THERMAL HYDRAULIC PARAMETRIC STUDIES OF MULTIPLE SPURIOUS OPERATIONS USING MAAP

摘要

The potential for fire-induced multiple spurious operations (MSOs) of equipment is included as part of the Fire PRA analysis. MSOs could result in a number of adverse conditions including various loss of reactor coolant events, loss of reactor coolant system pressure control, and loss of decay heat sink. Although not all of these scenarios result in a risk significant outcome, it is instructive to determine the bounding limits of the reactor coolant system and associated emergency cooling systems in order to provide guidance for the fire PRA and human reliability analysts. The MAAP code is used to analyze various combinations of MSOs in order to provide bounding information on system capability and operator action timing. The MSOs that are studied that affect the primary system at a pressurized water reactor include the spurious opening of a pressurizer power operated relief valves, letdown valves, and reactor vessel and pressurizer head vents. In combination with these types of MSOs, studies also include the impact of excessive reactor coolant pump seal leakage. Finally, the spurious operation of the primary system pressure control systems is also examined. These studies provide useful information regarding the feasibility of recovering from various MSO combinations, and the related timing to prevent escalation to more challenging transients up to and including core damage. The results demonstrate the degree of importance of potential MSO scenarios to the Fire PRA.