ML20211H795

Special Rept:On 970828,EDG Failure Occurred Due to Fuel Oil Leak on Fuel Oil Return Header Tube at Number Four Cylinder. Interim Repair Performed by Removing & Replacing Damaged Section of Tubing

ML20211H795
Person / Time
Site:	Limerick
Issue date:	09/29/1997
From:	Boyce R PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9710070137
Download: ML20211H795 (3)

Text

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Robert W. Boyce Plant Manager j A Lmanck Generating Staten v

PECO NUCLEAR nco %v c-e, A dnit of PECO Energy 23Y Sanatoga. PA 19464 0920 610 718 2000 T.S. 6.9.2 September 29, 1997 Docket No. 50-353 License No. NPF-85 U.S. Nuclear Regulatory Commission 1 Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Limerick Generat.ing Station, Unit 2 Special Report for a Valid Emergency Diesel Generator Test Failure

REFERENCE:

Technical Specifications Sections 4.8.1.1.3 and 6.9.2 I

This Special Report is - submitted pursuant to the requirements of Technical Specifications (TS) Section 6.9.2 as required by TS Surveillance Requirement 4.8.1.1.3 TS Surveillance Requirement '

4.8.1.1.3 requires reporting of all diesel generator failures, valid

.or non-valid, within 30 days. The report is required to include the information Guide recommended in Regulatory Position C.3.b of Regulatory (RG) 1.108, "

Periodic Testing of Diesel Generator Units as Onsite Electric Power Systems at Nuclear Power Plants," Revision 1, August 1977.

G.' August 28, 1997 at 1102 hours, Operations personnel were performing the D21 Emergency Diesel Generator (EDG) Surveillance Test (ST) procedure ST-6-092-311-2, "

Start Operability D21 Diesel Generator Slow Q Test Run." The D21 EDG was started satisfactorily with all engine parameters within specification.

The Main Control Room. (MCR) Operator then synchronized the EDG to / --

the offsite source at.d began a controlled ramp up to full load as p' -

required by the ST procedure.

As this action was implemented, the J Equipment Operator (EO) and the System Manager walked down the D21 EDG to assure all components were operating properly. As EDG load reached 300 Kw, the EO identified a fuel oil leak on the fuel oil return header tube at the number 4 cylinder (opposite the control sica). The EO immediately notified the MCR and the System Manager

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of the situation. The System Manager placed a rag over the area to contain-any spray as a precaution against a fire. Concurrently, the MCR-Operator decreased load, secured the D21 EDG at 1111 hours0.0129 days <br />0.309 hours <br />0.00184 weeks <br />4.227355e-4 months <br />, DR D l .

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'Scptcmbar 29, 1997 Page 2 of 3 and placed the EDG in ' PULL TO LOCK' to prevent an inadvertent start. Operations. applied a Clearance to isolate the D21 EDG Fuel Oil System and commence investigation of the problem.

An investigation revealed the leak was caused by vibration induced rubbing between the fuel oil return header (a copper coated carbon steel tube) at the number 4 cylinder and a Jacket Water pipe elbow.

This resulted from a loose tubing support that allowed the tubing to drop and make contact with a Jacket Water pipe elbow.

The following immediate corrective actions were performed:

1. damaged An interim repair was performed by removing and replacing the section of tubing. The replaced tubing was then successfully pressure tested.

2. All similar tubing supports on the D21 EDG were inspected and adjusted / tightened as necessary to assure that the tubing is not free to rub on adjacent components.

3. A walkdown of the other seven Unit 1 and Unit 2 EDGs was performed to assure that a similar condition does not exist.

Several supports were observed slightly locse with some rubbing between the return tubing and the adjacent Jacket Water elbow.

Further inspections of the tubing determined that no breach of pressure boundary exist and the tubing rubs present no operability concerns for the EDGs. The supports were repositioned and tightened to prevent further contact.

4 . An evaluation concluded that the subject tubing support is a vendor unique design, and therefore, a common configuration does not exist throughout the plant.

On August 29, 1997 at 0041 hours4.74537e-4 days <br />0.0114 hours <br />6.779101e-5 weeks <br />1.56005e-5 months <br />, the D21 EDG was tested in accordance with_ procedure ST-6-092-311-2. The run was successfully completed and at 0310 hours0.00359 days <br />0.0861 hours <br />5.125661e-4 weeks <br />1.17955e-4 months <br /> the D21 EDG was declared operable.

The following future corrective actions are planned:

1. The interim repair of the D21 EDG fuel oil return header tube will be replaced with a single piece of tubing during the next scheduled EDG overhaul.

2.An assessment of the subject EDG tubing supports will be performed. This assessment will investigate the modification / replacement of the tubing support with a device that will provide a more positive clamp of the tube and prevent rotation of the support. Corrective measures from this assessment will be implemented as necessary.

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< Scptember 29, 1997 Page 3;of 3

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This event August  : 1977,was-reviewed using'the-guidance of RG-1.108, Revision 1,-

Section - C.2.e (S) with respect to EDG failures. The fuel oil leak 'resulted in a valid test -failure of the - D21 EDG.

Since this is the third test fe.ilure for the D21 EDG in the last 20 valid demands, the ST procedure - - monthly frequency is required to remain weekly in accordance with TS Section 4.8.1.1.2.a.

For additional information,. please contact Mr. Timothy A. Moore at (610)-718-3400.

Very truly yours,

{

IMS/JWB-cc: H. J. Miller, Administrator Region I, USNRC A. L. Burritt, USNRC Senior Resident Inspector, LGS F

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