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Abstract The precise and continuous measurement of reactor core temperature is crucial for the safe and efficient operation of light water reactors. Current sensor technologies are limited in their capabilities for continuous monitoring, linearity, and multilocation detection. Magnetostrictive materials, which deform in response to magnetic fields or exhibit magnetization variation when stressed, offer a promising solution through ultrasonic waveguide thermometers. This study prototyped a high-temperature and radiation-tolerant UT consisting of a solenoid and a Galfenol waveguide, and quantified its performance as a thermometer up to 300 °C. The impact of waveguide diameter, ambient temperature, and thermal treatment on UT performance was then thoroughly assessed. Galfenol waveguides with diameters of 0.5 mm, 0.8 mm, and 1.0 mm showed uniform temperature-dependent behavior with minimal hysteresis error when cycled between RT and 300 °C. The acoustic attenuation coefficient decreased with increasing wire diameter, likely due to the combined effects of eddy currents and magneto-mechanical energy conversion. Although thermal annealing at 900 °C for an hour in a nitrogen environment caused significant surface damage to the waveguides, it effectively relieved internal stress, thus minimizing the nonlinearity in the acoustic attenuation coefficient.
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A Methodology for Remote Sensing Inter-Turn Fault Events in Power System Air-Core Reactors, via Simulation of Magneto Quasi-Static Fields in 2D FDTD
We present a numerical methodology to estimate the transient fault currents and to simulate the remote sensing of transient fault information embedded in the magnetic field emissions caused by inter-turn shorts in 60 Hz air-core reactors, thru a magneto quasi-static (MQS) field approximation in the method of Finite-Difference Time-Domain (FDTD) in 2-dimensional (2D) space. The MQS 2D FDTD fields of reactor in normal operation are scaled by correlation against an equivalent circuit model that is derived from application of basic physics principles to parameters of the 3D air-core reactor. The proposed multi-scale quasi-static modeling methodology, based on the reduced c modification, provides fine-feature access down to the single-wire level and can efficiently estimate the transient fault fields and currents due to turn-to-turn short in a reactor with core height in several meters, core diameter in meters, wire diameter in millimeters, and number of turns in the thousands, at 60 Hz; this is accomplished by using computational resources of a typical laptop computer within seconds or minutes, as opposed to days that would be otherwise required without the reduced c modification.
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- Award ID(s):
- 1816542
- PAR ID:
- 10192353
- Date Published:
- Journal Name:
- IEEE Access
- ISSN:
- 2169-3536
- Page Range / eLocation ID:
- 1 to 14
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/ACCESS.2020.3024927
