ML16342C355

Summary of 890720 Public Meeting W/Util in Rockville,Md Re Potential License Amend Request to Permit Disabling of One Pressurizer Safety Valve in Event of Leak.List of Attendees & Viewgraphs Encl

ML16342C355
Person / Time
Site:	Diablo Canyon
Issue date:	07/24/1989
From:	Rood H Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8908030284
Download: ML16342C355 (62)

Text

1 DQCKET NOS.:

50-275 and 50-323 July 24, 1989 LICENSEE:

PACIFIC GAS AND ELECTRIC COMPANY (PGELE)

FACILITY:

'IABLO CANYON NUCLEAR POWER PLANT, UNITS 1

AND 2

SUMMARY

OF JULY 20, 1989 PUBLIC MEETING TO DISCUSS POTENTIAL LICENSE AMENDMENT REQUEST (LAR) TO PERMIT DISABLING ONE

'RESSURIZER SAFETY VALVE IN THE EVENT OF A LEAK C

On July 20, 1989 the NRC staff met with PGImE in Rockville, Maryland to discuss the above subject.

Attendees at the meeting are given in Enclosure 1.

The viewgraphs presented by the licensee during the meeting are given in Enclosure 2.

'At the conclusion of the meeting, the NRC staff stated that, based on the material presented at, the meeting, its principal safety concern about the potential LAR was the effect of reduced relief capacity on Anticipated Transients Without SCRAM (ATWS).

The staff recommended that the licensee provide a more detailed development of the Probabilistic Risk Analysis (PRA) covering transients in which reduced pressure relief capacity affects the outcome of the event.

original signed by

Enclosures:

1.

Meeting Attendees 2.

Viewgraphs Presented by Licensee cc: w/enclosures

- see next page Harry Rood, Senior Project Manager Project Directorate V

Division of Reactor Projects - III, IV, V and Special Projects DISTRIBUTION

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DOCKET NOS.:

50-275 and 50-323 UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 July 24, 1989 LICENSEE:

FACILITY:

SUBJECT:

PACIFIC GAS AND ELECTRIC COMPANY (PGSE)

DIABLO CANYON NUCLEAR POWER PLANT, UNITS I AND 2

SUMMARY

OF JULY 20, 1989 PUBLIC MEETING TO DISCUSS POTENTIAL LICENSE AMENDMENT REQUEST (LAR) TO PERMIT DISABLING ONE PRESSURIZER SAFETY VALVE IN THE EVENT OF A LEAK On July 20, 1989 the NRC staff met with PGEE in Rockville, Maryland to discuss the above subject.

Attendees at the meeting are given in Enclosure 1.'he viewgraphs presented by the licensee during the meeting are given in Enclosure 2.

At the conclusion of the meeting, the NRC staff stated that, based on the material presented at the meeting, its principal safety concern about the potential LAR was the effect of reduced relief capacity on Anticipated Transients Without SCRAM (ATWS).

The staff recommended that the licensee provide a more detailed development of the Probabi listic Risk Analysis (PRA). covering transients in which reduced pressure relief capacity affects the outcome of the event.

Enclosures:

1.'eeting Attendees 2.

- Viewgraphs Presented by Licensee cc: w/enclosures - see next page Harry Rood, Senior Project Manager Project Directorate V

Division of Reactor Projects - III, IV, V and Special Projects

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, Mr.d. D. Shiffer Pacific Gas and Electric Company Diablo Canyon CC'ichard F. Locke, Esq.

Pacific Gas 5 Electric Company Post Office Box 7442 San Francisco, California 94120 Ms. Sandra A. Silver 660 Granite Creek Road Santa Cruz, California 95065 Mr. Peter H..Kaufman Deputy Attorney General State of California 110 West A Street, Suite 700 San Diego, California 92101 Managing Editor The Count Tele ram Tribune P.

ox ll C airman San Luis Obispo, California 93406 Ms. Nancy Culver 192 Luneta Street San Luis Obispo, California 93401 Regional Administrator, Region V

U.S. Nuclear Regulatory Commission 1450 Maria Lane Suite 210 Walnut Cree k, Ca 1 iforni a 94596 NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P. 0.

