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The fast prediction of the extent and impact of accidental air pollution releases is important to enable a quick and informed response, especially in cities. Despite this importance, only a small number of case studies are available studying the dispersion of air pollutants from fires in a short distance (O(1 km)) in urban areas. While monitoring pollution levels in Southampton, UK, using low-cost sensors, a fire broke out from an outbuilding containing roughly 3000 reels of highly flammable cine nitrate film and movie equipment, which resulted in high values of PM2.5 being measured by the sensors approximately 1500 m downstream of the fire site. This provided a unique opportunity to evaluate urban air pollution dispersion models using observed data for PM2.5 and the meteorological conditions. Two numerical approaches were used to simulate the plume from the transient fire: a high-fidelity computational fluid dynamics model with large-eddy simulation (LES) embedded in the open-source package OpenFOAM, and a lower-fidelity Gaussian plume model implemented in a commercial software package: the Atmospheric Dispersion Modeling System (ADMS). Both numerical models were able to quantitatively reproduce consistent spatial and temporal profiles of the PM2.5 concentration at approximately 1500 m downstream of the fire site. Considering the unavoidable large uncertainties, a comparison between the sensor measurements and the numerical predictions was carried out, leading to an approximate estimation of the emission rate, temperature, and the start and duration of the fire. The estimation of the fire start time was consistent with the local authority report. The LES data showed that the fire lasted for at least 80 min at an emission rate of 50 g/s of PM2.5. The emission was significantly greater than a 'normal' house fire reported in the literature, suggesting the crucial importance of the emission estimation and monitoring of PM2.5 concentration in such incidents. Finally, we discuss the advantages and limitations of the two numerical approaches, aiming to suggest the selection of fast-response numerical models at various compromised levels of accuracy, efficiency and cost. [ABSTRACT FROM AUTHOR]

Many regulatory requirements add significant delay in the licensing of new nuclear power stations. One area of particular interest is the environmental impact of potential atmospheric release. The purpose of this research is to demonstrate effectiveness of meteorological data mining and synthesis from offsite locations to reduce need for onsite data, hence allowing rapid licensing. The automated procedures tested for data mining and extraction of meteorological data from multiple offsite sources and the data analytic tool developed for data fusion are presented here. Three important meteorological parameters from regulatory compliance are considered for this analysis: wind velocity, wind direction, and atmospheric stability. Callaway Nuclear Power Plant (CNPP) is used as our reference site. CNPP uses the Δ T Δ z approach while we use the Vogt method to estimated stability for the offsite locations. Stability classification correlation coefficients between the reference plant and Columbia Regional Airport range from −0.087 to 0.826 for raw with an average of 0.317 ± 0.313. With travel time, correction changed slightly, i.e., a 10 m observation 0.064 ± 0.249 and 0.028 ± 0.123 and a 60 m observation 0.103 ± 0.265 and 0.063 ± 0.155 for the wind from the reference plant to the airport and vice versa, respectively. For Jefferson City Memorial Airport, raw data correlation was from −0.083 to 0.771, with an average of 0.358 ± 0.321. With travel time, correction changed slightly, i.e., 10 m observation 0.075 ± 0.208 and −0.073 ± 0.255 and 60 m observation 0.018 ± 0.223 and −0.032 ± 0.248 for wind from the reference plant to the airport and vice versa, respectively. Stability classification correlation coefficients between the reference plant and St. Louis Lambert International Airport ranged from −0.083 to 0.763 for raw with an average of 0.314 ± 0.295. With travel time, correction changed slightly, i.e., 10 m observation −0.003 ± 0.307 and −0.030 ± 0.277 and 60 m observation −0.030 ± 0.193 and −0.005 ± 0.215 for wind from the reference plant to the airport and vice versa, respectively. It is important to observe that mathematically. stability class correlation coefficients were not great, but in most cases the predicted and observed values were only off by one stability class. Similar correlations were calculated for wind direction and velocities. Our result, when applied to a proposed nuclear power station, can significantly reduce time and effort to prepare a robust environmental protection plan required for license application. [ABSTRACT FROM AUTHOR]

Most Lagrangian dispersion models represent free tropospheric turbulence as a homogeneous steady‐state process. However, intermittent turbulent mixing in the free troposphere may be a significant source of mixing. We test a new parametrization scheme that represents spatial‐ and temporal‐varying turbulence in the free troposphere in the Met Office's Numerical Atmospheric‐dispersion Modelling Environment. We use semi‐idealized emissions of radon‐222 (222$$ {}^{222} $$Rn) from rocks and soil in the United Kingdom to evaluate the impact of using a variable free tropospheric turbulence parameterization on the dispersion of 222$$ {}^{222} $$Rn. We performed two experiments, the first using the existing steady‐state scheme and the second using the newly implemented spatio‐temporal‐varying scheme, for two case periods July 2018 and April 2021. We find that the turbulence in the varying scheme (represented by the vertical velocity variance) can range by two to three orders of magnitude (10 −4$$ {}^{-4} $$ to 10 −1$$ {}^{-1} $$ m 2$$ {}^2 $$·$$ \cdotp $$s −2$$ {}^{-2} $$) when compared with the steady‐state scheme (10 −2$$ {}^{-2} $$ m 2$$ {}^2 $$·$$ \cdotp $$s −2$$ {}^{-2} $$). In particular, low‐altitude turbulence is enhanced when synoptic conditions are conducive to forming low‐level jets. This leads to a greater dispersion in the free troposphere, reducing the mean monthly 222$$ {}^{222} $$Rn concentration above the boundary layer by 20–40% relative to the steady‐state scheme. We conclude that without a space–time‐varying free tropospheric turbulence scheme atmospheric dispersion may be significantly underestimated under synoptic conditions that are favourable for low‐level jet formation. This underestimation of dispersion may potentially result in inaccurate estimations of local emissions in top‐down greenhouse gas inventory studies. [ABSTRACT FROM AUTHOR]

