Key Technology Of On-line Monitoring System For O-ring Sealing

With the demands of both resource utilization efficiency and environmental protection,developing clean energy and promoting energy efficiency are the important directions in the field of energy technology.The development and application of nuclear power technology plays an important role in China’s medium and long-term energy strategy.Nuclear reactor pressure vessel is a major equipment for boundary protection,so its sealing performance is directly related to the normal startup and long-term safe and stable operation of nuclear power facilities.The original periodic leakage inspection method of O-ring’s failure assessment and all the original regular replacement maintenance mode of O-ring are far from meeting the development demand and economic demand of nuclear power technology.Therefore,traditional sealing failure assessment needs to be replaced,and it has potential social and economic prospects to introduce realtime online monitoring technology of sealing state to meet the demand of nuclear power development.For the particularity of the O-ring in the field of nuclear power,The problem of Oring’s monitoring the sealing state is transformed into the problem of optical measurement of the clearance of its installation structure with the advantages of optical fiber sensing measurement such as high sensitivity,high precision,anti-electromagnetic interference and remote control.A new idea and method of monitoring of O-ring’s sealing state is proposed.This paper proceeds from the overall scheme of optical measurement,signal demodulation,high temperature resistant optical fiber probe design and real-time demodulation system development.The following research work has been carried out.(1)In view of optical measurement of the gap of O-ring structure,the overall scheme of frequency-sweeping interference is proposed.Combined with the Fourier demodulation method of interference signal,the correlation between signal contrast and frequency detection during signal demodulation is analyzed and the special requirement for fiber probe structure design and optimization is proposed.The resolution of Fourier demodulation algorithm is analyzed.(2)Aimed at the design and development of the optical fiber probe,the complete optical simulation system from the optical fiber probe to the beam energy detection is established,with experiment system set up and the structure optimization design of the fiber probe completed.Combined with the demand of high temperature resistance of optical fiber probe,a coaxial armored structure with mechanical strength and high temperature is proposed.The installation structure of the probe is designed and the temperature compensation method of differential installation of double probes is proposed.(3)In view of high-precision demodulation for interference signals,the experimental system for the gap of O-ring structure is built based on the principle of optical sweep interferometry.The real-time gap demodulation software is developed by use of Lab VIEW Software Platform.The room temperature experiments’ results verify the accuracy and stability of the measurement system.The experiments’ results in high temperature environment verify the high temperature resistance of optical fiber probes.