Feb. 17 (Bloomberg) -- New nuclear power plants must be built to ensure that a strike by a commercial airplane won’t result in a radioactive release, the U.S. Nuclear Regulatory Commission said.

“This is a common-sense approach to address an issue raised by the tragic events of Sept. 11, 2001,” Dale Klein, chairman of the commission, said in an e-mail statement today after the final rule was passed.

Companies including Dominion Resources Inc., Exelon Corp. and Entergy Corp. have already filed applications seeking to build reactors and would be subject to the new standards. The commission began changing its security requirements after the Sept. 11 attacks, in which hijacked airliners slammed into the World Trade Center in New York and the Pentagon near Washington.

The commission has said it’s expecting applications by the end of 2010 to build as many as 33 reactors. There are 104 operating reactors in the U.S., which generated 19 percent of the nation’s power last year, according to the Energy Information Administration. The new rule doesn’t affect existing facilities.

“The NRC continues to be confident that existing reactors will continue to protect public health and safety even in the case of a large commercial aircraft impact,” Scott Burnell, a spokesman for the commission, said in an interview.

“This decision will go a long way toward protecting Americans from the horrific possibility that terrorists could target our nuclear plants with large aircraft,” Representative Edward Markey, a Massachusetts Democrat, said in an e-mailed statement.

To contact the reporter on this story: Tina Seeley in Washington at tseeley@bloomberg.net.

Last Updated: February 17, 2009 17:17 EST