Opinion for the Court filed by Circuit Judge SENTELLE.
Dissenting opinion on the denial of a pre-operational hearing on new safety information filed by Circuit Judge WALD, with whom Chief Judge MIKVA and Circuit Judge HARRY T. EDWARDS join.
Opinion concurring in part and dissenting in part filed by Circuit Judge BUCKLEY.
SENTELLE, Circuit Judge:
We today review en banc a Nuclear Reg-. ulatory Commission (“NRC” or “Commission”) rule aimed at substantially revamping the licensing process for nuclear power plants. 10 C.F.R. Part 52. This matter was previously heard by a panel of this Court in Nuclear Information and Resource Service v. United States NRC, 918 F.2d 189 (D.C.Cir.1990) (“NIRS”).
The panel concluded that the Commission’s decision in Part 52 to. authorize issuance of a single, “combined license” in lieu of separate construction and operating permits was acceptable under the Atomic Energy Act (“Act” or “AEA”). It likewise upheld the Commission’s reliance on a pre-approval process for assessing reactor designs and sites. The panel did, however, declare facially invalid Part 52’s regulations regarding the Commission’s duties in making findings and holding hearings after construction is completed and before operation begins.
After rehearing, we continue to affirm the Commission’s combined license procedures and its reliance on the pre-approval process; however, we now also hold that the post-construction procedures embodied in Part 52 are based on a permissible reading of the AEA.
I.
Before conducting the rulemaking now before us, the NRC licensed nuclear reactors in two regulatory steps. See 10 C.F.R. Part 50. At the first step, the Commission was required to find the proposed site and preliminary design plans acceptable, and conduct a public hearing on these matters; thereafter, the Commission issued a construction permit. Upon completion of construction, the licensee then sought an operating license, which could be granted only after the Commission approved the reactor’s final design, made several other findings, and conducted another public hearing.
Because Part 50 allowed the NRC to issue a construction permit on incomplete design information, it often became necessary for the Commission to impose new regulatory requirements as construction continued and plans changed. A “design-as-you-go” approach on the part of licensees was mirrored by a “regulate-as-you-go” tack on the part of the Commission. The result of this regimen was, as the Office of Technology Assessment has stated, that
[essentially every reactor ... has been custom-designed and custom-built. The fact that almost every reactor is “one of a kind” has led to excessive difficulty in verifying the safety of individual plants and identifying particular problems in transferring the safety lessons from one reactor to another.
Congress of the United States, Office of Technology Assessment, Nuclear Power Plant Standardization at 3 (1981).
After a number of unsuccessful attempts to persuade Congress to restructure the licensing process through new legislation, in 1987 the Commission moved to reform reactor licensing regulations under existing legislation. It did so with two announced objectives: to standardize nuclear power plant design, and to establish a procedural framework for resolving with some finality as many safety and environmental issues as possible before — rather than after — construction begins. See 52 Fed.Reg. 34,884 (1987). In 1989, the Commission announced its final product, known collectively as Part 52. 54 Fed.Reg. 15,372 (1989) (codified at 10 C.F.R. Part 52).
Pre-Approval of Designs and Sites. One major feature of Part 52 is the NRC’s new regulatory scheme for pre-approval of standardized power plant designs by rule-making. 10 C.F.R. Part 52, Subpart B. Under Subpart B, an applicant files with the Commission a proposed design; if, after a period of notice and comment and a possible hearing, the Commission concludes that the design is safe, it issues a design certification. 10 C.F.R. §§ 52.41-.63. This certification remains effective for 15 years, and is renewable in successive rulemak-ings. 10 C.F.R. §§ 52.57-61. Thus, the procedure allows applicants to register a “generic” design with the Commission that may be utilized any number of times during the life of the certification.
Related to the pre-approval process for plant designs is one for the early determination of plant sites. 10 C.F.R. Part 52, Subpart A. Under the “early site permit” process, the Commission may, after conducting a hearing and making necessary findings, approve a site permit. 10 C.F.R. §§ 52.11-.39. While a site permit does not authorize construction, it does establish design criteria for plant construction on the proposed site. Moreover, it retains validity for up to 20 years, though the NRC may extend this period after another examination. 10 C.F.R. §§ 52.29-.33.
Combined Licenses. Part 52 also establishes a process by which an applicant may obtain a “combined license.” 10 C.F.R. Part 52, Subpart C. A combined license constitutes not only a construction permit, but also a conditional operating permit. Issued before construction, it forms the centerpiece of the Commission’s effort to resolve as many issues as possible as early in the licensing process as possible. See 54 Fed.Reg. at 15,373-74 (1989).
