Exhalation Rate Research Articles

Assessment of radon exhalation rates, effective radium content and radiological exposure dose, of coal and rocks in Tiru Valley Coal Field, India using track etched technique

In this study, the outcomes of assessments of radon exhalation rates for both mass and surface, radium content and annual effective dose from 45 numbers of geological samples in Tiru Valley Coal Field area are presented. The nuclear track detector LR-115 (II) of bulk etch rate, VB = 4 μm h−1 with a spark counter to archive alpha track density of radon was used to measure radon exhalation rate from the samples and to assess radiological exposure in the coalfield area, which has significant geological characteristics. In this work, the surface exhalation rates for coal, carbonaceous shale and sandstone samples have been estimated to be in the range of 217.4–659.9 mBq m−2 h−1, 234.0–381.1 mBq m−2 h−1 and 337.1–741.4 mBq m−2 h−1, respectively. The mass exhalation rates for coal, carbonaceous shale and sandstone samples varied in the range of 6.5–19.8 mBq kg–1 h−1, 7.0–11.4 mBq kg–1 h−1, and 10.1–22.2 mBq kg–1 h−1, respectively. The radium contents have been found to vary in the range of 6.7–20.3 Bq kg−1, 7.2–11.8 Bq kg−1 and 10.4–22.9 Bq kg−1 for coal, carbonaceous shale and sandstone respectively. The annual effective doses related to the inhalation of radon from the exposure to the samples have been estimated to be in the range of 15.8–47.9 μSv y−1, 17.0–27.7 μSv y−1 and 24.5–53.8 μSv y−1 for coal, carbonaceous shale and sandstone respectively. In this investigation, the lifetime fatality-risks have also been assessed. The values were generally higher in rock samples than in coal. However, the findings have shown that the obtained values are within the internationally accepted recommended values.

Study on the pore structure and radon release characteristics of coal in northern China

Identifying the release characteristics of radon (Rn-222) in coal mines is critical preventing cancer risks for coal miners and coal fires. The present investigates the pore structure characteristics of coal samples from eleven coal mines in northern China, using low-temperature nitrogen adsorption (LTNA) test, combined with the radon exhalation rate in coal. The findings of the study reveal that the N2 adsorption isotherms of all the coal samples fall under the inverse S type, with micropores dominating in low-rank coals and mesopores dominating in the medium and high-rank coals, due to the separation of organic matter and quartz by shrinkage of micro-components and the orderly arrangement of aromatic rings as a result of ring condensation and thermal cleavage. The pore diameters of coal samples show similar distribution characteristics for sizes >2 nm, represented by a single peak near the pore diameter of 3 nm. Ash yield controls the mesopore and micropore volumes of medium and high-rank coal samples. The radon emission rate displays positive linear correlation (r2 = 0.87) with micropore volumes of analyzed coal samples due to the infillings of free radon in micropores. The radon element is derived by uranium decay, which causes a greater radon exhalation rate of coal mines in areas near the uranium mines. The results of the present study could be helpful to understand the influence mechanism of radon emission processes in coal, which provides an important basis for reducing cancer risks for coal miners and predicting coal fires.

Radon concentration and exhalation rate for granitic rocks, Central Eastern Desert, Egypt

The present work deals with radon pollution arising from granitic rocks using an Alpha Guard radon monitor. Forty-four granitic samples were collected from five sites located in the Central part of the Eastern Desert of Egypt. The minimum to maximum concentration of radon for the rocks of Gebel (mountain) El-Missikat MS, El-Gidamy GD, RieEl-Garra RG, El-Aradiya AR, and Kab-Amira KA were 49,597 ± 8773 to 236,029 ± 22,397 Bq m−3, 39,658 ± 8341 to 188,666 ± 20,545 Bq m−3, 39,854 ± 7645 to 91,393 ± 13,429 Bq m−3, 45,951 ± 9488 to 121,935 ± 14,869 Bq m−3, and 33,209 ± 6989 to 251,398 ± 25,759 Bq m−3, respectively. The surface and mass exhalation rates, the emanation coefficient, and annual effective dose (indoors) were calculated for all the studied samples. The average value of radon concentration in the collected samples was higher than the national reference level of 300 Bq m−3 recommended by ICRP corresponding to an annual effective dose of 4 mSv at work and 14 mSv at home. The measured values for the rock samples studied in the five sites surpassed the world average of soil in areas with normal levels of radioactivity. The MS granitic samples showed a potential radiological risk for human beings, therefore, it is important to carry out a detailed monitoring program for dose assessment.

