Thresholds for radiation sensitivity of polymers in combined radiation-thermal environments

A highly conservative value for all common polymers is 1 kGy (0.1 Mrad) (high certainty of being inconsequential). 10 to 20 kGy (< 2 Mrad) is an acceptable threshold margin if polymer degradation is reasonably well-understood. Material performance subject to the upper threshold should be corroborated by well-understood thermal long-term ageing processes to confirm residual margin. With radiation dose exposure being less than such a threshold, the overall long-term degradation will be dominated by thermal and other processes. Radiation thresholds can guide improved material qualification testing, condition monitoring emphasis and extended use considerations.