The paper presents quantitative estimations of the effect of containers, matrix materials, bentonite barrier and hard rock massif on ecological safety during geologic isolation of longlived RW. The estimations were obtained on the basis of mathematical modelling of radionuclides (Np-237, Tc-99, Pu-239, Zr-93) migration in bentonite barrier, forecasting contaminated underground water migration in fractured zones, experimental data on leaching rates of radionuclides immobilized in boron silicate glasses and mineral-like ceramics. Preliminary data obtained at one of the sites of the Nizhnekansky massif were used in calculations. Is was shown that choice of optimum performances of multibarrier system can ensure safe final isolation of long-lived, not heat-generating RW fractions in geologic disposal located at 600 m depth.

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A huge amount of radioactive waste has been accumulated in the Russian Federation (RF) in the course of implementation of the defense and energy programs, industrial and research activity involving the use of nuclear materials. The most justified and technically feasible technology of solidified RW isolation is its disposition in low-permeable geological formations in specially constructed underground facilities. Today in Russia a Closed Fuel Cycle (CFC) has been adopted, at the CFC final stage the spent nuclear materials and radioactive waste have to be isolated from the biosphere for the whole term of their potential hazard. In Russia, in accordance with the regional approach to the decision of Radioactive Waste (RW) disposal problem, several candidate disposal sites have been assigned.

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