ML20237H400

Rev 6 to Abnormal Operating Instruction AOI-21.6, Loss of 125-Volt DC Vital Battery Board II

ML20237H400
Person / Time
Site:	Sequoyah
Issue date:	04/24/1987
From:	Brewer C, Epperson J TENNESSEE VALLEY AUTHORITY
To:
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References
AOI-21.6, NUDOCS 8708170188
Download: ML20237H400 (6)

Text

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TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT ABNORMAL OPERATING INSTRUCTION AOI-21.6 I

LOSS OF 125V DC VITAL BATTERY BOARD II' Unit 2 f

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Revision 6

L PREPARED BY:

C. O. Breker" RESPONSIBLE SECTION:

Operations REVISED BY:

Jeff Epperson SUBMITTED BY:

.ll sponsible Section Supervisor i

PORC' REVIEW ATE:

PR Y4 I987 APPROVED BY:

A L

Plant Manager

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DATE APPROVED:

APR 241987 i.

- Reason for revision (include all Instruction Change Form Nos.):

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

The last page of this instruction is number:

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SEQUOYAH', NUCLEAR PLANT PLANT INSTRUCTION REVISION LOG ABNORMAL OPERATING. INSTRUCTION AOI-21.6 REVISION Date Pages REASON FOR REVISION (INCLUDE COMMIT-LEVEL Approved Affected MENTS AND ALL ICF FORM NUMBER 3)'

3 7/12/83 All-4 8/13/84' 2

Cover Revised to change unit designation on 5

08/22/85 Page cover page from Unit 1 to Unit 2

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Revised to correct annunciations and APR 2 4 1987

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All actions section.

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AOI-21.6 l,.

Page 1 of 4 Revis' ion 6 l

I.

SYMPTOMS

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r A.

Possible alarms l.

125V DC VITAL CHARGER II FAILURE OR VITAL BATTERY II DISCHARGE.

2.

125V DC VITAL BATTFRY BOARD II ABNORMAL.

j 3.

6900V SHUTDOWN BOARD IB-B FAILURE OR BUS / NORMAL FEEDER r

UNDERVOLTAGE CR OVERVOLTAGE (1-M-1).

4.

6900V SHUTDOWN BOARD IB-B F/.ILURE OR BUS / NORMAL FEEDER UJDERVOLTAGE (0-M-26).

5.

480V SimTDOWN BOARD IB1-B FAILURE OR UNDERVOLTAGE (1-M-1 and 0-M-26).

6.

480V SlWTDOWN BOARD 1B2-A FAILURE OR UNDERVOLTAGE (1-M-1 and 0-M-26).

7.

6900V SHUTDOWN BOARD 2B-B FAILURE'OR UNDERVOLTAGE OR OVERVOLTAGE (2-M 8.

6900V SIfUTDOWN BOARD 2B-B FAILURE OR BUS / NORMAL FEEEDER UNDERVOLTAGE (0-M-26).

9.

480V SHUTDOWN BOARD 2B1-B FAILURE OR UNDERVOLTAGE (2-M-1 and 0-M-26).

10, 480V SHUTDOWN BOARD 2B2-B FAILURE OR UNDERVOLTAGE (2-M-1 and 0-M-26).

11.

SERVICE AIR COMPRESSOR SEQUENCER UNDERVOLTAGE OR C0 ALARM (1-M-15) 3.

Indications 1.

Voltmeter on 1-M-1 and 2-M-1 indicate failure of 125V de bus II.

2.

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

II. AUTOMATIC ACTIONS A.

All four diesel generators start but do not tie onto the shutdown board.

B.

All control and service air compressors will unload, resulting in decreasing control air pressure (VBB II supplies normal power to the compressors' sequencer).

III. IMMEDIATE OPERATOR ACTION None IV. SUBSEQUENT OPERA 10R ACTION A.

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

B.

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

SQN L

AOI-21.6 Page 2 of 4 Revision 6 IV.

SUBSEQUENT OPERATOR ACTION (continued)

C.

Have local inspection performed on 125V de vital battery board II to determine the cause of the failure. Try to restore voltage and initiate 3

maintenance if necessary.

D.

Transfer the following 125V de buses to alternate feed.

l C_AUTION: When transferring the 125V de bus to alternate or back g-to normal, have someone hold the B.O. reset button pushed

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in located in panel 4 of 6.9kV. logic panel 2B-B.

This will prevent the B.O. relays frota going to a B.O. c6ndition, which would sequence the CCP, AFWP, ERCW, PZR heaters, and fire pumps if an auto signal is present.

Xfer to Alt yR. urn to Normal 1.

6.9kV shutdown board 2B-B i

backup bus.

2.

480V shutdown board 2B1-B backup bus.

3.

480V shutdown board 2B2-B backup bus.

CAUTION: Verify Unit 1 operator following A0I-21.2 (Loss of Vital Battery Board II Unit 1) to ensure proper operation of air compressors)

E.

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

CAUTION: Coordinate this work with Unit 1 operator.

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1.

Place 4LT(L) switch (located on diesel generator logic panel 1B-B) in TEST position and leave it in TEST.

2.

Place all 43T(L) switches (located on diesel generator logic panels lA-A, 2B-B, and 2A-A) in the TEST position simultaneously and then return them to NORMAL.

3.

Reset the emergency start lockout relays for diesel generators 1A-A, 2B-B, 2A-A (located on each respective diesel generator relay panel in diesel generator building).

4.

Stop diesel generators lA-A, 2B-B, and 2A-A by placing.HS-82-14, HS-82-104, and HS-82-74 in STOP position.

5.

Diesel generator IB-B should be left running.

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SQN A0I-21.6 Page 3 of 4 Revis' ion 6 IV.

SUBSEQ'JENT OPERATOR ACTION (continued)

F.

Depending upon the cause of the failure or after repairs, voltage can be in 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.

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CAUTION:

If restoring voltage after a fault on the bus, use a battery I

charger for en,ergizing the bus if possible.

r NOTE:

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

G.

After voltage is restored to the bus:

1.

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

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2.

Return the diesel generators to their normal lineup by S01-82.1, 2, 3, 4.

V. REFERENCES i

A.

Technical Specification 3.8.2.3.

B.

FSAR 8.3.2 i

C.

Electrical Prints:

45N703-2 45N703-6 45N703-6 45N749-3 45N749-4 43N765-3 l

45N765-4 l'

45N767-5 45N630-2

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45N630-3 45N677-4 D.

Logic Diagrams E.

Control Diagrams L.

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F SQN r.

AOI-21.6 Page 4 of 4 Revision 6

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VI. DISCUSSION This instruction covers the loss of.125V de vital battery board II voltage.

This instruction assumes that Unit No. 2 is at power operation at the time of

..tc the event..The other three vital battery boards remain in normal operation l

throughout the duration of the event.

The unit can remain at power operation -

with no degradation of the unit safety related systems. Each 125V de cir-

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cuit is protected by a fuse,or breaker to clear a fault. The 125V de cir-

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cuit is also divided into branch buses which are supplied with fases'or breakers..,

to provide redundant. protection for a fault and prevent a loss of the board due to a fault in one circuit.

7 In any situation involving loss of a part of, or_a whole 125V de bus, actions should be taken to determine the cause and extent of the loss and restore as mush of the bus to normal as soon as possible.,

In general, 125V de battery board II supplies control power for Unit 1 Train B equipment and solenoid valves; however, it does supply sone by 125V de battery II, from 125V de vital battery charger II, from 125V de vital

• battery charger 1-S, or from the fifth vital battery.

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