Development and Studies on FBG Temperature Sensor for Applications in Nuclear Fuel Cycle Facilities

Abstract

This paper presents the novel results on fiber Bragg grating temperature sensor deployment in high radiation and hazardous chemical environment of nuclear fuel recycle facility. The sensor is developed using thermally regenerated grating obtained from the thermal annealing of seed type-I grating inscribed in telecommunication fiber. The studies on the operating life time and average sensitivity of regenerated grating were carried out upto 900 °C. For the remaining reflectivity of $\sim 5$ % at 900 °C, the predicted lifetime of the grating was around 4 year. The radiation hardness of the packaged FBG sensor was tested in high radiation environment upto 1 MGy. Bragg wavelength shift of $\sim 35$ pm was observed after 1 MGy accumulated gamma radiation dose. Developed and characterized FBG sensor was finally deployed for temperature monitoring of nuclear fuel recycling chamber. Reliable and accurate temperature measurement helped to precisely control the process and to avoid the spill over of uranium, plutonium nitrate solution in the microwave heated process chamber.