A Gaussian-plume based Monte Carlo method for calculating radiation dose in the near field of buildings.

A Monte Carlo (MC) programme was written using the dose point kernel method to calculate doses in the roof zone of a building from nearby releases of radioactive gases. A Gaussian Plume Model (GPM) was parameterised to account for near-field building effects on plume spread and reflection from the roof. Rooftop recirculation zones and building-generated plume spread effects were accounted in a novel Dual Gaussian Plume (DGP) formulation used with the MC model, which allowed for the selection of angle of approach flow, plume release height in relation to the building and position of the release point in relation to the leading edge of the building. Three-dimensional wind tunnel concentration field data were used for the parameterisation. The MC code used the parameterised concentration field to calculate the contributions to effective dose from inhalation, cloud immersion from positron/beta particles, and gamma-ray dose for a wide range of receptor dose positions in the roof zone, including receptor positions at different heights above the roof. Broad trends in predicted radiation dose with angle of approach flow, release position in relation to the building and release height are shown. Alternative approaches for the derivation of the concentration field are discussed.

Assessment of natural radioactivity in the RCC building materials used in the valley region of Manipur, India.

An assessment of radioactivity concentration of reinforced cement concrete types of house was conducted in the valley region of Manipur, India. The average radioactivity concentration of 226Ra, 232Th, and 40K of portland cements are 39 (range: 32-52) Bqkg-1, 36 (range: 22-62) Bqkg-1, and 1812 (1254-2424) Bqkg-1; for concrete are 36 (range: 26-45) Bqkg-1, 65 (range: 45-86) Bqkg-1, and 660 (639-681) Bqkg-1; for sand are 45 (30-61) Bqkg-1, 114 (range: 55-212) Bqkg-1, and 1859 (range: 1413-2232) Bqkg-1; and for bricks are 30 (range: 24-37) Bqkg-1, 148 (range:79-184) Bqkg-1, and 1444 (range: 1093-2103) Bqkg-1, respectively. The annual effective dose was observed with an average value of 1.9 (range: 0.9-3.3) mSvy-1. However, gamma index was observed with an average value of 1.1 (range: 0.5-2.0).

Assessment of natural and artificial radioactivity concentrations in infant powdered milk consumed in Albania and estimation of the annual effective dose.

This study evaluates the radiological risk associated with the consumption of infant powdered milk in Albania. Infant powdered milk is the basic foodstuff for their growth and development in many countries around the world. The activity concentration of radionuclides (40K, 226Ra, 232Th and 137Cs) was measured in fourteen types by using the gamma-ray technique. The results indicated that the activity concentration of 40K, 226Ra and 232Th were detected in all selected samples, whereas 137Cs were not detected in most of them. The activity concentration of 40K, 226Ra and 232Th varies from 92.83 ± 4.32 to 400.53 ± 17.00 Bq kg-1, 0.80 ± 0.15 to 4.91 ± 0.28 Bq kg-1 and 0.19 ± 0.02 to 1.89 ± 0.14 Bq kg-1, respectively. The highest value for 137Cs was found to be 0.36 ± 0.03 Bq kg-1. The average values of Annual Effective Dose (AED) due to consumption of powdered milk were found to be 664.54 ± 31.11 µSv y-1 for infants ≤1 year and 138.53 ± 5.40 µSv y-1 for infants 1-2 years. The values of dose in this study were lower than the recommended limit of 1 mSv y-1 set by WHO/FAO and ICRP for all ages. Therefore, brands of powdered milk are safe, so, these can be normally consumed by infants in Albania.

137Cesium (137Cs) assessment in wild boars from northwestern Italy.

