San Luis Obispo Mothers for Peace v. Nuclear Regulatory Commission , 449 F.3d 1016 ( 2006 )


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  •                     FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    SAN LUIS OBISPO MOTHERS FOR               
    PEACE; SANTA LUCIA
    CHAPTER OF THE SIERRA CLUB; PEG
    PINARD,
    Petitioners,                No. 03-74628
    NRC No.
    
    PACIFIC GAS AND ELECTRIC
    COMPANY,                                           CLI-03-01;
    Intervenor,                 CLI-02-23
    v.                                 OPINION
    NUCLEAR REGULATORY COMMISSION;
    UNITED STATES OF AMERICA,
    Respondents.
    
    On Petition for Review of an Order of the
    Nuclear Regulatory Commission
    Argued and Submitted
    October 17, 2005—San Francisco, California
    Filed June 2, 2006
    Before: Stephen Reinhardt and Sidney R. Thomas,
    Circuit Judges, and Jane A. Restani,* Chief Judge,
    United States Court of International Trade
    Opinion by Judge Thomas
    *The Honorable Jane A. Restani, Chief Judge, United States Court of
    International Trade, sitting by designation.
    6063
    SAN LUIS OBISPO MOTHERS v. NRC               6067
    COUNSEL
    Diane Curran, Harmon, Curran, Spielberg & Eisenberg,
    L.L.P., Washington, D.C., for the petitioners.
    Charles E. Mullins, United States Nuclear Regulatory Com-
    mission, Washington, D.C., for the respondents.
    David A. Repka, Winston & Strawn, L.L.P., Washington,
    D.C., for respondent-intervenor PG&E.
    Sheldon L. Trubatch, Esq., Offices of Robert K. Temple,
    Esq., Chicago, Illinois, for amicus San Luis Obispo County.
    Kevin James, California Department of Justice, Oakland, Cal-
    ifornia, for amicus States of California, Massachusetts, Utah
    and Washington.
    Jay E. Silberg, Shaw Pittman, L.L.P., Washington, D.C., for
    amicus Nuclear Energy Institute.
    OPINION
    THOMAS, Circuit Judge:
    This case presents the question, inter alia, as to whether the
    likely environmental consequences of a potential terrorist
    6068           SAN LUIS OBISPO MOTHERS v. NRC
    attack on a nuclear facility must be considered in an environ-
    mental review required under the National Environmental
    Policy Act. The United States Nuclear Regulatory Commis-
    sion (“NRC”) contends that the possibility of a terrorist attack
    on a nuclear facility is so remote and speculative that the
    potential consequences of such an attack need not be consid-
    ered at all in such a review. The San Luis Obispo Mothers for
    Peace and other groups disagree and petition for review of the
    NRC’s approval of a proposed Interim Spent Fuel Storage
    Installation. We grant the petition in part and deny it in part.
    I
    The NRC is an independent federal agency established by
    the Energy Reorganization Act of 1974 to regulate the civilian
    use of nuclear materials. Intervenor Pacific Gas and Electric
    Company (“PG&E”) filed an application with the NRC under
    10 C.F.R. Part 72 for a license to construct and operate an
    Interim Spent Fuel Storage Installation (“Storage Installation”
    or “ISFSI”) at PG&E’s Diablo Canyon Power Plant (“Diablo
    Canyon”) in San Luis Obispo, California. The NRC granted
    the license. The question presented by this petition for review
    is whether, in doing so, the NRC complied with federal stat-
    utes including the National Environmental Policy Act of 1969
    (“NEPA”), 
    42 U.S.C. §§ 4321-4437
    , the Atomic Energy Act
    of 1954 (“AEA”), 
    42 U.S.C. §§ 2011
    -2297g, and the Admin-
    istrative Procedure Act (“APA”), 
    5 U.S.C. §§ 551-706
    .
    NEPA establishes a “national policy [to] encourage produc-
    tive and enjoyable harmony between man and his environ-
    ment,” and was intended to reduce or eliminate environmental
    damage and to promote “the understanding of the ecological
    systems and natural resources important to” the United States.
    Dept. of Transp. v. Pub. Citizen, 
    541 U.S. 752
    , 756 (2004)
    (quoting 
    42 U.S.C. § 4321
    ). The Supreme Court has identified
    NEPA’s “twin aims” as “plac[ing] upon an agency the obliga-
    tion to consider every significant aspect of the environmental
    impact of a proposed action[, and] ensur[ing] that the agency
    SAN LUIS OBISPO MOTHERS v. NRC                 6069
    will inform the public that it has indeed considered environ-
    mental concerns in its decisionmaking process.” Baltimore
    Gas & Elec. Co. v. Natural Res. Def. Counsel, Inc., 
    462 U.S. 87
    , 97 (1983).
    Rather than mandating particular results, NEPA imposes on
    federal agencies procedural requirements that force consider-
    ation of the environmental consequences of agency actions.
    Pub. Citizen, 
    541 U.S. at 756
    . At NEPA’s core is the require-
    ment that federal agencies prepare an environmental impact
    statement (“EIS”), or:
    include in every recommendation or report on pro-
    posals for legislation and other major Federal actions
    significantly affecting the quality of the human envi-
    ronment, a detailed statement by the responsible offi-
    cial on—(i) the environmental impact of the
    proposed action, (ii) any adverse environmental
    effects which cannot be avoided should the proposal
    be implemented, (iii) alternatives to the proposed
    action, (iv) the relationship between local short-term
    uses of man’s environment and the maintenance and
    enhancement of long-term productivity, and (v) any
    irreversible and irretrievable commitments of
    resources which would be involved in the proposed
    action should it be implemented.
    
    Id. at 757
     (quoting 
    42 U.S.C. § 4332
    (2)(C)).
    As an alternative to the EIS, an agency may prepare a more
    limited environmental assessment (“EA”) concluding in a
    “Finding of No Significant Impact” (“FONSI”), briefly pre-
    senting the reasons why the action will not have a significant
    impact on the human environment. 
    Id.
     at 757-58 (citing 
    40 C.F.R. §§ 1501.4
    (e), 1508.13). If, however, the EA does not
    lead to the conclusion that a FONSI is warranted, the agency
    remains obligated to prepare an EIS. 
    Id. at 757
    .
    6070          SAN LUIS OBISPO MOTHERS v. NRC
    While NEPA requires the NRC to consider environmental
    effects of its decisions, the AEA is primarily concerned with
    setting minimum safety standards for the licensing and opera-
    tion of nuclear facilities. The NRC does not contest that the
    two statutes impose independent obligations, so that compli-
    ance with the AEA does not excuse the agency from its
    NEPA obligations. The AEA lays out the process for consid-
    eration of the public health and safety aspects of nuclear
    power plant licensing, and requires the NRC to determine
    whether the licensing and operation of a proposed facility is
    “in accord with the common defense and security and will
    provide adequate protection to the health and safety of the
    public.” 
    42 U.S.C. § 2232
    (a).
    The NRC is not, however, required to make this determina-
    tion without assistance; federal law provides a framework for
    hearings on material issues that interested persons raise by
    specific and timely petition. 
    42 U.S.C. § 2239
    (a); 
    10 C.F.R. §§ 2.308
    -.348; 
    5 U.S.C. §§ 551-706
    . The initial hearing is
    held before a three-person Atomic Safety and Licensing
    Board (“Licensing Board”). 
