Natural Radiation Dose Research Articles

Natural Radiation Dose and Geomagnetic Effect

Earth keeps getting bombarded by high-energy particles that originate in the outer space and in Sun. Cosmic radiation in Earth’s atmosphere consists of a photon and directly ionizing component and a neutron component. Charged particles of cosmic radiation are deflected by the geomagnetic field that is more expressed at the equator than near the poles. Photon radiation was measured by Radiameter ESM FH 40G-L10 at 26 main meteorological stations in all parts of Croatia. The correlation between the photon dose rate and latitude was examined, as well as multiple correlations for the photon dose, latitude and altitude. The obtained positive correlation coefficients were statistically significant. The neutron component of the cosmic radiation was measured by series of nuclear track-etched detectors, at the same meteorological stations during one year period. The dependence of the neutron dose rate on the altitude was found and the associated equation of the linear regression was derived. Relation between the values of neutron dose N and altitude h, showed significant dependence of the neutron dose on altitude. However, the correlation of neutron dose and geographic (geomagnetic) latitude was not statistically significant, probably due to a small range of geographic latitudes for the measuring stations in Croatia.

Determination of atmospheric concentration of beryllium-7 at ground level

Atmospheric concentration of beryllium-7 (7Be) at ground level was measured from September 2012 to October 2013 in San Carlos de Bariloche, Argentina, using a HPV-5300AFC brushless, automatic flow control outdoor high volume air sampler for continuous use, and 8”×10” 0.8 microns fiberglass filters. The activity of 7Be was determined on a high-purity germanium (HPGe) detector (relative efficiency 12.3%) by standard gamma spectrometry. The average value found was 4.1 ± 0.1 mBq/m3. Seasonal changes in the atmospheric concentration of 7Be were compared with other environmental variables (temperature, humidity, precipitations, and air kerma rate), and correlation, both positive and negative, was observed as expected. Measurements were carried out following the Radiological Environmental Monitoring Programme at Bariloche Atomic Centre. The aim of the study was to determine atmospheric concentration of 7Be at ground level and to correlate its seasonal changes with environmental variables. Air samplers and environmental dosemeter locations were far away from buildings and any other thing that could influence or alter the measurements. Pearson's correlation coefficient was calculated to evaluate the relation between atmospheric 7Be concentration and environmental variables of interest. These changes in 7Be concentration can be attributed to the variations and dynamic of air exchange between the stratosphere and the troposphere and to the variations of the tropopause height. To fully understand and correctly interpret the meaning of these seasonal variations in the concentrations of atmospheric 7Be, active atmospheric processes must be taken into account. According to the measurements carried out, contribution of 7Be concentration to the natural background radiation dose is negligible.

Variations of radon concentration in the atmosphere. Gamma dose rate

The purposes of research were following: observation and interpretation of variations of radon concentration in the atmosphere - vertical, seasonal, spatial and analysis of relation between average annual radon concentration and ground natural radiation and gamma dose rate. Moreover we wanted to check the occurrence of radon density currents and the possibility of radon accumulation at the foot of the spoil tip.The surveys were carried out in Okrzeszyn (SW Poland) in the area of the spoil tip formed during uranium mining that took place in 60's of 20th century. The measurements were carried out in 20 measurements points at three heights: 0.2 m, 1 m and 2 m a.g.l. using SSNTD LR-115. The survey lasted one year and detectors were exchanged at the beginning of every season. Uranium eU (ppm), thorium eTh (ppm) and potassium K (%) contents were measured using gamma ray spectrometer Exploranium RS-230, ambient gamma dose rate using radiometer RK-100.The average radon concentration on this area was 52.8 Bq m-3. The highest radon concentrations were noted during autumn and the lowest during winter. We observed vertical variations of radon concentration. Radon concentrations decreased with increase of height above ground level. The decrease of radon with increase of height a.g.l. had logarithmic character. Spatial variations of radon concentrations did not indicate the occurrence of radon density currents and accumulation of radon at the foot of the spoil tip.The analysis of relation between average radon concentrations and ground natural radiation (uranium and thorium content) or gamma dose rate revealed positive relation between those parameters. On the base of results mentioned above we suggested that gamma spectrometry measurements or even cheaper and simpler ambient gamma dose rate measurements can be a useful tool in determining radon prone areas. This should be confirmed by additional research.

