ML20010F847
| ML20010F847 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/01/1981 |
| From: | Papay L SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8109110452 | |
| Download: ML20010F847 (3) | |
Text
m 50.55(e) Report 7
Docket Nos. 50-?S1/362 Southem Caliromia Edison Company g5 RO. BON 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORMA 3t770 TELEPHh hh :0, m.m}.
i September 1, 1981 g
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.y Mr. R. H. Engelken, Director
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2 U. S. Nuclear Regulatory Corrmission 4 (.N ~
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Region V e
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Dear Mr. Engelken:
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's Subj ect:
Docket Nos. 50-361 and 50-362 San Onofre Nuclear Generating Station, Units 2 and 3 In a letter to your office cated August 4, 1981 we identified a condition which we considered potentially report-able in accordance with 10CFR50.55(e).
The condition involves failure of a camshaft support bearing bracket on a diesel gen-erator engine.
Enclosed are twenty-five (25) copies of a final report entitled, " Final Report on Diesel Generator Engine Camshaft Bracket Failure - San Onofre Nuclear Generating Station, Units 2 and 3."
If you have any questions regarding this report we would be pleased to discuss them with you at your convenience.
Very truly yours, J
l T677 Enclosures cc:
Victor Stello (NRC, Director I&E) jg R. J. Pate (NRC, San Onofre Units 2 and 3) 81091104b2 810901 PDR ADOCK 05000361 PDR S
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FINAL REPORT ON DIESEL GENERATOR CAMSHAFT BRACKET FAILURE Page 2 San Onofre Nuclear Generating Station, Units 2&3 This particular failure has been reported to have occurred on only two other EMD 20 cylinder engines, both in stationary, commercial service.
l
, Analysis of Safety Implications The Diesel Generator is a safety related component which is required to function during emergency conditions.
Had the failed bracket gc.,e undetected, further damage could have occurred, which migh. have impaired the ability of the Diesel Generator to pro ide standby power when required in an emergency condition.
Corrective Action The engine was partially dismantled to thoroughly inspect all affected engine components.
All damaged or suspected parts were replaced and the reassembled engine successfully tested to insure its operability.
The failed or damaged parts were returned to the supplier for analysis.
This failure was determined to te a relatively isolated instance, having been reported on two previous occasions in commercial ser-vice.' Compared with the large numbers of similar machines in service for very long periods, the frequency of this type of failure is extremely low.
Therefore, its occurrence is judged to be a non-generic, non-repeticive problem which can allow the end ne to be repaired and returned to service.
i W
FINAL REPORT ON DIESEL GENERATOR CAMSHAFT BRACKET FAILURE San Onofre Nuclear Generating Station, Units 2 and 3 INTRODUCTION This report is submitted pursuant to 10CFR50.55(e)(3)
It describes a condition discovered during preoperational testing of the Emergency Diesel Generators supplied by General Motors Corporation, Electromotive Division (EMD), La Grange,1311nois, through Stewart & Stevenson Services, Incorporated, of Haf tston, Texas.
This report includes a description of the condition, an analysis of tha safety implications, and a summary of corrective actions taken.
By letter dated August 4, 1981, Southern Califor-nin Edison confirmed notification to the NRC of this potentially reportable condition.
BACKGROUND During preoperational testing of one of the redundant diesel clectric generating sets for Unit 2, an cbnormal engine noise was detected and the unit was shutdown.
Upon a subsequent detailed inspection it was found that several components had failed or had been damaged in the 20 cylinder engine of the tandem unit.
The engine has twin overhead camshafts which are driven off the crankshaft through a set of gears.
The inspection revealed the right camshaft had suffered a failure of the camshaft stubshaft bracket, several bearing cap bolts, and a rocker arm oil feed line.
DISCUSSION The following discussion is responsive to 10CFR50.55(e)(3).
Description of the Deficiency The camshaft stubshaft bracket houses the camshaft thrust bearing
, and the first shaft line bearing.
The bracket was broken through at the attachment leg to the engine frame.
Two of four bearing cap bolts were also found broken where they attached to this bracket along with the two bearing cap bolts of the next line bearing.
No other damage to the bearings, gears, or camshaft was detected.
This failure allowed the camshaft to move axially beyond its normal move-ment.
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