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Results from exploratory drill hole UE2ce, Northwest Yucca Flat, Nevada Test Site, near the NASH Event

Description: Exploratory drill hole UE2ce was drilled in January 1977 to determine geologic and geophysical characteristics of this site. This report presents geophysical logs, lithology, geologic structure, water table measurements, and physical properties for this drill hole. The data are then extrapolated to the NASH site, an event in U2ce, 55.6 m due north of UE2ce.
Date: March 3, 1982
Creator: Pawloski, G.A.
Partner: UNT Libraries Government Documents Department

Quantitative determination of minerals in Nevada Test Site samples by x-ray diffraction

Description: The external standard intensity ratio technique has been developed into a routine procedure for quantitatively determining mineralogic compositions of Nevada Test Site (NTS) samples by x-ray diffraction. This technique used ratios of x-ray intensity peaks from the same run which eliminates many possible errors. Constants have been determined for each of thirteen minerals commonly found in NTS samples - quartz, montmorillonite, illite, clinoptilolite, cristobalite, feldspars, calcite, dolomite, hornblende, kaolinite, muscovite, biotite, and amorphous glass. Ratios of the highest intensity peak of each mineral to be quantified in the sample and the highest intensity peak of quartz are used to calculate sample composition. The technique has been tested on samples with three to eleven components representative of geologic environments at NTS, and is accurate to 7.0 wt % of the total sample. The minimum amount of each of these minerals detectable by x-ray diffraction has also been determined. QUANTS is a computer code that calculates mineral contents and produces a report sheet. Constants for minerals in NTS samples other than those listed above can easily be determined, and added to QUANTS at any time.
Date: July 1, 1983
Creator: Pawloski, G.A.
Partner: UNT Libraries Government Documents Department

Evaluation of Cavity Collapse and Surface Crater Formation at the Norbo Underground Nuclear Test in U8c, Nevada Nuclear Security Site, and the Impact on Stability of the Ground Surface

Description: Lawrence Livermore National Laboratory (LLNL) Containment Program performed a review of nuclear test-related data for the Norbo underground nuclear test in U8c to assist in evaluating this legacy site as a test bed for application technologies for use in On-Site Inspections (OSI) under the Comprehensive Nuclear Test Ban Treaty. This request is similar to one made for the Salut site in U8c (Pawloski, 2012b). Review of the Norbo site is complicated because the test first exhibited subsurface collapse, which was not unusual, but it then collapsed to the surface over one year later, which was unusual. Of particular interest is the stability of the ground surface above the Norbo detonation point. Proposed methods for on-site verification include radiological signatures, artifacts from nuclear testing activities, and imaging to identify alteration to the subsurface hydrogeology due to the nuclear detonation. Aviva Sussman from the Los Alamos National Laboratory (LANL) has also proposed work at this site. Both proposals require physical access at or near the ground surface of specific underground nuclear test locations at the Nevada Nuclear Security Site (NNSS), formerly the Nevada Test Site (NTS), and focus on possible activities such as visual observation, multispectral measurements, and shallow and deep geophysical surveys.
Date: June 18, 2012
Creator: Pawloski, G. A.
Partner: UNT Libraries Government Documents Department

Evaluation of Cavity Collapse and Surface Crater Formation at the Salut Underground Nuclear Test in U20ak, Nevada National Security Site, and the Impact of Stability of the Ground Surface

Description: At the request of Jerry Sweeney, the LLNL Containment Program performed a review of nuclear test-related data for the Salut underground nuclear test in U20ak to assist in evaluating this legacy site as a test bed for application technologies for use in On-Site Inspections (OSI) under the Comprehensive Nuclear Test Ban Treaty. Review of the Salut site is complicated because the test experienced a subsurface, rather than surface, collapse. Of particular interest is the stability of the ground surface above the Salut detonation point. Proposed methods for on-site verification include radiological signatures, artifacts from nuclear testing activities, and imaging to identify alteration to the subsurface hydrogeologogy due to the nuclear detonation. Sweeney's proposal requires physical access at or near the ground surface of specific underground nuclear test locations at the Nevada Nuclear Test Site (NNSS, formerly the Nevada Test Site), and focuses on possible activities such as visual observation, multispectral measurements, and shallow, and deep geophysical surveys.
Date: April 25, 2012
Creator: Pawloski, G. A.
Partner: UNT Libraries Government Documents Department

