ECCS room temperature response due to loss of room cooler concurrent with a loss of coolant accident

The Emergency Core Cooling System (ECCS) in a nuclear power plant is designed to maintain adequate core cooling in a loss of coolant accident (LOCA). The system equipment is qualified (EQ) to operate under the thermal environment expected during a LOCA and is located in a compartment cooled by room coolers. Since it is important to maintain the compartment temperature below the EQ temperature in the event of a LOCA, the ECCS is declared inoperable whenever the room coolers are inoperable, such as when they are down for scheduled or unscheduled maintenance. This could lead to forced plant outages. An analysis is performed to determine if the room coolers are needed to maintain the room temperature below the EQ temperature during a LOCA event. The analysis uses a RELAP4 model. It conservatively calculates the temperature response and demonstrates that the EQ temperature is not exceeded during extended ECCS operation without room coolers. This eliminates the need to declare the ECCS system inoperable and contributes to improved plant performance