Process for recovering boric-acid solutions that can be re-used in nuclear power stations from radioactive wastes and solutions arising in nuclear power stations

摘要

The invention concerns a process for recovering boric-acid solution that can be re-used in nuclear power stations from radioactively polluted technological solutions, liquid wastes, segregation waters or mixtures thereof, arising in nuclear power stations. In the process according to this invention, the solution (freed of suspended matter if necessary) is treated in a reverse-osmosis device, whose membrane retains at least 80% of the salts of the radioactive alkali and heavy-metal ions, but only has at most 30% salt retention for boric acid. Of the two solutions arising from this osmosis, namely the concentrate containing the majority of the radioactive substances and the permeate containing the majority of the boric acid and some alkali nitrate, the permeate is treated further in a reverse-osmosis device, whose membrane retains at least 90% of the alkali nitrates, but at most 40% of the boric acid. The concentrate arising in this stage is returned to the first reverse-osmosis stage, while the permeate is fed into a series of columns comprising at least two vessels connected in series and filled with macroporous, strongly alkaline ion-exchange resin in order to remove the residual content of alkali nitrate. The purified boric-acid solution, containing less than 0.001% by weight of alkali nitrate, is returned to the power station's boric-acid treatment system, and the concentrate is ... Original abstract incomplete.