Gamma-Ray Irradiation Effect on Loss Increase of Single Mode Optical Fibers, (II)

Estimation of Loss Increase due to Long Term Irradiation

Abstract

In order to examine the reliability of optical fiber systems in nuclear power plants, we estimated the induced losses of pure silica core and GeO₂ added core single mode optical fibers (Si-SMF and Ge-SMF) exposed over a long period to low dose rate γ-rays (less than 100 R/h, 40 yr). Also γ-ray induced losses under a high dose rate and high temperature condition such as 106 R/h and 200°C were estimated in view of an accident.
In both cases, the induced losses were concluded to depend mainly on total dose from the results of low dose rate irradiation experiments and a study on temperature dependences of induced losses
It was ascertained from the estimation that the Si-SMF had less radiation sensitivity than the Ge-SMF in the radiation environment of nuclear power plants The induced loss of the Si-SMF exposed for 40 yr to 1 R/h γ-rays was estimated to be about 2 dB/km and almost five times lower than that of the Ge-SMF.