Bibliografie tematiche / Deep disposal of radioactive waste / Tesi
Segui questo link per vedere altri tipi di pubblicazioni sul tema: Deep disposal of radioactive waste.

Tesi sul tema "Deep disposal of radioactive waste"

Autore: Grafiati
Pubblicato: 19 aprile 2025

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili

Scegli il tipo di fonte:

Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Deep disposal of radioactive waste".

Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.

Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.

Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.

1

West, J. M. "Geomicrobiological aspects of the deep disposal of radioactive waste". Thesis, Edinburgh Napier University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379139.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
2

Hoag, Christopher Ian. "Canister design for deep borehole disposal of nuclear waste". Thesis, (5 MB), 2006. http://handle.dtic.mil/100.2/ADA473223.

Testo completo
Abstract (sommario):
Thesis (M.S. in Nuclear Science and Engineering)--Massachusetts Institute of Technology, 2006.
"May 2006." Description based on title screen as viewed on June 1, 2010. DTIC Descriptor(s): Boreholes, Radioactive Wastes, Disposal, Canisters, Thermal Properties, USSR, Diameters, Thickness, Stability, Permeability, Environments, Corrosion, Drilling, Flooding, Storage, Reactor Fuels, Nuclear Energy, Barriers, Emplacement, Internal, Fuels, Igneous Rock, Geothermy, Drills, Hazards, Performance (Engineering), Water, Theses, Granite, Steel, Containment (General). Includes bibliographical references (p. 122-125). Also available in print.
Gli stili APA, Harvard, Vancouver, ISO e altri
3

Hipkins, Emma Victoria. "Comparing the hydrogeological prospectivity of three UK locations for deep radioactive waste disposal". Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33147.

Testo completo
Abstract (sommario):
The UK has a large and growing inventory of higher activity radioactive waste awaiting safe long term disposal. The international consensus is to dispose of this radioactive and toxic waste within a deep geological repository, situated 200-1,000 metres beneath the ground surface. The deep geological disposal facility is designed to be a series of engineered and natural barriers. Groundwater forms an integral component of the natural barrier because it 1) controls the flux of reactive components towards the engineered repository, and 2) forms one of the primary transport mechanism through which released radionuclides can be transported away from the repository. The timescale of protection provided by the natural barrier exceeds those provided by the engineered barriers. Knowledge of the regional hydrogeology is a vital step towards predicting the long term performance of any potential repository site. Topically, a UK government decision in 2017 to re-open a nation-wide repository location search has now created a renewed mandate for site exploration. This research aims to determine the regional groundwater characteristics of three UK settings, selected to be hydrogeologically distinct, in order to determine which, if any, offers natural long term hydrogeological containment potential. The settings selected for analysis include Sellafield in West Cumbria, the Tynwald Basin within the East Irish Sea Basin, and Thetford within East Anglia. Site selection is based on diverse groundwater characteristics, and on previous research suggesting potential hydrogeological suitability at these locations. This research is novel in that it provides, for the first time, a direct comparison between the characteristics and qualities of different regional groundwater settings to contain and isolate radioactive waste, based on UK site specific data. Large and detailed numerical models for the three sites, covering areas of 30 km length by 2- 4 km depth have been developed using the open source finite element code 'OpenGeoSys'. The models couple the physical processes of liquid flow and heat transport, in order to replicate regional scale groundwater flow patterns. Models are calibrated to measured rock properties, and predict groundwater behaviour 10,000 years into the future. Uncertain parameter ranges of lithological and fault permeabilities, and peak repository temperatures are tested to determine the possible range of groundwater outcomes. Geochemical retention is assessed separately and validated using the finite difference modelling software 'GoldSim'. Worst case groundwater characteristics for containment and isolation at each site are compared to an 'ideal' benchmark far-field hydrogeological outflow scenario, and scored accordingly using a newly proposed method of assessment. Results show that the Tynwald Basin offers the best potential of the three sites for natural radionuclide containment, performing between 3.5 and 4 times better than Sellafield, and between 1.7 and 4 times better than Thetford. The Tynwald Basin is characterised by 1) long and deep groundwater pathways, and 2) slow local and regional groundwater movement. Furthermore, the Tynwald Basin is located at a feasible tunnelling distance from the coast, adjacent to the UK's current nuclear stockpile at Sellafield, and thus could provide a simple solution to the current waste legacy problem. Results from the Sellafield model indicate that this location cannot be considered to exhibit beneficial characteristics due to short and predictable groundwater pathways which ascend, from the repository, towards surface aquifers. Finally, Thetford within East Anglia has never been drilled to depth so that sub-surface rock properties of basement, located beneath layered sediments, are based on evidence inferred from around the UK. Uncertainties in rock properties has produced a wide range of groundwater characteristic possibilities, with results indicting prospective performance to range from 0 to 2.4 times better than Sellafield. As such, the hydrogeological suitability to host a potential deep geological repository is promising when modelled with most-likely permeability values, but cannot be accurately determined at present. Consideration of decaying heat from the heat emitting waste packages at the three sites reveal that the natural groundwater flow patterns can be distorted up to as much as 7 km away from the theoretical repository, depending on setting. This thus changes the use of the term 'near-field' for safety assessments, as implying an area within the immediate vicinity of the excavated repository site. The overarching findings from this research are that: 1) some locations have greater long term radionuclide containment and isolation prospectivity than others, due to variable quality far-field geological and hydrogeological characteristics; 2) the effect of radiogenic heat emission on the natural groundwater flow pattern is dependent on the site specific geological and hydrogeological characteristics, and therefore so is the area defined as the 'near-field'; and 3) a simple method of site comparison is possible for regional groundwater system under steadystate conditions. Recommendations are for scoping models of regional groundwater settings to be used as a comparative tool, such as undertaken as part of this research, to differentiate between potential sites at an early stage of the current UK site selection programme.
Gli stili APA, Harvard, Vancouver, ISO e altri
4

Yang, Ting. "Maturation of Clay Seals in Deep Bore Holes for Disposal of Radioactive waste : Theory and Experiments". Doctoral thesis, Luleå tekniska universitet, Geoteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65794.

Testo completo
Abstract (sommario):
KBS-3 and very deep borehole (VDH) concepts are two major types of long-term geologicaldisposal methods for high-level radioactive waste (HLW) isolating from the biosphere. TheKBS-3V concept for isolating the HLW at the depth of 400-500 m, is the officially proposedoption in Sweden and has been the subject of considerable research in the past few decades,while the VDH concept was considered as an option in the 1950s but later became discouragedbecause of insufficient experience in drilling technology. The greatest merit of the VDHconcept is that the almost stagnant groundwater in the deep boreholes prevents the transport ofthe possible release of radionuclides into the rock or up to the ground level. Since variousdisadvantages of the KBS-3V concept were found in previous research, the superiority of VDHconcept attracted the researchers to continue studying it into the late 1980s.The geological repositories of both of KBS-3V and VDH types primarily consist of a naturalbarrier (host rock) and of an engineering barrier (also known as a buffer/backfill barrier).According to the principle of IAEA and national relative research organizations, thebuffer/backfill material should have low permeability and good expandability, as well assuitable physical and sealing properties.The thesis concerns the VDH concept and is focused on the construction and performance ofthose parts of the sealed repository that are not affected by high temperature or gamma radiation.In the lower part of a VDH repository, the clay packages containing HLW will be exposed tohigh temperature (100-150 􀄇 ) in the borehole and to highly saline groundwater. In theinstallation phase of HLW, the groundwater will be pumped out and replaced by medium-softsmectite clay mud in which the HLW packages are installed vertically. During the hydrationand maturation of the clay components, the microstructural reorganization, water transport,migration of clay particles and redistribution of the density of the components take place. Thematuration determines the transient evolution of the clay seals and influences the rheologicaland soil mechanical behavior in the installation phase. The maturation of clay system alsodetermines their ultimate sealing potential of VDH repositories.This study presents the work carried out for investigating the maturation of the buffer-backfillclay in the HLW deep borehole. Initially in the study three types of clays, the Namontmorillonite,magnesium-rich and illite-smectite mixed layer clays, were examined for estimating their performance as the barrier candidate material. This is mainly presented in theliterature review. The experimental study was conducted on montmorillonite GMZ clays andI/S mixed-layer Holmehus clay. The expandability and permeability tests were carried out forinterpretation of the recorded swelling development and assessment of the effect of the salineconditions, with the goal of deriving a relationship between swelling pressure and hydraulicconductivity for different dry densities. The maturation tests of initially fully-saturatedHolmehus clay and partly saturated GMZ clay were performed. During the tests, the shearstrength mobilised by the relative movement of densified mud and migrated dense clay -contained in a perforated central tube - were determined. According to the results of shearstrength tests, the maximum operation time or the number of clay packages to be placed in asingle operation was evaluated, whilst the suitable saturation degree of the dense clay wasdiscussed as well.A model of the maturation of initially water-saturated clay seals based on Darcy’s law wasworked out and the evolution of the clay components in a lab-scale borehole using Holmehusclay were performed and compared with the experimental recordings. Good agreementsbetween the physical behaviors of the theoretical simulations and the measurements wasachieved by which the validity of the model was verified. Using the results, the hydration andsoil migration in the entire maturation process were presented in diagram. The model was alsoused for preliminary evaluation of the maturation products in real boreholes by assuming thesame Holmehus clay as used in the tests. Two constellation of borehole and dense clay withdifferent diameters, 80 cm borehole /60 cm clay and 80cm/50cm, were assumed. The resultsrespecting dry density and hydraulic conductivity of the ultimate maturation products, and thedegree of homogeneous of the buffer and backfill clay system in the assumed boreholes, arepresented and discussed. The options of different mineral types and initial physical propertiesof the candidate buffer clays provide a reference for engineering barrier design of HLW disposalin VDH.
Gli stili APA, Harvard, Vancouver, ISO e altri
5

