Intercomparison of Radon in Soil Instruments at Reference Site in Czech Republic

Intercomparison exercises of radon instruments play an important part when it comes to domestic survey as well as international or national mapping in dwellings, soil or water. Therefore, it is of prime interest to improve and standardize technical methods of measurement and also to verify quality assurance through comparison between different instruments and techniques. In the present paper is described the latest intercomparison exercise performed between the Laboratory of Environmental Radioactivity (hereafter called LER) of our department and other 15 different teams around Europe. The test has been held at two radon reference sites located 60 km SW of Prague, Czech Republic

Thoron/radon measurements in Romania and comparison with Macedonian schools

Radon problem has been widely investigated within the Romanian borders throughout the years while thoron did not attract that much of attention. However, fairly recent studies around the world have pointed out that indoor thoron should not be neglected when estimating the effective dose. Taking this into consideration a new survey is in progress, a survey that is going to provide the effective dose not only due to indoor radon but also the thoron contribution to it. Both dwellings and workplaces were selected for this investigation. The measuring method used is based on solid state nuclear track detectors with CR39 plats. A comparison exercise with Macedonian schools pointed out that both radon and thoron activity concentrations appears to be rather higher in Romanian schools with an average radon activity concentration of 89 Bq m-3 for the first versus 211 Bq m-3 for the last and respectively 19 Bq m-3 versus 80 for thoron. Notwithstanding, the Romanian dwellings presented slightly lower activity concentrations for radon, with an average of 193 Bq m-3 while thoron activity remained steady at 80 Bq m-3. However, the present paper analyzes only a low number of locations; a more substantial survey is yet in progress

Radon Concentration in Three Florida Caves: Florida, Jennings, and Ocala

This study reports the first radon concentration measurements within three frequently visited caves in Florida: one touristic (Florida Caverns), one private (Ocala Caverns), and one private, but publicly accessible (Jennings Cave). To measure the radon concentration, 18 CR-39 solid-state alpha track detectors were placed along the main passages of these caves for a period of 2 months (between December 2016 and February 2017). The results show that the radon concentration throughout all caves greatly exceeds the recommended safety action level. The highest concentrations of 2737 and 2958 Bq m−3 were recorded in Ocala and Jennings caves, respectively; whereas in Florida Caverns, the concentration reached a value as high as 1050 Bq m−3. To aid in ventilation, allowing the built-up gas to disperse, it is suggested that at Florida Caverns, the entry doors to be periodically opened for several hours. In locations with high concentrations where additional ventilation is not possible, such as Ocala and Jennings, it is recommended that the exposure time to be limited. Although radon values measured in the surveyed caves are high, the occasional cave visits are generally safe as the overall exposure time is minimal. However, cave guides and workers may have an increased risk as they spend many hours a day during which they are exposed to these high radon concentrations

Preliminary results from time integrated measurements concentrations of indoor radon, thoron and their progenies in schools of Republic of Macedonia

The results presented here are part of a survey on concentrations of radon, thoron and their progeny in different indoor environment of the Balkan region involving international collaboration. This paper presents the preliminary measurement results obtained in 43 schools of 5 municipalities in the Republic of Macedonia. The time-integrated radon and thoron gas concentrations were measured by CR-39 (placed in two chambers with different diffusion barrier), whereas the radon progeny and thoron progeny concentration (EECR and EECT) were measured by LR-115 nuclear track detectors based Direct Progeny Sensors (DTPS and DRPS). The detectors were deployed at least 0.5 m distance away from the walls as well as away from windows and doors, in order to minimize the thoron concentration variations, and exposed over three-month period (March–May 2012). The geometric mean values (and geometric standard deviations) of radon and thoron concentrations, EERC and EETC were: 76 Bq/m3 (1.7), 12 Bq/m3 (2.3), 27 Bq/m3 (1.4), 0.75 Bq/m3 (2.5), respectively. Equilibrium factors between radon and its progeny (FRn) and thoron and its progeny (FTn) were evaluated: FRn ranges from 0.10 to 0.84 and FTn ranges from 0.003 to 0.998 with geometric means (and geometric standard deviations) equal to 0.36 (1.71) and 0.07 (3.42), respectively. The linear regression analysis showed not significant correlation between the measured quantities. While the means appear plausible and well in line with values reported in literature, this is not so for some individual values. We discuss the technique and possible sources of errors and uncertainties

