1. 13 th Exchange Meeting The role of cementitious materials for deep disposal of high-level waste in Boom Clay Use of cementitious materials in the PRACLAY experimental programme Wim Bastiaens ESV EURIDICE GIE Mol, 29 January 2009

2. 13 th Exchange Meeting 29 January, 2009 WBa/2 Introduction  PRACLAY: PReliminAry demonstration test for CLAY disposal of highly radioactive waste  Aim: to demonstrate the feasibility of the reference design for deep disposal of HLW

3. 13 th Exchange Meeting 29 January, 2009 WBa/3 The PRACLAY project PRACLAY In SituPRACLAY Surface (Generic) (Design specific) Demonstration experiments Repository construction feasibility Demonstration Experiments Construction, handling and performance of EBS (Engineered Barrier Systems) Examples: Ophelie mock-up, supercontainer construction, backfill test ESDRED (EC) Confirmation experiments The PRACLAY Heater Test Supporting studies (T-H-M) Atlas, CLIPEX (EC), SELFRAC (EC),TIMODAZ (EC), …

4. 13 th Exchange Meeting 29 January, 2009 WBa/4 The PRACLAY project PRACLAY In SituPRACLAY Surface (Generic) (Design specific) Demonstration experiments Repository construction feasibility Demonstration Experiments Construction, handling and performance of EBS (Engineered Barrier Systems) Examples: Ophelie mock-up, supercontainer construction, backfill test ESDRED (EC) Confirmation experiments The PRACLAY Heater Test Supporting studies (T-H-M) Atlas, CLIPEX (EC), SELFRAC (EC),TIMODAZ (EC), … Ophelie Day 10/06/2004 www.euridice.be Presentations by Bart Craeye & Lou Areias

5. 13 th Exchange Meeting 29 January, 2009 WBa/5 Section to be backfilled ~30 m long ~90 m³ of material PRACLAY surface: ESDRED (EC)

6. 13 th Exchange Meeting 29 January, 2009 WBa/6  Prevent collapse of the gallery lining (and potential damage of the supercontainer)  Prevent/limit creep of Boom Clay (with potential destabilization of the surrounding host formation)  Main requirement is a high filling ratio  There are some constraints on the materials The backfill material has two main roles/functions

7. 13 th Exchange Meeting 29 January, 2009 WBa/7 Two backfilling techniques tested in the scope of ESDRED  Backfilling by pumping a grout  Backfilling by projecting a granular material

8. 13 th Exchange Meeting 29 January, 2009 WBa/8 Programme objectives: ‘grout technique’  Development of a grout with specific requirements (related to operational and LT safety aspects): High pH (corrosion protection) Sufficiently high thermal conductivity (> 1 W/mK) Compressive strength between 3 and 10 MPa (retrievability) Limited quantity of chemical additives (RN complexes) and no sulfur containing species (corrosion) Hardening time < 4 days (operation) Fluidity sufficient to fill a 30 m long section

9. 13 th Exchange Meeting 29 January, 2009 WBa/9 Programme objectives: ‘grout technique’  Verify preparation aspect (logistics) at large scale  Verify emplacement aspect at large scale  Verify that grout properties (emplacement and behaviour) are maintained under thermal load  Reduced scale test: 2/3, Ø2.5m  Full scale test: Ø3.5m

10. 13 th Exchange Meeting 29 January, 2009 WBa/10 Grout composition  Binding medium Portland cement (CEM I)  High compressive strength (52.5 N)  High Sulphate Resisting (HSR)  Low Alkali level (LA) Limestone powder  Additive Superplasticizer Glenium®  Sand Calibrated river sand 0 - 4 mm, washed and dried

11. 13 th Exchange Meeting 29 January, 2009 WBa/11 Design of the reduced-scale mock-up

