ML14176A447
| ML14176A447 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 07/11/1989 |
| From: | Lo R Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8907200090 | |
| Download: ML14176A447 (29) | |
Text
-pR REG(,
A oUNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 July 11, 1989 Docket No.
50-261 LICENSEE: CAROLINA POWER & LIGHT COMPANY FACILITY: H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 (HBR-2)
SUBJECT:
MEETING
SUMMARY
OF MAY 24, 1989 MEETING ON PROBABILISTIC RISK ANALYSIS APPLICATION A meeting between the NRC staff and representatives of Carolina Power & Light Company (CP&L), the licensee, was held on May 24, 1989 to discuss the application of probabilistic risk analysis (PRA) to the Design Basis Documentation (DBD) program that CP&L is conducting for the HBR-2 facility. The list of attendees and a copy of the view-graphs that CP&L used in its presentation during the meeting are enclosed as Enclosures 1 and 2, respectively. The following is a summary of the meeting.
Identification of Issue During the DBD effort, CP&L had identified discrepancies between the intendedk function of safety equipment and the actual design/as-built equipment. These discrepancies were not of a nature such that the equipment in question would nominally be incapable of performing its safety function, (e.g., error in equipment sizing such that safety function could not be accomplished even when the system performs mechanically according to specification). Rather, these discrepancies would surface only under specific operational challenges or accident and single failure scenarios. Because of the specific nature of these scenarios, the probability of events leading to core damage could be extremely low.
For these situations, CP&L proposes to explore the circumstances for operational flexibility; i.e, instead of being restricted to declaring the system inoperable and subject the facility to a shutdown transient per Technical Specifications (TS) once the discrepency is identified, CP&L proposes to justify alternative approaches through PRA while long-term disposition of the discrepancy is being evaluated and planned.
The Proposed PRA Application CP&L proposes to apply PRA based Discrepancy Screening Criteria (DSC, Enclosure
- 3) for its action in response to an identified discrepancy. According to the DSC, the discrepancy is classified by risk category based on the probability of the accident and failure scenario that can lead to core damage. The equipment related to the discrepancy would be declared inoperable only if the contribution to core damage (CCD) frequency is calculated to be greater than 1OE-4 per year.
Also, according to the DSC, the reportability and required corrective action Q 72'0009 8907 FDR ADOtCK 0500F261
- t'
-2 would also be based on the CCD and the assigned risk category. CP&L emphasized that for a discrepancy that falls in the "high risk" category (i.e., CCD greater than 1OE-4 per year), the affected equipment will be declared inoperable and the corresponding TS action statement and reporting requirements per 10 CFR 50.72 and 50.73 would apply.
Discussion of the Proposal The staff had a number of concerns and those were discussed with CP&L. The following are three main concerns:
(1) There are, inherent in PRA, certain degrees of uncertainty. The CCD values would be meaningful only if the level of confidence or associated error margin is specified for the particular case.
(2) The staff is concerned about the apparent inconsistency between the definitions of "operability" using the deterministic TS approach and the PRA based proposed DSC.
(3) The staff is concerned about the timeliness of notification under the proposed DSC.
Conclusion The staff recognizes the merits of PRA to supplement the information basis for an orderly and appropriate response when the DBD program identifies a discrepancy. Although the present policy would require a strict adherence to the deterministic TS definition of equipment operability, the licensee was encouraged to further explore the possibility of a more flexible PRA-based operability criteria; e.g., by a written request for a pilot program at HBR-2 or through the participation in an industry-group which has an on-going discussion with the staff on TS improvements. However, even without any programmatic changes, the staff recognizes the usefulness of PRA to supplement the licensee's justification for continued operation and to provide supporting information for the staff's consideration of discretionary enforcement or TS waiver action.
Following the May 24, 1989 meeting, C. Dietz et al., of CP&L met with R. Lo and H. Dance of the NRC at the HBR-2 site on June 14, 1989. CP&L states that it would continue its policy of declaring the equipment inoperable when DBD review identifies a discrepancy, regardless of risk consequences. CP&L would then strictly follow the Action Statement associated with the TS. For those cases where CP&L believes that there is adequate justification for continued operation, CP&L may request the necessary discretionary enforcement action.
