Abstract : A new technique of temperature and strain measurement using fiber Bragg grating (FBG) optical fiber sensor at high temperature in irradiation environment was proposed, in which interrogation of FBGs is carried out based on optical time-domain reflectometry (OTDR). Heating test results showed that stable temperature measurement can be done at 600°C and the reflectance of FBG can be kept constant up to 1000°C. From the strain measurement test on a cantilever, multi-point strain measurement c...
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Development of the FBG sensor for strain and temperature monitoring of high-temperature pipelines of nuclear power reactors

The Sodium Engineering Research Facility was constructed next to the MONJU site to conduct R&Ds such as sodium handling technology, maintenance technology, safety related research and so on. This facility also supports safety and stable operation of the MONJU and is expected to be a foothold of regional and international collaboration between academia and industry. In this paper, overview of this facility and specifications of test equipment will be explained. Also the research program related to main...
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R&D Program of Maintenance Technologies for the Fast Reactors in the Sodium Engineering Research Facility

Abstract: In order to investigate the relationship between the defect size and the corresponding AE parameters, we carried out laboratory tests using a rotating machine and bearing specimens. The rotational speed is 837 rpm and the size of defect diameter of the specimens ranges from 0.25 mm to 1.00 mm, in 0.25 mm steps. AE signals caused from interaction between balls and defects are measured at the rotating shaft using a laser interferometer and also measured on the bearing housing by a piezoelectri...
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Defects measurement of bearings by non-contact acoustic emission method using a laser interferometer

A thermal-resistant fiber Bragg grating (FBG) fabricated by femtosecond laser processing was examined to evaluate the performance as a strain sensor, compared with a conventional FBG se nsor. Each FBG was affixed on a stainless-steel beam along with a strain gauge to measure the Bragg wavelength shift as a function of strain. We used the intensity of the reflection spe ctra from the FBGs as a weighting factor to determine the Bragg wavelengths. Although the strain sensitivity for the thermal-resistant FBG ...
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Development of a health monitoring system using a thermal-resistant fiber Bragg grating for fast reactor power plants: performance evaluation of a thermal-resistant FBG for strain measurement

Fiber Bragg Grating (FBG) is the periodic refractive-index structure in an optical fiber core, where the light of a specific wavelength is reflected. It can be used as te mperature or a distorted sensor by measuring change of the reflective wavelength of FBG. We processed FBG using a Chirped Pulse Amplification titanium sapphire laser. As a result, the peak intensity of reflective spectrum has been successfully improved from -40 dB to -24 dB. Heating test under operational temperature of Fast Breeder React...
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Fabrication and performance assessment of FBG sensor with pulse laser processing