Possibilities of Better Utilization of MOX fuel in VVER type reactors by optimizing neutron spectrum

Abstract

Abstract The introduction of MOX fuel in modern nuclear fuel cycles has posed attention in all leading nuclear countries. However, the introduction of plutonium in the fuel loading in light water reactors has neutron-physical limitations. Improve the consumption of plutonium in MOX fuels is one of the important issues that have to be studied to decrease the risk of proliferation resistance. The impact of varying neutron spectrum on the discharged plutonium was studied through the variation of the fuel pellets diameter in a VVER type MOX fuel assembly without changing the lattice pitch. Neutronic calculations were performed using: MCU, Serpent, and GETERA codes. It was shown that the neutron spectrum plays a dominant role in the consumption and production of nuclides. Also, the usage of assemblies with high moderator to fuel volume ratio burned higher amounts of fissile plutonium in comparison with assemblies with low moderator to fuel volume ratio.