Radionuclide contamination is a serious health issue caused by nuclear experiments and plant accidents, as seen for the Chernobyl and Fukushima nuclear plants. Italy has been especially interested in northwestern alpine regions, as have several other nations. The aim of this work was to indagate 134Cs and 137Cs contamination in wild boars, which were considered bioindicators sampled in the Chisone/Germanasca Valley and the Pellice Valley districts (Piedmont, Italy) in two hunting seasons (2014 and 2016). In the 2014 season, only the livers of the animals (n = 48) were sampled, whereas in 2016, five different anatomical sampling sites were sampled for each animal (n = 16). The analyses were conducted in an accredited laboratory (Agenzia Regionale per la Protezione dell'Ambiente-ARPA) by the aid of an HPGe detector (Ortec) with a relative efficiency of 50%. In general, the contamination levels registered in 2014 were under the detection limit for 134Cs and low for 137Cs (Chisone/Germanasca valley: min: 0.0, max: 23.9 median 11.0 Bq/kg vs Pellice valley: min 0, max: 31.7, median: 9.6 Bq/kg) and no health concern can be supposed. In the first-year samples, the liver showed a negative correlation between age and contamination level. In the second year of sampling, low levels were confirmed (min: 3.1 Bq/kg, max: 113.3; median 17.7 Bq/kg). Multiple sampling from the same animal showed that the diaphragm (median = 27.7 Bq/kg) kidney (27.4) and tongue (27.6) were more contaminated than the liver (17.7) and spleen (15.3). Moreover, a linear mixed model revealed a negative organ-by-age interaction, meaning that interorgan differences in contamination level were greater in younger (5-11 months) than in older (18-36 months) animals. Different feeding habits can be the explanation. Our paper shows that muscle sites (diaphragm and tongue) can be useful for radionuclide pollution surveillance in wild boar populations and that younger animals show more interorgan variability in contamination levels than older animals. More investigations are needed to confirm this correlation and to fulfill the request for more data to achieve better risk assessment.

Radon Exposure Assessment in Occupational and Environmental Settings: An Overview of Instruments and Methods.

Radon is a naturally occurring noble radioactive gas that poses significant health risks, particularly lung cancer, due to its colorless, odorless, and tasteless nature, which makes detection challenging without formal testing. It is found in soil, rock, and water, and it infiltrates indoor environments, necessitating regulatory standards and guidelines from organizations such as the Environmental Protection Agency, the World Health Organization, and the Occupational Health and Safety Agency to mitigate exposure. In this paper, we present various methods and instruments for radon assessment in occupational and environmental settings. Discussion on long- and short-term monitoring, including grab sampling, radon dosimetry, and continuous real-time monitoring, is provided. The comparative analysis of detection techniques-active versus passive-is highlighted from real-time data and long-term exposure assessment, including advances in sensor technology, data processing, and public awareness, to improve radon exposure evaluation techniques.

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

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

Monte Carlo simulation for photon energy response from the RADOS dosemeter.

Ionizing radiation interaction models are commonly included in Monte Carlo codes. However, as there are different models and different output quantities available, it is important to understand the physical phenomena used. So, the aim of this study is to analyze the photon interaction model called Simple Physical Treatment of the Monte Carlo code MCNPX to estimate the energy dependence of photons from the RADOS dosemeter and to validate this calculation method by comparing it with experimental results found in the literature. The energy deposition in the MTS-N detector and the air kerma were obtained accompanied by their uncertainties, which varied between 1.5% and 3.0%. The RADOS dosemeter simulation and the calculation methodology applied in this study have been validated. Therefore, when using the Simple Physical Treatment model, the effective dose can be corrected by a correction factor calculated from the simulated results.

Rapid assessment of cosmic radiation exposure in aviation based on BP neural network method.

Cosmic radiation exposure is one of the important health concerns for aircrews. In this work, we constructed a back propagation neural network model for the real-time and rapid assessment of cosmic radiation exposure to the public in aviation. The multi-dimensional dataset for this neural network was created from modeling the process of cosmic ray transportation in magnetic field by geomagnetic cutoff rigidity method and air shower simulation by a Monte Carlo based Geant4 code. The dataset was characterized by parameters including cosmic ray energy spectrum, Kp-index, coordinated universal time, altitude, latitude, and longitude. The effective dose and dose rate was finally converted from the particle fluxes at flight position by the neural network. This work shows a good agreement with other models from International Civil Aviation Organization. It is also illustrated that the effective dose rate by galactic cosmic ray is <10 µSv h-1 and the value during ground level enhancement (GLE) 42 is 4 ~ 10 times larger on the routes calculated in this work. In GLE 69, the effective dose rate reaches several mSv h-1 in the polar region. Based on this model, a real-time warning system is achieved.

Commissioning of the first hospital-based PET radiopharmaceutical cyclotron in Greece: personnel dose assessment.

