Dr. Piet Zuidema, Head of Science & Technology, Nagra:
30 years of the Grimsel Test Site - its contribution to the realisation of deep geological repositories in Switzerland
Dear partners, dear guests, dear colleagues
I would like to welcome you all here to Nagra’s underground research laboratory - the “Grimsel Test Site” (GTS) at around 400 metres below the surface, high up in the Swiss Alps. This small ceremony is dedicated to the celebration of 30 years of research at Grimsel.
I would like to open the celebrations by highlighting the last decades of the successful research performed here and its contribution to our national repository programme and by addressing the very valuable and mutually beneficial role of our international partners, which is exemplified in a new permanent exhibition to be opened today.
Nagra and its partners can look back at 3 decades of intensive underground research at the GTS – a period during which essential contributions have been made to the development and confirmation of safe geological disposal concepts for radioactive waste and a period in which significant advances towards the realisation of deep geological repositories have been accomplished. These include the selection and characterisation of suitable host rocks in our programme in Switzerland and elsewhere and further site selection and license applications in the programmes of some of our partners here – to mention but a few achievements. So we actually have more than one reason to celebrate.
Ingo Blechschmidt, Piet Zuidema and Stratis Vomvoris open the new exhibition at the Grimsel Test Site
Constructed between 1983 and 1984 in the crystalline formations of the Aar Massif formed some 300 million years ago in the Swiss Alps, the GTS is one of the oldest operating underground rock laboratories worldwide. Only a few underground test sites existed at that time and not much experience was available with building such a facility, especially as Nagra decided to construct the galleries using a tunnel boring machine in the hard crystalline bedrock. The local hydropower company KWO (Kraftwerke Oberhasli AG), with its extensive underground infrastructure, offered us one of its tunnels (Gerstenegg/GRIMSEL II) to enable access to the test facility. From the beginning, KWO has been one of our most important and highly reliable local partners, guaranteeing the safe operation of the test site, also when faced with the occasional technical and logistical challenges.
As a research facility, the GTS lends itself to carrying out a wide spectrum of geoscientific and engineering experiments.
One aspect of this breadth is the radiation controlled zone (IAEA Level B/C) located in one of the investigation galleries, which allows work to be performed with radioactive tracers in the geosphere under close-to-realistic boundary conditions (natural groundwater flow-field). With this unique set-up, it is possible to check the applicability of the results of small-scale laboratory experiments to a larger scale situation in a real rock environment deep underground in the Grimsel facility and to directly test model calculations of the migration of radioactive substances. I believe that it is not unreasonable to say that the experience gained and knowledge gathered are at the forefront in this field of research and, with the hydraulic flow-field in the experiment, unique in the world
Experience shows that repository projects can only be realised if we have confidence in the high level of safety offered and if they are technically feasible and find sufficient societal acceptance. Ensuring that the knowledge available worldwide is taken into consideration and integrated into these projects is essential and international cooperation is a key in realising this. Platforms where such cooperation can take place are a very efficient means of accomplishing this. The Grimsel Test Site was conceived as an open platform for international cooperation right from the beginning.
More than two dozen organisations and research institutes from twelve countries and the European Union have participated in the six phases of the research programme. Each phase has focused on the key issues at the time, attempting to anticipate the next steps in national programmes for the long-term management of radioactive waste.
The research conducted in underground laboratories complements conventional laboratory experiments, surface investigations and numerical modelling studies by bridging different scales and drawing links between laboratory set-ups and natural analogues.
We started with development of methodologies and tools suitable for characterising the geological, hydrogeological, hydrochemical and rock mechanical properties of low-permeability formations. Much practical experience was gained for the investigation of potential repository host rocks and sites and this was taken over directly into the design, implementation and interpretation of our field work. We benefited, for example, from all the pioneering work on rock characterisation using geophysical exploration methods such as seismic cross-hole tests, underground radar measurements, stress measurements and calibration of measuring probes, from the surface and from underground; and from the development of methods for hydraulic and gas testing and high quality hydrochemical sampling which we applied in the deep boreholes drilled as part of our exploration programme.
When I joined Nagra 30 years ago, the Grimsel facility was just coming into operation; a very exciting phase with a steep learning curve. At that time – as today – we benefitted greatly from the involvement of our partners and the strong team spirit among us all.
Then followed a phase dominated by performance assessment issues, in particular the testing and verification of models for radionuclide transport, the study of effects on the natural system due to the materials to be used in repository construction and investigations into the migration of repository-generated gas. I would like to use gas migration through the system of engineered barriers as an example of the contribution of the activities at Grimsel to our programme. With the knowledge gained here we have been able to design the Engineered Gas Transport System, one element of our repository sealing concept.
The past 15 years have been the age of engineering demonstration experiments. As the realisation of repositories draws closer, large-scale, long-term integrated experiments have become essential for raising technical and public confidence. As the focus of the Swiss national programme shifted from crystalline rock to sedimentary rock formations – namely the Opalinus Clay – our research programme has been designed to cover all aspects of the behaviour of the engineered barriers, engineering feasibility, impacts of construction on the host rock, repository operation, closure and monitoring. An example I would like to mention here is the behaviour of the bentonite surrounding the canisters, which we are studying in the FEBEX experiment that has been running since 1997.
But do rock laboratories have only a technical role?
I think they help not only in generating knowledge and experience, but also in explaining, demonstrating and making this knowledge available to our colleagues and transferring it from one generation of scientists to the next. The URL programmes foster synergies among disciplines, an essential factor for the success of long-term undertakings such as the implementation of safe deep geological repositories. An additional dimension to this is the broader public. By going underground and seeing geology and experiments one-to-one, the public obtains first-hand experience of waste disposal. Such visits are an excellent opportunity for dialogue between scientists and the public, helping society to develop a better understanding of waste management and disposal projects and enhancing their confidence in our work. To summarise, Grimsel is a unique platform for active interaction with the public and thus contributes significantly to the acceptance of the scientific and engineering work performed in the area of geological disposal. The range of visitors we have had in Grimsel is quite large and diverse; of course including many interested citizens, but in 1993 we welcomed her Majesty Queen Beatrice of the Netherlands accompanied by Mr. Adolf Ogi, a member of the Swiss Federal Council at that time, here at the GTS.
As I mentioned before, experience shows that repository projects can only be realised if they demonstrate a high level of safety, are technically feasible and find sufficient societal support. This means that we need to make use of the knowledge available worldwide and, consequently, that international cooperation is crucial. We use platforms such as Grimsel to address scientific challenges and to develop and test technological issues. Underground rock laboratories are ideal for this.
The Grimsel Test Site developed into a unique example of an open platform for international cooperation right from the beginning by focusing on technical issues and scientific questions of general interest. Through this it was possible to build long-lasting personal contacts and friendships beyond national borders.
Apart from projects related to the development of safe disposal concepts for radioactive waste, the underground rock laboratories are unique in bringing together a wide range of experience. We see today that a broader spectrum of technical and scientific investigations, for example in the area of geothermal systems or carbon storage and sequestration, could be conducted in facilities such as Grimsel. Together with our ever increasing cooperation with universities, I believe that these will be one of the additional key areas in the upcoming fourth decade of Grimsel.
To summarise, underground research laboratories such as Grimsel Test Site are important in bringing science and technology forward, are an ideal platform for international cooperation, a perfect place for ensuring knowledge transfer to the younger generation and can be extremely useful for communicating with decision-makers and the public.