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Tests - 2011

Description: This report evaluates collapse evolution for selected Lawrence Livermore National Laboratory (LLNL) underground nuclear tests at the Nevada National Security Site (NNSS, formerly called the Nevada Test Site). The work is being done at the request of National Security Technologies, LLC (NSTec) and supports the Department of Energy, National Nuclear Security Administration for the Nevada Site Office Borehole Management Program (BMP). The primary objective of this program is to close (plug) weapons program legacy boreholes that are deemed no longer useful. Safety decisions must be made before a crater area, or potential crater area, can be reentered for any work. Our statements on cavity collapse and crater formation are input into their safety decisions. The BMP is an on-going program to address hundreds of boreholes at the NTS. Each year NSTec establishes a list of holes to be addressed. They request the assistance of the Lawrence Livermore National Laboratory and Los Alamos National Laboratory Containment Programs to provide information related to the evolution of collapse history and make statements on completeness of collapse as relates to surface crater stability. These statements do not include the effects of erosion that may modify the collapse craters over time. They also do not address possible radiation dangers that may be present. Subject matter experts from the LLNL Containment Program who had been active in weapons testing activities performed these evaluations. Information used included drilling and hole construction, emplacement and stemming, timing and sequence of the selected test and nearby tests, geology, yield, depth of burial, collapse times, surface crater sizes, cavity and crater volume estimations, ground motion, and radiological release information. Both classified and unclassified data were reviewed. Various amounts of information are available for these tests, depending on their age and other associated activities. Lack of data can hamper evaluations and introduce ...
Date: February 28, 2011
Creator: Pawloski, G. A.
Partner: UNT Libraries Government Documents Department

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests - 2010

Description: This report evaluates collapse evolution for selected Lawrence Livermore National Laboratory (LLNL) underground nuclear tests at the Nevada National Security Site (NNSS, formerly called the Nevada Test Site). The work is being done at the request of Navarro-Interra LLC, and supports environmental restoration efforts by the Department of Energy, National Nuclear Security Administration for the Nevada Site Office. Safety decisions must be made before a surface crater area, or potential surface crater area, can be reentered for any work. Our statements on cavity collapse and surface crater formation are input into their safety decisions. These statements do not include the effects of erosion that may modify the surface collapse craters over time. They also do not address possible radiation dangers that may be present. Subject matter experts from the LLNL Containment Program who had been active in weapons testing activities performed these evaluations. Information used included drilling and hole construction, emplacement and stemming, timing and sequence of the selected test and nearby tests, geology, yield, depth of burial, collapse times, surface crater sizes, cavity and crater volume estimations, and ground motion. Both classified and unclassified data were reviewed. Various amounts of information are available for these tests, depending on their age and other associated activities. Lack of data can hamper evaluations and introduce uncertainty. We make no attempt to quantify this uncertainty.
Date: January 3, 2011
Creator: Pawloski, G. A.
Partner: UNT Libraries Government Documents Department

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests - 2011, Part 2

Description: This report evaluates collapse evolution for selected Lawrence Livermore National Laboratory (LLNL) underground nuclear tests at the Nevada National Security Site (NNSS, formerly called the Nevada Test Site). The work is being done to support several different programs that desire access to the ground surface above expended underground nuclear tests. The programs include: the Borehole Management Program, the Environmental Restoration Program, and the National Center for Nuclear Security Gas-Migration Experiment. Safety decisions must be made before a crater area, or potential crater area, can be reentered for any work. Evaluation of cavity collapse and crater formation is input into the safety decisions. Subject matter experts from the LLNL Containment Program who participated in weapons testing activities perform these evaluations. Information used included drilling and hole construction, emplacement and stemming, timing and sequence of the selected test and nearby tests, geology, yield, depth of burial, collapse times, surface crater sizes, cavity and crater volume estimations, ground motion, and radiological release information. Both classified and unclassified data were reviewed. The evaluations do not include the effects of erosion that may modify the collapse craters over time. They also do not address possible radiation dangers that may be present. Various amounts of information are available for these tests, depending on their age and other associated activities. Lack of data can hamper evaluations and introduce uncertainty. We make no attempt to quantify this uncertainty. Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests - 2011 was published on March 2, 2011. This report, considered Part 2 of work undertaken in calendar year 2011, compiles evaluations requested after the March report. The following unclassified summary statements describe collapse evolution and crater stability in response to a recent request to review 6 LLNL test locations in Yucca Flat, ...
Date: January 30, 2012
Creator: Pawloski, G. A.
Partner: UNT Libraries Government Documents Department

