Natural Radionuclides Research Articles

Natural radioactivity assessment of coal combustion residues produced in Indian thermal power plants using high-purity germanium detector

Abstract Huge amount of coal combustion residue (CCR) is being generated in India every year. Since coal contains some natural radionuclides, the CCR may contribute to the enhanced natural radiation background. Hence, it is important to monitor the natural radioactivity levels in Indian CCR samples. The present study aims to estimate the natural radioactivity levels in CCRs produced in Indian thermal power plants. Accordingly, six CCR samples from different thermal power plants were collected and packed to achieve secular equilibrium among daughter products of 226Ra. The samples were counted for activity of gamma radionuclides using high purity germanium detector based high resolution gamma spectrometer. Results show that 40K is the most abundant among analyzed radionuclides, and the lowest was observed for 226Ra. Secular equilibrium was observed between 228Ra and 228Th, whereas no equilibrium was observed between 226Ra and 238U. The activity concentration for 226Ra and its daughter products (214Pb and 214Bi) was found to be similar in CCR sample before and after equilibrium, indicating that progenies are in secular equilibrium in CCR. The X ray diffraction analysis of CCR indicates the presence of aluminosilicate as major fraction, which has potential of trapping of 226Ra and daughter products. The values observed are very low and similar to those observed in naturally occurring radioactive materials such as coal, soil, and sediment, hence are not of radiological concern with respect to human/environment.

Pollution distribution caused by natural and artificial radionuclide in water and sediments of the International Miankaleh Lagoon in north of Iran

Pollution distribution caused by natural and artificial radionuclide in water and sediments of the International Miankaleh Lagoon in north of Iran

Радиоэкологическая обстановка в районе вводимого в эксплуатацию рудника № 6 пао «Приаргунское горно-химическое производственное объединение»

Purpose: Study of the radioecological situation around mine No. 6 of PJSC ‘Priargunsky Industrial Mining and Chemical Association’ named after E.P. Slavskiy" before commissioning. Material and Methods: During the radiation survey, to measure the ambient dose equivalent rate, the pedestrian gamma survey method was used using the portable spectrometric complex MKS-01A ‘Multirad-M’ (Russia) and the dosimeter-radiometer MKS-AT6101s (Belarus). To study the specific activity of radionuclides in the soil, samples were taken in accordance with GOST 17.4.3.01-2017. The activity of gamma-emitting radionuclides was measured on a stationary gamma spectrometer manufactured by Canberra (USA). The activity of 210Po and 210Pb was measured on the radiometric system UMF-2000 (Russia) after their radiochemical extraction from samples. Dose assessment of exposure to biological objects was made using dose coefficients established in ICRP Publication 136, considering recommendations R52.18.820-2015. Results: The results of the study showed that the ambient dose equivalent rate of gamma radiation varied in a wide range from 0.1 to 4.9 µSv/h. The average value in the background areas is 0.14±0.02 µSv/h. The specific activity of natural radionuclides outside the rock dumps, except for 40K, in some areas exceeds the background values up to 10 times. The ecological risk for the considered terrestrial biological objects (grass, shrub, soil worm and mouse-like rodents) does not exceed 10‒2. Conclusion: There are areas on the territory with traces of anthropogenic activity, which led to man-made radiation contamination. The highest levels of ambient dose equivalent of gamma radiation occur near rock dumps. The rest of the territory has local areas with radioactive contamination. Doses of exposure to biological objects don’t have a significant effect on the incidence, reproduction, and life expectancy of terrestrial biological objects.

