The Hochschild cohomology of an associative algebra records information about the deformations of that algebra, and hence the first step toward understanding its deformations is an examination of the Hochschild cohomology. In this dissertation, we use techniques from homological algebra, invariant theory, and combinatorics to analyze the Hochschild cohomology of skew group algebras arising from finite cyclic groups acting on polynomial rings over fields of arbitrary characteristic. These algebras are the natural semidirect product of the group ring with the polynomial ring. Many families of algebras arise as deformations of skew group algebras, such as symplectic reflection algebras and rational Cherednik algebras. We give an explicit description of the Hochschild cohomology governing graded deformations of skew group algebras for cyclic groups acting on polynomial rings. For skew group algebras, a description of the Hochschild cohomology is known in the nonmodular setting (i.e., when the characteristic of the field and the order of the group are coprime). However, in the modular setting (i.e., when the characteristic of the field divides the order of the group), much less is known, as techniques commonly used in the nonmodular setting are not available.

In western countries, we are now living in a period of economic prosperity. This has undermined in a certain way the “world’s balances” in terms of social, economic and well-being equilibrium. In particular, well-being grows in parallel with its side effects: it allows the population to grow, which generates a rise of the resources need, with related risk of pauperization of the planet. The two main aspects of the current world’s living system crisis are climate change and widespread poverty, even and mainly in terms of lack of housing. Until some years ago one was the cause of the other: the building sector is the most energy consumer and CO2 emitter. Anyway, thanks to the contemporary knowledge and technology, this trend is inverted: it is now quite simple, and in several countries compulsory, to realize NZEB or ZEB constructions. However, especially in growing countries, the building industry is yet too slow to meet the contemporary changes which are consistently faster and pressing. The main theme is now to explore the possibility of generating a new building system which can be fast in construction, adaptable to changes and completely fade away. It must respond either to growing needs or to change during the time. All focusing on very low energy consumption in use and to production/disposal phases.

This project is examining the possibility of reusing a space taken by a transportation structure, the Nuselský most, a bridge located in Prague, and speculates about its uses in a carless future.  A bridge structure is perceived as a connection, a shelter, or a barrier, but how can we use the space In Between the Bridge? The project is connecting future living desires with remains from the past and utilizing a structure that might become obsolete while proposing a vertical community for a post-materialistic generation oriented towards health, nature, self-realization, individualism, and sustainability, supporting social interactions in society.It is an investigation of an ability of a structure to be flexible in response to the demands of society and the ability to expand over time while using space already taken by the bridge. Modularity is used as a tool to achieve higher freedom in populating the void and in combining different typologies in one structure. Relation between horizontal and vertical city life is presenting new opportunities for community meeting points, unexplored urban spaces, and forming new connections within the city.

This study delves into the development of a long-term, sustainable housing solution to address the challenges faced during crisis when people are in immediate need of an accommodation. While temporary tents have been traditionally employed as shelters, their inefficiency in colder climates and lack of sustainability necessitate the exploration of alternative options. The proposed solution focuses on the construction of permanent houses equipped with proper insulated floorings, walls, and roofs.  Several crucial factors are taken into consideration throughout this study, including resistance to biological decomposition, exposure to precipitation, breathability, U-value per thickness, storage capabilities, and environmental impact. Therefore, studies and simulations are conducted to evaluate the viability of two organic insulation materials, with the objective of identifying the most suitable option for the project. In the next step energy simulations are conducted using the VIP software, enabling an accurate assessment of the concept building's energy efficiency. Moreover, a detailed model of the housing prototype is constructed using Revit and rendered using Twinmotion, facilitating a comprehensive visualization of the final design. Additionally, the transportation of the developed housing units was investigated and an efficient storage concept for standard shipping container was developed and modelled in SketchUp. With this study a sustainable, lightweight, flexible, adaptable, and easily transportable housing solution that can be constructed without reliance on external forces is to develop. By emphasizing sustainability and resilience, this study provides dignified and long-lasting housing for individuals and communities in need, effectively bridging the gap between temporary shelters and permanent housing structures. The findings and insights obtained from this study contribute to the broader body of knowledge in the field, fostering future advancements in crisis housing and promoting sustainable development practices.

