Update:  The U.S. Nuclear Regulatory Commission said an alert at the Oyster Creek plant in Forked River, N.J., ended early Wednesday, October 31.

According to an NRC press release, three reactors (Nine Mile Point 1 in Scriba, N.Y., Indian Point 3 in Buchanan, N.Y.; and Salem Unit 1 in Hancocks Bridge, N.J.) experienced shutdowns as Hurricane Sandy pounded the East Coast.  Another plant, Oyster Creek in New Jersey, remains in an “Alert” due to high water levels in its water intake structure.

NRC says, “Nine Mile Point 1 underwent an automatic shutdown at about 9 p.m. Monday when an electrical fault occurred on power lines used to send power to the grid. It is likely a storm-related event, but the plant’s operators are still evaluating the cause. All plant safety systems responded as designed and the shutdown was safely carried out. Meanwhile, Nine Mile Point 2 experienced a loss of one of two incoming off-site power lines as a result of the fault. One of the plant’s emergency diesel generators started in response to generate power usually provided by the line. Nine Mile Point 2 remained at full power.”

NRC continued, “Indian Point 3 automatically shut down at about 10:40 p.m. Monday in response to electrical grid disturbances caused by the storm. . . the unit was placed in a safe shutdown condition.” And, “Salem Unit 1 was manually shut down by plant operators at about 1:10 a.m. Tuesday as a result of circulating-water pumps being affected by high river level and debris in the waterway.”

Finally, but perhaps of most concern, Oyster Creek had an declared an “Alert” at approximately 8:45 p.m. on October 29th  preceded by an “Unusual Event” at about 7 p.m. when the water level first reached a minimum high water level criteria. The water level rose due to a combination of a rising tide, wind direction and storm surge. While the water level has dropped since peaking earlier today, the Alert remains in place until the level is below the specific criteria for the intake structure, which is where water from an intake canal is pumped into the plant for cooling purposes.

The alert came after water levels at the plant rose more than 6.5 feet above normal, potentially affecting the “water intake structure” that pumps cooling water through the plant.

Those pumps are not essential to keep the reactor cool since the plant has been shut for planned refueling since October 22. Exelon however was concerned that if the water rose over 7 feet it 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.

Exelon also moved a portable pump to the intake structure as a precaution in case it was needed to pump cooling water.  The water levels reached a peak of 7.4 feet — apparently above the threshold — but the pump motors did not flood.  As of 11 a.m. EDT Tuesday the water level was down to 5.8 feet, but they will need the water level to stay below 6 feet for a while before the alert status is taken off.  When the water level falls below 4.5 feet, the plant could then be taken off the unusual event status.

Fortunately for everyone, Oyster Creek, the oldest nuclear plant in the nation, was shut down for a refueling and maintenance outage prior to the storm and the reactor remains out of service.