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Modelling The Environmental Transport Of Tritium In The Vicinity Of Long Term Atmospheric And Sub Surface Sources
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Author :Biosphere Modelling and Assessment (Program). Tritium Working Group Publisher :IAEA ISBN 13 : Total Pages :316 pages Book Rating :4.3/5 (91 download)
Book Synopsis Modelling the Environmental Transport of Tritium in the Vicinity of Long Term Atmospheric and Sub-surface Sources by : Biosphere Modelling and Assessment (Program). Tritium Working Group
Download or read book Modelling the Environmental Transport of Tritium in the Vicinity of Long Term Atmospheric and Sub-surface Sources written by Biosphere Modelling and Assessment (Program). Tritium Working Group and published by IAEA. This book was released on 2003 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: The BIOMASS (Biosphere Modelling and Assessment Methods) programme seeks to improve methods of assessing the impact of radionuclides in the environment (any man-made or natural element that emits radiation and that may cause cancer after long term exposure through drinking water). This report describes the results of studies undertaken by the Tritium working group established to identify gaps in modelling approaches regarding the transfer of radionuclides in particular parts of the biosphere of potential radiological significance. It discusses six model test exercises and the field sampling programme undertaken to environmental spread of tritium in long term atmospheric and sub-surface sources.
Book Synopsis Tritium Distribution in the Environment in the Vicinity of a Chronic Atmospheric Source-assessment of the Steady State Hypothesis by :
Download or read book Tritium Distribution in the Environment in the Vicinity of a Chronic Atmospheric Source-assessment of the Steady State Hypothesis written by and published by . This book was released on 1990 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Savannah River Site (SRS) is a major radionuclide production center. Tritium has been released to the atmosphere over the 36 year period of operation. The tritiated water concentration of the atmosphere, rain, vegetation and food have been routinely monitored during this period. Special studies have been made of tritium in soils and in the organic fractions of these same materials. The available data suggest that the average tritium concentration in the components of the terrestrial environment have approached a steady state with the two main sources of tritium, rainfall and atmospheric water vapor.
Book Synopsis Environmental Transport and Cycling of Tritium in the Vicinity of Atmospheric Releases. [Savannah River Plant]. by :
Download or read book Environmental Transport and Cycling of Tritium in the Vicinity of Atmospheric Releases. [Savannah River Plant]. written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Routine releases of tritium to the atmosphere from the Savannah River Plant (SRP) have averaged 5.12 x 105 curies per year during the period 1974 to 1977. Patterns of tritium dispersion in the environment surrounding SRP indicate a power law relationship between air concentration and distance from the source. The relationship between the concentration of tritiated water in vegetation and distance is more complex. A model of the tritium dispersion and cycling in the environment explains the dispersion patterns in terms of the ratio of tritiated hydrogen to tritiated water, climate, and vegetation characteristics. The annual variation in the environmental patterns around the SRP is almost completely determined by the fraction of tritiated hydrogen in the release.
Book Synopsis Vertical Tritium Transport from the Shallow Unsaturated Zone to the Atmosphere, Amargosa Desert Research Site, Nevada by : Christina Amanda Garcia
Download or read book Vertical Tritium Transport from the Shallow Unsaturated Zone to the Atmosphere, Amargosa Desert Research Site, Nevada written by Christina Amanda Garcia and published by . This book was released on 2007 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the impact of desert vegetation on tritium transport and fate is essential when considering radioactive waste isolation in the western United States. This study uses filed data to estimate the magnitude and spatio-temporal variability of tritiated-water vapor tritium transport from the shallow unsaturated zone to the atmosphere adjacent to a radioactive waste facility and numerical modeling to clarify tritium transport mechanisms beneath desert vegetation. A 2-year tritiated-water vapor mass was released within the study area and quantified using evaporation, transpiration, and tritiated-water vapor concentrations in plants and shallow soil. Numerical simulation results indicate that root uptake by desert vegetation can lead to upward water movement below the root zone. This can increase the upward tritiated-water vapor flux. Amplified upward fluxes prevent long term shallow subsurface moisture accumulation, limiting moisture penetration below the root zone and the potential for groundwater contamination.--Adapted from the abstract.
