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Project Concrete and Clay

Cement waste matrix evaluation and modelling of the long-term stability of cementitious waste matrices. Project Concrete and Clay. Lisa Almkvist and Börje Torstenfelt Swedish Nuclear Fuel and Waste Management Co (SKB) Peter Cronstrand Vattenfall Power Consultant (VPC). Background Aim

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Project Concrete and Clay

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  1. Cement waste matrix evaluation and modelling of the long-term stability of cementitious waste matrices

  2. Project Concrete and Clay Lisa Almkvist and Börje Torstenfelt Swedish Nuclear Fuel and Waste Management Co (SKB) Peter Cronstrand Vattenfall Power Consultant (VPC)

  3. Background • Aim • Modelling • Long term experiments • Laboratory experiments

  4. Background • KBS-3 cement during the construction phase • Degradation affects the ground water – affects the buffer material (bentonite)

  5. Background • SFR, SFL cement is used as a barrier • Degradation rate and factors that affects

  6. Barriers

  7. Aim • Cement’s properties - time • Cement – bentonite • pH information… • Describing the barriers • Development low-pH cement KBS-3 • Safety analysis – KBS-3, SFR, SFL

  8. Modelling • Thermodynamic modelling • 100 000 years • Equilibrium between different minerals • Ageing • invasion of anions, leakage of Ca2+ and OH- • Phreeqc-2.13 • enhanced with cement specific diffusivity-porosity relations • time dependent boundary conditions and temperature profiles • Mineral distribution, pH distribution, porosity distribution

  9. Long term experiment, Äspö Hard Rock Laboratory ~460 m

  10. Long term experiment • Long time perspective • Boundary conditions – realistic conditions • Set recipe for the cement • OPC, sulphate resistant, low-pH cement • Phase I: Installation • Holes in the rock with cement pillars • Phase II: Operation & Maintenance • Phase III: Analysis • ~ 2012 … 2045

  11. Labscale tests Ringhals Temperature changing cabinet Compressive and bending strength Curing time Fluidity Shrinkage

  12. Labscale tests Ringhals • Cement laboratory • Approx. 5-10 year perspective • Leaching • (Accelerated) ageing • Cement types • Mechanical stability

  13. Project timeline • Modelling • Initial modelling have started (spring 2008) • A few basic model simulations during 2009 • More in-depth after results from lab-scale and long-term experiments • Lab-scale tests • Startup spring 2009 (setting the experiments) • Analysis of first package approx. 2012 • Long-term experiment • Startup spring 2009 (setting the experiments) • Analysis of first package approx. 2014 • Analysis of last package approx. 2045

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