Wireless in-core acoustic telemetry and self-powered sensing

A promising wireless telemetry infrastructure based on acoustic transmission of in-pile measurements (information) is being developed at the Idaho National Laboratory for use in nuclear reactors. A nuclear reactor core used either for research or commercial power production, presents a particularly harsh environment for sensors, while simultaneously imposing challenging constraints on the transmission of their signals outside the reactor. The traditional approach to these problems is to "harden" conventional sensors and their associated signal-conditioning electronics against the degradation introduced by intense fluxes of energetic particles and waves. In this paper, we will demonstrate a completely different approach to telemetry and sensing that exploits a reactor core's energy-rich environment to generate acoustic telemetry signals from self-powered telemeters that produce sounds. These sounds propagate through the reactor's coolant, whether it is gas, water, or liquid metal, through its mechanical structures (e.g., lattice work, pressure vessel, and piping), and can be detected outside the reactor. This novel thermoacoustic (TAC) approach is being developed and tested by Idaho National Laboratory, Pennsylvania State University, and Westinghouse. The objectives for developing a vibroacoustic infrastructure are as follows: • Design infrastructure to transmit data through physical boundaries normally found in nuclear facilities. The sensor data may be gathered simultaneously from multiple sensors and types (e.g., temperature or energetic particle fluxes) by frequency-division multiplexing. • Address the demand for measurement and control technology that can monitor in-core processes and materials through the intrinsic self-powering and acoustically telemetered nature of TAC. • Establish that the acoustic-based infrastructure will operate effectively even under accident scenarios, because the transmitter is self-powered and acoustically telemetered, and because design of TAC telemeters takes advantage of thermal gradients, radiation, cooling fluid, and structures within and surrounding a reactor's core. • Develop a fully-functional telemetry infrastructure to provide reliable and actionable process and material characterization data in research reactors and commercial reactors. The technology required to acoustically telemeter temperature [1] and power information [2] from the core of a nuclear reactor to the exterior, while going through multiple physical boundaries without requiring external electrical power or wiring, is detailed in this paper. In doing so, a new vibro-acoustical paradigm for in-pile telemetry and sensing has been created. This acoustic infrastructure will provide useful information in a reactor accident, such as the one that destroyed the Fukushima complex in March 2011.