The site for the deep geological repository

Radioactive substances are used in nuclear power plants and in medicine, industry and research. Radioactive waste is produced in the process and the waste producers are legally obliged to dispose of it safely. For decades, national and international experts have searched for the best solution to safely contain radioactive waste over a period of hundreds of thousands of years until it is no longer hazardous. Deep below the surface, time practically comes to a standstill, which is why there is broad consensus that deep geological disposal is the best solution. Switzerland has anchored the requirement for a repository in its legislation.

Nördlich Lägern is the most suitable site and has the largest safety reserves. This has been determined based on three key factors: 1. Here, the rock deep below the surface best confines the radioactive waste. Nagra detected traces of water dating back millions of years in the pores of the rock. The quality of the rock is highest here. 2. As it is extremely stable, the rock in Nördlich Lägern is best suited for confining the waste not only today but also in the distant future. The earth's surface will change over time, but the ground deep below the surface will not. The rock hosting the repository thus offers the highest protection here. 3. Nördlich Lägern has the largest area of suitable rock, providing Nagra with the greatest degree of flexibility for constructing the repository.

1. It is very tight. 2. Should fissures form in the Opalinus Clay, it can seal these itself as it swells on contact with water. This has been demonstrated in numerous experiments. 3. The Opalinus Clay can bind radioactive substances over long periods of time. It contains negatively charged platelets. Most radioactive substances in the waste are positively charged and therefore effectively stick to the Opalinus Clay, which prevents them from migrating through the rock.

In 2015, we were concerned that, based on limited data available at the time, constructing the repository in Nördlich Lägern would be more challenging from an engineering perspective. The Swiss Federal Nuclear Safety Inspectorate (ENSI) criticised that these concerns were not sufficiently supported by data. As a result, we investigated all three regions extensively. Our conclusion: it is possible to construct a safe deep geological repository in all three regions. From today’s point of view, Nagra’s initial assessment was too cautious.

The total cost for decommissioning and waste management will amount to CHF 23 billion. Of this, around CHF 3.5 billion will be used for the decommissioning of the nuclear power plants and the interim storage facilities. The remaining roughly CHF 20 billion are allocated for work in conjunction with the deep geological repository such as research, interim storage, construction and operation.

Nagra was tasked with proposing the safest site for a repository based on scientific and technical expertise. Discussions concerning compensation payments and measures do not fall under Nagra’s responsibility but under that of the radioactive waste producers.

The surface infrastructure will cover an area of just over 12 hectares. This is equivalent to around 24 football fields.

By placing the encapsulation plants at Zwilag in Würenlingen, we can make use of synergies with existing facilities. The site is already the competence centre for the conditioning and packaging of radioactive waste. Environmental aspects have also been considered: less forest will have to be cleared and less soil removed.

After decades of research, we will enter a new phase in the project of the century of deep geological disposal. We will prepare the general licence applications for submission in 2024. These will then be reviewed by the authorities. The decision to approve the licences will be made by the Federal Council and the Federal Parliament and, in case of an optional referendum, the Swiss voters. At least a further ten years will pass before the start of initial construction work.