Evaluation and measurement methods for the surface radon exhalation rate of buildings

Half of the natural radiation dose to the human body comes from indoor radon and its progeny, inhaling of which plays a key role in the development of lung cancer. Given the relationship between the radon exhalation rate (RnER) and the indoor radon concentration, accurate determination and control of the former directly affect the control and protection of the latter. In this study, a method was developed to estimate the actual RnER of building walls through building material samples. The surface RnER of the wall of any thickness that was constructed of any building material could be calculated by its intrinsic RnER value and radon diffusion length, which could be obtained by measuring the RnER of the pre-treated building material sample models through the activated carbon box-γ spectroscopic method. The experimental results indicated that the deviation between the calculated wall surface RnER of the building and the measured wall surface RnER of the building was <5.1%. Therefore, the intrinsic RnER of building materials could be regarded as an evaluation index for the RnER of buildings.

Effect of simulated earthquake loading on radon exhalation from uranium tailings dam.

Uranium tailings sand will continuously release radon-222. When the external condition changes, the exhalation of radon will also change. Thus, radon is being recommended as a tracer for dam damage assessment. When an earthquake is simulated on the uranium tailings dam with a shaking table test and the change in radon concentration is measured, it is observed that the earthquake causes micro-fissures in the uranium tailings dam, which aggregate to form fractures. During the process, the radon concentration will climb dramatically, as will the radon exhalation rate. To verify that the radon monitoring date is accurate, the acceleration response, surface displacement, and interior displacement are all monitored. The results show that radon can be utilized as a tracer to evaluate uranium tailings dam damage.

Radon and Exhalation Rate Measurement of Soil Samples in Al-Amiriya Area in Baghdad Governorate Using a Nuclear Track Detector

Abstract Radon is the most dangerous natural radioactive component affecting the human population, since it is a radioactive gas that results from the decomposition process of uranium deposits in soil, rocks, and water, and it is damaging both humans and the ecosystem. The radon concentrations and exhalation rate in soil samples from various locations were determined using a passive approach with a CR-39 (CR-39 is Columbia Resin #39; it is allyl diglycol carbonate C12H18O7) detector in Amiriya region in Baghdad Governorate. The average values of radon concentrations are ranged from 47.3 to 54.2 Bq·m−3. From the obtained results, we can conclude that the values of all studied locations are within the allowed levels. This research can be utilized to examine any variations in the radioactive baseline level in our homes and regions as well as to identify any hazardous radiation that could harm humans.

Soil radioactivity levels and radiation exposure to the population in Aswan and Abu Simbel areas, South of Egypt

Gamma-ray spectrometer and Lucas cell were used to evaluate the activity concentrations of 226Ra, 232Th, 40K, and 222Rn mass exhalation rates for 37 topsoil samples from different sites in Aswan city, Aswan-Abu Simbel highway, and Abu Simbel village, south of Egypt. The average activity concentration of 226Ra, 232Th, and 40K was 23.3 ± 1.7, 21.1 ± 1.2, and 283.4 ± 22.3; 21.2 ± 1.7, 15.2 ± 1.0, and 89.4 ± 10.5; 29.0 ± 2.2, 26.3 ± 1.5, and 79.5 ± 9.7 Bq kg−1 for soil from Aswan city; Aswan-Abu Simbel highway; and Abu Simbel village, respectively. Activity ratios for the studied radionuclides were calculated, and 232Th/226Ra ratios in most of the sampling sites were <1.1 (natural equilibrium ratio). The mass ratio of Th/K was computed, and the results showed the presence of three main types of clay minerals (montmorillonite, kaolinite, and heavy thorium-bearing minerals) in the studied areas. Radon measurements showed that soil from Aswan city has the highest average value of 222Rn mass exhalation rate (20.6 ± 1.7 mBq kg−1 h−1). The ambient dose equivalent rates were measured in situ using the portable survey meter, and the obtained values showed no significant differences between the studied areas. In general, the results indicate that the studied areas can be considered as areas with normal background radiation levels, and therefore the risks of exposure to natural radiation are minimal.

Radiological assessment of urban soil samples in the residents of a central Anatolian volcanic province, Turkey

ABSTRACT The concentration of natural and anthropogenic radionuclides, emanation fraction (EF), and mass (χM) and area (χA) exhalation rate of 222Rn in urban soil samples collected from dwelling areas in Nevşehir city located in a region known as the central Anatolian volcanic province of Turkey were determined using gamma-ray spectroscopy. The average activity concentrations of 226Ra, 228Ra, 40K and 137Cs were measured as 60.2 ± 3.8, 50.1 ± 2.8, 631.0 ± 29.7 and 5.5 ± 0.4 Bq/kg, respectively. The average concentration of 222Rn in soil and air was estimated as 27 kBq/m3 and 84 Bq/m3, respectively. The average values of EF, χM and χA were found as 20%, 25.4 μBq/kg⋅s and 20.2 mBq/m2⋅s, respectively. The average values of outdoor absorbed gamma dose rate, external and internal annual effective dose and lifetime cancer risk estimated for radiological assessment were found as 85 nGy/h, 104 µSv/y, 797 µSv/y and 4.1 × 10−4, respectively.

