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1

Lesson 5- Fission and Chain Reactions  

Energy.gov (U.S. Department of Energy (DOE))

Lesson Four showed how the nuclei of atoms store energy and how unstable atoms decay and release energy. How do nuclear engineers use this knowledge to help them harness energy to make electricity? The answer lies in being able to start a nuclear chain reaction in fuel inside a nuclear power plant and keep it going. This lesson examines nuclear reactions called fission as well as how uranium is processed from ore to fuel.

2

NUCLEAR FISSION CHAIN REACTING SYSTEM  

DOE Patents (OSTI)

The patent describes a reactor consisting of a plurality of tubes passing through a body of heavy water or graphite, a heat exchanger, means for flowing UF/sub 6/ through the tubes and the heat exchangar, and means for bleeding off some of the UF/sub 6/ and separating plutonium therefrom. A specific suggestion contained is that the amount of the UF/sub 6/ outside the reaction unit be a multiple of that within it.

Anderson, H.L.; Brown, H.S.

1961-06-27T23:59:59.000Z

3

Nukes (notes on PFFP) Chain reactions  

E-Print Network (OSTI)

corresponds to 300 million kg of TNT = 300 ktons Energetics But the Hiroshima bomb (10 kg) only release 20 Clouds" Nagasaki Atomic Bomb 1945 Volcanic Eruption (Mount Redoubt) Not characteristic of nuclear bombs weapons and nuclear power reactors. #12;Chain reactions in nuclear fission bomb Note the number

Browder, Tom

4

On "Sub-Threshold" Reactions Involving Nuclear Fission  

E-Print Network (OSTI)

We analyze reactions of several types that are naively below threshold but can proceed because of the release of binding energy from nuclear fission and occasionally the formation of Coulombic bound states. These reactions include (i) photofission with pion production and (ii) charged current neutrino-nucleus reactions that lead to fission and/or formation of a Coulomb bound state of a $\\mu^-$ with the nucleus of a fission fragment. We comment on the possible experimental observation of these reactions.

M. Goldhaber; R. Shrock

2000-11-29T23:59:59.000Z

5

Emilio Segrč and Spontaneous Fission  

Office of Scientific and Technical Information (OSTI)

however, had revealed that the uranium fissioned instead. The discovery of fission led in turn to the discovery of the chain reaction that, if sustained, would provide the...

6

Statistical Model of Heavy-Ion Fusion-Fission Reactions  

E-Print Network (OSTI)

Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with the fission of fully equilibrated systems with fission lifetime estimates obtained via a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state, the temperature dependence of the location and height of fission transition points, and the orientation degree of freedom. If the standard techniques for calculating fission lifetimes are used, then the calculated excitation-energy dependence of fission lifetimes is incorrect. We see no evidence to suggest that the nuclear viscosity has a temperature dependence. The strong increase in the nuclear viscosity above a temperature of approximately 1.3 MeV deduced by others is an artifact generated by an inadequate fission model.

J. P. Lestone; S. G. McCalla

2008-07-21T23:59:59.000Z

7

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

8

Unified description of fission in fusion and spallation reactions  

E-Print Network (OSTI)

We present a statistical-model description of fission, in the framework of compound-nucleus decay, which is found to simultaneously reproduce data from both heavy-ion-induced fusion reactions and proton-induced spallation reactions at around 1 GeV. For the spallation reactions, the initial compound-nucleus population is predicted by the Li\\`{e}ge Intranuclear Cascade Model. We are able to reproduce experimental fission probabilities and fission-fragment mass distributions in both reactions types with the same parameter sets. However, no unique parameter set was obtained for the fission probability. The introduction of fission transients can be offset by an increase of the ratio of level-density parameters for the saddle-point and ground-state configurations. Changes to the finite-range fission barriers could be offset by a scaling of the Bohr-Wheeler decay width as predicted by Kramers. The parameter sets presented allow accurate prediction of fission probabilities for excitation energies up to 300 MeV and spins up to 60 \\hbar.

Davide Mancusi; Robert J. Charity; Joseph Cugnon

2010-07-06T23:59:59.000Z

9

Fission Decay Widths for Heavy-Ion Fusion-Fission Reactions  

E-Print Network (OSTI)

Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state; the temperature dependence of the location of fission transition points; and the orientation degree of freedom. We see no evidence to suggest that the nuclear viscosity departs from the surface-plus-window dissipation model. The strong increase in the nuclear viscosity above a temperature of ~1 MeV deduced by others is an artifact generated by an inadequate fission model.

S. G. McCalla; J. P. Lestone

2008-01-30T23:59:59.000Z

10

On the rearrangement time of the fission reaction  

E-Print Network (OSTI)

The rearrangement time \\Deltat of the fission reaction can be extracted from the full-width at half maximum (f.w.h.m.) of the isotopic distributions of fission fragments if this width is attributed to an uncertainty \\DeltaN in the neutron-number N of the fragment; then the energy-time uncertainty relation leads to \\Deltat = 0.17 yoctosecond.

G. Mouze; C. Ythier

2010-04-08T23:59:59.000Z

11

Nuclear Fission: Reaction to the Discovery in 1939  

E-Print Network (OSTI)

and A. v. Grosse, "Nuclear fission of separated uraniumThe mechanism of nuclear fission," Physical Review, 56 (1liberated in the nuclear fission of uranium," Nature, 143 (

Hodes, Elizabeth; Tiddens, Adolph; Badash, Lawrence

1985-01-01T23:59:59.000Z

12

REACTION BEHAVIOR OF ZIRCALOY WITH SIMULATED FISSION PRODUCTS  

E-Print Network (OSTI)

ZIRCALOY WITH SIMULATED FISSION PRODUCTS Rajiv Kohli JanuaryOF ZIRCALOY WITH SIMULATED FISSION PRODUCTS Rajiv Kohlion long-term exposure to fission product environments in the

Kohli, R.

2010-01-01T23:59:59.000Z

13

Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction...  

National Nuclear Security Administration (NNSA)

Achieves First Self Sustain Nuclear Chain Reaction Metallurgical Laboratory scientists led by Enrico Fermi achieve the first self-sustained nuclear chain reaction in pile...

14

Quasi-fission reactions as a probe of nuclear viscosity  

E-Print Network (OSTI)

Fission fragment mass and angular distributions were measured from the ^{64}Ni+^{197}Au reaction at 418 MeV and 383 MeV incident energy. A detailed data analysis was performed, using the one-body dissipation theory implemented in the code HICOL. The effect of the window and the wall friction on the experimental observables was investigated. Friction stronger than one-body was also considered. The mass and angular distributions were consistent with one-body dissipation. An evaporation code DIFHEAT coupled to HICOL was developed in order to predict reaction time scales required to describe available data on pre-scission neutron multiplicities. The multiplicity data were again consistent with one-body dissipation. The cross-sections for touch, capture and quasi-fission were also obtained.

J. Velkovska; C. R. Morton; R. L. McGrath; P. Chung; I. Dioszegi

1998-07-26T23:59:59.000Z

15

FREYA-a new Monte Carlo code for improved modeling of fission chains  

Science Conference Proceedings (OSTI)

A new simulation capability for modeling of individual fission events and chains and the transport of fission products in materials is presented. FREYA ( Fission Yield Event Yield Algorithm ) is a Monte Carlo code for generating fission events providing correlated kinematic information for prompt neutrons, gammas, and fragments. As a standalone code, FREYA calculates quantities such as multiplicity-energy, angular, and gamma-neutron energy sharing correlations. To study materials with multiplication, shielding effects, and detectors, we have integrated FREYA into the general purpose Monte Carlo code MCNP. This new tool will allow more accurate modeling of detector responses including correlations and the development of SNM detectors with increased sensitivity.

Hagmann, C A; Randrup, J; Vogt, R L

2012-06-12T23:59:59.000Z

16

MEANS FOR PRODUCING PLUTONIUM CHAIN REACTIONS  

DOE Patents (OSTI)

A neutronic reactor is described with an active portion capable of operating at an energy level of 0.5 to 1000 ev comprising discrete bodies of Pu/ sup 239/ disposed in a body of water which contains not more than 5 molecules of water to one atom of plutonium, the total amount of Pu/sup 239/ being sufficient to sustain a chain reaction. (auth)

Wigner, E.P.; Weinberg, A.M.

1961-01-24T23:59:59.000Z

17

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

18

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

19

Inverse beta decay reaction in 232 Th and 233 U fission antineutrino flux  

E-Print Network (OSTI)

Energy spectra of antineutrinos coming from 232 Th and 233 U neutroninduced fission are calculated, relevant inverse beta decay Ż?e + p ? n+e + positron spectra and total cross sections are found. This study is stimulated by a hypothesis that a self-sustained nuclear chain reaction is burning at the center of the Earth (“Georeactor”). The Georeactor, according to the author of this idea, provides energy necessary to sustain the Earth’s magnetic field. The Georeactor’s nuclear fuel is 235 U and, probably, 232 Th and 233 U. Results of present study may appear to be useful in future experiments aimed to test the Georector hypothesis and to estimate its fuel components as a part of developments in geophysics and astrophysics based on observations of low energy antineutrinos in Nature.

G. Domogatski; V. Kopeikin; L. Mikaelyan; V. Sinev

2004-01-01T23:59:59.000Z

20

Nuclear Fission: Reaction to the Discovery in 1939  

E-Print Network (OSTI)

the destruction of cities by nuclear fission killed millionsnuclear energy. Elizabeth Hodes is a professor of mathematics at Santa Barbara City

Hodes, Elizabeth; Tiddens, Adolph; Badash, Lawrence

1985-01-01T23:59:59.000Z

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.


21

Microscopic Calculation of Fission Fragment Energies for the 239Pu(nth,f) Reaction  

SciTech Connect

We calculate the total kinetic and excitation energies of fragments produced in the thermal-induced fission of {sup 239}Pu. This result is a proof-of-principle demonstration for a microscopic approach to the calculation of fission-fragment observables for applied data needs. In addition, the calculations highlight the application of a fully quantum mechanical description of scission, and the importance of exploring scission configurations as a function of the moments of the fragments, rather than through global constraints on the moments of the fissioning nucleus. Using a static microscopic calculation of configurations at and near scission, we have identified fission fragments for the {sup 239}Pu (n{sub th}, f) reaction and extracted their total kinetic and excitation energies. Comparison with data shows very good overall agreement between theory and experiment. Beyond their success as a proof of principle, these calculations also highlight the importance of local constraints on the fragments themselves in microscopic calculations.

Younes, W; Gogny, D

2011-10-03T23:59:59.000Z

22

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

SciTech Connect

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

23

Initiation of persistent fission chains in the fast burst reactor Caliban  

SciTech Connect

We provide in this article, experimental data of initiation of persistent fission chains obtained at different supercritical states, using the Fast Burst Reactor CALIBAN. In many past papers, theory has been compared mostly to initiation experiments at various super-prompt critical states, whereas very few experimental data has been published in delayed supercritical states. To fill the lack of data, we have conducted three campaigns on the reactor at reactivities far below 0.7$ which was one of the rare lowest state ever published on a similar assembly [2][1]. We give a justification of the use of the gamma function to fit experimental results of the temporal distributions of waiting times and compare experiments with numerical simulations obtained with a zero-D punctual Monte Carlo code. (authors)

Authier, N.; Richard, B.; Grivot, P.; Casoli, P. [Commissariat a l'Energie Atomique et Aux Energies Alternatives CEA DAM, Centre de Val Duc, 21120 Is-sur-Tille (France); Humbert, P. [Commissariat a l'Energie Atomique et Aux Energies Alternatives CEA DAM, Centre de Bruyeres-le-chatel, 91297 Arpajon Cedex (France)

2012-07-01T23:59:59.000Z

24

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

25

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

26

Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction | National  

National Nuclear Security Administration (NNSA)

Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction | National Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction | National Nuclear Security Administration Our Mission Managing the Stockpile Preventing Proliferation Powering the Nuclear Navy Emergency Response Recapitalizing Our Infrastructure Continuing Management Reform Countering Nuclear Terrorism About Us Our Programs Our History Who We Are Our Leadership Our Locations Budget Our Operations Media Room Congressional Testimony Fact Sheets Newsletters Press Releases Speeches Events Social Media Video Gallery Photo Gallery NNSA Archive Federal Employment Apply for Our Jobs Our Jobs Working at NNSA Blog Home > About Us > Our History > NNSA Timeline > Enrico Fermi Achieves First Self Sustain Nuclear ... Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction

27

The calculation of prompt fission neutron spectrum for 233U(n,f) reaction by the semi-empirical method  

E-Print Network (OSTI)

The prompt fission neutron spectra for neutron-induced fission of 233U for low energy neutrons (below 6 MeV) are calculated using the nuclear evaporation theory with a semi-empirical method, in which the partition of the total excitation energy between the fission fragments for the nth+233U fission reactions are determined with the available experimental and evaluation data. The calculated prompt fission neutron spectra agree well with the experimental data. The proportions of high- energy outgoing neutrons of prompt fission neutron spectrum versus incident neutron energies are investigated with the theoretical spectra, and the results are consistent with the systematics. We conclude that the semi-empirical method is sound, and it could be a useful tool for prompt fission neutron spectra evaluation.

Yong-Jing Chen; Jia Min; Ting-Jin Liu; Neng-Chuan Shu

2013-06-13T23:59:59.000Z

28

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

Science Conference Proceedings (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

29

Pre-saddle neutron multiplicity for fission reactions induced by heavy ions and light particles  

E-Print Network (OSTI)

Pre-saddle neutron multiplicity has been calculated for several fission reactions induced by heavy ions and light particles. Experimentally, it is impossible to determine the contribution of neutrons being emitted before the saddle point and those emitted between the saddle and the scission points. Determination of the pre-saddle neutron multiplicity in our research is based on the comparison between the experimental anisotropies and those predicted by the standard saddle-point statistical model. Analysis of the results shows that the pre-saddle neutron multiplicity depends on the fission barrier height and stability of the compound nucleus. In heavy ion induced fission, the number of pre-saddle neutrons decreases with increasing the excitation energy of the compound nucleus. A main cause of this behavior is due to a reduction in the ground state-to-saddle point transition time with increasing the excitation energy of the compound nucleus. Whereas in induced fission by light particles, the number of pre-saddle neutrons increases with increasing the excitation energy of the compound nucleus.

S. Soheyli; M. K. Khalili

2013-06-03T23:59:59.000Z

30

Isotopic Yield Distributions of Transfer- and Fusion-Induced Fission from 238U+12C Reactions in Inverse Kinematics  

E-Print Network (OSTI)

A novel method to access the complete identification in atomic number Z and mass A of fragments produced in low-energy fission of actinides is presented. This method, based on the use of multi- nucleon transfer and fusion reactions in inverse kinematics, is applied in this work to reactions between a 238U beam and a 12C target to produce and induce fission of moderately excited actinides. The fission fragments are detected and fully identified with the VAMOS spectrometer of GANIL, allowing the measurement of fragment yields of several hundreds of isotopes in a range between A ~ 80 and ~ 160, and from Z ~ 30 to ~ 64. For the first time, complete isotopic yield distributions of fragments from well-defined fissioning systems are available. Together with the precise measurement of the fragment emission angles and velocities, this technique gives further insight into the nuclear-fission process.

M. Caamańo; O. Delaune; F. Farget; X. Derkx; K. -H. Schmidt; L. Audouin; C. -O. Bacri; G. Barreau; J. Benlliure; E. Casarejos; A. Chbihi; B. Fernandez-Dominguez; L. Gaudefroy; C. Golabek; B. Jurado; A. Lemasson; A. Navin; M. Rejmund; T. Roger; A. Shrivastava; C. Schmitt

2013-04-09T23:59:59.000Z

31

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

E-Print Network (OSTI)

The pre-scission time in the de-excitation of highly excited 178W produced in the reaction of 2ONe + 165Ho at 50A MeV was determined as a function of fission fragment mass asymmetry. The techniques employed used the pre-scission and post scission multiplicities of alpha particles, measured in coincidence with the fission fragments, to determine excitation energy of the fissioning nucleus at scission. Then the fission time was evaluated using statistical model calculations. It was found for a compound system of mass 178 amu and excitation energy of 580 MeV that the fission time is [ ] 1 x 10-20 s regardless of the asymmetry.

Mdeiwayeh, Nader

1995-01-01T23:59:59.000Z

32

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

SciTech Connect

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

33

Crossover from a fission-evaporation scenario towards multifragmentation in spallation reactions  

E-Print Network (OSTI)

Mostly for the purpose of applications for the energy and the environment and for the design of sources of neutrons or exotic nuclides, intense research has been dedicated to spallation, induced by protons or light projectiles at incident energies of around 1 GeV. In this energy range, while multifragmentation has still a minor share in the total reaction cross section, it was observed to have, together with fission, a prominent role in the production and the kinematics of intermediate-mass fragments, so as to condition the whole production of light and heavy nuclides. The experimental observables we dispose of attribute rather elusive properties to the intermediate-mass fragments and do not allow to classify them within one exclusive picture which is either multifragmentation or fission. Indeed, these two decay mechanisms, driven by different kinds of instabilities, exhibit behaviours which are closely comparable. High-resolution measurements of the reaction kinematics trace the way for probing finer features of the reaction kinematics.

P. Napolitani

2006-10-26T23:59:59.000Z

34

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

Science Conference Proceedings (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

35

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

SciTech Connect

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

36

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

37

Buoyancy-Driven Polymerase Chain Reaction (PCR) Devices  

Science Conference Proceedings (OSTI)

Polymerase chain reaction (PCR) facilitates DNA detection by significantly increasing the concentration of specific DNA segments. A new class of PCR instruments uses a buoyancy-driven re-circulating flow to thermally cycle the DNA sample and benefits from reduced cycle times, low sample volumes, a miniaturized format, and low power consumption. This paper analyzes a specific buoyancy PCR device in a micro-channel ''race-track'' geometry to determine key parameters about PCR cycle times and other figures of merit as functions of device dimensions. The 1-D model balances the buoyancy driving force with frictional losses. A hydrostatic pressure imbalance concept is used between the left and right sides of the fluid loop to calculate the buoyancy driving force. Velocity and temperature distributions within the channels are determined from two-dimensional analysis of the channel section, with developing region effects included empirically through scaled values of the local Nusselt number. Good agreement between four independent verification steps validate the 1-D simulation approach: (1) analytical expressions for the thermal entrance length are compared against, (2) comparison with a full 3-D finite element simulation, (3) comparison with an experimental flow field characterization, and (4) calculation of the minimum PCR runtime required to get a positive PCR signal from the buoyancy-driven PCR device. The 1-D approach closely models an actual buoyancy-driven PCR device and can further be used as a rapid design tool to simulate buoyancy PCR flows and perform detailed design optimizations studies.

Ness, K D; Wheeler, E K; Benett, W; Stratton, P; Christian, A; Chen, A; Ortega, J; Weisgraber, T H; Goodson, K E

2004-09-28T23:59:59.000Z

38

Inverse beta decay reaction in $^{232}$Th and $^{233}$U fission antineutrino flux  

E-Print Network (OSTI)

Energy spectra of antineutrinos coming from $^{232}$Th and $^{233}$U neutron-induced fission are calculated, relevant inverse beta decay $\\bar{{\

G. Domogatski; V. Kopeikin; L. Mikaelyan; V. Sinev

2004-03-15T23:59:59.000Z

39

Use of the polymerase chain reaction (PCR) to differentiate serologically similar viral  

E-Print Network (OSTI)

Use of the polymerase chain reaction (PCR) to differentiate serologically similar viral isolates. Through the use of PCR (polymerase chain reaction) and specific primer sets for the amplification within half a day. VHSV / N gene / viral RNA purification / reverse transcription / PCR / genetic

Recanati, Catherine

40

Coulomb effects in cold fission from reactions 233U(nth,f) and 235U(nth,f)  

E-Print Network (OSTI)

The Coulomb effect hypothesis in cold fission, formerly used to interpret fluctuations in the curve of maximal total kinetic energy as a function of fragments mass, in reactions 233U(nth,f), 235U(nth,f) and 239Pu(nth,f), is confirmed by the preference for more asymmetrical charge splits observed in cold fragmentations. Several experimental results on reactions 233U(nth,f) and 235U(nth,f) show that, for two isobaric fragmentations with similar Q-values, the greater is the value of the kinetic energy of the fragments, the greater will be the probability of more asymmetric charge split.

Modesto Montoya

2013-10-03T23:59:59.000Z

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.


41

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, S.M. Massachusetts Institute of Technology

2009-01-01T23:59:59.000Z

42

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

First-Hand Recollections of the First Self-Sustaining Chain First-Hand Recollections of the First Self-Sustaining Chain Reaction First-Hand Recollections of the First Self-Sustaining Chain Reaction August 3, 2012 - 4:53pm Addthis On December 2, 1942, 49 scientists, led by Enrico Fermi, made history when Chicago Pile 1 (CP-1) went critical and produced the world's first self-sustaining, controlled nuclear chain reaction. Seventy years later, two of the last surviving CP-1 pioneers, Harold Agnew and Warren Nyer, recall that historic day. Michael Hess Michael Hess Former Digital Communications Specialist, Office of Public Affairs How were the natives? A small graphite block from the pile is on display at the Museum of Science and Industry in Chicago; another can be seen at the Bradbury Science Museum in Los Alamos, NM.

43

FISSION AND SPALLATION EXCITATION FUNCTIONS OF U238  

E-Print Network (OSTI)

Spallation Cro ss Sections Fission Product Cross Sections V.B. Spallation Reactions Fission Yields Acknowledgme nts . .UNIVERSITY OF CALIFORNIA ;"~I FISSION SPALLATION EXCITATION

Ritsema, Susanne Elaine

2010-01-01T23:59:59.000Z

44

Fission theory and actinide fission data  

SciTech Connect

The understanding of the fission process has made great progress recently, as a result of the calculation of fission barriers, using the Strutinsky prescription. Double-humped shapes were obtained for nuclei in the actinide region. Such shapes could explain, in a coherent manner, many different phenomena: fission isomers, structure in near-threshold fission cross sections, intermediate structure in subthreshold fission cross sections and anisotropy in the emission of the fission fragments. A brief review of fission barrier calculations and relevant experimental data is presented. Calculations of fission cross sections, using double-humped barrier shapes and fission channel properties, as obtained from the data discussed previously, are given for some U and Pu isotopes. The fission channel theory of A. Bohr has greatly influenced the study of low-energy fission. However, recent investigation of the yields of prompt neutrons and ..gamma.. rays emitted in the resonances of /sup 235/U and /sup 239/Pu, together with the spin determination for many resonances of these two nuclei cannot be explained purely in terms of the Bohr theory. Variation in the prompt neutron and ..gamma..-ray yields from resonance to resonance does not seem to be due to such fission channels, as was thought previously, but to the effect of the (n, ..gamma.., f) reaction. The number of prompt fission neutrons and the kinetic energy of the fission fragments are affected by the energy balance and damping or viscosity effects in the last stage of the fission process, from saddle point to scission. These effects are discussed for some nuclei, especially for /sup 240/Pu. 17 figures, 56 ref. (auth)

Michaudon, A.

1975-10-01T23:59:59.000Z

45

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

46

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

47

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

2004-01-01T23:59:59.000Z

48

"FISSION" OF MEDIUM WEIGHT ELEMENTS  

E-Print Network (OSTI)

Contract NO e W~7405~eng~4B "FISSION" OF w~IU11 w~IGHT EL~~California May The fission reaction has been observed withmore properly be termed fission, Cu b3 As an example 9 the

Batzel., Roger T.; Seaborg, G.T.

2008-01-01T23:59:59.000Z

49

Equilibrium Properties of A Monomer-Monomer Catalytic Reaction on A One-Dimensional Chain  

E-Print Network (OSTI)

We study the equilibrium properties of a lattice-gas model of an $A + B \\to 0$ catalytic reaction on a one-dimensional chain in contact with a reservoir for the particles. The particles of species $A$ and $B$ are in thermal contact with their vapor phases acting as reservoirs, i.e., they may adsorb onto empty lattice sites and may desorb from the lattice. If adsorbed $A$ and $B$ particles appear at neighboring lattice sites they instantaneously react and both desorb. For this model of a catalytic reaction in the adsorption-controlled limit, we derive analytically the expression of the pressure and present exact results for the mean densities of particles and for the compressibilities of the adsorbate as function of the chemical potentials of the two species.

G. Oshanin; M. N. Popescu; S. Dietrich

2003-01-19T23:59:59.000Z

50

Monitoring Acidophilic Microbes with Real-Time Polymerase Chain Reaction (PCR) Assays  

Science Conference Proceedings (OSTI)

Many techniques that are used to characterize and monitor microbial populations associated with sulfide mineral bioleaching require the cultivation of the organisms on solid or liquid media. Chemolithotrophic species, such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, or thermophilic chemolithotrophs, such as Acidianus brierleyi and Sulfolobus solfataricus can grow quite slowly, requiring weeks to complete efforts to identify and quantify these microbes associated with bioleach samples. Real-time PCR (polymerase chain reaction) assays in which DNA targets are amplified in the presence of fluorescent oligonucleotide primers, allowing the monitoring and quantification of the amplification reactions as they progress, provide a means of rapidly detecting the presence of microbial species of interest, and their relative abundance in a sample. This presentation will describe the design and use of such assays to monitor acidophilic microbes in the environment and in bioleaching operations. These assays provide results within 2-3 hours, and can detect less than 100 individual microbial cells.

Frank F. Roberto

2008-08-01T23:59:59.000Z

51

Equilibrium Properties of A Monomer-Monomer Catalytic Reaction on A One-Dimensional Chain  

E-Print Network (OSTI)

We study the equilibrium properties of a lattice-gas model of an A + B ? 0 catalytic reaction on a one-dimensional chain in contact with a reservoir for the particles. The particles of species A and B are in thermal contact with their vapor phases acting as reservoirs, i.e., they may adsorb onto empty lattice sites and may desorb from the lattice. If adsorbed A and B particles appear at neighboring lattice sites they instantaneously react and both desorb. For this model of a catalytic reaction in the adsorption-controlled limit, we derive analytically the expression of the pressure and present exact results for the mean densities of particles and for the compressibilities of the adsorbate as function of the chemical potentials of the two species. During the two decades following the work of Ziff, Gulari, and Barshad (ZGB) [1] there has been a remarkable development in the theoretical analysis of catalytically activated reactions. The ZGB model, sometimes referred to as the “monomer-dimer ” model, has been introduced to describe the important process of oxidation of carbon monoxide on a catalytic surface [2].

G. Oshanin; M. N. Popescu; S. Dietrich

2003-01-01T23:59:59.000Z

52

Intraspecific differentiation of Aureobasidium spp. using universally primed polymerase chain reaction  

Science Conference Proceedings (OSTI)

Universally primed polymerase chain reaction (UP-PCR) was used to analyze intraspecific variation in previously diagnosed biological species of yeastlike Aureobasidium fungi. No correlation between PCR-polymorphism and the origin of fungal strains was revealed. It is suggested that Aureobasidium species studied differ in the width of their ecological niches: species I is cosmopolitan, whereas species II demonstrates relative substrate specificity. The ability of different universal primers to operate as conservative or variable ones in experiments with different species and genera was confirmed. This ability is explained by different rates of evolution of amplified loci. Hybridization analysis of amplified DNA is suggested as a necessary step in classifying strains with insufficient similarity of PCR patterns as belonging to the same divergent species or to different species. 12 refs., 4 figs., 1 tab.

Mokrousov, I.V. [Pasteur Institute, St. Petersburg (Russian Federation)

1995-07-01T23:59:59.000Z

53

Preparation of 13C/15N-labeled oligomers using the polymerase chain reaction  

DOE Patents (OSTI)

Preparation of .sup.13 C/.sup.15 N-labeled DNA oligomers using the polymerase chain reaction (PCR). A PCR based method for uniform (.sup.13 C/.sup.15 N)-labeling of DNA duplexes is described. Multiple copies of a blunt-ended duplex are cloned into a plasmid, each copy containing the sequence of interest and restriction Hinc II sequences at both the 5' and 3' ends. PCR using bi-directional primers and uniformly .sup.13 C/.sup.15 N-labeled dNTP precursors generates labeled DNA duplexes containing multiple copies of the sequence of interest. Twenty-four cycles of PCR, followed by restriction and purification, gave the uniformly .sup.13 C/.sup.15 N-labeled duplex sequence with a 30% yield. Such labeled duplexes find significant applications in multinuclear magnetic resonance spectroscopy.

Chen, Xian (Los Alamos, NM); Gupta, Goutam (Santa Fe, NM); Bradbury, E. Morton (Santa Fe, NM)

2001-01-01T23:59:59.000Z

54

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

E-Print Network (OSTI)

it is unlikely that nuclear fission power plants willIn the case of nuclear fission reactions, the fundamentalaspects of nuclear fusion and fission. This approach, termed

Kramer, Kevin James

2010-01-01T23:59:59.000Z

56

Background for Terrestrial Antineutrino Investigations: Radionuclide Distribution, Georeactor Fission Events, and Boundary Conditions on Fission Power Production  

E-Print Network (OSTI)

Estimated masses of fissioning and non-fissioning radioactive elements and their respective distributions within the Earth are presented, based upon the fundamental identity of the components of the interior 82% of the Earth, the endo-Earth, with corresponding components of the Abee enstatite chondrite meteorite. Within limits of existing data, the following generalizations concerning the endo-Earth radionuclides can be made: (1) Most of the K-40 may be expected to exist in combination with oxygen in the silicates of the lower mantle, perhaps being confined to the upper region of the lower mantle where it transitions to the upper mantle; (2) Uranium may be expected to exist at the center of the Earth where it may undergo self-sustaining nuclear fission chain reactions, but there is a possibility that some non-fissioning uranium may be found scattered diffusely within the core floaters which are composed of CaS and MgS; and, (3) Thorium may be expected to occur within the core floaters at the core-mantle boundary, although its presence as well at the center of the Earth cannot be ruled out. Results of nuclear georeactor numerical simulations show: (1) The maximum constant nuclear fission power level is 30 terawatts; (2) U-235 comprises 76 percent of present-day georeactor fission, U-238 comprises 23 percent; and, (3) Thorium can neither be fuel nor converted into fuel for the georeactor.

J. Marvin Herndon; Dennis A. Edgerley

2005-01-24T23:59:59.000Z

57

Fission fragment driven neutron source  

DOE Patents (OSTI)

Fissionable uranium formed into a foil is bombarded with thermal neutrons in the presence of deuterium-tritium gas. The resulting fission fragments impart energy to accelerate deuterium and tritium particles which in turn provide approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He.

Miller, Lowell G. (Idaho Falls, ID); Young, Robert C. (Idaho Falls, ID); Brugger, Robert M. (Columbia, MO)

1976-01-01T23:59:59.000Z

58

Dynamical Simulation of Gamma-Ray Multiplicity in B10+Np23, B11+ Th232, C12+Th232, O16 +Th232 Heavy Ion Fusion-Fission Reactions  

Science Conference Proceedings (OSTI)

The passive Q-switched performance of the ruby laser with slow-relaxing solid-state saturable absorber calcium fluoride crystals doped with divalent dysprosium Dy2+:CaF2 is numerical simulation, saturable absorber, Q-switch. is numerically investigated ... Keywords: (fusion-fission reactions, Langevin equations, Monte Carlo simulation, ?-ray multiplicity)

M. R. Pahlavani; S. M. Mirfathi; D. Naderi

2010-05-01T23:59:59.000Z

59

Indirect measurements of reactions in hot p-p chain and CNO cycles  

Science Conference Proceedings (OSTI)

Several reactions have been experimentally studied, including the {sup 12}N(d,n){sup 13}O and the ones induced by the {sup 3}He+{sup 12}C entrance channel. The former was carried out at the CRIB facility of University of Tokyo, aiming to indirectly determine the astrophysical reaction rates of the {sup 12}N(p,{gamma}){sup 13}O reaction. For the {sup 3}He+{sup 12}C entrance channel, many excited states of several nuclei are populated and the angular distribution of each state is being analyzed.

Wang, Y. B.; Guo, B.; Jin, S. J.; Li, Z. H.; Binh, D. N.; Hashimoto, H.; Hayakawa, S.; He, J. J.; Hu, J.; Iwasa, N.; Kahl, D. M.; Kubono, S.; Kume, N.; Li, E. T.; Li, Y. J.; Liu, X.; Su, J.; Xu, S. W.; Yamaguchi, H.; Yan, S. Q. [China Institute of Atomic Energy, PO Box 275 (10), Beijing 102413 (China); Center for Nuclear Study, University of Tokyo, Wako (Japan); Institute of Modern Physics, China Academy of Sciences, Lanzhou (China); Department of Physics, Tohoku university, Sendai (Japan); Center for Nuclear Study, University of Tokyo, Wako (Japan); Department of Physics, Tohoku university, Sendai (Japan); China Institute of Atomic Energy, PO Box 275 (10), Beijing 102413 (China); Institute of Modern Physics, China Academy of Sciences, Lanzhou (China); Center for Nuclear Study, University of Tokyo, Wako (Japan); China Institute of Atomic Energy, PO Box 275 (10), Beijing 102413 (China); and others

2012-11-12T23:59:59.000Z

60

Mathematical Modeling and Simulation of Denaturation Temperature Gradient Polymerase Chain Reaction  

E-Print Network (OSTI)

Ji Youn Lee, Hee-Woong Lim , Suk-In Yoo , Byoung-Tak Zhang and Tai Hyun Park School of Chemical amplification of nucleic acids, which is applicable to versatile biochemical applications. PCR plays is formulated with kinetic constants of hybridization reactions while the extension step is formulated

Yoo, SukIn

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

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

Science Conference Proceedings (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

62

Compact fission counter for DANCE  

SciTech Connect

The Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 BF{sub 2} crystals with equal solid-angle coverage. DANCE is a 4{pi} {gamma}-ray calorimeter and designed to study the neutron-capture reactions on small quantities of radioactive and rare stable nuclei. These reactions are important for the radiochemistry applications and modeling the element production in stars. The recognition of capture event is made by the summed {gamma}-ray energy which is equivalent of the reaction Q-value and unique for a given capture reaction. For a selective group of actinides, where the neutron-induced fission reaction competes favorably with the neutron capture reaction, additional signature is needed to distinguish between fission and capture {gamma} rays for the DANCE measurement. This can be accomplished by introducing a detector system to tag fission fragments and thus establish a unique signature for the fission event. Once this system is implemented, one has the opportunity to study not only the capture but also fission reactions. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to {alpha} particles, which is important for experiments with {alpha}-emitting actinides. Therefore, a PPAC is an ideal detector for experiments requiring a fast and clean trigger for fission. A PPAC with an ingenious design was fabricated in 2006 by integrating amplifiers into the target assembly. However, this counter was proved to be unsuitable for this application because of issues related to the stability of amplifiers and the ability to separate fission fragments from {alpha}'s. Therefore, a new design is needed. A LLNL proposal to develop a new PPAC for DANCE was funded by NA22 in FY09. The design goal is to minimize the mass for the proposed counter and still be able to maintain a stable operation under extreme radioactivity and the ability to separate fission fragments from {alpha}'s. In the following sections, the description is given for the design and performance of this new compact PPAC, for studying the neutron-induced reactions on actinides using DANCE at LANL.

