WorldWideScience

Sample records for atmospheric dispersion model

  1. Improving practical atmospheric dispersion models

    International Nuclear Information System (INIS)

    The new generation of practical atmospheric dispersion model (for short range ≤ 30 km) are based on dispersion science and boundary layer meteorology which have widespread international acceptance. In addition, recent improvements in computer skills and the widespread availability of small powerful computers make it possible to have new regulatory models which are more complex than the previous generation which were based on charts and simple formulae. This paper describes the basis of these models and how they have developed. Such models are needed to satisfy the urgent public demand for sound, justifiable and consistent environmental decisions. For example, it is preferable that the same models are used to simulate dispersion in different industries; in many countries at present different models are used for emissions from nuclear and fossil fuel power stations. The models should not be so simple as to be suspect but neither should they be too complex for widespread use; for example, at public inquiries in Germany, where simple models are mandatory, it is becoming usual to cite the results from highly complex computational models because the simple models are not credible. This paper is written in a schematic style with an emphasis on tables and diagrams. (au) (22 refs.)

  2. Stochastic models for atmospheric dispersion

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2003-01-01

    Simple stochastic differential equation models have been applied by several researchers to describe the dispersion of tracer particles in the planetary atmospheric boundary layer and to form the basis for computer simulations of particle paths. To obtain the drift coefficient, empirical vertical...... variation by height is adopted. A particular problem for simulation studies with finite time steps is the construction of a reflection rule different from the rule of perfect reflection at the boundaries such that the rule complies with the imposed skewness of the velocity distribution for particle...... positions close to the boundaries. Different rules have been suggested in the literature with justifications based on simulation studies. Herein the relevant stochastic differential equation model is formulated in a particular way. The formulation is based on the marginal transformation of the position...

  3. Atmospheric dispersion modeling of radioactive effluents

    International Nuclear Information System (INIS)

    In case of a nuclear accident, which could lead to release of radioactive contaminants, fastest countermeasures are needed, relating to sheltering, iodine distribution, evacuation and interdiction of food and water consumption. All these decisions should be based either on estimation of inhaled dose and the dose due to external exposure for public or on the estimation of radioactive concentration in food (which will depend on the radioactive concentration in air and ground deposition). In order to perform any of these calculations of consequences in case of nuclear accident, which leads to release of radioactive contaminants in the atmosphere, we must start with atmospheric dispersion calculations. In the last few years, considerable efforts have been devoted in order to improve computer codes for dispersion in the atmosphere of the radioactive contaminants released in a nuclear accident. The paper presents the model used in computer codes for assessment of nuclear accident consequences and a special attention was paid to the dispersion model used in the Institute for Nuclear Research Pitesti. The values for the used parameters and the results for air and ground concentration are also presented. (authors)

  4. Aerial Radioactivity Monitoring Using Atmospheric Dispersion Model

    International Nuclear Information System (INIS)

    Since North Korea announced the underground nuclear test on last October 9th, 2006, many countries including South Korea have worried about the atmospheric dispersion and pollution of radioactive material by nuclear test. To verify the existence of nuclear test by detecting radioactive materials such as xenon and krypton at the early stage, to locate the position of test site, and to chase the trajectory of radioactivity have been heavily issued. And radioactivity detection and radiation monitoring technology using an aircraft have been recently examined by an authority concerned in South Korea. Although various techniques of aerial radioactivity monitoring are developed and operated in the world such as United States of America, Japan, Germany, etc., the relevant technical development or research is wholly lacking in our country. In this study, we performed some case studies on North Korea's nuclear test and accidental releases from nuclear power plant (NPP) using HYSPLIT (HYbrid Single Particle Lagrangian Integrated Trajectory) model developed by National Oceanic and Atmospheric Administration (NOAA) of U.S. Department of Commerce. We also investigated a feasibility of HYSPLIT to the aerial radioactivity monitoring system in terms of deciding potential measuring location and time

  5. Accident consequence assessments with different atmospheric dispersion models

    International Nuclear Information System (INIS)

    An essential aim of the improvements of the new program system UFOMOD for Accident Consequence Assessments (ACAs) was to substitute the straight-line Gaussian plume model conventionally used in ACA models by more realistic atmospheric dispersion models. To identify improved models which can be applied in ACA codes and to quantify the implications of different dispersion models on the results of an ACA, probabilistic comparative calculations with different atmospheric dispersion models have been performed. The study showed that there are trajectory models available which can be applied in ACAs and that they provide more realistic results of ACAs than straight-line Gaussian models. This led to a completely novel concept of atmospheric dispersion modelling in which two different distance ranges of validity are distinguished: the near range of some ten kilometres distance and the adjacent far range which are assigned to respective trajectory models. (orig.)

  6. Atmospheric Dispersion Model Validation in Low Wind Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patrick

    2007-11-01

    Atmospheric plume dispersion models are used for a variety of purposes including emergency planning and response to hazardous material releases, determining force protection actions in the event of a Weapons of Mass Destruction (WMD) attack and for locating sources of pollution. This study provides a review of previous studies that examine the accuracy of atmospheric plume dispersion models for chemical releases. It considers the principles used to derive air dispersion plume models and looks at three specific models currently in use: Aerial Location of Hazardous Atmospheres (ALOHA), Emergency Prediction Information Code (EPIcode) and Second Order Closure Integrated Puff (SCIPUFF). Results from this study indicate over-prediction bias by the EPIcode and SCIPUFF models and under-prediction bias by the ALOHA model. The experiment parameters were for near field dispersion (less than 100 meters) in low wind speed conditions (less than 2 meters per second).

  7. Analysis of software for modeling atmospheric dispersion

    International Nuclear Information System (INIS)

    During last few years, a number software packages for microcomputes have appeared with the aim to simulate diffusion of atmospheric pollutants. These codes, simplifying the models used for safety analyses of industrial plants are becoming more useful, and are even used for post-accidental conditions. The report presents for the first time in a critical manner, principal models available up to this date. The problem arises in adapting the models to the demanded post-accidental interventions. In parallel to this action an analysis of performance was performed. It means, identifying the need of forecasting the most appropriate actions to be performed having in mind short available time and lack of information. Because of these difficulties, it is possible to simplify the software, which will not include all the options but could deal with a specific situation. This would enable minimisation of data to be collected on the site

  8. Atmospheric dispersion models for application in relation to radionuclide releases

    International Nuclear Information System (INIS)

    In this document, a state-of-art review of dispersion models relevant to local, regional and global scales and applicable to radionuclide discharges of a continuous and discontinuous nature is presented. The theoretical basis of the models is described in chapter 2, while the uncertainty inherent in model predictions is considered in chapter 6. Chapters 3 to 5 of this report describe a number of models for calculating atmospheric dispersion on local, regional and global scales respectively

  9. Atmospheric dispersion modeling near a roadway under calm meteorological conditions

    OpenAIRE

    Fallah Shorshani, Masoud; Seigneur, Christian; POLO REHN, Lucie; CHANUT, Hervé; PELLAN, Yann; Jaffrezo, Jean-Luc; CHARRON, Aurélie; Andre, Michel

    2015-01-01

    Atmospheric pollutant dispersion near sources is typically simulated by Gaussian models because of their efficient compromise between reasonable accuracy and manageable com- putational time. However, the standard Gaussian dispersion formula applies downwind of a source under advective conditions with a well-defined wind direction and cannot calculate air pollutant concentrations under calm conditions with fluctuating wind direction and/or upwind of the emission source. Attempts have been made...

  10. Optimizing the calculation grid for atmospheric dispersion modelling

    International Nuclear Information System (INIS)

    This paper presents three approaches to find optimized grids for atmospheric dispersion measurements and calculations in emergency planning. This can be useful for deriving optimal positions for mobile monitoring stations, or help to reduce discretization errors and improve recommendations. Indeed, threshold-based recommendations or conclusions may differ strongly on the shape and size of the grid on which atmospheric dispersion measurements or calculations of pollutants are based. Therefore, relatively sparse grids that retain as much information as possible, are required. The grid optimization procedure proposed here is first demonstrated with a simple Gaussian plume model as adopted in atmospheric dispersion calculations, which provides fast calculations. The optimized grids are compared to the Noodplan grid, currently used for emergency planning in Belgium, and to the exact solution. We then demonstrate how it can be used in more realistic dispersion models. - Highlights: • Grid points for atmospheric dispersion calculations are optimized. • Using heuristics the optimization problem results into different grid shapes. • Comparison between optimized models and the Noodplan grid is performed

  11. Complex source rate estimation for atmospheric transport and dispersion models

    International Nuclear Information System (INIS)

    The accuracy associated with assessing the environmental consequences of an accidental atmospheric release of radioactivity is highly dependent on our knowledge of the source release rate which is generally poorly known. This paper reports on a technique that integrates the radiological measurements with atmospheric dispersion modeling for more accurate source term estimation. We construct a minimum least squares methodology for solving the inverse problem with no a priori information about the source rate

  12. Comparative calculations and validation studies with atmospheric dispersion models

    International Nuclear Information System (INIS)

    This report presents the results of an intercomparison of different mesoscale dispersion models and measured data of tracer experiments. The types of models taking part in the intercomparison are Gaussian-type, numerical Eulerian, and Lagrangian dispersion models. They are suited for the calculation of the atmospherical transport of radionuclides released from a nuclear installation. For the model intercomparison artificial meteorological situations were defined and corresponding arithmetical problems were formulated. For the purpose of model validation real dispersion situations of tracer experiments were used as input data for model calculations; in these cases calculated and measured time-integrated concentrations close to the ground are compared. Finally a valuation of the models concerning their efficiency in solving the problems is carried out by the aid of objective methods. (orig./HP)

  13. Evaluation of atmospheric dispersion/consequence models supporting safety analysis

    International Nuclear Information System (INIS)

    Two DOE Working Groups have completed evaluation of accident phenomenology and consequence methodologies used to support DOE facility safety documentation. The independent evaluations each concluded that no one computer model adequately addresses all accident and atmospheric release conditions. MACCS2, MATHEW/ADPIC, TRAC RA/HA, and COSYMA are adequate for most radiological dispersion and consequence needs. ALOHA, DEGADIS, HGSYSTEM, TSCREEN, and SLAB are recommended for chemical dispersion and consequence applications. Additional work is suggested, principally in evaluation of new models, targeting certain models for continued development, training, and establishing a Web page for guidance to safety analysts

  14. Development of web-based environment for atmospheric dispersion modeling

    Czech Academy of Sciences Publication Activity Database

    Hofman, Radek; Pecha, Petr

    La Garde Park, Illinois, USA : American Nuclear Society, 2013. ISBN 978-0-89448-702-6. [International Topical Meeting on Probabilistic Safety Assessment and Analysis . Columbia, SC (US), 22.09.2013-27.09.2013] R&D Projects: GA MV(CZ) VG20102013018 Institutional support: RVO:67985556 Keywords : distributed computing * atmoshepric dispersion * web environment Subject RIV: DL - Nuclear Waste, Radioactive Pollution ; Quality http://library.utia.cas.cz/separaty/2013/AS/hofman-development of web -based environment for atmospheric dispersion modeling.pdf

  15. A Real-Time Atmospheric Dispersion Modeling System

    International Nuclear Information System (INIS)

    This paper describes a new 3-D multi-scale atmospheric dispersion modeling system and its on-going evaluation. This system is being developed for both real-time operational applications and detailed assessments of events involving atmospheric releases of hazardous material. It is part of a new, modernized Department of Energy (DOE) National Atmospheric Release Advisory Center (NARAC) emergency response computer system at Lawrence Livermore National Laboratory. This system contains coupled meteorological data assimilation and dispersion models, initial versions of which were described by Sugiyama and Chan (1998) and Leone et al. (1997). Section 2 describes the current versions of these models, emphasizing new features. This modeling system supports cases involving both simple and complex terrain, and multiple space and time scales from the microscale to mesoscale. Therefore, several levels of verification and evaluation are required. The meteorological data assimilation and interpolation algorithms have been previously evaluated by comparison to observational data (Sugiyama and Chan, 1998). The non-divergence adjustment algorithm was tested against potential flow solutions and wind tunnel data (Chan and Sugiyama, 1997). Initial dispersion model results for a field experiment case study were shown by Leone et al. (1997). A study in which an early, prototype version of the new modeling system was evaluated and compared to the current NARAC operational models showed that the new system provides improved results (Foster et al., 1999). In Section 3, we show example results from the current versions of the models, including verification using analytic solutions to the advection-diffusion equation as well as on-going evaluation using microscale and mesoscale dispersion field experiments

  16. Atmospheric dispersion modeling: Challenges of the Fukushima Daiichi response

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Gayle [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pobanz, Brenda [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Foster, Kevin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vogt, Phil [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Aluzzi, Fernando [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homann, Steve [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-05-01

    In this research, the U.S. Department of Energy’s (DOE) National Atmospheric Release Advisory Center (NARAC) provided a wide range of predictions and analyses as part of the response to the Fukushima Daiichi Nuclear Power Plant accident including: daily Japanese weather forecasts and atmospheric transport predictions to inform planning for field monitoring operations and to provide U.S. government agencies with ongoing situational awareness of meteorological conditions; estimates of possible dose in Japan based on hypothetical U.S. Nuclear Regulatory Commission scenarios of potential radionuclide releases to support protective action planning for U.S. citizens; predictions of possible plume arrival times and dose levels at U.S. locations; and source estimation and plume model refinement based on atmospheric dispersion modeling and available monitoring data.

  17. The improved sequential puff model for atmospheric dispersion evaluation (SPADE)

    International Nuclear Information System (INIS)

    The present report describes the improved version of the Sequential Puff for Atmospheric Dispersion Evaluation Model (SPADE), developed at EKEA-DISP as a component of ARIES (Atmospheric Release Impact Evaluation System). SPADE has been originally designed for real time assessment of the consequences of a nuclear release into the atmosphere, but it is also suited for sensitivity studies, investigations, or routine applications. It can estimate ground-level air concentrations, deposition and cloud γ dose rate in flat or gently rolling terrain in the vicinity of a point source. During the last years several aspects of the modelling of dispersion processes have been improved, and new modules have been implemented in SPADE. In the first part of the report, a general description of the model is given, and the assumptions and parameterizations used to simulate the main physical processes are described. The second part concerns with the structure of the computer code and of input and output files, and can be regarded as a user's guide to the model. (author)

  18. Meteorological Uncertainty of atmospheric Dispersion model results (MUD)

    DEFF Research Database (Denmark)

    Havskov Sørensen, Jens; Amstrup, Bjarne; Feddersen, Henrik;

    uncertainties of the meteorological model results. These uncertainties stem from e.g. limits in meteorological observations used to initialise meteorological forecast series. By perturbing e.g. the initial state of an NWP model run in agreement with the available observational data, an ensemble of...... meteorological forecasts is produced from which uncertainties in the various meteorological parameters are estimated, e.g. probabilities for rain. Corresponding ensembles of atmospheric dispersion can now be computed from which uncertainties of predicted radionuclide concentration and deposition patterns can be...

  19. A comparison of models fos dispersion of atmospheric contaminants

    International Nuclear Information System (INIS)

    In this work a stack emission in actual atmospheric conditions was modeled with AERMOD, HPDM, PCCOSYMA and HYSPLIT codes. The first two have Gaussian stationary plume models and they were developed to calculate environmental impact produced by chemical contaminants. PCCOSYMA has a Gaussian-type segmented plume model, developed for assessing radiological impact of nuclear accidents. HYSPLIT has a hybrid code that uses a Lagrangian reference system to describe the transport of a puff mass center and an Eulerian system to describe the dispersion within the puff. The emission was fixed in 0.3 g.s-1, 284 K and 0 m.s-1, that is in equilibrium with the environment, in order to compare the different codes results. Flat terrain with fixed 0.1 m surface rough was considered. Meteorological and topographic data used were obtained from runs of the prognostic code RAMS, provided by NOAA. The main contribution of this work is to provide recommendations about the validity range of each code depending on the model used. For Gaussian models the distance in which the atmospheric condition can be considered homogeneous determines the validity range. On the other hand the validity range of HYSPLIT model is determined by the availability of the meteorological data spatial extension. There was a significant difference between the dispersion parameters used by the Gaussian codes. (author)

  20. The Atmospheric Radionuclide Transport Model (ARTM) - Validation of a long-term atmospheric dispersion model

    Science.gov (United States)

    Hettrich, Sebastian; Wildermuth, Hans; Strobl, Christopher; Wenig, Mark

    2016-04-01

    In the last couple of years, the Atmospheric Radionuclide Transport Model (ARTM) has been developed by the German Federal Office for Radiation Protection (BfS) and the Society for Plant and Reactor Security (GRS). ARTM is an atmospheric dispersion model for continuous long-term releases of radionuclides into the atmosphere, based on the Lagrangian particle model. This model, developed in the first place as a more realistic replacement for the out-dated Gaussian plume models, is currently being optimised for further scientific purposes to study atmospheric dispersion in short-range scenarios. It includes a diagnostic wind field model, allows for the application of building structures and multiple sources (including linear, 2-and 3-dimensional source geometries), and considers orography and surface roughness. As an output it calculates the activity concentration, dry and wet deposition and can model also the radioactive decay of Rn-222. As such, ARTM requires to undergo an intense validation process. While for short-term and short-range models, which were mainly developed for examining nuclear accidents or explosions, a few measurement data-sets are available for validation, data-sets for validating long-term models are very sparse and the existing ones mostly prove to be not applicable for validation. Here we present a strategy for the validation of long-term Lagrangian particle models based on the work with ARTM. In our validation study, the first part we present is a comprehensive analysis of the model sensitivities on different parameters like e.g. (simulation grid size resolution, starting random number, amount of simulation particles, etc.). This study provides a good estimation for the uncertainties of the simulation results and consequently can be used to generate model outputs comparable to the available measurements data at various distances from the emission source. This comparison between measurement data from selected scenarios and simulation results

  1. Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

    Directory of Open Access Journals (Sweden)

    Khandakar Md Habib Al Razi, Moritomi Hiroshi, Kambara Shinji

    2012-01-01

    Full Text Available The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environmental concern. Identification of sources contributing to the high atmospheric mercury levels will be useful for formulating pollution control and mitigation strategies in the region. In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of "Substances Requiring Priority Action" published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 μg/m3. Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER that estimates regional atmospheric concentration and distribution. The second is the Hybrid Single Particle Lagrangian Integrated trajectory Model (HYSPLIT that estimates the

  2. CRUNCH, Dispersion Model for Continuous Dense Vapour Release in Atmosphere

    International Nuclear Information System (INIS)

    ambient atmospheric turbulence, and to follow the dispersion processes down to low concentrations, especially important for toxic gases, a virtual source passive dispersion model is fitted to the slumping plume. 2 - Restrictions on the complexity of the problem: Acceleration of the plume to the wind velocity is not considered, since an analysis of inertial effects has shown that the time for which these are important is short, compared to the dispersion time. Additionally, wind shear effects on cloud structure are not included; for a puff release producing a cloud of finite extent, this may not be valid but for a plume, extending to large downwind distances, they can be argued to have only a minor influence at the advancing front

  3. Atmospheric dispersion models help to improve air quality; Los modelos de dispersion atmosferica ayudan a mejorar la calidad del aire

    Energy Technology Data Exchange (ETDEWEB)

    Martin, F.

    2013-07-01

    One of the main challenges of the atmospheric sciences is to reproduce as well as possible the phenomena and processes of pollutants in the atmosphere. To do it, mathematical models based in this case on fluid dynamics and mass and energy conservation equations, equations that govern the atmospheric chemistry, etc., adapted to the spatial scales to be simulated, are developed. The dispersion models simulate the processes of transport, dispersion, chemical transformation and elimination by deposition that air pollutants undergo once they are emitted. Atmospheric dispersion models with their multiple applications have become essential tools for the air quality management. (Author)

  4. Global atmospheric dispersion modelling after the Fukushima accident

    Energy Technology Data Exchange (ETDEWEB)

    Suh, K.S.; Youm, M.K.; Lee, B.G.; Min, B.I. [Korea Atomic Energy Research Institute (Korea, Republic of); Raul, P. [Universidad de Sevilla (Spain)

    2014-07-01

    A large amount of radioactive material was released to the atmosphere due to the Fukushima nuclear accident in March 2011. The radioactive materials released into the atmosphere were mostly transported to the Pacific Ocean, but some of them were fallen on the surface due to dry and wet depositions in the northwest area from the Fukushima nuclear site. Therefore, northwest part of the nuclear site was seriously contaminated and it was designated with the restricted zone within a radius of 20 ∼ 30 km around the Fukushima nuclear site. In the early phase of the accident from 11 March to 30 March, the radioactive materials were dispersed to an area of the inland and offshore of the nuclear site by the variations of the wind. After the Fukushima accident, the radionuclides were detected through the air monitoring in the many places over the world. The radioactive plume was transported to the east part off the site by the westerly jet stream. It had detected in the North America during March 17-21, in European countries during March 23-24, and in Asia during from March 24 to April 6, 2011. The radioactive materials were overall detected across the northern hemisphere passed by 15 ∼ 20 days after the accident. Three dimensional numerical model was applied to evaluate the dispersion characteristics of the radionuclides released into the air. Simulated results were compared with measurements in many places over the world. Comparative results had good agreements in some places, but they had a little differences in some locations. The difference between the calculations and measurements are due to the meteorological data and relatively coarse resolutions in the model. Some radioactive materials were measured in Philippines, Taiwan, Hon Kong and South Korea during from March 23-28. It inferred that it was directly transported from the Fukushima by the northeastern monsoon winds. This event was well represented in the numerical model. Generally, the simulations had a good

  5. A model for long range atmospheric dispersion of radionuclides released over a short period

    International Nuclear Information System (INIS)

    This report is the fourth in a series which gives practical guidance on the estimation of the dispersion of radioactive material released to the atmosphere. It represents the conclusions of a Working Group established to review recent developments in atmospheric dispersion modelling and to propose models for use within the UK. This report describes a model considered suitable for calculating dispersion at long range from releases of short duration. (author)

  6. Atmospheric dispersion modelling over complex terrain at small scale

    Czech Academy of Sciences Publication Activity Database

    Nosek, Štěpán; Jaňour, Zbyněk; Kukačka, Libor; Jurčáková, Klára

    Kutná Hora: E D P Sciences, 2014 - (Vít, T.; Dančová, P.; Novotný, P.). (EPJ Web of Conferences. 67). ISBN 978-80-260-5375-0. ISSN 2101-6275. [Experimental Fluid Mechanics 2013. Kutná Hora (CZ), 19.11.2013-22.11.2013] R&D Projects: GA TA ČR TA01020428 Institutional support: RVO:61388998 Keywords : wind-tunnel * atmospheric dispersion * coal dust * air pollution * complex terrain Subject RIV: DG - Athmosphere Sciences, Meteorology

  7. Modelling of pollution dispersion in atmosphere; Modelowanie procesow propagacji skazen w atmosferze

    Energy Technology Data Exchange (ETDEWEB)

    Borysiewicz, M.; Stankiewicz, R.

    1994-12-31

    The paper contains the review of the mathematical foundation of atmospheric dispersion models. The atmospheric phenomena relevant to atmospheric dispersion model are discussed. In particular the parametrization of processes with time and space scales smaller than numerical grid size, limited by available computer power, is presented. The special attention was devoted to similarity theory and parametrization of boundary layer. The numerical methods are analysed and the drawbacks of the method are presented. (author). 99 refs, 15 figs, 3 tabs.

  8. A comparison of Gaussian and diffusivity models of atmospheric dispersion

    International Nuclear Information System (INIS)

    The Gaussian plume diffusion model of Smith and a diffusivity model by Maul are compared over the full range of atmospheric stability. The models' predictions for ground level concentration are found to agree well a) for ground level releases of materials, and b) for elevated releases of material at distances comparable to or greater than the distance of maximum ground level concentration. Surface layer, ground roughness, and dry deposition effects are examined and a simple ground deposition model used in the Gaussian plume model is found to be adequate over most of the stability range. Uncertainties due to the models themselves and the meteorological input data are estimated and the advantages and limitations of both types of model are discussed. It is concluded that the models are suitable for a variety of applications and that they are fast and inexpensive to run as computer models. (author)

  9. AERAD, the atmospheric dispersion model for emergency response at the Whiteshell Laboratories, Manitoba, Canada

    International Nuclear Information System (INIS)

    The Whiteshell Laboratories atmospheric dispersion model, AERAD, which would be used in the case of an accidental atmospheric release of radioactivity, is described. We outline the potential source terms at the Whiteshell site and the methodology used to calculate atmospheric concentrations and radiological doses to humans. (author). 26 refs., 6 tabs., 4 figs

  10. Sea breeze wind field prediction in atmospheric dispersion modelling

    International Nuclear Information System (INIS)

    The estimation of the dispersion of an airborne radioactive release presupposes the knowledge of the windfield and the level of diffusion in the region under consideration. The presence of the sea breeze requires particular attention due to the development of circulation patterns and reduced mixing depths within the boundary layer. The present work constitutes a part of the effort to include the sea breeze capability in the ADREA-I code, a transient three dimensional transport code, and refers specifically to the sea breeze analysis along the Alaskan sea coast. It is shown that the generalized three dimensional k-1 model introduced in ADREA-I, can be also faithfully applied to sea breeze calculations. (author)

  11. Atmospheric Prognostic and Dispersion Model Design for use in the European Ensemble Modeling Exercises

    International Nuclear Information System (INIS)

    The Savannah River Technology Center (SRTC) of the Department of Energy (DOE)Savannah River Site (SRS) has been involved with predicting the transport and dispersion of hazardous atmospheric releases for many years. The SRS utilizes an automated, real-time capability for consequence assessment during emergency response to local releases. The emphasis during these situations is to provide accurate guidance as quickly as possible. Consequently, atmospheric transport and dispersion models of a simple physical nature (such as Gaussian plume models) have typically been used in an effort to provide timely responses. However, use of one or two-dimensional (steady-state) winds are inadequate in conditions of high spatial and temporal variability (such as during frontal passage). Increased computing capabilities have led to the use of more sophisticated three dimensional prognostic models that may capture some of these higher resolution phenomena. In an ideal situation, the decision-maker would want to use the best model each time an accident occurred. Unfortunately, due to the nonunique nature of solutions to the nonlinear equations governing the atmosphere, model A may perform better than models B and C in one type of weather scenario, and worse during a different situation.Therefore, it is not always possible to distinguish which model is best, especially during a forecast situation. The use of an ensemble approach of averaging results from a variety of model solutions is beneficial to the modeler in providing the DM guidance on model uncertainties. Meteorological forecasts generated by numerical models provide individual realizations of the atmosphere. The resulting wind and turbulence fields are then used to drive atmospheric dispersion (transport and diffusion) models. Although many modeling agencies utilize ensemble-modeling techniques to determine atmospheric model sensitivities of prognostic fields (i.e. wind, temperature, radiation, etc.), the European Union has

  12. Modelling the atmospheric dispersion of foot-and-mouth disease virus for emergency preparedness

    DEFF Research Database (Denmark)

    Sørensen, J.H.; Jensen, C.O.; Mikkelsen, T.;

    2001-01-01

    A model system for simulating airborne spread of foot-and-mouth disease (FMD) is described. The system includes a virus production model and the local- and mesoscale atmospheric dispersion model RIMPUFF linked to the LINCOM local-scale Row model. LINCOM is used to calculate the sub-grid scale Row...

  13. Modelling and tracer studies of atmospheric dispersion and deposition in regions of complex topography

    International Nuclear Information System (INIS)

    An indium tracer aerosol generating apparatus based on an alcohol/oxygen burner, and an analytical procedure by which filter samples containing tracer material could be analysed quantitatively by means of neutron activation analysis, were developed for use in atmospheric dispersion and deposition studies. A number of series of atmospheric dispersion experiments were conducted in the Richards Bay and Koeberg- Cape Town areas. The results are given, comparing the airbone tracer concentrations measured at ground level with values predicted by means of a numerical model, utilising two to three schemes, varying in sophistication, for calculating the dispersion coefficients. Recommendations are given regarding a dispersion model and dispersion coefficients for regular use in the Koeberg area, and ways for estimating plume trajectories

  14. Modeling of mesoscale atmospheric dispersion of radioactive materials released from nuclear power plants in coastal regions

    International Nuclear Information System (INIS)

    A Lagrangian atmospheric dispersion model combining a three dimensional prognostic sea-land breeze model has been developed and applied to the analysis of mesoscale atmospheric dispersion of radiological releases from the nuclear power plants in mountainous coastal regions. The basic formula in the sea-land breeze model was hydrostatic primitive equations in the terrain-following coordinate. In the mesoscale atmospheric dispersion model a Markov chain process and a kernel density estimator were adopted. In this study, the mesoscale atmospheric circulation and particle dispersion simulations around the Wolsung nuclear power site located near east coastline of Korea were carried out by using the developed models under two synoptic weather conditions on a clear day in summer. The results showed that atmospheric dispersions were affected by wind directions of sea breeze and land breeze according to synoptic weather conditions. In the case of the northerly synoptic wind condition, the radioactive particles released during the day were transported northwestward by sea breezes (southeasterly) and recirculated southeastward to the Wolsung site by land breezes (Northwesterly) at night. In the case of the weak southerly synoptic wind condition, however, the recirculation of particles by wind direction change by sea breeze and land breeze were not induced since sea breeze and land breeze all were southerly flows. In further study, mesoscale atmospheric dispersions according to all synoptic weather condition classified by wind direction, wind speed and could coverage will be calculated by using the developed model. Eventually, the off-site public dose around the Wolsung site will be evaluated in consideration of local atmospheric circulations. (author). 13 refs., 1 tab., 4 figs

  15. Numerical models for computation of pollutant-dispersion in the atmosphere

    International Nuclear Information System (INIS)

    The report describes some models which are used to compute the concentration of emitted pollutants in the lower atmosphere. A dispersion model, developed at the University of Hamburg, is considered in more detail and treated with two different numerical methods. The convergence of the methods is investigated and a comparison of numerical results and dispersion experiments carried out at the Nuclear Research Center Karlsruhe is given. (orig.)

  16. Modeling of the chemical behavior of sodium fire aerosols during atmospheric dispersion

    International Nuclear Information System (INIS)

    Conclusions: • Development of a preliminary kinetic model of NaOH aerosols carbonation based on the shrinking core model for chemical and physical evolutions with transfer time during atmospheric dispersion -> These kinetic models can be implemented in atmospheric dispersion code to calculate mass concentration evolution of each compound. • Validation of kinetic control by internal diffusion of CO2 into solid Na2CO3 external layer by non-dimensional criteria analysis. • First validation of theoretical calculations with available experimental results -> correct results for small aerosols sizes (< 1 μm) but further improvements and validations are required to describe larger particles behavior

  17. Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

    OpenAIRE

    Khandakar Md Habib Al Razi, Moritomi Hiroshi, Kambara Shinji

    2012-01-01

    The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environm...

  18. Atmospheric aerosol dispersion models and their applications to environmental risk assessment

    Directory of Open Access Journals (Sweden)

    Andrzej Mazur

    2014-03-01

    Full Text Available Introduction. Numerical models of dispersion of atmospheric pollutants are widely used to forecast the spread of contaminants in the air and to analyze the effects of this phenomenon. The aim of the study is to investigate the possibilities and the quality of diagnosis and prediction of atmospheric transport of aerosols in the air using the dispersion model of atmospheric pollutants, developed at the Institute of Meteorology and Water Management (IMWM in Warsaw. Material and methods. A model of the dispersion of atmospheric pollutants, linked with meteorological models in a diagnostic mode, was used to simulate the transport of the cloud of aerosols released during the crash near the town of Ożydiw (Ukraine and of volcanic ash – during the volcanic eruption of Eyjafjallajökull in Iceland. Results. Possible directions of dispersion of pollutants in the air and its concentration in the atmosphere and deposition to the soil were assessed. The analysis of temporal variability of concentrations of aerosols in the atmosphere confirmed that the model developed at IMWM is an effective tool for diagnosis of air quality in the area of Poland as well as for determination of exposure duration to the aerosol clouds for different weather scenarios. Conclusions. The results are a confirmation of the thesis, that because in the environmental risk assessment, an important element is not only current information on the level of pollution concentrations, but also the time of exposure to pollution and forecast of these elements, and consequently the predicted effects on man or the environment in general; so it is necessary to use forecasting tools, similar to presented application. The dispersion model described in the paper is an operational tool for description, analysis and forecasting of emergency situations in case of emissions of hazardous substances.

  19. Atmospheric Dispersion Simulation for Level 3 PSA at Ulchin Nuclear Site using a PUFF model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jun; Han, Seok-Jung; Jeong, Hyojoon; Jang, Seung-Cheol [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    Air dispersion prediction is a key in the level 3 PSA to predict radiation releases into the environment for preparing an effective strategy for an evacuation as a basis of the emergency preparedness. To predict the atmospheric dispersion accurately, the specific conditions of the radiation release location should be considered. There are various level 3 PSA tools and MACSS2 is one of the widely used level 3 PSA tools in many countries including Korea. Due to the characteristics of environmental conditions in Korea, it should be demonstrated that environmental conditions of Korea nuclear sites can be appropriately illustrated by the tool. In Korea, because all nuclear power plants are located on coasts, sea and land breezes might be a significant factor. The objectives of this work is to simulate the atmospheric dispersion for Ulchin nuclear site in Korea using a PUFF model and to generate the data which can be used for the comparison with that of PLUME model. A nuclear site has own atmospheric dispersion characteristics. Especially in Korea, nuclear sites are located at coasts and it is expected that see and land breeze effects are relatively high. In this work, the atmospheric dispersion at Ulchin nuclear site was simulated to evaluate the effect of see and land breezes in four seasons. In the simulation results, it was observed that the wind direction change with time has a large effect on atmospheric dispersion. If the result of a PLUME model is more conservative than most severe case of a PUFF model, then the PLUME model could be used for Korea nuclear sites in terms of safety assessment.

  20. Atmospheric Dispersion Simulation for Level 3 PSA at Ulchin Nuclear Site using a PUFF model

    International Nuclear Information System (INIS)

    Air dispersion prediction is a key in the level 3 PSA to predict radiation releases into the environment for preparing an effective strategy for an evacuation as a basis of the emergency preparedness. To predict the atmospheric dispersion accurately, the specific conditions of the radiation release location should be considered. There are various level 3 PSA tools and MACSS2 is one of the widely used level 3 PSA tools in many countries including Korea. Due to the characteristics of environmental conditions in Korea, it should be demonstrated that environmental conditions of Korea nuclear sites can be appropriately illustrated by the tool. In Korea, because all nuclear power plants are located on coasts, sea and land breezes might be a significant factor. The objectives of this work is to simulate the atmospheric dispersion for Ulchin nuclear site in Korea using a PUFF model and to generate the data which can be used for the comparison with that of PLUME model. A nuclear site has own atmospheric dispersion characteristics. Especially in Korea, nuclear sites are located at coasts and it is expected that see and land breeze effects are relatively high. In this work, the atmospheric dispersion at Ulchin nuclear site was simulated to evaluate the effect of see and land breezes in four seasons. In the simulation results, it was observed that the wind direction change with time has a large effect on atmospheric dispersion. If the result of a PLUME model is more conservative than most severe case of a PUFF model, then the PLUME model could be used for Korea nuclear sites in terms of safety assessment

  1. Meteorological Uncertainty of atmospheric Dispersion model results (MUD)

    DEFF Research Database (Denmark)

    Havskov Sørensen, Jens; Amstrup, Bjarne; Feddersen, Henrik;

    meteorological model results. These uncertainties stem from e.g. limits in meteorological obser-vations used to initialise meteorological forecast series. By perturbing the initial state of an NWP model run in agreement with the available observa-tional data, an ensemble of meteorological forecasts is produced...

  2. Objectives for next generation of practical short-range atmospheric dispersion models

    International Nuclear Information System (INIS)

    The proceedings contains papers from the workshop ''Objectives for Next Generation of Practical Short-Range Atmospheric Dispersion Models''. They deal with two types of models, namely models for regulatory purposes and models for real-time applications. The workshop was the result of an action started in 1991 for increased cooperation and harmonization within atmospheric dispersion modelling. The focus of the workshop was on the management of model development and the definition of model objectives, rather than on detailed model contents. It was the intention to identify actions that can be taken in order to improve the development and use of atmospheric dispersion models. The papers in the proceedings deal with various topics within the broad spectrum of matters related to up-to-date practical models, such as their scientific basis, requirements for model input and output, meteorological preprocessing, standardisation within modelling, electronic information exchange as a potentially useful tool, model evaluation and data bases for model evaluation. In addition to the papers, the proceedings contain summaries of the discussions at the workshop. These summaries point to a number of recommended actions which can be taken in order to improve ''modelling culture''. (AB)

  3. System design for a real-time atmospheric dispersion model

    International Nuclear Information System (INIS)

    An interactive, real-time simulation model has been commissioned at the Koeberg nuclear power station near Cape Town. Use of sheared puffs, solved using only the C00, C01, C10, C02, C20 and C11 horizontal moments, reduced computation and allowed arbitrary variation of the wind vector with height. Wind profiles and diffusivity were given spatial definition about the coastal interface by interpolation between six telemetered mast locations within 20 km of Koeberg. Specific design for a real-time environment revealed important principles concerning division into asynchronous tasks, protection against data failures, and on-line operation interaction. With a grid resolution of 300 m in a 40 km x 40 km map area, the model runs at least three times faster than real-time on a HP3000 minicomputer. (author)

  4. Using meteorological ensembles for atmospheric dispersion modelling of the Fukushima nuclear accident

    Science.gov (United States)

    Périllat, Raphaël; Korsakissok, Irène; Mallet, Vivien; Mathieu, Anne; Sekiyama, Thomas; Didier, Damien; Kajino, Mizuo; Igarashi, Yasuhito; Adachi, Kouji

    2016-04-01

    Dispersion models are used in response to an accidental release of radionuclides of the atmosphere, to infer mitigation actions, and complement field measurements for the assessment of short and long term environmental and sanitary impacts. However, the predictions of these models are subject to important uncertainties, especially due to input data, such as meteorological fields or source term. This is still the case more than four years after the Fukushima disaster (Korsakissok et al., 2012, Girard et al., 2014). In the framework of the SAKURA project, an MRI-IRSN collaboration, a meteorological ensemble of 20 members designed by MRI (Sekiyama et al. 2013) was used with IRSN's atmospheric dispersion models. Another ensemble, retrieved from ECMWF and comprising 50 members, was also used for comparison. The MRI ensemble is 3-hour assimilated, with a 3-kilometers resolution, designed to reduce the meteorological uncertainty in the Fukushima case. The ECMWF is a 24-hour forecast with a coarser grid, representative of the uncertainty of the data available in a crisis context. First, it was necessary to assess the quality of the ensembles for our purpose, to ensure that their spread was representative of the uncertainty of meteorological fields. Using meteorological observations allowed characterizing the ensembles' spread, with tools such as Talagrand diagrams. Then, the uncertainty was propagated through atmospheric dispersion models. The underlying question is whether the output spread is larger than the input spread, that is, whether small uncertainties in meteorological fields can produce large differences in atmospheric dispersion results. Here again, the use of field observations was crucial, in order to characterize the spread of the ensemble of atmospheric dispersion simulations. In the case of the Fukushima accident, gamma dose rates, air activities and deposition data were available. Based on these data, selection criteria for the ensemble members were

  5. Forecasting the consequences of accidental releases of radionuclides in the atmosphere from ensemble dispersion modelling

    International Nuclear Information System (INIS)

    The RTMOD system is presented as a tool for the intercomparison of long-range dispersion models as well as a system for support of decision making. RTMOD is an internet-based procedure that collects the results of more than 20 models used around the world to predict the transport and deposition of radioactive releases in the atmosphere. It allows the real-time acquisition of model results and their intercomparison. Taking advantage of the availability of several model results, the system can also be used as a tool to support decision making in case of emergency. The new concept of ensemble dispersion modelling is introduced which is the basis for the decision-making application of RTMOD. New statistical parameters are presented that allow gathering the results of several models to produce a single dispersion forecast. The devised parameters are presented and tested on the results of RTMOD exercises

  6. Some puff modelling principles relevant for dispersion calculations in the atmosphere

    International Nuclear Information System (INIS)

    Some basic principles for a computational puff-model for prediction and simulation of atmospheric dispersion are discussed. The constraints imposed by use of a single point measurement of the windfield for advection of puffs are examined. A simple scheme for simulation of a more realistic windfield is proposed. One example of the use of a puff-model is shown and comparison is made with an ordinary Gaussian plume model. (author)

  7. UK-ADMS - a new approach to modelling dispersion in the earth's atmospheric boundary layer

    International Nuclear Information System (INIS)

    The UK Atmospheric Dispersion Modelling System is described in considerable detail. The principle modules are dealt with. A key to the methodology is that vertical profiles of mean velocity, temperature and turbulence in the boundary layer depend on the relative values of the height above the ground, the height of the boundary layer, and a length scale determined by the friction velocity and the heat flux and air temperature at the surface. The models can be used at any location. (AB) (15 refs.)

  8. Atmospheric transport and dispersion modeling for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Radiation doses that may have resulted from operations at the Hanford Site are being estimated in the Hanford Environmental Dose Reconstruction (HEDR) Project. One of the project subtasks, atmospheric transport, is responsible for estimating the transport, diffusion and deposition of radionuclides released to the atmosphere. This report discusses modeling transport and diffusion in the atmospheric pathway. It is divided into three major sections. The first section of the report presents the atmospheric modeling approach selected following discussion with the Technical Steering Panel that directs the HEDR Project. In addition, the section discusses the selection of the MESOI/MESORAD suite of atmospheric dispersion models that form the basis for initial calculations and future model development. The second section of the report describes alternative modeling approaches that were considered. Emphasis is placed on the family of plume and puff models that are based on Gaussian solution to the diffusion equations. The final portion of the section describes the performance of various models. The third section of the report discusses factors that bear on the selection of an atmospheric transport modeling approach for HEDR. These factors, which include the physical setting of the Hanford Site and the available meteorological data, serve as constraints on model selection. Five appendices are included in the report. 39 refs., 4 figs., 2 tabs

  9. Description and validation of ERAD: An atmospheric dispersion model for high explosive detonations

    Energy Technology Data Exchange (ETDEWEB)

    Boughton, B.A.; DeLaurentis, J.M.

    1992-10-01

    The Explosive Release Atmospheric Dispersion (ERAD) model is a three-dimensional numerical simulation of turbulent atmospheric transport and diffusion. An integral plume rise technique is used to provide a description of the physical and thermodynamic properties of the cloud of warm gases formed when the explosive detonates. Particle dispersion is treated as a stochastic process which is simulated using a discrete time Lagrangian Monte Carlo method. The stochastic process approach permits a more fundamental treatment of buoyancy effects, calm winds and spatial variations in meteorological conditions. Computational requirements of the three-dimensional simulation are substantially reduced by using a conceptualization in which each Monte Carlo particle represents a small puff that spreads according to a Gaussian law in the horizontal directions. ERAD was evaluated against dosage and deposition measurements obtained during Operation Roller Coaster. The predicted contour areas average within about 50% of the observations. The validation results confirm the model`s representation of the physical processes.

  10. A new formulation of the probability density function in random walk models for atmospheric dispersion

    DEFF Research Database (Denmark)

    Falk, Anne Katrine Vinther; Gryning, Sven-Erik

    In this model for atmospheric dispersion particles are simulated by the Langevin Equation, which is a stochastic differential equation. It uses the probability density function (PDF) of the vertical velocity fluctuations as input. The PDF is constructed as an expansion after Hermite polynomials. In...... several previous works where the PDF was expressed this way, further use was hampered by the fact that the PDF takes negative values for a range of velocities. This problem is overcome in the present formulation...

  11. A model for short and medium range dispersion of radionuclides released to the atmosphere

    International Nuclear Information System (INIS)

    A Working Group was established to give practical guidance on the estimation of the dispersion of radioactive releases to the atmosphere. The dispersion is estimated in the short and medium range, that is from about 100 m to a few tens of kilometres from the source, and is based upon a Gaussian plume model. A scheme is presented for categorising atmospheric conditions and values of the associated dispersion parameters are given. Typical results are presented for releases in specific meteorological conditions and a scheme is included to allow for durations of release of up to 24 hours. Consideration has also been given to predicting longer term average concentrations, typically annual averages, and results are presented which facilitate site specific calculations. The results of the models are extended to 100 km from the source, but the increasing uncertainty with which results may be predicted beyond a few tens of kilometres from the source is emphasised. Three technical appendices provide some of the rationale behind the decisions made in adopting the various models in the proposed dispersion scheme. (author)

  12. Harmonisation within atmospheric dispersion modelling for regulatory purposes. Proceedings. Vol. 2

    International Nuclear Information System (INIS)

    Dispersion modelling has proved to be a very effective tool to assess the environmental impact of human activities on air quality already at the early planning stage. Environmental assessments during planning are required by the EU directive 85/337/EEC. Only models can give detailed information on the distribution of pollutants with high spatial and temporal resolution, while they allow the decision-maker to devise a range of scenarios, in which the various processes determining the environmental impact can be easily simulated and changed. In June 1991, the Joint Research Centre of the European Commission started an initiative on the sharing of information and possible harmonisation of new approaches to atmospheric dispersion modelling and model evaluation. This initiative has fostered a series of conferences that have been concerned with improvement of ''modelling culture'' in Europe. The 9th International Conference on Harmonisation within atmospheric dispersion modelling for regulatory purposes in Garmisch-Partenkirchen, in Germany/ Bavaria, 1-4 June, 2004, will continue the efforts of the previous conferences. The conference has a role as a forum where users and decision-makers can bring their requirements to the attention of scientists. It is also a natural forum for discussing environmental issues related to the European union enlargement process. The scope of this conference is covered by the following topics: Validation and inter-comparison of models: Model evaluation methodology, experiences with implementation of EU directives; regulatory modelling, short distance dispersion modelling, urban scale and street canyon modelling: Meteorology and air quality, mesoscale meteorology and air quality modelling, environmental impact assessment: Air pollution management and decision support systems. (orig.)

  13. ATMES: An evaluation of long range atmospheric dispersion models using radioactivity data from the Chernobyl accident

    International Nuclear Information System (INIS)

    ATMES was organized in 1989 by CEC, WMO and IAEA with the main purpose of reviewing and calibrating long range atmospheric dispersion models, to identify the more successful approaches. This document provides some findings of the study which employed 21 models from various institutions of 14 countries. They had to produce the model results without knowing in advance the measurements to which their results had to be compared. Many out of the participating models were able to predict the arrival times at the two selected sites using the analysed windfields within a few hours

  14. Numerical modelling of pollution dispersion in 3D atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Benes, L.; Bodnar, T.; Kozel, K. [Czech Technical Univ. of Prague (Czech Republic). Dept. of Technical Mathematics; Fraunie, Ph. [Univ. de Toulon et du Var, La Garde (France). Lab. de Sondages Electromagnetiques et Environnemental Terrestre

    2002-07-01

    The main goal of this work is to present the applicable models and numerical methods for solution of flow and pollution dispersion in 3D atmospheric boundary layer (ABL). Mathematical models are based on the system of Reynolds averaged Navier-Stokes equations and its simplifications. The sets of governing equations are completed by the transport equations for passive impurities and potential temperature. A simple algebraic turbulent closure model is used. The thermal stability phenomenon is taken into account. For each mathematical model a numerical scheme based on finite-difference or finite-volume discretization is proposed and discussed. Some results of numerical tests are presented for pollution dispersion from point sources and flows over simple geometries. (orig.)

  15. The use of atmospheric dispersion models in risk assessment decision support systems for pesticides

    NARCIS (Netherlands)

    Leeuw, de F.A.A.M.; Pul, van W.A.J.; Berg, van den F.; Gilbert, A.J.

    2000-01-01

    In the evaluation of potentially adverse effects of organic chemicals such as pesticides on the environment the atmosphere may play an important role. After its release to the atmosphere the chemical will be transported/dispersed in the atmosphere andfinally it will be removed either by atmospheric-

  16. Impact of atmospheric release in stable night meteorological conditions; can emergency models predict dispersion

    International Nuclear Information System (INIS)

    Atmospheric dispersion of pollutant or radionuclides in stratified meteorological condition, i.e. especially when weather conditions are very stable, mainly at night, is still poorly understood and not well apprehended by the operational atmospheric dispersion models. However, correctly predicting the dispersion of a radioactive plume, and estimating the radiological consequences for the population, following an unplanned atmospheric release of radionuclides are crucial steps in an emergency response. To better understand dispersion in these special weather conditions, IRSN performed a series of 22 air sampling campaigns between 2010 and 2013 in the vicinity of the La Hague nuclear reprocessing plant (AREVA - NC, France), at distances between 200 m and 3000 m from the facility. Krypton-85 (85Kr), a b-and g-emitting radionuclide, released during the reprocessing of spent nuclear fuel was used as a non-reactive tracer of radioactive plumes. Experimental campaigns were realized in stability class stable or very stable (E or F according to Pasquill classification) 18 times, and in neutral conditions (D according to Pasquill classification) 4 times. During each campaign, Krypton-85 real time measurement were made to find the plume around the plant, and then integrated samples (30 min) were collected in bag perpendicularly to the assumed wind direction axis. After measurement by gamma spectrometry, we have, when it was possible, estimate the point of impact and the width of the plume. The objective was to estimate the horizontal dispersion (width) of the plume at ground level in function of the distance and be able to calculate atmospheric transfer coefficients. In a second step, objective was to conclude on the use of common model and on their uncertainties. The results will be presented in terms of impact on the near-field. They will be compared with data obtained in previous years in neutral atmospheric conditions, and finally the results will be confronted with those

  17. Uncertainty modelling of atmospheric dispersion by stochastic response surface method under aleatory and epistemic uncertainties

    Indian Academy of Sciences (India)

    Rituparna Chutia; Supahi Mahanta; D Datta

    2014-04-01

    The parameters associated to a environmental dispersion model may include different kinds of variability, imprecision and uncertainty. More often, it is seen that available information is interpreted in probabilistic sense. Probability theory is a well-established theory to measure such kind of variability. However, not all available information, data or model parameters affected by variability, imprecision and uncertainty, can be handled by traditional probability theory. Uncertainty or imprecision may occur due to incomplete information or data, measurement error or data obtained from expert judgement or subjective interpretation of available data or information. Thus for model parameters, data may be affected by subjective uncertainty. Traditional probability theory is inappropriate to represent subjective uncertainty. Possibility theory is used as a tool to describe parameters with insufficient knowledge. Based on the polynomial chaos expansion, stochastic response surface method has been utilized in this article for the uncertainty propagation of atmospheric dispersion model under consideration of both probabilistic and possibility information. The proposed method has been demonstrated through a hypothetical case study of atmospheric dispersion.

  18. Estimation of tritium dispersion from the spent nuclear fuel reprocessing plant in Rokkasho using an atmospheric dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Koichi; Kakiuchi, Hideki; Iyogi, Takashi; Hisamatsu, Shun' ichi [Institute for Environmental Sciences, Rokkasho, Aomori 039-3212 (Japan); Akata, Naofumi [Institute for Environmental Sciences, Rokkasho, Aomori 039-3212 (Japan); National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Chiang, Jing-Hsien; Suwa, Hiroji [Japan NUS Co., Ltd., Tokyo 160-0023 (Japan)

    2014-07-01

    Japan's first large-scale commercial plant for reprocessing spent nuclear fuel was constructed in Rokkasho, Japan, by Japan Nuclear Fuel Limited (JNFL). Final tests of plant operation carried out with spent fuels since 31 March 2006 have indicated that small amounts of radionuclides (mainly {sup 3}H, {sup 14}C, {sup 85}Kr, and {sup 129}I) are discharged into the atmosphere from the main stack of the plant. To estimate the atmospheric dispersion of {sup 3}H discharged from the plant, we used a combination of the Fifth-Generation Penn State/NCAR Mesoscale Model (MM5) and the CG-MATHEW/ADPIC models, Version 5.0 (ARAC-2). Simulation results were validated with atmospheric {sup 3}H concentrations and wet deposition rates measured at the Institute for Environmental Sciences (IES), located 2.6 km east from the stack. Biweekly atmospheric HTO, HT, and CH3T samples and monthly precipitation samples were collected at IES from April 2006 to February 2009 (the test period). Concentrations of {sup 3}H in the samples were measured with a low-background liquid scintillation counter (LSC-LB5, Hitachi Aloka Medical, Ltd., Tokyo, Japan). To simulate the dispersion of {sup 3}H from the stack, a meteorological field was calculated by MM5 and used as input to ARAC-2, which consists of a mass-consistent wind model and a particle-tracing-type dispersion model. The simulation areas were 315 km x 315 km for MM5 and 50 km x 50 km for ARAC-2. The following meteorological data were input to MM5: grid point data derived from the Mesoscale Model of the Japan Meteorological Agency (JMA), data from JMA's Automated Meteorological Data Acquisition System (AMeDAS), and wind speed and direction at IES and JNFL measured every 10 min. The weekly discharge rates of {sup 3}H disclosed by JNFL were used as the source term for ARAC-2. The concentrations of {sup 3}H in atmospheric moisture and precipitation samples increased from their background values during the test period. As an index of

  19. Estimation of tritium dispersion from the spent nuclear fuel reprocessing plant in Rokkasho using an atmospheric dispersion model

    International Nuclear Information System (INIS)

    Japan's first large-scale commercial plant for reprocessing spent nuclear fuel was constructed in Rokkasho, Japan, by Japan Nuclear Fuel Limited (JNFL). Final tests of plant operation carried out with spent fuels since 31 March 2006 have indicated that small amounts of radionuclides (mainly 3H, 14C, 85Kr, and 129I) are discharged into the atmosphere from the main stack of the plant. To estimate the atmospheric dispersion of 3H discharged from the plant, we used a combination of the Fifth-Generation Penn State/NCAR Mesoscale Model (MM5) and the CG-MATHEW/ADPIC models, Version 5.0 (ARAC-2). Simulation results were validated with atmospheric 3H concentrations and wet deposition rates measured at the Institute for Environmental Sciences (IES), located 2.6 km east from the stack. Biweekly atmospheric HTO, HT, and CH3T samples and monthly precipitation samples were collected at IES from April 2006 to February 2009 (the test period). Concentrations of 3H in the samples were measured with a low-background liquid scintillation counter (LSC-LB5, Hitachi Aloka Medical, Ltd., Tokyo, Japan). To simulate the dispersion of 3H from the stack, a meteorological field was calculated by MM5 and used as input to ARAC-2, which consists of a mass-consistent wind model and a particle-tracing-type dispersion model. The simulation areas were 315 km x 315 km for MM5 and 50 km x 50 km for ARAC-2. The following meteorological data were input to MM5: grid point data derived from the Mesoscale Model of the Japan Meteorological Agency (JMA), data from JMA's Automated Meteorological Data Acquisition System (AMeDAS), and wind speed and direction at IES and JNFL measured every 10 min. The weekly discharge rates of 3H disclosed by JNFL were used as the source term for ARAC-2. The concentrations of 3H in atmospheric moisture and precipitation samples increased from their background values during the test period. As an index of agreement, we used the ratio of the number of estimated values that agreed

  20. Radon dispersion modeling and dose assessment for uranium mine ventilation shaft exhausts under neutral atmospheric stability.

    Science.gov (United States)

    Xie, Dong; Wang, Hanqing; Kearfott, Kimberlee J; Liu, Zehua; Mo, Shunquan

    2014-03-01

    In the present study, the roles of atmospheric wind profiles in the neutral atmosphere and surface roughness parameters in a complex terrain were examined to determine their impacts on radon ((222)Rn) dispersion from an actual uranium mine ventilation shaft. Simulations were completed on (222)Rn dispersion extending from the shaft to a vulnerable distance, near the location of an occupied farmhouse. The eight dispersion scenarios for the ventilation shaft source included four downwind velocities (0.5, 1.0, 2.0 and 4.0 m s(-1)) and two underlying surface roughness characteristics (0.1 m and 1.0 m). (222)Rn distributions and elevated pollution regions were identified. Effective dose estimation methods involving a historical weighting of wind speeds in the direction of interest coupled to the complex dispersion model were proposed. Using this approach, the radiation effects on the residents assumed to be outside at the location of the farm house 250 m downwind from the ventilation shaft outlet were computed. The maximum effective dose rate calculated for the residents at the outside of the farm house was 2.2 mSv y(-1), which is less than the low limit action level of 3-10 mSv y(-1) recommended by the International Commission on Radiological Protection (ICRP) occupational exposure action level for radon. PMID:24378730

  1. Atmospheric Transport Modeling with 3D Lagrangian Dispersion Codes Compared with SF6 Tracer Experiments at Regional Scale

    OpenAIRE

    2007-01-01

    The results of four gas tracer experiments of atmospheric dispersion on a regional scale are used for the benchmarking of two atmospheric dispersion modeling codes, MINERVE-SPRAY (CEA), and NOSTRADAMUS (IBRAE). The main topic of this comparison is to estimate the Lagrangian code capability to predict the radionuclide atmospheric transfer on a large field, in the case of risk assessment of nuclear power plant for example. For the four experiments, the results of calculations show a rather...

  2. Harmonisation within atmospheric dispersion modelling for regulatory purposes. Proceedings. Vol. 1

    International Nuclear Information System (INIS)

    Dispersion modelling has proved to be a very effective tool to assess the environmental impact of human activities to be a very effective tool to assess the environmental impact of human activities on air quality already at the early planning stage. Environmental assessments during planning are required by the EU directive 85/337/EEC. Only models can give detailed information on the distribution of pollutants with high spatial and temporal resolution, while they allow the decision-maker to devise a range of scenarios, in which the various processes determining the environmental impact can be easily simulated and changed. In June 1991, the Joint Research Centre of the European Commission started an initiative on the sharing of information and possible harmonisation of new approaches to atmospheric disperion modelling and model evaluation. This initiative has fostered a series of conferences that have be concerned with improvement of ''modelling culture'' in Europe. The 9th International Conference on Harmonisation within Atmospheric dispersion Modelling for Regulatory Purposes in Garmisch-Partenkirchen, in Germany/Bavaria, 1-4 June, 2004, will continue the efforts of the previous conferences. The conference has a role as a forum where users and decision-makers can bring their requirements to the attention of scientists. It is also a natural forum for discussing environmental issues related to the European Union enlargement process. The scope of this conference is covered by the following topics: 1. Validation and inter-comparison of models: Model evaluation methodology - 2. Experiences with implementation of EU directives: regulatory modelling - 3. Short distance dispersion modelling - 4. Urban scale and street canyon modelling: Meteorology and air quality - 5. Mesoscale meteorology and air quality modelling - 6. Environmental impact assessment: Air pollution management and decision support systems. (orig.)

  3. Radon dispersion modeling and dose assessment for uranium mine ventilation shaft exhausts under neutral atmospheric stability

    International Nuclear Information System (INIS)

    In the present study, the roles of atmospheric wind profiles in the neutral atmosphere and surface roughness parameters in a complex terrain were examined to determine their impacts on radon (222Rn) dispersion from an actual uranium mine ventilation shaft. Simulations were completed on 222Rn dispersion extending from the shaft to a vulnerable distance, near the location of an occupied farmhouse. The eight dispersion scenarios for the ventilation shaft source included four downwind velocities (0.5, 1.0, 2.0 and 4.0 m s−1) and two underlying surface roughness characteristics (0.1 m and 1.0 m). 222Rn distributions and elevated pollution regions were identified. Effective dose estimation methods involving a historical weighting of wind speeds in the direction of interest coupled to the complex dispersion model were proposed. Using this approach, the radiation effects on the residents assumed to be outside at the location of the farm house 250 m downwind from the ventilation shaft outlet were computed. The maximum effective dose rate calculated for the residents at the outside of the farm house was 2.2 mSv y−1, which is less than the low limit action level of 3–10 mSv y−1 recommended by the International Commission on Radiological Protection (ICRP) occupational exposure action level for radon. - Highlights: • Modeling of radon dispersion from uranium mine shafts. • Rn modeling methods include complex meteorology and geography. • Dose computation methods involving historical wind speeds weighting are proposed. • Rn dose rate for the residents near uranium mine shafts are calculated and assessed

  4. Optimisation of 85Kr environmental monitoring to provide a validation of atmospheric dispersion models

    International Nuclear Information System (INIS)

    Oxide fuel reprocessing commenced in the Thorp plant, at Sellafield, in 1994, with a total throughput to date of more than 2000te. From the initial Planning Inquiry through to final licensing, the potential discharges of 85Kr had been an issue of interest to the regulators and the public. This study was intended to further validate the atmospheric dispersion models used at Sellafield and the original estimates of critical group exposure from 85Kr. An extensive environmental monitoring programme has been carried out from 1996 to 1999. Several sampling sites were established around Sellafield and more than 150 samples obtained. Total krypton (stable and radioactive) in air samples was purified using cryogenic distillation. This enabled the activity concentration of 85Kr in air to be determined from the volume of stable 84Kr and the activity of 85Kr (measured by beta counting) assuming a constant mixing ratio of 1.14 ppm(v) of 84Kr in air. Meteorological and stack emissions data were also used as an input to the atmospheric dispersion models. The comparisons of modelled and measured 85Kr concentrations confirmed that the predicted critical group doses, from 85Kr discharges, were conservative. The atmospheric dispersion models used in the dose predictions (NRPB-R91 and UK-ADMS 3.0) were found to over-predict the air concentrations for the Sellafield site situation. The new generation model (UK-ADMS 3.0) provided slightly more conservative air concentration estimates than the NRPB-R91 model, though performance in non-neutral conditions was hard to assess because of the smaller number of data points. (author)

  5. Estimation of 85Kr dispersion from the spent nuclear fuel reprocessing plant in Rokkasho, Japan, using an atmospheric dispersion model

    International Nuclear Information System (INIS)

    The spent nuclear fuel reprocessing plant of Japan Nuclear Fuel Limited (JNFL) located in Rokkasho, Japan, discharged small amounts of 85Kr into the atmosphere during final tests of the plant with actual spent fuel from 31 March 2006 to October 2008. During this period, the gamma-ray dose rates due to discharged 85Kr were higher than the background rates measured at the Institute for Environmental Sciences and at seven monitoring stations of the Aomori prefectural government and JNFL. The dispersion of 85Kr was simulated by means of the fifth-generation Penn State/NCAR Mesoscale Model and the CG-MATHEW/ADPIC models (ver. 5.0) with a vertical terrain-following height coordinate. Although the simulated gamma-ray dose rates due to discharged 85Kr agreed fairly well with measured rates, the agreement between the estimated monthly mean 85Kr concentrations and the observed concentrations was poor. Improvement of the vertical flow of air may lead to better estimation of 85Kr dispersion. (authors)

  6. Modeling of High-altitude Atmospheric Dispersion Using Climate and Meteorological Forecast Data

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, L G; Chin, H S

    2005-03-30

    The overall objective of this study is to provide a demonstration of capability for importing both high altitude meteorological forecast and climatological datasets from NRL into the NARAC modeling system to simulate high altitude atmospheric droplet release and dispersion. The altitude of release for the proposed study is between 60 and 100km altitude. As either standard climatological data (over a period of 40 years) or daily meteorological forecasts can drive the particle dispersion model, we did a limited comparison of simulations with meteorological data and simulations with climatological data. The modeling tools used to address this problem are the National Atmospheric Release Advisory Center (NARAC) modeling system at LLNL which are operationally employed to assist DOE/DHS/DOD emergency response to an atmospheric release of chemical, biological, and radiological contaminants. The interrelation of the various data feeds and codes at NARAC are illustrated in Figure 1. The NARAC scientific models are all verified to both analytic solutions and other codes; the models are validated to field data such as the Prairie Grass study (Barad, 1958). NARAC has multiple real-time meteorological data feeds from the National Weather Service, from the European Center for Medium range Weather Forecasting, from the US Navy, and from the US Air Force. NARAC also keeps a historical archive of meteorological data partially for research purposes. The codes used in this effort were the Atmospheric Data Assimilation and Parameterization Techniques (ADAPT) model (Sugiyama and Chan, 1998) and a development version of the Langrangian Operational Dispersion Integrator (LODI) model (Nasstrom et al., 2000). The use of the NASA GEOS-4 dataset required the use of a development version of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) model (Hodur, 1997; Chin and Glascoe, 2004). The specific goals of this study are the following: (1) Confirm data compatibility of NRL

  7. Modeling the fallout from stabilized nuclear clouds using the HYSPLIT atmospheric dispersion model

    International Nuclear Information System (INIS)

    The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, developed by the National Oceanic and Atmospheric Administration's Air Resources Laboratory, has been configured to simulate the dispersion and deposition of nuclear materials from a surface-based nuclear detonation using publicly available information on nuclear explosions. Much of the information was obtained from “The Effects of Nuclear Weapons” by Glasstone and Dolan (1977). The model was evaluated against the measurements of nuclear fallout from six nuclear tests conducted between 1951 and 1957 at the Nevada Test Site using the global NCEP/NCAR Reanalysis Project (NNRP) and the Weather Research and Forecasting (WRF) meteorological data as input. The model was able to reproduce the general direction and deposition patterns using the coarse NNRP data with Figure of Merit in Space (FMS – the percent overlap between predicted and measured deposition patterns) scores in excess of 50% for four of six simulations for the smallest dose rate contour, with FMS scores declining for higher dose rate contours. When WRF meteorological data were used the FMS scores were 5–20% higher in five of the six simulations, especially at the higher dose rate contours. The one WRF simulation where the scores declined slightly (10–30%) was also the best scoring simulation when using the NNRP data. When compared with measurements of dose rate and time of arrival from the Town Data Base (Thompson et al., 1994), similar results were found with the WRF simulations providing better results for four of six simulations. The overall result was that the different plume simulations using WRF data had more consistent performance than the plume simulations using NNRP data fields. - Highlights: • Modeled the fallout from six Nevada nuclear tests between 1951 and 1957 using HYSPLIT. • Modeled dose rate patterns compared favorably to measurements. • Plume overlap was best for the smallest dose rate

  8. Implicit coupling of turbulent diffusion with chemical reaction mechanisms for prognostic atmospheric dispersion models

    Energy Technology Data Exchange (ETDEWEB)

    Berlowitz, D.R.

