ML18037A881

LER 94-003-00:on 940104,standby Gas Treatment Trains Declared Inoperable as Result of Inoperable Edgs.Caused by Fuel Oil Leak.Tripping Time Relay Replaced & Testing ongoing.W/940510 Ltr

ML18037A881
Person / Time
Site:	Browns Ferry
Issue date:	05/10/1994
From:	Hsieh C, Machon R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-003-02, LER-94-3-2, NUDOCS 9405180057
Download: ML18037A881 (20)

Text

ACCELERATED DIRIBUTION SYSTEM DEMONSTRATION REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9405180057 DOC.DATE: 94/05/10 NOTARIZED: NO DOCKET FACIL:50-260 Browns-Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH. NAME AUTHOR AFFILIATION HSIEH,C.S. Tennessee Valley Authority MACHON,R.D. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 94-003-00:on 940104,standby gas treatment trains declared inoperable as result of inoperable EDGs.Caused by fuel oil leak. Tripping time relay replaced & testing D ongoing.W/940510 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES D

. ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-4-PD 1 1 TRIMBLE,D 1 1 D INTERNAL: ACRS 1 1 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DE/EELB 1 1 NRR/ DE/EME B '1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 NRR/DS8~. LB 1 1 NRR/DSSA/SRXB 1 1 E~gliE 02 1 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 '1 NSIC MURPHY,G.A 1 1 NSIC POORE,W.. 1 1 NUDOCS FULL TXT 1 1 D

D D

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT COiNTROL DESK, ROOiVI P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 28 ENCL 28

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Tetmssee Vasey Au,ronty. Post Office Box.2000, Demtu;, Atabarna 35609.2000

.R. D. (Rick) Machon Vrce Pres'cent, Bro vns Ferry Nuctea. Ptant NY i 0 1994 U.S. Nuclear Regulatory Commission 10 CFR. 50.73 ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

BROWNS FERRY NUCLEAR PLANT (BFN) UNITS 1i 2i AND 3 DOCKET NOS. 50-259i -

50-260'ND 296 FACILITY OPERATING LICENSE DPR-33i 52'ND 68 - LICENSEE EVENT REPORT (LER) 50-260/94003 The enclosed LER provides details concerning a January 4, 1994 event where two of the three Standby Gas Treatment system trains were declared inoperable as a result.

of unrelated problems with thei.r'mergency diesel generators.

TVA initially determined that this event was not reportable based'n the guidance contained in NUREG-1022 and its supplements. As discussed in TVA's April 13, 1994, letter, "NRC Inspection Report 50-259, 50-260, 50-296/94-01 Reply to Notice of Violation," TVA has agreed to report this with event.

Accordingly, this -report is submitted in accordance 10 CFR 50.73(a) (2)(v)(D).

Sincerely, R. . Machon Site Vice President PAB 1E-BFN Enclosure cc: See page 2 9405180057 940510 PDR ADOCK 05000260 S PDR

0 U.S. Nuclear Regulatory Commission Page 2 NN I0 1994 cc (Enclosure):

INFO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 Paul Krippner American Nuclear Insurers Town Center, Suite 300S 29 South Main Street West, Hartford, Connecticut 06107 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Regional Administrator U.S. Nuclear Regulatory Commission Region 101 II Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. D. C. Trimble, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

NRC FORH 366 U.S. NUCLEAR REGULATORY CCSOIISSION APPROVED BY OHB NO. 3'!50-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE . TO COHPLY WITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS.

