November 7, 2004

GSA Annual Meeting, Denver, CO

Russell L Jarek, Carlos F. Jove-Colon andCharles R. Bryan

Sandia National LabsAlbuquerque, New Mexico

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy’s National Nuclear Security Administration

under contract DE-AC04-94AL85000.

In-Drift Chemical Modeling – From Data to Abstraction

Overview of In-Drift Environment

Measurement and Test Data

Drift-Scale THC Physical & ChemicalEnvironment Models

Stratigraphy,Mineralogy

Repository Horizon Pore Water Chemistry

USGS: In-Drift Dust Leachate Chemistry

Multiscale TH

Overview from Data to Performance Assessment

Rock Thermal Properties

Measurement and Test Data

Multiscale TH Drift-Scale THC Physical & ChemicalEnvironment Models

EQ 3/6 with Pitzer Database

Potential Seepage Compositions

For Evaporative Evolution to Brine

Overview from Data to Performance Assessment

Measurement and Test Data

Multiscale TH Drift-Scale THC Physical & ChemicalEnvironment Models

EQ 3/6 with Pitzer Database

PA for License Application: Drip Shield and Waste Package DegradationWaste Form Degradation and Mobilization

· In-Drift Temperatures

· Relative Humidities

Local Chemical Environment (pH, I, [Cl−], [NO3

−])

Overview from Data to Performance Assessment

Drift-Scale THC Physical & ChemicalEnvironment Models

EQ 3/6 with Pitzer Database

Focus of In-Drift Details

Potential Seepage Compositions

Measurement and Test Data

Repository Horizon Pore Water Chemistry

PA for License Application: Drip Shield and Waste Package DegradationWaste Form Degradation and Mobilization

Yucca Mountain Pore Waters

5 Pore Waters Chosen to carry forward in THC analysis.

Ca + M

gSO4 +

Cl

Mg

Na+KCa CO3 Cl

SO4

• Units of % meq/l

Drift-Scale Thermohydrologic-Chemical Processes Modeled

Illustration; not to scale.

THC Results at Repository Drift Horizon

THC Potential Seepage Outputs

• Fracture Chemistries used for Crown Seepage– Evolution of parameters from starting pore waters

• P(CO2), pH, Na, K, Ca, Mg, SiO2, HCO3, Cl, NO3, F, SO4

• Al and Fe included from illite and hematite equilibrium

Drift-Scale THC Physical & ChemicalEnvironment Models

EQ 3/6 with Pitzer Database

Local Chemical Environment (pH, I, P(CO2), [Cl−], [NO3

−])

Focus of In-Drift Details

For Evaporative Evolution to Brine

Measurement and Test Data

PA for License Application: Drip Shield and Waste Package DegradationWaste Form Degradation and Mobilization

EQ3/6 Results with Pitzer Database

Compared with CRC Handbook data (81th ed., 2000) at 100ºC.

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Activity of Water

mas

s so

lute

/(m

ass

solu

te +

mas

s H

2O

1:1 MgCl2 + CaCl2

EQ3/6 (version 8.0)with new Pitzer DB

1:1 NaNO3 + Ca(NO3)2

1:1 CaCl2 + Ca(NO3)2

Scanning Electrodynamic Balance Experimental Data (evaporation): Choi and Chan (2002)

Compared with evaporation experimental data for prediction of aw.

Saturated Solutions Evaporation of Mixtures

•Do have problems with KNO3 at high temp. ORNL (D. Palmer) will conduct isopiestic experiments.

Na-Cl-Al(OH)4-SiO2-OH-Mg-NO3-Ca-SO4-H2O system; 25 to 140 C.

Evaporation and Deliquescence Processes

Example of Seepage Evaporation Result

Evolution to a Na/K-Cl/NO3 brine.

Minerals:Calcite, Halite, Fluorite, Amorphous Si, Thenardite, Nitrite, other minor.

Seepage Abstraction

• Take the THC Chemistry vs. Time Information

– Evaporate one water from each time step to 65% RH• This passes most chemical divides and reaches halite

– Group resulting water chemistries according to their aqueous compositions (results in 11 “bins”)

– The representative water for each bin is used in place of all the other waters from that bin

Representative Seepage Bin Compositions

Condition-Dependent Chemistry for PA

• Abstraction Allows for Condition-Dependent Chemical Representation– For each of the representative bin seepage waters:

• 3 Temperatures (40, 70, 100°C)

• 3 P(CO2) (10−2, 10−3, 10−4 bars)

• 2% RH increments, or less

– 99 Tables for TSPA-LA to sample from

Bin-History Map

• Outputs that feed directly to TSPA-LA

– Waste Package Degradation (Localized Corrosion)• Seepage chemistry parameters (P(CO2), pH, Cl, NO3)

• Dust deliquescence (P(CO2), pH, Cl, NO3)

– Waste Form Degradation and Mobilization• Invert chemistry parameters (pH, ionic strength)

In-Drift Physical and Chemical Environment

• Importance of In-Drift Water / Gas Chemistry in PA– Determining factor for potential localized corrosion

of waste packages

– Can affect invert radionuclide solubility

• Many Models and Data Contribute– Pore water and dust leachate analyses

– Drift-Scale Thermohydrologic Chemical Model to obtain starting composition and CO2(g)

– Pitzer database and EQ3/6 to evolve T and RH conditions

Summary

Acknowledgements

THC Model:Nicholas Spycher (LBNL)

Eric Sonnenthal (LBNL)

EQ3/6 Pitzer Database:Tom Wolery (LLNL)

Additional Thanks:Paul Mariner (Framatome)

Ernest Hardin (BSC)

Cliff Howard (SNL)

Darren Jolley