Wu, C Y; Chyzh, A; Kwan, E; Henderson, R; Gostic, J; Carter, D; Bredeweg, T; Couture, A; Jandel, M; Ullmann, J

2010-11-06T23:59:59.000Z

63

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

64

Laser-initiated chain reactions in the partial oxidation of methane  

DOE Green Energy (OSTI)

Using laser photolysis of suitable precursor molecules to produce gas-phase free radicals, we have been studying important kinetic processes in the partial oxidation of methane. Prompt production of a relatively high concentration of free radicals via laser photolysis makes it possible to separate the thermal initiation step from the subsequent chain propagation steps. Since the conditions (temperature, pressure, and mixture composition) for rapid thermal initiation and optimum production may differ, this provides an exciting potential application for laser-induced chemistry where the laser acts as the initiation source. We report our results on the partial oxidation of methane by oxygen at moderate temperatures. A trace amount of acetone is photolyzed at 193 nm a prompt source of methyl radicals in methane-oxygen mixtures. Details of the proposed mechanism are discussed as well as application of the technique to technologies for methane conversion to transportable fuels such as methanol. 15 refs., 6 figs.

Baughcum, S.L.; Oldenborg, R.C.; Danen, W.C.; Streit, G.E.; Rofer, C.

1986-01-01T23:59:59.000Z

65

Comment on "Fission Mass Widths in $^{19}$F + $^{232}$Th, $^{16}$O + $^{235,238}$ U reactions at near barrier energies  

E-Print Network (OSTI)

A critical re-analysis of the experimental data to reject transfer fission component did not change the fragment mass widths and hence the conclusion regarding abrupt rise in mass widths with decreasing energy around Coulomb barrier remains unchanged

T. K. Ghosh; P. Bhattacharya

2005-05-15T23:59:59.000Z

66

A search for inverse fission of uranium  

SciTech Connect

There is a long-term interest in running the fission reaction backward, i.e., studying the 'inverse fission' of uranium. The recent availability of beams of n-rich fission fragments has stimulated interest in this endeavor. The purpose is to search for inverse fission in the reactions {sup 124,132}Sn + {sup 100}Mo. In the {sup 124}Sn + {sup 100}Mo reaction, evaporation residues were searched for using in-beam detection of evaporation residues, in-beam {alpha} spectroscopy, and post-irradiation {alpha} spectroscopy, while in the {sup 132}Sn + {sup 100}Mo reaction, the evaporation residue {sup 230}U was searched for using post-irradiation {alpha} spectroscopy. No evidence for the occurrence of the inverse fission reactions was found. The upper-limit cross section for the latter reaction is {approx}550 {mu}b, while the experimental upper-limit cross section for the former reaction is about 21{sup -21}{sup +38} nb. The intensity of suitable radioactive beams is not high enough at present to detect inverse fission. For the {sup 124}Sn + {sup 100}Mo reaction, the observed upper limits are below the estimates of current models for these reactions, probably due to fusion hindrance.

Yanez, R [Oregon State University, Corvallis; Loveland, Walter [Oregon State University; Beckerman, J. [Oregon State University, Corvallis; Leonard, M. [Oregon State University, Corvallis; Pettersson, G. [Oregon State University, Corvallis; Gross, Carl J [ORNL; Shapira, Dan [ORNL; Liang, J Felix [ORNL; Kohley, Zachary W [ORNL; Varner Jr, Robert L [ORNL

2012-01-01T23:59:59.000Z

67

Fission measurements with PPAC detectors using a coincidence technique  

Science Conference Proceedings (OSTI)

A fission detection setup based on Parallel Plate Avalanche Counters (PPAC) has been constructed and used at the CERN n-TOF facility. The setup takes advantage of the coincidence detection of both fission fragments to discriminate the background reactions produced by high energy neutrons and it allows obtaining neutron-induced fission cross section up to 1 GeV. (authors)

Paradela, C.; Duran, I.; Tarrio, D. [Universidad de Santiago de Compostela (Spain); Audouin, L.; Tassan-Got, L.; Stephan, C. [Inst. de Physique Nucleaire d'Orsay (France)

2011-07-01T23:59:59.000Z

68

Isoscaling behavior in the Fission Dynamics  

E-Print Network (OSTI)

The fission processes of $^{112}$Sn + $^{112}$Sn and $^{116}$Sn + $^{116}$Sn are simulated with the combination of the Langevin equation and the statistical decay model. The masses of two fission fragments are given by assuming the process of symmetric fission or asymmetric fission by the Monte Carlo sampling with the Gaussian probability distribution. From the analysis to the isotopic/isotonic ratios of the fission fragments from both reactions, the isoscaling behavior has been observed and investigated in details. Isoscaling parameters $\\alpha$ and $\\beta$ are extracted as a function of the charge number and neutron number, respectively, in different width of the sampling Gaussian probability distribution. It seems that $\\alpha$ is sensitive to the width of fission probability distribution of the mass asymmetrical parameter but $\\beta$ is not. Both $\\alpha$ and $\\beta$ drop with the increasing of beam energy and the reduced friction parameter.

Y. G. Ma; K. Wang; X. Z. Cai; J. G. Chen; J. H. Chen; D. Q. Fang; W. Guo; C. W. Ma; G. L. Ma; W. Q. Shen; Q. M. Su; W. D. Tian; Y. B. Wei; T. Z. Yan; C. Zhong; X. F. Zhou; J. X. Zuo

2004-12-09T23:59:59.000Z

69

Fission Barriers of Compound Superheavy Nuclei  

E-Print Network (OSTI)

The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work, we investigate the isentropic ...

Sheikh, J. A.

70

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

Science Conference Proceedings (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

71

Interplanetary mission fission  

NLE Websites -- All DOE Office Websites (Extended Search)

A new fission experiment demonstrates the viability of a small nuclear reactor to power solar-system-exploring spacecraft. July 15, 2013 Interplanetary mission fission Artist's...

72

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

SciTech Connect

We describe a novel electrochemical branched-DNA (bDNA) assay for polymerase chain reaction (PCR)-free detection and quantification of p185 BCR-ABL leukemia fusion transcript in the population of messenger RNA (mRNA) extracted from cell lines. The bDNA amplifier carrying high loading of alkaline phosphatase (ALP) tracers was used to amplify targets signal. The targets were captured on microplate well surfaces through cooperative sandwich hybridization prior to the labeling of bDNA. The activity of captured ALP was monitored by square-wave voltammetric (SWV) analysis of the electroactive enzymatic product in the presence of 1-napthyl-phosphate. The specificity and sensitivity of assay enabled direct detection of target transcript in as little as 4.6 ng mRNA without PCR amplification. In combination with the use of a well-quantified standard, the electrochemical bDNA assay was capable of direct use for a PCR-free quantitative analysis of target transcript in total mRNA population. The approach thus provides a simple, sensitive, accurate and quantitative tool alternate to the RQ-PCR for early disease diagnosis.

Lee, Ai Cheng; Dai, Ziyu; Chen, Baowei; Wu, Hong; Wang, Jun; Zhang, Aiguo; Zhang, Lurong; Lim, Tit-Meng; Lin, Yuehe

2008-12-01T23:59:59.000Z

73

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

2013-08-23T23:59:59.000Z

74

Fission properties of the BCPM functional  

E-Print Network (OSTI)

We explore the properties of the Barcelona Catania Paris Madrid (BCPM) energy density functional concerning fission dynamics. Potential energy surfaces as well as collective inertias relevant in the fission process are computed for several nuclei where experimental data exists. Inner and outer barrier heights as well as fission isomer excitation energies are reproduced quite well in all the cases. The spontaneous fission half lives $t_{\\textrm{\\textrm{SF}}}$ are also computed using the standard semiclassical approach and the results are compared with the experimental data. A reasonable agreement with experiment is found over a range of 27 orders of magnitude but the theoretical predictions suffer from large uncertainties associated to the values of the parameters entering the spontaneous fission half life formula. The impact that increasing the pairing correlations strengths has in the spontaneous fission half lives is analyzed and found to be large in all the nuclei considered. Given the satisfactory description of the trend of fission properties with mass number we explore the fission properties of the even-even uranium isotope chain from $^{226}$U to $^{282}$U. Very large half lives are found when getting close to neutron number N=184.

Samuel A. Giuliani; Luis M. Robledo

2013-05-01T23:59:59.000Z

75

Transient effects in fission evidenced from new experimental signatures  

E-Print Network (OSTI)

A new experimental approach is introduced to investigate the relaxation of the nuclear deformation degrees of freedom. Highly excited fissioning systems with compact shapes and low angular momenta are produced in peripheral relativistic heavy-ion collisions. Both fission fragments are identified in atomic number. Fission cross sections and fission-fragment element distributions are determined as a function of the fissioning element. From the comparison of these new observables with a nuclear-reaction code a value for the transient time is deduced.

B. Jurado; C. Schmitt; K. -H. Schmidt; J. Benlliure; T. Enqvist; A. R. Junghans; A. Kelic; F. Rejmund

2004-01-13T23:59:59.000Z

76

The Direct Observation of Secondary Radical Chain Chemistry in the Heterogeneous Reaction of Chlorine Atoms with Submicron Squalane Droplets  

E-Print Network (OSTI)

the Heterogeneous Reaction of Chlorine Atoms with Submicronflow tube reactor in which chlorine atoms are produced byindustrialized areas. 3 Chlorine atoms can be formed by the

Liu, Chen-Lin

2012-01-01T23:59:59.000Z

77

Development of polymerase chain reaction primer sets for diagnosis of Lyme disease and for species-specific identification of Lyme disease isolates by 16S rRNA signature nucleotide analysis  

E-Print Network (OSTI)

polymerase chain reaction primer sets for diagnosis of Lyme disease and for species-specific identification of Lyme disease isolates by 16S rRNA signature nucleotide analysis.

R T Marconi; C F Garon; Richard T. Marconi; Claude; F. Garon

1992-01-01T23:59:59.000Z

78

A New Method of Prompt Fission Neutron Energy Spectrum Unfolding  

Science Conference Proceedings (OSTI)

The prompt neutron emission in spontaneous fission of 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 252 Cf (sf) reaction is one of the main references for nuclear data

O. V. Zeynalova; Sh. Zeynalov; F.?J. Hambsch; S. Oberstedt

2010-01-01T23:59:59.000Z

79

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

Science Conference Proceedings (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

80

Fission Matrix Capability for MCNP Monte Carlo  

Science Conference Proceedings (OSTI)

In a Monte Carlo criticality calculation, before the tallying of quantities can begin, a converged fission source (the fundamental eigenvector of the fission kernel) is required. Tallies of interest may include powers, absorption rates, leakage rates, or the multiplication factor (the fundamental eigenvalue of the fission kernel, k{sub eff}). Just as in the power iteration method of linear algebra, if the dominance ratio (the ratio of the first and zeroth eigenvalues) is high, many iterations of neutron history simulations are required to isolate the fundamental mode of the problem. Optically large systems have large dominance ratios, and systems containing poor neutron communication between regions are also slow to converge. The fission matrix method, implemented into MCNP[1], addresses these problems. When Monte Carlo random walk from a source is executed, the fission kernel is stochastically applied to the source. Random numbers are used for: distances to collision, reaction types, scattering physics, fission reactions, etc. This method is used because the fission kernel is a complex, 7-dimensional operator that is not explicitly known. Deterministic methods use approximations/discretization in energy, space, and direction to the kernel. Consequently, they are faster. Monte Carlo directly simulates the physics, which necessitates the use of random sampling. Because of this statistical noise, common convergence acceleration methods used in deterministic methods do not work. In the fission matrix method, we are using the random walk information not only to build the next-iteration fission source, but also a spatially-averaged fission kernel. Just like in deterministic methods, this involves approximation and discretization. The approximation is the tallying of the spatially-discretized fission kernel with an incorrect fission source. We address this by making the spatial mesh fine enough that this error is negligible. As a consequence of discretization we get a spatially low-order kernel, the fundamental eigenvector of which should converge faster than that of continuous kernel. We can then redistribute the fission bank to match the fundamental fission matrix eigenvector, effectively eliminating all higher modes. For all computations here biasing is not used, with the intention of comparing the unaltered, conventional Monte Carlo process with the fission matrix results. The source convergence of standard Monte Carlo criticality calculations are, to some extent, always subject to the characteristics of the problem. This method seeks to partially eliminate this problem-dependence by directly calculating the spatial coupling. The primary cost of this, which has prevented widespread use since its inception [2,3,4], is the extra storage required. To account for the coupling of all N spatial regions to every other region requires storing N{sup 2} values. For realistic problems, where a fine resolution is required for the suppression of discretization error, the storage becomes inordinate. Two factors lead to a renewed interest here: the larger memory available on modern computers and the development of a better storage scheme based on physical intuition. When the distance between source and fission events is short compared with the size of the entire system, saving memory by accounting for only local coupling introduces little extra error. We can gain other information from directly tallying the fission kernel: higher eigenmodes and eigenvalues. Conventional Monte Carlo cannot calculate this data - here we have a way to get new information for multiplying systems. In Ref. [5], higher mode eigenfunctions are analyzed for a three-region 1-dimensional problem and 2-dimensional homogenous problem. We analyze higher modes for more realistic problems. There is also the question of practical use of this information; here we examine a way of using eigenmode information to address the negative confidence interval bias due to inter-cycle correlation. We apply this method mainly to four problems: 2D pressurized water reactor (PWR) [6],

Carney, Sean E. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory

2012-09-05T23:59:59.000Z

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

Fission Matrix Capability for MCNP Monte Carlo  

SciTech Connect

In a Monte Carlo criticality calculation, before the tallying of quantities can begin, a converged fission source (the fundamental eigenvector of the fission kernel) is required. Tallies of interest may include powers, absorption rates, leakage rates, or the multiplication factor (the fundamental eigenvalue of the fission kernel, k{sub eff}). Just as in the power iteration method of linear algebra, if the dominance ratio (the ratio of the first and zeroth eigenvalues) is high, many iterations of neutron history simulations are required to isolate the fundamental mode of the problem. Optically large systems have large dominance ratios, and systems containing poor neutron communication between regions are also slow to converge. The fission matrix method, implemented into MCNP[1], addresses these problems. When Monte Carlo random walk from a source is executed, the fission kernel is stochastically applied to the source. Random numbers are used for: distances to collision, reaction types, scattering physics, fission reactions, etc. This method is used because the fission kernel is a complex, 7-dimensional operator that is not explicitly known. Deterministic methods use approximations/discretization in energy, space, and direction to the kernel. Consequently, they are faster. Monte Carlo directly simulates the physics, which necessitates the use of random sampling. Because of this statistical noise, common convergence acceleration methods used in deterministic methods do not work. In the fission matrix method, we are using the random walk information not only to build the next-iteration fission source, but also a spatially-averaged fission kernel. Just like in deterministic methods, this involves approximation and discretization. The approximation is the tallying of the spatially-discretized fission kernel with an incorrect fission source. We address this by making the spatial mesh fine enough that this error is negligible. As a consequence of discretization we get a spatially low-order kernel, the fundamental eigenvector of which should converge faster than that of continuous kernel. We can then redistribute the fission bank to match the fundamental fission matrix eigenvector, effectively eliminating all higher modes. For all computations here biasing is not used, with the intention of comparing the unaltered, conventional Monte Carlo process with the fission matrix results. The source convergence of standard Monte Carlo criticality calculations are, to some extent, always subject to the characteristics of the problem. This method seeks to partially eliminate this problem-dependence by directly calculating the spatial coupling. The primary cost of this, which has prevented widespread use since its inception [2,3,4], is the extra storage required. To account for the coupling of all N spatial regions to every other region requires storing N{sup 2} values. For realistic problems, where a fine resolution is required for the suppression of discretization error, the storage becomes inordinate. Two factors lead to a renewed interest here: the larger memory available on modern computers and the development of a better storage scheme based on physical intuition. When the distance between source and fission events is short compared with the size of the entire system, saving memory by accounting for only local coupling introduces little extra error. We can gain other information from directly tallying the fission kernel: higher eigenmodes and eigenvalues. Conventional Monte Carlo cannot calculate this data - here we have a way to get new information for multiplying systems. In Ref. [5], higher mode eigenfunctions are analyzed for a three-region 1-dimensional problem and 2-dimensional homogenous problem. We analyze higher modes for more realistic problems. There is also the question of practical use of this information; here we examine a way of using eigenmode information to address the negative confidence interval bias due to inter-cycle correlation. We apply this method mainly to four problems: 2D pressurized water reactor (PWR) [6],

Carney, Sean E. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory

2012-09-05T23:59:59.000Z

82

Complex fission phenomena  

E-Print Network (OSTI)

Complex fission phenomena are studied in a unified way. Very general reflection asymmetrical equilibrium (saddle point) nuclear shapes are obtained by solving an integro-differential equation without being necessary to specify a certain parametrization. The mass asymmetry in binary cold fission of Th and U isotopes is explained as the result of adding a phenomenological shell correction to the liquid drop model deformation energy. Applications to binary, ternary, and quaternary fission are outlined.

D. N. Poenaru; R. A. Gherghescu; W. Greiner

2004-04-09T23:59:59.000Z

83

Fission Barriers of Compound Superheavy Nuclei  

E-Print Network (OSTI)

The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work, we investigate the isentropic fission barriers by means of the self-consistent nuclear density functional theory. The relationship between isothermal and isentropic descriptions is demonstrated. Calculations have been carried out for $^{264}$Fm, $^{272}$Ds, $^{278}$112, $^{292}$114, and $^{312}$124. For nuclei around $^{278}$112 produced in "cold fusion" reactions, we predict a more rapid decrease of fission barriers with excitation energy as compared to the nuclei around $^{292}$114 synthesized in "hot fusion" experiments. This is explained in terms of the difference between the ground-state and saddle-point temperatures. The effect of the particle gas is found to be negligible in the range of temperatures studied.

J. C. Pei; W. Nazarewicz; J. A. Sheikh; A. K. Kerman

2009-01-07T23:59:59.000Z

84

Electron-capture delayed fission properties of 244Es  

Science Conference Proceedings (OSTI)

Electron-capture delayed fission was observed in {sup 244}Es produced via the {sup 237}Np({sup 12}C,5n){sup 244}Es reaction at 81 MeV (on target) with a production cross section of 0.31{+-}0.12 {micro}b. The mass-yield distribution of the fission fragments is highly asymmetric. The average preneutron-emission total kinetic energy of the fragments was measured to be 186{+-}19 MeV. Based on the ratio of the number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 244}Cf (100% {alpha} branch), the probability of delayed fission was determined to be (1.2{+-}0.4) x 10{sup -4}. This value for the delayed fission probability fits the experimentally observed trend of increasing delayed fission probability with increasing Q value for electron-capture.

Shaughnessy, Dawn A.; Gregorich, Kenneth E.; Adams, Jeb L.; Lane, Michael R.; Laue, Carola A.; Lee, Diana M.; McGrath, Christopher A.; Ninov, Victor; Patin, Joshua B.; Strellis, Dan A.; Sylwester, Eric R.; Wilk, Philip A.; Hoffman, Darleane C.

2001-03-16T23:59:59.000Z

85

Our 50-year odyssey with fission: Summary  

Science Conference Proceedings (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

86

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

87

Sharp change over from compound nuclear fission to shape dependent quasi fission  

E-Print Network (OSTI)

Fission fragment mass distribution has been measured from the decay of $^{246}$Bk nucleus populating via two entrance channels with slight difference in mass asymmetries but belonging on either side of the Businaro Gallone mass asymmetry parameter. Both the target nuclei were deformed. Near the Coulomb barrier, at similar excitation energies the width of the fission fragment mass distribution was found to be drastically different for the $^{14}$N + $^{232}$Th reaction compared to the $^{11}$B + $^{235}$U reaction. The entrance channel mass asymmetry was found to affect the fusion process sharply.

T. K. Ghosh; K. Banerjee; C. Bhattacharya; S. Bhattacharya; S. Kundu; P. Mali; J. K. Meena; G. Mukherjee; S. Mukhopadhyay; T. K. Rana; P. Bhattacharya; K. S. Golda

2008-09-17T23:59:59.000Z

88

Fission Energy Release for 16 Fissioning Nuclides  

Science Conference Proceedings (OSTI)

This report describes results of a study of fission energy releases and the components of this energy. Energy releases for primary isotopes, for which relatively good experimental quantities exist, were determined by a combination of mass-defect systematics and least-square fits with the experimental data. Only the systematic study was carried out for the remaining isotopes.

1981-03-01T23:59:59.000Z

89

Overview of Fission Safety for Laser ICF Fission Energy  

Science Conference Proceedings (OSTI)

Laser Fusion-Fission Hybrid / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)

Per F. Peterson; Edward Blandford; Christhian Galvez

90

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

91

Liquid uranium alloy-helium fission reactor  

SciTech Connect

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

92

Experimental Progress Report--Modernizing the Fission Basis  

Science Conference Proceedings (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 (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

93

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

94

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

95

Applications of Event-by-Event Fission Modeling with FREYA  

Science Conference Proceedings (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. We first discuss the present status of FREYA, which has now been extended to include spontaneous fission. Concentrating on {sup 239}Pu(n{sub th},f), {sup 240}Pu(sf) and {sup 252}Cf(sf), 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 suggest novel fission observables that could be measured with modern detectors.

Vogt, R; Randrup, J

2011-09-16T23:59:59.000Z

96

Fission Detection Using the Associated Particle Technique  

Science Conference Proceedings (OSTI)

A beam of tagged 14 MeV neutrons from the deuterium-tritium (DT) reaction is used to induce fission in a target composed of depleted uranium. The generator yield is 107 neutrons/second radiated into a 4? solid angle. Two 4 in.×4 in. NaI detectors are used for gamma-ray detection. The fission process is known to produce multiple gamma-rays and neutrons. Triple coincidences (?-?-?) are measured as a function of neutron flight time up to 90 ns after fission, where the ?-particle arises from the DT reaction. A sudden increase in the triple coincidence rate at the location of the material is used to localize and detect fission in the interrogated target. Comparisons are made with experiment runs where lead, tungsten, and iron were used as target materials. The triple coincidence response profile from depleted uranium is noted to be different to those observed from the other target materials. The response from interrogation targets composed of fissile material is anticipated to be even more unique than that observed from depleted uranium.

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

2008-09-18T23:59:59.000Z

97

The Fission of Thorium with Alpha Particles  

E-Print Network (OSTI)

fissi on distribution of fission of thor ium v'jith alphaafter the discovery of fission, Meitner and Bretscher andin the distribution of fission products in the two . !

Newton, Amos S.

2010-01-01T23:59:59.000Z

98

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

2010-07-07T23:59:59.000Z

99

Mirror fusion--fission hybrids  

SciTech Connect

The fusion-fission concept and the mirror fusion-fission hybrid program are outlined. Magnetic mirror fusion drivers and blankets for hybrid reactors are discussed. Results of system analyses are presented and a reference design is described.

Lee, J.D.

1978-05-01T23:59:59.000Z

100

Radiochemistry of the fission products  

SciTech Connect

This paper discusses the historical aspects of the radiochemistry of fission products. 20 figs., 2 tabs. (LSP)

Steinberg, E.P.

1988-01-01T23:59:59.000Z

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.


101

Process for treating fission waste  

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, Charles A. (Kennewick, WA); Wick, Oswald J. (Richland, WA)

1983-01-01T23:59:59.000Z

102

Microscopic Description of Induced Fission  

E-Print Network (OSTI)

Selected aspects of the description of neutron-induced fission in 240Pu in the framework of the nuclear energy density functional theory at finite temperature are presented. In particular, we discuss aspects pertaining to the choice of thermodynamic state variables, the evolution of fission barriers as function of the incident neutron energy, and the temperatures of the fission fragments.

N. Schunck

2013-02-22T23:59:59.000Z

103

In vivo footprinting of the human [alpha]-globin locus upstream regulatory element by guanine and adenine ligation-mediated polymerase chain reaction  

SciTech Connect

A major regulatory element required for expression of the human [alpha]-globin genes is located 40 kb upstream of the embryonic [zeta]-globin gene. To understand how this and other locus control region (LCR) elements contribute to high-level expression in erythroid cells, we have performed high-resolution, in vivo dimethyl sulfate footprinting. In addition, we have modified the dimethyl sulfate-based ligation-mediated polymerase chain reaction in vivo footprinting procedure to permit the assessment of interactions at guanine and adenine residues, rather than guanines alone. In vivo footprinting of the human [alpha]-LCR element carried on chromosome 16 in a mouse erythroleukemia cell environment revealed protein occupancy at GATA-1, AP-1/NF-E2, and CACC/GGTGG motifs, specific differences compared with in vitro protein binding, and distinct changes in one region upon dimethyl sulfoxide-induced cellular maturation. No protein contacts were detected in nonexpressing hepatoma cells. In addition, we have demonstrated that two AP-1 motifs in the [alpha]-LCR element which are occupied in vivo bind purified mouse NF-E2 protein in vitro. Our data suggest that three proteins, GATA-1, NF-E2, and unknown CACC/GGTGG factors, are minimally required as DNA-binding proteins for the function of LCR-like elements. The juxtaposition and interaction of these factors with each other, and with accessory proteins not directly in contact with DNA, are likely to account for the relative position independence of the upstream globin regulatory elements. 39 refs., 6 figs.

Strauss, E.C.; Andrews, N.C.; Orkin, S.H.; Higgs, D.R. (Howard Hughes Medical Institute, Boston, MA (United States))

1992-05-01T23:59:59.000Z

104

I. Nuclear Production Reaction and Chemical Isolation Procedure for 240Am II. New Superheavy Element Isotopes: 242Pu(48Ca,5n)285-114  

E-Print Network (OSTI)

material and common nuclear fission products in the 1 eV –of destroying long-lived nuclear fission products by neutronFlerov Laboratory of Nuclear Reactions Fission product Focal

Ellison, Paul Andrew

2011-01-01T23:59:59.000Z

105

Radiation Detection from Fission  

SciTech Connect

This report briefly describes the neutrons and gamma rays emitted in fission, briefly discusses measurement methods, briefly discusses sources and detectors relevant to detection of shielded HEU in sealand containers, and lists the measurement possibilities for the various sources. The brief descriptions are supplemented by reference.

Mihalczo, J.

2004-11-17T23:59:59.000Z

106

NEUTRONIC REACTION SYSTEM  

DOE Patents (OSTI)

A nuclear reactor system is described for breeding fissionable material, including a heat-exchange tank, a high- and a low-pressure chamber therein, heat- exchange tubes connecting these chambers, a solution of U/sup 233/ in heavy water in a reaction container within the tank, a slurry of thorium dioxide in heavy water in a second container surrounding the first container, an inlet conduit including a pump connecting the low pressure chamber to the reaction container, an outlet conduit connecting the high pressure chamber to the reaction container, and means of removing gaseous fission products released in both chambers. (AEC)

Wigner, E.P.

1963-09-01T23:59:59.000Z

107

Proton-induced fission of heavy nuclei at intermediate energies  

E-Print Network (OSTI)

The intermediate energy proton-induced fission of 241Am, 238$U and 237$Np is studied. The inelastic interactions of protons and heavy nuclei are described by a CRISP model, in which the reaction proceeds in two steps. The first one corresponds fast cascade, where a series of individual particle-particle collisions occurs within the nucleus. It leaves a highly excited cascade residual nucleus, assumed to be in thermal equilibrium. Subsequently, in the second step the excited nucleus releases its energy by evaporation of neutrons and light charged particles as well. Both the symmetric and asymmetric fission are regarded, and the fission probabilities are obtained from CRISP code calculations, by means of statistical weighting factors. The fission cross sections, the fissility of the fissioning nuclei, and the number of nucleons lost by the target - before and after fission - are calculated and compared to experiments for 660 MeV protons incident on 241Am, 238$U and 237$Np. Some of the model predictions are in full compliance to the experiments. We conclude that our two step model provides a reasonable description of the medium energy proton-induced fission.

A. Deppman; E. Andrade-II; V. Guimaraes; G. S. Karapetyan; A. R. Balabekyan; N. A. Demekhina

2013-02-09T23:59:59.000Z

108

A New Method of Prompt Fission Neutron Energy Spectrum Unfolding  

Science Conference Proceedings (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

109

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

SciTech Connect

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

110

The role of chemical reactions in the Chernobyl accident  

SciTech Connect

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

111

on Physics of Nuclear Fission,  

E-Print Network (OSTI)

spin-tensor of orientation Experimental data on angular distributions of ? rays emitted from binary and ternary spontaneous fission of 252 Cf are analyzed. Their difference indicates that the alignment of fragments is higher in ternary fission than in binary one. The consequences of possible relation between the mechanism of ternary fission and the excitation of collective modes during the saddle- to-scission stage are discussed. ii

unknown authors

1994-01-01T23:59:59.000Z

112

Experimental Progress Report--Modernizing the Fission Basis  

SciTech Connect

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

113

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

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

114

A REVIEW OF NUCLEAR FISSION. PART ONE. FISSION PHENOMENA AT LOW ENERGY. Revised Edition  

SciTech Connect

The discovery of fission is described, and fission theory is outlined. The probability of fission is discussed. Distribution of mass and nuclear charge in fission is considered. Measurements of the kinetic energy of fission fragments are described. The emission of prompt neutrons, delayed neutrons, and gamma rays in fission is discussed. (M.C.G.)

Hyde, E.K.

1962-04-01T23:59:59.000Z

115

FISSION PRODUCT TRAPS FOR USE IN HIGH-TEMPERATURE GAS-COOLED GRAPHITE REACTORS  

SciTech Connect

A proposal is given of an approach to a fission-product trapping system which appears feasible on the basis of thermodynamic and other data available. Reactor and trapping conditions are outlined. The half-lives, fission yields, and volatility of the fission products of interest are described. To provide the most effective retention at elevated temperatures, two types of reagents are required: a highly electropositive metal that will not melt or appreciably vaporize and which will form stable non-volatile compounds with non-metallic or near non-metallic fission products; and a reagent to provide a highly electronegative element to form stable, non-volatile compounds with metallic fission products. Thermodynamic properties are included for compounds formed by reactions between the fission products and the trapping reagents. (B.O.G.)

Zumwalt, L.R.

1958-03-13T23:59:59.000Z

116

Fission-suppressed fusion breeder on the thorium cycle and nonproliferation  

Science Conference Proceedings (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 fusion /Pinput=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 233U with 238U. Also nonproliferation is enhanced in typical fission-suppressed designs by generating up to 0.05 232U atoms for each 233U atom produced from thorium

R. W. Moir

2012-01-01T23:59:59.000Z

117

THE SOGGY SADDLE THEORY OF FISSION  

E-Print Network (OSTI)

SOGGY SADDLE THEORY OF FISSION L.G. Moretto and G. GuarinoMIWW The soggy saddle theory of fission L.6. Moretto and G.transition state theory of fission is generalized to allow

Moretto, L.G.

2010-01-01T23:59:59.000Z

118

The Fission of thorium with Alpha Particles  

E-Print Network (OSTI)

cm 2 FIG. 2 YIELD OF SOME FISSION PRODUCTS FROM THORIUM +-in aalou.latlnl~ I tha fission yield ot tlla 2.3;; dnyci~S~~SIO NASS HO. FIG. I FISSION YIELD SPECTRUM OF THORIUM

Newton, Amos S.

2010-01-01T23:59:59.000Z

119

FISSION OF GOLD BY CARBON IONS  

E-Print Network (OSTI)

private communication. The fission-barrier calculations arein the systematics of spontaneous-fission half lives, W. J.1955). H. Marshall Blann, Fission of Gold with 112-Mev C

Gordon, Glen E.; Larsh, Almon E.; Sikkeland, Torbjorn; Seaborg, Glenn T.

