Advances in Modelling Salt Stock Deposition of Nuclear Wastes

Mingliang Xie and Helge C. Moog

GRS, Braunschweig, Germany

10th Annual GTT-Technologies Workshop

Herzogenrath, GermanyJune 4-6, 2008

Content

� Introduction

� Reactive Transport Modelling

� Reactions and Database

� Application – UO2(s) dissolutionand transport

� Outlook

Content

� Introduction

� Reactive Transport Modelling

� Reactions and Database

� Application – UO2(s) dissolutionand transport

� Outlook

Overburden

Biosphere

Host rock

?

?

?

Waste

Backfill

Solution

Aquifer

?

Of course, a real underground structure of a disposal site is

much more complex…This is just ONE base of an underground disposal site

� Red = BarriersGreen = solid saltBlue = crushed saltBlack = Disposal cavernGrey = Excavation-disturbed zone

� Up to 15 bases possible

Core

Bentonite Buffer

Fractured Rock

Shrinking

Heat Transport

Vaporisation

Condensation

WaterIntrusion

Contact

Mechanics

Mass TransportChemical Reactions

CoupledCoupled ProcessesProcesses in Geotech Systemsin Geotech Systems

ConceptConcept of of CoupledCoupled ProcessesProcesses

C T

MH

Temperature change →→→→Water/air storageWater/vapor/air/dissolved air transfer

Porosity Change →→→→Water/air storageWater/vapor/ions/air/ dissolved air transfer

Suction →→→→Stress/strain field

Ion exchange →→→→Stress/strain field

Temperature →→→→Stress/strain field

Chemical reaction →→→→Heat release/absorb

Porosity Change →→→→Heat conductionHeat storage

Temperature →→→→Chemical ReactionIon transport

Chemical Process →→→→Water/air/dissolved airtransfer

Water/air transfer →→→→Chemical reactionIon transfer

Disposal chamber for waste

Waste

Backfill

Solution

??

?

??

?

??

Thermodynamic Modelling

That is, what a safe disposal site looks like!

Many caverns form one system…

Interaction Waste - Solution

Equilibrium

∏∏ ⋅==j

jjj

jjjj maK

νννγ

Phasecomposition:

( )( )iiif

i

isolution

iPhases

ifisolids

mTGnG

GnG

γlnlnR,

,

++=

⋅=

⊗

⊗

∑

∑

Phase 1

Mm+

Nn+

Xx+

Yy+Thermody-

namic

equilibrium

Phase 2 Phase 3 Phase n

Aq. solutionWaste

Su

ffic

ien

tti

me

∑ ∑∑++=j j k

kjkjijjii mmmIDH ,,, )(ln µλγ

+ -

+ +

+ -

-

+ -

+

SIT -Single Ion Interaction Theory

Pitzer-Modell

� Approaches considering specific ionic iteractions …

Modells for the calculation of activity coefficients

� Debye-Hückel (1923): purely electrostatic interactions

� Extensions to the DH-equation…

Porosity/Permeability change

� Material microstructure � Dissolution/precipitation (C)

� Deformation (M,T)

� Swelling (bentonite)

� Permeability k=k(n)

PorosityPorosity –– permeabilitypermeability relationshiprelationship

(Clauser 2003)

Geochemical Geochemical processesprocesses

(Sonnenthal et al 2005)

Content

� Introduction

� Reactive Transport Modelling

� Reactions and Database

� Application – UO2(s) dissolutionand transport

� Outlook

GoverningGoverning EquationsEquations

n x conservative TransportChemical reactions with

PHREEQC, ChemApp or GEMS-PSI

i=1, 2,...,n

Saturated

GoverningGoverning EquationsEquations

(Suarez & Simunek, 1996)

Unsaturated

Geochemical simulators

GeoSys/RockFlow

CHEMAPP

PHREEQC

GEMS-PSI

RockFLow/GeoSys+ChemAppRockFLow/GeoSys+ChemApp

Old time step

New time step

Transport

Reaction

i=1, 2,...,n

ChemApp

Object-Orientation:Multifield Problems

PCS

MSH

GEO

GeometryPointsPolylinesSurfacesVolumesDomains

TopologyNOD NodesELE Meshes

IC BC ST

MATMFPMSPMMPMCP

NUM

FEMFDMFVM

FCT

I/O

CProcess::Create()CProcess::Config()CProcess::Execute()

EQS

Kolditz & Bauer (2004)J Hydroinformatics

2-D Ele men ts

3-D El eme nt s

1-D Ele men ts

T etrahedr a

Hex ahedraPri sm s

Tr iangles

Quadri lat erals

2-D Elements

3-D Elements

1-D Elements

Tetrahedra

Hexahedra

Prisms

Triangles

Quadrilaterals

Geometric Element Types

C6

C5

C4

C3

C2

C1

RnAn...B4nB1n

.....................

