Search Results (7)

This study analyzes the concentration of radioactive material in the soil near the Maanshan nuclear power plant (NPP). Out of the thirty samples, only one sample was found to have ¹³⁷Cs radioactivity measuring 2.58 Bq/kg. The activity concentrations were 77.2–517.7 Bq/kg, 3.9–31.6 Bq/Kg, and 5.3–39.1 Bq/kg, respectively, with mean values of 344.4 Bq/kg, 18.6 Bq/kg, and 26.5 Bq/kg for ⁴⁰K, ²²⁶Ra, and ²³²Th, respectively. These levels are lower than the global average of soil activity concentrations. The activity concentrations varied, with the highest levels being 7–8 times greater than the lowest levels. Clay content had a positive correlation and sand content had a negative correlation with ⁴⁰K, ²²⁶Ra, and ²³²Th activity concentrations. The activity concentrations followed a normal distribution for ⁴⁰K, ²²⁶Ra, and ²³²Th. The activity ratios for ²³²Th/²²⁶Ra, ⁴⁰K/²³²Th, and ⁴⁰K/²²⁶Ra were 1.43 ± 0.22, 13.1 ± 1.9, and 18.8 ± 4.1, respectively, and ratios show light minerals in the soils. The average values for external hazard indices (H_ex) and radium equivalent activity (Ra_eq) were 0.22 Bq/kg and 83.0 Bq/kg, respectively, both of which are below the recommended limit values of 1.0 Bq/kg and 370 Bq/kg, respectively. The outdoor absorbed dose rate (D_Rex) and annual effective dose equivalent (AED_ex) were 39.0 nGy/h and 47.8 μSv/y, respectively, both of which are lower than the global soil average of 59 nGy/h and 70 μSv/y, respectively. These results indicate that local residents and tourists are not at significant risk of radiological hazards from the soil. The soil activity concentrations can serve as a baseline for continuous monitoring, even after the Maanshan NPP is decommissioned in 2025. Full article

Several dose distribution maps were obtained using a gamma radiation detector mounted to a drone. Based on the results and experience of the experiments, the shortcomings of the system and the possibilities for further development were identified. The primary goal of the development was to create a more compact, easy-to-carry, and easy-to-install system with increased sensitivity, which was achieved by several different methods and their combinations. During the discrete measurement procedure, the aim was to decrease the detection threshold, +0.005 to +0.007 μS/h measured above the background radiation. The increase in sensitivity was based on the characteristic energy spectrum of radiative materials. We took advantage of the fact that the radiating samples do not evenly increase the amount of gamma radiation over the entire energy spectrum. During the processing of the measurement data, we performed a comparison with the background radiation in the vicinity of the energy peaks characteristic of the sample and its decay products. This provides a better signal-to-noise ratio, thus enabling a more sensitive detection procedure. An important feature of our method is that in the traditional intensity curve displayed as a function of flight time only noise is visible, therefore one cannot directly conclude the presence of the sample. However, our method is clearly able to identify the location of the searched source at a height of 8 m with a continuous flight speed of 2 m/s using a 500 μS/h activity sample (as measured at a distance of 0.1 m from the sample). The increase in sensitivity allows either a higher scanning height (approximately +1 to 2 m) or, in the case of the same aircraft at the same altitude, a larger area from one take-off. Of course, the scan height or scan speed can increase significantly if the activity of the source being sought is high. In our experiments, we used a natural uranium mineral (Autunite) with activity far below that of artificially produced isotopes. In the series of our experiments, we also covered the detection of several sources, which modeled the possibility of mapping scattered active sources. The main advantages of the system developed and presented by us over the survey procedures used in practice is that a large area can be mobilized easily, without the risk of a human operator in the field, and the survey of a large area can be carried out at a low cost. The purpose of the system is to detect the presence of the source and to localize it to such an extent that the localization can then be easily refined by manual or other ground procedures. As we do not aim for positioning accuracy by centimeter, standard GPS localization is sufficient for the measurements. During the measurements, the geographical coordinates are interpreted in the GWS’84 system. The coordinates of the latitude and longitude circles are also shown in this system in the figures presented. Full article

In urban areas, forest patches and parks are usually the places where people spend most of their time outdoors. Because of poor environmental protection policy and insufficient investment in industry and energy, Serbia is often ranked among the European countries with the greatest environmental pollution. In recent years, ecological protests have been organized throughout the country with the aim of raising ecological awareness and resolving environmental issues. The topic has become particularly popular since the plans for opening new mining areas in western Serbia came to the fore. This study was conducted with the aim to investigate radioactivity levels and metals content in soil and foliage of the most popular parks in Belgrade, the capital and largest city of Serbia. Based on a GIS (geographic information system) approach, the spatial distribution maps of radionuclides (²²⁶Ra, ²³²Th, ⁴⁰K, ⁷Be, and ¹³⁷Cs) and metals (As, Cd, Cr, Co, Cu, Na, Ni, Pb, Zn, K, Ca, Mg, and Mn) were made. Ambient dose-equivalent rate in air was also measured. The annual effective doses and excess lifetime cancer risk from radionuclides were calculated. Health effects of exposure to heavy metals in soil were estimated by noncarcinogenic and carcinogenic risk assessment. Full article

