Structural Health Monitoring of Nuclear Site Facilities Using Optimal Sensor Placement for Damage Detection and Prediction of Failure

Nuclear reactors and associated structural facilities are designed to withstand various types of thermal, vibrational and fatigue loading. Despite careful design considerations, these structures are susceptible to damage due to unforeseen scenarios and can cause imminent danger in retrospect of nuclear radiation leakages, loss of infrastructure and life. To avoid catastrophic outcomes, continuous structural health monitoring (SHM) of such structures ensure safety and efficient maintenance protocols. Finite Element Analysis (FEA) provides a valuable insight into structural performance during operation. Optimal sensor placement (OSP) provides critical and cost-effective structural insight with reduced number of sensors. OSP also allows for utilizing a reduced order FE model for full field estimation of the structural behavior. A D-optimal method is shown to be used in tandem with System Equivalent Reduction Expansion Process (SEREP) for sensor placement and full field estimation of the measurand, respectively. Three test cases using simple structural elements such as beam and plate with various boundary conditions are subjected to single point harmonic and impact load. The strain data collected at the optimal sensor locations has been shown to produce fairly accurate reconstruction of the structural dynamic response when observed at different time instances. The full field strain/displacement fields for the structures enabled to determine load magnitude and location. This concept is proposed to be extended to structures such as reactors, boilers, and piping in nuclear facilities to provide a detailed and comprehensive monitoring of these structures and to avoid damages and failure due to unknown cause(s).