Published: 1992
Total Pages: 7
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Work conducted for the Underground Storage Tank Integrated Demonstration supports technology demonstration for tank remediation operations at the US Department of Energy's (DOE) Hanford Site and other DOE sites. Several technical areas within the demonstration are being investigated by the Waste Pretreatment Technology Development task to support final treatment and disposal of Hanford tank waste. The experimental work includes waste characterizations; dissolution, leaching and extraction tests; bulk salt separations by freeze crystallization; and radiochemical separations with extraction chromatography resins. Chemical species and particle size data provide background information for interpreting waste leaching and dissolution data. Tie major crystalline phases in one single-shell tank (SST) waste are sodium nitrate and bismuth phosphate, while the major phases in another SST waste are boehmite, gibbsite, and sodium nitrate. A scanning electron microscopy (SEM) method of particle size analysis shows that many of the sub-micron particles in the two SST wastes appear to be aggregates of smaller, spheroidal particles. In turn, leaching, dissolution, and extraction studies, performed with tank wastes, provide fundamental information needed to evaluate existing pretreatment technologies. Preliminary results from the dissolution of one SST waste indicate that 2M nitric acid may effectively leach enough transuranic material that the sludge could be disposed of as low level waste.