ML20056H572

Summary of Operating Reactors Events Meeting 93-28 on 930728

ML20056H572
Person / Time
Site:	Grand Gulf, Sequoyah
Issue date:	08/05/1993
From:	Chaffee A Office of Nuclear Reactor Regulation
To:	Grimes B Office of Nuclear Reactor Regulation
References
OREM-93-028, OREM-93-28, NUDOCS 9309100101
Download: ML20056H572 (16)

Text

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l l August 5,1993 l

I MEMORANDUM FOR: Brian K. Grimes, Director j Division of Operating Reactor Support r  ;

I FROM: Alfred E. Chaffee, Chief I l Events Assessment Branch l Division of Operating Reactor Support ,

l

SUBJECT:

OPERATING REACTORS EVENTS BRIEFING 1 l JULY 28, 1993 - BRIEFING 93-28  !

I On July 28, 1993, we conducted an Operating Reactors Events  !

Briefing (93-28) to inform senior managers from offices of ImR, i OE, ACRS, and regional offices of selected events that occurred j since our last briefing on July.21, 1993. Enclosure 1 lists the i attendees. Enclosure 2 presents the significant elements of the j discussed events.  ?

Enclosure 3 contains reactor scram ..tatistics for the week ending l July 25, 1993. No significant events were identified for input (

into the NRC Performance Indicator Program. '

[ original signed by]  !

l

> 1 j Alfred E. Chaffee, Chief l Events Assessment Branch  !

Division of Operating  !

Reactor Support  ;

Enclosures:

As stated DISTRIBUTION.

centra 11 Files' l cc w/ enclosures

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cc: l T. Mur3ey, NRR (12G18) R. Clark (PDI-2)

F. Miraglia, NRR (12G18) C. Miller (PDI-2)

7. Gillespie, NRR (12G18) P. O'Connor (PDIV-1) 7 J. Partlow, NRR (12G18) H. Rood (PDIV-1)

• S. Varga, NRR (14E4)

J. Calvo, NRR (147.4)

G. Lainas, NRR (14H3)

J. Roe, NRR (13E4)

J. Zwolinski, NRR (13H24) ,

E. Adensam, NRR (13E4)

W. Russell, NRR (12G18)  !

J. Wiggins, NRR (7D26)  ;

A. Thadani, NRR (8E2)

S. Rosenberg, NRR (10E4) i C. Rossi, NRR (9A2)

B. Boger, NRR (10H3)

F. Congel, NRR (10E2) t D. Crutchfield, NRR (11H21)  :

W. Travers, NRR (11B19) ,

D. Coe, ACRS (P-315) '

! E. Jordan, AEOD (MN-3701)

• G. Holahan, AEOD (MN-9112)

L. Spessard, AEOD (MN-3701) ,

K. Brockman- AEOD (MN-3206)  !

S. Rubin, J JD (MN-5219) 1 M. Harper, AEOD (MN-9112) 1 G. Grant, EDO (17G21)

R. Newlin, GPA (2GS)

E. Beckjord, RES (NLS-007)

A. Bates, SECY (16G15)

T. Martin, Region I W. Kane, Region I C. Hehl, Region I  ;

S. Ebneter, Region II  !

E. Merschoff, Region II S. Vias, Region II '

J. Martin, Region III E. Greenman, Region III J. Milhoan, Region IV B. Beach, Region IV B. Faulkenberry, Region V K. Perkins, Region V bec: Mr. Sam Newton, Manager Events Analysis Department Institute of Nuclear Power Operations  !

700 Galleria Parkway '

Atlanta, CA 30339-5957 i f

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ENCLOSURE 1 LIST OF ATTENDEES ,

OPERATING REACTORS EVENTS FULL BRIEFT.NG (93-28)  ;

a JULY 28, 1993 ,

NAME OFFICE FAME OFFICE i

F. MIRAGLIA NRR J. TSAO NRR -

B. GRIMES NRR S. JONES NRR A. CHAFFEE NRR S. ROSENBERG NRR i R. DENNIG NRR M. BOYLE NRR i

! T. GREENE NRR W. LEFAVE NRR I

' J. CARTER NRR J. HICKMAN NRR E. GOODWIN NRR G. ZECH NRR l N. HUNEMULLER NRR J. HANNON NRR '

A. BYRDSONG NRR R. BARRETT NRR D. SKEEN NRR C. ROSSI NRR ,

E. BENNER NRR B. BOGER NRR T. YAMADA NRR S. VARGA NRR '

S. FLANDERS NRR J. SEGALA OE

] R. CLARK NRR D. COE ACRS  ;

R. WOODRUFF NRR j i

TELEPHONE ATTENDANCE  !

