UPDATE 2-Exelon NJ Oyster Creek reactor exits outage

(Updates with NRC comment)

NEW YORK, July 17 (Reuters) - Exelon Corp's (EXC.N) 619-megawatt Oyster Creek nuclear power station in New Jersey exited an outage and ramped up to 72 percent by early Friday, the U.S. Nuclear Regulatory Commission said in a report.

The unit shut on July 12 due to the loss of offsite power caused by a severe electrical storm.

On July 16, the NRC said it initiated a special inspection at the plant in response to the July 12 shutdown. Among other things, the team of four NRC inspectors will review whether any equipment issues, design deficiencies, communication challenges and/or operator performance issues complicated the event.

"While the plant was safely removed from service during the event, several equipment issues arose during the shutdown that we believe bear closer examination," NRC Region I Administrator Samuel Collins said in a release.

At 1:35 a.m. EDT on July 12, with severe weather moving through the area, a lightning strike on an off-site electrical distribution system caused an electrical fault, resulting in a loss of off-site power for Oyster Creek. Nuclear plants send power out onto the grid, but they also take back a certain amount for operational purposes.

As designed, the plant's emergency diesel generators started and began providing power to plant safety systems.

Operators declared an Unusual Event - the NRC's lowest of four levels of emergency classification -- because the loss of off-site power was expected to last for more than 15 minutes. Off-site power was restored at 3:05 a.m. and the Unusual Event was terminated at 4:05 a.m.

The NRC noted several equipment anomalies were observed during the shutdown, including: a switchyard breaker that is used to isolate the off-site electrical distribution system failing to open to clear an electrical fault, which resulted in the loss of off-site power; an emergency diesel generator taking longer than expected to start and load its respective power distribution system; and problems involving level indication equipment for an isolation condenser, a component used to help cool down the reactor during shutdowns.

The NRC is still evaluating whether the event qualified as an unexpected shutdown that could lead to increased NRC oversight, a spokesman at the NRC said.

The NRC increases oversight at reactors that have more than three unplanned shutdowns in 7,000 hours of operation. Since November, Oyster Creek shut about three times due to transformer problems.

Electricity traders guessed an outage related to a storm would likely not qualify for the increased NRC scrutiny.

Oyster Creek, the oldest operating reactor in the nation which entered service in 1969, is located in Forked River in Ocean County about 60 miles east of Philadelphia. The NRC renewed the plant's original 40-year operating license in April 2009 for another 20 years until 2029.

One MW powers about 800 homes in New Jersey.

Exelon, of Chicago, owns and operates more than 38,000 MW of generating capacity, markets energy commodities, and transmits and distributes electricity to 5.4 million and distributes natural gas to 480,000 customers in Illinois and Pennsylvania. (Reporting by Scott DiSavino; Editing by John Picinich)