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Processing needs and constraints: neutron data processing

Description: New applications for processed data and increased accuracy requirements have generated needs for change in the Evaluated Nuclear Data Files (ENDF). Some constraints must be removed to allow this growth to take place, but other strong constraints must remain to protect existing users.
Date: January 1, 1980
Creator: MacFarlane, R.E.
Partner: UNT Libraries Government Documents Department

Charge exchange probes of nuclear structure and interactions with emphasis on (p,n)

Description: New results from (p,n) studies at IUCF show that it is possible to observe Gamow-Teller (GT) strength and extract GT matrix elements from (p,n) measurements. The charge exchange reactions (/sup 6/Li,/sup 6/He) and (..pi../sup +/,..pi../sup 0/) involve different projectile quantum numbers, and the relationships of these reactions to (p,n) is discussed.
Date: January 1, 1980
Creator: Goodman, C.D.
Partner: UNT Libraries Government Documents Department

150-m measurement of 0. 880- to 100. 0-keV neutron transmissions through four samples of /sup 238/U

Description: In order to study the /sup 238/U + n total cross section, neutron transmissions through 0.076-, 0.254-, 1.080-, and 3.620-cm-thick samples of isotopically enriched /sup 238/U have been measured from 0.880 to 100.0 keV using a time-of-flight technique over a path length of 150 meters with the ORELA pulsed source and a 13-mm-thick Li-glass detector. The measurement is described in detail and both a listing and figures of the resulting transmissions are given. An absolute energy scale accurate to 2 parts in 10,000 was established.
Date: October 1, 1977
Creator: Olsen, D. K.; de Saussure, G.; Perez, R. B.; Difilippo, F. C.; Ingle, R. W. & Weaver, H.
Partner: UNT Libraries Government Documents Department

Analysis of neutron data in the resonance region via the computer code SAMMY

Description: Procedures for analysis of resonance neutron cross-section data have been implemented in a state-of-the-art computer code SAMMY, developed at the Oak Ridge Electron Linear Accelerator (ORELA) at Oak Ridge National Laboratory. A unique feature of SAMMY is the use of Bayes' equations to determine ''best'' values of parameters, which permits sequential analysis of data sets (or subsets) while giving the same results as would be given by a simultaneous analysis. Another important feature is the inclusion of data-reduction parameters in the fitting procedure. Other features of SAMMY are also described.
Date: January 1, 1985
Creator: Larson, N.M.
Partner: UNT Libraries Government Documents Department

Consistency of differential and integral thermonuclear neutronics data

Description: To increase the accuracy of the neutronics analysis of nuclear reactors, physicists and engineers have employed a variety of techniques, including the adjustment of multigroup differential data to improve consistency with integral data. Of the various adjustment strategies, a generalized least-squares procedure which adjusts the combined differential and integral data can significantly improve the accuracy of neutronics calculations compared to calculations employing only differential data. This investigation analyzes 14 MeV neutron-driven integral experiments, using a more extensively developed methodology and a newly developed computer code, to extend the domain of adjustment from the energy range of fission reactors to the energy range of fusion reactors.
Date: January 1, 1978
Creator: Reupke, W.A.
Partner: UNT Libraries Government Documents Department

Use of R-matrix methods for light element evaluations

Description: Some general aspects of parameterizing nuclear reaction data with a unitary, multichannel theory are discussed. The special case of R-matrix theory are discussed. The special case of R-matrix theory is considered, where the explicit separation of long- and short-range forces and the natural occurrence of energy pole terms afford a number of advantages in describing data for light-element reactions. Examples are given for both neutron- and charged-particle-induced reactions which illustrate multichannel R-matrix techniques, including the use of charge symmetry to relate data for mirror systems. The limitations of conventional R-matrix methods are discussed briefly.
Date: January 1, 1980
Creator: Hale, G.M.
Partner: UNT Libraries Government Documents Department

