The plant's operator, Exelon, says there is no threat to public safety, or the structural integrity of the plant.
Those pumps are not essential since the reactor has been shut for planned refuelling since Oct. 22. However, a further rise to 7 feet could submerge the service water pump motor that is used to cool the water in the spent fuel pool, potentially forcing it to use emergency water supplies from the in-house fire suppression system to keep the rods from overheating.
On Tuesday, an NRC spokesman said the levels reached a peak of 7.4 feet -- apparently above the threshold. As of 6:10 a.m. EDT waters were at 6.5 feet, with the next high tide at 11:45 a.m. He said the company had moved a portable pump to the water intake structure as a precaution, but has not needed to use it.