Made available in DSpace on 2014-10-09T12:30:59Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:34Z (GMT). No. of bitstreams: 1 01405.pdf: 1516055 bytes, checksum: b8a1459d437208a6a35a67421f84f50e (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Caesium-137 is one of the major artificial radioactive elements, whose sources are atmospheric nuclear tests carried out in the 20th century and nuclear power plant incidents such as Chernobyl. Because of uneven precipitation, there were significant differences in radioactive fallout levels in different areas of the Czech Republic during the passage of the radioactive cloud from Chernobyl. Due to the high solubility of Caesium-137 in water and easy distribution in the environment, there is contamination of the lower soil levels where the plant root systems are located. The aim of this work is to collect soil samples from selected localities, where in 1986 significant contamination was detected as originating from Chernobyl, determination of their Caesium-137 content by gamma semiconductor spectrometry and comparison depending on the type of soil. The research question was set as: Does Caesium-137 content differ in different soil types? As part of this study, samples of uncultivated agricultural land and forest land were collected from layers 0-5, 5-10 and 10-15 cm in Kvilda, Zadov and Churanov. For comparison, results were also collected from a locality where the radioactive fallout was not so significant. This locality is around the village Straz nad Nezarkou, which is found on the protected nature reserves of Trebon. From the results of measuring the soil it was found that even after thirty years since the Chernobyl disaster occurred, Caesium-137 is still found in the upper layers of soils, specifically to depths of 5 cm. The highest specific activity of Caesium-137 was measured in the forest soils in Zadov at depths of 0-5 cm (364 Bq.kg-1) from the total range of all samples, 2,24 Bq.kg-1 to 364 Bq.kg-1. The highest specific activity of potassium K-40 was measured in uncultivated agricultural land in the locality of Kvilda at depths of 0-5 cm (883 Bq.kg-1).

The first part of thesis is engaged in explanation of some basic concepts regarding an elected topic: radioactivity, isotope, nuclide, halftime, gamaspectrometry etc. In the second part I deal with element cesium and influence of the Chernobyl accident. The final part processes questions of cesium - 137 in wood ecosystem. It is mainly concerned with research and gamaspectrometric measurement of wood substance, bark and samples of soil. In practical part (it is one part of the final part) I made taking of samples (especially soil from the depth 0-5 cm, soil from the depth 5 - 20 cm, wood substance and forest planting) from some localities above all the South Bohemian Region and next their gamaspectrometric measurement (quantitative analysis of cesium - 137 in wood ecosystem) at SÚJB in České Budějovice according to methodology.Measured values of cesium - 137 in samples were relatively low and its impact on the health of our population is in regard to other sources of ionizing radiance insignificant. The supposed hypothesis was herewith confirmed.

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Made available in DSpace on 2014-10-09T12:50:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:41Z (GMT). No. of bitstreams: 1 10886.pdf: 3145053 bytes, checksum: de92a5b14e97d88724cc81c6e671029b (MD5) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Made available in DSpace on 2014-10-09T12:51:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:55Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:54:28Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:55Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:32:34Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:11Z (GMT). No. of bitstreams: 1 03265.pdf: 2027580 bytes, checksum: bfb6b3f05e4a4d0ace77d6c9a4d3aa59 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

The State Office for Nuclear Safety (SONS) and the National Radiation Protection Institute (NRPI) are involved in independent monitoring of surrounding areas of nuclear power plants (NPPs), in accordance with the Czech legislative requirements (Decree No. 319/2002 Coll. on radiation monitoring network (RMS), as amended by Decree No. 27/2006 Coll.). The monitoring includes surveillance of environmental samples, in which radionuclides can be detected in case of emergency event, i.e. radioactivity release from the NPP. Another part of the monitoring is measurement of photon dose equivalent, continuously in the air (early detection network - SVZ) or using thermoluminescent dosimeters (TLD) placed in SONS monitoring points in the NPP vicinity. Environmental sampling and evaluation of photon dose equivalent in the air is carried out in regular intervals. The 137Cs and 131I activity is measured by gamaspectrometry method used with Gamat evaluation program, according to SONS internal procedure (VDMI). Tritium activity in surface water is measured by liquid scintillation spectrometer Beta TriCarb made by Canberra Packard Company, according to methodology CSN ISO 9698 (757635). Evaluation of dose equivalent rate is carried out continuously by LB 6360 proportional probe and LB 6500-3 Geiger-Muller tube located in RC Building in Ceske Budejovice. TLD evaluation is carried out by NRPI laboratory in Prague and the results are sent to SONS RC Ceske Budejovice. Goal of this work is to provide a set of results of the independent monitoring in surrounding areas of Temelin NPP (ETE) carried out between 1999 and 2009, by determination of volume, mass or surface activity of environmental samples (137Cs and 131I) and spot samples of water (3H) taken from SONS monitoring points near ETE . The set of such results should provide a baseline reference values for normal (pre-accident) situations. Additionally, based on the long term of the ETE surrounding surveillance, it can be shown that the ETE operation represents no threat to the health of the critical population group, and that the radiation situation in the ETE surrounding is stable. It can be also shown that the ETE operator meets requirements and conditions of authorized limits for discharging radionuclides into the environment. Procedures and method of independent environmental monitoring in the ETE surrounding during emergency events can be proposed on the basis of many years of experience with proven methodologies, experience with sampling locations, staffing and organization of measurement.