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Simulated chemical accident associated with the release of phosgene
NOVÁK, Jan
The thesis entitled "Simulated Chemical Accident Associated with Phosgene Leak" focuses on the issue of disasters in general and specifically on chemical disasters associated with leakage of dangerous chemicals. The thesis consists of a theoretical and a practical part. The theoretical part of the thesis is divided into four subchapters. The first subchapter deals with accidents in general, and the classification thereof into natural and anthropogenic contingencies. The subject of the second chapter deals with specification of accidents that occur in the chemical industry. A special focus is given to causes of chemical accidents, among which there are anthropogenic (human factor) and technical causes as well as working conditions and organization of work. As regards classification, chemical accidents are divided into chemical accidents associated with leakage of dangerous chemicals, further accidents with leakage of radioactive substances and those involving oil leaks. With regard to the topic of the thesis, the third subchapter specifically focuses on characteristics of chemical accidents associated with leakage of dangerous chemicals. This is the key part of the theoretical basis of the thesis. The subchapter deals with causes, classification, development, characteristic effects and consequences of such accidents. Factors are also mentioned that affect the spread in the environment of dangerous chemicals leaked as the result of chemical accidents depending on a number of conditions. The fourth subchapter is linked to the preceding chapter in that it provides a brief characteristic of dangerous chemicals. A special focus is given to a comprehensive specification of phosgene. The core of the practical part of the thesis lies in the implementation of research consisting in simulation or modelling of a chemical accident associated with leakage of a selected chemical from a particular chemical plant. For the purpose of modelling phosgene was selected as the dangerous chemical. The company Synthesia, a. s. located in Pardubice, was chosen as the chemical plant in question. The practical part of the thesis aimed at modelling a chemical disaster associated with phosgene leak at Synthesia, a. s. The software tool TerEx, version 2.9.1. was used for simulation. Using this computer program a total of ten contingency scenarios were prepared involving phosgene leaks of different quantities as consequence of a chemical accident at Synthesia, a. s. Another aim of the practical part of the thesis was to assess risks following from the chemical accident. This assessment was made on the basis of the results of the TerEx program in the form of toxic exposure, recommended examination of toxic phosgene concentration within certain distance from the place of leakage, areas of necessary evacuation of the population, and last but not least time dependence of phosgene concentration and accumulated dose within distances of necessary evacuation of the population. The third and also the last aim of the practical part of the thesis was to assess impacts of this potential chemical accident on the health or lives of the population. The results of the modelled chemical accidents involving phosgene leak from Synthesia, a. s. showed that this contingency would especially impact health but not lives of the population. The phosgene concentrations showed only threshold levels (from 10 to 20 mg/m3) that would cause irritation of the eyes and the upper respiratory tract / nasopharynx. Even though the results of the research showed that no serious impacts on the health of the population should occur, the worst possible contingency scenario should always be considered in the event of such chemical accident.
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