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 plastering and paints on radon exhalation rate and radon effective dose from fired bricks

Effect of plastering and paints on radon exhalation rate and radon effective dose from fired bricks

Solidification of uranium mill tailings by MBS-MICP and environmental implications

Uranium mill tailing ponds (UMTPs) are risk source of debris flow and a critical source of environmental U and Rn pollution. The technology of microbial induced calcium carbonate precipitation (MICP) has been extensively studied on reinforcement of UMTs, while little attention has been paid to the effects of MICP on U & Rn release, especially when incorporation of metakaolin and bacillus subtilis (MBS). In this study, the reinforcement and U & Rn immobilization role of MBS -MICP solidification in different grouting cycle for uranium mill tailings (UMTs) was comprehensively investigated. The results showed that under the action of about 166.7 g/L metakaolin and ∼50% bacillus subtilis, the solidification cycle of MICP was shortened by 50%, the solidified bodies became brittle, and the axial stress increased by up to 7.9%, and U immobilization rates and Rn exhalation rates decrease by 12.6% and 0.8%, respectively. Therefore, the incorporation of MBS can enhance the triaxial compressive strength and improve the immobilization capacity of U and Rn of the UMTs bodies solidified during MICP, due to the reduction of pore volume and surface area, the formation of more crystals general gypsum and gismondine, as well as the enhancing of coprecipitation and encapsulation capacity.

Mathematical Modelling to estimate Radon exhalation rates: A study on soil samples from Pangi valley of Chamba district, Himachal Pradesh, India

Radon being radioactive gas is the main source of radiation exposure in the environment. When inhaled, it may cause carcinogenic diseases due to alpha emission during the radon decay, as alpha particles may damage respiratory and alveolar epithelial cells. Thus continuous investigation of the radon level in the environment is always required. In the same, correlation between concentration of radium with radon exhalation rates in the soil samples may be very helpful to know the variation of the radon level. In present study soil samples have been collected randomly from various locations of Pangi Valley of Chamba district, Himachal Pradesh, a northern hill state of India. Radon exhalation rates in collected samples have been measured using the closed can technique in correlation to different soil parameters. Radon mass exhalation rate in soil samples have found to vary from 0.018 to 0.179 Bq kg-1 h-1 with an average value of 0.082 Bq kg-1 h-1 and area exhalation rate from 0.56 to 5.42 Bq m-2 h-1 with an average of 2.47 Bq m-2 h-1. A Mathematical model has been developed using soil parameters viz. bulk density, porosity, emanation rates, diffusion coefficients etc. and use to estimate the radon exhalation rates in soil samples. A strong positive correlation has been obtained between the theoretically estimated and experimentally measured obtained values.

Effect of Carbonation on Radon Exhalation Rate in Concrete

Effect of Carbonation on Radon Exhalation Rate in Concrete

222Rn Activity Concentration Measurement and its Radiological Risks in the Environment of Barserin Village, Erbil-Iraq

222Rn Activity Concentration Measurement and its Radiological Risks in the Environment of Barserin Village, Erbil-Iraq

The concentrations of radon in the marine sediments of Ra's Al-Besha, Northern west of the Arabian Gulf

Pollution is the common problem in the biosphere and the pollution in the marine habitat was noticed more in the present scenario. There are two ways for the pollution marine habitats. They are Naturally Occurring Radioactive Material (NORM) and Artificially Radionuclides (TENORM). Methods used to estimate the concentration of radionuclides are passive (can technique) which use CR-39 and active with different ways. The passive and active methods are different in the exposure time for detectors. The study area Ra's Al-Beshais lie in the northern west of the Arabian Gulf. The obtained average value of radon concentration with arithmetic mean value of 400.7±198 Bq m-3 by the passive method. The mass exhalation rate in sediment samples under study with average value 0.1617 Bq.kg-1.h-1. This value was acceptable worldwide and safe to use

Radiometric and radon exhalation rate analysis of Gahirat marble, Chitral Khyber Pakhtunkhwa, Pakistan

Radiometric and radon exhalation rate analysis of Gahirat marble, Chitral Khyber Pakhtunkhwa, Pakistan

Regulated Monosyllabic Talk Test vs. Counting Talk Test During Incremental Cardiorespiratory Exercise: Determining the Implications of the Utterance Rate on Exercise Intensity Estimation.

