ML19320B448
| ML19320B448 | |
| Person / Time | |
|---|---|
| Issue date: | 06/06/1980 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Felton J NRC OFFICE OF ADMINISTRATION (ADM) |
| References | |
| NUDOCS 8007100392 | |
| Download: ML19320B448 (13) | |
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LT. LEAR PEGU: ATORY CO*.N,lSSION t
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JU.*: 0 6 ES3 MEMORANDUM FOR: Joseph M. Felton, Director, Division of Rules and Records, ADM FROM:
Harold R. Denton, Director, Office of Nuclear Reactor Regulation
SUBJECT:
REQUEST FOR TRANSMITTAL OF STATEMENT OF 15TERIM POLICY TO 0FFICE OF FEDERAL REGISTER On May 15,1980, the Commission approved a Federal Register Notice announcing a Statement of Interim Policy, on Accident Considerations Under NEPA.
Enclosed are the original Notice for Mr. Chilk's signature and 16 copies.
Please arrange for publication in the Federal Register.
The comment period will expire 90 days from the date of publication. Signed copies of letters to appropriate Congres-sional committees are also enclosed.
Please arrange for dispatch of these let-ters by the Office of Congressional Affairs. Please also request the Docketing and Service Branch, SECY, to place a copy of the Notice in the Public Document Room sinultaneously with forwarding it to the Office of the Federal Register.
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f Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosures:
Federal Register Motice s
Four ltrs to Congressional Committees D
8007100392
9 "ea.EA T _ U: ?Y CC" MISSION (10 CFR %RTS 50 TJtD 51)
Nuclear Power Plant Accident Considerations Under the !!ational Environnental Policy Act of 1959 AGENCY:
U.S. Nuclear Regulatory Commission ACTION:
Statement of Interim Policy
SUMMARY
- The Nuclear Regulatory Commission (NRC) is revising its policy for considering the more severe kinds of very low probability accidents that are physically possible in environmental impact assessments required by the National Environmental Policy Act (NEPA).
Such accidents are conmonly refer-red to as Class 9 accidents, following an accident classification scheme proposed by the Atomic Energy Commission (predecessor to NRC) in 1971 for purposes of inplementing NEPA.
The March 28, 1979 accident at Unit 2 of the Three Mile Island nuclear plant has emphasized the need for changes in NRC policies regarding the considerations to be given to serious accidents from an environmental as well as a safety point of view.
This statement of interim policy announces the withdrawal of the proposed Annex to Appendix D of 10 CFR Part 50 and the suspension of the rulemaking proceeding that began with the publication of that proposed Annex on December 1, 1971.
It is the Commission's position that its Environmental Impact State-ments shall include considerations of the site-specific. environmental impacts attributable to accident sequences that lead to releases of radiation and/or radioactive materials, including sequences that can result in inadequate cooling of reactor fuel and to melting of the reactor core.
In this regard, attention shall be given both to the probability of occurrence of such releases and to l Proposed as an Annex to 10 CFR Part 50, Appendix D, 36 FR 22851. The Commis-sion's NEPA-inplementing regulations were subsequently (July 18, 1974) revised and recast as 10 CFR Part 51 but at that time the Commission noted that "The Proposed Annex is still under consideration..." 39 FR 26279.
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l t's envircreental consecuences of such releases.
This statenent of interin policy is taken in coordination with other ongoing sa fety-related activities that are directly related to accident considerations in the areas of plant design, operational safety, siting policy, and emergency planning. The Com-mission ' intends to continue the rulemaking on this natter when new siting requirements and other safety related requirements incorporating accident considerations are in place.
DATES:
Comment period expires ADDRESSES: The Commission intends the interim policy guidance contained herein to be immediately effective. However, all interested persons who desire to submit written comments or suggestions for consideration in con-nection with this statement should send them to the Secretary of the Commis-
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sion, U.S. Nuclear Regulatory Commission, Washington, D.C.
20555, Attention:
Docketing and Service Branch.
FOR FURTHER INFORMATION CONTACT:
R. Wayne Houston, Chief, Accident Evalua-tion Branch, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, D.C.
20555, Telephone:
(301 ) 492-7323.
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UJT'i.E"OTAP.Y INFCR:'AT10":
iccident Considerations in Past NEPA Reviews The proposed Annex to Appendix D of 10 CFR Part 50 (hereafter the " Annex")
was published for connent on Decenber 1,1971 by the (forner) Atomic Energy Conmission.
