Oxalate precipitation of Pu(III) from very dilute HCl solutions

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:559919

Salazar, R R; Griego, B J; Schulte, L D; McKee, S D ^[1]

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1. Los Alamos National Lab., NM (United States); and others

A typical Pu(III) oxalate precipitation, performed in {approximately}1 M HCl with a modest excess of oxalic acid (and well run), produces a filtrate in the range of 250 to 500 mg/L Pu. Poorly controlled oxalate precipitations can produce multi-gram/L filtrates. The published solubility expression for Pu{sub 2}(C{sub 2}O{sub 4}){sub 3}{center_dot}10H{sub 2}O is [Pu (mg L{sup -1})] = 3.24 [H{sup +}]{sup 3} [H{sub 2}C{sub 2}O{sub 4}]{sup -3/2}. This expression suggests that dramatic reductions in Pu{sub 2}(C{sub 2}O{sub 4}){sub 3}{center_dot}10H{sub 2}O solubility, and a corresponding reduction in Pu loss to filtrate, are possible with fairly minor adjustments to H{sup +} concentration. A series of experiments run at full scale has demonstrated that Pu losses to oxalate filtrate can be significantly lowered by adjusting H{sup =} concentration into the pH 1-5 range. Filtrates less than 1 mg/L Pu have been obtained, resulting in Pu recovery efficiencies of over 99.99% for this unit operation. This technology fits within our goals of high efficiency in recovery of Pu into forms suitable for safe long-term storage, while minimizing activity and hazards of ancillary waste streams.

• OSTI ID: 559919
• Report Number(s): CONF-970443--
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
HYDROCHLORIC ACID
OXALIC ACID
PRECIPITATION
RADIOACTIVE WASTES
SOLUBILITY