Bahlouli, Mohamed Haythem. "Modélisation couplée des écoulements liquide-gaz et de l'hydro-mécanique dans un stockage géologique de déchets radioactifs". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2025. http://www.theses.fr/2025TLSEP028.

Testo completo
Abstract (sommario):
Le stockage géologique profond constitue la solution internationale la plus prometteuse pour la gestion des déchets les plus radioactifs et à durée de vie longue sur de très longues échelles de temps. En France, le projet Cigéo vise à stocker les déchets dits de haute activité (HA), principalement issus des combustibles usés des centrales nucléaires après retraitement et les déchets de moyenne activité à vie longue (MA-VL), qui correspondent aux structures métalliques qui entourent le combustible ou aux résidus liés au fonctionnement et à la maintenance des installations nucléaires. La sûreté du stockage est assurée par un système multi-barrières composé de barrières ouvragées et une roche hôte. Grâce à sa très faible conductivité hydraulique, sa faible diffusion moléculaire et sa capacité significative de rétention des radionucléides, l’argilite du Callovo-Oxfordien (COx) est considérée comme la formation géologique potentielle pour la réalisation du projet. Or, après la fermeture et le scellement de l'installation souterraine, une quantité significative de gaz (principalement de l’hydrogène) peut être générée en raison de plusieurs processus tels que la corrosion anaérobie des métaux, la radiolyse de l'eau et les réactions microbiennes. Si le transitoire hydraulique-gaz des installations souterraines a été très étudié au cours des deux dernières décennies, la représentation de certains processus fortement couplés tels que les écoulements diphasiques multi-composants dans des matériaux poreux très faiblement perméables, à des différentes échelles spatiales et l'hydro-mécanique restent potentiellement complexe. La présente étude a été réalisée à l’Unité d’expertise et de modélisation des installations de stockage, à l'Institut de radioprotection et de sûreté nucléaire. L'objectif était d'améliorer la robustesse des modélisations du comportement hydrodynamique des phases liquide-gaz et traiter la problématique des impacts mécaniques des déformations de la roche et des scellements sur le transport de gaz et vice versa. Seules des simulations numériques sont capables de rendre compte de l’ensemble des phénomènes sur les échelles d’espace et de temps à considérer. Pour cela, deux approches ont été suivies. Une étude analytique de l'écoulement monophasique gaz a été effectuée afin d'évaluer la sensibilité des phénomènes d'écoulement du gaz aux divers paramètres physiques, y compris la compressibilité et l'effet Klinkenberg. Parallèlement, des simulations numériques ont été réalisées sur un modèle d'alvéole de déchets HA. Elles ont permis de mettre en évidence l'évolution de la pression du gaz et la désaturation de la roche hôte et des scellements. Ces simulations prennent en compte la présence de l'air dans la phase gaz, afin d’appréhender le poids d'une atmosphère explosive en lien avec l'inflammabilité de l'hydrogène dans l'air. Ces études étaient aussi le terrain pour introduire des améliorations dans le code TOUGH2 et de développer des outils de pre- et de post- processing qui facilitent l'utilisation de ce code et l'analyse des résultats. Concernant le couplage hydromécanique, une revue bibliographique approfondie est réalisée, et a permis d'isoler les problèmes soulevés par le couplage poro-élastique en présence de gaz. Un modèle d'élasticité linéaire avec un couplage HM basé sur la théorie de Biot est ensuite étudié et implémenté dans le logiciel COMSOL Multiphysics en utilisant la méthode des éléments finis. Des simulations numériques de tests hydro-mécaniques drainés ou non-drainés ont été réalisés. Le couplage a permis de capturer l'interaction entre la variation de pression du fluide et les contraintes et déformations dans la roche poreuse. Un des résultats est la mise en évidence de la production fluide
As a safe long-term management of nuclear waste, deep geological disposal was proposed and is the widely accepted approach to deal with high-level radioactive waste. It is currently being under study in several countries. The long-term safety in a deep geological repository (DGR) is ensured through a multi-barrier system provided by engineered barrier and natural barrier systems. In most multi-barrier system concepts in crystalline and clay rock, argillaceous materials (clay rock or bentonite) are envisaged to use for barrier elements. Due to its very low hydraulic conductivity, low molecular diffusion and significant radionuclide retention capacity, COx claystone is considered as a potential geological host formation for an industrial radioactive waste repository in France. The performance of the host rock and engineered barriers in the construction phase and in a long-term perspective (thousands to million of years) is of primary importance for predicting the risk of dissemination of radioactivity. After the deep geological repository is closed and sealed, significant gas quantity can be generated due to several processes such as the anaerobic metal corrosion, water radiolysis and microbial reactions. Predicting gas flow in low-permeable, saturated materials is a challenging but important task in the risk assessment of a deep geological repository. Pressure build-up and gas migration in host rock and engineered barriers constitute a highly coupled hydro-mechanical (HM) process, and may contribute to the development of preferential gas pathways either by gas-induced micro-fracturing or macro-fracturing. In current numerical studies some behaviors still cannot be well represented, in particular, it is challenging to explain the gas migration behavior in the gas injection tests conducted on the clayey rock and barriers materials. Therefore, to better represent the actual physical process of gas flow, several modeling frameworks are proposed in the present thesis: single-phase gas flow (H2), two-phase water-gas multi-component flow (air, H2), and hydro-mechanical coupling (poro-elasticity). Two-phase gas-water flow in the waste cell model at different scales (a single waste cell contains several High Level Waste containers) is used here to quantitatively study transient hydraulic water-gas phenomena, such as gas pressure evolution and clayey rock desaturation. A wide range of scenarios and hypotheses is tested to assess significant differences between different scenarios in controlling gas migration and the transition from single phase water saturated conditions to two-phase and single phase gas. Although efficient in studying gas migration in presence of hydrogen only, the proposed models has presented a major limitation because of the difficulty in assessing gas phase evolution in presence of air. Multiphase flow of water with a gas phase (hydrogen and air) together with consideration of dissolved hydrogen, air and water vapor diffusion, is studied using equation of state EOS7R (water, brine, RN1, RN2, air) of the TOUGH2 family of codes. We have implemented code enhancements and post-processing scripts, which enhanced our capabilities in analyzing and interpreting results. A separate study of single phase gas flow was developed in order to assess analytically the sensitivity of gas flow phenomena to various rock parameters, including for instance the Klinkenberg effect due to gas slippage at low pressure in tight pores. Concerning the hydromechanical coupling, an extensive review was developed, including poroelastic coupling in the presence of gas. A linear poroelastic model based on Biot theory is studied and implemented in the Finite Elements software COMSOL Multiphysics. The coupling allows us to capture the interaction between fluid pressure variation and the stresses and strains in the porous rock (drained and undrained tests)
Gli stili APA, Harvard, Vancouver, ISO e altri
6

Davison, Nigel. "The geochemistry of radioactive waste disposal". Thesis, Aston University, 1987. http://publications.aston.ac.uk/9698/.

