Passive optical fiber sensor system for water level monitoring with implementation of human-machine interface module

In this paper, we demonstrate a remote passive optical fiber sensor system based on space division multiplexing for water level monitoring targeting to extreme environments, such as a spent fuel pool in nuclear power plant. The proposed system is evaluated under laboratory conditions to demonstrate its feasibility for future nuclear safety instrumentation applications. It employs a broadband light source as a seed light and a 1 × 4 optical splitter for multiplexing/demultiplexing multiple optical fiber sensors. Four sensors are vertically installed in a water pool at predefined heights. By measuring the reflected optical power from each sensor with an optical receiver, the discrete water level state corresponding to the predefined sensor positions can be determined in real-time. To mitigate the effect of Rayleigh backscattering in remote sensing, a simple dual-path configuration is introduced. Experimental results show that the proposed system can monitor water levels over a distance of approximately 19 km, limited by the performance of the detector. On the other hand, providing intuitive and real-time information for water level monitoring to operators remains a significant challenge. To address this issue, a human-machine interface (HMI) module is also implemented. By providing real-time information on the discrete water level states and system status through the HMI display, it enables operators to intuitively monitor the current water level status, as well as perform trend analysis and abnormal condition detection.