INTEGRATED PROCESSING OF LIQUID RADIOACTIVE WASTES Russian patent published in 1998 - IPC

FIELD: radioactive waste disposal. SUBSTANCE: liquid radioactive waste containing cesium and strontium radionuclides is subjected to multistep processing: first in pretreatment stage optionally involving mechanical treatment, ultrafiltration, and microfiltration units; then waste is passed through selective inorganic sorbent based on ferrocyanides of transition metals (copper, nickel, cobalt) and porous inorganic carrier; and finally desalted and concentrated. The two latter operations are accomplished either by distillation or in a two-step process, first step involving electrical-membrane or reverse-osmosis desalting and second step electroosmotic distillation concentration. Desalting and concentration are conducted until 20 to 70 g/cu. dm of concentrate and 180-250 g/cu.dm brine are, respectively, obtained. Filtrates after desalting step are submitted to sorption afterpurification by passing them through one of the following sorbents: synthetic A-type zeolite, hexagonal-structure chabazite, and natural monoclinic-structure zeolite. Brines and exhausted sorbents are cemented in containers made in the form of 200 cu.dm barrels or reinforced-concrete 300-900 cu.dm. Exhausted sorbents can also be disposed being included in dry state into 3-00 cu.dm container. EFFECT: optimized process parameters. 14 cl, 1 tbl