Absorbed Dose Rate In Air Research Articles

Radiological significance of coal, slag and fly ash samples from the Eastern Black Sea region

Abstract This work presents a study of natural radioactivity levels in coal and its combustion residues (fly ash and slag) used in the houses in Black Sea Region, Turkey. Coal, fly ash and slag samples were provided from different locations of the region and analyzed by gamma spectroscopy using a high-purity germanium detector (HPGe). Also, chemical analyses of these samples were carried out using energy dispersive x-ray fluorescence spectrometer. The mean 226Ra activity concentrations in coal, slag and fly ash were measured as 83, 99 and 38Bqkg–1, respectively. The mean 232Th activity concentrations in coal, slag and fly ash were measured as 108, 113 and 50Bqkg–1, respectively. The mean 40K activity concentrations in coal, slag and fly ash were found to be 366, 381 and 204Bqkg–1, respectively. The potential radiological hazards associated to these materials were evaluated by calculating the radium equivalent activity (Raeq), the air absorbed gamma dose rate (D), the annual effective dose rate (AED), the external hazard index (Hex) and internal hazard index (Hin) and compared with the internationally accepted or reference values. The mean Raeq values of the coal, fly ash and slag samples were lower than the recommended maximum values 370Bqkg–1 by the Organization for Economic Cooperation and Development (OECD). The overall mean outdoor terrestrial gamma air absorbed dose rate in coal, fly ash and slag samples are 119, 129 and 62nGyh–1 and the corresponding outdoor annual effective doses are 0.60, 0.32 and 0.64mSvy–1, which is higher than the worldwide average (0.07mSvy–1), respectively. Moreover, the enrichment factors relative to the input coal are calculated for the radionuclide contents observed. Calculated enrichment factor values for 226Ra and 232Th were found 1.14 and 1.01, respectively.

Environmental assessment of heavy metal and natural radioactivity in soil around a coal-fired power plant in China

Concentrations of heavy metals and natural radionuclides in soil around a major coal-fired power plant of Xi’an, China were determined by using XRF and gamma ray spectrometry, respectively. The measured results of heavy metals show that the mean concentrations of Cu, Pb, Zn, Co and Cr in the studied soil samples are higher than their corresponding background values in Shaanxi soil, while the mean concentrations of Mn, Ni and V are close to the corresponding background values. The calculated results of pollution load index of heavy metals indicate that the studied soils presented heavy metal contamination. The concentrations of 226Ra, 232Th and 40K in the studied soil samples range from 27.6 to 48.8, 44.4 to 61.4 and 640.2 to 992.2 Bq kg−1 with an average of 36.1, 51.1 and 733.9 Bq kg−1, respectively, which are slightly higher than the average of Shaanxi soil. The air absorbed dose rate and the annual effective dose equivalent received by the local residents due to the natural radionuclides in soil are slightly higher than the mean values of Shaanxi. Coal combustion for energy production has affected the natural radioactivity level and heavy metals (Cu, Pb, Zn, Co and Cr) concentrations of soil around the coal-fired power plant.

Radioactivity level of soil around Baqiao coal-fired power plant in China

Natural radioactivity level of soil around Baqiao coal-fired power plant in China was determined using gamma ray spectrometry. The concentrations of 226Ra, 232Th and 40K in the studied soil samples range from 27.6 to 48.8, 44.4 to 61.4 and 640.2 to 992.2Bqkg−1 with an average of 36.1, 51.1 and 733.9Bqkg−1, respectively, which are slightly higher than the average values of Shaanxi soil. The radium equivalent activity, the air absorbed dose rate and the annual effective dose rate were calculated and compared with the internationally reported or reference values. The radium equivalent activities of the studied samples are below the internationally accepted values. The air absorbed dose rate and the annual effective dose rate received by the local residents due to the natural radionuclides in soil are slightly higher than the mean value of Xi'an and worldwide.

