ST-HL-AE-4166, Special Rept:On 920630,CR Annunciator Lamp 22M01 Window F-1, Isolation Valve Cubicle Temp High Alarmed.Caused by Train D Cubicle Temp.Investigation Into Root Cause Ongoing

Special Rept:On 920630,CR Annunciator Lamp 22M01 Window F-1, Isolation Valve Cubicle Temp High Alarmed.Caused by Train D Cubicle Temp.Investigation Into Root Cause Ongoing

ML20099C129
Person / Time
Site:	South Texas
Issue date:	07/29/1992
From:	Jump W HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-4166, NUDOCS 9208030319
Download: ML20099C129 (5)

Text

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' The Light c o mp a ny South Texas Projnt Electric Genn at'ng P. O.6Box ation 289 Wadsworth. Texas 77483 llouston Lighting & Power _

July 29, 1992 ST-HL-AE-4166 File No.: G02 10CFR30.36 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Unit 1 Docket No. STN 50-498 Special Report Regarding an Evaluation of the Unit 1 Isolation Valve Cubicle Mich Temperature Condition on June 30. 1992 Pursuant to the South Texas Project Electric Generating Station Technical Specifications 3.7.13.b, Houston Lighting & Power submits the attached Special Report regarding an evaluation of the Unit 1 Isolation Valve Cubicle high temperature condition on June 30, 1992.

If ;ou should have any questions on this matter, please contact Mr. C. A. Ayala at (512) 972-8628 or me at (512) 972-7205.

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=f William J. Julhp General Manager, Nuclear Licensing JMP/ag

Attachment:

Special Report Regarding an Evaluation of the Unit 1 High Temperature Condition on June 30, 1992 300062 SREP\92-199.001 /

A Subsidiary of Houston Industries incorporated )

9208030319 920729 PDR

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flouston Lighting & Power Company South Ten- Project Electric Generating Station S HL 4166

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Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission -Associate General Counsel 611 Ryan Plaza Drive, Suite 400 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, GA 30339-3064 Senior Re61 dent Inspector c/o U. S. Nuclear Regulatory Dr. Joseph M. Hendrie Commission 50 Bellport Lane P. O. Box 910 Bellport, NY 11713 Bay City, TX 77414 D. K. Lacker J. R. Newman, Esquire Bureau of Radiation Control Newman & Holtzinger, P.C. Taxas Department of Health 1615 L Street, N.W. 1100 West 49th Street Washington, DC 20036 Austin, TX 787F0-3189 D. E. Ward /T. M. Puckett Central Power and Light Company P. O. Box 2121 Corpus Christi, TX 78403 J. C. Lanier/M. B. Lee City of Austin Electric Utility Department P.O. Box 1088

-Austin, TX 78767 K. J. Fiedler/M. T. Hardt City Public Service Board P. O. Box 1771 San Antonio, TX 78296 Revised 10*11/91 L4/NRC/

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1 Attachment ST-HL-AE-4166 Page 1 of 3 i

South Texas Project Unit 1 Docket No. STN 50-498 Special Report Regarding an Evaluation of the Unit 1 Isolation valve cubicle Hioh Temperature Condition on June 30. 1992 i

I. DESCRIPTION OF EVENT:

On June 30, 1992, Unit 1 was in Mode 1 at 100 percent power.

At approximately 0838 hours0.0097 days <br />0.233 hours <br />0.00139 weeks <br />3.18859e-4 months <br />, Control Room annunciator lamp

22M01 window F-1, " ISOLATION VALVE CUBICLE TEMPERATURE HIGH",

alarmed. Using tha Emergency Response Facility Data

' Acquisition Display System (ERFDADS) computer, it was determined that the Train D cubicle temperature had caused the alarm. Local temperature readings in the cubicle were 95 F .

