Download or read book Radionuclide Mobility at the Nevada Test Site written by D. Smith and published by . This book was released on 2003 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Underground nuclear tests conducted at the Nevada Test Site (NTS) are characterized by abundant fission product and actinide source terms. Included are {sup 99}Tc and other soluble radionuclides ({sup 3}H, {sup 14}C, {sup 36}Cl, {sup 85}Kr, and {sup 129}I), which are presumably mobile in groundwater and potentially toxic to down-gradient receptors. NTS provides the Office of Civilian Radioactive Waste Management (OCRWM) with an analog of the release of these radionuclides from a nuclear waste repository in the absence of engineered barriers. The investigation described in this report synthesizes a substantial body of data collected on the identity and distribution of soluble radionuclides at field scales over distances of hundreds of meters, for durations up to 40 years, and under hydrogeologic conditions very similar to the proposed geological repository at Yucca Mountain. This body of data is complemented by laboratory transport studies and a synthesis of recent modeling investigations from the NTS, with an emphasis on the ongoing Yucca Mountain Program (YMP) efforts. Overall, understanding the controls of radionuclide mobility associated with these nuclear tests will provide insight into the repository's future performance as well as bounds and calibrations for the numerical predictions of long-term radionuclide releases and migration.

Download or read book Field Scale Migration of 99Tc and 129I at the Nevada Test Site written by D. K. Smith and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As a result of 828 underground nuclear weapons tests conducted between 1951 and 1992 at the Nevada Test Site (NTS), more than 1E+6 TBq of long-lived radionuclides (actinide device residuals, fission and activation products, etc.) are residual. Included in the radiologic inventory are {sup 99}Tc (technetium) and {sup 129}I (iodine) that are presumably mobile in groundwater and potentially toxic to down-gradient receptors. Understanding the controls of radionuclide mobility associated with these nuclear tests provides insights into the behavior of these same radionuclides in groundwater associated with the proposed Yucca Mountain high-level nuclear waste repository as well as the fidelity of numerical predictions of long-term repository performance. We synthesize a substantial body of data collected on the distribution of {sup 99}Tc and {sup 129}I associated with radionuclide migration studies at NTS, at field scales over distances of hundreds of meters and for durations up to forty years, under hydrogeologic conditions very similar to the proposed geological repository at Yucca Mountain. The results show that Tc does not necessarily exist as a mobile and conservative species TcO{sub 4}{sup -}, as commonly assumed. This is not unexpected as the speciation and migration behavior of {sup 99}Tc will be significantly controlled by the redox conditions of the nuclear test-induced cavity (initial distribution) and surrounding groundwater (subsequent migration). Numerous lines of evidence suggest that the chemical environment of a nuclear test cavity is likely to have a reducing nature immediately following a detonation. These conditions may persist for decades after a test. Recent in situ redox potential measurements indicated that groundwaters at multiple locations of the NTS are not oxidizing as previously believed. Mobility of Tc species (TcO{sub 2} {center_dot} nH{sub 2}O) is greatly reduced in non-oxidizing environment. Speciation of iodine and the reactivity and mobility of {sup 129}I species is also complex in the groundwater at the NTS.

Download or read book Underground Radionuclide Migration at the Nevada Test Site written by and published by . This book was released on 1992 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document reviews results from a number of studies concerning underground migration of radionuclides from nuclear test cavities at the Nevada Test Site (NTS). Discussed are all cases known to the Department of Energy's Hydrology and Radionuclide Migration Program where radionuclides have been detected outside of the immediate vicinity of nuclear test cavities that are identifiable as the-source of the nuclides, as well as cases where radionuclides might have been expected and were intentionally sought but not fixed. There are nine locations where source-identifiable radionuclide migration has been detected, one where migration was purposely induced by pumping, and three where migration might be expected but was not found. In five of the nine cases of non-induced migration, the inferred migration mechanism is prompt fracture injection during detonation. In the other four cases, the inferred migration mechanism is water movement. In only a few of the reviewed cases can the actual migration mechanism be stated with confidence, and the attempt has been made to indicate the level of confidence for each case. References are cited where more information may be obtained. As an aid to future study, this document concludes with a brief discussion of the aspects of radionuclide migration that, as the present review indicates, are not yet understood. A course of action is suggested that would produce a better understanding of the phenomenon of radionuclide migration.

