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Ionizing radiation behavior and shielding
Konček, Róbert ; Štefánik, Milan (referee) ; Katovský, Karel (advisor)
Ionizing radiation is radiation with particle energies greater than the energy needed to remove an outermost electron from an atom. Exposure to ionizing radiation causes damage to living tissue, and can result in detrimental mutations. Thus, ionizing radiation shielding is discipline of great practical importance. This thesis is concerned with its basic principles and methods. Firstly, it gives thorough account of four major classes of ionizing radiation - alpha and beta particles, gamma rays, and neutron radiation - and their peculiarities with respect to shielding. The next part contains description of mathematical model developed to assess and simulate interactions of radiation with matter. Finally, assignment for a laboratory exercise is presented.
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Ionizing radiation shielding simulation using MCNP code
Konček, Róbert ; Košťál,, Michal (referee) ; Katovský, Karel (advisor)
Radiation is defined as ionizing if it has enough energy to remove electrons from atoms or molecules when it passes through or collides with matter. This ability implies potentially detrimental effects on living tissue. Ionizing radiation shielding is therefore a discipline of great practical importance. The thesis builds upon the author's previous work on the topic and widens the scope of discussion with theoretical and practical issues of advanced shielding calculations. The theoretical part of the thesis describes several approaches to calculating fluence or absorbed dose at an arbitrary point in space. Point-kernel methods provide sufficiently accurate results for simpler shielding problems. In many practical cases, however, calculations based on the transport theory are necessary. There are two basic types of transport calculations: deterministic transport calculations in which the linear Boltzmann equation is solved numerically, and Monte Carlo calculations in which a simulation is made of how particles migrate stochastically through the problem geometry. Advantages and disadvantages of both methods are discussed. In the practical part are the results of radiation shielding calculations performed with a major Monte Carlo code - MCNP6, compared with those obtained in the experiments, which were carried out at the Ionizing Radiation Laboratory at Department of Electrical Power Engeneering, FEEC BUT. The experiments consisted of placing a cobalt-60 radioisotope source at three different positions inside a lead collimator, and counting pulses with two different scintillation detectors positioned in front of the opening of the collimator, alternately with or without lead shield located between the source and the used detector. Agreement of the calculations and the data from the measurements is reasonable, given the inherent uncertainties of the experimental set-up. Performed sensitivity analysis shows relative importances of different parameters used as inputs in simulations, such as densities of materials, or dimensions of the scintillation crystals. Annotated MCNP input files used for simulation are also part of the thesis.
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Ionizing radiation behavior and shielding
Konček, Róbert ; Štefánik, Milan (referee) ; Katovský, Karel (advisor)
Ionizing radiation is radiation with particle energies greater than the energy needed to remove an outermost electron from an atom. Exposure to ionizing radiation causes damage to living tissue, and can result in detrimental mutations. Thus, ionizing radiation shielding is discipline of great practical importance. This thesis is concerned with its basic principles and methods. Firstly, it gives thorough account of four major classes of ionizing radiation - alpha and beta particles, gamma rays, and neutron radiation - and their peculiarities with respect to shielding. The next part contains description of mathematical model developed to assess and simulate interactions of radiation with matter. Finally, assignment for a laboratory exercise is presented.
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Ionizing radiation shielding simulation using MCNP code
Konček, Róbert ; Košťál,, Michal (referee) ; Katovský, Karel (advisor)
Radiation is defined as ionizing if it has enough energy to remove electrons from atoms or molecules when it passes through or collides with matter. This ability implies potentially detrimental effects on living tissue. Ionizing radiation shielding is therefore a discipline of great practical importance. The thesis builds upon the author's previous work on the topic and widens the scope of discussion with theoretical and practical issues of advanced shielding calculations. The theoretical part of the thesis describes several approaches to calculating fluence or absorbed dose at an arbitrary point in space. Point-kernel methods provide sufficiently accurate results for simpler shielding problems. In many practical cases, however, calculations based on the transport theory are necessary. There are two basic types of transport calculations: deterministic transport calculations in which the linear Boltzmann equation is solved numerically, and Monte Carlo calculations in which a simulation is made of how particles migrate stochastically through the problem geometry. Advantages and disadvantages of both methods are discussed. In the practical part are the results of radiation shielding calculations performed with a major Monte Carlo code - MCNP6, compared with those obtained in the experiments, which were carried out at the Ionizing Radiation Laboratory at Department of Electrical Power Engeneering, FEEC BUT. The experiments consisted of placing a cobalt-60 radioisotope source at three different positions inside a lead collimator, and counting pulses with two different scintillation detectors positioned in front of the opening of the collimator, alternately with or without lead shield located between the source and the used detector. Agreement of the calculations and the data from the measurements is reasonable, given the inherent uncertainties of the experimental set-up. Performed sensitivity analysis shows relative importances of different parameters used as inputs in simulations, such as densities of materials, or dimensions of the scintillation crystals. Annotated MCNP input files used for simulation are also part of the thesis.
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