ML19329B900
| ML19329B900 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/19/1977 |
| From: | Batch S, Lingenfelter J TOLEDO EDISON CO. |
| To: | |
| Shared Package | |
| ML19329B835 | List: |
| References | |
| NUDOCS 8002060894 | |
| Download: ML19329B900 (3) | |
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@l Essential Inverter YV1 was accidentally tripped causing losis of j
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(NP-33-77-14)
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TOLEDO EDISCN COMPAUY DAVIS-BESSE UNIT ONE HUCLEAR PCiiER STATION p)
SUPPLEMEIITAL ILFORMATION FOR LER NP-33-77-14
'NJ DATE OF EVENT: June 22, 1977 FACILITY: Davis-Besse Unit 1
-3 IDEhTIFICATION OF OCCURRENCE:.
Ioss of Safety Features Actuation System Channel 1 due to loss of Y1 Conditions Drior to Occurrence:
The plant was in Mode 5, with power ET = 0, MWE = 0.
Description of Occurrence:
On June 22, 1977 at 06 W, an Instrument and Control Technician shorted to ground a slide link which supplied AC voltage to the Decay Heat Essential Flow Instru=entation Cabinet. This caused a loss of Essential Instru=en-tation Distribution Panel Y1, resulting in the tripping of Safety Features Actuation System (SFAS) Channel 1 and Reactor Protection System (RPS)
Channel 1.
The Essential Instrumentation Distribution Panel Y1 was
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supplied by its alternate source YAR, and RPS Channel 1 and SFAS Channel.1 were re-energized at 0720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />.
Designation of Aprarent Cause of Occurrence:
The shorting of the slide link supplying the Decay Heat Essential Flow Instrumentation Cabinet was due to a personnel error on the part of the Instrument and Control Technician. The loss of Essential Instrumentation Panel Y1, and subsequent trip of SFAS Cha e l 1 and RPS Channel 1, however, can be attributed to a desi n problem in the Inverter YV1.
6 Analysis of Occurrence:
Since three of four SFAS channels were still operable, and SFAS Channel 1 was tripped, the SFAS would operate if required. The health and safety of the public and station personnel were not endangered.
Corrective Action:
Panel Y1 was supplied by its alternate source, YAR, and SFAS and RFS Channels 1 were re-energized within an hour after tripping occurred. This re=oved the station from the Action Statement' of Technical Specification N
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The manufacturer has been previously notified as to the defective
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inverter desi n, and is working to modify it.
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,a TOLEDO EDISON COMPA!Tf i
DAVIS-EESSE tETIT ONE frJCLEAR POWER STATIC!!
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. SUPPLEME:frAL INFCRMATION FOR LER NP-33-77-14 Page 2 l
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. Failure Data:
Shorting of slide link has not previously occur;ed, but defective inverter design was partial cause in another event: NP-33-77-6 i
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