Co-precipitation of Np(VI,V) and Pu(VI,V) from alkaline solutions with some carriers formed by the method of appearing reagents

Conference · Tue Oct 01 04:00:00 EDT 1996

OSTI ID:370581

Krot, N N; Shilov, V P; Bessonov, A A ^[1]

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1. Inst. of Physical Chemistry, Moscow (Russian Federation); and others

Radioactive wastes stored in underground tanks at the Hanford Site will be processed and immobilized for final disposal into low-level (LLW) and high-level (HLW) fractions. Long-lived Np and Pu isotopes must go to the HLW fraction because of their ecological hazard. Co-precipitation of Np(VI,V) and Pu(VI,V) with carriers generated in alkaline solution by redox reactions, hydrolysis, or catalytic decomposition of soluble species (i.e., the method of appearing reagents, MAR) was tested to achieve the separation. The hydroxides of Mn(IV), Mn(II), Fe(III), Co(III), Co(II), and Cr(III) and sodium uranates were selected as carriers. They can be obtained by the MAR in alkaline media by the reduction of MnO{sub 4}{sup -}, MnO{sub 4}{sup 2-}, FeO{sub 4}{sup 2-}, and CrO{sub 4}{sup 2-}; the hydrolysis of [Fe(CN){sub 5}NO]{sup 2-}, [Co(NH{sub 3}){sub 6}]{sup 3+}, [Co(NH{sub 3}){sub 5}Cl]{sup 2+}, and Cr{sup 3+}; or the catalytic decomposition of UO{sub 2}(O{sub 2}){sub 3}{sup 4-}. Optimum conditions for these reactions were determined based on kinetics and completeness of the carrier isolation. Decontamination factors between 100 and 1000 were achieved by precipitation of Co(III), Co(II), and Cr(III) hydroxides and sodium uranate in the range 0.5 to 8 M NaOH. Coprecipitation of Np(VI,V) and Pu(VI,V) by Fe(III), Mn(IV), and Mn(II) hydroxides were less effective.

• OSTI ID: 370581
• Report Number(s): CONF-960376--
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
CHROMIUM HYDROXIDES
COBALT HYDROXIDES
COPRECIPITATION
DECOMPOSITION
DECONTAMINATION
HANFORD RESERVATION
HIGH-LEVEL RADIOACTIVE WASTES
HYDROLYSIS
IRON HYDROXIDES
LOW-LEVEL RADIOACTIVE WASTES
MANGANESE HYDROXIDES
NEPTUNIUM
PLUTONIUM
RADIOACTIVE WASTE PROCESSING
REDOX REACTIONS
REDUCTION
SODIUM URANATES
TANKS