The vibroacoustical environment in two nuclear reactors

Abstract

Laboratory experiments have suggested that thermoacoustic engines can be incorporated within nuclear fuel rods. Such engines would radiate sounds that could be used to measure and acoustically-telemeter information about the operation of the nuclear reactor (e.g., coolant temperature or fluxes of neutrons or other energetic particles) or the physical condition of the nuclear fuel itself (e.g., changes in porosity due to cracking, swelling, evolved gases, and temperature) that are encoded as the frequency and/or amplitude of the radiated sound [IEEE Measurement and Instrumentation 16(3), 18–25 (2013)]. For such acoustic information to be detectable, it is important to characterize the vibroacoustical environments within reactors. We will present measurements of the background noise spectra (with and without coolant pumps) and reverberation times within the 70,000 gallon pool that cools and shields the fuel in the 1 MW research reactor on Penn State’s campus using two hydrophones, a piezoelectric projector, and an accelerometer. Background vibrational measurement taken at the 250 MW Advanced Test Reactor, located at the Idaho National Laboratory, from accelerometers mounted outside the reactor’s pressure vessel and on plumbing, will also be presented to determine optimal thermoacoustic frequencies and predict signal-to-noise ratios under operating conditions. [Work supported by the U.S. Department of Energy.]