Health risk assessment for soil radioactivity around Shidaowan nuclear power plant in Shandong, China.

Monitoring radioactivity levels in the environment around nuclear power plants is of great significance to assessing environmental safety and impact. Shidaowan nuclear power plant is currently undergoing commissioning; however, the baseline soil radioactivity is unknown. The naturally occurring radionuclides 238U, 232Th, 226Ra and 40K, and artificial radionuclide (AR) 137Cs in soil samples around the Shidaowan nuclear power plant were measured to establish the baseline levels. Human health hazard indices such as external hazard indices (Hex), Radium equivalent (Raeq), outdoor absorbed dose rate (Dout), annual effective dose (AED) and excess lifetime cancer risk (ELCR) were estimated. The average concentration of 232Th, 40K, 137Cs, 238U and 226Ra were 42.6 ± 15, 581 ± 131, 0.68 ± 0.38, 40.13 ± 9.07 and 40.8 ± 12.8 Bq per kg, respectively. The average Hex, Raeq, Dout, AED and ELCR were 0.40, 146 Bq per kg, 68.8 nGy per h, 0.09 mSv per y and 3.29E-04, respectively. These data showed an acceptable level of risk to residents near the nuclear power plant and that the current radioactivity in the soil may not pose immediate harm to residents living close to the nuclear power plant. The observed lower AED and 40 K and 137Cs concentrations were comparable to other studies, whilst ELCR was higher than the world average of 2.9E-04. The commissioning of the Shidaowan nuclear power plant is potentially safe for the surrounding residents; further continuous monitoring is recommended.

Internal dose rate due to intake of uranium and thorium by fish from a dam reservoir associated with a uranium mine in Brazil.

Uranium mining can cause environmental impacts on non-human biota around mine sites. Because of this, the reduction in non-human biota exposure becomes an important issue. Environmental radioprotection results from the evolution of human radioprotection; it is based on dose rate to non-human biota and uses, as a biological target, and has harmful effects on populations. In the present study, a flooded impoundment created following dam construction in a uranium mine plant undergoing decommissioning was investigated. Internal dose rates due to activity concentration of natural uranium (Unat) and 232Th in omnivorous, phytophagous, and carnivorous fish species were estimated. Radionuclide activity concentrations were obtained by spectrophotometry with arsenazo III in the visible range. The dose rate contribution of 232Th was lower than that of Unat. There were no differences between the internal dose rates to studied fish species due to 232Th, but there were differences for Unat. A dose rate of 2.30·10-2 µGy∙d-1 was found due to the two studied radionuclides. Although this value falls below the benchmark for harmful effects, it is important to acknowledge that the assessment did not account for other critical radionuclides from uranium mining, which also contribute to the internal dose. Moreover, the study did not assess external doses. As a result, the possibility cannot be excluded that dose rates at the study area overcome the established benchmarks for harmful effects.

Analysis of internal gamma-ray dose to the public from brick as building material in Tamil Nadu, India.

Natural radioactivity due to 238U, 232Th and 40K in brick samples from Tamil Nadu was determined using gamma-ray spectrometry. The mean activity concentrations of 238U, 232Th and 40K, 69 ± 6, 62 ± 6 and 462 ± 23 Bq kg-1, are slightly greater than the world recommended limits of 35, 45 and 420 Bq kg-1, respectively, and they are compared with a similar work carried out across the world. The radiological parameters such as radium equivalent activity, Raeq (193 ± 17 Bq kg-1), internal hazard index, Hin (0.71 ± 0.06), and activity utilisation index, AUI (1.43 ± 0.13), was lower, whilst absorbed dose rate, DRin (89 ± 8 nGy h-1), annual effective dose equivalent, AEDEin (0.43 ± 0.04 mSv y-1), and excess lifetime cancer risk, ELCRin (1.52 ± 0.13 mSv y-1), are slightly greater than the world's recommended limit. Bi-variate statistical analysis was performed to corroborate the relationship between radionuclides and radiological hazards.

Measurement of 238 U, 232 Th, 222 Rn and 220 Rn Contents in Optical Contact Lenses: Resulting Alpha and Beta Equivalent Doses to the Eye Tissues of Adult Patients.