With the increasing maturity and flexibility of power electronics-based voltage conversion techniques, DC grids, and distribution systems have gained significant interest. These systems offer advantages such as improved power quality, efficiency, and flexibility. Medium-voltage DC (MVDC) applications, including shipboard, railway systems, distribution networks, and microgrids, are emerging as critical areas of interest. To integrate MVDC systems with existing power grids, MV AC/DC conversion techniques are crucial. Moreover, the lack of mature protection strategies and equipment, particularly DC circuit breakers (DCCB), poses a significant challenge to the development of MVDC systems. Therefore, this thesis aims to address two primary challenges in the field: the improved topologies of MV AC/DC conversion techniques for interfacing MVDC systems with power grids and the development of high power density DCCB for MVDC systems. The traditional modular multilevel converter (MMC) is widely used for medium voltage (MV) AC/DC conversion due to its modularity, scalability, and reliability. However, the presence of numerous semiconductor devices and capacitors in MMCs results in challenges such as low power efficiency and density. To enhance the performance of MMCs, this thesis proposes several novel hybrid MMC (HMMC) topologies, including the three-level HMMC, flying capacitor HMMC, and hybrid-leg MMC. These topologies aim to leverage the advantages of both conventional multilevel converters and MMCs. By replacing the low-voltage (LV) submodule (SM) in MMCs with a simple high-voltage (HV) switch, higher efficiency, a smaller footprint, and lower cost can be achieved. The HV switch operates at line frequency, simplifying device-switching and addressing the challenges of series-connected devices. The introduction of additional HV switches enables alternative connections compared to traditional MMCs, reducing the number of required SMs. Consequently, there is a significant reduction in the number of semiconductor devices, capacitor energy storage, and power losses. Furthermore, an average model is developed for the three-level HMMC to illustrate the additional power flow path between the AC and DC sides, as well as the reduced SM capacitor energy storage requirement. As a result, the proposed HMMCs exhibit substantial potential to replace traditional MMCs, offering higher efficiency and power density. Unidirectional high-voltage (HV) and medium-voltage (MV) rectifiers are essential for applications where power flows exclusively from the AC to the DC side. Examples of such applications include HVDC transmission, front-end converters for electric vehicle (EV) charging stations, and data centers. Therefore, hybrid modular multilevel rectifiers (HMMRs) are proposed for these unidirectional AC/DC applications. Instead of utilizing active devices for HV switches, the HMMR employs HV diode to achieve step-up HMMR, step-down HMMR, and flying capacitor HMMR configurations. As diodes are passive devices that do not require gate driver units, the HMMR design becomes simpler, resulting in cost and volume savings. Additionally, voltage sharing among the HV diode stack becomes more manageable as concerns regarding gate signal mismatch are eliminated. However, it is important to note that diodes lack current interruption capability. This limitation requires further investigation, particularly in non-unity power factor (PF) operations, which may impose restrictions on the operational range of the rectifiers. In terms of medium voltage (MV) DC circuit breakers (DCCB), this paper introduces the concept and design procedure of a high-power-density, modular, and scalable power electronic interrupter (PEI) for MV hybrid circuit breakers (HCB). The analysis includes trade-offs and limiting factors of various components within a single PEI module. A prototype of a 12 kV, 1 kA breaking-capable PEI is constructed, and new staged turn-off strategies are proposed to ensure the balanced distribution of metal-oxide varistor (MOV) energy. The developed PEI achieves a peak power density of 7.4 kW/cm$^3$, much higher than the solution based on the IGBT modules. After integrating the developed PEI into a full-scale HCB, the breaking capability of the developed PEI and the effectiveness of the staged turn-off strategy are validated. Furthermore, the scalability