Radiation testing of optical fibers for a hot-cell photometer

In-line photometers are a possible method of monitoring separation processes in future nuclear fuel reprocessing facilities. Fiber optics will be used to transit light to the photometer cell and return the attenuated intensity to a photodetector, allowing removal of all the electronics from high radiation zones. In support of photometer development, commercially available fibers form three different manufacturers were tested in a 60Co gamma field at a dose rate of 7.25 x 104 rad/h. The fibers tested were large diameter (1,000 μm), silica core fibers. Two fibers had doped silica cladding; one fiber has a polymer cladding. Of the fiber specimens tested the silica-clad fibers and lower attenuations for a given dose than did the polymer-clad fiber. At 8 x 107 rad total accumulated dose, the fiber with the lowest radiation-induced loss had attenuations of 1.3 dB/m at a wavelength of 405 nm, 1.6 dB/m at 632 nm, and 0.3 dB/m at 905 nm