2008-01-01T23:59:59.000Z

120

Post-scission fission theory: Neutron emission in fission  

Science Conference Proceedings (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

Note: This page contains sample records for the topic "fission chain reaction" from the National Library of EnergyBeta (NLEBeta).
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121

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

2013-11-11T23:59:59.000Z

122

Fission modes of mercury isotopes  

E-Print Network (OSTI)

Background: Recent experiments on beta-delayed fission in the mercury-lead region and the discovery of asym- metric fission in 180 Hg [1] have stimulated theoretical interest in the mechanism of fission in heavy nuclei. Purpose: We study fission modes and fusion valleys in 180 Hg and 198 Hg to reveal the role of shell effects in pre-scission region and explain the experimentally observed fragment mass asymmetry and its variation with A. Methods: We use the self-consistent nuclear density functional theory employing Skyrme and Gogny energy density functionals. Results: The potential energy surfaces in multi-dimensional space of collective coordinates, including elongation, triaxiality, reflection-asymmetry, and necking, are calculated for 180 Hg and 198 Hg. The asymmetric fission valleys - well separated from fusion valleys associated with nearly spherical fragments - are found in in both cases. The density distributions at scission configurations are studied and related to the experimentally observed mass splits. Conclusions: The energy density functionals SkM\\ast and D1S give a very consistent description of the fission process in 180 Hg and 198 Hg. We predict a transition from asymmetric fission in 180 Hg towards more symmetric distribution of fission fragments in 198 Hg. For 180 Hg, both models yield 100 Ru/80 Kr as the most probable split. For 198 Hg, the most likely split is 108 Ru/90 Kr in HFB-D1S and 110 Ru/88 Kr in HFB-SkM\\ast.

M. Warda; A. Staszczak; W. Nazarewicz

2012-05-25T23:59:59.000Z

123

Fission Modes of Mercury Isotopes  

Science Conference Proceedings (OSTI)

Background: Recent experiments on -delayed fission in the mercury-lead region and the discovery of asymmetric fission in 180Hg [A. N. Andreyev et al., Phys. Rev. Lett. 105, 252502 (2010)] have stimulated theoretical interest in the mechanism of fission in heavy nuclei. Purpose: We study fission modes and fusion valleys in 180Hg and 198Hg to reveal the role of shell effects in the prescission region and explain the experimentally observed fragment mass asymmetry and its variation with A. Methods: We use the self-consistent nuclear density functional theory employing Skyrme and Gogny energy density functionals. Results: The potential energy surfaces in multidimensional space of collective coordinates, including elongation, triaxiality, reflection-asymmetry, and necking, are calculated for 180Hg and 198Hg. The asymmetric fission valleys well separated from fusion valleys associated with nearly spherical fragments are found in both cases. The density distributions at scission configurations are studied and related to the experimentally observed mass splits. Conclusions: The energy density functionals SkM and D1S give a very consistent description of the fission process in 180Hg and 198Hg. We predict a transition from asymmetric fission in 180Hg toward a more symmetric distribution of fission fragments in 198Hg. For 180Hg, both models yield 100Ru/80Kr as the most probable split. For 198Hg, the most likely split is 108Ru/90Kr in HFB-D1S and 110Ru/88Kr in HFB-SkM .

Warda, M. [Maria Curie-Sk?odowska University-Poland; Staszczak, A. [Maria Curie-Sklodowska University; Nazarewicz, Witold [UTK/ORNL/University of Warsaw

2012-01-01T23:59:59.000Z

124

Fission throughout the periodic table  

Science Conference Proceedings (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

125

TREATMENT OF FISSION PRODUCT WASTE  

DOE Patents (OSTI)

A pyrogenic method of separating nuclear reactor waste solutions containing aluminum and fission products as buring petroleum coke in an underground retort, collecting the easily volatile gases resulting as the first fraction, he uminum chloride as the second fraction, permitting the coke bed to cool and ll contain all the longest lived radioactive fission products in greatly reduced volume.

Huff, J.B.

1959-07-28T23:59:59.000Z

126

FISSION OF GOLD BY CARBON IONS  

E-Print Network (OSTI)

and J. R. Huizenga, Nuclear Fission (to be published inHeavy-lon-Induced Nuclear Fission, (to be published in Proc.

Gordon, Glen E.; Larsh, Almon E.; Sikkeland, Torbjorn; Seaborg, Glenn T.

2008-01-01T23:59:59.000Z

127

Direct measurement of the {sup 11}C({alpha},p){sup 14}N reaction at CRIB: A path from pp-chain to CNO  

SciTech Connect

We determined the total reaction rate of the {sup 11}C({alpha},p){sup 14}N reaction relevant to the nucleosynthesis in explosive hydrogen-burning stars. The measurement was performed by means of the thick target method in inverse kinematics with {sup 11}C RI beams. We performed the identification of the ground-state transition and excited-state transitions using time-of-flight information for the first time.

Hayakawa, S.; Kubono, S.; Kahl, D.; Yamaguchi, H.; Binh, D. N.; Hashimoto, T.; Wakabayashi, Y.; He, J. J.; Iwasa, N.; Kato, S.; Komatsubara, T.; Kwon, Y. K.; Teranishi, T.; Wanajo, S. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare (Italy); Nishina Center, RIKEN (Japan); Center for Nuclear Study, University of Tokyo (Japan)

2012-11-20T23:59:59.000Z

128

More on the term ŤFission?  

NLE Websites -- All DOE Office Websites (Extended Search)

information, and he certainly did. His insight into the origin of the term "fission" expanded greatly on the mere mention I had made of it in the Y-12 history column he...

129

The microscopic theory of fission  

E-Print Network (OSTI)

Fission-fragment properties have been calculated for thermal neutron-induced fission on a $^{239}\\textrm{Pu}$ target, using constrained Hartree-Fock-Bogoliubov calculations with a finite-range effective interaction. A quantitative criterion based on the interaction energy between the nascent fragments is introduced to define the scission configurations. The validity of this criterion is benchmarked against experimental measurements of the kinetic energies and of multiplicities of neutrons emitted by the fragments.

W. Younes; D. Gogny

2009-10-09T23:59:59.000Z

130

FISSION YIELDS AND LIFETIMES FOR MUON INDUCED FISSION IN 235U AND 238U  

E-Print Network (OSTI)

University of California. FISSION YIELDS AL\\JD LIFETIMES FORfor his assistance in the fission chamber calibrations andCl8 (1978) 1452. Table 1 Fission yields yf Nucleus 23su 23Su

Ahmad, S.

2012-01-01T23:59:59.000Z

131

Fail-safe source-driven fission and fusion-fission hybrid reactor configurations.  

E-Print Network (OSTI)

??A source-driven nuclear reactor configuration with a unity infinite medium multiplication factor fission core (1k??), is investigated for both fission and fusion-fission hybrid systems. Suchaconfiguration… (more)

Singh, Monish

2013-01-01T23:59:59.000Z

132

Investigation of induced fission of natPb by accelerated 7Li ions  

E-Print Network (OSTI)

The cross-section of the natPb binary fission, induced by 7Li ions at 245 MeV energy, was measured and the fission product cross-sections studied by means of activation analysis in the off-line regimen. The analysis of charge and mass distributions of fission products allows to calculate the fission cross-section. The recoil technique ("thick target- thick catcher"), based on the two step model mathematical formalism, is used for the determination of the kinematical characteristics of reaction products. The data concerning transferred linear momentum provides information on the initial projectile-target interaction, and is compared to measurements of the proton-induced fission.

N. A. Demekhina; G. S. Karapetyan; V. Guimaraes

2013-02-02T23:59:59.000Z

133

Temperature-Dependent Fission Barriers of Superheavy Nuclei  

E-Print Network (OSTI)

The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. We study the temperature-dependent fission barriers by means of the self-consistent nuclear density functional theory. The equivalence of isothermal and isentropic descriptions is demonstrated. The effect of the particle gas is found to be negligible in the range of temperatures studied. Calculations have been carried out for $^{264}$Fm, $^{272}$Ds, $^{278}$112, $^{292}$114, and $^{312}$124. For nuclei around $^{278}$112 produced in "cold fusion" reactions, we predict a more rapid decrease of fission barriers with temperature as compared to the nuclei around $^{292}$114 synthesized in "hot fusion" experiments. This is explained in terms of the difference between the ground-state and fission-barrier temperatures. Our calculations are consistent with the long survival probabilities of the superheavy elements produced in Dubna with th...

Pei, J C; Sheikh-Javid, A; Kerman, A K

2009-01-01T23:59:59.000Z

134

ADIABATICITY CRITERION FOR CHARGE EQUILIBRATION WITH APPLICATION TO FISSION  

E-Print Network (OSTI)

strongly damped nuclear collisions and in fission. This work48, In nuclear collisions and in fission the fluctuations instages of fission and strongly damped nuclear collisions the

Myers, W.D.

2013-01-01T23:59:59.000Z

135

Logging Calibration Models for Fission Neutron Sondes (September...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Logging Calibration Models for Fission Neutron Sondes (September 1981) Logging Calibration Models for Fission Neutron Sondes (September 1981) Logging Calibration Models for Fission...

136

ORNL fission product release tests VI-6  

DOE Green Energy (OSTI)

The ORNL fission product release tests investigate release and transport of the major fission products from high-burnup fuel under LWR accident conditions. The two most recent tests (VI-4 and VI-5) were conducted in hydrogen. In three previous tests in this series (VI-1, VI-2, and VI-3), which had been conducted in steam, the oxidized Zircaloy cladding remained largely intact and acted as a barrier to steam reaction with the UO{sub 2}. Test VI-6 was designed to insure significant oxidation of the UO{sub 2} fuel, which has been shown to enhance release of certain fission products, especially molybdenum and ruthenium. The BR3 fuel specimen used in test VI-6 will be heated in hydrogen to 2300 K; the Zircaloy cladding is expected to melt and runoff at {approximately}2150 K. Upon reaching the 2300 K test temperature, the test atmosphere will be changed to steam, and that temperature will be maintained for 60 min, with the three collection trains being operated for 2-, 18-, and 40-min periods. The releases of {sup 85}Kr and {sup 137}Cs will be monitored continuously throughout the test. Posttest analyses of the material collected on the three trains will provide results on the release and transport of Mo, Ru, Sb, Te, Ba, Ce, and Eu as a function of time at 2300 K. Continuous monitoring of the hydrogen produced during the steam atmosphere period at high temperature will provide a measure of the oxidation rate of the cladding and fuel. Following delays in approval of the safety documentation and in decontamination of the hot cell and test apparatus, test VI-6 will be conducted in late May.

Osborne, M.F.; Lorenz, R.A.; Collins, J.L.; Lee, C.S.

1991-01-01T23:59:59.000Z

137

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

Science Conference Proceedings (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

138

Fission product solvent extraction  

SciTech Connect

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

139

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

140

Fission Cross Section Calculation Using TALYS Based on Two Different Level Density Models  

Science Conference Proceedings (OSTI)

Fission cross sections in statistical model of fission are calculated using one of important parameter such as transmission coefficients. This parameter calculated using optical model parameter and level density. There are several models of level density that can be used to predict fission cross section. They are Constant Temperature Model, Fermi Gas Model, Back-Shifted Fermi Gas Model, and Generalized Superfluid Model. In this work, fission cross section would be calculated using two different model of level density, such as Constant Temperature Model Plus Fermi Gas and Generalized Superfluid Model on Th-232 (n,f) fission reaction. Calculation result from two different model then would be compared with experimental data from ENDF B/VI. Analysis of result would lead to the conclusion of spesific characteristic for each model in every fission cases. This work has became a preliminary study to calculate fission cross section using different set of level density models. Further work will be implemented to calculate similar fission cross section using level density parameter that approximated by Thermal wavelength [see 21].

Kurniadi, R.; Basar, K.; Waris, A. [Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia); Perkasa, Yudha S. [Department of Physics, Jl. Ganesa 10 Bandung 40132 (Indonesia); Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia)

2010-06-22T23:59:59.000Z

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

Entrance-channel dependence of fission transients  

E-Print Network (OSTI)

Fission transients describe the fission rate as it evolves towards the quasistationary value given by Kramers' formula. The nature of fission transients is dependent on the assumed initial distribution of the compound nuclei along the fission coordinate. Although the standard initial assumption of a near-spherical object leads to a transient suppression of the fission rate (fission delay), a moderate initial fissionlike deformation can reduce the magnitude of this suppression. For still larger initial deformations, transient fission enhancements are possible. Examples of this behavior are illustrated via a one-dimensional Langevin simulation. It is argued that the initial conditions are determined by the fusion dynamics and thus are entrance-channel dependent. Transient fission may be considered intermediate between statistical fission and quasifission as the rapid time scale of transient fission may not lead to an equilibrium of the angular and mass-asymmetry coordinates. The relationship between the mean first passage time and the transients are discussed. For temperatures much smaller than the fission barrier, the mean first passage time is independent of the nature of the fission transients if there is no strong competition from evaporation. Thus, fission transients are most important when the evaporation time scale is smaller than, or of the order of, the transient time.

R. J. Charity

2004-06-14T23:59:59.000Z

142

Cranking mass parameters for fission  

E-Print Network (OSTI)

A formalism for semi-adiabatic cranking mass parameters is presented. For the fission process of 234U, the time-dependent pairing equations of motion were used to calculate the excitation energy and to extract values of the cranking inertia. A fission barrier is determined by minimizing the action trajectory in a five dimensional configuration space spanned by elongation, necking, deformations of fragments and mass-asymmetry. The deformation energy is computed in the the frame of the microscopic-macroscopic model. The two center shell model with Woods-Saxon potentials is used in this context. Values of the inertia for excited fissioning systems are reported. A dependence between the cranking mass parameters and the intrinsic excitation energy is evidenced.

M. Mirea; R. C. Bobulescu

2009-09-11T23:59:59.000Z

143

Pair breaking and Coulomb effects in cold fission from thermal neutron induced fission of U 233, U 235 and Pu 239  

E-Print Network (OSTI)

In this paper, the distribution of mass and kinetic energy in the cold region of the thermal neutron induced fission of U 233, U 235 and Pu 239, respectively, is interpreted in terms of nucleon pair-breaking and the Coulomb interaction energy between complementary fragments (Coulomb effect). In order to avoid the erosive consequences of neutron emission, one studies the cold fission regions, corresponding to total kinetic energy (TE) close to the maximum available energy of the reaction (Q). Contrary to expected, in cold fission is not observed high odd-even effect in mass number distribution. Nevertheless, the measured values are compatible with higher odd-even effects on proton or neutron number distribution, respectively. In addition, in cold fission, the minimal total excitation energy (X) is correlated with the Coulomb energy excess, which is defined as the difference between C (the electrostatic interaction energy between complementary fragments taken as spherical in scission configuration) and Q. These...

Montoya, Modesto

2013-01-01T23:59:59.000Z

144

The nucleon phase hypothesis of binary fission  

E-Print Network (OSTI)

The mass distribution of fission fragments of actinide and superheavy nuclei can be explained if a new state of nuclear matter, a nucleon phase, is created in any fission event.

G. Mouze; S. Hachem; C. Ythier

2010-06-21T23:59:59.000Z

145

The nucleon phase hypothesis of binary fission  

E-Print Network (OSTI)

The mass distribution of fission fragments of actinide and superheavy nuclei can be explained if a new state of nuclear matter, a nucleon phase, is created in any fission event.

Mouze, G; Ythier, C

2010-01-01T23:59:59.000Z

146

Quantum efficiency and fission rate in tetracene  

E-Print Network (OSTI)

Using singlet fission in a photovoltaic cell, the theoretical energy conversion efficiency limit is larger than the Shockley-Queisser limit due to two excitons produced with one incident photon. In a singlet fission material, ...

Wu, Tony Chang-Chi

2013-01-01T23:59:59.000Z

147

PRODUCING ENERGY AND RADIOACTIVE FISSION PRODUCTS  

DOE Patents (OSTI)

This patent broadly discloses the production of plutonium by the neutron bombardment of uranium to produce neptunium which decays to plutonium, and the fissionability of plutonium by neutrons, both fast and thermal, to produce energy and fission products.

Segre, E.; Kennedy, J.W.; Seaborg, G.T.

1959-10-13T23:59:59.000Z

148

The Metabolic Properties of the Fission Products and Actinide Elements  

E-Print Network (OSTI)

directly from nuclear fission. Radioactive substances can··free Fission Prodl,wts in the Rat" Natl Nuclear Energy

Hamilton M.D., J.G.

2010-01-01T23:59:59.000Z

149

THE WIDTH OF THE CHARGE DISTRIBUTION IN FISSION  

E-Print Network (OSTI)

strongly damped nuclear collisions or in fission. Since theDistribution in Fission William 0. Myers Nuclear Science

Myers, W.D.

2010-01-01T23:59:59.000Z

150

Neutronics for critical fission reactors and subcritical fission in hybrids  

SciTech Connect

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

151

Nuclear fission in covariant density functional theory  

E-Print Network (OSTI)

The current status of the application of covariant density functional theory to microscopic description of nuclear fission with main emphasis on superheavy nuclei (SHN) is reviewed. The softness of SHN in the triaxial plane leads to an emergence of several competing fission pathes in the region of the inner fission barrier in some of these nuclei. The outer fission barriers of SHN are considerably affected both by triaxiality and octupole deformation.

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

2013-09-12T23:59:59.000Z

152

Axisymmetric Magnetic Mirror Fusion-Fission Hybrid  

Science Conference Proceedings (OSTI)

Fusion-Fission Hybrids and Transmutation / Proceedings of the Fifteenth International Conference on Emerging Nuclear Energy Systems

R. W. Moir; N. N. Martovetsky; A. W. Molvik; D. D. Ryutov; T. C. Simonen

153

Multiple-Coincidence Interrogation of Fissionables  

SciTech Connect

The multiple coincidence technique uses 14.1 MeV neutrons to produce (n, multiple-?) coincidences to detect fissile and fissionable materials. Measurements of n-?-? coincidences with targets of depleted uranium (DU), W, and Pb, show that the counting rate for the DU is substantially above that for the non-fissionables. Also, the data involving prompt neutrons and delayed gammas in the DU time spectra provide a signature for fissionables that is distinct from that of non-fissionables.

J.P. Hurley, R.P. Keegan, J.R. Tinsley, R. Trainham

2009-05-01T23:59:59.000Z

154

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

155

Fission dynamics at low excitation energy  

E-Print Network (OSTI)

The origin of mass asymmetry in the fission of uranium at a low excitation energy is clarified by a trajectory analysis of the Langevin equation. The positions of the peaks in the mass distribution of fission fragments are mainly determined by fission saddle points originating from the shell correction energy. The widths of the peaks, on the other hand, result from a shape fluctuation around the scission point caused by the random force in the Langevin equation. We found that a random vibration in the oblate direction of fissioning fragments is essential for the fission process. According to this picture, fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup. This is expected to lead to a new viewpoint of fission dynamics and the splitting mechanism.

Y. Aritomo; S. Chiba

2013-10-11T23:59:59.000Z

156

Analysis of fusion-fission dynamics by pre-scission neutron emission in $^{58}$Ni+$^{208}$Pb  

E-Print Network (OSTI)

We analyzed the experimental data of the pre-scission neutron multiplicity in connection with fission fragments in the reaction $^{58}$Ni+$^{208}$Pb at the incident energy corresponding to the excitation energy of compound nucleus $E^{*}$=185.9 MeV, which was performed by D\\'{e}MoN group. The relation between the pre-scission neutron multiplicity and each reaction process having different reaction time is investigated. In order to study the fusion-fission process accompanied by neutron emission, the fluctuation-dissipation model combined with a statistical model is employed. It is found that the fusion-fission process and the quasi-fission process are clearly distinguished in correlation with the pre-scission neutron multiplicity.

Y. Aritomo; M. Ohta; T. Materna; F. Hanappe; O. Dorvaux; L. Stuttge

2005-02-07T23:59:59.000Z

157

Pair breaking and Coulomb effects in cold fission from thermal neutron induced fission of U 233, U 235 and Pu 239  

E-Print Network (OSTI)

In this paper, the distribution of mass and kinetic energy in the cold region of the thermal neutron induced fission of U 233, U 235 and Pu 239, respectively, is interpreted in terms of nucleon pair-breaking and the Coulomb interaction energy between complementary fragments (Coulomb effect). In order to avoid the erosive consequences of neutron emission, one studies the cold fission regions, corresponding to total kinetic energy (TE) close to the maximum available energy of the reaction (Q). Contrary to expected, in cold fission is not observed high odd-even effect in mass number distribution. Nevertheless, the measured values are compatible with higher odd-even effects on proton or neutron number distribution, respectively. In addition, in cold fission, the minimal total excitation energy (X) is correlated with the Coulomb energy excess, which is defined as the difference between C (the electrostatic interaction energy between complementary fragments taken as spherical in scission configuration) and Q. These Coulomb effects increase with the asymmetry of the charge fragmentations. In sum, the experimental data on cold fission suggest that scission configurations explore all the possibilities permitted by the available energy for fission.

Modesto Montoya

2013-04-30T23:59:59.000Z

158

FISSION TARGET DESIGN AND INTEGRATION OF NEUTRON CONVERTER FOR EURISOL-DS PROJECT  

E-Print Network (OSTI)

A study of a new fission target for EURISOL-DS is presented with a detailed description of the target. Calculations of several configurations were done using Monte Carlo code FLUKA aimed to obtaining 1015 fissions/s on single target. In Eurisol, neutrons inducing the fission reactions are produced by a proton beam 1GeV-4mA interacting with a mercury converter. The target configuration was customized to gain fission yield from the large amount of low energy neutrons produced by the Hg converter. To this purpose, the fissile material is composed by discs of 238-Uranium carbide enriched with 15 g of 235-U. Studies of several geometries were done in order to define the shape and composition of uranium target, taking into account the mechanical and space constraints

J. Bermudez, O. Alyakrinskiy, M. Barbui, F. Negoita, L. Serbina, L.B. Tecchio, E. Udup

159

MCNP6 Fission Cross Section Calculations at Intermediate and High Energies  

E-Print Network (OSTI)

MCNP6 has been Validated and Verified (V&V) against intermediate- and high-energy fission cross-section experimental data. An error in the calculation of fission cross sections of 181Ta and a few nearby target nuclei by the CEM03.03 event generator in MCNP6 and a "bug: in the calculation of fission cross sections with the GENXS option of MCNP6 while using the LAQGSM03.03 event generator were detected during our V&V work. After fixing both problems, we find that MCNP6 using CEM03.03 and LAQGSM03.03 calculates fission cross sections in good agreement with available experimental data for reactions induced by nucleons, pions, and photons on both subactinide and actinide nuclei at incident energies from several tens of MeV to about 1 TeV.

Stepan G. Mashnik; Arnold J. Sierk; Richard E. Prael

2013-03-18T23:59:59.000Z

160

Nuclear-fission studies with relativistic secondary beams: analysis of fission channels  

E-Print Network (OSTI)

Nuclear fission of several neutron-deficient actinides and pre-actinides from excitation energies around 11 MeV was studied at GSI Darmstadt by use of relativistic secondary beams. The characteristics of multimodal fission of nuclei around 226Th are systematically investigated and interpreted as the superposition of three fission channels. Properties of these fission channels have been determined for 15 systems. A global view on the properties of fission channels including previous results is presented. The positions of the asymmetric fission channels are found to be constant in element number over the whole range of systems investigated.

C. Boeckstiegel; S. Steinhaeuser; K. -H. Schmidt; H. -G. Clerc; A. Grewe; A. Heinz; M. de Jong; A. R. Junghans; J. Mueller; B. Voss

2007-12-21T23:59:59.000Z

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.


161

Fission Properties for R-Process Nuclei  

Science Conference Proceedings (OSTI)

We present a systematics of fission barriers and fission lifetimes for the whole landscape of superheavy elements (SHE), i.e., nuclei with Z 100. The fission lifetimes are also compared with the -decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parametrizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bimodal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expected to be produced in the astrophysical r process.

Erler, J. [Inst. fur Theoretische Physik II, Univ. Erlangen-Numberg, Germany/UTK/ORNL; Langanke, K. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys./Frankfurt Inst. Advanced Studies, Germany; Loens, H. P. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys.; Martinez-Pinedo, G. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys.; Reinhard, P.-G. [Inst. fur Theoretische Physik II, Univ. Erlangen-Numberg, Germany

2012-01-01T23:59:59.000Z

162

Fission properties for r-process nuclei  

E-Print Network (OSTI)

We present a systematics of fission barriers and fission lifetimes for the whole landscape of super-heavy elements (SHE), i.e. nuclei with Z>100. The fission lifetimes are also compared with the alpha-decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parameterizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bi-modal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expected to be produced in the astrophysical r process.

J. Erler; K. Langanke; H. P. Loens; G. Martínez-Pinedo; P. -G. Reinhard

2011-12-05T23:59:59.000Z

163

Fission Product Yields of {sup 233}U, {sup 235}U, {sup 238}U and {sup 239}Pu in Fields of Thermal Neutrons, Fission Neutrons and 14.7-MeV Neutrons  

Science Conference Proceedings (OSTI)

The yields of more than fifteen fission products have been carefully measured using radiochemical techniques, for {sup 235}U(n,f), {sup 239}Pu(n,f) in a thermal spectrum, for {sup 233}U(n,f), {sup 235}U(n,f), and {sup 239}Pu(n,f) reactions in a fission neutron spectrum, and for {sup 233}U(n,f), {sup 235}U(n,f), {sup 238}U(n,f), and {sup 239}Pu(n,f) for 14.7 MeV monoenergetic neutrons. Irradiations were performed at the EL3 reactor, at the Caliban and Prospero critical assemblies, and at the Lancelot electrostatic accelerator in CEA-Valduc. Fissions were counted in thin deposits using fission ionization chambers. The number of fission products of each species were measured by gamma spectrometry of co-located thick deposits.

Laurec, J.; Adam, A.; Bruyne, T. de [Commissariat a l'Energie Atomique, Centre DAM-Ile de France (CEA DAM DIF), 91297 Arpajon (France); Bauge, E., E-mail: eric.bauge@cea.f [Commissariat a l'Energie Atomique, Centre DAM-Ile de France (CEA DAM DIF), 91297 Arpajon (France); Granier, T.; Aupiais, J.; Bersillon, O.; Le Petit, G. [Commissariat a l'Energie Atomique, Centre DAM-Ile de France (CEA DAM DIF), 91297 Arpajon (France); Authier, N.; Casoli, P. [Commissariat a l'Energie Atomique, Centre de Valduc, 21120 Is-sur-Tille (France)

2010-12-15T23:59:59.000Z

164

Characterization of a Stochastic Procedure for the Generation and Transport of Fission Fragments within Nuclear Fuels  

E-Print Network (OSTI)

With the ever-increasing demands of the nuclear power community to extend fuel cycles and overall core-lifetimes in a safe and economic manner, it is becoming more necessary to extend the working knowledge of nuclear fuel performance. From the atomistic to the macroscopic level, great morphological changes occur within the fuel over its lifetime. The main initial damaging events produced by fuel recoils from fast neutrons and fission fragment spiking leads to the onset of grain growths and fuel restructuring. Therefore, it is desirable to have a more detailed understanding of the initial events leading to fuel morphology changes at the atomistic level. However, this is difficult to achieve with the fission fragments due to the wide variability of their species (charge, mass, and energy) and the large averaging of their relative yields in the nuclear data files. This work is our first iteration at developing a general methodology to characterize a procedure, based on Monte Carlo principles, for generating individual fission event result channels and analyzing their specific response in the fuel. We utilized the nuclear reaction simulation tool, TALYS, to generate energy-dependent fission fragment yield distributions for different fissile/fissionable isotopes. These distributions can then be used in conjunction with fuel isotopics and a neutron energy spectrum to generate a fission-reaction-rate-averaged distribution of the fission fragment yields. We then used Monte Carlo sampling to generate the result channels from individual fission events, using the Q-value of the prompt fission system to either accept or reject. The simulation tool: Transport of Ions in Matter (TRIM) was used to characterize the general response of the fission fragment species within Uranium Dioxide (UO2), including the range, energy loss, displacements, recoils, etc. These responses were then correlated which allowed for the quick calculation of the response of the individual fission fragment species generated from the Monte Carlo sampling. As an example of this strategy, we calculated the response on a PWR fuel pin where MCNP was used to generate a high-fidelity neutron energy spectrum.

Hackemack, Michael Wayne

2013-05-01T23:59:59.000Z

165

Fission barriers and half-lives  

Science Conference Proceedings (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

166

RECOVERY OF ALUMINUM FROM FISSION PRODUCTS  

DOE Patents (OSTI)

A method is given for recovertng aluminum values from aqueous solutions containing said values together with fission products. A mixture of Fe/sub 2/O/ sub 3/ and MnO/sub 2/ is added to a solution containing aluminum and fission products. The resulting aluminum-containing supernatant is then separated from the fission product-bearing metal oxide precipitate and is contacted with a cation exchange resin. The aluminum sorbed on the resin is then eluted and recovered. (AEC)

Blanco, R.E.; Higgins, I.R.

1962-11-20T23:59:59.000Z

167

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

168

FISSION PRODUCT REMOVAL FROM ORGANIC SOLUTIONS  

DOE Patents (OSTI)

The decontamination of organic solvents from fission products and in particular the treatment of solvents that were used for the extraction of uranium and/or plutonium from aqueous acid solutions of neutron-irradiated uranium are treated. The process broadly comprises heating manganese carbonate in air to a temperature of between 300 and 500 deg C whereby manganese dioxide is formed; mixing the manganese dioxide with the fission product-containing organic solvent to be treated whereby the fission products are precipitated on the manganese dioxide; and separating the fission product-containing manganese dioxide from the solvent.

Moore, R.H.

1960-05-10T23:59:59.000Z

169

METHOD FOR SEPARATING PLUTONIUM AND FISSION PRODUCTS EMPLOYING AN OXIDE AS A CARRIER FOR FISSION PRODUCTS  

DOE Patents (OSTI)

Carrier precipitation processes for separating plutonium values from uranium fission products are described. Silicon dioxide or titanium dioxide in a finely divided state is added to an acidic aqueous solution containing hexavalent plutonium ions together with ions of uranium fission products. The supernatant solution containing plutonium ions is then separated from the oxide and the fission products associated therewith.

Davies, T.H.

1961-07-18T23:59:59.000Z

170

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

171

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

172

Isotopic yield measurement in the heavy mass region for {sup 239}Pu thermal neutron induced fission  

SciTech Connect

Despite the huge number of fission yield data available in the different evaluated nuclear data libraries, such as JEFF-3.1.1, ENDF/B-VII.0, and JENDL-4.0, more accurate data are still needed both for nuclear energy applications and for our understanding of the fission process itself. It is within the framework of this that measurements on the recoil mass spectrometer Lohengrin (at the Institut Laue-Langevin, Grenoble, France) was undertaken, to determine isotopic yields for the heavy fission products from the {sup 239}Pu(n{sub th},f) reaction. In order to do this, a new experimental method based on {gamma}-ray spectrometry was developed and validated by comparing our results with those performed in the light mass region with completely different setups. Hence, about 65 fission product yields were measured with an uncertainty that has been reduced on average by a factor of 2 compared to that previously available in the nuclear data libraries. In addition, for some fission products, a strongly deformed ionic charge distribution compared to a normal Gaussian shape was found, which was interpreted as being caused by the presence of a nanosecond isomeric state. Finally, a nuclear charge polarization has been observed in agreement, with the one described on other close fissioning systems.

Bail, A.; Serot, O.; Mathieu, L.; Litaize, O.; Materna, T.; Koester, U.; Faust, H.; Letourneau, A.; Panebianco, S. [CEA, DEN-Cadarache, F-13108 Saint-Paul-lez-Durance (France); Institut Laue Langevin, 6 rue Jules Horowitz, B.P. 156, F-38042, Grenoble (France); CEA, DSM-Saclay, IRFU/SPhN, F-91191 Gif-sur-Yvette (France)

2011-09-15T23:59:59.000Z

173

Some Considerations on the Probability of Nuclear Fission  

E-Print Network (OSTI)

om THE PROBABILITY OF NUCLEAR FISSION Robert Vandenbosch andON TRE PROBABILITY OF NUCLEAR FISSION O E Contents Abstractf is the fission threshold, and the nuclear temperature T is

Vandenbosch, Robert; Seaborg, Glenn T.

1957-01-01T23:59:59.000Z

174

THE WIDTH OF THE CHARGE DISTRIBUTION IN FISSION  

E-Print Network (OSTI)

the Charge Distribution in Fission William 0. Myers Nuclearnuclear collisions or in fission. Since the asymptotic widthin ref. [ 4] for the fission of ? 3fi U. As the neck between

Myers, W.D.

2010-01-01T23:59:59.000Z

175

ADIABATICITY CRITERION FOR CHARGE EQUILIBRATION WITH APPLICATION TO FISSION  

E-Print Network (OSTI)

with Application to Fission W. D. Myers, G. Mantzouranis andnuclear collisions and in fission. This work was supportedIn nuclear collisions and in fission the fluctuations in the

Myers, W.D.

2013-01-01T23:59:59.000Z

176

Monitoring system for a liquid-cooled nuclear fission reactor  

SciTech Connect

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

177

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

SciTech Connect

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

178

Nuclear Fission: Reaction to the Discovery in 1939  

E-Print Network (OSTI)

consequences of nuclear weapons in 1939, such informationdevelopment of both nuclear weapons and civilian reactorsresponsible for nuclear weapons—or to absolve them. Rather,

Hodes, Elizabeth; Tiddens, Adolph; Badash, Lawrence

1985-01-01T23:59:59.000Z

179

Fission decay of N = Z nuclei at high angular momentum: $^{60}$Zn  

E-Print Network (OSTI)

Using a unique two-arm detector system for heavy ions (the BRS, binary reaction spectrometer) coincident fission events have been measured from the decay of $^{60}$Zn compound nuclei formed at 88MeV excitation energy in the reactions with $^{36}$Ar beams on a $^{24}$Mg target at $E_{lab}(^{36}$Ar) = 195 MeV. The detectors consisted of two large area position sensitive (x,y) gas telescopes with Bragg-ionization chambers. From the binary coincidences in the two detectors inclusive and exclusive cross sections for fission channels with differing losses of charge were obtained. Narrow out-of-plane correlations corresponding to coplanar decay are observed for two fragments emitted in binary events, and in the data for ternary decay with missing charges from 4 up to 8. After subtraction of broad components these narrow correlations are interpreted as a ternary fission process at high angular momentum through an elongated shape. The lighter mass in the neck region consists dominantly of two or three-particles. Differential cross sections for the different mass splits for binary and ternary fission are presented. The relative yields of the binary and ternary events are explained using the statistical model based on the extended Hauser-Feshbach formalism for compound nucleus decay. The ternary fission process can be described by the decay of hyper-deformed states with angular momentum around 45-52 $hbar$.

