Evaluation of the radon concentration in Ocna Dej salt mine,Romania

Measurement of radon is of interest both for the health risk assessment and development of radon therapy in enclosed spaces like as caves, mines and spas. In Romania, radon therapy is not in use, yet. The development of this treatment method in mines from our country involves primarily, the evaluation of radon levels in the salt mines. In this paper, the results of radon gas measurement that were performed at Ocna Dej salt mine (Romania) are presented. The radon measurements were performed using two systems: radon monitor Pylon AB-5 system and CIS-P5M system. The average radon concentration was found to be between 9.14 ± 5.10 Bq/m³ and 31.70 ± 2.76 Bq/m³. These radon levels are lower in comparison to those reported for mines, caves or spas in other countries where radon therapy and speleotherapy is frequently in use. Radon concentration and environmental conditions from Ocna Dej salt mine are suitable for therapeutic applications.     

Soil gases (222Rn, 220Rn and total radon) and 214Bi measurements across El Avila fault near Caracas, Venezuela

Summary Radon measurements were performed across two sections of the Avila fault near Caracas, Venezuela. The radon concentrations clearly showed the different tectonic features and lithology at the Tacamahaca and Spanish Trail sites. ²¹⁴Bi (U-cps) measurements also were related to the lithology. The passive radon method employed laboratory-made dosimeters with LR 115, type 2 celulose nitrate films as detectors. They were buried in the ground at 30 cm depth. While, the active radon method was performed with a Pylon radon measurement system with Lucas cells. The soil gas was also sampled at 30 cm depths, but for only one minute, which was sufficient to fill the 150 cm³ Lucas cells completely. The total radon counts were then separated into those corresponding to ²²²Rn (radon) and ²²⁰Rn (thoron) by a simple computer routine. A comparison of the active and passive methods for the Tacamahaca section over a three-month period showed that both methods could locate precisely the active fault trace.     

Enhanced indoor radon concentration by using radon-rich well water in a Japanese wooden house in Fukuoka, Japan

Summary Radon measurements were carried out in a Japanese wooden house built on granitic geology, where radon-rich well water is used. Atmospheric radon concentrations were measured over one year with passive integrated radon monitors. The monitors were distributed at several locations in the house and were replaced every two months. In order to confirm the diurnal variation and heterogeneous distribution of radon, short-term measurements were carried out accordingly. Radon, its decay products and terrestrial gamma-radiations were measured in this survey. From the long-term measurement, the radon concentration in the house ranged from 14 to 184 Bq^. m^-3with an arithmetic mean of 45 Bq^. m^-3. A radon concentration of 184 Bq^. m^-3was observed in the bathroom in spring (March-May) though the radon level was normal in the living room and bedroom. In order to characterize the house, similar measurements were conducted in several surrounding houses. There was a significant difference in radon concentration between the investigated houses. There was a spatial distribution of the radon concentration and the highest value was found in the bathroom. Radon and its decay products concentrations varied with time, which increased from midnight to morning whereas they decreased during daytime. Although the radon concentration in tap water was 1 Bq^. l^-1, a high level of 353 Bq^. l^-1was found in the well water.While well water was being used, the indoor radon concentration near the bathroom increased rapidly with a maximum value of 964 Bq^. m^-3. It is clear that the use of well water enhanced the radon level around the bathroom.     

Indoor radon concentration levels in Mexican caves, using nuclear track methodology, and the relationship with living habits of the bats

This work presents the results of a study of the radon levels in four caves in Mexico: Los Riscos Cave and El Judío Cave in the State of Querétaro, and Coyozochico Cave and Karmidas Cave in the State of Puebla. The measurements were made using the passive closed-end cup system, with CR-39 (Lantrack^®) as detection material, and following protocols established for the measurement of indoor radon, developed at the Dosimetry Applications Project of the Physics Institute of the Universidad Nacional Autónoma de México. The radon concentration at one location with Karmidas Cave reached more than 60,000 Bq/m³, while concentrations in the other three caves varied from 83.1–1216.0 Bq/m³, was found. During the study was observed an interesting coincidence between the radon concentration distribution inside the caves, and the bat colonies location. In general, the bat colonies are located at the medium or low radon concentration levels zones.     

