Opening the door to a new generation of nuclear reactors, federal regulators on Thursday approved a design that a nuclear watchdog group acknowledged is an improvement but still not ideal. The AP1000 reactor, designed by Westinghouse Electric Co., is safer than the current generation of U.S. reactors, which date back 30 years or more, members of the Nuclear Regulatory Commission said in voting for approval. \"The design provides enhanced safety margins through use of simplified, inherent, passive, or other innovative safety and security functions, and also has been assessed to ensure it could withstand damage from an aircraft impact without significant release of radioactive materials,\" NRC Chairman Gregory Jaczko said in a statement. Fears of an aircraft impact were heightened after the Sept. 11, 2001, attacks. The Nuclear Energy Institute praised the approval. NEI\'s chief nuclear officer, Tony Pietrangelo, called it \"an important step closer to the construction and operation of advanced-design reactors that can strengthen America’s energy security while producing large amounts of affordable electricity to help drive economic growth.\" Key features of the AP1000 are its fewer moving parts than in traditional reactors, especially in an emergency where radioactive fuel needs to be cooled. Current systems rely on pumps to supply water, but the AP1000 uses a massive water tank atop its structure that uses gravity to release the coolant. Utilities in Georgia and South Carolina are seeking approval to build four AP1000 reactors, which Westinghouse touts with a trademarked campaign: \"The Nuclear Renaissance Starts Here.\" China is among its earliest buyers, with four AP1000s being built there now. No nuclear reactors have been built in the U.S. since the 1979 Three Mile Island accident and talk in recent years of a renaissance was dealt a setback with Japan\'s Fukushima disaster last March. The Obama administration, which has offered the project in Georgia $8.3 billion in loan guarantees, is \"committed to restarting America’s nuclear industry -- creating thousands of  jobs in the years ahead and powering our nation’s homes and businesses with domestic, low-carbon energy,\" Energy Secretary Steven Chu said Thursday in praising the approval. He said it \"marks an important milestone towards constructing the first U.S. nuclear reactors in three decades.\" Nuclear energy does have an advantage over fossil fuels in that it does not emit the greenhouse gas carbon, but it faces stiff price competition from natural gas, which is much cleaner than oil and has dropped dramatically in price. Moreover, building a nuclear reactor is much more expensive and takes much longer than a power plant fueled by natural gas. The Union of Concerned Scientists, which says it is not against nuclear power in principle, said in an earlier analysis of the AP1000 that its simplified design \"is far less vulnerable than existing reactors to a total loss of AC power\" during an accident. \"As a result, risk assessments by the designers find that the probability that these reactors will experience a severe accident is much lower. For example, these analyses show that the probability of a core meltdown is 100 times lower than that for today’s plants. But the group added that \"little experience with full-scale reactors operating at full power is available to validate computer models of these safety systems, producing significant uncertainties.\"