Boreholes

Deep boreholes provide a direct insight into the underground geological environment and its structure.

Two drilling techniques are widely used:

In destructive drilling, the rock is crushed in the borehole. A fluid is pumped through the drill-pipe, which flushes the rock fragments (cuttings) to the surface. The drilling fluid is circulated in a closed circuit.

In cored boreholes, which are more costly to drill, hollow drill-bits grind only the rock at the edge of the borehole and the core in the centre remains intact. The core is loosened and pulled to the surface where the rock can be investigated in more detail.

The investigations are also supplemented by a range of borehole measurements - so-called logs - as well as hydrogeological and rock mechanical tests.

According to the Nuclear Energy Act, Nagra’s exploratory boreholes require a permit from the Federal Department of the Environment, Transport, Energy and Communications (DETEC). Nagra intends to submit the necessary in 2016. The federal authorities will review the applications together with the affected Cantons and communities. The decision of the Federal Council on Stage 2 of the Sectoral Plan is expected for 2018. Up-to-date information on the status of these exploratory boreholes can be found on the website "Tiefbohrungen" (in German).

To date, Nagra has drilled around 1000 to 2500 metres of borehole in Northern Switzerland as part of the investigation programme for the demonstration of disposal feasibility (Entsorgungsnachweis). The boreholes are:

Exploration applications

With a view to Stage 3 of the Sectoral Plan process, Nagra submitted applications for permits for eight exploratory boreholes in each of the siting regions Jura Ost and Zürich Nordost in September 2016. The applications for the Nördlich Lägern region followed in August 2017.

The applications were open for public inspection in the affected communities in the Jura Ost region between 27^th February and 28^th March. The inspection period in Zürich Nordost ran from 13^th March until 26^th April. The public inspection in Nördlich Lägern began on on 1^st November 2017. All public inspections were completed on 16^th January 2018. On 21^th August 2018, the first three permits (Bülach, Marthalen and Trüllikon 1) have already been granted by DETEC and others are expected in the coming months.

The planned exploratory boreholes in the Jura Ost region are Zeihen, Effingen 1, Riniken 2, Remigen 1, Remigen 2, Bözberg 1, Bözberg 2 and Effingen 2.

The planned exploratory boreholes in the Nördlich Lägern region are Weiach, Bülach, Stadel 1, Eglisau, Stadel 2, Glattfelden, Stadel 3.

The planned exploratory boreholes in the Zürich Nordost region are Uhwiesen, Laufen, Trüllikon 1, Trüllikon 2, Rheinau, Dachsen, Marthalen, Trüllikon 3.