Analysis of Reactor Physics Experiment for the Irradiated LWR MOX Fuels

As an important part to validate the LWR core neutronics analysis methods, Japan Nuclear Energy Safety Organization (JNES) has been participating in the REBUS international program and performing analyses and evaluations of the reactor physics experiment data including the irradiated fuels. In REBUS program, physics experiments were performed at the VENUS critical test facility in SCK/CEN, Belgium, in which the five core configurations were tested. In each core configuration, the central part of the 3.3%- and 4%-enriched UO{sub 2} fuel core was replaced by the test bundle of (1)fresh MOX fuel, (2)medium-burnup MOX fuel, (3)high-burnup MOX fuel, (4)fresh UO{sub 2} fuel, and (5)irradiated UO{sub 2} fuel. Measured parameters are critical water level, water level reactivity, fission rate distributions, and neutron flux distributions. In this paper, the results of the fresh MOX and medium-burnup MOX core critical experiments and analysis are presented. The medium-burnup MOX fuel used in this test is 6.9% in initial fissile enrichment and the burnup averaged over the fuel rods is 20 GWd/t. In the core critical analysis, a continuous energy Monte Carlo code MVP was used with the JENDL-3.2 nuclear data library as well as a deterministic analysis code SRAC. The calculated results are compared withmore » the experimental ones. (authors)« less