Physical and chemical problems of radioactive waste processing

The reduction in concentration was studied of soluble borates from radioactive wastes brought about by the precipitation of boric acid with cobalt(II) and iron(III) nitrates. Precipitation was carried out at various concentrations of boric acid, the precipitation agent and various solution pH. It was found that in the precipitation of soluble borates with Co(II) and Fe(III) ions, quantitative coprecipitation occurs of the radioactive cobalt, iron and strontium. The process may be described as isomorphic precipitation. Also investigated was the possible application of aliphatic alcohols and diols in selective extraction of boric acid from radioactive wastes. N-octanol and 2-ethyl hexanol appear to be suitable for practical use. The mechanism was studied of the extraction of boric acid and the synergic effect of anions on extraction with aliphatic diols. The association was evaluated of alcohols and their esters of boric acid, and a mathematical model was constructed for the evaluation of association constants from osmometric data. Also investigated was the suitability of inorganic sorbents and polymers for the fixation of radioactive wastes. It is concluded that water glass is none too suitable as the basic binding material because there is high leachability of soluble substances from polymer products. (Z.M.)