Soil radioactivity levels and radiological risk assessment in the highlands of Hunza, Pakistan

This paper deals with the determination of (226)Ra, (232)Th, (40)K and (137)Cs in 42 soil samples collected from eight towns of Hunza district, at an average altitude of 2267 m, using gamma-ray spectrometry. The activity concentration data were analysed for frequency distribution and other descriptive measures. Risk assessment was done by calculating the hazard indices, air absorbed dose rate and external annual effective dose rate due to cosmic radiations, terrestrial radionuclides and (137)Cs deposited on the surface of the earth. Both indoor and outdoor occupancy factors were taken into account. The average dose rate due to cosmic radiation was estimated as 828 ± 87 µSv y(-1), from external terrestrial radiation as 97 ± 20 µSv y(-1) and from (137)Cs as 1.05 µSv y(-1) for a total annual effective dose rate of 926 ± 92 µSv. The results of the present study were discussed and compared with other similar studies performed in East Asia. The present study indicates that Hunza can be ranked among those areas having a high level of dose rate not only from cosmic rays but also from terrestrial radionuclides. This paper also proposes another measure of radiation hazard called 'radium equivalent for internal exposure'.

Results of environmental radiation monitoring at the Nuclear Fuel Cycle Engineering Laboratories, JAEA, following the Fukushima Daiichi Nuclear Power Plant accident

In response to the accident at the Fukushima Daiichi Nuclear Power Plant, emergency monitoring of the environmental radiation was performed at the Nuclear Fuel Cycle Engineering Laboratories (NCL), Japan Atomic Energy Agency (JAEA). This article describes the results of the monitoring, including air absorbed dose rate and radionuclide concentration in air and fallout. The air absorbed dose rate began to increase from about 1 am on 15 March 2011 and varied over time, with three peaks: 4.8 μGy/h, 2.1 μGy/h and 3.1 μGy/h at 8 am on 15 March, 5 am on 16 March and 4 am on 21 March, respectively. The increase in the radionuclide concentrations in air and fallout showed a tendency similar to that in the case of the dose rate. The 131I/137Cs concentration ratio in air varied considerably every day, and the maximum was about 100. The 137Cs amount in the fallout for a month from 15 March to April 15 was about 120 times higher than that after the Chernobyl accident in May 1986 and about 30 times higher than that in Tokyo in June 1963 during the atmospheric nuclear weapon tests. The committed effective dose due to inhalation was estimated from the observed radionuclide concentration in air.

Mapping the terrestrial air-absorbed gamma dose rate based on the data of airborne gamma-ray spectrometry in southern cities of China

An environmental radioactivity survey by Airborne Gamma-ray Spectrometry (AGS) on a large scale was undertaken in Zhuhai Zone (ZZ) and Shenzhen Zone (SZ), which include major cities in southern China, covering areas of 3800 km2 and 4660 km2, respectively. The estimated dose rates by AGS have been compared with observed results by ionization chamber and portable dosemeter. Maps of the terrestrial dose rate at 1m above ground level have been calculated based on the data of AGS. The mean dose rates are 84.37 ± 51.69 and 82.10 ± 32.98 nGy/h in ZZ and SZ, and the maximum rates are 343.11 and 368.36 nGy/h, respectively. Dose rates in some places are above 180 nGy/h; the areas covered where 149 km2 in ZZ and 43 km2 in SZ. The dominant geological conditions that evidently contribute to the radioactive anomalies are outcrops of Middle and Late Jurassic and Cretaceous biotitic-granite. The growth of industrialization and urbanization has dramatically altered radiation background. Stone mining results in the increase of radiation levels with maximum dose rates approaching 368.36 nGy/h in an open pit. The investigation results provide valuable background data and give a good example for mapping nationwide natural radiation terrestrial dose rates in China by AGS.

Natural radioactivity levels (K, Th and Ra) in some areas of Punjab, India

Radioactivity, natural and man-made, is omnipresent in the earth's crust in different amounts. Natural radioactive materials under certain conditions can reach hazardous radiological levels. So, it becomes necessary to study the natural radioactivity levels in soil to assess the dose for the population in order to know the health risks and to have a baseline for future changes in the environmental radioactivity due to human activities. 226Ra, 232Th and 40K analysis has been carried out in soil samples collected from some areas of Punjab, India using gamma-ray spectrometry. Phe technique of gamma ray spectrometry was applied using high purity germanium gamma-ray detector and a PC based MCA. Radium equivalent activities are calculated for the analyzed samples to assess radiation hazards arising due to the use of these soil samples in construction of dwellings. Phe measured activity in the soil ranges from 23.17 to 57.87 Bq kg−1, 59.03 to 160.40 Bq kg−1 and 228.06 to 501.03 Bq kg−1 for 226Ra, 232Ph and 40K with mean values of 37.93, 84.47 and 351.17Bqkg−1 respectively. It has been observed that on the average the outdoor terrestrial gamma air absorbed dose rate is about 84.65nGyh−1.

