ML20235N549
| ML20235N549 | |
| Person / Time | |
|---|---|
| Issue date: | 06/11/1987 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-2505, NUDOCS 8707200126 | |
| Download: ML20235N549 (55) | |
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DATE ISSUED: 6/11/87
% r7 ACRS SUBCOMMITTEE MEETING
SUMMARY
/ MINUTES ,
FOR SEVERE ACCIDENTS l
MAY 28, 1987 WASHINGTON, D.C.
Purpose The ACRS Subcommittee on Severe Accidents met on May 28, 1987 in Wash-ington, DC. The purpose of this meeting was to discuss a proposed generic letter entitled, " Individual Plant Examinations for Severe Accident Vulnerabilities," which is part of the Staff's implementation plan for the Severe Accident Policy Statement. Copies of the agenda and selected slides from the presentations are attached. The meeting began ;
at 8:30 a.m., and adjourned at 3:25 p.m., and was held entirely in open session. The principal attendees were as follows:
Attendees ACRS NRC/RES W. Kerr, Chairman T. Speis P. Shewmon, Member F. Coffman l C. Siess, Member Z. Rosztoczy D. Ward, Member A. El-Bassioni M. Corradini, Consultant F. Eltawila P. Davis, Consultant T. Theofanous, Consultant J. Lee, Consultant T. Pratt, Consultant >
D. Houston, Staff IDCOR l T. Buhl (ITC)
R. Henry (Fauske)
J. Carter (ITC) l Discussion The Commission's Severe Accident Policy Statement sets forth the in- 4 tentions for rulemakings and other regulatory actions for resolving safety issues related to reactor 6ccidents more severe than design basis n ,cif;D CLIGIEAL
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I 2505 PDR ,
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o Severe Accidents Minutes May 28, 1987 accidents. The main focus is on the review and certification of new standard plant designs. It also provides guidance for resolution of issues for other classes of future plants and for existing plants. The nroposed generic letter addresses the search for vulnerabilities for existing plants.
In his opening statement, W. Kerr indicated that he thought some pro-gress had been made in what has been a rather chaotic situation. He expressed concerns about the lack of definition in the proposed generic letter and questioned whether a utility would know how to proceed and how to identify acceptable results. He further indicated that the letter did not put much emphasis on human error and that the examination j process should be in an easily traceable form.
l T. Speis made some introductory remarks about the proposed generic letter and discussed where it fits into the overall implementation plan I
for the Severe Accident Policy Statement. He indicated that the most important aspect of the IPEs would be the insights gained by the utility for application into accident management schemes. F. Coffman discussed the details of the proposed generic letter which included: information-l al package to be transmitted to each utility, scope of the IPE, consid-eration of external events, evaluation o"7 the IDCOR IPE Methodology, documentation of IPE results and schedule. A. El-Bassioni and F.
l Coffman discussed the Staff Evaluation of the IDCOR-IPEM, listing the l strengths and limitations for the front-end and back-end methodology.
The level-of-effort for a utility with no PRA experience was estimated by the Staff to be 4 to 7 man-years.
T. Buhl (ITC) reviewed the chronology and technical development of the IDCOR-IPEM. R. Henry (Fauske) presented a brief overview of the IPEM.
He indicated that plant personnel would gain insights from the assembly of the information for system notebooks and that plant vulnerabilities L
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Severe Accidents Minutes May 28, 1987 l
would be found by examination of the impact vector: analysis (BWRs) or !
system dependence matrix (PWRs).
I During the meeting, Subcommittee members and consultants expressed j concerns and opinions as follows:
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(1) W. Kerr expressed concerns in regard to the absence of written basis for Staff judgement for IPE results and questioned the Staff about guidance for containment performance and handling of j unresolved safety issues. )
l I (2) P. Shewmon and C. Siess questioned the definition of plant vul-nerabilities and indicated that the proposed generic letter may go beyond the objective as stated in the Policy Statement. C. Siess also questioned how generic matters would be considered in this review. Since generic items would be an outlier on all plants, the Staff did not intend to have each plant perform an individual analysis.
(3) D. Ward questioned how sabotage is addressed-in the Severe Accident Policy Statement and if it is considered in the IPE.
(4) M. Corradini expressed concerns about the capability of individual utilities to perform the IPE in-house and thus gain benefits from the insights developed. He suggested that the Staff select a few plants and cooperatively perform the IPE on those plants as an aid J to the Staff in the development of guidance, criteria, methodology and goals. l (5) P. Davis indicated that the generic letter should provide more guidance on what is acceptable for a PRA. He questioned the quantitative definition of vulnerability.
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' Severe Accidents Minutes May 28, 1987 (6) J. Lee emphasized that the maximum benefit of this study would be.
gained by the utility if it performed the study in-house. He suggested that the generic letter be written is such a way as to
-encourage the utility to do this analysis with a minimum of.outside assistance. He also requested that the generic letter provide more clarification in regard to accident management issues, perhaps in the guidelines and criteria.
