In the present paper, the penalties of performance of single mode optical fiber cables employed in thermo-irradiated fields in nuclear projects environments and space communication systems have been analyzed deeply and parametrically. Irradiation effects as well as the thermal effects are modeled based on experimental measurements, the investigated over the practical ranges of interest. Spectral losses as well as total chromatic dispersion are considered for thermal-irradiation dependences. Four dependent effects {spectral losses, pulse spreading, fiber bandwidth, and transmitted bit rate} are then investigated. Severe reduction effects of both thermal field and irradiation field are assured and concluded. Comparison between the present case and the irradiation-free case at room temperature is made. Three cases of special impact at three special windows are studied namely: dispersion-free, losses-free (minimum), and OH-losses-free. It is found that the maximum available bit rate is 5.89 Tbit/sec at optical wavelength l=1.59 mm at OH-free, no marginal losses and dose-free case.