Post on 25-Jun-2020
Spent Fuel and Waste Science and Technology
Salt Disposal R&D:Field Test + Big Picture
Kris KuhlmanSandia National Laboratories
SFWST Annual Working Group MeetingLas Vegas, Nevada
May 22-24, 2018
Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. SAND2018-5424 PE
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
1) Salt R&D Programmatic Overview2) Salt Heater Test Overview
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Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Overall Goals of Salt R&D
Salt’s Benefits as a medium for disposal:– Impermeable to flow in far field (≤ 10−20 m2)– High thermal conductivity (~5 W
m⋅K)
– Relatively dry – Biologically simple– Creep closure and healing of excavations/fractures– Easily mined via continuous miner
Where to Contribute to Salt Technical Basis?– Disposal of heat-generating waste vs. WIPP– Bedded vs. domal salt
Contribution to Long-Term PA– m-scale behavior over days/weeks is PA initial condition– Brine availability impacts corrosion & transport
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Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Recent Salt Field Test History
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DOE-EM planned Disposal Demonstrations planned at WIPP– DOE-Environmental Management (DOE-EM) Carlsbad Field Office runs WIPP
– Salt Disposal Investigations (SDI) – 2011 (hot alcove-style disposal demo)
– Salt Defense Disposal Investigations (SDDI) – 2013 (cooler in-drift disposal demo)
DOE-NE Salt R&D Albuquerque Workshop (March 27, 2013)
– SNL, LANL, LBNL, DOE: salt field experiments consistent w/ UFD roadmap
DOE-EM work on SDI/SDDI stopped (Feb 7, 2014)
DOE-NE Small-scale (phased) testing approach at WIPP
– 2014 DOE-NE ramps down generic modeling and laboratory work on salt
– 2014-2016: morphed from drift-scale demonstration to borehole-scale test
– Small-scale borehole heater test designed in FY17 (SNL/LANL/LBNL)
– Small-scale borehole heater test implementation beginning June 2018
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt R&D in Safety Case
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SDI/SDDICurrent PlannedField Tests
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt R&D Gaps: 2012 UFD Roadmap
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2012 UFD Roadmap Document– Five of top 6 high-priority FEPs (Appendix B) are on Salt [score]
1. 2.2.01.01 – Evolution of Clay/Shale EDZ [8.00]
2. 2.2.08.01 – Flow through salt host rock [7.73]
3. 2.2.08.02 – Flow through other geologic units near salt repository [7.73]
4. 2.2.08.06 – Flow through the salt EDZ [7.73]
5. 2.2.08.04 – Effect of repository excavation on flow in salt host rock [7.10]
6. 2.2.08.07 – Mineralogic dehydration of salt [6.49]
These FEPs rated “High: information essential to decisions” – Site Selection
– Site Characterization
– Site Suitability
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt State of the Art: 2012 UFD Roadmap
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2012 UFD Roadmap Document: “State of the Art” for key FEPs– Need to understand fracturing and healing in clays and salt.
– Water migration in salt is a unique process that needs to be better understood. Need to understand thermal and pressure gradients and gas generation and migration.
– Need to know the evolution of the characteristics of the EDZ under the thermal-mechanical and wetting changes (clay and salt).
– Need to understand the coupled evolution of near-field host rock (EDZ) and backfill.
– Considerable work has been done for WIPP and European programs.
– European programs starting multi-year projects investigating thermal-mechanical and moisture effects in the EDZ.
– This issue includes other disturbances (e.g., ventilation) beyond just excavation effects.
