Abstract
The paper presents the application of the probabilistic risk assessment (PRA) technique for surveillance test interval (STI) evaluation. Assessment was performed for the reactor protection system (RPS) based upon the living PRA model of the Taipower's Maanshan power plant. Fault tree was developed and analyzed to find the most proper subsystem for test interval relaxation. Event tree analyses were made to calculate core melt down frequencies for test induced transients and anticipated transient without scram events and to evaluate the effect of STI relaxation. Results indicated that an extension of three times of the current RPS test interval has no significant risk impact for the Maanshan plant.