Editorial

5 pages, 199 KiB

Open AccessEditorial

Editorial to the Special Issue Optical Fiber Sensors in Radiation Environments

by Flavio Esposito, Andrei Stancalie, Stefania Campopiano and Agostino Iadicicco

Sensors 2023, 23(22), 9117; https://doi.org/10.3390/s23229117 - 11 Nov 2023

Cited by 1 | Viewed by 722

Optical fibers are well known for their use in high-speed data links and related sensors nowadays find application in different domains, such as structural health monitoring, distributed sensing, but also biological and chemical monitoring [...] Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

Research

Jump to: Editorial, Review, Other

19 pages, 4897 KiB

Open AccessArticle

Cherenkov Radiation in Optical Fibres as a Versatile Machine Protection System in Particle Accelerators

by Joseph Wolfenden, Alexandra S. Alexandrova, Frank Jackson, Storm Mathisen, Geoffrey Morris, Thomas H. Pacey, Narender Kumar, Monika Yadav, Angus Jones and Carsten P. Welsch

Sensors 2023, 23(4), 2248; https://doi.org/10.3390/s23042248 - 16 Feb 2023

Cited by 1 | Viewed by 1777

Abstract

Machine protection systems in high power particle accelerators are crucial. They can detect, prevent, and respond to events which would otherwise cause damage and significant downtime to accelerator infrastructure. Current systems are often resource heavy and operationally expensive, reacting after an event has [...] Read more.

Machine protection systems in high power particle accelerators are crucial. They can detect, prevent, and respond to events which would otherwise cause damage and significant downtime to accelerator infrastructure. Current systems are often resource heavy and operationally expensive, reacting after an event has begun to cause damage; this leads to facilities only covering certain operational modes and setting lower limits on machine performance. Presented here is a new type of machine protection system based upon optical fibres, which would be complementary to existing systems, elevating existing performance. These fibres are laid along an accelerator beam line in lengths of ∼100 m, providing continuous coverage over this distance. When relativistic particles pass through these fibres, they generate Cherenkov radiation in the optical spectrum. This radiation propagates in both directions along the fibre and can be detected at both ends. A calibration based technique allows the location of the Cherenkov radiation source to be pinpointed to within 0.5 m with a resolution of 1 m. This measurement mechanism, from a single device, has multiple applications within an accelerator facility. These include beam loss location monitoring, RF breakdown prediction, and quench prevention. Detailed here are the application processes and results from measurements, which provide proof of concept for this device for both beam loss monitoring and RF breakdown detection. Furthermore, highlighted are the current challenges for future innovation. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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14 pages, 4380 KiB

Open AccessArticle

Design and Characterisation of an Optical Fibre Dosimeter Based on Silica Optical Fibre and Scintillation Crystal

by Michal Jelinek, Ondrej Cip, Josef Lazar and Bretislav Mikel

Sensors 2022, 22(19), 7312; https://doi.org/10.3390/s22197312 - 27 Sep 2022

Cited by 1 | Viewed by 1872

Abstract

In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management of the operation and the environment’s protection. However, in many cases, it is impossible to monitor ionising radiation directly [...] Read more.

In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management of the operation and the environment’s protection. However, in many cases, it is impossible to monitor ionising radiation directly at the required location continuously. This is typically either due to the lack of space to accommodate the entire dosimeter or in environments with high ionising radiation activity, electromagnetic radiation, and temperature, which significantly shorten electronics’ lifetime. To allow for radiation measurement in such scenarios, we designed a fibre optic dosimeter that introduces an optical fibre link to deliver the scintillation radiation between the ionising radiation sensor and the detectors. The sensors can thus be placed in space-constrained and electronically hostile locations. We used silica optical fibres that withstand high radiation doses, high temperatures, and electromagnetic interference. We use a single photon counter and a photomultiplier to detect the transmitted scintillation radiation. We have shown that selected optical fibres, combined with different scintillation materials, are suitable for measuring gamma radiation levels in hundreds of kBq. We present the architecture of the dosimeter and its experimental characterisation with several combinations of optical fibres, detectors, and scintillation crystals. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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8 pages, 2086 KiB

Open AccessArticle

Characterization of the Plastic Scintillator Detector System Exradin W2 in a High Dose Rate Flattening-Filter-Free Photon Beam

by Sara Thrower, Surendra Prajapati, Shannon Holmes, Emil Schüler and Sam Beddar

Sensors 2022, 22(18), 6785; https://doi.org/10.3390/s22186785 - 08 Sep 2022

Cited by 2 | Viewed by 1516

Abstract

(1) Background: The Exradin W2 is a commercially available scintillator detector designed for reference and relative dosimetry in small fields. In this work, we investigated the performance of the W2 scintillator in a 10 MV flattening-filter-free photon beam and compared it to the [...] Read more.

