Research On Nuclear Waste Barrel Temperature Field Monitoring Technology Based On RDTS

With the rapid development of China's nuclear energy industry,a large amount of nuclear waste is urgently needed for disposal.In the process of nuclear waste disposal,temporary storage of nuclear waste for a long time is an important part.After the impact of earthquakes,landslides and other geological disasters on the temporary storage of nuclear waste in the southwest of China,the redistribution of the stress field may cause the nuclear waste barrels stored therein to be deformed or even damaged.Therefore,the nuclear waste barrels need to be Safety monitoring.Damage to the nuclear waste barrel will cause nuclear waste to leak,which in turn will increase the ambient temperature at the leakage point.Therefore,it is of great significance to carry out the monitoring of the temperature field of the nuclear waste barrels in the nuclear waste temporary storage to provide basic data for the safety management of the nuclear waste storage.Distributed optical fiber sensing technology is an emerging advanced sensing technology with good resistance to radiation interference and distributed measurement characteristics.Among them,the Raman distributed optical fiber temperature sensor(RDTS)is the most widely used.It uses a lower-cost optical fiber as a sensing unit and uses the temperature-sensing characteristics of Raman scattering of light in the optical fiber to measure the temperature.It is suitable for harsh environments and has The application of monitoring requirements in a larger space.With the support of the National Natural Science Foundation of China(41704130)project and the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Free Exploration Project(SKLGP2014Z013),this paper addresses the need for temperature field monitoring of nuclear waste barrels in the nuclear waste temporary storage,combined with distributed optical fiber The advantages of sensing,this paper has carried out the research of RDTS-based nuclear waste barrel temperature field monitoring technology,the main research contents are as follows:(1)The RDTS nuclear waste barrel temperature field monitoring experimental device was built.Aiming at the requirements of temperature measurement accuracy and abnormal temperature location in the temperature field monitoring of nuclear waste barrels in the nuclear waste temporary storage,according to the RDTS temperature measurement principle and the selected temperature demodulation method,the temperature of nuclear waste barrels based on RDTS is studied and established Field monitoring experimental device is used to improve the accuracy of temperature measurement and the verification of the effectiveness of temperature anomaly location methods.(2)Research on RDTS noise reduction method.Aiming at the requirements of temperature measurement accuracy in the temperature field monitoring of the nuclear waste barrels in the nuclear waste temporary storage,the source of noise in the RDTS system is analyzed,the RDTS noise reduction method is studied,and the dichotomize singular value decomposition and the one-dimensional Median filtering is used for RDTS noise reduction.(3)Research on the method of abnormal temperature location of nuclear waste barrel temporary storage.Aiming at the requirements of abnormal temperature location in the monitoring of the temperature field of nuclear waste barrels in the temporary storage of nuclear waste,a research on the method of abnormal location of nuclear waste barrel temperature based on RDTS was carried out,and an abnormal location of nuclear waste barrel temperature based on principal component analysis.(4)RDTS system software design.In order to facilitate the use of the noise reduction and positioning methods proposed in this paper,the software system design based on the mixed programming of Qt and MATLAB was studied to complete the temperature measurement and temperature abnormal location.The main innovations of this article:(1)The RDTS signal noise reduction method based on dichotomize singular value decomposition is proposed,which can effectively reduce the deviation of the RDTS temperature measurement result caused by noise,and has a better effect than the wavelet transform method commonly used for RDTS noise reduction.(2)A method for locating nuclear waste barrel temperature anomalies based on principal component analysis is proposed.The features of nuclear waste barrel temperature anomaly monitoring data are extracted by principal component analysis and matched with the characteristics of temperature anomaly data with known locations to achieve Abnormal temperature location.Experimental results show that this method can accurately locate the abnormal temperature location.