Radon Exhalation Rate Research Articles

Temperature-humidity evolution and radon exhalation mechanism of red clay-bentonite covering layer in uranium mill tailings pond

To ensure the safety and stability of the beach surface of the decommissioned uranium mill tailings pond, this paper uses red clay-bentonite and red clay (1:1) to carry out covering layer radon reduction simulation experiments to study the temperature, humidity, and radon reduction effect of the covering layer under natural conditions. The results show that the radon exhalation rate of red clay-bentonite cover layer is only 0.32 times that of red clay, which has a better radon reduction effect. The red clay-bentonite cover layer has better water retention and comparable heat preservation effect than red clay cover layer. The red clay-bentonite and red clay temperature curves follow the same evolution trend and were close together in the same outdoor conditions, and the humidity curves showed a difference of 1% to 3%. Soil temperature is the dominant factor affecting the variation of radon exhalation of red clay-bentonite and red clay covering layer with unsaturated water content.

Numerical simulations of radon exhalation from surrounding rocks of single and double underground roadways

The radon exhalation rate of surrounding rocks in underground roadways is an important parameter in determining radon exhalation capacity and ventilation flowrate for radon removal. By approximating the roadways as thick-walled, porous cylinders, this study investigates radon exhalation from their surrounding rocks via simulations using computational fluid dynamics (CFD). Radon exhalation rates of single and double underground roadways were computed and analysed under different pressure differences, radon diffusion coefficients, permeabilities of rocks, single roadway locations and additional parallel roadway orientation. The radon regulating zone was presented and the effect of pressure difference on it was analysed. By fitting the data from simulation results, an estimation model was obtained for the radon exhalation rate of a single roadway. For two adjacent parallel roadways with a distance greater than or equal to 50m, the model is also suitable for estimating the radon exhalation rate when the rock permeability is less than 1 × 10−14 m2 and the ratio of permeability to diffusion coefficient is less than 5 × 10−9.

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

Assessing Radon (222Rn) Exhalation Rates from Building Tiles in Duhok, Iraq

Assessing Radon (222Rn) Exhalation Rates from Building Tiles in Duhok, Iraq

Radon gas concentrations and exhalation rates in soil samples of Al-Muthanna governorate, Iraq

Radon gas concentrations and exhalation rates in soil samples of Al-Muthanna governorate, Iraq

Numerical simulations for radon migration and exhalation behavior during measuring radon exhalation rate with closed-loop method

Numerical simulations for radon migration and exhalation behavior during measuring radon exhalation rate with closed-loop method

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.

Radon exhalation behavior and determination of diffusion migration parameters in spherical porous emanation media

There is a significant impact of the radon diffusion coefficient and the free radon production rate on the exhalation of radon from porous materials that can be regarded as spheres, hexahedrons, or cylinders. To understand this effect, the radon exhalation rules of spherical porous media with different radii were studied according to the radon diffusion migration theory. A specialized method for simultaneous determination of the radon diffusion coefficient and the free radon production rate of the spherical porous media was proposed, and applied to determine the above two parameters for two hemispherical test blocks with different radii. The results show that:(1) For spherical porous media with a certain radon diffusion length (Ld), as the radius (r0) of the sphere increases, the radon exhalation rate first increases, and tends to stabilize at r0≥6Ld; The free radon release share gradually decreases from approximately 1, and drops to a steady state at r0≥18Ld. (2) Compared with conventional methods, the relative error of the free radon production rate determined by the proposed method is within 3.9%, which verifies the reliability of the new method.

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.

Environmental Radioactivity of Alpha in Paint samples of Iraqi Markets

By using a sealed technology, radon levels were determined, annual effective dose, the effective content of radium, radon exhalation rate and uranium concentrations to be the total 30 samples materials used to paint the walls of buildings and homes in Iraq. It was found that the recommended value for all samples for radon concentration is with low potency radium content of 300 Bq / m3 and 370 Bq / kg respectively. In addition, Annual effective dose in all values was found to be less than the permission level (10 mSv / y). The values of exhalation rate relative to samples lower than the permission value (57.600 mBq/m2.h) set by UNSCEAR organization. The strong correlation (R2=1). It turns out that the content effective radium with the surface radon exhalation rate, the mass radon exhalation rate, and the uranium concentration, respectively. In general, the studied of 30 samples materials used to paint the walls of buildings and homes in Iraq be safe to use as construction material.

