Natural radioactivity in some building materials and by-products of Shaanxi, China

The concentration of ²²⁶Ra, ²³²Th and ⁴⁰K has been determined by -ray spectrometry. The measured activity in the selected building materials and by-products of coal fired power plants ranges from 21.5 to 91.3 Bq·kg^–1, 15.4 to 63.2 Bq·kg^–1 and 83.2 to 683.9 Bq·kg^–1 for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. The results were compared with the reported data of other countries and with the world average activity of soil. The radium equivalent activities values of all building materials are lower than the limit of 370 Bq·kg^–1, equivalent to a -dose of 1.5 mSv·y^–1. The values of the external hazard index and the internal radiation hazard index are less than unity.This work was supported by the Provincial Natural Sciences Foundation of Shaanxi through Grants 2003D04 and by the Science Foundation of Shaanxi Normal University. Gratitude is expressed to J. Xiaowei, W. Xiaolei, L. Zhendong for assisting in sampling.     

Natural radioactivity in some building materials and by-products of Shaanxi, China

The concentration of ²²⁶Ra, ²³²Th and ⁴⁰K has been determined by -ray spectrometry. The measured activity in the selected building materials and by-products of coal fired power plants ranges from 21.5 to 91.3 Bq·kg^–1, 15.4 to 63.2 Bq·kg^–1 and 83.2 to 683.9 Bq·kg^–1 for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. The results were compared with the reported data of other countries and with the world average activity of soil. The radium equivalent activities values of all building materials are lower than the limit of 370 Bq·kg^–1, equivalent to a -dose of 1.5 mSv·y^–1. The values of the external hazard index and the internal radiation hazard index are less than unity.This work was supported by the Provincial Natural Sciences Foundation of Shaanxi through Grants 2003D04 and by the Science Foundation of Shaanxi Normal University. Gratitude is expressed to J. Xiaowei, W. Xiaolei, L. Zhendong for assisting in sampling.     

Natural radioactivity and radiological hazards of building materials in Xianyang,China

Common building materials collected from Xianyang, China were analyzed for the natural radioactivity of ²²⁶Ra, ²³²Th and ⁴⁰K using γ-ray spectroscopy. The average activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied building materials ranges from 13.4 to 69.9, 13.1–99.1 and 124.7–915.1 Bq kg^?1, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries and with the worldwide average activity of soil. To assess the radiation hazard of the natural radioactivity in all samples to the people, the radium equivalent activity, external hazard index, internal hazard index, indoor absorbed dose rate and total annual effective dose were estimated. The radium equivalent activities of the studied samples are below the internationally accepted values. The external hazard index and internal hazard index of all analyzed building materials are less than unity. The mean values of indoor absorbed dose rate for all building materials except for lime are higher than the world population-weighted average of 84 nGy h^?1 and the total annual effective dose values of building materials are lower than 1 mSv y^?1 except for some cyan brick samples. The study shows the measured building materials do not pose significant source of radiation hazard and are safe for use in the construction of dwellings.     

Natural radioactivity of spring water used as spas in Spain

Spring waters used as spas may contain significant amounts of natural radionuclides, so, in some circunstances, a radiation protection issue can arise for the population and/or the spas workers. EU has identified some groups of employees to be exposed to natural radiation in the 1996 Euratom Directive. Among these are workers of thermal spas who may be exposed to high radiation doses due to high radon concentrations in indoor air. In order to evaluate the potencial risk of the spring waters used as spas, gross-α and gross-β activity, ²²⁶Ra and ²²²Rn concentration levels were measured in 82 spas all over the country. Gross-alpha and gross-beta concentrations ranged from LLD to 17 Bq·l⁻¹ and from LLD to 60 Bq·l⁻¹, respectively. ²²⁶Ra concentrations ranged from <4 to 3,660 mBq·l⁻¹. ²²²Rn concentrations ranged from <4 to 1868 Bq·l⁻¹. Correlations between ²²⁶Ra concentrations and gross-α activity were obtained.     

Natural radioactivity levels in river, stream and drinking water of the northwestern areas of Pakistan

Natural radioactivity in the aquatic media has been determined by collecting samples of river, stream and drinking water from the northwestern areas of Pakistan. The concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th have been measured using a low background gamma-spectrometer and a 10 cm³ planar intrinsic high purity germanium detector. The annual ingestion of these radionuclides, using local consumption rates (average over the whole population) of 0.9 l^.d^-1, were estimated to be 49.2, 6.2 and 1.1 Bq^.y^-1 for ⁴⁰K, ²²⁶Ra and ²³²Th, respectively. A comparison of the annual intakes of these radionuclides, using annual consumption rates of NCRP, ICRP and FBSP shows that the contribution from natural radionuclides to annual intake is slightly greater for NCRP than for ICRP and FBSP consumption rates. However, the estimated values and weighted means of these radionuclides compare well with the world average. The annual effective dose equivalent from drinking water was found to be 3.6^.10^-6 mSv^.y^-1 (²²⁶Ra), 3.2^.10^-12 mSv^.y^-1 (²³²Th) and 2.1^.10^-6 mSv^.y^-1 (⁴⁰K). These values are lower than those given by NCRP.     

