Role of electronic reliability in reactor scram frequency reduction

Over 1200 nuclear plant outages totaling 34 169 lost production hours were associated with instrument, control, and electrical device problems from 1980 through 1982. Internal component failure was the major cause category, representing 45% of the forced outage duration. The major equipment category was electronic module and power supply drift and component failure, representing 15% of this outage time. As a result of these findings, the Electric Power Research Institute initiated a research project to identify and evaluate ways to improve the reliability of power plant instrument and control electronics. Specific practices included: 1) circuit design (e.g., numbers and types of components used); 2) component selection; and 3) module testing. Results show that reliability and drift performance can be improved by a factor of 10 or more. When applied, these improvements can substantially reduce the number of reactor scrams due to electronic equipment failure. The project's methodology and specific findings are described.