91 92. june 9 overview febex-dp-and_ufd r&d activities related to febex-dp_zheng

1. Used Fuel Disposition Campaign
FEBEX-DP Collaboration
Liange Zheng, Hao Xu, Jonny Rutqvist, Jens Birkholzer
Lawrence Berkeley National Laboratory
June 9, 2016

2. Used
Fuel
Disposition
Part 1: Overview of FEBEX-DP
 FEBEX: Full-scale Engineering Barriers EXperiment
 Experiment were based on Spanish HLW
emplacement concept for a granitic host rock
 It was initiated by ENRESA in 1994 under the
auspices of EU
 It is composed of laboratory experiments, Mock-up
and in situ tests, and THC/THM modeling.
Mock-up test
February 1997– now
Galleries

3. Used
Fuel
Disposition
FEBEX
Jan 1996 – Jun 1999
FEBEX II
Aug 2000 – Dec 2004
NF-PRO (WP3.3)
Jan 2005 – Dec 2007
FEBEX-e
Planning
and design Set-up 1st Operational Phase 2nd Operational Phase Excavation
94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
FEBEX-DP
16
Partial dismantling Final dismantling
FEBEX in situ Test
Zürich
Grimsel

4. Used
Fuel
Disposition
FEBEX: in situ Test
Partial Dismantling of heater 1 (2002)
Dismantled section

5. Used
Fuel
Disposition
FEBEX–DP: Dismantling of heater 2
Objectives
 Bentonite characterization
– Density, water content and spatial distribution
– Chemical changes
 Characterization of corrosion and
microbial processes
– On instruments/sensors and coupons
– Bacterial growth
– All under evolving redox-conditions
 Mineralogical interactions at material
interfaces
– Concrete - bentonite, heater/liner – bentonite,
rock - bentonite
– Impact on pore water composition
 Integration of the monitoring results and
modelling
– THM/THMC modelling
– Pre- and post dismantling
5

6. Used
Fuel
Disposition
S49
FEBEX–DP: Dismantling of heater 2

7. Used
Fuel
Disposition
Hot
sections
Cold
sections
Hot
sections
Cold
sections
FEBEX–DP: Dismantling of heater 2

8. Used
Fuel
Disposition
Part 2: UFD R&D Activities Related to
FEBEX-DP
Coupled THMC modeling
The hydration of bentonite:
Non-Darcy flow – the presence of a threshold gradient
Decrease of intrinsic permeability of the buffer due to swelling
Action of thermal osmosis to counteract flow towards the heater
The chemical evolution in the bentonite
Changes of more soluble minerals (gypsum, calcite and pyrite) and aqueous
concentration, evolution of pH and Eh, alteration of smectite
Experimental work
 Synchrotron X-ray Microtomography Measurements to characterize the micro-
cracks of the bentonite(LBNL).
 Characterization of the microstructure of Bentonite and interface areas using
SEM – EDS – BSEI and X-ray CT Scan (SNL)
 Hydrothermal Experiments (LANL)

9. Used
Fuel
Disposition
THMC Modeling: Key Model
Features
1D Model For hot sections
Chemical reactions includes aqueous complexes, cation
exchange, mineral dissolution-precipitation
 Two mechanical models were tested
Linear Swelling:
dSlKd sws βσ 3=
Porosity change:
Permeability change:
( )K
ekk
0
0
σσ −
=
BExM

10. Used
Fuel
Disposition
0
5
10
15
20
25
30
35
0.4 0.6 0.8 1 1.2
Watercontent(%)
Radial distance (m)
Data 5.2 yrs Data 18.3 yrs
THMC-LS, 5.2 yrs THMC-LS, 18.3 yrs
THMC-BExM5.2 years THMC-BExM18.3 yrs
Model Results: T, RH and WC
Observations: As expected, THMC model
outperform TH model in matching the RH data
near the heater.
THMC model reasonably match the water
content and porosity data at 5.2 years
(dismantling of heater 1) and at 18.3 years
(dismantling of heater 2).
The cooling period after heaters were switched
off leads to significant redistribution of
moisture.
0
10
20
30
40
50
60
70
80
90
100
0 1000 2000 3000 4000 5000 6000 7000
Relativehumidity(%)
Time (day)
R = 0.52 mWCSE2-03
WCSE2-04
WCSE1-03
WCSE1-04
THMC-LS
TH model
THMC-BExM
Temperature
Relative humidity
Water
content

11. Used
Fuel
Disposition
Model Results: Stress
E2F2
Observations:
Reasonable match between model results
and stress data.
-1
0
1
2
3
4
5
6
7
8
9
0 1000 2000 3000 4000 5000 6000 7000
NormalStress(MPa)
Time (day)
E2data, r=1.1 m
F2 data, r=1.1m
THMC-LSRadial
THMC-LScircumferential
THMC-BExMradial
THMC-BExMcircumferential -1
0
1
2
3
4
5
6
7
8
9
0 1000 2000 3000 4000 5000 6000 7000
NormalStress(MPa)
Time (day)
E2data, r=0.5 m
THMC-LScircumferential
THMC-LSRadial
THMC-BExMcircumferential
THMC-BExMradial

