Used Nuclear Fuel Disposition R&D

International Collaboration Activities in

Disposal R&D:

Relevance to R&D Priorities in Roadmap and

GDSA model

Jens Birkholzer and Liange Zheng

Energy Geosciences Division

Lawrence Berkeley National Laboratory

Mont Terri Project

– Participate in experiments at Mont Terri clay URL

in Switzerland

DECOVALEX Project

– Participate in model comparison initiative for

several URL related tasks in different host rocks

Colloid Formation and Migration Project

– Participate in colloid research at Grimsel granite

URL in Switzerland

FEBEX DP

– Participate in FEBEX dismantling project, which

evaluates bentonite-rock behavior after 18 years of

heating

SKB Task Forces

– Participate in crystalline rock research centered

around Äspö HRL in Sweden

Nuclear Energy Agency (NEA)

– Thermochemical Database Project

– Salt Club

– Clay Club

HotBENT

Disposal R&DCurrent Portfolio of International

Partnerships/Activities

2

US-Republic of Korea (ROK)

– Participate in KAERI Underground Research

Tunnel (KURT) experiments in crystalline rock

– Joint Fuel Cycle Study (JFCS), information

exchange in used fuel disposal

US-Germany Salt Collaboration

– Participate in testing and modeling studies for

thermal-mechanical and hydrological behavior of

domal and bedded salt

US-Sweden COSC Collaboration

– Participate in testing hydrogeological

characterization methods for deep boreholes

US-China

– Bilateral Civil Nuclear Energy Cooperative Action

Plan (BCNECAP) with working group in Spent Fuel

Storage and Repository Science

Other Potential Opportunities

– Explore use of existing Memorandum of

Understanding (MoU) between DOE and Spain

(ENRESA), France (ANDRA), Japan (JNEAP) and

Belgium

Multinational Initiatives Bilateral Research Collaborations

3

International Activities supporting GDSA

International activities is supporting GDSA via:1. Facilitating the development of reference cases

2. Deepening the scientific understanding of key processes

3. Improving process models

4. Supplying GDSA with well-tested constitutive relationships that govern

the evolution of key parameters such as porosity, permeability, clay

mineral alterations

5. Establishing a large database which could be used to validate GDSA

models

International activities cover a variety of key R&D issues related to

argillite, crystalline, salt host rock, EBS, the focuses have been:1. Coupled processes

2. Interfacial areas (canister/EBS, EBS/host rock)

3. Long term goechemical alteration

4. Flow and radionuclide transport

4

Extensive characterization of the

initial state bentonite

Monitoring temperature, relative

humidity, stress, pore pressure at

various locations throughout the

entire test duration.

Chemical characterization of EBS

after two dismantling events

Characterization of interfacial area:

canister/bentonite,

bentonite/concrete,

bentonite/granite

Characterization of corrosion and

microbial processes

FEBEX-DP at Grimsel Test Site

Partial dismantling in 2002

Heating started in 1997

Final dismantling in 2015

5

DOE Activities Associated with FEBEX-DP

Coupled THMC modeling of FEBEX-DP provides GDSA with

1. Right processes that control the saturation of bentonite

2. Evolution of porosity, permeability as a result of hydration and swelling

3. Chemical environment (e.g. pH, Eh, etc) during the saturation phase

4. Long term mineralogical alteration of bentonite

5. Structural and mineralogical change at the interfacial areas

-1

0

1

2

3

4

5

6

0 2000 4000 6000 8000

No

rmal

Str

ess

(MP

a)

Time (day)

E2 data, r=0.5 m

THMC model

0

5

10

15

20

25

30

35

40

0.4 0.6 0.8 1 1.2

Wat

er c

on

ten

t (%

)

Radial distance (m)

Data 5.3 yrs

Data 18.3 yrs

THMC-LS, thermal osmosis, 5.3 yrs

THMC-LS, thermal osmosis, 18.3 yrs

hea

ter

gran

ite

0.0E+00

2.0E-01

4.0E-01

6.0E-01

8.0E-01

1.0E+00

1.2E+00

0.4 0.6 0.8 1 1.2 1.4

Co

nce

ntr

atio

n (

mo

l/L)

Radial distance (m)

Cl-

data S29,S28,S19, 5.3 yrs

Sq data, S47, 18.2 yrs

data S47, 18.2 yrs

THMC, 5.3 yrs

THMC, 18.2 yrs

0.E+00

1.E-01

2.E-01

3.E-01

4.E-01

5.E-01

6.E-01

7.E-01

0.4 0.6 0.8 1 1.2 1.4

Co

nce

ntr

atio

n (

mo

l/L)

Radial distance (m)

Na+

data S29,S19,5.3 yrs

Sq data, S47, 18.2 yrs

data, S47, 18.2 yrs

THMC, 18.2 yrs

THMC, 5.3 yrs

Side view approx. 40m

6

Full-scale heater test undertaken as ultimate test for performance of geological

disposal in Opalinus Clay

Focus is on understanding THM behavior of near-field

host rock and engineered barrier system components

Objectives are to confirm integrated disposal system

behavior, validate coupled THM models used for PA,

and demonstrate buffer emplacement technology

DOE is one of seven organizations participating in the

design, analysis, and interpretation of the test

FE Heater Test at Mont Terri

Shotcrete Steel archesHeaters on bentonite

blocks

«Interjacent sealing section»

without shotcreteFE gallery

3m Ø, 50m length

FE cavern

Plug

DOE Activities Associated with FE

Heater Test at Mont Terri

THM model features:

