ML20012D813

LER 90-003-00:on 900223,discovered 16 Transformer Core Clamp Bolts Missing on Seismically Qualified Switchgear. Caused by Installation Error During Const Phase of Plant. Missing Clamps replaced.W/900323 Ltr

ML20012D813
Person / Time
Site:	Vogtle
Issue date:	03/23/1990
From:	Hairston W, Odom R GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ELV-01446, ELV-1446, LER-90-003-01, LER-90-3-1, NUDOCS 9003280397
Download: ML20012D813 (5)

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[4 2(U Goo'0'a Power Company -

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Manta, George 30308 '

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.Maeleng Addressi .

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Post Office Box 1295 '

. BirmingNim. Alabama 35201:-

[i- . Te4 phone 205 000 55a1 March 23, 1990; ve'en t**c emm W. O. Hatrston, til Senior Vee President ,  ;

Nuclear Operations -

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ELV-01446 0300 ,

'DocketL No.- 50-424

- U. S.- Nuclear. Regulatory Commission

-ATTN: Document Control Desk i.

-Washington,.D. C.- 20555 .

- Gentlemen:-

V0GTLE ELECTRIC GENERATING PLANT LICENSEE EVENT REPORT - -

MISSING SEISMIC BOLTS ON TRANSFORMER LEADS TO UNIT SHUTDOWN

In accordance with 10 CFR 50.73, Georgia Power Company hereby submits the i enclosed ' report related' to an event which occurred on February 23, 1990.

-Sincerely, l . h.blk l? W. G.-Hairston, III l ..

WGH,III/NJS/gm -

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Enclosure:

. LER .50-424/1990-03 i

L =xc: 'Georaia Power Comoany H Mr. C. K. McCoy p

Mr. G. Bockhold, Jr.

Mr. R.1M. Odom l- 'Mr. P. D. Rushton L NORMS l ' M. S. Nuclear Reaulatory Commission l- Mr.' S. D. - Ebneter, Regional Administrator l

Mr. T.'A. Reed, Licensing Project Manager, NRR

- 3 p Mr. R. F. Aiello, Senior Resident Inspector, Vogtle 7;

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s LICENSEE EVENT REPORT (LER)

! F ACILITV NAM 4111 DOCKET NUMBE R (21 PAGE (3a V0GTLE ELECTRIC GENERATING PLANT- o is Io Io Iol4 214 1 1 lorl 014 flTLE (45 MISSING SEISMIC BOLTS ON TRANSFORMERS LEAD TO UNIT SHUTDOWN

- EVENT DATE (St LER NUMSE R 16) REPORT DATE (7) OTHE R F ACILITIES INVOtVED (8)

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Ol2 2l 3 90 9l0 0l0l3 0l0 o-l3 . 2 l3 9l0 0 1 5 1 0 tofoi l I p,g g THis stEPORT 16 EveMITTED PUR$UANT TO THE REQUIREMENTS OF 10 CPR { (Chere o.e or more OF ,** fellowmfl (11)

MODE W 1 20 402161 to 406tel 60.73teH2Hivl 73 7116)

R 20 406(eH1Hil 50 34teHit 60 T3teH2Hel 73.71(el 20 406teH1Het 60.36tell21 50 731eH2Husil HE A6 f oc 1104 l l _

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CAUSE SYSTEM COMPONENT Mj)N',[ " foOHT pR S CAUSE SYSTEM COMPON E NT "h C- R ORfA LE o pp g l

! I i l 1 l l I I l l l 1 l I I I I I I I I i l i i l i SUPPLEMENTAL REPORT EXPECTED iter MONTH DAY YEAR I' SUSMt$$ ION YES 129 res ,emorerr EXPECTED SU0 MISSION DA TEl NO l l l

- A.1RAC1,-,,,,....,_..,.,..,v,..,.,....,,,.I On 2-23-90, a system engineer found 16 transformer core clamp bolts missing on seismically qualified switchgear. The switchgear was deenergized to replace the missing bolts which resulted in a Containment Isolation Valve (CIV) being deenergized at 1238 CST. After the four hour time period for reenergizing the valve had expired, unit shutdown was initiated as required by the Technical Specifications, Although the bolts were replaced and the CIV was reenergized i

before shutdown was completed, plant management elected to complete the shutdown L and enter into a planned refueling outage approximately four hours early, i

The cause of this event is attributed to an installation error during the construction phase of the plant. The missing clamp bolts were replaced and all similar transformers in Units 1 and 2 were inspected with no other bolts found to be missing, i.