    10 C.F.R. § 2.321
    . The Licensing
    Board’s findings and decision constitute the agency’s initial
    determination, although a party may file a petition for review
    with the Commission within 15 days of the Licensing Board’s
    decision. 
    10 C.F.R. § 2.341
    . If the petition is granted, the
    Commission specifies the issues to be reviewed and the par-
    ties to the review proceedings, 
    10 C.F.R. § 2.341
    (c)(1), and
    renders a final decision. 
    10 C.F.R. § 2.344
    . A party may then
    petition this court for review of the Commission’s final deci-
    sion. 
    28 U.S.C. § 2344
    .
    II
    With this general statutory background, we turn to the facts
    underlying the petition for review. On December 21, 2001,
    PG&E applied to the NRC pursuant to 10 C.F.R. Part 72 for
    a license to construct and operate a Storage Installation at
    Diablo Canyon. The Storage Installation would permit the
    SAN LUIS OBISPO MOTHERS v. NRC                       6071
    necessary and on-site storage of spent fuel, the byproduct of
    the two nuclear reactors at that site. PG&E expects to fill its
    existing spent fuel storage capacity at Diablo Canyon some-
    time this year. Therefore, unless additional spent fuel storage
    capacity is created, the Diablo Canyon reactors cannot con-
    tinue to function beyond 2006.
    PG&E proposes to build a dry cask storage facility. The
    basic unit of the storage system is the Multi-Purpose Canister
    (“Canister”), a stainless steel cylinder that is filled with radio-
    active waste materials and welded shut. The Canisters are
    loaded into concrete storage overpacks that are designed to
    permit passive cooling via the circulation of air. The storage
    casks, or the filled Canisters loaded into overpacks, are then
    placed on one of seven concrete pads. The Storage Installation
    would house a total of 140 storage casks, 2 more than the 138
    projected to be required for storage of spent fuel generated at
    Diablo Canyon through 2025.
    On April 22, 2002, the NRC published a Notice of Oppor-
    tunity for Hearing. Under the regulatory scheme, interested
    parties could then request a hearing or petition for leave to
    intervene. 
    10 C.F.R. § 2.309
    (a). A written hearing request,
    which must contain the contentions the party wants litigated
    at the hearing, will be granted if the petitioner has standing,
    and has posed at least one admissible contention.1 
    Id.
    On July 19, 2002, the San Luis Obispo Mothers for Peace,
    a non-profit corporation concerned with Diablo Canyon’s
    1
    In order to be admissible, a contention must: be set forth with particu-
    larity, 
    10 C.F.R. § 2.309
    (f)(1); provide a specific statement of the disputed
    issue of law or fact, 
    10 C.F.R. § 2.309
    (f)(1)(i); provide the basis for the
    contention, 
    10 C.F.R. § 2.309
    (f)(1)(ii); demonstrate that the issue is within
    the scope of the proceeding, 
    10 C.F.R. § 2.309
    (f)(1)(iii); demonstrate that
    the issue is material to the findings the NRC must make, 
    10 C.F.R. § 2.309
    (f)(1)(iv); provide supporting references and expert opinions, 
    10 C.F.R. § 2.309
    (f)(1)(v); and provide sufficient information to show the
    existence of a genuine issue of law or fact, 
    10 C.F.R. § 2.309
    (f)(1)(vi).
    6072             SAN LUIS OBISPO MOTHERS v. NRC
    local impact, the Sierra Club, a non-profit corporation con-
    cerned with national environmental policy, and Peg Pinard, an
    individual citizen, (collectively “Petitioners”) submitted a
    hearing request and a petition to intervene, asserting conten-
    tions for admission.
    In Licensing Board Proceeding LBP-02-23, 56 NRC 413
    (“LBP 02-23”), the Atomic Safety and Licensing Board
    addressed the admissibility of the July 19 petition’s five Tech-
    nical and three Environmental Contentions.2 One Technical
    Contention, TC-1, dealing with the state of PG&E’s finances,
    was deemed admissible; the acceptance of at least one conten-
    tion meant that the petition was granted. Although the Licens-
    ing Board deemed two Environmental Contentions, EC-1,
    dealing with the failure to address environmental impacts of
    terrorist or other acts of malice or insanity, and EC-3, dealing
    with the failure to evaluate environmental impacts of trans-
    portation of radioactive materials3 inadmissible, the Licensing
    Board nonetheless referred the final ruling as to the admissi-
    bility of these two contentions to the NRC, “in light of the
    2
    Technical Contention Number One (“TC-1”) alleged Inadequate Seis-
    mic Analysis. TC-2 alleged PG&E’s Financial Qualifications Are Not
    Demonstrated. TC-3 alleged PG&E May Not Apply for a License for a
    Third Party. TC-4 alleged Failure to Establish Financial Relationships
    Between Parties Involved in Construction and Operation of Installation.
    TC-5 alleged Failure to Provide Sufficient Description of Construction
    and Operation Costs. Environmental Contention Number One (“EC-1”)
    alleged Failure to Address Environmental Impacts of Destructive Acts of
    Malice or Insanity. EC-2 alleged Failure to Fully Describe Purposes of
    Proposed Action or to Evaluate All Reasonably Associated Environmental
    Impacts and Alternatives. EC-3 alleged Failure to Evaluate Environmental
    Impacts of Transportation.
    3
    Because the Storage Installation is not a permanent repository, this
    contention assumes the eventual transport of the materials stored there to
    a permanent site. Among the materials submitted to support the contention
    were some dealing with possible terrorist or other malicious attacks on the
    spent fuel while in transit. The ruling on the contention was “referr[ed]
    . . . to the Commission to the extent terrorism and sabotage matters are
    proffered in support of its admission.” 56 NRC at 453.
    SAN LUIS OBISPO MOTHERS v. NRC                   6073
    Commission’s ongoing ‘top to bottom’ review of the agency’s
    safeguards and physical security programs.” 56 NRC at 448.
    In a memorandum and order, CLI-03-1, 57 NRC 1 (“CLI
    03-01”), the NRC accepted the Licensing Board’s referral of
    its decision to reject the environmental contentions related to
    terrorism. Although the Commission affirmed the Licensing
    Board’s rejection of the contentions, it based its decision on
    a different rationale. The NRC relied on four prior decisions
    in which it held that the NEPA does not require a terrorism
    review.4 These decisions, most particularly Private Fuel Stor-
    age, CLI-02-25, 56 NRC 340 (2002), outlined four reasons
    for this holding: (1) the possibility of terrorist attack is too far
    removed from the natural or expected consequences of agency
    action to require study under NEPA; (2) because the risk of
    a terrorist attack cannot be determined, the analysis is likely
    to be meaningless; (3) NEPA does not require a “worst-case”
    analysis; and (4) NEPA’s public process is not an appropriate
    forum for sensitive security issues. The NRC concluded:
    Our decision today rests entirely on our understand-
    ing of NEPA and of what means are best suited to
    dealing with terrorism. Nonetheless, our conclusion
    comports with the practical realities of spent fuel
    storage and the congressional policy to encourage
    utilities to provide for spent fuel storage at reactor
    sites pending construction of a permanent repository.
