Concentrations Of 238U Research Articles

Accident tolerant fuel design optimization for SMART reactor

Fully Ceramic Microencapsulated (FCM) fuel is one of the most advancedfuel types for the next nuclear reactor generations. The use of uranium carbide fuel in FCM offers multiple benefits such as high fuel density, improved thermal conductivity and enhanced mechanical stability. Both UC and conventional fuel (UO2) have the same melting point. As a result, under reactor operating conditions, UC has better safety margins. In addition, FeCrAl is a promising cladding material. However, because of its greater thermal neutron absorption cross section, FeCrAl has a neutronic penalty when compared to Zircaloy leading to an annual reload requirement with high fuel enrichment. Owing to their low power density and excellent design, small modular reactors (SMRs) have exceptional inherent safety. In this work, we determined the optimum design of an accident tolerant fuel (ATF), with respect to neutronics, in SMART reactor using dense UC FCM (in contrast to the conventional UO2 fuel) and a combination of zircalloy and FeCrAl (FCM -Zircaloy, FCM -FeCrAl, FCM -combining of zircaloy and FeCrAl) as cladding to achieve better thermal conductivity as well as safer performance, while considering the required fuel enrichment for the proposed designs. The effective multiplication factor and burnup were calculated for neutronic assessment of the SMART core, the outcomes are showcased alongside a comprehensive assessment of the characteristics and prospective. The neutronic parameters were estimated using the stochastic MCNPX 2.6 code. We found that Fully Ceramic Microencapsulated -Uranium Carbide (FCM-UC) fuel type was more attractive than conventional UO2. The optimum cladding design as compared to the reference case and the other cases of (FCM-UC), was determined. When 50% FeCrAl cladding was employed, case 15 in our study emerged as the superior design, demonstrating maximum production of 239Pu due to higher initial concentrations of 235U and quantities of 238U. This work may offer recommendations for future optimized designs of the SMART reactor parameters.

Radioactivity characteristics of lignite and hard coals: Case study of Zonguldak (Kozlu), Konya (Karapınar) and Antalya (Pamucakyayla) in Türkiye

Abstract In this study, the radioactivity contents of Carboniferous Zonguldak-Kozlu hard coals, Carboniferous Antalya-Pamucakyayla hard coals and Pliocene Konya-Karapınar lignites were determined, then compared with the limit values determined by the authorized institutions and their hazard indexes were determined. The range of measured activity concentrations was from 16.2 Bq·kg−1 to 227.6 Bq·kg−1 for 238U, 20.6 Bq·kg−1 to 67.5 Bq·kg−1 for 232Th and 211.9 Bq·kg−1 to 515.5 Bq·kg−1 for 40K. The calculated mean absorbed gamma dose rate (D), radium equivalent activity (Raeq) and annual equivalent dose (AED) were 105.7 nGy·h−1, 227.9 Bq·kg−1 and 129.6 μSv·h−1, respectively. Although 238U and 232Th radionuclide activity concentrations are comparable to literature values, 40K activity concentrations were around three or four times higher than in UNSCEAR (2000) reports. As it poses a radiological risk, it is necessary to take the necessary precautions to reduce the negative effects on the environment and human health due to use of coals from Konya-Karapınar, Antalya-Pamucakyayla basins and to burn in a controlled manner.

Assessment of Natural Radioactivity and Associated Radiological Indicators in Water and Surface Soils Around Beta Glass Plc and Its Environs, Ughelli, Delta State, Nigeria

A radiometric assessment was conducted around Beta Glass plc using sodium iodide detector (3×3-inch NaI (TI)). The study collected 14 soil and 13 water samples from June to July 2022, analyzing radioactivity concentrations of 40K, 238U, and 232Th. The mean specific activity concentrations of 40K, 238U, and 232Th were 184.00±29.73 Bqkg-1, 14.55±2.50 Bqkg-1, and 8.60±1.04 Bqkg-1, respectively, in soil samples, but these elements' concentrations in water were 27.429±5.633 BqL-1, 6.661±1.421 BqL-1, and 2.518±0.361 BqL-1, respectively. The average activity concentrations of 40K, 238U, and 232Th were lower than the safe limit, and the corresponding radiation hazard indices for soil samples were all below the UNSCEAR-recommended acceptable limits. The mean activity concentrations of radionuclides in water samples were higher than the UNSCEAR's recommended international limits for 40K, 238U, and 232Th. Nonetheless, elevated radiological health hazards imply that cumulative dosages may cause cancer, even though these values might not pose an immediate health concern to the local community's people or the workforce.

