SURFACE-CONTAMINATED METALS DEACTIVATING METHOD Russian patent published in 1997 - IPC

FIELD: nuclear power engineering, decontamination and deactivation facilities. SUBSTANCE: contaminated metal is treated at better temperature by water solution of borax and hydrofluoric acids with next it returning to processing after regeneration. Treated surface of metal is washed by water, which returns to deactivating solution without cleaning. Hydrofluoric acid concentration in deactivating solution is 1 - 4 weight %, and molar proportion of hydrofluoric to borax acid in mixture is 2.0 - 2.5. Treatment is carried out at temperature 40 - 80 deg C. Water solution regeneration is conducted either by electrodialysis method using or by method of sedimentation by oxalates or phosphates using, easier by filtration method by selective sorbent using or both methods combining. Two-cavity unit with cationite membrane is used for electrodialysis conducting, catholyte is separated from metal ions and radionuclides, then catholyte returns to cathode cavity of electrodialysis unit. Deactivation proceeds without bad-soluble fluorine-containing precipitations forming on metal surface. EFFECT: more effective method of metal surface cleaning. 4 cl, 1 dwg, 3 tb