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Analysis of the innovated nuclear fuel with FEMAXI code
Čásar, Ondřej ; Novotný, Filip (referee) ; Foral, Štěpán (advisor)
This bachelor thesis deals with modification of source code of program FEMAXI 6 and subsequent analysis of composite nuclear fuel based on SiC admixture. First part introduces the entire open fuel cycle, from the start of the mining to the final disposal of the nuclear waste. The following part describes physical processes in the fuel, especially the processes associated with the low thermal conductivity of classical uranium oxide ceramic pellets, contains the description of the temperature calculations in the pellet and the analysis of the thermal conductivity coefficient including the influences affecting its size. One part of the thesis is an analysis of selected composite fuels increasing the thermal conductivity and introduction of a computational program for FEMAXI 6 nuclear fuel analysis, including its structure, implementation of equations and description of the input file. In the practical part, one can find a description of performed program modifications, comparison with other computational programs and analysis of possible composite nuclear fuel for Dukovany NPP.
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Benchmarks and test facilities of VVER reactors
Šimek, Ondřej ; Foral, Štěpán (referee) ; Vojáčková, Jitka (advisor)
The aim of this bachelor’s thesis is to describe the topic of benchmarks and test facilities for pressurized water reactors of the eastern concept VVER type. The theoretical part introduces the VVER type reactors, their history, the development of separate generations, including fundamental differences and parameters of the VVER type reactors being used so far. Next two chapters of the theoretical part focus on nuclear safety and security, describing the uppermost Czech authorities, which are SÚJB, MAAE and NEA. Furthermore, many terms concerning nuclear safety are explained in these two chapters. The next chapter is focused on deterministic safety analyzes, their classification, methods and purposes. The aim of this part is also to explain the verification and validation of computing codes. The next chapter offers insight into test facilities which are crucial for evaluation and testing of nuclear devices and computing codes. The last chapter of the theoretical part focuses on the VVER type reactor benchmarks. The practical part of this thesis presents the conversion of a single AER Benchmark FCM_001 using neutron physical code PARCS. The results are compared to the results of CRONOS computing code.
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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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Trends in nuclear fuel development
Takács, Gergő ; Števanka, Kamil (referee) ; Foral, Štěpán (advisor)
The aim of the bachelor thesis is to acquaint the reader with the differences between pressurized water reactors of the eastern and western type. It describes the differences in the materials used in the cladding and describes the concepts of individual fuel assemblies. It devotes a section to the various events that occur between the fuel and the cladding during the fission reaction. It also gives an overview of what the largest companies are dealing with, describes future trends in the development of nuclear fuel.
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Specifications in the heat calculation of electrothermal devices
Mikmek, Vladislav ; Foral, Štěpán (referee) ; Lázničková, Ilona (advisor)
This bachelor's thesis deals with the heat calculation of a resistance crucible furnace with emphasis on the influence of selected specifications. The whole process of the heat calculation is described. The calculation used in this thesis requires inputs as the kind of material of the batch or it's weight, the dimensions of the crucible and of the heating elements and others. The output of the calculation is the heat necessary to melt the batch, power needed by the crucible, the dimensions of the resistance spiral, permitted surface load of the spiral and the number of supports in the furnace to hold the heating elements. Parts of the canculation where there is possible to choose different methods to acquire needed values are also mentioned. The last chapter shows on a particular example of crucible furnace the influence of selected specifications on quantities dependent on these specifications. In selected parts of the calculation, that can be done by at least two diffent methods, is shown the influence of the choice on the partial result. In the case of a bigger differences of the results is shown even the influence on the subsequent parts of the calculation and final results. The contribution of the thesis is a summarization of the influences of the selected specifications on the results of the heat calculation. It also shows that some selected specifications have minor and other major influence on the calculation.
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Fabrication and calibration of thermocouples
Balák, Martin ; Svoboda, Josef (referee) ; Foral, Štěpán (advisor)
This thesis is focused on the creation of laboratory task. The first part describes the operating principle of the thermocouple and according to which the physical laws are working. The thesis also shows the main categories of the division of thermocouple. Next chapter explains the composition of thermocouple welder, its main components and how the process of welding thermocouple wire is under way. The last chapter of the theoretical part is focused on the calibration of thermocouples. This chapter explains what the calibration is and it also shows the examples of calibration on real devices. The first part of the practical section describes the construction of the laboratory product and what materials were used for the given construction. The following part deals with the electrical interior of the thermocouple welder. Electrical diagram is described and there is also the description of how to direct and regulate the supply voltage and how it reaches the clamps of the capacitor. Its charging is observed by measuring instrument (voltmeter). The thesis works with the proper welding procedure, its potential problems, and the correct method of welding because the weld must be in sufficient quality in order to pass the calibration. This work also shows how the welds should not look and what to do in case they do not look well. The second part of the practical section deals with the comparison of welded thermocouples tested on produced product and on SR80 UWO. The three pieces of thermocouples were welded on each of them. Their following comparison is the proof of the quality of the welding preparation. The last part of the second practical part is focused on the calibration of the thermocouple prepared thanks to the product.
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Accidents of light water reactors
Bejček, Patrik ; Novotný, Filip (referee) ; Foral, Štěpán (advisor)
This thesis deals with the description of primary and secondary circuit of nuclear power plant with reactor VVER-400. Moreover, this thesis describes nuclear safety, its particular factors, and also international nuclear event scale. It is followed by a description of companies playing a significant role in the field of nuclear safety and a close attention is paid to SÚJB. In a section dedicated to nuclear safety, the focus is on events which can occur in nuclear power plant. In addition, the accident Large Break LOCA is described in detail. The practical part deals with the description and instructions to simulator PCTran developed by Micro-Simulation Technology. In the last part, there is an analysis of selected parameters which are simulated in simulator PCTran, parameters simulated in simulator RELAP5 5 and also the calculation of the temperature parameters of fuel TVSA-T and their simulation.
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Accumulation of thermal energy using phase change materials
Mareček, Tomáš ; Foral, Štěpán (referee) ; Radil, Lukáš (advisor)
This thesis aims to study and observe an accumulation of thermal energy by phase change materials. First, it presents suitable materials for the accumulation of thermal energy and classifies them into three main groups - eutectics, inorganic substances and organic substances. The next part describes current available phase change materials and some methods of thermal analysis. There is a representative protocol for measuring selected samples at the end of the thesis.
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Nuclear Fuel and its Behavior during Burn-up
Matocha, Vítězslav ; Foral, Štěpán (referee) ; Katovský, Karel (advisor)
The point of this bachelor’s thesis is to characterize different types of nuclear fuels and their behaviour during the process of burning-up. Futher, basic types of nuclear reactors are mentioned, as well as their history and different kinds of nuclear fuels used in these reactors. Then there are pieces of information about fuel cycles and fuel burning-up. Furthermore, the thesis concentrates on the changes, which happen in the nuclear fuel during the process of burning-up, such as swelling and cracking. In its other parts, this bachelor’s thesis deals with fission products, mainly gas fission products are mentioned here. At the end of this thesis, a simple model of nuclear fuel burning-up is created. This model follows concentration of izotopes of uranium and plutonium during fuel burning-up.
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