Outdoor Annual Effective Dose Research Articles

Assessment of background radiation levels in selected diagnostic radiology department across Ondo State, Nigeria

The indoor and outdoor ionizing radiation exposure levels were measured in some randomly selected radiological laboratories of some hospitals across Ondo State, Nigeria using a Kindenoo PG - 15 Geiger Muller detector. Measurements were taken in each of the radiological laboratories of the hospitals in two phases: first, when the x-ray machines were energized and second, when the x-ray machines were not energized. The mean indoor and outdoor annual effective doses varied from 20.53±1.07 to 39.12±0.09 and 0.63±0.32 to 1.17±0.45 mSv/y respectively for the first phase in the radiological laboratories and from 1.68±0.04 to 2.26±0.07 and 0.28±0.02 to 0.42±0.02 mSv/y respectively for the second phase. Using statistical tools, a post-hoc test was carried out to test for the statistical significant difference between the indoor and outdoor annual effective dose in the study area. The test showed a significant difference between the indoor and outdoor annual effective dose at the radiological laboratories when the x-ray machine was energized and when the x-ray machine was not energized. Keywords: Indoor radiation exposure, Outdoor radiation exposure, X-ray, Annual effective dose

Natural radioactivity measurement of water and sediment from the historic Ikogosi warm and cold spring, Nigeria

Natural radioactivity measurement and the resultant risk assessment in the water and sediments from the historic Ikogosi warm and cold spring were carried out. A total of 8 samples (4 water and 4 sediment samples) were collected from the Ikogosi spring resort. A sample each was collected from the warm spring, cold spring, meeting point and a sample outside the resort. The samples were thoroughly prepared following the IAEA recommended procedures and analyzed for 40 K, 238 U, and 232 Th using NaI(Tl) detector. The activity concentrations of 40 K, 238 U and 232 Th in water samples range from 40.14 ± 17.83 to 67.59 ± 19.87 Bq L -1 , 8.15 ± 2.84 to 11.14 ± 3.78 Bq L -1 and 5.71 ± 1.32 to 8.24 ± 2.61 Bq L -1 respectively. The activity concentration of sediment samples range from 136.31 ± 17.01 to 246.21 ± 34.93 Bq kg -1 , 17.98 ± 7.64 to 28.32 ± 5.98 Bq kg -1 and 9.57 ± 3.15 to 16.12 ± 3.41 Bq kg -1 respectively. These values compared reasonably well with the worldwide average concentrations of 400 Bq kg –1 , 40 Bq kg –1 , 40 Bq kg –1 for 40 K, 238 U, and 232 Th respectively. The mean absorbed dose rate in air obtained for sediment was 40.33 nGy h –1 , while the annual outdoor effective dose equivalent was 49.46 μSv y -1 , which is lower than the world average of 70 μSv y -1 specified by UNSCEAR for an outdoor effective dose. The total annual effective dose due to ingestion of radionuclides in the water for 3 age groups range from 13.414.87 to 18.856.43 mSv y -1 , 2.751.03 to 5.722.13 mSv y -1 and 2.621.01 to 4.951.43 mSv y -1 for infants (0 – 1 y), children (7 – 12 y) and adult (>17 y) respectively. These values were higher than 1 mSv y -1 recommended by ICRP. Keywords: Natural Radioactivity, Activity concentrations, Cold spring, Ikogosi, Nigeria

Assessment of radiological hazards and effective dose from natural radioactivity in rock samples of Hassan district, Karnataka, India

The natural primordial radionuclide activity concentrations in different types of rock samples in and around Hassan district were measured using gamma spectrometry-based high-purity Germanium detector. The average activity concentration of 226Ra, 232Th, and 40K radionuclides in rock samples varies from 29.4 ± 1.2 to 83.7 ± 1.7, 37.9 ± 1.2 to 198.4 ± 2.2, and 346.1 ± 9.0 to 1024.4 ± 19.4 Bq kg−1 with an average value of 50.9 ± 1.4, 79.6 ± 1.5, and 609.2 ± 12.8 Bq kg−1, respectively. The radiological hazard indices such as radium equivalent activity, gamma index, alpha index, external and internal health hazard indices, absorbed dose rate and annual effective doses were estimated. The average value of radium equivalent activity is less than the criterion limit of 370 Bq kg−1. The average indoor and outdoor annual effective dose values for rock samples are lower than the world average recommended value of 1 mSv y−1. The study concludes that except granite rocks, all the rock samples analyzed are safe when used as construction materials and do not pose any significant radiation hazards.

