National Library of Energy BETA

Sample records for hfir spallation neutron

  1. Neutron Irradiation of Hydrided Cladding Material in HFIR Summary...

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

    (HFIR). Irradiation of the capsules was conducted for post-irradiation examination (PIE) metallography. PDF icon Neutron Irradiation of Hydrided Cladding Material in HFIR...

  2. Spallation Neutron Source (SNS) | U.S. DOE Office of Science (SC)

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

    Neutron Scattering Facilities » Spallation Neutron Source (SNS) Scientific User Facilities (SUF) Division SUF Home About User Facilities X-Ray Light Sources Neutron Scattering Facilities Spallation Neutron Source (SNS) High Flux Isotope Reactor (HFIR) Nanoscale Science Research Centers (NSRCs) Projects Accelerator & Detector Research Science Highlights Principal Investigators' Meetings BES Home Neutron Scattering Facilities Spallation Neutron Source (SNS) Print Text Size: A A A

  3. HFIR and SNS Capabilities Continue to Grow (Journal Article)...

    Office of Scientific and Technical Information (OSTI)

    Country of Publication: United States Language: English Subject: 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 43 PARTICLE ACCELERATORS; HFIR REACTOR; SPALLATION; NEUTRON ...

  4. CHINA SPALLATION NEUTRON SOURCE DESIGN.

    SciTech Connect (OSTI)

    WEI,J.

    2007-01-29

    The China Spallation Neutron Source (CSNS) is an accelerator-based high-power project currently in preparation under the direction of the Chinese Academy of Sciences (CAS). The complex is based on an H- linear accelerator, a rapid cycling proton synchrotron accelerating the beam to 1.6 GeV, a solid tungsten target station, and five initial instruments for spallation neutron applications. The facility will operate at 25 Hz repetition rate with a phase-I beam power of about 120 kW. The major challenge is to build a robust and reliable user's facility with upgrade potential at a fractional of ''world standard'' cost.

  5. The Spallation Neutron Source (SNS) Project | Department of Energy

    Office of Environmental Management (EM)

    The Spallation Neutron Source (SNS) Project The Spallation Neutron Source (SNS) Project SNS03.31.10.pdf More Documents & Publications EIS-0247: Draft Environmental Impact...

  6. Spallation Neutron Source Power Level Exceeds 1 MW (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Spallation Neutron Source Power Level Exceeds 1 MW Citation Details In-Document Search Title: Spallation Neutron Source Power Level Exceeds 1 MW No abstract prepared. Authors: ...

  7. The Spallation Neutron Source: A powerful tool for materials...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: The Spallation Neutron Source: A powerful tool for materials research Citation Details In-Document Search Title: The Spallation Neutron Source: A powerful tool for ...

  8. Spallation Neutron Source reaches megawatt power

    SciTech Connect (OSTI)

    Dr. William F. Brinkman

    2009-09-30

    The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

  9. Spallation Neutron Source reaches megawatt power

    ScienceCinema (OSTI)

    Dr. William F. Brinkman

    2010-01-08

    The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

  10. January 16, 2009: Expansion of Spallation Neutron Source | Department of

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

    Energy 16, 2009: Expansion of Spallation Neutron Source January 16, 2009: Expansion of Spallation Neutron Source January 16, 2009: Expansion of Spallation Neutron Source January 16, 2009 The Department gives its initial approval to begin plans for the Oak Ridge National Laboratory (ORNL) to build a second target station for the Spallation Neutron Source, expanding what is already the world's most powerful pulsed neutron scattering facility. The new station, which will cost approximately $1

  11. High Flux Isotope Reactor (HFIR) | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Facilities » High Flux Isotope Reactor (HFIR) Scientific User Facilities (SUF) Division SUF Home About User Facilities X-Ray Light Sources Neutron Scattering Facilities Spallation Neutron Source (SNS) High Flux Isotope Reactor (HFIR) Nanoscale Science Research Centers (NSRCs) Projects Accelerator & Detector Research Science Highlights Principal Investigators' Meetings BES Home Neutron Scattering Facilities High Flux Isotope Reactor (HFIR) Print Text Size: A A A FeedbackShare Page Quick

  12. Spallation Neutron Source Radiation Shielding Issues

    SciTech Connect (OSTI)

    Azmy, Y.Y.; Barnes, J.M.; Drischler, J.D.; Johnston, J.O.; Lillie, R.A.; McNeilly, G.S.; Santoro, R.T.

    1999-11-14

    This paper summarizes results of Spallation Neutron Source calculations to estimate radiation hazards and shielding requirements for activated Mercury, target components, target cooling water, and {sup 7}Be plateout. Dose rates in the accelerator tunnel from activation of magnets and concrete were investigated. The impact of gaps and other streaming paths on the radiation environment inside the test cell during operation and after shutdown were also assessed.

  13. Neutron Production by Muon Spallation I: Theory (Technical Report...

    Office of Scientific and Technical Information (OSTI)

    Title: Neutron Production by Muon Spallation I: Theory We ... OSTI Identifier: 900172 Report Number(s): UCRL-TR-226323 ... Language: English Subject: 72 PHYSICS OF ELEMENTARY ...

  14. Materials Selection for the HFIR Cold Neutron Source

    SciTech Connect (OSTI)

    Farrell, K.

    2001-08-24

    In year 2002 the High Flux Isotope Reactor (HFIR) will be fitted with a source of cold neutrons to upgrade and expand its existing neutron scattering facilities. The in-reactor components of the new source consist of a moderator vessel containing supercritical hydrogen gas moderator at a temperature of 20K and pressure of 15 bar, and a surrounding vacuum vessel. They will be installed in an enlarged beam tube located at the site of the present horizontal beam tube, HB-4; which terminates within the reactor's beryllium reflector. These components must withstand exceptional service conditions. This report describes the reasons and factors underlying the choice of 6061-T6 aluminum alloy for construction of the in-reactor components. The overwhelming considerations are the need to minimize generation of nuclear heat and to remove that heat through the flowing moderator, and to achieve a minimum service life of about 8 years coincident with the replacement schedule for the beryllium reflector. 6061-T6 aluminum alloy offers the best combination of low nuclear heating, high thermal conductivity, good fabricability, compatibility with hydrogen, superior cryogenic properties, and a well-established history of satisfactory performance in nuclear environments. These features are documented herein. An assessment is given of the expected performance of each component of the cold source.

  15. Spallation Neutron Source | Neutron Science at ORNL

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

    The recently commissioned 11 Tesla horizontal field magnet at GP-SANS will enable advanced neutron scattering research. Credit: Genevieve MartinORNL. 11 Tesla Magnet Commissioned ...

  16. The European scene regarding spallation neutron sources

    SciTech Connect (OSTI)

    Bauer, G.S.

    1996-06-01

    In Europe, a short pulse spallation neutron source, ISIS, has been operating for over 10 years, working its way up to a beam power level of 200 kW. A continuous source, SINQ, designed for a beam power of up to 1 MW, is scheduled to start operating at the end of 1996, and a detailed feasibility study has been completed for a 410 kW short pulse source, AUSTRON. Each of these sources seems to have settled for a target concept which is at or near the limits of its feasibility: The ISIS depleted uranium plate targets, heavy water cooled and Zircaloy clad, have so far not shown satisfactory service time and operation is likely to continue with a Ta-plate target, which, in the past has been used successfully for the equivalent of one full-beam-year before it was taken out of service due to degrading thermal properties. SINQ will initially use a rod target, made of Zircaloy only, but plans exist to move on to clad lead rods as quickly as possible. Apart from the not yet explored effect of hydrogen and helium production, there are also concerns about the generation of 7-Be in the cooling water from the spallation of oxygen, which might result in undesirably high radioactivity in the cooling plant room. A Liquid metal target, also under investigation for SINQ, would not only reduce this problem to a level of about 10 %, but would also minimize the risk of radiolytic corrosion in the beam interaction zone. Base on similar arguments, AUSTRON has been designed for edge cooled targets, but thermal and stress analyses show, that this concept is not feasible at higher power levels.

  17. The Spallation Neutron Source Beam Commissioning and Initial Operations

    SciTech Connect (OSTI)

    Henderson, Stuart; Aleksandrov, Alexander V.; Allen, Christopher K.; Assadi, Saeed; Bartoski, Dirk; Blokland, Willem; Casagrande, F.; Campisi, I.; Chu, C.; Cousineau, Sarah M.; Crofford, Mark T.; Danilov, Viatcheslav; Deibele, Craig E.; Dodson, George W.; Feshenko, A.; Galambos, John D.; Han, Baoxi; Hardek, T.; Holmes, Jeffrey A.; Holtkamp, N.; Howell, Matthew P.; Jeon, D.; Kang, Yoon W.; Kasemir, Kay; Kim, Sang-Ho; Kravchuk, L.; Long, Cary D.; McManamy, T.; Pelaia, II, Tom; Piller, Chip; Plum, Michael A.; Pogge, James R.; Purcell, John David; Shea, T.; Shishlo, Andrei P; Sibley, C.; Stockli, Martin P.; Stout, D.; Tanke, E.; Welton, Robert F; Zhang, Y.; Zhukov, Alexander P

    2015-09-01

    The Spallation Neutron Source (SNS) accelerator delivers a one mega-Watt beam to a mercury target to produce neutrons used for neutron scattering materials research. It delivers ~ 1 GeV protons in short (< 1 us) pulses at 60 Hz. At an average power of ~ one mega-Watt, it is the highest-powered pulsed proton accelerator. The accelerator includes the first use of superconducting RF acceleration for a pulsed protons at this energy. The storage ring used to create the short time structure has record peak particle per pulse intensity. Beam commissioning took place in a staged manner during the construction phase of SNS. After the construction, neutron production operations began within a few months, and one mega-Watt operation was achieved within three years. The methods used to commission the beam and the experiences during initial operation are discussed.

  18. Oak Ridge Spallation Neutron Source (ORSNS) target station design integration

    SciTech Connect (OSTI)

    McManamy, T.; Booth, R.; Cleaves, J.; Gabriel, T.

    1996-06-01

    The conceptual design for a 1- to 3-MW short pulse spallation source with a liquid mercury target has been started recently. The design tools and methods being developed to define requirements, integrate the work, and provide early cost guidance will be presented with a summary of the current target station design status. The initial design point was selected with performance and cost estimate projections by a systems code. This code was developed recently using cost estimates from the Brookhaven Pulsed Spallation Neutron Source study and experience from the Advanced Neutron Source Project`s conceptual design. It will be updated and improved as the design develops. Performance was characterized by a simplified figure of merit based on a ratio of neutron production to costs. A work breakdown structure was developed, with simplified systems diagrams used to define interfaces and system responsibilities. A risk assessment method was used to identify potential problems, to identify required research and development (R&D), and to aid contingency development. Preliminary 3-D models of the target station are being used to develop remote maintenance concepts and to estimate costs.

  19. SPALLATION NEUTRON SOURCE RING-DESIGN AND CONSTRUCTION SUMMARY.

    SciTech Connect (OSTI)

    WEI,J.

    2005-05-16

    After six years, the delivery of components for the Spallation Neutron Source (SNS) accumulator ring (AR) and the transport lines was completed in Spring 2005. Designed to deliver 1.5 MW beam power (1.5 x 10{sup 14} protons of 1 GeV kinetic energy at a repetition rate of 60 Hz), stringent measures were implemented in the fabrication, test, and assembly to ensure the quality of the accelerator systems. This paper summarizes the design, R&D, and construction of the ring and transport systems.

  20. The Macromolecular Neutron Diffractometer MaNDi at the Spallation Neutron Source

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Coates, Leighton; Cuneo, Matthew J.; Frost, Matthew J.; He, Junhong; Weiss, Kevin L.; McFeeters, Hana; Tomanicek, Stephen J.; Vandavasi, Venu Gopal; Langan, Paul; Iverson, Erik B.

    2015-07-18

    The Macromolecular Neutron Diffractometer (MaNDi) is located on beamline 11B of the Spallation Neutron Source at Oak Ridge National Laboratory. Moreover, the instrument is a neutron time-of-flight wavelength-resolved Laue diffractometer optimized to collect diffraction data from single crystals. Finally, the instrument has been designed to provide flexibility in several instrumental parameters, such as beam divergence and wavelength bandwidth, to allow data collection from a range of macromolecular systems.

  1. The Macromolecular Neutron Diffractometer MaNDi at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Coates, Leighton; Cuneo, Matthew J.; Frost, Matthew J.; He, Junhong; Weiss, Kevin L.; McFeeters, Hana; Tomanicek, Stephen J.; Vandavasi, Venu Gopal; Langan, Paul; Iverson, Erik B.

    2015-07-18

    The Macromolecular Neutron Diffractometer (MaNDi) is located on beamline 11B of the Spallation Neutron Source at Oak Ridge National Laboratory. Moreover, the instrument is a neutron time-of-flight wavelength-resolved Laue diffractometer optimized to collect diffraction data from single crystals. Finally, the instrument has been designed to provide flexibility in several instrumental parameters, such as beam divergence and wavelength bandwidth, to allow data collection from a range of macromolecular systems.

  2. Optimizing Moderator Dimensions for Neutron Scattering at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Zhao, Jinkui [ORNL; Robertson, Lee [ORNL; Herwig, Kenneth W [ORNL; Gallmeier, Franz X [ORNL; Riemer, Bernie [ORNL

    2013-01-01

    In this work, we investigate the effect of neutron moderator dimensions on the performance of neutron scattering instruments at the Spallation Neutron Source. In a recent study of the planned second target station at the Spallation Neutron Source (SNS) facility [1,2], we have found that the dimensions of a moderator play a significant role in determining its surface brightness. A smaller moderator may be significantly brighter for a smaller viewing area [4]. One of the immediate implications of this finding is that for modern neutron scattering instrument designs, moderator dimensions and brightness have to be incorporated as an integrated optimization parameter. Here, we establish a strategy of matching neutron scattering instruments with moderators using analytical and Monte Carlo techniques. In order to simplify our treatment, we group the instruments into two broad categories, those with natural collimation and those that use neutron guide systems. We found that the cross-sections of the sample and the neutron guide, respectively, are the deciding factors for choosing the moderator. Beam divergence plays no role as long as it is within the reach of practical constraints. Namely, the required divergence is not too large for the guide or sample to be located close enough to the moderator on an actual spallation source.

  3. Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source

    SciTech Connect (OSTI)

    Andreani, C.; Pietropaolo, A.; Salsano, A.; Gorini, G.; Tardocchi, M.; Paccagnella, A.; Gerardin, S.; Frost, C. D.; Ansell, S.; Platt, S. P.

    2008-03-17

    The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 10{sup 7}. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays.

  4. Spallation production of neutron deficient radioisotopes in North America

    SciTech Connect (OSTI)

    Jamriska, D.J.; Peterson, E.J.; Carty, J.

    1997-12-31

    The US Department of Energy produces a number of neutron deficient radioisotopes by high energy proton induced spallation reactions in accelerators at Los Alamos National Laboratory in New Mexico and Brookhaven National Laboratory in New York. Research isotopes are also recovered from targets irradiated at TRIUMF in British Columbia, Canada. The radioisotopes recovered are distributed for use in nuclear medicine, environmental research, physics research, and industry worldwide. In addition to the main product line of Sr-82 from either Mo or Rb targets, Cu-67 from ZnO targets, and Ge-68 and RbBr targets, these irradiation facilities also produce some unique isotopes in quantities not available from any other source such as Al-26, Mg-28, Si-32, Ti-44, Fe-52, Gd-148, and Hg-194. The authors will describe the accelerator irradiation facilities at the Los Alamos and Brookhaven National Laboratories. The high level radiochemical processing facilities at Los Alamos and brief chemical processes will be described.

  5. Room-temperature LINAC structures for the spallation neutron source

    SciTech Connect (OSTI)

    Billen, J. H.; Young, L. M.; Kurennoy, S.; Crandall, K. R.

    2001-04-01

    Los Alamos National Laboratory is building room-temperature rf accelerating structures for the Spallation Neutron Source (SNS). These structures, for H{sup -} ions, consist of six 402.5-MHz, 2-MW drift-tube linac (DTL) tanks from 2.5 to 87 MeV followed by four 805-MHz, 4-MW coupled-cavity linac (CCL) modules to 186 MeV. The DTL uses permanent magnet quadrupoles inside the drift tubes arranged in a 6{beta}{lambda} FFODDO lattice with every third drift tube available for diagnostics and steering. The CCL uses a 13{beta}{lambda} FODO electromagnetic quadrupole lattice. Diagnostics and magnets occupy the 2.5{beta}{lambda} spaces between 8-cavity segments. This paper discusses design of the rf cavities and low-power modeling work.

  6. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    SciTech Connect (OSTI)

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2014-12-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor, Oak Ridge National Laboratory at reactor coolant temperatures of 50-70C to low displacement damage of 0.025 and 0.3 dpa under the framework of the US-Japan TITAN program (2007-2013). After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 C twice at the ion fluence of 510? m? to reach a total ion fluence of 110? m? in order to investigate the near surface deuterium retention and saturation via nuclear reaction analysis. Final thermal desorption spectroscopy was performed to elucidate irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near surface (<5 m depth) deuterium concentration increased from 0.5 at % D/W in 0.025 dpa samples to 0.8 at. % D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near surface retention via nuclear reaction analysis indicated the deuterium was migrated and trapped in bulk (at least 50 m depth for 0.025 dpa and 35 m depth for 0.025 dpa) at 500 C case even in the relatively low ion fluence of 10? m?.

  7. Evidence of a halo formation mechanism in the Spallation Neutron Source

    Office of Scientific and Technical Information (OSTI)

    linac (Journal Article) | SciTech Connect Journal Article: Evidence of a halo formation mechanism in the Spallation Neutron Source linac Citation Details In-Document Search Title: Evidence of a halo formation mechanism in the Spallation Neutron Source linac Authors: Jeon, Dong-O Publication Date: 2013-04-23 OSTI Identifier: 1091911 Type: Published Article Journal Name: Physical Review Special Topics - Accelerators and Beams Additional Journal Information: Journal Volume: 16; Journal Issue:

  8. 2010 Neutron Review: ORNL Neutron Sciences Progress Report (Technical

    Office of Scientific and Technical Information (OSTI)

    Report) | SciTech Connect Technical Report: 2010 Neutron Review: ORNL Neutron Sciences Progress Report Citation Details In-Document Search Title: 2010 Neutron Review: ORNL Neutron Sciences Progress Report During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown

  9. Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

    SciTech Connect (OSTI)

    Masashi Shimada; M. Hara; T. Otsuka; Y. Oya; Y. Hatano

    2014-05-01

    sample exposed to TPE at 500 C. Tritium Migration Analysis Program (TMAP) analysis reveals that the detrapping energy decreases from 1.8 eV to 1.4 eV, indicating the changes in trapping mechanisms. This paper also summarizes deuterium behavior studies in HFIR neutron-irradiated tungsten under US-Japan TITAN program.

  10. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2014-12-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor, Oak Ridge National Laboratory at reactor coolant temperatures of 50-70°C to low displacement damage of 0.025 and 0.3 dpa under the framework of the US-Japan TITAN program (2007-2013). After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5×10²⁵ m⁻² to reach a total ion fluence of 1×10²⁶ m⁻² in order to investigate the near surface deuterium retention and saturation via nuclear reaction analysis. Finalmore » thermal desorption spectroscopy was performed to elucidate irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near surface (<5 µm depth) deuterium concentration increased from 0.5 at % D/W in 0.025 dpa samples to 0.8 at. % D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near surface retention via nuclear reaction analysis indicated the deuterium was migrated and trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.025 dpa) at 500 °C case even in the relatively low ion fluence of 10²⁶ m⁻².« less

  11. The new Cold Neutron Chopper Spectrometer at the Spallation Neutron Source -- Design and Performance

    SciTech Connect (OSTI)

    Ehlers, Georg; Podlesnyak, Andrey A.; Niedziela, Jennifer L.; Iverson, Erik B.; Sokol, Paul E.

    2011-01-01

    The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

  12. The new cold neutron chopper spectrometer at the Spallation Neutron Source: Design and performance

    SciTech Connect (OSTI)

    Ehlers, G.; Podlesnyak, A. A.; Niedziela, J. L.; Iverson, E. B.; Sokol, P. E.

    2011-08-15

    The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

  13. The COHERENT Experiment at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Elliott, Steven Ray

    2015-09-30

    The COHERENT collaboration's primary objective is to measure coherent elastic neutrino- nucleus scattering (CEvNS) using the unique, high-quality source of tens-of-MeV neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). In spite of its large cross section, the CEvNS process has never been observed, due to tiny energies of the resulting nuclear recoils which are out of reach for standard neutrino detectors. The measurement of CEvNS has now become feasible, thanks to the development of ultra-sensitive technology for rare decay and weakly-interacting massive particle (dark matter) searches. The CEvNS cross section is cleanly predicted in the standard model; hence its measurement provides a standard model test. It is relevant for supernova physics and supernova-neutrino detection, and enables validation of dark-matter detector background and detector-response models. In the long term, precision measurement of CEvNS will address questions of nuclear structure. COHERENT will deploy multiple detector technologies in a phased approach: a 14-kg CsI[Na] scintillating crystal, 15 kg of p-type point-contact germanium detectors, and 100 kg of liquid xenon in a two-phase time projection chamber. Following an extensive background measurement campaign, a location in the SNS basement has proven to be neutron-quiet and suitable for deployment of the COHERENT detector suite. The simultaneous deployment of the three COHERENT detector subsystems will test the N=2 dependence of the cross section and ensure an unambiguous discovery of CEvNS. This document describes concisely the COHERENT physics motivations, sensitivity and plans for measurements at the SNS to be accomplished on a four-year timescale.

  14. Optimizing moderator dimensions for neutron scattering at the spallation neutron source

    SciTech Connect (OSTI)

    Zhao, J. K.; Robertson, J. L.; Herwig, Kenneth W.; Gallmeier, Franz X.; Riemer, Bernard W. [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2013-12-15

    In this work, we investigate the effect of neutron moderator dimensions on the performance of neutron scattering instruments at the Spallation Neutron Source (SNS). In a recent study of the planned second target station at the SNS facility, we have found that the dimensions of a moderator play a significant role in determining its surface brightness. A smaller moderator may be significantly brighter over a smaller viewing area. One of the immediate implications of this finding is that for modern neutron scattering instrument designs, moderator dimensions and brightness have to be incorporated as an integrated optimization parameter. Here, we establish a strategy of matching neutron scattering instruments with moderators using analytical and Monte Carlo techniques. In order to simplify our treatment, we group the instruments into two broad categories: those with natural collimation and those that use neutron guide systems. For instruments using natural collimation, the optimal moderator selection depends on the size of the moderator, the sample, and the moderator brightness. The desired beam divergence only plays a role in determining the distance between sample and moderator. For instruments using neutron optical systems, the smallest moderator available that is larger than the entrance dimension of the closest optical element will perform the best (assuming, as is the case here that smaller moderators are brighter)

  15. EIS-0247: Construction and Operation of the Spallation Neutron Source

    Broader source: Energy.gov [DOE]

    The United States needs a high-flux, short- pulsed neutron source to provide its scientific and industrial research communities with a much more intense source of pulsed neutrons for neutron...

  16. OSTIblog Articles in the Spallation Neutron Source Topic | OSTI, US Dept of

    Office of Scientific and Technical Information (OSTI)

    Energy Office of Scientific and Technical Information Spallation Neutron Source Topic The NXS Class of 2014 by Kathy Chambers 19 Nov, 2014 in Every summer for the past 16 years, the Department of Energy has invited the best and brightest graduates from across the country to attend the National School on Neutron and X-ray Scattering (NXS). This year, 65 graduate students attending North American universities, and studying physics, chemistry, materials science, or related fields, participated

  17. HYSPEC : A CRYSTAL TIME OF FLIGHT HYBRID SPECTROMETER FOR THE SPALLATION NEUTRON SOURCE.

    SciTech Connect (OSTI)

    SHAPIRO,S.M.; ZALIZNYAK,I.A.

