226Ra, 228Ra and 228Ra/226Ra in surface marine sediment of Malaysia

Surface sediment samples were collected at the West (east coast and west coast of Peninsular Malaysia) and East (Sabah and Sarawak) Malaysia in several expeditions within August 2003 until June 2008 for determining the level of natural radium isotopes. Activity concentrations of ²²⁶Ra and ²²⁸Ra in surface marine sediment at 176 sampling stations were measured. The activity concentrations of both radionuclides in Malaysia (East and West Malaysia) display varied with the range from 9 to 158 Bq/kg dry wt. and 13 to 104 Bq/kg dry wt., respectively. Meanwhile, the ratio distributions of ²²⁸Ra/²²⁶Ra were ranged from 0.62 to 3.75. This indicated that the ratios were slightly high at west coast of Peninsular Malaysia compared to other regions (east coast of Peninsular Malaysia, Sabah and Sarawak). The variation of activity concentrations of ²²⁶Ra and ²²⁸Ra and its ratios were also supported by the statistical analyses of one-way ANOVA and t test at 95 % confidence level, whereby there were proved that the measured values were different between the regions. These different were strictly related to their half-life, potential input sources (included their parents, ²³⁸U and ²³²Th), parent’s characteristic, the geological setting/formation of the study area, environment origin and behavior.     

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 and radiation hazards in some building materials used in Isparta,Turkey

The activity concentrations of uranium, thorium and potassium can vary from material to material and it should be measured as the radiation is hazardous for human health. Thus first studies have been planned to obtain radioactivity of building material used in the Isparta region of Turkey. The radioactivity of some building materials used in this region has been measured using a γ-ray spectrometry, which contains a NaI(Tl) detector connected to MCA. The specific activity for ²²⁶Ra, ²³²Th and ⁴⁰K, from the selected building materials, were in the range 17.91–58.88, 6.77–19.49 and 65.72–248.76 Bq/kg, respectively. Absorbed dose rate in air (D), annual effective dose (AED), radium equivalent activities (Ra_eq), and external hazard index (H_ex) associated with the natural radionuclide are calculated to assess the radiation hazard of the natural radioactivity in the building materials. It was found that none of the results exceeds the recommended limit value.     

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.     

Measurement of natural radioactivity and radiation hazards for some natural and artificial building materials available in Romania

As building materials are known to be the second source regarding high radon concentrations, it is very important to determine the amounts of natural radionuclides from every building material in use. In the present study the most frequently used Romanian natural (sand, gypsum, limestone) and artificial (portland cement, lime, clinker, electrofilter powder, fly ash, cement-lime plaster mortar, cement plaster mortar) building materials were analyzed. The absorbed dose rate and the annual effective dose equivalent rate for people living in dwelling buildings made of these building materials under investigation were also calculated. The analysis was performed with gamma-ray spectrometry, with two hyper-pure germanium detectors. The activity concentrations of natural radionuclides were in the ranges: 5.2–511.8 Bq kg^?1 for ²²⁶Ra; 0.6–92.6 Bq kg^?1 for ²³²Th and <1–1,720.7 Bq kg^?1 for ⁴⁰K, respectively. The radium equivalent activity in the fifty-one (51) samples varied from 9 to 603 Bq kg^?1. By calculating all the radioactivity indices (Ra_eq, H _ext, I _α, I _yr) it was found that all the building materials under investigation can be used to erect dwelling buildings. Except for sample SA6, SA7 and SA11 among the natural building materials and sample SG1, SG2, FAH1, CLM1, CM1 among the artificial building materials that are considered hazardous materials when are used in large quantities.     

