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Dissertations / Theses on the topic 'Effect of radioactive pollution on'

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Published: 4 June 2021

Last updated: 1 August 2024

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1

Dale, Paul Geoffrey. "The effect of applying potassium as a countermeasure against radiocaesium in organic soils." Thesis, University of Stirling, 2000. http://hdl.handle.net/1893/12226.

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Following the Chernobyl accident in 1986, a range of countermeasures has been developed to reduce the transfer of 137Cs from soil to plant and from the plant into grazing animals. One such countermeasure is the application of potassium to the soil. However, little is known of any side-effects such an application may have on the ecosystem, the longevity of the application and the effectiveness in a range of soil types. An application of potash (KCl) was made to four organic upland soils in Cumbria. England at two application rates of 100 and 200 kg K ha-1 in June 1997 and at a single site in June 1998. Following application. a range of parameters within the ecosystem were recorded, through the collection of monthly samples of sail, vegetation and water samples over a period of fifteen months. The results indicate that the application was effective for at least one year following application, that a lag phase existed between potash application and any effect within each ecosystem and that the duration of this phase was site specific. The results also showed that the countermeasure was effective at all sites and there was little apparent difference between the two application rates. The parameters measured which included soil pH, plant biomass, changes in Cu, K, Mg, Mn and Ca concentrations within the soil and vegetation indicated only a relatively small effect of the application on the ecosystem as a whole. The application can be considered as a viable option for reducing the transfer of 137Cs from soil to plant. The study also shows that the effectiveness of the application is dependent on the measurement used. i.e. concentration ratios, Tag values or a total flux approach. It is argued that the flux approach is the most appropriate basis for comparing the effectiveness of potash as a countermeasure between several sites.

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2

Burnfield, Daniel L. "An advanced system for quantifying the effects of radiological releases following a major nuclear accident." Master's thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-03302010-020420/.

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3

Echevarria, Guillaume. "Contribution à la prévision des transferts sol-plante des radionucléides." Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL116N.

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Les calculs de sureté des stockages de déchets radioactifs nécessitent de connaitre le comportement d'un grand nombre de radionucléides dans les systèmes sol-plante cultivés. De plus, ils doivent intégrer les variations à long terme du climat et leur influence sur ces comportements. Afin de préciser les mécanismes et de prévoir les transferts sol-plante des radionucléides, trois éléments, représentant des comportements très contrastés, ont été choisis: 63Ni, élément fréquent dans les sols et de mobilité moyenne, 99Tc, élément artificiel et de grande mobilité et 94Nb, peu présent dans les sols et de très faible mobilité. Une céréale (blé d'hiver) et deux espèces fourragères (ray-grass anglais et trèfle violet) ont été cultivées en présence des radionucléides sur des sols développés sur des roches mères calcaires à différentes altitudes (bassin parisien et jura) en faisant varier les conditions de température. Pour 63Ni, il est démontré que la plante prélève l'élément dans le pool des ions Ni isotopiquement échangeables. La caractérisation de la mobilité comme de la biodisponibilité du radionucléide peut donc se faire par la méthode des cinétiques d'échange isotopique. Les facteurs de transfert (FT) sont inversement proportionnels à la taille du pool de nickel isotopiquement échangeable du sol. Les résultats confirment la très forte mobilité de 99Tc dans le système sol-plante par l'identité de comportement entre 99TcO4- et NO-3. Les FT atteignent 450 selon l'espèce, l'organe, le rendement et le niveau de fertilité azotée. Enfin, Nb n'est pas retrouvé dans la plante, en relation avec sa forte affinité pour la phase solide des sols (Kd élevés). L’effet général du refroidissement du climat est une diminution du transfert sol-plante des trois modèles de radionucléides. Il a été possible de modéliser l'absorption des radionucléides par les plantes (modèle uptake) à partir de la caractérisation de leur fraction assimilable dans le sol par la méthodologie définie dans ce travail. L’outil de modélisation permet de déterminer les facteurs du comportement des radionucléides responsables du transfert vers la plante. Il autorise aussi, par la mise en œuvre de techniques rapides, la quantification systématique du transfert sol-plante des radionucléides

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4

Fraysse, Benoit. "Caractérisation de mollusques dulçaquicoles en tant que bioindicateurs de radiocontamination dans un contexte de multipollution métallique (Cd, Zn)." Bordeaux 1, 2001. http://www.theses.fr/2001BOR12379.