스키장의 자연방사선량 측정(경기도 지역을 중심으로)

레저생활의 급증으로 인하여 스키장 사용 인구가 급격히 증가하고 있다. 스키장은 직접적으로 자연광이나 우주선을 받을 확률이 높다. 왜냐하면 고도가 존재하는 산에 위치하기 때문이다. 일반적으로 고도가 높아질수록 자연방사선량이 증가한다는 사실은 널리 알려져 있다. 하지만 아직까지 스키장 고도에 관한 자연방사선량은 보고되지 않았다. 국내에는 다양한 스키장이 존재를 하지만 이번논문에서는 경기도 지역의 스키장4곳을 선정하여 고도에 따른 자연방사선량을 측정하였다. 결과적으로 스키장은 고도가 낮은 일반생활 지역에서보다는 방사선량보다 조금 많은 방사선량이 측정되었다. 우려할 수준은 아니지만 스키장 이용 시에는 반드시 스키 장비인 고글이나 다양한 스키 웨어(고글, 마스크, 헬멧)를 착용하여 자연방사선량을 보호한다면 환경방사선으로부터 안전하게 스키를 즐길 수 있을 것이다. With the increase in leisure life, the population of ski resorts is rapidly increasing. The activity at the ski resort is likely to receive a direct chance of natural sunlight or space ray. Because it is located in the mountains where altitude exists. As a general rule, it is widely known that the higher the elevation rate, the more increasing the natural radiation dose. However, the natural radiation dose rate for the ski slopes has not been reported yet. Various ski resorts exist in Korea, but this study had chose 4 ski resorts to measure the natural dose of natural radiation. As a result, the natural radiation dose for the ski slope was measured at a relatively high dose of ordinary living areas. However, the level of natural radiation dose was not worrisome. It is recommended to wear ski wear or goggles to minimize natural radiation exposure at the ski slopes.

Mapping of natural gamma radiation (NGR) dose rate distribution in tin mining areas of Jos Plateau, Nigeria

An extensive study was conducted to measure the natural gamma radiation (NGR) dose rates for the tin mining areas of Jos Plateau with an objective to establish a reference data record on the levels and distribution of natural background gamma radiation. The measurement was carried out using a portable NaI(Tl) scintillation survey meter. The results obtained, varied significantly for different soil types and for geological features of the study area. NGR dose rates values ranged between 40 nGy h−1 measured on Ferric Luvisols–Ferric Luvisols (S13) soil type, underlain by geological formation G7 (sandstone, clay and shale) and 1265 nGy h−1 recorded on, Haplic Acrisols (S27), underlain by geological formation G8 (Younger granites) with overall mean value of 250 nGy h−1. This is by a factor of four higher than the reported world average value of 59 nGy h−1. Mean indoor and outdoor annual effective dose for the public was estimated to be 1.2 and 0.31 mSv/y, respectively. An isodose map for the distribution and exposure rate due to natural sources radiation for the study area was also plotted using ArcGis software. The data here presented can use to prepare a national radiological map for the country.

Natural radiation dose at various geologies in Korea

Natural radiation dose at various geologies in Korea

The surrounding radiation dose of iodine-125 seeds on normal larynx tissue in rabbits

Objective:To monitor the change of the radiation dose of the rabbits which were implanted rasioactive 125I seed into the normal laryngeal tiseue at different time,and to evaluate the safety of radiation protection. Method:Sixty New Zwaland rabbits, weighing 2.15-2.30 kg，were randomly divided into 5 groups:7 d,1month,2 month,4 month group and the control group, 12 rabbits in each group Iodine-125 of 0.8 mCi were implanted into the right side of the first trachea ring. At the different time and different distance, the surrounding radiation dose was measured after 4 months of implanting. The results were analyzed in statistics. Result:With the increase of the distance and the prolong of the time, the radiation dose was decreasing，and with the increase of distance,the radiation dose decreased slowly. At the site of 1 meter from the seeds, the detected dose is close to the natural background radiation dose. Conclusion:The clinical application of radioactive 125I seed interstitial implant is easy to protected,the surrounding close contacts is satety.

Contributions of Various Radiological Sources to Background in a Suburban Environment.

