IR 05000353/1997009

Insp Rept 50-353/97-09 on 971010-980116.Violations Noted. Major Areas Inspected:Operations,Maintenance,Engineering & Plant Support

ML20216G732
Person / Time
Site:	Limerick
Issue date:	03/11/1998
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20216G678	List: IR 05000353/1997009 ML20216G674
References
50-353-97-09, 50-353-97-9, NUDOCS 9803200074
Download: ML20216G732 (34)

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k U. S. NUCLEAR REGULATORY COMMISSION

REGION I

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Docket No:

50-353 l

l Report No:

50-353/97-09 Licensee:

PECO Energy Facility:

Limerick Generating Station, Unit 2

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Location:

Limerick, PA Dates:

October 10,1997, through January 16,1998 Inspectors:

C. G. Cahill, Reactor Engineer R. L. Fuhrmeister, Sr. Reactor Engineer (Part-Time)

i Approved by:

William H. Ruland, Chief Electrical Engineering Branch Division of Reactor iafety i

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f-l 9803200074 980311 PDR ADOCK 05000353

PDR

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EXECUTIVE SUMMARY This inspection includes aspects of licensee operations, maintenance, engineering, and l

plant support. The inspection focused on PECO's root cause analysis and corrective

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actions with respect to the failure of D21 EDG. The report period was October 10,1997 l

through January 16,1998.

Ooerations The Plant Operation Review Committee (PORC) meeting, conducted on October 25,

1997, was professional and safety focused. The PORC members demonstrated a questioning attitude and healthy skepticism in reviewing the root cause team presentation (Section 01).

Maintenance

The maintenance was conducted in a deliberate manner with particular attention paid to foreign material exclusion (FME) and in-process parts control. Procedural compliance was demonstrated throughout the evolution. PECO maintained the work site in clean, orderly and well lighted condition (Section M1).

• D21 Emergency Diesel Generator (EDG) had the highest valid start failure rate of the eight Limerick EDGs. The maintenance that was executed adequately corrected the particular failure. Surveillance procedures requiring vibration monitoring and recording have been improved (Section M2).

Enaineerina

PECO had not properly identified and corrected possible reversed bearings after finding reversed bearings on the E4 EDG (Peach Bottom) and D22 EDG (Limerick).

Neither formal evaluation of the bearing nonconformance nor complete bearing inspections were performed after the E4 and D22 bearing reversals. This is an apparent violation of Criterion XVI, Corrective Action (Section E1).

• The licensee had identified the most probable cause of the D21 EDG fai!ure. The licensee employed a systematic root cause analysis process, questioning attitude and comprehensive engineering evaluation in the determination of the complex bearing failure mechanism (Section E1).

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PECO had properly identified and executed the technical specification requirements for demonstrating the D21 EDG operable. PECO demonstrated a thorough engineering review process and good oversight throughout operability testing (Section E2).

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f Plant Sucoort The fire in D21 burned for less than two minutes and the fire protection system was e

operating properly. A visual inspection of the fire suppression system, by the inspectors, indicated that it was in the proper working order. The fire brigade responded rapidly to the scene and executed the appropriate immediate action to combat the casualty (Section F8).

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SUMMARY IMPN6PERLY INSTALLED BEARING IDENTIFIED ON D22 FACILITY / UNI'T INVOLVED: LG 2 ISSUE OCCURRED DATE/ TIME _06DEC95 16:00 RESPONSIBLE EAC FACILITY: LG_

ISSUE DISCOVERED DATE/ TIME: 10MAY96 12:00 PRINT DATE/ TIME: 14JAN98 11:34

==== e----

- --- ---============== CLASSIFICATION

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NQA REVIENER ---------------- :

NOT REQUIRED RLK1 13MAY96 HP REVI EWER ----------------- :

NOT REQUIRED SRD1 14MAY96 EAC

DRIEHAUS PR PRD1 14MAY96

+ - - - - - - - - - - - - -

======================- -- ------- ASSIGNMENT==---

= = = - - - -

-===========

ASSIGNED ORG :

LMM2 ASSIGNED PIRL:

COOK JP

. INTERIM CORRECTIVE ACTION TAKEN:

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SRD1 14MAY96 THIS ISSUE WILL BE DISCUSSED BY THE TEAMS INVOLVED IN RLK1 06JUN96 THE 18 MONTH INSPECTION SCHEDULED IN WORK WEEK 96/24 ON RLK1 06JUN96 ON D23. MAINTENANCE TEAMS 6 AND 7.