    1996-11-01

    In the last few decades the negative impact by humans on the thin atmospheric layer enveloping the earth, the basis for life on this planet, has increased steadily. In order to halt, or at least slow down this development, the knowledge and study of these anthropogenic influence has to be increased and possible remedies have to be suggested. An important tool for these studies are computer models. With their help the atmospheric system can be approximated and the various processes, which have led to the current situation can be quantified. They also serve as an instrument to assess short or medium term strategies to reduce this human impact. However, to assure efficiency as well as accuracy, a careful analysis of the numerous processes involved in the dispersion of pollutants in the atmosphere is called for. This should help to concentrate on the essentials and also prevent excessive usage of sometimes scarce computing resources. The basis of the presented work is the EUMAC Zooming Model (ETM), and particularly the component calculating the dispersion of pollutants in the atmosphere, the model MARS. The model has two main parts: an explicit solver, where the advection and the horizontal diffusion of pollutants are calculated, and an implicit solution mechanism, allowing the joint computation of the change of concentration due to chemical reactions, coupled with the respective influence of the vertical diffusion of the species. The aim of this thesis is to determine particularly the influence of the horizontal components of the turbulent diffusion on the existing implicit solver of the model. Suggestions for a more comprehensive inclusion of the full three dimensional diffusion operator in the implicit solver are made. This is achieved by an appropriate operator splitting. A selection of numerical approaches to tighten the coupling of the diffusion processes with the calculation of the applied chemical reaction mechanisms are examined. (author) figs., tabs., refs.

  9. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

    OpenAIRE

    G. Katata; Chino, M; T. Kobayashi; Terada, H.; Ota, M; Nagai, H.; M. Kajino; Draxler, R; M. C. Hort; Malo, A.; Torii, T.; Y. Sanada

    2014-01-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSP...

  10. Sensitivity analysis of a short distance atmospheric dispersion model applied to the Fukushima disaster

    Science.gov (United States)

    Périllat, Raphaël; Girard, Sylvain; Korsakissok, Irène; Mallet, Vinien

    2015-04-01

    In a previous study, the sensitivity of a long distance model was analyzed on the Fukushima Daiichi disaster case with the Morris screening method. It showed that a few variables, such as horizontal diffusion coefficient or clouds thickness, have a weak influence on most of the chosen outputs. The purpose of the present study is to apply a similar methodology on the IRSN's operational short distance atmospheric dispersion model, called pX. Atmospheric dispersion models are very useful in case of accidental releases of pollutant to minimize the population exposure during the accident and to obtain an accurate assessment of short and long term environmental and sanitary impact. Long range models are mostly used for consequences assessment while short range models are more adapted to the early phases of the crisis and are used to make prognosis. The Morris screening method was used to estimate the sensitivity of a set of outputs and to rank the inputs by their influences. The input ranking is highly dependent on the considered output, but a few variables seem to have a weak influence on most of them. This first step revealed that interactions and non-linearity are much more pronounced with the short range model than with the long range one. Afterward, the Sobol screening method was used to obtain more quantitative results on the same set of outputs. Using this method was possible for the short range model because it is far less computationally demanding than the long range model. The study also confronts two parameterizations, Doury's and Pasquill's models, to contrast their behavior. The Doury's model seems to excessively inflate the influence of some inputs compared to the Pasquill's model, such as the altitude of emission and the air stability which do not have the same role in the two models. The outputs of the long range model were dominated by only a few inputs. On the contrary, in this study the influence is shared more evenly between the inputs.

  11. Atmospheric dispersion modeling at the Rocky Flats Plant. Progress report, December 1981-December 1985

    International Nuclear Information System (INIS)

    The Rocky Flats Plant applies atmospheric dispersion modeling as a tool for Emergency Response, Risk Assessment, and Regulatory Compliance. Extreme variations in terrain around the facility have necessitated the development of an advanced modeling approach. The Terrain-Responsive Atmospheric Code (TRAC) was developed to treat realistically the changing wind, stability, dispersion, and deposition patterns that are experienced in mountainous areas. The result is a detailed picture of dose and deposition patterns associated with postulated or actual releases. A unified approach was taken to modeling needs at Rocky Flats. This produces consistent dose projections for all applications. A Risk Assessment version of TRAC is now operational. A high-speed version of the code is being implemented for Emergency Response, and development of a regulatory version is under way. Public, scientific, and governmental acceptance of TRAC is critical to successful applications at the Rocky Flats Plant. A program of peer review and regulatory approval was initiated to provide a full outside evaluation of our techniques. Full field validation (tracer testing) is key to demonstrating reliability of the TRAC model. A validation study was planned for implementation beginning in early CY-1986. The necessary funding ($500,000) is being sought. Although the TRAC model development and approval program was developed for site-specific needs at the Rocky Flats Plant, potential exists for wider application within the Department of Energy (DOE). The TRAC model can be easily applied at other sites in complex terrain. A coordinated approach to model validation throughout the Albquerque Operations Office (AL) or DOE complexes could prove more cost effective than site-by-site evaluations. Finally, the model approval procedure developed jointly by Rocky Flats and the Environmental Protection Agency (EPA) is general and could be applied to other models or as the basis for a DOE-wide program

  12. IPSN model for the simplified calculation of atmospheric dispersion of accidental releases

    International Nuclear Information System (INIS)

    To assess the atmospheric dispersion of accidental releases, the Institut de Protection et de Surete Nucleaire (IPSN) has developed a so called gaussian plume model. It derives from tri-gaussian puffs, characterized by standard deviations parametrized with respect to the transfer time (for only two classes of vertical atmospheric stability). The analytic form of this model makes it possible to take into account the most important phenomena which change the content of the plume during transfer: reflections, radioactive decay, daughter products, dry and wet deposition. Limitations to the use of this plume model are examined. Its field of application is reduced in the case of weak winds, the more so when the release height is great. A limited number of reference meteorological conditions and standard values for dry deposition velocity (iodine and particles) and the washing rate by rain are proposed, and examples of results are given. This model predicts the order of magnitude of the consequences of accidental atmospheric releases over distances from several hundred meters up to several tens of kilometers

  13. Atmospheric Dispersion Models for the Calculation of Environmental Impact: A Comparative Study

    International Nuclear Information System (INIS)

    In this paper some new comparisons are presented between the codes AERMOD, HPDM and HYSPLIT.The first two are Gaussian stationary plume codes and they were developed to calculate environmental impact produced by chemical contaminants.HYSPLIT is a hybrid code because it uses a Lagrangian reference system to describe the transport of a puff center of mass and uses an Eulerian system to describe the dispersion within the puff.The meteorological and topographic data used in the present work were obtained from runs of the prognostic code RAMS, provided by NOAA. The emission was fixed in 0.3 g/s , 284 K and 0 m/s .The surface rough was fixed in 0.1m and flat terrain was considered.In order to analyze separate effects and to go deeper in the comparison, the meteorological data was split into two, depending on the atmospheric stability class (F to B), and the wind direction was fixed to neglect its contribution to the contaminant dispersion.The main contribution of this work is to provide recommendations about the validity range of each code depending on the model used.In the case of Gaussian models the validity range is fixed by the distance in which the atmospheric condition can be consider homogeneous.In the other hand the validity range of HYSPLIT's model is determined by the spatial extension of the meteorological data.The results obtained with the three codes are comparable if the emission is in equilibrium with the environment.This means that the gases were emitted at the same temperature of the medium with zero velocity.There was an important difference between the dispersion parameters used by the Gaussian codes

  14. Development of NEXRAD Wind Retrievals as Input to Atmospheric Dispersion Models

    Energy Technology Data Exchange (ETDEWEB)

    Fast, Jerome D.; Newsom, Rob K.; Allwine, K Jerry; Xu, Qin; Zhang, Pengfei; Copeland, Jeffrey H.; Sun, Jenny

    2007-03-06

    The objective of this study is to determine the feasibility that routinely collected data from the Doppler radars can appropriately be used in Atmospheric Dispersion Models (ADMs) for emergency response. We have evaluated the computational efficiency and accuracy of two variational mathematical techniques that derive the u- and v-components of the wind from radial velocities obtained from Doppler radars. A review of the scientific literature indicated that the techniques employ significantly different approaches in applying the variational techniques: 2-D Variational (2DVar), developed by NOAA¹s (National Oceanic and Atmospheric Administration's) National Severe Storms Laboratory (NSSL) and Variational Doppler Radar Analysis System (VDRAS), developed by the National Center for Atmospheric Research (NCAR). We designed a series of numerical experiments in which both models employed the same horizontal domain and resolution encompassing Oklahoma City for a two-week period during the summer of 2003 so that the computed wind retrievals could be fairly compared. Both models ran faster than real-time on a typical single dual-processor computer, indicating that they could be used to generate wind retrievals in near real-time. 2DVar executed ~2.5 times faster than VDRAS because of its simpler approach.

  15. A source term estimation method for a nuclear accident using atmospheric dispersion models

    DEFF Research Database (Denmark)

    Kim, Minsik; Ohba, Ryohji; Oura, Masamichi;

    2015-01-01

    The objective of this study is to develop an operational source term estimation (STE) method applicable for a nuclear accident like the incident that occurred at the Fukushima Dai-ichi nuclear power station in 2011. The new STE method presented here is based on data from atmospheric dispersion...... models and short-range observational data around the nuclear power plants.The accuracy of this method is validated with data from a wind tunnel study that involved a tracer gas release from a scaled model experiment at Tokai Daini nuclear power station in Japan. We then use the methodology developed...... and validated through the effort described in this manuscript to estimate the release rate of radioactive material from the Fukushima Dai-ichi nuclear power station....

  16. Screening sensitivity analysis of a radionuclides atmospheric dispersion model applied to the Fukushima disaster

    Science.gov (United States)

    Girard, Sylvain; Korsakissok, Irène; Mallet, Vivien

    2014-10-01

    Numerical models used to forecast the atmospheric dispersion of radionuclides following nuclear accidents are subject to substantial uncertainties. Input data, such as meteorological forecasts or source term estimations, as well as poorly known model parameters contribute for a large part to this uncertainty. A sensitivity analysis with the method of Morris was carried out in the case of the Fukushima disaster as a first step towards the uncertainty analysis of the Polyphemus/Polair3D model. The main difficulties stemmed from the high dimension of the model's input and output. Simple perturbations whose magnitudes were devised from a thorough literature review were applied to 19 uncertain inputs. Several outputs related to atmospheric activity and ground deposition were aggregated, revealing different inputs rankings. Other inputs based on gamma dose rates measurements were used to question the possibility of calibrating the inputs uncertainties. Some inputs, such as the cloud layer thickness, were found to have little influence on most considered outputs and could therefore be safely discarded from further studies. On the contrary, wind perturbations and emission factors for iodine and caesium are predominant. The performance indicators derived from dose rates observations displayed strong sensitivities. This emphasises the share of the overall uncertainty due to input uncertainties and asserts the relevance of the simple perturbation scheme that was employed in this work.

  17. Atmospheric Dispersion Modeling of the February 2014 Waste Isolation Pilot Plant Release

    Energy Technology Data Exchange (ETDEWEB)

    Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Piggott, Tom [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lobaugh, Megan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tai, Lydia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pobanz, Brenda [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Yu, Kristen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-22

    This report presents the results of a simulation of the atmospheric dispersion and deposition of radioactivity released from the Waste Isolation Pilot Plant (WIPP) site in New Mexico in February 2014. These simulations were made by the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory (LLNL), and supersede NARAC simulation results published in a previous WIPP report (WIPP, 2014). The results presented in this report use additional, more detailed data from WIPP on the specific radionuclides released, radioactivity release amounts and release times. Compared to the previous NARAC simulations, the new simulation results in this report are based on more detailed modeling of the winds, turbulence, and particle dry deposition. In addition, the initial plume rise from the exhaust vent was considered in the new simulations, but not in the previous NARAC simulations. The new model results show some small differences compared to previous results, but do not change the conclusions in the WIPP (2014) report. Presented are the data and assumptions used in these model simulations, as well as the model-predicted dose and deposition on and near the WIPP site. A comparison of predicted and measured radionuclide-specific air concentrations is also presented.

  18. Atmospheric dispersion modeling for an accidental release from the Pakistan Research Reactor-1 (PARR-1)

    International Nuclear Information System (INIS)

    Atmospheric dispersion modeling and radiation dose calculations have been performed for a postulated accidental airborne radionuclide release from the Pakistan Research Reactor-1 (PARR-1) appropriate to a power upgrade to 10 MW. Estimates of releases for various radionuclide groups are based upon US-NRC regulatory guide 1.183. Committed Effective Doses (CEDs) to the public at various downwind distances were calculated using a health physics computer code 'HotSpot' developed at the Lawrence Livermore National Laboratory, University of California, USA. The doses were calculated for various atmospheric stability classes, viz., Pasquill categories A-F with site-specific averaged meteorological conditions. The meteorological data on atmospheric stability conditions, mean wind speed and the frequency distribution of wind direction based on data collected near the reactor site have also been analyzed and are presented here. The results indicate that a person located within a downwind distance of about 500 m from the reactor would receive more than the permissible CED under the analyzed severe accident scenario. Analysis of one typical year of wind data indicates that the predominant wind direction is East-North East (ENE), which occurs at the site for more than 15% of the time

  19. Atmospheric dispersion modeling for an accidental release from the Pakistan Research Reactor-1 (PARR-1)

    Energy Technology Data Exchange (ETDEWEB)

    Raza, S. Shoaib [Nuclear Engineering Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan)]. E-mail: ssraza@msn.com; Iqbal, M. [Nuclear Engineering Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan)

    2005-07-15

    Atmospheric dispersion modeling and radiation dose calculations have been performed for a postulated accidental airborne radionuclide release from the Pakistan Research Reactor-1 (PARR-1) appropriate to a power upgrade to 10 MW. Estimates of releases for various radionuclide groups are based upon US-NRC regulatory guide 1.183. Committed Effective Doses (CEDs) to the public at various downwind distances were calculated using a health physics computer code 'HotSpot' developed at the Lawrence Livermore National Laboratory, University of California, USA. The doses were calculated for various atmospheric stability classes, viz., Pasquill categories A-F with site-specific averaged meteorological conditions. The meteorological data on atmospheric stability conditions, mean wind speed and the frequency distribution of wind direction based on data collected near the reactor site have also been analyzed and are presented here. The results indicate that a person located within a downwind distance of about 500 m from the reactor would receive more than the permissible CED under the analyzed severe accident scenario. Analysis of one typical year of wind data indicates that the predominant wind direction is East-North East (ENE), which occurs at the site for more than 15% of the time.

  20. Testing the atmospheric dispersion model of CSA N288.1 with site-specific data

    Energy Technology Data Exchange (ETDEWEB)

    Chouhan, S.L.; Davis, P.A

    2001-01-01

    The atmospheric dispersion component of CSA Standard N288. 1, which provides guidelines for calculating derived release limits, has been tested. Long-term average concentrations of tritium in air were predicted using site-specific release rates and meteorological data and compared with measured concentrations at 43 monitoring sites at all CANDU stations in Canada. The predictions correlate well with the observations but were found to be conservative, overestimating by about 50% on average. The model overpredicted 84% of the time, with the highest prediction lying a factor of 5.5 above the corresponding observation. The model underpredicted the remaining 16% of the time, with the lowest prediction about one-half of the corresponding measurement. Possible explanations for this bias are discussed but no single reason appears capable of accounting for the discrepancy. Rather, the tendency to overprediction seems to result from the cumulative effects of a number of small conservatisms in the model. The model predictions were slightly better when site-specific meteorological data were used in the calculations in place of the default data of N288.1. Some large discrepancies between predictions and observations at specific monitoring sites suggest that it is the measurements rather than the model that are at fault. The testing has therefore provided a check on the observations as well as on the model. Recommendations on model use and data collection are made to improve the level of agreement between predictions and observations in the future. (author)

  1. Testing the atmospheric dispersion model of CSA N288.1 with site-specific data

    International Nuclear Information System (INIS)

    The atmospheric dispersion component of CSA Standard N288. 1, which provides guidelines for calculating derived release limits, has been tested. Long-term average concentrations of tritium in air were predicted using site-specific release rates and meteorological data and compared with measured concentrations at 43 monitoring sites at all CANDU stations in Canada. The predictions correlate well with the observations but were found to be conservative, overestimating by about 50% on average. The model overpredicted 84% of the time, with the highest prediction lying a factor of 5.5 above the corresponding observation. The model underpredicted the remaining 16% of the time, with the lowest prediction about one-half of the corresponding measurement. Possible explanations for this bias are discussed but no single reason appears capable of accounting for the discrepancy. Rather, the tendency to overprediction seems to result from the cumulative effects of a number of small conservatisms in the model. The model predictions were slightly better when site-specific meteorological data were used in the calculations in place of the default data of N288.1. Some large discrepancies between predictions and observations at specific monitoring sites suggest that it is the measurements rather than the model that are at fault. The testing has therefore provided a check on the observations as well as on the model. Recommendations on model use and data collection are made to improve the level of agreement between predictions and observations in the future. (author)

  2. Emulation and Sobol' sensitivity analysis of an atmospheric dispersion model applied to the Fukushima nuclear accident

    Science.gov (United States)

    Girard, Sylvain; Mallet, Vivien; Korsakissok, Irène; Mathieu, Anne

    2016-04-01

    Simulations of the atmospheric dispersion of radionuclides involve large uncertainties originating from the limited knowledge of meteorological input data, composition, amount and timing of emissions, and some model parameters. The estimation of these uncertainties is an essential complement to modeling for decision making in case of an accidental release. We have studied the relative influence of a set of uncertain inputs on several outputs from the Eulerian model Polyphemus/Polair3D on the Fukushima case. We chose to use the variance-based sensitivity analysis method of Sobol'. This method requires a large number of model evaluations which was not achievable directly due to the high computational cost of Polyphemus/Polair3D. To circumvent this issue, we built a mathematical approximation of the model using Gaussian process emulation. We observed that aggregated outputs are mainly driven by the amount of emitted radionuclides, while local outputs are mostly sensitive to wind perturbations. The release height is notably influential, but only in the vicinity of the source. Finally, averaging either spatially or temporally tends to cancel out interactions between uncertain inputs.

  3. Analysis of uncertainties caused by the atmospheric dispersion model in accident consequence assessments with UFOMOD

    International Nuclear Information System (INIS)

    Various techniques available for uncertainty analysis of large computer models are applied, described and selected as most appropriate for analyzing the uncertainty in the predictions of accident consequence assessments. The investigation refers to the atmospheric dispersion and deposition submodel (straight-line Gaussian plume model) of UFOMOD, whose most important input variables and parameters are linked with probability distributions derived from expert judgement. Uncertainty bands show how much variability exists, sensitivity measures determine what causes this variability in consequences. Results are presented as confidence bounds of complementary cumulative frequency distributions (CCFDs) of activity concentrations, organ doses and health effects, partially as a function of distance from the site. In addition the ranked influence of the uncertain parameters on the different consequence types is shown. For the estimation of confidence bounds it was sufficient to choose a model parameter sample size of n (n=59) equal to 1.5 times the number of uncertain model parameters. Different samples or an increase of sample size did not change the 5%-95% - confidence bands. To get statistically stable results of the sensitivity analysis, larger sample sizes are needed (n=100, 200). Random or Latin-hypercube sampling schemes as tools for uncertainty and sensitivity analyses led to comparable results. (orig.)

  4. Estimation Of 137Cs Using Atmospheric Dispersion Models After A Nuclear Reactor Accident

    Science.gov (United States)

    Simsek, V.; Kindap, T.; Unal, A.; Pozzoli, L.; Karaca, M.

    2012-04-01

    Nuclear energy will continue to have an important role in the production of electricity in the world as the need of energy grows up. But the safety of power plants will always be a question mark for people because of the accidents happened in the past. Chernobyl nuclear reactor accident which happened in 26 April 1986 was the biggest nuclear accident ever. Because of explosion and fire large quantities of radioactive material was released to the atmosphere. The release of the radioactive particles because of accident affected not only its region but the entire Northern hemisphere. But much of the radioactive material was spread over west USSR and Europe. There are many studies about distribution of radioactive particles and the deposition of radionuclides all over Europe. But this was not true for Turkey especially for the deposition of radionuclides released after Chernobyl nuclear reactor accident and the radiation doses received by people. The aim of this study is to determine the radiation doses received by people living in Turkish territory after Chernobyl nuclear reactor accident and use this method in case of an emergency. For this purpose The Weather Research and Forecasting (WRF) Model was used to simulate meteorological conditions after the accident. The results of WRF which were for the 12 days after accident were used as input data for the HYSPLIT model. NOAA-ARL's (National Oceanic and Atmospheric Administration Air Resources Laboratory) dispersion model HYSPLIT was used to simulate the 137Cs distrubition. The deposition values of 137Cs in our domain after Chernobyl Nuclear Reactor Accident were between 1.2E-37 Bq/m2 and 3.5E+08 Bq/m2. The results showed that Turkey was affected because of the accident especially the Black Sea Region. And the doses were calculated by using GENII-LIN which is multipurpose health physics code.

  5. Atmospheric modeling of radioactive material dispersion and health risk in Fukushima Daiichi nuclear power plants accident

    International Nuclear Information System (INIS)

    Highlights: ► The radioactive concentrations are treated as dynamical values. ► A possible nuclear accident is simulated for the prediction of atmospheric contaminations. ► The dangerous situations caused by radioisotope release could be announced to the public. ► In the future studies, some other variables are can be considered. - Abstract: The radioactive material dispersion is investigated in terms of the radioactive concentrations. The risk of the radioactive hazard material is important with respect to the public health. The prevailing westerlies region is modeled for the dynamical consequences, whereby the Fukushima nuclear disaster in Japan is modeled. The multiplications effects of the wind values and plume concentrations are obtained. Monte Carlo calculations are performed for wind speed and direction. In Seoul and Pusan, Korea, the Cs-137 has the highest value among the chemical radioactive materials Cs-137, I-131, and Sr-90. The time for highest concentration is shown to be around 48th hour in Seoul and 12th hour in Pusan. Cesium has the highest value in both cities, and iodine has the lowest value in both cities. The wind is assumed to determine the direction of movement. Therefore, the real values are believed to be lower than the calculated results. This modeling could be used for other industrial accident cases in chemical plants

  6. Tracer experiment data sets for the verification of local and meso-scale atmospheric dispersion models including topographic effects

    International Nuclear Information System (INIS)

    Software and data for nuclear energy applications are acquired, tested and distributed by several information centres; in particular, relevant computer codes are distributed internationally by the OECD/NEA Data Bank (France) and by ESTSC and EPIC/RSIC (United States). This activity is coordinated among the centres and is extended outside the OECD area through an arrangement with the IAEA. This article proposes more specifically a scheme for acquiring, storing and distributing atmospheric tracer experiment data (ATE) required for verification of atmospheric dispersion models especially the most advanced ones including topographic effects and specific to the local and meso-scale. These well documented data sets will form a valuable complement to the set of atmospheric dispersion computer codes distributed internationally. Modellers will be able to gain confidence in the predictive power of their models or to verify their modelling skills. (au)

  7. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

    Science.gov (United States)

    Katata, G.; Chino, M.; Kobayashi, T.; Terada, H.; Ota, M.; Nagai, H.; Kajino, M.; Draxler, R.; Hort, M. C.; Malo, A.; Torii, T.; Sanada, Y.

    2015-01-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric and oceanic transport, dispersion and deposition models. The atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition scheme, which deals with dry and fog-water depositions, cloud condensation nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The results revealed that the major releases of radionuclides due to the FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, midnight of 14 March when the SRV (safety relief valve) was opened three times at Unit 2, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of release rates. The simulation by WSPEEDI-II using the new source term reproduced the local and regional patterns of cumulative

  8. Comparison Wind-Tunnel Experiment with Les Modelling of Atmospheric Dispersion over Complex Terrain

    Czech Academy of Sciences Publication Activity Database

    Nosek, Štěpán; Jaňour, Zbyněk; Fuka, V.; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Gulíková, E.

    Hatfield: University of Hertfordshire, 2014 - (Mitto, T.; Fallmann, J.; Mikolajczyk, U.; Suppan, P.; Singh, V.; Sokhi, R.). s. 255-255 ISBN 978-1-909291-20-1. [International Conference on Air Quality - Science and Application /9./. 24.03.2014-28.03.2014, Garmisch-Partenkirchen] R&D Projects: GA TA ČR TA01020428 Institutional support: RVO:61388998 Keywords : wind-tunnel * atmospheric dispersion * LES * coal dust * air pollution * complex terrain Subject RIV: DG - Athmosphere Sciences, Meteorology

  9. Development of local-scale high-resolution atmospheric dispersion model using large-eddy simulation. Part 4. Turbulent flows and plume dispersion in an actual urban area

    International Nuclear Information System (INIS)

    We have developed a local-scale high-resolution atmospheric dispersion model using large-eddy simulation (LOHDIM-LES) to assess the safety at nuclear facilities and to respond to emergency situations resulting from accidental or deliberate releases of radioactive materials (e.g., a terrorist attack in an urban area). In Part 1, the unsteady behavior of a plume dispersing over a flat terrain was successfully simulated. In Parts 2 and 3, LESs of turbulent flows and plume dispersion around an isolated building and in building arrays with different obstacle densities were performed, which showed the basic performance comparable to wind tunnel experimental technique. In this study, we apply the LES model to turbulent flows and plume dispersion in an actual urban area. Although some of the turbulence and dispersion characteristics are quantitatively different from the wind tunnel experimental data, the distribution patterns are generally similar to those of the experiments. It is concluded that our LES model simulates reasonably the unsteady behavior of turbulent flows and plume dispersion even for complex heterogeneous urban areas. (author)

  10. krX system: multi-scale modelling of atmospheric dispersion and consequences assessments for radiological emergencies

    International Nuclear Information System (INIS)

    Full text: In case of a nuclear emergency, the krX system simulates the plume behaviour and assesses consequences of these releases. The krX system consists of a suite of meteorological and atmospheric dispersion models coupled with a consequences model. The meteorological module is essentially the atmospheric model, MM5. For the local scale, the atmospheric dispersion modelling is using the multi-module pX model. PX will provide 3 dispersion models: a pure Gaussian Puff, a Lagrangian model and a mixed Eulerian-Lagrangian one. For the regional to continental scale, the krX system uses a special adaptation of the POLAIR3D/POLYPHEMUS model. POLAIR3D is a chemistry-transport model flexible enough to handle a wide range of applications from passive tracers to complex chemical mechanisms. POLYPHEMUS is a full modelling system for air quality. It is designed to yield up-to-date simulations in a reliable framework: aerosols, data assimilation, ensemble forecast and daily forecasts. We will present the krX system and some comparisons with experimental study. Finally, future developments will be discussed. (author)

  11. Modeling the atmospheric dispersion of radioactive effluents in a nuclear accident situation

    International Nuclear Information System (INIS)

    In case of a nuclear accident, which could lead to release of radioactive contaminants, fastest countermeasures are needed related to sheltering, iodine distribution, evacuation and interdiction of food and water consumption. All these decisions should be based either on estimation of inhaled dose and the dose due to external exposure for public, or on the estimation of radioactive concentration in food (which will depend on the radioactive concentration in air and ground deposition). The dispersion model used, was a Gaussian 'puff' model. The vertical dispersion was considered not dependent on the release high. The used meteorological data are specific for the SCN - Pitesti site, collected every hour for one year. The meteorological data file contains: the wind speed (in m/s), wind direction (degrees clockwise from north), atmospheric stability category, precipitation rate (in mm/h) and the high of the mixing layer (in m). A hypothetical major nuclear accident at TRIGA - SSR of INR - Pitesti, due to a serious damage of the reactor core leading, to a large release of radioactive contaminants was examined. The release was considered as a single phase with of one hour duration. The release factors for the considered isotopic mixture are 100% noble gases (of the reactor core inventory), 40% iodine (of the reactor core inventory) and 40% particulate, i.e., 40% of the fission products of core fission products inventory, released as particles. The accuracy of the model could be increased by implementation of the code on a real-time system, where the acquisition of the parameters done is on-line, namely, the data are introduced as soon as the modification of meteorological and dosimetric conditions are produced. In this case, the parameters used in formulas can be adjusted according with the field situation. Unfortunately the real-time systems need more powerful resources: monitoring stations which can measure and send on-line the data and which can cover a large area

  12. Accuracy of Gaussian plume dispersion model predictions as a function of three atmospheric stability classification calculations

    International Nuclear Information System (INIS)

    Air concentration measurements made at Hanford, WA, for short-term surface-level release of flourescein particles are compared with predicted values derived from curves in Turner's Workbook of Atmospheric Dispersion Estimates. Predictions were determined from these curves based on three different sets of criteria to classify atmospheric stability: namely two different sets of vertical temperature gradient measurements, deltaT/deltaZ, and the standard deviation of the wind direction, σsub(theta), at a height of 1.5m. Results indicate that predictions based on the σsub(theta) method of determining atmospheric stability are more accurate than those based on either set of deltaT/deltaZ measurements considered. However, there was a tendency for all three methods to overpredict tracer concentrations in air. These results have direct application to activities concerned with assessing the impact of radionuclides released to the environment. (author)

  13. Development of local-scale high-resolution atmospheric dispersion model using large-eddy simulation. Part 3. Turbulent flow and plume dispersion in building arrays

    International Nuclear Information System (INIS)

    We have developed a LOcal-scale High-resolution atmospheric DIspersion Model using Large-Eddy Simulation (LOHDIM-LES) to assess the safety at nuclear facilities and to respond to emergencies against accidental or intentional release of radioactive materials (e.g., a terrorist attack in an urban area). In Part 1, the unsteady behavior of a plume over a flat terrain was successfully simulated. In Part 2, a new scheme to generate a spatially developing turbulent boundary layer flow was proposed. Then, the large-eddy simulation (LES) model for turbulent flow and plume dispersion around an isolated building was validated. In this study, we extend the LES model to turbulent flows and plume dispersion in various building arrays that represent typical urban surface geometries. Concerning the characteristics of flow and dispersion in building arrays, the flow patterns associated with obstacle densities and the distribution patterns of mean and root-mean-square (r.m.s.) concentrations agree well with those of the wind tunnel experiments. It is shown that the LES model successfully simulates the unsteady behaviors of turbulent flows and plume dispersion in urban-type surface geometries. (author)

  14. Applicability of a high-resolution meso-scale meteorological model to a near-field-scale atmospheric dispersion problem

    International Nuclear Information System (INIS)

    This study examines the feasibility of numerical simulations using a meso-scale meteorological model (NuWFAS: Numerical Weather Forecasting and Analysis System) for a near-field-scale atmospheric dispersion problem. A series of observation data from a field tracer experiment was used for the validation of the model. In the experiments, the tracer was released from a tower at a height of 95 m. The receptors were located on the arc lines with distances from the source of 400, 750, 1500, and 3000 m. The numerical simulations were implemented with two different minimum spatial resolutions of 100 m and 300 m. The meteorological fields were reproduced with a reasonable accuracy, showing the less dependency on the mesh sizes of the simulation. The dispersion fields were also less dependent on the spatial resolutions except for the stable atmospheric conditions. In stable conditions, the smaller spatial resolution leads to the higher surface concentrations due to the larger turbulent diffusions. In most cases, the predicted surface concentrations agreed with the observation within the factor of ten. However, the simulation tends to underestimate the surface concentrations in stable conditions, whereas it overestimates in unstable conditions. Our study revealed that the limitation of the model in estimating the turbulent diffusion coefficients for thermally stratified conditions is the one cause of these trends. The current model underestimates the influences of atmospheric stability, which is one of the most important factors for the near-field-scale atmospheric dispersion. (author)

  15. An analytical model for dispersion of material in the atmospheric planetary boundary layer in presence of precipitation

    International Nuclear Information System (INIS)

    An analytical model for the dispersion of particulates and finely divided material released into the atmosphere near the ground is presented. The possible precipitation when the particles are dense enough and large enough to have deposition velocity, is taken into consideration. The model is derived analytically in the mixing layer or Ekman boundary layer where the mixing process is a direct consequence of turbulent and convective motions generated in the boundary layer. (author)

  16. DUSTRAN 1.0 User’s Guide: A GIS-Based Atmospheric Dust Dispersion Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    Allwine, K Jerry; Rutz, Frederick C.; Shaw, William J.; Rishel, Jeremy P.; Fritz, Brad G.; Chapman, Elaine G.; Hoopes, Bonnie L.; Seiple, Timothy E.

    2006-09-22

    The U.S. Department of Energy’s Pacific Northwest National Laboratory just completed a multi-year project to develop a fully tested and documented atmospheric dispersion modeling system (DUST TRANsport or DUSTRAN) to assist the U.S. Department of Defense in addressing particulate air quality issues at military training and testing ranges. This manual documents the DUSTRAN modeling system and includes installation instructions, a user’s guide, and detailed example tutorials.

  17. UFOMOD - atmospheric dispersion and deposition

    International Nuclear Information System (INIS)

    The report gives an introduction into the modelling of atmospheric dispersion and deposition which has been implemented in the new program system UFOMOD for assessing the consequences after nuclear accidents. According to the new structure of UFOMOD, different trajectory models with ranges of validity near to the site and at far distances are applied. Emphasis is laid on the description of the segmented plume model MUSEMET and its affilated submodels, being the removal of activity from the cloud by dry and wet deposition, and special effects like plume rise and the behaviour of plumes released into building wakes. In addition, the evaluation of γ-dose correction factors to take account of the finite extent of the radioactive plume in the near range (up to about 20 km) are described. Only brief introductions are given into the principles of the other models available: the puff model RIMPUFF, the long-range puff model MESOS, and the special straight-line Gaussian model ISOLA which are used if low-level long-duration releases are considered. To define starting times of weather sequences and the probabilities of occurrence of these sequences, it is convenient to perform stratified sampling. Therefore, the preprocessing program package METSAM has been developed to perform for generic ACAs a random sampling of weather sequences out off a population of classified weather conditions. The sampling procedure and a detailed input/output (I/O) description is presented and an additional appendix, respectively. A general overview on the I/O structure of MUSEMET as well as a brief user guide to run the KfK version of the MESOS code are also given in the appendix. (orig.)

  18. ATMOSPHERIC DISPERSION OF RADIOACTIVE DEBRIS RELEASED IN CASE OF NUCLEAR EXPLOSION USING THE NORWEGIAN SNAP MODEL

    OpenAIRE

    Bartnicki, Jerzy; Saltbones, Jørgen

    2008-01-01

    Abstract: Severe Nuclear Accident Program (SNAP) has been developed at the Norwegian Meteorological Institute (met.no) for modelling dispersion of radioactive debris in case of nuclear accidents. The model has been tested based on the data available from the Chernobyl accident as well as from the ETEX experiments. The main user of model results is the Norwegian Radiation Protection Authority (NRPA) which is responsible for calculating doses in case of a real accident. The model is fu...

  19. Improved Meteorological Input for Atmospheric Release Decision support Systems and an Integrated LES Modeling System for Atmospheric Dispersion of Toxic Agents: Homeland Security Applications

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, E; Simpson, M; Larsen, S; Gash, J; Aluzzi, F; Lundquist, J; Sugiyama, G

    2010-04-26

    When hazardous material is accidently or intentionally released into the atmosphere, emergency response organizations look to decision support systems (DSSs) to translate contaminant information provided by atmospheric models into effective decisions to protect the public and emergency responders and to mitigate subsequent consequences. The Department of Homeland Security (DHS)-led Interagency Modeling and Atmospheric Assessment Center (IMAAC) is one of the primary DSSs utilized by emergency management organizations. IMAAC is responsible for providing 'a single piont for the coordination and dissemination of Federal dispersion modeling and hazard prediction products that represent the Federal position' during actual or potential incidents under the National Response Plan. The Department of Energy's (DOE) National Atmospheric Release Advisory Center (NARAC), locatec at the Lawrence Livermore National Laboratory (LLNL), serves as the primary operations center of the IMAAC. A key component of atmospheric release decision support systems is meteorological information - models and data of winds, turbulence, and other atmospheric boundary-layer parameters. The accuracy of contaminant predictions is strongly dependent on the quality of this information. Therefore, the effectiveness of DSSs can be enhanced by improving the meteorological options available to drive atmospheric transport and fate models. The overall goal of this project was to develop and evaluate new meteorological modeling capabilities for DSSs based on the use of NASA Earth-science data sets in order to enhance the atmospheric-hazard information provided to emergency managers and responders. The final report describes the LLNL contributions to this multi-institutional effort. LLNL developed an approach to utilize NCAR meteorological predictions using NASA MODIS data for the New York City (NYC) region and demonstrated the potential impact of the use of different data sources and data

  20. SPRAYTRAN USER'S GUIDE: A GIS-BASED ATMOSPHERIC SPRAY DROPLET DISPERSION MODELING SYSTEM

    Science.gov (United States)

    The offsite drift of pesticide from spray operations is an ongoing source of concern. The SPRAY TRANsport (SPRAYTRAN) system, documented in this report, incorporates the near-field spray application model, AGDISP, into a meso-scale atmospheric transport model. The AGDISP model ...

  1. Atmospheric Chemistry in Existing Air Atmospheric Dispersion Models and Their Applications: Trends, Advances and Future in Urban Areas in Ontario, Canada and in Other Areas of the World

    Directory of Open Access Journals (Sweden)

    Barbara Laskarzewska

    2009-03-01

    Full Text Available Air quality is a major concern for the public. Therefore, the reliability in modeling and predicting the air quality accurately is of a major interest. This study reviews existing atmospheric dispersion models, specifically, the Gaussian Plume models and their capabilities to handle the atmospheric chemistry of nitrogen oxides (NOx and sulfur dioxides (SO2. It also includes a review of wet deposition in the form of in-cloud, below cloud, and snow scavenging. Existing dispersion models are investigated to assess their capability of handling atmospheric chemistry, specifically in the context of NOx and SO2 substances and their applications to urban areas. A number of previous studies have been conducted where Gaussian dispersion model was applied to major cities around the world such as London, Helsinki, Kanto, and Prague, to predict ground level concentrations of NOx and SO2. These studies demonstrated a good agreement between the modeled and observed ground level concentrations of NOx and SO2. Toronto, Ontario, Canada is also a heavily populated urban area where a dispersion model could be applied to evaluate ground level concentrations of various contaminants to better understand the air quality. This paper also includes a preliminary study of road emissions for a segment of the city of Toronto and its busy streets during morning and afternoon rush hours. The results of the modeling are compared to the observed data. The small scale test of dispersion of NO2 in the city of Toronto was utilized for the local hourly meteorological data and traffic emissions. The predicted ground level concentrations were compared to Air Quality Index (AQI data and showed a good agreement. Another improvement addressed here is a discussion on various wet deposition such as in cloud, below cloud, and snow.

  2. Application of data assimilation to improve the forecasting capability of an atmospheric dispersion model for a radioactive plume

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, H.J. [Nuclear Environment Safety Research Center, Korea Atomic Energy Research Institute, 150, Dukjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)], E-mail: jeong1208@kaeri.re.kr; Han, M.H.; Hwang, W.T.; Kim, E.H. [Nuclear Environment Safety Research Center, Korea Atomic Energy Research Institute, 150, Dukjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2008-05-15

    Modeling an atmospheric dispersion of a radioactive plume plays an influential role in assessing the environmental impacts caused by nuclear accidents. The performance of data assimilation techniques combined with Gaussian model outputs and measurements to improve forecasting abilities are investigated in this study. Tracer dispersion experiments are performed to produce field data by assuming a radiological emergency. Adaptive neuro-fuzzy inference system (ANFIS) and linear regression filter are considered to assimilate the Gaussian model outputs with measurements. ANFIS is trained so that the model outputs are likely to be more accurate for the experimental data. Linear regression filter is designed to assimilate measurements similar to the ANFIS. It is confirmed that ANFIS could be an appropriate method for an improvement of the forecasting capability of an atmospheric dispersion model in the case of a radiological emergency, judging from the higher correlation coefficients between the measured and the assimilated ones rather than a linear regression filter. This kind of data assimilation method could support a decision-making system when deciding on the best available countermeasures for public health from among emergency preparedness alternatives.

  3. Atmospheric and dispersion modeling in areas of highly complex terrain employing a four-dimensional data assimilation technique

    Energy Technology Data Exchange (ETDEWEB)

    Fast, J.D.; O`Steen, B.L.

    1994-12-31

    The results of this study indicate that the current data assimilation technique can have a positive impact on the mesoscale flow fields; however, care must be taken in its application to grids of relatively fine horizontal resolution. Continuous FDDA is a useful tool in producing high-resolution mesoscale analysis fields that can be used to (1) create a better initial conditions for mesoscale atmospheric models and (2) drive transport models for dispersion studies. While RAMS is capable of predicting the qualitative flow during this evening, additional experiments need to be performed to improve the prognostic forecasts made by RAMS and refine the FDDA procedure so that the overall errors are reduced even further. Despite the fact that a great deal of computational time is necessary in executing RAMS and LPDM in the configuration employed in this study, recent advances in workstations is making applications such as this more practical. As the speed of these machines increase in the next few years, it will become feasible to employ prognostic, three-dimensional mesoscale/transport models to routinely predict atmospheric dispersion of pollutants, even to highly complex terrain. For example, the version of RAMS in this study could be run in a ``nowcasting`` model that would continually assimilate local and regional observations as soon as they become available. The atmospheric physics in the model would be used to determine the wind field where no observations are available. The three-dimensional flow fields could be used as dynamic initial conditions for a model forecast. The output from this type of modeling system will have to be compared to existing diagnostic, mass-consistent models to determine whether the wind field and dispersion forecasts are significantly improved.

  4. Atmospheric dispersion modeling and radiological safety analysis for a hypothetical accident of Ghana Research Reactor-1 (GHARR-1)

    International Nuclear Information System (INIS)

    Highlights: • An atmospheric dispersion model for a hypothetical accident of Ghana Research Reactor-1 (GHARR-1) was developed. • Radiological safety analysis after the postulated accident was also carried out. • The MCNPX and HotSpot codes were used to achieve the objectives of our study. • All the values of effective dose obtained following the accident were far below the regulatory limits. - Abstract: Atmospheric dispersion modeling and radiological safety analysis were performed for a postulated accident scenario of the generic Low-Enriched Uranium (LEU) Ghana Research Reactor-1 (GHARR-1) core. The source term was generated from an inventory of peak radioisotope activities released by using the isotope generation code MCNPX. The health physics code, HotSpot, was used to perform the atmospheric transport modeling which was then applied to calculate the total effective dose and how it would be distributed to human organs as a function of distance downwind. All accident scenarios were selected from the GHARR-1 Safety Analysis Report (SAR), assuming that the activities were released to the atmosphere after a design basis accident. The adopted methodology was the use of predominant site-specific meteorological data and dispersion modeling theories to analyze the incident of a hypothetical release to the environment of some selected radionuclides from the site and evaluate to what extent such a release may have radiological effects on the public. The results indicate that all the values of Effective dose obtained, with the maximum of 2.62 × 10−2 mSv at 110 m from the reactor, were far below the regulatory limits, making the use of the reactor safe, even in the event of severe accident scenario

  5. Distributed emergency response system to model dispersion and deposition of atmospheric releases

    International Nuclear Information System (INIS)

    Aging hardware and software and increasing commitments by the Departments of Energy and Defense have led us to develop a new, expanded system to replace the existing Atmospheric Release Advisory Capability (ARAC) system. This distributed, computer-based, emergency response system is used by state and federal agencies to assess the environmental health hazards resulting from an accidental release of radioactive material into the atmosphere. Like its predecessor, the expanded system uses local meteorology (e.g., wind speed and wind direction), as well as terrain information, to simulate the transport and dispersion of the airborne material. The system also calculates deposition and dose and displays them graphically over base maps of the local geography for use by on-site authorities. This paper discusses the limitations of the existing ARAC system. It also discusses the components and functionality of the new system, the technical difficulties encountered and resolved in its design and implementation, and the software methodologies and tools employed in its development

  6. A study on atmospheric dispersion around Kalpakkam coastal site using a non-hydrostatic model and comparison with field data

    International Nuclear Information System (INIS)

    Study of the sea breeze characteristics and Thermal Internal Boundary Layer (TIBL) is very important to understand the dispersion characteristics of air pollutants near coastal area. In the present paper, dispersion characteristics near Kalpakkam coastal area are studied and discussed by simulating sea breeze characteristics and TIBL using a non-hydrostatic mesoscale model in its two dimensional form. The model is run with surface physics, simplified radiation physics and turbulent kinetic energy (TKE) closure scheme for diffusion. A joint meteorological field experiment was carried out by IITM-Pune at Kalpakkam by deploying state of art sensors and tether balloon systems for observing the height profiles of meteorological parameters. The data taken from the field experiment is used here to compare the simulations. Results shows that the onset of sea breeze is one hour before as observed from the field experiment. Slight difference is also seen in wind speed and temperature. Spatial variation of the dispersion pattern could be understood from the simulated TKE profile. From the study, it is shown that the model gives only a over all picture of the real scenario and successful simulations require the inclusion of more atmospheric dynamics such as microphysics, cumulus parameterization and atmospheric radiation. (author)

  7. Radionuclide dispersion in the atmosphere

    International Nuclear Information System (INIS)

    The instantaneous liberation of radionuclides in the atmosphere is studied in three dimensions, according to the formalism of the diffusion theory. The analytical solution, expose to gravitational and an atmospherical effects, is combined with the discretization of space and time in the calculation of levels of exposure. A typical inventory (for a PWR) was considered in the calculation of immersion doses, and the results permitted a comparative analysis among the different existing models. (Author)

  8. Atmospheric dispersion of radionuclides from uranium mill tailings disposal sites

    International Nuclear Information System (INIS)

    This report describes the study of generation and dispersion of airborne radionuclide species from an hypothetical tailings disposal site. The radionuclides are followed along atmospheric dispersion pathways. Estimates of public radiation dose impact were made based on: 1) the behaviour of the hypothetical site and tailings; 2) atmospheric dispersion from such a site located in Northern Ontario. This, the 'Atmospheric Technical Appendix' describes important aspects of the atmospheric modelling process, and findings resulting from that process. It does not attempt to predict real radiation doses, or real atmospheric radionuclide dispersion patterns for any specific site whether existing or projected

  9. A computer programmed model for calculation of fall and dispersion of particles in the atmosphere

    International Nuclear Information System (INIS)

    An atmospheric model has been designed and developed to provide estimates of air concentrations or ground deposit densities of particles released in the atmosphere up to 90-km altitude. Particle density and diameter may range from 1 to 10 g/cm3 and about 3 to 300μ, respectively, for given instantaneous point or line sources. The particle cloud is allowed to move horizontally in accordance with analytically simulated winds and to fall at terminal velocity plus vertical air velocity. Small-scale cloud growth rate is specified empirically at values based on past instantaneous tracer experiments while large-scale growth results from trajectory subdivision and divergence of new particle trajectories. Some specific computer runs at Sandia were done to assess hazards resulting from possible rocket abort situations and atmospheric re-entry from improper orbits of isotopic or reactor power supplies. The results have been compared with other modes of estimation derived from simpler models of world-wide contaminant spread. While existing data are insufficient for full verification, it is felt that the present model is one of the most comprehensive and realistic available. (author)

  10. Some Observational and Modeling Studies of the Atmospheric Boundary Layer at Mississippi Gulf Coast for Air Pollution Dispersion Assessment

    Directory of Open Access Journals (Sweden)

    Anjaneyulu Yerramilli

    2008-12-01

    Full Text Available Coastal atmospheric conditions widely vary from those over inland due to the land-sea interface, temperature contrast and the consequent development of local circulations. In this study a field meteorological experiment was conducted to measure vertical structure of boundary layer during the period 25-29 June, 2007 at three locations Seabee base, Harrison and Wiggins sites in the Mississippi coast. A GPS Sonde along with slow ascent helium balloon and automated weather stations equipped with slow and fast response sensors were used in the experiment. GPS sonde were launched at three specific times (0700 LT, 1300 LT and 1800 LT during the experiment days. The observations indicate shallow boundary layer near the coast which gradually develops inland. The weather research and forecasting (WRF meso-scale atmospheric model and a Lagrangian particle dispersion model (HYSPLIT are used to simulate the lower atmospheric flow and dispersion in a range of 100 km from the coast for 28-30 June, 2007. The simulated meteorological parameters were compared with the experimental observations. The meso-scale model results show significant temporal and spatial variations in the meteorological fields as a result of development of sea breeze flow, its coupling with the large scale flow field and the ensuing alteration in the mixing depth across the coast. Simulated ground-level concentrations of SO2 from four elevated point sources located along the coast indicate diurnal variation and impact of the local sea-land breeze on the direction of the plume. Model concentration levels were highest during the stable morning condition and during the sea-breeze time in the afternoon. The highest concentrations were found up to 40 km inland during sea breeze time. The study illustrates the application of field meteorological observations for the validation of WRF which is coupled to HYSPLIT for dispersion assessment in the coastal region.

  11. Validation of a Lagrangian atmospheric dispersion model against middle-range scale measurements of 85Kr concentration in Japan

    International Nuclear Information System (INIS)

    The Lagrangian atmospheric dispersion model of the computer-based nuclear emergency response system WSPEEDI-II was validated with the measured 85Kr concentrations in tens-of- to hundreds-of-km (middle-range) scale area by conducting dispersion simulations using the release rate from the nuclear fuel reprocessing plant in Rokkasho, Japan. The calculated weekly concentrations of 85Kr in two simulation cases during April and September in 2008 agreed with the measurements within a factor of two at the sampling sites 170 to 2000 km away from the plant. However, the sensitivity analysis of horizontal grid resolution of the meteorological model ranging from 2 to 54 km showed that the calculated results had the dependency on the grid resolution, i.e., the calculated concentrations became low compared with the results with the grid resolution of 54 km as the grid resolution became high. An empirical modification of the horizontal diffusion parameter used for long-range dispersions by WSPEEDI-II was attempted based on the sensitivity analysis to reduce the redundant diffusion effect in dispersion simulations with relatively high grid resolution. The modified horizontal diffusion parameter contributed to reduce the dependency of calculated concentrations on the horizontal grid resolution. (author)

  12. Analysis of the experimental data of air pollution using atmospheric dispersion modeling and rough set

    International Nuclear Information System (INIS)

    This thesis contains four chapters and list of references:In chapter 1, we introduce a brief survey about the atmospheric concepts and the topological methods for data analysis.In section 1.1, we give introduce a general introduction. We recall some of atmospheric fundamentals in Section 1.2. Section 1.3, shows the concepts of modern topological methods for data analysis.In chapter 2, we have studied the properties of atmosphere and focus on concept of Rough set and its properties. This concepts of rough set has been applied to analyze the atmospheric data.In section 2.1, we introduce a general introduction about concept of rough set and properties of atmosphere. Section 2.2 focuses on the concept of rough set and its properties and generalization of approximation of rough set theory by using topological space. In section 2.3 we have studied the stabilities of atmosphere for Inshas location for all seasons using different schemes and compared these schemes using statistical and rough set methods. In section 2.4, we introduce mixing height of plume for all seasons. Section 2.5 introduced seasonal surface layer turbulence processes for Inshas location. Section 2.6 gives a comparison between the seasonal surface layer turbulence processes for Inshas location and for different locations using rough set theory.In chapter 3 we focus on the concept of variable precision rough set (VPRS) and its properties and using it to compare, between the estimated and observed data of the concentration of air pollution for Inshas location. In Section 3.1 we introduce a general introduction about VPRS and air pollution. In Section 3.2 we have focused on the concept and properties of VPRS. In Section 3.3 we have introduced a method to estimate the concentration of air pollution for Inshas location using Gaussian plume model. Section 3.4 has showed the experimental data. The estimated data have been compared with the observed data using statistical methods in Section 3.5. In Section 3

  13. VALDRIFT 1.0: A valley atmospheric dispersion model with deposition

    Energy Technology Data Exchange (ETDEWEB)

    Allwine, K.J.; Bian, X.; Whiteman, C.D.

    1995-05-01

    VALDRIFT version 1.0 is an atmospheric transport and diffusion model for use in well-defined mountain valleys. It is designed to determine the extent of ddft from aedal pesticide spraying activities, but can also be applied to estimate the transport and diffusion of various air pollutants in valleys. The model is phenomenological -- that is, the dominant meteorological processes goveming the behavior of the valley atmosphere are formulated explicitly in the model, albeit in a highly parameterized fashion. The key meteorological processes treated are: (1) nonsteady and nonhomogeneous along-valley winds and turbulent diffusivities, (2) convective boundary layer growth, (3) inversion descent, (4) noctumal temperature inversion breakup, and (5) subsidence. The model is applicable under relatively cloud-free, undisturbed synoptic conditions and is configured to operate through one diumal cycle for a single valley. The inputs required are the valley topographical characteristics, pesticide release rate as a function of time and space, along-valley wind speed as a function of time and space, temperature inversion characteristics at sunrise, and sensible heat flux as a function of time following sunrise. Default values are provided for certain inputs in the absence of detailed observations. The outputs are three-dimensional air concentration and ground-level deposition fields as a function of time.

  14. Final Technical Report: Development of the DUSTRAN GIS-Based Complex Terrain Model for Atmospheric Dust Dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Allwine, K Jerry; Rutz, Frederick C.; Shaw, William J.; Rishel, Jeremy P.; Fritz, Brad G.; Chapman, Elaine G.; Hoopes, Bonnie L.; Seiple, Timothy E.

    2007-05-01

    Activities at U.S. Department of Defense (DoD) training and testing ranges can be sources of dust in local and regional airsheds governed by air-quality regulations. The U.S. Department of Energy’s Pacific Northwest National Laboratory just completed a multi-year project to develop a fully tested and documented atmospheric dispersion modeling system (DUST TRANsport or DUSTRAN) to assist the DoD in addressing particulate air-quality issues at military training and testing ranges.

  15. Atmospheric Transport Modeling with 3D Lagrangian Dispersion Codes Compared with SF6 Tracer Experiments at Regional Scale

    Directory of Open Access Journals (Sweden)

    François Van Dorpe

    2007-01-01

    Full Text Available The results of four gas tracer experiments of atmospheric dispersion on a regional scale are used for the benchmarking of two atmospheric dispersion modeling codes, MINERVE-SPRAY (CEA, and NOSTRADAMUS (IBRAE. The main topic of this comparison is to estimate the Lagrangian code capability to predict the radionuclide atmospheric transfer on a large field, in the case of risk assessment of nuclear power plant for example. For the four experiments, the results of calculations show a rather good agreement between the two codes, and the order of magnitude of the concentrations measured on the soil is predicted. Simulation is best for sampling points located ten kilometers from the source, while we note a divergence for more distant points results (difference in concentrations by a factor 2 to 5. This divergence may be explained by the fact that, for these four experiments, only one weather station (near the point source was used on a field of 10 000 km2, generating the simulation of a uniform wind field throughout the calculation domain.

  16. Atmospheric Transport Modeling with 3D Lagrangian Dispersion Codes Compared with SF6 Tracer Experiments at Regional Scale

    International Nuclear Information System (INIS)

    The results of four gas tracer experiments of atmospheric dispersion on a regional scale are used for the benchmarking of two atmospheric dispersion modeling codes, MINERVE-SPRAY (CEA), and NOSTRADAMUS (IBRAE). The main topic of this comparison is to estimate the Lagrangian code capability to predict the radionuclide atmospheric transfer on a large field, in the case of risk assessment of nuclear power plant for example. For the four experiments, the results of calculations show a rather good agreement between the two codes, and the order of magnitude of the concentrations measured on the soil is predicted. Simulation is best for sampling points located ten kilometers from the source, while we note a divergence for more distant points results (difference in concentrations by a factor 2 to 5). This divergence may be explained by the fact that, for these four experiments, only one weather station (near the point source) was used on a field of 10000 km2, generating the simulation of a uniform wind field throughout the calculation domain.

  17. Atmospheric dispersion modeling and radiological safety analysis for a hypothetical accident of Ghana Research Reactor -1 (GHARR-1)

    International Nuclear Information System (INIS)

    This work presents the environmental impact analysis of some selected radionuclides released from the Ghana Research Reactor- 1 (GHARR-1) after a hypothetical postulated accidents scenario. The source term was identified and generated from an inventory of radioisotopes released during the accident. Atmospheric transport model was then applied to calculate the total effective dose and how it would be distributed to different organs of the human body as a function of distance downwind. All accident scenarios were selected from GHARR-1 Safety Analysis Report. After the source term was identified the MCNPX code was used to perform the core burnup/depletion analysis. The assumption was made that the activities were released to the atmosphere under a horse design basis accident scenario. The gaussian dose calculation method was applied, coded in Hotspot, a Healthy Physics computer code. This served as the computational tool to perform the atmospheric dispersion modeling and was used to calculate radionuclide concentration at downwind location. Based upon predominant meteorological conditions at the site, the adopted strategy was to use site-specific meteorological data and dispersion modeling to analyze the hypothetical release to the environment of radionuclides and evaluate to what extent such a release may have radiological effects on the public. Final data were processed and presented as Total Effective Dose Equivalent as a function of time and distance of deposition. The results indicate that all the values of Effective dose obtained are far below the regulatory limits, making the use of the reactor safe, even in the case of worst accident scenario where all the fission products were released into the atmosphere. (au)

  18. Assessment of wind characteristics and atmospheric dispersion modeling of 137Cs on the Barakah NPP area in the USA

    International Nuclear Information System (INIS)

    This paper presents the results of an analysis of wind characteristics and atmosphere dispersion modeling that are based on computational simulation and part of a preliminary study evaluating environmental radiation monitoring system (ERMS) positions within the Barakah nuclear power plant (BNPP). The return period of extreme wind speed was estimated using the Weibull distribution over the life time of the BNPP. In the annual meteorological modeling, the winds from the north and west accounted for more than 90 % of the wind directions. Seasonal effects were not represented. However, a discrepancy in the tendency between daytime and nighttime was observed. Six variations of cesium-137 (137Cs) dispersion test were simulated under severe accident condition. The 137Cs dispersion was strongly influenced by the direction and speed of the main wind. A virtual receptor was set and calculated for observation of the 137Cs movement and accumulation. The results of the surface roughness effect demonstrated that the deposition of 137Cs was affected by surface condition. The results of these studies offer useful information for developing environmental radiation monitoring systems (ERMSs) for the BNPP and can be used to assess the environmental effects of new nuclear power plant.

  19. Assessment of wind characteristics and atmospheric dispersion modeling of {sup 137}Cs on the Barakah NPP area in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Kuk; Lee, Kun Jai; Yun, Jong IL [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Jae Chul; Belorid, Miloslav [Institute of Environmental Research, Chuncheon (Korea, Republic of); Beeley, Philip A. [Khalifa University of Science, Technology and Research, Dubai (Antigua and Barbuda)

    2014-08-15

    This paper presents the results of an analysis of wind characteristics and atmosphere dispersion modeling that are based on computational simulation and part of a preliminary study evaluating environmental radiation monitoring system (ERMS) positions within the Barakah nuclear power plant (BNPP). The return period of extreme wind speed was estimated using the Weibull distribution over the life time of the BNPP. In the annual meteorological modeling, the winds from the north and west accounted for more than 90 % of the wind directions. Seasonal effects were not represented. However, a discrepancy in the tendency between daytime and nighttime was observed. Six variations of cesium-137 ({sup 137}Cs) dispersion test were simulated under severe accident condition. The {sup 137}Cs dispersion was strongly influenced by the direction and speed of the main wind. A virtual receptor was set and calculated for observation of the {sup 137}Cs movement and accumulation. The results of the surface roughness effect demonstrated that the deposition of {sup 137}Cs was affected by surface condition. The results of these studies offer useful information for developing environmental radiation monitoring systems (ERMSs) for the BNPP and can be used to assess the environmental effects of new nuclear power plant.

  20. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

    OpenAIRE

    G. Katata; Chino, M; T. Kobayashi; Terada, H.; Ota, M; Nagai, H.; M. Kajino; Draxler, R; M. C. Hort; Malo, A.; Torii, T.; Y. Sanada

    2015-01-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measure...

  1. A RECOMMENDED PASQUILL-GIFFORD STABILITY CLASSIFICATION METHOD FOR SAFETY BASIS ATMOSPHERIC DISPERSION MODELING AT SRS

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, C.