    Storage of spent fuel at commercial reactor sites
    offers no unusual technological challenges. Indeed,
    it has been occurring at Diablo Canyon for many
    4
    Those cases include: Private Fuel Storage, L.L.C., CLI-02-25, 56 NRC
    340 (2002) (Storage Installation); Duke Cogema Stone & Webster (Mixed
    Oxide Fuel Fabrication Facility), CLI-02-24, 56 NRC 335 (2002); Domin-
    ion Nuclear Connecticut, Inc. (Nuclear Power Station), CLI-02-27, 56
    NRC 367 (2002); and Duke Energy Corp. (Nuclear Power Station), CLI-
    02-26, 56 NRC 358 (2002). All four cases were decided on December 18,
    2002.
    6074             SAN LUIS OBISPO MOTHERS v. NRC
    years and will continue whether or not we license the
    proposed Installation.
    57 NRC at 7.
    In September of 2002, prior to the NRC’s decision on the
    first petition, Petitioners submitted a second petition, this time
    requesting suspension of the Storage Installation licensing
    proceeding pending comprehensive review of the adequacy of
    Diablo Canyon’s design and operation measures for protec-
    tion against terrorist attack and other acts of malice or insan-
    ity. Unlike the July 19 petition, this one addressed security
    measures for the entire Diablo Canyon complex, not merely
    the Storage Installation. Petitioners explained that 
    10 C.F.R. § 2.335
    , which prohibits challenges to any NRC rule or regu-
    lation in an adjudicatory proceeding involving initial or
    renewal licensing, prevented the raising of contentions con-
    testing the adequacy of NRC safety requirements protecting
    against terrorist or other malicious attacks on the entire com-
    plex in the July 19 Petition. Petitioners also stated that 
    10 C.F.R. § 72.32
     prevented them from raising emergency plan-
    ning contentions in the earlier petition. Thus, Petitioners
    insisted that the second petition “d[id] not constitute a request
    for rulemaking, nor . . . for enforcement action,” and instead
    defined it, without reference to any particular hearing-
    granting provision of the regulations, as “a request for actions
    that are necessary to ensure that any licensing decision made
    by the Commission with respect to the proposed Diablo Can-
    yon Installation complies with the Commission’s statutory
    obligations under the Atomic Energy Act.”
    In a memorandum and order, CLI-02-23, 56 NRC 230
    (“CLI 02-23”), the NRC denied the September 2002 petition.
    Because the petition did not, according to the NRC, “fit com-
    fortably in any specific category, [the Commission] treat[ed]
    it as a general motion brought under the procedural require-
    ments of 
    10 C.F.R. § 2.730
    .”5 In rejecting the petition, the
    5
    Since renumbered as 
    10 C.F.R. § 2.323
    , this regulation provides, sim-
    ply, for “motions”.
    SAN LUIS OBISPO MOTHERS v. NRC              6075
    Commission reasoned that by not suspending operating
    licenses at installations and power plants following the Sep-
    tember 11, 2001 terrorist attacks, it had demonstrated its
    implicit conclusion that the continued operation of these facil-
    ities neither posed an imminent risk to the public health, nor
    was inimical to the common defense. Further, the Commis-
    sion concluded that because it had already initiated a thorough
    review of its safeguards and physical security program, there
    was no reason to suspend the Diablo Canyon licensing pro-
    ceeding to address the terrorism-related concerns raised by the
    Petitioners. It stated that “[t]here certainly is no reason to
    believe that any danger to public health and safety would
    result from mere continuation of this adjudicatory proceed-
    ing,” given that the proceeding was in its initial stages, that
    construction was not scheduled to begin for several years, and
    that the Petitioners would be able to comment on any changes
    in the rules resulting from the Commission’s ongoing review
    of terrorism-related matters if and when they were to occur.
    In a memorandum and order, CLI-03-12, 58 NRC 185
    (2003) (“CLI 03-02”), the NRC denied the petitions for
    agency review of the Licensing Board’s decisions that “cumu-
    latively, rejected challenges to [the PG&E] Installation appli-
    cation.” This denial thus became a final order, reviewable by
    this court on petition for review. 
    28 U.S.C. § 2344
    .
    In October of 2003, the Spent Fuel Project Office of the
    NRC’s Office of Material Safety and Safeguards released its
    Environmental Assessment Related to the Construction and
    Operation of the Diablo Canyon Independent Spent Fuel Stor-
    age Installation. The 26-page document contains the NRC’s
    conclusion “that the construction, operation, and decommis-
    sioning of the Diablo Canyon Installation will not result in
    significant impact to the environment,” and therefore that “an
    [EIS] is not warranted for the proposed action, and pursuant
    to 10 C.F.R. [§] 51.31, a Finding of No Significant Impact is
    appropriate.”
    6076           SAN LUIS OBISPO MOTHERS v. NRC
    The EA is not devoid of discussion of terrorist attacks.
    Indeed, the document contains the Commission’s response to
    a comment submitted by the California Energy Commission
    in response to an earlier draft that “there is no discussion in
    the EA of the potential destruction of the casks or blockage
    of air inlet ducts as the result of sabotage or a terrorist attack
    . . . [nor is there] a description of how decisions are being
    made regarding the configuration, design and spacing of the
    casks, the use of berms, and the location of the ISFSI to mini-
    mize the vulnerability of the ISFSI to potential attack.” The
    NRC responded:
    In several recent cases, . . . the Commission has
    determined that an NRC environmental review is not
    the appropriate forum for the consideration of terror-
    ist acts. The NRC staff considers the security of
    spent fuel as part of its safety review of each applica-
    tion for an ISFSI license. In addition to reviewing an
    ISFSI application against the requirements of 10
    CFR Part 72, the NRC staff evaluates the proposed
    security plans and facility design features to deter-
    mine whether the requirements in 10 CFR Part 73,
    “Physical Protection of Plants and Materials,” are
    met. The details of specific security measures for
    each facility are Safeguards Information, and as
    such, can not be released to the public.
    The NRC has also initiated several actions to fur-
    ther ensure the safety of spent fuel in storage. Addi-
    tional security measures have been put in place at
    nuclear facilities, including ISFSIs currently storing
    spent fuel. These measures include increased secur-
    ity patrols, augmented security forces and weapons,
    additional security posts, heightened coordination
    with law enforcement and military authorities, and
    additional limitations on vehicular access. Also, as
    part of its comprehensive review of its security pro-
    gram, the NRC is conducting several technical
    SAN LUIS OBISPO MOTHERS v. NRC                  6077
    studies to assess potential vulnerabilities of spent
    fuel storage facilities to a spectrum of terrorist acts.
    The results of these studies will be used to determine
    if revisions to the current NRC security requirements
    are warranted.
    Petitioners argue that, in denying their petitions, the NRC
    violated the AEA, the APA, and NEPA. Although we reject
    the AEA and APA claims, we agree with Petitioners that the
    agency has failed to comply with NEPA. We have jurisdiction
    over those final orders of the NRC made reviewable by 
    42 U.S.C. § 2239
    , which includes final orders entered in licens-
    ing proceedings, under 
    28 U.S.C. § 2342
    (4).
    III
    We turn first to Petitioners’ AEA argument. Specifically,
    Petitioners argue that the NRC violated its regulations imple-
    menting the AEA, as well as the AEA’s hearing provisions,
    when it denied Petitioners a hearing on whether NEPA
    required consideration of the environmental impact of a ter-
    rorist attack on the Storage Installation; they also argue that
    the NRC violated the AEA’s hearing provisions in denying
    Petitioners a hearing on post-September 11th security mea-
    sures for the entire Diablo Canyon complex. Both of these
    challenges fail.
