Determination of Total Rare Earth in HLLW by Spectrophotometry

In this paper, ⁹⁰Sr and ¹³⁷Cs were extracted into the organic phase from high level liquid waste(HLLW) by crown ether-calixarene crown ether in suitable acidic conditions. Then, U, Pu, Th, etc. were also extracted into the organic phase by TOPO-cyclohexane. The water phase was colored by chlorophosphonazo mA in suitable conditions in order to obtain the content of RE in HLLW. The extraction conditions  of ⁹⁰Sr and ¹³⁷Cs by crown ether-calixarene crown ether and that of TOPO-cyclohexane were investigated. The coloring conditions of chlorophosphonazo mA were studied and determined. The results show that ⁹⁰Sr and ¹³⁷Cs are extracted into the organic phase from HLLW by crown ether-calixarene crown ether in 4.5 mol/L HNO3, while RE are not extracted. The absorbance is linear with the quality of RE during the 0.10 mg/L at 670 nm. The relative standard deviation of RE in the simulated-HLLW is 2.3% (n=6), and the recovery rate is 89.9%-97.7%, while, the relative standard deviation of RE in real HLLW is 6.3%(n=3) using this method.