ABSTRACT: To estimate equivalent doses received by eye tissues of patients, contents of uranium ( 238 U), thorium ( 232 Th), radon ( 222 Rn), and thoron ( 220 Rn) were determined inside various optical contact lenses used for vision correction. 238 U, 232 Th, 222 Rn, and 220 Rn contents varied between (3.44 ± 0.24) mBq kg -1 and (18.3 ± 1.28) mBq kg -1 , (0.57 ± 0.04) mBq kg -1 and (3.53 ± 0.25) mBq kg -1 , (3.44 ± 0.24) mBq kg -1 and (18.3 ± 1.28) mBq kg -1 , and (0.57 ± 0.04) mBq kg -1 and (3.53 ± 0.25) mBq kg -1 , respectively. New external dosimetric models, depending on the cornea eye surface of patients, 238 U, 232 Th, and 222 Rn concentrations inside optical contact lenses, half-life of the emitting radionuclides, and exposure time of patients, have been developed. It has been shown that alpha-particles emitted by the 238 U and 232 Th series inside the studied optical lenses transfer their energies essentially to the cornea tissues whereas the emitted beta-particles may reach and lose their energies in the crystalline lens of eyes of patients. Alpha-equivalent doses received by eye tissues of patients due to the diffusion of 222 Rn and 220 Rn gases present in the considered optical lenses were determined. The higher value of the total (alpha plus beta) equivalent dose to the left and right eyes of adult patients wearing optical contact lenses (14 hours per day) has been found equal to 1.32 mSv y -1 cm - 2 . It is recommended for patients to reduce the wearing period of optical contact lenses to reduce eye disease risks such as cataract.

Assessment of radioactivity concentration for building materials used in Babadogo Estate, Nairobi City County, Kenya.

Natural radioactive materials in certain conditions can get to hazardous radiological level. The aim of the present work was to evaluate the natural activity concentration from sampled building materials collected from different locations in Babadogo Estate within Nairobi City County. The analysis done using gamma ray spectrometer, which was put into action for spectral data acquisition and then analysis. The activity concentration levels of 238U, 232Th and 40K for the selected samples of building materials was measured by the use of gamma ray spectrometry method. The analyzed data compared with the standard acceptable values. The activity concentration in 40K varied from 55 ± 3 to 2647 ± 132 Bq kg-1, giving an average (sum of all values divided by 33) value of 831 ± 42 Bq kg-1; 238U varied from 39 ± 2 to 3602 ± 180 Bq kg-1, giving average figures of 378 ± 19 Bq kg-1 and 232Th ranged from 5.000 ± 0.300 to 4213 ± 211 Bq kg-1, giving average figure of 290 ± 15 Bq kg-1. The calculated average figures for activity concentration surpassed the world average values of 420, 33 and 45 Bq kg-1 in 40K, 238U and 232Th, respectively.

Bifunctional solid-state ionic liquid supported amidoxime chitosan adsorbents for Th(IV) and U(VI): Enhanced adsorption capacity from the synergistic effect.

Uranium and thorium of symbiotic relationship commonly appear in one kind of raw or spent ore. The simultaneous enrichment toward both metals in the first step is essential during many hydrometallurgy processing. Therefore bifunctional solid-state ionic liquid supported amidoxime chitosan (ACS) adsorbents were developed to simultaneously adsorb the two metal from the aqueous solution. The adsorption capacity of the bifunctional adsorbents toward uranium and thorium were significantly superior to the ionic liquid-free amidoxime chitosan, obviously proving the synergistic effect. For both uranium and thorium, the adsorption capacity in the consequence of ACS-[N4444][DEHP], ACS-[N4444][EHEHP], ACS-[N1888][DEHP] and ACS-[N1888][EHEHP] prove the steric effect and PO bonding played important roles in the adsorption. Study on isotherms and kinetics demonstrated the adsorption of ionic liquid-ACS adopted monolayer and chemical way. The ΔGo of very small negative values highlighted ionic liquid-ACS were prone to adsorb uranium and thorium. The study showed feasibility of bifunctional solid-state ionic liquid supported amidoxime chitosan adsorbents for Th(IV) and U(VI).