RLK1 06JUN96 SEE EVAL 1 RLK1 06JUN96 ASSIGNED ORG SUPERVISOR DENNETT SR SRD1 14MAY96

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EVALUATION -----===------ u=====-

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ADDITIONAL ISSUE INFORMATION/ ISSUE DISPOSITION:

THE NUMBER 8 CONNECTING ROD BEARING CAP WAS INSTALLED RLK1 13MAY96 180 DEGREES OUT THEREFORE THE BEARING LINER PINS DID RLK1 13MAY96

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NOT LINE UP. THIS CONDITION CAUSED THE BEARING LINER RLK1 13MAY96 PINS TO EXTRUDE THE ALUMINUM BEARING MATERIAL INTO THE RLK1 13MAY96 AREA MACHINED FOR THE SWEEP. NO DAMAGE WAS DONE TO THE RLK1 13MAY96 CRANKSHAFT AND ONLY SLIGHT INDICATION OF A RUB WAS RLK1 13MAY96 IDENTIFIED ON THE BEARINGS BOTH TOP AND BOTTOM HALVES.

RLK1 13MAY96 THE 18 MONTH INSPECTION COMPLETED IN DEC. OF 1995 WAS RLK1 13MAY96 DONE UNDER WORK ORDER R0529922.

RLK1 13MAY96 DISCUSSIONS WITH THE FACTORY REP ON SITE WHEN THIS RLK1 13MAY96

JAN-14-1998 14f13 LIMERICK / NRC 610 323 6590 P.04

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PECO ENERGY COMPANY

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PEP ISSUE

PAGE: 0005

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ISSUE NBR: I0005646 STATUS /DATE:_COMPLT 23DEC96 I.AST UPDATE: 10MAY97 08:51 ISSUE SUMMARY: IMPROPERLY INSTALLED BEARING IDENTIFIED ON D22 FACILITY / UNIT INVOLVED: LG 2 ISSUE OCCURRED DATE/ TIME: 06DEC95 16:00 RESPONSIBLE EAC FACILITY: LG ISSUE DISCOVERED DATE/ TIME: 10MAY96 12:00 PRINT DATE/ TIME: 14JAN98 11:34 l

=========e=-

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EVALUATION====-

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l ISSUE WAS IDENTIFIED INDICATE THAT THIS CONDITION WOULD RLK1 13MAY96 NOT HAVE CAUSED A CATASTROPHIC FAILURE OF THE ENGINE.

RLK1 13MAY96

RLK1 13MAY96 THERE WERE NO INDUSTRIAL SAFETY ELEMENTS RELATED TO RLK1 13MAY96 THIS ISSUE.

RLK1 13MAY96 THERE WERE NO NUCLEAR SAFETY ISSUES ASSOCIATED WITH-RLKL-13MAY96 THIS ISSUE.

RLK1 13MAY96 THERE WERE NO RADIOLOGICAL IMPACTS WITH THIS ISSUE RLK1 13MAY96

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RLK1 13MAY96 THIS ISSUE IS NOT RECOMMENDED FOR PUBLICATION ON THE RLK1 13MAY96 INPO NETWORK.

RLK1 13MAY96

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RLK1 13MAY96 THIS ISSUE SHOULD BE CONSIDERED REPEAT MAINTENANCE.

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13MAY96 CAUSES OF ISSUE:

THE TECHNICIAN THAT WAS INVOLVED WITH THE #8 BEARING RLK1 04JUN96 INSPECTION IN DECEMBER OF 1995 WAS INTERVIEWED ON 6/3/96.

RLK1 04JUN96 FOLLOWING ARE COMMENTS FROM THAT INTERVIEW.

RLK1 04JUN96 THE FACTORY REP WAS ON THE JOB WITH HIM AT THE TIME RLK1 04JUN96 OF THE INSPECTION.