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La problématique dans laquelle s'insère ce travail de recherche est l'étude des bioindicateurs de radiocontamination des milieux aquatiques continentaux, dans un contexte de multipolution métallique. Les métaux, tels que le cadmium (CD) et le zinc (zn), sont présents dans un nombre croissant d'hydrosystèmes, à des concentrations susceptibles d'induire des effets physiologiques. Cette exposition chronique aux métaux génére des perturbations métaboliques et comportementales des individus, et peut induire l'activation de mécanismes de détoxication. Le principal objectif de recherche à été d'estimer les conséquences de la présence de ces métaux sur la bioaccumulation de radionucléides (57Co, 110m Ag, 134 Cs) par deux espèces de bivalves (Corbicula fluminea et dreissena polymorpha), en terme de niveau de contamination, de cinétique de transfert et de distribution tissulaire des radionucléides. Du fait du caractère exploratoire de cette étude, deux thèmes ont été développés : (i) la vérification in situ de la pertinence de la problématique, et (ii) l'analyse des mécanismes d'interaction métal/ radionucléide en conditions controlées et standardisées (laboratoire). Pour les différentes conditions expérimentales étudiées (laboratoire et terrain), nous avons montré que la pré ence de métaux dans le milieu perturbe la bioaccumulation des radionucléides par des bivalves d'eau douce, notamment par une réduction du niveau de contamination des organismes par les radionucléides, une réduction de leur vitesse d'accumulation et une augmentation de leurs vitesses d'élimination, et modifi cation de leur distribution tissulaire et cellulaire.

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5

Salih, Isam M. Musa. "Radon in natural waters : Analytical Methods; Correlation to Environmental Parameters; Radiation Dose Estimation; and GIS Applications." Doctoral thesis, Linköpings universitet, Medicinsk radiofysik, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5221.

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Investigations of radon in natural water and its relation to physical and chemical parameters are outlined in this thesis. In particular, a method for measuring 222Rn in water at low concentrations (~20 mBq.l-1) is described, followed by discussions concerning the design and its application to study both radon and parameters influencing radon levels in natural waters. A topic considered is the impact of fluoride and other aquatic parameters on radon in water. Moreover, variables such as uranium series radionuclides and stable elements in water, bedrock and sediment radioactivity and geology are investigated in two case studies. This was performed by employing radiometric-, chemical-, statistical- and GIS & geostatistical- analyses. The general water chemistry and presence of some elements such as fluoride was observed to influence radon levels in water. Health aspects of radon in drinking water are discussed based on radiation dose assessments. The radiation doses are compared with and added to doses incurred from ingestion of uranium, radium and polonium isotopes in drinking water and inhalation of radon in air in order to estimate total exposures for different age categories. The results may have a potential for future epidemiological studies.

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6

Perrier, Thomas. "Etude théorique et expérimentale du comportement biogéochimique de l'Américium-241 en conditions rhizosphériques simplifiées : application dans un sol agricole calcaire." Nancy 1, 2004. http://www.theses.fr/2004NAN10058.

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Cette étude a recherché les processus biogéochimiques qui contrôlent la migration de l'241Am dans la rhizosphère de sols agricoles. Des tests de lixiviation ont été effectués sur des colonnes remplies d'un sol naturel calcaire remanié, artificiellement contaminé en Am, avec plusieurs solutions contenant du citrate et/ou du glucose pour simuler des exsudats racinaires. Les résultats montrent une remobilisation de l'Am contrastée : infime pour une solution en équilibre avec le sol ou contenant des concentrations d'exsudats de 10-4 M, faible lors d'un apport conséquent de glucose, mais 300 à 10000 fois plus importante en présence de citrate à >10-2 M avec ou sans glucose, en complexant l'Am libéré en solution après dissolution des phases porteuses. Du transport colloi͏̈dal d'Am significatif est systématiquement observé. La complexité et l'inter-connexion des processus est montrée et des pistes de modélisation sont discutées à l'aide d'une base de données thermodynamiques spécifique
Our research investigated the relevant biogeochemical processes controlling 241Am migration in the rhizosphere of agricultural soils. Lixiviation tests were performed on columns packed with calcareous soil artificially contaminated with Am, with various solutions containing citrate and/or glucose to simulate root exudates. Results show contrasted Am releases: minute for a solution in equilibrium with the soil or containing 10-4 M concentrations in exudates, small for important glucose supply, they were 300 to 10000 greater with citrate at >10-2 M with or without glucose, by complexing Am released in solution after the dissolution of carrier phases. Significant Am colloidal transport was also systematically observed. The complexity and inter-connectivity of the processes are pointed out and modelling directions are discussed on the basis of a specific thermodynamical database