Box 369 Avila Beach, California 93424 Bruce Norton, Esq.

c/o Richard F. Locke, Esq.

Pacific Gas and Electric Company Post Office Box 7442 San Francisco; California 94120 Dr. R. B. Ferguson Sierra Club - Santa Lucia Chapter Rocky Canyon Star Route Creston, California 93432 San Luis Obispo County Board of Supervisors Room 270 County Government Center San Luis Obispo, California 93408 Michael M. Strumwasser, Esq.

Special Assistant Attorney General State of California Department of Justice 3580 Wilshire Boulevard, Room 800 Los Angeles, California 90010 Dr. Gerard C.

Wong,- Chief Radiological Materials Control Section State Department of Health Services 714 P Street, Office Building 88 Sacramento, California 95814

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ENCLOSURE 1

ATTENDEES Public Meeting on Diablo Canyon Pressurizer Safety Valves Thursday, July 20, 1989 Steve Chesnut John tI.

G iscion Gary Hammer Wayne Hodges R. C. Jones Barklay S.

Lew Edward Petrosky Harry Rood Anthony Sicari Raymond Thierry J.

E. Tomkins Al Wooten George Wu ORGANIZATION PG&E PG&E NRC/DEST/EMEB NRC/DEST/SRXB NRC/DEST/SRXB PG&E Westinghouse (PG&E)

NRC/DRSP/PDV Westinghouse (PG&E)

PG&E

'G&E Westinghouse (PG&E)

PG&E

ENCLOSURE 2 VIEMGRAPHS PRESENTED BY PG&E Public Meeting on Diablo Canyon Pressurizer Safety Valves Thursday, July 20, 1989 f4

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PG>E -

NRC MEETING PRESSURIZER SAFETY VALVES JULY 20,

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AGE DA I.

PURPOSE (B. S.

LEW)

II.

PGRE AND INDUSTRY EXPERIENCE WITH LEAKING PRESSURIZER SAFETY VALVES (J.

M. GISCLON)

III. PGE E PROGRAM (J.

M. GISCLON)

IV.

OVERVIEW OF EVALUATION (J.

M.

GISCLON /

L. A.

WOOTEN)

V.

PROPOSED LAR TO DISABLE ONE PRESSURIZER SAFETY VALVE (J.

M. GISCLON)

IV.

DISCUSSION (ALL)

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PURPOSE/OBJECTIVES PRESENT STATUS OF PGRE'S ACTIONS REVIEM PGRE'S PROGRAM REVIEW EVALUATION OBTAIN STAFF COMMENTS AND FEEDBACK DISCUSS STAFF COMMENTS AND FEEDBACK PG8E's APPROACH TOWARDS DEALlNG WITH A LEAKING PRESSURIZER SAFETY YALYE SUBM1T LAR TO PROYIDE FLEXIBILITY FOR DISABLING YALVE

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DCPP PRESSURIZER SAFETY VALVE SCHEMATIC PCV 4N Preaaurlzer Relict Tank 8

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Vent f6C6V~ 8OOOB M

4010 C

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PCV 8000C 456 PRESSURIZER

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GENERAL HISTORY OF PRESSURIZER SAFETY VALVES EARLY EXPERIENCE INDICATED MANY LEAKING VALVES DUE TO HYDROGEN/STEAN CUTTING LOOP SEALS WERE INCORPORATED INTO DESIGN LOOP SEAL MUST BE.MAINTAINED AT SUFFICIENT TEMPERATURE TO PREVENT EXCESSIVE TAILPIPE LOADING DUE TO WATER PRESSURE DURING DISCHARGE HAVE HAD. DIFFICULTY IN SETTING SAFETY VALVES W NOW HAS BEAUMONT FACILITY WITH LIVE STEAM AND LOOP SEAL LOOKING AT WAYS TO RESOLVE PROBLEM BETTER SEAT MATERIALS/NO LOOP SEAL DIFFERENT TYPE OF VALVE (FRENCH)

