ML20154G623
| ML20154G623 | |
| Person / Time | |
|---|---|
| Issue date: | 05/05/1988 |
| From: | Jordan E Committee To Review Generic Requirements |
| To: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| Shared Package | |
| ML20153F028 | List: |
| References | |
| NUDOCS 8805250009 | |
| Download: ML20154G623 (30) | |
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May 5, 1958 M
MEMORANDUM FOR:
Victor Stello, Jr.
Executive Director for Operations FROM:
Edward L. Jordan, Chairman Comittee tr Review Generic Requirements
SUBJECT:
MINUTES OF CRGR MEETING NUMBER 134 The Comittee to Review Generi Requirements (CRGR) met on Monday, April 18, 1988, from 1:00 p.m. to 5:30 p.m., and in subsequent sessions on April 19, 21, and 22, to review a proposed Generic Letter providing guidance to licensees for performance of the Individual Plant Examinations called for in the Comis-sion's Severe Accident Policy Statement.
A list of attendees during these meeting sessions is attached (Enclosure 1).
The Comittee recomended in favor of issuing promptly the proposed Generic Letter, subject to several substantive modifications, and a number of minor wording changes that are to be coordinated with the CRGR staff.
A revised IPE Generic Letter package, reflecting all of the recommended chan.ges, is to be reviewed by the CRGR Chairman before forward-ing to the E00 and Co:amission for final consideration.
This matter is discussed in Enclosure 2.
Additional coments by individual CRGR members, R. Bernero and C. Paperiello, are appended as a part of the minutes of Meeting No.134, in accordance with the provisions of Section IV.O. of the CRGR Charter.
In accorde.nce with the E00's July 18, 1983 directive concerning "Feedback and Closure on CRGR Reviews," a written response is required from the cognizant office to report agreement or disagreement with CRGR recomendations in these minutes.
The response, which is required within five working days after receipt of these meeting minutes, is to be forwarded to tha CRGR Chairman and if there is disagreement with the CRGR recomendations, to the EDO for decisionmaking.
Questions concerning these meeting minutes should be referred to Jim Conran (492-9855).
Wa d f
r an, Chairman Comitte to Review Generic Requi'ements
Enclosures:
As stated cc:
See next page R\\
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Commission (5)
SECY Office Directors Regional Administrators CRGR Members W. Parler T. Speis B. Sheron W. Morris Distribution: w/o enc 1.
Central File PDR (NRC/CRGR)
S. Treby W. Little M. Lesar B. Doolittle (w/ enc.)
CRGR SF (w/ene.)
M. Taylor (w/ene.)
E. Jordan (w/ enc.)
J. Heltemes (w/ene.)
J. Conran (w/ enc.)
C."Sakenas-(w/ enc.)-
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DATE : 5/f788 5/ /88 5/3 /88 OFFICIAL RECORD COPY
f ATTENDANCE LIST CRGR MEETING NO. 134 April 18, 1988 CRGR E. Jordan R. Bernero C. Paperiello D. Ross J. Sniezek J. Scinto OTHERS J. Heltemes J. Conran C. Sakenas E. Beckjord B. Sheron T. Speis F. Eltawila F. Cofiman M. Federline K. Carr F. Gillespie C. Thomas T. Cox W. Minners J. Chen W. Beckner C. Ader C. Tinkler D. McPherson E. Doolittle T. Murley S. Weiss J. Murphy G. Taylor M. Taylor G. Quittschreiber J. Larkins i
1
, to the Minutes of CRGR r cting No.134 CRGR Review of Proposed Generic Letter on IPEs April 18,19, 21 & 22,1988 TOPIC Representatives of two co-sponsoring program offices (RES & NRR) presented for CRGR review a proposed Generic Letter providing guidance to licensees on the performance of the Individual Plant Examinations (IPEs) called for in the Commission's Severe Accident Policy.
E. Beckjord (RES) and T. Murley (NRR) provided introductory remarks, and supplementary comments during the several days of the Committee's review of the IPE matter, summarizing the staff's approach and objectives in undertaking now the overall IPE effort, and setting the tone and the course of that affort.
T. Sp91s (RES), O. Sheron (RES) and F. Coffman (RES) were the principal presenters of the staff's detailed descrip-tions of the approved methodologias that can be employed by licensees in per-forming IPEs, and the important features of the staff's current plans for NRC review and application of IPE results (e.g., criteria / guidance for review of IPEs; resource requirements and schedules for the planned IPE review effort; criteria for evaluation of the possible need for IPE-related backfitting).
Copies of the slides used by the staff to guide their presentations and dis-cussions with the Committee at this meeting are enclosed (see Attachment 1 to this Enclosure).
BACKGROUND A.
The documents submitted initially for CRGR review by the co-sponsoring offices (RES & NRR) were transmitted by memorandum dated March 3C,1988, E. S. Beckjord/T. E. Murley to E. L. Jordan; that review package included the following documents:
1.
Draft Predecisional Generic Letter, dated March 25, 1988, "Individual Plant Examination for Severe Accident Vulnerabilities -
10CFR50.54(f)," with appendices and attachments as follows:
Appendix 1 - Guidance on the Examination of Containmer.: System a.
