Nuclear Power Plant Prestressed Concrete Containment Vessel Structure Monitoring Based On Multi-scale Fiber Optic Sensors

Nuclear power is a kind of clean and efficient energy.And it provides a method for the energy crisis.However,once the nuclear power plant breaks down,environment pollution,heavy losses of lives and property will be caused.As the last barrier of nuclear reactor,prestressed concrete containment vessel(PCCV)plays an important role in the daily operation.Moreover,containment vessel will prevent the hit of plane and missile or the increasing pressure.Therefore,the structure health monitoring is significant to the PCCV.The PCCV consists of outer prestressed concrete structure and intimal steel liner.In order to testify the integrate property of PCCV,integrated leakage rate test(ILRT)was conducted every ten years.During the ILRT,the maximum inner pressure was 1.15 times of design pressure in order to testify the tightness of PCCV and inspect the surface defect.Structure health monitoring(SHM)is a new branch of science.And it is widely used in all kinds of civil engineer structure.Among different sensors in the SHM,fiber optic sensors are very popular,such as Fiber Bragg Grating(FBG),white light interferometry(WLI)and Brillouin Optical Time Domain Analysis(BOTDA).In this paper,these three kinds of fiber optic sensors were used in monitoring the PCCV structure during the ILRT.Comparing the inner pressure variation trend with monitoring strain during ILRT,the condition of PCCV material could be known.Besides,the finite element method model was built to calculate the strain variation trend with increasing inner pressure.Fortunately,the calculation results can be verified by monitoring results.And then the locations of high value strain could be gotten and provide much information for sensor placement.It can be concluded that using three kinds of fiber optic sensors to monitor the PCCV structure is feasible.Besides,finite element method will provide suggestion for sensor placement.