ML20205B669
| ML20205B669 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 03/17/1987 |
| From: | Hunsader S COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 1655W, NUDOCS 8703300023 | |
| Download: ML20205B669 (3) | |
Text
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One Fret Nabonel Plara, Chcago, IEnos j
~ * (g Address Reply to: Post Omco Box 767
- Chica00. iEnois 60600 0767 l
March 17, 1987 Mr. A. Bert Davis Acting Regional Administrator U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137
SUBJECT:
Braidwood Station Unit 2 10 CFR 50.55(e) 30-day Report Diesel Engine-Generator Rocker Arm Failure NRC Docket No. 50-457
Dear Mr. Davis:
On February 17, 1987, the Commonwealth Edison Company notified your office of a potential deficiency reportable pursuant to 10 CFR 50.55(e) regarding the subject failure at our Braidwood Station. This letter provides information concerning this matter to fulfill the thirty day reporting requirement. For tracking purposes, this deficiency was assigned Number 457/87-01.
Please address any questions that you or your staff may have concerning this matter to this office.
Very truly yours,
,h
-A Steven C. Hunsader Nuclear Licensing Administrator SCH/RCB/mjv (4774z) cc: NRC Resident Inspector - Braidwood Director of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 0703300023 870317 PDR ADOCK 05000457 PDR S
gg 2 31987 3EA7
4
' Description of Deficiency The Braidwood 2A (2DG01KA) Diesel Generator experienced an inlet and' exhaust rocker arm failure in cylinder 5R on February 13, 1987, after running for approximately 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br />. Results of an investigation conducted by commonwealth Edison Company and Cooper-Bessemer Reciprocating Engineers attribute a probable initiating cause of failure as momentary seizure of a crosshead in the crosshead guide leading to shock loading of the rocker arms.
The momentary seizure could have been caused by paint chips or other small debris which was found in the camshaft trough during the investigation.
. Analysis of Safety Implications This type of failure would not have prevented the diesel engine-generator sets from providing emergency A.C. Power. Rocker arm breakage will not cause additional mechanical damage. The only effect on the engine will be loss of power from the affected cylinder. There is sufficient margin in these engines such that the loss of one cylinder will not prevent the engine from producing full power.
Corrective Action Taken The 2A Diesel Generator cylinder 5R was repaired by honing out the crosshead to crosshead guide clearance to 0.006 inches and replacement of damaged parts. Additionally, crosshead to crosshead guide clearances for 7 other cylinders which exhibited slight drag in a hot condition were honed out from 0.004 inches to 0.006 inches. The camshaft troughs were cleaned out and upper lube oil lines to the rocker arms were flushed out. The cylinder SR broken rocker arm was returned to Cooper-Bessemer for metallurgical j
testing. Cooper-Bessemer representatives were present during repair activities.
After reassembly, the 2A Diesel Generator underwent a planned 100-hour test run. After starting, test engineers verified the diesel generator was running acceptably. The diesel generator was then run at approximately one-third load for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />. After 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, the diesel generator was run at full load for approximately 4
94 hours0.00109 days <br />0.0261 hours <br />1.554233e-4 weeks <br />3.5767e-5 months <br />. Commonwealth Edison Company test engineers and Cooper-Bessemer representatives were present during the test run.
i During the test run, cooper-Bessemer representatives took engine vibration traces and peak pressure traces. The traces showed no
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abnormalities and met Cooper-Bessemer parameters. Upon completion of the test run, crosshead to crosshead guide movement in the hot condition was taken and no abnormalities were present. A post-run lube oil chemical analysis was performed and no abnormalities were present. The 2A Diesel Generator was declared ready for remaining
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preoperational testing.
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- Cooper-Be= emer h:3 not mada o final d3tcrcination of causa cf failure. Metallurgical test results of failed cylinder 5d rocker arm have not been received from Cooper-Bessemer. When this information is received, a final report will be submitted. This is expected by the end of April 1987.
1655W 1
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