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7

Smati, Abdenasser. "Contribution à l'étude des transferts de chaleur et de masse dans le matériau de remplissage d'un stockage de déchets haute activité." Paris 6, 1986. http://www.theses.fr/1986PA066143.

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La connaissance des phénomènes d'hydratation du matériau de remplissage est essentielle pour une prédiction des transferts dans les barrières ouvragées des stockages de déchets radioactifs en milieu géologique. On a développé, dans le cas isotherme, une méthode thermique de mesure continue de l'humidité sur des échantillons d'argile compactée. Cette méthode a été utilisée pour déterminer le coefficient de diffusion et la perméabilité d'un matériau argileux non gonflant (kaolinite). Son application à la bentonite (smectite) demande des développements supplémentaires du fait de la complexité du comportement de ce matériau.

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8

Beaumont, Marie-Pier. "Utilisation d'un bio-indicateur pour le suivi des rejets radioactifs aqueux de la centrale nucléaire Gentilly-2." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27362/27362.pdf.

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Pour évaluer l’impact environnemental de rejets industriels, des bio-indicateurs sont fréquemment utilisés. Dans le cas des rejets radioactifs aqueux d’une centrale nucléaire, les moules pourraient être de bons bio-indicateurs en raison des grands volumes d’eau qu’elles filtrent. Dans le cadre de ce projet, l’espèce de moules Elliptio complanata a été choisie pour étudier les rejets radioactifs aqueux de la centrale nucléaire Gentilly-2. Puisque cette centrale est de type CANDU et qu’elle rejette principalement du tritium et du carbone-14 dans l’environnement, ce sont ces deux radionucléides qui ont fait l’objet du suivi dans les moules. Pour cette étude, des centaines de moules ont été placées dans le panache des rejets aqueux de la centrale. Deux systèmes ont été utilisés : des cages positionnées à faibles distances de la source du rejet et un aquarium installé au début du rejet. Les concentrations de tritium et de carbone-14 ont été mesurées dans les moules après leur exposition, grâce à différents traitements physiques et chimiques préalables aux dosages. Les résultats des analyses montrent que les moules ayant séjourné dans les eaux de rejet de la centrale sont peu affectées par le tritium et par le carbone-14.

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9

Jamil, M. "Inorganic anion-exchangers for the treatment of radioactive wastes." Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240025.

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10

Shang, Zhaorong. "A study of Ag-110m in aquatic and terrestrial ecosystems and the development of a radioecological model /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23768782.

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11

Fairlie, Ian. "Radioactive waste : international examination of storage and reprocessing of spent fuel." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268029.

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12

Carver, S. J. "Application of geographic information systems to siting radioactive waste disposal facilities." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315467.

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13

Angus, Michael J. "Radioactive waste immobilisation in cement-zeolite and other cement-based matrices." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU362272.

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The ability of zeolites, particularly clinoptilolite, to immobilise Cs arising as an intermediate level radioactive waste is studied. The zeolites are incorporated into Portland cement blends containing additives such as blast furnace slag, pulverised fuel ash and silica fume, and high alumina cement blends. Desorption of Cs+ from the zeolite by ion-exchange cement pore fluid species, mainly K+, Na+ and Ca is studied and ion-exchange isotherms are presented. The Cs distribution between clinoptilolite and cement pore fluid is studied by X-ray diffractometry (XRD) and by chemical analysis of the pore fluid. Some Cs is released into the pore fluid, mainly by ion-exchange with K. The kinetics and mechanism of the pozzolanic reaction between clinoptilolite and Portland cement is studied at various temperatures, using a selective dissolution method, as well as XRD, thermogravimetric analysis and analytical electron microscopy. A model is developed, whereby long-term predictions of clinoptilolite reactivity can be made. Methods of limiting the pozzolanic reaction to ensure the long-term persistence of clinoptilolite in cement by blending are investigated. Slag cements show lowest reactivity. Leach tests are carried out on cement-clinoptilolite cylinders (45x80mm) using a standard leaching method. These confirm the importance of ion-exchange and chemical reactivity in determining leach rate. Additionally, the effect of factors such as clinoptilolite particle size, Cs -loading level, clinoptilolite-cement ratio, quantity and type of cement additive, curing temperature, curing time, leaching temperature and mercury porosity on leach rate are investigated. An optimal cement-clinoptilolite blend is suggested. A method is described for the measurement of oxidation-reduction potential (Eh) of cement pore fluids extracted under pressure, and of measuring the poising capacity of solid and aqueous phases. OPC is mildly oxidising, whereas slag cements provide a reducing environment due to the presence of S-containing species. The implications of E. and pH in terms of radwaste immobilisation are discussed.

