Download or read book Evaluation of the Radiochemistry of Near Field Water Samples at the Nevada Test Site Applied to the Definition of a Hydrologic Source Term written by and published by . This book was released on 2002 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effective management of available groundwater resources and strategies for remediation of water impacted by past nuclear testing practices depend on knowledge about the migration of radionuclides in groundwater away from the sites of the explosions. A primary concern is to assess the relative mobilities of the different radionuclide species found near sites of underground nuclear tests and to determine the concentration, extent, and speed of this movement. Ultimately the long term transport behavior of radionuclides with half-lives long enough that they will persist for decades, their interaction with groundwater, and the resulting flux of these contaminants is of paramount importance. As part of a comprehensive approach to these assessments, more than three decades of site-specific sites studies have been undertaken at the Nevada Test Site (NTS) which have focused on the means responsible for the observed or suspected movement of radionuclides away from underground nuclear tests (RNM, 1983). More recently regional and local models of groundwater flow and radionuclide transport have been developed as part of a federal and state of Nevada program to assess the long-term effects of underground nuclear testing on human health and environment (e.g., U.S. DOE/NV, 1997a; Tompson et al., 1999; Pawloski et al., 2001). Necessary to these efforts is a reliable measure of the hydrologic source term which is defined as those radionuclides dissolved in or otherwise transported by groundwater (Smith et al., 1995). Measurement of radionuclides in waters sampled near the sites of underground nuclear test provides arguably the best opportunity to bound the hydrologic source term. This empirical approach was recognized early and concentration data has been collected annually since mid-1970's. Initially three sites were studied at the NTS; over the years the program has been expanded to include more than fifteen study locations. As part of various field programs, Lawrence Livermore National Laboratory and Los Alamos National Laboratory have annually returned water samples from wells in near-field locations at the NTS for radiochemical analyses. This report makes the distinction between samples taken in the near-field and the far field. The near-field includes the area extending radially (almost equal to)300 meters from surface ground zero (the firing point of an underground nuclear test projected upwards on ground surface). Over the years this sampling program has also been refereed to as the ''hot-well monitoring program'' because these water samples contained concentrations of tritium above natural background (tritium concentrations in southern Nevada precipitation are 0.5 to 2.0 Bq/L, Farmer et al., 1998). A majority of the hot wells contain tritium in excess of the 741 Bq/L (20,000 pCi/L) drinking water standard (Smith et al., 1996a; Smith et al., 1997). The sites which comprise our current hot well sampling network are plotted on a map of the NTS in Figure 1.
Download or read book Autograph Letter Signed from E P Vining Omaha to Rev Karl Kurtz Johnstown Pennsylvania written by and published by . This book was released on 1881 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vining speaks of translating his work The mystery of Hamlet into German.
Download or read book Challenges in Defining a Radiologic and Hydrologic Source Term for Underground Nuclear Test Centers Nevada Test Site Nye County Nevada written by and published by . This book was released on 1995 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The compilation of a radionuclide inventory for long-lived radioactive contaminants residual from nuclear testing provides a partial measure of the radiologic source term at the Nevada Test Site. The radiologic source term also includes potentially mobile short-lived radionuclides excluded from the inventory. The radiologic source term for tritium is known with accuracy and is equivalent to the hydrologic source term within the saturated zone. Definition of the total hydrologic source term for fission and activation products that have high activities for decades following underground testing involves knowledge and assumptions which are presently unavailable. Systematic investigation of the behavior of fission products, activation products and actinides under saturated or Partially saturated conditions is imperative to define a representative total hydrologic source term. This is particularly important given the heterogeneous distribution of radionuclides within testing centers. Data quality objectives which emphasize a combination of measurements and credible estimates of the hydrologic source term are a priority for near-field investigations at the Nevada Test Site.
