United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued November 19, 2012               Decided May 14, 2013

                        No. 12-1106

  BLUE RIDGE ENVIRONMENTAL DEFENSE LEAGUE, ET AL.,
                    PETITIONERS

                              v.

   NUCLEAR REGULATORY COMMISSION AND THE UNITED
                STATES OF AMERICA,
                   RESPONDENTS

         WESTINGHOUSE ELECTRIC COMPANY LLC,
                    INTERVENORS


                 Consolidated with 12-1151


          On Petition for Review of Orders of the
       United States Nuclear Regulatory Commission


     Diane Curran argued the cause for petitioners. With her
on the briefs were Mindy Goldstein and John Runkle.
    Robert M. Rader, Senior Attorney, U.S. Nuclear
Regulatory Commission, argued the cause for respondents.
With him on the brief were J. David Gunter II, Trial Attorney,
U.S. Department of Justice, John F. Cordes, Jr., Solicitor,
                               2
U.S. Nuclear Regulatory Commission, and Jeremy M.
Suttenberg, Attorney.
    Randall L. Speck, David L. Cousineau, M. Stanford
Blanton, Millicent W. Ronnlund, and Kathryn M. Sutton were
on the brief for intervenors Westinghouse Electric Company
LLC, et al., in support of respondents.
    Before: BROWN, Circuit Judge, and EDWARDS and
SILBERMAN, Senior Circuit Judges.
     EDWARDS, Senior Circuit Judge: This case arises from
actions taken by the Nuclear Regulatory Commission (“NRC”
or “Commission”) approving (1) an application by Southern
Nuclear Operating Company (“Southern”) for combined
licenses to construct and operate new Units 3 and 4 of the
Vogtle Nuclear Power Plant and (2) an application by
Westinghouse Electric Company (“Westinghouse”) for an
amendment to its already-approved AP1000 reactor design on
which the Vogtle application relied. In approving the
applications, NRC applied the regulatory scheme incorporated
in 10 C.F.R. Part 52 covering the licensing of commercial
nuclear power reactors. See Nuclear Info. Res. Serv. v. NRC,
969 F.2d 1169, 1170 (D.C. Cir. 1992) (en banc) (upholding
two-part regulatory scheme in 10 C.F.R. Part 52).
     In 2009, after a contested evidentiary hearing in which
Petitioners participated, NRC granted Southern an early site
permit for Vogtle Units 3 and 4. In 2008, Southern applied for
combined licenses. A second contested proceeding was held
in which Petitioners participated. The application for the early
site permit was supported by an Environmental Impact
Statement (“EIS”); the application for combined licenses was
supported by the initial EIS and an updated EIS. After the
close of the combined-license hearing record, Petitioners
sought to reopen the hearing to litigate contentions relating to
the nuclear accident at the Fukushima Dai-ichi complex in
                              3
Japan on March 11, 2011. In the wake of the Fukushima
accident, NRC commissioned a Task Force to reevaluate
nuclear safety regulations in the United States. Petitioners
unsuccessfully sought to forestall the licensing of the Vogtle
reactors and the approval of the modified AP1000 design until
NRC had fully considered and implemented the Task Force
recommendations.
     After the Task Force recommendations were issued and
approved by NRC, Petitioners pursued various actions to
compel the agency to supplement its EIS and to delay any
action on the combined license and AP1000 design
rulemaking proceedings until after the agency had
implemented the Task Force recommendations. Petitioners
contended, inter alia, that Vogtle’s EIS violated the National
Environmental Policy Act (“NEPA”), 42 U.S.C. §§ 4321-
4347, because it did not address allegedly new and significant
environmental implications of the Task Force’s
recommendations after Fukushima. NRC ruled that
Petitioners’ challenges were premature, that the agency’s
existing procedural mechanisms were sufficient to ensure
licensees’ compliance with not-yet-enacted regulatory
safeguards, and that the licensing and rulemaking proceedings
could continue without delay. NRC further held that
Petitioners had failed to satisfy the contention-specificity
requirements of 10 C.F.R. § 2.309(f)(1), which state that the
proponents of contentions must indicate with specificity the
claims they wish to litigate. See Union of Concerned
Scientists v. NRC, 920 F.2d 50, 51-52 (D.C. Cir. 1990). NRC
also held that Petitioners had failed to identify any
environmentally significant information from the Task Force
recommendations suggesting a deficiency in the Vogtle EIS.
NRC thus declined to reopen the combined-license hearing
record under 10 C.F.R. § 2.326.
                              4
     In late 2011, NRC issued its rule approving the AP1000
amended design, and in 2012 it authorized issuance of the
combined licenses. Petitioners then filed the petitions for
review giving rise to this action. Petitioners raise three
principal contentions for consideration by the court. First,
Petitioners claim that NRC abused its discretion in refusing to
reopen the hearing record in the Vogtle licensing proceeding.
Second, Petitioners assert that NRC unreasonably denied
them a right to participate in a mandatory hearing at which
NRC technical staff confirmed that the Fukushima accident
had not presented new and significant information that would
require a supplemental EIS for Vogtle. Finally, Petitioners
argue that NRC abused its discretion in approving the
AP1000 reactor design without first supplementing the
AP1000 Environmental Assessment (“EA”) that contained
important information regarding “Severe Accident Mitigation
Design Alternatives” applicable to Vogtle. Because we find
no merit in any of these contentions, we deny the petitions for
review.


           I. REGULATORY BACKGROUND
A. Reactor Design Certification
     Under 10 C.F.R. Part 52, Subpart B, a party may request
a “standard design certification” for the approval of a nuclear
power plant design. See 10 C.F.R. § 52.41. Once a design is
certified through this generic process, a future applicant may
rely on the already-approved design. See id. § 52.43(a).
Design certification by NRC requires notice-and-comment
rulemaking and culminates in publication in the Federal
Register as a “design certification rule.” See id. § 52.54.
   When a proposed design certification rule is published,
NRC’s associated EA is published for comment at the same
                               5
time. See id. § 51.31(b)(1). Because a reactor design is
certified without reference to any specific plans for its
construction, NRC has determined by rule that every
proposed design certification or amendment requires only an
EA, not a more comprehensive EIS. See id. §§ 51.31(b)(1)(i),
51.32(b)(1)-(2).