RLK1 04JUN96 THEY HAD A DISCUSSION ABOUT THE IMPORTANCE OF MAKING RLK1 04JUN96 SURE THE BEARING ASSEMBLY WAS PUT TOGEATHER PROPERLY RLK1 04JUN96 WITH THE MATCH MARKS IN THE RIGHT LOCATION.

RLK1 04JUN96

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THE MATCH MARKS WERE CHECKED AFTER THE CONNECTING RLK1 04JUN96 ROD CAP WAS INSTALLED.

RLK3 04JUN96 THE TECH INVOLVED IN THE DEC 1995 INSPECTION WAS NOT RLK1 04JUN96 DIESEL QUALIFIED.

RLK1 04JUN96

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RLK1 04JUN96 THE INSTRUCTOR FOR DIESEL TRAINING WAS ALSO INTERVIEWED RLK1 04JUN96

~_REGARDING THIS ISSUE. FOLLOWING ARE COMMENTS FROM THE RLK1 04JUN96 INTERVIEW.

RLK1 04JUN96 THE BEARING INSERTS (SHELLS) CAN BE INSTALLED IN RLK1 04JUN96 ANY LOCATION, TOP OR BOTTOM,WHEN THEY ARE NEW AS RLK1 04JUN96 __

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LONG AS THE ALIGNMENT PINS ARE IN THE PROPER RLK1 04JUN96 LOCATION.

RLK1 04JUN96 ALL MATCH MARKS ARE TO BE ON THE CONTROL SIDE OF RLK1 04JUN96

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THE ENGINE FACING THE CONTROL END.

RLK1 04JUN96 HE HAS SEEN THIS CONDITION BEFORE AND DOES HAVE RLK1 04JUN96 EXAMPLES THAT ARE USED IN TRAINING TO EMPHASIZE RLK1 04JUN96 THE NEED TO INSTALL THE BEARING SHELLS PROPERLY.

RLK1 04JUN96 THERE ARE TEN DIFFERENT COMBINATIONS THAT COULD RLK1 04JUN96

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BE USED TO INSTALL THE CONNECTING ROD AND BEARING RLK1 04JUN96 SHELLS. THERE IS ONLY ONE RIGHT WAY TO INSTALL RLK1 04JUN96 A USED SHELL THAT HAS BEEN IN SERVICE. TBIS IS DUE RLK1 04JUN96 TO THE FACT THAT THAT THE BEARING SHELL BAS BEEN RLK1 __

04JUN96 i

JAN-14-1998 14: 14 L1MERICK / NRC 610 323 6590 P.05

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PECO ENERGY COMPANY

PEP ISSUE

PAGE: 0006

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ISSUE NBR: 10005646 STATUS /DATE: COMPLT 23DEC96 LAST UPDATE: 10MAY97 08:51 ISSUE SUNNARY: IMPROPERLY INSTALLED BEARING IDENTIFIED ON D22 FACILITY / UNIT INVOLVED: LG 2 ISSUE OCCURRED DATE/ TIME: 06DEC95 16:00 RESPONSIBLE EAC FACILITY: I4 ISSUE DISCOVERED DATE/ TIME: 10MAY96 12:00 PRINT DATE/ TIME: 14JAN98 11:34

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EVALUATION =--- =

- = = = - - - - - = = = = = = = = = = = = = =

-BROKEN IN IN THE INSTALLED POSITION.

RLK1 04JUN96

• * * * e t e * * * e * * ** * * * * * * * * * * * * * * * * * * a m e * * * * e e * * * * * * * *

RLK1 04JUN96 ene*****************amenese***********************

RLK1 04JUN96 CONCLUSION.

RLK1 04JUN96

__THIS CONDITION MAY HAVE OCCURED DURING A PRIOR

_RLK1 04JUN96 INSPECTION HOWEVER IF THAT WERE THE CASE HOvi'DID WE NOT RLK1 04JUN96 RECOGNIZE THE FACT THAT WE HAD A BEARING RUS AND EXTRA RLK1 04JUN96 HOLES PUNCHED INTO THE BEARING SHELL DURING THE DEC. 1995 RLK1 04JUN96 INSPECTION. IN EITHER CASE THE ROOT CAUSE WOULD BE RLK1 04JUN96 SIMILAR. LESS THAN ADEQUATE ATTENTION TO DETAIL / HUMAN RLKl.