Attachments: As Stated
- For More Information See Transcript ********
NOTE: Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room, 1717 H Street, N.W., Washington, D.C., or can be purchased from ACE-Federal Reporters, 444 North Capitol Street, Wash-ington, DC 20001, (202) 347-3700. '
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s' ACRS Severe Accidents Subcommittee Meeting May 28, 1987 Washington, DC
- Tentative Presentation Schedule - _
Proposed Generic Letter for Individual Plant Examinations (IPEs)
A. Subcommittee Chairman Remarks W. Kerr 8:30 am B. Introductory Remarks T. Speis. 8:40 am C. Proposed Generic Letter for F. Coffman 9:00 am Individual Plant Evaluations -
l- '(IPEs)
- Options
- Role of Guidelines and "
Criteria D. Scopa of the.IPE F. Coffman 9:40'am l *** Break *** 10:00 - 10:15 am j E. Staff Evaluation of IDCOR IPEM 10:15 am i Front-End A. El-Bassioni -
Back-End(SourceTerm) F. Coffman
- Lunch *** 11:30 - 12:30 pm F. Results and Schedules F. Coffman 12:30 pm
- Documentation
- Results
- Accident Management
- Schedules and Review Plan G. IDCOR Presentation J. Carter / 1:10 pm T. Buhl/R. Henry
- Break *** 2:10 - 2:25 pm
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H. Concluding Remarks / W. Kerr 2:25:pm' Subcommittee Discussion -
- Adjourn ***
3:30 pm
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1 1 RES STAFF PRESENTATION TO THE ACRS i
SUBJECT:
INITIATION OF TE SE\ERE ACCIENT POLICY STATFJENT INDIVIDUAL PLANT EXAMINATION ,
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! DATE: FAY 28,1937
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1 PRESENTER: TEMIS SWIS
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PRESENTER'S TITLE / BRANCH /DIV: EPlfiY DIRECTOR !
l FOR EERIC AND REGLLATCRY ISSLES l I
0FFICE OF NUCLEAR REGilATORY RESEARCH l
PRESENTER'S NRC TsL. NO.: (301)f492-7517 l'
SUBCOMMITTEE: CLASS 9 ACCIENT e
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e TOPICS FOR DISCUSSION
. o GENERIC LETTER TO INITIATE THE IPEs x.
o SCOPE OF IPEs l
l 0 EVALUATION OF IDCOR IPE METHODS ,
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l c IPE RESULTS DOCUMENTATION AND SCHEDULE c IDOCR PRESENTATION I
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GOALS AND OBJECTIVES OF IPE ,
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l TO IDENTIFY PLANT-SPECIFIC VULNERABILITIES TO SEVERE ,
i L ACCIDEN1S (FOR BOTH CORE DAMAGE AND CON 1AINMENT PERFORMANCE),
I IDENTIFY AND EVA.LUATE MEANS FOR IMPROVING PLANT / CONTAINMENT ,
PERFORMANCE TO COPE WITH THESE PLANT-SPECIFIC VULNERABILITIES, l IMPLEMENT CORRECTIVE ACTIONS / IMPROVEMENTS; INCORPORATE KNOWLEDGE AND INSIGHTS INTO ACCIDENT MANAGEMENT SCHEME (OPERATING PROCEDURES, TRAINING PROGRAMS, ETC.), l b -
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IPE ISSUES QUESTIONS ABOUT COMPLETENESS OF PLANT ANALYSES DUE TO LARGE UNCERTAl!! TIES ASS 0fl ATED WITH SOME GENERIC ISSL'ES GENERIC ISSUES, SUCH AS FOR EXAMPLE THE POTENTIAL FOR EARLY CONTAIWENT FAILURE VIA DIRECT CONTAINMENT HEATING (INCLUDING SGT FAILURE AND CONTAINMENT BY-PASS), AND. j l 1 9
UNC0FTROLLED HYDROGEN BURNING NEED FURTHER EVALUATIONS (DESIGN FIXES AND/OR FURTHER RESEARCH AND ANALYSIS),
l e HOWEVER, THERE ARE SAFETY BENEFITS TO BE OBTAINED BY -
l PROCEEDING WITH THE IPEs AND THE DEVELOPMENT OF i
PLANT-SPECIFIC IMPROVEMENTS AND APPROPP.IATE SEVERE ACCIDENT MANAGEMENT PLANNING.
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IPE'BENEFIIS s
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UTILITY INVOLVEMENT IN-UNDERSTANDING POSSIBLE RANGE OF - -
1 SEVERE ACCIDENT BEHAVIOR IN.ITS PLANT (S) AND THUS BETTER PREPARED TO PREVENT, AND/OR MITIGATE THEIR PROGRESSION AND !
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CONSEQUENCES.
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INCORPORATE THE PLANT SPECIFIC INSIGHTS (E.'G., RECOGNITION I
'i UF ROLE OF PREVENTION AND MITIGATION SYSTEMS AND OPERATOR-ACT10f!S) AND IMPROVEMENTS (E.G., HARDWARE, PROCEDURES).
RESULTING FROM THE IPE INTO A SEVERE ACCIDENT MANAGEMENT PROGRAM.
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PACKAGE TO UTILITY -
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l RES WILL PREPARE THE PACKAGES FOR NRR TO ISSUE TO ALL UTILITIES RE0t!ESTING INDIVIDUAL PLANT EXAMINATIONS (IPE) FOR SEVERE ACCIPENT VULNERABILITIES IN ACCORDANCE WITH THE SEVERE ACCIDENT POLICY STATEMENT. EACH PACKAGE WILL CONTAIN:
O o GENERIC LETTER o Gl!IDELINES AND CRITERI A EY PLANT TYPE o APPLICABLE IDCOR IPEM EVALUATION c REFERENCE LIST
- NUREG-3150, NUREG/CR-4550, NUREG/CR-4551, NUREG/CR-4700, NUREG/CR-4624 IDCOR PROGRAM TECHNICAL REPORTS
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GENERIC LETTER- l l
1 a 1NITIATE THE IPE c '
PHASE I
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,. IDENTIFY POTENTIAL SEVERE ACCIDENT. SEQUENCES ~
DETERMINE THE LEADING CONTRIBUTORS j
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IDENTIFY POTENTIAL AREA 0F IMPROVEMENTS 'l ESTAPlISH ACCIDENT MANAGEMENT SCHEMES PHASE 2 l
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IDENTIFY AN IMPLEMENTATION SCHEDULE FOR PLANT SPECIFIC CORRECTIVE ACTION (S), INCLUDING ACCIDENT MANAGEMENT PLANNING l
o THE GENERIC LETTER SPECIFIES 5 OPTIONS THAT COULD BE USED TO SATISFY THE EXAMINATION REQUIREMENTS IDCOR IPEM LEVEL II OR Ill PRA LEVEL I PRA SUPPLEMENTED PITH CONTAINMENT ANALYSIS SIMPLIFIED PRA WITH APPROVAL -
OTHER SYSTEMATIC EVALUATION METHODS WITH APPROVAL 10 .
