Study Of Several Key Issues In Reactor Pressure Vessel

As a kind of clean,reliable and secure energy,nuclear power has absolutely advantage compared to other energy,Whether from the optimization of the energy layout,adjusting the energy structure and protecting the ecological environment,promoting energy security perspective with the development of world economic and technology and the trend of shortage of energy and resource.On the other hand,the development of nuclear power not only led to the development of the nuclear industry also promoted the development of the equipment manufacturing industry and other related industries.The level of development of nuclear power also represents the level of China's peaceful use of nuclear energy levels and technological innovation.Although the proportion of total generating capacity of China's nuclear power is not high,but the scale of nuclear power in the planning and construction of the world's largest.In china,Localization of nuclear equipment and technology level was not high,the important equipment and technology need to be improved further,Otherwise it would affect the formation of the overall strength of China's nuclear power industry,to restricting its standardization,industrialization,large-scale development.So the United States and France's technology was introduced.Reactor pressure vessel as one of the key equipment of nuclear power industry,also the one of the key pressure equipment which was the most difficult to design and manufacture,was located in the center of the reactor building as RCC-M nuclear safety equipment,to be the core equipment in the loop of nuclear power station,and withstand the heat and pressure of the primary coolant,but also by a highly radioactive reactor main body.So the reliability and security is an important indicator of the design.Research in this paper mainly about the process of the reactor pressure vessel's opening and closing and the stress-strain state of the pressure vessel under the design pressure and temperature and the equipment bolt tension machine.Research made in this paper was mainly about the material,structure,design criteria and how to start and shut the process of nuclear reactor.The bolt stretching machine was used in opening and shutting the lid of the reactor pressure vessel during hydrostatic test of the reactor pressure vessel,reactor installation,reactor openings overhaul,reactor refueling.During openings maintenance and reactor refueling,the opening and shutting operations of the reactor pressure vessel was in the critical path.So efficiency of the bolt stretching was important to the economic benefits of nuclear power plants.here were integral style bolt stretching(MSTM)and score style bolt stretching(SSTM).Compared to SSTM,MSTM had the advantage as follow:(1)More efficient,and saving refueling time.(2)Reducing using of hanging ring and do not affect the work of other parallel.(3)The bolt tension and forced uniformly.(4)No residual torque bolts and the residual stress uniformity.(5)Reduce the bending of the cover flange and the main bolt.(6)Operator got small doses of radiation,low labor intensity.According to China's nuclear power planning,in 2020,China's nuclear power installed capacity would reach to 60 million kW,at least 50 new million-kilowatt nuclear power plant would be built,and it was expected that the integral bolt tension machine needed would be more than 25 sets.Which would cost more than 20 million yuan,and the output of the 25 sets bolt tension machine would be more than 500 million yuan,and maintenance,technical support,would also create more profits.MSTM not only could be used in the second-generation nuclear power plants,could also be used in the operation of three generations of nuclear power plants and other type of reactor' s opening and shutting.Domestic market of Integral bolt tension machine was currently monopolized by a small number of foreign manufacturers.Researching on bolt stretching and mastering the technology of bolt stretching could break the monopoly of technology and products,which is of great significance for nuclear power facilities and was conducive to the sustainable development of China's nuclear power industry.Research and analysis of major subsystems of the overall bolt tension machine,stretch ring,car,hydraulic system and detection system made the plan of overall bolt tension localization program,and pointed out the key technology and problem faced in localization process and also find out the corresponding strategies and methods.The research on strength theory and elastomer stress-strain showed stress analysis methods of the reactor pressure vessel included analytical method,numerical methods and experimental method,meanwhile showed finite element method in numerical methods was a kind of error controllable and effective method in stress analysis and strength design of the reactor pressure vesse.Based on the research on the most advanced third generation AP1000 nuclear power characteristics and pressure vessel structure,materials,designing requirements,and working conditions,three-dimensional digital model of the AP1000 pressure vessel was built and processing simplify and then applied pressure and temperature loads,formed an effective finite element model.This model was meshed applying of the second-order tetrahedral elements through the h-adaptive method,and then stress-strain analysis was made applying three-dimensional finite element technology,finally the maximum stress point and the maximum strain would be found.Research on the result of the finite element analysis showed AP1000 pressure vessel met the strength requirements of the RCC-M in designing conditions.