Natural gamma-emiting radionuclides in Pakistani Portland cement

Assessment of Natural Radioactivity in Cements Used as Building Materials in Poland

It has been analyzed in this article the radioactivity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and radiological hazard parameters in different types of cements commonly used in Poland and available on the Polish market. The radiological hazard parameters are, in particular, absorbed gamma dose rate, annual effective dose, radium equivalent activity, the external hazard index, and the gamma and alpha indices. The radionuclide activities of the most important radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K have been determined by gamma-ray spectrometry with the use of two kinds of spectrometers of different operational parameters. One performed also measurements on 30-day and 45-day aged samples as to verify if there is a statistically significant difference in radioactivity concentration for shorter and longer aging time. The radioactivity concentrations in the cement samples ranged from 21.7-75.7 Bq·kg^-1 for ²²⁶Ra, 12.3-47.3 Bq·kg^-1 for ²³²Th to 123-430 Bq·kg^-1 for ⁴⁰K. The radiological parameters in cement samples were calculated as follows: mean radium equivalent activity Ra_eq = 127 Bq·kg^-1, mean absorbed gamma dose rate D = 115 nGy·h^-1, mean annual effective dose E = 570 µSv·y^-1, external hazard index H_ex = 0.32, internal hazard index H_in = 0.51, mean activity concentration index I_γ = 0.47 and mean alpha index I_α = 0.28. The results were compared with the reported data from other countries and the international standard values given by European Commission (EC) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR 2000). Finally, thorough statistical analysis has been performed.

An overview of radioactivity measurement studies in Pakistan

In our environment, various naturally occurring radionuclides are present (both underground and overground) in several places, which results in lifelong human exposure. The radiation dose received by human beings from the radiation emitted by these naturally occurring radionuclides is approximately 87%. Exposure to radiation poses radiological health hazards. To assess the human health hazards from radiation, the concentration of these naturally occurring radionuclides are measured in soil (used for cultivation), building materials (soil, bricks, sand, marble, etc.), water and dietary items, worldwide. The available literature revealed that numerous studies related to the subject have been carried out in Pakistan. Most of these studies measured the radioactivity concentrations of primordial [uranium (238U), thorium (232Th), radium (226Ra) and potassium (40K)] and anthropogenic [cesium (137Cs)] radionuclide in soil samples (used for cultivation), fertilizers, building materials (i.e. bricks, rocks, sand, soil, marble, etc.), as well as water and dietary items, using a sodium iodide detector or high purity germanium. An effort was made in 2008 to compile these studies as a review article. However, since then, considerable studies have been undertaken and reported in the literature. Therefore, the main objective of the present article is to provide a countrywide baseline data on radionuclide levels, by overviewing and compiling the relevant studies carried out in Pakistan.

Radiological safety assessment inside ancient Egyptian tombs in Saqqara

Many archaeological sites in Egypt are unique worldwide, such as ancient tombs and pyramids, because they document fundamental developments in human civilization that took place several thousands of years ago. For this reason, these sites are visited by numerous visitors every year. The present work is devoted to provide a pre-operational radiological baseline needed to quantify occupational radiation exposure at the famous Saqqara region in Cairo, Egypt. A hyperpure Ge detector has been used in the γ-ray spectrometric analysis while the (222)Rn concentration was measured using a portable radon monitor RTM 1688-2, SARAD. The mean specific activities of (226)Ra, (232)Th and (40)K in the samples collected from the interior walls of the Saqqara tombs were determined and found to show average values of 16, 8.5 and 45 Bq kg(-1), respectively. The concentration of radon was measured inside the tombs Serapeum, South tomb and the Zoser Pyramid (fifth level) and an associated average working level of 0.83 WL was obtained. In order to avoid the health hazards associated with the exposure to radon during the long period of work inside these tombs, proposed solutions are introduced.

Assessment of elemental and NROM/TENORM hazard potential from non-nuclear industries in North Sinai, Egypt