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UTILIZATION OF PAST EXPERIENCE AND INSIGHTS
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(GUIDELINES AND CRITERIA) e c GUIDELINES IDENTIFY TPOSE PLANT FEATURES AND OPERATOR ACTIONS'
! THAT WERE FOUND TO BE IMPORTANT TO RISK IN PREVIOUS STUDIES, o IT IS INTENDED TO HIGHLIGHT (NOT TO SPECIFY) POTENTIAL AREA ]
O 0F IMPROVEMENTS IN VARIOUS AREAS OF PLANT DESIGN AND OPERATION TO UTILITIES PERFORMING IPE,
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o CRITERIA ARE THE STANDARDS OR ATTRIBUTES CONSIDERED APPROPRIATE FOR ASSESSING THE PERFORMANCE OF SPECIFIC INDIVIDUAL PLAFT FEATURES OR OPERATOR ACTIONS IDENTIFIED IN THE GUIDELINES.
c THE CRITERIA ADDRESS: ,
SURVIVABILITY OF EQUIPMENT ,
- EQUIPMENT CAPABILITIES, CAPACITIES, AND DURATION OF 1 OPERABILITY f ACCESSIBILITY OF EQUIPMENT l
AVAILABILITY OF SUPPORT SYSTE'MS AND IDENTIFICATION OF NECESSARY COMPONENTS.
IDENTIFICATION OF IMPORTANT OPERATOR ACTIONS IDENTIFICATION OF PARAMETER FOR INITIATION OF MITIGATING SYSTEMS AND OPERATOR ACTIONS ~
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o OVER 20 PRAs HAVE BEEN PERFORMED FOR U.S. PLANTS. NRC AND i NPC CONTRACTORS REVIEWED APPROXIMATELY 10 PRAs, .
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e o PLEG ALONE PERFORMED APPROXIMATELY 20 PRAs. THE EXPERIENCE .
AND INSIGHTS GAINED FROM THIS FORK WAS SUMMARIZED BY PLEG FOR THE NRC AND NRC CONTRACTORS THROUGH DISCUSSIONS AND IN A 2 DAY SEMINAR.
o IDCOR ANALYZED FOUP REFERENCE PLANTS DOCUMENTED AND SUBMITTED THE ANALYSES TO NRC. ,
O o NFC ANALYZED FIVE REFEREUCE PLANTS (NUREG-1150); TFE DETAILED ANALYSES ARE DOCUMENTED IN 20 CONTRACTOR REPORTS, o THE KNOWLEDGE AND INSIGHTS GAINED FROM THE REVIEW AND ANALYSES MENTIONED AE0VE WERE COLLECTED TOGETHER, SOPTED ACCORDING TO APPLICABILITY TO REACTOR TYPES AND TRANSFORMED INTO GUlDELINES AND CRITERIA FOR THE INDIVIDUAL PLANT EXAMINATIONS (IPE),
i e FIVE SETS OF GUI-DELINES AND CRITERI'A REPRESENTING DIFFERENT CONTAINMENT TYPES WERE CIRCULATED FOR COMMENTS. THE LAST SET l OF COMMENTS WERE RECEIVED MARCH 1, 1987.
A REVIEW MEETING WITH REPRESENTATIVES FROM SANDIA, ORNL, BCL o
ANP PNL WAS HELD ON FEBRUARY 25, 1987.
c REVISED, FINAL' GUIDELINES AND CRITERIA ARE AVAILABLE FOR CRGR AND ACRS REVIEW.
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SCOPE OF IPE O PURPOSE 1 1
- UNDERSTAND WHAT COULD POSSIPLY G0 WRONG IN A PLANT, BE PPEPARED TO HANDLE THESE EVENTS (VIA HARDWARE ADDITION /V0 DEIFICATIONS, ADD TO PROCEDURES, TRAINING). . .
1 o EXAMINATION PROCESS ,
- A THOROUGH, SYSTEMATIC EXAMINATION OF PLANT DESIGN,
- OPERATIOf,11AINTENANCE AND EMERGENCY OPERATION.
IDENTIFICATION OF DOMINANT SEVERE ACCIDENT SEQUENCES FOR THE PLANT,
- IDENTIFICATION OF MAIN CONTRIBUTORS (HAPDWARE, PROCEDURES, TRAINING, MAINTENANCE) TO CORE DAMAGE.
FREQUENCY AND TO CONTAINMENT PERFORMANCE.
- COMPARISON WITH APPLICABLE GUIDELINES AND CRITERIA,.
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IDENTIFICATION OF DESIRAPLE PLANT ATTRIBUTES AND j ACCIDENT MANAGEMENT MEASURES.
' IDENTIFICATION OF POTENTIAL IMPROVEMENTS WITH RESPECT TO ACCIDENT PREVENTION AND ACCIDENT MITIGATION,
- EVALUATION OF POTENTIAL IMPROVEMENTS, DOCUMENTATION OF THE EVALUATION. DECISION CRITERIA: LICENSEE'S JUDGEMENT, PACKFIT RULE, J PROPOSE IMPROVEMENTS FOR THE PLANT. PROVIDE l JUSTIFICATION FOR IMPROVEMENTS NOT RECOMMENDED, 4
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e CONSIDERATION OF EXTERNAL HAZARDS ~IN IPE_E .;
1 c BOTH IDCOP AND NRC WORK HAS BEEN FOCUSED ON INTERNAL HAZARDS. . .
e o EXTERNAL HAZARDS NEED TO BE CONSIDERED.
o SCHEDULE FOR EXTERNAL HAZAPDS CAN FOLLOW AFTER THE INTERNAL HAZARDS IPEs. .
