Retrievability of radioactive waste from a deep repository has received increasing attention during recent years. Arguments in favour are: more suitable sites might be found, future incentive for extracting valuable materials from the waste, or economically feasible way to transmute long-lived radionuclides to short-lived ones. The Member States have not included retrievability in their regulatory framework or in recommendations for disposal of waste. Two conditions govern the option to retrieve radioactive waste packages from a deep repository: the packages should not be damaged and the position of the package and the nuclide inventory must be known for the required time. As those two conditions can be met for a few centuries at the best, provisions for retrievability makes sense only for up to 300 years. Retrievability may be realised by keeping the access to the waste packages open through access shafts and the main galleries or by disposing the waste in a suitable overpack and abandon the repository after backfilling, closing and sealing. The objective of this study is to collect existing data on retrievability of heat-generating long-lived waste and to produce an un-biased set of data on implications in terms of cost when deciding adoption of a retrievability strategy.
- Present state of the retrievability option including regulations, recommendations and even opinions of national or international bodies. Attention will be paid to aspects of non-proliferation in the case of direct disposal of spent fuel being declared as waste.
- Overview of expected modifications as a consequence of opting for retrievability concerning design and fabrication of waste packages, design of the repository, operation and maintenance of the repository, surveillance and control of the installation and maintaining a documentation system up to retrievability. Evaluations with regard to radiation protection and long term safety to the environment will be made without carrying out detailed performance assessment calculations.
- Detailed evaluations for a reference disposal scenario under realistic conditions in comparison with a suitable deep underground repository.
- The Assumptions and boundary conditions will be defined and for the option of keeping the repository open and the "re-mining".
- Final disposal and retrievable storage concepts for each of the three host rock formations (clay, granite and rock salt) will be selected. Concise safety evaluations will be performed with regard to radiation protection and long term safety to the environment. Retrieval and re-mining concept for each of the three host rock formations will be selected. The total costs of each of the options selected will be evaluated.