    2002-12-30

    This document lays out a proposal by the Instrument Development Team (IDT) composed of scientists from leading Universities and National Laboratories to design and build a conceptually new high-flux inelastic neutron spectrometer at the pulsed Spallation Neutron Source (SNS) at Oak Ridge. This instrument is intended to supply users of the SNS and scientific community, of which the IDT is an integral part, with a platform for ground-breaking investigations of the low-energy atomic-scale dynamical properties of crystalline solids. It is also planned that the proposed instrument will be equipped with a polarization analysis capability, therefore becoming the first polarized beam inelastic spectrometer in the SNS instrument suite, and the first successful polarized beam inelastic instrument at a pulsed spallation source worldwide. The proposed instrument is designed primarily for inelastic and elastic neutron spectroscopy of single crystals. In fact, the most informative neutron scattering studies of the dynamical properties of solids nearly always require single crystal samples, and they are almost invariably flux-limited. In addition, in measurements with polarization analysis the available flux is reduced through selection of the particular neutron polarization, which puts even more stringent limits on the feasibility of a particular experiment. To date, these investigations have mostly been carried out on crystal spectrometers at high-flux reactors, which usually employ focusing Bragg optics to concentrate the neutron beam on a typically small sample. Construction at Oak Ridge of the high-luminosity spallation neutron source, which will provide intense pulsed neutron beams with time-averaged fluxes equal to those at medium-flux reactors, opens entirely new opportunities for single crystal neutron spectroscopy. Drawing upon experience acquired during decades of studies with both crystal and time-of-flight (TOF) spectrometers, the IDT has developed a conceptual

  18. IPNS neutron scattering instrumentation: A -- Existing and planned; B -- Possibilities for IPNS upgrade, a 1-MW spallation source

    SciTech Connect (OSTI)

    Brown, B.; Crawford, K.

    1994-12-01

    The Intense Pulsed Neutron Source (IPNS) is a pulsed spallation neutron source located at Argonne National Laboratory near Chicago, Illinois in the US. This facility is the outgrowth of a long line of pioneering work on pulsed spallation neutron sources begun at Argonne in the early 1970s. IPNS uses protons accelerated in the Rapid Cycling Synchrotron to produce neutrons via the spallation process (effectively a nuclear evaporation in which 10--50 neutrons are released per incident proton) in a heavy-element target. These neutrons are then moderated to produce spectra peaked at thermal or subthermal energies, and directed into beams which serve a variety of instruments. This paper discusses the diffractometers, various spectrometers, and reflectometers in existence and those planned for the upgrade of the IPNS.

  19. Coherent Scattering Investigations at the Spallation Neutron Source: a Snowmass White Paper

    SciTech Connect (OSTI)

    Akimov, D. Moscow Engineering Physics Institute , Russia; Bernstein, A. Lawrence Livermore National Laboratory; BarbeauP.,; Barton, P. J. Lawrence Berkeley National Laboratory; Bolozdynya, A. Moscow Engineering Physics Institute , Russia; Cabrera-Palmer, B. Sandia National Laboratories; Cavanna, F. Yale University; Cianciolo, Vince ORNL; Collar, J. University of Chicago, Enrico Fermi Institute; Cooper, R. J. Indiana University; Dean, D. J. Oak Ridge National Laboratory; Efremenko, Yuri University of Tennessee and Oak Ridge National Laboratory; Etenko, A. Moscow Engineering Physics Institute , Russia; Fields, N. University of Chicago, Enrico Fermi Institute; Foxe, M. Pennsylvania State University, University Park, PA; Figueroa-Feliciano, E. Massachusetts Institute of Technology; Fomin, N. University of Tennessee, Knoxville; Gallmeier, F. Oak Ridge National Laboratory; Garishvili, I. University of Tennessee, Knoxville; Gerling, M. Sandia National Laboratories; Green, M. University of North Carolina, Chapel Hill; Greene, Geoffrey University of Tennessee, Knoxville; Hatzikoutelis, A. University of Tennessee, Knoxville; Henning, Reyco University of North Carolina, Chapel Hill; Hix, R. University of Tennessee and Oak Ridge National Laboratory; Hogan, D. University of California-Berkeley; Hornback, D. University of Tennessee and Oak Ridge National Laboratory; Jovanovic, I. Pennsylvania State University, University Park, PA; Hossbach, T. Pacific Northwest National Laboratory; Iverson, Erik B ORNL; Klein, S. R. Lawrence Berkeley National Laboratory; Khromov, A. Moscow Engineering Physics Institute , Russia; Link, J. Virginia Polytechnic Institute and State University; Louis, W. Los Alamos National Laboratory; Lu, W. Oak Ridge National Laboratory; Mauger, C. Los Alamos National Laboratory; Marleau, P. Sandia National Laboratories; Markoff, D. North Carolina Central University, Durham; Martin, R. D. University of South Dakota; Mueller, Paul Edward ORNL; Newby, J. Oak Ridge National Laboratory; Orrell, John L. Pacific Northwest National Laboratory; O'Shaughnessy, C. University of North Carolina, Chapel Hill; Penttila, Seppo Oak Ridge National Laboratory; Patton, K. North Carolina State University, Raleigh; Poon, A. W. Lawrence Berkeley National Laboratory; Radford, David C ORNL; Reyna, D. Sandia National Laboratories; Ray, H. University of Florida, Gainesville; Scholberg, K. Duke University, North Carolina; Sosnovtsev, V. Moscow Engineering Physics Institute , Russia; Tayloe, R. Indiana University; Vetter, K. Lawrence Berkeley National Laboratory; Virtue, C. Laurentian University, Canada; Wilkerson, J. University of North Carolina, Chapel Hill; Yoo, J. Fermi National Accelerator Laboratory; Yu, Chang-Hong ORNL

    2013-01-01

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS).

  20. Three-dimensional computational fluid dynamics for the Spallation Neutron Source liquid mercury target

    SciTech Connect (OSTI)

    Wendel, M.W.; Siman-Tov, M.

    1998-11-01

    The Spallation Neutron Source (SNS) is a high-power accelerator-based pulsed spallation source being designed by a multilaboratory team led by Oak Ridge National Laboratory (ORNL) to achieve high fluxes of neutrons for scientific experiments. Computational fluid dynamics (CFD) is being used to analyze the SNS design. The liquid-mercury target is subjected to the neutronic (internal) heat generation that results from the proton collisions with the mercury nuclei. The liquid mercury simultaneously serves as the neutronic target medium, transports away the heat generated within itself, and cools the metallic target structure. Recirculation and stagnation zones within the target are of particular concern because of the likelihood that they will result in local hot spots. These zones exist because the most feasible target designs include a complete U-turn flow redirection. Although the primary concern is that the target is adequately cooled, the pressure drop from inlet to outlet must also be considered because pressure drop directly affects structural loading and required pumping power. Based on the current design, a three-dimensional CFD model has been developed that includes the stainless steel target structure, the liquid-mercury target flow, and the liquid-mercury cooling jacket that wraps around the nose of the target.

  1. Neutron Scattering Facilities | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Facilities Scientific User Facilities (SUF) Division SUF Home About User Facilities X-Ray Light Sources Neutron Scattering Facilities Spallation Neutron Source (SNS) High Flux Isotope Reactor (HFIR) Nanoscale Science Research Centers (NSRCs) Projects Accelerator & Detector Research Science Highlights Principal Investigators' Meetings BES Home User Facilities Neutron Scattering Facilities Print Text Size: A A A FeedbackShare Page This activity supports the operation of two neutron scattering

  2. A comparison of four direct geometry time-of-flight spectrometers at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Stone, Matthew B; Niedziela, Jennifer L; Abernathy, Douglas L; Debeer-Schmitt, Lisa M; Garlea, Vasile O; Granroth, Garrett E; Graves-Brook, Melissa K; Ehlers, Georg; Kolesnikov, Alexander I; Podlesnyak, Andrey A; Winn, Barry L

    2014-04-01

    The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave vector and energy transfer space with varying degrees of neutron flux and resolution. The regions of reciprocal and energy space available to measure at these instruments is not exclusive and overlaps significantly. We present a direct comparison of the capabilities of this instrumentation, conducted by data mining the instrument usage histories, and specific scanning regimes. In addition, one of the common science missions for these instruments is the study of magnetic excitations in condensed matter systems. We have measured the powder averaged spin wave spectra in one particular sample using each of these instruments, and use these data in our comparisons.

  3. A comparison of four direct geometry time-of-flight spectrometers at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Stone, M. B.; Abernathy, D. L.; Ehlers, G.; Garlea, O.; Podlesnyak, A.; Winn, B.; Niedziela, J. L.; DeBeer-Schmitt, L.; Graves-Brook, M.; Granroth, G. E.; Kolesnikov, A. I.

    2014-04-15

    The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave-vector and energy transfer space with varying degrees of neutron flux and resolution. The regions of reciprocal and energy space available to measure at these instruments are not exclusive and overlap significantly. We present a direct comparison of the capabilities of this instrumentation, conducted by data mining the instrument usage histories, and specific scanning regimes. In addition, one of the common science missions for these instruments is the study of magnetic excitations in condensed matter systems. We have measured the powder averaged spin wave spectra in one particular sample using each of these instruments, and use these data in our comparisons.

  4. Spallation Neutrons and Pressure ?? SNAP ?? DE-FG02-03ER46085 CLOSE-OUT MAY 2009

    SciTech Connect (OSTI)

    John B Parise

    2009-05-22

    The purpose of the grant was to build a community of scientist and to draw upon their expertise to design and build the world's first dedicated high pressure beamline at a spallation source - the so called Spallation Neutron And Pressure (SNAP) beamline at the Spallation Neutron Source (SNS) at OAk Ridge NAtional LAboratory. . Key to this endeavor was an annual meeting attended by the instrument design team and the executive committee. The discussions at those meeting set an ambitious agenda for beamline design and construction and highlighted key science areas of interest for the community. This report documents in 4 appendices the deliberations at the annual SNAP meetings and the evolution of the beamline optics from concept to construction. The appendices also contain key science opportunities for extreme conditions research.

  5. Thermal-hydraulic simulation of mercury target concepts for a pulsed spallation neutron source

    SciTech Connect (OSTI)

    Siman-Tov, M.; Wendel, M.; Haines, J.

    1996-06-01

    The Oak Ridge Spallation Neutron Source (ORSNS) is a high-power, accelerator-based pulsed spallation neutron source being designed by a multi-laboratory team led by Oak Ridge National Laboratory to achieve very high fluxes of neutrons for scientific experiments. The ORSNS is projected to have a 1 MW proton beam upgradable to 5 MW. About 60% of the beam power (1-5 MW, 17-83 kJ/pulse in 0.5 microsec at 60 cps) is deposited in the liquid metal (mercury) target having the dimensions of 65x30x10 cm (about 19.5 liter). Peak steady state power density is about 150 and 785 MW/m{sup 3} for 1 MW and 5 MW beam respectively, whereas peak pulsed power density is as high as 5.2 and 26.1 GW/m{sup 3}, respectively. The peak pulse temperature rise rate is 14 million C/s (for 5 MW beam) whereas the total pulse temperature rise is only 7 C. In addition to thermal shock and materials compatibility, key feasibility issues for the target are related to its thermal-hydraulic performance. This includes proper flow distribution, flow reversals, possible {open_quotes}hot spots{close_quotes} and the challenge of mitigating the effects of thermal shock through possible injection of helium bubbles throughout the mercury volume or other concepts. The general computational fluid dynamics (CFD) code CFDS-FLOW3D was used to simulate the thermal and flow distribution in three preliminary concepts of the mercury target. Very initial CFD simulation of He bubbles injection demonstrates some potential for simulating behavior of He bubbles in flowing mercury. Much study and development will be required to be able to `predict`, even in a crude way, such a complex phenomena. Future direction in both design and R&D is outlined.

  6. EXPERIENCE WITH COLLABORATIVE DEVELOPMENT FOR THE SPALLATION NEUTRON SOURCE FROM A PARTNER LAB PERSPECTIVE.

    SciTech Connect (OSTI)

    HOFF, L.T.

    2005-10-10

    Collaborative development and operation of large physics experiments is fairly common. Less common is the collaborative development or operation of accelerators. A current example of the latter is the Spallation Neutron Source (SNS). The SNS project was conceived as a collaborative effort between six DOE facilities. In the SNS case, the control system was also developed collaboratively. The SNS project has now moved beyond the collaborative development phase and into the phase where Oak Ridge National Lab (ORNL) is integrating contributions from collaborating ''partner labs'' and is beginning accelerator operations. In this paper, the author reflects on the benefits and drawbacks of the collaborative development of an accelerator control system as implemented for the SNS project from the perspective of a partner lab.

  7. Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation

    SciTech Connect (OSTI)

    Han, B. X.; Welton, R. F.; Murray, S. N. Jr.; Pennisi, T. R.; Santana, M.; Stockli, M. P.; Kalvas, T.; Tarvainen, O.

    2012-02-15

    The H{sup -} injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with {approx}38 mA beam current in the linac at 60 Hz with a pulse length of up to {approx}1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

  8. Design of an Aluminum Proton Beam Window for the Spallation Neutron Source

    SciTech Connect (OSTI)

    Janney, Jim G; McClintock, David A

    2012-01-01

    An aluminum proton beam window design is being considered at the Spallation Neutron Source primarily to increase the lifetime of the window, with secondary advantages of higher beam transport efficiency and lower activation. The window separates the core vessel, the location of the mercury target, from the vacuum of the accelerator, while withstanding the pass through of a proton beam of up to 2 MW with 1.0 GeV proton energy. The current aluminum alloy being investigated for the window material is 6061-T651 due to its combination of high strength, high thermal conductivity, and good resistance to aqueous corrosion, as well as demonstrated dependability in previous high-radiation environments. The window design will feature a thin plate with closely spaced cross drilled cooling holes. An analytical approach was used to optimize the dimensions of the window before finite element analysis was used to simulate temperature profiles and stress fields resulting from thermal and static pressure loading. The resulting maximum temperature of 60 C and Von Mises stress of 71 MPa are very low compared to allowables for Al 6061-T651. A significant challenge in designing an aluminum proton beam window for SNS is integrating the window with the current 316L SS shield blocks. Explosion bonding was chosen as a joining technique because of the large bonding area required. A test program has commenced to prove explosion bonding can produce a robust vacuum joint. Pending successful explosion bond testing, the aluminum proton beam window design will be proven acceptable for service in the Spallation Neutron Source.

  9. Department of Energy review of the National Spallation Neutron Source Project

    SciTech Connect (OSTI)

    1997-06-01

    A Department of Energy (DOE) review of the Conceptual Design Report (CDR) for the National Spallation Neutron Source (NSNS) was conducted. The NSNS will be a new high-power spallation neutron source; initially, it will operate at 1 megawatt (MW), but is designed to be upgradeable to significantly higher power, at lower cost, when accelerator and target technologies are developed for higher power. The 53-member Review Committee examined the projected cost, schedule, technical scope, and management structure described in the CDR. For each of the major components of the NSNS, the Committee determined that the project team had produced credible designs that can be expected to work well. What remains to be done is to integrate the design of these components. With the exception of the liquid mercury target, the NSNS Project will rely heavily on proven technologies and, thus, will face a relatively low risk to successful project completion. The Total Project Cost (TPC) presented to the Committee in the CDR was $1.266 billion in as-spent dollars. In general, the Committee felt that the laboratory consortium had presented a credible estimate for each of the major components but that value engineering might produce some savings. The construction schedule presented to the Committee covered six years beginning in FY 1999. The Committee questioned whether all parts of the project could be completed according to this schedule. In particular, the linac and the conventional facilities appeared to have overly optimistic schedules. The NSNS project team was encouraged to reexamine these activities and to consider a more conservative seven-year schedule. Another concern of the Committee was the management structure. In summary, the Committee felt that this Conceptual Design Report was a very credible proposal, and that there is a high probability for successful completion of this major project within the proposed budget, although the six-year proposed schedule may be optimistic.

  10. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mauro, N. A.; Vogt, A. J.; Derendorf, K. S.; Johnson, M. L.; Rustan, G. E.; Quirinale, D. G.; Kreyssig, A.; Lokshin, K. A.; Neuefeind, J. C.; An, Ke; et al

    2016-01-01

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. But, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elasticmore » and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. Furthermore, to demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample ( 100 mg).« less

  11. Accelerating Data Acquisition, Reduction, and Analysis at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Campbell, Stuart I; Kohl, James Arthur; Granroth, Garrett E; Miller, Ross G; Doucet, Mathieu; Stansberry, Dale V; Proffen, Thomas E; Taylor, Russell J; Dillow, David

    2014-01-01

    ORNL operates the world's brightest neutron source, the Spallation Neutron Source (SNS). Funded by the US DOE Office of Basic Energy Science, this national user facility hosts hundreds of scientists from around the world, providing a platform to enable break-through research in materials science, sustainable energy, and basic science. While the SNS provides scientists with advanced experimental instruments, the deluge of data generated from these instruments represents both a big data challenge and a big data opportunity. For example, instruments at the SNS can now generate multiple millions of neutron events per second providing unprecedented experiment fidelity but leaving the user with a dataset that cannot be processed and analyzed in a timely fashion using legacy techniques. To address this big data challenge, ORNL has developed a near real-time streaming data reduction and analysis infrastructure. The Accelerating Data Acquisition, Reduction, and Analysis (ADARA) system provides a live streaming data infrastructure based on a high-performance publish subscribe system, in situ data reduction, visualization, and analysis tools, and integration with a high-performance computing and data storage infrastructure. ADARA allows users of the SNS instruments to analyze their experiment as it is run and make changes to the experiment in real-time and visualize the results of these changes. In this paper we describe ADARA, provide a high-level architectural overview of the system, and present a set of use-cases and real-world demonstrations of the technology.

  12. Design progress of cryogenic hydrogen system for China Spallation Neutron Source

    SciTech Connect (OSTI)

    Wang, G. P.; Zhang, Y.; Xiao, J.; He, C. C.; Ding, M. Y.; Wang, Y. Q.; Li, N.; He, K.

    2014-01-29

    China Spallation Neutron Source (CSNS) is a large proton accelerator research facility with 100 kW beam power. Construction started in October 2011 and is expected to last 6.5 years. The cryogenic hydrogen circulation is cooled by a helium refrigerator with cooling capacity of 2200 W at 20 K and provides supercritical hydrogen to neutron moderating system. Important progresses of CSNS cryogenic system were concluded as follows. Firstly, process design of cryogenic system has been completed including helium refrigerator, hydrogen loop, gas distribution, and safety interlock. Secondly, an accumulator prototype was designed to mitigate pressure fluctuation caused by dynamic heat load from neutron moderation. Performance test of the accumulator has been carried out at room and liquid nitrogen temperature. Results show the accumulator with welding bellows regulates hydrogen pressure well. Parameters of key equipment have been identified. The contract for the helium refrigerator has been signed. Mechanical design of the hydrogen cold box has been completed, and the hydrogen pump, ortho-para hydrogen convertor, helium-hydrogen heat exchanger, hydrogen heater, and cryogenic valves are in procurement. Finally, Hydrogen safety interlock has been finished as well, including the logic of gas distribution, vacuum, hydrogen leakage and ventilation. Generally, design and construction of CSNS cryogenic system is conducted as expected.

  13. Characterization of an explosively bonded aluminum proton beam window for the Spallation Neutron Source

    SciTech Connect (OSTI)

    McClintock, David A; Janney, Jim G; Parish, Chad M

    2014-01-01

    An effort is underway at the Spallation Neutron Source (SNS) to change the design of the 1st Generation high-nickel alloy proton beam window (PBW) to one that utilizes aluminum for the window material. One of the key challenges to implementation of an aluminum PBW at the SNS was selection of an appropriate joining method to bond an aluminum window to the stainless steel bulk shielding of the PBW assembly. An explosively formed bond was selected as the most promising joining method for the aluminum PBW design. A testing campaign was conducted to evaluate the strength and efficacy of explosively formed bonds that were produced using two different interlayer materials: niobium and titanium. The characterization methods reported here include tensile testing, thermal-shock leak testing, optical microscopy, and advanced scanning electron microscopy. All tensile specimens examined failed in the aluminum interlayer and measured tensile strengths were all slightly greater than the native properties of the aluminum interlayer, while elongation values were all slightly lower. A leak developed in the test vessel with a niobium interlayer joint after repeated thermal-shock cycles, and was attributed to an extensive crack network that formed in a layer of niobium-rich intermetallics located on the bond interfaces of the niobium interlayer; the test vessel with a titanium interlayer did not develop a leak under the conditions tested. Due to the experience gained from these characterizations, the explosively formed bond with a titanium interlayer was selected for the aluminum PBW design at the SNS.

  14. High-power linac for a US spallation-neutron source

    SciTech Connect (OSTI)

    Wangler, T.P.; Billen, J.; Jason, A. Krawczyk, F.; Nath, S.; Shafer, R.; Staples, J.; Takeda, H.; Tallerico, P.

    1996-09-01

    We present status of high-power linac design studies for a proposed National Spallation Neutron Source (NSNS), based on a linac/accumulator-ring accelerator system. Overall project is a collaboration involving 5 national laboratories. ORNL will be responsible for the target, facilities, and conceptual design; BNL will be responsible for the ring; LBNL will be responsible for the injector, including the RFQ and a low-energy chopper in front of the RFQ; LANL will be responsible for the main linac; and ANL will be responsible for the instrumentation. The facility will be built at Oak Ridge. In the first phase, the dual-frequency linac with 402.5 and 805 MHz frequencies must deliver to the accumulator ring an H{sup -} beam near 1 GeV, with about 1 ms pulse length, a repetition rate 60 Hz, and average beam power {ge} 1 MW. The linac can be upgraded by a factor of 4 in beam power by increasing the dc injector current, and by funneling the beams from two 402.5 MHz low-energy linacs into the 805-MHz high-energy linac. Requirements for low beam loss in both linac and ring have important implications for linac design, including the requirement to provide efficient beam chopping to provide low-loss extraction for the ring. Linac design options and initial parameters are presented together with initial beam-dynamics simulation results.

  15. Separation of beam and electrons in the spallation neutron source H{sup -} ion source

    SciTech Connect (OSTI)

    Whealton, J.H.; Raridon, R.J.; Leung, K.N.

    1997-12-01

    The Spallation Neutron Source (SNS) requires an ion source producing an H{sup {minus}} beam with a peak current of 35mA at a 6.2 percent duty factor. For the design of this ion source, extracted electrons must be transported and dumped without adversely affecting the H{sup {minus}} beam optics. Two issues are considered: (1) electron containment transport and controlled removal; and (2) first-order H{sup {minus}} beam steering. For electron containment, various magnetic, geometric and electrode biasing configurations are analyzed. A kinetic description for the negative ions and electrons is employed with self-consistent fields obtained from a steady-state solution to Poisson`s equation. Guiding center electron trajectories are used when the gyroradius is sufficiently small. The magnetic fields used to control the transport of the electrons and the asymmetric sheath produced by the gyrating electrons steer the ion beam. Scenarios for correcting this steering by split acceleration and focusing electrodes will be considered in some detail.

  16. Initial tests of the Spallation Neutron Source H{sup -} ion source with an external antenna

    SciTech Connect (OSTI)

    Welton, R.F.; Stockli, M.P.; Murray, S.N.; Kang, Y.; Peters, J.

    2006-03-15

    The ion source for the Spallation Neutron Source (SNS) is a radio-frequency (rf) multicusp source designed to deliver H{sup -} beam pulses of 40 mA to the SNS accelerator with a normalized root-mean-square emittance of less than 0.2{pi} mm mrad, with a pulse length of 1 ms and a repetition rate of 60 Hz. In order to achieve this performance the source must operate with both high-pulse rf power, {approx}50 kW, and high average rf power, {approx}3.5 kW, over a continuous operational period of 3 weeks. During operation at these power levels the plasma-immersed, porcelain-coated rf antenna is susceptible to damage, limiting source lifetime. We are therefore developing an ion source where the plasma is separated from the Cu antenna by an Al{sub 2}O{sub 3} discharge chamber. This article describes the ion source, presents initial beam extraction measurements, and details our ongoing effort to develop this concept into a suitable ion source for the SNS.

