ST-HL-AE-2419, Final Part 21 & Deficiency Rept Re Inadequate Cooling of High Voltage Cubicle Panels for Standby Diesel Generators. Initially Reported on 870729.Design Mod to Provide Addl Cooling Completed & Drip Shields Over Vents Removed

Final Part 21 & Deficiency Rept Re Inadequate Cooling of High Voltage Cubicle Panels for Standby Diesel Generators. Initially Reported on 870729.Design Mod to Provide Addl Cooling Completed & Drip Shields Over Vents Removed

ML20236T353
Person / Time
Site:	South Texas
Issue date:	11/25/1987
From:	Goldberg J HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
REF-PT21-87, REF-PT21-87-199-000 PT21-87-199, PT21-87-199-000, ST-HL-AE-2419, NUDOCS 8712010167
Download: ML20236T353 (4)

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The Light company llouston Lighting & Power _ . "b"' #

November 25, 1987 ST-HL-AE-2419 File No.* G12.400, G2.2 10CFR50.55(e) i U. S. Nuclear Regulatory Commission Attention: Document Control Desk .

Washington, DC 20555 South Texas Project Electric Generating Station Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Final Report Concerning Cooling of the Standby Diesel Generator High Voltage Cubicle Panep )

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On July 29, 1987, Houston Lighting and Power Company notified your office, pursuant to 10CFR50.55(e), of an item concerning cooling of the Standby Diesel Generator high voltage cubicle panels. Enclosed is our Final l Report on this item. We have determined this item to be reportable pursuant to 10CFR50.55(e) and 10CFR21.

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

J. S. Phelps at (512) 972-7071.

1 J. H. Goldberg Group Vice President, Nuclear l

SDP/hg

Attachment:

Final Report Concerning Cooling of the Standby Diesel Generator High Voltage Control Panel 8712010167 871125 PDR ADOCK 05000498 g PDR

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ST-HL-AE-2419 Ilouston Lighting & Power Company . File No.: G12.400, G2.2 L Page 2 l cc:

Regional' Administrator, Region IV Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 N. Prasad Kadambi, Project Manager U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, MD 20814 Dan R. Carpenter Senior Resident Inspector / Operations c/o U.S.' Nuclear Regulatory Commission P. O. Box 910 Bay City, TX 77414 Claude E. Johnson Senior Resident Inspector / Construction c/o U.S. Nuclear Regulatory Commission P. O. Box 910 Bay City, TX 77414

.. R. Newman, Esquire Newman & Holtzinger, P.C.

1615 L Street, N.W.

Washington, DC 20036 R. L. Range /R. P. Verret l Central Power & Light Company P. O. Box 2121 Corpus Christi, TX 78403 R. John Miner (2 copies)

Chief Operating Officer City of Austin Electric Utility t 721 Barton Springs Road '

Aus tin, 1DC 78704 R. J. Costello/M. T. Hardt f City Public Service Board '

P. O. Box 1771 San Antonio, TX 78296 Rufus S. Scott Associate General Counsel Houston Lighting & Power Company P. O. Box 1700 Houston, TX 77001 1

Revised 11/20/87 {

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Attachment ST-HL-AE-2419 File No.: G12.400, C2.2 Page 1 of 2 Final Report Concerning Cooling of the Standby Diesel Generator High Voltage Cubicle Panels I. Summary On July 29, 1987, Houston Lighting and Power Company (HL&P) notified the NRC of an item determined to be potentially reportable pursuant to 10CFR50. 55 (e') . This item concerns inadequate cooling of the Unit 1 high voltage cubicle panels for the Standby Diesel Generators (SBDGs). During a 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> test run of SBDG 13, a high temperature alarm was actuated from the associated high voltage cubicle panels. HL&P has determined that additional cooling for these panels was required to ensure internal temperatures would not exceed the environmental qualification (EQ) temperature of certain safety related equipment within the panels. Had this deficiency been left uncorrected, the qualified life of the affected equipment could have been reduced due to the overheating of the panels.

Because such an event could have caused an adverse affect upon the safety of operations, HL&P determined this to be reportable pursuant to 10CFR50.55(e) and 10CFR21.

II. Description of Deficiency During a 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> test run of SBDG 13, a high temperature alarm actuated in the SBDG's high voltage cubicle panel. The alarm, which has a setpoint of 140 F, actuated at approximately twelve (12) hours into the test.

In response to'the high temperature alarm, the panel doors were opened to improve ventilation, and the test run was terminated. Thepanelscongain safety related equipment that is qualified up to a temperature of 158 F (70 C). The alarm setpoint of 140 F (60 C) includes allowances for instrument inaccuracies and local heating. HL&P has concluded that no degradation of the qualified life of safety related equipment occurred during this event.

III. Corrective Actions HL&P has completed a design modification to provide additional coolin5 for the Unit 1 panels. A second fan was installed in each panel opposite the originally installed fan. In addition, drip shields over the vents in the panels were removed to provide greater air flow capacity. A i review of the design of the panels concluded that no adverse effect on their operability will result from removing the drip shields.

After completion of the modification, another 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> test run of SBDG 13 was completed successfully.

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• Attachment ST-HL-AE-2419 File No.: G12.400, G2.2 Page 2 of 2 A similar modification to the Unit 2 panels will be completed prior to start-up testing. HL&P has reviewed the design of other STP control panels by Cooper and has determined that adequate cooling is provided.

IV. Recurrence Control STP has concluded that this cooling design deficiency is isolated to the SBDG high voltage cubicle panels. Adequacy of the cooling provided for-the other Cooper-supplied control panels was verified during the 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> SBDG test.

V. Safety Analysis Under test condicions, the high temperature alarm for the high voltage panel for SBDG 13 was actuated. This alarm sounds in the control rcom but does not trip the associated SBDG. Under actual accident conditions concurrent with a loss of offsite power, manual shutdown of the associated SBDG may not be practical in the event of a high temperature alarm. Therefore, with the unmodified design, the potential existed for temperatures inside the panels to exceed the EQ limit of 158 F. If the SBDG is not shut down, the qualified life of the safety related equipment within the panels would be reduced.

Although a detailed heat transfer study was not performed to determine potential peak temperatures which could occur within the vendor-supplied high voltage cubicle panels, HLAP has assumed that, had this deficiency not been corrected, it could have had an adverse effect upon the safety of operations, Therefore, this item was determined to be reportable l pursuant to 10CFR50.55(e) and 10CFR21.

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