W. Von Oertzen; V. Zherebchevsky; B. Gebauer; C. Schulz; S. Thummerer; D. Kamanin; G. Royer; T. Wilpert

2008-11-03T23:59:59.000Z

180

PROCESS FOR SEPARATING URANIUM FISSION PRODUCTS  

DOE Patents (OSTI)

The removal of fission products such as strontium, barium, cesium, rubidium, or iodine from neutronirradiated uranium is described. Uranium halide or elemental halogen is added to melted irradiated uranium to convert the fission products to either more volatile compositions which vaporize from the melt or to higher melting point compositions which separate as solids.

Spedding, F.H.; Butler, T.A.; Johns, I.B.

1959-03-10T23:59:59.000Z

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

SOURCE OF PRODUCTS OF NUCLEAR FISSION  

DOE Patents (OSTI)

A source of fission product recoil energy suitable for use in radiation chemistry is reported. The source consists of thermal neutron irradiated glass wool having a diameter of 1 to 5 microns and containing an isotope fissionable by thermal neutrons, such as U/sup 235/.

Harteck, P.; Dondes, S.

1960-03-15T23:59:59.000Z

182

Formation and Incorporation Energies of Fission Gases He, Xe, and ...  

Science Conference Proceedings (OSTI)

Presentation Title, Formation and Incorporation Energies of Fission Gases He, Xe , ... nuclear fuels are bcc alloys of uranium that swell under fission conditions, ...

183

Theoretical Description of the Fission Process  

Science Conference Proceedings (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

184

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

185

Los Alamos National Laboratory Fission Basis  

Science Conference Proceedings (OSTI)

This report is an overview of two main publications that provide a comprehensive review of the Los Alamos National Laboratory (LANL) Fission Basis. The first is the experimental paper, {sup F}ission Product Data Measured at Los Alamos for Fission Spectrum and Thermal Neutrons on {sup 239}Pu, {sup 235}U, {sup 238}U, [Selby, H. D., et al., Nucl. Data Sheets, Vol. 111 2010, pp. 2891-2922] and the second is the theoretical paper, Fission Product Yields from Fission Spectrum n+ {sup 239}Pu for ENDF/B-VII.1, [Chadwick, M. B., et al., Nucl. Data Sheets, Vol. 111, 2010, pp. 2923-2964]. One important note is that none of this work would have been possible without the great documentation of the experimental details and results by G.W. Knobeloch, G. Butler, C.I. Browne, B. Erdal, B. Bayhurst, R. Prestwood, V. Armijo, J. Hasty and many others. (authors)

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

2011-07-01T23:59:59.000Z

186

Systems analyses of fusion-driven fission  

SciTech Connect

Fusion-driven fissioning systems possess unique advantages not available in either pure fusion or pure fission systems. These systems can set a reasonably low maximum price for fissionable fuel, prevent the necessity of mining low-grade uranium ores, and possibly lead to the best way to exploit the vast fuel potential of our depleted uranium reserves. These systems are less demanding on the characteristics of the fusion systems making the advanced fusion fuels more accessible. By relieving the fission lattice of the need for criticality, more attractive fission system characteristics are allowed. Accurate economic predictions are not yet possible due to continuing uncertainty about the transport properties of reactor-grade plasmas. Hybrid systems have the potential to avoid the causes of most of the criticisms of nuclear power.

Mills, R.G.

1978-01-01T23:59:59.000Z

187

Fission-suppressed fusion breeder on the thorium cycle and nonproliferation  

SciTech Connect

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

188

Future challenges for nuclear data research in fission (u)  

Science Conference Proceedings (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

189

Non compound nucleus fission events and standard saddle-point statistical model  

E-Print Network (OSTI)

The large body of experimental data on the fission fragments anisotropies are analyzed in several heavy-ion induced fission reaction systems. The entrance channel mass asymmetry parameters of these systems put on the both sides of the Businaro-Gallone mass asymmetry parameters. The role of the mass numbers of the projectile and the target in the prediction of a normal or an anomalous behavior in angular anisotropy, as well as the validity of standard saddle-point statistical model are considered. The average contribution of non compound nucleus fission for the systems with an anomalous behavior in anisotropy are also determined. PACS numbers: 25.70.Jj *Corresponding author: s.soheyli@basu.ac.ir

S. Soheyli; M. K. Khalili

2013-09-11T23:59:59.000Z

190

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

191

Calculations of fission rates for r-process nucleosynthesis  

E-Print Network (OSTI)

Fission plays an important role in the r-process which is responsible not only for the yields of transuranium isotopes, but may have a strong influence on the formation of the majority of heavy nuclei due to fission recycling. We present calculations of beta-delayed and neutron-induced fission rates, taking into account different fission barriers predictions and mass formulae. It is shown that an increase of fission barriers results naturally in a reduction of fission rates, but that nevertheless fission leads to the termination of the r-process. Furthermore, it is discussed that the probability of triple fission could be high for $A>260$ and have an effect on the formation of the abundances of heavy nuclei. Fission after beta-delayed neutron emission is discussed as well as different aspects of the influence of fission upon r-process calculations.

I. V. Panov; E. Kolbe; B. Pfeiffer; T. Rauscher; K. -L. Kratz; F. -K. Thielemann

2004-12-29T23:59:59.000Z

192

Porous fission fragment tracks in fluorapatite  

Science Conference Proceedings (OSTI)

Fission tracks caused by the spontaneous fission of {sup 238}U in minerals, as revealed by chemical etching, are extensively used to determine the age and thermal history of Earth's crust. Details of the structure and annealing of tracks at the atomic scale have remained elusive, as the original track is destroyed during chemical etching. By combining transmission electron microscopy with in situ heating, we demonstrate that fission tracks in fluorapatite are actually porous tubes, instead of having an amorphous core, as generally assumed. Direct observation shows thermally induced track fragmentation in fluoapatite, in clear contrast to the amorphous tracks in zircon, which gradually ''fade'' without fragmentation. Rayleigh instability and the thermal emission of vacancies control the annealing of porous fission tracks in fluorapatite.

Li Weixing; Ewing, Rodney C. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States); Wang Lumin [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Sun Kai [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Lang, Maik [Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States); Trautmann, Christina [GSI Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt (Germany)

2010-10-01T23:59:59.000Z

193

Microscopic description of complex nuclear decay: multimodal fission  

E-Print Network (OSTI)

Our understanding of nuclear fission, a fundamental nuclear decay, is still incomplete due to the complexity of the process. In this paper, we describe a study of spontaneous fission using the symmetry-unrestricted nuclear density functional theory. Our results show that the observed bimodal fission can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. We also predict a new phenomenon of trimodal spontaneous fission for some rutherfordium, seaborgium, and hassium isotopes.

A. Staszczak; A. Baran; J. Dobaczewski; W. Nazarewicz

2009-06-23T23:59:59.000Z

194

Bimodal fission in the Skyrme-Hartree-Fock approach ?  

E-Print Network (OSTI)

studied within the Skyrme-Hartree-Fock+BCS framework. In the particlehole channel we take the Skyrme SkM ? effective force, while in the particleparticle channel we employ the seniority pairing interaction. Three static fission paths for all investigated heavy fermium isotopes are found. The analysis of these fission modes allows to describe observed asymmetric fission of 256 Fm, as well as bimodal fission of 258 Fm and symmetric fission in

A. Staszczak A; J. Dobaczewski B; W. Nazarewicz B

2006-01-01T23:59:59.000Z

195

The contrasting fission potential-energy structure of actinides and mercury isotopes  

E-Print Network (OSTI)

Fission-fragment mass distributions are asymmetric in fission of typical actinide nuclei for nucleon number $A$ in the range $228 \\lnsim A \\lnsim 258$ and proton number $Z$ in the range $90\\lnsim Z \\lnsim 100$. For somewhat lighter systems it has been observed that fission mass distributions are usually symmetric. However, a recent experiment showed that fission of $^{180}$Hg following electron capture on $^{180}$Tl is asymmetric. We calculate potential-energy surfaces for a typical actinide nucleus and for 12 even isotopes in the range $^{178}$Hg--$^{200}$Hg, to investigate the similarities and differences of actinide compared to mercury potential surfaces and to what extent fission-fragment properties, in particular shell structure, relate to the structure of the static potential-energy surfaces. Potential-energy surfaces are calculated in the macroscopic-microscopic approach as functions of fiveshape coordinates for more than five million shapes. The structure of the surfaces are investigated by use of an immersion technique. We determine properties of minima, saddle points, valleys, and ridges between valleys in the 5D shape-coordinate space. Along the mercury isotope chain the barrier heights and the ridge heights and persistence with elongation vary significantly and show no obvious connection to possible fragment shell structure, in contrast to the actinide region, where there is a deep asymmetric valley extending from the saddle point to scission. The mechanism of asymmetric fission must be very different in the lighter proton-rich mercury isotopes compared to the actinide region and is apparently unrelated to fragment shell structure. Isotopes lighter than $^{192}$Hg have the saddle point blocked from a deep symmetric valley by a significant ridge. The ridge vanishes for the heavier Hg isotopes, for which we would expect a qualitatively different asymmetry of the fragments.

Takatoshi Ichikawa; Akira Iwamoto; Peter Möller; Arnold J. Sierk

2012-03-09T23:59:59.000Z

196

MCNP6 Fission Multiplicity with FMULT Card  

Science Conference Proceedings (OSTI)

With the merger of MCNPX and MCNP5 into MCNP6, MCNP6 now provides all the capabilities of both codes allowing the user to access all the fission multiplicity data sets. Detailed in this paper is: (1) the new FMULT card capabilities for accessing these different data sets; (2) benchmark calculations, as compared to experiment, detailing the results of selecting these separate data sets for thermal neutron induced fission on U-235.

Wilcox, Trevor [Los Alamos National Laboratory; Fensin, Michael Lorne [Los Alamos National Laboratory; Hendricks, John S. [Los Alamos National Laboratory; James, Michael R. [Los Alamos National Laboratory; McKinney, Gregg W. [Los Alamos National Laboratory

2012-06-18T23:59:59.000Z

197

Overview of tritium fast-fission yields  

SciTech Connect

Tritium production rates are very important to the development of fast reactors because tritium may be produced at a greater rate in fast reactors than in light water reactors. This report focuses on tritium production and does not evaluate the transport and eventual release of the tritium in a fast reactor system. However, if an order-of-magnitude increase in fast fission yields for tritium is confirmed, fission will become the dominant production source of tritium in fast reactors.

Tanner, J.E.

1981-03-01T23:59:59.000Z

198

Modeling Fission Product Sorption in Graphite Structures  

SciTech Connect

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

199

Transport properties of fission product vapors  

DOE Green Energy (OSTI)

Kinetic theory of gases is used to calculate the transport properties of fission product vapors in a steam and hydrogen environment. Provided in tabular form is diffusivity of steam and hydrogen, viscosity and thermal conductivity of the gaseous mixture, and diffusivity of cesium iodide, cesium hydroxide, diatomic tellurium and tellurium dioxide. These transport properties are required in determining the thermal-hydraulics of and fission product transport in light water reactors.

Im, K.H.; Ahluwalia, R.K.

1983-07-01T23:59:59.000Z

200

Accurate fission data for nuclear safety  

E-Print Network (OSTI)

The Accurate fission data for nuclear safety (AlFONS) project aims at high precision measurements of fission yields, using the renewed IGISOL mass separator facility in combination with a new high current light ion cyclotron at the University of Jyvaskyla. The 30 MeV proton beam will be used to create fast and thermal neutron spectra for the study of neutron induced fission yields. Thanks to a series of mass separating elements, culminating with the JYFLTRAP Penning trap, it is possible to achieve a mass resolving power in the order of a few hundred thousands. In this paper we present the experimental setup and the design of a neutron converter target for IGISOL. The goal is to have a flexible design. For studies of exotic nuclei far from stability a high neutron flux (10^12 neutrons/s) at energies 1 - 30 MeV is desired while for reactor applications neutron spectra that resembles those of thermal and fast nuclear reactors are preferred. It is also desirable to be able to produce (semi-)monoenergetic neutrons for benchmarking and to study the energy dependence of fission yields. The scientific program is extensive and is planed to start in 2013 with a measurement of isomeric yield ratios of proton induced fission in uranium. This will be followed by studies of independent yields of thermal and fast neutron induced fission of various actinides.

A. Solders; D. Gorelov; A. Jokinen; V. S. Kolhinen; M. Lantz; A. Mattera; H. Penttila; S. Pomp; V. Rakopoulos; S. Rinta-Antila

2013-03-12T23:59:59.000Z

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

Spontaneous fission of the heaviest elements  

Science Conference Proceedings (OSTI)

Although spontaneous fission was discovered in /sup 238/U in 1940, detailed studies of the process were first made possible in the 1960's with the availability of milligram quantities of /sup 252/Cf. The advent of solid-state detectors made it possible to perform measurements of coincident fission fragments from even very short-lived spontaneous fission activities or those available in only very small quantities. Until 1971 it was believed that the main features of the mass and kinetic-energy distributions were essentially the same as those for thermal neutron-induced fission and that all low-energy fission proceeded via asymmetric mass division with total kinetic energies which could be derived by linear extrapolation from those of lighter elements. In 1971, measurements of /sup 257/Fm showed an increase in symmetric mass division with anomalously high TKE's. Subsequent experiments showed that in /sup 258/Fm and /sup 259/Fm, the most probable mass split was symmetric with very high total kinetic energy. Measurements for the heavier elements have shown symmetric mass distributions with both high and low total kinetic energies. Recent results for spontaneous fission properties of the heaviest elements are reviewed and compared with theory. 31 refs., 8 figs., 1 tab.

Hoffman, D.C.

1989-04-01T23:59:59.000Z

202

Anatomy of neck configuration in fission decay  

E-Print Network (OSTI)

The anatomy of neck configuration in the fission decay of Uranium and Thorium isotopes is investigated in a microscopic study using Relativistic mean field theory. The study includes $^{236}U$ and $^{232}Th$ in the valley of stability and exotic neutron rich isotopes $^{250}U$, $^{256}U$, $^{260}U$, $^{240}Th$, $^{250}Th$, $^{256}Th$ likely to play important role in the r-process nucleosynthesis in stellar evolution. Following the static fission path, the neck configurations are generated and their composition in terms of the number of neutrons and protons are obtained showing the progressive rise in the neutron component with the increase of mass number. Strong correlation between the neutron multiplicity in the fission decay and the number of neutrons in the neck is seen. The maximum neutron-proton ratio is about 5 for $^{260}$U and $^{256}$Th suggestive of the break down of liquid-drop picture and inhibition of the fission decay in still heavier isotopes. Neck as precursor of a new mode of fission decay like multi-fragmentation fission may also be inferred from this study.

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

2010-05-10T23:59:59.000Z

203

Spontaneous fission of /sup 259/Md  

SciTech Connect

The mass and kinetic energy distributions of fission fragments from the spontaneous fission of th newly discovered nuclide /sup 259/Md were obtained. /sup 259/Md was identified as the E. C. daughter of /sup 259/No, and was found to decay entirely (> 95%) by spontaneous fission with a 95-min half-life. From the kinetic energies measured for 397 pairs of coincident fragments, a mass distribution was derived that is symmetric with sigma = 13 amu. /sup 259/Md, together with /sup 258/Fm and /sup 259/Fm, form a select group of three nuclides whose mass division in spontaneous fission is highly symmetric. Unlike the total-kinetic-energy (TKE) distributions of /sup 258/Fm and /sup 259/Fm, which peak at approx. = to 240 MeV, this distribution for /sup 259/Md is broad and is 50 MeV lower in energy. Analysis of the mass and energy distributions shows that events near mass symmetry also exhibit a broad TKE distribution, with one-third of the symmetric events having TKEs less than 200 MeV. The associated of low TKEs with symmetric mass division in the fission of very heavy actinides is anomalous and inconsistent with theories based upon the emergence of fragment shells near the scission point. Either three-body fragmentation or peculiar fragment shapes are assumed as the cause for the large consumption of Coulomb energy observed for a significant fraction of symmetric fissions in /sup 259/Md. 6 figures.

Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Landrum, J.H.; Dougan, R.J.; Mustafa, M.; Ghiorso, A.; Nitschke, J.M.

1979-05-04T23:59:59.000Z

204

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 isotopes, with improvements on three aspects. One is more recent input data acquired from updated nuclear databases. the second one 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 last one is more carefully calculation of the average energy taken away by antineutrinos in thermal fission with the comparison of antineutrino spectrum from different models. The change in calculated antineutrino flux due to the new values of thermal fission energy is about 0.32%, and the uncertainties of the new values are about 50% smaller.

X. B. Ma; W. L. Zhong; L. Z. Wang; Y. X. Chen; J. Cao

2012-12-29T23:59:59.000Z

205

Ternary Fission of 249Cf(n,f) and 250Cf(SF)  

E-Print Network (OSTI)

+b. INTRODUCTION Nuclear fission is essentially a binaryternary fission data are of interest for nuclear physics innuclear reactors and also in used fuel elements due to spontaneous fission.

, S. Vermote

2013-01-01T23:59:59.000Z

206

CALCULATION OF MUON FINAL PROBABILITIES AFTER MUON-INDUCED FISSION IN FOUR-STATE BASIS  

E-Print Network (OSTI)

between heavy and light fission fragments is extended byenergies in actinides exceed the fission barrier height,so that prompt fission becomes possible,(l) The

Zhong-yu, Ma

2013-01-01T23:59:59.000Z

207

Melodic Fission in Trance Music: The Perception of Interleaved Vocal and Non-Vocal Melodies  

E-Print Network (OSTI)

W. J. 1968. Rhythmic fission and perceptual organization.  J. Dowling. “Rhythmic fission and perceptual organization,” 2 (2003): 217-249. Melodic Fission in Trance Music sources

Atherton, Lawrence John

2013-01-01T23:59:59.000Z

208

SPALLATION-FISSION COMPETITION IN ASTATINE COMPOUND NUCLEI FORMED BY HEAVY-ION BOMBARDMENT  

E-Print Network (OSTI)

Effect of Angular Momentum on Fission Probability (Thesis),R. Vandenbosch, Nuclear Fission, to be published in Nuclearfrom Heavy-lon-Induced Fission (Thesis), Lawrence Radiation

Thomas, T. Darrah; Gordon, Glen E.; Latimer, Robert M.; Seaborg, Glenn T.

2008-01-01T23:59:59.000Z

209

MICROSCOPIC CALCULATIONS OF FISSION BARRIERS AND CRITICAL ANGULAR MOMENTA FOR EXCITED HEAVY NUCLEAR SYSTEMS  

E-Print Network (OSTI)

Physics and Chemistry of Fission, Vienna 1969 (IAEA, ViennaDeformation energies along the fission path plotted againstMICROSCOPIC CALCULATIONS OF FISSION BARRIERS AND CRITICAL

Diebel, Michael

2013-01-01T23:59:59.000Z

210

ANGULAR MOMENTUM AND THE COLLECTIVE MODES EXCITED IN DEEP-INELASTIC PROCESSES AND IN FISSION  

E-Print Network (OSTI)

INELASTIC PROCESSES AND IN FISSION L. G. Moretto Lawrenceinelastic processes and fission have been studied in thealpha [10] and sequential fission probabilities and angular

Moretto, L.G.

2010-01-01T23:59:59.000Z

211

Ternary Fission of 249Cf(n,f) and 250Cf(SF)  

E-Print Network (OSTI)

al. , in Proc. Sem. on Fission, Corsendonk, Belgium, Worldand neutron induced fission of Cm and Cf isotopes”, Ph.D.emission probabilities (per fission) for the various ternary

, S. Vermote

2013-01-01T23:59:59.000Z

212

Microscopic Description of Nuclear Fission: Fission Barrier Heights of Even-Even Actinides  

E-Print Network (OSTI)

We evaluate the performance of modern nuclear energy density functionals for predicting inner and outer fission barrier heights and energies of fission isomers of even-even actinides. For isomer energies and outer barrier heights, we find that the self-consistent theory at the HFB level is capable of providing quantitative agreement with empirical data.

J. McDonnell; N. Schunck; W. Nazarewicz

2013-01-31T23:59:59.000Z

213

Microscopic Description of Nuclear Fission: Fission Barrier Heights of Even-Even Actinides  

E-Print Network (OSTI)

We evaluate the performance of modern nuclear energy density functionals for predicting inner and outer fission barrier heights and energies of fission isomers of even-even actinides. For isomer energies and outer barrier heights, we find that the self-consistent theory at the HFB level is capable of providing quantitative agreement with empirical data.

McDonnell, J; Nazarewicz, W

2013-01-01T23:59:59.000Z

214

THE THEORY OF NUCLEAR FISSION. IV. THE EFFECT OF THE MAGIC NUMBERS ON NUCLEAR FISSION  

SciTech Connect

German) The concepts of fission theory developed in previous works (Ann. Physik (7) 7, 333(1961)) are systematically developed. From the basic conception of shell structure dependent deformation of the fragments at the moment of their separation, magic effects result in the nuclear force potential between both fragments and the mean kinetic energy of the fragments whose interaction makes quantitatively comprehensible the observed fission asymmetry. The spontaneous fission of Cf/sup 252/ is discussed as an example. The symmetric fission of Bi/ sup 209/ (by deuterons) is described. A qualitative clarification is given of the known decrease in fission asymmetry with increased excitation energy on the basis of the general hypotheses developed. (tr-auth)

Brunner, W.; Paul, H.

1961-01-01T23:59:59.000Z

215

Spectroscopy of element 115 decay chains  

Science Conference Proceedings (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

216

Nuclear Reactions  

NLE Websites -- All DOE Office Websites (Extended Search)

Reactions Nuclear reactions and nuclear scattering are used to measure the properties of nuclei. Reactions that exchange energy or nucleons can be used to measure the energies of...

217

Bimodal fission in the Skyrme-Hartree-Fock approach  

E-Print Network (OSTI)

Spontaneous-fission properties of 256Fm, 258Fm, and 260Fm isotopes are studied within the Skyrme-Hartree-Fock+BCS framework. In the particle-hole channel we take the Skyrme SkM* effective force, while in the particle-particle channel we employ the seniority pairing interaction. Three static fission paths for all investigated heavy fermium isotopes are found. The analysis of these fission modes allows to describe observed asymmetric fission of 256Fm, as well as bimodal fission of 258Fm and symmetric fission in 260Fm.

A. Staszczak; J. Dobaczewski; W. Nazarewicz

2006-12-04T23:59:59.000Z

218

Laser amplifier chain  

DOE Patents (OSTI)

A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.

Hackel, Richard P. (Livermore, CA)

1992-01-01T23:59:59.000Z

219

Laser amplifier chain  

DOE Patents (OSTI)

A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain. 6 figs.

Hackel, R.P.

1992-10-20T23:59:59.000Z

220

Statistics at work in heavy-ion reactions  

Science Conference Proceedings (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

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221

Manhattan Project: Fission Comes to America, 1939  

Office of Scientific and Technical Information (OSTI)

Excerpt from the comic book "Adventures Inside the Atom." Click on this image or visit the "Library" to view the whole comic book. FISSION COMES TO AMERICA Excerpt from the comic book "Adventures Inside the Atom." Click on this image or visit the "Library" to view the whole comic book. FISSION COMES TO AMERICA (1939) Events > Atomic Discoveries, 1890s-1939 A Miniature Solar System, 1890s-1919 Exploring the Atom, 1919-1932 Atomic Bombardment, 1932-1938 The Discovery of Fission, 1938-1939 Fission Comes to America, 1939 News of the fission experiments of Otto Hahn and Fritz Strassmann, and of the Meitner-Frisch calculations that confirmed them, spread rapidly. Meitner and Frisch communicated their results to Niels Bohr, who was in Copenhagen preparing to depart for the United States via Sweden and England. Bohr confirmed the validity of the findings while sailing to New York City, arriving on January 16, 1939. Ten days later Bohr, accompanied by Enrico Fermi, communicated the latest developments to some European émigré scientists who had preceded him to this country and to members of the American scientific community at the opening session of a conference on theoretical physics in Washington, D.C.

222

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

Science Conference Proceedings (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

223

METHOD OF MAKING JACKETED FISSIONABLE SLUG  

DOE Patents (OSTI)

BS>A method is described for fabricating a jacketed fissionable body or slug to provide an effective leak-proof seal between the jacket and the end closure. A housing for the fissionable slug is first formed and then tinned on the interior. The fissionable slug is coated on its exterior surface with the same material used to tin the interior of the housing. The coated slug is then inserted into the housing. A disc shaped end closure for the housing, coated with the tinning material, is inserted into the open end of the housing while the tinning material is still liquid. The end of the housing is then swaged into good contact with the periphery of the closure.

Young, G.J.; Ohlinger, L.A.

1959-02-10T23:59:59.000Z

224

Low-mass fission detector for the fission neutron spectrum measurement  

Science Conference Proceedings (OSTI)

For the fission neutron spectrum measurement, the neutron energy is determined in a time-of-flight experiment by the time difference between the fission event and detection of the neutron. Therefore, the neutron energy resolution is directly determined by the time resolution of both neutron and fission detectors. For the fission detection, the detector needs not only a good timing response but also the tolerance of radiation damage and high {alpha}-decay rate. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to particles, which is important for experiments with - emitting actinides. Therefore, a PPAC is an ideal detector for experiments requiring a fast and clean trigger for fission. In the following sections, the description will be given for the design and performance of a new low-mass PPAC for the fission-neutron spectrum measurements at LANL.

Wu, C Y; Henderson, R; Gostic, J; Haight, R C; Lee, H Y

2010-10-20T23:59:59.000Z

225

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 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

226

Biofuel Supply Chain Infrastructure  

NLE Websites -- All DOE Office Websites (Extended Search)

Research Areas Freight Flows Passenger Flows Supply Chain Efficiency Transportation: Energy Environment Safety Security Vehicle Technologies The Infrastructure Challenge of...

227

Italian hybrid and fission reactors scenario analysis  

SciTech Connect

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

228

Fission-Suppressed Fusion, Thorium-Cycle Breeder and Nonproliferation  

Science Conference Proceedings (OSTI)

Fusion-Fission Hybrids and Transmutation / Proceedings of the Fifteenth International Conference on Emerging Nuclear Energy Systems

R. W. Moir

229

Optimally moderated nuclear fission reactor and fuel source therefor  

DOE Patents (OSTI)

An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated state.

Ougouag, Abderrafi M. (Idaho Falls, ID); Terry, William K. (Shelley, ID); Gougar, Hans D. (Idaho Falls, ID)

2008-07-22T23:59:59.000Z

230

Chemical States of Volatile and Corrosive Fission Products in ...  

Science Conference Proceedings (OSTI)

Page 1. Chemical States of Volatile and Corrosive Fission Products in Thorium Based Fuels from Thermodynamic Studies ...

2006-07-20T23:59:59.000Z

231

Modeling of Fission Neutrons as a Signature for Detection of Highly Enriched Uranium  

SciTech Connect

We present the results of modeling intended to evaluate the feasibility of using neutrons from induced fission in highly enriched uranium (HEU) as a means of detecting clandestine HEU, even when it is embedded in absorbing surroundings, such as commercial cargo. We characterized radiation from induced fission in HEU, which consisted of delayed neutrons at all energies and prompt neutrons at energies above a threshold. We found that for the candidate detector and for the conditions we considered, a distinctive HEU signature should be detectable, given sufficient detector size, and should be robust over a range of cargo content. In the modeled scenario, an intense neutron source was used to induce fissions in a spherical shell of HEU. To absorb, scatter, and moderate the neutrons, we place one layer of simulated cargo between the source and target and an identical layer between the target and detector. The resulting neutrons and gamma rays are resolved in both time and energy to reveal the portion arising from fission. We predicted the dominant reaction rates within calcium fluoride and liquid organic scintillators. Finally, we assessed the relative effectiveness of two common neutron source energies.

Wolford, J K; Frank, M I; Descalle, M

2004-03-09T23:59:59.000Z

232

Prompt muon-induced fission: a sensitive probe for nuclear energy dissipation and fission dynamics  

E-Print Network (OSTI)

Following the formation of an excited muonic atom, inner shell transitions may proceed without photon emission by inverse internal conversion, i.e. the muonic excitation energy is transferred to the nucleus. In actinides, the 2p -> 1s and the 3d -> 1s muonic transitions result in excitation of the nuclear giant dipole and giant quadrupole resonances, respectively, which act as doorway states for fission. The nuclear excitation energy is typically 6.5 - 10 MeV. Because the muon lifetime is long compared to the timescale of prompt nuclear fission, the motion of the muon in the Coulomb field of the fissioning nucleus may be utilized to learn about the dynamics of fission.

Volker E. Oberacker; A. Sait Umar; Feodor F. Karpeshin

2004-03-30T23:59:59.000Z

233

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

2012-12-13T23:59:59.000Z

234

Improving MPI communication via data type fission  

Science Conference Proceedings (OSTI)

Message Passing Interface (MPI) messages are centered around transmitting instances of MPI data types. The data types represented in MPI terms are usually modeled after data types native to the application. If a user does not want to transmit a field ... Keywords: MPI, communication, data type fission, static transformation

Ben Perry; Martin Swany

2010-06-01T23:59:59.000Z

235

A CHEMICAL METHOD OF TREATING FISSIONABLE MATERIAL  

DOE Patents (OSTI)

One step of a process for separating plutonium from uranium and fission products is presented. A nitric acid solution containing these constituents is treated with formic acid to reduce simultaneously the plutonium to a valence state of not greater than +4 and destroy and eliminate the excess nitric acid.

Olson, C.M.

1959-09-01T23:59:59.000Z

236

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 diversion of spent fuel for a nuclear weapons program. The power history experienced by a fuel assembly is distinct and could serve as the basis of a method for unique identification. Using fission product concentrations to characterize the assembly power history would limit the ability of a proliferator to deceive the identification method. As part of the work completed, the TransLat lattice physics code was successfully benchmarked for fuel depletion. By developing analytical models for potential monitor isotopes an understanding was built of how specific isotope characteristics affect the production and destruction mechanisms that determine fission product concentration. With this knowledge potential monitor isotopes were selected and tested for concentration differences as a result of power history variations. Signature ratios were found to have significant concentration differences as a result of power history variations while maintaining a constant final burnup. A conceptual method for implementation of a fission product identification system was proposed in conclusion.

Sweeney, David J.

2008-12-01T23:59:59.000Z

237

Prompt muon-induced fission: a sensitive probe for nuclear energy dissipation and fission dynamics  

E-Print Network (OSTI)

Following the formation of an excited muonic atom, inner shell transitions may proceed without photon emission by inverse internal conversion, i.e. the muonic excitation energy is transferred to the nucleus. In actinides, the 2p ? 1s and the 3d ? 1s muonic transitions result in excitation of the nuclear giant dipole and giant quadrupole resonances, respectively, which act as doorway states for fission. The nuclear excitation energy is typically 6.5 ? 10 MeV. Because the muon lifetime is long compared to the timescale of prompt nuclear fission, the motion of the muon in the Coulomb field of the fissioning nucleus may be utilized to learn about the dynamics of fission. If there is large friction between the outer fission barrier and the scission point the muon will remain in the lowest molecular energy level and emerge in the 1s bound state of the heavy fission fragment. On the other hand, if friction is small (i.e. the nuclear collective motion is fast) there is a nonvanishing probability that the muon may be promoted to higher-lying molecular orbitals, e.g. the 2p? level, from where

Volker E. Oberacker; A. Sait Umar; Feodor F. Karpeshin

2008-01-01T23:59:59.000Z

238

Induction of nuclear fission by high-voltage application  

E-Print Network (OSTI)

In nuclear power generation, fissile materials are mainly used. For example, $U^{235}$ is fissile and therefore quite essential for use of nuclear energy. However, the material $U^{235}$ has very small natural abundance less than 1 %. We should seek possibility of utilizing fissionable materials such as $U^{238}$ because natural abundance of such fissionable materials is generally much larger than fissile ones. In this paper, we show that thermal neutrons with vanishing kinetic energy can induce nuclear fission when high voltage is applied to fissionable materials. To obtain this result, we use the liquid-drop model for nuclei. Finally, we propose how fissionable materials can be utilized.

Hirokazu Maruyama

2007-11-20T23:59:59.000Z

239

Theory of nuclear fission: present status and prospects  

SciTech Connect

General properties of nuclear fission are reviewed and related to our present knowledge of fission theory. For this purpose the basic reasons for the shape of the fission barriers are discussed and their consequences compared with experimental results on barrier shapes and structures. Special emphasis is put on the asymmetry of the fission barriers and mass-distributions and its relation to the shells of the nascent fragment clusters. Finally the problem of a dynamical description of fission and its relation to the question of viscosity is discussed. (auth)

Mosel, U.; Goldberg, D.A.; Marion, J.B.; Wallace, S.J. (eds.)