(AT ROLL CALL)

Recions Resident Inspectors I

. Region I Region II Region III )

l Region IV l Region V  ;

IIT/AIT Team Leaders Misc.

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ENCLOSURE 2 l

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1 OPERATING REACTORS EVENTS BRIEFING 93-28 LOCATION: 10 Bil, WHITE FLINT WEDNESDAY, JULY 28, 1993, 11:00 A.M.

I SUSQUEHANNA, UNIT 1 TURBINE GENERATOR PROBLEMS ,

h GRAND GULF PLUGGING OF RESIDUAL HEAT REMOVAL SUCTION LINE STRAINER l

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l PRESENTED BY: EVENTS ASSESSMENT BRANCH DIVISION OF OPERATING REACTOR SUPPORT, NRR

)

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{' 93-28

! SUSQUEHANNA, UNIT 1 -

! TURBINE GENERATOR PROBLEMS JULY 12, 1993 l l PROBLEM i

WHILE OPERATING AT 100% POWER, TWO TURBINE BLADES BROKE  ;

l LOOSE FROM THE TURBINE ROTOR.

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. CAUSE l t

THE ROOT CAUSE IS BEING INVESTIGATED BY THE LICENSEE AND GE.  ;

i SAFETY SIGNIFICANCE  ;

BROKEN ROTOR AND LOOSE TURBINE BLADES CAN BECOME MISSILES  !

l AND CAUSE SUBSTANTIAL DAMAGE. ALSO, BECAUSE OF THE l HYDR 0 GEN ASSOCIATED WITH THE GENERATOR, THERE IS A l

POSSIBILITY THAT A FIRE COULD START.  ;

DISCUSSION l e ON JULY 12, 1993, THE MAIN TURBINE Ti:~? PED ON HIGH t VIBRATIO HIGH VIBRATIONS COULD BE FELT IN THE i

i e THE TURBINE TRIP CAUSED THE REACTOR TO SCRAM.

e OPERATOR NOTICED A MAJOR CONDUCTIVITY EXCURSION IN THE  !

l l HOT WELL. THE CONDENSATE INFLUENT CONDUCTIVITY SPIKE UP TO 43 UMH0/CM. ,

! CONTACT: T. GREENE, NRR/ DORS AIT: NO

REFERENCES:

10 CFR 50.72 #25779, SIGEVENT: TBD .

1. 25808 AND MORNING REPORT DATED 07/23/93

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l SUSQUEHANNA, 93-28 l UNIT 1 l

FOLLOWUP i e THE "C" LOW PRESSURE TURBINE WAS INSPECTED. TWO BLADE -

ASSEMBLIES (BUCKETS) BROKE LOOSE FROM THE TURBINE ROTOR. G0UGING AND DEFORMATION OF THE STATIONARY DIAPHRAGMS AND THE MOVING BLADES OCCURRED. ,

, e INDICATIONS ARE THE BUCKETS FRACTURED ALONG A LINE THAT  !

COINCIDED WITH THE TOP R0W 0F ATTACHMENT PINS. EACH

, BUCKET IS ATTACHED TO THE ROTOR BY 9 PINS ARRANGED IN A 4 3-BY-3 ARRAY.

e THE TURBINE #8 BEARING MAY HAVE VIBRATED GREATER THAN t

15 MILS.

e TWENTY-FIVE TO THIRTY POUNDS OF DEBRIS FOUND IN THE "C" CONDENSER. THE DEBRIS WAS MOSTLY METAL AND INCLUDED THE TWO BLADES. ,

e ABOUT 50 - 100 TUBES WERE SHEARED OR HAVE HOLES IN THEM. THIS CAUSED THE HIGH CONDUCTIVITY IN THE HOT WELL. t

! e THE ROTORS IN THE TURBINE ARE THE NEW GE ONE PIECE FORGING MON 0 BLOC DESIGN. THE MON 0 BLOC DESIGN WAS INSTALLED AROUND 1986 TO ALLEVIATE THE TURBINE WHEEL CRACKING PROBLEM. ,

o GE PRELIMINARY CONCLUSION IS THAT THERE IS A CRITICAL HARMONIC AT ABOUT 120 HERTZ THAT CAUSED METAL FATIGUE.