Download or read book Evaluation of the Hydrologic Source Term from Underground Nuclear Tests on Pahute Mesa at the Nevada Test Site written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this report are to develop, summarize, and interpret a series of detailed unclassified simulations that forecast the nature and extent of radionuclide release and near-field migration in groundwater away from the CHESHIRE underground nuclear test at Pahute Mesa at the NTS over 1000 yrs. Collectively, these results are called the CHESHIRE Hydrologic Source Term (HST). The CHESHIRE underground nuclear test was one of 76 underground nuclear tests that were fired below or within 100 m of the water table between 1965 and 1992 in Areas 19 and 20 of the NTS. These areas now comprise the Pahute Mesa Corrective Action Unit (CAU) for which a separate subregional scale flow and transport model is being developed by the UGTA Project to forecast the larger-scale migration of radionuclides from underground tests on Pahute Mesa. The current simulations are being developed, on one hand, to more fully understand the complex coupled processes involved in radionuclide migration, with a specific focus on the CHESHIRE test. While remaining unclassified, they are as site specific as possible and involve a level of modeling detail that is commensurate with the most fundamental processes, conservative assumptions, and representative data sets available. However, the simulation results are also being developed so that they may be simplified and interpreted for use as a source term boundary condition at the CHESHIRE location in the Pahute Mesa CAU model. In addition, the processes of simplification and interpretation will provide generalized insight as to how the source term behavior at other tests may be considered or otherwise represented in the Pahute Mesa CAU model.
Download or read book Unclassified Source Term and Radionuclide Data for Corrective Action Unit 98 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Frenchman Flat is one of several areas of the Nevada Test Site (NTS) used for underground nuclear testing (Figure 1-1). These nuclear tests resulted in groundwater contamination in the vicinity of the underground test areas. As a result, the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office (NNSA/NSO) is currently conducting a corrective action investigation (CAI) of the Frenchman Flat underground test areas. Since 1996, the Nevada Division of Environmental Protection (NDEP) has regulated NNSA/NSO corrective actions through the ''Federal Facility Agreement and Consent Order'' ([FFACO], 1996). Appendix VI of the FFACO agreement, ''Corrective Action Strategy'', was revised on December 7, 2000, and describes the processes that will be used to complete corrective actions, including those in the Underground Test Area (UGTA) Project. The individual locations covered by the agreement are known as corrective action sites (CASs), which are grouped into corrective action units (CAUs). The UGTA CASs are grouped geographically into five CAUs: Frenchman Flat, Central Pahute Mesa, Western Pahute Mesa, Yucca Flat/Climax Mine, and Rainier Mesa/Shoshone Mountain (Figure 1-1). These CAUs have distinctly different contaminant source, geologic, and hydrogeologic characteristics related to their location (FFACO, 1996). The Frenchman Flat CAU consists of 10 CASs located in the northern part of Area 5 and the southern part of Area 11 (Figure 1-1). This report documents the evaluation of the information and data available on the unclassified source term and radionuclide contamination for Frenchman Flat, CAU 98. The methodology used to estimate hydrologic source terms (HSTs) for the Frenchman Flat CAU is also documented. The HST of an underground nuclear test is the portion of the total inventory of radionuclides that is released over time into the groundwater following the test. The total residual inventory of radionuclides associated with one or more tests is known as the radiologic source term (RST). The RST is comprised of radionuclides in water, glass, or other phases or mineralogic forms. This evaluation was conducted in support of the development of a CAU contaminant transport model for the Frenchman Flat CAU.
Download or read book State of the Hydrologic Source Term written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Underground Test Area (UGTA) Operable Unit was defined by the U.S. Department of energy, Nevada operations Office to characterize and potentially remediate groundwaters impacted by nuclear testing at the Nevada Test Site (NTS). Between 1955 and 1992, 828 nuclear devices were detonated underground at the NTS (DOE), 1994. Approximately one third of the nuclear tests were detonated at or below the standing water table and the remainder were located above the water table in the vadose zone. As a result, the distribution of radionuclides in the subsurface and, in particular, the availability of radionuclides for transport away from individual test cavities are major concerns at the NTS. The approach taken is to carry out field-based studies of both groundwaters and host rocks within the near-field in order to develop a detailed understanding of the present-day concentration and spatial distribution of constituent radionuclides. Understanding the current distribution of contamination within the near-field and the conditions under and processes by which the radionuclides were transported make it possible to predict future transport behavior. The results of these studies will be integrated with archival research, experiments and geochemical modeling for complete characterization.