1975-01-01T23:59:59.000Z

240

Fission Yield Measurements by Inductively Coupled Plasma Mass-Spectrometry  

SciTech Connect

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

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

ICT Supply Chain Risk Management  

Science Conference Proceedings (OSTI)

... ICT Supply Chain Risk Management Manager's Forum ... ICT Supply Chain Risk Management National Institute of Standards and Technology Page 6. ...

2013-06-04T23:59:59.000Z

242

Microfabricated electrochemiluminescence cell for chemical reaction detection  

DOE Patents (OSTI)

A detector cell for a silicon-based or non-silicon-based sleeve type chemical reaction chamber that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The detector cell is an electrochemiluminescence cell constructed of layers of silicon with a cover layer of glass, with spaced electrodes located intermediate various layers forming the cell. The cell includes a cavity formed therein and fluid inlets for directing reaction fluid therein. The reaction chamber and detector cell 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 ECL cell may also be used in synthesis instruments, particularly those for DNA amplification and synthesis.

Northrup, M. Allen (Berkeley, CA); Hsueh, Yun-Tai (Davis, CA); Smith, Rosemary L. (Davis, CA)

2003-01-01T23:59:59.000Z

243

Fifty years of nuclear fission: Nuclear data and measurements series  

Science Conference Proceedings (OSTI)

This report is the written version of a colloquium first presented at Argonne National Laboratory in January 1989. The paper begins with an historical preamble about the events leading to the discovery of nuclear fission. This leads naturally to an account of early results and understanding of the fission phenomena. Some of the key concepts in the development of fission theory are then discussed. The main theme of this discussion is the topography of the fission barrier, in which the interplay of the liquid-drop model and nucleon shell effects lead to a wide range of fascinating phenomena encompassing metastable isomers, intermediate-structure effects in fission cross-sections, and large changes in fission product properties. It is shown how study of these changing effects and theoretical calculations of the potential energy of the deformed nucleus have led to broad qualitative understanding of the nature of the fission process. 54 refs., 35 figs.

Lynn, J.E.

1989-06-01T23:59:59.000Z

244

HYPERFUSE: a hypervelocity inertial confinement system for fusion energy production and fission waste transmutation  

SciTech Connect

Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., /sup 137/Cs, /sup 90/Sr, /sup 129/I, /sup 99/Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,..cap alpha..), (n,..gamma..), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R=1.0 to 3.0) requirements.

Makowitz, H.; Powell, J.R.; Wiswall, R.

1980-01-01T23:59:59.000Z

245

Fragmentation of spherical radioactive heavy nuclei as a novel probe of transient effects in fission  

E-Print Network (OSTI)

Peripheral collisions with radioactive heavy-ion beams at relativistic energies are discussed as an innovative approach for probing the transient regime experienced by fissile systems evolving towards quasi-equilibrium. A dedicated experiment using the advanced technical installations of GSI, Darmstadt, permitted to realize ideal conditions for the investigation of relaxation effects in the meta-stable well. Combined with a highly sensitive experimental signature, it provides a measure of the transient effects with respect to the flux over the fission barrier. Within a two-step reaction process, 45 proton-rich unstable spherical isotopes produced by projectile-fragmentation of a stable 238U beam have been used as secondary projectiles. The fragmentation of the radioactive projectiles on lead results in nearly spherical compound nuclei which span a wide range in excitation energy and fissility. The decay of these excited systems by fission is studied with a dedicated set-up which permits the detection of both fission products in coincidence and the determination of their atomic numbers with high resolution. The width of the fission-fragment nuclear charge distribution is shown to be specifically sensitive to pre-saddle transient effects and is used to establish a clock for the passage of the saddle point. The comparison of the experimental results with model calculations points to a fission delay of (3.3+/-0.7).10-21s for initially spherical compound nuclei, independent of excitation energy and fissility. This value suggests a nuclear dissipation strength at small deformation of (4.5+/-0.5).1021s-1. The very specific combination of the physics and technical equipment exploited in this work sheds light on previous controversial conclusions.

C. Schmitt; K. -H. Schmidt; A. Keli?; A. Heinz; B. Jurado; P. N. Nadtochy

2010-04-07T23:59:59.000Z

246

Isotopic distribution of fission fragments in collisions between 238U beam and 9Be and 12C targets at 24 MeV/u  

E-Print Network (OSTI)

Inverse kinematics coupled to a high-resolution spectrometer is used to investigate the isotopic yields of fission fragments produced in reactions between a 238U beam at 24 MeV/u and 9Be and 12C targets. Mass, atomic number and isotopic distributions are reported for the two reactions. These informations give access to the neutron excess and the isotopic distribution widths, which together with the atomic-number and mass distributions are used to investigate the fusion-fission dynamics.

O. Delaune; F. Farget; O. B. Tarasov; A. M. Amthor; B. Bastin; D. Bazin; B. Blank; L. Cacéres; A. Chbihi; B. Fernandez-Dominguez; S. Grevy; O. Kamalou; S. Lukyanov; W. Mittig; D. J. Morrissey; J. Pereira; L. Perrot; M. -G. Saint-Laurent; H. Savajols; B. M. Sherrill; C. Stodel; J. C. Thomas; A. C. Villari

2013-02-08T23:59:59.000Z

247

Fusion-fission energy systems evaluation  

SciTech Connect

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

248

Phase Transition Induced Fission in Lipid Vesicles  

E-Print Network (OSTI)

In this work we demonstrate how the first order phase transition in giant unilamellar vesicles (GUVs) can function as a trigger for membrane fission. When driven through their gel-fluid phase transition GUVs exhibit budding or pearl formation. These buds remain connected to the mother vesicle presumably by a small neck. Cooling these vesicles from the fluid phase (T>Tm) through the phase transition into the gel state (Tfission of the neck, while the mother vesicle remains intact. Pearling tubes which formed upon heating break-up and decay into multiple individual vesicles which then diffuse freely. Finally we demonstrate that mimicking the intracellular bulk viscosity by increasing the bulk viscosity to 40cP does not affect the overall fission process, but leads to a significant decrease in size of the released vesicles.

C. Leirer; B. Wunderlich; V. M. Myles; M. F. Schneider

2010-05-24T23:59:59.000Z

249

Final excitation energy of fission fragments  

E-Print Network (OSTI)

We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition according to a level density description with a transition from a constant-temperature regime to a Fermi-gas regime. Complete or partial excitation-energy sorting is found at energies well above the transition energy.

Karl-Heinz Schmidt; Beatriz Jurado

2011-04-14T23:59:59.000Z

250

Fission of a multiphase membrane tube  

E-Print Network (OSTI)

A common mechanism for intracellular transport is the use of controlled deformations of the membrane to create spherical or tubular buds. While the basic physical properties of homogeneous membranes are relatively well-known, the effects of inhomogeneities within membranes are very much an active field of study. Membrane domains enriched in certain lipids in particular are attracting much attention, and in this Letter we investigate the effect of such domains on the shape and fate of membrane tubes. Recent experiments have demonstrated that forced lipid phase separation can trigger tube fission, and we demonstrate how this can be understood purely from the difference in elastic constants between the domains. Moreover, the proposed model predicts timescales for fission that agree well with experimental findings.

Jean-Marc Allain; Cornelis Storm; Aurelien Roux; Martine Ben Amar; Jean-Francois Joanny

2004-04-19T23:59:59.000Z

251

REMOVAL OF FISSION PRODUCTS FROM WATER  

DOE Patents (OSTI)

A process is given for precipitating fission products from a body of water having a pH of above 6.5. Calcium permanganate and ferrous sulfate are added in a molar ratio of l: 3, whereby a mixed precipitate of manganese dioxide, ferric hydroxide and calcium sulfate is formed; the precipitate carries the fisston products and settles to the bottom of the body of water. (AEC)

Rosinski, J.

1961-12-19T23:59:59.000Z

252

Delayed-fission properties of neutron-deficient americium nuclei  

Science Conference Proceedings (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

253

Undergraduate Measurements For Fission Reactor Applications  

Science Conference Proceedings (OSTI)

Undergraduate students at the University of Dallas (UD) have investigated elastic and inelastic neutron scattering cross sections on structural materials important for criticality considerations in nuclear fission processes. Neutrons scattered off of {sup 23}Na and {sup Nat}Fe were detected using neutron time-of-flight techniques at the University of Kentucky Low-Energy Nuclear Accelerator Facility. These measurements are part of an effort to increase the efficiency of power generation from existing fission reactors in the US and in the design of new fission systems. Students have learned the basics of how to operate the Model CN Van de Graaff generator at the laboratory, setup detectors and electronics, use data acquisition systems, and they are currently analyzing the angular dependence of the scattered neutrons for incident neutron energies of 3.57 and 3.80 MeV. Most students participating in the project will use the research experience as the material for their undergraduate research thesis required for all Bachelor of Science students at the University of Dallas. The first student projects on this topic were completed during the summer of 2010; an overview of student participation in this investigation and their preliminary results will be presented.

Hicks, S. F.; Kersting, L. J.; Lueck, C. J.; McDonough, P. [Department of Physics, University of Dallas, Irving TX 75019 (United States); Crider, B. P.; McEllistrem, M. T.; Peters, E. E. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Vanhoy, J. R. [Department of Physics, United States Naval Academy, Annapolis MD 21402 (United States)

2011-06-01T23:59:59.000Z

254

HYPERFUSE: a hypervelocity inertial confinement system for fusion energy production and fission waste transmutation  

Science Conference Proceedings (OSTI)

Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from a LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., /sup 137/Cs, /sup 90/Sr, /sup 129/I, /sup 99/Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,..cap alpha..), (n,..gamma..), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R = 1.0 to 3.0) requirements. These studies also indicate that masses on the order of 1.0 g at densities of rho greater than or equal to 500.0 g/cm/sup 3/ are required for a practical fusion-based fission product transmutation system.

Makowitz, H.; Powell, J.R.; Wiswall, R.

1980-01-01T23:59:59.000Z

255

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

Science Conference Proceedings (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

256

Silicon-based 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 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); Mariella, Jr., Raymond P. (Danville, CA); Carrano, Anthony V. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

1996-01-01T23:59:59.000Z

257

Silicon-based sleeve devices for chemical reactions  

DOE Patents (OSTI)

A silicon-based sleeve type chemical reaction chamber is described 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 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. 32 figs.

Northrup, M.A.; Mariella, R.P. Jr.; Carrano, A.V.; Balch, J.W.

1996-12-31T23:59:59.000Z

258

Measurement of the Fusion Probability, PCN, for Hot Fusion Reactions  

E-Print Network (OSTI)

Background: The cross section for forming a heavy evaporation residue in fusion reactions depends on the capture cross section, the fusion probability, PCN, i.e., the probability that the projectile-target system will evolve inside the fission saddle point to form a completely fused system rather than re-separating (quasifission), and the survival of the completely fused system against fission. PCN is the least known of these quantities. Purpose: To measure PCN for the reaction of 101.2 MeV 18O, 147.3 MeV 26Mg, 170.9 MeV 30Si and 195.3 MeV 36S with 197Au. Methods: We measured the fission fragment angular distributions for these reactions and used the formalism of Back to deduce the fusion-fission and quasifission cross sections. From these quantities we deduced PCN for each reaction. Results: The values of PCN for the reaction of 101.2 MeV 18O, 147.3 MeV 26Mg, 170.9 MeV 30Si and 195.3 MeV 36S with 197Au are 0.66, 1.00, 0.06, 0.13, respectively. Conclusions: The new measured values of PCN agree roughly with the semi-empirical system- atic dependence of PCN upon fissility for excited nuclei.

R. Yanez; W. Loveland; J. S. Barrett; L. Yao; B. B. Back; S. Zhu; T. L. Khoo

2013-06-17T23:59:59.000Z

259

Emergence of Fusion/Fission Cycling and Self-Organized Criticality from a Simulation Model of Early Complex Polities  

E-Print Network (OSTI)

H. 1999, Chiefdoms and the Fission-Fusion Process, AmericanEmergence of Fusion/Fission Cycling and Self-Organizedthe fusion and subsequent fission of dynamic political

Griffin, Arthur F

2011-01-01T23:59:59.000Z

260

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

E-Print Network (OSTI)

1.1.3.1 Fission Energy . . . . . . . . . 1.1.3.21.1.3.3 Fission-Fusion Hybrids . . . . 1.2 Scope and Purposei CONTENTS Fission Blanket . . . . . . . . . . . . . . . . .

Kramer, Kevin James

2010-01-01T23:59:59.000Z

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.


261

Response to 'A comment on "Signatures of fissile materials: High-energy gamma rays following fission," by Zeev B. Alfassi'  

E-Print Network (OSTI)

high-energy ? rays following fission" by Zeev B. Alfassi ,radionuclides that are not fission products, but which emittemporal variation of the fission product gamma rays should

2004-01-01T23:59:59.000Z

262

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

263

Neutron flux profile monitor for use in a fission reactor  

DOE Patents (OSTI)

A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occured. Neutron flux profiles of reactor cores can be more accurately measured as a result.

Kopp, Manfred K. (Oak Ridge, TN); Valentine, Kenneth H. (Lenoir City, TN)

1983-01-01T23:59:59.000Z

264

Fission studies with 140 MeV $\\bm?$-Particles  

E-Print Network (OSTI)

Binary fission induced by 140 MeV $\\alpha$-particles has been measured for $^{\\rm nat}$Ag, $^{139}$La, $^{165}$Ho and $^{197}$Au targets. The measured quantities are the total kinetic energies, fragment masses, and fission cross sections. The results are compared with other data and systematics. A minimum of the fission probability in the vicinity $Z^2/A=24$ is observed.

A. Buttkewitz; H. H. Duhm; F. Goldenbaum; H. Machner; W. Strauss

2009-07-23T23:59:59.000Z

265

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

Science Conference Proceedings (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

266

Segregation of Fission Products to Dislocations in Uranium Dioxide  

Science Conference Proceedings (OSTI)

Abstract Scope, Irradiation of nuclear fuel leads to the formation of extended ... very important to understand the interaction of fission products with dislocations.

267

Glass Ceramic Waste Form Development for Fission Products from ...  

Science Conference Proceedings (OSTI)

Symposium, Materials Issues in Nuclear Waste Management in the 21st Century. Presentation Title, Glass Ceramic Waste Form Development for Fission ...

268

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

Office of Scientific and Technical Information (OSTI)

Fission And Nuclear Technologies Estimation of gas leak rates through very small orifices and channels. From sealed PuOsub 2 containers under accident conditions Bomelburg,...

269

Novel Fission-Product Separation Based on Room Temperature ...  

macrocyclic extractants and transport in new ... Future Research Plans 1. Synthesis and Optimization of ILs Tailored for Solvent Extraction of Fission ...

270

Thermodynamic Modelling of Volatile Fission Products during SFR ...  

Science Conference Proceedings (OSTI)

The creation of fission products can modify the physical and chemical properties of the nuclear fuel behaviour during operating conditions. A thermodynamic ...

271

Theoretical Investigation on Interplay of Defect Clusters and Fission ...  

Science Conference Proceedings (OSTI)

A prominent effect of the self-defect clusters in bulk matrix on the thermodynamic behavior of fission gases is found, a thermodynamic competition between the ...

272

Multiscale Computer Simulation of Fission Gas Release in Oxide Fuels  

Science Conference Proceedings (OSTI)

Central to the retention and release of fission gases is the evolution of bubbles existing on grain boundaries and grain triple junctions. This presentation will ...

273

Sensitivity of measured fission yields on prompt-neutron corrections  

E-Print Network (OSTI)

The amount of emitted prompt neutrons from the fission fragments increases as a function of excitation energy. Yet it is not fully understood whether the increase in \

A. Al-Adili; F. -J. Hambsch; S. Pomp; S. Oberstedt

2013-04-08T23:59:59.000Z

274

SEPARATION OF PLUTONIUM FROM URANIUM AND FISSION PRODUCTS  

DOE Patents (OSTI)

A chromatographic adsorption process is presented for the separation of plutonium from other fission products formed by the irradiation of uranium. The plutonium and the lighter element fission products are adsorbed on a sulfonated phenol-formaldehyde resin bed from a nitric acid solution containing the dissolved uranium. Successive washes of sulfuric, phosphoric, and nitric acids remove the bulk of the fission products, then an eluate of dilute phosphoric and nitric acids removes the remaining plutonium and fission products. The plutonium is selectively removed by passing this solution through zirconium phosphate, from which the plutonium is dissolved with nitric acid. This process provides a convenient and efficient means for isolating plutonium.

Boyd, G.E.; Adamson, A.W.; Schubert, J.; Russell, E.R.

1958-10-01T23:59:59.000Z

275

Generalized Energy-Dependent Q Values for Fission  

SciTech Connect

We extend Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q value for major and minor actinides on the incident neutron energies in the range 0 {le} E{sub n} {le} 20 MeV. Our parameterization is based on the actinide evaluations recommended for the ENDF/B-VII.1 release. This paper describes the calculation of energydependent fission Q values based on the calculation of the prompt energy release in fission by Madland. This calculation was adopted for use in the LLNL ENDL database and then generalized to obtain the prompt fission energy release for all actinides. Here the calculation is further generalized to the total energy release in fission. There are several stages in a fission event, depending on the time scale. Neutrons and gammas may be emitted at any time during the fission event.While our discussion here is focussed on compound nucleus creation by an incident neutron, similar parameterizations could be obtained for incident gammas or spontaneous fission.

Vogt, R

2010-03-31T23:59:59.000Z

276

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

277

Battery-Recycling Chain  

Science Conference Proceedings (OSTI)

...The battery-recycling chain has changed dramatically over the past ten years. The changes have resulted from environmental regulation, changes in battery-processing technology, changes in battery distribution and sales techniques, changes in lead-smelting...

278

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

279

ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data  

SciTech Connect

The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. The principal advances in the new library are: (1) An increase in the breadth of neutron reaction cross section coverage, extending from 393 nuclides to 418 nuclides; (2) Covariance uncertainty data for 185 of the most important nuclides, as documented in companion papers in this edition; (3) R-matrix analyses of neutron reactions on light nuclei, including isotopes of He, Li, and Be; (4) Resonance parameter analyses at lower energies and statistical high energy reactions at higher energies for isotopes of F, Cl, K, Ti, V, Mn, Cr, Ni, Zr and W; (5) Modifications to thermal neutron reactions on fission products (isotopes of Mo, Tc, Rh, Ag, Cs, Nd, Sm, Eu) and neutron absorber materials (Cd, Gd); (6) Improved minor actinide evaluations for isotopes of U, Np, Pu, and Am (we are not making changes to the major actinides 235,238U and 239Pu at this point, except for delayed neutron data, and instead we intend to update them after a further period of research in experiment and theory), and our adoption of JENDL-4.0 evaluations for isotopes of Cm, Bk, Cf, Es, Fm, and some other minor actinides; (7) Fission energy release evaluations; (8) Fission product yield advances for fission-spectrum neutrons and 14 MeV neutrons incident on 239Pu; and (9) A new Decay Data sublibrary. Integral validation testing of the ENDF/B-VII.1 library is provided for a variety of quantities: For nuclear criticality, the VII.1 library maintains the generally-good performance seen for VII.0 for a wide range of MCNP simulations of criticality benchmarks, with improved performance coming from new structural material evaluations, especially for Ti, Mn, Cr, Zr and W. For Be we see some improvements although the fast assembly data appear to be mutually inconsistent. Actinide cross section updates are also assessed through comparisons of fission and capture reaction rate measurements in critical assemblies and fast reactors. We describe the cross section evaluations that have been updated for ENDF/B-VII.1 and the measured data and calculations that motivated the changes, and therefore this paper augments the ENDF/B-VII.0 publication [1].

G. Palmiotti

2011-12-01T23:59:59.000Z

280

Nuclear multifragmentation and fission: similarity and differences  

E-Print Network (OSTI)

Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid–fog phase transition deep inside the spinodal region. The experimental data for p(8.1GeV) + Au collisions are analyzed. It is concluded that the decay process of hot nuclei is characterized by two size parameters: transition state and freeze-out volumes. The similarity between dynamics of fragmentation and ordinary fission is discussed. The IMF emission time is related to the mean rupture time at the multi-scission point, which corresponds to the kinetic freeze-out configuration. 1

V. Karnaukhov; H. Oeschler; S. Avdeyev; V. Rodionov; V. Kirakosyan; A. Simonenko; P. Rukoyatkin; A. Budzanowski; W. Karcz; I. Skwirczynska; B. Czech; L. Chulkov; E. Kuzmin; E. Norbeck; A. Botvina

2006-01-01T23:59:59.000Z

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.


281

Nuclear multifragmentation and fission: similarity and differences  

E-Print Network (OSTI)

Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid--fog phase transition deep inside the spinodal region. The experimental data for p(8.1GeV) + Au collisions are analyzed. It is concluded that the decay process of hot nuclei is characterized by two size parameters: transition state and freeze-out volumes. The similarity between dynamics of fragmentation and ordinary fission is discussed. The IMF emission time is related to the mean rupture time at the multi-scission point, which corresponds to the kinetic freeze-out configuration.

V. Karnaukhov; H. Oeschler; S. Avdeyev; V. Rodionov; V. Kirakosyan; A. Simonenko; P. Rukoyatkin; A. Budzanowski; W. Karcz; I. Skwirczynska; B. Czech; L. Chulkov; E. Kuzmin; E. Norbeck; A. Botvina

2006-02-10T23:59:59.000Z

282

SEPARATION OF URANIUM, PLUTONIUM AND FISSION PRODUCTS  

DOE Patents (OSTI)

The separation of uranium and plutonium from neutronirradiated uranium is described. The neutron-irradiated uranium is dissolved in nitric acid to provide an aqueous solution 3N in nitric acid. The fission products of the solution are extruded by treating the solution with dibutyl carbitol substantially 1.8N in nitric acid. The organic solvent phase is separated and neutralized with ammonium hydroxide and the plutonium reduced with hydroxylamine base to the trivalent state. Treatment of the mixture with saturated ammonium nitrate extracts the reduced plutonium and leaves the uranium in the organic solvent.

Nicholls, C.M.; Wells, I.; Spence, R.

1959-10-13T23:59:59.000Z

283

Uranium mill monitoring for natural fission reactors  

SciTech Connect

Isotopic monitoring of the product stream from operating uranium mills is proposed for discovering other possible natural fission reactors; aspects of their occurrence and discovery are considered. Uranium mill operating characteristics are formulated in terms of the total uranium capacity, the uranium throughput, and the dilution half-time of the mill. The requirements for detection of milled reactor-zone uranium are expressed in terms of the dilution half-time and the sampling frequency. Detection of different amounts of reactor ore with varying degrees of /sup 235/U depletion is considered.

Apt, K.E.

1977-12-01T23:59:59.000Z

284

Ceramics in fission and fusion technology  

SciTech Connect

The role of ceramic components in fission and fusion reactors is described. Almost all of the functions normally performed by ceramics, except mechanical, are required of nuclear ceramics. The oxides of uranium and plutonium are of predominant importance in nuclear applications, but a number of other ceramics play peripheral roles. The unique service conditions under which nuclear ceramics must operate include intense radiation fields, high temperatures and large temperature gradients, and aggressive chemical environments. Examples of laboratory research designed to broaden understanding of the behavior of uranium dioxide in such conditions are given. The programs described include high temperature vaporization, diffusional processes, and interaction with hydrogen.

Olander, D.R.

1986-04-01T23:59:59.000Z

285

FISSION OF 238U INDUCED BY INELASTIC SCATTERING OF 120 MeV 4-PARTICLES  

E-Print Network (OSTI)

Physics and Chemistry of Fission, Rochester, 1973, Vol. 2,kinetic energy (a) and the fission coincidence spectrum (b)for second and third chance fission are indicated by arrows.

Back, B.B.

2013-01-01T23:59:59.000Z

286

Nuclear Reactions  

E-Print Network (OSTI)

Nuclear reactions generate energy in nuclear reactors, in stars, and are responsible for the existence of all elements heavier than hydrogen in the universe. Nuclear reactions denote reactions between nuclei, and between nuclei and other fundamental particles, such as electrons and photons. A short description of the conservation laws and the definition of basic physical quantities is presented, followed by a more detailed account of specific cases: (a) formation and decay of compound nuclei; (b)direct reactions; (c) photon and electron scattering; (d) heavy ion collisions; (e) formation of a quark-gluon plasma; (f) thermonuclear reactions; (g) and reactions with radioactive beams. Whenever necessary, basic equations are introduced to help understand general properties of these reactions. Published in Wiley Encyclopedia of Physics, ISBN-13: 978-3-527-40691-3 - Wiley-VCH, Berlin, 2009.

C. A. Bertulani

2009-08-22T23:59:59.000Z

287

Mass-energy distribution of fragments within Langevin dynamics of fission induced by heavy ions  

SciTech Connect

A stochastic approach based on four-dimensional Langevin fission dynamics is applied to calculating mass-energy distributions of fragments originating from the fission of excited compound nuclei. In the model under investigation, the coordinate K representing the projection of the total angular momentum onto the symmetry axis of the nucleus is taken into account in addition to three collective shape coordinates introduced on the basis of the {l_brace}c, h, {alpha}{r_brace} parametrization. The evolution of the orientation degree of freedom (K mode) is described by means of the Langevin equation in the overdamped regime. The tensor of friction is calculated under the assumption of the reducedmechanismof one-body dissipation in the wall-plus-window model. The calculations are performed for two values of the coefficient that takes into account the reduction of the contribution from the wall formula: k{sub s} 0.25 and k{sub s} = 1.0. Calculations with a modified wall-plus-window formula are also performed, and the quantity measuring the degree to which the single-particle motion of nucleons within the nuclear system being considered is chaotic is used for k{sub s} in this calculation. Fusion-fission reactions leading to the production of compound nuclei are considered for values of the parameter Z{sup 2}/A in the range between 21 and 44. So wide a range is chosen in order to perform a comparative analysis not only for heavy but also for light compound nuclei in the vicinity of the Businaro-Gallone point. For all of the reactions considered in the present study, the calculations performed within four-dimensional Langevin dynamics faithfully reproduce mass-energy and mass distributions obtained experimentally. The inclusion of the K mode in the Langevin equation leads to an increase in the variances of mass and energy distributions in relation to what one obtains from three-dimensional Langevin calculations. The results of the calculations where one associates k{sub s} with the measure of chaoticity in the single-particle motion of nucleons within the nuclear system under study are in good agreement for variances of mass distributions. The results of calculations for the correlations between the prescission neutron multiplicity and the fission-fragment mass, Left-Pointing-Angle-Bracket n{sub pre}(M) Right-Pointing-Angle-Bracket , and between, this multiplicity and the kinetic energy of fission fragments, Left-Pointing-Angle-Bracket n{sub pre}(E{sub k}) Right-Pointing-Angle-Bracket , are also presented.

Anischenko, Yu. A., E-mail: yuri.anischenko@gmail.com; Adeev, G. D. [Omsk State University (Russian Federation)

2012-08-15T23:59:59.000Z

288

REGENERATION OF FISSION-PRODUCT-CONTAINING MAGNESIUM-THORIUM ALLOYS  

DOE Patents (OSTI)

A process of regenerating a magnesium-thorium alloy contaminated with fission products, protactinium, and uranium is presented. A molten mixture of KCl--LiCl-MgCl/sub 2/ is added to the molten alloy whereby the alkali, alkaline parth, and rare earth fission products (including yttrium) and some of the thorium and uranium are chlorinated and

Chiotti, P.

1964-02-01T23:59:59.000Z

289

SEPARATION OF FISSION PRODUCTS FROM PLUTONIUM BY PRECIPITATION  

DOE Patents (OSTI)

Fission product separation from hexavalent plutonium by bismuth phosphate precipitation of the fission products is described. The precipitation, according to this invention, is improved by coprecipitating ceric and zirconium phosphates (0.05 to 2.5 grams/liter) with the bismuth phosphate.

Seaborg, G.T.; Thompson, S.G.; Davidson, N.R.

1959-09-01T23:59:59.000Z

290

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

291

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 combustion are those powered by nuclear fission. Comparison of Chemical and Nuclear Rockets. Most existent.g., hydrogen and oxygen). In a nuclear rocket, or more precisely, a nuclear thermal rocket, the propellant

Ross, Shane

292

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

SciTech Connect

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

293

Response to 'A comment on 'Signatures of fissile materials:High-energy gamma rays following fission,' by Zeev B. Alfassi'  

DOE Green Energy (OSTI)

Prof. Alfassi has pointed out that radionuclides that are not fission products, but which emit {gamma} rays with energies E{sub {gamma}} > 3 MeV, can be produced by neutron irradiation. He suggested that the decays of such activation products would interfere with the identification of fissionable materials. However, the combination of the energy spectrum and the temporal variation of the fission product gamma rays can be used to distinguish fissionable material from other nuclides. The activation of nuclides that could produce interferences will depend upon the specifics of the cargo and, possibly, the local surroundings. As discussed in our original publication, in addition to the steel that Prof. Alfassi referred to in his Comment, we studied the activation of wood, polyethylene, aluminum, and sandstone. Activation by thermal neutrons will always occur, and Prof. Alfassi correctly points out that nuclides such as {sup 49}Ca and {sup 37}S can be formed in this way. These nuclides are representative of most potential interferences. Both {sup 48}Ca and {sup 36}S have very low isotopic abundances (0.187% and 0.02%, respectively) and small thermal neutron capture cross sections (0.20 barns and 0.98 barns, respectively). In addition, their half lives are more than an order of magnitude longer than the gross average observed from the fission products, and more than two orders of magnitude longer than the lifetimes of the shorter-lived fission products that contribute significantly to the total intensity in the energy range of interest. These differences make it possible to distinguish between fission products and thermal neutron activation products. Prof. Alfassi also pointed out that interferences, of which {sup 16}N is likely to be the most important, can be produced by fast neutron reactions. (As described in our original publication, we did not use a 14 MeV generator in our work.) Fortunately, a judicious choice of the source neutron energy can limit the extent of these interferences quite significantly. For example, the laboratory threshold for the reaction {sup 16}O(n,p){sup 16}N is 10.2 MeV, while that for the reaction {sup 19}F(n,{alpha}){sup 16}N is 1.6 MeV. Thus a source neutron energy around 5 MeV would completely eliminate the {sup 16}O(n,p){sup 16}N reaction and limit the {sup 19}F(n,{alpha}){sup 16}N reaction to that portion of the cargo in which neutrons with energies greater than 1.6 MeV were present. However, even in the presence of {sup 16}N, the energy spectrum and temporal variation of the fission product gamma rays should be decisive in distinguishing fissionable material from these interferences.

Norman, Eric B.; Prussin, Stanley G.; Larimer, Ruth-Mary; Shugart, Howard; Browne, Edgardo; Smith, Alan R.; McDonald, Richard J.; Nitsche, Heino; Gupta, Puja; Frank, Michael I.; Gosnell, Thomas B.

2004-06-03T23:59:59.000Z

294

Chain inflation revisited  

E-Print Network (OSTI)

This paper represents an in-depth treatment of the chain inflation scenario. We fully determine the evolution of the universe in the model, the necessary conditions in order to have a successful inflationary period, and the matching with the observational results regarding the cosmological perturbations. We study in great detail, and in general, the dynamics of the background, as well as the mechanism of generation of the perturbations. We also find an explicit formula for the spectrum of adiabatic perturbations. Our results prove that chain inflation is a viable model for solving the horizon, entropy and flatness problem of standard cosmology and for generating the right amount of adiabatic cosmological perturbations. The results are radically different from those found in previous works on the subject. Finally, we argue that there is a natural way to embed chain inflation into flux compactified string theory. We discuss the details of the implementation and how to fit observations.

Diego Chialva; Ulf H. Danielsson

2008-04-17T23:59:59.000Z

295

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

296

Continuous chain bit development  

DOE Green Energy (OSTI)

The continuous chain drill is a diamond drill bit in which the cutting surface can be replaced while the bit is still in the hole. The first prototype of the chain drill system was fabricated and tested in 1977. Problems were encountered with the mechanism used to cycle the bit. A second prototype bit was designed to circumvent these problems. An accelerated development and test program has provided field test results on Prototype II in less than 2 years. Field testing at Nevada Test Site has proven the feasibility of the downhole changing mechanism. The development and testing of this prototype are described.

St. Clair, J.A.; Duimstra, F.A.; Varnado, S.G.

1979-01-01T23:59:59.000Z

297

A new fission-fragment detector to complement the CACTUS-SiRi setup at the Oslo Cyclotron Laboratory  

E-Print Network (OSTI)

An array of Parallel Plate Avalanche Counters (PPAC) for the detection of heavy ions has been developed. The new device, NIFF (Nuclear Instrument for Fission Fragments), consists of four individual detectors and covers $60\\%$ of 2$\\pi$. It was designed to be used in conjunction with the SiRi array of ${\\Delta}E-E$ silicon telescopes for light charged particles and fits into the CACTUS array of 28 large-volume NaI scintillation detectors at the Oslo Cyclotron Laboratory. The low-pressure gas-filled PPACs are sensitive for the detection of fission fragments, but are insensitive to scattered beam particles of light ions or light-ion ejectiles. The PPAC detectors of NIFF have good time resolution and can be used either to select or to veto fission events in in-beam experiments with light-ion beams and actinide targets. The powerful combination of SiRi, CACTUS, and NIFF provides new research opportunities for the study of nuclear structure and nuclear reactions in the actinide region. The new setup is particularly well suited to study the competition of fission and $\\gamma$ decay as a function of excitation energy.

