Measurement and calculation of neutron densities in BWR high burn-up fuels

A neutron-scanning device was developed for measuring accurate neutron dens ities of BWR high burn-up fuels up to 65 GWd tU(-1). Characteristic test of this device was done with a Cf-252 source and adopted to measure axial dis tributions of neutron densities of BWR spent fuels with various enrichments (2.0-3.4%), which had been irradiated up to 60 GWd tU(-1) at Fukushima Dai ni Nuclear Power Station Unit 2(2F-2). We found the measured neutron densit ies were proportional to about fourth power of the corresponding burn-up va lues. The neutron densities calculated by the ORIGEN2.1 code and various cr oss section libraries showed good agreements with the measured ones in prof ile and absolute value except for BWR-UE file mainly based on ENDF/B-IV. Th e BS240J32 library based on JENDL3.2 was the best among the investigated li braries. (C) 2001 Elsevier Science B.V. All rights reserved.