As intermittent renewable energy sources such as wind and solar power gradually increase around the world, older technologies such as nuclear power is phased out in Sweden and many other countries. It is then important to ensure that the total power need is secured, and that the power grid can remain stable. One way of managing intermittent renewables is by using energy storage. The main goal of this thesis was to compare energy storage methods and their costs. A secondary aim was to investigate how the cost of developing more renewable energy sources, in combination with different energy storage methods, compares to erecting new nuclear power. This thesis was limited to three energy storage technologies, namely pumped hydro storage (PHS), compressed air energy storage (CAES), and four battery storage technologies. They were combined with wind power in the cost analysis. The comparison was done by performing a literature review and economical calculations, which focused especially on levelized cost of storage (LCOS). The results from the economic calculations indicated that PHS and CAES had lower LCOS than battery storage technologies. Similar results could be seen in the literature review as well. When comparing levelized cost of energy (LCOE) nuclear power had the lowest, €0.03-0.12 kWh-1, followed by wind power in combination with PHS and CAES, both around €0.07-0.24 kWh-1. This result was maintained also at sensitivity analysis regarding the discount rate, which both nuclear power and PHS proved rather sensitive to. Keywords: energy storage, nuclear power, wind power, pumped hydro storage, compressed air energy storage, battery energy storage, levelized cost of energy, Sweden

This diploma thesis focuses on the changes in the media image of nuclear power in Ceska Televize, which is the only public television in Czech Republic. The study uses a quantitative research method, content analysis, to find out the changes of nuclear power representation in media and to compare changes of news construction mechanisms in the period of two years - one year before and one year after the Japanese nuclear power plant Fukushima Daiichi disaster. The accident started on 11th March 2011 and there is a short description of the situation in Japan at the beginning of the thesis. The theoretical part of thesis serves as an overview of basic information on principles of the media studies theory and mechanisms of news construction (work with information sources, the news value concept, agenda setting, the framing concept), which is also shown from the environmental point of view. The study also focuses on the nuclear power image in the socio-political field and there are some more information about the nuclear power development and status in Czech Republic. The analytical part of thesis examines the media attention to nuclear power, which was developed in the analysed period. The usage of mechanisms of news construction and the changes in nuclear power image in the news of Ceska Televize...

The current model for electricity generation is based on power plants connected to the transmission network. This provides electricity to the distribution network and after that to the consumers. To ensure the security of the electrical network and prevent a blackout, the performance of every electricity generation unit connected to the network is quantified in grid codes. In the case of the French transmission system, the requirements regarding the performance are written in a document produced by the French Transmission System Operator (TSO). Various events with various configurations of connection to the network have to be simulated and the corresponding performance has to be evaluated. The aim of these simulations is to determine the stability of the generators and key elements, including the response time on the active power after events such as a short circuit.Taking into account the amount of generators connected to the transmission network, the need for optimization appears and is the purpose of this Master Thesis. To perform those simulations in an efficient way on all the generators owned by the main French electricity producer, EDF, this Master Thesis contributes with a tool called AuDySim coded with the softwares MATLAB and EUROSTAG. The implemented tool allows the user to configure an electricity generation unit before realizing all the simulations specified by the TSO and produces a report containing the results by means of curves and data. The simulations and the production of the report are achieved automatically to create a gain of time and resources.In order to validate the performance of the tool, two case studies are performed on different types of power plants. The two case studies analyzed present a hydraulic and a nuclear power plant. In the results the performance of each type of power plant is assessed focusing on the rotor angle stability of the machine and key elements, such as the voltage and the active power. These results lead to the conclusion that AuDySim fulfills its mission, by achieving automatically an analysis of the performance of an electrical generation unit and producing it in a report. / Den nuvarande elproduktionsmodellen baseras på kraftverk som är direktkopplade till stamnätet. Stamnätet i sin tur matar distributionsnätet som därefter levererar el till slutkonsumenterna. För att säkerställa stamnätets integritet samt säkerhet och undvika strömavbrott kvantifieras prestandan hos varje generator som är ansluten till det med hjälp av nätkoder. När det gäller det franska stamnätet skrivs prestandakraven i ett dokument som utfärdas av den franska transmissionssystemoperatören (TSO). Olika händelser med olika anslutningskonfigurationer måste simuleras där dess prestanda ska utvärderats. Syftet med dessa simuleringar är att identifiera stabiliteten vid varje elproduktionsenhet med bl. a. dess reaktionstid för den aktiva effekten efter kortslutningar.Med tanke på antalet generatorer som är anslutna till stamnätet framträder ett behov för överföringsoptimering vilket är syftet med detta examensarbete. För att utföra dessa simuleringar på ett effektivt sätt på alla generatorer som ägs av den ledande franska elproducenten, EDF, bidrar denna avhandling med ett verktyg som heter AuDySim kodat i mjukvarorna MATLAB och EUROSTAG. Verktyget gör det möjligt för användaren att konfigurera en elproduktionsenhet innan man utför alla simuleringar som specificeras av TSO:n och samtidigt producerar en rapport som innehåller grafisk- och data resultat. Både simuleringar och rapporten produceras automatiskt för att optimera en bearbetningstid och resursanvändning.För att validera verktygets prestanda utförs två fallstudier på olika typer av kraftverk. De två fallstudierna fokuserar på ett hydraulisk- respektive ett kärnkraftverk. I resultaten utvärderas prestanda för varje typ av kraftverk, med fokus på maskinens rotorvinkelstabilitet och andra viktiga faktorer, såsom spänning och aktiv effekt. Resultat leder till slutsatsen att AuDySim uppfyller sitt uppdrag genom att automatiskt analysera prestanda hos en elektrisk generationsenhet och presentera analysen i en rapport.