This work is a brief overview and comparison of dose rates stemming from both indoor and outdoor natural background radiation and household objects within a suburban environment in North Carolina. Combined gamma and beta dose rates were taken from indoor objects that ranged from the potassium in fruit to the americium in smoke detectors. For outdoor measurements, various height and time data samples were collected to show fluctuations in dose rate due to temperature inversion and geometric attenuation. Although each sample tested proved to have a statistically significant increase over background using Students t-test, no sample proved to be more than a minor increase in natural radiation dose. The relative contributions from natural radioactivity such as potassium in foods and common household items are shown to be easily distinguished from background using standard handheld instrumentation when applied in a systematic, methodological manner.

MEASUREMENT OF RADON, THORON AND THEIR PROGENY CONCENTRATIONS IN THE DWELLINGS OF PAURI GARHWAL, UTTARAKHAND, INDIA.

It is well known that inhalation of radon, thoron and their progeny contributes more than 50 % of natural background radiation dose to human being. The time-integrated passive measurements of radon, thoron and their progeny concentrations were carried out in the dwellings of Pauri Garhwal, Uttarakhand, India. The measurements of radon and thoron concentrations were performed by LR-115 detector-based single-entry pin-hole dosemeter, while for the measurement of progeny concentrations, LR-115 deposition-based direct radon and thoron progeny sensors technique was used. The experimental techniques and results obtained are discussed in detail.

Radiation Exposure Related to Computed Tomography: Do We Need to be Unfazed, Scared or Very Scared?

Short abstract to the handouts In this presentation we will try to answer following questions: (1) what is the magnitude of medical radiation exposure compared to other EU countries, (2) how is medical exposure measured (especially in computed tomography (CT), (3) what are the involved stochastic health effects? A recent EU report (radiation protection no. 180, 2014) estimated the average effective dose (E) from medical exposure in Belgium to be around 2 mSv per year, which equals more or less the annual dose of natural background radiation. This is the highest value in the EU and can be explained by the high frequency of radiology procedures: with about 250 procedures per 1000 of population, Belgium has the highest frequency of procedures. Most EU countries are between 100 and 200 procedures per 1000 population. We learn that the assessment of effective dose from medical exposure—and especially CT—can be problematic due to the large heterogenic exposure geometry. We describe three methods to estimate organ and effective dose which have increasing level of complexity and cost: (1) generic Dose Length Product (DLP) to E coefficients, computer simulations with a (2) mathematical and a (3) detailed voxel model which is based on the actual patient images. Radiation effects from low doses (< 100 mSv) remain a debated issue. There are different models reported to extrapolate the effects which are observed at mediocre (between 100–2500 mSv) doses towards zero dose. The model which is currently the most defended is the linear no threshold (LNT) hypothesis. Population cancer risk estimates from medical exposures are typically based on these models. More recently, direct epidemiological studies are also reported on cancer risk in people exposed to CT in childhood or adolescence. However, we should acknowledge that our current knowledge on low dose effects remains inconclusive and we should avoid giving absolute estimates of cancer induction from medical exposure. Even patient dose estimations have many inherent limitations. Automated patient dose registration systems might help to improve accuracy in the future. Above all, the alara principle must prevail: doses should be kept as low as reasonably achievable by continuously optimizing scan protocols and by implementing new technological advantages.

Natural Radioactivity and Radiation Dose Estimation in Various Water Samples in Abua/Odua Area, Rivers State, Nigeria

Natural Radioactivity and Radiation Dose Estimation in Various Water Samples in Abua/Odua Area, Rivers State, Nigeria

Annual individual hygienic assessment of natural exposure doses of the Altai territory model areas population

