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U.S. Department of Energy
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THE DAREX PROCESS: PROGRESS SINCE THE 1958 GENEVA CONFERENCE

Technical Report ·
DOI:https://doi.org/10.2172/4293639· OSTI ID:4293639
Darex Process is a head-end process for stainless steet-containing fuels consisting basically of three steps: (1) dissolution in dilute nitric- hydrochloric acid, (2) chloride removal, and (3) solvent extraction feed adjustment. The process may be carried out continuously, semi-continuously, or batchwise using nitric acid concentrations from 61 to 95 wt.%. Apparatus for continuous operation including instrumentation for the controlled recycle of concentrated nitric acid was assembled and operatcd to process APPR fuel elements. Reflux flowsheets were developed on a 1 to 2 liter scale for both batchwise and semi-continuous operation using either 95 or 61 wt. % nitric acid to volatilize and/or decompose chloride. These four flowsheets, employing a period of refluxing with high nitric acid concentrations, accomplished chloride removal to less than 350 ppm by the batchwise addition of only the amount of nitric acid consumed per batch. A batchwise Recycle flowsheet was also developed which uses an excess of 61% nitric acid, added continuously, with a 61% nitric acid recycle in addition to the aqua regia recycled to the dissolution step. A 6-in. ID continuous dissolver 9 ft high and a 4 in. ID chloride removal and feed adjustment tank were constructed and operated to verify flowsheet and equipment performance. (auth)
Research Organization:
Oak Ridge National Lab., Tenn.
Sponsoring Organization:
US Atomic Energy Commission (AEC)
DOE Contract Number:
W-7405-ENG-26
NSA Number:
NSA-13-008783
OSTI ID:
4293639
Report Number(s):
CF-58-11-82
Country of Publication:
United States
Language:
English