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l F ACitle Y NAM 4 (11 - DOCKET NUMSER (2) LER NUMBER {$) PAGE (3) a ttg.a, ' Tf,p viaa -

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I A. . REQUIREMENT FOR REPORT This report is required per'10 CFR 50.73 (a)(2)(1) because a unit shutdown resulting from a-Technical Specification (TS) requirement was completed.

.B._ UNIT STATUS AT TIME OF EVENT At-the time of this event on 2-23-90, Unit I was operating in Mode 1 (Power Operation) at 88% of rated thermal power. The unit was in coastdown and preparations were underway for a refueling outage scheduled to begin at midnight the same day.

C. DESCRIPTION.0F EVENT On 2-23-90, a system engincar'was performing a cleanliness inspection of components of the 480 volt switchgear system. Using a flashlight, he was

.able to see. inside the casing vents of transformers 1AB04X and 1AB05X and found that their bottom core clamp bolts were missing. These bolts hold the transformer core to its casing and are necessary for the transformer's seismic integrity and' operability. The Shift Supervisor (SS) was advised and.switchgear IAB04,1AB05 and the associated busses were declared f' inoperable at 1128 CST. A Limiting Condition for Operation (LCO) was entered per TS 3.8.3.1. The action statement for this LC0 requires the inoperable train _ to he restored within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or the unit must be placed in Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Switchgear IAB04 was deenergized at 1238 CST so that the missing bolts could be replaced, which resulted in Containment Isolation Valve (CIV) 1HV-8112 being deenergized. The SS entered another LC0 for TS 3.6.3 at 1238 CST. ,

The action statement for TS 3.6.3 requires an inoperable CIV to be restored i L to operable status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, or the unit must be placed in Hot Standby I within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Work began to restore operability; however, after l 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, power reduction began. A Notification of Unusual Event (NUE) was i declared at 1655 CST as required by the VEGP Emergency Plan due to the I initiation of a unit shutdown required by the TS as a result of inoperable i Engineered Safety Features equipment, y

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010 013 oF 0 14 j TENT ## more spece Al reevroer, see asweenet NAC Form ARM's/ 41h ll By 1840 CST, the bottom core clamp bolts were installed in transformer .

LAB 04X, CIV IHV-8112 was restored to service and its associated LC0 was

-exited. At this point, unit shutdown was no longer required per TS 3.6.3.

However, the. LC0 for TS 3.8.3.1 was. still applicable and plant management elected to continue the shutdown process and enter the planned ~ refueling.

outage approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> ear.y. . The reactor was placed in Hot Standby at 1958 CST. The bottom core clamp bolts were installed on transformer

~1AB05X, the switchgear was reenergized, the LCO was exited and the NUE was-terminated at 2253 CST.  !

D. CAUSE OF EVENT ,

The cause of-this event is attributed to an installation error during the

, construction phase of the plant ~. It is speculated that the clamp bolts were incorrectly identified as shipping bolts that were removed during the installation process.

E. ANALYSIS OF: EVENT-Besides the CIV- previously mentioned, other loads which are powered by . -

switchgear IAB04 and 1AB05 include the Pressurizer Power Operated Relief Valve (PORV) Block Valve IHV-8000A, and the Train A Fuel Handling Building Post-Accident Ventilation System. Had a seismic event occurred, power may have.been lost to these loads. However, no such event has occurred since the operating license was received in 1987. Based on this consideration, there has been no' adverse impact on plant safety or public health and safety.

as a result of this event.

F .- CORRECTIVE ACTIONS

1. The 16 missing bottom core clamp bolts (8 per transformer) were replaced.

2. All ~similar transformers in Units 1 and 2 were inspected and no other bolts were found to be missing.

NRC FORM 364A *U.S. CPO 1988-52D 589 000 0

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.G. ADDITIONAL INFORMATION J

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1.- Failed Components:

None  ;

2. Previous Similar Events:

None-

3. Energy Industry Identification System Code:

5 Reactor Coolant System - AB Class- 1E 480' Volt Switchgear System'- ED Containment Isolation Control System ~- JM I Fuel Handling Building Post Accident Ventilation System - VC I

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