IR 05000275/1991021
| ML16341G213 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/15/1991 |
| From: | Morrill P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML16341G212 | List: |
| References | |
| 50-275-91-21-MM, 50-323-91-21, NUDOCS 9108050037 | |
| Download: ML16341G213 (46) | |
Text
Licensee:
Pacific Gas and Electric Company 77 -Beale Street, Room 1451 San Francisco, California 94106 Facility Name:
Diablo Canyon Units 1 and
Meeting at:
Region V Office, Walnut Creek, California Report Prepared by:
B. J.
Olson, Project Inspector U.S.
NUCLEAR REGULATORY COMMISSION
REGION V
Report Nos.:
50-275/91-21 and 50-323/91-21 Docket Nos.:
50-275 and 50-323 License Nos.:
~ e
~
g Approved by; orr>,
ie Reactor Projects Section
7
]S te
)gne
~ r Meetin on June
1991 (Re ort Nos.
50-275/91-21 and 50-323 91-21)
A meeting was held in the Region V Office, Walnut Creek, California to discuss
.~:=
the licensee s Probabilistic Risk Assessment Program.
9108050037 910715 PDR ADOC/( 05000275 A
U.S.
NUCLEAR REGULATORY COMMISSION
REGION V
Report Nos.:
50-275/91-21 and 50-323/91-21 Docket Nos 50-275 and 50-323 License Nos.:
Pacific Gas and Electric Company 77 Beale Street, Room 1451 San Francisco, California 94106
- Facility Name:
Diablo Canyon Units 1 and
Meeting at:
Region V Office, Malnut Creek, California Report Prepared by:
B. J.
Olson, Project Inspector Approved by:
orrl, le Reactor Projects Section
7 iS te 1gne Meetin on June
1991 (Re ort Nos.
50-275/91-21 and 50-323 91-21)
A meeting was held in the Region V Office, walnut Creek, California to discuss the licensee's Probabilistic Risk Assessment Progra I'
l.
~Nti Att d
DETAILS a.
Licensee Attendees J. Shiffer, Senior Vice President and General Manager Nuclear Power Generation Business
.Unit W. Fujimoto, Vice President, Nuclear Technical Services J.
Tompkins, Director, Nuclear Regulatory Affairs J. Gisclon, Supervising Nuclear Generation Engineer E. Connell, Manager, Nuclear Operations Support R. Thierry, Senior Engineer J.
Liu, Senior Engineer b.
NRC Attendees J. Martin, Regional Administrator R.
Zimmerman, Director, Division of Reactor Safety and Projects K. Perkins, Deputy Director, Division of Reactor Safety and Projects P. Morrill, Chief, Reactor ProjectsSection I D. Acker, Reactor'nspector P. Galon, Reactor Inspector
~ Olson, Project Inspector 2.
Details Hr. Gisclon introduced PG8E personnel and indicated that within the last year a dedicated group had been formed for Probabi listic Risk Assessment (PRA) activities.
He turned the discussion over to Nr. Thierry who provided PGKE's experience with PRA.
The Diablo Canyon PRA was developed as part of the Long Term Seismic Program and was started in 19M.
A consultant was used to develop the PRA, with PG8E involvement,.
Completed in 1988, the PRA examines all accident initiating events and provides core. damage frequences.
The PRA has been reviewed by the NRC and NRC consultants and in June of 1991, the NRC issued the Safety Evaluation Report regarding the PRA.
After Mr. Thierry discussed plant modifications made as a result of the PRA, Mr. Hartin asked about the Auxiliary Saltwater System (ASW) and known difficulties in operating ASW cross connect valves.
In focusing the discussion on a single system, Mr. Hartin asked how closely coupled the PRA is to the plant.
Hr. Shiffer also asked if the PRA is following changes to plant procedures.
Nr. Thierry and Mr. Liu answered that for ASW, a site specific model is used in PRA calculations, and the model is updated to reflect actual plant conditions.
Hr. Gisclon reviewed plans to develop a Diablo Canyon outage risk
.
assessment based on an actual outage schedule.
Nr. Nartin indicated that shutdown risk is an area of focus for the NRC, and this effort will help answer questions about when is the best time to perform equipment
maintenance.
Mr. Gisclon
.stated that a 12 week scheduling program is being utilized to minimize equipment unavailibility.
The 12 week program was implemented for Unit 2 on January 1, 1991, and will be implemented for Unit 1 after the fourth refueling: outage.
