High speed boiling detector based on electrical impedance measurement for advanced in-pile boiling studies

A complete boiling detector measurement system has been designed and built, including sensor, electrical circuit design and configuration, and data acquisition and processing software, with the specific design objective of in-pile application. The measurement system is designed to support experiments at the Transient Reactor Test (TREAT) Facility but is potentially more broadly applicable to other test reactor facilities. An electrically insulating coating with excellent electrically insulative performance has been established for use at PWR water conditions. This coating provides a significant enhancement of the sensor design by increasing the sensitivity of the detector to changes in the effective dielectric by reducing the sensitivity to water conductivity. A complete, packaged in-pile impedance measurement system has been designed, tested, and will be deployed later this year to support TREAT experiments. Sensor performance has been evaluated experimentally over a range of thermal hydraulic conditions and to evaluate sensor sensitivities Detailed performance characterization studies have been performed based on a design of experiments. The transient response of the sensor has been explored using a high speed video recording system. Based on some preliminary assumptions, the results from this test indicate response time of less than the targeted 1 ms.