Download or read book 1979 80 written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of Hydrologic Transport of Radionuclides from the Gnome Underground Nuclear Test Site written by and published by . This book was released on 1996 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of Hydrologic Transport of Radionuclides from the Rulison Underground Nuclear Test Site Colorado written by Sam Earman and published by . This book was released on 1996 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of Hydrologic Transport of Radionuclides from the Gasbuggy Underground Nuclear Test Site New Mexico written by and published by . This book was released on 1996 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Department of Energy (DOE) is operating an environmental restoration program to characterize, remediate, and close non-Nevada Test Site locations that were used for nuclear testing. Evaluation of radionuclide transport by groundwater from these sites is an important part of the preliminary risk analysis. These evaluations are undertaken to allow prioritization of the test areas in terms of risk, provide a quantitative basis for discussions with regulators and the public about future work at the sites, and provide a framework for assessing data needs to be filled by site characterization. The Gasbuggy site in northwestern New Mexico was the location of an underground detonation of a 29-kiloton nuclear device in 1967. The test took place in the Lewis Shale, approximately 182 m below the Ojo Alamo Sandstone, which is the aquifer closest to the detonation horizon. The conservative assumption was made that tritium was injected from the blast-created cavity into the Ojo Alamo Sandstone by the force of the explosion, via fractures created by the shot. Model results suggest that if radionuclides produced by the shot entered the Ojo Alamo, they are most likely contained within the area currently administered by DOE. The transport calculations are most sensitive to changes in the mean groundwater velocity, followed by the variance in hydraulic conductivity, the correlation scale of hydraulic conductivity, the transverse hydrodynamic dispersion coefficient, and uncertainty in the source size. This modeling was performed to investigate how the uncertainty in various physical parameters affects calculations of radionuclide transport at the Gasbuggy site, and to serve as a starting point for discussion regarding further investigation at the site; it was not intended to be a definitive simulation of migration pathways or radionuclide concentration values.
Download or read book Histoire e de la p dagogie du l7e si cle nos jours written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of Hydrologic Transport of Radionuclides from the Rio Blanco Underground Nuclear Test Site Colorado written by Jenny B. Chapman and published by . This book was released on 1996 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of Hydrologic Transport of Radionuclides from the Gasbuggy Underground Nuclear Test Site New Mexico written by Sam Earman and published by . This book was released on 1996 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Groundwater Flow and Transport of Radionuclides at Amchitka Island s Underground Nuclear Tests written by and published by . This book was released on 2002 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since 1963, all United States nuclear tests have been conducted underground. A consequence of this testing has been the deposition of large amounts of radioactive material in the subsurface, sometimes in direct contact with groundwater. The majority of this testing occurred on the Nevada Test Site (NTS), but a limited number of experiments were conducted in other locations. One of these locations, Amchitka Island, Alaska is the subject of this report. Three underground nuclear tests were conducted on Amchitka Island. Long Shot was an 80-kiloton-yield test conducted at a depth of 700 meters (m) on October 29, 1965 (DOE, 2000). Milrow had an announced yield of about 1,000 kilotons, and was detonated at a depth of 1,220 m on October 2, 1969. Cannikin had an announced yield less than 5,000 kilotons, and was conducted at a depth of 1,790 m on November 6, 1971. The purpose of this work is to provide a portion of the information needed to conduct a human-health risk assessment of the potential hazard posed by the three underground nuclear tests on Amchitka Island. Specifically, the focus of this work is the subsurface transport portion, including the release of radionuclides from the underground cavities and their movement through the groundwater system to the point where they seep out of the ocean floor and into the marine environment. This requires a conceptual model of groundwater flow on the island using geologic, hydrologic, and chemical information, a numerical model for groundwater flow, a conceptual model of contaminant release and transport properties from the nuclear test cavities, and a numerical model for contaminant transport. Needed for the risk assessment are estimates of the quantity of radionuclides (in terms of mass flux) from the underground tests on Amchitka that could discharge to the ocean, the time of possible discharge, and the location in terms of distance from shoreline. The radionuclide data presented here are all reported in terms of normalized masses to avoid presenting classified information. As only linear processes are modeled, the results can be readily scaled by the true classified masses for use in the risk assessment. The modeling timeframe for the risk assessment was set at 1,000 years, though some calculations are extended to 2,000 years. This first section of the report endeavors to orient the reader with the environment of Amchitka and the specifics of the underground nuclear tests. Of prime