En centrales nucléaires, un accident grave est une séquence très peu probable d’événements durant laquelle des composants du réacteur sont significativement endommagés, par interactions chimiques et/ou fusion, à cause de très hautes températures. Cela peut mener à des rejets radiotoxiques dans l’enceinte et à une entrée d’air dans le réacteur. Dans ce contexte, ce travail de thèse mené chez EDF R&D visait à modéliser la détérioration du gainage combustible, en alliages de zirconium, en conditions accidentelles : haute température et soit vapeur soit mélange air-vapeur. L’objectif final était d’améliorer la simulation par le code MAAP de l’oxydation du gainage et de la production d’hydrogène, en particulier pendant un renoyage avec de l’eau. Dû à l’épaississement progressif d’une couche de ZrO2 dense et protectrice, la cinétique d’oxydation du Zr en vapeur à hautes températures est généralement (sous-)parabolique. Cependant, à certaines températures, cette couche d’oxyde peut se fissurer, devenant poreuse et non protectrice. Par ce processus de « breakaway », la cinétique d’oxydation devient plus linéaire. De plus, l’augmentation de température peut mener les matériaux du réacteur à fondre et à se relocaliser dans le fond de cuve dont la rupture peut induire une entrée d’air dans le réacteur. Dans ce cas, l’oxygène et l’azote réagissent avec les gaines pré-oxydées, successivement par oxydation du Zr (épaississant la couche de ZrO2), nitruration du Zr (formant des particules de ZrN) et oxydation du ZrN (créant de l’oxyde et relâchant de l’azote). Ces réactions auto-entretenues relancent la fissuration du gainage et de sa couche de ZrO2, induisant une hausse de sa porosité ouverte. Afin de quantifier cette porosité du gainage, un protocole expérimental innovant en deux étapes a été défini et appliqué : il consistait à soumettre des échantillons de gainage en ZIRLO® à diverses conditions accidentelles pendant plusieurs durées puis à des mesures de la porosité ouverte par porosimétrie par intrusion de mercure. Les conditions de corrosion comprenaient plusieurs températures allant de 1100 à 1500 K ainsi que de la vapeur et un mélange air-vapeur 50-50 mol%. Pour les échantillons de ZIRLO® oxydés en vapeur, sauf à 1200 et 1250 K, les transitions de cinétique n’ont pas lieu et la porosité ouverte reste négligeable au cours de l’oxydation. Cependant, pour les autres échantillons, corrodés en air-vapeur ou oxydés en vapeur à 1200 ou 1250 K, des transitions « breakaway » sont observées et les résultats de porosimétrie montrent que la porosité ouverte augmente au cours de la corrosion, proportionnellement au gain en masse. De plus, il a été mis en évidence que la distribution de tailles de pores des échantillons de ZIRLO® s’étend significativement pendant la corrosion, en particulier après « breakaway ». En effet, ces tailles vont de 60 μm à environ : 2 μm avant la transition, 50 nm juste après et 2 nm plus longtemps après. Enfin, un modèle numérique en deux étapes a été développé dans le code MAAP pour améliorer sa simulation de l’oxydation du gainage. D’abord, grâce à la proportionnalité entre porosité ouverte et gain en masse des échantillons, des corrélations de porosité ont été implémentées pour chaque condition de corrosion. Ensuite, les valeurs de porosité calculées sont utilisées pour augmenter proportionnellement la vitesse d’oxydation du gainage. Ce modèle amélioré simule ainsi non seulement les réactions chimiques des gaines en Zr (oxydation et nitruration) mais aussi leur dégradation mécanique et son impact sur leur vitesse d’oxydation. Ceci a été validé en simulant des essais QUENCH (-06, -08, -10 et -16), conduits au KIT pour étudier le comportement de gaines dans des conditions accidentelles avec un renoyage final. Ces simulations montrent un meilleur comportement thermique du gainage et une production d’hydrogène significativement plus haute et donc plus proche des valeurs expérimentales, en particulier pendant le renoyage. / In nuclear power plants, a severe accident is a very unlikely sequence of events during which components of the reactor core get significantly damaged, through chemical interactions and/or melting, because of very high temperatures. This may potentially lead to radiotoxic releases in the containment building and to air ingress in the reactor core. In that context, this thesis work led at EDF R&D aimed at modeling