The Westinghouse Electric Company filed for bankruptcy protection on Wednesday, in a major blow to the nuclear power industry. The Chapter 11 filing came as Westinghouse reported huge cost overruns in its efforts to build new nuclear reactors in South Carolina and Georgia. Regulators are now questioning whether the plants will ever be completed. Westinghouse technology is used in more than half the world’s nuclear power plants. The company’s bankruptcy comes as the cost of electricity from solar and wind farms continues to drop.