Performance (Back-End Analysis) b.
Appendix 2 - Criteria for Selecting Important Severe kcident Sequences c.
Appendix 3 - Accident Management d.
Appendix 4 - Documentation e.
Appendix 5 - Decay Heat Removal Vulnerability Insights
- f. - NUREG/CR-4920, "Asse5rment of Severe Accident Prevention and Mitigation Features (5 Volumes)
Vol. 1, "8WR Mark I Containment Design"
e...
Vol. 2, "BWR Mark II containment Design" Vol. 3, "BWR Mark III Containment Design" Vol. 4, "PWR Large Dry Containment Design Vol. 5, "PWR Ice Condenser Containment Design
- g. - List of References of the IDCOR Program Reports and Key NRC Reports 2.
Draft Evaluation (undated) of the IDCOR IPEM for BWR 3.
Draft Evaluation (undated) of the IDCOR IPEM for PWR B.
Several additional documents were provided subsequently (just before the meeting, and during the Committee's consideration of the IPE proposals at this meeting) by RES/NRR for CRGR review:
1.
Memorandum dated April 15, 1988, B. Sheron to E. Jordan, with attachments as follows:
a.
Information Required by CRGR Charter,Section IV.B., "Contents of Packages Submitted for CRGR Review" b.
NRC Staff's Formal Response to CRGR Comments in Meeting No. 125 Regarding IPE Areas Needing Improvement or Clarification (See Attachment 2 to this Enclosure.)
2.
Revisions, dated April 15, 1988, to the proposed Generic Letter (pp.
1, 2, 9, & 10) and Appendix 4 (p. 2)
(See Attachment 3 to this Enclosure.)
C.
The CRGR staff obtained and provided to the Committee the following documents for information/ consideration during their review of the IPE package at this meeting:
ltemorandum, dated March 1, 1988. E. Beckjord to V. Stello, forwarding a memorandum, dated March 1,1988, T. Speis to D. Ross et al, "Commis-sion Paper on Integrated Approach to Implementing the Commission's Policy on Severe Accidents," with an attached draft outline (undated) of Proposed Commission Paper on Integrated Approach to... Severe Accidents (See Attachment 4 to this Enclosure.)
CONCLUSIONS /RECOMENDATIONS As a result of their review of the IPE matter, including the extended discus-sions with the staff at this meeting, the Committee recommended in favor of promptly issuing the proposed Generic Letter, to begin the IPE process as called for in the Commission's Severe Accident Policy Statement.
However, the Committee attached the following caveats / conditions to their endorsement of this proposal:
1.
More detailed staff review criteria and licensee guidance (both for the "front end" and "back end" of the IPE analyses) are needed.
These criteria and guidance require review by CRGR and issuance by the staff before the clock is started on the licensee response period specified in the generic letter, but need not delay issuance of the generic letter.
Further, after issuance of the additional guidance and staff review criteria, the staff should conduct one or more workshops to assure a proper understanding of the guidance and review criteria, and to fully ventilate licensees' questions.
The end result should be guidance and review criteria that, as a package, allows for a clear and mutual understanding by licensees and the staff.
2.
The staff should seek volunteers among the several licensees whose plants have already been extensively analyzed (e.g., the NUREG-1150 plants, or other plants that have completed a good, full-scope PRA) to participate with the staff in an expedited implementation of the complete IPE process in accordance with the Generic Letter.
This would include submittal of IPE results by the licensees and trial implementation of the staff's IPE review / decision process for determining acceptability of the IPE and adequacy of the licensees' identification of outliers and proposed modi-fications.
The results of these lead plant IPEs, as well as the details of the staff's IPE review and resulting regulatory determinations, should be made available to other licensees as soon as possible.
Further, the results of this trial implementation should be reflected through issuance of revised guidance, as appropriate, and perhaps additional workshop (s).
3.
The proposed Generic Letter should be modified to indicate that External Events will be addressed separately from (rather than a deferred part of) the IPEs.
Because the treatment of external events in PRAs inherently involves much greater uncertainties than internal events, the Committee believes that treating them separately, outside the scope of the IPEs, would be a more efficient use of licensee and staff resources.
The staff should explicitly suggest in the Generic Letter, however, that licensees document plant specific data relevant to external events, developed in the course of their IPE (e.g., in plant walkdowns), such that it can be readily retrieved in a convenient form when needed for later external event analyses that may be required.
Because of the significant policy issue involved, the separation of External Events from the intended scope of the IPEs should be called explicitly to the attention of the Commission by the staff.
4.
The SERs for the IDCOR IPEH (for both BWRs and PWRs), which specify the "enhancements" that are required by the staff for IPEM acceptability, should not be issued in final form until reviewed by CRGR.
The CRGR review should be completed in conjunction with the review of more detailed criteria and guidance in item 1 above, l
5.
The wording of the proposed Generic Letter should be revised to emphasize that, as the results of the IPE are affirmed by the licensee, such results should be used to revise, for example, emergency operating procedures and training.
Licensees should not wait for issuance of generic Severe Accident Management guidance by NRC to take clearly indicated (plant-specific) actions that could Significantly improve their severe accident response capability.
