Opinion for the Court filed by Chief Judge BAZELON.
Separate statement of Chief Judge BAZELON.
Separate statement filed by Circuit Judge TAMM, concurring in the result.
BAZELON, Chief Judge:
The problems posed in both these cases relate to the manner and extent to which information concerning the environmental effects of radioactive wastes must be considered on the public record in decisions to license nuclear reactors.
I. INTRODUCTION
Appeal number 74-1385 involves a proceeding to license a specific nuclear reactor (the Vermont Yankee Nuclear Power Station located near Vernon, Vermont). Pursuant to the National Environmental Policy Act,1 petitioners2 sought consideration of the environmental effects of that portion of the “nuclear fuel cycle”3 attributable to operation of that reactor. The Appeal Board held that Licensing Boards4 must consider the environmental effects of transportation of fuel to a reactor and of wastes to reprocessing plants, but need not consider the “operations of the reprocessing plants or the disposal of wastes” in individual licensing proceedings. In re Vermont Yankee Nuclear Power Corp., ALAB-56, 4 AEC 930 (June 6, 1972), I-J.A. 72, 76.5
Appeal number 74-1586 involves a rule-making proceeding which the Commission instituted shortly thereafter with specific reference to the Vermont Yankee decision. The purpose of the rulemaking was to reconsider whether environmental effects of [341]*341all stages of the uranium fuel cycle should be included in the cost-benefit analysis for licensing individual reactors. 37 Fed.Reg. 24191 (Nov. 15, 1972), II-J.A. 1. The Commission concluded the environmental effects of the fuel cycle, including waste disposal, were “relatively insignificant,”6 but that it was preferable to take them into account. Therefore, a rule was promulgated requiring a series of specified numerical values (set out as Table S-3 accompanying the rule) be factored into the cost-benefit analysis for an individual reactor. These values are intended to represent the incremental contribution of an additional reactor to the environmental effect of the fuel cycle. The rule further provides that in addition to Table S-3, “No further discussion of such environmental effects shall be required.” 7 Finally, it is declared that “[ijnsofar as this rule differs” from that announced in the Vermont Yankee decision, supra, that decision shall have “no further precedential significance.” Id.
II. VERMONT YANKEE (74-1385)
It is undisputed that a reactor licensing is a “major Federal actionQ significantly affecting the quality of the human environment” which requires a “detailed” environmental impact statement under § 102(2)(C) of NEPA, 42 U.S.C. § 4332(2)(C). That section requires an impact statement to consider, inter alia,
(ii) any adverse environmental effects which cannot be avoided should the proposal be implemented,
(v) any irreversible and irretrievable commitments of resources which would be involved in the proposed action should it be implemented.
The plain meaning of this language encompasses radioactive wastes generated by the operations of a nuclear power station, just as it does the stack gases produced by a coal-burning power plant.
Nor are the wastes generated by the subject reactor de minimis. We were informed at argument that the Vermont Yankee plant will produce approximately 160 pounds of plutonium wastes annually during its 40-year life span.8 Plutonium is generally accepted as among the most toxic substances known; inhalation of a single microscopic particle is thought to be sufficient to cause cancer.9 Moreover, with a half-life of 25,000 years, plutonium must be isolated from the environment for 250,000 years before it becomes harmless. Operation of the facility in question will also produce substantial quantities of other “high-level”10 radioactive wastes in the [342]*342form of strontium-90 and cesium-137 which, with their shorter, 30-year half-lives, must be isolated from the environment for “only” 600 to 1000 years.11
The Appeal Board advanced two major arguments to justify its decision that reprocessing and waste disposal issues need not be considered at the licensing stage: (1) that these issues are too speculative; and (2) that they are more appropriately considered when reprocessing and waste disposal facilities are themselves licensed. We turn now to these contentions.