Comprehensive radiation and ecological study of the city of Tyumen

The article presents the results of comprehensive radiation ecological studies of the territory of Tyumen which consisted of the study of the content of natural (40K, 226Ra, 232Th) and man-made (137Cs, 90Sr) radionuclides in the surface layer of soils, the measurement of radon flux density from the ground and the equivalent dose rate of gamma radiation. The content of natural and man-made radionuclides, radon flux density from the soil surface, equivalent dose rate of gamma-radiation do not exceed the current standards of radiation safety. The data obtained can be used for scientific as well as production purposes in the field of radiation and environmental monitoring of urbanized areas

Assessment of radiological hazards due to ingestion of natural radionuclides in cooking oil samples

Assessment of radiological hazards due to ingestion of natural radionuclides in cooking oil samples

Evaluation of Radioactivity in Soil Sample from Al-Hadbaa Cement Plant in Nineveh Governorate, Iraq

The fundamental goal of this study is to measure the level of radioactivity in the soil of the area around Al-Hadbaa cement plant, also to evaluate the radiological hazard of radionuclide, gamma-spectroscopy with an HPGe detector with the crystal diameter of 70.6 mm and length of 70 mm has been used to estimate the specific activity of natural radionuclides 226Ra, 232Th, 40K, and artificial radionuclides 137Cs in the fifteen soil samples collected. The results show that the average concentration of specific activity of 226Ra, 232Th, 40K, and 137Cs was 11.17 ± 1.69, 13.38 ± 0.72, 158.36 ± 5.35 Bq/kg, and 1.52 ± 0.19 Bq/kg, respectively. The average specific activity of these radionuclides is discovered to be lower than the global average which is 33 Bq/kg for 226Ra, 30 Bq/kg for 232Th, and 400 Bq/kg for 40K. Radiological hazard indices are determined according to the activity concentration of the radionuclides in the area under study. The outcome of the radiological hazard index is within the globally recognized limit proposed by UNSCEAR which is 1000 μSv/y for annual effective dose and 290 × 10-6 for cancer risk, so it is possible to conclude that there are no radiological hazards as a result of radiation exposure to the workers working in the cement plant as well as the organisms living in the region.

Radioactivity of anthropogenic and natural radionuclides in marine sediments of the Chaun Bay, East Siberian Sea

Natural radioactive isotopes serve as a useful proxy of geological and geochemical processes in marine environment, while radiocesium serves as an indicator of man-made contamination. Monitoring of natural and anthropogenic radioactivity under conditions of the climate changes in the Arctic region is of high importance in investigations of this natural system. For the first time, we report the data on spatial distribution of natural (232Th, 226Ra, 40K) and anthropogenic (137Cs) radionuclide activities in the marine sediments from Chaun Bay (East Siberian Sea). The measured activity concentrations varied in the range 23.7–77.9 (mean 39.2) Bq kg−1 for 232Th, 16.5–39.3 (mean 26.6) Bq kg−1 for 226Ra, 535–991 (mean 726) Bq kg−1 for 40K, and 0.5–4.7 (mean 2.0) Bq kg−1 for 137Cs. The radiocesium level in the sediments showed no local sources of anthropogenic pollution in the Chaun Bay, while the average activity concentration of 40K was 1.8 times higher than worldwide.

Uranium isotopes content in the certain types of foodstuffs. Optimization of the analytical method

An article contents the results of investigation of natural uranium isotopes content in the certain types of foodstuffs sampled in the kitchen gardens located in Leningrad region and bought in the trade network of Saint-Petersburg. More suitable and simple for realization than existing method is given for uranium isotopes (238U, 234U, 235U) content investigation in the foodstuffs from a sample with not more than 1,0 kg weight with minimal detectable activity not more than 0,02 Bq. Radiochemical investigations were carried out in 2018-2020. Estimation of potential average annual population internal exposure dose (Eint) have been carried out due to 238U and 234U content in the bread foodstuffs, black leaf tea, spicy herbs and salad greenery consumed by the local population. It is demonstrated that population internal exposure dose from uranium isotopes in the investigated types of foodstuffs could be about 0,0000022 mSv/ year. Estimated dose value is only small part of population internal exposure dose from uranium and even more so from total composition of natural radionuclides in the foodstuffs. At the same time toxic effect from soluble uranium as a chemical element prevails over its radiation effect.

Factors Contributing to Accumulation of 210Po in Freshwater Fishes in Dong Thai Lake, Vietnam and Radiological Hazard Assessment.

