ML20044A165

Summary of Operating Reactors Events Meeting 90-17 on 900620 Re Selected Events That Occurred Since Last Briefing on 900613

ML20044A165
Person / Time
Site:	Diablo Canyon, Maine Yankee
Issue date:	06/21/1990
From:	Chaffee A Office of Nuclear Reactor Regulation
To:	Rossi C Office of Nuclear Reactor Regulation
References
OREM-90-017, OREM-90-17, NUDOCS 9006280152
Download: ML20044A165 (17)

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June 21, 1990

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MEMORANDUM FOR:

Charles E. Rossi, Director Division of Operationel Events Assessment FROM:

Alfred E. Chaffee, Acting Chief J

L Events Assessment Branch Division of Operational Events Assessment SUBJECTr THE OPERATING REACTORS EVENTS MEETING June 20, 1990 - MEETING 90-17 On' June 20, 1990, weconducted-anOperatingReactorsEventsmeeting(9017) to inform senior managers from NRR, ACRS, RES, Commission staff, and regional offices of selected events that occurred since our last briefing on June 13, 1990. lists the attendees. presents the significant elements of the discussed events. contains reactor scram statistics for the week ending 06/17/90.

I

• tabulates one significant event ~which was identified for input into the NRC performance indicator program.

Original Signed by Alfred E. Chaffee, Acting Chief Events Assessment Br'ach Division of Opere.onal Events Assessment

Enclosures:

As stated cc w/ Encl.:

See Next Page hf:entrab F11e M

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June 21, 1990 j

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MEMORANDUM FOR:

Charles E. Rossi, Directre U

Division of Operational Events Assessment FROM:

Alfred.E. Chaffee, Acting Chief Events Assessrhent Branch Division of Operational Events. Assessment

SUBJECT:

THE OPERATING REACTORS' EVENTS MEETING June 20, 1990'- MEETING 90-17 L

On June 20, 1990, we conducted an Operating Reactors Events meeting (90-17)

Y

'to inform senior managers.from NRR, ACRS, RES, Comission staff, and regional-offices cf selected events that occurred since our last briefing on June 13, 1990. lists the attendees. presents the

~ q significant elements of the discussed events

~

,, contains reactor scram statisti;s for the week-ending 06/17/90. tabulates.one significant even; which was' identified for input into the NRC' performance indicator progra a.

i Alfred E. Chaffee,. Acting Chief l

Events Assessment Branch Division of Operational Events Assessment

Enclosures:

As. stated-

.-y cc w/ Encl.:

See Next Page' 7

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ENCLOSURE 1 LIST OF ATTENDEES OPERATING REACTORS. EVENTS. BRIEFING-(90-17)

June 20, 1990 b-NAME ORGANIZATION NAME ORGANIZATION F. Miraglia NRR/DONRR R. Jor.es NRR/SRXB B. Grimes NRR/DRIS P. Boehnert ACRS N. Campbell.

NRR/00EA L. Norrholm OCM/KC.

W. Jensen-NRR/DOEA J. Larkins NRR/DRSP G..Vissing.

NRR/PD2-4 W. Wu NRR/SRXB

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J. Norris NRR/PD2-2 D. Fieno NRR/SRXB E. Leeds :

NRR/DRP L. Phillips NRR/SRXB l

N. Fields NRR/D0EA W. Minners RES/DSIR S. Varga NRR/DRP P. Baranowsky NRR/DOEA A. Chaffee-NRR/D0EA D. Crutchfield NRR/DRSP J. Tatum NRR/DRSP M. Snodderly-NRR/DRIS S. Long.

NRR/DREP S. Sanders NRR/DRIS

- D. Mcdonald

'NRR/DRP B. Boger NRR/DRP M. Slosson NRR/DRP A. Thadani NRR/ DST t

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ENCLOSURE 2

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OPERATING REACTORS EVENTS BRIEFING 90-17

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EVENTS ASSESSME.NT BRANCH LOCATION:

12B-11, WHITE FLINT-1 WEDNESDAY, JUNE 20, 1990, 11:00 A.M.