In this master thesis an input-model of a Nordic BWR power plant has been developed in APROS. The plant model contains key systems and major thermohydraulic components of the steam cycle, including I&C systems (i.e. power, pressure, level and flow controls). The plant model is primarily designed for balance of plant studies at discrete power levels. The input-model of the power plant focuses especially on the steam cycle which is crucial for analysing water and steam behaviour and its influence on the reactor power. At the current stage, the model primarily handles steady-state conditions of full-power operation, which has been the design point. It has also been shown that reduced-power operation can be simulated with a reasonable trendline of pressure and temperature progression over facility components. / Inom ramen för examensarbete har en indatafil (modell) av en nordisk kokvattenreaktor, BWR, utvecklats i simuleringsverktyget APROS. Anläggningsmodellen är främst utformad för att simulera diskreta effektnivåer och innehåller viktiga system och termohydrauliska komponenter som ingår i ångcykeln, inklusive instrumenterings- och kontrollutrustning (dvs. effekt-, tryck-, nivå- och flödesreglering). Fokus har lagts särskilt på att få till en bra representation av ångcykeln, vilket är avgörande för analys av vatten- och ångbeteendet och dess påverkan på reaktoreffekten. Modellen kan främst användas för simulering av jämviktstillstånd vid full effektdrift och till en viss grad även reducerad effektdrift.

This project deals with two-phase CFD model validation, a subject which is currently under active research due to its complexity. The goal is to create a model that predicts data profiles to an acceptable degree for a wide array of flow conditions. The applications within the nuclear field would mainly be for safety analysis, e.g. to predict phenomena such as the critical heat flux. The underlying physics were investigated, and simulations were performed of two-phase flow of the coolant R12 using the program OpenFOAM in an attempt to match radial profiles of void fraction, interfacial area concentration, vapour velocity and sauter mean diameter for different flow conditions provided by the DEBORA experiments. The proper set of models was found via sensitivity testing: trying combinations of different models and model coefficients. The effect on the simulation result was investigated, with the models that improved the result kept while the rest were discarded. The main strategy was to find models that accurately predicted the sauter mean diameter, as initial sensitivity tests showed the result to be highly dependent on this parameter. The impact of initial conditions and mesh refinement was also investigated, and a temperature validation study was done. The process was aided by a number of Matlab programs written by the author, to calculate and verify inputs and to post-process the result. A model was found that simulated the subcooled nucleate boiling datasets to an acceptable degree. The model failed to accurately simulate saturated nucleate boiling. / Detta projekt behandlar tvåfas CFD-modellvalidering, ett ämne som fortfarande ärunder aktiv forskning på grund av sin komplexitet. Syftet är att utveckla en modellsom förutser dataprofiler till en acceptabel grad för en mängd olika flödesregimer.Inom kärnkraftsbranchen skulle detta primärt vara applicerbart inom reaktorsäkerhet,t.ex. för att förutse fenomen så som critical heat flux. Den underliggande fysikenundersöktes, och simuleringar genomfördes på tvåfas flöde av kylmedlet R12 med hjälpav programmet OpenFOAM i ett försök att matcha 14 dataprofiler för void fraction,interfacial area, vapour velocity och sauter mean diameter för olika flödesregimertillhandahålla av DEBORA-experimenten.Den rätta uppsättningen modeller fanns via känslighetsanalys, genom att testa olikakombinationer av modeller och modellkoefficienter. Deras effektersimuleringsresultatet undersöktes, och de modeller som förbättrade resultatet behölls,medans resten förkastades. Huvudstrategin var att hitta modeller som förutsåg sautermean diameter, bubblornas medeldiameter, väl, då preliminär känslighetsanalysvisade att resultaten var mycket känsliga på denna parameter. Inflytandet avinitialvillkor och mesh-förfining undersöktes, och en temperaturprofilsvalideringgenomfördes. Till hjälp i processern var ett antal Matlab-program skrivna avförfattaren för att beräkna och verifiera inmatning och behandla och visualiserautdatan. En modell hittades som simulerade underkyld kokning till en acceptabel grad.Modellen misslyckades med att träffsäkert simulera mättad kokning.

