Concentrations Of 238U Research Articles

Assessment of the potential radiation hazards posed by Nubian sandstone, Egypt

The study found that the activity concentrations of the radionuclides 238U, 232Th and 40K in the sandstone are 32 ± 13, 29.6 ± 12.2, and 132.6 ± 86.4 Bq kg−1, respectively. These values are lower than the reported worldwide limits of 33, 45, and 412 Bq kg−1. According to the present study, the absorbed dose rate (Dair), the annual effective dose, and the excess life time cancer were all found to be below the worldwide mean. Pearson correlation, PCA, and HCA were used to analyze the data and identify patterns in the relationship between radionuclides and radiological hazards. A statistical analysis of the sandstones showed that the radioactive elements 238U, 232Th and 40K are the main contributors to the radioactive risk. The study suggests that the sandstone is safe to use. The levels of radioactivity are not high enough to pose a risk to human health.

Assessment of radiation dose level and excess lifetime cancer risk associated with dust samples collected from selected nursery and primary schools in Ife Central and Ife East, Osun State, Nigeria.

Abstract Primordial radionuclides are, among others, sources of radiation exposure to man. In this study, dust from some 24 nursery and primary schools in Ife Central and Ife East Local Government Areas (LGA) of Osun State were collected and analysed for 238U, 232Th, and 40K using CsI scintillation detector connected to a Universal Radiation Spectrum Analyser (URSA II) for spectrum analysis. From the specific activity concentrations of 238U, 232Th, and 40K, absorbed dose rates and radiological parameters were calculated. The mean activity concentrations of 238U, 232Th, and 40K in Bq/kg were found to be (45±2, 46±2), (56±5,60±5) and (669±76, 744±86) respectively for Ife Central and Ife East LGAs, however, the difference between the data sets from the two communities were not statistically significant. The total mean ± S.D (standard deviation) calculated over the whole study area were as follows; 238U= 45±11; 232Th=58±15 and 40K=702±196. The values of these radionuclides’ activities were higher than the world averages of 33, 45, and 420 for 238U, 232Th, and 40K respectively set by UNSCEAR. The mean absorbed dose rate in the air (in nGy/h) for Ife Central was 85±7 while for Ife East was 92±8. Both values were higher than the world average of 55 nGy/h. Also, the excess lifetime cancer risk was 1.66 × 10-3 for Ife Central and 1.8 × 10-3 for Ife East LGAs. Generally, Ife East LGA has higher activity concentrations than Ife Central LGA although the difference is not statistically significant.

Estimation of transfer factor from soil to cassava in Ethiope East, Delta State, Nigeria

Cassava is a very important staple food crop in Delta state. The aim of this research is to assess the activity concentration level and determine the transfer factor of radionuclide from soil to cassava in Ethiope Local Government Area of Delta state, Nigeria. The activity concentration of 40K, 238U and 232Th in soil and cassava samples collected from the study area were analysed using gamma spectrometry. A lead-shielded 3 x 3 inch coaxial type Sodium Iodide Thallium [NaI(TI)] doped detector crystal (Model No. 802 series, Canberra Inc.) coupled to a Canberra series multichannel Analyzer (MCA) (Model N0.1104) through a preamplifier was used. The results of the activity concentration in soil samples indicate that, 40K has the highest mean activity concentration ((38.66 ± 3.69) BqKg−1) with the highest value ((62.47 ± 5.67) BqKg−1) recorded at E2. The mean activity concentrations of 238U and 232Th are 3.65 ± 0.90 BqKg−1 and 0.46 ± 0.05 BqKg−1respectively. The peak values of 238U and 232Th are 5.07 ± 1.17 BqKg−1 and 0.98 ± 0.11 BqKg−1. From cassava, 40K varies from 75.06 to 200.08 BqKg−1 with the highest mean activity concentration of 99.62 ± 8.32 BqKg−1 and 200.08 ± 14.90 BqKg−1 as the highest value noted at C5. The mean activity concentrations of 238U and 232Th are 3.89 ± 0.93 BqKg−1 and 0.81 ± 0.09 BqKg−1 respectively. The maximum values of 238U and 232Th determined from the computation from cassava samples are 11.10 ± 2.48 BqKg−1 and 1.70 ± 0.18 BqKg−1. The results of this study show that the activity concentration of 40K, 238U and 232Th in the study area are lower than world average values of 420, 30 and 35 BqKg-1 in soil and cassava respectively, and it is therefore not harmful if consumed. The mean transfer factor of 40K, 238U and 232Th from soil to cassava are 3.12 ± 0.44, 0.95 ± 0.31 and 2.96 ± 0.91 respectively. The range of values of 40K, 238U and 232Th varied as 1.41 to 5.82, BDL to 2.98 and 0.21 to 9.35 correspondingly. Peak values of the TF were noted as 5.82 for 40K at E8, C8, 2.98 for 238U at at E9, C9 and 9.35 for 232Th at E9, C9. The high value of TR is accredited to the richness of the organic matter in the soil. The quick recycling of natural radionuclides through the soil-cassava suggests the presence of an internal cycling that help the build-up of the natural radionuclides.