The Board agreed that “there will be an incremental environmental effect ultimately resulting from the operation of this reactor as the result of the operation of whatever reprocessing and disposal grounds may from time to time be used during the life of the plant.”12 In its opinion, however, these effects were too “contingent and presently indefinable” to be evaluated at the time of licensing in view of the 40-year expected life of the reactor. The Board wrote:
It is evident to us that evaluation of the environmental effects of the operation of one or more unidentifiable reprocessing plants, employing separation processes which are unidentified and which may or may not now be known or used, during the course of the forty-year life of the plant, is not possible at this time and in this proceeding.
I-J.A. 82. This approach was decisively rejected in SIPI, supra, note 11, 481 F.2d at 1092. There we held that the obligation to make reasonable forecasts of the future is implicit in NEPA and therefore an agency cannot “shirk [its] responsibilities under NEPA by labeling any and all discussion of future environmental effects as ‘crystal ball inquiry.’ ” “Meaningful information” concerning the effects of waste reprocessing and disposal technology is presently available, see SIPI, 481 F.2d at 1094, 1096. As the Board noted, a reprocessing plant has been operated by the Commission for some time, and additional plants are under construction. I-J.A. 79. The possibility that improved technology may be developed during the 40-year life span of a reactor does not render consideration of environmental issues too speculative, as the Board appears to suggest. NEPA’s requirement for forecasting environmental consequences far into the future implies the need for predictions based on existing technology and [343]*343those developments which can be extrapolated from it.13
As more and more reactors producing more and more waste are brought into being, “irretrievable commitments [are] being made and options precluded,” see SIPI, 481 F.2d at 1094, 1098, and the agency must predict the environmental consequences of its decisions as it makes them. See Aberdeen & Rockfish R.R. v. SCRAP, 422 U.S. 289, 320, 95 S.Ct. 2336, 45 L.Ed.2d 191 (1975).
The second argument advanced by the Board is that licensing proceedings for reprocessing plants are a more “appropriate proceeding” in which to weigh the environmental effects of reprocessing and waste disposal. I-J.A. 86. Licensing of a reprocessing plant or waste disposal facility is itself a “major Federal action” affecting the environment which requires a NEPA statement. The real question posed by the Board’s opinion is whether the environmental effects of the wastes produced by a nuclear reactor may be ignored in deciding whether to build it because they will later be considered when a plant is 'proposed to deal with them. To answer this question any way but in the negative would be to misconstrue the fundamental purpose of NEPA.14 Once a series of reactors is operating, it is too late to consider whether the wastes they generate should have been produced, no matter how costly and impractical reprocessing and waste disposal turn out to be; all that remain are engineering details to make the best of the situation which has been created.15 NEPA’s purpose was to break the cycle of such incremental decision-making:
Policy is established by default and inaction. Environmental problems are only dealt with when they reach crisis proportion. . . . Important decisions concerning the use and shape of man’s environment continue to be made in small but steady increments which perpetuate rath[344]*344er than avoid the recognized mistakes of previous decades.
Senate Rep. No. 296, 91st Cong., 1st Sess. 5 (1969). Decisions to license nuclear reactors which- generate large amounts of- toxic wastes requiring special isolation from the environment for several centuries are a pardigm of “irreversible and irretrievable commitments of resources” which must receive “detailed” analysis under § 102(2)(C)(v) of NEPA, 42 U.S.C. § 4332(2)(C)(v).16 We therefore hold that absent effective generic proceedings to consider these issues, they must be dealt with in individual licensing proceedings.17
The order granting a full-term license for the Vermont Yankee plant is hereby remanded to await the outcome of further proceedings in the rulemaking, discussed hereafter.
III. RULEMAKING (74-1586)
(A.)