The electricity market is facing major changes in the coming years, with major production facilities that must be replaced and climate targets that are required to be met. The approach to the targets in the electricity market has been to invest in renewable energy, mostly in the form of wind power. However, it is an intermittent production type where production depends on weather conditions and planning cannot be predetermined. As a result, the price of electricity has varied a lot in recent years and has also become very low, which causes profitability challenges for the electricity producers. One consequence is the closure of four nuclear reactors due to lack of profitability. This creates a more uncertain environment for the Swedish industry, which is dependent on both low electricity prices and reliable power supply. A way to counter this has been the “Energy Agreement”, that partly aims to promote the use of nuclear power for their total technical service life. The electrical system will change until 2030 in many ways, but how this will go is difficult to predict. By creating three different scenarios that reflect likely future changes, it has been possible to draw conclusions about what is necessary to change for the electricity system to be robust and competitive in the future. These scenarios consider wind power, active nuclear reactors, export opportunities and future electricity prices. These three scenarios have included identification of the most important parameters that need to be changed or considered by 2030. These parameters have been divided into price issues, delivery security and taxes with subsequent proposals. The most important items under these are to maintain the marginal cost based pricing model, create incentives for flexibility of electricity users and for manufacturers to provide the power grid with inertia. These require special focus to create a robust and flexible system, but remaining points are required as well to handle these issues. These points resulted in a framework that should form the basis for decision making. The framework should also be used in its entirety to analyze situations that may arise during the transition from today's market to the future's renewable electricity system. / Elmarknaden står inför stora förändringar de kommande åren, med stora produktionsanläggningar som måste ersättas och klimatmål som förväntas uppfyllas. Tillvägagångssättet har på den svenska elektricitetsmarknaden varit att satsa på förnybar energi, mestadels i form av vindkraft. Det är dock ett intermittent produktionsslag där produktionen är väderberoende och inte går att planera. Elpriset har till följd av detta varierat mycket under de senaste åren och blivit väldigt lågt, något som orsakar lönsamhetsproblem för producenterna. Ett resultat av detta är stängningen av fyra kärnreaktorer till följd av bristande lönsamhet, vilket skapar en oroligare situation för den svenska industrin som är beroende av både låga elpris och en tillförlitlig eltillförsel. Ett sätt att möta konflikten mellan producenternas olönsamhet och industrins krav är Energiöverenskommelsen, som delvis syftar till att göra kärnkraften med konkurrenskraftig. Elsystemet kommer att förändras till 2030 på många vis, men hur detta kommer gå till är svårt att förutsäga. Genom att skapa tre olika scenarion som speglar troliga framtida förändringar, har det gått att dra slutsatser om vad som är nödvändigt att förändra för att elsystemet ska vara robust och konkurrenskraftigt även i framtiden. Dessa scenarion tar hänsyn till vindkraftsutbyggnad, aktiva kärnreaktorer, exportmöjligheter och framtida elpris. Dessa tre scenarion har inburit identifiering av de viktigaste parametrar som måste förändras eller tas i beaktande till 2030. Dessa har delats upp i prisfrågor, leveranssäkerhet samt skatter med efterföljande förslag. De viktigaste punkterna under dessa är att behålla marginalprissättningen, skapa incitament för flexibilitet hos elanvändare och för producenter att tillhandahålla svängmassa. Dessa kräver särskilt fokus för att skapa ett robust och flexibelt system, men resterande punkter behövs för att hantera dessa frågor. Dessa punkter resulterade i ett ramverk som bör ligga till grund för beslutsprocesser. Ramverket bör också användas i sin helhet för att analysera situationer som kan uppstå under omställningen från dagens marknad till framtidens förnybara elsystem.