2012 UFD Roadmap “take-away message” regarding Salt– Brine migration (+ventilation dry-out) needs to be better understood
– THMC Evolution of EDZ is complex, but important
– Significant existing international field testing database exists
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt R&D Priorities
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Salt R&D is focused on field test– Shakedown heater test in existing boreholes (now)
– Heater test in new built-for-purpose boreholes (later this FY)
– Larger scale follow-on demonstrations
Salt R&D Modeling/Lab Efforts Support field test– Numerical modeling to design and interpret results of field test
• LANL (FEHM) & LBL (TOUGH-FLAC)
– Laboratory testing to analyze brine/gas/solid samples collected during field test
• SNL (solids and liquids) & LANL (liquids and gases)
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt R&D Priorities
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Salt R&D Lab Efforts for Liquid Samples (SNL)– Analysis of brines not trivial, requires significant dilution and
there is interference between ions
– Using Ion Chromatograph (IC) & Inductively Coupled Plasma Optical Emission Spectrography (ICP-OES)
Salt R&D Lab Efforts for Solid Samples (SNL)– Pore space and mineralogy characterized via Zeiss X-ray microscope
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Integration with GDSA/PA & Safety Case
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Developments for GDSA are lower priority in Salt R&D (FY18)– Numerical modeling to design/interpret tests takes priority
GDSA and PA potential contribution areas for Salt– Pitzer model needed to do “full chemistry” in salt (using EQ3/6 now)
– Other chemistry → fluid flow coupling effects with brine
• FEHM implements some of these now (e.g., vapor-pressure lowering)
• Implementing analogous features in PFLOTRAN is possible
– EDZ development and evolution is especially important in salt
• TOUGH-FLAC implements these now
• Moving features from TOUGH-FLAC to PFLOTRAN is difficult / requires “response surface” for PA
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Integration with International
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Upcoming US/German Salt Repository Workshop– September 2018 in Hannover, Germany
– Same week/location as SaltMechIX conference
– NEA Salt Club meeting Friday before in Braunschweig, Germany
– WEIMOS geomechanical benchmarking meeting (SNL/BGR/IfG)
Field Test Design shared at 2017 US/German workshop
Increased exposure of test with foreign partners– Experimental data useful to German/Dutch/British repository programs
– More involvement with foreign partners in future design/interpretation
– Future WEIMOS-like US/German collaboration on seals (Matteo)
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt Disposal R&D Five-Year Plan
Small-Diameter Borehole Heater Test (SDBHT)– FY17-18 test plan / late FY18 begin execution– Isothermal test & 120 °C test in existing holes– Re-design for follow-on heated tests
Other Possible Tests in “Out Years”– Further SDBHT configurations – Intermediate-scale testing
1. Large-scale granular salt reconsolidation2. Shear testing3. Single-canister thermal test
Laboratory/Modeling Investigations– Only those supporting field investigations
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(1)
(2)(3)
(SDBHT)
Salt Host Rock Integration Pyramid
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Waste Form (WF)
EBS Buffer/Backfill Host Rock
Was
te P
acka
ge(W
P)
ENGINEERED BARRIER SYSTEM (EBS) GEOSPHERE
THCMBR Processes
Radionuclide (RN) Transport
BIOSPHERE
Biosphere (and Surface)
[SNF][HLW]
[BENTONITE] [GRANITE]
NEAR FIELDSOURCE FAR FIELD RECEPTOR
Seal
s/Li
ner
Aquifer
Source Term RN Inventory WF Degradation WP Degradation
Receptor Dilution Water
Consumption Dose Conversion
Factors
Near-Field and Far-Field Buffer Degradation DRZ Evolution Chemical Interactions Thermal Effects
Advection Diffusion Sorption RN Decay and
Ingrowth
Dist
urbe
d Ro
ck
Zone
(DRZ
)
Processes
Lab & Field Experiments
Subsystems
ModelsTHC Moisture Redistribution
in Backfill (heat pipe)THM Drift Creep Closure / DRZ
Healing
Waste Form/ PackageDegradation
In Situ Brine
AvailabilityLab Salt Heat Pipe / Dry Out
Lab Acid Gas Generation
In Situ Shear Test
In Situ SaltReconsolidation
Heated Borehole Closure
“Single Canister” In Situ Heater Test
[Run of Mine Salt]
[Salt]
THMC → GDSA Initial Conditions (saturation) and EDZ distribution
Radionuclide Transport
Full Chemistry Reactive Transport (including Pitzer)
Backfill Reconsolidation
THMC BackfillReconsolidation
Drift-ScaleHeater Test
SDBHT (Phase 1)In Situ Testing Options
(Phase 2)
Drift-Scale(Phase 3)
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018 14
1) Salt R&D Programmatic Overview2) Salt Heater Test Overview
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
SDBHT Executive Summary
Goals of Small-Diameter Borehole Heater Test (SDBHT)– Brine availability, brine transport, brine composition, and gas evolution– Collect datasets for:
