Determination Of Radon Exhalation Rate Research Articles

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

Determination of radon exhalation rate from different mixture of concrete

Determination of radon exhalation rate from different mixture of concrete

Radiological implications of using phosphogypsum as building material: a case study of Brazil

Phosphogypsum, a waste byproduct derived from the production of phosphoric acid, is being worldwide stockpiled, posing concerns about the environmental problems originating from this practice. Considerations about the viability of the safe reuse of this material have been raised, among them its potential use as building material. However, as phosphogypsum can contain natural radionuclides in significant concentrations, using it as a building material has radiological implications, which presently prevent such application. In order to evaluate the feasibility of using phosphogypsum in the manufacturing of building elements such as bricks and plates, a comprehensive research was undertaken in Brazil, following a multiple approach. This research included studies related to: Brazilian phosphogypsum characterization; experimental determination of radon exhalation rate; and application of theoretical models to forecast both radon exhalation and external doses in dwellers. In this paper, a comprehensive review of the research carried out in Brazil is presented.

A Study of Greek Building Materials as Indoor Radon Sources

A survey of radon emanation in building materials commonly used in Attica has initiated at our laboratory as part of a broader EU program. The objective is to obtain a characterisation of the Greek building materials as indoor radon sources and identify the cases where some specific countermeasures should be applied. Up to now, bricks commonly used in Attica have been studied for both radium content and radon emanation. Gamma-ray spectroscopy techniques, as well as radon exhalation measurements, have been employed. For determination of radon exhalation rate, besides the trivial method which consist of a single measurement of radon concentration in a closed vessel containing the sample, a short-time continuous accumulation/counting method has been established. The results of exhalation measurements have been used together with high-resolution gamma-spectrometry in order to determine radon emanation coefficients.

Determination of radon exhalation rates from soil around buildings in Lagos environments using passive measurement technique.

In this study, measurements of radon concentrations and estimation of exhalation rates were carried out in soil around buildings within Lagos State in order to determine the contribution to indoor radon concentrations from the soil, and determine the influence of soil moisture on the exhalation rates. Fifty-four samples were collected randomly with 27 measured as wet samples and 27 dried before measurements so as to account for the moisture content. Passive measurement method, using cover cup technique with solid state nuclear track detectors, CR-39, was employed. The results showed weak correlations between the concentrations of radon emanated from the soil samples and the indoor radon concentrations. The results obtained suggested lower concentrations of radon emanated from wet soil than dry soil indicating the influence of moisture. The results further indicate that the highest and lowest values as well as the highest mean for both wet and dry soil samples were obtained from the same environment, suggesting that the soil in that environment are of anomalous petrophysical property. Concentrations of radon emanated from dry soil are higher than in wet soil, suggesting that the presence of moisture may results in reduction of radon concentrations in soil samples. The result of the surface exhalation rates and the mass exhalation rates are in congruent with results obtained for the concentrations of radon emanated from wet and dry soil samples.

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.

Determination of radon exhalation rates in soil samples using sealed can technique and CR-39 detectors.

BackgroundIn this study, the so-called sealed can technique dosimeters have been used to determine the radon exhalation rates in soil samples collected from different sites in Bethlehem region- Palestine.MethodsFor the measurement of radon concentration emanated from these samples, alpha-sensitive, Solid State Nuclear Track Detectors (SSNTD’s) have been used. A total of 82 soil samples were collected simultaneously.ResultsIt was found that the radon concentrations in these soil samples varied from 19.1 Bqm−3 to 572.9 Bqm−3 with an average value of 145.0 Bqm−3. The radon exhalation rate in these collected samples also varied from 6.9 mBqm−2 h−1 (0.26 mBqkg−1 h−1) to 207.2 mBqm−2 h−1 (7.84 mBqkg−1 h−1) with an a total average value of 52.2 mBqm−2 h−1 (1.97 mBqkg−1 h−1).ConclusionsAll the values of radium content in all samples under test were found to be quite lower than the corresponding the global value 30 Bqkg−1. The present results show that the radon concentration and the resulting doses in all soil samples are below the allowed limit from ICRP. The radiological health implication to the population that may result from these doses is found to be low. The measurements have been taken as representing a baseline database of values of these radionuclides in the soils in the area. The results were compared with national and worldwide results.