Natural radioactivity of building materials

Experiments were designed to measure trace uranium concentration and the rate of radon exhalation from masonry structural materials, both bare and surface finished and coated. LR115 cellulose nitrate track detectors were used to record the alpha emission from structural material surface. Fission track, neutron activation and fluorometric analysis methods were used to determine the uranium content. Most types of paints studied will reduce alpha contribution and radon emanation from building materials.     

Natural radioactivity in soil samples of Kocaeli basin, Turkey

The city of Kocaeli is in the western part of Anatolia in Turkey and has a population of approximately 1.000.000. There is no information about radioactivity in the Kocaeli soils samples so far. For this reason, the concentrations of the natural radionuclides in soil samples from 27 different sampling stations in Kocaeli Basin and its surroundings have been determined. The results have been compared with other radioactivity measurements in different country"s soils. The typical concentrations of ¹³⁷Cs, ²³⁸U, ⁴⁰K, ²²⁶Ra, ²³²Th found in surface soil samples ranged from 2±0.6 to 25±6 Bq/kg, from 11±4 to 49±10 Bq/kg, from 161±30 to 964±127 Bq/kg, from 10±4 to 58±11 Bq/kg, and from 11±3 to 65±13 Bq/kg, respectively.     

Natural radioactivity level and radiological hazard assessment of commonly used building material in Xining,China

Natural radioactivity of the commonly used building materials in Xining of China was measured using gamma-ray spectrometer system comprising a NaI(Tl) detector. Radioactivity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied samples range from 11.6 to 120.6, 10.2 to 107.1 and 228.0 to 1,036.2 Bq kg^?1, respectively. The concentrations for these natural radionuclides were compared with the reported data of other countries and the mean value for soil. Radium equivalent activity, indoor air absorbed dose rate, annual effective dose rate as well as external and internal hazard indices were calculated to assess radiological hazards for people living in dwelling made of the building materials. The radiological hazard assessment results show that the studied building materials, except for some aerated concrete block samples, are safe for use in construction of dwellings in the study area and do not pose any significant source of radiation hazard.     

Natural radioactivity in springs of Sverdlovsk region,Middle Urals,Russia

Journal of Radioanalytical and Nuclear Chemistry - Activity concentrations of natural radionuclides were determined in water from 31 springs of Sverdlovsk region, Middle Urals, Russia. Activity...     

Natural radioactivity in Algerian bottled mineral waters

The activity concentrations of some radionuclides in Algerian bottled mineral waters were determined using CR-39 nuclear track detectors for ²²²Rn, and a high resolution gamma-ray spectrometry for ²²⁶Ra, ²³²Th and ⁴⁰K. The mean specific activities of ²²²Rn , ²²⁶Ra, ²³¹Th and ⁴⁰K in the drinking mineral waters were 7±4 Bq^.l^-1, 26±11 mBq^.l^-1, 30±13 mBq^.l^-1 and 1±0.5 Bq^.l^-1, respectively. These values are comparable with concentrations reported for other countries. The effective doses due to intake of these radionuclides as a consequence of direct consumption of drinking mineral waters have been determined. The estimated effective doses were 56.8 mSv^.y^-1 for ²²²Rn, 3.94 mSv^.y^-1 for ²²⁶Ra, 4.45 mSv^.y^-1 for ²³²Th and 3.33 mSv^.y^-1 for ⁴⁰K. Contribution of these radionuclides to the effective dose due to ingestion and inhalation of all terrestrial radionuclides is estimated to be only 0.012%.     

Natural radioactivity in bioassay by alpha-spectrometry measurements

Personnel of nuclear facilities are checked regularly for internal contamination by bioassay measurements. Although these persons are generally not involved in any incident, natural radioactivity from U, Th and Ra can be found in their urine or faeces. Uranium total activity in urine has been found with a range of 0.051 to 3.0 mBq/24 h and in faeces from 14.5 to 380 mBq/d. ²³⁴U/²³⁸U ratio for urine is 1.48 but this ratio varies from 0.47 to 19. By comparison, the ²³⁴U/²³⁸U ratio found in urine from workers in volved with natural uranium or 4.5% enriched uranium is 1.0 and around 4.0 respectively. ²³⁰Th, ²²⁸Th and sometimes ²³²Th have also been detected. The total thorium activity varies from 0.137 to 5.6 mBq/24 h in urine and from 9 to 183 mBq/d in faeces. ²²⁸Th has generally been found in excess of ²³²Th. All these measurements were performed by alpha-spectrometry. The few ²²⁶Ra results have been measured using the Lucas or emanation method.     