Estimation of natural radioactivity in the soil samples around the uranium site, royal village, Khandela, Sikar district, Rajasthan.

The measurements of activity concentration of radium ( 226Ra ), thorium ( 232Th) and potassium ( 40K ) natural radionuclides using high purity germanium ( HPGe ) detector to assess harmful effects on people residing around Royal Uranium Site, Sikar, Rajasthan, India. The activity concentrations range from 29.03 ± 3.72 to 69.95 ± 4.07 Bq/kg for 226Ra with a mean value of 47.01 Bq/kg, 57.99 ± 6.13 to 113.94 ± 6.54 Bq/kg with a mean value of 86.56 Bq/kg for 232Th,678.19 ± 76.36 to 1426.55 ± 81.32 Bq/kg for 40K with a mean value of 1195 Bq/kg. Average Radium Equivalent Activity was measured 261.59 ± 35.48 Bq/kg. The total outdoor absorbed gamma dose rate ranged from 78.42 to 157.91 nGy/h with a mean value of 122.12 nGy/h.The average annual effective dose equivalent outdoors and indoors was found 0.75 mSv.Mean external (Hex) and internal (Hin) hazard indices are measured 0.70 and 0.82, respectively, for the study area.

Estimation of radioactivity in soil and drinking water samples from Northern Gulbarga District of Karnataka.

The gamma activity of the radionuclides238U, 232Th and 40K were measured in surface soil samples collected from 40 villages of Aland, Afzalpur, Ganaghapur and Kamalapur talukas of Northern Gulbarga district, Karnataka. The gamma activity of natural radionuclides were measured using 4" × 4" NaI (Tl) scintillation detector, the spectrum was analysed using a PC based 1 k MCA (winTMCA 32 scinti SPEC) and the 222Rn activity concentrations in drinking water were determined by the Emanometry method. The activity of 238U, 232Th and 40K was found to be in the range from 14.3 ± 0.3 to 64.5 ± 6.1, 15.4 ± 0.2 to 95.0 ± 4.1 and 21 ± 06 to 323 ± 09 Bq kg-1, respectively. Outdoor AED from 0.023 to 0.07 mSv y-1 and all the radiological hazards indices were well within the safe limit. The 222Rn activity in ground water is found to vary from 1.11 to 66.6 Bq l-1. The total annual effective doses due to 222Rn inhalation and ingestion range from 3.02 to 181.81 µSv y-1, respectively, with an average value of 77.18 µSv y-1.

Combined Thermodynamic, Theoretical, and Biological Study for Investigating N-(2-Acetamido)iminodiacetic Acid as a Potential Thorium Decorporation Agent.

The most effective approach to mitigate the toxic effects of internal exposure of radiometals to humans is metal-ligand (ML) chelation therapy. Thorium (Th)-induced carcinogenesis as well as other health hazards to humans as a result of chronic internal exposure necessitates the development of efficient Th-decorporating agents. In this regard, chemical and biological studies were carried out to evaluate N-(2-Acetamido)iminodiacetic acid (ADA), a comparatively cost-effective, readily available, and biologically safe complexing agent for Th decorporation. In the present work, detailed thermodynamic studies for complexation of ADA with Th(IV) have been carried out to understand Th-ADA interaction, using potentiometry, calorimetry, electrospray ionization mass spectrometry, and theoretical studies, followed by its biological assessment for Th decorporation. Thermodynamic studies revealed the formation of strong Th-ADA complexes, which are enthalpically as well as entropically favored. Interestingly, density functional theory calculations, to obtain a thermodynamically favored mode of coordination, showed the uncommon trend of lower denticity of ADA in ML than in ML2, which has been explained on the basis of stabilization of ML by hydrogen bonding. The same was also reflected in the unusual trend of enthalpy for Th-ADA complexes. Biological experiments using human erythrocytes, whole human blood, and lung cells showed good cytocompatibility and ability of ADA to significantly prevent Th-induced hemolysis. Th removal of ADA from erythrocytes, human blood, and normal lung cells was found to be comparable with that of diethylenetriamine pentaacetate (DTPA), an FDA approved decorporating agent. The present study contributed significant data about Th complexation chemistry of ADA and its Th decorporation efficacy from human erythrocytes, blood, and lung cells.

