Radon Exhalation Rate Research Articles

Risk assessment of radon in soil collected from chromite mines of Khanozai and Muslim Bagh, Balochistan, Pakistan

Radon is an inert gas that can transfer from rock, soil and accumulate in enclosed areas such as dwellings and mines. It is reported that exposure of miners to radon gas and its progenies can cause lung cancer. Therefore, monitoring of radon in underground mines is important to assess the health hazards to the miners. Keeping in view these facts measurement of radon in soil collected from chromite mines of Khanozai and Muslim Bagh, Balochistan was carried out using CR-39 track detector. The concentration of radon in soil collected from chromite mines of Khanozai was ranged 0.67 ± 0.06 to 1.94 ± 0.10 kBq/m3 with an average of 1.23 ± 0.69 kBq/m3 while in case of Muslim Bagh its values ranged from 0.49 ± 0.071 to 2.12 ± 0.11 kBq/m3 with an average of 1.26 ± 0.08 kBq/m3. The average values of radon exhalation rate were 9.95 ± 0.6 and 10.20 ± 0.68 Bq/m2 h from soil collected from chromite mines of Khanozai and Muslim Bagh, respectively. In addition to radon concentration and exhalation rate, radium activity (226Ra) were also calculated. Average values of radium activity for Khanozai and Muslim Bagh chromite mines were found 3.02 and 3.09 Bq/kg, respectively. The values obtained for radon exhalation rate were found below the average value of 57.60 Bq/m2 h recommended by UNSCEAR. Therefore, it is concluded that the mines understudy are safe from health hazards related to radon gas.

Alpha radioactivity level along Tigris River sediments in Baghdad governorate area by using CR-39 SSNTD\u2019s

The alpha activities of sediment samples, collected from selected sites along Tigris River in Baghdad city area from January to November 2015, were measured. The measurements were based on the radon exhalation rate Bq m−1 from the sediment samples, of 10.00 g mass. It was found that the higher calculated uranium contents were observed during winter months from November to January, while the lowest one were during summer months from May to September. This difference was attributed to the nature of the sediment samples and anthropogenic activities that affected ecosystem of the river. Uranium content of the samples was increased ongoing towards south of the city due to the effects of huge human activities. The increase in water level of Tigris River during this period possibly related to the melting of snow in the Turkish mountainous region. Higher water stream can remove sediments from the river bottom; this mechanism will be partially responsible for increasing the radioactivity level at downstream of the river.

A study on radionuclides content and radon exhalation from soil of Northern India

Radioactivity dispersed in indoor environment is a consequence of exhalation of radioactive gas radon from soil, building materials, and rocks containing primordial radionuclide. The health risk for population from the radionuclides and radon exhalation rates of soils from different places in vicinity of Kurukshetra in Northern India is estimated. Radionuclides content and radon exhalation rate of the soil samples are measured using gamma and alpha spectroscopy, respectively. Various doses (absorbed gamma dose and annual effective dose) and associated index (Alpha, Gamma, External, and Internal Radiation Hazard Indices) with radionuclide contents present in soil samples are also estimated. Radiological hazards are calculated by two different approaches; one based on radionuclides content and emanation factor and other on the basis of exhalation rates and room dimensions. The results of radioactivity content and exhalation rates are found below the level recommended by United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Alpha equivalent dose (HE) is also estimated as per the recommendations of UNSCEAR and found well below the safe limit. The study is helpful to determine the soil potential to exhale carcinogenic gas radon at the surface and also for radon and thoron mapping.

Estimation of radon potential through measurement of uranium concentrations in granite geology

The geology of an area can be used as a predictor for radon potential. Granite rock typically contains a high concentration of uranium and subsequent elevated emanation of radon gas. The geology of the western part of the Western Cape Province in South Africa is dominated by granite bedrock but very few studies on radon have been conducted in this area. Uranium concentrations were consequently measured on a large granite hill in the Saldanha Bay area of the Western Cape and a relationship between indoor radon and uranium concentrations was used to model radon potential on the outcrop. Results from granite rich environments in India were modelled in order to extract a relationship between indoor radon concentrations, radon exhalation rates and uranium concentrations. Radon exhalation rates greater than 0.35 Bq/m2h were predicted and estimated indoor radon concentrations in excess of 400 Bq/m3 were also predicted for the hill. The modelled results were compared with indoor radon measurements taken in the town of Paarl in the Western Cape, which sits on the same granite bedrock formation. The predicted radon potential correlated well with the physical measurements.
 Significance:
 
 Extensive in-situ uranium measurements were conducted by utilising a self-developed gamma-ray detection instrument (the GISPI) by means of a unique method.

