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U.S. Department of Energy
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DAREX PROCESS: PROCESSING OF STAINLESS STEEL-CONTAINING REACTOR FUELS WITH DILUTE AQUA REGIA

Technical Report ·
DOI:https://doi.org/10.2172/4804847· OSTI ID:4804847

The Darex process developed for ihe recovery of U from stainless steel- containing reactor fuels consists of dissolution of the fuel material in dilute aqua regia, removal of chloride from the solution to prevent corrosion of downstream stainless steel process equipment, and adjustment of the nitrate solution to solvent extraction feed conditions. Each step can be either continuous, semi-continuous, or batch with continuous operation showing much higher throughput for comparable equipment. The preferred dissolvent is 5 M HNO/ sub 3/-2 M HCl, since dissolution rates and metal loadings are near maximum. Nitric acid from 60 to 95 wt% can be used in decreasing ihe chloride concentration to <350 ppm; ihe higher strength acids have process advantages. Excess nitric acid is recovered and recycled during produciion of a concentrated metal-salt solution, which is diluted io Purex solvent extraction feed acidity, 2- 3 M HNO/sub 3/. Titanium is a satisfactory material of construction, wiih corrosion rates

Research Organization:
Oak Ridge National Lab., Tenn.
Sponsoring Organization:
USDOE
DOE Contract Number:
W-7405-ENG-26
NSA Number:
NSA-16-020536
OSTI ID:
4804847
Report Number(s):
ORNL-2712
Country of Publication:
United States
Language:
English