Safety in nuclear energy utilization is crucial. In the event of a radioactive release incident, coupled with meteorological uncertainties, a radioactive plume can impact personnel evacuation. This paper presents an integrated solution for radionuclide release accident assessment and emergency evacuation decision making. The solution consists of three processes: atmospheric dispersion calculation, dose calculation, and path planning. The individual processes are connected through data exchange, thus allowing users to choose specific models based on experience. The proposed scheme combination is the Gaussian plume model, the dose conversion factor method, and an improved Dijkstra's path planning algorithm. This algorithm, combined with dispersion and dose results, weighs nodes using the moving expected dose, facilitating the path with minimum dose risk. A program for Atmospheric Diffusion and Dose Calculation (ADDC) is developed based on the recommended scheme. Advantages include ease of use, minimal data requirements, data accessibility, and efficient evacuation. Dose estimates and optimal evacuation routes can be obtained quickly and at very low cost in response to rapidly changing environmental conditions. In a case study at a Chinese planned nuclear plant, we consider a spent fuel pool water loss scenario, assessing dose risks from 2020 to 2022 meteorological statistics. In dose calculation, results reveal that during an SFP drying accident, the radiation dose in the core area (100 m away) can reach 30–150 mSv within 2 h, and at 500 m away, it can reach 5–15 mSv. The dose in all downwind directions can drop below 250 mSv within 60 m. In path planning, results reveal the program is capable of accurately and efficiently calculating the minimum dose evacuation route. The program's path reduces the effective dose by up to 67.3% compared to the shortest route, enhancino safety, and guiding post-accident decision making and planning. [ABSTRACT FROM AUTHOR]

AbstractEvaluating atmospheric dispersion and radiological doses in the vicinity of buildings is required for small modular reactors (SMRs) because of the reduced size of their exclusion area boundary. The current Canadian nuclear industry tool for these calculations implements the methodology defined in CSA Standard N288.2-M91, which was written to support large Canada Deuterium Uranium (CANDU) nuclear reactors as opposed to SMRs. The ORCA (On/offsite Radiological Consequences of Accidents) code has been developed to address this technical concern in addition to evaluating atmospheric dispersion and doses in the far field. The code calculates worker and public doses following an airborne release of radioactive material into the atmosphere under postulated accident conditions at a nuclear facility. The current paper presents the key assumptions and methods utilized in ORCA and discusses qualification of the software to the requirements of CSA Standard N286.7-16. The new model is applicable to SMRs and existing reactor designs and reduces conservatisms in the near field (i.e., <1 km from the source) relative to the methods in CSA N288.2-M91. [ABSTRACT FROM AUTHOR]

Safety and risk assessment of the offshore geological storage of carbon dioxide (CO 2) in the Carbon Capture, Utilization, and Storage (CCUS) value chain needs the evaluation of the consequences of possible accidental submarine CO 2 leakages, including releases having high flow rate and very long duration, as blowouts. An innovative procedure for the estimation of the effects of submarine blowouts in shallow water was developed, based on the integration of specific sub-models. A model for blowout simulation is used to predict the features of the source term. The fate of the submarine plume is then assessed. Finally, the atmospheric dispersion of the surfacing gas is simulated, to estimate damage distances. The application of the methodology to a set of case studies evidences that in extremely shallow water the threshold distances of the gas cloud dispersing in the air can be higher for CO 2 than for natural gas. However, when considering higher water depths, the release of CO 2 to the atmosphere is strongly attenuated by the dissolution of CO 2 in the water column. [ABSTRACT FROM AUTHOR]

Global radionuclide dispersion from Fukushima nuclear accident urged several countries to begin evaluating the radiation effects from neighboring countries. The representative data selection simulation is one of the evaluation methods providing practical results with reasonable computational resources. However, it is mostly used in the domestic radiation effect evaluation. This study investigated and modified this simulation method for transboundary radiation effect evaluation. The effects of selected area boundaries, optional weather parameters, and sampling rate, critical parameters in the representative data selection scheme, are sequentially investigated on the calculated results. The evaluation is performed by Nuclear Accident Consequence Analysis Code (NACAC) with hypothetical accidents at Fangchenggang NPP in China. It is revealed that area boundary and optional weather parameter selection insignificantly impact the predicted results, but the sampling rate condition affects the predicted results. Good agreements comprising dispersion characteristics and total effective dose equivalent by simulation using representative and sequential data selections are shown with absolute mean bias error lower than 2.4 × 10−3 mSv, root mean square error lower than 5.7 × 10−4 mSv, and correlation coefficient value higher than 9.1 × 10−1. [ABSTRACT FROM AUTHOR]

Growing interest in offshore geologic carbon sequestration (GCS) motivates risk assessment of large-scale subsea CO2 well blowouts or pipeline ruptures. For major leaks of CO2 from wells or pipelines, significant fluxes of CO2 may occur from the sea surface depending on water depth. In the context of risk assessment of human health and safety, we have used previously simulated coupled well-reservoir and water column model results as a source term for dense gas dispersion of CO2 above the sea surface. The models are linked together by one-way coupling, that is, output of one model is used as input to the next model. These first-of-their-kind coupled flow results are applicable to assessing the hazard of CO2 to people at and downwind of the sea surface location of emission. Hazard is quantified by plotting the downwind dispersion length (DDL), which we define in the study as the distances from the emission source to the point at which the emitted CO2 has been diluted to 5% and 1.5% in air by volume. Results suggest that large-scale blowouts in shallow water (10 m) may cause hazardous CO2 plumes extending on the order of several hundred meters downwind. Details of the modeling show DDL has a maximum for windspeed (at an elevation of 10 m) of approximately 5 m/s, with smaller DDL for both weaker and stronger winds. This is explained by the fact that wind favors transport but also causes dispersion; therefore there is a certain wind speed that maximizes DDL. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

