RADIATION AND PROTECTIVE PROPERTIES OF CONTAINERS FOR NPPS’ SALT MELT CONDITIONING IN UKRAINE

Abstract

Considering that the problem of liquid radioactive waste management of Ukrainian nuclear power plants with WWER reactors is still unresolved, it is noted that the current level of scientific achievements provides grounds for creating a technology for the salt melt (SM) disposal without its processing. Since the exposure dose rate (EDR) for barrels with SM can significantly exceed the value of 5 mSv/h, the radiation-protective properties of the hypothetical packaging for conditioning of the salt melt formed by placing radioactive waste (RW) in a reinforced concrete container and its immobilization are considered. Exposure dose rate simulation was performed using the PHITS software package (Japan). The calculations were performed for a packaging consisting of 4 barrels of SM, placed in a universal protective container UZZK. Variants with different radionuclide composition of the SM, due to the duration of exposure of the SM – from 100% 137Cs to 137Cs-65%, 134Cs-15%, 60Co-20%, are considered. The specific concentration of radionuclides was taken from 5E7 to 1E9 Bq/kg. There are also 2 options for filling the voids: the first option involves filling the voids with the conditioning product of the bottom residue in the form of alkaline cement with a saline content of 25%, while the second option does not include radioactive salts in alkaline cement. The calculations showed the acceptability of the proposed conditioning of the salt melt by forming a package of 4 KRO-200 containers, universal reinforced concrete container UZZK TU U 29.2-26444970-005 and filling voids with the product of conditioning of the bottom residue in the form of alkaline cement with salinity -protective properties. A necessary condition for the implementation of practical measures for the conditioning of the salt melt accumulated in WWER reactors, followed by transfer to landfills is the corresponding changes in OSPU-2005 in terms of classification of the SM and its classification as solid radwaste.