PurposeWhen utilizing breathing for speech, the rate and volume of inhalation, as well as the rate of exhalation during the utterance, seem to be largely governed by the speech-controlling system and its requirements with respect to phrasing, loudness, and articulation. However, since the Talk Test represents a non-standardized form of assessment of exercise intensity estimation, this study aimed to compare the utterance rate and the estimated exercise intensity using a newly introduced time-controlled monosyllabic Talk Test (tMTT) versus a self-paced Counting Talk Test (CTT) across incremental exercise stages and examined their associations with the exercise physiological measures.MethodsTwenty-four participants, 10 males and 14 females (25 ± 4.0 yr; 160 ± 10 cm; 62 ± 14.5 kg) performed two sessions of submaximal cardiorespiratory exercise at incremental heart rate reserve (HRR) stages ranging from 40 to 85% of HRR: one session was performed with a currently available CTT that was affixed to a wall in front of the participants, and the other session was conducted with a tMTT with a 1-s inter-stimulus interval that was displayed from a tablet. In each session, the participants performed six stages of exercise at 40, 50, 60, 70, 80, and 85% HRR on a treadmill and were also asked to rate their perceived exertion based on Borg’s 6 to 20 Rating of Perceived Exertion (RPE) at each exercise stage.ResultsThe newly designed tMTT significantly delineated all the six stages of incremental exercise (p ≤ 0.017), while CTT could only delineate exercise stages at 60, 80, and 85% HRR. However, in estimations of exercise intensity, the tMTT demonstrated only moderate associations with HRR and Borg’s RPE, similarly to the CTT.ConclusionIf the purpose of exercise monitoring is to detect the intensity of light, moderate, and vigorous exercise intensity, the tMTT could be more universally applicable. However, due to its larger variability of speech rate across exercise intensities, the time-regulated approach may alter the speech breathing characteristics of the exercising individuals in other ways that should be investigated in future research.

Radon exhalation from temperature treated loess

Radon gas is a cancer risk and exists naturally in certain soils, such as loess, which is an important raw earth construction material in arid regions such as northwestern China and southern USA. Accordingly, the radon exhalationed from building materials is of increasing concern; however, there is little research on radon exhalation from loess. In this study, the pore structure and radon exhalation characteristics of heat-treated loess were investigated by nitrogen adsorption tests, swept surface electron microscopy, and radon measurements. The rate of radon exhalation increases linearly with temperature until 400 °C and then decreases exponentially. Changes in the internal pore structure (pore type, surface morphology, and specific surface area) of loess are strongly correlated with the radon exhalation rate. The volume of micropores (<2 nm diameter) is an important influence on radon exhalation ability, which is closely related to the fractal dimension of the micropore structure after heating. The results provide guidance for predicting the radiation risk posed by radon diffusing from loess.

A novel Sr2Nd8(SiO4)6O2 glass-ceramics for rapid immobilization of FP and An3+ co-doped uranium tailings by microwave sintering: mechanism and performance

Oxyapatite (general formula:A2IA8II(BO4)6O2) is a potential material for immobilization of nuclear waste. Here, a novel Sr2Nd8(SiO4)6O2 glass-ceramics (GCs) derived from uranium tailings were synthesized by consecutive microwave sintering technology at 1200 °C for simultaneous immobilization of simulated bivalent fission product (FP) Sr and trivalent actinide (An3+) Nd. Sr and Nd were successfully immobilized into A2I and A8II acceptor sites of oxyapatite respectively, and glass structures. The phase evolution, microstructure, physical property, and radon exhalation of as-prepared sintered forms were systematically investigated by XRD, FT-IR, SEM-EDS, TEM, and RAD7 radon meter. The experimental results demonstrated that the ultimate solid solubility of Sr reached 25 wt.%, while Nd exceeded 30 wt.% at 1200 °C. Importantly, the solidified samples exhibited homogenous and dense microstructure, and the radon exhalation rate improved with the increase of pore. It was indicated that oxyapatite glass-ceramics could be a potential matrix for the simultaneous immobilization of bivalent FP and An3+.

Measurements of Radon Concentrations in Some Dried Fruit and Grain Samples by (CR-39) Nuclear Track Detector

The purpose of this study was to measure the radon concentration of some dried fruit and grain samples which were consumed as a meal. This is performed by counting the alpha tracks emitted from radon by exposing the CR-39 detector. Measurements indicated that the highest concentration of radon in dried fruit samples was in dried coconut sample 69.89247 Bq/m3, and the lowest concentration of radon was in figs 50.40323 Bq/m3, while the highest concentration of radon was in grain samples in oats was 61.82796 Bq/m3, The lowest concentration of radon was in Iraqi bulgur was 48.3871 Bq/m3, These results are due to the type and characteristics of the soil. Also shows that the behavior of the surface exhalation rate is higher than the mass exhalation rate.The concentration of radon gas and the rate of exhalation of radon for samples of Dehydrated fruit and cereals are within the permissible global limit, and eating these foods will be healthy and safety for the public.