Monte Carlo calculation analysis of measurements of fission rate distributions in light-water-moderated cores loaded with mixed oxide and UO2 fuels

摘要

To extend the information on the validation of the JENDL-4.0 nuclear data library, continuous-energy Monte Carlo calculation was applied to the analysis of the measured core radial fission rate distributions in the light-water-moderated cores loaded with mixed oxide (MOX) and UO2 fuel rods. The measured results were taken from the reports of the critical experiments performed using the Tank-type Critical Assembly (TCA) of the Japan Atomic Energy Agency in the 1970s. The PuO2 contents of the MOX fuel ranged from 1.14 wt to 3.37 wt and the enrichments of the UO2 fuel from 1.180 wt to 2.596 wt. The lattice pitches were from 1.660 cm to 1.956 cm. A half number of cores in the analyzed 30 cores were mainly loaded with the MOX fuel rods and the others were the MOX-UO2 mixed cores or the UO2 cores. The calculated results generally well reproduced the measured fission rates of the MOX and UO2 fuel rods in the test fuel assemblies and those in the x-direction and diagonal direction of the cores.