Testo completo
Abstract (sommario):
The present study attempted to identify the significant parameters which affect radionuclide migration from a low level radioactive waste disposal site located in a clay deposit. From initial sorption studies on smectite minerals, increased Kd with decreasing initial cation concentration was observed, and three sorption mechanisms were identified. The observation of anion dependent sorption was related to the existence of a mechanism in which an anion-cation pair are bound to the clay surface through the anion. The influence of competing cations, typical of inorganic groundwater constituents, depended on: (1) Ni/Co:Mn+(Mn+ = competing cation) ratio, (2) nature of M^n+, (3) total solution ionic strength. The presence of organic material in groundwater is well documented, but its effect on cation sorption has not been established. An initial qualitative investigation involving addition of simple organic ligands to Ni(Co)-hectorite samples demonstrated the formation of metal complexes in the clay interlayers, although some modified behaviour was observed. Further quantitative examination involving likely groundwater organic constituents and more comprehensive physical investigation confirmed this behaviour and enabled separation of the organic compounds used into two classes, according to their effect on cation sorption; (i) acids, (ii) amine compounds. X-ray photoelectron spectroscopy, scanning electron microscopy and Mossbauer spectroscopy were used to investigate the nature of transition metal ions sorbed onto montmorillonite and hectorite. Evidence strongly favoured the sorption of the hexaaquo cation, although a series of sorption sites of slightly different chemical characteristics were responsible for broadened peak widths observed in XPS and Mossbauer investigations. The surface sensitivity of XPS enabled recognition of the two surface sorption sites proposed in earlier sorption studies. Although thermal treatment of Fe^3+/Fe^2+-hectorite samples left iron atoms bonded to the silicate sheet structure, Mossbauer evidence indicated the presence of both ferric and ferrous iron in all samples.
Gli stili APA, Harvard, Vancouver, ISO e altri
7

Maiden, Benjamin Gaylord. "Geographic implications of public policy : the siting of noxious facilities /". The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487266011225094.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
8

Esnault, Loïc. "Réactivité géomicrobiologique des matériaux et minéraux ferrifères : impact sur la sureté d'un stockage de déchets radioactifs en milieux argileux". Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10139/document.

Testo completo
Abstract (sommario):
Cette thèse s'est attachée à décrire le concept dynamique d'une activité microbiologique viable et durable en conditions de stockage géologique profond et à évaluer son impact sur les propriétés de confinement et les composants du stockage. Ainsi, dans cette étude, un modèle bactérien basé sur la ferriréduction a été choisi pour ses critères de viabilité dans le système et sa capacité à altérer les matériaux dans les conditions du stockage. Les principaux résultats de ce travail de thèse ont permis de démontrer la capacité du milieu à supporter l'activité bactérienne ferriréductrice et les conditions de son développement dans les environnements argileux profonds. Il a été clairement montré la biodisponibilité du Fe(III) structural des matériaux argileux et des oxydes de fer produits lors des processus de corrosion métallique. Dans ce système, la corrosion paraît être un facteur positif pour les activités bactériennes notamment en produisant une source énergétique, l'hydrogène. Les activités bactériennes ferriréductrices peuvent entraîner une reprise de la corrosion métallique via la consommation des oxydes de fer de la couche passivante. La conséquence directe pourrait être une diminution de la durée de vie des enveloppes métalliques de colisage. Dans le cas des matériaux argileux ferrifères, les conséquences d'une telle activité sont telles qu'elles peuvent avoir un impact sur l'ensemble de l'édifice poreux que ce soit en termes de réactivité chimique des matériaux ou de comportement physique de la barrière argileuse. Un des résultats les plus marquants est la cristallisation de nouvelles phases argileuses à des températures très basses, inférieures à 40°C, témoignant de l'influence considérable de l'activité microbienne anaérobie dans les transformations minéralogiques des minéraux argileux. De plus, il faut noter que ces expériences ont permis de visualiser pour la première fois un mécanisme de respiration bactérienne à distance via une extension de la disponibilité d'éléments essentiels, ici le Fe3+. En conclusion, ces résultats ont clairement démontré l'impact du facteur microbiologique sur la réactivité des matériaux argileux et métalliques tout en s'appuyant sur des paramètres de contrôle de l'activité bactérienne. La pertinence de la prise en compte de ces activités microbiologiques dans le cas des évaluations de sûreté d'un stockage est ainsi établie
This thesis sought to describe the dynamic concept of a viable and sustainable microbiological activity under deep geological disposal conditions and to assess its impact on containment properties and storage components. Thus, in this study, a model based on the bacterial ferric reduction was chosen for its sustainability criteria in the system and its ability to alter the materials in storage conditions. The main results of this work demonstrated the capability of the environment to stand the iron-reducing bacterial activity and the conditions of its development in the deep clay environments. The bio-availability of structural Fe (III) in clay minerals and iron oxides produced during the process of metal corrosion was clearly demonstrated. In this system, the corrosion appears to be a positive factor on bacterial activities by producing an energy source, hydrogen. The iron-reducing bacterial activities can lead to a resumption of metallic corrosion through the consumption of iron oxides in the passive film. The direct consequence would be a reduction of the lifetime of metal containers. In the case of ferric clay minerals, the consequences of such an activity are such that they can have an impact on the overall porous structure both in terms of chemical reactivity of the materials or physical behavior of the clayey barrier. One of the most significant results is the crystallization of new clay phases at very low temperatures, below 40°C, highlighting the influence of the anaerobic microbial activity in the mineralogical transformations of clay minerals. Furthermore, these experiments also allowed to visualize, for the first time, a mechanism of bacterial respiration at distance, this increases the field of the availability of essential elements as Fe3+ for bacterial growth in extreme environment. In conclusion, these results clearly showed the impact of the microbiological factor on the reactivity of clay and metal minerals, while relying on control parameters on bacterial activity. The relevance of taking into account these microbiological activities in the case of safety assessments of a repository is then established
Gli stili APA, Harvard, Vancouver, ISO e altri
9

Adkins, Dawn Marie. "A comparison perceived and calculated risk for a low-level radioactive waste disposal facility". Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/19683.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
10

McKeown, Christopher. "A model approach to radioactive waste disposal at Sellafield". Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/2588/.

