Which LOCA scenario is used as an example of a DBA-BWR?

• A. LOCA - double ended rupture of reactor coolant piping with simultaneous loss of off-site power
• B. Steam turbine failure
• C. LOCA - instantaneous shear of recirc pump suction line with simultaneous loss of normal aux power and feedwater flow
• D. Loss of off-site power without LOCA

Answer: (C)

This question tests recognizing which LOCA scenario is used to illustrate a DBA-BWR condition. The best scenario is a LOCA caused by an instantaneous shear of the recirculation pump suction line, occurring together with a loss of normal auxiliary power and loss of feedwater flow. This combination removes the usual water makeup path and the normal power supply, so the plant cannot rely on feedwater or on normal power to keep the core cooled. It forces the safety systems—like the emergency core cooling systems and pressure/level control actions—to operate under stressed conditions, which is the purpose of a DBA-BWR example. The other options don’t represent a LOCA scenario with the same BWR-specific cooling paths and concurrent loss of power/feedwater, or describe conditions outside the typical DBA-BWR LOCA testing scope.