with whom Justice Stevens joins, concurring in part and concurring in the judgment.
I join the Court’s opinion, except to the extent it suggests that a State may not prohibit the construction of nuclear powerplants if the State is motivated by concerns about the safety of such plants. Since the Court finds that California was not so motivated, this suggestion is unnecessary to the *224Court’s holding. More important, I believe the Court’s dictum is wrong in several respects.
The Court takes the position that a State’s safety-motivated decision to prohibit construction of nuclear power-plants would be pre-empted for three distinct reasons. First, the Court states that “the Federal Government has occupied the entire field of nuclear safety concerns, except the limited powers expressly ceded to the States.” Ante, at 212. Second, the Court indicates that “a state judgment that nuclear power is not safe enough to be further developed would conflict squarely with the countervailing judgment of the NRC . . . that nuclear construction may proceed notwithstanding extant uncertainties as to waste disposal.” Ante, at 213. Third, the Court believes that a prohibition on construction of new nuclear plants would “be in the teeth of the Atomic Energy Act’s objective to insure that nuclear technology be safe enough for widespread development and use.” Ibid. For reasons summarized below, I cannot agree that a State’s nuclear moratorium, even if motivated by safety concerns, would be pre-empted on any of these grounds.
I
First, Congress has occupied not the broad field of “nuclear safety concerns,” but only the narrower area of how a nuclear plant should be constructed and operated to protect against radiation hazards.1 States traditionally have possessed the authority to choose which technologies to rely on in meeting their energy needs. Nothing in the Atomic Energy Act limits this authority, or intimates that a State, in exercising this authority, may not consider the features that distinguish nuclear plants from other power sources. On the contrary, § 271 of the Act, 68 Stat. 960, as amended, 42 U. S. C. § 2018, indicates that States may continue, with respect to nuclear *225power, to exercise their traditional police power over the manner in which they meet their energy needs. There is, in short, no evidence that Congress had a “clear and manifest purpose,” Rice v. Santa Fe Elevator Corp., 331 U. S. 218, 230 (1947), to force States to be blind to whatever special dangers are posed by nuclear plants.
Federal pre-emption of the States’ authority to decide against nuclear power would create a regulatory vacuum. See Wiggins, Federalism Balancing and the Burger Court: California’s Nuclear Law as a Preemption Case Study, 13 U. C. D. L. Rev. 3, 64 (1979). In making its traditional policy choices about what kinds of power are best suited to its needs, a State would be forced to ignore the undeniable fact that nuclear power entails certain risks. While the NRC does evaluate the dangers of generating nuclear power, it does not balance those dangers against the risks, costs, and benefits of other choices available to the State or consider the State’s standards of public convenience and necessity. As Professor Wiggins noted:
“If a state utility regulatory agency like California’s Energy Commission is prevented from making a general evaluation of feasibility, on broad grounds of social, economic and ideological policy, then the decision whether to build a nuclear facility in a state will ultimately be made only by the public utility seeking its construction. . . . It would be ironic if public energy utilities, granted a jurisdictional monopoly in large part because of their heavy regulation by the state, were freed from regulatory oversight of the one decision which promises to affect the greatest number of persons over the greatest possible time.” Ibid, (emphasis in original).
In short, there is an important distinction between the threshold determination whether to permit the construction of new nuclear plants and, if the decision is to permit construction, the subsequent determinations of how to construct *226and operate those plants. The threshold decision belongs to the State; the latter decisions are for the NRC. See Note, May A State Say “No” to Nuclear Power? Pacific Legal Foundation Gives a Disappointing Answer, 10 Envir. L. 189, 199 (1979) (criticizing District Court decision in the present case).
II
The Court’s second basis for suggesting that States may not prohibit the construction of nuclear plants on safety grounds is that such a prohibition would conflict with the NRC’s judgment that construction of nuclear plants may safely proceed. A flat ban for safety reasons, however, would not make “compliance with both federal and state regulations ... a physical impossibility.” Florida Lime & Avocado Growers, Inc. v. Paul, 373 U. S. 132, 142-143 (1963). The NRC has expressed its judgment that it is safe to proceed with construction and operation of nuclear plants, but neither the NRC nor Congress has mandated that States do so.2 See ante, at 205.
III
A state regulation' also conflicts with federal law if it “stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.” Hines v. Davidowitz, 312 U. S. 52, 67 (1941). The Court suggests that a safety-motivated state ban on nuclear plants would be pre-empted under this standard as well. See ante, at 213, 221-222.3 But Congress has merely encouraged the develop*227ment of nuclear technology so as to make another source of energy available to the States; Congress has not forced the States to accept this particular source. See Note, 10 Envir. L., at 199 (“Congress has not evidenced a dictatorial intent for every state to build nuclear power plants”). A ban on nuclear plant construction for safety reasons thus does not conflict with Congress’ objectives or purposes.