Determination of Radon Exhalation Rates and Emanation Factor of Some Soil Samples Collected From Southern Seashore of Kerala, India

Determination of Radon Exhalation Rates and Emanation Factor of Some Soil Samples Collected From Southern Seashore of Kerala, India

USE OF COMMERCIAL RADON MONITORS FOR LOW LEVEL RADON MEASUREMENTS IN DYNAMICALLY OPERATED VOC EMISSION TEST CHAMBERS.

Compared to the intended EU reference level of 300 Bq m-3 for indoor radon concentrations, the contribution of building materials appears to be low. Considering the recommended limit of 100 Bq m-3 by WHO, their contribution is supposed to be relevant, especially at low air exchange rates. This study as part of a two-part research project investigated the suitability of direct low level 222Rn measurement under simulated indoor conditions with commercial radon monitors and dynamically operated emission test chambers. Active measuring devices based on ionisation or scintillation chambers with 1-σ uncertainties below 8.6% at 20 Bq m-3 were found to be best suitable for a practical test procedure for the determination of radon exhalation rates of building materials. For the measurement of such low concentrations, the knowledge of the accurate device background level is essential.

Determination of radon exhalation rate and natural radioactivity levels of building materials used in Istanbul-Turkey

Radon concentrations of 63 building materials (block-form and powder-form) used in Istanbul province were measured by using solid state nuclear track detectors (CR-39). Radon exhalation rates for each other were calculated and compared to the literature. The activity concentrations of 40K, 238U and 232Th for 18 powder-form building materials (cement and sand samples) were analyzed by a gamma-ray spectrometer coupled with a NaI(Tl) detector. The activity concentrations of 40K, 238U and 232Th ranged from 2.81 to 638.9 Bqkg−1, 44.68 to 114.26 Bqkg−1 and 2.02 to 34.16 Bqkg−1, respectively. Activity of 238U in sand samples was found as higher than the world average. The activities of 40K, 238U and 232Th are compared with available data from other investigations and the world average value. Radiation hazard indices (radium equivalent activity, external hazard index and indoor hazard index) were calculated by using the activity results. The results are compared to the literature.

Measurements of natural radioactivity and radon exhalation rates from different brands of cement used in Pakistan

The measurement of activity due to the naturally occurring radionuclide has been carried out in different brands of cement available in Pakistan. The gamma spectra of the collected samples were obtained using high-purity germanium detector and analysed for the presence of 232Th, 238U and 40K. The assessment of radiological hazards due to these radionuclides has also been made. The studies concerning the determination of radon-exhalation rates from these samples of cement were also carried out using CR-39 based NRPB radon dosimeters. The range of activity concentrations were found for 226Ra (from 25.10 +/- 1.55 to 52.60 +/- 3.20 Bq kg(-1)), 232Th (from 10.30 +/- 0.65 to 30.40 +/- 1.70 Bq kg(-1)) and 40K (from 17.25 +/- 1.55 to 292.95 +/- 23.05 Bq kg(-1)). The estimated value of radium equivalent concentration was from 11.16 +/- 2.60 to 114.98 +/- 7.11 Bq kg(-1). The calculated absorbed dose rate in air and the annual effective dose were in the range from 18.54 +/- 1.17 to 52.90 +/- 3.31 nGy h(-1) and 0.09 +/- 0.01 to 0.26 +/- 0.02 mSv, respectively. The external and internal hazard indices were in the range from 0.11 +/- 0.01 to 0.31 +/- 0.02 and 0.18 +/- 0.01 to 0.45 +/- 0.03, respectively. The radon exhalation rates from different brands of cement were found in the range from 3.3 +/- 0.7 to 8.1 +/- 1.7 mBq kg(-1) h(-1).