of the HCB is evaluated, which can simplify the design process from a low-voltage HCB to a higher-voltage version. For series-connected devices in SSCB or HCB configurations, the conventional gate driver structure necessitates an individual gate driver unit, fiber-optic, and isolated power supplies for each device. This design increases cost and volume, particularly for this single-pulse application. To address this issue, two new single gate driver structures are proposed to reduce component count and system complexity. The first solution, namely the MOV-coupled structure, employs a metal-oxide varistor (MOV) for the turn-off path. On the other hand, the transformer-coupled structure combines the auxiliary power and gate signal, enabling both simultaneous and staged turn-off schemes. Moreover, the cascaded high- and lower-voltage transformer structure simplifies insulation design and demonstrates improved scalability. These proposed gate driver structures aim to streamline the system, reduce component numbers, and simplify control for series-connected devices, leading to cost savings and improved overall performance. / Doctor of Philosophy / The advent of modern power electronics has paved the way for the implementation of medium-voltage (MV) DC systems, which offer advantages such as improved power quality, efficiency, and flexibility. However, the development of advanced AC/DC power conversion techniques and MVDC distribution system equipment, particularly MV DC circuit breakers (DCCBs), poses significant challenges for future MVDC systems. While the modular multilevel converter (MMC) is considered one of the best solutions, it suffers from a large number of devices and submodules (SMs). To overcome this limitation, novel topology concepts are introduced by combining high-voltage (HV) switches with low-voltage SMs, which leverage the benefits of both MMC and conventional multilevel converters. Several Hybrid MMC (HMMC) topologies, such as the three-level HMMC, flying capacitor HMMC, and hybrid-leg MMC, have been proposed. The introduction of additional HV switches enables different configurations over one line cycle, reducing the number of SMs and achieving higher power density and efficiency compared to the traditional MMC. Moreover, for unidirectional power flow, the hybrid modular multilevel rectifiers (HMMRs) can be derived by replacing the HV switch with HV diodes. This modification further reduces cost and volume compared to bidirectional converters. However, the non-unity power factor operation is different from the HMMC version, and more investigation is carried out in this work. As for MV DCCBs, the concept and design procedure of a compact, modular, and scalable power electronic interrupter (PEI) for MV hybrid circuit breakers (HCBs) are discussed. Additionally, two single gate driver structures are proposed to simplify the gate driver design, leading to a significant reduction in component count and cost. These advancements in topology solutions, MV DCCBs, and gate driver structures hold promise for the development of efficient and cost-effective MVDC systems.

Der zementfreie modulare Hüftrevisionsschaft Revitan® ist ein seit vielen Jahren verfügbares und relativ häufig verwendetes Implantat. Die Vorteile der modularen Revisionsschäfte gegenüber einkomponentigen Revisionsschäften (u.A. die bessere Anpassbarkeit an die jeweilige Anatomie) gehen jedoch mit einem erhöhten Risiko für einen Bruch an der Verbindungsstelle der distalen und proximalen Komponente einher. So wurde in den vergangenen Jahren in der Literatur vermehrt von Brüchen des Revitan-Schaftes im Bereich der Konusverbindung berichtet. Ziel der hier vorliegenden retrospektiven Arbeit war die Ermittlung der Rate an Schaftbrüchen in einer Kohorte von 223 Implantaten, sowie die Gewinnung weiterer klinischer und radiologischer Langzeitergebnisse über das Schaftsystem. Die Studie betrachtet alle 223 Revitan-Schäfte, die im Zeitraum von 2008 bis 2013 im Dresdener UniversitätsCentrum für Orthopädie, Unfall- und Plastische Chirurgie implantiert wurden. Die Patienten wurden zu einer klinischen Nachuntersuchung oder brieflichen Befragung eingeladen. Es wurden eine körperliche Untersuchung sowie Röntgenbilder der Hüften durchgeführt, die mit den postoperativen Röntgenbildern verglichen werden konnten. Der mittlere Nachuntersuchungszeitraum betrug 8,3 Jahre, mit