04JUN96 ERROR.

RLK1 04JUN96 RLK1 04JUN96

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GENERIC IMPLICATIONS:

THIS IS THE.FIRST TIME THAT AN INCIDENT OF THIS KIND HAS RLK1 04JUN96 OCCURRED AT LGS TO MY KNOWELDGE THEREFORE I WOULD NOT RLK1 04JUN96 CONSIDER IT GENERIC.

RLK1 04JUN96 COMPLETED CORRECTIVE ACTIONS TO PREVENT RECURRENCE:

A STRONGER FOCUS ON SENDING RM TECHNICIANS TO DIESEL RLK1 06JUN96 TRAINING HAS BEEN INSTITUTED IN MAINTENANCE. THIS WILL RLK1 06JUN96 HELP THE TEAMS THAT DO NOT HAVE DIESEL QUALIFIED TECES RLK1 06JUN96 TO SUPPORT THE BACK SHIFTS.

RLK1 06JUN96 PEP ISSUE APPROVED TO PROCEEDE TO PLNNED STATUS PER SRD1 13JUN96 DISCUSSIONS BETWEEN E.F.SPROAT AND S.R.DENNETT SRD1 13JUN96

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JAN-14-1998 14: 15 L1MERICK / NRC Eil 323 6590 P.06

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PECO ENERGY COMPANY

PEP ISSUE

PAGE: 0007

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ISSUE NBR: I0005646 STATUS /DATE: COMPLT 23DEC96 LAST UPDATE: 10MAY97 08:51 ISSUE SUMMARY: IMPROPERLY INSTALLED BEARING IDENTIFIED ON D22 FACILITY / UNIT INVOLVED: LG 2 ISSUE OCCUnnPR DATE/ TIME: 06DEC95 16:00 RESPONSIBLE EAC FACILITY: LG ISSUE DISCOVERED DATE/ TIME: 10MAY96 12:00 PRINT DATE/ TIME: 14JAN98 11:34

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BASIS FOR VERIFICATION / REJECTION:

NO SCORE FDR1 14JUN96

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COMPLETED BY PIRL ------

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KROPP R.L.

SRD1 13JUN96 ASSIGNED ORGANIZATION APPROVAL:

DENNETT SR SRD1 13JUN96 HP APPROVAL:

NOT REQUIRED SRD1 14MAY96 EAC APPRO7AL:

ROAK FDR1 14JUN96 i

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..JAN-14-1998 14:15 LIMERICK / NRC 610 323 6590 P.07 V

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PECO ENERGY COMPANY

PEP I S S O'E

PAGE: 0009

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ISSUE NBR: I0005646 STATUS /DATE: COMPLT 23DEC96 LAST UPDATE: 10MAY97 08:51 ISBUE SUMMARY: IMPROPERLY INSTALLED BEARING IDENTIFIED ON D22 FACILITY / UNIT INVOLVED: LG 2 ISSUE OCCURRED DATE/ TIME: 06DEC95 16:00 RESPONSIBLE EAC FACILITY: LG ISSUE DISCOVERED DATE/ TIME: 10MAY96 12:00 PRINT DATE/ TIME: 14JAN98 11:34

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END OF PEP ISSUE DETAIL PRINT========-----------====

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JAN-14-1998 14:15 LIMERICK / NRC 610 323 6590 P.08

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PECO ENERGY COMPANY

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0000 PEP I S S U E 0000 PAGE: 0010 ISSUE NUMBER: I0005646 ISSUE STATUS: COMPLT STATUS DATE : 23DEC96 LAST UPDATE : 10MAY97 PRINT DATE

14JAN98

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-===--== EVALUATION==--===============---=======

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EVALUATION NBR:

ORIG DATE ASSIGNED:

EVALUATING ORG:

LMMS EVAL DUE DATE: 08JUN96 EVAL ASIGND TO:

J.ORLANDO DATE ASSIGNED: 06JUN96 EVAL REQUEST ORG: LMMS EVAL REQUESTOR:

_R.L.KROPP EVAL STATUS

COMPLT EVAL RETURNED BY: JA02 IMPORTANCE CODE: 2 OEAP: R SCHEDULE CODE NOTG DATE FIXED: T

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EVAL DESC: REVIEW THIS PEP PRIOR TO D23 WORK IN 96/24 PLEASE REVIEW PEP 10005646 PRIOR TO THE START OF THE 18 RLK1 06JUN96 MONTH INSPECTION -SCHEDULED IN WORK WEEK 96/24 RLK1 06JUN96 JA02 06JUN96

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PEP 10005646 REVIEWED WITH ALL TEAM 7 MEMBERS ON 6/6/96 JA02 06JUN96

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JAN-14-1998 14:16 LIMERICK / NRC 610 323 6590 P.09

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PECO ENERGY COMPANY

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PEP I S S U E *006 PAGE: 0011

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l ISSUE NUMBER:__IOOOS646 ISSUE STATUS: COMPLT STATUS DATE : 23DEC96 LAST UPDATE : 10MAY97 PRINT DATE

14JAN98

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EVALUATION====- -

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m-EVALUATION NBR:

ORIG DATE ASSIGNED:.IlJUN96 EVALUATING'ORG:

LRM EVAL DUE DATE: 31JUL96 EVAL ASIGND TO:

HEIDENFELDER,AW DATE ASSIGNED: 11JUN96 EVAL REQUEST ORG:__LMM5

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EVAL REQUESTOR:

R.L.KROPP EVAL STATUS

COMPLT EVAL RETURNED BY: HOFFMAN,LF IMPORTANCE CODE: 3 OEAP: R SCHEDULE CODE: NOTG DATE FIXED:.T

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EVAL DEScr INCLUDE REVIEW OF THIS ISSUE IN DIESEL TRAINING PLEASE REVIEW THIS PEP IN UP COMMING TRAINING CLASSES.

RLK1 llJUN96 THIS ISSUE HAS BEEN DISCUSSED WITH AL HEIDENFELDER PRIOR RLK1 llJUN96 TO WRITING THE PEP.

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R.KROPP 2351 RLK1 11JUN96 wu*

LFH1 11JUN96 AL, PLEASE REVIEW AND DETERMINE WHAT TRAINING MATERIALS LFH1 llJUN96 NEED TO BE CHANGED.

LFH1 11JUN96 wu*

LFH1 llJUN96

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NO TRAINING MATERIALS NEED TO BE CHANGED OR REVISED. THE AWH1 27JUN96 INFORMATION CONCERNING PROPER POSITIONING OF ALL THE AWH1 27JUN96 BEARINGS WITHIN THE DIESEL ENGINE IS INCLUDED IN LP-12401 AWH1 27JUN96 AND 12406.

EXAMPLES OF MISPOSITIONED BEARINGS ARE AWH1 27JUN96 PRESENTED AND EXPLAINED ALONG WITH THE BEARINGS IN AWH1 27JUN96 QUESTION FROM THIS PEP. THIS PEP WAS REVIEWED IN THE AWH1 27JUN96

_ CLASS THAT WAS OFFERED FROM 6/10/96 TO 6/24/96 AND WILL AWH1 27JUN96

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BE REVIEWED IN THE ONLY REMAINING SCHEDULED CLASS BEING AWH1 27JUN96 OFFERED. THIS OFFERING IS FROM 10/17/96 TO 10/31/96.

AWH1 27JUN96 THIS SATISFIES BOB KROPP'S REQUEST TO HAVE THIS PEP AWH1 27JUN96 PRESENTED TO THE TWO SCHEDULED DIESEL CLASSES.

AWH1 27JUN96 END OF EVAL.

AWH1 27JUN96 DPW1 10JUL96

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I TOTAL P.09 o

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The following maintenance activity was reviewed:

On September 21, 1994, the inspectors observed the tightening of an electrical connection at the breaker for a lube oil pump for the Unit 2 recirculation pump motor generator set.