6.
The draft NUREG/CR-4920 reviewed by the CRGR was found to be poorly developed and inadequately reviewed by the staff, as evidenced by inconsistencies and comments easily misunderstood as requirements.
Attempts by the Committee to perform a detailed review of this planned enclosure to the IPE Generic Letter were difficult and time consuming.
NUREG/CR-4920 should be decoupled from the Generic Letter and issued separately after further staff review.
This set of documents is not considered essential by the Comittee for initiation of the IPEs, but should be issued expeditiously, for infctmation, to provide the licensees useful Severe Accident insights that have been gained through previous PRAs and other studies.
The CRGR provided coments as examples of areas that may mislead licensees such as the discussion on venting.
These documents may be issued as a contractor report separate from the IPE Generic Letter without further CRGR review.
7.
Numerous specific clarifying changes to the wording of the proposed IPE Generic Letter and Appendices, that were discussed with and agreed to by the staff during the Committee's review of the IPE package, should be incorporated by the staff and coordinated with the CRGR staff.
The staff should provide a revised IPE Generic Letter package, reflecting the recommendations above, to the CRGR Chairman for final review prior to sending it forward for final consideration.
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CRGR REVIEW MEETING ON THE IMPLEMENTATION PLAN FOR THE SEVERE ACCIDENT POLICY STATEMENT INDIVIDUAL PLANT EXAMINATION (IPE)
GENERIC LETTER BRIAN Y. SHERON, DIRECTOR DIVISION OF REACTOR AND PLANT SYSTEMS OFFICE OF NUCLEAR REGULATORY RESEARCH APRIL 18,1988 1
Attachment I to Enclosure 2
GENERIC IEITER CONCERNING INDIVIDUAL PIANT EIAMINATION FOR SEVERE ACCIDENT VULNERABIllTES 1.
SUMMARY
2.
EXAMINAT[0N PROCESS 3.
EXTERNAL EVENTS (DEFERRED ITEM) 4.
METHODS OF EXAMINATION 5.
RELATIONSHIP TO USI A-45 6.
BENEFITS OF PRA 7.
SEVERE ACCIDENT SEQUENCE SELECTION
, S.
SEVERE ACC' DENT MANAGEMENT 9.
SEVERE ACCIDENT PREVENTION AND MITIGATION FEATURES REPORTS
- 10. DOCUMENTATION OF FJAMINATION RESULTS
- 11. LICENSEE RESPONSE
- 12. REGULATORY BASIS APPENDIX 1, GUIDANCE ON TiiE EXAM] NATION OF CONTAINMENT SYSTEMS PERFORMANCE (BACK-END ANALYSIS)
APPENDIX 2, CRITERIA FOR SBLECTING IMPORTANT S8 VERB ACCID 8NT SEQUBNCE APPENDIX 3, ACCfDENT MANAGFMENT APPENDIX 4, DOCUMENTATION APPENDIX 5, DECAY HEAT REMOVAL VULNERAB13TY INSIGHTS NITACllMENT 1, NUREG/CR-4920 ATTAcilMENT 0, LIST OF REFERENCES 2
- 1.
SUMMARY
o A 10 CFR 50.54(f) IIITER REQUESTING THE INDIVIDUAL PLANT EXAMINATIONS FROM ALL LICENSEES HOLDING OPERATING IJCENSES AND CONSTRUCTION PERMITS FOR NUCLEAR POWER PLANTS o BASIS FOR REQUESTING INDIVIDUAL PLANT EXAMINATIONS IS THE COMMISSION SEVERE ACCIDENT POLICY ISSUED ON AUGUST 8,1985 (50 FR 32138)
- PLANT SPECIFIC PRAs EXPOSED RELATIVELY UNIQUE VULNERABILITIES TO SEVERE ACCIDENTS
- THE UNDESIRABLE RISK FROM THESE UNIQUE FEATURES HAS DEEN REDUCED BY LOW-COST CHANGES VIA PROCEDURES OR MINOR DESIGN MODIFICATION
- ANALYSIS FILL DE MADE OF ANY PLWT THAT IIAS NOT YET UNDERGONE AN APPROPRIATE EXAMINATION WilEN NRC AND INDUSTRY SUFFICIENTLY PROGRESSED TO DEFINE TIIE SETHODS OF ANALYSIS o SINCE ISSUANCE OF THE POLICY STATEMENT THE STAFF INTERACTED EXTENSIVELY WITH INDUSTRY AND DEVELOPED APPROPRIATE DOCUMENTATION FOR TIIE IPEs o PURPOSE OF IPE IS FOR TIIE UTILITIES TO:
- IDENTIFY / UNDERSTAND FIIE MOST IJKELY SEVERE ACCIDENT SEQUENCES THAT COULD OCCUR AT TIIEIR PLANTS;
- EVALUATE / IMPLEMENT MEANS FOR IMPROVEMENTS
- DEVELOP AN AWARENESS FOR SEVERE ACCIDENT BEIIAVIOR 3
l
- 2. EXAMINATION PROCESS o LICENSEE'S STAFF SHOULD PARTICIPATE IN ALL ASPECTS OF THE IPE S0 THAT KNOWLEDGE GAINED BECOMES AN INTEGRAL PART OF UPERATING, TRAINING AND PROCEDURE PROGRAM.
