Zion Startup and Operating Experience

This paper describes several significant events related to the startup and initial operation of Zion Generating Station. Among the events described are a diode installation that resulted in failure of one redundant Engineered Safeguard logic and a wiring reversal that negated one safeguards function. A series of electrolytic capacitor failures are presented and the NSSS vendor´s proposed corrective action is supplied. Three major electrical failures are described; these include a reactor coolant pump motor and both main generators.