PRA may be used as a supporting basis for the staff's consideration. The staff
-3 is expected to evaluate and consider, on a case-by-case basis, the discretionary enforcement request and the adequacy of the planned corrective action. PRA may also play a role in supporting the licensee's own decision/corrective action planning process; e.g., during the deliberations of the HBR-2 Plant Nuclear Safety Committee.
Original Signed By:
Ronnie Lo, Senior Project Manager Project Directorate II-1 Division of Reactor Projects -I/II Office of Nuclear Reactor Regulation PM:PDI D:
-1 RLo:sw ip EJ Wesam 6/10/89
/
89
Mr. L. W. Eury H. B. Robinson Steam Electric Carolina Power & Light Company Plant, Unit No. 2 cc:
Mr. R. E. Jones, General Counsel Mr. Dayne H. Brown, Chief Carolina Power & Light Company Radiation Protection Branch P. 0. Box 1551 Division of Facility Services Raleigh, North Carolina 27602 Department of Human Resources 701 Barbour Drive Raleigh, North Carolina 27603-2008 Mr. H. A. Cole Special Deputy Attorney General Mr. Robert P. Gruber State of North Carolina Executive Director P. 0. Box 629 Public Staff - NCUC Raleigh, North Carolina 27602 P. 0. Box 29520 Raleigh, North Carolina 27626-0520 U.S. Nuclear Regulatory Commission Mr. C. R. Dietz Resident Inspector's Office Manager, Robinson Nuclear Project H. B. Robinson Steam Electric Plant Department Route 5, Box 413 H. B. Robinson Steam Electric Plant Hartsville, South Carolina 29550 P. 0. Box 790 Hartsville, South Carolina 29550 Regional Administrator, Region II U.S. Nuclear Regulatory Commission Mr. Heyward G. Shealy, Chief 101 Marietta Street Bureau of Radiological Health Suite 2900 South Carolina Department of-Health Atlanta, Georgia 30323 and Environmental Control 2600 Bull Street Mr. R. Morgan Columbia, South Carolina 29201 General Manager H. B. Robinson Steam Electric Plant P. 0. Box 790 Hartsville, South Carolina 29550
DISTRIBUTION FOR MEETING NOTICE DATED:
May 24, 1989 Facility:
Robinson Unit 2 Ddcket File NRC PDR Local PDR PDHI-I Reading T. Murley 12-G-18 J. Sniezek 12-G-18 J. Partlow 12-G-18 S. Varga 14-E-4 G. Lainas 14-H-3 E. Adensam 14-B-20 P. Anderson 14-B-20 R. Lo 14-B-20 W. Lanning 11-E-22 OGC 15-B-18 E. Jordan MNBB-3302 B. Grimes 9-A-2 NRC Participants ACRS (10)
P-315 GPA/PA 17-F-2 V. Wilson 12-H-5 L. Thomas 12-E-4 B. Borchardt 17-D-19 A. El Bassioni 10-A-2 R. Barrett 10-A-2 P. Kellogg RII P. Burnett RH R. Carroll RH R. Jones 8-E-23 D. Tondi 8-0-20 G. Imbro 9-A-1
ENCLOSURE I LIST OF ATTENDEES MEETING
SUMMARY
MAY 24, 1989 Name Title Organization Ronnie Lo Project Manager NRR/PDII-1 Adel El-Bassioni Section Chief NRR/RAB Richard Barrett Branch Chief NRR/RAB Eve Fotopoulos SERCH Licensing Bechtel Larry Garner Sr. Resident Inspector Robinson Paul Kellogg Chief, Operational Program RH Paul Burnett Reactor Inspector NRC/RII Robert Carroll, Jr.
Project Engineer NRC/RII Robert Prunty, Jr.
Principal Eng.-Nuc Lic CP&L Robert Jones Section Chief NRR/SRXB Peter Kangt Electrical Engineer NRR/SELB William Flanagan Mgr. Modification Prog.
CP&L-RNPD Richard Anoba Project Engineer CP&L-CNS Joseph Curley Dir., Regulatory Coupl.
CP&L-Robinson Dominic Tondi Section Chief NRR/SELB E. G. Adensam Project Director NRR/PDII-1 C. R. Dieta Mgr. Robinson Nuclear Proj.
