Total Absorbed Gamma Dose Rate Research Articles

Distribution and impacts of contamination by natural and artificial radionuclides in attic dust and urban soil samples from a former industrial Hungarian city: A case study from Salgótarján

Primordial radionuclides can be found in all environmental compartments. Since coal-fired power plants (CFPP) can be a source of additional radionuclide contamination because coal contains natural radioactive isotopes such as 238U (226Ra) and 232Th. This study investigated the impact of such possible radionuclide contamination from former heavy industrial activities, namely a former local coal-fired power plant, in urban soils and attic dust in Salgótarján, Hungary. Even today, industrial by-products, e.g., coal ash, in this city represent significant threat to its residents. A total of 36 attic dust samples (family houses, kindergartens, churches and blockhouses) were collected and 19 urban soil samples (playgrounds, kindergartens, parks and others) were selected no further than 500 m from the corresponding attic dust sampling sites. Additionally, a coal ash and a brown forest soil sample were also collected to differentiate between the anthropogenic and geogenic sources in the residential area. The sampled houses, built between 1890 and 1990, are considered to be representative sampling sites for long-term accumulations of attic dust. The mean values of the total U, Th and Cs (mg kg−1) concentrations as well as those of K (m/m %) in attic dust and urban soil samples are 2.4, 3.6, 1.7 and 0.6 and 1.1, 4.4, 1.2 and 0.3, respectively, measured using ICP-MS. The mean activity concentrations of 226Ra, 232Th, 40K and 137Cs in attic dust and urban soil samples are 43.3, 34.0, 534.4 and 88.5 and 25.1, 32.8, 386.4 and 5.6 Bq kg−1, respectively, by using a low-background iron chamber with a well-type HPGe and a n-type coaxial HPGe detector.The elemental compositions (U, Th) and activity concentrations (226Ra, 232Th) along with their abundances in coal ash from the CFPP increase in both studied media as the distance of the sampling sites from the CFPP decreases. Two outlier attic dust samples in particular show significantly high activity concentrations of 226Ra: 145 and 143, of 232Th: 83 and 94 Bq kg−1, which can be considered as a proxy of unweathered coal ash. The calculated total absorbed gamma dose rate (D) and annual effective dose (E) received from urban soils indicate that the presence of the CFPP, coal ash cone and slag dumps does not cause an increase in the level of background radiation in Salgótarján. However, the concentrations of the studied radionuclides are much higher (except for 232Th) and exhibit higher degree of variability in the samples of attic dustthan in those of urban soils. The study suggests that attic dust preserves the undisturbed ‘fingerprints’ of long-term atmospheric deposition thanks to its chemical and physical properties unlike urban soil.

Natural radionuclides and assessment of radiological hazards in MuongHum, Lao Cai, Vietnam

226Ra, 238U, 4 K, and 232Th (228Ra) activity concentrations of 61 soil samples distributed surrounding the rare earth element mine (NORM), MH, Lao Cai, Vietnam have been measured by HPGe detector. The activity concentrations of 226Ra, 238U, 4 K, and 232Th (228Ra) range from 1179 to 6291 Bq/kg, from 1024 to 8351 Bq/kg, from 260 to 3519 Bq/kg, and from 1476 to 35546 Bq/kg in the ore body and from 21.3 to 964 Bq/kg, from 23.4 to 1635 Bq/kg, from 124 to 3788 Bq/kg, and from 40.9 to 6107 Bq/kg outside the ore body in respective. The study area is considered as the high local natural background radiation with the concentration of 226Ra, 238U, 4 K, and 232Th (228Ra) of 156, 254, 647, and 908 Bq/kg in respective. Regarding the spatial distribution, the measured radionuclide concentrations are independent of the distance from measured points to the ore body. With regard to the hazard indices, the average calculated radiological hazard indices, including absorbed gamma dose rate, effective dose equivalent, and excess lifetime cancer risk significantly exceed the global average values. There is a disequilibrium between 238U/226Ra concentrations in studied soil samples. The results also found that the 232Th (228Ra) concentration and total absorbed gamma dose rate show a strong positive correlation (coefficient of determination, R2 = 1).