Characterization of naturally occurring radioactive material dynamics in community water systems using groundwater from Ganghwa Island, Republic of Korea

Understanding the temporal behaviors of naturally occurring radioactive materials is important for the maintenance of community water supply systems for drinking groundwater on islands and in mountainous areas. Intensive field sampling in the Republic of Korea to characterize temporal variation in 238U concentration and 222Rn activity was performed for three community water systems on Ganghwa Island for ten years (2012–2022). 222Rn, a dissolved gas in groundwater, tended to decrease in activity as water moved from the source through community water systems, but no such trend was observed in 238U concentration. 238U and 222Rn behaviors in time series data for different CWSs reflected different geochemical processes and were differently classified accordingly. In particular, the 238U and 222Rn at points GJ and YH shows the signature of weathering: accompaniment by variation in pH and dissolved oxygen. In other time series, the 238U and 222Rn behavior shows the signature of cation exchange by seawater intrusion: accompaniment by dramatic variation in electrical conductivity. Random forest regression models developed to estimate the 238U concentration and 222Rn activity in groundwater boreholes exhibited reasonable threshold classification accuracy. The optimized threshold structure for 238U concentration and 222Rn activity variation with respect to the water quality variable of greatest statistical importance in each community water system random forest regression model corresponded to the geochemical process controlling the behavior of 238U and 222Rn in that groundwater borehole. Therefore, more intensive field sampling, covering the full data range that could emerge at each groundwater borehole, can aid in enhancing the accuracy of estimation of 238U concentration and 222Rn activity. Furthermore, the use of an in situ groundwater monitoring system in a random forest regression model facilitates the effective management of community water systems in the face of risk posed by naturally occurring radioactive materials.

Contributions of 238U, 232Th, and 40K to the radiogenic heat production in selected river sediment samples of South Africa

In this study, 16 sediment samples were collected from Bree, Klein-Brak, Bakens and uMngeni rivers of South Africa and were prepared, analysed and evaluated for the activity concentration of 238U, 232Th and 40K concerning its radiogenic heat production using a high-purity germanium detector. The results show that 238U is the prevalent radionuclide in radiogenic heat production, with 232Th and 40K emerging as trace elements. The mean activity concentrations are 28.97%, 63.69% and 7.34% for uranium, thorium and potassium, respectively, from all sampling locations. This shows that a high radioactive concentration of a specific radionuclide does not necessarily imply its increased contribution to radiogenic heat production. The radionuclide contributions to radiogenic heat production at all sampled locations are 59.39%, 35.11% and 5.50% for uranium, thorium and potassium, respectively. The mean radiogenic heat production rate in the study area ranged from 0.0180 μW m − 3 in sediment samples from the Bree River in Western Cape to 0.0072 μW m − 3 in sediment samples of uMgeni River in KwaZulu-Natal. All values obtained for this study are five times lower than the average continental radiogenic heat production of 1 μW m − 3 . This study provides insight into the radiogenic heat production rate due to the presence of radionuclides in all river samples.

Risk assessment and rare metals mineralization associated with alteration aspects of Rhyolite flow tuffs, Egypt

