Experimental work at the 1982 Dry Deposition Intercomparison Experiment (DDIEx) involved the use of optical particle counters for covariance estimates of dry deposition velocities of accumulation mode aerosols. Meteorological and particle flux observations are presented. Deposition velocity estimates exhibit scatter about zero. A formulation of the standard error of the deposition velocity estimator is derived and examined. Using this formulation, the observed deposition velocities are shown to be marginally significant. Using a case study, the correlation coefficient is examined and presented as an important statistic to the work. Humidity effects on the measurements are briefly examined. Recommendations are made for improvements in the instrumentation. / Graduation date: 1985

The role of nitric acid (HNO3) on the atmospheric corrosion of metals has so far received little or no attention. However, the last decades of decreasing sulphur dioxide (SO2) levels and unchanged HNO3 levels in many industrialized countries have resulted in an increased interest in possible HNO3-induced atmospheric corrosion effects. In this study a new method was developed for studying the corrosion effects of HNO3 on metals at well-defined laboratory exposure conditions. The method has enabled studies to be performed on the influence of individual exposure parameters, namely HNO3-concentration, air velocity, temperature and relative humidity, as well as comparisons with newly generated field exposure data. The corrosion rate and deposition rate of HNO3 on copper was shown to follow a linear increase with HNO3 concentration. The deposition velocity (Vd) of HNO3 increased up to an air velocity of 11.8 cm s-1. Only at a higher air velocity (35.4 cm s-1) the Vd on copper was lower than the Vd on an ideal absorbent, implying the Vd of HNO3 at lower air velocities to be mass-transport limited. Within the investigated temperature range of 15 to 35 ºC only a minor decrease in the HNO3-induced copper corrosion rate could be observed. The effect of relative humidity (RH) was more evident. Already at 20 % RH a significant corrosion rate could be measured and at 65 % RH the Vd of HNO3 on copper, zinc and carbon steel reached maximum and nearly ideal absorption conditions. During identical exposure conditions in HNO3-containing atmosphere, the corrosion rate of carbon steel was nearly three times higher than that of copper and zinc. The HNO3-induced corrosion effect of copper, zinc and steel turned out to be significantly higher than that induced by SO2 alone or in combination with either NO2 or O3. This is mainly attributed to the much higher water solubility and reactivity of HNO3 compared to SO2, NO2 and O3. Relative to SO2, zinc exhibits the highest sensitivity to HNO3, followed by copper, and carbon steel with the lowest sensitivity. Extrapolation of laboratory data to an assumed average outdoor wind velocity of 3.6 m s-1 enabled a good comparison with field data. Despite the fact that ambient SO2 levels are still much higher than HNO3 levels, the results show that HNO3 plays a significant role for the atmospheric corrosion of copper and zinc, but not for carbon steel. The results generated within this doctoral study emphasize the importance of further research on the influence of HNO3 on degradation of other materials, e.g. stone and glass, as well as of other metals.

<p>The role of nitric acid (HNO₃) on the atmospheric corrosion of metals has so far received little or no attention. However, the last decades of decreasing sulphur dioxide (SO₂) levels and unchanged HNO₃ levels in many industrialized countries have resulted in an increased interest in possible HNO₃-induced atmospheric corrosion effects. In this study a new method was developed for studying the corrosion effects of HNO₃ on metals at well-defined laboratory exposure conditions. The method has enabled studies to be performed on the influence of individual exposure parameters, namely HNO₃-concentration, air velocity, temperature and relative humidity, as well as comparisons with newly generated field exposure data.</p><p>The corrosion rate and deposition rate of HNO₃ on copper was shown to follow a linear increase with HNO3 concentration. The deposition velocity (Vd) of HNO₃ increased up to an air velocity of 11.8 cm s^-1. Only at a higher air velocity (35.4 cm s^-1) the Vd on copper was lower than the Vd on an ideal absorbent, implying the Vd of HNO3 at lower air velocities to be mass-transport limited.</p><p>Within the investigated temperature range of 15 to 35 ºC only a minor decrease in the HNO₃-induced copper corrosion rate could be observed. The effect of relative humidity (RH) was more evident. Already at 20 % RH a significant corrosion rate could be measured and at 65 % RH the Vd of HNO₃ on copper, zinc and carbon steel reached maximum and nearly ideal absorption conditions.