29 reed synergies

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Donald ReedActinide Chemistry and Repository Science ProgramRepository Science and Operations (RSO)Los Alamos National LaboratoryMarcus AltmaierRadiochemistry DivisionKarlsruhe institute of Technology, Institute for Nuclear Waste Disposal7th US/German Workshop on Salt Repository Research, Design, and OperationWashington DC, September 6-9, 2016

Synergies Between Actinide/Brine Chemistry and Geotechnical Properties in a Salt Repository ConceptChemistry/Thermodynamic Database SummaryLA-UR-16-26635LA-UR 16- 21447LA-UR 15-27122

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Operated by the Los Alamos National Security, LLC for the DOE/NNSAOverviewRole/rationale for the Study of Actinide/Brine Systems in a Salt Repository ConceptRepository Design and Geotechnical Issues that Impact Actinide/brine ChemistryBrine Availability and Flow (Obvious)Redox-Active Waste/Barrier ComponentStrategy for Predictable/Favorable ChemistryUpdates on Actinide/Brine Chemistry ActivitiesNEA Pitzer SOAR and Salt ClubABC Salt (V) Workshop

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Operated by the Los Alamos National Security, LLC for the DOE/NNSASalt Repository Concept: Actinide ViewSafety case is most reliant on the geologic isolation expectedSelf-sealing in < 200 yearsLittle/no interconnected groundwater flowLow reliance on container/canister integrity in PAPerformance is somewhat independent of the wasteform/composition Favorable thermodynamics and chemistry can be achievedReducing conditions due to limited oxygen availability and designed reactivity of waste packageReactive redox control can be used to establish EhpH can be engineered to be mildly alkalineNo meaningful expectation of transport by diffusion or colloidal processes

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Operated by the Los Alamos National Security, LLC for the DOE/NNSA

Actinide Release Scenario and Calculated DBR ReleaseAppendix PA-2014DBR is dissolved brine releaseCombined E1E2 release is potentially highest release (but still low overall probability)In integrated release CCDF curves, DBR release is most important in the lower probability/high release part of the curve

E1E2 WIPP Deep Drilling Scenario for Release

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Operated by the Los Alamos National Security, LLC for the DOE/NNSARationale for Actinide/Brine Chemistry in a Salt Repository ConceptRegulatory reason (WIPP example): We are required to address all low probability scenarios in the safety case so it is a regulatory-driven requirement.

Sociopolitical reason: We should be able to explain what is likely to happen to the actinides/radionuclides at all times (before, during and after emplacement) for all repository scenarios. We need to show that the salt repository concept will work sufficiently well even if we are wrong about how the geology will function and what future societies may do. Site inundation with brine, regardless of how this occurs, likely defines the worse case scenarios.

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Operated by the Los Alamos National Security, LLC for the DOE/NNSAShould the Salt Repository Concept be Considered for HLW and SF Nuclear Waste?Current operational issues are an obstacle but the overall long-term safety case is not significantly impacted:WIPP fire and release incident (it was said there would never be any release from the WIPP)Asse brine seepage issues (it was said there would never be water/brine in a salt repository)HLW and SF will require that the overall safety case address the following (beyond TRU or LLW):Much of the WIPP safety case does apply so WIPP approach is a good but not sufficient template!Much greater and more diverse radionuclide inventory so more than Pu/Am is neededHigher temperature, so it is needed to show that this does not alter overall performance (leads to drier repository)Higher radiation levels, so this needs to be accounted for more extensively

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Operated by the Los Alamos National Security, LLC for the DOE/NNSABrine Availability and Flow (Obvious)Geotechnical issues that link to the availability, movement, and composition of water/brine are critical in defining the geochemical conditions:Temperature and pressureSelf-sealing and healing of fractured salt due to the waste emplacement process Water movement within and out/into the repositoryIntrusion scenarios and conceptual approach

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Operated by the Los Alamos National Security, LLC for the DOE/NNSAMobile Actinide/Radionuclide ConcentrationIn the WIPP concept, colloidal species contribute to the source term in dissolved brine release (DBR) release scenarios Colloidal transport is not a significant issueStructure and physical properties are not important solubility of the actinide that reflects pH, inorganic/organic complexationActinide concentration added due to colloidal speciesSolubilityMineralIntrinsicMicrobialHumic

Mobile actinide concentration(actinide source term)

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Operated by the Los Alamos National Security, LLC for the DOE/NNSADesign Input:Favorable Thermodynamics and Importance of Reducing ConditionsEstablished by repository design/conceptual modelSelf-sealing properties of saltMicrobial ecology and activityCorrosion/waste constituent reactionsFavorable thermodynamics provides higher assurance and reduced uncertainty with respect to repository performanceActinide speciation and solubility is lowered leading to greater immobilizationOverall source term description is simplified.