Radiological hazard and radiogenic heat production in some building materials in upper Egypt</p> </p>

Summary Samples of limestone, sand, marble, clay brick, red brick, gypsum, Portland cement and white cement collected from upper Egypt used in building manufacturing have been analyzed for the natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K usingg-ray spectrometry. The specific concentrations for ²²⁶Ra, ²³²Th and ⁴⁰K, ranged from 20-88, 13-115 and 54-304 Bq/kg, respectively. The average specific activities of these radionuclides were compared. Higher values of ²²⁶Ra and ²³²Th could be noticed in marble while that of ⁴⁰K was in red bricks. Radium equivalent activities, dose rate and the annual gonadal dose equivalents AGDE were calculated for the measured samples to assess the radiation hazard arising from using those materials in the construction of dwellings. The radioactive heat production values of the selected materials have also been determined. They vary from a minimum of 0.41 for white cement to a maximum of 5.52mW/m³ for marble samples. The calculated heat-production values are quite similar to those estimated in Corsica.</p> </p>     

Concentration of radionuclides in building and ceramic materials of Bangladesh and evaluation of radiation hazard

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).     

The radioactivity of building materials

Summary Radiation exposure of the population can be increased appreciably by the use of building materials containing above-normal levels of naturally occurring radionuclides of terrestrial origin, as high as 1600 Bq^. kg^-1for ⁴⁰K in granites, 700 Bq^. kg^-1for ²²⁶Ra in phosphogypsum and 360 Bq^. kg^-1for ²³²Th in granites. In a 25-year survey including more than two hundreds of different materials were investigated. Of the materials normally used in the building industry, i.e., red clay bricks, cement of Portland Types I and II, concretes, gravels and sand, contain regular levels of the primordial radionuclides. The adsorbed dose rate in indoor air, in general, does not exceed the dose criterion of 80 nGy^. h^-1or 0.3 mSv^. y^-1for the effective dose. Granites and phosphogypsum are the highly radioactive materials for which the absorbed dose rate in indoor air becomes up to five times higher than the dose criterion. It is recommended to avoid the use of those materials without radioactivity control.     

Specific activities and radioactive contour maps of natural and anthropogenic radionuclides in beach sand samples (Patong, Kamala, Kata, Karon and Nai Yang) after tsunami disaster in Phuket province, Thailand

Specific activities of natural (⁴⁰K, ²²⁶Ra and ²³²Th) and anthropogenic (¹³⁷Cs) radionuclides in 155 beach sand samples collected from Patong, Kamala, Kata, Karon and Nai Yang beaches, which were affected by the 2004 tsunami disaster, in Phuket province, Thailand, have been studied and measured. Experimental results were obtained by using a high-purity germanium detector and gamma spectrometry analysis system. Gamma ray from radioactive standard sources Cesium-137 (¹³⁷Cs), Cobalt-60 (⁶⁰Co) and Barium-133 (¹³³Ba) were used to calibrate the measurement system. KCl, two well-known (IAEA/RGU-1 and IAEA/RGTh-1) and IAEA/SL-2 reference materials obtained from the International Atomic Energy Agency were used to analyze and compute the ⁴⁰K, ²²⁶Ra,²³²Th and ¹³⁷Cs specific activities in samples from five beaches. The measuring time of each sample is 10,800 s. It was found that the average specific activity of ⁴⁰K in these areas (2459.14 ± 171.71 Bq/kg) was rather high. Furthermore, the results were also used to evaluate the absorbed dose rates in air (D), the radium equivalent (Ra_eq), the external hazard index (H_ex) and the annual effective dose rate (AED_out) in all beach areas. Moreover, experimental results were compared with the Office of Atoms for Peace research data, Thailand as well as with global radioactivity measurements and evaluations. All of the calculated values (⁴⁰K, ²²⁶Ra, ²³²Th and ¹³⁷Cs) were also compared with the recommended values which were proposed by the Organization for Economic Cooperation and Development (Exposure to radiation from natural radioactivity in building materials, 1979) and United Nations Scientific Committee on the Effects of Atomic Radiation (Sources, effects and risk of ionizing radiation, 1988; Exposure from natural sources of radiation, 1993; Sources, effects and risk of ionizing radiation, 2000). The data can be also used to create the radioactive contour maps of the investigated area.     

