222Rn Activity Concentration Research Articles

Prototype of a primary calibration system for measurement of radon activity concentration

To calibrate measurement devices for monitoring the activity concentration of 222Rn in air, a prototype of a calibration facility is tested using a solid 226Ra source and a high-purity germanium (HPGe) detector. An emanation box was mounted on the detector for online gamma measurements. Inside this box, a 32.8kBq ±3% 226Ra standard source was placed. An AlphaGUARD control radon monitor was connected to the emanation box with a pumping air system in an open flow mode as a reference monitor. The emanation coefficient of the source was controlled online by comparing the gamma activity of 214Bi (Eγ=609.3keV), progeny of 226Ra, to that of the calibration source. A standard 137Cs source, installed within the emanation box, was used as a reference for gamma spectroscopy using the HPGe detector, with a total systematic error of 4% and a random error less than 2%. The ratio between gamma measurements and AlphaGUARD was 0.94±0.4; which is within the 9% uncertainties of AlphaGUARD calibration.

Hydrogeochemistry of thermal groundwaters in the Serbian crystalline core region

Geochemical exploration has been applied for studying thermal groundwater characteristics in the Serbian crystalline core region. Within this hydrogeological region, thermal groundwater with temperature higher than 20°C occurs at seven locations. The maximum discharge temperature of the thermal groundwater is 105°C which is the highest groundwater temperature encountered in Serbia. Geothermal reservoirs are present within andesite, schist, grus (the fragmental products of in-situ granular disintegration granite), marl and sandstone.Based on the concentrations of the major elements all of the water samples are of HCO3–Na to SO4–Na type. An elevated content of F, B, Ge and Rb is observed, while some samples also exhibit higher concentrations of As, Be, Cs, Ga, Ge, Li, V and W, and one has elevated concentrations of Nb, Zr and heavy rare earth elements (HREE). The groundwater is neutral to alkaline with TDS of 130–3822mg/L.Making use of various geothermometers, it was estimated that the temperatures in the selected aquifers of the Serbian crystalline core range from 45 to 146°C.Activity concentration of 222Rn ranges from 10.4±0.9 to 104±15Bq/L and is higher in groundwater that is in contact with schist and along faults, while 226Ra has a smaller activity concentrations, within the range of 0.21±0.09 to 0.48±0.18Bq/L.

Application of spectral decomposition of 222Rn activity concentration signal series measured in Niedźwiedzia Cave to identification of mechanisms responsible for different time-period variations

The authors present an application of spectral decomposition of 222Rn activity concentration signal series as a mathematical tool used for distinguishing processes determining temporal changes of radon concentration in cave air. The authors demonstrate that decomposition of monitored signal such as 222Rn activity concentration in cave air facilitates characterizing the processes affecting changes in the measured concentration of this gas. Thanks to this, one can better correlate and characterize the influence of various processes on radon behaviour in cave air. Distinguishing and characterising these processes enables the understanding of radon behaviour in cave environment and it may also enable and facilitate using radon as a precursor of geodynamic phenomena in the lithosphere. Thanks to the conducted analyses, the authors confirmed the unquestionable influence of convective air exchange between the cave and the atmosphere on seasonal and short-term (diurnal) changes in 222Rn activity concentration in cave air. Thanks to the applied methodology of signal analysis and decomposition, the authors also identified a third process affecting 222Rn activity concentration changes in cave air. This is a deterministic process causing changes in radon concentration, with a distribution different from the Gaussian one. The authors consider these changes to be the effect of turbulent air movements caused by the movement of visitors in caves. This movement is heterogeneous in terms of the number of visitors per group and the number of groups visiting a cave per day and per year. Such a process perfectly elucidates the observed character of the registered changes in 222Rn activity concentration in one of the decomposed components of the analysed signal. The obtained results encourage further research into precise relationships between the registered 222Rn activity concentration changes and factors causing them, as well as into using radon as a precursor of geodynamic phenomena in the lithosphere.

