05000498/LER-2002-004, For South Texas Unit 1 Steam Generator Power Operated Relief Valve Failed to Close on Demand

For South Texas Unit 1 Steam Generator Power Operated Relief Valve Failed to Close on Demand

ML030350003
Person / Time
Site:	South Texas
Issue date:	01/27/2003
From:	Halpin E South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-03001460, STI: 31546798 LER 02-004-00
Download: ML030350003 (6)

LER-2002-004, For South Texas Unit 1 Steam Generator Power Operated Relief Valve Failed to Close on Demand

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
4982002004R00 - NRC Website

text

Nuclear Operating Company S

kuhTmfieed&,* Gwmt 5bi PO Bhr 2V W5.Zwffi To74 January 27, 2003 NOC-AE-03001460 File No.: G25 10CFR50.73 STI: 31546798 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Unit 1 Docket No. STN 50498 Licensee Event Report 02-004 Steam Generator Power Operated Relief Valve Failed to Close on Demand Pursuant to 10CFR50.73(a)(2)(i)(B) and 10CFR 50.73(a)(2)(vii), the South Texas Project submits the attached Unit 1 Licensee Event Report 02-004 concerning the failure of Steam Generator Power Operated Relief Valve lB to close on demand due to the tripping of the actuator hydraulic pump motor's thermal overload relay. The investigation found that the thermal overload heater, which had been installed by a plant modification, was undersized for this motor in this application.

This event did not have an adverse effect on the health and safety of the public.

Corrective actions number 4,5 and 6 are the only commitments contained in this event report.

If there are any questions on this submittal, please contact W. R. Bealefield, Jr. at (361) 972-7696 or me at (361) 972-7849.

E. D. Halpin Plant General Manager Attachment: LER 02-004 (South Texas, Unit 1)

NOC-AE-03001460 Page 2 of 2 cc:

(paper copy)

(electronic copy)

Ellis W. Merschoff Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Richard A. Ratliff Bureau of Radiation Control Texas Department of Health 1100 West 49th Street Austin, TX 78756-3189 Cornelius F. O'Keefe U. S. Nuclear Regulatory Commission P. O. Box 289, Mail Code: MN116 Wadsworth, TX 77483 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP L. D. Blaylock/W. C. Gunst City Public Service Mohan C. Thadani U. S. Nuclear Regulatory Commission R. L. Balcom Texas Genco, LP A. Ramirez City of Austin C. A. Johnson AEP Texas Central Company Jon C. Wood Matthews & Branscomb C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704

Abstract

On November 20, 2002, Unit 1 was in Mode 3 at 0% power. Unit 1 was being maintained in Mode 3 due to equipment failure in the Circulating Water system which required the main condenser to be taken out of service. The Steam Generator (SG) Power Operated Relief Valves (PORV) were being used to control decay heat removal from the primary plant. Plant operators attempted to close PORV 1 B in manual control and the valve failed to close. Investigation revealed that the thermal overload on the breaker supplying power to the actuator hydraulic pump for the PORV 1 B had tripped. The thermal overload was reset and PORV 1 B fully closed. Due to obsolescence of various Class 1 E Motor Control Center (MCC) sub-components, the Class 1 E MCC buckets are being replaced with new buckets and sub-components.

The MCC components for the PORV 1 B were replaced in 2000 under the plant modification process. The replacement bucket for the PORV 1 B contained a heater element rated at 114% of the motors maximum operating current. The STP design requirement for this heater in this application is a rating between 125%

and 140% of motor maximum operating current. Two PORV's in Unit 2 also had replacement buckets with heater elements undersized for this application. The breakers with under sized heater elements have been replaced. Additional training will be provided for engineering personnel on procurement practices.

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2.

Replaced the breakers for the Unit 2 PORVs with units having a 127% margin.

Completed November 26, 2002.

3.

Replaced the thermal overload heaters in other MCCs affected by the MCC modification.

Completed December 7, 2002.

4.

Design engineering personnel will be trained on the correct usage of the GE guidelines and table for selecting overload heater elements.

This corrective action will be completed by February 15,2003.

5. Training will be developed for engineering personnel on "Procurement of Engineered Materials."

This corrective action will be completed by August 31, 2003.

6. The setpoint index will be updated for safety-related components to add information necessary for sizing breaker components.

This corrective action will be completed by December 18, 2003.

ADDITIONAL INFORMATION

This event was determined to be reportable on November 28, 2002.

A search of the STP Equipment History found that there have been six other incidents related to MCC breaker overloads. None of these other incidents was reportable under 1 OCFR 50.73.