Author: ZOLTÁN SAS. Chemical and Environmental Sciences PhD School. Supervisor: JÁNOS SOMLAI PHD associate professor

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1 DETERMINATION OF INFLUENCING PARAMETERS OF RADON EMANATION AND EXHALATIONS Author: ZOLTÁN SAS Chemical and Environmental Sciences PhD School Supervisor: JÁNOS SOMLAI PHD associate professor University of Pannonia Institute of Radiochemistry and Radioecology 2012

2 ABSTRACT In theoretical part of this dissertation the author summarizes the possibilities of the natural radioactive sources, the regulations, the risk reduction and the radioanalitical methods of radiation dose originated from building materials. In experimental section he unfolds the radiation protection effects in Hungary resulting from the inbuilt of bulk amount used building materials. He examined 27 different type of clay starting material originated from 16 miscellaneous company seats. The radionuclide content of the collected samples was determined by the aid of gamma spectrometry. On the basis of the obtained results he classified the examined materials by reason of EU recommended classifying method (I-index). The author demonstrates the determination method of the radon emanation and exhalation modifying parameters on a selected clay sample and defines the optimal conditions of the measuring procedure. He displays the obtained results of the optimized radon exhalation and emanation measurements. He performs heat-treatment on selected clay between C temperature ranges and investigates the changes in case of radon emanation and exhalation as well. Furthermore the internal structure changes were surveyed detail, such as porosity, specific surface, superficial morphology, phase identification via XDR phase analysis and thermal stability. Significant correlation was found between the obtained exhalation profile and the internal structure parameters. As a result of the investigation he determines the main influential internal structure parameters. THESES Building material classification of Hungarian clay in radiological point of view o On the basis of the EU recommended building material classification method the calculated I- index (derived from the natural radionuclide content) of the examined 27 clay samples used in building material factories was lower than 1.0 limit. Due to that fact it can be safely stated, that the investigated clays are suitable for bulk amount used building material from gamma dosimetric point of view if the 1.0 msv/a limit will be passed. In case of the preamble of the stricter limit (0.3 msv/a) only 3 clays will be adapted for brick making. The developed method for determination of radon emanation and exhalation influential parameters and the obtained results o The obtained results derived from investigation of radon exhalation influencing effect of sample thickness clearly prove that the special type of free exhalation, so-called free exhalation is suitable for radon exhalation determination of porous materials. Since the phenomenon only depends on the radon potential and the amount of the investigated sample. o In the course of my measurements it was proved that the radon emanation of the investigated sample can be calculated from the obtained free exhalation value without the secular equilibrium state between the Ra-226 and the Rn-222. o Further advantage of the applied method that the Ra-226 determination of the sample is unnecessary to get the radon potential. The calculated equilibrium state radon concentration derived from free exhalation is sufficient.

3 o In the case of dry, pulverized clays the decrease of specific exhalation cannot be observed. The radon exhalation inhibition effect of moisture content becomes significant above 25 % moisture content. o As a result of my measurements it came to light that the emanation coefficient rises as a function of increasing moisture content. Approximately 5 % moisture content doubles the radon emanation, the radon potential and the free exhalation as well. Due to that fact the widely used measurements of dry state materials does not provide sufficially informing results. Relying upon the strength of these findings the determination of moisture content influencing effect in case of bulk amount used building materials is considerably reasonable. o Explicit, exponential correlation was found between the specific exhalation and the internal structure features, such as the average pore size, the effective porosity and the average specific surface as well. In the case of the heat treated clays the effective porosity less than 300 nm ranges has an effect on the emanation coefficient, the radon potential and the radon exhalation as well. In case of clays the applied heat treatment greatly decreases the radon exhalation capacity of the final product. Above 750 C the degree of radon exhalation can be reduced under two order of magnitude of the initial value. The obtained results clearly prove that the examination of the connection between the radon exhalation and the internal structure features changes during the manufacturing afford chance to reduce the radon exhalation of final products. On the basis of the obtained results the author recommends the reducing of the effective porosity for reductions of radon exhalation. Incompletions of regulation and examination method of building material inbuilt conditions o In the case of planned international and Hungarian regulations the radon levels of the dwellings will be limited via the Ra-226 activity concentration of the building materials. However my measurements expressly prove that the same material has significantly different radon exhalation features pending on its state, such as the thickness, the moisture content, the effective porosity and the specific surface of the inbuilt material. Owing to the low diffusion capability of non-porous materials the intended limit can be gratuitously strict. On the contrary the porous materials with high emanation coefficient and exempt from heat treatment, such as adobe the radon exhaling capability can be higher with 2-3 orders of magnitude if it is compared with the heat-treated bricks originated from the same starting material. Due to the listed facts it can be safely stated that the limitation of the Ra-226 activity concentration content of the building materials is not sufficient for prevention of incidentally evolved high radon levels in buildings.

