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Pressurized Water Nuclear Reactor Downcomer Flow Simulation : diplomsko delo
Aljaž Kekec, 2021, diplomsko delo

Opis: In the diploma thesis the flow pattern and conditions in the downcomer of a pressurized water nuclear reactor were simulated, to study coolant mixing inside the primary circuit. This was done using computational dynamics software Ansys CFX. The nuclear reactor in Krško (Slovenia) was used as a basis for the model. The downcomer geometry was simplied for a more feasible study. Three separate simulations were done: one with normal conditions, one with loss of coolant accident conditions and one with a modified geometry. The flow was then studied at different condition at the same levels using velocity contours. The results showed that the axial velocity profiles at the downcomer outlet are not completely uniform.
Ključne besede: Nuclear Power Plant, Pressurized Water Reactor, Downcomer, Flow simulation, Ansys CFX
Objavljeno v DKUM: 13.10.2021; Ogledov: 236; Prenosov: 22
.pdf Celotno besedilo (2,49 MB)

Simulation of flow conditions in nuclear power plant reactor pressure vessel lower plenum experimental facility : master's thesis
Blaž Kamenik, 2019, magistrsko delo

Opis: The flow conditions during the experiment LIVE2D on reactor core melt behaviour in the lower plenum of a reactor pressure vessel, performed at the Karlsruhe Institute of Technology (Germany), were simulated with a Computational Fluid Dynamics computer code. In this hypothetical severe accident scenario in a pressurized water reactor nuclear power plant, the melt is divided into an oxidic layer and a metallic layer on top of it, and the oxidic layer is volumetrically heated due to decay heat. In the experiment, oil and salt were used as simulant materials for metallic and oxidic melt, respectively. The main goal of performed simulations was to investigate the so-called “focusing effect”, where a thin layer of the reactor vessel steel wall is exposed to high heat flux. Due to the length of experiment, which exceeds 100 hours, only intervals of the melt behaviour were simulated. Four cases were simulated. The first case investigated different boundary conditions for the oil layer behaviour for layer thickness 35 mm. The second case investigated the same conditions with added modelling of the reactor vessel steel wall and salt crust from the lower layer. The third case used similar modelling as the second case to investigate the oil layer behaviour for layer thickness 75 mm. The fourth case investigated both salt and oil layers for oil layer thickness 75 mm. Different analytical and numerical calculations were performed to determine heat losses from simulant liquids to the surroundings, which played an important part in the experiment.
Ključne besede: nuclear power plant, severe accident, reactor core melt, lower plenum, heat flux focusing effect
Objavljeno v DKUM: 17.09.2019; Ogledov: 677; Prenosov: 118
.pdf Celotno besedilo (6,83 MB)

Analyses of the suspended-load sedimentation process and its dynamics in reservoirs with high daily oscillations
Helena Vrecl-Kojc, Bojana Dolinar, Roman Klasinc, Ludvik Trauner, 2008, izvirni znanstveni članek

Opis: The river water pumped into reservoirs with high daily oscillations, e.g. at pumping hydroelectric power plants, contains different amounts of suspended load depending on the time period and the riverćs discharge. This paper presents an analysis of the suspended-load sedimentation process that is based on the interaction between the sedimentation, i.e., the settling, velocity and the motion of the water. The settling velocity of spherical particles in the presence of a buoyancy force is a function of the particle size. Laboratory investigations of the suspended material from the river-watersamples have determined the ratio between the particle size and the concentration of suspended material with respect to the river discharge, the ratio between the concentration of suspended material in the water and the discharge, and the relationship between the concentration of suspended material and the discharge of water, which is for the first time expressed as an exponential function. The motion of the water in the reservoirs with high daily oscillations is solved by the three-dimensional modeling of the liquid streams. The evaluation of the results is presented for the case of the planned Kozjak pumping hydroelectric power plant on the River Drava.
Ključne besede: suspended load, water motion, sedimentation, sedimentation transport, pumped hydroelectric power plant, reservoir
Objavljeno v DKUM: 05.06.2018; Ogledov: 1377; Prenosov: 44
.pdf Celotno besedilo (348,17 KB)
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Intra-minute cloud passing forecasting based on a low cost iot sensor - a solution for smoothing the output power of PV power plants
Primož Sukič, Gorazd Štumberger, 2017, izvirni znanstveni članek

Opis: Clouds moving at a high speed in front of the Sun can cause step changes in the output power of photovoltaic (PV) power plants, which can lead to voltage fluctuations and stability problems in the connected electricity networks. These effects can be reduced effectively by proper short-term cloud passing forecasting and suitable PV power plant output power control. This paper proposes a low-cost Internet of Things (IoT)-based solution for intra-minute cloud passing forecasting. The hardware consists of a Raspberry PI Model B 3 with a WiFi connection and an OmniVision OV5647 sensor with a mounted wide-angle lens, a circular polarizing (CPL) filter and a natural density (ND) filter. The completely new algorithm for cloud passing forecasting uses the green and blue colors in the photo to determine the position of the Sun, to recognize the clouds, and to predict their movement. The image processing is performed in several stages, considering selectively only a small part of the photo relevant to the movement of the clouds in the vicinity of the Sun in the next minute. The proposed algorithm is compact, fast and suitable for implementation on low cost processors with low computation power. The speed of the cloud parts closest to the Sun is used to predict when the clouds will cover the Sun. WiFi communication is used to transmit this data to the PV power plant control system in order to decrease the output power slowly and smoothly.
Ključne besede: photovoltaic power plant, cloud passing forecasting, algorithm, sensor, Raspberry Pi, camera, wide-angle lens, optical filters, internet of things
Objavljeno v DKUM: 20.07.2017; Ogledov: 1653; Prenosov: 359
.pdf Celotno besedilo (8,15 MB)
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Maintenance supply chain for nuclear power plants : information technology support for human resources management
Andrej Androjna, Robert Bizjak, Bojan Rosi, 2009, izvirni znanstveni članek

Opis: The paper is looking at a case on IT support of HR management in a maintenance supply chain for nuclear power plants and analyzing a specific solution developed by NUMIP Ltd. The database NOS Data developed by NUMIP Ltd.has proved to be an efficient tool for the intended purpose and size of the current application. Yet there is a clear potential for improvement of the tool in the future, mainly related to direct electronic data exchange with customers and subcontractors, as well as to implementation of requirements of nuclear plants from different markets. The case study provides a description of a relatively complex requirement structure that applies to outsourced personnel working in maintenance activities in a nuclear power plant. The area is rather poorly covered in literature, hence the paper may be of interest to practitioners and students, as well as researchers.
Ključne besede: supply chain, maintenance, nuclear power plant, information technology, human resources
Objavljeno v DKUM: 05.06.2012; Ogledov: 1711; Prenosov: 53
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