ZZ DLC-18 NAB, 100 Neutron-Group Cross-Section Library of Na and Al for ANISN, DOT, MORSE Neutron Transport

1 - Nature of physical problem solved: Format: ANISN, DOT, and MORSE; Number of groups: 100 neutron group; Nuclides: sodium or sodium contained in aluminium tanks. With following impurities: calcium: 400 ppm; oxygen: 200 ppm; potassium: 150 ppm; hydrogen: 50 ppm. Origin: ENDF/B-3 MAT 1156 sodium and MAT 1135 aluminium. Weighting spectrum: - 1/E weighting spectrum for non-thermal energies, - thermal group cross sections were determined by assuming a Maxwellian weighting function and a constant scattering cross section and a 1/v absorption cross section. DLC-18 is suitable for multigroup neutron transport calculations in sodium or sodium contained in aluminium tanks, such as the ORNL-LMBNR sodium benchmark experiment (2). The retrieval program manipulates such that it can be used in codes such as ANISN, DOT, and MORSE. 2 - Method of solution: The 100 neutron group, P3 data were produced by the ORNL Mathematics Division, using SUPERTOG, and a 1/E Weighting spectrum for non-thermal energies. The energy group structure is that used for the GAM-2 which covers the energy range from 14.92 MeV to thermal. The thermal group cross sections were determined by assuming a Maxwellian weighting function and a constant scattering cross section and a 1/v absorption cross section. This data represents a P3 Legendre expansion approximation for neutron elastic scattering. Inelastic neutron scattering was treated as isotropic in the lab system. The multigroup cross sections were generated from a preliminary version of the ENDF/B-3 MAT 1156 sodium and MAT 1135 aluminium. Subsequent changes to the evaluated data prior to its official release as part of ENDF/B-3 would affect the data in DLC-18/NAB somewhat, but probably not significantly. Because the materials used in the experiment were not free from impurities, these were included as follows: calcium: 400 ppm; oxygen: 200 ppm; potassium: 150 ppm; hydrogen: 50 ppm