The notice of proposed rulemaking, 37 Fed.Reg. 24191 (Nov. 15, 1972), suggested as a possible alternative to the rule of Vermont Yankee, supra, that a series of specified numerical values (set out as Table S-3 in the notice) be factored into the cost-benefit analysis for individual reactors.18 These [345]*345values were intended to represent the incremental contribution of a hypothetical 1000 MWe model light water reactor to the total environmental effect of the uranium fuel cycle. While expressed as numerical values in Table S-3, a fair summary of the conclusions incorporated into the rule is that the environmental effects of the fuel cycle are “insignificant.”19 The notice further stated that the “supporting data for this summary table” is contained in a staff document entitled the “Environmental Survey of the Nuclear Fuel Cycle” (Nov. 6, 1972) [hereafter “Environmental Survey”], which was simultaneously made public.20
An “informal rulemaking hearing” of the “legislative-type” was scheduled to receive comments in the form of “oral or written [346]*346statements.” 21 By subsequent notice, the Commission designated a three-member hearing board to preside, and reiterated, “The procedural format for the hearing will follow the legislative pattern, and no discovery or cross-examination will be utilized.” 38 Fed.Reg. 49 (Jan. 3, 1973).22
The primary argument advanced by the public interest intervenors is that the decision to preclude “discovery or cross-examination” denied them a meaningful opportunity to participate in the proceedings as guaranteed by due process. They do not question the Commission’s authority to proceed by informal rulemaking, as opposed to adjudication. They rely instead on the line of cases indicating that in particular circumstances procedures in excess of the bare minima prescribed by the Administrative Procedure Act, 5 U.S.C. § 553, may be required.23
The Government concedes that “basic considerations of fairness may under exceptional circumstances” require additional procedures in “legislative-type proceedings,” but contends that the procedures here were more than adequate.24 Thus, we are called upon to decide whether the procedures provided by the agency were sufficient to ventilate the issues.25
A few general observations are in order concerning the role of a court in [347]*347this area. Absent extraordinary circumstances, it is not proper for a reviewing court to prescribe the procedural format which an agency must use to explore a given set of issues.26 Unless there are statutory directives to the contrary, an agency has discretion to select procedures which it deems best to compile a record illuminating the issues.27 Courts are no more expert at fashioning administrative procedures than they are in the substantive areas of responsibility which are left to agency discretion.28 What a reviewing court can do, however, is scrutinize the record as a whole to insure that genuine opportunities to participate in a meaningful way were provided, and that the agency has taken a good, hard look at the major questions before it.
We have sometimes suggested that elucidation of certain types of issues, by their very nature, might require particular procedures, including cross-examination.29 In fact, we have been more concerned with making sure that the record developed by agency procedures discloses a thorough ventilation of the issues than with what devices the agency used to create the dialogue.30
Of necessity, assessing agency procedures requires that the reviewing [348]*348court immerse itself in the record. Abstract characterizations are an unsatisfactory guide for determining what procedures are necessary in particular proceedings.31 Alternative procedural techniques are usually available, and the absence of one device, such as cross-examination, may be compensated for by the sensitive use of substitutes.32 If review is to be meaningful, it must focus on the actual operation of the whole range of procedures in a particular setting — including “context of fact, statutory framework and nature of action.”33
A prominent feature of the statutory context created by NEPA is the requirement that the agency acknowledge and consider “responsible scientific opinion concerning possible adverse environmental effects” which is contrary to the official agency position, (see, e. g., infra note 51). Committee for Nuclear Responsibility, Inc. v. Seaborg, 149 U.S.App.D.C. 380, 463 F.2d 783, 787 (1971). NEPA requires that agencies see to it that “the officials making the ultimate decision [are] informed of the full range of responsible opinion on the environmental effects in order to make an informed choice.” Id. The decision to proceed by rulemaking neither relieves the Commission of this obligation, nor permits it to depend solely on whatever contributions intervenors happen to make to develop .a fair representation of scientific opinion for the record.34
In order to determine whether an agency has lived up to these responsibil-'' ities, a reviewing court must examine the record in detail to determine that a real give and take was fostered on the key issues. This does not give the court a license to judge for itself how much weight should be given particular pieces of scientific or technical data, a task for which it is singu[349]*349larly ill-suited. It does require, however, that the court examine the record so that it may satisfy itself that the decision was based “on a consideration of the relevant factors.”35 Where only one side of a controversial issue is developed in any detail, the agency may abuse its discretion by deciding the issues on an inadequate record.