Nuclear data and related services

Description: National Nuclear Data Center (NNDC) maintains a number of data bases containing bibliographic information and evaluated as well as experimental nuclear properties. An evaluated computer file maintained by the NNDC, called the Evaluated Nuclear Structure Data File (ENSDF), contains nuclear structure information for all known nuclides. The ENSDF is the source for the journal ''Nuclear Data Sheets'' which is produced and edited by NNDC. The Evaluated Nuclear Data File (ENDF), on the other hand is designed for storage and retrieval of such evaluated nuclear data as are used in neutronic, photonic, and decay heat calculations in a large variety of applications. Some of the publications from these data bases are the Nuclear Wallet Cards, Radioactivity Handbook, and books on neutron cross sections and resonance parameters. In addition, the NNDC maintains three bibliographic files: NSR - for nuclear structure and decay data related references, CINDA - a bibliographic file for neutron induced reactions, and CPBIB - for charged particle reactions. Selected retrievals from evaluated data and bibliographic files are possible on-line or on request from NNDC. 6 refs., 1 fig.
Date: January 1, 1985
Creator: Tuli, J.K.
Partner: UNT Libraries Government Documents Department

Energy-averaged neutron cross sections of fast-reactor structural materials

Description: The status of energy-averaged cross sections of fast-reactor structural materials is outlined with emphasis on U.S. data programs in the neutron-energy range 1-10 MeV. Areas of outstanding accomplishment and significant uncertainty are noted with recommendations for future efforts. Attention is primarily given to the main constituents of stainless steel (e.g., Fe, Ni, and Cr) and, secondarily, to alternate structural materials (e.g., V, Ti, Nb, Mo, Zr). Generally, the mass regions of interest are A approximately 50 to 60 and A approximately 90 to 100. Neutron total and elastic-scattering cross sections are discussed with the implication on the non-elastic-cross sections. Cross sections governing discrete-inelastic-neutron-energy transfers are examined in detail. Cross sections for the reactions (n;p), (n;n',p), (n;..cap alpha..), (n;n',..cap alpha..) and (n;2n') are reviewed in the context of fast-reactor performance and/or diagnostics. The primary orientation of the discussion is experimental with some additional attention to the applications of theory, the problems of evaluation and the data sensitivity of representative fast-reactor systems.
Date: February 1, 1978
Creator: Smith, A.; McKnight, R. & Smith, D.
Partner: UNT Libraries Government Documents Department

ACDOS1: a computer code to calculate dose rates from neutron activation of neutral beamlines and other fusion-reactor components

Description: A computer code has been written to calculate neutron induced activation of neutral-beam injector components and the corresponding dose rates as a function of geometry, component composition, and time after shutdown. The code, ACDOS1, was written in FORTRAN IV to calculate both activity and dose rates for up to 30 target nuclides and 50 neutron groups. Sufficient versatility has also been incorporated into the code to make it applicable to a variety of general activation problems due to neutrons of energy less than 20 MeV.
Date: August 1, 1981
Creator: Keney, G.S.
Partner: UNT Libraries Government Documents Department

ENDF/B summary documentation

Description: This publication provides a localized source of descriptions for the evaluations contained in the ENDF/B Library. The summary documentation presented is intended to be a more detailed description than the (File 1) comments contained in the computer readable data files, but not so detailed as the formal reports describing each ENDF/B evaluation. The summary documentations were written by the CSEWB (Cross Section Evaluation Working Group) evaluators and compiled by NNDC (National Nuclear Data Center). This edition includes documentation for materials found on ENDF/B Version V tapes 501 to 516 (General Purpose File) excluding tape 504. ENDF/B-V also includes tapes containing partial evaluations for the Special Purpose Actinide (521, 522), Dosimetry (531), Activation (532), Gas Production (533), and Fission Product (541-546) files. The materials found on these tapes are documented elsewhere. Some of the evaluation descriptions in this report contain cross sections or energy level information. (RWR)
Date: July 1, 1979
Creator: Kinsey, R. (comp.)
Partner: UNT Libraries Government Documents Department

Compilation of requests for nuclear data

Description: The purpose of this compilation is to summarize the current needs of US Nuclear Energy programs and other applied technologies for nuclear data. At the present time needs fall primarily in the area of neutron cross sections, although no such limitation is intended. This request list is ordered by target nucleus (isotope) and then reaction type (quantity). An attempt is made to describe the quantity in standard notation. A glossary of these symbols with a short explanatory text is provided. All requests must give the energy (or range of energy) for the incident particle when appropriate. The accuracy needed in percent is also given. The error quoted is assumed to be 1 sigma at each measured point in the energy range requested unless a comment specifies otherwise. (RWR)
Date: April 1, 1979
Partner: UNT Libraries Government Documents Department