Non-nuclear industries use raw materials containing significant levels of naturally occurring radioactive material (NORM). The processing of these materials may expose workers engaged in or even people living near such sites to technologically enhanced naturally occurring radioactive material (TENORM) above the natural background. Inductively coupled plasma and gamma ray spectrometry have been used to determine major and trace elements and radionuclide concentrations in various samples, respectively, in order to investigate the environmental impact of coal mining and cement plant in North Sinai, Egypt. Generally, very little attention was directed to the large volumes of waste generated by either type of industrial activities. Different samples were analyzed including various raw materials, coal, charcoal, Portland and white cement, sludge, and wastes. Coal mine and cement plant workers dealing with waste and kaolin, respectively, are subjected to a relatively high annual effective dose. One of the important finding is the enhancement of all measured elements and radionuclides in the sludge found in coal mine. It may pose an environmental threat because of its large volume and its use as combustion material. The mine environment may have constituted Al, Fe, Cr, and V pollution source for the local area. Higher concentration of Al, Fe, Mn, B, Co, Cr, Mn, Ni, Sr, V, and TENORM were found in Portland cement and Zn in white cement. Coal has higher concentrations of Al, Fe, B, Co, Cr, and V as well as (226)Ra and (232)Th. The compiled results from the present study and different worldwide investigations demonstrate the obvious unrealistic ranges normally used for (226)Ra and (232)Th activity concentrations in coal and provided ranges for coal, Portland and white cement, gypsum, and limestone.

Soil-to-root vegetable transfer factors for (226)Ra, (232)Th, (40)K, and (88)Y in Malaysia

Soil-to-plant transfer factors (TFs) are of fundamental importance in assessing the environmental impact due to the presence of radioactivity in soil and agricultural crops. Tapioca and sweet potato, both root crops, are popular foodstuffs for a significant fraction of the Malaysian population, and result in intake of radionuclides. For the natural field conditions experienced in production of these foodstuffs, TFs and the annual effective dose were evaluated for the natural radionuclides (226)Ra, (232)Th, (40)K, and for the anthropogenic radionuclide (88)Y, the latter being a component of fallout. An experimental tapioca field was developed for study of the time dependence of plant uptake. For soil samples from all study locations other than the experimental field, it has been shown that these contain the artificial radionuclide (88)Y, although the uptake of (88)Y has only been observed in the roots of the plant Manihot esculenta (from which tapioca is derived) grown in mining soil. The estimated TFs for (226)Ra and (232)Th for tapioca and sweet potato are very much higher than that reported by the IAEA. For all study areas, the annual effective dose from ingestion of tapioca and sweet potato are estimated to be lower than the world average (290 μSv y(-1)).

Assessment of natural radioactivity levels of cements and cement composites in the Slovak Republic

The radionuclide activities of 226Ra, 232Th and 40K and radiological parameters (radium equivalent activity, gamma and alpha indices, the absorbed gamma dose rate and external and internal hazard indices) of cements and cement composites commonly used in the Slovak Republic have been studied in this paper. The cement samples of 8 types of cements from Slovak cement plants and five types of composites made from cement type CEM I were analyzed in the experiment. The radionuclide activities in the cements ranged from 8.58-19.1 Bq·kg(-1), 9.78-26.3 Bq·kg(-1) and 156.5-489.4 Bq·kg(-1) for 226Ra, 232Th and 40K, respectively. The radiological parameters in cement samples were calculated as follows: mean radium equivalent activity Ra(eq) = 67.87 Bq·kg(-1), gamma index Iγ = 0.256, alpha index Iα = 0.067, the absorbed gamma dose rate D = 60.76 nGy·h(-1), external hazard index H(ex) = 0.182 and internal hazard index H(in) was 0.218. The radionuclide activity in composites ranged from 6.84-10.8 Bq·kg(-1) for 226Ra, 13.1-20.5 Bq·kg(-1) for 232Th and 250.4-494.4 Bq·kg(-1) for 40K. The calculated radiological parameters of cements were lower than calculated radiological parameters of cement composites.

Estimation of radioactivity level and associated radiological hazards of limestone and gypsum used as raw building materials in Rawalpindi/Islamabad region of Pakistan

This study was undertaken to asses the radioactivity level of limestone and gypsum and its associated radiological hazard due to the presence of naturally occurring radioactive materials. Representative samples of limestone and gypsum were collected from cement factories located in the Rawalpindi/Islamabad region of Pakistan and were analysed by using an N-type high-purity germanium detector of 80 % relative efficiency. The average activity concentration of (40)K, (226)Ra and (232)Th were 60.22±3.47, 29.25±5.23 and 4.07±3.31 Bq kg(-1), respectively, in limestone and 70.86±4.1, 5.01±2.10 and 4.49±3.1 Bq kg(-1), respectively, in gypsum. The radiological hazard parameters radium equivalent activities, absorbed dose rate in air, external hazard index, internal hazard index, annual effective dose equivalent, gamma index and alpha index were computed. The results of the average activity concentrations of (40)K, (226)Ra and (232)Th and radiological hazard parameters were within the range of the reported average worldwide/United Nations Scientific Committee on the Effect of Atomic Radiation values. It is concluded that limestone and gypsum used in the Rawalpindi/Islamabad region does not pose any excessive radiological health hazard as a building raw materials and in industrial uses.