The fast prediction of the extent and impact of accidental air pollution releases is important to enable a quick and informed response, especially in cities. Despite this importance, only a small number of case studies are available studying the dispersion of air pollutants from fires in a short distance (O(1 km)) in urban areas. While monitoring pollution levels in Southampton, UK, using low-cost sensors, a fire broke out from an outbuilding containing roughly 3000 reels of highly flammable cine nitrate film and movie equipment, which resulted in high values of PM2.5 being measured by the sensors approximately 1500 m downstream of the fire site. This provided a unique opportunity to evaluate urban air pollution dispersion models using observed data for PM2.5 and the meteorological conditions. Two numerical approaches were used to simulate the plume from the transient fire: a high-fidelity computational fluid dynamics model with large-eddy simulation (LES) embedded in the open-source package OpenFOAM, and a lower-fidelity Gaussian plume model implemented in a commercial software package: the Atmospheric Dispersion Modeling System (ADMS). Both numerical models were able to quantitatively reproduce consistent spatial and temporal profiles of the PM2.5 concentration at approximately 1500 m downstream of the fire site. Considering the unavoidable large uncertainties, a comparison between the sensor measurements and the numerical predictions was carried out, leading to an approximate estimation of the emission rate, temperature, and the start and duration of the fire. The estimation of the fire start time was consistent with the local authority report. The LES data showed that the fire lasted for at least 80 min at an emission rate of 50 g/s of PM2.5. The emission was significantly greater than a ‘normal’ house fire reported in the literature, suggesting the crucial importance of the emission estimation and monitoring of PM2.5 concentration in such incidents. Finally, we discuss the advantages and limitations of the two numerical approaches, aiming to suggest the selection of fast-response numerical models at various compromised levels of accuracy, efficiency and cost.

Many regulatory requirements add significant delay in the licensing of new nuclear power stations. One area of particular interest is the environmental impact of potential atmospheric release. The purpose of this research is to demonstrate effectiveness of meteorological data mining and synthesis from offsite locations to reduce need for onsite data, hence allowing rapid licensing. The automated procedures tested for data mining and extraction of meteorological data from multiple offsite sources and the data analytic tool developed for data fusion are presented here. Three important meteorological parameters from regulatory compliance are considered for this analysis: wind velocity, wind direction, and atmospheric stability. Callaway Nuclear Power Plant (CNPP) is used as our reference site. CNPP uses the ΔTΔz approach while we use the Vogt method to estimated stability for the offsite locations. Stability classification correlation coefficients between the reference plant and Columbia Regional Airport range from −0.087 to 0.826 for raw with an average of 0.317 ± 0.313. With travel time, correction changed slightly, i.e., a 10 m observation 0.064 ± 0.249 and 0.028 ± 0.123 and a 60 m observation 0.103 ± 0.265 and 0.063 ± 0.155 for the wind from the reference plant to the airport and vice versa, respectively. For Jefferson City Memorial Airport, raw data correlation was from −0.083 to 0.771, with an average of 0.358 ± 0.321. With travel time, correction changed slightly, i.e., 10 m observation 0.075 ± 0.208 and −0.073 ± 0.255 and 60 m observation 0.018 ± 0.223 and −0.032 ± 0.248 for wind from the reference plant to the airport and vice versa, respectively. Stability classification correlation coefficients between the reference plant and St. Louis Lambert International Airport ranged from −0.083 to 0.763 for raw with an average of 0.314 ± 0.295. With travel time, correction changed slightly, i.e., 10 m observation −0.003 ± 0.307 and −0.030 ± 0.277 and 60 m observation −0.030 ± 0.193 and −0.005 ± 0.215 for wind from the reference plant to the airport and vice versa, respectively. It is important to observe that mathematically. stability class correlation coefficients were not great, but in most cases the predicted and observed values were only off by one stability class. Similar correlations were calculated for wind direction and velocities. Our result, when applied to a proposed nuclear power station, can significantly reduce time and effort to prepare a robust environmental protection plan required for license application.

Aerobiology is a scientific discipline that focuses on investigating biological particles (bioaerosols) passively transported in the atmosphere, mainly fungal spores and pollen grains. Due to the allergic and pathogenic properties of these particles, aerobiological data is widely used in allergology, plant pathology, and agriculture. In addition, the results of aerobiological monitoring have found applications in biogeography, paleoecology, forestry, veterinary medicine, forensic science, and climate change research, as well as in the assessment of threats to the deterioration of cultural heritage. In this review, the contribution of Polish scientists to the development of worldwide aerobiology is presented. The most important results on the atmospheric dispersion of bioaerosols, spatiotemporal modeling, and novel methods used in aerobiological research are described. Moreover, the cooperation at the national and international levels as part of scientific programs and the perspectives for further development of aerobiology in Poland are discussed.

The advection-Diffusion Equation in three dimensions was solved using the Separation variable, Substitution and Laplace transform methods, taking into account that eddy diffusivity along the horizontal, lateral coordinates and wind velocity are constant respectively, while the vertical eddy diffusivity is a function of the vertical height z, Monin-Obukhov length L friction velocity at different emission rate and operation of iodine (I-131) in an unstable condition. We took the measured data from Inshas, Cairo, Egypt and compared the concentration of the calculated results with the results obtained from the solution equation at heights of 0.7, 27, and 43 meters. We found that all models are within a factor of two with the observed data from statistical evaluations in unstable conditions, we found that all models fell into a factor of two with the observed data. Whereas with NMSE and FB, the current models correlate better with the observed data. [ABSTRACT FROM AUTHOR]

