UPDATE 1-NRC renews Exelon Pa. Three Mile Isl reactor license

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NEW YORK, Oct 22 (Reuters) - The U.S. Nuclear Regulatory Commission on Thursday renewed the operating license for Exelon Corp’s 786-megawatt Unit 1 at the Three Mile Island nuclear plant in Pennsylvania for an additional 20 years until 2034.

The current license for Three Mile Island 1 expires April 19, 2014.

The sister unit at the plant near the Pennsylvania state capital of Harrisburg created worldwide headlines in 1979 when it partially melted down in the worst U.S. nuclear power accident.

The accident made Three Mile Island synonymous with the dangers of nuclear power and helped stop expansion of the U.S. nuclear industry until the recent slow-moving “nuclear renaissance.”

Exelon, the biggest nuclear power operator in the United States, did not own Three Mile Island at the time of the accident.

Since 2000, when the NRC approved its first 20-year license renewal, the Commission has granted new licenses for 55 reactors, including Three Mile Island. The agency is now evaluating 13 applications for 20 units.

There are 104 reactors operating in the United States.

Exelon filed for the renewal in January 2008. It usually takes the NRC about 22 months (November 2009) to make a decision without a hearing and about 30 months (July 2010) with a hearing. There were no hearings requested and none granted on the Three Mile Island application.

The NRC uses the renewal process to determine how an operator will manage the aging of a reactor. It is a two-step process, including a safety and environmental review.

The Three Mile Island 1 reactor, which entered service in 1974, is located in Middletown in Dauphin County about 10 miles southeast of Harrisburg.

One megawatt powers about 800 to 1,000 homes in Pennsylvania.

Exelon, of Chicago, owns and operates more than 38,000 MW of generating capacity, markets energy commodities, and transmits and distributes electricity to about 5.4 million customers in northern Illinois and southeast Pennsylvania and natural gas in the Philadelphia area. (Reporting by Scott DiSavino; Editing by Christian Wiessner)