einem Minimum von 6,1 Jahren und Maximum von 11,3 Jahren (SD 1,4). Die statistische Analyse ergibt eine Rate an Schaftbrüchen von 2,7 %. Als signifikante Einflussfaktoren identifiziert die Studie die Verwendung von kurzen proximalen Schaftkomponenten, Hüftkopfadapterlängen ≥3XL sowie einen fehlenden proximalen knöchernen Support der Prothese. Das Langzeitüberleben mit dem Endpunkt „Schaftversager“ lag bei 84,9 % nach 11,3 Jahren. Die Schaftsinterungsrate > 5 mm betrug 2,17 %. Der WOMAC Score ergab 70,4 Punkte (± 21,2). Der EuroQol-5D Index erzielte im Mittelwert 0,74 von 1 (SD 0,24) und in der visuellen Analogskala (VAS) ergab sich ein Mittelwert von 58,48 von 100 (SD 22,25). Der Harris Hip Score betrug vor der Operation 44,1 (± 17,9) und bei der Nachuntersuchung 65,9 Punkte (± 19,7). Der Revitan-Schaft weist in dieser Untersuchung unter Berücksichtigung der oft sehr komplexen Ausgangslagen der behandelten Patienten insgesamt ein zufriedenstellendes Langzeitüberleben auf. Allerdings ist die Rate an Brüchen der modularen Verbindungsstelle deutlich höher als in vergleichbaren Untersuchungen. Aufgrund dieser Ergebnisse empfiehlt sich bei der Implantation eines Revitan-Schaftes die Vermeidung kurzer proximaler Komponenten und extralanger Hüftkopfadapter, da ihre Verwendung das Risiko eines Schaftbruches erhöht. Zusätzlich sollte auf einen ausreichenden Knochen-Prothesen-Kontakt medial der proximalen Schaftkomponente geachtet werden.:Inhalt Tabellenverzeichnis VI Abbildungsverzeichnis VII Abkürzungsverzeichnis IX Disclaimer gendergerechte Sprache X 1 Einleitung 1 1.1 Revisionsoperationen in der Hüftendoprothetik 1 1.2 Darstellung des Revitan-Systems 3 1.2.1 Allgemeines 3 1.2.2 Schaftkomponenten 3 1.2.3 Implantation und Fixationsprinzipien 7 1.2.4 Verbindungskonus 9 1.3 Schaftbruch bei modularen Revisionsschäften 10 1.4 Hüftköpfe und Hüftkopfadapter 12 1.5 Studienziel und Forschungsfragen 13 2 Material und Methoden 14 2.1 Studiendesign 14 2.2 Studienpopulation 15 2.2.1 Patienten 15 2.2.2 Präoperative Diagnosen 17 2.2.3 Operationen und Implantate 18 2.3 Erhebungsinstrumente 23 2.3.1 Klinische Nachuntersuchung 23 2.3.2 Fragebögen 23 2.3.3 Röntgenauswertung 25 2.4 Primäre und sekundäre Endpunkte 27 2.5 Statistik 28 3 Ergebnisse 29 3.1 Primärer Endpunkt Schaftbruch 29 IV 3.1.1 Beschreibung der sechs Patienten mit Konusbruch 29 3.1.2 Einflussfaktoren auf den Schaftbruch 33 3.2 Sekundärer Endpunkt Langzeitüberleben 37 3.2.1 Anzahl und Ursachen der Revisionsoperationen insgesamt 37 3.2.2 Beschreibung der 26 Patienten mit Schaftversagen 39 3.2.3 Röntgenauswertung 41 3.3 Tertiärer Endpunkt: Ergebnisse der Fragebögen 43 3.3.1 WOMAC, EuroQol-5D 43 3.3.2 Harris Hip Score 45 3.3.3 UCLA Aktivitätsscore 46 3.3.4 Charnley-Klassifikation 47 3.3.5 Zufriedenheit mit dem OP-Ergebnis ja/nein 49 3.3.6 OP noch einmal? 51 4 Diskussion 52 4.1 Eigene Ergebnisse 52 4.2 Bisherige Revitan-Studien 53 4.3 Vergleich der Bruchrate 55 4.4 Vergleich der Einflussfaktoren Schaftbruch 56 4.4.1 Einfluss der Länge der proximalen Komponente und des Hüftkopfadapters 57 4.4.2 Einfluss des medialen Supportes 58 4.4.3 Einfluss der Form der distalen Komponente 59 4.4.4 Einfluss des Geschlechts 59 4.4.5 Einfluss des BMI 60 4.4.6 Einfluss des Patientenalters 60 4.4.7 Einfluss der ASA-Klassifikation 60 4.5 Vergleich des Langzeitüberlebens 60 4.5.1 Schaftversager 61 4.5.2 Komplikationsrate 62 4.6 Vergleich der Röntgenauswertung 64 4.6.1 Sinterung 64 V 4.6.2 Medialer Support 65 4.6.3 Heterotope Ossifikation 65 4.7 Vergleich der Ergebnisse der Fragebögen 65 4.7.1 WOMAC 65 4.7.2 Harris Hip Score 66 4.7.3 EuroQol-5D-3L, UCLA Aktivitätsscore 66 4.7.4 Zufriedenheit mit dem OP-Ergebnis 67 4.8 Fazit 69 4.9 Ausblick 69 4.10 Limitierungen der Arbeit 71 5 Zusammenfassung 72 6 Literaturverzeichnis 74 7 Danksagung 82 8 Anhang 83 8.1 Patientenaufklärung 83 8.2 Zustimmungserklärung 84 8.3 Datenschutzerklärung 85 8.4 Fragebogen klinische Nachuntersuchung 86 9 Anlage 1: Erklärung zur Eröffnung des Promotionsverfahrens 93 10 Anlage 2: Bestätigung über Einhaltung der aktuellen gesetzlichen Vorgaben 94 / The modular Revitan® hip revision system is a cementless implant that has been available for many years and is used relatively frequently. However, the advantages of modular revision stems over single-component revision stems (including better adaptability to the patient’s respective