LXCENSEE EVENT REPORT (LER) FORWARD COHHENTS REGARDING BURDEN ESTIHATE TO THE INFORHATION AND RECORDS HANAGEHENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION, (See reverse for required nunber of digits/characters for each block) WASHIHGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT <3140.0104), OFFICE OF HANAGEHENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAHE Browns (1)

Ferr Nuclear Plant BFN Unit 2'OCKET NNBER 05000260 (2) 1 OF PAGE 7

(3)

TITLE (4).Standby Gas Treatment Trains Declared Inoperable as a Result of Inoperable Emergency Diesel Generators EVENT DATE 5 LER HINBER 6 REPORT DATE 7 OTHER FACILITIES INVOLVED B SEQUENTIAL REVISION FACILITY HAHE DOCKET NUhfBBR HONTH DAY YEAR YEAR HOHTH DAY YEAR HUHBER HUHBER FACILITY NAHE DOCKET NUHBER 01 04 94 94 003 00 05 10 OPERATING THIS REPORT IS SUBHITTED PURSUANT TO THE REQUIREHENTS OF 10 CFR  : Check one or mor e 11 NODE (9) N 20.402<b) 20.405(c) 50.73(a)(2)(iv) 73.71(b)

POWER 20.405(a)(1)(i) 50 '6(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL (10) 1OO 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) (Specify in 20.405(a)(l)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstract and in Text, below 2D.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A LICENSEE CONTACT FOR THIS LER 12 HAHE TELEPHONE NUHBER (Include Area Code)

Clare S. Hsieh, Compliance Licensing Engineer (205) 729-2635 C(SIPLETE ONE LINE FOR EACH COHPOHENT FAILURE DESCRIBED IN THIS REPORT 13 REPORTABLE REPORTABLE CAUSE SYSTEH COMPONENT HANUFACTURER CAUSE SYSTEH COHPONENT HAHUFACTURER TO NPRDS TO NPRDS X EK A500 EK PSF G100 SUPPLEHEHTAL REPORT EXPECTED 14 EXPECTED HONTH 'AY YEAR YES SUBH I SS I ON (If yes, complete EXPECTED SUBHISSION DATE).

X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten'ines) (16)

On January 4, 1994, at 0634 hours0.00734 days <br />0.176 hours <br />0.00105 weeks <br />2.41237e-4 months <br /> Central Standard Time (CST), TVA declared the Unit 1/2

'A'mergency Diesel Generator (EDG) inoperable as a result of a fuel oil leak. At 1940 hours0.0225 days <br />0.539 hours <br />0.00321 weeks <br />7.3817e-4 months <br /> CST, the Unit 3 'D'DG was declared inoperable due to a failed timing relay. With these two EDGs being simultaneously 'inoperable, TVA also declared the 'A'nd 'C'tandby Gas Treatment. (SBGT) trains inoperable per the plant's Technical Specificati.ons (TS)'. The Limiting Condition for Operation (LCO) of the TS required the Unit to restore one of the SBGT trains to operable status or be in hot standby within six hours. At 2025 hours0.0234 days <br />0.563 hours <br />0.00335 weeks <br />7.705125e-4 months <br />, TVA restored the 3 'D'DG and the 'A'nd 'O'BGT trains to operable status, and the six-hour LCO action was exited. Following appropriate corrective maintenance, the 1/2 'A'DG was restored to operable status on January 6, 1994.

The fuel oi.l leak on the 1/2 'A'DG resulted from a cracked brass nipple in the diesel

'D'DG was due engine driven fuel pump piping. The fai.lure of the 'timing relay on the 3 to a bent lead on its integrated circuit chip; TVA performs a monthly operabi.lity test on each 'EDGI which checks for any leakages and damages. No similar oil leaks were observed on the other EDGs, and no similar ni.pple failures have been found from maintenance history search; therefore, no 'A'DG. further action is necessary to prevent recurrence of the problem associated with the 1/2 Concerning the problem associated with the 3 'D'DG, TVA will inspect other similar type timing relays. This event is similar in nature to LERs 259/86026 and 259/86036.

On April 12, 1994, TVA concluded that this event was reportable per 10 CFR 50.73 (a)(2)(V)(D).