The Commission requires an applicant for a combined license under Part 52 to provide a much higher level of detail concerning the final design of the facility than was needed for a construction permit under Part 50. Before issuing the new combined license, the Commission must find that the proposed final design complies with the Act and NRC regulations; it must also hold a hearing on all related issues. 10 C.F.R. §§ 52.79, 52.85, 52.97. If, however, a combined license application references a pre-approved design, issues regarding design will be deemed resolved; the Commission will conduct no new findings regarding the design and the required hearing will not encompass issues heard at the design certification stage. Id.
Even if referencing a pre-approved design, the applicant must still show at this stage that the certified design can be successfully linked to site-specific design elements. Id. The Commission is obliged to hold hearings and make findings on this linkage. Id. If, however, the combined license application references not only a pre-approved design, but also a pre-ap-proved site, the applicant need only demonstrate at this stage that the design falls within the parameters specified in the early site permit. Consequently, the Commission’s duty to hold hearings and conduct findings will be limited to this issue. Id.
In addition to the foregoing, the Commission must also set forth the “acceptance criteria” for the proposed plant at this juncture. 10 C.F.R. § 52.97(b). Acceptance criteria are the tests, inspections, and analyses the Commission will conduct after construction is completed to ensure that the facility has been built and will operate in conformance with the license and the Act. Id. The content of the acceptance criteria is subject to litigation in the combined license hearing. If any changes are required after the combined license is issued, the Commission must hold more hearings and make further findings before issuing a license amendment; all license amendments must be approved before operation may commence. Id.
Post-Construction Procedures. After construction is complete, the Commission— having approved the design and site, and having approved the match between the design and site — treats every licensing issue as finally resolved, save whether the plant as actually built meets the specifications established by the acceptance criteria. Consequently, under § 52.103(b)(1)(i) the Commission will entertain only petitions showing “prima facie, that one or more of the acceptance criteria in the combined license have not been met and, as a result, there is good cause to modify or prohibit operation.” If a prima facie case is made out, and certain other requirements met, a formal hearing on conformance to the acceptance criteria will be held. See §§ 52.-103(b)(1)(i) and (2)(i). At the end of this hearing, the Commission must, under § 52.-103(c), find that “the acceptance criteria ... have been met and ... accordingly, the facility has been constructed and will operate in conformity with the Atomic Energy Act.” (Emphasis added.)
In sum, Part 52’s post-construction procedures limit the NEC’s role to determining whether the plant was constructed as its license required; it is not to revisit issues settled at prior stages in the regulatory process, but to rely on the hearings held and findings made at those stages. In this regard, the post-construction procedures parallel the combined license procedures where, again, the Commission treats issues addressed at the pre-approval step as finally resolved.
Nonetheless, the Commission does make available after construction a mechanism for the rehearing and reconsideration of the terms and conditions of the combined license itself. See 10 C.F.R. §§ 52.-103(b)(1)(h) and (2)(ii). Anyone may file a petition with the Commission discussing any issue affecting a license’s continuing validity. The Commission is obliged to consider whether any immediate action is required and respond to any petition it denies with a written statement of reasons. Id.
II.
A.
Petitioners object to the combined license and the early approval procedures in Subparts A and B. They assert that these new regulations run afoul of the plain language of § 185 of the AEA which evidences Congress’s intent to mandate statutorily the traditional two-step licensing process. The panel rejected this reading of § 185, holding instead each of these innovations acceptable under the Act. NIRS, 918 F.2d at 192-93 & n. 14. After rehearing, we continue to adhere to this conclusion and, consequently, have no reason to revisit petitioners’ arguments on this score.
B.
Petitioners next object to the Commission’s proposed post-construction procedures. Specifically, they complain of the Commission’s reliance on pre-construction rulemakings and hearings to winnow down the issues to be heard and resolved after construction. They contend that the post-construction hearing opportunity must, as the Act is presently written, allow a full opportunity to revisit material design, siting, and other issues discussed at the preapproval or combined license stages. Therefore, § 52.103(b), allowing a formal hearing only on issues relating to compli-anee with the acceptance criteria, is facially invalid. Likewise, they argue that the Act requires the NRC to make fresh findings on any and all issues after construction is completed. Thus, § 52.103(c), permitting the Commission to find simply that the acceptance criteria are met and the AEA is “accordingly” satisfied, also trenches upon the Act’s dictates. The panel adopted petitioners’ position, see NIRS, 918 F.2d at 194-97, invalidating §§ 52.103(b) and (c).