(1) Background: The Exradin W2 is a commercially available scintillator detector designed for reference and relative dosimetry in small fields. In this work, we investigated the performance of the W2 scintillator in a 10 MV flattening-filter-free photon beam and compared it to the performance of ion chambers designed for small field measurements. (2) Methods: We measured beam profiles and percent depth dose curves with each detector and investigated the linearity of each system based on dose per pulse (DPP) and pulse repetition frequency. (3) Results: We found excellent agreement between the W2 scintillator and the ion chambers for beam profiles and percent depth dose curves. Our results also showed that the two-voltage method of calculating the ion recombination correction factor was sufficient to correct for the ion recombination effect of ion chambers, even at the highest DPP. (4) Conclusions: These findings show that the W2 scintillator shows excellent agreement with ion chambers in high DPP conditions. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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14 pages, 3628 KiB

Open AccessArticle

Assessment of a Therapeutic X-ray Radiation Dose Measurement System Based on a Flexible Copper Indium Gallium Selenide Solar Cell

by Dong-Seok Shin, Tae-Ho Kim, Jeong-Eun Rah, Dohyeon Kim, Hye Jeong Yang, Se Byeong Lee, Young Kyung Lim, Jonghwi Jeong, Haksoo Kim, Dongho Shin and Jaeman Son

Sensors 2022, 22(15), 5819; https://doi.org/10.3390/s22155819 - 04 Aug 2022

Cited by 1 | Viewed by 1685

Abstract

Several detectors have been developed to measure radiation doses during radiotherapy. However, most detectors are not flexible. Consequently, the airgaps between the patient surface and detector could reduce the measurement accuracy. Thus, this study proposes a dose measurement system based on a flexible [...] Read more.

Several detectors have been developed to measure radiation doses during radiotherapy. However, most detectors are not flexible. Consequently, the airgaps between the patient surface and detector could reduce the measurement accuracy. Thus, this study proposes a dose measurement system based on a flexible copper indium gallium selenide (CIGS) solar cell. Our system comprises a customized CIGS solar cell (with a size 10 × 10 cm² and thickness 0.33 mm), voltage amplifier, data acquisition module, and laptop with in-house software. In the study, the dosimetric characteristics, such as dose linearity, dose rate independence, energy independence, and field size output, of the dose measurement system in therapeutic X-ray radiation were quantified. For dose linearity, the slope of the linear fitted curve and the R-square value were 1.00 and 0.9999, respectively. The differences in the measured signals according to changes in the dose rates and photon energies were <2% and <3%, respectively. The field size output measured using our system exhibited a substantial increase as the field size increased, contrary to that measured using the ion chamber/film. Our findings demonstrate that our system has good dosimetric characteristics as a flexible in vivo dosimeter. Furthermore, the size and shape of the solar cell can be easily customized, which is an advantage over other flexible dosimeters based on an a-Si solar cell. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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17 pages, 1774 KiB

Open AccessArticle

Characterization of an Innovative Detector Based on Scintillating Fiber for Personalized Computed Tomography Dosimetry

by Clément Devic, Johann Plagnard and Mélodie Munier

Sensors 2022, 22(1), 90; https://doi.org/10.3390/s22010090 - 23 Dec 2021

Cited by 5 | Viewed by 2621

Abstract

For technical and radioprotection reasons, it has become essential to develop new dosimetric tools adapted to the specificities of computed tomography (CT) to ensure precise and efficient dosimetry since the current standards are not suitable for clinical use and for new CT technological [...] Read more.

