Reducing scrams by modifying reactor setpoints for a Westinghouse four-loop plant

The operating statistics of nuclear power plants show that a large number of reactor scrams have occurred and resulted in unscheduled plant outages. The safety and economic significance of unnecessary scrams in nuclear plants warrants concentrated effort. Several approaches are being taken to reduce the scram frequency. They are better operator training, improved equipment reliability, and better operating procedures. The effort on scram reduction at the Nuclear Safety Analysis Center (NSAC) complements these approaches. Specifically, NSAC is performing thermal-hydraulic analyses to relax or eliminate a number of scram setpoints without violating safety limits. It is believed that through this means a significant fraction of the scram occurrences will be eliminated