importance are the geologic and hydrologic conditions of the subsurface. A conceptual model for groundwater flow beneath the island is then developed and paired with an appropriate numerical modeling approach in section 2. The parameters needed for the model, supporting data for them, and data uncertainties are discussed at length. The calibration of the three flow models (one for each test) is then presented. At this point the conceptual radionuclide transport model is introduced and its numerical approach described in section 3. Again, the transport parameters and their supporting data and uncertainties are the focus. With all of the processes and parameters in place, the first major modeling phase can be discussed in section 4. In this phase, a parametric uncertainty analysis is performed to determine the sensitivity of the transport modeling results to the uncertainties present in the parameters. This analysis is motivated by the recognition of substantial uncertainty in the subsurface conditions on the island and the need to incorporate that uncertainty into the modeling. The conclusion of the first phase determines the parameters to hold as uncertain through the main flow and transport modeling. This second, main phase of modeling is presented in section 5, with the contaminant breakthrough behavior of each test site addressed. This is followed by a sensitivity analysis in section 6, regarding the importance of additional processes that could not be supported in the main modeling effort due to lack of data. Finally, the results for the individual sites are compared, the sensitivities discussed, and final conclusions presented in section 7.
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 Hydrologic Transport of Radionuclides from Nuclear Craters and Quarries written by R. E. Sebenthall and published by . This book was released on 1970 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Subsurface Transport of Radionuclides at the Nevada Test Site written by Margaret Ann Guell and published by . This book was released on 1997 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Underground nuclear detonations at the Nevada Test Site (NTS) provide a unique opportunity to study the behavior of radionuclides in a field environment. The 1965 Cambric event, a small detonation in the saturated zone of the Valley Fill alluvial aquifer at NTS, has been studied extensively to improve the understanding of groundwater flow and radionuclide migration. The 1974 field investigation of the Cambric event included: (1) a re-entry boring into the original detonation cavity and (2) the installation of a pumping well 91 meters away from the cavity to draw mobile radionuclides such as tritium and krypton-85. This satellite well, sampled regularly over 16 years, produced some unexpected results. Because of the supposed ideality of tritium and krypton as tracers, their arrival was expected to be concurrent; however, krypton-85 arrival was delayed compared to tritium. More important is the fact that, while over 90% of the decay-corrected tritium from the original blast was drawn out through the well, less than half of the krypton was recovered. This work presents a hypothesis for understanding these unexpected results based on the site hydrogeology and underground detonation phenomenology. Carbon dioxide evolved from caliche during the detonation appears to have caused the upward migration of krypton-85 and other gaseous radionuclides through the collapsing chimney and into the unsaturated zone above. In the process, krypton became distributed throughout the cavity and chimney, while tritium remained immediately around the cavity. This post-detonation movement of krypton-85 provides one explanation, then, of the unexpected elution curve results. To demonstrate the validity of this hypothesis, a variety of numerical simulations were performed using the finite difference code TRACR3D. Calibrating two unknown hydraulic conductivity parameters on the tritium field data, it was shown that krypton-85 may indeed have been distributed throughout the chimney as suggested by the hypothesis."--Abstract.
Download or read book A Serendipitous Long Term Infiltration Experiment written by and published by . This book was released on 2008 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Underground nuclear weapons testing at the Nevada Test Site introduced numerous radionuclides that may be used to characterize subsurface hydrologic transport processes in arid climates. A sixteen year pumping experiment designed to examine radionuclide migration away from the CAMBRIC nuclear test, conducted in groundwater beneath Frenchman Flat in 1965, gave rise to an unintended second experiment involving radionuclide infiltration through the vadose zone, as induced by seepage of pumping effluents beneath an unlined discharge trench. The combined experiments have been reanalyzed using a detailed, three-dimensional numerical model of transient, variably saturated flow and mass transport, tailored specifically for large scale and efficient calculations. Simulations have been used to estimate radionuclide travel and residence times in various parts of the system for comparison with observations in wells. Model predictions of mass transport were able to clearly demonstrate radionuclide recycling behavior between the ditch and pumping well previously suggested by isotopic age dating information; match travel time estimates for radionuclides moving between the ditch, the water table, and monitoring wells; and provide more realistic ways in which to interpret the pumping well elution curves. Collectively, the results illustrate the utility of integrating detailed numerical modeling with diverse observational data in developing accurate interpretations and forecasts of contaminant migration processes.