It proposed to specify a set of standardized accident assunptions to be used in Environmental Reports submitted by applicants for construction permits or operating licenses for nuclear power reactors.
It also included a system for classifying accidents according to a graded scale of severity and probability of occurrence. Nine classes of accidents were defined, ranging fron trivial to very serious.
It directed that "for each class, except classes 1 and 9, the environmental consequences shall be evaluated as indicated."
Class 1 events were not to be considered because of their trivial consequences, whereas in regard to Class 9 events, the Annex stated as follows:
"The occurrences in Class 9 involve sequences of postulated successive failures more severe than those postulated for the design basis for protective systens and engineered safety features. Their consequences could be severe. However, the probability of their occurrence is so small that their environmental risk is extremely low.
Defense in depth (multiple physical barriers), quality assurance for design, manu-facture, and operation, continued surveillance and testing, and con-servative design are all applied to provide and maintain the required high degree of assurance that potential accidents in this class are, and will remain, sufficiently remote in probability that the environ-mental risk is extremely low.
For these reasons, it is not necessary to discuss such events in applicants' Environmental Reports."
A footnota to the Annex stated: 2. :.-..
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-3 "Although this annex refers to applicant's Environmental Reports, the current assumptions and other provisions thereof are applicable, except as the content may otherwise require, to AEC draft and final Detailed Statements."
During the public comment period that followed publication of the Annex a number of criticisms of the Annex were received.
Principal among these were the following:.
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1 (1) The philosophy of prescribing assumptions does no lead to objective
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(2)
It failed to treat the probabilities of accidents in any but the nost general way.
(3) No supporting analysis was given to show that Class 9 accidents are sufficiently low in probability that their consequences in terms of environnental risks need not be discussed.
(4) No guidance was given as to how accident and nornal releases of radioactive effluents during plant operation should be factored into the cost-benefit analysis.
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(5) The accident assumptions are not generally applicable to gas cooled or liquid metal cooled reactors.
(6) Safety and environmental risks are not essentially different considerations.
Neither the Atomic Energy Connission nor the NRC took any further action on this rulemaking except in 1974 when 10 CFR Part 51 was promulgated. Over the intervening years the accident considerations discussed in Environmental Impact Statements for proposed nuclear power plants reflected the guidance of the Annex with few exceptions. Typically, the discussions of accident consequences through Class 8 (design basis accidents) for each case have reflected specific site characteristics associated with meteorology (the dispersion of releases of radioactive material into the atmosphere), the actual population within a 50-mile radius of the plant, and some differences between boiling water reactors (BWR) and pressurized wate:' reactors (PWR).
Beyond these few spec-ifics, the discussi.ons have reiterated the guidance.of. the Annex and have.
relied upon the Annex's conciusion that the'proba'bilityrof occurrence ofo -
.i Class 9 event is too low to warrant consideration, a conclusion based upon generally stated safety considerations.
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ith-the Alication o f the Peactor Safety Study (tl ASH-1100), in draft forn in *ugust 1974 and final form in October 1975, the accident discussions in Environrental Impact Statenents began to refer to this first detailed study of the risks associated with nuclear power plant accidents, particularly events which can lead to the melting,of the fuel inside a reactor.2 The
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references to this study were in keeping with the intent and spirit of NEPA to 'Uisclose" relevant information, but it is obvious that WASH-1400 did not form the basis for the conclusion expressed in the Annex in 1971 that the probability of occurrence of Class 9 events was too low to warrant their (site-specific) consideration under NEPA.
The Commission's staff has, however, identified in certain cases unique circumstances which it felt warranted more extensive and detailed considera-tion of Class 9 events. One of these was the proposed Clinch River Breeder Reactor Plant (CRBRP), a liquid metal cooled fast breeder reactor very differ-ent from the more conventional light water reactor plants for which the safety.
experience base is much broader.
In the Final Environmental Statement for the CRBRP,3 the staff included a discussion of the consideration it had given to Class 9 events.
In the early site review for the Perryman site, the staff performed an informal assessment of the relative differences in. Class. 9. accident conse-quences among the alternative sites.
(SECY-78-137') !- 'i ' "H ' - _
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In the case of the application by Offshore Power Systems-to manufacture floating nuclear power plants, the staff judged that the environmental risks 2 It is of. interest that the Reactor Safety Study never refers to nor uses the tenn " Class 9 accident" although this term is commonly used as loosely equivalent to a core melt accident.