Development of Phenomenological Models of Underground Nuclear Tests on Pahute Mesa, Nevada Test Site - BENHAM and TYBO

Description: Although it is well accepted that underground nuclear explosions modify the in situ geologic media around the explosion point, the details of these changes are neither well understood nor well documented. As part of the engineering and containment process before a nuclear test, the physical environment is characterized to some extent to predict how the explosion will interact with the in situ media. However, a more detailed characterization of the physical environment surrounding an expended site is needed to successfully model radionuclide transport in the groundwater away from the detonation point. It is important to understand how the media have been altered and where the radionuclides are deposited. Once understood, this information on modified geologic media can be incorporated into a phenomenological model that is suitable for input to computer simulations of groundwater flow and radionuclide transport. The primary goals of this study are to (1) identify the modification of the media at a pertinent scale, and (2) provide this information to researchers modeling radionuclide transport in groundwater for the US Department of Energy (DOE) Nevada Operations Office Underground Test Area (UGTA) Project. Results from this study are most applicable at near-field scale (a model domain of about 500 m) and intermediate-field scale (a model domain of about 5 km) for which detailed information can be maximized as it is incorporated in the modeling grids. UGTA collected data on radionuclides in groundwater during recent drilling at the ER-20-5 site, which is near BENHAM and TYBO on Pahute Mesa at the Nevada Test Site (NTS). Computer simulations are being performed to better understand radionuclide transport. The objectives of this modeling effort include: evaluating site-specific information from the BENHAM and TYBO tests on Pahute Mesa; augmenting the above data set with generalized containment data; and developing a phenomenological model suitable for input ...
Date: September 21, 1999
Creator: Pawloski, G. A.
Partner: UNT Libraries Government Documents Department

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests - 2006

Description: This report describes evaluation of collapse evolution for selected LLNL underground nuclear tests at the Nevada Test Site (NTS). The work is being done at the request of Bechtel Nevada and supports the Department of Energy National Nuclear Security Association Nevada Site Office Borehole Management Program (BMP). The primary objective of this program is to close (plug) weapons program legacy boreholes that are deemed no longer useful. Safety decisions must be made before a crater area, or potential crater area, can be reentered for any work. Our statements on cavity collapse and crater formation are input into their safety decisions. The BMP is an on-going program to address hundreds of boreholes at the NTS. Each year Bechtel Nevada establishes a list of holes to be addressed. They request the assistance of the Lawrence Livermore National Laboratory and Los Alamos National Laboratory Containment Programs to provide information related to the evolution of collapse history and make statements on completeness of collapse as relates to surface crater stability. These statements do not include the effects of erosion that may modify the collapse craters over time. They also do not address possible radiation dangers that may be present. Subject matter experts from the LLNL Containment Program and the Chemistry Biology and Nuclear Sciences Division who had been active in weapons testing activities performed these evaluations. Information used included drilling and hole construction, emplacement and stemming, timing and sequence of the selected test and nearby tests, geology, yield, depth of burial, collapse times, surface crater sizes, cavity and crater volume estimations, and ground motion. Both classified and unclassified data were reviewed. Various amounts of information are available for these tests, depending on their age and other associated activities. Lack of data can hamper evaluations and introduce uncertainty. We make no attempt to quantify this ...
Date: March 16, 2006
Creator: Pawloski, G. A. & Raschke, K.
Partner: UNT Libraries Government Documents Department

The Underground Test Area Project of the Nevada Test Site: Building Confidence in Groundwater Flow and Transport Models at Pahute Mesa Through Focused Characterization Studies

Description: Pahute Mesa at the Nevada Test Site contains about 8.0E+07 curies of radioactivity caused by underground nuclear testing. The Underground Test Area Subproject has entered Phase II of data acquisition, analysis, and modeling to determine the risk to receptors from radioactivity in the groundwater, establish a groundwater monitoring network, and provide regulatory closure. Evaluation of radionuclide contamination at Pahute Mesa is particularly difficult due to the complex stratigraphy and structure caused by multiple calderas in the Southwestern Nevada Volcanic Field and overprinting of Basin and Range faulting. Included in overall Phase II goals is the need to reduce the uncertainty and improve confidence in modeling results. New characterization efforts are underway, and results from the first year of a three-year well drilling plan are presented.
Date: December 29, 2009
Creator: Pawloski, G A; Wurtz, J & Drellack, S L
Partner: UNT Libraries Government Documents Department