Evaluation of natural radioactivity and radiological hazards in water sample of Tounsa Sharif, South Punjab, Pakistan

Radioactive material, especially Uranium, is very dangerous for human beings, creatures, and plants. It has been documented that the groundwater of the Dera Ghazi Khan Division in Punjab is contaminated with 238U. In this communication, the groundwater of the Tehsil Taunsa located at Indus River has been investigated. 144 samples of drinking water were collected from 48 villages/towns located in the area of about 500 km2 of the city. The samples were collected in the month of June, August and November, to concentrate on the temperature impact over the Uranium concentration. All samples were analyzed for 238U concentration using a fluorometric technique. The fluorometric technique was applied after pre-treatment of the sample. The analysis of the result revealed that groundwater obtained from this region contains a high value of 238U contents. Among the 48 trials, 26 samples were found below the permissible limit, while the remaining samples contained 238U contents above the permissible level. The sample collected from areas like, Qarim Wala, Jhoke Jamki, Basti peer, Tibi Qaisrani, Pehar Adda & Malana contained even up to the alarming level (30 μg l−1 to 54 μg l−1). In addition, it was observed that the sampling period had a significant effect on the contents, which were most prominent in June. This area being almost annually flooded by water from Rodh Kohi, who originated from Koh-e-Suleiman, may lead to such a high concentration of 238U. The additional reason could be the topographical and geological structure of the earth from which the samples were collected.

An approach for the indirect determination of 238U and 232Th content in ceramic products based on gross alpha and gross beta measurement

The aim of this work was the development of a procedure for the indirect characterization of 238U and 232Th in ceramic products using the quantification of gross alpha and gross beta activities in a low background proportional counter, which is less time consuming and cheaper than the direct radiochemical methods and gamma spectrometry. The procedure was applied, first, to a reference material used to fine-tune the procedure and statistical techniques, and then, for two types of ceramic products: micronized zircon and zircon flour samples, and spray-dried ceramic powders (atomized).This procedure requires obtaining linear regression models for estimating the activity of 238U and 232Th as a function of specific gross alpha and gross beta measurements. Regression models must be obtained for each type of ceramic material together with the range of application of the model, which depend primarily on the ratio between 238U and 232Th activities. The applications to micronized zircon and zircon flours, and spray-dried ceramic powders demonstrated that the models obtained for the indirect characterization of 238U and 232Th activities explain more than 95% of the variability in the data.In addition, those models were used for predicting the results of new validation samples. Regarding the micronized zircon and zircon flours, predictions were good for the 238U activity with a relative bias of less than 10%, while they were not so accurate for the 232Th activity, with a relative bias of less than 15% for most of the samples. For spray-dried ceramic powders, the predictions were quite good for the 238U activity with a relative bias of less than 20% irrespective of the cluster to which the validation sample belongs, and similarly for the 232Th activity.

37 years after the chernobyl: the current radiation status in Kocaeli, Turkey

This study aims to assess the artificial and natural radiation dose levels in certain districts of Kocaeli province within the Marmara region, 37 years after the Chernobyl nuclear accident, and evaluate the current status prior to potential nuclear leakage events from Zaporijya or other nuclear power plants. Radioactive concentrations of 232Th, 238U, 40K and 137Cs were determined using HPGe gamma spectrometry in 26 soil samples collected from the region of interest. The average concentrations were found to be 22.35 Bqkg−1 for 238U, 26.36 Bqkg−1 for 232Th, 368.34 Bqkg−1 for 40K, and 2.44 Bqkg−1 for 137Cs. Furthermore, the study revealed an absorbed dose rate of 41.73 nGyh−1, an annual effective dose equivalent of 51.18 µSvy−1, and an excess lifetime cancer risk of 0.00018.