R4B4n...A4B24

R3...A3.B13

R2...B24.A2B12

R1B1n...B13B12A1

=

Dimension: (number of grid nodes * number of components)²

For real world applications: (105 * 20)² = 4*1012

Memory requirement: 4*1012

*

Multi-Componental Systems

PCS1

PCS2

EQS1

EQS2

IC1

ICPCS

ic_name:

PRESSURE1

NOD

ICList

BC .....

.....

.....BC1

BC2

bc_name:

PRESSURE1

bc_name:

PRESSURE1

BCList

TIM

MAT2MAT MAT3solid_property

solid_group1

: soil_property

soil_group1

:fluid_property

fluid_phase1

:

MATListMAT1

KER

FM ker_name:

FLOW1

KERList

OBJ2

OBJ

OBJ3

OBJ5

OBJList

OBJ1

OBJ4

ELE

PCSList

pcs_name:

FLOW1

pcs_primary_function:

PRESSURE1

pcs_name:

MASS_TRANSPORT1

pcs_primary_function:

CONC1

PCSExecute

Process()

PCSCreateProcess() PCSConfigProcess()

ker_name:

MASS_TRANSPORT

MTM IC2 ic_name:

CONC1

BC3 bc_name:

CONC1

PCSExecute

Process()

PCS Implementation

High Performance ComputingParallel Computing

Visualization

ParallelizationParallelization

In cooperation with HLRS Stuttgart

Verification example: Comparison with 1D PHREEQC

1D Transport and Cation exchange (Example 11, PHREEQC – User Instructions)

Flushing a 1D column with CaCl2.

Initial pore water: Na, K

Exchange: Ca-X2, Na-X, K-X

Ca = 6.0x10

Cl = 1.2x10

- 4

- 3

1 m/d

D = 0.002 m, n = 1.0, t=0.24 d C in mol/l

0.08 m

Cout

Ca = 0Cl = 0K = 2.0x10Na = 1.0x10

-4

-3

Ca-X2 = 0Na-X = 5.493x10K-X = 5.507x10

-4

-4

Verification Benchmark

Pore Volumes [-]

Co

nce

ntr

atio

n[m

ol/

l]

1 2 30.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

8.0E-04

9.0E-04

1.0E-03

1.1E-03

1.2E-03

Ca (RF) mol/lCl (RF) mol/lK (RF) mol/lNa (RF) mol/l

Verification Benchmark

Pore Volumes [-]

Concentr

ation

[mol/l]

1 2 30.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

8.0E-04

9.0E-04

1.0E-03

1.1E-03

1.2E-03

Ca (RF) mol/l

Cl (RF) mol/lK (RF) mol/lNa (RF) mol/l

Verification Benchmark

Pore Volumes [-]

Co

nce

ntr

atio

n[m

ol/

l]

1 2 30.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

8.0E-04

9.0E-04

1.0E-03

1.1E-03

1.2E-03

Ca (RF) mol/lCl (RF) mol/lK (RF) mol/lNa (RF) mol/l

Verification Benchmark

Pore Volumes [-]

Co

nce

ntr

atio

n[m

ol/

l]

1 2 30.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

8.0E-04

9.0E-04

1.0E-03

1.1E-03

1.2E-03

Ca (RF) mol/lCl (RF) mol/lK (RF) mol/lNa (RF) mol/l

Verification Benchmark

Pore Volumes [-]

Co

nce

ntr

atio

n[m

ol/

l]

1 2 30.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

8.0E-04

9.0E-04

1.0E-03

1.1E-03

1.2E-03

Ca (RF) mol/lCl (RF) mol/lK (RF) mol/lNa (RF) mol/l

Verification Benchmark

Pore Volumes [-]

