Testing of a JEF-1 Based WIMS-D Cross Section Library for Migration Area and K-Infinity Predictions for LWHCR Lattices

摘要

The cell code WIMSD4 is used for the analysis of PROTEUS-LWHCR experiments. A library for this code which is based on the European evaluation JEF-1 was produced at EIR using the Los Alamos NJOY system with its module WIMSR and the Canadian management code WILMA. In general, this library delivered more accurate eigenvalues and reaction rates than the WIMS-Standard and WIMS81 libraries did in comparison to experimental values from PROTEUS-LWHCR Cores 1-3. However, large discrepancies (up to about 10%) occured between calculated migration areas (M sup 2 ). Additional investigations have been undertaken to clarify this problem, since theoretical M sup 2 -values are needed for deducing k-infinity in the experiments. This has been done in the context of calculations for a reference LWHCR test lattice. The following major reasons for these deviations were found. First, the self-scattering term in non-moderators (P sub 0 matrix) in the JEF-1 library was not transport corrected. Second, Standard and JEF-1 libraries use infinite dilute cross sections for sup 238 U, whereas the WIMS81 library uses fully shielded cross sections. Third, the standard library uses the row formula for the transport correction, whereas the inflow formula is applied in the case of JEF-1 and WIMS81 libraries. Lastly, oxygen and sup 238 U scattering cross sections in the fast energy range are smaller in the case of the WIMS81 library. Differences in calculated k-infinity values between the currently used library and WIMS81 (up to 3%) come (in order of importance for the reference LWHCR lattice) mainly from resonance cross sections for sup 240 Pu capture, sup 238 U capture and sup 239 Pu fission. Recommendations have been made for generating a new JEF-1 library using updated versions of WIMSR and WILMA. (ERA citation 12:028611)