Mr. Martin commented that the 12 week scheduling program appears to be a good way to consolidate a
large number of work stems, and the scheduling program can lead to questioning why the preventive maintenance items are scheduled as they are.
Nr. Gisclon also reviewed a preliminary matrix of plant equipment importance.
The matrix could be used in evaluating the increase in risk associated with taking various equipment out-of-service.
PGEE intends to develop the matrix to cover major components in safety related systems.
Once the matrix is developed,
>t could be used to adjust the 12 week maintenance schedule to reduce'he relative risk associated with equipment outages.
Nr. Liu provided information regarding efforts to enhance the PRA.
These efforts include improving the understanding of the model used to develop the PRA, and updating the model to reflect actual plant 'conditions.
As such, every 18 months, a review is performed of plant activities, and-this review is used to update the PRA.
Mr. Morrill asked if Unit 2 activities were reviewed since the PRA model was based on Unit 1.
Mr.
Liu answered that Unit 2 events were also reviewed.
Nr. Perkins asked what were some of the payoffs for having a
PRA. Nr.
Shiffer indicated that the PRA is used in evaluating continued plant operation when equipment problems exist and was used in deciding to procure a sixth diesel generator.
Mr'. Fujimoto said that the PRA is a tool in providing a perspective of relative risk.
Potential use of the PRA includes'developing scenarios for operator training and emergency preparedness drills.
Mr. Gisclon added that they want people in the plant to use information from the PRA but first, training will need to be performed.
A PRA training program is to be developed in 1991.
Nr. Shiffer said that he encouraged use of PRA but is concerned that a
perceived list of limits may develop that conflicts with Technical Specifications.
He also stated a concern that the PRA may be used to second guess decisions.
Mr. Zimmerman said the PRA should be helpful as one of several tools available to provide input to the decision making process.
A key to the practical usefulness of the PRA wi')1 depend on the tr aininq provided to the PG8E staff regarding the expected application and limitations of the PRA.- Nr. Morrill added that while PRA.is not exact, it does provide a basis to quantify nuclear safety and compare alternatives.
In closing the meeting, Mr. Zimmerman stated that AGEE appeared to be on a positive track with PRA, and the NRC supports their effort PRESENTATION TO THE NRC REGION V PG&E's Probabilistic Risk Assessment Program June 28, 1991 8:30-10:30 AGENDA 8:30-8:35 INTRODUCTION 8:35-8:45 PRA ORGANIZATION 8:45-8:55 PGKE's EXPERIENCE WITH PRA 8:55-9:30 CURRENT OBJECTIVES AND ACTIVITIES 9:30-10:30 DISCUSSIONS R LT/P R A01C H T
PRA GROUP ORGANIZATIONAND OBJECTIVES
~
CHANGES Establishment of a Dedicated PRA Group (5 Engineers}
with its Supervisor in NSLE
~
QBJECTI VES Maintain PRA, Complete IPE Apply Risk-Based Concepts in DCPP Operation RLT/PRA02CHT
PG8E's EXPERIENCE WITH PRA
~
Full Scope Level
PRA Long Term Seismic Program Chapter 6 of the LTSP.
Final Report Utilized PLG Inc. as PRA Consultant Significant PG8 E Involvement PGKE Ownership
~
Proven and Comprehensive PRA Detail Review by NRC/BNL SER Issued June 7,
1991 RLT/P RA03CH T
I
PG8E's EXPERIENCE WITH PRA (cont'd)
~
PRA Insights (Plant Improvements}
Diesel Fuel Oil Transfer System Centrifugal Charging Pump Backup Cooling 230kV Switchyard Spare Parts Valve Control Switch Replacement 4.16kV Relay Chatter RLT/P RA04CH T
CURREN T RISK-BASEO PROGRAM OBJECTI VES Shutdown Risk Management Guidance
~
New Applications and Insights
~
EPRI Risk Based Technical Specification Program
~
Living PRA
~
Individual Plant Examination RLT/P RA05CH T
SHUTDOWN RISK MANAGEMENTGUIDANCE J
EPRI 'is Updating its Shutdown PRA of Zion
~
Tailored Collaboration Project with EPRI and VYestinghouse The Project will Use the Zion PRA to Develop a
Diablo-Specific Outage Risk Assessment Based on an Outage Schedule Products Utilizing the Risk Assessment, Guidance will be Developed for:
Outage Planning Management Outage Change. Management Contingency R LT/P R A06CH T
NEW APPLICATIONS ANO INSIGHTS Management Training Integrated Scheduling Program Plant Equipment Importance On-Line Maintenance Sensitivity Studies
.RLT/P RA07CH T
f2 WEEK MATRIXSCHEDULING PROGRAM
~
Objectives Simplify and Standardize.
