There is a deliberate time limit on interim storage licences

In the early 2000s, the Federal Office for Radiation Protection, the competent licensing authority at the time, deliberately limited the nuclear licences for the storage of nuclear fuels in interim storage facilities to 40 years. The Federal Office for the Safety of Nuclear Waste Management (BASE) is the licensing authority today. The time limit was based on the roadmap of a concept for an open-ended search for a repository site (AkEnd), which proposed the construction of an operational repository by 2030. The federal government made it clear that, although interim storage facilities provide the necessary protection for people and the environment for a limited period of time, they must not become final storage facilities.

The licence for the Gorleben interim storage facility (in German) is therefore limited to 31 December 2034, and the licence for the Ahaus interim storage facility (in German) is limited to 31 December 2036. The licences for the on-site interim storage facilities will expire in the 2040s.

As the original approach to the search for a repository site proved to be unfeasible, and following an interim extension of the operating lives of nuclear power plants, a second decision to phase out nuclear power in 2013 paved the way for the first open-ended, science-based, non-partisan site selection procedure. When the search for a repository site was resumed - with the aim of finding a site by 2031 - it was already foreseeable that licences would expire before a repository could be commissioned.

The German Bundestag must be involved

Several years after the start of the site selection procedure, a decision has now been pushed considerably further into the future (see information box: 'Timetable for the search for a repository site'). This means that high- level waste will have to be stored at interim storage facilities for a longer period of time. The need for longer interim storage raises a number of issues that need to be resolved in good time before the licences expire. However, even with extended storage, interim storage facilities are only a temporary solution. The best long-term solution is still a deep geological repository.

The legislator has considered the case of necessary longer interim storage and has provided for this in the regulation in Section 6, Paragraph 5, Sentence 2 of the Atomic Energy Act: The interim storage period may be extended in accordance with Section 6, Paragraph 3 of the Atomic Energy Act if there are "compelling reasons" and the German Bundestag has been "consulted in advance".

If there is an intention to extend the interim storage period

• the operators - for most interim storage facilities, this is BGZ Gesellschaft für Zwischenlagerung – must declare their intentions in writing at least eight years before the licence expires, or in individual cases at least six years before the licence expires;
• The public must be formally involved (BASE provides comprehensive information on all relevant procedures);
• All safety requirements must be reviewed according to the current state of science and technology.

Only when all requirements have been met will BASE authorise further storage at the interim storage facility.

Prolonged storage opens up new questions

Following many years of operation, BASE currently sees no indications of any safety deficits. However, the issues arising from longer-term storage in interim storage facilities need to be identified at an early stage:

• Can the safety of the casks and the interim storage facilities be guaranteed at the same high level as at present, even over longer operating periods?
• What are the technical and organisational considerations?
• In view of the phase-out of nuclear energy, there are also questions regarding the maintenance of expertise among the staff of the licensing and nuclear regulatory authorities, the authorised experts and the operators of the interim storage facilities.

Start of research activities

The operators of the interim storage facilities are primarily responsible for addressing these issues. BASE has also launched its own research activities with other stakeholders. The BASE research strategy and research agenda define the framework within which specific research projects are carried out. They enable BASE staff to evaluate future application procedures for storage licences based on the current state of science and technology.

Since April 2023, for example, two research projects have been running in cooperation with the Federal Institute for Materials Research and Testing on safety-related aspects of the casks during longer interim storage periods. The focus is on the metal seals of the casks.

An overview of further research projects can be found on the research page on the transport and storage of high- level radioactive materials.