In-situ mitigation of radiation-induced attenuation in optical fiber used for sensing at nuclear facilities

The ionizing radiation environment in a nuclear reactor containment building or geological waste repository may result in saturation of the radiation-induced attenuation (RIA) in fiber optic cables. Room temperature irradiations to Mrad doses were carried out to quantify RIA recovery at both ambient and elevated temperatures. Additional experiments sought to establish a reduction in RIA beyond recovery obtained by thermal annealing alone by incrementally increasing injected light power from 1 μW to 12 μW over varying time intervals. Results indicate that total possible signal recovery under such conditions is ∼70% and is dominated by thermal annealing of short-lived color centers with supplemental low-intensity (μW) photobleaching providing little to no additional benefit.