232Th Series Research Articles

Distribution of natural radionuclides and assessment of the associated hazards in the environment of Marsa Alam-Shalateen area, Red Sea coast, Egypt

Radiological aspects of water, soil and shore sediments resources in Marsa Alam-Shalateen area, Red Sea coast, Egypt, were investigated with the aim of presenting background about the radiological levels and assessing the associated hazards. The results of study are intended to support the governmental authorities as regards the future-natural resources management. Sixty nine environmental samples (30 water, 33 soil and 6 shore sediments samples) were collected in 2015 and analyzed for Ra-226 (U-238) series, Th-232 series, K-40 and Cs-137 radionuclides using Hyper-Pure Germanium (HPGe) detector. For all samples, the activity concentrations of Cs-137 radionuclide are under the detection limit of the used analytical procedures. As regards the water resources, the Th-232 activity concentrations in the major part of water samples were under the detection limit. The Ra-226 activity concentrations ranged from <0.7 to 7.6 Bq L−1 and from <0.7 to 6.31 Bq L−1 for groundwater and sea water samples, respectively. All the desalinized water and 50% from wastewaters were clear of Ra-226 activity concentration. The K-40 ranged from <3 to 32.84 Bq L−1, from <3 to 38.17 Bq L−1, from <3 to 54.31 Bq L−1 and from <3 to 40.91 Bq L−1 for groundwater, sea water, desalinized water and wastewater samples, respectively. Radiologically, all fresh waters, safe for drinking except Al Gaheliya well showed Ra-226 activity concentration higher than the guidance level recommended by the WHO.For soil cover, the average activity concentrations of Ra-226, Th-232 and K-40 of the carbonaceous soil samples were 18.45, 16.78, and 334.35 Bq kg−1, respectively. While for the siliceous soil samples, they were 10.24, 8.68 and 234.47 Bq kg−1, respectively. For shore sediment samples having calcareous nature, the average concentrations of Ra-226, Th-232 and K-40 were 10.76, 9.86 and 304.74 Bq Kg−1. There are no risks for people health based on the calculated radiological hazard indices. However, people could be affected by radiation in one site (Marsa Alam-Shelateen Road km 33), where the representative level index (1.052 Bq kg−1) and absorbed gamma dose rate (66.5 nGy h−1) exceed the maximum permissible limits.

Radionuclide concentration variations in the fuel and residues of oil shale-fired power plants: Estimations of the radiological characteristics over a 2-year period

Several multi-day samplings were conducted over a 2-year period from an oil shale-fired power plant operating with pulverized fuel type of boilers that were equipped with either novel integrated desulphurization system and bag filters or with electrostatic precipitators. Oil shale, bottom ash and fly ash samples were collected and radionuclides from the 238U and 232Th series as well as 40K were determined. The work aimed at determining possible variations in the concentrations of naturally occurring radionuclides within the collected samples and detect the sources of these fluctuations. During the continuous multi-day samplings, various boiler parameters were recorded as well. With couple of exceptions, no statistically significant differences were detected (significance level 0.05) between the measured radionuclide mean values in various ash samples within the same sampling. When comparing the results between multiple years and samplings, no statistically significant variations were observed between 238U and 226Ra values. However, there were significant differences between the values in the fly ashes when comparing 210Pb, 40K, 228Ra and 232Th values between the various samplings. In all cases the radionuclide activity concentrations in the specific fly ash remained under 100 Bq kg−1, posing no radiological concerns when using this material as an additive in construction or building materials. Correlation analysis between the registered boiler parameters and measured radionuclide activity concentrations showed weak or no correlation. The obtained results suggest that the main sources of variations are due to the characteristics of the used fuel. The changes in the radionuclide activity concentrations between multiple years were in general rather modest. The radionuclide activity concentrations varied dominantly between 4% and 15% from the measured mean within the same sampling. The relative standard deviation was however within the same range as the relative measurement uncertainty, suggesting that the main component of fluctuations is derived from the measurement method and approach.The obtained results indicate that representativeness of the data over a longer time period is valid only when a fuel with a similar composition is used and when the combustion boilers operate with a uniform setup (same boiler type and purification system). The results and the accompanying statistical analysis clearly demonstrated that in order to obtain data with higher reliability, a repeated multi-day sampling should be organized and combined with the registered boiler technical and operational parameters.

Measurement of naturally occurring radioactive materials, 238U and 232Th: anomalies in photopeak selection

There are more than 200 photopeaks of various daughter radionuclides of 238U and 232Th series, some of which have been randomly used for quantitative measurement of U/Th in natural samples. It has been observed that arbitrariness in photopeak selection may fail to stipulate statistically consistent data. This paper judiciously selects set of three photopeaks from each series whose respective averages could present statistically reliable measurement of 238U and 232Th based on minimum relative standard deviation (RSD) under the selected photopeaks. RSD is also proposed as an important parameter in NORM measurement.