CP&L-Robinson
CAROLINA POWER & LIGHT COMPANY PRESENTATION TO NRC WHITE FLINT, MARYLAND MAY 24, 1989 PRA APPLICATION TO DESIGN BASIS RECONSTITUTION PROJECT H. B. ROBINSON UNIT NO. 2 KBW:89-1805(1)
AGENDA INTRODUCTION C. R. DIETZ NEED C. R. DIETZ H. B. ROBINSON MODEL R. E. OLIVER APPLICATION J. N. CURLEY W. J. FLANAGAN EXPERIENCE R. C. ANOBA IMPLEMENTATION/
SUMMARY
C. R. DIETZ KBW:89-1805(2)
NEED FOR APPLYING PROBABILISTIC METHODOLOGY TO DESIGN BASIS DOCUMENT RECONSTITUTION (DBDR) PROJECT
- DBDR EXPERIENCE
- DISCREPANCIES IDENTIFIED
- NO CLEAR METHOD TO BRIDGE ENGINEERING JUDGEMENT WITH TECHNICAL SPECIFICATION EQUIPMENT OPERABILITY DEFINITION
- PROPENSITY TO IMPOSE INTERIM CORRECTIVE ACTION ON OPERATORS KBW:89-1805(3)
NEED FOR APPLYING PROBABILISTIC METHODOLOGY TO DESIGN BASIS DOCUMENT RECONSTITUTION (DBOR) PROJECT BENEFITS
- PROVIDE CLEAR DEFINITION OF DISCREPANCY PRIORITY
- REDUCE "KNEE JERK" REACTION
- ADD ORDER TO DBDR PROJECT
- MINIMIZE UNNECESSARY TRANSIENTS ON PLANT
- MINIMIZE NEEDLESS "OPERATOR ACTION" INTERIM FIXES
- MORE EFFECTIVE UTILIZATION OF MANAGEMENT/TECHNICAL RESOURCES KBW:89-1805(4)
PROBABILISTIC RISK ASSESSMENT CP&L OBJECTIVES APPLY PRA AS INFORMATION TOOL USE INFORMATION TO EVALUATE ISSUES USE IN CONCERT WITH OTHER SOURCES, E.G. DETERMINISTIC ANALYSIS RISK ESTIMATE TO BE CONSIDERED DURING ENGINEERING JUDGMENT PROCESS RESULTS IN PERSPECTIVE PRIORITIZATION RESOURCE ALLOCATION KBW:89-1805(5)
PRA DEVELOPMENT HISTORY INITIATED IN CORPORATE NUCLEAR SAFETY ORGANIZATION PHASED APPROACH BEGAN IN 1983 SYSTEM-LEVEL ANALYSIS MULTI SYSTEMS ANALYSIS LIMITED SCOPE MODEL LEVEL I PRA LIMITED SCOPE LEVEL II PRA CURRENT MODELS BRUNSWICK/LEVEL I AND LIMITED SCOPE LEVEL II HARRIS/LEVEL I ROBINSON/"FUNCTIONAL" LEVEL I APPROACH HAS RESULTED IN DEVELOPMENT OF IN-HOUSE EXPERTISE TO APPLY AND MAINTAIN PRAs GOALS ARE APPLICATIONS TO EMERGING ISSUES FOR RISK MANAGEMENT AND RESPONSIVENESS TO SEVERE ACCIDENT POLICY KBW:89-1805(6)
PERSONNEL EIGHT PEOPLE WITH HANDS-ON EXPERIENCE FORMAL PRA COURSES SYSTEMS APPLICATIONS INTENSIVE TRAINING/LEARNING DURING HARRIS AND BRUNSWICK PRA PROJECTS EXPERTISE IN FAULT-TREE ANALYSIS MODEL INTEGRATION/QUANTIFICATION DATA ANALYSIS HUMAN RELIABILITY EXTERNAL EVENTS DEMONSTRATED BY PRODUCTION OF HARRIS LEVEL I PRA INDEPENDENT PEER REVIEW BY OUTSIDE EXPERTS (S.
LEWIS, J.