Several months ago, plant personnel observed, through the use of thermography, that the C phase connection at the breaker was hotter than the other two phases, and had been monitoririg the breaker since then. The C phase was at approximately 210 degrees Fahrenheit, and other two phases were at approximately 150 degrees Fahrenheit. A ra)id

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temperature increase to approximately 400 degrees occurred in Septem)er, so the work was appropriately planned.

The work was performed with the breaker energized. The inspectors observed good pre-job briefings knowledgeable personnel, good coordination between maintenance and operations personnel, good supervisory oversight at the breaker, and good safety piactices by the workers.

Unfortunately, the tightening only resulted in a temperature decrease of approximately 50-60 degrees, and the pump was taken out of service later for repairs.

2.2 D21 Emergency Diesel Generator 5 year Overhaul l

On August 26, 1994. with Unit 2 at 100% of rated power, an overspeed trip test was performed on the D21 emergency diesel generator (EDG) in preparation for the engine's 5-year overhaul.

Limerick has eight Colt Fairbanks Morse Opposed Piston Engines (four per unit).

During the performance of the overspeed trip test the engine's speed inadvertently exceeded a maximum indicated speed of 1500 rpm for 15 seconds.

(The normal operating speed for the engine is 900

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rpm.) PECO Energy's review of the event concluded that the test method prevented the overspeed trip from functioning.

The maximum speed achieved was estimated (using a strip chart recorder) to be between 1600 and 1700 rpm. The test method described in the test 3rocedure directs an operator to mechanically bar the fuel rack wit 1 a large screwdriver, causing the overspeed condition. This method was approved by the vendor and had been successfully used to overspeed trip test all four Unit 1 EDGs and one of the other Unit 2 EDGs. During this event, however, the barring method was varied in that instead of a quick jerk of the screwdriver against the fuel rack, as had been done on the previous engines tested, a slow constant pressure with the screwdriver was applied to the fuel rack to increase engine speed to the trip setpoint.

The operator's expectation was that the overspeed trip would occur between 1035 and 1053 ram.

Apparently, the pressure exerted by the screwdriver prevented t1e fuel control arm from pivoting (that is, going closed) following the overspeed trip actuation.

PECO Energy contacted both the engine and generator vendors for a list of recommended items to be inspected / replaced as a result of the overspeed. The

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connecting rod bolts, insert bolts and fuel injection pumps were replaced.

The bearings, cam shaft, blower and governor were all ins)ected. A dye penetrant check was performed on the entire upper crank slaft and high stress points on the lower crank shaft. The vendor representative for the engine was present for the complete overhaul and a vendor (The Louis Allis Company)

representative for the generator performed an onsite ins)ection of the generator. The generator dove tail wedges and pole bloccs were checked for looseness.

The pole end coils were checked for bending and the poles were l

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meggered. Additionally, the dove tails were checked for-yielding by checking

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for a gap between the spider and the pole. The 5-year overhaul was completed with all appropriate ins)ections performed, and no indication of any engine l

degradation was found.

3ECO Energy performed the overspeed test prior to the completion of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> endurance run.

PECO Energy acquired a special tool

'from Woodward Governor that was attached to the governor to exercise the governor linkage to increase engine speed. This method did not impinge the fuel rack. The inspector observed the performance of the overs)eed test. A pre-job briefing was given in the control room to familiarize tie staff with the new test method.

The brief was comarehensive and included a clear expectation of what should be done if tie diesel did not trip in the required band of 1035 to 1055 RPM. The test was performed successfully with the diesel tripping at 1038 rpm.

On September 12, 1994, during the performance of the D21 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> endurance run, a fuel oil fire was discovered by a maintenance technician monitoring the diesel run. The estimated duration of the fire was five to ten minutes based

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on the time period the technician was out of the diesel generator room. The

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fire was caused by a leaking fuel oil connection on the supply to the number

nine fuel oil injector. On the preceding evening, a three to four drop per

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minute leak was identified from the same fuel oil connection, and an equipment trouble tag (ETT) was generated.

Later that morning the maintenance

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-technician noted the leak had increased slightly and left the diesel room to contact his supervisor so that someone could come out and inspect the leak.