Testo completo
Abstract (sommario):
Sellafield in West Cumbria is the potential site of a repository for radioactive, Intermediate Level Waste (ILW). The proposed repository lies at 650 m beneath the ground surface to the west of the 1000 m uplands of the Lake District. The fractured Borrowdale Volcanic Group (BVG) host rock is overlain by a sequence of Carboniferous and Permo-Triassic sediments. Fresh, saline and brine groundwaters exist in the subsurface. Upward trending fluid pressure gradients have been measured in the area of the potential repository site. Steady-state, 2-D simulations of fluid flow were undertaken with the OILGEN code. Topographically driven flow dominates the regional hydrogeology. Subsurface fluid flow trended persistently upwards through the potential repository site. The dense brines to the west of the site promoted upward deflection of groundwaters. The groundwater flow rate through the potential repository site was dependent upon the hydraulic conductivity of the BVG. Calibration of the model was achieved by matching simulated subsurface pressures to those measured in-situ. Emergent repository fluids could reach the surface in 15,000 years. The measured BVG hydraulic conductivity is up to 1000 times too high to be simply declared safe. Geochemical simulations, with Geochemist's Workbench?, showed natural BVG groundwaters display redox disequilibrium. The in-situ Eh is most probably +66 mV. Pyrite, absent from rock fractures, would not enforce a reducing -250 mV Eh. Steel barrels and alkaline cement are intended to geochemically retain 2.5x106 kg of uranium. Simulations of repository cement/BVG groundwater interactions produced pH 10 at 80°C but no change in the +66 mV Eh. Steel barrel interactions produced an alkaline fluid with Eh -500 mV. Uranium solubility in the high pH repository near field was as high as 10-2.7 M, regardless of steel interactions. Uranium solubility adjacent to the repository (pseudo near field) was controlled by Eh; ranging from 10-13 M in the presence of steel, to 10-2.7 M with no steel. Uranium retention is controlled only by steel barrel durability. Oxidising, natural BVG groundwater will enhance steel barrel destruction. Distant from repository (far field) uranium solubility was 10-5.4 M if Eh was as measured in-situ. Thermodynamic data variations affect the calculation of uranium solubility; uranium near field solubility can be as high as 10-1.4 M. Uranium solubilities in near-field high pH groundwater could be more than 600 times greater than the 10-5.5 M used by the UK Nirex Ltd. in their safety case simulations.
Gli stili APA, Harvard, Vancouver, ISO e altri
11

Creese, Thomas Chalmers. "Use of metamodels in a probabilistic radiological assessment /". Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
12

Taiyabi, Asif A. "A multi-attribute analysis of nuclear waste disposal alternatives". Master's thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-02022010-020127/.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
13

Bonnett, Timothy Charles. "A systems view of the nuclear waste dilemma". Master's thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-01202010-020205/.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
14

Whang, Jooho. "Migration of radioactive wastes from shallow land burial site under saturated and unsaturated conditions". Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/16925.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
15

Hoffman, Edward Albert. "Neutron transmutation of nuclear waste". Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/16700.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
16

Pascual, Christopher C. "Evaporation measurements from simulated nuclear waste storage tanks". Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/18208.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
17

Sizer, Calvin Gregory. "Minor actinide waste disposal in deep geological boreholes". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41595.

Testo completo
Abstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.
Includes bibliographical references (leaves 63-65).
The purpose of this investigation was to evaluate a waste canister design suitable for the disposal of vitrified minor actinide waste in deep geological boreholes using conventional oil/gas/geothermal drilling technology. The nature of minor actinide waste was considered, paying particular attention to nuclides whose decay energy and half lives were of relative significance to the minor actinide waste as a whole. Thermal Analysis was performed based on a reference borehole design, by Ian C. Hoag. The strategy of the thermal analysis is aimed at finding peak temperatures within the configuration, paying particular attention to the heat transfer under deep geological conditions in the air gap between the canister and the borehole. A first order economic analysis was made to compare the designed canister emplacement costs to that of intact spent fuel. The results of this analysis show that three minor actinide nuclides dominate heat generation after ten years cooling: Cm-244, Am-241, and Am-243 account for 97.5% of minor actinide decay heat. These three nuclides plus Np-237 account for 99% of the minor actinide mass. The thermal analysis was based on an irretrievable canister design, consisting of a 5 meter long synroc waste form, with minor actinides loaded to 1% wt, an outer radius of 15.8 cm and inner annular radius of 8.5 cm. Filling the annulus with a vitrified technetium and iodine waste form was found to be feasible using a multi-stage emplacement process. This process would only be required for three of the fifty boreholes because technetium and iodine have low heat generations after 10 years cooling. The suggested borehole waste form has a maximum centerline temperature of 349C. The costs of drilling boreholes to meet the demand of 100,000MT of PWR waste are estimated to be 3.5% of the current nuclear waste fund, or about $9.6/kg of original spent fuel.
by Calvin Gregory Sizer.
S.B.
Gli stili APA, Harvard, Vancouver, ISO e altri
18

Cusack, Vincent. "The search for an effective international regime for the long-term safety and security of high level radioactive waste: Pangea and beyond". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2005. https://ro.ecu.edu.au/theses/632.

Testo completo
Abstract (sommario):
This thesis is a study of public policy issues relating to multinational geological repositories for high-level radioactive waste disposal (HLW). Nuclear states have attempted for decades to implement effective radioactive waste policies, though with limited success. The safe disposal of HLW has proven particularly troublesome and, thus far, a solution has eluded all states. A review of radioactive waste policy in the UK, the US and Switzerland reveals some of the underlying themes behind community opposition to repository siting and the reasons for a broader global search. The failure to achieve HLW repositories at a national level has led to much research into the technical, social and political obstacles to site selection, and into international collaboration. In 1999 Pangea Resources International (PRI) concentrated its efforts in securing a multinational HLW repository in the Australian outback, with its two main arguments being economic incentives for Australia and safety and security benefits for a broader range of nation states. The 'proposal' failed to gain public or political acceptance. An examination of the Pangea multinational project is undertaken to determine why the proponents were unable to adequately make their case for the shared repository's benefits. The study finds that the arguments presented to Australia were rejected because the public perceived the risks from hosting the repository to be much greater than the associated benefits.
Gli stili APA, Harvard, Vancouver, ISO e altri
19

Chemia, Zurab. "Modeling internal deformation of salt structures targeted for radioactive waste disposal". Doctoral thesis, Uppsala University, Department of Earth Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9279.

Testo completo
Abstract (sommario):

This thesis uses results of systematic numerical models to argue that externally inactive salt structures, which are potential targets for radioactive waste disposal, might be internally active due to the presence of dense layers or blocks within a salt layer.

The three papers that support this thesis use the Gorleben salt diapir (NW Germany), which was targeted as a future final repository for high-grade radioactive waste, as a general guideline.

The first two papers present systematic studies of the parameters that control the development of a salt diapir and how it entrains a dense anhydrite layer. Results from these numerical models show that the entrainment of a dense anhydrite layer within a salt diapir depends on four parameters: sedimentation rate, viscosity of salt, perturbation width and the stratigraphic location of the dense layer. The combined effect of these four parameters, which has a direct impact on the rate of salt supply (volume/area of the salt that is supplied to the diapir with time), shape a diapir and the mode of entrainment. Salt diapirs down-built with sedimentary units of high viscosity can potentially grow with an embedded anhydrite layer and deplete their source layer (salt supply ceases). However, when salt supply decreases dramatically or ceases entirely, the entrained anhydrite layer/segments start to sink within the diapir. In inactive diapirs, sinking of the entrained anhydrite layer is inevitable and strongly depends on the rheology of the salt, which is in direct contact with the anhydrite layer. During the post-depositional stage, if the effective viscosity of salt falls below the threshold value of around 1018-1019 Pa s, the mobility of anhydrite blocks might influence any repository within the diapir. However, the internal deformation of the salt diapir by the descending blocks decreases with increase in effective viscosity of salt.

The results presented in this thesis suggest that it is highly likely that salt structures where dense and viscous layer/blocks are present undergo an internal deformation processes when these dense blocks start sinking within the diapir. Depending on size and orientation of these blocks, deformation pattern is significantly different within the diapir. Furthermore, model results applied to the Gorleben diapir show that the rate of descent of the entrained anhydrite blocks differs on different sides of the diapir. This suggests that if the anhydrite blocks descent within the Gorleben diapir, they initiate an asymmetric internal flow within it.

Gli stili APA, Harvard, Vancouver, ISO e altri
20

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.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
21

Lockhart, Robert. "Molecular biological characterisation of a low level radioactive waste disposal site". Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402321.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
22

VICENTE, ROBERTO. "Gestao de fontes radioativas seladas descartadas". reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11038.

Testo completo
Abstract (sommario):
Made available in DSpace on 2014-10-09T12:47:18Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:10:16Z (GMT). No. of bitstreams: 1 07974.pdf: 7652856 bytes, checksum: f4eff264fe7ae9ae4d05ffaefb1712a3 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Gli stili APA, Harvard, Vancouver, ISO e altri
23

Paukert, Jill G. "Cost effectiveness of schedule compliance in developing a low-level radioactive waste disposal facility in Texas". Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/29375.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
24

Ghosh, Sarba Bijoy. "Factors affecting the mobility of selected radionuclides codisposed with municipal refuse within landfills". Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/20752.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
25

Powers, Brian Michael. "Characterization of the can-in-canister process /". Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004360.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
26

Hoag, Christopher Ian. "Canister design for deep borehole disposal of nuclear waste". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/41269.