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14

Coward, Harriet Michelle. "Health risk assessment of the radioactive emissions from the consolidated incineration facility at Savannah river site." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/17948.

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15

Rostron, Peter D. "Optimised investigation of radioactively contaminated land." Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/47620/.

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Measurements of the radioactive content of environmental samples are potentially very costly, especially when these are made ex situ in a laboratory. A less expensive alternative is to acquire in situ measurements in the field. Both measurement types are subject to uncertainties, some of which arise from different sources depending on the measurement method used. Surveys on radioactively contaminated land found that in situ measurements produced results that were as useful in satisfying the typical objectives of such surveys as ex situ measurements. The random component of analytical uncertainty estimated from duplicated in situ measurements was 2-4 times higher than would have been expected from Poisson statistics, however the sampling uncertainty (0-10 %) was found to be much lower than that for ex situ measurements (44-73 %). This resulted from the combined effects of high heterogeneity of the target radionuclide (137Cs) in the ground, and the comparatively large primary sample mass associated with in situ measurements of gamma-emitting radionuclides. A large sampling mass also means that in situ measurements have an advantage in finding small hotspots of activity, although they may not provide sufficient resolution for spatially mapping lateral distributions of contaminants for remediation purposes. The degree of resolution can be readily changed in the field, however, by the simple expedient of changing the detector height. Experiments with an in situ detector close to the ground surface enabled the position of a small hotspot to be determined to within a few centimetres. To evaluate activity concentrations in the soil, assumptions need to be made about the dimensions of the measured sample, and the distributions of activity within it. This requires some information that might be best obtained from ex situ measurements of excavated samples. However, well planned in situ surveys have the potential to significantly reduce the requirement for these expensive laboratory measurements. A new method of optimising the design of in situ surveys has been developed, based on a generic model for predicting the detector response to small particles of activity at different positions relative to the detector. The new mathematical model used by this method compares well with field measurements, and also with predictions made using a commercially available calibration program.

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16

Tyrer, Mark. "The hydration chemistry of blended Portland blastfurnace slag cements for radioactive waste encapsulation." Thesis, Aston University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315145.

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17

Thomas, Dale D. III. "Radiochemical methods and results used to characterize concentrations of radioactive material in soil at the former McClellan Air Force Base (AFB)." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17613.

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18

Mitchell, Nicholas Grant. "The influence of soil type and climate on the uptake of radionuclides into wheat." Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/8942.

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19

Fairhurst, Andrew Jonathan. "The role of inorganic colloids in the transport of toxic metals through the environment." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/27861.

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Inorganic colloids are considered as potential transporters of toxic metals in the geosphere. If inorganic colloids are stable and able to adsorb toxic metals they may enhance their apparent solubility. If these colloids are mobile in the aquatic environment they may also enhance the transport of toxic metals. It is therefore of considerable interest to determine the characteristics of inorganic colloids in relation to toxic metal transport.

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20

Yoo, Kyung Yeong. "A model for dispersion and deposition of radioisotopes in the planetary boundary layer." Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283242.

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21

Allott, Robert W. "Behaviour of radionuclide contaminated dust in the urban environment of Barrow-in-Furness." Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293166.

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22

Emptage, Matthew Robert. "Radionuclide distribution in relation to sedimentary processes in the Esk estuary, UK." Thesis, Lancaster University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357310.

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23

Palmer, Luiz Rafael. "Hydrological aspects of landfill waste management : a case study of the Drigg low-level radioactive waste repository." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283712.