    2012-03-28

    Several of the most common methods for estimating Pasquill-Gifford (PG) stability (turbulence) class were evaluated for use in modeling the radiological consequences of SRS accidental releases using the MELCOR Accident Consequence Code System, Ver. 2 (MACCS2). Evaluation criteria included: (1) the ability of the method to represent diffusion characteristics above a predominantly forested landscape at SRS, (2) suitability of the method to provide data consistent with the formulation of the MACCS2 model, and (3) the availability of onsite meteorological data to support implementation of the method The evaluation resulted in a recommendation that PG stability classification for regulatory applications at SRS should be based on measurements of the standard deviation of the vertical component of wind direction fluctuations, {sigma}{sub e}, collected from the 61-m level of the SRS meteorological towers, and processed in full accordance with EPA-454/R-99-005 (EPA, 2000). This approach provides a direct measurement that is fundamental to diffusion and captures explicitly the turbulence generated by both mechanical and buoyant forces over the characteristic surface (forested) of SRS. Furthermore, due to the potentially significant enhancement of horizontal fluctuations in wind direction from the occurrence of meander at night, the use of {sigma}{sub e} will ensure a reasonably conservative estimate of PG stability class for use in dispersion models that base diffusion calculations on a single value of PG stability class. Furthermore, meteorological data bases used as input for MACCS2 calculations should contain hourly data for five consecutive annual periods from the most recent 10 years.

  2. Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

  3. International comparison of computer codes for modelling the dispersion and transfer of tritium released to the atmosphere

    International Nuclear Information System (INIS)

    Computer codes for modelling the dispersion and transfer of tritium released to the atmosphere were compared. The codes originated from Canada, the United States, Sweden and Japan. The comparisons include acute and chronic emissions of tritiated water vapour or elemental tritium from a hypothetical nuclear facility. Individual and collective doses to the population within 100 km of the site were calculated. The discrepancies among the code predictions were about one order of magnitude for the HTO emissions but were significantly more varied for the HT emissions. Codes that did not account for HT to HTO conversion and cycling of tritium in the environment predicted doses that were several orders of magnitude less than codes that incorporate this feature into the model

  4. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

    Directory of Open Access Journals (Sweden)

    G. Katata

    2014-06-01

    Full Text Available Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1 accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information, and simulations from the oceanic dispersion model SEA-GEARN-FDM, both developed by the authors. A sophisticated deposition scheme, which deals with dry and fogwater depositions, cloud condensation nuclei (CCN activation and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging for radioactive iodine gas (I2 and CH3I and other particles (CsI, Cs, and Te, was incorporated into WSPEEDI-II to improve the surface deposition calculations. The fallout to the ocean surface calculated by WSPEEDI-II was used as input data for the SEA-GEARN-FDM calculations. Reverse and inverse source-term estimation methods based on coupling the simulations from both models was adopted using air dose rates and concentrations, and sea surface concentrations. The results revealed that the major releases of radionuclides due to FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, the morning of 13 March after the venting event at Unit 3, midnight of 14 March when the SRV (Safely Relief Valve at Unit 2 was opened three times, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal

  5. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

    Science.gov (United States)

    Katata, G.; Chino, M.; Kobayashi, T.; Terada, H.; Ota, M.; Nagai, H.; Kajino, M.; Draxler, R.; Hort, M. C.; Malo, A.; Torii, T.; Sanada, Y.

    2014-06-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information), and simulations from the oceanic dispersion model SEA-GEARN-FDM, both developed by the authors. A sophisticated deposition scheme, which deals with dry and fogwater depositions, cloud condensation nuclei (CCN) activation and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The fallout to the ocean surface calculated by WSPEEDI-II was used as input data for the SEA-GEARN-FDM calculations. Reverse and inverse source-term estimation methods based on coupling the simulations from both models was adopted using air dose rates and concentrations, and sea surface concentrations. The results revealed that the major releases of radionuclides due to FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, the morning of 13 March after the venting event at Unit 3, midnight of 14 March when the SRV (Safely Relief Valve) at Unit 2 was opened three times, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of

  6. A comparative sensitivity analysis focused on wet deposition models for the Fukushima and Chernobyl atmospheric dispersion events

    Science.gov (United States)

    Quérel, Arnaud; Roustan, Yelva; Quélo, Denis; Bocquet, Marc; Winiarek, Victor

    2014-05-01

    In order to model the transport of radionuclides bound to atmospheric particles and the ground contamination at the synoptic scale, the wet deposition is a crucial point. Usually, the wet deposition is divided in two different mechanisms, the below-cloud scavenging (washout) and the in-cloud scavenging (rainout). Since the micro-physics of both deposition processes is not well known yet, the modeling of the wet deposition of particles at the synoptic scale is uncertain and difficult to validate. This leads to an abundance of wet deposition models, none of them being fully adequate. The existing models of particle scavenging can be distinguished by the nature and the number of physical parameters they rely on. For instance the scavenging coefficient variability can be determined only by the rainfall intensity or take into account the rainfall intensity and the particle size distribution. Beyond their intrinsic formulations, the deposition models are sensitive to the input data necessary to use them, cloud height for instance. Finally, the simulated ground deposition is more or less sensitive to the choices of the overall-models involved in the atmospheric transport of particles and the meteorology in general. For accidental atmospheric releases, the uncertainties linked to the source-term are for instance crucial, what justifies the use of different ones in the study. The Polyphemus air quality system is used to perform the simulations of the radioactive dispersion, considering Caesium-137 as particulate matter for the accidental releases from the Fukushima and Chernobyl nuclear power plants. In this study, two different approaches are used. In the first one, the influence of the different components taking part in the scavenging modeling are confronted separately (whether the scavenging models or the overall models). The second approach is a global sensitivity analysis computed both on the Chernobyl and Fukushima cases. It relies on simulations performed with

  7. Dutch distribution zones of stable iodine tablets based on atmospheric dispersion modelling of accidental releases from nuclear power plants

    International Nuclear Information System (INIS)

    Rapid administration of stable iodine is essential for the saturation and subsequent protection of the thyroid gland against the potential harm caused by radio-iodines. This paper proposes the Dutch risk analysis that uses an atmospheric dispersion model to calculate the size of the zones around nuclear power plants where radiological thyroid doses for children might be sufficiently high to warrant iodine administration. Dose calculations for possible releases from the nuclear power plants of Borssele (The Netherlands), Doel (Belgium) and Emsland (Germany) are based on two scenarios in combination with a 1-y set of authentic, high-resolution meteorological data. The dimensions of the circular zones were defined for each nuclear power plant. In these zones, with a radius up to 50 km, distribution of stable iodine tablets is advised. (authors)

  8. Some meteorological parameters for atmospheric dispersion modelling at Lucas Heights, NSW, Australia, 1975 to 1983

    International Nuclear Information System (INIS)

    Meteorological data collected in the years 1975 to 1983 at the AAEC's Research Establishment at Lucas Heights, New South Wales, Australia have been summarised. Wind speed, direction and turbulence trace types from 7 and 49 m, temperature difference between 9 and 49 m, ambient temperature and precipitation rates have been extracted as 30 minute averages. Seasonal wind speed and direction roses are summarised for 7 and 49 m together with wind direction persistence statistics which are relevant to short-term (accident) releases of atmospheric pollutants. A 'split-sigma' approach has been adopted for definition of the atmospheric stability categories: a 'turbulence' method using the wind direction turbulence trace types for the horizontal diffusion category; and the US Nuclear Regulatory Commission temperature gradient criteria are combined with Smith's 1972 scheme for the vertical diffusion estimates. Statistics on 10, 50 and 90 per cent probability and average wind speeds and atmospheric stabilities are also analysed. An extensive data summary is included

  9. Temporal variations in atmospheric dispersion at Hanford

    International Nuclear Information System (INIS)

    Climatological data are frequently used to estimate atmospheric dispersion factors for historical periods and for future releases for which adequate meteorological data are unavailable. This practice routinely leads to questions concerning the representativeness of data used. The work described here was performed to provide a basis for answering these questions at the U.S. Department of Energy's Hanford Site in eastern Washington. Atmospheric transport and diffusion near Hanford have been examined using a Lagrangian puff dispersion model and hourly meteorological data from the Hanford Meteorological Station and a network of 24 surface wind stations for a 5-yr period. Average normalized monthly concentrations were computed at 2.5-km intervals on a 31 by 31 grid from January 1983 through 1987, assuming an elevated release in the 200-East Area. Monthly average concentrations were used to determine 5-yr mean pattern and monthly mean patterns and the interannual variability about each pattern. Intra-annual and diurnal variations in dispersion factors are examined for six locations near Hanford

  10. Atmospheric dispersion in nuclear power plant siting

    International Nuclear Information System (INIS)

    The atmosphere is an important pathway for the transport of radioactive releases from a nuclear power plant to the environment and thereby to man. It is necessary therefore to have adequate information about this pathway in order to estimate the dispersion of radioactive releases to the population in the region and thus be able to assess the radiological impact on man. The present Guide describes the meteorological phenomena and mechanisms involved in the dispersion of the released effluents in the atmosphere, discusses the methods which may be used to calculate the concentration and deposition in the region, specifies the data needed for input to these models, states the characteristics of the requisite instrumentation and data analysis systems and discusses certain related topics. Methods are presented for estimating concentration for short and long periods of emission over a wide range of types of radioactive releases. The evaluation of dose to individuals and population, given the concentration, is dealt with in national and international publications. It has been customary in the safety analysis of nuclear power plants to prepare dispersion estimates with different degrees of emphasis and various accuracy requirements at the stages of (a) site survey, (b) site evaluation, and (c) operation of the plant, and for accident contingency planning. Recommendations given in the present Guide generally apply to a distance of up to about 10 km depending upon the complexity of the terrain. The extension to longer distances may be made with caution and to the satisfaction of the regulatory authority

  11. Atmospheric dispersion of an elevated release in a rural environment: Comparison between field SF 6 tracer measurements and computations of Briggs and ADMS models

    Science.gov (United States)

    Connan, O.; Leroy, C.; Derkx, F.; Maro, D.; Hébert, D.; Roupsard, P.; Rozet, M.

    2011-12-01

    The French Institute for Radiological Protection and Nuclear Safety (IRSN), in collaboration with VEOLIA (French environmental services company), conducted experimental campaigns to study atmospheric dispersion around an Energy Recycling Unit (EUR). The objectives were to study dispersion for an elevated release in a rural environment and to compare results with those of models. The atmospheric dispersion was studied by SF 6 tracer injection into a 40 m high stack. Maximum values of experimental Atmospheric Transfer Coefficients (ATC max) and horizontal dispersion standard deviations ( σh) were compared to predictions from a first generation Briggs gaussian model as well as results from the latest generation ADMS 4.1 gaussian model. In neutral atmospheric conditions, the Briggs and ADMS models are in good agreement with experimental data in terms of ATC and σh. In unstable condition, for σh, both ADMS and Briggs models slightly overestimate the data for winter and summer conditions. In unstable conditions, ADMS and Briggs models overestimated ATC max. The statistical evaluation of the models versus experimental data shows neither models ever meets all of the criteria for good performance. However, statistical evaluation indicates that the ADMS model is more suitable for neutral condition, and that the Briggs model is more reliable for summer unstable conditions.

  12. Atmospheric Dispersion Modeling of 137Cs generated from Nuclear Spent Fuel under Hypothetic Accidental Condition in the BNPP Area

    Science.gov (United States)

    Lee, Jongkuk; Lee, Kwan-Hee; Yook, Daesik; Kim, Sung Il; Lee, Byung Soo

    2016-04-01

    This study presents the results of atmosphere dispersion modeling using CALPUFF code that are based on computational simulation to evaluate the environmental characteristics of the Barakah nuclear power plant (BNPP) in west area of UAE. According to meteorological data analysis (2012~2013), the winds from the north(7.68%) and west(9.05%) including NNW(41.63%), NW(28.55%), and WNW(6.31%) winds accounted for more than 90% of the wind directions. East(0.2%) and south(0.6%) direction wind, including ESE(0.31%), SE(0.38%), and SSE(0.38%) were rarely distributed during the simulation period. Seasonal effects were not showed. However, a discrepancy in the tendency between daytime and night-time was observed. Approximately 87% of the wind speed was distributed below 5.4m/s (17%, 47% and 23% between the speeds of 0.5-1.8m/s 1.8-3.3m/s and 3.3-5.4m/s, respectively) during the annual period. Seasonal wind speed distribution results presented very similar pattern of annual distribution. Wind speed distribution of day and night, on the other hand, had a discrepancy with annual modeling results than seasonal distribution in some sections. The results for high wind speed (more than 10.8m/s) showed that this wind blew from the west. This high wind speed is known locally as the 'Shamal', which occurs rarely, lasting one or two days with the strongest winds experienced in association with gust fronts and thunderstorms. Six variations of cesium-137 (137Cs) dispersion test were simulated under hypothetic severe accidental condition. The 137Cs dispersion was strongly influenced by the direction and speed of the main wind. From the test cases, east-south area of the BNPP site was mainly influenced by 137Cs dispersion. A virtual receptor was set and calculated for observation of the 137Cs movement and accumulation. Surface roughness tests were performed for the analysis of topographic conditions. According to the surface condition, there are various surface roughness length. Four types

  13. Implementation of a model of atmospheric dispersion and dose calculation in the release of radioactive effluents in the Nuclear Centre

    International Nuclear Information System (INIS)

    In the present thesis, the software DERA (Dispersion of Radioactive Effluents into the Atmosphere) was developed in order to calculate the equivalent dose, external and internal, associated with the release of radioactive effluents into the atmosphere from a nuclear facility. The software describes such emissions in normal operation, and not considering the exceptional situations such as accidents. Several tools were integrated for describing the dispersion of radioactive effluents using site meteorological information (average speed and wind direction and the stability profile). Starting with the calculation of the concentration of the effluent as a function of position, DERA estimates equivalent doses using a set of EPA s and ICRP s coefficients. The software contains a module that integrates a database with these coefficients for a set of 825 different radioisotopes and uses the Gaussian method to calculate the effluents dispersion. This work analyzes how adequate is the Gaussian model to describe emissions type -puff-. Chapter 4 concludes, on the basis of a comparison of the recommended correlations of emissions type -puff-, that under certain conditions (in particular with intermittent emissions) it is possible to perform an adequate description using the Gaussian model. The dispersion coefficients (σy and σz), that using the Gaussian model, were obtained from different correlations given in the literature. Also in Chapter 5 is presented the construction of a particular correlation using Lagrange polynomials, which takes information from the Pasquill-Gifford-Turner curves (PGT). This work also contains a state of the art about the coefficients that relate the concentration with the equivalent dose. This topic is discussed in Chapter 6, including a brief description of the biological-compartmental models developed by the ICRP. The software s development was performed using the programming language Python 2.7, for the Windows operating system (the XP version

  14. Ensemble atmospheric dispersion calculations for decision support systems

    International Nuclear Information System (INIS)

    This document describes two approaches to long-range atmospheric dispersion of pollutants based on the ensemble concept. In the first part of the report some experiences related to the exercises undertaken under the ENSEMBLE project of the European Union are presented. The second part is devoted to the implementation of mesoscale numerical prediction models RAMS and atmospheric dispersion model HYPACT on Beowulf cluster and theirs usage for ensemble forecasting and long range atmospheric ensemble dispersion calculations based on available meteorological data from NCEO, NOAA (USA). (author)

  15. Detailed source term estimation of atmospheric release during the Fukushima Dai-ichi nuclear power plant accident by coupling atmospheric and oceanic dispersion models

    Science.gov (United States)

    Katata, Genki; Chino, Masamichi; Terada, Hiroaki; Kobayashi, Takuya; Ota, Masakazu; Nagai, Haruyasu; Kajino, Mizuo

    2014-05-01

    Temporal variations of release amounts of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident and their dispersion process are essential to evaluate the environmental impacts and resultant radiological doses to the public. Here, we estimated a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data and coupling atmospheric and oceanic dispersion simulations by WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN developed by the authors. New schemes for wet, dry, and fog depositions of radioactive iodine gas (I2 and CH3I) and other particles (I-131, Te-132, Cs-137, and Cs-134) were incorporated into WSPEEDI-II. The deposition calculated by WSPEEDI-II was used as input data of ocean dispersion calculations by SEA-GEARN. The reverse estimation method based on the simulation by both models assuming unit release rate (1 Bq h-1) was adopted to estimate the source term at the FNPP1 using air dose rate, and air sea surface concentrations. The results suggested that the major release of radionuclides from the FNPP1 occurred in the following periods during March 2011: afternoon on the 12th when the venting and hydrogen explosion occurred at Unit 1, morning on the 13th after the venting event at Unit 3, midnight on the 14th when several openings of SRV (steam relief valve) were conducted at Unit 2, morning and night on the 15th, and morning on the 16th. The modified WSPEEDI-II using the newly estimated source term well reproduced local and regional patterns of air dose rate and surface deposition of I-131 and Cs-137 obtained by airborne observations. Our dispersion simulations also revealed that the highest radioactive contamination areas around FNPP1 were created from 15th to 16th March by complicated interactions among rainfall (wet deposition), plume movements, and phase properties (gas or particle) of I-131 and release rates

  16. Atmospheric dispersion of argon-41 from anuclear research reactor: measurement and modeling of plume geometry and gamma radiation field

    DEFF Research Database (Denmark)

    Lauritzen, Bent; Astrup, Poul; Drews, Martin; Jørgensen, Hans; Mikkelsen, Torben; Thykier-Nielsen, Søren; Aage, Helle Karina; Korsbech, Uffe C C; Bargholz, Kim; Rojas-Palma, Carlos; Van Ammel, Raf

    2003-01-01

    An atmospheric dispersion experiment was conducted using a visible tracer along with the routine release of argon-41 from the BR1 research reactor in Mol, Belgium. Simultaneous measurements of plume geometry and radiation fields for argon-41 decay were performed as well as measurements of the argon...

  17. Nuclear risk from atmospheric dispersion in Northern Europe - Summary Report

    OpenAIRE

    Lauritzen, Bent

    2011-01-01

    The objective of the NordRisk II project has been to derive practical means for assessing the risks from long-range atmospheric dispersion of radioac-tive materials. An atlas over different atmospheric dispersion and deposi-tion scenarios has been developed using historical numerical weather pre-diction (NWP) model data. The NWP model data covers three years span-ning the climate variability associated with the North Atlantic Oscillation, and the atlas considers radioactive releases from 16 r...

  18. Data assimilation on atmospheric dispersion of radioactive materials

    DEFF Research Database (Denmark)

    Drews, Martin

    2006-01-01

    During a nuclear accident in which radionuclides are released to the atmosphere, off-site dose assessment using atmospheric dispersion models play an important role in facilitating optimized interventions, i.e. for mitigating the radiological consequences. By using data assimilation methods......, radiological observations, e.g. dose rate measurements, can be used to improve these model predictions and to obtain real-time estimates of the atmospheric dispersion parameters. This thesis examines data assimilation in the context of atmospheric dispersion of radioactive materials. In particular, it presents...... greatly improved dose rate assessment. The Kalman filter method is found to be computationally efficient and therefore has the potential of becoming an efficient operational assimilation tool for nuclear emergency management. Empirical dispersion data are crucial in order to evaluate dose rate models and...

  19. Contaminant dispersion prediction and source estimation with integrated Gaussian-machine learning network model for point source emission in atmosphere.

    Science.gov (United States)

    Ma, Denglong; Zhang, Zaoxiao

    2016-07-01

    Gas dispersion model is important for predicting the gas concentrations when contaminant gas leakage occurs. Intelligent network models such as radial basis function (RBF), back propagation (BP) neural network and support vector machine (SVM) model can be used for gas dispersion prediction. However, the prediction results from these network models with too many inputs based on original monitoring parameters are not in good agreement with the experimental data. Then, a new series of machine learning algorithms (MLA) models combined classic Gaussian model with MLA algorithm has been presented. The prediction results from new models are improved greatly. Among these models, Gaussian-SVM model performs best and its computation time is close to that of classic Gaussian dispersion model. Finally, Gaussian-MLA models were applied to identifying the emission source parameters with the particle swarm optimization (PSO) method. The estimation performance of PSO with Gaussian-MLA is better than that with Gaussian, Lagrangian stochastic (LS) dispersion model and network models based on original monitoring parameters. Hence, the new prediction model based on Gaussian-MLA is potentially a good method to predict contaminant gas dispersion as well as a good forward model in emission source parameters identification problem. PMID:27035273

  20. Summary of 19. NATO/CCMS international technical meeting (ITM) round table discussion on the harmonization of atmospheric dispersion models

    International Nuclear Information System (INIS)

    A Round Table discussion was held at the 19th NATO/CCMS Conference on Atmospheric Dispersion with participation of approximately 50 scientists involved with various aspects of air quality assessment from over 15 countries. The premise of discussion was there is a need within the European Countries to provide a basis for developing an approach towards harmonization of air quality modeling. The term ''harmonization'' was used mostly in the sense that for the same input a simulation model would compute the same output. Concern was expressed that this usage was overly simplistic, prohibitively restrictive and counterproductive. The main benefits of achieving harmonization were 1) proper use of available meteorological data and 2) consistent treatment of source impacts throughout the European Community. The challenge before the European Community is to resolve in a realistic manner the problem of assessing environmental impacts in a manner that is fair throughout the European Community and proper within the scientific community. The resolution will involve compromises between 'being fair' and 'being state-of-the-science'. Accuracy and realism may be willingly sacrificed in order to achieve fairness. Developing consensus on how and what is to be achieved in the process of harmonization will involve difficult value judgments. But the consensus process should be encouraged given the significant and worthwhile benefits. (au)

  1. Development of local-scale high-resolution atmospheric dispersion model using large-eddy simulation. Part 3: turbulent flow and plume dispersion in building arrays

    Czech Academy of Sciences Publication Activity Database

    Nakayama, H.; Jurčáková, Klára; Nagai, H.

    2013-01-01

    Roč. 50, č. 5 (2013), s. 503-519. ISSN 0022-3131 Institutional support: RVO:61388998 Keywords : local -scale high-resolution dispersion model * nuclear emergency response system * large-eddy simulation * spatially developing turbulent boundary layer flow Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.452, year: 2013

  2. Application of a one-dimensional Gaussian model for describing the atmospheric dispersion of Xe-133 in the area of the Fessenheim nuclear power station

    International Nuclear Information System (INIS)

    In the area on the right bank of the Rhine river, around the Fessenheim nuclear power plant, two measuring stations have been installed for measuring the weakly mean atmospheric xenon-133 activity between mid-year 1983 and the end of 1984. The mean hight of immissions at the stations that were situated near the main atmospheric dispersion direction allowed a dispersion study to be made. Expected values of immission have been calculated by means of a one-dimensional Gaussian model, taking into account the known mean source strength. The radiation balance, cloud amount, or cloud amount/global radiation, and the wind velocity are the parameters used for determining atmospheric stability. They have been found to be equally good. The agreement between measured data and calculated data obtained by the simple model and expressed in weakly average data is found to be satisfactory. (orig./PW)

  3. Influence of the diagnostic wind field model on the results of calculation of the microscale atmospheric dispersion in moderately complex terrain

    Science.gov (United States)

    Kovalets, Ivan V.; Korolevych, Vladimir Y.; Khalchenkov, Alexander V.; Ievdin, Ievgen A.; Zheleznyak, Mark J.; Andronopoulos, Spyros

    2013-11-01

    The impact of diagnostic wind field model on the results of calculation of microscale atmospheric dispersion in moderately complex terrain conditions was investigated. The extensive radiological and meteorological data set collected at the site of the research reactor of the Chalk River Laboratories (CRL) in Canada had been compared with the results of calculations of the Local Scale Model Chain of the EU nuclear emergency response system JRODOS. The diagnostic wind field model based on divergence minimizing procedure and the atmospheric dispersion model RIMPUFF were used in calculations. Taking into account complex topography features with the use of diagnostic wind field model improved the results of calculations. For certain months, the level of improvement of the normalized mean squared error reached the factor of 2. For the whole simulation period (January-July, 2007) the level of improvement by taking into account terrain features with the diagnostic wind field model was about 9%. The use of diagnostic wind field model also significantly improved the fractional bias of the calculated results. Physical analysis of the selected cases of atmospheric dispersion at the CRL site had been performed.

  4. A costal dispersion model

    International Nuclear Information System (INIS)

    A dispersion model to be used off costal waters has been developed. The model has been applied to describe the migration of radionuclides in the Baltic sea. A summary of the results is presented here. (K.A.E)

  5. Dispersion, deposition and resuspension of atmospheric contaminants

    International Nuclear Information System (INIS)

    The following topics are discussed: dry deposition, oil shale fugitive air emissions, particle resuspension and translocation, theoretical studies and applications, and processing of emissions by clouds and precipitation. The concentration of contaminant species in air is governed by the rate of input from sources, the rate of dilution or dispersion as a result of air turbulence, and the rate of removal to the surface by wet and dry deposition processes. Once on the surface, contaminants also may be resuspended, depending on meteorological and surface conditions. An understanding of these processes is necessary for accurate prediction of exposures of hazardous or harmful contaminants to humans, animals, and crops. In the field, plume dispersion and plume depletion by dry deposition were studied by the use of tracers. Dry deposition was investigated for particles of both respiration and inhalation interest. Complementary dry deposition studies of particles to rock canopies were conducted under controlled conditions in a wind tunnel. Because of increasing concern about hazardous, organic gases in the atmosphere some limited investigations of the dry deposition of nitrobenzene to a lichen mat were conducted in a stirred chamber. Resuspension was also studied using tracers and contaminated surfaces and in the wind tunnel. The objective of the resuspension studies was to develop and verify models for predicting the airborne concentrations of contaminants over areas with surface contamination, develop resuspension rate predictors for downwind transport, and develop predictors for resuspension input to the food chain. These models will be of particular relevance to the evaluation of deposition and resuspension of both radionuclides and chemical contaminants

  6. A study of atmospheric dispersion of radionuclides at a coastal site using a modified Gaussian model and a mesoscale sea breeze model

    Science.gov (United States)

    Venkatesan, R.; Mathiyarasu, R.; Somayaji, K. M.

    Ground level concentration and sky-shine dose due to radioactive emissions from a nuclear power plant at a coastal site have been estimated using the standard Gaussian Plume Model (GPM) and the modified GPM suggested by Misra (Atmospheric Environment 14 (1980) 397), which incorporates fumigation effect under sea breeze condition. The difference in results between these two models is analysed in order to understand their significance and errors that would occur if proper choice were not made. Radioactive sky-shine dose from 41Ar, emitted from a 100 m stack of the nuclear plant is continuously recorded by environmental gamma dose monitors and the data is used to validate the modified GPM. It is observed that the dose values increase by a factor of about 2 times than those of the standard GPM estimates, up to a downwind distance of 6 km during sea breeze hours. In order to examine the dispersion of radioactive effluents in the mesoscale range, a sea breeze model coupled with a particle dispersion model is used. The deposited activity, thyroid dose and sky-shine radioactive dose are simulated for a range of 30 km. In this range, the plume is found to deviate from its straight-line trajectory, as otherwise assumed in GPM. A secondary maximum in the concentration and the sky-shine dose is also observed in the model results. These results are quite significant in realistically estimating the area affected under any unlikely event of an accidental release of radioactivity.

  7. Calculation of radiation doses due to release of 137Cs and 131I using atmospheric dispersion and dose calculation models

    International Nuclear Information System (INIS)

    Full text: With the growing need of energy all over the world there is no doubt that nuclear energy will be an important alternative. Nuclear energy is not only a good alternative energy source but also is getting more safe. In contrary to fossil fuels nuclear energy does not produce green house gases. With all adventages of nuclear energy, the safety of nuclear power plants must be taken into care. From the radiological point of view the atmospheric dispersion of radionuclides and radiation dose calculations in case of a reactor accident is important. This study investigates the deposition and air concentration of 137Cs and 131I radionuclides and the radiation doses exposed to people living in different cities in Turkey after Chernobyl nuclear reactor accident. WRF results and HYSPLIT results were compared with observation data and the 'Atlas on the cesium deposition across Europe' that published by European Commission respectively. Both WRF and HYSPLIT results were consistent with reference data. (author)

  8. Numerical methods of estimating the dispersion of radionuclides in atmosphere

    International Nuclear Information System (INIS)

    Full text: The paper presents the method of dispersion calculation, witch can be applied for the DLE calculation. This is necessary to ensure a secure performance of the Experimental Pilot Plant for Tritium and Deuterium Separation (using the technology for detritiation based upon isotope catalytic exchange between tritiated heavy water and deuterium followed by cryogenic distillation of the hydrogen isotopes). For the calculation of the dispersion of radioactivity effluents in the atmosphere, at a given distance between source and receiver, the Gaussian mathematical model was used. This model is currently applied for estimating the long-term results of dispersion in case of continuous or intermittent emissions as basic information for long-term radioprotection measures for areas of the order of kilometres from the source. We have considered intermittent or continuous emissions of intensity lower than 1% per day relative to the annual emission. It is supposed that the radioactive material released into environment presents a gaussian dispersion both in horizontal and vertical plan. The local dispersion parameters could be determined directly with turbulence measurements or indirectly by determination of atmospheric stability. Weather parameters for characterizing the atmospheric dispersion include: - direction of wind relative to the source; - the speed of the wind at the height of emission; - parameters of dispersion to different distances, depending on the atmospheric turbulence which characterizes the mixing of radioactive materials in the atmosphere; - atmospheric stability range; - the height of mixture stratum; - the type and intensity of precipitations. The choice of the most adequate version of Gaussian model depends on the relation among the height where effluent emission is in progress, H (m), and the height at which the buildings influence the air motion, HB (m). There were defined three zones of distinct dispersion. This zones can have variable lengths

  9. The radiological consequences of notional accidental releases of radioactivity from fast breeder reactors: sensitivity to the choice of atmospheric dispersion model

    International Nuclear Information System (INIS)

    The radiological consequences of a wide range of notional accidental releases from a 1300 MW(e) LMFBR were assessed in a study published in 1977 (NRPB - R53). In that study representative values were in general adopted for each of the important parameters while recognising that in reality they could vary considerably. The present study is concerned with the sensitivity of the predicted consequences to the choice of atmospheric dispersion models. A comparison is made of the air concentrations predicted by a number of atmospheric models (which have found broad application) for releases of activity in selected meteorological conditions. The implications, in terms of the radiological consequences of particular releases, of differences in the air concentrations predicted by the respective models are assessed semi-quantitatively. In general the radiological consequences are shown to be relatively insensitive to the choice of atmospheric dispersion model. This is particularly so for the incidence of late biological effects; for early biological effects the sensitivity is more pronounced although of the models considered, that adopted in the initial study would yield results at the upper end of the predicted range. (author)

  10. Dispersion modeling of atmospheric contaminants in the Angra Nuclear Power Plant using LES and a new model for the CBL growth

    International Nuclear Information System (INIS)

    In the present work we report a comparison between experimental data and GILTT approach to simulate radioactive contaminant dispersion in the Atmospheric Boundary Layer using micrometeorological parameters generated by LES (Large Eddy Simulation) in the area around the Angra dos Reis Nuclear Power Plant. Furthermore, starting from the evolution equation for the turbulent energy density spectrum (EDS), we develop a new model for the growth of the turbulence in Convective Boundary Layer (CBL). We apply dimensional analysis to parameterize the unknown inertial transport and convective source term in the dynamic equation for the three-dimensional (3-D) spectrum. The non linear integro-differential equation is solved by Adomian decomposition method. The one-dimensional vertical spectrum is derived from the 3-D spectrum, employing a weight function. This allows us to select the magnitude of the vertical spectral component for the construction of the growing 3-D. Using the micrometeorological parameters generated by LES, for the first time, we employ the vertical component of the energy spectrum to calculate the eddy diffusivity (required in dispersion models). This new eddy diffusivity is used in the simulations of the ground-level concentrations considering experimental data of the Nuclear Power Plant. (author)

  11. A comparison of models to assess the atmospheric dispersion of resuspended radionuclides on the Nevada Test Site

    International Nuclear Information System (INIS)

    A study of computer codes was made to determine the suitability of their use for modeling radionuclide dispersion from attachment to fugitive dust at the GMX safety shot area of the Nevada Test site. Two codes, the Industrial Source Complex 2 Long Term Model (ISCLT2) and the Fugitive Dust Model (FDM), were subsequently chosen to model the GMX site. Dose calculations were performed using the output values generated by the computer codes. The concentration values produced by the two codes were within a factor of two of each other and were not significantly different. The FDM, however, was felt to be a more useful code for use in calculating doses caused by attachment to fugitive dust

  12. The European tracer experiment ETEX: a real-time long range atmospheric dispersion model exercise in different weather conditions

    International Nuclear Information System (INIS)

    Two long-range tracer experiments were conducted. An inert, non-depositing tracer was being released at Rennes in France for 12 hours. The 168 sampling ground stations were run by the National Meteorological Services. Twenty-four institutions took part in the real-time forecasting of the cloud evolution using 28 long-range dispersion models. The horizontal projection of the cloud evolution over Europe was combined with real-time aerial chemical analysis. The results of the comparison indicate that a limited group of models (7-8) were capable of obtaining a good reproduction of the cloud movement throughout Europe for the first release. Large differences were, however, found in the predicted tracer concentration at a particular location. For the second release, there were large differences between the measured and calculated cloud, particularly after a front passage, which indicates that some efforts have still to be spent before consensus on the model reliability is achieved. (P.A.)

  13. Some aspects of atmospheric dispersion in the stratified atmospheric boundary layer over homogeneous terrain

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik

    1999-01-01

    the Gaussian plume model concept with the spread parameters described in terms of the Pasquill stability classification or Monin-Obukhov similarity relationships are used. Other model types are Lagrangian particle models which also are parameterized in terms of Monin-Obukhov similarity relationships....... The applied models describe adequately the dispersion process in a weakly stable atmosphere, but fail during very stable atmospheric conditions. This suggests that Monin-Obukhov similarity theory is an adequate tool for the parameterization of the input parameters to atmospheric dispersion models...... during weakly stable conditions, but that more detailed parameterisations including other physical processes than those covered by the Monin-Obukhov theory should be developed for the very stable atmosphere....

  14. Delayed shear enhancement in mesoscale atmospheric dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Moran, M.D. [Atmospheric Environment Service, Ontario (Canada); Pielke, R.A. [Colorado State Univ., Fort Collins, CO (United States)

    1994-12-31

    Mesoscale atmospheric dispersion (MAD) is more complicated than smaller-scale dispersion because the mean wind field can no longer be considered steady or horizontally homogeneous over mesoscale time and space scales. Wind shear also plays a much more important role on the mesoscale: horizontal dispersion can be enhanced and often dominated by vertical wind shear on these scales through the interaction of horizontal differential advection and vertical mixing. Just over 30 years ago, Pasquill suggested that this interaction need not be simultaneous and that the combination of differential horizontal advection with delayed or subsequent vertical mixing could maintain effective horizontal diffusion in spite of temporal or spatial reductions in boundary-layer turbulence intensity. This two-step mechanism has not received much attention since then, but a recent analysis of observations from and numerical simulations of two mesoscale tracer experiments suggests that delayed shear enhancement can play an important role in MAD. This paper presents an overview of this analysis, with particular emphasis on the influence of resolvable vertical shear on MAD in these two case studies and the contributions made by delayed shear enhancement.

  15. Short-range atmospheric dispersion of carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Cortis, A.; Oldenburg, C.M.

    2009-11-01

    We present a numerical study aimed at quantifying the effects of concentration-dependent density on the spread of a seeping plume of CO{sub 2} into the atmosphere such as could arise from a leaking geologic carbon sequestration site. Results of numerical models can be used to supplement field monitoring estimates of CO{sub 2} seepage flux by modelling transport and dispersion between the source emission and concentration-measurement points. We focus on modelling CO{sub 2} seepage dispersion over relatively short distances where density effects are likely to be important. We model dense gas dispersion using the steady-state Reynolds-averaged Navier-Stokes equations with density dependence in the gravity term. Results for a two-dimensional system show that a density dependence emerges at higher fluxes than prior estimates. A universal scaling relation is derived that allows estimation of the flux from concentrations measured downwind and vice versa.

  16. A study on mesoscale atmospheric dispersion of radioactive particles released from nuclear power plants

    International Nuclear Information System (INIS)

    A three dimensional sea-land breeze model and lagrangian particle dispersion model have been employed for the study on the mesoscale atmospheric dispersion of radioactive materials released from Wolsung NPPs. In this study, atmospheric dispersion simulations are carried out under two synoptic weather conditions: the geostrophic flow is a weak northerly wind (CASE 1) and a strong northerly wind (CASE 2) on a clear day in spring. The results show that atmospheric dispersion is affected by sea-land breeze and the recirculation of particles by the change of wind direction between sea breeze and land breeze plays an important role in atmospheric concentration distribution of radioactive materials

  17. A computational model for the rise and dispersion of wind-blown, buoyancy-driven plumes—II. Linearly stratified atmosphere

    Science.gov (United States)

    Zhang, Xiaoming; Ghoniem, Ahmed F.

    A multi-dimensional computational model of wind-blown, buoyancy-driven flows is applied to study the effect of atmospheric stratification on the rise and dispersion of plumes. The model utilizes Lagrangian transport elements, distributed in the plane of the plume cross section normal to the wind direction, to caoture the evolution of the vorticity and density field, and another set of elements to model the dynamics in the atmosphere surrounding the plume. Solutions are obtained for a case in which atmospheric density changes linearly with height. Computational results show that, similar to the case of a neutrally stratified atmosphere, the plume acquires a kidney-shaped cross section which persists for a long distance downstream the source and may bifurcate into separate and distinct lumps. Baroclinic vortivity generated both along the plume boundary and in the surroundings is used to explain the origin of the distortion experienced by the plume and the inhibiting effect of a stratified atmosphere, respectively. The vorticity within the plume cross section forms two large-scale coherent eddies which are responsible for the plume motion and the entrainment. Prior to reaching the equilibrium height, the computed plume trajectory is found to follow the two-thirds law, when extended to include the initial plume size, reasonably well. Entrainment and added mass coefficients equal to 0.49 and 0.7 respectively, are obtained from the numerical results over a wide range of the buoyancy ratio, defined as the ratio between the plume buoyancy and the degree of background stratification. In the case of strong stratification, the plume trajectory shows weak, fast decaying oscillations around the equilibrium height.

  18. A computational model for the rise and dispersion of wind-blown, buoyancy-driven plumes—I. Neutrally stratified atmosphere

    Science.gov (United States)

    Zhang, Xiaoming; Ghoniem, Ahmed F.

    A multi-dimensional computational model for the rise and dispersion of a wind-blown, buoyancy-driven plume in a calm, neutrally stratified atmosphere is presented. Lagrangian numerical techniques, based on the extension of the vortex method to variable density flows, are used to solve the governing equations. The plume rise trajectory and the dispersion of its material in the crosswind plane are predicted. It is found that the computed trajectory agrees well with the two-thirds power law of a buoyancy-dominated plume, modified to include the effect of the initial plume size. The effect of small-scale atmospheric turbulence, modeled in terms of eddy viscosity, on the plume trajectory is found to be negligible. For all values of buoyancy Reynolds number, the plume cross-section exhibits a kidney-shaped pattern, as observed in laboratory and field experiments. This pattern is due to the formation of two counter-rotating vortices which develop as baroclinically generated vorticity rolls up on both sides of the plume cross-section. Results show that the plume rise can be described in terms of three distinct stages: a short acceleration stage, a long double-vortex stage, and a breakup stage. The induced velocity field and engulfment are dominated by the two large vortices. The effect of a flat terrain on the plume trajectory and dispersion is found to be very small. The equivalent radii of plumes with different initial cross-sectional aspect ratios increase at almost the same rate. A large aspect-ratio plume rises slower initially and then catches up with smaller aspect-ratio plumes in the breakup stage. The Boussinesq approximation is found to be valid if the ratio of the density perturation to the reference density is less than 0.1.

  19. Estimation of NH3 emissions from a naturally ventilated livestock farm using local-scale atmospheric dispersion modelling

    Directory of Open Access Journals (Sweden)

    P. Cellier

    2009-01-01

    Full Text Available Agricultural livestock represents the main source of ammonia (NH3 in Europe. In recent years, reduction policies have been applied to reduce NH3 emissions. In order to estimate the impacts of these policies, robust estimates of the emissions from the main sources, i.e. livestock farms are needed. In this paper, the NH3 emissions were estimated from a naturally ventilated livestock farm in Braunschweig, Germany during a joint field experiment of the GRAMINAE European project. An inference method was used with a Gaussian-3-D plume model and a local-scale dispersion and deposition model (FIDES-2-D. NH3 concentrations downwind of the source were used together with micrometeorological data to estimate the source strength over time. Mobile NH3 concentration measurements provided information on the spatial distribution of source strength. The estimated emission strength ranged between 6.0±0.17 kg NH3 d−1 (FIDES-2-D model and 9.2±0.7 kg NH3 d−1 (Gaussian model. These estimates were 94% and 63% of what was obtained using emission factors from the German national inventory (9.6 kg d−1 NH3. However, the FIDES-2-D approach was shown to be very sensitive to the source size, the roughness height and to whether deposition was taken into account downwind of the source. Accounting for deposition in FIDES-2-D gives a potential emission estimate of 11.7 kg NH3 d−1, showing that deposition can explain the observed difference. The daily pattern of the source was correlated with net radiation and with the temperature inside the animal houses. The daily pattern resulted from a combination of a temperature effect on the source concentration together with an effect of variations in free and forced convection of the building ventilation rate. Further development of the plume technique is especially relevant for naturally ventilated farms, since the variable ventilation rate makes other emission measurements difficult.

  20. Investigation of the interaction between sources and sinks of atmospheric ammonia in an upland landscape using a simplified dispersion-exchange model

    Science.gov (United States)

    Loubet, Benjamin; Milford, Celia; Sutton, Mark A.; Cellier, Pierre

    2001-10-01

    Exchange of atmospheric ammonia (NH3) with vegetation is characterized by the juxtaposition of sources and sinks at a landscape level. Such situations lead to a large fraction of the landscape being exposed to local advection effects that if not accounted for, introduce errors in standard micrometeorological measurements of NH3 exchange with the surface. In this study, a simplified dispersion - exchange model for NH3 (Flux Interpretation by Dispersion and Exchange over Short Range, FIDES) is evaluated and used to assess the advection fluxes at 260 m downwind of an isolated pasture, grazed with sheep, using the measurements of a classical three-point NH3 gradient system located on adjacent moorland. The method consists of fitting the measured and modeled concentration profile by adjusting at the same time the emission strength of the local source and the exchange rate of NH3 to the moorland area downwind. A local dispersion and surface exchange model such as FIDES has proved to be a valuable tool to estimate advection corrections, given sound estimates of background NH3 concentrations, source location, and standard meteorological parameters. According to the model results the advection fluxes at the moorland measurement site, at 1.0 m height and 260 m downwind of the grazed pasture, were positive. For 80% of the situations they ranged between 30% and 60% of the vertical flaxes. In stable conditions the advection fluxes were large and more sensitive to the surface exchange parameters. These results demonstrate that if not accounted for, advection fluxes may lead to a severe underestimate of the NH3 deposition to seminatural ecosystems, such as moorland, in the vicinity of ground level agricultural sources.

  1. Atmospheric dispersion modeling of hazardous air pollutant emissions from USDOE Oak Ridge Reservation Facilities. Volume 1, Independent Assessment conducted from April 1994 to December 1994

    International Nuclear Information System (INIS)

    Title 3 of the 1990 Clean Air Act (CAA) Amendments addresses the emissions of 189 hazardous air pollutants (HAPs) and mandates that EPA develop technology-based [Maximum Achievable Control Technology (MACT)] standards for the control of these pollutants from approximately 174 source categories. After implementation of technology-based standards, EPA is required to further evaluate ''residual risk'' from HAP emissions, and, if required, develop more stringent standards to protect human health and the environment with an ''adequate margin of safety''. Recognizing that EPA will be issuing risk-based regulations after MACT standards have been implemented, the US Department of Energy (DOE), Oak Ridge Operations Office (ORO) has conducted an evaluation of ambient air impacts of HAP emissions from its installations located on the Oak Ridge Reservation (ORR) near Oak Ridge, Tennessee. This report provides results of atmospheric dispersion modeling conducted to determine ambient air impacts of HAP emissions from facilities located on the ORR

  2. Nuclear risk from atmospheric dispersion in Northern Europe - Summary Report

    DEFF Research Database (Denmark)

    Lauritzen, Bent

    The objective of the NordRisk II project has been to derive practical means for assessing the risks from long-range atmospheric dispersion of radioac-tive materials. An atlas over different atmospheric dispersion and deposi-tion scenarios has been developed using historical numerical weather pre...

  3. Dispersion modelling after Chernobyl

    International Nuclear Information System (INIS)

    At the time of the Chernobyl accident, little was known about the magnitude and time pattern of the release from the damaged reactor. This paper describes the detective work done in the weeks following the accident to assess the release and its dispersal across Europe; also new calculations done since the USSR presentations in Vienna at the end of August 1986 and some estimates of longer term collective dose commitment are given. The MESOS computer model developed at Imperial College to simulate the dispersal of hypothetical accidental releases of important radionuclides, out to distances of several hundred kilometers, and estimate levels of contamination in the air and deposited on the ground, was adapted for real time use. Combined with meteorological data and measurements of radionuclides collected from miscellaneous sources across Europe, it was possible to estimate how much had been released. To conclude, some general remarks are made about the implications of the Chernobyl accident for technical support in emergency procedures for any future nuclear accident. (UK)

  4. Dense gas dispersion in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Morten

    1998-09-01

    Dense gas dispersion is characterized by buoyancy induced gravity currents and reduction of the vertical mixing. Liquefied gas releases from industrial accidents are cold because of the heat of evaporation which determines the density for a given concentration and physical properties. The temperature deficit is moderated by the heat flux from the ground, and this convection is an additional source of turbulence which affects the mixing. A simple model as the soil heat flux is used to estimate the ability of the ground to sustain the heat flux during release. The initial enthalpy, release rate, initial entrainment and momentum are discussed for generic source types and the interaction with obstacles is considered. In the MTH project BA experiments source with and without momentum were applied. The continuously released propane gas passed a two-dimensional removable obstacle perpendicular to the wind direction. Ground-level gas concentrations and vertical profiles of concentration, temperature, wind speed and turbulence were measured in front of and behind the obstacle. Ultrasonic anemometers providing fast velocity and concentration signals were mounted at three levels on the masts. The observed turbulence was influenced by the stability and the initial momentum of the jet releases. Additional information were taken from the `Dessert tortoise` ammonia jet releases, from the `Fladis` experiment with transition from dense to passive dispersion, and from the `Thorney Island` continuous releases of isothermal freon mixtures. The heat flux was found to moderate the negative buoyancy in both the propane and ammonia experiments. The heat flux measurements are compared to an estimate by analogy with surface layer theory. (au) 41 tabs., 146 ills., 189 refs.

  5. Simulation of atmospheric dispersion of radioactivity from the Chernobyl accident

    International Nuclear Information System (INIS)

    Measurements of airborne radioactivity over Europe, Japan, and the United States indicated that the release from the Chernobyl reactor accident in the Soviet Union on April 26, 1986 contained a wide spectrum of fission up to heights of 7 km or more within a few days after the initial explosion. This high-altitude presence of radioactivity would in part be attributable to atmospheric dynamics factors other than the thermal energy released in the initial explosion. Indications were that two types of releases had taken place -- an initial powerful explosion followed by days of a less energetic reactor fire. The Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) utilized three-dimensional atmospheric dispersion models to determine the characteristics of the source term (release) and the evolution of the spatial distributions of the airborne radioactivity as it was transported over Europe and subsequently over the northern hemisphere. This paper describes the ARAC involvement and the results of the hemispheric model calculations which graphically depict the extensive dispersal of radioactivity. 1 fig

  6. Atmospheric dispersion of pollutants in an industrial area of Cuba

    International Nuclear Information System (INIS)

    Air pollution by different chemicals; take a great connotation in the world, given the adverse effects on ecosystems and particularly human health. The urban development, the modification of the land surface and the climate change, phenomena derived from a world population explosion, are altering the composition of the air. The atmosphere deposits pollutants in the water courses and in land, which harms not only the persons, but also to the animals and the plants of the ecosystem. To know as these pollutants are dispersed in the atmosphere it is very important in the establishment of better urban, regional and world predictions of the air quality. The present study aims to assess the local spread of sulphur dioxide, nitrogen oxides and particulate matter from an industrial zone. The study was done using the pollutant Gaussian Dispersion Models AERMOD. For the evaluation of contaminants were considered two modeling scenarios: urban and rural. The SO2 concentrations (μg/m3) were obtained for 1 h, 24 h and all period (1 year), exceeding the permissible limits (500, 50 y 20 μg/m3). It was also recorded for each period the number of times SO2 concentrations exceeded the reference values in each of the scenarios discussed (urban: 39, 61 y 39; rural: 99, 75 y 25). At the end of modeling in the urban setting, 39 recipients exceeded the reference value, occupying an area of 9.75 km2 and 25 receivers in the case of the rural setting, for an area of 6.25 km2. For NOx and particulate matter concentrations estimated values were always below the reference values. The obtained results in this case show the potentiality of AERMOD system for the evaluation of atmospheric dispersion of pollutants

  7. Atmospheric dispersion calculations in a low mountain area

    International Nuclear Information System (INIS)

    The applicability of the Gaussian model for assessing the short-range environmental exposure from an emission source in a topographically inhomogeneous terrain is tested. An atmospheric dispersion model of general applicability is used, which is based on results of hydrodynamic flow models. Approaches for turbulence and radiation parameterization are tested by means of a vertically one-dimensional flow model. In order to introduce the effects of the topography in the boundary-layer simulations, the three-dimensional mesoscale model (Ulrich) is applied. The two models are verified by way of episode simulation using wind profile measurements. The differences in the models' results are to show the topographic influence. The calculated flow fields serve as input to a randomwalk model applied for calculating ground-level concentration fields in the vicinity of an emission source. The Gaussian model underestimates the pollution under stable conditions. Convectivity conditions may change the effective source hight through vertical effects caused by orography which, depending on the direction of free flow, leads to an increase or decrease of pollutant concentration at ground level. Applying the more complex dispersion model, the concentration maxima under stable conditions are closer to the source by a factor five, and under unstable conditions about one and a half times more remote. (orig./HP)

  8. Critical review of studies on atmospheric dispersion in coastal regions

    Energy Technology Data Exchange (ETDEWEB)

    Shearer, D.L.; Kaleel, R.J.

    1982-09-01

    This study effort was required as a preliminary step prior to initiation of field measurements of atmospheric dispersion in coastal regions. The Nuclear Regulatory Commission (NRC) is in the process of planning an extensive field measurement program to generate data which will serve as improved data bases for licensing decisions, confirmation of regulations, standards, and guides, and for site characterizations. The study being reported here is an effort directed to obtaining as much information as is possible from existing studies that is relevant toward NRC's objectives. For this study, reports covering research and meteorological measurements conducted for industrial purposes, utility needs, military objectives, and academic studies were obtained and critically reviewed in light of NRC's current data needs. This report provides an interpretation of the extent of existing usable information, an indication of the potential for tailoring existing research toward current NRC information needs, and recommendations for several follow-on studies which could provide valuable additional information through reanalysis of the data. Recommendations are also offered regarding new measurement programs. Emphasis is placed on the identification and acquisition of data from atmospheric tracer studies conducted in coastal regions. A total of 225 references were identified which deal with the coastal atmosphere, including meteorological and tracer measurement programs, theoretical descriptions of the relevant processes, and dispersion models.

  9. Critical review of studies on atmospheric dispersion in coastal regions

    International Nuclear Information System (INIS)

    This study effort was required as a preliminary step prior to initiation of field measurements of atmospheric dispersion in coastal regions. The Nuclear Regulatory Commission (NRC) is in the process of planning an extensive field measurement program to generate data which will serve as improved data bases for licensing decisions, confirmation of regulations, standards, and guides, and for site characterizations. The study being reported here is an effort directed to obtaining as much information as is possible from existing studies that is relevant toward NRC's objectives. For this study, reports covering research and meteorological measurements conducted for industrial purposes, utility needs, military objectives, and academic studies were obtained and critically reviewed in light of NRC's current data needs. This report provides an interpretation of the extent of existing usable information, an indication of the potential for tailoring existing research toward current NRC information needs, and recommendations for several follow-on studies which could provide valuable additional information through reanalysis of the data. Recommendations are also offered regarding new measurement programs. Emphasis is placed on the identification and acquisition of data from atmospheric tracer studies conducted in coastal regions. A total of 225 references were identified which deal with the coastal atmosphere, including meteorological and tracer measurement programs, theoretical descriptions of the relevant processes, and dispersion models

  10. Evaluation of ensemble atmospheric simulations in oil dispersion models at Itaguai Port region; Avaliacao do uso de resultados numericos de previsao atmosferica por conjunto na modelagem da dispersao de oleo na regiao do Porto de Itaguai

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Renato Goncalves dos; Silva, Mariana P.R.; Silva, Ricardo Marcelo da; Torres Junior, Audalio R. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Modelagem de Processos Marinhos e Atmosfericos (LAMMA); Landau, Luiz [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Metodos Computacinais em Engenharia (LAMCE); Sa, Reginaldo Ventura de; Hochleitner, Fabio; Correa, Eduardo Barbosa [AQUAMET Meteorologia e Projeto de Sistemas, Rio de Janeiro, RJ (Brazil)

    2008-07-01

    This work discusses the use of numerical prediction using ensemble as boundary condition in pollutants dispersion models, applied in a hypothetical case of an oil spill occurrence in Itaguai Port. The Princeton Ocean Model (POM) has been used to simulate hydrodynamics and NICOIL Eulerian model to forecast oil spill dispersion, and ensemble wind forecast from Global Forecast System (GFS), aiming to assess the importance of this parameter variability in oil dispersion at sea. The wind scenarios using ensemble members has showed significant dispersion when compared to control simulation, demonstrating that the uncertainty in the atmospheric modeling can generate considerable variations in the placement of the final spot of oil. The region of interest was the Sepetiba Bay, located on the southern coast of the Rio de Janeiro state; because of port operations carried out around the Port of Itaguai where they can, eventually, oil leaks occur. (author)

  11. Use of data assimilation procedures in the meteorological pre-processors of decision support systems to improve the meteorological input of atmospheric dispersion models

    International Nuclear Information System (INIS)

    Full text: The Atmospheric Dispersion Models (ADMs) play a key role in decision support systems for nuclear emergency management, as they are used to determine the current, and predict the future spatial distribution of radionuclides after an accidental release of radioactivity to the atmosphere. Meteorological pre-processors (MPPs), usually act as interface between the ADMs and the incoming meteorological data. Therefore the quality of the results of the ADMs crucially depends on the input that they receive from the MPPs. The meteorological data are measurements from one or more stations in the vicinity of the nuclear power plant and/or prognostic data from Numerical Weather Prediction (NWP) models of National Weather Services. The measurements are representative of the past and current local conditions, while the NWP data cover a wider range in space and future time, where no measurements exist. In this respect, the simultaneous use of both by an MPP immediately poses the questions of consistency and of the appropriate methodology for reconciliation of the two kinds of meteorological data. The main objective of the work presented in this paper is the introduction of data assimilation (DA) techniques in the MPP of the RODOS (Real-time On-line Decision Support) system for nuclear emergency management in Europe, developed under the European Project 'RODOS-Migration', to reconcile the NWP data with the local observations coming from the meteorological stations. More specifically, in this paper: the methodological approach for simultaneous use of both meteorological measurements and NWP data in the MPP is presented; the method is validated by comparing results of calculations with experimental data; future ways of improvement of the meteorological input for the calculations of the atmospheric dispersion in the RODOS system are discussed. The methodological approach for solving the DA problem developed in this work is based on the method of optimal interpolation (OI

  12. Operational mesoscale atmospheric dispersion prediction using a parallel computing cluster

    Indian Academy of Sciences (India)

    C V Srinivas; R Venkatesan; N V Muralidharan; Someshwar Das; Hari Dass; P Eswara Kumar

    2006-06-01

    An operational atmospheric dispersion prediction system is implemented on a cluster supercomputer for Online Emergency Response at the Kalpakkam nuclear site.This numerical system constitutes a parallel version of a nested grid meso-scale meteorological model MM5 coupled to a random walk particle dispersion model FLEXPART.The system provides 48-hour forecast of the local weather and radioactive plume dispersion due to hypothetical airborne releases in a range of 100 km around the site.The parallel code was implemented on different cluster con figurations like distributed and shared memory systems.A 16-node dual Xeon distributed memory gigabit ethernet cluster has been found sufficient for operational applications.The runtime of a triple nested domain MM5 is about 4 h for a 24 h forecast.The system had been operated continuously for a few months and results were ported on the IMSc home page. Initial and periodic boundary condition data for MM5 are provided by NCMRWF,New Delhi. An alternative source is found to be NCEP,USA.These two sources provide the input data to the operational models at different spatial and temporal resolutions using different assimilation methods.A comparative study on the results of forecast is presented using these two data sources for present operational use.Improvement is noticed in rainfall forecasts that used NCEP data, probably because of its high spatial and temporal resolution.

  13. Estimation of NH3 emissions from a naturally ventilated livestock farm using local-scale atmospheric dispersion modelling

    Science.gov (United States)

    Hensen, A.; Loubet, B.; Mosquera, J.; van den Bulk, W. C. M.; Erisman, J. W.; Dämmgen, U.; Milford, C.; Löpmeier, F. J.; Cellier, P.; Mikuška, P.; Sutton, M. A.

    2009-12-01

    Agricultural livestock represents the main source of ammonia (NH3) in Europe. In recent years, reduction policies have been applied to reduce NH3 emissions. In order to estimate the impacts of these policies, robust estimates of the emissions from the main sources, i.e. livestock farms are needed. In this paper, the NH3 emissions were estimated from a naturally ventilated livestock farm in Braunschweig, Germany during a joint field experiment of the GRAMINAE European project. An inference method was used with a Gaussian-3D plume model and with the Huang 3-D model. NH3 concentrations downwind of the source were used together with micrometeorological data to estimate the source strength over time. Mobile NH3 concentration measurements provided information on the spatial distribution of source strength. The estimated emission strength ranged between 6.4±0.18 kg NH3 d-1 (Huang 3-D model) and 9.2±0.7 kg NH3 d-1 (Gaussian-3D model). These estimates were 94% and 63% of what was obtained using emission factors from the German national inventory (9.6 kg d-1 NH3). The effect of deposition was evaluated with the FIDES-2D model. This increased the emission estimate to 11.7 kg NH3 d-1, showing that deposition can explain the observed difference. The daily pattern of the source was correlated with net radiation and with the temperature inside the animal houses. The daily pattern resulted from a combination of a temperature effect on the source concentration together with an effect of variations in free and forced convection of the building ventilation rate. Further development of the plume technique is especially relevant for naturally ventilated farms, since the variable ventilation rate makes other emission measurements difficult.

  14. Estimation of NH3 emissions from a naturally ventilated livestock farm using local-scale atmospheric dispersion modelling

    Directory of Open Access Journals (Sweden)

    P. Cellier

    2009-12-01

    Full Text Available Agricultural livestock represents the main source of ammonia (NH3 in Europe. In recent years, reduction policies have been applied to reduce NH3 emissions. In order to estimate the impacts of these policies, robust estimates of the emissions from the main sources, i.e. livestock farms are needed. In this paper, the NH3 emissions were estimated from a naturally ventilated livestock farm in Braunschweig, Germany during a joint field experiment of the GRAMINAE European project. An inference method was used with a Gaussian-3D plume model and with the Huang 3-D model. NH3 concentrations downwind of the source were used together with micrometeorological data to estimate the source strength over time. Mobile NH3 concentration measurements provided information on the spatial distribution of source strength. The estimated emission strength ranged between 6.4±0.18 kg NH3 d−1 (Huang 3-D model and 9.2±0.7 kg NH3 d−1 (Gaussian-3D model. These estimates were 94% and 63% of what was obtained using emission factors from the German national inventory (9.6 kg d−1 NH3. The effect of deposition was evaluated with the FIDES-2D model. This increased the emission estimate to 11.7 kg NH3 d−1, showing that deposition can explain the observed difference. The daily pattern of the source was correlated with net radiation and with the temperature inside the animal houses. The daily pattern resulted from a combination of a temperature effect on the source concentration together with an effect of variations in free and forced convection of the building ventilation rate. Further development of the plume technique is especially relevant for naturally ventilated farms, since the variable ventilation rate makes other emission measurements difficult.

  15. Atmospheric dispersion in complex terrain: Angra-1 nuclear power plant

    International Nuclear Information System (INIS)

    The Angra 1 plant is located in a very complex terrain, what makes the environmental impact assessment very difficult, regarding to the atmospheric transport problem as well as to the diffusion problem. Three main characteristics are responsible for that situation: the location at the shoreline, the complex topography and the high roughness of the terrain. Those characteristics generate specific phenomena and utilization of parameters from other sites are not convenient. Considering financial and technical viabilities, we must look for the local parameters, disregarding the easy, although risky, attitude of applying parameters and models incovenient to the Angra site. Some of those aspects are more important, and among them we will discuss the Plume Rise, the Critical Height, the Drainage Flow and the Atmospheric Dispersion Coefficients. (Author)

  16. Numerical modeling of atmospheric flow and dispersion around a mountain%大气绕山体的运动及其输移特性的研究

    Institute of Scientific and Technical Information of China (English)

    李玲; 木村繁男

    2007-01-01

    对分层大气山体绕流的流动模式及扩散输移特性进行了数值模拟.采用隐式时间离散方法在贴体网格系统下求解雷诺平均的N-S方程,计算结果描述出大气流动的特征,证实了分层(以Froude数为特征参数,定义为F=U/NH,U为来流风速,N为Brunt-Vaisala频率,H为山体高度)变化对山体绕流流态的影响.数值结果表明:当Froude数大于4.0时,山体绕流的流动不再依赖于大气分层的变化.当Froude数介于4.0和1.0之间时,流场中出现了Lee波,并随着Froude数的进一步减小,流动分离发生及Lee波破碎现象.同时模型也预测了在各种流动模式下大气中夹杂着的污染物绕山体的传输特性,表明大气的分层现象对污染物的分布有着非常重要的影响.%A series of numerical experiments had been conducted to investigate the flow patterns and dispersion characteristics around a mountain under stably stratified flow. The two-dimensional model equations, based on the time-dependent Reynolds averaged Navier-Stokes equations, were solved numerically using an implicit time integration in body-fitted grid arrangement. The behavior of the flow is clarified to ascertain the effects of changes in the stratification, which is characterized by the Froude number F = U/NH (Where U is speed of the approaching wind, N is the Brunt-Vaisala frequency, and H is the mountain height). The numerical results suggest that the flow structure is independent of stratification when F>4.0. The model predicts lee wave generation as the Froude number is decreased from 4 to 1, then flow splitting, wave breaking phenomena happen as F is further decreased to less than 1.0. Further, the model-predicted concentration fields when the contaminant is coming with the approaching wind show that the stratification of atmospheric flow has significant effects on the dispersion pattern.

  17. Modelling tracer dispersion from landfills

    OpenAIRE

    Carpentieri, M.; Giambini, P; Corti, A.