Turning Points in Containment of Lawrence Livermore National Laboratory Underground Nuclear Tests

Description: Sometime in 1987 Billy Hudson, a long-time LLNL Containment Scientist and the Task Leader for Containment Diagnostics, put together a presentation entitled ''Turning Points in Containment''. This presentation identifies challenges, lessons learned, and changes made in containment practice over a 20-year period, from 1967-1987. Besides providing a significant historical summary, the presentation is valuable as we maintain a position of readiness 14 years after the last underground nuclear detonation. It is particularly valuable to personnel who are new to the program and have no first-hand experience in implementing underground nuclear test containment for actual tests. We now view this material as a unique containment summary with timeless importance. We envision this report to be particularly useful to new Containment Program members and anyone interested in the history of underground nuclear test containment practices. We believe that the Barnwell test, detonated in 1989, would have been added to this summary if Billy Hudson had the opportunity to update the presentation. We have chosen to add a few slides to the end of the original presentation to describe the issues and lessons learned from Barnwell.
Date: November 21, 2006
Creator: Hudson, B C; Rambo, J T; Pawloski, G A & Burkhard, N R
Partner: UNT Libraries Government Documents Department

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests - 2007

Description: This report describes evaluation of collapse evolution for selected LLNL underground nuclear tests at the Nevada Test Site (NTS). The work is being done at the request of NSTec and supports the Department of Energy National Nuclear Security Association Nevada Site Office Borehole Management Program (BMP). The primary objective of this program is to close (plug) weapons program legacy boreholes that are deemed no longer useful. Safety decisions must be made before a crater area, or potential crater area, can be reentered for any work. Our statements on cavity collapse and crater formation are input into their safety decisions. The BMP is an on-going program to address hundreds of boreholes at the NTS. Each year NSTec establishes a list of holes to be addressed. They request the assistance of the Lawrence Livermore National Laboratory and Los Alamos National Laboratory Containment Programs to provide information related to the evolution of collapse history and make statements on completeness of collapse as relates to surface crater stability. These statements do not include the effects of erosion that may modify the collapse craters over time. They also do not address possible radiation dangers that may be present. Subject matter experts from the LLNL Containment Program and the Chemical Sciences Division who had been active in weapons testing activities performed these evaluations. Information used included drilling and hole construction, emplacement and stemming, timing and sequence of the selected test and nearby tests, geology, yield, depth of burial, collapse times, surface crater sizes, cavity and crater volume estimations, and ground motion. Both classified and unclassified data were reviewed. Various amounts of information are available for these tests, depending on their age and other associated activities. Lack of data can hamper evaluations and introduce uncertainty. We make no attempt to quantify this uncertainty. The following unclassified summary ...
Date: April 26, 2007
Creator: Roberts, S K; Pawloski, G A & Raschke, K
Partner: UNT Libraries Government Documents Department

A preliminary guidebook for identifying stratigraphic contacts at the Nevada Test Site

Description: Lithologic variation, regional depositional trends, and the lack of written guidelines have resulted in inconsistencies in the recognition of stratigraphic contacts in drill holes at the Nevada Test Site (NTS). Stratigraphic identification, based on mineralogy of discrete samples, can be augmented by geophysical logs and downhole movies to more accurately and consistently locate contacts between units. Criteria are established for locating the base of the Pahute Mesa ash-flow tuff, the top of the Ammonia Tanks ash-flow tuff, the top of the Ammonia Tanks bedded tuff, and the top and the base of the Rainier Mesa Tuff.
Date: January 1, 1992
Creator: Pawloski, G.A.; McKague, H.L.; Wagoner, J.L. & McKinnis, W.B.
Partner: UNT Libraries Government Documents Department

Continental scientific drilling program data base: 1982

Description: The Continental Scientific Drilling Program (CSDP) data base maintained at Lawrence Livermore National Laboratory is funded by the Office of Basic Energy Sciences of the Department of Energy. It is a central repository of information concerning approximately 1800 government funded and scientifically interesting drill holes in the United States. This data base can help reduce drilling costs and maximize scientific value of drilling efforts of government agencies and industry. The services of the CSDP data base are free of charge and available to all.
Date: May 18, 1982
Creator: Pawloski, G.A.; Howard, N.; Hage, G.; Higuera; M.L. & Richardson, W.
Partner: UNT Libraries Government Documents Department