the deterioration of the nuclear fuel cladding, made of zirconium alloys, in accidental conditions: high temperature and either pure steam or air-steam mixture. The final objective was to improve the simulation by the MAAP code of the cladding oxidation and of the hydrogen production, in particular during a core reflooding with water. Due to the progressive thickening of a dense and protective ZrO2 layer, the oxidation kinetics of Zr in steam at high temperatures is generally (sub-)parabolic. However, at certain temperatures, this oxide layer may crack, becoming porous and not protective anymore. By this “breakaway” process, the oxidation kinetics becomes rather linear. Additionally, the temperature increase can lead core materials to melt and to relocate down to the vessel lower head whose failure may induce air ingress into the reactor core. In this event, oxygen and nitrogen both react with the pre-oxidized claddings, successively through oxidation of Zr (thickening the ZrO2 layer), nitriding of Zr (forming ZrN particles) and oxidation of ZrN (creating oxide and releasing nitrogen). These self-sustained reactions enhance the cracking of the cladding and of its ZrO2 layer, inducing a rise of its open porosity.In order to quantify this cladding porosity, an innovative two-step experimental protocol was defined and applied: it consisted in submitting ZIRLO® cladding samples first to various accidental conditions during several time periods and then to measurements of the open porosity through porosimetry by mercury intrusion. The tested corrosion conditions included numerous temperatures ranging from 1100 up to 1500 K as well as both pure steam and a 50-50 mol% air-steam mixture. For the ZIRLO® samples oxidized in pure steam, except at 1200 and 1250 K, the “breakaway” kinetic transitions do not occur and the open porosity remains negligible along the oxidation process. However, for all other samples, corroded in air-steam or oxidized in pure steam at 1200 or 1250 K, “breakaway” transitions are observed and the porosimetry results show that the open porosity increases along the corrosion process, proportionally to the mass gain. Moreover, it was evidenced that the pore size distribution of ZIRLO® samples significantly extends during corrosion, especially after “breakaway” transitions. Indeed, the detected pore sizes ranged from 60 μm down to around: 2 μm before the transition, 50 nm just after and 2 nm longer after. Finally, a two-step numerical model was developed in the MAAP code to improve its simulation of the cladding oxidation. First, thanks to the proportionality between open porosity and mass gain of cladding samples, porosity correlations were implemented for each tested corrosion condition. Second, the calculated porosity values are used to proportionally enhance the cladding oxidation rate. This improved model thus simulates not only chemical reactions of Zr-based claddings (oxidation and nitriding) but also their mechanical degradation and its impact on their oxidation rate. It was validated by simulating QUENCH tests (-06, -08, -10 and -16), conducted at KIT to study the behavior of claddings in accidental conditions with a final reflooding. These simulations show a better cladding thermal behavior and a hydrogen production significantly higher and so closer to experimental values, in particular during the reflooding.

Die Arbeit beschäftigt sich mit einem besonders aus dem mittleren Donauraum bekannten frühmittelalterlichen bis neuzeitlichen Bestattungsbrauch, bei dem Sicheln als Grabbeigaben verwendet worden sind. Dafür wurden exemplarisch alle publizierten Gräber mit Sicheln aus der Slowakei untersucht und Zusammenhänge mit dem Sozialstatus der Bestatteten herausgearbeitet sowie allmähliche Veränderungen dieser Beigabensitte seit dem hohen Mittelalter festgestellt. / This work is dealing with a burial rite using sickles as grave goods, which occured particularly in the middle Danube region from early medieval up to early modern times. A systematic analysis including all published graves containing sickles from the area of today Slovakia led to an interesting relation to the social status of the buried persons and further results concerning chronological changes of this phenomena. / Práca sa zaoberá s kosákmi ako časť hrobového inventáru v stredoveku (Obr. 8). Doterajšie bádania navrhovali rozdielne interpretácie tohto pohrebného zvyku. Kosák v hroboch bol vysvetlovaný ako zbraň, prípadne súčasť bojovníkov alebo jazdcov (Obr. 6), ako osobné pracovné náradie mŕtveho alebo ako predmet s ochrannou-magickou funkciou. Systematické vyhodnotenie všetkých hrobov, v ktorých sa našli kosáky na území celého Slovenska vynášalo d’alšie výsledky čo sa týka tejto problematiky. Základ analýzy tvorilo 87 hrobov s kosákmi z 37 nálezisk (Obr. 1 a 2). Medzi tými sa nachádzalo aj 8 novovekých hrobov z 16.