Grimsel Test Site

Mont Terri Project

Siting Studies for

Geological Repositories

Swiss URL’s

Underground Rock Laboratories and

their role in waste disposal programs

Grimsel Test Site (Phase VI) as a case study

Who is Nagra?

National Cooperative for the Disposal of Radioactive Waste

• Private co-operative of Swiss producers of radioactive waste and was founded

in 1972 by operators of the nuclear power plants (producing 40% of Swiss

electricity) - plus the Federal Government

• Located in the north of Switzerland, ca. 80 full staff positions

• Mission = development of Swiss repository projects for disposal of radioactive

waste, incl. corresponding research, i.e.

site exploration, repository design, site selection, safety assessment of two

geological repositories; operation/participation in two underground research facilities;

characterisation of inventory of Swiss radioactive materials

• ... within strong international co-operation based on bilateral & international

agreements as it is characteristic for the Grimsel Test Site (GTS)

In General:The GTS is an underground research facility

(rock laboratory) located in the Swiss Alps

A centre of excellence for underground Research

and Development (R & D) to support projects for

the disposal of radioactive and chemo toxic waste

and NOT a potential repository site

Situated in the crystalline rock of the central Aare massif. This is a fractured

granitic rock with saturated anoxic groundwater conditions

Geological profile of Switzerland

Comprises of 1.1km of 3.5 m tunnels dug with a TBM and blasted

24 years of research at this site investigating radionuclide migration, site

characterisation, demonstration of disposal concepts, gas issues etc

It includes an IAEA level B radiation-controlled zone, which allows in-situ

experiments with radionuclides – including actinides such as thorium,

uranium, neptunium, plutonium and americium

Grimsel Test Site (GTS)

GTS aims & concept

Why research in URL’s?

In simple terms, the procedure involved in realising a deep

repository for radioactive waste consists of the following:

- Characterisation of the host rock and the site,

- Demonstration of the feasibility (safety, engineering feasibility)

- Construction of the underground facilities

- Emplacement of the waste

- Monitoring prior to the repository closure

- Backfilling of the remaining tunnel sections in accordance with

strict quality assurance guidelines

Evolution of end-users needs

….reflected by the different phases of the GTS Project (Phase I to VI)

In principle, the role of a generic rock laboratory and selection of the experiments

to be performed in it depend on the status of a waste management programme.

GTS Evolution – ’Experimental techniques’

1997

1985

2005

GTS Evolution - International Cooperation

NAGRA

PSI

Uni Berne

ETH Zurich

Solexperts AG

ANDRA

BMWA

FZK

GRS

ENRESA

CIEMAT

CSIC

AITEMIN

RAWRA

NRI

HYRL

Posiva Oy

STUK

SKB

AIST

CRIEPI

JAEA

OBAYASHI

RWMC

NDA

EC

Status March 2007: 25

organisations from 9 countries + EC

The participation of several partner

organizations provided the expert resources

needed for complex, multi-disciplinary

experiments and projects and also allowed

costs to be shared.

Further develop and maintain know-how for key engineering issues like: handling, emplacement, monitoring and retrieval of high-level waste

Apply state-of-the-art science to validate key models over long periods (all waste types) by longer-term radionuclide retardation projects

Raise confidence and acceptance in key concepts prior to the repository licensing/construction by full-scale engineering projects

Act as a platform for scientific collaboration in the waste management community by providing access to a facility with flexible, open boundary conditions

Provide a center for training future generations of "nuclear waste"-experts (considering the needs of implementers, regulators and research organizations)

Provide an infrastructure for technical PR

Objectives for GTS Phase VI (2003 to 2013?)

GTS Phase VI Projects Overview

Status 2007:

- Full-scale HLW Engineered Barriers

Experiment (FEBEX / NF-PRO - EC)

- Gas Migration Test (GMT)

- High pH-Plume in Fractured Rocks (HPF)

- Long Term Diffusion (LTD)

- Colloid Formation and Migration (CFM)

- Colloid programme within FUNMIG (EC)

- Long-term Cement Studies (LCS)

- Low-pH Shotcrete Plug (ESDRED Module IV - EC)

- Test and Evaluation of Monitoring Techniques (TEM)

- CRIEPI‘s Fractured Rock Studies (C-FRS)

init

iate

d in

Ph

ase V

Projects initiated in Phase V already

(FEBEX, HPF, GMT)

FEBEX –Full-scale High Level Waste Engineered Barriers Exp.

Concept FEBEX

• Long-term project initiated in Phase V -> integrated in Phase VI

• Horizontal emplacement (HLW)

• Thermo-hydraulic-mechanical behaviour

• Scale 1:1

Heater installation (Oct. 96)

Continuation of the project in discussion at the moment.

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Concept GMT –

• Silo-type of emplacement

(SMA/LMA)

• Gas transport through EBS

• Scale 1:10

GMT - Gas Migration Test

GMT Silo Construction (Jan. 01)

Projects initiated in GTS Phase VI

Three “major” projects of Phase VI

Numerous in-situ experiments with inactive tracers and radionuclides

were successfully carried out over the past few years at the GTS. For

the GTS Phase VI, three major projects have been initiated to simulate

the long-term behaviour of contamination plumes in the repository near-

field and the surrounding host rock:

the Colloid Formation and

Migration experiment (CFM)

the Long-Term Diffusion (LTD)

the Long-Term Cement Studies (LCS)

1 Bentonite colloids

2 Radionuclides

3 – 6 Colloid interactions

7 RN matrix diffusion

8 e.g. organic colloids

is dedicated to study the generation of colloids from a bentonite-based EBS and to

investigate the influence of such colloids on radionuclide migration in a fractured

host rock under advective flow conditions.

