05000318/LER-1981-004-03, /03L-0:on 810204, While Conducting Preventive Maint,Shutdown Cooling Flow Lost.Caused by Procedure Not Containing Sufficient Info.Flow Lost Due to de-energized Vital Ac Bus Causing Valve to Shut.Procedure Revised

/03L-0:on 810204, While Conducting Preventive Maint,Shutdown Cooling Flow Lost.Caused by Procedure Not Containing Sufficient Info.Flow Lost Due to de-energized Vital Ac Bus Causing Valve to Shut.Procedure Revised

ML20004D598
Person / Time
Site:	Calvert Cliffs
Issue date:	03/04/1981
From:	Rizzo P, Wenderlich R BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20004D590	List: 05000318/LER-1981-004, Forwards LER 81-004/03L-0 05000318/LER-1981-004-03, /03L-0:on 810204, While Conducting Preventive Maint,Shutdown Cooling Flow Lost.Caused by Procedure Not Containing Sufficient Info.Flow Lost Due to de-energized Vital Ac Bus Causing Valve to Shut.Procedure Revised
References
LER-81-004-03L-01, LER-81-4-3L-1, NUDOCS 8106090563
Download: ML20004D598 (2)

LER-1981-004, /03L-0:on 810204, While Conducting Preventive Maint,Shutdown Cooling Flow Lost.Caused by Procedure Not Containing Sufficient Info.Flow Lost Due to de-energized Vital Ac Bus Causing Valve to Shut.Procedure Revised

Event date:
Report date:
3181981004R03 - NRC Website

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U. S. NUCLEAR HEGULAiGHY CCWilSSION 17 77)

LICENSEE EVENT REPORT CONT Aol block: l l

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(PLEASE PRINT OR TYPE ALL REQutREO INFORMATION) 6 lo 11l l M l 01 C l C l N l 21@l 010 l - ! 010 l 01010 l-1010 l@l 411 11 11 l 1 ]@l l@

I 8 9 LICENSEE CQoE 14 15 LICENSE NUMBER 26

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4 60 61 ooCKET NuVSER 64 69 EVENT oATE 74 75

• E,CRT oATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h t o 121 i During Mode 6 operation at 2043 while conducting preventive maintenance, I

.i o s 3 i i lost shutdown cooling flow due to inadvertent deenergization of #21 1?.0V I

l o 14 : I Vital AC Bus (T.S. 3.9.8).

Deenergizing #21 120V Vital AC BLs caused 1

ic isi l 2-PIC-103 to deenergize, causing a shutdown cooling return header valve l

Io is i i to shut. At 2100, the bus was reencroized and flow restored.

No coera-I lo til I tions were in progress involving an increase in reactor decay heat load l

I o is I I or reductior in RCS boron concentration.

This is a non-recetitive event.

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liiall The oreventive maintenance orocedure in use by olant electricians did I

mI not contain sufficient information.

Procedures for Vital AC invertan I

tii2j 1 and Back-uo Bus comoonents are being revised to include soecifyino the 1

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81-04/3L DCCKET NO.

50-318 LICENSE NO.

DPR-69 EVENT DATE 02-04-81 REPORT DATE 03-04-81 ATTACHMENT EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (CONT'D)

During Mode 6 operation at 2043 while conducting preventive maintenance on No. 21 Vital A.C. Inverter, experienced a loss of shutdown cooling flow due to inadvertent deenergization of No. 21120V Vital A.C. bus, (T.S.

3.9.8). With No. 21120V Vital A.C. Bus on its backup power supply, a technician inadvertently opened the feeder breaker from the backup power supply, deenergizing No. 21120V Vital A.C. Bus. This caused 2-PIC-103 to deenergize, which caused a shutdown cooling return header valve,51-651 to shut. The operator then stopped No. 22 LPSI Pump. At 2100, No. 21120V Vital A.C. Bus was reenergized and shutdown cooling flow restored. During this event, no operations were in progress involving an increase in the reactor decay heat load or a reduction in the boron concentration of the Reactor Coolant System. This event had no impact on the public health or safety. This is a non-repetitive event.

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