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24

Price, Rachel Mary. "Interactions of groundwater-borne radionuclides with geological sediments." Thesis, Northumbria University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359522.

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Cobb, John. "Method development for the determination of low-levels of radionuclides in environmental materials." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/12408.

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26

Evans, Ellis Induro. "Environmental characterisation of particle-associated radioactivity deposited close to the Sellafield works." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285387.

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The calculation of dry particle deposition velocity (Vg) for small particles in field studies is subject to much variability between theoretical and measured values. This work will assess some of the factors which may influence the calculation of Vg. The other key parameter which is used to define the near-surface exchange of material is the resuspension factor (K). The certainty of using a Vg which is representative of small particles typically 1 pm requires clarification. During September 1993-1994, four size-selective air and deposition experiments were carried out at an on-site and off-site sampling location close to the BNFL Sellafield nuclear reprocessing plant in Cumbria UK. Dry and total (wet & dry) particle deposition velocities were determined for ^^^Cs, The dry deposition velocities of naturally-occurring ^Be were also determined and used as a 'marker' for small particle transport processes. Resuspension factors K (m ^) for radiocaesium and Plutonium were also derived. Automated individual particle characterisation (AlP) using scanning electron microscopy coupled to energy-dispersive x-ray analysis (SEM-EDXA) was used to determine the particle size distribution and associated elemental composition of material deposited to Frisbee deposition collectors. Enhanced a-emitting hot-spots from surface soils and material deposited to Frisbee collectors at 1 m above ground level were isolated and characterised for size and shape using nuclear track detector film, LR-115. Dry particle deposition velocities for ^^^Cs, 239+240py and were commonly in excess of 1E-03 m s"^ by more than two orders of magnitude. Total deposition velocities (dry and wet) were even higher with values ranging from 0.2 m s^ -1 ms"^ for both radiocaesium and plutonium. High derived values of dry deposition velocity for radiocaesium and plutonium were to some extent influenced by air sampling artefacts. Air sampling artefacts result in an under-estimation of airborne activity for radioactivity associated with particle diameters >10 pm. The derived values of dry particle deposition velocity for ^Be were consistent with literature values of sub-micron sized particles with evidence of a seasonal spring maximum. Resuspension factors K (m'^) for radiocaesium and plutonium agreed well with literature values of weathered weapons fallout values which ranged from 2E-08 to 5E-11 (m"^) for plutonium and radiocaesium respectively. Differences in dry particle deposition velocities for radiocaesium and plutonium between the on-site and off-site locations varied by no more than a factor of three. Correlations between dry particle deposition velocities for Cs and Pu with wind speed, wind direction and precipitation rates were not found. Size-specific air sampling show that the majority of the plutonium was predominantly associated with the >11 lam aerosol size fraction. The association between activity and large particle size suggest this material was probably attached to large soil-derived particles. Plutonium isotope data indicate this material originated fromthe nuclear weapons programme of the late 1950's-earty 1970's. Radiocaesiumactivities were equally distributed between the < 10 ixm and > 11 ^m aerosol fractions for two out of the four runs. This suggests that historically deposited ''^^Cs and current emissions contributed to measured airborne activities. Enhanced a-emitting hot-spots were isolated from bulk surface soils and in material deposited to Frisbee collectors. Rare particles such as these with atypical activities of Pu may lead to mis-leadingly high deposition fluxes. The calculation of Vg in the field is therefore sensitive to the presence of these particles because they are not representative of the aerosol flux and their size s 50 |im precludes their collection by the Pmio air sampler. The main conclusions of this work indicates the very high values of Vg sometimes measured in the field are strongly influenced by large resuspended soil particles and associated air sampling artefacts. The inclusion of large particles within the deposition flux is confirmed by size selective mass based Vg using scanning electron microscopy

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27

McCubbin, David. "Influence of seawater components upon actinide behaviour." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359304.

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28

Low, Robert. "Radon in the groundwater in the chalk of East Anglia." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338249.

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29

Beresford, Nicholas A. "Radiocaesium variability in upland sheep flocks." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273191.

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30

Gulliver, Pauline. "Geochemistry and budgetary considerations of Â¹â´C in the Irish Sea." Thesis, University of Glasgow, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269515.