Report to the DOE Nuclear Data Committee, 1984

Description: Experimental results are discussed for: /sup 6/ /sup 7/Li(n,/sup 4/He) cross sections at 14 MeV, neutron elastic and inelastic scattering from carbon near 14 MeV, neutron capture cross sections for /sup 46/Ca and /sup 48/Ca at stellar temperatures, revised neutron cross sections for /sup 142/ /sup 143/ /sup 144/Nd, fragment angular distribution for neutron fission of /sup 232/Th, neutron differential scattering measurements in the actinide region, nuclear structure of /sup 244/Am, conversion coefficients of the M4 transition in /sup 193m/Ir, gamma-ray and conversion-electron decay of the /sup 238/U shape isomer, and levels of /sup 244/Cm populated by the beta decay of 10-hr /sup 244g/Am and 26-minute /sup 244m/Am. Calculations described include tests of microscopic optical models for neutron and proton scattering on light nuclei in the range 14 to 45 MeV, a new dynamic model for fission, and the necessity of discrete-level modeling in isomer ratio calculations for neutron-induced reactions on deformed nuclei. Also, a reevaluation for ENDL of sigma(n,f) and anti nu p for /sup 235/U and /sup 239/Pu from 100 keV to 20 MeV is described. 31 references. (WHK)
Date: February 1, 1984
Creator: Wong, C.; Haight, R.C. & Struble, G.L.
Partner: UNT Libraries Government Documents Department

Some nuclear data needs in astrophysics

Description: In this paper we discuss a number of astrophysical environments and how improved nuclear data could facilitate a better understanding of them. One area of interest includes proton and alpha-particle reactions with unstable nuclei which are necessary for understanding the nucleosynthesis and energy generation in hot hydrogen-burning environments. Efforts underway at LLNL and elsewhere to develop the technology for the measurement of these reaction rates are discussed. Heavy-element nucleosynthesis in the late stages of red-giant stars and supernovae requires a complete network of neutron capture rates and beta-decay rates for nuclei near and far from stability. Experimental and theoretical efforts at LLNL to supply the input data and to model the nucleosynthetic environments will be outlined. Suggestions are made as to which nuclear data are most critical for the various scenarios. 42 refs., 11 figs., 1 tab.
Date: May 1, 1985
Creator: Mathews, G.J.; Bauer, R.W.; Bloom, S.D.; Haight, R.C.; Howard, W.M.; Takahashi, K. et al.
Partner: UNT Libraries Government Documents Department

Shielding of fusion reactors

Description: The blanket and shield assemblies of fusion reactors will contain a significant number of very sizable penetrations (neutral beam injection ducts, pumping ports, etc.). The combination of high-energy neutrons and large penetrations will introduce severe design problems that are quite different from those encountered previously. Fusion reactors with their penetrations are very complex geometric structures and in calculating nuclear effects (heating, activation, etc.) tradeoffs must be made between computing efficiency and the accuracy in the geometric modeling. The types of problems that arise due to large penetrations will be illustrated by the calculations that have been carried out to aid in the design of the shielding for the neutral beam injectors of the Tokamak Fusion Test Reactor being built at Princeton University.
Date: January 1, 1979
Creator: Alsmiller, R.G. Jr.
Partner: UNT Libraries Government Documents Department

Some comments on resolution and the analysis and interpretation of experimental results from differential neutron measurements

Description: Effects of finite resolution in differential neutron measurements are examined. General procedures for deriving the experimental resolution functions from a knowledge of the experimental parameters are presented. Problems encountered in the comparison of different data sets, when the measured cross section is known to fluctuate with energy, are discussed. The objective is to encourage closer attention to the matter of resolution by experimenters, evaluators and users of neutron nuclear data.
Date: November 1, 1979
Creator: Smith, D.L.
Partner: UNT Libraries Government Documents Department

Neutron strength functions: the link between resolved resonances and the optical model

Description: Neutron strength functions and scattering radii are useful as energy and channel radius independent parameters that characterize neutron scattering resonances and provide a connection between R-matrix resonance analysis and the optical model. The choice of R-matrix channel radii is discussed, as are limitations on the accuracies of strength functions. New definitions of the p-wave strength function and scattering radius are proposed. For light nuclei, where strength functions display optical model energy variations over the resolved resonances, a doubly reduced partial neutron width is introduced for more meaningful statistical analyses of widths. The systematic behavior of strength functions and scattering radii is discussed.
Date: January 1, 1980
Creator: Moldauer, P.A.
Partner: UNT Libraries Government Documents Department