Short- and long-term monitoring of radon, thoron and carbon dioxide in soil-gas at Altos de pipe, Venezuela

We have measured radon and thoron activities in soil-gases since July 9, 1997 Cariaco earthquake (Mw=6.9) until the end of 2000. Carbon dioxide concentrations were also monitored between 1998–2000. The soil-gas was collected between 50–55 cm depths at two sampling points at Altos de pipe (Instituto Venezolano de Investigaciones Cientificas-IVIC) near Caracas, Venezuela. The radon and thoron measurements were performed daily employing radiation monitors with scintillation cells and the carbon dioxide was monitored with portable gas analyzers. Average weekly and monthly values were calculated and plotted for this three-four year period. In general, both the radon and carbon dioxide values showed sinusoidal trends due to seasonal changes. During the dry season the radon and carbon dioxide values decreased, while the radon activity was relative constant (flat) during the rainy season at one of the sampling points. Only two monthly radon values were seen to be anomalous in the graphs in respect to seven anomalous periods for the average weekly values. No anomalous periods were clearly seen for carbon dioxide. Finally, it was difficult to try to relate these radon anomalous periods with specific earthquakes due to the large number of minor earthquakes during these years, but it seem that the minor earthquake (Mb=5.9) of October 4, 2000 could be associated with the radon anomalous period in September, when there were no other minor earthquakes (Mb≥4.0). This revised version was published online in July 2006 with corrections to the Cover Date.     

Radon measurements in water samples from the thermal springs of Yalova basin, Turkey

The radon concentration has been measured in thermal waters used for medical therapy and drinking purposes in Yalova basin, Turkey. Radon activity measurements in water samples were performed using RAD 7 radon detector equipped with RAD H₂O (radon in water) accessory and following a protocol proposed by the manufacturer. The results show that the concentration of ²²²Rn in thermal waters ranges from 0.21 to 5.82 Bql^?1 with an average value of 2.4 Bql^?1. In addition to radon concentration, physicochemical parameters of water such as temperature (T), electrical conductivity, pH and redox potential (E_h) were also measured. The annual effective doses from radon in water due to its ingestion and inhalation were also estimated. The annual effective doses range from 0.2 to 0.75 μSvy^?1 for ingestion of radon in water and from 2.44 to 9 μSvy^?1 for inhalation of radon released from the water.     

Industrial commercial respirator filter as indoor radon monitor

This paper presents a method for measuring indoor radon concentrations using a commercially available air-purifying respirator filter as a component of the radon monitor. The filter used was Survivair’s NIOSH (National Institute for Occupational Health and Safety)-approved 100800 model. The method is based on the diffusion of radon gas into the activated carbon of the filter and the measurement of the radioactive daughters resulting from the radon decay. The photopeaks of the ²¹⁴Bi daughter gamma rays (0.609 MeV) were analyzed with a Hyper-Pure Germanium (HPGe) detector and a multichannel system. A monotonically increasing and very close to linear response relation between the integrated area under the ²¹⁴Bi photopeak and the radon concentration of the activated carbon was found. A well-defined relation held for radon levels ranging from 15 to 4,700 Bq/m³. This procedure results in highly reproducible and reliable measurements of indoor radon levels. Interesting applications include the investigation of radiological accidents involving radon and the retrospective measuring of indoor radon concentrations by analyzing the filters of the respirators worn by personnel working during the relevant period.     

