Measurement Of Radon Exhalation Rate Research Articles

Measurement of radon exhalation rate and radiation doses in fly ash samples.

Coal based thermal power plants contribute about ~ 72% of the power generation in India. Indian coal is of bituminous type, having a high ash content with 55-60% ash. Due to considerable environmental importance the collected fly ash has become a subject of worldwide interest in recent years. In the present study radon exhalation rate and the activity concentration of 226Ra, 232Th and 40K radionuclides in fly ash samples from Kasimpur Thermal Power Plant, Aligarh, Uttar Pradesh, India have been measured by 'Sealed Can technique' using LR-115 type II detectors and a low-level NaI (Tl)- based gamma-ray spectrometer, respectively. Radon exhalation rate has been found to vary from 57.1±5.3 to 119.4±7.7 mBq m-2h-1 with an average value of 87.3±5.8 mBq m-2h-1. Activity concentration of 226Ra ranged from 20.0±8.5 to 30.0±9.7Bqkg-1 with an average value 23.4±9.0Bqkg-1, 232Th ranged from 17.0±9.9 to 69.0±13.8Bqkg-1 with an average value of 46.5±12.1Bqkg-1 and 40K ranged from 130.0±7.2 to 332.0±11.1Bqkg-1 with an average value of 177.0±8.1Bqkg-1.

Novel approaches for accurately measuring radon exhalation rate and mechanism interpreted by numerical simulation

Measurements of radon exhalation rate using traditional methods can be affected by back-diffusion or differential pressure in the accumulation chamber, resulting in deviations between the measured and the true values. To obtain an accurate radon exhalation rate for evaluation of radon-risk regions, two novel approaches of measurements based on traditional methods were proposed. Repeated experiments were implemented on a self-designed stainless cylindrical vessel filled with uranium tailings sand. The measured radon exhalation rates on average were 0.51 ± 0.02 and 0.52 ± 0.02 Bq m−2 s−1 for the two proposed methods, with 0.02% and 0.04%, respectively, deviations from the theoretical value. In addition, numerical techniques were employed to interpret the defects of traditional methods and mechanisms of proposed approaches to measure accurate values. Two novel approaches have significantly reduced the impact of back diffusion and differential pressure inside the chamber and consumed less time.

A new model to accurately measure the radon exhalation rate from soil using AlphaGUARD

Radon exhalation rate from soil is a critical factor in evaluating environmental radon levels. However, AlphaGUARD PQ2000PRO may have some sensitivity towards thoron, which can have a significant impact on radon measurement. The traditional radon exhalation models generally ignore the presence of thoron, leading to an overestimation of the radon exhalation rate from soil. To handle this issue, a new model was proposed based on an analysis of several previous studies on radon exhalation theories. To prove the feasibility of the model, the radon exhalation rate measurements were performed by two different types of detectors-AlphaGUARD PQ2000PRO and RAD7. The radon exhalation rate obtained by using the new model is in good agreement with that obtained by using the theoretical model of radon exhalation of RAD7 within one standard error. This new model can be applied to accurately measure radon exhalation rate from soil by the PIC detector (PQ2000PRO).

Comparison of radon exhalation rate measurements on reference device in open and closed loop by AlphaGUARD in flow-through mode.

Radon-222 (Rn-222) exhalation rate is vital for estimating radiation risk from many kinds of materials. AlphaGUARD measures the radon concentration based on the ionization chamber principle, which is currently recognized as a reference instrument to measure radon. In China, measurements of radon exhalation rate are performed by AlphaGUARD operated in flow-through mode on a reference device to verify measurement accuracy. These measurements are performed in both open and closed loop. AlphaGUARD can fast rapidly the variation of the radon concentration in the chamber, which is tightly pressed against the surface of the medium to accumulate the exhaled radon. When the model is used to obtain the radon exhalation rate, the radon exhalation rates obtained by nonlinear data fitting on the measured radon concentrations are similar to the reference value of the device. The difference of radon exhalation rate values of six measurements is small.

