Papers by S. Delepine-Lesoille
Journal of Geophysical Research: Solid Earth, 2013
ABSTRACT
—The integration of Raman-distributed temperature fiber-based sensors (RDTS) into the envisioned ... more —The integration of Raman-distributed temperature fiber-based sensors (RDTS) into the envisioned French deep geological repository for nuclear wastes, called Cigéo requires evaluating how the performances of RDTS evolve in harsh environments, more precisely in presence of H2 or γ-rays. Both H 2 and radiations are shown to affect the temperature measurements made with the single-ended RDTS technology. The amplitudes of the observed effects depend on the different classes of multimode fibers varying in terms of composition and coatings. By selecting the most tolerant fiber structure for the sensing, we could maintain the RDTS performances for such application. A hardening by system studies will be mandatory before integration of single-ended RDTS in Cigéo.
Abstract—We report distributed temperature measurements based on Raman scattering performed durin... more Abstract—We report distributed temperature measurements based on Raman scattering performed during steady state gamma-ray irradiation at a dose rate of 1 kGy(SiO 2)/h and up to a total ionizing dose (TID) of ~ 0.1 MGy. We characterize on-line the evolution of the performances of a single-ended Raman distributed temperature sensor (RDTS) during the -ray exposure of different classes of commercial multimode fibers (MMFs) acting as the sensing element. RDTS is influenced by the radiation-induced attenuation (RIA) phenomena leading to both large errors in the temperature measurements and a diminution of the useful sensing length. The amplitude of the radiation-induced temperature error strongly depends on the fiber choice and on the irradiation conditions. For the single-ended RDTS operation in the targeted Cigéo application the selection of a radiation tolerant sensing fiber will be mandatory, but not sufficient, to overcome the expected severe ambient conditions around radioactive wastes. For efficient temperature sensing up to an accumulated dose of 0.1 MGy, pre-irradiation of the selected radiation resistant (RR) fibers appears also necessary to improve the sensor performances.
Sensors and Actuators A: Physical, 2012
ABSTRACT This paper deals with the study of the capacity of continuously attached long-gage fiber... more ABSTRACT This paper deals with the study of the capacity of continuously attached long-gage fiber optic sensors for a new use: dynamic evaluation of structures.The optical system is first presented, followed by the development of the precise formulation of the measurement data obtained by this sensor when applied to the dynamic analysis of beams, especially under bending oscillations. This sensor allows us to find the curvature mode shapes. Numerical simulations are then performed to estimate the dynamic characteristics of the beam by means of the continuous wavelet transform, using the data obtained with this sensor.Finally, the fiber optic sensors are bonded on a real cantilever beam and experimental data are collected from the optical measurement system, in the case of aftershock free oscillations of the instrumented beam. A similar modal identification procedure as that proposed for numerical simulations is used and the results are compared to those obtained with accelerometers and long strain gauges. This type of sensor, allowing us to find the curvature mode shapes, will be a good candidate for damage detection.
2015 IEEE Sensors Applications Symposium (SAS), 2015
ABSTRACT The use of electromagnetic sensors such as Time Domain Reflectometry (TDR) probes has ga... more ABSTRACT The use of electromagnetic sensors such as Time Domain Reflectometry (TDR) probes has gained increasing importance for long term monitoring of the water content in radioactive waste repositories. TDR probes are sensitive to changes in electromagnetic properties of the surrounding material, a clay rock in our case. Prior to the in situ application, it is mandatory to have an accurate relationship between the electromagnetic properties of the intact host clay rock and the water content. For this purpose, the dielectric properties of intact clay rock samples were systematically studied at frequencies from 1 MHz to 10 GHz with network analyzer technique in combination with coaxial transmission line cells. Samples were conditioned to achieve a water saturation range from 16 % to nearly saturation. The relaxation behavior was quantified based on a generalized fractional relaxation model under consideration of an apparent direct current conductivity assuming three relaxation processes: a high-frequency water process and two interfacial processes which are related to interactions between the aqueous pore solution and mineral particles (adsorbed/hydrated water relaxation, counter ion relaxation and Maxwell-Wagner effects). In a second step, these data are introduced in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rode based TDR-probe embedded in the clay rock. The results are analyzed with classical travel time analysis (onset/inflection) which under/overestimates the value of the permittivity compared to effective permittivity at 1 GHz. Indeed, apparent permittivity contains not only the water-content contribution but also effects due to water-mineral interaction processes. The results demonstrate the capabilities of a combined TD/FD analysis procedure for the monitoring of physical and chemical properties of materials with high frequency electromagnetic sensor techni- ues.