o LICENSEES SHOULD CONDUCT SYSTEMATIC EXAMINATION OF PLANT DESIGN, OPERATION, MAINTENANCE AND EMERGENCY OPERATION T0:
- IDENTIFY PLtNT SPECIFIC VULNERABILITIES (DESIGN AND PROCEDURAL) TO SEVERE ACCIDENTS (FOR BOTH CORE DAMAGE AND CONTAINMENT PERFORMANCE); BOTH INTERNAL AND EXTERNAL INITIATORS ARE TO BE CONSIDERED (EXTERNAL INITIATORS ARE DEFERRED)
- QUANTITY RESULTS OF EXAMINATION FOR THE SEQUENCES THAT CONTRIBUTE TIIE MOST TO Tile TOTAL CORE DAMAGE OR LARGE RELEASE FREQUENCY
- UNDERSTAND WHAT COULD POSSIBLY GO NRONG IN A PLANT.
- IDENTITY AND EVALUATE MEANS FOR IMPROVING PLINT /
CONTAINMENT PERFORMANCE (VIA IIARDWARE ADDITIONS /
MODIFICATIONS, ADDITIONS TO PROCEDURES, TRAINING);
- DECIDE WillCll IMPROVEMENTS WILL BE IMPLEMENTED AND SCHEDULE FOR IMPLEMENTATION 4
IPE BENEFITS o PIANT-SPECIFIC PRA's YIELDED INSIGHTS TO UNIQUE SEVERE ACCIDENT VULNERABIIlTIES LEADING TO IAW-C057 MODIFICATIONS o UTILITY INVOLVEMENT IN UNDERSTANDING POSSIBLE RANGE OF SEVERE ACCIDENT BEllAVIOR IN ITS PIANT(s) AND THUS IS BLTI'ER PREPARED TO PREVENT, AND/0R MITIGATE ACCIDENT PROGRESSION AND CONSEQUENCES o INCORPORATE THE PIANT SPECIFIC INSIGHTS (e.g., RECOGNITION OF ROLE OF PREVENTION AND MITIGATION SYSTEMS AND OPERATOR ACTIONS) AND IMPROVEMENTS (e.g., IIARDWARE, PROCEDURES)
RESULTING FROM THE IPE INTO A SEVERE ACCIDENT MANAGEMENT PROGRAM i
i 5
- 3. EXTERNAL EVEhTS o
COMMISSION SEVERE ACCIDENT POLICY DOES NOT EXCLUDE EXTERNAL EVENTS.
LICENSEES ARE ONLY REQUESTED TO PROCEED WITH THE o
EXAMINATIONS FOR INTERNAL EVENTS STAFF IS WORKING WITH NUMARC FOR DEVELOPMEliT OF o
ACCEPTABLE METHODOLOGY o
QUESTION IS HOW TO DEST HANDLE EXTERNAL EVENTS IN SEVERE ACCIDENT POLICY IMPLEMENTATION STAFF CURRENTLY EXAMINING EXTENT TO WHICII EXTERNAL EVENTS MUST BE TREATED WORK TO DATE INDICATES:
o SOME EXTERNAL EVENTS SHOULD BE LOOKED AT BY ALL PIANTS o SOME EXTERNAL EVENTS ARE UNIQUE ONLY TO A FEW PLANTS o SOME EXTERNAL EVENTS MAY BE ACCEPTABLY TREATED BY EXISTING DESIGN BASIS.
o Tile STAFT INTENDS TO EFFECTIVELY INTEGRATE ALL ONG0ING PROGRAMS DEALING WITil EXTERNAL EVENTS (e.g., A-46 SDMP)
SO NO DUPLICATION OF EFFORT BY INDUSTRY WILL OCCUR 0
I
EXTERNAL EVENTS (' CONT.)
EXTERNAL EVENT ISSUE o MANY POSSIBl.E SOURCIS OF HAZARD l
o CHANCING CRITERIA (P! ANTS NOT UNIFORMLY DESIGNED) o LUr! UNCERTAINITIES IN ESTIMATING FREQUENCY OP PARE EVENTS o NEED TO DETERMINE PROPER MIX OF PROBABlllSilC AND DETERMINISTIC APPROACH FOR VARIOUS llA2ARDS NO PARAfD't OVERAIL INDUSTRY EFFORTS (i.e., SIMIIAR TO o
THAT FOR INTERNAL EVENTS) YET IN PIACE e
l
EXTERXAL EVEXTS 'C0XT.}
STEERING GROUP MISS"0X o
REC 010END H0Y BEST TO TREAT EXTERNAL EVENTS IN CONTEXT OF THE SEVERE ACCIDENT POLICY o
ENSURE THAT RECOMMENDED TREATMENT IS COORDINATED WITH OTHER AGENCY PROGRAMS RELATED TO EXTERNAL EVENTS AND NO DUPLICATION OF EFFORTS RESULTS o
COMPLETE TASK IN APPR0XIMATELY 18 MONTHS l
I 8
- 4. METHODS OF AXALYSIS o THE GENERIC Irrn1K SPECIFIES SEVERAL OPTIONS THAT COULD BE USED f0 SATISFY THE EYAMINATION REQUIREMENTS IDCOR IPEMs FRONT END WITH STAFF ENHANCEMENTS +
CONTAINMENT PERFORMANCE ANALYSIS CONSISTENT WITH APPENDIX 1 LEVEL-I PRA + CONTAINMENT PERFORMANCE ANALYSIS CONSISTENT WITH APPENDIX I ( OR LEVEL-H OR -III PRA WITH "BACK-END" CONSISTENT WITH APPENDIX 1)
OTHER SYSTEMATIC EVALUATION METHODS (STAFF PREVIET MIGHT BE NECESSARY) 1 i
I l
9 1
i
IDCOR METHOD FRONT END 0
PiCOR (P2Ms COVER SOUENCES INITIATED BY INTERNAL EVENTS, IDSS OF OFFSITE P0YER AND INTERNAL FLOODS.