Assessment of radioactivity levels and radiological hazard indices in phosphate and phosphate mine waste samples from Algeria.

Phosphate ore is the starting raw material for production of all phosphate products including fertilisers phosphate waste. It can be of sedimentary, volcanic or biological origin. Like any other geological material found in nature, it contains various amounts of naturally occurring primordial radionuclides, such as 238U series, 232Th series and 40K. Gamma-ray spectrometry was used to assess natural radioactivity levels and radiological hazard indices in phosphate samples. In this paper, the specific activity concentrations of 226Ra, 232Th and 40K of phosphate ores, merchant and mine waste samples were determined. Based on the activity concentrations, the radiation hazard indices (Raeq, Hex, Hin and I𝛾𝑟), and the radiation doses (D, AED and ELCR) were calculated. The results were discussed and compared with those from other studies as well as recommended safety limit values.

Parallels between natural Oklo reaction zones and industrial reactors dynamics.

The first man-made nuclear reactor was developed by Fermi and collaborators at the University of Chicago and reached criticality in December 1942. This was the confirmation that men were able to use sustained fission reactions in order to produce energy. Following this success, nuclear reactors studies gave rise to several families of reactors corresponding to different orientations and technical choices. They are linked mainly to the choice of fuel (natural uranium, enriched uranium, plutonium, thorium), coolant (water, carbon dioxide, helium, sodium, ...) and moderator for slow neutron reactors (graphite, light water, heavy water). Out of all these choices, the pressurized water reactor (PWR) family is the closest to the Oklo natural reactors. Many intriguing similarities are observed and discussed in the present article. Our present-day understanding of the PWR operating conditions has been a great help for understanding the Oklo reactors.

Natural radioactivity in mineral phosphate fertilizers and its impacts on human health: an overview.

Humans are constantly exposed to radioactivity present in rocks, soils, and water, mainly from materials in the Earth's crust that contain chemical elements belonging to the radioactive series of uranium and thorium. An important anthropogenic source of these natural radioisotopes to the environment is fertilizers, widely used to increase agricultural productivity. Exposure to ionizing radiation can become a public health problem worldwide, since it is related to the development of different cancers in humans. The present study aimed to survey research on the radioactive content in different types of mineral phosphate fertilizers used around the world through a comprehensive review of the Scopus and Web of Science databases. About 80 scientific articles fit the purpose of this review. The concentration activity values found varied widely from one country to another, and there is no specific legislation that determines the maximum allowed limits of radioisotopes in these agricultural inputs. In addition, there are still uncertainties regarding the impact of natural radioactivity from fertilizers on human health, highlighting the need for further investigations on the subject.

Geochemical behaviors of uranium and thorium during weathering and pedogenesis of carbonate rock: constraint from their speciation.

