An optical fiber sensing system is assessed for radiation performance. The optical fibers are irradiated with gamma radiation from a cobalt 60 source. The sensing system consists of a white light source, silicon detectors and multimode optical fibers. The optical system measures the chromaticity of the light in dominant wavelength derived from either a distimulus or tristimulus measurement. Both measurement systems are generic and can operate with up to eight modulating sensors simultaneously and are designed to form part of existing monitoring or control system. All components are commercially available and the optical fiber system is undergoing trails in the nuclear, chemical and electrical power distribution industries.