Interim storage of high-level radioactive waste will in several countries take longer than the originally planned few decades. Does the extended timeline of interim storage significantly change the input parameters for final disposal? Are there aspects that could previously be neglected but need to be re-evaluated for planning and implementing a deep geological repository (DGR)? Interim storage is structurally separated from the search for a deep geological repository in Germany, and the waste acceptance criteria for waste canisters still have to be defined. However, from the fundamental understanding of processes and geoscientific understanding, it may be possible to identify positive or negative aspects of inventory behaviour or technical measures during interim storage. Taking the requirements of final storage into account when considering extended interim storage offers the possibility of avoiding or minimising developments or changes in high-level radioactive waste during interim storage that may have negative influences on the safe confinement of the waste in a DGR.

In this workshop we want to link discussions regarding extended interim storage to the long-term safety of geological repositories. Aspects of the discussion could be as follows: does the embrittlement of the fuel cladding lead to difficulties in transportation and conditioning of the inventory? Could the decreasing thermal power of the inventory lead to temperatures that will negatively affect safety-relevant aspects? We are looking forward to a multi-faceted, interdisciplinary discussion that may go well beyond the given examples. Confirmed talks related to the workshop's topic will be given by Volker Metz (KIT-INE), Benedict Bongartz (IW University Hanover) and Florence Sentuc (GRS gGmbH). Following these introductory talks, we will discuss the given impulses and evaluate possible outcomes.