A reviewing court must assure itself not only that a diversity of informed opinion was heard, but that it was genuinely considered. “[T]he dialogue that the APA’s rulemaking section contemplates cannot be a sham.”36 Since a reviewing court is incapable of making a penetrating analysis of highly scientific or technical subject matter on its own, it must depend on the agency’s expertise, as reflected in the statement of basis and purpose, to organize the record, to distill the major issues which were ventilated and to articulate its reasoning with regard to each of them.37
An agency need not respond to frivolous or repetitive comment it receives. However, where apparently significant information has been brought to its attention, or substantial issues of policy or gaps in its reasoning raised, the statement of basis and purpose must indicate why the agency decided the criticisms were invalid.38 Boilerplate generalities brushing aside detailed criticism on the basis of agency “judgment” or “expertise” avail nothing; what is required is a reasoned response, in which the agency points to particulars in the record which, when coupled with its reservoir of expertise, support its resolution of the controversy.39 An agency may abuse its discretion by proceeding to a decision which the record before it will not sustain, in the sense that it raises fundamental questions for which the agency has adduced no reasoned answers.
(B.)
With these observations in mind, we turn to our examination of this record. The significance of Table S-3 is that it expresses in numerical terms the conclusion that the environmental effects of the fuel cycle, including waste disposal, are insubstantial.40 The primary basis for these judgments is the data assembled by the staff in the draft Environmental Survey made public with the proposed rule. The conclusions reached by the staff in the Environmental Survey were in turn adopted without modification by the Commission as Table S-3 and embodied in the final rule. Thus, support for a rule limiting consideration of environmental issues to the numbers in Table S-3 must be found in one of three places: the Environmental Survey, the back-up documentation to which it refers, and the oral and written testimony offered at the hearing. It is to these sources we must look for a thorough ventilation of the underlying issues.
The Environmental Survey made public prior to the hearing was intended to “provideQ a basis for an informed consideration of the . . environmental impact associated with the uranium fuel cycle [and to] contain[] extensive references to background documents available to members of the public.” 38 Fed.Reg. 49 (Jan. 3, [350]*3501973). Regarding most phases of the-fuel cycle, these promises were fulfilled and the Environmental Survey did an adequate, even admirable job, of describing the processes involved. It assembles data on the consumption of resources, and discusses the risks of accidents and other hazards in detail, supporting the staffs conclusions with numerous references to the scholarly literature and to technical reports on file with the Commission. However, with regard to the two phases of the fuel cycle which are the focal points for this appeal, reprocessing and waste disposal,41 that kind of detailed explanation and support for the staff’s conclusions was noticeably absent from the Environmental Survey as originally published.
The only discussion of high-level waste disposal techniques was supplied by a 20-page statement by Dr. Frank K. Pittman, Director of the AEC’s Division of Waste Management and Transportation. This statement, delivered during the oral hearings, was then incorporated, often verbatim, into the revised version of the Environmental Survey published after the comment period42 Dr. Pittman began his statement by acknowledging that he was “broadly involved” with the subject of high-level waste management since he heads the division of the AEC charged with “responsibility for the development, construction and operation of facilities for ultimate management of commercial high-level waste.”43
Dr. Pittman proceeded to describe for the first time in public the “design concepts” for a federal surface repository for retrievable storage of high-level waste.44 This is essentially a warehouse in which sealed canisters containing cylinders of solidified nuclear wastes can be stored in water-filled basins recessed into the ground on a temporary basis (up to 100 years), until such time as a permanent waste disposal scheme is devised, when they can be removed.45 While the “intended life” of the facility is only 100 years, some high-level wastes must be isolated for up to 250,000 years. See supra p. 341 of 178 U.S.Ápp.D.C., 638 of 547 F.2d. Therefore, the Environmental Survey states, without further explanation, that in the future a “permanent” Federal repository for “geologic storage of high-level wastes” will be established and that the “Federal government will have the obliga[351]*351tion to maintain control over the site in perpetuity.’’ II-J.A. 724 [emphasis added].