Concentr

ation

[mol/l]

1 2 30.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

8.0E-04

9.0E-04

1.0E-03

1.1E-03

1.2E-03

Ca (RF) mol/l

Cl (RF) mol/lK (RF) mol/lNa (RF) mol/l

Verification Benchmark

PV

Co

nce

ntr

atio

n[m

ol/l]

1 2 30.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

6.0E-04

7.0E-04

8.0E-04

9.0E-04

1.0E-03

1.1E-03

1.2E-03

Na (PHREEQC) mol/lCl (PHREEQC) mol/l

K (PHREEQC) mol/lCa (PHREEQC) mol/lNa (RF) mol/lCl (RF) mol/lK (RF) mol/lCa (RF) mol/l

Verification Benchmark

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0.0009

0.001

0.0011

0.0012

0.0013

0 0.5 1 1.5 2 2.5 3

Pore Volume [-]

Co

ncen

trati

on

[m

ol/

l]

Ca (GeoSys)

Cl (GeoSys)

K (GeoSys)

Na (GeoSys)

Na (PHREEQC)

Cl (PHREEQC)

K (PHREEQC)

Ca (PHREEQC)

analytical solution

Concentrations at the column outlet

Cl

Na

K

Ca

analytical solution

Verification Benchmark

Content

� Introduction

� Reactive Transport Modelling

� Reactions and Database

� Application – UO2(s) dissolutionand transport

� Outlook

Cause of Database DifferenceCause of Database Difference

Example: Thermal Conductivity λλλλ of Liquid Toluene at 25oC

publication year (DDBST, 2006)

1D Benchmark

0.0002M calcite0.001M MgCl2

Verification Example

1D Transport and calcite dissolution

Simulated Program

-- MST1D (by Engesgaard and Kipp 1992)

-- PHT3D (by Prommer 2002)

-- GeoSys/PHREEQC (by Xie et al 2005)

0.0 0.5m

Simulation results comparison

D istance (m )

Cl(m

ol/kg

wa

ter)

0 0.1 0 .2 0 .3 0.4 0.50 .0E+00

2.0E-04

4.0E-04

6.0E-04

8.0E-04

1.0E-03

1.2E-03

1.4E-03

1.6E-03

1.8E-03

2.0E-03

C l (G eoS ys/C hem App)C l (G eoS ys/P H R E E Q C )

C l (P H T 3 D )

D istance (m )

pH

0 0.1 0.2 0.3 0.4 0.56.0E+00

6.5E+00

7.0E+00

7.5E+00

8.0E+00

8.5E+00

9.0E+00

9.5E+00

1.0E+01

1.0E+01

1.1E+01

pH (G eoS ys/C hem App)pH (G eoS ys/P H R E E Q C )pH (P H T3 D )

D istance (m )

Mg

(mo

l/kg

wa

ter)

0 0.1 0.2 0.3 0.4 0.50.0E+00

2.0E-04

4.0E-04

6.0E-04

8.0E-04

1.0E-03

1.2E-03

1.4E-03

M g (G eoS ys/C hem App)M g (G eoS ys/P H R E E Q C )M g (P H T3 D )

D istance (m )

Ca

(mo

l/kg

wa

ter)

0 0.1 0.2 0.3 0.4 0.50.0E+00

2.0E-04

4.0E-04

C a (G eoS ys/C hem App)

C a (G eoS ys/P H R E E Q C )C a (P H T3 D )

Simulation results comparison

Distance (m)

Ca

lcite

(mo

l/kg

so

il)

0 0.1 0.2 0.3 0.4 0.50.0E+00

5.0E-06

1.0E-05

1.5E-05

2.0E-05

2.5E-05

3.0E-05 Calcite (GeoSys/ChemApp)

Calcite (GeoSys/PHREEQC)Calcite (PHT3D)

Distance (m)

Do

lom

ite

(mo

l/kg

so

il)

0 0.1 0.2 0.3 0.4 0.50.0E+00

5.0E-06

1.0E-05

1.5E-05

2.0E-05

Dolomite (GeoSys/ChemApp)Dolomite (GeoSys/PHREEQC)