3 NUREG-0139, February 1977. __
of c: e O ass 9 events *;arranted special consideration. The special circum-stances were the potentially serious consequences associated with water (liquid) cathways leading to radiological exposures if a molten reactor core were to fall into the water body on which the plant floats. Here the staff emphasized its focus on risk to the, environment but did not find that the probat,ility of a core melt event occurring in the first place was essentially any different than for a land-based plant.
In its Memorandum and Order In the Matter of Offshore Power Systems, the Commission con urred in the staff's judgment. Thus, the Reactor Safety Study and HRC experience with these cases has served to refocus attention on the need to reemphasize that environmental risk entails both probabilities and consequences, a point that was made in the publication of the Annex, but was not g /en adequate emphasis.
In July 1977 the NRC comissioned a Risk Assessment Review Group "to clarify the achievenents and limitations of the Reactor Safety Study." One of the conclusions of this study, published in September 1978, as NUREG/CR-0400,
" Risk Assessment Review Group Report to the U.S. Nuclear Regulatory Commission,"
was that "The Review Group was unable to determine whether the absolute prob-abilities of accident sequences in WASH-1400 are high or low, but believes that the error bounds on those estimates are in general, greatly understated."
This and other findings of the Review Group have also subsequently been refer-t red to in Environmental Impact Statements, along.with a. reference <to then
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Commission's policy statement on the-Reactor Safety Study inilight' of the:
Risk Assessment Review Group Report, published on January 18, 1979. The Commission's statement accepted the findings of the Review Group, both as to the Reactor" Safety Study's achievements and as to its limitations.
4 Docket No. STN' 50-437, September 14, 1979.
a 'e v 'ra ft Envimental Staterents have Sesn published rubsequent to the Three l'ile Island accident. These were for conventional land-based ight water reactor plants and continued to reflect the past practice with respect to accidents at such plants, but noted that the experience gained from the Three Mile Island accident was not factored into the discussion.
Our experience with past NEPA reviews of accidents and the TMI accident clearly leads us to believe that a change is needed.
Accordingly, the proposed Annex to Appendix 0 of 10 CFR Part 50, published on December 1,1971, is hereby withdrawn and shall not hereafter be used by appli-cants nor by the staff. The reasons for the withdrawal are as follows:
1.
The Annex proscribes consideration of the kinds of accidents (Class 9) that, according to the Reactor Safety Study, dominate the accident risk.
2.
The definition of Class 9 accidents in the Annex is not sufficiently precise to warrant its further use in Commission policy, rules, and regulations, nor as a decision criterion in agency practice.
3.
The Annex's prescription of assumptions to be used in the analysis of the environmental consequences of accidents does not contribute to objective consideration.
4 The Annex does not give adequate consideration to the detailed treatment of measures taken to prevent and to mitigate the consequences of acci-dents in the safety review of each application.
The classification of accidents proposed in that Annex shall no longer be used.
In its place the following interim' guidance is given for the treatment of accident risk considerations in NEPA reviews.
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Accident Considerations in Future NEPA Reviews It is the position of the Conmission that its Environmental Impact Statements, pursuant to Secti$n' 102(c)(i) of the National Environmental Policy Act of 1969, shall include a reasoned consideration of the environmental risks (impacts) attributable to accidents at the particular facility or facilities within the scope of each such statement.
In the analysis and discussion of such risks, asproxir.ately er,ual
.tsntion shall be given to the probability of occurrence of releases and to the probability of occurrence of the environc. ental conse-quences of those releases.
Releases refer to radiation and/or radioactive naterials entering environmental exposure pathways, including air, water, and ground wa ter.
Events or accident sequences that lead to releases shall include but not be limited to those that can reasonably be expected to occur In-plant accident sequences that can lead to a spectrum of relaases shall be discussed and shall include sequences that can result in inadequate cooling of reactor fuel and to melting of the reactor core. The extent to which events arising from causes external to the plant which are considered possible contributors to the risk associated with the particular plant shall also be discussed. Detailed quantitative considerations that form the basis of probabilistic estimates of releases need not be incorporated in the Environmental Impact Statements but shall be referenced therein.
Such references shall include, as applicable, reports on safety evaluations.
The environmental consequences of releases whose probability of occurrence has been estimated shall also be discussed in probabilistic terms.
Such consequences shall be characterized in terms of potential radiological expo-sures to. individuals, to population groups, and,[where applicable, to _ biota. '
Health and safety' risks that may be associated ~with exposures 'to people shall*
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be discussed in a manner that fairly reflects the current state of knowledge regarding such risks.
Socioeconomic impacts that might be associated with emergency measures'during-or following an accident should also be discussed.
