イオン交換による放射性廃液の処理

抄録

The process treating radioactive liquid wastes by ion exchange has been widely adopted, alone or combined with another sort of processes, especially when the wastes contain rather low concentration of electrolytes, for which the decontamination factor is rather high by this process, even with lower treatment cost, in comparison with the others.
(1) Among various ion exchangers, inorganic one is more economical for this purpose than organic one, if no regeneration of the exchanger is practised in the process.
(2) The coprecipitation method and pH control are added properly to the process with cation exchangers, of which selective characteristics can remove some of specific nuclides in the wastes, very effectively.
(3) The desalting systems in combination of cation and anion exchangers in a two-bed or a mixed-bed give higher decontamination factor, while the ion exchange membrane can treat highly concentrated wastes more economically.
(4) In general, low level wastes can be treated reasonably with cheaper cation exchangers only, with the coprecipitation method.
(5) The decrease of the exchange capacity by strong radioactivity is especially remarkable on anion resins.
(6) Quite a few studies have been performed to remove radioactivity in the wastes by soils or soil forming minerals, with their ion exchange capacity. Furthermore, by utilizing such a natural capacity of soils, the wastes have been directly disposed into the ground.
In this paper, the past history, the present status and the future prospect on the treatment of the wastes by ion exchange process are reviewed, summarized and discussed in the six categories as stated in the above.