     The EA for a design certification addresses only one
topic: the costs and benefits of any Severe Accident
Mitigation Design Alternatives that were considered and not
incorporated into the final design. See id. § 51.30(d). When a
proposal is made to modify an approved design certification
rule, the amendment may rely on the EA generated for the
original design certification rule and need only consider (1)
whether the proposed design change renders any previously
rejected design alternatives cost-beneficial and (2) whether
the design change results in the identification of any new
design alternatives that necessitate a previously unperformed
cost-benefit analysis. See id. § 51.30(d). In other words,
modifications to the original EA are necessary only if the
proposed design change amendment alters the cost-benefit
calculus concerning any Severe Accident Mitigation Design
Alternatives.
B. Combined Operating Licenses
     The Atomic Energy Act authorizes NRC to issue a
combined operating license for both the construction and
operation of new reactors after a public hearing. See 42
U.S.C. § 2235(b). Any such license must be accompanied by
a full EIS, 10 C.F.R. §§ 51.75, 51.92(b), (d), (e), and may rely
on and incorporate by reference an approved standard design
certification, id. § 51.75(c)(2).
     NRC must afford interested parties an opportunity to
participate in a contested hearing subject to additional
procedural requirements. See 42 U.S.C. § 2239(a). However,
                                6
in order to initiate such a contested hearing, NRC regulations
require that interested parties submit contentions that are
supported by “sufficient information to show that a genuine
dispute exists with the applicant/licensee on a material issue
of law or fact.” 10 C.F.R. § 2.309(f)(1)(vi). In addition,
interested parties “must set forth with particularity the
contentions sought to be raised” and must:
         (ii) Provide a brief explanation of the basis for the
    contention;
         ***
         (v) Provide a concise statement of the alleged facts or
    expert opinions which support the requestor’s/petitioner’s
    position on the issue and on which the petitioner intends to
    rely . . . together with references to the specific sources and
    documents [at issue]; [and]
         ***
         (vii) In a [combined license] proceeding . . . the
    information must be sufficient, and include supporting
    information showing, prima facie, that one or more of the
    acceptance criteria in the combined license have not been
    met . . . .
Id. § 2.309(f)(1)(ii), (v), (vii). When interested parties are
allowed to intervene, “[t]he scope of the Intervenors’
participation in adjudications is limited to their admitted
contentions, i.e., they are barred from participating in the
uncontested portion of the hearing.” Exelon Generation Co.,
LLC, 62 N.R.C. 5, 49 (2005).
     NRC also holds a separate “mandatory” hearing before
issuing a combined license. See 42 U.S.C. §§ 2235(b),
2239(a); see also Exelon Generation, 62 N.R.C. at 49-50. The
mandatory hearing does not address contentions raised by the
parties, and participation is limited to the applicant and NRC
staff. See Exelon Generation, 62 N.R.C. at 49-50. The
                                7
mandatory NRC hearing determines the adequacy of the NRC
staff’s review of the application.
     Separate regulations govern when NRC must reopen a
closed hearing. See 10 C.F.R. § 2.326(a). In their briefs to this
court, the parties focused on NRC’s application of its
contention-admissibility standards, not on whether the agency
erred in declining to reopen the combined-license hearing
record. Because we find that NRC properly denied
Petitioners’ contentions, and because the standards for
reopening a closed proceeding are higher than those for
admitting a new contention, see Luminant Generation Co.,
LLC, CLI-12-07, slip op. at 14 n.47 (Mar. 16, 2012), we need
not reach the application of NRC’s reopening regulations.
C. Environmental Requirements
     NEPA mandates that a federal agency take a “hard look”
at any major undertaking by assembling an EIS. This
    ensures that the agency, in reaching its decision, will have
    available, and will carefully consider, detailed information
    concerning significant environmental impacts; it also
    guarantees that the relevant information will be made available
    to the larger audience that may also play a role in both the
    decisionmaking process and the implementation of that
    decision.
Robertson v. Methow Valley Citizens Council, 490 U.S. 332,
349 (1989). The EIS must address all reasonably foreseeable
environmental impacts, including reactor accidents, even if
the probability of such an occurrence is low. See 40 C.F.R.
§ 1502.22(b).
     As a major federal action, NRC’s issuance of a combined
operating license requires an EIS. See 10 C.F.R. § 51.20(b).
NRC regulations require preparation of an EIS both at the
early site permit stage and at the combined operating license
stage. See 10 C.F.R. § 51.75(b) (requiring EIS for early site
                              8
permit); id. § 51.75(c)(1) (requiring supplementation for
combined operating license).
    Once NRC has prepared an EIS, it must continue to
evaluate the environmental consequences of the project and
supplement the EIS, as necessary, even after initial approval.
See Marsh v. Or. Natural Res. Council, 490 U.S. 360, 370-78
(1989). This ongoing duty is mitigated, however, by a “rule of
reason,” which excuses the agency from supplementing an
environmental report based only on “remote and highly
speculative consequences.” Deukmejian v. NRC, 751 F.2d
1287, 1300 (D.C. Cir. 1984) reh’g granted and opinion
vacated on other grounds sub nom. San Luis Obispo Mothers
for Peace v. NRC, 760 F.2d 1320 (D.C. Cir. 1985) and on
reh’g sub nom. San Luis Obispo Mothers for Peace v. NRC,
789 F.2d 26 (D.C. Cir. 1986).
     The EIS must be submitted for public comment. See
TOMAC, Taxpayers of Mich. Against Casinos v. Norton, 433
F.3d 852, 861 (D.C. Cir. 2006); 40 C.F.R. § 1502.9. Although
Petitioners contend that similar public comment is mandatory
for all EAs, we have held that “the agency has significant
discretion in determining when public comment is required
with respect to EAs.” TOMAC, 433 F.3d at 861.