We today reexamine these questions, applying the principles set forth in Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 842-44, 104 S.Ct. 2778, 2781-82, 81 L.Ed.2d 694 (1984) (“Chevron”). Under the Chevron analysis, judicial review of an agency’s interpretation of a statute under its administration is limited to a two-step inquiry. At the first step, we inquire into “whether Congress has directly spoken to the precise question at issue.” Id. at 842, 104 S.Ct. at 2781. If we can come to the “unmistakable conclusion that Congress had an intention on the precise question at issue,” State of Ohio v. United States Dep’t of Interior, 880 F.2d 432, 441 (D.C.Cir.1989), our inquiry ends there; this Court naturally “must give effect to the unambiguously expressed intent of Congress.” Chevron, 467 U.S. at 843, 104 S.Ct. at 2781-82.
However, if the statute before us is “silent or ambiguous with respect to the specific issue,” before us, we proceed to the second step. Id. At this stage, we “defer to the agency’s interpretation of the statute if it is reasonable and consistent with the statute’s purpose,” Chemical Manufacturers Ass’n v. EPA, 919 F.2d 158, 162-63 (D.C.Cir.1990); we are not free to “impose [our] own construction on the statute, as would be necessary in the absence of an administrative interpretation.” Chevron, 467 U.S. at 843, 104 S.Ct. at 2781-82 (footnote omitted). We now turn to review the NRC’s regulations under the Chevron rubric.
Chevron Step I. Section 189(a) of the Act contains the Commission’s statutory instructions concerning the need for, and conduct of, hearings in the licensing process. It provides in pertinent part that
[i]n any proceeding ... for the granting, suspending, revoking, or amending of any license or construction permit ... the Commission shall grant a hearing upon the request of any person whose interest may be affected by the proceeding- In cases where such a construction permit has been issued following the holding of a hearing, the Commission may, in the absence of a request therefor by any person ... issue an operating license.
42 U.S.C. § 2239(a)(1).
While this section plainly requires a “hearing upon request” before the “granting” of a license, it provides no unambiguous instruction as to how the “hearing” is to be held; nor does it speak in any direct fashion to the question of whether the Commission must rehear issues already resolved at earlier stages in the licensing process. As we noted in Union of Concerned Scientists v. NRC, 920 F.2d 50, 53-54 (D.C.Cir.1990) (“UCS II”):
[t]he [Atomic Energy] Act itself nowhere describes the content of a hearing or prescribes the manner in which this “hearing" is to be run. ... We are, of course, obliged to defer to the operating procedures employed by the agency [i.e. move to a Chevron step II analysis] when the governing statute requires only that a “hearing” be held. See, e.g., American Trucking Ass’ns v. United States, 627 F.2d 1313, 1319 n. 20, 1321 (D.C.Cir.1980) (noting that such “operating procedures” fall “uniquely within the expertise of the agency”); see also Richardson v. Wright, 405 U.S. 208, 209, 92 S.Ct. 788, 789-90, 31 L.Ed.2d 151 (1972); FCC v. Pottsville Broadcasting Co., 309 U.S. 134, 143-44, 60 S.Ct. 437, 441-42, 84 L.Ed. 656 (1940).
(Emphasis added.) In sum, the term “hearing” as it is used in § 189(a) gives this Court no plain textual authority to reject the Part 52 hearing scheme.
Petitioners themselves do not rest upon the express language of § 189(a) in protesting the validity of § 52.103(b). Rather, they turn to our prior precedent, pointing specifically to Union of Concerned Scientists v. NRC, 735 F.2d 1437 (D.C.Cir.1984) (“UCS I”), for the proposition that “[w]hen a statute requires a ‘hearing’ in an adjudicatory matter, such as licensing, the agency must generally provide an opportunity for submission and challenge of evidence as to any and all issues of material fact.” Id. at 1444. Reading the phrase “any and all issues of material fact” to require a post-construction hearing on any and all possible material issues, including those already heard at earlier points in the licensing scheme, petitioners reason § 52.103(b) to be invalid.
This reading of UCS I misconstrues the language and purpose of the case. UCS I did not require every hearing in the licensing process to encompass every material issue of fact. Rather, as UCS II made clear, UCS I “stands for the proposition that Section 189(a) prohibits the NRC from preventing all parties from ever raising in a hearing on a licensing decision a specific issue it agrees is material to that decision.” 920 F.2d at 54 (emphasis added). Taking this view of the UCS 7’s requirements, the Commission’s post-construction hearing regulations pose no problem. Under Part 52, parties are uncontestably permitted their day in court on every material issue at some point in the licensing process.
