Thoron Exhalation Rate Research Articles

Investigation of radon and thoron exhalation rates in soils: Manali-Leh Highway region of Himalayas

This study analyses the natural radionuclides concentration (226Ra and 232Th) along with the radon and thoron exhalation rates in 50 soil samples collected from the Manali-Leh Highway region of the Himalayas. The specific activity of 226Ra and 232Th radionuclides was determined using a NaI(Tl) detector, revealing that the concentration values of these radionuclides are lower than the global average. The radon and thoron exhalation rates in the soil samples were measured utilizing a SMART RnDuo detector. The radon mass exhalation rates range from 6 to 87 mBq kg−1 h−1, with average values of 25 mBq kg−1 h−1. The thoron surface exhalation rates vary from 110 to 757 Bq m−2 h−1, with a mean value of 385 Bq m−2 h−1. Additionally, the emanation coefficient and alpha dose equivalent for radon were calculated and the correlation between parent and daughter radionuclides was also explored.

Radon exhalation rate from the latex pillows and its potential exposure to users

ObjectiveTo develop a new system to accurately measure the radon exhalation from the latex pillows, and to estimate its potential exposure to users. MethodsThe new system is composed of two loops, the first loop is designed to trap background radon and thoron until their levels are nearly zero, and the second loop is the measurement loop to detect radon and thoron exhalation rates from the pillows. ResultsThe results showed that mass radon exhalation rated ranged from 0.18 Bq·kg−1⋅h−1 to 0.78 Bq·kg−1⋅h−1, with an average of (0.36 ​± ​0.17) Bq·kg−1⋅h−1 in the 9 samples. The average annual effective dose to users in a model room was estimated to be (15.51 ​± ​12.69) μSv by assuming two pillows was used. These results demonstrate that the new system can effectively measure radon exhalation rates in latex pillows, and the potential exposure to radon exhalating from the pillows is very low.

Seasonal Variations in Radon and Thoron Exhalation Rates from Solid Concrete Interior Walls Observed Using In Situ Measurements

Building materials, such as brick and concrete, are known indoor radon (222Rn) and thoron (220Rn) sources. Most radon and thoron exhalation studies are based on the laboratory testing of pieces and blocks of such materials. To discuss if laboratory findings can be applied to a real-world environment, we conducted intensive in situ exhalation tests on two solid concrete interior walls of an apartment in Japan for over a year. Exhalation rates of radon (JRn) and thoron (JTn) were measured using an accumulation chamber and dedicated monitors, alongside monitoring indoor air temperature (T) and absolute humidity (AHin). There were weak correlations between JRn or JTn and T or AHin at one tested wall, and moderate correlations of JRn and strong correlations of JTn with T or AHin at the other wall, meaning more or less seasonal variations. The findings aligned with previous laboratory experiments on JRn but lacked corresponding data for JTn. Additionally, a moderate or strong correlation between JRn and JTn was observed for both tested walls. Comparison with theoretical calculations revealed a new issue regarding the impact of each process of emanation and migration within concrete pores on radon and thoron exhalation. Overall, this study provides insight into parameterizing radon and thoron source inputs in modeling the spatiotemporal dynamics of indoor radon and thoron.

An assessment of radionuclides level, radon and thoron exhalation rate in hill and field soil of Mahendergarh district in Haryana, India

An assessment of radionuclides level, radon and thoron exhalation rate in hill and field soil of Mahendergarh district in Haryana, India

Improved data analysis techniques for calculating more accurate radon and thoron exhalation rates from building interior solid walls

The impacts of mathematical models and associated parameters on radon (222Rn) and thoron (220Rn) exhalation rates based on in situ testing at building interior solid walls were demonstrated to improve data analysis techniques. The results showed that the heterogeneity of their activity concentrations within the measurement system was more significant for thoron than radon. The diurnal variation in indoor radon should be considered for better data quality. In conclusion, a model should be appropriately made and selected under the purposes and accuracy requirements of the exhalation test.

