3,383 Matching Results

Search Results

Advanced search parameters have been applied.

Core flow experiment protocol

Description: This letter report describes the current status of the core flow through apparatus and describes the protocol and test matrix to be followed during the initial experimental stage of radionuclide transport studies in the Integrated Testing task.
Date: December 1, 1997
Creator: Viani, B.E. & Martin, S.I.
Partner: UNT Libraries Government Documents Department

Rapid diffusion method for physicochemical characterization of metal ligands in soils and sediments

Description: A diffusion method is described that allows preliminary characterization of metals in soils and sediments while minimizing the potential for alteration of metal form. In addition, examples of the application of the method to model compounds of Pu in the soil are given. (ERB)
Date: January 1, 1975
Creator: Garland, T.R.; Wildung, R.E. & Pelroy, R.A.
Partner: UNT Libraries Government Documents Department

Mathematical model for the transport of environmental plutonium

Description: From joint meeting of the American Nuclear Society and the Atomic Industrial Forum and Nuclear Energy Exhibition; San Francisco, California, USA (11 Nov 1973). A mathematical model describing the behavior of particulate Pu in the lower atmosphere is proposed which accounts for particles settling or impinging on the earth's surface as well as particle re-entrainment or resuspension. The assumptions used and system of equations derived are discussed. (LCL)
Date: April 30, 1974
Creator: Travis, J.R.
Partner: UNT Libraries Government Documents Department

One-dimensional model of the movement of trace radioactive solute through soil columns: the PERCOL model

Description: A one-dimensional mathematical model, PERCOL, has been developed to predict the movement of radionuclides through porous media as a function of measurable chemical parameters of the media. Laboratory column studies were conducted to verify the model. System parameters considered include soil type, radionuclide type, waste composition, flow rate, column length, and soil saturation. The agreement between measured radionuclide movement and that predicted by the model is considered good.(auth)
Date: January 1, 1972
Creator: Routson, R.C. & Serne, R.J.
Partner: UNT Libraries Government Documents Department

High resolution gamma spectroscopy well logging system

Description: A Gamma Spectroscopy Logging System (GSLS) has been developed to study sub-surface radionuclide contamination. The absolute counting efficiencies of the GSLS detectors were determined using cylindrical reference sources. More complex borehole geometries were modeled using commercially available shielding software and correction factors were developed based on relative gamma-ray fluence rates. Examination of varying porosity and moisture content showed that as porosity increases, and as the formation saturation ratio decreases, relative gamma-ray fluence rates increase linearly for all energies. Correction factors for iron and water cylindrical shields were found to agree well with correction factors determined during previous studies allowing for the development of correction factors for type-304 stainless steel and low-carbon steel casings. Regression analyses of correction factor data produced equations for determining correction factors applicable to spectral gamma-ray well logs acquired under non-standard borehole conditions.
Date: May 1, 1997
Creator: Giles, J.R. & Dooley, K.J.
Partner: UNT Libraries Government Documents Department

Atmospheric Transport of Radionuclides

Description: The purpose of atmospheric transport and diffusion calculations is to provide estimates of concentration and surface deposition from routine and accidental releases of pollutants to the atmosphere. This paper discusses this topic.
Date: March 3, 2003
Creator: Crawford, T.V.
Partner: UNT Libraries Government Documents Department

Intracrystalline diffusion in clinoptilolite: Implications for radionuclide isolation

Description: Experiments have been performed to measure the rate of exchange diffusion in the zeolite clinoptilolite (CL) for elements important to radionuclide isolation at Yucca Mountain, NV. Clinoptilolite is one of the major sorptive minerals in the tuffs at Yucca Mountain, and occurs both as a major component in zeolitized units (Calico Hills), and in fractures in non-zeolitized tuffs (Topopah Spring). Field evidence and numerical modeling suggests that the movement of fluids through the tuff rocks adjacent to the potential repository may occur via episodic flow through fractures. Under conditions of rapid fracture flow the effective sorptive capacity of fracture-lining clinoptilolite may be controlled by exchange diffusion rather than exchange equilibrium.
Date: November 16, 1995
Creator: Roberts, S.K.; Viani, B.E. & Phinney, D.
Partner: UNT Libraries Government Documents Department

