Search Results
Abstract
Activity concentrations using gamma-ray spectrometer and distributions of natural radionuclides in soil samples collected were investigated to assess the environmental radioactivity and characterization of radiological hazard. The average concentrations of 238U, 232Th series and 40K in the 5 cm depth soil were 22.53, 33.43 and 406.62 Bq kg−1, respectively, which was within world median ranges in the UNSCEAR 2000 report. The average absorbed dose rate estimated by soil activity and annual effective doses were 49.32 nGy h−1 and 60.48 μSv, respectively. Since the soil is an important building material, the mean radium equivalent activity (Ra eq), external (H ex) and internal (H in) hazard index using various models given in the literature for the study area were evaluated as 101.72 Bq kg−1, 0.27 and 0.34, respectively, which were below the recommended limits. The effects of pH value, conductivity, true density and textural properties of soil samples on the natural radionuclide levels were also studied. The application of cluster analysis (CA) and principal component analysis (PCA), coupled with Pearson correlation coefficient analysis, were utilized to analyze the data, identify and clarify the effects of physico-chemical properties on natural radioactivity levels. The CA and PCA results showed that the former method yielded three distinctive groups of the soil variables whereas the latter one yielded the number of variables into three factors with 87.5% variance explanation.
Abstract
The main component of most building materials in Malaysia is rock. All rocks are known to contain natural radionuclides such as 238U and 232Th series as well as 40K. In order to estimate the radiological impact to the dweller, the level of radionuclides present in various building materials available in Malaysia were analyzed using γ-spectrometry. The radiation hazard indexes were calculated based on the above results. The results showed that the activity concentration of natural radionculides 238U, 232Th, 40K was between 19.0–42.2 Bq/kg, 16.5–28.8 Bq/kg and 243.3–614.2 Bq/kg, respectively. On the whole, the radionuclides concentration was still below the global average of 50 Bq/kg, 50 Bq/kg and 500 Bq/kg for 238U, 232Th, and 40K, respectively The radiation hazard indexes of the building materials were also lower than the maximum value suggested.
Abstract
Radioactivity levels in soil samples, collected from mid Rechna interfluvial region, Pakistan have been estimated by using gamma ray spectrometric technique. 226Ra, 232Th, the primordial radionuclide 40K and the artificial radionuclide 137Cs have been measured in the soil of the study area. The mean radioactivity levels of 226Ra, 232Th, 40K and 137Cs were found to be 49.0 ± 1.6, 62.4 ± 3.2, 670.6 ± 33.9 and 3.5 ± 0.4 Bq kg−1 respectively. The mean radium equivalent activity (Raeq), outdoor radiation hazard index (H out), indoor radiation hazard index (H in) and terrestrial absorbed dose rate for the area under study were determined as 189.9 ± 8.8 Bq kg−1, 0.51, 0.65 and 70.1 nGy h−1 respectively. The annual effective dose to the public was estimated to be 0.43 mSv. The measured values are comparable with other global radioactivity measurements and are found to be safe for public and environment.
Abstract
The concentration of radioactive226Ra,232Th and40K in building and ceramic materials of Bangladesh was investigated by γ-spectrometry with two HPGe detectors. Radium equivalent activities, representative level index values, criterion formula, emanation coefficients and222Rn mass exhalation rates were estimated for the radiation hazard of the natural radioactivity in the materials. The activity concentrations of the natural radionuclides, radium equivalent activities, emanation coefficients and222Rn mass exhalation rates are compared with the corresponding values for building and ceramic materials of different countries. The radium equivalent activities in the samples varied between 30.9 (mosaic stone) and 328.0 Bq·kg−1 (gypsum). The emanation coefficient of the materials ranged from 7.83 (cement) to 33.0% (soil) and the222Rn mass exhalation rate ranged from 2.31 (stone chips) to 118.0 μBq·kg−1·s−1 (gypsum).