A review on natural background radiation

The world is naturally radioactive and approximately 82% of human-absorbed radiation doses, which are out of control, arise from natural sources such as cosmic, terrestrial, and exposure from inhalation or intake radiation sources. In recent years, several international studies have been carried out, which have reported different values regarding the effect of background radiation on human health. Gamma radiation emitted from natural sources (background radiation) is largely due to primordial radionuclides, mainly ²³²Th and ²³⁸U series, and their decay products, as well as ⁴⁰K, which exist at trace levels in the earth's crust. Their concentrations in soil, sands, and rocks depend on the local geology of each region in the world. Naturally occurring radioactive materials generally contain terrestrial-origin radionuclides, left over since the creation of the earth. In addition, the existence of some springs and quarries increases the dose rate of background radiation in some regions that are known as high level background radiation regions. The type of building materials used in houses can also affect the dose rate of background radiations. The present review article was carried out to consider all of the natural radiations, including cosmic, terrestrial, and food radiation.

Assessment of radiological hazards of naturally occurring radioactive materials in cement industry

A study on the radiological hazard in Portland cement due to the presence of naturally occurring radioactive materials is being carried out. The Portland cement manufactured in the Islamabad/Rawalpindi region of Pakistan, intermediate products (clinker) and the various raw materials which compose the product have been analysed for (226)Ra, (232)Th and (40)K using a gamma spectrometry system with a N-type high-purity germanium detector of 80 % relative efficiency. From the measured gamma ray spectra, specific activities were determined. The mean values of the total specific activity of (226)Ra, (232)Th and (40)K are 34.2±11.9, 29.1±3.6 and 295.1±66.9 Bq kg(-1), respectively in Portland cement, 28.4±8.7, 11.3±1.7 and 63.1±17.3 Bq kg(-1), respectively in lime stone, 8.2±1.9, 16.2±3.9 and 187.7±53.2 Bq kg(-1), respectively in gypsum, 34.7±13.1, 41.2±6.7 and 187.6±17.2 Bq kg(-1), respectively in clay, 41.1±11.8, 39.3±6.9 and 195.1±29.2 Bq kg(-1), respectively in latrite and 51.1±18.2, 23.2±1.2 and 258.4±15.3 Bq kg(-1), respectively in clinker. The radium equivalent activities (Ra(eq)), external hazard index (H(ex)), internal hazard index (H(in)), absorbed dose rate in air (D) and annual effective dose rate (E(eff)) were also determined. The measured activity concentrations for these radio nuclides and radiological indices were compared with the reported national and international data. All these measured values are comparable with the worldwide data reported in UNSCEAR publications.

Measurement of radionuclides and absorbed dose rates in soil samples of Peshawar, Pakistan, using gamma ray spectrometry

The analysis of gamma-emitting radionuclides in nature, i.e. (226)Ra, (232)Th, (40)K and (137)Cs, has been carried out in soil samples collected from Peshawar University Campus and surrounding areas using a high purity germanium detector coupled with a computer-based high-resolution multichannel analyser. The activity concentrations in soil ranged from 30.20±0.65 to 61.90±0.95, 50.10±0.54 to 102.80±1.04, 373.60±4.56 to 1082±11.38 and 9.50±0.11 to 46.60±0.42 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, with a mean value of 45±7.70, 67±12.50, 878±180 and 19±9.20 Bq kg(-1), respectively. The radium equivalent activity, internal and external hazard indices have mean values of 203.40±29.40 Bq kg(-1), 0.56 and 0.68, respectively. The mean values of outdoor and indoor absorbed dose rates in air and the annual effective dose equivalents were found to be 106.50 and 128 nGy h(-1) and 0.19 and 0.54 mSv y(-1), respectively. In the present study, (40)K was the major radionuclide present in soil samples. The presence of (137)Cs indicates that this area also received some fallout from the nuclear accident of the Chernobyl power plant in 1986. The activity concentrations of radionuclides found in soil samples during the current investigation were nominal. Therefore, they are not associated with any potential source of health hazard to the public.