Thermally driven THM evolution in both the

EBS components and the host-rock behavior in

argillaceous formations

Re-saturation and swelling of the protective

buffer around the waste package

Supporting GDSA

Validation of coupled THM model of bentonite

and clay host rocks

Supply GDSA with flow properties (e.g.

porosity and permeability) evolution in the buffer,

excavation disturbed zone and host rock

Inform GDSA related to local flow created by

coupled THM processes

Integration to GDSA

Abstraction and direction incorporation

Validating PA model for clay repository

DECOVALEX Project(DEvelopment of COupled models and their

VALidation against EXperiments)

DECOVALEX was established in 1992, and has been active since, in several project stages

– The objective is to achieve a better understanding and improved modeling of the effects of coupled

(T-H-M-C) processes in nuclear waste repositories

– Past DECOVALEX activities have included several international programs and research tasks with focus on

clay and granite repositories

– DOE formally joined DECOVALEX-2015 project phase in Spring 2012

– New DECOVALEX-2019 Phase just started in Spring 2016

DECOVALEX-2015 participations provided

access to several sets of experimental data

from different URLs and different host

rocks

− Sealing experiment at Tournemire URL (clay)

− Heater tests at Mont Terri URL and Horonobe

URL (clay)

− Bedrichov Tunnel Experiment on fracture flow

and transport patterns (crystalline)

DECOVALEX-2019 provides new tasks

tackling a variety of relevant R&D issues

8

EBS Experiment at

Horonobe URL

New DECOVALEX-2019 Tasks

Core Tasks: Task A: ENGINEER – Modeling advective gas flow through low permeability

materials.

Task B: Fault Slip Test - Modelling the induced slip of a fault in argillaceous rock.

Task C: GREET – Hydro-mechanical-chemical-biological processes during groundwater recovery.

Task D: INBEB – Hydro-mechanical interactions in bentonite engineered barriers.

Task E: Upscaling Heater Tests – Upscaling of modelling and experimental results from small scale to one-to-one scale.

Supporting Tasks: Task F: FINITO - Fluid inclusion and movement in tight rock.

Task G: EDZ Evolution - Reliability, feasibility and significance of Measurements of conductivity and transmissivity of the rock mass for the understanding of the evolution of a repository of spent nuclear fuel

DOE Activities Associated with

DECOVALEX-2019: ENGINEER (BGS)

Lab tests by BGS

Task A of DECOVALEX-2019 project will provide extensive experimental and field test

results on the behavior of gas generation and pressurization in bentonite and clay stone,

including dilation and fracture formation.

Relevance to GDSA:

Pressure buildup and

gas migration in

bentonite and clay stone

Understand processes

Upgrade process model

Feed into GDSA

SKB Task Forces

SKB has two task forces for Groundwater Flow and Transport of Solutes (GWFTS, since 1992) and Engineered Barrier Systems (EBS, since 2004)

These task forces are a forum for international organizations to interact in the area of conceptual and numerical modeling of performance-relevant processes

Different modeling tasks, often involving experiments carried out at the Äspö HRL in Sweden, are addressed collaboratively

GWFTS Task Force: To develop and apply appropriate methods for flow and transport in fractured crystalline rock

EBS Task Force: To develop and apply tools for the advanced coupled THMC analysis of buffer/backfill materials

11

Äspö HRL

Prototype Repository

LTDE

GWFTS Task 9B: Long-term Transport

Relevance to GDSA

Generation and representation of realistic fracture networks

Fluid flow & transport in fracture networks

Mapping tools (dfnWorks to PFLOTRAN)

Dual continuum; matrix diffusion

HotBENT - Studying the effects of high

temperatures on clay buffers/near field

13

A planned collaboration project, led by

NAGRA, to conduct a joint GTS

experiment integrated with lab and

modeling studies to evaluate buffer

behavior at 150 oC to 200 oC

DOE Activities Associated with

HotBENT

Scoping calculation based on

THMC model for FEBEX-DP

0

10

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40

50

60

70

80

0 1000 2000 3000 4000 5000 6000 7000 8000R

elat

ive

hu

mid

ity

(%)

Time (day)

R = 0.52 m

WCSE2-03 WCSE2-04

WCSE1-03 WCSE1-04

FEBEX, 100 °C HotBENT 200 °C

Bentonite near the heater remains

fairly dry for a long time whereas

bentonite near the granite because

fully saturated rapidly just like that in

FEBEX test.

THMC model features:

Thermally driven THMC evolution in both

the EBS components and the host-rock

behavior in crystalline formations

Re-saturation and swelling of the

protective buffer around the waste package

Supporting GDSA

Validation of coupled THMC model of

bentonite and crystalline host rocks

Supply GDSA with long term alteration of

bentonite under high temperature.

Integration to GDSA

Abstraction and direction incorporation

Validating PA model for crystalline

repository under high temperature

Active collaboration with international programs, initiatives, or

projects is beneficial to DOE’s disposal research program,

providing access to decades of experience gained in various

disposal environments

Focus is on partnerships that allow “active” R&D collaboration in

underground research laboratories

Improved understanding of near-field perturbation, engineered barrier integrity, and RN transport

Testing of advanced process-modeling tools against experimental data at scale

Establishing databases for PA model validation

Collaboration with international partners builds science communities and provides opportunities for learning

15

Summary and Conclusions