Stabilising radioactive residues contg. large amts. of boric acid - by mixing with water, sodium hydroxide, sand, cement and gypsum and forming into blocks

摘要

Process for stabilising highly radioactive wastes contg. boric acid, in the form of blocks which can be stock-piled, consists of mixing the residues with water, caustic soda soln., sand, cement and gypsum and moulding the mixt. into blocks. The proportions of the components of the mixt. are: boric acid (dry) 1.00; water 0.08; 45% NaOH soln. 0.25; sand 1.00; cement 0.80; gypsum 0.07. The radioactive residues are pref. obtd. by acidification causing the sepn. of boric acid and concn. and the cooling of the remaining liq. giving further pptn. of boric acid. Process allows blocks contg. large proportions of boric acid to be made, whereas existing processes give friable prods. if the boric acid content is >=5%. or blocks which do not resist lixiviation or blocks contg. =20% giving large vol. increase.