Download or read book TYBO BENHAM written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent field studies have led to the discovery of trace quantities of plutonium originating from the BENHAM underground nuclear test in two groundwater observation wells on Pahute Mesa at the Nevada Test Site. These observation wells are located 1.3 km from the BENHAM underground nuclear test and approximately 300 m from the TYBO underground nuclear test. In addition to plutonium, several other conservative (e.g. tritium) and reactive (e.g. cesium) radionuclides were found in both observation wells. The highest radionuclide concentrations were found in a well sampling a welded tuff aquifer more than 500m above the BENHAM emplacement depth. These measurements have prompted additional investigations to ascertain the mechanisms, processes, and conditions affecting subsurface radionuclide transport in Pahute Mesa groundwater. This report describes an integrated modeling approach used to simulate groundwater flow, radionuclide source release, and radionuclide transport near the BENHAM and TYBO underground nuclear tests on Pahute Mesa. The components of the model include a flow model at a scale large enough to encompass many wells for calibration, a source-term model capable of predicting radionuclide releases to aquifers following complex processes associated with nonisothermal flow and glass dissolution, and site-scale transport models that consider migration of solutes and colloids in fractured volcanic rock. Although multiple modeling components contribute to the methodology presented in this report, they are coupled and yield results consistent with laboratory and field observations. Additionally, sensitivity analyses are conducted to provide insight into the relative importance of uncertainty ranges in the transport parameters.
Download or read book U S Geological Survey Professional Paper written by and published by . This book was released on 1964 with total page 1018 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessing Field scale Migration of Mobile Radionuclides at the Nevada Test Site written by and published by . This book was released on 2006 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerous long-lived radionuclides, including 99Tc (technetium) and 129I (iodine), are present in groundwater at the Nevada Test Site (NTS) as a result of 828 underground nuclear weapons tests conducted between 1951 and 1992. We synthesize a body of groundwater data collected on the distribution of a number of radionuclides (3H, 14C, 36Cl, 99Tc and 129I), which are presumably mobile in the subsurface and potentially toxic to down-gradient receptors, to assess their migration at NTS, at field scales over distances of hundreds of meters and for durations of more than thirty years. Qualitative evaluation of field-scale migration of these radionuclides in the saturated zone provides an independent approach to validating their presumably conservative transport in the performance assessment of the proposed geological repository at Yucca Mountain, which is located on the western edge of NTS. The analyses show that the interaction of 3H with a solid surface via an isotopic exchange with clay lattice hydroxyls may cause a slight delay in the transport of 3H. The transport of 14C could be retarded by its isotopic exchange with carbonate minerals, and the exchange may be more pronounced in the alluvial aquifer. In particular, 99Tc may not necessarily exist as a mobile and conservative species 99TcO4−, as commonly assumed for NTS groundwater. This is corroborated with recent in situ redox potential measurements, both across and near Yucca Mountain, showing that groundwater at multiple locations is not oxidizing. Speciation of iodine and its associated reactivity and mobility is also complex in the groundwater at the NTS and deserves further attention. The assumption of no retardation for the transport of 99Tc (especially) and 129I, used at the performance assessment of Yucca Mountain repository, is probably overly conservative and results in unrealistically high estimated doses for down-gradient receptors.
Download or read book Geological Survey Professional Paper written by and published by . This book was released on 1964 with total page 1024 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrologic Transport of Radionuclides from Nuclear Craters and Quarries written by Paul Kruger and published by . This book was released on 1970 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Feasibility studies of proposed applications of nuclear explosions for civil construction require the capability to predict the safety of the applications. One specific need for nuclear excavation projects is the development of adequate methods for estimating the hydrologic transport of radionuclides from excavation sites. Such models must consider the complexity of the nuclear, hydrologic, and environmental processes involved and predict, with reliability, the concentrattion of radionuclides in surface and ground waters at locations downstream of a nuclear crater or quarry. The report presents a review of the literature related to the development of numerical and experimental methods for predicting hydrologic transport of radionuclides with specific application to nuclear excavation and quarrying. (Author).
