperatures. They would operate at high efficiency and produce power well suited for long distance transmission. They would feature large safety margins and passively safe design. Ideally suited to production by advanced manufacturing techniques, direct energy conversion fission reactors could be produced more economically than conventional reactor designs. The history of direct energy conversion can be considered as dating back to 1913 when Moseleyl demonstrated that charged particle emission could be used to buildup a voltage. Soon after the successful operation of a nuclear reactor, E.P. Wigner suggested the use of fission fragments for direct energy conversion. Over a decade after Wigner's suggestion, the first theoretical treatment of the conversion of fission fragment kinetic energy into electrical potential appeared in the literature. Over the ten years that followed, a number of researchers investigated various aspects of fission fragment direct energy conversion. Experiments were performed that validated the basic physics of the concept, but a variety of technical challenges limited the efficiencies that were achieved. Most research in direct energy conversion ceased in the US by the late 1960s. Sporadic interest in the concept appears in the literature until this day, but there have been no recent significant programs to develop the technology.

DUONG,HENRY; POLANSKY,GARY F.; SANDERS,THOMAS L.; SIEGEL,MALCOLM D.

1999-09-22T23:59:59.000Z

377

DIRECT ENERGY CONVERSION (DEC) FISSION REACTORS - A U.S. NERI PROJECT  

SciTech Connect (OSTI)

The direct conversion of the electrical energy of charged fission fragments was examined early in the nuclear reactor era, and the first theoretical treatment appeared in the literature in 1957. Most of the experiments conducted during the next ten years to investigate fission fragment direct energy conversion (DEC) were for understanding the nature and control of the charged particles. These experiments verified fundamental physics and identified a number of specific problem areas, but also demonstrated a number of technical challenges that limited DEC performance. Because DEC was insufficient for practical applications, by the late 1960s most R&D ceased in the US. Sporadic interest in the concept appears in the literature until this day, but there have been no recent programs to develop the technology. This has changed with the Nuclear Energy Research Initiative that was funded by the U.S. Congress in 1999. Most of the previous concepts were based on a fission electric cell known as a triode, where a central cathode is coated with a thin layer of nuclear fuel. A fission fragment that leaves the cathode with high kinetic energy and a large positive charge is decelerated as it approaches the anode by a charge differential of several million volts, it then deposits its charge in the anode after its kinetic energy is exhausted. Large numbers of low energy electrons leave the cathode with each fission fragment; they are suppressed by negatively biased on grid wires or by magnetic fields. Other concepts include magnetic collimators and quasi-direct magnetohydrodynamic generation (steady flow or pulsed). We present the basic principles of DEC fission reactors, review the previous research, discuss problem areas in detail and identify technological developments of the last 30 years relevant to overcoming these obstacles. A prognosis for future development of direct energy conversion fission reactors will be presented.

D. BELLER; G. POLANSKY; ET AL

2000-11-01T23:59:59.000Z

378

Evaluation of fission product worth margins in PWR spent nuclear fuel burnup credit calculations.  

SciTech Connect (OSTI)

Current criticality safety calculations for the transportation of irradiated LWR fuel make the very conservative assumption that the fuel is fresh. This results in a very substantial overprediction of the actual k{sub eff} of the transportation casks; in certain cases, this decreases the amount of spent fuel which can be loaded in a cask, and increases the cost of transporting the spent fuel to the repository. Accounting for the change of reactivity due to fuel depletion is usually referred to as ''burnup credit.'' The US DOE is currently funding a program aimed at establishing an actinide only burnup credit methodology (in this case, the calculated reactivity takes into account the buildup or depletion of a limited number of actinides). This work is undergoing NRC review. While this methodology is being validated on a significant experimental basis, it implicitly relies on additional margins: in particular, the absorption of neutrons by certain actinides and by all fission products is not taken into account. This provides an important additional margin and helps guarantee that the methodology is conservative provided these neglected absorption are known with reasonable accuracy. This report establishes the accuracy of fission product absorption rate calculations: (1) the analysis of European fission product worth experiments demonstrates that fission product cross-sections available in the US provide very good predictions of fission product worth; (2) this is confirmed by a direct comparison of European and US cross section evaluations; (3) accuracy of Spent Nuclear Fuel (SNF) fission product content predictions is established in a recent ORNL report where several SNF isotopic assays are analyzed; and (4) these data are then combined to establish in a conservative manner the fraction of the predicted total fission product absorption which can be guaranteed based on available experimental data.

Blomquist, R.N.; Finck, P.J.; Jammes, C.; Stenberg, C.G.

1999-02-17T23:59:59.000Z

379

Description of Induced Nuclear Fission with Skyrme Energy Functionals: II. Finite Temperature Effects  

E-Print Network [OSTI]

Understanding the mechanisms of induced nuclear fission for a broad range of neutron energies could help resolve fundamental science issues, such as the formation of elements in the universe, but could have also a large impact on societal applications in energy production of nuclear waste management. The goal of this paper is to set up the foundations of a microscopic model to study the static aspects of induced fission as a function of the excitation energy of the incident neutron, from thermal to fast neutrons. To account for the high excitation energy of the compound nucleus, we employ a statistical approach based on finite temperature nuclear density functional theory with Skyrme energy densities, which we benchmark on the fission of 239Pu(n,f). We compute the evolution of the least-energy fission pathway across multidimensional potential energy surfaces with up to five collective variables as a function of the nuclear temperature, and predict the evolution of both the inner and outer fission barriers as a function of the excitation energy of the compound nucleus. We show that the coupling to the continuum induced by the finite temperature is negligible in the range of neutron energies relevant to induced fission. We prove that the concept of quantum localization introduced recently can be extended to T>0, and we apply the method to compute the kinetic and interaction energy of fission fragments as a function of the temperature. While large uncertainties in theoretical modeling remain, we conclude that finite temperature nuclear density functional may provide a useful framework to obtain accurate predictions.

N. Schunck; D. Duke; H. Carr

2014-02-21T23:59:59.000Z

380

Supply Chain Networks: Challenges and Opportunities  

E-Print Network [OSTI]

School of Management University of Massachusetts Amherst, Massachusetts 01003 Department of Management, and consumers at the demand markets. Today, supply chains may span thousands of miles across the globe, involve as the stability and resiliency of supply chains, as well as their adaptability and responsiveness to events

Nagurney, Anna

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Supply Chain Networks: Challenges and Opportunities  

E-Print Network [OSTI]

School of Management University of Massachusetts Amherst, Massachusetts 01003 Boston INFORMS Chapter and suppliers, distributors, retailers, and consumers at the demand markets. Today, supply chains may span chains, as well as their adaptability and responsiveness to events in a global environment of increasing

Nagurney, Anna

382

Supply Chain Networks: Challenges and Opportunities  

E-Print Network [OSTI]

School of Management University of Massachusetts Amherst, Massachusetts 01003 International Conference of manufacturers and suppliers, distributors, retailers, and consumers at the demand markets. Today, supply chains chains, as well as their adaptability and responsiveness to events in a global environment of increasing

Nagurney, Anna

383

Supply Chains and Transportation Networks Anna Nagurney  

E-Print Network [OSTI]

Management Isenberg School of Management University of Massachusetts Amherst, Massachusetts 01003 December, and consumers at the demand markets. Supply chains are the backbones of our globalized Network Economy of cooperation. For example, in a vertically integrated supply chain the same firm may be responsible

Nagurney, Anna

384

Internal Markets for Supply Chain Capacity Allocation  

E-Print Network [OSTI]

