WASHINGTON — Federal regulators have approved a nuclear reactor designed by Westinghouse Electric. that could power the first nuclear plants built from scratch in a generation.

The Nuclear Regulatory Commission today approved the AP1000 reactor. The certification, effective immediately, will be valid for 15 years.

Westinghouse is headquarted in Cranberry Township.

NRC Chairman Gregory Jaczko said the newly approved design would enhance safety through simplified, passive security functions and other features. He said plants using the design could withstand damage from an airplane crash without significant release of radioactive materials.

The vote is a major step forward for utility companies in Georgia, Florida and the Carolinas that have billions of dollars riding on plans to build AP1000 reactors in the Southeast.

Without NRC approval, the utilities could not get a license to build their plants.