Radioactivity and Risk Assessment with Uncertainty Treatment for Analysis of Black Sand Minerals

Precise radiological analysis of environmental, ores, nuclear materials and minerals samples is of great value for monitoring and surveillance objectives. The information deduced from the analysis can be used to identify the origin and nature of the accompanied activities. This work focuses on analysis of some black sand ore samples to identify and quantify their radioisotopes and potential risk. The analysis can provide useful information about the environmental transport mechanism and about the sources of radionuclides in the studied area; Rashid city coast, Egypt. To achieve this target, a Non‐destructive gamma spectrometer (NDGS) was used to trace and amount the radioisotopes types and activities. The efficiency was calculated with uncertainty treatment. The specific activity with uncertainty assessment of 238U, 232Th decay series and 40K of these samples were varied from 72.2 to 252.4 with average value 111 ± 25 Bq·kg–1, 94.2 to 579.8 with average value 140 ± 22 Bq·kg–1 and 427.9 to 527.5 with average value 475 ± 36 Bq·kg–1 respectively. The mineralogical signature of the analyzed samples (XRD) indicates that the samples are mainly composed of ilmenite, zircon, rutile, sphene and monazite. The potential risk assay shows that the hazard parameters of these samples; the Absorbed Gamma Dose Rate (AGDR), Gamma Activity Index (Iγ), Annual Effective Dose Rate Equivalent (AEDRE), Radium equivalent, External and Internal Hazard Index (Hex and Hin) are of specific characteristics. The total absorbed gamma dose rate and the annual effective dose due these samples were found to be with average values 158 ± 24 (nGy/h) and 195 ± 29 (μSv/y) which are higher than the world average value of 59 nGy/h and 70 μSv/y respectively. The results obtained are important to establish baseline levels to detect any upcoming changes due to any activities. It can be observed that the studied area has elevated thorium and uranium content. The relatively high dose rate will be considered as a spa for the physical therapy such as treatment of some skin diseases and rheumatoid.

Analysis of radioactivity levels and hazard assessment of black sand samples from Rashid area, Egypt

Abstract The aim of this study is to evaluate the radioactivity levels and radiological impacts of representative black sand samples collected from different locations in the Rashid area, Egypt. These samples were prepared and then analyzed using the high-resolution gamma ray spectroscopy technique with a high-purity germanium detector. The activity concentration ( A c ), minimum detectable activity, absorbed gamma dose rate, external hazard index ( H ex ), annual effective dose rate equivalent, radium equivalent, as well as external and internal hazard index ( H ex and H in , respectively) were estimated based on the measured radionuclide concentration of the 238 U( 226 Ra) and 232 Th decay chains and 40 K. The activity concentrations of the 238 U, 232 Th decay series and 40 K of these samples varied from 45.11 ± 3.1 Bq/kg to 252.38 ± 34.3 Bq/kg, from 64.65 ± 6.1 Bq/kg to 579.84 ± 53.1 Bq/kg, and from 403.36 ± 20.8 Bq/kg to 527.47 ± 23.1 Bq/kg, respectively. The activity concentration of 232 Th in Sample 1 has the highest value compared to the other samples; this value is also higher than the worldwide mean range as reported by UNSCEAR 2000. The total absorbed gamma dose rate and the annual effective dose for these samples were found to vary from 81.19 nGy/h to 497.81 nGy/h and from 99.86 μSv/y to 612.31 μSv/y, which are higher than the world average values of 59 nGy/h and 70 μSv/y, respectively. The H ex values were also calculated to be 3.02, 0.47, 0.63, 0.87, 0.87, 0.51 and 0.91. It was found that the calculated value of H ex for Sample 1 is significantly higher than the international acceptable limit of

Analysis of natural radionuclides in soil samples of Purola area of Garhwal Himalaya, India.

Naturally occurring radioactive materials are widely spread in the earth's environment, being distributed in soil, rocks, water, air, plants and even within the human body. All of these sources have contributed to an increase in the levels of environmental radioactivity and population radiation doses. This paper presents the activity level due to the presence of (226)Ra, (232)Th and (40)K in soil samples of Purola area in Garhwal Himalaya region. The measured activity of (226)Ra, (232)Th and (40)K in collected soil samples of Purola was found to vary from 13±10 to 55±10 Bq kg(-1) with an average of 31±2 Bq kg(-1), 13±10 to 101±13 Bq kg(-1) with an average 30±3 Bq kg(-1) and 150±81 to 1310±154 Bq kg(-1) with an average 583±30 Bq kg(-1), respectively. The radium equivalent activity in collected soil samples was found to vary from 47 to 221 Bq kg(-1) with an average of 115 Bq kg(-1). The total absorbed gamma dose rate in this area was found to vary from 22 to 93 nGy h(-1) with an average of 55 nGy h(-1). The distribution of these radionuclides in the soil of study area is discussed in details.