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31

Usman, James Nathaniel. "Use of inorganic materials for the uptake of anions from simulated nuclear wastes." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293128.

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32

Amini, Siti. "Ion exchange and self diffusion phenomena in zeolite-L and its use for the fixation of #alpha#-emitting radioactive nuclides." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305098.

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33

Khan, Mohammad Saeed. "Differences in the uptake of caesium by plants studied by neutron activation analysis." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357005.

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34

Princewill, Fubara Ferdinand. "Studies on the influence of borate species on the uptake of caesium onto natural zeolites used in nuclear waste treatment." Thesis, University of Salford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261922.

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35

Zamin, M. "Uses of amorphous zirconium phosphate in the treatment and containment of nuclear wastes." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315433.

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36

Al-Hindi, Al-Attar Lina. "Nuclear waste treatment using novel inorganic ion exchange materials." Thesis, University of Salford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272932.

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37

Thompson, Gary S. "Studies of some actinide ions with polyhydroxy carboxylic acids." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385733.

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38

Bonnett, Patrick John Pendrell. "Transport mechanisms and rates for long lived Chernobyl deposits." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316567.

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39

Murdock, Robert Neil. "The transport, behaviour and fate of radionuclides in the freshwater environment." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317144.

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40

Hosseini, Seyed Abbas. "Mechanisms controlling the migration of radionuclides in the environment." Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265441.

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The mechanisms controlling radiocaesium migration through the peat soil were investigated by considering physico-chemical & biological factors affecting radionuclide adsorption/desorption in the peat soil using the Batch & Column Methods as well as a "Direct Fumigation Extraction Method". The biological factors were investigated under different conditions by variation of the micro-organisms content in the peat soil, the soil solution and leaching conditions. Samples of peat soil were reacted with solutions containing caesium ions, and the effect on caesium-K_d determined. The caesium adsorption/desorption was found to be influenced by concentration of caesium and other cations (NH₄⁺, K⁺ and Ca⁺⁺) and by the pH of the solution. Below pH 3, in presence of calcium and potassium, desorption could occur as the exchangeable sites on microparticles were replaced by other cations. At pH>1, in presence of ammonium, adsorption could occur. The distribution coefficient, K_d value was strongly reduced following the addition of NH₄⁺, K⁺ and Ca⁺⁺ at a fixed pH. NH₄⁺ was found to be more effective in the caesium desorption than the other cations. By increasing the concentration of radiocaesium (>0.2 MBq/100μl) the effect became much less leading eventually to an increase in caesium-K_d values. A decrease in the caesium-K_d was also observed at pH<3 in peat samples. It was found that the caesium adsorption approached to an equilibrium state at pH>3 depending upon caesium concentration in peat solution. Caesium adsorption took 180 days to reach equilibrium state. For the measurement of the release/uptake of radionuclides in the peat soils by the microbial biomass, homogenised wet peat samples were fumigated by chloroform. The influence of the microbial population present in the peat on the environmental mobility of caesium was clearly demonstrated.

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41

Goldthorpe, Kathryn. "Stability of cementitious materials in saline environments." Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361798.