During weathering and pedogenesis of carbonate rock with poor-uranium (U) and thorium (Th), U and Th present the characteristics of strong leaching (especially U) and significant residual enrichment, the cause of which is still unclear. In this paper, a weathering profile developed by dolomite in karst area of Guizhou province in southwest China was selected, which showed zonation characteristics of bedrock (Y), powdery rock (Yf), and soil layer (T1 to T12) from the bottom to up. Through the determination of the occurrence speciation of U and Th in Y and weathering profile, combined with mineralogical, geochemical characteristics, and element mass balance calculation, the constraints of U and Th speciation on the geochemical behavior of U and Th during the weathering of carbonate rock were revealed. The results proved that U and Th in Y preferentially existed in acid insoluble phase, for example, the contents of U and Th in Y were 0.90 mg·kg-1 and 0.28 mg·kg-1, respectively, while those in acid insoluble matter were 2.34 mg·kg-1 and 2.57 mg·kg-1, respectively, but because the mass percentage of acid insoluble matter was extremely low (0.95%), the mass percentages of U and Th in the acid soluble phase in the whole rock were absolutely superior (96% of U and 86% Th). The U and Th in the acid soluble phase of Y were mainly adsorbed on the crystal surface of carbonate minerals or existed in the cement, and the U and Th in the carbonate lattice only accounted for a small proportion. From Y to Yf with the initial dissolution, U and Th released from the surface of carbonate minerals and cements were in carbonate-rich alkaline environment, and these portions of U and Th were leached out, resulting in strong loss of U and Th in the Yf (the loss rates are 83% of U and 65% of Th, respectively). From the Yf to the overlying soil layer T1, the carbonate components were completely dissolved, and the U and Th released from the carbonate lattice showed different behaviors, where U was completely leached and Th tended to stay in the weathered residue. Thus, in the soil layer T1 formed by Y or Yf , the residual U was the inheritance of the U in the acid insoluble phase of Y; For Th, it not only inherited the Th of acid insoluble phase of Y, but also superimposed the Th from carbonate lattice in Y. On the other hand, during the evolution process from Y to Yf and to soil layer T1, with the dissolution of carbonate, the acid insoluble phase also showed a significant tendency of chemical weathering. However, the U and Th in the Y acid insoluble phase were not leached with the decomposition of the acid insoluble phase but were redistributed among the residual phases. For the geochemical behaviors of U and Th in the evolution of soil profile (T1~T12), they were subjected to the occurrence speciation of U and Th in T1 and the change of U and Th occurrence speciation with the upward direction of soil profile. The U and Th released from the carrier minerals were mainly redistributed among the residual solid phases, which weakened the intensity of their further loss. This study deepens the understanding of the geochemical behavior of radionuclides in karst environment and provides reference for the treatment of radioactive pollution in karst areas.

Evaluation of radioactivity levels and radiological hazards of some endemic plants used as medicine in Ankara, Turkey.

In this study, natural radioactivity levels (226Ra, 232Th, and 4 K) of some medicinal plant samples with known anti-oxidative properties, which are frequently consumed by animals and humans, were obtained from Ankara province and its surroundings (Mamak, Kizilcahamam, Beypazari, Kahramankazan, and Polatli districts) were determined using a thallium-doped sodium iodide NaI(Tl) gamma spectrometry. By using the determined natural radioactivity concentrations in the collected plant samples, the number of radiological doses that people could be exposed by consuming these plants was calculated. As a result of the study, 226Ra, 232Th, and 4 K radioactivity concentration ranges of the plant samples were found be 14.69 ± 1.27-59.08 ± 3.12 Bq kg-1, 1.78 ± 0.04-50.05 ± 2.76 Bq kg-1 and 207.24 ± 34.09-826.13 ± 25.40 Bq kg-1, respectively. The highest 226Ra, 232Th, and 4 K activity concentrations were measured in Astragalus densifolius subsp. ayashensis (Kahramankazan), Astragalus kochakii (Kahramankazan) and Rumex patientia (Patience Dock) (Kahramankazan) plants, respectively. The lowest 226Ra, 232Th and,4 K activity concentration plants were determined respectively as Rumex patientia (Mamak), Lavandula angustifolia (Kizilcahamam), and Astragalus acikirensis (Polatli). The establishment and routine repetition of environmental radioactivity monitoring programs in each region are important for human and animal health, and the results of this study gain importance for Ankara and its surroundings in terms of environmental health.

Analysis of radioactivity in commercially available products aiming to improve health and wellness.

There are products available on the online market that are claim to contain unique 'energies' that can improve health and wellness by eliminating toxins and pains and energising food and drinking water. We investigated these products by alpha and gamma spectrometry, and the analysis showed that they contained a few to hundreds of kilobecquerels per kilogram of naturally occurring radionuclides from the 232Th and 238U series. The committed effective dose for an adult drinking water that had been in contact with these products just once was estimated to 12 nSv. Considering a worst-case scenario for the workers inhaling the radioactive substance, 1 d of work would result in an effective dose of 0.39 mSv. The product descriptions do not mention the radionuclide content, and concerns are raised for the consumers and workers exposed to these products with no knowledge of the radioactive content.