The Atomic Energy Act was intended to promote the technological development of nuclear power, at a time when there was no private nuclear power industry. The Act addressed “the practical question of bringing such an industry into being,”4 in order to make available an additional energy source. The Court makes much of the general statements of purpose in the Act and the legislative history, see ante, at 221, but those statements simply reflect Congress’ desire to create a private nuclear power industry. Congress did not compel States to give preference to the eventual product of that industry or to ignore the peculiar problems associated with that product. See Wiggins, 13 U. C. D. L. Rev., at 78.
More recent legislation makes it very clear that there is no federal policy preventing a State from choosing to rely on technologies it considers safer than nuclear power. The Energy Reorganization Act of 1974, 88 Stat. 1233, 42 U. S. C. *228§ 5801 et seq. (1976 ed. and Supp. V), separated promotional and regulatory functions in the area of nuclear power. The Act established the NRC to perform the regulatory and licensing functions of the Atomic Energy Commission, § 5841, and the Energy Research and Development Administration (ERDA) to “develop, and increase the efficiency and reliability of use of, all energy sources.” § 5801(a).5 The legislative history of the Act expresses concern about a pronuclear bias in the regulatory agency and demonstrates a desire to have the Federal Government “place greater relative emphasis on nonnuclear energy.” S. Rep. No. 93-980, p. 14 (1974).6
This legislative purpose is consistent with the fact that States retain many means of prohibiting the construction of nuclear plants within their borders. States may refuse to issue certificates of public convenience and necessity for individual nuclear powerplants. They may establish siting and land use requirements for nuclear plants that are more stringent than those of the NRC. Cf. NRC Authorization Act for Fiscal 1980, Pub. L. 96-295, § 108(f), 94 Stat. 783. Under the Clean Air Act Amendments of 1977, States may regulate radioactive air emissions from nuclear plants and may impose more stringent emission standards than those promulgated by the NRC. 42 U. S. C. §§ 7416, 7422 (1976 ed., Supp. V). This authority may be used to prevent the construction of nuclear plants altogether. Consolidated Edison Co. of New York, Inc. (Indian Point Station, Unit No. 2), ALAB-453, 7 N. R. C. 31, 34, and n. 13 (1978).
*229In sum, Congress has not required States to “go nuclear,” in whole or in part. The Atomic Energy Act’s twin goals were to promote the development of a technology and to ensure the safety of that technology. Although that Act reserves to the NRC decisions about how to build and operate nuclear plants, the Court reads too much into the Act in suggesting that it also limits the States’ traditional power to decide what types of electric power to utilize. Congress simply has made the nuclear option available, and a State may decline that option for any reason. Rather than rest on the elusive test of'legislative motive, therefore, I would conclude that the decision whether to build nuclear plants remains with the States. In my view, a ban on construction of nuclear powerplants would be valid even if its authors were motivated by fear of a core meltdown or other nuclear catastrophe.
The Court recognizes the limited nature of the federal role, ante, at 205, but then describes that role in more expansive terms, ante, at 212-213.
A conflict would exist, of course, if the NRC determined that construction of nuclear plants could not proceed and a State nevertheless chose to go ahead with construction. Cf. Florida Lime & Avocado Growers, Inc. v. Paul, 373 U. S., at 143.
The Court states that such a ban would be “in the teeth of the Atomic Energy Act’s objective to insure that nuclear technology be safe enough for widespread development and use.” Ante, at 213. A State’s decision not to permit construction of nuclear plants, however, affects only indirectly the Atomic Energy Act’s goal of ensuring that nuclear power be safe enough *227for widespread development. A safety-motivated ban might highlight a State’s perception that the federal safety goal had not been accomplished, but the ban itself would not interfere with efforts to achieve that goal.
The Court apparently believes the Atomic Energy Act’s actual purpose was to maximize the use of nuclear power to satisfy the Nation’s needs. A moratorium on construction of nuclear plants would prevent the accomplishment of this goal, but, as demonstrated infra, the Court is incorrect in attributing this goal to Congress. Moreover, the degree to which a nuclear moratorium hampers achievement of the goal does not depend on the motives of its framers.
Address by Congressman Cole, Chairman of Joint Committee on Atomic Energy, delivered at International Congress on Nuclear Engineering (June 24, 1954), quoted in Lemov, State and Local Control Over the Location of Nuclear Reactors Under the Atomic Energy Act of 1954, 39 N. Y. U. L. Rev. 1008, 1018 (1964).
In 1977, ERDA’s functions were transferred to the Department of Energy. 91 Stat. 677, 42 U. S. C. § 7151(a) (1976 ed., Supp. V).
In subsequent legislation Congress has continued to promote many sources of energy, without giving preference to nuclear power. See, e. g., Powerplant and Industrial Fuel Use Act of 1978, 92 Stat. 3291, 42 U. S. C. § 8301 et seq. (1976 ed., Supp. V) (encouraging greater use of coal and other alternative fuels in lieu of natural gas and petroleum); Public Utility Regulatory Policies Act of 1978, § 210, 92 Stat. 3144, 16 U. S. C. § 824a-3 (1976 ed., Supp. V) (encouraging development of cogeneration and small power production facilities).