D. Fukushima Accident and NRC Fukushima Task
   Force
    On March 21, 2011, a catastrophic accident occurred at
the Fukushima Dai-ichi Nuclear Power Station in Honshu,
Japan. See U.S. NUCLEAR REGULATORY COMM’N,
RECOMMENDATIONS FOR ENHANCING REACTOR SAFETY IN
       ST
THE 21 CENTURY: THE NEAR-TERM TASK FORCE REVIEW OF
INSIGHTS FROM THE FUKUSHIMA DAI-ICHI ACCIDENT 7 (July
12, 2011) (“Task Force Report”). NRC appointed a Task
Force to study the regulatory implications of the accident for
the United States. The Task Force was charged to
                               9
    conduct a systematic and methodical review of U.S.
    Nuclear Regulatory Commission processes and
    regulations to determine whether the agency should make
    additional improvements to its regulatory system and to
    make recommendations to the Commission for its policy
    direction, in light of the accident at the Fukushima Dai-
    ichi Nuclear Power Plant.
Id. at vii. The Commission asked the Task Force to identify
“potential or preliminary near term/immediate operational or
regulatory issues” related to natural disasters, severe accident
mitigation, and emergency preparedness, and to propose other
improvements in light of the Fukushima accident. Union Elec.
Co., CLI-11-05, 74 N.R.C. 141, 147 (2011); see also Task
Force Report at viii.
     NRC’s Fukushima Task Force issued its report in July
2011, concluding that NRC’s “current regulatory approach,
and more importantly, the resultant plant capabilities”
demonstrate “that a sequence of events like the Fukushima
accident is unlikely to occur in the United States and some
appropriate mitigation measures have been implemented,
reducing the likelihood of core damage and radiological
releases.” Task Force Report at vii. The Task Force supported
completing work on the then-pending AP1000 design
certification rulemaking “without delay” and noted that “all of
the current early site permits [e.g., Vogtle Units 3 and 4]
already meet the requirements” of the Task Force Report
recommendation governing seismic and flooding analysis. Id.
at 71-72. In sum, the Task Force Report recommended that
both the AP1000 rulemaking and the Vogtle license
application proceedings continue without interruption.
    The Task Force offered twelve recommendations which,
“taken together are intended to clarify and strengthen the
[NRC’s] regulatory framework.” See id. at viii. The Task
Force grouped these recommendations into five categories:
                             10
“Clarifying the Regulatory Framework,” “Ensuring
Protection,” “Enhancing Mitigation,” “Strengthening
Emergency Preparedness,” and “Improving the Efficiency of
NRC Programs.” Id. at ix.
    NRC approved the Task Force’s recommendations and
urged implementation by 2016. In March 2012, NRC
implemented two Task Force recommendations, one
concerning licensees’ abilities to protect spent fuel rods in
unpredictably dangerous conditions and the other proposing
development of a new rule to upgrade “station blackout”
requirements for power failures both within and outside a
plant.


             II. FACTUAL BACKGROUND
A. AP1000 Design Certification
     NRC first issued a design certification rule approving
Westinghouse’s AP1000 design in 2006. Along with this
design certification rule, NRC prepared an EA that analyzed
sixteen Severe Accident Mitigation Design Alternatives and
rejected all sixteen on cost-benefit grounds. See
Environmental Assessment by the U.S. Nuclear Regulatory
Commission Relating to the Certification of the AP1000
Standard Plant Design, Docket No. 52-006 (2006), reprinted
in J.A. 866-902.
    Westinghouse subsequently applied for an amendment to
the approved AP1000 reactor design. NRC received and
considered over 200 public comments, most of which urged
delaying resolution of the AP1000 design amendment
proceeding until the lessons learned from the Fukushima
accident were applied to NRC regulations. See AP1000
Design Certification Amendment, 76 Fed. Reg. 82,079-01,
                               11
82,079-81 (Dec. 30, 2011) (outlining history of AP1000
design certification rule).
     On December 30, 2011, after considering these
comments, NRC declined to suspend or delay the design
certification rulemaking proceeding, emphasizing that the
AP1000 design was already compliant with many of the Task
Force recommendations. See id. NRC concluded that no
Severe Accident Mitigation Design Alternatives were cost-
beneficial and that no supplemental EA was necessary. See
Environmental Assessment by the U.S. Nuclear Regulatory
Commission Relating to Certification of the Amendment to
the AP1000 Standard Plant Design, Docket No. 52-006, 5-6
(Dec. 22, 2011), reprinted in J.A. 224-25.
    NRC certified the AP1000 design and stressed the
ongoing nature of Commission review of designs, stating that:
    even if the Commission concludes at a later time that some
    additional action is needed for the AP1000, the NRC has
    ample opportunity and legal authority to modify the AP1000
    [design certification rule] to implement NRC-required design
    changes, as well as to take any necessary action to ensure that
    holders of [combined licenses] referencing the AP1000 also
    make the necessary design changes.
AP1000 Design Certification Amendment, 76 Fed. Reg. at
82,081. As a result, NRC concluded “that no changes to the
AP1000 [design certification rule] are required at this time,”
id., and noted that the Task Force itself endorsed completion
of the AP 1000 rulemaking “without delay,” id. at 82,083.
B. Vogtle Combined Operating Licenses
     On August 15, 2006, Southern applied for an early site
permit for Vogtle Units 3 and 4. A coalition of community
action organizations, including several Petitioners in this case,
sought a hearing on the application and intervened on three
admitted contentions related to NRC’s draft EIS for the site.
                              12
NRC assigned the conduct of the licensure proceeding to a
three-member Atomic Safety and Licensing Board (“Board”),
which considered Petitioners’ contentions in a series of on-
the-record hearings. The Board ruled against Petitioners on all
three contentions, and NRC denied review, ending the
contested portion of the hearing. The Board issued its final
initial decision in August 2009, after holding its mandatory
sufficiency review and questioning Southern and NRC staff,
and approved the Vogtle early site application.
     Southern subsequently applied for combined operating
licenses for Vogtle Units 3 and 4. As with the early site
permit proceeding, NRC prepared an EIS for this licensing
action, which included consideration of the potential for
severe accidents and their consequences. See Environmental
Impacts of Postulated Accidents, Environmental Impacts of
Operation at the Vogtle Electric Generating Plant Site, § 5.10
(Mar. 2011) (“Vogtle EIS”), reprinted in J.A. 805-09;
Southern Nuclear Operating Company, Inc.; Notice of
Availability of the Final Supplemental Environmental Impact
Statement for Vogtle Electric Generating Plant Units 3 and 4;
Combined License Application Review, 76 Fed. Reg. 16,645-
02 (Mar. 24, 2011).
