ML19308A315

LER 79-026/03L-0 on 790215:Sys 7 Computer Tripped.Caused by Computer Core Cooling Fan Seizing & Overheating.Fan Replaced

ML19308A315
Person / Time
Site:	Davis Besse
Issue date:	03/15/1979
From:	Borysiak M TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19308A311	List: ML19308A309 ML19308A315
References
LER-79-026-03L, LER-79-26-3L, NUDOCS 7903200357
Download: ML19308A315 (2)

Text

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U. S. NUCLEAR REGULATORY COMMIS I RC FORM 366 (7 77)

LICENSEE EVENT REPORT (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATIONI

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60 61 DOCKE T NUvega fi3 t,3 EVENT DATE 14 75 REPORT DATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h This rendered [

m y] l On 2/15/79 at approximately 1130 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.29965e-4 months <br />, the System 7 Computer tripped.

the Fire Detection System rcnote monitoring system inoperable, and placed the unit in l g 3 the Action Statement of Technical Specification 3.3.3.8. As required by the Action l g , g Statement, a fire watch patrol was established to check all fire detection cabinets l 10151 There was no danger to the health and l o 16 l l hourly and guards were posted on vital doors.

l o l 7 l l safety of the public or to unit personnel. ( NP-33-79-30 )

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, o l The occurrence was due to a component ftilure of the computer's core cooling fan On 2/15/79. at. I i i l seizing and cubsequent overheating of the System 7 Computer core.

,,,,, g approximately 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, ter.porary cooling was established. This placed the system from the Action Statement of Technical Specifi-l lback in operation and removed the unit

cation 3.3.3.8. On 2/20/79, the fan was replaced.

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• o TOLFD0 EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION U'1IT ONE SUPPLEMENTAL INFOR'4ATION FOR LER NP-33-79-30

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DATE OF EVENT _: February 15, 1979 FACILITY: Davis-Besse Unit 1 Failure of the System 7 Security / Fire / Radiation IDENTIFICATION OF OCCURRENCE:

Computer The unit was in Mode 1, with Power (MWT) = 2397, Conditions Prior m Occurrence:

and Load (Gross MWE) - 805.

Description of Occurrence: On February 15, 1979 at approximately 1130 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.29965e-4 months <br />, the System 7 Computer tripped on a thermal overload. This rendered in the Fire Detection the Action State-System remote monitoring system inoperable, Theand placed Action the unit of Technical Specifi-Statement ment o f Technical Specification 3.3.3.8. The cation 3.3.3.8 requires an hourly fire watch be established within one hour.

Shift Foreman declared the System 7 Computer inoperable, notified station security to furnish guards, and established a fire watch to check all fire detection cabinets hourly.

The occurrence was due to a component Designation of Apparent Cause of Occurrence: overheating of failure of the computer's core cooling fan seizing and subsequent .,

the System 7 Computer core.

Anclysis of Occurrence: There was no danger to the health and safety of the public or to unit personnel. A fire watch was established and guards posted on vital doors.

Corrective Action: On February 15, 1979, at approximately 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the core was pulled from the cabinet and temporary cooling was establisned. This placed the system back in operation and removed the unit f;om the Action Statement of Technical Specifi-cation 3.3.3.8. On February 16, 1979, an IBM Service Representative was called and on February 20, 1979, the IBM Service Representative replaced the f an.

Failure Data: There have been two previously reported failures of the System 7 Computer, but the cause was not determined to be due to a fan failure (see Licensee Event Report NP-33-79-11).

LER #79-026