In the present paper, we have analyzed deeply and parametrically both the penalties of performance of single mode optical fiber cables employed in thernmo-irradiated fields in nuclear projects environments and space communication systems. The radiation effects as well as the thermal effects are modeled and investigated over the practical ranges of interest. Four dependent effects { spectral losses, pulse spreading, fiber bandwidth, and transmitted bit rate} as well as the sensitivities of variations of the causes are studied through the four defined sensitivities ( bit rate-spectral losses, bit rate-bandwidth, bit rate-temperature, bit rate-dose]. Severe reduction effects of both the thermal field and the irradiation field are assured and concluded.