Development of a Fiber-optic Noncontact Temperature Sensor for Measuring the Temperature of Cooled Secondary Water in a Nuclear Power Plant

Generally, a pH value of secondary water in a nuclear power plant should be estimated after sampling and cooling down. In this process, the measurement of temperature is very important because a pH value is varied according to the temperature of secondary water. In this study, a noncontact fiber-optic temperature sensor using a silver halide optical fiber is fabricated to measure the temperature of cooled secondary water. And we have measured an infrared radiation, which is transferred by a silver halide optical fiber from a heat source, using a thermopile sensor. The relationships between the temperature of a heat source and the output voltage of the fiber-optic temperature sensor according to the change of distance and angle are determined. The measurable temperature range of the fiber-optic temperature sensor is from 25 to 60℃. Based on the results of this study, a noncontact temperature sensor using a silver halide optical fiber can be developed for the temperature measurement of the pH sample in the secondary water system.