The TIMODAZ project – Main Issues -

introduction for the training course

Xiangling LiCoordinator of TIMODAZ project

EURIDICE

First Training Course: THM behaviour of claysin deep excavation with application to

underground radioactive waste disposal

Outline :

! Geological disposal concept ! Some examples of HLW repository designs

! Belgian design – Temperature evolution in NF! Swiss design - Temperature evolution in NF! French design - Temperature evolution in NF

! Main THM process around a repository : thermal impact on Host rocks

! EDZ observations in URLs – evolution at ambient T ! Thermal impact on EDZ and TDZ ?! TIMODAZ project presentation

Geological disposal of HLW & SF is a promising option in the world! Different Host rocks are under consideration:

! Clay formation : Belgium, France, Swiss, etc.! Granite : Germany, Sweden, China, Finland, etc. ! Salt : Germany ,

! TIMODAZ addresses the Clay formations! Belgium : Boom Clay => Plastic Clay! Swiss : Opalinus Clay => Indurated Clay! France : Callovo-Oxfordian Clay => Indurated Clay

90°

2 transport galleriesLength: 380 m Spacing: 400 m Inner diameter: 3.5 m

Connection galleryLength: 400 m Inner diameter: 2.0 m

Access shaftsHeight: 230 m

Inner diameter: 6 m

0

-185 m

-230 m(repository level)

-275 m

Clay formations for geological disposal of HLW ?

" suitable hydrogeological conditions : ! Very Low Kw, Transport limited to diffusion

only, etc. " suitable geomechanical conditions :

! Clay : self sealing/healing capacity! Suitable for excavation of a repository

" suitable geochemical conditions! Good retention, sorption capacity for

radionuclides" not a resource

Belgian URL : HADES

W EAntwerpen Mol Lommel

Water flow direction in the aquifer Leakage direction through the aquitard

BOOM CLAY

NEOGENE

repositoryF

F: fault area

SCK•CEN/F0521/IW/00/16

10 km

Dilution and dispersionDelaying the releasePhysical containment

Swiss : Mont Terri Rock laboratory

1: Mont Terri rock laboratory, 300 m beneath the hill2: Southern entrance of the motorway tunnel

French URL : Bure

Experimental drift Experimental drift

Technical drifts

Main shaftMain shaftAuxiliary shaftAuxiliary shaft

Technical drift

445 m

490 m

490 m

SMR1.1

SMR1.3

Main characteristics of three clays

Geomechanical characteristics Symbol Units Boom Clay(*) Callovo-OxfordianMol Mont Terri Zürcher Weinland Bure

Porosity n [-] 0.39 0.16 0.12 0.11 - 0.17

Hydraulic conductivity K [m/s] 2 × 10-12 / 4 × 10-12 8 × 10-14 / 2 × 10-13 2 × 10-14 / 1 × 10-13 < 10-12

Initial total stress, vert. σ v [MPa] 4.5 6-7 15.9 11

Initial total stress, horiz. σ H , σ h [MPa] ~4.5 (?) 2-3 / 4-5 22.6 / 15.1 11.0-15.4

Initial pore pressure u w [MPa] 2.25 1-2 6-7 4.5

Young modulus E' [GPa] 0.3 6 / 3 10.5 / 5 6

Poisson ratio ν ' [-] 0.125 0.24 0.27 / 0.25 0.3Uniaxial compression strength σ ' c [MPa] 2 10-16 30 / 6 24

Uniaxial tensile strength σ ' t [MPa] low 1 / 0.5 2.7 / 1.2 2.6

Cohesion c' [MPa] 0.3 3 / 1 7 / 1.5 8.5Friction angle φ' [°] 18 24 20-25 22

Notes 30 Myears old 180 Myears old 150 Myears oldNo cementation Some cementation (calcite) Cemented (calcite)

(*) values separated by / : value perpendicular / value parallel to bedding planes

Opalinus Clay(*)

Belgian repository design (Super container )

Temperature evolution ( Belgian concept)

0

10

20

30

40

50

60

70

0.1 1 10 100 1000 10000

Time (years)

Tem

pera

ture

incr

ease

∆∆ ∆∆T

(°C

)

1.60 m Interface Boom Clay/Liner

2 m

5 m

20 m

10 m

Top of Boom Clay

45 m 50 m below ground level

100 m below ground level

20 m below ground level

Source term : PC

1

10

100

1000

10000

1 10 100 1000 10000

Time after waste production (years)

Q (W

/m)

VHLM MOX55

30 y 50 y 80 y

Swiss repository design : Opalinus Clay

Near field temperature evolution ( Swiss concept)

Source term : I1

1

10

100

1000

1 10 100 1000 10000Time after waste production (years)

Q (W

/m)

45 y 60 y

French repository design : Callovo-Oxfordian Clay

Source term : I2

1

10

100

1000

1 10 100 1000 10000Time after waste production (years)

Q (W

/m)

30 y 40 y

Near field temperature evolution ( French concept)

pi decreases

σrσθ

pi

r

plastic or Damaged zone

Excavation / operational of the disposal gallery : => HM disturbance : EDZ, desaturation, etc. .

