High-dose temperature-dependent neutron irradiation effects on the optical transmission and dimensional stability of amorphous fused silica

Abstract

The primary concern for implementing amorphous fused silica (a-SiO2) fiber optic sensors in a nuclear environment is the radiation-induced attenuation (RIA) of the light signal due to the formation of radiation-induced color centers. In addition, Bragg grating sensors drift under irradiation due to radiation-induced compaction of the a-SiO2 structure. This work provides new data regarding RIA and radiation-induced compaction of a-SiO2 samples irradiated to a fast neutron fluence of 2.4 × 1021 n/cm2 at temperatures of 95, 298, and 688 °C. Results show that RIA may be approaching saturation for the range of photon energies evaluated in this paper and that the hydroxyl content has a significant impact on RIA when the irradiation temperature is increased to 688 °C. A model was developed for predicting radiation-induced compaction, and the resulting signal drift for Bragg grating sensors, as a function of neutron fluence and temperature.