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Operated by the Los Alamos National Security, LLC for the DOE/NNSA

Plutonium Speciation (Altmaier/Neck INE)Best Example of Current Peer view

Provided curtesy of Marcus Altmaier (KIT/INE). This shows the current view of plutonium speciation for all possible conditions. For the WIPP, only the Pu(III) and Pu(IV) species apply (left side of the Figure).Altmaier, M., and H. Geckeis, Plutonium and Actinide Chemistry in Saline Solutions, Actinide Research Quarterly, 2011 (2), p. 29-32.

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Operated by the Los Alamos National Security, LLC for the DOE/NNSA

Pu-Fe Interaction Studies~ 10 year DataFe2+ is formed from the corrosion of Fe(0)Colloidal distribution is noted in the carbonate-borate pH area

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Operated by the Los Alamos National Security, LLC for the DOE/NNSAPossible Oxidation States for Actinides

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Operated by the Los Alamos National Security, LLC for the DOE/NNSADesign Input:Brine Chemistry that Favors Low Actinide SolubilityChemistry is defined by reaction of the brine with the waste and waste package components (so this can be controlled by design)Predictability is key/importantMildly alkaline conditions are ideal (pH 9-11)Provide assurance and reduce uncertainty with respect to repository performance

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Operated by the Los Alamos National Security, LLC for the DOE/NNSAWe need a good/comprehensive model for actinide solubility/concentrationCurrent repository and site specific thermodynamic data applications rely on estimations, approximations and simplifications done in a way to maintain conservatism with the model.Simplification can be easier to implement and more explainable to the regulator (therefore better defended)Circumvents data quality issues (that prevent its inclusion in the NEA databases)Account for site-specific gaps in data There are specific processes that are difficult to describe in thermodynamic terms Ultimately the driver for this activity is that it is the right thing to do scientifically (sociopolitical)

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Operated by the Los Alamos National Security, LLC for the DOE/NNSANEA Activities: Actinide and Brine ChemistryNEA TDB Pitzer State of the Art ReportLiterature survey to assess extent and completeness of available dataIdentification of data gapsRecommend consistency in data collection and analysisM. Altmaier1, D. Costa2, A. Felmy3, H. Moog4, R. Pabalan5, M. Ragoussi2, D. T. Reed6, W. Runde7, P. Thakur8, W. Voigt9

1) KIT-INE, 2) OECD NEA, 3) WSU, 4) GRS, 5) NWTRB, 6) LANL-CBFO, 7) LANL, 8) CEMRC, 9) TUBAFNEA Salt ClubIntegrated effort to establish a unified and self consistent set of Pitzer parameter and modeling approach

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Operated by the Los Alamos National Security, LLC for the DOE/NNSA

Specific Issues with High Ionic-Strength Thermodynamic dataThere is no rigorously thermodynamic approach available, so the Pitzer semi-empirical approach is usedLiterature assessment through the NEA is also in progress (State of the Art Report):

Number of Pitzer-evaluated binary and ternary system references sorted by oxidation state. (Altmaier/Fellhauer)several data gaps exist in current database applicationssignificant lack of ternary speciessignificant lack of temperature-variable data for the radionuclide/ actinide data set

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Operated by the Los Alamos National Security, LLC for the DOE/NNSASanta Fe NM, April 2013Proceedings of the Third International Workshop on Actinide and Brine Chemistry in a Salt-Based Repository (ABC-Salt III)

Carlsbad NM, September 2010Proceedings of the International Workshop on Actinide and Brine Chemistry in a Salt-Based Repository (ABC-Salt)

Karlsruhe, November 2011P