Dolomite (PHT3D)

Database Database sensitivitysensitivity analysisanalysis

Database Database sensitivitysensitivity analysisanalysis

X

Ion

icco

nce

ntr

atio

n(m

ol/kg

H2O

)

0 0.1 0.2 0.3 0.4 0.5-5.0E-04

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

Cl (YMF)Cl (NAPSI)

Ca (YMF)Ca (NAPSI)Mg (YMF)Mg (NAPSI)

Database Database sensitivitysensitivity analysisanalysis

Database Database sensitivitysensitivity analysisanalysis

Distance (m)

Min

era

lco

nce

ntr

atio

n(m

ol/kg

so

il)

0 0.1 0.2 0.3 0.4 0.50.0E+00

5.0E-06

1.0E-05

1.5E-05

2.0E-05

2.5E-05

3.0E-05Calcite (YMF)Calcite (NAPSI)Dolomite(ord) (YMF)Dolomite(ord) (NAPSI)

Content

� Introduction

� Reactive Transport Modelling

� Reactions and Database

� Application – UO2(s) dissolutionand transport

� Outlook

1D Benchmark

0.001M NaCl

Application Example

1D Transport and UO2(s) dissolution

Simulated Program

-- GeoSys/Rockflow+ChemApp (by Xie et al 2005)

0.0 0.5m0.01M UO2(s)

0.2 0.3m

Inert porous media

UO2(s) UO2(s) dissolutiondissolution and and transporttransport

Distance (m)

Dis

so

lve

dU

(M)

UO

2(s

)(m

ol/kg

so

il)

0.1 0.2 0.3 0.4 0.50

0.005

0.01

0.015

0.02

0.025

0.03

0

0.002

0.004

0.006

0.008UO2(s)

dissolved U

Initial

UO2(s) UO2(s) dissolutiondissolution and and transporttransport

Distance (m)

Dis

so

lve

dU

(M)

UO

2(s

)(m

ol/kg

so

il)

0.1 0.2 0.3 0.4 0.50

0.005

0.01

0.015

0.02

0.025

0.03

0

0.002

0.004

0.006

0.008UO2(s)

dissolved U

Xp

H,E

h0.1 0.2 0.3 0.4 0.5

0

1

2

3

4

5

6

7

8

9

pH

Eh

310 sec

UO2(s) UO2(s) dissolutiondissolution and and transporttransport

Distance (m)

Dis

so

lve

dU

(M)

UO

2(s

)(m

ol/kg

so

il)

0.1 0.2 0.3 0.4 0.50

0.005

0.01

0.015

0.02

0.025

0.03

0

0.002

0.004

0.006

0.008

UO2(s)

dissolved U

Xp

H,E

h0.1 0.2 0.3 0.4 0.5

0

1

2

3

4

5

6

7

8

9

pH

Eh

910 sec

UO2(s) UO2(s) dissolutiondissolution and and transporttransport

Distance (m)

Dis

so

lve

dU

(M)

UO

2(s

)(m

ol/kg

so

il)

0.1 0.2 0.3 0.4 0.50

0.005

0.01

0.015

0.02

0.025

0.03

0

0.002

0.004

0.006

0.008

UO2(s)

dissolved U

Xp

H,E

h0.1 0.2 0.3 0.4 0.5

0

1

2

3

4

5

6

7

8

9

pH

Eh

1110 sec

UO2(s) UO2(s) dissolutiondissolution and and transporttransport

Distance (m)

Dis

so

lve

dU

(M)

UO

2(s

)(m

ol/kg

so

il)

0.1 0.2 0.3 0.4 0.50

0.005

0.01

0.015

0.02

0.025

0.03

0

0.002

0.004

0.006

0.008

UO2(s)

dissolved U

Xp

H,E

h0.1 0.2 0.3 0.4 0.5

0

1

2

3

4

5

6

7

8

9

pH

Eh

2e4 sec

Content

� Introduction

� Reactive Transport Modelling

� Reactions and Database

� Application – UO2(s) dissolutionand transport

� Outlook

Outlook

� Implementation of coupled effect of volumetric changes due to chemical reaction on HM-behaviour

� Corrosion of HLW container and gas production

� Performance assessment: Application to real systems

� Paralel computing