Nine Mile Point (Unit 1), Indian Point (Unit 3) in the State of New York were automatic shutdowns because of electrical grid problems. Salem (Unit 1) in New Jersey was manually shut down because of high river water levels and debris in the water.
Oyster Creek (NJ)'s alert due to the high water levels at the water intake remains.
From NRC press release (10/30/2012, 10AM; emphasis is mine):
NRC MAINTAINS HEIGHTENED WATCH OVER NUCLEAR PLANTS IMPACTED BY SANDY; THREE REACTORS EXPERIENCED SHUTDOWNS DURING STORM; OYSTER CREEK PLANT REMAINS IN ALERT
The U.S. Nuclear Regulatory Commission continues to maintain its heightened watch over nuclear power plants in the Northeastern U.S. impacted by Sandy. Three reactors experienced shutdowns during the storm while another plant, Oyster Creek in New Jersey, remains in an “Alert” due to high water levels in its water intake structure.
The three reactors to experience trips, or shutdowns, during the storm are Nine Mile Point 1 in Scriba, N.Y., Indian Point 3 in Buchanan, N.Y.; and Salem Unit 1 in Hancocks Bridge, N.J.
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.
Indian Point 3 automatically shut down at about 10:40 p.m. Monday in response to electrical grid disturbances caused by the storm. All safety systems responded as designed and the unit was placed in a safe shutdown condition.
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. The circulating-water system is used to cool down steam generated by the reactor; it is a closed system that does not come into contact with any radioactivity.
At Oyster Creek, the Alert was declared at approximately 8:45 p.m. An alert is the second-lowest level of emergency classification used by the NRC. The Alert was 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 will not be exited 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. Oyster Creek was shut down for a refueling and maintenance outage prior to the storm and the reactor remains out of service.