Experimental program in the URL

Transcription

1 Experimental program in the URL Jacques Delay Deputy Scientific Director July th 2009 AGENCE NATIONALE POUR LA GESTION DES DÉCHETS RADIOACTIFS

2 URL First construction step ( ) Experimental drift Main shaft Auxiliary shaft Experimental drift 445 m 490 m Technical drift Technical drifts 490 m

3 Stations at 490 m 3 AGENCE NATIONALE POUR LA GESTION DES DÉCHETS RADIOACTIFS

4 Experimental Drifts KEY and GEX 4

5 Experimental Program Convergence measurements: Rock mass behavior around excavations -- behavior of drifts and shafts Main shaft survey Drift survey Physical properties of the argillaceous rocks Permeability and pore pressure Porewater chemical and isotopic composition Diffusion and retention Thermal properties EDZ Interruption through radial slots in a sealing zone 5

6 Rock mass behavior during and after shaft excavation 6

7 Rock mass behavior during and after drifts excavation 7

8 Rock mass behavior during and after drifts excavation C o n v e r g e n c e ( m m ) vert. conv. σh 140 horiz. conv. σh vert. conv. σh horiz. conv. σh Time (j) At -445 m, overall behavior is elastic and damage is limited At -490 m, complex mechanical behavior. Chevron-shaped shear fractures observed at the drift walls and through drilling Initial deformations compatible with the Elasto-Plastic model (EP) up to 1 diameter After 1 diameter viscoplasticity is important Strong hydromechanical coupling Influence of the natural stresses

9 Permeability and pressure measurements 380 All boreholes Boreholes from the drifts D e p t h ( m ) K c o x s it e + la b o. g r f m/s m/s E E E E E E Permeability (m/s) Permeability (m/s) In situ permeability: to m/s, identical to ranges observed on samples Overpressure in argillaceous rocks with respect to the encasing units up to 60 meters of water Observed coupled osmotic effects tested in the URL 9

10 Chemical and isotopic characterization of pore water 10

11 Chemical pore water characterization 1.0E E-02 mol/l Eq / L 1.0E-03 Seepage water 430 m Seepage water 475 m Seepage water 490 m Seepage water 504 m Predictive model 1.0E-04 Sr K Mg Ca Na Cl SO4 TIC Compositions in the domain predicted by the model In situ water sampling helps improving the model 11

12 Diffusion and retention properties 12

13 Diffusion and retention properties Cl EST208 In situ verification of the expected behaviors: Effect of anionic exclusion Effect of chemical retention Cl Typical behavior of tracers assessed in situ for the I/S R0 and R1 mineralogies C /C Cs HTO HTO Hydrodynamic and modeling tests highlight the presence of an approximately 2.5-cm-thick disturbed wall zone Time (d) Temps (j) 13 Modeling taking into account this disturbed wall zone helps assess the diffusion parameters in the undisturbed rock, in good agreement with those obtained on samples

14 Thermal and thermo-hydromechanical properties 14

15 Temperature [ºC] Heater 0.6 m Rock sensor TER1203_TEM3 1203_TEM _sim03 Thermal and thermo- hydromechanical properties Thermal parameters (λ, Cp) and THM (permeability, thermal expansion ratio) analyzed and compared with values measured on samples Time [days from start of heating] 1401_P _sim_01 Thermal conductivity (λ// = 2 W.m -1.K -1 and λ = 1,3 W.m -1.K -1 ; Cp = 1005 W.kg -1. K -1 ) identical to values on samples Overpressure [MPa] The thermal expansion ratio fitted on tests (in the order of C -1 ) corresponds to the values measured on samples in the bedding plane Time [days from heating] 15 Fitted permeability is within the standard range

16 Interruption of the damaged zone in a sealing plug 16 Relevence test of the concept of interruption of circulations along a drift Assessment of the rock mass behavior around the slot during saturation and comparison with that observed during pressure tests (flat jacks) Assessment of the engineering and monitoring of the pressure induced by swelling of the clay at full saturation

17 Scientific contribution of the Laboratory end Underground Experiment Confining ability of the argillaceous rocks In situ confirmation of the rock-confining properties (permeability, pore water geochemistry, diffusion and retention parameters) and representativeness of the parameters acquired on samples Confirmation of the argillaceous rocks behavior and the absence of fractures on the laboratory site through detailed reconstitution of the geological history eformations of the rock mass and feasibility of shafts, drifts and vaults Feasibility to build and support disposal elements Strong hydro-mechanical coupling within the argillaceous rocks alidity of the concepts retained for the disposal facility Preliminary thermal conductivity results confirm the data used to assess the design of Dossier 2005 Preliminary demonstration on the feasibility to seal drifts (slot drilled in argillaceous rocks, filled with bentonite) 17