     In response, Petitioners brought three contentions to the
Board, which denied two and admitted the third, a safety-
related contention. After consideration of the contention, the
Board granted summary disposition against the intervenors,
finding that the contention failed to present a material factual
dispute. The Board declined to admit an additional
environmental contention and concluded the contested portion
of the proceeding. A second licensing Board was established
to consider another contention in April 2010; it denied the
request, and NRC affirmed.
    In April 2011, shortly after the Task Force was
appointed, Petitioners and other organizations submitted an
                              13
Emergency Petition, asking NRC to suspend all pending
licensing decisions, including the decision whether to issue a
combined license for Vogtle 3 and 4, while it investigated the
implications of the Fukushima accident. The Commission
denied these requests for a suspension. See generally Union
Elec. Co., CLI-11-05, 74 N.R.C. 144, 150-51, 175-76 (2011).
     At the same time, Petitioners submitted a petition
requesting that NRC immediately suspend the rulemaking for
the amendment of the AP1000 design certification pending
evaluation of the implications of the Fukushima accident. Id.
at 172-73. Petitioners asked NRC to undertake “a
comprehensive review of the Fukushima accident to develop
lessons learned for new reactor designs and the subsequent
development and implementation of new regulatory
safeguards to protect public health and safety.” Id. at 172. The
Commission denied the request for immediate postponement
as premature, but directed NRC staff to consider the
submissions as comments to the AP1000 rulemaking. Id. at
172-73. Petitioners filed additional supplemental comments
requesting that NRC consider the environmental implications
of the Fukushima accident and the Task Force Report.
Supplemental Comments by the AP1000 Oversight Group et
al. Regarding Failure of Rulemaking on Certification, In the
Matter of AP1000 Design Certification Amendment, NRC-
2010-0131 (Sept. 29, 2011), reprinted in J.A. 326-36.
     In August 2011, after the Task Force issued its report,
several Petitioners submitted motions to reopen the record of
the then-closed Vogtle licensing proceeding and admit
contentions challenging the failure of NRC to order a
supplemental Vogtle EIS to address the environmental
implications of the Task Force Report. See PPL Bell Bend,
L.L.C., LBP-11-27, slip op. (Oct. 18, 2011). Two groups of
Petitioners submitted substantively identical proposed
contentions, which read as follows:
                              14
    The EIS for . . . Vogtle fails to satisfy the requirements of
    NEPA because it does not address the new and significant
    environmental     implications    of    the    findings   and
    recommendations raised by NRC’s Fukushima Task Force
    Report, including seismic-flood and environmental justice
    issues. As required by 10 C.F.R. § 51.92(a)(2) and 40 C.F.R.
    § 1502.9(c), these implications must be addressed in a
    supplemental Draft EIS.
Id. at 6. The contention was supported by declarations which
alleged that the Fukushima accident and the Task Force
Report presented new and significant information about risks
to public health and safety. See id. at 9-10 (summarizing
supporting declarations).
     On September 9, 2011, the Commission denied
Petitioners’ April 2011 Emergency Petitions with respect to
the Vogtle licensing decision and the AP1000 rule. The
Commission concluded that “nothing learned to date requires
immediate cessation of our review of license applications or
proposed reactor designs.” Union Elec., CLI-11-05, 74 N.R.C.
at 161. In addition, the Commission found that there was no
cause to require a “generic” environmental review because the
Fukushima accident did not present “new and significant”
information. Id. at 166-67. The Commission further noted that
“we do not know today the full implications of the Japan
events for U.S. facilities. Therefore, any generic NEPA duty –
if one were appropriate at all – does not accrue now.” Id. at
167.
     The Commission did, however, leave open the possibility
that an individual NEPA contention in a particular licensing
proceeding might require additional review, stating that “[i]f
the NRC determines that changes to its current environmental
assessment rules are warranted, we can revisit whether an
individual licensing review or adjudication should be held in
                               15
abeyance pending the outcome of a relevant rulemaking.” Id.
at 174.
     On October 18, 2011, the Board rejected as premature
Petitioners’ August 2011 contentions, “seeking to revive”
several closed adjudicatory proceedings, including the Vogtle
licensing. See PPL Bell Bend, LBP-11-27, slip op. at 1. The
Board read the Commission’s decision in CLI-11-05 as
instructing “precisely and definitively that it remains much
too early in the process of assessing the Fukushima event in
the context of the operation of reactors in the United States to
allow any informed conclusion regarding the possible safety
or environmental implications of that event.” Id. at 13. The
Board also noted that Petitioners did not indicate “any unique
characteristics of the [Vogtle] site that might make the content
of the Task Force report of greater environmental significance
to that reactor than to United States reactors in general.” Id. at
13-14. Because CLI-11-05 invited contentions in licensing
proceedings that alleged particular risks from the specific site,
the Board found this lack of specificity dispositive.
     Also on October 18, 2011, the Commission adopted all of
the Task Force recommendations and ordered NRC staff to
implement them within the following five years. See
Luminant Generation Co., LLC, LBP-11-36, slip op. at 4-5
(Nov. 30, 2011). Upon the Commission’s adoption of the
Task Force recommendations, several Petitioners resubmitted
their contentions and asked the Board to reconsider its denial
of their contentions in light of the Commission’s decision to
adopt all of the Task Force recommendations. See id.
    On November 30, 2011, the Board denied the motion to
reconsider, finding that the Commission’s adoption of the
Task Force recommendations had not “materially changed
matters.” Id. at 5. The Board noted that there had been no
express request that it reconsider the framework underlying its
                              16
prematurity decision in LBP-11-27, and it declined to do so.
Id. at 3-4.
     On February 9, 2012, the Commission handed down its
opinion resulting from its September 27 and 28, 2011,
mandatory hearing on the Vogtle licensing application. See S.