Natural radioactivity around former uranium mine,Gabrovnica in Eastern Serbia

Gabrovnica near Kalna village was the first uranium mine established in Yugoslavia. In 1963, the Nuclear Energy Commission began operating the mine and mill. Between 1964 and 1966, the staff at Kalna extracted and produced an estimated 900 kg of UO₂ and 400 kg of uranium metal. The Kalna ore was of poor quality, containing very low uranium content, which required higher-cost mining and refining methods. That was the main reason for closing this mine. This paper presents results obtained by measuring the activity concentration of soil samples measured by gamma spectrometry and also indoor ²²²Rn activity concentrations in houses in the nearby village Kalna. There is a presence of elevated radioactivity levels in the most of the measured samples. The mine was never officially decommissioned. The results obtained might be useful for the future decommissioning procedure.     

Natural radioactivity levels in mineral,therapeutic and spring waters in Tunisia

Radioactivity measurements were carried out in 26 groundwater samples from Tunisia. Activity concentrations of uranium were studied by radiochemical separation procedures followed by alpha spectrometry and that for radium isotopes by gamma-ray spectrometry.The results show that, the concentrations in water samples range from 1.2 to 69 mBq/L.1, 1.3 to 153.4 mBq/L, 2.0 to 1630.0 mBq/L and 2.0 to 1032.0 mBq/L for ²³⁸U, ²³⁴U, ²²⁶Ra and ²²⁸Ra, respectively. The U and Ra activity concentrations are low and similar to those published for other regions in the world. The natural radioactivity levels in the investigated samples are generally increased from mineral waters through therapeutic to the spring waters.The results show that a correlation between total dissolved solids (TDS) values and the ²²⁶Ra concentrations was found to be high indicating that ²⁶⁶Ra has a high affinity towards the majority of mineral elements dissolved in these waters. High correlation coefficients were also observed between ²²⁶Ra content and chloride ions for Cl^?–Na⁺ water types. This can be explained by the fact that radium forms a complex with chloride and in this form is more soluble.The isotopic ratio of ²³⁴U/²³⁸U and ²²⁶Ra/²³⁴U varies in the range from 0.8 to 2.6 and 0.6 to 360.8, respectively, in all investigated waters, which means that there is no radioactive equilibrium between the two members of the ²³⁸U series. The fractionation of isotopes of a given element may occur because of preferential leaching of one, or by the direct action of recoil during radioactive decay.The annual effective doses due to ingestion of the mineral waters have been estimated to be well below the 0.1 mSv/y reference dose level.     

Natural and fallout radioactivity measurement in Indian soils

The paper presents the results of high resolution gamma-spectrometric measurements of ¹³⁷Cs, ⁴⁰K, ²³²Th and ²³⁸U in Indian soils collected from 24 different places from normal natural radiation background areas. The depth profile of ¹³⁷Cs was studied at sampling sites. The paper also presents ¹³⁷Cs levels in top soil at Mumbai during 1986 to 2000. The results in Mumbai soil indicate clearly the accumulation from fallout only on the top soil and seasonal peaking during the beginning of the monsoon season.     

Natural radioactivity measurements in the granite rock of quarry sites,Johor, Malaysia

This study was conducted to determine the concentration of natural radionuclides in the granite rocks of selected quarry sites in Johor state, Malaysia and their possible radiological effects. The activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K in the areas of study indicated varying values of ²³⁸U, ²³²Th and ⁴⁰K. The highest values of ²³⁸U and ²³²Th concentrations (67±1 and 85±2 Bq kg^?1, respectively) were observed at Kamad Quarry (IJM), whereas the highest value of ⁴⁰K concentration (722±18 Bq kg^?1) was detected in Kim Seng Quarry, while the values of activity concentration are lower in Hanson Quarry Products (Kulai) (25±0.5 for ²³⁸U, 24±0.5 for ²³²Th and 429±11 for ⁴⁰K). Overall, ⁴⁰K has the highest concentration in the granite rocks of the quarry sites, followed by ²³²Th and the least for ²³⁸U. The radium equivalent activity concentration was found in the range between 94 and 239 Bq kg^?1, the absorbed dose rate was found to be in the range between 47 and 112 nGy h^?1, and effective dose ranged from 58 to 137 μSv h^?1. Moreover, the internal and external hazard index values were given in results lower than unity.