Recovery of cesium from Purex plant wastes by metal ferrocyanides and ferricyanides II: Full level laboratory investigations

摘要

Laboratory scale experiments with synthetic Purex 1WW and HAW have demonstrated the feasibility of recovering cesium by precipitation with metal ferrocyanides and ferricyanides. One method for recovery of cesium involves neutralization of the precipitate ferric hydroxide and sodium diuranate, and recovery of cesium from the supernate by precipitation with zinc ferrocyanide. Another method involves precipitation with nickel or ferric ferrocyanide from partially neutralized 1WW, or from HAW. The second method yields a voluminous precipitate with low specific activity and poor radiochemical purity of the cesium, thus necessitating further purification and concentration of cesium before packaging. This can be accomplished by metathesis of the precipitate with sodium hydroxide and precipitation of cesium with zinc ferrocyanide. Other methods for recovery the cesium from metal ferrocyanides have been investigated by other workers. Several of the more attractive cesium recovery flowsheets have been demonstrated with synthetic solutions on the laboratory scale. To demonstrate the feasibility of cesium recovery from plant solutions, the effects of radiation and trace chemicals (such as corrosion products, fission products, and impurities in uranium and process reagents) must be determined. Therefore, the present work was performed with full-level Purex waste solutions, both 1WW and HAW.