Influence of temperature on the radon concentration distribution in ramp under low-speed wind field: A numerical simulation study

By introducing the parameters of radon exhalation rate and radon diffusion coefficient, the distribution of radon concentration field on ramp under the condition of superposition of temperature field and flow field is simulated. The simulation results show that the distribution of radon concentration in the ramp under the condition of low-speed ventilation is greatly affected by the temperature field and flow field, and the change of radon exhalation caused by temperature is the main factor leading to the change of radon concentration in the ramp. The change of temperature will cause the overall increase of radon concentration in the ramp. Under the condition of constant flow field, the radon concentration in the chamber is more than two times higher than the average radon concentration in the ramp. Some areas severely exceeded the limit.

Determination of radon exhalation rates from sand of some beaches in Lagos, Nigeria and Benin

Determination of radon exhalation rates from sand of some beaches in Lagos, Nigeria and Benin

Study of the effect of temperature and water content on radon exhalation from phosphate using LR-115 detectors.

A study of the influence of moisture content on the radon exhalation rate from phosphate samples (with and without consideration of the back diffusion effect) was performed using the sealed cup technique. The mass exhalation rate was found to increase with an increase in moisture content, reaching a maximum value of 2.414±0.034Bqkg-1h-1 with a moisture content of 10%. However, the mass exhalation rate decreased with a continued increase in moisture content above 25%. The mass exhalation rate was also measured at different temperatures between -10 and 50°C. The obtained results show that the mass exhalation rate increases linearly with temperature. We point out that all the obtained values of radon exhalation rate are lower than the world average radon exhalation rate (57.6Bqm-2h-1).

Evaluation of Radon (222Rn) Exhalation Rates from Imported Granite Tiles Used as a Building Materials in Erbil Governorate, Kurdistan Region -Iraq

Evaluation of Radon (222Rn) Exhalation Rates from Imported Granite Tiles Used as a Building Materials in Erbil Governorate, Kurdistan Region -Iraq

A study of 226Ra concentration and radon exhalation rates in different geopolymer cement samples using CR-39 solid state nuclear track detector

Radon is a naturally occurring radioactive gas that is known to cause lung cancer. Therefore, it is essential to measure and determine the concentration of radon in different materials. The purpose of this research is to measure and analyze the levels of radon concentration, radium concentration, and radon exhalation rates in various geopolymer cement mixes. These mixes are made from slag or metakaolin blended with different ratios of fly ash, silica fume, and cement kiln dust. The main goal is to determine the potential risks associated with using geopolymer cement materials in construction and how they may impact indoor air quality. To achieve this, the study will monitor the amounts of radon released from different geopolymer cement mixes and compare them to traditional cement samples. A CR-39 solid-state nuclear track detector will be used for monitoring purposes. Results of this study have revealed that the radon concentration varies from 4.03 to 348.21 Bqm−3 with an average value 62.01 Bqm−3. Radium concentration also changes from 15.18 to 926.47 Bqkg−1 with an average value 174.23 Bqkg−1. The value of the dissolved radon concentration in the collected samples alters from 4.57 to 394.87 Bqm−3 with an average value 70.32 Bqm−3. The mass exhalation rates are found to vary from 0.04 to 2.28 Bqkg−1h−1 with an average value 0.43 Bqkg−1h−1, while the surface exhalation rates vary from 0.91 to 78.92 Bqm−2h−1 with an average value 14.06 Bqm−2h−1. The Annual Effective Dose (AED), due to conducting the experiment indoors, has varied from 0.102 to 8.785 mSvy−1 with an average value 1.564 mSvy−1, where AED in the outdoor experiment has varied from 0.038 to 3.294 mSvy−1 with an average value 0.587 mSvy−1. According to the results, the geopolymer mixes labeled as (S) and (SS) containing 100% GGBFS and 85% GGBFS with 15% SF respectively has had the highest levels of radium concentration, radon concentration, dissolved radon concentration, radon exhalation rates, and AED. The investigation results indicate that, with the exception of samples (S) and (SS), the analyzed samples fall within the suggested range of acceptable values. Based on our results, it seems that all geopolymer samples except for (S) and (SS) are safe for being used in building materials production. We recommend utilizing these samples (S, SS) for public highways, bridges, and other buildings that have good ventilation.