Assessment of Summer Trends of Tropospheric Radon Isotopes in a Coastal Antarctic Station (Terra Nova Bay)

This work reports the first results of atmospheric radon measurements performed at the Italian Antarctic station located at Terra Nova Bay (74.69°S; 164.12°E) during summer campaigns of 1995-96, 1996-97 and 1997-98. Mean²²²Rn concentrations was 0.51 - 0.43 Bq m^m3 (median = 0.37 Bq m^m3), and ranged from 0.01 to 2.74 Bq m^m3 . On the average, these values were considered high, in comparison to results reported for other sites in Antarctica at equivalent latitudes. This could be explained by two causes: radon data for Terra Nova Bay were only for the summer period, when the ice-free area is at its maximum and thus the radon emission to the atmosphere; and by the larger ice-free area at Terra Nova Bay compared, for example, to measurements taken at another Antarctic site by the same technique (Ferraz station - 62°05'S; 058°23.5'W). The mean ²²²Rn to ²²⁰Rn activity ratio was 4.4 - 4.2, ranging between 0.1 and 45.3. The highest ratios indicated that some of observed surges of concentration of ²²²Rn could be attributed to not local sources. Lower radon concentrations were observed during katabatic wind events. The diurnal radon variation followed the general trend observed for continental areas located at lower latitudes.     

Indoor radon measurement in Izmir Province,Turkey

In 2013, an extensive study was performed in a total of 117 locations in Izmir province and indoor radon levels were measured using the alpha track etch integrated method with LR-115 detectors. As the maps are more practical to interpret the results of radiological survey, the distributions of indoor ²²²Rn activities in four most densely populated districts of Izmir were mapped in detail. It is seen that the estimated average radon concentration level (210 Bq m^?3) determined in Izmir province was almost three times higher than the mean value for Turkey (81 Bq m^?3). Exposed annual effective dose equivalents for Izmir province were estimated in the range of 0.7 to 12.3 mSv year^?1 with a mean of 5.3 mSv year^?1. In this study, it is pointed out that indoor radon concentration was affected by the age of the building and height above the ground.     

A simple laboratory-based radon calibration system

Measurements of ²²²Rn (“radon”) in the environment are important in the geosciences and radiation-protection fields. We demonstrate here a simple laboratory-based calibration system to evaluate the efficiency of radon detectors with a reproducibility of about ±2%. The system uses a closed-loop air circulation design with ²²⁶Ra adsorbed onto MnO₂-impregnated fiber as a radon source. Two RAD7 radon detectors (Durridge Co., Inc.) that were precisely calibrated at Durridge’s in-house calibration facility are used as secondary standards. By parallel analysis of the radon-enriched air within the closed loop, the test RAD7s are assigned a calibration coefficient to be applied to future measurements. We also performed a side-by-side intercomparison with two RAD7s in a high-radon natural environmental setting (limestone cave in Florida) that produced comparable results.     

Disturbing effect of CaCl2 used for drying in the measurement of 226Ra in water

A frequently used method in determining the radium concentration of water is the radon emanation method. When radon gas is transferred to the Lucas-cell usually CaCl₂ is used to remove the water traces. When we measured the background of the system using ultra clear distilled water the results were astonishing. The detailed investigation has shown that the unwanted radon originated from the CaCl₂, contained about 1000 Bq/kg of ²²⁶Ra. Depending on the time interval between two measurement, the radon deriving from the CaCl₂ disturbed the measurements.     

Detection efficiency improvement of a large volume scintillation cell

A large volume scintillation cell (LVSC) for radon activity concentration measurements has been reported at MARC-IV. The present paper describes improvements in the detection efficiency of the LVSC and results of the radon activity concentration measurements for indoor air that were performed using the improved LVSC. The cell is a cylindrical shape and has two photomultiplier tubes that are attached to a condensing lens on the photocathode so as to provide good light collection. Individual counting efficiencies were determined to be 0.48 for ²²²Rn, 0.55 for ²¹⁸Po, and 0.61 for ²¹⁴Po. The average counting efficiency per alpha-particle from the radon and its short half-life progenies was 0.55. This value is smaller than the original value reported by LUCAS of 0.86. However, the sensitivity is approximately eight times higher than that of the Lucas cell, which has a smaller volume. A background counting rate of 0.015 cps was obtained. The lower limit of detection (LLD) for the measurements was estimated using the average background counts, the detection efficiency and measurement time. The LLD at 80% statistics confidence limits was less than 10 Bq/m³ when counted within two hours.     

