Units 2 and 3 were both originally licensed by the NRC for 40 years of operation. The NRC limits commercial power reactor licenses to an initial 40 years, but also permits such licenses to be renewed. This original 40-year term for reactor licenses was based on economic and antitrust considerations, not on limitations of nuclear technology. Due to this selected period, however, some structures and components may have been engineered on the basis of an expected 40-year service life. The original federal license for Unit Two expired on September 28, 2013, and the license for Unit Three was due to expire in December 2015. On April 30, 2007, Entergy submitted an application for a 20-year renewal of the licenses for both units. On May 2, 2007, the NRC announced that this application is available for public review. Because the owner submitted license renewal applications at least five years prior to the original expiration date, the units are allowed to continue operation past this date while the NRC considers the renewal application.