Measurement of Radioactivity Levels and Health Risks in the Surrounding Soil of Shazand Refinery Complex in Arak, Iran, Using Gamma-Ray Spectrometry Method

ntroduction: The purpose of this study was to measure the radioactivity in the agricultural soil of south-east of Shazand Refinery Complex to determine both reliable baseline data on the radiation level and the radiation dose exposure to the farmers and inhabitants of the studied area. Material and Methods: This study was conducted on 21 soil samples collected from two different lands. Sampling spots in each land were selected for the assessment of specific activities of radionuclides of 226Ra, 232Th, 40K, and137Cs by using high purity germanium detector setup. Standards of International Atomic Energy Agency references material gamma ray uranium, reference gamma-ray thorium, and reference gamma-ray potassium were used for quality control and determining efficiency calibration. All samples were examined for radium equivalent, absorbed gamma dose rate, internal hazard index, external radiation hazard, annual gonadal dose equivalent, indoor and outdoor annual effective dose equivalent, and excess lifetime cancer risk. Results: The specific activities of radionuclides 226Ra, 232Th, 40K, and 137Cs varied from13.12 to 33.03, 11.3 to 35.86, 257.82 to 605.5, and 1.28 to 13.36 Bq/kg, respectively. Moreover, the results of this study were compared with those reported from other countries and worldwide average. Conclusion: Although all samples were polluted by the 137Cs fission product, the measured values were within the global reported safety limits. Therefore, there is no risk for farmers and inhabitants in this region.

Characterization of radiation dose and soil-to-plant transfer factor of natural radionuclides in some cities from south-western Nigeria and its effect on man

Abstract Activity concentrations of natural radionuclides, artificial radiocaesium, and soil-to-plant transfer factor have been evaluated in soils and plant (Amaranthus hybridus) samples from eighteen locations in south-western Nigeria with the aid of a co-axial type, High Purity Germanium (HPGe) detector. The mean specific activities of 40K, 226Ra, 232Th and 137Cs in the soil samples were 393.73 Bq kg−1, 52.91 Bq kg−1, 76.79 Bq kg−1 and 1.44 Bq kg−1, respectively, while the mean specific activities of 40K, 226Ra, and 232Th in plant samples were 3,271.66 Bq kg−1, 25.88 Bq kg−1, and 19.90 Bq kg−1, respectively. 137Cs was found to be below detection limit in the plant samples from all locations of the study area. The radium equivalent concentration, the external and internal hazard indices were estimated, and ranged from 28.47 to 701.53 Bq kg−1, 0.08 to 1.89, and 0.10 to 2.33, with mean values of 191.34 Bq kg−1, 0.52, and 0.66, respectively. The mean soil-to-plant transfer factors for 40K, 226Ra and 232Th were 26.58, 0.62, and 0.39, respectively. The mean absorbed dose and the mean annual outdoor effective dose equivalent in soil samples were 86.44 nGy h−1 and 0.1060 mSv y−1, respectively. The mean annual effective dose equivalent for the study area is higher than the world average (0.07 mSv y−1) and international recommended standards of 0.1 mSv y−1 recommended by World Health Organization (WHO). The excess lifetime cancer risk (ECLR) ranged from 7.35 × 10−5 to 1.36 × 10−3, with a mean of 3.71 × 10−4. This value is higher than the world average of 2.9 × 10−4 reported by United Nations Scientific Committee on the Effects of Atomic Radiation UNSCEAR. The ELCR is a function of environmental geology and 40K has very high soil-to-plant transfer factor compared to other radionuclides in the samples. Regression analysis showed that there was no linearity in the relationship between activity concentration of radionuclides in soil and in plant. This shows that soil-to-plant transfer factor is not a function of soil radioactivity.