Testo completo
Abstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, June 2006.
Includes bibliographical references (p. 122-125).
The objective of this thesis was to design a canister for the disposal of spent nuclear fuel and other high-level waste in deep borehole repositories using currently available and proven oil, gas, and geothermal drilling technology. The canister is suitable for disposal of various waste forms, such as fuel assemblies and vitrified waste. The design addresses real and perceived hazards of transporting and placing high-level waste, in the form of spent reactor fuel, into a deep igneous rock environment with particular emphasis on thermal performance. The proposed boreholes are 3 to 5 km deep, in igneous rock such as granite. The rock must be in a geologically stable area from a volcanic and tectonic standpoint, and it should have low permeability, as shown in recent data taken from a Russian deep borehole. Although deep granite should remain dry, water in flooded boreholes is expected to be reducing, but potentially corrosive to steel. However, the granite and plug are the containment barrier, not the canister itself. The canisters use standard oil drilling casings. The inner diameter is 315.32mm in order to accommodate a PWR assembly with a width of 214mm. At five meters tall, each canister holds one PWR assembly. The canister thickness is 12.19mm, with an outer diameter of 339.7mm. A liner can extend to the bottom of the emplacement zone to aid in retrievability. The liner has an outer diameter of 406.4mm and a thickness of 9.52mm. The standard drill bit used with a liner of this size has an outer diameter of 444.5mm. Sample calculations were performed for a two kilometer deep emplacement zone in a four kilometer deep hole for the conservative case of PWR fuel having a burnup of 60,000 MWd/kg, cooled ten years before emplacement.
(cont.) Tensile and buckling stresses were calculated, and found to be tolerable for a high grade of steel used in the drilling industry. In the thermal analysis, a maximum borehole wall temperature of 2400C is computed from available correlations and used to calculate a maximum canister centerline temperature of 3370C, or 3190C if the hole floods with water. Borehole repository construction costs were calculated to be on the rate of 50 $/kg spent fuel, which is competitive with Yucca Mountain construction costs. Recommendations for future work on the very deep borehole concept are suggested in the areas of thermal analysis, plugging, corrosion of the steel canisters, site selection, and repository economics.
by Christopher Ian Hoag.
S.M.
Gli stili APA, Harvard, Vancouver, ISO e altri
27

Thompson, Philip Blinn. "The spatial and temporal distribution of risks associated with low level radioactive waste disposal". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184415.

Testo completo
Abstract (sommario):
The disposal of waste is a growing environmental, political, and economic problem. Low level radioactive waste (LLW) disposal is no exception. The major purposes of this dissertation are to examine the economic tradeoffs which arise in the process of LLW disposal and to derive a framework within which the impact of these tradeoffs on LLW disposal policy can be analyzed. There are two distinct stages in the disposal of LLW--the transportation of the waste from sources to disposal sites and the disposal of the waste. The levels of costs and risks associated with these two stages depend on the number and location of disposal sites. Having more disposal sites results in lower transportation costs and risks but also in greater disposal costs and risks. The tradeoff between transportation costs and risks can also be viewed as a tradeoff between present and future risks. Therefore, an alteration in the spatial distribution of LLW disposal sites necessarily implies a change in the temporal distribution of risks. These tradeoffs are examined in this work through the use of a transportation model to which probabilistic radiation exposure constraints are added. Future (disposal) risks are discounted. The number and capacities of LLW disposal sites are varied in order to derive a series of system costs and corresponding expected cancers. This provides policymakers with a cost vs. cancers possibility function. The marginal cost of reducing cancers by changing the number and location of disposal sites is calculated. A possible policy application of this information is illustrated by comparing these costs to an assumed value of life derived from experimental evidence found in the literature. A tentative conclusion is reached that the current movement toward a system of regional LLW disposal sites may be economically suboptimal.
Gli stili APA, Harvard, Vancouver, ISO e altri
28

Toprak, Erdem. "Long term response of multi-barrier schemes for underground radioactive waste disposal". Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/586172.

Testo completo
Abstract (sommario):
The main objective of this thesis is to achieve an improved understanding of the thermo-hydro-mechanical processes and material properties that affect how the gaps and canister) behave during and after installation in the repository. The generated models and methodologies developed in this thesis have provided a deeper understanding of the THM processes taking place in a radioactive spent fuel disposal system and offered strategies for design improvement, material choice and optimization. The Thesis focuses on: - Material characterization (laboratory testing and numerical simulations of these tests), - Thermal dimensioning of repository (fixing canister and tunnel spacing, defining a power decay function for canister, adopting thermal boundary conditions), - 2D THM sensitivity analyses (developing a better understanding of the modelled system, several cases have been studied throughout the thesis), -3 D THM modeling (investigating the effect of variable gas pressure on the thermo-hydro-mechanical results). One of the main contributions of the thesis is to combine comprehensive and complex models to perform the calculations of a single deposition scheme: - BBM (Barcelona Basic Model) to represent clay buffer, BExM (Barcelona Expansive Model) to represent pellet-based components, combined with elasticity to represent rock and canister. - Porosity-dependent permeability and water retention curve (macro-porosity dependent in case of pellets using BExM). - Thermal conductivity depending of degree of saturation. - Gap-specific THM modelling under simplifying assumptions but capturing effects like thermal conductivity that may produce an early peak of temperature, or specific retention curve, which produces extreme, drying near the canister and gap closure that affects swelling pressure development. - Full scale 3D THM modelling with elasto-plastic parameters (BBM) is also an important contribution. The laboratory tests conducted for characterization of materials include: water retention curve tests, thermal conductivity tests, infiltration tests, oedometer tests and tortuosity tests. In general, satisfactory agreement between numerical and measured results is achieved. The majority of 2D sensitivity (fracture position, salinity of the inflow water, rock permeability, filling material between buffer and rock, artificial wetting of pellets etc.) cases show a behavior in safety margins in terms of temperature, density and stresses. A simplified 3D geometry has been adopted for THM calculations to check effect of third dimension. 3D calculations also include a sensitivity analysis. It has been shown that the full saturation of system components is delayed slightly when the air mass balance equation is considered, in other words, a variable gas pressure is taken into account. 3D THM simulations of full scale FISST test (a real scale in situ test will be performed in Onkalo research facility) is considered as a future work to validate, optimize and have better understanding the models and parameters used in the thesis.
El objetivo principal de esta tesis es lograr una mejor comprensión de los procesos termo-hidro-mecánicos y las propiedades del materiales que afectan la forma en que se comportan los componentes del sistema de almacenamiento de los residuos nucleares (barrera arcillosa, relleno, pellets, rocas, huecos y contenedor) durante y después de la instalación en el depósito de residuos. Los modelos y metodologías desarrollados en esta tesis han proporcionado una comprensión más profunda de los procesos de THM que tienen lugar en un sistema de almacenamiento de residuos nucleares y ofrecen estrategias para mejorar el diseño, la selección de materiales y la optimización. La tesis se centra en: - Caracterización de los materiales (ensayos de laboratorio y simulaciones numéricas de estos ensayos), - Dimensionamiento del repositorio (fijación del espaciado entre túneles, definición de una función para la potencia de contenedor con el combustible gastado, adopción de condiciones de contorno térmico), - Análisis de sensibilidad 2D THM (desarrollando una mejor comprensión del sistema modelado, se han estudiado varios casos a lo largo de la tesis). -3D modelo THM (que investiga el efecto de la presión de gas variable en los resultados termo-hidromecánicos). Una de las principales contribuciones de la tesis es combinar modelos completos y complejos para realizar los cálculos de un esquema de repositorio único: - BBM (Barcelona Basic Model) para representar el comportamiento de arcilla no saturada, BExM (Barcelona Expansive Model) para representar componentes como pellets, combinado con modelos de elasticidad para representar roca y el contenedor. - Permeabilidad y curva de retención dependientes de la porosidad (macro-porosidad en el caso de pellets que usan BExM). - Conductividad térmica función del grado de saturación. - Un modelo bi-elastico para representar los huecos. El modelo captura efectos como la conductividad térmica que puede producir un pico temprano de temperatura o curva de retención específica, que produce un secado extremo cerca del contenedor y cierre de huecos, lo que afecta el desarrollo de la presión de hinchamiento. - El modelo de 3D THM a escala real con parámetros elasto-plásticos (BBM) es también una contribución importante. Los ensayos laboratorios realizados para la caracterización de materiales incluyen:ensayo de curva de retención, ensayo de conductividad térmica, infiltración, edómetro y el ensayo de tortuosidad. En general, se logra un acuerdo satisfactorio entre los resultados numéricos y medidos. La mayoría de las analisis de sensibilidad (posición de fractura, salinidad del agua, permeabilidad de la roca, materiales distintos de relleno, condiciones iniciales diferentes para los materiales) muestran un comportamiento en márgenes de seguridad en términos de temperatura, densidad y tensiones. Se ha adoptado una geometría 3D simplificada para los cálculos de THM para verificar el efecto de la tercera dimensión. Los cálculos 3D también incluyen un análisis de sensibilidad. Se ha demostrado que la saturación de los componentes del sistema se retrasa ligeramente cuando se considera la ecuación de balance de masa de aire, en otras palabras, se tiene en cuenta una presión de gas variable. Las simulaciones en 3D de THM del ensayo de FISST a escala real (se realizará un ensayo in situ en la instalación de investigación de Onkalo, Finlandia) se considera un trabajo futuro para validar, optimizar y comprender mejor los modelos y parámetros utilizados en la tesis.
Gli stili APA, Harvard, Vancouver, ISO e altri
29