Radon and thoron exhalation rate from building materials: experimental evaluations and theoretical models

Radon and thoron exhalation rate from building materials: experimental evaluations and theoretical models

Measurement of the radon and thoron exhalation rates from the water surface of Yixin lake

The importance of determining the radon exhalation rate from water surface is emphasized by the increased use of radon and its daughter products as tracers in large-scale circulation studies of the atmosphere. There were many methods to measure radon exhalation from water surface. With the development of radon exhalation rate measurement methods and instruments on the surface of the soil, the rock and building materials, so the radon exhalation rate from water surface can be more accurately measured by applying these improved methods and instruments. In this paper, a cuboid accumulation chamber surrounded by foam boards and a RAD7 were used to measure the radon exhalation rate on the water surface at three different positions by Yixin lake. Each measurement was performed 2 h. The radon exhalation rate from the water surface was about 6 × 10−3 Bq m−2s−1. The thoron exhalation rate from the water surface also can be estimated, it is about 0.16 Bq m−2s−1. These results hint that the radon transmission from the lake bottom soil to water and then into the atmosphere.

Soil and air radon/thoron exhalation rates and radon activity concentrations in the vicinity of Lake Monoun, West region of Cameroon

ABSTRACTOne crucial element to determine the radon amount in the environment is the rate at which radon is exhaled from the subsurface. To assess the radon and thoron potential exhalation in the vicinity of Monoun Lake in the West Region of Cameroon, 28 soil samples were collected around the lake. Radon activity concentration in soil gas and air and the related risk to radon inhalation were evaluated. Radon and thoron exhalation rates, mass exhalation rates, and radon soil gas activity concentrations were derived from a mathematical model as a function of radium content and soil parameters. Radium activity concentrations were estimated using a gamma-ray spectrometry technique with a High Purity Germanium detector (HPGe). The average radon exhalation rate, thoron exhalation rate, radon mass exhalation rate, and thoron mass exhalation rate were found to be 22.7 mBq.m−2.s−1, 5348 mBq.m−2.s−1, 0.018 mBq.kg−1.s−1, and 321 mBq.kg−1.s−1, respectively. The registered radon and thoron exhalation rates were above the world average values of 16 Bq.m−2.s−1 and 1000 Bq.m−2.s−1 published by UNSCEAR, respectively. The calculated thoron exhalation in the study area was about 75.3 times higher than that of radon, which suggests probably more exposure to thoron gas than the radon in the area, despite its shorter half-life. A good positive correlation was found between radon and thoron exhalation rates. The obtained average values of radon activity concentrations in air and annual effective dose were above the world average values of 10 Bq.m−3 and 0.095 mSv published by UNSCEAR, but still below the threshold values of 148 Bq.m−3 and 1.4 mSv set as action levels by USEPA, respectively.

Radon and thoron exhalation rate in the soil of Western Haryana, India

This study reports the exhalation rates of radon and thoron from surface soil collected from 60 rural sites of district Hisar, Haryana, India. The exhalation rates of Rn222 (radon) and Rn220 (thoron) were measured by portable SMART RnDuo (AQTEK SYSTEMS) using a mass accumulation chamber which was equipped with a scintillation material-coated cell. Dose rates due to natural gamma radiations ranged from 0.526 to 1.139mSv y-1. The Rn222 mass exhalation rate in soil samples varied from 0.14 to 94.65mBqkg-1h-1. Thoron surface exhalation rates ranged from 46.42 to 619.88 Bqm-2h-1. This study gives an idea about the differences in Rn222 and Rn220 exhalation at different locations which may be due to variations in geological features of the locations and characteristics of the topsoil. The findings show that usage of study areasoil as building material is safe.

Radon and Thoron Exhalation Rate Measurements in Soil Samples Collected from the Vicinity of a Thermal Power Plant

Radon and Thoron Exhalation Rate Measurements in Soil Samples Collected from the Vicinity of a Thermal Power Plant

Estimation of radon in groundwater and analysis of radon and thoron exhalation rates of the soil in Mokokchung district, Nagaland, India

The present study of the analysis of radon in groundwater and its exhalation rates in soil was carried out in 19 selected locations in Mokokchung district, Nagaland, India. The survey was carried out by employing a portable scintillation-based smart RnDuo monitor. The radon (222Rn) mass exhalation rates of the soil were found to vary from 27 mBqKg−1h−1 to 40 mBqKg−1h−1 with an average of 31 ± 0.8 mBqKg−1h−1. While the thoron (220Rn) surface exhalation rate of the soil was found to vary from 714.6 Bqm−2h−1 to 2166.6 Bqm−2h−1 with an average of 1009.9 ± 77.1 Bqm−2h−1. The radon (222Rn) in drinking water was found to vary from 1.48 BqL−1 to 2.22 BqL−1 with an average of 1.82 ± 0.04 BqL−1 and is below the world average values as set by USEPA (1991), WHO (2004) and UNSCEAR (2008). Furthermore, the total effective dose range is below the WHO (2003) recommendation.