</p><p>During identical exposure conditions in HNO_3-containing atmosphere, the corrosion rate of carbon steel was nearly three times higher than that of copper and zinc. The HNO₃-induced corrosion effect of copper, zinc and steel turned out to be significantly higher than that induced by SO2 alone or in combination with either NO₂ or O₃. This is mainly attributed to the much higher water solubility and reactivity of HNO3 compared to SO₂, NO₂ and O_3. Relative to SO₂, zinc exhibits the highest sensitivity to HNO₃, followed by copper, and carbon steel with the lowest sensitivity.</p><p>Extrapolation of laboratory data to an assumed average outdoor wind velocity of 3.6 m s-1 enabled a good comparison with field data. Despite the fact that ambient SO₂ levels are still much higher than HNO₃ levels, the results show that HNO₃ plays a significant role for the atmospheric corrosion of copper and zinc, but not for carbon steel. The results generated within this doctoral study emphasize the importance of further research on the influence of HNO₃ on degradation of other materials, e.g. stone and glass, as well as of other metals. </p>

O transporte de minério em tubos é feito em larga escala não somente em longas distâncias, (através de minerodutos); como também dentro da mina, seja no trajeto entre a mina e a usina, como no caso de minerais lavrados por desmonte hidráulico, ou entre as operações unitárias dentro da usina de beneficiamento. O projeto dos sistemas de bombeamento de polpas requer o conhecimento das variáveis de escoamento, a perda de carga (&#916;P) e a velocidade de deposição (Vd). Discutem-se aqui alguns modelos de predição para tais variáveis. Apesar da irrefutável importância deste tipo de transporte, ainda não há consenso sobre a validade dos modelos existentes. Este trabalho teve como objetivo a análise comparativa dos modelos de velocidade de deposição propostos por Durand e Condolios (1952), Wasp et al. (1977) e Wilson et al. (2006), e os modelos de perda de carga propostos por Durand e Condolios (1952), Wasp et al. (1977) e Newitt et al. (1955) com os resultados de laboratório. A acurácia dos modelos, apesar das limitações de cada um, é crucial para que as variáveis de projeto do sistema de bombeamento sejam estabelecidas por meio do uso desses modelos. A comparação foi baseada em ensaios realizados em três test loops de diâmetros de 2\", 3\" e 4\" com minério de ferro, carbonatito e areia, em concentrações de sólidos de 15%, 30% e 50%. Trabalhando com minérios de diferentes granulometrias, densidades e polpas com concentrações diferentes pudemos analisar a interferência desses parâmetros no escoamento e no uso dos modelos propostos. Os modelos de Vd se mostraram bastante úteis, sendo que o modelo proposto por Durand e Condolios (1952) teve as melhores correlações para todos os materiais estudados. Já os modelos de perda de carga não mostraram correlações aceitáveis com os resultados de laboratório, endossando as indicações de alguns autores, como Chaves (2012) e Abulnaga (2002) que não recomendam o uso de modelos de predição de perda de carga nos cálculos de dimensionamento destes sistemas. Como alternativa, é possível utilizar plantas piloto e ensaios laboratoriais. / Ore transportation in pipes is carried out on a large scale not only at long distances, such as ore pipelines, but also within the mine, or in the path between the mine and the plant, as the case of minerals drawn by hydraulic dismantling, or between operations within the beneficiation plant. The design of the slurry pumping systems requires the knowledge of the flow variables, as the head loss (&#916;P) and the deposition velocity (Vd). Some prediction models for such variables are discussed in this dissertation. Despite the irrefutable importance of this type of transportation, there is still no agreement on the validity of the existing models. Their limitations make unfeasible to use them, and much more is necessary to improve in this field. This work aimed to make a comparative analysis of the deposition velocity models proposed by Durand and Condolios (1952), Wasp et al. (1977) and Wilson et al. (2006), and the head loss models proposed by Durand and Condolios (1952), Wasp et al. (1977) and Newitt et al. (1955) with laboratory results. The accuracy of the models, despite the limitations of each one, is crucial if pumping system design variables are established using these models. The comparison was based on laboratory tests performed on three diameter test loops, 2 \", 3\" and 4 \" with iron ore, carbonatite and sand a concentrations of 15%, 30% and 50% in weight solids concentrations. Working with different ore grain sizes and densities ores and pulps with different concentrations we can analyze the interference of these parameters in the flow and in the models use. The Vd models were very useful, and the Durand and Condolios (1952) model showed the best correlations for all ores studied. However, the head loss models did not show acceptable correlations with the laboratory results, endorsing the indications of some authors, such as Chaves (2012) and Abulnaga (2002), who do not recommend the use of prediction models for head loss in these systems sizing. Alternatively, it is possible to use pilot plants and laboratory tests.

