Grimsel Test Site — Phase VI: Review of Accomplishments and Next Steps

Abstract

The Grimsel Test Site owned and operated by Nagra is located in the Swiss Alps (www.grimsel.com). The sixth Phase of investigations was started in 2003 with a ten-year planning horizon. With the investigations and projects of Phase VI the focus is shifted more towards projects assessing perturbation effects of repository implementation and projects evaluating and demonstrating engineering and operational aspects of the repository system. More than 17 international partners participate in the various projects, which form the basic organisational ‘elements’ of Phase VI, each one further structured in field-testing, laboratory studies, design and modelling tasks, as appropriate. Each project phase is planned with a duration of 3 to 5 years, to facilitate all practical and administrative aspects, ensuring flexibility for updating the overall plan with the recent findings. Scientific and engineering interaction among the different projects is ensured via the annual international meeting and ad-hoc meetings, as appropriate. As Phase VI approaches its mid-term point, a review of the accomplishments to date is performed to provide a sound basis for the detailed planning of the next steps. The accomplishments to date are described and assessed below; the opportunities with the on-going projects as well as new projects – currently under discussion – are also presented and discussed. The on-going projects include: studies of the long-term diffusion with emphasis on the processes in the rock matrix (LTD); colloid studies under in-situ generation conditions and migration velocities closer to velocities expected in an actual repository site (CFM); studies of the long-term cement interactions with natural systems (LCS); evaluation of full-scale engineered systems under simulated heat production and long-term natural saturation (NF-Pro/FEBEX); gas migration through engineered barrier systems (GMT); emplacement of shotcrete low-pH plug (ESDRED/Module IV); test and evaluation of monitoring systems (TEM). In addition, various shorter term projects assessing, for example, new geophysical investigation tools, wireless transmission, testing new tools and training for in-situ tracer transport studies have been performed and/or are planned for the near future.

Hydrologic issues associated with nuclear waste repositories

“…Construction of the facility in conjunction with a motorway tunnel started in 1987, and research activities of the Mont Terri project were initiated in 1996 with multiple phases. The current phase is Phase VI, which was defined in 2003 with a 10 year planning horizon, but has been extended to 2018 with an expanded scope [ Vomvoris et al ., ; Bossart and Thury , ]. This is shown in Figure , which also serves to illustrate the extent of a typical URL and the successive stages of activities conducted in such a facility.…”

“…The first is the so‐called HE‐E experiment [ Gaus et al ., ; Vomvoris et al ., ], which is being conducted in the Mont Terri URL. It is a heater experiment in the Opalinus Clay formation involving two heaters of 30 cm diameter emplaced in a 50 m long tunnel of 1.3 m diameter.…”

“… The HE‐E experiment layout at Mont Terri URL [ Vomvoris et al ., ] behavior of the clay and bentonite buffer system as both the near‐field rock and the bentonite buffer are gradually saturated with water. Construction of the experiment took place from December 2010 to June 2011.…”