Facilities for near-surface disposal of radioactive waste are very important structures consisting of several safety barriers, and the substantiation and selection of the principal structures of near-surface disposal facility is a complex task that must be solved taking into account the distinctive specifics — the time of their active and passive operation, as well as the period of potential danger of radioactive waste.
The paper considers the main approaches to ensuring the long-term safety of near-surface disposal facilities through the use of various engineering safety barriers, measures to protect safety barriers, personnel, the public and the environment. To ensure safety, to prevent the spread of ionizing radiation and radioactive substances from the near-surface disposal facility into the environment, a systematization of safety barriers was carried out to ensure reliable isolation of the placed radioactive waste. Using the experience of building long-term structures, the periods of reliable isolation of the radioactive waste by each of the engineering barriers are indicated.
The safety barriers, which are included as the main engineered barriers in the design solutions of the near-surface disposal facilities being created, are consistently considered. Containers are the first engineered barrier. The second barrier is a buffer material based on the natural clays that fills the space between the walls of the modular structures and containers, as well as between the containers themselves. The third barrier is concrete walls, floor slabs and floor slabs of the modular structures of the disposal site. The fourth barrier consists of bentonite mats and a clay castle made of crumpled natural clay. The fifth barrier is a multi-layered covering screen constructed for waterproofing, protection from the atmospheric precipitation, ingress of animals, plant roots and inadvertent human intrusion. The choice of materials for the engineered barriers and the requirements for the characteristics of the barrier are carried out based on the long-term safety assessment calculations, including taking into account the properties of the host rocks.
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