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Nuclear astrophysics at the Holifield Radioactive Ion Beam Facility

Description: The potential for understanding spectacular stellar explosions such as novae, supernovae, and X-ray bursts will be greatly enhanced by the availability of the low-energy, high-intensity, accelerated beams of proton-rich radioactive nuclei currently being developed at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. These beams will be utilized in absolute cross section measurements of crucial (p, {gamma}) capture reactions in efforts to resolve the substantial qualitative uncertainties in current models of explosive stellar hydrogen burning outbursts. Details of the nuclear astrophysics research program with the unique HRIBF radioactive beams and a dedicated experimental endstation--centered on the Daresbury Recoil Separator--will be presented.
Date: December 31, 1994
Creator: Smith, M.S.
Partner: UNT Libraries Government Documents Department

Nuclear astrophysics and the Daresbury Recoil Separator at the Holifield Radioactive Ion Beam Facility

Description: The Daresbury Recoil Separator (DRS) has been installed for nuclear astrophysics research at Oak Ridge National Laboratory`s Holifield Radioactive Ion Beam Facility. It will be used for direct measurements of capture reactions on radioactive ions which occur in stellar explosions such as novae, supernovae and X-ray bursts. These measurements will be made in inverse kinematics with radioactive heavy ion beams incident on hydrogen and helium targets, and the DRS will separate the capture reaction recoils from the intense flux of beam particles. Details of the new DRS experimental equipment and preliminary results from the first commissioning experiments with stable beams are described, along with the plans for the first measurements with radioactive beams. Other astrophysics research efforts at ORNL--in theoretical astrophysics, nuclear astrophysics data evaluation, heavy element nucleosynthesis, theoretical atomic astrophysics, and atomic astrophysics data--are also briefly described.
Date: December 1, 1997
Creator: Smith, M.S.
Partner: UNT Libraries Government Documents Department

US nuclear reaction data program in support of basic research

Description: Information about the US Nuclear Reaction Data Network (USNRDN) such as its members, work in progress, summaries of meetings, and organizational details may be found in its WWW Homepage. This paper is an overview of the data support provided by the network for basic research in nuclear astrophysics, radioactive ion beams, high energy heavy-ion and electron interactions and related activities involving all aspects of data stewardship.
Date: June 1997
Creator: Bhat, M.R.; Chadwick, M. B. & Smith, M. S.
Partner: UNT Libraries Government Documents Department

U.S. nuclear reaction data program in support of basic research

Description: Information about the US Nuclear Reaction Data Network (USNRDN) such as its members, work in progress, summaries of meetings, and organizational details may be found in its WWW Homepage. This paper is an overview of the data support provided by the network for basic research in nuclear astrophysics, radioactive ion beams, high energy heavy ion and electron interactions and related activities involving all aspects of data stewardship.
Date: March 1, 1998
Creator: Bhat, M.R.; Chadwick, M.B. & Smith, M.S.
Partner: UNT Libraries Government Documents Department

Commissioning of the Daresbury Recoil Separator for nuclear astrophysics measurements at the Holifield Radioactive Ion Beam Facility

Description: The Daresbury Recoil Separator (DRS) has been installed for nuclear astrophysics research at Oak Ridge National Laboratory`s Holifield Radioactive Ion Beam Facility. it will be used for direct measurements of capture reactions on radioactive ions which occur in stellar explosions such as novae and X-ray bursts. The physics motivation and plans for the first measurements with radioactive beams are described, and details of the new DRS experimental equipment and preliminary results from the first commissioning experiments with stable beams are given.
Date: December 1, 1997
Creator: Smith, M. S.; Blackmon, J. C. & Koehler, P. E.
Partner: UNT Libraries Government Documents Department

(Centralized reliability data organization for liquid metal reactor components)