Internal Markets for Supply Chain Capacity Allocation David McAdams and Thomas W. Malone Sloan David McAdams & Thomas Malone #12;Internal Markets for Supply Chain Capacity Allocation David Mc ("internal markets") to help allocate manufacturing capacity and determine the prices, delivery dates

385

The XY Spin Chain Random Block Operators  

E-Print Network [OSTI]

The XY Spin Chain Random Block Operators Proof of Main Result Open Questions Localization for Random Block Operators Related to the XY Spin Chain Jacob W. Chapman Division of Science Southern Wesleyan University Central, SC Joint work with G¨unter Stolz UAB NSF-CBMS Conference on Quantum Spin

Jung, Paul

386

Energy Balanced Chain in Distributed Sensor Networks  

E-Print Network [OSTI]

Energy Balanced Chain in Distributed Sensor Networks Ivan Howitt Electrical & Computer Engineering because of their higher traffic. This paper suggests an energy balanced chain (EBC) which can efficiently the energy balance optimization problem in terms of the segmentation space. By adjusting the transmission

Howitt, Ivan

387

Test of the adequacy of using smoothly joined parabolic segments to parametrize the multihumped fission barriers in actinides  

SciTech Connect (OSTI)

The adequacy of using smoothly joined parabolic segments to parametrize the multihumped fission barriers has been tested by examining its simultaneous consistency with the three relevant fission observables, namely, the near-barrier fission cross sections, isomeric half-lives, and the ground-state spontaneous fission half-lives of a wide variety of a total of 25 actinide nuclides. The penetrabilities through such multihumped fission barriers have been calculated in the Wentzel-Kramers-Brillouin approximation, and the various fission half-lives have been determined using the formalism given earlier by Nix and Walker. The results of our systematic analysis of these actinide nuclides suggest that such a parametrization is quite adequate at least for the even-even nuclei, as it reproduces satisfactorily their various observed fission characteristics. Major difficulties remain, however, for the odd mass and for the doubly odd nuclei where the calculated ground-state spontaneous fission half-lives are found to be several orders of magnitude larger than those measured. Possible reasons for such discrepancies are discussed. Fission branching ratios of the decay of the shape isomers in various actinide nuclides have also been calculated and are compared with their measured values.

Bhandari, B.S. (Department of Physics, Faculty of Science, University of Garyounis, Benghazi (Libya))

1990-10-01T23:59:59.000Z

388

Laser Inertial Fusion-based Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System  

E-Print Network [OSTI]

of Con- trolled Nuclear Fusion, CONF-760975-P3, pages 1061–more effective solution, nuclear fusion. Fission Energy Thethe development of nuclear fusion weapons, humankind has

Kramer, Kevin James

2010-01-01T23:59:59.000Z

389

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD DECEMBER 1,1999 THRIUGH FEBRUARY 29,2000  

SciTech Connect (OSTI)

OAK-B135 DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD DECEMBER 1,1999 THRIUGH FEBRUARY 29,2000

LC BROWN

2000-02-29T23:59:59.000Z

390

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD OCTOBER 1,2001 THROUGH DECEMBER 31,2001  

SciTech Connect (OSTI)

OAK-B135 DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD OCTOBER 1,2001 THROUGH DECEMBER 31,2001

L.C. BROWN

2001-12-31T23:59:59.000Z

391

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD DECEMBER 1,2000 THROUGH FEBRUARY 28,2001  

SciTech Connect (OSTI)

OAK-B135 DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD DECEMBER 1,2000 THROUGH FEBRUARY 28,2001

L.C. BROWN

2000-02-28T23:59:59.000Z

392

DIRECT ENERGY CONVERSION FISSION REACTOR ANNUAL REPORT FOR THE PERIOD AUGUST 15,2000 THROUGH SEPTEMBER 30,2001  

SciTech Connect (OSTI)

OAK-B135 DIRECT ENERGY CONVERSION FISSION REACTOR ANNUAL REPORT FOR THE PERIOD AUGUST 15,2000 THROUGH SEPTEMBER 30,2001

L.C. BROWN

2002-02-01T23:59:59.000Z

393

DIRECT ENERGY CONVERSION FISSION REACTOR ANNUAL REPORT FOR THE PERIOD OCTOBER 1, 2001 THROUGH DECEMBER 31, 2002  

SciTech Connect (OSTI)

OAK-B135 DIRECT ENERGY CONVERSION FISSION REACTOR ANNUAL REPORT FOR THE PERIOD OCTOBER 1, 2001 THROUGH DECEMBER 31, 2002

L.C. BROWN

2003-04-07T23:59:59.000Z

394

Singlet-Fission Sensitizers for Ultra-High Efficiency Excitonic Solar Cells: 15 August 2005 - 14 October 2008  

SciTech Connect (OSTI)

We have considered the potential benefits offered by using singlet fission sensitizers in photovoltaic cells and identified two key issues involved in the search for such sensitizers.

Michl, J.

2008-12-01T23:59:59.000Z

395

Laser Inertial Fusion-based Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System  

E-Print Network [OSTI]

DT Deuterium-Tritium DU Depleted Uranium FIMA Fission ofengine loaded with depleted uranium. In Proc. PHYSOR 2010,fuel layer comprised of depleted uranium contained in

Kramer, Kevin James

2010-01-01T23:59:59.000Z

396

Single-Chain Antibody Library  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Researchers at Pacific Northwest National Laboratory (PNNL) have constructed a nonimmune library consisting of 109 human antibody scFv fragments, which have been cloned and expressed on the surface of yeast. Nanomolar-affinity scFvs are routinely obtained by magnetic bead screening and flow cytometric sorting. The yeast library can be amplified 1010 fold without measurable loss of clonal diversity. This allows for indefinite expansion of the library. All scFv clones can be assessed directly on the yeast cell surface by immunofluorescent labeling and flow cytometry, obviating separate subcloning, expression, and purification steps. The ability to use multiplex library screening demonstrates the utility of this approach for high-throughput antibody isolation for proteomic applications. The yeast library may be used for research projects or teaching performed for U.S. Government purposes only. If you would like to request an aliquot of the single-chain antibody library for your research, please print and fill out the Materials Transfer Agreement (MTA) [PDF, 20K]. The website provides the contact information for mailing the MTA. [copied from http://www.sysbio.org/dataresources/singlechain.stm

Baird, Cheryl

397

Reaction network and kinetics for the catalytic oxidation of toluene over V sub 2 O sub 5  

SciTech Connect (OSTI)

The oxidation of three methyl-diphenylmethane isomers and of bibenzyl, benzyl alcohol, and benzaldehyde, which are intermediates in the catalytic oxidation of toluene over V{sub 2}O{sub 5}, has been studied to elucidate the reaction network and relative importance of various reactions. Selectivity dependences reveal that the network is composed mainly of three parallel reaction routes: (1) side-chain oxidation with consecutive reactions, (2) oxidative coupling with both parallel and consecutive reactions, and (3) carbon oxide formation. Coupling products are not negligible, with an initial selectivity of 29% (400{degree}C). Anthraquinone is produced mainly from o-methyl-diphenylmethane conditions and catalyst used. Selectivity dependences suggested product lumping and a simplified network. Kinetic analysis of this reaction network indicates that higher temperatures favor route 2 over route 1. The same initial intermediates for route 1 of side-chain oxidation and for route 2 of oxidative coupling are suggested.

