ML19208C833

LER 79-110/01T-0:on 790910,noted Ambient Temp Gauges Could Affect Capability of Diesel Generator Fan Cooling Sys So That Insufficient Cooling Would Be Provided.Caused by Improper Pitch Setting on Fan Blade

ML19208C833
Person / Time
Site:	North Anna
Issue date:	09/24/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19208C826	List: ML19208C825 ML19208C833 ML19208C836
References
LER-79-110-01T, LER-79-110-1T, NUDOCS 7909270552
Download: ML19208C833 (2)

Text

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EVENT OATE 74 75 REPOR T O ATE 7 60 61 DOCKE T NUVdER EVENT DESCRIPTION AND PRGBABLE CONSEQUENCES h o 2 l On September 10, 1979, during Mode 1 operation, Vepco discovered that ambient temperaq o 3 l ture ranges could exist where the design capability of the diesel generator fan cool-j o l4 l l ing system would be exceeded and cooling may be insuf ficient. Because temperature l g3J l exi;remes are not likely and the diesel generators have operated satisfactorily throug!}-

O 6 l out the summer, the health and safety of the general public are not affected by this o 7 l event. Reportable pursuant to T.S. 6.9.1.8.f. and i. l 8

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42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i o l 'Ihe cause of this problem is that the fan blades may not have the proper pitch setting gijil l to provide the necessary cooling for the wide range of temperatures that can occur l

, , l during the year. Discussions with t'e n vs.ndor are in progress to determine resolutiong

[,;3l l to the cooling problem.

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? 8 9 10 64 69 80 5 NAME OF PREPARER W. R. Ca rtwricht 'H ON E : (703)894-5151

Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER 79-110/01T-0 Description of Event On September 10, 1979, during normal operation at 86% power, Vepco discovered that there are possible periods during the year when ambient temperature ranges are such that the diesel generator fan cooling system design is inade-quate to provide sufficient cooling. Additionally, it was discovered that procedures did not address the existing vendor requirement concerning seasonal temperature variations and the need to vary blade pitch accordingly.

Probable Consequences of Occurrence At present, tempercture extremes are not likely to occur and also the emergency diesel generators have operated satisfactorily during the summer. As a result, the public health and safety have not been affected by this event. Unit 2 has identical diesel generators which possess the same cooling problem.

Cause The cause of this problem is that the fan blade pitch settings may be inadequate to provide the necessary diesel generator cooling for the wide range of tempera-tures that ccn occur during the year.

Immediate Corrective Action Discussions with the vendor are being conducted to determine the actions necessary to correct the cooling problem. Changing the fan blade pitch settings and adding glycol to the radiator is presently being investigated. Also, fan coupling redesign is under review.

Scheduled Corrective Action To be determined by the discussions with the vendor.

Actions Taken To Prevent Recurrence No further actions required.

LERFOR:B2 1U43 049