When he returned from making the call he observed black smoke and flames in the area of the number nine cylinders.

He immediately notified the control room of the fire so that the engine could be secured and then extinguished the

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l fire with two bursts of a C0 fire extinguisher. The fire brigade responded

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to the diesel room and the fire brigade leader noted a 150 drop per minute

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leak at the connector, as the fuel line depressurized, indicating that the

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' leak had increased considerably resulting in a fire.

- The inspector. observed the repair activities on D21 following the fire.

The fuel oil connection was repaired and the engine was cleaned and thoroughly inspected.

Specifically, the fuel line linkage and bearings were checked, along with the injector nozzles and pumps for the number seven through eleven

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cylinders. Additionally, the vendor was contacted to determine if anything

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else needed to be inspected.

Maintenance also took this opportunity to repair some minor jacket water cooling leaks identified during the break-in runs.

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The repairs were successfully completed, with no other problems identified as a result of the fire.

D21 completed its 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> endurance run on September

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15, 1994 and the diesel was declared operable.

2.3 D22 Emergency Diesel Generator Gear Replacement j

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On July 31, 1994, the Unit 2 D22 emergency diesel generator was declared h

inoperable for a planned maintenance outage using maintenance procedure (M)-

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020-025. Diesel Engine 5-year Examination and General Maintenance.

This procedure required technicians to visually examine the water pump drive gears,

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lubricating oil pum) drive gear and the lower air start distributor drive gear for damage and/or a) normal wear. When this was done on August 3, 1994.

technicians found abnormal wear patterns, fretting, and pitting on the i

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flexible drive gear, flexible drive driven gear, and to a lesser extent, the water aump driven gears.

(The flexible drive gear is connected to the lower

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crankslaft and drives the auxiliary diesel pumps.) PECO Energy decided to j

replace all six damaged gears and determine the root cause of the problem. On

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l August 17, 1994, the post maintenance test and surveillance runs were completed, and D22 was declared operable.

PECO Energy's preliminary conclusion for the cause of the deterioration of the gears was the misalignment of the gear assembly of the pump flexible drive. This conclusion was supported by findings of a local gear manufacturing company. The investigation of the cause of the gear assembly misalignment was still in progress at the end of the last inspection period (August 15. 1994).

The inspector reviewed the final investigation reports from PECO Energy, the i

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local gear manufacturing company, and the consultant brought in to assist in l

l-the troubleshooting activities following the event.

The cause of the gear assembly misalignment was that the flexible drive bracket (housing) was not within fabrication tolerances necessary to provide 3 roper alignment.

This resulted in a non-perpendicular condition between t1e flexible drive bearing bracket mounting flange and the flexible drive shaft.

PECO Energy's final root cause determination was that the equipment problem was caused by a deficiency in the manufactured part, namely the flexible drive bracket, supplied by the vendor.

PECO Energy has returned all the affected parts and investigation findings to the vendor for their evaluation and has asked the

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vendor to review the event for reportability under the recuirements of 10 CFR Part 21. Reporting of Defects and Noncompliance.

The vencor was also asked, by PECO Energy, to inform them of their determination regarding reportability.

The inspector concluded that PECO Energy's overall response to this event was-excellent.

Resources from the Limerick site, Chesterbrook Office, and the Valley Forge Laboratory were all brought together to resolve this problem.

It should be noted that the use of a consulting engineer and the local gear

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company provided an additional independent review of PECO Energy's findings.

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2.4 Unit 2 Feedwater Check Valve (041-2F010A) Bearing Cover Leak On September 8.1994, plant personnel noted that Unit 2 drywell unidentified leakage had increased from approximately 0.7 gpm to approximately 5.2 gpm.

Unit 2 was at approximately 25% power at the time, as power had been reduced to perform maintenance on the generator stator cooling system.

Early on September 8. )lant management decided to deinert the drywell and make an entry to identify tie source of the leak. The source of the leakage was identified as coming from the shaft bearing cover for the 10A feedwater check valve, and was estimated to be approximately equal to the increase in the leakage that was noted.