Zhu, J.; Andersson, L.T. (Univ. of Lund (Sweden))

1990-11-01T23:59:59.000Z

398

Fission-product-release signatures for LWR fuel rods failed during PCM and RIA transients  

SciTech Connect (OSTI)

This paper discusses fission product release from light-water-reactor-type fuel rods to the coolant loop during design basis accident tests. One of the tests was a power-cooling-mismatch test in which a single fuel rod was operated in film boiling beyond failure. Other tests discussed include reactivity initiated accident (RIA) tests, in which the fuel rods failed as a result of power bursts that produced radial-average peak fuel enthalpies ranging from 250 to 350 cal/g. One of the RIA tests used two previously irradiated fuel rods. On-line gamma spectroscopic measurements of short-lived fission products, and important aspects of fission product behavior observed during the tests, are discussed. Time-dependent release fractions for short-lived fission products are compared with release fractions suggested by: the Reactor Safety Study; NRC Regulatory Guides; and measurements from the Three Mile Island accident. Iodine behavior observed during the tests is discussed, and fuel powdering is identified as a source of particulate fission product activity, the latter of which is neglected for most accident analyses.

Osetek, D.J.; King, J.J.; Croucher, D.W.

1981-01-01T23:59:59.000Z

399

Fission matrix-based Monte Carlo criticality analysis of fuel storage pools  

SciTech Connect (OSTI)

Standard Monte Carlo transport procedures experience difficulties in solving criticality problems in fuel storage pools. Because of the strong neutron absorption between fuel assemblies, source convergence can be very slow, leading to incorrect estimates of the eigenvalue and the eigenfunction. This study examines an alternative fission matrix-based Monte Carlo transport method that takes advantage of the geometry of a storage pool to overcome this difficulty. The method uses Monte Carlo transport to build (essentially) a fission matrix, which is then used to calculate the criticality and the critical flux. This method was tested using a test code on a simple problem containing 8 assemblies in a square pool. The standard Monte Carlo method gave the expected eigenfunction in 5 cases out of 10, while the fission matrix method gave the expected eigenfunction in all 10 cases. In addition, the fission matrix method provides an estimate of the error in the eigenvalue and the eigenfunction, and it allows the user to control this error by running an adequate number of cycles. Because of these advantages, the fission matrix method yields a higher confidence in the results than standard Monte Carlo. We also discuss potential improvements of the method, including the potential for variance reduction techniques. (authors)

Farlotti, M. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Ecole Polytechnique, Palaiseau, F 91128 (France); Larsen, E. W. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

2013-07-01T23:59:59.000Z

400

Fission Yield Measurements from Highly Enriched Uranium Irradiated Inside a Boron Carbide Capsule  

SciTech Connect (OSTI)

A boron carbide capsule was previously designed and tested by Pacific Northwest National Laboratory (PNNL) and Washington State University (WSU) for spectral-tailoring in mixed spectrum reactors. The presented work used this B4C capsule to create a fission product sample from the irradiation of highly enriched uranium (HEU) with a fast fission neutron spectrum. An HEU foil was irradiated inside of the capsule in WSU’s 1 MW TRIGA reactor at full power for 200 min to produce 5.8 × 1013 fissions. After three days of cooling, the sample was shipped to PNNL for radiochemical separations and analysis by gamma and beta spectroscopy. Fission yields for products were calculated from the radiometric measurements and compared to measurements from thermal neutron induced fission (analyzed in parallel with the non-thermal sample at PNNL) and published evaluated fast-pooled and thermal nuclear data. Reactor dosimetry measurements were also completed to fully characterize the neutron spectrum and total fluence of the irradiation.

Metz, Lori A.; Friese, Judah I.; Finn, Erin C.; Greenwood, Lawrence R.; Kephart, Rosara F.; Hines, Corey C.; King, Matthew D.; Henry, Kelley; Wall, Donald E.

2013-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JANUARY 1, 2002 THROUGH MARCH 31, 2002  

SciTech Connect (OSTI)

Direct energy conversion is the only potential means for producing electrical energy from a fission reactor without the Carnot efficiency limitations. This project was undertaken by Sandia National Laboratories, Los Alamos National Laboratories, The University of Florida, Texas A&M University and General Atomics to explore the possibilities of direct energy conversion. Other means of producing electrical energy from a fission reactor, without any moving parts, are also within the statement of proposed work. This report documents the efforts of General Atomics. Sandia National Laboratories, the lead laboratory, provides overall project reporting and documentation. The highlights of this reporting period are: (1) Cooling of the vapor core reactor and the MHD generator was incorporated into the Vapor Core Reactor model using standard heat transfer calculation methods. (2) Fission product removal, previously modeled as independent systems for each class of fission product, was incorporated into the overall fuel recycle loop of the Vapor Core Reactor. The model showed that the circulating activity levels are quite low. (3) Material distribution calculations were made for the ''pom-pom'' style cathode for the Fission Electric Cell. Use of a pom-pom cathode will eliminate the problem of hoop stress in the thin spherical cathode caused by the electric field.

L.C. BROWN

2002-03-31T23:59:59.000Z

402

New features in the stability and fission decay of superheavy Thorium isotopes  

E-Print Network [OSTI]

Superheavy isotopes are highly neutron rich nuclei in the vicinity of neutron drip-line, stabilized by shell effect against the instability due to repulsive component of nuclear force, analogous to superheavy elements similarly stabilized against Coulomb instability. Here we discuss the stability and fission decay properties of such nuclei in the $^{254}$Th region and show that they are stable against $\\alpha$ and fission decay and have $\\beta$-decay life time of several tens of seconds. In particular, the $^{254}$Th nucleus has a low fission barrier and unusally large barrier width. This makes it an ideal thermally fissile nucleus, if formed by means of a thermal neutron, like other known nuclei such as $^{233}$U, $^{235}$U, $^{239}$Pu in this actinide region. It shows a new mode of fast fission decay, which may be termed as multifragmentation fission, in which in addition to two heavy fragments large number of scission neutrons are simultaneously produced. Its likely synthesis during the r-process nucleosynthesis will have important bearing on steller evolution, and here in the laboratory, it has great potential in energy production.

L. Satpathy; S. K. Patra; R. K. Choudhury

2006-04-12T23:59:59.000Z

403

Method of Fission Product Beta Spectra Measurements for Predicting Reactor Anti-neutrino Emission  

E-Print Network [OSTI]

The nuclear fission process that occurs in the core of nuclear reactors results in unstable, neutron rich fission products that subsequently beta decay and emit electron anti-neutrinos. These reactor neutrinos have served neutrino physics research from the initial discovery of the neutrino to current precision measurements of neutrino mixing angles. The prediction of the absolute flux and energy spectrum of the emitted reactor neutrinos hinges upon a series of seminal papers based on measurements performed in the 1970s and 1980s. The steadily improving reactor neutrino measurement techniques and recent re-considerations of the agreement between the predicted and observed reactor neutrino flux motivates revisiting the underlying beta spectra measurements. A method is proposed to use an accelerator proton beam delivered to an engineered target to yield a neutron field tailored to reproduce the neutron energy spectrum present in the core of an operating nuclear reactor. Foils of the primary reactor fissionable isotopes placed in this tailored neutron flux will ultimately emit beta particles from the resultant fission products. Measurement of these beta particles in a time projection chamber with a perpendicular magnetic field provides a distinctive set of systematic considerations for comparison to the original seminal beta spectra measurements. Ancillary measurements such as gamma-ray emission and post-irradiation radiochemical analysis will further constrain the absolute normalization of beta emissions per fission. The requirements for unfolding the beta spectra measured with this method into a predicted reactor neutrino spectrum are explored.

