ML20237H365

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Rev 5 to Abnormal Operating Instruction AOI-21.5, Loss of 125-Volt DC Vital Battery Board I
ML20237H365
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 04/23/1987
From: Epperson J, Jacqwan Walker
TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20237H133 List: ... further results
References
AOI-21.5, NUDOCS 8708170166
Download: ML20237H365 (6)
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.I TENNESSEE VALLEY AUTHORITY r

SEQUOYAH NUCLEAR PLANT -

ABNORMAL OPERATING INSTRUCTION AOI-21.5 I -

LOSS OF 125V DC VITAL BATTERY

. BOARD I Unit 2 ,

Revision 5 j- '

PREPARED BY: J. R. Walker RESPONSIBLE SECTION: Operation's REVISED BY: Jeff Epperson

[- SUBMITTED BY: ,

,L c 1 Supervisor

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PORC Review: APR 2 31987 Date APPROVED BY: '

Plant Manager DATE APPROVED: PR23 M Reason for revision (include all Instruction Change Form Nos.):

Revised to correct annunciations and to move immediate actions to subsequent actions section.

The last page of this instruction is number: 4 1

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r. SEQUOYAH NUCLEAR PLANT PLANT'INSTRUCd' ION REVISION ' LOG -

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1 ABNORMAL OPERATING INSTRUCTION AOI-21.5-  !

REVISION. Date- Pages REASON FOR REVISION (INCLUDE COMMIT-LEVEL Approved Affected MENTS AND ALL ICF FORM NUMBERS) 1 11/06/79 All

! - ' 2- 12/17/80 1 3 07/22/83 All -

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4 07/31/84 f

1 Revised.to correct annunciations and to.

move immediate actions to subsequent 5 APRE 3.10A7 All actions section.

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" AOI-21.5 Page 1 of 4 Revis' ion'5 '

7 LOSS OF 125V DC VITAL BATTERY BOARD I .-

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I. SYMPTOMS A. Possible alarms l '.'

125V DC VITAL C:1ARGkR I FAILURE OR VITAL BATTERY I DISCHARGE.

2. 125V DC VITAL BATTERY BOARD I ABNORMAL.
3. 6900V SHUTDOWN BOARD 1A-A FAILURE OR BUS /NOPJ!AL FEEDER ^ 1 UNDERVOLTAGE OR OVERVOLTAGE (1-M-1).
4. 6900V SHUTDOWN BOARD.1A-A FAILURE OR BUS / NORMAL FEEDER UNDERVOLTAGE (0-M-26).
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5.

480V SHUTDOWN BOARD 1Al-A FAILURE 0R UNDERVOLT.tGE (1-M-1 and 0-M-26 6.

480V SHUTDOWN BOARD 1A2-A FAILURE OR UNDERVOLTAGE-(1-M-1 and 0-M-26

7. 6900V SHUTDOWN BOARD 2A-A FAILURE OR BUS / NORMAL FEEDER UNDERVOLTAGE OR OVERVOLTAGE (2-M-1).

E q' 8. 6900V SHUTDOWN BOARD 2A-A FAILURE OR BUS /NJAMAL FEEDER UNDERVOLTAGE (0-M-26).

9.

480V SHUTDOWN BOARD 2Al-A FAILURE OR UNDERVOLTAGE (2-M-1 and 0-M-26).

[ 10.

480V SHUTDOWN BOARD 2A2-A FAILURE OR UNDERVOLTAGE (2-M-1 L and 0-M-26).

B. Indications '

1.

Voltmeter on 1-H-1 and 2-M-1 indicates failure of 125V de bus I.

-2 . Ammeter on 1-M-1 and 2-M-1 for bus I battery shows zero.

3. Position indicating lights for auxiliary feedwater pump 2A-S will be out (located on panel 2-M-3).

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II_ AUTOMATIC ACTIONS A. All four diesel generators start but do not tie onto the shutdown boards.

III. IMMEDIATE OPERATOR ACTION .

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' A0I-21.5 Page ,2 of 4 Revision 5 IV. SUBSEQUENT OPERATOR ACTION -

A. Notify Assistant Shift Engineer (ASE) and Shift Engineer (SE)

B. Initiate REP per IP-1 (Engineered Safety Features) as required.

C. Have an inspection performed on 125V de vital BATTERY board I to de-

[ termine the cause of the failure. Try to restore voltage. Initiate

[ maintenance if necessary,.