Indoor radon and gamma spectrometric measurements for the Erzincan Basin on North Anatolian Fault Zone, Turkey

Indoor radon and soil radioactivity levels were determined for Erzincan province in Turkey. Indoor radon concentrations were determined in 89 dwellings using CR-39 passive Solid State Nuclear Track Detectors (SSNTDs) for four seasons. The mean annual 222Rn activity concentration was found to be 119 Bq.m−3. In the winter season, indoor radon concentrations showed the highest values while the lowest values were observed in the summer season. A model was used to predict the number of lung cancer incidences due to inhalation of radon. The findings have indicated that radon is responsible for 13% of lung cancer incidences occurring in the Erzincan province. Since indoor radon concentration correlates with 226Ra content in soil beneath the dwellings, soil samples were collected near the houses where indoor radon measurements were performed in order to seek a correlation. The 226Ra, 232Th, 40K and 137Cs activity concentration values were 52, 26, 649 and 9 Bq.kg−1, respectively. The annual effective dose due to naturally occurring radionuclides was around 82 µSv.y−1 which is higher than the world average value of 70 µSv.y−1. The results of the present study are expected to be a useful baseline data for future studies.

222Rn Distribution Pattern in Dwellings of Copper Mineralized Area of East Singhbhum Region, Jharkhand, India

Seasonal variation of 222 Rn levels was studied in the dwellings in U-Cu mineralized area of East Singhbhum, Jharkhand, India. Copper mining and processing industry is operational in this area for the last hundred years. Copper minerals of this region contain a significant fraction of uranium and the decay products. To measure the activity concentration of 222 Rn, LR-115, type-II solid-state nuclear plastic track detector was used in an indigenously developed radon dosimeter cup. A higher value of 222 Rn activity concentration was recorded in some of the dwellings in the mineralized zone. The results at different locations adjoining the facilities show that the 222 Rn activity concentration varies to a great extent following an approximate log-normal distribution. The observed range varied from 29.1 and 314.6 Bq m -3 with an overall geometric mean of 72.3 Bq m -3 and geometric standard deviation 1.67. Further, in poorly ventilated dwellings 222 Rn levels were higher compared to the properly ventilated houses. The peak activity concentration of 222 Rn was recorded during winter (December-February). Appreciably lower activity concentration of radon was observed during summer and rainy seasons. The results reflect that the levels are higher than the global average indoor activity concentration of 40 Bq m -3 (UNSCEAR-1993) for 222 Rn, but are comparable to the studies carried out in similar types of geological formations.

The role of mesoscale meteorology in modulating the 222Rn concentrations in Huelva (Spain) – impact of phosphogypsum piles

The combined analysis of 222Rn activity concentrations and mesoscale meteorological conditions at Huelva city (Spain) was addressed in this study to understand the potential impact of phosphogypsum piles on the 222Rn activity concentrations registered at this area. Hourly mean data from April 2012 to February 2013 registered at two sampling sites (Huelva city and in the background station of El Arenosillo, located 27 km to the south-east) have been used in the study.The results of the present study showed a large difference in mean radon concentrations between the two stations during the sampling period, 6.3 ± 0.4 Bq m−3 at Huelva and 3.0 ± 0.2 Bq m−3 at El Arenosillo. The analysis has demonstrated that hourly 222Rn concentrations at Huelva city above 22 Bq m−3, with nocturnal peaks up to 50 Bq/m3, mainly coincided with the occurrence of a pure sea-land breeze cycle. Mesoscale circulations in this region are mainly characterized by two patterns of sea-land breeze, pure and non-pure, with the phosphosypsum piles directly upstream (south) of the city during the afternoon on pure sea-breeze days. The difference between mean 222Rn activity concentrations at Huelva city were 9.9 ± 1.5 Bq m−3 for the pure pattern and 3.3 ± 0.5 Bq m−3 for the non-pure pattern, while in the background station concentrations were 3.9 ± 0.4 Bq m−3 and 2.8 ± 0.4 Bq m−3 respectively.Considering these large differences, a detailed analysis of composites and case studies of representative sea-land breeze cycles of both types and their impact on 222Rn activity concentration was performed. The results suggested that the presence of the phosphogypsum piles was necessary in order to justify the high 222Rn activity concentrations observed at Huelva compared with the background station in the afternoons on pure sea breeze days (1.5–2.0 Bq m−3). On the other hand, large night time differences between the two sites on these days were likely to be associated with a combination of shallow density currents travelling down the Guadalquivir valley and, again, the presence of phosphogypsum piles.The results have demonstrated a significant impact of the phosphogypsum piles on 222Rn activity concentrations in Huelva city during the occurrence of pure sea breeze days.

