ML20132B329

Special Rept:On 961113,operator Discovered Control Switch for Diesel Output Breaker in pull-to-lock Position. Investigation Was Performed to Determine How Long Aac DG Was Inoperable

ML20132B329
Person / Time
Site:	Surry
Issue date:	12/06/1996
From:	Christian D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
96-610, NUDOCS 9612170144
Download: ML20132B329 (3)

Text

- - ._ . - .- .

lt 4

.. m . -

VIRGINIA ELECTHIC AND POWEH COMPANY RICHMOND, VIRGINIA 20061 Dered.er 6,1996 United States Nuclear Regulatory Commission Serial Number 96 610 Attention: Document Control Desk SPSLIC/JDK R0 Washington, D.C. 20555 Docket Nos. 50-280 50-281 j License Nos. DPR-32 DPR-37 Gentlemen: ,  !

VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 ALTERNATE AC SOURCE INOPERABLE SPECIAL REPORT Pursuant to Virginia Power Station Administrative Procedure VPAP-2802, " Notifications and Reports," a Special Report is being submitted because the Alternate AC (AAC)

Source, required t>y 10 CFR 50.63, did not meet all design commitments for an extended period. During this period, the ACC Diesel Generator was functional but may not have been able to accept loads within the committed time limit.

On November 13, 1996, operators were performing 0-MOP-AAC-001 " Removal from Service of the AAC Diesel Generator," to tag out the Alternate AC for maintenance. During the performance of the tag out, an operator discovered the control switch for the diesel ,

output breaker (05M4) in the Pull-To-Lock position. In this condition, the ACC Diesel Generator would start but the Generator Output Breaker would not automatically close on to the OM Bus. During a Station Blackout event, annunciators and procedures would have alerted operators to this condition and directed prompt actions to energize the bus.

In a May 10,1993 letter (Serial No.93-292), we committed that the AAC Diesel Generator would be available to accept loads within ten minutes of the operators determination that a Station Blackout condition exists. Further,in a June 28,1993, letter (Serial No. 93-292A),

we stated that the design allows the operator to energize the transfer busses manually j from the control room.

With the AAC Diesel Generator output breaker control switch in the Pull-To-Lock position, I)I j

)j a control room operator may not have been able to align the AAC Diesel Generator to the I transfer busses from the Main Control Room (MCR) within the required time limit.

Attachment 1 provides a simplified schematic of this electrical arrangement.

pO A review of the procedures associated with the AAC Diesel Generator was performed. The j procedures reviewed were those for removal from service, returning to service, and l

9612170144 961206 PDR ADOCK 05000280-S PDR

i

r l

A review of tne procedures associated with the AAC Diesel Generator was performed. The procedures reviewed were those for removal from service, returning to service, and  ;

j quarterly testing. The review identified that 0-MOP-AAC-002 Rev.1," Return to Service of '

the AAC Diesel Generator," did not return the AAC Diesel Generator output breaker control

)

! switch to the Auto-After-Trip position. Placing the control switch to the Pull-To-Lock '

position for the AAC Generator Output Breaker was incorporated into Revision 1, dated  ;

May 17,1996. A Procedure Action Request (PAR) was submitted and incorporated into 0-MOP-AAC-002, " Return to Service of the AAC Diesel Generator," to return the control

) switch to the Auto After Trip position on November 13,1996.

1 i

An investigation was performed to determine how long the AAC Diesel Generator was inoperable. The investigation determined that the AAC Diesel Generator became  :

j inoperable on September 17,1996, and remained in that condition until November 16,

]

1996, when the AAC Diesel Generator was returned to service using the corrected procedure. No other events were identified during the review.

Operator logs were revised to verify the position of control switches which could prevent

the AAC Diesel Generator from being able to load a bus. A Root Cause Evaluation was initiated to investigate this event. Recommendations from this investigation will be  ;

implemented as approved by Station Nuclear Safety Operating Committee (SNSOC). l This Special Report has been reviewed by the Station Nuclear Safety and Operating i Committee.

i j Should you have any questions regarding this report, please contact us, i

Very truly yours,

)

i D. A. Christian Station Manager, Surry Power Station I

! Attachment 1

cc

Regional Administrator 4

U.S. Nuclear Regulatory Commission Region 11 4

101 Marietta Street, N.W.

3 Suite 2900 Atlanta, Georgia 30323 i

Mr. R. A. Musser NRC Senior Resident inspector Surry Power Station

'. Attachment 1 o

• ~

Simplified Schematic IlusOM 34.5 KV 05M1

" ' ' - - Generator Output f3rcaker 05M3 05M4 R5KY 41M 480 -

480 04N11-1 ) )04 Nil-2

) } DIG Bus 01, IlusOMi ,

l i

05L1 05I.3 l i

To Emergency Bus "D" l

To Emergency Bus "E"