18 The New Context for the deep disposal facility : next steps Andra as taken over the responsibility of the use and maintenance of the underground installation since July New excavation works are in progress. Main topics of the new program: Select a disposal site Acquire new scientific data for the design of the disposal facility (thermal and hydro-mechanical behavior) and for the safety assessment (migration properties and large scale clay properties variability). Design and run technical processes for drifts and vaults, building and closure. Carry out real-scale experiments in view of supporting the technical feasibility of a deep disposal facility. 18

19 Transposition Zone Within the transposition zone for underground repository (250 km 2 ) step 2009: selection of a 30 km 2 zone for the location of the future underground disposal facility and for specific scientific surveys 19

20 Select a Deep Disposal site Over the period, a geological survey was carried out on the transposition zone defined around the the Meuse/Haute-Marne URL (250 km²) Andra will propose in autumn 2009 a restricted zone of interest (about 30 km²) for the continuation of research. Over the period, a detailed survey (3D geophysics) will be carried out on the restricted zone of interest. Within the framework of the public discussion scheduled in the law, Andra will propose one or several proposals for the siting of the future repository. The site chosen in 2013 constitutes a major input for the DAC to be presented at the end of 2014.

21 Survey of the Transposition Zone (step: ) Seismic 2D survey (165 km) Drilling Campaign Complementary geological surveys And reprocessing of 140 km of previous seismic profiles. 21

22 URL Experiments: 1st phase (1) Technology 1. Drifts Improving and comparing methods of excavation (road header) and of support (bolts) comparison of long-term mechanical evolution of structures between flexible and stiff durable lining (duration of exploitation and reversibility) Hydraulic and mechanical follow-up 2. C waste cells Improving excavation technology vs casing concept on short microtunnel (casing/rock gap, EDZ, length limit) Building a cell plug, using a roadheader

23 EDZ URL Experiments: 1st phase (2) Improved understanding of basic phenomena and coupling between phenomena and at interfaces between repository components network evolution due to the coupling between mechanical behaviour and degree of saturation (drift and C cell test follow up, experiments in boreholes) permeability evolution vs resaturation and stress state Gas transfers and hydric conditions tests in boreholes (gas permeability of argillites, gas entry pressure, microcracking threshold). Resaturation kinetics Thermal behaviour new experiment (better environmental conditions, test plan more representative of a disposal context)

24 URL Experiments: 1st phase (3) Validity of data at different scales Digging downward and upward drifts to survey inframetric vertical variability of argillites (mineralogy, mechanical properties) and to measure its influence on support deformation and EDZ (transposition of URL data to a disposal area) Extrapolation of behaviour laws over the short and medium terms (chemical kinetics, geomechanical) Chemical behaviour of material Tests of concrete and steel samples in boreholes and impact of thermics, Observation of drift lining Test of oxygen consumption by argillite in sealed chamber DIR Long-term radionuclide diffusion and retention in the Callovo-Oxfordian formation

25 URL Experiments: 2nd phase Demonstrators of disposal cells for C waste Construction of a cell at scale 1, using technologies perfected before Construction of several 20m long cells in order to: Follow up of the hydromechanical evolution within the argillite Evaluate the thermal behaviour: emplacement of heater probes simulating exothermic waste packages (effects on temperature, deformation and pore pressure) Test the performance of a cell plug Φ = 0.7 m length = 40 m or more Comparison between different types of drift lining Building of two different drifts Follow-up of induced deformations

26 HL-LL vault test - visual inspection April

27 Planned excavation activities (step: ) Main shaft Auxiliary shaft Experimental drifts HL vaults Level - 445m Level - 490m Experimental drift 27

28 Excavation processes assessment (step: ) Drift GAN Drift excavation work 28

29 Excavation processes assessment (step: ) Drift GT5 Invert construction Drift GT8 - Bolting 29

30 Scientific drilling (step: ) Drift GLS - Borehole OHZ

31 Experimental Drift Design (step: ) 31 AGENCE NATIONALE POUR LA GESTION DES DÉCHETS RADIOACTIFS March, 24 & 25th 2009

32 Drift GED SDZ Experimental Zone SDZ Zone water-tight liner Experimental Drift GED 32

33 Saturation and dewatering Experiment :SDZ Experiment 33

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