Intercomparison NaI(Tl) and HPGe spectrometry to studies of natural radioactivity on geological samples

In this study, in situ gamma spectra using NaI(Tl) detector have been compared with the laboratory measurements by using HPGe detector on geological samples. The results for measuring naturally occurring terrestrial gamma radiation of 40K and the decay series of 232Th and, 238U respectively of both detectors show a maximum deviation about 5%. The mass activities series from both detectors were checked for coherence using proficiency test procedure from the International Atomic Energy Agency. The reliability and precision pass for final scores for all the analytical determinations of are received “acceptable” for all radionuclides.

Model standards in nuclear physics methods for determination of an event date

The method of standard sets is considered without use of a reference sample. In this method a set of ordered sequences of the activities of 232Th, 235U and 238U series radionuclides is used. The ordering of nuclide activities is determined by solving a system of Bateman–Rubinson differential equations. The calculated activities of nuclides are arranged in the form of a table of standards. The table of standards serves as an internal mathematical reference (the reference sample).

Comparison of226Ra/238U and228Th/228Ra Disequilibrium With Weathering Indices In Beach Sand Sediments From Greece

Weathering indices can be used to quantify weathering of rocks at various stages of weathering processes and provide a better understanding of element mobility during weathering. Various weathering indices have been proposed in the literature worldwide. In the present work, radioactive secular disequilibrium has been used to determine weathering extent. Thirty-seven samples from Kavala and thirty from Sithonia beach sands, all of them being the weathering products of the local granitic plutons, are studied for their secular disequilibrium in both 238U and 232Th series (226Ra/238U and 228Ra/228Th respectively). The results are compared to weathering indices already in use worldwide and suggest a consistent correlation with WIP (alkaline and alkaline-earth element leaching) and PWI (silica leaching) for the well and very well sorted sands and for the heavy minerals of Kavala. This study suggests that with an appropriate choice of the weathering index and samples both U-series and weathering index can recover the extent of chemical weathering.

238U and 232Th concentrations measured in different medical drugs by using solid-state nuclear track detectors and resulting radiation doses to the skin of patients

Urban populations in Morocco receive free medical drugs as prescribed by doctors in district health centres. To explore the exposure pathway of 238U and 232Th and their decay products on the skin of patients, these radionuclides were measured in various medical drugs by using solid-state nuclear track detectors (SSNTDs).The measured concentrations range of 238U and 232Th in the medical drug samples of interest vary from (4.3 ± 0.3) to (11.1 ± 0.7) mBq l−1 and (0.49 ± 0.03) to (1.3 ± 0.1) mBq l−1, respectively. A new dosimetric model, based on the concept of specific alpha-dose and alpha-particle residual energy, was developed for evaluating radiation doses to skin following the application of different medical drugs by patients. The maximum total equivalent effective dose to skin due to the 238U and 232Th series from cutaneous application of different medical drugs by patients was found to be 2.8 mSv year−1 cm−2.

Radionuclides and toxic chemical elements in the transboundary Kyrgyzstan–Kazakhstan rivers

The paper presents the results of radiation surveying and determination of radionuclide and elemental composition in water objects (soil, bottom sediments, water) of the transboundary rivers Shu, Shor-Koo, Aksu, Karabalta, Toktas as well as of Tasotkel water-storage in Kazakhstan in vicinity of the border with Kyrgyzstan. Increased contents of natural radionuclides of 238U and 232Th series, As, Co, Cs, Cu, Hf, Mo, Pb, Sb, Sc, Zn, Zr and rare earth elements were observed in soil and bottom sediment samples. Increased contents of the following toxic elements were revealed in water samples: B, As, Mo, Ba, U. Negative influence of radiation-hazardous sites in Kyrgyzstan on the contamination of the transboundary rivers with natural radionuclides and toxic elements was revealed.

Nuclide Spectra of Activities of Thorium, Uranium Series and Application in Gamma-spectrometry of Point Technogenic Samples

The radioactive nuclei decay of the nuclides in the 232Th, 235U and 238U series is under consideration. The Bateman-Rubinson system of differential equations is applied. The activity of any n-th nuclide of the series has been calculated. The standard nuclide spectra are found and are compared with experimental nuclide spectra of activities. The results of the measurements are the time parameters, which determine the event date. The examples of the measurement of the experimental nuclide spectra in the nuclear gamma spectrometry of the point technogenic samples have been considered.

