ML17345A180

LER 88-004-00:on 880408,Tech Spec 3.5-2,Item 3.2.b Exceeded. Caused by Failure of Relays in Undervoltage Protection Scheme.Relays Replaced & Satisfactorily Tested Before Unit Shutdown Commenced

ML17345A180
Person / Time
Site:	Turkey Point
Issue date:	05/09/1988
From:	Hart R FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17345A181	List: ML17345A180 ML17345A182
References
LER-88-004-03, LER-88-4-3, NUDOCS 8805310057
Download: ML17345A180 (4)

Text

U.S. NVCLKAR AKOULATOAYCOMMISSION NAC Form 344 (943) APPROVED OMS NO, 315OOIOI EXPIRES: 4I31 IBS LICENSEE EVENT REPORT (LER)

DOCKET NUMBER (2) PA E 3 FACILITY NAME 0) urke Point Unit 4 0 5 0 0 0 1 OF ac nrca Oacr rca ron c ron a oman ~xcee a 0 Undervol tage Relay Failed During Periodic Testing EVENT DATE (5) LER NUMBER (4) A E PORT OAT E (7) OTHER FACILITIES INVOLVED (SI YEAR SKOVSNTrAL RKvtaroN MONTH DAY YEAR FACILITYNAMES DOCKET NUMBER(S)

MONTH OAY YEAR NVMSKR NVMSKR 0 5 0 0 0 OPEAATING 004 0 0 05088 THIS AEPORT IS SUBMITTED PURSUANT 7 0 THE AEOUIREMKNTS OF 10 C FR ('I: ICnec>> one or more of the follorffnol (11) 0 5 0 0 0 MODE (9) 20A02(S) 20AOS(cl 50.73(e) (2) (iv) 73.7((S)

POWER 20A05 ( ~ I (I) I I) 50.34(cl (I) 50.734H2Hv) 73.71(c)

LEY EL 50.34(cl(2l 50.734) I2)(vBI OTHER (Specify in Aettrect 1 p p 20 AOB(~ l(1 I (4)

Oelovr encl In Text, AIIIC Form 20AOB( ~ l(1)(BII 50.73(al(2HI) 50.734) (2)(viii)(A) 344A) 20A054)(l l(iv) 50.73(e I (2 I I III 50.73(eH2)(viiiHS) yw',o.i 7KF7g7r(My4$ 20AOS(e I (I Hvl 50.73(e l(2) (iiil 50.73(el(2Hxl LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AAEA CODE Randall D. Hart, Licensing Engineer 305 24 6-6 55 9 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OKSCRISED IN THIS RKPOAT (13)

MANUFAC.

N~S MANUFAC. COMPONENT 9'O CAUSE SYSTEM COMPONENT TURER TUAER N'ADS Pja@YP. K4 X J E RLY G 0 8 NWP X J E RLY G 0 8 NI&

SUPPLKMENTAL REPORT EXPECTED (Iel EXPECTED MONTH DAY YEAR SUBMISSION DATE (15)

YKS llfyet, complere EXPECTED SUSMISSIOH DATEI NO ABSTRACT (Limit to teOO tpecet, I.e., approximately fifteen afnOleepece typevrrltten lineal (I ~ )

On April 8, 1988, the requirements of Technical Specification (TS) Table 3.5-2, item 3.2.b were exceeded. During the performance of operating procedure (OP) 9404.2, 4160 volt and 480 volt switchgear - undervoltage test, the undervoltage protection circuit for the 4A 480 volt load center would not pass the test. This channel was declared out of service and maintenance was requested to investigate the failure . TS section 3.5, Table 3.5-2, item 3.2.b requires that for the 480V load centers, power operation may continue with one channel inoperable as long as the inoperable channel is placed in the tripped condition. Operations was unable to place the channel in the tripped condition. Therefore, the requirements of TS Table 3.5-2, item 3.2.b could not be met and Unit 4 was required to be placed into TS 3.0.1 which requires the unit to be in hot standby in 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />. Maintenance replaced relays 327TX/4A1 and 327TX/4A2, OP 9404.2 was recommenced and the replaced relays were satisfactorily tested . This took the unit out of TS 3.0.1. The cause of the event was failure of relays 327TX/4Al and 327TX/4A2 in the undervoltage protection scheme for the 4A 480 volt load center. FPL s Engineering Department has been requested to evaluate this failure to determine root cause and appropriate corrective actions .

