A new approach to radioactive waste self-burial using high penetrating radiation

The method of self-burial of radioactive waste in geological formations using direct heating of rocks by radiation is proposed in this paper. In the currently known studies, thermal conductivity is considered as a main heat transfer mechanism. Application of high penetrating gamma radiation for direct melting of surrounding rocks will reduce the energy absorption inside the sinking device and will lower maximum temperature and temperature gradients in the elements of the device. In this paper, conditions of realization of the direct heating by radiation mechanism are presented and requirements to heat-generating radionuclides have been derived. Assessments of the spatial distribution of energy release in the surrounding rocks for the point and plane sources with the radionuclide ⁶⁰Co have been performed. Based on these data, the temperature distributions in the surrounding rocks and the expression for determining the descent velocity as a function of ⁶⁰Co surface activity in the sinking device have been obtained. Estimations of energy absorption fraction inside the spherical heat-generating elements filled with ⁶⁰Co and surface activity of ⁶⁰Co, necessary to achieve velocity of about 1 km per year, have been made. The results are given for granite and salt rocks.