RBG-42241, Special Rept:On 950912,EDG Failed to Start During Test. Caused by Machining Errors Caused by Mfg Resulted in Binding Between Piston & Bore

Special Rept:On 950912,EDG Failed to Start During Test. Caused by Machining Errors Caused by Mfg Resulted in Binding Between Piston & Bore

ML20095E885
Person / Time
Site:	River Bend
Issue date:	12/12/1995
From:	James Fisicaro ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RBF1-95-0294, RBF1-95-294, RBG-42241, NUDOCS 9512180196
Download: ML20095E885 (2)

Text

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Ent:rgy Oper:tiins,Inc.

River Bend Station 5485 U S Highway 61

==~~ ENTERGY l r #Jiu-5 Te1504 336 6225 Fax 504 635 5006

• James J. Fisicaro Director Nuclear Safety December 12,1995 U.S. Nuclear Regulatory Commission Document Control Desk Mail Stop PI-37 Washington, D.C. 20555

Subject:

River Bend Station - Unit 1 -

Docket No. 50-458 Final Special Report - Failure of Division I Starting Air Block and Vent Valve File No.:- G9.5, G9.25.1.7 RBG-42241 RBF1-95-0294 Gentlemen:

On September 12,1995, River Bend Station (RBS) submitted an Interim Special Report concerning a monthly operability surveillance, performed on the Division 1 Emergency Diesel Generator (EDG) on August 16,1995. The EDG failed to start during the test. The Interim Special Repon provided tLe event details as well as the initial results of River Bend's evaluations and statistical data. This fimI report documents the conclusions of the root cause investigation and corrective actions.

l An independent offsite consultant performed a formal root cause evaluation to verify the preliminary conclusion and to establish the root causes of the failure. This investigation concluded that the root cause of the air block and vent valve failure is machining errors caused by the manufacturer that resulted in binding between the piston and bore. The investigation also concluded that this was an isolated failure; therefore, the corrective actions to replace the valve as l documented in the previous report, are adequate to prevent recurrence. However, additional measures are being taken to enhance the valve inspection processes prior to installation. These j actions will be tracked in accordance with the RBS corrective action program. j l

1SC01G l i t i l l "

9512190196 951212 } 0

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i PDR ADOCK 05000458 l 8 PDR  !

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Final Special Repon - Failure of Division I Starting Air Block and Vent Valve December 12,- 1995  ;

RBG-42241 i I

RBFlyS4294 Page 2 of 2 If there are any questions concerning this issue please contact D. N. Lorfing at (504) 381-4157.

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Sincerely,

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F/WJF/jr 1

cc: U.S. Nuclear Regulatoiy Comnussion j 611 Ryan Plaza Drive, Suite 400 l Arlington, TX 76011 NRC Sr. Resident Inspector P.O. Box 1051 St. Francisville, LA 70775 i

INPO Records Center ,

700 Galleria Parkway l Atlanta, GA 30339-3064 l l l Mr. C.R. Oberg q

Public Utility Commission of Texas i 7800 Shoal Creek Blvd., Suite 400 Nonh Austin, TX 78757 Louisiana Department of Environmental Quality 3 Radiation Protection Division l P.O. Box 82135  ;

l Baton Rouge, LA 70884-2125 i ATTN: Administrator '