Selection and benchmarking of computer codes for research reactor core conversions

A group of computer codes has been selected and obtained from the Nuclear Energy Agency data bank in France for the core conversion study of highly enriched research reactors. The ANISN, WIMS-D4, MC2, COBRA-3M, FEVER, THERMOS, GAM-2, CINDER, and EXTERMINATOR codes were selected for the study. For the final work, THERMOS, GAM-2, CINDER, and EXTERMINATOR were selected and used. A one-dimensional thermal-hydraulics code has also been used to calculate temperature distributions in the core. The THERMOS and CINDER codes have been modified to serve the purpose. Minor modifications have been made to GAM2 and EXTERMINATOR to improve their utilization. All of the codes have been debugged on both CDC and IBM computers at the University of Illinois. The International Atomic Energy Agency (IAEA) 10-MW benchmark problem has been solved. Results of this work have been compared with the IAEA contributors' results. Agreement is very good for highly enriched uranium fuel. Deviations from the IAEA contributors' mean value for low enriched uranium fuel exist, but they are small enough in general. Deviation of k /SUB eff/ is about 0.5% for both enrichments at the beginning of life and at the end of life. Flux ratios deviate only about 1.5% from the IAEA contributors' mean value