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Performance of Composite Nuclear Fuels during Normal Operation and Nuclear Reactor Accidents
Foral, Štěpán ; Valach,, Mojmír (referee) ; Haščík,, Ján (referee) ; Katovský, Karel (advisor)
Tato práce se zabývá oblastí kompozitních jaderných paliv založených na UO2 . V práci je vyjmenováno několik materiálů vhodných jako aditivum ty jsou srovnány z několika různých hledisek. Byla vybrána kombinace UO2 + SiC pro detailní analýzu. Bylo zjištěno, že tato kombinace vykazuje dobré parametry v průběhu normálního provozu. Uvolňování plynných produktů štěpení je nižší společně s tepelně-mechanickým namáháním. Nicméně, je potřeba vyvinout nové modely chování kompozitních paliva. Analýza havárie blízké typu LOCA ukazuje, že palivo UO2 + SiC vykazuje poněkud lepší parametry ve srovnání s UO2 . Centrální teplota je nižší a mechanické namáhání je rovněž nižší. Na druhou stranu, analýza RIA havárie ukázala možné potíže. Například, zvýšená tepelná vodivost byla pravděpodobným důvodem zvýšené maximální teploty pokrytí a umocněné krize varu. Toto zjištění se pravděpodobně týká všech paliv založených UO2 , které mají zvýšenou tepelnou vodivost pomocí dopantů.
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Approach to the nuclaer safety of the 3rd generation nuclear reactors
Pavlíček, Michal ; Kolář, Jaroslav (referee) ; Kolář, Jaroslav (referee) ; Matal, Oldřich (advisor)
The main target of the master´s thesis is reviewing the generation III nuclear reactors in term of the nuclear safety. At first we have to learn some theory of the nuclear safety in order to understand safety systems of the generation III nuclear reactors. Therefore the thesis is divided into two parts. Legislative and technical approaches to nuclear safety are mentioned in the first part. Regulatory bodies, whose task is to supervise nuclear safety in the nuclear power plants, belongs to the legislative approaches. There are defined terms such as defence in depth, redundancy, diversity, etc. There are mentioned methods to assessing nuclear safety – deterministic and probabilistic methods, especially probabilistic methods, for which a simple example is provided. There are also mentioned active and passive safety systems and their significance for nuclear safety and inherent safety too. There is an example of the function of the active and passive safety systems of the EDU nuclear power plant in conclusion of this issue. The second part deals with description of the selected nuclear reactors in context of the construction of the new units of nuclear power plant in Temelín. The nuclear reactors from companies, which applied for the public tender opened by ČEZ, a. s., for the construction of the ETE 3+4. Thus, the nuclear reactor MIR-1200 by ATOMSTROYEXPORT (Russian Federation), the nuclear reactor AP1000 by WESTINGHOUSE (USA) and the nuclear reactor EPR by AREVA (France) are taken into account . Comparison of the generation II and these generation III+ nuclear reactors necessarily belongs to this master´s thesis. These the generation III+ nuclear reactors are compared with the nuclear reactor VVER 440 (EDU) and in particular with the nuclear reactor VVER 1000, which is operated in the nuclear power plant Temelín. The final chapter contains generally appraisal of the whole problem.
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Application possibilities of systems with heat accumulation in nuclear power
Sklenářová, Lenka ; Maar, Tomáš (referee) ; Martinec, Jiří (advisor)
This dissertation covers the application of heat accumulation systems in nuclear power engineering, namely in nuclear power plants. It is mainly a case of passive emergency systems, whose task is to accumulate the heat produced in the reactor’s active zone and in spent fuel pools during DBA (design-basis accidents) or beyond DBA. A particular example of heat accumulation is steam condensation after LOCA (loss of coolant accident). The primary circuit steam leakage increases containment pressure and has to be decreased by the steam condensation. This thesis deals with a theoretical substitute for ice condensers, which are used as a passive safety measure in some nuclear power plants. The substitute involves a choice of an alternative material, whose melting temperature (for heat accumulation) is closer to nuclear power plant operating temperatures. The other part of the dissertation discusses heat accumulation in spent fuel pools in case of all cooling systems failure.
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LOCA Energy Performance Study for Simulation of Heavy Accident at NPP
Zemčíková, Kristína ; Andrle,, Karel (referee) ; Mastný, Petr (advisor)
This bachelor’s thesis studies the energy performance of the LOCA device used for the simulation of accidents at nuclear power plants, which can be found at the CV Řež research centre. LOCA stands for Loss of Coolant Accident, which is kind of serious accident that may occur at NPPs. During the accident, the coolant is assumed to be leaking due to a fissure in one of the main pipes. The unique LOCA device at the research centre simulates this accident and is used for testing important components utilised at nuclear power plants. This thesis describes the LOCA device and attempts to determine its energy consumption over the course of a 10-day experiment. By leveraging the consumption curve of the research centre, possible operational optimisations applicable to this LOCA device technology will be proposed.
