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 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.
Download or read book Computer Modeling of Environmental Tritium Transport Following Chronic Releases Using NORMTRI and CAP88PC 2 written by Stacey L. Fox and published by . This book was released on 2001 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1987 with total page 1390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
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.
Download or read book A Continental scale Groundwater Flow and Tritium Transport Model written by Mark Ranjram and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This work introduces GromPy, a new continental-scale groundwater flow and tritium transport modelling platform in python. GromPy takes advantage of the python environment, which is both robust and free-to-access, as well as numerical solver algorithms currently unused in groundwater flow simulations. An overview of the novel processes of the code, the governing equations, and fundamental benchmarking exercises is provided. To evaluate the efficacy of the model in a real-world application, a model of the Nebraska portion of the High Plains aquifer is developed as a case study. The steady-state groundwater heads produced in the groundwater flow portion of the model are compared against pre-development groundwater heads measured in the aquifer. A sensitivity analysis composed of 22 model runs is conducted to create an input data set that produces minimum differences between modelled and observed heads. The best-matching heads are used to define the steady-state flow field in the transient transport model. The tritium transport model evaluates 53 years of atmospheric tritium recharge and transport in the domain, capturing the spike and decay in atmospheric tritium concentrations in the late 1950s and early 1960s associated with worldwide thermonuclear weapons testing. By using tritium concentrations, this work intended to evaluate relative groundwater ages in the domain, with higher concentrations correlating to older groundwater. Unfortunately, the results of the tritium transport model are severely limited by constraints of numerical stability and available computational resources, such that no defensible truth can be culled from the analysis. In this light, this work attempts to comment on the difficulties of the process of continental scale flow and transport modelling, and comment on the experimental conditions that limited a truer representation of groundwater flow and tritium transport in the model results." --
Download or read book Energy Research Abstracts written by and published by . This book was released on 1992-10 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Inventory of Federal Energy related Environment and Safety Research for written by and published by . This book was released on 1980 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Inventory of Federal Energy related Environment and Safety Research for FY 1978 written by and published by . This book was released on 1979 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Inventory of Federal Energy related Environment and Safety Research for FY 1978 Project listings and indexes written by and published by . This book was released on 1979 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Inventory of Federal Energy related Environment and Safety Research for FY 1977 written by United States Department of Energy. Environmental Impacts Division and published by . This book was released on 1978 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Brief Review of Environmental Transport of Tritium at the Los Alamos LLRW Disposal Facility written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1985 with total page 900 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book INIS Atomindex written by and published by . This book was released on 1987 with total page 1136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Global Cycling of Tritium and Iodine 129 written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic linear compartmnt models are used widely to describe global cycling of environmental tritium and 129I. Important tests of these models by comparison of predictions with environmental data from anthropogenic sources are discussed. A tritium model, based on the global hydrologic cycle that reproduces time-series data from atmospheric nuclear weapons testing on concentrations in precipitation, ocean surface waters, and surface fresh waters in the northern hemisphere, concentrations of atmospheric tritium in the southern hemisphere, and the latitude-dependence of atmosperic tritium in both hemispheres is presented. The model includes: hemispheric stratosphere compartments; disaggregation of the troposphere and ocean surface waters into eight latitude zones; consideration of the different concentrations of water in air over land and the ocean in calculating the specific activity of atmospheric tritium; and use of a box-diffusion model for transport in the ocean. An important prediction of a global model for 129I, which we developed previously from data on cycling of naturally occurring stable iodine, is that the mean residence time in the first 1 m of surface soil is about 4000 y. However, a recent analysis of measured soil profiles of 129I near the Savannah River Plant, based on a linear compartment model for downward transport through soil, suggested that the mean residence time in the first 0.3 m is only about 40 y. A diffusion model is used to describe the measured soil profiles, and the resulting diffusion coefficient is shown to correspond to mean residence times in the first 0.3 m and 1 m of soil of about 80 and 900 y, respectively. The value for the first 1 m can be reconciled with the prediction of the global model.
Download or read book Radionuclides in the Environment written by David A. Atwood and published by John Wiley & Sons. This book was released on 2013-02-19 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear energy is the one energy source that could meet the world's growing energy needs and provide a smooth transition from fossil fuels to renewable energy in the coming decades and centuries. It is becoming abundantly clear that an increase in nuclear energy capacity will, and probably must, take place. However, nuclear energy and the use of radionuclides for civilian and military purposes lead to extremely long-lived waste that is costly and highly problematic to deal with. Therefore, it is critically important ot understand the environmental implications of radionuclides for ecosystems and human health if nuclear energy is to be used to avoid the impending global energy crisis. The present volume of the EIC Books series addresses this critical need by providing fundamental information on environmentally significant radionuclides. The content of this book was developed in collaboration with many of the authors of the chapters. Given the enormity of the subject the Editor and the Authors had to be judicious in selecting the chapters that would appropriately encompass and describe the primary topics, particularly those that are of importance to the health of ecosystems and humans. The resulting chapters were chosen to provide this information in a book of useful and appropriate length. Each chapter provides fundamental information on the chemistry of the radionuclides, their occurrence and movement in the enivornment, separation and analyses, and the technologies needed for their remediation and mitigation. The chapters are structured with a common, systematic format in order to facilitate comparions between elements and groups of elements. About EIC Books The Encyclopedia of Inorganic Chemistry (EIC) has proved to be one of the defining standards in inorganic chemistry, and most chemistry libraries around the world have access either to the first of second print editon, or to the online version. Many readers, however, prefer to have more concise thematic volumes, targeted to their specific area of interest. This feedback from EIC readers has encouraged the Editors to plan a series of EIC Books, focusing on topics of current interest. They will appear on a regular basis, and will feature leading scholars in their fields. Like the Encyclopedia, EIC Books aims to provide both the starting research student and the confirmed research worker with a critical distillation of the leading concepts in inorganic and bioinorganic chemistry, and provide a structured entry into the fields covered. This volume is also available as part of Encyclopedia of Inorganic Chemistry, 5 Volume Set. This set combines all volumes published as EIC Books from 2007 to 2010, representing areas of key developments in the field of inorganic chemistry published in the Encyclopedia of Inorganic Chemistry. Find out more.
