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THE FUSED SALT-FLUORIDE VOLATILITY PROCESS FOR RECOVERING URANIUM

Technical Report ·
DOI:https://doi.org/10.2172/4279434· OSTI ID:4279434

A fluoride votality process for recovering enriched uranium from UF/sub 4/-NaF -- ZrF/sub 4/ melts, produced by the dissolution of reactor fuel elements in molten NaF- ZrF/sub 4/ through hydrofluorination, is described. The UF/sub 4/ fluorinated to UF/sub 6/, which volatilizes, and is separated from volatile fission products in a NaF absorption-desorption cycle. In laboratory studies gross beta and gamma decontaminaiion factors of 10/sup 5/ with a uranium loss of less than 0.l% were secured. The product UF/sub 6/ may be conveniently returned to UF/sub 4/ or metal for furthcr use as reactor fuel. Chemical studies, supplementary to process development work, showed that impuritiess possibly oxides, have a much greater effect in the fused salt-fluorination step than such factors as use of nitrogen with the fluorine, or the method of introducing the fluorine into the fluoride melt. The colloidal behavior of NiF/sub 2/, a slightly soluble corrosion product formed in the fluorination, indicated that this material would not interfere in molten salt handling if thc fused salt was not allowed to stand without agitation for prolonged periods. The absorption of UF/sub 6/ in NaF was found to be due to the formation of a UF/sub 6/-NaF complex. The equilibrium between gaseous UF/sub 6/ and solid complex was established for the temperature range of 80 to 320 C. Decomposition of the UF/sub 6/g-NaF complex to a UF/sub 5/-NaF complex does not lead to appreciable uranium loss in the process if specified proeess conditiors are maintained. (auth)

Research Organization:
Oak Ridge National Lab., Tenn.
DOE Contract Number:
W-7405-ENG-26
NSA Number:
NSA-13-010983
OSTI ID:
4279434
Report Number(s):
ORNL-2661
Country of Publication:
United States
Language:
English