    2008-01-01

    Several wind tunnel experiments of tracer dispersion from reduced-scale landfill models are presented in this paper. Different experimental set-ups, hot-wire anemometry, particle image velocimetry and tracer concentration measurements were used for the characterisation of flow and dispersion phenomena nearby the models. The main aim of these experiments is to build an extensive experimental data set useful for model validation purposes. To demonstrate the potentiality of the experimental data...

  18. High performance dispersion model PHYSIC

    International Nuclear Information System (INIS)

    The description and usage of the dispersion calculation model PHYSIC were summarized. The model was developed in the study of developing high performance SPEEDI with the purpose of introducing meteorological forecast function into the environmental emergency response system. PHYSIC consists of two parts, the three-dimensional meteorological model and the dispersion model. The former comprises primitive equations with Boussinesq approximation, which are solved by a finite difference method. The latter employs a particle dispersion method. PHYSIC can be used to evaluate the meteorological condition as well as the dispersion from a point source located in a complex terrain. The spatial and temporal scales of the model are 10 to 1000 km horizontally, 1 to 10 km vertically and 1 hour to 1 day, respectively. (author)

  19. Large-eddy simulation and Lagrangian stochastic modelling of solid particle and droplet dispersion and mixing. Application to atmospheric pollution; Dispersion et melange turbulents de particules solides et de gouttelettes par une simulation des grandes echelles et une modelisation stochastique lagrangienne. Application a la pollution de l'atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Vinkovic, I.

    2005-07-15

    In order to study atmospheric pollution and the dispersion of industrial stack emissions, a large eddy simulation with the dynamic Smagorinsky-Germano sub-grid-scale model is coupled with Lagrangian tracking of fluid particles containing scalar, solid particles and droplets. The movement of fluid particles at a sub-grid level is given by a three-dimensional Langevin model. The stochastic model is written in terms of sub-grid-scale statistics at a mesh level. By introducing a diffusion model, the coupling between the large-eddy simulation and the modified three-dimensional Langevin model is applied to passive scalar dispersion. The results are validated by comparison with the wind-tunnel experiments of Fackrell and Robins (1982). The equation of motion of a small rigid sphere in a turbulent flow is introduced. Solid particles and droplets are tracked in a Lagrangian way. The velocity of solid particles and droplets is considered to have a large scale component (directly computed by the large-eddy simulation) and a sub-grid scale part. Because of inertia and gravity effects, solid particles and droplets, deviate from the trajectories of the surrounding fluid particles. Therefore, a modified Lagrangian correlation timescale is introduced into the Langevin model previously developed for the sub-grid velocity of fluid particles. Two-way coupling and collisions are taken into account. The results of the large-eddy simulation with solid particles are compared with the wind-tunnel experiments of Nalpanis et al. (1993) and of Taniere et al. (1997) on sand particles in saltation and in modified saltation, respectively. A model for droplet coalescence and breakup is implemented which allows to predict droplet interactions under turbulent flow conditions in the frame of the Euler/Lagrange approach. Coalescence and breakup are considered as a stochastic process with simple scaling symmetry assumption for the droplet radius, initially proposed by Kolmogorov (1941). At high

  20. Modeling volcanic ash dispersal

    CERN Document Server

    CERN. Geneva

    2010-01-01

    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  1. Calculation of atmospheric dispersion factor for accident release from coastal nuclear power

    International Nuclear Information System (INIS)

    A model of calculating the probabilistic atmospheric dispersion factor for accident release from nuclear power plant (NPP), in which the effect of internal bound layer was taken into account and proposed. The final accident probabilistic dispersion factor used to evaluate dose, the dose for each pathway and the individual effective dose at the bound of a coastal NPP (0.5 km from the coastline) were estimated. The measured parameters from field atmosphere dispersion experiment on site of a NPP were applied. The result showed that not only the value of accident probabilistic dispersion factor but also the value of individual effective dose predicted were 5.9 times higher than those derived by a traditional model. Hence, the effect of internal bound layer on the accident dispersion factor and dose must be taken into account for coastal NPP when the frequency occurring internal bound layer is too high to be neglected

  2. Method for the instant approximation of atmospheric dispersion

    International Nuclear Information System (INIS)

    Mathematical evaluations of the radiologic impact of the transfer to man of radionuclides liberated into the environment are made with complex chains of models in which an early and essential link is always that of dispersion in air or water where the basic evaluations involve concentrations. In practice it often happens that the link of the concentration in the physical environment is overdeveloped in comparison to the other links and that the corresponding models are unnecessarily complicated. It appeared useful to develop a very simple basic primary model with few disagreements compatible with all of the existing models that it does not presume to replace. Naturally this model implies a certain number of stringent simplifying hypotheses, but at each point of space or time it only has a single parameter, the mixture thickness, real or equivalent, to characterize turbulent diffusion. A basic formula covering the short- and long-term situations, as well as transfers both within the atmosphere and to the ground (deposits) is supplied in the form of a single summary table. 4 references, 1 figure, 1 table

  3. Dispersion of Fukushima radionuclides in the global atmosphere and the ocean

    International Nuclear Information System (INIS)

    Large quantities of radionuclides were released in March–April 2011 during the accident of the Fukushima Dai-ichi Nuclear Power Plant to the atmosphere and the ocean. Atmospheric and marine modeling has been carried out to predict the dispersion of radionuclides worldwide, to compare the predicted and measured radionuclide concentrations, and to assess the impact of the accident on the environment. Atmospheric Lagrangian dispersion modeling was used to simulate the dispersion of 137Cs over America and Europe. Global ocean circulation model was applied to predict the dispersion of 137Cs in the Pacific Ocean. The measured and simulated 137Cs concentrations in atmospheric aerosols and in seawater are compared with global fallout and the Chernobyl accident, which represent the main sources of the pre-Fukushima radionuclide background in the environment. The radionuclide concentrations in the atmosphere have been negligible when compared with the Chernobyl levels. The maximum 137Cs concentration in surface waters of the open Pacific Ocean will be around 20 Bq/m3. The plume will reach the US coast 4–5 y after the accident, however, the levels will be below 3 Bq/m3. All the North Pacific Ocean will be labeled with Fukushima 137Cs 10 y after the accident with concentration bellow 1 Bq/m3. - Highlights: • Modeling of Fukushima radionuclides in the atmosphere. • Modeling of Fukushima radionuclides in the Pacific. • Comparison of the Fukushima radionuclide impact with global fallout. • Comparison of Fukushima and Chernobyl radionuclide releases

  4. Nonisothermal Pluto atmosphere models

    International Nuclear Information System (INIS)

    The present thermal profile calculation for a Pluto atmosphere model characterized by a high number fraction of CH4 molecules encompasses atmospheric heating by solar UV flux absorption and conductive transport cooling to the surface of Pluto. The stellar occultation curve predicted for an atmosphere of several-microbar surface pressures (which entail the existence of a substantial temperature gradient close to the surface) agrees with observations and implies that the normal and tangential optical depth of the atmosphere is almost negligible. The minimum period for atmospheric methane depletion is calculated to be 30 years. 29 refs

  5. Dispersion modeling using personal computers

    Science.gov (United States)

    Schulze, Richard H.

    The widespread availability of personal computers and PC versions of models for these computers is changing the way dispersion modeling is performed. Research scientists, environmental engineers and meteorologists, whether associated with institutes, industry or regulatory agencies, can use screening models to determine the effect of proposed changes, and when more complicated studies are warranted. As model use becomes more egalitarian, better use of intellectual talent among modelers will occur. Scientists can focus on more difficult problems while industry and agency personnel can focus on more routine issues. Moreover, the presently available models enable nearly anyone with some scientific training to perform modeling and make reasonable estimates of air quality changes.

  6. MET-RODOS: a comprehensive atmospheric dispersion module

    International Nuclear Information System (INIS)

    A comprehensive meteorological dispersion module called MET-RODOS is being developed to serve the real-time RODOS decision support system with an integrated prediction capability for airborne radioactive spread, deposition and gamma radiation exposure on all scales. Deposition, ground-level air concentrations, and ground level gamma dose rates from up to 15 simultaneous released nuclides are calculated using a nested system of local and long-range atmospheric dispersion models, driven by real-time available on-line meteorological information. The MET-RODOS module uses concurrently the available source term and weather information in the RODOS data base system, and returns, up to +36 hour forecasts of nuclei-specific air and deposited concentrations including gamma dose rate estimations for display and subsequent processing within the RODOS framework. Weather and meteorology is available to the system via on-line connections to on-site local meteorological observations (met-towers and sodars) and via network (either public-domain Internet or user-owned point-to-point ISDN) connections to remote national or international meteorological forecasting services. In its final form, scheduled for operational use in 1999, the MET-RODOS meteorological module is intended to service the RODOS system with actual and forecast (+36 hour) nuclei-specific air concentrations, deposition values, and gamma radiation estimates on the local, national, and European scale. Provisions are furthermore being made for accommodating on-line available radiological monitoring data in the meteorological model chains in order for the module to assist with source term determination based on real-time data-assimilation and back-fitting procedures. (orig.)

  7. Investigation and calculation on the atmospheric dispersion of radionuclides release from Ninh Thuan nuclear power plant

    International Nuclear Information System (INIS)

    The atmospheric dispersion model can be applied to forecast and evaluate the distribution of pollutant concentrations in ambient air by one or more fixed sources causing in the surrounding area. Besides, to obtain the transport parameters in air environment, we have collected aerosols and fallout samples in Phan Rang meteorological stations in the period from 7/2010 to 5/2011. From the data on the concentration and density of deposition of radioactive isotopes obtained in Phan Rang, wet/dry deposition velocities and washout ratio were calculated to provide input data for dispersion models. The regional meteorological, topography data and technological parameters of the plant emissions along with the transport parameters of radioactive isotopes is the key input data for dispersion models. Atmospheric dispersion modeling with various atmospheric stability classes, viz., Pasquill categories A-F, and ORION-WIN and CALPUFF computer codes have been investigated and applied to take part in resolving the environmental pollution problem. The artificial radionuclide concentration data of the air parcel at the ground were calculated surrounding Ninh Thuan nuclear power plant (1000 MW power, 150 m stack height) at the prevailing wind directions in both dry and rainy seasons. The obtained results show that the distance in which the radionuclide concentrations of the air parcel at the ground reached maximum were estimated by using the atmospheric dispersion modeling to be about 1.5-1.8 km from the plant stack. (author)

  8. Atmospheric dispersion and the implications for phase calibration

    CERN Document Server

    Curtis, Emily I; Richer, John S; Pardo, Juan R

    2009-01-01

    The success of any ALMA phase-calibration strategy, which incorporates phase transfer, depends on a good understanding of how the atmospheric path delay changes with frequency (e.g. Holdaway & Pardo 2001). We explore how the wet dispersive path delay varies for realistic atmospheric conditions at the ALMA site using the ATM transmission code. We find the wet dispersive path delay becomes a significant fraction (>5 per cent) of the non-dispersive delay for the high-frequency ALMA bands (>160 GHz, Bands 5 to 10). Additionally, the variation in dispersive path delay across ALMA's 4-GHz contiguous bandwidth is not significant except in Bands 9 and 10. The ratio of dispersive path delay to total column of water vapour does not vary significantly for typical amounts of water vapour, water vapour scale heights and ground pressures above Chajnantor. However, the temperature profile and particularly the ground-level temperature are more important. Given the likely constraints from ALMA's ancillary calibration devi...

  9. Numerical modelling and parametric study of the atmospheric dispersion after radionuclide releases: the Chernobyl accident and the Algeciras incident. Comparison with observation data

    International Nuclear Information System (INIS)

    Full text: The attempts of modelling the release following upon the Chernobyl accident and the Algeciras incident are reported. Computing power and observation database are used for sensitivity and parametric studies. The meteorological mesoscale model MM5 is nudged with the ERA-40 reanalysis to simulate the meteorological conditions used by the dispersion model, POLAIR3D. In case of the Chernobyl accident the points of interest are many: the representativity of the meteorological simulations is evaluated using observations with a special focus on precipitation events. The radionuclide dispersion, the dry deposition and scavenging simulated by POLAIR3D are compared with European measurements of activities and depositions. Results of the sensitivity studies are done to evaluate the impact of the deposition parameterizations and source-term characteristics (height of release, quantities). The time dynamic of the contaminated cloud is also investigated with regard to the arrival time on different countries. Similarly, for the Algeciras release, sensitivity to the meteorological fields, source term and depletion processes are analyzed. For the available activity concentrations in the air, data-model comparisons are performed. (author)

  10. Coupling constant in dispersive model

    Indian Academy of Sciences (India)

    R Saleh-Moghaddam; M E Zomorrodian

    2013-11-01

    The average of the moments for event shapes in + - → hadrons within the context of next-to-leading order (NLO) perturbative QCD prediction in dispersive model is studied. Moments used in this article are $\\langle 1 - T \\rangle, \\langle ρ \\rangle, \\langle B_{T} \\rangle$ and $\\langle B_{W} \\rangle$. We extract , the coupling constant in perturbative theory and α0 in the non-perturbative theory using the dispersive model. By fitting the experimental data, the values of $(M_{Z^{°}})$ = 0.1171 ± 0.00229 and 0 ($_{I} = 2{\\text{GeV}}$) = 0.5068 ± 0.0440 are found. Our results are consistent with the above model. Our results are also consistent with those obtained from other experiments at different energies. All these features are explained in this paper.

  11. An atmospheric dispersion model for linear sources in calm wind, stable conditions; Un modello di dispersione atmosferica per sorgenti lineari in condizioni di vento debole

    Energy Technology Data Exchange (ETDEWEB)

    Cirillo, M. C. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Buratti, D. [Rome Univ. La Sapienza, Rome (Italy). Facolta' di Scienze Statistiche; Metallo, M. C.; Poli, A.A. [ESA s.a.s., Bracciano, RM (Italy)

    1999-07-01

    In this report a dispersion model is proposed that provides an estimate of concentration of gaseous pollutants emitted by an highway, or in general by a line source, in presence of low wind speed. This aim was pursued because available models have not a satisfactory behaviour in such conditions, which is critical for dispersion of gaseous pollutants. This lack is due to difficulty of simulating dispersion turbulent component which is determined by fluctuation of wind speed and wind direction, and in presence of calm conditions it assumes values comparable with transport component. The proposed model overcomes this difficulty, as it is shown by sensitivity analysis and comparison with experimental data. The capability of simulating dispersion eve in critical conditions, like the presence of low level inversion, and the absence of source geometrical approximations make the model a tool that, properly used, may contribute to the efficient planning and management of environmental resources. [Italian] In questo rapporto viene proposto un modello per la stima delle concentrazioni di inquinanti aeriformi emessi da un'arteria stradale, o in generale da una sorgente lineare, in presenza di vento debole. Questo scopo e' stato perseguito in quanto in questa condizione, nonostante la dispersione degli inquinanti risulti fortemente problematica, i modelli disponibili in letteratura non hanno un comportamento soddisfacente. Questa mancanca e' attribuibile alla difficolta' di simulare la componente turbolenta della dispersione, dovuta alla fluttuazione della direzione e della velocita' del vento che, in presenza di vento debole, assume valori confrontabili alla componente di trasporto. Il modello qui di seguito proposto supera questa difficolta', come dimostrano l'analisi di sensibilita' e il confronto con un caso reale; la capacita' di simulare la dispersione anche in condizioni fisicamente critiche quali la presenza di inversione a

  12. The impact of the site meteorological conditions, model and parameters of atmospheric dispersion on the assessment results of public radiation exposure under normal operation of nuclear facilities

    International Nuclear Information System (INIS)

    The real meteorological condition of the nuclear facilities located in different regions in China was used to do the comparative evaluation of the public radiation exposure from airborne effluent of a hypothetical 1000 MWe pressure water reactor (PWR) under the routine operation. The public radiation exposure is far less than the State Radiation Exposure Limit, because the airborne emission from the 1000 MWe PWR under the routine operation is very low. The site-meteorological condition, the dispersion model and its parameters have little influence on the public radiation exposure. Therefore it can simplify the assessment of the impact on environment of nuclear power station. (4 tabs., 4 figs.)

  13. The brasimone study (brastud) an investigation of atmospheric dispersion over complex terrain

    International Nuclear Information System (INIS)

    An investigation of atmospheric dispersion over complex terrain was carried out in September 1984 and in June 1985 at the Brasimone Energy Research Centre (B.E.R.C.). This place, where an experimental nuclear reactor is under construction, is located in the Tuscan-Emilian Appennine range approximately 50 km south of Bologna. The measuring campaigns, based on survey of wind and temperature parameters, tracer (SF6) experiments and tracking of tetroons by radar, were performed with the purpose of assessing the atmospheric dispersion of pollutants under nocturnal drainage flow conditions. The three-dimensional MATHEW/ADPIC model was evaluated with the Brasimone data set and the results obtained are satisfactory

  14. Analysis on the structure of the TMT's Atmospheric Dispersion Corrector

    Science.gov (United States)

    Zhang, Jianhuan; Liu, Yan; Tao, Jin

    2015-10-01

    The concepts of atmospheric refraction and atmospheric dispersion are introduced and the method of how to eliminate atmospheric dispersion. This article introduces the structure of Atmospheric Dispersion Correction , the installation position of ADC in TMT telescope and the introduction to the principle of ADC in detail. Using the finite element analysis software Ansys Workbench to analyze the rationality of the ADC structure. Static analysis The ADC structure is loaded with two tape lens, which is more 400kg in weight, as well as itself weight, will deform in x, y, z directions. Dynamic analysis The dynamic performances of ADC structure are very important for the construction of the instrument, for the environmental vibration need to be tested. That is the effect of ADC dynamic deformation on optical accuracy is crucial for imaging quality. Here three order modes of dynamic performance are presented for the references of ADC design. They are 1st order mode , 2nd order mode and 3rd order mode. Thermal deformation according to the ADC working environment temperature change, the instrument temperature would be from -5 to 9 degree. So the thermal deformation of ADC is performed in this temperature fluctuation. ADC structure FEA conclusions: The ADC tapered lens are assumed as a rigid body and the mechanical analysis results are: Static analysis, Kinetics analysis and Thermodynamic analysis. Based on the FEA results, we get the image motion information in the telescope plane. Then, we draw a conclusion that: image motions induced by current structure design are very small and meet the requirements of ADC.

  15. Development of an atmospheric dispersion and dose calculation code for real-time response by using small-scale computer

    International Nuclear Information System (INIS)

    This report describes a development of a wind field calculation code and an atmospheric dispersion and dose calculation code which can be used for real-time prediction in an emergency. Models used in the computer codes are a mass-consistent model for wind field and a particle diffusion model for atmospheric dispersion. In order to attain quick response even when the codes are used in a small-scale computer, high-speed iteration method (MILUCR) and kernel density method are applied to the wind field model and the atmospheric and dose calculation model, respectively. In this report, numerical models, computational codes, related files and calculation examples are shown. (author)

  16. Lagrangian modeling of atmospheric dispersion of radionuclides and geographical information systems as tools to support emergency planning in area of influence of nuclear complex of Angra dos Reis, RJ, Brazil

    International Nuclear Information System (INIS)

    Industrial accidents generally endanger structures and the set of environmental influence area where the enterprises are located, especially when affected by atmospheric dispersion of their pollutants, whose concern with the evacuation of the population is the main goal in emergency situations. Considering the nuclear complex Angra dos Reis - RJ, based on computer modeling analysis of the mechanisms of pollutant dispersion in conjunction with geographic information systems were developed. Thus, information about the dispersion of radionuclides - from simulations performed on the HYSPLIT; meteorological data (direction, intensity and calm on the wind regime and analysis of the wind field in the region using WRF), occurrence of landslides and data on the environmental study area were integrated into a GIS database using ArcGIS platform. Aiming at the identification and definition of escape routes in case of evacuation from accidental events in CNAAA, the results point solutions for long-term planning, based on weather and landslides, and short-term, supported by simulations of the dispersion radionuclides, in order to support actions that assist local emergency planning. (author)

  17. Solar Atmosphere Models

    Science.gov (United States)

    Rutten, R. J.

    2002-12-01

    This contribution honoring Kees de Jager's 80th birthday is a review of "one-dimensional" solar atmosphere modeling that followed on the initial "Utrecht Reference Photosphere" of Heintze, Hubenet & de Jager (1964). My starting point is the Bilderberg conference, convened by de Jager in 1967 at the time when NLTE radiative transfer theory became mature. The resulting Bilderberg model was quickly superseded by the HSRA and later by the VAL-FAL sequence of increasingly sophisticated NLTE continuum-fitting models from Harvard. They became the "standard models" of solar atmosphere physics, but Holweger's relatively simple LTE line-fitting model still persists as a favorite of solar abundance determiners. After a brief model inventory I discuss subsequent work on the major modeling issues (coherency, NLTE, dynamics) listed as to-do items by de Jager in 1968. The present conclusion is that one-dimensional modeling recovers Schwarzschild's (1906) finding that the lower solar atmosphere is grosso modo in radiative equilibrium. This is a boon for applications regarding the solar atmosphere as one-dimensional stellar example - but the real sun, including all the intricate phenomena that now constitute the mainstay of solar physics, is vastly more interesting.

  18. Review of specific effects in atmospheric dispersion calculations

    International Nuclear Information System (INIS)

    This report consists of a series of 7 individual review chapters -written between 1980 and 1983- together with a summary document linking and overviewing the work. The topics covered are as follows: ''atmospheric dispersion in urban environments''; ''topographical effects in nuclear safety studies''; coastal effects and transport over water''; ''time-varying meteorology in consequence assessment''; ''building effects in nuclear safety studies''; effect of variations in mixing height on atmospheric dispersion''; ''the effect of turning of the wind with height on lateral dispersion''. Although the reviews are, on the whole, general in approach, emphasis has been given where appropriate to the impact of various phenomena on the assessment of reactor accident consequences. In general the work focuses on the 0-100 km range of distance downwind of the source. The reviews fulfil several functions: they serve as introductions to the subject areas; they outline theoretical and experimental developments; they act as reference documents providing a copious source of references for more detailed investigation of particular points; they raise unresolved technical issues and attempt to indicate principal uncertainties; they point to areas requiring further development

  19. Dispersion of aerosol particles in the atmosphere: Fukushima

    Science.gov (United States)

    Haszpra, Tímea; Lagzi, István; Tél, Tamás

    2013-04-01

    Investigation of dispersion and deposition of aerosol particles in the atmosphere is an essential issue, because they have an effect on the biosphere and atmosphere. Moreover, aerosol particles have different transport properties and chemical and physical transformations in the atmosphere compared to gas phase air pollutants. The motion of a particle is described by a set of ordinary differential equations. The large-scale dynamics in the horizontal direction can be described by the equations of passive scalar advection, but in the vertical direction a well-defined terminal velocity should be taken into account as a term added to the vertical wind component. In the planetary boundary layer turbulent diffusion has an important role in the particle dispersion, which is taken into account by adding stochastic terms to the deterministic equations above. Wet deposition is also an essential process in the lower levels of the atmosphere, however, its precise parameterization is a challenge. For the simulations the wind field and other necessary data were taken from the ECMWF ERA-Interim database. In the case of the Fukushima Daiichi nuclear disaster (March-April 2011) radioactive aerosol particles were also released in the planetary boundary layer. Simulations (included the continuous and varying emission from the nuclear power plant) will be presented for the period of 14-23 March. Results show that wet deposition also has to be taken into consideration in the lower levels of the atmosphere. Furthermore, dynamical system characteristics are evaluated for the aerosol particle dynamics. The escape rate of particles was estimated both with and without turbulent diffusion, and in both cases when there was no wet deposition and also when wet deposition was taken into consideration.

  20. Lateral Dispersion of Pollutants in a Very Stable Atmosphere - The Effect of Meandering

    DEFF Research Database (Denmark)

    Kristensen, Leif; Jensen, Niels Otto; Lundtang Petersen, Erik

    1981-01-01

    A model based on single particle diffusion is introduced to account for the effect of “meandering” on lateral plume dispersion in a very stable atmosphere. It is assumed that small scale atmospheric turbulence is absent, so that only large horizontal eddies are effective. A formula for the lateral....... Meteorological data from Risø and the small island Sprogø have been analysed in order to identify all situations in which the atmosphere is so stable that small scale turbulence cannot exist. The purpose is to see in how many of these situations meandering is also absent. The results show that, as a rule...

  1. Dispersion modelling studies: the 1984 experiment in Angra dos Reis

    International Nuclear Information System (INIS)

    The results of a numerical modelling of an atmospheric dispersion in Angra dos Reis (RJ, Brazil) are considered. A comparison between model results and monitored field concentrations is discussed from the point of view of its statistical as well as physical significance. Particular attention has been paid to the effects of the lack of homogeneity in the spatial scale (horizontal and vertical) and in the time scale (stationarity in the local meteorology), as they can be critical in coastal areas. Some suggestions are made about a real time modelling of the atmospheric dispersion on the considered site. (author)

  2. Urban dispersion : challenges for fast response modeling

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M. J. (Michael J.)

    2004-01-01

    There is renewed interest in urban dispersion modeling due to the need for tools that can be used for responding to, planning for, and assessing the consequences of an airborne release of toxic materials. Although not an everyday phenomenon, releases of hazardous gases and aerosols have occurred in populated urban environments and are potentially threatening to human life. These releases may stem from on-site accidents as in the case of industrial chemical releases, may result during transport of hazardous chemicals as in tanker truck or railroad spills, or may be premeditated as in a chemical, biological, or radiological (CBR) agent terrorist attack. Transport and dispersion in urban environments is extremely complicated. Buildings alter the flow fields and deflect the wind, causing updrafts and downdrafts, channeling between buildings, areas of calm winds adjacent to strong winds, and horizontally and vertically rotating-eddies between buildings, at street corners, and other places within the urban canopy (see review by Hosker, 1984). Trees, moving vehicles, and exhaust vents among other things further complicate matters. The distance over which chemical, biological, or radiological releases can be harmful varies from tens of meters to many kilometers depending on the amount released, the toxicity of the agent, and the atmospheric conditions. As we will show later, accounting for the impacts of buildings on the transport and dispersion is crucial in estimating the travel direction, the areal extent, and the toxicity levels of the contaminant plume, and ultimately for calculating exposures to the population.

  3. An evaluation of dry deposition from the long range atmospheric dispersion

    International Nuclear Information System (INIS)

    The dry deposition of pollutants released into the atmosphere must be evaluated to estimate the radiological dose of terrestrial plants and foodstuffs in the ecosystem. Especially, the atmospheric dispersion and dry deposition models have been widely developed to predict and minimize the radiological damage for the surrounding environment after the TMI-2 and the Chernobyl accidents. A Lagrangian particle model for the evaluation the long-range dispersion has been firstly developed in Korea since 2001. The particle tracking method was used for the estimation of the concentration distribution of the radioactive materials released into the atmosphere. The model is designed to estimate air concentration and ground deposition at distances up to some thousands of kilometers from the source point in the horizontal direction. The turbulent motion is considered to separate the treatment of particles within the mixing layer and above the mixing layer. Also, the dispersion model is designed to receive the results of the MM5 model being operated by KMA (Korea Meteorological Administration). The test run of the long-range dispersion model has been performed in the area which covered extends from 102.47deg E to 173.34deg E and from 12.27deg N to 53.72deg N in Northeast Asia. The release point of Cs-137 assumed in the east part of the China. The long range dispersion model has been firstly developed to estimate the radiological consequences against a nuclear accident. The model will be supplemented by the comparative study using the data of the ETEX experiments. (author)

  4. Modified ensemble Kalman filter for nuclear accident atmospheric dispersion: Prediction improved and source estimated

    International Nuclear Information System (INIS)

    Highlights: • A modified ensemble Kalmen filter data assimilation method is proposed. • The method can consider four main uncertain parameters in the puff model. • The prediction of radioactive material atmospheric dispersion is improved. • The source release rate and plume rise height are successfully reconstructed. • It can shorten the time lag in the response of ensemble Kalmen filter. - Abstract: Atmospheric dispersion models play an important role in nuclear power plant accident management. A reliable estimation of radioactive material distribution in short range (about 50 km) is in urgent need for population sheltering and evacuation planning. However, the meteorological data and the source term which greatly influence the accuracy of the atmospheric dispersion models are usually poorly known at the early phase of the emergency. In this study, a modified ensemble Kalman filter data assimilation method in conjunction with a Lagrangian puff-model is proposed to simultaneously improve the model prediction and reconstruct the source terms for short range atmospheric dispersion using the off-site environmental monitoring data. Four main uncertainty parameters are considered: source release rate, plume rise height, wind speed and wind direction. Twin experiments show that the method effectively improves the predicted concentration distribution, and the temporal profiles of source release rate and plume rise height are also successfully reconstructed. Moreover, the time lag in the response of ensemble Kalman filter is shortened. The method proposed here can be a useful tool not only in the nuclear power plant accident emergency management but also in other similar situation where hazardous material is released into the atmosphere

  5. A user's guide to the atmospheric dispersion module NECTAR-ATMOS

    International Nuclear Information System (INIS)

    The NECTAR environmental computer code has been developed to meet the increasing demand for comprehensive calculations of the radiological consequences due to atmospheric releases of radioactivity. The code contains five calculational modules and this report presents a user's guide to the atmospheric dispersion and individual dose evaluation module NECTAR-ATMOS. The mathematical models employed in NECTAR-ATMOS are briefly described and a complete specification of the input data required for the module is given. The program includes facilities for reading in the source terms, for specifying the atmospheric dispersion parameters, for identifying the dose calculations required and for controlling output from the program to lineprinters and to output utility files. Three sample cases are included in an appendix to demonstrate some of the different ways in which the program may be used and also to provide examples for the prospective user. (author)

  6. Global risk from the atmospheric dispersion of radionuclides by nuclear power plant accidents in the coming decades

    OpenAIRE

    Christoudias, T.; Proestos, Y.; Lelieveld, J.

    2014-01-01

    We estimate the global risk from the release and atmospheric dispersion of radionuclides from nuclear power plant accidents using the EMAC atmospheric chemistry–general circulation model. We included all nuclear reactors that are currently operational, under construction and planned or proposed. We implemented constant continuous emissions from each location in the model and simulated atmospheric transport and removal via dry and wet deposition processes over 20 years (2010–...

  7. Global risk from the atmospheric dispersion of radionuclides by nuclear power plant accidents

    Science.gov (United States)

    Christoudias, Theodoros; Proestos, Yiannis; Lelieveld, Jos

    2015-04-01

    We estimate the global risk from the release and atmospheric dispersion of radionuclides from nuclear power plant accidents using the EMAC atmospheric chemistry-general circulation model. We included all nuclear reactors that are currently operational, under construction and planned or proposed. We simulated atmospheric transport and decay, focusing on 137Cs and 131I as proxies for particulate and gaseous radionuclides, respectively. We implemented constant continuous emissions from each location in the model and simulated atmospheric transport and removal via dry and wet deposition processes. We present risk maps for potential surface layer concentrations, deposition and doses to humans from the inhalation exposure of 131I. The estimated risks exhibit seasonal variability, with the highest surface level concentrations of gaseous radionuclides in the Northern Hemisphere during winter.

  8. Atmospheric pollution. From processes to modelling

    International Nuclear Information System (INIS)

    Air quality, greenhouse effect, ozone hole, chemical or nuclear accidents.. All these phenomena are tightly linked to the chemical composition of atmosphere and to the atmospheric dispersion of pollutants. This book aims at supplying the main elements of understanding of 'atmospheric pollutions': stakes, physical processes involved, role of scientific expertise in decision making. Content: 1 - classifications and scales: chemical composition of the atmosphere, vertical structure, time scales (transport, residence); 2 - matter/light interaction: notions of radiative transfer, application to the Earth's atmosphere; 3 - some elements about the atmospheric boundary layer: notion of scales in meteorology, atmospheric boundary layer (ABL), thermal stratification and stability, description of ABL turbulence, elements of atmospheric dynamics, some elements about the urban climate; 4 - notions of atmospheric chemistry: characteristics, ozone stratospheric chemistry, ozone tropospheric chemistry, brief introduction to indoor air quality; 5 - aerosols, clouds and rains: aerosols and particulates, aerosols and clouds, acid rains and leaching; 6 - towards numerical simulation: equation of reactive dispersion, numerical methods for chemistry-transport models, numerical resolution of the general equation of aerosols dynamics (GDE), modern simulation chains, perspectives. (J.S.)

  9. Solutions of atmospheric dispersion equation and parameters in the boundary layer

    International Nuclear Information System (INIS)

    There is an increasing interest in studies of atmospheric aerosols in the context of their impact and atmospheric chemistry associated. In this work attention was paid to mathematical relationship to evaluate air dispersion concentrations under different conditions.The material in the present thesis is organized in three chapters in the following way:In chapter (1), we describe as. In section 1-1, General introduction. In section 1-2. Study atmosphere boundary layer, in section 1-3.Study atmospheric diffusion, In section 1-4, defined the concentration, In section 1-5, Defined the dispersion and diffusion .In section 6.Characterization of Turbulent Diffusion.In chapter (2), we derive a simple solution of the steady state, dimensional diffusion equation that describes advection in the direction of the wind and diffusion in the vertical direction using separation method. The separation method has been found to give solution, which agrees well with observed concentration of sulfur dioxide. In section 1, we study the mathematically analogous problem of dispersal pollution over area sources. In section 2-2, we give a description of the analytical method, In section 2-3, we give a description of the numerical method while in section 2-4 and 2-5, we give an application of the method to the calculation of dispersal of sulfur dioxide in a 2-h, steady state period in the atmosphere of Nashville. Tennessee.In chapter (3), we estimated the concentration of PM10 (where it is the portion of particulate matter in the air having an aerodynamic equivalent diameter (AED) less than or equal to 10 μm) and compare horizontal flux calculations presented by (Veranth et al. (2003)) with emissions measured from a dispersion model applied to the same data. The next section is used to study the system of computing Horizontal fluxes. In section 3-2, using the mathematical techniques to derived the parameters such as the expressions and the mean plume velocity (where the mathematical

  10. Dispersion model maps spread of Fukushima radiation

    Science.gov (United States)

    Schultz, Colin

    2013-01-01

    When water flooded the Japanese Fukushima Daiichi nuclear power plant on 11 March 2011, killing power to the plant and destroying its backup generators, the earthquake-triggered disaster resulted in a major nuclear accident, with the plant pouring radioactive material into the air and the water. Research into the effects of the radiation on humans and the environment has been ongoing, but to ensure the accuracy of these aftermath investigations requires understanding the precise concentrations, distribution patterns, and timing of the radionuclide emissions. To provide such an assessment for the marine environment, Estournel et al. used an ocean and atmosphere dispersion model to simulate the movements of radioactive cesium-137 throughout the Japanese coastal waters for 3.5 months following the earthquake.

  11. Modeling electrical dispersion phenomena in Earth materials

    OpenAIRE

    D. Patella

    2008-01-01

    It is illustrated that IP phenomena in rocks can be described using conductivity dispersion models deduced as solutions to a 2nd-order linear differential equation describing the motion of a charged particle immersed in an external electrical field. Five dispersion laws are discussed, namely: the non-resonant positive IP model, which leads to the classical Debye-type dispersion law and by extension to the Cole-Cole model, largely used in current practice; the non-resonant negative...

  12. A hybrid plume model for local-scale dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Nikmo, J.; Tuovinen, J.P.; Kukkonen, J.; Valkama, I.

    1997-12-31

    The report describes the contribution of the Finnish Meteorological Institute to the project `Dispersion from Strongly Buoyant Sources`, under the `Environment` programme of the European Union. The project addresses the atmospheric dispersion of gases and particles emitted from typical fires in warehouses and chemical stores. In the study only the `passive plume` regime, in which the influence of plume buoyancy is no longer important, is addressed. The mathematical model developed and its numerical testing is discussed. The model is based on atmospheric boundary-layer scaling theory. In the vicinity of the source, Gaussian equations are used in both the horizontal and vertical directions. After a specified transition distance, gradient transfer theory is applied in the vertical direction, while the horizontal dispersion is still assumed to be Gaussian. The dispersion parameters and eddy diffusivity are modelled in a form which facilitates the use of a meteorological pre-processor. Also a new model for the vertical eddy diffusivity (K{sub z}), which is a continuous function of height in the various atmospheric scaling regions is presented. The model includes a treatment of the dry deposition of gases and particulate matter, but wet deposition has been neglected. A numerical solver for the atmospheric diffusion equation (ADE) has been developed. The accuracy of the numerical model was analysed by comparing the model predictions with two analytical solutions of ADE. The numerical deviations of the model predictions from these analytic solutions were less than two per cent for the computational regime. The report gives numerical results for the vertical profiles of the eddy diffusivity and the dispersion parameters, and shows spatial concentration distributions in various atmospheric conditions 39 refs.

  13. Investigation of the influence of modified parameters in the atmospheric dispersion model on the results of the German Risk Study (DRS)

    International Nuclear Information System (INIS)

    A substantial criterion in preparing Phase A of the German Risk Study was its comparability with the U. S. Reactor Safety Study. Therefore, a number of basic assumptions and methodological principles were to be identical with those adopted in the American study. For Phase B of the German Risk Study improvements of the method will be used to a greater extent and recent results of research work taken into account. A first step in this direction will consists in investigating the influence exerted by modified parameters in the dispersion submodel. The other parameters, besides dry and wet deposition, are the height of the mixing layer, the dispersion parameters and the wind direction. Furthermore, the degree will be studied at which the selection of weather sequences have an influence on the collective risks. All results indicated will be related to the results obtained in Phase A. (orig.)

  14. Lateral Dispersion of Pollutants in a Very Stable Atmosphere - The Effect of Meandering

    DEFF Research Database (Denmark)

    Kristensen, Leif; Jensen, Niels Otto; Lundtang Petersen, Erik

    1981-01-01

    A model based on single particle diffusion is introduced to account for the effect of “meandering” on lateral plume dispersion in a very stable atmosphere. It is assumed that small scale atmospheric turbulence is absent, so that only large horizontal eddies are effective. A formula for the lateral...... standard deviation σy as function of observation time, distance from source, mean wind speed, lateral turbulence intensity, and scale of the atmospheric motion is derived. Climatological time series of temperature lapse rates, wind speeds, and wind directions can be used as input to calculate σy....... Meteorological data from Risø and the small island Sprogø have been analysed in order to identify all situations in which the atmosphere is so stable that small scale turbulence cannot exist. The purpose is to see in how many of these situations meandering is also absent. The results show that, as a rule...

  15. A high precision technique to correct for residual atmospheric dispersion in high-contrast imaging systems

    CERN Document Server

    Pathak, P; Jovanovic, N; Lozi, J; Martinache, F; Minowa, Y; Kudo, T; Takami, H; Hayano, Y; Narita, N

    2016-01-01

    Direct detection and spectroscopy of exoplanets requires high contrast imaging. For habitable exoplanets in particular, located at small angular separation from the host star, it is crucial to employ small inner working angle (IWA) coronagraphs that efficiently suppress starlight. These coronagraphs, in turn, require careful control of the wavefront which directly impacts their performance. For ground-based telescopes, atmospheric refraction is also an important factor, since it results in a smearing of the PSF, that can no longer be efficiently suppressed by the coronagraph. Traditionally, atmospheric refraction is compensated for by an atmospheric dispersion compensator (ADC). ADC control relies on an a priori model of the atmosphere whose parameters are solely based on the pointing of the telescope, which can result in imperfect compensation. For a high contrast instrument like the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system, which employs very small IWA coronagraphs, refraction-induced sm...

  16. Discrete dispersion models and their Tweedie asymptotics

    DEFF Research Database (Denmark)

    Jørgensen, Bent; Kokonendji, Célestin C.

    2016-01-01

    approach, whereas several overdispersed discrete distributions, such as the Neyman Type A, Pólya-Aeppli, negative binomial and Poisson-inverse Gaussian, turn out to be Poisson-Tweedie factorial dispersion models with power dispersion functions, analogous to ordinary Tweedie exponential dispersion models...... with power variance functions. Using the factorial cumulant generating function as tool, we introduce a dilation operation as a discrete analogue of scaling, generalizing binomial thinning. The Poisson-Tweedie factorial dispersion models are closed under dilation, which in turn leads to a Poisson...

  17. Modelling airborne dispersion of coarse particulate material

    International Nuclear Information System (INIS)

    Methods of modelling the airborne dispersion and deposition of coarse particulates are presented, with the emphasis on the heavy particles identified as possible constituents of releases from damaged AGR fuel. The first part of this report establishes the physical characteristics of the irradiated particulate in airborne emissions from AGR stations. The second part is less specific and describes procedures for extending current dispersion/deposition models to incorporate a coarse particulate component: the adjustment to plume spread parameters, dispersion from elevated sources and dispersion in conjunction with building effects and plume rise. (author)

  18. Inverse problems using ANN in long range atmospheric dispersion with signature analysis picked scattered numerical sensors from CFD

    International Nuclear Information System (INIS)

    Scalar dispersion in the atmosphere is an important area wherein different approaches are followed in development of good analytical model. The analyses based on Computational Fluid Dynamics (CFD) codes offer an opportunity of model development based on first principles of physics and hence such models have an edge over the existing models. Both forward and backward calculation methods are being developed for atmospheric dispersion around NPPs at BARC Forward modeling methods, which describe the atmospheric transport from sources to receptors, use forward-running transport and dispersion models or computational fluid dynamics models which are run many times, and the resulting dispersion field is compared to observations from multiple sensors. Backward or inverse modeling methods use only one model run in the reverse direction from the receptors to estimate the upwind sources. Inverse modeling methods include adjoint and tangent linear models, Kalman filters, and variational data assimilation, and neural network. The present paper is aimed at developing a new approach where the identified specific signatures at receptor points form the basis for source estimation or inversions. This approach is expected to reduce the large transient data sets to reduced and meaningful data sets. In fact this reduces the inherently transient data set into a time independent mean data set. Forward computation were carried out with CFD code for various case to generate a large set of data to train the ANN. Specific signature analysis was carried out to find the parameters of interest for ANN training like peak concentration, time to reach peak concentration and time to fall, the ANN was trained with data and source strength and location were predicted from ANN. Inverse problem was performed using ANN approach in long range atmospheric dispersion. An illustration of application of CFD code for atmospheric dispersion studies for a hypothetical case is also included in the paper. (author)

  19. Real time analysis for atmospheric dispersions for Fukushima nuclear accident: Mobile phone based cloud computing assessment

    International Nuclear Information System (INIS)

    Highlights: • Possible nuclear accident is simulated for the atmospheric contaminations. • The simulations results give the relative importance of the fallouts. • The cloud computing of IT is performed successfully. • One can prepare for the possible damages of such a NPP accident. • Some other variables can be considered in the modeling. - Abstract: The radioactive material dispersion is investigated by the system dynamics (SD) method. The non-linear complex algorithm could give the information about the hazardous material behavior in the case of nuclear accident. The prevailing westerlies region is modeled for the dynamical consequences of the Fukushima nuclear accident. The event sequence shows the scenario from earthquake to dispersion of the radionuclides. Then, the dispersion reaches two cities in Korea. The importance of the radioactive dispersion is related to the fast and reliable data processing, which could be accomplished by cloud computing concept. The values of multiplications for the wind, plume concentrations, and cloud computing factor are obtained. The highest value is 94.13 in the 206th day for Seoul. In Pusan, the highest value is 15.48 in the 219th day. The source is obtained as dispersion of radionuclide multiplied by 100. The real time safety assessment is accomplished by mobile phone

  20. Wind tunnel modeling of heavy gas dispersion

    Science.gov (United States)

    König-Langlo, G.; Schatzmann, M.

    Assessment of risk attending the manufacturing, storing and transportation of flammable and toxic gases involves the quantification of the ensuing dispersion in case of an accidental release. Worst case considerations have to be applied in order to obtain conservative estimates The paper describes a method for the determination of lower flammability distances for gases heavier than air under unfavorable atmospheric conditions. The method is based on the results of a wind tunnel study investigating the dispersion of instantaneous as well as continuous releases into a boundary-layer shear flow disturbed and undisturbed by surface obstacles. Thermodynamic effects on the dispersing cloud have been taken into account through modification of source parameters. The results have been compared with those from corresponding field trials. The agreement is generally fair. The method has now been converted into a detailed guideline for dispersion calculations within risk assessment studies for flammable and toxic heavy gases (VDI 3783, Part 2, Beuth Verlag, Berlin, 1990).

  1. Case study of the atmospheric dispersion of emissions from UPPR/CDTN, Brazil

    International Nuclear Information System (INIS)

    This work presents a study of the atmospheric dispersion of emissions released during activities of production and research of radiopharmaceuticals in the Center of Nuclear Technology Development (CDTN), localized in Belo Horizonte, Minas Gerais - Brazil. The installation, 'Unidade de Producao e Pesquisa de Radiofarmacos' (UPPR), was considered operating full time during a year. The general goal was to evaluate the radiological environmental impact due to these atmospheric emissions. The pollutants studied were the radionuclides F-18, C-11 and N-13. The meteorological view evaluated was a period of 365 days, simulated from the dates of a typical meteorological year. It was applied the dispersion model ARTM (Atmospheric Radionuclide Transport Model). The atmospheric emissions from UPPR were estimated for the simulation based in an extremely conservative operation condition. Others important data raised and analyzed were: topography, obstacles (buildings) and the land occupation around the CDTN. Among the main results, it is important to emphasize the estimate of the radionuclide concentration and the dose value calculated from these concentration. These results were compared with the dose restriction limit set by the standard CNEN 3.01. Areas of higher concentration were identified and are being used as reference for the positioning of the concentration's monitor of the pollutant by the Radiological Environmental Monitoring Program (PMA). (author)

  2. Case study of the atmospheric dispersion of emissions from UPPR/CDTN, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Barreto, Alberto A.; Cesar, Raisa H.S.; Maleta, Paulo G.M.; Grossi, Pablo A., E-mail: aab@cdtn.br, E-mail: raisa.hsc@gmail.com, E-mail: pgmm@cdtn.br, E-mail: pablo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    This work presents a study of the atmospheric dispersion of emissions released during activities of production and research of radiopharmaceuticals in the Center of Nuclear Technology Development (CDTN), localized in Belo Horizonte, Minas Gerais - Brazil. The installation, 'Unidade de Producao e Pesquisa de Radiofarmacos' (UPPR), was considered operating full time during a year. The general goal was to evaluate the radiological environmental impact due to these atmospheric emissions. The pollutants studied were the radionuclides F-18, C-11 and N-13. The meteorological view evaluated was a period of 365 days, simulated from the dates of a typical meteorological year. It was applied the dispersion model ARTM (Atmospheric Radionuclide Transport Model). The atmospheric emissions from UPPR were estimated for the simulation based in an extremely conservative operation condition. Others important data raised and analyzed were: topography, obstacles (buildings) and the land occupation around the CDTN. Among the main results, it is important to emphasize the estimate of the radionuclide concentration and the dose value calculated from these concentration. These results were compared with the dose restriction limit set by the standard CNEN 3.01. Areas of higher concentration were identified and are being used as reference for the positioning of the concentration's monitor of the pollutant by the Radiological Environmental Monitoring Program (PMA). (author)

  3. Numerical analysis of characteristics of atmospheric dispersion around Tokai nuclear site for emergency plan

    International Nuclear Information System (INIS)

    In order to make an effective countermeasure plan against an accidental release of radioactivity, it is important to grasp characteristics of atmospheric dispersion in objective areas beforehand. This paper describes the numerical analysis of characteristics of atmospheric dispersion and dose distribution in an emergency around the Tokai nuclear site, based on the analysis of observed meteorological data. Analysis of meteorological data at Tokai shows that steady flows from the northeast and land-sea breeze circulations characterize contamination of the land. Results obtained from simulations of atmospheric dispersion under such conditions are: 1) The dose distribution can be represented approximately by Gaussian plume model, when radioactivity is discharged into the steady northeast wind. 2) In the case of a short term release for the period of wind changing from the land to sea breeze, the dose distribution is formed in the shape of an unfolded fun with an angle of approximately 90deg. The high contamination area is sometimes 1.5 times larger than that of the steady wind case. (author)

  4. The Shoreline Environment Atmospheric Dispersion Experiment (SEADEX): Airborne LIDAR data

    International Nuclear Information System (INIS)

    The Shoreline Environment Dispersion Experiment (SEADEX) was a major field experimental program sponsored by the US Nuclear Regulatory Commission (NRC) for the purpose of acquiring a comprehensive, high-quality data base for evaluating models of dispersion within coastal zones. A secondary objective of the program was to provide data to help determine which meteorological measurements are most appropriate for emergency preparedness at nuclear power plant sites. The first field study in this program, SEADEX-I, was conducted in the vicinity of Kewaunee, Wisconsin, on the western shore of Lake Michigan, during the period 28 May-8 June 1982. SRI International was responsible for the design and direction of the field study, as well as for the conduct of some of the measurements. The field-study design included dispersion measurements of oil-fog (aerosol) and SF6 (gas) tracers released simultaneously from the same point, as well as extensive meteorological measurements. This volume covers the airborne lidar data collected by the ALPHA-1 (Airborne Lidar Plume and Haze Analyzer) system operated on board SRI's Queen Air aircraft. The basic ALPHA-1 data consist of vertical cross sections of relative aerosol density within the oil-fog tracer plume, obtained from the down-looking lidar measurements as the aircraft flew over the plume, generally in a cross-plume direction. The vertical cross sections are made up of lidar profiles of relative aerosol obtained at the rate of 5 profiles/sec, which translates to 12 m of horizontal distance between profiles. The lidar data also include measurements of underlying terrain heights, as well as ambient boundary-layer aerosol distributions. 4 refs., 15 figs., 4 tabs

  5. A Model Evaluation of Long-Distance Dispersal of Boll Weevils

    Science.gov (United States)

    Boll weevil eradication programs have progressed toward eradication within each zone, but concerns remain about the possibility of weevil dispersal between eradication zones. In this study, the HYSPLIT atmospheric dispersion model was used to simulate daily wind-aided dispersal of weevils from the ...

  6. Development of atmospheric dispersion module and its integration with diagnostic system for radioactivity release evaluations

    International Nuclear Information System (INIS)

    As a part of development of diagnostic system for accident management in nuclear power plants (NPPs), an atmospheric dispersion module for radioactivity release evaluations using Kalman filter technique has been developed for emergency preparedness. In addition to the accident management, during normal reactor operations, it is desirable to monitor for any aerial releases of radionuclides. These radionuclides incur doses to the surrounding areas when they get carried away by the wind and dispersed in the air due to the turbulence. Normally, the releases from the NPP are in a controlled manner and monitored continuously. However, in case of an accidental release, the quantities may be very uncertain and correct estimation of the release is very important for emergency preparedness and planning in post accident scenarios. In this connection, a Kalman filter technique has been used to estimate the radioactivity release using environmental radiation monitoring data obtained close to the release point. The Kalman filter is a recursive predictor-corrector type estimator. It is based on a state space model in which the state variables, in the current setting, are the parameters of the Gaussian plume model.The plume model parameters, which are collected in the state vector consist of the source term, wind velocity and plume height. The observables consist of simultaneous gamma dose measurements (dose rate) and meteorological data (wind speed) at different times. In this analysis time evolution of the state is represented by the system equation and the measurements are linked to the state variables through the measurement equation. This model has been validated using the data obtained from radiation data acquisition system of a typical Indian nuclear power plant under normal operating conditions. The graphical user interface for atmospheric dispersion calculations has been developed and integrated with the diagnostic system on the high speed computing setup. This module

  7. Can the confidence in long range atmospheric transport models be increased? The Pan-European experience of ensemble

    International Nuclear Information System (INIS)

    Is atmospheric dispersion forecasting an important asset of the early-phase nuclear emergency response management? Is there a 'perfect atmospheric dispersion model'? Is there a way to make the results of dispersion models more reliable and trustworthy? While seeking to answer these questions the multi-model ensemble dispersion forecast system ENSEMBLE will be presented. (authors)

  8. Atmospheric Dispersal and Dispostion of Tephra From a Potential Volcanic Eruption at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    G. Keating; W.Statham

    2004-02-12

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (ASHPLUME) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. The ASHPLUME conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The ASHPLUME mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report will improve and clarify the previous documentation of the ASHPLUME mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model.

  9. Particle dispersion modeling in FFB/pipes

    Energy Technology Data Exchange (ETDEWEB)

    Wu, B.X.; Chang, S.L.; Lottes, S.; Petrick, M. [Academia Sinica, Beijing (China). Multiphase Reaction Lab.

    1995-12-31

    In this paper a new idea on the active behaviour of particles in its dispersion process in fast fluidized beds (FFB)/pipes is presented. Following a review of some preparatory modelling efforts, a new particle dispersion model and, associated with it, a system of particle transport equations suitable for FFB/pipes application are described. The preliminary numerical results verify that the new model is reasonable. 16 refs., 4 figs., 1 tab.

  10. Modeling electrical dispersion phenomena in Earth materials

    Directory of Open Access Journals (Sweden)

    D. Patella

    2008-06-01

    Full Text Available It is illustrated that IP phenomena in rocks can be described using conductivity dispersion models deduced as solutions to a 2nd-order linear differential equation describing the motion of a charged particle immersed in an external electrical field. Five dispersion laws are discussed, namely: the non-resonant positive IP model, which leads to the classical Debye-type dispersion law and by extension to the Cole-Cole model, largely used in current practice; the non-resonant negative IP model, which allows negative chargeability values, known in metals at high frequencies, to be explained as an intrinsic physical property of earth materials in specific field cases; the resonant flat, positive or negative IP models, which can explain the presence of peak effects at specific frequencies superimposed on flat, positive or negative dispersion spectra.

  11. Predictability of the dispersion of Fukushima-derived radionuclides and their homogenization in the atmosphere.

    Science.gov (United States)

    Mészáros, Róbert; Leelőssy, Ádám; Kovács, Tibor; Lagzi, István

    2016-01-01

    Long-range simulation of the dispersion of air pollutants in the atmosphere is one of the most challenging tasks in geosciences. Application of precise and fast numerical models in risk management and decision support can save human lives and can diminish consequences of an accidental release. Disaster at Fukushima Daiichi nuclear power plant has been the most serious event in the nuclear technology and industry in the recent years. We present and discuss the results of the numerical simulations on dispersion of Fukushima-derived particulate (131)I and (137)Cs using a global scale Lagrangian particle model. We compare concentrations and arrival times, using two emission scenarios, with the measured data obtained from 182 monitoring stations located all over the Northern Hemisphere. We also investigate the homogenization of isotopes in the atmosphere. Peak concentrations were predicted with typical accuracy of one order of magnitude showing a general underestimation in the case of (131)I but not for (137)Cs. Tropical and Arctic plumes, as well as the early detections in American and European midlatitudes were generally well predicted, however, the later regional-scale mixing could not be captured by the model. Our investigation highlights the importance of the parameterization of free atmospheric turbulence. PMID:26817513

  12. Predictability of the dispersion of Fukushima-derived radionuclides and their homogenization in the atmosphere

    Science.gov (United States)

    Mészáros, Róbert; Leelőssy, Ádám; Kovács, Tibor; Lagzi, István

    2016-01-01

    Long-range simulation of the dispersion of air pollutants in the atmosphere is one of the most challenging tasks in geosciences. Application of precise and fast numerical models in risk management and decision support can save human lives and can diminish consequences of an accidental release. Disaster at Fukushima Daiichi nuclear power plant has been the most serious event in the nuclear technology and industry in the recent years. We present and discuss the results of the numerical simulations on dispersion of Fukushima-derived particulate 131I and 137Cs using a global scale Lagrangian particle model. We compare concentrations and arrival times, using two emission scenarios, with the measured data obtained from 182 monitoring stations located all over the Northern Hemisphere. We also investigate the homogenization of isotopes in the atmosphere. Peak concentrations were predicted with typical accuracy of one order of magnitude showing a general underestimation in the case of 131I but not for 137Cs. Tropical and Arctic plumes, as well as the early detections in American and European midlatitudes were generally well predicted, however, the later regional-scale mixing could not be captured by the model. Our investigation highlights the importance of the parameterization of free atmospheric turbulence.

  13. ATMOSPHERIC DISPERSAL AND DEPOSITION OF TEPHRA FROM A POTENTIAL VOLCANIC ERUPTION AT YUCCA MOUNTAIN, NEVADA

    Energy Technology Data Exchange (ETDEWEB)

    C. Harrington

    2004-10-25

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (Ashplume) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. These aspects of volcanism-related dose calculation are described in the context of the entire igneous disruptive events conceptual model in ''Characterize Framework for Igneous Activity'' (BSC 2004 [DIRS 169989], Section 6.1.1). The Ashplume conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The Ashplume mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report update the previous documentation of the Ashplume mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model. In this report, ''Ashplume'' is used when referring to the atmospheric dispersal model and ''ASHPLUME'' is used when referencing the code of that model. Two analysis and model reports provide direct inputs to this model report, namely ''Characterize Eruptive Processes at Yucca Mountain, Nevada and Number of Waste Packages Hit

  14. ATMOSPHERIC DISPERSAL AND DEPOSITION OF TEPHRA FROM A POTENTIAL VOLCANIC ERUPTION AT YUCCA MOUNTAIN, NEVADA

    International Nuclear Information System (INIS)

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (Ashplume) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. These aspects of volcanism-related dose calculation are described in the context of the entire igneous disruptive events conceptual model in ''Characterize Framework for Igneous Activity'' (BSC 2004 [DIRS 169989], Section 6.1.1). The Ashplume conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The Ashplume mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report update the previous documentation of the Ashplume mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model. In this report, ''Ashplume'' is used when referring to the atmospheric dispersal model and ''ASHPLUME'' is used when referencing the code of that model. Two analysis and model reports provide direct inputs to this model report, namely ''Characterize Eruptive Processes at Yucca Mountain, Nevada and Number of Waste Packages Hit by Igneous Intrusion''. This model report provides direct inputs to

  15. A dispersion modelling system for urban air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Karppinen, A.; Kukkonen, J.; Nordlund, G.; Rantakrans, E.; Valkama, I.

    1998-10-01

    An Urban Dispersion Modelling system UDM-FMI, developed at the Finnish Meteorological Institute is described in the report. The modelling system includes a multiple source Gaussian plume model and a meteorological pre-processing model. The dispersion model is an integrated urban scale model, taking into account of all source categories (point, line, area and volume sources). It includes a treatment of chemical transformation (for NO{sub 2}) wet and dry deposition (for SO{sub 2}) plume rise, downwash phenomena and dispersion of inert particles. The model allows also for the influence of a finite mixing height. The model structure is mainly based on the state-of-the-art methodology. The system also computes statistical parameters from the time series, which can be compared to air quality guidelines. The relevant meteorological parameters for the dispersion model are evaluated using data produced by a meteorological pre-processor. The model is based mainly on the energy budget method. Results of national investigations have been used for evaluating climate-dependent parameters. The model utilises the synoptic meteorological observations, radiation records and aerological sounding observations. The model results include the hourly time series of the relevant atmospheric turbulence 51 refs.

  16. Physical models of polarization mode dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Menyuk, C.R.; Wai, P.K.A. [Univ. of Maryland, Baltimore, MD (United States)

    1995-12-31

    The effect of randomly varying birefringence on light propagation in optical fibers is studied theoretically in the parameter regime that will be used for long-distance communications. In this regime, the birefringence is large and varies very rapidly in comparison to the nonlinear and dispersive scale lengths. We determine the polarization mode dispersion, and we show that physically realistic models yield the same result for polarization mode dispersion as earlier heuristic models that were introduced by Poole. We also prove an ergodic theorem.

  17. Modeling 137CS dispersion from a radiological dispersion device

    International Nuclear Information System (INIS)

    This analysis reveals that, if terrorists detonate a RDD containing a relatively small amount of 137Cs (approximately 12-35g), the resulting dispersion can contaminate a relatively large area. The actual magnitude of a terrorist incident involving the release of radioactive material by a dirty bomb depends on the dimensions of the contaminated area and the accompanying contamination density (i.e., radioactivity) distributed within that area. Applying a semiempirical model indicates that the spatial extent of the contaminated area and the level of activity within that area are dependent primarily on local scale meteorological conditions, especially whether rainfall occurs, as well particle size and effective release height. As a result, the magnitude of the consequences of terrorists acquiring non-weapons grade nuclear materials and releasing those materials with a dirty bomb is contingent on a number of factors beyond the scope of active countermeasures, especially the RDD's design elements and local-scale meteorological conditions. Modeling the dispersion of radioactive aerosols throughout an urban landscape, especially with accurate 3-D representation of its complex geometry and meteorology, is indispensable for assessing the potential consequences of a terrorist incident and implementing effective emergency response, health services, and decontamination decisions. (orig.)

  18. Atmospheric dispersion of PCB from a contaminated Lake Michigan harbor

    Science.gov (United States)

    Martinez, Andres; Spak, Scott N.; Petrich, Nicholas T.; Hu, Dingfei; Carmichael, Gregory R.; Hornbuckle, Keri C.

    2015-12-01

    Indiana Harbor and Ship Canal (IHSC) in East Chicago is an industrial waterway on Lake Michigan and a source of PCBs to Lake Michigan and the overlying air. We hypothesized that IHSC is an important source of airborne PCBs to surrounding communities. We used AERMOD to model hourly PCB concentrations, utilizing emission fluxes from a prior study and hourly meteorology provided by the State of Indiana. We also assessed dispersion using hourly observed meteorology from a local airport and high resolution profiles simulated by the Weather Research and Forecasting model. We found that emissions from IHSC waters contributed about 15% of the observed ∑PCB concentrations close to IHSC when compared on an hourly basis and about 10% of observed annual concentrations at a nearby school. Concentrations at the school due to emissions from IHSC ranged from 0 to 18,000 pg m-3, up to 20 times higher than observed background levels, with an annual geometric mean (GSD) of 19 (31) pg m-3. Our findings indicate that IHSC is an important source of PCBs to East Chicago, but not the only source. Four observed enriched PCB3 samples suggest a nearby non-Aroclor source.

  19. Kalman filtration of radiation monitoring data from atmospheric dispersion of radioactive materials

    DEFF Research Database (Denmark)

    Drews, M.; Lauritzen, B.; Madsen, H.;

    2004-01-01

    A Kalman filter method using off-site radiation monitoring data is proposed as a tool for on-line estimation of the source term for short-range atmospheric dispersion of radioactive materials. The method is based on the Gaussian plume model, in which the plume parameters including the source term...... exhibit a ‘random walk’ process. The embedded parameters of the Kalman filter are determined through maximum-likelihood estimation making the filter essentially free of external parameters. The method is tested using both real and simulated radiation monitoring data. For simulated data, the method is...