  17. Advances in the performance and understanding of the Spallation Neutron Source ion source

    SciTech Connect (OSTI)

    Welton, R.F.; Stockli, M.P.; Murray, S.N.

    2006-03-15

    The ion source developed for the Spallation Neutron Source (SNS) is a radio-frequency, multicusp source designed to produce {approx}40 mA of H{sup -} with a normalized rms emittance of less than 0.2 {pi} mm mrad. To date, the source has been utilized in the commissioning of the SNS accelerator and has already demonstrated stable, satisfactory operation at beam currents of 10-40 mA with duty factors of {approx}0.1% for operational periods of several weeks. Ultimately the SNS facility will require beam duty factors of 6% (1 ms pulse length, 60 Hz repetition rate). To ascertain the capability of the source to deliver beams at this duty factor over sustained periods, ongoing experiments are being performed in which the ion source is continuously operated on a dedicated test stand. The results of these tests are reported as well as a theory of the Cs release and transport processes that was derived from these data. The theory was then employed to develop a more effective source-conditioning procedure and a direct-transfer Cs collar, which led to a considerable improvement in source performance.

  18. Thermohydraulic behavior of the liquid metal target of a spallation neutron source

    SciTech Connect (OSTI)

    Takeda, Y.

    1996-06-01

    The author presents work done on three main problems. (1) Natural circulation in double coaxial cylindircal container: The thermohydraulic behaviour of the liquid metal target of the spallation neutron source at PSI has been investigated. The configuration is a natural-circulation loop in a concentric double-tube-type container. The results show that the natural-circulation loop concept is valid for the design phase of the target construction, and the current specified design criteria will be fulfilled with the proposed parameter values. (2) Flow around the window: Water experiments were performed for geometry optimisation of the window shape of the SINQ container for avoiding generating recirculation zones at peripheral area and the optimal cooling of the central part of the beam entrance window. Flow visualisation technique was mainly used for various window shapes, gap distance between the window and the guide tube edge. (3) Flow in window cooling channels: Flows in narrow gaps of cooling channels of two different types of windows were studied by flow visualisation techniques. One type is a slightly curved round cooling channel and the other is hemispherical shape, both of which have only 2 mm gap distance and the water inlet is located on one side and flows out from the opposite side. In both cases, the central part of the flow area has lower velocity than peripheral area.

  19. Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source

    SciTech Connect (OSTI)

    Lacy, Jeffrey L

    2009-05-22

    Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically

  20. Performance of the Los Alamos National Laboratory spallation-driven solid-deuterium ultra-cold neutron source

    SciTech Connect (OSTI)

    Saunders, A.; Makela, M.; Bagdasarova, Y.; Boissevain, J.; Bowles, T. J.; Currie, S. A.; Hill, R. E.; Hogan, G.; Morris, C. L.; Mortensen, R. N.; Ramsey, J.; Seestrom, S. J.; Sondheim, W. E.; Teasdale, W.; Wang, Z. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Back, H. O.; Broussard, L. J.; Hoagland, J.; Holley, A. T.; Pattie, R. W. Jr. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); and others

    2013-01-15

    In this paper, we describe the performance of the Los Alamos spallation-driven solid-deuterium ultra-cold neutron (UCN) source. Measurements of the cold neutron flux, the very low energy neutron production rate, and the UCN rates and density at the exit from the biological shield are presented and compared to Monte Carlo predictions. The cold neutron rates compare well with predictions from the Monte Carlo code MCNPX and the UCN rates agree with our custom UCN Monte Carlo code. The source is shown to perform as modeled. The maximum delivered UCN density at the exit from the biological shield is 52(9) UCN/cc with a solid deuterium volume of {approx}1500 cm{sup 3}.

  1. H{sup -} radio frequency source development at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Welton, R. F.; Gawne, K. R.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Roseberry, R. T.; Santana, M.; Stockli, M. P.; Dudnikov, V. G.; Turvey, M. W.

    2012-02-15

    The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. H{sup -} beam pulses ({approx}1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, {approx}60 kW) of a copper antenna that has been encased with a thickness of {approx}0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of {approx}99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of {approx}75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to {approx}100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.

  2. Nanodiamond Foils for H- Stripping to Support the Spallation Neutron Source (SNS) and Related Applications

    SciTech Connect (OSTI)

    Vispute, R D; Ermer, Henry K; Sinsky, Phillip; Seiser, Andrew; Shaw, Robert W; Wilson, Leslie L; Harris, Gary; Piazza, Fabrice

    2013-01-01

    Thin diamond foils are needed in many particle accelerator experiments regarding nuclear and atomic physics, as well as in some interdisciplinary research. Particularly, nanodiamond texture is attractive for this purpose as it possesses a unique combination of diamond properties such as high thermal conductivity, mechanical strength and high radiation hardness; therefore, it is a potential material for energetic ion beam stripper foils. At the ORNL Spallation Neutron Source (SNS), the installed set of foils must be able to survive a nominal five-month operation period, without the need for unscheduled costly shutdowns and repairs. Thus, a single nanodiamond foil about the size of a postage stamp is critical to the entire operation of SNS and similar sources in U.S. laboratories and around the world. We are investigating nanocrystalline, polycrystalline and their admixture films fabricated using a hot filament chemical vapor deposition (HFCVD) system for H- stripping to support the SNS at Oak Ridge National Laboratory. Here we discuss optimization of process variables such as substrate temperature, process gas ratio of H2/Ar/CH4, substrate to filament distance, filament temperature, carburization conditions, and filament geometry to achieve high purity diamond foils on patterned silicon substrates with manageable intrinsic and thermal stresses so that they can be released as free standing foils without curling. An in situ laser reflectance interferometry tool (LRI) is used for monitoring the growth characteristics of the diamond thin film materials. The optimization process has yielded free standing foils with no pinholes. The sp3/sp2 bonds are controlled to optimize electrical resistivity to reduce the possibility of surface charging of the foils. The integrated LRI and HFCVD process provides real time information on the growth of films and can quickly illustrate growth features and control over film thickness. The results are discussed in the light of development

  3. Advancing Materials Science using Neutrons at Oak Ridge National Laboratory

    ScienceCinema (OSTI)

    Carpenter, John

    2014-06-03

    Jack Carpenter, pioneer of accelerator-based pulsed spallation neutron sources, talks about neutron science at Oak Ridge National Laboratory (ORNL) and a need for a second target station at the Spallation Neutron Source (SNS). ORNL is the Department of Energy's largest multiprogram science and energy laboratory, and is home to two scientific user facilities serving the neutron science research community: the High Flux Isotope Reactor (HFIR) and SNS. HFIR and SNS provide researchers with unmatched capabilities for understanding the structure and properties of materials, macromolecular and biological systems, and the fundamental physics of the neutron. Neutrons provide a window through which to view materials at a microscopic level that allow researchers to develop better materials and better products. Neutrons enable us to understand materials we use in everyday life. Carpenter explains the need for another station to produce long wavelength neutrons, or cold neutrons, to answer questions that are addressed only with cold neutrons. The second target station is optimized for that purpose. Modern technology depends more and more upon intimate atomic knowledge of materials, and neutrons are an ideal probe.

  4. Model-Based Least Squares Reconstruction of Coded Source Neutron Radiographs: Integrating the ORNL HFIR CG1D Source Model

    SciTech Connect (OSTI)

    Santos-Villalobos, Hector J; Gregor, Jens; Bingham, Philip R

    2014-01-01

    At the present, neutron sources cannot be fabricated small and powerful enough in order to achieve high resolution radiography while maintaining an adequate flux. One solution is to employ computational imaging techniques such as a Magnified Coded Source Imaging (CSI) system. A coded-mask is placed between the neutron source and the object. The system resolution is increased by reducing the size of the mask holes and the flux is increased by increasing the size of the coded-mask and/or the number of holes. One limitation of such system is that the resolution of current state-of-the-art scintillator-based detectors caps around 50um. To overcome this challenge, the coded-mask and object are magnified by making the distance from the coded-mask to the object much smaller than the distance from object to detector. In previous work, we have shown via synthetic experiments that our least squares method outperforms other methods in image quality and reconstruction precision because of the modeling of the CSI system components. However, the validation experiments were limited to simplistic neutron sources. In this work, we aim to model the flux distribution of a real neutron source and incorporate such a model in our least squares computational system. We provide a full description of the methodology used to characterize the neutron source and validate the method with synthetic experiments.

  5. Instrument performance study on the short and long pulse options of the second Spallation Neutron Source target station

    SciTech Connect (OSTI)

    Zhao, J. K.; Herwig, Kenneth W.; Robertson, J. L.; Gallmeier, Franz X.; Riemer, Bernard W.

    2013-10-15

    The Spallation Neutron Source (SNS) facility at the Oak Ridge National Laboratory is designed with an upgrade option for a future low repetition rate, long wavelength second target station. This second target station is intended to complement the scientific capabilities of the 1.4 MW, 60 Hz high power first target station. Two upgrade possibilities have been considered, the short and the long pulse options. In the short pulse mode, proton extraction occurs after the pulse compression in the accumulator ring. The proton pulse structure is thus the same as that for the first target station with a pulse width of ∼0.7 μs. In the long pulse mode, protons are extracted as they are produced by the linac, with no compression in the accumulator ring. The time width of the uncompressed proton pulse is ∼1 ms. This difference in proton pulse structure means that neutron pulses will also be different. Neutron scattering instruments thus have to be designed and optimized very differently for these two source options which will directly impact the overall scientific capabilities of the SNS facility. In order to assess the merits of the short and long pulse target stations, we investigated a representative suit of neutron scattering instruments and evaluated their performance under each option. Our results indicate that the short pulse option will offer significantly better performance for the instruments and is the preferred choice for the SNS facility.

  6. Conceptual Design for Replacement of the DTL and CCL with Superconducting RF Cavities in the Spallation Neutron Source Linac

    SciTech Connect (OSTI)

    Champion, Mark S; Doleans, Marc; Kim, Sang-Ho

    2013-01-01

    The Spallation Neutron Source Linac utilizes normal conducting RF cavities in the low energy section from 2.5 MeV to 186 MeV. Six Drift Tube Linac (DTL) structures accelerate the beam to 87 MeV, and four Coupled Cavity Linac (CCL) structures provide further acceleration to 186 MeV. The remainder of the Linac is comprised of 81 superconducting cavities packaged in 23 cryomodules to provide final beam energy of approximately 1 GeV. The superconducting Linac has proven to be substantially more reliable than the normal conducting Linac despite the greater number of stations and the complexity associated with the cryogenic plant and distribution. A conceptual design has been initiated on a replacement of the DTL and CCL with superconducting RF cavities. The motivation, constraints, and conceptual design are presented.

  7. Development of the radio frequency driven H{sup {minus}} ion source for the National Spallation Neutron Source

    SciTech Connect (OSTI)

    Leitner, M.A.; Gough, R.A.; Leung, K.N.; Rickard, M.L.; Scott, P.K.; Wengrow, A.B.; Williams, M.D.; Wutte, D.C.

    1998-02-01

    The ion source for the 1 MW National Spallation Neutron Source (NSNS) is required to provide 35mA of H{sup {minus}} beam current (1 ms pulses at 60 Hz) at 65 keV with a normalized root-mean-square emittance of {lt}0.2 pimmmrad. The same ion source should be able to produce 70 mA of H{sup {minus}}at 6{percent} duty factor when the NSNS is upgraded to 2 MW of power. For this application, a radio-frequency driven, magnetically filtered multicusp source is being developed at Lawrence Berkeley National Laboratory. The design of this R and D ion source, which is equipped with a cesium dispenser-collar, a fast ion beam prechopper (rise times {lt}100 ns) and a strong permanent-magnet insert for electron deflection, will be presented.{copyright} {ital 1998 American Institute of Physics.}

  8. Calculation Package: Derivation of Facility-Specific Derived Air Concentration (DAC) Values in Support of Spallation Neutron Source Operations

    SciTech Connect (OSTI)

    McLaughlin, David A

    2009-12-01

    Derived air concentration (DAC) values for 175 radionuclides* produced at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS), but not listed in Appendix A of 10 CFR 835 (01/01/2009 version), are presented. The proposed DAC values, ranging between 1 E-07 {micro}Ci/mL and 2 E-03 {micro}Ci/mL, were calculated in accordance with the recommendations of the International Commission on Radiological Protection (ICRP), and are intended to support an exemption request seeking regulatory relief from the 10 CFR 835, Appendix A, requirement to apply restrictive DACs of 2E-13 {micro}Ci/mL and 4E-11 {micro}Ci/mL and for non-listed alpha and non-alpha-emitting radionuclides, respectively.

  9. Simulation of H{sup -} ion source extraction systems for the Spallation Neutron Source with Ion Beam Simulator

    SciTech Connect (OSTI)

    Kalvas, T.; Tarvainen, O.; Welton, R. F.; Han, B. X.; Stockli, M. P.

    2012-02-15

    A three-dimensional ion optical code IBSimu, which is being developed at University of Jyvaeskylae, features positive and negative ion plasma extraction models and self-consistent space charge calculation. The code has been utilized for modeling the existing extraction system of the H{sup -} ion source of the Spallation Neutron Source. Simulation results are in good agreement with experimental data. A high-current extraction system with downstream electron dumping at intermediate energy has been designed. According to the simulations it provides lower emittance compared to the baseline system at H{sup -} currents exceeding 40 mA. A magnetic low energy beam transport section consisting of two solenoids has been designed to transport the beam from the alternative electrostatic extraction systems to the radio frequency quadrupole.

  10. Spin exchange optical pumping based polarized {sup 3}He filling station for the Hybrid Spectrometer at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Jiang, C. Y.; Tong, X.; Brown, D. R.; Culbertson, H.; Kadron, B.; Robertson, J. L.; Graves-Brook, M. K.; Hagen, M. E.; Lee, W. T.; Winn, B.

    2013-06-15

    The Hybrid Spectrometer (HYSPEC) is a new direct geometry spectrometer at the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is equipped with polarization analysis capability with 60 Degree-Sign horizontal and 15 Degree-Sign vertical detector coverages. In order to provide wide angle polarization analysis for this instrument, we have designed and built a novel polarized {sup 3}He filling station based on the spin exchange optical pumping method. It is designed to supply polarized {sup 3}He gas to HYSPEC as a neutron polarization analyzer. In addition, the station can optimize the {sup 3}He pressure with respect to the scattered neutron energies. The depolarized {sup 3}He gas in the analyzer can be transferred back to the station to be repolarized. We have constructed the prototype filling station. Preliminary tests have been carried out demonstrating the feasibility of the filling station. Here, we report on the design, construction, and the preliminary results of the prototype filling station.

  11. PERFORMING DIAGNOSTICS ON THE SPALLATION NEUTRON SOURCE VISION BEAM LINE TO ELIMINATE HIGH VIBRATION LEVELS AND PROVIDE A SUSTAINABLE OPERATION

    SciTech Connect (OSTI)

    Van Hoy, Blake W

    2014-01-01

    The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) provides variable energy neutrons for a variety of experiments. The neutrons proceed down beam lines to the experiment hall, which houses a variety of experiments and test articles. Each beam line has one or more neutron choppers which filter the neutron beam based on the neutron energy by using a rotating neutron absorbing material passing through the neutron beam. Excessive vibration of the Vision beam line, believed to be caused by the T0 chopper, prevented the Vision beam line from operating at full capacity. This problem had been addressed several times by rebalancing/reworking the T0 beam chopper but the problem stubbornly persisted. To determine the cause of the high vibration, dynamic testing was performed. Twenty-seven accelerometer and motor current channels of data were collected during drive up, drive down, coast down, and steady-state conditions; resonance testing and motor current signature analysis were also performed. The data was analyzed for traditional mechanical/machinery issues such as misalignment and imbalance using time series analysis, frequency domain analysis, and operating deflection shape analysis. The analysis showed that the chopper base plate was experiencing an amplified response to the excitation provided by the T0 beam chopper. The amplified response was diagnosed to be caused by higher than expected base plate flexibility, possibly due to improper grouting or loose floor anchors. Based on this diagnosis, a decision was made to dismantle the beam line chopper and remount the base plate. Neutron activation of the beam line components make modifications to the beam line especially expensive and time consuming due to the radiation handling requirements, so this decision had significant financial and schedule implications. It was found that the base plate was indeed loose because of improper grouting during its initial installation. The base plate was

  12. Neutronics analyses in support of rotating target developments at SNS

    SciTech Connect (OSTI)

    Gallmeier, Franz X.

    2010-03-08

    A second target station (STS) for Spallation Neutron Souce (SNS) very likely being operated in long-pulse mode is in the early design phase, will complement the ORNL neutron sources, which presently consist of a short-pulse spallation source and the HFIR research reactor. As an alternative to the stationary liquid metal target, a rotating target is being considered. Neutronics studies in support of a 3MW power 20 Hz repetition rate rotating target feasibility study funded through the laboratory LDRD program, was extended towards a 1.5 MW STS design. The scope of work included in-operation heat deposition rates in target structures for thermal and structural analyses, target radionuclide inventory for decay heat and safety analyses, lifetime estimations due to radiation-driven material damage of target and moderator components, moderator neutron performance and moderator cryogenic heatloads.

  13. HFIR spent fuel management alternatives

    SciTech Connect (OSTI)

    Begovich, J.M.; Green, V.M.; Shappert, L.B.; Lotts, A.L.

    1992-10-15

    The High Flux Isotope Reactor (HFIR) at Martin Marietta Energy Systems' Oak Ridge National Laboratory (ORNL) has been unable to ship its spent fuel to Savannah River Site (SRS) for reprocessing since 1985. The HFIR storage pools are expected to fill up in the February 1994 to February 1995 time frame. If a management altemative to existing HFIR pool storage is not identified and implemented before the HFIR pools are full, the HFIR will be forced to shut down. This study investigated several alternatives for managing the HFIR spent fuel, attempting to identify options that could be implemented before the HFIR pools are full. The options investigated were: installing a dedicated dry cask storage facility at ORNL, increasing HFIR pool storage capacity by clearing the HFIR pools of debris and either close-packing or stacking the spent fuel elements, storing the spent fuel at another ORNL pool, storing the spent fuel in one or more hot cells at ORNL, and shipping the spent fuel offsite for reprocessing or storage elsewhere.

  14. HFIR spent fuel management alternatives

    SciTech Connect (OSTI)

    Begovich, J.M.; Green, V.M.; Shappert, L.B.; Lotts, A.L.

    1992-10-15

    The High Flux Isotope Reactor (HFIR) at Martin Marietta Energy Systems` Oak Ridge National Laboratory (ORNL) has been unable to ship its spent fuel to Savannah River Site (SRS) for reprocessing since 1985. The HFIR storage pools are expected to fill up in the February 1994 to February 1995 time frame. If a management altemative to existing HFIR pool storage is not identified and implemented before the HFIR pools are full, the HFIR will be forced to shut down. This study investigated several alternatives for managing the HFIR spent fuel, attempting to identify options that could be implemented before the HFIR pools are full. The options investigated were: installing a dedicated dry cask storage facility at ORNL, increasing HFIR pool storage capacity by clearing the HFIR pools of debris and either close-packing or stacking the spent fuel elements, storing the spent fuel at another ORNL pool, storing the spent fuel in one or more hot cells at ORNL, and shipping the spent fuel offsite for reprocessing or storage elsewhere.

  15. Operational characteristics of the J-PARC cryogenic hydrogen system for a spallation neutron source

    SciTech Connect (OSTI)

    Tatsumoto, Hideki; Ohtsu, Kiichi; Aso, Tomokazu; Kawakami, Yoshihiko; Teshigawara, Makoto

    2014-01-29

    The J-PARC cryogenic hydrogen system provides supercritical hydrogen with the para-hydrogen concentration of more than 99 % and the temperature of less than 20 K to three moderators so as to provide cold pulsed neutron beams of a higher neutronic performance. Furthermore, the temperature fluctuation of the feed hydrogen stream is required to be within 0.25 K. A stable 300-kW proton beam operation has been carried out since November 2012. The para-hydrogen concentrations were measured during the cool-down process. It is confirmed that para-hydrogen always exists in the equilibrium concentration because of the installation of an ortho-para hydrogen convertor. Propagation characteristics of temperature fluctuation were measured by temporarily changing the heater power under off-beam condition to clarify the effects of a heater control for thermal compensation on the feed temperature fluctuation. The experimental data gave an allowable temperature fluctuation of 1.05 K. It is clarified through a 286-kW and a 524-kW proton beam operations that the heater control would be applicable for the 1-MW proton beam operation by extrapolating from the experimental data.

  16. Note: Detector collimators for the nanoscale ordered materials diffractometer instrument at the Spallation Neutron Source

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tamalonis, A.; Weber, J. K. R.; Neuefeind, J. C.; Carruth, J.; Skinner, L. B.; Alderman, O. L. G.; Benmore, C. J.

    2015-09-09

    We constructed and tested five neutron collimator designs using the nanoscale ordered materials diffractometer (NOMAD) instrument. Collimators were made from High Density PolyEthylene (HDPE) or 5% borated HDPE. In all cases, collimators improved the signal to background ratio and reduced detection of secondary scattering. Moreover, in the Q-range 10-20 Å-1, signal to background ratio improved by factors of approximately 1.6 and 2.0 for 50 and 100 mm deep collimators, respectively. In the Q-range 40-50 Å-1, the improvement factors were 1.8 and 2.7. Secondary scattering as measured at Q similar to 9.5 Å-1 was significantly decreased when the collimators were installed.

  17. Note: Detector collimators for the nanoscale ordered materials diffractometer instrument at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Tamalonis, A.; Weber, J. K. R. Alderman, O. L. G.; Neuefeind, J. C.; Carruth, J.; Skinner, L. B.; Benmore, C. J.

    2015-09-15

    Five neutron collimator designs were constructed and tested at the nanoscale ordered materials diffractometer (NOMAD) instrument. Collimators were made from High Density PolyEthylene (HDPE) or 5% borated HDPE. In all cases, collimators improved the signal to background ratio and reduced detection of secondary scattering. In the Q-range 10-20 Å{sup −1}, signal to background ratio improved by factors of approximately 1.6 and 2.0 for 50 and 100 mm deep collimators, respectively. In the Q-range 40-50 Å{sup −1}, the improvement factors were 1.8 and 2.7. Secondary scattering as measured at Q ∼ 9.5 Å{sup −1} was significantly decreased when the collimators were installed.

  18. Development of nanodiamond foils for H- stripping to Support the Spallation Neutron Source (SNS) using hot filament chemical vapor deposition

    SciTech Connect (OSTI)

    Vispute, R D; Ermer, Henry K; Sinsky, Phillip; Seiser, Andrew; Shaw, Robert W; Wilson, Leslie L

    2014-01-01

    Thin diamond foils are needed in many particle accelerator experiments regarding nuclear and atomic physics, as well as in some interdisciplinary research. Particularly, nanodiamond texture is attractive for this purpose as it possesses a unique combination of diamond properties such as high thermal conductivity, mechanical strength and high radiation hardness; therefore, it is a potential material for energetic ion beam stripper foils. At the ORNL Spallation Neutron Source (SNS), the installed set of foils must be able to survive a nominal five-month operation period, without the need for unscheduled costly shutdowns and repairs. Thus, a small foil about the size of a postage stamp is critical to the operation of SNS and similar sources in U.S. laboratories and around the world. We are investigating nanocrystalline, polycrystalline and their admixture films fabricated using a hot filament chemical vapor deposition (HFCVD) system for H- stripping to support the SNS at Oak Ridge National Laboratory. Here we discuss optimization of process variables such as substrate temperature, process gas ratio of H2/Ar/CH4, substrate to filament distance, filament temperature, carburization conditions, and filament geometry to achieve high purity diamond foils on patterned silicon substrates with manageable intrinsic and thermal stresses so that they can be released as free standing foils without curling. An in situ laser reflectance interferometry tool (LRI) is used for monitoring the growth characteristics of the diamond thin film materials. The optimization process has yielded free standing foils with no pinholes. The sp3/sp2 bonds are controlled to optimize electrical resistivity to reduce the possibility of surface charging of the foils. The integrated LRI and HFCVD process provides real time information on the growth of films and can quickly illustrate growth features and control film thickness. The results are discussed in the light of development of nanodiamond foils that

  19. Producing persistent, high-current, high-duty-factor H{sup -} beams for routine 1 MW operation of Spallation Neutron Source (invited)

    SciTech Connect (OSTI)

    Stockli, Martin P.; Han, B. X.; Hardek, T. W.; Kang, Y. W.; Murray, S. N.; Pennisi, T. R.; Piller, C.; Santana, M.; Welton, R.