Assessment of radiological hazards of clay bricks fabricated in the Punjab province of Pakistan

The Punjab is the most populous among the four provinces of Pakistan, which has around 72 million of people and 205 344 km(2) of land. The majority of the population of this province lives in houses made of clay bricks that contain variable amounts of naturally occurring radioactive material (NORM). The concentration level of NORM in clay bricks used to construct dwellings may pose health hazards to inhabitants if it exceeds the permissible limits. For radiological surveillance, activity concentrations of the primordial radionuclides (40)K, (226)Ra and (232)Th were measured in 140 brick samples collected from 35 districts of the Punjab province. A high-purity germanium gamma-ray detector coupled with a personal computer-based multichannel analyzer was employed for the measurement of activity concentrations of primordial radionuclides in the brick samples. The province-wide average activity concentrations and the range (given in parenthesis) of (40)K, (226)Ra and (232)Th were found to be 624 ± 133 (299-918), 35 ± 7 (21-47) and 42 ± 8 (22-58) Bq kg(-1), respectively. The values lie within the range of activity concentration values for clay bricks of some countries of Asia. Potential radiological constraint was checked in the form of hazard indices calculated from the measured activity concentrations; the indices were found to be less than their limiting values. Indoor external dose was calculated for a standard size room made of clay bricks, and the dose rate was 159 ± 30 (83-219) nGy h(-1). The average value of the dose rate is comparable to that of Asian countries and is about twice the worldwide average value. Annual effective dose E(ff) in the bricks-made room was calculated and the average value of the dose was 0.80 mSv y(-1), which is about twice the worldwide background value of 0.41 mSv y(-1).

Radioactivity levels of limestone and gypsum used as building raw materials in Turkey and estimation of exposure doses

The natural radionuclide contents of limestone and gypsum samples used as building raw materials in Turkey were measured by means of gamma spectrometer system with HPGe detector. The measured activity concentrations of (226)Ra, (232)Th and (40)K radionuclide were compared with the reported data from other countries. Radium equivalent activity and internal hazard index, absorbed gamma dose rate in indoor due to the external exposure and corresponding annual effective dose were determined to estimate the exposure risk arising due to the use of these raw materials. This study has shown that examined gypsum and limestone raw materials do not pose any excess radiological health problem and are safe for use in the construction of buildings.

Assessment of radiation hazards due to natural radioactivity in some building materials used in Egyptian dwellings

Different types of Egyptian building materials from various locations in Cairo and its suburbs have been analysed for natural radioactivity using gamma ray spectrometry. Concentrations of (226)Ra, (232)Th and (40)K were in the ranges of (12 +/- 2.8-65 +/- 6.5), (5 +/- 1.8-60 +/- 6.7) and (159 +/- 3.8-920 +/- 12.7 Bq kg(-1)), respectively. The minimum concentration of (226)Ra, (232)Th and (40)K was found in gravel samples, whereas the maximum in granite samples. The results are compared with the published data of other countries and with the world average limits. The radiological hazard parameters: radium equivalent activity, gamma index, alpha index, absorbed dose rate and the annual exposure rate, were determined to assess the radiation hazards associated with Egyptian buildings. All studied samples are lower than world average limits.

Natural radioactivity measurements in Pakistan--an overview

Humans have always been exposed throughout their period of existence to naturally occurring ionising radiation. Specifically, naturally occurring radionuclides are present in variable amounts in our environment. To assess radiological health hazards, naturally occurring radionuclides are being measured in soil, sand, marble, bricks etc throughout the world. In this regard, extensive data have been reported for Pakistan, which have been compiled and reviewed in this article. The majority of the reported articles are about monitoring of the radiological health hazards of naturally occurring radionuclides. In a few articles, use of the radionuclides has been reported for the exploration of uranium and thorium deposits. Most of the reported data have been obtained using a high purity germanium detector or a sodium iodide detector.

Assessment of natural radionuclide content of cements used in Nigeria

The activity concentrations of (226)Ra, (232)Th and (40)K in seven brands of Portland cement used in Nigeria have been determined using a gamma-ray spectrometer with a hyperpure germanium detector. A total of 22 samples were collected from suppliers. The mean activity concentrations varied between 19.2 and 85.1 Bq kg(-1), 12.9 and 31.7 Bq kg(-1), and 31.5 and 116 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively, which are lower than the world averages for building materials. The average values of (226)Ra, (232)Th and (40)K content of all the cement samples are 43.8, 21.5 and 71.7 Bq kg(-1), respectively. The results of the radium equivalent activity, external hazard index, gamma activity index and alpha index calculated were all within the recommended limits for safety, and compare well with results obtained in some other countries of the world.