Until recently the AEC planned to dispose of wastes by burying them deep inside abandoned salt mines. These plans were postponed indefinitely after a series of technical difficulties, including the discovery the salt mines might be susceptible to underground flooding. The Revised Environmental Survey devotes two sentences to recounting how prior waste disposal plans fared:
It was planned to construct a Federal repository in a salt mine for long-term geological storage of solid high-level wastes by the mid 1970’s. However, subsequent events have deferred the site selection and construction of such a facility.
II-J.A. 724. The “subsequent events” which led to the shelving of the salt mine plan are not discussed.46
Dr. Pittman’s description of the new plan — now also postponed indefinitely47 — to build a surface storage facility can only fairly be described as vague, but glowing. He begins:
I hope I will be able to allay what I feel are unwarranted fears and show that the bugaboo of waste management cannot logically be used as a rationale for delays in the progress of an essential technology for meeting our growing power demands.
* * * * * *
[T]here are available today proven methods for managing the high-level waste from the nuclear industry in a way which will assure first that man will not be adversely affected by the radioactivity either by external or internal contact with the waste itself or by exposure to the penetrating radiation which it generates, and second that the environment [sic] effects will be very small.
II-J.A. 59-60. In less than two pages, he set out a very general description of what the facility is supposed to do, II-J.A. 63-66, accompanied by several schematic drawings. These show the facility will have a cooling system, a transfer area and storage basins, but do not attempt to describe how they will be built and operated, what mate[352]*352rials will be used, where such a facility might be located, or what it might cost to build and operate.
Dr. Pittman then explains that “the major factor in the design of the repository for high-level waste is the technique used to remove the heat from the waste.” II-J.A. 63. Decaying radioactive waste spontaneously gives off substantial heat and “[sjhould adequate provisions not be made to remove this heat . . . , the waste and the canister would melt.” Id. A “meltdown” would result in what Dr. Pittman calls a “situation of considerable concern,” which would involve the “loss of some fraction of the isolation of the radioactive material from the environment.” II-J.A. 65. No attempt is made to describe how serious a radioactivity hazard would be presented.
In a paragraph which is carried over verbatim in the Revised Environmental Survey, II-J.A. 726, Pittman states:
The Commission has carried out extensive evaluations of safety, reliability, operability, maintainability and economics of various methods for removing heat, and has essentially narrowed the area for further study to techniques using either water or air as the heat transfer medium.
II-J.A. 64. No citations are given for these studies; in fact, there are no references to back-up materials supporting any of Pittman’s statement, or those portions of the Revised Environmental Survey drawn from it.48
Again without benefit of details, Dr. Pittman offers conclusory reassurances that the proposed facility will be designed so that the possibility of a “meltdown” can be dismissed as “incredible”:
The probability of this situation occurring is prevented by a combination of engineered features including, (i) redundancy of power supply and other essential cooling systems; (ii) structural strength to withstand credible forces of nature— earthquake, tornado, etc.; (iii) combination of structural strength, plant security, etc., to withstand credible overt forces of man; (iv) modular basin cell construction which limits the number of canisters subject to a single catastrophic event.
Thus, before a meltdown could occur, it would be necessary to have a series of failures of systems which will be engineered, constructed, and operated for maximum reliability under rigorous quality assurance programs before a situation could occur where sufficient water could not be added to and maintained in the cell to keep it from leaking or boiling dry. The timing for such a series of failures to result in uncorrectable situations is important. The individual failure of power systems for circulating the coolant would not result in pool water boiling for at least 16 hours. Various corrective actions may be taken any time within a week which would prevent cell water from boiling away. After the complete loss of water, an additional day would be required before the waste would begin to [353]*353melt. The number of sequential failures required of highly reliable systems, combined with the long time periods available for repair and recovery from each, result in the judgment that this is an incredible incident.
II-J.A. 65-66. His unadorned conclusion is in turn incorporated verbatim into the Revised Environmental Survey.49
Other than the broad reference to “structural strength, plant security, etc., to withstand credible overt forces of man”, there is no discussion of how the facility would be protected from terrorism.50 While Dr. Pittman says “[vjarious corrective actions” might be taken to prevent a meltdown, none are specified.