O PROGRAM STEPS:
- 1. DEFINE THE EXTENT TO WHICH PLANTS WERE REVIEWED FDR.
EXTERNAL HAZARDS.
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- 2. USE THE SSMR AND SDMR PROGRAM METHODS TO ESTIMATE MARGINS AGAINST EXTERNAL HAZARD THAT PAST REVIEWS PROVIDED. j l
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- 3. IDENTIFY SELECTED PLANT FEATURES THAT SHOULD BE EXAMINED EY A SEPARATE IPE FOR EXTERNAL HAZARDS, IF ANY.
- 4. PROVIDE GUIDANCE FOR THE EXAMINATION BY A SEPARATE IPE j FOR SELECTED EXTEPNAL HAZARDS. _
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IDCOR IPEM EVALUATION '
1 0 THE'ID.COR IPEM' TAKES AI' VANTAGE OF AVAILABLE IDCOR ': :
l REFERENCE PLANT ANALYSES, SIMILARITIES AMONG PLANTS AND-UP-TO-DATE KNOWLEDGE OF SEVERE ACCIDENT PHEF0MENA. THE IPE.
1 FLANT ANALYSIS IS LESS RIG 0ROUS THAN A FULL SCOPE PRA. ,
e o THE IPEM WAS SUBMITTED TO NRC MAY 1986 o IPEM WAS INITIALLY MODIFIED BY IDCOR IN DECEMBER 1986 TO ;
( ACCOMMODATE NRC COMMENTS. FURTHEP MODIFICATIONS WERE RECEIVED IN APRIL 1987.
o NRC EVALUATION OF THE IPEM IS COMPLETE. DOCUMENTATION WILL BE FINALIZED UPON RECEIPT OF SOME ADDITIONAL CONSULTANTS COMMENTS, FROM THE ACRS, CRGR, ETC. 2 I
o IT IS EXPECTED THAT 4 TO 5 STAFF-YEAP.S WOULD BE REQUIRED IF A l UTILITY USES THE IDCOR IPEM, VS. 15-20 STAFF YEARS IF A FULL-SCOPED, LEVEL II PRA WERE UTILIZED.
O REMAINING AREAS OF NRC CONCERNS:
- EMPHASIS ON BOTTOM NUMBERS, NAMELY CORE-DAMAGE FREQUENCY
' AND RISK; THE STAFF EMPHASIZES THE IDENTIFICATION OF PLANT SPECIFIC VULNERABILITIES, LIST OF POTENTIAL IMPROVE- _
MENTS AND SELECTION OF MOST PROMISING IMPROVEMENTS FOR IMPLEMENTATION. ,
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- NO TEST APPLICATION OF.THE REVISED ~ METHODS' O
THE BWR CONTAINMENT METHODOLOGY REMAIN UNTESTED. SINCE ]
NONE OF THE BWR TEST APPLICAT,10NS PROVIDED SOURCE TERM ASSESSMENT, HELD UP PENDING STAFF DISPOSITION OF BWP CONTAINMENT IN!TIATIVES, ALMOST ALL TEST APPLICATIONS HAD THE BENEFIT OF A FULL SCOPE PRA WHICH IN THE STAFF'S OPINION COULD.HAVE j
INFLUENCED THE IPE EXAMINATION.
SOME " GENERIC" ISSUES AFFECTING CONTAINMENT PERFORMANCE I
EVALUATIONS,
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- UTILITY'S ACTION, WHEN A SCREENING CRITERION IS NOT MET ARE NOT CLEAR.
I USE OF MAAP CODE l
0 STAFF EVALUATION PROPOSES SEVERAL ENHANCEMENTS TO ADDRESS-THE AREAS OF CONCERN,
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l IPEM FRONT EMP J v
SCOPE AND OBJECTIVES _
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IPEMs COVER SEQUENCES INITIATED BY INTERNAL EVENTS, LOOP AND'
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INTERNAL FLOODS.
OBJECTIVES AS STATED BY IDCOR:
l l .1 . ESTABLISH A REALISTIC CORE DAMAGE FREQUENCY ESTIMATE
- 2. IDENTIFY POTENTIAL ACCIDENT SEQUENCE OUTLIERS
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- 3. ACCOMMODATE REVISIONS AND UPDATES WHEN ADDITIONAL INFORMATION j PECOMES AVAILABLE.
- 4. BE SCPUTABLE AND USABLE WITHIN UTILITY MANAGEPENT 4
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I IDCOR IPEM GENERAL DESCRIPTIONS o PWR AND.BWR'IPEM INVOLVE ALL 0F THE BASIC ELEMENTS OF !
LEVEL-1 PRA:
PLANT FAMILIARI7ATION ACCIDENT SEQUENCE DEFINITION DATA ASSESSMENT AND PARAMETEP. ESTIMATION ACCIDENT SEQUENCE CUANTIFICATION AND, 9
INTERPRETATION OF THE RESULTS
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IDOCR IPEM GENERAL STRENGTHS-o DIRECT USE OF PRA EXPERIENCE -
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o NPPs TREATED ON UNIFORM AND CONSISTENT BAEIS
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I o USES A SMALL FRACTION OF THE RESOURCES REQUIRED FOR TYPICAL FULL-SCOPE PRA STUDIES l o A GOOD TOOL OR TECHNOLOGY TRANSFER TO UTILITIES WITH LIMITED I
OR NON-EXISTING PRA EXPERIENCE (UTILITY PARTICIPATION IS EMPHASIZED)
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IDCOR IPEM LIMITATIONS o INVESTIGATES THOSE FEATURES IDENTIFIED AS OUTLIERS IN PREV 10llS PRA STUDIES.
