Removal of Long-Lived Actinides from Purex Type HAW Raffinates. Development of Conceptual and Experimental Studies on Solvent Extraction

摘要

The experimental activity now being performed at Ispra J.R.C. laboratories on the chemical separation of actinides from nuclear liquid wastes is mainly devoted to the partitioning of high activity raffinates (HAW); low-acidity process flow sheets are being developed to this purpose. Basic assumptions are that 99.5% of U and Pu and <=90% of Np should be recovered during the conventional fuel reprocessing (PUREX PROCESS) and that the remaining actinide fraction should be removed from HAW raffinates by an additional process (partitioning). Waste decontamination factors assumed as preliminary target values are about 10 exp 3 for plutonium, americium and curium and about 10 for neptunium. Various theoretically possible alternatives for a new HAW management scheme, have been identified, in which waste partitioning is included. The results so far obtained from experimental tests performed on three types of organic extractants (HDEHP, HX-70, TBP) for partitioning purposes have been briefly mentioned. Two tentative flow sheets based on HDEHP and TBP have been proposed and discussed. Process steps in which particular problems arise and further investigations will be needed, have been pinpointed. (Atomindex citation 10:423986)