Dr. Pittman concludes with the judgments that:
(1) the program being followed by the industry under AEC regulation and by the AEC offers assurance that the commercial high-level waste will be managed safely from its initial production; (2) the surface storage method, to be used by the AEC, is good for as long as adequate human surveillance and maintenance effort is continued; (3) the probability that work currently under way will demonstrate the use of bedded salt as a safe, acceptable, ultimate disposal method within the next ten to fifteen years is very high; (4) should bedded salt not prove to be acceptable other acceptable geologic disposal concepts offer reasonable probability of reaching a point of acceptability within two or three decades; and (5) the waste in initial storage will be easily retrievable for either near- or far-term disposal methods when they are developed.
II-J.A. 82. There is no discussion of how “adequate human surveillance and maintenance” can be assured for the periods involved, nor what the long-term costs of such a commitment are, nor of the dangers if surveillance is not maintained.51 Nor is [354]*354any explanation offered for Dr. Pittman’s optimism regarding bedded salt as a disposal method, since the problems which have surfaced and delayed that program are not mentioned.52 Nor does the statement anywhere describe what “other acceptable geologic disposal concepts” are under consideration.
Based on Dr. Pittman’s statement, the Revised Environmental Survey concludes that the resources consumed in waste storage will be minimal, that “under normal conditions” no radioactivity will be released, and that the possibility of a serious accident is “incredible.”53 In short, based on the information in Dr. Pittman’s statement, the Commission concluded that the future environmental effects from the disposal of high-level nuclear wastes are negligible. This conclusion is in turn embodied in Table S-3, and further consideration of the issue terminated.
We do not dispute these conclusions. We may not uphold them, however, lacking a thorough explanation and a meaningful opportunity to challenge the judgments underlying them. Our duty is to insure that the reasoning on which such judgments depend, and the data supporting them, are spread out in detail on the public record. Society must depend largely on oversight by the technically-trained members of the agency and the scientific community at large to monitor technical decisions. The problem with the conclusory quality of Dr. Pittman’s statement — and the complete absence of any probing of its underlying basis — is that it frustrates oversight by anyone: Commission, intervenors, court, legislature or public. Given the opportunity, Dr. Pittman might have provided convincing answers to many of the questions which his statement leaves untouched. Since that did not occur, however, his judgments must either be accepted at face value, or rejected out of hand.
Although the vagueness of the presentation regarding waste disposal made detailed criticism of its specifics impossible, see IIJ.A. 257, the public interest intervenors did offer a number of more general comments concerning the Commission’s approach. They criticized the Commission for a general “failure to distinguish between design objectives on the one hand and performance on the other,” II-J.A. 124, noting that no consideration had been given actual experience with storage of wastes generated by weapons production. II-J.A. 272-74. They also questioned confident assertions by the AEC that long-term waste management is feasible, laying particular stress on the immense time periods involved which mock human institutions:
Except for the storage of liquid wastes in tanks, for which experience from weapons production applies, all proposals for long term storage or disposal of high level waste from the nuclear power industry lie at the research and development stage.
* * * sf: * 4:
The impression is inescapable, in view of the present imprecise state of affairs, that no convincing statements exist regarding the long term environmental impact attending the storage and/or disposal of wastes from fuel reprocessing.
* * sf: * * :}:
The times during which radioactive wastes must remain secure from the biosphere have no parallel in human affairs. Eight hundred years are required for fission products alone and millions of years if the fission products continue to be contaminated with transuranic elements at present levels. Fission technology requires that man issue guarantees on events far into the future, and it is not clear in most cases how this can be done. Institutional arrangements do not exist and never have existed'to guarantee the [355]*355monitoring of or attendance upon storage facilities over a millennium. In the range of a million years, serious geological uncertainties arise and even the survival of man may be doubtful. “In perpetuity” has little real meaning in human affairs.
