The RGT scientists apply broad expertise in geology, mineralogy, mineral physics, geochemistry, chemistry, and engineering to challenges in environmental contaminant transport, remediation and disposal with an emphasis on natural and synthetic radionuclide materials. Projects span scales from atomic-scale characterization of actinides to field-scale transport research. The team manages radiochemistry experimental laboratories with specialized equipment to study nuclide behavior at elevated temperatures and pressures. Combining experience in experimental, analytical, and modeling sciences, RGT produces comprehensive evaluations for environmental, energy, materials, and national security programs.

CAPABILITIES INCLUDE

• Spectroscopic investigations of contaminant speciation in the environment.
• Colloid characterization, microscopic visualization of colloid transport phenomena.
• Laboratory-scale contaminant and tracer transport experiments.
• Field-scale transport experiments involving solute and colloid tracers.
• Effects of microbes on contaminant transport.
• Measurements and interpretation of chemical and isotopic environmental tracers.
• High pressure, temperature (P/T) investigations of geochemical CO₂ sequestration.
• Elemental and isotopic characterization of radionuclides.
• Pore-scale characterization of shale for unconventional hydrocarbon production.
• High P/T synchrotron X-ray and neutron diffraction of materials.
• Thermodynamic measurements using various calorimetric techniques.

PRIMARY EXPERTISE

• Analysis of fluid- and subsurface fracture- related dynamics in carbon sequestration.
• Fabricating geologic pore networks to understand behavior under various simulated conditions.
• Application-focused characterization of geomaterials using advanced synchrotron X-ray and neutron techniques.
• Environmental remediation and restoration, analysis and project management.
• Performing geochemical analyses to enhance Earth System Models.
• Thermodynamics of solid phases and aqueous species.

RECENT MAJOR PROJECTS

Spent Fuel and Waste Storage & Transport: Studying the interaction of engineered barrier systems (EBS) in repository systems, nuclear waste form stability in repository pressure/temperature conditions, and hydrous mineral stability. Research includes:

• Investigations of argillite host-rock, EBS repository room chemistry.
• Clay studies for the Full-scale High Level Waste Engineered Barriers experiment and international collaboration.
• Steel corrosion, novel waste forms, interface mineral growth.

Brine Migration in Heated Salt: Understanding the source, chemical composition, and fate of brine produced from heated-bedded salt. This research addresses important knowledge gaps to improve predictive abilities for salt performance as a medium for permanent nuclear waste isolation.

• Collecting datasets to validate numerical models, improve constitutive and conceptual models.
• Conducting field data to improve understanding of acid gas generation.
• Ensuring continuity of knowledge, experience, in underground tests at WIPP.

Complex Fluids: Studying colloid and nanoparticle interactions and transport to understand and mitigate the migration of environmental contaminants and enhance the extraction of subsurface natural resources.

• Studying the properties of colloidal radionuclides and engineered nanoparticles.
• Manipulating natural and engineered colloid and nanoparticles in subsurface media to target-deliver particles or induce beneficial changes in subsurface media.

Experimental Study of Reactive Transport in Mesoporous Media: examining the complexity and heterogeneity of natural systems by describing transport and reactions at nanometers to micron scales. This research is fundamental for developing predictive tools for fluid-solid interactions in Earth’s crust and furthers DOE missions involving gas and oil extraction, carbon sequestration, enhanced geothermal systems, and long-term radioactive materials storage.

• Manipulating subsurface aquifers for isolation and immobilization.
• Characterizing mesoscale pore structures of geologic media and relevant evolution.
• Establishing relationship between mesoscopic pore transport and macroscopic properties of geologic media.

Pore Network Microfluids: performing micrometer-scale experiments on geologic formations at carbon sequestration sites to enhance long-term containment and energy security. Research targets critical phenomena to understand multiphase flow and reaction of carbon dioxide with brines and surrounding geologic substrates. Elements include:

• Facility design to fabricate pore network micromodels, conduct high P/T simulations.
• Characterizing flow patterns and variability of supercritical carbon dioxide in porous, brine-saturated media.

Advanced Geomaterials Characterization at High P/T: utilizing premier experimental techniques and sample environmental cells to characterize geomaterials and related processes for applications in geosciences, energy and environmental remediation.

• Fundamental and sophisticated characterization of large- and continuum-scale geological problems.
• Thermodynamic measurements of minerals/materials used for nuclear fuels, waste disposal and other applications.

Environmental Restoration: combining different forms of comprehensive analysis to develop robust hydrogeological conceptual models for transport of contaminants and evaluate remediation alternatives for field scale implementation.

• Project management for operations with large geological and geochemical aspects.
• Rapid-turnaround geochemical analyses to support real-time EP decision making.

Stable Isotope Geochemistry/Analytical Chemistry: characterizing stable isotopes for multidisciplinary national project to understand fractionations, and with forensic analyses application. Studies include:

• Isotope nuclear forensics, paleoclimate reconstruction.
• Noble gas geochemistry, tree rings and dendrochronology, floodplain sediments.
• Cave deposits, rare earth elements, and environments.

Uranium In-Situ Recovery (ISR): determining the long-term efficacy of remediation at post-mining aquifer sites restored through extraction technique that uses chemical leaching in saturated sedimentary rocks to dissolve minerals.

• Field testing to determine aquifer hydrologic and geochemical properties.
• Lab experiments, mineralogical, isotopic, and geochemical measurements.