Radiological hazards of coal and ash samples collected from Xi’an coal-fired power plants of China

The natural radiological characteristics and their respective annual effective dose (AED) rates, produced by 226Ra, 232Th and 40K in coal, fly ash and bottom ash from two large coal-fired power plants (CFPPs) of Xi’an were determined by means of γ-ray spectrometry. The average activity concentrations of 226Ra, 232Th and 40K in all ash samples (fly ash and bottom ash samples) from the two CFPPs were 67.6, 74.3 and 225.3 Bq kg−1, respectively. The results are compared with data from other locations. To evaluate the radiological hazards of the natural radioactivity, the radium equivalent activity (Raeq), air absorbed dose rate (D), AED and external hazard index (H ex) are compared with internationally accepted values. Raeq and H ex of all samples except three fly ash samples were less than the limits of 370 Bq kg−1 and unity, respectively. The average D and AED for ash samples were 86.8 nGy h−1 and 0.11 mSv y−1, respectively, which exceed the world average and Xi’an average values.

Natural radioactivity levels in topsoil from the Pearl River Delta Zone, Guangdong, China

Concentrations of the natural radionuclides 238U, 226Ra, 232Th and 40K have been measured by γ-ray spectrometry in 796 topsoil samples from the Pearl River Delta Zone (PRDZ) of Guangdong, China. The mean concentrations for 238U, 226Ra, 232Th and 40K were found to be 140 ± 37 Bq kg −1, 134 ± 41 Bq kg −1, 187 ± 80 Bq kg −1 and 680 ± 203 Bq kg −1 dry mass, respectively. These values were all higher than the mean values in soil for China and the world. Outdoor air-absorbed dose rates, calculated from activity concentrations of 226Ra, 232Th and 40K, ranged from 86 to 237 nGy h −1, with a mean value of 165 ± 46 nGy h −1. The corresponding annual outdoor effective dose rate per person was estimated to be between 0.11 and 0.29 mSv y −1, with a mean value of 0.20 ± 0.06 mSv y −1, which was also higher than the world mean value of 0.07 mSv y −1. The radium equivalent activity (Ra eq) and the external hazard index ( I r) resulted from the natural radionuclides in soil, were also calculated and found to vary from 230 to 676 Bq kg −1 and from 0.6 to 1.8, respectively. The Ra eq and the I r in all the investigated regions were up to 75% higher than the set limits of 370 Bq kg −1 and 1.0, respectively.

Radioactivity in building materials in Iraq

Activity concentrations of (226)Ra, (232)Th and (40)K in 45 samples of different building materials used in Iraq were measured using gamma-spectroscopy system based on high-purity germanium detector with an efficiency of 40 %. Radium equivalent activity, air-absorbed dose rate, annual effective dose, external and internal hazard indices and alpha index due to radon inhalation originating from building materials were measured to assess the potential radiological hazard associated with these building materials. The activity concentrations of the natural radionuclides (226)Ra, (232)Th and 40K were found to range from below detection limit (BDL) to 223.7 ± 9, BDL to 93.0 ± 3 and BDL to 343.1 ± 12, respectively. Values of average radium equivalent activity, air-absorbed dose rate, indoor and outdoor annual effective doses, external and internal hazard indices and alpha index ranged from 6.5 to 124.9, 16.2 to 89.5 (nGy h(-1)), 0.08 to 0.44 mSv, 0.02-0.11 mSv, 0.09 to 0.53, 0.13 to 0.69 and 0.03 to 0.62, respectively. These values indicate a low dose. Therefore, the building materials used in the current study are quite safe to be used as building materials.

Determination of specific activity of 226Ra, 232Th and 40K for assessment of environmental hazards

Studies have been carried out using gamma-spectrometric techniques to determine the natural radioactivity in some rocks that are used as building materials in Yemen. The concentrations of the natural radionuclides namely(226) Ra, (232)Th and (40)K in the rock samples collected from different rock markets in Yemen have been determined using an NaI(Tl) detector. The concentrations of (226)Ra, (232)Th and (40)K in the studied rock samples range from 22.2 to 88.8 Bq kg(-1), 8.12 to 113.68 Bq kg(-1) and 31.3 to 2222.3 Bq kg(-1), respectively. The concentrations of these radionuclides are compared with the typical world values. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, the representative level index and the values of both external and internal hazard indices were evaluated and compared with the internationally approved values. The radium equivalent activity values of all rock samples are lower than the limit of 370 Bq kg(-1) except for one sample which is about 413.386. The values of external hazard index (H(ex)) and internal hazard index (H(in)), absorbed doses in indoor air and the corresponding effective dose equivalents in a typical dwelling are presented. The need for further studies is also discussed.