Description: The Centralized Reliability Data Organization is a data bank and data analysis center, focusing on reliability, availability, and maintainability (RAM) data for components (e.g., valves, pumps, etc.) operating in liquid metal reactors and test facilities. PNC staff are using the CREDO data base as a resource for their development of a probabilistic safety assessment (PSA) for the MONJU fast breeder reactor now under construction. The meeting was held to discuss: (a) progress in FY 1989, (b) resolution of data base deficiencies and inconsistencies, (c) clarification of definitions for failure mode and failure cause, (d) component boundary definitions, (e) goals and objectives for the remainder of the fiscal year, and (f) proposals for future work. General agreement was reached on the need for improvements to the data base: resolution of data deficiencies and inconsistencies, reduction of the number of failure modes and causes, inclusion of failure severity, and a specific delineation of the boundary for each of the generic components. A schedule will be provided to PNC by 1 March 1991 addressing these issues. A proposal to develop a hybrid mainframe/PC reliability data base to improve user access was declined. A second proposal to develop a reliability data base for PNC's nuclear fuel reprocessing facilities was met with a request for more information. A formal proposal will be forwarded to PNC in the near future.
Date: February 7, 1991
Creator: Smith, M.S. & Manneschmidt, J.F.
Partner: UNT Libraries Government Documents Department

Accident assessment: role of the containment radiation monitor

Description: The containment radiation monitor may provide information to a power reactor operator that can aid assessment of the degree of core damage following a loss-of-coolant accident (LOCA). This paper reports calculations of the exposure rates that would exist in the containment of a commercial pressurized water reactor (PWR) following severe reactor transients. The results indicate exposure rates of 1 to 2 R . h/sup -1/ 30 minutes after a large LOCA, 4 to 5 x 10 R . h/sup -1/ one hour following a release of the gap activity, and 4 . 10/sup 6/ R . h/sup -1/ two hours after a transient that resulted in a fuel melt. Furthermore, differences between the energy spectra of photons released by noble gases and halogens suggest that containment radiation monitors may be designed to differentiate between these radioelements. The calculated exposure rates are not in agreement with the response of containment radiation monitors during the incident at the Crystal River Reactor. Inhomogeneous source terms, the operation of containment building systems, and inaccuracies in release estimates, measurements and calculations may have contributed to this discrepancy in one degree or another.
Date: January 1, 1980
Creator: Desrosiers, A. E.; Scherpelz, R. I.; Smith, M. S. & Grimes, B. K.
Partner: UNT Libraries Government Documents Department

Deterministic transport calculations of dose profiles due to proton beam irradiation

Description: Charged-particle transport calculations are most often carried out using the Monte Carlo technique. For example, the TIGER and EGS codes are used for electron transport calculations, while HETC models the transport of protons and heavy ions. In recent years there has been considerable progress in deterministic models of electron transport. Many of these models are also applicable to protons. In this paper we present discrete ordinates solutions to the Spencer-Lewis equation for protons. In its present form, our code calculates the energy deposition profile and primary proton flux in x-y geometry due to proton beam irradiation. Proton energies up to 0.4 GeV are permissible.
Date: January 1, 1988
Creator: Filippone, W.L.; Smith, M.S.; Santoro, R.T.; Gabriel, T.A. & Alsmiller, R.G. Jr.
Partner: UNT Libraries Government Documents Department

Application of the MASH v1.0 Code System to radiological warfare radiation threats

Description: Nuclear hardening capabilities of US and foreign ground force systems is a primary concern of the Department of Defense (DoD) and US Army. The Monte Carlo Adjoint Shielding Code System -- MASH v1.0 was developed at Oak Ridge National Laboratory (ORNL) to analyze these capabilities, i.e. the shielding effectiveness, for prompt radiation from a nuclear weapon detonation. Rapidly changing world events and the proliferation of nuclear weapons related technology have increased the kinds of nuclear threats to include intentionally dispersed radiation sources and fallout from tactical nuclear weapons used in the modern AirLand battlefield scenario. Consequently, a DoD area of increasing interest focuses on determining the shielding effectiveness of foreign and US armored vehicles to radiological warfare and fallout radiation threats. To demonstrate the applicability of MASH for analyzing dispersed radiation source problems, calculations have been completed for two distributed sources; a dispersed radiation environment simulated by a uniformly distributed {sup 60}Co source, and a {sup 235}U fission weapon fallout source. Fluence and dose assessments were performed for the free-field, the inside of a steel-walled two-meter box, in a phantom standing in the free-field, and in a phantom standing in the two-meter box. The results indicate substantial radiation protection factors for the {sup 60}Co dispersed radiation source and the fallout source compared to the prompt radiation protection factors. The dose protection factors ranged from 40 to 95 for the two-meter box and from 55 to 123 for the mid-gut position of the phantom standing in the box. The results further indicate that a {sup 60}Co source might be a good first order approximation for a tactical fission weapon fallout protection factor analysis.
Date: March 1, 1994
Creator: Johnson, J. O.; Santoro, R. T. & Smith, M. S.
Partner: UNT Libraries Government Documents Department