It is unlikely that we could validly read UCS I to require every material issue to be revisited at the post-construction hearing in light of Supreme Court decisions explicitly permitting agency reliance on prior rule-makings when a “hearing” is required. See generally discussion of Heckler v. Campbell, 461 U.S. 458, 103 S.Ct. 1952, 76 L.Ed.2d 66 (1983) and cases cited therein, infra pp. 1175-76. Such a reading would also appear to disregard the deference due an agency in the interpretation of its own organic statute by pouring content into the term “hearing” that is neither immediately apparent, see Heckler v. Campbell, nor advanced by the agency itself. See Chevron, 467 U.S. at 843, 104 S.Ct. at 2781-82. Further, by adding meaning to the term “hearing,” such a reading might also violate the Supreme Court’s admonition in Vermont Yankee Nuclear Power Corp. v. Natural Resources Defense Council, Inc., 435 U.S. 519, 98 S.Ct. 1197, 55 L.Ed.2d 460 (1978), against the judicial fashioning of administrative procedures that neither Congress nor the agency has sanctioned. Also, were we to construe UCS I so broadly, we would be obliged to invalidate not only the post-construction hearing opportunity, but also to question the combined license hearing procedures for they, too, allow the Commission to avoid matters settled at the pre-approval process.
Petitioners next turn to § 185 of the Act. This provision explains the findings the Commission must make before approving a reactor license. Petitioners contend that, whatever ambiguity exists in § 189(a) as to the Commission’s post-construction obligations, § 185 is crystal clear, leaving no doubt as to the Commission’s inability to rely on previous determinations to whittle down the issues to be heard and resolved after construction. According to § 185, however, the Commission need simply find that
the facility authorized has been constructed and will operate in conformity with the application as amended and in conformity with the provisions of this chapter and of the rules and regulations of the Commission.
42 U.S.C. § 2235.
In sum, the Act itself does require two post-construction findings — one regarding the plant’s accordance with the Act and one regarding its agreement with NRC regulations. But again there is nothing in the language of the statute indicating how the Commission is to go about satisfying these obligations.
Petitioners posit that because § 185 emphasizes that the Commission must demonstrate compliance with the Act itself — and not just NRC regulations — the Commission need conduct its hearings and make its findings anew after construction. The problem with this point: there is nothing in the statute to suggest that the Commission cannot rely on its prior decisions finding portions of the plant to be in compliance with the Act (e.g., its design after Subpart B proceedings, or its siting after Subpart A proceedings) when it makes its post-construction findings.
In fact, other sections of the Act suggest that the NRC is endowed with significant discretion in determining what information is necessary to support the various findings required in the licensing process. See, e.g., 42 U.S.C. § 2232(a) (“In connection with applications for licenses to operate ... utilization facilities [i.e. nuclear reactors], the applicant shall state such technical specifications ... and such other information as the Commission may ... deem necessary in order to enable it to find that the utilization ... will provide adequate protection to the health and safety of the public.”).
Significantly, the Supreme Court has found agency reliance on prior determinations to be perfectly acceptable, even when the statute before it plainly calls for individualized hearings and findings. See Heckler v. Campbell, 461 U.S. at 468-70, 103 S.Ct. at 1958-59 (though Social Security statute requires individualized hearings on whether individual claimant is entitled to disability benefits, agency may rely on a previously promulgated generic finding as to availability of jobs for people with specific disabilities); Baltimore Gas & Electric Co. v. Natural Resources Defense Council, Inc., 462 U.S. 87, 103 S.Ct. 2246, 76 L.Ed.2d 437 (1983) (statutory requirement for an environmental assessment does not preclude a scheme in which the NRC determines through rulemaking whether certain activities threaten the environment, and then limits individualized hearings to whether the facilities at issue involve those activities); United States v. Storer Broadcasting Co., 351 U.S. 192, 205, 76 S.Ct. 763, 771-72, 100 L.Ed. 1081 (1956) (upholding a Federal Communications Commission (“FCC”) rulemaking effectively eliminating many applicants from a station license competition, despite provision in the Federal Communications Act offering each applicant a “full hearing”); FPC v. Texaco, Inc., 377 U.S. 33, 41-44, 84 S.Ct. 1105, 1110-12, 12 L.Ed.2d 112 (1964) (mechanism providing for summary rejection of certain contracts between natural gas companies is consistent with Natural Gas Act’s “hearing” requirement). So too here. Though § 185 calls for a post-construction finding of compliance with the Act, it does nothing to intimate that the Commission may not rely on its previous findings that specific aspects of a plant satisfy the Act’s mandates.
Indeed, since the panel decision was handed down, the Supreme Court has reemphasized its endorsement of parallel practices in a pair of cases. In Mobil Oil Exploration & Producing Southeast, Inc. v. United Distribution Cos., 498 U.S. 211, 111 S.Ct. 615, 112 L.Ed.2d 636 (1991), the Court considered a provision of the Natural Gas Act mandating individualized proceedings before a company may abandon a gas supply or its contractual service obligations. In an 8-0 decision, the Court found the Federal Energy Regulatory Commission’s reliance on a promulgated, pre-authorized abandonment procedure in lieu of individualized hearings and findings in every case perfectly acceptable:
Time and again, “[t]he Court has recognized that even where an agency’s enabling statute expressly requires it to hold a hearing, the agency may rely on its rulemaking authority to determine issues that do not require case-by-case consideration.” ... “[A] contrary holding would require the agency continually to relitigate issues that may be established fairly and efficiently in a single rulemak-ing proceeding.”