THMTHM coupled process in a HLW disposal system

-8

-6

-4

-2

0

2

4

6

8

0 10 20 30 40

distance from the axis (m)

σθ

σyσr

pw

plastic zone

elastic zone undisturbed

σ/pw

u u

Rad-waste disposal phase

Host-rock

Concrete

Backfill

Overpack

Steel lining

Concrete lining

Drainage, Saturation-desaturation… ∆∆∆∆Pw, ∆∆∆∆Pg

Dissipation of the heat

output from the waste : ∆∆∆∆T

(Super container)

Very complex THMVery complex THMcoupling

THMTHM coupled process in a HLW disposal system

∆T

∆H ∆Μ

Possible Thermal impact on Host Rocks

! direct coupling T####HM! thermal expansion of water! thermal expansion of solids

• thermal induced changes in stresses! Others

! Changes of hydraulic properties• viscosity of water decreases as T increases

! Changes of constitutive model parameter values• Properties/parameters are likely to be f(T)

! mineral alterations #### change of mechanical properties! porewater chemistry

HADES URL in Belgium

Excavation Damaged Zone (EDZ) : some examples

Bure URL in France

Excavation Damaged Zone (EDZ) : some examples

Excavation Damaged Zone (EDZ) : some examples

Mont Terri URL in Switzerland

EDZ evolution : Self - sealing at ambient T

2.0E-12

2.5E-12

3.0E-12

3.5E-12

4.0E-12

4.5E-12

5.0E-12

5.5E-12

0 2 4 6 8 10 12 14

Time (weeks)

Hyd

raul

ic c

ondu

ctiv

ity (m

/s)

Value 95% conf. Int. low 95% conf. Int.high

Sealing after floodingInitial discontinuity

0.0E+00

5.0E-13

1.0E-12

1.5E-12

2.0E-12

2.5E-12

3.0E-12

3.5E-12

4.0E-12

1 2 3 4 5 6 7

Time (weeks)

Hyd

raul

ic c

ondu

ctiv

ity (m

/s)

Value 95% conf.int.low 95% conf.int.high

0.0E+00

5.0E-12

1.0E-11

1.5E-11

2.0E-11

2.5E-11

0 4 8 12 16 20 24

Distance from gallery extrados [m]

k [m

/s]

R55D2004

R55E2004

R55D2005

R55E2005

EDZ evolution : Self - sealing at ambient T

In situ Kw measurement in HADES

10-11

2

4

68

10-10

2

4

68

10-9

2

4

68

10-8

Hyd

raul

ic C

ondu

ctiv

ity (m

/s)

10501000950900850800750∆t (d): time since 1. saturation

5

4

3

2

1

0Load Pressure (MPa)

01.05.2002 01.07.2002 01.09.2002 01.11.2002 01.01.2003

Left scale: Calculated hydraulic conductivity (m/s)Right scale: Load in MPa (red line)Bottom: T ime axes date and days after first saturation of boreholes(Test 10 = Selfhealing ExperimentTest 11 to 18 = Selfrac Experiment)

Test 10 Test 11

Test 12

Test 13

Test 17

Test 18

Test 16

Test 19

EDZ evolution : Self - sealing at ambient T

Mont Terri :

Long-term plate load

experiment

How this Damaged Zone evolves ?

" Dynamic problem ! Depending on the THM boundary conditions, ! operational phases of repository, open drift period,

" Thermal impact ?! T impact on EDZ ? ! T induces new DZ ?! Interplay with other influential factors ?

• Ventilation ? • Interaction with bentonite seal ?

$ Objectives of TIMODAZ project! Thermal Impact on the Damaged Zone Around a Radioactive

Waste Disposal in Clay Host Rocks

How TIMODAZ tackle these problems ?

! Three clays : Boom Clay, Opalinus Clay, COX ! State of the art on THM(C) (WP2)! New Laboratory tests (WP3) :

! Small to large scale! well controlled THM conditions ,

• suction and Temperature and stress controlled

• simulating the in-situ conditions! Input for the constitute laws building/calibration

! In-situ tests in URLs (WP4)! Small – large scale heater tests! DZ survey by means of different methods ! THM modelling validation

How TIMODAZ tackle these problems ?

Large scale heater test

How TIMODAZ tackle these problems ?

Large scale heater test

How TIMODAZ tackle these problems ?

! THM modeeling ( WP5 )! Constituve laws building/calibration based on the lab tests! Validation based on small scale in situ tests! Prediction of large scale in situ tests

! Significance of DZ in safety case ( WP6 )! WP7 : dessimination! End-users groups :

! TIMODAZ => needs of End-users

How TIMODAZ tackle these problems ? WP1: MANAGEMENT

WP6:

END USERSGROUP

ONDRAF / NIRAS

ANDRA

NAGRA

RAWRA

RATA

ARAO

WP3: LABORATORY EXPERIMENTS

WP3.1 WP3.2 WP3.3

THM CHARACTERIZATION

INPUT FOR CONSTITUTIVE LAW

MINERALOGIC CHANGES

INPUT THMC

SIMULATION TESTS &

INPUT FOR BENCHMARK

WP4: IN SITU EXPERIMENTS

WP4.1 WP4.2 WP4.3

THM SMALLLSCALE

THMCREPOSITORY

SCALE(PRACLAY)

LININGSTABILITY

UNDERTHERMAL

LOAD

WP7:

TRAINING

&

DISSEMINATION

WP5.1: CONSTITUTIVE MODEL WP5.2: BENCHMARK

THM LABORATORY EXPERIMENTS

SEALING PROCESS

CHEMICAL PROCESS AND THMC

Task 1 Task 2 Task 3

SMALLSCALEIN SITUTESTS

REPOSITORYSCALEIN SITUTEST

(PRACLAY)

WP2: DATA REWIEWPRIORITY SET UP FOR END USERS

Task 3Task 2Task 1

WP5: MODELLING

INPUT

FOR

DESIGN

SIGNIF ICANCE

OF

TDZ

IN

SAFETY

CASE