Radioactivity measurements as tool for physics dissemination

In general people associate environmental radioactivity with the artificial radioactivity and knows very little about natural radioactivity. Thus there is a critical need to improve nuclear physics public education. From 2005 in Italy two programs were promoted from Ministry of Education and University and National Institute of Nuclear Physics (INFN) for scientific dissemination in the field of environmental radioactivity. High school students in many Italian regions were involved in particular in indoor radon measurements. With this program students acquired awareness about the risks of inhalation of radon and its progeny and at the same time contributed to carry out radon monitoring, participating to all the experimental phases, from detectors set-up to data analysis. In particular we report about the activities carried out at Catania University and INFN division regarding a survey in the eastern Sicily. The overall monitoring, spanned over a period of 5 years, was carried out using passive nuclear track detection technique, through CR-39 dosimeters. In total about 500 detectors were placed in dwellings and schools in 57 locations. The investigated area have shown medium–high indoor radon concentrations, higher than the Italian average (70 Bq/m³). From the evaluation of the participating teachers and students, this kind of activities represents a successful strategy to enhance dissemination of physics, in particular in radioactivity topics.     

Investigations on the presence and distribution of radon in the Cacica salt mine,Romania

An important parameter for evaluating the possibilities of use of enclosed spaces (mines, caves, spas, etc.) for therapeutic purposes is the concentration of radon in different conditions of ventilation. The aim of this paper is to present the results of continuous radon gas measurement that were performed for ten days, at 20 min time intervals in different locations from Cacica salt mine (Romania) using a portable radon monitor. The average radon concentration was found to be between 96.5 ± 4.76 Bq/m³ and 20.5 ± 1.30 Bq/m³. These values are suitable for therapeutic applications and are useful for future experiments regarding the development of the radon therapy and speleotherapy in this salt mine.     

Investigation of radon and thoron concentrations in a landmark skyscraper in Tokyo

The temporal variation of the radon concentration, and the radon and thoron concentrations every 3 months for a year were measured using two types of devices in a landmark skyscraper, the Tokyo Metropolitan Government Daiichi Building. In the measurement of temporal variation of the radon concentration using a pulse type ionization chamber, the average radon concentration was 21 ± 13 Bq m^?3 (2–68 Bq m^?3). The measured indoor radon concentration had a strong relationship with the operation of the mechanical ventilation system and the activities of the office workers. The radon concentration also increased together with temperature. Other environmental parameters, such as air pressure and relative humidity, were not related to the radon concentration. In the long-term measurements using a passive radon and thoron discriminative monitor, no seasonal variation was observed. The annual average concentrations of radon and thoron were 16 ± 8 and 16 ± 7 Bq m^?3, respectively. There was also no relationship between the two concentrations. The annual average effective dose for office workers in this skyscraper was estimated to be 0.08 mSv y^?1 for 2000 working hours per year. When considering the indoor radon exposure received from their residential dwellings using the annual mean radon concentration indoors in Japan (15.5 Bq m^?3), the annual average effective dose was estimated to be 0.37 mSv y^?1. This value was 31 % of the worldwide average annual effective dose.     

Radon and thoron concentrations in offices and dwellings of the Gunma prefecture, Japan

Summary Aone year survey of indoor radon and thoron concentrations was carried out in offices and dwellings of the Gunma prefecture, Japan. A passive integrating radon and thoron discriminative monitor was used in the survey. The annual mean radon concentration was 22±14 Bq ^. m^-3, and ranged from 12 to 93 Bq ^. m^-3 among the 56 surveyed rooms. Radon concentration in offices was generally higher than that in the dwellings, with the arithmetic averages of 29 and 17 Bq ^. m^-3, respectively. Radon concentrations were generally lower in the traditional Japanese wooden houses than those houses built with other building materials. Seasonal variation of indoor radon was also observed in this survey. Compared to summer and autumn, radon concentrations were generally higher in spring and winter. The mean value of thoron to radon ratio was estimated to be 1.3, higher values were observed in the dwellings than in the offices. The annual effective dose from the exposure to indoor radon was estimated to be 0.47 mSv after taking the occupancy factors of offices and dwellings into account.     