Sedan 2007 har ett forskningsprojekt på s.k. ”framtidens kärnkraft”, även kallat för fjärde generationens kärnkraft pågått i Sverige. För den här studien har jag dels antagit ett historiskt perspektiv för att undersöka hur detta projekt har utvecklats och förändrats över tiden. Jag har även använt mig av Faircloughs kritiska diskursanalys som metod och teori för att undersöka vilka argument som har använts (och på vilket sätt som dessa argument har förmedlats) när olika representanter bakom projektet försökte övertyga både Regeringskansliet 2012 och Energikommissionen 2015 om värdet av denna teknik. I den teknikhistoriska undersökningen uppdagades det att mellan åren 2007 - 2017 hade syftet och designen hos den föreslagna reaktorkonstruktionen förändrats avsevärt. Från början hade projektet handlat om att upprätta en forskningsanläggning i Sverige med både tillhörande reaktor, bränsletillverkningsanläggning och upparbetningsanläggning för produktion av plutonium som reaktorbränsle. Projektet fick däremot avslag från regeringen efter att både KVA och Vetenskapsrådet hade ställt sig kritiska till projektets utformning, ur både tekniska och samhällsekonomiska perspektiv. Därefter förändrades projektets utformning till att istället handla om kommersiell elproduktion för den kanadensiska gruvindustrin i Arktis. I den diskursanalytiska undersökningen visade det sig att framställningen av fjärde generationens kärnkraft i det analyserade materialet har vilat bakom en okritisk och positiv inställning till tekniken. Argumenten som har använts har för det mesta handlat om teknikens teoretiska möjligheter, men väldigt lite om realismen i dessa visioner. När åsikter eller värderingar har förekommit, har dessa nästan uteslutande formulerats som vedertagna sanningar, vilket både förstärker och upprätthåller aktörerna som auktoriteter på området. I analysen diskuterar jag även fem olika diskurser som jag identifierade i det analyserade materialet. Dessa diskurser menar jag verkar både reproducerande och omstrukturerande på den rådande diskursordningen, vars syfte har varit att försöka skapa ett förnyat intresse för fjärde generationens kärnkraft som tidigare gick under namnet ”bridreaktor”. / Since 2007 a Swedish research project have been attempting to develop “the next generation” of nuclear power plants, also called the fourth generation of nuclear power. In this study, I have partly adopted a historical perspective in order to investigate how this research project have developed and changed over time. I have also applied the methodology of Faricloughs critical discourse analysis in order to identify what kind of arguments and rhetoric’s that were used by some of the representatives of this project when they tried to convince the Swedish cabinet office in 2012 and the Swedish Energy commission in 2015 of the value of this technology. In the historical investigation, it was discovered that between the years of 2007 and 2017, the purpose and design of the proposed reactor had undergone several transformations and changes. At first, the leaders of the research project had been considering building a research facility in Sweden that would not only include a reactor, but also a fuel fabrication and reprocessing facility for production of plutonium fuel. However, the project was never approved by the Swedish government, after both KVA and Vetenskapsrådet had expressed criticism towards the project, due to both technical and socio-economic considerations. As a result, the direction of the project was transformed into commercial power production for the mining industry in the Canadian Arctic. In the discourse analysis, it became evident that the information and arguments that had been presented in the analysed material had been framed in a strictly positive and uncritical manner. The arguments that were portrayed had mostly addressed the theoretical possibilities of the technology, but very little about the realism of these visions. When opinions or values had been expressed, they had almost exclusively been phrased as inherent truths, which can contribute to both strengthening and upholding their status in society as authority figures. In the discourse analysis, I also discuss five different discourses which I have identified in the material that was analysed. These discourses were then concluded to be both reproducing and restructuring on the current order of Swedish nuclear and energy discourse.