O IDCt2 d*Ws INYOLY5 TIIE NLLOWING BASIC ELEMENTS OF LEVEL-; h a
- PIAN't FArJARTIATION AND SYSTEMS N01EB00KS INCLUDES SUBSTANTIAL AWOUNT OF DESIGN, OPERATIONAL.
l AND PRA INFORMATION (SCHEMATICS, INTERFACES, DATA, CIIT-SETS (PWR IPEM ONLY))
- ACCIDENT SEQUENCE DEFINITION AND QUANTIFICATION RECOGNIZES TIIE IMPORTANT ROLE PLiYED BY SUPPORT SYSTEMS. INTERDEPENDENCE AMONG SUPPORT SYSTEMS IS ANALY2ED T0 (DENTIFY A SET OF SUPPORT STATE.
DATA ASSESSMENT AND PARAMETER ES'I1MATION INVOLVES INVESTlGATION OF DATA APPUCABIUTY, AND i
ANALYSIS OF PLANT SPECIFIC EXPERIENCE (FAILURE I
RATES AND INITIATOR FREQUENCIES)
INTERPRETATION OF THE RESULTS 10
IDCOR IPEMs EVALUATION THE IDCOR IPEMs TAKE ADVANTAGE OF AVAIIABLE IDCOR REFER o
PLANT ANALYSES, SIMILARITIES AMONG PLANTS AND UP-T0-DATE KNOWLEDGE OF SEVERE ACCIDENT PIIEN0MENA. THE IPEMs SYS ANALYSIS IS LESS RIG 0ROUS THAN A FULL SCOPE PRA.
THE IDCOR IPEMs WERE SUBMITTED TO THE NRC MAY 1986 o
INITIALLY MODIFIED BY IDCOR IN DECEMBER 1986 TO o
ACCOMODATE NRC COMMENTS. FURTIIER MODIFICATIONS WERE RECEIVED IN APRIL 1987 NRC EVALUATION OF THE IDCOR IPEMs IS COMPLETE o
IT IS EXPECTED THAT THE 1.EVEL OF EFFORT REQUIRED IF A o
UTILITY USES Tile IDCOR IPEM IS EQUIVALENT TO LEVEL-I PRA BUT IS LESS TIIAN IF A FULL-SCOPE LEVEL-III PRA WERE USED 11
IDCOR IPEMs EVALUATION { CONT.)
(FRONT-END) o KEY AREAS OF NRC CONCERNS:
- BMPHASIS ON BOT 10M IlNE NUMBERS, NAMELY CORE DAMA0E FREQUBNCY.
THE STAFF EMPEASIZES IDENTIFICATION OF PIANT SPECIFIC YUlNERADIUTIES, USTING OF POTENTIAL AREAS FOR IMPROVEMEN'IS AND SELECTION OF MOST PROMISING IMPROYEMENTS FOR IMPLEMENTATION
- NO TEST APPUCATION OF THE REVISED IPEMs
- ALMOST ALL TEST APPUCATIONS BAD THE BENEFIT OF A FUli SCOPE PRA WHICH IN THE STAFF'S OPINION COULD HAVE LWLUENCED THE lPE
- IDCOR BWR IPEM DOES NOT ASSURE A COMPLETE EVALUATION OF TIIE NET IMPACT OF SYSTEM DESIGN AND OPERATIONAL MODIFICATIONS ON THE OVERAll PLANT RISK ESTIMA7E
- EXTREME CARE NEEDED IN MODEUNG SUPPORT S7ATES. TIIE CRITERIA FOR DE7ERMINING WHEN HORE DETAILED ANALYSIS OF SUPPORT STATES IS NEEDED IS LDT TO Tile ANALYST o 5TAFF EVALUATION PROPOSES SEVERAL ENHANCEMENTS TO ADDRESS Tile ARfAS OF CONCERNS IN TI!E FRONT-END 12
IDCOR IPEMs EVALUATION (CONT.)
