44 research outputs found

    GIS as a Decision Support Tool in the Area of Influence of the Nuclear Complex Angra dos Reis, Brazil

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    The outlook concerning the occurrence of industrial accidents has led to the implementation of response systems based on geoprocessing tools, which are widely adopted in emergency for such ventures, since they have helped and served as a support for decision making, as well as for the preparation of guidelines aimed at managing emergencies. Nuclear power plants, because they constitute types of industrial activities that present dangerous conditions and attention regarding security are characterized as hazardous, especially due to consequences that occurred from large accidents— such as Chernobyl (1986) and Fukushima (2011)—highlighting the importance to its negative impacts, since the occurrence of accidents at nuclear power plants may affect surrounding areas, thus exposing a set of elements that are part of the environmental dynamics that integrates the catchment area where this type of plant is situated. In this way, through an integrated view of the region where the nuclear complex is located in Angra dos Reis City (Rio de Janeiro State) and, also, by aggregating information that portray the geobiophysical reality of its surroundings, several elements were incorporated into a database developed in a virtual environment, in which was produced a geographic information system (GIS) that presents a complex of variables that, once considered, can enhance various analysis in order to support emergency situations and planning, as well as guidelines that help define actions from the occurrence of accidental events at the nuclear plant.Indisponível

    Air quality photochemical study over Amazonia Area, Brazil

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    This work presents the results of a photochemical modelling system composed of MM5-SMOKE-CMAQ on Brazilian Amazonia area, been a pioneered implementation task. These results focus on the biogenic and biomass burning emissions and the impact of these emissions on regional air quality. Global and local anthropogenic emissions data, satellite-derived biomass burning inventories, and biogenic emissions calculated with MEGAN model were used to estimate emissions over the domain. The goal is the development of air quality model input data for CMAQ. Results are consistent with O3 formation theory and CO hotspot concentration matches with the geographic area of biomass burning.IndisponĂ­vel

    Analytical solution for the advection–dispersion transport equation in layered media

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    The advection–dispersion transport equation with first-order decay was solved analytically for multi-layered media using the classic integral transform technique (CITT). The solution procedure used an associated non-self-adjoint advection–diffusion eigenvalue problem that had the same form and coefficients as the original problem. The generalized solution of the eigenvalue problem for any numbers of layers was developed using mathematical induction, establishing recurrence formulas and a transcendental equation for determining the eigenvalues. The orthogonality property of the eigenfunctions was found using an integrating factor that transformed the non-self-adjoint advection–diffusion eigenvalue problem into a purely diffusive, self-adjoint problem. The performance of the closed-form analytical solution was evaluated by solving the advection–dispersion transport equation for two- and five-layer media test cases which have been previously reported in the literature. Additionally, a solution featuring first-order decay was developed. The analytical solution reproduced results from the literature, and it was found that the rate of convergence for the current solution was superior to that of previously published solutions.Indisponível

    Integral transform solutions for atmospheric pollutant dispersion

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    A transient two-dimensional advection–diffusion model describing the turbulent dispersion of pollutants in the atmosphere has been solved via the Generalized Integral Transform Technique (GITT), by two different schemes. The first approach performs numerical integration of the transformed system using available routines for initial value problems with automatic error control. In spite of the time-consuming character of such a scheme, its flexibility allows the handling of problems involving time-dependent meteorological parameters such as wind speed and eddy diffusivities. The second approach works fully analytically being thus intrinsically more robust and economic, although not directly applicable in dealing with time-dependent parameters. For the test problem used in this work, both methods agree very well with each other, as well as with a known analytical solution for a simpler formulation used as benchmark. The impact of the longitudinal diffusivity on the stiffness of the ordinary differential equation (ODE) system arising from the integral transformation has been assessed through the processing time demanded to solve it when the numerical approach is used. The observed CPU times show that the analytical approach is clearly preferable unless the problem involves time-dependent parameters.Indisponível

    Analytical solution of the advection–diffusion transport equation using a change-of-variable and integral transform technique

