Concentrating radioactive effluent by multistage evaporation - with liq. inlet at late stage and condensate recycling to earlier stages

摘要

A method of concentrating by evapn. radioactive or similar liqs. utilises multistage evapn plants. The liq. is introduced into a stage other than the first stage of the plant, pref. into one of the last stages or the last stage here it is evaporated and the vapour flows back as condensate into an earlier stage of the process, where it is again evaporated and distilled to increase the purity of the discharged vapour. Pref. the vapour in the last stage is condensed, the condensate is then degassed and then it is conducted back to the earlier stage. If desired condensate from the earlier stage may be conducted forwards to the last stage where it is evaporated again. Used to obtain a sufficiently high degree of purity to satisfy the latest requirements of 10-8 Curie/m3 as compared with earlier values of 10-6 for residual activities. The method enables this high degree of purity in radioactive liq. effluent to be attained in an economical process requiring min. maintenance.