Comparative Analysis on Fuel Breeding for Less Moderation Ratio of Water Cooled Reactor

Abstract

Nuclear fuel breeding aspect of water-cooled reactor become one of the important issues to extend the sustainability aspect of nuclear fuel in line with fast breeder reactor program with closed fuel cycle concept. In the present study, nuclear fuel sustainability aspect of conversion ratio, several fuel-recycling schemes, nuclear fuel composition and isotopic plutonium composition have been evaluated based on a water-cooled reactor of light water (H2O) and heavy water (D2O) as coolants for less ratio of moderator to fuel (MFR). Less fissile content is required for plutonium (Pu) recycling scheme than once through scheme for both coolant types and it requires more fissile content for heavy water coolant (D2O) of U-235 than light water coolant for both fuel cycle schemes. Plutonium recycling scheme obtains higher fuel conversion ratio than once through for both coolant types and more fuel conversion ratio is shown by heavy water coolant than light water coolant. It shows near fuel breeding can be obtained by light water coolant and breeder reactor capability can be obtained by heavy water coolant. Higher composition of trans-uranium including plutonium and minor actinides (MA) are shown by plutonium recycling case and heavy water coolant, which is estimated that can contribute to have more fuel-breeding capability. Composition of plutonium and americium increases significantly for heavy water coolant, while neptunium and curium compositions are almost the same for both coolants. Plutonium recycling scheme and heavy water coolant produces more even mass plutonium isotopes such Pu-238, Pu-240 and Pu-242 as fertile material, which can be estimated to give better fuel breeding capability and higher level proliferation resistant.