    2012-02-15

    Since 2009, the Spallation Neutron Source (SNS) has been producing neutrons with ion beam powers near 1 MW, which requires the extraction of {approx}50 mA H{sup -} ions from the ion source with a {approx}5% duty factor. The 50 mA are achieved after an initial dose of {approx}3 mg of Cs and heating the Cs collar to {approx}170 deg. C. The 50 mA normally persist for the entire 4-week source service cycles. Fundamental processes are reviewed to elucidate the persistence of the SNS H{sup -} beams without a steady feed of Cs and why the Cs collar temperature may have to be kept near 170 deg. C.

  20. ORNL Neutron Sciences Annual Report for 2007

    SciTech Connect (OSTI)

    Anderson, Ian S; Horak, Charlie M; Counce, Deborah Melinda; Ekkebus, Allen E

    2008-07-01

    This is the first annual report of the Oak Ridge National Laboratory Neutron Sciences Directorate for calendar year 2007. It describes the neutron science facilities, current developments, and future plans; highlights of the year's activities and scientific research; and information on the user program. It also contains information about education and outreach activities and about the organization and staff. The Neutron Sciences Directorate is responsible for operation of the High Flux Isotope Reactor and the Spallation Neutron Source. The main highlights of 2007 were highly successful operation and instrument commissioning at both facilities. At HFIR, the year began with the reactor in shutdown mode and work on the new cold source progressing as planned. The restart on May 16, with the cold source operating, was a significant achievement. Furthermore, measurements of the cold source showed that the performance exceeded expectations, making it one of the world's most brilliant sources of cold neutrons. HFIR finished the year having completed five run cycles and 5,880 MWd of operation. At SNS, the year began with 20 kW of beam power on target; and thanks to a highly motivated staff, we reached a record-breaking power level of 183 kW by the end of the year. Integrated beam power delivered to the target was 160 MWh. Although this is a substantial accomplishment, the next year will bring the challenge of increasing the integrated beam power delivered to 887 MWh as we chart our path toward 5,350 MWh by 2011.

  1. Neutron Scattering Facilities | U.S. DOE Office of Science (SC...

    Office of Science (SC) Website

    High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory The HFIR facility is the United States' highest flux reactor-based neutron source, and is a major neutron ...

  2. {sup 48}Ti(n,xnpa{gamma}) reaction cross sections using spallation neutrons for E{sub n} = 1 to 20 MeV

    SciTech Connect (OSTI)

    Dashdorj, D; Mitchell, G E; Garrett, P E; Agvaanluvsan, U; Becker, J A; Bernstein, L A; Cooper, J R; Hoffman, R D; Younes, W; Devlin, N; Fotiades, N; Nelson, R O

    2005-01-06

    {gamma}-ray excitation functions have been measured for the interaction of fast neutrons with {sup 48}Ti (neutron energy from 1 MeV to 250 MeV). The Los Alamos National Laboratory spallation neutron source, at the LANSCE/WNR facility, provided a ''white'' neutron beam which is produced by bombarding a natural W target with a pulsed proton beam. The prompt-reaction {gamma} rays were measured with the large-scale Compton-suppressed Ge spectrometer, GEANIE. Neutron energies were determined by the time-of-flight technique. Excitation functions were converted to partial {gamma}-ray cross sections, taking into account the dead-time correction, the target thickness, the detector efficiency, and neutron flux (monitored with an in-line fission chamber). The data analysis is presented here for neutron energies between 1 to 20 MeV. Partial {gamma}-ray cross sections for transitions in {sup 47,48}Ti, {sup 48}Sc, and {sup 45}Ca have been determined. These results are compared to Hauser-Feshbach predictions calculated using the STAPRE code, which includes compound nuclear and pre-equilibrium emission. The partial cross sections for {gamma} rays, whose discrete {gamma}-ray cascade path leads to the ground state in {sup 48}Ti, {sup 47}Ti, {sup 48}Sc, and {sup 45}Ca have been summed to obtain estimates of the lower limits for reaction cross sections. Partial cross sections for unobserved {gamma}-rays are predicted from the STAPRE code. These lower limits are combined with Hauser-Feshbach calculations to deduce {sup 48}Ti(n,n'){sup 48}Ti, {sup 48}Ti(n,2n){sup 47}Ti, {sup 48}Ti(n,p){sup 48}Sc, and {sup 48}Ti(n,{alpha}){sup 45}Ca reaction channel cross sections.

  3. High Flux Isotope Reactor | Neutron Science at ORNL

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

    HFIR is also used for medical, industrial, and research isotope production; research on severe neutron damage to materials; and neutron activation analysis to examine trace ...

  4. Spallation radiation effects in materials

    SciTech Connect (OSTI)

    Mansur, L.K.; Farrell, K.; Wechsler, M.S.

    1996-06-01

    Spallation refers to the process whereby particles (chiefly neutrons) are ejected from nuclei upon bombardment by high-energy protons. Spallation neutron sources (SNS`s) use these neutrons for neutron scattering and diffraction research, and SNS`s are proposed as the basis for systems for tritium production and transmutation of nuclear waste. Materials in SNS`s are exposed to the incident proton beam (energies typically about 1000 MeV) and to the spallation neutrons (spectrum of energies extending up to about 1000 MeV). By contrast the fission neutrons in nuclear reactors have an average energy of only about 2 MeV, and the neutrons in fusion reactors would have energies below about 14 MeV. Furthermore, the protons and neutrons in SNS`s for scattering and diffraction research are pulsed at frequencies of about 10 to 60 Hz, from which significant changes in the kinetics of point and extended defects may be expected. In addition, much higher transmutation rates occur in SNS-irradiated materials, On the whole, then, significant differences in microstructural development and macroscopic properties may result upon exposure in SNS systems, as compared with fission and fusion irradiations. In a more general sense, subjecting materials to new radiation environments has almost routinely led to new discoveries. To the extent that data are avaiable, however, the spallation environment appears to increase the degree of damage without introducing totally new effects. The first part of this presentation is an overview of radiation effects in materials, outlining essential concepts and property changes and their physical bases. This background is followed by a description of SNS irradiation environments and the effects on materials of exposure to these environments. A special discussion is given of the selection of target (e.g., liquid mercury), container (e.g., austenitic stainless steel or ferritic/martensitic steel), and structural materials in SNS systems.

  5. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    SciTech Connect (OSTI)

    Overbury, Steven {Steve} H; Coates, Leighton; Herwig, Kenneth W; Kidder, Michelle

    2011-10-01

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  6. Upgraded HFIR Fuel Element Welding System

    SciTech Connect (OSTI)

    Sease, John D

    2010-02-01

    The welding of aluminum-clad fuel plates into aluminum alloy 6061 side plate tubing is a unique design feature of the High Flux Isotope Reactor (HFIR) fuel assemblies as 101 full-penetration circumferential gas metal arc welds (GMAW) are required in the fabrication of each assembly. In a HFIR fuel assembly, 540 aluminum-clad fuel plates are assembled into two nested annular fuel elements 610 mm (24-inches) long. The welding process for the HFIR fuel elements was developed in the early 1960 s and about 450 HFIR fuel assemblies have been successfully welded using the GMAW process qualified in the 1960 s. In recent years because of the degradation of the electronic and mechanical components in the old HFIR welding system, reportable defects in plate attachment or adapter welds have been present in almost all completed fuel assemblies. In October 2008, a contract was awarded to AMET, Inc., of Rexburg, Idaho, to replace the old welding equipment with standard commercially available welding components to the maximum extent possible while maintaining the qualified HFIR welding process. The upgraded HFIR welding system represents a major improvement in the welding system used in welding HFIR fuel elements for the previous 40 years. In this upgrade, the new inner GMAW torch is a significant advancement over the original inner GMAW torch previously used. The innovative breakthrough in the new inner welding torch design is the way the direction of the cast in the 0.762 mm (0.030-inch) diameter aluminum weld wire is changed so that the weld wire emerging from the contact tip is straight in the plane perpendicular to the welding direction without creating any significant drag resistance in the feeding of the weld wire.

  7. Analysis of structure and deformation behavior of AISI 316L tensile specimens from the second operational target module at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Gussev, Maxim N.; McClintock, David A.; Garner, Frank

    2015-08-05

    In an earlier publication, tensile testing was performed on specimens removed from the first two operational targets of the Spallation Neutron Source (SNS). There were several anomalous features in the results. First, some specimens had very large elongations (up to 57%) while others had significantly smaller values. Second, there was a larger than the usual amount of data scatter in the elongation results. Third, the stress-strain diagrams of nominally similar specimens spanned a wide range of behavior ranging from expected irradiation-induced hardening to varying levels of force drop after yield point and indirect signs of "traveling deformation wave" behavior associated with strain-induced martensite formation. To investigate the cause(s) of such variable tensile behavior, several specimens from Target 2, spanning the range of observed tensile behavior, were chosen for detailed microstructural examination using electron backscattering analysis (EBSD). It was also shown that the steel employed in the construction of the target contained an unexpected bimodal grain size distribution, containing very large out-of-specification grains surrounded by necklaces of grains of within-specification sizes. The large grains were frequently comparable to the width of the gauge section of the tensile specimen. Moreover, the propensity to form martensite during deformation was shown to be accelerated by radiation but also to be very sensitive to the relative orientation of the grains with respect to the tensile axis. Specimens having large grains in the gauge that were most favorably oriented for production of martensite strongly exhibited the traveling deformation wave phenomenon, while those specimens with less favorably oriented grains had lesser or no degree of the wave effect, thereby accounting for the larger than expected data scatter.

  8. Analysis of structure and deformation behavior of AISI 316L tensile specimens from the second operational target module at the Spallation Neutron Source

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gussev, Maxim N.; McClintock, David A.; Garner, Frank

    2015-08-05

    In an earlier publication, tensile testing was performed on specimens removed from the first two operational targets of the Spallation Neutron Source (SNS). There were several anomalous features in the results. First, some specimens had very large elongations (up to 57%) while others had significantly smaller values. Second, there was a larger than the usual amount of data scatter in the elongation results. Third, the stress-strain diagrams of nominally similar specimens spanned a wide range of behavior ranging from expected irradiation-induced hardening to varying levels of force drop after yield point and indirect signs of "traveling deformation wave" behavior associatedmore » with strain-induced martensite formation. To investigate the cause(s) of such variable tensile behavior, several specimens from Target 2, spanning the range of observed tensile behavior, were chosen for detailed microstructural examination using electron backscattering analysis (EBSD). It was also shown that the steel employed in the construction of the target contained an unexpected bimodal grain size distribution, containing very large out-of-specification grains surrounded by necklaces of grains of within-specification sizes. The large grains were frequently comparable to the width of the gauge section of the tensile specimen. Moreover, the propensity to form martensite during deformation was shown to be accelerated by radiation but also to be very sensitive to the relative orientation of the grains with respect to the tensile axis. Specimens having large grains in the gauge that were most favorably oriented for production of martensite strongly exhibited the traveling deformation wave phenomenon, while those specimens with less favorably oriented grains had lesser or no degree of the wave effect, thereby accounting for the larger than expected data scatter.« less

  9. Proceedings of the international workshop on spallation materials technology

    SciTech Connect (OSTI)

    Mansur, L.K.; Ullmaier, H. [comps.] [comps.

    1996-10-01

    This document contains papers which were presented at the International Workshop on Spallation Materials Technology. Topics included: overviews and thermal response; operational experience; materials experience; target station and component design; particle transport and damage calculations; neutron sources; and compatibility.

  10. Impact of HFIR LEU Conversion on Beryllium Reflector Degradation Factors

    SciTech Connect (OSTI)

    Ilas, Dan

    2013-10-01

    An assessment of the impact of low enriched uranium (LEU) conversion on the factors that may cause the degradation of the beryllium reflector is performed for the High Flux Isotope Reactor (HFIR). The computational methods, models, and tools, comparisons with previous work, along with the results obtained are documented and discussed in this report. The report documents the results for the gas and neutronic poison production, and the heating in the beryllium reflector for both the highly enriched uranium (HEU) and LEU HFIR configurations, and discusses the impact that the conversion to LEU may have on these quantities. A time-averaging procedure was developed to calculate the isotopic (gas and poisons) production in reflector. The sensitivity of this approach to different approximations is gauged and documented. The results show that the gas is produced in the beryllium reflector at a total rate of 0.304 g/cycle for the HEU configuration; this rate increases by ~12% for the LEU case. The total tritium production rate in reflector is 0.098 g/cycle for the HEU core and approximately 11% higher for the LEU core. A significant increase (up to ~25%) in the neutronic poisons production in the reflector during the operation cycles is observed for the LEU core, compared to the HEU case, for regions close to the core s horizontal midplane. The poisoning level of the reflector may increase by more than two orders of magnitude during long periods of downtime. The heating rate in the reflector is estimated to be approximately 20% lower for the LEU core than for the HEU core. The decrease is due to a significantly lower contribution of the heating produced by the gamma radiation for the LEU core. Both the isotopic (gas and neutronic poisons) production and the heating rates are spatially non-uniform throughout the beryllium reflector volume. The maximum values typically occur in the removable reflector and close to the midplane.

  11. A Survey of Students from the National School on Neutron and X-ray Scattering: Communication Habits and Preferences

    SciTech Connect (OSTI)

    Bryant, Rebecca

    2010-12-01

    Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world. And the SNS is one of the world's most intense pulse neutron beams. Management of these resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD started conducting the National School on Neutron and X-ray Scattering (NXS) in conjunction with the Advanced Photon Source (APS) at Argonne National Laboratory in 2007. This survey was conducted to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites and social media, for communicating with students about neutron science The survey was conducted in two phases using a classic qualitative investigation to confirm language and content followed by a survey designed to quantify issues, assumptions, and working hypotheses. Phase I consisted of a focus group in late June 2010 with students attending NXS. The primary intent of the group was to inform development of an online survey. Phase two consisted of an online survey that was developed and pre-tested in July 2010 and launched on August 9, 2010 and remained in the field until September 9, 2010. The survey achieved an overall response rate of 48% for a total of 157 completions. The objective of this study is to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites, social media

  12. Transmutation-induced embrittlement of V-Ti-Ni and V-Ni alloys in HFIR

    SciTech Connect (OSTI)

    Ohnuki, S.; Takahashi, H.; Garner, F.A.; Pawel, J.E.

    1996-04-01

    Vanadium, V-1Ni, V-10Ti and V-10Ti-1Ni (at %) were irradiated in HFIR to doses ranging from 18 to 30 dpa and temperatures between 300 and 600C. Since the irradiation was conducted in a highly thermalized neutron spectrum without shielding against thermal neutrons, significant levels of chromium (15-22%) were formed by transmutation. The addition of such large chromium levels strongly elevated the ductile to brittle transition temperature. At higher irradiation temperatures radiation-induced segregation of transmutant Cr and solute Ti at specimen surfaces leads to strong increases in the density of the alloy.

  13. Upgrading the HFIR Thermal-Hydraulic Legacy Code Using COMSOL...

    Office of Scientific and Technical Information (OSTI)

    Modernization of the High Flux Isotope Reactor (HFIR) thermal-hydraulic (TH) design and safety analysis capability is an important step in preparation for the conversion of the ...

  14. Upgrading the HFIR Thermal-Hydraulic Legacy Code Using COMSOL

    SciTech Connect (OSTI)

    Bodey, Isaac T [ORNL] [ORNL; Arimilli, Rao V [ORNL] [ORNL; Freels, James D [ORNL] [ORNL

    2010-01-01

    Modernization of the High Flux Isotope Reactor (HFIR) thermal-hydraulic (TH) design and safety analysis capability is an important step in preparation for the conversion of the HFIR core from a high enriched uranium (HEU) fuel to a low enriched uranium (LEU) fuel. Currently, an important part of the HFIR TH analysis is based on the legacy Steady State Heat Transfer Code (SSHTC), which adds much conservatism to the safety analysis. The multi-dimensional multi-physics capabilities of the COMSOL environment allow the analyst to relax the number and magnitude of conservatisms, imposed by the SSHTC, to present a more physical model of the TH aspect of the HFIR.

  15. 2010 Neutron Review: ORNL Neutron Sciences Progress Report

    SciTech Connect (OSTI)

    Bardoel, Agatha A; Counce, Deborah M; Ekkebus, Allen E; Horak, Charlie M; Nagler, Stephen E; Kszos, Lynn A

    2011-06-01

    During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown over the last year, so has promising neutron scattering research. This was an exciting year in science, technology, and operations. Some topics discussed are: (1) HFIR and SNS Experiments Take Gordon Battelle Awards for Scientific Discovery - Battelle Memorial Institute presented the inaugural Gordon Battelle Prizes for scientific discovery and technology impact in 2010. Battelle awards the prizes to recognize the most significant advancements at national laboratories that it manages or co-manages. (2) Discovery of Element 117 - As part of an international team of scientists from Russia and the United States, HFIR staff played a pivotal role in the discovery by generating the berkelium used to produce the new element. A total of six atoms of ''ununseptium'' were detected in a two-year campaign employing HFIR and the Radiochemical Engineering Development Center at Oak Ridge National Laboratory (ORNL) and the heavy-ion accelerator capabilities at the Joint Institute for Nuclear Research in Dubna, Russia. The discovery of the new element expands the understanding of the properties of nuclei at extreme numbers of protons and neutrons. The production of a new element and observation of 11 new heaviest isotopes demonstrate the increased stability of super-heavy elements with increasing neutron numbers and provide the strongest evidence to date for the existence of an island of enhanced stability for super-heavy elements. (3) Studies of Iron-Based High-Temperature Superconductors - ORNL applied its distinctive capabilities in neutron scattering, chemistry, physics, and computation to detailed studies of the magnetic excitations of iron-based superconductors (iron pnictides and

  16. Source Terms for HFIR Beam Tube Shielding Analyses, and a Complete Shielding Analysis of the HB-3 Tube

    SciTech Connect (OSTI)

    Bucholz, J.A.

    2000-07-01

    The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory is in the midst of a massive upgrade program to enhance experimental facilities. The reactor presently has four horizontal experimental beam tubes, all of which will be replaced or redesigned. The HB-2 beam tube will be enlarged to support more guide tubes, while the HB-4 beam tube will soon include a cold neutron source.

  17. The European Spallation Source

    SciTech Connect (OSTI)

    Peggs, S; Eshraqi, M; Hahn, H; Jansson, A; Lindroos, M; Ponton, A; Rathsman, K; Trahern, G; Bousso, S; Calaga, R; Devanz, G; Duperrier, R D; Eguia, J; Gammino, S; Moller, S P; Oyon, C; Ruber, R.J.M.Y.

    2011-03-01

    The European Spallation Source (ESS) is a 5 MW, 2.5 GeV long pulse proton linac, to be built and commissioned in Lund, Sweden. The Accelerator Design Update (ADU) project phase is under way, to be completed at the end of 2012 by the delivery of a Technical Design Report. Improvements to the 2003 ESS design will be summarised, and the latest design activities will be presented.

  18. High power neutron production targets

    SciTech Connect (OSTI)

    Wender, S.

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  19. Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

    SciTech Connect (OSTI)

    Renfro, David; Chandler, David; Cook, David; Ilas, Germina; Jain, Prashant; Valentine, Jennifer

    2014-10-30

    Engineering design studies of the feasibility of conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL) as part of an effort sponsored by the U.S. Department of Energy’s Global Threat Reduction Initiative (GTRI)/Reduced Enrichment for Research and Test Reactors (RERTR) program. The fuel type selected by the program for the conversion of the five high-power research reactors in the U.S. that still use HEU fuel is a new U-Mo monolithic fuel. Studies by ORNL have previously indicated that HFIR can be successfully converted using the new fuel provided (1) the reactor power can be increased from 85 MW to 100 MW and (2) the fuel can be fabricated to a specific reference design. Fabrication techniques for the new fuel are under development by the program but are still immature, especially for the “complex” aspects of the HFIR fuel design. In FY 2012, the program underwent a major shift in focus to emphasize developing and qualifying processes for the fabrication of reliable and affordable LEU fuel. In support of this new focus and in an effort to ensure that the HFIR fuel design is as suitable for reliable fabrication as possible, ORNL undertook the present study to propose and evaluate several alternative design features. These features include (1) eliminating the fuel zone axial contouring in the previous reference design by substituting a permanent neutron absorber in the lower unfueled region of all of the fuel plates, (2) relocating the burnable neutron absorber from the fuel plates of the inner fuel element to the side plates of the inner fuel element (the fuel plates of the outer fuel element do not contain a burnable absorber), (3) relocating the fuel zone inside the fuel plate to be centered on the centerline of the depth of the plate, and (4) reshaping the radial contour of the relocated fuel zone to be symmetric about this centerline. The

  20. Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

    SciTech Connect (OSTI)

    Renfro, David G; Chandler, David; Cook, David Howard; Ilas, Germina; Jain, Prashant K; Valentine, Jennifer R

    2014-11-01

    Engineering design studies of the feasibility of conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL) as part of an effort sponsored by the U.S. Department of Energy s Global Threat Reduction Initiative (GTRI)/Reduced Enrichment for Research and Test Reactors (RERTR) program. The fuel type selected by the program for the conversion of the five high-power research reactors in the U.S. that still use HEU fuel is a new U-Mo monolithic fuel. Studies by ORNL have previously indicated that HFIR can be successfully converted using the new fuel provided (1) the reactor power can be increased from 85 MW to 100 MW and (2) the fuel can be fabricated to a specific reference design. Fabrication techniques for the new fuel are under development by the program but are still immature, especially for the complex aspects of the HFIR fuel design. In FY 2012, the program underwent a major shift in focus to emphasize developing and qualifying processes for the fabrication of reliable and affordable LEU fuel. In support of this new focus and in an effort to ensure that the HFIR fuel design is as suitable for reliable fabrication as possible, ORNL undertook the present study to propose and evaluate several alternative design features. These features include (1) eliminating the fuel zone axial contouring in the previous reference design by substituting a permanent neutron absorber in the lower unfueled region of all of the fuel plates, (2) relocating the burnable neutron absorber from the fuel plates of the inner fuel element to the side plates of the inner fuel element (the fuel plates of the outer fuel element do not contain a burnable absorber), (3) relocating the fuel zone inside the fuel plate to be centered on the centerline of the depth of the plate, and (4) reshaping the radial contour of the relocated fuel zone to be symmetric about this centerline. The present

  1. The SNS/HFIR Web Portal System for SANS

    SciTech Connect (OSTI)

    Campbell, Stuart I; Miller, Stephen D; Bilheux, Jean-Christophe; Reuter, Michael A; Peterson, Peter F; Kohl, James Arthur; Trater, James R; Vazhkudai, Sudharshan S; Lynch, Vickie E

    2010-01-01

    In a busy world, continuing with the status-quo, to do things the way we are already familiar, often seems to be the most efficient way to conduct our work. We look for the value-add to decide if investing in a new method is worth the effort. How shall we evaluate if we have reached this tipping point for change? For contemporary researchers, understanding the properties of the data is a good starting point. The new generation of neutron scattering instruments being built are higher resolution and produce one or more orders of magnitude larger data than the previous generation of instruments. For instance, we have grown out of being able to perform some important tasks with our laptops the data are too big and the computations would simply take too long. These large datasets can be problematic as facility users now begin to grapple with many of the same issues faced by more established computing communities. These issues include data access, management, and movement, data format standards, distributed computing, and collaboration among others. The Neutron Science Portal has been architected, designed, and implemented to provide users with an easy-to-use interface for managing and processing data, while also keeping an eye on meeting modern cybersecurity requirements imposed on institutions. The cost of entry for users has been lowered by utilizing a web interface providing access to backend portal resources. Users can browse or search for data which they are allowed to see, data reduction applications can be run without having to load the software, sample activation calculations can be performed for SNS and HFIR beamlines, McStas simulations can be run on TeraGrid and ORNL computers, and advanced analysis applications such as those being produced by the DANSE project can be run. Behind the scenes is a live cataloging system which automatically catalogs and archives experiment data via the data management system, and provides proposal team members access to their

  2. A Record Number of Proposals Received for HFIR and SNS (Journal...

    Office of Scientific and Technical Information (OSTI)

    A Record Number of Proposals Received for HFIR and SNS Citation Details In-Document Search Title: A Record Number of Proposals Received for HFIR and SNS No abstract prepared. ...