GAERTNER, G. HUGHES, G. PARRY, J. STETKAR)
KBW:89-1805(7)
ROBINSON MODEL
- INITIATED IN PARALLEL WITH HARRIS MODEL
- DEVELOPED FROM HARRIS SYSTEMS' MODELS AUGMENTED BY ROBINSON SPECIFICS
- MINIMAL OUTSIDE CONTRACTOR ASSISTANCE (HRA ONLY)
- UTILIZED PROVEN CP&L EXPERTISE
- INCORPORATES LESSONS LEARNED FROM HARRIS EFFORT KBW:89-1805(8)
ROBINSON MODEL STATUS TASKS COMPLETED (80+%)
CP&L ACCIDENT SEQUENCE DEVELOPMENT INITIATING EVENTS IDENTIFICATION ACCIDENT SEQUENCE DESCRIPTION/EVENT TREE DEVELOPMENT RESPONSE SYSTEMS SUCCESS CRITERIA SYSTEMS FAULT TREE DEVELOPMENT COMPONENT DATA BASE DEVELOPMENT (GENERIC)
PRA MODEL SOLUTION ACCIDENT SEQUENCE QUANTIFICATIONS SIMULATOR TRAINING INSIGHTS KBW:89-1805(9)
ROBINSON MODEL STATUS TASKS REMAINING INCORPORATE RECENT MODIFICATIONS HUMAN RELIABILITY ANALYSIS LOCAL OPERATOR ACTIONS ASSESSMENT QUANTIFICATION OF OPERATOR ACTIONS/RECOVERIES DATA REFINEMENT EQUIPMENT EXPOSURE TIMES RISK-SIGNIFICANT COMPONENT IDENTIFICATION FOR PLANT SPECIFIC DATA ANALYSIS INTERNAL (SITE/CORPORATE OFFICE) REVIEW REPORT COMPLETION INDEPENDENT (EXTERNAL PEER) REVIEW INCORPORATE REVIEW COMMENTS TARGETED COMPLETION WITHIN 3 MONTHS KBW:89-1805(10)
DESIGN BASIS DOCUMENT RECONSTITUTION (DBDR)
PROJECT APPLICATION COMPLEMENT ENGINEERING JUDGEMENT DBDR/PRA DISCREPANCY SCREENING CRITERIA
- DEFINE VITAL EQUIPMENT OPERABILITY
- NOT TO SUPERCEDE TECHNICAL SPECIFICATIONS
- NOT TO SUPERCEDE FSAR CHAPTER 15 ASSUMPTIONS
- PRIORITIZE DISCREPANCY RESOLUTION KBW:89-1805(11)
DBD/PM DISCREPANCY SCREENING CRITERIA CONTRIBUTION TO RISK CORE DAMAGE/YR AFFECTED REPORTABILITY REQUIRED CATEGORY (CCD)
EQUIPMENT ACTION TECH. SPEC. ACTION STATEMENTS HIGH CCD> E-4 INOPERABLE 10CFR50.72 & 73 PREVAIL UNTIL CORRECTIVE ACTION IMPLEMENTED MODERATELY E-4 > CCD > E-5 OPERABLE NOTIFY REGION II PROVIDE CORRECTIVE ACTION PLAN TO HIGH WITHIN 24 HOURS REGION 11 WITHIN 30 DAYS MODERATE E-5 > CCD > E-6 OPERABLE NOTIFY REGION II PROVIDE CORRECTIVE ACTION PLAN TO WITHIN 72 HOURS REGION 11 WITHIN 90 DAYS LOW E-6 > CCD > E-7 OPERABLE NOTIFY REGION 11 INCORPORATE CORRECTIVE ACTION WITHIN 30 DAYS INTO 5-YEAR BUSINESS PLAN INSIGNIFICANT CCD < E-7 OPERABLE REVIEW WITH DOCUMENT IN DBD SENIOR RESIDENT KBW:89-1805(13)
DESIGN BASIS RECONSTITUTION DISCREPANCY IDENTIFICATION/DISPOSITION IDENTIFY DISCREPANCY SAFETY RELATED EQUIPMENT POTENTIALLY REDUCED SAFETY MARGIN SIGNIFICANT LICENSING COMMITMENT COST IMPACT >$100,000 VERIFIED SIGNIFICANT PAR NOTIFY PLANT NOTIFY NRC TECH SPEC OPERABILITY COMPLIANCE COMPLY WITH LICENSE
DESIGN BASIS DOCUMENT RECONSTITUTION DISCREPANCY IDENTIFICATION/NOTIFICATION DISCREPANCY IDENTIFIED DESIGN/
LICENSE NO DOCUMENT DISCREPANCY DISPOSITION YES POTENTIALLY NO SIGNIFICANT YES VERIFIED NO SIGNIFICANT:
YES NOTIFY PLANT MANAGEMENT INITIATE PR NOTIFY NRC PNDE 318E
DESIGN BASIS RECONSTITUTION DISCREPANCY IDENTIFICATION/OISPOSITION SIGNIFICANT DEFICIENCY; PLANT NOTIFIED YES TECH SPEC REQUIREMENTS CLER?