Experimental study of the effect of seepage on radon exhalation in circular tubular porous emanation media

Radium, which is naturally present in many rocks, decays to the radioactive gas radon, which is then exhaled from the surface of underground tunnels and other underground buildings and is a major source of human exposure to radioactivity. A mathematical model for the migration of radon from a circular tubular emanation medium was established based on the seepage–diffusion migration theory for radon in porous emanation media, such as artificial retaining walls and the surrounding rocks in these locations. An analytical solution for the distribution of radon concentrations and the calculation formula for the radon exhalation rate under steady-state conditions were then obtained. An experimental device was designed to determine the radon exhalation rate under different pressure gradients. The theoretical calculation values for the radon exhalation rate and the total amount of radon exhalation are in good agreement with the experimental results. The radon exhalation rate at the low-pressure side increases with an increase in seepage velocity (pressure difference), while the radon exhalation rate at the high-pressure side is on the contrary. The total amount of radon exhalation increased over time with an increase in the seepage velocity and tended towards a maximum value.

Effect of Grain Size on Radon Exhalation Rate from Calcium Silicate Rocks Using Alpha Track Detector

Radon generated in the earth’s crust enters the pore spaces and transported by diffusion, then released into the surrounding atmosphere. Grain size is one of the important factors that effect on the radon exhalation rate from the soil. Radon emanates through the soil grains into air and diffuses to the atmosphere. The variation in radon concentration and exhalation rate from calcium silicate rock samples with different grain size were measured using Alpha Track Detector. The high value of radon exhalation rate was 43.05 ± 2.17 at gravel size and the lowest value was 8.98 ± 0.85 at mud size. The results indicate that the exhalation rate was increased with increase the grain size of the studied samples. The obtained values of radon exhalation rate for all the samples are found to be under the radon exhalation rate limit reported worldwide, and UNSCEAR. The present study is important to radiological impact assessment of requiring information on the exposure due to natural radiation to protect the environment.

Experimental study of the effect of water level and wind speed on radon exhalation of uranium tailings from heap leaching uranium mines.

Water level and wind speed have important influences on radon release in particle-packing emanation media. Based on radon migration theory in porous media under three water level conditions, an experimental setup was designed to measure the surface radon exhalation rate of uranium tailings from heap leaching uranium mine at different water levels and wind speeds. When the water level was at 0.3 m (overlying depth 0.05 m), radon transfer velocities at the gas-liquid interface were also measured at different wind speeds. Results show that when the water level was equal to or lower than the surface of the sample, the radon exhalation rate increased with increasing wind speed and decreased with increasing water level. When the water level was higher than the surface of the sample, radon exhalation rate of the water surface increased with increasing surface wind speed. The wind speed, however, was less influential on the radon exhalation rate as the depth of the overlying water increased, with a dramatic decrease in radon release. That said, at different wind speeds, radon transfer velocities at the gas-liquid interface were consistent with literature. On the other hand, changes in wind speed had significant influences on the radon transfer velocity at the gas-liquid interface, with the effect less pronounced at higher wind speeds.

Effective radium activity, radon exhalation rate and uranium concentrations in medicinal plants

In the present work, effective radium activity, radon exhalation rates and uranium in medicinal plants have been measured,samples collected from Iraqi markets. Sealed cup technique containing CR-39 solid state nuclear detector was used. Radium concentration varies from (0.0297 ± 0.004) Bq/kg to (0.327 ± 0.126) Bq/kg with an average of (0.142 ± 0.025) Bq/kg. The radon exhalation rate in terms of area varies from (2.287 ± 0.384) μBq/m2.d to (25.193 ± 9.729) μBq/m2.d with an average of (10.986 ± 1.989) μBq/m2.d, while uranium concentrations were ranged from (0.018 ± 0.002) ppm to (0.202 ± 0.057) ppm with an average (0.087 ± 0.002) ppm. The values of radium concentration, exhalation rates and uranium in all the medicinal plants samples were less than the recommended by the Organization of Economic Cooperation and Development (OECD), United Nations and Scientific Committee On The Effects Of Atomic Radiation (UNSCEAR) respectively. The results have revealed that the radium and uranium concentration as well as exhalation rates in studied medicinal plants and the associated exhalation radon does not pose risk to human health.

