Journal of Mechanical Engineering 52 (2006) 6

 

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Modelling of the Stratified Atmosphere in a Nuclear Power Plant Experimental Facility with a Lumped-Parameter Description

Corresponding author - Ivo Kljenak

Authors - Borut Mavko - Aljaž Škerlavaj

Abstract

In this paper we describe the modelling of a non-homogeneous multi-component atmosphere in a multi-compartment nuclear power plant containment using a lumped-parameter approach. The modelling is applied to the topic of hydrogen behaviour in the containment at accident conditions. The main benefit of the proposed approach is the possibility of modelling the phenomena in complex, multi-compartment containments. As an illustration, the experiment E11.2 “Hydrogen distribution in loop flow geometry”, which was performed in the integral experimental facility “Heissdampf Reaktor” (HDR) in Germany, was simulated. A lumped-parameter input model of the HDR facility was developed for the computer code CONTAIN. The calculated pressure, temperature and hydrogen concentrations are compared to experimental values. A good qualitative prediction of the atmosphere stratification was achieved, which supports the adequacy of the lumped-parameter approach.

Keywords - lumped-parameter models, mixing, stratified atmosphere, CONTAIN

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)6, 340-358
UDC 621.039.536:004.94

Modelling of the Stratified Atmosphere in a Nuclear Power Plant Experimental Facility with a Lumped-Parameter Description (pdf)

 

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An Analysis of the Influence of Pedestrians’ Traffic Flow on the Capacity of a Roundabout Using the Discrete Simulation Method

Corresponding author - Tomaž Tollazzi

Authors - Tone Lerher - Matjaž Šraml

Abstract

Like with other non-traffic-lighted intersections, the capacity of roundabouts can be reduced by special traffic conditions. In such cases the pedestrian’s and/or cyclist’s traffic flow, crossing one or more roundabout arms, is the size that influences the roundabout filling or emptying. The purpose of this paper is to show how the use of discrete simulation methods contributes to the decision on implementing a roundabout, or to help decide if the roundabout is going to fulfil appropriately the condition of the expected flow of pedestrians and/or cyclists. A new approach is suggested for dimensioning roundabouts, with mathematical modelling of the traffic flows using the discrete simulation method, and considering the statistically evaluated entry data for vehicles’ and pedestrians’ traffic flows. The simulation results are useful when determining the capacity of foreseen and suggested roundabouts, which will function in different circumstances.  The presented model derives from the expected time void in the vehicles’ traffic flow, used by the pedestrians, assuming their right of way when joining the traffic. The simulation analysis was verified on a real example of a montage roundabout in Koroška Street in Maribor, where measurements of the motorised vehicles’ traffic flow, and pedestrians’ and cyclists’ traffic flow were made. The procedure, shown in the paper, along with the scientific approach to mathematical modelling, presents a practical method, helpful when deciding whether to implement a roundabout in the case of heavy pedestrians’ and/or cyclists’ traffic flows.

Keywords - roundabouts, traffic flow, influence analysis, simulation models

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)6, 359-379
UDC 625.739:004.94

An Analysis of the Influence of Pedestrians’ Traffic Flow on the Capacity of a Roundabout Using the Discrete Simulation Method (pdf)

 

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Model of an Accident-Induced Fire around a Nuclear Power Plant

Corresponding author - Peter Vidmar

Authors - Stojan Petelin

Abstract

The basic aim of this paper is to research the relevant features of the control and management of an outdoor fire event and its influence on the safety of the surrounding area. The work is based on an analytical study of the fire’s origin, its development and spread. A computer program called FDS (Fire Dynamic Simulator) is used in the work to simulate the fire’s behaviour. A program based on the CFD (Computational Fluid Dynamic) model using the LES (Large Eddie Simulation) is used to calculate the fire’s development and the spread of the combustion products in the environment. The fire’s source is located in the vicinity of a hazardous plant, e.g., a power or chemical plant. The article presents the brief background of the FDS computer program and the initial and boundary conditions used in the mathematical model. The output data is discussed and the validity of the results is checked. The work also presents some corrections to the physical model used and its validation by experimental data, which influences the quality of results. The obtained results were discussed and compared with the Fire Safety Analysis report included in the Probabilistic Safety Assessment of the Krško nuclear power plant.