Measurement of natural radioactivity and assessment of associated radiation hazards in soil around Baoji second coal-fired thermal power plant, China

Activity concentrations of natural radionuclides (226)Ra, (232)Th and (40)K in soil around Baoji Second coal-fired thermal power plant of China were determined using gamma ray spectrometry. The mean activity concentrations of (226)Ra, (232)Th and (40)K in soil were found to be 40.3 ± 3.5, 59.6 ± 3.1 and 751.2 ± 12.4 Bq kg(-1), respectively, which are all higher than the corresponding average values in Shaanxi, Chinese and world soil. The radium equivalent activity (Ra(eq)), the air absorbed dose rate (D), the annual effective dose (E), the external hazard index (H(ex)) and internal hazard index (H(in)) were evaluated and compared with the internationally reported or reference values. All the soil samples have Ra(eq) lower than the limit of 370 Bq kg(-1) and H(ex) and H(in) less than unity. The overall mean outdoor terrestrial gamma air absorbed dose rate is ∼86.6 ± 3.4 nGy h(-1) and the corresponding outdoor annual effective dose is 0.106 ± 0.004 mSv, which is higher than the worldwide average (0.07 mSv y(-1)) for outdoor's annual effective dose.

Terrestrial Gamma Ray Dose Rates in Granitic Rock Terrains in Japan

Air absorbed dose rates evaluated from uranium, thorium and potassium contents in rock samples (rock dose rate) have been compared with K2O data in order to understand lithologic characteristics of terrestrial γ-ray dose rate levels in granitic rock terrains. The comparison showed that the dose rate increased with increasing K2O content of rock. The crystallization differentiation model of magma was used to analyze this trend quantitatively. Next, data sets were compiled with respect to dose rate measured on soil (soil dose rate) and K2O content of bedrock at the corresponding site. A semi-empirical formula expressing the soil dose rate as a function of K2O content of rock was derived by comparing with the rock dose rate analysis.

DETERMINATION OF THE NATURAL AND ANTHROPOGENIC RADIOACTIVITY IN THE SOIL OF GILGIT—A TOWN IN THE FOOTHILLS OF HINDUKUSH RANGE

The activity concentration of terrestrial (226Ra, 232Th, and 40K) and anthropogenic gamma-emitting radionuclide (137Cs) have been analyzed in 48 soil samples collected from Gilgit, a famous city for mountaineers and tourists in northern Pakistan, at an average altitude of 1,550 m, using gamma-ray spectrometry. The data analysis includes descriptive statistics, radium equivalent activity and its principal component analysis, air absorbed dose rate, annual effective dose rate, and collective effective dose equivalent. It is found that the level of cosmic exposure is high in Gilgit relative to the world average values, but the average outdoor annual effective dose rate from terrestrial radionuclides is lower as compared to its value in the soil of Punjab, Pakistan, and the world average values found in United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) for the general public. The median annual effective dose rate produced by 137Cs was 0.11 microSv y-1.

Terrestrial Gamma Ray Dose Rates in Dacitic and Rhyolitic Terrains

Air absorbed dose rate data taken at 36 sites have been analyzed in order to understand lithologic characteristics of dose rate levels measured on soils in dacitic and rhyolitic terrains. The dose rate increased with increasing K2O content of rock. The following three models were tested to interpret this trend, i.e., crystallization-differentiation of mafic or felsic magma, partial melting of mafic or felsic material, and mixing of mafic and felsic magmas. Semi-empirical formulas expressing the dose rate as a function of K2O content were derived based on the above models.

