Aspects of 238Pu production in the experimental fast reactor JOYO

Experimental determination of 238Pu in 237Np samples irradiated in the experimental fast reactor JOYO was done as part of the demonstration of 238Pu production from 237Np in fast reactors within the framework of the protected Pu production project, which aims at reinforcement of proliferation resistance of Pu by increasing the 238Pu isotopic ratio. 238Pu production amount in the irradiated 237Np samples was determined by a radioanalytical technique. Aspects of 238Pu production were examined on the basis of the present radioanalysis. The 238Pu production amount depends on the neutron spectrum which can range from that of a typical fast reactor to a nearly epi-thermal spectrum. It is concluded that the fast reactor has not only high potential for use in protected Pu production, but also as an incinerator for excess Pu.