O transporte de minério em tubos é feito em larga escala não somente em longas distâncias, (através de minerodutos); como também dentro da mina, seja no trajeto entre a mina e a usina, como no caso de minerais lavrados por desmonte hidráulico, ou entre as operações unitárias dentro da usina de beneficiamento. O projeto dos sistemas de bombeamento de polpas requer o conhecimento das variáveis de escoamento, a perda de carga (&#916;P) e a velocidade de deposição (Vd). Discutem-se aqui alguns modelos de predição para tais variáveis. Apesar da irrefutável importância deste tipo de transporte, ainda não há consenso sobre a validade dos modelos existentes. Este trabalho teve como objetivo a análise comparativa dos modelos de velocidade de deposição propostos por Durand e Condolios (1952), Wasp et al. (1977) e Wilson et al. (2006), e os modelos de perda de carga propostos por Durand e Condolios (1952), Wasp et al. (1977) e Newitt et al. (1955) com os resultados de laboratório. A acurácia dos modelos, apesar das limitações de cada um, é crucial para que as variáveis de projeto do sistema de bombeamento sejam estabelecidas por meio do uso desses modelos. A comparação foi baseada em ensaios realizados em três test loops de diâmetros de 2\", 3\" e 4\" com minério de ferro, carbonatito e areia, em concentrações de sólidos de 15%, 30% e 50%. Trabalhando com minérios de diferentes granulometrias, densidades e polpas com concentrações diferentes pudemos analisar a interferência desses parâmetros no escoamento e no uso dos modelos propostos. Os modelos de Vd se mostraram bastante úteis, sendo que o modelo proposto por Durand e Condolios (1952) teve as melhores correlações para todos os materiais estudados. Já os modelos de perda de carga não mostraram correlações aceitáveis com os resultados de laboratório, endossando as indicações de alguns autores, como Chaves (2012) e Abulnaga (2002) que não recomendam o uso de modelos de predição de perda de carga nos cálculos de dimensionamento destes sistemas. Como alternativa, é possível utilizar plantas piloto e ensaios laboratoriais. / Ore transportation in pipes is carried out on a large scale not only at long distances, such as ore pipelines, but also within the mine, or in the path between the mine and the plant, as the case of minerals drawn by hydraulic dismantling, or between operations within the beneficiation plant. The design of the slurry pumping systems requires the knowledge of the flow variables, as the head loss (&#916;P) and the deposition velocity (Vd). Some prediction models for such variables are discussed in this dissertation. Despite the irrefutable importance of this type of transportation, there is still no agreement on the validity of the existing models. Their limitations make unfeasible to use them, and much more is necessary to improve in this field. This work aimed to make a comparative analysis of the deposition velocity models proposed by Durand and Condolios (1952), Wasp et al. (1977) and Wilson et al. (2006), and the head loss models proposed by Durand and Condolios (1952), Wasp et al. (1977) and Newitt et al. (1955) with laboratory results. The accuracy of the models, despite the limitations of each one, is crucial if pumping system design variables are established using these models. The comparison was based on laboratory tests performed on three diameter test loops, 2 \", 3\" and 4 \" with iron ore, carbonatite and sand a concentrations of 15%, 30% and 50% in weight solids concentrations. Working with different ore grain sizes and densities ores and pulps with different concentrations we can analyze the interference of these parameters in the flow and in the models use. The Vd models were very useful, and the Durand and Condolios (1952) model showed the best correlations for all ores studied. However, the head loss models did not show acceptable correlations with the laboratory results, endorsing the indications of some authors, such as Chaves (2012) and Abulnaga (2002), who do not recommend the use of prediction models for head loss in these systems sizing. Alternatively, it is possible to use pilot plants and laboratory tests.