  3. Revision of HFIR (High Flux Isotope Reactor) operating procedures

    SciTech Connect (OSTI)

    McGinty, D.M.

    1987-01-23

    This report documents modifications to the facility and changes in some operating procedures for the High Flux Isotope Reactor (HFIR). The topics covered include: Reactor Operation, Reactor Start-up, Reactor Safety Systems, Reactor Control Systems, Reporting Requirements, and Administrative Procedures. (FI)

  4. Decommissioning and PIE of the MEGAPIE spallation target

    SciTech Connect (OSTI)

    Latge, C.; Henry, J.; Wohlmuther, M.; Dai, Y.; Gavillet, D.; Hammer, B.; Heinitz, S.; Neuhausen, J.; Schumann, D.; Thomsen, K.; Tuerler, A.; Wagner, W.; Gessi, A.; Guertin, A.; Konstantinovic, M.; Lindau, R.; Maloy, S.; Saito, S.

    2013-07-01

    A key experiment in the Accelerated Driven Systems roadmap, the MEGAwatt PIlot Experiment (MEGAPIE) (1 MW) was initiated in 1999 in order to design and build a liquid lead-bismuth spallation target, then to operate it into the Swiss spallation neutron facility SINQ at Paul Scherrer Institute. The target has been designed, manufactured, and tested during integral tests, before irradiation carried out end of 2006. During irradiation, neutron and thermo hydraulic measurements were performed allowing deep interpretation of the experiment and validation of the models used during design phase. The decommissioning, Post Irradiation Examinations and waste management phases were defined properly. The phases dedicated to cutting, sampling, cleaning, waste management, samples preparation and shipping to various laboratories were performed by PSI teams: all these phases constitute a huge work, which allows now to perform post-irradiation examination (PIE) of structural material, irradiated in relevant conditions. Preliminary results are presented in the paper, they concern chemical characterization. The following radio-nuclides have been identified by ?-spectrometry: {sup 60}Co, {sup 101}Rh, {sup 102}Rh, {sup 108m}Ag, {sup 110m}Ag, {sup 133}Ba, {sup 172}Hf/Lu, {sup 173}Lu, {sup 194}Hg/Au, {sup 195}Au, {sup 207}Bi. For some of these nuclides the activities can be easily evaluated from ?-spectrometry results ({sup 207}Bi, {sup 194}Hg/Au), while other nuclides can only be determined after chemical separations ({sup 108m}Ag, {sup 110m}Ag, {sup 195}Au, {sup 129}I, {sup 36}Cl and ?-emitting {sup 208-210}Po). The concentration of {sup 129}I is lower than expected. The chemical analysis already performed on spallation and corrosion products in the lead-bismuth eutectic (LBE) are very relevant for further applications of LBE as a spallation media and more generally as a coolant.

  5. Neutron scattering at the high flux isotope reactor at Oak Ridge National Laboratory

    SciTech Connect (OSTI)

    Yethiraj, M.; Fernandez-Baca, J.A.

    1995-03-01

    Since its beginnings in Oak Ridge and Argonne in the late 1940`s, neutron scattering has been established as the premier tool to study matter in its various states. Since the thermal neutron wavelength is of the same order of magnitude as typical atomic spacings and because they have comparable energies to those of atomic excitations in solids, both structure and dynamics of matter can be studied via neutron scattering. The High Flux Isotope Reactor (HFIR) provides an intense source of neutrons with which to carry out these measurements. This paper summarizes the available neutron scattering facilities at the HFIR.

  6. Challenges and design solutions of the liquid hydrogen circuit at the European Spallation Source

    SciTech Connect (OSTI)

    Gallimore, S.; Nilsson, P.; Sabbagh, P.; Takibayev, A.; Weisend II, J. G.; Beler, Y.; Klaus, M.

    2014-01-29

    The European Spallation Source (ESS), Lund, Sweden will be a 5MW long-pulse neutron spallation research facility and will enable new opportunities for researchers in the fields of life sciences, energy, environmental technology, cultural heritage and fundamental physics. Neutrons are produced by accelerating a high-energy proton beam into a rotating helium-cooled tungsten target. These neutrons pass through moderators to reduce their energy to an appropriate range (< 5 meV for cold neutrons); two of which will use liquid hydrogen at 17 K as the moderating and cooling medium. There are several technical challenges to overcome in the design of a robust system that will operate under such conditions, not least the 20 kW of deposited heat. These challenges and the associated design solutions will be detailed in this paper.

  7. Meeting notes of the High Flux Isotope Reactor (HFIR) futures group

    SciTech Connect (OSTI)

    Houser, M.M.

    1995-08-01

    This report is a compilation of the notes from the ten meetings. The group charter is: (1) to identify and characterize the range of possibilities and necessities for keeping the HFIR operating for at least the next 15 years; (2) to identify and characterize the range of possibilities for enhancing the scientific and technical utility of the HFIR; (3) to evaluate the benefits or impacts of these possibilities on the various scientific fields that use the HFIR or its products; (4) to evaluate the benefits or impacts on the operation and maintenance of the HFIR facility and the regulatory requirements; (5) to estimate the costs, including operating costs, and the schedules, including downtime, for these various possibilities; and one possible impact of proposed changes may be to stimulate increased pressure for a reduced enrichment fuel for HFIR.

  8. Production of Actinium-225 via High Energy Proton Induced Spallation...

    Office of Scientific and Technical Information (OSTI)

    ... Language: English Subject: 07 ISOTOPES AND RADIATION SOURCES; 38 RADIATION CHEMISTRY, ... 226; REACTION KINETICS; SPALLATION; THORIUM; THORIUM 232; URANIUM 233 spallation, ...

  9. Development of a Hydrothermal Spallation Drilling System for...

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

    Hydrothermal Spallation Drilling System for EGS Development of a Hydrothermal Spallation Drilling System for EGS Project objective: Build and demonstrate a working prototype ...

  10. Nuclear Transmutations in HFIR's Beryllium Reflector and Their Impact on Reactor Operation and Reflector Disposal

    SciTech Connect (OSTI)

    Chandler, David [ORNL; Maldonado, G Ivan [ORNL; Primm, Trent [ORNL; Proctor, Larry Duane [ORNL

    2012-01-01

    The High Flux Isotope Reactor located at the Oak Ridge National Laboratory utilizes a large cylindrical beryllium reflector that is subdivided into three concentric regions and encompasses the compact reactor core. Nuclear transmutations caused by neutron activation occur in the beryllium reflector regions, which leads to unwanted neutron absorbing and radiation emitting isotopes. During the past year, two topics related to the HFIR beryllium reflector were reviewed. The first topic included studying the neutron poison (helium-3 and lithium-6) buildup in the reflector regions and its affect on beginning-of-cycle reactivity. A new methodology was developed to predict the reactivity impact and estimated symmetrical critical control element positions as a function of outage time between cycles due to helium-3 buildup and was shown to be in better agreement with actual symmetrical critical control element position data than the current methodology. The second topic included studying the composition of the beryllium reflector regions at discharge as well as during decay to assess the viability of transporting, storing, and ultimately disposing the reflector regions currently stored in the spent fuel pool. The post-irradiation curie inventories were used to determine whether the reflector regions are discharged as transuranic waste or become transuranic waste during the decay period for disposal purposes and to determine the nuclear hazard category, which may affect the controls invoked for transportation and temporary storage. Two of the reflector regions were determined to be transuranic waste at discharge and the other region was determined to become transuranic waste in less than 2 years after being discharged due to the initial uranium content (0.0044 weight percent uranium). It was also concluded that all three of the reflector regions could be classified as nuclear hazard category 3 (potential for localized consequences only).

  11. Lattice Vibrations Boost Demagnetization Entropy in Shape Memory...

    Office of Scientific and Technical Information (OSTI)

    measure the lattice dynamics in the MC material Ni45Co5Mn36.6In13.4. Upon heating across ... Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Spallation Neutron ...

  12. LANSCE | International Collaboration on Advanced Neutron Sources...

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

    ICANS-XIX Paul Scherrer Institit (PSI) Gindelwald, Switzerland March 8012, 2010 ICANS-XVIII China Spallation Neutron Source, Beijing, China, April 26-29, 2007 ICANS-XVII Bishop's ...

  13. Electrostatic levitation facility optimized for neutron diffraction...

    Office of Scientific and Technical Information (OSTI)

    studies of high temperature liquids at a spallation neutron source Authors: Mauro, N. A. 1 ; Vogt, A. J. 2 Search DOE PAGES for author "Vogt, A. J." Search DOE PAGES for ...

  14. Neutrons for technology and science

    SciTech Connect (OSTI)

    Aeppli, G.

    1995-10-01

    We reviewed recent work using neutrons generated at nuclear reactors an accelerator-based spallation sources. Provided that large new sources become available, neutron beams will continue to have as great an impact on technology and science as in the past.

  15. Status of lithium-filled specimen subcapsules for the HFIR-MFE-RB10J experiment

    SciTech Connect (OSTI)

    Robertson, J.P.; Howell, M.; Lenox, K.E.

    1998-09-01

    The HFIR-MFE-RB-10J experiment will be irradiated in a Removable Beryllium position in the HFIR for 10 reactor cycles, accumulating approximately 5 dpa in steel. The upper region of the capsule contains two lithium-filled subcapsules containing vanadium specimens. This report describes the techniques developed to achieve a satisfactory lithium fill with a specimen occupancy of 26% in each subcapsule.

  16. Design and implementation of a multiaxial loading capability during heating on an engineering neutron diffractometer

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Benafan, O.; Padula, S. A.; Skorpenske, H. D.; An, K.; Vaidyanathan, R.

    2014-10-02

    Here we discuss a gripping capability that was designed, implemented, and tested for in situ neutron diffraction measurements during multiaxial loading and heating on the VULCAN engineering materials diffractometer at the spallation neutron source at Oak Ridge National Laboratory.

  17. The SNS/HFIR Web Portal System How Can it Help Me?

    SciTech Connect (OSTI)

    Miller, Stephen D; Geist, Al; Herwig, Kenneth W; Peterson, Peter F; Reuter, Michael A; Ren, Shelly; Bilheux, Jean-Christophe; Campbell, Stuart I; Kohl, James Arthur; Vazhkudai, Sudharshan S; Cobb, John W; Lynch, Vickie E; Chen, Meili; Trater, James R

    2010-01-01

    Abstract. In a busy world, continuing with the status-quo, to do things the way we are already familiar, often seems to be the most efficient way to conduct our work. We look for the value-add to decide if investing in a new method is worth the effort. How shall we evaluate if we have reached this tipping point for change? For contemporary researchers, understanding the properties of the data is a good starting point. The new generation of neutron scattering instruments being built are higher resolution and produce one or more orders of magnitude larger data than the previous generation of instruments. For instance, we have grown out of being able to perform some important tasks with our laptops the data are too big and the computations would simply take too long. These large datasets can be problematic as facility users now begin to grapple with many of the same issues faced by more established computing communities. These issues include data access, management, and movement, data format standards, distributed computing, and collaboration among others. The Neutron Science Portal has been architected, designed, and implemented to provide users with an easy-to-use interface for managing and processing data, while also keeping an eye on meeting modern cybersecurity requirements imposed on institutions. The cost of entry for users has been lowered by utilizing a web interface providing access to backend portal resources. Users can browse or search for data which they are allowed to see, data reduction applications can be run without having to load the software, sample activation calculations can be performed for SNS and HFIR beamlines, McStas simulations can be run on TeraGrid and ORNL computers, and advanced analysis applications such as those being produced by the DANSE project can be run. Behind the scenes is a live cataloging system which automatically catalogs and archives experiment data via the data management system, and provides proposal team members access

  18. Small Specimen Data from a High Temperature HFIR Irradiation Experiment

    SciTech Connect (OSTI)

    Burchell, Timothy D; McDuffee, Joel Lee; Thoms, Kenneth R

    2014-01-01

    The HTV capsule is a High Flux Isotope Reactor (HFIR) target-rod capsule designed to operate at very high temperatures. The graphite containing section of the capsule (in core) is approximately 18 inches (457.2 mm) long and is separated into eight temperature zones. The specimen diameters within each zone are set to achieve the desired gas gap and hence design temperature (900 C, 1200 C or 1500 C). The capsule has five zones containing 0.400 inch (10.16 mm) diameter specimens, two zones containing 0.350 inch (8.89 mm) diameter specimens and one zone containing 0.300 inch (7.62 mm) diameter specimens. The zones have been distributed within the experiment to optimize the gamma heating from the HFIR core as well as minimize the axial heat flow in the capsule. Consequently, there are two 900 C zones, three 1200 C zones, and three 1500 C zones within the HTV capsule. Each zone contains nine specimens 0.210 0.002 inches (5.334 mm) in length. The capsule will be irradiated to a peak dose of 3.17 displacements per atom. The HTV specimens include samples of the following graphite grades: SGL Carbon s NBG-17 and NBG-18, GrafTech s PCEA, Toyo Tanso s IG-110, Mersen s 2114 and the reference grade H-451 (SGL Carbon). As part of the pre-irradiation program the specimens were characterized using ASTM Standards C559 for bulk density, and ASTM C769 for approximate Young s modulus from the sonic velocity. The probe frequency used for the determination of time of flight of the ultrasonic signal was 2.25 MHz. Marked volume (specimen diameter) effects were noted for both bulk density (increased with increasing specimen volume or diameter) and Dynamic Young s modulus (decreased with increasing specimen volume or diameter). These trends are extended by adding the property vs. diameter data for unirradiated AGC-1 creep specimens (nominally 12.5 mm-diameter x 25.4 mm-length). The relatively large reduction in Dynamic Young s Modulus was surprising given the trend for increasing density

  19. Spallator and APEX nuclear fuel cycle: a new option for nuclear power

    SciTech Connect (OSTI)

    Steinberg, M.

    1982-01-01

    A new nuclear fuel cycle is described which provides a long term supply of nuclear fuel for the thermal LWR nuclear power reactors and eliminates the need for long-term storage of radioactive waste. Fissile fuel is produced by the Spallator which depends on the production of spallation neutrons by the interaction of high-energy (1 to 2 GeV) protons on a heavy-metal target. The neutrons are absorbed in a surrounding natural-uranium or thorium blanket in which fissile Pu-239 to U-233 is produced. Advances in linear accelerator technology makes it possible to design and construct a high-beam-current continuous-wave proton linac for production purposes. The target is similar to a sub-critical reactor and produces heat which is converted to electricity for supplying the linac. The Spallator is a self-sufficient fuel producer, which can compete with the fast breeder. The APEX fuel cycle depends on recycling the transuranics and long-lived fission products while extracting the stable and short-lived fission products when reprocessing the fuel. Transmutation and decay within the fuel cycle and decay of short-lived fission products external to the fuel cycle eliminates the need for long-term geological age shortage of fission-product waste.

  20. The Spallator and APEX nuclear fuel cycle: a new option for nuclear power

    SciTech Connect (OSTI)

    Steinberg, M.

    1983-02-01

    A new nuclear fuel cycle is described which provides a long term supply of nuclear fuel for the thermal LWR nuclear power reactors and eliminates the need for long-term storage of radioactive waste. Fissile fuel is produced by the Spallator which depends on the production of spallation neutrons by the interaction of high energy (1 to 2 GeV) protons on a heavy metal target. The neutrons are absorbed in a surrounding natural uranium or thorium blanket in which fissile Pu-239 or U-233 is produced. Advances in linear accelerator technology makes it possible to design and construct a high beam current continuous wave proton linac for production purposes. The target is similar to a sub-critical reactor and produces heat which is converted to electricity for supplying the linac. The Spallator is a selfsufficient fuel producer, which can compete with the fast breeder. The APEX fuel cycle depends on recycling the transuranics and long-lived fission products while extracting the stable and short-lived fission products when reprocessing the fuel. Transmutation and decay within the fuel cycle and decay of the short-lived fission products external to the fuel cycle eliminates the need for long-term geological age storage of fission product waste.

  1. Ultracold Neutrons at Los Alamos National Laboratory

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

    UCN Facility LANSCE is home to one of the most intense sources of some of the coldest subatomic particles: ultracold neutrons (UCNs). The LANSCE Ultracold Neutron (UCN) source is a unique facility that produces high energy spallation neutrons and uses solid deuterium to cool the neutrons by one million billion-fold. The resulting UCNs have some unique properties that allow them to be studied precisely: they move at speeds of only a few meters per second, and are completely confined by magnetic

  2. Spallation Model for the Titanium-Rich Supernova Remnant Cassiopeia A

    SciTech Connect (OSTI)

    Ouyed, Rachid; Leahy, Denis; Ouyed, Amir; Jaikumar, Prashanth

    2011-10-07

    Titanium-rich subluminous supernovae are rare and challenge current SN nucleosynthesis models. We present a model in which ejecta from a standard supernova is impacted by a second explosion of the neutron star (a quark nova), resulting in spallation reactions that lead to {sup 56}Ni destruction and {sup 44}Ti creation under the right conditions. Basic calculations of the spallation products shows that a delay between the two explosions of {approx}5 days reproduces the observed abundance of {sup 44}Ti in Cas A and explains its low luminosity as a result of the destruction of {sup 56}Ni. Our results could have important implications for light curves of subluminous as well as superluminous supernovae.

  3. New precision measurements of free neutron beta decay with cold neutrons

    SciTech Connect (OSTI)

    Baeßler, Stefan; Bowman, James David; Penttilä, Seppo I.; Počanić, Dinko

    2014-10-14

    Precision measurements in free neutron beta decay serve to determine the coupling constants of beta decay, and offer several stringent tests of the standard model. This study describes the free neutron beta decay program planned for the Fundamental Physics Beamline at the Spallation Neutron Source at Oak Ridge National Laboratory, and finally puts it into the context of other recent and planned measurements of neutron beta decay observables.

  4. Fundamental neutron physics at LANSCE

    SciTech Connect (OSTI)

    Greene, G.

    1995-10-01

    Modern neutron sources and science share a common origin in mid-20th-century scientific investigations concerned with the study of the fundamental interactions between elementary particles. Since the time of that common origin, neutron science and the study of elementary particles have evolved into quite disparate disciplines. The neutron became recognized as a powerful tool for studying condensed matter with modern neutron sources being primarily used (and justified) as tools for neutron scattering and materials science research. The study of elementary particles has, of course, led to the development of rather different tools and is now dominated by activities performed at extremely high energies. Notwithstanding this trend, the study of fundamental interactions using neutrons has continued and remains a vigorous activity at many contemporary neutron sources. This research, like neutron scattering research, has benefited enormously by the development of modern high-flux neutron facilities. Future sources, particularly high-power spallation sources, offer exciting possibilities for continuing this research.

  5. Neutron Production by Muon Spallation I: Theory (Technical Report...

    Office of Scientific and Technical Information (OSTI)

    We describe the physics and codes developed in the Muon Physics Package. This package is a ... Authors: Luu, T ; Hagmann, C Publication Date: 2006-11-13 OSTI Identifier: 900172 Report ...

  6. The Spallation Neutron Source Beam Commissioning and Initial...

    Office of Scientific and Technical Information (OSTI)

    Craig E. 2 ; Dodson, George W. 2 ; Feshenko, A. 5 ; ... James R. 10 ; Purcell, John David 2 ; Shea, T. 11 ; Shishlo, Andrei P 2 ; Sibley, C. 2 ; Stockli, Martin P. ...

  7. Stabilized operation of the improvement of the Spallation Neutron...

    Office of Scientific and Technical Information (OSTI)

    Kay 1 ; Peters, Charles C 1 ; Thompson, David H 1 ; Stockli, Martin P 1 ; Williams, Derrick C 1 + Show Author Affiliations ORNL Publication Date: 2010-01-01 OSTI ...

  8. The Spallation Neutron Source Project | Department of Energy

    Energy Savers [EERE]

    Executive Resources » The Senior Executive Service (SES) The Senior Executive Service (SES) Senior Executive Service (SES) seal The Senior Executive Service (SES) is a corps of men and women who administer public programs at the highest levels of Federal Government utilizing well-honed executive skills and broad perspectives of government and public service. Positions are primarily managerial and supervisory and serve just below top Presidential appointees forming a vital link between these

  9. HEATING DISTRIBUTIONS IN THE TARGET OF THE SPALLATION NEUTRON...

    Office of Scientific and Technical Information (OSTI)

    ... Conj on Math. and Camp., Reactor Physics and Environmental Analysis in Nuclear Applications, American Nuclear Society, Madrid, Spain, Sept 27-30, 1999. Fig. 1. Contour plot of the ...

  10. Neutron Spallation Measurements And Impacts On Low Background Experiments

    SciTech Connect (OSTI)

    Aguayo, Estanislao; Kouzes, Richard T.; Siciliano, Edward R.

    2014-09-01

    Ultra-low background experiments, such as neutrinoless double beta decay, carried out deep underground to escape cosmic ray backgrounds can nonetheless be limited in sensitivity by cosmogenically induced signals. This limit can either be produced directly during operation from cosmic muon events in the detector volume, or can be produced by radioactive decay of cosmogenically generated radionuclides created while the detector materials were above ground. An accurate knowledge of the production of the latter source of background is of paramount importance in order to be able to interpret the results of low-background experiments.

  11. Stripper foil failure modes and cures at the Spallation Neutron...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: SC USDOE - Office of Science (SC) Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; BEAM STRIPPERS; BREAKDOWN; CHARGE ...

  12. Energy Dissipation in the Target Station of the Spallation Neutron...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE Office of Energy Research (ER) Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; 99 MATHEMATICS, COMPUTERS, ...

  13. Evidence of a halo formation mechanism in the Spallation Neutron...

    Office of Scientific and Technical Information (OSTI)

    Publication Date: 2013-04-23 OSTI Identifier: 1091911 Type: Published Article Journal Name: Physical Review Special Topics - Accelerators and Beams Additional Journal Information: ...

  14. Evidence of a halo formation mechanism in the Spallation Neutron...

    Office of Scientific and Technical Information (OSTI)

    Type: Published Article Journal Name: Physical Review Special Topics - Accelerators and ... Export Metadata Endnote Excel CSV XML Save to My Library Send to Email Send to Email ...

  15. High Flux Isotope Reactor cold neutron source reference design concept

    SciTech Connect (OSTI)

    Selby, D.L.; Lucas, A.T.; Hyman, C.R.

    1998-05-01

    In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH{sub 2}) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH{sub 2} cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept.

  16. Surface modification to prevent oxide scale spallation

    DOE Patents [OSTI]

    Stephens, Elizabeth V; Sun, Xin; Liu, Wenning; Stevenson, Jeffry W; Surdoval, Wayne; Khaleel, Mohammad A

    2013-07-16

    A surface modification to prevent oxide scale spallation is disclosed. The surface modification includes a ferritic stainless steel substrate having a modified surface. A cross-section of the modified surface exhibits a periodic morphology. The periodic morphology does not exceed a critical buckling length, which is equivalent to the length of a wave attribute observed in the cross section periodic morphology. The modified surface can be created using at least one of the following processes: shot peening, surface blasting and surface grinding. A coating can be applied to the modified surface.