anatomy) are accompanied by an increased risk of fracture at the junction of the distal and proximal components. Thus, fractures of the Revitan stem in the area of the taper junction have been increasingly reported in the literature in recent years. The aim of the retrospective work presented here was to determine the rate of stem fractures in a cohort of 223 implants, as well as to obtain further long-term clinical and radiological results on the revision system. The study considered all 223 Revitan stems implanted at the Dresden University Center for Orthopaedics, Trauma and Plastic Surgery from 2008 to 2013. Patients were invited to participate in a clinical follow-up or mail survey. A physical examination and radiographs of the hips were performed and compared with postoperative radiographs. The mean follow-up period was 8.3 years, with a minimum of 6.1 years and maximum of 11.3 years (SD 1.4). Statistical analysis reveals a rate of stem fractures of 2.7 %. The study identifies the use of short proximal stem components, femoral head adapter lengths ≥3XL, and lack of proximal bony support of the prosthesis as significant influencing factors. Long-term survival with the endpoint “stem failure” was 84.9 % after 11.3 years. The stem sintering rate > 5 mm was 2.17 %. The WOMAC score was 70.4 points (± 21.2). The EuroQol-5D index mean score was 0.74 of 1 (SD 0.24), and the visual analog scale (VAS) mean score was 58.48 of 100 (SD 22.25). The Harris hip score was 44.1 (± 17.9) before surgery and 65.9 points (± 19.7) at follow-up. The Revitan stem demonstrates satisfactory overall long-term survival in this study, considering the patients’ often very complex initial conditions. However, the rate of fractures of the taper junction is significantly higher than in comparable studies. Based on these results, it is recommended to avoid short proximal components and extra-long femoral head adapters when implanting a Revitan stem, as their use increases the risk of stem fracture. In addition, care should be taken to ensure adequate bone-prosthesis contact medial to the proximal stem component.:Inhalt Tabellenverzeichnis VI Abbildungsverzeichnis VII Abkürzungsverzeichnis IX Disclaimer gendergerechte Sprache X 1 Einleitung 1 1.1 Revisionsoperationen in der Hüftendoprothetik 1 1.2 Darstellung des Revitan-Systems 3 1.2.1 Allgemeines 3 1.2.2 Schaftkomponenten 3 1.2.3 Implantation und Fixationsprinzipien 7 1.2.4 Verbindungskonus 9 1.3 Schaftbruch bei modularen Revisionsschäften 10 1.4 Hüftköpfe und Hüftkopfadapter 12 1.5 Studienziel und Forschungsfragen 13 2 Material und Methoden 14 2.1 Studiendesign 14 2.2 Studienpopulation 15 2.2.1 Patienten 15 2.2.2 Präoperative Diagnosen 17 2.2.3 Operationen und Implantate 18 2.3 Erhebungsinstrumente 23 2.3.1 Klinische Nachuntersuchung 23 2.3.2 Fragebögen 23 2.3.3 Röntgenauswertung 25 2.4 Primäre und sekundäre Endpunkte 27 2.5 Statistik 28 3 Ergebnisse 29 3.1 Primärer Endpunkt Schaftbruch 29 IV 3.1.1 Beschreibung der sechs Patienten mit Konusbruch 29 3.1.2 Einflussfaktoren auf den Schaftbruch 33 3.2 Sekundärer Endpunkt Langzeitüberleben 37 3.2.1 Anzahl und Ursachen der Revisionsoperationen insgesamt 37 3.2.2 Beschreibung der 26 Patienten mit Schaftversagen 39 3.2.3 Röntgenauswertung 41 3.3 Tertiärer Endpunkt: Ergebnisse der Fragebögen 43 3.3.1 WOMAC, EuroQol-5D 43 3.3.2 Harris Hip Score 45 3.3.3 UCLA Aktivitätsscore 46 3.3.4 Charnley-Klassifikation 47 3.3.5 Zufriedenheit mit dem OP-Ergebnis ja/nein 49 3.3.6 OP noch einmal? 51 4 Diskussion 52 4.1 Eigene Ergebnisse 52 4.2 Bisherige Revitan-Studien 53 4.3 Vergleich der Bruchrate 55 4.4 Vergleich der Einflussfaktoren Schaftbruch 56 4.4.1 Einfluss der Länge der proximalen Komponente und des Hüftkopfadapters 57 4.4.2 Einfluss des medialen Supportes 58 4.4.3 Einfluss der Form der distalen Komponente 59 4.4.4 Einfluss des Geschlechts 59 4.4.5 Einfluss des BMI 60 4.4.6 Einfluss des Patientenalters 60 4.4.7 Einfluss der ASA-Klassifikation 60 4.5 Vergleich des Langzeitüberlebens 60 4.5.1 Schaftversager 61 4.5.2 Komplikationsrate 62 4.6 Vergleich der Röntgenauswertung 64 4.6.1 Sinterung 64 V 4.6.2 Medialer Support 65 4.6.3 Heterotope Ossifikation 65 4.7 Vergleich der Ergebnisse der Fragebögen 65 4.7.1 WOMAC 65 4.7.2 Harris Hip Score 66 4.7.3 EuroQol-5D-3L, UCLA Aktivitätsscore 66 4.7.4 Zufriedenheit mit dem OP-Ergebnis 67 4.8 Fazit 69 4.9 Ausblick 69 4.10 Limitierungen der Arbeit 71 5 Zusammenfassung 72 6 Literaturverzeichnis 74 7 Danksagung 82 8 Anhang 83 8.1 Patientenaufklärung 83 8.2 Zustimmungserklärung 84 8.3 Datenschutzerklärung 85 8.4 Fragebogen klinische Nachuntersuchung 86 9 Anlage 1: Erklärung zur Eröffnung des Promotionsverfahrens 93 10 Anlage 2: Bestätigung über Einhaltung der aktuellen gesetzlichen Vorgaben 94

