Fiscal Year 2001 Status Report for the Investigation of Reactivity Effects Due to Perturbations in Cross-Section Temperature

The objective of the current work is to calculate changes in system multiplication due to perturbations in cross-section temperature. Moreover, the study is intended to investigate cross-section perturbations using ENDF/B-VI data which are the most up-to-date cross-section information currently available in the United States. The purpose of this letter report is to document the work that has been completed during the 2001 fiscal year. In addition, the report provides the current status of the temperature-effects study. During the fiscal year, the majority of effort has focused on the development of a 238-group ENDF/B-VI library using the AMPX cross-section processing system. At this point, 340 ENDF/B-VI evaluations have been processed (i.e., 15 thermal and 325 nonthermal evaluations), and a prototypic 238-group library has been developed. Efforts are currently in progress to test the cross-section library for accuracy. Once the library is determined to be suitable for radiation transport calculations, the library will be used to perform reactivity calculations to assess the impact of cross-section temperature perturbations. Regarding the temperature perturbation studies, a FORTRAN program (CRCREAD) has been developed to read the CRCbenchmark models (i.e., MCNP input files) and search for the 130 different isotopes that have been designated by the YMP for further study. Currently, CRCREAD determines if an isotope is present in the CRC benchmark model and determines the physical location of the isotope within the model. In addition, CRCREAD determines the weight fraction of the isotope in a material within the MCNP model. In the future, CRCREAD will be used as a tool to aide in the development of 1-D XSDRNPM input models that will be used in the temperature-effects calculations