-18. stor., ktoré kvôli nedostatočným údajom zohrali len podradnú úlohu. Hroby, v ktorých sa nachádzal kosák boli rozčlenené do 5 časových skupín, aby bolo možné sledovať chronologické vývoje (Obr. 3). Vyhodnotenie ukazovalo, že mŕtvi pochovaní s kosákmi, boli často vystrojovaní s mnohými d’alšími predmetmi (Obr.7). Približne jedna tretina sa ešte vyznamenala nezvyčajne početnými a cennými predmetmi pohrebného inventára a nákladnou úpravou hrobovej jamy s neobyčajnými rozmermi a s drevenými konštrukciami. Mŕtvych pochovaných s kosákom teda musíme zaradiť do vyššej polovice sociálnej hierarchie, čo hroby z avarskej a veľkomoravskej doby najzreteľnejšie ukazovali. Pohrebné zvyky sa potom pod vplyvom prenikavej kresťanísacie zjetnotili a sociálne rozdiely boli menej poznateľné. Význam kosákov v hrobe by teda mohol súvisieť s vyšším sociálnym postavením mŕtveho. Lenže kosák kvôli jeho svojej malej hmotnej hodnote nemôže platiť ako prestížny objekt a musíme vziať do úvahy jeho symbolické reprezentovanie sociálneho statu alebo bohatstva. Avšak kosák aj ako predmet hrobového inventára, zostal pre všetkých viditeľné poľnohospodárské náradie, mohli by sme ho interpretovať napríklad ako symbol pozemkového majetku. Zatiaľ ale chýbajú ešte presné informácie o vývoji vlastníctva a pozemkového pánstva v strednodunajskej oblastí z ranného stredoveku, ktoré by mohli pomôcť d’alej v tejto súvislostí. Vyhodnotenie d’alej ukazovalo, že zvyk, dať kosáky do hroba sa menil v priebehu storočí. Na to poukázalo najprv zreteľné zmenšenie mužských jedincov pochovaných s kosákom (Obr. 9) a častejší výskyt neúplných kosákov (Obr. 10). Okrem toho sa menilo uloženie kosáku v hrobe. Na začiatku boli prevažne uložené do pánvy. Neskôr, predovšetkým od pokročilého 10. stor. až do novoveku sa vyskytli na rozdielných miestach v hrobe (Obr. 11). Pôvodný význam sa teda pravdepodobne menil alebo bol stratený.

In Homer’s work Iliad, Achilles is harassed in the sleep by the ghost of his friend Patroclus who demands a burial by him to be able to find peace. From this we get an understanding of how important it was for the ancient Greeks that their dead were given a proper burial for the soul to enter Hades and be able to find peace. If the deceased body was not buried, the soul became restless that harassed and had the power to harm the living. Infants belong to the group of individuals that do not appear to have had any consistent way of how to deal with them after they died. Some of them did not receive anything even close to a burial that a deceased adult would have received. Why infants were handled differently in certain contexts and locations is a mystery and begs the question of whether they were not considered to be people when they died and what was required to be considered worthy of a funeral when being dead. The purpose of this study was to investigate whether infants ended up in Hades or not, with the ancient Greeks' view of death and dead bodies as a theoretical starting point. To fulfill the purpose, the following questions were asked; how were dead infants handled? Were they considered to be 'real' individuals? How do the dead infants relate to the notions of becoming restless dead? To be able to answer these questions, I researched material from three different categories of evidence. The discussion has been divided into archaeological, iconographical, and literary sources. There are many different answers to the questions of this thesis as the different sorts of source material indicate diverse answers and attitudes to infants. It all probably depends on the different geographical places, economy, and status in society. These different answers also generate different attitudes to infants and whether they in fact were a real person. But through this thesis I have displayed factors that can support my theory about infants in Hades and that they – in worst case scenario – could end up like restless dead.