NRC FORM 366A U.S. NUCLEAR REGULATORY CONIISSION APPROVED BY (NB NO. 3150-0104 (5 92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPOHSE TO COMPLY WITH THIS INFORMATION COLLECTION REOUEST: 50.0 HRS. 'FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE IHFORMATI OH AND RECORDS MANAGEMENT LICENSEE EVENT REPORT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, TEXT CONTINUATION WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTIOH PROJECT (3150-0104), OFFICE OF MANAGEHEHT AND BUDGET, WASHINGTON DC 20503 FACILITY NAME (1) DOCKET HIER (2) LER HINIBER (6) PAGE (3)

YEAR SEOUENTIAL REVISION NUMBER NUMBER 2of.7 Browns Ferry Unit 2 05000260 94 003 00 TEXT If more s ce is r ired use edditionsI co ies of NRC Form 366A (17)

I ~ PLANT CONDITIONS Unit 2 was at approximately 100 percent power (3293 megawatts thermal).

Units 1 and 3 were shutdown and defueled.

II'ESCRIPTION OF EVENT A. Event; On April 12, 1994, TVA concluded that an event that resulted in two of the'three trains of the Standby Gas Treatment (SBGT) (HF]

system being declared inoperable was reportable as a condition that alone could have prevented the fulfillment of a safety function needed. to mitigate the consequences of an accident (10 CFR 50.72 (b)(2)(iii)(D)'nd 10 CFR 50.73 (a)(2)(v)(D)).

Initially, TVA'valuated this event and determined that was not reportable (Reference TVA letter, dated April 13, 1994, "NRC it Inspection Report 50-259, 50-260, 50-296/94-01 Reply To Notice of Violation" ). The specifics of this event are provided below:

On January 4, 1994, at 0634 hours0.00734 days <br />0.176 hours <br />0.00105 weeks <br />2.41237e-4 months <br /> Central Standard Time (CST), the Unit 1/2 'A'mergency Diesel Generator (EDG) (EK] was declared inoperable due to a fuel oil leak at the engine driven fuel oil pump. Corrective maintenance was initi.ated to repair the fuel oil leak. Per BFN Technical Specifications (TS) 1.C.2', the 'A'rain SBGT, which receives its emergency power supply from 1/2 'A'DG, was not declared inoperable since its offsite power source and the other two SBGT trains ('B'nd 'C') were operable.

At 1615 hours0.0187 days <br />0.449 hours <br />0.00267 weeks <br />6.145075e-4 months <br />, an Assistant Unit Operator (AUO) (utility, unlicensed) discovered a tripped relay target on the timing delay breaker closing relay [RLY]'or the Unit 3 'D'DG (this EDG provides emergency power supply to the 'C'BGT train). The TS 1.C.2 states, "when a system, subsystem, train, component, or device is determined to be inoperable solely because its onsite power source is inoperable, or solely because its offsite power source is inoperable, it may be considered operable for the purpose of satisfying the requirements of its applicable LCO provided: 1) its corresponding offsite or diesel power source is operable; and 2) all of its redundant system(s), subsytem(s), train(s), component(s) and device(s) are operable, or likewise satisfy these requirements."

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NRC FORM 366A U.S. WCLEAR REGULATORY CQIIISSION APPROVED BY QNI NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COMPLY NITH THIS INFORMATION COLLECTION REQUEST: 50.0 MRS. FORNARD COMMENTS RE'GARO ING BURDEN ESTIMATE TO THE INFORMATION AMD RECORDS HANAGEHENT LICENSEE EVENT REPORT BRANCH (HMBB 7714), U.S. NUCLEAR REGULATORY COMMISSION,

.TEXT CONTINUATION NASHIMGTON, DC 20555-0001, AND TO THE PAPERMORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AMD BUDGET, UASHINGTON, DC 20503 FACILITY NAME (1) DOCKET NWBER (2) LER NIMSER (6) PAGE (3)

YEAR SEOUENTIAL REVISION NUMBER NUMBER 3 of 7 Browns Ferry Unit 2 05000260 003 00 TEXT If more s ce is r ired use additional co ies of NRC Form 366A (11')

operator attempted to reset the relay target, but the target retripped. The Unit 3 Assistant Shift Operations Supervisor (ASOS) (utility, licensed) verified the relay target would not reset.