II-J.A. 261-2. They reiterated repeatedly that the problems involved are not merely technical, but involve basic philosophical issues concerning man’s ability to make commitments which will require stable social structures for unprecedented periods.54
The intervenors pointed out that storing wastes aboveground places a premium on stable human institutions for monitoring and surveillance, II-J.A. 275-76; that until plans for long-term disposal in the salt beds at Lyons, Kansas fell through, see supra note 46, the agency had itself rejected the idea of surface storage because of the surveillance problems. II-J.A. 210-11, 287-89.
After reviewing the record, the presiding hearing board isolated several areas of controversy which it felt ought to be addressed by the Commission in issuing the proposed rule. Included were the adequacy of the discussion of waste disposal systems,55 and the need for fuller background documentation. II-J.A. 498.
The Commission disposed of these issues summarily in its statement of basis and purpose accompanying the promulgation of the rule without attempting to articulate responses to any of the points which had been raised regarding waste disposal:
Considerable information was presented at the hearing on high level waste storage utilizing a retrievable surface storage facility. A description was given of such facility, the normal radiological effluents, and a maximum credible accident.
Sfc * J(< * * *
While such a waste storage facility has not been constructed, preliminary conceptual designs have been developed using existing technology based on well established data and techniques.
The Commission believes that the Survey and hearing record provide an adequate data base for the regulation adopted.
39 Fed.Reg. 14189 (April 22, 1974); II-J.A. 507.1 [unnumbered page following 507].56 Thus, to the limited extent that any give- [356]*356and-take was fostered on the nuclear waste issues, the Commission, in its final decision, failed to address major contentions that were raised.
(C.)
In substantial part, the materials uncritically relied on by the Commission in promulgating this rule consist of extremely vague assurances by agency personnel that problems as yet unsolved will be solved. That is an insufficient record to sustain a rule limiting consideration of the environmental effects of nuclear waste disposal to the numerical values in Table S-3. To the extent that uncertainties necessarily underlie predictions of this importance on the frontiers of science and technology, there is a concomitant necessity to confront and explore fully the depth and consequences of such uncertainties. Not only were the generalities relied on in this case not subject to rigorous probing — in any form — but when apparently substantial criticisms were brought to the Commission’s attention, it simply ignored them, or brushed them aside without answer. Without a thorough exploration of the problems involved in waste disposal, including past mistakes, and a forthright assessment of the uncertainties and differences in expert opinion, this type of agency action cannot pass muster as reasoned decisionmaking.57
Many procedural devices for creating a genuine dialogue on these issues were available to the agency — including informal conferences between intervenors and staff, document discovery, interrogatories, technical advisory committees comprised of outside experts with differing perspectives, limited cross-examination, funding independent research by intervenors, detailed annotation of technical reports, surveys of existing literature, memoranda explaining methodology. We do not presume to intrude on the agency’s province by dictating to it which, if any, of these devices it must adopt to flesh out the record. It may be that no combination of the procedures mentioned above will prove adequate, and the agency will be required to develop new procedures to accomplish the innovative task of implementing NEPA through rulemaking. On the other hand, the procedures the agency adopted in this case, if administered in a more sensitive, deliberate [357]*357manner, might suffice.58 Whatever techñiques the Commission adopts, before it promulgates a rule limiting further consideration of waste disposal and reprocessing issues, it must in one way or another generate a record in which the factual issues are fully developed.
Our colleague, concurring spedally, expresses the view that there is “lit-tie to be gained other than delay” by remanding for additional proceedings, since it is “almost inevitable” that the Commission will reach the same result “after fully considering the problems and alternative methods of waste disposal.”59 Even if true, that would only supply an additional reason to require the Commission to acknowledge the risks and problems, as well as lay bare its own reasoning. Agencies are less likely to persist in the face of information publicly exposing the fallacies, if any, in their position. In any event, NEPA does not guarantee a particular outcome on the merits; rather, the statute mandates only a “careful and informed decisionmaking process”' to enlighten the decisionmaker and the public.60 In the rulemaking context, that requires the Commission to identify and address information contrary to its own position, to articulate its reasoning and to specify the evidence on which it relies.61 The Commission may well reach the same conclusion on remand. But if it does so on such a record, the Congress, the courts, and the public will all know where we stand.