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i MAINE: YANKEE COMEUSTION ENGINEERING' CONTROL ELEMENT ASSEMBLY FAILURE' DIABLO: CANYON UNIT 1 ONE HUNDRED PERCENT LOAll ji REJECTION WITH UNANTICIPATED-4 REACTOR TRIP I

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90-17 q

MAINE YANKEE

.CO'MBILSTION ENGINEERING CONTROL ELEMENT ASSEMBLY FAILUR_E JUNE 7, 1990 l

PROBLEM FAILURE OF OLDER COMBUSTION ENGINEERING (CE) DESIGN CONTROL ELEMENT l

' ASSEMBLY (CEA)-PRIOR TO PROJECTED END-OF-LIFE a

CAUSE THE-LICENSEE SUSPECTS STRAIN IN CENTER " FINGER" DUE TO BORON l

CARBIDE (B4C) SWELLING, i

' SAFETY SIGNIFICANCE CEA FAILURES COULD RESULT IN SINGLE / MULTIPLE STUCK RODS WHICH COULD LEAD TO LOCAllZED CRITICALITY AFTER REACTOR TRIP (ANTICIPATED TRIP WITHOUT SCRAM)..

l BACKGROUND o

OLDER.CE CEA DESIGN WAS'A 5-FINGER, SPIDER-DESIGN MADE OF l

INCONEL-(SEE FIGURE A),

j 4 CORNER FINGERS WERE FILLED WITH B4C PELLETS EXCEPT FOR LOWEST 8 INCHES, WHICH WERE FILLED WITH SILVER-INDIUM-CADMIUM i

TO PREVENT SWELLING-AT LOWER TIP.

SINGLE CENTER FINGER WAS FILLED WITil-B4C-PELLETS TO THE LOWER-l TIP, AND WAS EQUIPPED WITH A SPRING-LOADED SH0CK ABSOR3ER j

- AT THE TOP, o

IN THE EARLY'1980fS, CE RECOGNIZED THE CONCERN FOR SWELLING IN THE-CENTER FINGER OF THE CEA, o

CEA. CRACKS WERE FOUND AT CALVEP.T CLIFFS UNIT 1 D'URING THEIR 1987 1

f REFUELING, o

CUPRENT CEA DESIGN INCLUDES SILVER-lNDIUM-CADMlUM IN THE LOWER 8 INCHES OF THt! CENTER FINGER AS WELL AS IN THE 4 CORNER FINGERS, i

CONTACT:

A. P, YOUNG SIGEVENT:

YES

REFERENCE:

MORNING REPORT 06/13/90 AND 10 CFR 50.72# 18708 i

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M RNE YANKEE

- 2' -

90-17 9

DISCUSSION 1

0 ' DESIGN-LIFE FOR OLDER DESIGN IS 13 YEARS, c

DURING SCHEDULED REFUELING OUTAGE. MAINE YANKEE DISCOVERED FAILED CEA BEFORE CEA REACHED ITS.'0-YEAR LIFE (END CAP WAS MISSING),

o CURRENT ACCEPTANCE CRITERIA 0F 1,2% STRAIN (ALLOWABLE RADIAL DEFORMATION OF CEA's) IS ALSO IN 0UESTION, o

DURING FOLLOWUP EDDY CURRENT-TESTING INVESTICATIONS, MAINE. YANKEE DISCOVERED 5 ADDITIONhl.CEA's CURRENTLY IN USE WITH POTENTIAL CENTER FINGER CRt.CKS, o

LICENSEE HAS ALSO DISCOVERED AXl AL CRACKS ON L! CENTER FINGERS ON 15 CEA's THAT WERE REMOVED LURING THIS OUTAGE -- 2 HAD MISSING END CAPS, o

MOST OF THE OLDER CE PLANTS HAVE PHASED-0VT THIS OLDER DESIGN (SEE TABLE 1),

FOLLOWUP o

LICENSEE ALERTED INDUSTRY OF POTENTIAL PROBLEM WITH OLDER CE DESIGN CEA THROUGH INP0 NUCLEAR NETWORK, o

LICENSEE IS CONDUCTING HISTORICAL INVESTIGATION OF EXPOSURE OF THE OTHER 23 CEA'S OF THIS OLDER DESIGN, o

22-OF THE OLDER DESIGN CEA'S-WILL BE REPLACED dlTH CEA'S OF-

.THE NEW DESIGN, 1 WILL BE REPLACED WITH A NEW CEA 0F THE OLD DESIGN (PLACED IN-A NON-TRIPPABLE LOCATION),

o THE REGION AND'NRR (INCLUDING SRXB AND EMCB) ARE' DISCUSSING WITH:THE LICENSEE AND CE THE APPROPRIATENESS OF THElR ROOT CAUSE ACTIVITIES AND PROPOSED CORRECTIVE ACTIONS, o