Geochemical distributions of natural radionuclides in surface soils and sediments impacted by lead-zinc mining activity.

This study investigated the distribution features of uranium-238 (238U), radium-226 (226Ra), thorium-232 (232Th), and potassium-40 (40K) and evaluated the associated environmental radiological hazards of the topsoil and river sediments in the Jinding lead-zinc (Pb-Zn) mine catchment from Southwest China. The activity concentrations of 238U, 226Ra, 232Th, and 40K ranged from 24.0 ± 2.29-60.3 ± 5.26 Bq.kg-1, from 32.5 ± 3.95-69.8 ± 3.39 Bq.kg-1, from 15.3 ± 2.24-58.3 ± 4.92 Bq.kg-1, and from 203 ± 10.2-1140 ± 27.4 Bq.kg-1, respectively. The highest activity concentrations for all these radionuclides were primarily found in the mining areas and decreased with increasing distance from the mining sites. The radiological hazard indices, including radium equivalent activity, absorbed gamma dose rate in the air, outdoor annual effective dose equivalent, annual gonadal dose equivalent, and excess lifetime cancer, revealed that the highest values were observed in the mining area and downstream, specifically in the vicinity of the ore body. These elevated values exceeded the global mean value but remained below the threshold value, suggesting that routine protection measures for Pb-Zn miners during production activities are sufficient. The correlation analysis and cluster analysis revealed strong associations between radionuclides such as 238U, 226Ra, and 232Th, indicating a common source of these radionuclides. The activity ratios of 226Ra/238U, 226Ra/232Th, and 238U/40K varied with distance, suggesting the influence of geological processes and lithological composition on their transport and accumulation. In the mining catchment areas, the variations in these activity ratios increased indicated the impact of limestone material dilution on the levels of 232Th, 40K, and 238U in the upstream region. Moreover, the presence of sulfide minerals in the mining soils contributed to the enrichment of 226Ra and the removal of 238U caused those activity ratios decreased in the mining areas. Therefore, in the Jinding PbZn deposit, the patterns of mining activities and surface runoff processes in the catchment area favored the accumulation of 232Th and 226Ra over 40K and 238U. This study provides the first case study on the geochemical distributions of natural radionuclides in a typical Mississippi Valley-type PbZn mining area and offers fundamental information on radionuclide migration and baseline radiometric data for PbZn deposits worldwide.

Cold season dose rate contributions from gamma, radon, thoron or progeny in legacy mines with high natural background radiation.

In areas with high natural background radiation, underground cavities tend to have high levels of airborne radionuclides. Within mines, occupancy may involve significant exposure to airborne radionuclides like radon (222Rn), thoron (220Rn) and progeny. The Fen carbonatite complex in Norway has legacy mines going through bedrock with significantly elevated levels of uranium (238U) and especially thorium (232Th), and significant levels of their progeny 222Rn and 220Rn. There are also significantly elevated levels of gamma radiation in these mines. These mines are naturally chimney ventilated and release large volumes of air to the outdoors giving a large local outdoor impact. We placed alpha track detectors at several localities within these mines to measure airborne radionuclides and measured gamma radiation of bedrock at each locality. The bedrock within the mines shows levels up to 1900 Bq kg-1 for 238U, 12 000 Bq kg-1 for 232Th and gamma dose rates up to 11 µSv h-1. Maximum levels of airborne radionuclides were 45 000 Bq m-3 for 220Rn and 6900 Bq m-3 for 222Rn. In addition, we measured levels of thoron progeny (TnP). In order to estimate radiation dose contribution, TnP should be assessed rather than 220Rn, but deposition-based detectors may be biased by the airflow of mine-draft. We present dose rate contributions using UNSCEAR dose conversion factors, and correcting for airflow bias, finding a combined cold season dose rate within these mines of 17-24 µSv h-1. Interestingly, fractional dose rate contributions vary from 0.02 to 0.6 for gamma, 0.33 to 0.95 for radon and 0.1 to 0.25 for TnP.