A temporary log was initiated to monitor the Isolation Valve Cubicle (IVC) Train D cubicle temperature at the 10' Elevation. At approximately 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on June 30, 1992, the temperature exceeded 101 F by local temperature probe reading. A Limited Condition for Operation (LCO) 3.7.13 was entered. At 2030 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.72415e-4 months <br />, the cubicle temperature was recorded at 103. 9 F. The LCO was exited at approxinately 2340 hours0.0271 days <br />0.65 hours <br />0.00387 weeks <br />8.9037e-4 months <br /> on June 30, 1992, when the " ISOLATION VALVE CUBICLE TEMPERATURE HIGH" annunciator clenred, and local temperature was verified to be less than 101"F. The total time in which the temperature in the IVC exceeded 101P, was eight hours and ten minutes.

i Technical Specification 3.7.13, Area Temperature Monitoring, requires the IVC temperature at the 10' Elevation to be less than or equal to 101 F. If the IVC temperature exceeds 101*F for more than 8 hourc, LCO 3.7.13 Acticn b states that a Special Report,be prepared and submitted to the NRC within 30 days, pursuant to Technical Specification 6.9.2. The Special Report shall provide a record of the cumulative time and the amount by which the temperature in the affected area (s) exceeded the limit and an analysis to demonstrate the continued operability of the affected equipment.

SREP\92 199.001

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Attachment j ST-HL-AE-4166 Page 2 of 3 a

l South Texas Project Unit 1 Docket No. STN 50-498 Special Report Regarding an Evaluation of the Unit 1 Isolation Valve Cubicle l Hiah Temnerature Condition on June 30, 1992

, II. INVESTIGATION:

The area temperature in the IVC is maintained by the IVC Ventilation and Heating System. This system consis' . of four independent trains (A, B, C, and D). Each train terves the corresponding Auxiliary Feedwater (AFW) pump cubicle located at 10' Elevation and the asso:iated Main Steam Isolation Valve (MSIV) cubicle located above 34' Elevation. Each IVC ventilation train consists of one 100% capacity vano-axial supply fan and discharge duct for distribution. Each fan supplies outside air to the associated- pump and valve-cubicles. Discharge air is exhausted to the outside from a relief opening near the top of each valve cubicle. The fans are located on the roof of the IVC inside the missile walls.

In addition, there are a total of three electric unit heaters per train; one in the AFW pump cubicle and two in the MSIV cubicle.

Each of the four Isolation Valve Cubicles contains a valve cubicle and a pump cubicle. The valve cubicle contains the main steam safety valves associated with each steam generator, the main steam isolation valves, the atmospheric st w m relief valves and the main feedwater isolation valves.

The pump cubicle contains the three motor driven AFW pumps and the steam turbine driven (Train D) Auxiliary Feedwater pump and their associated equipment.

Based on the operator temporary logsheet, Train D pump c u b i c l e -'m a x i m u m temperature was 103. 9 F. The impact on qualified life of the motor-driven and turbine-driven AFW pumps and their associated' safety-related equipment would be minimal. The safety-related equ in the IVC ha's been environmentally qualified to 104,ipment F or Ligher.

SAEP\92 199.001

4 Attachment ST-HL-AE-4166 Page 3 of 3 South Texas Project Unit 1 Docket No. STN 50-498 Special Report Regarding an Evaluation of the Unit 1 Isolation Valve Cubicle liich Temperature Condition on June 30. 1992 '

II. V 1]iVLSJIGATION  : (Con't)

Since higher area temperatures are normally expected to occur during the summer months, Engineering performed a conservative evaluation to assess the impact of higher area temperature on the qualified life of safety-related-equ,ipment. The evaluation assumed an area temperature 'of 110 F and an exposure period of eight r eurs a day for the four summer months. The results of the evaluation indicated that the impact on the qualified life of safety-related equipment in the IVC is minimal. Therefore, the effects of the temperatures up to 110*F un qualified life or operability for a span of eight hours and ten minutes would be insignificant. In addition, since critical safety-related equipment in the valve cubicles are periodically tested per Technical Specification requirements, any signs of degradation could be detected in advance An investigation into the root cause of this event is currently ongoing. The investigation is being documented under Station Problem Report 920290 and will be available for review on site, once the investigation has been completed.-

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SREP\92-199.001

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