  20. NKS-B NordRisk II: Nuclear risk from atmospheric dispersion in Northern Europe - Summary report

    International Nuclear Information System (INIS)

    The objective of the NordRisk II project has been to derive practical means for assessing the risks from long-range atmospheric dispersion of radioactive materials. An atlas over different atmospheric dispersion and deposition scenarios has been developed using historical numerical weather prediction (NWP) model data. The NWP model data covers three years spanning the climate variability associated with the North Atlantic Oscillation, and the atlas considers radioactive releases from 16 release sites in and near the Nordic countries. A statistical analysis of the long-range dispersion and deposition patterns is undertaken to quantify the mean dispersion and deposition as well as the variability. Preliminary analyses show that the large-scale atmospheric dispersion and deposition is near-isotropic, irrespective of the release site and detailed climatology, and allows for a simple parameterization of the global dispersion and deposition patterns. The atlas and the underlying data are made available in a format compatible with the ARGOS decision support system, and have been implemented in ARGOS. (Author)

  1. Dispersive infrared spectroscopy measurements of atmospheric CO2 using a Fabry–Pérot interferometer sensor

    International Nuclear Information System (INIS)

    In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO2) using a new scanning Fabry–Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3900 nm to 5220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO2 absorption band (∼ 4280 nm) and sampling resolution of 20 nm. The CO2 concentration is determined from the measured optical absorption spectra by fitting it to the CO2 reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H2O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO2 measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO2 measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO2 analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO2 measurement featuring high accuracy, correction of non-linear absorption and interference of water vapor. - Highlights: • Dispersive infrared

  2. Implementation of a model of atmospheric dispersion and dose calculation in the release of radioactive effluents in the Nuclear Centre; Implementacion de un modelo de dispersion atmosferica y calculo de dosis en la liberacion de efluentes radiactivos en el Centro Nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Cruz L, C. A.

    2015-07-01

    In the present thesis, the software DERA (Dispersion of Radioactive Effluents into the Atmosphere) was developed in order to calculate the equivalent dose, external and internal, associated with the release of radioactive effluents into the atmosphere from a nuclear facility. The software describes such emissions in normal operation, and not considering the exceptional situations such as accidents. Several tools were integrated for describing the dispersion of radioactive effluents using site meteorological information (average speed and wind direction and the stability profile). Starting with the calculation of the concentration of the effluent as a function of position, DERA estimates equivalent doses using a set of EPA s and ICRP s coefficients. The software contains a module that integrates a database with these coefficients for a set of 825 different radioisotopes and uses the Gaussian method to calculate the effluents dispersion. This work analyzes how adequate is the Gaussian model to describe emissions type -puff-. Chapter 4 concludes, on the basis of a comparison of the recommended correlations of emissions type -puff-, that under certain conditions (in particular with intermittent emissions) it is possible to perform an adequate description using the Gaussian model. The dispersion coefficients (σ{sub y} and σ{sub z}), that using the Gaussian model, were obtained from different correlations given in the literature. Also in Chapter 5 is presented the construction of a particular correlation using Lagrange polynomials, which takes information from the Pasquill-Gifford-Turner curves (PGT). This work also contains a state of the art about the coefficients that relate the concentration with the equivalent dose. This topic is discussed in Chapter 6, including a brief description of the biological-compartmental models developed by the ICRP. The software s development was performed using the programming language Python 2.7, for the Windows operating system (the

  3. Relation between Dispersion Characteristics over Surfaces with Dissimilar Roughness and Atmospheric Stability, under Conditions of Equal Geostrophic Winds

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Larsen, Søren Ejling

    1981-01-01

    A simple model was described that related the dispersion of material from ground-level sources at 2 areas, taking into account dissimilarities in the surface roughness parameter (z0) and the atmospheric stability characterized by the Monin-Obukhov length (L). The geostrophic wind speed was assumed...

  4. Simple model of the flow and dispersion over urban area

    Czech Academy of Sciences Publication Activity Database

    Jaňour, Zbyněk; Bezpalcová, Klára; Šeděnková, H.

    Karlsruhe : Forshungszentrum Karlsruhe GmbH, 2004 - (Suppan P.), s. 55-59 ISBN 3-923704-45-3. [Harmonisation within atmospheric Dispersion modeling for regulatory purposes. Garmisch-Partenkirchen (DE), 01.06.2004-04.06.2004] R&D Projects: GA MŠk OC 715.10; GA ČR GA205/04/0311 Grant ostatní: XC(CZ) NATO EST-CLG-979863 Institutional research plan: CEZ:AV0Z2076919 Keywords : boundary layer * atmosphere * urban Subject RIV: BK - Fluid Dynamics

  5. Modeling pollutants dispersion in surrounding places to thermoelectric power plants

    International Nuclear Information System (INIS)

    In the Electrical Research Institute (IIE) have been carried out some studies on determination of concentration levels of atmospheric pollutants in areas where is located some thermoelectric central of the Electricity Federal Commission (CFE). These studies have as main objective to collect judgement elements that allow to take measurements for avoiding the environmental damage. At the present time it has been performed modelations of dispersion of atmospheric pollutants on surroundings of thermoelectric centrals, such as Lerdo, Manzanillo, Mazatlan, Monterrey, Rio Escondido, Salamanca, Mexico and Tula's Valley. Therefore in the present work has been included some generalities about the experiences gained in those studies. (Author)

  6. Atmospheric Dispersion Unknown Source Parameters Determination Using AERMOD and Bayesian Inference Along Markov Chain Monte Carlo

    International Nuclear Information System (INIS)

    Occurrence of hazardous accident in nuclear power plants and industrial units usually lead to release of radioactive materials and pollutants in environment. These materials and pollutants can be transported to a far downstream by the wind flow. In this paper, we implemented an atmospheric dispersion code to solve the inverse problem. Having received and detected the pollutants in one region, we may estimate the rate and location of the unknown source. For the modeling, one needs a model with ability of atmospheric dispersion calculation. Furthermore, it is required to implement a mathematical approach to infer the source location and the related rates. In this paper the AERMOD software and Bayesian inference along the Markov Chain Monte Carlo have been applied. Implementing, Bayesian approach and Markov Chain Monte Carlo for the aforementioned subject is not a new approach, but the AERMOD model coupled with the said methods is a new and well known regulatory software, and enhances the reliability of outcomes. To evaluate the method, an example is considered by defining pollutants concentration in a specific region and then obtaining the source location and intensity by a direct calculation. The result of the calculation estimates the average source location at a distance of 7km with an accuracy of 5m which is good enough to support the ability of the proposed algorithm.

  7. Analysis and demonstration of atmospheric methane monitoring by mid-infrared open-path chirped laser dispersion spectroscopy.

    Science.gov (United States)

    Daghestani, Nart S; Brownsword, Richard; Weidmann, Damien

    2014-12-15

    Atmospheric methane concentration levels were detected using a custom built laser dispersion spectrometer in a long open-path beam configuration. The instrument is driven by a chirped distributed feedback mid-infrared quantum cascade laser centered at ~1283.46 cm-1 and covers intense rotational-vibrational transitions from the fundamental ν4 band of methane. A full forward model simulating molecular absorption and dispersion profiles, as well as instrumental noise, is demonstrated. The instrument's analytical model is validated and used for quantitative instrumental optimization. The temporal evolution of atmospheric methane mixing ratios is retrieved using a fitting algorithm based on the model. Full error propagation analysis on precision gives a normalized sensitivity of ~3 ppm.m.Hz-0.5 for atmospheric methane. PMID:25607487

  8. Operational mesoscale atmospheric dispersion prediction using high performance parallel computing cluster for emergency response

    International Nuclear Information System (INIS)

    An operational atmospheric dispersion prediction system is implemented on a cluster super computer for 'Online Emergency Response' for Kalpakkam nuclear site. The numerical system constitutes a parallel version of a nested grid meso-scale meteorological model MM5 coupled to a random walk particle dispersion model FLEXPART. The system provides 48 hour forecast of the local weather and radioactive plume dispersion due to hypothetical air borne releases in a range of 100 km around the site. The parallel code was implemented on different cluster configurations like distributed and shared memory systems. Results of MM5 run time performance for 1-day prediction are reported on all the machines available for testing. A reduction of 5 times in runtime is achieved using 9 dual Xeon nodes (18 physical/36 logical processors) compared to a single node sequential run. Based on the above run time results a cluster computer facility with 9-node Dual Xeon is commissioned at IGCAR for model operation. The run time of a triple nested domain MM5 is about 4 h for 24 h forecast. The system has been operated continuously for a few months and results were ported on the IMSc home page. Initial and periodic boundary condition data for MM5 are provided by NCMRWF, New Delhi. An alternative source is found to be NCEP, USA. These two sources provide the input data to the operational models at different spatial and temporal resolutions and using different assimilation methods. A comparative study on the results of forecast is presented using these two data sources for present operational use. Slight improvement is noticed in rainfall, winds, geopotential heights and the vertical atmospheric structure while using NCEP data probably because of its high spatial and temporal resolution. (author)

  9. Models of oil spill dispersion stability

    International Nuclear Information System (INIS)

    This paper summarized the theory of oil-in-water emulsion stability resulting in the resurfacing of oil spill dispersion. Since most emulsions are unstable, they will break down into their constituent parts because of the many forces and processes that act on them. These include gravitational forces; surfactant interchange with water and the subsequent surfactant loss to the water column; creaming; coalescence; flocculation; Ostwald ripening; and sedimentation. Gravitational separation is the most important force that contributes to the resurfacing of oil droplets from an oil-in-water emulsion. The paper presented a newly developed model that used 4 basic processes. Initial dispersion was an input, then the dispersion was distributed over the mixing depth, as predicted by the wave height. The droplets then rise to the surface according to Stokes' law. Oil on the surface from the rising oil and undispersed oil is redispersed. The droplets in the water column are subject to coalescence as governed by the Smoluchowski equation. The dispersion in the water column therefore decreases at an exponential rate with dispersion half-lives ranging from 120 to 250 minutes. Over 200 runs were performed using variations of the models. The study showed that the most important factor is the effectiveness of the initial dispersion and the the redispersion. Increased sea energy was found to increase the amount of coalescence that occurs, resulting in an increase in resurfacing. However, increased turbulence also caused redispersion, offsetting the effect of the recoalescence slightly. 17 refs., 5 tabs., 13 figs.

  10. Models of oil spill dispersion stability

    Energy Technology Data Exchange (ETDEWEB)

    Fingas, M. [Spill Science, Edmonton, AB (Canada)

    2009-07-01

    This paper summarized the theory of oil-in-water emulsion stability resulting in the resurfacing of oil spill dispersion. Since most emulsions are unstable, they will break down into their constituent parts because of the many forces and processes that act on them. These include gravitational forces; surfactant interchange with water and the subsequent surfactant loss to the water column; creaming; coalescence; flocculation; Ostwald ripening; and sedimentation. Gravitational separation is the most important force that contributes to the resurfacing of oil droplets from an oil-in-water emulsion. The paper presented a newly developed model that used 4 basic processes. Initial dispersion was an input, then the dispersion was distributed over the mixing depth, as predicted by the wave height. The droplets then rise to the surface according to Stokes' law. Oil on the surface from the rising oil and undispersed oil is redispersed. The droplets in the water column are subject to coalescence as governed by the Smoluchowski equation. The dispersion in the water column therefore decreases at an exponential rate with dispersion half-lives ranging from 120 to 250 minutes. Over 200 runs were performed using variations of the models. The study showed that the most important factor is the effectiveness of the initial dispersion and the the redispersion. Increased sea energy was found to increase the amount of coalescence that occurs, resulting in an increase in resurfacing. However, increased turbulence also caused redispersion, offsetting the effect of the recoalescence slightly. 17 refs., 5 tabs., 13 figs.

  11. First look at the new ARAC dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Leone, J.M., Jr.; Nasstrom, J.S.; Maddix, D.M.

    1996-11-01

    We describe a new atmospheric dispersion model being developed for the emergency response system of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC). This model solves the turbulent, advection-diffusion equation via a Lagrangian particle, Monte-Carlo method. Within a simulation, particles representing the pollutant are moved through the domain using a random displacement method to model the turbulent diffusion and a Runge-Kutta method to model the advection. The bottom boundary in the new model is a union of bilinear surfaces between gridded terrain data rather than the discontinuous `stair step` representation of terrain used previously in the ARAC. The new model accepts winds on (x,y,o) grids that can be horizontally and vertically graded and nested in the horizontal.

  12. Numerical simulation and variational data assimilation for atmospheric dispersion of pollutants

    International Nuclear Information System (INIS)

    This work has led to the development of a three-dimensional chemistry-transport model Polair3D which simulates photochemistry. Model-to-data comparison of ozone and nitrogen oxides measurements over the city of Lille in 1998 has proven its reliability at regional scale. 4-dimensional-variational data assimilation has been implemented. It relies on the adjoint model of Polair3D obtained through automatic differentiation. An application of inverse modelling of emissions over Lille city with real measurements has been performed. It has proven that the inversion of temporal parameters of nitrogen oxides emissions leads to a significant improvement of forecasts. The so-called second-order sensitivity allows the study of the sensitivity of the inversion with respect to the data assimilation system itself by computing its conditioning. This is illustrated by two test cases: short-range dispersion of radionuclides and gas-phase atmospheric chemistry characterized by a wide range of timescales. (author)

  13. The Infrared Imaging Spectrograph (IRIS) for TMT: the atmospheric dispersion corrector

    CERN Document Server

    Phillips, Andrew C; Larkin, James E; Moore, Anna M; Niehaus, Cynthia N; Cramptone, David; Simard, Luc

    2010-01-01

    We present a conceptual design for the atmospheric dispersion corrector (ADC) for TMT's Infrared Imaging Spectrograph (IRIS). The severe requirements of this ADC are reviewed, as are limitations to observing caused by uncorrectable atmospheric effects. The requirement of residual dispersion less than 1 milliarcsecond can be met with certain glass combinations. The design decisions are discussed and the performance of the design ADC is described. Alternative options and their performance tradeoffs are also presented.

  14. Quantification of uncertainties in ETEX dispersion modelling using ensemble forecasts

    International Nuclear Information System (INIS)

    A tracer dispersion model, the Severe Nuclear Accident Program (SNAP), developed and operated at the Norwegian Meteorological Institute, is used to investigate the effect of errors in meteorological input data due to analysis errors. An ensemble forecast, produced at the European Centre for Medium-Range Weather Forecasts (ECMWF), is an attempt to represent possible forecast developments due to analysis errors. 33 puff dispersions are produced by SNAP, using input from one such ensemble of forecasts. The puff dispersions are compared, and a large spread among them is found. This shows that the quality of the meteorological data is important for the success of dispersion models. In order to evaluate the SNAP model, one of its puff predictions is compared with measurements from the European Tracer Experiment (ETEX). The model manages to predict the measured puff evolution concerning shape and time of arrival to a fairly high extent, up to 60 hours after the start of the release. The modelled puff is too narrow in the advection direction though. The SNAP models description of the mixing processes within the atmospheric boundary layer therefore probably needs to be revised. (author)

  15. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...

  16. Harmonization in the pre-processing of meteorological data for dispersion models

    International Nuclear Information System (INIS)

    It is suggested that the National Meteorological Services should attempt to coordinate the methods they will use to provide the data for predicting atmospheric dispersion models regarding air pollution. Standard data need significant processing in order to provide the fundamental parameters which will eventually represent meteorological influences in all methods of dispersion prediction. The paper outlines a framework intended to lead to uniform responses to the requirements of dispersion modellers'. (AB)

  17. Titan atmospheric models intercomparison

    Science.gov (United States)

    Pernot, P.

    2008-09-01

    Several groups over the world have developed independently models of the photochemistry of Titan. The Cassini mission reveals daily that the chemical complexity is beyond our expectations e. g. observation of heavy positive and negative ions..., and the models are updated accordingly. At this stage, there is no consensus on the various input parameters, and it becomes increasingly difficult to compare outputs form different models. An ISSI team of experts of those models will be gathered shortly to proceed to an intercomparison, i.e. to assess how the models behave, given identical sets of inputs (collectively defined). Expected discrepancies will have to be elucidated and reduced. This intercomparison will also be an occasion to estimate explicitly the importance of various physicalchemical processes on model predictions versus observations. More robust and validated models are expected from this study for the interpretation of Titanrelated data.

  18. Hanford atmospheric dispersion data: 1960 through June 1967

    Energy Technology Data Exchange (ETDEWEB)

    Nickola, P.W.; Ramsdell, J.V.; Glantz, C.S.; Kerns, R.E.

    1983-11-01

    This volume presents dispersion and supporting meteorological data from experiments conducted over relatively flat terrain at Hanford, Washington from January 1960 through June 1967. The nature of the experiments, the sampling grids, and the tracer techniques used are described in the narrative portion of the document. Appendices contain the time-integrated concentrations for samplers within the plumes, summaries of the concentration distributions across the plumes, and wind and temperature profile data for each release period. 18 references, 7 figures, 3 tables.

  19. Iterative ensemble Kalman filter for atmospheric dispersion in nuclear accidents: An application to Kincaid tracer experiment.

    Science.gov (United States)

    Zhang, X L; Su, G F; Chen, J G; Raskob, W; Yuan, H Y; Huang, Q Y

    2015-10-30

    Information about atmospheric dispersion of radionuclides is vitally important for planning effective countermeasures during nuclear accidents. Results of dispersion models have high spatial and temporal resolutions, but they are not accurate enough due to the uncertain source term and the errors in meteorological data. Environmental measurements are more reliable, but they are scarce and unable to give forecasts. In this study, our newly proposed iterative ensemble Kalman filter (EnKF) data assimilation scheme is used to combine model results and environmental measurements. The system is thoroughly validated against the observations in the Kincaid tracer experiment. The initial first-guess emissions are assumed to be six magnitudes underestimated. The iterative EnKF system rapidly corrects the errors in the emission rate and wind data, thereby significantly improving the model results (>80% reduction of the normalized mean square error, r=0.71). Sensitivity tests are conducted to investigate the influence of meteorological parameters. The results indicate that the system is sensitive to boundary layer height. When the heights from the numerical weather prediction model are used, only 62.5% of reconstructed emission rates are within a factor two of the actual emissions. This increases to 87.5% when the heights derived from the on-site observations are used. PMID:26026852

  20. Debris Dispersion Model Using Java 3D

    Science.gov (United States)

    Thirumalainambi, Rajkumar; Bardina, Jorge

    2004-01-01

    This paper describes web based simulation of Shuttle launch operations and debris dispersion. Java 3D graphics provides geometric and visual content with suitable mathematical model and behaviors of Shuttle launch. Because the model is so heterogeneous and interrelated with various factors, 3D graphics combined with physical models provides mechanisms to understand the complexity of launch and range operations. The main focus in the modeling and simulation covers orbital dynamics and range safety. Range safety areas include destruct limit lines, telemetry and tracking and population risk near range. If there is an explosion of Shuttle during launch, debris dispersion is explained. The shuttle launch and range operations in this paper are discussed based on the operations from Kennedy Space Center, Florida, USA.

  1. Kalman filtration of radiation monitoring data from atmospheric dispersion of radioactive materials

    International Nuclear Information System (INIS)

    A Kalman filter method using off-site radiation monitoring data is proposed as a tool for on-line estimation of the source term for short-range atmospheric dispersion of radioactive materials. The method is based on the Gaussian plume model, in which the plume parameters including the source term exhibit a 'random walk' process. The embedded parameters of the Kalman filter are determined through maximum-likelihood estimation making the filter essentially free of external parameters. The method is tested using both real and simulated radiation monitoring data. For simulated data, the method is shown to retrieve the embedded parameters employed in generating the data and to reconstruct the plume model parameters, including the source term. When tested against experimental radiation monitoring data the method is found accurately to uncover the known source term. (authors)

  2. Dispersion modeling of thermal power plant emissions on stochastic space

    Science.gov (United States)

    Gorle, J. M. R.; Sambana, N. R.

    2016-05-01

    This study aims to couple a deterministic atmospheric dispersion solver based on Gaussian model with a nonintrusive stochastic model to quantify the propagation of multiple uncertainties. The nonintrusive model is based on probabilistic collocation framework. The advantage of nonintrusive nature is to retain the existing deterministic plume dispersion model without missing the accuracy in extracting the statistics of stochastic solution. The developed model is applied to analyze the SO2 emission released from coal firing unit in the second stage of the National Thermal Power Corporation (NTPC) in Dadri, India using "urban" conditions. The entire application is split into two cases, depending on the source of uncertainty. In case 1, the uncertainties in stack gas exit conditions are used to construct the stochastic space while in case 2, meteorological conditions are considered as the sources of uncertainty. Both cases develop 2D uncertain random space in which the uncertainty propagation is quantified in terms of plume rise and pollutant concentration distribution under slightly unstable atmospheric stability conditions. Starting with deterministic Gaussian plume model demonstration and its application, development of stochastic collocation model, convergence study, error analysis, and uncertainty quantification are presented in this paper.

  3. Simulation of the atmospheric dispersion at local scale in the area of Cogema (la Hague) using PERLE system

    International Nuclear Information System (INIS)

    METEO-FRANCE is presently developing a new system named PERLE which permits real time evaluation of atmospheric dispersion at local scale. This system consists in a non-hydrostatic meteorological model at mezo-scale (Meso-NH) and a particular code for the dispersion of the chemically passive pollutants. As a result of several studies performed by DP/SERV/ENV at Meteo-France, two particular codes have been retained for the dispersion module of PERLE: DIFPAR (EDF) and SPRAY (Aria Technologies). In this study, the dispersion at local scale of Kr 85 in the area of the nuclear-wastes reprocessing plant COGEMA (La Hague) has been simulated with the two dispersion models, initialised with the meteorological fields provided by Meso-NH. The simulations concern the most complete sampling campaign of Kr 85 performed in this area on 18th and 19th september 2001. The evaluation the two models performances and of the PERLE system's results for this campaign has been done by using the CTA (Atmospherical Transfer Coefficient) measured values. (authors)

  4. Modeling of uncertainty in atmospheric transport system using hybrid method

    International Nuclear Information System (INIS)

    Atmospheric dispersion models are routinely used at nuclear and chemical plants to estimate exposure to the members of the public and occupational workers due to release of hazardous contaminants into the atmosphere. Atmospheric dispersion is a stochastic phenomenon and in general, the concentration of the contaminant estimated at a given time and at a predetermined location downwind of a source cannot be predicted precisely. Uncertainty in atmospheric dispersion model predictions is associated with: 'data' or 'parameter' uncertainty resulting from errors in the data used to execute and evaluate the model, uncertainties in empirical model parameters, and initial and boundary conditions; 'model' or 'structural' uncertainty arising from inaccurate treatment of dynamical and chemical processes, approximate numerical solutions, and internal model errors; and 'stochastic' uncertainty, which results from the turbulent nature of the atmosphere as well as from unpredictability of human activities related to emissions, The possibility theory based on fuzzy measure has been proposed in recent years as an alternative approach to address knowledge uncertainty of a model in situations where available information is too vague to represent the parameters statistically. The paper presents a novel approach (called Hybrid Method) to model knowledge uncertainty in a physical system by a combination of probabilistic and possibilistic representation of parametric uncertainties. As a case study, the proposed approach is applied for estimating the ground level concentration of hazardous contaminant in air due to atmospheric releases through the stack (chimney) of a nuclear plant. The application illustrates the potential of the proposed approach. (author)

  5. Integration of dispersion and radio ecological modelling in ARGOS NT

    International Nuclear Information System (INIS)

    The Danish development ARGOS NT system is in operation in Denmark and 5 Baltic Sea states. Based on data from 40 advanced early warning stations - PMS stations - and various other monitoring sources the ARGOS NT system provides an excellent basis for decision. ARGOS NT is a dynamic system that is modified regularly in order to cope with new requirements. The present version of the system includes features such as: dynamical presentation facilities for the EURDEP data exchange format, presentation of high spatial resolution data and isotropic information from the Danish Airborne monitoring systems. The new version of the system includes a module for simulating food chain transfer and dose assessment. It is based on the radioecological model ECOSYS. This model has been initially developed for German conditions; therefore it is necessary to adapt it to the conditions of those countries where ARGOS-NT is applied. Concentration of radioactivity in foodstuffs (crops and animal products) as a function of time is the endpoint of the food chain part. Doses from internal exposure (ingestion, inhalation) and external exposure can be estimated for different age groups. Rough estimations of collective dose can be made if the necessary data is available. Further a new dispersion module called MET-DISP has been integrated. Met-DISP is a comprehensive meteorological dispersion forecast module for emergency response. MET-DISP is designed to provide forecasts of dispersion, gamma doses and deposition from releases of radioactive material on local, national and continental scales. The module enables real-time forecasts via a set of local scale wind and atmospheric dispersion models that are driven by on-line available meteorological information. Meteorological information is made available to the system either via on-line connections to local meteorological observations (met-towers and sodars) or via on-line network connections to Meteorological Services. The system provides forecast

  6. MARCS model atmospheres

    CERN Document Server

    Plez, Bertrand

    2008-01-01

    In this review presented at the Symposium A stellar journey in Uppsala, June 2008, I give my account of the historical development of the MARCS code from the first version published in 1975 and its premises to the 2008 grid. It is shown that the primary driver for the development team is the science that can be done with the models, and that they constantly strive to include the best possible physical data. A few preliminary comparisons of M star model spectra to spectrophotometric observations are presented. Particular results related to opacity effects are discussed. The size of errors in the spectral energy distribution (SED) and model thermal stratification are estimated for different densities of the wavelength sampling. The number of points used in the MARCS 2008 grid (108000) is large enough to ensure errors of only a few K in all models of the grid, except the optically very thin layers of metal-poor stars. Errors in SEDs may reach about 10% locally in the UV. The published sampled SEDs are thus appro...

  7. Probabilistic siting analysis of nuclear power plants emphasizing atmospheric dispersion of radioactive releases and radiation-induced health effects

    International Nuclear Information System (INIS)

    A presentation is made of probabilistic evaluation schemes for nuclear power plant siting. Effects on health attributable to ionizing radiation are reviewed, for the purpose of assessment of the numbers of the most important health effect cases in light-water reactor accidents. The atmospheric dispersion of radioactive releases from nuclear power plants is discussed, and there is presented an environmental consequence assessment model in which the radioactive releases and atmospheric dispersion of the releases are treated by the application of probabilistic methods. In the model, the environmental effects arising from exposure to radiation are expressed as cumulative probability distributions and expectation values. The probabilistic environmental consequence assessment model has been applied to nuclear power plant site evaluation, including risk-benefit and cost-benefit analyses, and the comparison of various alternative sites. (author)

  8. Atmospheric dispersal of 129iodine from nuclear fuel reprocessing facilities

    International Nuclear Information System (INIS)

    129I/127I ratios measured in meteoric water and epiphytes from the continental United States are higher than those measured in coastal seawater or surface freshwater and suggest long-range atmospheric transport of 129I from the main source for the earth's surface inventory, viz., nuclear fuel reprocessing facilities. The median ratio for 14 meteoric water samples is 2100 x 10-12, corresponding to a 129I concentration of 2.5 x 107 atoms/L, whereas 9 epiphyte samples have a median ratio of 1800 x 10-12. Calculated deposition rates of 129I in the continental United States reveal that a small but significant fraction of the atmospheric releases from the nuclear fuel reprocessing facilities at Sellafield, England, and Cap de La Hague, France, is deposited after distribution by long-range transport. The inferred dominant mode of transport is easterly, within the troposphere, mainly in the form of the organic gas methyl iodide

  9. Mesoscale constitutive modeling of magnetic dispersions.

    Science.gov (United States)

    Bhandar, Anand S; Wiest, John M

    2003-01-15

    A constitutive model for dispersions of acicular magnetic particles has been developed by modeling the particles as rigid dumbbells dispersed in a solvent. The effects of Brownian motion, anisotropic hydrodynamic drag, a steric force in the form of the Maier-Saupe potential, and, most importantly, a mean-field magnetic potential are included in the model. The development is similar to previous models for liquid-crystalline polymers. The model predicts multiple orientational states for the dispersion, and this phase behavior is described in terms of an orientational order parameter S and an average alignment parameter J; the latter is introduced because the magnetic particles have distinguishable direction due to polarity. A transition from isotropic to nematic phases at equilibrium is predicted. Multiple nematic phases-both prolate and oblate-are predicted in the presence of steady shear flow and external magnetic field parallel to the flow. The effect of increasing magnetic interparticle interactions and particle concentration is also presented. Comparisons with experimental data for the steady shear viscosity show very good agreement. PMID:16256493

  10. Evaluación del desempeño de modelos de dispersión de contaminantes aplicados a cañones urbanos Evaluation of the performance of atmospheric dispersion models applied to urban street canyons

    Directory of Open Access Journals (Sweden)

    Laura E. Venegas

    2012-06-01

    Full Text Available En los cañones urbanos, frecuentemente, se presentan concentraciones de contaminantes en aire varias veces superiores a la contaminación de fondo urbana. En este trabajo, se comparan valores de concentraciones de monóxido de carbono (CO en aire medidas dentro de un cañón urbano con las estimadas mediante algunos modelos de dispersión atmosférica aplicables a procesos que se verifican en los cañones: STREET, STREET-BOX, OSPM y AEOLIUS. Se presenta la evaluación para condiciones de sotavento, barlovento y para direcciones intermedias del viento. En la comparación, se utilizaron los valores horarios de concentraciones de CO en aire medidas durante un año en el interior de un cañón urbano de Göttinger Strässe (Hannover, Alemania y en el techo de un edificio lindero, de velocidad y dirección del viento observadas en el techo del mismo edificio y de flujo de tránsito vehicular en la calle del cañón. Los resultados generados por el modelo STREET con una constante empírica k=7, subestimaron las concentraciones observadas, obteniéndose un mejor desempeño con k= 12,1. El modelo STREET-BOX es adecuado para condiciones de sotavento y direcciones intermedias, pero presenta diferencias importantes con las concentraciones observadas a barlovento. En general, los resultados aportados por los modelos OSPM y AEOLIUS fueron los que menos se apartaron de los valores observados.Air pollutant concentrations inside street canyons are usually several times background concentrations in urban areas. In this paper, carbon monoxide (CO concentrations observed in a street canyon are compared with estimated values obtained using four atmospheric dispersion models: STREET, STREET-BOX, OSPM and AEOLIUS. Results for leeward, windward and intermediate wind directions are analyzed. Data used in the model evaluation include one year of hourly CO concentrations measured inside a street canyon of Göttinger Strässe (Hannover, Germany and at the roof of a

  11. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Smith Korsholm, U.; Havskov Soerensen, J. (Danish Meteorological Institute (DMI), Copenhagen (Denmark)); Astrup, P.; Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy. Radiation Research Div., Roskilde (Denmark))

    2011-04-15

    The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)

  12. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    International Nuclear Information System (INIS)

    The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)

  13. Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism%Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism

    Institute of Scientific and Technical Information of China (English)

    陶如意; 王浩; 黄蓓

    2011-01-01

    For the aerial dispersing interior ballistic process and submunition exterior ballistic initial conditions of cluster munition with piston maximum travel limit, a novel model is established, and the numerical simulation is performed. The piston maximum travel limit and the effect of reaction force on carrier body are researched using the internal ballistic model. Guide tube, cluster munition rotating and submunition assembly are analyzed using the submunition initial external ballistic model. The computational results are consistent with the practical process and the experimental data, and prove the rationality of this model. The theoretical methods are presented for the construction design and dispersion analysis of piston dispersal mechanism.

  14. Dispersive infrared spectroscopy measurements of atmospheric CO₂ using a Fabry-Pérot interferometer sensor.

    Science.gov (United States)

    Chan, K L; Ning, Z; Westerdahl, D; Wong, K C; Sun, Y W; Hartl, A; Wenig, M O

    2014-02-15

    In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO2) using a new scanning Fabry-Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3,900 nm to 5,220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO2 absorption band (~4,280 nm) and sampling resolution of 20 nm. The CO2 concentration is determined from the measured optical absorption spectra by fitting it to the CO2 reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H2O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO2 measurement for 1 minute averaged data is about ±2.5 ppmv, and down to ± 0.8ppmv for 10 minute averaged data. A field test of atmospheric CO2 measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO2 analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO2 measurement featuring high accuracy, correction of non-linear absorption and interference of water vapor. PMID:24291130

  15. Automated source term and wind parameter estimation for atmospheric transport and dispersion applications

    Science.gov (United States)

    Bieringer, Paul E.; Rodriguez, Luna M.; Vandenberghe, Francois; Hurst, Jonathan G.; Bieberbach, George; Sykes, Ian; Hannan, John R.; Zaragoza, Jake; Fry, Richard N.

    2015-12-01

    Accurate simulations of the atmospheric transport and dispersion (AT&D) of hazardous airborne materials rely heavily on the source term parameters necessary to characterize the initial release and meteorological conditions that drive the downwind dispersion. In many cases the source parameters are not known and consequently based on rudimentary assumptions. This is particularly true of accidental releases and the intentional releases associated with terrorist incidents. When available, meteorological observations are often not representative of the conditions at the location of the release and the use of these non-representative meteorological conditions can result in significant errors in the hazard assessments downwind of the sensors, even when the other source parameters are accurately characterized. Here, we describe a computationally efficient methodology to characterize both the release source parameters and the low-level winds (eg. winds near the surface) required to produce a refined downwind hazard. This methodology, known as the Variational Iterative Refinement Source Term Estimation (STE) Algorithm (VIRSA), consists of a combination of modeling systems. These systems include a back-trajectory based source inversion method, a forward Gaussian puff dispersion model, a variational refinement algorithm that uses both a simple forward AT&D model that is a surrogate for the more complex Gaussian puff model and a formal adjoint of this surrogate model. The back-trajectory based method is used to calculate a "first guess" source estimate based on the available observations of the airborne contaminant plume and atmospheric conditions. The variational refinement algorithm is then used to iteratively refine the first guess STE parameters and meteorological variables. The algorithm has been evaluated across a wide range of scenarios of varying complexity. It has been shown to improve the source parameters for location by several hundred percent (normalized by the

  16. Can the confidence in long range atmospheric transport models be increased? The Pan-European experience of ENSEMBLE

    DEFF Research Database (Denmark)

    Galmarini, S.; Bianconi, R.; Klug, W.;

    2004-01-01

    Is atmospheric dispersion forecasting an important asset of the early-phase nuclear emergency response management? Is there a 'perfect atmospheric dispersion model'? Is there a way to make the results of dispersion models more reliable and trustworthy? While seeking to answer these questions the...

  17. GA-based dynamical correction of dispersion coefficients in Lagrangian puff model

    Institute of Scientific and Technical Information of China (English)

    马元巍; 王德忠; 吉志龙

    2015-01-01

    In atmospheric dispersion models of nuclear accident, the dispersion coefficients were usually obtained by tracer experiment, which are constant in different atmospheric stability classifications. In fact, the atmospheric wind field is complex and unstable. The dispersion coefficients change even in the same atmospheric stability, hence the great errors brought in. According to the regulation, the air concentration of nuclides around nuclear power plant should be monitored during an accident. The monitoring data can be used to correct dispersion coefficients dynamically. The error can be minimized by correcting the coefficients. This reverse problem is nonlinear and sensitive to initial value. The property of searching the optimal solution of Genetic Algorithm (GA) is suitable for complex high-dimensional situation. In this paper, coupling with Lagrange dispersion model, GA is used to estimate the coefficients. The simulation results show that GA scheme performs well when the error is big. When the correcting process is used in the experiment data, the GA-estimated results are numerical instable. The success rate of estimation is 5%lower than the one without correction. Taking into account the continuity of the dispersion coefficient, Savitzky-Golay filter is used to smooth the estimated parameters. The success rate of estimation increases to 75.86%. This method can improve the accuracy of atmospheric dispersion simulation.

  18. Analysis of a Kalman filter based method for on-line estimation of atmospheric dispersion parameters using radiation monitoring data

    DEFF Research Database (Denmark)

    Drews, Martin; Lauritzen, Bent; Madsen, Henrik

    2005-01-01

    A Kalman filter method is discussed for on-line estimation of radioactive release and atmospheric dispersion from a time series of off-site radiation monitoring data. The method is based on a state space approach, where a stochastic system equation describes the dynamics of the plume model...... parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter...... estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent...

  19. Dense-gas dispersion advection-diffusion model

    International Nuclear Information System (INIS)

    A dense-gas version of the ADPIC particle-in-cell, advection- diffusion model was developed to simulate the atmospheric dispersion of denser-than-air releases. In developing the model, it was assumed that the dense-gas effects could be described in terms of the vertically-averaged thermodynamic properties and the local height of the cloud. The dense-gas effects were treated as a perturbation to the ambient thermodynamic properties (density and temperature), ground level heat flux, turbulence level (diffusivity), and windfield (gravity flow) within the local region of the dense-gas cloud. These perturbations were calculated from conservation of energy and conservation of momentum principles along with the ideal gas law equation of state for a mixture of gases. ADPIC, which is generally run in conjunction with a mass-conserving wind flow model to provide the advection field, contains all the dense-gas modifications within it. This feature provides the versatility of coupling the new dense-gas ADPIC with alternative wind flow models. The new dense-gas ADPIC has been used to simulate the atmospheric dispersion of ground-level, colder-than-ambient, denser-than-air releases and has compared favorably with the results of field-scale experiments

  20. Atmospheric dispersion and deposition of iodine-131 released from the Hanford Site

    International Nuclear Information System (INIS)

    Approximately 2.6x104 TBq (700,000 curies) of iodine-131 were released to the air from reactor fuel processing plants on the Hanford Site in southcentral Washington State from December 1944 through December 1949. The Hanford Environmental Dose Reconstruction (HEDR) Project developed a suite of codes to estimate the doses that might have resulted from these releases. The Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) computer code is part of this suite. The RATCHET code implements a Lagrangian-trajectory, Gaussian-puff dispersion model that uses hourly meteorological and release rate data to estimate daily time-integrated air concentrations and surface contamination for use in dose estimates. In this model, iodine is treated as a mixture of three species (nominally, inorganic gases, organic gases, and particles). Model deposition parameters are functions of the mixture and meteorological conditions. A resistance model is used to calculate dry deposition velocities. Equilibrium between concentrations in the precipitation and the air near the ground is assumed in calculating wet deposition of gases, and irreversible washout of the particles is assumed. RATCHET explicitly treats the uncertainties in model parameters and meteorological conditions. Uncertainties in iodine-131 release rates and partitioning among the nominal species are treated by varying model input. The results of 100 model runs for December 1944 through December 1949 indicate that monthly average air concentrations and deposition have uncertainties ranging from a factor of two near the center of the time-integrated plume to more than an order of magnitude near the edge. These results indicate that -10% of the iodine-131 released to the atmosphere decayed during transit in the study area, -56% was deposited within the study area, and the remaining 34% was transported out of the study area while still in the air

  1. Characterization of the Atmospheric Dispersion Corrector of the Gemini Planet Imager

    CERN Document Server

    Hibon, Pascale; Dunn, Jennifer; Atwood, Jenny; Saddlemyer, Les; Sadakuni, Naru; Goodsell, Stephen; Macintosh, Bruce; Graham, James; Perrin, Marshall; Rantakyrö, Fredrik; Fesquet, Vincent; Serio, Andrew; Quiroz, Carlos; Cardwell, Andrew; Gausachs, Gaston; Savransky, Dmitry; Kerley, Dan; Hartung, Markus; Galvez, Ramon; Hardie, Kayla

    2014-01-01

    An Atmospheric Dispersion Corrector (ADC) uses a double-prism arrangement to nullify the vertical chromatic dispersion introduced by the atmosphere at non-zero zenith distances. The ADC installed in the Gemini Planet Imager (GPI) was first tested in August 2012 while the instrument was in the laboratory. GPI was installed at the Gemini South telescope in August 2013 and first light occurred later that year on November 11th. In this paper, we give an overview of the characterizations and performance of this ADC unit obtained in the laboratory and on sky, as well as the structure of its control software.

  2. Similitude and nonsymmetric geometry for dispersion modelling

    OpenAIRE

    Bonzon, N.; Brun, J.M.; Sinfort, C.; Mohammadi, B.

    2007-01-01

    A low complexity model for the transport of passive scalars is presented. It can be applied for environmental analysis, especially regarding the atmospheric drift of agricultural pesticides. A multi-level approach has been carried with a reduced dimension of the solution's space at each level. Similitude solutions are used in a non symmetric metric for the transport over long distances. The calculation does not require any PDE and is mesh free. The model also permits to access the solution in...

  3. Modeling pollutant dispersion within a tornadic thunderstorm

    International Nuclear Information System (INIS)

    A three-dimensional numerical model was developed to calculate ground-level air concentration and deposition of particles entrained in a tornadic thunderstorm. The rotational characteristics of the tornadic storm are within the larger mesoscale flow of the storm system and transported with the vortex. Turbulence exchange coefficients are based on empirical values. The quasi-Lagrangian method of moments is used to model the transport of concentration within a grid cell volume. Results indicate that updrafts and downdrafts, coupled with scavenging of particles by precipitation, account for most of the material being deposited closer to the site than anticipated. Approximately 5% of the pollutant is dispersed into the stratosphere

  4. A Landau fluid model for dispersive magnetohydrodynamics

    International Nuclear Information System (INIS)

    A monofluid model with Landau damping is presented for strongly magnetized electron-proton collisionless plasmas whose distribution functions are close to bi-Maxwellians. This description that includes dynamical equations for the gyrotropic components of the pressure and heat flux tensors, extends the Landau-fluid model of Snyder, Hammett, and Dorland [Phys. Plasmas 4, 3974 (1997)] by retaining Hall effect and finite Larmor radius corrections. It accurately reproduces the weakly nonlinear dynamics of dispersive Alfven waves whose wavelengths are large compared to the ion inertial length, whatever their direction of propagation, and also the rapid Landau dissipation of long magnetosonic waves in a warm plasma

  5. Iterative ensemble Kalman filter for atmospheric dispersion in nuclear accidents: An application to Kincaid tracer experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.L.; Su, G.F.; Chen, J.G. [Institute of Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Raskob, W. [Institute for Nuclear and Energy Technologies, Karlsruhe Institute of Technology, Karlsruhe, D-76021 (Germany); Yuan, H.Y., E-mail: hy-yuan@outlook.com [Institute of Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Huang, Q.Y. [Institute of Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2015-10-30

    Highlights: • We integrate the iterative EnKF method into the POLYPHEMUS platform. • We thoroughly evaluate the data assimilation system against the Kincaid dataset. • The data assimilation system substantially improves the model predictions. • More than 60% of the retrieved emissions are within a factor two of actual values. • The results reveal that the boundary layer height is the key influential factor. - Abstract: Information about atmospheric dispersion of radionuclides is vitally important for planning effective countermeasures during nuclear accidents. Results of dispersion models have high spatial and temporal resolutions, but they are not accurate enough due to the uncertain source term and the errors in meteorological data. Environmental measurements are more reliable, but they are scarce and unable to give forecasts. In this study, our newly proposed iterative ensemble Kalman filter (EnKF) data assimilation scheme is used to combine model results and environmental measurements. The system is thoroughly validated against the observations in the Kincaid tracer experiment. The initial first-guess emissions are assumed to be six magnitudes underestimated. The iterative EnKF system rapidly corrects the errors in the emission rate and wind data, thereby significantly improving the model results (>80% reduction of the normalized mean square error, r = 0.71). Sensitivity tests are conducted to investigate the influence of meteorological parameters. The results indicate that the system is sensitive to boundary layer height. When the heights from the numerical weather prediction model are used, only 62.5% of reconstructed emission rates are within a factor two of the actual emissions. This increases to 87.5% when the heights derived from the on-site observations are used.

  6. Iterative ensemble Kalman filter for atmospheric dispersion in nuclear accidents: An application to Kincaid tracer experiment

    International Nuclear Information System (INIS)

    Highlights: • We integrate the iterative EnKF method into the POLYPHEMUS platform. • We thoroughly evaluate the data assimilation system against the Kincaid dataset. • The data assimilation system substantially improves the model predictions. • More than 60% of the retrieved emissions are within a factor two of actual values. • The results reveal that the boundary layer height is the key influential factor. - Abstract: Information about atmospheric dispersion of radionuclides is vitally important for planning effective countermeasures during nuclear accidents. Results of dispersion models have high spatial and temporal resolutions, but they are not accurate enough due to the uncertain source term and the errors in meteorological data. Environmental measurements are more reliable, but they are scarce and unable to give forecasts. In this study, our newly proposed iterative ensemble Kalman filter (EnKF) data assimilation scheme is used to combine model results and environmental measurements. The system is thoroughly validated against the observations in the Kincaid tracer experiment. The initial first-guess emissions are assumed to be six magnitudes underestimated. The iterative EnKF system rapidly corrects the errors in the emission rate and wind data, thereby significantly improving the model results (>80% reduction of the normalized mean square error, r = 0.71). Sensitivity tests are conducted to investigate the influence of meteorological parameters. The results indicate that the system is sensitive to boundary layer height. When the heights from the numerical weather prediction model are used, only 62.5% of reconstructed emission rates are within a factor two of the actual emissions. This increases to 87.5% when the heights derived from the on-site observations are used

  7. Atmospheric dispersion study with 85Kr and SF6 gas

    International Nuclear Information System (INIS)

    85Kr concentration in air around the reprocessing plant was measured when it was released from the plant stack during the hot-test operation treating PWR spent fuels. A charcoal absorption method was devised for this experiment as a rapid, simple and inexpensive technique for the measurement of 85Kr concentration at about 10-9μCi/cm3. Special air samplers were located a few kilometers from the stack and the air was collected for an hour at a flow-rate of 1.5 liters per minute. About thirty air samples were taken and analyzed for 85Kr concentration successfully. The performance of the sampling and analytical methods employed was good, although some improvements were found to be necessary. An example is that an air-collection bag should be made of ''saran'' to minim+ze leakage. Usually sulfur hexafluoride gas is used as an air-tracer in an atmospheric diffusion study: analytical procedure for determining the gas concentration down to 10-3 ppb is well established. In this experiment SF6 gas was injected into the stack during the discharge of 85Kr and the concentration in sampled air was also determined. The results show a good correlation between 85Kr and SF6 concentration in sampled air. (author)

  8. Atmospheric Dispersion of Radioactivity from Nuclear Power Plant Accidents: Global Assessment and Case Study for the Eastern Mediterranean and Middle East

    OpenAIRE

    Theodoros Christoudias; Yiannis Proestos; Jos Lelieveld

    2014-01-01

    We estimate the contamination risks from the atmospheric dispersion of radionuclides released by severe nuclear power plant accidents using the ECHAM/Modular Earth Submodel System (MESSy) atmospheric chemistry (EMAC) atmospheric chemistry-general circulation model at high resolution (50 km). We present an overview of global risks and also a case study of nuclear power plants that are currently under construction, planned and proposed in the Eastern Mediterranean and Middle East, a region pron...

  9. Modeling of atmospheric pollutant transfers

    International Nuclear Information System (INIS)

    Modeling is today a common tool for the evaluation of the environmental impact of atmospheric pollution events, for the design of air monitoring networks or for the calculation of pollutant concentrations in the ambient air. It is even necessary for the a priori evaluation of the consequences of a pollution plume. A large choice of atmospheric transfer codes exist but no ideal tool is available which allows to model all kinds of situations. The present day approach consists in combining different types of modeling according to the requested results and simulations. The CEA has a solid experience in this domain and has developed independent tools for the impact and safety studies relative to industrial facilities and to the management of crisis situations. (J.S.)

  10. Mixing height derived from the DMI-HIRLAM NWP model, and used for ETEX dispersion modelling

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, J.H.; Rasmussen, A. [Danish Meteorological Inst., Copenhagen (Denmark)

    1997-10-01

    For atmospheric dispersion modelling it is of great significance to estimate the mixing height well. Mesoscale and long-range diffusion models using output from numerical weather prediction (NWP) models may well use NWP model profiles of wind, temperature and humidity in computation of the mixing height. This is dynamically consistent, and enables calculation of the mixing height for predicted states of the atmosphere. In autumn 1994, the European Tracer Experiment (ETEX) was carried out with the objective to validate atmospheric dispersion models. The Danish Meteorological Institute (DMI) participates in the model evaluations with the Danish Emergency Response Model of the Atmosphere (DERMA) using NWP model data from the DMI version of the High Resolution Limited Area Model (HIRLAM) as well as from the global model of the European Centre for Medium-Range Weather Forecast (ECMWF). In DERMA, calculation of mixing heights are performed based on a bulk Richardson number approach. Comparing with tracer gas measurements for the first ETEX experiment, a sensitivity study is performed for DERMA. Using DMI-HIRLAM data, the study shows that optimum values of the critical bulk Richardson number in the range 0.15-0.35 are adequate. These results are in agreement with recent mixing height verification studies against radiosonde data. The fairly large range of adequate critical values is a signature of the robustness of the method. Direct verification results against observed missing heights from operational radio-sondes released under the ETEX plume are presented. (au) 10 refs.

  11. Atmospheric Dispersal of Bioactive Streptomyces albidoflavus Strains Among Terrestrial and Marine Environments.

    Science.gov (United States)

    Sarmiento-Vizcaíno, Aida; Braña, Alfredo F; González, Verónica; Nava, Herminio; Molina, Axayacatl; Llera, Eva; Fiedler, Hans-Peter; Rico, José M; García-Flórez, Lucía; Acuña, José L; García, Luis A; Blanco, Gloria

    2016-02-01

    Members of the Streptomyces albidoflavus clade, identified by 16S rRNA sequencing and phylogenetic analyses, are widespread among predominant terrestrial lichens (Flavoparmelia caperata and Xanthoria parietina) and diverse intertidal and subtidal marine macroalgae, brown red and green (Phylum Heterokontophyta, Rhodophyta, and Chlorophyta) from the Cantabrian Cornice. In addition to these terrestrial and coastal temperate habitats, similar strains were also found to colonize deep-sea ecosystems and were isolated mainly from gorgonian and solitary corals and other invertebrates (Phylum Cnidaria, Annelida, Echinodermata, Arthropoda, and Porifera) living up to 4700-m depth and at a temperature of 2-4 °C in the submarine Avilés Canyon. Similar strains have been also repeatedly isolated from atmospheric precipitations (rain drops, snow, and hailstone) collected in the same area throughout a year observation time. These ubiquitous strains were found to be halotolerant, psychrotolerant, and barotolerant. Bioactive compounds with diverse antibiotic and cytotoxic activities produced by these strains were identified by high-performance liquid chromatography (HPLC) and database comparison. These include antibacterials (paulomycins A and B), antifungals (maltophilins), antifungals displaying also cytotoxic activities (antimycins and 6-epialteramides), and the antitumor compound fredericamycin. A hypothetical dispersion model is here proposed to explain the biogeographical distribution of S. albidoflavus strains in terrestrial, marine, and atmospheric environments. PMID:26224165

  12. Plutonium explosive dispersal modeling using the MACCS2 computer code

    International Nuclear Information System (INIS)

    The purpose of this paper is to derive the necessary parameters to be used to establish a defensible methodology to perform explosive dispersal modeling of respirable plutonium using Gaussian methods. A particular code, MACCS2, has been chosen for this modeling effort due to its application of sophisticated meteorological statistical sampling in accordance with the philosophy of Nuclear Regulatory Commission (NRC) Regulatory Guide 1.145, ''Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants''. A second advantage supporting the selection of the MACCS2 code for modeling purposes is that meteorological data sets are readily available at most Department of Energy (DOE) and NRC sites. This particular MACCS2 modeling effort focuses on the calculation of respirable doses and not ground deposition. Once the necessary parameters for the MACCS2 modeling are developed and presented, the model is benchmarked against empirical test data from the Double Tracks shot of project Roller Coaster (Shreve 1965) and applied to a hypothetical plutonium explosive dispersal scenario. Further modeling with the MACCS2 code is performed to determine a defensible method of treating the effects of building structure interaction on the respirable fraction distribution as a function of height. These results are related to the Clean Slate 2 and Clean Slate 3 bunkered shots of Project Roller Coaster. Lastly a method is presented to determine the peak 99.5% sector doses on an irregular site boundary in the manner specified in NRC Regulatory Guide 1.145 (1983). Parametric analyses are performed on the major analytic assumptions in the MACCS2 model to define the potential errors that are possible in using this methodology

  13. ATMOSPHERIC DISPERSION COEFFICIENTS AND RADIOLOGICAL AND TOXICOLOGICAL EXPOSURE METHODOLOGY FOR USE IN TANK FARMS

    Energy Technology Data Exchange (ETDEWEB)

    GRIGSBY KM

    2011-04-07

    This report presents the atmospheric dispersion coefficients used in Tank Farms safety analysis. The basis equations for calculating radiological and toxicological exposures are also included. In this revision, the time averaging for toxicological consequence evaluations is clarified based on a review of DOE complex guidance and a review of tank farm chemicals.

  14. Atmospheric Dispersion Coefficients and Radiological and Toxicological Exposure Methodology for Use in Tank Farms

    International Nuclear Information System (INIS)

    This report presents the atmospheric dispersion coefficients used for Tank Farms safety analyses. The development of the coefficients is also presented. The report contains the necessary documentation for meeting Software QA requirements for the GXQ software. The basic equations for calculating radiological doses and chemical exposures are included

  15. Sensitivity of numerical dispersion modeling to explosive source parameters

    International Nuclear Information System (INIS)

    The calculation of downwind concentrations from non-traditional sources, such as explosions, provides unique challenges to dispersion models. The US Department of Energy has assigned the Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) the task of estimating the impact of accidental radiological releases to the atmosphere anywhere in the world. Our experience includes responses to over 25 incidents in the past 16 years, and about 150 exercises a year. Examples of responses to explosive accidents include the 1980 Titan 2 missile fuel explosion near Damascus, Arkansas and the hydrogen gas explosion in the 1986 Chernobyl nuclear power plant accident. Based on judgment and experience, we frequently estimate the source geometry and the amount of toxic material aerosolized as well as its particle size distribution. To expedite our real-time response, we developed some automated algorithms and default assumptions about several potential sources. It is useful to know how well these algorithms perform against real-world measurements and how sensitive our dispersion model is to the potential range of input values. In this paper we present the algorithms we use to simulate explosive events, compare these methods with limited field data measurements, and analyze their sensitivity to input parameters. 14 refs., 7 figs., 2 tabs

  16. Characterization of exoplanet atmospheres using high-dispersion spectroscopy with the E-ELT and beyond

    Directory of Open Access Journals (Sweden)

    Snellen Ignas

    2013-04-01

    Full Text Available Ground-based high-dispersion (R ∼ 100,000 spectroscopy provides unique information on exoplanet atmospheres, inaccessible from space - even using the JWST or other future space telescopes. Recent successes in transmission- and dayside spectroscopy using CRIRES on the Very Large Telescope prelude the enormous discovery potential of high-dispersion spectrographs on the E-ELT, such as METIS in the thermal infrared, and HIRES in the optical/near-infrared. This includes the orbital inclination and masses of hundred(s of non-transiting planets, line-by-line molecular band spectra, planet rotation and global wind patterns, longitudinal spectral variations, and possibly isotopologue ratios. Thinking beyond the E-ELT, we advocate that ultimately a systematic search for oxygen in atmospheres of nearby Earth-like planets can be conducted using large arrays of relatively low-cost flux collector telescopes equipped with high-dispersion spectrographs.

  17. Model for Simulation Atmospheric Turbulence

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik

    1976-01-01

    A method that produces realistic simulations of atmospheric turbulence is developed and analyzed. The procedure makes use of a generalized spectral analysis, often called a proper orthogonal decomposition or the Karhunen-Loève expansion. A set of criteria, emphasizing a realistic appearance, a...... eigenfunctions and estimates of the distributions of the corresponding expansion coefficients. The simulation method utilizes the eigenfunction expansion procedure to produce preliminary time histories of the three velocity components simultaneously. As a final step, a spectral shaping procedure is then applied....... The method is unique in modeling the three velocity components simultaneously, and it is found that important cross-statistical features are reasonably well-behaved. It is concluded that the model provides a practical, operational simulator of atmospheric turbulence....

  18. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part II: verification of the source term and analysis of regional-scale atmospheric dispersion

    International Nuclear Information System (INIS)

    Regional-scale atmospheric dispersion simulations were carried out to verify the source term of 131I and 137Cs estimated in our previous studies, and to analyze the atmospheric dispersion and surface deposition during the Fukushima Dai-ichi Nuclear Power Plant accident. The accuracy of the source term was evaluated by comparing the simulation results with measurements of daily and monthly surface depositions (fallout) over land in eastern Japan from March 12 to April 30, 2011. The source term was refined using observed air concentrations of radionuclides for periods when there were significant discrepancies between the calculated and measured daily surface deposition, and when environmental monitoring data, which had not been used in our previous studies, were now available. The daily surface deposition using the refined source term was predicted mostly to within a factor of 10, and without any apparent bias. Considering the errors in the model prediction, the estimated source term is reasonably accurate during the period when the plume flowed over land in Japan. The analysis of regional-scale atmospheric dispersion and deposition suggests that the present distribution of a large amount of 137Cs deposition in eastern Japan was produced primarily by four events that occurred on March 12, 15–16, 20, and 21–23. The ratio of wet deposition to the total varied widely depending on the influence by the particular event. - Highlights: ► Source term during the Fukushima Dai-ichi Nuclear Power Plant accident was verified. ► Accuracy of surface deposition by atmospheric dispersion simulations was evaluated. ► The source term of 131I and 137Cs was refined to explain the deposition measurements. ► The source term was reasonably accurate while plumes flowed over land in Japan. ► Primary 137Cs deposition over land occurred on March 12, 15–16, 20, and 21–23.

  19. Modelling the dispersion and scavenging of plutonium in marine systems

    International Nuclear Information System (INIS)

    An Oceanic General Circulation Model (OGCM) has been developed for modelling the dispersion of plutonium (Pu) and other non-conservative tracers in the marine system. A plutonium scavenging model as well as an advection-diffusion model has been incorporated into the OGCM. It appears that the best way to validate a numerical model for the dispersion of non-conservative tracers in the global ocean would be to calculate radionuclide concentrations in the ocean from atmospheric nuclear tests (global and local fallout) and to compare them with observations. This paper concentrates on predictions of the distributions and vertical profiles of 239,240Pu in the water column of the Pacific Ocean, both from global fallout as well as from local fallout from nuclear weapons tests at Bikini and Enewetak Atolls. The water profile concentrations, water and sediment inventories of 239,240Pu have shown generally good agreement between calculated and observed data. Nevertheless, the present model cannot calculate the water profiles in the north North Pacific or the west coast of the American continent very well, mainly because of the underestimation of the effect of biological productivity on Pu scavenging and its removal from the water column in these regions. (author)

  20. MET-RODOS: A comprehensive atmospheric dispersion module

    DEFF Research Database (Denmark)

    Mikkelsen, T.; Thykier-Nielsen, S.; Astrup, P.; Santabárbara, J.M.; Sørensen, J.H.; Rasmussen, A.; Robertson, L.; Ullerstig, A.; Deme, S.; Martens, R.; Bartzis, J.G.; Päsler-Sauer, J.

    the system via on-line connections to on-site local meteorological observations (met-towers and sodars) and via network (either public domain Internet or user-owned point-to-point ISDN) connections to remote national or international meteorological forecasting services. In its final form, scheduled...... for operational use in 1999, the: MET-RODOS meteorological module is intended to service the PODOS system with actual and forecast (+36 h) nuclei-specific air concentrations, deposition values, and gamma radiation estimates on the local, national, and European scale. Provisions are furthermore being...... made for accommodating on line available radiological monitoring data in the meteorological model chains in order for the module to assist with source term determination based on real-time data assimilation and back-fitting procedures....

  1. Coordination of atmospheric dispersion activities for the real-time decision support system RODOS

    International Nuclear Information System (INIS)

    This projects task has been to coordinate activities among the RODOS Atmospheric Dispersion sub-group A participants, with the overall objective of developing and integrating an atmospheric transport and dispersion module for the joint European Real-time On-line DecisiOn Support system RODOS headed by FZK (formerly KfK), Germany. The project's final goal is the establishment of a fully operational, system-integrated atmospheric transport module for the RODOS system by year 2000, capable of consistent now- and forecasting of radioactive airborne spread over all types of terrain and on all scales of interest, including in particular complex terrain and the different scales of operation, such as the local, the national and the European scale. (au)

  2. Longitudinal dispersion modeling in small streams

    Science.gov (United States)

    Pekarova, Pavla; Pekar, Jan; Miklanek, Pavol

    2014-05-01

    The environmental problems caused by the increasing of pollutant loads discharged into natural water bodies are very complex. For that reason the cognition of transport mechanism and mixing characteristics in natural streams is very important. The mathematical and numerical models have become very useful tools for solving the water management problems. The mathematical simulations based on numerical models of pollution mixing in streams can be used (for example) for prediction of spreading of accidental contaminant waves in rivers. The paper deals with the estimation of the longitudinal dispersion coefficients and with the numerical simulation of transport and transformation of accidental pollution in the small natural streams. There are different ways of solving problems of pollution spreading in open channels, in natural rivers. One of them is the hydrodynamic approach, which endeavours to understand and quantify the spreading phenomenon in a stream. The hydrodynamic models are based on advection-diffusion equation and the majority of them are one-dimensional models. Their disadvantage is inability to simulate the spread of pollution until complete dispersion of pollutant across the stream section is finished. Two-dimensional mixing models do not suffer from these limitations. On the other hand, the one-dimensional models are simpler than two-dimensional ones, they need not so much input data and they are often swifter. Three-dimensional models under conditions of natural streams are applicable with difficulties (or inapplicable) for their complexity and demands on accuracy and amount of input data. As there was mentioned above the two-dimensional models can be used also until complete dispersion of pollutant across the stream section is not finished, so we decided to apply the two-dimensional model SIRENIE. Experimental microbasin Rybarik is the part of the experimental Mostenik brook basin of IH SAS Bratislava. It was established as a Field Hydrological

  3. Verification of the dispersion model by airborne carbon 14C

    International Nuclear Information System (INIS)

    This paper provides insight in the verification of the Lagrangean dispersion model for dose calculation in the environment. The verification method was based on the measurement of the airborne carbon 14C concentration which can be slightly increased close to the nuclear power plant. The results proved that this method is sensitive enough and that the sensitivity analysis can be used for model verification or for identification of possible improvements of the used meteorological data. The Lagrangean model is used at Krsko nuclear power plant (NPP) for calculation of dispersion coefficients and dose in the environment. To show compliance with the authorized dose limits it is required to present a realistic calculation of the dose to the public. This is a numerical model designed to calculate air pollution dispersion in the area of 25km x 25km. The model uses on-line local meteorological measurements. The same model was already verified for another location around a coal- fired power plant based on emission and environmental measurements of SO2. Krsko NPP is placed near the Sava River in a semiopened basin surrounded by several hills. The region is characterized by low winds and frequent thermal inversions. This paper presents a verification of the short range dispersion model based on the fact that the airborne carbon 14C concentration can be slightly increased close to the nuclear power plant. Other radioactive effluents are not detectable in the environment and carbon 14C measurements are accurate enough to detect small deviations from natural 14C levels and to compare them with the calculated concentration based on 14C effluents. The most of airborne 14C is released during the refuelling outage. Within the pre-selected period of ten days, increased effluents of 14C in the form of CO2 were sampled from the plant ventilation. The average atmospheric dispersion parameters were calculated for two locations in the environment where CO2 sampling plates were installed

  4. Regulatory dispersion modelling of traffic-originated pollution

    International Nuclear Information System (INIS)

    This thesis describes the national finite line source model (CAR-FMI) for the dispersion of traffic-originated pollution from an open road network. CAR- FMI computes the concentrations of carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO2), total of nitrogen oxides (NOx), ozone (O3) and exhaust fine particulate matter (PM2.5) in local scale using the Gaussian plume dispersion with dry deposition associated with PM2.5. The computed results of statistically analysed hourly concentrations are available in tabular form or presented graphically utilizing the GIS (Geographic Information System) MapInfo. The modelled NOx concentrations are compared with the field measurements as well as with the computed results of a Lagrangian model (GRAL). The comparisons show a good agreement between modelled and measured concentrations except in case of weak wind speed conditions when CAR-FMI substantially overestimates the concentrations. The overestimation was the result of the meandering effect, which is not taken into account in the first version of the model. A numerical method for the correction of the influence by meandering is suggested in this work. A semi-empirical method for the estimation of yearly PM10 concentration is presented. Also a statistical method for the estimation of the long-range transported PM2.5 concentration is described. Additionally, an indirect statistical method for the estimation of the emission factor of non-exhaust fine particles by the traffic in summertime conditions is suggested in this thesis. All original papers are associated with the different projects of the Atmospheric dispersion modelling group in Air Quality Research (AQR) of the Finnish Meteorological Institute (FMI). (orig.)