Mobil Oil, 111 S.Ct. at 626 (quoting Heckler v. Campbell, 461 U.S. at 467, 103 S.Ct. at 1957).
In American Hosp. Ass’n v. NLRB, 111 5.Ct. 1539 (1991), the Court faced a provision of the National Labor Relations Act (“NLRA”) requiring the National Labor Relations Board (“NLRB”) to make a separate determination of the appropriate bargaining unit “in each case.” Petitioner suggested that the term “in each case” prevented the NLRB from delineating industry-wide rules regarding the applicable bargaining unit. The Supreme Court disagreed, unanimously concluding that
[a]s a noted scholar on administrative law has observed: “[T]he mandate to decide ‘in each case’ does not prevent the Board from ... [using] classifications, rules, principles, and precedents. Sensible men could not refuse to use such instruments and a sensible Congress would not expect them to.” ...
This reading of the “in each case” requirement comports with our past interpretations of similar provisions in other regulatory statutes. See United States v. Storer Broadcasting Co., 351 U.S. 192, 205, 76 S.Ct. 763, 771-72, 100 L.Ed. 1081 (1956); FPC v. Texaco, Inc., 377 U.S. 33, 41-44, 84 S.Ct. 1105, 1110-12, 12 L.Ed.2d 112 (1964); Heckler v. Campbell, 461 U.S. 458, 467, 103 S.Ct. 1952, 1957, 76 L.Ed.2d 66 (1983). These decisions confirm that, even if a statutory scheme requires individualized determinations, the decision-maker has the authority to rely on rulemaking to resolve certain issues of general applicability unless Congress clearly expresses an intent to withhold that authority.
American Hosp. Ass’n, 111 S.Ct. at 1543 (quoting K. Davis, Administrative Law Text 145 (3d ed. 1972)).
In sum, the Court has had occasion to face several substantive statutes, each of which apparently commands the relevant agency to hold individualized hearings and make fresh findings in every case, much as petitioners argue the statute before us requires the Commission to start its hearings and findings anew after construction. However, the Court has consistently held that reliance on prior determinations is perfectly harmonious with statutory schemes similar to the one now before us.
If reliance on prior determinations is acceptable in other statutory contexts requiring individualized hearings and findings, we must be particularly wary of suggestions that it is untenable on Chevron step I grounds under § 185. The AEA has been consistently read — as it was written — to give the Commission broad regulatory latitude. See Siegel v. Atomic Energy Comm’n, 400 F.2d 778, 783 (D.C.Cir.1968) (The Act “is virtually unique in the degree to which broad responsibility is reposed in the [Commission], free of close prescription in its charter as to how it shall proceed in achieving the statutory objectives.”). See also BPI v. Atomic Energy Comm’n, 502 F.2d 424, 428 n. 3 (D.C.Cir.1974); City of Statesville, et al. v. Atomic Energy Comm’n, 441 F.2d 962, 977 (D.C.Cir.1969). The Supreme Court, moreover, has forcefully instructed that this latitude is especially applicable when the NRC is structuring its “own rules of procedure and ... methods of inquiry.” Vermont Yankee, 435 U.S. at 543, 98 S.Ct. at 1211.
Finally, we note that, were the post-construction procedures invalid because of their dependence on prior determinations, the logic of petitioners’ interpretation of § 185 might undercut not only the post-construction procedures, but also the combined license. It, too, is tailored to avoid the reconsideration of issues settled in pri- or hearings. Thus, like a broad reading of UCS I, this would carry us much further than we went in the panel decision. See NIRS, 918 F.2d at 192-93, 196 n. 14.
Unable to conclude that the Act unambiguously prevents the NRC from adopting Part 52’s post-construction procedures, we must move to the second step of the Chevron analysis.
Chevron Step II. Petitioners and amicus curiae raise the possibility that, during the lengthy construction process, new information might arise casting doubt on the continuing validity of the Commission’s early findings regarding the propriety of a plant’s design or siting. They argue that such new information must be considered under § 185 when the Commission makes its final post-construction determination that a plant has been constructed and will operate in conformity with the Act. Part 52 fails on this count, they submit, because it provides no vehicle for the consideration of these new developments, but rigidly relies on past findings, requiring the Commission to find only that, since all previous licensing requirements were met, a plant is “accordingly” in compliance with the Act.
