ML20085M895

AO BFAO-7336W:on 731114,during Hot Standby Condition,Hpci Inverter Power Supply Fuse Failed.Caused by High Voltage Spike During Surveillance Check of Newly Installed 1/4-amp Switches.Spike Suppressor Installed

ML20085M895
Person / Time
Site:	Browns Ferry
Issue date:	11/21/1973
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
AO-BFAO-7336W, NUDOCS 8311090445
Download: ML20085M895 (3)

Text

r ,

a.-.m..-..- . . pm .. -

i" o "; o V (' I

! l

~

' TENNESSEE VALLEY AUTHORITY E'7 CHA ANDOGA, TENNESSEE :J ' ' ;p

,- i, l

37401 Li  ; U#

.Jk.. U November 21, 1973 syrgygWte%

PARTNERSHIP Y' 'r gE y, w>;m .Q Mr. John F. O' Lear /, Director

,DlX A

F Directorate of Licensing Office of Regulation U.S. Atomic Energy Comission Washington, DC 20545

Dear Mr. O' Leary:

TE:CTBSSEE VALLEY AUTHORITY - ERC'JI;S FERRY I!UCL3AR PLZ'f UNIT 1 -

DOCKBT HO. 50-259 - FACILITY OPERATI:iG LICHICE DPR IE 0ICGL OCCURRKICE REPCRT IFAO-7336v The enclosed report is to provide detailo concerning HPCI inverter power rupply fuce failure on Ercuns Fer.g nuclear Plant unit 1 on November 14, 1973, and ic submitted in accordance with I,ppendi:: A-to Reculatory Guide 1.16, Revision 1, October 1973 Verj truly yours, TE:EESSEE VAIL 2Y AUTHORITY

.N . 7 "I rector of Po'.scr Production Enclocurea CC(Enclocure):

Mr. !!cmsn C. Moseley, Director

. Region II Regulatory Cperations Office, USAEC 230 Peachtree Street, L"J.

Atlanta, Georgia 30303

.D./

hl! fh ,

$' g &,

Wh

@q\ [.V.:,

~

ngG. ;}

{okYo O rI e

. i v

'eM ,

• k 4 kW -*W'"EG"4 m'T87 8 Ge*** *'N' e M p , ,i.m-v'aY_* 4 .m.

~

. J. ,

O O l ,

ABNOK4AL OCCURRENCE REPORP Report No.--BFAO-7336W Report Date--November 21, 1973 Occurrence Date--Hovember 14, 1973 Facility--Browns Ferry Nuclear Plant -

Identification of Occurrence

. HPCI inverter power supply fuse failure.

Conditions' Prior to Occurrence The reactor was in the hot-standby condition at approximately 300 psig.

Description of Occurrence - -

At 10:00 a.m., the H"CI inverter power supply fuse failed. The fuse was inanediately replaced making the system operable. The fuse blev again at 10:45 a.m.. The fuse was again replaced making the system operable.

Designation of Anparent Cause of Occurrence At the time of the occurrence, plant e=ployees were conducting Surveillance Instruction 4.2.B-26, to check newly installed 1/4-ampere switches (see BFAO-7332W). A high voltage spike was experienced when the contacts in this instrumentation were opened, thus deener6 1zing the relay which actuates on -

condensate header low pressure. This relay is a part of the HPCI logic and is on the same 250V d-c bus as the inverter circuit.

Analysis of Occurrence Durin6 the brief interval between fuse failure and replacement, all remaining safety systems were available. After the second failure, all work on Surveillance Instruction 4.2.B-26 was teminated until the problem was corrected.

Corrective Action A spike suppressor vas placed across the coil of the relay. .When tested several~

times, the suppressor greatly reduced the spike experienced when the ' relay was deenergized and fuse failure did not occur. .

l' .

e

___.________________h

1

."4p

~~

Failure Data ')

i A record of previous failures can be found in BFAO-739W, BFAO-7318W, and-BFAO-7329W. The nameplate data for the inverter power cupply is as follows:

Topaz, Model 500-GVD-250-60-115, Serial No. 70%

9 4

e I ,

4 e

e.

O P

S a

0 6

6 e

9 a

b 1 .

l .e -

l' .#.

• r e -; p '.. .

t .

.

• a I i@

9 b s e  % _:

_ _. '_