A de facto separation and concentration of fission products can be achieved by crystallization of bulk fission-product components, such as occurs during nitric acid recovery evaporations. In advanced reprocessing schemes, such as the Japanese NEXT process,56 this approach takes the form of an initial crystallization of uranyl nitrate. For cleanup of Hanford alkaline tank waste, proposed fractional crystallization of sodium nitrate achieves an equivalent result.57,58 Given that low concentrations of strontium are present in alkaline wastes, especially those with complexants, a useful decontamination can be achieved by isotopic dilution upon addition of strontium nitrate and result­ing precipitation of strontium carbonate.33 In the mid 1990s, the ITP process for cesium removal by precipitation with sodium tetraphenylborate was implemented at SRS.59 Owing to the insolubility of cesium tetraphenylbo — rate, an impressive decontamination of 1 Ci/L alkaline waste can be reduced to <10 pCi/L. However, due to the action of trace catalysts to accelerate tetraphenylborate decomposition, unexpectedly large benzene levels occurred in the tank headspace and led to shutdown of this process. A modification of the process, called the Small Tank Precipitation Process, was developed to overcome the benzene evolution by exploiting the induction period of the catalyst. The modified process was successfully demonstrated60 but has not been adopted for use.