Long Term Performance & Aging Characteristics of Nuclear Plant Pressure Transmitters

This report provides key results from a 30-month research and development project to study the effects of normal aging on the calibration and response time of nuclear plant pressure, level, and flow transmitters and to develop and validate new methods for testing the performance of the transmitters as installed in nuclear power plants. The project focused on aging tests of complete transmitter assemblies and critical transmitter components; testing the effects of sensing-line length, blockages, and voids on pressure sensor response time; investigating the oil loss phenomenon in Rosemount and other transmitters; validating new methods for on-line testing of pressure transmitter response time; investigating on-line detection of oil loss in Rosemount transmitters; and analyzing Licensee Event Report and Nuclear Plant Reliability Data System databases for pressure sensor failures in nuclear power plants. The authors demonstrated that the practice of response time testing and calibration once every 18 to 24 months is adequate for managing the normal aging of pressure transmitters.