ST-HL-AE-5738, Special Rept:On 970821,declared Standby DG 21 Inoperable to Allow Repairs.Fuel Rack Sys Set of Rotating Shafts & Lever Arms Connecting Engine Governor to Individual Cylinder Fuel Injection Pumps.Binding Ball Joint Replaced

Special Rept:On 970821,declared Standby DG 21 Inoperable to Allow Repairs.Fuel Rack Sys Set of Rotating Shafts & Lever Arms Connecting Engine Governor to Individual Cylinder Fuel Injection Pumps.Binding Ball Joint Replaced

ML20210T806
Person / Time
Site:	South Texas
Issue date:	09/09/1997
From:	Parkey G HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-5738, NUDOCS 9709160115
Download: ML20210T806 (4)

Text

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1 The Light cllouison o m 1.lghting p a n &y Power South Tenas Project Electric Generailug Station P. O. Bos 289 Wadsworth, Tesaa 71483 September 9,1997 STllL AE 5738 File No.: G03.03 10CFR50 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 0001 South Texas Project Unit 2 Docket No. STN 50 499 Special Report Regarding Standbv Diesel G-nerator #21 Valid Failure on August 19.1997 Pursuant to South Texas Project Technical Specifications 4.8.1.1.3 and 6.9.2, the South Texas Project submits the attached Special Report regarding a valid failure of Standby Diesel Generator 21 on August 19,1997.

If you should have any questions on this matter, please contact either Mr. S. M.

Ilead at (512) 972-7136 or me at (512) 972 7988.

G. L. Parkey Plant Manager, Unit 1 JMP/

Attachment:

Special Report Regarding a Valid Failure of )

Standby Diesel Generator 21 on August 19,1997

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liouston Lighting & Power Company ST llL-AE 5738 South Texas Project Dectric Generating Station File No.: G03.03

, , Page 2 D

Ellis iV. Merschoff Rufus S. Scott Regional Administrator, Region IV Associate General Counsel

. U. S. Nuclear Regulatory Commission Houston Lighting & Power Company

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61! Ryan Plaza Drive, Suite 400 P. C Box 61067 Arlington, TX 760114 064 llous on, TX 77208 Tlwrm, W. Alexion Institute of Nuclear Power Project Manager, Mail Code 13113 Operations - Records Center  ;

( U. S. Nuclear Regulatory Commission 700 Galleria Parkway  ?

) Washington, DC 20555-0001 Atlanta, GA 30339 5957 l e

David P. Loveless Dr. Bertram Wolfe Sr. Resident Inspector 15453 Via Vaquero

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c/o U. S. Nuclear Regulatory Comm. Monte Sereno, CA 95030 k- P. O. Cox 910 L Bay City, TX ' 77464-0910 Richard A. Ratliff Bureau of Radiation Control J. R. Newman, Esquire Texas Depaitment of licalth Morgan, Lewis & Bockius 1100 West 49th Street 1800 M Stwt,N.W. Austin, TX 78756-3189 Washington, DC 20036-5869 g

J. R. Egan, Esquire i M. T. Hardt/W. C. Gunst Egan & Associates, P.C.

City Public Service 2300 N Street,'N.W.

P. O. Box 1771 Washington, D.C. 20037 San Antonio, TX 78296 J. C. Lanier/M. L. Lee U. S. Nuclear Regulatory Commission City of Austin Attention: Document Control Desk Electric Utility Department Washington, D.C. 20555 0001 721 Barton Springs Road Austin, TX 78704 Central Power and Light Company

_ ATTN: G. E. Vaughn/C. A. Johncon L P. O. Box 289, Mail Code: N5012 Wadsworth, TX 77483 1

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Attachment ST IIL-AE 5738 Page1 of2 Special Report Regarding Standby Diesel Generator #21 Valid Failure on August 19.1997 y DESCRIPTION OF EVENT 3

3r On August 19,1997, Unit 2 was in Mode 1. Following a successful monthly loaded run surveillance on Standby Diesel Generator #21, it was noted that the engine took longer to shutdown than nonnal. Investigation revealed that the fuel racks had not traveled fully to zero fuel. Further investigation found a binding balljoint in the fuel rack system. SDG 21 was declared inoperable to allow repairs.

3 The fuel rack system is a set of rotating shafts and lever arms connecting the engine governor actuator to the individual cylinder fuel injection pumps. The connecting links from one lever arm to the next are fitted with ball joints on each end to allow joint motion and rotation while maintaining link length constant. The binding ball joint did not allow normaljoint rotation and prevented full rack travel to the zero fuel position.

k The binding balljoint was replaced and SDG 21 was stated to verify operability. SDG 21 functioned satisfactorily following the repair, and was declared operable. SDG 21 was inoperable for approximately eighteen hours.

The failed part was inspected. The hol!ow ball in the ball joint was found cracked in two places. These cracks were the apparent cause of the binding.

Physical symptoms for this event were a physically bound rack linknge (could not be hand rotated) and the fuel injection pumps not at zero fuel. The remaining Standby Diesel Generators (22 and 23 in Unit 2,11,12, and 13 in Unit 1) were walked down and verified to have correct rack position and no binding linkages. The remaining fuel rack linkages on SDG 21 were also checked and were satisfactory.

The estimated rack lhkage forces present at the time of discovery, the estimated force used to move the fuei racks towards zero fuel egainst the binding, and the governor actuator force available during engine opeution were reviewed. It is believed that the governor actuator could not have overcome th. fual reck binding edequately to ensure satisfactory engine operation. Due to this consideraton, this SDG 21 event was classified as a Valid Failure.

CAUSE OF EVENT The apparent cause of this event is a cracked ball in a fuel rack ball joint. The failed component is undergoing failure analysis. The root cause for the failure has not yet been i dewrrnined.

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ANALYSIS OF EVENT This event was classified as a Valid Failure, since it is believed that the capability for  ;

SDG 21 to perform its design function had been compromised. Including this Valid l

Failure, for SDG 21 there has been one Valid Failure in the last 20 Valid Tests, one Valid Failure in the last 50 Valid Tests, and one Valid Failure in the last 100 Valid Tests. Since no trigger values have been exceeded, the surveillance testing frequency remains at monthly.

CORRECTIVE ACTIONS

1) The binding balljoint was r, placed and SDG 21 was tested satisfactorily.

2) The other fuel rack linkages in SDG 21 were verified to not be binding.

3)- The fuel rack linkages on the remaining five SDGs were checked a not be binding.

4) Based on the results of the root cause detennination, the South Texas Project will develop further corrective actions, as necessary. Should any significant-( information be identified as a result of the root cause determination, a supplement

[ to this report will be submitted.

1 ADDITIONAL INFORMATION The diesel generator is a Cooper-Bessemer model KSV-20 engine rated at 5500 KW, The binding balljoint is a Cooper-Bessemer part number SF-96-l#4, " Rod End".

Discussions with the vendor found no knowledge of similar failures with this model diesel generator.

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