  17. Intense fusion neutron sources

    SciTech Connect (OSTI)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-15

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 10{sup 15}-10{sup 21} neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 10{sup 20} neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the

  18. Production of radioactive isotopes through cosmic muon spallation in KamLAND

    SciTech Connect (OSTI)

    Abe, S.; Furuno, K.; Gando, Y.; Ikeda, H.; Kibe, Y.; Kishimoto, Y.; Minekawa, Y.; Mitsui, T.; Nakajima, K.; Nakajima, K.; Nakamura, M.; Shimizu, I.; Shimizu, Y.; Shirai, J.; Suekane, F.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Terashima, A.; Watanabe, H.

    2010-02-15

    Radioactive isotopes produced through cosmic muon spallation are a background for rare-event detection in nu detectors, double-beta-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of {sup 11}C. Data from the Kamioka liquid-scintillator antineutrino detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillators, and for checking estimates from current simulations based upon MUSIC, FLUKA, and GEANT4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be Y{sub n}=(2.8+-0.3)x10{sup -4} mu{sup -1} g{sup -1} cm{sup 2}. For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment.

  19. Study of the Production of Radioactive Isotopes through Cosmic Muon Spallation in KamLAND

    SciTech Connect (OSTI)

    KamLAND Collaboration; Abe, S.; Enomoto, S.; Furuno, K.; Gando, Y.; Ikeda, H.; Inoue, K.; Kibe, Y.; Kishimoto, Y.; Koga, M.; Minekawa, Y.; Mitsui, T.; Nakajima, K.; Nakajima, K.; Nakamura, K.; Nakamura, M.; Shimizu, I.; Shimizu, Y.; Shirai, J.; Suekane, F.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Terashima, A.; Watanabe, H.; Yonezawa, E.; Yoshida, S.; Kozlov, A.; Murayama, H.; Busenitz, J.; Classen, T.; Grant, C.; Keefer, G.; Leonard, D. S.; McKee, D.; Piepke, A.; Banks, T. I.; Bloxham, T.; Detwiler, J. A.; Freedman, S. J.; Fujikawa, B. K.; Gray, F.; Guardincerri, E.; Hsu, L.; Ichimura, K.; Kadel, R.; Lendvai, C.; Luk, K.-B.; O'Donnell, T.; Steiner, H. M.; Winslow, L. A.; Dwyer, D. A.; Jillings, C.; Mauger, C.; McKeown, R. D.; Vogel, P.; Zhang, C.; Berger, B. E.; Lane, C. E.; Maricic, J.; Miletic, T.; Batygov, M.; Learned, J. G.; Matsuno, S.; Pakvasa, S.; Foster, J.; Horton-Smith, G. A.; Tang, A.; Dazeley, S.; Downum, K. E.; Gratta, G.; Tolich, K.; Bugg, W.; Efremenko, Y.; Kamyshkov, Y.; Perevozchikov, O.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Heeger, K. M.; Piquemal, F.; Ricol, J.-S.; Decowski, M. P.

    2009-06-30

    Radioactive isotopes produced through cosmic muon spallation are a background for rare event detection in {nu} detectors, double-beta-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of {sup 11}C. Data from the Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillator, and for checking estimates from current simulations based upon MUSIC, FLUKA, and Geant4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be (2.8 {+-} 0.3) x 10{sup -4} n/({mu} {center_dot} (g/cm{sup 2})). For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment.

  20. Waste heat recovery from the European Spallation Source cryogenic helium plants - implications for system design

    SciTech Connect (OSTI)

    Jurns, John M.; Bäck, Harald; Gierow, Martin

    2014-01-29

    The European Spallation Source (ESS) neutron spallation project currently being designed will be built outside of Lund, Sweden. The ESS design includes three helium cryoplants, providing cryogenic cooling for the proton accelerator superconducting cavities, the target neutron source, and for the ESS instrument suite. In total, the cryoplants consume approximately 7 MW of electrical power, and will produce approximately 36 kW of refrigeration at temperatures ranging from 2-16 K. Most of the power consumed by the cryoplants ends up as waste heat, which must be rejected. One hallmark of the ESS design is the goal to recycle waste heat from ESS to the city of Lund district heating system. The design of the cooling system must optimize the delivery of waste heat from ESS to the district heating system and also assure the efficient operation of ESS systems. This report outlines the cooling scheme for the ESS cryoplants, and examines the effect of the cooling system design on cryoplant design, availability and operation.

  1. Neutron Irradiation of Hydrided Cladding Material in HFIR Summary of Initial Activities

    Office of Energy Efficiency and Renewable Energy (EERE)

    Irradiation is known to have a significant impact on the properties and performance of Zircaloy cladding and structural materials (material degradation processes, e.g., effects of hydriding).  This...

  2. Neutron Imaging Developments at LANSCE

    SciTech Connect (OSTI)

    Nelson, Ronald Owen; Hunter, James F.; Schirato, Richard C.; Vogel, Sven C.; Swift, Alicia L.; Ickes, Timothy Lee; Ward, William Carl; Losko, Adrian Simon; Tremsin, Anton; Sevanto, Sanna Annika; Espy, Michelle A.; Dickman, Lee Thoresen; Malone, Michael

    2015-10-29

    Thermal, epithermal, and high-energy neutrons are available from two spallation sources at the 800 MeV proton accelerator. Improvements in detectors and computing have enabled new capabilities that use the pulsed beam properties at LANSCE; these include amorphous Si (aSi) detectors, intensified charge-coupled device cameras, and micro-channel plates. Applications include water flow in living specimens, inclusions and fission products in uranium oxide, and high-energy neutron imaging using an aSi flat panel with ZnS(Ag) scintillator screen. images of a metal/plastic cylinder from photons, low-energy and high-energy neutrons are compared.

  3. SPALLATION STUDIES ON SHOCK LOADED U-6 WT PCT NB.

    SciTech Connect (OSTI)

    D. TONKS; ET AL

    2001-01-10

    Several spallation experiments have been performed on the 6 wt pct alloy of uranium using gas gun driven normal plate impacts with VISAR instrumentation and soft recovery. The nominal shock pressures achieved were 28, 34, 42, 50, 55, and 82 kbar. This paper will focus on spallation modeling, e.g. using the 1 D characteristics code CHARADE to simulate the free surface particle velocity. The spallation model involves the ductile growth and coalescence of voids. Metallographical examination of recovered samples and details of the experimental apparatus are discussed in a separate paper.

  4. Preliminary Assessment of the Impact on Reactor Vessel dpa Rates Due to Installation of a Proposed Low Enriched Uranium (LEU) Core in the High Flux Isotope Reactor (HFIR)

    SciTech Connect (OSTI)

    Daily, Charles R.

    2015-10-01

    An assessment of the impact on the High Flux Isotope Reactor (HFIR) reactor vessel (RV) displacements-per-atom (dpa) rates due to operations with the proposed low enriched uranium (LEU) core described by Ilas and Primm has been performed and is presented herein. The analyses documented herein support the conclusion that conversion of HFIR to low-enriched uranium (LEU) core operations using the LEU core design of Ilas and Primm will have no negative impact on HFIR RV dpa rates. Since its inception, HFIR has been operated with highly enriched uranium (HEU) cores. As part of an effort sponsored by the National Nuclear Security Administration (NNSA), conversion to LEU cores is being considered for future HFIR operations. The HFIR LEU configurations analyzed are consistent with the LEU core models used by Ilas and Primm and the HEU balance-of-plant models used by Risner and Blakeman in the latest analyses performed to support the HFIR materials surveillance program. The Risner and Blakeman analyses, as well as the studies documented herein, are the first to apply the hybrid transport methods available in the Automated Variance reduction Generator (ADVANTG) code to HFIR RV dpa rate calculations. These calculations have been performed on the Oak Ridge National Laboratory (ORNL) Institutional Cluster (OIC) with version 1.60 of the Monte Carlo N-Particle 5 (MCNP5) computer code.

  5. 3D COMSOL Simulations for Thermal Deflection of HFIR Fuel Plate in the "Cheverton-Kelley" Experiments

    SciTech Connect (OSTI)

    Jain, Prashant K; Freels, James D; Cook, David Howard

    2012-08-01

    Three dimensional simulation capabilities are currently being developed at Oak Ridge National Laboratory using COMSOL Multiphysics, a finite element modeling software, to investigate thermal expansion of High Flux Isotope Reactor (HFIR) s low enriched uranium fuel plates. To validate simulations, 3D models have also been developed for the experimental setup used by Cheverton and Kelley in 1968 to investigate the buckling and thermal deflections of HFIR s highly enriched uranium fuel plates. Results for several simulations are presented in this report, and comparisons with the experimental data are provided when data are available. A close agreement between the simulation results and experimental findings demonstrates that the COMSOL simulations are able to capture the thermal expansion physics accurately and that COMSOL could be deployed as a predictive tool for more advanced computations at realistic HFIR conditions to study temperature-induced fuel plate deflection behavior.

  6. International workshop on cold neutron sources

    SciTech Connect (OSTI)

    Russell, G.J.; West, C.D. )

    1991-08-01

    The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5--8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people from seven countries attended. Because the meeting was the first of its kind in over forty years, much time was spent acquainting participants with past and planned activities at reactor and spallation facilities worldwide. As a result, the meeting had more of a conference flavor than one of a workshop. The general topics covered at the workshop included: Criteria for cold source design; neutronic predictions and performance; energy deposition and removal; engineering design, fabrication, and operation; material properties; radiation damage; instrumentation; safety; existing cold sources; and future cold sources.

  7. Neutron Imaging Calibration to Measure Void Fraction

    SciTech Connect (OSTI)

    Geoghegan, Patrick J; Bilheux, Hassina Z; Sharma, Vishaldeep; Fricke, Brian A

    2015-01-01

    Void fraction is an intuitive parameter that describes the fraction of vapor in a two-phase flow. It appears as a key variable in most heat transfer and pressure drop correlations used to design evaporating and condensing heat exchangers, as well as determining charge inventory in refrigeration systems. Void fraction measurement is not straightforward, however, and assumptions on the invasiveness of the measuring technique must be made. Neutron radiography or neutron imaging has the potential to be a truly non-invasive void fraction measuring technique but has until recently only offered qualitative descriptions of two-phase flow, in terms of flow maldistributions, for example. This paper describes the calibration approach necessary to employ neutron imaging to measure steady-state void fraction. Experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA.

  8. Preequilibrium Emission of Light Fragments in Spallation Reactions

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Preequilibrium Emission of Light Fragments in Spallation Reactions Citation Details In-Document Search Title: Preequilibrium Emission of Light Fragments in Spallation Reactions No abstract prepared. Authors: Kerby, Leslie M. [1] ; Mashnik, Stepan G. [1] ; Sierk, Arnold John [1] + Show Author Affiliations Los Alamos National Laboratory Publication Date: 2012-08-17 OSTI Identifier: 1049321 Report Number(s): LA-UR-12-22825 TRN: US1204458 DOE Contract Number:

  9. Ductile-to-brittle transition in spallation of metallic glasses

    SciTech Connect (OSTI)

    Huang, X.; Ling, Z.; Dai, L. H.

    2014-10-14

    In this paper, the spallation behavior of a binary metallic glass Cu{sub 50}Zr{sub 50} is investigated with molecular dynamics simulations. With increasing the impact velocity, micro-voids induced by tensile pulses become smaller and more concentrated. The phenomenon suggests a ductile-to-brittle transition during the spallation process. Further investigation indicates that the transition is controlled by the interaction between void nucleation and growth, which can be regarded as a competition between tension transformation zones (TTZs) and shear transformation zones (STZs) at atomic scale. As impact velocities become higher, the stress amplitude and temperature rise in the spall region increase and micro-structures of the material become more unstable. Therefore, TTZs are prone to activation in metallic glasses, leading to a brittle behavior during the spallation process.

  10. GRAIN-SCALE FAILURE IN THERMAL SPALLATION DRILLING

    SciTech Connect (OSTI)

    Walsh, S C; Lomov, I; Roberts, J J

    2012-01-19

    Geothermal power promises clean, renewable, reliable and potentially widely-available energy, but is limited by high initial capital costs. New drilling technologies are required to make geothermal power financially competitive with other energy sources. One potential solution is offered by Thermal Spallation Drilling (TSD) - a novel drilling technique in which small particles (spalls) are released from the rock surface by rapid heating. While TSD has the potential to improve drilling rates of brittle granitic rocks, the coupled thermomechanical processes involved in TSD are poorly described, making system control and optimization difficult for this drilling technology. In this paper, we discuss results from a new modeling effort investigating thermal spallation drilling. In particular, we describe an explicit model that simulates the grain-scale mechanics of thermal spallation and use this model to examine existing theories concerning spalling mechanisms. We will report how borehole conditions influence spall production, and discuss implications for macro-scale models of drilling systems.

  11. METALLURGICAL CHARACTERIZATION OF ATLAS CYLINDRICALLY CONVERGENT SPALLATION EXPERIMENTS.

    SciTech Connect (OSTI)

    Thissell, W. R.; Cerreta, E. K.; Anderson, W. A.; Atchison, W. A.; Cochrane, J. C.; Kaul, Ann M.; Keinigs, R. K.; Ladish, J. S.; Lindemuth, I. R.; Oro, D. M.; Paisley, D.; G. Rodriguez,; Salazar, M. A.; Stokes, J. L.; Taylor, A. J.; Tonks, D. L.

    2003-07-18

    The microstructural distribution and nature of damage from three different cylindrically convergent spallation experiments performed on the pulsed power machine named Atlas are presented. Longitudinal momentum trapping was used to minimize the influence of release waves and thereby decrease the dimensionality of the experiments. Two of the experiments involved soft capture of the spalled piece. The material used is a proprietary directionally cast Al alloy with a mostly equiaxed grain morphology and essentially random texture in the region of spallation. The damage was most distributed in the lowest impact velocity shot and became progressively more narrow with increasing impact velocity. The effectiveness of the momentum trap design increased with increasing impact velocity.

  12. Shock-induced consolidation and spallation of Cu nanopowders

    SciTech Connect (OSTI)

    Huang, L.; Han, W. Z.; Luo, S. N.; An, Q.; Goddard, W. A. III

    2012-01-01

    A useful synthesis technique, shock synthesis of bulk nanomaterials from nanopowders, is explored here with molecular dynamics simulations. We choose nanoporous Cu ({approx}11 nm in grain size and 6% porosity) as a representative system, and perform consolidation and spallation simulations. The spallation simulations characterize the consolidated nanopowders in terms of spall strength and damage mechanisms. The impactor is full density Cu, and the impact velocity (u{sub i}) ranges from 0.2 to 2 km s{sup -1}. We present detailed analysis of consolidation and spallation processes, including atomic-level structure and wave propagation features. The critical values of u{sub i} are identified for the onset plasticity at the contact points (0.2 km s{sup -1}) and complete void collapse (0.5 km s{sup -1}). Void collapse involves dislocations, lattice rotation, shearing/friction, heating, and microkinetic energy. Plasticity initiated at the contact points and its propagation play a key role in void collapse at low u{sub i}, while the pronounced, grain-wise deformation may contribute as well at high u{sub i}. The grain structure gives rise to nonplanar shock response at nanometer scales. Bulk nanomaterials from ultrafine nanopowders ({approx}10 nm) can be synthesized with shock waves. For spallation, grain boundary (GB) or GB triple junction damage prevails, while we also observe intragranular voids as a result of GB plasticity.

  13. Neutron Scattering of CeNi at the Spallation Neutron Source at...

    Office of Scientific and Technical Information (OSTI)

    Close Cite: Bibtex Format Close 0 pages in this document matching the terms "" Search For Terms: Enter terms in the toolbar above to search the full text of this document for ...

  14. Neutron Scattering of CeNi at the Spallation Neutron Source at...

    Office of Scientific and Technical Information (OSTI)

    APA Chicago Bibtex Export Metadata Endnote Excel CSV XML Save to My Library Send to Email Send to Email Email address: Content: Close Send Cite: MLA Format Close Cite: APA ...

  15. Neutronics Simulations of 237Np Targets to Support Safety-Basis and 238Pu Production Assessment Efforts at the High Flux Isotope Reactor

    SciTech Connect (OSTI)

    Chandler, David; Ellis, Ronald James

    2015-01-01

    Fueled by two highly enriched uranium-bearing fuel elements surrounded by a large concentric ring of beryllium reflector, the High Flux Isotope Reactor (HFIR) provides one of the highest neutron fluxes in the world and is used to produce unique isotopes like plutonium-238. The National Aeronautics and Space Administration use radioisotope thermoelectric generators powered by 238Pu for deep-space missions. As part of the US Department of Energy s task to reestablish the domestic production of 238Pu, a technology demonstration sub-project has been initiated to establish a new 238Pu supply chain. HFIR safety-basis neutronics calculations are being performed to ensure the target irradiations have no adverse impacts on reactor performance and to calculate data required as input to follow-on thermal-structural, thermal-hydraulic and radionuclide/dose analyses. Plutonium-238 production assessments are being performed to estimate the amount of 238Pu that can be produced in HFIR s permanent beryllium reflector. It is estimated that a total of 0.96 1.12 kg 238Pu (~1.28 1.49 kg PuO2 at 85% 238Pu/Pu purity) could be produced per year in HFIR s permanent beryllium reflector irradiation facilities if they are all utilized.

  16. Hybrid superconducting neutron detectors

    SciTech Connect (OSTI)

    Merlo, V.; Lucci, M.; Ottaviani, I.; Salvato, M.; Cirillo, M.; Scherillo, A.; Celentano, G.; Pietropaolo, A.

    2015-03-16

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, {sup 10}B + n → α + {sup 7}Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current I{sub c}, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed.

  17. EPICS V4 Evaluation for SNS Neutron Data

    SciTech Connect (OSTI)

    Kasemir, Kay; Pearson, Matthew R; Guyotte, Greg S

    2015-01-01

    Version 4 of the Experimental Physics and Industrial Control System (EPICS) toolkit allows defining application-specific structured data types (pvData) and offers a network protocol for their efficient exchange (pvAccess). We evaluated V4 for the transport of neutron events from the detectors of the Spallation Neutron Source (SNS) to data acquisition and experiment monitoring systems. This includes the comparison of possible data structures, performance tests, and experience using V4 in production on a beam line.

  18. 11th LANSCE School on Neutron Scattering | Lecturers

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

    Lecturers (Tentative) Lectures are primarily given by outside experts relevant to this year's topic. John Ankner | Oak Ridge National Laboratory John Ankner, Oak Ridge National Laboratory John Ankner is a Senior Research Scientist at the Spallation Neutron Source at Oak Ridge National Laboratory. His research centers on the design, optimization, and application of neutron reflectometers to the study of condensed-matter interfaces. Materials of interest include synthetic polymers, biological and

  19. Cryogenic Neutron Protein Crystallography: routine methods and potential benefits

    SciTech Connect (OSTI)

    Weiss, Kevin L; Tomanicek, Stephen J; NG, Joseph D

    2014-01-01

    The use of cryocooling in neutron diffraction has been hampered by several technical challenges such as the need for specialized equipment and techniques. Recently we have developed and deployed equipment and strategies that allow for routine neutron data collection on cryocooled crystals using off the shelf components. This system has several advantages, compared to a closed displex cooling system such as fast cooling coupled with easier crystal mounting and centering. The ability to routinely collect cryogenic neutron data for analysis will significantly broaden the range of scientific questions that can be examined by neutron protein crystallography. Cryogenic neutron data collection for macromolecules has recently become available at the new Biological Diffractometer BIODIFF at FRM II and the Macromolecular Diffractometer (MaNDi) at the Spallation Neutron Source, Oak Ridge National Laboratory. To evaluate the benefits of a cryocooled neutron structure we collected a full neutron data set on the BIODIFF instrument on a Toho-1 lactamase structure at 100K.

  20. Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fukuda, Makoto; Kiran Kumar, N. A. P.; Koyanagi, Takaaki; Garrison, Lauren M.; Snead, Lance L.; Katoh, Yutai; Hasegawa, Akira

    2016-07-02

    We performed a neutron irradiation to single crystal pure tungsten in the mixed spectrum High Flux Isotope Reactor (HFIR). In order to investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ~90–~800 °C and fast neutron fluences were 0.02–9.00 × 1025 n/m2 (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. Moreover, the hardness and microstructure changes exhibitedmore » a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 1025 n/m2 (E > 0.1 MeV). Finally, irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 1025 n/m2 (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten.« less

  1. HFIR (High Flux Isotope Reactor) pressure vessel and structural components materials surveillance program: Supplement 1

    SciTech Connect (OSTI)

    Cheverton, R.D.; McGinty, D.M.; McWherter, J.R.; Nanstad, R.K.

    1987-10-01

    Extending the life of the HFIR vessel by the proposed 10 effective full-power years is contingent upon a continuation of the materials surveillance program and the application of hydrostatic proof testing. As a part of the surveillance program, Charpy V-notch (CVN) specimens of shell, weld and nozzle materials are installed adjacent to the inner surface of the vessel and are removed periodically for testing to determine the radiation-induced increase in the nil-ductility transition temperature. Hydro testing is conducted to prove that a critical combination of flaw size, stress and fracture toughness does not exist. Information from the materials surveillance program is used in a fracture mechanics analysis to confirm that the hydro-test pressure being applied is appropriate for the desired life extension of the vessel. This report specifies (1) the number, type, location and schedule for removal-testing of the CVN specimens for the continuing materials surveillance program, and (2) the procedures and test conditions for the hydro test.

  2. Search for the Neutron Electric Dipole Moment

    SciTech Connect (OSTI)

    Plaster, Brad

    2010-08-04

    Searches for the neutron electric dipole moment (EDM) are motivated by their highly suppressed Standard Model value. The observation of a non-zero signal in the next generation of experiments would point unambiguously to the existence of new physics beyond the Standard Model. Several ongoing efforts worldwide hold the potential for an up to two-orders-of-magnitude improvement beyond the current upper limit on the neutron EDM of 2.9x10{sup -6} e-cm. In this talk, I review the basic measurement principles of neutron EDM searches, then discuss a new experiment to be carried out in the United States at the Spallation Neutron Source with ultracold neutrons and an in-situ '3He''co-magnetometer'.

  3. Accelerator spallation reactors for breeding of fissile fuel and transmuting fission products. Status and prospects

    SciTech Connect (OSTI)

    Steinberg, M.

    1981-01-01

    This report constitutes a summary review of the status and prospects of the development of accelerator spallation reactors for breeding fissile fuel and for transmuting fission products.

  4. BNL Activities in Advanced Neutron Source Development: Past and Present

    SciTech Connect (OSTI)

    Hastings, J.B.; Ludewig, H.; Montanez, P.; Todosow, M.; Smith, G.C.; Larese, J.Z.

    1998-06-14

    Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In this report we discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.

  5. Analysis of in-situ electrical conductivity data from the HFIR TRIST-ER1 experiment

    SciTech Connect (OSTI)

    Zinkle, S.J.; Snead, L.L.; Shikama, T.

    1997-08-01

    The current vs. applied voltage data generated from the HFIR TRIST-ER1 experiment have been analyzed to determine the electrical conductivity of the 15 aluminum oxide specimens and the MgO-insulated electrical cables as a function of irradiation dose. With the exception of the 0.05%Cr-doped sapphire (ruby) specimen, the electrical conductivity of the alumina specimens remained at the expected radiation induced conductivity (RIC) level of <10{sup -6} S/m during full-power reactor irradiation (10-16 kGy/s) at 450-500{degrees}C up to a maximum dose of {approximately}3 dpa. The ruby specimen showed a rapid initial increase in conductivity to {approximately}2 x 10{sup -4} S/m after {approximately}0.1 dpa, followed by a gradual decrease to <1 x 10{sup -6} S/m after 2 dpa. Nonohmic electrical behavior was observed in all of the specimens, and was attributed to preferential attraction of ionized electrons in the capsule gas to the unshielded low-side bare electrical leads emanating from the subcapsules. The electrical conductivity was determined from the slope of the specimen current vs. voltage curve at negative voltages, where the gas ionization effect was minimized. Dielectric breakdown tests performed on unirradiated mineral-insulated coaxial cables identical to those used in the high voltage coaxial cables during the 3-month irradiation is attributable to thermal dielectric breakdown in the glass seals at the end of the cables, as opposed to a radiation-induced electrical degradation (RIED) effect.