D. M. Asner; K. Burns; L. W. Campbell; B. Greenfield; M. S. Kos; J. L. Orrell; M. Schram; B. VanDevender; 1 L. S. Wood; D. W. Wootan

2014-03-01T23:59:59.000Z

404

Quantum spin chains and random matrix theory  

E-Print Network [OSTI]

The spectral statistics and entanglement within the eigenstates of generic spin chain Hamiltonians are analysed. A class of random matrix ensembles is defined which include the most general nearest-neighbour qubit chain Hamiltonians. For these ensembles, and their generalisations, it is seen that the long chain limiting spectral density is a Gaussian and that this convergence holds on the level of individual Hamiltonians. The rate of this convergence is numerically seen to be slow. Higher eigenvalue correlation statistics are also considered, the canonical nearest-neighbour level spacing statistics being numerically observed and linked with ensemble symmetries. A heuristic argument is given for a conjectured form of the full joint probability density function for the eigenvalues of a wide class of such ensembles. This is numerically verified in a particular case. For many translationally-invariant nearest-neighbour qubit Hamiltonians it is shown that there exists a complete orthonormal set of eigenstates for which the entanglement present in a generic member, between a fixed length block of qubits and the rest of the chain, approaches its maximal value as the chain length increases. Many such Hamiltonians are seen to exhibit a simple spectrum so that their eigenstates are unique up to phase. The entanglement within the eigenstates contrasts the spectral density for such Hamiltonians, which is that seen for a non-interacting chain of qubits. For such non-interacting chains, their always exists a basis of eigenstates for which there is no entanglement present.

Huw J Wells

2014-10-07T23:59:59.000Z

405

Velocity pump reaction turbine  

DOE Patents [OSTI]

An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

House, Palmer A. (Walnut Creek, CA)

1982-01-01T23:59:59.000Z

406

Velocity pump reaction turbine  

DOE Patents [OSTI]

An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

House, Palmer A. (Walnut Creek, CA)

1984-01-01T23:59:59.000Z

407

Some Reactions of Formamidines  

E-Print Network [OSTI]

.1028 x .01401 « 11.36 % H. HC«H*0CH«CeH5 Theoretical for HC ' or C 3 4H 2 70 9H5 N HECeH*OCH*CeHs H = 70.05 v 10.99 $ nitrogen found - H.36 $ 19 Preparation of oyanaoetio derivatives of di-p~benzyl-oxy-di-phenyl- formamidin©. Heat molecular... as hydrochloride b.- Piorates o.- Chloroplatinates. 2.- Reaction with compounds containing methylene hydrogen. a.- Reaction of oyanacetio ethyl ester with a substi­ tuted formamidine. OH OH I R I CHa * HO = 0 * HCHH R ^ R M a I * HER I COOCaHs COOCa...

Malleis, Otto Oscar

1913-05-15T23:59:59.000Z

408

Magnetic Field Generation in Planets and Satellites by Natural Nuclear Fission Reactors  

E-Print Network [OSTI]

One of the most fundamental problems in physics has been to understand the nature of the mechanism that generates the geomagnetic field and the magnetic fields of other planets and satellites. For decades, the dynamo mechanism, thought to be responsible for generating the geomagnetic field and other planetary magnetic fields, has been ascribed to convection in each planet's iron-alloy core. Recently, I described the problems inherent in Earth-core convection and proposed instead that the geomagnetic field is produced by a dynamo mechanism involving convection, not in the fluid core, but in the electrically conductive, fluid, fission-product sub-shell of a natural nuclear fission reactor at the center of the Earth, called the georeactor. Here I set forth in detail the commonality in the Solar System of the matter like that of the inside of the Earth, which is my basis for generalizing the concept of planetary magnetic field generation by natural planetocentric nuclear fission reactors.

J. Marvin Herndon

2007-09-27T23:59:59.000Z

409

Delayed neutron noise characteristics of an in-pile fission product loop  

SciTech Connect (OSTI)

This paper reports on delayed neutron noise measurements carried out in an in-pile sodium loop, the Fission Product Loop 2 (FPL-2), installed on the Toshiba Training Reactor I. To clarify the characteristics and origin of delayed neutron count rate noise, a noise propagation mechanism was identified using a multivariate autoregressive model. The results show that a simulated fuel failure in the FPL-2, with recoil as the principal fission product release phenomena, produces a white spectrum of delayed neutron count rate noise. It was also found that the loop temperature fluctuation strongly affects the delayed neutron count rate noise at temperatures below 300{degrees} C, through the deposition of fission products on the surface of structures.

Tamaoki, T. (Toshiba Corp., Nuclear Engineering Lab., 8 Shin-Sugita, Isogo-ku, Yokohama 235 (JP)); Sakai, T.; Endo, H. (Toshiba Corp., Isogo Engineering Center, 8 Shin-Sugita, Isogo-ku, Yokohama 235 (JP)); Haga, K. (Power Reactor and Nuclear Fuel Development Corp., O-aral Engineering Center, 4002 Narita, O-araimachi, Ibaraki-ken 311-13 (JP)); Takahashi, R. (Tokyo Inst. of Technology, Dept. of Mechanical Engineering, Ookayama, Meguro-ku, Tokyo 152 (JP))

1992-07-01T23:59:59.000Z

410

Impact of demographics on supply chain risk management practices  

E-Print Network [OSTI]

Do demographic factors play a role in the choice of supply chain risk management practices by supply chain professionals? Are there stronger relationships between certain demographic factors and supply chain risk management ...

Kanyagui, Kenneth (Kenneth K.)

2010-01-01T23:59:59.000Z

411

Criticality without Frustration for Quantum Spin-1 Chains  

E-Print Network [OSTI]

Frustration-free (FF) spin chains have a property that their ground state minimizes all individual terms in the chain Hamiltonian. We ask how entangled the ground state of a FF quantum spin-s chain with nearest-neighbor ...

Movassagh, Ramis

412

Dynamic Electric Power Supply Chains and Transportation Networks  

E-Print Network [OSTI]

Dynamic Electric Power Supply Chains and Transportation Networks: an Evolutionary Variational energy Electric power supply chains, provide the foundations for theElectric power supply chains, provide and societies. Communication, transportation, heating, lighting, cooling,Communication, transportation, heating

Nagurney, Anna

413

An engineering approach to improving hospital supply chains  

E-Print Network [OSTI]

This thesis explores supply chain management practices that have been implemented, and have improved supply chains in industries outside of healthcare. The presented supply chain practices have been selected because they ...

Cheng, Scott Hsiang-Jen

2008-01-01T23:59:59.000Z

414

Reaction product imaging  

SciTech Connect (OSTI)

Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

Chandler, D.W. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01T23:59:59.000Z

415

Post-irradiation Examination and Fission Product Inventory Analysis of AGR-1 Irradiation Capsules  

SciTech Connect (OSTI)

The AGR-1 experiment was the first in a series of Advanced Gas Reactor (AGR) experiments designed to test TRISO fuel under High Temperature Gas Reactor irradiation conditions. This experiment was irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) and is currently undergoing post-irradiation examination (PIE) at INL’s Materials and Fuels Complex (MFC). The inventory and distribution of fission products, especially Ag-110m, was assessed and analyzed for all the components of the AGR-1 capsules. This data should help inform the study of fission product migration in coated particle fuel. Gamma spectrometry was used to measure the activity of various different fission products in the different components of the AGR-1 test train. Each capsule contained: 12 fuel compacts, a graphite holder that kept the fuel compacts in place, graphite spacers that were above and below the graphite holders and fuel compacts, gas lines through which a helium neon gas mixture flowed in and out of each capsule, and the stainless steel shell that contained the experiment. Gamma spectrometry results and the experimental techniques used to capture these results will be presented for all the capsule components. The components were assayed to determine the total activity of different fission products present in or on them. These totals are compared to the total expected activity of a particular fission product in the capsule based on predictions from physics simulation. Based on this metric, a significant fraction of the Ag-110m was detected outside the fuel compacts, but the amount varied highly between the 6 capsules. Very small fractions of Cs-137 (<2E-5), Cs-134 (<1e-5), and Eu-154 (<4e-4) were detected outside of the fuel compacts. Additionally, the distribution of select fission products in some of the components including the fuel compacts and the graphite holders were measured and will be discussed.