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 Evaluation of Cobalt Mobility in Soils from the Nevada Test Site written by and published by . This book was released on 1996 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear testing at and around the Nevada Test Site (NTS) resulted in widespread contamination from transuranic and other radionuclides, as well as from other toxic inorganic and organic contaminants. The type of contamination, including spatial distribution and type of radionuclides present, depends on the type of testing performed. Remediation of the contaminated areas is currently under way. The optimum in situ or ex situ remediation technology depends on the degree of interaction between the particular radionuclide, or contaminant in general, and the soil matrix, among other factors. The objective of this project was to evaluate the sorption affinity of NTS soils for common non-transuranic radionuclides. The sorption of cobalt (Co) on soils from two different areas of the NTS, namely the Little Feller and Cabriolet event sites, was studied. Experiments were conducted as a function of pH, solid concentration, total Co concentration, ionic strength, and particle size fraction. Preliminary results indicate that both soils have a high sorption capacity for Co. The results suggest that Co uptake is controlled by sorption on either internal, permanent-charge, ion-exchange sites of clay minerals or on amphoteric, surface-hydroxyl sites of oxides. The results further indicate strong retardation of Co in these soils, under most conditions tested and expected to be found in the respective soil environments. These conclusions are applicable to transport of radionuclides which are expected to bind strongly on oxide surfaces (e.g., Co) but the results may not be representative of the behavior of weakly binding radionuclides. These studies clearly demonstrate the importance of evaluating the mobility of radionuclides and the degree of radionuclide-soil interaction before final selection of an in situ or ex situ remediation technology for a contaminated site.

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 Recent Drilling Program to Investigate Radionuclide Migration at the Nevada Test Site written by and published by . This book was released on 1997 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent drilling affords new opportunities to investigate the occurrence, distribution and transport of radionuclides in the unsaturated and saturated zone at the Nevada Test Site (NTS), Nye County, Nevada. This program is unique becmise of the elevated activities of radionuclides encountered during drilling (> 3.7E+6 Bq/L 3H), extreme completion depths (> 950 m), the expense of constructing new wells (> $IE+6/borehole), and collaboration of government, academic, and industrial partners in the planning and execution of the program. The recent chilling is significant because it substantively augments earlier field of radionuclide migration at NTS, most notably the 1974 CAMBRIC RNM experiment Sites of five nuclear tests fired below or adjacent to the saturated zone have been drilled. Three of the events were fired in Yucca Flat which is a hydrologically closed basin and two were fired in fractured volcanics of Pahute Mesa. Results from Yucca Flat indicate that volatile and refractory radionuclides, fractionated at zero time, we not highly mobile under sawmted conditions. In contrast, borcholes completed on Pahute Mesa indicate Wgh concentrations of tritium (> 3.7E+6 Bq/L 3H) and other radionuclides may be rted more than 300 m from event cavities as dissolved species or as colloids.

Download or read book Overview of Radionuclide Migration Investigations Conductedon the Nevada Test Site written by Susan J. Erikson and published by . This book was released on 1989 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radionuclide Decay and In growth Technical Basis Document written by D. K. Smith and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this report is to assess the decay and in-growth of radionuclides from the radionuclide source term (RST) deposited by underground nuclear weapons tests conducted at the NTS from 1951 through 1992. A priority of the Underground Test Area (UGTA) project, administered by the Environmental Restoration Division of NNSA/NV, was to determine as accurately as possible a measure of the total radionuclide inventory for calculation of the RST deposited in the subsurface at the Nevada Test Site (NTS). The motivation for the development of a total radionuclide inventory is driven by a need to calculate the amount of radioactivity that will move away from the nuclear test cavities over time, referred to as the hydrologic source term (HST). The HST is a subset of the RST and must be calculated using knowledge of the geochemistry and hydrology of the subsurface environment. This will serve the regulatory process designed to protect human health from exposures to contaminated groundwater. Following the detonation of an underground nuclear test, and depending on the presence of water at the location of the detonation, the residual radionuclides may be found in aqueous or gaseous states, precipitated or chemically sorbed states, or incorporated in melt glass produced by the nuclear test. The decay and in-growth of radionuclides may have geochemical implications for the migration of radionuclides away from underground nuclear test cavities. For example, in the case of a long-lived mobile parent decaying to a shorter-lived and less mobile daughter, the geochemical properties of the parent element may control the migration potential of the daughter nuclide. It becomes important to understand the evolution of the RST in terms of effects on the mobility, solubility, or abundance of radionuclides in the HST that are created by decay and in-growth processes. The total radionuclide inventory and thus the RST changes with time due to radioactive decay. The abundance of a specific radionuclide at any given time is a function of the initial amount of radioactivity, the decay rate and in-growth from parent radionuclides. The in-growth of radioactivity is the additional amount of radioactivity for a given radionuclide that comes from the decay of the parent isotopes. In this report, decay and in-growth of radionuclides from the RST are evaluated over the 1000-year time frame in order to determine whether coupled in-growth and decay affect the relative abundance of any RST radionuclide. In addition, it is also necessary to identify whether any new derivative radionuclides not initially produced by the nuclear test but exist now as a result of in-growth from a parent radionuclide One of the major goals of this report is to simplify the transport modeler's task by pointing out where in-growth is unimportant and where it needs to be considered. The specific goals of this document are to evaluate radionuclide decay chains and provide specific recommendations for incorporating radionuclide daughters of concern in the calculation of the radionuclide inventory.