Simultaneous evaluation of interrelated cross sections by generalized least-squares and related data file requirements

Description: Though several cross sections have been designated as standards, they are not basic units and are interrelated by ratio measurements. Moreover, as such interactions as /sup 6/Li + n and /sup 10/B + n involve only two and three cross sections respectively, total cross section data become useful for the evaluation process. The problem can be resolved by a simultaneous evaluation of the available absolute and shape data for cross sections, ratios, sums, and average cross sections by generalized least-squares. A data file is required for such evaluation which contains the originally measured quantities and their uncertainty components. Establishing such a file is a substantial task because data were frequently reported as absolute cross sections where ratios were measured without sufficient information on which reference cross section and which normalization were utilized. Reporting of uncertainties is often missing or incomplete. The requirements for data reporting will be discussed.
Date: October 25, 1984
Creator: Poenitz, W.P.
Partner: UNT Libraries Government Documents Department

Importance of shield design in minimizing radioactive-material inventory in tokamaks

Description: An optimization study is carried out for the outboard bulk shielding of the STARFIRE reactor. The optimization criteria used include: (1) reactor accessibility shortly after shutdown; (2) minimization of high-level long-term induced activation; and (3) radiation protection of reactor components. It is shown that with a 1.1 m-thick shield, the biological dose inside the reactor room decreases to approx. 1.5 mrem/h within 24 h after shutdown. It is also shown that more than 90% of the total mass of the radioactive material inventory in STARFIRE has a high potential for recycling within 30 to 50 yr after component replacement or reactor decommissioning.
Date: January 1, 1980
Creator: Jung, J. & Abdou, M.
Partner: UNT Libraries Government Documents Department

University of Minnesota progress report No. 4215

Description: Medium-energy nuclear physics research at the University of Minnesota is reviewed. The following studies were undertaken: HRS development; /sup 58/ /sup 60/ /sup 62/ /sup 64/Ni(p,p') at 800 MeV; proton scattering on 2s-1d-shell nuclei; search for orbit flip states in /sup 90/Zr, /sup 120/Sn, /sup 144/Sm, and /sup 208/Pb; large-angle A/sup 116/ /sup 124/Sn, /sup 208/Pb elastic scattering; proton scattering from heavy deformed nuclei; unnatural-parity states in /sup 6/Li, /sup 10/B, /sup 12/C, /sup 14/N, and /sup 28/Si; microscopic form factor calculations - force studies; DEC PDP 11/60 computer; theoretical analysis computer programs; inelastic electron scattering on /sup 90/Zr; and EPICS programs. Three of the above topics, with significant amounts of data, are indexed separately. 40 figures, 1 table. (RWR)
Date: January 1, 1979
Creator: Hintz, N.M.
Partner: UNT Libraries Government Documents Department

Neutron scattering studies in the actinide region

Description: During the report period we have investigated the following areas: Neutron elastic and inelastic scattering measurements on {sup 14}N, {sup 181}Ta, {sup 232}Th, {sup 238}U and {sup 239}Pu; Prompt fission spectra for {sup 232}Th, {sup 235}U, {sup 238}U and {sup 239}Pu; Theoretical studies of neutron scattering; Neutron filters; New detector systems; and Upgrading of neutron target assembly, data acquisition system, and accelerator/beam-line apparatus.
Date: August 1, 1991
Creator: Beghian, L.E. & Kegel, G.H.R.
Partner: UNT Libraries Government Documents Department

ACDOS2: a code for neutron-induced activities and dose rates

Description: In order to anticipate problems from the radioactivation of neutral beam sources as a result of testing, a code has been developed which calculates both the radioactivities produced and the dose rates resulting therefrom. The code ACDOS2 requires neutron source strength and spectral distribution as input, or alternately, the source strength can be calculated internally from an input of neutral beam source parameters. A variety of simple geometries can be specified, and up to 12 times of interest following the shutdown of the neutron source. Radiation attenuating and daughter radioactivities are treated accurately. ACDOS2 is also of use for neutron-induced radioactivation problems involving accelerators, fusion reactors, or fission reactors.
Date: October 1, 1981
Creator: Ruby, L.; Keney, G.S. & Lagache, J.C.
Partner: UNT Libraries Government Documents Department