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    This paper presents a formal exact solution of the linear advection–diffusion transport equation with constant coefficients for both transient and steady-state regimes. A classical mathematical substitution transforms the original advection–diffusion equation into an exclusively diffusive equation. The new diffusive problem is solved analytically using the classic version of Generalized Integral Transform Technique (GITT), resulting in an explicit formal solution. The new solution is shown to converge faster than a hybrid analytical–numerical solution previously obtained by applying the GITT directly to the advection–diffusion transport equation.Indisponível

    Computational Decision Support Systems Applied to Decision-Making Process in the Emergency Planning of the Angra dos Reis Nuclear Power Complex – Brazil

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    Industrial accidents pose risks to the entire environment located in the area of influence of the enterprises, especially when they are affected by the atmospheric dispersion of pollutants emitted, as in the case of a nuclear power plant, where the concern with the evacuation of the population is the main priority in critical situations , which reinforces the implementation of actions to support emergency planning and its management, whose support tools, among them the computational modeling that, based on atmospheric models and geographic information systems, are essential in the decision making process. Thus, based on the Angra dos Reis nuclear complex and the impacts that may affect its surroundings, studies using the integrated use of computational platforms served to evaluate the risks and consequences of a hypothetical accidental event, including the calculation of the thermo- source of nuclear fuel, meteorological characteristics, mechanisms of atmospheric dispersion of pollutants, as well as socio-environmental aspects of the region. Meteorological data (wind regime) characterize the wind field from the WRF model, which subsidized the dispersion of radionuclides calculated in the HYSPLIT, information associated with socioenvironmental data (landslides, population density, etc.), incorporated in a GIS database. The results demonstrate the importance of the integrated use of computational systems as tools that support decision-making, potentializing the application of solutions that contribute to support actions and guidelines of planning and governance in emergency situations

    A unified analytical solution of the steady-state atmospheric diffusion equation

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    A unified analytical solution of the steady-state atmospheric diffusion equation for a finite and semi-infinite/infinite media was developed using the classic integral transform technique (CITT) which is based on a systematized method of separation of variable. The solution was obtained considering an arbitrary mean wind velocity depending on the vertical coordinate (z) and a generalized separable functional form for the eddy diffusivities in terms of the longitudinal (x) and vertical coordinates (z). The examples described in this article show that the well known closed-form analytical solutions, available in the literature, for both finite and semi-infinite/infinite media are special cases of the present unified analytical solution. As an example of the strength of the developed methodology, the Copenhagen and Prairie Grass experiments were simulated (finite media with the mean wind speed and the turbulent diffusion coefficient described by different functional forms). The results indicate that the present solutions are in good agreement with those obtained using other analytical procedures, previously published in the literature. It is important to note that the eigenvalue problem is associated directly to the atmospheric diffusion equation making possible the development of the unified analytical solution and also resulting in the improvement of the convergence behavior in the series of the eigenfunction-expansion.IndisponĂ­vel

    Vulnerability Factors for Emergency Planning of the Angra dos Reis Nuclear Power Complex - RJ

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    The Angra dos Reis nuclear power complex, on the southern coast of the state of Rio de Janeiro, has in its geographic space different aspects that integrate the environmental dynamics of its area of influence, where geological, meteorological and demographic factors characterize the region as an environment complex, especially with the projection of emergency actions from an accidental event, especially from the point of view of the evacuation of the population in the impacted areas, presenting particularities that contribute to act as a negative impact in emergency situations, mainly in the phase response to a possible accident. With the support of geographic information systems (GIS), analyzes were made between the susceptibility to landslides and their occurrences (inventory of years 2007-2011), associating the rainfall regime and population density, aspects that demonstrate the vulnerability of the region, especially along the BR-101 highway, with the potential to render escape routes unfeasible in critical situations. The integrated analysis of these factors pointed out that, together, such elements are important bottlenecks for emergency situations in the region, and should be included as critical factors to be analyzed in order to contribute to subsidize actions and guidelines that should be applied in local emergency plannin
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