Risk assessment due to natural radioactivity of stone dust and crushed stone Commercialized in construction stores in the state of Rio de Janeiro

A systematic study of the distribution of the Naturally Occurring Radioactivity in stone dust and crushed stone, has been carried out with an objective of establishing reliable baseline data on the radiation level and hence to evaluate hazard indices approach and the production of radioactive heat (RHP) due to radiation exposure to the workers and to the inhabitants of the studied area. Twenty-six samples have been collected from different locations in the State of Rio de Janeiro (Brazil). To calculate the specific activity, gamma ray spectrometry and a detector of High Purity Germanium (HPGe; Canberra, 30% relative efficiency) was used. The activity concentration of 238U, 226Ra 232Th and 40K ranged from 29.3 ± 18.6 to 206.8 ± 21.5 Bq kg−1, 30.3 ± 1.0 to 134.3 ± 1.8, 27.9 ± 0.7 to 86.2 ± 0.9 Bq kg−1, and 734.9 ± 35.1 to 1204.8 ± 53.5 Bq kg−1, respectively. The mean values of the Iex, Iin, Iγ, Iα, AUI, IRP112Rn, IPA, IPI and IYu indices were 0.68 ± 0.09, 0.92 ± 0.12, 0.93 ± 0.12, 0.43 ± 0.07, 0.88 ± 0.20, 1.25 ± 0.21, 0.34 ± 0.05, 0.75 ± 0.10, 0.63 ± 0.08 and 34. ± 6.31, respectively. The average radioactive heat production (RHP) of 2.01 ± 0.28 μ Wm−3 was above the values found in the literature, which may contribute to the heat flow in the study area because the raw materials that make up the samples showed a high value of environmental radioactivity. The Brazilian Hazard Index to assess the radiological risk of crushed stone and stone dust was created and the average value was 0.74 ± 0.10, a value below 1, which means only moderate control over the use of these materials, with no indication of restriction to the its use.

Gross alpha/beta and radionuclide activity concentrations in soil, plant and some fruits around the Tehran Research Reactor

Human activities usually have some contamination as effluents from chemical industries and radionuclides from nuclear reactors. For assessing the probable radioactive contamination in vicinity of Tehran Research Reactor, The gross alpha and beta radioactivity concentrations in soil, pine and cedar leaves and some selected fruits (fig, apple, berry and pomegranate) were investigated using an alpha/beta spectrometer during 2021–2022. Also, the concentrations of artificial and natural radionuclides in samples were investigated by the method of gamma spectroscopy. The gross alpha activity concentrations in soil, pine and cedar leaves and some selected fruits samples are from 0.05 to 0.35 Bq/gr and 0.07–0.31 Bq/gr and 0.04–0.18 Bq/gr, respectively. The gross beta activity concentrations in soil, pine and cedar leaves and some selected fruit samples are from 0.73 to 4.25 Bq/gr and 0.21–3.97 Bq/gr and 1.01–2.71 Bq/gr, respectively. Average activities concentration of natural radionuclide 232Th, 238U and 40K in soil, pine and cedar leaves and some selected fruits are 31.89–16.23–582.73 Bq/kg and 1.84–0.99–84.60 Bq/kg and 1.98–1.09–72.08 Bq/kg respectively. From artificial radionuclides, just 137Cs is recognized in soil sample and the range of 137Cs concentration in surface soils was observed to vary in the range 0.85–2.21 (Bq/kg). The result showed that the Tehran Research Reactor activities not have increased the environmental radioactivity and radiation level in the area.