210Po (polonium), one of the most toxic naturally occurring radionuclides, is well-known as a common natural radionuclide in fish species. Human consumption of 210Po-contaminated fish could result in a significant internal dose. This study determined by alpha spectrometry the 210Po activity in sixteen selected fish species with different living behaviors (pelagic, demersal), trophic positions (herbivores, carnivores, omnivorous), and masses in Dong Thai Lake, Hanoi, Vietnam. The min, max, and average of the 210Po concentration of sixteen fish species were 0.80 ± 0.44, 12.7 ± 0.20, and 3.54 ± 0.31Bq kg-1, respectively. Regarding the different living behaviors, trophic positions, and masses, the results showed trending of 210Popelagic > 210Podemersal; 210Poherbivores < 210Pocarnivores < 210Poomnivorous and 210Po<0.2kg > 210Po0.2-1kg > 210Po>1kg, respectively. The 210Po concentrations in muscle tissue were greater in fish species with a small mass, omnivorous trophic position, and pelagic living behavior relative to demersal fish with a larger mass that were herbivores or carnivores. In addition, the results showed an uneven distribution of 210Po activities in atmospheric aerosols, terrestrial soils, surface waters, and lake sediments in the study area. The primary source of 210Po could be supplied from atmospheric aerosols and/or terrestrial soils in the study area. The 210Po annual effective dose for adults due to fish consumption has been calculated with a range from 20 to 400µSv y-1 and 111µSv. y-1 on average, and it is far below the allowable limits of 1000µSv y-1.

Gamma Spectrometry Analysis of Natural and Man-Made Radioactivity and Assessment of Radiological Risk in Soils Around Steel Industry

"In this paper low background high-resolution gamma spectrometry was used for the determination of the activity concentrations of the natural and man-made radionuclides in topsoil samples collected in the vicinity of a large steel plant in Galati, Romania. Their values (mean ± standard deviation) for 238U, 226Ra, 232Th, 235U, 210Pb, 40K and 137Cs were: 38.1 ± 6.2; 35.9 ± 5.4; 35.5 ± 3.0; 1.8 ± 0.4; 47.3 ± 8.6; 504.5 ± 38.9 and 7.2 ± 4.7 Bq·kg–1, respectively. 60Co and 241Am had activities below the detection limit: 0.6–1.3 and 2.2–4.7 Bq·kg–1, respectively. The results indicate inputs of natural radionuclides in the sites close to the slag dump, raw materials transportation facility, ore and coal processing factories, blast furnaces, and iron scrap deposit. The evaluation of the associated radiological impact was performed based on selected hazard parameters: absorbed gamma dose rate, total external gamma dose rate, radium equivalent activity index, external hazard index, representative level index, annual effective dose, excess lifetime cancer risk, and annual gonadal dose."

Assessments of annual effective doses for population and estimation of environmental risk in the vicinity of coal-fired power plant Kakanj, Bosnia and Herzegovina

The paper describes radioactivity monitoring and radiological risk assessment procedures for the population and the environment in three villages located around the coal-fired power plant. The dose assessments were performed after long-term radioactivity monitoring that was carried out in the production process and in the vicinity of the coal-fired power plant Kakanj, Bosnia and Herzegovina.The estimated annual effective doses for the population living in the observed villages were in the range of 1.89–2.13 mSv. The most significant contributions were delivered from ingestion of food and water (0.55–0.63 mSv y−1); external exposure from building materials (0.44–0.62 mSv y−1) and inhalation of radon (222Rn) progeny (0.29–0.62 mSv y−1).The inhalation doses from flying radionuclide particles were not significant with values in the range of 0.0056–0.0062 mSv y−1 for inhalation of 235U, 238U, 226Ra, and 232Th. External terrestrial doses were in the range of average world values (0.070–0.094 mSv y−1).Environmental risk was estimated using the ERICA tool which did not highlight any threatened species. A conservative approach with a lower dose screening value (10 nGy h−1) indicated the risk for lichens and bryophytes as terrestrial organisms with high accumulation capacity for natural radionuclides.