Tamás Gábor Tornyi; Andreas Görgen; Magne Guttormsen; Ann-Cecilie Larsen; Sunniva Siem; Attila Krasznahorkay; Lóránt Csige

2013-12-02T23:59:59.000Z

298

Neutron-induced astrophysical reaction rates for translead nuclei  

E-Print Network (OSTI)

Neutron-induced reaction rates, including fission, are calculated in the temperature range 1.d8 rates have been calculated, utilizing - where possible - consistent nuclear data for neutron separation energies and fission barriers from Thomas-Fermi (TF), Extended Thomas-Fermi plus Strutinsky Integral (ETFSI), Finite-Range Droplet Model (FRDM) and Hartree-Fock-Bogolyubov (HFB) predictions. Tables of calculated values as well as analytic seven parameter fits in the standard REACLIB format are supplied. We also discuss the sensitivity of the rates to the input, aiming at a better understanding of the uncertainties introduced by the nuclear input.

I. V. Panov; I. Yu. Korneev; T. Rauscher; G. Martínez-Pinedo; A. Keli?-Heil; N. T. Zinner; F. -K. Thielemann

2009-11-11T23:59:59.000Z

299

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

300

Budding and Fission of a multiphase vesicle  

E-Print Network (OSTI)

We present a model of bi-phasic vesicle in the limit of large surface tension. In this regime, the vesicle is completely stretched and well described by two spherical caps with a fold which concentrates the membrane stress. The conservation laws and geometric constraints restrict the space of possible shapes to a pair of solutions labeled by a parameter $\\tau$ given by {\\it line tension/pressure}. For a given $\\tau$ value, the two solutions differ by the length of the interface between domains. For a critical value $\\tau\\_c$, the two vesicle shapes become identical and no solution exists above this critical value. This model sheds new light on two proposed mechanisms (osmotic shocks and molecule absorption) to explain the budding and the fission in recent experiments.

Jean-Marc Allain; Martine Ben Amar

2005-04-08T23:59:59.000Z

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

Structural Materials for Fission and Fusion Energy  

SciTech Connect

Structural materials represent the key for containment of nuclear fuel and fission products as well as reliable and thermodynamically efficient production of electrical energy from nuclear reactors. Similarly, high-performance structural materials will be critical for the future success of proposed fusion energy reactors, which will subject the structures to unprecedented fluxes of high-energy neutrons along with intense thermomechanical stresses. Advanced materials can enable improved reactor performance via increased safety margins and design flexibility, in particular by providing increased strength, thermal creep resistance and superior corrosion and neutron radiation damage resistance. In many cases, a key strategy for designing highperformance radiation-resistant materials is based on the introduction of a high, uniform density of nanoscale particles that simultaneously provide good high temperature strength and neutron radiation damage resistance.

Zinkle, Steven J [ORNL; Busby, Jeremy T [ORNL

2009-01-01T23:59:59.000Z

302

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 enhanced neutron emission in the postsaddle stage of nuclear fission.

Gargi Chaudhuri; Santanu Pal

2001-05-04T23:59:59.000Z

303

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

Science Conference Proceedings (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

304

Fission Parameters Measurements for Np, Pu, Am, and Cm Isotopes Inside a Salt Blanket Micromodel  

E-Print Network (OSTI)

The MAKET zero-power heavy water reactor has been used at ITEP to measure the fission characteristics of the Np, Pu, Am, and Cm isotopes in the 0.52NaF+0.48ZrF_4 melt-filled salt blanket micromodel. The 237Np(n,f), 238Pu(n,f), 239Pu(n,f), 240Pu(n,f), 241Pu(n,f), 242m^Am(n,f), 243Cm(n,f), 245Cm(n,f), 247Cm(n,f), 238U(n,f), 238U(n,g), 235U(n,f) fission reaction rates have been measured. The neutron spectrum in the isotope irradiation locations was monitored by measuring the rates of the (235U(n,f), 238U(n,g), 55Mn(n,g), 63Cu(n,g), 176Lu(n,g), 197Au(n,g), 115In(n,n'), 27Al(n,4He), and 64Zn(n,p)) reactions whose cross sections have been commonly accepted. The measured functionals are compared with the respective results of MCNP code simulation obtained using the ENDF/B6 and JENDL3.2 neutron databases.

Yu. E. Titarenko; O. V. Shvedov; V. N. Konev; M. M. Igumnov; V. F. Batyaev; E. I. Karpikhin; V. M. Zhivun; A. B. Koldobsky; R. D. Mulambetov; D. V. Fischenko; S. V. Kvasova; E. F. Fomushkin; V. V. Gavrilov; G. F. Novoselov; A. V. Lopatkin; V. G. Muratov; A. F. Lositskiy; B. L. Kurushin; S. G. Mashnik; H. Yasuda

2002-09-06T23:59:59.000Z

305

Cluster expression in fission and fusion in high-dimensional macroscopic-microscopic calculations  

SciTech Connect

We discuss the relation between the fission-fusion potential-energy surfaces of very heavy nuclei and the formation process of these nuclei in cold-fusion reactions. In the potential-energy surfaces, we find a pronounced valley structure, with one valley corresponding to the cold-fusion reaction, the other to fission. As the touching point is approached in the cold-fusion entrance channel, an instability towards dynamical deformation of the projectile occurs, which enhances the fusion cross section. These two 'cluster effects' enhance the production of superheavy nuclei in cold-fusion reactions, in addition to the effect of the low compound-system excitation energy in these reactions. Heavy-ion fusion reactions have been used extensively to synthesize heavy elements beyond actinide nuclei. In order to proceed further in this direction, we need to understand the formation process more precisely, not just the decay process. The dynamics of the formation process are considerably more complex than the dynamics necessary to interpret the spontaneous-fission decay of heavy elements. However, before implementing a full dynamical description it is useful to understand the basic properties of the potential-energy landscape encountered in the initial stages of the collision. The collision process and entrance-channel landscape can conveniently be separated into two parts, namely the early-stage separated system before touching and the late-stage composite system after touching. The transition between these two stages is particularly important, but not very well understood until now. To understand better the transition between the two stages we analyze here in detail the potential energy landscape or 'collision surface' of the system both outside and inside the touching configuration of the target and projectile. In Sec. 2, we discuss calculated five-dimensional potential-energy landscapes inside touching and identify major features. In Sec. 3, we present calculated 'collision surfaces' for still separated targets and projectiles. Implications for SHE formation are discussed. Section 4 is a short summary of the present analysis.

Iwamoto, A. (Akira); Ichikawa, T. (Takatoshi); Moller, P. (Peter); Sierk, A. J. (Arnold J.)

2004-01-01T23:59:59.000Z

306

Semiclassical Interpretation of the Mass Asymmetry in Nuclear Fission  

E-Print Network (OSTI)

We give a semiclassical interpretation of the mass asymmetry in the fission of heavy nuclei. Using only a few classical periodic orbits and a cavity model for the nuclear mean field, we reproduce the onset of left-right asymmetric shapes at the fission isomer minimum and the correct topology of the deformation energy surface in the region of the outer fission barrier. We point at the correspondence of the single-particle quantum states responsible for the asymmetry with the leading classical orbits, both lying in similar equatorial planes perpendicular to the symmetry axis of the system.

M. Brack; S. M. Reimann; M. Sieber

1997-05-15T23:59:59.000Z

307

Fission converter heat removal and safety under accident conditions  

Science Conference Proceedings (OSTI)

The design and safety of the heat removal system of the Massachusetts Institute of Technology (MIT) design for a fission converter-based epithermal beam is discussed in this paper. Plate-type reactor fuel elements, used in the MIT research reactor (MITR-II), are also used for the fission converter. This fission converter-based beam provides epithermal neutron fluxes at the patient position in excess of 10{sup 10} n/cm{sup 2}s with very low contamination of fast neutrons and gamma rays.

Sutharshan, B.; Todreas, N.E.; Harling, O.K. [Massachusetts Inst. of Technology, Cambridge, MA (United States)

1996-12-31T23:59:59.000Z

308

Sensitivity analysis of the fission gas behavior model in BISON.  

Science Conference Proceedings (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

309

Neutrinos, Fission Cycling, and the r-process  

E-Print Network (OSTI)

It has long been suggested that fission cycling may play an important role in the r-process. Fission cycling can only occur in a very neutron rich environment. In traditional calculations of the neutrino driven wind of the core-collapse supernova, the environment is not sufficiently neutron rich to produce the r-process elements. However, we show that with a reduction of the electron neutrino flux coming from the supernova, fission cycling does occur and furthermore it produces an abundance pattern which is consistent with observed r-process abundance pattern in halo stars. Such a reduction can be caused by active-sterile neutrino oscillations or other new physics.

J. Beun; G. C. McLaughlin; R. Surman; W. R. Hix

2006-07-10T23:59:59.000Z

310

Coherent bremsstrahlung and GDR width from 252Cf cold fission  

E-Print Network (OSTI)

The energy spectrum of the high energy gamma-rays in coincidence with the prompt gamma rays has been measured for the spontaneous fission of 252Cf. The nucleus-nucleus coherent bremsstrahlung of the accelerating fission fragments is observed and the result has been substantiated with a theoretical calculation based on the coulomb acceleration model. The width of the giant dipole resonance (GDR) decay from the excited fission fragments has been extracted for the first time and compared with the thermal shape fluctuation model (TSFM) in the liquid drop formalism. The extracted GDR width is significantly smaller than the predictions of TSFM.

Deepak Pandit; S. Mukhopadhyay; Srijit Bhattacharya; Surajit Pal; A. De; S. R. Banerjee

2009-12-23T23:59:59.000Z

311

Neutrinos, Fission Cycling, and the r-process  

E-Print Network (OSTI)

It has long been suggested that fission cycling may play an important role in the r-process. Fission cycling can only occur in a very neutron rich environment. In traditional calculations of the neutrino driven wind of the core-collapse supernova, the environment is not sufficiently neutron rich to produce the r-process elements. However, we show that with a reduction of the electron neutrino flux coming from the supernova, fission cycling does occur and furthermore it produces an abundance pattern which is consistent with observed r-process abundance pattern in halo stars. Such a reduction can be caused by active-sterile neutrino oscillations or other new physics.

J. Beun; G. C. Mclaughlin; R. Surman; W. R. Hix; J. Beun

2006-01-01T23:59:59.000Z

312

RIGHT-LEFT ASYMMETRY OF RADIATION FROM FISSION  

E-Print Network (OSTI)

The effect of the right-left asymmetry is considered in the predicted earlier electric dipole radiation from fission fragments arising due to the Strutinski— Denisov induced polarisation mechanism. The magnitude of the asymmetry parameter is on the level of 10 ?3. That is in agreement with the recent experimental data on the radiative ROT effect in 235 U fission induced by cold polarised neutrons. PACS: 24.80.+y, 24.75.+i, 24.70.+s Key words: Fission, asymmetry, radiation, ROT-effect

F. F. Karpeshin

2008-01-01T23:59:59.000Z

313

Fission product behavior in the Molten Salt Reactor Experiment  

SciTech Connect

Essentially all the fission product data for numerous and varied samples taken during operation of the Molten Salt Reactor Experiment or as part of the examination of specimens removed after particular phases of operation are reported, together with the appropriate inventory or other basis of comparison, and relevant reactor parameters and conditions. Fission product behavior fell into distinct chemical groups. Evidence for fission product behavior during operation over a period of 26 months with $sup 235$U fuel (more than 9000 effective full-power hours) was consistent with behavior during operation using $sup 233$U fuel over a period of about 15 months (more than 5100 effective full- power hours). (auth)

Compere, E.L.; Kirslis, S.S.; Bohlmann, E.G.; Blankenship, F.F.; Grimes, W.R.

1975-10-01T23:59:59.000Z

314

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

E-Print Network (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 detection of special nuclear materials.

Vogt, R

2011-01-01T23:59:59.000Z

315

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

E-Print Network (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 detection of special nuclear materials.

R. Vogt; J. Randrup

2011-09-17T23:59:59.000Z

316

Systems Modeling for the Laser Fusion-Fission Energy (LIFE) Power Plant  

Science Conference Proceedings (OSTI)

Laser Fusion-Fission Hybrid / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)

W. R. Meier et al.

317

Nd:Glass Laser Design for Laser ICF Fission Energy (LIFE)  

Science Conference Proceedings (OSTI)

Laser Fusion-Fission Hybrid / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)

John Caird et al.

318

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

319

Molten Salt Fuel Version of Laser Inertial Fusion Fission Energy (LIFE)  

Science Conference Proceedings (OSTI)

Laser Fusion-Fission Hybrid / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)

R. W. Moir; H. F. Shaw; A. Caro; Larry Kaufman; J. F. Latkowski; J. Powers; P. E. A. Turchi

320

Active-Interrogation Measurements of Induced-Fission Neutrons from Low-Enriched Uranium  

Science Conference Proceedings (OSTI)

Protection and control of nuclear fuels is paramount for nuclear security and safeguards; therefore, it is important to develop fast and robust controlling mechanisms to ensure the safety of nuclear fuels. Through both passive- and active-interrogation methods we can use fast-neutron detection to perform real-time measurements of fission neutrons for process monitoring. Active interrogation allows us to use different ranges of incident neutron energy to probe for different isotopes of uranium. With fast-neutron detectors, such as organic liquid scintillation detectors, we can detect the induced-fission neutrons and photons and work towards quantifying a sample’s mass and enrichment. Using MCNPX-PoliMi, a system was designed to measure induced-fission neutrons from U-235 and U-238. Measurements were then performed in the summer of 2010 at the Joint Research Centre in Ispra, Italy. Fissions were induced with an associated particle D-T generator and an isotopic Am-Li source. The fission neutrons, as well as neutrons from (n, 2n) and (n, 3n) reactions, were measured with five 5” by 5” EJ-309 organic liquid scintillators. The D-T neutron generator was available as part of a measurement campaign in place by Padova University. The measurement and data-acquisition systems were developed at the University of Michigan utilizing a CAEN V1720 digitizer and pulse-shape discrimination algorithms to differentiate neutron and photon detections. Low-enriched uranium samples of varying mass and enrichment were interrogated. Acquired time-of-flight curves and cross-correlation curves are currently analyzed to draw relationships between detected neutrons and sample mass and enrichment. In the full paper, the promise of active-interrogation measurements and fast-neutron detection will be assessed through the example of this proof-of-concept measurement campaign. Additionally, MCNPX-PoliMi simulation results will be compared to the measured data to validate the MCNPX-PoliMi code when used for active-interrogation simulations.

J. L. Dolan; M. J. Marcath; M. Flaska; S. A. Pozzi; D. L. Chichester; A. Tomanin; P. Peerani; G. Nebbia

2012-07-01T23:59:59.000Z

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.


321

Rapid micro?uidic thermal cycler for polymerase chain reaction ...  

a Mechanical Engineering Department, University of California, Riverside, CA 92521, USA b Lawrence Livermore National Laboratory, Center for Micro and Nanotechnology, USA

322

METHOD AND APPARATUS FOR CONDUCTING A NUCLEAR CHAIN REACTION  

DOE Patents (OSTI)

A nuclear reactor is designed incorporating a slurry of uranium- containing particles in heavy water and including means for circulating the slurry and for cooling the slurry. (AEC)

Wigner, E.P.; Ohlinger, L.A.; Young, G.J.; Weinberg, A.M.

1962-09-01T23:59:59.000Z

323

Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction...  

NLE Websites -- All DOE Office Websites (Extended Search)

Y-12 Earn 11 R&D 100 Awards Jul 2, 2013 US, International Partners Remove Last Remaining HEU from Vietnam, Set Nuclear Security Milestone View All > Timeline Curious about NNSA...

324

Operation chaining asynchronous pipelined circuits  

Science Conference Proceedings (OSTI)

We define operation chaining (op-chaining) as an optimization problem to determine the optimal pipeline depth for balancing performance against energy demands in pipelined asynchronous designs. Since there are no clock period requirements, asynchronous ...

Girish Venkataramani; Seth C. Goldstein

2007-11-01T23:59:59.000Z

325

Numerical Simulation of Fission Gas Bubble Coarsening in Nuclear ...  

Science Conference Proceedings (OSTI)

The gas from these bubbles is periodically re-dissolved back in the nuclear fuel by very high-energy fission fragments that pass either through or near the gas ...

326

Fission Cross Section Measurements of Actinides at LANSCE  

Science Conference Proceedings (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. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the 235U standard. Recent measurements include the 233, 238U, 239-242Pu, and 243Am neutron-induced fission cross sections. In this paper preliminary results for fission cross sections of 243Am and 233U will be presented.

F. Tovesson; A. B. Laptev; T. S. Hill

2011-08-01T23:59:59.000Z

327

Recent advances in modeling fission cross sections over intermediate structures  

SciTech Connect

More accurate fission cross section calculations in presence of underlying intermediate structure are strongly desired. This paper recalls the common approximations used below the fission threshold and quantifies their impact. In particular, an exact expanded R-matrix Monte Carlo calculation of the intermediate structure, deeply mixed with the fluctuations of the class-I and II decay amplitudes, is shown. This paper also insists on the microscopic structure of the level densities as a function of the nucleus deformation and show preliminary neutron induced fission cross section calculations for {sup 239}Pu and {sup 240}Pu using newly calculated combinatorial level densities. Comparisons with recent evaluated and measured fission cross sections are made.

Bouland, Olivier [Los Alamos National Laboratory; Lynn, J. Eric [Los Alamos National Laboratory; Talou, Patrick [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

328

Browse by Discipline -- E-print Network Subject Pathways: Fission...  

Office of Scientific and Technical Information (OSTI)

Fission and Nuclear Technologies A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z Go to Research Collections E-prints Provided...

329

110101BenefitsNuclearFission.ppt [Read-Only]  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Benefits of Nuclear Fission to Benefits of Nuclear Fission to the Civilian Space Program Gary Langford Fission Project Manager NASA MSFC NERAC Nov. 6, 2001 2 * Outer solar system exploration. * Planetary or lunar surface missions (robotic or human). * High-performance propulsion for human missions. * Advanced applications. Uses of Nuclear Fission in the Civilian Space Program Highly advanced propulsion, extremely high power surface applications. 3 2000 2010 2020 2030 2040 Phase 1 * 10-500 kW NEP * 10-500 kW spacecraft & surface powerplants Phase 3 * 10-1000 MW, 0.1-1 kg/kW NEP * >2000 s Isp gas/plasma-based NTR Phase 2 * 1-100 MW, 1-10 kg/kW NEP * 900-1000 s Isp solid- core NTR * Multi-MW space & surface powerplants Kuiper Belt Exploration Triton Lander Europa Ocean Science Station Pluto Orbiter Large Asteroids Io Volcanic Observer

330

Identification of Fissionable Materials Using the Tagged Neutron Technique  

Science Conference Proceedings (OSTI)

This summary describes experiments to detect and identify fissionable materials using the tagged neutron technique. The objective of this work is to enhance homeland security capability to find fissionable material that may be smuggled inside shipping boxes, containers, or vehicles. The technique distinguishes depleted uranium from lead, steel, and tungsten. Future work involves optimizing the technique to increase the count rate by many orders of magnitude and to build in the additional capability to image hidden fissionable materials. The tagged neutron approach is very different to other techniques based on neutron die-away or photo-fission. This work builds on the development of the Associated Particle Imaging (API) technique at the Special Technologies Laboratory (STL) [1]. Similar investigations have been performed by teams at the Oak Ridge National Laboratory (ORNL), the Khlopin Radium Institute in Russia, and by the EURITRACK collaboration in the European Union [2,3,4].

R.P. Keegan, J.P. Hurley, J.R. Tinsley, R. Trainham

2009-06-30T23:59:59.000Z

331

Parallel Fission Bank Algorithms in Monte Carlo Criticality Calculations  

E-Print Network (OSTI)

In this work we describe a new method for parallelizing the source iterations in a Monte Carlo criticality calculation. Instead of having one global fission bank that needs to be synchronized, as is traditionally done, our ...

Romano, Paul Kollath

332

Transcriptional regulatory network for sexual differentiation in fission yeast  

E-Print Network (OSTI)

Abstract Background Changes in gene expression are hallmarks of cellular differentiation. Sexual differentiation in fission yeast (Schizosaccharomyces pombe) provides a model system for gene expression programs accompanying and driving cellular...

Mata, Juan; Wilbrey, Anna; Bahler, Jurg

2007-10-10T23:59:59.000Z

333

Present Status of the Theory of Fission of hot Nuclei  

E-Print Network (OSTI)

Recent progress in the theory of fission of hot nuclei is reported. We discuss in particular the properties of the friction form factor as function of the deformation (and possibly of the temperature) which are necessary to reproduce data concerning fission of hot nuclei and its accompanying light particle and ?-ray emission. Recent theoretical work gives support to a phenomenological friction form factor (proposed some time ago 1)), which is weak for compact shapes and increases on the way to scission. Fission is one of the main decay channels after fusion of two heavy ions. The following discussion is restricted mainly to systems for which Bohr’s hypothesis is valid, which states that the formation and decay of the compound nucleus are independent processes, i. e. fission starts only after a completely equilibrated compound

Peter Fröbrich

2004-01-01T23:59:59.000Z

334

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

335

Partition of actinides and fission products between metal and molten salt phases: Theory, measurement, and application to IFR pyroprocess development  

Science Conference Proceedings (OSTI)

The chemical basis of Integral Fast Reactor fuel reprocessing (pyroprocessing) is partition of fuel, cladding, and fission product elements between molten LiCl-KCl and either a solid metal phase or a liquid cadmium phase. The partition reactions are described herein, and the thermodynamic basis for predicting distributions of actinides and fission products in the pyroprocess is discussed. The critical role of metal-phase activity coefficients, especially those of rare earth and the transuranic elements, is described. Measured separation factors, which are analogous to equilibrium constants but which involve concentrations rather than activities, are presented. The uses of thermodynamic calculations in process development are described, as are computer codes developed for calculating material flows and phase compositions in pyroprocessing.

Ackerman, J.P.; Johnson, T.R.

1993-10-01T23:59:59.000Z

336

METHOD OF TESTING THERMAL NEUTRON FISSIONABLE MATERIAL FOR PURITY  

DOE Patents (OSTI)

A process is given for determining the neutronic purity of fissionable material by the so-called shotgun test. The effect of a standard neutron absorber of known characteristics and amounts on a neutronic field also of known characteristics is measured and compared with the effect which the impurities derived from a known quantity of fissionable material has on the same neutronic field. The two readings are then made the basis of calculation from which the amount of impurities can be computed.

Fermi, E.; Anderson, H.L.

1961-01-24T23:59:59.000Z

337

Fission and Nuclear Liquid-Gas Phase Transition  

E-Print Network (OSTI)

The temperature dependence of the liquid-drop fission barrier is considered, the critical temperature for the liquid-gas phase transition in nuclear matter being a parameter. Experimental and calculated data on the fission probability are compared for highly excited $^{188}$Os. The calculations have been made in the framework of the statistical model. It is concluded that the critical temperature for the nuclear liquid--gas phase transition is higher than 16 MeV.

E. A. Cherepanov; V. A. Karnaukhov

2007-03-30T23:59:59.000Z

338

Right-Left Asymmetry of Radiation from Fission  

E-Print Network (OSTI)

The effect of the right-left asymmetry is considered in the predicted earlier electric dipole radiation from fission fragments arising due to the Strutinski-Denisov induced polarisation mechanism. The magnitude of the asymmetry parameter is on the level of 10^-3. That is in agreement with the recent experimental data on the radiative ROT effect in ^{235}U fission induced by cold polarised neutrons.

F. F. Karpeshin

2007-10-09T23:59:59.000Z

339

Calculation of fission observables through event-by-event simulation  

E-Print Network (OSTI)

The increased interest in more exclusive fission observables has demanded more detailed models. We present here a new computational model, FREYA, that aims to meet this need by producing large samples of complete fission events from which any observable of interest can then be extracted consistently, including arbitrary correlations. The various model assumptions are described and the potential utility of the model is illustrated by means of several novel correlation observables.

J. Randrup; R. Vogt

2009-06-06T23:59:59.000Z

340

Present Status of the Theory of Fission of hot Nuclei  

E-Print Network (OSTI)

Recent progress in the theory of fission of hot nuclei is reported. We discuss in particular the properties of the friction formfactor as function of the deformation (and possibly of the temperature) which are necessary to reproduce data concerning fission of hot nuclei and its accompanying light particle and $\\gamma$-ray emission. Recent theoretical work gives support to a phenomenological friction form factor (proposed some time ago), which is weak for compact shapes and increases on the way to scission.

P. Fröbrich

2004-01-21T23:59:59.000Z

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.


341

Evaluation and compilation of fission product yields 1993  

SciTech Connect

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

342

MASS YIELDS FROM FISSION BY NEUTRONS BETWEEN THERMAL AND 14.7 MEV  

SciTech Connect

Radiochemically determined mass-yield curves are given for the fission of U/sup 235/ and U/sup 238/ by l4.7-Mev neutrons. Symmetric and to a less extent, very asymmetric modes of fission are more probable at that energy than in thermal fission. Yields of four fission products from the fission of U/sup 235/ have been measured as a function of neutron energy in the range thermal to 14 Mev. The yields of eleven masses have been measured from the fission of Np/sup 237/ by degraded fission spectrum neutrons. The mass-yield curve is similar to that from the thermal fission of Pu/sup 239/ with a ratio of peak to valley yields of approximately 175. Relative yields of one peak fission product and four valley fission products have been determdned under the following conditions: fission of U/sup 235/ and Pu/sup 239/ with thermal neutrons; fission of U/sup 235/ Pu/sup 239/ and U/sup 238/ with fission spectrum neutrons; and fission of U//sup 235/ and Pu/sup 239/ with the intermediate neutron spectrum at the center of the Los Alamos Fast Reactor. Absolute yields of Moss have been determined from the fission of U/sup 235/,Pu/sup 239/ with thermal neutrons. (auth)

Ford, G.P.; Gilmore, J.S.; Ames, D.P.; Balagna, J.P.; Barnes, J.W.; Comstock, A.A.; Cowan, G.A.; Elkin, P.B.; Hoffman, D.C.; Knobeloch, G.W.; Lang, E.J.; Melnick, M.A.; Minkkinen, C.O.; Pollock, B.D.; Sattizshn, J.E.; Stanley, C.W.; Warren, B.

1956-02-01T23:59:59.000Z

343

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

Science Conference Proceedings (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

344

Method to calibrate fission chambers in Campbelling mode  

Science Conference Proceedings (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

345

Study of electron-capture delayed fission in Am-232  

Science Conference Proceedings (OSTI)

An automated x-ray-fission coincidence system was designed and constructed by LLNL and Lawrence Berkeley National Laboratory (LBNL) for use inside the Gammasphere high efficiency gamma-ray detector array at LBNL. The x-ray-fission coincidence apparatus detection station consists of two surface barrier detectors (for detection of fission fragments) and two high-purity Ge (HPGe) planar x-ray detectors (for measurement of x-rays and low-energy gamma rays). The detection station is placed inside Gammasphere at the 88-Inch Cyclotron at LBNL and used in conjunction with Gammasphere to measure the x-rays, low-energy gamma-rays and fission fragments resulting from the ECDF process. A series of collaborative experiment between LLNL, LBNL, and LANL utilizing various components of the x-ray-fission coincidence apparatus to measure x-rays and gamma-rays in the decay of a stationary {sup 252}Cf source were performed to test the various components of the x-ray-fission coincidence apparatus. The test experiments have been completed and the data is currently being analyzed by LBNL. Preliminary test results indicate that the system performed better than expected (e.g., the x-ray detectors performed better than expected with no evidence of microphonic noise that would reduce the photon energy resolution).

Kreek, S.A.; Hall, H.L.; Hoffman, D.C. [Lawrence Livermore National Lab., CA (United States); Strellis, D. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Gregorich, K.E. [Lawrence Berkeley National Lab., CA (United States). Nuclear Science Div.

1996-03-18T23:59:59.000Z

346

Systematic Study of Fission Barriers of Excited Superheavy Nuclei  

E-Print Network (OSTI)

A systematic study of fission-barrier dependence on excitation energy has been performed using the self-consistent finite-temperature Hartree-Fock+BCS (FT-HF+BCS) formalism with the SkM* Skyrme energy density functional. The calculations have been carried out for even-even superheavy nuclei with Z ranging between 110 and 124. For an accurate description of fission pathways, the effects of triaxial and reflection-asymmetric degrees of freedom have been fully incorporated. Our survey demonstrates that the dependence of isentropic fission barriers on excitation energy changes rapidly with particle number, pointing to the importance of shell effects even at large excitation energies characteristic of compound nuclei. The fastest decrease of fission barriers with excitation energy is predicted for deformed nuclei around N=164 and spherical nuclei around N=184 that are strongly stabilized by ground-state shell effects. For nuclei 240Pu and 256Fm, which exhibit asymmetric spontaneous fission, our calculations predict a transition to symmetric fission at high excitation energies due to the thermal quenching of static reflection asymmetric deformations.

J. A. Sheikh; W. Nazarewicz; J. C. Pei

2009-04-24T23:59:59.000Z

347

Supply Chain - Submissions | Data.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Submissions Sustainable Supply Chains Submissions Let's Talk About Sustainable Supply Chain You are here Data.gov Communities Sustainable Supply Chain Sustainable Supply...

348

Chemical Reactions in DSMC  

Science Conference Proceedings (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

349

Baby Skyrmion chains  

E-Print Network (OSTI)

Previous results on multi-charged Baby Skyrmion solutions have pointed to a modular structure, comprised of charge two rings and single charge one Skyrmions, which combine to form higher charged structures. In this paper we present numerical evidence which shows an alternative finite chain, multi-charged global energy minimum Baby Skymion solution. We then proceed from the infinite plane, to Baby Skyrmions on a cylinder and then a torus, to obtain the solutions of periodic Baby Skyrmions, of which periodic segments will correspond to sections of large charge Baby Skyrmions in the plane.

Foster, D J

2009-01-01T23:59:59.000Z

350

Baby Skyrmion chains  

E-Print Network (OSTI)

Previous results on multi-charged Baby Skyrmion solutions have pointed to a modular structure, comprised of charge two rings and single charge one Skyrmions, which combine to form higher charged structures. In this paper we present numerical evidence which shows an alternative finite chain, multi-charged global energy minimum Baby Skymion solution. We then proceed from the infinite plane, to Baby Skyrmions on a cylinder and then a torus, to obtain the solutions of periodic Baby Skyrmions, of which periodic segments will correspond to sections of large charge Baby Skyrmions in the plane.

D. J. Foster

2009-04-24T23:59:59.000Z

351

Fusion Probability in the Reactions {sup 58}Fe+{sup 244}Pu and {sup 64}Ni+{sup 238}U  

Science Conference Proceedings (OSTI)

Mass-energy distributions, as well as capture cross-section of fission-like fragments for the reactions {sup 64}Ni+{sup 238}U and {sup 58}Fe+{sup 244}Pu leading to the formation of superheavy compound system with Z = 120 and N 182 at energies near the Coulomb barrier have been measured. Fusion-fission cross sections were estimated from the analysis of mass and total kinetic energy distributions. It was found that the fusion probability is about one order of magnitude higher for the reaction {sup 58}Fe+{sup 244}Pu than that for the reaction with {sup 64}Ni-ions.

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

2010-04-30T23:59:59.000Z

352

TRISO Fuel Performance: Modeling, Integration into Mainstream Design Studies, and Application to a Thorium-fueled Fusion-Fission Hybrid Blanket  

E-Print Network (OSTI)

generation [1, 5, 6, 7]. Nuclear fission energy systems thatgeneration from nuclear fission plants may in fact need toof a Hybrid Fusion-Fission Nuclear Energy System. ” Thesis.

Powers, Jeffrey

2011-01-01T23:59:59.000Z

353

Response of fission yeast to toxic cations involves cooperative action of the stress-activated protein kinase Spc1/Sty1 and the Hal4 protein kinase  

E-Print Network (OSTI)

1993. Experiments with Fission Yeast. A laboratory coursetranscriptional responses of fission yeast to environmentalWhitehall. 2002. Role of fission yeast Tup1-like repressors

Wang, L Y; Shimada, K; Morishita, M; Shiozaki, Kazuhiro

2005-01-01T23:59:59.000Z

354

Effect of transients in nuclear fission on multiplicity of prescission neutrons  

E-Print Network (OSTI)

Transients in the fission of highly excited nuclei are studied in the framework of the Langevin equation. Time-dependent fission widths are calculated which show that after the initial transients, a steady flow towards the scission point is established not only for nuclei which have fission barriers but also for nuclei which have no fission barrier. It is shown from a comparison of the transient time and the fission life time that fission changes from a diffusive to a transient dominated process over a certain transition region as a function of the spin of the fissioning nucleus. Multiplicities of prescission neutrons are calculated in a statistical model with as well as without a single swoop description of fission and they are found to differ in the transition region. We however find that the difference is marginal and hence a single swoop picture of fission though not strictly valid in the transition region can still be used in the statistical model calculations.

Gargi Chaudhuri; Santanu Pal

2002-04-19T23:59:59.000Z

355

NNSA TRITIUM SUPPLY CHAIN  

SciTech Connect

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

356

Neutron source capability assessment for cumulative fission yields measurements  

Science Conference Proceedings (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

357

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

Science Conference Proceedings (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

358

Spontaneous Muon Emission during Fission, a New Nuclear Radioactivity  

E-Print Network (OSTI)

In this paper the essential theoretical predictions for the nuclear muonic radioactivity are presented by using a special fission-like model similar with that used in description of the pionic emission during fission. Hence, a fission-like model for the muonic radioactivity takes into account the essential degree of freedom of the system: muon-fissility, muon-fission barrier height, etc. Using this model it was shown that most of the SHE-nuclei lie in the region where the muonic fissility parameters attain their limiting value X=1. Hence, the SHE-region is characterized by the absence of a classical barrier toward spontaneous muon and pion emissions. Numerical estimations on the yields for the natural muonic radioactivities of the transuranium elements as well numerical values for barrier heights are given only for even-even parent nuclei. Some experimental results from LCP-identification emission spectrum are reviewed. Also, the experimental results obtained by Khryachkov et al, using new spectrometer for investigation of ternary nuclear fission, are presented. The OPERA-experiment proposed to perform search for muonic radioactivity from lead nuclei, in the low background conditions offered by the Gran Sasso underground Laboratory (LNGS), is discussed.