Industrial sources emit airborne pollutants that impact health. Concentrations of these pollutants near emitting facilities vary according to local weather conditions but can frequently be high— especially at night. This study's methodology used historical hourly weather data and Pasquill air dispersion calculations to quantitatively model the dispersion and hourly concentrations of toxins at discreet distances and directions relative to the emitting source. The example used in this study is a natural gas compressor station's VOCs. This weather-based analytical methodology is applicable to almost any type of polluting site emitting any mix of airborne toxins. The objective was to estimate hourly concentration levels of airborne toxins, frequency of health-hazardous concentrations and therefore frequency of health risk to residents of varying sensitivities at discreet distances near an emitting source. A continuous air monitor confirmed the weather model's results. Based on EPA methodology and NIOSH data, this study provides charts that tabulate risk levels and frequency for individuals with varying sensitivities. Key findings include: 1. People in close proximity to toxin-emitting facilities are frequently exposed to health-hazardous air. 2. EPA's National Ambient Air Quality Standards (NAAQS) do not separately identify the high levels of toxins in close proximity to emitting facilities and therefore do not adequately protect the tens of millions of nearby residents. 3. A weather-based model can estimate exposure levels and the health-hazardous frequency for those in close proximity to most polluting facilities where emissions information is available.

The ash and gas released by large explosive volcanic eruptions rises to its neutral buoyancy level in the atmosphere, then spreads laterally to form an umbrella cloud. Density stratification of the atmosphere generates buoyancy forces in the cloud, which drive the outward spread. Although umbrella clouds are often modeled as circular axisymmetric structures, in practice they are usually influenced quite strongly by the meteorological wind, with spread in the upwind direction halted by the oncoming wind, and different rates of spreading in the downwind and crosswind directions. In this work, we derive a simple parametrization of non‐axisymmetric umbrella cloud spreading from a much more complex physically based shallow‐layer intrusion model. The new parametrization is quick to evaluate and so is suitable for use in operational Volcanic Ash Transport and Dispersion Models (VATDMs). In contrast to previous parametrizations, in which there is assumed to be no interaction between a circular umbrella cloud and the meteorological wind, here the umbrella cloud is influenced by the wind and adopts a shape determined by the balance of buoyant spreading and downwind drag forces. We apply the new scheme to four historical case studies of eruptions at Puyehue 2011, Pinatubo 1991, Ulawun 2019, and Calbuco 2015. The results are compared with VATDM simulations using a conventional circular umbrella cloud parametrization. Using the new scheme, good descriptions of cloud spread are recovered and the prediction of horizontal ash distribution is improved relative to the axisymmetric parametrization. Plain Language Summary: Erupting volcanoes eject a mixture of fine ash and gas, which rises into the upper atmosphere, where the ash presents a major hazard to jet aircraft. Large volcanic eruptions produce a giant cloud of ash, known as an umbrella cloud, which spreads horizontally. The spread of this umbrella cloud is driven by the variation in atmospheric density across its depth. Umbrella clouds are commonly assumed to be cylindrical, but in reality, they often assume a more complex shape, due to the influence of wind. In this paper, we derive a new mathematical model of umbrella cloud spreading that includes the effect of wind, which can be simulated on a computer quickly enough to produce practical forecasts of volcanic ash transport. The new model is applied to four historical eruptions and shown to produce good predictions of the umbrella cloud shape and extent in each case. Compared to existing cylindrical models, the distribution of ash inside the cloud is much improved. Key Points: A non‐axisymmetric parametrization of umbrella cloud spreading in wind is derived from a shallow‐layer intrusion modelThe new parametrization describes buoyancy‐driven spreading in both near‐circular umbrella clouds and in strongly wind‐blown plumesThe predictions of a Volcanic Ash Transport and Dispersion Model are improved by the new parametrization, compared to axisymmetric models [ABSTRACT FROM AUTHOR]

Spray drift is a major contributor to pesticide losses in the atmosphere leading to nontargeted ecosystem exposure. An overview of currently used ground-application spray drift models highlighted gaps in the description of the processes occurring during and after spraying. The ADDI-Spraydrift model was developed to bridge some of these gaps and provide a comprehensive, yet concise description of spray drift processes. The model is based on a random walk approach that describes droplet emission, dispersion and evaporation, ground deposition and canopy interception, and accounts for atmospheric stability regimes, and in-canopy turbulence. It predicts airborne concentration, canopy interception and deposition to the ground downwind from the sprayer. The sensitivity analysis to wind speed, active matter content, leaf angle, canopy height, leaf area index, ejection angle and velocity demonstrated the consistency of the model behaviour. The model was calibrated and evaluated against the Ganzelmeier et al. (1995) sedimentary spray drift data in vineyards. The model satisfactorily predicted droplets deposition to the ground downwind from the field boundary with a mean deviation between modelled and measured deposition of 1.3%. A discrepancy was observed at 3 and 5 m downwind from the field boundary attributed to the sensitivity to spraying conditions for which several hypotheses are discussed. Bearing in mind the need to explicitly describe the emitted droplet size and velocity, the overall predictive performance of the model appeared to be sufficient for assessing and comparing application techniques efficiency, quantifying pesticide loss and bystanders or resident exposure and evaluating the efficiency of mitigation measures. [Display omitted] • Model estimates spray drift and crop interception for ground sprayers. • Model is based on a random walk approach integrating spray drift key processes. • Model predictions are highly sensitive to droplet ejection characteristics. • Model predictions well represent Ganzelmeier drift experiments on vineyards. • Model is expected to be valuable for impact studies of spray drift. [ABSTRACT FROM AUTHOR]