12. Used
Fuel
Disposition
Model Results: Cl-
Observations:
Porosity increase and permeability reduction in THMC model does not significantly improve
the fit to measured Cl data;
However, after 18 years, the model results for the THC and THMC model are similar.
Increase in permeability near the granite improves the fit to Cl data
0.E+00
5.E-02
1.E-01
2.E-01
2.E-01
3.E-01
3.E-01
4.E-01
0.4 0.6 0.8 1 1.2 1.4
Concentration(mol/L)
Radial distance (m)
Cl- data S29, 1930 days
data S19, 1930 days
data S28, 1930 days
THC model, 5.2 yrs
THC model, 18.3 yrs
THMC-LS5.2 yrs
THMC-LS, 18.3 yrs
THMC-BExM, 5.2 yrs
0.E+00
5.E-02
1.E-01
2.E-01
2.E-01
3.E-01
3.E-01
4.E-01
4.E-01
0.4 0.6 0.8 1 1.2 1.4
Concentration(mol/L)
Radial distance (m)
Cl-
data S29, 1930 days
data S19, 1930 days
data S28, 1930 days
THMC-LSbase
THMC-LSsensitivity
( )0
0
φ
φ
A
ekk =A Sensitivity case

13. Used
Fuel
Disposition
Checking the Microscopic Structure
Synchrotron X-ray Microtomography Measurements
- Characterization of the microstructure of the material.
- Description of the crack network in a quantitative fashion.
- Study the mechanisms involved in the propagation of cracks.
- Provide data for models.
Scanned with the 3.22 μm resolution setup
S59

14. Used
Fuel
Disposition
Sample as is (cropped), FOV ~6mm, 3.22 μm vx sizeVirtual cut to show the inside of the sampleCut sample with the medial axis of the crack network labeled with the aperture valueAll the (aperture color labeled) medial axes of the cracks in the sampleConnected component labeling of the fractures larger than 1000 vx in volume
Checking the Microscopic Structure

15. Used
Fuel
Disposition
B-D-59-15B-D-59-8B-D-59-3
Sample rendering Aperture-labeled medial axes Overlapped data
1 mm
Checking the Microscopic Structure

16. Used
Fuel
Disposition
Bentonite – Concrete Interface
Characterization (SEM – EDS –
BSEI) (SNL)
16
Back-Scattered Electron Image (BSEI) of
Bentonite – Cement Interface
X-ray Map Line Scan: Ca
Portlandite Grain?
Approx. Interface
Location
 So far – no indication of strong
elemental gradients beyond the
interface region
 Cracks (desiccation?) tend to be
abundant at the interface
 Portlandite mineralization at the
interface?
 More elemental line-scans needed to
resolve compositional gradients
Work in Progress!!!

17. Used
Fuel
Disposition
Ongoing and Future Work
Coupled THMC modeling
Considering thermal osmosis and dual continuum for
transport to improve the fit to conservative species.
Refining chemical models to match reactive species
Synchrotron X-ray Microtomography
Measurements
Taking more measurements for samples for section 59 and
49
Developing a tool to characterize the fracture network in a
quantitative fashion

18. Used
Fuel
Disposition Sample from B-D-59-8
Thin horizontal slice from the whole measured volume, highlighting the microstructure and
the fracture network (in yellow, on the right).
1 mm

19. Used
Fuel
Disposition Sample from B-D-59-15
Thin horizontal slice from the whole measured volume, highlighting the microstructure and
the fracture network (in yellow, on the right).
An aggregate particle in this sample displays negative crystals (dissolution?)
1 mm

20. Used
Fuel
Disposition
Displaying a thin slice of the sample reveals some more details about the method:
B-D-59-3 B-D-59-8 B-D-59-15
To quantify the fracture network characteristics of the different samples we use a simple
procedure (optimization of the process is ongoing):
- Segment the voids from the dataset
- Calculate the medial axis of the resulting binary dataset
- Calculate the local thickness of the binary dataset
- Label the medial axes with the local thickness value in the same position
A statistical analysis of the aperture values becomes now possible and can be used to
characterize and compare different sample in a quantitative fashion.
.5 mm

21. Used
Fuel
Disposition
Example of the results from a 3.22mm x 3.22mm x 1.61mm volume for each
sample (3.22 μm voxel size, theoretical resolution)
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
500000
5 15 25 35 45
0
5
10
15
20
25
30
35
5 15 25 35 45
BD 59-3
BD 59-8
BD 59-15
Bin [μm] Bin [μm]
Aperture analysis of the medial axes:
Absolute values %
Larger amount of small
voids due to a very
(micro-) porous
aggregate particle in BD
59-15
BD 59-3 has
larger fractures
The negative
crystals of BD 59-15
contribute to the
larger aperture
values amount

22. Used
Fuel
Disposition Some comments/conclusions
- Synchrotron X-ray microCT can be used effectively to characterize the microstructure
of the sample, with special focus on fracture networks.
- Measurements at different resolutions found that a 3.22 μm vx size and ~6 mm field of
view is the best compromise, in the context of the resolution vs. FOV problem.
- Still, given the high heterogeneity of the samples, the volumes investigated are hardly
representative of the whole material. Plus sampling issues can be present as well.
- Encouraging results have been obtained in the perspective of developing an
experimental strategy to monitor the development of cracks during the sample drying,
to obtain further information about the fracturing mechanisms present.
- Quantitative characterization of the voids/fractures in the sample can be successfully
carried out to compare different volumes and/or samples.