NO FSAR NO DETERMN COMPLIANCE?
EXTENTO NONCOMPLAC YES SYSTEM YES OPERABLE?
00CUIEN NO NO TECH SPEC YES COMPLIRNCE?
00CUMEN LIENEPNSC PNSC REPORTS NOTIFY C
APPLICATIONS EXPERIENCE PROGRESSED SIMILARLY TO PRA EXPERTISE DEVELOPMENT SYSTEM RELIABILITY ANALYSIS INDIVIDUAL SEQUENCE ANALYSIS FUNCTIONAL SEQUENCE ANALYSIS LEVEL I PRA LESSONS LEARNED THROUGH APPLICATIONS EXAMPLES:
DB-50 CIRCUIT BREAKERS SAFETY INJECTION ABT SCHEME MOTOR CONTROL CENTER RHR PIT FLOODING KBW:89-1805(15)
DB-50 CIRCUIT BREAKERS THREE PHASE BOLTED FAULT RESULTS IN FAULT CURRENTS THAT EXCEED THE MAXIMUM INTERRUPT RATING OF DB-50 BREAKERS ON EMERGENCY BUSSES FAILURE OF DB-50 BREAKERS WAS POSTULATED TO CAUSE FAILURE OF BOTH EMERGENCY BUSSES PERFORMED PRA ANALYSIS ON INDIVIDUAL SEQUENCES CORE DAMAGE FREQUENCY CONTRIBUTION - 1.4E-6/Y DOMINATED BY FAILURE TO ACTUATE THE DEDICATED SHUTDOWN SYSTEM MODIFICATION TO UPGRADE BREAKERS (PLANNED 1990 REFUELING)
MODERATE RISK PER PROPOSED SCREENING CRITERIA KBW:89-1805(16)
SAFETY INJECTION SYSTEM AUTOMATIC BUS TRANSFER SCHEME SINGLE FAILURES IN THE AUTOMATIC TRANSFER SCHEME WAS POSTULATED TO CAUSE INSUFFICIENT INJECTION FLOW DURING A SMALL LOCA EVENT PERFORMED PRA ANALYSIS TO ASSESS THE AUTOMATIC TRANSFER SCHEME FOR A SMALL BREAK LOCA SEQUENCE DURING THE INJECTION PHASE.
