Experts globally agree that repositories located in deep geological formations are the most suitable place for the disposal of spent nuclear fuel and high-level waste. It is expected that such geological formations, in combination with an engineered barrier system, will ensure sufficient isolation of the waste from the environment for tens of thousands to hundreds of thousands of years over which time the risk such waste poses to the environment will decrease to the natural level.
Certain conditions have to be fulfilled in order to develop such a deep repository. Adequate financing must be ensured, the technical aspects of repository construction and operation must be adequately addressed and, most importantly, the potential for the safe isolation from the biosphere of the materials disposed of must be proven beyond all doubt. Last but not least, the repository development project must be accepted by all the stakeholders, including the various relevant state authorities, local people and other concerned and interested parties.
Getting the timing of deep repository development and construction right is of great importance with regard to waste management as a whole. The correct management of spent nuclear fuel storage plays a significant role: the radioactivity of the waste and, consequently, the heat build-up decrease over time; as a result, requirements concerning disposal space and the design of underground disposal chambers are also lower. Furthermore, the storage period can be used to push forward the research and development of new advanced technologies which, it is hoped, will lead to a decrease in the overall amount and radioactivity level of the waste to be disposed of.
In addition to the pursuit of new technologies concerning spent nuclear fuel reprocessing, appropriate solutions for the repository’s engineered barriers are being developed and tested in a number of countries. Disposal containers with an isolating potential of hundreds of thousands of years have been designed and the properties of the various host rock types verified, such as granites, clays, salt or tuffs which are able to ensure the maximum level of water impermeability and thus reduce the potential leakage of radioactive substances from the repository into the surrounding environment. The information is gathered through extensive research in underground laboratory conditions conducted by specialists from a number of interested countries.
The Czech Republic plays an active role in such projects and utilises to the fullest extent the experience of other countries through extensive international cooperation.
A transparent environment which allows the public to be fully informed on repository siting and future construction has a significant influence on the trouble-free development and subsequent construction of a deep repository. Furthermore, providing the right level of motivation for those local communities involved in the repository development programme is a further important factor.