12. 13 th Exchange Meeting 29 January, 2009 WBa/12 Reduced-scale test (June 2006)  Flow rate ~ 3 m³/h  Hardening < 4 days  No segregation observed  Hardened material homogeneous  Rheological properties of grout were suitable  100 % filling ratio obtained  Main injection tube was sufficient  Design of main injection tube was suitable  Properties of hardened material Density = 2200 kg/m³ λ = 1.6 W/mK (fully dried) k = 10-12 m/s (water). Grout composition was found to be suitable for full-scale test

13. 13 th Exchange Meeting 29 January, 2009 WBa/13 Construction and design of the full-scale mock-up

14. Main injection (at 25m depth) Back-up injection Vent

15. 13 th Exchange Meeting 29 January, 2009 WBa/15 Full-scale test: grout preparation and tests (April 2008)  2 cranes  3 trucks (10 m³)  1 pump + reserve  240 big bags (1T, pre-mix)  88 m³ grout  On-site tests

16. 13 th Exchange Meeting 29 January, 2009 WBa/16 Grout injection  Temperature: ~65°C  Time needed: +/- 7 hours  Average flow rate: 15.1 m³/h (11.7  24 m³/h)  Pump breakdown (replacing it took ~1h)  Main injection tube is sufficient Back-up was used after pump breakdown  About 2-3 m³ of water/grout was ejected through the vent

17. 13 th Exchange Meeting 29 January, 2009 WBa/17 Grout injection  4 days after the test ~99 % filled Small gap at the top (filled with water)  About 900 l was removed (1.1 % of total volume)  Gap dimensions from 0.5 cm (end cover) to 5 cm (front cover) 5 cm 0.5 cm

18. 13 th Exchange Meeting 29 January, 2009 WBa/18 Grout behaviour  The grout hardened partially and very slowly (  small scale test)  NOT caused by Difference of compositions (chemical analyses) Problem with cement quality (chemical analyses) Segregation during pumping (not likely according to Magnel, CSTC, Glaser)  Different boundary conditions  W/C ratio during full scale test at the high end of the functioning range Reduced scale testFull scale test Temperature 45°C65°C Diameter 2.5 m3.5 m Reinforcement of the setup Bars (  not impervious)Metal sheet (  impervious)

19. 13 th Exchange Meeting 29 January, 2009 WBa/19 Lessons learnt from backfill tests  Material development based on industrial knowledge; properties +/- OK  Backfilling 30 m: yes we can!  The design of the mock-up and internal components was OK (cf. injection tubes)  Logistic aspects are important  The saturation and design of the concrete lining of the disposal galleries could have an influence Further need to tailor the grout: larger functioning zone Continuing theoretical/design studies (for SFC-1) to translate knowhow from tests to repository configuration

20. 13 th Exchange Meeting 29 January, 2009 WBa/20 The PRACLAY project PRACLAY In SituPRACLAY Surface (Generic) (Design specific) Demonstration experiments Repository construction feasibility Demonstration Experiments Construction, handling and performance of EBS (Engineered Barrier Systems) Examples: Ophelie mock-up, supercontainer construction, backfill test ESDRED (EC) Confirmation experiments The PRACLAY Heater Test Supporting studies (T-H-M) Atlas, CLIPEX (EC), SELFRAC (EC),TIMODAZ (EC), …

21. 13 th Exchange Meeting 29 January, 2009 WBa/21 Construction history  Phase 1 1980 - ’87pioneering + R&D  Phase 2 1997 - ’07demonstration

23. 13 th Exchange Meeting 29 January, 2009 WBa/23 Construction feasibility  Use of cementitious materials in HADES mainly linked to the lining First shaft  Poured concrete

24. 13 th Exchange Meeting 29 January, 2009 WBa/24 Construction feasibility  Use of cementitious materials in HADES mainly linked to the lining Experimental works / Test Drift  Unreinforced concrete segments  Wooden interlayers to limit ground pressure  Installed manually

25. 13 th Exchange Meeting 29 January, 2009 WBa/25 Construction feasibility  Use of cementitious materials in HADES mainly linked to the lining Second shaft Prefab segments + shotcrete + cast concrete