In dual-wavelength free-space optical communication systems, the wavefront distortion differences caused by the wavelength difference of the signal and beacon lights cannot be completely corrected. In this study, according to the method of geometric optics, the relationship between the wavefront phases of the signal and beacon lights is analyzed by establishing a mathematical model of the cross-correlation ratio of the arrival-angle fluctuation and phase relationship of different Gaussian-beam wavelengths under weak turbulence near the surface. The numerical results show that after Gaussian beams of different wavelengths propagate through the same atmospheric channel, the cross-correlation number of the arrival-angle fluctuation decreases with an increase in the wavelength difference, waist radius, and turbulence intensity, and increases with an increase in propagation distance. The beam-wavefront phase difference increases with an increasing wavelength difference. Finally, a wavefront distortion correction experiment of a dual-wavelength adaptive optical system verified the correctness of the wavefront phase-difference relationship between the signal light and beacon light established in this study. [ABSTRACT FROM AUTHOR]

A comprehensive approach for modeling the pulse height spectra of gamma-ray detectors from passing radioactive cloud in a case of accident at NPP has been developed. It involves modeling the transport of radionuclides in the atmosphere using Lagrangian stochastic model, WRF meteorological processor with an ARW core and GFS data to obtain spatial distribution of radionuclides in the air at a given moment of time. Applying representation of the cloud as superposition of elementary sources of gamma radiation the pulse height spectra are calculated based on data on flux density from point isotropic sources and detector response function. The proposed approach allows us to obtain time-dependent spectra for any complex radionuclide composition of the release. The results of modeling the pulse height spectra of the scintillator detector NaI(Tl) Ø63x63 mm for a hypothetical severe accident at a NPP are presented.

Modern society is confronted with emerging threats from chemical, biological, and radiological (CBR) hazardous substances, which are intensively utilized in the chemical, medical, and energy industries. The atmospheric dispersion of released CBR hazardous pollutants can influence a large percentage of the population owing to their rapid process with extensive spatial coverage. It is important to comprehensively understand the behaviors of the released CBR pollutants in the atmosphere to fully evaluate the risks and protect public safety. In this study, we reviewed the advancements in the atmospheric transport of CBR pollutants, including the urban atmospheric boundary layer, unique concepts, and models for CBR pollutants. We underlined the development of innovative methodologies (e.g., inverse estimation and data assimilation methods) for the atmospheric transport of accidentally released CBR pollutants to reduce uncertainties in emissions and accumulated errors during dispersion by combining numerical models with monitoring data. Finally, we introduced progress in quantitative risk assessment, including exposure assessment and dose-response relationships for CBR hazardous pollutants. A framework, source, assimilation, fundamentals, exposure, and risk (SAFER), has been proposed to integrate the key components in the risk assessment of airborne CBR hazardous pollutants. These methods and models can contribute to effective risk preparedness, prevention, evidence-based policymaking, and emergency response to airborne CBR pollutants.

Numerical simulations of atmospheric dispersion and dose assessment were performed for the Jordan Research and Training Reactor (JRTR) to evaluate its radiological effects on surrounding population and the environment. A three-dimensional atmospheric dispersion model was applied to investigate the behavior of the radionuclides released into the air, and a dose assessment model was used to estimate the radiological impact on the population residing in nearby cities around the JRTR. Considering full core meltdown an accidental scenario, most of the source term was assumed to be released from the JRTR. Simulations were performed to calculate the air and deposition concentrations of radioactive materials for July 2013 and January 2014. The monthly averaged values of concentrations, depositions, and dose rates were analyzed to identify the most harmful effects in each month. The results showed that relatively harmful effects occurred in January 2014, and the total annual dose rate was estimated to be approximately 1 mSv outside the 10 km radius from JRTR. However, the impact of a nuclear accident is not as severe as it might seem, as the affected area is not highly populated, and appropriate protective measures can significantly reduce the radiation exposure. This study provides useful information for emergency preparedness and response planning to mitigate the radiological consequences of a nuclear accident at the JRTR. [ABSTRACT FROM AUTHOR]

There are certain spatial configurations in cities that generate areas with reduced ventilation where, consequently, air pollution can reach hazardous levels. Although urban forms have already been flagged as a factor affecting air pollution, its role in the accumulation of volatile organic compounds has not been extensively evaluated with field measurements. In order to investigate the effect of urban morphology on air pollution levels, we measured the concentration of benzene, toluene, ethylbenzene, and xylenes (BTEX) in 44 different city sites, using Radiello® diffusive passive samplers during a 1-week campaign. This work presents a method that maps a city in zones with different levels of atmospheric dispersion by analyzing the proportions of BTEX in the ambient air. The method applied to a coastal city (characterized by uniform wind patterns) revealed the existence of two clearly differentiated zones. In one of them, the mean benzene concentration was 3.26 times higher than in the other. However, the mean concentrations of the rest of BTEX were barely the same in both areas. These findings suggest that slow degradation pollutants (i.e., benzene) accumulate in poor ventilated areas, whereas faster degradation pollutants do not show accumulation. The conclusions of this study can be particularly useful in designing personal exposure assessments, optimizing the urban morphology, and improving the location of air quality monitoring stations. [ABSTRACT FROM AUTHOR]

The work describes the methodology and results of analysis for the consequences assessment of eruption from Cumbre Vieja volcano in Canary Islands. The preliminary analysis of dispersion of emitted pollutants was performed using Lagrangian trajectories model. To estimate long-term outcomes of eruption in terms of deposition and concentration of eruption products the Eulerian model of air dispersion was used. The model uses data from Global Forecasting System meteorological model launched at the NCEP-NOAA centre. The average concentration and deposition of sulfur compounds as well as the probability and time of the pollution cloud reaching all European capitals were examined. In 90 days a cloud of pollutants (SO2, volcanic ashes) spread over the northern hemisphere. Pollution reached Africa, North Sea and Europe. With an average emission of 15,000 tons of SO2/day, the maximum calculated deposition to the Earth’s surface reached 0.8g/m2, while overall deposition – 35 kilotons in the domain area.