Measurement of the total activity concentrations of Libyan oil scale

Twenty-three oil scale samples obtained from the Libyan oil and gas industry production facilities onshore have been measured using high-resolution gamma-ray spectrometry with a shielded HPGe detector, the work being carried out within the Environmental Radioactivity Laboratory at the University of Surrey. The main objectives of this work were to determine the extent to which the predominant radionuclides associated with the uranium and thorium natural decay chains were in secular equilibrium with their decay progeny, also to compare differences between the total activity concentrations (TAC) in secular equilibrium and disequilibrium and to evaluate the measured activities for the predominant gamma-ray emitting decay radionuclides within the 232Th and 238U chains. The oil scale NORM samples did not exhibit radioactive equilibrium between the decay progeny and longer-lived parent radionuclides of the 238U and 232Th series.

Assessment of the Heavy Metals and Natural Radioactivity in Phosphate Mines and Occupational Health Effects at Some Egyptian Regions

In this work the specific activities of natural radionuclides namely (238U series, 232Th series and 40K) has been measured in collected sedimentary phosphate deposits samples from El-Hamraween, El-Quser and Safaga phosphate mines in Egypt. HPGe γ-spectrometry was used. This study was undertaken to estimate the radiation hazard indices in phosphate mining at the studied mines on their occupational workers, and to establish correlation relationships between the some measured heavy metals such as As, Cd and Pb in blood workers and their concentration in phosphate rock ores. As well as determination the biomarkers in the blood workers such as malondialdehyde (MDA) and superoxide dismutase (SOD). The phosphate mine sample of El-Hamrawein has the lowest activity concentration of 226Ra, 232Th and 40K in compared to the phosphate mine samples of El-Quseir and Safaga (El-Hamrawein<El-Quseir<Safaga). The activity concentrations of all analyzed investigated radionuclides considerably fluctuated; for 226Ra activity concentrations varied from 222.4 to 255.8 Bq kg-1, 122.4 to 188.3 Bq kg-1 and 115.4 to 165.8 Bq kg-1 for Safaga, El-Quseir and El- Hamrawein, respectively. For 232Th activity concentrations varied from 135.6 to 212.3 Bq kg-1, 112.8 to 167.4 Bq kg-1 and 132.8 to 188.6 Bq kg-1 for Safaga, El-Quseir and El-Hamrawein, respectively. For 40K activity concentrations varied from 225.2 to 312.8 Bq kg-1, 168.7 to 268.9 Bq kg-1 and 95.2 to 155.8 Bq kg-1 for Safaga, El-Quseir and El-Hamrawein respectively. The workers of old ages have higher concentration of the investigated heavy metals than young ages. There is a good relation between the concentration of the investigated metals in phosphate mine samples and their concentration in blood of the occupational workers in these mines.

Assessment of the Heavy Metals and Natural Radioactivity in Phosphate Mines and Occupational Health Effects at Some Egyptian Regions

In this work, the specific activities of natural radionuclides, namely 238U series, 232Th series and 40K, have been measured in collected sedimentary phosphate deposits samples from El-Hamraween, El-Quser and Safaga phosphate mines in Egypt. HPGe γ-spectrometry was used. This study was undertaken to estimate the radiation hazard indices in phosphate mining at the studied mines on their occupational workers, to establish correlation relationships between the some measured heavy metals such as As, Cd and Pb in blood workers and their concentration in phosphate rock ores and to determinate the biomarkers in the blood workers such as malondialdehyde (MDA) and superoxide dismutase (SOD). The phosphate mine sample of El-Hamrawein has the lowest activity concentration of 226Ra, 232Th and 40K in comparison to the phosphate mine samples of El-Quseir and Safaga (El-Hamrawein 226Ra activity concentrations varied from 222.4 to 255.8 Bq·kg-1, 122.4 to 188.3 Bq·kg-1 and 115.4 to 165.8 Bq·kg-1 for Safaga, El-Quseir and El-Hamrawein, respectively. For 232Th activity concentrations varied from 135.6 to 212.3 Bq·kg-1, 112.8 to 167.4 Bq·kg-1 and 132.8 to 188.6 Bq·kg-1 for Safaga, El-Quseir and El-Hamrawein, respectively. For 40K activity concentrations varied from 225.2 to 312.8 Bq·kg-1, 168.7 to 268.9 Bq·kg-1 and 95.2 to 155.8 Bq·kg-1 for Safaga, El-Quseir and El-Hamrawein, respectively. The workers of old ages have higher concentration of the investigated heavy metals than those of young ages. There is a good relation between the concentration of the investigated metals in phosphate mine samples and their concentration in blood of the occupational workers in these mines.

