Safety Analyses Using RETRAN-02 with Relaxed Trip Setpoints on Combustion Engineering Reactors

The reactor protection system (both analog- and digital-based) setpoints of Combustion Engineering nuclear steam supply systems were examined to determine the feasibility of scram reduction by relaxing these setpoints. Representative safety analyses, using RETRAN-02, were performed to demonstrate that acceptable results were obtained with the relaxed setpoints. The steam generator low level, reactor trip on a turbine trip, and thermal margin/low pressure trip setpoints were successfully relaxed.