0000000000023414
AUTHOR
Jocelyn Perisse
Radiation Hardened Optical Frequency Domain Reflectometry Distributed Temperature Fiber-Based Sensors
International audience; We study the performance of Optical Frequency Domain Reflectometry (OFDR) distributed temperature sensors using radiation resistant single-mode optical fibers. In situ experiments under 10 keV X-rays exposure up to 1 MGy( SiO 2 ) were carried out with an original setup that allows to investigate combined temperature and radiation effects on the sensors within a temperature range from 30 ° C to 250 ° C. Obtained results demonstrate that optical fiber sensors based on Rayleigh technique are almost unaffected by radiation up to the explored doses. We show that a pre-thermal treatment stabilize the sensor performance increasing the accuracy on temperature measurement fro…
Coating impact and radiation effects on optical frequency domain Reflectometry fiber-based temperature sensors
International audience; Temperature response of radiation-tolerant OFDR-based sensors is here investigated, with particular attention on the impact of coating on OFS. By performing consecutive thermal treatments we developed a controlled system to evaluate the performances of our distributed temperature sensor and to estimate the radiation impact. We show an important evolution of the temperature coefficient measurements with thermal treatments for non-irradiated fiber and that the amplitude of this change decreases increasing radiation dose. As final results, we demonstrate that sensor performances are improved if we performed a pre-thermal treatment on the fiber-based system permitting to…
Optical frequency domain reflectometer distributed sensing using microstructured pure silica optical fibers under radiations
International audience; We investigated the capability of micro-structured optical fibers to develop multi-functional, remotely-controlled, Optical Frequency Domain Reflectometry (OFDR) distributed fiber based sensors to monitor temperature in nuclear power plants or high energy physics facilities. As pure-silica-core fibers are amongst the most radiation resistant waveguides, we characterized the response of two fibers with the same microstructure, one possessing a core elaborated with F300 Heraeus rod representing the state-of-the art for such fiber technology and one innovative sample based on pure sol-gel silica. Our measurements reveal that the Xray radiations do not affect the capaci…
Vulnerability of OFDR-based distributed sensors to high γ-ray doses
Vulnerability of Optical Frequency Domain Reflectometry (OFDR) based sensors to high γ-ray doses (up to 10 MGy) is evaluated with a specific issue of a radiation-hardened temperature and strain monitoring system for nuclear industry. For this, we characterize the main radiation effects that are expected to degrade the sensor performances in such applicative domain: the radiation-induced attenuation (RIA), the possible evolution with the dose of the Rayleigh scattering phenomenon as well as its dependence on temperature and strain. This preliminary investigation is done after the irradiation and for five different optical fiber types covering the range from radiation-hardened fibers to highl…
Real time monitoring of water level and temperature in storage fuel pools through optical fibre sensors
AbstractWe present an innovative architecture of a Rayleigh-based optical fibre sensor for the monitoring of water level and temperature inside storage nuclear fuel pools. This sensor, able to withstand the harsh constraints encountered under accidental conditions such as those pointed-out during the Fukushima-Daiichi event (temperature up to 100 °C and radiation dose level up to ~20 kGy), exploits the Optical Frequency Domain Reflectometry technique to remotely monitor a radiation resistant silica-based optical fibre i.e. its sensing probe. We validate the efficiency and the robustness of water level measurements, which are extrapolated from the temperature profile along the fibre length, …
Neutron-induced defects in optical fibers
We present a study on 0.8 MeV neutron-induced defects up to fluences of 1017 n/cm2 in fluorine doped optical fibers by using electron paramagnetic resonance, optical absorption and confocal micro-luminescence techniques. Our results allow to address the microscopic mechanisms leading to the generation of Silica-related point-defects such as E', H(I), POR and NBOH Centers.