1.E., IPEM GUIDANCE AND DEPTH CF ANALYSES f1AY NOT BE SUFFICIENT TO IDENTIFY ALL OUTLIEP FEATURES UN10llE TO THE NPP.
F c FOTENTIAL'FOR EXTENSION (FRONT END) TO LEVEL-1 FRA EXIST.
SOME RISK MANAGEMENT DECTSIONS MAY REGUIRE ADDING DETAILS TO THE MODELS. ,
1 o IDOCR IPEMs RELY HEAVILY ON JUDGEMENT (CHOICE OF TEMPLATES, ADJUSTMENT FACTOR /N0DAL OUEST10NS). HIGH LEVEL OF.PRA EXPERTISE NEEDED TO REDUCE VARIABILITY.-
o IDCOR IPEM COULD BENEFIT FROM A COMMON UP-TO-DATE GEFEF.lC DATA EASE.
o LIMIkEDVERIFICATIONOFIDCORIPEMINDEPENDENTOFEXISTING PRA STUDIES.
o IT IS VERY HARD TO ESTABLISH EQUIVALENCE BETWEEN Pk'R AND BWR 1PEMS.
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o LESSONS LEARNED ABOUT THE' MANAGEMENT OF. PREVIOUS PRA STUDIE AND TECHNICAL AUDITS COULD HAVE BEEN USED TO FURTHER ENHANCE i
THE EFFICIENCY OF THE IDCOR IPE PERFORMANCE.
I o IDOCR IPEMs DO NOT INVOLVE UNCERTAINTY ANALYSIS (LIMITED .
SENSITIVITY ANALYSIS IS USED AS AN ALTERNATIVE)
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2 IDCOR-IPEM (BACK-END) ,
. PWR SOURCE TERM ANALYSIS 4
CBJECTIVE ENVELOPE F.P. RELEASES AND COMPAPE T0 IDCOR.
i REFERENCE PLANT, a FOCUS STATION BLACK 0UT AND APPROXIMATE RELEASE ]
CALCULATIONS, -
OTHER DETAILED ANALYSIS FOR ISOLATION FAILURE OF BYPASS SE0VENCES AS' REQUIRED BY PROBABILITY, STAFF RESERVATIONS c SCOPE /0BJECTIVES o OUTSTANDING GENERIC ISSUES .
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e CONTAINMENT SYSTEMS INTEGRATION WITH PHENOMENA I
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p SCOPE /0BJECTIVES-STAFF GUIDAllCE ]
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o THE IPEM SHOULD PROVIDE BASIS FOR UTILITY'S APPRECIATION OF SEVERE ACCI. DENT BEHAVIOR
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- RECOGNITION OF ROLE OF MITIGATION SYSTEMS DEVELOPMENT OF ACCIDENT MANAGEMENT PROCEDURES o THE IPEM SHOULD PROVIDE A REALISTIC RISK PROFILE i
i HENCE FOCUSONCONTAINMENTFAILUREMECHANIhMANDTIMING SIMPLY LOOK UP RELEASES FROM LABELS PREPARED ON THE BASIS OF 1
REFERENCE PLANTS EVALUATIONS 1 IFTEGRATE SYSTEMS RESPONSE (PROBABILISTICALLY) INTO SIMPLIFIED, BUT REALISTIC, CONTAINMENT EVEllT TREES (ALLOW FOR RECOVERY OR OTHER ACCIDENT MANAGEMENT PROCEDUPES)
EXAMINE ALL CLASSES OF SEQUENCES WITH SIGNIFICANT PROBABILITY 1 -
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GENERIC ISSUES-STAFF GUIPANCE I
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c CONSIDER SEPARATELY "HIGH" AND~" LOW" PRESSURE SCENARIOS .
LOW PRESSURE VIA PEPRESSURIZATION SYSTEM l
DISCAPD HIGH PRESSURE IF DEPRESSURIZATION RELIABLE l
O o MAIN HIGH PRESSURE SCENARIO ISSUES DIRECT CONTAINMENT HEATING (EFFECT OF GEOMETRY) .
SG TUPE FAILURE
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HYDROGEN EXPLOSIONS OP. DETONATIONS j l
ENHANCED SOURCE TERMS o MAIN LOW PRESSURE SCENARIO ISSUES
- CRUSTING VS, QUEFCHING 0F DEEP MELT COVERED WITH WATER l
l HYDROGEN STRATIFICATION IN THE PRESENCE OF CONDENSATION 0 AIM IPEM TO DEVELOP EVENT TREES THAT COVER RANGE OF UNCERTAINTY [
(ALSO COLLECT INFORMATION THAT LIKELY HAS BEARING ON THE ABOVE ISSUES). f 30
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o DOCUMENTATION-PROVIDE TFE BASES FOR THE FINDINGS IN A TRACEABLE MANNER.
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TVO TIERS OF DOCUMENTATI0PS
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TIEP-1 REPORTS THE RESULTS OF THE EXAMINATION TO NRC ,
o LIST THE DOMINANT SEQUENCES AND SCREEFING CRITERIA '
o THE CORE DAMAGE FREQUENCY AND THE LIKELIHOOD OF i
LARGE RELEASE o IDENTIFY AND LIST THE MAIN CONTRIBUTORS FOR CDF AND CONTAINMENT FAILURE TIER-2' DOCUMENTS THE EXAMINATION AFD WOULD BE RETAINED BY LICENSEES l
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l SCHEDULE j l
i c THE IPEM, GUIDELINES 8 CRITERIA, SCOPE OF THE EXAtilNATION AND GENERIC LETTER HAVE PEEN DISCUSSED WITH THE ACRS SUBCOMMITTEE. A FINAL MEETING ON THE SUBJECT WITH THE SUBCOMMITTEE IS BEING SCHEDULED FOR MAY 28, 1987. ACRS MEETING AND LETTER IS EXPECTED !N JUNE 1987, f o AN INF0FFAT10N MEETING WITH CF.GP WAS HELD IN OCTOBER 1986.
