Solvent Extraction Process for Recovery of Americium-241 at Hanford

Solvent extraction [tributyl phosphate (TBP)] operations to recover plutonium from unirradiated scrap have been performed at the Hanford Site since 1955. The aqueous raffinate (CAW stream) from the TBP plutonium extraction process contains, typically, <10 mg/L plutonium and 2-10 mg/L 241 Am. This latter isotope is present in the plutonium scrap as the result of beta decay of 241 Pu (t 1/2 = 14.4 y); trivalent americium does not accompany plutonium from the HNO 3 -HF feed solution into the TBP solvent. In the early years of plutonium scrap processing operations, the CAW stream was routed to trenches ( 1 ) specially excavated in Hanford soil. Batch recovery of americium was started in 1965. Later (1970-1976), a continuous countercurrent solvent extraction process employing DBBP (dibutylbutyl phosphonate) as the extractant was operated to recover, at least partially, plutonium and americium values from the CAW stream. Aqueous waste from the DBBP extraction process, still containing some plutonium and americium,