Abstract
A study on the concentration of natural and fallout radionuclides in environmental samples collected from different localities of Islamabad was performed. For the determination of gamma-emitters such as 238U, 232Th, 40K and 137Cs high purity germanium (HPGe) detector was used while for the analysis of 90Sr, a beta-emitter, liquid scintillation counting system was used. The indoor absorbed dose rate was measured by a CaF2 : Dy thermoluminescence detector. Other radiation parameters were also determined to evaluate the radiation hazard. All the results were well within the permissible limits showing that there is no radiation hazard in the environment of Islamabad.
Abstract
Iodine-129 may have no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioiodine contamination. Since 1943, 129I/127I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer living near a nuclear reprocessing facility have contained 129I, which are 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of 129I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that 129I, may be helpful to evaluate past radiation hazard from fission products.
Abstract
A new generation of ion mobility spectrometers has been designed especially for the environmental monitoring due to toxic compounds in ambient air: phosgene, halocarbons, isofluorane, halothane, formaldehyde, ethylenoxide, acrolein, chemical warfares and many others. The IMS is equipped by means of tritium ionization sources, which have lower radiation hazards than nickel-63 sources. Aromatics are monitored by means of a special version using photoionization. Minimal detectable concentrations are in the ppb-range, mostly even below.
Abstract
appeared in the Journal of Radioanalytical and Nuclear Chemistry, Vol. 243, No. 2 (2000) 467–472.During the electronic submission of the paper the file was damaged, and parts were left out. In order to correct this, we publish the correct paper as a whole.Iodine-129 may be no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioactive contamination. Since 1943, 129I/127I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer, living near a nuclear reprocessing facility have contained 129I which is 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of 129I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that 129I may be helpful to evaluate past radiation hazard from fission products.
Abstract
People are exposed to ionizing radiation from the radionuclides that are present in different types of a natural sources, of which building materials is one of the most important sources. Radionuclides in building materials belonging to 238U, 232Th series as well as radioisotope of Potassium 40K are the major contributors of outdoor terrestrial natural radiation. This study is the first ever in Iraq. In order to estimate the radiological impact to the dweller, the activity concentration of radionuclides present in various Iraqi building materials were analyzed using Gamma-spectrometry. The radiation hazard indexes were calculated based on the above results. The results showed that the activity concentration of 238U, 232Th and 40K was between 32.9 Bq/kg (Najaf gypsum)–179.32 Bq/kg (Karbala cement), 1.98 Bq/kg (Najaf sand)–17.43 Bq/kg (Qadisiya brick) and 108.73 Bq/kg (Karbala sand)–977.79 Bq/kg (Najaf brick), respectively. All values of Radium equivalent activities were found to be less than the maximum permissible limit and the internal hazard indexes (except Karbala cement) were less than unity for the radiation hazard. Some samples have external annual dose and external hazard index values greater than unity.
Abstract
River sediment depositions on the bottom of rivers most frequently consist of sand and gravel particles, which make them particularly valuable for the building construction. Knowledge of radioactivity present in building material enables one to assess any possible radiological hazard to mankind by the use of such materials. The natural radionuclide (238U, 232Th and 40K) contents have been analyzed for the recently excavated sediment samples of Cauvery, Vellar, Ponnaiyar and Palaru rivers with an aim of evaluating the radiation hazard nature. To know the radiological characteristics of the sediment, the different radiological parameters are calculated. Natural radioactivity level is higher in Palaru river and it is lower in Vellar river sediments. In all the rivers, concentration of 238U is decreased, and concentrations of 232Th and 40K are increased towards the river mouth. Granulometric analysis shows that the sand is the main constituent in all the river sediment samples. Content of sand is gradually decreased, and contents of silt and clay are gradually increased towards the river mouth. Cluster analysis was carried out to find the similarity level between the radioactivity and granulometric measurements. The radioactivity level of all the four river sediments mainly depends upon the contents of silt and clay. Averages of the all calculated radiation hazard indices are lower than recommended level in Cauvery, Vellar and Ponnaiyar river sediments. Therefore, the sediment of the above rivers does not pose any significant radiological threat to the population when it is used as a building construction material.