  5. Novel applications of the dispersive optical model

    CERN Document Server

    Dickhoff, W H; Mahzoon, M H

    2016-01-01

    A review of recent developments of the dispersive optical model (DOM) is presented. Starting from the original work of Mahaux and Sartor, several necessary steps are developed and illustrated which increase the scope of the DOM allowing its interpretation as generating an experimentally constrained functional form of the nucleon self-energy. The method could therefore be renamed as the dispersive self-energy method. The aforementioned steps include the introduction of simultaneous fits of data for chains of isotopes or isotones allowing a data-driven extrapolation for the prediction of scattering cross sections and level properties in the direction of the respective drip lines. In addition, the energy domain for data was enlarged to include results up to 200 MeV where available. An important application of this work was implemented by employing these DOM potentials to the analysis of the (\\textit{d,p}) transfer reaction using the adiabatic distorted wave approximation (ADWA). We review the fully non-local DOM...

  6. NARAC: An Emergency Response Resource for Predicting the Atmospheric Dispersion and Assessing the Consequences of Airborne Radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, M M

    2005-08-23

    Hazardous radioactive materials can be released into the atmosphere by accidents at nuclear power plants, fuel processing facilities, and other facilities, and by transportation accidents involving nuclear materials. In addition, the post-cold-war proliferation of nuclear material has increased the potential for terrorism scenarios involving radiological dispersal devices, improvised nuclear devices, and inadequately secured military nuclear weapons. To mitigate these risks, the National Atmospheric Release Advisory Center (NARAC) serves as a national resource for the United States, providing tools and services to quickly predict the environmental contamination and health effects caused by airborne radionuclides, and to provide scientifically based guidance to emergency managers for the protection of human life. NARAC's expert staff uses computer models, supporting databases, software systems, and communications systems to predict the plume paths and consequences of radiological, chemical, and biological atmospheric releases.

  7. The MRBT model: an analytical dispersion model in a finite mixing layer. Sensitivity analysis and validation against tracer measurements

    Science.gov (United States)

    Andretta, Massimo; Bianconi, Roberto; Flospergher, Walter; Tamponi, Matteo

    This paper describes the characteristics of the MRBT model for studying the dispersion of a pollutant in the lower atmosphere under conditions of spatial homogeneity. The MRBT is shown to be a simple and efficient model based upon a non-stationary analytical solution of the atmospheric dispersion equation in a finite mixing layer. The results of the sensitivity analysis and of validation testing, made with field measurements of tracers carried out at the Nuclear Research Centre in Karlsruhe (Germany), demonstrate the superiority of MRBT with respect to traditional Gaussian models. The model is currently implemented in FORTRAN 77 for the personal computer and is suitable for an initial assessment of short-term atmospheric dispersion with limited computing resources.

  8. Analytical Dispersion Formula for a Point Source by Using Spherical Coordinate on Gaussian Plume Model

    International Nuclear Information System (INIS)

    The objective of this work is provide analytical formula of the dispersion parameters to describe the polluted point source in space release to the atmosphere. The Gaussian Plume Model (GPM) choice as appropriates framework to illustrate this work. The analytical formula of the Gaussian Plume Model dispersion parameters in spherical coordinate was written. These parameters were calculated at different azimuth and polar angle and with different stability index and plotted in family of curves. This curves show a symmetrical distribution of the vertical and horizontal dispersion parameters around the polar angleπ /2

  9. Lagrangian modeling of atmospheric dispersion of radionuclides and geographical information systems as tools to support emergency planning in area of influence of nuclear complex of Angra dos Reis, RJ, Brazil; Modelagem Lagrangeana da dispersao atmoferica de radionuclideos e sistemas de informacao geografica como ferramentas de suporte ao planejamento de emergencia na area de influencia do complexo nuclear de Angra dos Reis, RJ

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Corbiniano

    2013-07-01

    Industrial accidents generally endanger structures and the set of environmental influence area where the enterprises are located, especially when affected by atmospheric dispersion of their pollutants, whose concern with the evacuation of the population is the main goal in emergency situations. Considering the nuclear complex Angra dos Reis - RJ, based on computer modeling analysis of the mechanisms of pollutant dispersion in conjunction with geographic information systems were developed. Thus, information about the dispersion of radionuclides - from simulations performed on the HYSPLIT; meteorological data (direction, intensity and calm on the wind regime and analysis of the wind field in the region using WRF), occurrence of landslides and data on the environmental study area were integrated into a GIS database using ArcGIS platform. Aiming at the identification and definition of escape routes in case of evacuation from accidental events in CNAAA, the results point solutions for long-term planning, based on weather and landslides, and short-term, supported by simulations of the dispersion radionuclides, in order to support actions that assist local emergency planning. (author)

  10. Assessment of radiological impact due to a hypothetical core disruptive accident for PFBR using an advanced atmospheric dispersion system

    International Nuclear Information System (INIS)

    Radiological impact due to air borne effluent dispersion from a hypothetical Core Disruptive Accident (CDA) scenario for Prototype Fast Breeder Reactor (PFBR) at Kalpakkam coastal site is estimated using an advanced system consisting of a 3-d meso-scale atmospheric model and a random walk particle dispersion model. A simulation of dispersion for CDA carried out for a typical summer day on 24th May 2003 predicted development of land-sea breeze circulation and Thermal Internal Boundary Layer (TIBL) at Kalpakkam site, which have been confirmed by observations. Analysis of dose distribution corresponding to predicted atmospheric conditions shows maximum dose from stack releases beyond the site boundary at about 4 km during TIBL fumigation and stable conditions respectively. A multi mode spatial concentration distribution has been noticed with diurnal meandering of wind under land sea breeze circulation. Over a meso-scale range of 25 km, turning of plume under sea breeze and maximum concentration along plume centerline at distances of 3 to 10 km have been noticed. The study has enabled to simulate the more complex meteorological situation that is actually present at the site. (author)

  11. Atmospheric dispersion analysis in preparing permit applications for the new nuclear power plants in the United States

    International Nuclear Information System (INIS)

    Nuclear power generation has become an increasingly attractive alternative in the United States (U.S.) power market due to several factors: growing demand for electric power, increasing global competition for fossil fuels, concern over greenhouse gas emissions and their potential impact on global warming, and the desire for energy independence. Currently there are more than 19 utilities and nuclear energy groups in the U.S. have announced plans for new plants to submit permit applications of Early Site Permits (ESP) and/or Combined Licenses (COL). In support of the permit applications, the following assessments are required: potential dispersion of radioactive material from, and the radioactive consequences of, design-basis accidents to aid in evaluating the acceptability of a site and the adequacy of engineered safety features for a nuclear power plants; maximum potential annual radiation dose to the public resulting from the routine release of radioactive materials in gaseous effluent; habitability of the control room during postulated design-basis radiological accidents and hazardous chemical releases; near-real-time atmospheric transport and diffusion estimates immediately following an accidental releases of airborne radioactive material to provide input to the evaluation of the consequences of radiological releases to the atmosphere and to aid in the implementation of emergency response decisions; the potential dispersion of radioactive materials from, and the radiological consequences of, a spectrum of accidents to aid in evaluating the environmental risk posed by a nuclear power plant; and the non-radiological related environmental effects, such as fogging, icing, and salt drift from cooling towers or ponds, to aid in evaluating the environmental impact of a nuclear power plant. The paper presents an overview of dispersion modeling approaches/techniques. Common regulatory conformance issues, particularly regarding (1) available computer modeling tools

  12. Prime focus wide-field corrector designs with lossless atmospheric dispersion correction

    CERN Document Server

    Saunders, Will; Smith, Greg; Kent, Steve; Doel, Peter

    2014-01-01

    Wide-Field Corrector designs are presented for the Blanco and Mayall telescopes, the CFHT and the AAT. The designs are Terezibh-style, with 5 or 6 lenses, and modest negative optical power. They have 2.2-3 degree fields of view, with curved and telecentric focal surfaces suitable for fiber spectroscopy. Some variants also allow wide-field imaging, by changing the last WFC element. Apart from the adaptation of the Terebizh design for spectroscopy, the key feature is a new concept for a 'Compensating Lateral Atmospheric Dispersion Corrector', with two of the lenses being movable laterally by small amounts. This provides excellent atmospheric dispersion correction, without any additional surfaces or absorption. A novel and simple mechanism for providing the required lens motions is proposed, which requires just 3 linear actuators for each of the two moving lenses.

  13. Prime focus wide-field corrector designs with lossless atmospheric dispersion correction

    Energy Technology Data Exchange (ETDEWEB)

    Saunders, Will [Australian Astron. Observ.; Gillingham, Peter [Australian Astron. Observ.; Smith, Greg [Australian Astron. Observ.; Kent, Steve [Fermilab; Doel, Peter [University Coll. London

    2014-07-18

    Wide-Field Corrector designs are presented for the Blanco and Mayall telescopes, the CFHT and the AAT. The designs are Terezibh-style, with 5 or 6 lenses, and modest negative optical power. They have 2.2-3 degree fields of view, with curved and telecentric focal surfaces suitable for fiber spectroscopy. Some variants also allow wide-field imaging, by changing the last WFC element. Apart from the adaptation of the Terebizh design for spectroscopy, the key feature is a new concept for a 'Compensating Lateral Atmospheric Dispersion Corrector', with two of the lenses being movable laterally by small amounts. This provides excellent atmospheric dispersion correction, without any additional surfaces or absorption. A novel and simple mechanism for providing the required lens motions is proposed, which requires just 3 linear actuators for each of the two moving lenses.

  14. Field Studies for Validation of Urban Dispersion Models - Current Status and Research Needs

    Science.gov (United States)

    Allwine, J.

    2007-12-01

    Urban dispersion models are important tools in addressing consequences from potential releases of harmful airborne materials in urban areas. These models are used by emergency management, law enforcement, and intelligence personnel to effectively plan for and respond to potential terrorist attacks and accidents. Field studies are vitally important for improving and validating these urban dispersion models which are used to simulate contaminant dispersion in and around cities. Over the past decade, three major urban field studies have been designed and conducted in the United States. The primary objectives of these studies have been to advance the state-of-science of understanding and modeling atmospheric flows and dispersion in and around cities, and to provide field observation for validation of urban dispersion models. The three major field studies (Salt Lake City, October 2000; Oklahoma City, July 2003; and New York City, August 2005) were conducted in cities of different sizes, in different geographic regions and during different times of the year. The tracer and meteorological data from these three field campaigns provide a rich dataset for validation of urban dispersion models over a range of conditions. The status and uses of the three urban dispersion datasets will be summarized, followed by a discussion of the current observational gaps and research needs in characterizing specific urban dispersion processes, such as outdoor-indoor coupling and outdoor-subway coupling.

  15. A tracer investigation of the atmospheric dispersion in the Dyrnaes Valley, Greenland

    International Nuclear Information System (INIS)

    Mining at Kvanefjeld, Greenland, will result in releases of air pollution gases. In order to measure the dilution of these gases tracer experiments were carried out in July-August 1981. Results from these experiments are described. The Kvanefjeld constitutes the northwestern side of a valley. The tracer was released at the Kvanefjeld during the night and sampled in the valley. The measured tracer concentrations were compared with those calculated by use of a conventional model of the dispersion of plumes. The dilution of the tracer was found to correspond to the dilution at ground level of a plume from a stack of 100-200 m height in atmospheric neutral conditions (wind speed 5 m/s). General aspects of the flow-field in the valley are discussed. It was observed that the flow direction in the valley shifts between downvalley and upvalley with a period of approximately 1 hour. It is suggested that this behaviour is caused by the interplay of a drainage flow and a sea-breeze. (author)

  16. Uncertainty analyses for the atmospheric dispersion submodule of UFOMOD with emphasis on parameter correlations

    International Nuclear Information System (INIS)

    Special emphasis is put on some helpful theoretical investigations concerning: 1. different types of correlation between uncertain model parameters; 2. test procedures to find out the most sensitive uncertain model parameters; 3. the percentage contribution of parameter variations to changes in consequence values. For the mentioned submodule of the new program system UFOMOD version NE 87/1, the most important parameters are stable in their rankings regardless of the underlying distributions (predefined by experts or all uniformly distributed, respectively). For the less important parameters the values of the sensitivity measures (PRCC values) vary for predefined or uniform distributions, respectively. But even then in most cases the ranking is the same. Increasing sample sizes (n = 80, 100) lead to more precision in sensitivity calculations, i.e. lead to a decrease of the critical 'white noise level' (garbage level) of absolute PRCC values. R2-values (coefficients of determination) in conjunction with the corresponding PRCC values visualize the percentage contribution of each uncertain model parameter (or groups of uncertain parameters) to uncertainty in consequences. This is important, because a large absolute PRCC value is not in every case an indication for a considerable amount of responsibility for uncertainty in consequences. The restriction to pure model parameters and revised parameter variations in the atmospheric dispersion and deposition submodule of the new UFOMOD code system lead to significantly smaller uncertainty bands than for the old UFOMOD/B3 code. Variations in deposition velocities and the mixing height parameters play the most important role for uncertainties in the activity concentration values. (orig./HP)

  17. Comparison of the atmospheric dispersion calculation with the measurement of γ-radiation levels from Ar-41 releases

    International Nuclear Information System (INIS)

    The purpose of the study was to check the accuracy of a simple gaussian atmospheric diffusion model for a complex terrain condition in Germany. In the frame of the existing surveillance system, the annual γ doses due to 41Ar emission from a research reactor have been measured in the environment, mainly with sensitive G-M detectors. The computer code AIREM was used to calculate the atmospheric dispersion. This code is based on a simple sector averaged gaussian diffusion equation for long-term average calculation. For the calculation of cloud-dose rates, the finite extent model (Computer Code EGAD) was used. The results showed that at fairly flat locations the ratios of calculated to measured doses vary between 1.8 to 3.4 Measurements were mainly made with sensitive G-M detectors. (U.K.)

  18. Optimization of wind speed on dispersion of pollutants using coupled receptor and dispersion model

    Indian Academy of Sciences (India)

    N Anu; S Rangabhashiyam; Rahul Antony; N Selvaraju

    2015-08-01

    Air pollutants emission from various source categories can be quantified through mass balance (receptor model) techniques, multivariate data analysis and dispersion model. The composition of particulate matter from various emission points (emission inventory) and the massive analysis of the composition in the collected samples from various locations (receptor) are used to estimate quantitative source contribution through receptor models. In dispersion model, on the other hand the emission rates (g/m3) from various sources together with particle size, stack height, topography, meteorological conditions (temperature, humidity, wind speed and directions, etc.) will affect the pollutant concentration at a point or in a region. The parameters used in dispersion model are not considering in receptor models but have been affecting indirectly as difference concentration at various receptor locations. These differences are attributed and possible erroneous results can be viewed through coupled receptor-dispersion model analysis. The current research work proposed a coupled receptor-dispersion model to reduce the difference between predicted concentrations through optimized wind velocity used in dispersion model. The converged wind velocities for various error percentages (10%, 40%, 60% and 80%) in receptor concentration have been obtained with corresponding increase in the error. The proposed combined approaches help to reconcile the differences arise when the two models used in an individual mode.

  19. Development of a code to simulate dispersion of atmospheric released tritium gas in the environmental media and to evaluate doses. TRIDOSE

    International Nuclear Information System (INIS)

    A computer code (TRIDOSE) was developed to assess the environmental impact of atmospheric released tritium gas (T2) from nuclear fusion related facilities. The TRIDOSE simulates dispersion of T2 and resultant HTO in the atmosphere, land, plant, water and foods in the environment, and evaluates contamination concentrations in the media and exposure doses. A part of the mathematical models in TRIDOSE were verified by comparison of the calculation with the results of the short range (400 m) dispersion experiment of HT gas performed in Canada postulating a short-time (30 minutes) accidental release. (author)

  20. Development of a code to simulate dispersion of atmospheric released tritium gas in the environmental media and to evaluate doses. TRIDOSE

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Mikio [Nuclear Engineering Co., Ltd., Hitachi, Ibaraki (Japan); Noguchi, Hiroshi; Yokoyama, Sumi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-11-01

    A computer code (TRIDOSE) was developed to assess the environmental impact of atmospheric released tritium gas (T{sub 2}) from nuclear fusion related facilities. The TRIDOSE simulates dispersion of T{sub 2} and resultant HTO in the atmosphere, land, plant, water and foods in the environment, and evaluates contamination concentrations in the media and exposure doses. A part of the mathematical models in TRIDOSE were verified by comparison of the calculation with the results of the short range (400 m) dispersion experiment of HT gas performed in Canada postulating a short-time (30 minutes) accidental release. (author)

  1. CFD analysis of atmospheric dispersion in a large terrain of Kakrapar atomic power station in presence of structural buildings

    International Nuclear Information System (INIS)

    The work presents a computational fluid dynamics (CFD) calculation to investigate the dispersion of SF6 over terrain of Kakrapar nuclear power plant using the actual meteorological data. Three-dimensional, transient simulations have been carried out using CFD code PHOENICS. The CFD calculation covers a domain of 3.2 km X 3.2 km in plan and 0.5 km in height. Atmospheric dispersion in presence of the structures like Reactor Building, Natural Draft Cooling Tower and Turbine Building has been studied. The SF6 was released from the stack at a height of 100 m. SF6 released was considered for 2 hours duration at a rate of 1 gm/sec. This model was used to simulate the transport of SF6 for 6 hours. The ground level concentration of SF6 was monitored

  2. Numerical simulation of atmospheric dispersion and high radiological dose zone due to accidental releases from Fukushima Power Plant

    International Nuclear Information System (INIS)

    Atmospheric dispersion calculations are made for the accidental releases of radionuclides from Fukushima Dai-ichi Nuclear Power Plant (FDNPP) using a weather model coupled Lagrangian particle dispersion model FLEXPART-WRF in a 30 km range to understand the formation of high radiation impact zone on the land region near to the FDNPP. The period during 11-17 March 2011 is considered for the study with the available source term estimates for 137Cs, 134Cs and 113I released during the accident. Simulated high resolution (1km) flow field with nested WRF model was largely westerly from 11 to 14 March. It has been found that the flow changed to northeasterly, easterly and southeasterly on 15 March under the influence of a low pressure and precipitation occurred on 15 March. Dispersion simulations showed the plume moved in a clockwise direction from Pacific Ocean to the land region to the northwest sector of Fukushima resulting in large activity depositions in that sector. The simulations show depositions of 106 to 108 Bq/m2 for 131I and 134Cs; and air dose rates of 10 μSv/h to 100 μSv/h in a distance range of 20 km in the northwest sector of Fukushima prefecture. The model could simulate the observed spike in the instantaneous air dose and its time variation at off-site monitoring stations around the reactor in reasonable agreement with highest doses at Fukushima, Litate located in the northwest sector followed by other sectors. (author)

  3. Advantages of numerical atmospheric dispersion calculations for estimating dispersal and combination effects of stack releases from the nuclear industry

    International Nuclear Information System (INIS)

    An estimation of environmental pollution calculated using the idealized Gaussian distribution model to describe processes of atmospheric diffusion suffers from restrictions in the model, i.e. it assumes stationary homogeneous conditions in the atmosphere, a parallel mean wind flow with no (or at most linear) velocity shear, and constant turbulence characteristics within the plume. These assumptions are oversimplifications: for instance topographic effects, wind shear, time-dependent wind variations and the case of strong local interactions of the pollutant with other components in the atmosphere (e.g. fog, smog, rain, or other pollutant plumes) are ignored. Previous attempts to overcome the disadvantages using a purely numerical evaluation of the differential equations describing the transport, diffusion and any reactions of the pollutants in the atmosphere were unsuccessful, since 'artificial diffusion' effects were observed that led to unacceptable errors when great distances or long times were considered. At present, the best method of solving this problem appears to be the use of a combined Eulerian-Lagrangian numerical approach, called the particle-in-cell method, which was developed in the USA. The method has been tested successfully by making comparisons with typical Gaussian calculations over long time intervals or large distances: it was also applied to several actual transport problems involving complex topographies with wind variations in time, and to the effects of chemical reactions and local rainfall. This method, avoiding the undue simplification of the Gaussian calculation and the inherent fictitious diffusion patterns of the purely numerical evaluation seems to be particularly suited to solving atmospheric pollution transport problems under complex conditions that may occur in the neighbourhood of large nuclear power stations. (author)

  4. Dispersive infrared spectroscopy measurements of atmospheric CO{sub 2} using a Fabry–Pérot interferometer sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K.L. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Ning, Z., E-mail: zhining@cityu.edu.hk [School of Energy and Environment, City University of Hong Kong (Hong Kong); Guy Carpenter Climate Change Centre, City University of Hong Kong (Hong Kong); Westerdahl, D. [Ability R and D Energy Research Centre, City University of Hong Kong (Hong Kong); Wong, K.C. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Sun, Y.W. [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei (China); Hartl, A. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Wenig, M.O. [Meteorological Institute, Ludwig-Maximilians-Universität Munich (Germany)

    2014-02-01

    In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO{sub 2}) using a new scanning Fabry–Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3900 nm to 5220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO{sub 2} absorption band (∼ 4280 nm) and sampling resolution of 20 nm. The CO{sub 2} concentration is determined from the measured optical absorption spectra by fitting it to the CO{sub 2} reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H{sub 2}O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO{sub 2} measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO{sub 2} measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO{sub 2} analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO{sub 2} measurement featuring high accuracy, correction of non-linear absorption and interference of water

  5. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    OpenAIRE

    J. Kukkonen; J. Nikmo; Sofiev, M.; Riikonen, K.; T. Petäjä; A. Virkkula; J. Levula; S. Schobesberger; D. M. Webber

    2014-01-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model p...

  6. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    OpenAIRE

    J. Kukkonen; J. Nikmo; Sofiev, M.; Riikonen, K.; T. Petäjä; A. Virkkula; J. Levula; S. Schobesberger; D. M. Webber

    2014-01-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with t...

  7. Analysis of a Kalman filter based method for on-line estimation of atmospheric dispersion parameters using radiation monitoring data

    International Nuclear Information System (INIS)

    A Kalman filter method is discussed for on-line estimation of radioactive release and atmospheric dispersion from a time series of off-site radiation monitoring data. The method is based on a state space approach, where a stochastic system equation describes the dynamics of the plume model parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent parameter estimates with large associated uncertainties. Improved source term assessment results, when independent estimates of the plume height can be used. Perspectives for using the method in the context of nuclear emergency management are discussed, and possible extensions to the present modelling scheme are outlined, to account for realistic accident scenarios. (authors)

  8. STUDY OF ACCIDENTAL RELEASES HEAVY GAS DISPERSION COMPARING SLAB MODELS AND SCREEN-3 MODEL

    Directory of Open Access Journals (Sweden)

    Prof.V.A.Bhosale

    2015-01-01

    Full Text Available Most of the chemical industries such as petroleum industries, refinery industries, fertilizer industries etc. releases rarely accidental gases it may be heavy gases like liquefied petroleum gas, chlorine, natural gas, ammonia etc do occur. The impact of these heavy gases (high molecular weight than air in the surrounding atmosphere is very harmful/ hazardous to the human health because the formation of heavy clouds of the respective gases nears the earth surface. In present paper, considered the effect of atmospheric parameter such as, direction of air, wind speed etc. as well as stack parameter like height of stack and released gas parameter as density, venting speed of the gas on the dispersion of heavy gas in to the surrounding. Here present work done to identify the downwind concentration along with the horizontal distances through a case study of industrial accidental release (Ammonia Gas scenario. SLAB model for the heavy gas dispersion and SCREEN-3 a single source Gaussian plume model these two types of dispersion models readily available in the public domain for industrial releases of gases. Result of downwind concentration of ammonia vapour in both of model has presented.

  9. Comparison of different estimation methods of accident atmospheric dispersion factors for a representative inland nuclear power plant

    International Nuclear Information System (INIS)

    The applicability of atmospheric diffusion models in complex terrains and low wind speed conditions was discussed in this paper. The accident atmospheric dispersion factors (ATFs) of Taohuajiang nuclear power plant were calculated by using two methods: the probabilistic method recommended by the U.S. Nuclear regulatory Commission (NRC) and the three dimensional objective diagnostic wind field model coupled with Lagrangian trajectory puff model to simulate the 8760 hourly emissions of radioactive nuclides. The results indicate that the maximum hourly accident ATFs calculated by the probabilistic method are conservative in exclusion area boundary (EAB). However, in some directions, accident ATFs calculated using probabilistic method is smaller than that using Lagrangian puff model, as well as some accident ATFs in remote sectors are larger than those in close sectors. Moreover, results calculated by probabilistic method are smaller in long-term release situation. Therefore, accident ATFs obtained according to the regulatory guides may not conservative in some cases, and atmospheric diffusion model should be selected carefully when a nuclear plant is located at a site with complex environmental conditions. (authors)

  10. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident, 2; Verification of the source term and analysis of regional-scale atmospheric dispersion

    OpenAIRE

    寺田 宏明; 堅田 元喜; 茅野 政道; 永井 晴康

    2012-01-01

    Regional-scale atmospheric dispersion simulations were carried out to verify source term of 131I and 137Cs estimated by our previous studies and analyze the atmospheric dispersion during the Fukushima Dai-ichi Nuclear Power Plant accident with measurements of daily and monthly surface depositions over land in Eastern Japan from March 12 to April 30, 2011. The prediction accuracy of daily surface deposition by using the refined source term was mostly within a factor of 10 without apparent bias...

  11. Multilevel modelling of dispersed multiphase flows

    OpenAIRE

    Kuipers, J. A. M.

    2000-01-01

    Dispersed multiphase flows are frequently encountered in a variety of industrially important processes in the petroleum, chemical, metallurgical and energy industries. Scale-up of equipment involving dispersed multiphase flows is quite difficult which is mainly due to the inherent complexity of the prevailing flow phenomena (formation of bubbles and clusters in gas-particle flows). Especially during the last decade significant research efforts have been made in both academic and industrial re...

  12. Air Dispersion Modeling for Building 3026C/D Demolition

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Richard C [ORNL; Sjoreen, Andrea L [ORNL; Eckerman, Keith F [ORNL

    2010-06-01

    This report presents estimates of dispersion coefficients and effective dose for potential air dispersion scenarios of uncontrolled releases from Oak Ridge National Laboratory (ORNL) buildings 3026C, 3026D, and 3140 prior to or during the demolition of the 3026 Complex. The Environmental Protection Agency (EPA) AERMOD system1-6 was used to compute these estimates. AERMOD stands for AERMIC Model, where AERMIC is the American Meteorological Society-EPA Regulatory Model Improvement Committee. Five source locations (three in building 3026D and one each in building 3026C and the filter house 3140) and associated source characteristics were determined with the customer. In addition, the area of study was determined and building footprints and intake locations of air-handling systems were obtained. In addition to the air intakes, receptor sites consisting of ground level locations on four polar grids (50 m, 100 m, 200 m, and 500 m) and two intersecting lines of points (50 m separation), corresponding to sidewalks along Central Avenue and Fifth Street. Three years of meteorological data (2006 2008) were used each consisting of three datasets: 1) National Weather Service data; 2) upper air data for the Knoxville-Oak Ridge area; and 3) local weather data from Tower C (10 m, 30 m and 100 m) on the ORNL reservation. Annual average air concentration, highest 1 h average and highest 3 h average air concentrations were computed using AERMOD for the five source locations for the three years of meteorological data. The highest 1 h average air concentrations were converted to dispersion coefficients to characterize the atmospheric dispersion as the customer was interested in the most significant response and the highest 1 h average data reflects the best time-averaged values available from the AERMOD code. Results are presented in tabular and graphical form. The results for dose were obtained using radionuclide activities for each of the buildings provided by the customer.7

  13. Modelo matemático de dispersão de poluentes na atmosfera: um instrumento técnico para a gestão ambiental Mathematical model of pollutants dispersion in the atmosphere: an instrument technique to environmental management

    Directory of Open Access Journals (Sweden)

    Davidson Moreira

    2004-12-01

    Full Text Available Os modelos matemáticos de dispersão de poluentes na atmosfera representam um instrumento técnico importante, seja para o conhecimento do estado do ambiente, unidos à rede de monitoramento, seja para a gestão ambiental. Neste trabalho são evidenciadas as caraterísticas operacionais e teóricas dos modelos. São introduzidos os modelos de nova geração que podem representar diretamente a turbulência atmosférica através do valor do comprimento de Monin-Obukhov e da velocidade de atrito. Além disso, salienta-se que uma correta utilização dos modelos de transporte e difusão na atmosfera dependem de um estudo sobre suas capacidades de representarem corretamente situações reais confrontando os valores calculados dos modelos com observações experimentais. É aprofundado em particular, visto a grande atualidade do fenômeno, a utilização dos modelos matemáticos de dispersão na gestão da qualidade do ar em ambiente urbano.The mathematical models of pollutant dispersion in the atmosphere represent an important technical instrument, as for the knowledge of the state of the atmosphere, united to the monitoring net, as for the environmental administration. In this work the operational and theoretical characteristics of air pollution models are evidenced. Models of new generation that can represent the atmospheric turbulence directly through the value of the Monin-Obukhov length and of the friction velocity are introduced. Besides, it is pointed out that a correct use of the transport and diffusion models in the atmosphere depends of a study about their capacities of representing real situations confronting the calculated values of the models with experimental observations. It is deepened in matter, seen the great present time of the phenomenon, the use of the mathematical models of dispersion in the management of the air quality in urban environment.

  14. Gas and aerosol radionuclide transfers in complex environments: experimental studies of atmospheric dispersion and interfaces exchanges

    International Nuclear Information System (INIS)

    In situations of chronic or accidental releases, the atmosphere is the main pathway of radioactive releases from nuclear facilities to the environment and, consequently, to humans. It is therefore necessary to have sufficient information on this pathway to accurately assess the radiological impact on man and his environment. Institute for Radioprotection and Nuclear Safety develops its own tools of dispersion and atmospheric transfer for its expertise, under normal operation conditions of a facility, but especially in crisis or post-accident. These tools must have a national and international recognition in particular through scientific validation against benchmark experiments performed internationally, nationally or within the IRSN. The Radioecology Laboratory of Cherbourg-Octeville provides, and will increasingly make, a significant contribution to the scientific influence of the Institute in this field. The work presented in this report has contributed to the development or improvement of experimental techniques in the fields of atmospheric dispersion of radionuclides and transfer at interfaces, in complex environments (complex topography, urban area). These experimental techniques, applied during field campaigns, have allowed to acquire new data in order to get a better understanding of radionuclide transfers in the form of gases and aerosols. (author)

  15. Models of Pluto's upper atmosphere

    International Nuclear Information System (INIS)

    Best guesses as to the thermal structure and composition of Pluto's atmosphere have led to speculations of substantial loss rates (∼1028 s-1) of methane from the planet over cosmogonic time scales. Results from recent stellar occultation measurements, and using a Parker-type hydrodynamic calculation, show that the loss rates may actually be lower by as much as a factor ∼5, depending upon the efficiency of heating of the atmosphere via the absorption of solar EUV and upon the true atmospheric composition, if the thermal structure of the upper atmosphere is properly taken into account. The loss rate may even be less (by another factor ∼10) if there is minimal heating of the upper atmosphere

  16. Real-time modelling of complex atmospheric releases in urban areas

    International Nuclear Information System (INIS)

    If a nuclear installation in or near an urban area has a venting, fire, or explosion, airborne radioactivity becomes the major concern. Dispersion models are the immediate tool for estimating the dose and contamination. Responses in urban areas depend on knowledge of the amount of the release, representative meteorological data, and the ability of the dispersion model to simulate the complex flows as modified by terrain or local wind conditions. A centralised dispersion modelling system can produce realistic assessments of radiological accidents anywhere in a country within several minutes if it is computer-automated. The system requires source-term, terrain, mapping and dose-factor databases, real-time meteorological data acquisition, three-dimensional atmospheric transport and dispersion models, and experienced staff. Experience with past responses in urban areas by the Atmospheric Release Advisory Capability (ARAC) program at Lawrence Livermore National Laboratory illustrate the challenges for three-dimensional dispersion models. (author)

  17. Real-time modeling of complex atmospheric releases in urban areas

    International Nuclear Information System (INIS)

    If a nuclear installation in or near an urban area has a venting, fire, or explosion, airborne radioactivity becomes the major concern. Dispersion models are the immediate tool for estimating the dose and contamination. Responses in urban areas depend on knowledge of the amount of the release, representative meteorological data, and the ability of the dispersion model to simulate the complex flows as modified by terrain or local wind conditions. A centralized dispersion modeling system can produce realistic assessments of radiological accidents anywhere in a country within several minutes if it is computer-automated. The system requires source-term, terrain, mapping and dose-factor databases, real-time meteorological data acquisition, three-dimensional atmospheric transport and dispersion models, and experienced staff. Experience with past responses in urban areas by the Atmospheric Release Advisory Capability (ARAC) program at Lawrence Livermore National Laboratory illustrate the challenges for three-dimensional dispersion models

  18. Dispersion model computations of urban air pollution in Espoo, Finland

    Energy Technology Data Exchange (ETDEWEB)

    Valkonen, E.; Haerkoenen, J.; Kukkonen, J.; Rantakrans, E.; Jalkanen, L.

    1997-12-31

    This report presents the numerical results of air quality studies of the city of Espoo in southern Finland. This city is one of the four cities in the Helsinki metropolitan area, having a total population of 850 000. A thorough emission inventory was made of both mobile and stationary sources in the Helsinki metropolitan area. The atmospheric dispersion was evaluated using an urban dispersion modelling system, including a Gaussian multiple-source plume model and a meteorological pre-processing model. The hourly time series of CO, NO{sub 2} and SO{sub 2} concentrations were predicted, using the emissions and meteorological data for the year 1990. The predicted results show a clear decrease in the yearly mean concentrations from southeast to northwest. This is due in part to the denser traffic in the southern parts of Espoo, and in part to pollution from the neighbouring cities of Helsinki and Vantaa, located east of Espoo. The statistical concentration parameters found for Espoo were lower than the old national air quality guidelines (1984); however, some occurrences of above-threshold values were found for NO{sub 2} in terms of the new guidelines (1996). The contribution of traffic to the total concentrations varies spatially from 30 to 90 % for NO{sub 2} from 1 to 65 % for SO{sub 2} while for CO it is nearly 100 %. The concentrations database will be further utilised to analyse the influence of urban air pollution on the health of children attending selected day nurseries in Espoo. The results of this study can also be applied in traffic and city planning. In future work the results will also be compared with data from the urban measurement network of the Helsinki Metropolitan Area Council. (orig.) 19 refs.

  19. Dispersion analysis with inverse dielectric function modelling.

    Science.gov (United States)

    Mayerhöfer, Thomas G; Ivanovski, Vladimir; Popp, Jürgen

    2016-11-01

    We investigate how dispersion analysis can profit from the use of a Lorentz-type description of the inverse dielectric function. In particular at higher angles of incidence, reflectance spectra using p-polarized light are dominated by bands from modes that have their transition moments perpendicular to the surface. Accordingly, the spectra increasingly resemble inverse dielectric functions. A corresponding description can therefore eliminate the complex dependencies of the dispersion parameters, allow their determination and facilitate a more accurate description of the optical properties of single crystals. PMID:27294550

  20. Ship plume dispersion rates in convective boundary layers for chemistry models

    Directory of Open Access Journals (Sweden)

    F. Chosson

    2008-08-01

    Full Text Available Detailed ship plume simulations in various convective boundary layer situations have been performed using a Lagrangian Dispersion Model driven by a Large Eddy Simulation Model. The simulations focus on the early stage (1–2 h of plume dispersion regime and take into account the effects of plume rise on dispersion. Results are presented in an attempt to provide to atmospheric chemistry modellers a realistic description of characteristic dispersion impact on exhaust ship plume chemistry. Plume dispersion simulations are used to derive analytical dilution rate functions. Even though results exhibit striking effects of plume rise parameter on dispersion patterns, it is shown that initial buoyancy fluxes at ship stack have a minor effect on plume dilution rate. After initial high dispersion regimes a simple characteristic dilution time scale can be used to parameterize the subgrid plume dilution effect in large-scale chemistry models. The results show that this parameter is directly related to the typical turn-over time scale of the convective boundary layer.

  1. Dynamic Model of the Price Dispersion of Homogeneous Goods

    OpenAIRE

    Kaldasch, Joachim

    2015-01-01

    Presented is an analytic microeconomic model of the temporal price dispersion of homogeneous goods in polypoly markets. This new approach is based on the idea that the price dispersion has its origin in the dynamics of the purchase process. The price dispersion is determined by the chance that demanded and supplied product units meet in a given price interval. It can be characterized by a fat-tailed Laplace distribution for short and by a lognormal distribution for long time horiz...

  2. Viscosity model of high-viscosity dispersing system

    Institute of Scientific and Technical Information of China (English)

    魏先福; 王娜; 黄蓓青; 孙承博

    2008-01-01

    High-viscosity dispersing system is formed by dispersing the solid particles in the high-viscosity continuous medium.It is very easy to form the three-dimensional network structure for solid particles in the system and the rheology behavior becomes complicated.The apparent viscosity of this dispersing system always has the connection with the volume ratio and the shear rate.In order to discuss the rheology behavior and put up the viscosity model,the suspension of silicon dioxide and silicon oil were prepared.Through testing the viscosity,the solid concentration and the shear rate,the effects of the ratio and the shear rate on viscosity was analyzed,the model of the high-viscosity dispersing system was designed and the model with the printing ink were validated.The experiment results show that the model is applicable to the high-viscosity dispersing systems.

  3. Modeling CO2 air dispersion from gas driven lake eruptions

    Science.gov (United States)

    Chiodini, Giovanni; Costa, Antonio; Rouwet, Dmitri; Tassi, Franco

    2016-04-01

    The most tragic event of gas driven lake eruption occurred at Lake Nyos (Cameroon) on 21 August 1986, when a dense cloud of CO2 suffocated more than 1700 people and an uncounted number of animals in just one night. The event stimulated a series of researches aimed to understand gas origins, gas release mechanisms and strategies for gas hazard mitigation. Very few studies have been carried out for describing the transport of dense CO2 clouds in the atmosphere. Although from a theoretical point of view, gas dispersion can be fully studied by solving the complete equations system for mass, momentum and energy transport, in actual practice, different simplified models able to describe only specific phases or aspects have to be used. In order to simulate dispersion of a heavy gas and to assess the consequent hazard we used a model based on a shallow layer approach (TWODEE2). This technique which uses depth-averaged variables to describe the flow behavior of dense gas over complex topography represents a good compromise between the complexity of computational fluid dynamic models and the simpler integral models. Recently the model has been applied for simulating CO2 dispersion from natural gas emissions in Central Italy. The results have shown how the dispersion pattern is strongly affected by the intensity of gas release, the topography and the ambient wind speed. Here for the first time we applied TWODEE2 code to simulate the dispersion of the large CO2 clouds released by limnic eruptions. An application concerns the case of the 1986 event at lake Nyos. Some difficulties for the simulations were related to the lack of quantitative information: gas flux estimations are not well constrained, meteorological conditions are only qualitatively known, the digital model of the terrain is of poor quality. Different scenarios were taken into account in order to reproduce the qualitative observations available for such episode. The observations regard mainly the effects of gas on

  4. NARAC Dispersion Model Product Integration With RadResponder

    Energy Technology Data Exchange (ETDEWEB)

    Aluzzi, Fernando [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-30

    Work on enhanced cooperation and interoperability of Nuclear Incident Response Teams (NIRT) is a joint effort between DHS/FEMA, DOE/NNSA and EPA. One such effort was the integration between the RadResponder Network, a resource sponsored by FEMA for the management of radiological data during an emergency, and the National Atmospheric Advisory Center (NARAC), a DOE/NNSA modeling resource whose predictions are used to aid radiological emergency preparedness and response. Working together under a FEMA-sponsored project these two radiological response assets developed a capability to read and display plume model prediction results from the NARAC computer system in the RadResponder software tool. As a result of this effort, RadResponder users have been provided with NARAC modeling predictions of contamination areas, radiological dose levels, and protective action areas (e.g., areas warranting worker protection or sheltering/evacuation) to help guide protective action decisions and field monitoring surveys, and gain key situation awareness following a radiological/nuclear accident or incident (e.g., nuclear power plant accident, radiological dispersal device incident, or improvised nuclear detonation incident). This document describes the details of this integration effort.

  5. Evaluation of the ERP dispersion model using Darlington tracer-study data. Report No. 90-200-K

    Energy Technology Data Exchange (ETDEWEB)

    Wright, S.C.

    1990-01-01

    In this study, site-boundary atmospheric dilution factors calculated by the atmospheric dispersion model used in the ERP (Emergency Response Planning) computer code were compared to data collected during the Darlington tracer study. The purpose of this comparison was to obtain estimates of model uncertainty under a variety of conditions. This report provides background on ERP, the ERP dispersion model and the Darlington tracer study. Model evaluation techniques are discussed briefly, and the results of the comparison of model calculations with the field data are presented and reviewed.

  6. Emulation of simulations of atmospheric dispersion at Fukushima for Sobol' sensitivity analysis

    Science.gov (United States)

    Girard, Sylvain; Korsakissok, Irène; Mallet, Vivien

    2015-04-01

    Polyphemus/Polair3D, from which derives IRSN's operational model ldX, was used to simulate the atmospheric dispersion at the Japan scale of radionuclides after the Fukushima disaster. A previous study with the screening method of Morris had shown that - The sensitivities depend a lot on the considered output; - Only a few of the inputs are non-influential on all considered outputs; - Most influential inputs have either non-linear effects or are interacting. These preliminary results called for a more detailed sensitivity analysis, especially regarding the characterization of interactions. The method of Sobol' allows for a precise evaluation of interactions but requires large simulation samples. Gaussian process emulators for each considered outputs were built in order to relieve this computational burden. Globally aggregated outputs proved to be easy to emulate with high accuracy, and associated Sobol' indices are in broad agreement with previous results obtained with the Morris method. More localized outputs, such as temporal averages of gamma dose rates at measurement stations, resulted in lesser emulator performances: tests simulations could not satisfactorily be reproduced by some emulators. These outputs are of special interest because they can be compared to available observations, for instance for calibration purpose. A thorough inspection of prediction residuals hinted that the model response to wind perturbations often behaved in very distinct regimes relatively to some thresholds. Complementing the initial sample with wind perturbations set to the extreme values allowed for sensible improvement of some of the emulators while other remained too unreliable to be used in a sensitivity analysis. Adaptive sampling or regime-wise emulation could be tried to circumvent this issue. Sobol' indices for local outputs revealed interesting patterns, mostly dominated by the winds, with very high interactions. The emulators will be useful for subsequent studies. Indeed

  7. EXAMPLE APPLICATION OF CFD SIMULATIONS FOR SHORT-RANGE ATMOSPHERIC DISPERSION OVER THE OPEN FIELDS OF PROJECT PRAIRIE GRASS

    Science.gov (United States)

    Computational Fluid Dynamics (CFD) techniques are increasingly being applied to air quality modeling of short-range dispersion, especially the flow and dispersion around buildings and other geometrically complex structures. The proper application and accuracy of such CFD techniqu...

  8. Global Risk from the Atmospheric Dispersion of Radionuclides by Nuclear Power Plant Accidents in the Coming Decades

    Science.gov (United States)

    Christoudias, T.; Proestos, Y.; Lelieveld, J.

    2014-12-01

    We estimate the global risk from the release and atmospheric dispersion of radionuclides from nuclear power plant accidents using the EMAC atmospheric chemistry-general circulation model. We included all nuclear reactors that are currently operational, under construction and planned or proposed. We implemented constant continuous emissions from each location in the model and simulated atmospheric transport and removal via dry and wet deposition processes over 20 years (2010-2030), driven by boundary conditions based on the IPCC A2 future emissions scenario. We present global overall and seasonal risk maps for potential surface layer concentrations and ground deposition of radionuclides, and estimate potential doses to humans from inhalation and ground-deposition exposures to radionuclides. We find that the risk of harmful doses due to inhalation is typically highest in the Northern Hemisphere during boreal winter, due to relatively shallow boundary layer development and limited mixing. Based on the continued operation of the current nuclear power plants, we calculate that the risk of radioactive contamination to the citizens of the USA will remain to be highest worldwide, followed by India and France. By including stations under construction and those that are planned and proposed, our results suggest that the risk will become highest in China, followed by India and the USA.

  9. THE ROLE OF THE METEO-CLIMATIC FACTORS IN THE DISPERSION OF ATMOSPHERIC POLLUTANTS

    Directory of Open Access Journals (Sweden)

    Liviu Apostol

    2007-10-01

    Full Text Available The atmospheric pollution and de-pollution phenomena are influenced by a series of factors, among which, the most important are: the characteristics of the emission, the meteorological factors, the geographical factors and the anthropic factors. The meteorological factors influence the transport, depositing, dispersion or stagnation of the pollutants. In time, under the influence of the physical and chemical factors specific to the atmosphere, or through reactions with other pollutants, a pollutant usually changes its chemical nature. Among the meteorological factors with influence on the pollution, in the present paper we will analyze the precipitation and the wind. The air currents, especially the horizontal ones, are considered among the most important dispersion factors. The aim of the present paper is that of proposing a simple and efficient way of interpreting the role of wind and atmospheric precipitations in the atmospheric pollution and depollution. All the examples (for the predominant wind direction, for atmospheric calmness, for different precipitation characteristics and for different characteristics of the emission sources were given for the territory of Piatra Neamţ municipality. The municipality of Piatra Neamţ is situated at the emergence of the Bistriţa River from the mountain area, and it stretches out over 16 km from west to east and 8 km from north to south, with altitudes between 290 and 851 m. The western part is situated on the mountain corridor of the Bistriţa and the eastern part, in the Cracău – Bistriţa Depression. The main polluting sources are the chemical platform situated in the central-southern part of the proper urban area. Our research took was done in the period 1983 – 2003, by means of 15 stations for collecting the pollutants, and a meteorological network with continuous recording of the main climatic parameters, as well as a meteorological station. These were placed in very representative places

  10. Dispersion of aerosol particles in the free atmosphere using ensemble forecasts

    Directory of Open Access Journals (Sweden)

    T. Haszpra

    2013-10-01

    Full Text Available The dispersion of aerosol particle pollutants is studied using 50 members of an ensemble forecast in the example of a hypothetical free atmospheric emission above Fukushima over a period of 2.5 days. Considerable differences are found among the dispersion predictions of the different ensemble members, as well as between the ensemble mean and the deterministic result at the end of the observation period. The variance is found to decrease with the particle size. The geographical area where a threshold concentration is exceeded in at least one ensemble member expands to a 5–10 times larger region than the area from the deterministic forecast, both for air column "concentration" and in the "deposition" field. We demonstrate that the root-mean-square distance of any particle from its own clones in the ensemble members can reach values on the order of one thousand kilometers. Even the centers of mass of the particle cloud of the ensemble members deviate considerably from that obtained by the deterministic forecast. All these indicate that an investigation of the dispersion of aerosol particles in the spirit of ensemble forecast contains useful hints for the improvement of risk assessment.

  11. Final Report for the Joint Urban 2003 Atmospheric Dispersion Study in Oklahoma City: Lawrence Livermore National Laboratory participation

    Energy Technology Data Exchange (ETDEWEB)

    Leach, M J

    2005-10-12

    The Joint Urban 2003 (JU2003) field study was designed to collect meteorological and tracer data resolving atmospheric dispersion at scales-of-motion ranging from flows in and around a single city block, in and around several blocks in the downtown Central Business District (CBD), and into the suburban Oklahoma City area a few km from the CBD. Indoor tracer and flow measurements within four downtown study buildings were also made in conjunction with detailed outdoor measurements investigating the outdoor-indoor exchange rates and mechanisms. The movement of tracer within the study buildings was also studied. The data from the field experiment is being used to evaluate models that are being developed for predicting dispersion of contaminants in urban areas. These models may be fast-response models based on semi-empirical algorithms that are used in real-time emergencies, or highly sophisticated computational fluid dynamics models that resolve individual building faces and crevices. The data from the field experiment, together with the models, can then be used to develop other advanced tools that are especially valuable in the efforts to thwart terrorists. These include tools for finding location and characteristics of a contaminant source; tools that can be used for real-time response or for forensic investigation. The tools will make use of monitoring networks for biological agents that are being established in several sensitive cities throughout the nation. This major urban study was conducted beginning June 28 and ending July 31, 2003. It included several integrated scientific components necessary to describe and understand the physical processes governing dispersion within and surrounding an urban area and into and within building environments. The components included characterizing: (1) the urban boundary layer and the development of the urban boundary layer within the atmospheric boundary layer, (2) the flows within and downwind of the tall-building core, (3

  12. ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

    International Nuclear Information System (INIS)

    Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation

  13. Modelling surface radioactive spill dispersion in the Alboran Sea

    Energy Technology Data Exchange (ETDEWEB)

    Perianez, R. [Dpto. Fisica Aplicada I, E.U. Ingenieria Tecnica Agricola, Universidad de Sevilla. Ctra. Utrera km 1, 41013 Sevilla (Spain)]. E-mail: rperianez@us.es

    2006-07-01

    The Strait of Gibraltar and the Alboran Sea are the only connection between the Atlantic Ocean and the Mediterranean Sea. Intense shipping activities occur in the area, including transport of waste radionuclides and transit of nuclear submarines. Thus, it is relevant to have a dispersion model that can be used in an emergency situation after an accident, to help the decision-making process. Such dispersion model requires an appropriate description of the physical oceanography of the region of interest, with simulations of tides and residual (average) circulation. In this work, a particle-tracking dispersion model that can be used to simulate the dispersion of radionuclides in the system Strait of Gibraltar-Alboran Sea is described. Tides are simulated using a barotropic model and for the average circulation a reduced-gravity model is applied. This model is able to reproduce the main features of the Alboran circulation (the well known Western Alboran Gyre, WAG, and the coastal circulation mode). The dispersion model is run off-line, using previously computed tidal and residual currents. The contamination patch is simulated by a number of particles whose individual paths are computed; diffusion and decay being modelled using a Monte Carlo method. Radionuclide concentrations may be obtained from the density of particles per water volume unit. Results from the hydrodynamic models have been compared with observations in the area. Several examples of dispersion computations under different wind and circulation conditions are presented.

  14. Modelling long-distance seed dispersal in heterogeneous landscapes.

    Energy Technology Data Exchange (ETDEWEB)

    Levey, Douglas, J.; Tewlsbury, Joshua, J.; Bolker, Benjamin, M.

    2008-01-01

    1. Long-distance seed dispersal is difficult to measure, yet key to understanding plant population dynamics and community composition. 2. We used a spatially explicit model to predict the distribution of seeds dispersed long distances by birds into habitat patches of different shapes. All patches were the same type of habitat and size, but varied in shape. They occurred in eight experimental landscapes, each with five patches of four different shapes, 150 m apart in a matrix of mature forest. The model was parameterized with smallscale movement data collected from field observations of birds. In a previous study we validated the model by testing its predictions against observed patterns of seed dispersal in real landscapes with the same types and spatial configuration of patches as in the model. 3. Here we apply the model more broadly, examining how patch shape influences the probability of seed deposition by birds into patches, how dispersal kernels (distributions of dispersal distances) vary with patch shape and starting location, and how movement of seeds between patches is affected by patch shape. 4. The model predicts that patches with corridors or other narrow extensions receive higher numbers of seeds than patches without corridors or extensions. This pattern is explained by edgefollowing behaviour of birds. Dispersal distances are generally shorter in heterogeneous landscapes (containing patchy habitat) than in homogeneous landscapes, suggesting that patches divert the movement of seed dispersers, ‘holding’ them long enough to increase the probability of seed defecation in the patches. Dispersal kernels for seeds in homogeneous landscapes were smooth, whereas those in heterogenous landscapes were irregular. In both cases, long-distance (> 150 m) dispersal was surprisingly common, usually comprising approximately 50% of all dispersal events. 5. Synthesis . Landscape heterogeneity has a large influence on patterns of long-distance seed dispersal. Our

  15. Modelling the observed vertical transport of 7Be in specific soils with advection dispersion model

    International Nuclear Information System (INIS)

    7Be is a short-lived environmental radionuclide, produced in the upper atmosphere by spallation of nitrogen and oxygen by cosmic rays. After of the production by the nuclear reaction, 7Be diffuses through the atmosphere until it attaches to atmospheric aerosols. Subsequently, it is deposited on the earth surface mainly as wet fallout. The main physical processes which transport 7Be in soil are diffusion and advection by water. Migration parameters and measurements confirm that sorption is the main physical process, which confines 7Be concentration to soil surface. The literature data show that in soils, 7Be is concentrated near the surface (0-2 cm) as it is adsorbed onto clay minerals after its deposition on the soil surface and does not penetrate deeper into soils due to its short half-life. The maximum mass activity density of 7Be is found at the point of input of the radionuclide, i.e. at the surface of the soil column, showing a exponential distribution profile typical of a purely diffusive transport. Many studies applying the advection dispersion models have been reported in the literature in order to modelling the transport of 137Cs in soils. On them, the models are used to achieve information of the mechanisms that govern the transport, i. e. the model is used to explain the soil profile of radionuclide. The effective dispersion coefficient and the apparent advection velocity of radionuclide in soil are also obtained by fitting the analytical solution of the model equation to measured depth distributions of the radionuclide. In this work, the advective dispersive transport model with linear sorption is used to analyze the vertical migration process of 7Be in soils of undisturbed or reference sites. The deposition history is approximated by pulse-like input functions and time dependent analytical solution of equation model is obtained. The values of dispersion coefficient and apparent advection velocity obtained by fitting experimental profiles are compared

  16. Mirage, a food chain transfer and dosimetric impact code in relation with atmospheric and liquid dispersion codes

    International Nuclear Information System (INIS)

    Full text: The numerical code M.I.R.A.G.E. (Module of Radiological impact calculations on the Environment due to accidental or chronic nuclear releases through Aqueous and Gas media) has been developed to simulate the radionuclides transfer in the biosphere and food chains, as well as the dosimetric impact on man, after accidental or chronic releases in the environment by nuclear installations. The originality of M.I.R.A.G.E. is to propose a single tool chained downstream with various atmospheric and liquid dispersion codes. The code M.I.R.A.G.E. is a series of modules which makes it possible to carry out evaluations on the transfers in food chains and human dose impact. Currently, M.I.R.A.G.E. is chained with a Gaussian atmospheric dispersion code H.A.R.M.A.T.T.A.N. (Cea), a 3 D atmospheric dispersion code with Lagrangian model named M.I.N.E.R.V.E.-S.P.R.A.Y. (Aria Technology) and a 3 D groundwater transfer code named M.A.R.T.H.E. (B.R.G.M.). M.I.R.A.G.E. uses concentration or activity result files as initial data input for its calculations. The application initially calculates the concentrations in the various compartments of the environment (soils, plants, animals). The results are given in the shape of concentration and dose maps and also on a particular place called a reference group for dosimetric impact (like a village or a specific population group located around a nuclear installation). The input and output data of M.I.R.A.G.E. can have geographic coordinates and thus readable by a G.I.S. M.I.R.A.G. E.is an opened system with which it is easy to chain other codes of dispersion that those currently used. The calculations uncoupled with dispersion calculations are also possible by manual seizure of the dispersion data (contamination of a tablecloth, particular value in a point, etc.). M.I.R.A.G.E. takes into account soil deposits and resuspension phenomenon, transfers in plants and animals (choice of agricultural parameters, types of plants and animals, etc

  17. Dispersive processes in models of regional radionuclide migration. Technical memorandum

    International Nuclear Information System (INIS)

    Three broad areas of concern in the development of aquifer scale transport models will be local scale diffusion and dispersion processes, regional scale dispersion processes, and numerical problems associated with the advection-dispersion equation. Local scale dispersion processes are fairly well understood and accessible to observation. These processes will generally be dominated in large scale systems by regional processes, or macro-dispersion. Macro-dispersion is primarily the result of large scale heterogeneities in aquifer properties. In addition, the effects of many modeling approximations are often included in the process. Because difficulties arise in parameterization of this large scale phenomenon, parameterization should be based on field measurements made at the same scale as the transport process of interest or else partially circumvented through the application of a probabilistic advection model. Other problems associated with numerical transport models include difficulties with conservation of mass, stability, numerical dissipation, overshoot, flexibility, and efficiency. We recommend the random-walk model formulation for Lawrence Livermore Laboratory's purposes as the most flexible, accurate and relatively efficient modeling approach that overcomes these difficulties

  18. Aquatic dispersion modelling of a tritium plume in Lake Ontario

    International Nuclear Information System (INIS)

    Approximately 2900 kg of tritiated water, containing 2.3E+15 Bq of tritium, were released to Lake Ontario via the cooling water discharge when a leak developed in a moderator heat exchanger in Unit 1 at the Pickering Nuclear Generating Station (PNGS) on 1992 August 2. The release provided the opportunity to study the dispersion of a tritium plume in the coastal zone of Lake Ontario. Current direction over the two-week period following the release was predominantly parallel to the shore, and elevated tritium concentrations were observed up to 20 km east and 85 km west of the PNGS. Predictions of the tritium plume movement were made using current velocity measurements taken at 8-m depth, 2.5 km offshore from Darlington and using a empirical relationship where alongshore current speed is assumed to be proportional to the alongshore component of the wind speed. The tritium migration was best described using current velocity measurements. The tritium plume dispersion is modelled using the one-dimensional advection-dispersion equation. Transport parameters are the alongshore current speed and longitudinal dispersion coefficient. Longitudinal dispersion coefficients, estimated by fitting the solution of the advection-dispersion equation to measured concentration distance profiles ranged from 3.75 to 10.57 m2s-1. Simulations using the fitted values of the dispersion coefficient were able to describe maximum tritium concentrations measured at water supply plants located within 25 km of Pickering to within a factor of 3. The dispersion coefficient is a function of spatial and temporal variability in current velocity and the fitted dispersion coefficients estimated here may not be suitable for predicting tritium plume dispersion under different current conditions. The sensitivity of the dispersion coefficient to variability in current conditions should be evaluated in further field experiments. (author). 13 refs., 7 tabs., 12 figs

  19. Source term for atmospheric dispersion in pipeline rupture; Termo fonte para dispersao atmosferica em ruptura de gasoduto

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Rubem da Cunha [Pontificia Univ. Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil). Faculdade de Engenharia. Dept. de Engenharia Quimica]. E-mail: rreis@eq.pucrs.br; Leal, Cesar Antonio [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Dept. de Engenharia Nuclear. Programa de Pos-graduacao em Engenharia Mecanica]. E-mail: leal@vortex.ufrgs.br

    2003-07-01

    The evaluation of consequences of industrial accidents requires the determination of physical effects in the several stages that compose a sequence of events that needs to be modeled. When a dangerous product is liberated accidentally, in order to the estimate of the possible number of victims in the scenario under consideration, one needs to evaluate the amount of released material, its physical state, and the amount that becomes airborne to form the source term for dispersion. Natural gas, transported in pipelines, is already crossing the state of Rio Grande do Sul, where, as well as in another areas of the country, it will be widely used. The need to overcome large distances between distribution and consuming units of natural gas implies in the use of high pressure conditions for transportation. The modeling of the behavior of the system in case of an accidents under this condition of quite severe pressure was done in a similar fashion used in a previous work where good results were obtained. The pipeline initial conditions are supercritical. In this paper, it is presented a discussion and results of the amount of natural gas that would be liberated in the form gas for further dispersion in the atmosphere, for the case of a pipeline initially in the pressure of 7 MPa and ambient temperature. (author)

  20. RETADDII: modeling long-range atmospheric transport of radionuclides

    International Nuclear Information System (INIS)

    A versatile model is described which estimates atmospheric dispersion based on plume trajectories calculated for the mixed layer. This model allows the treatment of the dispersal from a source at an arbitrary height while taking account of plume depletion by dry and wet deposition together with the decay of material to successor species. The plume depletion, decay and growth equations are solved in an efficient manner which can accommodate up to eight pollutants (i.e. a parent and seven serial decay products). The code is particularly suitable for applications involving radioactive chain decay or for cases involving chemical species with successor decay products. Arbitrary emission rates can be specified for the members of the chain or, as is commonly the case, a sole emission rate can be specified for the first member. The code, in its current configuration, uses readily available upper-air wind data for the North American continent

  1. Wind tunnel simulation of atmospheric dispersion in stable conditions at a real site

    International Nuclear Information System (INIS)

    The flow visualisation technique developed at Ecole Centrale de Lyon has been used for the study of a plume dispersion on a site simulating the experiment field work by CRABOL. Very stable situations could be reached by cooling the surface of the model with liquid nitrogen. Quasi-laminar flows were obtained with these conditions, while the neutral and slightly stable cases performed fully turbulent flows. Results on the velocity and concentration fields ae given and compared with the field data. (author)

  2. Comparative analysis of three atmospheric dispersion coefficient systems at the Angra dos Reis, RJ, region

    International Nuclear Information System (INIS)

    A comparative analysis was made in this work among Pasquill-Gifford (PG) atmospheric dispersion coefficients and those determined at the Juelich and Karlsruhe sites with the purpose of suggesting which one would be the most applicable to the Angra site. Each one of the three systems was determined by different experiments, carried out over sites with diversified features. The systems of Juelich and Karlsruhe were obtained over sites with high surface roughness and from stacks (elevated releases), while the PG system was obtained over sites with a small surface roughness and from ground level releases. The results of the application of these systems at a complex site like Angra,which has a highly diversified structure encompassing sea, vegetation, predominance of light winds and stable stability classes, show that the PG system, the most used in the world, is still the best choice. (author)

  3. Soil-vegetation-atmosphere transfer modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ikonen, J.P.; Sucksdorff, Y. [Finnish Environment Agency, Helsinki (Finland)

    1996-12-31

    In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

  4. Model for the simulation of the interface dispersion

    International Nuclear Information System (INIS)

    Two models - basically different in their treatment of the two-phase flow - are coupled together to simulate transients with the dispersion of the interface. The Volume of Fluid (VOF) model, uses an interface-tracking algorithm for the simulation of the two-phase flow, can be used only as long as a local grid density allows surface tracking. Second model -'twofluid' model - is based on less accurate equations averaged in time and space and does not track the interface explicitly and is more suitable for simulations of dispersed flow. A Rayleigh-Taylor instability is used as a representative problem for the test of the coupled model, where long time development of the instability causes mixing of the fluids and dispersion of the interface. Grid refinement studies are made to examine the mechanism of the switch between models and to check the convergence of the physical characteristic. (author)

  5. Biomonitoring of airborne particulate matter emitted from a cement plant and comparison with dispersion modelling results

    Science.gov (United States)

    Abril, Gabriela A.; Wannaz, Eduardo D.; Mateos, Ana C.; Pignata, María L.