For technical and radioprotection reasons, it has become essential to develop new dosimetric tools adapted to the specificities of computed tomography (CT) to ensure precise and efficient dosimetry since the current standards are not suitable for clinical use and for new CT technological evolution. Thanks to its many advantages, plastic scintillating fibers (PSF) is a good candidate for more accurate and personalized real-time dosimetry in computed tomography, and the company Fibermetrix has developed a new device named IVISCAN^® based on this technology. In this study, we evaluated performances of IVISCAN^® and associated uncertainties in terms of dose-rate dependence, angular dependence, stability with cumulative dose, repeatability, energy dependence, length dependence, and special uniformity in reference and clinical computed tomography beam qualities. For repeatability, the standard deviation is less than 0.039%, and the absolute uncertainty of repeatability lies between 0.017% and 0.025%. The deviation between IVISCAN^® and the reference regarding energy dependence is less than 1.88% in clinical use. Dose rate dependence results show a maximum deviation under ±2%. Angular dependence standard deviation σ is 0.8%, and the absolute uncertainty was 1.6%. We observed 1% of variation every 50 Gy steps up to a cumulative dose of 500 Gy. Probe response was found to be independent of the PSF length with a maximum deviation

Δ D_{s i z e}

< 2.7% between the IVISCAN^® probe and the 1 cm PSF probe. The presented results demonstrated that IVISCAN^® performances are in accordance with metrology references and the international standard IEC61674 relative to dosemeters used in X-ray diagnostic imaging and then make it an ideal candidate for real-time dosimetry in CT applications. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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13 pages, 5779 KiB

Open AccessArticle

Comparative Study of γ- and e-Radiation-Induced Effects on FBGs Using Different Femtosecond Laser Inscription Methods

by Antreas Theodosiou, Arnaldo Leal-Junior, Carlos Marques, Anselmo Frizera, Antonio J. S. Fernandes, Andrei Stancalie, Andreas Ioannou, Daniel Ighigeanu, Razvan Mihalcea, Constantin Daniel Negut and Kyriacos Kalli

Sensors 2021, 21(24), 8379; https://doi.org/10.3390/s21248379 - 15 Dec 2021

Cited by 7 | Viewed by 2075

Abstract

This work presents an extensive, comparative study of the gamma and electron radiation effects on the behaviour of femtosecond laser-inscribed fibre Bragg gratings (FBGs) using the point-by-point and plane-by-plane inscription methods. The FBGs were inscribed in standard telecommunication single mode silica fibre (SMF28) [...] Read more.

This work presents an extensive, comparative study of the gamma and electron radiation effects on the behaviour of femtosecond laser-inscribed fibre Bragg gratings (FBGs) using the point-by-point and plane-by-plane inscription methods. The FBGs were inscribed in standard telecommunication single mode silica fibre (SMF28) and exposed to a total accumulated radiation dose of 15 kGy for both gamma and electron radiation. The gratings’ spectra were measured and analysed before and after the exposure to radiation, with complementary material characterisation using Fourier transform infrared (FTIR) spectroscopy. Changes in the response of the FBGs’ temperature coefficients were analysed on exposure to the different types of radiation, and we consider which of the two inscription methods result in gratings that are more robust in such harsh environments. Moreover, we used the FTIR spectroscopy to locate which chemical bonds are responsible for the changes on temperature coefficients and which are related with the optical characteristics of the FBGs. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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12 pages, 2903 KiB

Open AccessArticle

Medical Range Radiation Dosimeter Based on Polymer-Embedded Fiber Bragg Gratings

by Marie-Anne Lebel-Cormier, Tommy Boilard, Martin Bernier and Luc Beaulieu

Sensors 2021, 21(23), 8139; https://doi.org/10.3390/s21238139 - 06 Dec 2021

Cited by 4 | Viewed by 2014

Abstract

Fiber Bragg gratings (FBGs) are valuable dosimeters for doses up to 100 kilograys (kGy), but have hardly been used for the low-dose range of a few grays (Gy) required in medical radiation dosimetry. We report that embedding a doped silica fiber FBG in [...] Read more.

Fiber Bragg gratings (FBGs) are valuable dosimeters for doses up to 100 kilograys (kGy), but have hardly been used for the low-dose range of a few grays (Gy) required in medical radiation dosimetry. We report that embedding a doped silica fiber FBG in a polymer material allows a minimum detectable dose of 0.3 Gy for

γ

-radiation. Comparing the detector response for different doped silica fibers with various core doping, we obtain an independent response, in opposition to what is reported for high-dose range. We hypothesized that the sensor detection is based on the radio-induced thermal expansion of the surrounding polymer. Hence, we used a simple physical model based on the thermal and mechanical properties of the surrounding polymer and obtained good accordance between measured and calculated values for different compositions and thicknesses. We report that over the 4 embedding polymers tested, polyether ether ketone and polypropylene have respectively the lowest (0.056 pm/Gy) and largest sensitivity (0.087 pm/Gy). Such FBG-based dosimeters have the potential to be distributed along the fiber to allow multipoint detection while having a sub-millimeter size that could prove very useful for low-dose applications, in particular for radiotherapy dosimetry. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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16 pages, 2654 KiB