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PGRE EXPERIENCE MITH PRESSURIZER SAFETY VALVE LEAKS PREVIOUS MINOR LEAKS IN 1986, 1987 MARCH 1989, UNIT 2 VALVE LEAKING BETWEEN 0 AND 0.2

GPN, AVERAGE BRIEF INTERVALS OF BURPING CALCULATIONS SHOWED LOOP SEAL PROBABLY NOT PRESENT BEST ESTIMATE CALCULATIONS WITH LOWER VALVE LIFT POINT SHOWED VALVE WAS UNLIKELY TO BE CHALLENGED ANALYSES PERFORMED WITH ONE VALVE DISABLED SHOWED ACCEPTABLE RESULTS FOR FSAR TRANSIENTS QN APRIL 8, TOOK UNIT DOWN FOR ONE MEEK TO REPAIR VALVE

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ITEMS OF CONCERN DURING MARCH 1989 LEAKAGE WERE:

HAVING POTENTIAL FOR VALVE LIFTING & NOT RES EATING INCREASING LEAK RATE TO WHERE THE PRESSURIZER RELIEF TANK COULD NOT BE MANAGED

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INDUSTRY EXPERIENCE WITH LEAKING PRESSURIZER SAFETY VALVES VIRGIL SUMMER (3 LOOP W).

MAY 28, 1989.

LEAKING PRESSURIZER SAFETY VALVE LIFTED TO 50~o OPEN AT POWER.

THE REACTOR WAS MANUALLY TRIPPED AND AN SI MAS BARELY AVOIDED.

DIABLO CANYO (4

LOOP W).

MARCH 1989.

PRESSURIZER SAFETY VALVE LEAKING WITH BRIEF INTERVALS OF BURPING.

PLANT SHUT DOWN TO REPLACE VALVE.

PRESSURIZER SAFETY VALVE LEAKAGE OBSERVED IN PREVIOUS CYCLES.

ST.

LUCIE (CE).

RAN WITH BURPING PRESSURIZER SAFETY VALVES DURING THREE DIFFERENT FUEL CYCLES.

PRT RUPTURE DISK BLEW.

SALEM 2 (4 LOOP W).

PRESSURIZER SAFETY VALVE STARTED LEAKING MHILE AT POWER.

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INDUSTRY EXPERIENCE (coNT.)

SEQUOYAH (4 LOOP M).

SLOM, STEADY LEAKAGE FROM A PRESSURIZER SAFETY VALVE.

SA ONOFRE U IT 1 (2 LOOP M).

EXPEarENCED LEAKS DURING OPERATION AND MHEN RETURNING TO POMER AFTER AN OUTAGE.

LEAKS MERE LESS THAN 1 GPM.

ARKANSAS NUCLEAR 0 E UNIT 2 (CE).

SEEPING AND BURPING OF PRESSURIZER SAFETY VALVES.

ONE SETPOINT HAD DRIFTED 100 PSI LOM.

EIGHT OTHER PLANTS HAVE REPORTED LEAKAGE.

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PG&E's APPROACH ROOT CAUSE ANALYSIS IMPROVED TESTING TECHNIQUES DETERMINISTIC ANALYSIS IMPROVEMENTS VALVE MATERIALS /DESIGN TECH SPEC FLEXIBILITY REDUCED VALVE NOZZLE LOADS 10

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ROOT CAUSE ANALYSIS EXAMINED AND TESTED VALVE 8010A VISIBLE EVIDENCE OF LEAK PATH ON SEAT POSSIBLE ROOT CAUSES FOR LEAKAGE FOREIGN MATERIAL. ON SEAT NOZZLE LOADS HYDROGEN BUBBLE

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IMPROVED TESTING TECHNIQUES o

POWER ASSISTED TESTING 0

BEAUMONT FACILITY LIVE STEAM IDENTICAL GEOMETRY, INCLUDING LOOP SEAL IDENTICAL VALVE ENVIRONMENT

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SAFETY EVALUATION FSAR ACCIDENTS HAVE BEEN EVALUATED BY WESTINGHOUSE TO SHOW THAT THERE IS NO SIGNIFICANT HAZARDS CONCERN ASSOCIATED WITH DISABLING ONE PRESSURIZER SAFETY VALVE.