Scheduling Minimize Equipment Unavailability Eliminate Train Conflicts Provide Advance Scheduling Improve Communications RLT/P RA22GHT
12 WEEK MATRIX SCHEDULING PROGRAM (cont'd)
WEEK TRAIN BUS WED.
UNIT 2 SAT.
A/8 H
D/G 2-2 (M-9A)
RHRP2 (P-38)
AFWP 2 (P-SB)
CCP2 (P-28)
D/G 2-1 (M-9A)
Cspl (P-48)
3.
A SIP1 (P-18)
D/G
(M-9A)
AFWP 3 (P-58)
CCWP1 (P-88)
A/8 NON BUS
A/8 H
SIP2 (P-18)
AFWPl (P-68)
CSP2 (P-48)
D/G 2 (M-9A)
RHRP1 (P-38)
D/G 1 (M-9A)
M-4p 5,6A (AUX. )
SFPP2 (P-11C)
AFWP2 (P-58)
BATP2 (P-148)
CCWP2 (P-&B)
D/G 3 (kl-9A)
CCPL (P-28)
BATP1 (P-148)
AFWP3 (P-58)
A/8 SON
A/8 H
8 G
A F
A/8 NON BUS BUS AFWP1 (P-68)
D/G 2 (M-9A)
9/G 1 (M-9A)
ASWP2 (P-78)
ASWP1 (P-78)
D/G 3 (M-9A)
AFWP1 (P-68)
M-4iSi6A (FHB)
AFWP2 (P-SB)
CHG.
PP
(P 178)
SFPPl ( P-118)
AFWP3 (P-SB)
CCWP3 (P-88)
M-4gSi6A (CNTL)
R LT/P RA27GH T
I
12 WEEK MATRIX SCHEDULING PROGRAM (cont'd)
Scheduling Process
'
Corrective and Preventive Maintenance Activities Interdepartmental Interfaces Work ScopelSchedule Approval
.Work Gro.ups Schedule Modifications Operability of Redundant Equipment RLT/P RA26GH T
PLANT EQUIPMENT IMPORTANCE PRELIMINARY CONFIGURATION RISK RATIO KATRIX COMPONENTS CH PP 1-1 CH PP 1-2 CH HOV 8801A CH HOV 8803A CH HOV 8805A CH HOV 8801B CH HOV 88038 CH KOV 8805B SI PP 1.1 SI PP 1-2 CH PP 1-1 CH PP 1.2 CH HOV 8801A CH HOV 8803A CH HOV 8805A CH IIOV 88018 CH HOV 88038 CH HOV 88058 SI PP 1-1 SI PP 1-2 1.10 1.28 1.18 1.10 1.28 1. 10 1.10 1.28 1.10 1.10 1.10 1.28 1. 10 1.10 1.10 1.28 1.18 1.28 1.28 1.28 1.18 1.28 1.18 1.28 1.28 1.28 1.18 1.18 1.28 1.18 1.28 1.28 1.28 1.18 1.18 1.18 1.20 1.27 1.20
'I.20 1.20 1.27 1.27 1.27 1.09 1.19 1.27 1.19 1.19 1.19 1.27 1.27 1.27 1.19 1.09 RLT/PRA17CHT
SIMPLIFIED SYS TEM SCHEMATIC 8801A 8805A CCP 1-1 (F BUS)
8803A r
I (
I I
I BIT I
I I
88058 8803B SIP 1-1 (F BUS)
RLT/P RA18CH T SIP 1-2 (H BUS)
ON-LINE MAINTENANCESENSITIVITYSTUDIES Increase In Deep core Damage frequency Due to Equipmrnt Unavailability baseline CDf vttcc No System Unavailability i 7.3de-5 /yr vxy 21, 1001 STSIEII O.SX TRAIN UXAVAILAO!LITT Increase In CDF'CPRA VVAVAILABILITT'UPDATE I)
Increace in COF'VAVAILAbILITTAS REPORTED 10 INPO'
II000
~ V-I end U-2 average)
Increase In COF'uxiliary feedvster System'iesel Cenerator System Safety Injection Sys tees Each of 3 trains cxcsvaltsbte O,SX.
COf ~ 7 55e 5 Iyr tech diesel yeneratoc'xcavai table O.SX.
