Carbonylation as a separation technique for removal of non-radioactive species for tank waste

摘要

Much of the waste generated from five decades of weapons production in the US Department of Energy complex contains highly radioactive constituents. With the high cost of permanent disposal space, it is necessary to separate as many of the nonradioactive species from the radioactive as possible. This paper discusses the transfer of carbonyl processing technology from mineral beneficiation and powder metallurgy operations to the separation of Fe and Ni from radioactively contaminated waste streams. Samples of simulated composite Hanford Tank Waste residue were first processed with a calcine/dissolution technique which resulted in a residue powder consisting of 31.9 pct Fe and 3.3 pct Ni. Because of the specification for waste glass compositions, these two constituents become important in determining the number of waste glass logs produced. Pyrometallurgical reduction of the residue powders, followed by subsequent carbonylation, extracted up to 92.0 pct of the Fe and 95.7 pct of the Ni. The resultant product contained as little as 4.9 pct Fe and 0.3 pct Ni. At this level, Fe would no longer be a limiting constituent in the waste glass.