Development of Shielded Ion Microprobe Analyser for Irradiated Fast Reactor Fuel and Material Examination

A shielded ion microprobe analyser(SIMA) has been developed for the mass spectral analysis of bulky highly activated mixed oxide fuels and their components. Radiation shielding of the instrument ensures the radiation dose rate less than 0.52[C/kg.h](2.0[mR/h]) at the outer surface of the SIMA for 185[GBq](5.0[Ci]) of Co-60 source. The analyses have been carried out with urania-plutonia fuels, B₄C control rods and stainless steel fuel claddings irradiated in Japanese Experimental Fast Reactor “JOYO”. The isotopic compositions and the distributions of U and Pu, and the fission products’ behaviour in the fuel, boron and lithium characteristics in the control rods and the chemical information at inner and outer surfaces of the cladding can be obtained very accurately and quickly. We found no serious problems in function of the instrument and in reliability working with the shielding capability in comparison with the conventional one.