* Power companies warn of potential disruptions
* East Coast nuclear plants take precautions
* Natural gas suppliers warn of pipeline impact
* Gasoline prices rise on potential NY Harbor closure
By Joshua Schneyer and Jeanine Prezioso
NEW YORK, Aug 25 (Reuters) - From nuclear plants to pipelines and refineries, energy companies braced on Thursday for a potentially devastating Hurricane Irene that is barreling toward the most populated part of the United States.
The storm has prompted energy suppliers from North Carolina to Maine to secure equipment, activate emergency plans and warn customers about potential power disruptions.
"We're battening down the hatches," said Alan Griffith of NextEra Energy (NEE.N), which operates the Seabrook nuclear power plant in New Hampshire.
Seabrook was designed to withstand hurricane and tornado-force winds, Griffith said.
Irene was still pummeling the Bahamas late on Thursday afternoon and was expected to make landfall in North Carolina on Saturday.
While the East Coast region has no major offshore oil and gas production like the hurricane-prone Gulf Coast, the stakes are still daunting. The region has around a dozen nuclear plants, a massive oil delivery hub at New York Harbor, and its pipelines and power networks serve more than 100 million Americans.
"Irene appears set to deliver a major blow. Now is the time to prepare for this major hurricane, as impacts appear imminent," MDA EarthSat Weather said.
The agency warned of potentially long power outages, including in New York City, which could have winds more than 75 miles per hour (120 km/hour).
Gloria, the last hurricane to slam the eastern seaboard in 1985, left at least 2.2 million people without power along the East Coast, and caused $1.84 billion in damages in today's dollar terms.
The same broad region is now "well within" the path of Irene, the National Hurricane Center warned on Thursday.
National Grid, which supplies electricity and natural gas to some 3 million customers in the Northeast, enacted a plan that includes racing crews and emergency equipment into place, and warning hospitals to prepare backup power for patients on life support, in case of outages.
"We are very concerned about Irene bringing damaging winds and flooding," said company spokeswoman Amy Zorich.
FACTBOX - East Coast energy infrastructure: [ID:nN1E77O0I1]
Reuters Hurricane Tracker r.reuters.com/san78n
National Hurricane Center www.nhc.noaa.gov
NUCLEAR PLANTS AT THE READY
Progress Energy PGN.N said it was taking safety precautions at its two-unit Brunswick nuclear plant in Southport, North Carolina, where the storm was expected to pass nearby on Saturday. The plant, 22 feet (6.7 meters) above sea level, is built to withstand winds of 128 miles per hour.
National Hurricane Center Director Bill Read warned on Thursday that Irene could blast up the East Coast with Category 2 storm force, packing winds of 96 to 110 mph (154-177 kph).
"Being a large hurricane, tropical storm-force winds will extend far inland," he warned. [ID:nN1E77O0RJ]
Nuclear plant operator Public Service Enterprise Group (PEG.N) said it was securing equipment against storm winds at its Salem and Hope Creek plants, along the Delaware River in Hancocks Bridge, New Jersey.
Checks "are being conducted for objects that could become airborne", said Skip Sindoni, a spokesman for PSEG.
The plants could be taken offline if the storm causes the Delaware River to rise rapidly, he added.
At Indian Point, the large nuclear plant just 38 miles north of New York City, operator Entergy was "securing all material and equipment outside buildings and ensuring that we have a sufficient supply of diesel fuel for backup generators," said spokesman Jim Steets.
Futures prices of gasoline for delivery in the New York Harbor RBU1 rose more than 3 percent on Thursday, as a potential closure of the harbor in coming days threatened to disrupt supplies.
The U.S. Coast Guard has not implemented restrictions on ship traffic in New York Harbor but is monitoring Irene's course.
Tug-boat operator Bouchard Transportation warned that a closure of the harbor could delay loading and unloading of oil cargoes for around a week. [ID:nN1E77O0PY]
The East Coast receives much of its fuel by pipeline from the Gulf Coast or by tanker from Europe.
Six refineries and numerous storage and oil shipping terminals operate on or near the coast.
Jeff Masters of private forecaster Weather Underground warned of potential storm surges that could flood coastal areas of New Jersey and Maryland.
The Colonial Pipeline, a 2.37-million-barrels-per-day refined oil product supply line, stretches 5,500 miles from Texas to the New York Harbor, with "spurs" to other fuel hubs that could be in the storm's path, including in Maryland and Virginia.
Kinder Morgan, another pipeline and terminal operator, was busy fueling vehicles, generators and pumps and securing equipment. It had plans to shut two terminals that handle products including fertilizer and coal in Virginia for 24 hours, starting Saturday.
GDF Suez GSZ.PA, which operates the Everett liquefied natural gas terminal in Massachusetts, said its facility was built to withstand a Category 5 hurricane with winds up to 150 miles per hour.
It has not changed its shipping schedule due to Irene.
(Additional reporting by Janet McGurty, Selam Gebrekidan, Kristen Hays, Bruce Nichols, Robert Gibbons, Jeffrey Kerr, Jeffrey Jones, Eileen Moustakis and David Sheppard; Editing by David Gregorio)