On the radiological assessment of natural and fallout radioactivity in a natural high background radiation area at Odisha, India

Natural and fallout radioactivity were estimated in surface soil samples collected around a natural high background radiation area (NHBRA) at Odisha, India using high resolution gamma ray spectrometry. Radiological characterization of the surface soil samples was done by the estimation of radiation hazard indices e.g. external absorbed gamma dose rate (D), radium equivalent activity (Raeq) and activity concentration index (I). The estimated total absorbed gamma dose rate ranged between 46.2 and 964.2 nGy/h with an average of 341.4 nGy/h, higher than the global average of 58 nGy/h but compared with the other reported NHBRA in India and worldwide.

Study of natural radionuclide and absorbed gamma dose in Ukhimath area of Garhwal Himalaya, India

Natural radiation is the largest contributor to the collective radiation dose of the world population. It is widely distributed in different geological formations such as soil, rocks, air and groundwater. In the present investigation, (226)Ra, (232)Th and (40)K were measured in soil samples of the Ukhimath region of Garhwal Himalaya, India using NaI(Tl) gamma-ray spectrometry. The activity concentrations of naturally occurring radionuclides (226)Ra, (232)Th and (40)K were found to vary from 38.4 ± 6.1 to 141.7 ± 11.9 Bq kg(-1) with an average of 80.5 Bq kg(-1), 57.0 ± 7.5 to 155.9 ± 12.4 Bq kg(-1) with an average of 118.9 Bq kg(-1) and 9.0 ± 3.0 to 672.8 ± 25.9 Bq kg(-1) with an average of 341 Bq kg(-1), respectively. The total absorbed gamma dose rate varies from 70.4 to 169.1 nGy h(-1) with an average of 123.4 nGy h(-1). This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details.

Studies of natural radionuclides and dose estimation from soil samples of Kumaun Himalaya, India

In the present study, the distribution of natural radionuclides in soil samples collected from different geological units of Kumaun Himalayas are assessed using gamma ray spectrometer with Nal(Tl) detector. The naturally occurring radioactivity concentration of 226Ra, 232Th and 40K were found to vary from 36.4 Bq/kg to 166.6 Bq/kg, 15.3 Bq/kg to 94.7 Bq/kg and 645.9 Bq/kg to 1378.9 Bq/kg, respectively. The total absorbed gamma dose rate was found to vary from 80 nGy/h to 179.6 nGy/h. The resulting dose due to the presence of these radionuclides was estimated from radiation protection point of view. The significance of this investigation is also discussed in details.

Characterization of phosphogypsum wastes associated with phosphoric acid and fertilizers production

The present work is directed to characterize the phosphogypsum (PG) wastes associated with phosphoric acid produced by the wet process in industrial facility for the production of fertilizers and chemicals in Egypt. The PG waste samples were characterized in terms of spectroscopic analysis (X-ray diffraction, X-ray fluorescence, IR spectra) and radiometric analysis (γ- and α-measurements). The γ-ray measurements showed that the average activity concentrations are 140 ± 12.6, 459 ± 36.7, 323 ± 28.4, 8.3 ± 0.76 and 64.3 ± 4.1 Bq/kg for U-238, Ra-226, Pb-210, Th-232 and K-40, respectively. The α-particle measurements of uranium isotopes showed that the average activity concentrations of U-238, U-235 and U-234 were 153 ± 9.8, 7 ± 0.38, 152 ± 10.4 Bq/kg, respectively. The average radiochemical recovery (%) of the destructive α-particle measurements is ∼70% with a resolution (FWHM) of ∼30 keV. Activity ratios of U-238/Ra-226 and U-238/Pb-210 were less than unity (i.e., <1) and equal to 0.31 ± 0.02 and 0.47 ± 0.16, respectively. The isotopic ratios of U-238/U-235 and U-238/U-234 (in PG and PR samples) were close to the normal values of ∼21.7 and ∼1, respectively and are not affected by the wet processing of phosphate rock (PR). The obtained results of PG waste samples were compared with phosphate rock (PR) samples. The radiation hazard indices are namely, radium activity index (Ra-Eq > 370 Bq/kg), total absorbed gamma dose rate ( D γr > 5 nGy/h) and radon emanation fraction (Rn-EF > 20%). Uncertainty of the sample counting was 95% confidence level of σ. The results indicated the necessity to find suitable routes to decrease and/or redistribute the radionuclide of environmental interest (i.e., Ra-226) in PG wastes, consequently to reduce its radiation impacts in the surrounding environment.