Argillic alteration and hematitization are the two extensive alterations that affected Um Safi rhyolite flow tuffs. Rare metal mineralization including radioactive minerals (thorite, uranothorite), Nb-bearing minerals (columbite, yettrocolumbite, Nb-rutile), zircon, REE-minerals (LREE-carbonate, xenotime) as well as molybdite, pyrite, fluorite, hematite and ilmenite have been identified by using Energy Dispersive Spectrometer (EDS) and are well recorded in argillic and hematitized samples. The investigated rhyolite flow tuffs show that the activity concentration of radionuclides changed from 1.2 to 453.2 Bq kg−1 for 238U, from 3.2 to 489.6 Bq kg−1 for 232Th, and from 31.3 to 88954.6 Bq kg−1 for 40K. The mean values of 238U, 232Th, and 40K activity concentrations are 90.8 ± 84.5, 122.9 ± 90.5 and 6286.7 ± 1562.2 Bq kg−1, respectively. The hazard factors are estimated. Their results exceeded the recommended limit. Thus, the investigated rhyolite flow tuffs are not safe to use in building materials and other construction industries. A multi-statistical approach is performed to show the correlation between the radioactive concentration and radiological hazard factors. This approach illustrates the positive correlation between uranium and thorium due to their contribution from the natural radioactive series—moreover, a strong correlation was obtained between potassium and all radiological parameters. Thus, the radioactive hazards impact in the present study is related to the presence of radioactive minerals such as thorite and uranothorite in addition to other accessory minerals.

Measurement of transfer factors from soil-to-plant/food crop of Naturally Occurring Radionuclide Materials (NORMs) in Nigeria: a review

One of the most crucial factors in the environmental safety assessment for the local and global communities, situated either in normal background areas or around nuclear facilities, is the uptake of radionuclides from soil by plants, which is typically stated as soil-to-plant Transfer Factor (TF) or Transfer Coefficient (TC). Such a metric, which can be defined as the ratio of radioactivity unit per dry crop mass to that of unit per dry soil mass, is necessary for environmental transfer models, which help to estimate the radionuclide concentrations in agricultural crops and calculate the dose exposure to people. In this article, a number of research studies conducted by scholars in Nigeria, published in both national and international journals, were compiled and reviewed for the purpose of providing an integrated and synthesized overview of the current state of knowledge on NORMs’ transfer factors in Nigeria. The activity concentrations of 40K, 226Ra, 228Ra, 232Th and 238U were measured by different research groups using gamma ray spectrometry coupled with either NaI(Tl) or HPGe detector. The activity concentrations of natural radioactivity in soils samples were generally higher than the values recorded in plant and food crop samples in almost all the research studies considered in the review. About 79% of the values of soil-to-plant transfer factor of 40K in all the studies under review were greater than the recommended value, while the values of transfer factors reported for 232Th and 238U were all greater than the recommended values.

Quantification of radiological hazards associated with natural radionuclides in soil, granite and charnockite rocks at selected fields in Ekiti State, Nigeria

Assessment of activity levels of radionuclides that exist in soil, granite, and charnockite rock samples is very crucial because it exhibits an enhanced elemental concentration of uranium (U) and thorium (Th) contributing higher natural background activity than usual in the environment and it may cause health risk to human health through the external and internal exposure. This study determined the radioactivity levels of 238U, 232Th, and 40K radionuclides in soil, granite, and charnockite rock samples collected from selected fields in Ekiti State, Nigeria using Caesium iodide CsI(Tl) scintillation gamma spectrometer. It also evaluated indices of the radiological parameters consisting of radium equivalent activity (Raeq), absorbed dose rate (DR), annual effective dose equivalent (AEDE), internal hazard index (Hin), and excess lifetime cancer risk (ELCR). The calculated average activity concentrations of 238U, 232Th, and 40K are 30.40 ± 0.71 Bq kg−1, 3.31 ± 0.05 Bq kg−1, and 222.25 ± 14.72 Bq kg−1, respectively, which were lower than their respective world average values. Comparatively, potassium concentrations in these collected samples have a higher value than concentrations of uranium and thorium (40K > 238U > 232Th). All the evaluated values of the radiological parameters (except DR) of the appraised radionuclides were below the global permissible limits. The granite rocks, charnockite rocks, and soils from Ekiti State in Nigeria do not pose any hazardous risk to humans, but continued monitoring is necessary when these materials are used as building materials, which cause long-term radiation exposure.

Analysis of the radiological dose and hazards assessment around swampy agricultural soil in Keffi, Nasarawa State, Nigeria