INFLUENCE OF SAMPLING FLOW RATE ON THORON EXHALATION RATE MEASUREMENTS BY THE CIRCULATION METHOD.

Researchers have used various methods to obtain the exhalation rates of radon and thoron from soil and building materials. One of the typical methods for radon exhalation rate is the circulation method using an accumulation container, an external or internal sampling pump and a continuous radon monitor. However, it is necessary to consider sampling flow rate if this method is applied to exhalation rate measurement for thoron due to its short half-life. Based on a calibration experiment, the measured thoron concentrations obtained by an electrostatic collection type radon and thoron monitor (RAD7) were found to be influenced strongly by the sampling flow rate. It was also found that the thoron exhalation rate from a soil sample depended on the pressure difference which was proportional to the increasing sampling flow rate. The thoron exhalation rate measured at the generally used sampling flow rate of the internal sampling pump of the RAD7 was overestimated compared with the value at 0 L min-1.

The Determination of Radon/Thoron Exhalation Rate in an Underground Coal Mine—Preliminary Results

The objective of this work was to perform a series of measurements of radon and thoron exhalation in the underground workings of an experimental coal mine. In the years 2012–2015, experiments on underground coal gasification were carried out in a coal mine, which caused, among other effects, damage to rock mass. Afterward, periodic increases in the concentration of potential alpha energy (PAEC) of radon decay products in the air were found, which could pose a hazard to miners. The question posed was whether the gasification experiment resulted in the increased migration of radon and thoron. If so, did it increase the radiation hazard to miners? The adaptation of the existing instrumentation to the specific conditions was conducted, and a series of measurements were made. It was found that the measured values of radon and thoron exhalation rates ranged from 3.0 up to 38 Bq·m−2·h−1 for radon and from 500 up to 2000 Bq·m−2·h−1 for thoron.

Effect of soil’s porosity and moisture content on radon and thoron exhalation rates

Effect of soil’s porosity and moisture content on radon and thoron exhalation rates

Effect of natural radionuclide's in the environment along the Jwalamukhi thrust of Himachal Pradesh, North West Himalayas, India.

This research paper is devoted to measure the activity contents of natural radionuclide, like, radium (226Ra), thorium (232Th) and potassium (40K) in the soil gathered along the Jwalamukhi thrust of Himachal Pradesh, North Western Himalayas, India. NaI(Tl) Scintillator detector was utilized for the estimation of activity content. The activity concentration of 226Ra, 232Th and 40K for some of the soil samples have been observed to be above the global normal mean values. The outcomes acquired for indoor and outdoor effective dosage are well below the normal international and national proposed results. The determined values of external hazard (Hex) for studied locations are less than unity, therefore; samples assembled from these regions are safe from a health hazard point of view and can be utilized as a construction purposes without producing any radio-logical hazard to human beings. The average estimations of radium equivalent activity were found to be within the limits suggested by Organization for Economic Cooperation and Development (OECD). Radon (222Rn) and thoron (220Rn) exhalation rates have also been calculated and discussed.

Study of environmental radioactivity and radon measurement associated health effect due to coal and fly ash samples

The increasing demand for electricity generation in India primarily depends on coal-fired power plants. The burning of coal is known as fly ash and a prominent factor of pollution in the environment. Fly ash generation in plants leads to the creation of radon and radionuclide, which affects the health of the general public. Since the general public around the area adjoining power plants are at considerable risk of radiation exposure. Also, inhalation of radon gas at a high level increases the possibility of lung cancer. So monitoring radon and radionuclide concentrations is essential. In the present investigation, radon and thoron exhalation rates have been estimated by implementing the accumulation method-based active technique. Natural radioactivity concentrations have been found out using NaI(Tl) detector-based gamma-ray spectrometry. Since the radiation hazard index is less than unity, so fly ash retains not a considerable amount of radiation effect. The result obtained concludes that radon/thoron exhalation rate and radioactivity concentration from fly ash residues are within the limits prescribed by the competent authority. So, the uses of fly ash in coal-based power plants cause no effectively adverse effect on health.