D. B. Ion; M. L. D. Ion; Reveica Ion-Mihai

2011-01-24T23:59:59.000Z

359

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

360

Pom1 DYRK regulates localization of the Rga4 GAP to ensure bipolar activation of Cdc42 in fission yeast  

E-Print Network (OSTI)

in polarized cell growth in fission yeast. J Cell Sci 115,genes nda2 and nda3 of the fission yeast Schizosaccharomycesalpha 2- tubulin genes as fission yeast polarity mutants.

Tatebe, Hisashi; Nakano, Kentaro; Maximo, Rachel; Shiozaki, Kazuhiro

2008-01-01T23:59:59.000Z

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.


361

The fission yeast stress MAPK cascade regulates the pmp3+ gene that encodes a highly conserved plasma membrane protein.  

E-Print Network (OSTI)

transcription factor in fission yeast. Genes Dev. Degols, G.stress-activated kinase in fission yeast. Genes Dev. 12,MAP kinase pathway in fission yeast. Genes Dev. 10, 2289-

Wang, Ling-yu; Shiozaki, Kazuhiro

2006-01-01T23:59:59.000Z

362

The fission yeast stress MAPK cascade regulates the pmp3(+) gene that encodes a highly conserved plasma membrane protein  

E-Print Network (OSTI)

transcription factor in fission yeast. Genes Dev. Degols, G.stress-activated kinase in fission yeast. Genes Dev. 12,MAP kinase pathway in fission yeast. Genes Dev. 10, 2289-

Wang, Ling-yu; Shiozaki, Kazuhiro

2006-01-01T23:59:59.000Z

363

Development of a Micromegas TPC for Low Energy Heavy Ions Measurement for Nuclear Fission and Astrophysics Applications  

SciTech Connect

Time Projection Chambers are widely used since many years for tracking and identification of charged particles in high energy physics. We present a new R and D project to investigate the feasibility of a Micromegas TPC for low energy heavy ions detection. Two physics cases are relevant for this project. The first is the study of the nuclear fission of actinides by measuring the fission fragments properties (mass, nuclear charge, kinetic energy) that will be performed at different installations and in particular at the NFS facility to be built in the framework of the SPIRAL2 project in GANIL. The second physics case is the study of heavy ion reactions, like ({alpha},{gamma}), ({alpha},p), ({alpha},n) and all the inverse reactions in the energy range between 1.5 and 3 AMeV using both stable and radioactive beams. These reactions have a key role in p process in nuclear astrophysics to explain the synthesis of heavy proton-rich nuclei. Within the project, a large effort is devoted to Monte-Carlo simulations and a detailed benchmark of different simulation codes on the energy loss and range in gas of heavy ions at low energy has been performed. A new approach for simulating the ion charge state evolution in GEANT4 is also presented. Finally, preliminary results of an experimental test campaign on prototype are discussed.

Panebianco, S.; Dore, D.; Giomataris, I.; Papaevangelou, Th.; Vernoud, L. [CEA, Centre de Saclay, Institut de Recherche sur les lois Fondamentales de l' Univers, 91191 Gif-sur-Yvette (France); Axiotis, M.; Fanourakis, G.; Geralis, Th.; Harissopoulos, S.; Lagoyannis, A. [Institute of Nuclear Physics, NCRS ' Demokritos' , 15310 Aghia Paraskevi, Athens (Greece)

2011-10-28T23:59:59.000Z

364

Toward Designed Singlet Fission: Electronic States and Photophysics of  

NLE Websites -- All DOE Office Websites (Extended Search)

Designed Singlet Fission: Electronic States and Photophysics of Designed Singlet Fission: Electronic States and Photophysics of 1,3-Diphenylisobenzofuran Andrew F. Schwerin, Justin C. Johnson, Millicent B. Smith, Paiboon Sreearunothai, Duska Popovic, Jiri Cerny, Zdenek Havlas, Irina Paci, Akin Akdag, Matthew K. MacLeod, Xudong Chen, Donald E. David, Mark A. Ratner, John R. Miller, Arthur J. Nozik and Josef Michl J. Phys. Chem. A 114, 1457-1473 (2010). [Find paper at ACS Publications] Abstract: Single crystal molecular structure and solution photophysical properties are reported for 1,3-diphenylisobenzofuran (1), of interest as a model compound in studies of singlet fission. For the ground state of 1 and of its radical cation (1+*) and anion (1-*), we report the UV-visible absorption spectra, and for neutral 1, also the magnetic

365

Estimates of fission yields in nuclear criticality excursions  

SciTech Connect

There is a need for computer simulation of hypothetical criticality excursions involving significant quantities of fissionable materials, especially in fissile aqueous system. The need arises due to the requirements for the emergency planning of facilities where the fissionable materials are handled, processed, or stored; and the regulatory requirements associated with facility operation or conversion. It is proposed here that a data base of fission yeilds for critical experiments and known accidents (both aqueous and solid) should be generated by using existing or new computer codes. The success in compiling this data base would provide useful source-terms for criticality excursions, realistic estimates of emergency-response boundary, as well as a replacement for the ``rule-of-thumb`` or ``bounding`` method. 10 refs.

Choi, J.S. [Lawrence Livermore National Lab., CA (United States); Thompson, J.W. [Atlantic Nuclear Services, Ottawa, ON (Canada); Reed, R. [Westinghouse Savannah River Co., Aiken, SC (United States)

1995-06-01T23:59:59.000Z

366

Sputtering yield of Pu bombarded by fission Fragments from Cf  

Science Conference Proceedings (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

367

Microscopic description of Cf-252 cold fission yields  

E-Print Network (OSTI)

We investigate the cold fission of 252Cf within the two center shell model to compute the potential energy surface. The fission yields are estimated by using the semiclassical penetration approach. It turns out that the inner cold valley of the total potential energy is strongly connected with Z=50 magic number. The agreement with experimental values is very much improved only by considering mass and charge asymmetry degrees of freedom. Thus, indeed cold fission of 252Cf is a Sn-like radioactivity, related the other two "magic radioactivities", namely alpha-decay and heavy-cluster decay, called also Pb-like radioactivity. This calculation provides the necessary theoretical confidence to estimate the penetration cross section in producing superheavy nuclei, by using the inverse fusion process.

Mirea, M; Sandulescu, A

2009-01-01T23:59:59.000Z

368

Microscopic description of Cf-252 cold fission yields  

E-Print Network (OSTI)

We investigate the cold fission of 252Cf within the two center shell model to compute the potential energy surface. The fission yields are estimated by using the semiclassical penetration approach. It turns out that the inner cold valley of the total potential energy is strongly connected with Z=50 magic number. The agreement with experimental values is very much improved only by considering mass and charge asymmetry degrees of freedom. Thus, indeed cold fission of 252Cf is a Sn-like radioactivity, related the other two "magic radioactivities", namely alpha-decay and heavy-cluster decay, called also Pb-like radioactivity. This calculation provides the necessary theoretical confidence to estimate the penetration cross section in producing superheavy nuclei, by using the inverse fusion process.

M. Mirea; D. S. Delion; A. Sandulescu

2009-07-20T23:59:59.000Z

369

Exploring the multi-humped fission barrier of 238U via sub-barrier photofission  

E-Print Network (OSTI)

The photofission cross-section of 238U was measured at sub-barrier energies as a function of the gamma-ray energy using, for the first time, a monochromatic, high-brilliance, Compton-backscattered gamma-ray beam. The experiment was performed at the High Intensity gamma-ray Source (HIgS) facility at beam energies between E=4.7 MeV and 6.0 MeV and with ~3% energy resolution. Indications of transmission resonances have been observed at gamma-ray beam energies of E=5.1 MeV and 5.6 MeV with moderate amplitudes. The triple-humped fission barrier parameters of 238U have been determined by fitting EMPIRE-3.1 nuclear reaction code calculations to the experimental photofission cross section.

L. Csige; D. M. Filipescu; T. Glodariu; J. Gulyás; M. M. Günther; D. Habs; H. J. Karwowski; A. Krasznahorkay; G. C. Rich; M. Sin; L. Stroe; O. Tesileanu; P. G. Thirolf

2013-02-14T23:59:59.000Z

370

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

SciTech Connect

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

371

ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data  

Science Conference Proceedings (OSTI)

The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. The principal advances in the new library are: (1) An increase in the breadth of neutron reaction cross section coverage, extending from 393 nuclides to 423 nuclides; (2) Covariance uncertainty data for 190 of the most important nuclides, as documented in companion papers in this edition; (3) R-matrix analyses of neutron reactions on light nuclei, including isotopes of He; Li, and Be; (4) Resonance parameter analyses at lower energies and statistical high energy reactions for isotopes of Cl; K; Ti, V, Mn, Cr, Ni, Zr and W; (5) Modifications to thermal neutron reactions on fission products (isotopes of Mo, Tc, Rh, Ag, Cs, Nd, Sm, Eu) and neutron absorber materials (Cd, Gd); (6) Improved minor actinide evaluations for isotopes of U, Np, Pu, and Am (we are not making changes to the major actinides (235,238)U and (239)Pu at this point, except for delayed neutron data and covariances, and instead we intend to update them after a further period of research in experiment and theory), and our adoption of JENDL-4.0 evaluations for isotopes of Cm, Bk, Cf, Es; Fm; and some other minor actinides; (7) Fission energy release evaluations; (8) Fission product yield advances for fission-spectrum neutrons and 14 MeV neutrons incident on (239)Pu; and (9) A new decay data sublibrary. Integral validation testing of the ENDF/B-VII.1 library is provided for a variety of quantities: For nuclear criticality, the VII.1 library maintains the generally-good performance seen for VII.0 for a wide range of MCNP simulations of criticality benchmarks, with improved performance coming from new structural material evaluations, especially for Ti, Mn, Cr, Zr and W. For Be we see some improvements although the fast assembly data appear to be mutually inconsistent. Actinide cross section updates are also assessed through comparisons of fission and capture reaction rate measurements in critical assemblies and fast reactors, and improvements are evident. Maxwellian-averaged capture cross sections at 30 keV are also provided for astrophysics applications. We describe the cross section evaluations that have been updated for ENDF/B-VII.1 and the measured data and calculations that motivated the changes, and therefore this paper augments the ENDF/B-VII.0 publication [H.

Chadwick, M. B. [Los Alamos National Laboratory (LANL); Herman, Micheal W [Brookhaven National Laboratory (BNL); Oblozinsky, Pavel [Brookhaven National Laboratory (BNL); Dunn, Michael E [ORNL; Danon, Y. [Rensselaer Polytechnic Institute (RPI); Kahler, A. [Los Alamos National Laboratory (LANL); Smith, Donald L. [Argonne National Laboratory (ANL); Pritychenko, B [Brookhaven National Laboratory (BNL); Arbanas, Goran [ORNL; Arcilla, r [Brookhaven National Laboratory (BNL); Brewer, R [Los Alamos National Laboratory (LANL); Brown, D A [Brookhaven National Laboratory (BNL); Capote, R. [International Atomic Energy Agency (IAEA); Carlson, A. D. [National Institute of Standards and Technology (NIST); Cho, Y S [Korea Atomic Energy Research Institute; Derrien, Herve [ORNL; Guber, Klaus H [ORNL; Hale, G. M. [Los Alamos National Laboratory (LANL); Hoblit, S [Brookhaven National Laboratory (BNL); Holloway, Shannon T. [Los Alamos National Laboratory (LANL); Johnson, T D [Brookhaven National Laboratory (BNL); Kawano, T. [Los Alamos National Laboratory (LANL); Kiedrowski, B C [Los Alamos National Laboratory (LANL); Kim, H [Korea Atomic Energy Research Institute; Kunieda, S [Los Alamos National Laboratory (LANL); Larson, Nancy M [ORNL; Leal, Luiz C [ORNL; Lestone, J P [Los Alamos National Laboratory (LANL); Little, R C [Los Alamos National Laboratory (LANL); Mccutchan, E A [Brookhaven National Laboratory (BNL); Macfarlane, R E [Los Alamos National Laboratory (LANL); MacInnes, M [Los Alamos National Laboratory (LANL); Matton, C M [Lawrence Livermore National Laboratory (LLNL); Mcknight, R D [Argonne National Laboratory (ANL); Mughabghab, S F [Brookhaven National Laboratory (BNL); Nobre, G P [Brookhaven National Laboratory (BNL); Palmiotti, G [Idaho National Laboratory (INL); Palumbo, A [Brookhaven National Laboratory (BNL); Pigni, Marco T [ORNL; Pronyaev, V. G. [Institute of Physics and Power Engineering (IPPE), Obninsk, Russia; Sayer, Royce O [ORNL; Sonzogni, A A [Brookhaven National Laboratory (BNL); Summers, N C [Lawrence Livermore National Laboratory (LLNL); Talou, P [Los Alamos National Laboratory (LANL); Thompson, I J [Lawrence Livermore National Laboratory (LLNL); Trkov, A. [Jozef Stefan Institute, Slovenia; Vogt, R L [Lawrence Livermore National Laboratory (LLNL); Van der Marck, S S [Nucl Res & Consultancy Grp, Petten, Netherlands; Wallner, A [University of Vienna, Austria; White, M C [Los Alamos National Laboratory (LANL); Wiarda, Dorothea [ORNL; Young, P C [Los Alamos National Laboratory (LANL)

2011-01-01T23:59:59.000Z

372

On numerical relations playing a role in nuclear fission  

E-Print Network (OSTI)

The key numbers useful for describing the fission process are the mass number of the primordial cluster of the fissioning system and the magic mass numbers 82 and 126 of the nascent light and heavy fragments. The mean mass number and the mean atomic number of the light fragments are linked to the mass number and to the atomic number of the primordial cluster by simple relationships. The value 54 of the mean atomic number of the heavy fragments is predicted by the nucleon phase model.

G. Mouze; C. Ythier

2012-01-18T23:59:59.000Z

373

ON THE NUMBER OF NEUTRONS FROM SOME FISSION FRAGMENTS  

SciTech Connect

The number of neutrons emitted by individual fragments from U/sup 235/ fission by thermal neutrons was measured using a large detector filled with a liquid organic cadmiumcontaining scintillator. The numbers of prompt neutrons were measured under 4 pi geometry conditions as a function of fragment mass. The excitation energy spent on prompt neutrons was derived on the basis of Weizsacker's semiempirical formula. A sharp asymmetry was noticed in the distribution of excitation energies between heavy and light fragments. The new data do not agree with the Fong statistical fission theory. (tr-auth)

Apalin, V.F.; Dobrynin, Yu.P.; Zakharova, V.P.; Kutikov, I.E.; Mikaelyan, L.A.

1960-01-01T23:59:59.000Z

374

Distribution of independent fission-product yields to isomeric states  

SciTech Connect

A simple one-parameter model is presented for calculating the distribution of independent yield strength between ground and isomeric states of primary fission products formed by neutron-induced fission of actinide nuclei. Yield branching ratios are calculated as a function of neutron energy (thermal, fast, and 14-MeV) for 144 nuclides having isomeric states with T/sub 1/2/ greater than or equal to 0.1 s. The results are proposed for use in the ENDF/B-V yield files.

Madland, D.G.; England, T.R.

1976-11-01T23:59:59.000Z

375

DOE Science Showcase - Fission Theory | OSTI, US Dept of Energy, Office of  

Office of Scientific and Technical Information (OSTI)

Fission Theory Fission Theory A predictive theory of nuclear fission has eluded physicists since 1939. Because understanding the fission process is crucial for many areas of scientific research, including particle systems, the development of carbon-free energy and to national security, much work continues at the Department of Energy (DOE) to understand fission's inherent complexity. Today, scientists are performing new experiments and using both microscopic and macroscopic-microscopic models of fission to help them in this quest. Read more about remarkable advances in the Department's fission theory research In the OSTI Collections: Fission Theory by Dr. William Watson, Physicist, OSTI staff. Image Credit: Los Alamos National Laboratory Additional Links of Interest Office of Nuclear Energy, DOE

376

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

377

A Model for Water Factor Measurements With Fission-Neutron Logging...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

A Model for Water Factor Measurements With Fission-Neutron Logging Tools (May 1983) A Model for Water Factor Measurements With Fission-Neutron Logging Tools (May 1983) A Model for...

378

1H, 15N, and 13C chemical shift assignments of neuronal calcium sensor-1 homolog from fission yeast  

E-Print Network (OSTI)

Keywords NCS Á Ncs1p Á Fission yeast Á Calcium Á EF-hand ÁTakeda K, Ames JB (2004) Fission yeast homolog of neuronal

Lim, Sunghyuk; Ames, James B.

2009-01-01T23:59:59.000Z

379

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… (more)

Reed, Mark Wilbert

2011-01-01T23:59:59.000Z

380

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

SciTech Connect

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

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

Fusion-Fission Hybrid Using a D-D Cylindrical Inertial Electrostatic Confinement (IEC) Driver  

Science Conference Proceedings (OSTI)

Fusion-Fission Hybrids and Transmutation / Proceedings of the Fifteenth International Conference on Emerging Nuclear Energy Systems

George H. Miley; Bradley Boyer

382

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

DOE Green Energy (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

383

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

DOE Green Energy (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

384

Basics of Fusion-Fission Research Facility (FFRF) as a Fusion Neutron Source  

Science Conference Proceedings (OSTI)

Fusion-Fission Hybrids and Transmutation / Proceedings of the Fifteenth International Conference on Emerging Nuclear Energy Systems

Leonid E. Zakharov

385

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

Science Conference Proceedings (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

386

The Project of Fusion-Fission Hybrid Energy Reactor in China  

Science Conference Proceedings (OSTI)

Fusion-Fission Hybrids and Transmutation / Proceedings of the Fifteenth International Conference on Emerging Nuclear Energy Systems

Maosheng Li; Rong Liu; Xueming Shi; Weiwei Yi; Yaosong Shen; Xianjue Peng

387

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

Science Conference Proceedings (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

388

Light ternary fission products: probabilities and charge distributions. [Reviews, data systematics  

SciTech Connect

A survey was made of experimental information pertinent to the probability of ternary fission and the charge distribution of the light ternary fission products. A new prescription is presented for the ternary fission probability as a function of incident particle energy and certain compound nucleus properties. Based upon systematics, a method for obtaining charge distributions of the light ternary products is presented.

Madland, D.G.; Stewart, L.

1977-04-01T23:59:59.000Z

389

A description of heavy ion induced fission based on diffusion model  

Science Conference Proceedings (OSTI)

In this talk a review on our recent work on fission theory from point of view of diffusion process is presented. The transient phenomena of fission rate are revealed and studied carefully. By comparison of the fission rate calculated both at the saddle and seission points

Wu Xizhen; Feng Renfa; Bao Jingdong; Sun Zemin; Zhuo Yizhong

1992-01-01T23:59:59.000Z

390

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

SciTech Connect

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

391

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

2007-05-16T23:59:59.000Z

392

Spallation-Fission Competition in Heaviest Elements; Helium Ion Induced Reactions in Plutonium Isotopes  

E-Print Network (OSTI)

Nuclear Energy Series, Plutonium Project Record, Vol. 1 4Nuclear Energy S e r i e s , Plutonium P r o j e c t RecordNuclear Energy S e r i e s , Plutonium P r o j e c t Record,

Glass, Richard A.; Carr, Robert J.; Cobble, James W.; Seaborg, Glenn T.

1956-01-01T23:59:59.000Z

393

Validation of MCNPX-PoliMi Fission Models  

Science Conference Proceedings (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

394

Pionic Radioactivity as New Mode of Nuclear Fission  

E-Print Network (OSTI)

In this paper a short review of the theoretical problems of the pionic radioactivity as a new nuclear mode is presented. The essential theoretical and experimental results obtained in the 25 years from the prediction of the nuclear pionic radioactivity are reviewed. Using the fission-like model it was shown that most of the SHE-nuclei lie in the region where the pionic fissility parameters attain their limiting value X=1 (see Fig.2-3). Hence, the SHE-region is characterized by the absence of a classical barrier toward spontaneous pion emission. Consequently, both decay modes, the pionic fission and the spontaneous fission of SHE nuclides, essentially will be determined only by shell effects. Then, it was seen that the usual predicted SHE-island of stability around the double magic nucleus 298-[114], which is not confirmed experimentally, can be explained by the dominant pionic radioactivity of the SHE-nuclei from this region. The bimodal symmetric (see Figs. 5ab) as well as, the supergiant radioactive halos (see Fig. 6) as two important signature of the nuclear pionic fission are evidentiated.

D. B. Ion; M. L. D. Ion; Reveica Ion-Mihai

2011-01-24T23:59:59.000Z

395

Title: WPEC Subgroup Proposal Prompt Photon Production from Fission Products  

E-Print Network (OSTI)

In a typical nuclear reactor some 10-12 % of heating comes from the energy deposited by gamma rays. The major photon production sources (equal proportions) are:- prompt neutron induced fission, capture of prompt neutrons, and the decay of fission plus activation daughter products. The photons penetrate some distance from their birth and can cause some 80-90 % of heating in non-fissile regions. This can lead to distortion of control rods and chemical damage in moderators, e.g. enhancing graphite erosion rate. There is considerable interest in extending fuel life (deep burn) and this in turn leads to more higher actinides and more FISSION PRODUCTS (nuclides with Z=35-70). A survey (of JEFF3.0, ENDF/B-VIr8 and JENDL3.3) in 2003 indicated very few modern evaluations in the mass range of fission products contain gamma source data. Where data are present they are often old and incomplete. At the completion of WPEC sub-group 23, a comprehensive and validated file of neutron cross sections will be ready for inclusion in modern libraries. This would form an ideal base that could be extended to include source information for production of prompt gammas.

Short Justification For A Subgroup; Jeff C J Dean

2006-01-01T23:59:59.000Z

396

Downstream Behavior of Volatile Iodine, Cesium, and Tellurium Fission Products  

Science Conference Proceedings (OSTI)

A better understanding of how iodine, cesium, and tellurium fission products deposit on primary reactor components during a degraded core accident can help utility analysts improve computer codes that model product behavior. The mathematical model developed in this study predicts the behavior of deposited products vaporized or revaporized by self-heating in a reactor accident.

1989-01-17T23:59:59.000Z

397

Fission Cycling in a Supernova r-process  

E-Print Network (OSTI)

Recent halo star abundance observations exhibit an important feature of consequence to the r-process: the presence of a main r-process between the second and third peaks which is consistent among halo stars. We explore fission cycling and steady-beta flow as the driving mechanisms behind this feature. The presence of fission cycling during the r-process can account for nucleosynthesis yields between the second and third peaks, whereas the presence of steady-beta flow can account for consistent r-process patterns, robust under small variations in astrophysical conditions. We employ the neutrino-driven wind of the core-collapse supernova to examine fission cycling and steady-beta flow in the r-process. As the traditional neutrino-driven wind model does not produce the required very neutron-rich conditions for these mechanisms, we examine changes to the neutrino physics necessary for fission cycling to occur in the neutrino-driven wind environment, and we explore under what conditions steady-beta flow is obtained.

J. Beun; G. C. McLaughlin; R. Surman; W. R. Hix

2007-07-30T23:59:59.000Z

398

THERMAL FISSION REACTOR COMPOSITIONS AND METHOD OF FABRICATING SAME  

DOE Patents (OSTI)

A body is presented for use in a thermal fission reactor comprising a sintered compressed mass of a substance of the group consisting of uranium, thorium, and oxides and carbides of uranium and thorium, enclosed in an envelope of a sintered, compacted, heat-conductive material of the group consisting of beryllium, zirconium, and oxides and carbides of beryllium and zirconium.

Blainey, A.

1959-10-01T23:59:59.000Z

399

SEPARATION OF PLUTONIUM FROM URANIUM AND FISSION PRODUCTS BY ADSORPTION  

DOE Patents (OSTI)

A method is presented for the separation of plutonium from solutions containing that element in a valence state not higher than 41 together with uranium ions and fission products. This separation is accomplished by contacting the solutions with diatomaceous earth which preferentially adsorbs the plutonium present. Also mentioned as effective for this adsorbtive separation are silica gel, filler's earth and alumina.

Seaborg, G.T.; Willard, J.E.

1958-01-01T23:59:59.000Z

400

Perspective on the fusion-fission hybrid reactor  

SciTech Connect

The hybrid reactor's role as a source of fuel for fission converter reactors is investigated. The role of the hybrid reactor in the energy economy, the interface between the hybrid reactor and the present fusion program, implications of the Carter Energy Plan, and the rationale for further hybrid reactor studies are discussed.

Bender, D.J.; Lee, J.D.; Moir, R.W.

1977-10-01T23:59:59.000Z

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

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

402

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

403

Piglet and the Pumpkin Field - Argonne's Nuclear Science and...  

NLE Websites -- All DOE Office Websites (Extended Search)

scientists describe the historic events which brought them to understand nuclear fission Anniversary - 80 years ago, Leo Szilard envisioned neutron chain reaction blog...

404

DOE - Office of Legacy Management -- Columbia University - NY...  

Office of Legacy Management (LM)

NY.03-3 Site Operations: Early research and development -- nuclear chain reaction (fission) and gaseous diffusion during the 1940s. NY.03-4 Site Disposition: Eliminated -...

405

Nuclear Design of the HOMER-15 Mars Surface Fission Reactor  

Science Conference Proceedings (OSTI)

The next generation of robotic missions to Mars will most likely require robust power sources in the range of 3 to 20 kWe. Fission systems are well suited to provide safe, reliable, and economic power within this range. The goal of this study is to design a compact, low-mass fission system that meets Mars surface power requirements, while maintaining a high level of safety and reliability at a relatively low cost. The Heat pipe Power System (HPS) is one possible approach for producing near-term, low-cost, space fission power. The goal of the HPS project is to devise an attractive space fission system that can be developed quickly and affordably. The primary ways of doing this are by using existing technology and by designing the system for inexpensive testing. If the system can be designed to allow highly prototypic testing with electrical heating, then an exhaustive test program can be carried out quickly and inexpensively, and thorough testing of the actual flight unit can be performed - which is a major benefit to reliability. Over the past 4 years, three small HPS proof-of-concept technology demonstrations have been conducted, and each has been highly successful. The Heat pipe-Operated Mars Exploration Reactor (HOMER) is a derivative of the HPS designed especially for producing power on the surface of Mars. The HOMER-15 is a 15-kWt reactor that couples with a 3-kWe Stirling engine power system. The reactor contains stainless-steel (SS)-clad uranium nitride (UN) fuel pins that are structurally and thermally bonded to SS/sodium heat pipes. Fission energy is conducted from the fuel pins to the heat pipes, which then carry the heat to the Stirling engine. This paper describes conceptual design and nuclear performance the HOMER-15 reactor. (author)

Poston, David I. [Nuclear Systems Design Group, Decision Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States)

2002-07-01T23:59:59.000Z

406

CHAIN REACTING SYSTEM  

DOE Patents (OSTI)

A nuclear reactor of the gas-cooled, graphitemoderated type is described. In this design, graphite blocks are arranged in a substantially cylindrical lattice having vertically orienied coolant channels in which uranium fuel elements having through passages are disposed. The active lattice is contained within a hollow body. such as a steel shell, which, in turn, is surrounded by water and concrete shields. Helium is used as the primary coolant and is circulated under pressure through the coolant channels and fuel elements. The helium is then conveyed to heat exchangers, where its heat is used to produce steam for driving a prime mover, thence to filtering means where radioactive impurities are removed. From the filtering means the helium passes to a compressor and an after cooler and is ultimately returned to the reactor for recirculation. Control and safety rods are provided to stabilize or stop the reaction. A space is provided between the graphite lattice and the internal walls of the shell to allow for thermal expansion of the lattice during operation. This space is filled with a resilient packing, such as asbestos, to prevent the passage of helium.

Fermi, E.; Leverett, M.C.

1958-06-01T23:59:59.000Z

407

Short-lived fission product measurements from >0.1 MeV neutron-induced fission using boron carbide.  

Science Conference Proceedings (OSTI)

A boron carbide shield was designed, custom fabricated, and used to create a fast fission energy neutron spectrum. The fissionable isotopes 233, 235, 238U, 237Np, and 239Pu were separately placed inside of this shield and irradiated under pulsed conditions at the Washington State University 1 MW TRIGA reactor. A unique set of fission product gamma spectra were collected at short times (4 minutes to 1 week) post-fission. Gamma spectra were collected on single-crystal high purity germanium detectors and on Pacific Northwest National Laboratory's (PNNL's) Direct Simultaneous Measurement (DSM) system composed of HPGe detectors connected in coincidence. This work defines the experimental methods used to produce and collect the gamma data, and demonstrates the validity of the measurements. It is important to fully document this information so the data can be used with high confidence for the advancement of nuclear science and non-proliferation applications. The gamma spectra collected in these and other experiments will be made publicly available at https://spcollab.pnl.gov/sites/gammadata or via the link at http://rdnsgroup.pnl.gov. A revised version of this publication will be posted with the data to make the experimental details available to those using the data.

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

2012-02-01T23:59:59.000Z

408

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

409

Event detection using trigger chain  

Science Conference Proceedings (OSTI)

This paper describes a new architecture for event detection from text documents. The proposed system correctly identifies the sentences that describe an event of interest, using trigger chain to extract its participants. It exploits supervised method ...

S. Sangeetha; R. S. Thakur; Michael Arock

2012-01-01T23:59:59.000Z

410

Lexical chains for question answering  

Science Conference Proceedings (OSTI)

The paper presents a method for finding topically related words on an extended WordNet. By exploiting the information in the WordNet glosses, the connectivity between the synsets is dramatically increased. Topical relations expressed as lexical chains ...

Dan Moldovan; Adrian Novischi

2002-08-01T23:59:59.000Z

411

Chain Transfer of Vegetable Oil Macromonomers in Acrylic Solution Copolymerization  

Science Conference Proceedings (OSTI)

Use of vegetable oil macromonomers (VOMMs) as comonomers in emulsion polymerization enables good film coalescence without the addition of solvents that constitute volatile organic compounds (VOCs). VOMMs are derived from renewable resources and offer the potential of post-application crosslinking via auto-oxidation. However, chain transfer reactions of VOMMs with initiator and/or polymer radicals during emulsion polymerization reduce the amount of allylic hydrogen atoms available for primary auto-oxidation during drying. Vegetable oils and derivatives were reacted in combination with butyl acrylate and methyl methacrylate via solution polymerization. The copolymerization was monitored using in situ infrared spectroscopy to determine the extent of chain transfer. 1H NMR spectroscopy was used to determine the loci of chain transfer and the molecular weight characteristics of the polymers were characterized by SEC. Solution polymerization was utilized to minimize temperature fluctuations and maintain polymer solubility during the initial characterization.

Black, Micah [University of Southern Mississippi, The; Messman, Jamie M [ORNL; Rawlins, James [University of Southern Mississippi, The

2011-01-01T23:59:59.000Z

412

Spontaneous fission lifetimes from the minimization of self-consistent collective action  

E-Print Network (OSTI)

The spontaneous fission lifetime of 264Fm has been studied within nuclear density functional theory by minimizing the collective action integral for fission in a two-dimensional quadrupole collective space representing elongation and triaxiality. The collective potential and inertia tensor are obtained self-consistently using the Skyrme energy density functional and density-dependent pairing interaction. The resulting spontaneous fission lifetimes are compared with the static result obtained with the minimum-energy pathway. We show that fission pathways strongly depend on assumptions underlying collective inertia. With the non-perturbative mass parameters, the dynamic fission pathway becomes strongly triaxial and it approaches the static fission valley. On the other hand, when the standard perturbative cranking inertia tensor is used, axial symmetry is restored along the path to fission; an effect that is an artifact of the approximation used.

Jhilam Sadhukhan; K. Mazurek; A. Baran; J. Dobaczewski; W. Nazarewicz; J. A. Sheikh

2013-10-08T23:59:59.000Z

413

Fission of heavy $?$ hypernuclei with the Skyrme-Hartree-Fock approach  

E-Print Network (OSTI)

Fission-related phenomena of heavy $\\Lambda$ hypernuclei are discussed with the constraint Skyrme-Hartree-Fock+BCS (SHF+BCS) method, in which a similar Skyrme-type interaction is employed also for the interaction between a $\\Lambda$ particle and a nucleon. Assuming that the $\\Lambda$ particle adiabatically follows the fission motion, we discuss the fission barrier height of $^{239}_{\\Lambda}$U. We find that the fission barrier height increases slightly when the $\\Lambda$ particle occupies the lowest level. In this case, the $\\Lambda$ particle is always attached to the heavier fission fragment. This indicates that one may produce heavy neutron-rich $\\Lambda$ hypernuclei through fission, whose weak decay is helpful for the nuclear transmutation of long-lived fission products. We also discuss cases where the $\\Lambda$ particle occupies a higher single-particle level.