The goal is to determine ionizing radiation natural sources exposure regularities of Altai Territory model areas population. The materials and methods. 11376 radon measurements, 1247 gamma radiation meas-urements in an open area and in residential and office buildings were performed, selection of 189 drinking water tests was carried out. Results. Complex radiation and hygienic examination of the region with the most large municipalities number with model areas allocation was conducted. The assessment of the Altai Territory population’s individual annual radiation doses from natural radionuclides has revealed a number of the regularities depending on the terrain’s ecological and geographical type. Following the research results, ranging the region territories taking into account of annual effective doses of the population from natural sources for 2009-2015 was carried out. The annual individual effective dose of the Altai Territory upland areas population presented by the highest values and ranges from 7.36 mSv / year to 8.19 mSv / year. Foothill regions of Altai and in Salair ridge are characterized by increased population exposure from natural sources. Here the dose ranges from 5.09 mSv / year to 6.22 mSv / year. Steppe and forest-steppe territories are characterized by the lowest level of the natural radiation which is ranging from 3.23 mSv / year to 4.11 mSv / year, that doesn’t exceed the all-Russian levels. Most of the hygienic radon equivalent equilibrium volume activity standards exceedances were registered in mountain and foothill areas buildings. A number of radon anomalies is revealed also in steppe areas. Med exceedances ranged from 203 ± 17.8 Bq / m3 to 480 ± 37.9 Bq / m3. Given the fact that most of these buildings belong to the administrative or educational institutions with an eight-hour working day, the dose of radiation for people there can be up to 10 mSv / year. Conclusion. Spreading of individual annual effective dose of the Altai Territory population showed that five regions of the model areas are converted into three main groups depending on the natural radiation dose due primarily radon equivalent equilibrium volume activity and depends mostly on the eco-geographical terrain type.

NATURAL RADIOACTIVITY IN MAJOR RIVERS OF KELANTAN STATE, MALAYSIA

Assessment of natural radionuclides (238U, 232Th, and 40K) and terrestrial gamma radiation dose rates (TGRD) in major rivers of Kelantan states, Malaysia were conducted. Measurements were carried out using a portable [NaI(TI)] micro roentgen (µR) survey meter and inductively coupled plasma mass spectrometer (ICP-MS) for in situ TGRD and the activity concentrations of 238U, 232Th, and 40K in water samples, respectively. The mean TGRD was found to be 312.98 nGy h-1 and from water samples analyzed, the mean activity concentrations of 238U, 232Th, and 40K was found to be 13.31 mBq L-1, 4.39 mBq L-1 and 1118.72 mBq L-1 which were about 3 times and slightly higher than the world average values of 5 mBq L-1 and 3 mBq L-1 respectively.

Radioactivity of Natural Nuclides (40K, 238U, 232Th, 226Ra) in Coals from Eastern Yunnan, China

The naturally occurring primordial radionuclides in coals might exhibit high radioactivity, and can be exported to the surrounding environment during coal combustion. In this study, nine coal samples were collected from eastern Yunnan coal deposits, China, aiming at characterizing the overall radioactivity of some typical nuclides (i.e., 40K, 238U, 232Th, 226Ra) and assessing their ecological impact. The mean activity concentrations of 238U, 232Th, 40K and 226Ra are 63.86 (17.70–92.30 Bq· kg-1), 23.76 (11.10–37.10 Bq· kg-1), 96.84 (30.60–229.30 Bq· kg-1) and 28.09 Bq·kg-1 (3.10–61.80 Bq·kg-1), respectively. Both 238U and 232Th have high correlations with ash yield of coals, suggesting their inorganic origins. The overall environmental effect of natural radionuclides in studied coals is considered to be negligible, as assessed by related indexes (i.e., radium equivalent activity, air-adsorbed dose rate, annual effective dose, and external hazard index). However, the absorbed dose rates values are higher than the average value of global primordial radiation and the Chinese natural gamma radiation dose rate.

A study of the natural radioactivity and radon exhalation rate in some cements used in India and its radiological significance

The presence of natural radioactivity and radon exhalation from building materials contribute to the radiation dose received by human. So, it is essential to evaluate the activity levels of the primordial radionuclides (238U, 226Ra, 232Th and 40K) present in the building materials for the assessment of natural radiation dose. Cement is one of the major component of the building materials and is used on a large scale. In the present study, the commercially available cement samples of fifteen different brands were used to study the radon exhalation rate and activity concentration of 238U, 226Ra, 232Th and 40K nuclides. The radon exhalation rate was measured using the can technique, while the concentration of radionuclides content was determined by using gamma ray spectroscopy. The radon exhalation rate from different brands of cements was found in the range from 1.56 to 13.1 mBqkg−1h−1 with a mean value of 5.27 mBqkg−1h−1. The specific activity of uranium was found in the range 45.3–218.9 Bqkg−1 with a mean value of 111.2 Bqkg−1; 226Ra from 20.3 to 60.1 Bqkg−1 with a mean value of 35.8 Bqkg−1; 232Th from 18.8 to 60.1 Bqkg−1 with a mean value of 33.2 Bqkg−1 and 40K varied from 160.9 to 248.1 Bqkg−1 with a mean value of 199.1 Bqkg−1. The radiological parameters – radium equivalent activity, absorbed dose rate, annual effective dose, external hazard index, internal hazard index, gamma activity index and alpha index were also evaluated to assess the potential radiological hazard associated with these cement samples. Correlation coefficients for the different radionuclides have been evaluated and studied.

