Acid dissolution treatment of aged plutonium oxide

Emori, Tatsuya; Kitatsuji, Yoshihiro  ; Ban, Yasutoshi  

The use of Radioisotope Thermoelectric Generator (RTGs) using the decay heat of Pu-238 is being considered as a power source for permanently shadow regions on the lunar surface, where solar power is impractical, as well as for deep-planet missions far from Jupiter. However, Japan does not have the capability to produce Pu-238 or the operational performance of its usage. Additionally, it is difficult to employ nuclear fuel materials for space probes in Japan due to regulatory constraints. Consequently, development related to the utilization of Am-241 has been carried out. We performed dissolution experiments using aged PuO powder that has been stored for research purposes, aiming at the mutual separation of Pu and Am. Two experiments were conducted: one using a nitric acid solution and the other using a mixture solution of nitric acid and hydrogen peroxide. The dissolution time with the latter solution was less than half that required for the former. Furthermore, unlike other commonly used oxidants, the use of hydrogen peroxide prevented contamination by salts and metals and minimized potential detrimental effects on the subsequent Pu/Am separation experiments.