Assembly And Removal Technology Instrumentation Core Nozzle Closure And Sealing Test In EPR Nuclear Power

With the continuous innovation and improvement of the construction technology of nuclear power plants,the conventional method of sealing cannot meet the sealing requirement of the key parts of the nuclear power stations.The sealing function between the instrumentation and the adapter determines the safety of a nuclear power plant for its long term operation,and it plays a more and more important role in the 3^rd-generation nuclear power plants.This thesis focuses on the instrumentation core nozzle closurebelonging to the category of EPR?European pressurized water reactor?nuclear power instrumentation core system,which is quite different from the CPR1000?China Improved Pressurized Water Reactor?nuclear power instrumentation core system.The difference is that the EPR nuclear reactor instrumentation core is located on the top of the nuclear pressure vessel and that it is connected by 16 groups of nozzle closures and headers.However,CPR1000 instrumentation core is located at the bottom of the nuclear pressure vessel and it is connected by 50groups of guide tubes and Neutron flux tubes.Due to changes in the structure of the instrumentation core system,there are great differences in construction methods and control measures,and the position of the instrumentation core is moved from the bottom of the nuclear pressure vessel to the top of the nuclear pressure vessel.It not only increases the construction workload of the nuclear pressure vessel,but also increases the risk of equipment construction.Therefore,personnel need to be more cautious in the construction process,so that the entire instrumentation core system highlights its sophisticated,complex and high-risk characteristics during the construction process.This thesis introduces the structures,functions and acceptancecriteria of instrumentation core nozzle closure into EPR nuclear power plant.This thesis expounds the technology,sealing test and equipment,and proposes the risk analysis and countermeasures for the assembly and removal technology of instrumentation core nozzle closure,combined with the construction experiences in Taishan Phase I.The operators can quickly connect and dismantle with the external instrumentation nozzle according to his rational design structure and assembly and removal technology to achieve the purpose of sealing.dueing to the pressure boundary of the primary circuit of the nuclear power station where the nozzle closure is located.In order to save working time for maintenance personnel during follow-up overhaul,it effectively reduces the radiation absorbed dose when maintenance personnel perform the work,and reduces the radiation damage to maintenance personnel to some extent.In order to guide the nozzle closure assembly and removal as wellas verify the tightness scientifically and effectively,this thesis analyzes the effectiveness of three aspects of component cleanliness and dimensional state,and proposes the countermeasures in the process of assembly and removal technology,as well as the experimental verification of the effectiveness of vacuum test sealing inspection.Finally,the relevant conclusions are drawn through the statistics and analysis of the test phase,test positions,spring compressing values and permissible raise pressure data.No leakage occurred in the cold and hot functional test of the unit 1 and the cold functional test of the unit 2 of Taishan Nuclear Power Plant,which verifies that assembly and removal technology is feasible and correct during Taishan nuclear power plant construction.At present,only three nuclear power plants in the world adoptEPR nuclear power technology,which is olkiluoto 3rd nuclear power plant in Finland,Frammonville 3rd nuclear power plant in France and Taishan nuclear power plant in China.The experiences and methods of Taishan nuclear power plant are used for reference in the operation and commissioning of the nuclear power plants in the first two nuclear power plants.