This paper describes the analytical work done by modelling and evaluating a thermal shock in a WWER-440 reactor pressure vessel due to an emergency case. An axial oriented semielliptical underclad/surface crack is assumed to be located in the core weld line. Threedimensional finite element models are used to compute the global transient temperature and stress-strain fields. By using a three-dimensional submodel, which includes the crack, the local crack stress-strain field is obtained. With a subsequent postprocessing using the j-integral technique the stress intensity factors KI along the crack front are obtained. The results for the underclad and surface crack are provided and compared, together with a critical discussion of the VERLIFE code.

This paper describes the analytical work done by modelling and evaluating a thermal shock in a WWER-440 reactor pressure vessel due to an emergency case. An axial oriented semielliptical underclad/surface crack is assumed to be located in the core weld line. Threedimensional finite element models are used to compute the global transient temperature and stress-strain fields. By using a three-dimensional submodel, which includes the crack, the local crack stress-strain field is obtained. With a subsequent postprocessing using the j-integral technique the stress intensity factors KI along the crack front are obtained. The results for the underclad and surface crack are provided and compared, together with a critical discussion of the VERLIFE code.

This graduation thesis deals with evaluation of power and coolant flow in reactor core. The first part is a description of nuclear power plant VVER 440. It is focused on parts important for transfer and utilize energy in regular operating of generating block. In the second part, the equations for calculation of power and coolant flow in reactor core are deduced. The last part is about designing the program for calculation of published values. There are specified requirements for the program and on the basis of this the source code is written. The parts of code are described. In conclusion of this part, the user's manual is work out. The program is on CD in the annexe.

The master's thesis deals with the analysis of source term of the spent nuclear fuel of the Dukovany Nuclear Power Plant in order to determine the proposals for the transfer of spent nuclear fuel to a deep geological repository in the Czech Republic. To introduce the reader into the issue are briefly described the main aspects, such as the development of the nuclear fuel used in the history of the Dukovany Nuclear Power Plant. These aspects have an influence on the final draft of the timetable. One of the important partial tasks is the processing of an estimate of the future range of spent nuclear fuel, which is based on the current ideas of company ČEZ, a.s. for the future direction of the fuel cycle at the Dukovany nuclear power plant. For the purposes of this work, the key data are the time dependencies of radioactivity and the development of residual heat in individual fuel assemblies. This data are calculated by the software called PAL440_R4, based on the prepared estimates of the spent nuclear fuel assortment. The calculated data are then edited and sorted by MS Excel. For the sake of completeness, the characteristic values and the time dependencies of the radioactivity and the development of residual heat in fuel assemblies. Final timetables for the transfer of spent nuclear fuel to a deep geological repository are processed in several variants, and their selection and application options are justified. For illustration are important parameters given in the form of tables and charts.

The main aim of this thesis is the model design and control the secondary circuit block VVER 440. The search part of my work is a description of the secondary circuit. In the first part of the calculation is performed for the rated secondary circuit. The second calculation part focuses on the calculation circuit of the secondary for the reduced, influenced by shutting down one steam generator.

This Master’s thesis focuses on calculation of power and temperature distribution in fuel assemblies of VVER-440 reactor at Dukovany Nuclear Power Plant. Theoretical section contains a brief description of VVER-440 technology, fuel and its development at Dukovany Nuclear Power Plant, basics of heat generation in nuclear reactors as well as an overview and categorization of computer codes, used for core calculations. Of these codes, the MOBY-DICK computer code is then described in depth, including its input and output files. The MOBY-DICK code is later on used for pinwise calculating power distribution of selected fuel cycles of defined units at Dukovany Nuclear Power Plant, with vizualization of output values for characteristic fuel assemblies. Results of this computation are then used for analysis, whether uneven power distribution in the core and heat generation gradient within fuel assemblies have any influence on measuring channel output temperatures, which is the pivotal part of this thesis.

Nuclear power plants provide about 11 percent of the world's electricity production. For fission process is uranium fuels used with varying percentage of enrichment 235U for most of nuclear reactors. Uranium reserves are reducing and their mining cost increases. Therefore, the thorium fuel is discussed as revolution fuel for current and future nuclear power plants. This diploma thesis deals with possibility of thorium fuel utilization at various types of nuclear reactors with a focus on light water reactors. The practical part of the thesis is focused on simulation and calculations of various uranium dioxide and thorium dioxide layers at the fuel rods. Model of WWER 440 reactor was developed for the calculations with the addition of thorium fuel. The model simulates burning out of fuel for 5 years, with monitoring of fuel behavior and tracking changes of each material. The thesis tries to define the suitable ratio and parameters of layers combination of uranium and thorium fuel. For these ratios and parameters the thesis tries to give sufficient amount of computational analyzes.