This study is a contribution for radiation dose calculations of a hypothetical accident of a 1 MW research reactor Triga Mark II using HotSpot code. A postulated accidental release of noble gases and halogens were considered. The total effective dose (TED) was estimated for 1 day and 50 years after release. The total damage of fuel element cladding with a maximum radioactivity was considered. The obtained results show minimal TED values at the beginning of the release and at a shorter distance from the source. The maximum calculation results are acceptable and below the recommended public dose limit.

New Nuclear Power Plant (NPP), which is under construction in El Dabaa, Egypt, is expected to start working within few years. Such project should be associated with several scientific research works. The suitability of the NPP location as well as the assessment of the impact of its routine work and accidental failure is among the points that should be addressed. In this work, the contamination risks due to uniform accidental leakage of the radioactive aerosol C 137 s that continues for eight hours is studied. FLEXPART version 10.4 at high resolution (55 km) is applied using six-hour NCEP FNL (1° × 1°) gridded data to simulate the dispersion and deposition of C 137 s for the subsequent five days. This process is repeated each day for the period of 2008 to 2018. It is shown that high concentration and total deposition are observed particularly during the summer season. In addition, the consideration of different emission scenarios indicates that Egypt is expected to be strongly affected. Moreover, dispersion and concentration of the radioactive materials is notably influenced by near-surface winds. In conclusion, FLEXPART is considered as a promising tool to explore the possible nuclear hazards under a variety of meteorological conditions. Further, a future study will consider the influence of the horizontal grid spacing and lateral boundary condition using the coupled Weather Research and Forecasting (WRF)-FLEXPART system. [ABSTRACT FROM AUTHOR]

A screening assessment of the human health risk from nanocarbon materials, which are solid carbon species produced in carbon-free hydrogen production by methane decomposition, was conducted during the life cycle stages of steel utilization and landfill disposal. First, the scenario was established for the use in the steel industry of a substantial amount of nano-scale solid carbon as an alternative to pulverized coal injected into the blast furnace. Additionally, the scenario was set for landfill disposal of solid carbon. For these scenarios, atmospheric emission quantities during loading and unloading and during storage of solid carbon were estimated using existing emission scenario documents. The atmospheric concentration of solid carbon was estimated using a low-rise industrial source dispersion model. Finally, human health risks were evaluated and compared with the general environmental threshold of carbon nanomaterials in the surrounding area. The results indicated that the atmospheric concentrations of solid carbon around the steel plant and the landfill site did not exceed the environmental threshold by implementing possible emission reduction measures. [ABSTRACT FROM AUTHOR]

Finite volume fitted difference schemes are constructed for one and two-dimensional air-pollution models with degenerate vertical diffusion. A weak formulation of the equations imposes the boundary conditions naturally along the boundaries, where the equation becomes degenerate. Then, we establish the energy well-posedness of the initial-boundary value problems. We prove minimum principle and show that the solution cannot attains its minimum on the boundary of degeneration and this allows us to control the positivity of its solution. To overcome the degeneracy of the vertical diffusion, we perform a local fitted space discretization. Non-negativity of numerical solutions is proved. Numerical experiments are discussed. As examples, we apply the method to study the pollution concentration to Monin–Obukhov types atmospheric models. [ABSTRACT FROM AUTHOR]

Mining operations can contribute substantial amounts of pollution in the form of atmospheric dust. Statistical models predicting the spread of pollutants from these sources are useful for evaluating the environmental impacts of mines. Our study develops a mechanistic spatial model for heavy metal concentrations in Cape Krusenstern National Monument (CAKR), Alaska, USA. We characterize the spatial structure in our statistical model using a spatio‐temporal process for atmospheric dispersion. Mathematically, this is modeled using an advection‐diffusion partial differential equation that incorporates information about pollutant sources, diffusion, duration of spread, and advection (i.e., prevailing winds). Our approach improves upon previous statistical methods by including a temporally varying advection component and linking indirect concentration measurements to the spatio‐temporal dynamics in the model. We estimated concentrations of three heavy metals jointly using a Bayesian hierarchical model to account for the similarity in processes across chemicals. Our mechanistic statistical model is beneficial because it can predict chemical concentrations for scenarios where mining activities change. Additionally, our analysis provides an example of how using spatio‐temporal processes in statistical models for spatial data can incorporate understanding of mechanisms governing the spread of pollution and provide inferences for parameters associated with these processes. [ABSTRACT FROM AUTHOR]

Air pollution is one of the main environmental problems in the metropolitan area of São Paulo (MASP) in Brazil, with frequent exceedances of air quality standards. Occasionally, the exceedance events last many days, resulting in continuous exposure to concentrations above the standards, with impacts to human health. In this air pollution long-term study, a method was developed to identify persistent exceedance events (PEE) of particulate matter (PM10) and ozone (O3) and associated surface weather patterns. Between 2005 and 2017, 119 PEE were identified, with exceedances occurring simultaneously in at least 50% of monitoring stations along 3 to 14 consecutive days. Median PM10 and O3 concentrations increased by 60% during the events. Mean fields of sea level pressure from global reanalysis data revealed the influence of high-pressure systems and pre-frontal conditions. PM10 events were frequent in austral winter and mostly driven by anomalous atmospheric circulation with a wind change to northwest. On the other hand, O3 events were common in the spring, associated with higher positive anomalies of temperature and solar radiation. Overall, results show that PEE span a regional scale, differing from ordinary exceedance events that can be driven by local conditions. Policy makers should be aware of the frequency of PEE in the development of mitigation measures against the exposure to harmful levels of air pollutants. The concept of PEE can be applied to other metropolitan areas and may support the development of data-driven air quality predictive models based on current or forecasted weather conditions. [ABSTRACT FROM AUTHOR]

This paper aims to estimate the rate of particulate contaminants emitted by multiple sources, whose values are unknown, using the values identified by the receptors distributed around the sources. In a nuclear emergency with release of radionuclides into the atmosphere, in order to make the correct decision, it is necessary to identify the source term and its release rate, as well as the meteorological data, essential factors for defining the direction and size of the radioactive plume. For this purpose, a model of Particle Swarm Optimization (PSO) is applied together with a mathematical model of Gaussian dispersion, being created the program Particle Swarm Optimization Dispersion Model (PSODM).

