Raj Gopal

Experiences with diagnostic instrumentation in nuclear power plants

Abstract Over the past several years, Westinghouse has developed a coordinated system of on-line diagnostic instrumentation for the acquisition and analysis of data for diagnostics and incipient failure detection of critical plant equipment and systems. Primary motivation for this work is to improve NSSS availability and maintainability through the detection of malfunctions at their inception. These systems encompass the following areas: (1) Vibration Monitoring System for detection of changes in vibrational characteristics of the major components of Nuclear Steam Supply System (NSSS) and Balance of Plant (BOP); (2) Acoustic Monitoring System for detection and location of leaks in the primary system pressure boundary and other piping systems in PWRs; (3) Metal Impact Monitoring for detection of loose debris in the reactor vessel and steam generators; (4) Nuclear Noise Monitoring System for monitoring core barrel vibration; (5) Sensor Response Time Measurement System for detecting any degradation of process sensors; and (6) Transit Time Flow Meter for determining primary coolant flow rate. Summarized in this paper are some of the features of the systems and in-plant experience. These experiences demonstrate that diagnostic systems in combination with analytical and laboratory work for data interpretation do improve plant availability.

Acoustic Monitoring Systems to Assure Integrity of Nuclear Plants

A comprehensive program is underway at the Westinghouse Electric Corporation to develop and evaluate acoustic monitoring systems as a nondestructive testing tool for nuclear power plants that will assure structural integrity with minimum interference to normal power plant activities. A prime requirement for instrumentation for nuclear reactors is that it should function reliably in severe environments for several years. Sensors and instrumentation for source location and display developed for this application are described. Results of tests performed in major test facilities for vessel flaw growth, vessel rupture, and pipe rupture under various operating conditions are summarized. Evaluation performed in nuclear power plants both during hydro tests and operation of plant is presented. Laboratory tests for studying relationships between acoustic emission and fracture mechanics technologies are presented along with a summary of wave propagation results. Measurements, to date, indicate that an acoustic monitoring system has practical applications in nuclear power plants for improving safety and availability of plants.