Measurement of radon concentration in soil gas and radon exhalation rate from soil samples along and across the Main Central Thrust of Garhwal Himalaya, India.

The present study focuses on measuring radon concentrations in soil gas at various depths, radon exhalation rate (surface and mass) from soil samples, and gamma dose rate along and across the Main Central Thrust of Garhwal Himalaya, India. Radon concentration in soil gas, surface, and mass exhalation rates was measured using a portable SMART radon monitor (RnDuo). Furthermore, the gamma dose rate was measured using a pocket radiation monitor. The soil gas radon concentration varied from 15 ± 4 to 579 ± 82Bqm-3 at a depth of 25cm, 10 ± 2 to 533 ± 75Bqm-3 at a depth of 30cm, and 9 ± 1 to 680 ± 95Bqm-3 at a depth of 35cm. The surface and mass exhalation rates were found 3 ± 0.7 to 98 ± 3Bqm-2h-1 (with AM ± SD = 36 ± 28Bqm-2h-1) and 1 ± 0.2 to 95 ± 2mBqkg-1h-1 (with AM ± SD = 30 ± 22mBqkg-1h-1), respectively. The gamma dose rate for the present study area varies from 0.11 ± 0.05 to 0.28 ± 0.05µSvh-1 with a mean value of 0.17 ± 0.05µSvh-1. The correlation analysis between the exhalation rates (mass and surface) and radon concentration of soil gas at various depths was carried out in the current study.

Assessment of environmental radiological hazards associated with elevated levels of radon gas in drinking water

The purpose of this study was to assess the environmental radiological hazards associated with elevated levels of radon gas in drinking water. Using passive (CR-39 plastic detector) and active (RAD 7) detectors, the radon levels in the air and drinking water (tap water) of 124 homes in 31 distinct locations in Iraqi Kurdistan were determined. Almost anywhere with a high indoor radon level also has a high radon exhalation rate from drinking water. The cities of Similan and Kelak had the highest and lowest radon concentrations using both techniques. A good correlation was found between the values of the average indoor radon concentration for active and passive detection methods. The values are smaller than the internationally recommended limit of 11 Bq/l as proposed by the Environmental Potential Agency (US EPA).

A comprehensive review of radioactive pollution treatment of uranium mill tailings.

Natural uranium is a crucial resource for clean nuclear energy, which has brought significant economic and social benefits to humanity. However, the development and utilization of uranium resources have also resulted in the accumulation of vast amounts of uranium mill tailings (UMTs), which pose a potential threat to human health and the ecological environment. This paper reviews the research progress on UMTs treatment technologies, including cover disposal, solidification disposal, backfilling disposal, and bioremediation methods. It is found that cover disposal is a versatile method for the long-term management of UMTs, the engineering performance and durability of the cover system can be improved by choosing suitable stabilizers for the cover layer. Solidification disposal can convert UMTs into solid waste for permanent disposal, but it produces a large amount of waste and requires high operating costs; it is necessary to explore the effectiveness and efficiency of solidification disposal for UMTs, while minimizing the bad environmental impact. Backfilling disposal realizes the resource utilization of solid waste, but the high radon exhalation rate caused by the UMTs backfilling also needs to be considered. Bioremediation methods have low investment costs and are less likely to cause secondary pollution, but the remediation efficiency is low, it can be combined with other treatment technologies to remedy the defects of a single remediation method. The article concludes with key issues and corresponding suggestions for the current UMTs treatment methods, which can provide theoretical guidance and reference for further development and application of radioactive pollution treatment of UMTs.