Download or read book Laboratory and Field Studies Related to Radionuclide Migration at the Nevada Test Site written by and published by . This book was released on 1999 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report, we describe the work done in FY 1998 at Los Alamos National Laboratory as part of the Hydrologic Resources Management Program (HRMA) funded by the Nevada Operations Office of the US Department of Energy (DOE/NV). The major part of our research effort was to measure radionuclides present in water or soil samples collected from near nuclear tests. We report our measurements for materials collected in both saturated and unsaturated horizons adjacent to nuclear test cavities or collapse chimneys and from within several cavities. Soil samples collected from above the cavities formed by the Halfbeak, Jerboa, and Bobac tests contained no radioactivity, although a test similar to Bobac in the same area had been contaminated with 137Cs. Water samples from near the Shoal test contained no measurable radionuclides, whereas those from near Faultless and Aleman had concentrations similar to previous measurements. Water from the Tybo-Benham site was similar to earlier collections at that site; this year, we added 241Am to the list of radionuclides measured at this location. Two Bennett pumps in tandem were used to extract water from the piezometer tube in the cavity of the Dalhart event. This extraction is a significant achievement in that it opens the possibility of purging similar tubes at other locations on the NTS. The Cheshire post shot hole was reconfigured and pumped from two horizons for the first time since mid-1980. We are especially interested in examining water from the level of the working point to determine the hydrologic source term in a cavity filled with groundwater for over 20 years. We devoted much time this year to examining the colloid content of NTS groundwater. After developing protocols for collecting, handling, and storing groundwater samples without altering their colloid content, we analyzed water from the Tybo-Benham and from the Cheshire sites. Whereas the colloid concentration did not vary much with depth at Tybo-Benham, there were 20 times more colloids in groundwater from the Cheshire cavity than were found a few hundred meters higher. Electron micrographs show the wide variety of colloid sizes and shapes present in NTS groundwater. Our experiences with filtration of groundwater samples illustrate the difficulties of colloid size characterization using this methodology. Our report ends with a description of our consultative and educational activities and a list of recent publications.
Download or read book Evaluation of the Non Transient Hydrologic Source Term from the CAMBRIC Underground Nuclear Test in Frenchman Flat Nevada Test Site written by R. M. Maxwell and published by . This book was released on 2005 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 sources and modeling approaches acquired or developed since the previous work (as in Pawloski et al., 2001, at the CHESHIRE site). This will be referred to as the transient CAMBRIC source term. (2) A generic release model made under steady-state flow conditions, in the absence of any transient effect, at the same site with the same RST for use in the development of simple release models at the other nine underground test sites in the Frenchman Flat CAU. This will be referred to as the steady state (non-transient) source term. The purpose of this report is to summarize the results of our steady state source term simulations. Additional details pertaining to these results, the transient model results, and the overall strategy, rationale, and assumptions used in the models will be documented in a separate report.
Download or read book RADIOACTIVITY IN WATER CENTRAL NEVADA TEST AREA written by and published by . This book was released on 1971 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Regional Groundwater Flow and Tritium Transport Modeling and Risk Assessment of the Underground Test Area Nevada Test Site Nevada written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The groundwater flow system of the Nevada Test Site and surrounding region was evaluated to estimate the highest potential current and near-term risk to the public and the environment from groundwater contamination downgradient of the underground nuclear testing areas. The highest, or greatest, potential risk is estimated by assuming that several unusually rapid transport pathways as well as public and environmental exposures all occur simultaneously. These conservative assumptions may cause risks to be significantly overestimated. However, such a deliberate, conservative approach ensures that public health and environmental risks are not underestimated and allows prioritization of future work to minimize potential risks. Historical underground nuclear testing activities, particularly detonations near or below the water table, have contaminated groundwater near testing locations with radioactive and nonradioactive constituents. Tritium was selected as the contaminant of primary concern for this phase of the project because it is abundant, highly mobile, and represents the most significant contributor to the potential radiation dose to humans for the short term. It was also assumed that