Download or read book Field Scale Migration of 99Tc and 129I at the Nevada Test Site written by and published by . This book was released on 2004 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The groundwater at the Nevada Test Site (NTS) contains many long-lived radionuclides, including 99Tc (technetium) and 129I (iodine), as a result of 828 underground nuclear weapons tests conducted between 1951 and 1992. We synthesized a body of data collected on the distribution of 99Tc and 129I in groundwater to assess their migration at NTS, at field scales over distances of hundreds of meters and for durations up to forty years and under hydrogeologic conditions very similar to the proposed geological repository at Yucca Mountain. The results of our study show that Tc does not necessarily exist as a mobile and conservative species TcO4−, as has been commonly assumed. This conclusion is corroborated by recent in situ redox potential measurements, which show that groundwaters at multiple locations of the NTS are not oxidizing, and mobility of reduced Tc species (TcO2 · nH2O) is greatly decreased. Speciation of iodine and its associated reactivity is also complex in the groundwater at the NTS, and its effect on the mobility of iodine should be the subject of future studies.

Download or read book Evaluation of Cobalt Mobility in Soils from the Nevada Test Site written by Charalambos Papelis and published by . This book was released on 1996 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Colloid nanoparticle formation and mobility in the context of deep geological nuclear waste disposal Project KOLLORADO 2 final report written by Huber, Florian and published by KIT Scientific Publishing. This book was released on 2014-03-03 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: To assess the relevance of colloidal influences on radionuclide transport for the long-term safety of a radioactive waste repository, the KOLLORADO-2 project integrates the results of geochemical and hydrogeological studies. The results may serve as a basis for an appraisal of the implications of colloid presence in the vicinity of radioactive waste repositories in different deep geological host-rock formations.

Download or read book Neptunium Transport Behavior in the Vicinity of Underground Nuclear Tests at the Nevada Test Site written by and published by . This book was released on 2010 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: We used short lived 239Np as a yield tracer and state of the art magnetic sector ICP-MS to measure ultra low levels of 237Np in a number of 'hot wells' at the Nevada National Security Site (NNSS), formerly known as the Nevada Test Site (NTS). The results indicate that 237Np concentrations at the Almendro, Cambric, Dalhart, Cheshire and Chancellor sites, are in the range of 3 x 10−5 to 7 x 10−2 pCi/L and well below the MCL for alpha emitting radionuclides (15 pCi/L) (EPA, 2009). Thus, while Np transport is believed to occur at the NNSS, activities are expected to be well below the regulatory limits for alpha-emitting radionuclides. We also compared 237Np concentration data to other radionuclides, including tritium, 14C, 36Cl, 99Tc, 129I, and plutonium, to evaluate the relative 237Np transport behavior. Based on isotope ratios relative to published unclassified Radiologic Source Terms (Bowen et al., 1999) and taking into consideration radionuclide distribution between melt glass, rubble and groundwater (IAEA, 1998), 237Np appears to be substantially less mobile than tritium and other non-sorbing radionuclides, as expected. However, this analysis also suggests that 237Np mobility is surprisingly similar to that of plutonium. The similar transport behavior of Np and Pu can be explained by one of two possibilities: (1) Np(IV) and Pu(IV) oxidation states dominate under mildly reducing NNSS groundwater conditions resulting in similar transport behavior or (2) apparent Np transport is the result of transport of its parent 241Pu and 241Am isotopes and subsequent decay to 237Np. Finally, measured 237Np concentrations were compared to recent Hydrologic Source Term (HST) models. The 237Np data collected from three wells in Frenchman Flat (RNM-1, RNM-2S, and UE-5n) are in good agreement with recent HST transport model predictions (Carle et al., 2005). The agreement provides confidence in the results of the predictive model. The comparison to Cheshire HST model predictions (Pawloski et al, 2001) is somewhat ambiguous due to the low concentration resolution of the particle transport model.

Download or read book Nevada Test Site Annual Site Environmental Report for Calendar Year written by and published by . This book was released on 2004 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nevada Test Site NTS and Off site Locations in the State of Nevada Tonopah Test Range Portions of the Nellis AFB Range NAFR Complex the Central Nevada Test Area and Shoal Area Nye County written by and published by . This book was released on 1996 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radioactive Particles in the Environment written by Deborah Oughton and published by Springer. This book was released on 2009-07-31 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive particles have been released to the environment from a number of sources, including nuclear weapon tests, nuclear accidents and discharges from nuclear installations. Particle characteristics influence the mobility, biological uptake and effects of radionuclides, hence information on these characteristics is essential for assessing environmental impact and risks. This publication presents a series of papers covering sources and source term characterisation, methodologies for characterizing particles, and the impact of particles on the behaviour of radioactive particles in the environment. Sources covered include the Chernobyl accident, nuclear weapons accidents at Thule and Palomares accident, the discharges from Dounreay and Krashnoyarsk, and depleted uranium in Kosovo and Kuwait. The overall aim is that an increased understanding of particle characteristics and behavior will help to reduce some of the uncertainties in environmental impact and risk assessment for particle contaminated areas.

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.