Open AccessArticle

Radioluminescence Response of Ce-, Cu-, and Gd-Doped Silica Glasses for Dosimetry of Pulsed Electron Beams

by Daniel Söderström, Heikki Kettunen, Adriana Morana, Arto Javanainen, Youcef Ouerdane, Hicham El Hamzaoui, Bruno Capoen, Géraud Bouwmans, Mohamed Bouazaoui and Sylvain Girard

Sensors 2021, 21(22), 7523; https://doi.org/10.3390/s21227523 - 12 Nov 2021

Cited by 6 | Viewed by 2330

Abstract

Radiation-induced emission of doped sol-gel silica glass samples was investigated under a pulsed 20-MeV electron beam. The studied samples were drawn rods doped with cerium, copper, or gadolinium ions, which were connected to multimode pure-silica core fibers to transport the induced luminescence from [...] Read more.

Radiation-induced emission of doped sol-gel silica glass samples was investigated under a pulsed 20-MeV electron beam. The studied samples were drawn rods doped with cerium, copper, or gadolinium ions, which were connected to multimode pure-silica core fibers to transport the induced luminescence from the irradiation area to a signal readout system. The luminescence pulses in the samples induced by the electron bunches were studied as a function of deposited dose per electron bunch. All the investigated samples were found to have a linear response in terms of luminescence as a function of electron bunch sizes between

10^{- 5}

Gy/bunch and

1.5 \times 10^{- 2}

Gy/bunch. The presented results show that these types of doped silica rods can be used for monitoring a pulsed electron beam, as well as to evaluate the dose deposited by the individual electron bunches. The electron accelerator used in the experiment was a medical type used for radiation therapy treatments, and these silica rod samples show high potential for dosimetry in radiotherapy contexts. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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17 pages, 5362 KiB

Open AccessArticle

Numerical Analysis of Radiation Effects on Fiber Optic Sensors

by Sohel Rana, Harish Subbaraman, Austin Fleming and Nirmala Kandadai

Sensors 2021, 21(12), 4111; https://doi.org/10.3390/s21124111 - 15 Jun 2021

Cited by 3 | Viewed by 2739

Abstract

Optical fiber sensors (OFS) are a potential candidate for monitoring physical parameters in nuclear environments. However, under an irradiation field the optical response of the OFS is modified via three primary mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced emission (RIE), and (iii) radiation-induced [...] Read more.

Optical fiber sensors (OFS) are a potential candidate for monitoring physical parameters in nuclear environments. However, under an irradiation field the optical response of the OFS is modified via three primary mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced emission (RIE), and (iii) radiation-induced compaction (RIC). For resonance-based sensors, RIC plays a significant role in modifying their performance characteristics. In this paper, we numerically investigate independently the effects of RIC and RIA on three types of OFS widely considered for radiation environments: fiber Bragg grating (FBG), long-period grating (LPG), and Fabry-Perot (F-P) sensors. In our RIC modeling, experimentally calculated refractive index (RI) changes due to low-dose radiation are extrapolated using a power law to calculate density changes at high doses. The changes in RI and length are subsequently calculated using the Lorentz–Lorenz relation and an established empirical equation, respectively. The effects of both the change in the RI and length contraction on OFS are modeled for both low and high doses using FIMMWAVE, a commercially available vectorial mode solver. An in-depth understanding of how radiation affects OFS may reveal various potential OFS applications in several types of radiation environments, such as nuclear reactors or in space. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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13 pages, 2141 KiB

Open AccessArticle

Investigation of the Incorporation of Cerium Ions in MCVD-Silica Glass Preforms for Remote Optical Fiber Radiation Dosimetry

by Monika Cieslikiewicz-Bouet, Hicham El Hamzaoui, Youcef Ouerdane, Rachid Mahiou, Geneviève Chadeyron, Laurent Bigot, Karen Delplace-Baudelle, Rémi Habert, Stéphane Plus, Andy Cassez, Géraud Bouwmans, Mohamed Bouazaoui, Adriana Morana, Aziz Boukenter, Sylvain Girard and Bruno Capoen

Sensors 2021, 21(10), 3362; https://doi.org/10.3390/s21103362 - 12 May 2021

Cited by 9 | Viewed by 2355

Abstract

The incorporation of Ce³⁺ ions in silicate glasses is a crucial issue for luminescence-based sensing applications. In this article, we report on silica glass preforms doped with cerium ions fabricated by modified chemical vapor deposition (MCVD) under different atmospheres in order to [...] Read more.