  6. Event-Based Processing of Neutron Scattering Data

    SciTech Connect (OSTI)

    Peterson, Peter F.; Campbell, Stuart I.; Reuter, Michael A.; Taylor, Russell J.; Zikovsky, Janik L.

    2015-09-16

    Many of the world's time-of-flight spallation neutrons sources are migrating to the recording of individual neutron events. This provides for new opportunities in data processing, the least of which is to filter the events based on correlating them with logs of sample environment and other ancillary equipment. This paper will describe techniques for processing neutron scattering data acquired in event mode that preserve event information all the way to a final spectrum, including any necessary corrections or normalizations. This results in smaller final errors, while significantly reducing processing time and memory requirements in typical experiments. Results with traditional histogramming techniques will be shown for comparison.

  7. Simulated Irradiation of Samples in HFIR for use as Possible Test Materials in the MPEX (Material Plasma Exposure Experiment) Facility

    SciTech Connect (OSTI)

    Ellis, Ronald James; Rapp, Juergen

    2014-01-01

    The importance of Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) facility will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. The project presented in this paper involved performing assessments of the induced radioactivity and resulting radiation fields of a variety of potential fusion reactor materials. The scientific code packages MCNP and SCALE were used to simulate irradiation of the samples in HFIR; generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. These state-of-the-art simulation methods were used in addressing the challenge of the MPEX project to minimize the radioactive inventory in the preparation of the samples for inclusion in the MPEX facility.

  8. Production of Medical Radioisotopes in the ORNL High Flux Isotope Reactor (HFIR) for Cancer Treatment and Arterial Restenosis Therapy after PTCA

    DOE R&D Accomplishments [OSTI]

    Knapp, F. F. Jr.; Beets, A. L.; Mirzadeh, S.; Alexander, C. W.; Hobbs, R. L.

    1998-06-01

    The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) represents an important resource for the production of a wide variety of medical radioisotopes. In addition to serving as a key production site for californium-252 and other transuranic elements, important examples of therapeutic radioisotopes which are currently routinely produced in the HFIR for distribution include dysprosium-166 (parent of holmium-166), rhenium-186, tin-117m and tungsten-188 (parent of rhenium-188). The nine hydraulic tube (HT) positions in the central high flux region permit the insertion and removal of targets at any time during the operating cycle and have traditionally represented a major site for production of medical radioisotopes. To increase the irradiation capabilities of the HFIR, special target holders have recently been designed and fabricated which will be installed in the six Peripheral Target Positions (PTP), which are also located in the high flux region. These positions are only accessible during reactor refueling and will be used for long-term irradiations, such as required for the production of tin-117m and tungsten-188. Each of the PTP tubes will be capable of housing a maximum of eight HT targets, thus increasing the total maximum number of HT targets from the current nine, to a total of 57. In this paper the therapeutic use of reactor-produced radioisotopes for bone pain palliation and vascular brachytherapy and the therapeutic medical radioisotope production capabilities of the ORNL HFIR are briefly discussed.

  9. Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; Detweiler, Ryan; Maurer, Richard J.; Mitchell, Stephen E.; Guss, Paul P.; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions ofmore » neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and developed a data acquisition (DAQ) system to collect

  10. 2009 International Conference on Neutron Scattering (ICNS 2009)

    SciTech Connect (OSTI)

    Gopal Rao, PhD; Gillespie, Donna

    2010-08-05

    The ICNS provides a focal point for the worldwide neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as would-be neutron users. The International Conference on Neutron Scattering thus serves a dual role as an international user meeting and a scientific meeting. As a venue for scientific exchange, the ICNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. Each of the major national neutron facilities (NIST, LANSCE, ANL, HFIR and SNS), along with their international counterparts, has an opportunity to exchange information with each other and to update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities.

  11. Mesoscale polycrystal calculations of damage in spallation in metals

    SciTech Connect (OSTI)

    Tonks, Davis L [Los Alamos National Laboratory; Bingert, John F [Los Alamos National Laboratory; Livescu, Veronica [Los Alamos National Laboratory; Luo, Shengnian [Los Alamos National Laboratory; Bronkhorst, C A [Los Alamos National Laboratory

    2010-01-01

    The goal of this project is to produce a damage model for spallation in metals informed by the polycrystalline grain structure at the mesoscale. Earlier damage models addressed the continuwn macroscale in which these effects were averaged out. In this work we focus on cross sections from recovered samples examined with EBSD (electron backscattered diffraction), which reveal crystal grain orientations and voids. We seek to understand the loading histories of specific sample regions by meshing up the crystal grain structure of these regions and simulating the stress, strain, and damage histories in our hydro code, FLAG. The stresses and strain histories are the fundamental drivers of damage and must be calculated. The calculated final damage structures are compared with those from the recovered samples to validate the simulations.

  12. DANCE : a 4[pi] barium fluoride detector for measuring neutron capture on unstable nuclei /.

    SciTech Connect (OSTI)

    Ullmann, J. L.; Haight, Robert C.; Hunt, L. F.; Reifarth, R.; Rundberg, R. S.; Bredeweg, T. A.; Fowler, Malcolm M.; Miller, G. G.; Heil, M.; Käppeler, F.; Chamberlin, E. P.

    2002-01-01

    Measurements of neutron capture on unstable nuclei are important for studies of s-process nucleosynthesis, nuclear waste transmutation, and stewardship science. A 160-element, 4{pi} barium fluoride detector array, and associated neutron flight path, is being constructed to make capture measurements at the moderated neutron spallation source at LANSCE. Measurements can be made on as little as 1 mg of sample material over energies from near thermal to near 100 keV. The design of the DANCE array is described and neutron flux measurements from flight path commissioning are shown. The array is expected to be complete by the end of 2002.

  13. Utilization of the High Flux Isotope Reactor at Oak Ridge National Laboratory

    SciTech Connect (OSTI)

    Selby, Douglas L; Bilheux, Hassina Z; Meilleur, Flora; Jones, Amy; Bailey, William Barton; Vandergriff, David H

    2015-01-01

    This paper addresses several aspects of the scientific utilization of the Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR). Topics to be covered will include: 1) HFIR neutron scattering instruments and the formal instrument user program; 2) Recent upgrades to the neutron scattering instrument stations at the reactor, and 3) eMod a new tool for addressing instrument modifications and providing configuration control and design process for scientific instruments at HFIR and the Spallation Neutron Source (SNS). There are 15 operating neutron instrument stations at HFIR with 12 of them organized into a formal user program. Since the last presentation on HFIR instruments at IGORR we have installed a Single Crystal Quasi-Laue Diffractometer instrument called IMAGINE; and we have made significant upgrades to HFIR neutron scattering instruments including the Cold Triple Axis Instrument, the Wide Angle Neutron Diffractometer, the Powder Diffractometer, and the Neutron Imaging station. In addition, we have initiated upgrades to the Thermal Triple Axis Instrument and the Bio-SANS cold neutron instrument detector system. All of these upgrades are tied to a continuous effort to maintain a high level neutron scattering user program at the HFIR. For the purpose of tracking modifications such as those mentioned and configuration control we have been developing an electronic system for entering instrument modification requests that follows a modification or instrument project through concept development, design, fabrication, installation, and commissioning. This system, which we call eMod, electronically leads the task leader through a series of questions and checklists that then identifies such things as ES&H and radiological issues and then automatically designates specific individuals for the activity review process. The system has been in use for less than a year and we are still working out some of the inefficiencies, but we believe that this will become a very

  14. Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation

    SciTech Connect (OSTI)

    Maziasz, P.J.

    1985-11-01

    This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs.

  15. Rear surface spallation on single-crystal silicon in nanosecond laser micromachining

    SciTech Connect (OSTI)

    Ren, Jun; Orlov, Sergei S.; Hesselink, Lambertus

    2005-05-15

    Rear surface spallation of single-crystal silicon under 5-ns laser pulse ablation at intensities of 0.6-60 GW/cm{sup 2} is studied through postablation examination of the ablated samples. The spallation threshold energy and the spallation depth's dependences on the energy and target thickness are measured. From the linear relation between the spallation threshold energy and the target thickness, an estimation of the material spall strength around 1.4 GPa is obtained, in reasonable agreement with the spall strength estimation of 0.8-1.2 GPa at a strain rate of 10{sup 7} s{sup -1} using Grady's model for brittle materials. The experiment reveals the internal fracturing process over an extended zone in silicon, which is controlled by the competition between the shock pressure load and the laser ablation rate. The qualities of the laser microstructuring and micromachining results are greatly improved by using an acoustic impedance matching approach.

  16. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    commissioning (3) educational facilities (3) neutron diffraction (3) technology assessment (3) education (2) hfir (2) hfir reactor neutron (2) instrumentation related to nuclear ...

  17. Neutron-Irradiated Samples as Test Materials for MPEX

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ellis, Ronald James; Rapp, Juergen

    2015-10-09

    Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of themore » samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.« less

  18. Neutron-Irradiated Samples as Test Materials for MPEX

    SciTech Connect (OSTI)

    Ellis, Ronald James; Rapp, Juergen

    2015-10-09

    Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of the samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.

  19. Radiation transport analyses in support of the SNS Target Station Neutron Beam Line Shutters Title I Design

    SciTech Connect (OSTI)

    Miller, T.M.; Pevey, R.E.; Lillie, R.A.; Johnson, J.O.

    2000-12-01

    A detailed radiation transport analysis of the Spallation Neutron Source (SNS) shutters is important for the construction of the SNS because of its impact on conventional facility design, normal operation of the facility, and maintenance operations. Thus far the analysis of the SNS shutter travel gaps has been completed. This analysis was performed using coupled Monte Carlo and multi-dimensional discrete ordinates calculations.

  20. Neutronic reactor

    DOE Patents [OSTI]

    Wende, Charles W. J.; Babcock, Dale F.; Menegus, Robert L.

    1983-01-01

    A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

  1. Development of an Efficient Approach to Perform Neutronics Simulations for Plutonium-238 Production

    SciTech Connect (OSTI)

    Chandler, David; Ellis, Ronald James

    2016-01-01

    Conversion of 238Pu decay heat into usable electricity is imperative to power National Aeronautics and Space Administration (NASA) deep space exploration missions; however, the current stockpile of 238Pu is diminishing and the quality is less than ideal. In response, the US Department of Energy and NASA have undertaken a program to reestablish a domestic 238Pu production program and a technology demonstration sub-project has been initiated. Neutronics simulations for 238Pu production play a vital role in this project because the results guide reactor safety-basis, target design and optimization, and post-irradiation examination activities. A new, efficient neutronics simulation tool written in Python was developed to evaluate, with the highest fidelity possible with approved tools, the time-dependent nuclide evolution and heat deposition rates in 238Pu production targets irradiated in the High Flux Isotope Reactor (HFIR). The Python Activation and Heat Deposition Script (PAHDS) was developed specifically for experiment analysis in HFIR and couples the MCNP5 and SCALE 6.1.3 software quality assured tools to take advantage of an existing high-fidelity MCNP HFIR model, the most up-to-date ORIGEN code, and the most up-to-date nuclear data. Three cycle simulations were performed with PAHDS implementing ENDF/B-VII.0, ENDF/B-VII.1, and the Hybrid Library GPD-Rev0 cross-section libraries. The 238Pu production results were benchmarked against VESTA-obtained results and the impact of various cross-section libraries on the calculated metrics were assessed.

  2. Value engineering study final report on -- Spallation Neutron Source, Oak Ridge, Tennessee

    SciTech Connect (OSTI)

    1999-01-31

    The SNS Project has had numerous DOE/SC reviews to validate the technical baseline, management approach, cost, schedule, and Conceptual Design Report. As a result, in FY 1999 the SNS received $130 million and approval from Congress to initiate Title 1 design and construction activities. Since this funding was less than requested for FY 1999 ($157 million) and validated in previous reviews, and because of improved costing information, the SNS Project team will reassess the cost and schedule baselines in an upcoming DOE review in January 1999. In preparation for this reassessment, the SNS has initiated a value engineering process to improve the design and to recover cost and contingency. Value engineering will continue throughout the life of the project, but the results described in this report are our initial efforts.

  3. OAK RIDGE NATIONAL LABORATORY SPALLATION NEUTRON SOURCE ELECTRICAL SYSTEMS AVAILABILITY AND IMPROVEMENTS

    SciTech Connect (OSTI)

    Cutler, Roy I; Peplov, Vladimir V; Wezensky, Mark W; Norris, Kevin Paul; Barnett, William E; Hicks, Jim; Weaver, Joey T; Moss, John; Rust, Kenneth R; Mize, Jeffery J; Anderson, David E

    2011-01-01

    SNS electrical systems have been operational for 4 years. System availability statistics and improvements are presented for AC electrical systems, DC and pulsed power supplies and klystron modulators.

  4. Comments on the possibility of cavitation in liquid metal targets for pulsed spallation neutron sources

    SciTech Connect (OSTI)

    Carpenter J.M.

    1996-06-01

    When short pulses of protons strike the volume of a liquid target, the rapid heating produces a pressurized region which relaxes as the pressure wave propagates outward. Skala and Bauer have modeled the effects of the pressure wave impinging on the container walls of a liquid mercury target under ESS conditions. They find that high pressures and high wall stresses result if the medium is uniform, nearly incompressible liquid. The pressure and the stresses are much reduced if the liquid contains bubbles of helium, due to their high compressibility. However, according to the calculation, the pressure still reaches an atmosphere or so at the surface, which reflects the compressive wave as a rarefaction wave of the same magnitude. Even such modest underpressures can lead to the growth of bubbles (cavitation) at or near the surface, which can collapse violently and erode the container surface. It is necessary to avoid this. Leighton provides a wide ranging discussion of pressure waves in bubbly media, which may provide insights into the nature and control of cavitation phenomena. The paper surveys some of the relevant information from that source.

  5. A workshop on enhanced national capability for neutron scattering

    SciTech Connect (OSTI)

    Hurd, Alan J; Rhyne, James J; Lewis, Paul S

    2009-01-01

    This two-day workshop will engage the international neutron scattering community to vet and improve the Lujan Center Strategic Plan 2007-2013 (SP07). Sponsored by the LANL SC Program Office and the University of California, the workshop will be hosted by LANSCE Professor Sunny Sinha (UCSD). Endorsement by the Spallation Neutron Source will be requested. The discussion will focus on the role that the Lujan Center will play in the national neutron scattering landscape assuming full utilization of beamlines, a refurbished LANSCE, and a 1.4-MW SNS. Because the Lujan Strategic Plan is intended to set the stage for the Signature Facility era at LANSCE, there will be some discussion of the long-pulse spallation source at Los Alamos. Breakout groups will cover several new instrument concepts, upgrades to present instruments, expanded sample environment capabilities, and a look to the future. The workshop is in keeping with a request by BES to update the Lujan strategic plan in coordination with the SNS and the broader neutron community. Workshop invitees will be drawn from the LANSCE User Group and a broad cross section of the US, European, and Pacific Rim neutron scattering research communities.

  6. Basic Physics Data: Measurement of Neutron Multiplicity from Induced Fission

    SciTech Connect (OSTI)

    Pozzi, Sara; Haight, Robert

    2015-05-04

    From October 1 to October 17 a team of researchers from UM visited the LANSCE facility for an experiment during beam-time allotted from October 4 to October 17. A total of 24 detectors were used at LANSCE including liquid organic scintillation detectors (EJ-309), NaI scintillation detectors, and Li-6 enriched glass detectors. It is a double time-offlight (TOF) measurement using spallation neutrons generated by a target bombarded with pulsed high-energy protons. The neutrons travel to an LLNL-manufactured parallel plate avalanche chamber (PPAC) loaded with thin U-235 foils in which fission events are induced. The generated fission neutrons and photons are then detected in a detector array designed and built at UM and shipped to LANSCE. Preparations were made at UM, where setup and proposed detectors were tested. The UM equipment was then shipped to LANSCE for use at the 15L beam of the weapons neutron research (WNR) facility.

  7. Search for the Neutron Electric Dipole Moment at the SNS at Oak Ridge

    SciTech Connect (OSTI)

    Kolarkar, Ameya

    2010-02-10

    The possible existence of a non-zero electric dipole moment (EDM) of the neutron is of fundamental interest for our understanding of the nature of electro-weak and strong interactions. The experimental search for this moment has the potential to reveal new sources of T and CP violation and to challenge calculations that propose extensions to the Standard Model. A new experiment being developed at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory seeks to lower the current EDM limit of the neutron by a factor of 50 to 100 over the present upper limit of 2.9x10{sup -26} e cm.

  8. SNS nEDM | Ultracold Neutrons at Los Alamos National Laboratory (pRad)

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

    SNS nEDM An electric dipole moment (EDM) measures the separation of positive and negative charges within a system and is an extremely sensitive probe of physics beyond the standard model. A new neutron EDM (nEDM) experiment is being developed to be installed at the Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, with a goal sensitivity of δdn~5 x10-28 e-cm, an improvement of two orders of magnitude over the current limit set

  9. A radial collimator for a time-of-flight neutron spectrometer

    SciTech Connect (OSTI)

    Stone, M. B.; Abernathy, D. L. [Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Niedziela, J. L.; Loguillo, M. J.; Overbay, M. A. [Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-08-15

    We have engineered and installed a radial collimator for use in the scattered beam of a neutron time-of-flight spectrometer at a spallation neutron source. The radial collimator may be used with both thermal and epithermal neutrons, reducing the detected scattering intensity due to material outside of the sample region substantially. The collimator is located inside of the sample chamber of the instrument, which routinely cycles between atmospheric conditions and cryogenic vacuum. The oscillation and support mechanism of the collimator allow it to be removed from use without breaking vacuum. We describe here the design and characterization of this radial collimator.

  10. 2010 American Conference on Neutron Scattering (ACNS 2010)

    SciTech Connect (OSTI)

    Billinge, Simon

    2011-06-17

    The ACNS provides a focal point for the national neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as “would-be” neutron users. The American Conference on Neutron Scattering thus serves a dual role as a national user meeting and a scientific meeting. As a venue for scientific exchange, the ACNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. As a “super-user” meeting, the ACNS fulfills the main objectives of users' meetings previously held periodically at individual national neutron facilities, with the advantage of a larger and more diverse audience. To this end, each of the major national neutron facilities (NIST, LANSCE, HFIR and SNS) have an opportunity to exchange information and update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities. For many of the national facilities, this super-user meeting should obviate the need for separate user meetings that tax the time, energy and budgets of facility staff and the users alike, at least in years when the ACNS is held. We rely upon strong participation from the national facilities. The NSSA intends that the American Conference on Neutron Scattering (ACNS) will occur approximately every two years, but not in years that coincide with the International or European Conferences on Neutron Scattering. The ACNS is to be held in association with one of the national neutron centers in a rotating sequence, with the host facility providing local organization

  11. Ship Effect Neutron Measurements And Impacts On Low-Background Experiments

    SciTech Connect (OSTI)

    Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Siciliano, Edward R.

    2013-10-01

    The primary particles entering the upper atmosphere as cosmic rays create showers in the atmosphere that include a broad spectrum of secondary neutrons, muons and protons. These cosmic-ray secondaries interact with materials at the surface of the Earth, yielding prompt backgrounds in radiation detection systems, as well as inducing long-lived activities through spallation events, dominated by the higher-energy neutron secondaries. For historical reasons, the multiple neutrons produced in spallation cascade events are referred to as “ship effect” neutrons. Quantifying the background from cosmic ray induced activities is important to low-background experiments, such as neutrino-less double beta decay. Since direct measurements of the effects of shielding on the cosmic-ray neutron spectrum are not available, Monte Carlo modeling is used to compute such effects. However, there are large uncertainties (orders of magnitude) in the possible cross-section libraries and the cosmic-ray neutron spectrum for the energy range needed in such calculations. The measurements reported here were initiated to validate results from Monte Carlo models through experimental measurements in order to provide some confidence in the model results. The results indicate that the models provide the correct trends of neutron production with increasing density, but there is substantial disagreement between the model and experimental results for the lower-density materials of Al, Fe and Cu.

  12. Dissertation: Precompound Emission of Energetic Light Fragments in Spallation Reactions

    SciTech Connect (OSTI)

    Kerby, Leslie Marie

    2015-08-04

    Emission of light fragments (LF) from nuclear reactions is an open question. Different reaction mechanisms contribute to their production; the relative roles of each, and how they change with incident energy, mass number of the target, and the type and emission energy of the fragments is not completely understood. None of the available models are able to accurately predict emission of LF from arbitrary reactions. However, the ability to describe production of LF (especially at energies ≳ 30 MeV) from many reactions is important for different applications, such as cosmic-ray-induced Single Event Upsets (SEUs), radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The Cascade-Exciton Model (CEM) version 03.03 and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) version 03.03 event generators in Monte Carlo N-Particle Transport Code version 6 (MCNP6) describe quite well the spectra of fragments with sizes up to ⁴He across a broad range of target masses and incident energies (up to ~ 5 GeV for CEM and up to ~ 1 TeV/A for LAQGSM). However, they do not predict the high energy tails of LF spectra heavier than ⁴He well. Most LF with energies above several tens of MeV are emitted during the precompound stage of a reaction. The current versions of the CEM and LAQGSM event generators do not account for precompound emission of LF larger than ⁴He. The aim of our work is to extend the precompound model in them to include such processes, leading to an increase of predictive power of LF-production in MCNP6. This entails upgrading the Modified Exciton Model currently used at the preequilibrium stage in CEM and LAQGSM. It also includes expansion and examination of the coalescence and Fermi break-up models used in the precompound stages of spallation reactions within CEM and LAQGSM. Extending our models to include emission of fragments heavier than ⁴He at the precompound stage has indeed provided results that have much

  13. Preparation and Testing of Corrosion and Spallation-Resistant Coatings

    SciTech Connect (OSTI)

    Hurley, John

    2015-11-01

    with the Rene 80. One-inch-diameter buttons were machined from each of the bonded blocks and sent to Siemens for standard oxidation, spallation, and corrosion testing, which should be complete in the spring of 2016.

  14. A Multigroup Library of Neutron and Gamma Cross Sections and Response Functions in the Energy Range up to 800 MeV.

    Energy Science and Technology Software Center (OSTI)

    1987-05-20

    Version 00 The energy range of the library, from thermal to 800 MeV is relevant to the solution of shielding, nuclear heating, and other radiation protection problems connected with the accelerator neutron sources e.g. spallation target. The data contains 10 elements of shielding and biological importance. They can be easily implemented to the neutron transport codes like ANISN and DOT by using the activity option.

  15. Neutron skins and neutron stars

    SciTech Connect (OSTI)

    Piekarewicz, J.

    2013-11-07

    The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ('PREX') at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in {sup 208}Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron beams may impact the physics of neutron stars.

  16. Effect of Substrate Thickness on Oxide Scale Spallation for Solid Oxide Fuel Cells

    SciTech Connect (OSTI)

    Liu, Wenning N.; Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2011-07-01

    In this paper, the effect of the ferritic substrate's thickness on the delamination/spallation of the oxide scale was investigated experimentally and numerically. At the high-temperature oxidation environment of solid oxide fuel cells (SOFCs), a combination of growth stress with thermal stresses may lead to scale delamination/buckling and eventual spallation during SOFC stack cooling, even leading to serious degradation of cell performance. The growth stress is induced by the growth of the oxide scale on the scale/substrate interface, and thermal stress is induced by a mismatch of the coefficient of thermal expansion between the oxide scale and the substrate. The numerical results show that the interfacial shear stresses, which are the driving force of scale delamination between the oxide scale and the ferritic substrate, increase with the growth of the oxide scale and also with the thickness of the ferritic substrate; i.e., the thick ferritic substrate can easily lead to scale delamination and spallation. Experimental observation confirmed the predicted results of the delamination and spallation of the oxide scale on the ferritic substrate.