The article consists, through a Severe Accident, evaluating the impact of radionuclides released into the atmosphere in the vicinity at Nuclear Power Plant. The source term used in present work is obtained by means of proportionality between Angra 1 and Angra 2. That is, the source term of Angra 2 is calculated based on its activity estimated from numbers of fuel pellets of both power plants and the already known activity of Angra 1. This calculation resulted in total activity of Angra 2 equivalent to 146.18% of activity of Angra 1. The results indicate that for severe accident scenarios, the protective measures to be adopted will be general emergency; and the impact area, which currently has a distance of 5 km, would become greater than this value.

This paper presents an integrated framework in which an air quality dispersion model is combined with an economic dispatch model to address the environmental tradeoffs of a cost-optimized fuel allocation strategy. A unit commitment dispatch model was developed to re-allocate fuel between power generation and desalination plants. Then, an air quality dispersion model was run for a 1-year period to simulate the spatiotemporal transport of pollutants and the possible formation of air pollution hotspots. The results showed that optimizing fuel allocation can reduce the associated fuel cost by as much as 16.5% of the total cost (1.08 billion USD). The optimized fuel allocation approach resulted in reducing the base case emissions of NOx, SO2, CO, and PM10 by 25%, 4.6%, 3.1%, and 7.6%, respectively. However, the air quality impact of the optimized fuel allocation scheme was not as favorable. The 1-h-averaged maximum concentration of SO2 increased, and NOx concentrations were slightly above the allowable limits. Although fewer pollutants were emitted over the study period in the optimized fuel allocation case, the variability in how fuel was allocated between power and desalination plants concentrated emissions near residential areas. As a result of this trend, the maximum 1-h concentrations of all pollutants increased, with increases ranging from 1% for CO to 29% for PM10. In addition, the total number of hourly SO2 concentration violations increased dramatically, leading to additional hotspot areas. Therefore, the effectiveness of any environmental-economic fuel dispatch strategy should be tested based on additional indicators such as the allowable limits of pollutant concentrations and not exclusively the overall emissions of the system. This approach could promote the selection of the most economic fuel dispatch method while simultaneously considering regional air quality impacts. [ABSTRACT FROM AUTHOR]

Volcanic ash transport and dispersion models (VATDMs) are necessary for forecasting tephra dispersal during volcanic eruptions and are a useful tool for estimating the eruption source parameters (ESPs) of prehistoric eruptions. Here we use Ash3D, an Eulerian VATDM, to simulate the tephra deposition from the ~ 7.7 ka climactic eruption of Mount Mazama. We investigate how best to apply a VATDM using the ESPs characteristic of a large magnitude eruption (M ≥ 7). We simplify the approach to focus on the distal deposit as if it were formed by a single phase of Plinian activity. Our results demonstrate that it is possible to use modern wind profiles to simulate the tephra dispersal from a prehistoric eruption; however, this introduces an inherent uncertainty to the subsequent simulations where we explore different ESPs. We show, using the well-documented distal Mazama tephra, that lateral umbrella cloud spreading, rather than advection–diffusion alone, must be included in the VATDM to reproduce the width of the isopachs. In addition, the Ash3D particle size distribution must be modified to simulate the transport and deposition of distal fine-grained (< 125 µm) Mazama ash. With these modifications, the Ash3D simulations reproduce the thickness and grain size of the Mazama tephra deposit. Based on our simulations, however, we conclude that the exact relationship between mass eruption rate and the scale of umbrella cloud spreading remains unresolved. Furthermore, for ground-based grain size distributions to be input directly into Ash3D, further research is required into the atmospheric and particle processes that control the settling behaviour of fine volcanic ash. [ABSTRACT FROM AUTHOR]

A flare stack is an indispensable device in the oil and gas industry for allowing the safe combustion of gases into the atmosphere, especially during emergencies. However, it is not ideal for the routine disposal of gaseous waste, as it is subject to meteorological influences and poor operational control. In addition, it can be affected by toxic currents and thus pose a potential risk of odors; in view of this, an assessment must be made of the implications of burning on the environment and health. Atmospheric dispersion modelling has proved to be a very useful tool for this purpose. In light of this, an attempt has been made in this work to evaluate the impact of H2S on the well-being (odor perception) of the community in the surrounding area of an oil refinery, where the temporary burning of rich gas in H2S occurs in a chemical flare, and operational factors have an influence on atmospheric dispersion. The odor assessment was carried out with the aid of AERMOD which was adapted to estimate the maximum odor concentration for very short periods by means of peak-to-mean ratios. The results showed that H2S detection can reach a probability rate of 42% at 3.5 km distance from the flare (in a time interval of 5 s) with a relatively high degree of annoyance (3.0 AU). However, some operational procedures can reduce the probability of odor detection to 29% and the degree of annoyance to 2.6 AU. [ABSTRACT FROM AUTHOR]

This study is a contribution for radiation dose calculations of a hypothetical accident of a 1 MW research reactor Triga Mark II using HotSpot code. A postulated accidental release of noble gases and halogens were considered. The total effective dose (TED) was estimated for 1 day and 50 years after release. The total damage of fuel element cladding with a maximum radioactivity was considered. The obtained results show minimal TED values at the beginning of the release and at a shorter distance from the source. The maximum calculation results are acceptable and below the recommended public dose limit. [ABSTRACT FROM AUTHOR]

