ST-HL-AE-3600, Suppl Special Rept:On 900829,two Nonvalid Failures of Standby Diesel Generator 12 Occurred.Maint Completed & Diesel Satisfactorily Tested

Suppl Special Rept:On 900829,two Nonvalid Failures of Standby Diesel Generator 12 Occurred.Maint Completed & Diesel Satisfactorily Tested

ML20059P071
Person / Time
Site:	South Texas
Issue date:	10/15/1990
From:	Mcburnett M HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-3600, NUDOCS 9010250122
Download: ML20059P071 (4)

Text

n. . s A . :' g "i The Light companySouth Texas Project Dectric Generating Station P. O. Box 289 Wadsworth. Texas 77483 J Hom @tig & Pm October 15, 1990

(- ST HL-AE 3600 File No.: G02 10CFR50.36(c)(5) v

,, , -U 'S. Nuclear Regulatory Commission n ' Attention: Document Control Desk Washington, DC 20555 South Texas Project Electric Generating Station Unit 1 Docket No. STN 50-498 Supplemental Special Report 1

Regarding Two Nonvalid Failures of #12 .

Standbv Diesel Generator on Aunust 29. 1990 Pursuant to the South Texas Project Electric Generating Station Company Technical Specifications 4.8.1.1.3 and 6.9.2, Houston Lighting & Power.(HI4P)~

submits the attached Supplemental Special Report regarding two diesel generator nonvalid failures which occurred on August 29, 1990. A Special Report regarding the failure was provided to the NRC on September 28, 1990, reference-letter ST HL AE-3574.

If you should have any questions on this matter, please contact

.Mr. C.'A. Ayala at (512) 972-8628 or myself at (512) 972-8530, f l'I.

h A. /Vl0 fid/S YT McBurnett Manager,  !

Nuclear Licensing RAD /sgs-

Attachment:

Supplemental Special Report Regarding Two Nonvalid Failures of #12 Standby Diesel Generator on August 29, 1990 l

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ST-HL AE 3600

.Ilouston Lighting & Power Company

- South Texas Project Electric Generating Station File No.: G02 Page 2 cc:

Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel 611 Ryan Plaza Drive, Suite 1000 Houston Lighting & Power Company Arlington, TX 76011 P. O. Box 61867 Houston, TX 77208 George Dick, Project Manager U.S. Nuclear Regulatory Commission INPO Washington, DC 20555 Records Center 1100 circle 75 Parkway J. I. Tapia Atlanta, CA 30339-3064 Senior Resident inspector c/o U. S. Nuclear Regulatory Dr. Joseph M. Hendrie i Commission 50 Be11 port Lane P. O. Box 910 Be11 port, NY 11713 l Bay City,'TX 77414 D. K. Lacker i J. R. Newman, Esquire Bureau of Radiation Control l Newman & Holtzinger, P.C. Texas Department of Health 1615 L Street, N.W. 1100 West 49th Street Washington, DC 20036 Austin, TX 78756-3189 R. P. Verret/D. E. Ward Central Power & Light Company P. O. Box 2121 Corpus Christi, TX 78403 J. C. Lanier/M. B. Lee City of Austin Electric Utility Deptrtment P.O. Box 1088 Austin, TX 78767 l-I R. J. Costello/M. T. Hardt-City-Public Service Board P. O. Box 1771 San Antonio, TX 78296 l-Revised 10/08/90 L4/NRC/

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Attachment:

ST HL-AE-3600 ,

, Page 1 of-2 l South Texas Project Electric Generating Station Unit 1 " i Docket No S17150-498 Supplemental Special Report j Regarding Two Nonvalid Failures of #12 Standby Diesel Generator on Aueust 29. 1990 t

- DESCRIPTION OF EVENT:

s j On August :29, 1990 Unit I was in Mode 1 at 100 percent power. At approximately 0115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />, #12 Standby Diesel Generator (SDG) was started in the emergency mode to satisfy Technical Specification surveillance i

. requirements. After release from the emergency mode the diesel tripped. This

~

trip was categorized as a nonvalid failure.

l" The diesel was again started in the emergency mode at 0127 hours0.00147 days <br />0.0353 hours <br />2.099868e-4 weeks <br />4.83235e-5 months <br /> following initial troubleshooting. Af ter releasing the SEK: from the emergency.

mode the diesel-again tripped. No remote or local alarms were received except ,

for_a green'11ght on the local panel which indicated a tripped condition.

This trip was also categorized as a nonvalid failure. These trips-are identical to previous nonvalid failures'on SDG #13 reported to the NRC on .

July 12, 1990 and August 10, 1990, reference letters ST-HL AE-3504 and L ST-HL-AE-3532 respectively.

As.in the previous trips, the problem was traced to-the 86S/69 relay.

The relay is held energized by a series of nonessential protective relays and shutdown push buttons. During troubleshooting, a point to point check indicated that the 86S/69 relay was not operating and the relay was

• L subsequently replaced. The vendor's recommended. life for this relay is ten

! years. The relay was manufactured in 1978. <

Maintenance was completed and the diesel was satisfactorily tested at

'1140 hours0.0132 days <br />0.317 hours <br />0.00188 weeks <br />4.3377e-4 months <br /> on August 29, 1990. SDG #12 was declared operable at 1159 hours0.0134 days <br />0.322 hours <br />0.00192 weeks <br />4.409995e-4 months <br />.

CAUSE OF EVENT:

The cause of these nonvalid failures is due to failure of the 86S/69 l relay to operate properly. It is likely that the failure of the relay is due to age.

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Attachment-ST-HL AE 3600 :

Page 2 of 2 ANALYSIS OF EVENT:

The two events are classified as nonvalid failures since SDG #12 operated satisfactorily in the emergency mode and if challenged would have performed its safety function. The SDG trip circuits which actuate relay 86S/69 are bypassed in the emergency mode of operation.

CORRECTIVE ACTIONS:

1. Each SDG utilizes one hundred ten (110) 125 VDC GPDR control type relays manufactared by Amerace Corporation, forty seven of these relays are class 1E and the remainder are non class 1E. ' Replacement relays have been ordered for each Unit 1 diesel. The relays are expected to arrive in October 1990 and are scheduled to be installed in the train outages following receipt of the relays. Installation of the relays should begin on October 15, 1990, and should be-completed no later than June 1,1991. The class 1E relays in the

\ Unit 2 diesels were replaced during the start-up of the Unit, the remaining non class 1E relays will be replaced as schedule permits.

Routine monthly surveillance testing of the diesels will be sufficient to detect failure of the relays to operate properly. To date, there have been no valid failures of a diesel at South Texas Project Electric Generating Station which can be attributed to failure of an Amerace relay due to age.

2. Preventative Maintenance activities have been developed to replace the class 1E Amerace relays which were identified above at ten year' intervals. Additional preventative maintenance activities will be developed for the non-class 1E relays by December 31,-1991.

6 M lTIONAL INFORMATION:

Per STPEGS Technical Specification 3.8.1.1, there have been no valid failures in the last 20 valid tests of SDC #12 and the number of valid-failures in the last 100 valid tests is less than four (4), therefore, the testing frequency for SDG #12 remains at once per 31 days.

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