The role of18F-fluoro-deoxy-glucose in positron emission tomography (PET) imaging is well established in diagnosis and management of cancer patients. Installations of on-site self-shielded mini cyclotrons are increasing. The Dose on Demand Biomarker Generator BG-75 was installed at Metaxa Cancer Hospital, Greece, in May 2021 and is the first hospital-based PET radiopharmaceutical cyclotron in the country. Personnel expected external exposure was established during commissioning; internal exposure is not expected. Personnel dose was estimated with two methods: survey meter measurements in various locations combined with the time spent in each location, and direct measurement using electronic personal dosemeters. Gamma and neutron radiation readings outside the cyclotron vault were at background levels. Inside the cyclotron vault, the highest recorded radiation readings by the target were 18µSv h-1for both gammas and neutrons with cyclotron in operational mode; at one meter, the values were 5µSv h-1and 4µSv h-1, respectively. The annual expected whole body dose per cyclotron operator is 0.6 mSv, and the respective extremity dose 16 mSv. The annual expected whole body and extremity dose for the radiochemist is 0.3 mSv and 25 mSv, respectively. The respective annual dose estimates for the medical physicists are < 1 mSv. The expected personnel doses are well below the regulatory limits and local as low as reasonably achievable (ALARA) levels. With experience and a robust ALARA program, personnel exposure could be further reduced.

Medical staff monitoring in interventional cardiology: over apron dosemeter placement based on measurements and simulations.

Interventional cardiology is characterized by high radiation exposure for both the patient and the operator. Adequate shielding and monitoring of the operator are fundamental to comply with radiation protection principles. In a previous work, the effect on the dose of the dosemeter position on the chest was studied. In this paper, the investigation has been completed, employing an anthropomorphic thorax phantom, equipped with arms. Although there are differences between the Monte Carlo simulations and the measurements, similar trends are observed, showing that the reduction in dose, due to the arms, is between 20 and 60%, compared with the situation without arms. For that reason, considering a dosemeter placed on the chest, the upper position, which is the least affected by the arms, should be preferred while the extreme lateral position, near the armpit, should be avoided.

The Radium triplet 226Ra, 228Ra, 224Ra in saline deep water - a valuable information source.

The occurrence of enhanced concentration of the radium triplet 226Ra, 228Ra and 224Ra is a frequently observed property of highly saline anoxic deep water as used e.g. in geothermal plants. In the present study we develop a model to explain the observed activity levels in the brines. The model considers processes at the rock-fluid interface of the aquifer like alpha recoil, sorption and surface precipitation and is implemented by means of a Monte Carlo simulation. The outcomes of the simulations indicate the dominating role of fine-grained constituents of the reservoir rock, e.g. claystone with enhanced specific activities of the natural decay chains. Mass fractions of such material in the order of a few percent are sufficient to result in radium fluid concentrations >1 Bq l-1. Also a generally valid relation between the Th/U ratio in the aquifer rock and the 228Ra/226Ra activity ratio in the fluid was found. This link improves the agreement between radium fluid data and the mean Th/U ratio of the Earth's crust. The 224Ra/228Ra fluid ratios reflect the transport time from the location of last radium release to the sampling point. The model findings were applied to a well investigated aquifer used in a geothermal plant in the North German Basin. An eight component system of the aquifer rock was established as the basis for the simulation of the radium concentrations in the deep fluid. The comparison between simulation and fluid analyses revealed a degree of radium sorption of about 50 %, which is necessary to match the model's results with the measurements. On the other hand, the 228Ra/226Ra fluid ratio of the brine was well reproduced by the simulation, showing the suitability of the model even in complex heterogeneous reservoirs. From the 224Ra/228Ra fluid ratios a transition from pore-to fracture-guided transport < 10 m distance from the production well is suggested. Precipitates from such deep fluids occurring after changes of the thermodynamic conditions are able to accumulate radium isotopes in Ba/Sr-sulphate phases. The time dependence of the radioactive disequilibrium between 226Ra, 228Ra and its child 228Th in such scales is described by a mathematical model and is applied to two different uptake models. Based on this approach, age determinations on precipitates found in different components of a geothermal plant are conducted. They reveal the triggering of scale formation due to modifications in the plant. The results are suitable for drawing conclusions about the operation of the system, which result in a reduction in the amount of scale and a reduction in downtimes.

Neighborhood-level socioeconomic disparities in Radon testing in North Carolina from 2010 to 2020.

Radon is a naturally occurring radioactive gas that poses significant health risks to humans, including increased risk of lung cancer. This study investigates the association of neighborhood-level socioeconomic variables with radon testing and radon exposure levels in North Carolina between 2010 and 2020. Our analysis of the two largest commercial household radon tests reveals that 67% of census tracts had testing rates below 10 tests per 1000 population, indicating low testing prevalence. Low radon levels (<2 pCi/L) were detected in 74.1% of the tracts (n = 1626), while medium levels of 2-4 pCi/L and ≥4 pCi/L were observed in 17.2% (n = 378) and 1.6% (n = 36) of the tracts. A generalized spatial regression model was employed to analyze the association between neighborhood-level socioeconomic variables and radon testing rates (per 1000 households), controlling for median radon testing results. The results show a positive correlation (P-value <0.001) of testing rate with various indicators of neighborhood affluence including education level, income, and occupation. In contrast, neighborhood disadvantage, including poverty, unemployment, and public assistance, was associated with a lower radon-testing rate (P-value <0.001). These findings highlight the need for targeted interventions to address socioeconomic disparities in radon testing and promote awareness and access to testing resources in lower socio-economic neighborhoods. Improving testing rates can effectively address radon-related health risks in North Carolina and across the U.S.