Evaluation of the Transient Hydrologic Source Term for the Cambric Underground Nuclear Test at Frenchman Flat, Nevada test Site

Description: The objective of Phase II HST work is to develop a better understanding of the evolution of the HST for 1,000 years at the CAMBRIC underground nuclear test site in Frenchman Flat at the NTS. This work provides a better understanding of activities as they actually occurred, incorporates improvements based on recent data acquisition, and provides a basis to use the CAMBRIC site for model validation and monitoring activities as required by the UGTA Project. CAMBRIC was the only test in Frenchman Flat detonated under the water table and best represents a fully saturated environment. These simulations are part of a broad Phase II Frenchman Flat Corrective Action Unit (CAU) flow and transport modeling effort being conducted by the Department of Energy (DOE) Underground Test Area (UGTA) Project. HST simulations provide, either directly or indirectly, the source term used in the CAU model to calculate a contaminant boundary. Work described in this report augments Phase I HST calculations at CAMBRIC conducted by Tompson et al. (1999) and Pawloski et al. (2001). Phase II HST calculations have been organized to calculate source terms under two scenarios: (1) A representation of the transient flow and radionuclide release behavior at the CAMBRIC site that is more specific than Tompson et al. (1999). This model reflects the influence of the background hydraulic gradient, residual test heat, pumping experiment, and ditch recharge, and takes into account improved data sources and modeling approaches developed since the previous efforts. Collectively, this approach will be referred to as the transient CAMBRIC source term. This report describes the development of the transient CAMBRIC HST. (2) A generic release model made under steady-state flow conditions, in the absence of any transient effects, at the same site with the same radiologic source term. This model is for use in the development ...
Date: December 12, 2006
Creator: Carle, S F; Maxwell, R M; Pawloski, G A; Shumaker, D E; Tompson, A B & Zavarin, M
Partner: UNT Libraries Government Documents Department

Evaluation of the Non-Transient Hydrologic Source Term from the CAMBRIC Underground Nuclear Test in Frenchman Flat, Nevada Test Site

Description: Hydrologic Source Term (HST) calculations completed in 1998 at the CAMBRIC underground nuclear test site were LLNL's first attempt to simulate a hydrologic source term at the NTS by linking groundwater flow and transport modeling with geochemical modeling (Tompson et al., 1999). Significant effort was applied to develop a framework that modeled in detail the flow regime and captured all appropriate chemical processes that occurred over time. However, portions of the calculations were simplified because of data limitations and a perceived need for generalization of the results. For example: (1) Transient effects arising from a 16 years of pumping at the site for a radionuclide migration study were not incorporated. (2) Radionuclide fluxes across the water table, as derived from infiltration from a ditch to which pumping effluent was discharged, were not addressed. (3) Hydrothermal effects arising from residual heat of the test were not considered. (4) Background data on the ambient groundwater flow direction were uncertain and not represented. (5) Unclassified information on the Radiologic Source Term (RST) inventory, as tabulated recently by Bowen et al. (2001), was unavailable; instead, only a limited set of derived data were available (see Tompson et al., 1999). (6) Only a small number of radionuclides and geochemical reactions were incorporated in the work. (7) Data and interpretation of the RNM-2S multiple well aquifer test (MWAT) were not available. As a result, the current Transient CAMBRIC Hydrologic Source Term project was initiated as part of a broader Phase 2 Frenchman Flat CAU flow and transport modeling effort. The source term will be calculated under two scenarios: (1) A more specific representation of the transient flow and radionuclide release behavior at the site, reflecting the influence of the background hydraulic gradient, residual test heat, pumping experiment, and ditch recharge, and taking into account improved data ...
Date: August 5, 2005
Creator: Tompson, A B; Maxwell, R M; Carle, S F; Zavarin, M; Pawloski, G A & Shumaker, D E
Partner: UNT Libraries Government Documents Department

Simulating Effects of Non-Isothermal Flow on Reactive Transport of Radionuclides Originating from an Underground Nuclear Test