Radon levels assessment in some Northern Romanian salt mines

Due to their low radioactivity background, underground salt mines spaces offer a unique possibility for speleotherapy use. The knowledge of radon concentration levels in such underground environments is essential for therapeutic purposes of different respiratory and rheumatic diseases. In order to develop speleotherapy in Romania, this paper presents the results of an indoor radon concentration levels survey in some salt mines in Romania. The survey was carried out using radon monitor Pylon AB-5 system methodology validated by a CIS-P5M system. In order to investigate whether differences in depth and microclimate parameters translate into significant differences in salt mine indoor radon concentrations, have been chosen three salts mine test sites placed in the Northern part of Romania (Turda, Cacica and Ocna Dej) in stable areas of the mining field at 32?C120?m depth. Environmental microclimate conditions (mean values of air temperature 10?C14.5?°C, air humidity 65?C80%, air velocity 0.2?m/s saline aerosols and low microbial factors) have anti-bacterial, anti-microbial, and anti-inflammatory properties and recognized therapeutically effects on human body??s health. Air temperature is one of the most important factors which need to be considered when carrying out a survey of indoor radon concentrations in salt mines because temperature largely determines close spaces ventilation rates, and ventilation habits are known to have significant effects on indoor radon concentrations. The analyzed environmental conditions and recorded low levels of indoor mean radon concentration (6.9?±?0.39 and 96.5?±?4.76?Bq/m³) demonstrated the best suitability of the investigated three salt mines in Romania for speleotherapeutic applications.     

Soil radon monitoring and anomalies in East Anatolian Fault System (Turkey)

On-line monitoring of soil radon (²²²Rn) concentration system was constructed on one of the main active fault zone of East Anatolian Fault System (EAFS) in Turkey. The preliminary results, observed during the second part of 2004 and first part of 2005 is presented. During the monitoring of soil radon concentration, numerous anomalies that equal or twice standard deviation were observed. In addition, the variation of the radon concentration was examined between the mean values and plus/minus two standard deviations and any increase in radon concentration above this limit was assumed to be ²²²Rn anomalies. These anomalies usually appeared between a few days or weeks before the earthquakes occurrence. The obtained data were also compared as considered respect to the earthquakes occurred in a 100 km radius of the fault system.     

Radioactivity measurement and standardization in Thailand

An absolute measurement method for disintegration rates of radioisotopes by 4p beta-gamma coincidence counting systems is described. Absolute activity of ⁶⁰Co and ⁹⁹Mo was determined by the counting systems of Japan and Thailand. Radon gas measurement and standardization were also performed. A radon chamber was constructed and employed for the comparative measurements by a pulse-counting ionization chamber and an environmental-level scintillation chamber. The background radon concentration of the radon chamber was also determined.     

Determination of the calibration factor for CR-39 based indoor radon detector

CR-39 based radon detectors are widely used in measuring indoor radon. In this regard, different groups have developed their own systems. However, before using any system for indoor radon measurements, it has, first, to be calibrated with a known source of radon. In the current study, CR-39 based NRPB type radon detector has been calibrated and presented. In this regard, about 200 holders for CR-39 were obtained from the Radiation Protection Division of the Health Protection Agency (former NRPB), UK and several thousand more similar detector holders, hereafter called NRPB type holders, were fabricated locally in Pakistan. Uranium ore samples of known grade were placed into the plastic containers of volume 5.4 × 10³ cm³ and CR-39 detectors were placed in the NRPB type holders and were then installed into the containers at a distance of 25 cm from the surface of the known grade ore samples. The containers were hermetically sealed and the detectors were allowed to expose to radon for 3 weeks. After 16 h etching in 25 % NaOH at 80 °C, the measured track densities were related to the radon concentration. The calibration factor of 2.563 tracks cm^?2 h^?1/kBq m^?3 was obtained.