At 1645 hours0.019 days <br />0.457 hours <br />0.00272 weeks <br />6.259225e-4 months <br />, the Unit 3 ASOS notified the plant Technical Support personnel and the SOS (utility, licensed) of the condition. The Technical Support personnel initiated the troubleshooting of the tripped relay target to determine 'the cause of its failure to reset. After inspecting the triped relay target, checking the EDG's breaker anti-pump logic, and reviewing the appropriate vendor manuals and drawings, it that the relay's reset failure would impair the ability of the EDG was determined to operate, if so needed. The Technical Support personnel promptly conveyed this information to the operators.

At 1940 hours0.0225 days <br />0.539 hours <br />0.00321 weeks <br />7.3817e-4 months <br />, based on the above information, the operators declared 3 'D'DG inoperable. Due to the EDGs for the 'A'nd

'O'BGT being simultaneously inoperable, the conditions of TS 1.C.2 were no longer satisfied. Thus) operators also declared the

'A'nd- 'O'= SBGT trains inoperable, and entered the Limiting Condition for Operation (LCO) for TS 1.C.2 and 3.7.B, "Standby Gas Treatment System." TS 1.C.2 LCO was the most restrictive, which required the Unit to either satisfy the conditions of this, TS or place the Unit in Hot Standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. (Note: TS 1.C.2 is not. equivalent to Standard TS 3.0;3).

At 2025 hours0.0234 days <br />0.563 hours <br />0.00335 weeks <br />7.705125e-4 months <br />, the tripped relay for the 3 'D'DG was replaced.

This resulted in the condition of TS 1.C.2 being satisfied, and the 'A'nd 'O'BGT trains were declared operable. On January 6, 1994, after completing the appropriate maintenance, TVA returned the 1/2 'A'DG back to service.

TS Basis 3.7.B/3.7.C states that two of the three SBGT trains are needed to clean up the reactor building atmosphere upon contai.nment isolation. Even though the 'A'nd 'O'BGT trains were restored to operable status within the allowable TS LCO, was determined that this event had the potential to prevent the it fulfillment of a safety function needed to mitigate the consequences of an accident. The analysis in section IV of this report describes why this potential was highly unli.kely.

The time delay relay performs a safety related function by preventing the actuation of the EDG breaker anti-pump logic; thus, preventing the subsequent lockout of the EDG breaker.

Oi HRC FORM 366A U.S NUCLEAR REGUUlTORY CQIIISS ION APPROVED BY QNI HO. 3150-0104 (5-92) EXP I RES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMEHTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT LICENSEE EVENT REPORT BRANCH (HHBB 7714), U.S. NUCLEAR REGULATORY COMMISSIOH, TEXT CONTINUATION WASH I HGTON ~ DC 20555 0001 ~ AND TO THE PAPERWORK REDUCT ION PROJECT (3150-0104), OFFICE OF MANAGEHEHT AND BUDGET, WASHINGTON, DC 20503 FACILITY NAME (1) DOCKET'IHIBER (2) LER HU{BER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUMBER NUMBER 4 of 7 Browns Ferry Unit 2 05000260 94 003 00 TEXT If more s ee is r uired use additional co les of NRC Form 366A (17)

B. Ino erable Structures Cpm onents or S stems that Contributed to the Event:

None.

C. Dates and A roximate Times of Ma'or Occurrences:

January 4, 1994 at 0634 CST Declared the 1/2 'A'DG inoperable; started the corrective maintenance to fix the fuel oil leak.

1615 CST Discovered the tripped timing relay target; attempts to reset the target were unsuccessful.

1940 CST Declared the 3 'D'DG and the 'A' trains inoperable; entered affected 'C'BGT TS LCOs.

2025 CST Replaced the tripped timing relay; declared the 3 'D'DG and the 'A'c trains operable; and exited affected 'C'BGT TS LCOs.

January 6, 1994 Completed appropriate maintenance on the 1/2 'A'DG; returned 1/2 'A'DG back to service.

