Separation of radioactive cesium from nuclear waste solutions

Abstract

An industrial-scale process utilizing hexacyanoferrate (K2CoFe(CN)6) ion exchangers in columns was developed for the selective sepn. of radioactive Cs (134Cs and 137Cs) from nuclear waste solns. The process was recently taken into operation at the Loviisa Nuclear Power Plant, Finland, where it has proved superior to all other Cs sepn. methods currently in use at nuclear plants. In the 1st full-scale test run, 253 m3 of low-level waste soln. was purified from Cs with only three 8-L ion-exchange columns, which means a vol. redn. factor of >10,000. In the sepn. process, the Cs radioactivity decreases to .apprx.0.05% of the initial radioactivity. Owing to its very low radioactivity, the residual soln. can be directly discharged into the sea. After exhaustion, the hexacyanoferrate columns will be placed and sealed in 1.7-m3 concrete containers, 12 columns in each, for final disposal in a bedrock repository. Introduction of the process has resulted in considerable savings in both waste management and disposal costs.