Three Mile Island Unit 1 Back On-Line after Maintenance

FOR IMMEDIATE RELEASE Ralph DeSantis Three Mile Island Communications 717-948-8930 LONDONDERRY TWP. Pa. (March 5, 2010) – Three Mile Island Unit 1 (TMI-1) began producing carbon-free electricity today at 7:30 p.m ET when operators connected the plant to the regional power grid. TMI-1 generates 852 megawatts of electricity, enough power for more than 800,000 homes. The unit was taken offline on March 4 at 3:02 a.m. ET to perform maintenance on two reactor coolant pumps and on an Isolation Phase Bus Bar in the Turbine Building. The maintenance work involved repairing small oil leaks on both pumps and electrical work on the bus bar. The work has been completed. “We took advantage of being offline to do all the work necessary to ensure the plant is set up for a safe and reliable operating cycle,” said Bill Noll, TMI site vice president. Exelon Corporation is one of the nation’s largest electric utilities with approximately $19 billion in annual revenues. The company has one of the industry’s largest portfolios of electricity generation capacity, with a nationwide reach and strong positions in the Midwest and Mid-Atlantic. Exelon distributes electricity to approximately 5.4 million customers in northern Illinois and southeastern Pennsylvania and natural gas to approximately 485,000 customers in the Philadelphia area. Exelon is headquartered in Chicago and trades on the NYSE under the ticker EXC.