Comparative Quantitative Estimation of Engineered and Natural Barriers Influence on Ecological Safety of Long-Lived Radwaste Underground Disposal

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.