April 12, 1994 at 1339 Central A four-hour nonemergency notification was Daylight made to NRC in accordance with 10 CFR Savings 50.72 (b)(2)(iii)(D) ~

Time D. Other S stems or Seconda Functions Affected!

None.

E. Method of Discove A reactor building AUO discovered the tripped timing relay target during plant walkdown. The fuel oil leak was discovered during the 1/2 'A'DG monthly operability test.

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NRC FORH 366A U.S. IN)CLEAR REGULATORY IXNNIISSION APPROVED BY INB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEH PER RESPONSE TO COMPLY WITH THIS INFORHATION COLLECTION REQUEST: 50.0 NRS. FORWARD COHHENTS REGARDING BURDEN EST IHATE TO THE IHFORHATION AND RECORDS HANAGEHENT, LICENSEE EVENT REPORT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION, TEXT CONTZNUATZON WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF HANAGEHENT AND BUDGET, WASHINGTON, DC 20503 FACILITY HAHE (1) DOCKET HQLSER (2) LER NWBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUHBER NUHBER 5 of 7 Browns Ferry Unit, 2 05000260 94 003 00 TEXT If more s ce is r ired use odditionel co ies of NRC Form 3 66A (1)')

F. 0 erator Actions!

No operator actions were required or needed for this event.

G. Safet S stem Res onsest None.

ZZZ. CAUSE OF THE EVENT A. Immediate Cause:

This event was caused by two factors: 1) The engine driven fuel oil pump on the 1/2 'A'DG had an failed oi.l leak, and 2) the 3 'D'DG to reset.

timing delay breaker relay target B. Root Cause:

The fuel oil leak on the 1/2 'A'DG resulted from a cracked brass nipple in the diesel engine driven fuel pump piping. The brass nipple was examined. No abnormalities could be found) thus, the crack was an isolated failure of the nipple.

The failure of the timing relay on the 3 'D'DG was due to a bent lead i.n its Integrated Circuit (IC) chip for the relay's Divide-by-"N" counter. This most likely occurred during relay assemblage. Over a period of time, the bent lead prevented the counter from being properly connected to the time delay circuit and resulted in the 'relay target failure to reset.

C. Contributin Factors:

None.

IV+ ANALYSIS OF THE EVENT The safety function of the SBGT for postulated accidents'uring plant operation is to limit leakage from the secondary containment to below acceptable levels (i.e., 10 CFR 100 levels). The SBGT performs this safety function by maintaining the secondary containment at a negative pressure, which ensures that radioactive releases are made through the SBGT.

If an accident occurred requiring operation of the SBGT, the secondary containment would have been at a negative pressure, si.nce the secondary containment is maintained that way during operation. One train of the SBGT system with a capacity of 9,000 scfm +/- 10 percent would have

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NRC FORM 366A U.S. NUCLEAR REGULATORY CQOIISS ION APPROVED BY (WS NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS. FORWARD COHHENTS REGARDING BURDEN ESTIHATE TO THE INFORMATION AND RECORDS HANAGEHENT LICENSEE EVENT REPORT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION, TEXT CONTINUATION WASHINGTON, DC 20555 0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF HANAGEHENT AND BUDGET, WASHINGTON DC 20503 FACILITY NAME (1) DOCKET M(NIGER (2) LER NWBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUMBER NUMBER 6 of 7 Browns Ferry Unit 2 05000260 003 00 TEXT if more s ce is r uired use edditions( co i s of NRC Form 366A (17) automatically started. Operators could have promptly restored power from other electrical boards to one or both of the trains by using switches in the contxol room. For example, operators could have started 'A'BGT train by means of transferring the 'A'80V Diesel Auxiliary Board to the 'B'KV Shutdown Board (the 'B'oard is tied to the 1/2 'B'DG). Procedural guidance'xists for operators to perform this operation from the control room. Additionally, the capability to transfer power supplies between EDGs is within the design basis of the plant.

