Radiation testing of optical fibers for a hot-cell photometer

The potential of in-line photometers for monitoring separation processes in future nuclear fuel reprocessing facilities is considered. Fiber optics will be used to transmit 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 7.25×10⁴ rad/h. The fibers were large-diameter (1000 μm), silica core fibers. Two fibers had a doped silica cladding, one fiber had a polymer cladding. Of the fiber specimens tested the silica-clad fibers had lower attenuations for a given dose than did the polymer-clad fiber. At a 8×10⁷ 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