Levels and effects of natural radionuclides in soil samples of Garhwal Himalaya

Distribution of natural radionuclide gives significant parameter to assess the presence of gamma radioactivity and its radiological effect in our environment. Natural radionuclides are present in the form of ²²⁶Ra, ²³²Th and ⁴⁰K in soil, rocks, water, air, and building materials. Distribution of natural radionuclides depends on the type of minerals present in the soil and rocks. For this purpose gamma spectrometer is used as tool for finding the concentration of these radionuclides. The activity concentration of naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in these soil samples were found to vary from of 8 ± 1 Bq/kg to 50 ± 10 Bq/kg with an average 20 Bq/kg, 7 ± 1–88 ± 16 Bq/kg with an Average 26 Bq/kg and 115 ± 18–885 ± 132 Bq/kg with an average 329 Bq/kg, respectively. In this paper, we are presenting the radiological effect due to distribution of natural radionuclide present in soil of Garhwal Himalaya.     

NORM activity concentration in sediment cores from the Peninsular Malaysia East Coast Exclusive Economic Zone

Study for distribution of Naturally Occurring Radioactive Materials (NORM) i.e. ²²⁶Ra, ²²⁸Ra and ⁴⁰K in the east coast of Peninsular Malaysia Exclusive Economic Zone (EEZ) was carried out as part of the national marine environment project. Sixteen marine sediment cores from selected locations within the EEZ were collected for determination of NORM activity concentrations using high-purity germanium (HPGe) gamma spectrometer. From the measurement, the activity concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K is ranged from 16 ± 4 Bq/kg to 46 ± 6 Bq/kg (total mean 30), 28 ± 7 Bq/kg to 87 ± 11 Bq/kg (total mean 56) and 171 ± 33 Bq/kg to 690 ± 89 Bq/kg (total mean 420), dry wt., respectively. The activity concentrations of radionuclides in most of the core were quite uniform suggesting that there were thorough vertical mixed of sediment throughout the core. The results obtained were also in good agreement with those previous reported from other countries in the region and therefore can be used to enhance present radioactivity database. The calculated external hazard values were ranged from 0.25 to 0.51 with the mean of 0.38 (less than unity) showed little risk of external hazard to the workers handling the sediments and it was likely low level of the mainland natural gamma-radiation in the east coast of Peninsular Malaysia.     

Measurement of naturally occurring radioactive materials (NORM) in beach sand minerals using HPGe based gamma-ray spectrometry

This paper discusses the measurement of naturally occurring radioactivity materials (NORM) in beach sand minerals using high resolution gamma spectrometry. In India, the beach sand minerals of economic interest from coastal Kerala, Tamil Nadu and Orissa are enriched with NORM due to the occurrence of monazite deposits and heavy minerals such as zircon, ilmenite, magnetite, garnet, rutile etc. Since many of these ores are rich in ²³²Th and other radio elements, certification of radioactivity levels has become mandatory in recent years. The average activity concentrations of ²²⁶Ra in zircon, rutile and garnet were 3,531, 1,134 and 17 Bq kg^?1, respectively. The average activity concentration of ²³²Th observed in zircon, rutile and garnet were 618, 454 and 64 Bq kg^?1, respectively. Concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K in ilmenite ore ranged from 17.6–444 Bq kg^?1, 80.4–1971 Bq kg^?1 and ≤5.5–25.0 Bq kg^?1, respectively.     

Concentration of natural radionuclides in various types of building materials in Slovakia

The building materials and products whose content of natural radionuclides are contributors to the radiation exposure of the population. In this study several types of building materials used for construction of living buildings in Slovakia were examined. The concentrations of natural radionuclides (²²⁶Ra,²³²Th and⁴⁰K) were determined by -ray spectrometry with an HPGe detector. In the second part of the work, sixty samples of building products (panel), used for dwelling construction in several towns in Slovakia, were analysed. The concentration of natural radionuclides and the radium equivalent activity content in the inner-and outerside of the wall were estimated. The results were used for the calculation of the annual mean effective photon dose rates, by the model and calculation procedure of KRISIUK and KARPOV.     