During the short period of time that the EDGs were inoperable (i.e.,

approximately 45 minutes), offsite power source was maintained and three SBGT trains were functional. Additionally, based on the it is unlikely that this event would have resulted in a loss of safety function for the SBGT for the duration that the EDGs were above'nalysis, inoperable. Therefore, this event did not adversely affect the health and safety of plant personnel or the public.

CORRECTIVE ACTIONS A. Immediate Corrective Actions:

Upon discovery of the problems associated with, each of the EDGs, TVA immediately initiated corrective actions. The tripped timing relay was replaced, and the 3 'D'DG was restored to operable status at 2025 hours0.0234 days <br />0.563 hours <br />0.00335 weeks <br />7.705125e-4 months <br /> on January 4, 1994. The appropriate maintenance was completed on the 1/2 'A'DG, and the 1/2 'A'DG was restored to operable status on January 6, 1994.

B. Corrective Actions to Prevent Recurrence:

Monthly operability testing is performed on each EDG. During this operability test, the EDG system is checked for any leakages or damages. No similar oil leaks were observed on the other EDGs, and no similar nipple failures were found from maintenance history search; therefore, no further corrective actions are needed regarding the EDG fuel oil leak event.

Regarding the relay failure event, there are seven other relays of this type installed in the plant and have been in service approximately six years. Prior to this event, EDG timing delay breaker relays have been performed satisfactory and have passed normal surveillance calibration. However, as a result of this event, TVA will inspect other similar type timing relays as part of their next scheduled surveillance calibration.

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NRC FORN 366A U.S. NUCLEAR REGULATORY (XHS(ISSION APPROVED BY (N8 NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPOHSE TO CONPLY WITH THIS IHFORHATION COLLECT I OH REQUEST: 50 ~ 0 HRS. FORWARD COHHEH'TS REGARDING BURDEN EST IHATE TO THE IHFORHATION AND RECORDS HAHAGEHEHT LICENSEE EVENT REPORT BRANCH (NHBB 771C), U.S. NUCLEAR REGULATORY 'COHHISSIOH, TEXT CONTINUATION 'WASHINGTON, DC 20555-0001, AHD TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF HAHAGEHEHT AND BUDGET, WASHINGTON DC 20503 FACILITT NAHE (1) DOCKET NOSER (2) LER IRR(BER (6) PAGE (3)

TEAR SEQUENTIAL REVISION NUNBER NUHBER 7 of 7 Browne Ferry Unit 2 05000260 003 00 TEXT lf more s ce is r ired use additional co les of NRC Form 366A (17)

VI ~ ADDITIONAL INFORMATION A. Failed Cpm onentst 1/2 inch Brass Nipple from 90 degree Elbow Piping {Material: P61 brass ASTM B43 Temper)

Timing Relay 3-02-211-1836A, Type No. ITE 62T, Manufacturer by ASEA Brown Boveri B. Previous LERs on Similar Events:

There were no previous similar events, of this type of relay

,failure. However, there were two previous events that involved the SBGT trains being declared inoperable as a result of inoperable EDGs.

259/86026 On July 24, 1986, while operating the unit 1/2

'D'DG to maintain its oil temperature, a mechanical overspeed trip occurred. The 1/2 also out of service at the time for

'A'DG was maintenance. This left with only one of three SBGT trains operable.

259/86036 - On December 8, 1986, with 1/2 'D'DG out of service for maintenance, 1/2 'A'DG was declared inoperable during the performance of the monthly surveillance instruction.

Additionally, Residual Heat Removal {RHR) heat exchanger 3 'C'as mistakenly removed from service at .same time.

The 259/86026 event was reported as a condition prohibited by the plant's TS. The 259/86036 event was reported as a condition that resulted in the plant being in an unanalyzed condition that significantly compromised plant safety due to the inoperability of the SBGT trains and RHR heat exchangers.

VII. Commitments TVA will inspect other similar type timing relays by July 30, 1995 as part of their next scheduled surveillance calibration.

Energy Industry Identification System. {EIIS) system and component codes are identified in the text with brackets {e.g., {XX)).

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