Kallion In Situ tutkimukset Huokostilan kuvaus 14 C-PMMA menetelmällä

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1 Kallion In Situ tutkimukset Huokostilan kuvaus 14 C-PMMA menetelmällä Maarit Kelokaski & Maikki Siitari-Kauppi & Suvi Lamminmäki & jussi Ikonen Radiokemian laboratorio Kemian laitos Helsingin Yliopisto KYT2010 Kalliokulkeutuminen

2 Grimsel Test Site

3 Grimsel Test Site Investigations Phase VI Waste EBS Host-rock Interaction CFM Colloid Formation and Migration LCS Long Term Cement Rock Water interaction Geological Barrier Processes & Characterisation LTD Long Term Diffusion Engineered Barrier Systems (Long-term behaviour) FEBEX II Full-Scale Engineered Barrier Experiment 2001 NF-PRO Near Field Process/Lab Programme Training ITC Association ITC 2003 First training course 2003

4 LONG TERM DIFFUSION PROJECT Phase I Work Package 1: Monopole experiment An in situ diffusion experiment where RN-tracers diffuse into the rock matrix with subsequent geochemical analysis of matrix samples, combined with predictive and post mortem modelling exercises to increase confidence in the modelling of long-term and large-scale diffusion processes. Work Package 2: In situ porosity Characterisation of the pore space geometry, including determination of in situ porosity for comparison with laboratory-derived data, using the C-14 PMMA technique and the NHC-9 chemical porosimetry technique. Work Package 3: Natural tracer Study (NTS) A study of natural tracers in the rock matrix to elucidate evidence for longterm diffusion processes. Work Package 4: Diffusion Processes Study (DPS) Detailed characterisation of the flow paths in a water-conducting fracture and investigation of the in situ matrix diffusion paths in core material from earlier GTS experiments.

5 yhteistyökumppanit NAGRA -Sveitsi (National Cooperative for the Disposal of Radioactive Waste) AIST - Japani (Research Center for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology) JNC - Japani (Japan Nuclear Cycle Development Institute) NRI -Tsekki (Nuclear Research Institute Řež) Jyväskylän Yliopisto Fysiikan laitos Poitiersin Yliopisto, Hydrasa Ranska

6 kulkeutuminen kallioperässä Radionuclide transport in the geosphere Water conducting features (WCF s) Dominant transport process is advection Radionuclide retardation Dispersion within flow field Sorption on fracture / mineral surfaces Diffusion into fracture filling material (fault gouge) and the surrounding rock matrix (matrix diffusion,md) Retardation by MD Non-sorbing RN s: remain dissolved in immobile pore water Sorbing RN s: sorb onto inner surface of pores MI shear zone

7 D e K d ε = ε + ε + t f d ε r D = D e a ε e

8 Work Package 1: Monopole experiment

9 Nuclide Half life Activity [Bq] 3 H a 1.0E Na a 5.0E I 8.04 d 1.3E Cs a 5.0E+06

10 modelling Blind prediction exercises using different codes and approaches with slight variations in the conceptual model for matrix diffusion around a borehole. Institut de Ciències de la Terra Jaume Almera (CSIC), Spain Taisei Corporation (supported by JAEA), Japan Nuclear Research Institute Rez, Czech Republik University of Bern, Switzerland

11 ε a R C t = 1 r r rd e C r ε a RλC E-03 3 H C/C Ctot(Bq/m3rock)/C0(Bq/m3soltn) 6.0E E E E E E y 0.5 y 1.0 y 2.0 y E E E E E E E E t (days) x (cm) Cs C/C Ctot(Bq/m3rock)/C0(Bq/m3soltn) y 0.5 y 1.0 y 2.0 y E E E E E E E+03 t (days) x (cm) the concentration change in the test interval with time the tracer concentration in the rock matrix at different time steps during tracer circulation

12 Work package 2 -in situ porosity Compressed air Pressure sensor Pressure vessel with resin Data acquisition Scale Grain Ø 40 mm Resin a) Temperature sensor Data acquisition Heat regulating device Heating element Ø 16 mm b)

13 PMMA työt Grimselissä

14 Grimsel granite 10 cm

15 HYRL:n tavoite to devise a new application based on the PMMA method in combination with quantitative petrography tools for in situ rock matrix characterisation gain information on the reliability of laboratory-based rock characterisation methods by quantitative investigation on the effects of rock stress release on total and mineral-specific porosities to better understand diffusion in a heterogeneous rock matrix by new developed modelling tools

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17 tulokset pore types building an interconnected network : -Grain boundary pores mainly around quartz and feldspar grains -Sheet silicate pores in shear bands consisting of muscovite, biotite and chlorite -Microfractures (fine cracks) in large quartz and feldspar grains Pore distribution was found bimodal; pore apertures were around 300 nm and 20 µm PMMA porosity: in situ 0.6% compared to porosity at lab 0.9%

18 tulokset In situ 14 C-PMMA autoradiographic technique for rock matrix characterisation was developed Know how transfer within in situ experiments at underground rock laboratory Diffusion simulation using digitised autoradiograph images was done Interpretation of experiments using an inversion method to seek the local diffusion parameters was done One university thesis will be done in 2009

19 jatkossa LTD Phase II Dipole experiment

20 Kiitos!