Wellenberg (L/ILW repository)
Nagra proposes that the geological siting region Wellenberg (NW, OW) be placed in reserve for Stage 3.
The region in central Switzerland between the Engelberg valley and the Secklisbach valley is one of the six potential siting regions confirmed by the Federal Council for a deep geological repository.
Geological siting region Wellenberg for the L/ILW repository
Geographically, the siting region lies between the Engelberg valley (in the section from Grafenort to Wolfenschiessen) and the Secklisbach valley (Oberrickenbach). The east and west boundaries are defined by the limited overburden in the area of the Engelberg valley and the Secklisbach valley and the north and south boundaries by the limestones of the Drusberg and Axen nappes. After optimisation, the disposal perimeter comprises around 4.5 square kilometres on several levels.
|The geological siting region Wellenberg for a potential L/ILW repository with the optimised disposal perimeter and the siting area WLB-1 for the surface facility.|
Canton Obwalden: Engelberg
Canton Nidwalden: Wolfenschiessen
Results of the safety-based comparison in Stage 2
In the Wellenberg siting region for a L/ILW repository, the fractured host rock – the Helvetic Marls – has a restricted self-sealing capacity compared to the Opalinus Clay. Because of its lack of homogeneity, the barrier function is also less good than for the Opalinus Clay. The conditions for long-term stability are less favourable than those for the siting regions in Northern Switzerland. In particular, the conceptual models of geodynamics and neotectonics, but also the increased seismicity and the expected impact of erosion (topography, glaciation) are less favourable than in the other regions. Characterisation and exploration of the region are also difficult.
Nagra proposes that the Wellenberg siting region be placed in reserve for Stage 3.
Siting area identified for the surface facility
The siting area WLB-1 for the surface facility of a potential L/ILW repository in the Wellenberg siting region is located in the community of Wolfenschiessen on the flank of the Engelberg valley. It was identified by Nagra in September 2013 on the basis of collaboration with the region.
Next steps in the Sectoral Plan process
The proposals submitted by Nagra will be reviewed by the authorities and this will be followed by a public consultation process. At the end of Stage 2 – expected for 2018 – the Federal Council will decide which siting regions will remain in the process. These regions will then be investigated in more detail with 3D seismics and exploratory boreholes in Stage 3. Definitive site selection will be made in Stage 3, with the initiation of the general licence procedure as required by the Nuclear Energy Act.
In Stage 2, in January 2012, the Federal Office of Energy (SFOE) presented the siting area proposed by Nagra in the Wellenberg region. This proposal was discussed and evaluated as part of the regional participation process.
The regional representatives of the “Surface Facility Working Group” confirmed that the proposal fulfils the technical requirements, but noted that the identification of the geological siting region for construction of a repository was not accepted politically or socially. No additional proposals were made as part of the discussions.
Based on the cooperation with the Working Group and the siting Cantons, Nagra designated the siting area WLB-1 for the location of the surface facility of a L/ILW repository. The siting area for the surface facility lies in the community of Wolfenschiessen.
The decision of the Federal Council at the end of Stage 2 is expected for 2018. This represents the definitive decision as to which siting regions will remain in the process and will be further investigated in Stage 3. Collaboration with the remaining siting regions will continue in the coming years on the concrete design of the surface facility and the possibilities for optimisation; the results will be taken over into a possible general licence application.
|Geographical location of the siting area WLB-1 (surface facility for a L/ILW repository).|
Siting area WLB-1 for the surface facility
|Potential configuration of the components of the surface facility.|
|Orthophotograph of the Engelberg valley showing the siting area WLB-1. The area is located in the community of Wolfenschiessen on the flank of the Wellenberg.|
|Possibility for integrating the surface facility into the surrounding environment (photorealistic representation).|
In the Wellenberg siting region, the Helvetic Marls were investigated as a host rock for a low- and intermediate-level waste repository.