Specifically, petitioners and amicus suggest that perhaps an earthquake, tornado or flood could occur after pre-approval but before operation, raising previously unexplored questions as to the siting of the plant — questions that would go unconsidered under the Commission’s scheme. See Brief of Amicus Curiae, Committee to Bridge the Gap at 9. Likewise, an accident at a similarly configured plant could transpire, creating concerns as to the continuing viability of a plant’s design. See Brief of Petitioners at 44. See also NIRS, 918 F.2d at 195. The panel, also concerned with such scenarios, concluded that the new information potential rendered any reliance on pre-construction findings untenable, and found this a reasoned basis for requiring the NRC to rehear all material issues regarding compliance with the Act after construction. See id. at 194-97.
This argument is not, we think, based on the plain intent of Congress, but rather falls within the ambit of Chevron step II. As we have discussed above, § 185 on its face does nothing to suggest that the NRC’s reliance on prior determinations is invalid. Still, one might argue that reliance on pre-construction findings could be unreasonable, as Chevron uses that term, if the bases for these findings are drastically undermined by subsequent events.
In any event, the Commission has not ignored the problem of new information as petitioners suggest. Under §§ 52.-103(b)()(ii) and (2)(ii), any interested party may file a petition with the Commission to modify the terms of a combined license— and, thus, the acceptance criteria — even after construction is complete. The Commission is required under these provisions to determine whether “immediate action is required,” including the need to conduct additional hearings. See § 52.103(b)(2)(ii). More simply, through this vehicle anyone may raise the possibility that, given new information, the Commission's continuing reliance on settled generic findings is based on an impermissible or arbitrary reading of the Act or NRC rules.
Petitioners argue that the petition process may not be amenable to judicial review. Section 52.103(b)(2) itself incorporates the procedures of 10 C.F.R. § 2.206, which provides in part that “[a]ny person” may “file a request to institute a proceeding ... to modify, suspend, or revoke a license, or for such other action as may be proper”; should relief be denied, § 2.206 also requires the Commission to provide a written statement explaining its reasons. Petitioners point out, and the panel observed, that “courts have treated § 2.206 petitions as enforcement actions presumptively unreviewable under Heckler v. Chaney, 470 U.S. 821, 105 S.Ct. 1649, 84 L.Ed.2d 714 (1985).” NIRS, 918 F.2d at 196. Indeed, as the panel also mentioned, courts have held § 2.206 petitions unre-viewable in actions for license revocation based on the inadequacy of quality assurance programs, Safe Energy Coalition v. NRC, 866 F.2d 1473 (D.C.Cir.1989), and emergency preparedness plans. Massachusetts v. NRC, 878 F.2d 1516 (1st Cir.1989).
After additional consideration, however, we think that Commission action on § 2.206 petitions authorized by Part 52 is reviewable. True, the Commission also uses § 2.206 as a vehicle for entertaining requests for enforcement actions where, of course, the petitions do fall within the unreviewability presumption of Heckler v. Chaney. Nonetheless, the choice to use the § 2.206 form cannot determine the reviewability question. Rather, we must look to the purpose to which the petition is put. Part 52 employs § 2.206 not as a means for requesting enforcement, but as an integral part of the licensing process itself. No court to date has ever found licensing decisions to be unreviewable, even when they involve § 2.206 petitions.
By way of comparison, we recall the specifics of Massachusetts v. NRC, a case in which the Commission’s denial of a § 2.206 petition itself formed the basis of its decision to allow a facility to resume operations after a long shutdown. While noting that denials of § 2.206 petitions are ordinarily affected by the Heckler v. Chaney presumption, the First Circuit postulated that, because the reasoning set forth in the denial was the basis of the restart decisions, the substance of the denial was reviewable under 5 U.S.C. § 706(2)(A). Massachusetts v. NRC, 878 F.2d at 1522. This decision reinforces the point that the use to which a § 2.206 petition is put — not its form — governs its reviewability.
Thus, even if potential new factual information might undermine the reasonableness of the Commission’s reliance on its prior determinations, and even if the Commission reads §§ 52.103(b)(1)(h) and (2)(ii) to deny arbitrarily a meritorious petition raising such information, a court may properly intervene to adjudicate the question.
We pause here to note that when relying on prior determinations, many agencies provide mechanisms similar to § 2.206; their aim, like the Commission’s here, is to allow interested parties to prevent agency reliance on previous determinations when new information or other pertinent concerns demand special consideration. Indeed, the Supreme Court has consistently commented favorably upon these petition processes and found them perfectly adequate to protect against unforeseen contingencies such as those petitioners presuppose.