No description available.

<p>The research presented in this dissertation investigates the influence of soil-structure<br> interaction on seismic isolation of nuclear reactor vessels using numerical simulations. This<br> research is motivated by the nuclear industry searching for viable solutions to standardize<br> the design of reactor vessels. Seismic isolation of reactor vessels is a potential solution as it<br> enables deployment of standardized reactor vessels irrespective of site seismic hazard<br> thereby saving time and cost by allowing large-scale factory fabrication of standard<br> modules and by eliminating the need for repeated approval of reactor vessel design. Seismic<br> isolation is also a technology that has matured from successful implementation in buildings<br> and bridges allowing easier transition to nuclear applications. Currently, the<br> implementation of component-level seismic isolation in nuclear industry is challenging due<br> to gaps in research and lack of specific guidelines.</p> <p><br></p> <p><br> In this research, the effectiveness and potential limitations of using conventional friction<br> pendulum bearings for component-level isolation are investigated based on conceptual<br> numerical models of seismically isolated reactor vessels at different nuclear power plant<br> sites subject to a variety of ground motions. The numerical modeling and analysis<br> approach presented in this research are checked using experimental data and results from<br> multiple numerical codes to ensure reliability of the obtained analysis results.</p> <p><br></p> <p><br> Within the scope of this study, it is found that slender vessels are particularly vulnerable<br> to rotational acceleration at the isolation interface. Rotational acceleration at the isolation<br> interface is caused by rotation at the foundation level of the containment building housing<br> the isolated reactor vessel and by excitation of higher horizontal translational modes of the<br> seismically isolated system. Rotation of the building foundation increases with decrease in<br> shear wave velocity of the soil surrounding the building foundation. When the containment<br> building is embedded below the soil surface, the effect of embedment on peak horizontal<br> acceleration of the isolated vessel depends on the amount of increase in shear wave velocity<br> at the foundation level of the building. When embedment does not result in any change in<br> shear wave velocity, it is found to have negligible impact on the acceleration response of the<br> isolated vessel.</p> <p><br></p> <p>  The optimum location to support a vessel for seismic isolation is found to be on a plane<br> passing through its center of mass. It minimizes horizontal acceleration in the isolated<br> vessel as well as the tendency of isolator to uplift. Isolator uplift and exceedence of<br> displacement capacity of the isolator during extreme events are possible drawbacks in using<br> seismic isolation technology since they produce impact forces due to uplift and<br> re-engagement of the isolator or due to collision between the isolated system and the moat<br> wall. If such cases are avoided, seismic isolation of reactor vessel could provide more than<br> 50% reduction in peak acceleration of vessel except for low-intensity motions that do not<br> engage the isolator.<br>  <br>  </p>

In collaboration with Westinghouse Electric AB this project aims to study the possibilities with using machine learning methods to predict fuel failure in a Boiling Water Reactors (BWRs). The main objective has been to create a dataset consisting of both empirical measurements and simulated samples from a physics model and evaluate different machine learning algorithms, that use these datasets to predict fuel defects. The simulated data is created using a physics model derived from the ANS-5.4 standard which allows for good control over specific parameter values. Three machine learning algorithms were deemed fit for this type of problem and used throughout the project: Random Forest (RF), K-Nearest Neighbor (KNN) and Neural Network (NN). Both classification and regression type problems have been assessed. All three methods showed good results for the classification problems, where the goal was to predict if there was a fuel failure or not. All models reached an accuracy above 97% and performed well, the RF model had the highest overall, with an accuracy of 98.2 %. However, the NN method made the fewest false negative predictions and can therefore be seen as the best model for this purpose. For the regression, problems with the aim of predicting escape rates, both the RF and KNN had similar promising results with very small errors overall. Yet, there is a slight increase in errors when predicting higher escape rates for both models. This is most likely due to the available data being of mostly low escape rates. The NN did not perform well with this problem, the predictions having large error for both low and high escape rates, a possible explanation is the lack of data. To improve the results, and create even better models, the empirical measurements need to contain more information such as defect location and fuel failure size, also an increase in the number of samples taken at fuel failure operation would be valuable.