Relevance of radon progeny measurements for the assessment of inhalation doses in groundwater utilities.

The high radon concentrations measured in the indoor air of groundwater facilities and the prevalence of the problem have been known for several years. Unlike in other workplaces, in groundwater plants, radon is released into the air from the water treatment processes. During the measurements of this study, the average radon concentrations varied from 500 to 8800 Bq m-3. In addition, the indoor air of the treatment plants is filtered and there are no significant internal aerosol sources. However, only a few published studies on groundwater plants have investigated the properties of the radon progeny aerosol, such as the equilibrium factor (F) or the size distribution of the aerosol, which are important for assessing the dose received by workers. Moreover, the International Commission on Radiological Protection has not provided generic aerosol parameter values for dose assessment in groundwater treatment facilities. In this study, radon and radon progeny measurements were carried out at three groundwater plants. The results indicate surprisingly high unattached fractions (fp= 0.27-0.58), suggesting a low aerosol concentration in indoor air. The correspondingFvalues were 0.09-0.42, well below those measured in previous studies. Based on a comparison of the effective dose rate calculations, either the determination of thefpor, with certain limitations, the measurement of radon is recommended. Dose rate calculation based on the potential alpha energy concentration alone proved unreliable.

Cosmic-ray exposure assessment using particle and heavy ion transport code system: case study Douala-Cameroon.

According to UNSCEAR, cosmic radiation contributes to ~16% (0.39 mSv/y) of the total dose received by the public at sea level. The exposure to cosmic rays at a specific location is therefore a non-negligible parameter that contributes to the assessment of the overall public exposure to radiation. In this study, simulations were conducted with the Particle and Heavy Ion Transport code System, a Monte Carlo code, to determine the fluxes and effective dose due to cosmic rays received by the population of Douala. In minimum solar activity, the total effective dose considering the contribution of neutron, muon+, muon-, electron, positron and photon, was found to be 0.31 ± 0.02 mSv/y at the ground level. For maximum solar activity, it was found to be 0.27 ± 0.02 mSv/y at ground level. During maximum solar activity, galactic cosmic rays are reduced by solar flares and winds, resulting in an increase in the solar cosmic-ray component and a decrease in the galactic cosmic-ray component on Earth. This ultimately leads to a decrease in the total cosmic radiation on Earth. These results were found to be smaller than the UNSCEAR values, thus suggesting a good estimation for the population of Douala city located near the equatorial line. In fact, the cosmic radiation is more deflected at the equator than near the pole. Muons+ were found to be the main contributors to human exposure to cosmic radiation at ground level, with ~38% of the total effective dose due to cosmic exposure. However, electrons and positrons were found to be the less contributors to cosmic radiation exposure. As regards the obtained results, the population of Douala is not significantly exposed to cosmic radiation.

Potential risk assessment: a model for quality evaluation in fluoroscopy-guided interventional procedures.

This study presented a model applied for potential risk assessment in an interventional radiology setting. The model of potential risk assessment (MARP) consisted of the creation of a scale of indicators ranging from 0 to 5. The radiation levels were categorized according to gender, kind of procedure, value of kerma air product (Pka), and accumulated radiation dose (mGy). The MARP model was applied in 121 institutions over 8 y. A total of 201 656 patient radiation doses (Dose-area product and accumulated kerma) data were launched into the system over time, with an average of 22 406 doses per year. In the context of the workers (cardiologists, radiographers, and nurses) monitored during the MARP application, 8007 cases (with an average of 890 per year) of occupational radiation doses were recorded. This study showed a strategy for quality evaluation in fluoroscopy using a model with a compulsory information system for monitoring safety.

Natural radionuclides and radiological risk assessment in the stream and river sediments of a high background natural radiation area Kanyakumari, India.