A gamma spectrometric analysis of rock samples collected from the Precambrian Oban Massif, southeastern Nigeria, was performed to determine some primordial radioelements’ activity concentrations: U-238, Th-232, and K-40, and their associated radiological hazards. The mean activity of the primordial radionuclides was determined to be 1073.06 ± 0.65, 160.74 ± 1.32, and 250.76 ± 0.91 Bq·kg⁻¹ for ⁴⁰K, ²³⁸U, and ²³²Th, respectively, showing that they are inhomogeneously distributed, with activity changing with the rock type and location. The activity concentrations are highest in biotite garnet schist, quartz diorite, and biotite gneiss rock domains. The mean values of the radiological hazards are 0.08 Bq·kg⁻¹ (alpha index), 2.15 Bq·kg⁻¹(gamma index), 2.06 Bq·kg⁻¹(internal) and 1.63 Bq·kg⁻¹ (external4.30 Bq·kg⁻¹(representative level index6), 602.23 Bq·kg⁻¹, (radium equivalent), 780 nGy·h⁻¹ (total absorbed dose rate), 270.91 nGy·h⁻¹ (indoor), 509.78 nGy·h⁻¹ (outdoor), 624.99, 1329.07 and 1954.06 mSv·yr⁻¹ (outdoor, indoor and total annual effective dose equivalent, respectively), 6448.40 (cumulative excess lifetime cancer risk) and 248.94–3761.47 Bq·kg⁻¹ (annual gonadal dose equivalent). These results are higher than their various permissible limits (except at Ako Community) and suggest that rocks in the area may be unsuitable for constructing dwelling places. It is strongly advised that basic safety standards and precautionary measures recommended by the European Commission should be strictly adhered to while dealing with these rocks. Full article

This study was developed to carry out a comprehensive radiological assessment of natural radioactivity for river sediment samples from Calabria, southern Italy, and to define a baseline background for the area on a radiation map. In the studied area, elevated levels of natural radionuclides are expected, due to the outcropping acidic intrusive and metamorphic rocks from which the radioactive elements derive. To identify and quantify the natural radioisotopes, ninety river sediment samples from nine selected coastal sampling points (ten samples for each point) were collected as representative of the Ionian and the Tyrrhenian coastline of Calabria. The samples were analyzed using a gamma ray spectrometer equipped with a high-purity germanium (HPGe) detector. The values of mean activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K measured for the studied samples are (21.3 ± 6.3) Bq kg⁻¹, (30.3 ± 4.5) Bq kg⁻¹ and (849 ± 79) Bq kg⁻¹, respectively. The calculated radiological hazard indices showed average values of 63 nGy h⁻¹ (absorbed dose rate), 0.078 mSv y⁻¹ (effective dose outdoors), 0.111 mSv y⁻¹ (effective dose indoors), 63 Bq kg⁻¹ (radium equivalent), 0.35 (H_ex), 0.41 (H_in), 0.50 (activity concentration index) and 458 µSv y⁻¹ (Annual Gonadal Equivalent Dose, AGED). In order to delineate the spatial distribution of natural radionuclides on the radiological map and to identify the areas with low, medium and high radioactivity values, the Surfer 10 software was employed. Finally, the multivariate statistical analysis was performed to deduce the interdependency and any existing relationships between the radiological indices and the concentrations of the radionuclides. The results of this study, also compared with values of other locations of the Italian Peninsula characterized by similar local geological conditions, can be used as a baseline for future investigations about radioactivity background in the investigated area. Full article

The amount of outdoor particles that indoor environments receive depends on the particle infiltration factors (F_in), peculiar of each environment, and on the outdoor aerosol concentrations and size distributions. The respiratory doses received, while residing indoor, will change accordingly. This study aims to ascertain to what extent such doses are affected by the vertical distance from the traffic sources. Particle number size distributions have been simultaneously measured at street level and at about 20 m height in a street canyon in downtown Rome. The same F_in have been adopted to estimate indoor aerosol concentrations, due to the infiltration of outdoor particles and then the relevant daily respiratory doses. Aerosol concentrations at ground floor were more than double than at 20 m height and richer in ultrafine particles. Thus, although aerosol infiltration efficiency was on average higher at 20 m height than at ground floor, particles more abundantly infiltrated at ground level. On a daily basis, this involved a 2.5-fold higher dose at ground level than at 20 m height. At both levels, such doses were greater than those estimated over the period of activity of some indoor aerosol sources; therefore, they represent an important contribution to the total daily dose. Full article

Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h⁻¹. At the same sites, 48 soil samples were taken to obtain the activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h⁻¹. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg⁻¹, for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. From the analysis, the spatial distribution of ²³²Th, ²²⁶Ra and ⁴⁰K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize. Full article