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Université Jean Monnet – Saint-Etienne |  |
Journal articles
Study of Fiber Bragg Grating Samples Exposed to High Fast Neutron Fluences
Abstract : Fiber Bragg grating (FBG) sensors are expected to provide valuable data in extreme radiation environments associated with nuclear research reactors. However, when the fast neutron fluence reaches 10^18 -10^19 n/cm 2 , the radiation-induced changes in the material density and refractive index may drastically bias the measurements. This paper evaluates the radiation effect on the FBG performances by comparing their properties before and after their exposure to fast neutron fluences exceeding 10^19 n/cm2 (E 1 MeV).
We studied the responses of FBGs manufactured by three different laboratories in the same singlemode optical fiber but using different inscription conditions. The Bragg wavelength and the reflectivity were measured before and after irradiation thanks to a dedicated mounting. For nearly all FBGs, the Bragg peak remains visible after the irradiation while the radiation-induced Bragg wavelength shifts (RI-BWSs) vary from a few picometers (equivalent temperature error <;1 °C) to nearly 1 nm (~100 °C error) depending of the FBG inscription conditions. Such high RI-BWSs can be explained by the huge refractive-index variation and compaction observed for bare fiber samples through other experimental techniques. Our results show that by using specific hardening techniques, the FBG-based temperature measurements in a nuclear research reactor experiment may become feasible.
Keywords :
radiation-induced Bragg wavelength shifts
single-mode optical fiber
material density
radiation-induced changes
fast neutron fluence
nuclear research reactors
high fast neutron fluences
extreme radiation environments
optical fiber sensors (OFSs)
neutron
fiber Bragg grating (FBG)
gamma
Temperature measurement
neutron flux
optical fibre testing
optical variables measurement
reflectivity
refractive index
fiber Bragg grating sensors
inscription conditions
high radiation-induced Bragg wavelength shifts
FBG based temperature measurements
nuclear research reactor experiment
compaction
huge refractive-index variation
FBG inscription conditions
radiation effect
optical fibers
https://hal-ujm.archives-ouvertes.fr/ujm-01926002
Contributor : Sylvain Girard <>
Submitted on : Sunday, November 18, 2018 - 8:15:23 PM
Last modification on : Tuesday, April 28, 2020 - 11:28:11 AM
Contributor : Sylvain Girard <>
Submitted on : Sunday, November 18, 2018 - 8:15:23 PM
Last modification on : Tuesday, April 28, 2020 - 11:28:11 AM
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