CRGR METING WILL BE SCHEDULED FOR JUNE 1987, '
A COMMISSION MEETII'G FOR APPROVAL OF ISSUANCE OF THE GENERICI f
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LETTER WILL BE SCHEDULED F0F JULY 1987.
o ISSUE GENERIC LETTERS WITH REQUEST F0.R INDIVIDUAL PLANT EXAMINATIONS (IPEs) (JULY 1987) l c CONDUCT REGIONAL MEETING WITH UTILITIES TO DISCUSS THE IPE !
l PROCESS c LICENSEE SUEMIT ACTUAL SCHEDULE IN 90 DAYS.
0 IPEs ARE EXPECTED TO BE COMPLETED IN 2 1/2 YEARS.
c PPIORITY FOR IPE i
IsT PLANTS WITH NO PPEVIOUS EXAMINATIONS 2ND PLANTS WITH EXISTING PRA AND !PEM TEST PLANS 3RD PLANTS WHICH WILL PERFORM A FULL-SCOPE PRA AND NEED MOR TIME, ~
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IPE RESULTS AND REVIEW PLAN a
o EXPECTED ACCOMPLISHMENTS AND BENEFITS FROM THE IPE .
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IDENTIFICATION AND ASSESSMENT OF POTENTIAL SEVERE ACCIDENTS CONTRIBUTORS (HARDWAP.E, PROCEDURES, TRAINING, MAINTENANCE) e IMPROVEMENTS TO PREVEFT AND MITIGATE 3EVERE ACCIDENTS.
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-1 IMPROVED CONTAINMENT PERFORMANCE. .
1 DEVELOPMENT AND IMPLEMENTATION OF A SEVERE ACCIDENT .
l MANAGEMENT PROGRAM.
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UNDERSTAND WHAT COULD POSSIBLY-G0 WRONG IN A PLANT l
l i DE PREPARED TO HANDLE THESE EVENTS.
c PES REVIEW PLAN FOR THE IPE - - . .
s o PREPARE A IPE REVIEW PLAN F0F NRR REVIEWERS T0:
IDENTIFY AREAS OF REVIEF ACCEPTANCE CRITERIA ,
ACTION LEVELS SAMPLE EVALUATIONS f ,
INTERFACES WITH OFFICE OF RES
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h, o ' REVIEW AT LEAST ONE PLANT SELECTED IN EACH CATEGORY
- 1.E. LARGE DRY, W, CE AND B8W TCE CONDENSER SUBATMOSPHERIC BWR, MARK I, MARK 11 AND MARK III
- PREFERABLY, THE PLANTS SELECTED ARE THOSE THAT (3) USED IDCOR IPEM AND (2) HAVE NO PRA.
COORDINATE WITH NRR IF ANY ADDITIONAL ACTIONS ARE NEEDED' (1.E., EEYOND THOSE TAKEN BY THE LICENSEES-THEMSELVES)
AND ON HOW TO PROCEED.
O PLANT WITH FULL-SCOPE PRA TO BE REVIEWED BY PRAB/DRAA/RES o THE REMAINING PLANTS TO BE REVIEWED BY DEST AND DRPER OF NRF.
c CONTINUED SUPPORT TO NRR DURING ITS REVIEWS TO KEEP CURRENT WITH RES DEVELOPMENTS AND GUIDE THE USE OF SUCH DEVELOPMENTS IN REVIEWIMG THE IPEs.
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1986 -
APRIL 3 NRC/lDCOR MEETING ON REVIEW STANDARD MAY 2 IDCOR IPEM DRAFT REPORTS SUBMITTED TO NRC 1 MAY 14/15 MAY 19 IDCOR IPEM WORKSHOP PRESENTED TO NRC
[
NRC'C0 ORDINATION MEETING FOR REVIEW 0F IPEM JUNE 19- NRC MEETING TO CONSOUDATE REVIEW' COMMENTS a JUNE 25 NRC REVIEWER'S PREUMINARY EVALUATIONS, 1 JUNE 26 5 IDCOR IPEM APPUCATIONS-DRAFT REPORTS SUBMITTED:TO NRC SEPTEMBER 9 NRC PREUMINARY EVALUTION SUBMITTED T0 IDCOR SEPTEMBER 24 !PEM MTG. WITH ACRS CLASS 9 SUBCOMMITTEE !
NOVEMBER 17/18 NRC AUDIT AT MP&L FOR GRAND GULF IPE d DECEMBER 3 CALVERT CUFFS DRAFT IPE REPORT SUBMITTED TO NRC ;
DECEMBER 12 IDCOR RESPONSES TO NRC IPEM COMMENTS DECEMBER 16 IDCOR IPEM REV 01 SUBMRTED TO NRC DECEMBER 18 NRC/IDCOR ON VULNERABluTIES, DECEMBER 19 IPEM MTG. WITH ACRS CLASS 9 SUBCOMMRTEE -!
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, SUV V ARY 0~ PE M LESTOs ES , ;..
1987 1 H
JANUARY RECEIPT OF GRAND GULF APPUCATIONS REPORT JANUARY 29 NRC/IDCOR'MTG. ON SOURCE TERM METHODOLOGY.
FEBRUARY 5 NRC/IDCOR 'MTG. ON BWR IPE METHOD 0 LOGY !
