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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
date
wa
ter
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nte
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rig
ht
do
wn
[%
]
3
3.5
4
4.5
5
5.5
wa
ter
co
nte
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left
up
[%
]
Water content right down [%]
Water content left up [%]
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