Ecological and radiological hazards due to natural radioactivity and heavy metals in soils of some selected mining sites in Nigeria

In this study, the radiological and pollution risks associated with mining of minerals in Nigeria were assessed. Soil samples were collected from a total of 30 illegal mining sites, 10 each from gold, coal and tin mining sites. Thirty soil samples were also collected from unpolluted sites around the mine works. The activity concentrations of the natural radionuclides in the samples were determined using a well calibrated Sodium Iodide Na(Tl) detector. The concentration of Pb, Zn, Cu, Mn, Cr, Cd, Ni and As were determined using an energy dispersive X-ray fluorescence (EDXRF) analyses. The results showed elevated levels of the radionuclides and heavy metals in the mining sites compared to the unpolluted soils. The average outdoor annual effective dose (OAED) obtained were lower than the International Commission on Radiological Protection (ICRP) recommended limit of 1 mSv/y. The results of the geo-accumulation index however showed that the soils of the study areas were strongly contaminated with Pb, Cd and As.

Activity concentration and mapping of radionuclides in Espírito Santo State soils, Brazil

Soils exhibit a wide range of radioactive elements and, therefore, the knowledge of the radioactivity levels that the human being is exposed to is of great importance for Radiological Protection. This study aims to determine the activity concentrations of 40K, 226Ra, and 228Ra in soils of Brazilian state of Espírito Santo, to produce radionuclide concentration distribution maps to understand their occurrence, and to evaluate both the absorbed and effective doses. Sixty six samples were collected, covering all the state area, and analyzed by gamma spectrometry using a Hyperpure Germanium semiconductor detector (HPGe), with relative efficiency of 30%. The activity concentration of 40K varied from 7 to 693 Bq/kg, while 226Ra ranged from 11 to 88 Bq/kg, and 228Ra ranged from 18 to 424 Bq/kg. The absorbed dose, at 1 m above the ground, ranged from 16 to 277 nGy/h. The outdoor annual effective dose ranged from 0.02 to 0.34 mSv/year. About 80% of the samples presented radionuclide content that result in mean annual effective dose above the global. The radionuclide that contributed to the dose was 228Ra, with approximately 78% of the total dose.

Radiation Risk Assessment of Soil in Idomi, Cross River State, Nigeria

In this thesis work, the radiation risk from soil samples in Idomi community located at Yakurr Local Government Area of Cross River State, Nigeria was studied. This was because of an earlier study that revealed the presence of high radioactivity in the area. This study aim to determine the background radiation levels, estimate their effective dose, the mean activity concentrations of the radionuclide and the radiological implications of the radioactivity levels in Idomi. Thirty (30) soil samples were collected and analyzed. The baseline average annual outdoor effective dose, mean activity concentration, gamma absorbed dose and radiological hazard index were studied. Results from this study indicate that three (3) radionuclide namely 40K, 238U and 232Th were present in the soil samples analyzed. The mean activity concentrations of 40K, 238U and 232Th in the soil samples were 506.13±9.30, 41.14±3.59 and 84.52±20.88 Bqkg-1 respectively. The calculated mean external and internal hazard index was 0.62 and 0.71 respectively. The calculated mean gamma index was 0.86. The Raeq in the soil samples was 227.34 Bqkg-1. The calculated absorbed gamma dose from the sample was 110.31nGy-1 and a mean annual outdoor effective dose of 1.35mSvy-1. Compared with global average values of 10-200nGyh-1, 2.4 mSvy-1and Raeq of 370BqKg-1 they can be said to be within the normal range. From this study, the chances of occurrence of health effects from exposure to natural terrestrial gamma radiation in Idomi can be said to be low. This may be possible if the baseline levels obtained from this study can be kept constant by keeping the environment free of radioactive pollution.

