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In the new European Basic Safety Standard (EU-BSS), a new reference level for indoor radon concentration in workplaces has recommended that the annual average activity concentration of indoor radon shall not be higher than 300Bqm -3 . This paper describes the radon concentration level in an underground workplace (manganese ore mine) over long time intervals (4 years). Several common radon monitors devices - including NRPB and Raduet (as a passive method based on CR-39), AlphaGUARD PQ 2000Pro, SARAD EQF3220, TESLA and Pylon WLX (as active methods) - were used for continuous radon measurements. The output results were used, first, to comprised the result of each device, based on conditions present in underground mines; Second, to have comprehensive measurements about all factors that cause workers exposure to radiation (each monitoring device specified for a unique measurement). The results indicate that the mine's staff had successful efforts to reach the strict requirement of the new EU-BSS, and the average annual radon activity concentrations during the working hours were below 300Bqm -3 in the investigated period. The paper presents the effective dose calculations; applying different equilibrium factors suggested by the literature and calculated basing on our measurements at the site, concluding that the differences could be about threefold., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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.

Hungarian detectors modified and developed at the National Institute of Radiological Sciences (NIRS), Japan were placed at different sites, including homes and underground workplaces in Hungary, in order to gain information on the average radon (222Rn) and thoron (220Rn) concentration levels. Measurements were carried out in dwellings in a village and a manganese mine in Hungary. The radon and thoron concentrations in the dwellings of the village in the summer period were found to be 154 (17-1083) and 98 (1-714) Bq m(-3), respectively. Considering the results of other radon measurements during the winter (814 Bq m(-3)) and summer (182 Bq m(-3)) periods, the thoron concentrations were also expected to be higher in winter. In the manganese mine, radon and thoron were measured at 20 points for 6 months, changing the detectors each month. The averages were 924 (308-1639) and 221 (61-510) Bq m(-3) for radon and thoron, respectively. These results showed significant variance with the date and place of the measurement.

High concentrations of 226Ra (865-2,383 Bq kg(1)) were measured in the coal-slags, originated from the region of the settlement Tatabánya, Transdanubian Middle Mountains, Hungary. These slags are commonly used as building materials in this district. The external gamma dose rate was measured in 188 rooms at different heights above the floor. In 124 rooms with slags used for construction, the average absorbed dose rate was 296 nGy h(-1). In 10 apartments the average radon concentration was 502 Bq m(-3). In that case the estimated effective dose due to inhaled radon and its progeny and gamma radiation was 10.3 mSv y(-1).

Coals mined in the Transdanubian region in Hungary have an elevated concentration of 226Ra, which becomes enriched in the slag after burning. This slag has been used as filling andlor insulating material in building works. The aim of this study was to investigate the radiological situation in this territory in terms of the possible impact of this residual material from coal. Flats in three towns with a coal mine and a coal-fired power plant operating in their neighbourhood were examined. The radionuclide contents (including 226Ra, 232Th and 40K) of the slag used for building were determined, and the slags were categorised according to the international standards and recommendations. The external gamma dose rate and the radon concentration in the sites were measured, and based on these data dose assessments were made. The 226Ra concentration of the slag was 160-2893 Bq kg-1 the indoor gamma dose rates were 82-633 nGy h-1; the radon concentration measured with a nuclear track detector varied from 29 to 1310 Bq m-3 the assessed dose contributions in the three towns were 0.65-1.57 mSv y-1 due to gamma radiation and 2.2-15.2 mSv y-1 due to radon. [ABSTRACT FROM AUTHOR]

Abstract: In order to assess the dose due to radon in workplaces, it is important to know the concentrations during the periods when the workers are present though the data usually come from integrating measurements over the whole time. This paper describes discussions to show the possibility of inaccuracies in dose estimation. [Copyright &y& Elsevier]

Abstract: Radon and thoron and their progeny were measured using different methods in a dwelling in Gifu prefecture, Japan. The results indicate a considerably higher background level concerning radon and thoron compared to the average in Japan. [Copyright &y& Elsevier]