# Material Science

 The flashcards below were created by user ereim on FreezingBlue Flashcards. Experienced by a thick-walled vessel due to the combined stresses from a rapid temperature and/or pressure change. Non-uniform temperature distribution and subsequent differential expansion and contraction are the causes of the stresses involved Pressurized thermal shock Identify the three components that will set limits on the heatup and cooldown rates FlangesReactor Vessel HeadReactor Vessel Identify the basis for determining heatup and cooldown rate limits Failure Life - impact on the life of the plant prior to fatigue becoming a likely failure madeLimiting thermal stress - created when the large components of the reactor vessel are heated and cooled Given a minimum pressure and temperature (MPT) graph, determine the limiting temperature or pressure. Minimum Bolt up 70oF Given a minimum pressure and temperature graph determine the minimum temperature allowed to tension the vessel head and state basis 80oFMost limiting temperature based on most limiting component State the action typically taken upon discovering the heatup or cooldown rate has been exceeded. No immediate hazard, only requires an assessment of the impact on the future fatigue life of the plant State the reason for using soaktimes So that heating can be carefully controlled. In this manner thermal stresses are minimized State when soak times become significant When a limiting component is at room temperature or below and very close to its RTNDT temperature limitations Identify two stresses that are the result of thermal shock to plant materials Tensile stressCompressive stress State the two causes of thermal stress Non-uniform heating of a uniform metalUniform heating of a non-uniform material Describe why thermal shock is a major concern in reactor system when rapidly heating or cooling a thick walled vessel Concern due to the magnitude of the stresses involved with rapid heating or cooling List three operational limits that are specifically intended to reduce the severity of the thermal shock Heatup and Cooldown rate limitsTemperature limits for placing systems into operationSpecific temperatures for specific pressures for system operations STATE how the pressure in a closed system affects the severity of thermal shock Pressure raises the severity due to additive effect of thermal and pressure tensile stresses List the four plant transients that have the greatest potential for causing thermal shock Excessive heatup and cooldownPlant ScramsPlant pressure excursions outside of normal pressure bandsLoss of coolant accident (LOCA) State the three locations of primary concern for thermal shock in a reaction system Reactor VesselReactor Vessel HeadReactor Vessel FlangePressurizerCVCSPressurizer Spray Line Authorereim ID34491 Card SetMaterial Science DescriptionChapter5 Thermal Shock Updated2010-09-14T14:09:05Z Show Answers