Bassil, Naji Milad. "Cellulose degradation under alkali conditions, representative of cementitious radioactive waste disposal sites". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/cellulose-degradation-under-alkali-conditions-representative-of-cementitious-radioactive-waste-disposal-sites(230809e2-41df-43fe-bfc3-a0a1f36a6f67).html.

Testo completo
Abstract (sommario):
Deep geological disposal in a multibarrier cementitious facility is being developed by a number of countries for the safe, long-term disposal of intermediate-level radioactive wastes. Intermediate-level radioactive waste, which dominates the radioactive waste inventory in the United Kingdom on a volumetric basis, is a heterogeneous wasteform that contains organic materials including cellulosic materials, encased in concrete. Under the alkaline conditions expected in the cementitious geological disposal facility (GDF), these materials will undergo abiotic, chemical hydrolysis, and will produce degradation products including isosaccharinic acid (ISA) or gluconic acid (GA) that can form soluble complexes with radionuclides. Alkaliphilic microorganisms sampled from a hyperalkaline site contaminated with lime-kiln waste, were able to degrade cellulosic material (tissue paper) in Ca(OH)2 saturated microcosms at a starting pH of 12. Enzymatic processes in these microcosms caused the production of acetate, acidification of the microcosms and a cessation of ISA production. Enrichment cultures prepared at pH 10 and inoculated with a sediment from the same hyperalkaline site were able to degrade ISA, and couple this degradation process to the reduction of electron acceptors that will dominate as the GDF progresses from an aerobic ‘open phase’ through nitrate- and Fe(III)-reducing conditions post closure. A strictly alkaliphilic bacterium belonging to the Bacillus genus was isolated from the nitrate-reducing enrichment culture, and was found to degrade a variety of organic molecules that are expected to be found in a cementitious GDF. Detailed investigation into the growth of this bacterium suggested that different mechanisms are involved in the biodegradation of ISA and GA, and that bacterial growth is coupled to a decrease in soluble U(VI) concentrations. This implies that microorganisms could have a role in attenuating the mobility of radionuclides in and around a GDF via (i) the biodegradation of cellulose and cessation of ISA production, (ii) the biodegradation of the ligands (ISA and GA) and (iii) the immobilisation of radionuclides. This should facilitate the reduction of undue pessimism in the long-term performance assessment of suchfacilities.
Gli stili APA, Harvard, Vancouver, ISO e altri
30

Smith, Kurt. "Radionuclide behaviour in hyperalkaline systems relevant to geological disposal of radioactive waste". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/radionuclide-behaviour-in-hyperalkaline-systems-relevant-to-geological-disposal-of-radioactive-waste(0b04ab1b-4392-4cd3-81d7-c2ba02fd782d).html.

Testo completo
Abstract (sommario):
In many countries the current plan for the management of intermediate and high level radioactive wastes is to dispose of the radioactive materials underground in a Geological Disposal Facility (GDF) to prevent release of radioactivity to the environment. In the UK, the repository for intermediate level waste may be backfilled with cementitious material and it is clear that grout and cement will be used during many disposal concepts. Upon saturation, the cement will react creating a region of hyperalkaline geochemical conditions extending away from the GDF, within which, significant changes in radionuclide behaviour are expected. Therefore, this thesis utilises a range of experimental and analytical techniques to try to gain a mechanistic understanding of the behaviour of some key radionuclides (U(VI), Np(V) and Eu(III) as an analogue for Cm(III)/Am(III)) in a range of high pH systems of direct relevance to any cementitious GDF. U(VI) interaction with calcite (calcium carbonate, a common component in high pH cements and the natural environment) surfaces was studied in the 'old' (Ca(OH)2 solution; pH 10.5) and 'young' (Na+, K+, Ca2+; pH 13.3) leachates. In the 'old' leachate, luminescence spectroscopy, batch experiments and kinetic modelling suggested that at low concentrations (smaller or equal to 0.42 µM) a Ca2UO2(CO3)3-like surface complex formed. At higher concentrations, batch experiments, extended X-ray absorption fine structure spectroscopy and luminescence suggested that a surface mediated precipitation mechanism was controlling U(VI) concentrations. Further TEM analysis confirmed that a calcium uranate (CaUO4) solid phase was forming on the calcite surfaces. In the 'young' leachate, batch experiments showed that U(VI) had little affinity for the calcite surface, with no statistically relevant removal from solution observed over a 18 month period. Small angle X-ray diffraction data demonstrated that the U(VI) was probably present in the form of U(VI) intrinsic colloids. Np(V) solubility and sorption to calcite under hyperalkaline conditions were studied using batch, X-ray absorption spectroscopy, and geochemical modelling techniques. It was determined that Np(V) solubility in 'old' cement leachates was consistent with the literature. However, in 'young' cement leachates, an unidentified calcium containing phase was controlling solubility. It was demonstrated that sorption to calcite in 'old' leachates was controlled by the formation of a >CO3NpO2 surface complex, whereas, in the 'young' leachates interaction with the calcite surface was controlled by a precipitation mechanism. Eu(III) sorption to a potential GDF backfill material, Nirex Reference Vault Backfill (NRVB) cement, was studied. The kinetics of removal were rapid with 98.5% Eu(III) removal within 24 hours. Ultrafiltration experiments indicated that all Eu(III) remaining in solution was associated with NRVB derived colloids. Additional experiments using ethylenediaminetetraacetic acid (EDTA) as a competing ligand show that removal from solution was significantly reduced at high concentrations (>0.01 M). These EDTA experiments also indicated some irreversibility in the systems, possibly caused by incorporation into the C-S-H or calcite structures.
Gli stili APA, Harvard, Vancouver, ISO e altri
31

Richter, Jennifer. "New Mexico's nuclear enchantment| Local politics, national imperatives, and radioactive waste disposal". Thesis, The University of New Mexico, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3601288.

Testo completo
Abstract (sommario):

The use of nuclear technologies has left an indelible mark on American society. The environmental, political, economic, and social costs of creating, producing, and utilizing technologies such as nuclear weapons and nuclear energy have left a legacy of radioactive waste. To date, there is no comprehensive path for disposing of the different kinds of waste produced by the nuclear industry, including spent nuclear fuel that is now held on site at nuclear power plants. The question of how to deal with nuclear waste has plagued the nuclear industry, governmental agencies, and the concerned public for most of the nuclear era.