    A
    [1] The NRC did not violate the AEA or its implementing
    regulations when it failed to explain its rejection of Petition-
    ers’ contentions by addressing each of their arguments. Noth-
    ing in the regulations or the AEA requires the NRC to provide
    such an explanation.
    Section 189(a) of the AEA grants public hearing rights
    “upon the request of any person whose interest may be affect-
    ed” by an NRC licensing proceeding. 
    42 U.S.C. § 2239
    . The
    6078            SAN LUIS OBISPO MOTHERS v. NRC
    NRC public hearing regulations, at 
    10 C.F.R. § 2.309
    , “pro-
    mulgated pursuant to the AEC’s6 power to make, promulgate,
    issue, rescind, and amend such rules and regulations as may
    be necessary to carry out the purposes of” the AEA, 
    12 U.S.C. § 2201
    (p), specify the procedures required of both petitioners
    and the NRC in making and deciding hearing petitions.
    [2] Petitioners correctly observe that the NRC, in its deci-
    sion, did not discuss whether Petitioners satisfied the regula-
    tory standard. They are mistaken, however, in their
    unsupported contention that this omission amounts to the
    agency’s failure to follow its own regulations and thus is “re-
    versible error.” The regulations simply do not require the
    NRC to explain its decisions in any particular manner.
    Although the NRC regulations are specific and demanding in
    what they require of petitioners, they demand far less of the
    NRC in responding to a petition: the regulations require only
    a timely “decision.” See 
    10 C.F.R. § 2.714
    (i) (“Decision on
    request/petition. The presiding officer shall, within 45 days
    after the filing of answers and replies . . . issue a decision on
    each request for hearing/petition to intervene.”). Because Peti-
    tioners do not claim that the NRC violated this requirement,
    we must reject this challenge.
    B
    [3] The NRC’s denial of a hearing on whether NEPA
    requires consideration of the environmental effects of a terror-
    ist attack on the Storage Installation did not violate the AEA’s
    hearing provisions.
    [4] Petitioners contend that the NRC relied on an improper
    ground in denying their request for a hearing on whether
    6
    In 1974, Congress eliminated the Atomic Energy Commission
    (“AEC”). Regulatory functions went to the NRC, and promotional func-
    tions to the Energy Research and Development Administration. See
    Energy Reorganization Act of 1974, 
    42 U.S.C. § 5814
    .
    SAN LUIS OBISPO MOTHERS v. NRC               6079
    NEPA requires the Commission to consider the environmen-
    tal impacts of terrorism — namely, the ground that it had
    determined in earlier decisions that NEPA imposes no such
    obligation. Thus, Petitioners do not challenge the substantive
    validity or coherence of those earlier opinions in making their
    AEA claim, but rather the reliance upon a prior determination
    of the merits in order to reject a petition presenting the same
    issues. As such, Sierra Club v. NRC, 
    862 F.2d 222
     (9th Cir.
    1988), on which Petitioners rely, does not apply. In that case,
    the NRC rejected the petitioners’ contentions as lacking in
    reasonable specificity, and yet went on to analyze the merits
    of those supposedly unacceptable contentions. 
    Id. at 228
    .
    Here, however, where the agency is rejecting the contentions
    as contrary to a prior decision, the “merits” and the reason for
    the inadmissibility of the contention collapse. Put differently,
    the NRC did not reach the merits of the petition as much as
    it assessed the issues raised against issues resolved by prior
    decisions. We hold that in doing so, the Commission com-
    plied fully with the AEA. To hold otherwise would unduly
    restrict the agency’s evaluation of hearing petitions, by requir-
    ing it to grant a hearing on issues it has already resolved
    whenever a petitioner claims to have new evidence. We can
    find, and Petitioners point to, nothing in the AEA that would
    require this result.
    C
    [5] The NRC’s denial of a hearing on security measures for
    Diablo Canyon as a whole also did not violate the AEA. Peti-
    tioners argue that the AEA requires the NRC to grant petition-
    ers a hearing on all issues of material fact, including the
    security of the entire Diablo Canyon complex. Petitioners
    therefore conclude, citing Union of Concerned Scientists v.
    NRC, 
    735 F.2d 1437
     (D.C. Cir. 1984), that the NRC violated
    the AEA when it denied a hearing on that issue.
    Petitioners’ argument misreads Union of Concerned Scien-
    tists, in which the D.C. Circuit held only that the agency can-
    6080           SAN LUIS OBISPO MOTHERS v. NRC
    not by rule presumptively eliminate a material issue from
    consideration in a hearing petition. Union of Concerned Sci-
    entists requires the agency to consider a petition; it does not
    require that the agency grant it.
    The NRC in CLI 02-23 did not deny that security require-
    ments for the entire complex might need to be upgraded, but
    rather maintained that a licensing proceeding hearing (and one
    regarding an installation, not the entire complex) was not the
    correct forum in which to address the issue. The Commission
    directed Petitioners to participate in a rulemaking or to raise
    their concerns in a hearing then pending before the Licensing
    Board. Petitioners contend that these alternative fora are illu-
    sory, and that rejection of their petition amounted to the
    denial of any opportunity to participate in the consideration of
    post-9/11 security measures for the Diablo Canyon complex.
    Petitioners argue “[i]f the NRC were going to resolve Peti-
    tioners’ concerns that grossly inadequate security made the
    Diablo Canyon facility vulnerable to terrorist attacks generi-
    cally, through a rulemaking, such a rulemaking would have
    been initiated as a result of the ‘comprehensive security
    review’ undertaken by the NRC.” Thus, Petitioners argue that
    it would have been futile to submit a rulemaking petition.
    This argument must fail, as Petitioners did not use the avail-
    able procedures for initiating a rulemaking. Petitioners cannot
    complain that NRC failed to institute a rulemaking they never
    requested.
    [6] Given that rulemaking may have been an avenue for
    Petitioners’ participation, had they chosen to pursue it, their
    argument that they had no forum in which to raise their con-
    tentions loses its force. However, even were Petitioners cor-
    rect in their assertion that they were unfairly denied the
    opportunity to participate in a rulemaking proceeding, the
    argument that the Licensing Board hearing was similarly illu-
    sory would fail. In fact, Petitioners were attempting to use the
    present Storage Installation licensing proceeding as a means
    SAN LUIS OBISPO MOTHERS v. NRC             6081
    of launching a much broader challenge to the Diablo Canyon
    complex. The NRC correctly observes that a petition alleging
    that existing NRC regulations are “grossly inadequate to pro-
    tect against terrorist attack, and therefore must be supple-
    mented by additional requirements” cannot in fact be raised
    before the Licensing Board, which cannot hear challenges to
    NRC rules. The limited scope of licensing proceedings does
    not, however, amount to the arbitrary denial of a forum, as
    Petitioners claim. While Petitioners could have raised site-
    specific issues “relating to the ‘common defense and securi-
    ty’ ” that were not controlled by existing rules or regulations
    to the Licensing Board, they are not entitled to expand those
    proceedings to include the entire complex, and issues already
    covered by agency rules.
    D
    In short, the NRC did not violate the AEA in denying the
    petitions for a hearing. Neither the AEA nor its implementing
    regulations required the NRC to grant Petitioners a hearing on
    whether NEPA required a consideration of the environmental
    impact of a terrorist attack on the Storage Installation or the
    security measures adopted for the entire Diablo Canyon com-
    plex.
