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Cs-137 content monitoring by spectrometric measurement in soil
LEPIČ, Daniel
The aim of the thesis is to compare the results from in situ spectrometry and laboratory determination of the area activity of Cs-137 in samples taken from uncultivated soils. To fulfil the goal, the research question has been determined: Are the results from in situ measurement of the area activity of Cs-137 in uncultivated soil comparable with the results from laboratory measurement of collected soil samples? The theoretical part of the work has been written based on research of book publications, foreign scientific articles and electronic sources, which deal with the issue of radioactivity and its impact on the environment and the principle of semiconductor gamma spectrometry. The practical part of the work deals with the spectrometric measurement using in situ method and the laboratory determination of the area activity of Cs-137 in the soil samples using a semiconductor gamma spectrometer. The measurement and the soil sampling took place in the territory of the Šumava National Park and its adjacent areas in Pilsen Region. There were selected five locations (Nová Hůrka, Prášily, Srní, Nový Brunst and Hadí vrh). By in situ spectrometric measurement the highest values were determined of the area activity of Cs-137 in the location Nová Hůrka (19526 Bq / m2) and the lowest in the location Hadí vrh (5398 Bq / m2). The spectrometric measurements of the soil samples in the laboratory revealed the highest values of the area activity of Cs-137 in the sample from the location Nová Hůrka (10000 Bq / m2) and the lowest values of Cs-137 in the location Hadí vrh (2060 Bq / m2). The contribution of this work is the comparison of in situ spectrometric measurement with the measurement of taken soil samples using the gamma semiconductor spectrometer. The results of this monitoring can provide data on the radiation situation in individual locations in Šumava. By the comparison of the results of the area activity of Cs-137, there has been found a correlation between in situ spectrometric measurements and the laboratory measurements of the soil samples. The results of the area activity of Cs-137 are in an order of magnitude comparable. The differences between the results are probably caused by the measurement conditions.
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A comparison of the radiometers which are used by the Fire Rescue Service of the Czech Republic
PETRŮV, Josef
Fire Rescue Service is the basic component of an integrated rescue system, with high working demands placed on their activity. The number of activities firefighter units perform is extensive; especially great attention is paid to interventions with eventual incidence of ionizing radiation. Ionizing radiation is not possible to detect by human senses, but is possible to detect with special instruments. Identification of ionizing radiation is not simple; it requires certain amount of time, professional knowledge, and facilities. To prevent irradiation of people who are present at an intervention place and also people who intervene, the units of Fire Rescue Service of the Czech Republic are equipped with the portable ionizing radiation detectors according to Conception of Chemical Service. These are namely DC-3E-98, DC-3H-08 and Ultra- Radiac (U-RAD 115). The instruments are constructed to detect radiation. The goal of the thesis is to compare instruments in terms of the accuracy and speed of measurement and to assess suitability of use of the instruments by fire protection units of the Czech Republic, economic comparison and the practicability of the instruments. DC-3E-98 is hand contamination detector used for surface contamination and dose rate meter that dates with its design back to 1970s of the series DC-3 used for operative radiological survey. It was developed and manufactured in today's nonexistent plant Zavod mechanizace a automatizace Ostrov nad Ohri. This device has been used until recent days after had been modified at the end of 1990s and because of needs to follow Act on Metrology. It is consisting of two parts, separate instrument and removable probe. Both parts create easily demountable unit allowing carrying out measuring by only one hand. Its great advantage is fast response and large-area probe with Geiger-Müller tube used as a detector. DC-3H-08 is the latest type coming out of type series DC-3 and was developed by the innovation of previous type DC-3E-98. This device was developed by the company VF a.s. Cerna Hora using financial sources coming from European Union for the Fire Rescue Service of the Czech Republic. It is the instrument with satisfactorily large display and robust construction suitable for measuring outdoors. It is consisting of two independent parts - indicator and basic units. When mounted together, the device works as complex, when separated, each unit can work independently and the communication between them is wireless using Bluetooth. The device is possible operate using four buttons at the indicator unit. It is possible to use the device for measuring kerma dose in the air, areal dose equivalent dosage, surface activity, accumulated dose and for checking people's contamination. The disadvantage of the device is its heavy weight and impossibility of controlling audio output, operating time (only 4 hours), and its high purchase price when compared to others. Ultra-Radiac (U-RAD115) is hand detector determined for indication of gama radiation sources, measuring dose rates, scheduling the time for people who intervene, setting-out safety zone for gama radiation and for direct data reading of accumulated dose. The device is company Canbera Dover Inc.' product. It is device of smaller size; its operation is actually easy and intuitive with the help of six buttons. It is suitable to be used outdoors because of its robustness. This device is recently sufficient for basic units HZS CR and when Canberra Packard finishes prototype stage of beta probe of this device for our market, it can fully replace device DC-3E that is recently serving out.
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