Recovery of plutonium from HEPA filters by Ce(IV)-promoted dissolution of PuO/sub 2/ and recycle of the cerium promoter

Conference · Tue Jan 01 04:00:00 EST 1980

OSTI ID:5324555

Leuze, R. E.; Bond, W. D.; Scheitlin, F. M.

The experimental studies carried out included (1) the electrolytic production of Ce(IV) from Ce(III), (2) the leaching of refractory PuO/sub 2/ from HEPA filter materials with maintenance of Ce(IV) concentrations by anodic oxidation during leaching, and (3) evaluation of methods for contacting the HEPA solids with the leaching solution and for separating the solid residue from the leaching liquor. Anodic oxidation of Ce(III) was accomplished with an electric current efficiency of about 85% at current densities of 0.04 to 0.4 A/dm/sup 2/ at a platinum anode. Refractory PuO/sub 2/ was dissolved by a 4.0 M HNO/sub 3/ - 0.1 M Ce(IV) solution in 1.5 h at 100/sup 0/C using stirred-contact leaching of the solids or by recirculating the leachant through a packed column of the solids. Cerium (IV) concentrations were maintained continuously by anodic oxidation throughout leaching. Dissolution times up to 10 h were required unless the HEPA media were oxidized initially in air at 300/sup 0/C to destroy carbonaceous species which consumed Ce(IV) more rapidly than it could be regenerated by anodic oxidation. Leaching solids in packed columns avoided the relatively difficult liquid-solids separation by centrifugation which was required after stirred-contact leaching; however, the solids handling difficulties associated with charging and discharging of the packed columns in a remote environment remain a significant design obstacle. A chemical flowsheet is proposed for the recovery of actinides from HEPA filters. A 4 M HNO/sub 3/ - 0.1 M Ce(IV) nitrate solution is used as the leachant and the Ce(III) is recycled to the leaching operation using bidentate solvent extraction.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: USDOE Office of Nuclear Waste Management
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5324555
• Report Number(s): CONF-800743--1
• Country of Publication: United States
• Language: English

Related Subjects

050800* -- Nuclear Fuels-- Spent Fuels Reprocessing
052001 -- Nuclear Fuels-- Waste Processing
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ACTINIDE COMPOUNDS
ACTINIDES
AIR FILTERS
AQUEOUS SOLUTIONS
CERIUM COMPOUNDS
CERIUM NITRATES
CHALCOGENIDES
CHEMICAL REACTIONS
DISPERSIONS
DISSOLUTION
ELEMENTS
EQUIPMENT
FILTERS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
LEACHING
METALS
MIXTURES
NITRATES
NITRIC ACID
NITROGEN COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLUTONIUM
PLUTONIUM COMPOUNDS
PLUTONIUM DIOXIDE
PLUTONIUM OXIDES
POLLUTION CONTROL EQUIPMENT
RARE EARTH COMPOUNDS
RECOVERY
SEPARATION PROCESSES
SOLUTIONS
TRANSURANIUM COMPOUNDS
TRANSURANIUM ELEMENTS