IRRADIATION BEHAVIOR OF DEVELOPED RADIATION-RESISTANCE OPTICAL-FIBERSAND OBSERVED OPTICAL RADIATION FROM THEIR SIO2 CORES UNDER REACTOR IRRADIATION

Two kinds of optical fibers were irradiated in a fission reactor, JMTR (Japan Materials Testing Reactor), up to a 1.55x10(19)n/cm(2) fast neu tron fluence and a 3.3x10(9)Gy ionizing dose at 370K. Optical transmis sion spectra were measured in the wavelength range of 450-1750nm, in-s itu. Growth of strong optical absorption bands were observed in the ra nge of wavelength shorter than 750nm. In the meantime, the fibers show ed good radiation-resistance in the range of wavelength longer than 75 0nm. Optical radiations were observed from SiO2 optical fibers under i rradiation. A major part of the observed optical radiations is thought to be composed of broad optical radiation in the whole wavelength ran ge studied in the present experiment. This broad optical radiation wil l be generated by the process of so-called Cerenkov radiation. Also, a sharp optical radiation peak was found at 1270nm on a F-doped fiber. This peak is thought to relate with doped Fluorine ions and ionizing g amma-ray irradiation.