Modular Small Reactor Main Pump Takeover Stress Analysis And Structure Optimization

Nuclear power plant is an important discovery in human history. Nuclear energy hasbeen considered as the ideal clean green energy resource, which is benefit to meet theenergy growing needs of economic and social development, energy supply and security. Itis also plays an important role in achieving power structure optimization, improving ournational strength and sustainable development ability. But, due to the seriousness of thedestructive effect of nuclear power plant accident, nuclear security and peaceful useof nuclear energy have become important topics. So, we must ensure thesustained and sound development of nuclear energy.In a lot of accidents, nuclear problems caused by increasing number ofreactor pressure vessel accident are showing an upward trend. Main pump nozzle is theweak link and dangerous position of reactor pressure vessel, is the important area whenevaluating its safety. So, analyzing the axial stress distribution of joint area between themain pump nozzle and reactor pressure vessel can improve the reactor pressure vessel’ssafety.The main pump nozzle is the connection of reactor pressure vessel and main pump, itsfunction is transporting fluid and thermal energy and become a whole and complete unionwithin. The opening between reactor pressure vessel and main pump has decreasereactor pressure vessel walls’ intense and will also happen stress concentration, which thestress value is more than doubled to the membranes stress. The loads applied on the mainpump nozzle of nuclear reactor pressure vessel are weight, pressure, thermalexpansion, and earthquake and pipe loadings during the running of the nuclear powerstation, which make the axial stress distribution of opening areas very complex. Analyzingthe stress distribution of main pump nozzle and evaluating its safety become more andmore important.Currently, stress numerical simulation is widely used in civil construction main pumpnozzle safety and design, and having made good practical effect, but its application is stillin its infancy in the nuclear power plant. This study analysis the mechanical stress of mainpump nozzle, which under the first kind of condition. A model closed to real main pumpnozzle established by the ANSYS in nuclear power plant. Using the “path operation” makethe stress results linearize, evaluating the safety of main pump nozzle by the stresslinearization results base on RCC-M. In the last, comparing thenumerical simulation results with Workbench’s result, Numerical simulation results showthat the stress linearization results and evaluate conclusion has a high accuracy. To improvemain pump nozzle safety and economy, using the “Design Explore” model make the modelsize become small, which can save raw processed materials, decrease the equivalent stressand reduce the stress concentration. By this method, nuclear safeties researchers can getmore reliable main pump nozzle protection design concept and assessment ways to reducethe risk of stress destroy, ensuring nuclear power plant safety.