Final storage of radioactive scrap by vitrification - where liq. scrap contg. borates is converted into lead borate or borosilicate glass

摘要

Liq. scrap concentrates contg. borates, and with weak to medium radioactivity, are mixed with glass-making addns. using a max. ratio of 1:3. The mixt. is then heated to obtain a vitrifiable melt. Prior to the mixing operation, the liq. concentrates are pref. pre-dried to max. 5% residual moisture. Concentrates contg. B are pref. mixed with (1) 70 wt.% lead oxide, and melted at ca 600 deg.C. to obtain a lead borate glass; or (b) 50 wt.% silicates, esp. clay, and heated at ca 1000 deg.C to make a borosilicate glass. In either case (a,b), direct electric resistance heating is pref. used. Ion exchange resins contg. radioactive ions can be included in the mixt. Used esp. with scrap obtd. from pressurised water nuclear reactors, where 10 t/year of scrap can be obtd.