A verification study on the appropriateness of the diagnostic rules of the emergency operating procedures

A verification study to evaluate the appropriateness of the diagnostic rules of the CE-type EOP for a SLOCA event was performed to address the diagnostic related ambiguities usually existed in behavioral characteristics of the plant systems in response to a specific initiator. A proposed method to verify the appropriateness of the diagnostic rules is to analyze the dynamic behaviors of the diagnostic parameters during the anticipated period of the operator's diagnosis time. The analysis of the dynamic behaviors is conducted by using the thermal-hydraulic (T/H) computer code, MARS, as the break size of the SLOCA event is increased (e.g., 0.76, 1.1, 1.4, 1.6, and 1.9 in.) under a realistic operative status of the related plant systems. According to the analysis results, two of the diagnostic rules revealed a mismatched condition with the simulated physical behaviors for the SLOCA event.