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Possibilities of the external cooling of a pressure vessel in case of the accident with active zone melting
Hanuš, Jan ; Suk, Ladislav (referee) ; Martinec, Jiří (advisor)
The accident at the Fukushima Daiichi nuclear power plant has shown us that there may be situations where the applied technology will not be able to successfully cool the reactor core. These situations may occur when more elements such as supply of energy to power the pumps and diesel generators are destroyed for example by tsunami or earthquake, or other not expected natural disasters. The inability of the residual heat removal leads to the melting of core, relocation to the bottom of reactor pressure vessel (RPV) and failure of RPV. Result of this accident may be containment failure and leakage of fission products into the environment. One way to prevent this scenario may be a passive system called IVR (In-Vessel Retention) by using external cooling of RPV that retains melted core in. This system counts with flooding of RPV´s shaft by water. After natural circulation of water provides the heat transfers from the wall of RPV. The applicability of IVR for VVER 1000 reactors is still in the course of research. However it´s already clear that the submersion of RPV shaft by water will not sufficient. Other elements as suitable insulation and RPV coating which provides a more intensive heat transfer from the walls of RPV will be needed.
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The design of components for emergency cooling of reactor pressure vessel
Katzer, Milan ; Šen, Hugo (referee) ; Martinec, Jiří (advisor)
My thesis deals with the design of an experimental emergency cooling device of the reactor pressure vessel (RPV). It consists of two parts, the theoretical one and practical one. Different molten corium cooling methods in terms of their efficiency and comparison are introduced in the theoretical part. The design of an experimental emergency cooling device, which incorporates a model channel past the reactor pressure vessel , is presented in the practical part. The cooling device consists of a model channel past the reactor pressure vessel, condensator, which takes away the heat generated by the reactor pressure vessel and the pump of a secondary loop. Next, thermal and hydraulic calculations are given in this section. The conclusion is devoted to the evaluation of particular cooling technologies and their comparison in terms of nuclear and technical safety.
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Concept of a small nuclear reactor for the heat supply purposes
Bobčík, Marek ; Skála, Zdeněk (referee) ; Martinec, Jiří (advisor)
The objective of this diploma thesis is to assess the suitability of a small nuclear reactor for the purpose of heat supply in small towns and cities. First, all the heat demands of these towns and cities are analysed. Then, a small nuclear reactor to serve these needs is designed and a computational model for burn-up fuel is created. The thesis aims to propose a design of a new heat exchanger. Economic and environmental criteria are taken into account as well and including safety measures. The outcome of this thesis is an evaluation of the whole concept with respect to potential future implementation.
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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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The steam generator for ESFR reactor
Bátěk, David ; Martinec, Jiří (referee) ; Šen, Hugo (advisor)
This master thesis deals steam generator for ESFR (European Sodium Fast Reactor), which is heated by liquid sodium. In the beginning chapters, there are theoretic information about ESFR's parameters and its' comparison with ohter types of heat exchangers in nuclear reactors with the same principal (sodium as a coolant). Then designing part follows, which contents of introduction of calculations, option of material and conception of heater. Computational part on its own includes thermal, hydraulic and stress calculations and comparison with aspects in nuclear safety and security.
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The flange gasket modification of SG VVER 440 primary collector
Blažková, Eva ; Martinec, Jiří (referee) ; Šen, Hugo (advisor)
The aim of this thesis is to address issues concerning the sealing of the lid for the primary collector within the steam generator (SG) of the nuclear power plant VVER 440. These steam generators are sealed in the original design by nickel rings. Modifying the existing method of sealing by a new type of sealing material, primarily from expanded graphite, can significantly reduce the pressure in the sealing surface and also stress in bolts and flanged joints. The new solution of sealing between the joint of collector and the lid should extend the life of joints and thus the nuclear and technical safety. The text is divided into the theoretical and computational part. A principle of the SG, the SG design, and a description of the joint and lid are mentioned in the theoretical part. The computational part shows calculations of the new joint, the original one, and comparison of both solutions in terms of technical and nuclear safety. The work contains drawing of the new joint.
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The flange gasket modification of SG VVER 1000 primary collector
Pransperger, Jan ; Martinec, Jiří (referee) ; Šen, Hugo (advisor)
This thesis deals with the replacement of the lid gasket of the primary collector of the steam generator VVER 1000. Original sealing by nickel rings is replaced by kammprofile gasket with expanded graphite layers. The thesis compare the properties of both types of gaskets and the new and the original configuration of flange joint which have been calculated according to EN 1591. The results are compared and conclusions arising therefrom are presented. The work includes results of FEM analysis of the new configuration of the flange joint. There is also a description of the main components of the nuclear power plants VVER 1000 primary circuit in the introductory part which focused on the construction and operation of the steam generator and its primary collector.
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Energy supply of mountain cottage
Flöhsler, Tomáš ; Martinec, Jiří (referee) ; Pospíšil, Jiří (advisor)
The aim of this Graduation Thesis is to devise a system of energy supply intended to provide supply of electric and heat energy to a vacation property. The main feature of this energy supply project stands for a shift from mains power supply to alternative energy supply using renewable resources. The reason for this change is the fustiness of power lines and their negative effect on the surrounding landscape. Due to the fact that authorities did not permit renovation of these power lines, the only way to preserve the functionality of the vacation property is to secure its power supply by employing renewable resources. The vacation property (a mountain cottage) is located in Hrubý Jeseník Mountains, approximately 15 kilometers from the town of Šumperk. The thesis also contains a description of the way outlying settlements are currently supplied with energy, including the possibility of accumulation and a brief description of each electrical appliance’s power consumption. In the design itself, I calculated the necessary collector surface and analyzed the most effective collector placement. As for the wind energy system, I had to found the best spot to place the turbine. Last but not least, the thesis contains the technical-economical comparison of the proposed alternatives.
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