Results from Time Integrated Measurements of Indoor Radon, Thoron and their Decay Product Concentrations in Schools in the Republic of Macedonia

As part of a survey on concentrations of radon, thoron and their decay products in different indoor environments of the Balkan region involving international collaboration, measurements were performed in 43 schools from 5 municipalities of the Republic of Macedonia. The time-integrated radon and thoron gas concentrations (CRn and CTn) were measured by CR-39 (placed in chambers with different diffusion barriers), whereas the equilibrium equivalent radon and thoron concentrations (EERC and EETC) were measured using direct radon–thoron progeny sensors consisting of LR-115 nuclear track detectors. The detectors were deployed at a distance of at least 0.5 m from the walls as well as far away from the windows and doors in order to obtain more representative samples of air from the breathing zone; detectors were exposed over a 3-month period (March–May 2012). The geometric mean (GM) values [and geometric standard deviations (GSDs)] of CRn, CTn, EERC and EETC were 76 (1.7), 12 (2.3), 27 (1.4) and 0.75 Bq m−3 (2.5), respectively. The equilibrium factors between radon and its decay products (FRn) and thoron and its decay products (FTn>0.5 m) were evaluated: FRn ranged between 0.10 and 0.84 and FTn>0.5 m ranged between 0.003 and 0.998 with GMs (and GSDs) equal to 0.36 (1.7) and 0.07 (3.4), respectively

Radon Measurements and Radon Remediationin Băiţa-Ştei Pronearea

Băiţa-Ştei was the largest uranium reserve in Romania with estimated reserves of 450,000 tons of high grade metal. It was a large open pit mine in the northwest of Romania (West Carpathian Mountains), situated at 123 km south-east of Oradea, the capital of Bihor County. The transport during the time of sediment by Crişul Băiţa water course increased the uranium and radium content in the river meadow. The building material from Crişul Băiţariver bed (stone, gravel, sand) was used as construction material for the houses. In addition, some people living on this valley and surroundings after the opening exploitation used as building material the uranium waste from this mine. Preliminary indoor radon measurement (grab samples) in the villages situated on the route of ore transport (BăiţaPlai -Ştei) shown high radon concentrations, until 5000 Bq m−3. The new result obtained in this work in springer season 252 Bq m−3 is comparable with the annual means of 241 Bq m−3 and 229 Bq m−3 respectively, previously obtained, but more than twice times higher than the average value of 126 Bq m−3, computed for Romania. About 3000 of etched CR-39 track detectors were used followed by a selection of 20 houses proposed for remediation where a systematic investigation regarding radon sources was performed. The measured indoor radon concentration in the surveyed buildings ranged from 40 to 4000 Bq m−3. For experimental research, a representative pilot house was chosen. This house represents an example of a typical building from this area, with complex and various radon entry pathways which are correlated with the geology of soil. This building was chosen as pilot house due to the fact that it requires different ventilation systems or other remedial measures to be installe

Radon Levels in Romanian Caves: An Occupational Exposure Survey

A comprehensive radon survey has been carried out in seven caves located in the western half of Romania’s most significant karst regions. Touristic and non-touristic caves were investigated with the aim to provide a reliable distribution of their radon levels and evaluate the occupational exposure and associated effective doses. Radon gas concentrations were measured with long-term diffusion-type detectors during two consecutive seasons (warm and cold). All investigated caves exceed the European Union reference level of radon gas at workplaces (300 Bq/m3). The radon concentration in these caves ranges between 53 and 2866 Bq/m3, reflecting particular cave topography, season-related cave ventilation, and complex tectonic and geological settings surrounding each location. Relatively homogeneous high radon levels occur in all investigated touristic caves and in Tăuşoare and Vântului along their main galleries. Except for Muierii, in all the other caves radon levels are higher during the warm season, compared to the cold one. This suggests that natural cave ventilation largely controls the underground accumulation of radon. The results reported here reveal that the occupational exposure in Urşilor, Vadu Crişului, Tăuşoare, Vântului, and Muierii caves needs to be carefully monitored. The effective doses to workers vary between an average of 0.25 and 4.39 mSv/year depending on the measuring season. The highest values were recorded in show caves, ranging from 1.15 to 6.15 mSv/year, well above the European recommended limit, thus posing a potential health hazard upon cave guides, cavers, and scientists