Desiccation cracks formation in clay-barrier for nuclear waste disposal

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Desiccation cracks formation in

clay-barrier for nuclear waste disposal

𝑇𝑢𝑒𝑠𝑑𝑎𝑦 16𝑡ℎ 𝑜𝑓 𝐹𝑒𝑏𝑟𝑢𝑎𝑟𝑦 Thesis director : Frédéric Collin

J. Hubert

1

_{– N. Prime}

3

_{– E. Plougonven}

2

_{– A. Leonard}

2

_{– F. Collin}

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1_{Université de Liège – Dep.t ArGEnCo} 2 _{Université de Liège – Dept. Chimie appliquée}

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S

UMMARY OF THE PRESENTATION



Nuclear waste disposal



Material and method



Drying kinetics



Shrinkage



Conclusions

Julien Hubert SUMMARY 16/02/2016

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High activity long life radioactive wastes need to be isolated for a long

period of time ⇒ Deep geological disposal

 Stable and low permeability rock formation required ⇒ in Belgium the studied formation is Boom Clay

Julien Hubert NUCLEAR WASTE DISPOSAL 16/02/2016

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UCLEAR WASTE DISPOSAL

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High activity long life radioactive wastes need to be isolated for a long

period of time ⇒ Deep geological disposal

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N

UCLEAR WASTE DISPOSAL

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

High activity long life radioactive wastes need to be isolated for a long

period of time ⇒ Deep geological disposal

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N

UCLEAR WASTE DISPOSAL

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Deep geological storage

 Burial shaft and multi barrier principle:

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UCLEAR WASTE DISPOSAL

Andra 2005

Boom Clay

Gallery retaining wall Stainless steel liner Buffer Overpack Mechanical support To be filled with a granular material Craye et al., 2009

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S

UMMARY OF THE PRESENTATION

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Nuclear waste disposal



Material and method



Drying kinetics



Shrinkage

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Samples preparation

Julien Huberta MATERIEL AND METHOD 16/02/2016

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ATERIAL AND METHOD

39 mm

34 mm 13 mm

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

Convective drying test

 Sample weighed every 30 seconds in the convective dryer

Julien Hubert MATERIEL AND METHOD 16/02/2016

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ATERIAL AND METHOD

Drying conditions

Temperature

25°C

Humidity

3,5 %

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

Data acquisition and image processing

 Shrinkage and cracking measurement

Julien Hubert MATERIEL AND METHOD 16/02/2016

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ATERIAL AND METHOD

Skyscan 1172

Hole filling and binarization

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S

UMMARY OF THE PRESENTATION



Nuclear waste disposal



Material and method



Drying kinetics



Shrinkage



Conclusion

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

Theory of porous media drying kinetics

Julien Hubert DRYING KINETICS 16/02/2016

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RYING KINETICS

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Theory of porous media drying kinetics

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D

RYING KINETICS

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Theory of porous media drying kinetics

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D

RYING KINETICS

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Theory of porous media drying kinetics

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RYING KINETICS

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0 5 10 15 20 1.3 1.4 1.5 1.6 1.7 1.8 Time [h] Ma ss [g ] Sample 1 Sample 2 Sample 3 0 0.05 0.1 0.15 0.2 0.25 -2 -1 0 1 2 3 4 5 x 10-4 Moisture content [-] D ryi n g ra te [ kg /(m²s)] Sample 1 Sample 2 Sample 3

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Experimental results

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RYING KINETICS

0 5 10 15 20 -2 -1 0 1 2 3 4 5 x 10-4 Time [h] D ryi n g ra te [ kg /(m²s)] Sample 1 Sample 2 Sample 3

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Porous medium

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RYING KINETICS

Porous medium surface

Liquid Water Air + vapor Solid matrix Liquid water Air + vapor Solid matrix

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Internal water transfer

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RYING KINETICS

Liquid Water Air + vapor Solid matrix Liquid water Air + vapor Solid matrix Darcean flow Vapor diffusion Evaporation

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Limit layer model

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Heat flux : 𝑞_ℎ = 𝐿𝑞_𝑤 − 𝛽(𝑇_𝑎𝑖𝑟 − 𝑇_{𝑠𝑢𝑟𝑓}) Water flux : 𝑞_𝑤 = 𝜶(𝜌_{𝑣,𝑠𝑢𝑟𝑓} − 𝜌_{𝑣,𝑎𝑖𝑟})