• Validating numerical models• Populating constitutive models
– Get back underground, gain hands-on experience Straightforward Modular Design
– Central test borehole (4”-6” diameter, ≤6 m long, ≤2 m test interval)– Satellite observation boreholes (1”-2” diameter)– Packer-isolated test interval– Test repeated at target temperatures (30, 50, 120, 160 & 200 °C)
Horizontal Test Orientation– Avoids mapped clay, polyhalite, or anhydrite layers– Interval completed in single geologic unit (MU-0 at WIPP)
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Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
SDBHT Phased Approach (1) Packer inflation tested in Existing Borehole (Feb 2018) Heated “Shakedown” tests in Existing Boreholes (June 2018) Packer, Heater, Gas Circulation System & Borehole Closure
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Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
SDBHT Phased Approach (2) New Boreholes to be drilled in 2018
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~Test target elevation
Existing Borehole location
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Horizontal Bedded Salt Heater Test
Previous WIPP heater tests crossed significant clay layers Clay layers dominated response (especially ≥100 °C) Without clay/anhydrite, salt DRZ is main source of permeability
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Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Testing Outside Access Drift DRZ
Test interval should be outside access drift DRZ Test borehole DRZ should be main source of perm / porosity
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Damagemodeling
Damageobservations
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Brine Composition Expectations
Brine collects in borehole H2O removed with dry N2 Brine composition evolves
– Initially precipitates halite– Becomes Mg & K rich
3 primary brine sources– Intergranular (pores)– Intragranular (inclusions)– Hydrous Minerals
Different brine sources have variable composition– Competing effects on observed
brine composition– EQ3/6 modeling to interpret
observations– Experiments to validate
approach
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K+/Mg++
Na+
/Cl-
Intergranular brine
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Gas Composition Expectations
Gases from thermal decomposition of:– Volatiles in salt (e.g., hydrocarbons at Asse)– Gases trapped in fluid inclusions– Dissolved gas in brine– Rubber (silicone, neoprene & viton) components in seals and packers
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Water from brine– Natural H2O– D2O tracer
Acid gas from salt/brine– Decomposition of solid hydrous
Mg salts into MgO + HCl– Equilibration of PHCl(g) into
condensed steam from strong brines (especially Mg-Cl brines)
– Very low pH observed (≤1)– Acid may cause further
component decomposition
Site 1 (~195°C)
Coyle et al. (1987) BMI/ONWI-624
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Brine Inflow Expectations
Brine inflow rate– Highest immediately after drilling– Exponential decay
Higher brine inflow at higher T– Especially from clay above 100°C
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Isothermal brine inflow at WIPP in MU-0
Vertical WIPP boreholes (Clay F)
50°C
130°C
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
SDBHT Test Design
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Tests In New Boreholes• Monitor Water Inflow• Sample Gases• Sample Liquid Brine• Geophysics:
• ERT• Acoustic Emissions• Temperature
Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
SDBHT Project Plan
Project Plan Document developed in April 2018 Responsibilities of Participants in Project
– SNL: Project Management, Brine Sampling, Brine & Solids analysis, Borehole Closure, Acoustic Emissions, EBS
– LANL-Carlsbad: WIPP Underground Test Coordination Office– LANL: Heater Design/Control, Gas Handling, Packers, THC
modeling (FEHM), Brine & Gas analyses– LBL: Electrical Resistivity Tomography, Fiber-optics based
Observations, THM modeling (TOUGH-FLAC)– WIPP M&O Contractor (Nuclear Waste Partnership): Coring,
Site ES&H, Site access & power
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Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt R&D Session Summary
Remainder Salt R&D Session
~10 minute lightning talks– Doug Weaver (LANL): WIPP Support and Logistics– Phil Stauffer (LANL): Update on Salt Disposal R&D– Jonny Rutqvist (LBL): Update on Salt Disposal R&D– Melissa Mills (SNL): Laboratory Brine Evap. Studies– Peter Johnson (LANL): Coupled THC Processes in Salt– Yuxin Wu (LBL): Geophysics in Heater Test– Ed Matteo (SNL): International / EBS / Sealing
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Spent Fuel and Waste Science and Technology
Salt R&DMay 23, 2018
Salt R&D Team (SNL/LANL/LBL) – Working towards a single common goal for several years– Implementing borehole heater field test at WIPP this summer
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