Radiation hardness of fiber optic sensors for monitoring and remote handling applications in nuclear environments

Abstract

We report on our irradiation experiments on different types of fiber-optic sensors, including three types of commercially available temperature sensors, a multimode extrinsic Fabry-Perot cavity strain sensor and fiber Bragg-gratings. For the temperature sensors, results show that gamma radiation does not interfere with the basic sensing mechanism and that the most critical component turns out to be the optical fiber itself. Semiconductor absorption temperature sensors showed no degradation up to total doses of 250 kGy, whereas the specifications of Fabry-Perot type sensors and fluorescence temperature sensors were already dramatically influenced below the kGy-level. Replacing the optical fiber by a more radiation resistant version allowed to increase the radiation hardness of the fluorescence sensor system by orders of magnitude. The use of fiber-optic sensors in the presence of neutron radiation remains compromised. Similar conclusions are valid for the Fabry-Perot type fiber-optic strain sensors. We finally show that the Bragg-grating resonance wavelength can shift with radiation dose, but that the temperature sensitivity remains unaltered.

Long-Term Temperature Monitoring in CMS Using Fiber Optic Sensors

“…The conventional sensing system with broadband source is limited to 25 km due to Rayleigh scattering [10]. The advantages of small size, light weight, electromagnetic immunity [13], radiation hardness [14], [15], etc, make FBG sensors the ideal devices for a large variety of applications [16] and, in particular, for HEP experiments.…”

One centimeter spatial resolution temperature measurements in a nuclear reactor using Rayleigh scatter in optical fiber

“…In optical fiber sensors, ionizing radiation produces wavelength-dependent radiation-induced attenuation which is exacerbated in measurement techniques whose working principle is based on intensity-related measurements [6,7]. Even in the face of these challenges, however, the Nuclear Regulatory Commission (NRC) concluded in a study conducted in 1998 that fiber optic sensors have unique advantages in nuclear power plant monitoring and control applications, making this technology worthy of further examination.…”

Long-term radiation effects on fibre Bragg grating temperature sensors in a low flux nuclear reactor

“…Commercially available fibre optic sensors may need to be redesigned to withstand substantial radiation doses, in particular when their working principle relies on broad spectrally encoded and intensity-based measurements [8,9]. Fibre optic sensors that spectrally encode the sensing information in a narrow band of wavelengths ( λ < 5 nm) should have a higher radiation acceptance level owing to their insensitivity to broadband radiation-induced losses.…”