Radon concentration in groundwater of east coast of West Bengal, India

This study was carried out to find out the distribution of radon (222Rn) activity concentration measured in the groundwater samples from the East coast of West Bengal, India. The 222Rn activity in 20 groundwater samples were measured using Durridge RAD-7and the values of 222Rn were found between 1.9 ± 0.78 and 9.0 ± 1.13 Bq L−1 with average of 5.0 ± 0.83 Bq L−1. These are well within the EPA’s maximum contaminant level of 11.1 Bq L−1.

Thoron and radon activity concentration in mineral waters of spas from southeastern Brazil

This work presents results of the measurements of thoron (220Rn) and radon (222Rn) activity concentration in 23 mineral waters sources occurring at the cities of Aguas da Prata, Pocos de Caldas, Aguas de Lindoia, and Aguas de Sao Pedro that are spas located at Minas Gerais and Sao Paulo States, Brazil. Physico-chemical parameters and dissolved gases have been also reported to understand the circulation environment of the waters, which indicated that it varies from transitional to reducing conditions. The thoron and radon activity concentrations ranged from 0.01 to 0.93 Bq/L and from 0.06 to 104 Bq/L, respectively. According to the Brazilian Code for Mineral Waters, these activities indicated that none of them are thoriferous, whereas two are weakly radioactive. The highest 220Rn and 222Rn levels were found in sources located in Pocos de Caldas and Aguas da Prata cities, within the Pocos de Caldas alkaline complex. This massif is a well-known suite of alkaline volcanic and plutonic rocks that possesses an accumulation of U, Th, other natural radionuclides, and rare-earth elements. In Villela spring, Aguas da Prata city, Sao Paulo State, the radon activity concentration exceeded the maximum allowed value of 100 Bq/L in drinking water as proposed by WHO in 2009. Although this spring is not utilized in a regular public water-supply system, there are taps available in a park allowing the water consumption by population. However, it has not been observed any health impact on local people that would need action taken by the Government.

Spatio-temporal Identification of Regions with Anomalous Values of 222Rn in Groundwater of Madurai District, Tamilnadu, India

Measurement of dissolved radon (222Rn) activity concentration in groundwater samples from private and public hand pumps, and in bore wells located at Madurai district of Tamilnadu, India, are presented. The study attempts to identify the background value of 222Rn in groundwater of hard rock terrain and the main aquifer contributing 222Rn, and to determine if any correlation exists with observed field parameters. Measured parameters included pH, TDS, Temperature and 222Rn in 42 samples for two seasons (South West Monsoon [SWM] and North East Monsoon [NEM]). The results show that the 222Rn activity concentration of the samples ranged from 0.049 to 59.952 Bq/L in South west monsoon and 0.12 to 211.60 Bq/L in North east monsoon. The higher activity was noted in NEM and the highest 222Rn concentrations were observed in granitic terrains in both seasons. The average values of the parameters studied shows that there is a general decrease of TDS and Temperature, but an increase in 222Rn and pH during NEM. The spatial representation of the activity shows that maximum values are in the north eastern part of the study area. Further, correlations between the measured parameters show that temperature has a negative correlation to the samples of charnockite formation during both seasons; pH and TDS also show negative relationships to 222Rn during SWM.

