Among the various immobile pieces of infrastructure in the path of the East Coast hurricane are around 20 nuclear reactors, from Calvert Cliffs in southern Maryland to Pilgrim in Plymouth, Mass., and Vermont Yankee, just north of the Massachusetts line in Vernon, Vt. But the industry and regulatory officials say that this is an anticipated challenge.

At the Nuclear Regulatory Commission’s mid-Atlantic office in King of Prussia, Pa., Diane Screnci, a spokeswoman, said that reactors in the region have undertaken routine preparations. “They all have severe weather procedures,’’ she said. “They’ve gone through their procedures, making sure they have appropriate staff able to be on site, and that anything that’s outside is fastened down.’’



“They’re all designed to withstand the natural phenomena, including hurricanes and what comes with hurricanes — high winds, high water, that kind of thing,’’ she said.

Reactors operate under licenses that require them to shut down if conditions are too severe, and some reactor operators could shut down even before they are required to do so if they choose to, she said. But none had done so by Sunday afternoon. The conditions that would require a shutdown differ from plant to plant and involve factors like wind speed and flooding potential.

The most severe weather to afflict nuclear reactors may have been Hurricane Andrew, in August 1992, which was a Category 5 storm when it hit the Turkey Point reactors 25 miles south of Miami. The plant lost telephone communications with the outside world, and the access road was blocked by fallen trees, but there was no significant damage to safety systems, the regulatory commission found later.

There was significant damage to two adjacent generators that run on fossil fuels, though. In that storm, there were gusts up to 175 miles per hour, stronger than what Sandy is expected to produce.

The Waterford 3 reactor, 20 miles west of New Orleans, weathered Katrina in August 2005. The management kept two teams of operators on site, and used satellite phones for communications after landlines were knocked out.

Hurricane Irene in August 2011 led to the shutdown of the Oyster Creek reactor in Toms River, N.J., 60 miles east of Philadelphia, and one of the two Calvert Cliffs reactors in Maryland around 50 miles south of Washington. And the two Salem reactors in New Jersey just south of the Delaware Memorial Bridge cut their power output to reduce their need for cooling water because debris was entering the cooling water channels.

In normal operation, reactors rely on power from the grid to drive some critical equipment. If the high-voltage grid is disrupted, the reactors will automatically shut down, and diesel generators will start up.

That’s what happened at the Tennessee Valley Authority’s Browns Ferry reactors, 30 miles west of Huntsville, Ala., in April, 2011 when tornadoes tore down power lines.

A previous version of this post misstated the number of Calvert Cliffs reactors that were shut down during Hurricane Irene. it was one reactor, not two.