(BACK-END) o THE IDCOR BACK-END IPEMs ARE T00 NARROWLY FOCUSED AND WILL NOT PROVIDE UTILITIES WITIl INFORMATION NEEDED TO EXAMINE CONTAINMENT PERFORMANCE FOR THE FULL RANGE OF SEVERE ACCIDENTS o RELY VEF.Y HEAVILY ON IDCOR VIEWS OF SEVERE ACCIDENT PHENOMEN0 LOGY AND THE IDCOR MAAP CODE o SOME OF IDCOR VIEWS AND METil0DOLOGY ARE IN DISAGREEMENT YlTH CURRENT RANGE OF ASSUMPTIONS o NO RECOGNITION OF UNCERTAINITIES IN Tile PREN0 HEN 0 LOGY OPTIMISTIC ASSESSMENT OF CORRECT OPERATOR ALT 10NS TO MAINTAIN o
CONTAINMENT INTEGRITY DURING SEVERE ACCIDENTS o LOOSE INTERPRETATION OF Tile IPEM QUESTIONS DY TIIE UTIllTIES COULD RESULT IN A LICK 0F SUFFICIENT ATTENTION TO MEASURES TO MITIGATE Tile CONSEQUENCES OF AN ACCIDENT o APPENDIX 1 TO TIIE GENERIC LETTER PROVIDES ADDITIONAL GUIDANCE ON liOW TO ASSESS Tile CONTAINMENT PERFORMANCE 13
SCOPE /0BJECTIVES-STAFF GUIDANCE
'BACK-END) o THE IPE SHOUID PROVIDE BASIS FOR UTILITY'S
- APPRECIATION OF SEVERE ACCIDENT BEHAVIOR RECOGNITION OF ROLE OF MITlGATION SYSTEMS
- DEVElhPMENT OF ACCIDENT MANAGEMENT PROCEDURES THE IPE SHOULD PROVIDE A REAUSTIC EVALUATION OF CONTAINMENT o
PERFORMANCE IIENCE STAFF GUlDANCE FOCUSES ON IIAVING UTluTIES:
.n EVALUATE CONTAINMENT FAILURE MECHANISMS AND TIMING SIMPLY LOOK UP RELEASES FROM TABLES PREPARED ON Tile BASIS OF REFERENCE PL\\NT EVALUATIONS INTEGRATE SYSTEMS RESPONSE (PROBADILISTICALLY) INTO SIMPUFIED,BUT REAUSTIC, CONTAINMENT EVENT TREES (A110W FOR REC 0VERY OR OTHER ACCIDENT MANAGEMENT PROCEDURES)
- EXAMINE ALL CL\\SSES OF SEQUENCES WITil SIGNIFICANT PROBABluTY
- RECOGNIZE AND AS APP 110PRIATE, ACCOUNT FOR UNCERTAINITIES 14
- 5. REIATIONSHIP TO USI A-45 o A-45 ANALYSES IIAVE S110TN THAT DECAY HEAT REMOYAL FUNCTION FAILURE ARE SUFFICIENTLY PLANT SPECITIC AND NOULD REQU1RE SYSTEMnTIC EXAMINATION o PROPOSED STAFF RESOLUTION OF A-45 IS TO SUBSUME ISSUE INTO IPEs o TIIE PROPOSED GENERIC LETTER STATES TilAT THE IPE SIIOULD IDENTIFY THE VULNERABLE ASPEC*S OP DlIR FUNCTION o Tile PROPOSED GENERIC LETTER PROYlDES INSIGHTS GAINED FROM SIX LIMITED SCOPE PRA PERFORMED BY NRC UNDER THE A-45 PROGRAM i
I 15
- 6. BENEFITS OF PRA o OTHER USIs AND GSIs IF IPE IDENTIFIES RESIDUAL VULNERABIUTY THAT IS TYPICALLY ASSOCIATED YlTH USl OR GS1 AND (TITUTY PROPOSES A MEASURE ACCEPTABIE TO 111E STA!7 TO EUMINATE OR TO SUBSTANTIALLY REDUCE THE VUIRERABIUTY, THE USI OR GSI MAY BE CONSIDERED CLOSED ON A A PIANT SPECIFIC BASIS o UCENSE RENEWALS PRA COUID BE USED TO IDENTITY RISK-SIGNIFICANT COMPONENTS AND SYSTEMS FOR YIUCII AGE-RBIATED DEGRADATION CONCERN MUST BE ADDRESSED DURING THE UCENSB RENEWAL PERIOD o PETS RISK WANAGEMENT PROGRAM THAT CONTINUALLY ASSESSES THE SAFETY OF THE PIANT PROVIDES A POWERFUL TOOL TO 11IE PIANT MANAGEMENT o SUPPORT FOR UCENSING ACTI0t'-
PRA MIGHT BE USED TO JUST1FY TECIINICAL SPECIFICATION CILANGES o INTEGRATED SAFETY ASSESSEMENT PROGRAW II 0fTfMlZES TllE B)TAL SAFETY AND EXPEDITES SCllEDUlf TO IMPLEMENT FIXES 16
c
- 7. SEVERE ACCIDENT SEQUENCE SELECTION (SCREENING CRITERIA) o USED TO DETERMINE TIIE POTENTIALLY IMPORTANT FUNCTIONAL SEQUENCES WIUCD REQUIRE CONTAINMENT EVENT TREE ANALYSIS. NOT TO DE7 ERMINE IT PLANT IMPROVEMENTS ARE REQUIRED o INCLUDE SEQUENCES YHICH CONTRIBUlE MORE THAN 5% TO TIIE PREDICTED CORE DAMAGE PREQUENCY INCLUDE SEQUENCES FOR WIIICH TIIB CORE DAMAGE FREQUENCY
