Pumps On vs. Pumps Off during Recovery
The subject of Reactor Coolant Pump (RCP) operation during a small break loss-of-coolant accident has been the topic of considerable discussion in the nuclear industry. NRC bulletins issued in April, 1979 required at least one Reactor Coolant Pump (RCP) per loop to remain in operation. Subsequent bulletins issued in July, 1979 required immediate tripping of all RCPs upon reactor trip and Safety Injection Actuation Signals (SIAS). The NRC reinforced this tripping criteria by requiring licensees to install equipment that automatically trips the RCPs on SIAS. However, more recently, the NRC has eliminated the automatic trip criteria due to the concerns raised by the nuclear industry and the ACRS. At present, the NRC’s position is that the need for pump trips following a transient or accident should be determined on a case-by-case basis. The ultimate safety of the plant, the staff, and protection of the surrounding environment should be paramount in determining whether RCPs should continue to operate or be shutdown. Yankee Atomic Electric Company (YAEC) is performing plant-specific pump trip studies for the Yankee Plant at Rowe and the Maine Yankee Plant. This paper presents the primary objectives and strategy for these studies and a brief discussion of Yankee Atomic’s overall involvement in the pump trip area.
KeywordsSmall Break Primary System Break Flow Pressurize Water Reactor Reactor Coolant
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