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The complexity of cementitious matrices and their application in the immobilisation of radioactive waste has led to detailed examination of their ability to condition permeating water to high pH by both experimental and thermodynamic studies. This thesis considers the stability and solubility of pure hydrate phases: Ca(OH)₂; CaO-SiO₂-H₂O gel, Ca:Si = 0.85, 1.1, 1.4, 1.8; 3CaO.Al₂O₃.6H_zO; 3CaO.Al₂O₃.CaSO₄.12H₂O and 3CaO.Al₂O₃.3CaSO₄.32H₂O, and the phase formation and stability within CaO-SiO₂-CaCO₃-H₂O and CaO-Al₂O₃-SiO₂-H₂O compositions aged in saline solutions, up to 1.5M NaCl and 0.05M MgSo₄, at 25°, 55° and 85°C. The two main high pH conditioning phases of cementitious systems are Ca(OH)₂ and C-S-H gel. Sodium chloride enhances the solubility of Ca(OH)₂ and causes a slight reduction in the Ca:Si ratio of C-S-H gels by the progressive leaching of calcium. Silicate polymerisation within C-S-H phases is inhibited by sodium chloride though it is uncertain how this alters the crystallisation kinetics. The pH buffering capacity is maintained when aged in sodium chloride concentrations 0.5, 1.0 and 1.5M at 25°, 55° and 85°C. The stability of calcium sulfoaluminate aged in sodium chloride is greater than of 3CaO.Al₂O₃.6H₂O, which is unstable with respect to 3CaO.Al₂O₃.CaCl₂.10H₂O in NaCl < 0.5M. These phases undergo a progressive phase change to the 3CaO.Al₂O₃.0.5CaSO₄.0.5CaCl₂.10-12H₂O and 3CaO.Al₂O₃.CaCl₂.10H₂O at increasing aqueous Cl:SO₄ ratios. The formation of a limited solid solution region within 3CaO.Al₂O₃.xCaSO₄.l-xCaCl₂.yH₂O: 0.00 ≤ SO₄:Cl ≤ 0.06, was characterised. In magnesium sulfate, 5 - 50m.mol/l, calcium within hydrate phases is progressively replaced by magnesium with formation of Mg(OH)₂, MgO-SiO₂-H₂O gel, 4MgO.Al₂O₃.xH₂O and gypsum. The pH conditioned by the resultant solid assembly decreases to less than that desirable for containment of radioactive waste, to < 9. Consideration of the phase formation and persistence within the CaO-SiO₂-CaCO₃-H₂O and CaO-Al₂O₃-SiO₂-H₂O systems was examined in solutions containing both sodium chloride and magnesium sulfate. The chemical interactions observed were dominated by the replacement of calcium by magnesium within the solid phases with the formation and persistence of mixtures of Mg(OH)₂, MgO-SiO₂-H₂O gel and gypsum. At low Mg:Ca-CO₃ ratios the persistent stability of gehlenite hydrate at 25°C was observed in appropriate samples. The chemistry of the aqueous phase is dependent on the Mg:Ca-CaCO₃ ratio as well as the Ca:Si ratio. At high Mg:Ca-CaCO₃ ratios the high pH conditioning properties are destroyed and buffering occurs at a value below pH 9.

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42

Bourne, Geoffrey S. "Actinide and fission product activity variations in inter-tidal marine macrophytes." Thesis, Cardiff Metropolitan University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306854.

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43

Walker, Colin S. "Characterisation and solubility behaviour of synthetic calcium silicate hydrates." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288335.

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44

Abbasi, Wasim Ahmed. "Adsorption of uranium from aqueous solution using conventional, modified and solvent-impregnated active carbons." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/33124.

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The use of active carbon (AC) as a potential adsorbent for the removal of uranium from aqueous solution has been investigated. Two principal areas have been studied i.e. uranium adsorption from near-neutral and dilute acidic solutions and uranium adsorption from concentrated acid solutions. The aqueous solution matrix used was nitric acid. In the former case commercial (as-received) and oxidized active carbons were investigated. It was noticed that oxidation of as-received ACs with nitric acid solution significantly improves the adsorption capacity of uranium from both near-neutral and dilute acidic solutions. Oxidized ACs were particularly effective in dilute acidic solution , whilst as-received ACs have shown little uranium sorption. Batch equilibrium isotherms were constructed to compare the adsorption capacities of as-received and oxidized ACs. The batch kinetics of uranium adsorption was studied and a column experiment was performed.

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Bensoussan, Hélène. "Effets d'une contamination à l'uranium sur le système cholinergique : approches in vivo et in vitro." Paris 11, 2009. http://www.theses.fr/2009PA11T073.

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46

Осадча, Е. Н. "Радіоактивне забруднення навколишнього середовища під час видобутку нафти та газу." Thesis, Видавництво СумДУ, 2004. http://essuir.sumdu.edu.ua/handle/123456789/23606.

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47

Suvornmongkhol, Narumon. "Uptake of radionuclides by wheat roots with respect to location of contamination below the surface." Thesis, Online version, 1996. http://ethos.bl.uk/OrderDetails.do?did=2&uin=uk.bl.ethos.321557.

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48

Chang, Ling-Yun. "Development and application of diffusive gradients in thin-films (DGT) for the measurement of stable and radioactive caesium and strontium in surface waters." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264116.

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49

Tung, Sui. "Radon potential mapping in Hong Kong." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B44142420.

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50

Lehmann, Catherine. "Le radon dans les habitations." Bordeaux 2, 1995. http://www.theses.fr/1995BOR2P072.

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