NRR HASLISSUED-QUESTIONS TO LICENSEES WHO MAY BE AFFECTED FOR RESPONSE BY COB, WEDNESDAY, JUNE 20, 1990, o

A MEETING IS SCHEDULED FOR MONDAY, JUNE 25, 1990, TO DISCUSS THE LICENSEE'S ONGOING. INVESTIGATIONS, ROOT CAUSE ANALYSIS, L

ANY TEST RESULTS, AND'THE ADEQUACY OF THIS OLDER CE DESIGN AS THE CEA'S APPROACH END-OF-LIFE, O

A CE REGULATORY PESPONSE GROUP MEETING WITH NRR IS SCHEDULED FOR MONDAY, JUNE 25, 1990, o

OEAB IS PREPARING AN INFORMATION NOTICE.

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~ *l, MAINE YANKEE.

_90 17 COMBUSTION ENGINEERING CONTROL ELEMENT ASSEMBLY (Older Design) p p

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1 TABLE 1 1

PREllMINARY.lNFORMAT10N ON GENERIC APPLICABILIT( OF-OLDER-DESIGNED COMBUSTION ENGINEERING (CE) CONTROL ELEMl'.NT ASSEMBLIES AT OTHER CE PLANTS NUMBER OF CEAs

[.g FROM OLDER DESIGN DATE 0lF-SCHEDULED

)

' -PLANT YEAR LICENSED IN ACTIVE CORE REPLACEMENT PAllSADES-71 0

i MAINE 1 YANKEE-72 23

-6/90 REFUELING

.Fr.^ CALHOUN 73 2

NONE SCHEDULED t

CALVERT CLIFFS 1 74 0

y

. MILLSTONE 2 75

13 9/90 REFUELING m

1mST. LUCIE 1 76 17 11/91. REFUELING LCALVERT CLIFFS 2 76 68 FALL 92 8 94 REFUELINGS j

ANO 2 78 0

4 ; ST. LUCIE 2 83 0

WATERFORD 85 0

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[L' 90-17 N

DIABLO CANYON UNIT 1 4

ONE HUNDRED PERCENT LOAD REJECTION WITH UNANT!CIPATED l1-

-REACTOR TRIP JUNE 14, 1990

[

PROBLEM 1100 PERCENT LOAD REJECTION AND REACTOR TRIP RESULTING IN LOSS OF 1

g FORCED RCS CIRCULATION FOR A PERIOD OF EIGHT MINUTES, l

CAUSE

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AN'0FFSITE FIRE INITIATED THE AUTOMATIC ISOLATION OF MAIN GENERATOR-OUTPUT FOLLOWED BY A REACTOR TRIP AND SUBSEQUENT TURBINE TRIP, SAFETY SIGNIFICANCE Jo OFFSITE EVENT INITIATED A REACTOR TRANSIENT, l

o' POTENTIAL UNREVIEWED SAFETY ISSUE 1F THE EVENT IS NOT B0UNDED

.BY FSAR TRANSIENT ANALYSIS,

. DISCUSSION o' ON JUNE-14, 1990 AT 3:55 P.M. PDT, A 100 PERCENT LOAD REJECTION q

D AE A

ON Ut T j

o PRIOR TO THE EVENT,'ONE OF TWO MAIN GENERATOR-OUTPUT BREAKERS WAS OUT OF SERVICE FOR MAINTENANCE, o

AN 0FFSITE FIRE CAUSED THE OPENING OF THE SECOND OUTPUT BREAKER, i

i INTERRUPTING THE ELECTRICAL OUTPUT.FROM THE UNIT TO THE 500KV SWITCHYARD,

o A' TURBINE OVERSPEED CONDITION OCCURRED RESULTING IN FREQUENCY INCREASING TO 65 HZ (BELOW THE 66-HZ TURBINE OVERSPEED TRIP

g

-SETPOINT),

Jo THE' INCREASED FREQUENCY CAUSED THE RCPS TO SPEED UP AND INCREASE COLD LEG FLOW INTO THE CORE RESULTING IN A REDUCTION IN AVERAGE CORE TEMPERATURE, 2-e CONTACT:

tilCK FIELDS SIGEVENT:

TBD

REFERENCES:

