ST-HL-AE-5620, Special Rept:On 970312,declared Standby Diesel Generator 13 Inoperable.Caused by Inoperative Reset Coil on K1 Relay. Reinstalled Original K1 Relay in Standby Diesel Generator 13 & Tested Satisfactorily & Sent Failed K1 Relay to Vendor

Special Rept:On 970312,declared Standby Diesel Generator 13 Inoperable.Caused by Inoperative Reset Coil on K1 Relay. Reinstalled Original K1 Relay in Standby Diesel Generator 13 & Tested Satisfactorily & Sent Failed K1 Relay to Vendor

ML20137T160
Person / Time
Site:	South Texas
Issue date:	04/09/1997
From:	Parkey G HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-5620, NUDOCS 9704160007
Download: ML20137T160 (4)

Text

.

The Light c o mp a ny ut h Texas Project Dectric Generating Station P. O. Box 289 Wadmonh, Texas 77483 Houston Lighting & Power April 9, 1997

' ST-HL-AE-5620 File No.: G02 10CFR50 U. 3. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Unit 1 Docket No. STN 50-498 Special Report Regarding a Valid Failure of Standby Diesel Generator 13 on March 12.1997 Pursuant to South Texas Project Technical Specifications 4.8.1 l.3 and 6.9.2, the South Texas Project submits the attached Special Report regarding a valid failure of Standby Diesel Generator 13 on March 12,1997.

l If you should have any questions on this matter, please contact either Mr. S. M. Head l at (512) 972-7136 or me at (512) 972-7800.

I l

G. L. Parkey /

Plant Manager, I Unit I /

9704160007 970409 PDR ADOCK 05000498 g 1ew =

S PDR ,

DNB/

Attachment:

Special Report Regarding a Valid Failure of gggggggggjpggggggg Standby Diesel Generator 13 on March 12,1997 '

sREP-976620.wp Project Manager on Behalf of the Participants in the south Texas Project sTI: 30241663 j

1 . ,

! . Houstontighting & Power Company ST-HL-AE-5620  ;

File No.: G02 South Tegas Project Electric Generating Station  ;

3 Page 2 j i

1

[

l Ellis W. Merschoff Rufus S. Scott  ;

Regional Administrator, Region IV Associate General Counsel '

U. S. Nuclear Regulatory Commission Houston Lighting & Power Company l 611 Ryan Plaza Drive, Suite 400 P. O. Box 61067 l Arlington, TX 76011-8064 Houston, TX 77208

) Thomas W. Alexion Institute of Nuclear Power l Project Manager, Mail Code 13H3 Operations - Records Center U. S. Nuclear Regulatory Commission 700 Galleria Parkway Washington, DC 20555-0001 Atlanta, GA 30339-5957  ;

1 i

! David P. Loveless Dr. Bertram Wolfe l Sr. Resident Inspector 15453 Via Vaquero Monte Sereno, CA 95030 I j c/o U. S. Nuclear Regulatory Comm.

P. O. Box 910 i Bay City, TX 77404-0910 Richard A. Ratliff Bureau of Radiation Control

J. R. Newman, Esquire Texas Depanment of Health j Morgan, Lewis & Bockius 1100 West 49th Street j 1800 M Street, N.W. Austin, TX 78756-3189

Washington, DC 20036-5869  ;

) J. R. Egan, Esquire ,

1 M. T. Hardt/W. C. Gunst Egan & Associates, P.C.  !

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

j P. O. Box 1771 Washington, D.C. 20037 i San Antonio, TX 78296  :

l J. C. Lanier/M. B. Lee U. S. Nuclear Regulatory Commission

,. City of Austin Attention: Document Control Desk j Electric Utility Depanment Washington, D.C. 20555-0001 721 Barton Springs Road j Austin, TX 78704 i

l Central Power and Light Company ATTN: G. E. Vaughn/C. A. Johnson P. O. Box 289, Mail Code: N5012 Wadsworth, TX 77483

. Attachment ST-IRE-5620 Page 1 of 2 Special Report Regarding a Valid Failure of Standby Diesel Generator 13 on March 12.1997 l

Description of Event:  ;

On March 12,1997, at 1029 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.915345e-4 months <br />, Unit I was in Mode 1. While performing an operability test, Standby Diesel Generator 13 failed to obtain normal voltage and frequency during an emergency mode start. The engine attained rated speed, but there was no indication of generator output voltage in the control room or locally. The engine was secured and declared inoperable.

Troubleshooting determined that the K1 relay failed to reset on start as designed. As part of an equipment upgrade, the K1 relay had been recently replaced with a new model relay. The new relay had been satisfactorily bench tested, in-circuit tested, and operationally tested. The failed relay was replaced with the original K1 relay.

Upon restoring power to the circuit, it was found that the redundant rated-speed / field flash slave-relay 14FFXI, which actuates the K1 relay as engine speed reaches a given setpoint, had also failed, apparently as a result of the K1 relay failure. The 14FFX1 relay was replaced.

Following replacement of the K1 and 14FFX1 relays, Standby Diesel Generator 13 was test started in both the test and emergency modes. A satisfactory loaded run surveillance test was performed, and Standby Diesel Generator 13 was declared operable on March 13,1997, at 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br />.

Cause of the Event:

The apparent cause of this event is an inoperative reset coil on the K1 relay, which prevented the relay from operating during engine start. This disabled the generator exciter field, preventing the generator from developing voltage. The failed K1 relay has been returned to the vendor to perform a failure analysis.

Event Analysis:

The diesel start was classified as a Valid Failure, because it could not perform its design function with this condition present. Including this Valid Failure, Standby Diesel Generator 13 has had one Valid Failure in the last 20 Valid Tests and three Valid Failures in the last 100 Valid Tests. The surveillance testing frequency remains monthly because no trigger values have been exceeded.

SREP-97\$620.wp sTI: 30241663

.. -.- -. -. .. - . - - . - - - . - - . - --.~..- .-.. _.-. - .-

. . Attachment  !

ST-HL-AE-5620 ,

j Page 2 of 2 4

i Corrective Actions: )

i

, The original K1 relay was reinstalled in Standby Diesel Generator 13 and tested satisfactorily. l

} With the replacement of the original (old version) K1 relt:.y in Standby Diesel Generator 13,

all of the Standby Diesel Generators at the South Texas Project have the original version K1

[ relay installed.

i The failed K1 relay has been sent to the relay vendor to perform a failure analysis. The

effort to replace the existing K1 relays with the upgraded model relays has been suspended until the root cause of this failure has been determined. Following root cause determination, i the South Texas Project will re-evaluate replacement of the existing K1 relays with the

upgraded versions.

Additional Information:

The failed K1 relay (upgrade relay) is a Square D Part Number LPID801 IGD contactor with an LA6DK3G latch.

The original K1 relay is a Telemechanique Part number A143E12-X3 contactor.

The 14FFX1 relay is an Agastat EGPDRC2015003.

l l

SREP-9N620.wp STI: 30241663