.o IS GREATER TBAN 1E-6/ REACTOR YEAR o INCLUDE SEQUENCES USEFUL FOR IDENTITYLNG SYSTEMS WEAKNESS OR OPERATOR ACTIONS BASED ON DETERMINISTIC EVALUATIONS, ENGINEERING JUDGEMENT AND CONSIDERATION OF UNCERTAINITIES IN TIIE PROBABlIJSTIC ANALYSIS INCLUDE SEQUENCES FOR WHICH THE CDF IS GREATER THAN lE-8/
o REACTOR YEAR AND CONTAINMENTS PAIIS IN LESS TilAN 12 HOURS FR0X TIME OF YESSEL PENETRAT!DN o INCLUDE SEQUENCES THICH LEAD TO CONTAINMENT BYPASS AND llAVE A PRODABil1TY OF OCCURRENCE GREATER TilAN lE-7/RXY U
- 8. ROLE OF SEVERE ACCIDENT MANAGEMENT SEVERE ACCIDENT MANAGEMENT IS A FR0 CESS IN WHICII ACTIONS THAT o
CAN PREVENT CORE DAMAGE OR MITIGATE THE CONSEQUENCES OF SEVERE ACCIDENT ARE IDENIIFIED, EVALUATED, INCORPORATED INTO A SITlUCTURED PROGRAM, [MPLEMENIED AT A PIANT SriE AND ARE AVAllABLE TO THE OPERATORS AND PLANT MANAGEMENT IN TIIE EVENT OF SDIRE ACCIDENT o SEVERE ACCIDEAT MANAGEMENT ENCOMPASSES IIARDWARE, IIUMAN, AND ORGAh%lAT10NAL FACTORS IT PROVIDES DECISION MAKERS AT TIIE PLANT A STRUCTURED o
PROGRAll FOR MANAGING A SEVERE ACCIDENT PROPOSED GENERIC [flTER ADDRESSES SDIRE ACCIDENT o
MANAGEMENT AS F011DNS
- UTillTIES ARE EXTECTED TO DDILOP AN ACCIDBST MANAGEMENT PROGRAM FOR PREVENTION OR MITIGATION OF RISK IMPORTAhT SEVERE ACCIDENTS
- IDEhTIFY MEASUPIS TIIAT PIANT PERSONNEL CAN AND SHOULD TAKE IN CASE OF SEVERE ACCIDENT. ASSESS AGAINST Tile CRITERIA 0F 10 CFR 50,50 AND, IF APPROPRIATE, SUDM11T TOR NRC RD'IEW IN ACCORDANCE WITIl 10 CTR 50.00
- UTillTIES SliOULD PREPARE TO SUCCESSFUL 1Y EXCUTE MEASURES TilAT WEP.E FOUND T0 (1) PRDIST CORE DAMAGE, (2) PRDINT CORE DEDRIS FROM l
PENLTRATING Tile VESSEL OR, (3) MANAGE Tile C0 SEQUENCES STAFF AND NUMARC DISCUSSING DEST WAY TO DD'ELOP AND IMPLIMENT o
SUCll PLAN 18
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- 9. SEVERE ACCIDENT PREVENTION AND MITIGATION FEATURE REPORTS (NUREG/CR-4920) o THE KNOWEDGE AND INSIGHTS GAINED FROM THE REVIEW AND ANALYSIS PERFORWED BY IDUSTRY AND NRC WERE COUSCTED TOGETHER, AND SORTED ACCORDING TO APPUCABiUTY TO RFACTOR TYPES IIlGIIUGHT (NOT TO SPECIFY) PIRT TEATURES AND OPERATOR o
ACTIONS THAT TERE FOUND TO BE IMPORTANT TO RISE IN PREVIOUS STUDIES o PLANT FEATURES AND OPERATOR ACTIONS
- AVAILABIUTY OF SUPPORT SYSTEMS AND IDENTIFICATION OF NECESSARY COMPONENTS
- IDENTIFICATION OF IMPORTANT OPERATOR ACTIONS IDENTIFICATION OF PARAMETER FOR INITIATION OF MITIGATING SYSTEMS AND OPERATOR ACTIONS
- SURVIVABIUTY OF EQUIPMEh7 i
- EQUIPMENT CAPAElu11ES, CAPACITIES, AND DURATION OF 0FFFABIUTY
- ACCESSIBIUTY OF EQUlPMENT NUREG/CR-4020 SUMMARIZlNG PAST EXPERIENCE HAVE BEEN o
PROVIDED TO CRGR 19
- 10. DOCUMENTAION OF IPE RESULTS o PROVIDE THE BASES FOR THE FINDINGS IN A TRACABLE MANNER o TY0 TIERS OF DOCUMENTATIONS o TIER-1 REPORTS THE RESULTS OF THE EXAMINATION TO NRC
- THE LEADING SEQUENCES AND SCREENING CRITERIA
- THE CORE DAMAGE FREQUENCY AND THE LIKTIJH00D OF LARGE RELEASE
- Tile MAIN CONTRIBUTORS FOR CDF AND CONTAINMENT FAILURE
- DISPOSTION OF CONTRIBUTORS o TIER-2 DOCUMENTS THE EXAMINATION THAT WOULD BE RETAINED BY LICENSEES o
NRC YlLL EVALUATE TIER-1 REPORTS AND MAY AUDIT TIER-2 20
IPE RESULTS REVIEW o PREPARE AN IPE REmW DOCUMENT FOR THE STAFF AND 00NTRALTOR REVIEWERS TO INCLUDE:
- AREAS OF REVIEW
- DLTERMINATION OF ADEQUACY OF IPE RESULTS
- ALTION IRELS
- INTERPRiffATION OF THE RESULTS
- SAMPLE EVALUATIONS 4
1 o
IPE REVIEW DOCUMENT WILL BE MADE AVAILABLE TO ALL I
UTILITIES SHORTLY AFTER THE ISSUANCE OF THE GENERIC IEITER l
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IPE RESULTS REVIEW (CONT.)