The present study analyzes radiological dose and hazard around the swampy agricultural soil in Keffi Local Government Area of Nasarawa State, using determined activity concentration (AC) of 238U, 232Th and 40K obtained from swampy agricultural soil samples, systematically collected from Ten (10) sampled points. Samples collected were further analyzed using a sodium iodide detector for activity concentrations of 238U, 232Th and 40K. The average AC of 238U, 232Th and 40K were 26.73±4.64, 9.77±2.57 and 1115.52 ±67.43 Bq/kg, respectively. The gamma absorbed dose rate (Dabs) ranges from 6.37E-01 to 2.33E+01 nGy/hr with a mean value of 6.10E+00 nGy/hr. The annual effective dose equivalent (AEDE) ranges from 8.12E-03 to 2.97E-01 mSv/yr with an estimated mean value of 7.77E-02 mSv/yr. The annual gonadal dose equivalent ranges from 4.48E-02 to 1.72E+01 mSv/yr with a mean value of 4.49E-01 mSv/yr. The calculated radium equivalent activity ranges from 1.44E+01 to 4.49E+02 Bq/kg with a mean value of 1.18E+02 Bq/kg, which falls below the recommended standard value of 3.7E+02 Bq/kg. The external and internal hazard index ranges from 3.89E-02 to 1.21E+00 mSv/yr with a mean value of 3.20E-01 mSv/yr, and 3.90E-02 to 1.41E+00 mSv/yr with a mean value of 3.70E-01 mSv/yr. The gamma hazard index ranges from 5.24E-02 to 1.84E+00 mSv/yr with a mean value of 4.83E-01 mSv/yr. The activity utilization index ranges from 8.65E-02 to 1.34E+00 mSv/yr with a mean value of 3.82E-01 mSv/yr, excess life cancer risk (ELCR) for both adult and child was found to be 1.94E-01 and 2.72E-01, respectively, higher than the recommended world average value of 0.29E-03. The high value of ELCR implies that residents around the study area have a high chance of developing cancer over a lifetime. Hence periodic radiological dose and hazard analysis is recommended to keep the exposure as low as reasonably achievable.

Evaluation of Specific Activity Concentration of 238U, 232Th and 40K in Soil and Rice Grains from Solid Mineral Mining Sites in Ikwo Area of Ebonyi State, Nigeria

Evaluation of specific activity concentration of 238U, 232Th and 40K in soil and rice grains from solid mineral mining sites in Ikwo area of Ebonyi state was carried out using a Digilert-200 Radiation Meter. The radiological impact of the radionuclides was calculated. The average value concentrations of radionuclides obtained were 170.53, 9.26 and 8.81 (in Bq.Kg-1) for 40K, 238U and 232Th respectively in soil samples and 113.77, 5.86 and 7.08 (in Bq.Kg-1) for 40K, 238U and 232Th respectively in rice grain. These values are below the world permissive value of 400, 35 and 30(in Bq.Kg-1) respectively. All the health risk parameters calculated in soil and rice were below world permissive values. For the radionuclides in rice samples, the average annual committed effective doses(in mSvy-1) for ages (<1 year), (1 – 7 years), (7 – 12 years), (12 – 17 years) and (>17 years) are 0.37, 0.05, 0.04, 0.03, 0.02 respectively. These results are less than the world permissive value of 1.00 mSvy-1. Generally, the study shows that the rice consumption was relatively safe radiologically with little contamination which could be attributed to human activities but there is tendency for long term health hazards in future such as the cancer due to doses accumulation. It is recommended that the various human activities that raise the activity concentration in soil in Ikwo mining area that should be reduced. The activity concentration of radionuclides level in the area should be periodically assessed.

Assessment of natural radioactivity and radon release potential of silurian black shales

Many countries are developing a radon action plan to provide decision-makers with a reliable tool for reducing the harmful effects of radon exposure in dwellings and among the general public and, accordingly, to implement land development strategies. Mapping the geogenic radon release in different geological environments could assist in delineating areas that require priority monitoring and regulation, as well as applying radon reduction techniques in newly constructed buildings. In this paper, the activity concentration of 238U, 226Ra, 232Th and 40K and the exhalation rate of 222Rn have been estimated for the Silurian black shales of Villasalto, a district in the south-eastern Sardinia (Italy). The radioactivity of 226Ra, 232Th and 40K radionuclides was found relatively high (256.32 ± 87.00 Bq.kg−1), low (44.16 ± 9.47 Bq.kg−1) and moderate to high (856.28 ± 392.41 Bq.kg−1) respectively. The radon emanation coefficient (E) and the radon production rate (PRn) have been calculated based on the analysis of the radon growth model inside a sealed chamber. E was found to correlate well with the activity concentration of 226Ra, as well as with the grain size of the soil/rock samples under investigation. PRn was relatively high, ranging from 212.54 to 524.27 Bq.m−3.h−1. Furthermore, the mean value of the main radiation hazard indexes (i.e., the radium equivalent activity, the outdoor gamma-ray dose rate and the annual effective dose) were found to be 299.07 ± 138.62 Bq.kg−1, 169.97 ± 75.58 nGy h−1 and 0.21 ± 0.09 mSv.y−1 respectively.