Radiological assessment of irrigation water used in Rustenburg, South Africa.

Water is an essential input in agricultural production, which is why it plays an important role in food security. According to the World Bank, water irrigated agriculture represents about 20% of the total cultivated land and 40% of the total food produced globally. This makes water a direct and indirect route of radiation exposure to humans via contact, ingestion and consumption of agricultural products. Radiological assessment of irrigation water around Rustenburg, one of the mining and industrial cities in South Africa, is investigated in this study. The activity concentrations of 238U, 232Th and 40K in irrigation water samples were determined using the total mass elemental concentrations of uranium, thorium and potassium, measured using inductively coupled plasma mass spectroscopy. The activity concentrations of 238U and 40K range from 1.24 × 10-04 to 1.09 × 10-02 Bq/l, and 7.07 × 1000 to 1.32 × 10+01 Bq/l, with mean activity concentrations of 2.78 × 10-03 and 1.16 × 10+01 Bq/l, respectively. The activity concentration of 232Th was found below the detection level in all sampled irrigation water. Estimated annual effective dose because of ingestion because of 238U and 40K was also found to be below 120 µSv/y for 238U and 232Th, 170 µSv/y for 40K and a total of 290 µSv/y by the United Nations Scientific Committee on the Effects of Atomic Radiation. The estimated radiation dose and lifetime cancer risk indices indicate insignificant radiological risk, making the irrigation water safe for domestic and agriculture purposes.

Radiogeochemistry, mineralogy, lithology, radiogenic heat production, and health implication using airborne radiometric data of Ilesha and its surroundings.

The current study analyzed and interpreted airborne radiometric data from Ilesha's basement complex rock and its surroundings. At the surface, the concentrations of the most frequent primordial radionuclides notably K, elemental concentration of uranium eU, and elemental concentration of thorium eTh were measured. The weighted mean elemental and activity concentrations were 0.85%, 2.75 ppm, 10.22 ppm, and 267.54 Bq kg-1, 34.41 Bq kg-1, 41.51 Bq kg-1 for 40 K, 238U, and 232Th, respectively. The low concentration of 40 K was certainly due to the effects of weathering, kaolinization of granites, and pedogenesis activities. The abundance of uranium was ascribed to the availability of uranium minerals such as allanite, apatite, and sphene with accessories minerals, while that of thorium was due to minerals such as cheralite, thorite, uranothorite, thorianite, and uranothorianite with accessories minerals. The RPHR weighted mean 1.48 µWm-3 compared to the earth's crust mean between 0.8 and1.2 µWm-3 was higher due to significant presence of gneiss rocks in all the studied profiles. Radiological hazard, in particular, dose rates, external hazard index, internal hazard index, radium equivalent, annual gonadal dose, effective dose dispensed to various organs of the body were computed to determine the deleterious effects of rocks in the area. The weighted means of annual gonadal dose of 363.98 µSv y-1 and outdoor 0.91 × 10×3 and indoor 1.65 × 10-3 excessive life cancer risks were more than the global average 300 µSv y-1, 0.29 × 10-3 and 1.16 × 10-3. As a result, proper surveillance is required in the area in order to prevent epidemics occurrence in future.

DISTRIBUTION OF RADIONUCLIDES IN RIVER SEDIMENTS OF KATHMANDU VALLEY, NEPAL AND THE EVALUATION OF ASSOCIATED RADIATION HAZARD.

The natural radioactivity in our living environment is mainly due to radionuclides of 40K, 232Th and 238U. We studied the distribution of these radionuclides in the sediment of different rivers and streams throughout the Kathmandu valley. The activity concentrations were determined by using digiBase NaI(TI) gamma-ray spectrometer, and further they were used to calculate radiological hazard indices to estimate the risk associated with the use of these sediments. The average activity concentrations for 40K, 232Th and 238U were found to be 378.54 ± 109.06, 45.95 ± 18.47 and 26.90 ± 9.61 Bq per kg, respectively. The average concentrations and calculated hazard indices have been compared with the respective reported activity concentration in different countries. This study reveals that there is no radiological threat using these local sediments as building materials and for other purposes.