While approving an FCC rule aimed at resolving many issues regarding station license awards — despite the Commission’s statutory obligation to conduct a “full hearing” in each case — the Supreme Court in Storer Broadcasting commented that the rule “ ‘did not bind [the Commission] inflexibly to the licensing policies expressed in the Regulations.’ ” Storer Broadcasting, 351 U.S. at 205, 76 S.Ct. at 771 (quoting National Broadcasting Co. v. United States, 319 U.S. 190, 225, 63 S.Ct. 997, 1013, 87 L.Ed. 1344 (1942)). In fact, recognizing that “ ‘time and changing circumstances,’ ” could “reveal that the ‘public interest’ is not served by application of the Regulations,” the Court pointed out that the FCC had included a petition process in its “hearing” scheme so that interested parties might ask the Commission to waive its usual reliance on prior rulemaking determinations in particular cases. Id. The FCC petition rule, similar to the § 2.206 process now before us, provided:
Petition for amendment or waiver of rules. Any interested person may petition for issuance, amendment, repeal or waiver of any rule or regulation [used in lieu of a hearing on the matter]. Such petition shall show the text of the proposed rule, or its change, arid set forth the reason in support of the petition.
47 C.F.R. § 1.702 (quoted in Storer Broadcasting, 351 U.S. at 202 n. 10, 76 S.Ct. at 770 n. 10).
Indeed, the Court in Storer Broadcasting concluded that, while mandating a “full hearing,” the Act before it required no more than a general rule plus a petition process — and did so stating that, “[w]e do not think Congress intended the Commission to waste time on applications that do not state a valid basis for a hearing. If any applicant is aggrieved by a refusal, the way for review is open.” Storer Broadcasting, 351 U.S. at 205, 76 S.Ct. at 770 n. 10.
Similarly, in upholding a Federal Power Commission (“FPC”) rule designed to abbreviate the hearing process under the Natural Gas Act, the Court in FPC v. Texaco commented that “[i]n the present case, as in Storer, there is a procedure provided in the regulations whereby an applicant can ask for a waiver of the rule complained of. Facts might conceivably be alleged sufficient on their face to provide a basis for waiver,” but the petition procedures provided by the FPC were deemed perfectly sufficient to handle such a contingency. FPC v. Texaco, 377 U.S. at 40-41, 84 S.Ct. at 1109-10. The FPC petition regulation itself provided that
[a] petition for the issuance, amendment, waiver, or repeal of a rule by the Commission shall set forth clearly and concisely petitioner’s interest in the subject matter, the specific rule, amendment, waiver, or repeal requested, and cite by appropriate reference the statutory provision or other authority therefor.
18 C.F.R. § 1.7(b) (quoted in FPC v. Texaco, 377 U.S. at 40 n. 11, 84 S.Ct. at 1110 n. 11).
In Heckler v. Campbell, the Court, relying on FPC v. Texaco and Storer Broadcasting in upholding the Social Security practice of making individual eligibility decisions based on general guidelines, noted that “the regulations afford claimants ample opportunity both to present evidence relating to their own abilities and to offer evidence that the guidelines do not apply to them.” 461 U.S. at 467, 103 S.Ct. at 1957. Finally, in American Hosp. Ass’n, the Court, in approving the industry-wide NLRB rule regarding bargaining units, pointed out that the rule itself creates an exception for “extraordinary circumstances.” Ill S.Ct. at 1541.
By way of summary, the NRC’s petition process is analogous in both form and substance to those used by other agencies to ensure that their reliance on settled rules is not so insensitive to new developments that they risk creating unreasonable interpretations of statutory mandates to conduct hearings and make findings. If, in a particular circumstance, the Commission’s reliance on generic rules and prior findings proves to be an unreasonable or irrational interpretation of its statutory mandate or regulatory requirements, this court can exercise review.
To insist — as petitioners would have us do — that the Commission provide additional procedural safeguards for the consideration of new information would take us further than the Supreme Court has gone in these related eases. It would also raise severe Chevron problems. Petitioners would have us reject an agency’s interpretation of its own organic statute as unreasonable because of our differing — and hardly expert — opinion as to the likelihood and potential severity of new information. In so doing, we would not only have to reject the NRC’s petition process, but require it to address every material issue involved in the design, siting, and construction of a nuclear power plant after construction is completed — all based on our view of the potential of new information arising. To do so would take this Court across the line between our legitimate role in assuring reasonable statutory interpretations and into the illegitimate task of en-grafting additional procedural requirements onto the Commission’s regulatory process that Congress has not. See Vermont Yankee, 435 U.S. at 524, 98 S.Ct. at 1202 (“this Court has for more than four decades emphasized that the formulation of procedures was basically to be left within the discretion of the agencies to which Congress had confided the responsibility for substantive judgments”).
