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U.S. Department of Energy
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Development of an improved ion-exchange process for removing cesium and strontium from high-level radioactive liquid wastes

Conference ·

Processes are being developed to solidify and isolate the biologically hazardous radionuclides from approximately 23 million gallons of alkaline high-level waste accumulated at the Savannah River Plant. The waste consists mainly of a liquid supernate, a damp salt cake, and a gelatinous, insoluble sludge. The reference solidification process involves separation of the water soluble fraction (supernate) from the insoluble fraction, removal of cesium and traces of strontium from the supernate, incorporation of the sludge and the radionuclides from the supernate in glass, and incorporation of the residual salt in concrete. A new process, now being developed, involves sorbing cesium on phenolic resins that contain no strongly acidic sulfonate groups. These resins can then be eluted with formic acid which is not possible with Duolite ARC-359. Duolite CS-100, a phenol-carboxylate resin, was chosen for further development because of its greater breakthrough capacity and because it also sorbs strontium to some extent. Strontium sorption by CS-100 was not sufficient to eliminate the need for Amberlite IRC-718. However, the latter resin can also be eluted with formic acid because its functional groups are weakly acidic. Formic acid elution permits several options to be considered. The preferred option consists simply of mixing the eluate with sludge prior to calcination. Sodium formate, which is formed when the resins in the sodium form are eluted, decomposes rapidly between 450/sup 0/C and 500/sup 0/C and will be destroyed in either the calciner or the melter. The resulting sodium oxide would be incorporated into glass. The principal advantage of the new process is the elimination of a number of process steps.

Research Organization:
Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Lab.
DOE Contract Number:
AC09-76SR00001
OSTI ID:
6844407
Report Number(s):
DP-MS-80-65; CONF-801124-11
Country of Publication:
United States
Language:
English