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. . l SUSQUEHANNA, 93-28 UNIT 1 .

e THE LICENSEE EVALUATED TWO OPTIONS AND DECIDED TO G0 l WITH OPTION 2. T'iE OPTIONS:  :

1. REPLACING THE ROTOR WITH THE OLDER SHRUNK FIT l

TURBINE DESIGN l

2. REPAIR AND REBUCKET THE INTEGRAL ROTOR COMPLETELY. l i

e THE "B" LOW PRESSURE STAGE TURBINE WAS INSPECTED AND NO  :

l INDICATIONS OF A SIMILAR PROBLEM WERE FOUND.  ;

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. Cross Section of Low Pressure Turbine Rotor

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93-28 GRAND GULF PLUGGING 0F RESIDUAL HEAT REMOVAL

SUCTION LINE STRAINER JULY 2, 1989  !

! PROBLEM THE "A" RESIDUAL llEAT REMOYAL (RHR) LOOP STRAINER WAS )

i FOUND TO BE PLUGGED FOR THE SECOND TIME. j l

CAUSE SUPPRESSION POOL SLUDGE WAS NOT REMOVED AS INTENDED BY j LICENSEE AFTER THE FIRST STRAINER PLUGGING OCCURRENCE. l I

SAFETY SIGNIFICANCE l j A CONDITION CAUSING A RECOGNIZED UNDESIRABLE CONDITION '

(PLUGGED STRAINER) WAS NOT CORRECTED IN ACCORDANCE WITH j PLANT SAFETY COMMITTEE INTENTIONS. COULD RESULT IN COMMON MODE FAILURE OF SUPPRESSION POOL COOLING OR CORE COOLING  !

CAPABILITY. l i

DISCUSSION I

e THIS EVENT WAS IDENTIFIED TO HEADQUARTERS STAFF DURING l THE EVALUATION OF THE PERRY STRAINER DEGRADATION l PROBLEM AND WAS ALSO REPORTED BY REGION II AS A i CANDIDATE FOR THE SENIOR MANAGEMENT MEETING REGARDING  ;

POTENTIALLY SIGNIFICANT EVENTS THAT HAD NOT BEEN l PREVIOUSLY REPORTED.

l

! CONTACT: J. CARTER, NRR/ DORS AIT: NO

REFERENCE:

INSPECTION REPORT 89-17 SIGEVENT: YES

l GRAND GULF 93-28 l e DURING A QUARTERLY IST FUNCTIONAL TEST OF THE RHR PUMPS j IN MARCH 1988, THE "A" SUCTION PRESSURE WAS OBSERVED TO  !

BE LOWER THAN AN ACCEPTANCE LIMIT. l l

e DESIGN COOLANT FLOW RATES WERE ALWAYS ACHIEVED.  !

e THE STRAINER WAS CLEANED AND RETURNED TO SERVICE.

i e THE PLANT SAFETY REVIEW COMMITTEE MET AND DISCUSSED THE l PLANS TO CLEAN THE POOL. THE POOL WAS TO BE CLEANED BY  !

THE END OF THE NEXT REFUELING OUTAGE. CLEANING NOT  !

I ASSIGNED TO RESPONSIBLE GROUP.

e A STEP IN THE WORK INSTRUCTION TO VACUUM THE POOL WAS  !

DEFERRED. THE POOL WAS NOT THOROUGHLY CLEANED.  !

e DURING A SUBSEQUENT QUARTERLY IST FUNCTIONAL TEST IN JULY 1989, THE "A" SUCTION PRESSURE AGAIN DID NOT MEET l THE ACCEPTANCE CRITERIA. I e THE SUPPRESSION P0OL WAS CLEANED USING A VACUUM TO l

REMOVE DEBRIS AND A HYDROLASER TO CLEAN WALLS. DIVERS i WERE ALSO USED.

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s CLEANLINESS CRITERIA WERE DEVELOPED FOR FUTURE CLEANING  !

ACTIVITIES.

• NO FURTHER INCIDENTS OF LOW SUCTION PRESSURE HAVE OCCURRED.

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!' GRAND GULF -

3- 93-28 j FOLLOWUP ,

e INFORMATION NOTICE 93-34 AND BULLETIN 93-02 WERE ISSUED  ;

AS A RESULT OF THE PERRY EVENT; THEY ALERTED INDUSTRY TO THE PROBLEM.  !