Progress in the Development of Track Radiometers for Radon Measurements

Radiometers based on solid-state nuclear track detectors, developed for radon measurements in the past two decades, are considered. Devices for measuring the volume activity of radon, thoron, and their decay products and the rate of radon exhalation from various media (soil, water, building materials) are discussed. Significant progress in the development of radiometers for simultaneous measurements of the radon and thoron concentrations and for direct measurements of the concentrations of their decay products is noted.

Determination of Radon Exhalation Rates from Tiles (Marble, Granite and Ceramic) Using LR115 Type II Passive Technique

Exhalation of 222Rn, α-radioactive inert gas, is associated with the presence of 226Ra andit's ultimate precursor uranium in the earth crust. It is a useful quantity to compare the relativeimportance of different materials of tiles (marble, granite and ceramic). Majority of newhouses in Basrah (Iraq) are using tiles. Therefore, studies concerning the determination ofradon exhalation rate from there materials were carried out using LR-115 Type ІІ passivetechnique in this content, the Solid State Nuclear Track Detectors(SSNTDs) with a plasticcontainer('can' technique) were applied .There container were hermetically sealed and storedfor 120 days to attain equilibrium between 222Rn and 226Ra . After exposure to radon, LR115type II detectors were etched in 2.5N NaOH solution at 60°C for 2h. From the measured radonconcentration values , 222Rn exhalation rates were determined. The average values ofexhalation rates for radon has been found of values ( 0.225, 1.529, 16.196 Bq m-2 h-1) formarble, ceramic and granite respectively. Exhalation rates for granite has been found to beseveral times higher than that for marble and ceramic. The results of the measurement hasbeen discussed.

Abnormal High Radon Exhalation Levels on the Mount Beshtau, North Caucasus

The measurements of radon exhalation rate, radon concentration in the air, gamma-doze rate and radium content in soils on the Mount Beshtau were carried out. The very high radon levels were discovered in local zone on the western slope. The radon exhalation rate in the anomalous zone achieves 15,000 mBq/m2s, and the radon concentration in the atmospheric air exceeds 4000 Bq/m3. These levels sufficiently exceed the local background. The extremely high values of radon exhalation rate in the anomalous zone cannot be explained by local sources of radon. Anomalous levels of radon exhalation probably result from radon transport out of fracturing zones with convective air flows. This thesis is confirmed by repeated measurements.

Assessment of radiation risk and radon exhalation rate for granite used in the construction industry

The results of the gamma spectrometry analysis of the 40 samples of highly radioactive granites used in the construction industry in Serbia are presented. Based on the measured activity concentrations of 226Ra, 232Th and 40K, radiological hazard indices, annual effective doses, as well as indoor radon concentration were determined. Calculated indoor radon concentration caused by investigated granite samples in 25% of cases exceeds the upper limit of 300 Bq m−3 recommended by the World Health Organization.

Experimental study on radon exhalation behavior of heap leaching uranium ore column with dilute sulfuric acid.

In order to study the radon release behavior when heap leaching uranium ores with dilute sulfuric acid, unleached uranium ores from a uranium mine in southern China were selected as test samples. Adopting parameters from leaching processes commonly used in uranium mines, a laboratory experiment was carried out for 21days with a one-dimensional acid heap leaching experimental column. The surface radon exhalation rate of uranium ore column was determined by static accumulation method while spraying with deionized water and dilute sulfuric acid. The uranium leaching rate and ore column height for all 21days of the experiment were also measured. The results show that (1) when sprayed with a leaching agent, the surface radon exhalation rate of uranium ore column initially increased with time sharply. After a maximum value was reached, the rate gradually decreased and stabilized. When the spraying stopped, the surface radon exhalation rate of uranium ore column initially decreased, before increasing until it tended to stabilize. (2) During the entirety of the 21-day leaching experiment, the cumulative leaching rate of uranium increased gradually with time. On the other hand, the surface radon exhalation rate of uranium ore column fluctuated, but the leaching of uranium from uranium ores had almost no effect on the radon exhalation rate. (3) There was no linear correlation between the surface radon exhalation rate and the residual height of ore column during leaching, but the collapsing event of ore column was the direct inducing factor of the fluctuation of surface radon exhalation rate.

