Waste raffinates, actinides separation

Separation of Actinides from Purex-Type High Active Waste Raffinates... 

A litre of waste shown in Table I, when calcined, results in the production of 250 g of total solids. The plot shown in Figure 1 describes significant actinide concentrations in ICPP calcine from a typical raffinate as a function of time. Though uranium and neptunium are present in the calcine, their contribution to alpha activity is not significant. It is apparent that separation factors of xlOO must be attained for the Pu and Am to... 

The thrust of the experimental program at ICPP was to find a separation procedure that would separate plutonium, americium, and curium from high-level first-cycle raffinate (see Table I) and leave behind the cladding elements, salting agents, and the bulk of the fission products. Fission-product lanthanides, because of their similar valence and ionic size, would be expected to follow americium in nearly any simple separation scheme. Americium and curium are present in ICPP waste as trivalent ions while plutonium is most likely present as both Pu(IV) and Pu(VI). Any separation scheme must be applicable to all these ionic actinide species. 

Before solvent extraction, the feed was treated with manganous nitrate and less than equivalent permanganate to convert plutonium to Pu(VI). Tests in miniature mixer-settlers with synthetic feed solution but not containing Cf showed acceptably small concentrations of actinides in the aqueous waste (1AW) and organic raffinate (1CW) streams, and also acceptable separation of plutonium from curium and americium. 

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