! e AN EVALUATION OF THE EVENT INDICATED THAT THE PRESSURE j

DROP ACROSS THE STRAINER WAS ABOUT 6 PSI, THE SAME AS FOR THE PERRY STRAINER. l 1 ,

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ENCLOSURE 3

, REACTOR SCRAM Reporting Period: 07/19/93 to 07/25/93 l-t YTD YTD ABOVE BELOW YTD PfTl P,LANT & UNIT POWER M cal'SE COMPLICATIONS j)J M E 07/19/93 HADDAM HECK 1 0 SA Operating Error NO 1 1 2 l

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hote: Veer To Date (YTD) Totals include Events Within The Calendar Year Indicated By The End Date of The Specified Reporting Period l ETS-10 page:S ggfg3fp3 i

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l . COMPARISON OF WEEKLY SCRAM STATISTICS WITH INDUSTRY AVERAGES l

PER100 ENDING ,

07/25/93 l NUMBER 1993 1992 1991* 1990* 1989*

OF WEEKLY WEEKLY WEEKLY WEEKLY WEEKLY SCRAM CAUSE SCRAMS AVERAGE AVERAGE AVERAGE AVERAGE AVERAGE j (YTD)

POWER GREATER THAN OR EQUAL TO 15%

EQUIPMENT FAILURE

• 0 1.9 2.6 2.9 3.4 3.1 DESIGk/ INSTALLATION ERrast* D 0.1 - - - -

OPERATING ERROR

• 0 0.3 0.2 0.6 0.5 1.0 MAINTENANCE ERROR

• O 0.5 0.4 - - -

EXTERNAL

• O 0.1 - - - -

OTHER* 0 0.0 0.2 - -

0.1 Subtotal 0 2.9 3.4 3.5 3.9 4.2 POWER LESS ThAN 15%

EQUIPMENT FA! LURE

• O 0.4 0.4 0.3 0.4 0.3 DESIGN / INSTALLATION ERROR

• O 0.0 - - - -

OPERATING ERROR

• 1 0.2 0.1 0.2 0.1 0.3 MAINTENANCE ERROR

• O 0.0 0.1 - - -

EXTERNAL

• O 0.0 - - - -

OTHER* O 0.0 0.1 - - -

Subtotal 1 0.6 0.7 0.5 0.5 0.6 j TOTAL 1 3.5 4.1 4.0 4.4 4.8 I l

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1993 1992 1991 1990 1989 NO. OF WEEKLY WEEKLY WEEKLY WEEKLY WEEKLY SCRAM TYPE SCRAMS AVERAGE AVERAGE AVERAGE AVERAGE AVERAGE (YTD)

TOTAL AUTOMATIC SCRAMS 1 2.5 3.1 3.3 3.2 3.9 TOTAL MANUAL SCRAMS 0 1.1 1.0 0.7 1.2 0.9 TOTALS MAY DIFFER BECAUSE OF ROUNDING OFF

• Detailed breakdown not in database for 1991 and earlier

- EXTERhAL cause included in EQUIPMENT FAILURE

- MAINTENANCE ERROR and DESIGN / INSTALLATION ERROR causes included in DPERATING ERROR

- OTHER cause included in EQUIPMENT FAILURE 1991 and 1990 l

ETS-14 Page: 1 08/03/93

NOTES

1. PLANT SPECIFIC DATA BASED ON INITIAL REVIEW OF 50.72 REPORTS FOR THE WEEK OF INTEREST. PERIOD IS MIDNIGHT SUNDAY THROUGH MIDNIGHT SUN 7AY. ,

SCRAMS ARE DEFINED AS REACTOR PROTECTIVE ACTUATIONS WHICH RESULT IN ROD  !

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. I I

2. PERSONELL RELATED PROBLEMS INCLUDE HUMAN ERROR, PROCEDURAL DEFICIENCIES, I AND MANUAL STEAM GENERATOR LEVEL CONTROL PROBLEMS. j

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

4. "OTHER" INCLUDES AUTOMATIC SCRAMS ATTRIBUTED TO ENVIRONMENTAL CAUSES (LIGHTNING), SYSTEM DESIGN, OR UNKNOWN CAUSE.

OEAB SCRAM DATA Manual and Automatic Scrams for 1987 ------------------ 435 Manual and Automatic Scrams for 1988 ------------------ 291 Manual and Automatic Scrams for 1989 ------------------ 252 Manual and Automatic Scrams for 1990 ------------------ 226 Manual and Automatic Scrams for 1991 ------------------ 206 Manual and Automatic Scrams for 1992 ------------------ 212 i Manual and Automatic Scrams for 1993 --(YTD 07/25/93)-- 107 l i

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