Geological and radioecological problems of the objects formed by peaceful nuclear explosions – special radwaste repositories

Abstract

An assessment of the present status of sites used for peaceful underground nuclear explosions on the territory of the Russian Federation is given. The desirability of recognizing the central zones of nuclear explosions and surface repositories formed near them for storing special radwastes is substantiated. It is shown that formation water is the main substance for removing technogenic radionuclides to the Earth's surface as well as upper-lying water-bearing levels. Data are presented on the present radio-ecological status of the territories of peaceful nuclear explosions and their possible classification according to the degree of radiation safety.Eighty one of the 125 underground nuclear explosions conducted in the USSR from January 1965 to September 1988 for peaceful purposes were in Russia. The explosions and the implementation of the nuclear explosion technologies were requested by eight industry ministries. The Ministry of Medium Machine Building performed the planning work, delivery and detonation of the nuclear device, and secured seismic and radiation safety. The Leading Design and Research Institute of Industrial Technology (VNIPIpromtekhnologii) was the head planning and scientific-research organization concerned with introducing nuclear explosion technologies into the national economy and continues to investigate radiation conditions and plan rehabilitation measures on the territories of previous explosions [1][2][3][4][5].The central zones of the peaceful nuclear explosions are sections of the deep interior of the Earth which were subjected to mechanical, thermal and radiation action and contain radioactive substances formed as a result of the explosions. Analysis of the computational and experimental data shows the following: 1) at the present time and in the near future (70-90 yr), the 90 Sr, 137 Cs, and 3 H formed from the parent inert radioactive gases will determine the activity of the rocks in all objects formed by peaceful nuclear explosions;2) the rock in the collapse column and the melt in the central zone of the explosion will remain solid radwastes for 120-300 yr with respect to the level of contamination with these radionuclides; and3) for some objects formed during the explosion, the melt contains plutonium isotopes and should comprise solid α-containing wastes for several hundreds of thousands of years (Table 1) [6].Since, as a rule, the rock contains water and/or liquid hydrocarbons, formation fluids begin to fill the central zone of the explosion (cavity, collapse column, and adjoining crush zone). Depending on the formation porosity, the time required to completely fill the cavity and collapse column can range from days to several years. The entering water cools the central zone of the explosion and simultaneously comes into contact with the cavity melt and the contaminated surface of the rock