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

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 2

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 3

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 4

CBP Toolbox Development 5

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) 6

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 7

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

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

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 10

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

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

Impact: Uncertainty Reduction via Calibration of Thermodynamic Model Parameters PriorBest Fit Most prominent changes: Stratlingite, hydrogarnet and ettringite Al 14

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

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 16

Sulfate Attack Modeling 1.Transport of ions (saturated porous activity gradients) Driven by concentration and chemical activity gradients 2.Chemical Reactions Calculation of liquid-solid equilibrium and solid phase distribution using LeachXS/ORCHESTRA 3.Cracking Continuum damage mechanics model (Tixier and Mobasher, 2003) 4.Effect of cracking on diffusivity Relationships derived from fracture mechanics and numerical simulations (Krajcinovic et al., 1992) 17

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

Sulfate Attack – Probability of Complete Damage (Example Case) Complete damage (failure criteria): Time required for cracks to propagate through the entire structure Time to complete damage (years) Percentiles Case 1 S = 250 mM Case 2 S = 120 mM Case 3 S = 56 mM 5 th th th , th , th 1,8864,3546,120 19

CBP Example Problem: CO 2 and O 2 Ingress 3-Layer Reference Scenario Salt waste form (1) Concrete (2) Soil (3) 1000 cm20 cm50 cm CO 2 O2O2 3-Layer, 1-D diffusion model for reactive substances CO 2 and O 2 influx in soil layer proportional to partial pressure difference air-soil. 20

CO 2 Ingress & Carbonation Modeling for Tank Integrity and Closure Scenarios All CBP Partners Provide Unique Data Sources SIMCO Tech., Inc. experimental results for validation 21

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. 22

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). CBP Goal  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) Example Uses and Reference Cases Mechanistic / Phenomenological Basis Parameter Estimation and Measurement Boundary Conditions (physical, chemical interfaces) Uncertainty Characterization Basic Elements of the Performance Evaluation Long-term Structural, Hydraulic & Chemical Performance of Cementitious Materials & Barriers 23 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

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 For further information and reports 24