Assessment of the natural radioactivity and radiological hazards in Turkish cement and its raw materials

The natural radioactivity due to presence of (226)Ra, (232)Th and (40)K radionuclides in raw materials, intermediate products (clinker) and end products (22 different cement types) was measured using a gamma-ray spectrometry with HPGe detector. The specific radioactivity of (226)Ra, (232)Th and (40)K in the analyzed cement samples ranged from 12.5+/-0.3 to 162.5+/-1.7Bqkg(-1) with a mean of 40.5+/-26.7Bqkg(-1), 6.7+/-0.3 to 124.9+/-2.5Bqkg(-1) with a mean of 26.1+/-18.9Bqkg(-1) and 64.4+/-2.3 to 679.3+/-18.2Bqkg(-1) with a mean of 267.1+/-102.4Bqkg(-1), respectively. The radium equivalent activity (Ra(eq)), the gamma-index, the emanation coefficient, the (222)Rn mass exhalation rate and the indoor absorbed dose rate were estimated for the radiation hazard of the natural radioactivity in all samples. The calculated Ra(eq) values of cement samples (37.2+/-8.7-331.1+/-15.5Bqkg(-1) with a mean of 98.3+/-53.8) are lower than the limit of 370Bqkg(-1) set for building materials. The Ra(eq) values were compared with the corresponding values for cement of different countries. The mean indoor absorbed dose rate is slightly higher than the population-weighted average of 84nGyh(-1).

Radiological significance of cement used in building construction in Turkey

The activity concentration of (226)Ra, (232)Th and (40)K in seven cement types from different factories and grinding plants were measured using a gamma ray spectrometry with HPGe detector. The average activity concentrations observed in the studied cement samples (all from 141 samples) were 40.0 +/- 27.1, 28.0 +/- 20.9 and 248.3 +/- 95.0 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The radium equivalent activity (Ra(eq)), the representative level index, the indoor absorbed dose rate and the corresponding annual effective dose were estimated for the potential radiological hazard of the cement. The Ra(eq) values were compared with the corresponding values for cement of different countries. The mean indoor absorbed dose rate (87.4 +/- 48.5 nGy h(-1)) is slightly higher than the population-weighted average of 84 nGy h(-1), whereas the corresponding effective dose rate (0.4 +/- 0.2 mSv y(-1)) is lower than the dose criterion of 1 mSv y(-1). The obtained results indicate no significant radiological hazards arise from using Turkish cement in building construction.

Radionuclide content of local and imported cements used in Egypt

The activity concentrations of natural and artificial gamma-ray emitting radionuclides in local and imported cement have been investigated during the period from 2000 to 2003 using a 50% HPGe gamma-spectroscopy system. The total numbers of local and imported samples were 29 and 8, respectively. The results showed a low activity concentration of (137)Cs in both 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 activity concentrations of (226)Ra, (232)Th and (40)K in local cement were 33 +/- 17, 14 +/- 2.4 and 45 +/- 26 Bq kg(-1), respectively, whereas those in imported cement were 27 +/- 7, 8 +/- 7 and 134 +/- 22 Bq kg(-1), respectively. The results showed that blast furnace slag cement contains the highest level of natural radioactivity, whereas white cement contains the lowest levels. The measured activity concentrations of the detected radionuclides were compared with other measurements carried out in Egypt and elsewhere. Radium-equivalent activities were also calculated to assess the radiation hazards arising from using such material in the construction of dwellings. Generally, the radium-equivalents of the analysed samples were smaller than the guideline limit of 370 Bq kg(-1).

Radioactive analysis of cement and its products collected from Shaanxi, China

This note presents a study of 226Ra, 232Th, and 40K in cement and its products manufactured in some areas of Shaanxi, China. The concentrations of 226Ra, 232Th, and 40K were 46.2, 28.4, and 137.4 Bq kg(-1), respectively, for cement brick; and 64.7, 48.7, and 161.3 Bq kg(-1), respectively, for cement plaster. The concentration of 226Ra, 232Th, and 40K in cement ranges from 34.7 to 68.3 Bq kg(-1) with a mean value of 56.5 Bq kg(-1), 18.5 to 51.7 Bq kg(-1) with a mean value of 36.5 Bq kg(-1), and 126.8 to 224.6 Bq kg(-1) with a mean value of 173.2 Bq kg(-1), respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries. The radium equivalent activities (Raeq), external hazard index (Hex) and internal hazard index (Hin) associated with the radionuclides were calculated. The Raeq values of cement and cement products are lower than the limit of 370 Bq kg(-1), equivalent to a gamma dose of 1.5 mSv y(-1). The values of Hex and Hin are less than unity.