Pseudo-plane strain compression tests are carried out on rolled plate Zircaloy-2 using different combinations of loaded and constrained sample directions relative to the plate principal directions. Lattice strains are measured for 17 out of 18 possible measureable sample directions. The inability to obtain true plane strain led to little effect of the compression rig on deformation during elastic loading; however noticeable differences are seen when compared to similar uniaxial data for Zircaloy-2 in the plastic region. Work hardening increased with increased constraint and was affected by the configuration of loaded and constrained sample directions. Constraint showed significant effects on twinning when twinning was present. For the RD loaded cases the initiation of twinning occurs at -318 MPa for the RD/ND case (RD loaded, ND constrained direction) and -420 MPa for the RD/TD case. Intensity profiles of the (0002) and {101 ̅ 0} indicate that more twinning occurs in the RD/TD case than the RD/ND case. For TD/YD an amplification of twinning was seen in the TD/RD when compared to the TD/ND. This is indicated both by texture results as well as the intensity profiles of the (0002) and {101 ̅ 0}. Using the experimental data an elastic-plastic self-consistent (EPSC) code was used to probe the micromechanical processes that are occurring when the compression rig is operated. The experimental data was used further to constrain the hardening parameters of the EPSC code using an inverse approach. The EPSC code was able to capture the relative activity of the twinning characteristics found by the experimental data but unable to truly capture the evolution of the (0002) lattice strains when twinning occurs. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2014-01-13 11:24:21.692

The fuel cladding is an essential component in the defence-in-depth strategy for nuclear safety. Its integrity and durability are therefore critical for maintaining acceptable safety conditions. However, the integrity of the cladding can be compromised during normal operation due to corrosion and hydriding. To ensure a sufficient level of safety, design and safety criteria have been established to limit oxidation and hydriding. EDF has various multiphysics software tools at its disposal to ensure that these criteria are met. One such tool, CYRANO3, uses oxide thickness measurements from the beginning of the French nuclear industry to model corrosion and hydriding. This study aims to improve CYRANO3 by expanding its validation database and improving its models. The first part of the study focuses on improving the CYRANO3 database by providing a more comprehensive understanding of normal corrosion in a pressurized water reactor, allowing the models to be recalibrated to better represent actual corrosion behaviour.  In the second part, a deeper analysis is conducted to improve the models and increase knowledge of the parameters that influence corrosion. This analysis highlights the significance of temperature and power as input parameters, which will affect the accuracy of CYRANO3 results. Additionally, this study has identified areas for further improvement, including modifications to the implemented corrosion models and a better understanding of the assumptions made about input data. / Brunnkapslingen utgör den första barriären i principen för försvarsdjup. Därför är dess integritet och hållbarhet en prioritet för att upprätthålla acceptabla säkerhetsförhållanden. Integriteten hos brunnskapslingen kan hotas under normal drift genom korrosion och hydridisering. Därför har design- och säkerhetskriterier fastställts för att säkerställa en tillfredsställande säkerhetsnivå genom att begränsa oxidation och hydridisering. EDF har flera multiphysics-program tillgängliga för att säkerställa att dessa kriterier uppfylls. CYRANO3, det program som används i denna studie, baserar sina korrosion- och hydridiseringmodeller på mätningar av oxidthickness som har registrerats sedan starten av den franska kärnkraftsindustrin. Kvaliteten och sanningshalten hos dessa modeller måste testas och uppdateras med den nya erfarenheten av den franska flottan. Denna studie handlar om att förbättra CYRANO3 genom att utöka dess valideringsdatabas och förbättra dess modeller. I den första delen förbättrar förbättringen av CYRANO3-databasen en mer fullständig bild av normal korrosion i en tryckvattenreaktor. Denna utökning gör att modellerna kan recalibreras för att mer exakt återspegla den faktiska korrosionsbeteendet. I den andra delen görs en djupare analys för att förbättra modellerna och öka kunskapen om de parametrar som påverkar korrosionen. Denna analys visar på vikten av temperaturen och kraften som indataparametrar, vilka kommer att definiera kvaliteten på CYRANO3:s resultat. Dessutom har denna studie öppnat upp för nya områden för förbättring, bland annat genom korrigeringar av de implementerade korrosionsmodellerna och en bättre kunskap om antagandena om indatadatan.

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