The Kanyakumari coast is known to be a high background natural radiation area due to the placer deposits of heavy minerals such as ilmenite, monazite, and rutile. The Kanyakumari river sediments that could be the source of the elevated amounts of natural radionuclides in the coastal sands have been studied in this paper. The activity concentrations of primordial radionuclides 226Ra, 232Th, and 40K were determined using high-purity germanium (HPGe) gamma-ray spectrometry. The mean activity concentrations of 226Ra, 232Th, and 40K were found to be 75 Bq kg-1, 565 Bq kg-1, and 360 Bq kg-1, respectively. The mean absorbed dose rate was 395 nGy h-1. Radiological hazard parameters were studied and compared with the world average values. The contribution of 232Th to the total dose rate was found to be higher than that of the two other radionuclides. The high mean ratio of 232Th/226Ra suggested an enrichment of 232Th and the occurrence of 226Ra leaching due to an oxidizing environment. Principal component analysis (PCA) was carried out for the radionuclides in order to discriminate the source of the sediments. This study provides new insights into the distribution of natural radionuclides in sediments of rivers and streams.

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.

A fast correction method of the scattering contributions in the area gamma dosemeter calibration field.

In the calibration procedure of area gamma dosemeters, how to accurately evaluate and correct the scattering contribution from the complex environmental factors to the point of test is the key problem to ensure the calibration accuracy. This paper proposed a fast correction method of the scattering contributions in the area gamma dosemeter calibration field. First, Monte Carlo method is employed to simulate the influence of scattering caused by different environmental factors in the calibration field, which is named as semi-panoramic reference radiation field. Then, a prediction model of the relationship between environmental factors and environmental scattering contribution is constructed based on the simulation data through the least squares support vector machine. With the model, the scattering contribution from the environmental factors can be fast estimated to correct the calibration results of the area gamma dosemeters, which will improve the accuracy of the calibration.

Assessment of environmental radiological impact in former metallic mines in Extremadura (Spain): A case study.

Metal mining in the Extremadura region was very important in the 19th and 20th centuries. However, due to different reasons the great majority of mines ceased operations, leading to plenty of abandoned mining sites, most of them with on-site waste dumps. Although metal extraction is not radioactive per se, it is considered a NORM activity. In this study, three former mining sites, in which Pb-V-Zn-Ag, Pb-Ag, and Pb-Zn were extracted, were selected to assess the radiological impact on the population and the environment. The external γ exposure was estimated by determining the effective dose and elaborating isodose maps of the sites. The presence of the mining sites increased up to 0.41 mSv/y the effective dose over the surrounding background, which is below the reference value of 1 mSv/y. In only one mining site, the uranium and radium activity concentration of waste dumps were higher than the surrounding soil. The soil to plant (wild grass) transfer factors were similar to other reported values without the influence of NORM activities. So, no enhanced transfer of radionuclides was observed. The radiological impact on the environment was assessed by the risk to non-human biota using the tiered approach developed in ERICA Tool. The sum of the risk quotients of all considered radionuclides in the most conservative Tier 1 was below 1. Total dose rates for several terrestrial Reference Animal and Plants (RAPs) were estimated using Tier 3, obtaining values below 40 µGy/h. Therefore, the impact on non-human biota can be considered as negligible.

The presence of radiotoxic 210Po and 210Pb in Ukrainian wild medicinal plants and the assessment of related dose and cancer risk.

Herbal plants are considered natural pharmaceuticals but also accumulate chemical elements and compounds at high levels. 210Po and 210Pb are highly radiotoxic and may cause carcinogenesis due to ionizing radiation. Thirteen of the most popular wild-growing herbaceous plant species, mostly included in the European Pharmacopoeia, were collected across Ukraine. 210Po and 210Pb were determined in the medicinal plants, and their radiotoxicity and cancer risk were calculated. The results of 210Po activities measured in herbal raw material ranged from 2.28 Bq kg-1 dw (where dw is dry weight) in herb of common horsetail (Equisetum arvense L.) collected near Lviv to 37.7 Bq kg-1 dw in leaves of common birch (Betula pendula Roth.) from Rava Ruska. The activity concentrations of 210Pb varied from 0.44 Bq kg-1 dw in leaves of common birch from Starokostyantyniv to 28.4 Bq kg-1 dw in leaves of common birch from Mizhhirya. There were statistically significant differences between 210Po and 210Pb content in flowers, leaves, and aerial portions. The studies indicated that the estimated annual effective radiation dose from Ukrainian herbs consumption was low, ranging 5.00-82.6 µSv from 210Po and 0.56-35.8 µSv from 210Pb, while the cancer morbidity and mortality risk ranged from 10-4 to 10-6. The presented data indicated no radiological risk related to using herbal plant materials.