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LOSS OF LOAD RESULTS (PEAK PRESSURE, PSIA) 3 VALVES 1'OLERANCE 3 VALVES 3:

TOLERANCE 2

VALVES 3:

TOLERANCE 2553 2630 2654 2549 2621 264O

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FSAR ACCIDENTS THE LOSS OF LOAD ACCIDENT MITH 3'0 SETPOINT TOLERANCE AND ONE DISABLED PRESSURIZER SAFETY VALVE HAS BEEN ANALYZED BY WESTINGHOUSE AND PG&E.

THE PEAK PRESSURE IS BELOW 110'F DESIGN PRESSURE.

A SAFETY EVALUATION HAS BEEN PERFORMED BY WESTINGHOUSE TO ASSESS THE IMPACT OF DISABLING ONE PRESSURIZER SAFETY VALVE ON ALL FSAR ACCIDENTS.

WESTINGHOUSE CONCLUDED THAT THE OPERATION OF DIABLO CANYON WITH TMO OF THE THREE PRESSURIZER SAFETY VALVES OPERAT10NAL IS ACCEPTABLE AND THE CONCLUSIONS OF THE FSAR REMAIN VALID.

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WESTINGHOUSE SAFETY EVALUATION NON-LOCA ACCIDENTS ARE PRIMARY ACCIDENTS ADDRESSED LOSS OF LOAD ACCIDENT IS THE PRIMARY ACCIDENT INVESTIGATED BECAUSE IT GENERATES PEAK PRESSURES FOR THE PRIMARY SYSTEM A)

ONLY THE NQ-PRESSURE CONTROL CASES ARE OF INTEREST SINCE THEY GENERATE THE MAXIMUM PRESSURE B) MIN AND MAX REACTIVITY FEEDBACK ARE RUN CASES FOR LOSS OF LOAD REANALYZED A)

EXAMINED 2 VERSUS 3 VALVES OPERABLE 8)

INCLUDED STUDY OF LIFT TOLERANCE OF. UP TO 3'0

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. OTHER NON-LOCA ACCIDENTS EXAMINED EVENTS EVALUATED POTENTIALLY IMPACTED ROD WITHDRAWAL AT POWER LOSS OF NORMAL FEED

- STATION BLACKOUT

- FEEDLINE BREAK LOCKED ROTOR ROD EJECTION STEAM BREAK INSIDElOUTSIDE CONTAINMENT EVENTS NOT SIGNIFICANTLY IMPACTED ROD WITHDRAWAL FROM SUBCRITICAL ROD MISOPERATION BORON DILUTION

- PARTIALlCOMPLETE LOSS OF FLOW

- STARTUP OF INACTIVE LOOP FEED MALFUNCTION

- EXCESSIVE LOAD INCREASE RCS DEPRESSURIZATION

- STEAM LINE DEPRESSURIZATION

- SPURIOUS SI

- STEAM LINE BREAK

- SINGLE ROD WITHDRAWAL

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EVENTS NOT IMPACTED (DEPRESSURIZATION)

GTR NOT IMPACTED (PRESSURE BELOW SETPOI

SUMMARY

DIABLO CANYON UNIT 1 AND 2 FSAR CHAPTER 15 CONCLUSIONS REMAIN VALID WITH 2 PRESSURIZER SAFETY VALVES OPERABLE

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PROPOSED TECHNICAL SPECIFICATION CHANGE ACTION STATEME T WITH A MAXIMUM ONE PRESSURIZER CODE SAFETY YALVE INOPERABLE BUT INCAPABLE OF OPENING, RESTORE THE INOPERABLE VALYE TO OPERABLE STATUS AT THE NEXT COLD SHUTDOWN OF SUFFICIENT DURATION TO NAKE THE REPAIR.