CORE DAMAGE FREQUENCY CONTRIBUTION - 5.8E-7/Y PLANT SHUTDOWN FOR MODIFICATIONS LOW RISK PER PROPOSED SCREENING CRITERIA KBW:89-1805(17)
MOTOR CONTROL CENTER DESIGN BASIS RECONSTITUTION PROJECT DISCOVERED A POSTULATED FAILURE OF BOTH VITAL MOTOR CONTROL CENTERS AUTOMATIC STARTS OF MCC LOADS AFTER TURBINE AUXILIARIES ARE RUNNING COULD CAUSE AN OVERLOAD THAT WOULD FAIL BOTH MCC'S PERFORMED FUNCTIONAL SEQUENCE ANALYSIS USING LEVEL 1 PRA MODELS NO EFFECT ON SHORT TERM SEQUENCES, SIGNIFICANT EFFECT ON LONG TERM SEQUENCES INTERIM COMPENSATORY ACTIONS INCLUDED SPECIAL PROCEDURE TO CONTROL LOADS I
CORE DAMAGE FREQUENCY CONTRIBUTION BEFORE COMPENSATORY ACTIONS - 1.4E-5/YR MODERATELY HIGH RISK PER PROPOSED SCREENING CRITERIA CORE DAMAGE FREQUENCY CONTRIBUTION AFTER COMPENSATORY ACTIONS - LESS THAN I.OE-6/Y LOW RISK PER PROPOSED SCREENING CRITERIA KBW:89-1805(18)
RHR PIT FLOODING DESIGN BASIS RECONSTITUTION PROJECT DISCOVERED A POTENTIAL COMMON CAUSE FAILURE OF BOTH RHR PUMPS DUE TO FLOODING IN THE RHR PIT USED THE LEVEL I PRA MODEL TO PERFORM A FUNCTIONAL SEQUENCE ANALYSIS EVALUATED FUNCTIONAL SEQUENCES THAT WERE IMPACTED BY THE POSTULATED COMMON CAUSE FAILURE OF THE RHR SYSTEM CORE DAMAGE FREQUENCY CONTRIBUTION - 5.OE-6/Y DOMINATED BY RHR PUMP SEAL FAILURES REVISED EOP NETWORK TO SPLIT RHR TRAINS PRIOR TO INITIATING LONG TERM RECIRCULATION (INTERIM)
MODERATE RISK PER PROPOSED SCREENING CRITERIA KBW:89-1805(19)
IMPLEMENTATION RHR EXPERIENCE PROMPTED ACTION REGION II PRESENTATION - APRIL 27, 1989 PNSC ENDORSEMENT OF PRA AS DECISION MAKING PROCESS FOR DBDR PROJECT - MAY 4, 1989 NRR PRESENTATION - MAY 24, 1989 INCORPORATE PROCESS INTO APPROVED PROCEDURES (APPROXIMATELY 30 DAYS)
REVISED RHR JCO TO PNSC - JUNE, 1989 PROCEDURES REVISED TO REMOVE "INTERIM" OPERATOR ACTION JULY, 1989 REVIEW PROCESS FOR ENHANCEMENT - DECEMBER, 1989 KBW:89-1805(20)
CONCLUSION RECOGNIZED NEED FOR PROCESS TO PROVIDE MORE STRUCTURE TO DBOR DISCREPANCY RESOLUTION PRA IS A REASONABLE MEANS TO COMPLEMENT ENGINEERING JUDGEMENT TO ADD THIS STRUCTURE RHR APPLICATION WILL ELIMINATE ADDITIONAL OPERATOR ACTIONS DURING ECCS INJECTION/RECIRC PHASE SWITCH-OVER CRITERIA/ACTION DEFINED IS REASONABLE AND CONSISTENT WITH CURRENT INDUSTRY DIRECTION RESULTS IN OVERALL BENEFIT TO PUBLIC HEALTH AND SAFETY KBW:89-1805(21)
DBD/PM DISCREPANCY SCREEN NG CRITERIA CONTRIBUTION TO RISK CORE DAMAGE/YR AFFECTED REPORTABILITY REQUIRED CATEGORY (CCD)
EQUIPMENT ACTION TECH. SPEC. ACTION STATEMENTS HIGH CCD> E-4 INOPERABLE 10CFR50.72 9 73 PREVAIL UNTIL CORRECTIVE ACTION IMPLEMENTED MODERATELY E-4 > CCD > E-5 OPERABLE NOTIFY REGION II PROVIDE CORRECTIVE ACTION PLAN TO HIGH WITHIN 24 HOURS REGION 11 WITHIN 30 DAYS MODERATE E-5 > CCD > E-6 OPERABLE NOTIFY REGION II PROVIDE CORRECTIVE ACTION PLAN TO WITHIN 72 HOURS REGION 11 WITHIN 90 DAYS LOW.
E-6 > CCD E-7 OPERABLE NOTIFY REGION 11 INCORPORATE CORRECTIVE ACTION WITHIN 30 DAYS INTO 5-YEAR BUSINESS PLAN INSIGNIFICANT CCD < E-7 OPERABLE REVIEW WITH SENIOR RESIDENT KBW:89-1805(13)