Average Activity Concentrations Of 226Ra Research Articles

A Study on the Radioactivity Level in Raw Materials, Final Products and Wastes of the Phosphate Fertilizer Industries in Bangladesh

A study on the detection of probable radionuclides and their activity concentrations in the raw material (phosphate rock), final product (fertilizer) and waste samples collected from all the phosphate fertilizer factories (total two factories—A Diammonium Phosphate, DAP and a Triple Super Phosphate, TSP factory) in Bangladesh were carried out. A total of seven types of samples (grossly divided into solid and liquid types); liquid waste, waste-mixed river water, normal river water, phosphate rock, phosphate fertilizer, solid waste and normal soil; were analyzed under this study. Raw material samples were collected only from the TSP fertilizer factory. Fertilizer, solid and liquid waste samples were collected from both the factories under study. Moreover, normal soil and natural surface water samples from the suitable areas adjacent to the factories were also collected for the comparison purpose. The samples were analyzed by gamma ray spectrometry technique using a Hyper-Pure Germanium (HPGe) detector of 40% relative efficiency. The analysis of the samples showed that only natural radionuclides such as 226Ra, 232Th and 40K were present in the samples and no traces of artificial radioactivity were found in any of the samples. 40K was found below the detection limit in some samples. The analysis of the samples in the case of TSP fertilizer factory showed that the average activity concentrations of 226Ra and 232Th and 40K in raw materials were 851.27 ± 7.10, 19.63 ± 6.57 and 54.06 ± 5.93 Bq/kg, respectively, in final product 211.90 ± 4.74, 42.48 ± 10.56 Bq/kg and ND (Not Detected), respectively, in solid waste 187.49 ± 4.88, 70.06 ± 11.76 and 289.27 ± 40.24 Bq/kg, respectively and in liquid waste 6.26 ± 0.63, 10.01 ± 1.39 Bq/L and ND, respectively. The measured results in the case of samples collected from DAP fertilizer factory showed that the average activity concentrations of 226Ra and 232Th and 40K in the final product were 17.31 ± 3.92, 69.74 ± 9.88 and 48.46 ± 17.22 Bq/kg, respectively, in solid waste 24.47 ± 4.15, 164.62 ± 11.08, 191.52 ± 33.74 Bq/kg, respectively and in liquid waste 3.59 ± 1.05, 37.08 ± 3.30 Bq/L and ND, respectively. Considering the stored raw materials and wastes the part of the ambient environment of the factory, radium equivalent activity, radiation hazard index and external annual effective dose to the workers and public due to these materials were also calculated and compared with world average values.

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.

Radioactivity measurements and radiation dose assessments due to natural radiation in Karabük (Turkey)

In this work, the radionuclide activity concentrations of 226Ra, 232Th and 40K in surface soils and radon levels in dwellings of Karabuk, Turkey were determined in order to evaluate the environmental radioactivity. Concentrations of 226Ra, 232Th and 40K radionuclides were determined using gamma spectrometry with using HPGe detector. The etch track detectors (CR-39) were used to determine the distribution of radon concentrations. The average activity concentrations for 226Ra, 232Th and 40K were found as 21.0, 23.5 and 363.5 Bq kg−1, respectively. The calculated average annual effective dose equivalent from the outdoor terrestrial gamma radiation from 226Ra, 232Th and 40K is 53.5 μSv y−1. The average radon concentration and annual effective dose equivalent of 222Rn in Karabuk dwellings were obtained 131.6 Bqm−3 and 3.32 mSv y−1, respectively. The evaluated data were compared with the data obtained from different countries.

Natural radioactivity and associated dose rates in soil samples from Kalpakkam, South India

The activity concentration of naturally occurring radioactive elements such as 226Ra, 232Th and 40K were measured for 46 soil samples collected in the vicinity of the Madras atomic power station, Kalpakkam, South India using gamma-ray spectroscopy. The average activity concentration of 226Ra, 232Th and 40K in soil samples were found to be 22.6 ± 12.6, 92.8 ± 44.3 and 434.1 ± 131.1 Bq kg(-1), respectively. The activity concentration of natural radionuclides is higher than the world average except for (226)Ra. The external absorbed gamma dose rates due to 226Ra, 232Th and 40K are observed to be 74.6 ± 30.8 nGy h(-1) with a corresponding annual effective dose of 91.5 ± 37.8 µSv y(-1), which are also above the world average. The values of radium equivalent activity and external hazard index are less than the world average. Whereas, the values of the radioactivity level index (I(γ)) and the total gamma dose rate were found to be above the required criterion.

