ML20237H501

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Rev 4 to Abnormal Operating Instruction AOI-25.7, Loss of 120-Volt AC Vital Instrument Power Board 2-III
ML20237H501
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 05/22/1987
From: Eaves H, Epperson J
TENNESSEE VALLEY AUTHORITY
To:
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ML20237H133 List: ... further results
References
AOI-25.7, NUDOCS 8708170241
Download: ML20237H501 (6)
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l TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT ABNORMAL OPERATING INSTRUCTION A0I-25.7 LOSS OF 120V AC VITAL INSTRUMENT POWER BOARD 2-III Unit 2 ,

Revision 4 PREPARED BY: Herb Eaves RESPONSIBLE SECTION: Operations REVISED BY: Jeff Epperson j

SUBMITTED BY: .rd. M b R onsibleSection$ppervisor PORC REVIEW DATE: MAY 2 21987 APPROVED BY: W

, Plant Manager i _

) DATE APPROVED: IMY)2 W

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

Revised to constitute a biennial review in accordance with AI-4. Appendix H. Streamline operator actions - delete erroneous appendices "A" and "B".

The last page of this instruction is number: 4

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SEQUOYAll NUCLEAR PLANT PLANT INSTRUCTION REVISION LOG ABNORMAL OPERATING INSTRUCTION A01-25.7 REVISION Date Pages REASON FOR REVISION (INCLUDE COMMIT-LEVEL Approved Affected MENTS AND ALL ICF FORM NUMBERS) 0 08/04/81 All 1 09/12/83 All 2 07/31/84 1,8 3 10/04/84 2~

Revised to constitute a biennial review in accordance with AI-4, Appendix H.

Title Chg Streamline operator actions - delete j 4

get'2 1987 All erroneous appendices "A" and "B".

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AOI-25.7 Page 1-Revision 4 I. SYMPTOMS A. Alarms

1. 120V AC VITAL INVERTER 2-III ABNORMAL.
2. 120V AC VITAL PWR BD 2-III UV OR BREAKER TRIP.

r-B. Indications

1. Power Range channel N-43 failure.
2. Auto and manual rod block and rod stop due to high flux rod.stop and C-5 interlock.
3. Loss of feedwater portion of signal to feedwater control ,

system resulting in failure to control steam generator

i. level if channel 3 is selected. '
4. Loss of steam generator level control due to loss l

of input signal to program on steam generators 2 and 3.

5. Possible reactor trip due to steam generator level changes.
6. Loss of auto makeup to VCT.
7. Malfunction of trip status lights and safeguards systems annunciators.

i C. System Partial Failures L

1. Reduction of feedwater flow due to demand signal from steam generator 3 falling low.

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2. Loss of power to solid state protection system input relays (Train A and B) and output relays (Train A) for channel III.
3. If pressurizer level is selected to channel LT-68-320 for control, pressurizer low level auto action will occur.
4. If Pressurizer pressure is selected to channel PT-68-323 the sprays will be closed and the backup heaters energized-

_ until locked out by the icw level signal if LT-68-320 was selected for level control.

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SQN AOI-25.7 Page 2 7 Revision 4 I. SYMPTOMS C. System Partial Failures (Continued)

5. Possible swap over of charging system from VCT to RHST.
6. Letdown divert valve LCV-62-Il8 diverts.to holdup tank and TIS-62-79 bypasses letdown demineralizers.
7. Loss of automatic control in auxiliary feedwater system of LCV-3-164 and LCV-3-156 (level control for S/G.1 and 2) for motor driven auxiliary feedwater pump 2A-A.
8. Loss of automatic control in auxiliary feedwater system of LCV-3-172 and LCV3-175 (level control for S/G 3 and 4) for turbine driven auxiliary feedwater pump 2A-S.

i NOTE: The above failures are of greatest immediate i consequences, for a complete list of loads on Vital Board 2-III refer to Appendix A.

l- II. AUTOMATIC ACTIONS l'~- A. Possible reactor trip due to low-low S/G level.

III. IMMEDIATE OPERATOR ACTIONS A. None IV. SUBSEQUENT OPER TOR ACTIONS A. If reactor trip cccurs then refer to eme'rgency instructions.

B. If reactor does not trip, then, at the NIS panel, defeat the PR rod stop.

C. Assume and maintain manual rod control.

NOTE: Do not use bank select; use of bank select will cause j the bank overlap program to be lost.

I D. Dispatch operator to restore power to failed board (transfer to auxiliary power supply).

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E. Assume manual control of steam generator water level on the affected steam generator.

F. Verify pressurizer level and pressure are not selected to LT-68-320 and PT-68 323 respectfully.

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, i SQN A0I-25.7 Page 3 Revision 4 I IV. SUBSEQUENT OPERATOR ACTIONS (Continued)

G. Assume manual control of VCT level.

NOTE:

If RWST suction valves are opened automatically, verify VCT level prior to returning to VCT suction valves.

H.

If power is restored to the failed boards, return systems to normal operating mode.

NOTE: l Due to feedback signals and time delays in circuitry, controllers may not control immediately. 4

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Evaluate the need to shutdown per TS 3.8.2.1 if power cannot be restored to the affected board. If necessary, commence ~ ,

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. orderly shutdown to hot standby condition per G0I-5'and GOI-3. 1 Initiate REP per IP-1 (Engineered Safety Features) as required.

Refer to TS 3.8.2.2.

,{ NOTE:

I I Operation may continue at the discretion of the Manager, t Operations Group, with respect to Tech Spec Section 3.

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- J. Dispatch operator to Cardox units to verify master valves i

are closed.

V. REFERENCES A. TS 3.8.2.1, 3.8.2 2 i1 E. S0I-55 Series

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, C. 45N706-3

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SQN AOI-25.7 Page 4 Revision 4 i

APPENDIX A i Page 1 of I Load List: 120V AC VITAL INST. POWER BD. 2-III SSPS'(A) CH III input and train A output relays (2-R-48)

SSPS (B) CH III input relays (2-R-49)

.NIS. inst, power CH III NIS control power CH III Process protection set III (2-R-9)

UNI accumulator CH III isol. valve FCV-87-23 ERCH and entmt. rad, monitor 2-RE-90-106 Cntmt annulus DP 2-PdIC-65-80 Aux. relay rack SSPS aux, relays (2-R-73)

RB isol. valve FCV-32-81A,81B Rad rate meters and 2-RI-90-106 l RCP 3 UV and UF relays 125V de vital battery bd. III instruments Letdown flow temp switch TIS-62-79 EGTS room cooler B-B-Post accident sampling solenoid valves PCO-65-81 and 86 aux relay (2-R-73)

BOP process instr. control rack (2-R-128)

AB instr. bus A Containment purge air exhaust rad monitor 2-RE-90-130 NSSS aux. relay rack, A bus (2-R-54)

Aux. relay rack sep. and aux. relays (2-R-73) -

Aux, control panel, A relay bus Aux, control panel, A. instr. bus Aux relay rack sep. and aux. relays (2-R-74)

BAT B htr. A-A controller TIT-62-239 Process control group 3 (2-R-20) '

Instr. bus 3 and transformer power FIC-3-48,70 Reactor vessel level instrumentation system

. VHF base station, PSS radio repeater A train plugmold (2-M-9)

UHI instr. bus 3 i

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