Development of a fiber-optic remote temperature sensor to monitor water temperature in a spent nuclear fuel pool

Abstract

In this study, a fiber-optic remote temperature sensor (FRTS) for real-time temperature measurements in a spent nuclear fuel pool is developed. The proposed FRTS consists of a fiber-optic temperature-sensing probe and an optical time-domain reflectometer (OTDR). The probe of an FRTS consists of silicone oil, a fiber channel (FC) terminator, a single-mode optical fiber, and a copper metal cap. Silicone oil is employed as a temperature-sensing material owing to its temperature-dependent refractive index. The optical powers of the reflected light signals (Fresnel reflection), which are generated at the interface between the silicone oil and the core of a single-mode optical fiber in the distal end of the sensing probe, are measured. The temperature of the water was measured in 5 ℃ increments ranging from 10 to 70 ℃, using a fabricated FRTS and an OTDR. The proposed FRTS could be used to effectively monitor the water temperature of a spent nuclear fuel pool (SNFP) at a nuclear power plant (NPP). © 2019, The Optical Society of Japan.