Assessment of nuclear radiation pollution in uranium mining-impacted soil

Activities associated with mining of uranium have generated significant quantities of waste materials containing uranium and other toxic metals. A qualitative and quantitative study was performed to assess the situation of nuclear pollution resulting from waste of drilling and exploration left on the surface layer of soil surrounding the abandoned uranium mine hole located in the southern of Najaf province in Iraq state. To measure the specific activity, twenty five surface soil samples were collected, prepared and analyzed by using gamma- ray spectrometer based on high counting efficiency NaI(Tl) scintillation detector. The results showed that the specific activities in Bq/kg are 37.31 to 1112.47 with mean of 268.16, 0.28 to 18.57 with mean of 6.68 and 132.25 to 678.33 with mean of 277.49 for 238U, 232Th and 40K respectively. Based on these values, radium equivalent activity in Bq/kg and absorbed dose rate one meter above the ground surface nGy/h were calculated and found to be vary 52.72 to 1189.84 and from 25.02 to 553.01. The indoor and outdoor annual effective dose rate in mSv/y ranged from 0.12 to 2.71 and from 0.03 to 0.67 respectively. To evaluate the dangerous of the study area, the external (Hex) and internal (Hin) hazard indexes are calculated and found to be ranged 0.14 to 3.21 and from 0.24 to 6.22. For the purpose of assessing the seriousness of the study area, results were compared with the world wide average. This comparison indicated that the study area is not safe from the radiological protection point view.

Integrating radon and thoron flux data with gamma radiation mapping in radon-prone areas. The case of volcanic outcrops in a highly-urbanized city (Roma, Italy)

An integration of laboratory radon and thoron exhalation data with gamma radiation mapping is applied to assess the geogenic radon and the exposure of people to natural radiation in a highly-urbanized city (Roma, Italy). The study area is a protected territory where ignimbrites from Colli Albani volcano and alluvial sediments largely crop out. A map of total gamma radiation, a gamma transect across Caffarella valley and 9 vertical gamma profiles have been carried out, showing that the main control of gamma levels is, of course, the lithological nature, without neglecting the simultaneous effect of other parameters such as slope morphology, erosion/weathering processes, occurrence of sinkholes or underground tunnels. The surveys allowed to distinguish the medians of ignimbrites (from 816 ± 16 cps to 936 ± 19 cps) from that of alluvial materials (611 ± 14) cps), but showed also that alluvial sediments with anomalously high radioactivity (769 ± 14 cps) can be locally recognized, providing valuable information on the interaction between sedimentation and erosion in fluvial valleys. Total gamma activity was converted into absorbed gamma dose rate ranging from 0.33 to 0.38 μSv/hr. Outdoor Annual Effective Dose Equivalents were also estimated between 0.58 and 0.67 mSv y−1.Laboratory radon and thoron exhalation rates of collected material are positively correlated with gamma radiation. Volcanic and alluvial sediments are well-discriminated. The correlation between the two variables is evident, but not robust because of the variable concentration of 40 K, which is not contributing to radon and thoron exhalation rates. Anomalous data of soil samples located at the foot of a slope can be interpreted as due to reworking and accumulation processes. Similar gamma radiation data documents analogous concentration of radon and thoron parent-nuclides, but coexisting different radon and thoron exhalation rates provides an additional information on different grain size distributions which can be considered as a proxy for soil gas permeability.The integration of gamma mapping and radon and thoron exhalation measurements is a very useful tool to assess people exposure to natural radiation, in terms of dose rates and potential indoor radon. Gamma mapping, which provides data on the radiation source (the bedrock) is fast and not expensive. It allows to obtain very detailed pictures of a study area, but it needs to be combined with laboratory determination of radon and thoron release in order to definitely and correctly interpret variations of gamma signal. Furthermore, laboratory determination of soil radon exhalation gives information on the release of radon and is a good proxy for soil gas permeability. It has the great advantage over in-situ measurements of gas flow not to be influenced by seasonal pedoclimatic parameters and is affected by lower analytical uncertainties. These data are thus reproducible and precise and can be used to estimate potential radon hazard, which is the main source of exposure and thus the most important parameter for human protection from environmental radioactivity.