In the Wellenberg siting region, only the Helvetic Marls come into question as a host rock. These include the Palfris Formation, the Vitznau Marls of the Drusberg nappe, the Globigerina Marls and the Schimberg Shales of the Axen nappe. They occur as an accumulation and extend over the kilometre range in all three spatial directions, making the main contribution to the barrier function of the overall system. The adjacent formations (mainly carbonate rocks) make no notable contributions. In the Wellenberg siting region, the fractured host rock has a limited self-sealing capacity and homogeneity compared to the Opalinus Clay, resulting in a less good barrier function. The conditions for long-term stability are also less favourable in the Alps than in Northern Switzerland. In addition, the region is more difficult to explore from the surface.
|After optimisation, the disposal perimeter for a L/ILW repository at Wellenberg comprises around 4.5 square kilometres on several levels.|
|Geological profile from north-north-west to south-south-east through the Wellenberg siting region.|
Questions about the siting region
|2016 (22 March)||The SFOE publishes the Federal Office for the Environment’s review of the EIA preliminary investigations for the Jura Ost and Zürich Nordost regions.|
|2015 (30 Jan.)||The SFOE announces Nagra’s siting proposals. The geological siting regions Zürich Nordost and Jura Ost will undergo further investigation in Stage 3. They are suitable for a HLW, L/ILW or combined repository. The other siting regions will be placed in reserve. The proposals (safety-based comparisons, EIA preliminary investigations...) will be reviewed by the authorities, followed by a public consultation process. The Federal Council decision on Stage 2 is expected for 2018.|
|2014 (24 May)||Nagra presents the planning studies for the designated siting areas NL-2 and NL-6 for the surface facility at a full meeting of the regional conference for Nördlich Lägern.|
|2014 (15 May)||Nagra presents the planning study for the designated siting area ZNO-6b for the surface facility at a full meeting of the regional conference for Zürich Nordost.|
|2013 (4 Dec.)||Nagra presents the planning study for the designated siting area SR-4 for the surface facility at a full meeting of the regional conference for Südranden.|
|2013 (Sept.)||Nagra presents the planning study for the designated siting area JO-3+ for the surface facility at a full meeting of the regional conference for Jura Ost on 26th September. The planning studies for the designated siting areas in the regions Jura-Südfuss and Wellenberg are also presented in September. The planning studies for the other three siting regions will follow in the coming months.|
|2012 (20 Jan.)||Nagra announces its proposals for potential siting areas for the surface facility at a media conference held by the Swiss Federal Office of Energy (SFOE). These proposals serve as the basis for discussions within the framework of regional participation.|
|2011 (30 Nov.)||The Federal Council decides to include the geological siting region Jura Ost in the continuing Sectoral Plan process. Stage 1 of the process is complete and Stage 2 has been initiated.|
|2010 (1 Sept.)||Start of the public consultation phase on Stage 1 of the site selection process for deep geological repositories.|
|2010 (26 Feb.)||The Swiss Federal Nuclear Safety Inspectorate (ENSI) approves Nagra's proposed geological siting regions based on a review of safety and engineering feasibility criteria.|
|2009 (10 Dec.)||Announcement of the provisional planning perimeter by the Swiss Federal Office of Energy (SFOE).|
|2008 (3 Dec.)||Together with representatives of ENSI and Nagra, the SFOE provides information on the proposals for geological siting regions at an event in Stans.|
|2008 (25 Nov.)||Together with representatives of ENSI and Nagra, the SFOE provides information on the proposals for geological siting regions at an event in Engelberg.|
|2008 (6 Nov.)||Announcement by the SFOE of the proposed siting regions for deep geological repositories.|
|2008 (2 April)||The Federal Council approves the conceptual part of the Sectoral Plan for Deep Geological Repositories.|
|2002 (22 Sept.)||The voters of Canton Nidwalden reject the concession granted by the cantonal government for an exploratory drift at Wellenberg.|
|1998||Final report of the Wellenberg technical and economic working groups set up by the Department of the Environment, Transport, Energy and Communications.|
|1997||Suspension of the general licence procedure for the Wellenberg site by the Federal Council. Working groups set up under the lead of a steering committee.|
|1995||Completion of additional surface-based investigations at Wellenberg. Refusal of the Wellenberg concession application in a cantonal vote.|
|1994||Founding of the Cooperative for Nuclear Waste Management Wellenberg (GNW).|