Book Synopsis The Office of Environmental Management Technical Reports by :
Download or read book The Office of Environmental Management Technical Reports written by and published by . This book was released on 1997 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Global Environmental Transport Models for Tritium by :
Download or read book Global Environmental Transport Models for Tritium written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we discuss some of the obstacles to the construction of credible models of global tritium transport for use in dose assessments. We illustrate these difficulties by comparing model predictions of environmental tritium levels with measurements. Monitoring of tritium has shown that specific activities in precipitation over land are typically higher by a factor of three to four than those in precipitation over the oceans. Experience with modeling CO2 turnover in the oceans has led to the conclusion that two-box reservoir models of the ocean often give unsatisfactory representations of transient solutions. Failure to consider these factors in global models can lead to distorted estimates of collective dose and create difficulties in validation of the model against real data. We illustrate these problems with a seven-box model recommended by the National Council on Radiation Protection and Measurements in which we forced the atmospheric compartment to reproduce an exogenous function based on historic observations of HTO in precipitation at 50°N. The fresh water response underestimates data from the Ottawa River by a factor of about five, and the ocean surface response overestimates tritium data from the surface waters of the Northern Pacific by nearly an order of magnitude. Revision of the model to include (1) separate over-land and over-ocean compartments of the atmosphere and (2) a box-diffusion model of the subsurface ocean brings the discrepant responses into good agreement with the environmental data. In a second exercise, we used a latitudinally disaggregated model and replaced a tropospheric compartment in the northern hemisphere by historic precipitation data. The model's response greatly underestimates the tritium specific activity in the southern hemisphere. These exercises lead us to doubt that a proper global transport model for tritium is available at present for collective dose assessment. 12 refs., 3 figs.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis HMSO Agency Catalogue by : Great Britain. Her Majesty's Stationery Office
Download or read book HMSO Agency Catalogue written by Great Britain. Her Majesty's Stationery Office and published by . This book was released on 2003 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Atomic Energy Agency Publications by : International Atomic Energy Agency
Download or read book International Atomic Energy Agency Publications written by International Atomic Energy Agency and published by . This book was released on 2004 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Terrestrial and Freshwater Environments by : International Atomic Energy Agency
Download or read book Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Terrestrial and Freshwater Environments written by International Atomic Energy Agency and published by . This book was released on 2010 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides data for use in assessments of routine discharges of radionuclides to terrestrial and freshwater environments. Some of the data may also be useful for assessing the impacts of accidental releases and releases in the future.
Book Synopsis MODELING ATMOSPHERIC RELEASES OF TRITIUM FROM NUCLEAR INSTALLATIONS. by :
Download or read book MODELING ATMOSPHERIC RELEASES OF TRITIUM FROM NUCLEAR INSTALLATIONS. written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Tritium source term analysis and the subsequent dispersion and consequence analyses supporting the safety documentation of Department of Energy nuclear facilities are especially sensitive to the applied software analysis methodology, input data and user assumptions. Three sequential areas in tritium accident analysis are examined in this study to illustrate where the analyst should exercise caution. Included are: (1) the development of a tritium oxide source term; (2) use of a full tritium dispersion model based on site-specific information to determine an appropriate deposition scaling factor for use in more simplified, broader modeling, and (3) derivation of a special tritium compound (STC) dose conversion factor for consequence analysis, consistent with the nature of the originating source material. It is recommended that unless supporting, defensible evidence is available to the contrary, the tritium release analyses should assume tritium oxide as the species released (or chemically transformed under accident's environment). Important exceptions include STC situations and laboratory-scale releases of hydrogen gas. In the modeling of the environmental transport, a full phenomenology model suggests that a deposition velocity of 0.5 cm/s is an appropriate value for environmental features of the Savannah River Site. This value is bounding for certain situations but non-conservative compared to the full model in others. Care should be exercised in choosing other factors such as the exposure time and the resuspension factor.