Pour les besoins du refroidissement de leurs réacteurs, les CNPE1 sont placés à proximité immédiate de cours d’eau ou du littoral. Ils sont de ce fait exposés à des bancs de brouillards, en particulier à l’automne et au cours de l’hiver. Or les modèles opérationnels de dispersion atmosphérique/dépôt, utilisés pour simuler la contamination radioactive de l’environnement à la suite d’un accident nucléaire, considèrent uniquement les dépôts par temps sec et ceux par temps de pluie. Faut-il tenir compte de la présence des brouillards comme terme additionnel de dépôt de radionucléides en cas d’accident nucléaire ? Pour répondre à cette question, une étude expérimentale a été conduite sur plusieurs sites exposés aux brouillards ou aux nuages (principalement la plateforme d’observation atmosphérique de l’ANDRA à Houdelaincourt ainsi que la station de recherche atmosphérique de l’OPGC/CNRS2 au sommet du Puy de Dôme et la plateforme d’étude atmosphérique SIRTA3 de l’IPSL4 à Palaiseau). La collecte d’eau de brouillard et la mesure des quantités d’eau déposées sous forme de gouttelettes sur différents types de végétaux, ont été réalisées respectivement grâce à collecteurs à fils et des pesées de précision. En mesurant le contenu en eau liquide dans l’air ainsi que la masse d’eau déposé sur les plantes, il a été possible de calculer des vitesses de dépôt des gouttelettes de brouillard pouvant atteindre plusieurs dizaines de cm.s-1 dans le cas d’un brouillard composé de grosses gouttelettes (diamètre médian volumique moyen de 20 µm). Ces vitesses élevées mettent en évidence l’importance des processus gravitationnels mais aussi turbulents notamment dans le cadre du dépôt sur des végétaux à structure foliaire tridimensionnelle comme les conifères. L’effet d’auto-écrantage lié à une densité de biomasse foliaire élevée a également été quantifié. Les concentrations en radionucléides à l’état de traces ont montré que l’eau de brouillard pouvait être jusqu’à 20 fois plus concentrée que l’eau de pluie, du fait de la dilution par condensation de vapeur d’eau sur les gouttelettes au cours de leur grossissement. Les mesures des masses d’eau déposées par les brouillards et de la concentration en radionucléides dans les gouttelettes sur le site d’Houdelaincourt, permettent d’estimer ces dépôts habituellement qualifiés d’occultes car trop faibles pour être quantifiés par des pluviomètres ou des radars météorologiques. Sur l’ensemble d’une saison de brouillard, le dépôt occulte de radionucléides a représenté jusqu’à 25% des dépôts par temps secs et par temps de pluie. En cas de rejet accidentel, la présence de brouillard pourrait contribuer à hauteur de 14% du dépôt par temps sec. Ces résultats mettent en évidence la nécessité de prendre en compte ce processus de dépôt pour mieux quantifier les retombées radioactives sur des territoires en contact avec des brouillards ou des nuages (en ce qui concerne les sites d’altitudes), en particulier en situation post-accidentelle. Un schéma simple de type dépôt sec, considérant le diamètre médian des gouttelettes dérivé de la visibilité, permet à minima de mieux simuler le processus de dépôt par sédimentation des gouttelettes. Ces travaux restent à compléter pour quantifier la contribution de la turbulence induite par l’écoulement de l’air au voisinage des obstacles comme des végétaux de grandes tailles et incorporer un schéma spécifique dans les modèles de dépôt. / For the purpose of cooling off their reactors, nuclear power plants are located near rivers, ponds or in coastal areas. In temperate regions and during fall and winter, they are frequently exposed to fogs. Operational models of atmospheric dispersion and deposition used to estimate radioactive contamination of the environment after a nuclear accident, consider dry deposition and wet deposition by rain. Should we take into account the deposition by fog droplets as an additional process in term of deposition? To answer this question, an experimental study has been setup on several sites often exposed to fogs or clouds. Fogwater collection and measurement of fogwater deposited on plants were realized with string collectors and precision balances, respectively. Different plant types were used for this study: small conifers, cabbage, grass plus a bare soil as a reference deposition surface. By measuring the liquid water content (LWC) and the mass of water deposited on plants, fog droplet deposition velocities can be calculated. In the case of fog composed mainly of big droplets (mean median volume diameter of 20 µm), deposition velocities of these droplets can reach several tens cm.s-1. These high deposition velocities highlight the fact that gravitational but also turbulent processes are both contributing to the deposition on plants especially with a tri-dimensional structure such as conifers. The edge effect linked to a strong density of trees has also been identified and quantified during our experiments. The radionuclides found in trace amounts in fogwater showed that fogwater could be up to twenty times more concentrated in radionuclides than rain water. It is due to the activity dilution during the condensation phase of the droplets, when the droplets are growing. Based on measurements of the mass of water deposited by fog and concentrations of radionuclides in fog droplets on the site of Houdelaincourt, occult deposition that cannot be quantify by rain gauges or meteorological radar can be estimated. Over a whole season of fog, occult deposition can represent up to 25% of the total deposition (dry and wet by rain) of radionuclides. In case of an accidental release, fog could contribute to 14% of the total deposition if no rain event occurs. Those results highlight the fact that fog deposition should be considered to better quantify radioactive fallouts in areas embedded by fog (or clouds for high altitude sites), particularly in post-accident situation. A simple model of dry deposition to simulate the droplets deposition by sedimentation can be developed, using the median diameter of droplets derived from the visibility. This work still needs to be completed to quantify the turbulence contribution induced by the air flow near obstacles such as large plants and to implement a specific scheme into deposition model.