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

Measurement of radon exhalation rate from building materials: The case of Highland Region of Ecuador

Exposure to 222-Radon (Rn) usually occurs in closed environments as effect of the Rn exhaled from building materials, soil or water. While building materials provide a protection barrier to outdoor natural radiation (terrestrial and cosmic), their radionuclide composition could increase the indoor Rn exposure. In fact, the Rn exhalation of building materials is of great importance from the viewpoint of mitigation and public health in very specific conditions. This work presents the Rn exhalation rates of 40 building materials (concrete blocks, clay brick, granite and concrete samples) produced and used in Ecuador, as well as the effective dose for a reference dwelling. Rn concentration measurements were performed using the closed chamber method and a RAD7 equipment. The resulting Rn exhalation rates were found to be in the range from 0 to 7.83 Bq·m-2·h-1. The highest surface exhalation rate was detected in granite samples, while clay bricks show Rn exhalation below the minimum detection level (0.05Bq·m-2·h-1). In the reference dwelling, the effective dose rates caused by Rn exhalation from building material range from 0.019 up to 0.112 mSv/y. However, the effective dose rate depends on the exposure time and quantity of granite used. Our results could be of immediate help to choose suitable building materials to ensure a safe indoor environment for the dwellers.

The results of long-term simultaneous measurements of radon exhalation rate, radon concentrations in soil gas and groundwater in the fault zone

The regular monthly radon measurements were carried out in the fault zone on the Western slope of the Beshtau magmatic massif (North Caucasus). The radon exhalation rate from the soil surface, as well as radon concentrations in soil gas at a depth of 0.5 m and in groundwater discharged at a spring located nearby have simultaneously been measured. High seasonal fluctuations in radon exhalation and radon concentration in soil gas, characterized by highs in summer and lows in winter, were registered. In summer, the radon exhalation reached 23.8 Bq m−2s−1, and the radon concentration in the soil gas reached 166 kBq m−3. In winter, both the radon exhalation and the radon concentration in the soil dropped to 0.025 Bq m−2s−1 and <3 kBq m−3, respectively. The concentration of radon in ground water varied over the year in a relatively narrow range (100–210 Bq l−1), and there were no seasonal fluctuations. A sharp increase in soil radon and radon exhalation in spring and a fall in autumn are timed to the moments when the temperature of the atmospheric air becomes, respectively, higher and lower than the temperature of the rock massif. Both the soil radon concentration and the radon exhalation show a close correlation with the temperature of atmospheric air, but in the first case the relationship is linear, and in the second – exponential. The obtained data confirm the assumption that the seasonal radon variations are caused by atmospheric air circulation in the shallow area of the fault due to the temperature difference between the atmosphere and the rock massif.

Measurement of Radon Exhalation Rate, Annual Effective Dose and Radium Activity from Marine Sediments Samples Collected From Abian Beach, Aden Gulf, Yemen

The behavior of radon in marine sediments collected from Abian beach, Abian Governorate, Aden Gulf, Yemen, was studied by using Alpha Guard PQ2000 PRO radon detector. The activity concentration of radon in the sediments was found to be ranging from 64.84 to 166.93±11.85Bq.m^-3 with mean value 103.88±8.80Bq.m^-3. The radium content in the sediments ranged from 20.01 to 56.06Bqkg^-1 with mean value 33.51Bqkg^-1, while the area exhalation rate of ²²²Rn ranged from 6.73 to 18.49Bqm^-2h^-1 with mean value 11.22Bqm^-2h^-1 also the mass exhalation rate of ²²²Rn ranged from 0.151 to 0.424Bqkg^-1h^-1 with mean value 0.253Bqkg^-1h^-1, respectively for the studied samples of marine sediments. The annual effective dose was found to be ranging from 1.63 to 4.21mSvy^–1, with an average of 2.62mSvy^–1. Average value of radon concentrations from marine sediments samples were compared with other literature values.

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.

Measurement of radon exhalation rate in various building materials used in Morocco

Measurement of radon exhalation rate in various building materials used in Morocco

Study on the Influence of Radon Collector Parame

Accurate measurement of radon exhalation rate of building materials plays an important role in controlling indoor radon concentration. In order to achieve rapid and accurate measurement of radon exhalation, the influence of the volume, base area and pumping flow rate of radon collector on radon exhalation rate was studied to optimize the measurement parameters of radon exhalation rate and improve the measurement efficiency of radon exhalation rate. The study has shown that the larger the volume of radon collector is, the longer the radon concentration equilibrium time will be when radon exhalation rate is measured with constant pumping flow rate and surface precipitation rate, while the influence of the volume of radon collector on the equilibrium radon concentration can be neglected, but there is a specific linear relationship between the equilibrium radon concentration and the base area of radon collector. When the radon exhalation rate is measured with constant volume and base area of radon collector, the higher the pumping flow rate is, the shorter the radon concentration equilibrium time is and the smaller the equilibrium radon concentration is. When the radon exhalation rate is 3.9Bq∙m^-2∙s^-1 in the experiment, the optimum volume of radon collector is 2.1×10^-3m³, the optimum base area is 3.46×10^-2m^-2, and the optimum pumping flow rate is 1.349×10-5m3/s. The measurement parameters of the radon exhalation rate, such as the best volume and base area of radon collector and the pumping flow rate can be obtained for different radon exhalation rates through this optimization method.