Geophysical survey and radiometric assessment of aquifer strata and vulnerable groundwater quality of Ukwuani Ommunities in Delta State

The study assessed the aquifer strata and groundwater quality of Obeti, Umuaja, and Ebedei communities of Ukwuani, Delta State, Nigeria using electrical resistivity technique and sodium iodide [Na(TI)] detector. The electrical resistivity technique revealed that lithology has five to six geoelectric strata, which ranged from topsoil to clay formations with thickness of 0.6 to 6.0 m sits and aquifer resistivity range of 182.1– 6032.0 Ωm with depth of 29–70 m. These ranges indicate significant changes in the aquifer level and sufficient reservoirs for groundwater. To assess the activity concentrations of 238U, 232Th and 40K at the aquifer depth of 29–70 m groundwater, a total of fifteen groundwater samples were collect for analysis and the mean results are 9.00±1.24Bql−1, 4.82±2.95Bql−1 and 57.93±4.20Bql−1 respectively. These results are all above world threshold limits. However, the computed mean radiological health risk values for radium equivalent (Raeq), representative index (Iy), external hazard index (Hin), internal hazard index (Hex), absorbed dose rate (D), annual effective dose equivalent (AEDE), outdoor and indoor, and excess lifetime cancer risk (ELCR) outdoor and indoor are 20.35±5.78 Bql−1, 0.15mSvy−1, 0.056mSvy−1, 0.08mSvy−1, 9.55μGyh−1, 11.71mSvy−1, 46.84mSvy−1and 0.04×10−3, 0.16×10−3 and 0.20×10−3 for the addition of (ELCR) outdoor and indoor respectively. The computed mean radiological values are below world threshold limits. Hence, the studied communities’ drinking groundwater is safe radiologically. It is advised that government, oil and gas operators and individuals should drill above 30 m depth for quality groundwater and should be treated before usage. These values will serve as baseline data.

An Evaluation of the Radioactive Content of Ashes Obtained from the Use of Fuels from Recycled Materials by Co-Processing in the Cement Industry.

The co-processing of different wastes as fuels in the manufacture of cement clinker not only meets the objectives of a circular economy but also contributes to the reduction in CO2 emissions in the manufacture of Portland cement. However, waste used as alternative fuels, such as sludge or organic-rich residues, may contain naturally occurring radionuclides that can be concentrated during the combustion process. In this study, the presence of natural radionuclides (radioactive series of uranium, thorium, and 40K) and anthropogenic radionuclides (137Cs) in these wastes has been investigated by gamma spectrometry. Possible relationships between the radioactive content and the obtained chemical composition, determined by X-ray fluorescence, have also been studied by applying a principal component analysis (PCA). The results showed that the wastes with the highest radioactive content were sewage sludge with activity concentrations of 238U and 210Pb of 321 ± 38 Bq kg-1 and 110 ± 14 Bq kg-1, respectively. A correlation between radioactive content and Fe2O3 concentration was also observed. The annual effective dose rates to workers for the ashes estimated from the ash content ranged from 0.0033 mSv to 0.092 mSv and therefore do not pose a risk to workers as they are lower than the 1 mSv per year limit for the general public (DIRECTIVE 2013/59/EURATOM).

Spatial Distribution of Gamma Dose Rates and Radioactivity Levels in Some Parts of Iju Community in Ado-Odo Ota, Ogun State

This study investigates the background dose rates and radiological risk exposure to Iju community in Ado-Odo Ota. Using a hand-held calibrated gamma detector (RS-125 Gamma-Spec), the study area’s outdoor gamma dose rates and radionuclide activity concentrations of 40K, 238-U, and 32-Th were measured in situ. The results showed differing activities of the primordial radionuclides (40-K, 238-U, and 232-Th) with average values lying within the recommended limits, with the exception of 40K, which geologically can be caused by regional subsidence while on marine transgression. Based on statistical analysis, the correlation results verified that 40K, 238-U, and 232-Th were the primary causes of the elevated outdoor dose rates at Iju community. The International Commission on Radiological Protection (ICRP) specified allowable limits for radiation exposure, and the estimated mean hazard indices for the increased lifetime cancer risk in the research area exceeded these limitations. In order to ensure sufficient radiation protection, the research area needs attention right away.