Assessment of natural uranium and 226Ra concentration in ground water around the uranium mine at Narwapahar, Jharkhand, India and its radiological significance

A brief study on dissolved radionuclides in aquatic environment, especially in ground water, constitutes the key aspect for assessment and control of natural exposure. In the present study the distribution of natural uranium and ²²⁶Ra concentration were measured in ground water samples collected within a 10 km radius around the Narwapahar uranium mine in the Singhbhum thrust belt of Jharkhand, India in 2007–2008. The natural uranium content in the ground water samples in this region was found to vary from 0.1 to 3.75 μg L^?1 with an average of 0.87 ± 0.73 μg L^?1 and ²²⁶Ra concentration was found to vary from 5.2 to 38.1 mBq L^?1 with an average of 13.73 ± 7.34 mBq L^?1. The mean annual ingestion dose due to intake of natural uranium and ²²⁶Ra through drinking water pathway to male and female adults population was estimated to be 6.55 and 4.78 μSv y^?1, respectively, which constitutes merely a small fraction of the reference dose level of 100 μSv y^?1 as recommended by WHO.     

Natural radioactivity of geothermal water in Beijing,China

In this work, we collected 101 geothermal water samples to investigate comprehensively the radioactivity of geothermal water in Beijing. The concentrations of gross beta, ²²⁶Ra and ²²²Rn were measured and the obtained values were in the range of 0.032–7.060, 0.023–0.363 and 0.470–29.700 Bq/L, respectively. The samples with higher concentration of ²²²Rn were found to be located near large faults. The effective dose of ²²²Rn in the air for three cases were calculated to be greater than radiation dose limit of 1 mSv/a.     

Measurement of natural radioactivity and radiation hazard assessment in the soil samples of Visakhapatnam,Andhra Pradesh,India

The present work aims to measure and estimate radioactivity and hazardous radiation indices of the soil. Soil samples were collected from various locations in the Visakhapatnam district in Andhra Pradesh, India. The measurement of specific activity of ²²⁶Ra, ²³²Th, and ⁴⁰K radionuclides is carried out with the help of HP-Ge based gamma spectrometer system. Activity concentration of radionuclides in the samples ²²⁶Ra, ²³²Th and ⁴⁰K ranged from 20 ± 2 to 91 ± 2 Bq.kg^-1, 45 ± 3 to 365 ± 3 Bq.kg^-1, and 400 ± 9 to 607 ± 8 Bq.kg^-1, and the respective mean values are 53.36 Bq.kg^-1, 203.74 Bq.kg^-1 and 479.19 Bq.kg^-1. The measured mean value of the absorbed dose rate is 171.41 nGy.h^-1, which was beyond the worldwide mean outdoor value of 60 nGy.h^-1. Thus, the annual effective dose estimated from the above value is 1.04 mSv.y^-1. The correlation was done among the measured ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations. The estimated radium equivalent dose is 381.60Bq.kg^-1. The estimated health hazard index and annual effective dose rates of dwellers of Visakhapatnam were studied and compared to Indian average values. The study will help to generate the baseline data for assessing hazard indices to the public and geological mapping of natural radiation in India.     

