Feasibility of Lead Fast Reactor Heat Exchanger Tube Online Monitoring

Abstract

Online structural health corrosion monitoring in advanced lead fast reactor heat exchangers and molten salt reactor heat exchangers is desirable for detecting tube degradation prior to leaks that may allow mixing of heat exchanger fluids or release of radiological contamination beyond the design containment boundary. This program demonstrates feasibility for a torsional mode sensor to attach to the outside of a long (30-m) heat-exchanger tube in the stagnant flow area where the tube joins the heat-exchanger plenum and where it is possible to protect a sensor and cable from high-force flows. The sensor must be connected by a cable to a monitoring instrument near the heat exchanger. The sensor and cable management approach will be impractical to implement on existing heat exchangers; rather, sensors must be installed in conjunction with heat exchanger fabrication. Previous work has shown the ability of low-temperature lead zirconate titanate (PZT) piezoceramic sensors to detect anomalies of interest in 3-m tubes. These sensors have subsequently been extended to a 30-m tube more representative of commercial power heat exchanger designs. The program will continue to investigate higher-temperature piezoelectric ceramics and long-term performance of high-temperature adhesives and sealants for 350 C lead reactor environments and higher-temperature (700 °C) molten salt environments.