A Study On The Burn-up Characteristics And Transmutation Of Inert Matrix Fuels

China occupies a key position in world nuclear power development. Large installed capacity is bound to preserve a large sum of spent fuel. Minor actinides(MA) produced in commercial nuclear fission features long half-time period and radioactive toxicity. Inappropriate disposition of nuclear wastes poses a potential, long-term threat to people’s living environment. As a result, China puts forward sustainable nuclear fuel cycle and waste disposition in terms of fission sustainable development, minimizing nuclear waste. Moreover, it attempts to develop advanced nuclear energy system, improve fuel availability, achieving transmutation of MA.In recent years, inert matrix fuels(IMFs) adopted in light-water reactor can effectively reduce MA from the source and achieve transmutation of MA. This research selects 2 typical IMFs, Pu O2+Zr O2+Mg O and Pu O2+Th O2 in order to study the burn-up characteristics of IMF and the research is performed as the follows:(1) The burn-up characteristics of IMF under different volume fraction of Pu O2 is performed and it makes a contrast with UO2 and MOX.(2) It performs MA transmutation study in IMF cell through uniform loading and central loading in MA.(3) Based on burn-up characteristics calculation, it analyzes IMF element burn-up characteristics in CONFU element configuration and symmetrical element configuration.The results show that:(1) as the total burn-up time is 1095 days, the volume fraction of Pu O2 in both IMFs ranges from 2%~10% and both two kinf at EOL(end of life) are above 1.But the burn-up reactivity swing of Pu O2+Zr O2+Mg O is larger than that of Pu O2+Th O2. MA at EOL in the latter is obviously smaller than the former. Under the same equivalent heavy mass percent, MA in MOX and UO2 at EOL are both larger than two IMFs.(2) When MA performs uniform loading, the IMF transmutation MA cell is calculating burn-up reactivity. Even though MA at EOL indicates a trend of enlargement, with the increasing number of MA volume fraction, under the equivalent Pu O2, MA at EOL decreases and the destruction efficiency of TRU is substantial. When MA is central loading, referring to MA transmutation in fast neutrons, a fast neutron zone(FNZ) is established to calculate MA burn-up reactivity in the present PWR cell. It is found that there are fast neutrons in central zone of FNZ and the net transmutation efficiency reaches up to 80% when add MA.(3) According to the burn-up characteristics and MA yields at EOL in IMF uniform loading MA transmutation element and MA central loading transmutation element, the MA destruction efficiency in CONFU element configuration is higher than that of symmetrical element configuration from the perspective of burn-up characteristics.The above conclusions provide feasible solution to optimize the application of IMF in PWR, IMF transmutation MA cell and element.