05000366/LER-1979-135, Updated LER 79-135/03X-1:on 791219,power Supply a for RCIC Steam Leak Detection Sys Failed.Caused by Excess Current on 125-volt Dc Input to Power Supplies Blowing Fuses 7A & 7B.Fuses Replaced

Updated LER 79-135/03X-1:on 791219,power Supply a for RCIC Steam Leak Detection Sys Failed.Caused by Excess Current on 125-volt Dc Input to Power Supplies Blowing Fuses 7A & 7B.Fuses Replaced

ML20064M271
Person / Time
Site:	Hatch
Issue date:	02/08/1983
From:	Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20064M241	List: 05000366/LER-1979-135, Forwards Updated LER 79-135/03X-1
References
LER-79-135-03X, LER-79-135-3X, NUDOCS 8302150517
Download: ML20064M271 (2)

LER-2079-135, Updated LER 79-135/03X-1:on 791219,power Supply a for RCIC Steam Leak Detection Sys Failed.Caused by Excess Current on 125-volt Dc Input to Power Supplies Blowing Fuses 7A & 7B.Fuses Replaced

Event date:
Report date:
3662079135R00 - NRC Website

text

NRC FORM 366 U. S. NUCLE AR REGULATORY COMMISSION j DATE REPORT - N M S I LICENSEE EVENT REPORT REPORT DATE 1/8/80 coaTRol BLOCx: l l l l l l lh (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 7 o 1 8 9 l Gl Al El Il Hl 2 l@l LICENSEE CODE 14 015 l 0 l -l 0 l 0LICENSE l 0 l NUMBER 0 l 0 l - l 0 l 0 l@l 25 4

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7 8 60 61 68 74 75 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h I O'l 2 l l While operating at steady-state power on December 19, 1979, the "A" l g l power supply for the RCIC Steam Leak Detection System failed. The l l 0 l4 l l redundant system channel was operable. On December 20, 1979, at steady 4 l0lsl l state power, the "B" power supply for the RCIC steam leak detection l

[ O s Isystem failed. The "A" system had been returned to service and was l l 0 l 2 l l operable. The health and safety of the public were not affected by thist lO18l l non-repetitive event. l 7 8 9 80 C DE CODE SUBCO E COMPONENT CODE SUB OD'E SU E

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44 47 i CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h Iil0; l The cause of both events was attributed to' excess current on the 125VDC l j i i l input to the power supplies. The excess current caused fuses 7A and 7B l

, , lto blow, disabling the power supplies. The fuses were replaced. This l

, ., l event recurred while investigating the cause. Miscellaneous components l 3 4 l that had failed were replaced. l

'7 8 9 80 STA S  % POWE R OTHE R ST ATUS SO RY DISCOVERY DESCRIPTION I

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LER No.: 50-366/1979-135, Revision 1 Licensee: Georgia Power Company

. Facility: Edwin I. Hatch Docket #: 50-366 Narrative Report for LER 50-366/1979-135, Revision 1 Update Report - Previous Report Date 1/8/80 While operating at steady-state power on December 19, 1979, the "A" power supply for the RCIC steam leak detection system failed when a fuse on the 125VDC input blew. The failure caused four temperature switches to isolate. The redundant logic was operable. The fuse was replaced and the subsystem was returned to service. While operating at steady-state power on December 20, 1979, the "B" power supply for RCIC steam leak detection system failed in like manner as the "A" power supply above. The "A" logic was operable at the time. The fuse was replaced and the system returned to operable status. The health and safety of the public were not affected by this non-repetitive event.

This type instrument is utilized in other systems on both units, but no generic problems have been discovered at this time.

The cause of both events was attributed to excess current on the 125VDC input to the power supplies. The excess current caused fuses 7A and 7B to blow, disabling the power supplies. The fuses were replaced, and after further investigation it was discovered the contacts needed cleaning, the blower fan had to be replaced, and the cover plate over the capacitor circuit needed insulation to prevent short circuiting the capacitors whenever the plate was touched. These problems have been corrected.

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