Old F-Area Seepage Basin Transport Analyses in Support of a SCDHEC Mixing Zone Application

Description: This report documents the groundwater flow and transport results presented in the groundwater mixing zone application (GWMZ) for the Old F-Area Seepage Basin (OFASB) submitted to the South Carolina Department of Health and Environmental Control (SCDHEC) in March, 1997 (WSRC, 1997).
Date: December 4, 1998
Creator: Aleman, S.E.
Partner: UNT Libraries Government Documents Department

Recent drilling program to investigate radionuclide migration at the Nevada Test Site

Description: 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.
Date: April 1, 1997
Creator: Smith, D. K.
Partner: UNT Libraries Government Documents Department

Corrective action unit modeling approach for the underground test area, Nevada Test Site, Nye County, Nevada

Description: The modeling approach serves as a template for the development, application, and interpretation of the Corrective Action Unit (CAU) - scale saturated groundwater flow and transport model (herein called the CAU model) to be used for forecasting radionuclide migration in all Nevada Test Site (NTS) CAUs, consistent with the Federal Facility Agreement and Consent Order (FFACO) and Underground Test Area (UGTA) strategy. A summary of the project background, the FFACO and strategy, and the roles of participating agencies, is provided followed by a description of the contents of the document.
Date: March 1, 1998
Partner: UNT Libraries Government Documents Department

Laboratory evaluation of colloidal actinide transport at the Waste Isolation Pilot Plant (WIPP): 1. crushed-dolomite column flow...

Description: Colloid-facilitated transport of Pu, Am, U, Th, and Np has been recognized as a potentially important phenomenon affecting the performance of the Waste Isolation Pilot Plant (WIPP) facility being developed for safe disposal of transuranic radioactive waste. In a human intrusion scenario, actinide-bearing colloidal particles may be released from the repository and be transported by brines (approximately 0.8 to 3 molal ionic strength) through the Culebra, a thin fractured microcrystalline (mean grain size 2 micrometers) dolomite aquifer overlying the repository. Transport experiments were conducted using sieved, uniformly packed crushed Culebra rock or nonporous dolomite cleavage rhombohedra. Experiments with mineral fragments and fixed and live WIPP-relevant bacteria cultures showed significant levels of retardation due to physical filtration effects. Humic substances were not attenuated by the Culebra dolomite. Comparison of elution curves of latex microspheres in columns prepared with microcrystalline rock and nonporous rock showed minimal effect of Culebra micropores on colloid transport. These data form part of the basis to parameterize numerical codes being used to evaluate the performance of the WIPP.
Date: December 31, 1996
Creator: Yelton, W.G.; Behl, Y.K.; Kelly, J.W.; Dunn, M.; Gillow, J.B.; Francis, A.J. et al.
Partner: UNT Libraries Government Documents Department

Environmental monitoring of Columbia River sediments: Grain-size distribution and contaminant association

Description: Based on the results of this study and literature review, the following conclusions can be made: Sediment grain size and TOC (total organic carbon) influence contaminant fate and transport (in general, sediments with higher TOC content and finer grain-size distribution can have higher contaminant burdens than sediments from a given river section that have less TOC and greater amounts of coarse-grained sediments). Physiochemical sediment characteristics are highly variable among monitoring sites along the Columbia River. Sediment grain characterization and TOC analysis should be included in interpretations of sediment-monitoring data.
Date: April 1, 1995
Creator: Blanton, M. L.; Gardiner, W. W. & Dirkes, R. L.
Partner: UNT Libraries Government Documents Department

LLNL NESHAPs 1996 Annual Report

Description: This annual report is prepared pursuant to the National Emissions Standards for Hazardous Air Pollutants (NESHAPs) 40 CFR Part 61, Subpart H; Subpart H governs radionuclide emissions to air from Department of Energy (DOE) facilities. NESHAPs limits the emission of radionuclides to the ambient air from DOE facilities to levels resulting in an annual effective dose equivalent (EDE) of 10 mrem (10 microsieverts) to any member of the public. The EDEs for the Lawrence Livermore National Laboratory (LLNL) site-wide maximally exposed members of the public from 1996 operations were (1) Livermore site: 0. 093 mrem (0.93 microsievert) (52% from point-source emissions, 48% from diffuse-source emissions); (2) Site 300: 0.033 mrem (0.33 microsievert) (99% from point-source, 1% from diffuse-source emissions). The EDEs were generally calculated using the EPA-approved CAP88-PC air-dispersion/dose-assessment model. Site-specific meteorological data, stack flow data, and emissions estimates based on radionuclide inventory data or continuous-monitoring systems data were the specific input to CAP88-PC for each modeled source. 5 figs., 8 tabs.
Date: January 6, 1997
Creator: Gallegos, G.M.
Partner: UNT Libraries Government Documents Department