10 CFR 50,72# 18712, MORNING REPORTS 06/14/90 & 06/19/90 t

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/ DfABLO. CANYON

_ 90-17

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DISCUSSION (CONTINUED) o THE POSITIVE REACTIVITY ADDITION RESULTING FROM THE C00LDOWN CAllSED THE REACTOR TO TRIP ON HIGH POSITIVE NEUTRON FLUX RATE, THE TRIP OCCURRED 1,5 SECONDS AFTER THE LOAD REJECTION, THE TURBINE TRIP FOLLOWED THE REACTOR TRIP, i

o THE UNIT IS DESIGNED TO SUSTAIN A 100 PEPCENT LOAD REJECTION WITHOUT THE NEED FOR A REACTOR TRIP, THEREFORE, AS DESIGNED, AN AUTOMATIC TRANSFER OF THE 12KV BUSES TO THE ALTERNATE l

0FFSITE POWER SUPPLY DID NOT OCCUR.-

0 ALL REACTOR COOLANT PUMPS TRIPPED ON UNDERFREQUENCY AS THE MAIN GENERATOR C0ASTED TO DOWN, THE UNIT SUCCESSFULLY ENTERED NATURAL CIRCULATION COOLING,

-o A'" MANUAL TRIP" WAS INITIATED WHICH AMONG OTHER THINGS TRANSFERS ELECTRICAL POWER FROM THE AUX TRANSFORMER TO STARTUP/ STANDBY

-TRANSFORMER, ALL FOUR REACTOR COOLANT PUMPS WERE STARTED; HOWEVER, j

BECAUSE-0F ITS CONTROL LOGIC, THE CIRCULATING WATER PUMPS DID NOT RESPOND TO AN AUTO RECLOSE-SIGNAL o

ALL OF THE LOW PRESSURE TURBINE RUPTURE DISKS WERE BLOWN OUT IN.

1 SPITE OF OPERATORS' ATTEMPTS TO MANUALLY BREAK CONDENSEP VACUUM, j

(MSR STOP'AND INTERCEPT VALVES CLOSED AS PER DESIGN BUT APPARENT l

-SEAT LEAKAGE OVERPRESSURIZED THE TURBINE,)

1 o' 0NE 0F THREE EMERGENCY DIESEL GENERATORS STARTED ON BUS UNDERVOLTAGE BUT DID NOT LOAD DUE TO THE TRANSFER TO THE ALTERNATE i

0FFSITE SOURCE, i

FOLLOWUP o

LICENSEE HAS CONFERRED WITH WESTINGHOUSE REGARDING THE SIGNIFICANCE OF THIS EVENT AND THE FEASIBILITY OF IMMEDIATE i

PESTART, NRR REQUESTED LICENSEE T0 DETERMINE WHETHER THIS EVENT l

IS BOUNDED BY THE FSAR TRANSIENT ANALYSES, o

FOLLOWING REPLACEMENT OF SEVERAL CONDENSER TUBE PLUGS WHICH WERE DISLODGED.AS A RESULT OF THE TRANSIENT AND THE CLEAN-UP 0F SALTWATER IN-LEAKAGE, UNIT RESTARTED WAS ATTEMPTED ON JUNE 17, 1990, BUT DUE TO

,3 i:

EXCESSIVE VIBRATION AND LUBE OlL LEAKS ON MAIN FEEDWATER PUMP (MFWP) i NUMBER 11, THE RESTART EFFORT WAS UNSUCCESSFUL, AT THE TIME, MFWP NUMBER 12 DISCHARGE CHECK VALVE WAS ALSO FOUND TO BE STUCK

OPEN,

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1 0'ABLO-CANYON UNIT 1 90-17 u

4 f_0R0WUP (CONTihuED) 0 o

AS OF JUNE 19, 1990, UNIT 1 WAS ESCALATING TO 50 POWER ON MFWP NUMBER 12, MFWP NUMBER-11 TURBINE WAS FOUND TO HAVE A FAILED INBOARD SHAFT BEARING AND THE-TURBINE CASING BUTTERFLY SUPPORT BOLTS (TURNING GEAR) WERE SHEARED OFF.