The incorporation of Ce³⁺ ions in silicate glasses is a crucial issue for luminescence-based sensing applications. In this article, we report on silica glass preforms doped with cerium ions fabricated by modified chemical vapor deposition (MCVD) under different atmospheres in order to favor the Ce³⁺ oxidation state. Structural analysis and photophysical investigations are performed on the obtained glass rods. The preform fabricated under reducing atmosphere presents the highest photoluminescence (PL) quantum yield (QY). This preform drawn into a 125 µm-optical fiber, with a Ce-doped core diameter of about 40 µm, is characterized to confirm the presence of Ce³⁺ ions inside this optical fiber core. The fiber is then tested in an all-fibered X-ray dosimeter configuration. We demonstrate that this fiber allows the remote monitoring of the X-ray dose rate (flux) through a radioluminescence (RL) signal generated around 460 nm. The response dependence of RL versus dose rate exhibits a linear behavior over five decades, at least from 330 µGy(SiO₂)/s up to 22.6 Gy(SiO₂)/s. These results attest the potentialities of the MCVD-made Ce-doped material, obtained under reducing atmosphere, for real-time remote ionizing radiation dosimetry. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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15 pages, 4719 KiB

Open AccessArticle

Extreme Radiation Sensitivity of Ultra-Low Loss Pure-Silica-Core Optical Fibers at Low Dose Levels and Infrared Wavelengths

by Adriana Morana, Cosimo Campanella, Jeoffray Vidalot, Vincenzo De Michele, Emmanuel Marin, Imène Reghioua, Aziz Boukenter, Youcef Ouerdane, Philippe Paillet and Sylvain Girard

Sensors 2020, 20(24), 7254; https://doi.org/10.3390/s20247254 - 17 Dec 2020

Cited by 17 | Viewed by 2593

Abstract

We report here the response of a commercial ultra-low loss (ULL) single-mode (SM) pure silica core (PSC) fiber, the Vascade EX1000 fiber from Corning, associated with 0.16 dB/km losses at 1.55 µm to 40 keV X-rays at room temperature. Today, among all fiber [...] Read more.

We report here the response of a commercial ultra-low loss (ULL) single-mode (SM) pure silica core (PSC) fiber, the Vascade EX1000 fiber from Corning, associated with 0.16 dB/km losses at 1.55 µm to 40 keV X-rays at room temperature. Today, among all fiber types, the PSC or F-doped ones have been demonstrated to be the most tolerant to the radiation induced attenuation (RIA) phenomenon and are usually used to design radiation-hardened data links or fiber-based point or distributed sensors. The here investigated ULL-PSC showed, instead, surprisingly high RIA levels of ~3000 dB/km at 1310 nm and ~2000 dB/km at 1550 nm at a limited dose of 2 kGy(SiO₂), exceeding the RIA measured in the P-doped SM fibers used for dosimetry for doses of ~500 Gy. Moreover, its RIA increased as a function of the dose with a saturation tendency at larger doses and quickly recovered after irradiation. Our study on the silica structure suggests that the very specific manufacturing process of the ULL-PSC fibers applied to reduce their intrinsic attenuation makes them highly vulnerable to radiations even at low doses. From the application point of view, this fiber cannot be used for data transfer or sensing in harsh environments, except as a very efficient radiation detector or beam monitor. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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Review

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37 pages, 8014 KiB

Open AccessReview

Fiber Optic Sensors for Harsh and High Radiation Environments in Aerospace Applications

by Alberto Rovera, Alexandru Tancau, Nadia Boetti, Matteo D. L. Dalla Vedova, Paolo Maggiore and Davide Janner

Sensors 2023, 23(5), 2512; https://doi.org/10.3390/s23052512 - 24 Feb 2023

Cited by 9 | Viewed by 3649

Abstract

In the upcoming space revolutions aiming at the implementation of automated, smart, and self-aware crewless vehicles and reusable spacecraft, sensors play a significant role in the control systems. In particular, fiber optic sensors, with their small footprint and electromagnetic immunity, represent a great [...] Read more.