Measurement of Radionuclides and their Impact on the Environment Around Asphalt Plants in Delta State

Measurement of radionuclides and their impact on the environment around asphalt plants in some selected Asphalt mixing plant within Delta State, Nigeria was carried out. The Background Ionizing Radiation and the GPS of the location was measured using a well calibrated Gamma scout; Geiger counter multi-radiation meter and a GARMIN GPS meter and the result obtained at Raycon, DLA and Neodede Hot Asphalt Mixing Plants for outdoor exposure, shows a total mean value of (0.01492±0.038) (mRh-1), (0.01497±0.037) (mRh-1) and (0.01413±0.014) (mRh-1) respectively. The total mean values obtained in the selected radiological centers were all above the world average BIR level of 0.013 (mR?-1) as recommended by UNSCEAR (2000). These results were used to calculate some hazard indices such as the Equivalent dose (ED) in mSv??1, the absorbed dose rate (ADR) in nGy??1, Annual Effective Dose Equivalent (AEDE) and Excess Life Cancer Risk (ELCR). All the values obtained for each Parameter were above the world permissible limits as given by UNSCEAR (2000). The average activity concentration of 40K, 238U and 232Th in the soil of the three study areas were (603.21±30.94) Bq/Kg, (5.70 ±0.678) Bq/Kg and (6.91 ± 0.405) Bq/Kg. For 40K the average activity concentration was high and above the world recommended limit of 420 Bq/Kg (UNSCEAR 2000). 238U and 232Th were below the world recommended limits which are 33 Bq/Kg and 45 Bq/Kg. respectively. The Activity Concentration results were used to calculate the following radiological parameters: Absorbed gamma dose rate (DR) in (nGy/h), Annual Effective Dose Equivalent AEDE in (?Svy-1), the Radium Equivalent (Raeq), Excess Life Cancer Risk (ELCR) and External Hazard Index. All the calculated radiological Values were above the recommended limit given by (UNSCEAR 2000). Water samples in the study areas was also collected and the average activi

Gamma-ray spectrometric analysis of bore-well rock samples from agricultural area of Tamil Nadu

Natural gamma radiation exposure to humans can possess significant health risks when exposed either externally or internally. Though risks are not established at low doses, the exposure levels are set based on conservative approach. In this work, 22 bore-well rock samples were collected from the agricultural area of Dharmapuri district, Tamil Nadu to evaluate the radiation exposure to humans living in that area using a gamma-ray spectrometer. The results shows that, the activity concentration of 238U ranges from MDA to 87±2 Bq kg−1 with an average value of 25 Bq kg−1, and for 232Th it ranges from MDA to 10±2 Bq kg−1, and for the 40K it ranges from 167±9 to 669±10 Bq kg−1 with the mean value of 310 Bq kg−1. The various radiological parameters are calculated and compared with the world-recommended limit to assess the radiation hazards. To identify the relation among the natural radioisotopes, Pearson correlation analysis was performed between the radiological variables. It reveales that radionuclides 238U and 232Th strongly correlated with each other and radiological parameters. This implies that 238U and 232Th originated from the same source and 40K was derived from different sources.

Environmental Risk Assessment of Combined Radioactive and Chemical Pollution in Soil

The purpose of the study is to define the level of combined radiological and chemical contamination from the activities of soil and moss samples collected from the Eastern Black Sea region in Turkey and to assess the risk caused by the environmental radioactivity and chemical pollutants. The gamma, gross beta and gross alpha activities were measured in the soil and moss samples. The 238U, 232Th, 40K and 137Cs activity concentrations in the soil samples were measured in the range of 7.0 and 72 Bq kg-1 for 238U, 8.1 and 86 Bq kg-1 for 232Th, 203 and 1190 Bq kg-1 for 40K and 0.71 to 66 Bq kg-1 for 137Cs. In the moss samples, the 137Cs, 40K, 232Th, and 238U activity concentrations were found in the range of 1.03�0.27-24.23�1.39, 137�7-1340�68, 3.58�0.32-5.93�0.44 and 0.88�0.09-2.25�0.23 Bq kg-1, respectively. Contamination from toxic metals in the soils is categorized into enrichment factor, geo-accumulation risk, potential ecological risk and pollution load index. Co, Ni, As and Pb enrichments were determined in the extreme category in the 6 sampling sites. The pollution load index for the selected metals was found to be greater than 1. The geo-accumulation index in one sampling site showed contamination from heavy to severe levels of arsenic and lead.