Survey of plutonium and uranium atom ratios and activity levels in Mortandad Canyon

Description: For more than three decades Mortandad Canyon has been the primary release area of treated liquid radioactive waste from the Los Alamos National Laboratory (Laboratory). In this survey, six water samples and seven stream sediment samples collected in Mortandad Canyon were analyzed by thermal ionization mass spectrometry (TIMS) to determine the plutonium and uranium activity levels and atom ratios. Be measuring the {sup 240}Pu/{sup 239}Pu atom ratios, the Laboratory plutonium component was evaluated relative to that from global fallout. Measurements of the relative abundance of {sup 235}U and {sup 236}U were also used to identify non-natural components. The survey results indicate the Laboratory plutonium and uranium concentrations in waters and sediments decrease relatively rapidly with distance downstream from the major industrial sources. Plutonium concentrations in shallow alluvial groundwater decrease by approximately 1000 fold along a 3000 ft distance. At the Laboratory downstream boundary, total plutonium and uranium concentrations were generally within regional background ranges previously reported. Laboratory derived plutonium is readily distinguished from global fallout in on-site waters and sediments. The isotopic ratio data indicates off-site migration of trace levels of Laboratory plutonium in stream sediments to distances approximately two miles downstream of the Laboratory boundary.
Date: September 22, 1997
Creator: Gallaher, B.M.; Benjamin, T.M.; Rokop, D.J. & Stoker, A.K.
Partner: UNT Libraries Government Documents Department

Actinide biocolloid formation in brine by halophilic bacteria

Description: The authors examined the ability of a halophilic bacterium (WIPP 1A) isolated from the Waste Isolation Pilot Plant (WIPP) site to accumulate uranium in order to determine the potential for biocolloid facilitated actinide transport. The bacterial cell surface functional groups involved in the complexation of the actinide were determined by titration. Uranium, added as uranyl nitrate, was removed from solution at pH 5 by cells but at pH 7 and 9 very little uranium was removed due to its limited solubility. Although present as soluble species, uranyl citrate at pH 5, 7, and 9, and uranyl carbonate at pH 9 were not removed by the bacterium because they were not bioavailable due to their neutral or negative charge. Addition of uranyl EDTA to brine at pH 5, 7, and 9 resulted in the immediate precipitation of U. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) analysis revealed that uranium was not only associated with the cell surface but also accumulated intracellularly as uranium-enriched granules. Extended X-ray absorption fine structure (EXAFS) analysis of the bacterial cells indicated the bulk sample contained more than one uranium phase. Nevertheless these results show the potential for the formation of actinide bearing bacterial biocolloids that are strictly regulated by the speciation and bioavailability of the actinide.
Date: December 31, 1998
Creator: Gillow, J.B.; Francis, A.J.; Dodge, C.J.; Harris, R.; Beveridge, T.J.; Brady, P.V. et al.
Partner: UNT Libraries Government Documents Department