Naturally occurring radioactive material and risk assessment of tailings of polymetallic and Ra/U mines from legacy sites

Old mine tailings from Northern and Central Portugal were studied in order to perform a radiological and chemical characterization. The evaluation of massic activity of natural radionuclides and concentrations in tailings of polymetallic and Ra/U mines was performed by gamma spectrometry and neutron activation analysis. Iron speciation was carried out by Mössbauer spectroscopy. In polymetallic tailings with physical ore processing (Cumieira and Verdes - exploited for Sn, Nb-Ta) higher contents of Th, 228Ra and 226Ra in the coarser materials occur, probably due to their presence in host rock and ore fragments. In finer tailings, washing may explain the lower 226Ra and 210Pb massic activity. In tailings with physical/chemical ore processing (Covas - exploited for W and Sn) high U contents and a tendency for higher 226Ra and 210Pb massic activity in the fine materials is observed, probably due to their incorporation in nano-sized particles of iron oxides. A high variation of the 210Pb/226Ra ratio occurs in polymetallic tailings; a deficit of 210Pb can be observed particularly in deposits of settling tanks drained from dumps of chemically treated ore. In Ervideira-Mestras tailings (Ra/U exploitation) where no ore process in situ was performed, a near equilibrium between 210Pb and 226Ra occurs. Dose risk assessment was carried out by calculating external outdoor Annual Effective Dose Rate; the dose rates in air due to terrestrial gamma radiation are low for the polymetallic tailings (<47 nGy/h), and higher for tailings of Ra/U (up to 4130 nGy/h), in the worst scenario.

Assessment of Environmental Radioactivity and Health Hazard in Soil, Water, and Stone Samples in Siverek Town of Sanliurfa Province in Southeastern Turkey

Human life depends on water and soil where our food mostly needs to be grown. Let us not forget the nature and rocks that we are surrounded in terms of structural base. For that reason, it’s crucial to determine their radioactivity level not just to help mapping the country’s radiation background measurements, but to assess people’s safety and protection. Especially, the International Atomic Energy Agency (IAEA), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), World Health Organization (WHO), or the International Commission on Radiological Protection (ICRP) develop safety standards to protect the health and to minimize the danger for people’s life before anything happens. In this specific study, the most densely populated county, called Siverek, in the region of Sanliurfa municipality was selected. For the analysis of soil and rock, respectively 11 and 7 distinctive locations were considered to determine the activity levels in Harran University laboratory. As to water samples, only two samples were proceeded to detect total alpha and beta activities by Cekmece Nuclear Research and Education Centre (CNAEM) by Turkish Atomic Energy Agency (TAEK).With regard to analysis tools, Ortec brand NaI(Tl) scintillation detector was used to detect any activity based on naturally occurring radioactive materials (NORM), such as 238U, 232Th, and 40K elements in soil and stone samples with the help of digibase MCA system. For water activity level investigation, low-level activity measurement system of LB770-PC with 10 channels, were used.As a result, it’s expected to find the levels of the most encountered activity units; such as Radium equivalent dose, indoor and outdoor external absorbed doses, internal and external hazard indices, indoor and outdoor annual effective doses, indoor and outdoor excess life-time cancer risks lower than the values that some organizations stated in their literature.

Assessment Of Radiological Consequence Of Radioactivity In Monazite Beach Sand In South West Coastal Region In Southern India

Abstract The natural radionuclide ( 226Ra, 232Th and 40K) contents of sand samples at various locations in Sakthikulangara area in the south west coastal region of Kerala state have been determined using NaI(Tl) based gamma spectrometric measurement method and radiation hazard indices in the study area are evaluated. The specific activities of the radionuclides were found to vary from below detectable level to 32.38 BqKg-1, 34.77 BqKg-1 to 229.30 BqKg-1 and 20.76 BqKg-1 to 88.39 BqKg-1, respectively for 226Ra, 232Th and 40K. The radium equivalent activity (Raeq) was quite less than the recommended limit of 370BqKg-1. The radiological parameters such as internal and external hazard indices, absorbed dose rate, indoor and outdoor annual effective dose, alpha index and representative level index were also determined from the estimated value of the specific activity of 226Ra, 232Th and40K.

