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Kavasi N.,Japan National Institute of Radiological Sciences | Vigh T.,Social Organization for Radioecological Cleanliness | Vigh T.,Manganese Mining Process Ltd. | Nemeth C.,Social Organization for Radioecological Cleanliness | And 5 more authors.
Review of Scientific Instruments | Year: 2014

During a one-year long measurement period, radon and thoron data obtained by two different passive radon-thoron discriminative monitors were compared at subsurface workplaces in Hungary, such as mines (bauxite and manganese ore) and caves (medical and touristic). These workplaces have special environmental conditions, such as, stable and high relative humidity (100%), relatively stable temperature (12 C-21 C), low or high wind speed (max. 2.4 m s-1) and low or elevated aerosol concentration (130-60 000 particles m-3). The measured radon and thoron concentrations fluctuated in a wide range among the different workplaces. The respective annual average radon concentrations and their standard deviations (in brackets) measured by the passive radon-thoron discriminative monitor with cellulose filter (CF) and the passive radon-thoron discriminative monitor with sponge filter (SF) were: 350(321) Bq m-3 and 550(497) Bq m-3 in the bauxite mine; 887(604) Bq m-3 and 1258(788) Bq m-3 in the manganese ore mine; 2510(2341) Bq m -3 and 3403(3075) Bq m-3 in the medical cave (Hospital Cave of Tapolca); and 6239(2057) Bq m-3 and 8512(1955) Bq m -3 in the touristic cave (Lake Cave of Tapolca). The respective average thoron concentrations and their standard deviation (in brackets) measured by CF and SF monitors were: 154(210) Bq m-3 and 161(148) Bq m-3 in the bauxite mine; 187(191) Bq m-3 and 117(147) Bq m-3 in the manganese-ore mine; 360(524) Bq m-3 and 371(789) Bq m-3 in the medical cave (Hospital Cave of Tapolca); and 1420(1184) Bq m-3 and 1462(3655) Bq m-3 in the touristic cave (Lake Cave of Tapolca). Under these circumstances, comparison of the radon data for the SF and CF monitors showed the former were consistently 51% higher in the bauxite mine, 38% higher in the manganese ore mine, and 34% higher in the caves. Consequently, correction is required on previously obtained radon data acquired by CF monitors at subsurface workplaces to gain comparable data for SF monitors. In the case of thoron, the data were unreliable and no significant tendency was seen during the comparison therefore comparison of previously obtained thoron data acquired by either CF or SF is doubtful. There was probable influence by relative humidity on the detection response; however, the effects of the high wind speed and elevated aerosol concentration could not be excluded. The results of this study call attention to the importance of calibration under extreme environmental conditions and the need for using reliable radon-thoron monitors for subsurface workplaces. © 2014 AIP Publishing LLC.

Kovacs T.,University of Pannonia | Sas Z.,University of Pannonia | Somlai J.,University of Pannonia | Jobbagy V.,Social Organization for Radioecological Cleanliness | Szeiler G.,University of Pannonia
Radiation Protection Dosimetry | Year: 2012

On 4 October 2010, the gate of a red mud waste dump of a Hungarian alumina factory was damaged and ~800.000 m3 of alkaline red mud flooded the vicinity of the dumps. Red mud samples were collected from the contaminated area and they were investigated from the radiological point of view. The activity concentrations were as follows: 232Th: 264 (194-337) Bq kg-1, 238U: 265 (197-332) Bq kg-1, 226Ra: 180 (143-237) Bq kg-1, 40K: 283 (228-360) Bq kg-1. As a function of the moisture content (0-28 %), the obtained radon emanation coefficients were relatively high (7.6-20 %) and, consequently, the radon exhalation also increased. © The Author 2012. Published by Oxford University Press. All rights reserved.

Csordas A.,University of Pannonia | Bator G.,Social Organization for Radioecological Cleanliness | Horvath D.,University of Pannonia | Somlai J.,University of Pannonia | Kovacs T.,University of Pannonia
Radiation Measurements | Year: 2016

Given that more than half of the radiation affecting humans is provided by radon and its progenies, surveying them has received a significant level of attention. Solid-state nuclear track detectors are most suited to carry out such surveys, e.g., CR-39-based detectors. Ordinarily, track detectors employ optical microscopes; however, in this study, a new scanner-based calibration and validation system is introduced. After exposure, the detectors were etched in a 6.25 M NaOH solution at 90 °C for 4.5 h; the diameters of the tracks developed in this way were typically 40-60 microns. Tracks were assessed using a Canon Canoscan 9000F scanner with a resolution of 4800 dpi, and Image Analyser software developed by ourselves. For the system calibration, known diameter tracks were prepared using an ArF excimer laser (λ = 193 nm), such that both the shape coefficient and the size of the tracks could be changed within the range of 10-100 μm. The operation of the scanner and the evaluation-shape recognition software were examined using repeatability and reproducibility tests. The system was capable of evaluating 100 detectors in an hour. The repeatability and reproducibility value of the system was excellent, with evaluation of the same detector on several occasions at different times producing a spread of 2%. The maximum spread for scanning in different positions was 3%. © 2016 Elsevier Ltd. All rights reserved.

Jobbagy V.,Social Organization for Radioecological Cleanliness | Kavasi N.,Social Organization for Radioecological Cleanliness | Somlai J.,University of Pannonia | Dombovari P.,Paks Nuclear Power Plant | And 2 more authors.
Radiation Measurements | Year: 2011

Hungary is rich in underground waters such as thermal, mineral, and spring waters. A survey was carried out to study the naturally occurring alpha emitter radionuclides in popular and regularly consumed spring waters in the Balaton Upland region of Hungary and significant levels of radioactivity were found. Thirty samples were analyzed for gross alpha and beta activity concentrations by the low background gas flow proportional counter. The activity concentrations ranging from 26 to 1749 mBq dm-3 and from 33 to 2015 mBq dm -3 for gross alpha and beta, respectively, were observed in the spring waters. In general, the gross beta activity was higher than the alpha activity concentration. According to the results obtained, elevated level of Total Indicative Dose (TID) might be expected due to spring water consumption. In some cases, total dose might exceed the 100 μSv y-1 reference level recommended by WHO. The data obtained can provide an important information for the consumers and the authorities regarding the preliminary dose exposure risk due to spring water intake. © 2010 Elsevier Ltd. All rights reserved.

Bezek M.,Jozef Stefan Institute | Gregoric A.,Jozef Stefan Institute | Kavasi N.,Social Organization for Radioecological Cleanliness | Kavasi N.,Japan National Institute of Radiological Sciences | Vaupotic J.,Jozef Stefan Institute
Radiation Protection Dosimetry | Year: 2012

At the lowest point along the tourist route in the Postojna Cave, the activity concentration of radon (222Rn) short-lived decay products and number concentration and size distribution of background aerosol particles in the size range of 10-1100 nm were measured. In the warm yearly season, aerosol concentration was low (52 cm-3) with 21 % particles smaller than 50 nm, while in the cold season, it was higher (1238 cm-3) with 8 % of <50 nmparticles. Radon activity concentrations were 4489 and 1108 Bq m-3, and fractions of unattached radon decay products were 0.62 and 0.13, respectively. © The Author 2012. Published by Oxford University Press. All rights reserved.

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