The Center for Nuclear Waste Regulatory Analyses (CNWRA)
provides effective solutions to a wide range of hydrogeologic and geochemical problems.
Sophisticated computational and visualization resources and fully equipped laboratories
allow the CNWRA staff to solve diverse scientific and engineering problems for government
and industry.
The CNWRA is operated by Southwest Research Institute (SwRI),
an independent nonprofit research and development organization in operation for nearly 50
years. With 13 technical divisions, SwRI provides extensive resources, such as laboratory
facilities, analytical capabilities, and staff expertise in a broad range of scientific
and engineering specialties.
The CNWRA technical expertise includes:
- Physical and earth sciences
- Engineering and material sciences
- Hazard assessment
- Environmental science
- Regulatory interpretation, implementation, and compliance
demonstration
The Center offers expertise in the assessment and
interpretation of hydrologic flow and the consequent transport of environmental
contaminants in diverse geochemical systems.
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CNWRA scientists have developed a modeling approach
that identifies key chemical parameters to predict sorption behavior over a wide range of
conditions. This diagram shows the variation of U(6+) sorption on montmorillonite clay as
a function of solution pH and the ratio of solid-mass to solution-volume (M/V). The model
was calibrated against a series of CNWRA sorption experiments and extrapolated using the
Environmental Protection Agency code MINTEQA2 and a thermodynamic database prepared at
CNWRA.
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Numerical Modeling and Code Development
The CNWRA develops and applies numerical modeling codes for a
variety of computer systems. In addition to developing original geochemical and hydrologic
computer modeling codes, staff members have modified codes and used available codes to
meet client needs in:
- Multiphase isothermal and nonisothermal flow modeling
- Reactive contaminant transport calculation
- Infiltration analysis
- 3-D heterogeneity modeling
- Lagrangian particle tracking evaluation
- Perched water zone formation
- Sorption modeling
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This three-dimensional geological framework model of
Yucca Mountain, Nevada, integrates geologic, hydrologic, geochemical, and geomorphic data.
Integration of diverse data allows CNWRA scientists and engineers to effectively evaluate
complex process interactions that may affect contaminant transport.
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Field Investigations
The Center has conducted extensive field studies worldwide to
evaluate contaminant transport and to assess geologic structures, volcanologic effects and
hazards, and seismic risk.
CNWRA field expertise includes:
- Infiltration, permeability, and moisture measurements
- Regional and site-scale topographic mapping
- Surface and underground geologic mapping
- Rock, mineral, water, soil gas, and vegetation sampling
- Contact gamma radiation mapping
- Transient electromagnetic soundings for perched water zones
- Magnetometry surveys
- Radon measurements
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Using coupled moisture flux and energy balance
simulations, CNWRA scientists estimate hydrologic infiltration into fractured bedrock in
an arid environment, identifying areas of high infiltration (reds) and areas of lower
infiltration (blues). This example calculated infiltration as a function of climatic
parameters, hydraulic properties, alluvium depth, and erosion.
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Engineers predict contaminant concentration fields in
a two-layer, highly heterogeneous, unsaturated geologic medium using SUFLAT, a CNWRA
numerical code that performs stochastic flow and transport assessments.
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Laboratory Facilities
Extensive state-of-the-art laboratories are equipped for:
- Rock sample preparation and physical testing
- Saturated and unsaturated flow properties measurement
- Scale-model studies in environmentally controlled chambers
- Aqueous and solid-phase geochemical analyses (including natural
and synthetic radioactive materials)
- Microbiological studies
These facilities support understanding and problem resolution
in:
- Thermally driven moisture redistribution
- Mineral solubilities and ion exchange properties
- Mineral sorptive properties
- Radiochemistry
- Microbial viability and processes in earth materials
Regulatory Analyses
The Center analyzes various federal and state regulations and
prepares review methods and criteria to demonstrate or evaluate regulatory compliance. The
CNWRA regulatory experience includes working with:
- U.S. Environmental Protection Agency
- U.S. Mine Safety and Health Administration
- U.S. Nuclear Regulatory Commission
- U.S. Department of Energy
- U.K. Department of the Environment
- Swedish Radiation Protection Institute
This brochure was published in June 1995. For more information
about hydrogeology and geochemistry services, contact
Dr. English C.
Pearcy,
Manager, Geohydrology and Geochemistry Section,
Geosciences and Engineering, Southwest Research Institute, P.O. Drawer 28510,
San Antonio, Texas 78228-0510, Phone (210) 522-5540, Fax (210) 522-5155.
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