COF ~ 7.C9e-S lyr Each centrlfuyal charylny, Sl, snd RNR pwp train cnavailable O.SX.
COF ~ 7.COe-S /yr 2.3X 1.5X 0.27X Turbine.driven pwp train cxcavatisbte 2.8X.
Notor-driven pwp train casvsllsbte T.CX.
~ 7.06e-S lyr Each diesel generator unavailable T.CX.
~ 7.7e S /yr Centrifugal charging pwp cxcavaltabte 1.3X.
Sl pwp cxcavaitsbte 0.77X.
Vatves cxcsvsitsbte O.OSX.
RRR pwp train cxcavaltsbte 0.83X.
COF > 7A2e.S lyr 7.8X A,AX O.SAX Each of 3 trains cxcsvsltsb'te 1.9X COf ~ 8.01e-S Iyr Each diesel yeneretor vevattsbte 3.$ 'X.
COF ~ d.ide-S lyr Each train unaval 1ebte 1.1$ X.
COF ~ 7.42e-S /yr 8.5X IIX O.SAX Notes:
1.
The percenteye Increase In the besetfne COF fs shcxac.
The baseline CDF vas calculated veiny the OCPRA aedet vith no system cnsvsflsblt Ity. All systese vere assuxed to be available all the time. Ihe chsnye In CDF ls determined by varylny the tnovaltablt Ity of one systaa et ~ time.
The baseline CDF Includes the contributions of ~ll 28 Internal Initiating events, d fire/smohe scenarios, end 3 flood scenarios.
Excluded fraa the baseline COF ere contributions frax eels'ale events, control roax/cable spresdiny roaa fires, end other external Inltlstiny events.
The system cscavaflablllty used In the OCPRA fncludes outayes due to maintenance end testlny.
Cenerie elntenence data ls updated for uss In the DCPRA vlth DCPP-I operatiny experience date (November 108A - Oeceeber 1980)
3..
OCPRA cxatntensnce data ls not directly comparable to INPO cecsvattsbtt lty Indicators.
The OCPRA values only Include maintenance date vhich effects pRA models.
The INpo <<slculstion for failures accuses I/2 of the time since the last test.
Ibpo calculations also doubts ccxxct vhen multiple components are out of service on ~ single train.
A.
The Auxiliary feedvater System contributes the Post to CDF In the DCPRA.
ALL VALVES CIVEN IN TRIS TARLE ARE PRELININART RLT/P RA15GH T
EPRI RISK-BASEO TECHNICAL SPECIFICATION PROGRAM Program Elements Assess Utility Interest Develop Risk-Based Methods Interactive Risk Advisor
~
Motivation
.
Improve Plant Availability and Maintain Safety EPRI Study on Forced Outages (Preliminary)
15%
Due to Tech Spec Compliance 75/0 Addressable by Risk Based Approaches RLT/P RA08GH T
I
EPRI RISK-BASED TECHNICAL SPECIFICATION PROGRAM (conf'd)
Effect of Increased AQTs on Unavailability Change from 72 Hours to 7 Days Maintenance Frequency Unchanged Maintenance Duration Increase Pumps 15%
Heat Exchangers 5%
Valves 6%
Dependent on Maintenance Philosophy
, ~
Effect on Core Damage Risk RLT/P RA09CHT
I,
EPRI RISK-BASED TECHNICAL SPECIFICATION PROGRAM (cont'd)
~
Application to DCPP Assess AOT Extensions for:
Auxiliary Saltwater Component Cooling Water Charging Safety Injection Residual Heat Removal Auxiliary Feedwater Auxiliary Feedwater Shutdown Requirement Auxiliary Saltwater
"Flex Spec" RLT/P RA10GHT
IJ
~
PRA Model Maintenance Activities-Incorporate Design, Procedure, and Technical Specification Changes Maintenance Data Update Component Failure Rate Update Initiating Event Frequency Update Enhancement Activities RLT/PRA11CHT
l
INDIVIDUALPLANT EXAMINATION.
~
Submit Combined Level
and
IPE Reports by April 15, 1992
~
IPE Level 2 Work Level 1-2 Interface Refinement Unit
and 2 Containment Walkdowns Containment Ultimate Strength Analysis Containment Event Tree (CET}
Quantification Uncertainty and Sensitivity Analysis R LT/P8A12CH T
CONCLUSION Proven and Comprehensive PRA
~
Commitment to a Dedicated PRA Organization and Program Integrating Risk-Based Concepts into Maintenance and Outage Scheduling Activities RLT/PRA14GHT
i"
\\