F. Minato; S. Chiba; K. Hagino

2009-09-04T23:59:59.000Z

414

Bulk and surface controlled diffusion of fission gas atoms  

Science Conference Proceedings (OSTI)

Fission gas retention and release impact nuclear fuel performance by, e.g., causing fuel swelling leading to mechanical interaction with the clad, increasing the plenum pressure and reducing the gap thermal conductivity. All of these processes are important to understand in order to optimize operating conditions of nuclear reactors and to simulate accident scenarios. Most fission gases have low solubility in the fuel matrix, which is especially pronounced for large fission gas atoms such as Xe and Kr, and as a result there is a significant driving force for segregation of gas atoms to extended defects such as grain boundaries or dislocations and subsequently for nucleation of gas bubbles at these sinks. Several empirical or semi-empirical models have been developed for fission gas release in nuclear fuels, e.g. [1-6]. One of the most commonly used models in fuel performance codes was published by Massih and Forsberg [3,4,6]. This model is similar to the early Booth model [1] in that it applies an equivalent sphere to separate bulk UO{sub 2} from grain boundaries represented by the sphere circumference. Compared to the Booth model, it also captures trapping at grain boundaries, fission gas resolution and it describes release from the boundary by applying timedependent boundary conditions to the circumference. In this work we focus on the step where fission gas atoms diffuse from the grain interior to the grain boundaries. The original Massih-Forsberg model describes this process by applying an effective diffusivity divided into three temperature regimes. In this report we present results from density functional theory calculations (DFT) that are relevant for the high (D{sub 3}) and intermediate (D{sub 2}) temperature diffusivities of fission gases. The results are validated by making a quantitative comparison to Turnbull's [8-10] and Matzke's data [12]. For the intrinsic or high temperature regime we report activation energies for both Xe and Kr diffusion in UO{sub 2{+-}x}, which compare favorably to available experiments. This is an extension of previous work [13]. In particular, it applies improved chemistry models for the UO{sub 2{+-}x} nonstoichiometry and its impact on the fission gas activation energies. The derivation of these models follows the approach that used in our recent study of uranium vacancy diffusion in UO{sub 2} [14]. Also, based on the calculated DFT data we analyze vacancy enhanced diffusion mechanisms in the intermediate temperature regime. In addition to vacancy enhanced diffusion we investigate species transport on the (111) UO{sub 2} surface. This is motivated by the formation of small voids partially filled with fission gas atoms (bubbles) in UO{sub 2} under irradiation, for which surface diffusion could be the rate-limiting transport step. Diffusion of such bubbles constitutes an alternative mechanism for mass transport in these materials.

Andersson, Anders D. [Los Alamos National Laboratory

2012-08-09T23:59:59.000Z

415

Neutron Transport and Nuclear Burnup Analysis for the Laser Inertial Confinement Fusion-Fission Energy (LIFE) Engine  

Science Conference Proceedings (OSTI)

Laser Fusion-Fission Hybrid / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)

Kevin J. Kramer; Jeffery F. Latkowski; Ryan P. Abbott; John K. Boyd; Jeffrey J. Powers; Jeffrey E. Seifried

416

The effect of inventory on supply chain.  

E-Print Network (OSTI)

?? Supply chain management addresses the management of materials and information across the entire chain from suppliers to producers, distributors, retailers, and customers. In the… (more)

Meng, Yue

2006-01-01T23:59:59.000Z

417

Fusion-Fission Hybrid for Fissile Fuel Production without Processing  

SciTech Connect

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

418

Meet the Challenge - Supply Chain | Data.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Meet the Challenge - Supply Chain Sustainable Supply Chains Submissions Let's Talk About Sustainable Supply Chain You are here Data.gov Communities Sustainable Supply Chain...

419

Asymptotic analysis of multiscale approximations to reaction networks  

E-Print Network (OSTI)

A reaction network is a chemical system involving multiple reactions and chemical species. Stochastic models of such networks treat the system as a continuous time Markov chain on the number of molecules of each species with reactions as possible transitions of the chain. In many cases of biological interest some of the chemical species in the network are present in much greater abundance than others and reaction rate constants can vary over several orders of magnitude. We consider approaches to approximation of such models that take the multiscale nature of the system into account. Our primary example is a model of a cell’s viral infection for which we apply a combination of averaging and law of large number arguments to show that the “slow ” component of the model can be approximated by a deterministic equation and to characterize the asymptotic distribution of the “fast ” components. The main goal is to illustrate techniques that can be used to reduce the dimensionality of much more complex models. 1. Stochastic models for reaction networks. A reaction network is a chemical system involving multiple reactions and chemical species. The simplest stochastic model for a network treats the system as a continuous time Markov chain whose state X is a vector giving the number of molecules of each species present with each reaction modeled as a possible transition for the state. The model for the kth reaction is determined by a vector of inputs ?k specifying the number of molecules of each chemical species that are

Karen Ball; Thomas G. Kurtz; Lea Popovic; Greg Rempala

1961-01-01T23:59:59.000Z

420

September 2013 Most Viewed Documents for Fission And Nuclear Technologies |  

Office of Scientific and Technical Information (OSTI)

Fission And Nuclear Technologies Fission And Nuclear Technologies Estimation of gas leak rates through very small orifices and channels. [From sealed PuO/sub 2/ containers under accident conditions] Bomelburg, H.J. (1977) 133 Stress analysis and evaluation of a rectangular pressure vessel. [For equipment for sampling Hanford tank radwaste] Rezvani, M.A.; Ziada, H.H. (Westinghouse Hanford Co., Richland, WA (United States)); Shurrab, M.S. (Westinghouse Savannah River Co., Aiken, SC (United States)) (1992) 78 Graphite design handbook Ho, F.H. (1988) 76 Feed-pump hydraulic performance and design improvement, Phase I: research program design. Final report Brown, W.H.; Gopalakrishnan, S.; Fehlau, R.; Thompson, W.E.; Wilson, D.G. (1982) 69 Flow-induced vibration of circular cylindrical structures Chen, S.S. (1985)

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

April 2013 Most Viewed Documents for Fission And Nuclear Technologies |  

Office of Scientific and Technical Information (OSTI)

April 2013 Most Viewed Documents for Fission And Nuclear Technologies April 2013 Most Viewed Documents for Fission And Nuclear Technologies Behavior of spent nuclear fuel in water pool storage Johnson, A.B. Jr. (null) 298 Estimation of gas leak rates through very small orifices and channels. [From sealed PuO/sub 2/ containers under accident conditions] Bomelburg, H.J. (null) 292 Graphite design handbook Ho, F.H. (1988) 216 System Definition and Analysis: Power Plant Design and Layout NONE (1996) 123 Flow-induced vibration of circular cylindrical structures Chen, S.S. (1985) 116 Stress analysis and evaluation of a rectangular pressure vessel. [For equipment for sampling Hanford tank radwaste] Rezvani, M.A.; Ziada, H.H. (Westinghouse Hanford Co., Richland, WA (United States)); Shurrab, M.S. (Westinghouse Savannah River Co., Aiken, SC (United

422

Fission-Based Electric Propulsion for Interstellar Precursor Missions  

DOE Green Energy (OSTI)

This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total {Delta}V of more than 100 km/s in less than a decade of thrusting with an electric propulsion system of 10,000s Isp requires a specific mass for the power system of less than 35 kg/kWe. Three possible configurations are described: (1) a UZrH-fueled,NaK-cooled reactor with a steam Rankine conversion system,(2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heat pipe-cooled reactor with a recuperated Brayton conversion system. All three of these systems have the potential to meet the specific mass requirements for interstellar precursor missions in the near term. Advanced versions of a fission-based electric propulsion system might travel as much as several light years in 200 years.

HOUTS,MICHAEL G.; LENARD,ROGER X.; LIPINSKI,RONALD J.; PATTON,BRUCE; POSTON,DAVID; WRIGHT,STEVEN A.

1999-11-03T23:59:59.000Z

423

Advanced fission and fossil plant economics-implications for fusion  

Science Conference Proceedings (OSTI)

In order for fusion energy to be a viable option for electric power generation, it must either directly compete with future alternatives or serve as a reasonable backup if the alternatives become unacceptable. This paper discusses projected costs for the most likely competitors with fusion power for baseload electric capacity and what these costs imply for fusion economics. The competitors examined include advanced nuclear fission and advanced fossil-fired plants. The projected costs and their basis are discussed. The estimates for these technologies are compared with cost estimates for magnetic and inertial confinement fusion plants. The conclusion of the analysis is that fusion faces formidable economic competition. Although the cost level for fusion appears greater than that for fission or fossil, the costs are not so high as to preclude fusion`s potential competitiveness.

Delene, J.G.

1994-09-01T23:59:59.000Z

424

Analysis of the lumped fission-product uncertainty in CRBR  

Science Conference Proceedings (OSTI)

An approximation made in most fast reactor analyses is to utilize a single lumped fission product (FP) cross-section set to represent the total effect of the approximately 800 possible fission product nuclides in a depleted reactor model. Recent investigations have analyzed several aspects of this one-lump approximation (burnup dependence, comparison with a two-lump model, etc.), but little has been done in addressing the quality, or uncertainty, in the basic cross-section data utilized in any such representation. Thus, the purpose of this study is to investigate the uncertainty in the FP reactivity effect due to the data uncertainties inherent in an ENDF/B-V composite FP representation specifically designed for application with the current CRBR heterogeneous core concept.

White, J.R.; Schenter, R.E.

1981-01-01T23:59:59.000Z

425

Fission process of low excited nuclei with Langevin approach  

E-Print Network (OSTI)

Fragment mass distributions from the fission of U and Pu isotopes at low excitation energies are studied using a dynamical model based on the fluctuation-dissipation theorem formulated as Langevin equations. The present calculations reproduced the overall trend of the asymmetric mass distribution without parameter adjustment for the first time using the Langevin approach. The Langevin trajectories show a complicated time evolution on the potential surface, which causes the time delay of fission, showing that dynamical treatment is vital. It was found that the shell effect of the potential energy landscape has a dominant role in determining the mass distribution, although it is rather insensitive to the strength of dissipation. Nevertheless, it is essential to include the effect of dissipation, since it has a crucial role in giving "fluctuation" to Langevin trajectories as well as for explaining the multiplicities of pre-scission neutrons as the excitation energy increases. Therefore, the present approach can serve as a basis for more refined analysis.

Y. Aritomo; S. Chiba

2013-05-27T23:59:59.000Z

426

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

427

Experimental Neutron-Induced Fission Fragment Mass Yields of 232Th and 238U at Energies from 10 to 33 MeV  

E-Print Network (OSTI)

Development of nuclear energy applications requires data for neutron-induced reactions for actinides in a wide neutron energy range. Here we describe measurements of pre-neutron emission fission fragment mass yields of 232Th and 238U at incident neutron energies from 10 to 33 MeV. The measurements were done at the quasi-monoenergetic neutron beam of the Louvain-la-Neuve cyclotron facility CYCLONE; a multi-section twin Frisch-gridded ionization chamber was used to detect fission fragments. For the peak neutron energies at 33, 45 and 60 MeV, the details of the data analysis and the experimental results have been published before and in this work we present data analysis in the low-energy tail of the neutron energy spectra. The preliminary measurement results are compared with available experimental data and theoretical predictions.

V. D. Simutkin; S. Pomp; J. Blomgren; M. Österlund; R. Bevilacqua; I. V. Ryzhov; G. A. Tutin; S. G. Yavshits; L. A. Vaishnene; M. S. Onegin; J. P. Meulders; R. Prieels

2013-04-08T23:59:59.000Z

428

Discrimination between roles of fissioning nucleus and asymmetry degree of freedom on the even-odd structure in fission-fragment yields  

E-Print Network (OSTI)

Based on a wide systematics of fission-fragment distributions measured in low-energy fission, the even-odd staggering in the fission-fragment element yields is investigated. The well-established evolution of the global even-odd effect with the fissioning system is found to be only a partial aspect of the even-odd structure. Indeed, it is shown that the global even-odd effect is varying systematically with the mean asymmetry of the fission-fragment distribution, and that the general increase of the even-odd staggering with asymmetry is depending on the fissioning system. Thus, the dependency of the even-odd effect with the fissioning system is accredited in part to the asymmetry evolution of the charge distribution, and not solely related to the dissipated energy as it has been done earlier. This interpretation is strongly supported by data measured in inverse kinematics, which cover the complete charge distribution and include precise yields at symmetry. The relevance of the order parameter to describe the even-odd effect in fission-fragment yields as a general property is explored.

M. Caamano; F. Rejmund; K. -H. Schmidt

2009-09-05T23:59:59.000Z

429

Manhattan Project: The Discovery of Fission, 1938-1939  

Office of Scientific and Technical Information (OSTI)

Lise Meitner and Otto Hahn, Kaiser-Wilhelm Institute, Berlin THE DISCOVERY OF FISSION Berlin, Germany (1938-1939) Events > Atomic Discoveries, 1890s-1939 A Miniature Solar System, 1890s-1919 Exploring the Atom, 1919-1932 Atomic Bombardment, 1932-1938 The Discovery of Fission, 1938-1939 Fission Comes to America, 1939 The English word "atom" derives from the Greek word "atomon" ("ατομον"), which means "that which cannot be divided." In 1938, the scientific community proved the Greek philosophers wrong by dividing the atom. Excerpt from the comic book "Adventures Inside the Atom." Click on this image or visit the "Library" to view the whole comic book. Fission, the basis of the atomic bomb, was discovered in Nazi Germany less than a year before the beginning of the Second World War. It was December 1938 when the radiochemists Otto Hahn (above, with Lise Meitner) and Fritz Strassmann, while bombarding elements with neutrons in their Berlin laboratory, made their unexpected discovery. They found that while the nuclei of most elements changed somewhat during neutron bombardment, uranium nuclei changed greatly and broke into two roughly equal pieces. They split and became not the new transuranic elements that some thought Enrico Fermi had discovered but radioactive barium isotopes (barium has the atomic number 56) and other fragments of the uranium itself. The substances Fermi had created in his experiments, that is, did more than resemble lighter elements -- they were lighter elements. The products of the Hahn-Strassmann experiment weighed less than that of the original uranium nucleus, and herein lay the primary significance of their findings. It folIowed from Albert Einstein's E=mc2 equation that the loss of mass resulting from the splitting process must have been converted into energy in the form of kinetic energy that could in turn be converted into heat.

430

SPONTANEOUS PION EMISSION DURING FISSION A NEW NUCLEAR RADIOACTIVITY  

E-Print Network (OSTI)

In this paper a short review of the theoretical problems of the pionic radioactivity is presented. The essential experimental results obtained in the 18 years of existence of the nuclear pionic radioactivity are reviewed. Moreover, using the recent results on the spontaneous fission half lives TSF of the heavy nuclei with Z ? 100 new predictions on the pionic yields in the region of superheavy elements are established. 1

D. B. Ion; Reveica Ion-mihai; M. L. Ion; Adriana I. Sandru

2008-01-01T23:59:59.000Z

431

FUEL ELEMENTS FOR THERMAL-FISSION NUCLEAR REACTORS  

DOE Patents (OSTI)

Fuel elements for thermal-fission nuclear reactors are described. The fuel element is comprised of a core of alumina, a film of a metal of the class consisting of copper, silver, and nickel on the outer face of the core, and a coating of an oxide of a metal isotope of the class consisting of Un/sup 235/, U/ sup 233/, and Pu/sup 239/ on the metal f ilm.

Flint, O.

1961-01-10T23:59:59.000Z

432

Dating thermal events at Cerro Prieto using fission track annealing  

DOE Green Energy (OSTI)

Data from laboratory experiments and geologic fading studies were compiled from published sources to produce lines of iso-annealing for apatite in time-temperature space. Fission track ages were calculated for samples from two wells at Cerro Prieto, one with an apparently simple and one with an apparently complex thermal history. Temperatures were estimated by empirical vitrinite reflectance geothermometry, fluid inclusion homogenization and oxygen isotope equilibrium. These estimates were compared with logs of measured borehole temperatures.

Sanford, S.J.; Elders, W..

1981-01-01T23:59:59.000Z

433

Data summary report for fission product release test VI-6  

SciTech Connect

Test VI-6 was the sixth test in the VI series conducted in the vertical furnace. The fuel specimen was a 15.2-cm-long section of a fuel rod from the BR3 reactor in Belgium. The fuel had experienced a burnup of {approximately}42 MWd/kg, with inert gas release during irradiation of {approximately}2%. The fuel specimen was heated in an induction furnace at 2300 K for 60 min, initially in hydrogen, then in a steam atmosphere. The released fission products were collected in three sequentially operated collection trains designed to facilitate sampling and analysis. The fission product inventories in the fuel were measured directly by gamma-ray spectrometry, where possible, and were calculated by ORIGEN2. Integral releases were 75% for {sup 85}Kr, 67% for {sup 129}I, 64% for {sup 125}Sb, 80% for both {sup 134}Cs and {sup 137}Cs, 14% for {sup 154}Eu, 63% for Te, 32% for Ba, 13% for Mo, and 5.8% for Sr. Of the totals released from the fuel, 43% of the Cs, 32% of the Sb, and 98% of the Eu were deposited in the outlet end of the furnace. During the heatup in hydrogen, the Zircaloy cladding melted, ran down, and reacted with some of the UO{sub 2} and fission products, especially Te and Sb. The total mass released from the furnace to the collection system, including fission products, fuel, and structural materials, was 0.57 g, almost equally divided between thermal gradient tubes and filters. The release behaviors for the most volatile elements, Kr and Cs, were in good agreement with the ORNL Diffusion Model.

Osborne, M.F.; Lorenz, R.A.; Travis, J.R.; Webster, C.S.; Collins, J.L. [Oak Ridge National Lab., TN (United States)

1994-03-01T23:59:59.000Z

434

Fission Product Benchmarking for Burnup Credit Applications: Progress Report  

Science Conference Proceedings (OSTI)

Progress toward developing a technical basis for a cost-effective burnup credit methodology for spent nuclear fuel with initial U-235 enrichment up to 5 percent is presented. Present regulatory practices provide as much burnup credit flexibility as can be currently expected. Further progress is achievable by incorporating the negative reactivity effects of a subset of neutron-absorbing fission product isotopes. Progress also depends on optimizing the procedure for establishing the burnup characteristics ...

2002-12-03T23:59:59.000Z

435

Modeling of Molten Core Concrete Interactions and Fission Product Release  

Science Conference Proceedings (OSTI)

The study of molten core concrete interactions is important in estimating the possible consequences of a severe nuclear reactor accident. CORCON-Mod2 is a computer program that models the thermal, chemical, and physical phenomena associated with molten core concrete interactions. Models have been added to extend the modeling of these phenomena. An ideal solution chemical equilibrium methodology predicts the fission product vaporization release. Additional chemical species have been added, and the calcula...

1994-05-27T23:59:59.000Z

436

Robustness of quantum Markov chains  

E-Print Network (OSTI)

If the conditional information of a classical probability distribution of three random variables is zero, then it obeys a Markov chain condition. If the conditional information is close to zero, then it is known that the distance (minimum relative entropy) of the distribution to the nearest Markov chain distribution is precisely the conditional information. We prove here that this simple situation does not obtain for quantum conditional information. We show that for tri-partite quantum states the quantum conditional information is always a lower bound for the minimum relative entropy distance to a quantum Markov chain state, but the distance can be much greater; indeed the two quantities can be of different asymptotic order and may even differ by a dimensional factor.

Ben Ibinson; Noah Linden; Andreas Winter

2006-11-05T23:59:59.000Z

437

Sustainable Supply Chain | Data.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Sustainable Supply Chain Sustainable Supply Chain Sustainable Supply Chains Submissions Let's Talk About Sustainable Supply Chain Welcome to the Sustainable Supply Chain Community of Practice Bringing together government, industry, associations, non-profits and academic institutions to achieve more sustainable supply chains. Sustainable Supply Chain - New Updates New Updates View More Be a Champion Be a champion The Sustainable Supply Chain Community of Practice seeks champions from industry, academia and non-profits to lead each of the community market sectors. Do you know or are you a member of a leading edge organization that is implementing sustainable supply chain practices within one of the seven current community market sectors? If yes, nominate the organization as a Champion. Sustainable supply chain practices lead to cost savings,

438

Assessment of selected fission products in the Savannah River Site environment  

SciTech Connect

Most of the radioactivity produced by the operation of a nuclear reactor results from the fission process, during which the nucleus of a fissionable atom (such as 235U) splits into two or more nuclei, which typically are radioactive. The Radionuclide Assessment Program (RAP) has reported on fission products cesium, strontium, iodine, and technetium. Many other radionuclides are produced by the fission process. Releases of several additional fission products that result in dose to the offsite population are discussed in this publication. They are 95Zr, 95Nb, 103Ru, 106Ru, 141Ce, and 144Ce. This document will discuss the production, release, migration, and dose to humans for each of these selected fission products.

Carlton, W.H.; Denham, M.

1997-04-01T23:59:59.000Z

439

Fission time-scale in experiments and in multiple initiation model  

Science Conference Proceedings (OSTI)

Rate of fission for highly-excited nuclei is affected by the viscose character of the systemmotion in deformation coordinates as was reported for very heavy nuclei with Z{sub C} > 90. The long time-scale of fission can be described in a model of 'fission by diffusion' that includes an assumption of the overdamped diabatic motion. The fission-to-spallation ratio at intermediate proton energy could be influenced by the viscosity, as well. Within a novel approach of the present work, the cross examination of the fission probability, time-scales, and pre-fission neutron multiplicities is resulted in the consistent interpretation of a whole set of the observables. Earlier, different aspects could be reproduced in partial simulations without careful coordination.

Karamian, S. A., E-mail: karamian@nrmail.jinr.ru [Joint Institute for Nuclear Research (Russian Federation)

2011-12-15T23:59:59.000Z

440

An evaporation-based model of thermal neutron induced ternary fission of plutonium  

E-Print Network (OSTI)

Ternary fission probabilities for thermal neutron induced fission of plutonium are analyzed within the framework of an evaporation-based model where the complexity of time-varying potentials, associated with the neck collapse, are included in a simplistic fashion. If the nuclear temperature at scission and the fission-neck-collapse time are assumed to be ~1.2 MeV and ~10^-22 s, respectively, then calculated relative probabilities of ternary-fission light-charged-particle emission follow the trends seen in the experimental data. The ability of this model to reproduce ternary fission probabilities spanning seven orders of magnitude for a wide range of light-particle charges and masses implies that ternary fission is caused by the coupling of an evaporation-like process with the rapid re-arrangement of the nuclear fluid following scission.

J. P. Lestone

2007-03-10T23:59:59.000Z

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

Fission barriers in neutron-proton isospin plane for heavy neutron-rich nuclei  

E-Print Network (OSTI)

We discuss the sensitivity of fission barrier for heavy neutron-rich nuclei to fission paths in the two dimensional neutron-proton quadrupole plane. To this end, we use the constrained Skyrme-Hartree-Fock + BCS method, and examine the difference of fission barriers obtained with three constraining operators, that is, the neutron, proton, and mass quadrupole operators. We investigate $^{220}$U, $^{236}$U, and $^{266}$U, %from proton-rich to neutron-rich uranium isotopes, that is relevant to r-process nucleosynthesis. We find that the fission barrier heights are almost the same among the three constraining operators even for neutron-rich nuclei, indicating that the usual way to calculate fission barriers with the mass quadrupole operator is well justified. We also discuss the difference between proton and neutron deformation parameters along the fission paths.

F. Minato; K. Hagino

2008-02-19T23:59:59.000Z

442

Updated comparison of economics of fusion reactors with advanced fission reactors  

Science Conference Proceedings (OSTI)

The projected cost of electricity (COE) for fusion is compared with that from current and advanced nuclear fission and coal-fired plants. Fusion cost models were adjusted for consistency with advanced fission plants and the calculational methodology and cost factors follow guidelines recommended for cost comparisons of advanced fission reactors. The results show COEs of about 59--74 mills/kWh for the fusion designs considered. In comparison, COEs for future fission reactors are estimated to be in the 43--54 mills/kWh range with coal-fired plant COEs of about 53--69 mills/kWh ($2--3/GJ coal). The principal cost driver for the fusion plants relative to fission plants is the fusion island cost. Although the estimated COEs for fusion are greater than those for fission or coal, the costs are not so high as to preclude fusion's competitiveness as a safe and environmentally sound alternative.

Delene, J.G.

1990-01-01T23:59:59.000Z

443

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

SciTech Connect

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

444

Assessment of fission product yields data needs in nuclear reactor applications  

Science Conference Proceedings (OSTI)

Studies on the build-up of fission products in fast reactors have been performed, with particular emphasis on the effects related to the physics of the nuclear fission process. Fission product yields, which are required for burn-up calculations, depend on the proton and neutron number of the target nucleus as well as on the incident neutron energy. Evaluated nuclear data on fission product yields are available for all relevant target nuclides in reactor applications. However, the description of their energy dependence in evaluated data is still rather rudimentary, which is due to the lack of experimental fast fission data and reliable physical models. Additionally, physics studies of evaluated JEFF-3.1.1 fission yields data have shown potential improvements, especially for various fast fission data sets of this evaluation. In recent years, important progress in the understanding of the fission process has been made, and advanced model codes are currently being developed. This paper deals with the semi-empirical approach to the description of the fission process, which is used in the GEF code being developed by K.-H. Schmidt and B. Jurado on behalf of the OECD Nuclear Energy Agency, and with results from the corresponding author's diploma thesis. An extended version of the GEF code, supporting the calculation of spectrum weighted fission product yields, has been developed. It has been applied to the calculation of fission product yields in the fission rate spectra of a MOX fuelled sodium-cooled fast reactor. Important results are compared to JEFF-3.1.1 data and discussed in this paper. (authors)

Kern, K.; Becker, M.; Broeders, C. [Institut fuer Neutronenphysik und Reaktortechnik, KIT Campus Nord, Hermann-von-Helmholtz-Platz 1, 76344 Leopoldshafen (Germany)

2012-07-01T23:59:59.000Z

445

Neutron-flux profile monitor for use in a fission reactor  

DOE Patents (OSTI)

A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occurred. Neutron flux profiles of reactor cores can be more accurately measured as a result.

Kopp, M.K.; Valentine, K.H.

1981-09-15T23:59:59.000Z

446

FISSION HALF LIVES OF FERMIUM ISOTOPES WITHIN SKYRME HARTREE-FOCK-BOGOLIUBOV THEORY  

Science Conference Proceedings (OSTI)

Nuclear fission barriers, mass parameters and spontaneous fission half lives of fermium isotopes calculated in a framework of the Skyrme Hartree-Fock-Bogoliubov model with the SkM* force are discussed. Zero-point energy corrections in the ground state are determined for each nucleus using the Gaussian overlap approximation of the generator coordinate method and in the cranking formalism. Results of spontaneous fission half lives are compared to experimental data.

Baran, A. [Maria Curie-Sklodowska University; Staszczak, Andrzej [ORNL; Nazarewicz, A. [Oak Ridge National Laboratory (ORNL)

2011-01-01T23:59:59.000Z

447

PURIFICATION OF PLUTONIUM USING A CERIUM PRECIPITATE AS A CARRIER FOR FISSION PRODUCTS  

DOE Patents (OSTI)

Bismuth phosphate carrier precipitation processes are described for the separation of plutonium from fission products wherein in at least one step bismuth phosphate is precipitated in the presence of hexavalent plutonium thereby carrying a portion of the fission products from soluble plu tonium values. In this step, a cerium phosphate precipitate is formed in conjunction with the bismuth phosphate precipitate, thereby increasing the amount of fission products removed from solution.

Faris, B.F.; Olson, C.M.

1961-07-01T23:59:59.000Z

448

Automated reaction mapping  

Science Conference Proceedings (OSTI)

Automated reaction mapping is a fundamental first step in the analysis of chemical reactions and opens the door to the development of sophisticated chemical kinetic tools. This article formulates the reaction mapping problem as an optimization problem. ... Keywords: Cheminformatics, mechanisms

John D. Crabtree; Dinesh P. Mehta

2009-02-01T23:59:59.000Z

449

Phase-Field Simulation of Void and Fission-Gas Bubble Evolution in ...  

Science Conference Proceedings (OSTI)

Symposium, Mechanical Performance for Current and Next-Generation Nuclear Reactors. Presentation Title, Phase-Field Simulation of Void and Fission-Gas ...

450

Multi-Scale Modeling of Fission Gas Evolution in UO2  

Science Conference Proceedings (OSTI)

Fission gases in uranium dioxide (UO2) nuclear fuels, of which Xe is one of the most prominent, influence fuel performance during reactor operation and have ...

451

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

Science Conference Proceedings (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

452

UO 2 fission gas release rates from atomistic calculations of intrinsic ...  

Science Conference Proceedings (OSTI)

Based on DFT and empirical potential calculations, the diffusivity of fission gas atoms (Xe) in UO2 nuclear fuel has been calculated for a range of  ...

453

Kinetic Monte Carlo Study of Fission Gas and Grain Growth in ...  

Science Conference Proceedings (OSTI)

We have considered the effect of fission gas bubbles (primarily due to xenon and krypton) on the swelling of the nuclear fuel. Using an analytical model we have ...

454

Singlet Fission Holds Two-for-One Potential in Solar Cells (Fact...  

NLE Websites -- All DOE Office Websites (Extended Search)

confirmed the first molecular compound specifically designed to exhibit multiple- exciton generation through singlet fission-in effect, producing two electrons for every one photon...

455

Irradiation Effects on Fission Product Behavior in PyC and SiC  

Science Conference Proceedings (OSTI)

Abstract Scope, Understanding the mechanism and quantifying the rate by which fission products diffuse through CVD ?-silicon carbide (SiC) is crucial to the ...

456

Five-Dimensional Fission-Barrier Calulations from Se-70 to Cf-252  

E-Print Network (OSTI)

We present fission-barrier-height calculations for nuclei throught the Periodic Table based on a realistic macroscopic-microscopic model. Compared to other calculations: (1) we use a deformation space of sufficiently high dimension, sampled densely enough to describe the relevant topography of the fission potential, (2) we unambiguously find the physically relevant saddle points in this space, and (3) we formulate our model so that we obtain continuity of the potential energy at the division point between a single system and separated fission fragments or colliding nuclei, allowing us to (4) describe both fission-barrier heights and ground-state masses throughout the Periodic Table.

Peter Moller; Arnold J. Sierk; Akira Iwamoto

2004-01-27T23:59:59.000Z

457

/sup 3/He-induced fission of nuclei 159  

Science Conference Proceedings (OSTI)

The fission of nuclei with 159fission 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

458

Cost of Processing Fuel from a Molten Salt, Fusion/Fission, Hybrid Reactor Blanket  

Science Conference Proceedings (OSTI)

Blanket and Process Engineering / Proceedings of the Second National Topical Meeting on Tritium Technology in Fission, Fusion and Isotopic Applications (Dayton, Ohio, April 30 to May 2, 1985)

J. S. Watson; W. R. Grimes; D. E. Brashears

459

EMPIRE: Nuclear Reaction Model Code System for Data Evaluation  

SciTech Connect

EMPIRE is a modular system of nuclear reaction codes, comprising various nuclear models, and designed for calculations over a broad range of energies and incident particles. A projectile can be a neutron, proton, any ion (including heavy-ions) or a photon. The energy range extends from the beginning of the unresolved resonance region for neutron-induced reactions ({approx} keV) and goes up to several hundred MeV for heavy-ion induced reactions. The code accounts for the major nuclear reaction mechanisms, including direct, pre-equilibrium and compound nucleus ones. Direct reactions are described by a generalized optical model (ECIS03) or by the simplified coupled-channels approach (CCFUS). The pre-equilibrium mechanism can be treated by a deformation dependent multi-step direct (ORION + TRISTAN) model, by a NVWY multi-step compound one or by either a pre-equilibrium exciton model with cluster emission (PCROSS) or by another with full angular momentum coupling (DEGAS). Finally, the compound nucleus decay is described by the full featured Hauser-Feshbach model with {gamma}-cascade and width-fluctuations. Advanced treatment of the fission channel takes into account transmission through a multiple-humped fission barrier with absorption in the wells. The fission probability is derived in the WKB approximation within the optical model of fission. Several options for nuclear level densities include the EMPIRE-specific approach, which accounts for the effects of the dynamic deformation of a fast rotating nucleus, the classical Gilbert-Cameron approach and pre-calculated tables obtained with a microscopic model based on HFB single-particle level schemes with collective enhancement. A comprehensive library of input parameters covers nuclear masses, optical model parameters, ground state deformations, discrete levels and decay schemes, level densities, fission barriers, moments of inertia and {gamma}-ray strength functions. The results can be converted into ENDF-6 formatted files using the accompanying code EMPEND and completed with neutron resonances extracted from the existing evaluations. The package contains the full EXFOR (CSISRS) library of experimental reaction data that are automatically retrieved during the calculations. Publication quality graphs can be obtained using the powerful and flexible plotting package ZVView. The graphic user interface, written in Tcl/Tk, provides for easy operation of the system. This paper describes the capabilities of the code, outlines physical models and indicates parameter libraries used by EMPIRE to predict reaction cross sections and spectra, mainly for nucleon-induced reactions. Selected applications of EMPIRE are discussed, the most important being an extensive use of the code in evaluations of neutron reactions for the new US library ENDF/B-VII.0. Future extensions of the system are outlined, including neutron resonance module as well as capabilities of generating covariances, using both KALMAN and Monte-Carlo methods, that are still being advanced and refined.

Herman, M. [National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)], E-mail: mwherman@bnl.gov; Capote, R. [Nuclear Data Section, International Atomic Energy Agency, Wagramer Strasse, A-1400 Vienna (Austria); Carlson, B.V. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, 12228-900, SP, Sao Jose dos Campos (Brazil); Oblozinsky, P. [National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Sin, M. [Nuclear Physics Department, Bucharest University, P.O. Box MG-11, Bucharest-Magurele (Romania); Trkov, A. [Jozef Stefan Institute, Reactor Physics Division R-1, Jamova 39, 1000 Ljubljana (Slovenia); Wienke, H. [Belgonucleaire, Dessel, B2480 (Belgium); Zerkin, V. [Nuclear Data Section, International Atomic Energy Agency, Wagramer Strasse, A-1400 Vienna (Austria)

2007-12-15T23:59:59.000Z

460