The environmental risk of accidents should also be compared to and contrasted with radiological risks associated with normal and anticipated operational releases. __
In cromulgating this interM pidence, the Cor-ission is a..are that there are and will likely remain for scoe time to core many uncertainties in the application of risk assessment,ethods, and it expects that its Envircncental Impact Statements will identify najor uncertainties in its probabilistic estimates.
On the other hand the Commission believes that the state of the art is sufficiently advanced that a beginning should now be made in the use
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of these methodologies in the regulatory process, and that such use will represent a constructive and rational forward step in the discharge of its responsibilities.
It is the intent of the Commission in issuing this Statement of Interin Policy that the staff will initiate treatments of accident considerations, in accordance with the foregoing guidance, in its ongoing NEPA reviews, i.e.,
for any proceeding at a licensing stage where a Final Environmental Impact Statement has not yet been issued. These new treatments, which will take into account significant site-and plant-specific features, will result in more detailed discussions of accident risks than in previous environmental statements, particularly for those related to conventional light water plants at land-based sites.
It is expected that these revised treatments will lead to conclusions regarding the environmental risks of accidents similar to those that would be reached by a continuaticq of current. practices, particularly for cases invslving special circumstances where Class 9 risks have bee'n. con ~ m sidered by the staff, as ' described above. Thus, this change in policy is
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not to be construed as any lack of confidence in conclusions regarding the environnental risks of accidents expressed in any previously issued Statements,
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nor, absent a showing of simi1ar special circumstances, as a basis for open-ing, reopening or expanding any previous or ongoing proceeding.
5 Commissioners Gilinsky and Bradford disagree with the inclusion of the preceding two sentences. They feel that they are absolutely inconsistent
- with an even-handed reappraisal of the former, erroneous position on Class 9 accidents.
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o Pc.;ever, it is also the intent of the Comissien that the staff take steps to identify additional cases that night warrant early censiderat. ion of either additional features or other actior's which would prevent w.
citigste the con-sequences of serious accidents.
Cases for such consideration are those for which a Final Environmental Statement has already been issued at the Construc-tic'1 Permit stage but for which the Operating License review stage has not yet'been reached.
In carrying out this directive, the staff should consider relevant site features, including population density, associated with accident risk in comparison to such features at presently operating plants.
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should also consider the likelihood that substantive changes in plant design i
features which may compensate further for adverse site features may be more earily incorporated in plants when construction has not yet progressed very fa r.
j Environmental Reports submitted by applicants for construction permits and for operating licenses on or after July 1,1980 should include a discussion of the environmental r *sks associated with accidents that follows the guidance given herein.
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Related Policy Matters Under C_onsideration In addition to its responsibilities under NEPA, the NRC also bears responsi-bility under the Atomic Energy Act for. the protect; ion of.the public health and safety fron'the. hazards ~ associated with the use of nuclear energy, c Pursuant to this responsibility the Commission notes that there are currently a number of ongoing activities being considered by the Commission and itis staff which intimately relate to the " Class 9' accident" question and' which are either the subject of current rulemaking or are, candidate subjects for rulemaking.....
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On %cenber 19, 1979 the Comission issuad 'ar public coment a prcoosed rule which would significantly revise its recuirements in 10 r.FP.. Part 50 for energency planning for nuclear power plants. One of the considerations in this rulemaking was the potential consequences of Class 9 accidents in a gener'c sense.
In August 1979, pursuant to the Commission's request, a Siting policy Task Force made recommendations with respect to possible changss in NRC reactor siting policy and criteria,S currently set forth in 10 CFR Part 100. As stated therein, its reconmendations were made to acconplish (among others) the following goal:
"To take into consideration in siting the risk associated with accidents beyond the design basis (Class 9) by establishing population density and distribution criteria."
This matter is currently before the Commission.
This and other recommendations that have been made as a result of the investiga-tions into the Three Mile Island Accident are currently being brought together by the Commission's staff in the form of proposed Action Plans.9 Among other matters, these incorporate recommendations for rulemaking rclated to degraded core cooling and core nelt accidents. The Commission expects to issue deci-sions on these Action Plans in the near future.
It is the Comission's policy and -intent to devote NRC's major resources to ratt.ers.which the Comission y
believes willimake existing and future nuclear power plants, safer, and to ' -
6 44 FR 75167 7 cf. NUREG-0396, " Planning Basis for the Development of State and Local Government Radiological Energency Response Plans in Support of Light Water Nuclear Power Plants," November 1978.
