Self-powered Thermoacoustic Sensor for In-pile Nuclear Reactor Monitoring

Open Access
Author:
Ali, Randall Azhar
Graduate Program:
Acoustics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 15, 2013
Committee Members:
  • Steven Lurie Garrett, Thesis Advisor
  • Matthew Ernest Poese, Thesis Advisor
  • Bernhard R Tittmann, Thesis Advisor
Keywords:
  • acoustics
  • thermoacoustics
  • nuclear
  • temperature
  • sensor
  • in-pile
  • self-powered
  • reactor
  • telemetry
  • wireless
  • sensing
  • fuel-rod
Abstract:
Inspired by the unfortunate events of the Fukushima Daiichi nuclear disaster in Japan, 2011, the Pennsylvania State University began a collaboration with Idaho National Laboratories (INL) to embark upon the development of a self-powered sensor to monitor the temperature inside a nuclear reactor. A resonator manufactured by INL in accordance with dimensions and materials of a nuclear fuel rod was adapted to accommodate a thermoacoustic stack-based (standing wave) engine. This thermoacoustic temperature sensor has resulted in a simple solution that is synergetic with the harsh temperatures of the nuclear reactor. Through electromagnetic radiation, these high temperatures provide the power needed to generate the thermoacoustic oscillations in the device. These acoustic pressure oscillations will propagate throughout a nuclear reactor by sound radiation and its frequency can be measured remotely, which is related to the temperature of the gas in the nuclear fuel rod. This temperature inferred from the frequency of the acoustic oscillation is an effective temperature of the nuclear fuel rod that the acoustic wave spatially averages across the length of the resonator. The interpretation of the thermoacoustic fuel rod resonance frequency as a representation of temperature will be also presented as a T-matrix approximation that properly weights the local sound speed in a resonator with a significant longitudinal temperature gradient. The heat transfer within the device is also discussed, as acoustic streaming which is inherent to the thermoacoustically generated sound wave keeps the device in continuous operation. The streaming results in forced gas convection which removes heat from the ambient end of a stack and passes into the fluid surrounding the fuel rod. In conjunction with the electromagnetic radiation on the hot side of the stack, this eliminates the requirement for any hot or cold heat exchangers. This thermoacoustic sensor also has no physical moving parts and does not require any cables to or from the fuel rod for successful operation.