METHOD OF REAGENT DECONTAMINATION OF SANDY SOILS FROM CAESIUM RADIONUCLIDES

摘要

FIELD: ecology.;SUBSTANCE: method of reagent decontamination of sandy soils from caesium radionuclides involves treatment of soils with water solution containing decontaminating reagents which include sulphuric acid with concentration of 2-4 M at ratio of liquid and solid phases of 0.5/1-1/1 in autoclave at temperature of 100-140°C, with further separation of water solution with decontaminating reagents from cleaned soil; after that, caesium radionuclides are extracted from separated water solution with decontaminating reagents by supplying to the above solution of ferrocyanide of alkali metals or ammonium till the concentration is 6·10^-4÷7·10^-2 M with formation of deposit. Treatment of fine fractions is performed in autoclave at ratio of liquid and solid phases of 2/1-3/1. Some portion of reagent solution (1/2 at ratio of liquid and solid phases of 2/1 and 2/3 at ratio of liquid and solid phases of 3/1) is moved by means of decantation to precipitator in which caesium radionuclides extraction is performed. Reagent solution is supplied back to autoclave, mixed with the rest reagent solution and fine fractions, and that operation is performed for 2-3 times. Sulphuric acid is added to reagent solution till original concentrations, and stage of reagent treatment is repeated at the same parameters. Determination of specific caesium activity in fine fraction is performed; if contamination level corresponds to sanitary regulations, reagent treatment is stopped.;EFFECT: invention allows increasing soil decontamination coefficient for their cleaning till the level of sanitary regulations.;1 ex, 1 tbl