Assessment of natural radioactivity levels and hazard indicators in Tarakeshwor Municipality, Nepal through in-situ technique and multivariate analysis

The evaluation of primordial radionuclide concentrations in rapidly urbanized and concrete-laden areas through the importation of construction materials from various regions of Nepal is both important and essential. This study utilized a portable gamma-ray spectrometer (PGIS 2) to analyze the distribution of three natural radionuclides: uranium (238U), thorium (232Th), and potassium (40K) in Tarakeshwor Municipality, Kathmandu, Nepal. The measured dose rates ranged from 70.22 nSv hr−1 to 163.66 nSv hr−1, with an average of 124.65±20.29 nSv hr−1, surpassing the global average of 59 nSv hr−1. The activity concentrations of 40K, 238U, and 232Th exceeded global averages, indicating relatively higher natural radioactivity concentrations in the region. Specifically, the average values for 40K, 238U, and 232Th were 935.26±172.30 Bq kg−1, 80.47±15.53 Bq kg−1, and 80.44±18.58 Bq kg−1, respectively. The calculated radium equivalent (Raeq) ranged from 132.26 to 351.22 Bq kg−1, and the annual gonadal equivalent dose (AGED) varied from 372.61 to 1028.81 μSv yr−1. The annual effective dose rates for indoor and outdoor environments were 0.54±0.09 mSv yr−1 and 0.15±0.03 mSv yr−1, respectively, both exceeding the global average. The representative level index (RLI) within the study area averaged 1.96±0.32, indicating an elevated radiation risk. The excess lifetime cancer risk (ELCR) values for outdoor and indoor environments were 0.52×10−3 ±0.09 ×10−3 and 1.87 ×10−3 ±0.31×10−3, respectively, surpassing the world average. Additionally, external hazard indices (Hex) ranged from 0.36 to 0.59, while internal hazard indices (Hin) ranged from 0.38 to 1.20, both indicating values higher than UNSCEAR recommendations. These findings underscore the necessity for further experimental analysis employing ex-situ equipment. The data generated in this study can provide a valuable baseline for future assessments and interventions in radiation risk management guidelines within the country.

Gamma ray spectrometric analysis and assessment of radiation hazards in soils of Mbeere North region, Kenya.

This study used gamma ray spectrometry to determine the radiological safety of construction soil sampled randomly from Mbeere North region, Kenya. The mean activity concentration of 232Th, 238U, and 40K was 149.7±2.8 Bqkg-1, 88.3±2.4 Bqkg-1, and 490±35 Bqkg-1, respectively. These averages exceed the world average for all the radionuclides. The radionuclides were non-uniformly distributed, with higher concentrations along the slopes and on the feet of the hills. The mean absorbed dose rate, indoor and outdoor annual effective dose, radium equivalent, external hazard index, and internal hazard index were 157.9±4.4 nGh-1, 0.58±0.02 mSvy-1, 0.39±0.01 mSvy-1, 340.7±9.2 Bqkg-1, 0.92±0.02 and 1.14±0.03, respectively. Among the radiation safety indicators, only the average internal hazard index exceeded slightly the acceptable safe limit. Therefore, soils of Mbeere North region are radiologically safe for use in brick making and construction of human habitats.

Investigation of natural radionuclides and radiation shielding potential of some commonly used building materials in Northwestern Nigeria

