On-line monitoring of multiplexed femtosecond Fiber Bragg Gratings exposed to high temperature and high neutron fluence

Nehr, Simon; Cotillard, R.; Laffont, Guillaume; Villard, J-F.; Destouches, C.; Carpenter, David; Daw, Joshua; Calderoni, P.

doi:10.1364/ofs.2018.wf56

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…The radiation sensitivity of type III gratings is also not influenced by thermal treatment, even if performed at very high temperatures, i.e., 750 °C, as shown in Figure 9 d. This agrees with their stability at high temperatures [ 31 ].…”

Section: Radiation Effects On Fbgssupporting

confidence: 71%

“…Concerning the neutrons, whereas several campaigns have been carried out at low flux, up to a fluence of about 10 17 n∙cm −2 [ 19 , 20 , 22 , 31 ], the research targets higher fluences for applications in nuclear reactor cores. The shift induced by a neutron fluence of 10 19 n∙cm −2 (neutron energy of 1 MeV) at a temperature of about 250 °C with an accumulated gamma dose of 0.5 GGy was investigated on different gratings after irradiation [ 23 , 24 ].…”

Section: Radiation Effects On Fbgsmentioning

confidence: 99%

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Radiation Effects on Fiber Bragg Gratings: Vulnerability and Hardening Studies

Morana

Marin

Lablonde

et al. 2022

Sensors

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Fiber Bragg gratings (FBGs) are point optical fiber sensors that allow the monitoring of a diversity of environmental parameters, e.g., temperature or strain. Several research groups have studied radiation effects on the grating response, as they are implemented in harsh environments: high energy physics, space, and nuclear facilities. We report here the advances made to date in studies regarding the vulnerability and hardening of this sensor under radiation. First, we introduce its principle of operation. Second, the different grating inscription techniques are briefly illustrated as well as the differences among the various types. Then, we focus on the radiation effects induced on different FBGs. Radiation induces a shift in their Bragg wavelengths, which is a property serving to measure environmental parameters. This radiation-induced Bragg wavelength shift (RI-BWS) leads to a measurement error, whose amplitude and kinetics depend on many parameters: inscription conditions, fiber type, pre- or post-treatments, and irradiation conditions (nature, dose, dose rate, and temperature). Indeed, the radiation hardness of an FBG is not directly related to that of the fiber where it has been photo-inscribed by a laser. We review the influence of all these parameters and discuss how it is possible to manufacture FBGs with limited RI-BWS, opening the way to their implementation in radiation-rich environments.

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Section: Radiation Effects On Fbgssupporting

confidence: 71%

Section: Radiation Effects On Fbgsmentioning

confidence: 99%

Radiation Effects on Fiber Bragg Gratings: Vulnerability and Hardening Studies

Morana

Marin

Lablonde

et al. 2022

Sensors

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“…HIS work is made in the framework of the instrumentation for nuclear applications (INSNU) project, aiming to develop instrumentation and sensors for experiments in the Jules Horowitz reactor (Cadarache, France). Among other technologies are developed optical sensors: fiber Bragg gratings [1], fiber-optic distributed sensors to measure temperature and strain, pyrometric measurement [2], Fabry-Perot extensometer [3] and confocal chromatic sensor: a displacement sensor which is the object of this article.…”

Section: Introductionmentioning

confidence: 99%

Confocal chromatic sensor for displacement monitoring in research reactor

Agoyan

Fourneau²,

Cheymol³

et al. 2021

EPJ Web Conf.

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Confocal chromatic microscopy is an optical technique allowing measuring displacement, thickness, and roughness with a sub-micrometric precision. Its operation principle is based on a wavelength encoding of the object position. Historically, the company STIL based in the south of France has first developed this class of sensors in the 90’s. Of course, this sensor can only operate in a sufficiently transparent medium in the used spectral domain. It presents the advantage of being contactless, which is a crucial advantage for some applications such as the fuel rod displacement measurement in a nuclear research reactor core and in particular for cladding-swelling measurements. The extreme environmental conditions encountered in such experiments i.e. high temperature, high pressure, high radiations flux, strong vibrations, surrounding turbulent flow can affect the performances of this optical system. We then need to implement mitigation techniques to optimize the sensor performance in this specific environment. Another constraint concerns the small volume available in the irradiation rig next to the rod to monitor, implying the challenge to conceive a miniaturized sensor able to operate under these constraints.

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