Technetium getters in the near surface environment

Description: Conventional performance assessments assume that radioactive {sup 99}Tc travels as a non-sorbing component with an effective K{sub d} (distribution coefficient) of 0. This is because soil mineral surfaces commonly develop net negative surface charges and pertechnetate (TcO{sub 4}), with large ionic size and low electrical density, is not sorbed onto them. However, a variety of materials have been identified that retain Tc and may eventually lead to promising Tc getters. In assessing Tc getter performance it is important to evaluate the environment in which the getter is to function. In many contaminant plumes Tc will only leach slowly from the source of the contamination and significant dilution is likely. Thus, sub-ppb Tc concentrations are expected and normal groundwater constituents will dominate the aquifer chemistry. In this setting a variety of constituents were found to retard TcO{sub 4}: imogolite, boehmite, hydrotalcite, goethite, copper sulfide and oxide and coal. Near leaking tanks of high level nuclear waste, Tc may be present in mg/L level concentrations and groundwater chemistry will be dominated by constituents from the waste. Both bone char, and to a lesser degree, freshly precipitated Al hydroxides may be effective Tc scavengers in this environment. Thus, the search for Tc getters is far from hopeless, although much remains to be learned about the mechanisms by which these materials retain Tc.
Date: May 19, 2000
Partner: UNT Libraries Government Documents Department

Uranium characterization at the St. Louis Airport Site

Description: In support of the Department of Energy/Office of Technology Development`s Expedited Site Characterization (ESC) project (coordinated by Ames Laboratory), the Pacific Northwest Laboratory demonstrated two complementary technologies at the St. Louis Airport (SLAP) site that have been designed and optimized for the rapid, in situ quantification of radionuclide contamination in surface soils. The sensors are optimized for the detection of high-energy beta particles or gamma rays emitted from the decay of specific radionuclides of interest. These technologies were demonstrated by measuring the beta and gamma fluxes at several locations within the SLAP site. Measurements were converted to average contamination levels, using detector calibrations performed with spiked samples (beta) or sealed sources (gamma). Additionally, subsurface activity levels were derived from discrete soil samples (provided by the ESC field crew) via gamma-ray spectrometry in a controlled laboratory setting. Since the beta and gamma sensor technologies are intrinsically sensitive to different types of radiation and activity distributions (i.e., surface and shallow subsurface, respectively), the data obtained from the two detectors provide complementary information about the distribution of the contamination. The results reported here suggest that a number of locations within the SLAP site have elevated levels of {sup 211}U, and the differences between the beta and gamma activities indicate that the contamination is largely located near the surface of the soil.
Date: May 1, 1995
Creator: Schilk, A.J.; Hubbard, C.W.; Bowyer, T.W. & Reiman, R.T.
Partner: UNT Libraries Government Documents Department

QA lessons learned for parameter control from the WIPP Project

Description: This paper provides a summary of lessons learned from experiences on the Waste Isolation Pilot Plant (WJPP) Project in implementation of quality assurance controls surrounding inputs for performance assessment analysis. Since the performance assessment (PA) process is inherent in compliance determination for any waste repository, these lessons-learned are intended to be useful to investigators, analysts, and Quality Assurance (QA) practitioners working on high level waste disposal projects. On the WIPP Project, PA analyses for regulatory-compliance determination utilized several inter-related computer programs (codes) that mathematically modeled phenomena such as radionuclide release, retardation, and transport. The input information for those codes are the parameters that are the subject of this paper. Parameters were maintained in a computer database, which was then queried electronically by the PA codes whenever input was needed as the analyses were run.
Date: January 1, 1998
Creator: Richards, R.R.
Partner: UNT Libraries Government Documents Department

Modeling atmospheric deposition using a stochastic transport model

Description: An advanced stochastic transport model has been modified to include the removal mechanisms of dry and wet deposition. Time-dependent wind and turbulence fields are generated with a prognostic mesoscale numerical model and are used to advect and disperse individually released particles that are each assigned a mass. These particles are subjected to mass reduction in two ways depending on their physical location. Particles near the surface experience a decrease in mass using the concept of a dry deposition velocity, while the mass of particles located within areas of precipitation are depleted using a scavenging coefficient. Two levels of complexity are incorporated into the particle model. The simple case assumes constant values of dry deposition velocity and scavenging coefficient, while the more complex case varies the values according to meteorology, surface conditions, release material, and precipitation intensity. Instantaneous and cumulative dry and wet deposition are determined from the mass loss due to these physical mechanisms. A useful means of validating the model results is with data available from a recent accidental release of Cesium-137 from a steel-processing furnace in Algeciras, Spain in May, 1998. This paper describes the deposition modeling technique, as well as a comparison of simulated concentration and deposition with measurements taken for the Algeciras release.
Date: December 17, 1999
Creator: Buckley, R. L.
Partner: UNT Libraries Government Documents Department