Nuclear Operating Co., CLI-12-02, slip op. at 2 (Feb. 9,
2012). Under Commission precedent, participation in the
hearing was appropriately limited to Southern and NRC staff,
and the hearing addressed only the sufficiency of the staff’s
review of Southern’s license application. See Exelon
Generation, 62 N.R.C. at 49-50. At the hearing, NRC
technical staff confirmed that the AP1000 design certification
and the Vogtle licenses met current safety and environmental
standards. S. Nuclear Operating Co., CLI-12-02, slip op. at
22. NRC staff testified that Fukushima-like accidents have an
“extremely low probability,” despite their “potentially high
consequences.” Id. at 74. The Commission considered the
likelihood and consequences of potential severe accidents
similar to the Fukushima accident and found that the risks to
the AP1000 reactor design at the Vogtle site were “lower than
those for current generation plants.” Id. at 72-73.
     NRC approved the combined license applications for the
Vogtle 3 and 4 reactors at the conclusion of the mandatory
hearing. The Commission found that the staff’s review
adequately supported the requisite safety and environmental
findings under 10 C.F.R. §§ 52.97, 51.107(a) & (d), and
50.10, that all NEPA requirements had been met, and that the
staff had followed an appropriate process for assessing “new
and significant” information. See id. at 2, 79. In addition, the
Commission restated that no plant, including Vogtle, would
be exempt from Task Force recommendations enacted in the
future:
    All affected nuclear plants will be required to comply with
    NRC direction resulting from lessons learned from the
                              17
    Fukushima accident, regardless of the timing of issuance of
    the affected licenses. We therefore expect the new Vogtle
    units will comply with all applicable “post-Fukushima”
    requirements.
Id. at 82. NRC found it premature to order implementation of
the Task Force recommendations, as many recommendations
were still in development and not yet formulated into
regulations. Instead, the Commission stated that it would not
establish new regulatory processes or requirements until after
taking sufficient time to “ensure that any new requirements
are technically justified and implemented appropriately.” Id.
     Commission Chairman Jaczko dissented from the
Commission’s decision, stating that he would not “authorize
issuance of these licenses without any binding obligation that
these plants will have implemented the lessons learned from
the Fukushima accident before they operate.” Id. (Jaczko, C.,
dissenting) slip op. at 1. Even Chairman Jaczko, however, did
not argue that a supplemental EIS was necessary before the
Vogtle licenses could proceed; his dissent was based solely on
his belief that the Commission should have demanded
assurances of compliance with future safety requirements, not
current environmental shortcomings.
     On March 16, 2012, the Commission upheld the Board’s
denial of Petitioners’ contention, agreeing that Petitioners had
“not identified environmental effects from the Fukushima
Dai-ichi events that can be concretely evaluated at this time,
or identified specific new information challenging the site-
specific environmental assessments” for Vogtle. Luminant
Generation Co., CLI-12-07, slip op. at 9. The Commission
held that the Task Force’s recommendations did not
themselves identify any environmentally significant
information for Vogtle, and Petitioners did not explain how
any particular recommendation related to the Vogtle licenses
in a manner that mandated a supplemental EIS. NRC held that
                               18
the Task Force recommendations, standing alone, did not
provide sufficient support for an admissible contention.
Rather, the Commission held that a valid contention must
“include facts sufficient to demonstrate a genuine dispute”
with the license application; a contention that merely alludes
to Task Force findings “is too vague . . . for litigation.” Id. at
13-14.
     The Commission also found that Petitioners failed to
demonstrate that the Task Force Report presented a “seriously
different picture of the environmental impact of the proposed
project from what was previously envisioned” that would
necessitate a supplemental EIS. Id. at 10. NRC held that
“reference to the Task Force Report recommendations alone,
without facts or expert opinion that explain their significance
for the unique characteristics” of the Vogtle reactors “does
not provide sufficient support” to demand further NEPA
review. Id. at 13. NRC ruled that the same lack of specificity
was also fatal to Petitioners’ attempt to meet NRC’s “more
stringent reopening rule” and to require Southern to
supplement the Vogtle EIS. Id. at 14 n.47.
     On April 16, 2012, the Commission denied Petitioners’
motion to stay the effectiveness of the Vogtle licensing
decision, pending review by this court. The Commission
reiterated its conclusion that Petitioners “have not
demonstrated that the Fukushima events or any regulatory
response to those events would raise environmental impacts
that differ significantly from the impacts that the NRC has
already reviewed and addressed” in approving the Vogtle
licenses. See S. Nuclear Operating Co., CLI-12-11, slip op. at
12-13 (Apr. 16, 2012).
    On February 17, 2012, Petitioners sought review of the
NRC’s AP1000 rule. A month later, Petitioners sought review
of the Commission’s decisions rejecting Petitioners’
contentions and of all the authorizations resulting from the
                              19
approval of the Vogtle licenses. On April 3, 2012, we
consolidated the petitions for review. After the Commission
denied Petitioners’ motion for a stay, Petitioners moved for a
stay in this court, which we denied.
     On appeal before us now are (1) the amended AP1000
design certification rule, (2) the Commission’s rejection of
Petitioners’ contentions and motions to reopen the record to
supplement the Vogtle EIS, and (3) all the licensing
authorizations resulting from the Commission’s decision to
allow the Vogtle licenses to go forward. The specific
decisions implicated are:
   The AP1000 rule, Final Rule, AP1000 Design Certification
    Amendment, 76 Fed. Reg. 82,079 (Dec. 30, 2011); and
   The Commission’s rejection of Petitioners’ contentions and
    motions to reopen the record, and the resulting licenses and
    work authorizations:
       o   Luminant Generation Co., LLC, CLI-12-07, slip op.
           (Mar. 16, 2012);
       o   Luminant Generation Co., LLC, LBP-11-36, slip op.
           (Nov. 30, 2011);
       o   Vogtle Electric Generating Plant, Units 3 and 4;
           Issuance of Combined Licenses and Limited Work
           Authorizations and Record of Decision, 77 Fed. Reg.
           12,332-02 (Feb. 29, 2012);
       o   Combined License No. NPF-91 (Vogtle Electric
           Generating Plant Unit 3) (Feb. 10, 2012), reprinted in
           J.A. 35;
       o   Combined License No. NPF-92 (Vogtle Electric
           Generating Plant Unit 4) (Feb. 10, 2012), reprinted in
           J.A. 53;
                             20
       o   Limited Work Authorization No. LWA-001, (Vogtle
           Electric Generating Plant Unit 3) (Feb. 10, 2012),
           reprinted in J.A. 71; and
       o   Limited Work Authorization No. LWA-002, (Vogtle
           Electric Generating Plant Unit 4) (Feb. 10, 2012),
           reprinted in J.A. 83.


