Reactive Gas Recycle of Used Nuclear Fuel - Sulfur Hexafluoride

摘要

Research on Reactive Gas Recycling of Used Nuclear Fuel (UNF) has been initiated at Savannah River National Laboratory (SRNL) as a potentially transformational approach for the separation and reuse of UNF for energy production. This work began using thermodynamic calculations to scope out potential gas-phase separation reactions which might reduce secondary waste stream volumes, process equipment and process complexity. The results of these calculations provided support for the feasibility of a dry recycling concept that would allow for efficient separation of volatile UF6 and select fission products from UNF. This paper discusses experimental results from recent thermogravimetric analysis (TGA) to characterize the reactivity of an alternative non-toxic, non-flammable fluorinating gas (sulfur hexafluoride, SFa) with UO3, U3O8, and various fission product surrogate materials in the form of oxides and metals. The experimental results indicate that the majority of the fission product surrogates form stable solid fluorides and sulfides at temperatures up to 750°C, while the uranium oxides can fluorinate and volatilize at higher temperatures.