Radioactivity of sand from several renowned public beaches and assessment of the corresponding environmental risks

The radiological risk due to the presence of natural and man-made radionuclides in beach sands from several renowned seaside and riverbank public beaches was estimated in this study. The exposure levels to terrestrial radiation of the beaches were determined, as well as hazards due to human use of the analyzed sands in industry and in building constructions. Specific radionuclides concentrations in the sand samples were determined by standard gamma-spectrometry. The corresponding radiation hazards arising due to the use of sand as a building material were estimated by three different radiological hazard indices. The total absorbed gamma dose rate in the air was determined and the corresponding annual effective dose outdoors was estimated. The obtained data are relevant both from human health and environmental monitoring aspects.

Population doses from terrestrial gamma exposure in Serbia

Background: Terrestrial radiation emitted from naturally occurring radionuclides, such as 40K and radionuclides from the 238U and 232Th series and their decay products represent the main external source of irradiation to the human body. The purpose of this study was to provide a preliminary assessment of the doses from terrestrial exposure of population in Serbia and to estimate a potential radiation hazard for population inhabiting investigated areas. Methods: The gamma dose rates, external hazard indexes, and annual effective doses due to terrestrial naturally occurring radionuclides (238U, 232Th and 40K) were calculated based on their activities in soil samples in Serbia as determined by gamma-ray spectrometry. Results: The total absorbed gamma dose rate due to these radionuclides varied from 16.9 to 125 nGy h-1, with a mean of 62.8 nGy h-1. Assuming a 20% occupancy factor, the corresponding annual effective dose varied from 2.07 to 15.4?10-5 Sv with the mean value of 7.7?10-5 Sv, i.e. annual effective dose was in range of the world wide average values. Conclusion: According to the values of external hazard index obtained in this study (mean Hex = 0.35), the radiation hazard was insignificant for the population living in investigated areas.

Natural and anthropogenic radionuclides in rocks and beach sands from Ezine region (Çanakkale), Western Anatolia, Turkey

This paper represents the first reports on the natural and anthropogenic radionuclides in Kestanbol granitic pluton and surrounding rocks, and coastal region of the Ezine town. To assess the radiological hazard of the natural radioactivity, the radium equivalent activity, the absorbed dose rate and the external hazard index were calculated, and in situ gamma dose rates were measured. The high-activity concentrations were measured in the pluton and sands, which was originated mainly from the pluton, due to the presence of zircon, allanite, monazite, thorite, uranothorite and apatite. The average activity concentrations of 238U, 232Th and 40K are 174.78, 204.69 and 1171.95 Bq kg −1 for pluton, and 290.36, 532.04 and 1160.75 Bq kg −1 for sands, respectively. 137Cs in Ezine region ranged from 0–6.57 Bq kg −1. The average absorbed dose rate for the granitic and sand samples were calculated to be 251.6 and 527.92 nGy h −1, respectively. The maximum contribution to the total absorbed gamma dose rate in air was due to the 232Th (52.3% for pluton and 67.1% for sands). The Raeq activities of the pluton and sands are higher than the recommended maximum value of 370 Bq kg −1 criterion limit of Raeq activity for building materials.

Assessment of gamma dose rates from terrestrial exposure in Serbia and Montenegro

The gamma dose rates due to naturally occuring terrestrial radionuclides ((226)Ra, (232)Th and (40)K) were calculated based on their activities in soil samples, determined by gamma-ray spectrometry. A total of 140 soil samples from 21 different regions of Serbia and Montenegro were collected. The gamma dose rates ranged from 7.40 to 29.7 nGy h(-1) for (226)Ra, from 12.9 to 46.5 nGy h(-1) for (232)Th and from 12.5 to 37.1 nGy h(-1) for (40)K. The total absorbed gamma dose rate due to these radionuclides varied from 34.5 to 97.6 nGy h(-1) with mean of 66.8 nGy h(-1). Assuming a 20% occupancy factor, the corresponding annual effective dose varied from 4.23 x 10(-5) to 11.9 x 10(-5) Sv with mean of 8.19 x 10(-5) Sv, i.e. the dose was lower than world wide average value. According to the values of external hazard index (mean: 0.39) obtained in this study, the radiation hazard was found to be insignificant for population living in the investigated area.