Natural radionuclides behaviour in drinking groundwaters from Castilla y León (Spain); radiological implications

Since the coming into force of the European Council Directive 51/2013 EURATOM and its transposition into the Spanish legislation, the presence of radioactive substances in drinking waters must be kept under surveillance to ensure that the health protection requirements are met. Driven by this regulatory framework, in an attempt to know the starting point from which to design surveillance plans, the groundwaters intended for human consumption of Castilla y León (Spain) have been radiologically characterised by using both low-level γ-ray and α-particle spectrometry to determine the activity concentration of the natural radionuclides needed to account for the indicative dose estimation. This extensive research has comprised the radiological characterisation of more than 400 drinking water samples from one of the European Union's largest regions. Furthermore, the gross α and gross β activities have been analysed. Results showed a high geographical variability that can be related to the hydrogeological formations where the groundwaters come from. The uranium isotopes, 234U and 238U, are the main radionuclides present in the analysed drinking waters reaching values up to 2000 mBq/L, in the southwestern and western of Castilla y León, where U-rich minerals are part of the host rock. High 210Pb and 226,228Ra occurrences are found in the low permeability igneous and metasedimentary hydrogeological formations of Salamanca province. From a public health protection point of view, 4.4% of the total drinking water samples from intakes exceeded the Indicative Dose parametric value of 0.1 mSv, which is a not negligible number of samples, being very likely related to granitic and metamorphosed host rock under specific local conditions. This fact highlights the need for research and consideration of special surveillance of the groundwaters from these areas.

Assessment of Radium Equivalent Activity and Total Annual Effective Dose in Cassava cultivated around Ewekoro Cement Factory

In this study, cassava tubers cultivated in the Ewekoro cement area were investigated with the aid of Hyper Pure Germanium (HPGe) detector in order to assess the radionuclide content. Twenty-seven (27) samples of both arable soil and cassava tubers were studied at different sites to the epicenter of the mining activity. The results revealed the highest activity concentrations of K-40, Ra-226, and Th-232 to be 194.10, 63.92, and 76.90 Bq/kg, respectively, in soil to be at site 1, which was 50 m away from the cement mining site. Similarly, cassava reported the highest activity concentrations of 228.15 and 81.50 Bq/kg for K-40 and Ra-226, respectively, at sites 2, which was 150 m away from the mining site. However, the highest value of Th-232 in cassava was noted in site 1. Also, the highest values of Raeq for arable soil and cassava tubers were estimated to be 188.84 Bq/kg and 199.89 Bq/kg at site 1 and site 2, respectively. All the above results were higher than the recommended safe limits by a factor of 2. Moreover, the Total Annual Effective Dose of exposure by oral ingestion of cassava tubers for different age groups revealed children to have the highest level of exposure with the highest mean value of 7.98 mSv. This is followed by adults and infants, which reported 5.66 and 5.38 mSv, respectively, all at site 2. This result is far greater than the recommended safe limits of 1 mSv. Therefore, the results of the total averages of annual effective doses due to consumption of the three natural radionuclides in cassava tubers and other products from it by adults, children, and infants were found to be above the average annual ingestion radiation dose due to natural sources. Further statistical analysis of the results showed significant differences between sites 1 and 2 and between sites 1 and 3, where there was no statistically significant difference between sites 2 and 3.

Evaluation of Cs-137 and natural radionuclides on different marine biota (crustacean and fishes) along Beheira governorate Coast-Egypt: RESRAD biota

