Safety

The approach to the selection of sites for the construction of the Czech deep geological repository is in accordance with the Spent Nuclear Fuel and High-Level Waste Management Concept, i.e. in well-defined stages so that, in  terms of safety, the chosen site fulfils all the relevant domestic legislative requirements and international obligations applicable to the construction of the repository with a wide margin of error.

The suitability of the finally selected site for the repository must be confirmed by safety studies compiled for inclusion in the safety report as required by legislation, in particular the Czech Atomic Act (263/2016). The assessment of the safety of the radioactive waste repository both before and following closure must be based on an analysis of a range of scenarios defined by the identification of the various relevant features, events and processes that may affect its safety. In the case of high-level waste and waste with a considerable amount of long-lived radionuclides, we must consider a time-frame for proving safety in the order of hundreds of thousands of years. It is necessary to identify the features, events and processes of the normal development of the repository as well as those that might disrupt normal development including the probability of their occurrence (such as earthquakes or permafrost). This requirement cannot be fulfilled without having a detailed knowledge of the site at which the repository will be constructed, a thorough understanding of the processes that will occur within the disposal system and the compilation of conceptual, mathematical and computational models that describe and predict the development of the disposal system taking into account both the natural and the engineered barriers. In addition, all these models must be subjected to detailed validation and verification procedures.

Due to the wide variety of models envisaged, obtaining the full range of data so as to be able to demonstrate the safety of the deep geological repository requires a fully multidisciplinary approach. In 2014, SÚRAO launched a large-scale project aimed at acquiring the knowledge and know-how needed both to form an understanding of the various processes likely to occur within the repository system and to compile conceptual, mathematical and computational models describing the disposal system and predicting its development for safety assessment purposes. As part of this project, nine studies were conducted which were subsequently summarised in the form of safety reports on all the candidate deep geological repository sites. The reports contained all the knowledge available at that time for the assessment of safety. The geological, hydrogeological, transport, geomechanical and geochemical descriptive and predictive models were based on an analysis of foreign studies on this subject and new data obtained from geological research and survey work, laboratory experimentation and the Bukov Underground Research Facility. The studies will be updated to include the latest knowledge of the sites as the various milestones in the repository site selection process are reached. Moreover, the reports have been submitted for review to the regulatory authority, i.e. the State Office for Nuclear Safety. Together with the safety assessment reports, studies are also being compiled on ​​safety, feasibility and the impact on the environment according to the SÚRAO MP.22 document.

The safety and site assessment reports will be updated at all stages of the site selection process. Further research will focus on the preparation of more detailed geological, hydrogeological, transport, geochemical, thermal and geomechanical models and gaining a deeper understanding of all the features, events and processes that may affect the safety of the future repository.