PROLIFERATION RESISTANCE ANALYSIS OF MULTIPLE RECYCLING OF REENRICHED REPROCESSED URANIUM FUEL IN COMMERCIAL LIGHT WATER
REACTORS

The rapid growing demand for electricity combined with the limitations of renewable energy such as wind and solar and also excessive CO2 emission from fossil fuels make nuclear power more attractive as an important supply of energy. However, to develop a robust nuclear regime, one of the aspects that should be considered is nuclear non-proliferation. The sensitive nuclear proliferation parts of nuclear fuel cycles such as reprocessing of spent fuel has been subject of many studies over years. Proliferation resistance assessment of re-enriched reprocessed uranium fuel discharged from a light water reactor water-cooled water-moderated energetic reactor (VVER) is analyzed in this study by estimating the growth in the desired amount of even numbered uranium and plutonium isotopes, especially 236U and 238Pu to make the spent fuel less attainable for military purposes. During the fuel burnup non-fissile uranium isotope, 236U is considered for proliferation resistance as one of the signature isotopes for the reprocessed uranium (RepU). 236U is generated from its precursor 235U by successive neutron capture, and one of the reaction chains to produce 238Pu is transmuting minor actinides starting from 237Np, which is a result of beta decay of 236U. Multiple recycling enables 236U concentration to keep growing after each centrifuge re-enrichment and irradiation thus resulting in contributing to 238Pu development in the spent fuel. 238Pu denatures Pu because of its high spontaneous fission neutron emission rate and decay heat. Also, the spent fuel at the end of multiple recycling accumulates 236U in the fuel in such a way that further re-enrichment of 235U does denature U due to the coenrichment of 236U with 235U.