This study assessed the gamma-ray shielding potential of clay, sand, gypsum and kaolin commonly used as a building material in Northwestern, Nigeria. The radiological status of the samples was first evaluated by determining the activity concentrations of 238U, 232Th and 40K using NaI (Tl) detector after which elemental composition and mass density were determined using Neutron Activation Analytical Technique. After which the mass attenuation coefficients (MAC), linear attenuation coefficients (LAC), half value layer (HVL), tenth value layer (TVL), and effective atomic number (Zeff) were determined experimentally and theoretically using standard point sources of 137Cs and 60Co photon peaks (0.662 and 1.332, 1.173) MeV and Py-MLBUF software. The activity concentrations were found to range from 51 to 59 Bq kg−1 with a mean value of 59 Bq kg−1 for 238U, 24 to 27 Bq kg−1 with a mean value of 29 Bq kg−1 for 232Th, and 219 to 247 Bq kg−1 with a mean value of 247 Bq kg−1 for 40K which were about within the world recommended values of 33, 45 and 420 Bq kg−1 respectively. The results of the elemental compositions show that Si, Al, K, Fe, and Ba in clay and sand samples have concentrations in the range of 36.83–78.48%, 1.92–26.05%, 6.33–21.96%, 2.39–19.09%, and 0.09–1.44%, respectively, while in kaolin and gypsum, results revealed that Si, Al, K, Fe, and Ca range between 0.34 and 65.52%, 1.14–35.82%, 0.00–12.12%, 0.00–5.77%, and 0.00–96.6%, respectively. However, the concentrations of other elements such as Mg, Ti, Mn, Zn, Na, and Ba varied significantly with the samples. The results showed that clay has an average density of 1.96 g/cm3, sand has 2.32 g/cm3, kaolin has 2.63 g/cm3, and gypsum has the highest density with a value of 2.66 g/cm3 compared to other samples. During the measurements, a thallium-activated sodium-iodide NaI (TI) detector was used. A narrow beam transmission geometry condition was adopted for the measurements to ensure minimal scattered radiation. Absorption and attenuation of gamma beams as a function of sample thickness against gamma energy generally exhibit an increasing gamma ray behaviour as the sample thickness increases from 1 to 3 cm. The results showed that the gypsum, kaolin, sand, and clay were capable of attenuating 63.5%, 61.5%, 58.4%, and 44.2 of gamma-ray photons of energy 0.662 MeV at 3 cm thickness %, respectively, and 40.6%, 32.9%, 30.6%, and 27.3% of gamma energy 1.332 MeV at 3 cm thickness, respectively. The results showed that MAC, LAC, and Zeff of all the samples decreased with an increase in photon energy, while those of HVL and TVL increased. The experimental results for all the gamma-ray shielding parameters were found to be in good agreement with the theoretical values obtained using Py-MLBUF. The results have shown that all the samples have similar photon attenuation behaviours; however, gypsum has the best shielding potential than kaolin and this is attributed due to its highest density value.

The radioactivity levels and beta dose rate assessment from dental ceramic materials in Egypt

There is a lack of available data on the radioactivity levels of these materials, despite the potential risks they may pose to patients, dental technicians, and dentists. A total of forty samples were collected from different dental markets in Egypt. Using an NaI(Tl) detector, the gamma-ray spectrometer measured the activity levels of uranium-238, radium-226, thorium-232, and potassium-40. The findings revealed that the mean concentration of 238U (below the minimum detectable activity, MDA), 226Ra (135 ± 5 and 132 ± 5 Bq/kg), 232Th (187 ± 4 and 243 ± 8 Bq/kg), and 40K (1560 ± 52 and 2501 ± 89 Bq/kg) in feldspar and zirconia (ZrO2) dental ceramic samples, respectively, were all within the limits established by the International Organization for Standardization (ISO) and the European Commission (EC). The use of feldspar and zirconia dental ceramics to restore all teeth would result in an estimated maximum beta dose of 1.5 mGy/year to the oral tissue. The results suggest that there is no cause for concern regarding any additional beta dose to the oral cavity from the use of feldspar and zirconia dental ceramics.

Geochemical characteristics, hazards impact assessment and radiogenic heat production of the alkaline rocks.

