The design of a fiber-optic dosimeter, which determines the radiation dose from the difference of radiation-induced attenuation (RIA) Δα measured in a P-doped silica fiber at λ = 413 and 470 nm, is presented along with its first test results under gamma-radiation (dose rates 0.00064 and 0.0066 Gy/s, maximal dose ~2Gy). The dose-dependence of Δα as well as of RIA at individual wavelengths is found to be well described by a power law, the exponent lying in the range 0.90-0.94. In contrast to RIA at individual wavelengths, Δα is found not to depend on dose rate and to decay only slightly on termination of irradiation. Therefore, using Δα for dosimetry is argued to be more promising.

Radiation-induced attenuation (RIA) at wavelength λ=1.55 μm as well as the RIA spectra were investigated in optical fibers during and after irradiation at the IVG.1M nuclear reactor (Republic of Kazakhstan). The fibers studied were single-mode at λ=1.55 μm, had an undoped-silica-core and an-F-doped-silica cladding (”pure-silica fibers, PSFs”), and were provided by different manufacturers. In addition to five PSFs, a single-mode revolver hollow-core fiber was also studied. The PSFs had different coating materials: polyimide, copper, or aluminum. All fibers were exposed to three runs of reactor irradiation at enhanced temperature (155-355 °C) so that by the end of the 3rd run, the fast-neutron fluence amounted to Φ=4.46∙1017n/cm2 and γ-dose to D=2.91∙107 Gy. The total induced loss at λ=1.55 μm was found to be composed of 1) RIA, 2) bending loss (BL), caused by thermal expansion of the copper cylinder the PSFs were wound on, and 3) thermo-induced microbending loss (ML) in Cu-coated PSFs. At the end of the irradiation campaign, the net RIA in PSFs proved to lie in the interval of 0.12-0.16 dB/m, which appears to be admissible to intrareactor transport fibers. It was confirmed that long-wavelength RIA tail is the only RIA origin at λ=1.55 μm in PSFs in such strong radiation fields. The hollow-core fiber was found to feature zeroth RIA throughout the campaign.

Radiation-induced absorption (RIA) of light in five isotropic optic fibers (OFs) with a core of undoped silica glass (SiO2) and a fluorosilicate cladding and one birefringent OF of the...

Nuclear industry may benefit from the implementation of Optical Fiber Sensor (OFS) technology. This is obvious if the OFS integrates features that meet specific nuclear sensing needs, such as distributed dose monitoring in underground radioactive waste disposals. The use of radiation sensitive fibers for dosimetry has already been proposed in literature. In this paper, we report on our gamma irradiation of such dedicated Ge-P co-doped and pure P-doped optical fiber, fabricated by the Fiber Optic Research Center in Moscow. We show that after a careful selection of the wavelength at which the radiation-induced attenuation is measured, it is possible to reconstruct the dose within 20% accuracy by means of a linear model or a second order polynomial, depending on the temperature.