Page 1 Dr. Frank Bok | Institute of Resource Ecology | A brief comparison of Pitzer databases for nuclear waste disposal modeling Actinide and Brine Chemistry in a Salt Repository Workshop (III) Santa Fe, 2013/04/15-17 F. Bok (HZDR), W. Voigt (TUBAF), Ch. Bube (KIT-INE), St. Wilhelm (AF Consult), H. Moog (GRS)

Page 2 Dr. Frank Bok | Institute of Resource Ecology | …and compared with other Pitzer databases?  Available Pitzer databases concerned in this study  Necessary code-specific database transformations  Comparison of example calculations

Page 3 Dr. Frank Bok | Institute of Resource Ecology | Transformation into Geochemist’s Workbench format Available Pitzer databases vs. geochemical codes: PHREEQC Q*Q* EQ3/6 GWB ChemApp thermo_hmw.dat thermo_phrqpitz.dat pitzer.dat data0.ypf.R0 ‒ 2* THEREDA R2 ‒ R6 THEREDA R1 data0.hmw.R2 polytherm data 25 °C data only Q* = Quintessa

Page 4 Dr. Frank Bok | Institute of Resource Ecology | PHREEQC: analytical equation for logK(T) Halite NaCl = Cl- + Na+ log_k analytic GWB: logK(T) grid Halite type= halide formula= NaCl mole vol.= cc mole wt.= g 2 species in reaction Na Cl same situation for transformation from PHREEQC to EQ3/6 formalism T = 0 °C 25 °C 60 °C100 °C 150 °C200 °C250 °C300 °C A 1 A 2 A 3 A 4 A 5 Database transformations due to different logK(T): Interpolation: Source of inaccuracy

Page 5 Dr. Frank Bok | Institute of Resource Ecology | Temperature function implemented in THEREDA: Temperature function implemented in EQ3/6 (Version 8.0):  It is not possible to convert THEREDA’s six-term temperature function correctly into the current EQ3/6 equation. New problem: temperature function for Pitzer parameters:

Page 6 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  Oceanic salt system: 25°C °C o Na +, Cl −, SO 4 2− – H 2 O o K +, Mg 2+, Cl − – H 2 O o K +, Mg 2+, SO 4 2− – H 2 O  Nd(III) in Na +, Mg 2+, Ca 2+, Cl − – H 2 25 °C o Solubility of amorphous Nd(OH) 3 in 3.86 m CaCl 2 solution  Np(V) in Na +, Cl − – H 2 25 °C o Solubility of fresh amorphous NpO 2 (OH) in 1.0 m NaCl solution  Cs in Oceanic salt 25 °C o Cs +, Na +, SO 4 2− – H 2 O  Cement 25 °C: o Solubility of C2AH8 + C4AH13 (Ca 2 Al 2 (OH) 10 · 3 H 2 O) + Ca 4 Al 2 (OH) 14 · 6 H 2 O)

Page 7 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The system Na +, Cl −, SO 4 2− – H 2 25 °C:  pitzer.dat / thermo_phrqpitz.dat: No Thenardite data

Page 8 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The system Na +, Cl −, SO 4 2− – H °C:  pitzer.dat (PHREEQC) / thermo_phrqpitz.dat (GWB): The lack of Thenardite data becomes critical!

Page 9 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The system K +, Mg 2+, Cl − – H 2 25 °C:  Only small deviations at the invariant points

Page 10 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The system K +, Mg 2+, Cl − – H °C:  pitzer.dat / thermo_phrqpitz.dat: No log 10 K for Carnallite for T ≠ 25 °C

Page 11 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The system K +, Mg 2+, SO 4 2− – H 2 25 °C:  two different log 10 K values for Epsomite can be found in data0.ypf.R0  other log 10 K differences between the databases are not significant

Page 12 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The system K +, Mg 2+, SO 4 2− – H °C:  Langbeinite data  pitzer.dat: Temperature dependency not for every mineral (e.g. Kieserite)  thermo_phrqpitz.dat: Same 25°C-log 10 K for all temperatures if temperature dependency is missing (e.g. Kieserite, Pentahydrite)

Page 13 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The solubility of fresh amorphous NpO 2 (OH) in 1.0 m NaCl 25 °C  Highly different log 10 K values of Np(V) hydrolysis species:

Page 14 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  Solubility of amorphous Nd(OH) 3 in 3.86 m CaCl 2 25°C o Nd as analoq for most trivalent actinides   Anionic Nd(III) complexes e.g. Nd(OH) 4 −, or ternary complexes e.g. Ca 3 [Nd(OH) 6 ] 3+

Page 15 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  The system Cs +, Na +, SO 4 2− – H 2 25 °C: o No solid solutions (as e.g. in the system Cs +, K +, Cl − – H 2 O) o No double salts (as e.g. in the system Cs +, Mg 2+, SO 4 2− – H 2 O) o Enough data from literature  log 10 K values for Cs containing minerals

