The Cementitious Barriers Partnership: Predicting the Long-term Chemical and Physical Performance of Cementitious Materi

1. The Cementitious Barriers Partnership:Predicting the Long-term Chemical and Physical Performanceof Cementitious Materials used in Nuclear Applications K. G. Brown (Presenter); CRESP, Vanderbilt U. D. Esh, M. Fuhrmann, J. Phillip; US NRC D. Kosson, S. Mahadevan, A. Garrabrants, S. Sarkar, J. Arnold; CRESP, Vanderbilt U. H. Van der Sloot†, J.C.L. Meeussen‡, P. Seignette, R. Comans; ECN (NL) E. Garboczi, K. Snyder, J. Bullard, P. Stutzman; NIST E. Samson, J. Marchand; SIMCO Technologies, Inc. (CA) C. Langton, G. Flach, R. Seitz, S. Marra, H. Burns; SRNL DOE-EM Project Manager: Pramod Mallick 29 November 2011 †Hans van der Sloot Consultancy after 01JAN2010 ‡NRG after 01SEP2010

2. Project Goal • Develop a reasonable and credible set of tools to predict the structural, hydraulic and chemical performance of cement barriers used in nuclear applications over extended time frames (e.g., up to or >100 years for operating facilities and > 1000 years for waste management). • Mechanistic / Phenomenological Basis • Parameter Estimation and Measurement • Boundary Conditions (physical, chemical interfaces) • Uncertainty Characterization

3. Partnership Members • Department of Energy – Office of Environmental Management • Scenarios & Key Uncertainties • Primary end-user • Nuclear Regulatory Commission • Scenarios & Key Uncertainties • Primary end-user • Savannah River National Laboratory • Performance Assessment (PA) Interface • Model Integration • Cracking Scenarios • Test Beds • NIST • THAMES – Microstructure Evolution & Properties • SIMCO Technologies, Inc. • STADIUM® – Physical & Hydraulic Performance • Energy Research Centre of the Netherlands (w/ Nuclear Research Group, Hans van der Sloot Consultancy) • LeachXS™/ORCHESTRA – Chemical Performance & Constituent Release • Vanderbilt University/CRESP • Chemical Performance & Constituent Release (experimental) • Uncertainty Analysis Framework • Model Integration

4. Technical Strategy / Approach • Reference Cases – provide basis for comparison and demonstration of tools under development • Cementitious waste form in concrete disposal vault with cap • Grouted high-level waste (HLW) tank closure • Spent fuel pool • Nuclear processing facilities closure / D&D (e.g., canyons) • Grouted vadose zone to immobilize contamination • Materials – surrogate low-activity waste (LAW) cementitious waste form, reducing grout, reinforced concrete (historical), and reinforced concrete (future) • Extension/enhancement of existing tools – CEMHYD3D/THAMES, STADIUM®, LeachXS™/ORCHESTRA, GoldSim Performance Assessment (PA) framework • Coordinated experimental and computational program • Conceptual model development and improvement • Define test methods and estimate important parameters • Model calibration and validation

5. CBP Toolbox Development

6. Integration of CBP Tools with PAs • CBP Focus: • Cementitious materials performance as part of engineered system and their interfaces with natural system • To provide near field source term • Uncertainty approach being developed to be broadly applicable to PA and design process CBP Interest Area Landfills Partnership (CRESP) Craig Benson (U of Wisconsin)

7. Key Degradation Phenomena Phenomena • Chloride ingress & corrosion • Leaching • Sulfate attack & cracking / damage (2011) • Carbonation (2012) • Oxidation (2012) • Cracking (2013) • Pore structure relationships with mass transfer and hydraulic properties (TBD NIST) Integration with Conceptual Models • Coupled degradation phenomena • Saturated, unsaturated and variable saturation • Liquid, vapor mass transfer • System geometry and boundary conditions

8. Specifications, Properties, and Phenomena for the Evaluation of Performance of Cementitious Barriers

9. Linking Prototype Cases to Performance Models through System Abstraction GoldSim & ASCEM

10. CBP Progress and Impacts • Demonstrated coupling of LeachXS™/ORCHESTRA and STADIUM® with GoldSim (using a Dynamic-link Library / DLL) • Understanding potential for sulfate attack during salt waste disposal in a concrete vault • Supporting DOE-ORP Secondary Waste treatment evaluation • Participation in inter-laboratory validation of draft EPA leaching test procedures • Data for evaluation of environmental impact of fly ash usage in cementitious materials (grout, concrete, etc.) – input into EPA regulatory process

