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Integrated system for production of neutronics and photonics calculational constants. Volume 11. Experimental data, indexes, and techniques of obtaining a selected set of neutron resonance parameters

Description: A tabulation is presented of 52,000 experimental resonance parameters, together with appropriate indexes and bibliographic citations. These materials were contained in the LLL Experimental Neutron Cross Section Library as of May 1, 1972. Techniques used to obtain a selected set of resolved and unresolved resonance parameters from the compilation are described. (auth)
Date: May 1, 1972
Creator: Gyulassy, M.; Howerton, R.J. & Perkins, S.T.
Partner: UNT Libraries Government Documents Department

Development and status of the Evaluated Nuclear Data File ENDF/B

Description: From IAEA conference on physics of fast reactors; Tokyo, Japan (16 Oct 1973). The Evaluated Nuclear Data File is part of a system developed by the USAEC to improve the quality and facilitate the use of nuclear data in applications. The widespread use of a single, welldefined format reduces the number of schemes necessary to process information or compare alternate data sets. A network of checking codes that examine the consistency of the data sets and perform physical checks against known nuclear properties helps to ensure the reliability of the file. The basic elements of the ENDF system are described, and the organization and purposes of the Cross Section Evaluation Working Group (CSEWG) are discussed. (7 figures) (RWR)
Date: January 1, 1973
Creator: Pearlstein, S.
Partner: UNT Libraries Government Documents Department

Remarks on the theory of fast neutron sputtering

Description: From surface effects in controlled thermonuclear fusion devices and reactors meetirg; Argonne, Illinois, USA (10 Jan 1974). Theoretical estimates of neutron sputtering yields are in serious disagreement with experiment, unlike the situation with ion sputtering. Possible reasons for the discrepancy are sought without success. It is shown that chunk ejection by neutrons is not due to single neutron events nor to the dynamic interference of cascades. The need for more complete experimental data to guide development of the theory is emphasized. (auth)
Date: January 1, 1974
Creator: Robinson, M.T.
Partner: UNT Libraries Government Documents Department

Standard thermal energy group structure for generation of thermal group constants from ENDF/B data

Description: The final specifications of a standard energy group structure for the generation of thermal group constants from ENDF/B data are presented. The report represents the work of a committee appointed by the Codes and Formats Subcommittee of the Cross Section Evaluation Working Group and is a parallel effort to work being done in the epithermal energy range. The thermal energy group structure specified in this report was accepted November 10, 1972, by the Cross Section Evaluation Working Group as the standard for generation of thermal group constants from ENDF/B data. The standard thermal group structure specified in this report is consistent with past design experience and thermal spectrum codes, and incorporates specific features for effects known to be important in nuclear design applications in the thermal energy range. Specific recommendations are made as to methods to be used for generation of thermal group constants. (auth)
Date: March 1, 1974
Creator: Finch, D.R.
Partner: UNT Libraries Government Documents Department

Coarse-mesh rebalance methods compatible with the spherical harmonic fictitious source in neutron transport calculations

Description: The coarse-mesh rebalance method, based on neutron conservation, is used in discrete ordinates neutron transport codes to accelerate convergence of the within-group scattering source. Though very powerful for this application, the method is ineffective in accelerating the iteration on the discrete-ordinates-to- spherical-harmonics fictitious sources used for ray-effect elimination. This is largely because this source makes a minimum contribution to the neutron balance equation. The traditional rebalance approach is derived in a variational framework and compared with new rebalance approaches tailored to be compatible with the fictitious source. The new approaches are compared numerically to determine their relative advantages. It is concluded that there is little incentive to use the new methods. (3 tables, 5 figures) (auth)
Date: October 1, 1975
Creator: Miller, W.F. Jr.
Partner: UNT Libraries Government Documents Department

Lawrence Livermore Laboratory Evaluated Nuclear Data Library (ENDL) translated into the ENDF/B format

Description: The LLL Evaluated Nuclear Data Library (ENDL) was translated into the ENDF/B Format. This translation is for the convenience of those people who wish to use the ENDL data, but whose main familiarity is with the ENDF/B formats and procedures. Only the portion of ENDL which deals with neutioninduced interactions (including photon production from neutroninduced reactions) was translated. Those parts of the ENDL library which deal with charged-particle- induced reactions were not translated, since they cannot be accommodated within the ENDF/B system. In order to provide a basis ior judging the validity of the ENDL data calculations were made of the output neutron time spectra from the LLL pulsed-sphere experiments, by using for the calculations both the ENDL cross sections and the ENDF/B-III cross sections. Comparisons between these two sets of calculations and the experimental output neutron time spectra provide a basis for judging the relative merits of the ENDL and ENDF-/B-III data sets in the 5 to 20 MeV neutronenergy regime. (auth)
Date: October 1, 1973
Creator: Howerton, R. J.
Partner: UNT Libraries Government Documents Department

Analysis of neutron scattering and gamma-ray production integral experiments on nitrogen for neutron energies from 1 to 15 MeV

Description: Two integral experiments of neutron scattering and gamma-ray production from nitrogen samples performed at Intelcom Radiation Technology and Oak Ridge National Laboratory were analyzed with Monte Carlo calculations. The experimental results include angular-dependent NE-213 detector count rates for both scattered neutrons and gamma-ray production from a spherical dewar of liquid nitrogen pulsed with a neutron beam with energies from 1 to 20 MeV. Additional results were reported in the ORNL experiments for unfolded scattered neutron and gamma-ray production spectra as a function of detector angle in broad incident neutron energy bins. Multigroup Monte Carlo calculations were made to analyze all the reported results. Conclusions were drawn about the status of the ENDF/B- IV nitrogen cross-section data file from the comparison of calculated and experimental results. 1 table, 44 figures. (auth)
Date: March 1, 1976
Creator: Cramer, S.N. & Oblow, E.M.
Partner: UNT Libraries Government Documents Department

Selection of group energy boundaries using sensitivity theory

Description: An attempt was made to use the sensitivity approach to develop an automated scheme for selecting multigroup energy boundaries so as to minimize the energy groups required to solve a specific problem. As a demonstration of the usefulness of the method, a series of problems involving transport in iron were studied. The general conclusion drawn from the results is that a few group problem dependent cross section sets are apparently practical; and if accurate sets with as few as ten groups are possible in other problem areas, it should be quite practical to choose a few hundred group boundaries for a multigroup library which will have guaranteed accuracy in calculating a fair number of widely different problems. (LBS)
Date: January 1, 1973
Creator: Oblow, E.; Ching, J. & Drischler, J.
Partner: UNT Libraries Government Documents Department