In closing, we add that the Commission has attempted to argue before us that § 2.206 is not merely a mechanism to reopen closed hearings and require new findings, but is also itself a hearing, albeit an informal one. Brief of Respondent at 29. The Commission has further suggested that informal hearings are acceptable under the Act, viz. § 189(a) does not prescribe formal hearing opportunities in the reactor licensing context.
Whether or not we accept that formulation, we hold that the post-construction procedures as they stand satisfy the Act. Whether or not we call § 2.206 a “hearing,” that procedure does offer a useful and prudent addition to the Commission’s licensing scheme by allowing interested parties to request the reopening of existing formal hearings. We do not follow this question any further, however, as the Commission's arguments on this score were not raised before the panel, nor advanced during the rulemaking process.
In sum, on a step II analysis, we conclude that the Commission’s post-construction reliance on prior hearings and findings is indeed grounded in a permissible understanding of the statute. Any potential new information that might arise during construction raising questions as to its reliance on previous determinations can be given adequate attention through the petition process. To require more of the Commission than this would be to ignore the Supreme Court rulings in analogous situations, the deference owed the NRC, and Vermont Yankee’s admonitions.
III.
We adopt the panel’s conclusion that Subparts A and B, as well as the combined license procedures outlined in Subpart C, are acceptable under the Act. With regard to the post-construction hearing and finding regulations, we now hold that they also are based on permissible readings of the Act. The petition for review is therefore denied, and the validity of the Commission’s Part 52 regulations upheld.
It is so ordered.
. We cannot agree with the suggestion that this Court should withhold a fully completed judicial opinion because Congress and the President may soon settle on legislation that might render it moot. See Partial Dissent of Judge Wald at 1180 (hereinafter “Partial Dissent"). We are judges engaged in the task of deciding cases as they are put to us, not political prognosticators.
. The NRC’s determinations as to what issues are material to its licensing decisions are, of course, subject to judicial review. See UCS II, 920 F.2d at 55.
. We do not, as the dissent suggests, misstate petitioners’ position as requiring a hearing after construction for any and all issues. See Partial Dissent at 1182-83. We acknowledge petitioners' concession that the Commission need not rehear immaterial issues after construction. Petitioners do insist, however, that § 189(a) of the Act provides them the right to raise every material issue of fact at every hearing in the licensing process. It is this argument that we reject, recognizing instead the Commission's power to hear argument on each material issue only once, and to consider every issue heard as settled thereafter. Indeed, UCS II’s interpretation of § 189(a) and its explanation of UCS I on this score is, we think, clear.
. Despite claims to the contrary, .see Partial Dissent at 1182, §§ 185 and 189(a) are not necessarily connected as a matter of logic. Section 185 requires post-construction findings of conformity in every case, whereas § 189(a) requires the Commission to grant a post-construction hearing only if an interested party requests one. The statute thus plainly envisions that the conformity findings might be made in the absence of a hearing.
. See also 42 U.S.C. § 2201:
In the performance of its functions the Commission is authorized to—
(i) prescribe such regulations or orders as it may deem necessary ... (3) to govern any activity authorized pursuant to this chapter, including standards and restrictions governing the design, location, and operation of facilities used in the conduct of such activity, in order to protect health and to minimize danger to life or property.
. Section 7(b) of the Natural Gas Act provides in pertinent part:
No natural-gas company shall abandon all or any portion of its facilities subject to the jurisdiction of the Commission .,. without the permission and approval of the Commission first had and obtained after due hearing, and a finding by the Commission that the available supply of natural gas is depleted to the extent that the continuance of service is unwarranted, or that the present or future public convenience or necessity permit such abandonment.
15 U.S.C. § 717f(b) (emphasis added).
. Section 9(b) of the NLRA provides:
The Board shall decide in each case whether, in order to assure to employees the fullest freedom in exercising the rights guaranteed by this subchapter, the unit appropriate for the purposes of collective bargaining shall be the employer unit, craft unit, plant unit, or subdivision thereof.
29 U.S.C. § 159(b) (emphasis added).
. The partial dissent appears to suggest that the wisdom of Part 50’s step-by-step licensing regime was endorsed by the Supreme Court in Power Reactor Dev. Co. v. International Union of Elec., Radio and Machine Workers, 367 U.S. 396, 81 S.Ct. 1529, 6 L.Ed.2d 924 (1961). See Partial Dissent at 1185. In fact, that decision merely held the Part 50 regime to be one acceptable interpretation of the Act, and did not suggest that another interpretation, such as the one now before us, would be improper. See NIRS, 918 F.2d at 193 (Wald, J.).