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We studied the possibility of the combined application of screening models to assess the characteristics of sources in accidents at storage facilities for hazardous substances with complex models of atmospheric transport as part of modern decision support systems to calculate air pollution in a wide range of spatial and temporal scales. The evaporation time following an emergency spill, estimated by screening models, is used to set the emission intensity and calculate the atmospheric transport by the RODOS nuclear emergency response system. For the accident in Chernihiv on March 23, 2022, it was estimated that the maximum permissible concentration of ammonia 0.2 mg/m3 was exceeded at distances up to 75 km from the source. The dependence of the calculated maximum concentrations on time is close to asymptote Cmax ~ t-4.5 up to 15 h after emission, which is consistent with the asymptote σ ~ t 2/3 for the time dependence of the sizes of puffs following turbulent dispersion of instantaneous releases. [ABSTRACT FROM AUTHOR]

In dual-wavelength free-space optical communication systems, the wavefront distortion differences caused by the wavelength difference of the signal and beacon lights cannot be completely corrected. In this study, according to the method of geometric optics, the relationship between the wavefront phases of the signal and beacon lights is analyzed by establishing a mathematical model of the cross-correlation ratio of the arrival-angle fluctuation and phase relationship of different Gaussian-beam wavelengths under weak turbulence near the surface. The numerical results show that after Gaussian beams of different wavelengths propagate through the same atmospheric channel, the cross-correlation number of the arrival-angle fluctuation decreases with an increase in the wavelength difference, waist radius, and turbulence intensity, and increases with an increase in propagation distance. The beam-wavefront phase difference increases with an increasing wavelength difference. Finally, a wavefront distortion correction experiment of a dual-wavelength adaptive optical system verified the correctness of the wavefront phase-difference relationship between the signal light and beacon light established in this study.

Numerical simulations of atmospheric dispersion and dose assessment were performed for the Jordan Research and Training Reactor (JRTR) to evaluate its radiological effects on surrounding population and the environment. A three-dimensional atmospheric dispersion model was applied to investigate the behavior of the radionuclides released into the air, and a dose assessment model was used to estimate the radiological impact on the population residing in nearby cities around the JRTR. Considering full core meltdown an accidental scenario, most of the source term was assumed to be released from the JRTR. Simulations were performed to calculate the air and deposition concentrations of radioactive materials for July 2013 and January 2014. The monthly averaged values of concentrations, depositions, and dose rates were analyzed to identify the most harmful effects in each month. The results showed that relatively harmful effects occurred in January 2014, and the total annual dose rate was estimated to be approximately 1 mSv outside the 10 km radius from JRTR. However, the impact of a nuclear accident is not as severe as it might seem, as the affected area is not highly populated, and appropriate protective measures can significantly reduce the radiation exposure. This study provides useful information for emergency preparedness and response planning to mitigate the radiological consequences of a nuclear accident at the JRTR.

Micro-meteorological studies of urban flow and pollution dispersion often assume a neutral atmosphere and often the three-dimensional variation in temperature fields and flow around buildings is neglected in most building energy balance models. The aim of this work is to present the results of development and validation of a three-dimensional tool coupling thermal energy balance of the buildings and modelling of the atmospheric flow and dispersion in urban areas. To do so, a 3D microscale atmospheric radiative scheme has been developed in the atmospheric module of the computational fluid dynamics (CFD) code Code_Saturne adapted to detailed building geometries. The full coupling of the radiative transfer and fluid dynamics models has been validated with idealized cases. In this paper, our focus is to simulate and compare with measurements the diurnal evolution of the brightness surface temperatures and the momentum and energy fluxes for a neighborhood in the city center of Toulouse, in the southwest part of France. This is performed by taking into account the 3D effects of the flow around the buildings and all thermal exchanges, in real meteorological conditions, and compare them to aircraft infrared images and in situ measurements on a meteorological mast. The calculation mesh developed for the city center and the simulation conditions for the selected day of the field campaign are presented. The results are evaluated with the measurements from the Canopy and Aerosol Particles Interactions in TOulouse Urban Layer experiment (CAPITOUL). In addition, the second purpose of this work is to investigate a hypothetical release of passive pollutant dispersion in the same area of Toulouse under different thermal transfer conditions for the street and the buildings surfaces: neutral and 3D radiative transfer heating. The presence of heat transfer continually modifies the airflow field while the airflow in the neutral case reaches a stationary state. Compared to the neutral case, taking into account the thermal transfer enhances the turbulence kinetic energy and vertical velocity (especially at the roof level) due to buoyancy forces. The simulation results also show that the thermal effects considerably alter the plume shape. [ABSTRACT FROM AUTHOR]

We performed a screening evaluation of the human health risk posed by nanocarbon materials at the lifecycle stages of manufacturing and the use of the solid carbon generated in hydrogen manufacture by methane decomposition. We first estimated the atmospheric emission volumes of the solid carbon produced by small-, medium-, and large-scale hydrogen manufacturing plants. We then estimated the atmospheric emission due to tire wear, which largely contributes to the emission of solid carbon usage. Next, we estimated the atmospheric concentration of solid carbon in an atmospheric simulation using the METI–LIS model, which estimates the atmospheric distribution of a pollutant's concentration near methane decomposition factories. We also used the AIST–ADMER model that estimated the regional atmospheric distributions around central Tokyo, where the traffic volume is the highest nationally. Finally, we performed a screening evaluation of human health risk in the surrounding areas, considering the permissible exposure concentrations of solid carbon. Our study identified no risk concerns at small- and medium-scale factory locations equipped with high-efficiency particulate air (HEPA) filtration facilities. At large-scale factories installed with HEPA filters, these emissions likely remain within the factory site. Furthermore, we determined that emissions from tire wear pose no risk to human health. The surroundings of small- and medium-scale factory sites installed with HEPA filters posed no risk to human health. [ABSTRACT FROM AUTHOR]