The particular characteristic of CFM is that the flow field conditions will be closer to

repository relevant conditions than the preceding experiments at the GTS.

CFM - Colloid Formation and Migration

pH / Eh gradient and

erosion effects

Sedimentation

Absorption of

radionuclide

Nuclide

migration

Filtration

Groundwater flow

Attachment

Generation of colloid

CFM - principle layout of the in-situ experiment

sealed tunnel surface and

position of reinforcement

packer

colloids

Extraction

borehole (red)

Monitoring and

sampling boreholes

(green)

radionuclides

Surface packer

Emplacement borehole (grey)

with betonies/RN source (blue)

shear zone

Installation of the CFM reinforcement packer

CFM "yellow submarine“

LTD - Long Term Diffusion Project

- aims to obtain quantitative information on long-term, large-scale matrix

diffusion under in-situ conditions, and to characterise the pore space

geometry of rock matrix (in-situ porosity versus laboratory-derived data)

Penetration of solute across fracture flow-wetted surface, into the surrounding rock

Transport through connected system of pores or micro-fractures, deep into the rock matrix

LTD – WP 1: In-situ diffusion experiment

Demonstration of matrix diffusion in undisturbed rock as a geosphere retardation process

Verification and testing of current diffusion concepts and development of process-level models

Develop long term monitoring techniques and strategies

Radionuclide Half life Activity at t0 (MBq)

3H 12.35 a 88

22Na 2.602 a 4.2

131I 8.04 d 11.8

134Cs 2.062 a 4.2

LCS - Long Term Cement Studies Aims

to understand short- and long-term behaviour of grouting

materials and cements

to improve/adapt modelling codes and thermodynamic

databases developed for the use with hyperalkaline OPC

to improve the understanding of reaction kinetics and the

implications for PA

to develop applicable concepts for long-term in-situ experiments

under (more) realistic boundary conditions

Potentially:

to assess colloid production, emanation and transport behaviour in the repository near-field

to assess the influence of organic substances (e.g. superplasticisers)

to predict radionuclide transport over long timescales

LCS - Experimental Design for field tests

Cement injection /

Emplacement borehole

Monitoring

borehole

Recovery

borehole

Natural flow direction

Low pH

cement

Shear zone

A series of in-situ experiments with grout and pre-hardened OPC and

low-pH cements are planned (incl. hydraulic testing and tracer testing

prior to injection)

100 mm

250 mm

Groutplug

Groundwaterinjection

Technique

Uni Bern core infiltration method

(core under confining pressure;

hydraulic gradient to force advective

flow)

Use in-line and off-line analytical

techniques to detect high-pH

breakthrough (pH, EC, Na+, K+)

Use mylonitic granite and induce an

artificial fracture

Use a prefabricated grout plug

(traced with deuterium) and insert it

into the flow path

Experimental concept - Lab setup

LCS - Where are we?

Site characterisation and setup ongoing

Comparison of OPC and medium-pH grout done by Posiva

OPC properties investigated and compared with Posiva results

Technical feasibility of injection in the field tested on LCS06-01

Core for column experiment at University of Berne taken, cement block emplaced and experiment started

Desk study on CSH phases and comparison of available TDB‘s

LCS - Grout injection test

Projects at GTS initiated during the last year

ESDRED Module 4 - low-pH Shotcrete Plug

Test and Evaluation of Monitoring Techniques

ESDRED Module 4 –

Full scale demonstration of a low-pH shotcrete plug

Passthrough

borehole

Equipment

area

LOCATION

Aim: to demonstrate the support capacity of such plug under realistic conditions,that is with the swelling pressure of a bentonite buffer applied at one side of the plug.

ESDRED – Shotcrete Plug / Installation of Buffer

January 2007

Bentonite backfill emplacementHydration mats

February 2007

Long plug constructed using the shotcrete technique

March 2007 - ongoing

Start of saturation

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29.11.2006 24.12.2006 18.01.2007 12.02.2007 09.03.2007 03.04.2007 28.04.2007 23.05.2007 17.06.2007

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TEM - Test and Evaluation of Monitoring Techniques

The ESDRED plug experiment also provides the opportunity to test and evaluate

different monitoring methods in a situation which would have similarities with a

repository vault-end seal.

Three standard monitoring techniques are currently being tested at the GTS under

the TEM Project, namely:

- Conventional "hard" wired monitoring: this is part of the ESDRED experiment

- Wireless monitoring: data transmission technique from MISL combined with

Solexperts AG data acquisition systems supported by ANDRA and Nagra

- Non-intrusive techniques: tomographic techniques to monitor the EBS

development (e.g. saturation) from the geosphere are tested under the

leadership of NDA.

TEM - Components6

3

Wireless monitoring:

Magneto-Inductive (MI) technology

Conventionally wired monitoring:

ESDRED installationsNon-intrusive monitoring: seismic tomography

1 to 6 for source and receiver

http://www.grimsel.com

For the latest information on the Grimsel Test Site visit our website at:

http://www.grimsel.com