Page 16 Dr. Frank Bok | Institute of Resource Ecology | Comparing calculations:  Cement 25 °C: o Solubility of C2AH8 (Ca 2 Al 2 (OH) 10 · 3 H 2 O) + C4AH13 (Ca 4 Al 2 (OH) 14 · 6 H 2 O)

Page 17 Dr. Frank Bok | Institute of Resource Ecology | Conclusions & Outlook  There is no “perfect” database that fits all needs.  Always check first: o Data for all possible species and phases o Temperature dependence of log 10 K values & ion-ion interaction parameters o Validity limits of the given data (Temperature, pH, Ionic Strength, Pressure)  Establish mutual Benchmark activities including different institutions o More diverse examples depending on the partners purposes o Include more geochemical codes and compare with measured values  Identify data lacks and less reliable data  Enhance databases quality  Increase confidence in modeling results Conclusions: Outlook:

Page 18 Dr. Frank Bok | Institute of Resource Ecology | Special thanks to: THEREDA is jointly funded by the Federal Ministry of Education and Research (BMBF), the Federal Ministry of Economics and Technology (BMWi), and the Federal Office for Radiation Protection (BfS) with funds from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU).  Thomas J. Wolery  Craig M. Bethke Funding: Acknowledgments

Page 19 Dr. Frank Bok | Institute of Resource Ecology | Visit us on: Thank you very much!

Page 20 Dr. Frank Bok | Institute of Resource Ecology | COST Action (EU + Associates)  COST-Proposal, submitted March, 27: THERmodynamic Modelling DataBase NETwork (THERMODB-NET)  Objectives:  Boost the quality and comparability of databases and modeling results necessary for earth systems modeling  Improvement of the quality of country-specific databases securing comprehensiveness and precision of model scenarios  Synchronization of data evaluation and processing schemes to establish internationally agreed quality assurance criteria  Enabling consistent, comprehensive and transparent thermodynamic data exchange  Identify methodologies for mineral-water interface data storage, collection and digitization  Preliminary partners in proposal  Germany (THEREDA, coordination HZDR)  Belgium (SCK-CEN)  GB (NDA)  France (ANDRA )  Switzerland (PSI)  USA (…)  more partners are welcome!

Page 21 Dr. Frank Bok | Institute of Resource Ecology | PHREEQC to GWB format transformation check: CodeCa 2+ T [molal][°C] PHREEQC1.5522E GWB1.547E Difference0.34%0.4 Anhydrite + Gypsum Example 2 from the PHREEQC manual 1 : Equilibrium temperature of Anhydrite and Gypsum  Comparison between PHREEQC and Geochemist’s Workbench (GWB) 1 Parkhurst, D.L., Appelo, C.A.S.; Water-Resources Investigations Report , (1999), p. 203.

Page 22 Dr. Frank Bok | Institute of Resource Ecology | EQ3/6 to GWB format transformation check: Example 3 from WIPP report 2 : Solubility of Gypsum in a Saturated NaCl Solution 2 Leigh, C.D.; WIPP Verification and Validation Document for EQ3/6 Version 8.0a for Actinide Chemistry Document Version 8.10 ERMS #550239, (2010), p. 37. CodeNa + Ca 2+ [molal] EQ3/ GWB Difference0.08%1.03% Invariant point Halite + Gypsum  Formation of Anhydrite was suppressed

Page 23 Dr. Frank Bok | Institute of Resource Ecology | Comparing the codes with identical database Scenario :  Invariant points and saturation curves in the ternary system Na +,Cl −,CO 3 2− – H 2 O at 25 °C  THEREDA R3 database CodeCl − CO 3 − [mol/kg] PHREEQC EQ3/ GWB ChemApp Difference1.15%1.06% Invariant point: Natron + Na 2 CO 3 · 7 H 2 O

Page 24 Dr. Frank Bok | Institute of Resource Ecology | Comparing the codes  THEREDA:documented test calculations of identical scenarios with all four geochemical codes for every data release 

Page 25 Dr. Frank Bok | Institute of Resource Ecology | Comparing the codes – Na +, Cl −, SO 4 2− – H °C

Page 26 Dr. Frank Bok | Institute of Resource Ecology | Comparing the codes – K +, Mg 2+, SO 4 2− – H °C

Page 27 Dr. Frank Bok | Institute of Resource Ecology | Comparing the codes – K +, Mg 2+, SO 4 2− – H °C

Page 28 Dr. Frank Bok | Institute of Resource Ecology | Comparing the codes – Np(V)  The Solubility of fresh amorphous NpO 2 (OH) in 1.0 m NaCl 25 °C

Page 29 Dr. Frank Bok | Institute of Resource Ecology | Comparing the codes – Nd(III) Limited by GWB