D

RYING KINETICS

Liquid Water Air + vapor Solid matrix Liquid water Air + vapor Solid matrix Darcean flow Vapor diffusion Evaporation 𝑇_𝑎𝑖𝑟 𝜌_{𝑣,𝑎𝑖𝑟} 𝜌_{𝑣,𝑠𝑢𝑟𝑓} 𝑇_{𝑠𝑢𝑟𝑓} Limit Layer

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Integration of limit layer model into a FEM framework

:

 Use of a special kind of finite element :

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Boundary conditions

 Water pressure at the environment node : 𝒑_𝒄= −𝝆𝑹𝑻

𝑴 𝒍𝒏(𝑯𝑹)

 Temperature at the environment node : 𝑻 = 𝟐𝟓°𝑪

 Transfer coefficients :

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UMERICAL STUDY OF THE DRYING KINETICS

𝜶 [𝒎/𝒔] 𝜷 [𝑾/𝒎²/𝑲]

0.048 53

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Numerical results:

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UMERICAL STUDY OF THE DRYING KINETICS

0 5 10 15 20 -2 0 2 4 6 8x 10 -4 Time [h] D ryi n g ra te [ kg /(m²s)] Sample 1 Numerical Results 0 0.05 0.1 0.15 0.2 0.25 -2 -1 0 1 2 3 4 5 x 10-4 Moisture content [-] D ryi n g ra te [ kg /(m²s)] Sample 1 Numerical results 0 5 10 15 20 1.35 1.4 1.45 1.5 1.55 1.6 1.65 1.7 1.75 Time [h] Ma ss [g ] Sample 1 Numerical results

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S

UMMARY OF THE PRESENTATION



Nuclear waste disposal



Material and method



Drying kinetics



Shrinkage



Conclusion

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

Experimental results

Julien Hubert DRYING SHRINKAGE 16/02/2016

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RYING SHRINKAGE

0 1 2 3 4 5 100 110 120 130 140 150 Time [h] Su rf a ce [ mm²] Sample 1 Sample 2 Sample 3 1 2 3 4 5 6 7 8 9 10 0 5 10 15 Sample name [-] R e la ti ve sh ri n ka g e [ % ]

Experimental parallel shrinkage Experimental perpendicular shrinkage Mean parallel shrinkage

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Numerical mechanical model

 3D Orthotropic hydro-mechanical model

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UMERICAL STUDY OF THE DRYING SHRINKAGE

MECHANICALPARAMETERS(DIZIER, 2011)

𝐸_∥ 700 [𝑀𝑃𝑎] 𝐸_⊥ 350 [𝑀𝑃𝑎] 𝜈_∥∥ 0.25 [−] 𝜈∥⊥ 0.125 [−] 𝐺∥⊥ 1.4 [𝑀𝑃𝑎] 𝜌𝑠 2670 [𝑘𝑔/𝑚³] 6.72 mm 6.1 mm Bedding planes

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Numerical results

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UMERICAL STUDY OF THE DRYING SHRINKAGE

0 5 10 15 20 100 110 120 130 140 150 Time [h] Su rf a ce [ mm²] Sample 1 Numerical result 1 2 3 4 5 6 7 8 9 10 0 5 10 15 Sample name [-] R e la ti ve sh ri n ka g e [ % ]

Experimental parallel shrinkage Experimental perpendicular shrinkage Mean parallel shrinkage

Mean perpendicular shrinkage Numerical parallel shrinkage Numerical perpendicular shrinkage

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Dessication cracking

Julien Hubert CONCLUSION 16/02/2016

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ONCLUSION

Time 0 1 2 3 4 5 1 2 3 4 5

Fratured percentage of the surface [%]

D e p th o f th e sa mp le (mm) Sat 1h 2h 3h Dry

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Andra (2005a). Dossier 2005 Argile. Synthesis: Evaluation of the feasibility of a geological repository in an argillaceous formation, Meuse/Haute Marne site. Technical report, Paris, France.

Bastiens W., Demarche M., 2003. The extension of the URF HADES: realization and observation. Proceedings of the WN'03 Conference, Tucson, USA.

Craeye B., De Schutter G., Van Humbeeck H., Van Cotthem, 2009. Early age behaviour of concrete

supercontainers for radioactive waste disposal. Nuclear Engineering and Design, 239, 23-35.

Gerard P., Charlier, R, Chambon, R, & Collin, F. 2008. Influence of evaporation and seepage on the convergence of a ventilated cavity. Water resources research, 44(5), W00C02.