EPJ Web of Conferences, 2011
Structural health monitoring is a key factor in life cycle management of infrastructures. Truly d... more Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on
Structural health monitoring is a key factor in life cycle management of infrastructures. Truly d... more Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument
Journal of Geophysical Research: Solid Earth, 2013
… des Laboratoires des …, 2008
Les capteurs à fibre optique sont des outils exceptionnels pour le contrôle de santé des structur... more Les capteurs à fibre optique sont des outils exceptionnels pour le contrôle de santé des structures. Le présent article vise à dresser l'état de l'art des extensomètres à fibre optique en génie civil, près de 20 ans après leurs premiers développements. Après des ...
Smart Materials and Structures, 2006
We propose a composite-made wave-like sensor body that enables continuous bonding between optical... more We propose a composite-made wave-like sensor body that enables continuous bonding between optical fibre and concrete. Finite element analysis shows that the stiffness of the optical fibre can be adapted to that of the concrete, reducing the strain concentrations and ...
Measurement Science and Technology, 2009
IEEE Sensors Journal, 2000
Sensors and Actuators A: Physical, 2015
ABSTRACT We evaluated comparatively the radiation sensitivity of two long period gratings (LPGs) ... more ABSTRACT We evaluated comparatively the radiation sensitivity of two long period gratings (LPGs) manufactured in a SMF28TM optical fiber through the melting-drawing method based on CO2 laser assisted by a micro-flame, of a commercial fiber Bragg grating (FBG), and of a commercially available Draw Tower Grating (DTG), all exposed to gamma radiation. The tests were run on-line using the optical frequency domain reflectometry (OFDR) technique, in order to provide unequal sensitivity, the gratings being wavelength multiplexed. The dose rate dependence of the LPGs response was evaluated for dose rates of 0.37 kGy/h and 0.24 kGy/h, up to the total dose of (33.9 +/− 0.8) kGy and (21.5 +/− 0.5) kGy. The FBG and DTG proved to be radiation hardened having a radiation sensitivity of 12 pm/kGy, while the LPGs radiation sensitivity was as high as 1.2 nm/kGy under the same irradiation conditions. A recovery of the radiation induced wavelength shift for LPGs was noticed at room temperature, at a rate of 2.2 pm/h, over a 211 h period. The effect of LPG wavelength change after exposure to gamma-ray can be exploited in the development of radiation dosimeters, up to the dose of 10 kGy, when saturation appears. The temperature sensitivity of the LPG2 changed from 48 pm/°C before the irradiation, to 50 pm/ °C after the irradiation for a total dose of 21 kGy
IEEE Photonics Journal, 2014
ABSTRACT The paper reports the outcomes of the tests we conducted as on-line measurements for the... more ABSTRACT The paper reports the outcomes of the tests we conducted as on-line measurements for the evaluation of one optical fiber long period grating produced by fusion technique in a single mode radiation hardened optical fiber, and subjected to gamma irradiation. During the irradiation the grating temperature was monitored. Before the irradiation the temperature sensitivity of the grating was 27.7 pm/OC, while the value of this parameter post irradiation was found to be 29.3 pm/OC. The spectral characteristics of the grating were measured (i) in the laboratory with an ANDO AQ6317C optical spectrum analyzer and (ii) on-line, for the first time, with a LUNA OBR 4600 backscatter reflectometer. operating in the frequency acquisition mode. Such on-line measurement enables the study of recovery effects during the irradiation. The wavelength dip of the grating shifted under gamma irradiation, with 16 pm/kGy for the maximum total dose of 45 kGy. At room temperature the recovery of the irradiation induced shift of the wavelength dip was almost complete in about 120 h, at a rate of 6.7 pm/h. Post irradiation heating of the sensor produced the reversing of the recovery effect. The investigation indicated that up to 45 kGy the grating is more sensitive to radiation than other optical fiber sensors.