There is one permanent geologic repository in the U.S., called the Waste Isolation Pilot Plant (WIPP), located in the salt beds outside of Carlsbad, New Mexico. Presently, WIPP is only allowed to hold low-level transuranic waste produced by military installations during the Cold War. This project looks at the ways that federal attention has turned to this remote site in the Chihuahuan Desert as a potential solution for storing high-level nuclear waste as well. Using ethnographies, archival research, and the ideas expressed at numerous public meeting held in the region, this project shows how nuclear communities are framed in discourses surrounding nuclear waste through the concept of nuclearism, which posits that nuclear technologies are wholly beneficial to society. Specifically, this project examines how concepts involving the immutability of nature and science interact to form problematic assumptions regarding the behavior of the environment in relation to nuclear waste. Furthermore, conversations that focus solely on the production of "sound science" ignore the political and social consequences of creating and moving nuclear waste across the country, ensnaring more communities into the web of potential nuclear consequences. Nuclear issues also intersect different scales, troubling the idea of local consent, the idea of a homogenous public, and whether nuclear technologies can be tools of democracy. The events at the Fukushima nuclear power plant on March 11, 2011 underscored the delicate balance of technology and nature, and showed the inherent vulnerabilities of complex technological systems. By connecting the complex natures of the desert, salt, radiation, and time together with questions of political representation, this project looks at how the nuclear future is being shaped in the desert of New Mexico.

Gli stili APA, Harvard, Vancouver, ISO e altri
32

Mackay, R. "Synthetic hydrogeological modelling to explore data worth in radioactive waste disposal assessments". Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261954.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
33

Duncan, Ian J. "Radioactive waste : risk, reward, space and time dynamics". Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365656.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
34

Petelka, Martin Frank. "Leaching of radioactive waste forms under saturated and unsaturated flow conditions". Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/18224.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
35

Chiu, Yu-yeung. "Environmental radiation monitoring at the low level radioactive waste storage facility in Siu A Chau and development of a particle dispersion model in marine environment". Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38573611.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
36

Stone, Michael. "An assessment of the modular high temperature gas-cooled reactor for actinide burning". Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/13369.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
37

Stover, Shannon L. "Removal of uranium from aqueous wastes using electrically charged carbon nanofibers". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1769.

Testo completo
Abstract (sommario):
Thesis (M.S.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains ix, 85 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 71-74).
Gli stili APA, Harvard, Vancouver, ISO e altri
38

Kuo, Weng-Sheng. "Evaluation of deep drillholes for high level nuclear waste disposal". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/45197.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
39

Iida, Yoshihisa. "Study on Migration Behavior of Selenium for Safety Assessment of Radioactive Waste Disposal". 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157575.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
40

Sun, J. "Carbonation kinetics of cementitious materials used in the geological disposal of radioactive waste". Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1306875/.

Testo completo
Abstract (sommario):
The use of cement based materials could be widespread in the long term management of radioactive materials in the United Kingdom. In the Geological Disposal Concepts proposed by the Radioactive Waste Management Directorate of the Nuclear Decommissioning Authority (NDA), several cement based materials are used in the long-term management of intermediate-level wastes. Much of the waste will be immobilised within stainless steel containers using cement grouts based on ordinary Portland cement (OPC) blended with blast furnace slag (BFS) or pulverised fuel ash (PFA). The resulting waste packages will be placed underground in a Geological Disposal Facility (or Repository) after a period of storage at the waste producers’ sites. The repository will then be filled with cement based backfill. The encapsulation grouts and the backfill materials will perform as both a physical barrier and chemical barrier for confining the radioactive wastes. During storage and disposal, some wastes may generate carbon dioxide from the degradation of organic materials and this will react with the cement based materials. Therefore, carbonation of the cementitious encapsulation grouts and backfill materials is of interest because of the resulting changes to their physical and chemical properties and also because of its ability to remove carbon-14 labelled carbon dioxide from the gas phase. It is also important to understand the reaction kinetics under a range of conditions, due to the long-term nature of storage and disposal. In this work, the carbonation progress of one backfill material and of two encapsulation grouts used in the UK has been studied in batch reactors. These materials are known as Nirex Reference Vault Backfill (NRVB), 3:1 PFA/OPC and 3:1 BFS/OPC. Based on the single dimensional carbonation experiments, fundamental parameters affecting the rate of carbonation were investigated and the carbon dioxide uptake capacity of each material was determined. For these three materials, an increase in relative humidity (75% to 100%) decreases the carbonation rate. A higher reaction pressure can facilitate the carbonation, but its effect was less obvious than the effect of relative humidity. The progression of the carbonation fronts have also been observed by various techniques and the shape of carbonation front was proved to be influenced by the relative humidity. Special attention was given to the modelling of the kinetics and mechanism of the carbonation reaction of these materials. This work provides fundamental understanding of the carbonation reaction of NRVB, 3:1 PFA/OPC and 3:1 BFS/OPC of relevance to the future optimization of a geological disposal facility in the UK and to assessments of the performance of such a facility.
Gli stili APA, Harvard, Vancouver, ISO e altri
41

Berkhout, F. "Radioactive waste : Institutional determinants of management and disposal policy in three European countries". Thesis, University of Sussex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234039.

Testo completo
Abstract (sommario):
The objective of this thesis has been to write a detailed historical account of the policy and practice of radioactive waste management in Britain. Sweden and West Germany, and to draw out implications for theory and public policy. The research was motivated by the perception that many of the technical and socio-political problems of dealing with radioactive wastes had not been resolved. and that these had a critical bearing on the political viability of civil nuclear programmes. By comparing the evolution of the policy process in three countries it has been possible to develop a better understanding of the particular operational. regulatory and political factors determining policy in each case. In addition. fundamental issues in the regulation of radwastes - the setting of standards and criteria for management and disposal, the institutional structure for oversight and policy-making, research policy and its relation to storage. treatment. disposal and siting policy. and the validation of disposal techniques according to performance goals amid great long-term uncertainty - have been clarified through their analysis in a comparative framework. The main conclusions are three-fold. First. the presence or absence of commitments to the reprocessing of spent fuel for a wide range of strategic, industrial and legal reasons have been critical to the success in finding an acceptable radwaste management and disposal policy (or strategy). Politically it is not possible to make a clear distinction between radwaste management and policy for the rest of the back-end of the nuclear fuel cycle. Analytically It is also not possible to separate the two. Second, because of this complex but intimate relationship to reprocessing policy, the dynamism and consistency of radwaste policies are highly dependent on the industrial and political contexts of the drive to reprocessing. Traditionally a view on reprocessing has been virtually synonomous with a faith or scepticism in the future of nuclear power. Experience in the three countries covered in this research shows that there may be a basic conflict between integrated and viable radwaste policies and strong nuclear policies. In this sense radioactive waste could turn out to be the achilles heel of the nuclear industry. Third, the policy process, and indeed its goals, was rather unique to national circumstances (the legal and institutional framework, industrial and political structures). This demonstrates one of the principle arguments of the thesis which is that the innovation process for radwaste management and disposal technologies cannot be seen merely as a technical process, but has to be seen as a process of political and institutional negotiations. There are no perfect' solutions'. Questions of procedure and the context of policy have to be considered as central to the innovation process. Generalizing the patterns which emerge is however difficult, and conclusions must be applied with care under conditions of continuing change and uncertainty.
Gli stili APA, Harvard, Vancouver, ISO e altri
42

Moyce, Elizabeth Bernice Annwen. "Rock alteration at high pH relevant to the geological disposal of radioactive waste". Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/8914/.