the predicted risk to human health and the environment from tritium exposure would reasonably represent the risk from other, less mobile radionuclides within the same time frame. Other contaminants will be investigated at a later date. Existing and newly collected hydrogeologic data were compiled for a large area of southern Nevada and California, encompassing the Nevada Test Site regional groundwater flow system. These data were used to develop numerical groundwater flow and tritium transport models for use in the prediction of tritium concentrations at hypothetical human and ecological receptor locations for a 200-year time frame. A numerical, steady-state regional groundwater flow model was developed to serve as the basis for the prediction of the movement of tritium from the underground testing areas on a regional scale. The groundwater flow model was used in conjunction with a particle-tracking code to define the pathlines followed by groundwater particles originating from 415 points associated with 253 nuclear test locations. Three of the most rapid pathlines were selected for transport simulations. These pathlines are associated with three nuclear test locations, each representing one of the three largest testing areas. These testing locations are: BOURBON on Yucca Flat, HOUSTON on Central Pahute Mesa, and TYBO on Western Pahute Mesa. One-dimensional stochastic tritium transport simulations were performed for the three pathlines using the Monte Carlo method with Latin hypercube sampling. For the BOURBON and TYBO pathlines, sources of tritium from other tests located along the same pathline were included in the simulations. Sensitivity analyses were also performed on the transport model to evaluate the uncertainties associated with the geologic model, the rates of groundwater flow, the tritium source, and the transport parameters. Tritium concentration predictions were found to be mostly sensitive to the regional geology in controlling the horizontal and vertical position of transport pathways. The simulated concentrations are also sensitive to matrix diffusion, an important mechanism governing the migration of tritium in fractured carbonate and volcanic rocks. Source term concentration uncertainty is most important near the test locations and decreases in importance as the travel distance increases. The uncertainty on groundwater flow rates is as important as that on matrix diffusion at downgradient locations. The risk assessment was performed to provide conservative and bounding estimates of the potential risks to human health and the environment from tritium in groundwater. Risk models were designed by coupling scenario-specific tritium intake with tritium dose models and cancer and genetic risk estimates using the Monte Carlo method. Estimated radiation doses received by individuals from chronic exposure to tritium, and the corresponding human health risks at hypothetical point-of-use locations along each of the pathlines were calculated for six potential land-use scenarios. Conservative land-use scenarios were postulated to ensure that the calculated exposures would bound any realistic dose received by individuals. Based on the human-health risk estimates, tritium exposures associated with the HOUSTON and BOURBON pathlines do not present a human health hazard off the Nevada Test Site in the present, the near term, or in the future. However, the estimates show that the TYBO pathline has the greatest potential for off-site release with a projected groundwater discharge at Oasis Valley. Using the most conservative scenario for tritium exposure demonstrates that dose could exceed the 100-mrem/yr limit at locations along the TYBO pathline.
Download or read book Radioactivity in the Hydrologic Environment Project Rulison Final Pre shot Report U written by William E. Nork and published by . This book was released on 1969 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unclassified Source Term and Radionuclide Data for Corrective Action Unit 97 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents the evaluation of the information and data available on the unclassified source term and radionuclide contamination for CAU 97: Yucca Flat/Climax Mine. The total residual inventory of radionuclides associated with one or more tests is known as the radiologic source term (RST). The RST is comprised of radionuclides in water, glass, or other phases or mineralogic forms. The hydrologic source term (HST) of an underground nuclear test is the portion of the total RST that is released into the groundwater over time following the test. In this report, the HST represents radionuclide release some time after the explosion and does not include the rapidly evolving mechanical, thermal, and chemical processes during the explosion. The CAU 97: Yucca Flat/Climax Mine has many more detonations and a wider variety of settings to consider compared to other CAUs. For instance, the source term analysis and evaluation performed for CAUs 101 and 102: Central and Western Pahute Mesa and CAU 98: Frenchman Flat did not consider vadose zone attenuation because many detonations were located near or below the water table. However, the large number of Yucca Flat/Climax Mine tests and the location of many tests above the water table warrant a more robust analysis of the unsaturated zone.