4 PUBLICATIONS 1. Zoltán Sas, János Somlai, Viktor Jobbágy, Tibor Kovács, Gábor Szeiler: Radiological Aspects of Red Mud Disaster in Hungary, Third International Geo-Hazards Research Symposium, Tehri Garhwal, India, Z Sas, J Somlai, V Jobbagy, G Szeiler, T Kovacs: Radon emanation and exhalation characteristic of clays and modifying effect of heat treatment, International Symposium on Natural Radiation Exposures and Low Dose Radiation Epidemiological Studies, Hirosaki, Japán, (Hirosaki University) 3. Z Sas, J Somlai, G Szeiler, T Kovács: Radon emanation and exhalation characteristic of heattreated clay samples, RADIATION PROTECTION DOSIMETRY 152:(1-3) pp (2012), IF: Z Sas, J Somlai, J Jónás, G Szeiler, T Kovács: RADOLOGICAL SURVEY HUNGARIAN CLAYS AND RADON EMANATION AND EXHALATION INFLUENTIAL EFFECT OF SAMPLE AND INTERNAL STRUCTURE CONDITIONS, First East European Radon Symposium, Cluj-Napoca, Románia, Cluj-Napoca: Editura Risoprint, p. 85. (ISBN: ) 5. N Kavasi, T Vigh, J Somlai, T Kovacs, Z Sas, Cs Nemeth, T Ishikawa, H Yonehara: Natural Radioactivity of manganese clay: III. Terrestrial Radionuclides in Environment International Conference on Environmental Protection, Veszprém, HUNGARY, 16 18th May (2012) 6. T Kovács, Z Sas, J Somlai, V Jobbágy, G Szeiler: Radiological investigation of the effects of red mud disaster, RADIATION PROTECTION DOSIMETRY 152:(1-3) pp (2012), IF: János Somlai, Viktor Jobbágy, Zoltán Sas, Tibor Kovács, Gábor Szeiler: Radiological investigation of hungarian bauxites and red muds, III. Terrestrial Radioisotopes in Environment: International Conference on Environmental Protection, Veszprém, Magyarország, Veszprém: Pannon Egyetemi Kiadó, pp (ISBN: ) 8. J Somlai, G Szeiler, V Jobbagy, Z Sas, P Bui, T Kovacs: Red mud disaster in Hungary from Radiological point of view: Risk assessment and estimation of dose exposures, International Symposium on Natural Radiation Exposures and Low Dose Radiation Epidemiological Studies, Hirosaki, Japán, (Hirosaki University), Hirosaki: Hirosaki University, p Somlai János, Gál Nelli, Kopek Annamária, Szeiler Gábor, Sas Zoltán, Kovács Tibor, Kávási Norbert: The last 4 years' radon activity concentration tendency in Tapolca cave, VI. Magyar Radon Fórum: A Radon a Környezetben Nemzetközi Workshop, Veszprém, Magyarország, Veszprém: Pannon Egyetemi Kiadó, pp (ISBN: ) 10. Sas Zoltán, Somlai János, Jobbágy Viktor, Kovács Tibor, Szeiler Gábor: Radiological investigation of the effects of red mud disaster, VI. Magyar Radon Fórum: A Radon a Környezetben Nemzetközi Workshop, Veszprém, Magyarország, Veszprém: Pannon Egyetemi Kiadó, pp (ISBN: ) 11. Sas Zoltán, Somlai János, Jobbágy Viktor, Szeiler Gábor, Kovács Tibor: Radiological investigation of Hungarian clays (used in brick factories), VI. Magyar Radon Fórum: A Radon a Környezetben Nemzetközi Workshop, Veszprém, Veszprém: Pannon Egyetemi Kiadó, pp (ISBN: )

5 12. Kovács Tibor, Somlai János, Kovács József, Bui Pál, Sas Zoltán, Szeiler Gábor: Radiological concerns of the red mud field of the vicinity of Ajka (Hungary), VI. Magyar Radon Fórum: A Radon a Környezetben Nemzetközi Workshop, Veszprém, Pannon Egyetemi Kiadó, pp (ISBN: ) 13. Somlai J, Kovács J, Sas Z, Bui P, Szeiler G, Jobbágy V, Kovács T: Vörösiszap-tározó sérülésével kapcsolatos sugárterhelés becslése, MAGYAR KÉMIKUSOK LAPJA LXV:(12) pp (2010) 14. Somlai J, Kovács T, Kovács J, Sas Z, Szeiler G: Ajka környéki vörösiszap mező radiológiai vonatkozása, Őszi Radiokémiai Napok, Keszthely, Magyarország, Keszthely: MTA Radiokémiai Bizottság, p. 1. (ISBN: ) 15. Sas Z, Kávási N, Vigh T, Kovács T, Szeiler G, Somlai J, Szabó P: Mangánosagyag radionuklid koncentrációja, minősítése az építőipari felhasználhatóság szempontjából, III. Úrkút ANKÉT Konferencia, Ajka, február (2008) 16. Sas Z, Jobbágy V, Somlai J, Szeiler G, Oláh A, Szabó P, Kovács T: Az Almásfüzitői Timföldgyár vörösiszap tározóinak radiológiai vizsgálata, vörösiszap építőipari felhasználásának kockázata, XVII. Környezeti ártalmak és a légzőrendszer, Hévíz, Magyarország, Hévíz: Levegőszennyezés Által Veszélyeztetettekért Alapítvány, pp (ISBN: )

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