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Experimental Investigation of the Neutron Field in an Accelerator Driven Subcritical Reactor
Zeman, Miroslav ; Janda,, Jiří (referee) ; Chudoba,, Petr (referee) ; Katovský, Karel (advisor)
This dissertation focuses on irradiations of a spallation set-up consisting of more than half a ton of natural uranium that were executed by a 660 MeV proton beam at the Joint Institute for Nuclear Reserch in Dubna. Two types of irradiations were arranged: with and without lead shielding. Both types were arranged with threshold activation detectors (Al-27, Mn-55, Co-59, and In-nat) located throughout the whole set-up both in horizontal and vertical positions and activated by secondary neutrons produced by spallation reaction. The threshold activation detectors were analysed by the method of gamma-ray spectroscopy. Radionuclides found in the threshold detectors were analysed and reaction rates were determined for each radionuclide. Ratios of the reaction rates were determined from irradiation of the set-up with and without lead shielding. Subsequently, the neutron spectra generated inside the spallation target at different positions were calculated using Co-59 detector. The experimental results were compared with Monte Carlo simulations performed using MCNPX 2.7.0.
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Investigation of Thorium Utilization in Accelerator Driven Nuclear Reactors
Král, Dušan ; ČR, Petr Chudoba, ÚJF AV (referee) ; Zeman, Miroslav (advisor)
This thesis deals with the idea of using accelerator driven systems for thorium transmutation into the fissile material, which can be utilized in the accelerator driven systems and in thermal nuclear reactors. Thorium occurs on Earth only in fertile isotope Th-232. It can be converted to fissile U-233 by neutron capture and subsequent beta decay. The experimental part handles the data measured by the irradiation of four thorium samples by the secondary neutrons in the QUINTA spallation target, which was irradiated with 660~MeV protons. Reaction rates for the fission and spallation products were estimated using gamma spectroscopy and activation techniques. Furthermore, Pa-233 production rates were also determined in all experimental samples. Pa-233 and fission production rates were calculated in all experimental samples using the MCNPX transport code and evaluated nuclear data for high-energy reactions. The experimental results are of a great importance for the future investigation of thorium in the accelerator driven system concept, validation of Monte-Carlo based calculation codes and validation of high-energy nuclear models.
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The preliminary ruling
Chudoba, Stanislav ; Sedláček, Miroslav (advisor) ; Smolík, Petr (referee)
The preliminary ruling The subjects of thesis research are preliminary rulings considering the Czech civil proceedings and preliminary rulings submitted to the Court of Justice of the European Union. The thesis is designed to analyze legal changes made to the preliminary rulings with emphasis on the case-law. The introductory historical part of this thesis describes the then Roman law institute called praeiudicium, in which the beginnings of the development of the current form of the preliminary rulings can be observed. Later on, the attention of the thesis is shifted towards preliminary rulings in the legal order of the Czech Republic. After the opening determination of the term, the following chapters begin to focus on the nuances of the terminology of this procedural institute, position of the preliminary ruling in the judgment or explaining the differences between material and procedural preliminary rulings. The main chapter is centered around the boundness of the court by existing decisions regarding the specific question. This part is followed up by the explanatory breakdown of the law in force. The next chapters of the thesis discuss the assessment of the preliminary rulings that have not been ruled yet. The chapters also examine facultative and obligatory suspension of the proceeding...
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By-laws of a bank
Chudoba, Martin ; Liška, Petr (advisor) ; Elek, Štefan (referee)
of the Thesis "By-laws of a bank" My thesis is dedicated to the by-laws of a bank in the Czech Republic, which are often considered to be the most important document of not only a bank, but also a joint-stock company in general. The main goal of this work is to map and describe the present situation concerning the legal regulation of by-laws of a bank in the domestic law. The first chapter briefly outlines the historical development of the corresponding regulation. In a retrospective manner, we are introduced to acts relevant to the bank's by-laws before the contemporary legal framework, consisting of Act No. 513/1991 Coll. (the Commercial Code) and Act. No. 21/1992 Coll. (on Banks), was adopted. The secondary purpose of this chapter is to familiarize the reader with the statutory enactment of banking industry during the period of communism since 1948. In the second chapter, evolution of the term "bank" itself in the context of Act on Banks is explained. The difference between legal definition and factual meaning of a bank is emphasized. The third and the most comprehensive part describes the by-laws of a bank themselves in the view of both above mentioned acts. By-laws' significance, character, processes of adoption and amendments, validity, force and other aspects are discussed along with their...