Download or read book Ground Water in the Oak Spring Formation and Hydrologic Effects of Underground Nuclear Explosions at the Nevada Test Site written by Alfred Clebsch and published by . This book was released on 1960 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The LLNL Nevada Test Side Underground Radionuclide Source term Inventory written by and published by . This book was released on 1995 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The potential for the contamination of ground water beneath the Nevada Test Site (NTS) by nuclear testing has long been recognized. The United States has conducted underground nuclear weapons testing at NTS since 1957, and a considerable amount of radioactive material has been deposited in the subsurface by this work. As a part of the U.S. Department of Energy Nevada Operations Office's Underground Test Area Operable Unit (UGTA OP), the Lawrence Livermore National Laboratory (LLNL) has compiled an inventory of radionuclides produced by underground LLNL weapons tests from 1957 through 1992. It is well known that some groundwater at NTS has been contaminated by radionuclides from weapons testing. Nearly one-third of the nuclear tests were conducted near or beneath the pre-test static water level (SWL). An important responsibility of the UGTA OP is to assess the migration potential of contaminants beneath the NTS and surrounding lands. Except for tritium (3H), which is capable of migration with water as molecular HTO, the ability of radionuclides to migrate significant distances from their source is presently thought to be very low. However, before this potential for migration can be fully assessed, the quantity of existing contaminants must be carefully estimated. The inventory of the radionuclide source term provides an upper limit on the availability of radionuclides for migration. However, an accurate assessment of risk to the public depends on more than an inventory of radionuclides remaining from underground testing. An estimate of the hydrologic source term consisting of radionuclides dissolved in or transported by ground water must compliment the radionuclide source term.
Download or read book Field Investigation at the Faultless Site Central Nevada Test Area written by and published by . This book was released on 1992 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: An evaluation of groundwater monitoring at non-Nevada Test Site underground nuclear test sites raised questions about the potential for radionuclide migration from the Faultless event and how to best monitor for such migration. With its long standing interest in the Faultless area and background in Nevada hydrogeology, the Desert Research Institute conducted a field investigation in FY92 to address the following issues: The status of chimney infilling (which determines the potential for migration); the best level(s) from which to collect samples from the nearby monitoring wells, HTH-1 and HTH-2; the status of hydraulic heads in the monitoring well area following records of sustained elevated post-shot heads. The field investigation was conducted from July 27 to 31 and August 4 to 7, 1992. Temperature and electrical conductivity logging were performed in HTH-1, HTH-2, and UC-1-P-2SR. Water samples were collected from HTH-1 and HTH-2. Lawrence Livermore National Laboratory (LLNL) also collected samples during the July trip, including samples from UC-1-P-2SR. This report presents the data gathered during these field excursions and some preliminary conclusions. Full interpretation of the data in light of the issues listed above is planned for FY93.
Download or read book Unclassified Sources Term and Radionuclide Data for Corrective Action Unit 97 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents the evaluation of the information and data available on the unclassified source term and radionuclide contamination for CAU 97: Yucca Flat/Climax Mine. The total residual inventory of radionuclides associated with one or more tests is known as the radiologic source term (RST). The RST is comprised of radionuclides in water, glass, or other phases or mineralogic forms. The hydrologic source term (HST) of an underground nuclear test is the portion of the total RST that is released into the groundwater over time following the test. In this report, the HST represents radionuclide release some time after the explosion and does not include the rapidly evolving mechanical, thermal, and chemical processes during the explosion. The CAU 97: Yucca Flat/Climax Mine has many more detonations and a wider variety of settings to consider compared to other CAUs. For instance, the source term analysis and evaluation performed for CAUs 101 and 102: Central and Western Pahute Mesa and CAU 98: Frenchman Flat did not consider vadose zone attenuation because many detonations were located near or below the water table. However, the large number of Yucca Flat/Climax Mine tests and the location of many tests above the water table warrant a more robust analysis of the unsaturated zone. The purpose of this report is to develop and document conceptual models of the Yucca Flat/Climax Mine HST for use in implementing source terms for the Yucca Flat/Climax Mine models. This document presents future plans to incorporate the radionuclide attenuation mechanisms due to unsaturated/multiphase flow and transport within the Yucca Flat CAU scale modeling. The important processes that influence radionuclide migration for the unsaturated and saturated tests in alluvial, volcanic, and carbonate settings are identified. Many different flow and transport models developed by Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), including original modeling of multiphase flow and transport by the Stoller-Navarro Joint Venture (SNJV), are integrated to form a general understanding of how the RST relates to the HST. This report is unlike the Frenchman Flat source term analysis because it does not calculate the HST for each test. Instead, this work only identifies the important processes that must be considered when the CAU-transport modeling is performed.
Download or read book Hydrologic Conditions and Distribution of Selected Radiochemical and Chemical Constituents in Water Snake River Plain Aquifer Idaho National Engineering Laboratory Idaho 1989 Through 1991 written by and published by . This book was released on 1995 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