This study primarily investigates the natural radioactivity level in alkaline rocks collected from the Wadi El-Dib ring complex (WDRC) in North Eastern Desert of Egypt, and assesses potential health risks associated with their use as decorative building materials. The work was accomplished using a high-purity germanium detector as well as ICP-MS and ICP-AES techniques. The WDRC composed essentially of trachyte, quartz syenite, granite and syenite. Geochemically, these rocks contain high SiO2 and alkalis with metaluminous to slightly peraluminous features. All rocks contain high concentrations of rare earth elements (∑REEs = 109-1075ppm), with clear enrichment in light REEs compared to heavy REEs [(La/Yb)N = 8.3-25.3. Radiometrically, the concentrations of the natural radioisotopes (238U, 232Th, and 40K) in the studied rock types surpassed the worldwide average values assigned for building materials by UNSCEAR. This elevation of the radioisotope concentration values is due to the presence of supplement minerals such as monazite, zircon, allanite, and rutile. Granites exhibit the highest mean concentrations of 238U (av. 164.24 ± 14.76Bq/kg) and 232Th (av. 214.37 ± 23.33Bq/kg), while trachytes demonstrate the highest 40K (av. 1352.56 ± 65.56Bq/kg) concentrations. In contrast, syenites exhibite the lowest mean concentrations for 238U (av. 54.51 ± 6.81Bq/kg) and 232Th (av. 56.76 ± 6.25Bq/kg), while quartz syenites display the lowest mean concentration of 40K (av. 1144.78 ± 96.19Bq/kg). The radiogenic heat production (RHP) associated with U, Th, and K range between 1.41 to 9.33μW/m3, exceeding the typical crustal mean value of 0.8 to 1.2μW/m3. The radiological parameters and indices evaluating risks of the outdoor and indoor radiation doses due to the investigated rocks were assessed. The results indicated that these rocks meet globally accepted values and safety standards (approved by UNSCEAR, ICRP, and EC) for surface building materials, as well as they underscore the importance of adhering to safety protocols to safeguard workers from radiation exposure within the WDRC area. Ultimately, the data herein provide a valuable database for assessing the compatibility of geochemical data and natural radioactivity level in WDRC rocks. Additionally, it reveals that from the radiological perspective, the investigated rocks are considered safe for use as decorative construction materials.

Study on the behavior of radionuclides in geologic samples from fault zone, Gabal Um Hamd, southwestern Sinai, Egypt

The present study concerned with the activity concentrations of natural radionuclides (238U, 234U, 230Th, 226Ra, 232Th, 40K and, 235U) in ten sedimentary rock samples collected from fault zone, Gabal Um Hamd, southwestern Sinai, Egypt. These samples were investigated to study their behavior during a part of geologic time. The activity concentrations were measured using γ-ray spectrometry (HPGe detector). The investigated samples were analyzed for major oxides using the XRF technique. The results demonstrated high average activity concentrations of 238U, 234U, 230Th, 226Ra, 232Th, 40K and, 235U than the worldwide average values as reported by UNSCEAR 2008. Theil diagram showed that there are accumulation and leaching of uranium in some samples in the two sides of the fault zone. It is noticed that the ages of uranium depositions for the samples collected from the downthrown of the fault zone vary from 121.5 to 440.1 ky, while for the sample collected from the upthrown of the fault is 210.9 ky. The 230Th/232Th activity ratios range between 4.55 and 91.04 for downthrown samples and between 4.75 and 6.05 for upthrown samples which are smaller than 20 except for two samples, indicating a contamination of the samples by detrital 230Th. After subtraction of the detrital 230Th, the corrected ages for downthrown samples vary from 119.1 to 231.7 ky while for upthrown samples vary from 164.4 to 390 ky.

Assessment of Extent of Radiological Exposures in Subsurface Dumpsite Sediments around the Residential Area of Oru-Ijebu South-West Nigeria