Environmental gamma radiation measurement in District Swat, Pakistan

External exposure to environmental gamma ray sources is an important component of exposure to the public. A survey was carried out to determine activity concentration levels and associated doses from (226)Ra, (232)Th, (40)K and (137)Cs by means of high-resolution gamma ray spectrometry in the Swat district, famous for tourism. The mean concentrations for (226)Ra, (232)Th and (40)K were found to be 50.4 +/- 0.7, 34.8 +/- 0.7 and 434.5 +/- 7.4 Bq kg(-1), respectively, in soil samples, which are slightly more than the world average values. However, (137)Cs was only found in the soil sample of Barikot with an activity concentration of 34 +/- 1.2 Bq kg(-1). Only (40)K was determined in vegetation samples with an average activity of 172.2 +/- 1.7 Bq kg(-1), whereas in water samples, all radionuclides were found below lower limits of detection. The radium equivalent activity in all soil samples is lower than the limit set in the Organisation for Economic Cooperation and Development report (370 Bq kg(-1)). The value of the external exposure dose has been determined from the content of these radionuclides in soil. The average terrestrial gamma air absorbed dose rate was observed to be 62.4 nGy h(-1), which yields an annual effective dose of 0.08 mSv. The average value of the annual effective dose lies close to the global range of outdoor radiation exposure given in United Nations Scientific Committee on the Effects of Atomic Radiation. However, the main component of the radiation dose to the population residing in the study area arises from cosmic ray due to high altitude.

Measurement of natural radioactivity in beach sands from Rizhao bathing beach, China

The natural radioactivity of (226)Ra, (232)Th and (40)K was determined for beach sand samples collected from Rizhao bathing beach, China, using gamma ray spectrometry. The measured activity in beach sand ranges from 7.6 to 17.2, 7.8 to 25.1 and 883.4 to 1313.6 Bq kg(-1) for (226)Ra, (232)Th and (40)K with mean values of 12.0, 15.2 and 1079.2 Bq kg(-1), respectively. The activity concentrations of (226)Ra and (232)Th in beach sands are lower, while (40)K is higher than the world average. The radium equivalent activity in all beach sand samples is lower than the safe limit set in the OECD report (370 Bq kg(-1)). The values of the external hazard index are less than unity. The mean outdoor air absorbed dose rate is 59.8 nGy h(-1) and the corresponding outdoor effective dose rate is 0.073 mSv y(-1).

226Ra, 232Th and 40K activities in soils of Cuihua Mountain National Geological Park, China

Gamma activity from the naturally occurring radionuclides namely, 226Ra, 232Th, the primordial radionuclide 40K was measured in the soil of Cuihua Mountain National Geological Park, China using γ-ray spectrometry technique. The mean activity of 226Ra, 232Th and 40K were found to be 27.2 ± 6.5, 43.9 ± 6.2 and 653.1 ± 127.6 Bq kg−1, respectively. The concentrations of these radionuclides were compared with the typical world values and the average activities of Chinese soil. The radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, and the external hazard index were evaluated and compared with the internationally approved values. All the soil samples have Raeq lower than the limit of 370 Bq kg−1 and Hex less than unity. The overall mean outdoor terrestrial gamma dose rate is 66.3 nGy h−1 and the corresponding outdoor annual effective dose is 0.081 mSv.

Terrestrial Gamma Ray Dose Rates in Andesitic Terrains

Air absorbed dose rate data taken at 31 sites have been analyzed in order to understand the characteristics of dose rate levels in andesitic terrains. The dose rate increased with increasing K2O content of rock. The following three models were tested to interpret this trend, i.e., crystallization-differentiation of basaltic magma, mixing of basaltic and felsic magmas and partial melting of mantle materials. A semi-empirical formula expressing the dose rate as a function of K2O content was derived based on the above models.

Radiological Characterization around the Afsin-Elbistan Coal-Fired Power Plant in Turkey

A radiological characterization of soil samples around the Afsin-Elbistan coal-fired thermal power plant in the Mediterranean region of Turkey was carried out. Moreover, activity concentrations and chemical analyses of coal samples used in this power plant and fly ash and slag samples originating from coal combustion were measured. For this purpose, coal, fly ash, slag, and soil samples were collected from this region. The analysis shows that the samples include relevant natural radionuclides such as 226Ra, 232Th and 40K. The mean activity concentrations of 226Ra, 232Th, and 40K were 167, 44, and 404 Bq·kg−1, respectively. Obtained values shows that the average radium equivalent activity, air-absorbed dose rate, annual effective dose, and external hazard index for all samples are 258 Bq·kg−1, 121 nGy·h−1, 148 μSv·y−1, and 0.7, respectively. The environmental effect of natural radionuclides caused by coal-fired power plants was considered to be negligible because the Raeq values of the measured samples are...