              III. STANDARD OF REVIEW
     This court will set aside an agency rule or licensing
decision only if it is “arbitrary, capricious, an abuse of
discretion, or otherwise not in accordance with law.” 5 U.S.C.
§ 706(2)(A); see also, e.g., Advocates for Highway & Auto
Safety v. Fed. Motor Carrier Safety Admin., 429 F.3d 1136,
1144 (D.C. Cir. 2005).
     The arbitrary and capricious standard also controls our
review of agency actions with respect to any substantive
environmental issues that are properly before the court. We
may set aside such actions only if we find that NRC
committed “a clear error of judgment.” Marsh, 490 U.S. at
385. We owe deference to NRC’s decision not to supplement
either its EA for the AP1000 reactor design or its EIS for the
Vogtle reactors. See id. (finding that the agency “conducted a
reasoned evaluation of the relevant information and reached a
decision that, although perhaps disputable, was not ‘arbitrary
or capricious’”); see also Great Old Broads for Wilderness v.
Kimbell, 709 F.3d 836, 853-55 (9th Cir. 2013) (reviewing
decision not to supplement an EIS under the deferential
“arbitrary or capricious” standard).
    To the extent that NRC’s technical judgments and
predictions are before the court for review, we “must
generally be at [our] most deferential.” Balt. Gas & Elec. Co.
v. Natural Res. Def. Council, Inc., 462 U.S. 87, 103 (1983).
We are obligated to “defer to the wisdom of the agency,
                               21
provided its decision is reasoned and rational.” Dillmon v.
Nat’l Transp. Safety Bd., 588 F.3d 1085, 1089 (D.C. Cir.
2009).
     In reviewing NRC’s interpretations of its own rules –
here, notably, its rules governing the reopening of closed
proceedings and governing contention admissibility – we give
“controlling weight” to the agency’s constructions unless they
are “plainly erroneous or inconsistent with the regulation.”
City of Idaho Falls, Idaho v. FERC, 629 F.3d 222, 228 (D.C.
Cir. 2011).
     NRC’s interpretation of its enabling legislation is
reviewed pursuant to the familiar standards enunciated in
Chevron, U.S.A., Inc. v. Natural Resources Defense Council,
Inc., 467 U.S. 837, 842-45 (1984). See also, e.g., Nuclear
Info. Res. Serv., 969 F.2d at 1173. An agency’s interpretation
of its governing statute is entitled to no judicial deference if
“Congress has directly spoken to the precise question at
issue.” Chevron, 467 U.S. at 842. If, as in this case, “Congress
has explicitly left a gap for the agency to fill, there is an
express delegation of authority to the agency to elucidate a
specific provision of the statute by regulation. Such legislative
regulations are given controlling weight unless they are
arbitrary, capricious, or manifestly contrary to the statute.” Id.
at 843-44. We have previously endorsed NRC’s “high
standards” for reopening closed hearings and the “stringency
of those criteria.” Deukmejian, 751 F.2d at 1316. We are
therefore bound to defer to NRC’s implementation of its
contention-specificity regulations.
    We are also “obliged to defer to the operating procedures
employed by an agency when the governing statute requires
only that a ‘hearing’ be held.” Union of Concerned Scientists,
920 F.2d at 54. As a result, we consider with due deference
NRC’s rejection of Petitioners’ objections to the agency
procedures at issue here.
                               22
                       IV. ANALYSIS
A. NRC’s Refusal to Admit Petitioners’ Contentions
     NRC regulations dictate the criteria that a party’s
contention must meet in order to initiate a contested hearing.
See 10 C.F.R. § 2.309(f)(1). Because we have held that
NRC’s “procedural rules [under 10 C.F.R. § 2.309(f)] do not
facially violate the Atomic Energy Act or the APA [and] they
are also consistent with NEPA,” Union of Concerned
Scientists, 920 F.2d at 56-57, and because we find that NRC
reasonably applied these rules in evaluating Petitioners’
contentions, we defer to NRC’s rejection of Petitioners’
contentions.
      After carefully reviewing the record in this case, we hold
that the Commission acted reasonably in denying Petitioners’
contentions on the grounds that they (1) failed to “[p]rovide
a . . . statement of the alleged facts or expert opinions which
support the requestor’s/petitioner’s position,” 10 C.F.R.
§ 2.309(f)(1)(v), and (2) failed to “include references to
specific portions of the . . . environmental report . . . that the
petitioner disputes and the supporting reasons,” id.
§ 2.309(f)(1)(vi). See Luminant Generation Co., CLI-12-07,
slip op. at 13 n.43.
    1. The Task Force Report Alone Was Not a “New and
       Significant” Circumstance Requiring a Supplemental
       EIS
     Petitioners failed to indicate any environmental data that
were not considered in the EIS. Because Petitioners failed to
point to any specific shortcoming in the EIS, NRC reasonably
found Petitioners’ contentions insufficient to support a
contested hearing. The Commission clearly stated its reasons
for refusing to admit Petitioners’ contentions:
                               23
    We expect Petitioners to identify information that was not
    considered in the environmental review for the application at
    issue and explain, with asserted facts or expert opinion, how it
    presents “a seriously different picture of the environmental
    impact of the proposed project from what was previously
    envisioned.”
Id. at 13. This explanation is well-supported by the record and
represents a reasonable interpretation of NRC’s contention-
specificity regulations. See 10 C.F.R. § 2.309(f).
     Under NEPA, NRC is obligated to undertake a
supplemental EIS only when presented with “substantial
changes in the proposed action that are relevant to
environmental concerns” or “new and significant
circumstances or information relevant to environmental
concerns and bearing on the proposed action or its impacts”
after the EIS is assembled. 10 C.F.R. § 51.92(a)(1)-(2); see
also id. § 51.72(a)(1)-(2). “New and significant” information
presents “a seriously different picture of the environmental
impact of the proposed project from what was previously
envisioned.” Hydro Res., Inc., 50 N.R.C. 3, 14 (1999); see
also Marsh, 490 U.S. at 374 (looking to “the value of the new
information to the still pending decisionmaking process” and
requiring a supplemental EIS only if the new information is
sufficient to show environmental effects “in a significant
manner or to a significant extent not already considered”).