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Photon strength functions in 162Dy from two-step gamma cascade measurement
Chudoba, Petr ; Krtička, Milan (advisor) ; Knapp, František (referee)
Photon strength functions quantities, which describe deexcitation of nucleus by emiting gamma rays within statistical model of the nucleus. Information about these quantities can be gained from study of two-step gamma cascades. The thesis is focused on processing of experimental data from measurement of these cascades in 162Dy nucleus. Data were acquired using experimental set-up istalled on the research reactor in Řež near Prague. In the experiment the 161Dy targed was bombarded by thermal neutrons. Following gamma deexcitation of 162Dy nucleus was measured by coincident spectrometer composed of two semi-conductor detectors. The aim of the thesis is to perform energy and efficiency calibration and to process experimental data into the form of two-step gamma cascades spectra. In adition, a comparsion of the two-step cascades spectra with the outcome of simulations of a few basic models of photon strength functions is made.
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Study of reaction cross-sections important for advanced nuclear systems
Chudoba, Petr ; Wagner, Vladimír (advisor) ; Krása, Antonín (referee) ; Krtička, Milan (referee)
The doctoral thesis is focused on measurements of neutron cross-sections mainly cross-sections of (n,xn) threshold reactions. With the dawn of advanced nuclear systems such as fast reactors of GenIV, accelerator driven system or even fusion reactors, monitoring of fast neutron fields will gain on importance. The activation detectors are one of the viable options how to monitor these neutron fields and (n,xn) reactions would be one of the best options how to do such monitoring. There is one condition though. We need to have good cross- section data in high neutron energy region. Unfortunately, the current situation is rather bad. There is only a small amount of reliable data for neutron energies above 20 MeV and with increasing energy, the situation gets only worse. For this reason, we measure the cross-sections of (n,xn) reactions on perspective materials such as yttrium, gold and tantalum with neutron energies from 17.4 up to 94 MeV. In this thesis, the measurements together with motivation and methodology are described. Obtained results are in agreement with existing data. Severe discrepancies were observed between the predictions and experimental data for high order (n,xn) reactions. This problem is discussed and solved. The results in this region are in form of cross-section values and also...
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Environmental protection through integrated permitting
Chudoba, Petr ; Sobotka, Michal (advisor) ; Humlíčková, Petra (referee)
The introduction of an IPPC proceedings into Czech law has been executed through implementation of requirements of Directives enacted at the level of European Communities and subsequently at the level of European Union and Czech republic was obliged to implement the content of the Directives by being a member state of those international organizations. During the IPPC proceedings of application for an integrated permit the participants and other subjects who can express their statement on the application a chance to influence the final content of an integrated permit. This influence subsequently might change the conditions of operation of large industrial and agricultural compounds and the emission limits binding for the operator of such compounds. This thesis focuses on an evaluation of possibilities to protect the environment through IPPC during the proceedings of application for an integrated permit, through managing the way of establishing the emission limits within the obligatory conditions of operation and through an influence of preceding proceeding and subsequent proceedings, which are part of allowing the intended activity of the operator.
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Consumer credit.
Chudoba, Jan ; Liška, Petr (advisor) ; Eichlerová, Kateřina (referee)
This diploma thesis analyzes legislation governing consumer credit. In the recent past, a notable development has occurred in this particular area of consumer protection, especially in the field of European legislation. This development has also been reflected in the Czech legal system due to the necessity of transposing European directives. This diploma thesis describes the development of consumer credit legislation at European level starting with Directive 87/102/EHS and also by the Consumer Credit Directive and the Mortgage Credit Directive, which is the last legislative act of the Union legislator in this area and in the domestic legal system starting with Act 321/2001, following with Act 145/2010 and finishing with the current legislation by the Consumer Credit Act. The Consumer Credit Act contains a comprehensive regulation of the activities of providing and mediating consumer credit, regulation of entities operating on the consumer credit market as well as rights and obligations in the provision and mediation of consumer credit. The first chapter defines terms needed to understand consumer credit issues such as consumer, credit and consumer credit terms. The first chapter also contains a basic description of the issue of consumer protection, which, as a legal area, covers all areas of legal...
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Use of activation detectors for neutron field measurement in models of ADTS
Chudoba, Petr
Accelerator driven transmutation systems could be a solution to the problem with long-lived nuclear waste and opening the way to thorium fuel cycle. Due to intensive neutron source based on spallation reaction are these systems very litle dependent on the arrangement of the core and fuel quality. These systems can transmute the spent fuel, eventually 232Th or 238U without affecting maintenance of fission reaction. Additionally subcritical blanket ensures high safety. For these systems it is necessary to know the cross sections of reactions of fast neutrons produced in the spallation reaction with different materials. This data is necessary not only for the selection of appropriate construction materials, but also for creation of programs simulating accelerator driven transmutation systems. This thesis is focused on the experimental determination of cross sections of reactions 89Y(n,2n)88Y and 89Y(n,3n)87Y with neutron energies from 17,6 to 33,6 MeV. Yttrium is analyzed for its (n,xn) threshold reactions, which makes it appropriet activation detector for study of the neutron fields in model configurations of accelerator driven transmutation systems. The obtained cross sections are unique, in that so far there are no experimental data for used neutron energies. Powered by TCPDF (www.tcpdf.org)
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