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Title: INITIAL EXPERIMENTAL RESULTS FROM ZEUS, AN INTERMEDIATE ENERGY NEUTRON SPECTRUM EXPERIMENT

Abstract

No abstract prepared.

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
784686
Report Number(s):
LA-UR-99-4061
TRN: US0302431
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; NEUTRONS; PHYSICS; LANL

Citation Formats

P. J. JAEGERS, and R. G. SANCHEZ. INITIAL EXPERIMENTAL RESULTS FROM ZEUS, AN INTERMEDIATE ENERGY NEUTRON SPECTRUM EXPERIMENT. United States: N. p., 1999. Web.
P. J. JAEGERS, & R. G. SANCHEZ. INITIAL EXPERIMENTAL RESULTS FROM ZEUS, AN INTERMEDIATE ENERGY NEUTRON SPECTRUM EXPERIMENT. United States.
P. J. JAEGERS, and R. G. SANCHEZ. 1999. "INITIAL EXPERIMENTAL RESULTS FROM ZEUS, AN INTERMEDIATE ENERGY NEUTRON SPECTRUM EXPERIMENT". United States. doi:. https://www.osti.gov/servlets/purl/784686.
@article{osti_784686,
title = {INITIAL EXPERIMENTAL RESULTS FROM ZEUS, AN INTERMEDIATE ENERGY NEUTRON SPECTRUM EXPERIMENT},
author = {P. J. JAEGERS and R. G. SANCHEZ},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1999,
month = 8
}

Conference:
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  • The Zeus experiment is intended to provide nuclear criticality benchmark data for a wide variety of fissile and nonfissile materials in both fast and intermediate neutron energy spectra systems. The authors present a brief description of the Zeus assembly. They then present experimental results, from three configurations, produced during the initial core loading and approach to critical.
  • No abstract prepared.
  • The four HEU, intermediate-spectrum, copper-reflected Zeus experiments have shown discrepant results between measurement and calculation for the last several major releases of the ENDF library. The four benchmarks show a trend in reported C/E values with increasing energy of average lethargy causing fission. Recently, ORNL has made improvements to the evaluations of three key isotopes involved in the benchmark cases in question. Namely, an updated evaluation for 235U and evaluations of 63,65Cu. This paper presents the benchmarking results of the four intermediate-spectrum Zeus cases using the three updated evaluations.
  • During the investigation of various surplus fissile material disposition proposals, uncertainties in the data of SiO{sub 2}/Pu mixtures were discovered. These uncertainties were detected for Si/Pu ratios ranging from approximately 20:1 to 200:1. Additionally, it has been reported that metal/U{sup 235} mixtures also have data uncertainties. These problems with large data uncertainties are typically intermediate spectrum problems, i.e. problems which are dominated by scattering and fissions occurring in the energy range of 10 eV to 1 MeV. ANSI/ANS-8.1-1983 states that the ``bias shall be established by correlating the results of criticality experiments with the results obtained for these same systemsmore » by the method being validated``. There is however, a definite lack of critical experiments with an intermediate neutron spectrum. We have identified two potential areas from which these uncertainties may arise. The first potential source of uncertainty in the nuclear data is due to fact that the cross-sections of the fissile material have not been tested in an intermediate energy spectrum. The second potential source of uncertainty is that the non-fissile material in the mixture may not have been appropriately tested in a critical experiment. To provide this benchmark data a critical experiment is necessary.« less
  • Criticality benchmark data for intermediate energy spectrum systems does not exist. These systems are dominated by scattering and fission events induced by neutrons with energies between 1 eV and 1 MeV. Nuclear data uncertainties have been reported for such systems which can not be resolved without benchmark critical experiments. Intermediate energy spectrum systems have been proposed for the geological disposition of surplus fissile materials. Without the proper benchmarking of the nuclear data in the intermediate energy spectrum, adequate criticality safety margins can not be guaranteed. The Zeus critical experiment now under construction will provide this necessary benchmark data.