There is an increasing desire to conduct autonomous inspection of nuclear sites using robots. However, the presence of gamma radiation in nuclear sites induces degradation in vision sensors. In this paper, the effects of gamma radiation on a robot vision sensor (CMOS camera) used for radiological inspection is examined. The analyses have been carried out for two types of images at different dose rates: a) dark images b) illuminated images. In this work, dark images and chessboard images under illumination are analysed using various evaluation metrics to evaluate the effect of gamma radiation on CMOS Integrated Circuit (IC) and electronic circuitry of the sensor. Experimental results manifest significant changes in electrical properties like the generation of radiation-induced photo signal in sensing circuitry and radiation-induced noise affecting the visual odometry of the robot. System-level degradation for gamma dose rates upto 3 Gy/min intensifies, making data from the imaging sensor unreliable for the visual odometry. However, images captured for gamma dose rate upto 3 Gy/min can be used for surveillance purpose.