-(r THE-REGION IS FOLLOWING LICENSEE'S ACTIONS, o

REACTOR SYSTEMS BRANCH WILL REVIEW THE LICENSEE'S DOCUMENTATION

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JUSTIFYING THEIR CONCLUSION THAT THE EVENT: IS B0UNDED BY THE FSAR TRANSIENT ANALYSES, i

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- II, COMPARISON OF WEEKLY STATISTICS WITH INDUSTRY AVERAGES r

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SCRAMS FOR WFRK ENDIKI' 06/17/90 SCRAM CAUSE-POWER HUMBER 1990'

-1989 1988

-1987 1986 OF.

WEEKLY WEEKLY WEEKLY WEEKLY WEEKLY

-i SCRAMS (5')--

AVERAGE AVERAGE - AVERAGE AVERAGE AVEPAGE YTD (3)(4)

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@* KHER >15*4 liQUIP.'RELATED. >15%

3 3.1 2.9

-3.1 3.9 4.3

, ! PERS. ! RELATED(6) >15%

0 0.5 1.0 1.0 1.3 1.8 i

,CfrHER(7)_

>15%

0 0,0 0.1 0.5 1.2 0'. 4

- ** Subtotal **

3 3.6 4.0 4.6 6.4 6.5

.'r* POWER <15%

BQUIP. RELATED

<15%

1 0.5 0.4 0.5 1.2 1.4

'l C PERS. RELATED-

<15%

0 0.2 0.3 0.3 0.6 0.8 OIRER

<15%

0 0.0 0.7 0.1 0.3 0.2

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• • Subtotal **

1 0.7 1.4 0.9 2.1 2.4

• • • Total ***

O 4

4.3 5.4' 5.5 8.5 8.9 i

1 MANUAL VS AITIO SCRAMS TYPE NUMBER 1990 1989 1988 1987 1986 a

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OF WEEKLY WEEKLY WEEKLY WEEKLY WEEKLY SCRAMS AVERAGE AVERAGE AVERAGE AVERAGE AVERAGE YTD-

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.MANUALiSCRAMS:.

0 1,1 0.9-1.0 1.4 1.0 t

' AUTOMATIC SCRAMS 4

3.1 3.8 4.5 7.0

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NOTES' 1.

PLANT SPECIFIC DATA BASED ON INITIAL REVIEW 0F 50.72 REPORTS FOR THE WEEK OF INTEREST.

PERIOD IS MIDNIGHT SUNDAY THROUGH MIDNIGHT SUNDAY.

SCRAMS ARE DEFINED AS REACTOR PROTECTIVE ACTUATIONS WHICH RESULT-IN R0D MOTION, AND EXCLUDE PLANNED TESTS OR SCRAMS AS PART OF PLANNED SHUTDOWN IN ACCORDANCE WITH A PLANT PROCEDURE. THERE ARE'111 REACTORS HOLDING AN OPERATING LICENSE.

2.

COMPLICATIONS:-RECOVERY COMPLICATED BY EQUIPMENT FAILURES OR PERSONNEL ERRORS UNRELATED TO CAUSE OF SCRAM.

i

.3.

PERSONNEL RELATED PROBLEMS INCLUDE HUMAN ERROR, PROCEDURAL a

DEFICIENCIES, AND MANUAL STEAM GENERATOR LEVEL CONTROL i

PROBLEMS.

1 4.

"0THER" INCLUDES AUTOMATIC SCRAMS' ATTRIBUTED TO 'NVIRONMENTAL CAUSES(LIGHTHING),SYSTEMDESIGN,ORUNKNOWNCAUSE.

OEAB SCRAM DATA i

s Manual and Automatic Scrams for 1986 ------------------ 461 Manual and Automatic Scrams for 1987 ------------------ 439 Manual and Automatic Scrams for 1988 ------------------ 287-Manual and Automatic Scrams for 1989 ------------------ 244 ManualandAutomatic'Scramsfor1990(YTD06/20/90)--- 90 I

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.PERFORMANCEINDICATORSSlShlFICANTEVENTS ENCI.0SURE 4

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' PLANT NAME EVENT EVENT DESCRIPi!DN GTRSIGNIFICANCE DATE

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CllNTON:]

ON15/90 AFTER MAINTENANCE ON SERVICE NATER SYSTER, DUTLET VALVES 1 POTENilAL FOR DR ACTUAL DESRADeil0N.

l FOR ED6 SERVICE NATER COOLERS NERE MISPOS!!!0NED,!THIS OF SAFETY-RELATED EQUIPMENT.

CREATED A SliUAil0N NHERE NO C00LIN6 NATER NAS AVAILABLE FOR0]V1AND0]VllE065, l

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