26. 13 th Exchange Meeting 29 January, 2009 WBa/26 Construction feasibility  Use of cementitious materials in HADES mainly linked to the lining Connecting gallery / PRACLAY gallery  Unreinforced concrete segments  Wedge block technique  Installed with erector

27. 13 th Exchange Meeting 29 January, 2009 WBa/27 Construction feasibility  Evolution of the properties of the lining Higher strength Lower thickness Manual  mechanised installation Lower host rock disturbance  Limit overexcavation  Avoid additional convergence after lining installation

28. 13 th Exchange Meeting 29 January, 2009 WBa/28 Construction feasibility  Monitoring of strains in lining (CG) Correction for creep phenomena is important  External ground pressures Test Drift: 1.6 – 2.4 MPa (De Bruyn et al. 1995) Connecting Gallery: 2.1 – 3.1 MPa (Ramaeckers & Van Cotthem 2003)

29. 13 th Exchange Meeting 29 January, 2009 WBa/29 The PRACLAY project PRACLAY In SituPRACLAY Surface (Generic) (Design specific) Demonstration experiments Repository construction feasibility Demonstration Experiments Construction, handling and performance of EBS (Engineered Barrier Systems) Examples: Ophelie mock-up, supercontainer construction, backfill test ESDRED (EC) Confirmation experiments The PRACLAY Heater Test Supporting studies (T-H-M) Atlas, CLIPEX (EC), SELFRAC (EC),TIMODAZ (EC), …

30. 13 th Exchange Meeting 29 January, 2009 WBa/30 The PRACLAY heater test  Demonstrate that thermal loading doesn’t compromise the role of Boom Clay in the disposal system  Combination of excavation (EDZ) and thermal loading  Study the interaction between the host rock and the lining (cf. retrievability)  Verify current knowledge of THM(C) processes  Large scaleheated section ~35m (~80°C)  Long termheat during 10 years

31. 13 th Exchange Meeting 29 January, 2009 WBa/31 The PRACLAY heater test  Some tailor-made concrete applications  Lining C80/95 (“normal” wedge blocks) Very high-strength concrete (Ceracem®, Eiffage)  End plug Compressive concrete (Solexperts) Grout

32. 13 th Exchange Meeting 29 January, 2009 WBa/32 PRACLAY heater test: lining  Geotechnical load case Host rock2.5 MPa Anisotropy1.1 (1.4)  Thermal load Temperature increase ~70°C Temperature gradient ~10°C  Conservative calculation (no possibility for dilation) leads to stresses in the lining up to 110 MPa during the thermal phase

33. 13 th Exchange Meeting 29 January, 2009 WBa/33 PRACLAY heater test: lining  C80/95 unreinforced concrete  Expansions joints to allow thermal dilation Stainless steel foam panels, silicone rubber sheets

34. 13 th Exchange Meeting 29 January, 2009 WBa/34 PRACLAY heater test: lining  Stainless steel foam panels Elasto-plastic behaviour  Small compression before thermal phase  Start to compress before the concrete fails (allow thermal dilation) Compression tests have confirmed the elasto-plastic behaviour  Test necessity of joints: rings without Special concrete: > 125MPa on cylinder Fibre reinforced concrete (Ceracem®)

35. 13 th Exchange Meeting 29 January, 2009 WBa/35 PRACLAY heater test: end plug

36. 13 th Exchange Meeting 29 January, 2009 WBa/36

37. 13 th Exchange Meeting 29 January, 2009 WBa/37

38. 13 th Exchange Meeting 29 January, 2009 WBa/38 Conclusions  EIG EURIDICE uses cementitious materials in on surface and in-situ tests  Backfill experiments (ESDRED) Demonstrate the feasibility of grouting technique Give important input for future design  Cementitious materials are important construction materials for a disposal site / URF  Concrete (lining) technology has evolved over time  Some tailor made concrete solutions were necessary to cope with the specific experimental conditions of the PRACLAY heater test