P.5.b.002 Mild cognitive disorder is a risk factor for dementia in middle-aged subjects with metabolic syndrome

In situ gamma spectroscopy is widely utilized to determine the outdoor gamma dose rate from the soil and to calculate the natural and artificial radionuclide concentration and their contribution to the dose rate. The application of in situ gamma spectroscopy in indoor environments can not supply quantitative information about activity concentration of radionuclides in building materials, but this technique can provide interesting information about building materials as radon source. In fact, a method based on analyses of gamma spectra data has been developed by the authors to provide, in field, quantitative estimation of disequilibrium in 226Ra and 228Ac sub-chains due to 222Rn and 220Rn exhalation. The method has been applied to data of gamma spectroscopy measurements carried out with HPGe detector (26%) in seven dwellings and one office in Rome. The first results of the data analysis show that, as regards especially the 226Ra sub-chain disequilibrium, different building materials (tuff, concrete, etc.) can show very different characteristics. If, in addition to the spectrometric data, other indoor environment parameters (indoor γ dose rates, room dimensions, wall thickness, etc.) (Bochicchio et al., Radiat Prot Dosim 1994;56(1–4):137–140; Bochicchio et al., Environ Int 1996a;22:S633–S639) are utilized in a room model, an evaluation of 226Ra, 228Ac and 40K activity concentration and an indication of the exhalation features, by means of estimation of exhaled 222Rn activity concentration, can be achieved.

Soil radon (222Rn) monitoring in a forest site in Fukushima, Japan

Soil radon (222Rn) has been monitored since August 2013 at three different soil depths on a campus forest of Fukushima University in Japan, where a large amount of fallout nuclides were released by the accident of Fukushima Daiichi Nuclear Power Plant in March 2011. The primary purpose of this study is to evaluate 222Rn activity level, variability and factors controlling 222Rn concentration in soil air using data obtained from August to December 2013. Time series of 222Rn activity concentration showed depth-dependent variability with an equilibrium value (222Rneq) during this observation period; 7.5, 14 and 23 kBq m−3 at 0.3, 0.6 and 1.0 m in depth, respectively. Two typhoons passing over the site had a great influence on soil radon level, which was practically used for evaluating effective diffusion coefficient of 222Rn. Transport mechanism of 222Rn in soil air was considered to be diffusion-controlled with data sets on changing 222Rn concentration with time in selected cases that showed decreasing (or increasing) 222Rn concentration with time at every depth. Important factors affecting soil 222Rn variability are meteorological parameters, low-pressure front passing over the site, and subsequent precipitation. Time lags of decreasing 222Rn concentration at different depths after rain indicate a certain relationship of 222Rn level with moving water (and water vapor) in soil. The findings obtained in this study are important to evaluate the fate of fallout nuclides (radiocesium) in contaminated forest sites using soil radon as a tracer of moving soil air.

Estimation of radon concentration in groundwater of coastal area in Baleshwar district of Odisha, India

The present study was carried out to determine the distribution of radon (222Rn) activity concentration measured using Durridge RAD-7 in the groundwater samples in the coastal area of Baleshwar district, Odisha, India. The 222Rn activities in 10 groundwater samples of coastal area of Baleshwar were measured and the values of 222Rn ranged between 1.6 ± 0.21 and 17.0 ± 1.69 kBq m−3 with an average value of 8.98 ± 0.85 kBq m−3, and seven samples were well within the Environmental Protection Agency's maximum contaminant level of 11.1 kBq m−3 while three samples were more than the maximum contaminant level of 11.1 kBq m−3. The effective dose per m3 and annual effective dose values were varying with respect to the increase in radon concentration and were significantly lower than the United Nations Scientific Committee on the Effects of Atomic Radiation and WHO recommended limit for members of the public of 1 mSv y−1.

222Rn and 226Ra activity concentrations in groundwaters of southern Poland: new data and selected genetic relations.

