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Experimental Investigation of Accelerator Driven Nuclear Reactors for Thorium Based Nuclear Power
Zeman, Miroslav ; ČR,, Milan Štefánik, UJF AV (referee) ; Katovský, Karel (advisor)
The Master Thesis deals with the use of thorium nuclear fuel in accelerator driven systems. Basic principle of ADS, present situation and future possibilities are described in this work. The main goal of the work is determination of neutron flux in spallation target QUINTA. In December 2013, an experiment was performed at Joint Institute for Nuclear Research, Dubna. Samples of cobalt, situated at different positions in QUINTA target, were irradiated in secondary neutron field generated by deuteron beam of energies 2 AGeV and 4 AGeV and beam of C-12 with energy 2 AGeV. The samples were measured with the use of germanium semiconductor detectors and analysed using gamma-ray spectrometry. Reaction rates of Co-59 products were determined. Neutron flux was determined in setup QUINTA on the base of experimental reaction rates. Experimental reaction rates were compared with calcula1tion of MCNPX code.
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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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Photopolymerization kinetics of dimethacrylate dental resin
Vaněk, Martin ; Bystřický, Zdeněk (referee) ; Poláček, Petr (advisor)
Aim of magister´s thesis was to study reaction kinetics of dental materials. Thesis was focused on dimethacrylate dental polymers, which are for example used for dental restoration, tooth repair and creating now teeth. First part of the thesis concentrates on influence of molar ratio on reation kinetics by addition of other monomer to polymer resin. Second part concentrates on influence of addition of additive silica on reaction kinetics of polymerization. Essential variables know as a polymerization ratio, conversion, gel point, glass transition temperature and storage modulus were studied. Firstly, polymerization ratio and conversion were observed by differential scanning calorimetry (DSC). Secondly rheology was observed by photoreometr. Finally, glass transition temperature and storage modulus were observed by dynamic mechanical analysis (DMA). Behaviour changes caused by addion of monomer or filler point out decrease of polymeration ratio and converstion. Same behaviour was observed by short exposure. In order to established network formation, values of gel point increased by higher concentration of monomer or filler. Glass transition temperature and storage modulus measured by DMA were evaluated. Those valuables had variable tendency due to monomer acting like filler at higher concentration. Also contradictory impact of different material conversion and filler concetration was discussed.
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Accelerator driven nuclear reactor neutron field parameters determination
Zemčíková, Kristína ; Šťastný, Ondřej (referee) ; Katovský, Karel (advisor)
The master thesis deals with calculation of neutron field parameters in systems controlled by an accelerator called the Accelerator Driven System (ADS). Firstly physical principle is described, along with its parts as well as the history and present of ADS projects worldwide. Subsequently, neutron activation analysis and gamma spectrometry are described in more detail. The experiment on AmBe neutron source and on Microtron MT25 is presented in the experimental part. Lastly, the reaction rates are calculated.
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Comparison of reaction rate in children diagnosed with ADHD and common population of the same age
Kovařovic, Vojtěch ; Nováková, Tereza (advisor) ; Vomáčková, Helena (referee)
Title: Differences in reaction rate in children with ADHD and the general population of the same age. Problem definition: ADHD is a neuropsychological disorder occurring in part of the pediatric population (5-8%). The scientific public mentions the existence of the so-called hyperfocus, ie the ability to significantly concentrate in children diagnosed with ADHD, especially in the case of these children being interested in the task. Methodologically correctly compiled and performed testing of the reaction rate of these children could confirm or refute this assumption. Aims: The aim of the work is to find out whether and possibly what effect the diagnosis of ADHD in children has on the reaction rate. Hypotheses: H1: The reaction rate in individuals with ADHD will be on average the same or higher than in individuals of the same age of the healthy population. H2: The difference between the individual experiments will be greater in children with ADHD than in individuals of the same age of the healthy population. H3: The individual with fastest reaction ability with ADHD will have the same or better result as the individual with the fastest reaction of the same aged healthy population. Methods: Testing for the purposes of this diploma thesis took place in the ROSA center. 12 probands in the tested group...
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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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Photopolymerization kinetics of dimethacrylate dental resin
Vaněk, Martin ; Bystřický, Zdeněk (referee) ; Poláček, Petr (advisor)
Aim of magister´s thesis was to study reaction kinetics of dental materials. Thesis was focused on dimethacrylate dental polymers, which are for example used for dental restoration, tooth repair and creating now teeth. First part of the thesis concentrates on influence of molar ratio on reation kinetics by addition of other monomer to polymer resin. Second part concentrates on influence of addition of additive silica on reaction kinetics of polymerization. Essential variables know as a polymerization ratio, conversion, gel point, glass transition temperature and storage modulus were studied. Firstly, polymerization ratio and conversion were observed by differential scanning calorimetry (DSC). Secondly rheology was observed by photoreometr. Finally, glass transition temperature and storage modulus were observed by dynamic mechanical analysis (DMA). Behaviour changes caused by addion of monomer or filler point out decrease of polymeration ratio and converstion. Same behaviour was observed by short exposure. In order to established network formation, values of gel point increased by higher concentration of monomer or filler. Glass transition temperature and storage modulus measured by DMA were evaluated. Those valuables had variable tendency due to monomer acting like filler at higher concentration. Also contradictory impact of different material conversion and filler concetration was discussed.
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Experimental Investigation of Accelerator Driven Nuclear Reactors for Thorium Based Nuclear Power
Zeman, Miroslav ; ČR,, Milan Štefánik, UJF AV (referee) ; Katovský, Karel (advisor)
The Master Thesis deals with the use of thorium nuclear fuel in accelerator driven systems. Basic principle of ADS, present situation and future possibilities are described in this work. The main goal of the work is determination of neutron flux in spallation target QUINTA. In December 2013, an experiment was performed at Joint Institute for Nuclear Research, Dubna. Samples of cobalt, situated at different positions in QUINTA target, were irradiated in secondary neutron field generated by deuteron beam of energies 2 AGeV and 4 AGeV and beam of C-12 with energy 2 AGeV. The samples were measured with the use of germanium semiconductor detectors and analysed using gamma-ray spectrometry. Reaction rates of Co-59 products were determined. Neutron flux was determined in setup QUINTA on the base of experimental reaction rates. Experimental reaction rates were compared with calcula1tion of MCNPX code.
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Experimental Determination of Neutron Room Background at the NPI Cyclotron U-120M
Štefánik, M. ; Bém, Pavel ; Honusek, Milan ; Katovsky, K. ; Majerle, Mitja ; Novák, Jan ; Šimečková, Eva
During the operation of external neutron generators of the Nuclear Physics Institute of The Academy of Sciences of the Czech Republic, the neutron room background is produced in cyclotron hall. To assess this effect, the neutron room background was measured using the activation method of dosimetry foils. To unfold the background spectrum from the set of measured reaction rates, the method of spectrum description by the special analytical function was employed.
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