Vulnerability of OFDR-based distributed sensors to radiations
Résumé
Abstract: Silica-based optical fibers have recently attracted much interest for their use in harsh environments such as the ones encountered in space, military or high energy physics applications. Small size, fast response, light weight and immunity to electromagnetic fields are favorable advantages that often become decisive for fiber sensing to be chosen over other conventional sensing technologies. As an important and representative example, Fukushima’s accident highlighted weaknesses in the safety of nuclear power plants. Since, one of the strategic research axis of the nuclear industry is devoted to the development of novel technologies and sensors to enhance and reinforce the safety in nuclear power plants, especially in the case of accidental conditions associated with a strong increase of the constraints applied to the fiber-based system [1,2]. The objective of this research field is to develop classes of distributed fiber-based sensors using scattering based techniques, powerful solutions for various measurands measurements. Optical fiber properties, indeed, depend on several external parameters such as temperature, strain and
therefore the fiber itself can be used as the sensitive element. Different classes of fiber based sensing techniques have been recently investigated such as Fiber Bragg Gratings (FBGs) for discrete measurements [3,4] and Brillouin [5], Raman [6,7] and Rayleigh [8,9] scattering based techniques for distributed measurements of various environmental parameters. Whereas Brillouin and Raman sensor resolutions remain in the range of one
meter, the advantage of Rayleigh scattering based technique is that it offers very high spatial resolution from 1 cm down to few μm over several hundred meters of fiber length down to few meters respectively. For nuclear industry, integrating fibers-based sensors has to improve the performances (resolution, operating range,…) of security systems in current nuclear power plants (NPPs) and offers new alternative technologies that may overcome the issues identified for next generation of NPPs. Such integration will only be possible if the OFDR based systems are able to resist to the constraints associated with industrial environments, one of the most constraining being the presence of high level of
radiations.
In this work, we carry out a systematic study to highlight the OFDR interest and sensitivity to probe the optical samples at high irradiation dose levels. The responses of five optical fibers types, from radiation hardened to radiation sensitive ones are investigated to explore the influence of both the material compositions and the γ-irradiation on the ODFR sensors. Using these samples, we should highlight the influence of the core dopant concentration on the observed radiation-induced changes as well as the difference observed when the cladding is either radiation resistant or radiation sensitive. Our samples were irradiated using a 60Co source facility reaching total doses varying from 1 MGy up to a maximum of 10 MGy. All the measurements are performed after diverse months from irradiation to study permanents effects induced from these high γ-rays doses.
We’ll present at the conference all the experimental results acquired and use them to estimate the potential of OFDR-based systems for operation in radiation environments.
References
1. S. Girard, J. Kuhnhenn, A. Gusarov, B. Brichard, M. Van Uffelen, Y. Ouerdane, A. Boukenter and C. Marcandella, “Radiation effects on silica-based optical fibers: recent advances and future challenges,” IEEE Trans. Nucl. Sci. 60(13), 2015-2036 (2013).
2. http://www.iaea.org/.
3. Morana, S. Girard, E. Marin, C. Marcandella, P. Paillet, J. Périsse, J.-R. Macé, A. Boukenter, M. Cannas, and Y. Ouerdane , “Radiation tolerant fiber Bragg gratings for high temperature monitoring at MGy dose levels,” Opt. Lett., 39(18), 5313-5316 (2014).
4. A.Faustov, “Advanced fibre optics temperature and radiation sensing in harsh environments,” PhD Thesis (2014).
5. X. Phéron, S. Girard, A. Boukenter, B. Brichard, S. D. Lesoille, J. Bertrand, and Y. Ouerdane, “High γ-ray dose radiation effects on the performances of Brillouin scattering based optical fiber sensors,” Opt. Express, 20(124), 26978-26985 (2012).
6. C. Cangialosi, Y. Ouerdane, S. Girard, A. Boukenter, S. Delepine-Lesoille, J. Bertrand, C. Marcandella, P. Paillet, M. Cannas, “Development of a Temperature Distributed Monitoring System Based on Raman Scattering in Harsh Environment,” NSREC 2014, To be published.
7. C. Cangialosi, S. Girard, A. Boukenter, M. Cannas, S. Delepine-Lesoille, J. Bertrand, P. Paillet, Y. Ouerdane, “Hydrogen and radiation induced effects on performances of Raman fiber-based temperature sensors,” submitted to IEEE J. Lightw. Technol.
8. S. Kreger, D. Gifford, M., Froggatt, A. Sang, R. Duncan, M. Wolfe, B. Soller, “High-Resolution Extended Distance Distributed Fiber-Optic Sensing Using Rayleigh Backscatter,” Proc. SPIE 6530, Sensor Systems and Networks: Phenomena, Technology, and Applications for NDE and Health
Monitoring 2007, 65301R (April 10, 2007)
9. V. Faustov, A. Gusarov, L. B. Liokumovichc, A. A. Fotiadi, M. Wuilpart, P. Mégret, “Comparison of simulated and experimental results for distributed radiation-induced absorption measurement using OFDR reflectometry,” Proc. SPIE, 8794, 87943O (2013).