Removal of ¹³⁷Cs from Dissolved Hanford Tank Saltcake by Treatment with IONSIV^® IE-911

Abstract:

This paper describes the removal of Cs from dissolved Hanford tank saltcake. A composite feed solution was prepared by dissolving archived saltcake samples from Hanford single shell tanks 241-S-101, 241-S-109, 241-S-l 10, 241-S-lll, 241-U-106, and 241-U-109 and adjusting the solution to approximately 5M Na⁺. This composite feed solution was treated by ion exchange with IONSIV® IE-911, which effectively reduced the concentration of ¹³⁷Cs to a point of negligible contribution to the overall sample dose. The reduction in sample dose was sufficient for subsequent testing of waste immobilization technologies without significant radiological hazard. Among the major identified species was K⁺, the principle cesium competitor in the ion exchange process, which was present at 0.01 M or about 550 times greater than cesium concentration. Ion exchange using IONSIV® IE-911 demonstrated high selectivity for cesium and quantitatively depleted ¹³⁷Cs from this feed, with an observed decontamination factor of greater than 30,000. The Cs-depleted saltcake solution also was characterized, and these results are compared to the initial characterization data when possible. As part of this characterization effort, the application of visible spectroscopy for quantifying major anionic components in tank waste was explored, and its potential as a means for directly measuring major bulk components in tank waste is discussed.