Electrodialytic decontamination of spent ion exchange resins from CANDU primary heat transport purification circuits

Development of a novel electrodialytic decontamination process for the selective removal of radioactive Cs from spent Li form ion exchange resins from CANDU Primary Heat Transport (PHT) purification circuits is described. The process involves passage of a DC electric current through a bed of the spent ion exchange resin in a specially designed electrodialytic cell. The radiocaesium so removed from a volume of the spent resin is concentrated onto a much smaller volume of a Cs selective sorbent to achieve a significant radioactive waste volume reduction. Technical feasibility of the ElectroDialytic Resin Decontamination (EDRD) process has been demonstrated on a bench scale with a batch of simulated spent ion exchange resin and using potassium cobalt ferrocyanide as the Cs selective sorbent. A volume reduction factor greater than 10 was achieved. The process appears to be economically attractive. The EDRD process can also be effectively applied to in-line purification in the PHT circuits of CANDU reactors to minimize the volume of ion exchange resin usage. (author)