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Probabilistic safety assessment of operation
Jordánová, Petra ; Mladý, Ondřej (referee) ; Kotek, Luboš (advisor)
This thesis deals with the method of modelling event trees and fault trees within the probabilistic safety assessment at the Dukovany nuclear power plant. In the first part, probabilistic safety assessment is presented, along with a description of the used analyses, specifically ETA and FTA, and the software used for development of probabilistic models at nuclear power plants in the Czech Republic. Then Large LOCA accident is described, for which a pilot model is developed in the second part of this thesis. The main aim of this thesis is a replacement of the original modelling method with a new modelling. The presented method focuses, in addition to a development of event trees and fault trees, primarily on the substitution of previously used house event for initiating events. In order to prove correctness of the created model, the cut sets from both models are compared. The benefit of the work is the elaboration of a pilot model that utilizes a different modelling method. Thanks to the presented modelling method, the existing number of event trees can be significantly reduced, and manual setting of house events can be removed. This approach simplifies the work with the model and shortens the calculation time.
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Severe accidents of third generation pressurized water reactors
Nečas, Karel ; Foral, Štěpán (referee) ; Černý, Tomáš (advisor)
The bachelor thesis focuses on the development of global nuclear energy. It clearly describes the development and division of nuclear facilities used for electricity production. The theoretical part of the thesis describes the division of nuclear facilities according to the development generations, the types are discussed in terms of technology and principle of operation. The operating conditions of nuclear reactors are described in detail, with emphasis on emergency conditions. The next part of the thesis focuses on the LOCA accident type for third generation pressurized water reactors. This thesis also includes an analysis of different approaches od the computation codes used for modelling various conditions of the nuclear power plants. The practical part of the bachelor thesis describes nuclear reactor APR1400. It provides its elementary parameters. The calculation code MELCOR was used for modelling this type of the nuclear reactor. The sensitivity analysis of the severe accident was performed using selected parameters. This analysis describes the influence of these parameters on the hydrogen production, the process of damaging of the active zone, and the reactor vessel melting time.
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Performance of Composite Nuclear Fuels during Normal Operation and Nuclear Reactor Accidents
Foral, Štěpán ; Valach,, Mojmír (referee) ; Haščík,, Ján (referee) ; Katovský, Karel (advisor)
Tato práce se zabývá oblastí kompozitních jaderných paliv založených na UO2 . V práci je vyjmenováno několik materiálů vhodných jako aditivum ty jsou srovnány z několika různých hledisek. Byla vybrána kombinace UO2 + SiC pro detailní analýzu. Bylo zjištěno, že tato kombinace vykazuje dobré parametry v průběhu normálního provozu. Uvolňování plynných produktů štěpení je nižší společně s tepelně-mechanickým namáháním. Nicméně, je potřeba vyvinout nové modely chování kompozitních paliva. Analýza havárie blízké typu LOCA ukazuje, že palivo UO2 + SiC vykazuje poněkud lepší parametry ve srovnání s UO2 . Centrální teplota je nižší a mechanické namáhání je rovněž nižší. Na druhou stranu, analýza RIA havárie ukázala možné potíže. Například, zvýšená tepelná vodivost byla pravděpodobným důvodem zvýšené maximální teploty pokrytí a umocněné krize varu. Toto zjištění se pravděpodobně týká všech paliv založených UO2 , které mají zvýšenou tepelnou vodivost pomocí dopantů.
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LOCA Energy Performance Study for Simulation of Heavy Accident at NPP
Zemčíková, Kristína ; Andrle,, Karel (referee) ; Mastný, Petr (advisor)
This bachelor’s thesis studies the energy performance of the LOCA device used for the simulation of accidents at nuclear power plants, which can be found at the CV Řež research centre. LOCA stands for Loss of Coolant Accident, which is kind of serious accident that may occur at NPPs. During the accident, the coolant is assumed to be leaking due to a fissure in one of the main pipes. The unique LOCA device at the research centre simulates this accident and is used for testing important components utilised at nuclear power plants. This thesis describes the LOCA device and attempts to determine its energy consumption over the course of a 10-day experiment. By leveraging the consumption curve of the research centre, possible operational optimisations applicable to this LOCA device technology will be proposed.
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