J M Harp; P D Demkowicz; S A Ploger

2012-10-01T23:59:59.000Z

416

TRISO Fuel Performance: Modeling, Integration into Mainstream Design Studies, and Application to a Thorium-fueled Fusion-Fission Hybrid Blanket  

E-Print Network [OSTI]

of a Hybrid Fusion-Fission Nuclear Energy System. ” Thesis.hybrid fusion-fission Laser Inertial Fusion-based Energy (LIFE) systems.Hybrid LIFE Engines Laser Inertial Fusion-based Energy (LIFE) systems

Powers, Jeffrey

2011-01-01T23:59:59.000Z

417

November 9, 2003 21:47 WSPC/Trim Size: 9in x 6in for Proceedings royer-nanuf03 FISSION BARRIERS  

E-Print Network [OSTI]

Institute of Physics and Nuclear Engineering, P.O. Box MG-6, RO-76900, Bucharest, Romania E-mail: rgherg-fission of heavy systems and fragmentation have renewed interest in investigating the fusion-like fission valley

Paris-Sud XI, Université de

418

Probabilities for the emission of light particles and their energy and angular distributions for true quaternary nuclear fission  

SciTech Connect (OSTI)

On the basis of quantum-mechanical fission theory, the features of true quaternary nuclear fission are studied by treating this fission process as a sequence of three processes following one another in the course of time. The first two processes are the escape of the first and then the second of the two light particles emitted from the neck of a fissioning nucleus because of a nonadiabatic character of the collective deformation motion of this nucleus. Finally, the third process is the separation of the fissioning nucleus into two rather heavy fission fragments. The differences that arise in the emission probabilities and in the angular and energy distributions upon going over from the first emitted to the second emitted prescission third and fourth particles are analyzed by invoking experimental data on the spontaneous and thermalneutron-induced fission of nuclei, and it is shown that these differences are caused by the changes both in the geometric configuration of the fissioning nucleus and in the shell structure of its neck after the first prescission particle is emitted from it.

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Titova, L. V. [Voronezh State University (Russian Federation)] [Voronezh State University (Russian Federation)

2013-01-15T23:59:59.000Z

419

Physics -Particle and Nuclear Physics | Theory of Nuclear Fission Springer is part of Springer Science+Business Media  

E-Print Network [OSTI]

Physics - Particle and Nuclear Physics | Theory of Nuclear Fission © Springer is part of Springer Science+Business Media Theory of Nuclear Fission A Textbook Series: Lecture Notes in Physics, Vol. 838 v arious aspects of the nuclear f ission phenomenon discov ered by Hahn, Strassmann and Meitner

Pomorski, Krzysztof

420

The Fission Yeast Copper-sensing Transcription Factor Cuf1 Regulates the Copper Transporter Gene Expression through an  

E-Print Network [OSTI]

The Fission Yeast Copper-sensing Transcription Factor Cuf1 Regulates the Copper Transporter Gene of copper transport is essential for copper homeostasis and growth in yeast. Analysis of regulatory regions in the promoter of the ctr4 copper transporter gene in fission yeast Schizosaccharomyces pombe re- veals

Labbé, Simon

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Measurement of Prompt Fission Neutron Spectrum Using a Gamma Tagging Method E. Blain, A. Daskalakis, Y. Danon  

E-Print Network [OSTI]

uncertainties in these values can have significant impact on the uncertainty associated with reactor criticality correspond to up to a 4% uncertainty on keff for various systems including both fast and light water systems fission chamber which uses the energy deposited by fission fragments in a fill gas to determine

Danon, Yaron

422

Photoneutron reactions in astrophysics  

SciTech Connect (OSTI)

Among key problems in nuclear astrophysics, that of obtaining deeper insight into the mechanism of synthesis of chemical elements is of paramount importance. The majority of heavy elements existing in nature are produced in stars via radiative neutron capture in so-called s- and r processes, which are, respectively, slow and fast, in relation to competing ?{sup ?}-decay processes. At the same time, we know 35 neutron-deficient so-called bypassed p-nuclei that lie between {sup 74}Se and {sup 196}Hg and which cannot originate from the aforementioned s- and r-processes. Their production is possible in (?, n), (?, p), or (?, ?) photonuclear reactions. In view of this, data on photoneutron reactions play an important role in predicting and describing processes leading to the production of p-nuclei. Interest in determining cross sections for photoneutron reactions in the threshold energy region, which is of particular importance for astrophysics, has grown substantially in recent years. The use of modern sources of quasimonoenergetic photons obtained in processes of inverse Compton laser-radiation scattering on relativistic electronsmakes it possible to reveal rather interesting special features of respective cross sections, manifestations of pygmy E1 and M1 resonances, or the production of nuclei in isomeric states, on one hand, and to revisit the problem of systematic discrepancies between data on reaction cross sections from experiments of different types, on the other hand. Data obtained on the basis of our new experimental-theoretical approach to evaluating cross sections for partial photoneutron reactions are invoked in considering these problems.

Varlamov, V. V., E-mail: Varlamov@depni.sinp.msu.ru; Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.; Stopani, K. A. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2014-12-15T23:59:59.000Z

423

Critical temperature for the nuclear liquid-gas phase transition (from multifragmentation and fission)  

E-Print Network [OSTI]

Critical temperature Tc for the nuclear liquid-gas phase transition is stimated both from the multifragmentation and fission data. In the first case,the critical temperature is obtained by analysis of the IMF yields in p(8.1 GeV)+Au collisions within the statistical model of multifragmentation (SMM). In the second case, the experimental fission probability for excited 188Os is compared with the calculated one with Tc as a free parameter. It is concluded for both cases that the critical temperature is higher than 16 MeV.

V. A. Karnaukhov; H. Oeschler; A. Budzanowski; S. P. Avdeyev; A. S. Botvina; E. A. Cherepanov; W. Karcz; V. V. Kirakosyan; P. A. Rukoyatkin; I. Skwirczynska; E. Norbeck

2008-01-29T23:59:59.000Z

424

The effect of. beta. -delayed fission on the production of r-process chronometers  

SciTech Connect (OSTI)

The nuclear physics required for calculating the production ratios for the chronometric pairs {sup 235}U/{sup 232}Th and {sup 238}U/{sup 232}Th in the astrophysical r-process is considered in some detail. In particular, we calculate the nuclear structure of neutron-rich heavy elements to investigate the effects of beta-delayed fission and beta-delayed neutron emission during the beta decay from the r-process path to the actinide region. We find that previous estimates of the effects of beta-delayed fission on the production of these pairs has probably been overestimated. 11 refs., 1 fig.

Howard, W.M.; Meyer, B.S.