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RE'ACTOR 'COOLANT SYSTEM OPERATING LIMITING CONDITION FOR OPERATION 3.4.2.2 All pressurizer Code safety valves shall be OPERABLE with a lift setting of 2485 psig a IX.*

APPLICABILITY:

MODES 1, 2 and 3.

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With one pressurizer Code safety valve inoperabl, either restore the inoperable valve to OPERABLE status within 15 minutes or be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in at least HOT SHUTDOWN within the

. following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

ACTION:

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4. 4. 2.2 No additional requirements other than those required by Specifica-tion.4.0.5.

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The provisio'ns of Specification 3.0.4 may be suspended for up to 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> per valve for entry into and during operations in NODE 3 for the purpose of setting the pressurizer Code safety valves under ambient (hot) conditions provid'.d a preliminary cold setting was made prior to heatup.

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"The lift setting pressure shall correspond to ambient conditions of the valve at nominal operating temperature and pressure.

DIABLO CANYON - UNITS 1 8

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OPTIONS FOR DISABLING A WEEPING PRESSURIZER SAFETY VALVE THE FOLLOWING APPROACH HAS POTENTIAL MERIT DISABLE VALVE EARLY ON WHEN EVIDENCE OF WEEPING OCCURS THEN ASSESS WHETHER TO CONTINUE OPERATION OR SHUTDOWN/COOLDOWN WILL STABILIZE SITUATION PREVENT INADVERTANT ACTUATION AT LOW PRESSURE I~

MAY ALLOW REFORMATION OF LOOP SEAL, COULD THEN REMOVE GAG o

LIMITED DURATION, PGEE WILL REPAIR OR REPLACE AT THE NEXT OUTAGE OF SUFFICIENT DURATION

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0 BENEFITS OF DISABLING A LEAKING SAFETY VALVE PREVENT INADVERTENT ACTUATION AVOID ADDITIONAL HEATUPlCOOLDOWN CYCLE ON SYSTEM POSSIBLE ADDITIONAL BENEFITS REDUCE LEAKAGE ALLOW REFORMING OF LOOP SEAL 22

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IMPLEMENTATION YALYES DESIGNED FOR DISABLING DISABLING A RELATIYELY SIMPLE OPERATION CAN BE DONE AT POWER 23

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IMPLEMENTATION CAP PLUG VALVE NOT GAGGED VALVE STEM GAG SCREW VALVE GAGGED 24 t,p

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MANPOWER~DOSE RATE IMPLICATIONS TOTAL IMPLEMENTATION TAKES - 1.5 MANHOURS EFFORT TOTAL ESTIMATED MAN REM = 0.1 0

THE MORK CAN BE ACCOMPLISHED AT POMER 0

THERE IS NO PROBLEM ASSOCIATED WITH IMPLEMENTATION 25

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SUMMARY

PGKE HAS.ON-GOING PROGRAM TO CORRECT SAFETY VALVE PROBLEMS INCLUDING LEAKAGE AND SETPOINT DRIFT DETERMINISTIC ANALYSIS SUPPORTS OPERATION WITH ONLY TMO OF THREE SAFETY VALVES.

IT IS DESIRABLE TO HAVE THE CAPABILITY OF DISABLING ONE PRESSURIZER SAFETY VALVE TO PREVENT INADVERTENT ACTUATION.

DISABLING IS A SIMPLE OPERATION THAT CAN BE DONE AT POMER.

ONLY VALVES WHICH MERE WEEPING EXCESSIVELY WOULD BE DISABLED.

LIMITED DURATION, REPAIR/REPLACE LEAKING VALVE AT NEXT OUTAGE OF SUFFICIENT LENGTH.

PGSE MILL CONTINUE TO PROACTIVELY RESOLVE THIS ISSUE NEM VALVE MATERIALS/DESIGNS IMPROVED TESTING ANALYSIS

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