Measurements of natural radioactivity in soil samples collected in the Kampinoski National Park

In this article are presented the results of measurements of natural radioactivity in twelve soil samples from the Kampinoski National Park by using high purity germanium detector (HPGe). The average values of the natural radionuclides40K,226Ra and228Ac concentrations in the soil samples are 8.54, 6.65 and 206 Bq/kg respectively. Additionally radiation hazard indices were calculated to evaluate the radiological risk for the public and environment. The results show that the mean values of radium equivalent activity (Raeq) and gamma absorbed dose rate (D) in the air, outdoor annual effective dose equivalent (Eout), and representative level index (Iγ) for analyzed samples were lower than the limit recommended by the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). This study is the first to evaluate the radiological impacts in the investigation area.

Assessment of Radiological Hazard Indices from Exposures to Background Ionizing Radiation Measurements in South-South Nigeria

Radioactivity in the environment from sources of natural and human activities resulting in planned, emergency and existing exposure to human population, environment and other biota has led to growing apprehensions in Nigeria and the world. The existing exposure situations mainly from natural radionuclides, present in the earth crust from creation emits background ionizing radiation leading to gamma dose exposures. The objective of this study was to assess the background ionizing radiation and associated radiological hazard indices in Itu, Nigeria located at 5010’0” N 7059’0” E, and establish an eco-radiological baseline data prior to the construction of any nuclear fission reaction facility in the area. A systematic random method of measurement was employed within demarcated monitoring zones of entire geological map of Itu, Nigeria. The global positioning system finder (GARMIN Etrex 10) was used for data point location, while RDS-31S/R Multi-purpose survey meter was used for dose rate measurement. The background ionizing radiation measurement obtained ranged from 0.041 ± 0.002 - 0.045 ± 0.002 µSv/hr with overall mean of 0.042 ± 002 µSv/hr, which was lower than the world mean of 0.2 µSv/hr. Radiological hazard indices arising from the background ionizing radiation measurement were also evaluated. The mean estimated Gamma Dose Rate was 9.312 nGy/hr, the terrestrial outdoor Annual Effective Dose Rate arising from gamma was 6.83 mSv/yr, that of indoor was 21.85 mSv/yr and Excess Life Cancer Risk was 0.05 × 10-3. The mean evaluated radiological hazard indices were found to be below admissible limits, and thus poses no significant radiological health threat to the populace. Therefore, the assessment demonstrates that there is no elevated level of dose rate, which is makes it safe for human habitation, but care should be taken to avoid increase radiation level from human activities. It is recommended that constant radiological monitoring be encourage, and the data considered as radiological baseline in Itu, Nigeria.

Comparison of Gamma Dose Levels in Assessed by Various Methods

Abstract Indoor and outdoor gamma dose rates were evaluated along the coastal regions of Thangasherry, Kollam district, Kerala through direct measurements using a GM based gamma dose survey meter, time integrated measurement using CaSO4:Dy based thermo luminescent dosimeters (TLDs) and theoretically gamma spectrometry of soil samples. The mean values of indoor and outdoor Annual Effective dose rates observed were 1.26±1 mSv/yr and 0.378±0.08 mSv/yr, respectively with an indoor to outdoor dose ratio of 0.86. The radioactivity content in the soil samples, the absorbed dose rate, annual effective dose equivalent, radium equivalent activity, internal and external hazard indices , the representative gamma index and alpha index (Igamma and Ialpha), the annual gonad dose equivalent (AGDE) and the excess lifetime cancer risk (ELCR) were determined and compared with recommended values. Correlation study showed that the dose estimated from the TLDs is better correlated with that measured directly using the portable survey meter. The results of natural radioactivity levels in the soil samples has been compared with the levels reported in other Indian cities as well as other parts of the world.

Environmental radioactivity levels in agricultural soil and wheat grains collected from wheat-farming lands of Koya district, Kurdistan region-Iraq

The purpose of this study is to determine the activity concentration levels of radionuclides of226Ra,232Th,40K, and137Cs in soil and wheat grain samples. A total of 72 samples of soil and wheat grains were collected in the study area. Measurements were performed using a gamma-ray spectroscopic system based on high purity germanium detector. The average activity concentrations of226Ra,232Th, and40K in soil samples were found to be 14.7 ± 0.2 Bq/kg, 19.9 ± 0.5 Bq/kg, and 329 ± 5.4 Bq/kg, respectively, and for the measured wheat grain samples their values were found to be 0.4 ± 0.09 Bq/kg for226Ra, 0.36 ± 0.1 Bq/kg for228Ra, and 109.2 ± 2.2 Bq/kg for40K. The calculated mean values of radium equivalent activity Raeq, outdoor absorbed dose rate Dout, and outdoor annual effective dose rate of the soil samples were found to be 68.55 Bq/kg, 32.5 nGy/h, and 0.039 mSv/year, respectively. Moreover, the radionuclide transfer factor from soil-to-wheat grains of naturally occurring radionuclides were found in this order40K > 226Ra > 228Ra.