1989-08-30T23:59:59.000Z

425

Proposal for ENDF formats that describe emission of post-fission beta-delayed photons  

SciTech Connect (OSTI)

Fission of heavy nuclides is accompanied by the birth of neutron rich fragment nuclei born in highly excited states. Following emission of prompt neutrons and {gamma}-rays, these fragments are typically left with atomic numbers that are 3-4 units smaller than stable nuclei with the same mass number. As these nuclides undergo {beta} decay to reach stability, a large number of {gamma}-rays are emitted. Figure 1 illustrates some of the processes leading to emission of {beta} delayed photons. A variety of applications (most notably those concerned with the detection and identification of clandestine fissile material) would benefit from a clear description of the spectral and temporal evolution of these {gamma}-rays. This proposal describes formats for representing emission of delayed photons and is based on the analysis presented in. At the present time, no single evaluated data set exists that directly provides for the temporal evolution of {gamma} rays from the decay of the fission products. However, evaluated data sets containing all of the physical parameters required for such calculations have been prepared. These include estimates of the independent and cumulative fission yields of all fission products, branching ratios in the decay of ground and isomeric states, lifetimes of these states, and the spectra of {gamma} rays emitted in their decay. Sizeable uncertainties and possibly significant errors are likely present concerning the shortest-lived fission products. However, the high-energy {gamma}-ray spectra generated from some of these data sets have been shown to be in reasonable agreement with initial experiments designed specifically to test them under conditions likely to be of interest to interrogation of sea-going cargo containers. For clarity we emphasize that the relationship between delayed neutron emission and delayed photon emission is tenuous. Only a small fraction of fission fragments - typically those characterized by large decay Q values - undergo {beta}{sup -}n emission. However, essentially all fission fragment decays result in the emission of a few photons. Also, it would be impractical to accurately specify and measure energies of delayed neutrons. By contrast, most fission fragments have decay spectra known to sub-keV accuracy that are readily resolved with inexpensive field HpGe detectors.

Brown, D; Pruet, J; Hedstrom, G; Hall, J; Descalle, M

2004-09-15T23:59:59.000Z

426

From ground state to fission fragments: A complex, multi-dimensional multi-path problem  

SciTech Connect (OSTI)

Experimental results on the fission properties of nuclei close to {sup 264}Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus {sup 258}Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic-energy distribution peaked at about 235 MeV whereas {sup 256}Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic-energy distribution peaked at about 200 MeV. Qualitatively, these sudden changes have been postulated to be due to the emergence of fragment shells in symmetric-fission products close to {sup 132}Sn. Here we present a quantitative calculation that shows where high-kinetic-energy symmetric fusion occurs and why it is associated with a sudden and large decrease in fission half-lives. We base our study on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. We use the three-quadratic-surface parameterization to generate the shapes for which the potential-energy surfaces are calculated. The use of this parameterization and the use of the finite-range macroscopic model allows for the study of two touching spheres and similar shapes. Since these shapes are thought to correspond to the scission shapes for the high-kinetic-energy events it is of crucial importance that a continuous sequence of shapes leading from the nuclear ground state to these configurations can be studied within the framework of the model. We present the results of the calculations in terms of potential-energy surfaces and fission half-lives for heavy even nuclei. The surfaces are displayed in the form of contour diagrams as functions of two moments of the shape. They clearly show the appearance of a second fission valley, which leads to scission configurations close to tow touching spheres, for fissioning systems in the vicinity of {sup 264}Fm.

Moeller, P. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)); Nix, J.R. (Los Alamos National Lab., NM (United States)); Swiatecki, W.J. (Lawrence Berkeley Lab., CA (United States))

1992-01-01T23:59:59.000Z

427

From ground state to fission fragments: A complex, multi-dimensional multi-path problem  

SciTech Connect (OSTI)

Experimental results on the fission properties of nuclei close to {sup 264}Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus {sup 258}Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic-energy distribution peaked at about 235 MeV whereas {sup 256}Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic-energy distribution peaked at about 200 MeV. Qualitatively, these sudden changes have been postulated to be due to the emergence of fragment shells in symmetric-fission products close to {sup 132}Sn. Here we present a quantitative calculation that shows where high-kinetic-energy symmetric fusion occurs and why it is associated with a sudden and large decrease in fission half-lives. We base our study on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. We use the three-quadratic-surface parameterization to generate the shapes for which the potential-energy surfaces are calculated. The use of this parameterization and the use of the finite-range macroscopic model allows for the study of two touching spheres and similar shapes. Since these shapes are thought to correspond to the scission shapes for the high-kinetic-energy events it is of crucial importance that a continuous sequence of shapes leading from the nuclear ground state to these configurations can be studied within the framework of the model. We present the results of the calculations in terms of potential-energy surfaces and fission half-lives for heavy even nuclei. The surfaces are displayed in the form of contour diagrams as functions of two moments of the shape. They clearly show the appearance of a second fission valley, which leads to scission configurations close to tow touching spheres, for fissioning systems in the vicinity of {sup 264}Fm.

Moeller, P. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan); Nix, J.R. [Los Alamos National Lab., NM (United States); Swiatecki, W.J. [Lawrence Berkeley Lab., CA (United States)

1992-03-01T23:59:59.000Z

428

Target and method for the production of fission product molybdenum-99  

DOE Patents [OSTI]

A target for the reduction of fission product Mo-99 is prepared from uranium of low U-235 enrichment by coating a structural support member with a preparatory coating of a substantially oxide-free substrate metal. Uranium metal is electrodeposited from a molten halide electrolytic bath onto a substrate metal. The electrodeposition is performed at a predetermined direct current rate or by using pulsed plating techniques which permit relaxation of accumulated uranium ion concentrations within the melt. Layers of as much as to 600 mg/cm/sup 2/ of uranium can be prepared to provide a sufficient density to produce acceptable concentrations of fission product Mo-99. 2 figs.

Vandegrift, G.F.; Vissers, D.R.; Marshall, S.L.; Varma, R.

1987-10-26T23:59:59.000Z

429

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JULY 1, 2002 THROUGH SEPTEMBER 30, 2002  

SciTech Connect (OSTI)

Direct energy conversion is the only potential means for producing electrical energy from a fission reactor without the Carnot efficiency limitations. This project was undertaken by Sandia National Laboratories, Los Alamos National Laboratories, The University of Florida, Texas A&M University and General Atomics to explore the possibilities of direct energy conversion. Other means of producing electrical energy from a fission reactor, without any moving parts, are also within the statement of proposed work. This report documents the efforts of General Atomics. Sandia National Laboratories, the lead laboratory, provides overall project reporting and documentation.

L.C. BROWN

2002-09-30T23:59:59.000Z

430

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD APRIL 1, 2002 THROUGH JUNE 30, 2002  

SciTech Connect (OSTI)

Direct energy conversion is the only potential means for producing electrical energy from a fission reactor without the Carnot efficiency limitations. This project was undertaken by Sandia National Laboratories, Los Alamos National Laboratories, The University of Florida, Texas A&M University and General Atomics to explore the possibilities of direct energy conversion. Other means of producing electrical energy from a fission reactor, without any moving parts, are also within the statement of proposed work. This report documents the efforts of General Atomics. Sandia National Laboratories, the lead laboratory, provides overall project reporting and documentation.

L.C. BROWN

2002-06-30T23:59:59.000Z

431

New fission fragment distributions and r-process origin of the rare-earth elements  

E-Print Network [OSTI]

Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 rare-earth peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r-nuclei with A > 140.

S. Goriely; J. -L. Sida; J. -F. Lemaitre; S. Panebianco; N. Dubray; S. Hilaire; A. Bauswein; H. -Thomas Janka

2013-11-22T23:59:59.000Z

432

Target and method for the production of fission product molybdenum-99  

DOE Patents [OSTI]

A target for the reduction of fission product Mo-99 is prepared from uranium of low U-235 enrichment by coating a structural support member with a preparatory coating of a substantially oxide-free substrate metal. Uranium metal is electrodeposited from a molten halide electrolytic bath onto a substrate metal. The electrodeposition is performed at a predetermined direct current rate or by using pulsed plating techniques which permit relaxation of accumulated uranium ion concentrations within the melt. Layers of as much as to 600 mg/cm.sup.2 of uranium can be prepared to provide a sufficient density to produce acceptable concentrations of fission product Mo-99.