Natural radioactivity in sand samples collected along the bank of river Indus in the area spanning over Gilgit to Lowarian, Pakistan: assessment of its radiological hazards

Sand is extensively used in construction of buildings. The presence of natural radioactivity in it results in internal and external exposure to the general public. Therefore, it is desirable to determine the concentration of naturally occurring radio-nuclides, namely ²³²Th, ²²⁶Ra and ⁴⁰K in sand. In this regard, in continuation of our earlier studies, 42 sand samples were collected from fourteen different locations along the banks of river Indus from Gilgit to Lowarian in the northern part of Pakistan covering an area of ~500 km. In order to measure the specific activities in these samples, a P-type coaxial high purity germanium based gamma-ray spectrometer was used. Average values of the measured activities of ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 45.6 ± 3, 74.73 ± 3 and 339.8 ± 3.6 Bq kg^?1, respectively which results in an average absorbed dose rate 83.54 nGy h^?1. From the measured activities, average radium equivalent activity was found to be 178.59 Bq kg^?1. External and internal hazard indices were also calculated and found to be 0.48 and 0.61, respectively. Average effective dose expected to be received due to the gamma rays was 0.26 mSv y^?1. Measured natural radioactivity, hazard indices and effective doses received by the population were found to be within the recommended limits.     

Measurement of natural radioactivity in soil from Peshawar basin of Pakistan

Natural radioactivity in the environment may change with time due to human activities, chemical and biological changes. From the view of radiation risk to population, the knowledge of natural radioactivity levels and the measurement of collective radiation dose received by the population is very vital. Radiological constraints on soil of thickly populated Peshawar basin in northern Pakistan were assessed through radiometric assay. Soil samples collected from different locations of four districts of this basin were analysed using an HPGe gamma spectrometer. Activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th in these samples was 648 ± 121 (421–996), 45 ± 7 (32–60) and 59 ± 7 (46–72) Bq kg^?1, respectively that followed lognormal distribution. The average concentrations of primordial radionuclides were found to be higher than that reported for the worldwide soil. Radium equivalent activity and gamma index derived from these activity concentrations were lesser than their respective limits. The average absorbed dose rate and the annual effective dose for both indoor and outdoor cases were found to be higher than the values given in the UNSCEAR 2000 report. The results of the present study were compared with those for other locations of Pakistan along with that for the world. The radiological impact of the measured data was evaluated using hazard assessment models. A thoughtful discussion of the above mentioned evaluation is also given.     

Radiological impact from natural radionuclide activity concentrations in soil and vegetables at former tin mining area and non-mining area in Peninsular Malaysia

The radionuclide concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were measured in eleven different types of vegetables from nine sample locations in Peninsular Malaysia by using gamma spectrometry with high purity germanium detector. Radiological impact and cancer risk arising from the ingestion of vegetables was also determined in this study. The annual ingestion dose of vegetables from former tin mining area and non-mining area were found to be 0.64 and 0.61 µSv y^?1. Corresponding cancer risk estimated for adults were 2.24 × 10^?6 and 2.15 × 10^?6 for former tin mining area and non-mining area, respectively. Both of them were lower than predicted value recommended at international level by ICRP, 3.5 × 10^?3. The present study concludes that vegetables planted at both areas would not pose any significant radiological impact to the population, despite the higher concentration of radionuclide in soil. External hazard indices from soil in this study are less than one. Thus, the soils are suitable for use in agriculture.     

Natural radioactivity and indoor radiation measurements in buildings and building materials in Gobichettipalayam town

Samples of natural and manufactured building materials used by the people of Gobichettipalayam town have been analyzed for ²²⁶Ra, ²³²Th and ⁴⁰K using gamma-ray spectrometry. Radium equivalent activity of the materials has been measured using the formula given by OECD and the geometric mean value of sand, clay and cements are found to be 53.53 Bq·kg⁻¹, 89.09 Bq·kg⁻¹ and 72.25 Bq·kg⁻¹, respectively. The radium equivalent activities obtained in the building materials are all well below the acceptable limit. The indoor gamma-dose has been measured using thermoluminescence dosimeters and it was found in the range of 1051.2–3946.0 μGy/year. The annual effective indoor gamma radiation dose to the people of Gobichettipalayam town has been found to be 0.8 mSv/y.