The behavior of erbium doped fiber amplifiers (EDFA) in a master oscillator power amplifier configuration was characterized, for the first time, in-situ using a 60 Co γ-ray source. The results indicate that power degradation and photo-anneal recovery processes simultaneously exist. A fiber optimized for efficiency also provides a radiation harder EDFA with reduced power degradation after a 10 kRad (100 Gy) exposure.