Vandegrift, George F. (Bolingbrook, IL); Vissers, Donald R. (Naperville, IL); Marshall, Simon L. (Woodridge, IL); Varma, Ravi (Hinsdale, IL)

1989-01-01T23:59:59.000Z

433

The supply chain response to environmental pressures  

E-Print Network [OSTI]

Understanding and shaping the relationship between supply chain management and the natural environment is critical not only to human health and the environment, but to the future success of business. While the cumulative ...

Paquette, Julie Rebecca

2006-01-01T23:59:59.000Z

434

Internal Markets for Supply Chain Capacity Allocation  

E-Print Network [OSTI]

This paper explores the possibility of solving supply chain capacity allocation problems using internal markets among employees of the same company. Unlike earlier forms of transfer pricing, IT now makes it easier for such ...

McAdams, David

2005-07-08T23:59:59.000Z

435

Global supply chain design and optimization methodology  

E-Print Network [OSTI]

The work for this thesis was performed at Honeywell in the Automation and Control Solutions (ACS) division. The project focuses on ACS's manufacturing strategy regarding its global supply chain design, primarily discussing ...

Henkle, Aimee L. (Aimee Leigh), 1975-

2004-01-01T23:59:59.000Z

436

Economic analysis of the meat supply chain  

E-Print Network [OSTI]

and overseas animal disease outbreaks on the Korean meat supply chain. Market impacts are investigated using both forecasts and historical decomposition of price innovations based on an error correction model (ECM) of the Korean meat sector. Results indicate...

Park, Moon-Soo

2009-05-15T23:59:59.000Z

437

Supply chain and the executive agenda  

E-Print Network [OSTI]

In recent years, supply chain pundits and consultants emphasized the importance of strategies such as just-in-time, lean manufacturing, off- shoring or frequent deliveries to retail outlets. However, with significant ...

Peruvankal, James Paul

2011-01-01T23:59:59.000Z

438

Segmentation strategies for managing retail supply chains  

E-Print Network [OSTI]

High-technology manufacturing companies often face rapid price decline and capacity constraints. Especially in the retail side of the business where the supply chain is much longer and revenue is sometimes not recognized ...

Liang, Catherine G. (Catherine Gloria)

2011-01-01T23:59:59.000Z

439

Customer service driven supply chain segmentation  

E-Print Network [OSTI]

The objective of this thesis is to develop a supply chain segmentation model for Company X, which is in the chemical and construction materials industry. The company sells products in an expanding Southeast Asia market. ...

Worawattananon, Prakit

2008-01-01T23:59:59.000Z

440

Supply chain practices in the petroleum downstream  

E-Print Network [OSTI]

This thesis studies current supply chain practices in the petroleum downstream industry, using ExxonMobil as a case study. Based on the analysis of the literature and the interaction with industry experts, this work describes ...

Santos Manzano, Fidel

2005-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Polynomial policies in supply chain networks  

E-Print Network [OSTI]

This thesis aims to solve the periodic-reviewed inventory control problem in supply chain networks with uncertain demand so as to minimize the overall cost of the system over a fixed planning time horizon. In such problems, ...

He, Liwei

2010-01-01T23:59:59.000Z

442

Risk in the Global Supply Chain  

E-Print Network [OSTI]

Carbon footprints are not on the priority list of risk analysts in operations management for at least half or more of global businesses. What are the other risks in the global supply chain?

Datta, Shoumen

2006-01-01T23:59:59.000Z

443

Charge separation in photoredox reactions. Final report  

SciTech Connect (OSTI)

The structural aspects controlling charge separation in molecular photoionization reactions in organized molecular assemblies involving micelles, reverse micelles and vesicles are being studied by optical and electron magnetic resonance techniques including the time domain technique of deuterium electron spin echo modulation (ESEM) and matrix proton electron nuclear double resonance (ENDOR) to measure weak electron-nuclear dipolar interactions. ESEM and matrix ENDOR are particularly well adapted to the study of disordered systems as exemplified by micelles and vesicles. The photoionization yields of alkylphenothiazines in micelles and vesicles have been shown to depend on the alkyl chain length and to correlate with relative distances from the surfactant assembly interface measured by deuterium ESEM and matrix proton ENDOR. The photoionization of alkylmethylviologens versus alkyl chain length has also been studied in vesicles, micelles and reverse micelles. Nitroxide spin probes have been used to study the degree of water penetration into mixed ionic/nonionic poly(ethylene oxide) and cationic/anionic micelles by using ESEM methods and selectively deuterated surfactants. The effect of urea interaction at micellar interfaces on the interface hydration has also been evaluated by studying nitroxide probes with ESEM.

Kevan, L.

1993-07-15T23:59:59.000Z

444

Energy Department Announces $2 Million to Develop Supply Chain...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

2 Million to Develop Supply Chain, Manufacturing Competitiveness Analysis for Hydrogen and Fuel Cell Technologies Energy Department Announces 2 Million to Develop Supply Chain,...

445

Transitions of tethered chain molecules under tension  

E-Print Network [OSTI]

An applied tension force changes the equilibrium conformations of a polymer chain tethered to a planar substrate and thus affects the adsorption transition as well as the coil-globule and crystallization transitions. Conversely, solvent quality and surface attraction are reflected in equilibrium force-extension curves that can be measured in experiments. To investigate these effects theoretically, we study tethered chains under tension with Wang-Landau simulations of a bond-fluctuation lattice model. Applying our model to pulling experiments on biological molecules we obtain a good description of experimental data in the intermediate force range, where universal features dominate and finite size effects are small. For tethered chains in poor solvent, we observe the predicted two-phase coexistence at transitions from the globule to stretched conformations and also discover direct transitions from crystalline to stretched conformations. A phase portrait for finite chains constructed by evaluating the density of states for a broad range of solvent conditions and tensions shows how increasing tension leads to a disappearance of the globular phase. For chains in good solvents tethered to hard and attractive surfaces we find the predicted scaling with the chain length in the low-force regime and show that our results are well described by an analytical, independent-bond approximation for the bond-fluctuation model for the highest tensions. Finally, for a hard or slightly attractive surface the stretching of a tethered chain is a conformational change that does not correspond to a phase transition. However, when the surface attraction is sufficient to adsorb a chain it will undergo a desorption transition at a critical value of the applied force. Our results for force-induced desorption show the transition to be discontinuous with partially desorbed conformations in the coexistence region.

Jutta Luettmer-Strathmann; Kurt Binder

2014-09-09T23:59:59.000Z

446

Fission-barrier parameters of the compound nuclei /sup 245/Cm, /sup 247/Cm, and /sup 249/Cm  

SciTech Connect (OSTI)

The cross section for fission of /sup 248/Cm by neutrons has been measured in the energy interval 0.3< or =E/sub n/< or =5.5 MeV. The measurements were made by the time-of-flight method with use of an underground nuclear explosion as a pulsed neutron source. From the experimental data for the compound nuclei /sup 245/Cm, /sup 247/Cm, and /sup 249/Cm we have evaluated the following characteristics of the fission probability: the inner barrier height E/sup A//sub f/, the curvature parameter h..omega../sub A/ and the ratio of the average neutron and fission widths. Some features of the fission probability curves obtained are discussed, and also the question of the applicability of the systematics for prediction of fission characteristics of heavy nuclei with neutron number N>152.

Fomushkin, E.F.; Novoselov, G.F.; Vinogradov, Y.I.; Gavrilov, V.V.

1982-09-01T23:59:59.000Z

447

Microsoft Word - GNEP Website Glossary 2006-02-03_no_links.doc...  