Assessment of naturally occurring radionuclides was carried out from 20 sampling points in a dumpsite systematically collected from varying subsurface depth intervals of 0-0.2m, 0.2-0.4m, 0.4-0.6m, 0.6-0.8m and 0.8m-1.0m, while the control samples were taken from two sampling points located 200m away from the dumpsite. The samples were consequently analyzed in the laboratory for natural radioactive emission where each activity concentration measurements of the radionuclides were determined; the natural radionuclides identified were 226Ra, 238U, 232Th, 40K utilizing gamma ray spectrometry with NaI (IT) detector. The mean activity concentrations recorded in Bqkg-1 for 226Ra, 238U, 232Th and 40K in the subsurface soil samples were respectively 2.53±0.60, 31.50±2.01, 27.20±1.63 and 340.39±19.48 in depth 0m−0.2m; 1.96±0.37, 28.2455±2.50, 23.84±3.07 and 320.59±24.07 respectively in depth 0.2m-0.4m; 1.24±0.41, 24.197±3.66, 19.86±2.46 and 290.71±28.99 respectively in depth 0.4m−0.6m; 0.80±0.34 Bqkg-1, 20.10±4.133, 16.10±1.54, and 259.04±34.22 in depth 0.6m−0.8m and 0.68±0.25, 18.509±2.08, 14.50±0.91 and 247±30.13 for 0.8-1.0m. The levels of radioactivity were then used to assess public dose rates and radioactive contamination thereby predicting changes in environmental radioactivity caused by poor waste management, industrial activities, and other human activities. In all the investigated sampling point 40K exhibited the highest activity concentration in 0-0.2m depth with the value of 383.45±19.4883 while Pr exhibited the lowest activity concentration with the value of 0.08±0.4252 in depth 0.8-1.0m. The mean activity concentration of 238U, 232Th and 40K, in the soil samples at the dumpsite were 20.80, 20.3 and 291.54 Bqkg-1respectively for 0-0.2m depth. These results were lower than the world permissible standard stated by UNSCEAR. It was generally observed that the activity concentrations reduced with 0-0.2m having the highest concentration values for both the dumpsite and the control sites, while the mean activity concentrations of 238U, 232Th and40K for the control sites were found to be 31.5045±2.0123, 13.145±1.4637 and 183.415±21.4465 respectively for 0-0.2m depth.

RECONNAISSANCE SURVEY OF MOTHBALLED URANIUM MINING FACILITIES AND SETTLEMENTS IN THE SOUTHERN PART OF THE NORTH-KAZAKHSTAN REGION

This paper provides data of the reconnaissance (preliminary) radiation survey of mothballed uranium mining facilities (MUMF) and adjacent settlements in the southern part of the North-Kazakhstan region (NKR). It is shown that, according to the level of EDR values, MUMF locations, when the public periodically stays in these areas, do not pose any radiation hazard. The exception is Grachevskoe MUMF where EDR values reached up to 14.0 µSv/h. Around the settlements, EDR values vary from 0.1 to 0.5 µSv/h. Elevated values are noted on highways. Regulatory values of radon EEVA were also found to be significantly exceeded in Toksan bi vil. A minor excess of radon EEVA was detected in Novoukrainka vil. Exceedance of the content of 238U up to 4 MPC was detected in sources of drinking water supply. Exceedances of up to 5 MPC for 238U were also found in natural waters. The total alpha activity showed an excess of up to 15 MPC. Natural waters exhibit an excess of up to 10 MPC. Based upon the data analysis during the reconnaissance survey, the Grachevskoe MUMF and Novoukrainka settlement were selected for a detailed survey.

Evaluation of Radioactivity Levels in Soil Samples from Assosa City in Benishangul Gumuz Region, Ethiopia

The specific activity concentrations of naturally occurring radionuclides in soil samples collected from suburban areas of Assosa City was measured using a High purity Germanium (HPGe) detector. The average specific activity concentrations of 238U and 232Th exceed the recommended safe value of 35.0 and 30.0 Bq kg−1, respectively. For 40K, the average activity concentration is below the recommended safe value of 400.0 Bq kg−1. The calculated mean value of the absorbed dose rate is 72.8 ± 3.72 nGy h−1 which exceed the recommended safe value of 59 nGy h−1. The calculated mean annual effective dose equivalent values for indoor and outdoor are 2.11 ± 0.1 mSv y−1 and 0.52 ± 0.02 mSv y−1, respectively. The calculated mean values of the internal hazard index, external hazard index, and gamma index are 0.43 ± 0.013, 0.56 ± 0.01, and 0.5 ± 0.01, respectively, and those values are below the recommended safe value of one. The mean value of excessive lifetime cancer risk is above the threshold value of 0.29 × 10−3. From this study, it is recommended that Assosa soil needs further investigations.