    IV
    [7] The NRC’s reliance on its own prior opinions in its
    decision in this case does not violate the APA’s notice and
    comment provisions. Petitioners argue that the decisions in
    CLI 03-01 and PFS amount to the announcement “of a gen-
    eral policy of refusing to consider the environmental impacts
    of terrorist attacks in Environmental Impact Statements.” Peti-
    tioners rely on Mada-Luna v. Fitzpatrick, 
    813 F.2d 1006
    ,
    1014 (9th Cir. 1987) to claim that this policy depends on fac-
    tual determinations not found subsequent to an evidentiary
    proceeding, and constitutes a “binding substantive norm,” the
    promulgation of which, without a public hearing, violates the
    6082             SAN LUIS OBISPO MOTHERS v. NRC
    APA notice and comment provisions contained in 
    5 U.S.C. §§ 553
    (b), (c).7 The flaw in Petitioners’ argument is the mis-
    taken assertion that the NRC’s decisions were factual and not
    legal. If the NRC’s conclusion that terrorism need not be
    examined under NEPA were factual, then Petitioners would
    be correct that its determination would have to comply with
    APA rulemaking requirements, including notice and com-
    ment, or else the agency would have to permit petitioners to
    challenge it in every proceeding where it was disputed.
    [8] That NEPA does not require consideration of the envi-
    ronmental impacts of terrorism is a legal, and not a factual,
    conclusion. Cf. Greenpeace Action v. Franklin, 
    14 F.3d 1324
    ,
    1331 (9th Cir. 1993) (reasoning that a challenge to the ade-
    quacy of an EA turned on factual, not legal, principles where
    both NEPA’s applicability and the requirements it imposed
    were uncontested); see also Alaska Wilderness Recreation &
    Tourism Ass’n v. Morrison, 
    67 F.3d 723
    , 727 (9th Cir. 1995)
    (noting that although “challenges to agency actions which
    raise predominantly legal, rather than technical questions, are
    rare,” the court was there required to address “just such a
    challenge”). Petitioners’ analysis is therefore inapposite. The
    agency has the discretion to use adjudication to establish a
    binding legal norm. See Sec. & Exch. Comm’n v. Chenery,
    
    332 U.S. 194
    , 199-203 (1947) (“[T]he choice made between
    proceeding by general rule or by individual, ad hoc litigation,
    is one that lies primarily in the informed discretion of the
    administrative agency.”). We therefore agree with the NRC’s
    characterization in its brief to this court: having come to the
    legal conclusion that NEPA does not require consideration of
    the environmental consequences of terrorist attacks, “[w]hen
    
    7 U.S.C. § 553
    (b) states that “[g]eneral notice of proposed rulemaking
    shall be published in the Federal Register,” and outlines the requirements
    that such notice must meet. 
    5 U.S.C. § 553
    (c) states that after such notice
    has been given, “the agency shall give interested persons an opportunity
    to participate in the rulemaking through submission of written data, views,
    or arguments with or without opportunity for oral presentation.”
    SAN LUIS OBISPO MOTHERS v. NRC               6083
    petitioners in this case presented a proposed contention seek-
    ing an EIS that analyzed the impacts of possible terrorist acts
    at the proposed Diablo Canyon Installation, the NRC reason-
    ably concluded that this request was sufficiently similar to the
    request in PFS to justify the application of that decision here.”
    V
    Although we hold that the agency did not violate the APA
    when it relied on the prior resolution of a legal issue through
    adjudication, we come to a different conclusion as to that
    determination’s compliance with NEPA. Because the issue
    whether NEPA requires consideration of the environmental
    impacts of a terrorist attack is primarily a legal one, we
    review the NRC’s determination that it does not for reason-
    ableness. See Alaska Wilderness Recreation & Tourism Ass’n,
    
    67 F.3d at 727
     (reviewing predominately legal issue for rea-
    sonableness because “it makes sense to distinguish the strong
    level of deference we accord an agency in deciding factual or
    technical matters from that to be accorded in disputes involv-
    ing predominately legal questions”); Ka Makani’o Kohala
    Ohana, Inc. v. Water Supply, 
    295 F.3d 955
    , 959 n.3 (9th Cir.
    2002) (“Because this case involved primarily legal issues . . .
    based on undisputed historical facts, we conclude that the
    ‘reasonableness’ standard should apply to this case.”).
    Here, the NRC decided categorically that NEPA does not
    require consideration of the environmental effects of potential
    terrorist attacks. In making this determination, the NRC relied
    on PFS, where it “consider[ed] in some detail the legal ques-
    tion whether NEPA requires an inquiry into the threat of ter-
    rorism at nuclear facilities.” 56 NRC 340, 343 (2002). In that
    case, intervenor State of Utah filed a contention claiming that
    the September 11 terrorist attacks “had materially changed the
    circumstances under which the Board had rejected previously
    proffered terrorism contentions by showing that a terrorist
    attack is both more likely and potentially more dangerous
    than previously thought.” Id. at 345. The NRC concluded that
    6084           SAN LUIS OBISPO MOTHERS v. NRC
    even following the September 11th attacks, NEPA did not
    impose such a requirement, reasoning:
    In our view, an EIS is not an appropriate format to
    address the challenges of terrorism. The purpose of
    an EIS is to inform the decisionmaking authority and
    the public of a broad range of environmental impacts
    that will result, with a fair degree of likelihood, from
    a proposed project, rather than to speculate about
    ‘worst-case’ scenarios and how to prevent them.
    Id. at 347.
    The NRC determined that four grounds “cut[ ] against
    using the NEPA framework” to consider the environmental
    effects of a terrorist attack: (1) the possibility of a terrorist
    attack is far too removed from the natural or expected conse-
    quences of agency action; (2) because the risk of a terrorist
    attack cannot be determined, the analysis is likely to be mean-
    ingless; (3) NEPA does not require a “worst-case” analysis;
    and (4) NEPA’s public process is not an appropriate forum for
    sensitive security issues. Id. at 348. We review each of these
    four grounds for reasonableness, and conclude that these
    grounds, either individually or collectively, do not support the
    NRC’s categorical refusal to consider the environmental
    effects of a terrorist attack.
    A
    [9] The Commission relied first on finding that the possibil-
    ity of a terrorist attack is too far removed from the natural or
    expected consequences of agency action. Id. at 347. Section
    102 of NEPA requires federal agencies to prepare “a detailed
    statement . . . on the environmental impact” of any proposed
    major federal action “significantly affecting the quality of the
    human environment.” 
    42 U.S.C. § 4332
    (1)(C)(i). The ques-
    tion thus becomes whether a given action “significantly
    affects” the environment.
    SAN LUIS OBISPO MOTHERS v. NRC                6085
    The NRC claims that the appropriate analysis of Section
    102 is that employed by the Supreme Court in Metropolitan
    Edison Co. v. People Against Nuclear Power, 
    460 U.S. 766
    ,
    773 (1983). In Metropolitan Edison, the Court noted that “[t]o
    determine whether Section 102 requires consideration of a
    particular effect, we must look to the relationship between
    that effect and the change in the physical environment caused
    by the major federal action at issue,” looking for “a reason-
    ably close causal relationship . . . like the familiar doctrine of
    proximate cause from tort law.” 
