Exelon Corporation, the largest operator of nuclear power plants in the U.S., reported on Friday that its earnings declined 12 percent in the second quarter due to a low demand for electricity and more expensive nuclear fuel.

Shares of Exelon dropped 0.96 percent to $53.51 on Friday by 12:21 p.m. on the New York Stock Exchange.

Exelon's net earnings fell to $657 million or 99 cents per share compared to $748 million or $1.13 per share in the same quarter a year ago. The company's 2Q adjusted operating earnings were $683 million or $1.03 per diluted share, higher than the 97 cents per share analysts expected, according to Reuters.

Exelon reaffirmed its guidance range of $4 to $4.30 per share for 2009 adjusted earnings, and forecasts its adjusted earnings for the third quarter of this year to be between 90 cents to $1 per share.

The power company terminated its offer to acquire rival NRG Energy Inc. on Tuesday after nine months waiting for negotiations.