Plant personnel first tried to reduce the leakage by retorquing the eight bolts for the cover, but this had little effect on the leakage.

Plant management next decided to attempt to reduce the leakage by injecting a

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sealant through the bolt holes.

On September 9.1994, plant personnel L

replaced five stud nuts, one-at-time, with special nuts used for injecting the

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sealant, and then injected the sealant. This process essentially stopped the leakage. Additionally, a catch basin was installed under the valve to direct any leakage from the valve to the drywell eauipment drain where it would be l

' tracked as identified leakage.

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FEB 09 '98 09:52AM P.1/2 a

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ENFORCEMENT PANEL WORKSHEET

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REGION 1

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1. Date of Enforcement Paneh

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• Licensee: PECO Nuclear

• Facility: Limerick Generating Station, Unit 2

• License Type (non-reactor):

• Docket No(s): 50-353 l

• License No(s):

• Inspection /OI Report No(s): 97-09

• Date ofIdentification: January 16,1998

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• Date of Exit Meeting /OI Report Date: January 16,1998 l

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• Panel Chairman (SES Sponsor):

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• Responsible Branch Chief / Lead Inspector: William H Ruland

1. Entbrr+==t Representative:

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1. Headquarters attendees:

• 1. Brief Summary ofIssues/ Potential Violations: On May 10,1997 PECO had identified that a D22 Emergency Diesel Generator (EDG) connecting rod bearing was improperly installed.

This was the second known event in which PECO Nuclear EDG connecting rod bearings were found to be improperly installed. PECO took insufficient corrective action to properly identify and correct this nonconformance by failing to inspect the remaining Limerick EDGs.

Additionally, the licensee failed to determine if the nonconformance of the connecting rod boarings was acceptable.

• 2. Regional Recommended Enforcement Strategy: Recommend issuing a SL IV with no required response by the utility. PECO has taken action to correct this violation and implemented measures to prevent its recurrence as documented in IR 97-09 and the Limerick Generating Station, Unit 2 Special Report for a Valid Emergency Diesel Generator Test Failure, November 10,1997.

• 3. Analysis ofRoot Cause/ Significance: PECO undertook extensive research and analysis to determine that the most probable root of the D21 failure was improper installation of the #4 lower connecting rod bearing.

b. Safety Significance (actual or potential): Class 1E power supply being made inoperable as a result of a fire (required declaration of an alert).

c.

Risk Significanc.e (qualitative or Quantitative): This is the first recorded instance in which improper installation of connecting rod bearings, specifically reversal of one bearing shell, resulted in a catastrophic failure of an EDG.

d. RegnIntory Significance:

• 4. Apparent Severity Level (s) and Basis: SL IV because the violation is more than minor and this is a repeat occurrence ofimproper bearing installation on PECO EDGs.

• 5. Application of Enforcement Policy:

Enforcement History Last 2 years /2 inspections: f, FEB 09 '90 08:52AM P.2/2

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b. Is Credit Warranted forIdentification? Explain: No, because the problem was found as a result of the failure.

c.

Is Credit Warranted for Corrective Actions? Explain: No, PECO took insufficient conective action to properly identify and correct this nonconformance by failing to inspect the remaining Limerick EDGs. Additionally, the licensee failed to determine if the nonconformance of the connecting rod bearings was acceptable.

d.

Should Discretion Be Exercised? Briefly explain: No, D21 represents the third known instance in which PECO improperly installed EDG connecting rod bearings.

PECO had the opportunity to identify the deficiency in D21, but failed to take adequate corrective actions following the discovery ofimproperly installed connecting rod bearings on D22 in May 1997.

• 6. Non-RoutineIssues/AdditionalInformation/ lessons Learned:

a. Is generic communication (IN, GL etc.) needed for this issue? No b. Is inspection or enforcement guidance needed? No Is there a need for NRR or NMSS programmatic guidance or interpretation of c.

requirements? No d. Are there any lessons learned? No Are these issues related to an allegation? No

e.

f.

Is there any other information about this case that should be considered and is important to note? No

1. 7. PanelDecision:

1. 8. Consistency with Previous Actions / Enforcement Guidance:

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