    460 U.S. at 774
    . The Com-
    mission claims that its conclusion that the environmental
    impacts of a possible terrorist attack on an NRC-licensed
    facility is beyond a “reasonably close causal relationship” was
    a reasonable application of this “proximate cause” analogy.
    The problem with the agency’s argument, however, is that
    Metropolitan Edison and its proximate cause analogy are
    inapplicable here. In Metropolitan Edison, the petitioners
    argued that NEPA required the NRC to consider the potential
    risk of psychological damage upon reopening the Three Mile
    Island nuclear facilities to those in the vicinity. Noting that
    NEPA is an environmental statute, the Supreme Court held
    that the essential analysis must focus on the “closeness of the
    relationship between the change in the environment and the
    ‘effect’ at issue.” 
    460 U.S. at 772
    .
    The appropriate analysis is instead that developed by this
    court in NoGwen Alliance v. Aldridge, 
    855 F.2d 1380
     (9th
    Cir. 1988). In NoGwen, the plaintiffs argued that NEPA
    required the Air Force to consider the threat of nuclear war in
    the implementation of the Ground Wave Emergency Network
    (“GWEN”). We held “that the nexus between construction of
    GWEN and nuclear war is too attenuated to require discussion
    of the environmental impacts of nuclear war in an [EA] or
    [EIS].” 
    855 F.2d at 1386
    .
    [10] The events at issue here, as well as in Metropolitan
    Edison and NoGwen, form a chain of three events: (1) a major
    6086           SAN LUIS OBISPO MOTHERS v. NRC
    federal action; (2) a change in the physical environment; and
    (3) an effect. Metropolitan Edison was concerned with the
    relationship between events 2 and 3 (the change in the physi-
    cal environment, or increased risk of accident resulting from
    the renewed operation of a nuclear reactor, and the effect, or
    the decline in the psychological health of the human popula-
    tion). The Court in Metropolitan Edison explicitly distin-
    guished the case where the disputed relationship is between
    events 1 and 2: “we emphasize that in this case we are consid-
    ering effects caused by the risk of accident. The situation
    where an agency is asked to consider effects that will occur
    if a risk is realized, for example, if an accident occurs . . . is
    an entirely different case.” 
    Id.
     at 775 n.9. In NoGwen, we fol-
    lowed the Court’s admonition and, in addressing the relation-
    ship between events 1 and 2, we held that the Metropolitan
    Edison analysis did not apply “because it discusse[d] a differ-
    ent type of causation than that at issue in this case . . . [which]
    require[d] us to examine the relationship between the agency
    action and a potential impact on the environment.” 
    Id. at 1386
    . NoGWEN relied on our decision in Warm Springs Dam
    Task Force v. Gribble, 
    621 F.2d 1017
    , 1026 (9th Cir. 1980),
    which held that “an impact statement need not discuss remote
    and highly speculative consequences.” Applying that standard
    to the plaintiffs’ claims that the military GWEN system’s
    installation would “increase the probability of nuclear war,”
    and “that GWEN would be a primary target in a nuclear war,”
    we held both propositions to be “remote and highly specula-
    tive,” and, therefore, NEPA did not require their consider-
    ation.
    [11] In the present case, as in NoGwen, the disputed rela-
    tionship is between events 1 and 2 (the federal act, or the
    licensing of the Storage Installation, and the change in the
    physical environment, or the terrorist attack). The appropriate
    inquiry is therefore whether such attacks are so “remote and
    highly speculative” that NEPA’s mandate does not include
    consideration of their potential environmental effects.
    SAN LUIS OBISPO MOTHERS v. NRC                6087
    [12] The NRC responds by simply declaring without sup-
    port that, as a matter of law, “the possibility of a terrorist
    attack . . . is speculative and simply too far removed from the
    natural or expected consequences of agency action to require
    a study under NEPA.” 56 NRC at 349. In doing so, the NRC
    failed to address Petitioners’ factual contentions that licensing
    the Storage Installation would lead to or increase the risk of
    a terrorist attack because (1) the presence of the Storage
    Installation would increase the probability of a terrorist attack
    on the Diablo Canyon nuclear facility, and (2) the Storage
    Installation itself would be a primary target for a terrorist
    attack. We conclude that it was unreasonable for the NRC to
    categorically dismiss the possibility of terrorist attack on the
    Storage Installation and on the entire Diablo Canyon facility
    as too “remote and highly speculative” to warrant consider-
    ation under NEPA.
    [13] In so concluding, we also recognize that the NRC’s
    position that terrorist attacks are “remote and highly specula-
    tive,” as a matter of law, is inconsistent with the government’s
    efforts and expenditures to combat this type of terrorist attack
    against nuclear facilities. In the PFS opinion, the NRC
    emphasized the agency’s own post-September 11th efforts
    against the threat of terrorism:
    At the outset, however, we stress our determination,
    in the wake of the horrific September 11th terrorist
    attacks, to strengthen security at facilities we regu-
    late. We currently are engaged in a comprehensive
    review of our security regulations and programs, act-
    ing under our AEA-rooted duty to protect “public
    health and safety” and the “common defense and
    security.” We are reexamining, and in may cases
    have already improved, security and safeguards mat-
    ters such as guard force size, physical security exer-
    cises, clearance requirements and background
    investigations for key employees, and fitness-for-
    duty requirements. More broadly, we are rethinking
    6088              SAN LUIS OBISPO MOTHERS v. NRC
    the NRC’s threat assessment framework and design
    basis threat. We also are reviewing our own infra-
    structure, resources, and communications.
    Our comprehensive review may also yield perma-
    nent rule or policy changes that will apply to the pro-
    posed PFS facility and to other NRC-related
    facilities. The review process is ongoing and cumu-
    lative. It has already resulted in a number of
    security-related actions to address terrorism threats
    at both active and defunct nuclear facilities.
    56 NRC at 343. Among these actions is the establishment of
    an Office of Nuclear Security and Incident Response, “re-
    sponsible for immediate operational security and safeguards
    issues as well as for long-term policy development[,] work[-
    ing] closely with law enforcement agencies and the Office of
    Homeland Security[,] . . . coordinat[ing] the NRC’s ongoing
    comprehensive security review.” Id. at 344-45.
    We find it difficult to reconcile the Commission’s conclu-
    sion that, as a matter of law, the possibility of a terrorist attack
    on a nuclear facility is “remote and speculative,” with its
    stated efforts to undertake a “top to bottom” security review
    against this same threat. Under the NRC’s own formulation of
    the rule of reasonableness, it is required to make determina-
    tions that are consistent with its policy statements and proce-
    dures. Here, it appears as though the NRC is attempting, as a
    matter of policy, to insist on its preparedness and the serious-
    ness with which it is responding to the post-September 11th
    terrorist threat, while concluding, as a matter of law, that all
    terrorist threats are “remote and highly speculative” for NEPA
    purposes.8
    8
    The view that a terrorist attack is too speculative to be a required part
    of NEPA review would seem to be inconsistent with the NRC’s pre-9/11
    security procedures. Since 1977, the NRC has required licensed plants to
    have a security plan that is designed to protect against a “design basis
    SAN LUIS OBISPO MOTHERS v. NRC                      6089
    [14] In sum, in considering the policy goals of NEPA and
    the rule of reasonableness that governs its application, the
    possibility of terrorist attack is not so “remote and highly
    speculative” as to be beyond NEPA’s requirements.