Assessment of Soil to Cassava Transfer Factor of Radionuclides in Ughelli North Local Government Area, Delta State, Nigeria

Background:
 This research was conducted to estimate the activity concentration level of 40K, 238U and 232Th in soil and cassava and determine the transfer factor from soil to cassava in Ughelli North, Delta State, Nigeria.
 Materials and Methods:
 These were examined using gamma spectrometry and considering a lead-shielded 3 x 3inch coaxial type Sodium Iodide Thallium doped detector.
 Results:
 The mean activity concentrations of 40K, 238U and 232Th are 45.49 ± 4.28 BqKg−1, 3.15 ± 0.77 BqKg−1 and 0.56 ± 0.06 BqKg−1 respectively in soil samples and 134.08 ± 11.59 BqKg−1, 3.89 ± 0.93 BqKg−1 and 0.81 ± 0.09 BqKg−1 correspondingly in cassava samples. The mean transfer factor of 40K, 238U and 232Th from soil to cassava are 3.44 ± 0.75, 1.94 ± 0.32 and 1.34 ± 0.54 respectively. Peak values of the TF were noted as 8.52 for 40K at U18, D18, 25.58 for 238U at U12, D12 and 5.71 for 232Th at U11, D11.
 Conclusion:
 The activity concentration of 40K, 238U and 232Th in the area are lower than the world average values. Consequently, it will not pose any radiological hazard if consumed. The high value of Transfer factor is attributed to the richness of the organic matter in the soil and may indicate high ability to transfer radionuclides in the soil to food crops but from the concentration information, these radionuclides present in the soil are low as well as annual effective doses. There is no radiological risk of ingestion.

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.

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.

Radiological Safety Assessment of Agricultural Soil within the Bitumen Belt of Ondo State Nigeria, Using RESRAD-ONSITE and RESRAD-BIOTA Codes

Exploration and exploitation of bitumen can create radiation exposure pathways that must be considered in risk management scenarios. RESRAD-ONSITE and RESRAD-BIOTA developed by the US Department of Energy (US DOE) to assess contaminated sites, were used in the present study to predict the radiation dose and excess cancer risk associated with residual radioactive materials within Ondo State Bitumen Belt for the duration of 100 years, using site-specific parameters. The activity concentrations of 40K, 232Th and 238U in soil samples were determined by gamma-spectrometry and their average values were 35.85, 3.27 and 5.01 BqKg-1 respectively. While the estimated internal doses in biota due to 40K, 232Th and 238U were 7.54E-06, 3.03E-07 and 4.55E-08 Gy d−1 respectively for terrestrial animals, 6.69E-06, 3.68E-08 and 2.29E-08 Gy d−1 respectively for terrestrial plants, 6.49E-06, 5.88E-09 and 2.22E-08 08 Gy d−1 respectively for the Nigerian Dwarf Goat (NDG). The maximum total dose of 0.0229 mSvyr−1 was obtained at Agbabu at t = 30 years for an on-site resident farmer using the RESRAD-ONSITE Code, while the minimum total dose of 0.0014 was obtained at Araromi at t = 100 years. These values were by far lower than the National Research Council's acceptable limit of 0.25 mSvy-1. Likewise, the maximum Excess Cancer Risk (ECR) of 0.050 × 10−3 was obtained at Agbabu, while the lowest ECR value of 0.015 x 10-3 was shared by three communities: Omotosho (OMO), Akotogbo (AKG), and Ibekegbo (IKB). The observed low cancer risks in all the selected communities are of less human health concern since they are lower than the world safe value of 0.29 x 10-3. This implies that utilization of the studied soil for farming may not cause any immediate health hazard to the inhabitant but prolonged exposure might pose radiologically induced health challenges.

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.

Radon Gas Estimation from Building Materials

Radon gas originating from building materials is generally thought to cause low concentration. Investigation and estimation of radon levels originating from building materials are important in terms of public health due to the use of dense concrete in tunnel form type houses, which is a building type widely used in Turkey, even though a significant part of Turkey is an earthquake zone. In this article, the effects of different parameters such as 238U concentration in building materials, diffusion constant of building elements, emanation rate, and ventilation rate on radon gas concentration are investigated. As a result, it is concluded that in some cases (such as high diffusion coefficient and insufficient ventilation rate) in houses built with tunnel form concrete structures, the radon level arising from building materials can reach a level that cannot be neglected.