Purpose This work will focused on the environmental and radio-ecological impacts occurred on an Egyptian coastal region, based on the radiochemical measurement of 238U, 137Cs, 232Th, 40K. The novelty of the study was cleared by the using of new technique showing the integration of two biological RESRAD models, lead to a probabilistic estimation of the radionuclides bioaccumulation in different consumed marine organisms and determination the probability of human cancer risk at different ages. Material and methods The 20 water samples were collected and mounted into clean containers, and their decay products, were measured in Bq.L−1, using different quality assurance tools. The study will used different statistical analysis and different RESRAD modeling codes were used in the study to predict the degree of environmental and radio-ecological impacts at the studied area, this will be helpful in order to define the impacts resulted from the transferring and accumulation of different radionuclides. Results showed that the highest human dose conversion factor values of (5, 10, 15, with adult ages) were measured in Th-232 (mrem/pCi) while the lowest ingestion conversion factors values were observed in artificial 137Cs. On the other hand the highest values of external risk factor in case of (5, 10, 15 with adult age) were observed in artificial Cs-137(mrem/pCi), while the lowest value of external risk factor with the same ages were observed in U-238. This will lead to continual monitoring of artificial Cs-137 in different marine coastal regions. The arrangement of the bioaccumulation value (BIV) in Bq.kg−1 which being calculated by using RESRAD-Biota in case of crustacean animals will be as follow: U-238 > Th-232 > Cs-137, while the arrangement of BIV in case of fish animals will be: Cs-137 > U-232 > Th-232. On the other hand the arrangement of Internal Dose Conversion factors in case of crustacean animals will be: U-238 > Th-232 > Cs-137. While the arrangement of Internal Dose Conversion factors in case of fish animals will be: Cs-137> Th-232 > U-238. Conclusion RESRAD code’s results showed that the arrangement of the bioaccumulation and Dose Conversion factors were depend on the type of marine living organism. RESRAD code also showed that there are increments of the calculated external risk factor values which resulted from the adult than all the infants (5,10 and 15 ages) ages this may be related to the continuous replacement of new human’s body cells during the growth stages. The study results showed that, environmental bioaccumulation impacts of the artificial Cs-137 were very effective in both marine living organisms and human as this will support the relation between the ingestion Cs-137 in the body(inside the soft tissues), and the probability of the human cancer risk. On the other hand, study results showed the importance of using RESRAD BIOA code for the EIA's ecological and radiological studies which should be done for any future industrial coastal .projects.

Radiometric analysis of Brazilian commercial ornamental stones

The term “commercial ornamental stones” comprises different natural stones with different mineralogical components and the distribution and amount of natural radionuclides depended on the mineralogy. Few studies on natural radioactivity in ornamental stones carried out in Rio de Janeiro (Brazil) and the present work were carried out in order to analyze the distribution of activity concentration in these materials. The activity concentration of 238U, 235U, 226Ra, 232Th and 40K in Ornamental Stones measured using γ-ray spectrometry to estimate the radiation hazard as well as establishing a database for radioactivity levels. Samples were collected in stores in Rio de Janeiro, carefully transported, weighed, packed with PVC film and left to rest for at least 45 days to reach secular equilibrium. Samples analyzed by gamma spectrometry using a hyper pure germanium detector (HPGE). Detection efficiency for each sample was obtained using LabSOCS software. The activity concentrations for samples were within the ranges (0.83 ± 0.15 to 39.96 ± 1.19, 8.04 ± 2.54 to 111.36 ± 13.33, 0.43 ± 0.03 to 264.58 ± 0.98, BDL to 8.17± 0.65 and 1.30 ± 0.57 to 1567.01 ± 65.08) Bq⋅kg−1 for 238U, 226Ra, 232Th, 235U and 40K, respectively. The world average for building materials is 50 Bq⋅kg−1 for 238U, 50 Bq.kg−1 for 232Th and 500 Bq⋅kg−1 for 40K. In the present work, the average for granite was 19.43 ± 0.39 Bq⋅kg−1 for 238U, 56.70 ± 1.13 Bq⋅kg−1 for 232Th and 1113.28 ± 20.27 Bq⋅kg−1 for 40K, thus the values for 232Th and 238U are above the world average. Analyzing for the granite that showed the highest concentrations of activity the average values of Transport Rate was 3.12 ± 0.04 Bq⋅m−2⋅s−1, Emanation Rate was 0.16 ± 0.00 Bq⋅kg−1⋅s−1, Exhalation Flow was 530.26 ± 6.05 Bq⋅m−3, Effective Equivalent Dose Due to Radon Exposure was 0.78 ± 0.01 WLM⋅year−1 and Annual Effective Dose Due to Radon and Thoron was 7.02 ± 0.10 mSv⋅year−1. Annual Effective Dose Due to Radon and Thoron it is above the annual limit for public individuals which is 1 mSv⋅year−1 and below the occupationally exposed individual, which is 20 mSv⋅year−1 in an average of 5 years, it does not exceed the maximum level recommended by ICRP-60.

