GTS Information

Welcome to the Grimsel Test Site (GTS) Website

The Grimsel Test Site (GTS) located in the Swiss Alps was established in 1984 as a centre for underground Research and Development (R&D) supporting a wide range of research projects on the geological disposal of radioactive waste. International partners from Europe, Asia and North America are working together at this unique facility.

International Partners from around the world

Currently running projects at the GTS

Upcoming Events related to the GTS

6 May 2021: HotBENT - partner meeting (MS Teams)

22 - 23 September 2021: International Steering Committee (ISCO) Meeting, Switzerland



BASE (Federal Office for the Safety of Nuclear Waste Management), Germany has become a new partner in following projects: CIM, LTD and MaCoTe.

Grimsel's Role in International Underground Research & Development

The Grimsel Test Site is a research facility and not a potential repository site; although investigations may utilise a wide range of radioactive tracers, no radioactive waste will be disposed of at the GTS.

Grimsel Partners from around the world

NEW : High res virtual tour of the GTS. Older archives : Virtual Tours Archive.

Explore the GTS in a "street view" style point and click explorer.


Full-Scale Emplacement (FE) Experiment, Nagra participation in the EU project
Large Underground Concept Experiments (LUCOEX)

IFE Backfill Machinenvitation
to the presentation of the FE backfilling machine
on Monday 19th of May 2014 starting at 3pm and
to dinner in the evening, followed
by a one-day workshop on
bentonite material production & emplacement
on Tuesday 20th of May 2014
from 9am until approx. 4pm.

The presentation and workshop will be
held in the facilities of Belloli SA
in Grono GR, Switzerland

Please don't hesitate to contact Ms. Fankhauser (+41 56 4371 339 This email address is being protected from spambots. You need JavaScript enabled to view it.) if you have any further questions or require assistance.

We would be pleased to welcome you in Grono!
Herwig R. Müller (Nagra), PM of the FE experiment
Hanspeter Weber (Nagra), LUCOEX work-package leader

Supporting Documentation

The FE Experiment is a 1:1-scale heater experiment investigating the THM-coupled effects on the engineered barrier system and on the host rock (Opalinus Clay), which will be installed and run in the Mont Terri underground research laboratory.

Mont Terri Webpage :

FE Experiment - Backfill machine

Bentonite Block Pedestal Load Tests carried out at the Grimsel Test Site

FE Experiment - Bentonite Pedestal Load Tests at Grimsel    


Disposal : The Engineered Barrier System

A multi-barrier approach ensures the long-term isolation of radioactive waste and is the adopted solution of preference for radioactive waste management. The Engineered Barrier System (EBS) is one part of this passive multi-barrier system approach and it refers to all barriers introduced through technological (engineered) activities. It is complemented by the natural barrier, also referred to as the geological barrier or geosphere.

Most of the experiments running at Grimsel are focusing on using in-situ tests to analyse and characterise the near field of a nuclear waste repository. The near field includes the Engineered Barrier System (EBS) and the immediate rock surrounding a repository. In Nagra's concept, the disposal tunnels and caverns are placed deep underground (from around 600m) and in stable rock formations. Slightly different disposal methods are envisaged for the high level waste (HLW - spent fuel rods from reactors or vitrified waste) and the intermediate to low level waste (I/LLW - industrial waste). These two concepts are explained below.

Nagra's concept for an underground nuclear waste repository
Nagra's concept for an underground nuclear waste repository


1. High level waste (HLW) tunnels

The high level waste is contained within large steel disposal canisters.

These canister are placed on bentonite pedestals within the disposal tunnel at regular intervals, and the tunnel backfilled with bentonite.

Nagra's high level waste (HLW) disposal concept
Nagra's high level waste (HLW) disposal concept - cutaway

Nagra's high level waste (HLW) disposal concept - partly backfilled
Nagra's high level waste (HLW) disposal concept - partly backfilled


Grimsel experiments which are relevant to the high level waste (HLW) concept are :

2. Low level waste (LLW) caverns

Low level waste is contained within steel drums, and these steel drums are placed into concrete disposal casks, and filled with mortar.

The disposal casks are stacked into the low level waste disposal caverns which are lined with concrete. When full, the caverns are backfilled with mortar.

 Nagra's low level waste disposal cavern concept - cutaway

The low level waste (LLW) disposal cavern is shown below during the operational phase, and when it has been backfilled with mortar and sealed.

Nagra's low level waste (LLW) disposal concept
Nagra's low level waste (LLW) disposal concept - operational

Nagra's low level waste (LLW) disposal concept - closure
Nagra's low level waste (LLW) disposal concept - backfilled

Grimsel experiments which are relevant to the low level waste (LLW) concept are :

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.
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Grimsel Test Site : Videos and Animations

Browse our small library of films, videos and animations : Videos and Films


Grimsel Test Site : Brochures and Publications

View our online brochures and publications in our Media and Downloads section.