A Neutron Cross Section Evaluation for ²³²Th in the E_n <20 MeV Energy Range

Abstract

The neutron interaction cross sections in the energy range below 20 MeV for ²³² Th have been completely revised starting from both recent experimental data^{1), 2)} and theoretical results given by an updated version of the CIRCE, PO- LIFEMO and PENELOPE³⁾ chain codes for direct reaction, compound nucleus and direct scattering calculations. The angular distributions for inelastic scattering by the first three excited levels, taking into account the nuclear deformation up to the hexadecapole term, have been calculated and compared with experimental results. The new data set has been tested in calculations performed on the THOR fast criticality experiment. The transport calculations were carried out in spherical geometry through the XSDRNPM transport module of the SCAMPI Data Processing System. *The results were compared with the corresponding ones obtained with other ²³²Th data files (ENDFB VI-3, JEF-2.2 and JENDL-3.2).

Keywords:

• Th 232
• optical model
• cross section evaluation
• THOR fast criticality benchmark