Особенности пространственного распределения 137Cs, 40K, 226Ra, 232Th в почвах города Кировска (Мурманская область)

The article presents the results of a study of soils in the city of Kirovsk. The purpose of the work is to establish the main regularities of the spatial distribution of natural and technogenic radionuclides in the urban soils of Kirovsk. To achieve this goal, soil samples were taken in all parts of the city. The following methods were used in the course of expeditionary work and laboratory research: soil, radiological, mathematical and statistical. The values of specific activity in samples of urban soils were: for technogenic 137Cs (from 3 to 48.3 Bq/kg), for natural radionuclides: 226Ra (from 11.8 to 44.2 Bq/kg), 232Th (from 9.8 to 34.8 Bq/kg), 40K (from 232.2 to 2086 Bq/kg). The values of the effective specific activity of natural radionuclides in urban soil samples ranged from 47 to 277 Bq/kg and 137Cs from 3.2 to 48.3 Bq/kg.

Natural radioactivity of residues from groundwater treatment facilities in Finland

The accumulation of naturally occurring radionuclides in solid residues was investigated from groundwater treatment facilities (GTFs) in Finland. Natural radionuclides U-238, Ra-226, Pb-210 and Ra-228 were found in various precipitates, sludges and filters at concentrations exceeding the general clearance level of 1 kBq kg−1 used for solid materials in the European directive 2013/59/Euratom. The accumulation of natural radionuclides in different solid residues was observed even when the activity concentrations in the untreated groundwater were relatively low, and when there was no measurable change in the concentrations between raw and treated groundwater within analytical uncertainties. Based on mass and activity balance considerations this is thought to be due to the large volumes of treated water per year. The exposure of workers to natural radiation from solid residues in the regular use of a groundwater facility was found not to be likely to exceed 0.3 mSv a−1 if the activity concentrations are <10 kBq kg−1 for U-238, Ra-226, Pb-210 and Ra-228. The worker exposure from solid residues is therefore likely to remain below the reference level of 1 mSv a−1, and indoor radon is more of a concern for the radiation protection of workers at GTFs. However, the natural radionuclide content in the different solid residues from groundwater treatment needs to be characterised properly to be able to ensure safety in the final use of the residues with respect to the potential exposure of the public.

RARE METALS RECOVERY FROM THE SORBENTS OF THE SORPTION CONVERSION OF EUDIALYTE CONCENTRATE

In order to develop the technology of eudialyte concentrate processing based on the use of sorption conversion, the patterns of metal extraction from sulphocationites saturated in the process and the regeneration of sulphocationite and solutions used for desorption for reuse are investigated. The compositions of saturated sorbents containing alkaline metals (sodium, potassium), alkaline earth and rare earth metals, titanium, zirconium (hafnium), niobium (tantalum), aluminium, iron, manganese, natural radionuclides are presented. Desorption with various solutions is investigated. It is found that niobium (tantalum) is most difficult to desorb. It is recommended to carry out two-stage desorption at a temperature of 20 °C: at first, with a 5 M NaCl solution, in which the majority of metals contained in the sorbent are converted into solution, and then desorption of zirconium and niobium with a 1 M Н2С2О4 solution. The issues of further processing of the obtained desorbates are considered. In accordance with previous studies, the impurity cake containing thorium, iron, aluminium, titanium is precipitated and separated from desorbates based on a 5 M NaCl solution through fractional neutralization, initially to pH 4, then the concentrate of rare earth elements is separated by neutralization to pH 7.5, and, finally, at pH ≥ 10, alkaline earth metals and manganese. Zirconium (hafnium) - niobium concentrate is precipitated from desorbates based on 1 M Н2С2О4 solution through neutralization with NaOH to pH 10, and then zirconium (hafnium) is leached from it using Na2CO3 solution. It is stressed that the sorbent in the H+-form is formed after desorption with a 1 M Н2С2О4 solution, which allows using it repeatedly to decompose eudialyte concentrate by sorption conversion. It is shown that the 1 M Н2С2О4 solution can be regenerated by electrodialysis from the Na2С2О4 solution obtained by precipitation of the collective zirconium (hafnium) - niobium concentrate.