Assessment of Natural Radioactivity Levels and Radiation Dose Rate in Some Soil Samples from Historical Area, AL-RAKKAH, Saudi Arabia

This study aims to determine the activity concentrations of naturally occurring, technically-enhanced levels of radiation and the gamma absorbed dose rates in soil samples collected across the land scape of historical area which discovered in east of Saudi Arabia at 2009 G, Called AL- RAKKAH. By using an HPGe detector gamma-ray spectrometer, the activity concentrations of 226Ra 232Th and 40K were found in surface soil samples ranged from 17. 4 ± 1.2 Bq/kg to 28.3 ± 2.3 Bq/kg with an average value of 23 ± 1.6 Bq/kg, ranging from 1.1 ± 1.8 Bq/kg to 81.0 ± 1.7 Bq/kg with the average value 20 ± 1.4 Bq/kg and from 218 ± 11 Bq/kg to 255 ± 18 Bq/kg, with the mean value of 233 ± 12 Bq/kg respectively. The mean radium equivalent (Raeq) and outdoor radiation hazard index (Hex) for the area under study were determined as 69.52 Bq/kg and 0.16 respectively. The total absorbed dose rate due to three primordial radionuclides lies in the range of 17.74 - 72.24 nGy·h-1 with a mean of 32.69 nGy·h-1, which yields total annual effective dose of 0.37 mSv·y-1. The measured values are comparable with other global radioactivity measurements and are found to be safe for public and environment. The baseline data of this type will almost certainly be of importance in making estimations of population exposure.

Evaluation of the natural gamma radiation level in residential zones and determination of annual effective exposure dose in the residents of Hamadan province, Iran, 2012

Background and Aim: Human is always exposed to natural background ionizing radiation which may have harmful effects; therefore, measurement of the natural background radiation is important. In this study, was measured the dose of effective natural background gamma radiation in indoor residential zones of Hamadan Province. Material and Methods: In this cross-sectional study, we selected four stations along the main geographic directions and one in the center of city for measurement of the indoor dose rate in each of the cities in Hamadan Province. Based on the household numbers, some houses were selected randomly in every station and natural background indoor dose was measured by using RDS-110 survey meter. Then, using the results of our previous study about measuring the level of outdoor natural gamma radiation in this province, we determined the level of annual effective exposure dose from natural gamma radiation in Hamadan residents. Results: In Hamadan province cities, maximum and minimum indoor natural background radiation (gamma ray) belonged to Razan City (1.41±0.079 mSv) and Asadabad City (0.955±0.044 mSv), respectively. Mean annual equivalent indoor dose in Hamadan Province was 1.20±0.070 mSv. Also the maximum indoor natural background radiation dose (gamma ray) in the buildings with the age of more and less than 25 years were 1.42±0.219 mSv and 1.44±0.149 mSv, respectively. According to the results of this study and our previous study about outdoor gamma natural background radiation, the annual effective dose in Hamadan Province residents was 0.83 mSv. Conclusion: According to the results of this study, it seems that annual effective equivalent dose due to indoor gamma radiation in Hamadan Province exceeded the mean external exposure amount reported by UNSCEAR (0.5 mSv). Also the annual effective dose due to gamma background radiation in Hamadan Province residents is 0.83 mSv, which is higher than the global average (0.48 mSv) reported by UNSCEAR - 2000. Therefore epidemiological studies to assess the prevalence of chronic diseases associated with natural radiation exposure among Hamadan Province residents are recommended.

