. "Chemical Treatment of High Level Waste for Utilization." An International Spent Nuclear Fuel Storage Facility -- Exploring a Russian Site as a Prototype: Proceedings of an International Workshop. Washington, DC: The National Academies Press, 2005.
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An International Spent Nuclear Fuel Storage Facility: Exploring a Russian Site as a Prototype - Proceedings of an International Workshop
cal Association. Basic operation of the technology of separation of long-lived radionuclides involves the selective recovery from high-level waste of cesium, strontium, technetium, rare earth elements, and transplutonium elements, as well as the residues of uranium, neptunium, and plutonium remaining after the PUREX process. The objective of this presentation is to consider those developments that are now most feasible for application, are already in service at Mayak Production Association, or are soon to be introduced there.
FERROCYANIDE SORBENTS FOR CESIUM RECOVERY
An example of the successful use of sorption processes for recovery of radionuclides from high-level waste is the method of cesium recovery by inorganic ferrocyanide-containing sorbents developed by the Institute of Physical Chemistry in collaboration with Mayak Production Association.1 In practical application, preference was given to copper-nickel ferrocyanide, which has the highest stability in the cycle of sorption-desorption-regeneration. Systematic studies on the use of this sorbent enabled the development of technology for cesium recovery from high-level waste during SNF reprocessing. When testing the technology at Mayak Production Association, a 120 liter sorption column was used. The recovery degree of cesium at sorption stage was more than 98 percent; the cesium yield into desorbate was 98–99 percent; and the concentration ratio attained was 100 percent. After 15 cycles, the sorption properties of the sorbent remained unaffected. In the course of pilot industrial tests, about 7 millicuries of Cs were separated from high-level waste.
CROWN ETHERS FOR RECOVERY OF STRONTIUM AND CESIUM
A method using macrocyclic polyethers (crown ethers) has successfully been developed for strontium recovery from high-level waste. Specifically, an elaboration of the Institute of Chemistry’s technology using dicyclohexyl-18-crown-6 (DCH-6) was brought to the level of pilot industrial tests at Mayak Production Association. As a result of these tests, about 90 m3 of high-level waste were reprocessed and more than 0.5 mCi of radiostrontium were recovered with a sixfold degree of concentration.2 The degree of strontium recovery was 96 percent. A special advantage of the DCH-6 method is the simplicity and efficiency of conducting the strontium stripping operation using water.
RECOVERY OF CESIUM AND STRONTIUM USING CHLORINATED COBALT DICARBOLLIDE
Fundamental studies on the extraction of Cs and Sr by cobalt(III) dicarbollide have been carried out primarily in the Czech Republic. In Russia dicarbollide technology has been applied to high-level waste processing. Figure 1 shows the