Léonard A., Étude du séchage convectif de boues de station d’épuration. Suivi de la texture par microtomographie à rayons X. Thèse de doctorat, Université de Liège, Faculté des Sciences appliquées, 2003.

SCK-CEN. R and D for the geological disposal of medium and high level waste in the Boom clay, 2009. URLence.sckcen.be/en/Projects/Project/RD_waste_disposal/Geological_disposal.

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Thank you !

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Skempton coefficient

Julien Huberta QUESTIONS 16/02/2016

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ATURATION

C

ONTROL

7 7.005 7.01 7.015 7.02 7.025 7.03 x 106 20 25 30 35 40 45 50 55 60 Time (s) S tr e ss va lu e ( M P a ) Skempton P u in

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X-Ray tomography characteristics

 Cross section acquisition using a X-Ray microtomography

Julien Hubert QUESTIONS 16/02/2016

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ATERIALS AND METHODS

Skyscan 1172

Source Voltage = 100 kV Filter = Al 0.5 mm 4x4 binning = 900x666 pixel _radiograms Pixel size = 27.27 µm Exposure time = 510 ms Rotation Step (deg)= 0.65 180° rotation 2 vertically-connected scans Scan duration = 8 minutes

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Numerical filter

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Experimental results

0 2 4 6 8 10 12 14 16 18 20 1.35 1.4 1.45 1.5 1.55 1.6 1.65 1.7 1.75 Time [h] M a ss [ g ] 0 2 4 6 8 10 12 14 16 18 20 -2 -1 0 1 2 3 4 5 x 10-4 Time [h] D ryi n g r a te [ kg /( m ²s) ] Sans Filtre LAG=6 0 0.05 0.1 0.15 0.2 0.25 -2 -1 0 1 2 3 4 5 x 10-4 Moisture content [ ] D ryi n g r a te [ kg /( m ²s) ] Sans Filtre LAG=6

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Samples put into chamber with controlled suction (saline solution)



Water content measured ⇒ saturation degree deduced

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ATER RETENTION CURVE

VANGENUCHTEN FORMULATION 𝑆𝑟𝑒𝑠 0 [-] 𝑆_𝑠𝑎𝑡 1 [-] 𝛼_𝑣𝑔 15 [𝑀𝑃𝑎] 𝑚𝑣𝑔 0.449 [-] 𝑛𝑣𝑔 1.70 [-]

Van Genuchten formulation :

𝑆_𝑟,𝑤 = 𝑆_𝑟𝑒𝑠+ 𝑆_𝑠𝑎𝑡 − 𝑆_𝑟𝑒𝑠 1 +𝑝𝑐 𝛼 𝑛𝑣𝐺 −𝑚𝑣𝐺 0 10 20 30 40 50 60 70 80 90 100 1 10 100 Sa tu ra ti ion d egr ee [% ]

Capillary pressure [MPa]

Experimental results Delage et al., 2011 Fitted using Van Genuchten's model

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Quickly homogeneous on the whole sample

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RYING

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HRINKAGE

85 90 95 100 0 1 2 3 4 5 6

Proportion of the initial surface [%]

D e p th [ mm] Sat 1h 2h 3h 4h Sec

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Parameters used :

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UMERICAL STUDY

PARAMETERS VALUES UNITS

HYDRAULICPARAMETERS 𝑘𝑠𝑎𝑡,⊥ 8.10−12 [m/s] 𝑘𝑠𝑎𝑡,∥ 2.10−12 [m/s] n 0.39 [-] MECHANICALPARAMETERS 𝐸_∥ 700 [𝑀𝑃𝑎] 𝐸_⊥ 350 [𝑀𝑃𝑎] 𝜈∥∥ 0.25 [−] 𝜈∥⊥ 0.125 [−] 𝐺_∥⊥ 1.4 [𝑀𝑃𝑎] 𝜌_𝑠 2670 [𝑘𝑔/𝑚³] THERMALPARAMETERS 𝑐_𝑠 2080 _[ 𝐽 𝑘𝑔 ∗ 𝐾] 𝜌𝑠 2670 [𝑘𝑔/𝑚3] 𝑐𝑤 4185 [ 𝐽 𝑘𝑔 ∗ 𝐾] 𝜌𝑤 1000 [𝑘𝑔/𝑚3] 𝑐𝑎 1004 [ 𝐽 𝑘𝑔 ∗ 𝐾] 𝜌_𝑎 1.2 [𝑘𝑔/𝑚3_]