NEUTRON CROSS SECTION EVALUATIONS OF FISSION PRODUCTS BELOW THE FAST ENERGY REGION

Technical Report · Thu May 11 04:00:00 EDT 2000

DOI:https://doi.org/10.2172/759039· OSTI ID:759039

OH, S Y ^[1]; CHANG, J; MUGHABGHAB, S

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1. BROOKHAVEN NATIONAL LABORATORY

Neutron cross section evaluations of the fission-product isotopes, {sup 95}Mo, {sup 99}Tc, {sup 101}Ru, {sup 103}Rh, {sup 105}Pd, {sup 109}Ag, {sup 131}Xe, {sup 133}Cs, {sup 141}Pr, {sup 141}Nd, {sup 147}Sm, {sup 149}Sm, {sup 150}Sm, {sup 151}Sm, {sup 152}Sm, {sup 153}Eu, {sup 155}Gd, and {sup 157}Gd were carried out below the fast neutron energy region within the framework of the BNL-KAERI international collaboration. In the thermal energy region, the energy dependence of the various cross-sections was calculated by applying the multi-level Breit-Wigner formalism. In particular, the strong energy dependence of the coherent scattering lengths of {sup 155}Gd and {sup 157}Gd were determined and were compared with recent calculations of Lynn and Seeger. In the resonance region, the recommended resonance parameters, reported in the BNL compilation, were updated by considering resonance parameter information published in the literature since 1981. The s-wave and, if available, p-wave reduced neutron widths were analyzed in terms of the Porter-Thomas distribution to determine the average level spacings and the neutron strength functions. Average radiative widths were also calculated from measured values of resolved energy resonances. The average resonance parameters determined in this study were compared with those in the BNL and other compilations, as well as the ENDF/B-VI, JEF-2.2, and JENDL-3.2 data libraries. The unresolved capture cross sections of these isotopes, computed with the determined average resonance parameters, were compared with measurements, as well as the ENDF/B-VI evaluations. To achieve agreement with the measurements, in a few cases minor adjustments in the average resonance parameters were made. Because of astrophysical interest, the Maxwellian capture cross sections of these nuclides at a neutron temperature of 30 keV were computed and were compared with other compilations and evaluations.

• Research Organization: Brookhaven National Lab., Upton, NY (US)
• Sponsoring Organization: DOE/SC (US)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 759039
• Report Number(s): BNL--NCS-67469; KB0401040; KB0401040
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CAPTURE
CESIUM 133
COHERENT SCATTERING
CROSS SECTIONS
EUROPIUM 153
FAST NEUTRONS
FISSION PRODUCTS
GADOLINIUM 155
GADOLINIUM 157
MOLYBDENUM 95
NEODYMIUM 141
NEUTRON TEMPERATURE
PALLADIUM 105
PORTER-THOMAS DISTRIBUTION
PRASEODYMIUM 141
RHODIUM 103
RUTHENIUM 101
SAMARIUM 147
SAMARIUM 149
SAMARIUM 150
SAMARIUM 151
SAMARIUM 152
SILVER 109
STRENGTH FUNCTIONS
TECHNETIUM 99
XENON 131