FEBRUARY 10/11 NRC AUDIT AT TVA ON-SEQUOYAH IPE FEBRUARY 12/13 NRC AUDIT AT DUKE POWER ON OCONEE IPE j FEBRUARY 19/20 NRC AUDIT AT LILC0 ON SHOREHAM IPE MARCH 1 RECEIPT OF SEQUOYAH APPLICATIONS REPORT MARCH 1 IDCOR IPEM REV 02 SUBMITTED TO NRC MAY NRC REGIONAL WORKSHOPS ON GENERIC LETTER /IPEM MAY -
IDCOR REGIONAL WORKSHOPS ON IPEM l i 3
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0 OVERVIEW OF THE IDCOR INDIVIDUAL PLANT '
EVALUATION METHODOLOGY ROBERT E. HENRY FAUSKE & ASSOCIATES, INC.
MAY 28,1987 >
WASHINGTON, D.C.
j l
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e l
i l
N l PRESENTATION OUTLINE -
1 .
e REVIEW THE GOALS OF THE IPE METHODOLOGY.
i e REVIEW THE " SYSTEM" IMPORTANCE IN THE PLANT ANALYSIS. ;
e REVIEW THE " SYSTEM" IMPORTANCE IN THE SOURCE TERM EVALUATION.
e REVIEW THE INTERACTIONS BETWEEN THE PLANT l ANALYSIS AND SOURCE TERM EVALUATION. i i
e e
e
~
L
\
INDIVIDUAL -PLANT EVALUATION METHODOLOGY .
l i
'* OPERATOR ACTlogg gySTEMS AVAILAst SEQUENCE oEFINITion-
^
SOURCE
[ SYSTEM TERM ]
(PLANT) . '
I ASSESSMENT ANALYSIS CHECK ON THE g 57 EMS AVAILABkN i
08 I NIAINMENT ISOLA _
\ I
\ j EVALUATION OF IMPROVED ,\ g POTENTIAL OUTLIER success l
\ CONDITIONS CRITERIA l
\
' I MAAP MODULAR ACCIDENT ANALYSIS PROGRAM ,
i 1
]
I
I BWR AND PWR IPE METHODOLOGIES i l
1 e SYSTEM ORIENTED.
. - INCLUDES FRONT LINE SYSTEMS.
~
. - INCLUDES SUPPORT SYSTEMS.
e POWER (AC/DC).
e WATER.
e CONTROL.
e OPERATIONALLY ORIENTED.
- PLANT HISTORY / DATA. I e INITIATORS.
e SYSTEM PERFORMANCE. -
e COMPONENT PERFORMANCE.
- PLANT MAINTENANCE PROCEDURES AND HISTORY.
- PLANT SURVEILLANCE PROCEDURE.
o PROCEDURALLY ORIENTED.
- PLANT HISTORY.
- OPERATOR TRAINING IN EOPs/FRGs.
- ADDITIONAL PLANT SPECIFIC PROCEDURES. !
m 96
4 9
EXAMPLES OF IMPROVED SUCCESS CRITERIA l
BWRs e CRD FLOW FOR EVENTS WITH SUCCESSFUL SCRAM AND LOSS OF ECCS SYSTEMS ON DEMAND. .
e ATWS RELATED EVENTS WITH OPERATOR ACTIONS FOLLOWING PLANT SPECIFIC EOPs.
PWRs e LOCA EVENTS WITH STEAM GENERATOR DEPRES-SURIZATION (REFLUX COOLING) WITH SUBSEQUENT RECOVERY OF ECCS SYSTEMS.
e FEED AND BLEED CONDITIONS.
t l
l a
. - _ _ _ - _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - - - - _ - _ _ - _ - - _ - - _ . _ - _ _ - _ . - - _ _ _ - - _ _ _ . _ _ _ - _ - . -- - - - _- ----_----_--_------A
4 SCOPE OF THE METHODOLOGY o ADDRESSES INTERNAL EVENTS.
o' NOT A PRA, BUT THE-SYSTEMS ANALYSIS CAN BE EXPANDED TO A LEVEL 1lPRA.
o SYSTEM MODELS ARE ASSEMBLED AT A HIGH LEVEL. ,
o INCLUDES CRITICAL SAFETY FUNCTIONS AND FRONT LINE SYSTEMS. WHICH FULFILL THESE. ' '
FUNCTIONS. .
o FRONT LINE SYSTEMS INCLUDE BOTH SAFETY AND NON-SAFETY RELATED SYSTEMS.
o SUPPORT SYSTEMS AND THEIR DEPENDENCIES ARE EXPLICITLY ADDRESSED.
- AC POWER.
- DC POWER.
Y
- e
___m____ _ _ _ _ _ __________._____-__mm______.-_________.___.-.________________:._______________________m.__ - - - _. __ .-____ ._. - _ _ . - . _ _ _ _ _ . _ _ _ _ _ _
4 l
4 i
SYSTEM NOTEBOOK FORMAT !
I
- I e FUNCTION e SYSTEM DESCRIPTION ,
- SUPPORT SYSTEMS
- INSTRUMENTATION AND CONTROL !
- TEST AND MAINTENANCE
- TECHNICAL SPECIFICATION LIMITATIONS -,
e SYSTEM OPERATION e PERFORMANCE DURING ACCIDENT CONDITIONS e LOCATION WITHIN THE PLANT e OPERATING EXPERIENCE e LOGIC MODELS .
e INITIATING EVENT REVIEW e QUANTIFICATION e
SUMMARY
OF. KEY FINDINGS e
SUMMARY
OF KEY REVIEW COMMENTS e REFERENCES O
1 TABLE 2.2-9 l EXAMPLE IMPACT VECTOR ANALYSIS a w 5 i
= 5 E e5 ,? 5 l E !' 3 ' & d.
