ALTERNATIVE CONCEPTUAL DESIGNS OF SAFETY BARRIERS PROPOSED FOR DEEP RW CLASS 1 DISPOSAL AT THE YENISEISKIY SITE IN THE NIZHNEKANSKIY ROCK MASS

The paper presents initial data and a flowchart supporting the conceptual development of an engineered safety barrier system (EBS) intended for a deep disposal facility (DDF) for RW Class 1 (RW-1) to be established at the Yeniseiskiy site within the Nizhnekanskiy rock mass (NKM). It sets forth the key safety conditions that should be provided when a particular EBS material is selected under DDF designs. The study presents estimated sorption retention of non-mobile and migration of mobile long-lived RW-1 radionuclides in the porous solution of clay-based barrier materials. The study showed that under conservative assumptions (with no account taken of radionuclide retardation by bedrocks given their retention provided solely by the EBS) to provide NKM DDF safety, the clay-based barrier thickness should not be less than 1.5—2 m given the barrier material dry density of not less than 1.4 g/cm3 resulted from its saturation. As for the barrier material dry mass, it should not be less than 100–160 tones per single RW-1 package. The degree of conservatism may be decreased along with the growing knowledge on the protective properties of the rock mass and its consideration in further calculations of radionuclide migration.

Keywords: deep RW disposal, radiation safety, underground research laboratory, leaching of RW matrix, system of engineered safety barriers, pore and crack filtration, radionuclide migration, advective and diffusive transport, sorption retention, clay-based material, dry density, radioactive waste.

Martynov K. V., Zakharova E. V., Kulyukhin S. A. Alternative Conceptual Designs of Safety Barriers Proposed for Deep RW Class 1 Disposal at the Yeniseiskiy Site in the Nizhnekanskiy Rock Mass. Radioactive Waste, 2022, no. 2 (19), pp. 68—84. DOI: 10.25283/2587-9707-2022-2-68-84. (In Russian).