Actuellement, le dépôt sec d’aérosols en milieu urbain est peu connu du fait d’un manque de données.Ces connaissances sont pourtant indispensables pour comprendre les flux de polluants dans les villes et estimer l’exposition d’habitants à des rayonnements ionisants dans le cas d’aérosols radioactifs. Un apport de données permettrait en outre d’améliorer la modélisation du dépôt dans ce milieu. Une approche expérimentale originale est employée pour étudier le dépôt sec d’aérosols submicroniques sur des surfaces urbaines. L’association d’expérimentations en soufflerie et in situ et l’utilisation de traceurs permettent de mesurer des vitesses de dépôt sec et d’étudier les différents phénomènes physiques qui régissent ce dépôt en milieu urbain. Ces données sont associées à des conditions de météorologie et de turbulence quantifiées par des mesures. Cet ensemble permet de hiérarchiser l’influence des principaux phénomènes physiques pour chaque type d’expérimentation. Notamment,des phénomènes différents doivent être considérés prépondérants dans le cas d’expositions chroniques ou aigües des surfaces urbaines aux particules atmosphériques. / Aerosol dry deposition is not much known for urban areas due to the lack of data. Knowledge on this phenomenon is necessary to understand pollutant fluxes in cities and to estimate inhabitant exposition to ionizing radiation of radioactive aerosols. A data providing could enable to enhance dry deposition models for these areas. An original experimental approach is performed to study submicron aerosol dry deposition on urban surfaces. Wind tunnel coupled to in situ experiments give results to study different physical phenomen on governing dry deposition. Dry deposition velocities are measured using aerosol tracers. These data are associated to turbulent and meteorological measured conditions. This database permits to classify the principal physical phenomenon for each experiment type. Finally, different phenomenon must be considered for chronic and acute exposition of urban surfaces to atmospheric particles.

No description available.

In the event of a radioactive release in an urban environment the consequent response mustbe swift and precise. As soon as first responders have correct information, they can make anaccurate risk assessment. However, if the position, release rate and time of the radioactiverelease is unknown it is hard to know how the pollutant will spread. This thesis aims to testa model which approximates these three unknowns using weather data (wind and rain) as wellas measurement data collected at sensors placed around an urban environment. An atmospheric dispersion model based on an existing Reynolds Averaged Navier-Stokes modelis set up in two geometries of different complexity to create forward mode synthetic depositiondata and adjoint mode concentration fields resulting from a fixed dry deposition velocity andscavenging effect for wet deposition. Variations of time- and space-dependent rainfall is simu-lated. The resulting data is used in an existing optimization model, where a parameter studyis conducted regarding regularization coefficients. This thesis shows that the optimization model accurately estimates position and its approximaterelease rate of a 2D geometry of radioactive releases using a logarithmic optimization approach,and fail to do so using a linear optimization approach. The logarithmic optimization model alsoapproximately estimates position and release rate in a 3D geometry. Regularization parametersshould be within the range of 0.1 and 1.2 depending on rain. More rain requires smallerparameters and will estimate a lower release rate. Time-dependent rainfall is shown to have amajor negative effect on simulation time.iii