Acoustic Emission Monitoring of Piping System for Advanced Nuclear Reactors

High-temperature operation of vessels and piping systems in advanced nuclear reactors makes them susceptible to creep damage. To address this issue, the acoustic emission (AE) method was investigated as a structural health monitoring solution for detecting the initiation and evolution of creep damage. Stainless steel coupons were tested at 650 degrees C to induce different creep mechanisms. Two AE sensors functional at room temperatures with a frequency bandwidth of 100-300 kHz were attached with waveguides, which were welded to the coupons to transmit and minimize the signal loss between the coupon and the waveguide. Once the AE characteristics of creep damage were identified, they were compared with the attenuation curve of an actual piping network at Argonne National Laboratory, Mechanisms Engineering Test Loop (METL) facility. The liquid sodium piping system at the METL facility was instrumented with twelve piezoelectric sensors strategically placed using waveguides to accommodate the high operational temperature. The AE simulations using pencil lead break (PLB) testing showed that the piping system operates as an excellent waveguide. The AE waveforms obtained from the laboratory setup and the attenuation curve of the actual piping system were analyzed to translate the laboratory-dependent AE data for creep damage to a realistic condition.