8 NUREG-0625, " Report of the Siting. Policy Task Force," August 1979.
9' Draft NUREG-0660, " Action Plans for Implementing Recommendations of the President's Commission and Other Studies of the TMI-2 Accident," December 10, 1979.
r prevent a recurrence of the kind of accident that occurred at Three Mile Island.
In the interim, however, and pending conpletion of rulemaking activities in the areas of emergency planning, siting criteria, and design and operational safety, all of which involve considerations of serious acci-dent potential, the Conmission finds it essential to improve its procedures for describing and disclosing to the public the basis for arriving at conclu-sions regarding the environmental risks due to accidents at nuclear power pl ants. 01 completion of the rulemaking activities in these areas, and based also upon t,he experience gained with this statenent of interim policy and guidance, the Comnission intends to pursue possible changes or additions to 10 CFR 'Part 51 to codify its position on the role of accident risks under NEPA.
Dated at Washington, D.C. this day of
- 1980, For the Nuclear Regulatory Commission i
l Samuel J. Chilk Secretary of the Commission
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JUI' O 61930 The Honorable Gary Hart, Chairman Subcornittee on Nuclear Regulation Committee on Environment and Public Works United States Senate Washington, DC 20510
Dear Mr. Chairman:
Enclosed for your information are copies of a Statement of Interim Policy, on Accident Considerations Under NEPA, which is to be published in the FEDERAL REGISTER. This statement sets forth the Commission's position that its future Environmental Impact Statements shall include considerations of the site-specific environmental impacts attributable to accident sequences that lead to releases of radiation and/or radioactive materials, including sequences that can result in inadequate cooling of the re~ ctor fuel and to a
melting of the reactor core.
Public romment on this statement is being invited during the 90 day period
- following 7ublication in the FEDERAL REGISTER.
Sincerely, M
Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosure:
Statement of Interim Policy cc: The Hon'orable Alan Simpson
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JUN 06 E0 The Honorable Morris K. Udall, Chair:nn Subcommittee on Energy and the Environment Committee ca Interior and Insular Affairs United States House of Representatives Washington, DC 20515
Dear Mr. Chairman:
Enclosed for your information are copies of a Statement of Interim Policy, on Accident Considerations Under NEPA, which is to be published in the FEDERAL REGISTER. This statement sets forth the Commission's position that its future Environmental Impact Statements shall include considerations of the site-specific environmental impacts attributable to accident sequences that lead to releases of radiation and/or radioactive materials, including sequences that can result in inadequate cooling of the reactor fuel and to melting of the reactor core.
Public comment on this statement is being invited during the 90 day period following publication in the FEDERAL REGISTER.
Sincerely, MSY Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosure:
Statement of Interim Policy cc: The Honorable Steven Symms
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JU.*i 0 6 139 The Honorable John D. Dingell, Chairman Subcommittee on Energy and Power Committee on Interstate and Foreign Commerce l
United States House of Representatives Washington, DC 20515
Dear Mr. Chairman:
Enclosed for your information are copies of a Statement of Interim Policy, l
on Accident Considerations Under NEPA, which is to be published in the FEDERAL REGISTER. This statement sets forth the Commission's position that its future Environmental Impact Statements shall include considerations of the site-specific environmental impacts attributable to accident sequences that lead to releases of radiation and/or radioactive materials, including sequences that can result in inadequate cooling of the reactor fuel and to melting of the reactor core.
Public comment on this statement is being invited during the 90 day period l
following publication in the FEDERAL REGISTER.
l Sincerely, M
l Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosure:
l Statement of Interim Policy cc: The Honorable-Clarence J. Brown
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.. j-JUN 00 1?30 The Honorable Toby Moffett, Chairman Subconmittee on Environment, Energy artd Natural Resources Comittee on Government Operations United States House of Representatives Washington, DC 20515
Dear Mr. Chairman:
Enclosed for your information are copies of a Statement of Interim Policy, on Accident Considerations Under NEPA, which is to be published in the FEDERAL REGISTER.
This statement sets forth the Commission's position that its future Environmental Impact Statements shall include considerations of the site-specific environmental impacts attributable to accident sequences that lead to releases of radiation and/or radioactive naterials, including sequences that can result in inadequate cooling of the reactor fuel and to melting of the reactor core.
Public comment on this statement is being invited during the 90 day period following publication in the FEDEPAL REGISTER.
Sincerely, MSY o--
Harold R. Denton, Director Office of Nuclear Reactor Regulation s
Enclosure:
Statement of Interim Policy cc: The Honorable Paul N. McCloskey, Jr.
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