Point Beach design flaw gets a red

3 May 2002

The NRC issued a preliminary 'red' finding to Nuclear Management Company (NMC) for a design flaw and operator procedures relating to the auxiliary feedwater (AFW) system at Point Beach.

Red, the highest level in the NRC's four-tier colour-coded system, is of "highest safety significance". If it is confirmed, the red finding would be the second since the introduction of the colour-coding system. The first was for the rupture of steam generator tubes at Indian Point 2.

The Point Beach problem relates to the automatic closing of valves in the AFW system's recirculation line in case of a failure of the pressurised air system. This is possible if there were an earthquake, loss of off-site power, or other disruption. According to the emergency operating procedures, operators would reduce or stop the flow of water to control the steam generator level or mitigate reactor coolant system overcooling. If the operators did not realise that the valves were shut, there could be a lack of recirculating water, resulting in pump damage, and affecting the AFW system's ability to remove heat.

According to the NRC Inspection Report, the significance of the finding "was determined to be high largely due to the relatively high initiating event frequencies that are associated with the involved transients, and the high likelihood of improper actions due to the procedural inadequacies." The report also said that the NRC inspection had found that "inadequate procedural guidance had existed for many years, and that there were several prior opportunities to identify the issue." NRC said that, if it did confirm the red finding in its final analysis, it might not call for all the usual things that are triggered by a finding at that level. For example, the NRC might require only additional oversight and a meeting with the licensee, rather than a broad management review.

The logic behind that position is that the NRC believes that the current management should not be held responsible for a design flaw that predated its arrival, particularly if that management is the one that found the problem and is dealing with it aggressively. The problem had not been found previously because it was not "self-revealing". It required a particular sequence of events: a situation that required the AFW system to be used during shutdown, a failure of the pressurised air system, and operators shutting off the flow to one or more pumps.



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