Studying 222Rn exhalation rate from soil and sand samples using CR-39 detector

Accurate knowledge of exhalation rate plays an important role in characterization of the radon source strength in building materials and soil. It is a useful quantity to compare the relative importance of different materials and soil types. Majority of houses in Pakistan are mainly constructed from soil and sand. Therefore, studies concerning the determination of radon exhalation rate from these materials were carried out using CR-39 based NRPB radon dosimeters. In this context, samples were collected from different towns of the Bahawalpur Division, Punjab and major cities of NWFP. After treatment, samples were placed in plastic containers and dosimeters were installed in it at heights of 25 cm above the surface of the samples. These containers were hermetically sealed and stored for three weeks to attain equilibrium between 222Rn and 226Ra. After exposure to radon, CR-39 detectors were etched in 25% NaOH at 80 °C for 16 h. From the measured radon concentration values, 222Rn exhalation rates were determined. It ranged from 1.56 to 3.33 Bq m - 2 h - 1 for the soil collected from the Bahawalpur Division and 2.49– 4.66 Bq m - 2 h - 1 for NWFP. The 222 Rn exhalation rates from the sand samples were found to range from 2.78 to 20.8 Bq m - 2 h - 1 for the Bahawalpur Division and from 0.99 to 4.2 Bq m - 2 h - 1 for NWFP. 226Ra contents were also determined in the above samples which ranged from 28 to 36.5 Bq kg - 1 in the soil samples collected from the Bahawalpur Division and from 40.9 to 51.9 Bq kg - 1 in the samples collected from NWFP. In sand samples, 226Ra contents ranged from 49.2 to 215 Bq kg - 1 and 22.6– 27 Bq kg - 1 in the samples collected from the Bahawalpur Division and NWFP, respectively. 226Ra contents in these samples were also determined using HPGe detector. The results of both the techniques are in good agreement within experimental errors.

Determination of radon exhalation rates from tiles using active and passive techniques

Measurements of radon exhalation rates for selected samples of tiles used in Saudi Arabia were carried out using active and passive measuring techniques. These samples were granite, marble and ceramic. In the active method, a PC-based radon gas analyzer with emanation container was used, while, in the passive method, PM-355 nuclear track detectors with the “can technique” were applied for 180 days. A comparison of the exhalation rates measured by the two techniques showed a good linear correlation coefficient of 0.7. The granite samples showed an average radon exhalation rate of 0.7 Bq m −2 h −1 , which was higher than that of marble and ceramic by more than twofold. The radon exhalation rates measured by the “can technique” showed a non-uniform exhalation from the surface of the same tile.

Study of natural radionuclides and radon emanation in bricks used in the Attica region, Greece

Bricks commonly used in the Attica region, Greece have been studied for both natural radionuclide content and radon emanation. The high-resolution γ-ray spectroscopy technique, as well as radon exhalation measurements, have been employed. For determination of radon exhalation rate, besides the trivial method which consists of a single measurement of radon concentration in a closed vessel containing the sample, a shorter duration continuous accumulation/counting method has been established. The results of radon exhalation measurements have been used together with the γ-spectrometry determination of 226Ra in order to determine radon emanation coefficients.

Natural Radioactivity and Radon Exhalation from Building Materials Used in Attica Region, Greece

In order to extend our study of natural radionuclides and radon exhalation from building materials used in Attica region, Greece, measurements on concrete have been performed. In a previous study the major types of bricks used in Attica have been studied and the results of that study are here quoted for comparison. All the results are compared with similar values presented by other authors and the radioactivity levels are discussed in terms of limits to the accepted natural radioactivity levels. The method used for the determination of radon exhalation rates from concrete is the continuous accumulation/counting method that has been previously established.

Determination of radon exhalation rates from Canadian building materials with an internal proportional counter

Radon exhalation rates of 11 typical Canadian building materials (55 different samples) range from very low (<0.1 nBq g −1 s −1 or <0.1 nBq cm −2 s −1 ) to moderate (19 nBq g −1 s −1 and 22 nBq cm −2 s −1 . Wood, glass, slate and marble have low exhalation rates (≈0.1 nBq g −1 s −1 ) while ceramic tiles, concrete, fiberglass, gravel and gypsum have mean rates which vary from 0.7 to 5.4 nBq g -1 s −1 and from 0.4 to 5.1 nBq cm −2 s −1 . Concrete is the strongest emanator among the materials studied.

The determination of radon exhalation rates.

The exhalation of radon from porous materials like mining wastes and building materials can be determined by studying the growth of radon activity in vessels containing samples of the materials. It is demonstrated that the initial part of the activity growth curve determines the total free exhalation rate of the sample used, independently of container leakage and back diffusion. It is furthermore shown that a specific area exhalation rate adequately describes the exhalation process, when the exhalation is restricted to take place in one direction only, and when the dimension in the exhaling direction is greater than approx. 2 times the diffusion length. A determination of the free surface exhalation rate as a function of the sample thickness also yields information on the diffusion length, as well as the radon production rate per unit volume of material. In case of sample dimensions smaller than about half the diffusion length, the total exhalation rate is shown to be proportional to the mass or volume of the sample.