11. Software integration objectives: Provide a common, unified interface to CBP partner codes through a GoldSim Graphical User Interface (GUI) Provide a “wrapper” for probabilistic uncertainty / sensitivity analysis (e.g., Monte Carlo) Couple LeachXS™/ORCHESTRA, STADIUM® and THAMES in a synergistic manner Connect to broader systems-level performance, safety and environmental assessment models

13. Impact: Comparison of Cement Data and Thermodynamic Model Predictions Experimental data from USEPA Draft Method 1313

14. Impact: Uncertainty Reduction via Calibrationof Thermodynamic Model Parameters Prior Best Fit Al Most prominent changes: Stratlingite, hydrogarnet and ettringite

15. Impact: Influence of Cement Type on Damage Ettringite and Gypsum Profiles Damage Fronts • Damage depends on both ettringite and gypsum formation; primary damage observed from ettringite for Type I and from gypsum for Type V cements.

16. CBP Example Problem: Salt Waste Disposal System Integrity • Summary of Results for Sulfate Attack • Ability to model sulfate attack and resulting damage based on concrete type (cement type, physical properties) and external sulfate concentration • Probabilistic analysis for both model and parameter uncertainty • Resulting models and parameters can be used for evaluation of a range of similar materials and scenarios • Impact • Allows selection of design parameters and materials to insure long-term durability and meeting performance goals • Results can be integrated into existing performance assessment fate and transport models

17. Sulfate Attack Modeling • Transport of ions (saturated porous activity gradients) • Driven by concentration and chemical activity gradients • Chemical Reactions • Calculation of liquid-solid equilibrium and solid phase distribution using LeachXS/ORCHESTRA • Cracking • Continuum damage mechanics model (Tixier and Mobasher, 2003) • Effect of cracking on diffusivity • Relationships derived from fracture mechanics and numerical simulations (Krajcinovicet al., 1992)

18. Sulfate Attack Modeling Framework Leaching out of Ions Diffusion of Ions Chemical Reactions Volume Change • Damage Assessment • Elastic Properties • Strength Change in Porosity Strain Cracking Damage Parameter Change in Diffusivity

19. Sulfate Attack – Probability of Complete Damage (Example Case) Complete damage (failure criteria): Time required for cracks to propagate through the entire structure

20. CBP Example Problem: CO2and O2 Ingress3-Layer Reference Scenario • 3-Layer, 1-D diffusion model for reactive substances • CO2 and O2 influx in soil layer proportional to partial pressure difference air-soil. Salt waste form (1) Concrete (2) Soil (3) CO2 1000 cm 20 cm 50 cm O2

21. CO2 Ingress & Carbonation Modeling for Tank Integrity and Closure Scenarios All CBP Partners Provide Unique Data Sources SIMCO Tech., Inc. experimental results for validation

22. LEAF Leaching Methods Method 1313 – Liquid-Solid Partitioning as a Function of Eluate pH using a Parallel Batch Procedure Method 1314 – Liquid-Solid Partitioning as a Function of Liquid-Solid Ratio (L/S) using an Up-flow Percolation Column Procedure Method 1315 – Mass Transfer Rates in Monolithic and Compacted Granular Materials using a Semi-dynamic Tank Leaching Procedure Method 1316 – Liquid-Solid Partitioning as a Function of Liquid-Solid Ratio using a Parallel Batch Procedure Note: Incorporation of these methods into SW-846 is ongoing; titles and method identification numbers are subject to change.

23. CBP Goal Develop a reasonable and credible set of tools to predict the structural, hydraulic and chemical performance of cement barriers used in nuclear applications over extended time frames (e.g., up to or >100 years for operating facilities and > 1000 years for waste management). Mechanistic / Phenomenological Basis Parameter Estimation and Measurement Boundary Conditions (physical, chemical interfaces) Uncertainty Characterization • Cementitious waste form in concrete disposal vault with cap (↔ Landfills Partnership) • Grouted high-level waste (HLW) tank closure • Spent nuclear fuel pool integrity • Nuclear processing facilities closure / D&D • Grouted vadose zone to immobilize contamination • Materials – surrogate low-activity waste (LAW) cementitious waste form, reducing grout, reinforced concrete (historical) and reinforced concrete (future) Long-term Structural, Hydraulic & Chemical Performance ofCementitious Materials & Barriers Basic Elements of the Performance Evaluation Example Uses and Reference Cases Being Completed • CBP Coordinated Experimental and Computational Program • Develop and improve conceptual models • Define test methods and estimate important parameters • Calibrate and validate models and perform probabilistic analyses

24. FY2012 CBP Focus • End-user licensing and training • High-level waste (HLW) tank integrity and closure • Carbonation rate as key to external attack • ASCEM source term demonstration case www.CementBarriers.org For further information and reports