Radiological impacts of natural radioactivity from phosphogypsum piles in Huelva (Spain)

The activity concentrations of 226Ra, 232Th and 40K have been measured by gamma spectroscopy in samples of soil collected from the different zones of around Huelva (Spain). The average activity concentrations of 226Ra (Bq kg −1) in the active phosphogypsum (PG) stacks, unrestored and restored zones were 647, 573 and 83 respectively. The corresponding values for 232Th and 40K (Bq kg −1) were 8, 10 and 25 and 33, 47 and 225 respectively. As a measure of radiation hazard to the occupational workers and public, the Ra equivalent activities, representative level index and dose rates due to natural radionuclides at 1 m above the ground surface were estimated. The average of absorbed dose rates due to 226Ra, 232Th and 40K (nGy/h) from active PG stacks, unrestored and restored zones are 284, 255 and 55.The calculated external γ-radiation average dose (mSv/y) received by the workers of the phosphogypsum piles are estimated to be 0.293, 0.262 and 0.057 which is far below the international agreed dose limit of 20 mSv/y ( ICRP-60, 1990) for workers. Also, the radiation dose to a member of the public resulting from the use of PG is negligible compared to the average annual effective dose from natural sources (2.4 mSv/y).

Radionuclide content of local and imported cements used in Egypt

The activity concentrations of natural and artificial gamma-ray emitting radionuclides in local andimported cement have been investigated during the period from 2000 to 2003 using a 50% HPGeγ-spectroscopy system. The total numbers of local and imported samples were29 and 8, respectively. The results showed a low activity concentration of137Cs inboth the local and imported samples. The only exception was found in one imported Portland cement(2.8 ± 0.2 Bq kg−1) and one local blast furnace slag cement(1.9 ± 0.3 Bq kg−1). The average activityconcentrations of 226Ra, 232Th and40K in localcement were 33 ± 17, 14 ± 2.4 and 45 ± 26 Bq kg−1, respectively, whereas those in imported cement were27 ± 7,8 ± 7 and 134 ± 22 Bq kg−1, respectively. The results showed that blast furnace slag cement contains thehighest level of natural radioactivity, whereas white cement contains the lowestlevels. The measured activity concentrations of the detected radionuclideswere compared with other measurements carried out in Egypt and elsewhere.Radium-equivalent activities were also calculated to assess the radiation hazardsarising from using such material in the construction of dwellings. Generally, theradium-equivalents of the analysed samples were smaller than the guideline limit of370 Bq kg−1.

Natural radioactivity and dose assessment for phosphate rocks from Wadi El-Mashash and El-Mahamid Mines, Egypt

The activity concentrations of 226Ra, 232Th and 40K have been measured by gamma spectroscopy (sodium iodide NaI(Tl) detector) in phosphate rock samples, collected from the Wadi El-Mashash, a site located in the central eastern desert, and El-Mahamid in the Nile valley, Egypt. The average activity concentrations of 226Ra, 232Th and 40K (Bq kg −1) in phosphate rocks were 665.8 ± 33.4, 329.4 ± 17 and 587.6 ± 29.4 for Wadi El-Mashash and 566.8 ± 28.6, 217.3 ± 11.8 and 560.1 ± 28 for El-Mahamid, respectively. The corresponding values for shale rocks were 85.2 ± 5.7, 93.3 ± 5.6 and 303.1 ± 15.2 Bq kg −1, respectively. As a measure of radiation hazard to the occupational workers and public, the Ra equivalent activities, representative level index and dose rates due to natural radionuclides at 1 m above the ground surface were estimated. The calculated external γ-radiation dose received by the workers of the phosphate mine are 538 and 418 μSv/y, which is far below the permitted dose of 20 mSv/y recommended by the International Commission of Radiation Protection [ICRP-60, 1990. Radiation Protection: 1990 Recommendation of the International Commission on Radiological Protection, Oxford, Pergamon Preis.] for workers.

Characteristics, spatial distribution and vertical profile of gamma-ray emitting radionuclides in the coastal environment of North Sinai

Radionuclide concentrations of beach and dune sand from various sites in Al-Arish city and surrounding area, North Sinai, Egypt, were measured. The sampling sites included locations in the local harbor, Al-Arish valley and Zaranik protected area. The results indicate that the activities of the products of 232Th and 226Ra series in samples from the harbor and along the beach were higher than those from non-coastal sites. The activity concentrations of 232Th for beach sand ranged from 2.3 to 506.5 Bq/kg with an average of 83.4 Bq/kg, while that for dune sand ranged from 2.2 to 15.1 Bq/kg with an average of 6.4 Bq/kg. The average activity concentration of 226Ra for beach sand was 56.0 Bq/kg (2.9–261.5 Bq/kg), while that for dune sand was 6.5 Bq/kg (3.0–14.7 Bq/kg). The average activity concentrations of 40K for beach and dune sand were 88.1 Bq/kg and 178.4 Bq/kg, respectively. Six depth profiles in the harbor area were measured up to a depth of 1 m within more than two years. These sets of measurements allowed the determination of the migration rate of black sand to be 0.094 cm/day. Samples with the smallest grain size (<0.2 mm) were found to have the highest level of activities, which were attributed to their high content of black sand. No risk exists for public health based on the calculated effective dose equivalent and the recommended limit of 5 mSv/y. On the other hand, local children and adults may receive doses higher than this recommended limit in two locations in the Zaranik protected area according to a model developed in this study.