Experimental research on temperature field construction of nuclear waste barrel based on RDTS with improved spatial resolution

In this paper, a 3D temperature field construction method based on Raman Distributed Temperature Sensor (RDTS) with improved spatial resolution is proposed to monitor the side surface temperature of Nuclear Waste Barrel (NWB). This method includes two aspects: the spatial resolution enhancement of RDTS and the signal dimension conversion. Firstly, the spatial resolution improvement method combining Fully-Connected Neural Network (FCNN) and Total Variation Deconvolution (TVD) is used to improve the spatial resolution of RDTS from 1.6 m to 0.4 m. Then, the one-dimensional temperature signal is converted into 2D temperature field by matrix laying method. Finally, by establishing the coordinate system of the NWB, the 2D temperature field can be converted into a 3D one. The experimental results of the simulation device showed that when the circular thermal area with diameter of 0.4 m, 0.6 m and 0.8 m appeared on the side surface of NWB, the temperature accuracy of the temperature field image constructed by this method can reach 80.91 %, 72.09 % and 85.97 % respectively, and the shape was accurate. The method proposed in this paper can accurately present the surface temperature field of NWB and provide technical support for the safe operation of the nuclear waste disposal repository during its life cycle.