The determination as to whether information is either new or
significant “requires a high level of technical expertise”; thus,
we “defer to the informed discretion of the [Commission].”
Marsh, 490 U.S. at 377.
     Petitioners contend that the Task Force recommendations
give rise to an obligation to supplement the Vogtle EIS
because the recommendations may alter NRC regulations in
the years ahead. Thus, in Petitioners’ view, the Vogtle
licenses necessarily must be delayed until the
                                24
recommendations are finalized. We rejected a similar line of
reasoning in Union of Concerned Scientists:
    Information raised in the environmental reports does not
    amount to a new material “issue” simply because it adds
    marginal weight to the case of an opponent or a proponent of a
    license; the reports instead raise a new “issue” only when the
    argument itself (as distinct from its chances of success) was
    not apparent at the time of the application. Although the
    concepts of new issues and new evidence are analytically
    distinct, we recognize that in practice they can converge – the
    demarcation line may depend on how the “issue” is stated.
    Still, whether an actual new “issue” is raised is a matter for the
    NRC to determine in the first instance and is reviewed
    deferentially.
920 F.2d at 55.
    It is also noteworthy that the position taken by the
Commission in this case is consistent with holdings reached
by Atomic Safety and Licensing Boards in licensing
proceedings for other locations. In these proceedings, the
Boards have found that the Task Force Report alone does not
provide a sufficient foundation for an admissible contention.
See Pac. Gas & Elec. Co., LBP-11-32, slip op. at 19 (Nov. 18,
2011) (finding a proposed contention inadmissible because
the petitioner “offer[ed] nothing to link the outcome of the
Fukushima events” to the pending license renewal
application), review denied at Pac. Gas & Elec. Co., CLI-12-
13 (Jun. 7, 2012); Fla. Power & Light Co., LBP-11-33, slip
op. at 8 (Nov. 21, 2011) (rejecting proposed contention
because the petitioners “allege[d] no facts linking the events
at Fukushima to the sufficiency of NEPA-related documents”
for the pending combined license application). Obviously,
these Board decisions do not control the disposition of this
case, but they do give further credence to the view that the
Task Force Report alone does not support Petitioners’
position.
                                25
     In this case, NRC’s original EIS for Vogtle considered
precisely the types of harm that occurred as a result of the
Fukushima accident. The EIS considered consequences and
mitigation of severe accidents involving reactor core damage
and the release of fission products. See Vogtle EIS at § 5.10,
reprinted in J.A. 805-09; see also Final Environmental Impact
Statement for an Early Site Permit (ESP) at the Vogtle
Electric Generating Plant Site, § 5.10.2 (Aug. 2008) (“Vogtle
ESP EIS”), reprinted in J.A. 835-44. In addition, the EIS for
the Vogtle early site permit evaluated the human health
impacts, economic costs, and land contamination risks,
concluding that the environmental risks associated with
severe accidents from an AP1000 reactor at the Vogtle site
“would be small compared to risks associated with operation
of the current-generation reactors at [Vogtle]” and were “well
below NRC safety goals.” Vogtle ESP EIS at 5-81, 5-89,
reprinted in J.A. 836, 844.
     Petitioners’ contentions provide no explanation as to how
the Task Force Report recommendations raise previously
unaddressed issues. See Union of Concerned Scientists, 920
F.2d at 55. The Commission reasonably concluded that, for
their contentions to be admitted for consideration, Petitioners
were required to cite particular information that was missing
from the Vogtle EIS based on particular recommendations
from the Task Force. See Luminant Generation Co., CLI-12-
07, slip op. at 13; PPL Bell Bend, LBP-11-27, slip op. at 13.
Petitioners failed to do this.
     Petitioners argue that, once NRC described the
Fukushima accident as “significant,” the agency was
obligated to generate new environmental reports for all
implicated pending sites and reactor designs. This argument is
clearly unavailing, as it relies on Petitioners’ elision of “safety
significance” with “environmental significance.” In the case
on which Petitioners chiefly rely, San Luis Obispo Mothers
                             26
for Peace v. NRC, 449 F.3d 1016 (9th Cir. 2006), NRC had
categorically declined to consider any environmental
consequences resulting from terrorism-related threats. The
Ninth Circuit thus overturned the Commission’s decision. Id.
at 1031. The situation here is quite different. In this case,
NRC thoroughly analyzed the environmental consequences of
severe accidents for Vogtle. See Vogtle ESP EIS at § 5.10.2,
reprinted in J.A. 835-44; Vogtle EIS at § 5.10, reprinted in
J.A. 805-09. Chairman Jaczko, the lone dissenter from the
issuance of the Vogtle licenses, objected because he sought
greater assurances that the Vogtle reactors would remain in
compliance with future safety regulations. The Chairman did
not contend that his concerns about safety standards created
present environmental concerns; and he did not claim that
there were any present shortcomings at the Vogtle site or any
need for additional NEPA review. See generally S. Nuclear
Operating Co., CLI-12-02, slip op. (Jaczko, C., dissenting).
     “[N]ew information about nuclear power plant safety
arising between the time of the initial application and the
commencement of operations” does not necessarily provide
cause for additional NEPA review. Union of Concerned
Scientists, 920 F.2d at 55. And it does not create such cause
here because the EIS addressed and dismissed precisely the
risks that gave rise to the Fukushima accident. The
Commission reasonably found that it was not obligated to
postpone its decision “until inchoate information matures into
something that might later affect [its] review.” Luminant
Generation Co., CLI-12-07, slip op. at 14; see also N.J. Dep’t
of Envtl. Prot. v. NRC, 561 F.3d 132, 143 (3d Cir. 2009)
(holding that “precautionary actions to guard against a
particular risk do not trigger a duty to perform a NEPA
analysis”).
   Furthermore, as noted above, both the Task Force and
NRC noted that further regulatory initiatives would be
                              27
possible, as necessary, after the Commission studied the Task
Force recommendations. See S. Nuclear Operating Co., CLI-
12-02, slip op. at 81-82. However, merely because the
Commission might impose more stringent safety regulations
after carefully assessing the Task Force recommendations
does not mean that the agency’s present actions are
inconsistent with NEPA.
