Methods for determining the amount of fissile materials in containers with liquid radioactive waste have been developed. The concentration of the sum of fissile materials (uranium-235 and plutonium-239) was determined by the method of plastic track detectors. This method is adapted to highly saline waters and bottom sediments. The contribution of plutonium-239 to the sum of fissile materials was determined by the radiochemical method. The methods were used to solve nuclear safety problems during decommissioning of NPPs.