Distribution of natural and anthropogenic radionuclides in soil and beach sand samples of Kalpakkam (India) using hyper pure germanium (HPGe) gamma ray spectrometry

Pre-operational survey at Kalpakkam coast, indicated elevated gamma background radiation levels in the range of 100–4000 nGy h −1 over the large tracts of the coastal sands due to the presence of pockets of monazite mineral in beach sands. In view of the prevalence of monazite, a systematic gamma spectrometric study of distribution of natural radionuclides in soil and beach sand samples collected from the terrestrial and coastal environment of Kalpakkam was performed and concentrations of primordial radionuclides such as 238U, 232Th and 40K and anthropogenic radionuclide 137Cs were determined. The concentrations of 238U, 232Th and 40K in soil samples were 5–71, 15–776 and 200–854 Bq kg −1 dry, respectively. In beach sand samples, 238U, 232Th and 40K contents varied in the range of 36–258, 352–3872 and 324–405 Bq kg −1 dry, respectively. The total absorbed gamma dose rate in air due to the presence of 238U, 232Th and 40K in Kalpakkam soil samples varied between 24 and 556 nGy h −1 with a mean of 103 nGy h −1. The contribution to the total absorbed gamma dose rate in air in the decreasing order was due to the presence of 232Th (76.4%), followed by 40K (16.9%) and 238U (6.7%) in Kalpakkam soils. However, in beach areas of Kalpakkam, the presence of 232Th in beach sand contributed maximum (94.0%) to the total absorbed gamma dose rate in air followed by 238U (4.7%) and minimum contribution was by 40K (1.3%). 137Cs in Kalpakkam soils ranged from ⩽1.0 to 2.8 Bq kg −1 dry, which was 1–3 order of magnitude less than the concentration of primordial radionuclides in soil.

Contribution of 137Cs to the total absorbed gamma dose rate in air in a Greek forest ecosystem: measurements and Monte Carlo computations.

The absorbed gamma dose rate in air 1 m above soil due to natural gamma emitters and 137Cs from the Chernobyl accident was determined inside a Quercus conferta Kit ecosystem in Northern Greece by combination of Monte Carlo simulations with the MCNP code and in-situ gamma spectrometry measurements. The total absorbed gamma dose rate in air is about 64 nGy h(-1), where 40% of this value is due to 137Cs and 60% to natural gamma emitters. The Monte Carlo simulations indicated that the gamma absorbed dose rate in air due to 137Cs is mainly due (70%) to unscattered radiation and to a lesser extent (30%) to the scattered radiation. The results obtained with the Monte Carlo simulations for the unscattered radiation were in very good agreement with the experimental values deduced by in-situ gamma spectrometry measurements. From the combination of the Monte Carlo simulations and in-situ gamma spectrometry measurements a conversion factor C = 1 nGy h(-1)/kBq m(-2) was deduced for 137Cs. This factor must be used with caution and only for forest sites similar to the one used for this work.

Technical alternatives for energy management : S. J. Freedman, Towne School of Civil and Mechanical Engineering, National Center for Energy Management and Power, University of Pennsylvania, Philadelphia, Pa. 19104. Energy Conversion13, 57–65 (1973)

The present work is directed to characterize the phosphogypsum (PG) wastes associated with phosphoric acid produced by the wet process in industrial facility for the production of fertilizers and chemicals in Egypt. The PG waste samples were characterized in terms of spectroscopic analysis (X-ray diffraction, X-ray fluorescence, IR spectra) and radiometric analysis (γ- and α-measurements). The γ-ray measurements showed that the average activity concentrations are 140 ± 12.6, 459 ± 36.7, 323 ± 28.4, 8.3 ± 0.76 and 64.3 ± 4.1 Bq/kg for U-238, Ra-226, Pb-210, Th-232 and K-40, respectively. The α-particle measurements of uranium isotopes showed that the average activity concentrations of U-238, U-235 and U-234 were 153 ± 9.8, 7 ± 0.38, 152 ± 10.4 Bq/kg, respectively. The average radiochemical recovery (%) of the destructive α-particle measurements is ∼70% with a resolution (FWHM) of ∼30 keV. Activity ratios of U-238/Ra-226 and U-238/Pb-210 were less than unity (i.e., <1) and equal to 0.31 ± 0.02 and 0.47 ± 0.16, respectively. The isotopic ratios of U-238/U-235 and U-238/U-234 (in PG and PR samples) were close to the normal values of ∼21.7 and ∼1, respectively and are not affected by the wet processing of phosphate rock (PR). The obtained results of PG waste samples were compared with phosphate rock (PR) samples. The radiation hazard indices are namely, radium activity index (Ra-Eq > 370 Bq/kg), total absorbed gamma dose rate (Dγr > 5 nGy/h) and radon emanation fraction (Rn-EF > 20%). Uncertainty of the sample counting was 95% confidence level of σ. The results indicated the necessity to find suitable routes to decrease and/or redistribute the radionuclide of environmental interest (i.e., Ra-226) in PG wastes, consequently to reduce its radiation impacts in the surrounding environment.