Influence of neutron and gamma-ray irradiations on rad-hard optical fiber
We investigated point defects induced in rad-hard Fluorine-doped optical fibers using both a mixed source of neutrons (fluences from 1015 to 1017 n/cm2) and γ-rays (doses from 0.02 to 2 MGy) and by a γ-ray source (dose up to 10 MGy). By combining several complementary spectroscopic techniques such as radiation-induced attenuation, confocal micro-luminescence, time-resolved photo-luminescence and electron paramagnetic resonance, we evidenced intrinsic and hydrogen-related defects. The comparison between the two irradiation sources highlights close similarities among the spectroscopic properties of the induced defects and the linear correlation of their concentration up to 1016 n/cm2. These r…
Investigation of Coating Impact on OFDR Optical Remote Fiber-Based Sensors Performances for Their Integration in High Temperature and Radiation Environments
The response of optical frequency-domain reflectometry-based temperature sensors is here investigated in harsh environments (high temperature, high radiation dose) focusing the attention on the impact of the fiber coating on the sensor performances in such conditions. Our results demonstrate that the various coating types evolve differently under thermal treatment and/or radiations, resulting in a small (<5%) change in the temperature coefficient of the sensor. The identified procedure, consisting of a prethermal treatment of the fiber at its maximum coating operating temperature, is here verified up to 150 °C for higherature acrylate and up to 300 °C for polyamide coating. This method allo…
Radiation effects on optical frequency domain reflectometry fiber-based sensor
International audience; We investigate the radiation effects on germanosilicate optical fiber acting as the sensing element of optical frequency domain reflectometry devices. Thanks to a new setup permitting to control temperature during irradiation, we evaluate the changes induced by 10 keV x rays on their Rayleigh response up to 1 MGy in a temperature range from −40°C up to 75°C. Irradiation at fixed temperature points out that its measure is reliable during both irradiation and the recovery process. Mixed temperature and radiation measurements show that changing irradiation temperature leads to an error in distributed measurements that depends on the calibration procedure. These results …
Evaluation of Distributed OFDR-Based Sensing Performance in Mixed Neutron/Gamma Radiation Environments
We report the study of a radiation resistant single mode optical fiber doped with fluorine exposed to mixed neutron and $\gamma $ -radiation up to $10^{17}$ n/cm2 fluence and >2 MGy dose to evaluate its performances when used as the sensing element of a distributed Optical Frequency Domain Reflectometry (OFDR). The use of complementary spectroscopic techniques highlights some differences between the responses of solely $\gamma $ -radiation (10 MGy) or mixed neutron and $\gamma $ ( $10^{17}$ n/cm $^{2}+>2$ MGy) irradiated samples. Those differences are linked to the defect generation rather than to structural changes of the ${a}$ -SiO2 host matrix. We show that a modification of the refracti…
Radiation Vulnerability of Fiber Bragg Gratings in Harsh Environments
International audience; The difficulties encountered in the implementation of a temperature or strain sensor based on fiber Bragg grating (FBG) in a harsh radiative environment are introduced. We present the choices made to select both a radiation-resistant fiber in terms of transmission and also the grating inscription conditions necessary to write radiation tolerant FBGs in such fibers with a femtosecond laser. The radiation response of these gratings was also studied under radiation at dose up to 1 MGy. The comparison between Ge-free and Ge-doped fibers was highlighted.
Radiation Characterization of Optical Frequency Domain Reflectometry Fiber-Based Distributed Sensors
International audience; We studied the responses of fiber-basedtemperature and strain sensors related to Optical FrequencyDomain Reflectometry (OFDR) and exposed to high γ-ray dosesup to 10 MGy. Three different commercial fiber classes areused to investigate the evolution of OFDR parameters withdose, thermal treatment and fiber core/cladding composition.We find that the fiber coating is affected by both thermal andradiation treatments and this modification results in anevolution of the internal stress distribution inside the fiber that influences its temperature and strain Rayleigh coefficients. These two environmental parameters introduce a relative error up to 5% on temperature and strain…