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Accident Tolerant Fuel simulation loaded in advanced nuclear reactor during severe accident conditions
Hamřík, Lukáš ; Foral, Štěpán (referee) ; Mičian, Peter (advisor)
Tato diplomová práce se zaměřuje na paliva se zvýšenou tolerancí vůči haváriím, jež jsou považována za další krok ke zvyšování bezpečnosti provozu jaderných elektráren. Zpočátku jsou odhaleny slabiny v současnosti provozovaného palivového systému. Jsou popsány možnosti pokročilých paliv a jejich kategorizace, v návaznosti na jejich stav vývoje a problémy, kterým čelí před svým nasazením. Je zmíněna elektrárna APR1400 se svými systémy pro zmírnění následků havárie. Model APR1400 je využit k posouzení vlivu pokročilých materiálů pokrytí při těžké havárii. Stručně jsou představeny možnosti a schopnosti kódu MELCOR, který je schopen simulovat danou problematiku těžkých havárií. Je popsána implementace pokročilých materiálů pokrytí do programu MELCOR, společně se simulovanými scénáři. Na závěr jsou diskutovány výsledky získané ze simulací.
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Spent fuel pool accident simulation
Strieš, Jakub ; Foral, Štěpán (referee) ; Mičian, Peter (advisor)
The aim of the thesis is to provide a theoretical basis for simulating spent fuel pool accidents and to try to build a working model in the Melcor environment. The thesis is divided into four main parts. In the first part a description of the spent fuel pool is given. The processes that take place in nuclear fuel and thus lead to the formation of spent fuel are described. The reasons for the need to cool nuclear fuel after it has been in the reactor are described. For example, the generation of residual heat is described. This is followed by a description of the basic parts and purpose of a spent fuel pool. Structural parts, measuring systems or requirements for the pool itself are shown. Subsequently, an overview of accidents in spent fuel pools that have occurred in the past is also included in this chapter. Their causes and consequences are described, but especially their impact on the further development of nuclear safety, especially in the field of spent fuel pools. For both description and subsequent simulation, the two most studied ones, namely the loss-of-cooling failure and the loss-of-coolant failure, have been selected. The third section introduces the Melcor program which, is the main tool to create the simulation model. The chapter contains a basic description of the program as well as an introduction to the modules that are specifically designed for spent fuel pool simulations. The last part is a description of the model used, its creation, modification, problems in its creation and their solution. Finally, the results obtained are shown and described, together with a commentary to complete their understanding.
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Safety of the fuel stored in water pool
Mičian, Peter ; Novotný, Filip (referee) ; Foral, Štěpán (advisor)
This diploma thesis deals with storing the spent nuclear fuel and reviewing its safety. The theoretical part analyzes the processes taking place while the fuel is being used, such as fission, isotopic changes, fission gas release, cracking, swelling and densification of fuel pellet. The thesis is also focused on handling the spent fuel and on the way it makes from the reactor, through the spent fuel pool, the transportation, various kinds of storing, till the reprocessing and final deep geological repository. Furthermore, this part of the thesis briefly discusses computing code MCNP, its main characteristics, input files and using. The practical part of the work is focused on creating the model of the spent fuel pool located next to the nuclear reactor WWER 440/V213. This type was chosen, because it is the most used type of nuclear reactor in Czech Republic and Slovakia. With the help of the code MCNP, the multiplication factor of the main configurations of the fuel in the pool was calculated, and then the required safety regulations to ensure sufficient subcriticality, so its safety, were checked. Next, several analysis were performed using this model. These analyses were concerning the temperature of coolant, fuel and the use of various nuclear data libraries. In the future this model can be used to realize new analyses with new kinds of fuels, materials and data libraries.
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Nuclear Fuel Innovation
Mičian, Peter ; Zeman, Miroslav (referee) ; Katovský, Karel (advisor)
This bachelor thesis deals with the latest findings about nuclear fuel, especially fuels for pressurized water reactors. The thesis provides an overview of the latest research in the field of fuel cladding, which separates the fuel from coolant. Part is focused on burnable absorbers, which helps to reduce neutron flux during the first year of new fuel assembly. Furthermore, the thesis briefly discusses transmutation fuel cycles. the main empahsis is focused on ATF fuels, in the form of fuels with enhanced thermal conductivity. Develompment in this field could increase the safety and usage of the nuclear energy. The latest part is focused on applications of computational program FEMAXI-6 and analyze its outputs. This program deals with calculations of behavior of high-burnup fuel elements. As data for inputs were used real data from the nuclear power plant Dukovany.
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Methods of neutron detection
Arbeit, Vít ; Števanka, Kamil (referee) ; Mičian, Peter (advisor)
This bachelor thesis deal with neutrons, ways to detect them and with neutron detectors themselves. The theoretical part includes description of all principles by which it is possible to detect them and defines both already established neutron detectors and the latest type of detector. The practical part is focused on realization of Bonner spheres and the measurement of their properties on a neutron source 241Am-Be.
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Simulation and measurement of neutron field by Bonner spheres
Arbeit, Vít ; Šťastný, Ondřej (referee) ; Mičian, Peter (advisor)
The objective of this master’s thesis is introduction, explanation and practical demonstration of simulations conducted in program PHITS. The first part analyses neutrons and related issues regarding their detection as well as neutron sources. Next part is focused on program PHITS, both on it’s basic and advanced functions. Practical part of this thesis deals with the simulations of Bonner spheres and their responses to neutrons of different energies under different conditions. It also compares the results obtained through simulations with measured data.
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The state-of-of-art of research and design of nuclear fuel
Bílý, Lukáš ; Mičian, Peter (referee) ; Katovský, Karel (advisor)
This bachelor’s thesis deals with advanced nuclear fuels resistant to accidents. It focuses primarily on fuel cladding innovation. The aim was to select several concepts and then test them using the UwB1 program. The UwB1 program shows us how the multiplication factor changes during the nuclear fuel combustion process in the reactor. Based on the results, one concept was then selected.
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Experimental and calculational analyses of new generation nuclear fuels
Tioka, Jakub ; Mičian, Peter (referee) ; Števanka, Kamil (advisor)
The search for Accident tolerant fuels (ATF) which is the first part of this thesis is currently one of the most actual topics in the field of nuclear fuels. These fuels must be first successfully tested in operational and also accident conditions for their possible inclusion in commercial use. Following part of the thesis specifically focuses on the boiling crisis in nuclear reactors which can damage the nuclear fuel cladding. Therefore, it is necessary to know the critical heat flux value and the departure from nuclear boiling ratio. Calculations which determine critical heal flux value are placed in the practical part of the thesis. Calculations are compared with the data obtained during experiments. The ALTHAMC12 and the other correlations which are based on the previous measurements are used for the computational analysis.
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Present and Future Management and Utilization of Spent Nuclear Fuel
Hruškovič, Jan ; Mičian, Peter (referee) ; Katovský, Karel (advisor)
The Bachelor Thesis deals with spent nuclear fuel and possibilities of its management and utilization. The first chapter is focused on theoretical introduction, the nuclear fuel cycle is explained there together with radioactive waste and spent nuclear fuel. Possibilities of its management and utilization are listed, including some examples of practice around the world. The second chapter is focused on spent nuclear fuel in the Czech Republic. The reader is briefly acquainted with the history and present of nuclear energy in Czech Republic. Then the plan for the construction of a deep repository is described, including some requirements and criteria that need to be met and taken into account in planning and construction. The last chapter focuses on the attitude of countries that are significant in terms of nuclear energy to the management of spent nuclear fuel, including their brief introduction.
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