The changes in the radionuclide transport regime of the Richard repository

The Richard repository is located in a subsurface area of a former limestone mine in Northern Bohemia. The institutional low- and intermediate-level waste has been deposited here since 1964. A post-closure safety analysis has been undertaken with the aim to examine the acceptability and radioactive waste capacity of the repository against the requirements of the Czech nuclear legislation was proposed. The concept of the final repository closure is the integral part of the safety analysis. A new proposal of the repository closure, a hydraulic cage safety concept, was also presented to eliminate the potential radiological consequences of a certain, critical scenario. The evaluating calculations of the former concept of the repository closure with one chamber in which hydraulic cage was implemented were performed. The calculations were carried out with group of critical radionuclides within the two variants of normal evolution scenario and critical scenario. The results validated high level of safety of the Richard repository given by its geological and technical conditions. According to the results, new proposals of the repository final closure were drafted and additional calculations of the repository source term were designed. (author)