In the upcoming space revolutions aiming at the implementation of automated, smart, and self-aware crewless vehicles and reusable spacecraft, sensors play a significant role in the control systems. In particular, fiber optic sensors, with their small footprint and electromagnetic immunity, represent a great opportunity in aerospace. The radiation environment and the harsh conditions in which these sensors will operate represent a challenge for the potential user in the aerospace vehicle design and the fiber optic sensor specialist. We present a review that aims to be a primer in the field of fiber optic sensors in radiation environments for aerospace. We review the main aerospace requirements and their relationship with fiber optics. We also present a brief overview of fiber optics and sensors based on them. Finally, we present different examples of applications in radiation environments for aerospace applications. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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Other

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10 pages, 2524 KiB

Open AccessLetter

Long-Reach DWDM-Passive Optical Fiber Sensor Network for Water Level Monitoring of Spent Fuel Pool in Nuclear Power Plant

by Hoon-Keun Lee, Jaeyul Choo, Gangsig Shin and Joonyoung Kim

Sensors 2020, 20(15), 4218; https://doi.org/10.3390/s20154218 - 29 Jul 2020

Cited by 7 | Viewed by 3292

Abstract

This paper presents a passive optical fiber sensor network based on the dense wavelength division multiplexing (DWDM) to remotely monitor the water level of the spent fuel pool in nuclear power plants. In states of emergency, such as a tsunami, safety information must [...] Read more.

This paper presents a passive optical fiber sensor network based on the dense wavelength division multiplexing (DWDM) to remotely monitor the water level of the spent fuel pool in nuclear power plants. In states of emergency, such as a tsunami, safety information must be secured for rapid response, in spite of all power losses in the plant. We consider the proposed passive sensor network to be one of the best solutions that is able to provide the remote (more than tens of kilometers) monitoring station with the highly reliable on-site information. The principle of water level measurement is based on the change of Fresnel reflection power coefficient at sensing units, which are installed according to the water levels in a row. The sensing units that play the role of reflector and modulator at the same time are connected to an arrayed waveguide grating (AWG) for DWDM. By measuring the spectrum of the optical signal transferred from the sensing units, the water level can be determined in real-time. However, in the remote sensing, the system performance can be seriously degraded due to the Rayleigh Back-Scattering (RBS) of the seeded amplified spontaneous emission (ASE) light that is induced at the fiber-optic link. As such, we investigate the effect of RBS on the remote (more than tens of kilometers) sensing performance of the proposed network. Following the theoretical analysis, we propose a simple network configuration to overcome the RBS issue by utilizing two different transmission paths: one for downstream of the ASE seed light, and the other for upstream of the optical signals coming from the sensing units. Based on the proposed configuration, the maximum sensing distance can be increased up to 42.5 km without the support of any optical amplifier. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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12 pages, 4645 KiB

Open AccessLetter

A New Setup for Real-Time Investigations of Optical Fiber Sensors Subjected to Gamma-Rays: Case Study on Long Period Gratings

by Andrei Stancalie, Flavio Esposito, Constantin Daniel Neguț, Marian Ghena, Razvan Mihalcea, Anubhav Srivastava, Stefania Campopiano and Agostino Iadicicco

Sensors 2020, 20(15), 4129; https://doi.org/10.3390/s20154129 - 24 Jul 2020

Cited by 4 | Viewed by 3060

Abstract

In this work, we present a new setup for real-time investigations of optical fibers and optical fiber sensors while being subjected to gamma-rays. The investigation of the radiation effects on novel or well-assessed sensing devices has attracted a lot of interest, however, the [...] Read more.

In this work, we present a new setup for real-time investigations of optical fibers and optical fiber sensors while being subjected to gamma-rays. The investigation of the radiation effects on novel or well-assessed sensing devices has attracted a lot of interest, however, the facilities required to do this (when available) are barely accessible to the device to be characterized. In order to reduce the limitations of these types of experiments and ensure a highly controlled environment, we implemented a configuration that permits the on-line testing of optical components inside a Co-60 gamma chamber research irradiator. To show the advantages of this new approach, we present a case study that compares an arc-induced optical fiber long period grating (LPG) irradiated in a gamma chamber with the same type of grating irradiated with gamma-rays from a Co-60 industrial irradiator. In order to better understand the effects of radiation on such components and their behavior in radiation environments, we focus on the homogeneity of the radiation field and parameter customizability as well as the high reproducibility of the experiments. Full article

(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)

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