Natural Radioactivity Measurements and Radiation Dose Estimation in Some Sedimentary Rock Samples in Turkey

The natural radioactivity existed since creation of the universe due to the long life time of some radionuclides. This natural radioactivity is caused byγ-radiation originating from the uranium and thorium series and40K. In this study, the gamma radiation has been measured to determine natural radioactivity of238U,232Th, and40K in collected sedimentary rock samples in different places of Turkey. The measurements have been performed usingγ-ray spectrometer containing NaI(Tl) detector and multichannel analyser (MCA). Absorbed dose rate (D), annual effective dose (AED), radium equivalent activities (Raeq), external hazard index (Hex), and internal hazard index (Hin) associated with the natural radionuclide were calculated to assess the radiation hazard of the natural radioactivity in the sedimentary rock samples. The average values of absorbed dose rate in air (D), annual effective dose (AED), radium equivalent activity (Raeq), external hazard index (Hex), and internal hazard index (Hin) were calculated and these were 45.425 nGy/h, 0.056 mSv/y, 99.014 Bq/kg, 0.267, and 0.361, respectively.

Cathodoluminescence of alkali feldspars and radiation effects on the luminescent properties

Cathodoluminescence (CL) spectroscopy provides useful information about the existence of radiation-induced defect centers with a few micrometer resolutions and therefore has great potential to estimate the accumulated dose of natural radiation in micrometer-ordered mineral grains from radioactive decay. Although great scientific interest exists concerning the CL of various types of minerals, very few investigation have been conducted on the luminescence properties of radiation-induced alkali feldspars. This study, therefore, has sought a clarification of radiation effects on emission centers detected by CL analysis of alkali feldspar implanted with He+ ions at 4.0 MeV, which corresponds to the energy of an α particle derived from radioactive decay of 238U and 232Th. Panchromatic CL images of cross sections of sanidine, orthoclase, and microcline show a dark line with ~1 μm width on the bright luminescent background at 12–15 μm beneath the implanted surface, of which behavior may be corresponding to the electronic energy loss process of 4.0 MeV He+ ion. CL and Raman spectroscopy revealed that He+ ion implantation may leads to a partial destruction of the feldspar framework and Na+ migration, resulting in a quenching of CL emission from alkali feldspar, proportional to the radiation dose. CL spectra of unimplanted and He+-ion-implanted sanidine, orthoclase and microcline have emission bands at ~400–410 nm and at ~730 nm. Deconvolution of the CL spectra can successfully separate these emission bands into emission components at 3.05, 2.81, 2.09, 1.73, and 1.68 eV. These components are assigned to the Ti4+ impurity, Al-O−-Al/Ti defect, a radiation-induced defect center, and Fe3+ impurities on the T1 and T2 sites, respectively. The intensity at 3.05 eV negatively correlates with radiation dose owing to decreases in the luminescence efficiency. A slight Na+ diffusion and breaking of the linkage between Ti4+ and oxygen as a ligand might reduce the activation energy, which decreases the availability of radiative energy in the luminescence process of Ti4+ impurity centers. Furthermore, He+ ion implantation causes electron holes to be trapped at and released from Lowenstein bridges as a consequence of Na+ migration and leads to a partial destruction of Al-O bonds, which might be responsible for an increase and decrease in the intensity of emission component at 2.81 eV. With an enhanced radiation dose, there is a decrease in intensity at 1.73 eV and an increase in intensity at 1.68 eV. Deconvoluted CL spectra of the alkali feldspars reveal a positive correlation between intensity at 2.09 eV and the radiation dose, which may be due to the formation of a radiation-induced defect center. These correlations can be fitted by an exponential curve, where the gradients differ between the alkali feldspars studied, and are largest for the microcline, followed by the orthoclase and then the sanidine. The intensity at 2.09 eV has the potential to be used in geodosimetry and geochronometry.

Natural radiation doses due to radioactivity in northern part of Jordan

The aim of this study is to present an assessment of radiation doses received by the public in selected areas of northern part of Jordan, due to Background Radiation. This region included a 330 km length area, in five governorates in northern Jordan: Irbid, Mafraq, Zarqa, Jarash, and Ajloun. Using a portable Geiger–Muller counter, and NaI(Tl) detector, the area has been surveyed. The measured absorbed dose rates in air were in the range of 10 –250 nSv/h. Further studies should be implemented to determine the concentrations of natural radioactive materials.