The dose of gamma radiation from building materials and soil

Abstract The radioactivity of some structural building materials, rows, binders, and final construction products, originating from Serbia or imported from other countries, was investigated in the current study by using the standard HPGe gamma spectrometry. The absorbed dose in the air was computed by the method of buildup factors for models of the room with the walls of concrete, gas-concrete, brick and stone. Using the conversion coefficients obtained by interpolation of the International Commission on Radiobiological Protection (ICRP) equivalent doses for isotropic irradiation, the corresponding average indoor effective dose from the radiation of building materials of 0.24 mSv·y−1 was determined. The outdoor dose of 0.047 mSv·y−1 was estimated on the basis of values of the specific absorbed dose rates calculated for the radiation of the series of 238U, 232Th and 40K from the ground and covering materials. The literature values of the effective dose conversion coefficients for ground geometry were applied as well as the published data for content of the radionuclides in the soil.

Contamination and Radionuclides Concentration in Imported Canned Foodstuffs in Baghdad Markets

This work was concerned with study the contamination and concentration of natural and man-made radioactivity 40K, 137Cs, 214Bi (238U series) and 228Ac (232Th series) in 19 different imported foodstuffs canned samples (Mushrooms, Black Olives, Broad Beans, Peaches, Sweet Corn, Tomato Past, Green Peas, Chick Peas, Baby milk 1,2,3 and Full milk powder) , were collected from locally markets in different regions in Baghdad city. Samples were analyzed by high-purity germanium (HPGe) detector gamma spectrometer systems from Canberra, with high resolution (2.0 keV at 1332 keV) and relative efficiency of ~30% for 137Cs (661.7 keV) and provide (Software Genie 2000 from Canberra). From the data obtained, the activity concentrations (Bq/kg or Bq/l) for 40K, 137Cs, 214Bi and 228Ac in above foodstuff samples were measured. It was found that these values lie within the worldwide range for radioactivity in food. The mean value of radium equivalent activity (Raeq) in all samples it was below the threshold value of 370 Bq/kg. The all value of indoor and outdoor annual effective dose equivalent in samples it was lower than the world average values (0.45 mSv/y for indoor and 0.07 mSv/y for outdoor).

Contamination and Radionuclides Concentration in Imported Canned Foodstuffs in Baghdad Markets

This work was concerned with study the contamination and concentration of natural and man-made radioactivity 40K, 137Cs, 214Bi (238U series) and 228Ac (232Th series) in 19 different imported foodstuffs canned samples (Mushrooms, Black Olives, Broad Beans, Peaches, Sweet Corn, Tomato Past, Green Peas, Chick Peas, Baby milk 1,2,3 and Full milk powder) , were collected from locally markets in different regions in Baghdad city. Samples were analyzed by high-purity germanium (HPGe) detector gamma spectrometer systems from Canberra, with high resolution (2.0 keV at 1332 keV) and relative efficiency of ~30% for 137Cs (661.7 keV) and provide (Software Genie 2000 from Canberra). From the data obtained, the activity concentrations (Bq/kg or Bq/l) for 40K, 137Cs, 214Bi and 228Ac in above foodstuff samples were measured. It was found that these values lie within the worldwide range for radioactivity in food. The mean value of radium equivalent activity (Raeq) in all samples it was below the threshold value of 370 Bq/kg. The all value of indoor and outdoor annual effective dose equivalent in samples it was lower than the world average values (0.45 mSv/y for indoor and 0.07 mSv/y for outdoor).

Contamination and Radionuclides Concentration in Imported Canned Foodstuffs in Baghdad Markets

This work was concerned with study the contamination and concentration of natural and man-made radioactivity 40K, 137Cs, 214Bi (238U series) and 228Ac (232Th series) in 19 different imported foodstuffs canned samples (Mushrooms, Black Olives, Broad Beans, Peaches, Sweet Corn, Tomato Past, Green Peas, Chick Peas, Baby milk 1,2,3 and Full milk powder) , were collected from locally markets in different regions in Baghdad city. Samples were analyzed by high-purity germanium (HPGe) detector gamma spectrometer systems from Canberra, with high resolution (2.0 keV at 1332 keV) and relative efficiency of ~30% for 137Cs (661.7 keV) and provide (Software Genie 2000 from Canberra). From the data obtained, the activity concentrations (Bq/kg or Bq/l) for 40K, 137Cs, 214Bi and 228Ac in above foodstuff samples were measured. It was found that these values lie within the worldwide range for radioactivity in food. The mean value of radium equivalent activity (Raeq) in all samples it was below the threshold value of 370 Bq/kg. The all value of indoor and outdoor annual effective dose equivalent in samples it was lower than the world average values (0.45 mSv/y for indoor and 0.07 mSv/y for outdoor).

