«The picture is coming together»

Nagra has completed drilling of the Marthalen borehole. Taking the results together with the information from the Trüllikon borehole, the earlier borehole in Benken and other investigations, the picture of the underground in the Zürich Nordost siting region is becoming more complete.

Since yesterday, the National Cooperative for the Disposal of Radioactive Waste (Nagra) has been working on dismantling the drilling rig in Marthalen. «In five months we were able to reach a drilling depth of 1100 metres and recover numerous rock samples. We are pleased with the results to date – the picture is coming together», says Philipp Senn, Nagra’s Deputy Division Head Collaboration Sectoral Plan and Public Outreach.

The rock samples will now be analysed in various laboratories to provide further information. The focus in all the boreholes is on the Opalinus Clay host rock in which the repository will eventually be constructed.

The results are consistent

Senn draws a positive initial conclusion: the Opalinus Clay in Marthalen is also over 100 metres thick, very tight and therefore suitable as a host rock for a deep geological repository. «The results to date from the boreholes in Trüllikon and Marthalen, the earlier borehole in Benken and other investigations give a consistent picture of the underground environment in Zürich Nordost siting region», adds Senn. «We are now seeing the bigger picture. At most, there are still details to be clarified», says Senn. Several laboratories are now analysing the rock samples from Marthalen.

Once the laboratory results are available, a decision will be made as to whether further boreholes are required in the in Zürich Nordost region. A borehole in Rheinau is currently under discussion. There are faults in the underground in this area, but it has not yet been decided whether the influence of these faults will be clarified with a borehole in Rheinau or otherwise.

The search for the best site is moving forward

The Federal Government has the lead in the site selection process for a deep geological repository. Based on investigations conducted previously, the three regions Jura Ost, Nördlich Lägern and Zürich Nordost have already been identified as suitable in principle for the construction of a repository. Nagra’s objective in drilling the deep boreholes is to find out which of the three regions is best suited. It is expected that, in 2022, Nagra will announce the region for which it will submit a general licence application.

Nagra has submitted a total of 23 permit applications for deep boreholes but has since withdrawn two of them. How many boreholes will actually have to be drilled in order to complete the overall geological picture depends on the results of ongoing work, but it is not planned to drill all the boreholes.

Nagra has set up a hotline for questions and concerns of local residents and other interested persons. It is free and operates 24/7 (0800 437 333).

More information: Patrick Studer, Head Nagra’s Media Office: 076 579 36 50, medien@nagra.ch

According to Swiss nuclear energy legislation, the producers of radioactive waste are responsible for its safe management and disposal. In 1972, the Federal Government and the nuclear power plant operators set up the National Cooperative for the Disposal of Radioactive Waste (Nagra) to perform this task. Nagra, which has its headquarters in Wettingen (AG), is the national technical competence centre in the field of deep geological disposal of radioactive waste.

Out of a strong sense of responsibility for the long-term protection of man and the environment, 130 employees are involved daily in performing this important work. The high level of competence is secured by targeted research programmes in two Swiss underground rock laboratories and intensive international collaboration.