On the separation of cesium and strontium from oxalate filtrate by neutralization

At the treatment of HLLW (high-level liquid radioactive waste) by oxalate precipitation, the filtrate is occurred as a waste. But various elements including Cs and Sr are contained in the oxalate filtrate. It is very important, therefore, to separate from each other in a viewpoint of ultimate isolation of heat generating nuclides such as Cs and Sr from HLLW. In this study, the simulated oxalate filtrate, consisted of five elements (Cs, Sr, Ru, Fe and Mo) and organics (oxalic acid and ascorbic acid), was prepared, from which the separation of Cs and Sr was carried out by neutralization with NaOH. As a result, the simulated solution could be divided into Cs, Sr and Ru containing groups with pH. Sr was readily precipitated as froms of Sr (C2O4)*nH2O at pH 3. Iron and ruthenium were also co-precipitated around pH 8, and Cs and Mo remained in the resulting solution. (author)