OECD/NEA INTERNATIONAL BENCHMARK ON THE VENUS-2 MOX CORE MEASUREMENTS

Within the framework of the NEA Nuclear Science Committee, theoretical physics benchmarks and multiple recycling issues related to various MOX-fueled systems have been studied. Many improvements and clarifications in nuclear data libraries and calculation methods have been achieved from the results of the theoretical benchmarks performed. However, it was felt that there was also a need to link these findings to data from experiments. Hence, a blind international benchmark exercise based on the two-dimensional VENUS-2 MOX core measurement data was carried out. Twelve participants from ten countries participated in the benchmark. Both the deterministic and the Monte Carlo methods were applied with different nuclear data sets. This paper provides a comparative analysis between calculated and measured results. Comparison with experimental results identified the origins of discrepancies between calculations and measurements and enabled the quantitative comparison of the relative merits of the different calculation methods. The management of excess plutonium produced during the operation of commercial power plants has become important to the nuclear community. Many possible treatments of this issue have been envisaged. The options include vitrification of the spent fuel and geological disposal with other nuclear waste without prior reprocessing, and burning of the plutonium fuels in nuclear power plants for the production of electricity. The preferred option depends on whether plutonium is seen as a waste or a high quality nuclear fuel. Several countries use plutonium recovered from spent fuel in the form of mixed-oxide (MOX) uranium and plutonium fuel in existing power plants, a well established technology with many years of experience. Nevertheless, re-use of plutonium in PWRs is limited in quantity as well as in quality. Loading of plutonium assemblies in a PWR core is recommended up to 30% of the total loading to avoid any problem which might be caused by power peaking or degradation of safety parameters. The quality of plutonium decreases after a few recycles (Rome 1991). The actual practice for MOX fuel use is therefore not sufficient to stabilize the stockpile of plutonium extracted from spent fuel.