Radioactive Thoron 220Rn Exhalation From Unfired Mud Building Material Into Room Air of Earthen Dwellings

Thoron (220Rn), an isotope of radon with a strong α-decay energy, and its short-lived metallic progeny can pose an elevated lung cancer hazard in room air when unfired-soil derived building materials are used in earthen dwellings. Changes in moisture content and density influencing the thoron exhalation rate from earthen materials into room air were studied in the laboratory with terra rossa from a village on the Ðồng Văn Karst Plateau Geopark, Việt Nam, where ethnic minorities construct traditional dwellings with unfired terra rossa walls and floors. Our results show that the thoron exhalation rate from mud surfaces depends on (i) the content of radioactive parental nuclides in mineral components; (ii) the moisture content of mud where ∼5–10 weight % water maximizes the 220Rn exhalation rate; and (iii) the density of dry mud as primarily controlled by internal macroscopic voids, fractures, and porosity. Additional time-series of 220Rn exhalation data from an interior mud wall of a terra rossa-built house under different seasonal and weather conditions show that the temperature is influencing thoron exhalation via the water vapor pressure deficit (VPD) in air and the associated amount of atmospheric moisture adsorbed onto indoor mud surfaces. Our data suggest that occupants of “mud house” earthen dwellings in northern Việt Nam are exposed to an increased thoron geohazard during cooler weather, low VPD, and high relative humidity in air. Detailed studies are needed to evaluate the thoron geohazard for inhabitants of mud-built dwellings in other climates and geological terrains.

A Study of Natural Radioactivity Levels and Radon/Thoron Release Potential of Bedrock and Soil in Southeastern Ireland.

Radon (222Rn) and thoron (220Rn) account for almost two-thirds of the annual average radiation dose received by the Irish population. A detailed study of natural radioactivity levels and radon and thoron exhalation rates was carried out in a legislatively designated “high radon” area, as based on existing indoor radon measurements. Indoor radon concentrations, airborne radiometric data and stream sediment geochemistry were collated, and a set of soil samples were taken from the study area. The exhalation rates of radon (E222Rn) and thoron (E220Rn) for collected samples were determined in the laboratory. The resultant data were classified based on geological and soil type parameters. Geological boundaries were found to be robust classifiers for radon exhalation rates and radon-related variables, whilst soil type classification better differentiates thoron exhalation rates and correlated variables. Linear models were developed to predict the radon and thoron exhalation rates of the study area. Distribution maps of radon and thoron exhalation rates (range: E222Rn [0.15–1.84] and E220Rn [475–3029] Bq m−2 h−1) and annual effective dose (with a mean value of 0.84 mSv y−1) are presented. For some parts of the study area, the calculated annual effective dose exceeds the recommended level of 1 mSv y−1, illustrating a significant radiation risk. Airborne radiometric data were found to be a powerful and fast tool for the prediction of geogenic radon and thoron risk. This robust method can be used for other areas where airborne radiometric data are available.

Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations.

A long-term measurement technique of radon exhalation rate was previously developed using a passive type radon and thoron discriminative monitor and a ventilated type accumulation chamber. In the present study, this technique was applied to evaluate the thoron exhalation rate as well, and long-term measurements of radon and thoron exhalation rates were conducted for four years in Gifu Prefecture. The ventilated type accumulation chamber (0.8 × 0.8 × 1.0 m3) with an open bottom was embedded 15 cm into the ground. The vertical distributions of radon and thoron activity concentrations from the ground were obtained using passive type radon-thoron discriminative monitors (RADUETs). The RADUETs were placed at 1, 3, 10, 30, and 80 cm above the ground inside the accumulation chamber. The measurements were conducted from autumn 2014 to autumn 2018. These long-term results were found to be in good agreement with the values obtained by another methodology. The radon exhalation rates from the ground showed a clearly seasonal variation. Similar to findings of previous studies, radon exhalation rates from summer to autumn were relatively higher than those from winter to spring. In contrast, thoron exhalation rates were not found to show seasonal variation.

Intercomparison on the measurement of the thoron exhalation rate from building materials

Thoron (220Rn) exhalation from building materials has become increasingly recognized as a potential source for radiation exposure in dwellings. However, contrary to radon (222Rn), limited information on thoron exposure is available. As a result no harmonized test procedures for determining thoron exhalation from building materials are available at present. This study is a first interlaboratory comparison of different test methods to determine the thoron exhalation and a pre-step to a harmonized standard. The purpose of this study is to compare the experimental findings from a set of three building materials that are tested, and to identify future challenges in the development of a harmonized standard.