    B
    [15] The NRC’s reliance upon the second PFS factor, that
    the Risk of a Terrorist Attack Cannot be Adequately Deter-
    mined, 56 NRC at 350, is also not reasonable. First, the
    NRC’s dismissal of the risk of terrorist attacks as “unquantifi-
    able” misses the point. The numeric probability of a specific
    attack is not required in order to assess likely modes of attack,
    weapons, and vulnerabilities of a facility, and the possible
    impact of each of these on the physical environment, includ-
    ing the assessment of various release scenarios. Indeed, this
    is precisely what the NRC already analyzes in different con-
    texts. It is therefore possible to conduct a low probability-high
    consequence analysis without quantifying the precise proba-
    bility of risk. The NRC itself has recognized that consider-
    ation of uncertain risks may take a form other than
    quantitative “probabilistic” assessment. In its “Proposed Pol-
    icy Statement on Severe Accidents and Related Views on
    Nuclear Reactor Regulation,” 48 Fed.Reg. 16,014 (1983), the
    Commission stated that:
    threat” for radiological sabotage. See General Accounting Office, Nuclear
    Regulatory Commission: Oversight of Security at Commercial Nuclear
    Power Plants Needs to be Strengthened, GAO-030752 (2003) at 6. “The
    design basis threat characterizes the elements of a postulated attack,
    including the number of attackers, their training, and the weapons and tac-
    tics they are capable of using.” Id.
    Thus, the NRC—even before the terrorist attacks of 9/11—did not con-
    sider such attacks too “remote and speculative” to be considered in agency
    planning. To the contrary, the agency has long required analysis of means
    and methods of hypothetical attacks against specific facilities, with the
    goal of establishing effective counter-measures.
    6090           SAN LUIS OBISPO MOTHERS v. NRC
    In addressing potential accident initiators (including
    earthquakes, sabotage, and multiple human errors)
    where empirical data are limited and residual uncer-
    tainty is large, the use of conceptual modeling and
    scenario assumptions in Safety Analysis Reports will
    be helpful. They should be based on the best quali-
    fied judgments of experts, either in the form of sub-
    jective numerical probability estimates or qualitative
    assessments of initiating events and casual [sic]
    linkages in accident sequences.
    48 Fed.Reg. at 16,020 (emphasis added).
    [16] No provision of NEPA, or any other authority cited by
    the Commission, allows the NRC to eliminate a possible envi-
    ronmental consequence from analysis by labeling the risk as
    “unquantifiable.” See Limerick Ecology Action, Inc. v. NRC,
    
    869 F.2d 719
    , 754 (3rd Cir. 1989) (J. Scirica, dissenting)
    (finding no “statutory provision, no NRC regulation or policy
    statement, and no case law that permits the NRC to ignore any
    risk found to be unquantifiable”). If the risk of a terrorist
    attack is not insignificant, then NEPA obligates the NRC to
    take a “hard look” at the environmental consequences of that
    risk. The NRC’s actions in other contexts reveal that the
    agency does not view the risk of terrorist attacks to be insig-
    nificant. Precise quantification is therefore beside the point.
    Even if we accept the agency’s argument, the agency fails
    to adequately show that the risk of a terrorist act is unquantifi-
    able. The agency merely offers the following analysis as to
    the quantifiability of a potential terrorist attack:
    The horrors of September 11 notwithstanding, it
    remains true that the likelihood of a terrorist attack
    being directed at a particular nuclear facility is not
    quantifiable. Any attempt at quantification or even
    qualitative assessment would be highly speculative.
    In fact, the likelihood of attack cannot be ascertained
    SAN LUIS OBISPO MOTHERS v. NRC                        6091
    with confidence by any state-of-the-art methodology.
    That being the case, we have no means to assess,
    usefully, the risks of terrorism at the PFS facility.
    56 NRC at 350. The agency nonetheless has simultaneously
    shown the ability to conduct a “top to bottom” terrorism
    review. This leaves the Commission in the tenuous position
    of insisting on the impossibility of a meaningful, i.e. quantifi-
    able, assessment of terrorist attacks, while claiming to have
    undertaken precisely such an assessment in other contexts.
    Further, as we have noted, the NRC has required site-specific
    analysis of such threats, involving numerous recognized scenar-
    ios.9
    [17] Thus, we conclude that precise quantification of a risk
    is not necessary to trigger NEPA’s requirements, and even if
    it were, the NRC has not established that the risk of a terrorist
    attack is unquantifiable.
    C
    The NRC’s third ground, that it is not required to conduct
    a “worst-case” analysis, is a non sequitur. Although it is a true
    statement of the law, the agency errs in equating an assess-
    ment of the environmental impact of terrorist attack with a
    demand for a worst-case analysis.
    The Council on Environmental Quality (“CEQ”) regula-
    tions, 
    40 C.F.R. §§ 1500.1
     - 1518.4, promulgated with the
    “purpose [of] tell[ing] federal agencies what they must do to
    comply with [NEPA] procedures and achieve the goals of
    9
    The NRC’s assertion that a risk of terrorism cannot be quantified is
    also belied by the very existence of the Department of Homeland Security
    Advisory System, which provides a general assessment of the risk of ter-
    rorist attacks. See, e.g., World Market Research Centre, Global Terrorism
    Index 2003/4 (offering a probabilistic risk assessment of terrorist activities
    over a 12-month period).
    6092           SAN LUIS OBISPO MOTHERS v. NRC
    [NEPA],” have been interpreted by the Supreme Court as “en-
    titled to substantial deference.” Robertson v. Methow Valley
    Citizens Council, 
    490 U.S. 332
    , 355 (citing Andrus v. Sierra
    Club, 
    442 U.S. 347
    , 358 (1979)). These regulations mandated
    worst-case analyses until 1986, when CEQ replaced the for-
    mer 
    40 C.F.R. § 1502.22
    , requiring an agency, when relevant
    information was either unavailable or too costly to obtain, to
    include in the EIS a “worst-case analysis and an indication of
    the probability or improbability of its occurrence,” with the
    new and current version of the regulation, which requires an
    agency to instead deal with uncertainties by including within
    the EIS “a summary of existing credible scientific evidence
    which is relevant to evaluating the reasonable foreseeable sig-
    nificant adverse impacts on the human environment, and . . .
    the agency’s evaluation of such impacts based upon theoreti-
    cal approaches or research methods generally accepted in the
    scientific community.” 
    40 C.F.R. §§ 1502.22
    (b)(3), (4). The
    current requirement applies to those events with potentially
    catastrophic consequences “even if their probability of occur-
    rence is low, provided that the analysis of impacts is sup-
    ported by credible scientific evidence, is not based on pure
    conjecture, and is within the rule of reason.” 
    40 C.F.R. § 1502.22
     (b)(4). The Supreme Court held in Robertson that
    the amendment of the regulations had nullified the worst-case
    analysis requirement. 
    490 U.S. at 355
    ; Edwardsen v. U.S.
    Dep’t of Interior, 
    268 F.3d 781
    , 785 (9th Cir. 2001).
    The Commission is therefore correct when it argues that
    NEPA does not require a worst-case analysis. It is mistaken,
    however, when it claims that “Petitioners’ request for an anal-
    ysis of [the environmental effects of] a successful terrorist
    attack at the Diablo Canyon ISFSI approximates a request for
    a ‘worst-case’ analysis that has long since been discarded by
    the CEQ regulations . . . and discredited by the Federal
    courts.” According to the NRC, “[m]aking the various
    assumptions required by [P]etitioners’ scenario requires the
    NRC to venture into the realm of ‘pure conjecture.’ ” We dis-
    agree.