Measurement of radon exhalation rate in various building materials used in Morocco

Measurements of radon surface and mass exhalation rates were made for 35 types of building material samples frequently used in Morocco. In this survey, we used the Can technique, containing CR-39 detectors, to estimate the radon exposure from building materials. The surface and mass exhalation rates ranged from 37.92 mBq−2 h−1, 3.05 mBq kg−1 h−1 to 1545.60 mB q m−2 h−1, 43.14 mBq kg−1 h−1, with an average of 271.4192 mBq m−2 h−1 and 10.23 mBq kg−1 h−1, respectively. All the values of effective radium content and effective dose were calculated and they were within the safe limit in all samples studied.

Measurement of Radon Exhalation Rates from Different Rock Types and Construction Materials (Gaza Strip, Palestine)

Indoor radon increases the health hazard due to long-term exposure. Most building materials of natural origin contain small amount of naturally occurring radioactive materials. The building materials of natural origin reflect the geology of their site origin. This study was carried out to assess the radon activity concentration in rock and building materials used in construction purposes in the Gaza Strip, southwestern of Palestine. Fourteen different construction materials of imported (international) and local origin were tested, using solid state nuclear track detectors (CR-39). After 55 days of exposure, CR-39 detectors were etched chemically and then counted under an optical microscope. The radon concentration level of studied samples ranges from 94.4 to 642.5 Bq/m3. The sands (from north of Gaza Strip), black cement, gray granite and the marble show relatively highest levels with values about 642.5, 285.0, 283.6, and 257.2 Bq/m3, respectively. These values are above the international standard limits, and they are not safe for use in construction purposes. According to Ubeid and Ramadan (2017), the highest value in sands are referred to black sands, agricultural run-off and urban areas, discharges from mining activities, factories and municipal sewer systems, leaching from dumps and former industrial sites. While, the high value in gray granite is related to high percentage of silica and potassium contents, the high value of radon concentration in the marble is interpreted to high contents of organic matter in the original limestone before the metamorphism. On the other hand, values on radon concentration in the waste-dust of marble and granite from industrial quarry were 399.7 and 257.2 Bq/m3, respectively. They were above the international standard limit, and generally the ambient is not safe for workers.

A study on natural radioactivity and radon exhalation rate in building materials containing norm residues: preliminary results

This paper contains preliminary results of a study on the physical and radiological characterization of concrete samples containing NORM. The natural radionuclides content in term of 226Ra, 228Ra, 232Th, 40K and the radon exhalation rate of the samples were determined. Two series of samples of concrete were prepared: samples belonging to both series were made of the same basic components (Portland cement CEM I 42,5R as binder, aggregate and plasticizer) but different amount of NORM residues and mineral additives were used.The concrete samples were characterize in term of absolute density, permeability, total and open porosity. The radiological content was evaluated by using gamma spectrometry and the radon exhalation rate measurements were performed using the dynamic method. Moreover, the Activity Concentration Index (I), introduced by the 2013/59/Euratom Directive, has been used in order to evaluate if concrete samples could exceed the reference level for effective dose due to gamma radiation in building materials.

Setup and procedure for routine measurements of radon exhalation rates of building materials

A practical procedure and the necessary setup for routine measurement of the exhalation rate of 222Rn from building materials are described. The setup comprises a continuous radon monitor, based on an ionization chamber, and a relatively large-volume accumulation chamber. The experimentalist can interact with the setup in real time via a PC. Therefore it is possible to determine the exhalation rates by determining the optimum accumulation time before the effects of back-diffusion and radon decay set in. This, in turn, reduces the time required to test a sample and makes the setup useful for routine measurements. The exhalation rate values (Bq m−2 h−1) for selected building materials made from gypsum, marble, ceramic, and granite were found to be 1.63, 2.29, 3.99 and 5.39 Bq m−2 h−1, respectively. The optimal test-times for the samples ranged from 9 to 19 h.

Preliminary assessment, by means of Radon exhalation rate measurements, of the bio-sustainability of microwave treatment to eliminate biodeteriogens infesting stone walls of monumental historical buildings.

