Aging of nuclear plant instrumentation

Resistance Temperature Detectors (RTDs) and pressure, level and flow transmitters are used to provide a majority of the vital signals required to maintain control and safety in nuclear power plants. Understanding the importance, it is necessary to routinely evaluate the performance of these sensors and determine their limitations with regard to aging during normal operating conditions. This is to insure that sensor performance will not degrade over time, resulting in a compromise in plant safety. To address the concerns over aging and safety, for comprehensive research and development projects were conducted for the U.S. Nuclear Regulatory Commission (NRC) to evaluate the effects of normal aging on calibration stability and response time of RTDs, and pressure level and flow transmitters of the types used for safety-related measurement in nuclear power plants. Each of these projects was performed over a three year period and involved extensive laboratory testing of representative nuclear-grade instrumentation. The overall purpose of each project was to study the aging characteristic of these sensors and insure that adequate test methods and test frequencies are followed by the nuclear industry to insure safety. (Author)