Motor-operated globe valve performance in a liquid sodium environment

Description: This study investigates motor-operated globe valve (MOV) performance in a liquid sodium environment as reported to the Centralized Reliability Data Organization (CREDO) from site representatives at several liquid metal reactors and liquid metal test facilities. The CREDO data base contains engineering histories for 179 motor-operated glove valves. Thirty nine failures have been documented for these components in over 8.7 million hours of operation. The most common MOV events were anomalies with the limit and torque switches, although human initiated problems were also frequent causes of failures. The failure data suggest that an improved preventive maintenance program with a higher frequency of inspection of the limit and torque switches should increase MOV availability and reliability. The event rate for all failure modes was computed as 4.47 events per 10{sup 8} operating hours by assuming a Poisson distribution of failure over valve operating time. The 5% and 95% confidence limits based on a chi-squared ({chi}{sup 2}) probability distribution function were computed as 3.36 and 5.83 events per 10{sup 6} operating hours, respectively. The operating performance of these liquid metal MOVs was compared to similar data for MOVs in commercial light water reactors and was found to exhibit similar failure rates.
Date: June 1, 1992
Creator: Wood, D. H.; Smith, M. S. & Drischler, J. D.
Partner: UNT Libraries Government Documents Department

Nuclear astrophysics data at ORNL

Description: There is a new program of evaluation and dissemination of nuclear data of critical importance for nuclear astrophysics within the Physics Division of Oak Ridge National Laboratory. Recent activities include determining the rates of the important {sup 14}O({alpha},p){sup 17} F and {sup 17}F(p,{gamma}) {sup 18}Ne reactions, disseminating the Caughlan and Fowler reaction rate compilation on the World Wide Web, and evaluating the {sup 17}O(p,{alpha}){sup 14}N reaction rate. These projects, which are closely coupled to current ORNL nuclear astrophysics research, are briefly discussed along with future plans.
Date: November 1, 1998
Creator: Smith, M.S.; Blackmon, J.C.; Bardayan, D.W. & Ma, Z.
Partner: UNT Libraries Government Documents Department

Three-dimensional discrete ordinates radiation transport calculations of neutron fluxes for beginning-of-cycle at several pressure vessel surveillance positions in the high flux isotope reactor

Description: The objective of this research was to determine improved thermal, epithermal, and fast fluxes and several responses at mechanical test surveillance location keys 2, 4, 5, and 7 of the pressure vessel of the Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) for the beginning of the fuel cycle. The purpose of the research was to provide essential flux data in support of radiation embrittlement studies of the pressure vessel shell and beam tubes at some of the important locations.
Date: November 1, 1993
Creator: Pace, J. V. III; Slater, C. O. & Smith, M. S.
Partner: UNT Libraries Government Documents Department

