Electro-slag melting of plutonium-contaminated metallic waste, 3

To establish the process for the treatment of plutonium-contaminated metallic wastes, the electro-slag melting method was studied using a Joule-heated mock-up furnace. This method is a process melting contaminated metal into molten slag in a copper mold, then gradually solidifying in the same mold. In this process, the PuO2 contaminating metallic wastes is expected to be transferred to molten slag. In the present study, HfO2 was used instead of PuO2, and stainless steel and carbon steel were used as the contaminated metals. The dimensions of the mock-up furnace were so selected that it can be housed in a α-tight glove box. From the present experiment, it was shown that the HfO2 was uniformly distributed and immobilized in the solidified slag and in the metal ingots, and that 96 % of HfO2 was removed from the metallic wastes, while remaining 4 % being immobilized in the ingots. Small amount of secondary wastes was generated in this process because of the absence of refractories and the repeated use of slags. (Aoki, K.)