    2014-01-01

    The influence of a cement plant that incinerates industrial waste on the air quality of a region in the province of Córdoba, Argentina, was assessed by means of biomonitoring studies (effects of immission) and atmospheric dispersion (effects of emission) of PM10 with the application of the ISC3 model (Industrial Source Complex) developed by the USEPA (Environmental Protection Agency). For the biomonitoring studies, samples from the epiphyte plant Tillandsia capillaris Ruíz & Pav. f. capillaris were transplanted to the vicinities of the cement plant in order to determine the physiological damage and heavy metal accumulation (Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb). For the application of the ISC3 model, point and area sources from the cement plant were considered to obtain average PM10 concentration results from the biomonitoring exposure period. This model permitted it to be determined that the emissions from the cement plant (point and area sources) were confined to the vicinities, without significant dispersion in the study area. This was also observed in the biomonitoring study, which identified Ca, Cd and Pb, pH and electric conductivity (EC) as biomarkers of this cement plant. Vehicular traffic emissions and soil re-suspension could be observed in the biomonitors, giving a more complete scenario. In this study, biomonitoring studies along with the application of atmospheric dispersion models, allowed the atmospheric pollution to be assessed in more detail.

  6. Modelling the atmospheric chemistry of volcanic plumes

    OpenAIRE

    Surl, Luke

    2016-01-01

    Abstract Volcanoes are the principal way by which volatiles are transferred from the solid Earth to the atmosphere-hydrosphere system. Once released into the atmosphere, volcanic emissions rapidly undergo a complex series of chemical reactions. This thesis seeks to further the understanding of such processes by both observation and numerical modelling. I have adapted WRF-Chem to model passive degassing from Mount Etna, the chemistry of its plume, and its influence on the ...

  7. CFD Modeling of Particulate Matter Dispersion from Kerman Cement Plant

    Directory of Open Access Journals (Sweden)

    M. Panahandeh

    2010-04-01

    Full Text Available "n "n "nBackgrounds and Objectives: The dispersion of particulate matter has been known as the most serious environmental pollution of cement plants. In the present work, dispersion of the particulate matter from stack of Kerman Cement Plant was investigated using Computational Fluid Dynamics (CFD modeling."nMaterials and Methods: In order to study the dispersion of particulate matter from the stack, a calculation domain with dimensions of 8000m × 800m × 400m was considered. The domain was divided to 936781 tetrahedral control volumes. The mixture two-phase model was employed to model the interaction of the particulate matter (dispersed phase and air (continuous phase. The Large Eddy Simulation (LES method was used for turbulence modeling."nResults: The concentration of particulate matter in the whole calculation domain was computed. The predicted concentrations were compared to the measured values from the literature and a good agreement was observed. The predicted concentration profiles at different cross sections were analyzed."nConclusion:The results of the present work showed that CFD is a useful tool for understanding the dispersion of particulate matter in air. Although the obtained results were promising, more investigations on the properties of the dispersed phase, turbulent parameters and the boundary layer effect is needed to obtain more accurate results.

  8. Modelling the dispersion energy for Van der Waals complexes

    CERN Document Server

    Sanz-Garcia, A

    2002-01-01

    Strictly ab initio calculations of the dispersion energy are unfeasible in practice but for the smallest systems. A sensible alternative is to model the dispersion contribution through a damped multipolar expansion. This thesis proposes to represent the dispersion energy by means of a non-empirical, atom-atom model using damping functions scaled from 'exact' results for one electron-one electron systems. We start by investigating the scalability of ab initio calculated damping functions for closed-shell atom-atom dimers. Ab initio scaling parameters are employed to assess the quality of the damping functions yielded by a predictor scheme based on the charge overlap between the interacting monomers. The investigation of the scaling properties is extended to atom-linear molecule systems, focusing on the dependence on orientation of the short-range dispersion energy and how to account for it using isotropic damping parameters. We study the possibilities of an 'atomic' (multicentre) representation of the dispersi...

  9. Chemical uncertainties in modeling hot Jupiters atmospheres

    Science.gov (United States)

    Hebrard, Eric; Domagal-Goldman, Shawn

    2015-11-01

    Most predictions and interpretations of observations in beyond our Solar System have occurred through the use of 1D photo-thermo-chemical models. Their predicted atmospheric compositions are highly dependent on model parameters. Chemical reactions are based on empirical parameters that must be known at temperatures ranging from 100 K to above 2500 K and at pressures from millibars to hundreds of bars. Obtained from experiments, calculations and educated-guessed estimations, these parameters are always evaluated with substantial uncertainties. However, although of practical use, few models of exoplanetary atmospheres have considered these underlying chemical uncertainties and their consequences. Recent progress has been made recently that allow us to (1) evaluate the accuracy and precision of 1D models of planetary atmospheres, with quantifiable uncertainties on their predictions for the atmospheric composition and associated spectral features, (2) identify the ‘key parameters’ that contribute the most to the models predictivity and should therefore require further experimental or theoretical analysis, (3) reduce and optimize complex chemical networks for their inclusion in multidimensional atmospheric models.First, a global sampling approach based on low discrepancy sequences has been applied in order to propose error bars on simulations of the atmospheres HD 209458b and HD 189733b, using a detailed kinetic model derived from applied combustion models that was methodically validated over a range of temperatures and pressures typical for these hot Jupiters. A two-parameters temperature-dependent uncertainty factor has been assigned to each considered rate constant. Second, a global sensitivity approach based on high dimensional model representations (HDMR) has been applied in order to identify those reactions which make the largest contributions to the overall uncertainty of the simulated results. The HDMR analysis has been restricted to the most important

  10. Use and Application of the ARCON96 Dispersion Model at the Y-12 Complex

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.A.; Lee, D.W.; Miller, R.L.

    2001-06-04

    The Atmospheric Relative Concentrations in Building Wakes computer code (ARCON96) was developed for the U.S. Nuclear Regulatory Commission (NRC) to calculate normalized concentrations in plumes from nuclear power plants at control room air intakes in the vicinity of hypothetical accidental releases. ARCON96 implements a straight-line Gaussian dispersion model with dispersion coefficients that are modified to account for low-wind-speed meander and building wake effects. These two modifications to the dispersion coefficients were benchmarked and justified in the ARCON96 code documentation. The code calculates {chi}/Q values (normalized concentrations) consistent with the methodology defined in NRC Regulatory Guide (RG) 1.145, position 3. Based on recent U. S. Department of Energy (DOE) acceptance of NRC RG 1.145, position 3 methodology for performing accident dispersion analyses, BWXT Y-12 L.L.C. evaluated the potential use and application for performing dispersion analyses at the Y-12 Complex. Using site specific meteorology inputs, a generic analysis (assuming ground-level releases) was performed to develop site-wide normalized concentrations for various distances to be used in consequence screening analyses. Additionally, the results were compared to other dispersion analysis models for confirmation of the results.

  11. Sensitivity of wave-length dispersive x-ray fluorescence of atmospheric aerosols

    International Nuclear Information System (INIS)

    The possibilities of wave-length dispersive x-ray spectrometry for the elemental analysis of the inorganic fraction of atmospheric aerosols collected on filter materials were thoroughly investigated. Three filter-types, namely one cellulose filter (Whatman 41) and two membrane filters (Millipore AAWP, pore size 0.8 um and Nuclepore, pore size 0.4 um) were compared. In order to measure the Nuclepore filters in a reproducible geometry under vacuum condition, a number of minor technical modifications had to be applied to the Philips PW 1450 spectrometer. X-ray tubes with chromium, tungsten, or silver anticathodes were tested for their capabilities for excitation of the particulate material. To obtain a wide range of elements, whether by their K-x rays or by their L-x rays, the tungsten tube appeared to be the best compromise. Detection limits of typical atmospheric aerosols after a 24 hour sampling on Nuclepore filters with a dust load of less than 100 ug. cm-2, were derived for Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Sr (K-x rays), Cd, Sn, Sb, Ba and Pb

  12. Modeling for pollution dispersion and air quality 4.: the Gaussian model

    International Nuclear Information System (INIS)

    The Gaussian Model is the simulation model for atmospheric pollutant dispersion most used in practice, in particular for engineering applications; it has been the first model used in the United States to predict the impact of pollutant sources on air quality and for many years it has constituted the projecting instrument in environmental and territory planning; today it is still a very useful instrument, above all when the meteorological input data are not so abundant. In recent year, great efforts have been made to extend the original Gaussian model to different typologies of sources and to make it able to treat more detailed effects, as, for example, a complex terrain, the dry deposition, the gravity effect on heavy particulate matter and other microscale effects. In this work, the main characteristics of the Gaussian model and the equations which govern its description of the dispersion of air pollutants are discussed; moreover, the main used codices which implement Gaussian models which can be easily found in commerce or, sometimes, in the net, are briefly described

  13. Mathematical modeling of dispersion in single interface flow analysis

    International Nuclear Information System (INIS)

    This work describes the optimization of the recently proposed fluid management methodology single interface flow analysis (SIFA) using chemometrics modelling. The influence of the most important physical and hydrodynamic flow parameters of SIFA systems on the axial dispersion coefficients estimated with the axially dispersed plug-flow model, was evaluated with chemometrics linear (multivariate linear regression) and non-linear (simple multiplicative and feed-forward neural networks) models. A D-optimal experimental design built with three reaction coil properties (length, configuration and internal diameter), flow-cell volume and flow rate, was adopted to generate the experimental data. Bromocresol green was used as the dye solution and the analytical signals were monitored by spectrophotometric detection at 614 nm. Results demonstrate that, independent of the model type, the statistically relevant parameters were the reactor coil length and internal diameter and the flow rate. The linear and non-linear multiplicative models were able to estimate the axial dispersion coefficient with validation r2 = 0.86. Artificial neural networks estimated the same parameter with an increased accuracy (r2 = 0.93), demonstrating that relations between the physical parameters and the dispersion phenomena are highly non-linear. The analysis of the response surface control charts simulated with the developed models allowed the interpretation of the relationships between the physical parameters and the dispersion processes.

  14. Mathematical modeling of dispersion in single interface flow analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, S. Sofia M.; Marques, Karine L. [REQUIMTE, Servico de Quimica-Fisica, Faculdade de Farmacia, Universidade do Porto, Rua Anibal Cunha, 164, 4099-030 Porto (Portugal); Lopes, Joao A., E-mail: joaolopes@ff.up.pt [REQUIMTE, Servico de Quimica-Fisica, Faculdade de Farmacia, Universidade do Porto, Rua Anibal Cunha, 164, 4099-030 Porto (Portugal); Santos, Joao L.M.; Lima, Jose L.F.C. [REQUIMTE, Servico de Quimica-Fisica, Faculdade de Farmacia, Universidade do Porto, Rua Anibal Cunha, 164, 4099-030 Porto (Portugal)

    2010-03-24

    This work describes the optimization of the recently proposed fluid management methodology single interface flow analysis (SIFA) using chemometrics modelling. The influence of the most important physical and hydrodynamic flow parameters of SIFA systems on the axial dispersion coefficients estimated with the axially dispersed plug-flow model, was evaluated with chemometrics linear (multivariate linear regression) and non-linear (simple multiplicative and feed-forward neural networks) models. A D-optimal experimental design built with three reaction coil properties (length, configuration and internal diameter), flow-cell volume and flow rate, was adopted to generate the experimental data. Bromocresol green was used as the dye solution and the analytical signals were monitored by spectrophotometric detection at 614 nm. Results demonstrate that, independent of the model type, the statistically relevant parameters were the reactor coil length and internal diameter and the flow rate. The linear and non-linear multiplicative models were able to estimate the axial dispersion coefficient with validation r{sup 2} = 0.86. Artificial neural networks estimated the same parameter with an increased accuracy (r{sup 2} = 0.93), demonstrating that relations between the physical parameters and the dispersion phenomena are highly non-linear. The analysis of the response surface control charts simulated with the developed models allowed the interpretation of the relationships between the physical parameters and the dispersion processes.

  15. Modelling the dispersion energy for Van der Waals complexes

    International Nuclear Information System (INIS)

    Strictly ab initio calculations of the dispersion energy are unfeasible in practice but for the smallest systems. A sensible alternative is to model the dispersion contribution through a damped multipolar expansion. This thesis proposes to represent the dispersion energy by means of a non-empirical, atom-atom model using damping functions scaled from 'exact' results for one electron-one electron systems. We start by investigating the scalability of ab initio calculated damping functions for closed-shell atom-atom dimers. Ab initio scaling parameters are employed to assess the quality of the damping functions yielded by a predictor scheme based on the charge overlap between the interacting monomers. The investigation of the scaling properties is extended to atom-linear molecule systems, focusing on the dependence on orientation of the short-range dispersion energy and how to account for it using isotropic damping parameters. We study the possibilities of an 'atomic' (multicentre) representation of the dispersion energy, in contrast to the conventional 'molecular' (single-centre) picture, devising a well-defined method to obtain 'atomic' dispersion coefficients from the computed molecular ones, as well as 'atomic' damping parameters. In all the studied cases, the 'atomic' approach describes more adequately the anisotropy of the interaction, through a localisation process of the charge overlap effects. The CO2/CO case, in particular, encourages to believe in the transferability of 'atomic' dispersion coefficients and damping parameters, which being confirmed by further work, the present results can be regarded as the basis of an universal and affordable model to estimate the dispersion contribution in intermolecular potentials. (author)

  16. Regional forecasting with global atmospheric models

    International Nuclear Information System (INIS)

    The scope of the report is to present the results of the fourth year's work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals

  17. A model for long-distance dispersal of boll weevils (Coleoptera: Curculionidae)

    Science.gov (United States)

    Westbrook, John K.; Eyster, Ritchie S.; Allen, Charles T.

    2011-07-01

    The boll weevil, Anthonomus grandis (Boheman), has been a major insect pest of cotton production in the US, accounting for yield losses and control costs on the order of several billion US dollars since the introduction of the pest in 1892. Boll weevil eradication programs have eliminated reproducing populations in nearly 94%, and progressed toward eradication within the remaining 6%, of cotton production areas. However, the ability of weevils to disperse and reinfest eradicated zones threatens to undermine the previous investment toward eradication of this pest. In this study, the HYSPLIT atmospheric dispersion model was used to simulate daily wind-aided dispersal of weevils from the Lower Rio Grande Valley (LRGV) of southern Texas and northeastern Mexico. Simulated weevil dispersal was compared with weekly capture of weevils in pheromone traps along highway trap lines between the LRGV and the South Texas / Winter Garden zone of the Texas Boll Weevil Eradication Program. A logistic regression model was fit to the probability of capturing at least one weevil in individual pheromone traps relative to specific values of simulated weevil dispersal, which resulted in 60.4% concordance, 21.3% discordance, and 18.3% ties in estimating captures and non-captures. During the first full year of active eradication with widespread insecticide applications in 2006, the dispersal model accurately estimated 71.8%, erroneously estimated 12.5%, and tied 15.7% of capture and non-capture events. Model simulations provide a temporal risk assessment over large areas of weevil reinfestation resulting from dispersal by prevailing winds. Eradication program managers can use the model risk assessment information to effectively schedule and target enhanced trapping, crop scouting, and insecticide applications.

  18. Atmospheric radionuclide transport model with radon postprocessor and SBG module. Model description version 2.8.0

    International Nuclear Information System (INIS)

    The study on the atmospheric radionuclide transport model with radon postprocessor and SBG module (model description version 2.8.0) covers the following issues: determination of emissions, radioactive decay, atmospheric dispersion calculation for radioactive gases, atmospheric dispersion calculation for radioactive dusts, determination of the gamma cloud radiation (gamma submersion), terrain roughness, effective source height, calculation area and model points, geographic reference systems and coordinate transformations, meteorological data, use of invalid meteorological data sets, consideration of statistical uncertainties, consideration of housings, consideration of bumpiness, consideration of terrain roughness, use of frequency distributions of the hourly dispersion situation, consideration of the vegetation period (summer), the radon post processor radon.exe, the SBG module, modeling of wind fields, shading settings.

  19. Users of middle atmosphere models remarks

    Science.gov (United States)

    Gamble, Joe

    1987-01-01

    The procedure followed for shuttle operations is to calculate descent trajectories for each potential shuttle landing site using the Global Reference Atmosphere Model (GRAM) to interactively compute density along the flight path 100 times to bound the statistics. The purpose is to analyze the flight dynamics, along with calculations of heat loads during reentry. The analysis program makes use of the modified version of the Jacchia-70 atmosphere, which includes He bulges over the poles and seasonal latitude variations at lower altitudes. For the troposphere, the 4-D Model is used up to 20 km, Groves from 30 km up to 90 km. It is extrapolated over the globe and faired into the Jacchia atmosphere between 90 and 115 km. Since data on the Southern Hemisphere was lacking, what was done was that the data was flipped over and lagged 6 months. Sometimes when winds are calculated from pressure data in the model there appear to be discontinuities. Modelers indicated that the GRAM was not designed to produce winds, but good wind data is needed for the landing phase of shuttle operations. Use of atmospheric models during reentry is one application where it is obvious that a single integrated atmosphere model is required.

  20. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

    Science.gov (United States)

    Stohl, A.; Seibert, P.; Wotawa, G.; Arnold, D.; Burkhart, J. F.; Eckhardt, S.; Tapia, C.; Vargas, A.; Yasunari, T. J.

    2012-04-01

    This presentation will show the results of a paper currently under review in ACPD and some additional new results, including more data and with an independent box modeling approach to support some of the findings of the ACPD paper. On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant (FD-NPP) developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined the first guess with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 16.7 (uncertainty range 13.4-20.0) EBq, which is the largest radioactive noble gas release in history not associated with nuclear bomb testing. There is strong evidence that the first strong 133Xe release started early, before active venting was performed. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. For 137Cs, the inversion results give a total emission of 35.8 (23.3-50.1) PBq, or about 42% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14-15 March but were generally high from 12 until 19 March, when they

  1. FIREPLUME model for plume dispersion from fires: Application to uranium hexafluoride cylinder fires

    International Nuclear Information System (INIS)

    This report provides basic documentation of the FIREPLUME model and discusses its application to the prediction of health impacts resulting from releases of uranium hexafluoride (UF6) in fires. The model application outlined in this report was conducted for the Draft Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted UF6. The FIREPLUME model is an advanced stochastic model for atmospheric plume dispersion that predicts the downwind consequences of a release of toxic materials from an explosion or a fire. The model is based on the nonbuoyant atmospheric dispersion model MCLDM (Monte Carlo Lagrangian Dispersion Model), which has been shown to be consistent with available laboratory and field data. The inclusion of buoyancy and the addition of a postprocessor to evaluate time-varying concentrations lead to the current model. The FIREPLUME model, as applied to fire-related UF6 cylinder releases, accounts for three phases of release and dispersion. The first phase of release involves the hydraulic rupture of the cylinder due to heating of the UF6 in the fire. The second phase involves the emission of material into the burning fire, and the third phase involves the emission of material after the fire has died during the cool-down period. The model predicts the downwind concentration of the material as a function of time at any point downwind at or above the ground. All together, five fire-related release scenarios are examined in this report. For each scenario, downwind concentrations of the UF6 reaction products, uranyl fluoride and hydrogen fluoride, are provided for two meteorological conditions: (1) D stability with a 4-m/s wind speed, and (2) F stability with a 1-m/s wind speed

  2. Computer Models Simulate Fine Particle Dispersion

    Science.gov (United States)

    2010-01-01

    Through a NASA Seed Fund partnership with DEM Solutions Inc., of Lebanon, New Hampshire, scientists at Kennedy Space Center refined existing software to study the electrostatic phenomena of granular and bulk materials as they apply to planetary surfaces. The software, EDEM, allows users to import particles and obtain accurate representations of their shapes for modeling purposes, such as simulating bulk solids behavior, and was enhanced to be able to more accurately model fine, abrasive, cohesive particles. These new EDEM capabilities can be applied in many industries unrelated to space exploration and have been adopted by several prominent U.S. companies, including John Deere, Pfizer, and Procter & Gamble.

  3. Analytical dispersion model for the chain of primary and secondary air pollutants released from point source

    Science.gov (United States)

    Juodis, Laurynas; Filistovič, Vitold; Maceika, Evaldas; Remeikis, Vidmantas

    2016-03-01

    An analytical model for dispersion of air pollutants released from a point source forming a secondary pollutant (e.g. chemical transformation or parent-daughter radionuclide chain) is formulated considering the constant wind speed and eddy diffusivities as an explicit function of downwind distance from the source in Cauchy (reflection-deposition type) boundary conditions. The dispersion of pollutants has been investigated by using the Gaussian plume dispersion parameters σy and σz instead of the diffusivity parameters Ky and Kz. For primary pollutant it was proposed to use the derived dry deposition factor instead of the source depletion alternative. An analytical solution for steady-state two-dimensional pollutant transport in the atmosphere is presented. Derived formulas include dependency from effective release height, gravitational and dry deposition velocities of primary and secondary pollutants, advection, surface roughness length and empirical dispersion parameters σy and σz. Demonstration of analytical solution application is provided by calculation of 135Xe and 135C air activity concentrations and the applicability of the model for the solution of atmospheric pollution transport problems.

  4. Stellar model atmospheres with magnetic line blanketing

    CERN Document Server

    Kochukhov, O; Shulyak, D

    2004-01-01

    Model atmospheres of A and B stars are computed taking into account magnetic line blanketing. These calculations are based on the new stellar model atmosphere code LLModels which implements direct treatment of the opacities due to the bound-bound transitions and ensures an accurate and detailed description of the line absorption. The anomalous Zeeman effect was calculated for the field strengths between 1 and 40 kG and a field vector perpendicular to the line of sight. The model structure, high-resolution energy distribution, photometric colors, metallic line spectra and the hydrogen Balmer line profiles are computed for magnetic stars with different metallicities and are discussed with respect to those of non-magnetic reference models. The magnetically enhanced line blanketing changes the atmospheric structure and leads to a redistribution of energy in the stellar spectrum. The most noticeable feature in the optical region is the appearance of the 5200 A depression. However, this effect is prominent only in ...

  5. New atmospheric model of Epsilon Eridani

    Science.gov (United States)

    Vieytes, Mariela; Fontenla, Juan; Buccino, Andrea; Mauas, Pablo

    2016-05-01

    We present a new semi-empirical model of the atmosphere of the widely studied K-dwarf Epsilon Eridani (HD 22049). The model is build to reproduce the visible spectral observations from 3800 to 6800 Angstrom and the h and k Mg II lines profiles. The computations were carried out using the Solar-Stellar Radiation Physical Modeling (SSRPM) tools, which calculate non-LTE population for the most important species in the stellar atmosphere. We show a comparison between the synthetic and observed spectrum, obtaining a good agreement in all the studied spectral range.

  6. Evaluation of the WIND System atmospheric models: An analytic approach

    International Nuclear Information System (INIS)

    An analytic approach was used in this study to test the logic, coding, and the theoretical limits of the WIND System atmospheric models for the Savannah River Plant. In this method, dose or concentration estimates predicted by the models were compared to the analytic solutions to evaluate their performance. The results from AREA EVACUATION and PLTFF/PLUME were very nearly identical to the analytic solutions they are based on and the evaluation procedure demonstrated that these models were able to reproduce the theoretical characteristics of a puff or a plume. The dose or concentration predicted by PLTFF/PLUME was always within 1% of the analytic solution. Differences between the dose predicted by 2DPUF and its analytic solution were substantially greater than those associated with PUFF/PLUME, but were usually smaller than 6%. This behavior was expected because PUFF/PLUME solves a form of the analytic solution for a single puff, and 2DPUF performs an integration over a period of time for several puffs to obtain the dose. Relatively large differences between the dose predicted by 2DPUF and its analytic solution were found to occur close to the source under stable atmospheric conditions. WIND System users should be aware of these situations in which the assumptions of the System atmospheric models may be violated so that dose predictions can be interpreted correctly. The WIND System atmospheric models are similar to many other dispersion codes used by the EPA, NRC, and DOE. If the quality of the source term and meteorological data is high, relatively accurate and timely forecasts for emergency response situations can be made by the WIND System atmospheric models

  7. Mathematical modeling of disperse two-phase flows

    CERN Document Server

    Morel, Christophe

    2015-01-01

    This book develops the theoretical foundations of disperse two-phase flows, which are characterized by the existence of bubbles, droplets or solid particles finely dispersed in a carrier fluid, which can be a liquid or a gas. Chapters clarify many difficult subjects, including modeling of the interfacial area concentration. Basic knowledge of the subjects treated in this book is essential to practitioners of Computational Fluid Dynamics for two-phase flows in a variety of industrial and environmental settings. The author provides a complete derivation of the basic equations, followed by more advanced subjects like turbulence equations for the two phases (continuous and disperse) and multi-size particulate flow modeling. As well as theoretical material, readers will discover chapters concerned with closure relations and numerical issues. Many physical models are presented, covering key subjects including heat and mass transfers between phases, interfacial forces and fluid particles coalescence and breakup, a...

  8. Statistics of Absolute and Relative Dispersion in the Atmospheric Convective Boundary Layer: A Large-Eddy Simulation Study

    NARCIS (Netherlands)

    Dosio, A.; Vilà-Guerau de Arellano, J.

    2006-01-01

    The influence of the different scales of turbulent motion on plume dispersion in the atmospheric convective boundary layer (CBL) is studied by means of a large-eddy simulation (LES). In particular, the large-scale (meandering) and small-scale (relative diffusion) contributions are separated by analy

  9. Nonsmooth feedback controls of nonlocal dispersal models

    Science.gov (United States)

    Malaguti, Luisa; Rubbioni, Paola

    2016-03-01

    The paper deals with a nonlocal diffusion equation which is a model for biological invasion and disease spread. A nonsmooth feedback control term is included and the existence of controlled dynamics is proved, satisfying different kinds of nonlocal condition. Jump discontinuities appear in the process. The existence of optimal control strategies is also shown, under suitably regular control functionals. The investigation makes use of techniques of multivalued analysis and is based on the degree theory for condensing operators in Hilbert spaces.

  10. Investigation Of Compressor Heat Dispersion Model

    OpenAIRE

    Shi, Da; Tao, Hong; Yang, Min

    2014-01-01

    This paper represents a method for calculate the heat dissipation capacity and discharge temperature for rotary compressors. The proposed heat dissipation model is used for calculating heat dissipating capacity of compressor in forced-convection/natural-convection and radiation heat transfer mode. The comparison between calculated result and experimental result for both constant speed compressors and variable speed compressors shows that the average heat dissipating capacity error is below 20...

  11. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2011-10-01

    Full Text Available On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant (FD-NPP developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions of two isotopes, the noble gas xenon-133 (133Xe and the aerosol-bound caesium-137 (137Cs, which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined the first guess with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 16.7 (uncertainty range 13.4–20.0 EBq, which is the largest radioactive noble gas release in history not associated with nuclear bomb testing. There is strong evidence that the first strong 133Xe release started very early, possibly immediately after the earthquake and the emergency shutdown on 11 March at 06:00 UTC. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. For 137Cs, the inversion results give a total emission of 35.8 (23.3–50.1 PBq, or about 42% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14–15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude exactly when spraying of

  12. Electrokinetic induced solute dispersion in porous media; pore network modeling

    Science.gov (United States)

    Li, Shuai; Schotting, Ruud; Raoof, Amir

    2013-04-01

    Electrokinetic flow plays an important role in remediation process, separation technique, and chromatography. The solute dispersion is a key parameter to determine transport efficiency. In this study, we present the electrokinetic effects on solute dispersion in porous media at the pore scale, using a pore network model. The analytical solution of the electrokinetic coupling coefficient was obtained to quantity the fluid flow velocity in a cylinder capillary. The effect of electrical double layer on the electrokinetic coupling coefficient was investigated by applying different ionic concentration. By averaging the velocity over cross section within a single pore, the average flux was obtained. Applying such single pore relationships, in the thin electrical double layer limit, to each and every pore within the pore network, potential distribution and the induced fluid flow was calculated for the whole domain. The resulting pore velocities were used to simulate solute transport within the pore network. By averaging the results, we obtained the breakthrough curve (BTC) of the average concentration at the outlet of the pore network. Optimizing the solution of continuum scale advection-dispersion equation to such a BTC, solute dispersion coefficient was estimated. We have compared the dispersion caused by electrokinetic flow and pure pressure driven flow under different Peclet number values. In addition, the effect of microstructure and topological properties of porous media on fluid flow and solute dispersion is presented, mainly based on different pore coordination numbers.

  13. Coupled atmosphere-wildland fire modelling

    Directory of Open Access Journals (Sweden)

    Jacques Henri Balbi

    2009-10-01

    Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.

  14. Updating Ontario's air dispersion models : a discussion paper

    International Nuclear Information System (INIS)

    This paper described air dispersion models and technical information relating to Ontario Regulation 346 under the Environmental Protection Act. The Ontario Ministry of the Environment plans to phase out existing air dispersion models and replace them with a series of models from the United States Environmental Protection Agency (in particular AERMOD and ISC-PRIME). However, before adopting the widespread use of the new models in Ontario, the Ministry is undergoing consultation with stakeholders. The Ministry's most recent initiatives in the development of better air quality standards have included the use of the latest scientific information to develop protective, effects-based air standards and the development of a risk management framework to implement the new standards while allowing for time, technology and economic issues to be considered. An update of Regulation 346 air dispersion models ensures that the latest scientific tools are being used to asses compliance with air standards. This will promote the use of the most modern scientific tools available to assess compliance with air quality standards. The major advantage of introducing new air dispersion models is the ability to use effects-based standards with appropriate averaging times to assess compliance. This makes it possible to better assess the health and environmental impacts from air emissions. 3 tabs., 3 figs

  15. Description of the RIVM/KNMI PUFF dispersion model

    OpenAIRE

    Verver GHL; de Leeuw FAAM; van Rheineck Leyssius HJ

    1990-01-01

    In this report an atmospheric transport model (the RIVM/KNMI PUFF- model) is described. The model is intended for operational use at KNMI and RIVM in case of an accidental release of (toxic or radioactive) gases or particles into the atmosphere. In its operational version the model area will cover most of Europe. The main processes accounted for in the model are: relative diffusion by wind shear and turbulence, advection as a function of space and time, the diurnal cycle of boundary layer hei...

  16. An Empirical Model of Wage Dispersion with Sorting

    DEFF Research Database (Denmark)

    Bagger, Jesper; Lentz, Rasmus

    This paper studies wage dispersion in an equilibrium on-the-job-search model with endogenous search intensity. Workers differ in their permanent skill level and firms differ with respect to productivity. Positive (negative) sorting results if the match production function is supermodular (submodu......This paper studies wage dispersion in an equilibrium on-the-job-search model with endogenous search intensity. Workers differ in their permanent skill level and firms differ with respect to productivity. Positive (negative) sorting results if the match production function is supermodular...... dispersion. We decompose wage variation into four sources: Worker heterogeneity, firm heterogeneity, frictions, and sorting. Worker heterogeneity contributes 51% of the variation, firm heterogeneity contributes 11%, frictions 23%, and finally sorting contributes 15%. We measure the output loss due to...

  17. Atmospheric neutrino flux calculation using the NRLMSISE00 atmospheric model

    CERN Document Server

    Honda, M; Kajita, T; Kasahara, K; Midorikawa, S

    2015-01-01

    In this paper, we extend the calculation of the atmospheric neutrino flux~\\cite{hkkm2004,hkkms2006,hkkm2011} to the sites in polar and tropical regions. In our earliest full 3D-calculation~\\cite{hkkm2004}, we used DPMJET-III~\\cite{dpm} for the hadronic interaction model above 5~GeV, and NUCRIN~\\cite{nucrin} below 5~GeV. We modified DPMJET-III as in Ref.~\\cite{hkkms2006} to reproduce the experimental muon spectra better, mainly using the data observed by BESS group~\\cite{BESSTeVpHemu}. In a recent work~\\cite{hkkm2011}, we introduced JAM interaction model for the low energy hadronic interactions. JAM is a nuclear interaction model developed with PHITS (Particle and Heavy-Ion Transport code System)~\\cite{phits}. In Ref.~\\cite{hkkm2011}, we could reproduce the observed muon flux at the low energies at balloon altitude with DPMJET-III above 32 GeV and JAM below that better than the combination of DPMJET-III above 5~GeV and NUCRIN below that. Besides the interaction model, we have also improved the calculation sche...

  18. Dispersion Models to Forecast Traffic-related Emissions in Urban Areas

    Directory of Open Access Journals (Sweden)

    Davide Scannapieco

    2011-11-01

    Full Text Available Down the centuries, a direct link had been developed between increase in mobility and increase in wealth. On the other hand, air emission of greenhouse gases (GHG due to vehicles equipped with internal combustion engines can be regarded as a negative pressure over the environment. In the coming decades, road transport is likely to remain a significant contributor to air pollution in cities. Many urban trips cover distances of less than 6 km. Since the effectiveness of catalytic converters in the initial minutes of engine operation is small, the average emission per distance driven is very high in urban areas. Also, poorly maintained vehicles that lack exhaust aftertreatment systems are responsible for a major part of pollutant emissions. Therefore in urban areas, where higher concentrations of vehicles can be easily found, air pollution represents a critical issue, being it related with both environment and human health protection: in truth, research in recent decades consistently indicates the adverse effects of outdoor air pollution on human health, and the evidence points to air pollution stemming from transport as an important contributor to these effects. Several institutions (EEA, USEPA, etc. focused their interest in dispersion models because of their potential effectiveness to forecast atmospheric pollution. Furthermore, air micropollutants such as Polycyclic Aromatic Compounds (PAH and Metallic Trace Elements (MTE are traffic-related and although very low concentrations their dispersion is a serious issue. However, dispersion models are usefully implemented to better manage this estimation problem. Nonetheless, policy makers and land managers have to deal with model selection, taking into account that several dispersion models are available, each one of them focused on specific goals (e.g., wind transport of pollutants, land morphology implementation, evaluation of micropollutants transport, etc.; a further aspect to be considered is

  19. Portable University Model of the Atmosphere (PUMA)

    Energy Technology Data Exchange (ETDEWEB)

    Fraedrich, K.; Kirk, E.; Lunkeit, F. [Hamburg Univ. (Germany). Meteorologisches Inst.

    1998-10-01

    The Portable University Model of the Atmosphere (PUMA) is based on the Reading multi-level spectral model SGCM (Simple Global Circulation Model) described by Hoskins and Simmons (1975) and James and Gray (1986). Originally developed as a numerical prediction model, it was changed to perform as a circulation model. For example, James and Gray (1986) studied the influence of surface friction on the circulation of a baroclinic atmosphere, James and James (1992), and James et al. (1994) investigated ultra-low-frequency variability, and Mole and James (1990) analyzed the baroclinic adjustment in the context of a zonally varying flow. Frisius et al. (1998) simulated an idealized storm track by embedding a dipole structure in a zonally symmetric forcing field and Lunkeit et al. (1998) investigated the sensitivity of GCM (General Circulation Model) scenarios by an adaption technique applicapable to SGCMs. (orig.)

  20. Atmospheric Reentry Dispersion Correction Ascent Phase Guidance for a Generic Reentry Vehicle

    Directory of Open Access Journals (Sweden)

    Avinash Chander

    2013-05-01

    Full Text Available Launch vehicle explicit guidance mechanism depends on the estimation of the desired burnout conditions and driving the vehicle to achieve these conditions. The accuracy of the vehicle at the target point depends on how tightly these conditions are achieved and what is the strategy used to define the trajectory. It has been observed inthe literature that most of the guidance mechanisms during reentry use vacuum guidance equations that is durin greentry the atmospheric effects are not considered. In order to achieve minimum miss distance at the target point theat mospheric effects are to be considered during the guided phase and appropriate corrections should be executed,otherwise depending on the reentry flight path angle and ballistic coefficient the errors can be as high as tens of nautical miles. In this paper, the authors develop a novel approach to these vacuum guided launch vehicle problems.The paper elaborates how to calculate a prior the reentry dispersion during the ascent phase guidance and provide guidance corrections such that the terminal conditions are achieved with higher accuracy.Defence Science Journal, 2013, 63(3, pp.233-241, DOI:http://dx.doi.org/10.14429/dsj.63.3733

  1. APT - A computer program for the numerical solution of problems in atmospheric dispersion and some applications to nuclear safety

    International Nuclear Information System (INIS)

    APT (Atmospheric Pollution Transport) is a computer program for predicting the dispersal of plumes emanating from point or line sources in a two-dimensional turbulent boundary layer. The governing partial differential conservation equations are solved by means of a marching finite-difference procedure and by the incorporation of a second-order closure turbulence model, which includes allowance for anisotropy and thermal-stratification effects. The methods adopted are briefly described in this paper, as is the validation of the model by comparison with wind tunnel and open air data. APT has been written so as to allow various parameters, such as meteorological roughness length, upward heat flux from the ground and dry deposition velocity, to change as a function of the distance downwind of the source of the effluent. The relevance of these features to nuclear safety calculations is discussed and examples of practical interest are given. The circumstances in which it is desirable to use APT in preference to the conventional Gaussian model are also described

  2. Coupling approaches used in atmospheric entry models

    Science.gov (United States)

    Gritsevich, M. I.

    2012-09-01

    While a planet orbits the Sun, it is subject to impact by smaller objects, ranging from tiny dust particles and space debris to much larger asteroids and comets. Such collisions have taken place frequently over geological time and played an important role in the evolution of planets and the development of life on the Earth. Though the search for near-Earth objects addresses one of the main points of the Asteroid and Comet Hazard, one should not underestimate the useful information to be gleaned from smaller atmospheric encounters, known as meteors or fireballs. Not only do these events help determine the linkages between meteorites and their parent bodies; due to their relative regularity they provide a good statistical basis for analysis. For successful cases with found meteorites, the detailed atmospheric path record is an excellent tool to test and improve existing entry models assuring the robustness of their implementation. There are many more important scientific questions meteoroids help us to answer, among them: Where do these objects come from, what are their origins, physical properties and chemical composition? What are the shapes and bulk densities of the space objects which fully ablate in an atmosphere and do not reach the planetary surface? Which values are directly measured and which are initially assumed as input to various models? How to couple both fragmentation and ablation effects in the model, taking real size distribution of fragments into account? How to specify and speed up the recovery of a recently fallen meteorites, not letting weathering to affect samples too much? How big is the pre-atmospheric projectile to terminal body ratio in terms of their mass/volume? Which exact parameters beside initial mass define this ratio? More generally, how entering object affects Earth's atmosphere and (if applicable) Earth's surface? How to predict these impact consequences based on atmospheric trajectory data? How to describe atmospheric entry

  3. Radiation environment models and the atmospheric cutoff

    Science.gov (United States)

    Konradi, Andrei; Hardy, Alva C.; Atwell, William

    1987-01-01

    The limitations of radiation environment models are examined by applying the model to the South Atlantic anomaly (SAA). The local magnetic-field-intensity (in gauss) and McIlwain (1961) drift-shell-parameter contours in the SAA are analyzed. It is noted that it is necessary to decouple the atmospheric absorption effects from the trapped radiation models in order to obtain accurate radiation dose predictions. Two methods for obtaining more accurate results are proposed.

  4. Dispersion of the impurity released from an instantaneous source in turbulent atmosphere

    Science.gov (United States)

    Balin, Yuri S.; Ershov, Arkadii D.; Bril, Andrey I.; Kabashnikov, Vitaliy P.; Popov, V. M.; Chaikovsky, Anatoly P.

    2002-02-01

    The results of comprehensive field experiment are presented. The objective of the experiment is lidar technique development for control of pollutant dispersion from pulse source. Experiment was carried out in steppe region, underlying surface was covered with sparse vegetation. Charge exploded at the altitude of 10 m stand for source of pollutant. Lidar was used to trace the cloud of explosion products. The ratio of backscatter signal from the cloud to aerosol background signal was recorded along with the time and coordinates of sounded points. Ultrasonic meteorological station and sodar 25 - 30 meters distant from explosion location were used to measure air temperature, vertical and horizontal components of wind velocity and its direction, total energy of turbulent motions, tangential turbulent friction stress and vertical turbulent heat flow. Experimental data were compared with the results of numerical modeling of pollutant spatial distribution performed on the basis of Gaussian statistical model. Numerical results were primarily in satisfactory agreement with experimental data.

  5. The environmental radiological atmospheric impact modelling system (ERAIMS) at ANSTO, Lucas Heights

    International Nuclear Information System (INIS)

    Decision-makers managing the emergency response to an actual or potential release of airborne radionuclides from the Lucas Heights Science and Technology Centre (LHSTC) require real-time estimates of the trajectory and dispersion of any released radionuclides. Complex terrain surrounding the LHSTC has an impact on the downwind trajectory and atmospheric dispersion of released radionuclides. Under certain atmospheric conditions, the released cloud could be transported into the valley without direct impact on the nearest population. This entrapment in the steep sided, narrow valley, might mean that the cloud could remain more concentrated and cause impacts on more distant receptor populations down the valley. Alternatively, the cloud could disperse directly across the valley to the nearest residential population without any significant entrainment into, or impact, on the valley. The Environmental Radiological Atmospheric Impact Modelling System (ERAIMS) is a realtime response model which has been developed for the LHSTC. It estimates downwind impacts based on a pre-set source term, prevailing meteorological conditions which are measured every 15 minutes, receptor characteristics and exposure pathways. This paper describes the total system, from collection and calibration of meteorological data, to the running of the models in the ANSTO emergency response facility and display of data for controllers of any emergency. The current assessment of different atmospheric dispersion models available for use in this facility will also be discussed in terms of atmospheric tracer studies conducted in the region and International Best Practice. Copyright (2000) Australasian Radiation Protection Society Inc

  6. A numerical three-dimensional ocean general circulation and radionuclides dispersion model

    International Nuclear Information System (INIS)

    The dispersion of radioactive waste disposed of in the deep-sea or transferred from the atmosphere is a complex hydrodynamic problem concerned by space scales as large as the world ocean. The recent development in the high-speed computers has led to significant progress in ocean modelling and now allows a thorough improvement in the accuracy of the simulations of the nuclides dispersion in the sea. A three-dimensional ocean general circulation model has been recently developed in France for research and engineering purposes. The model solves the primitive equation of the ocean hydrodynamics and the advection-diffusion equation for any dissolved tracer. The code has been fully vectorized and multitasked on 1 to 4 processors of the CRAY-2

  7. Fuel dispersal modeling for aircraft-runway impact scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Tieszen, S.R.

    1995-11-01

    A fuel dispersal model for C-141 transport accidents was developed for the Defense Nuclear Agency`s Fuel Fire Technology Base Program to support Weapon System Safety Assessments. The spectrum of accidents resulting from aircraft impact on a runway was divided into three fuel dispersal regimes: low, intermediate, and high-velocity impact. Sufficient data existed in the accident, crash test, and fuel-filled bomb literature to support development of a qualitative framework for dispersal models, but not quantitative models for all regimes. Therefore, a test series at intermediate scale was conducted to generate data on which to base the model for the high-velocity regime. Tests were conducted over an impact velocity range from 12 m/s to 91 m/s and angles of impact from 22.5{degrees} to 67.5{degrees}. Dependent variables were area covered by dispersed fuel, amount of mass in that area, and location of the area relative to the impact line. Test results showed that no liquid pooling occurred for impact velocities greater than 61 m/s, independent of the angle of impact. Some pooling did occur at lower velocities, but in no test was the liquid-layer thickness greater than 5.25 mm.

  8. Transverse nonlinear instability for two-dimensional dispersive models

    OpenAIRE

    Rousset, F.; N. Tzvetkov

    2006-01-01

    We present a method to prove nonlinear instability of solitary waves in dispersive models. Two examples are analyzed: we prove the nonlinear long time instability of the KdV solitary wave (with respect to periodic transverse perturbations) under a KP-I flow and the transverse nonlinear instability of solitary waves for the cubic nonlinear Schr\\"odinger equation.

  9. PHYSICAL AND NUMERICAL MODELING OF ASD EXHAUST DISPERSION AROUND HOUSES

    Science.gov (United States)

    The report discusses the use of a wind tunnel to physically model the dispersion of exhaust plumes from active soil depressurization (ASD) radon mitigation systems in houses. he testing studied the effects of exhaust location (grade level vs. above the eave), as house height, roo...

  10. Development of regional atmospheric dynamic and air pollution models for nuclear emergency response system WSPEEDI

    International Nuclear Information System (INIS)

    WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information) is a computer-based emergency response system to predict long-range atmospheric dispersion of radionuclides discharged into the atmosphere due to a nuclear accident. WSPEEDI has been applied to several international exercises and real events. Through such experiences, the new version of WSPEEDI aims to employ a combination of an atmospheric dynamic model and a particle random walk model for more accurate predictions. This paper describes these models, improvement of prediction and computational techniques for quick responses. (author)

  11. CFD modeling of dust dispersion through Najaf historic city centre

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2014-01-01

    Full Text Available The aim of this project is to study the influences of the wind flow and dust particles dispersion through Najaf historic city centre. Two phase Computational Fluid Dynamics (CFD model using a Reynolds Average Navier Stokes (RANS equations has been used to simulate the wind flow and the transport and dispersion of the dust particles through the historic city centre. This work may provide useful insight to urban designers and planners interested in examining the variation of city breathability as a local dynamic morphological parameter with the local building packing density.

  12. Exposure estimates using urban plume dispersion and traffic microsimulation models

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.J.; Mueller, C.; Bush, B.; Stretz, P.

    1997-12-01

    The goal of this research effort was to demonstrate a capability for analyzing emergency response issues resulting from accidental or mediated airborne toxic releases in an urban setting. In the first year of the program, the authors linked a system of fluid dynamics, plume dispersion, and vehicle transportation models developed at Los Alamos National Laboratory to study the dispersion of a plume in an urban setting and the resulting exposures to vehicle traffic. This research is part of a larger laboratory-directed research and development project for studying the relationships between urban infrastructure elements and natural systems.

  13. Sulfur dioxide estimations in the planetary boundary layer using dispersion models and satellite retrievals

    Science.gov (United States)

    Zarauz, Jorge V.

    The health and environmental conditions in the Central Andes city La Oroya, Peru, have been seriously damaged by the heavy metal mining activities in the region. The situation has been exacerbated by the complex topography, which prevents proper mixing and dissolution of particles and gases released into the atmosphere. Understanding how pollutants are dispersed in populated regions, especially in complex terrain, would help to create mitigation strategies. The present study uses CALPUFF and HYSPLIT dispersion/deposition models to estimate sulfur dioxide (SO2) dispersion from the main stack of the La Oroya metallurgical plant. Due to the lack of meteorological data in the area, the Weather Research and Forecasting model (WRF) is used with observational nudging for temperature, relative humidity, and wind fields of three surface meteorological stations specifically installed for the study. The pollutant dispersion models are sensitive to a precise estimation of the turbulent vertical transport of mass, energy and moisture in the low atmosphere; therefore, two planetary boundary layer (PBL) schemes are tested, the Mellor-Yamada-Janjic and Yonsei University models. The dispersion models are run and results compared with field measurements at La Oroya, and Huancayo. The observation-nudging and YSU scheme considerably improved the prognostic variables. CALPUFF and HYSPLIT models showed similar patterns; however, HYSPLIT overestimated SO2 concentrations for low PBLs. Moreover, recent enhancements on spectral, spatial and temporal resolution of atmospheric scanning sensors of chemical constituents from the space, have led to detecting trace gases of anthropogenic origin in the lower troposphere. This contribution also explores the SO2 level 2 dataset from Ozone Mapping Instrument (OMI), in conjunction with atmospheric optical depth and Angstrom coefficient data products, extracted from MODerate Resolution Imaging Spectroradiometer (MODIS) to estimate SO2 loads in the PBL

  14. Validation data for models of contaminant dispersal : scaling laws and data needs.

    Energy Technology Data Exchange (ETDEWEB)

    O' Hern, Timothy John; Ceccio, Steven Louis (University of Michigan, Ann Arbor, MI)

    2004-09-01

    Contaminant dispersal models for use at scales ranging from meters to miles are widely used for planning sensor locations, first-responder actions for release scenarios, etc. and are constantly being improved. Applications range from urban contaminant dispersal to locating buried targets from an exhaust signature. However, these models need detailed data for model improvement and validation. A small Sandia National Laboratories Laboratory Directed Research and Development (LDRD) program was funded in FY04 to examine the feasibility and usefulness of a scale-model capability for quantitative characterization of flow and contaminant dispersal in complex environments. This report summarizes the work performed in that LDRD. The basics of atmospheric dispersion and dispersion modeling are reviewed. We examine the need for model scale data, and the capability of existing model test methods. Currently, both full-scale and model scale experiments are performed in order to collect validation data for numerical models. Full-scale experiments are expensive, are difficult to repeat, and usually produce relatively sparse data fields. Model scale tests often employ wind tunnels, and the data collected is, in many cases, derived from single point measurements. We review the scaling assumptions and methods that are used to relate model and full scale flows. In particular, we examine how liquid flows may be used to examine the process of atmospheric dispersion. The scaling between liquid and gas flows is presented. Use of liquid as the test fluid has some advantages in terms of achieving fully turbulent Reynolds numbers and in seeding the flow with neutrally buoyant tracer particles. In general, using a liquid flow instead of a gas flow somewhat simplifies the use of full field diagnostics, such as Particle Image Velocimetry and Laser Induced Fluorescence. It is also possible to create stratified flows through mixtures of fluids (e.g., water, alcohol, and brine). Lastly, we

  15. ATMOSPHERIC HEALTH EFFECTS FRAMEWORK (AHEF) MODEL

    Science.gov (United States)

    The Atmospheric and Health Effects Framework (AHEF) is used to assess theglobal impacts of substitutes for ozone-depleting substances (ODS). The AHEF is a series of FORTRAN modeling modules that collectively form a simulation framework for (a) translating ODS production into emi...

  16. A linearized dispersion relation for orthorhombic pseudo-acoustic modeling

    KAUST Repository

    Song, Xiaolei

    2012-11-04

    Wavefield extrapolation in acoustic orthorhombic anisotropic media suffers from wave-mode coupling and stability limitations in the parameter range. We introduce a linearized form of the dispersion relation for acoustic orthorhombic media to model acoustic wavefields. We apply the lowrank approximation approach to handle the corresponding space-wavenumber mixed-domain operator. Numerical experiments show that the proposed wavefield extrapolator is accurate and practically free of dispersions. Further, there is no coupling of qSv and qP waves, because we use the analytical dispersion relation. No constraints on Thomsen\\'s parameters are required for stability. The linearized expression may provide useful application for parameter estimation in orthorhombic media.

  17. Puff models for simulation of fugitive radioactive emissions in atmosphere

    International Nuclear Information System (INIS)

    A puff model for the dispersion of material from fugitive radioactive emissions is presented. For vertical diffusion the model is based on general techniques for solving time dependent advection-diffusion equation: the ADMM (Advection Diffusion Multilayer Method) and GILTT (Generalized Integral Laplace Transform Technique) techniques. The first one is an analytical solution based on a discretization of the Atmospheric Boundary Layer (ABL) in sub-layers where the advection-diffusion equation is solved by the Laplace transform technique. The solution is given in integral form. The second one is a well-known hybrid method that had solved a wide class of direct and inverse problems mainly in the area of Heat Transfer and Fluid Mechanics and the solution is given in series form. Comparisons between values predicted by the models against experimental ground-level concentrations are shown. (author)

  18. PIV Measurements of Atmospheric Turbulence and Pollen Dispersal Above a Corn Canopy

    Science.gov (United States)

    Zhu, W.; van Hout, R.; Luznik, L.; Katz, J.

    2003-12-01

    Dispersal of pollen grains by wind and gravity (Anemophilous) is one of the oldest means of plant fertilization available in nature. Recently, the growth of genetically modified foods has raised questions on the range of pollen dispersal in order to limit cross-fertilization between organically grown and transgenic crops. The distance that a pollen grain can travel once released from the anther is determined, among others, by the aerodynamic parameters of the pollen and the characteristics of turbulence in the atmosphere in which it is released. Turbulence characteristics of the flow above a pollinating corn field were measured using Particle Image Velocimetry (PIV). The measurements were performed on the eastern shore of the Chesapeake Bay, in Maryland, during July 2003. Two PIV systems were used simultaneously, each with an overall sample area of 18x18 cm. The spacing between samples was about equal to the field of view. The PIV instrumentation, including CCD cameras, power supply and laser sheets forming optics were mounted on a measurement platform, consisting of a hydraulic telescopic arm that could be extended up to 10m. The whole system could be rotated in order to align it with the flow. The flow was seeded with smoke generated about 30m upstream of the sample areas. Measurements were carried out at several elevations, from just below canopy height up to 1m above canopy. The local meteorological conditions around the test site were monitored by other sensors including sonic anemometers, Rotorod pollen counters and temperature sensors. Each processed PIV image provides an instantaneous velocity distribution containing 64x64 vectors with a vector spacing of ~3mm. The pollen grains (~100mm) can be clearly distinguished from the smoke particles (~1mm) based on their size difference. The acquired PIV data enables calculation of the mean flow and turbulence characteristics including Reynolds stresses, spectra, turbulent kinetic energy and dissipation rate. Data

  19. Atmospheric statistical dynamic models. Model performance: the Lawrence Livermore Laboratoy Zonal Atmospheric Model

    International Nuclear Information System (INIS)

    Results from the zonal model indicate quite reasonable agreement with observation in terms of the parameters and processes that influence the radiation and energy balance calculations. The model produces zonal statistics similar to those from general circulation models, and has also been shown to produce similar responses in sensitivity studies. Further studies of model performance are planned, including: comparison with July data; comparison of temperature and moisture transport and wind fields for winter and summer months; and a tabulation of atmospheric energetics. Based on these preliminary performance studies, however, it appears that the zonal model can be used in conjunction with more complex models to help unravel the problems of understanding the processes governing present climate and climate change. As can be seen in the subsequent paper on model sensitivity studies, in addition to reduced cost of computation, the zonal model facilitates analysis of feedback mechanisms and simplifies analysis of the interactions between processes

  20. Fluctuation Theorem in an Atmospheric Circulation Model

    CERN Document Server

    Schalge, Bernd; Wouters, Jeroen; Fraedrich, Klaus; Lunkeit, Frank

    2012-01-01

    Evidence for the validity of the Fluctuation Theorem (FT) in an atmospheric Global Circulation Model is found. The model is hydrostatic with variable numbers of vertical levels and different horizontal resolutions. For finite time intervals the largest local Lyapunov exponent (LLLE) is found to be negative consistent with predictions of the FT. The effect is present for resolutions up to wave numbers l=42 (~ 250km) and 10 levels.

  1. Dispersion modeling of selected PAHs in urban air: A new approach combining dispersion model with GIS and passive air sampling

    Czech Academy of Sciences Publication Activity Database

    Sáňka, O.; Melymuk, L.; Čupr, P.; Dvorská, Alice; Klánová, J.

    2014-01-01

    Roč. 90, oct (2014), s. 88-95. ISSN 1352-2310 Institutional support: RVO:67179843 Keywords : passive air sampling * air dispersion modeling * GIS * polycyclic aromatic hydrocarbons * emission inventories Subject RIV: DI - Air Pollution ; Quality Impact factor: 3.281, year: 2014

  2. Comparison of turbulent particle dispersion models in turbulent shear flows

    Directory of Open Access Journals (Sweden)

    S. Laín

    2007-09-01

    Full Text Available This work compares the performance of two Lagrangian turbulent particle dispersion models: the standard model (e.g., that presented in Sommerfeld et al. (1993, in which the fluctuating fluid velocity experienced by the particle is composed of two components, one correlated with the previous time step and a second one randomly sampled from a Wiener process, and the model proposed by Minier and Peirano (2001, which is based on the PDF approach and performs closure at the level of acceleration of the fluid experienced by the particle. Formulation of a Langevin equation model for the increments of fluid velocity seen by the particle allows capturing some underlying physics of particle dispersion in general turbulent flows while keeping the mathematical manipulation of the stochastic model simple, thereby avoiding some pitfalls and simplifying the derivation of macroscopic relations. The performance of both dispersion models is tested in the configurations of grid-generated turbulence (Wells and Stock (1983 experiments, simple shear flow (Hyland et al., 1999 and confined axisymmetric jet flow laden with solids (Hishida and Maeda (1987 experiments.

  3. A virtual source model for building wake dispersion in nuclear safety calculations

    International Nuclear Information System (INIS)

    The suitability of a virtual source building wake dispersion model for use in estimating near field air concentrations of activity due to the atmospheric discharge of radionuclides from nuclear power stations is discussed. Simple prescriptions for the application of the model are developed and the model's predictions are compared with a limited amount of experimental data. The advantages and limitations of simple models in general and the virtual source model in particular are identified by comparing the assumptions inherent in simple models with the physical processes which govern air flows in building wakes. Finally, conclusions are drawn as to the range of applicability of the model, together with estimates of the model's predictive accuracy. (author)

  4. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    Directory of Open Access Journals (Sweden)

    J. Kukkonen

    2014-01-01

    Full Text Available We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with the data of two prescribed wild-land fire experiments. For the SCAR-C experiment in Quinault (US in 1994, the predicted vertical extents of the plume at maximum plume rise were between 500–800 m and 200–700 m, using two alternative meteorological datasets. The corresponding observed injection heights of the aerosol particles measured using an airborne LIDAR (LIght Detection And Ranging ranged from 250 and 600 m. For the prescribed burning experiment in Hyytiälä (Finland in 2009, the model predictions were compared with plume elevations and diameters, determined based on particulate matter number concentration measurements on board an aeroplane. The agreement of modelled and measured results was good, provided that one assumes the measured maximum convective heat fluxes as input data for the model. The results demonstrate that in field experiments on wild-land fires, there are substantial uncertainties in estimating both (i the source terms for the atmospheric dispersion computations, and (ii the relevant vertical meteorological profiles. The results provide more confidence that cross-plume integrated mathematical models, such as the BUOYANT model, can be used to fairly good accuracy for evaluating the dispersion from major wild-land fires.

  5. Effects of vertical shear in modelling horizontal oceanic dispersion

    Science.gov (United States)

    Lanotte, A. S.; Corrado, R.; Palatella, L.; Pizzigalli, C.; Schipa, I.; Santoleri, R.

    2016-02-01

    The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ˜ 1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

  6. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    Science.gov (United States)

    Kukkonen, J.; Nikmo, J.; Sofiev, M.; Riikonen, K.; Petäjä, T.; Virkkula, A.; Levula, J.; Schobesberger, S.; Webber, D. M.

    2014-11-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with the data of two prescribed wild-land fire experiments. For the SCAR-C experiment in Quinault (US) in 1994, the predicted vertical extents of the plume at maximum plume rise were between 500 and 800 m and between 200 and 700 m, using two alternative meteorological data sets. The corresponding observed injection heights of the aerosol particles measured using an airborne lidar (light detection and ranging) ranged from 250 to 600 m. For the prescribed burning experiment in Hyytiälä (Finland) in 2009, the model predictions were compared with plume elevations and diameters, determined based on particulate matter number concentration measurements onboard an aeroplane. However, the agreement between modelled and measured results substantially depends on how the properties of the source term are evaluated, especially regarding the convective heat fluxes from the fire. The results demonstrate that in field experiments on wild-land fires, there are substantial uncertainties in estimating both (i) the source terms for the atmospheric dispersion computations and (ii) the relevant vertical meteorological profiles.

  7. Measuring odours in the environment vs. dispersion modelling: A review

    Science.gov (United States)

    Capelli, Laura; Sironi, Selena; Del Rosso, Renato; Guillot, Jean-Michel

    2013-11-01

    Source characterization alone is not sufficient to account for the effective impact of odours on citizens, which would require to quantify odours directly at receptors. However, despite a certain simplicity of odour measurement at the emission source, odour measurement in the field is a quite more complicated task. This is one of the main reasons for the spreading of odour impact assessment approaches based on odour dispersion modelling. Currently, just a very limited number of reports discussing the use of tracer gas dispersion experiments both in the field and in wind tunnels for model validation purposes can be found in literature. However, when dealing with odour emissions, it is not always possible to identify a limited number of tracer compounds, nor to relate analytical concentrations to odour properties, thus giving that considering single odorous compounds might be insufficient to account for effective odour perception. For these reasons, the possibility of measuring of odours in the field, both as a way for directly assessing odour annoyance or for verifying that modelled odour concentrations correspond to the effective odour perception by humans, is still an important objective. The present work has the aim to review the techniques that can be adopted for measuring odours in the field, particularly discussing how such techniques can be used in alternative or in combination with odour dispersion models for odour impact assessment purposes, and how the results of field odour measurements and model outputs can be related and compared to each other.

  8. Network models of frugivory and seed dispersal: Challenges and opportunities

    Science.gov (United States)

    Carlo, Tomás A.; Yang, Suann

    2011-11-01

    Network analyses have emerged as a new tool to study frugivory and seed dispersal (FSD) mutualisms because networks can model and simplify the complexity of multiple community-wide species interactions. Moreover, network theory suggests that structural properties, such as the presence of highly generalist species, are linked to the stability of mutualistic communities. However, we still lack empirical validation of network model predictions. Here we outline new research avenues to connect network models to FSD processes, and illustrate the challenges and opportunities of this tool with a field study. We hypothesized that generalist frugivores would be important for forest stability by dispersing seeds into deforested areas and initiating reforestation. We then constructed a network of plant-frugivore interactions using published data and identified the most generalist frugivores. To test the importance of generalists we measured: 1) the frequency with which frugivores moved between pasture and forest, 2) the bird-generated seed rain under perches in the pasture, and 3) the perching frequency of birds above seed traps. The generalist frugivores in the forest network were not important for seed dispersal into pastures, and thus for forest recovery, because the forest network excluded habitat heterogeneities, frugivore behavior, and movements. More research is needed to develop ways to incorporate relevant FSD processes into network models in order for these models to be more useful to community ecology and conservation. The network framework can serve to spark and renew interest in FSD and further our understanding of plant-animal communities.

  9. Generalized uniform formulae for atmospheric dispersion of activities released from a ventilation stack or from a leaky reactor building

    International Nuclear Information System (INIS)

    Relations are given for the calculation of the atmospheric transport and dispersion of industrial gaseous wastes released from the stacks of factories, power plants and nuclear power plants. Modified formulae are derived for stack disposal from a small stack, also applicable in calculating the gaseous waste release from a leaky reactor. Uniform generalized formulae are presented serving the calculation of both high and short stack disposals as well as of reactor building leakages. (L.O.)

  10. Probabilistic Accident Consequence Uncertainty Analysis of the Atmospheric Dispersion and Deposition Module in the COSYMA Package (invited paper)

    International Nuclear Information System (INIS)

    The uncertainty analysis is described of the atmospheric dispersion and deposition module of COSYMA, describing both the methods of obtaining distributions on the input parameters and the results of the analysis. The uncertainty distributions on the input parameter values were obtained using formal techniques of expert judgement elicitation. The aim of the module analysis was to identify those parameters whose uncertainty makes major contributions to the overall uncertainty, and which should be included in the final analysis of the whole COSYMA system. (author)

  11. A Global Atmospheric Model of Meteoric Iron

    Science.gov (United States)

    Feng, Wuhu; Marsh, Daniel R.; Chipperfield, Martyn P.; Janches, Diego; Hoffner, Josef; Yi, Fan; Plane, John M. C.