  17. Neutron guide

    DOE Patents [OSTI]

    Greene, Geoffrey L.

    1999-01-01

    A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

  18. Neutron dosimetry

    DOE Patents [OSTI]

    Quinby, Thomas C.

    1976-07-27

    A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

  19. Event-Based Processing of Neutron Scattering Data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Peterson, Peter F.; Campbell, Stuart I.; Reuter, Michael A.; Taylor, Russell J.; Zikovsky, Janik L.

    2015-09-16

    Many of the world's time-of-flight spallation neutrons sources are migrating to the recording of individual neutron events. This provides for new opportunities in data processing, the least of which is to filter the events based on correlating them with logs of sample environment and other ancillary equipment. This paper will describe techniques for processing neutron scattering data acquired in event mode that preserve event information all the way to a final spectrum, including any necessary corrections or normalizations. This results in smaller final errors, while significantly reducing processing time and memory requirements in typical experiments. Results with traditional histogramming techniquesmore » will be shown for comparison.« less

  20. About UCN | Ultracold Neutrons at Los Alamos National Laboratory

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

    About UCN Ultracold neutrons (UCNs) have extremely low energy, less than 300 neV. At these energies, they are sensitive to magnetic, gravitational, and material potentials that can be realized in a laboratory. UCNs have a temperature of less than 4 mK, move less than 8 m/s, and have a wavelength of more than 500 angstroms. They can be polarized by strong magnetic fields of about 6 Tesla, and are reflected by materials such as Nickel and Copper. The LANSCE UCN source uses spallation to create

  1. Neutron multiplicity measurements with 3He alternative: Straw neutron detectors

    SciTech Connect (OSTI)

    Mukhopadhyay, Sanjoy; Wolff, Ronald; Detwiler, Ryan; Maurer, Richard; Mitchell, Stephen; Guss, Paul; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as ‘‘ship effect ’’) and to the complicated nature of the neutron scattering in that environment. A prototype neutron detector was built using 10B as the converter in a special form factor called ‘‘straws’’ that would address the above problems by looking into the details of multiplicity distributions of neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and

  2. Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

    SciTech Connect (OSTI)

    Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; Detweiler, Ryan; Maurer, Richard J.; Mitchell, Stephen E.; Guss, Paul P.; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions of neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics

  3. Diamond detector for high rate monitors of fast neutrons beams

    SciTech Connect (OSTI)

    Giacomelli, L.; Rebai, M.; Cippo, E. Perelli; Tardocchi, M.; Fazzi, A.; Andreani, C.; Pietropaolo, A.; Frost, C. D.; Rhodes, N.; Schooneveld, E.; Gorini, G.

    2012-06-19

    A fast neutron detection system suitable for high rate measurements is presented. The detector is based on a commercial high purity single crystal diamond (SDD) coupled to a fast digital data acquisition system. The detector was tested at the ISIS pulsed spallation neutron source. The SDD event signal was digitized at 1 GHz to reconstruct the deposited energy (pulse amplitude) and neutron arrival time; the event time of flight (ToF) was obtained relative to the recorded proton beam signal t{sub 0}. Fast acquisition is needed since the peak count rate is very high ({approx}800 kHz) due to the pulsed structure of the neutron beam. Measurements at ISIS indicate that three characteristics regions exist in the biparametric spectrum: i) background gamma events of low pulse amplitudes; ii) low pulse amplitude neutron events in the energy range E{sub dep}= 1.5-7 MeV ascribed to neutron elastic scattering on {sup 12}C; iii) large pulse amplitude neutron events with E{sub n} < 7 MeV ascribed to {sup 12}C(n,{alpha}){sup 9}Be and 12C(n,n')3{alpha}.

  4. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; et al

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section dσ/dΩ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component)more » using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.« less

  5. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    SciTech Connect (OSTI)

    Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Greene, G. L.; Hamblen, J.; Hayes, C.; Kucuker, S.; Mahurin, R.; Maldonado-Velázquez, M.; Martin, E.; McCrea, M.; Mueller, P. E.; Musgrave, M.; Nann, H.; Penttilä, S. I.; Snow, W. M.; Tang, Z.; Wilburn, W. S.

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section dσ/dΩ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.

  6. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    SciTech Connect (OSTI)

    Grammer, K. B.; Alarcon, R.; Barrn-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Greene, G. L.; Hamblen, J.; Hayes, C.; Kucuker, S.; Mahurin, R.; Maldonado-Velzquez, M.; Martin, E.; McCrea, M.; Mueller, P. E.; Musgrave, M.; Nann, H.; Penttil, S. I.; Snow, W. M.; Tang, Z.; Wilburn, W. S.

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section d?/d? from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.

  7. Neutron detector

    DOE Patents [OSTI]

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  8. Note: Versatile sample stick for neutron scattering experiments in high electric fields

    SciTech Connect (OSTI)

    Bartkowiak, M., E-mail: marek.bartkowiak@psi.ch [Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); White, J. S. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen (Switzerland) [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Laboratory for Quantum Magnetism, Ecole Polytechnique Fdrale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Rnnow, H. M.; Pra, K. [Laboratory for Quantum Magnetism, Ecole Polytechnique Fdrale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)] [Laboratory for Quantum Magnetism, Ecole Polytechnique Fdrale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2014-02-15

    We present a versatile high voltage sample stick that fits into all cryomagnets and standard cryostats at the Swiss Spallation Neutron Source, Paul Scherrer Institut, and which provides a low effort route to neutron scattering experiments that combine electric field with low temperature and magnetic field. The stick allows for voltages up to 5 kV and can be easily adapted for different scattering geometries. We discuss the design consideration and thermal behavior of the stick, and give one example to showcase the abilities of the device.

  9. Ultracold neutrons

    SciTech Connect (OSTI)

    Saunders, Alexander

    2015-06-22

    This series of slides describes ultracold neutrons (UCN) and their properties, various UCN sources, and an overview of UCN-based experiments. Numerous diagrams and photographs are included.

  10. Nanoscale Laser-Induced Spallation in SiO2 Films Containing Gold Nanoparticles

    SciTech Connect (OSTI)

    Kudryashov, S.I.; Allen, S.D.; Papernov, S.; Schmid, A.W.

    2006-02-16

    A phenomenological theory of ultraviolet pulsed-laser-induced spallation is proposed to interpret crater formation in SiO2 thin films containing absorbing 18.5-nm gold particles. The theory considers a spherical thermoacoustic stress wave propagating from a thermal source produced by laser-energy absorption inside the particle and surrounding ionized volume. Calculations show that the tensile stress associated with such an acoustic wave may exceed the local strength of the material and cause fracture and spallation of the top film portion. The theory provides an explanation of the experimentally observed complex (two-cone) shape of craters formed in the film with particle-lodging depth exceeding 110 nm. Theoretical estimates for the threshold stress amplitude and peak temperature in the thermal source are in qualitative agreement with the experimental observations.

  11. Negative pressures and spallation in water drops subjected to nanosecond shock waves

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Stan, Claudiu A.; Willmott, Philip R.; Stone, Howard A.; Koglin, Jason E.; Liang, Mengning; Aquila, Andrew L.; Robinson, Joseph S.; Gumerlock, Karl L.; Blaj, Gabriel; Sierra, Raymond G.; et al

    2016-05-16

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below –100 MPamore » were reached in the drops. As a result, we model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.« less

  12. Charlton, L.A.; Difilippo, F.C. 43 PARTICLE ACCELERATORS; 99...

    Office of Scientific and Technical Information (OSTI)

    43 PARTICLE ACCELERATORS; 99 MATHEMATICS, COMPUTERS, INFORMATION SCIENCE, MANAGEMENT, LAW, MISCELLANEOUS; Spallation; Spallation; Neutron Sources; Neutron Sources; Target...

  13. NON-DESTRUCTIVE THERMAL BARRIER COATING SPALLATION PREDICTION BY A LOADBASED MICRO-INDENTATION TECHNIQUE

    SciTech Connect (OSTI)

    J. M. Tannenbaum; K. Lee; B. S.-J. Kang; M.A. Alvin

    2010-11-18

    Currently, the durability and life cycle of thermal barrier coatings (TBC) applied to gas turbine blades and combustor components are limiting the maximum temperature and subsequent efficiency at which gas turbine engines operate. The development of new materials, coating technologies and evaluation techniques is required if enhanced efficiency is to be achieved. Of the current ceramic coating materials used in gas turbine engines, yttria stabilized zirconia (YSZ) is most prevalent, its low thermal conductivity, high thermal expansion coefficient and outstanding mechanical strength make it ideal for use in TBC systems. However, residual stresses caused by coefficients of thermal expansion mismatches within the TBC system and unstable thermally grown oxides are considered the primary causes for its premature and erratic spallation failure. Through finite element simulations, it is shown that the residual stresses generated within the thermally grown oxide (TGO), bond coat (BC), YSZ and their interfaces create slight variations in indentation unloading surface stiffness response prior to spallation failure. In this research, seven air plasma sprayed and one electron beam physical vapor deposition yttria partially stabilized zirconia TBCs were subjected to isothermal and cyclic loadings at 1100C. The associated coating degradation was evaluated using a non-destructive multiple partial unloading micro-indentation procedure. The results show that the proposed non-destructive micro-indentation evaluation technique can be an effective and specimenindependent TBC failure prediction tool capable of determining the location of initial spallation failure prior to its actual occurrence.

  14. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  15. Neutronic reactor

    DOE Patents [OSTI]

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  16. Neutron source

    DOE Patents [OSTI]

    Cason, J.L. Jr.; Shaw, C.B.

    1975-10-21

    A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.

  17. Neutron tubes

    DOE Patents [OSTI]

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  18. HFIR Plant Maintenance - August

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

    6-000 CASL Program Highlights April 2015 Jess C. Gehin Oak Ridge National Laboratory April 30, 2015 CASL-U-2015-0236-000 * VERA Core Simulator (VERA-CS) perform simulation of ...

  19. Method of using deuterium-cluster foils for an intense pulsed neutron source

    DOE Patents [OSTI]

    Miley, George H.; Yang, Xiaoling

    2013-09-03

    A method is provided for producing neutrons, comprising: providing a converter foil comprising deuterium clusters; focusing a laser on the foil with power and energy sufficient to cause deuteron ions to separate from the foil; and striking a surface of a target with the deuteron ions from the converter foil with energy sufficient to cause neutron production by a reaction selected from the group consisting of D-D fusion, D-T fusion, D-metal nuclear spallation, and p-metal. A further method is provided for assembling a plurality of target assemblies for a target injector to be used in the previously mentioned manner. A further method is provided for producing neutrons, comprising: splitting a laser beam into a first beam and a second beam; striking a first surface of a target with the first beam, and an opposite second surface of the target with the second beam with energy sufficient to cause neutron production.

  20. Thermal neutron detection system

    DOE Patents [OSTI]

    Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

    2000-01-01

    According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

  1. NEUTRONIC REACTORS

    DOE Patents [OSTI]

    Wigner, E.P.

    1960-11-22

    A nuclear reactor is described wherein horizontal rods of thermal- neutron-fissionable material are disposed in a body of heavy water and extend through and are supported by spaced parallel walls of graphite.

  2. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  3. Real-Time Active Cosmic Neutron Background Reduction Methods

    SciTech Connect (OSTI)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray-induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  4. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  5. NEUTRON SOURCES

    DOE Patents [OSTI]

    Richmond, J.L.; Wells, C.E.

    1963-01-15

    A neutron source is obtained without employing any separate beryllia receptacle, as was formerly required. The new method is safer and faster, and affords a source with both improved yield and symmetry of neutron emission. A Be container is used to hold and react with Pu. This container has a thin isolating layer that does not obstruct the desired Pu--Be reaction and obviates procedures previously employed to disassemble and remove a beryllia receptacle. (AEC)

  6. Neutron range spectrometer

    DOE Patents [OSTI]

    Manglos, S.H.

    1988-03-10

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

  7. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Hurwitz, H. Jr.; Brooks, H.; Mannal, C.; Payne, J.H.; Luebke, E.A.

    1959-03-24

    A reactor of the heterogeneous, liquid cooled type is described. This reactor is comprised of a central region of a plurality of vertically disposed elongated tubes surrounded by a region of moderator material. The central region is comprised of a central core surrounded by a reflector region which is surrounded by a fast neutron absorber region, which in turn is surrounded by a slow neutron absorber region. Liquid sodium is used as the primary coolant and circulates through the core which contains the fuel elements. Control of the reactor is accomplished by varying the ability of the reflector region to reflect neutrons back into the core of the reactor. For this purpose the reflector is comprised of moderator and control elements having varying effects on reactivity, the control elements being arranged and actuated by groups to give regulation, shim, and safety control.

  8. Prompt Neutron Multiplicity Measurements with Portable Detectors

    SciTech Connect (OSTI)

    S. Mukhopadhyay, R. Wolff, R. Maurer, S. Mitchell, E. X. Smith, P. Guss, J. L. Lacy, L. Sun, A. Athanasiades

    2011-09-01

    Mobile detection of kilogram quantities of special nuclear materials (SNM) during maritime transportation is a challenging problem for the U.S. Department of Homeland Security. Counting neutrons emitted by the SNM and partitioning them from background neutrons of multiple origins is the most effective passive means of detecting the SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment is complex due to the presence of spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. This work studied the possibilities of building a prototype neutron detector using boron- 10 (10B) as the converter in a novel form factor called “straws” that would address the above problem by examining multiplicity distributions of neutrons originating from a fissioning source. Currently, commercially manufactured fission meters (FM) are available that separate cosmic neutrons from non-cosmic neutrons and quantitatively determine the strength of a fissioning source; however, these FMs use 3He, which is becoming increasingly difficult to procure; also the size and weight of a commercial FM is not conducive to manual neutron detection operations in a maritime environment. The current project may provide a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to the FM. The prototype detector provides a large-area, efficient, lightweight, more granular neutron responsive detection surface (to facilitate imaging) to ease the application of the new FMs. A novel prototype fission meter is being designed at National Security Technologies, LLC, using a thin uniform coating of 10B as neutron converter (only 1 micron thick) inside a large array of thin (4 mm diameter) copper tubes. The copper tubes are only 2-mil thick, and each holds the stretched anode wire under tension and high voltage. The tubes are filled with

  9. MCViNE- An object oriented Monte Carlo neutron ray tracing simulation package

    SciTech Connect (OSTI)

    Lin, J. Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry L.; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2015-11-28

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. As a result, with simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.

  10. MCViNE- An object oriented Monte Carlo neutron ray tracing simulation package

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lin, J. Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry L.; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2015-11-28

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiplemore » scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. As a result, with simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.« less

  11. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Fermi, E.; Szilard, L.

    1957-09-24

    Reactors of the type employing plates of natural uranium in a moderator are discussed wherein the plates are um-formly disposed in parallel relationship to each other thereby separating the moderator material into distinct and individual layers. Each plate has an uninterrupted sunface area substantially equal to the cross-sectional area of the active portion of the reactor, the particular size of the plates and the volume ratio of moderator to uranium required to sustain a chain reaction being determinable from the known purity of these materials and other characteristics such as the predictable neutron losses due to the formation of radioactive elements of extremely high neutron capture cross section.

  12. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  13. OPERATIONAL RESULTS OF THE SPALLATION NEUTRON SOURCE (SNS) POLYPHASE CONVERTER-MODULATOR FOR THE 140 KV KLYSTRON RF SYSTEMS

    SciTech Connect (OSTI)

    W.A. REASS; J.D. DOSS; ET AL

    2001-06-01

    This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. Pulse-Width Modulation (PWM) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. Reviews of these design parameters and an examination of the first operational results will be performed.

  14. NEUTRONIC REACTORS

    DOE Patents [OSTI]

    Anderson, H.L.

    1958-10-01

    The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

  15. Neutronic reactor

    DOE Patents [OSTI]

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  16. Liquid lithium target as a high intensity, high energy neutron source

    DOE Patents [OSTI]

    Parkin, Don M.; Dudey, Norman D.

    1976-01-01

    This invention provides a target jet for charged particles. In one embodiment the charged particles are high energy deuterons that bombard the target jet to produce high intensity, high energy neutrons. To this end, deuterons in a vacuum container bombard an endlessly circulating, free-falling, sheet-shaped, copiously flowing, liquid lithium jet that gushes by gravity from a rectangular cross-section vent on the inside of the container means to form a moving web in contact with the inside wall of the vacuum container. The neutrons are produced via break-up of the beam in the target by stripping, spallation and compound nuclear reactions in which the projectiles (deuterons) interact with the target (Li) to produce excited nuclei, which then "boil off" or evaporate a neutron.

  17. Methods for absorbing neutrons

    DOE Patents [OSTI]

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  18. Neutron reflecting supermirror structure

    DOE Patents [OSTI]

    Wood, James L.

    1992-01-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

  19. Neutron reflecting supermirror structure

    DOE Patents [OSTI]

    Wood, J.L.

    1992-12-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

  20. Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Andreani, C.; Anderson, I. S.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C. -K.; Senesi, R.

    2014-12-24

    In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10²more » MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.« less

  1. Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

    SciTech Connect (OSTI)

    Andreani, C.; Anderson, I. S.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C. -K.; Senesi, R.

    2014-12-24

    In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10² MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.

  2. NEUTRONIC REACTORS

    DOE Patents [OSTI]

    Vernon, H.C.

    1959-01-13

    A neutronic reactor of the heterogeneous, fluid cooled tvpe is described. The reactor is comprised of a pressure vessel containing the moderator and a plurality of vertically disposed channels extending in spaced relationship through the moderator. Fissionable fuel material is placed within the channels in spaced relationship thereto to permit circulation of the coolant fluid. Separate means are provided for cooling the moderator and for circulating a fluid coolant thru the channel elements to cool the fuel material.

  3. Spallation process with simultaneous multi-particle emission in nuclear evaporation

    SciTech Connect (OSTI)

    Santos, B. M.

    2013-05-06

    High energy probes have been used currently to explore nuclear reaction mechanism and nuclear structure. The spallation process governs the reaction process around 1 GeV energy regime. A new aspect introduced here to describe the nuclear reaction is the in-medium nucleonnucleon collision framework. The nucleon-nucleon scattering is kinematically treated by using an effective mass to represent the nuclear binding. In respect to the evaporation phase of the reaction, we introduce the simultaneous particles emission decay. This process becomes important due to the rise of new channels at high excitation energy regime of the compound nucleus. As results, the particles yields in the rapid and evaporation phases are obtained and compared to experimental data. The effect and relevance of these simultaneous emission processes in the evaporation chain is also discussed.

  4. Solutions for implementing time-of-flight techniques in low-angle neutron scattering, as realized on the Low-Q Diffractometer at Los Alamos

    SciTech Connect (OSTI)

    Hjelm, R.P. Jr.; Seeger, P.A.

    1992-12-01

    The implementation of small-angle (Low-momentum transfer) neutron scattering at pulsed spallation sources, using time of flight methods, has meant the introduction of some new ideas in instrument design, data acquisition, data reduction and computer management of the experiment and the data. Here we recount some of the salient aspects of solutions for implementing time of fight small-angle neutron scattering instruments at pulsed sources, as realized on the Low-Q Diffractometer, LQD, at Los Alamos. We consider, fortlier, some of the problems that are yet to be solved, and take a short excursion into the future of SANS instrumentation at pulsed sources.

  5. The use of neutron scattering in nuclear weapons research

    SciTech Connect (OSTI)

    Juzaitis, R.J.

    1995-10-01

    We had a weapons science breakout session last week. Although it would have been better to hold it closer in time to this workshop, I think that it was very valuable. it may have been less of a {open_quotes}short-sleeve{close_quotes} workshop environment than we would have liked, but as the first time two communities-the weapons community and the neutron scattering community- got together, it was a wonderful opportunity to transfer information during the 24 presentations that were made. This report contains discussions on the fundamental analysis of documentation of the enduring stockpile; LANSCE`s contribution to weapons; spallation is critical to understanding; weapons safety assessments; applied nuclear physics requires cross section information; fission models need refinement; and establishing teams on collaborative projects.

  6. SHARP Neutronics Expanded

    Broader source: Energy.gov [DOE]

    The SHARP neutronics module, PROTEUS, includes neutron and gamma transport solvers and cross-section processing tools as well as the capability for depletion and fuel cycle analysis.

  7. NEUTRON COUNTER

    DOE Patents [OSTI]

    Curtis, C.D.; Carlson, R.L.; Tubinis, M.P.

    1958-07-29

    An ionization chamber instrument is described for cylindrical electrodes with an ionizing gag filling the channber. The inner electrode is held in place by a hermetic insulating seal at one end of the outer electrode, the other end of the outer electrode being closed by a gas filling tube. The outer surface of the inner electrode is coated with an active material which is responsive to neutron bombardment, such as uranium235 or boron-10, to produce ionizing radiations in the gas. The transverse cross sectional area of the inner electrode is small in relation to that of the channber whereby substantially all of the radiations are directed toward the outer electrode.

  8. NEUTRON SOURCE

    DOE Patents [OSTI]

    Reardon, W.A.; Lennox, D.H.; Nobles, R.G.

    1959-01-13

    A neutron source of the antimony--beryllium type is presented. The source is comprised of a solid mass of beryllium having a cylindrical recess extending therein and a cylinder containing antimony-124 slidably disposed within the cylindrical recess. The antimony cylinder is encased in aluminum. A berylliunn plug is removably inserted in the open end of the cylindrical recess to completely enclose the antimony cylinder in bsryllium. The plug and antimony cylinder are each provided with a stud on their upper ends to facilitate handling remotely.

  9. Pulsed neutrons: one year of experience with the new source at Argonne National Laboratory

    SciTech Connect (OSTI)

    Lander, G.H.

    1982-01-01

    The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a spallation neutron source based on a 500-MeV proton accelerator operating at 30 Hz and with an average proton current of approx. 10 ..mu..A. Neutron-scattering instruments for elastic scattering include two powder diffractometers, a single-crystal diffractometer based on the Laue method and employing a large (30 x 30 cm) position-sensitive scintillation detector, a small-angle diffractometer using a position-sensitive detector, and a polarized-neutron diffractometer which will utilize the spin-refrigerator device to obtain a beam of white polarized neutrons. For inelastic scattering, we presently have the crystal-analyzer spectrometer and two chopper spectrometers capable of providing monoenergetic incident neutron beams of between 100 and 600 MeV. From its inception IPNS has been operating in a user mode and the selection of experiments is made by a Program Committee twice a year on the basis of the scientific merit of submitted proposals.

  10. Neutron Capture Cross Sections for the Re/Os Clock

    SciTech Connect (OSTI)

    Mosconi, M.; Heil, M.; Kaeppeler, F.; Plag, R.; Voss, F.; Wisshak, K.; Mengoni, A.; Cennini, P.; Chiaveri, E.; Ferrari, A.; Fitzpatrick, L.; Herrera-Martinez, A.; Kadi, Y.; Sarchiapone, L.; Vlachoudis, V.; Wendler, H.; Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W.

    2005-05-24

    The radioactive decay of 187Re {yields} 187Os (t1/2 = 43 Gyr) is suited for dating the onset of heavy-element nucleosynthesis. The radiogenic contribution to the 187Os abundance is the difference between the natural abundance and the corresponding s-process component. This component can be obtained via the well-established {sigma}N systematics using the neighboring s-only isotope 186Os, provided the neutron-capture cross sections of both isotopes are known with sufficient accuracy. We report on a new set of experiments performed with a C6D6 detector array at the n{sub T}OF neutron spallation facility of CERN. The capture cross sections of 186Os, 187Os, and 188Os have been measured in the neutron-energy range between 1 eV and 1 MeV, and Maxwellian-averaged cross sections were deduced for the relevant thermal energies from kT=5 keV to 100 keV.