Book Synopsis MODELING TRITIUM TRANSPORT, DEPOSITION AND RE-EMISSION. by :
Download or read book MODELING TRITIUM TRANSPORT, DEPOSITION AND RE-EMISSION. written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The atmospheric release of tritium oxide (HTO) potentially impacts human health, typically through inhalation or absorption. Due to HTO's similarity to water, vegetation will absorb HTO by solution in the leaf water and then re-emit it, creating a number of secondary sources of HTO. Currently, models used for emergency response at Savannah River Site incorporate the transport and deposition of HTO but do not provide estimates for its potential re-emission from vegetation or soil surface though re-emission could result in prolonged exposure and greater than predicted dose for an individual downwind. A simple model of HTO transport, deposition and re-emission has been developed to examine the potential increase in exposure and dose. The model simulates an initial release of HTO that moves with a mean wind and expands through diffusion as a Gaussian puff. Deposition is modeled using previous estimates of deposition velocity for HTO and re-emission is modeled using a time constant that describes how quickly HTO is transferred between the surface and atmosphere. Additional puffs are created to simulate re-emission of HTO as well as horizontal diffusion across model grid cells. An evaluation of field data indicates that the use of a re-emission module tends to improve model predictions through improved prediction of peak concentration magnitude and location. When considering dose, nearly all of the released material is included in the dose calculation when re-emission is included. Although exposure to HTO through re-emission occurs over a few hours, the incremental increase in dose is relatively small because the atmospheric concentration of re-emitted HTO is much lower than the initial release.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1985-02 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Selected Water Resources Abstracts by :
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 962 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Stationery Office Agency Catalogue by : Stationery Office (Great Britain)
Download or read book The Stationery Office Agency Catalogue written by Stationery Office (Great Britain) and published by . This book was released on 2003 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of the Environmental Fate of Tritium in the Atmosphere by : Canadian Nuclear Safety Commission
Download or read book Investigation of the Environmental Fate of Tritium in the Atmosphere written by Canadian Nuclear Safety Commission and published by . This book was released on 2009 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the various anthropogenic and natural sources of tritium in the atmosphere, the chemical forms of tritium in the atmosphere, and the physical and chemical behaviour of tritium in the atmosphere. This includes discussion of atmospheric dispersion processes and modeling approaches to estimating dispersion in the context of public dose assessment. The report also describes the dynamic behaviour of tritium in the hydrological cycle, including transfer of tritium from air to soil water and surface water, tritium transport from soil water to groundwater, and tritium behaviour in lake and river receiving environments. Beyond this literature review of tritium behaviour in atmospheric and hydrological environments, this report considers available tritium monitoring data for a number of licensed nuclear facilities releasing tritium, examines model predictions of environmental concentrations of tritium, and compares predicted and observed concentrations. The report is organized as follows: Section 2.0 describes the various sources of tritium, Section 3.0 describes the physical and chemical behaviour of tritium in the atmosphere, and Section 4.0 describes the behaviour of tritium in the hydrological cycle, and Section 5.0 compares predicted and observed behaviour at various release sites.--Includes text from document.
Book Synopsis Tritium Atmospheric Transport and Deposition Following Acute Releases by :
Download or read book Tritium Atmospheric Transport and Deposition Following Acute Releases written by and published by . This book was released on 1990 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: During 35 years of operation of the Savannah River Site (SRS) there have been a small number of inadvertent tritium releases to the atmosphere. After detection of the releases by stack monitors, field crews were dispatched to determine the concentration of tritium in the environment. The objective of the measurement was to verify environmental concentrations calculated by dose assessment models. Air samples were used to verify the concentration levels and tritium forms during the plume passage. It was not feasible to take enough samples in the plume path to determine the two dimensional distribution of tritium concentration in the plume. However, the ground level distribution was very well reflected vegetation samples. Therefore, it is unusually possible to determine plume shape, plume width, and the relative maximum concentration as the plume moves downwind from the vegetation samples. In eight of the nine releases studied, the monitoring data allowed comparison with atmospheric transport models.
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