Measurement of Radon Concentration Using SSNTD in Bartella Region

The alpha-radioactive inert gas Radon exhalation is associated with presence of Radium and its ultimate precursor uranium in the earth crust. Uranium decay deposits radon in soil, which is harmful on human and environment. The exposure of population to high concentration of alpha radioactivity mainly of Radon for a long period leads to lung cancer. The radon activity concentrations, radium contents, radon exhalation rates in twenty one soil samples collected from Bartella region, were measured using the sealed-can technique based on the CR-39 SSNTDs. In the present paper the estimated values for radon activity concentration in air space are in the range 323.2-2424 Bq/m3 with mean value of 1212.7 Bq/m3, the radon concentration in soil sample are 31.66-237.46 KBq/m3 with mean value of 118.83 KBq/m3, the radium contents were found vary between 1.36-10.24 Bq/Kg with mean value 5.11 Bq/Kg, the radon mass exhalation rate vary between 10.34-77.56 mBq/Kg/hr with mean 38.81 mBq/Kg/hr, the radon surface exhalation rate are between 234.2-1756.4 mBq/m2/hr with mean value of 878.6 mBq/m2/hr. All values of the samples under the test are below of permissible values 370 Bq/Kg of radium content and 57600 mBq/m2/hr radon exhalation, recommended by Organization for Economic Cooperation and Development (OECD). Hence the area under investigation is safe as for as health hazards of radium and safe in radiological risks due to radon exposure from the soil.

Evaluation of 222Rn and 226Ra concentrations in cement and limestone of Sheikh Buddin Hill, Pezu, Pakistan using different techniques

ABSTRACTLucky Cement Factory, Pezu is using limestone of Sheikh Buddin Hills as a raw material in cement. Workers of the factory have direct and general public have indirect exposure to radiological hazard due to natural radionuclides present in limestone. To address the radiological hazards, limestone, mixed (limestone+clay) and cement samples were evaluate for concentrations of 222Rn and 226Ra using CR-39, RAD7 and HPGe detectors. Maximum mean values of 222Rn using CR-39 and RAD7 detectors were found 1447 ± 198 and 1416 ± 74 Bq.m−3 in cement samples and minimum were found in 536 ± 122 and 525 ± 45 Bq.m−3 limestone samples, respectively. Maximum mean value of radon exhalation rate of 12.28 ± 1.68 Bq.m−2 h−1 in cement samples was found below the world average value of 57.6 Bq.m−2 h−1. Maximum mean values of 226Ra measured by CR-39 and HPGe detectors were found 24.25 ± 3.35 and 23.6 ± 0.70 Bq.kg−1 in cement samples and minimum were found in 8.98 ± 2.02 and 9.19 ± 0.40 Bq.kg−1 limestone samples, respectively. A positive correlations (R2 = 0.9714) using CR-39 and RAD7 detectors and (R2 = 0.9573) using CR-39 and HPGe detectors were obtained for the concentrations of 222Rn and 226Ra, respectively. Maximum mean value of annual effective dose of 347.78 ± 47.58 µSv.y−1 in cement samples was found below the world average value of 1100 µSv.y−1.

Radon exhalation rate and indoor exposure in a Brazilian coal mine

Radionuclides in mineral coal and related rocks are of great concern to the human health, among them the radon gas, as it has been considered the second largest cause of lung cancer by the World Health Organization (WHO). This paper describes a field and laboratorial study focusing this noble gas in the Amando Simoes PI-08 coal mine, Figueira city, Parana State, Brazil. The average 222Rn activity concentration inside the mine was ~ 227 Bq/m3, whereas the average annual effective dose received by the workers was 1.4 mSv/year, suggesting that it does not offer radon-risks to the human health.

Radon Exhalation Rate and Mean Annual Effective Dose from Radium concentration from Gharraf Canal and Its Some Branches in Thi Qar Governorate (Iraq)

Radon Exhalation Rate and Mean Annual Effective Dose from Radium concentration from Gharraf Canal and Its Some Branches in Thi Qar Governorate (Iraq)

The Effect of Temperature Gradients on the Exhalation Rate of Radon Generated by Building Materials

Abstract There is increasing interest in indoor air quality studies. The effect of exhaled radon from soil, walls and ceilings has well-known consequences on human health, so the importance of modelling has been established. The present paper examines radon exhalation, on the one hand, only in the case of diffusion and, on the other hand, diffusion and advection. Comparing the results of the two test types, we can determine how significant the effect of temperature gradients on radon exhalation is. For a broader investigation, we performed the parametric tests on several types of material, wall thickness and radon concentration.