Investigation of Gebze-Darıca metro line (Kocaeli Province/Turkey) in terms of radon and gamma radiation levels

In this study, 222Rn and gamma radiation levels were measured in soil and rock samples taken from Gebze - Darıca Metro Line, which is under construction, within the borders of Kocaeli province (Turkey), which is an important industrial city. Measurements were made in the summer of 2021 and are interpreted by environmental factors such as depth, humidity, temperature, air pressure and geological formations (granite and non-granite) that may affect radiation levels. It was observed that radon concentrations were in the range of 145–3696 Bqm−3 in measurements made on soil samples. The highest radon values in rocks were measured in granodiorite (3242.8 Bq m−3) and granite (2253.4 Bqm−3) samples. The amount of radionuclide and radon in soils is higher than in rocks. In the measurements made at 48 selected points, the World Health Organization (WHO) limit value was exceeded at 27 points in total (%56 of all samples). There are six measurement points exceeding the limit values for both public and employees, with the highest annual average effective dose (H) for radon concentration of 2.94–23.55 mSv y−1 at S11. The highest surface radon exhalation rate was calculated as 508.02 Bq m−2 h−1 at station S11. Indoor measurements at 20 cm below the soil surface range from 81 to 252 nSvh−1, and all but S5 exceed the indoor gamma dose rate level of 84 nGy h−1 worldwide. Effective dose level caused by the gamma radiation originating from the Earth's surface, specified in the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) (2000) report, is exceeded 0.5 mSv y−1 at all stations. In the statistical analyzes based on X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) results, positive strong and moderate correlations were found between the average 222Rn concentration and weight percentage (Wt %) of K2O, Na2O, ThO2, ZrO2 oxides and Quartz, Montmorillonite, Albite minerals, respectively. Gamma radiation is correlated with Na2O Wt% content (R2 = 0.7056). A moderately negative correlation was found between the mean 222Rn concentration and temperature, a weak negative correlation with pressure, a weak positive correlation with humidity, and a moderately significant correlation with the presence of granite.

Unraveling the complex interplay between soil characteristics and radon surface exhalation rates through machine learning models and multivariate analysis

This research seeks to elucidate the intricate interplay between soil characteristics and the rates of radon surface exhalation rate. To achieve this aim, Light Gradient Boosting Machine (LightGBM) and eXtreme Gradient Boosting (XGBoost) machine learning (ML) algorithms are employed, supported by Multivariate Analysis (MA). An analysis was performed on a collection of soil samples, examining radon surface exhalation rates and other pertinent properties such as moisture content, particle size distributions, and the concentrations of Ra-226, Th-232, and K-40. The analysis revealed several key factors influencing radon exhalation rates, namely Ra-226 concentration, moisture content, and larger soil particles. To visualize the intricate relationships between these variables, contour plots of experimental and ML-generated data were created. These visual representations demonstrated that elevated soil moisture levels decrease radon exhalation rates. In contrast, higher concentrations of Ra-226 and a greater proportion of large soil particles led to an increase in exhalation rates. This endeavor presents these complex relationships in an accessible manner, furthering our understanding of the factors in radon surface exhalation.MA techniques, including Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA), were initially employed to investigate the complex interactions of soil attributes on radon exhalation. HCA identified three distinct clusters but faced limitations in detecting strong negative impacts. PCA successfully captured these inverse effects, indicating that the first two principal components accounted for approximately 80% of the total variance, primarily attributed to Ra-226 concentration, moisture content, and the percentage of large soil particles. However, neither technique could quantify the effects of soil attributes on radon exhalation rates. LightGBM outperformed XGBoost, but both successfully quantified the impacts of the studied soil characteristics on radon exhalation. Sensitivity analysis confirmed the robustness and accuracy of both models.This study highlights that XGBoost and LightGBM algorithms can effectively quantify radon exhalation rates based on soil characteristics, providing valuable insights for environmental policies, land use planning, and radon mitigation strategies.