S 'T 3 e E ? o 8 2 %t% - * -
w % .- c' % .h: ? .,
E 3 E' E E ~~ E 5E x3h $E $$
Bi
- % 5% 3% 0% b i f ' '";i T, ~;i % Simplified J
Support Systems mA g,t: 3A t ,t: h a ;,3: q ,3- )
Operational State j $ v a g g;u a a Suppert ,
a Cembinatiens State 1 A+B A+B A+B A+B A+B A,84 A+B A+B 1 2 A+B A+B A A A A+C A A 2 l 3 A+B A+B B B B B+C B B 2 4 A+B A+B - - -
C - -
3 -
1 5 A+B A A+B A A~ A B+C A 'A 2 '
6 A+B A A A A A+C A A 2 7 A+B A B B+C 3 B A+B A - -
C 3 9 A+B B A+B B B A,B+C B B 2 10 A+B B A -
A+C 3 11 A+B B B B B B+C B B '2 12 A+B B- -
C 3 13 A+B -
A+B - -
'C - -
3 14 A+B -
A -
C 3 15 A+B -
B - -
C - -
3-16 A+B - - - -
C - -
4 Offsite AC Available/Offsite AC Unavailable .
17 A+B A+B A+B A+B A+B A, B+C A+B A+B 5 1B A+B A+B A A A A+C A A 6 19 A+B A+B B B B B+C B B 6 20 A+B A+B - -
C 7 21 A+B A A A A A+C A A 6 22 A+B A C 7 23 A+B B B B B B+C B B 6 24 A+B B C 7 25 A+B C 7 1 l
26 A A A A A A+C A A 6 27 A - - -
C 7 2B A C 7 29 B B B B E B+C B B 6 30 B B -
C 7 31 B C 7 32 - - - - - - - -
8 ,
"'*8'"
2-109
/
m -
l E____ ____ _ . . _ _ _ _ _ . _ _ _ _ . _ -_ . _ _ _
LIST OF SUPPORT SYSTEMS 4
A. SERVICE WATER B. ENGINEERED SAFETY FEATURES ACTUATION C. COMPONENT COOLING ,
D. ELECTRIC POWER - OFFSITE AC E. ELECTRIC POWER - ONSITE AC GENERATORS .
F. ELECTRIC POWER - ONSITE DC G. INSTRUMENT AIR H. INTEGRATED CONTROL SYSTEM
- l. HVAC l
i j
'- m _. _ _ _ _ . _ _ _ _ _ , . ______m
. . 4
,m SYSTEM DEPENDENCE MATRIX 1
1 I
2 E5 .=
'E E ss; e 8 &l; e 5
- 8 8 8 2' "
3 e . . . F A& .
Exa=ple Matrix f8 ggg '
o o
o C.J j
E (Read Acress) I Tu s sT 3
'b % 2 2 3 8 a: E. 2 m
8 s3 3 3 8 3' E '
'5, 3 8 'M 8 8- C. % W i 5 5 C C C oa5 E -
l Engineered Safety Features X X X .X {
Integrated Control System X X X X !
Electric Power - Offsite AC Electric Power - Onsite AC X X X X ,
Electric Pcwer - Onsite DC X X X - X 1 Component Cooling Water X X X Service Water System X X X Instrument Air System X X HVAC System X X X l Auxiliary / Emergency Feedwater X X X X X l High Pressure Safety Injection X X X X X X . l Low Pressure Safety Injection X X X X X X High Pressure Recirculation X X X X X X Low Pressure Recirculation X X X X X X Chemical Volume & Control System X X X X X Main Feedwater System X X X X X Main Steam System X X Condensate System X X X X Accumulates / Core Ficed Tanks Containment Fan /Ceciers X X X X X X Containment Spray System X X X X X X ,
Recirculation Spray System X X X X X Quench Spray System X X X X X X Ice Condenser System
. A X Turbine Bypass System X X Reacter Prctection System X X X X P2R Power Operated Relief Valves X
1
,~
IPE SOURCE TERM METHODOLOGY BWR 1 l
l MARK I AND 11 CONTAINMENTS , l
\
DE!PENDENCE BETWEEN PRIMARY SYSTEM AND CONTAIN-MENT REQUIRES THE USE.OF STREAMLINED CONTAIN- '
MENT EVENT TREES FOR EVALUATING RELEASES. l 1
KEY ELEMENTS: .
e CONTAINMENT FAILURE / VESSEL FAILURE. I e WETWELL VENTING.
e DRYWELL SPRAYS.
e DEBRIS TRANSPORT TO THE SUPPRESSION POOL.
MARK 111 CONTAINMENT 4 i
RELEASES FOR ALL ACCIDENT SEQUENCES ARE ESSENTIALLY NOBLE GASES.
A g
e
o .. .
.o IPE SOURCE TERM METHODOLOGY PWR j i
\
ICE CONDENSERS ESSENTIALLY THE SAME AS SEQUOYAH. 1 LARGE DRY -
o INDEPENDENCE OF PRIMARY SYSTEM AND CONTAINMENT AND PREVIOUS MAAP ANALYSES ALLOW A SIMPLIFIED MODELING APPROACH. KEY ELEMENTS ARE: ;
e TIME FOR DEBRIS DRYOUT IN CONTAINMENT.* !
e TIME OF CONTAINMENT FAILURE.
e INERT AEROSOL GENERATION RATE.
e AEROSOL SETTLING RATES.
e TELLURIUM AND OTHER NONVOLATILE RELEASES.
USES STREAMLINED CONTAINMENT EVENT TREES TO REPRESENT SEQUENCE DEPENDENCE.
l i
- I l
STREAMLINED CONTAINMENT EVENT TREES i
l e FOCUS ON THE MAJOR FISSION PRODUCT RETEN- '
~ TION MECHANISMS IN THE CONTAINMENT.
e ALLOW A STRUCTURED METHOD OF SORTING THE VARIOUS SOURCE TERMS ON A SEQUENCE SPECIFIC BASIS. .
e ARE SUFFICIENT FOR IDENTIFYING OUTLIER CONDITIONS.
- l. __ m.___-_____ _ ._ ______ ____-- _____._.-_-