o THERE ARE 109 UCENSED PLANTS, REPUCATE PLANT WOULD REDUCE THE IPE SUBMllTAIS TO 80 o 6 PERSON-MONTH PER PIANT REVIEW 0F THE IPE SUBMITTAIS INCLUDING REVIEW 0F ANY PROPOSED MODIFICATION o IPE SUBMllTAIS ARE ESTIMATED TO BE OVER A PERIOD OF 31 EARS o STAFF COMPIETE REVIEW WITHIN 5 YEARS 4
o APPR0XlMATELY 8 PERSON-YEARS EFFORT PER YEAR FOR 5 YEARS o APPR0XlMATELY $1.4M PER YEAR ( 8 STAFF YEARS) ; $7M OVER 5 YEARS o IN CASE OF DISAGREEMENT, THE STAFF WIII PURSUE FIX IN ACCORDANCE WITH TBE BACKFIT RULE OR ORDER o TEAM CONCEPT-EACH PIANT REYlEW TO DE TIIE RESPONSIBlMTY ONE NRC TEAM LEADER, SEVERAL PIANT SYSTEMS SPECIAUSTS, AND PRA SPECIAUST o TWO TEAMS WILL DO ONLY LARGE DRY, ONE TEAM VILL D0 MARK I & II AND ONE TEAM WIIL DO MARK III AND ICE CONDENSER 22
4 STAFF USE OF [PE RESULTS o REVIEW 0F IPE RESULTS FOR THE F0110NING:
- TO ENSURE ADEQUATE ANALYSIS OF PLANT DESIGN AND OPERATIONS TO DISCOVER PARTICUIAR VULNERABIUTY TO CORE DAMAGE AND UNUSUALLY POOR CONTAINMENT PERFORMANCE
- FOR CONSISTENCY IN THE IDENTIFICATION AND TREATMENT OF LEADING CORE DAMAGE SEQUENCES TO ENSURE SEQUENCES AND SEQUENCE FREQUENCIES ARE APPROPRIATE I
- T0 INDEPENDENTLY CONCLUDE THAT DECISIONS ON WHLTHER TO MAKE IMPROVEMENTS ARE JUSTIFIED i
- TO ALLOW COMMISSION TO CONCLUDE THAT THE SEVERE ACCIDENT POUCY HAS BEEN RESPONSIBLY IMPLEMEhTED BY INDUSTRY o CONSIDERATION WILL INCLUDE BOTH QUANTITATIVE MEASURES AND NON QUANTITATIVE JUDGMENT TO DETERMINE IF A PIANT IS ACCEPTADLE OR NOT o IF NRC COSIDERATION IDICATES THAT PLAhT DESIGN OR OPERATION COULD I
BE ENHANCED 1V DECREASE RISK TO LESS THAN ADEQUATE PROTECTION STANDARD, IMPLEWENTATION WOUU) BE IN ACCORDANCE WITH 10 CFR 50.109 l
o IF CONSIDERATION INDICATES ENHANCEMEhT NEEDED TO MEET AN ADEQUATE i
PROTECTION STANDARD, IMPLEMENTATION YOULD BE WITHOUT REGARD TO i
COST EICEPT TO SELECT AM0hG ALTERNATIVES o IPE RESUL13 V01 BE USED TO IDENTIFY SEVERE ACCIDENT YULNERABlUTY GENERIC TO CIASS OR SEVERAL CLASSES PLANTS
- TIDS INFORMATION ON GENERIC VULNERABIIJIIES WOULD BE USED TO EIAMINE IF DEFICIENCIES IN THE REGULATION EXIST IF GENERIC DEFICIENCIES WERE IDENTIFIED, SAFETY G0AL WOULD I
DE USED TO DETERVINE IF REGULATION MODIFICATIONS WERE hTEDED l
23 i
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