Estimation of Radon Exhalation Rate, Radium Activity and Uranium Concentration in Biscuit Samples in Iraq

Introduction: Radioisotopes are naturally the main sources of human exposure to external and internal radiation. Biscuit is a type of food that is widely distributed in all markets, especially in the markets of Iraq. Therefore, the current study aimed to measure the radiation level of some nuclei in biscuit samples and determine the radiation risks that may be caused by this snack. Material and Methods: This study aimed to evaluate the concentration of alpha radiation activity in 22 different samples of biscuits collected from the markets in Iraq. The analysis of radium activity and radon exhalation rate was performed by employing alpha-sensitive CR-39 plastic track detectors. Results: The effective radium values ranged within 23.312-200.44 Bq/kg with a mean value of 58.927 Bq/kg. Radon emission values for the mass unit was within the range of 0.172-1.515 𝐵𝑞/kg.h, with a mean of 0.445 Bq /kg.h, while radon emission values for the surface unit were 3.988-34.3 𝐵𝑞 /𝑚2.h, with a mean of 10.081 Bq /m2.h. The uranium concentrations found in these samples were within the range of 0.02-0.172 ppm with a mean value of 0.05 ppm. Moreover, there was a direct relationship between radium activity and radon exhalation rate. Additionally, the findings showed that uranium correlated positively with radium activity. Conclusion: The results of the present study were within internationally permissible limits. Therefore there is no risk of consumption of biscuits on human health. However, we must use modern techniques and techniques to reduce radiation risk.

Integrating radon and thoron flux data with gamma radiation mapping in radon-prone areas. The case of volcanic outcrops in a highly-urbanized city (Roma, Italy)

An integration of laboratory radon and thoron exhalation data with gamma radiation mapping is applied to assess the geogenic radon and the exposure of people to natural radiation in a highly-urbanized city (Roma, Italy). The study area is a protected territory where ignimbrites from Colli Albani volcano and alluvial sediments largely crop out. A map of total gamma radiation, a gamma transect across Caffarella valley and 9 vertical gamma profiles have been carried out, showing that the main control of gamma levels is, of course, the lithological nature, without neglecting the simultaneous effect of other parameters such as slope morphology, erosion/weathering processes, occurrence of sinkholes or underground tunnels. The surveys allowed to distinguish the medians of ignimbrites (from 816 ± 16 cps to 936 ± 19 cps) from that of alluvial materials (611 ± 14) cps), but showed also that alluvial sediments with anomalously high radioactivity (769 ± 14 cps) can be locally recognized, providing valuable information on the interaction between sedimentation and erosion in fluvial valleys. Total gamma activity was converted into absorbed gamma dose rate ranging from 0.33 to 0.38 μSv/hr. Outdoor Annual Effective Dose Equivalents were also estimated between 0.58 and 0.67 mSv y−1.Laboratory radon and thoron exhalation rates of collected material are positively correlated with gamma radiation. Volcanic and alluvial sediments are well-discriminated. The correlation between the two variables is evident, but not robust because of the variable concentration of 40 K, which is not contributing to radon and thoron exhalation rates. Anomalous data of soil samples located at the foot of a slope can be interpreted as due to reworking and accumulation processes. Similar gamma radiation data documents analogous concentration of radon and thoron parent-nuclides, but coexisting different radon and thoron exhalation rates provides an additional information on different grain size distributions which can be considered as a proxy for soil gas permeability.The integration of gamma mapping and radon and thoron exhalation measurements is a very useful tool to assess people exposure to natural radiation, in terms of dose rates and potential indoor radon. Gamma mapping, which provides data on the radiation source (the bedrock) is fast and not expensive. It allows to obtain very detailed pictures of a study area, but it needs to be combined with laboratory determination of radon and thoron release in order to definitely and correctly interpret variations of gamma signal. Furthermore, laboratory determination of soil radon exhalation gives information on the release of radon and is a good proxy for soil gas permeability. It has the great advantage over in-situ measurements of gas flow not to be influenced by seasonal pedoclimatic parameters and is affected by lower analytical uncertainties. These data are thus reproducible and precise and can be used to estimate potential radon hazard, which is the main source of exposure and thus the most important parameter for human protection from environmental radioactivity.