Research On Bearing Capacity Testing Machine For Steel Containment Ellipsoidal Heads Of Nuclear Power Plants

Currently,with the rapid development of world economy,the world's energy supply shortage has become increasingly prominent.As more attention being paid on environmental protection,climate change,greenhouse effect,etc.,nuclear power has become the focus of energy development in the world.In our country,there are many problems in nuclear power industry,such as:low technological level,low equipment independence level,low economical efficiency.In order to significantly improve economical efficiency and security,and achieve sustainable development of nuclear power,through the importation,digestion,absorption of generation III nuclear power technology,our country is developing safer and more efficient generation III reactors,like CAP 1400,CAP 1700 with independent intellectual property rights.Large-scale advanced PWR,such as AP1000,CAP 1400,adopts passive safety system.One of its notable features is the inner freestanding cylindrical steel containment vessel.The steel containment vessel not only provides protection against the uncontrolled release of radioactive fission materials to the environment,but also is an effective heat conductor,which can rapidly reduce containment temperature and pressure through exchanging heat under accident conditions.Therefore,a complete study of the steel containment behavior under accidents is extremely important.The bearing capacity of steel containment vessel is an important indicator of the performance of the containment structure,however,in our country the experimental study in this area has been relatively scarce.Supported by the program of state key science and technology projects,bearing capacity test for CAP 1400 steel containment ellipsoidal heads(Project No.:ZB01K10W09),we carried out a study of the bearing capacity testing vessel and water proof technology for strain measurement for nuclear power plants steel containment ellipsoidal heads.The main research work of this thesis can be described as the following four parts:(1)Based on the requirements of bearing capacity test of nuclear power plant containment steel ellipsoidal heads,specific requirements of test vessel function,structure and water proof technology for strain measurement were proposed.Then the technical parameters were determined:(1)design pressure;(2)design temperature,material parameters,testing medium,etc.(2)The structural design of the test vessel was carried out,and then two kinds of finite element models were established:the model of vessel base and axisymmetric model.Apparatus structure was assessed by stress analysis,strength assessment and buckling assessment.(3)Considering the water proof technology of large strain measurement in the test under hydraulic pressure,a study was carried out.Specifically,the suitable protective agent was selected by experimental study,and compensation method of pressure and temperature was optimally designed.And then water proof process of strain measurement system was improved.The feasibility and effectiveness of the water proof technology of large strain measurement under hydraulic pressure was well verified by water proof performance test.(4)Through the actual test,we analyzed the effect of water proof method of strain measurement,the stress intensity of key positions of test vessel,the blasting results of ellipsoidal heads,therefore,the reliability of the test vessel was verified.