Fast Breeder Reactor Core Concept to Improve Nuclear Proliferation Resistance

A sodium-cooled MOX-fueled FBR core concept to improve nuclear proliferation resistance was proposed. First, we set an index for the nuclear proliferation resistance. In a previous study, reactor-grade Pu was defined such that the Pu-240 isotopic ratio was larger than 18%. Another study defined nuclear proliferation resistance with the Pu-238 isotopic ratio considering its higher spontaneous fission rate and decay heat. We tentatively use the total isotope composition ratio of Pu-238 and Pu-240 as a proliferation resistance index in line with the earlier studies. Next, we designed the sodium-cooled mixed-oxide (MOX)-fueled core concept with the breeding ratio (BR) of over 1.1 without a radial blanket. To attain the index for nuclear proliferation resistance, we added minor actinides (MAs) to the axial blanket fuel (AB). Contents of MAs in the AB to achieve the proliferation resistance index were evaluated. For the case of Np as a representative MA, the minimum content of Np to achieve the index was 3%. And, for the case of loading all MAs, the minimum content of MAs was 10.5%.