Testo completo
Abstract (sommario):
Dissolution of the cement used in radioactive waste repositories will produce a high pH leachate (pH 10.5-13.1) that will evolve in pH and composition over time, remaining hyperalkaline for 106 years. This will migrate into the repository host rock potentially altering the rock’s physical and chemical properties, and its function as a barrier to radionuclide migration. To investigate the possible alteration over timescales relevant for geological disposal (104 to 105 years), previous studies included short term (< 2 years) laboratory experiments, natural analogue studies (100s to 105 years) and predictive modelling. However, the geochemical and mineralogical processes which may occur as such systems evolve remain poorly constrained. Here, rock alteration in high pH solutions, analogous to cement leachates, has been investigated on short (1 year), medium (15 years) and long (100s years) timescales. The short term investigation agreed with previous studies finding that silicate mineral dissolution and C-S-H precipitation were the predominant alteration processes. In the medium term study, although initially silicate mineral dissolution and C-S-H precipitation occurred, by 15 years of reaction neo-formed Mg-silicates replaced the C-S-H. To investigate rock alteration on a longer timescale Herbert’s Quarry, where high pH fluids have existed for 100s years, was characterised and assessed as a potential analogue site. However, the site was found to have limited applicability in the context of the high pH rock alteration expected at a radioactive waste repository. The impact of rock alteration on U(VI) behaviour was also investigated in the short and medium term. In the short term, U(VI) behaviour during rock alteration varied between solutions representative of different periods of cement leachate evolution, with potential impacts for radionuclide transport. The sorption of U(VI) to unaltered rock and rock altered for 15 years was also investigated. This suggested alteration may increase a rock’s sorption capacity for U(VI).
Gli stili APA, Harvard, Vancouver, ISO e altri
43

Takamura, Hisashi. "A study on wireless transmission monitoring of geological disposal repository for radioactive waste". 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136340.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
44

Mohammad, Javeed. "Optimization of high-level waste loading in a borosilicate glass matrix by using chemical durability modeling approach". Master's thesis, Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-10282002-160552.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
45

Martin, R. Scott. "Chemchar gasification of radioactive, inorganic, and organic laden wastes /". free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9946277.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
46

Cassels, Brad M. "The determination of three selected sites for the construction and operation of a low level radioactive waste storage and burial facility". Thesis, Queensland University of Technology, 2000. https://eprints.qut.edu.au/37051/1/37051_Digitised%20Thesis_AuthorSupplied.pdf.

Testo completo
Abstract (sommario):
Radioactive wastes are by-products of the use of radiation technologies. As with many technologies, the wastes are required to be disposed of in a safe manner so as to minimise risk to human health. This study examines the requirements for a hypothetical repository and develops techniques for decision making to permit the establishment of a shallow ground burial facility to receive an inventory of low-level radioactive wastes. Australia’s overall inventory is used as an example. Essential and desirable siting criteria are developed and applied to Australia's Northern Territory resulting in the selection of three candidate sites for laboratory investigations into soil behaviour. The essential quantifiable factors which govern radionuclide migration and ultimately influence radiation doses following facility closure are reviewed. Simplified batch and column procedures were developed to enable laboratory determination of distribution and retardation coefficient values for use in one-dimensional advection-dispersion transport equations. Batch and column experiments were conducted with Australian soils sampled from the three identified candidate sites using a radionuclide representative of the current national low-level radioactive waste inventory. The experimental results are discussed and site soil performance compared. The experimental results are subsequently used to compare the relative radiation health risks between each of the three sites investigated. A recommendation is made as to the preferred site to construct an engineered near-surface burial facility to receive the Australian low-level radioactive waste inventory.
Gli stili APA, Harvard, Vancouver, ISO e altri
47

FERREIRA, ROBSON de J. "Desenvolvimento de metodologia para a caracterizacao de fontes radioativas seladas". reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9570.

Testo completo
Abstract (sommario):
Made available in DSpace on 2014-10-09T12:28:09Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:01:44Z (GMT). No. of bitstreams: 0
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Gli stili APA, Harvard, Vancouver, ISO e altri
48

Bates, Ethan Allen. "Optimization of deep boreholes for disposal of high-level nuclear waste". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97968.

Testo completo
Abstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 223-240).
This work advances the concept of deep borehole disposal (DBD), where spent nuclear fuel (SNF) is isolated at depths of several km in basement rock. Improvements to the engineered components of the DBD concept (e.g., plug, canister, and fill materials) are presented. Reference site parameters and models for radionuclide transport, dose, and cost are developed and coupled to optimize DBD design. A conservative and analytical representation of thermal expansion flow gives vertical velocities of fluids vs. time (and the results are compared against numerical models). When fluid breakthrough occurs rapidly, the chemical transport model is necessary to calculate radionuclide concentrations along the flow path to the surface. The model derived here incorporates conservative assumptions, including instantaneous dissolution of the SNF, high solubility, low sorption, no aquifer or isotopic dilution, and a host rock matrix that is saturated (at a steady state profile) for each radionuclide. For radionuclides that do not decay rapidly, sorb, or reach solubility limitations (e.g., 1-129), molecular diffusion in the host rock (transverse to the flow path) is the primary loss mechanism. The first design basis failure mode (DB 1) assumes the primary flow path is a 1.2 m diameter region with 100x higher permeability than the surrounding rock, while DB2 assumes a 0.1 mm diameter fracture. For the limiting design basis (DB 1), borehole repository design is constrained (via dose limits) by the areal loading of SNF (MTHM/km2 ), which increases linearly with disposal depth. In the final portion of the thesis, total costs (including drilling, site characterization, and emplacement) are minimized ($/kgHM) while borehole depth, disposal zone length, and borehole spacing are varied subject to the performance (maximum dose) constraint. Accounting for a large uncertainty in costs, the optimal design generally lies at the minimum specified disposal depth (assumed to be 1200 in), with disposal zone length of 800-1500 m and borehole spacing of 250-360 meters. Optimized costs range between $45 to $191/kgHM, largely depending on the assumed emplacement method and drilling cost. The best estimate (currently achievable), minimum cost is $134/kgHM, which corresponds to a disposal zone length of -900 meters and borehole spacing of 272 meters.
by Ethan Allen Bates.
Ph. D.
Gli stili APA, Harvard, Vancouver, ISO e altri
49

Shaikh, Samina. "Effective thermal conductivity measurements relevant to deep borehole nuclear waste disposal". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41301.

Testo completo
Abstract (sommario):
Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.
Includes bibliographical references (leaves 106-107).
The objective of this work was to measure the effective thermal conductivity of a number of materials (particle beds, and fluids) proposed for use in and around canisters for disposal of high level nuclear waste in deep boreholes. This information is required to insure that waste temperatures will not exceed tolerable limits. Such experimental verification is essential because analytical models and empirical correlations can not accurately predict effective thermal conductivities for complex configurations of poorly characterized media, such as beds of irregular particles of mixed sizes. The experimental apparatus consisted of a 2.54 cm. diameter cylindrical heater (heated length = 0.5 m) , surrounded by a 5.0 cm inner diameter steel tube. Six pairs of thermocouples were located axially on the inside of the heater sheath, and in grooves on the air-fan-cooled outer tube. Test media were used to fill the annular gap, and the temperature drop across the gap measured at several power levels covering the range of heat fluxes expected on a waste canister soon after emplacement. Values of effective thermal conductivity were measured for air, water; particle beds of sand, SiC, graphite and aluminum; and an air gap subdivided by a thin metal sleeve insert. Results are compared to literature values and analytical models for conduction, convection and radiation. Agreement within a factor of 2 was common, and the results confirm the adequacy, and reduce the uncertainty of prior borehole system design calculations. All particle bed data fell between 0.3 and 0.5 W/moC, hence other attributes can determine usage.
by Samina Shaikh.
S.M.and S.B.
Gli stili APA, Harvard, Vancouver, ISO e altri
50

Green, Ronald T. "Radionuclide transport as vapor through unsaturated fractured rock". Diss., The University of Arizona, 1986. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1986_348_sip1_w.pdf&type=application/pdf.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Ti possono interessare anche gli elenchi di altri tipi di fonti sul tema "Deep disposal of radioactive waste":
Articoli di riviste Libri
Offriamo sconti su tutti i piani premium per gli autori le cui opere sono incluse in raccolte letterarie tematiche. Contattaci per ottenere un codice promozionale unico!

Vai alla bibliografia