Measurement of Radioactivity And Assessment of Radiological Hazard of Tea Samples Collected From Local Market In Bangladesh

The activity concentrations of natural radionuclides and radiological hazard indices in eleven tea samples collected from local market in Bangladesh have been analyzed by using High Purity Germanium (HPGe) Detector. The average activity concentrations of 226Ra, 232Th and 40K in tea samples have been found to be 21.21±14.04, 32.43±7.48 and 93.47 ± 43.94 Bqkg-1 respectively. The calculated absorbed dose rates due to these radioactive nuclides in tea samples have been found to vary from 26.24 nGyh-1 to 37.95 nGyh-1 and average value was 33.28 nGyh-1. The estimated outdoor annual effective dose rates varied from 38.64 µSvy-1 to 55.89 µSvy-1 with the mean value of 49.02 µSvy-1 which is less than the world average value of 1000 µSvy-1. The values of radium equivalent activity in all samples are less than the permissible maximum value of the radium equivalent activity which is 370 Bqkg-1 according to UNSCEAR 2000 report. The values of external and internal hazard indices for different samples varied from 0.16 to 0.23 with the average value of 0.20 and from 0.21 to 0.29 with an average of 0.26. The value of this index must be less than unity in order to keep the radiation hazard insignificant. It was also found that there is no artificial radionuclide (for example 137Cs) in any of the samples. The data generated in this study will provide baseline radiometric values for natural and artificial radioactivity in tea samples in Bangladesh.&#x0D; Journal of Bangladesh Academy of Sciences, Vol. 42, No. 2, 171-176, 2018

Natural radionuclide survey in the coastal strip of the 290 Ramsar site, Uruguay

An initial on-going survey of the activity concentrations of 226Ra, 232Th and 40K for sand samples collected within the coastal strip of 290 Ramsar site evaluated the external hazard index, the outdoor annual effective dose equivalent and the radium equivalent activity, to elucidate potential risks for the resident inhabitants. The range of mean activity concentrations in the whole area for 226Ra, 232Th and 40K were between 4.12 ± 0.26 and 48.3 ± 1.4, 5.47 ± 0.55 and 194 ± 13, 77.7 ± 4.2 and 445 ± 18 Bq kg−1, respectively. The Barra de Valizas–Aguas Dulces region had the highest activity concentrations of 226Ra and 232Th. The annual effective dose equivalent for this region was higher than the mean worldwide value, whereas it is lower than the recommended values for public exposure.

Determination of natural radioactivity in soil samples around gold mining area in Khamkeut district, Bolikhamxay Province, Laos using gamma ray spectrometer with NaI(Tl) detector

This paper presented the method of determining the radioactivity of 40K, 226Ra and 232Th in soil samples by gamma-ray spectrometer using NaI (Tl) scintillation detector. The radioactivity of each isotope is calculated based on the net count rate in the energy window characteristic for the 40K, 226Ra and 232Th radioisotopes respectively. We have determined activity concentrations of the natural radionuclides 226Ra,232Th and 40K in 15 soil samples collected around gold mines of Khamkeut district, Bolikhamxay Province, Laos. The average activity concentrations of the natural radionuclides 226Ra, 232Th and 40K are 46.58 ± 7.36 , 71.19 ± 5.42 and 574.62 ± 25.02 Bq.kg-1, respectively. The average activity concentrations of 226Ra and 232Th in this work are higher than those of Bolikhamxay Province, Laos and the world average values. The estimated average outdoor annual effective dose (E) and radium equivalent actitvity (Raeq) are 0.10 ± 0.004 mSv.yr-1 and 192.64 ± 16.12 Bq.kg-1, respectively.