    SAN LUIS OBISPO MOTHERS v. NRC                      6093
    [18] An indication of what CEQ envisioned when it
    imposed the worst-case analysis requirement can be gleaned
    from a 1981 CEQ memorandum, Forty Most Asked Questions
    Concerning CEQ’s National Environmental Policy Act Regu-
    lations, reprinted at 46 FR 18026-01 (March 23, 1981). CEQ
    answered one of those questions, “[w]hat is the purpose of a
    worst-case analysis? How is it formulated and what is the
    scope of the analysis?” with the following:
    The purpose of the analysis is to . . . cause agencies
    to consider th[ ]e potential consequences [of agency
    decisions] when acting on the basis of scientific
    uncertainties or gaps in available information. The
    analysis is formulated on the basis of available infor-
    mation, using reasonable projections of the worst
    possible consequences of a proposed action.
    For example, if there are scientific uncertainty and
    gaps in the available information concerning the
    numbers of juvenile fish that would be entrained in
    a cooling water facility, the responsible agency must
    disclose and consider the possibility of the loss of
    the commercial or sport fishery. In addition to an
    analysis of a low probability/catastrophic impact
    event, the worst-case analysis should also include a
    spectrum of events of higher probability but less
    drastic impact.
    46 FR 18026, 18032. While it is true that the agency is not
    required to consider consequences that are “speculative,”10 the
    10
    Because we disagree with the agency’s interpretation of worst-case
    analysis, we do not reach the agency’s characterization of the possibility
    of terrorist attack as “speculative.” We note, however, that this character-
    ization stands out as contrary to the vigilant stance that Americans are
    encouraged to take by the Department of Homeland Security. See
    www.dhs.gov/dhspublic/display?theme=29 (urging that “[a]ll Americans
    should continue to be vigilant” and noting that “[t]he country remains at
    an elevated risk . . . for terrorist attack.”)
    6094           SAN LUIS OBISPO MOTHERS v. NRC
    NRC’s argument wrongly labels a terrorist attack the worst-
    case scenario because of the low or indeterminate probability
    of such an attack. The CEQ memo, by including as worst-case
    scenarios events of both higher and lower probability, reveals
    that worst-case analysis is not defined solely by the low prob-
    ability of the occurrence of the events analyzed, but also by
    the range of outcomes of those events. See also Greater Yel-
    lowstone Coalition v. Flowers, 
    321 F.3d 1250
    , 1260 (10th
    Cir. 2003) (citing a witness’s testimony that the loss of bald
    eagle nesting sites was both “likely” and “a worst-case sce-
    nario”). Petitioners do not seek to require the NRC to analyze
    the most extreme (i.e., the “worst”) possible environmental
    impacts of a terrorist attack. Instead, they seek an analysis of
    the range of environmental impacts likely to result in the
    event of a terrorist attack on the Storage Installation. We
    reject the Commission’s characterization of this request as a
    demand for a worst-case analysis.
    D
    [19] The NRC’s reliance on the fourth PFS factor, that it
    cannot comply with its NEPA mandate because of security
    risks, is also unreasonable. There is no support for the use of
    security concerns as an excuse from NEPA’s requirements.
    While it is true, as the agency claims, that NEPA’s require-
    ments are not absolute, and are to be implemented consistent
    with other programs and requirements, this has never been
    interpreted by the Supreme Court as excusing NEPA’s appli-
    cation to a particularly sensitive issue. See Weinberger v.
    Catholic Action of Hawaii, 
    454 U.S. 139
     (1981) (holding that
    the Navy was required to perform a NEPA review and to fac-
    tor its results into decisionmaking even where the sensitivity
    of the information involved meant that the NEPA results
    could not be publicized or adjudicated). Weinberger can sup-
    port only the proposition that security considerations may per-
    mit or require modification of some of the NEPA procedures,
    not the Commission’s argument that sensitive security issues
    result in some kind of NEPA waiver.
    SAN LUIS OBISPO MOTHERS v. NRC              6095
    The application of NEPA’s requirements, under the rule of
    reason relied on by the NRC, is to be considered in light of
    the two purposes of the statute: first, ensuring that the agency
    will have and will consider detailed information concerning
    significant environmental impacts; and, second, ensuring that
    the public can both contribute to that body of information, and
    can access the information that is made public. Pub. Citizen,
    
    541 U.S. at 768
    . To the extent that, as the NRC argues, certain
    information cannot be publicized, as in Weinberger, other
    statutory purposes continue to mandate NEPA’s application.
    For example, that the public cannot access the resulting infor-
    mation does not explain the NRC’s determination to prevent
    the public from contributing information to the decisionmak-
    ing process. The NRC simply does not explain its unwilling-
    ness to hear and consider the information that Petitioners seek
    to contribute to the process, which would fulfill both the
    information-gathering and the public participation functions
    of NEPA. These arguments explain why a Weinberger-style
    limited proceeding might be appropriate, but cannot support
    the NRC’s conclusion that NEPA does not apply. As we
    stated in NoGWEN : “There is no ‘national defense’ exception
    to NEPA . . . ‘The Navy, just like any federal agency, must
    carry out its NEPA mandate to the fullest extent possible and
    this mandate includes weighing the environmental costs of the
    [project] even though the project has serious security implica-
    tions.’ ” 
    855 F.2d at 1384
     (quoting Concerned About Trident
    v. Rumsfeld, 
    555 F.2d 817
    , 823 (D.C. Cir. 1977)).
    E
    [20] In sum, none of the four factors upon which the NRC
    relies to eschew consideration of the environmental effects of
    a terrorist attack satisfies the standard of reasonableness. We
    must therefore grant the petition in part and remand for the
    agency to fulfill its responsibilities under NEPA.
    [21] Our identification of the inadequacies in the agency’s
    NEPA analysis should not be construed as constraining the
    6096           SAN LUIS OBISPO MOTHERS v. NRC
    NRC’s consideration of the merits on remand, or circumscrib-
    ing the procedures that the NRC must employ in conducting
    its analysis. There remain open to the agency a wide variety
    of actions it may take on remand, consistent with its statutory
    and regulatory requirements. We do not prejudge those alter-
    natives. Nor do we prejudge the merits of the inquiry. We
    hold only that the NRC’s stated reasons for categorically
    refusing to consider the possibility of terrorist attacks cannot
    withstand appellate review based on the record before us.
    We are also mindful that the issues raised by the petition
    may involve questions of national security, requiring sensitive
    treatment on remand. However, the NRC has dealt with our
    nation’s most sensitive nuclear secrets for many decades, and
    is well-suited to analyze the questions raised by the petition
    in an appropriate manner consistent with national security.
    VI
    We deny the petition as to the claims under the AEA and
    the APA. However, because we conclude that the NRC’s
    determination that NEPA does not require a consideration of
    the environmental impact of terrorist attacks does not satisfy
    reasonableness review, we hold that the EA prepared in reli-
    ance on that determination is inadequate and fails to comply
    with NEPA’s mandate. We grant the petition as to that issue
    and remand for further proceedings consistent with this opin-
    ion.
    PETITION GRANTED IN PART; DENIED IN PART;
    REMANDED.