[358]*358It has become a commonplace among proponents of nuclear power to lament public ignorance.62 The public — the “guinea pigs” who will bear the consequences of either resolution of the nuclear controversy — is apprehensive. But public concern will not be quieted by proceedings like the present.
I know no safe depository of the ultimate powers of the society but the people themselves; and if we think them not enlightened enough to exercise their control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion.63
* Sfc Sfc # * if!
The Commission’s action in cutting off consideration of waste disposal and reprocessing issues in licensing proceedings based on the cursory development of the facts which occurred in this proceeding was capricious and arbitrary. The portions of the rule pertaining to these matters are set .aside and remanded.64
Separate Statement of Chief Judge BAZELON:
I add a word of my own on some of the broader implications of Judge Tamm’s concurrence.
I agree that courts should be reluctant to impose particular procedures on an agency. For example, requiring cross-examination in a rulemaking proceeding is radical therapy, which may cause the patient to suffer a slow, painful death. “There is a not insignificant potential for havoc [which is] likely to be disproportionate to the values achieved . . . .” International Harvester Co. v. Ruckelshaus, 155 U.S.App.D.C. 411, 478 F.2d 615, 631 (1973). But I reject the implication that any techniques beyond rudimentary notice and comment are needless “over-formalization” of informal rulemaking. Concur at 363 of 178 U.S.App.D.C., 660 of 547 F.2d. Unhappily, no such bright line can be drawn between rulemaking and adjudicatory proceedings.1
[359]*359The purpose of rulemaking was to allow public input on policy, whereas adjudication was designed to resolve disputed facts. See supra note 1. However, in response to the “paralysis” of the administrative process in the last decade, rulemaking has been expanded into fact-intensive areas previously thought to require adjudicatory procedures.2 Administrative proceedings are now common which do not fit neatly into either the rulemaking or adjudicatory category. These new proceedings are “hybrids” in the sense that involve issues of general applicability which can be treated efficiently only in generic proceedings, but nonetheless involve factual components of such relative importance that a greater assurance of accuracy is required than that which accompanies notice and comment procedures.3
The need for reliable fact-finding does not necessarily imply transplanting trial-type procedures. Factual issues in hybrid proceedings tend to be complex scientific or technical ones involving mathematical or experimental data, or other “legislative facts”4 peculiarly inappropriate for trial-type procedures. Agencies should innovate procedural formats responsive to the new problems created by hybrid rulemaking. Some agencies (such as FDA and EPA) have already begun to do so.5
[360]*360Decisions in areas touching the environment or medicine affect the lives and health of all. These interests, like the First Amendment, have “always had a special claim to judicial protection.”6 Consequently, more precision may be required than the less rigorous development of scientific facts which may attend notice and comment procedures.
Despite the controversy surrounding the proper standard of review in informal rule-making cases, see Concur at n. 2, there is less disagreement on this essential point than meets the eye. With customary perspicacity, Judge Friendly has observed that often it does not really matter much whether a court says the record is remanded because the procedures used did not develop sufficient evidence, or because the procedures were inadequate.7 From the standpoint of the administrator, the point is the same: the procedures prescribed by § 553 will not automatically produce an adequate record. Thus, although Judge Tamm vehemently opposes the concept of procedural review of informal rulemaking, he agrees to send this case back for a fuller development of the facts even though the dictates of § 553 were followed.8
Of course, important differences remain from the standpoint of a reviewing court. I am convinced that in highly technical areas, where judges are institutionally incompetent to weigh evidence for themselves, a focus on agency procedures will prove less intrusive, and more likely to improve the quality of decisionmaking, than judges “steeping” themselves “in technical matters to determine whether the agency has exercised a reasoned discretion.” See Ethyl Corp. v. EPA, 176 U.S.App.D.C. 373, 541 F.2d 1, No. 73-2205 (1976) (en banc) (Bazelon, C. J., concurring), cert. denied, 426 U.S. 941, 96 S.Ct. 2663, 49 L.Ed.2d 394 (1976).9