8805310057 88O50'0 PDR ADOCK 0500o25i S PDR NRC Farm 344 (943 I

NRC Form 3ddA US NUCLEAR REGULATORY COMMISSION 18431 LICENSEE E ENT REPORT (LER) TEXT CONTINUA N APPROVEO OMB NO. 3150M(04 EXPIRES: 8/31/88 FACILITYNAME (1l OOCKET NUMBER (3(

LER NUMBER (dl PAGE (3)

VE'AR SEGUENTIAL REVISION NUMBER NUMBER Point Unit 4 2 5 1 8 8 0 0 4 00 02

'urkey 03 0 s 0 0 s oF TEXT ///moro EI>>ea/E roqrrinrd, rr>> oddrr/ar>>/NRC Form 38843/(17)

EVENT:

On April 8, 1988, the requirements of Technical Specification (TS) Table 3.5-2, item 3.2.b were exceeded . At 1410 during the performance of operating procedure (OP) 9404.2, 4160 volt and 480 volt switchgear undervoltage test, the undervoltage protection circuit for the 4A 480 volt load center would not pass the test. The red indicating light did not come'n as required by the procedure . This channel was declared out of service and the Electrical Maintenance Department was requested to investigate the occurrence . They discovered that relays 327TX/4A1 and 327TX/4A2 had failed.

The circuit in which these relays are used utilizes a two-of-two logic to enable a non-safety in)ection degraded voltage trip received by both 327/**>

relays (General Electric inverse-time type relay model IAV55C). Since this relay failed in an open-circuited condition (coil burned out), the trip position for that portion of the circuit could not be applied . While the IAV55C degraded voltage relay has provisions to place it in the trip mode via shorting bars to create a one-of-one trip logic scheme, no similar provision exits for the 327TX/4A1 and 327TX/4A2 auxiliary relays downstream in the circuit.

TS section 3.5, Table 3.5-2 (Engineered Safety Features Actuation), item 3.2.b requires that for the 480V load centers, power operation may continue with one channel inoperable as long as the inoperable channel is placed in the tripped condition . Since the design of the circuit does not allow the affected relays to be placed in the tripped condition, continued operation of Unit 4 was prohibited by TS Table 3.5-2, item 3.2.b. This placed Unit 4 into'S 3.0.1, which required the unit to be in hot standby within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> . Electrical Maintenance replaced relays 327TX/4Al and 327TX/4A2, OP 9404.2 was recommenced and the replaced relays were tested satisfactorily at 1650. This took the unit out of TS 3.0.1.

CAUSE OF EVENT:

1 The cause of the event was a failure of relays 327TX/4Al and 327TX/4A2 in the undervoltage protection scheme for the 4A 480 volt load center and the inability to place the failed relay into the tripped condition to meet TS action statement requirements. These relays failed due to an open circuited coil. The cause of the relay failure is still under investigation by power plant engineering. The preliminary investigations have not identified any clear failure mechanism for the failed relays.

NRC FORM SddA (8831

drRc Form 344A (NI3( NUCLEAR REOULATORY COMMISSION LICENSEE NT REPORT (LER) TEXT CONTlNU N APPROVEO OM4 NO. 3150W104 EXPIRESI 4/3I/44 F*CIL(TY NAME tll OOCYTE T NUMEER IEI LER NUMEER (El PACE (3I YEAR SEQUENTIAL rr E v rs Io N NUMEER NI/M ER P int Unit 4 0 5 0 0 0 OF TEXT /I/ moro IPoco rf rNRrrod, rrw fddd/ooo/ HRC Fonrr 36644/ llT(

ANALYSIS OP EVENT:

Upon identification of the failure, the affected relays were replaced and returned to service before a unit shutdown was commenced. FPL s Engineering Department has been requested to evaluate this failure to determine root cause, appropriate corrective actions and the safety significance of this event.

Should this evaluation significantly change the information provided in this LER, a LER update will be sent accordingly.

CORRECTIVE ACTIONS:

1) Relays 327TX/4Al and 327TX/4A2 were replaced and satisfactorily tested before a unit shutdown was commenced.

2) FPL s Engineering Department has been requested to evaluate this concern to assist in identifying the root cause and appropriate corrective'actions. This effort will proceed in accordance with the Integrated Schedule (IS). This schedule for completion is currently being reviewed to determine if enhancements can be made .

ADDITIONAL DETAILS:

The affected relay is manufactured by General Electric and is model number CR120BD04341 ~

Similar Occurrences: LER 251-87-013 reported a similar failure of a 480 volt load center undervoltage relay on the 4C 480 volt load center NRC FORM 344A (943(

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