Loss-of-feedwater transients for the Zion 1 Pressurized-Water Reactor.

The response of the Westinghouse Zion-1 pressurized water reactor to transients initiated by loss of main feedwater with auxiliary feedwater unavailable was simulated using the Transient Reactor Analysis Code (TRAC). The normal response mode in which emergency systems perform as designed was first studied to identify critical equipment performance and operator actions necessary for normal recovery. Subsequent analyses were performed to determine the effects of additional equipment failures, such as valves sticking open, and delayed or degraded operation of emergency systems. Strategies were developed for operator actions not covered in existing emergency procedures and were tested using TRAC simulations to evaluate their effectiveness in preventing core uncovery.