Since 2008, the authors have been conducting research into 222Rn and 226Ra activity concentrations in shallow circulation groundwaters in southern Poland. Measurements have been performed with a liquid-scintillation method and ultra low-level liquid-scintillation spectrometers α/β Quantulus 1220. The research carried out so far has demonstrated that in the Sudetes groundwaters with high activity concentrations of 222Rn and 226Ra are common. In other studied areas in southern Poland no shallow circulation groundwaters with high radon or radium concentrations have been found yet. The conducted research has demonstrated that the activity concentration of 222Rn dissolved in shallow circulation groundwaters in the Sudetes depends chiefly on the amount of radon, which after being released as gas from reservoir rocks is dissolved in waters flowing through these rocks. At the same time, the concentration of 222Rn dissolved in some shallow circulation groundwaters in the Carpathians is influenced significantly by the amount of radon produced from the decay of its parent ion 226Ra2+ dissolved in these waters.

Natural radioactivity around former uranium mine, Gabrovnica in Eastern Serbia

Gabrovnica near Kalna village was the first uranium mine established in Yugoslavia. In 1963, the Nuclear Energy Commission began operating the mine and mill. Between 1964 and 1966, the staff at Kalna extracted and produced an estimated 900 kg of UO2 and 400 kg of uranium metal. The Kalna ore was of poor quality, containing very low uranium content, which required higher-cost mining and refining methods. That was the main reason for closing this mine. This paper presents results obtained by measuring the activity concentration of soil samples measured by gamma spectrometry and also indoor 222Rn activity concentrations in houses in the nearby village Kalna. There is a presence of elevated radioactivity levels in the most of the measured samples. The mine was never officially decommissioned. The results obtained might be useful for the future decommissioning procedure.

Indoor radon concentration measurements at the site of the first nuclear power plant in Egypt

Radon (222 Rn) is a radioactive gas that occurs naturally when uranium in soil and rock breaks down. Long-term exposure to 222 Rn increases the risk of lung cancer. The principal objective of this work was to determine the 222 Rn activity concentration in an indoor air environment at the El-Dabaa site proposed for a nuclear power plant project in Egypt using the track etch technique with LR115 detectors. The annual average indoor 222 Rn activity concentration in apartment buildings varies from 24 to 77 Bq.m-3 , with a mean value of 54 Bq.m-3 . The annual effective dose received by residents of the studied area was estimated to be 0.41 mSv. The annual estimated effective dose is less than the recommended action level by ICRP (3−10 mSv.y-1 ). The results from this work provide a radiological assessment program and update the background of the natural radioactivity map at the El-Dabaa site.

Short-term radon activity concentration changes along the Underground Educational Tourist Route in the Old Uranium Mine in Kletno (Sudety Mts., SW Poland)

Short-term 222Rn activity concentration changes along the Underground Educational Tourist Route in the Old Uranium Mine in Kletno were studied, based on continuous measurements conducted between 16 May 2008 and 15 May 2010. The results were analysed in the context of numbers of visitors arriving at the facility in particular seasons and the time per day spent inside by staff and visitors. This choice was based on partially published earlier findings (Fijałkowska-Lichwa and Przylibski, 2011). Results for the year 2009 were analysed in depth, because it is the only period of observation covering a full calendar year. The year 2009 was also chosen for detailed analysis of short-term radon concentration changes, because in each period of this year (hour, month, season) fluctuations of noted values were the most visible. Attention has been paid to three crucial issues linked to the occurrence and behaviour of radon and to the radiological protection of workers and visitors at the tourist route in Kletno.The object of study is a complex of workings in a former uranium mine situated within a metamorphic rock complex in the most radon-prone area in Poland. The facility has been equipped with a mechanical ventilation system, which is turned on after the closing time and at the end of the working day for the visitor service staff, i.e. after 6 p.m.Short-term radon activity concentration changes along the Underground Educational Tourist Route in the Old Uranium Mine in Kletno are related to the activity of the facility's mechanical ventilation. Its inactivity in the daytime results in the fact that the highest values of 222Rn activity concentration are observed at the time when the facility is open to visitors, i.e. between 10 a.m. and 6 p.m.The improper usage of the mechanical ventilation system is responsible for the extremely unfavourable working conditions, which persist in the facility for practically all year. The absence of appropriate radiological protection (i.e. preventive measures like shortening working day, dosimetric measurements in the workplace) is a serious problem in the Kletno adit.

