Westinghouse Electric Company, which helped drive the development of nuclear energy and the electric grid itself, filed for bankruptcy protection on Wednesday, casting a shadow over the global nuclear industry. The filing comes as the company’s corporate parent, Toshiba of Japan, scrambles to stanch huge losses stemming from Westinghouses troubled nuclear construction projects in the American South. Now, the future of those projects, which once seemed to be on the leading edge of a renaissance for nuclear energy, is in doubt. This is a fairly big and consequential deal, said Richard Nephew, a senior research scholar at the Center on Global Energy Policy at Columbia University. You’ve had some power companies and big utilities run into financial trouble, but this kind of thing hasn’t happened. Westinghouse, a once-proud name that in years past symbolized Americas supremacy in nuclear power, now illustrates its problems. Many of the companys injuries are self-inflicted, such as a disastrous deal for a construction business that was intended to control costs and instead precipitated the events that led to the filing on Wednesday. Over all, Toshiba has been widely criticized for overpaying for Westinghouse. But some of what went wrong was beyond either companys control. Slowing demand for electricity and tumbling prices for natural gas have eroded the economic rationale for nuclear power, which is extremely costly and technically challenging to develop. Alternative-energy sources like wind and solar power are rapidly maturing and coming down in price. The 2011 earthquake in Japan that led to the nuclear disaster at the Fukushima Daiichi plant renewed worries about safety.