Artefacts acquire/embody migratory meanings according to contexts of raw material manipulation, use, discard and discourse. First-Millennium Agriculturist ceramics and concomitant private and public significances/use values are placed within aspects of a deep past Stone Age history of space and artefact usage in the Eastern Cape, South Africa. Some thought paradigms and cultural contexts are examined as having directly influenced discourse, what artefacts were foregrounded, and in which manner writers of southern African prehistory considered them. Thereafter ceramic artefacts and associated technologies are focussed upon as being intimate to personal/ community lifeways and worldviews. Domestic and ceremonial utilityware, figurines and masks, as well as clay usage in homebuilding and metalworking, and urges to apply a mark to malleable clay, or deliberately alter and/or bury ceramic artefacts; are explored as manifestations of medium and usage well suited to regularly reconfigured meanings . / Art History, Visual Arts & Musicology / M.A. (Art History)

The purpose of this study is to analyze the distribution, forms, and function(s) of iron amulets deposited in the late Iron Age gravefields of Lovö, with the goal of ascertaining how (and so far as possible why) these objects were utilized in rituals carried out during and after burials. Particular emphasis is given to re-interpreting the largest group of iron amulets, the iron amulet rings, in a more relational and practice-focused way than has heretofore been attempted. By framing burial analyses, questions of typology, and evidence of ritualized actions in comparison with what is known of other cult sites in Mälardalen specifically– and theorized about the cognitive landscape(s) of late Iron Age Scandinavia generally– a picture of iron amulets as inscribed objects made to act as catalytic, protective, and mediating agents is brought to light.

No description available.

The South African Waste Information System (SAWIS) was developed by the Department of Environmental Affairs and Tourism (DEAT) in 2005. This is a system used by government and industry to capture routine data on the tonnages of waste generated, recycled and disposed of in South Africa on a monthly and annual basis. All waste producers and waste management organisations should contribute to this national waste database and should accurately monitor the types and quantities of waste produced and handled. According to DEAT (2006) the need for Data verification is important. DEAT (2006:59) defined the term Data Verification as: "assessing data accuracy, completeness, consistency, availability and internal control practices that serve to determine the overall reliability of the data collected." The aim of the study is to determine a procedure, as well as the nature and extent of internal and external source documents, which could be used in the reconciliation of medical waste quantities from generation to disposal. The key objectives are to determine whether the selected hospitals keep internal records of the quantities of medical waste generated; to reconcile the waste quantities on the internal records with the external records, such as the collection certificates, invoices and waste incineration certificates; to ascertain whether the quantity of medical waste generated is equal to the quantity of waste incinerated and disposed of to determine the ratio factor between the quantity of medical waste before incineration and the quantity of the residue (ashes) after incineration, and to make recommendations on the reconciliation of waste quantities from the point of generation to the point of disposal. The results of the study indicate that the destruction certificate is the proof that the waste that was on-site collected by the service provider has been disposed /treated. Especially as an internal control measure. The health care risk waste (HCRW) management record keeping of quantities of weight as per Hospital A, Hospital B and Hospital C allows the opportunity to analyse the weight per month and per Hospital and per category and to make comparisons. The weakness or the gap however still exist that the waste is not weighed at the point of origin, but at the point where the waste service provider collects the waste onsite. It is from this point onwards that the service level agreement between the hospital and the waste service provider and the document management system and the tracking receipt and the waste collection documents (WCD) becomes relevant and where the quantities of waste per category are for the first time recorded. The hypothesis as stated in Chapter 1 was proven valid. The study concludes that reconciliation and comparison between the collection certificate and the destruction certificate and the monthly invoice is therefore possible, but the risk of mixing of waste and the understating or overstating of waste quantities is still not overcome. / Environmental Sciences / M. Sc. (Environmental management)

Artefacts acquire/embody migratory meanings according to contexts of raw material manipulation, use, discard and discourse. First-Millennium Agriculturist ceramics and concomitant private and public significances/use values are placed within aspects of a deep past Stone Age history of space and artefact usage in the Eastern Cape, South Africa. Some thought paradigms and cultural contexts are examined as having directly influenced discourse, what artefacts were foregrounded, and in which manner writers of southern African prehistory considered them. Thereafter ceramic artefacts and associated technologies are focussed upon as being intimate to personal/ community lifeways and worldviews. Domestic and ceremonial utilityware, figurines and masks, as well as clay usage in homebuilding and metalworking, and urges to apply a mark to malleable clay, or deliberately alter and/or bury ceramic artefacts; are explored as manifestations of medium and usage well suited to regularly reconfigured meanings . / Art History, Visual Arts and Musicology / M.A. (Art History)