On the variability of atmospheric <sup>222</sup>Rn activity concentrations measured at Neumayer, coastal Antarctica

Abstract. We report on continuously measured 222Rn activity concentrations in near-surface air at Neumayer Station in the period 1995–2011. This 17-year record showed no long-term trend and has overall mean ± standard deviation of (0.019 ± 0.012) Bq m−3. A distinct and persistent seasonality could be distinguished with maximum values of (0.028 ± 0.013) Bq m−3 from January to March and minimum values of (0.015 ± 0.009) Bq m−3 from May to October. Elevated 222Rn activity concentrations were typically associated with air mass transport from the Antarctic Plateau. Our results do not support a relation between enhanced 222Rn activity concentrations at Neumayer and cyclonic activity or long-range transport from South America. The impact of oceanic 222Rn emissions could not be properly assessed but we tentatively identified regional sea ice extent (SIE) variability as a significant driver of the annual 222Rn cycle.

Radon in waterworks: dose assessment, analysis of influence parameters and improved methods of measurement

In Austria a comprehensive study on radiation exposure in waterworks was conducted. The aim of this study was to evaluate the risks for the affected employees. On the basis of geographical, geological and hydrological aspects, 21 waterworks were selected. A total of 85 passive short-term measurements and measurements with active devices for the detection of 222Rn were conducted and compared regarding their applicability to waterworks. Additionally, the results of 47 passive combined 222Rn/220Rn measurements for the detection of 220Rn are part of this paper. 222Rn was determined in row water samples. The influences of water flow rates and of the 222Rn activity concentration in water on the 222Rn activity concentration in indoor air of water supplies were investigated. On the basis of the results of radon measurements at 165 points, the annual effective doses for 74 persons of the staff were determined.

Temporal variability of radon in the atmosphere of Domica and Va ecka Karst caves (Slovakia)

Continual monitoring of radon activity concentration was performed in two caves: Domica and Važecká. Radon in the air of the Domica cave was monitored from June 2010 to July 2011. Radon research in the Važecká cave started in June 2012 and it is still being carried out. Radon concentration in cave atmosphere exhibited seasonal, short-term and daily variations. Daily average of radon in Domica varied from 0.5 to 2.7 kBq m(-3). Seasonal trend was characterised by the highest concentration in September and the lowest from February to March. Radon concentration in the Važecká cave was significantly higher, and the daily average ranged from 1.0 to 5.3 kBq m(-3). The highest values were registered from June to September and in January. The seasonal and daily variations of 222Rn activity concentration in the atmosphere of both caves are assumed to be associated with the atmospheric temperature. No effect of atmospheric pressure on radon short-term variation was found.

Characterization of 222Rn and meteorological parameters in Uro houses at South Kordofan state

This study was carried out to assess and map indoor radon concentration and to estimate radiation dose in Uro town in Sudan's South Kordofan state. A portable radon meter (RRA-01M-03), equipped with simple sensors of meteorological parameters has been used for carrying out radon measurement. The annual absorbed dose from the corresponding measured radon concentration was calculated using dose rate conversion factors of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The corresponding annual effective dose and equivalent dose to the lungs were estimated. Measured activity concentrations of 222Rn, annual absorbed dose, annual effective dose and equivalent dose to the lungs were found in the range 20–4482 Bq/m3, 0.32–70.67 mSv/y, 0.76–169.61 mSv−y and 0.16 × 10−7 to 35,856 × 3.5856 × 10−11 mSv−y, with geometric mean 109.43 Bq/m3, 1.73, 4.16 and 1.1 × 10−7 mSv−y, respectively. Upon comparing the results with global data, it was found with the exception of six samples, the obtained values fall far below the action level of 200–600 Bq/m3 recommended by the International Commission on Radiological Protection. However, the geometric mean is higher than the reported average global indoor radon concentration. Meteorological parameters were measured and no correlation was noted between radon concentration and these parameters. The overall annual effective dose was higher than the UNSCEAR recommended reference dose level of 1.0 mSv−y.