The main purpose of the work described in this paper has been to establish the protocol for a new non-disruptive technique of intervention, based on microwave treatment, for cleaning operations on monumental historical buildings, to eliminate biodeteriogens infesting stones. Non-destructive methods in the cleaning operations, should not only preserve the physical integrity, the chemical-mineralogical and structural identity of materials, but, when the exhalation of pollutant agents (like for example Radon gas) from building materials is considered, also, make the indoor air quality (IAQ) levels healthy. Therefore, one of the main steps of the protocol proposed in this paper is concerned with the assessment of the Radon exhalation rate in order to verify that microwave treatments do not increase the Radon naturally exhalated by building materials. In this paper, the preliminary results of the Radon measurements performed on two different type of tuff samples (grey tuff and yellow tuff), typical of the Italian traditional construction heritage, with the E-PERM passive technique at the Environmental Radioactivity Laboratory (Amb.Ra.), University of Salerno, Italy, ISO 9001:2008 certified, are summarized.

Measurement of radon exhalation rate in various building materials and soil samples

Indoor radon is considered as one of the potential dangerous radioactive elements. Common building materials and soil are the major source of this radon gas in the indoor environment. In the present study, the measurement of radon exhalation rate in the soil and building material samples of Una and Hamirpur districts of Himachal Pradesh has been done with solid state alpha track detectors, LR-115 type-II plastic track detectors. The radon exhalation rate for the soil samples varies from 39.1 to 91.2 mBq kg−1 h−1 with a mean value 59.7 mBq kg−1 h−1. Also the radium concentration of the studied area is found and it varies from 30.6 to 51.9 Bq kg−1 with a mean value 41.6 Bq kg−1. The exhalation rate for the building material samples varies from 40.72 (sandstone) to 81.40 mBq kg−1 h−1 (granite) with a mean value of 59.94 mBq kg−1 h−1.

Measurements of radon exhalation rate in NORM used as consumer products in Japan

Twenty-five beauty products known to contain natural radionuclides were collected, and their 222Rn mass exhalation rates were measured. The effective doses to workers due to 222Rn exhaled from these products were estimated. The 222Rn mass exhalation rates of these products were below 177 μBq kg−1 s−1 and were almost identical to those of natural rocks in Japan. The maximum effective dose of 222Rn exhaled from these products was 71 μSv y−1.

Open charcoal chamber method for mass measurements of radon exhalation rate from soil surface

Radon exhalation rate from the soil surface can serve as an important criterion in the evaluation of radon hazard of the land. Recently published international standard ISO 11665-7 (2012) is based on the accumulation of radon gas in a closed container. At the same time since 1998 in Russia, as a part of engineering and environmental studies for the construction, radon flux measurements are made using an open charcoal chamber for a sampling duration of 3–5 h. This method has a well-defined metrological justification and was tested in both favorable and unfavorable conditions. The article describes the characteristics of the method, as well as the means of sampling and measurement of the activity of radon absorbed. The results of the metrological study suggest that regardless of the sampling conditions (weather, the mechanism and rate of radon transport in the soil, soil properties and conditions), uncertainty of method does not exceed 20%, while the combined standard uncertainty of radon exhalation rate measured from the soil surface does not exceed 30%. The results of the daily measurements of radon exhalation rate from the soil surface at the experimental site during one year are reported.

Study of radium and radon exhalation rate in soil samples from areas of northern Rajasthan

The health hazards of the radioactive gas radon on the humans are well known. Radon from soil gas is the main cause of radon problems. The “can technique” using LR-115 type II plastic track detectors have been used for the measurement of radon exhalation rate in soil samples from areas of northern Rajasthan, India. The radon exhalation values were calculated in terms of mass (EM) and area (EA). The mass exhalation rate in these samples vary from 8.27 to 23.19 mBq kg−1 h−1 with an average of 14.96 mBq kg−1 h−1, whereas, surface exhalation rate vary from 273.80 to 768.04 mBq m−2 h−1 with an average of 495.32 mBq m−2 h−1. The radium concentration ranges from 6.88 to 19.31 Bq kg−1 with an average value of 12.45 Bq kg−1. The observed values of effective radium concentration in all the soil samples are less than the permissible value of 370 Bq kg−1 as recommended by Organization for Economic Cooperation and Development (OECD). Hence, the result shows that this area is safe as for as the health hazard effects of radium and radon exhalation rate are concerned.