The federal Atomic Energy Commission has exclusive jurisdiction to license the transfer, delivery, receipt, acquisition, possession, and use of nuclear materials. The Commission does not, have authority over the generation of electricity itself, or over the economic question whether a particular plant should be built. This case emerges from the intersection of the federal government's efforts to ensure that nuclear power is safe with the exercise of the historic state authority over the generation and sale of electricity. A California law imposes a moratorium on the certification of nuclear energy plants until the State Commission 'finds that there has been developed and that the United States through its authorized agency has approved and there exists a demonstrated technology or means for the disposal of high-level nuclear waste.' In 1978, petitioners Pacific Gas & Electric Co. and Southern California Edison Co. filed this action claiming that the California statute is invalid under the Supremacy Clause because they are preempted by the Atomic Energy Act. On the merits, the court held that the nuclear moratorium provisions of § 25524.2 were not preempted because §§ 271 and 274(k) of the Atomic Energy Act, 42 U.S.C. §§ 2018 and 2021(k), constitute a congressional authorization for States to regulate nuclear power plants 'for purposes other than protection against radiation hazards.' The court held that § 25524.2 was not designed to provide protection against radiation hazards, but was adopted because 'uncertainties in the nuclear fuel cycle make nuclear power an uneconomical and uncertain source of energy.' The Supreme Court granted certiorari limited to the question of whether §§ 25524.1(b) and 25524.2 are ripe for judicial review, and whether they are preempted by the Atomic Energy Act.