     Without an explanation from Petitioners as to what
specific “new and significant” environmental information
NRC failed to consider, or what deficiency in the existing EIS
it failed to rectify, NRC reasonably found that Petitioners’
contentions did not warrant a contested hearing. Petitioners’
attempts to rely on future safety concerns in lieu of present
environmental risks do not create an obligation for further
NEPA review.
    2. Petitioners’ Contentions Lacked Specific Links
       Between the Fukushima Accident and the Vogtle Site
     After the Task Force issued its report, the Commission
rejected as premature Petitioners’ requests for a generic
NEPA review arising out of the Task Force Report. The
Commission held that if “new and significant information
comes to light that requires consideration as part of the
ongoing preparation of application-specific NEPA documents,
the agency will assess the significance of that information, as
appropriate.” Union Elec., CLI-11-05, 74 N.R.C. at 167.
Petitioners do not challenge this decision on appeal, but
instead “attempt to distinguish CLI-11-[0]5 by claiming that
[the Commission’s] holding there rested on a finding that
sufficient information was not yet available to conduct a
generic analysis,” and that such information now exists.
Luminant Generation Co., CLI-12-07, slip op. at 9. The
Commission rejected this argument and upheld the Board’s
ruling “that Petitioners did not relate their contention to any
unique characteristics of the particular site at issue, and
                              28
therefore, the contention was akin to the generic type of
NEPA review that we declared premature in CLI-11-[0]5.” Id.
(citing PPL Bell Bend, LBP-11-27, slip op. at 13-14).
     The First Circuit, addressing an appeal from NRC’s
denial of other post-Fukushima objections to plant licensing
actions, held that a petitioner’s “mere pointing to a piece of
information and speculating that the results of the
[environmental risk analysis] may be different was not
sufficient to meet” the Commission’s stringent standards for
reopening a closed proceeding. Massachusetts v. NRC, 708
F.3d 63, 76-77 (1st Cir. 2013). We agree. We therefore
uphold NRC’s determination that its rejection of Petitioners’
contentions as “premature” was governed by its decision in
CLI-11-05.
     In light of the Commission’s decision in CLI-11-05,
Petitioners were obligated to present a contention sufficiently
detailed and specifically related to the challenged reactor
location to demonstrate how the contention differed from the
“premature” generic request that the Commission denied in
CLI-11-05. Absent any evidence – or even allegation –
linking the conditions at the Vogtle site itself to the Task
Force recommendations, NRC appropriately applied the
applicable contention-specificity regulations in declining to
admit Petitioners’ contentions. We defer to the Commission’s
judgment. See Idaho Falls, 629 F.3d at 228.
B. Declining to Allow Petitioners to Intervene in
   Mandatory Hearing
     Petitioners challenge their exclusion from NRC’s
mandatory hearing regarding the Vogtle licenses. Their claim
is meritless. As discussed above, there was no need for an
additional contested hearing once NRC reasonably denied
Petitioners’ contentions. Petitioners participated in two
                             29
contested hearings related to the Vogtle licenses. They had no
right to participate in the Commission’s “mandatory” hearing.
     Mandatory hearings are “sufficiency” reviews, designed
to assess the efforts of the NRC staff and determine whether
the safety and environmental record is sufficient to support
the license. Participation in these hearings is limited to the
license applicant and NRC staff. Exelon Generation, 62
N.R.C. at 49-50 (2005) (petitioners are “barred from
participating in the uncontested portion of the hearing”).
Petitioners point to no statutory or regulatory provision, nor
agency practice, affording them a right to participate in a
mandatory hearing. We therefore reject their claim on this
point.
C. Approval of AP1000 Reactor Design Certification
     Finally, we hold that NRC properly declined to
supplement its existing EA for the AP1000 design
certification amendment before adopting the final rule. The
EA for a design certification amendment considers only
whether the design change that is the subject of the proposed
amendment renders a previously rejected Severe Accident
Mitigation Design Alternative cost beneficial or identifies a
new alternative necessitating its own cost-benefit analysis.
See 10 C.F.R. § 51.30(d). The Commission reasonably found
that the existing AP1000 EA adequately considered Severe
Accident Mitigation Design Alternatives.
    In considering the AP1000 design certification
amendment, NRC reexamined the probability that a severe
accident might occur and concluded that potential design
changes did not affect its original evaluations. Environmental
Assessment by NRC Relating to the Certification of the
Amendment to the AP1000 Standard Plant Design, Docket
No. 52-006 at 5, (Dec. 22, 2011), reprinted in J.A. 224; see
also AP1000 Design Certification Amendment, 76 Fed. Reg.
                              30
at 82,096; NRC Responses to Public Comments, Final Rule:
Amendment to AP1000 Design Certification Rule at 15-23
(Dec. 2011), reprinted in J.A. 268-76 (detailing public
comments and explaining why no supplemental EA was
necessary); id. at 44-45, reprinted in J.A. 280-81 (detailing
the reasons no additional Severe Accident Design Mitigation
Alternatives were necessary). NRC erred “on the side of high
consequences” and concluded that the AP1000 EA “make[s] a
convincing case that no identified [Severe Accident
Mitigation Design Alternative] is worth the expense.” NRC
Responses to Public Comments at 45, reprinted in J.A. 281.
Petitioners do not challenge this analysis, nor do they connect
any of the Task Force recommendations to any alternative
that NRC failed to consider. Without an explicit challenge,
NRC appropriately relied on its 2011 EA in approving the
final AP1000 rule amendment. Indeed, the Task Force Report
“supports completing [the AP1000] design certification
rulemaking activities without delay.” Task Force Report at
71-72; see also AP1000 Design Certification Amendment, 76
Fed. Reg. at 82,083.
     Petitioners have failed to demonstrate that NRC acted
less than reasonably in declining to order a supplemental EA
for the AP1000 design certification amendment. We therefore
defer to the Commission’s conclusion that such a supplement
was unnecessary.


                     V. CONCLUSION

    For the foregoing reasons, the petition for review is
denied.
