The feasibility of recycling activated steel first wall/blanket materials from fusion reactors

Process routes are outlined for conversion of radioactive steel scrap (e.g. LA7, FV448, 316, OPTSTAB) from fusion reactors to feedstock for the production of new components, with the requirement that the amount of radioactivity leaving the system be minimised. The proposed route comprises vacuum induction melting, followed by continuous casting or powder production and compaction using isostatic techniques. It is considered that reprocessing is feasible provided the contact dose rate of the material is < 25 mSv h exp --1 . A storage time of about 70 years would be required for low-activation steels of currently-anticipated compositions to attain this value. Active secondary wastes will be generated at all stages; some of these can be recycled to the melting unit, while others will require disposal. The fraction of the initial radioactivity retained in the recycled material varies from approx 80-95%, depending on the starting composition and the extent to which transmutation-induced changes may need to be compensated for during remelting. Graphs. 11 ref.--AA