2014 Third Mediterranean Photonics Conference, 2014
ABSTRACT The paper reports the outcomes of the tests we conducted as on-line measurements for the... more ABSTRACT The paper reports the outcomes of the tests we conducted as on-line measurements for the evaluation of one optical fiber long period grating produced by fusion technique in a single mode radiation hardened optical fiber, and subjected to gamma irradiation. During the irradiation the grating temperature was monitored. Before the irradiation the temperature sensitivity of the grating was 27.7 pm/OC, while the value of this parameter post irradiation was found to be 29.3 pm/OC. The spectral characteristics of the grating were measured (i) in the laboratory with an ANDO AQ6317C optical spectrum analyzer and (ii) on-line, for the first time, with a LUNA OBR 4600 backscatter reflectometer. operating in the frequency acquisition mode. Such on-line measurement enables the study of recovery effects during the irradiation. The wavelength dip of the grating shifted under gamma irradiation, with 16 pm/kGy for the maximum total dose of 45 kGy. At room temperature the recovery of the irradiation induced shift of the wavelength dip was almost complete in about 120 h, at a rate of 6.7 pm/h. Post irradiation heating of the sensor produced the reversing of the recovery effect. The investigation indicated that up to 45 kGy the grating is more sensitive to radiation than other optical fiber sensors.
(35 words) The radiation tolerance of different distributed Raman based sensor classes and/or the... more (35 words) The radiation tolerance of different distributed Raman based sensor classes and/or their responses evolution during gamma-ray exposure at 1 kGy/h dose rate (to reach ~0.1 MGy) was investigated to monitor radioactive waste deep geological repository. Abstract—We report distributed fiber optic temperature measurements based on Raman scattering performed during -radiation with a dose rate of 1 kGy/h to reach accumulated dose up to ~ 0.1 MGy. We assess the performances evolution of Raman distributed temperature sensor (RDTS) comparing different classes of standard multimode fibers (MMFs) irradiated in view of their integration into the French deep geological repository for radioactive waste, called Cigeo (in project). Under -rays the sensor response is affected by the radiation induced attenuation phenomena leading to errors in the RDTS temperature measurements. The amplitude of this error strongly depends on the fiber type and the irradiation conditions. For the single-ended RDTS operation in the Cigeo application, a selection of the most online-radiation tolerant sensing fiber will be mandatory.
Conference Presentations by S. Delepine-Lesoille
Brillouin optical time-domain analysis (BOTDA) sensors offer remarkable advantages for the survei... more Brillouin optical time-domain analysis (BOTDA) sensors offer remarkable advantages for the surveillance of the planned French deep geological radioactive wastes repository, called Cigéo 1,2. In this work we study the performances of Brillouin distributed sensors in harsh environment. We evaluate the radiation tolerance of different sensor classes and their responses evolution during -ray exposition with 1kGy/h dose rate (to reach ~0.2MGy) and after 1, 3, 6 and 10 MGy accumulated doses. Measurements on strained Ge-doped SMF are reported to highlight the variation on Brillouin scattering proprieties, both intrinsic frequency position of Brillouin shift and its dependence on temperature and strain.
Uploads
Papers by S. Delepine-Lesoille
Conference Presentations by S. Delepine-Lesoille