Measurement of intrinsic radioactive backgrounds from the 137Cs and U/Th chains in CsI(Tl) crystals**Supported by National Natural Science Foundation of China (11275107, 11175099)

The inorganic CsI(Tl) crystal scintillator is a candidate anti-compton detector for the China Dark matter Experiment. Studying the intrinsic radiopurity of the CsI(Tl) crystal is an issue of major importance. The timing, energy and spatial correlations, as well as the capability of pulse shape discrimination provide powerful methods for the measurement of intrinsic radiopurities. The experimental design, detector performance and event-selection algorithms are described. A total of 359×3 kg-days data from three prototypes of CsI(Tl) crystals were taken at China Jinping Underground Laboratory (CJPL), which offers a good shielding environment. The contamination levels of internal isotopes from 137Cs, 232Th and 238U series, as well as the upper bounds of 235U series are reported. Identification of the whole α peaks from U/Th decay chains and derivation of those corresponding quenching factors are achieved.

A Comparison Study of Soil Samples from Sinai Province in Egypt by Using X-Ray Diffraction and Gamma-Ray Analysis

Ten soil samples from Jabal Al Qur, Wadi Baba, and Wadi Sieh in Sinai, Egypt, were analyzed by XRD spectroscopy. The XRD spectroscopy results indicate that the major, minor and trace constituents varied from one sample to another. Samples were also analyzed by HPGe gamma spectrometer to determine the activity concentration of U-238, Th-232 series and K-40. The concentrations for 238U ranged from 57.03 to 4220.41 Bq/kg with an average 1110.75 Bq/kg, for 232Th, ranged from 13.55 to130.46 Bq/kg with an average 71.85 Bq/Kg. The concentrations for 40K were in the range from 12.18 to 948.93 Bq/kg with an average value 457.09 Bq/kg. The average activity concentration values of 226Ra, 232Th, and 40K, in all the collected samples were higher than the world average. The radium equivalent (Req), absorbed dose rate (DR), the effective dose rate (Deff), and hazard indices resulted due to the natural radionuclides in soil are also calculated. The Results show that the study area is not safe for human and environments.

Origin of thorium deposits in Kerala beach sands

The origin of the thorium deposits on the West Coast of India is not well established though a number of studies on the various aspects of these deposits have been carried out for more than 50 years. The deposits are believed to be washed down from highlands through water streams. It is proposed that atom ratios of various radioactive and stable products in the uranium and thorium series as a function of time could be effectively used for the purpose. Accordingly, the various ratios have been calculated as a function of the age in the time range of 100-70,000 years. The stable products are included for the first time.Pb-208/Th-232 in Th-232 series, Pb-207/U-235, Pb-207/Pa-231, and in U-235 series and Pb-206/U-238, Pb-206/U-234, Pb-206/Th-230, and Pb206/Ra226 in U-238 series, are presented. The ratios show significant variations in the time range studied. The ratio Pb-206/Pb-207 from the two uranium series is of interest and is examined. This ratio shows a variation of up to 100 times whereas, the natural isotopic ratio is around unity. It is suggested that an extensive measurement of these ratios and their correlation in samples from the hypothesized source in highlands, in river beds, and on the beach sand might give some idea of the transport path for these minerals. Further, it is suggested to measure the ratio of all the lead isotopes from the three series with Pb-204 which is purely of primordial in origin which would also be useful to indicate the contribution from radiogenic sources. In order to undertake such a project which, of course, involves many disciplines large efforts in sampling, in modeling of possible transport paths and strategies for analysis are required.

Monte Carlo determination of the infinite matrix dose rate correction factors for 250 μm quartz and TLD500 chip

A new approach based on the Monte Carlo simulation is used to calculate the infinite matrix dose rate correction factors of gamma, beta and internal conversion radiations for 250 μm diameter grains of quartz and TLD500 chips. Here, the dependence of the correction factor on the radiation energy is initially calculated for each type of emitted particle and with this result the correction factors for the 232Th and 238U series and 40K are determined. This analysis is made for dry soil and also for different levels of water content in it. The obtained beta correction factors for quartz are in good agreement with those previously reported. For the TLD500 chip certain differences with previously reported data are found. The analysis of the gamma water correction factor for quartz based on Zimmerman equation shows the correspondence with the similar correction factor for electrons. In the case of TLD500 chip a gamma water correction factor value of 1.0 was found.