Dynamic Tests of Cesium-137 Recovery from the Mayak Model Alkaline HLW with p-Isononylcalix[6]arene-based Extractant

The article presents the results of studies on composition optimization, properties, and laboratory dynamic tests of extraction mixtures based on p-isononylcalix[6]arene for the alkaline HLW purification to remove ¹³⁷Cs. The distribution of ¹³⁷Cs among the products of the technological scheme is presented and the raffinate purification factor to remove ¹³⁷Cs are determined. It was revealed that, in the case of using nitric acid as a stripping solution, nitrosation of p-isononylcalix[6]arene is possible in the technological process. The composition of the resulting product was determined. To prevent nitrosation of p-isononylcalix[6]arene, formic acid was used in the stripping stage, which ensured stable operation of the extraction setup for 48 h while ¹³⁷Cs extraction from model alkaline HLW was at a level of 99.7%.