Keywords - fire safety, safety analysis, models, smoke concentrations, hazardous range

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)6, 380-391
UDC 614.84:004.94

Model of an Accident-Induced Fire around a Nuclear Power Plant (pdf)

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The Application of an Atypical Neural Network when Quantifying the Modeling of Environmental Aspects

Corresponding author - Jelena Jovanović

Authors - Zdravko Krivokapić

Abstract

This paper looks at the environmental aspects’ quantification phase, where a new method based on a neural network was initiated. The method should provide sufficient objectivity and accuracy in the assessment of environmental impacts for all types of organization, and it is based on the specificity of available mathematical models used by certified organizations in Serbia & Montenegro.

Keywords - neural networks, environmental protection, environmental aspect, environmental impact, quantification

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)6, 392-403
UDC 519.65:504.06

The Application of an Atypical Neural Network when Quantifying the Modeling of Environmental Aspects (pdf)

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The Estimated Influence of the Input Parameters in the analysis of the PTS in the Core of the PWR Krško NPP in the Case of the SB LOCA

Corresponding author - Ivica Bašić

Authors - Peter Crnjac

Abstract

This paper focuses on the deterministic method of limiting cases of the Krško Nuclear Power Plant (NPP) reactor pressure-vessel cooling by mediating the emergency core-cooling system (ECCS) during a small-break loss-of-coolant accident (SB LOCA). The SB LOCA accident with the equivalent diameter break of 50.8 mm in the cold leg and the RELAP5/MOD3.3 computer code were selected for the basic calculation. In further study, by modifying the ECCS’s parameters for the same break, three accidents of the SB LOCA were simulated. The purpose of our study was to estimate the potential risk of the extreme conservative input parameters for the pressurized thermal shock  (PTS) in the reactor’s pressure vessel.

Keywords - nuclear reactors, pressure vessels, pressurized thermal chock, SB LOCA accident

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)6, 404-418
UDC 621.039.577:621.039.58

The Estimated Influence of the Input Parameters in the analysis of the PTS in the Core of the PWR Krško NPP in the Case of the SB LOCA (pdf)

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An Accuracy Assessment of Satellite Navigation in Natural-Resource Management

Corresponding author - Tomislav Hengl
Authors - Mladen Jurišić - Ivan Martinić

Abstract

This article deals with the possibilities of applying GPS navigation technology to the management of natural resources. It is based on the results of GPS soil mapping at about 30 locations in Baranja (eastern Croatia). The GPS receivers were used primarily for the positioning of the soil-sampling sites. Dynamic mapping was not monitored. The practical purpose of the research was to learn more about working with GPS data, integrating GPS into geographic information system (GIS), and testing the possibilities of the more precise Differential GPS (DGPS). The differences between the data obtained using three methods of point positioning in space were tested: a) geo-referenced aerial photographs (AERO), b) a standard GPS signal, and c) a corrected DGPS signal. A systematic deviation and an error radius were established with respect to the reference value (the DGPS results). Testing the difference between the GPS and AERO did not show any statistically significant difference between these two methods. According to the results of the research, GPS positioning can be successfully applied to soil mapping and to natural-resource inventories in general. Positioning with an uncorrected GPS signal provides equal or better positioning accuracy than that obtained from aerial photographs at an approximate scale of 1:20,000. The use of satellite positioning depends on the needs of a given user group, where aspects relating to precision, a 95% probability radius, the reliability of results and the feasibility are of particular importance.

Keywords - satellite navigation, GPS, precision agriculture, forest management, accuracy assessment

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)6, 419-431
UDC 629.7.05:528.9

An Accuracy Assessment of Satellite Navigation in Natural-Resource Management (pdf)

  

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