The U.S. Nuclear Regulatory Commission said yesterday that it was not responsible for evaluating the potential environmental impacts of a terrorist attack on a proposed nuclear-waste storage facility in western Utah. Opponents of the $3.1 billion facility, which would be located about 45 miles southwest of Salt Lake City on sovereign lands belonging to Skull Valley Goshute Indians, received a second blow when the NRC also determined, in a separate ruling, that it does have the authority to license private storage sites for spent nuclear fuel. The state of Utah, which currently has no nuclear storage facilities, has opposed the project from the beginning, but the Atomic Safety and Licensing Board, which conducts independent legal and scientific reviews for the NRC, has rejected more than two dozen of the state’s concerns. Utah’s legal advisors were not immediately sure whether they would appeal the latest rulings.