Les Etudes Probabilistes de Sûreté (EPS) de niveau 2 en centrale nucléaire visent à identifier les séquences d’événements pouvant correspondre à la propagation d’un accident d’un endommagement du cœur jusqu’à une perte potentielle de l’intégrité de l’enceinte, et à estimer la fréquence d’apparition des différents scénarios possibles.<p>Ces accidents sévères dépendent non seulement de défaillances matérielles ou d’erreurs humaines, mais également de l’occurrence de phénomènes physiques, tels que des explosions vapeur ou hydrogène. La prise en compte de tels phénomènes dans le cadre booléen des arbres d’événements s’avère difficile, et les méthodologies dynamiques de réalisation des EPS sont censées fournir une manière plus cohérente d’intégrer l’évolution du processus physique dans les changements de configuration discrète de la centrale au long d’un transitoire accidentel.<p>Cette thèse décrit l’application d’une des plus récentes approches dynamiques des EPS – la Théorie de la Dynamique Probabiliste basée sur les Stimuli (SDTPD) – à différents modèles de déflagration d'hydrogène ainsi que les développements qui ont permis cette applications et les diverses améliorations et techniques qui ont été mises en oeuvre.<p><p>Level-2 Probabilistic Safety Analyses (PSA) of nuclear power plants aims to identify the possible sequences of events corresponding to an accident propagation from a core damage to a potential loss of integrity of the containment, and to assess the frequency of occurrence of the different scenarios.<p>These so-called severe accidents depend not only on hardware failures and human errors, but also on the occurrence of physical phenomena such as e.g. steam or hydrogen explosions. Handling these phenomena in the classical Boolean framework of event trees is not convenient, and dynamic methodologies to perform PSA studies are expected to provide a more consistent way of integrating the physical process evolution with the discrete changes of plant configuration along an accidental transient.<p>This PhD Thesis presents the application of one of the most recently proposed dynamic PSA methodologies, i.e. the Stimulus-Driven Theory of Probabilistic Dynamics (SDTPD), to several models of hydrogen explosion in the containment of a plant, as well as the developed methods and improvements.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Enfin, le droit international dispose d’un ensemble de règles relatives à la responsabilité des organisations internationales pour fait internationalement illicite. Après 10 ans de travail, la Commission du droit international est parvenue, en 2011, à élaborer un projet d'articles codifiant les règles en la matière. La tâche était pourtant délicate : assujettir ces entités dont la nature et le fonctionnement sont différents des Etats, à un ensemble de règles unique dans le domaine de la responsabilité internationale. L’objet de cette étude porte sur l’œuvre de codification effectuée par la Commission dans le projet d’articles. Il s’agit plus précisément d’analyser les techniques de codification utilisées par la Commission dans l’élaboration des règles applicables : s’agit-il d’une codification stricto sensu de la pratique ou bien de l’élaboration de nouvelles règles relevant du « développement progressif » du droit international ? La réponse apportée à cette question suppose préalablement de définir les sources de la codification en ce qui concerne chacune des dispositions du projet d’articles, en se demandant si elle concrétise une pratique bien établie des organisations internationales, ou au contraire une transposition des règles du projet d’articles sur la responsabilité de l’Etat, adaptées aux particularités des organisations internationales. L’autorité du projet d’articles ne semble pas, à l’heure actuelle, faire l’unanimité, et dans ce contexte, la présente étude portant sur le rapport entre codification et développement progressif dans l’œuvre de codification de la CDI permet d’apprécier l’autorité substantielle propre à chacune des dispositions du projet d’articles. D’autant qu’on ne sait absolument pas si une convention de codification sera adoptée, qui pourra ériger les dispositions du projet d’articles en normes juridiquement obligatoires. / The international law has finally a set of rules on the responsibility of the international organizations for internationally wrongful acts. After 10 years of work, the International Law Commission was able in 2011 to elaborate a draft articles codifying the rules on the matter. However the task was difficult: subject these entities, whose nature and functioning is different from States to a single set of rules in the field of international responsibility. The purpose of this study focuses on the work of codification made by the Commission in the draft articles. This is specifically to analyze the techniques of codification used by the Commission in the elaboration of the applicable rules: is it a codification sticto sensu of the practice or a creation of new rules under the "progressive development" of the international law? The answer to this question presupposes to define the sources of codification in each of the provisions of the draft articles concerned, wondering if it embodies a well-established practice of international organizations, or rather a transposition of the rules of the draft articles on States responsibility, adapted to the features of international organizations. At present the authority of the draft articles does not seem to have unanimity, and in this context, the present study on the relation between codification and progressive development in the codification work of ILC can appreciate the substantial own authority of each provisions of the draft articles. Especially that no one knows if a codification convention will be adopted, which will set the provisions of the draft articles up as legally binding norms.