Research On Neutronic And Thermal Characteristics Of MOX Fuel In Supercritical Water Cooled Reactor

In order to meet the higher demand of the nuclear power market, a new generation of nuclear power units need large improvement in the aspects of sustainable, economic, security and stability, non-proliferation. The Generation IV International Form (GIF) is a cooperative international endeavor organized by several advanced nuclear countries at the beginning of this century, and six nuclear energy system is selected as the Generation IV concept systems. Where, supercritical water cooled reactor (SCWR) is the only one to use water as the working fluid. It has advantage as the simplified structure, and the high economy. MOX fuel is short for mixed oxide fuel, commonly used by UO2and PUO2. Using MOX fuel can increase fuel efficiency, reduce nuclear waste processed, reduce the treatment cost, prevent nuclear proliferation, and safeguard world peace.Using MOX fuel in SCWR can get higher heat efficiency and fuel efficiency. However, there are many differences in performance between MOX fuel and UO2fuel. So, the strict analysis and verification for using MOX fuel in SCWR is needed to guarantee the safety operation of the reactor.The calculation and anlysis platform for neutonic and thermal characteristics of SCWR with MOX fuel is developed, which is DRAGON+SCAC. Then, the calculation is carried out to estimate the power distribution, neutron spectrum, reaction coefficient, multiplication factor, working medium temperature distribution, fuel temperature distribution, influence of different water rod structure and so on. Comparing with the characteristics of SCWR with UO2fuel, the SCWR with MOX fuel has harder energy spectrum, greater depth of fuel depletion, higher radial power uneven factor, better moderator temperature negative reactive, higher fuel center temperature, lower coolant outlet temperature, lower fuel cladding temperature. If MOX fuel include more PUO2content, the reactor has more greater depth of fuel depletion, lower moderator temperature negative reactive. When MOX fuel has same content of PuO2, weapons grade plutonium has higher radial power uneven factor, more greater depth of fuel depletion, lower moderator temperature negative reactive than reactor grade plutomium. Through the analysis of the similarities and differences above, a new improved assembly design is presented. Through calculating, the new improved assembly design has harder energy spectrum, lower radial power distribution than reference design, and can get same coolant outlet temperature, more lower fuel cladding temperature and fuel middle temperature through setting proper parameters.A preliminary calculation of system characteristics for the SCWR with MOX fuel is presented and given. In addition, it compares and analyzes the similarities and differences between the results of the SCWR with MOX fuel and that with UO2fuel. According to the analysis, a new SCWR improved assembly design is presented, which could be used to improve the safety performance of SCWR with MOX fuel. It provides a certain reference for the future researches on SCWR.