First on-line results for As and F beams from HRIBF target/ion sources

Description: The first on-line tests of the ion sources to provide radioactive ion beams of {sup 69,70}As and {sup 17,18}F for the Holifield Radioactive Ion Beam Facility (HRIBF) have been performed using the UNISOR facility at HRIBF. The target/ion source is an electron beam plasma (EBP) source similar to the ISOLDE design. The measured efficiencies for {sup 69}As and {sup 70}AS were 0.5 {+-} 0.2% and 0.8 {+-} 0.3%, respectively. The arsenic hold-up time in the tested target ion source was 3.6 {+-} 0.3 hours as measured with {sup 72}As at a target temperature of 1300 {degrees}C. The measured efficiencies for {sup 17}F and {sup 18}F were 0.0052 {+-} 0.0008% and 0.06 {+-} 0.02%, respectively. The source hold-up time for fluorine was measured with Al{sup 18}F since 88% of the observed radioactive fluorine was found in this molecule. The Al{sup 18}F hold-up time was 16.4 {+-} 0.8 minutes at a target temperature of 1470 {degrees}C.
Date: December 31, 1996
Creator: Stracener, D.W.; Carter, H.K.; Kormicki, J.; Breitenbach, J.B.; Blackmon, J.C.; Smith, M.S. et al.
Partner: UNT Libraries Government Documents Department

New neutron capture and transmission measurements for {sup 134,136}Ba at ORELA and their impact on s-process nucleosynthesis calculations

Description: We have made high-resolution neutron capture and transmission measurements on isotopically enriched samples of {sup 134}Ba and {sup 136}Ba at the Oak Ridge Electron Linear Accelerator (ORELA) in the energy range from 20 eV to 500 keV. Previous measurements had a lower energy limit of 3 - 5 keV, which is too high to determine accurately the Maxwellian-averaged capture cross section at the low temperatures (kT {approx} 6 - 12 keV) favored by the most recent stellar models of the {ital s}-process. Our results for the astrophysical reaction rates are in good agreement with the most recent previous measurement at the classical {ital s}-process temperature, kT = 30 keV, but show significant differences at lower 40 temperatures. We discuss the astrophysical implications of these differences.
Date: October 1, 1996
Creator: Koehler, P.E.; Spencer, R.R.; Winters, R.R.; Guber, K.H.; Harvey, J.A.; Hill, N.W. et al.
Partner: UNT Libraries Government Documents Department

First on-line results for As and F beams from HRIBF target/ion sources

Description: The first on-line tests of the ion sources to provide radioactive ion beams of {sup 69,70}As and {sup 17,18}F for the Holifield Radioactive Ion Beam Facility have been performed using the UNISOR facility at HRIBF. For {sup 70}As the measured efficiency is 0.8 {+-} 0.3% with a hold-up time of 3.6 {+-} 0.3 hours as measured with {sup 72}As at a target temperature of 1,270 C. For {sup 17}F the efficiency for Al{sup 17}F is 0.0024 {+-} 0.0008% with a hold-up time of 16.4 {+-} 0.8 m as measured with Al{sup 18}F at a target temperature of 1,470 C.
Date: December 31, 1996
Creator: Carter, H.K.; Kormicki, J.; Stracener, D.W.; Breitenbach, J.B.; Blackmon, J.C.; Smith, M.S. et al.
Partner: UNT Libraries Government Documents Department

Nuclear Data Project Evaluation Activity Report

Description: This report summarizes the activities of the ORNL Nuclear Data Project since the IAEA Advisory Group meeting in October 1996. The group's future plans are also included.
Date: December 14, 1998
Creator: Akovali, Y.A.; Artna-Cohen, A.; Blackmon, J.C.; Radford, D.; Smith, M.S. & Yu, C.-H.
Partner: UNT Libraries Government Documents Department

Recent Nuclear Astrophysics Data Activities in the US

Description: Measurements in nuclear physics laboratories form the empirical foundation for new, realistic, sophisticated theoretical models of a wide variety of astrophysical systems. The predictive power of these models has, in many instances, a strong dependence on the input nuclear data, and more extensive and accurate nuclear data is required for these models than ever before. Progress in astrophysics can be aided by providing scientists with more usable, accurate, and significant amounts of nuclear data in a timely fashion in formats that can be easily incorporated into their models. A number of recent data compilations, evaluations, calculations, and disseminations that address nuclear astrophysics data needs will be described.
Date: August 30, 1999
Creator: Bardayan, D.W.; Blackmon, J.C.; Browne, E.; Firestone, R.B.; Hale, G.M.; Hoffman, R.D. et al.
Partner: UNT Libraries Government Documents Department