In this licentiate thesis, we study the action of Hecke operators on Drinfeld cusp forms via the theory of crystals over function fields. The thesis contains one preliminary chapter, in which we recall some basic theory of Drinfeld modules and Drinfeld modular forms, as well as the Eichler-Shimura theory developed by Böckle. The core of the thesis consists of Chapter II, in which we prove a Lefschetz trace formula for crystals over stacks and deduce a Ramanujan bound for Drinfeld modular forms, and Chapter III, in which we compute traces and slopes of Hecke operators. We formulate several questions and conjectures based on our data. We also include an appendix in which we discuss the relationship between traces of an operator in positive characteristic and its eigenvalues.

Around the world, countries are increasingly considering carbon-free energy generation options as the threat of climate change grows. Small modular reactor designs, promising such carbon-free energy generation, are thriving worldwide with novel and innovative technologies that improve safety as well as economic performance. Canada is also considering small modular reactors (SMRs) as a means of achieving net zero carbon emissions by 2050. Some of these reactor designs utilize pressurized water for cooling and moderator. Reactors with pressurized water have been subjected to steam generator tube ruptures in the past, and a detailed investigation into the possible consequences of such incidents in SMRs should be conducted. In this research, a model for one of the newer designs, the NuScale Integrated Small Modular Reactor, was developed with the RELAP5-3D code for assessing safety related transients. The NuScale Small Modular Reactor incorporates helical coil steam generators within its reactor pressure vessel, which are more efficient in terms of heat transfer than the U-tube steam generators that are widely used in nuclear reactors. In the first part of the research, a detailed model is created and used to obtain steady state conditions with parameters collected from NuScale’s Final Safety Analysis Report (FSAR). The Steam Generator Tube Rupture event is analyzed in the second part of the work. Slight differences in the broken and intact steam generator pressures as well as decay heat removal system flow rates are seen in the comparison of reference values and calculated results. Among the reasons for those differences could be that the correlations used by the RELAP5-3D code for heat transfer coefficient and pressure drop in the helical coil steam generators are different than those of the NuScale proprietary code NRELAP5, with which the analyses have been performed in the FSAR. Also, post-dryout heat transfer at the exit of helical coil steam generators and evaporator sections could cause differences in the outlet conditions of the steam, resulting in different mass flow rates as well. The final section of the research simulates a comparable but more severe tube rupture incident without the availability of decay heat removal systems in order to assess the reactor’s emergency core cooling system reaction. Passive decay heat removal systems are crucial components for removing heat after reactor shutdown through heat exchangers that are submerged in the reactor pool and connected to steam generators by a closed loop. The containment pressures, the containment wall temperatures, and the peak fuel clad temperatures are considered to be the key design constraints that must be observed. Future work on this subject could include modifying the source code, adding specific correlations for helical coil steam generators, and comparing the results, as well as quantifying uncertainties in the SGTR event. Main parameters in the quantification of uncertainties would be reactor power, single phase and two-phase discharge coefficients from the break, trip signals and delays as well as break size and location. / Thesis / Master of Applied Science (MASc)

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