SALT-PHASE CHLORINATION OF REACTOR FUELSⅡ. ARCO PROCESS DEFINITION AND SCOPING STUDIES

摘要

The dissolution of reactor fuel alloys in molten chlorides is described. The basic ARCO process has been investigated principally as a head-end treatment of zirconium-uranium alloys. The alloy is rapidly dissolved in molten lead chloride at 520°C, and zirconium is simultaneously volatilized as the tetrachloride. Uranium is recovered from the salt matrix by leaching with 8M nitric acid. Lead chloride is regenerated by either dissolution of lead in nitric acid followed by metathesis with hydrochloric acid, or by direct chlorination. Several nickel alloys dis¬played reasonably low corrosion resistance in the lead-lead chloride system. The process promises to be economically competitive with other zirconium fuel processes and at the same time exhibits several advantages, such as rapid but controlled reaction rates, freedom from fluoride ion and recycling gases, appreciably smaller final uranium decontamination equip¬ment, and immediate separation of zirconium as a dry compact waste. Tentative flowsheets for a five kilogram per day uranium plant are presented.nModification to include direct chlorination of fuel in the dissolver vessel is shown to dissolve stainless steel and most other fuel component metals at practical rates. In this case the fused chloride serves as a medium to remove the reaction heat and non-volatile reaction products.