Abstract: Background: NJOY is used widely nuclear data processing program that can convert the data format of ENDF/B nuclear database into WIMS format of the multi-group cross section database. Purpose: This study aims to produce a multi-group database of WIMS-D format on the basis of the latest release of nuclear evaluation library ENDF/B-VII.1 by using nuclear data processing program NJOY-99. Methods: In allusion to basic fuel cell homogenization calculation benchmark problem of the light water reactor (LWR), taking the 235U and 238U nuclide as the main objects of analysis, the effect on processing time of making cross section library, as well as integral parameters ΔKeff and data sensitivity of selecting input parameters of the NJOY program were compared and analyzed, which optimized the option of input parameter. Results and Conclusion: The results of validating on benchmark problems showed that the production of the multi-group database was correct, which embodied the high accuracy of calculation and provided the basis data of fuel assembly homogenization calculation for pressurized water reactor.

Key words: ENDF/B-VII.1, WIMS, NJOY-99, Nuclear data library