D. Transfer turbine driven auxiliary feedwater pump 2A-S control circuit to f- alternate supply (located on local panel). ,

E. Transfer the following 125V dc buses to alternate feed.

CAUTION: When transferring the 125V de bus to alternate or back to normal, have someone hold the B.O. reset button pushed in located in panel 4 of 6.9kV logic panel 2A-A. This will prevent the B.O.

relays from going to a B.O. condition, which would sequence . -

the CCA, AFWP, ERCW, PZR heaters, and fire pumps if auto signal is present.

Xfer to Alt Return to Normal

! 1. 6.9kV shutdown board 2A-A backup bus.

2. 480V shutdown board 2Al-A l backup bus.  ;
3. 480V shutdown board 2A2-A backup bus.
4. 480V auxiliary building common board normal feeder.

F. Depending upon the amount of time required for restoring 125V de bus voltage, the diesel generators can be left running until restored or diesel generators 2A-A, 1B-B, and 2B-B can be stopped by the following procedure:

CAUTION: Coordinate this work with Unit 1 operator.

1. Place 43T(L) switch (located on diesel generator logic panel 1A-A) in TEST position and leave it in TEST.
2. Place all 43T(L) switches (located on diesel generator logic panels 2A-A, 1B-B, and 2B-B) in the TEST position simultaneously and then return thein to NORMAL.
3. Reset the emergency start lockout relays for diesel generators 2A-A, 1B-B, and 2B-B (located on each respective diesel generator relay panel in diesel generator building).

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-c SQN AOI-21.5 Page 3 of 4 Revision 5

  • r-' IV.

SUBSEQUENT OPERATOR ACTION (continued)-

F. 4.

Stop diesel generators 2A-A, 1B-B, and 2B-B by placing HS-82-74, HS-82-44, and HS-82-104 in the STOP position.

5.

Diesel generator 1A-A should be left running.

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[' Depending upon the cause of the failure or after repairs, voltage can be restored to the bus by placing the normal charger or 1-S spare charger in service or by. connecting the battery to the bus by closing breaker 107.

CAUTION:

If restoring voltage after a fault on the bus, use,a battery charger for energizing the bus if. possible.

{' NOTE:

( If board cannot be restored within two hours of loss, refer to Technical Specification 3.8.2.3.

H. After_ voltage is restored to the bus:

1.

Transfer the de buses back to norinal that were changed in step'IV.E of this procedure. Observe the same precautions (check off when normal).

2. Place 43T(L) switch (located on D.G. logic panel 1A-A) to NORMAL position.

3.

Reset then stoptheD.G.

emergency lA-A. start lockout relay for diesel generator lA-A; 4.

Return and 4. the diesel generators to their normal lineup by SOI-82.1, 2, 3, 5.

Transfer turbine driven auxiliary feedwater pump 2A-S control circuit back to normal.

V. REFERENCES A. Technical Specification 3.8.2.3 B. FSAR 8.3.2 C. Electrical Prints - 45N703-1 I. 45N703-5 45N724-1 45N749-1 45N749-2 45N765-3 45N765-4 45N767-5 45N630-2 45N630-3 '

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AOI-21.5 L

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Revision 5 VI. DISCUSSION '

This instruction ' covers the loss of 125V de vital battery board I voltage. This f..

Instruction assumes that Unit No. 2 is at power operation at the time of the event.

The other three vital battery boards remain in normal operation throughout the duration of this event. The unit can' remain at power operation with no

-[- I degradation of the unit safgty related systems. Each 125V de board provides redundant protection for a fault to prevent a loss of the board due to a fault in one circuit. In any situation involving loss of a part, or a .whole 125V de bus, g-

.g actions should be taken to determine the cause and extent of the loss and restore as much of the bus to normal as soon as possible. .

In' general, 125V de battery board I supplies control power for Unit 1 Train A equipment and solenoid valves; however, it does supply control power to some equipment and control buses for Unit No. 2. 125V de bus I can be energized by

- 125V de battery I, from 125V de vital battery charger I, from 125V de vital battery charger 1-S, or from the fifth vital battery.-

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