Description: Temperature can significantly affect radionuclide transport behavior. In simulation of radionuclide transport originating from an underground nuclear test, temperature effects from residual test heat include non-isothermal groundwater flow behavior (e.g. convection cells), increased dissolution rates of melt glass containing refractory radionuclides, changes in water chemistry, and, in turn, changes in radionuclide sorption behavior. The low-yield (0.75 kiloton) Cambric underground nuclear test situated in alluvium below the water table offers unique perspectives on radionuclide transport in groundwater. The Cambric test was followed by extensive post-test characterization of the radionuclide source term and a 16-year pumping-induced radionuclide migration experiment that captured more mobile radionuclides in groundwater. Discharge of pumped groundwater caused inadvertent recirculation of radionuclides through a 220-m thick vadose zone to the water table and below, including partial re-capture in the pumping well. Non-isothermal flow simulations indicate test-related heat persists at Cambric for about 10 years and induces limited thermal convection of groundwater. The test heat has relatively little impact on mobilizing radionuclides compared to subsequent pumping effects. However, our reactive transport models indicate test-related heat can raise melt glass dissolution rates up to 10{sup 4} faster than at ambient temperatures depending on pH and species activities. Non-isothermal flow simulations indicate that these elevated glass dissolution rates largely decrease within 1 year. Thermally-induced increases in fluid velocity may also significantly increase rates of melt glass dissolution by changing the fluid chemistry in contact with the dissolving glass.
Date: March 6, 2006
Creator: Carle, S F; Zavarin, M; Shumaker, D E; Tompson, A B; Maxwell, R M & Pawloski, G A
Partner: UNT Libraries Government Documents Department

Thermally Induced Groundwater Flow Resulting from an Underground Nuclear Test

Description: The authors examine the transient residual thermal signal resulting from an underground nuclear test (buried below the water table) and its potential to affect local groundwater flow and radionuclide migration in a saturated, fractured, volcanic aquifer system. Thermal profiles measured in a drillback hole between 154 days and 6.5 years after the test have been used to calibrate a non-isothermal model of fluid flow. In this process, they have estimated the magnitude and relative changes in permeability, porosity and fracture density between different portions of the disturbed and undisturbed geologic medium surrounding the test location. The relative impacts of buoyancy forces (arising from the thermal residual of the test and the background geothermal gradient) and horizontal pressure gradients on the post-test flow system are better understood. A transient particle/streamline model of contaminant transport is used to visualize streamlines and streaklines of the flow field and to examine the migration of non-reactive radionuclides. Sensitivity analyses are performed to understand the effects of local and sub-regional geologic features, and the effects of fractured zones on the movement of groundwater and thermal energy. Conclusions regarding the overall effect of the thermal regime on the residence times and fluxes of radionuclides out of the system are drawn, and implications for more complicated, reactive contaminant transport are discussed.
Date: December 16, 2000
Creator: Maxwell, R.M.; Tompson, A.F.B.; Rambo, J.T.; Carle, S.F. & Pawloski, G.A.
Partner: UNT Libraries Government Documents Department

Evaluation of the hydrologic source term from underground nuclear tests in Frenchman Flat at the Nevada Test Site: The Cambric test

Description: The objectives of this project are to develop and apply a modeling frame- work to quantitatively evaluate the nature and extent of radionuclide migration within the immediate, near field environment about an underground nuclear test. Specifically, it will involve evaluation of ² The speciation and abundance of radionuclides that are introduced into groundwater as aqueous species or colloids, and ² The rate and extent of radionuclide movement, dilution, and reaction in groundwater surrounding the working point of a test. To be clear, interest will only be focused on processes that have occurred well after the nuclear test, as opposed to the more dynamic processes that take place during or immediately after detonation. The meaning of "near field" in this case will loosely refer to a volume of diameter 4-8 R<sub>c</sub>, centered on the working point and chimney of the test, where Rc is the radius of the blast cavity. For a given nuclear test, this information will collectively comprise the test's "hydrologic source term". This work relies on and is being supported by existing data, analyses, and interpretations that have been made at the Nevada Test Site (NTS) during the American nuclear test program and previous and ongoing studies related to radionuclide migration in the subsurface (Kersting, 1996).
Date: March 23, 1999
Creator: Bourcier, W L; Bruton, C J; Carle, S F; Kersting, A B; Pawloski, G A; Rard, J A et al.
Partner: UNT Libraries Government Documents Department

Simulation of Radionuclide Migration in Groundwater away from an Underground Nuclear Test

Description: Reactive transport simulations are being used to evaluate the nature and extent of radionuclide contamination within alluvium surrounding an 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 can proceed.
Date: December 13, 1999
Creator: Bruton, C.J.; Bourcier, W.L.; Shumaker, D.E.; Kersting, A.B.; Smith, D.K.; Carle, S.F. et al.
Partner: UNT Libraries Government Documents Department