ASSESSMENT OF NATURAL RADIONUCLIDES IN SOIL SAMPLES FROM MICHIKA, ADAMAWA, STATE NIGERIA

Naturally occurring radionuclides in the environment constitute about 85% of public exposure to terrestrial gamma radiation. These radionuclides can be found in sands,clays, soils and rocks, and many ores and minerals, commodities, recycled residues, and other appliances used by humans. There is therefore the need to assess the occurrence of natural radionuclides in Soil Samples from Michika, Adamawa State Nigeria. Forty-six (46) soil samples were collected across different location in Michika, Adamawa State, Nigeria. Gamma ray spectroscopy was used for the analysis. The results obtained show that the mean activity concentration for 226Ra, 232Th and 40K are 81.27, 101.28 and 324.79 Bq/kg respectively. These values are higher than the control value of 35,30 and 35 Bq/kg for 226Ra, 232Th and 40K set by UNSCEAR. The absorbed dose rate (D) ranges from 60.77 to 248.65 nGy/h, which is above the maximum UNSCEAR accepted value of 59nGy/h. The values of total annual effective dose lie between 0.08 and 0.31 mSv y-1 with mean value of 0.14mSv y-1. Also, the mean values of Radium Equivalent Activity were 251.11 Bq/kg. Almost all the value of Raeq were below the maximum recommended value. The mean value of total cancer risk range from 3.28E-6 to 1.3E-5 with mean value of 5.93E-6. All the mean values were above the acceptable range. It can be concluded that the soil is radiologically unsafe for human and animal use. Continuous radiological monitoring of the soil is recommended to safeguard the health of the populace.

Assessment of natural radioactivity and associated radiological risks from soils of Hakim Gara quarry sites in Ethiopia

One of the ways of minimizing radiation risks to workers and the public is assessing potential sites that are suspected of producing radiation. Among such locations, quarry sites stand out because areas of granite and other rocks, especially those of uranium family potentially have high concentrations of radiation. This study was aimed to assess one such quarry sites (Hakim Gara site), located near Harar town, Harari region-Ethiopia. To assess the radiological impact of natural radioactivity of quarry activities in the study area, activity concentrations of natural radionuclides 238U, 232Th, 226Ra and 40K in the soil samples were investigated by collecting twenty composite soil samples from different sites of the area. Measurements were carried out using high purity germanium (HPGe) Gamma Spectrometry detecting system for acquisition of data and making analysis using Genie 2000 software. From the result, mean Activity concentration of 238U, 232Th and 40K obtained were 51.9 ± 15 Bq/kg, 68.32 ± 9.75 Bq/kg and 220.0 ± 2.0 Bq/kg, respectively. Average Activity concentration of the 226Ra was 32.71 ± 2.02 Bq/kg. These values were used to calculate and estimate the radiological risks due to environmental radiation exposure contributed from the quarrying activities. The average external and internal hazard indices were 0.45 ± 0.09 mSv/y and 0.49 ± 0.23 mSv/y both of which were below the permissible limit of unity. The results obtained for 238U and 232Th were higher and significant from the world average which need further regulatory monitoring. The level of 40K was below the world average. Hence, this research provided a foundation for future studies on subsequent investigations and to aid realistic regulatory and policy decisions.