    2013-01-01

    The first global model of meteoric iron in the atmosphere (WACCM-Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion-molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion-molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM-Fe model has been evaluated against a number of available ground-based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+ concentration compared with the limited rocket-borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe-molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1-D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.

  12. CFD Modeling of LNG Spill: Humidity Effect on Vapor Dispersion

    Science.gov (United States)

    Giannissi, S. G.; Venetsanos, A. G.; Markatos, N.

    2015-09-01

    The risks entailed by an accidental spill of Liquefied Natural Gas (LNG) should be indentified and evaluated, in order to design measures for prevention and mitigation in LNG terminals. For this purpose, simulations are considered a useful tool to study LNG spills and to understand the mechanisms that influence the vapor dispersion. In the present study, the ADREA-HF CFD code is employed to simulate the TEEX1 experiment. The experiment was carried out at the Brayton Fire Training Field, which is affiliated with the Texas A&M University system and involves LNG release and dispersion over water surface in open- obstructed environment. In the simulation the source was modeled as a two-phase jet enabling the prediction of both the vapor dispersion and the liquid pool spreading. The conservation equations for the mixture are solved along with the mass fraction for natural gas. Due to the low prevailing temperatures during the spill ambient humidity condenses and this might affect the vapor dispersion. This effect was examined in this work by solving an additional conservation equation for the water mass fraction. Two different models were tested: the hydrodynamic equilibrium model which assumes kinetic equilibrium between the phases and the non hydrodynamic equilibrium model, in order to assess the effect of slip velocity on the prediction. The slip velocity is defined as the difference between the liquid phase and the vapor phase and is calculated using the algebraic slip model. Constant droplet diameter of three different sizes and a lognormal distribution of the droplet diameter were applied and the results are discussed and compared with the measurements.

  13. Climate change and climate systems influence and control the atmospheric dispersion of desert dust: implications for human health

    Science.gov (United States)

    Griffin, Dale W.

    2010-01-01

    The global dispersion of desert dust through Earth’s atmosphere is greatly influenced by temperature. Temporal analyses of ice core data have demonstrated that enhanced dust dispersion occurs during glacial events. This is due to an increase in ice cover, which results in an increase in drier terrestrial cover. A shorter temporal analysis of dust dispersion data over the last 40 years has demonstrated an increase in dust transport. Climate systems or events such as the North Atlantic Oscillation, the Indian Ocean subtropical High, Pacific Decadal Oscillation, and El Nino-Sothern Oscillation are known to influence global short-term dust dispersion occurrence and transport routes. Anthropogenic influences on dust transport include deforestation, harmful use of topsoil for agriculture as observed during the American Dust Bowl period, and the creation of dry seas (Aral Sea) and lakes (Lake Owens in California and Lake Chad in North Africa) through the diversion of source waters (for irrigation and drinking water supplies). Constituents of desert dust both from source regions (pathogenic microorganisms, organic and inorganic toxins) and those scavenged through atmospheric transport (i.e., industrial and agricultural emissions) are known to directly impact human and ecosystem health. This presentation will present a review of global scale dust storms and how these events can be both a detriment and benefit to various organisms in downwind environments.

  14. Regional transport model of atmospheric sulfates

    International Nuclear Information System (INIS)

    As part of the Sulfate Regional Experiment (SURE) Design Project, a regional transport model of atmospheric sulfates has been developed. This quasi-Lagrangian three-dimensional grid numerical model uses a detailed SO2 emission inventory of major anthropogenic sources in the Eastern U.S. region, and observed meteorological data during an episode as inputs. The model accounts for advective transport and turbulent diffusion of the pollutants. The chemical transformation of SO2 and SO4/sup =/ and the deposition of the species at the earth's surface are assumed to be linear processes at specified constant rates. The numerical model can predict the daily average concentrations of SO2 and SO4/sup =/ at all receptor locations in the grid region during the episode. Because of the spatial resolution of the grid, this model is particularly suited to investigate the effect of tall stacks in reducing the ambient concentration levels of sulfur pollutants. This paper presents the formulations and assumptions of the regional sulfate transport model. The model inputs and results are discussed. Isopleths of predicted SO2 and SO4/sup =/ concentrations are compared with the observed ground level values. The bulk of the information in this paper is directed to air pollution meteorologists and environmental engineers interested in the atmospheric transport modeling studies of sulfur oxide pollutants

  15. Spatially-varying surface roughness and ground-level air quality in an operational dispersion model

    International Nuclear Information System (INIS)

    Urban form controls the overall aerodynamic roughness of a city, and hence plays a significant role in how air flow interacts with the urban landscape. This paper reports improved model performance resulting from the introduction of variable surface roughness in the operational air-quality model ADMS-Urban (v3.1). We then assess to what extent pollutant concentrations can be reduced solely through local reductions in roughness. The model results suggest that reducing surface roughness in a city centre can increase ground-level pollutant concentrations, both locally in the area of reduced roughness and downwind of that area. The unexpected simulation of increased ground-level pollutant concentrations implies that this type of modelling should be used with caution for urban planning and design studies looking at ventilation of pollution. We expect the results from this study to be relevant for all atmospheric dispersion models with urban-surface parameterisations based on roughness. -- Highlights: • Spatially variable roughness improved performance of an operational model. • Scenario modelling explored effect of reduced roughness on air pollution. • Reducing surface roughness can increase modelled ground-level pollution. • Damped vertical mixing outweighs increased horizontal advection in model study. • Result should hold for any model with a land-surface coupling based on roughness. -- Spatially varying roughness improves model simulations of urban air pollutant dispersion. Reducing roughness does not always decrease ground-level pollution concentrations

  16. Development of an advanced atmospheric/transport model for emergency response purposes

    International Nuclear Information System (INIS)

    Atmospheric transport and diffusion models have been developed for real-time calculations of the location and concentration of toxic or radioactive materials during an accidental release at the Savannah River Site (SRS). These models are based Gaussian distributions and have been incorporated into an automated menu-driven program called the WIND (Weather INformation and Display) system. The WIND system atmospheric models employ certain assumptions that allow the computations of the ground-level concentration of toxic or radioactive materials to be made quickly. Gaussian models, such as PF/PL and 2DPUF, suffer from serious limitations including the inability to represent recirculation of pollutants in complex terrain, the use of one stability class at a given time to represent turbulent mixing over heterogeneous terrain, and the use of a wind field computed at only one height in the atmosphere. These limitations arise because the fundamental conservation relations of the atmosphere have been grossly simplified. Three-dimensional coupled atmospheric-dispersion models are not limited by the over-simplifications of the Gaussian assumption and have been used in the past to predict the transport of pollutants in a variety of atmospheric circulations. The disadvantage of these models is that they require large amounts of computational time; however, technology has progressed enough so that real-time simulations of dispersion may be made. These complex models can be run in an operational mode so that routine forecasts of the wind field and particulate concentration can be made

  17. HCl in rocket exhaust clouds - Atmospheric dispersion, acid aerosol characteristics, and acid rain deposition

    Science.gov (United States)

    Pellett, G. L.; Sebacher, D. I.; Bendura, R. J.; Wornom, D. E.

    1983-01-01

    Both measurements and model calculations of the temporal dispersion of peak HCl (g + aq) concentration in Titan III exhaust clouds are found to be well characterized by one-term power-law decay expressions. The respective coefficients and decay exponents, however, are found to vary widely with meteorology. The HCl (g), HCl (g + aq), dewpoint, and temperature-pressure-altitude data for Titan III exhaust clouds are consistent with accurately calculated HCl/H2O vapor-liquid compositions for a model quasi-equilibrated flat surface aqueous aerosol. Some cloud evolution characteristics are also defined. Rapid and extensive condensation of aqueous acid clearly occurs during the first three min of cloud rise. Condensation is found to be intensified by the initial entrainment of relatively moist ambient air from lower levels, that is, from levels below eventual cloud stabilization. It is pointed out that if subsequent dilution air at stabilization altitude is significantly drier, a state of maximum condensation soon occurs, followed by an aerosol evaporation phase.

  18. Wage Dispersion in the Search and Matching Model

    OpenAIRE

    Dale T. Mortensen

    2010-01-01

    Matched employer-employee data exhibits both wage and productivity dispersion across firms and suggest that a linear relationship holds between the average wage paid and a firm productivity. The purpose of this paper is to demonstrate that these facts can be explained by a search and matching model when firms are heterogenous with respect to productivity, are composed of many workers, and face diminishing returns to labor given the wage paid to identical workers is the solution to the Stole-Z...

  19. On the thermally stratified atmospheric flow modeling

    Czech Academy of Sciences Publication Activity Database

    Sládek, Ivo; Kozel, K.; Jaňour, Zbyněk

    Praha : Ústav termomechaniky, AV ČR, v. v. i., 2010 - (Příhoda, J.; Kozel, K.), s. 135-138 ISBN 978-80-87012-25-3. [Topical Problems of Fluid Mechanics 2010. Praha (CZ), 10.02.2010-11.02.2010] Institutional research plan: CEZ:AV0Z20760514 Keywords : atmospheric boundary layer * turbulence model * finite volume method Subject RIV: DG - Athmosphere Sciences, Meteorology

  20. Centrifuge modeling of soil atmosphere interaction

    OpenAIRE

    CAICEDO, B; TRISTANCHO, J; THOREL, Luc

    2010-01-01

    Atmosphere process of infiltration or evaporation affect the behavior of geotechnical structures located near the soil surface. This paper focuses on the drying process of soils due to evaporation. The scaling laws are analyzed and afterwards the results on applying two cycles of heating and cooling on a soil mass are presented. Based on these results, conclusions about the feasibility of reproducing evaporation on centrifuge models are recommended.

  1. Atmospheric dispersion simulations of radioactive materials discharged from the Fukushima Daiichi Nuclear Power Plant due to accident. Consideration of deposition process

    International Nuclear Information System (INIS)

    In order to assess the radiological dose to the public resulting from the Fukushima Daiichi Nuclear Power Plant accident in Japan, the spatial and temporal distribution of radioactive materials in the environment have been analyzed by computer simulations. As the first step, the source term of radioactive materials discharged into the atmosphere was estimated by coupling environmental monitoring data with atmospheric dispersion simulations by the System for Prediction of Environmental Emergency Dose Information (SPEEDI) and the Worldwide version of SPEEDI (WSPEEDI-II). By using the estimated source term, detailed analysis on the local dispersion around the plant and regional scale dispersion over the eastern Japan area were carried out by WSPEEDI-II simulations. The formation processes of high dose rate zone around north-west direction from the plant and deposition over the eastern Japan area were reproduced in these simulations. However, there were some discrepancies between calculation and airborne monitoring of surface deposition of 137Cs, and the cause of these discrepancies was investigated. The result of parametric study indicated that the model can reproduce the spatial and temporal distribution of radioactive materials in the environment more accurately by using different wet deposition schemes considering rainout/washout, ice/liquid phases, and fog deposition. (author)

  2. Report of the Nordic dispersion-/trajectory model comparison with the ETEX-1 fullscale experiment

    International Nuclear Information System (INIS)

    On the 6th and 7th June 1995 a meeting was held at Risoe, where calculations of the atmospheric transportation and dispersion of the ETEX-1 release carried out by a number of institutions in the Nordic countries were presented. Also presented were the results of the measurements carried out by the National Environmental Research Institute of Denmark, information previously not known to the participants in the meeting. This provided not only an opportunity of intercomparing the models, but also of carrying out a validation exercise. The main points form the concluding discussions are also included in this report. (au) 7 tabs., 75 ills

  3. How realistic are solar model atmospheres?

    CERN Document Server

    Pereira, Tiago M D; Collet, Remo; Thaler, Irina; Trampedach, Regner; Leenaarts, Jorrit

    2013-01-01

    Recently, new solar model atmospheres have been developed to replace classical 1D LTE hydrostatic models and used to for example derive the solar chemical composition. We aim to test various models against key observational constraints. In particular, a 3D model used to derive the solar abundances, a 3D MHD model (with an imposed 10 mT vertical magnetic field), 1D models from the PHOENIX project, the 1D MARCS model, and the 1D semi-empirical model of Holweger & M\\"uller. We confront the models with observational diagnostics of the temperature profile: continuum centre-to-limb variations (CLV), absolute continuum fluxes, and the wings of hydrogen lines. We also test the 3D models for the intensity distribution of the granulation and spectral line shapes. The predictions from the 3D model are in excellent agreement with the continuum CLV observations, performing even better than the Holweger & M\\"uller model (constructed largely to fulfil such observations). The predictions of the 1D theoretical models ...

  4. Research on simulation technology for CBRN threat assessment system. Prediction technology for atmospheric dispersion of CBRN materials

    International Nuclear Information System (INIS)

    The technical survey is conducted on the CBRN (Chemical, Biological, Radiological and Nuclear) Threat Assessment System Simulation Technology. The dispersion property of CBRN materials is summarized, and the current simulation techniques for CBRN materials dispersion are described. The effects of advection-diffusion, sedimentation by the gravity, buoyancy and wash-out by rainfall on the dispersion property of CBRN materials should be considered in the simulation modeling. The concentration distribution of CBRN materials is predicted through the meteorological analysis, the flow analysis and the dispersion analysis, and the hazard map will be produced from that. A selection of simulation method, model, domain and number of computational grid points is necessary to perform the simulation, considering the balance between calculation cost and prediction accuracy. For construction of CBRN Threat Assessment System, it is important how to integrate the developed simulation element technologies and threat assessment technologies. (author)

  5. Observations and Modeling of Tropical Planetary Atmospheres

    Science.gov (United States)

    Laraia, Anne

    2016-01-01

    This thesis is a comprised of three different projects within the topic of tropical atmospheric dynamics. First, I analyze observations of thermal radiation from Saturn's atmosphere and from them, determine the latitudinal distribution of ammonia vapor near the 1.5-bar pressure level. The most prominent feature of the observations is the high brightness temperature of Saturn's subtropical latitudes on either side of the equator. After comparing the observations to a microwave radiative transfer model, I find that these subtropical bands require very low ammonia relative humidity below the ammonia cloud layer in order to achieve the high brightness temperatures observed. We suggest that these bright subtropical bands represent dry zones created by a meridionally overturning circulation. Second, I use a dry atmospheric general circulation model to study equatorial superrotation in terrestrial atmospheres. A wide range of atmospheres are simulated by varying three parameters: the pole-equator radiative equilibrium temperature contrast, the convective lapse rate, and the planetary rotation rate. A scaling theory is developed that establishes conditions under which superrotation occurs in terrestrial atmospheres. The scaling arguments show that superrotation is favored when the off-equatorial baroclinicity and planetary rotation rates are low. Similarly, superrotation is favored when the convective heating strengthens, which may account for the superrotation seen in extreme global-warming simulations. Third, I use a moist slab-ocean general circulation model to study the impact of a zonally-symmetric continent on the distribution of monsoonal precipitation. I show that adding a hemispheric asymmetry in surface heat capacity is sufficient to cause symmetry breaking in both the spatial and temporal distribution of precipitation. This spatial symmetry breaking can be understood from a large-scale energetic perspective, while the temporal symmetry breaking requires

  6. Atmospheric Dispersion at Spatial Resolutions Below Mesoscale for university of Tennessee SimCenter at Chattanooga: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David Whitfield; Dr. Daniel Hyams

    2009-09-14

    In Year 1 of this project, items 1.1 and 1.2 were addressed, as well as item 2.2. The baseline parallel computational simulation tool has been refined significantly over the timeline of this project for the purpose of atmospheric dispersion and transport problems; some of these refinements are documented in Chapter 3. The addition of a concentration transport capability (item 1.2) was completed, along with validation and usage in a highly complex urban environment. Multigrid capability (item 2.2) was a primary focus of Year 1 as well, regardless of the fact that it was scheduled for Year 2. It was determined by the authors that due to the very large nature of the meshes required for atmospheric simulations at mesoscale, multigrid was a key enabling technology for the rest of the project to be successful. Therefore, it was addressed early according to the schedule laid out in the original proposal. The technology behind the multigrid capability is discussed in detail in Chapter 5. Also in Year 1, the issue of ground topography specification is addressed. For simulations of pollutant transport in a given region, a key prerequisite is the specification of the detailed ground topography. The local topography must be placed into a form suitable for generating an unstructured grid both on the topography itself and the atmospheric volume above it; this effort is documented in Chapter 6. In Year 2 of this project, items 1.3 and 2.1 were addressed. Weather data in the form of wind speeds, relative humidity, and baseline pollution levels may be input into the code in order to improve the real-world fidelity of the solutions. Of course, the computational atmospheric boundary layer (ABL) boundary condition developed in Year 1 may still be used when necessary. Cloud cover may be simulated via the levels of actinic flux allowed in photochemical reactions in the atmospheric chemistry model. The primary focus of Year 2 was the formulation of a multispecies capability with included

  7. NKS NordRisk. Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Havskov Soerensen, J.; Baklanov, A.; Mahura, A. (Danish Meteorological Institute, Copenhagen (Denmark)); Lauritzen, Bent; Mikkelsen, Torben (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2008-07-15

    Within the NKS NordRisk project, 'Nuclear risk from atmospheric dispersion in Northern Europe', the NKS NordRisk Atlas has been developed. The atlas describes risks from hypothetical long-range atmospheric dispersion and deposition of radionuclides from selected nuclear risk sites in the Northern Hemisphere. A number of case studies of long-term long-range atmospheric transport and deposition of radionuclides has been developed, based on two years of meteorological data. Radionuclide concentrations in air and radionuclide depositions have been evaluated and examples of long-term averages of the dispersion and deposition and of the variability around these mean values are provided. (au)

  8. Regional forecasting with global atmospheric models

    International Nuclear Information System (INIS)

    This report was prepared by the Applied Research Corporation (ARC), College Station, Texas, under subcontract to Pacific Northwest Laboratory (PNL) as part of a global climate studies task. The task supports site characterization work required for the selection of a potential high-level nuclear waste repository and is part of the Performance Assessment Scientific Support (PASS) Program at PNL. The work is under the overall direction of the Office of Civilian Radioactive Waste Management (OCRWM), US Department of Energy Headquarters, Washington, DC. The scope of the report is to present the results of the third year's work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain several studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals

  9. Dispersion of sulphur in the northern hemisphere. A study with a 3-dimensional time-resolved model

    Energy Technology Data Exchange (ETDEWEB)

    Tarrason, L.

    1995-12-31

    This thesis on atmospheric dispersion of sulphur presents a calculation of intercontinental transport of oxidized sulphur and allocates different contributions to sulphur background levels over Europe. It is found that a significant fraction of anthropogenic sulphur (AS) is transported out of continental boundaries thus affecting the background levels over major parts of the northern hemisphere. Over Europe, the contribution of AS from North America is similar in amount to that of Asian AS and natural sources from the North Atlantic Ocean. Although the yearly contribution of intercontinental transport to deposition of sulphur over Europe is quite small, it can be much more important over certain areas and seasons and is comparable to the contributions from individual European countries. The calculations are based on a three-dimensional Eulerian time-resolved model that describes sulphur dispersion in the atmosphere in connection with large-scale synoptic flows and agree well with observations. The thesis emphasizes the role of synoptic scale atmospheric motions in determining intercontinental transport of sulphur. It indicates the need to resolve individual cyclones and anticyclones in order to describe the dispersion and distribution of atmospheric sulphur in the northern hemisphere and stresses the value of comparing model calculations with observations, both in atmospheric chemistry studies and in climate applications. 260 refs., 50 figs., 17 tabs.

  10. FEM numerical model study of electrosurgical dispersive electrode design parameters.

    Science.gov (United States)

    Pearce, John A

    2015-08-01

    Electrosurgical dispersive electrodes must safely carry the surgical current in monopolar procedures, such as those used in cutting, coagulation and radio frequency ablation (RFA). Of these, RFA represents the most stringent design constraint since ablation currents are often more than 1 to 2 Arms (continuous) for several minutes depending on the size of the lesion desired and local heat transfer conditions at the applicator electrode. This stands in contrast to standard surgical activations, which are intermittent, and usually less than 1 Arms, but for several seconds at a time. Dispersive electrode temperature rise is also critically determined by the sub-surface skin anatomy, thicknesses of the subcutaneous and supra-muscular fat, etc. Currently, we lack fundamental engineering design criteria that provide an estimating framework for preliminary designs of these electrodes. The lack of a fundamental design framework means that a large number of experiments must be conducted in order to establish a reasonable design. Previously, an attempt to correlate maximum temperatures in experimental work with the average current density-time product failed to yield a good match. This paper develops and applies a new measure of an electrode stress parameter that correlates well with both the previous experimental data and with numerical models of other electrode shapes. The finite element method (FEM) model work was calibrated against experimental RF lesions in porcine skin to establish the fundamental principle underlying dispersive electrode performance. The results can be used in preliminary electrode design calculations, experiment series design and performance evaluation. PMID:26736814

  11. Study on the atmospheric dispersion of pollutant in the presence and absence of a hill for BARC, Trombay site

    International Nuclear Information System (INIS)

    Blocking effects generated by topographical features leads to complex flow patterns that might generate mean concentration distributions significantly different from those that might be expected from the mean flow in the absence of the complex terrain features for atmospheric releases of pollutants. The present paper deals with one such study of the effect of a hill on the atmospheric dispersion of pollutant for BARC, Trombay site. The study of wind flow as well as the atmospheric dispersion of pollutant in the presence of 130 m hill behind PP is found to be important to gauge the radiological consequences on population residing beyond this hill. The results of study of the effect of this hill on the wind flow and the concentration distribution of pollutants on the upwind and downwind side of the hill are presented in the paper. It is seen that the wind flow gets modified leading to deceleration in the upwind side of the hill due to terrain blocking, speed up at the top of the hill and deceleration behind the hill. In the absence of hill, flow remains uniform in the downwind direction. It is also found that in the presence of the hill, the released pollutant disperses more as compared to the absence of the hill. Because of the additional dispersion provided by the hill and also because of the elevated topography, the peak concentration value in the presence of hill is obtained at shorter distance when compared with the other case. The peak ground level concentration value found in the presence of hill is relatively higher; however, for the population residing at farther distances, the additional dilution provided by the hill reduces the ground level concentration. (author)

  12. Atmospheric corrosion: statistical validation of models

    International Nuclear Information System (INIS)

    In this paper we discuss two different methods for validation of regression models, applied to corrosion data. One of them is based on the correlation coefficient and the other one is the statistical test of lack of fit. Both methods are used here to analyse fitting of bi logarithmic model in order to predict corrosion for very low carbon steel substrates in rural and urban-industrial atmospheres in Uruguay. Results for parameters A and n of the bi logarithmic model are reported here. For this purpose, all repeated values were used instead of using average values as usual. Modelling is carried out using experimental data corresponding to steel substrates under the same initial meteorological conditions ( in fact, they are put in the rack at the same time). Results of correlation coefficient are compared with the lack of it tested at two different signification levels (α=0.01 and α=0.05). Unexpected differences between them are explained and finally, it is possible to conclude, at least in the studied atmospheres, that the bi logarithmic model does not fit properly the experimental data. (Author) 18 refs

  13. Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

    Science.gov (United States)

    Sagan, C.

    1974-01-01

    The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

  14. MODELING OF GENERIC AIR POLLUTION DISPERSION ANALYSIS FROM CEMENT FACTORY

    Directory of Open Access Journals (Sweden)

    Moses E EMETERE

    2013-06-01

    Full Text Available Air pollution from cement factory is classified as one of the sources of air pollution. The control of the air pollution by addressing the wind field dynamics was the main objective of the paper. The dynamics of dispersion showed a three way flow which was calculated and explained accordingly. The 3D model showed good level of accuracy by determining field values of air deposited pollutants. Mean concentration of diffusing pollutants was shown to be directly proportional to the plume angular displacement. The 2D model explained the details of the wind field dynamics and proffers a solution which may be relevant in controlling air pollution from anthropogenic sources.

  15. A comparison of operational Lagrangian particle and adaptive puff models for plume dispersion forecasting

    Science.gov (United States)

    Souto, M. J.; Souto, J. A.; Pérez-Muñuzuri, V.; Casares, J. J.; Bermúdez, J. L.

    Transport and dispersion of pollutants in the lower atmosphere are predicted by using both a Lagrangian particle model (LPM) and an adaptive puff model (APM2) coupled to the same mesoscale meteorological prediction model PMETEO. LPM and APM2 apply the same numerical solutions for plume rise; but, for advection and plume growth, LPM uses a stochastic surrogate to the pollutant conservation equation, and APM2 applies interpolated winds and standard deviations from the meteorological model, using a step-wise Gaussian approach. The results of both models in forecasting the SO 2 ground level concentration (glc) around the 1400 MWe coal-fired As Pontes Power Plant are compared under unstable conditions. In addition, meteorological and SO 2 glc numerical results are compared to field measurements provided by 17 fully automated SO 2 glc remote stations, nine meteorological towers and one Remtech PA-3 SODAR, from a meteorological and air quality monitoring network located 30 km around the power plant.

  16. CIDGA - Coupling of Interior Dynamic models with Global Atmosphere models

    Science.gov (United States)

    Noack, Lena; Plesa, Ana-Catalina; Breuer, Doris

    2010-05-01

    Atmosphere temperatures and in particular the surface temperatures mostly depend on the solar heat flux and the atmospheric composition. The latter can be influenced by interior processes of the planet, i.e. volcanism that releases greenhouse gases such as H2O, CO2 and methane into the atmosphere and plate tectonics through which atmospheric CO2 is recycled via carbonates into the mantle. An increasing concentration of greenhouse gases in the atmosphere results in an increase of the surface temperature. Changes in the surface temperature on the other hand may influence the cooling behaviour of the planet and hence influence its volcanic activity [Phillips et al., 2001]. This feedback relation between mantle convection and atmosphere is not very well understood, since until now mostly either the interior dynamic of a planet or its atmosphere was investigated separately. 2D or 3D mantle convection models to the authors' knowledge haven't been coupled to the atmosphere so far. We have used the 3D spherical simulation code GAIA [Hüttig et al., 2008] including partial melt production and coupled it with the atmosphere module CIDGA using a gray greenhouse model for varying H2O concentrations. This way, not only the influence of mantle dynamics on the atmosphere can be investigated, but also the recoupling effect, that the surface temperature has on the mantle dynamics. So far, we consider one-plate planets without crustal and thus volatile recycling. Phillips et al. [2001] already investigated the coupling effect of the surface temperature on mantle dynamics by using simple parameterized convection models for Venus. In their model a positive feedback mechanism has been observed, i.e., an increase of the surface temperature leads to an increase of partial melt and hence an increase of atmosphere density and surface temperature. Applying our model to Venus, we show that an increase of surface temperature leads not only to an increase of partial melt in the mantle; it also

  17. Atmospheric transmittance model for photosynthetically active radiation

    Energy Technology Data Exchange (ETDEWEB)

    Paulescu, Marius; Stefu, Nicoleta; Gravila, Paul; Paulescu, Eugenia; Boata, Remus; Pacurar, Angel; Mares, Oana [Physics Department, West University of Timisoara, V Parvan 4, 300223 Timisoara (Romania); Pop, Nicolina [Department of Physical Foundations of Engineering, Politehnica University of Timisoara, V Parvan 2, 300223 Timisoara (Romania); Calinoiu, Delia [Mechanical Engineering Faculty, Politehnica University of Timisoara, Mihai Viteazu 1, 300222 Timisoara (Romania)

    2013-11-13

    A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms.

  18. Simulation of radioactive plume gamma dose over a complex terrain using Lagrangian particle dispersion model

    International Nuclear Information System (INIS)

    FLEXPART-WRF is a versatile model for the simulation of plume dispersion over a complex terrain in a mesoscale region. This study deals with its application to the dispersion of a hypothetical air borne gaseous radioactivity over a topographically complex nuclear site in southeastern France. A computational method for calculating plume gamma dose to the ground level receptor is introduced in FLEXPART using the point kernel method. Comparison with another similar dose computing code SPEEDI is carried out. In SPEEDI the dose is calculated for specific grid sizes, the lowest available being 250 m, whereas in FLEXPART it is grid independent. Spatial distribution of dose by both the models is analyzed. Due to the ability of FLEXPART to utilize the spatio-temporal variability of meteorological variables as input, particularly the height of the PBL, the simulated dose values were higher than SPEEDI estimates. The FLEXPART-WRF in combination with point kernel dose module gives a more realistic picture of plume gamma dose distribution in a complex terrain, a situation likely under accidental release of radioactivity in a mesoscale range. - Highlights: • Mesoscale atmospheric simulation and comparison with observational data. • Incorporation of point kernel method of plume gamma dose computation. • Dispersion simulation with FLEXPART-WRF and SPEEDI modeling system. • Inter-comparison of simulated gamma dose rates by FLEXPART and SPEEDI

  19. Supermodeling With A Global Atmospheric Model

    Science.gov (United States)

    Wiegerinck, Wim; Burgers, Willem; Selten, Frank

    2013-04-01

    In weather and climate prediction studies it often turns out to be the case that the multi-model ensemble mean prediction has the best prediction skill scores. One possible explanation is that the major part of the model error is random and is averaged out in the ensemble mean. In the standard multi-model ensemble approach, the models are integrated in time independently and the predicted states are combined a posteriori. Recently an alternative ensemble prediction approach has been proposed in which the models exchange information during the simulation and synchronize on a common solution that is closer to the truth than any of the individual model solutions in the standard multi-model ensemble approach or a weighted average of these. This approach is called the super modeling approach (SUMO). The potential of the SUMO approach has been demonstrated in the context of simple, low-order, chaotic dynamical systems. The information exchange takes the form of linear nudging terms in the dynamical equations that nudge the solution of each model to the solution of all other models in the ensemble. With a suitable choice of the connection strengths the models synchronize on a common solution that is indeed closer to the true system than any of the individual model solutions without nudging. This approach is called connected SUMO. An alternative approach is to integrate a weighted averaged model, weighted SUMO. At each time step all models in the ensemble calculate the tendency, these tendencies are weighted averaged and the state is integrated one time step into the future with this weighted averaged tendency. It was shown that in case the connected SUMO synchronizes perfectly, the connected SUMO follows the weighted averaged trajectory and both approaches yield the same solution. In this study we pioneer both approaches in the context of a global, quasi-geostrophic, three-level atmosphere model that is capable of simulating quite realistically the extra

  20. Applying Dispersive Changes to Lagrangian Particles in Groundwater Transport Models

    Science.gov (United States)

    Konikow, L.F.

    2010-01-01

    Method-of-characteristics groundwater transport models require that changes in concentrations computed within an Eulerian framework to account for dispersion be transferred to moving particles used to simulate advective transport. A new algorithm was developed to accomplish this transfer between nodal values and advecting particles more precisely and realistically compared to currently used methods. The new method scales the changes and adjustments of particle concentrations relative to limiting bounds of concentration values determined from the population of adjacent nodal values. The method precludes unrealistic undershoot or overshoot for concentrations of individual particles. In the new method, if dispersion causes cell concentrations to decrease during a time step, those particles in the cell having the highest concentration will decrease the most, and those with the lowest concentration will decrease the least. The converse is true if dispersion is causing concentrations to increase. Furthermore, if the initial concentration on a particle is outside the range of the adjacent nodal values, it will automatically be adjusted in the direction of the acceptable range of values. The new method is inherently mass conservative. ?? US Government 2010.

  1. Modeling flow around bluff bodies and predicting urban dispersion using large eddy simulation.

    Science.gov (United States)

    Tseng, Yu-Heng; Meneveau, Charles; Parlange, Marc B

    2006-04-15

    Modeling air pollutant transport and dispersion in urban environments is especially challenging due to complex ground topography. In this study, we describe a large eddy simulation (LES) tool including a new dynamic subgrid closure and boundary treatment to model urban dispersion problems. The numerical model is developed, validated, and extended to a realistic urban layout. In such applications fairly coarse grids must be used in which each building can be represented using relatively few grid-points only. By carrying out LES of flow around a square cylinder and of flow over surface-mounted cubes, the coarsest resolution required to resolve the bluff body's cross section while still producing meaningful results is established. Specifically, we perform grid refinement studies showing that at least 6-8 grid points across the bluff body are required for reasonable results. The performance of several subgrid models is also compared. Although effects of the subgrid models on the mean flow are found to be small, dynamic Lagrangian models give a physically more realistic subgrid-scale (SGS) viscosity field. When scale-dependence is taken into consideration, these models lead to more realistic resolved fluctuating velocities and spectra. These results set the minimum grid resolution and subgrid model requirements needed to apply LES in simulations of neutral atmospheric boundary layer flow and scalar transport over a realistic urban geometry. The results also illustrate the advantages of LES over traditional modeling approaches, particularly its ability to take into account the complex boundary details and the unsteady nature of atmospheric boundary layer flow. Thus LES can be used to evaluate probabilities of extreme events (such as probabilities of exceeding threshold pollutant concentrations). Some comments about computer resources required for LES are also included. PMID:16683605

  2. Conditions for the formation and atmospheric dispersion of a toxic, heavy gas layer during thermal metamorphism of coal and evaporite deposits by sill intrusion

    Science.gov (United States)

    Storey, Michael; Hankin, Robin K. S.

    2010-05-01

    There is compelling evidence for massive discharge of volatiles, including toxic species, into the atmosphere at the end of the Permian. It has been argued that most of the gases were produced during thermal metamorphism of coal and evaporite deposits in the East Siberia Tunguska basin following sill intrusion (Retallack and Jahren, 2008; Svensen et al., 2009). The release of the volatiles has been proposed as a major cause of environmental and extinction events at the end of the Permian, with venting of carbon gases and halocarbons to the atmosphere leading to global warming and atmospheric ozone depletion (Svensen et al., 2009) Here we consider the conditions required for the formation and dispersion of toxic, heavier than air, gas plumes, made up of a mixture of CO2, CH4, H2S and SO2 and formed during the thermal metamorphism of C- and S- rich sediments. Dispersion models and density considerations within a range of CO2/CH4 ratios and volatile fluxes and temperatures, for gas discharge by both seepage and from vents, allow the possibility that following sill emplacement much of the vast East Siberia Tunguska basin was - at least intermittently - covered by a heavy, toxic gas layer that was unfavorable for life. Dispersion scenarios for a heavy gas layer beyond the Siberian region during end-Permian times will be presented. REFERENCES G. J. Retallack and A. H. Jahren, Methane release from igneous intrusion of coal during Late Permian extinction events, Journal of Geology, volume 116, 1-20, 2008 H. Svensen et al., Siberian gas venting and the end-Permian environmental crisis, Earth and Planetary Science Letters, volume 277, 490-500, 2009

  3. Numerical modeling of atmospheric washout processes

    International Nuclear Information System (INIS)

    For the washout of particles from the atmosphere by clouds and rain one has to distinguish between processes which work in the first phase of cloud development, when condensation nuclei build up in saturated air (Nucleation Aerosol Scavenging, NAS) and those processes which work at the following cloud development. In the second case particles are taken off by cloud droplets or by falling rain drops via collision (Collision Aerosol Scavenging, CAS). The physics of both processes is described. For the CAS process a numerical model is presented. The report contains a documentation of the mathematical equations and the computer programs (FORTRAN). (KW)

  4. Coupling hydrophobic, dispersion, and electrostatic contributions in continuum solvent models

    CERN Document Server

    Dzubiella, J; McCammon, J A

    2005-01-01

    Recent studies of the hydration of micro- and nanoscale solutes have demonstrated a strong {\\it coupling} between hydrophobic, dispersion and electrostatic contributions, a fact not accounted for in current implicit solvent models. We present a theoretical formalism which accounts for coupling by minimizing the Gibbs free energy with respect to a solvent volume exclusion function. The solvent accessible surface is output of our theory. Our method is illustrated with the hydration of alkane-assembled solutes on different length scales, and captures the strong sensitivity to the particular form of the solute-solvent interactions in agreement with recent computer simulations.

  5. Development of a comprehensive testing framework for Lagrangian dispersion models: Application to wet deposition in FLEXPART

    Science.gov (United States)

    Philipp, Anne; Seibert, Petra

    2015-04-01

    Tasks such as inverse modelling and prediction of transport and dispersion of aerosols and soluble gases are increasingly performed by Lagrangian particle models, e.g. FLEXPART (FLEXible PARTicle dispersion model, http://flexpart.eu). Applications include decision making in situations of crisis. Therefore, the credibility in their results should be established through extensive evaluation. Because of this, we are currently developing a testing environment for FLEXPART. This environment is not only going to test the functionality of the model as a whole but also the functionality of its components such as, for example, wet deposition. Test cases and corresponding evaluation already created by FLEXPART developers in the past shall be brought together in this single environment, allowing for efficient testing of future code additions and modifications. Regression testing is being applied, meaning that the collection of test cases for all parts of the model is used to make sure that a change in one part of the model does not negatively affect the behavior of all the other parts, including overall runtime. One component of FLEXPART is the deposition scheme. Because particulate or particle-borne trace substances undergo wet as well as dry deposition, it is an important part of atmospheric transport modelling and it is a major influence factor for the atmospheric lifetime of aerosols and soluble gases. Therefore, we are presenting the development of our testing environment based on the example of the implementation of an improved wet deposition scheme in the latest FLEXPART version. Besides the usual software tests for assessing the functionality, performance and the structure-oriented work flow of the code, we have to show that the physical results of the deposition fields are realistic. The component of the testing environment for a new wet deposition scheme implemented in FLEXPART should compare its results with (i) measured deposition data, (ii) results from previous

  6. User manual of nuclide dispersion in phreatic aquifers model

    International Nuclear Information System (INIS)

    The Nuclide Dispersion in Phreatic Aquifers (DRAF) model was developed in the 'Division Estudios Ambientales' of the 'Gerencia de Seguridad Radiologica y Nuclear, Comision Nacional de Energia Atomica' (1991), for the Safety Assessment of Near Surface Radioactive Waste Disposal Facilities. Afterwards, it was modified in several opportunities, adapting it to a number of application conditions. The 'Manual del usuario del codigo DRAF' here presented is a reference document for the use of the last three versions of the code developed for the 'Autoridad Regulatoria Nuclear' between 1995 and 1996. The DRAF model solves the three dimension's solute transport equation for porous media by the finite differences method. It takes into account the advection, dispersion, radioactive decay, and retention in the solid matrix processes, and has multiple possibilities for the source term. There are three versions of the model, two of them for the saturated zone and one for the unsaturated zone. All the versions have been verified in different conditions, and have been applied in exercises of the International Atomic Energy Agency and also in real cases. (author)

  7. CFD model simulation of LPG dispersion in urban areas

    Science.gov (United States)

    Pontiggia, Marco; Landucci, Gabriele; Busini, Valentina; Derudi, Marco; Alba, Mario; Scaioni, Marco; Bonvicini, Sarah; Cozzani, Valerio; Rota, Renato

    2011-08-01

    There is an increasing concern related to the releases of industrial hazardous materials (either toxic or flammable) due to terrorist attacks or accidental events in congested industrial or urban areas. In particular, a reliable estimation of the hazardous cloud footprint as a function of time is required to assist emergency response decision and planning as a primary element of any Decision Support System. Among the various hazardous materials, the hazard due to the road and rail transportation of liquefied petroleum gas (LPG) is well known since large quantities of LPG are commercialized and the rail or road transportation patterns are often close to downtown areas. Since it is well known that the widely-used dispersion models do not account for the effects of any obstacle like buildings, tanks, railcars, or trees, in this paper a CFD model has been applied to simulate the reported consequences of a recent major accident involving an LPG railcar rupture in a congested urban area (Viareggio town, in Italy), showing both the large influence of the obstacles on LPG dispersion as well as the potentials of CFD models to foresee such an influence.

  8. Model-based guidance and control for atmospheric guided entry

    OpenAIRE

    Canuto, Enrico; Ospina, Jose Alejandro

    2012-01-01

    This paper presents a solution of the translational control for a biconic atmospheric entry capsule using the bank angle as a command. The control algorithm is separated into path planning and reference-path tracking. The path-planning algorithm computes the entry trajectory from the navigated state at the Entry Interface Point until the desired Parachute Deployment Point. The algorithm aims to recover the landing site uncertainty caused by Entry Interface Point dispersions. Atmospheric and a...

  9. The Lagrangian particle dispersion model FLEXPART-WRF version 3.1

    Science.gov (United States)

    Brioude, J.; Arnold, D.; Stohl, A.; Cassiani, M.; Morton, D.; Seibert, P.; Angevine, W.; Evan, S.; Dingwell, A.; Fast, J. D.; Easter, R. C.; Pisso, I.; Burkhart, J.; Wotawa, G.

    2013-11-01

    The Lagrangian particle dispersion model FLEXPART was originally designed for calculating long-range and mesoscale dispersion of air pollutants from point sources, such that occurring after an accident in a nuclear power plant. In the meantime, FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. A need for further multiscale modeling and analysis has encouraged new developments in FLEXPART. In this paper, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run this new model and present special options and features that differ from those of the preceding versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization, and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format, both of which have efficient data compression. In addition, test case data and the source code are provided to the reader as a Supplement. This material and future developments will be accessible at http://www.flexpart.eu.

  10. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2012-03-01

    Full Text Available On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 (133Xe and the aerosol-bound caesium-137 (137Cs, which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2–18.3 EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated 133Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h into 133Xe. There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For 137

  11. Comparison of Average Transport and Dispersion Among a Gaussian Model, a Two-Dimensional Model and a Three-Dimensional Model

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J A; Molenkamp, C R; Bixler, N E; Morrow, C W; Ramsdell, Jr., J V

    2004-05-10

    The Nuclear Regulatory Commission uses MACCS2 (MELCOR Accident Consequence Code System, Version 2) for regulatory purposes such as planning for emergencies and cost-benefit analyses. MACCS2 uses a straight-line Gaussian model for atmospheric transport and dispersion. This model has been criticized as being overly simplistic, although only expected values of metrics of interest are used in the regulatory arena. To test the assumption that averaging numerous weather results adequately compensates for the loss of structure in the meteorology that occurs away from the point of release, average MACCS2 results have been compared with average results from a state-of-the-art, 3-dimensional LODI (Lagrangian Operational Dispersion Integrator)/ADAPT (Atmospheric Data Assimilation and Parameterization Technique) and a Lagrangian trajectory, Gaussian puff transport and dispersion model from RASCAL (Radiological Assessment System for consequence Analysis). The weather sample included 610 weather trials representing conditions for a hypothetical release at the Central Facility of the Department of Energy's Atmospheric Radiation Measurement site. The values compared were average ground concentrations and average surface-level air concentrations at several distances out to 100 miles (160.9 km) from the assumed release site.

  12. Atmospheric dispersion of radon gas from a shallow, extended uranium ore body

    International Nuclear Information System (INIS)

    The effects of meteorological variables on the dispersal of radon and its daughters, under the simplifying condition that the radon is produced from a reasonably uniform, extended plane surface, have been investigated. The Yeelirrie ore body in Western Australia is situated in a semi-desert area, where temperature inversions occur frequently

  13. PCBs in the Arctic atmosphere: determining important driving forces using a global atmospheric transport model

    OpenAIRE

    Friedman, Carey L.; Selin, Noelle E

    2016-01-01

    We present a spatially and temporally resolved global atmospheric polychlorinated biphenyl (PCB) model, driven by meteorological data, that is skilled at simulating mean atmospheric PCB concentrations and seasonal cycles in the Northern Hemisphere midlatitudes and mean Arctic concentrations. However, the model does not capture the observed Arctic summer maximum in atmospheric PCBs. We use the model to estimate global budgets for seven PCB congeners, and we demonstrate that c...

  14. Leakage and atmospheric dispersion of CO2 associated with carbon capture and storage projects

    OpenAIRE

    Mazzoldi, Alberto

    2009-01-01

    Climate change is affecting planet Earth. The main cause is anthropogenic emissions of greenhouse gases, the principal one being carbon dioxide, released in the atmosphere as a by-product of the combustion of hydrocarbons for the generation of energy. Carbon capture and storage (CCS) is a technology that would prevent carbon dioxide from being emitted into the atmosphere by safely sequestering it underground. For so doing, CO2 must be captured at large emission points and transported at high ...

  15. Essays on pricing dynamics, price dispersion, and nested logit modelling

    Science.gov (United States)

    Verlinda, Jeremy Alan

    The body of this dissertation comprises three standalone essays, presented in three respective chapters. Chapter One explores the possibility that local market power contributes to the asymmetric relationship observed between wholesale costs and retail prices in gasoline markets. I exploit an original data set of weekly gas station prices in Southern California from September 2002 to May 2003, and take advantage of highly detailed station and local market-level characteristics to determine the extent to which spatial differentiation influences price-response asymmetry. I find that brand identity, proximity to rival stations, bundling and advertising, operation type, and local market features and demographics each influence a station's predicted asymmetric relationship between prices and wholesale costs. Chapter Two extends the existing literature on the effect of market structure on price dispersion in airline fares by modeling the effect at the disaggregate ticket level. Whereas past studies rely on aggregate measures of price dispersion such as the Gini coefficient or the standard deviation of fares, this paper estimates the entire empirical distribution of airline fares and documents how the shape of the distribution is determined by market structure. Specifically, I find that monopoly markets favor a wider distribution of fares with more mass in the tails while duopoly and competitive markets exhibit a tighter fare distribution. These findings indicate that the dispersion of airline fares may result from the efforts of airlines to practice second-degree price discrimination. Chapter Three adopts a Bayesian approach to the problem of tree structure specification in nested logit modelling, which requires a heavy computational burden in calculating marginal likelihoods. I compare two different techniques for estimating marginal likelihoods: (1) the Laplace approximation, and (2) reversible jump MCMC. I apply the techniques to both a simulated and a travel mode

  16. Comparing the Degree of Land-Atmosphere Interaction in Four Atmospheric General Circulation Models

    Science.gov (United States)

    Koster, Randal D.; Dirmeyer, Paul A.; Hahmann, Andrea N.; Ijpelaar, Ruben; Tyahla, Lori; Cox, Peter; Suarez, Max J.; Houser, Paul R. (Technical Monitor)

    2001-01-01

    Land-atmosphere feedback, by which (for example) precipitation-induced moisture anomalies at the land surface affect the overlying atmosphere and thereby the subsequent generation of precipitation, has been examined and quantified with many atmospheric general circulation models (AGCMs). Generally missing from such studies, however, is an indication of the extent to which the simulated feedback strength is model dependent. Four modeling groups have recently performed a highly controlled numerical experiment that allows an objective inter-model comparison of land-atmosphere feedback strength. The experiment essentially consists of an ensemble of simulations in which each member simulation artificially maintains the same time series of surface prognostic variables. Differences in atmospheric behavior between the ensemble members then indicates the degree to which the state of the land surface controls atmospheric processes in that model. A comparison of the four sets of experimental results shows that feedback strength does indeed vary significantly between the AGCMs.

  17. 2-D model for pollutant dispersion at the coastal outfall off Paradip

    Digital Repository Service at National Institute of Oceanography (India)

    Suryanarayana, A.; Babu, M.T.; Vethamony, P.; Gouveia, A.D

    Simulation of dispersion of the effluent discharge has been carried out using 2-D Model to verify the advection and diffusion of the pollutant patch of the proposed effluent disposal off Paradip, Orissa, India. The simulation of dispersion...

  18. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part I: Source term estimation and local-scale atmospheric dispersion in early phase of the accident

    International Nuclear Information System (INIS)

    The atmospheric release of 131I and 137Cs in the early phase of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident from March 12 to 14, 2011 was estimated by combining environmental data with atmospheric dispersion simulations under the assumption of a unit release rate (1 Bq h−1). For the simulation, WSPEEDI-II computer-based nuclear emergency response system was used. Major releases of 131I (>1015 Bq h−1) were estimated when air dose rates increased in FNPP1 during the afternoon on March 12 after the hydrogen explosion of Unit 1 and late at night on March 14. The high-concentration plumes discharged during these periods flowed to the northwest and south–southwest directions of FNPP1, respectively. These plumes caused a large amount of dry deposition on the ground surface along their routes. Overall, the spatial pattern of 137Cs and the increases in the air dose rates observed at the monitoring posts around FNPP1 were reproduced by WSPEEDI-II using estimated release rates. The simulation indicated that air dose rates significantly increased in the south–southwest region of FNPP1 by dry deposition of the high-concentration plume discharged from the night of March 14 to the morning of March 15. - Highlights: ► Source term during the Fukushima Dai-ichi Nuclear Power Plant accident was estimated. ► Atmospheric dispersion simulation was carried out for estimation. ► Major releases were estimated in the afternoon on March 12 and the night on March 14. ► Air dose rate increased due to dry deposition during the night of March 14.

  19. Long period study of outdoor radon concentration in Milan and correlation between its temporal variations and dispersion properties of atmosphere

    International Nuclear Information System (INIS)

    The results of a survey of outdoor radon concentrations in Milan are reported. Measurements were performed hourly over a continuous four year period from January 1997 to December 2000. Radon concentration was obtaine by two means: both direct measurement of radon; and measurement of its decay products. The average daily pattern of radon concentration featured a minimum in the late afternoon and a maximum in the early hours of the morning.A seasonal pattern with higher concentrations in winter than in summer (fro around 15 Bq m-3 in winter to around 5 Bq m-3 in summer) was also observed. Similar average annual values of around 10 Bq m-3 were obtained. The annual effective outdoor radon dose was found to be 0.12 mSv. The variation from minimum in the afternoon to maximum the following morning was found to be a good indicator of the height of the nocturnal mixing layer. The variation between maximum and minimum levels on the same day is an index of the maximum height of the mixing layer. Furthermore, our long term measurements of radon have permitted us to examine the dispersion characteristics of the atmosphere over Milan, and to establish the frequency of conditions unfavourable to the dispersion of atmospheric pollutants

  20. The Lagrangian particle dispersion model FLEXPART-WRF version 3.0

    Science.gov (United States)

    Brioude, J.; Arnold, D.; Stohl, A.; Cassiani, M.; Morton, D.; Seibert, P.; Angevine, W.; Evan, S.; Dingwell, A.; Fast, J. D.; Easter, R. C.; Pisso, I.; Burkhart, J.; Wotawa, G.

    2013-07-01

    The Lagrangian particle dispersion model FLEXPART was originally designed for calculating long-range and mesoscale dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant. In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. This multiscale need has encouraged new developments in FLEXPART. In this document, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run and present special options and features that differ from its predecessor versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format with efficient data compression. In addition, test case data and the source code are provided to the reader as Supplement. This material and future developments will be accessible at http://www.flexpart.eu.

  1. The Lagrangian particle dispersion model FLEXPART-WRF version 3.0

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2013-07-01

    Full Text Available The Lagrangian particle dispersion model FLEXPART was originally designed for calculating long-range and mesoscale dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant. In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. This multiscale need has encouraged new developments in FLEXPART. In this document, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF mesoscale meteorological model. We explain how to run and present special options and features that differ from its predecessor versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF format with efficient data compression. In addition, test case data and the source code are provided to the reader as Supplement. This material and future developments will be accessible at http://www.flexpart.eu.

  2. Simulating Flow and Dispersion by Using WRF-CFD Coupled Model in a Built-Up Area of Shenyang, China

    Directory of Open Access Journals (Sweden)

    Yijia Zheng

    2015-01-01

    Full Text Available Results are presented from a series of numerical studies designed to investigate the atmospheric boundary layer structure, ambient wind, and pollutant source location and their impacts on the wind field and pollutant distribution within the built-up areas of Shenyang, China. Two models, namely, Open Source Field Operation and Manipulation (OpenFOAM software package and Weather Research and Forecasting (WRF model, are used in the present study. Then the high resolution computational fluid dynamics (CFD numerical experiments were performed under the typical simulated atmospheric boundary conditions. It was found that the atmospheric boundary structure played a crucial role in the pollution within the building cluster, which determined the potential turbulent diffusion ability of the atmospheric surface layer; the change of the ambient wind direction can significantly affect the dispersion pattern of pollutants, which was a more sensitive factor than the ambient wind speed; under a given atmospheric state, the location of the pollution sources would dramatically determine the pollution patterns within built-up areas. The WRF-CFD numerical evaluation is a reliable method to understand the complicated flow and dispersion within built-up areas.

  3. Modeling of dilute and dense dispersed fluid-particle flow

    Energy Technology Data Exchange (ETDEWEB)

    Laux, Harald

    1998-08-01

    A general two-fluid model is derived and applied in CFD computations to various test cases of important industrial multiphase flows. It is general in the sense of its applicability to dilute and dense dispersed fluid-particle flows. The model is limited to isothermal flow without mass transfer and only one particle phase is described. The instantaneous fluid phase equations, including the phase interaction terms, are derived from a volume averaging technique, and the instantaneous particle phase equations are derived from the kinetic theory of granular material. Whereas the averaging procedure, the treatment of the interaction terms, and the kinetic theory approach have been reported in literature prior to this work the combination of the approaches is new. The resulting equations are derived without ambiguity in the interpretation of the particle phase pressure (equation-of-state of particle phase). The basic modeling for the particle phase is improved in two steps. Because in the basic modeling only stresses due to kinetic and collisional interactions are included, a simple model for an effective viscosity is developed in order to allow also frictional stresses within the particle phase. Moreover, turbulent stresses and turbulent dispersion of particles play often an important role for the transport processes. Therefore in a second step, a two-equation turbulence model for both fluid and particle phase turbulence is derived by applying the phasic average to the instantaneous equations. The resulting k-{epsilon}-k{sup d}-{epsilon}{sup d} model is new. Mathematical closure is attempted such that the resulting set of equations is valid for both dilute arid dense flows. During the development of the closure relations a clear distinction is made between granular or ''viscous'' microscale fluctuations and turbulent macro scale fluctuations (true particle turbulence) within the particle phase. The set of governing equations is discretized by using a

  4. Dispersion model for airborne particulates inside a building

    International Nuclear Information System (INIS)

    An empirical model has been developed for the spread of airborne radioactive particles after they are released inside a building. The model has been useful in performing safety analyses of actinide materials facilities at the Savannah River Plant (SRP). These facilities employ the multiple-air-zone concept; that is, ventilation air flows from rooms or areas of least radioactive material hazard, through zones of increasing hazard, to a treatment system. A composite of the data for dispersion of airborne activity during 12 actual case incidents at SRP forms the basis for this model. These incidents occurred during approximately 90 plant-years of experience at SRP with the chemical and metallurgical processing of purified neptunium and plutonium after their recovery from irradiated uranium. The model gives ratios of the airborne activity concentrations in rooms and corridors near the site of the release. The multiple-air-zone concept has been applied to many designs of nuclear facilities as a safety feature to limit the spread of airborne activity from a release. The model illustrates the limitations of this concept: it predicts an apparently anomalous behavior of airborne particulates; namely, a small migration against the flow of the ventilation air

  5. Evaluating atmospheric methane inversion model results for Pallas, northern Finland

    OpenAIRE

    Tsuruta, Aki; Aalto, Tuula; Backman, Leif; Peters, Wouter; Krol, Maarten; van der Laan-Luijkx, Ingrid T.; Hatakka, Juha; Heikkinen, Pauli; Dlugokencky, Edward J.; Spahni, Renato; Paramonova, Nina N.

    2015-01-01

    A state-of-the-art inverse model, CarbonTracker Data Assimilation Shell (CTDAS), was used to optimize estimates of methane (CH4) surface fluxes using atmospheric observations of CH4 as a constraint. The model consists of the latest version of the TM5 atmospheric chemistry-transport model and an ensemble Kalman filter based data assimilation system. The model was constrained by atmospheric methane surface concentrations, obtained from the World Data Centre for Greenhouse Gases (WDCGG). Pri...

  6. Critical review of hydraulic modeling on atmospheric heat dissipation

    International Nuclear Information System (INIS)

    Objectives of this study were: to define the useful roles of hydraulic modeling in understanding the predicting atmospheric effects of heat dissipation systems; to assess the state-of-the-art of hydraulic modeling of atmospheric phenomena; to inventory potentially useful existing hydraulic modeling facilities both in the United States and abroad; and to scope hydraulic model studies to assist the assessment of atmospheric effects of nuclear energy centers

  7. Impact of Open-cut Coal Mine Terrain Complexity on Atmospheric Dispersion

    Czech Academy of Sciences Publication Activity Database

    Nosek, Štěpán; Jaňour, Zbyněk; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Gulíková, E.

    Guildford : University of Surrey, 2013. ISBN N. [PHYSMOD 2013. Guildford (GB), 16.09.2013-18.09.2013] R&D Projects: GA TA ČR TA01020428 Institutional support: RVO:61388998 Keywords : wind tunnel * atmospheric boundary layer * air pollution * complex terrain * small scale

  8. Improving the low temperature dyeability of polyethylene terephthalate fabric with dispersive dyes by atmospheric pressure plasma discharge

    Science.gov (United States)

    Elabid, Amel E. A.; Zhang, Jie; Shi, Jianjun; Guo, Ying; Ding, Ke; Zhang, Jing

    2016-07-01

    Polyethylene terephthalate (PET) fiber and textile is one of the largest synthetic polymer commodity in the world. The great energy consumption and pollution caused by the high temperature and pressure dyeing of PET fibers and fabrics with disperse dyes has been caused concern these years. In this study, an atmospheric pressure plasma with fine and uniform filament discharge operated at 20 kHz has been used to improve the low temperature dyeability of PET fabric at 95 °C with three cation disperse dyes: Red 73, Blue 183 and Yellow 211. The dyes uptake percentage of the treated PET fabrics was observed to increase as twice as much of untreated fabric. The color strength rate was increased more than 20%. The reducing of the water contact angle and the raising of the capillary height of treated PET fabric strip indicate its hydrophilicity improvement. Scanning electron microscope (SEM) results display nano to micro size of etching pits appeared uniformly on the fiber surface of the treated PET. Simultaneously, X-ray photoelectron spectroscopy (XPS) analysis indicates an increase of the oxygen content in the surface caused by the introduction of polar groups such as Cdbnd O and COOH. The rough surface with improved polar oxygen groups showed hydrophilicity and affinity to C.I. dispersive dyes and is believed to be caused by the strong and very fine filament discharge appearing randomly at one place at an instant but evenly at many places at a longer period. This increases the diffusion and absorption of the C.I. disperse dyes on the PET fiber surface, which improve its low temperature dyeability.

  9. Instantaneous and time-averaged dispersion and measurement models for estimation theory applications with elevated point source plumes

    Science.gov (United States)

    Diamante, J. M.; Englar, T. S., Jr.; Jazwinski, A. H.

    1977-01-01

    Estimation theory, which originated in guidance and control research, is applied to the analysis of air quality measurements and atmospheric dispersion models to provide reliable area-wide air quality estimates. A method for low dimensional modeling (in terms of the estimation state vector) of the instantaneous and time-average pollutant distributions is discussed. In particular, the fluctuating plume model of Gifford (1959) is extended to provide an expression for the instantaneous concentration due to an elevated point source. Individual models are also developed for all parameters in the instantaneous and the time-average plume equations, including the stochastic properties of the instantaneous fluctuating plume.

  10. An Axial Dispersion Model for Evaporating Bubble Column Reactor

    Institute of Scientific and Technical Information of China (English)

    谢刚; 李希

    2004-01-01

    Evaporating bubble column reactor (EBCR) is a kind of aerated reactor in which the reaction heat is removed by the evaporation of volatile reaction mixture. In this paper, a mathematical model that accounts for the gas-liquid exothermic reaction and axial dispersions of both gas and liquid phase is employed to study the performance of EBCR for the process of p-xylene(PX) oxidation. The computational results show that there are remarkable concentration and temperature gradients in EBCR for high ratio of height to diameter (H/DT). The temperature is lower at the bottom of column and higher at the top, due to rapid evaporation induced by the feed gas near the bottom. The concentration profiles in the gas phase are more nonuniform than those (except PX) in the liquid phase, which causes more solvent burning consumption at high H/DT ratio. For p-xylene oxidation, theo ptimal H/DT is around 5.

  11. A CFD model for pollutant dispersion in rivers

    Directory of Open Access Journals (Sweden)

    Modenesi K.

    2004-01-01

    Full Text Available Studies have shown that humankind will experience a water shortage in the coming decades. It is therefore paramount to develop new techniques and models with a view to minimizing the impact of pollution. It is important to predict the environmental impact of new emissions in rivers, especially during periods of drought. Computational fluid dynamics (CFD has proved to be an invaluable tool to develop models able to analyze in detail particle dispersion in rivers. However, since these models generate grids with thousands (even millions of points to evaluate velocities and concentrations, they still require powerful machines. In this context, this work contributes by presenting a new three-dimensional model based on CFD techniques specifically developed to be fast, providing a significant improvement in performance. It is able to generate predictions in a couple of hours for a one-thousand-meter long section of river using Pentium IV computers. Commercial CFD packages would require weeks to solve the same problem. Another innovation inb this work is that a half channel with a constant elliptical cross section represents the river, so the Navier Stokes equations were derived for the elliptical system. Experimental data were obtained from REPLAN (PETROBRAS refining unit on the Atibaia River in São Paulo, Brazil. The results show good agreement with experimental data.

  12. Lithospheric Thickness Modeled from Long Period Surface Wave Dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Pasyanos, M E

    2008-05-15

    The behavior of surface waves at long periods is indicative of subcrustal velocity structure. Using recently published dispersion models, we invert surface wave group velocities for lithospheric structure, including lithospheric thickness, over much of the Eastern Hemisphere, encompassing Eurasia, Africa, and the Indian Ocean. Thicker lithosphere under Precambrian shields and platforms are clearly observed, not only under the large cratons (West Africa, Congo, Baltic, Russia, Siberia, India), but also under smaller blocks like the Tarim Basin and Yangtze craton. In contrast, it is found that remobilized Precambrian structures like the Saharan Shield and Sino-Korean Paraplatform do not have well-established lithospheric keels. The thinnest lithospheric thickness is found under oceanic and continental rifts, as well as along convergence zones. We compare our results to thermal models of continental lithosphere, lithospheric cooling models of oceanic lithosphere, lithosphere-asthenosphere boundary (LAB) estimates from S-wave receiver functions, and velocity variations of global tomography models. In addition to comparing results for the broad region, we examine in detail the regions of Central Africa, Siberia, and Tibet. While there are clear differences in the various estimates, overall the results are generally consistent. Inconsistencies between the estimates may be due to a variety of reasons including lateral and depth resolution differences and the comparison of what may be different lithospheric features.

  13. Study on fitness functions of genetic algorithm for dynamically correcting nuclide atmospheric diffusion model

    International Nuclear Information System (INIS)

    Background: In radioactive nuclides atmospheric diffusion models, the empirical dispersion coefficients were deduced under certain experiment conditions, whose difference with nuclear accident conditions is a source of deviation. A better estimation of the radioactive nuclide's actual dispersion process could be done by correcting dispersion coefficients with observation data, and Genetic Algorithm (GA) is an appropriate method for this correction procedure. Purpose: This study is to analyze the fitness functions' influence on the correction procedure and the forecast ability of diffusion model. Methods: GA, coupled with Lagrange dispersion model, was used in a numerical simulation to compare 4 fitness functions' impact on th