Broader source: Energy.gov (indexed) [DOE]

Glossary 2006-02-03nolinks.doc More Documents & Publications GNEP Glossary Lesson 5 - Fission and Chain Reactions Generation-IV Roadmap Report of the Fuel Cycle Crosscut Group...

448

Theoretical analyses of (n,xn) reactions on sup 235 U, sup 238 U, sup 237 Np, and sup 239 Pu for ENDF/B-VI  

SciTech Connect (OSTI)

Theoretical analyses were performed of neutron-induced reactions on {sup 235}U, {sup 238}U, {sup 237}Np, and {sup 239}Pu between 0.01 and 20 MeV in order to calculate neutron emission cross sections and spectra for ENDF/B-VI evaluations. Coupled-channel optical model potentials were obtained for each target nucleus by fitting total, elastic, and inelastic scattering cross section data, as well as low-energy average resonance data. The resulting deformed optical model potentials were used to calculate direct (n,n{prime}) cross sections and transmission coefficients for use in Hauser-Feshbach statistical theory analyses. A fission model with multiple barrier representation, width fluctuation corrections, and preequilibrium corrections were included in the analyses. Direct cross sections for higher-lying vibrational states were calculated using DWBA theory, normalized using B(E{ell}) values determined from (d,d{prime}) and Coulomb excitation data, where available, and from systematics otherwise. Initial fission barrier parameters and transition state density enhancements appropriate to the compound systems involved were obtained from previous analyses, especially fits to charged-particle fission probability data. The parameters for the fission model were adjusted for each target system to obtain optimum agreement with direct (n,f) cross section measurements, taking account of the various multichance fission channels, that is, the different compound systems involved. The results from these analyses were used to calculate most of the neutron (n,n), (n,n{prime}), and (n,xn) cross section data in the ENDF/B/VI evaluations for the above nuclei, and all of the energy-angle correlated spectra. The deformed optical model and fission model parameterizations are described. Comparisons are given between the results of these analyses and the previous ENDF/B-V evaluations as well as with the available experimental data. 14 refs., 3 figs., 1 tab.

Young, P.G.; Arthur, E.D.

1991-01-01T23:59:59.000Z

449

Reaction chemistry of cerium  

SciTech Connect (OSTI)

It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

NONE

1997-01-01T23:59:59.000Z

450

Photochemical reaction dynamics  

SciTech Connect (OSTI)

The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.

Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)

1993-12-01T23:59:59.000Z

451

Uncertainty evaluation for the matrix 'solidified state' of fissionable elements  

SciTech Connect (OSTI)

In case of the analysis of the radioactive liquid samples, no matter the relative physical analysis method used, two impediments act that belong to the behavior in time of the dispersion state of the liquid samples to be analyzed and of the standard used in the analysis. That is, one of them refers to the state of the sample to be analyzed when being sampled, which 'alter' during the time elapsed from sampling up to the analysis of the sample. The other impediment is the natural change of the dispersion state of the standard radioactive solutions, due to the occurrence and evolution in time of the radiocolloidal and pseudo-radiocolloidal states. These radiocolloidal states are states of aggregation and they lead to the destruction of the homogeneity of the solutions. Taking into consideration the advantages offered by the relative physical methods of analysis as against the chemical or the radiochemical ones, different ways of eliminating these impediments have been tried. We eliminated these impediments processing the liquid reference materials (the solutions calibrated in radionuclides of interest), immediately after the preparation. This processing changes the liquid physical state of the reference materials in a 'solidified state'. Through this procedure the dispersion states of the samples, practically, can no longer be essentially modified in time and also ensure the uniform distribution of the radionuclides of interest in the elemental matrix of the samples 'state solidified'. The homogeneity of the distribution of the atoms of the radionuclides from the samples 'solidified state' was checked up through the track micromapping technique of the alpha particles. Through this technique, in the chemically etched track detectors that were put in direct contact with the sample for a determined period of time, the alpha exposure time of the detectors, micromaps of alpha tracks were obtained. These micromaps are retorts through tracks of the distributions atoms of fissionable elements (Thorium e.g.), of which, heavy charged particles, in this case the alpha radiations naturally emitted, were registered in the CR-39 track detectors. The density of alpha track from the obtained track micromaps was studied through common optic microscopy. Micromaps were studied counting the tracks on equal areas, in different measurement points. For the study of the foils prepared within the paper, the studied area was of 4.9 mm2, formed of 10 fields of 0.49 mm2 area each. The estimation of the uncertainty was carried out for all the sizes that were measured within the paper, no matter if they participate, directly or indirectly, in the estimation of the uncertainty regarding the homogeneity of the Thorium atoms distribution in the 'solidified state' foils of the standard solution calibrated in Thorium, such as: i) the weighted masses, ii) the dropped volumes of solution, iii) the alpha duration of exposure of the detectors, iv) the area studied on the surface of the micromap and v) the densities of alpha tracks. The procedure suggested allowed us to considerate that the homogeneity of alpha tracks distribution, on the surface and in thickness, is within the limits of 3.1%.

Iliescu, Elena; Iancso, Georgeta [National Institute of R and D for Physics and Nuclear Engineering-'Horia Hulubei', Str.Reactorului 30, P.O. BOX MG-6, Magurele (Romania)

2012-09-06T23:59:59.000Z

452

Key to images: [1] Model system: fission yeast [2] Cryo-EM structure  

E-Print Network [OSTI]

Key to images: [1] Model system: fission yeast [2] Cryo-EM structure of the MCM helicase [3 combing [8] Model system: Xenopus [9] Extreme environments [10] Model system: C.elegans. Background image of the evolution of the replication machinery highlighted. BSRC B306 Email: sam31@st-and.ac.uk 1 2 3 4 5 6 7 8 9 10

Brierley, Andrew

453

Assessment of the high temperature fission chamber technology for the French fast reactor program  

SciTech Connect (OSTI)

High temperature fission chambers are key instruments for the control and protection of the sodium-cooled fast reactor. First, the developments of those neutron detectors, which are carried out either in France or abroad are reviewed. Second, the French realizations are assessed with the use of the technology readiness levels in order to identify tracks of improvement. (authors)

Jammes, C.; Filliatre, P.; Geslot, B.; Domenech, T.; Normand, S. [Commissariat a l'Energie Atomique, CEA (France)

2011-07-01T23:59:59.000Z

454

PHYSICAL REVIEW C 87, 014617 (2013) Monte Carlo Hauser-Feshbach predictions of prompt fission rays  

E-Print Network [OSTI]

Nuclear Theory Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA (Received 14 for the evaporation of the excited fission fragments. Remaining free model parameters, such as excitation energy, multiplicity distribution, average multiplicity and energy, and multiplicity distribution, are calculated

Danon, Yaron

455

Multiple-humped fission and fusion barriers of the heaviest elements and ellipsoidal deformations  

E-Print Network [OSTI]

leading possibly to superheavy elements, double-humped potential barriers appear for cold fusionMultiple-humped fission and fusion barriers of the heaviest elements and ellipsoidal deformations G barriers and the predicted half-lives of actinides follow the experimental results. In the fusion path

Boyer, Edmond

456

Detection of uranium-based nuclear weapons using neutron-induced fission  

SciTech Connect (OSTI)

Although plutonium-based nuclear weapons can usually be detected by their spontaneous emission of neutrons and gammas, the radiation emitted by weapons based entirely on highly-enriched uranium can often be easily shielded. Verification of a treaty that limits the number of such weapons may require an active technique, such as interrogating the suspect assembly with an external neutron source and measuring the number of fission neutrons produced. Difficulties include distinguishing between source and fissio