Decontamination of evaporator concentrates for cesium, strontium and actinides
Reprocessing operations produce medium activity liquid wastes, which are treated by evaporation; the distillate is discharged into the environment and all active and inactive salts are concentrated. The evaporator concentrates from retreatment plants must be stored in geological formations because of their high radioactivity from caesium, strontium and actinides. These elements, contained in the liquid acid wastes and with a high content of sodium nitrate, are removed by selective extractants using the technique of supported liquid membranes (SLM). The results obtained with synthetic concentrates are confirmed by experiment with real concentrates. The combination of a CMPO membrane and a DC18 C6 membrane made it possible to reach FD values higher than 150 for actinides, including trivalents. The DC18 C6 SLM resulted in a satisfactory decontamination for Sr (FD = 50), but it is noted that the concentration factor (CF = 32) must be raised while reducing the transfer of sodium across the membrane. TBB21 C7 fell far short of attaining the objectives set. Despite being highly selective, crown ethers do not produce a quantitative elimination of caesium (about 1.0 E-7 M) in 4M sodium nitrate solution; only 30% of the caesium was removed from the evaporator concentrate.
Bibliographic Reference: EUR 13887 FR (1992) 207 pp., FS, ECU 16.25
ISBN: ISBN 92-826-3391-8
Record Number: 199210328 / Last updated on: 1994-12-02
Original language: fr
Available languages: fr