On the evaluation of groundwater contamination from underground nuclear tests

Abstract.Increasing concern about radioactive contamination of groundwater from underground nuclear tests has reinforced the need for a basic understanding of how the radionuclide inventories of such tests enter and migrate through groundwater. As a basis for studying these processes, the physically and thermally disturbed geologic environment produced by such tests and its relation to the post-test distribution of radionuclides is discussed from a conceptual perspective. These concepts are used to support the development of a reactive transport model to evaluate the nature and extent of radionuclide contamination within alluvium surrounding a specific underground nuclear test at the Nevada Test Site (NTS). Simulations are focused on determining the abundance and chemical nature of radionuclides that are introduced into groundwater, as well as the rate and extent of radionuclide migration and reaction in groundwater surrounding the working point of the test. Transport simulations based upon a streamline-based numerical model are used to illustrate the nature of radionuclide elution out of the near-field environment and illustrate the conceptual modeling process. The numerical approach allowed for relatively complex flow and chemical reactions to be considered in a computationally efficient manner. The results are particularly sensitive to the rate of melt glass dissolution, distribution of reactive minerals in the alluvium, and overall groundwater flow configuration. They provide a rational basis from which defensible migration assessments over larger spatial and temporal scales can proceed.

[1]  David K. Smith,et al.  The CHESHIRE Migration Experiment A Summary Report , 1999 .

[2]  A. F. B. Tompson,et al.  Reactive transport in heterogeneous systems; an overview , 1996 .

[3]  William L. Bourcier,et al.  Evaluation of the hydrologic source term from underground nuclear tests in Frenchman Flat at the Nevada Test Site: The Cambric test , 1999 .

[4]  J. S. Kahn,et al.  Phenomenology and containment of underground nuclear explosions , 1968 .

[5]  Martin J. Blunt,et al.  Streamline‐based simulation of solute transport , 1999 .

[6]  D. K. Smith,et al.  Migration of plutonium in ground water at the Nevada Test Site , 1999, Nature.

[7]  Steven F. Carle,et al.  Thermally Induced Groundwater Flow Resulting from an Underground Nuclear Test , 2000 .

[8]  C. W. Olsen.  Site selection and containment evaluation for LLNL nuclear events , 1993 .

[9]  Carl I. Steefel,et al.  Multidimensional, multicomponent, subsurface reactive transport in nonuniform velocity fields: code verification using an advective reactive streamtube approach , 1998 .

[10]  Martin J. Blunt,et al.  A 3D Field-Scale Streamline-Based Reservoir Simulator , 1997 .

[11]  M. Blunt,et al.  Simulating Flow in Heterogeneous Systems Using Streamtubes and Streamlines , 1996 .

[12]  J. B. Knox,et al.  Analysis of a groundwater anomaly created by an underground nuclear explosion , 1965 .

[13]  J. Thompson.  Radionuclide Distribution in a Nuclear Test Cavity: the Baseball Event , 1996 .

[14]  A. Hassan,et al.  Modeling Ground Water Flow and Radioactive Transport in a Fractured Aquifer , 1999, Ground water.

[15]  Ci Steefel,et al.  OS3D/GIMRT software for modeling multicomponent-multidimensional reactive transport , 2000 .

[16]  J. L. Thompson,et al.  Underground radionuclide migration at the Nevada Test Site , 1992 .

[17]  L. Gelhar.  Stochastic Subsurface Hydrology , 1992 .

[18]  J. F. Wild,et al.  The LLNL Nevada Test Side underground radionuclide source-term inventory , 1998 .

[19]  Robert D. Falgout,et al.  Analysis of subsurface contaminant migration and remediation using high performance computing , 1998 .

[20]  G. A. Pawloski,et al.  Development of Phenomenological Models of Underground Nuclear Tests on Pahute Mesa, Nevada Test Site - BENHAM and TYBO , 1999 .

[21]  David K. Smith.  Characterization of Nuclear Explosive Melt Debris , 1995 .

[22]  R. Nagle,et al.  Transport of Gaseous Fission Products Adjacent to an Underground Nuclear Test Cavity , 1996 .

[23]  William L. Bourcier.  Waste Glass Corrosion Modeling: Comparison with Experimental Results , 1993 .

[24]  W. W. Dudley,et al.  Radioactivity in the underground environment of the Cambric nuclear explosion at the Nevada Test Site , 1977 .

[25]  J. Thompson,et al.  Migration of Chlorine-36 and Tritium from an Underground Nuclear Test , 1988 .