ML20236E202

Responds to Request for Addl Info on Rust in Lower Containment Spray Header (Lcsh) of Unit 2.Nozzles in Lcsh Removed & Outboard Isolation Valve Repaired.List of Commitments Encl

ML20236E202
Person / Time
Site:	Browns Ferry
Issue date:	03/17/1989
From:	Gridley R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-00454, TAC-454, NUDOCS 8903240011
Download: ML20236E202 (4)

Text

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.e TENNESSEE VALLEY AUTHORITY ,

- CHATTANOOGA, TENNESSEE 37401 SN 1578 Lookout Place I MAR 171989 f

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk q Washington, D.C. 20555 o Gentlemen:

In the Matter of ) Docket Nos. 50-259 Tennessee Valley Authority ) 50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON RUST IN LOWER CONTAINMENT SPRAY HEADER OF UNIT 2 (TAC 00454)

Reference:

NRC-letter to 0. D. Kingsley, Jr. dated December 26, 1988,

" Browns Ferry, Unit 2, Rust in Lower Containment Spray Header."

In the above referenced letter, NRC provided its Safety Evaluation (SE) of TVA's corrective action after finding rust in the unit 2 Lower Containment Spray Header (LCSH). The SE concluded that the planned corrective actions would restore the LCSH and its nozzles to full operational efficiency, prevent leakage for the near term and' provide adequate assurance of the lower header's structural integrity. However, the SE requested that TVA provide additional information on the following:

1. Provide the results of measurements of the lower header's wall thickness and the adjustments or repair of the inboard and out'oard J isolation valves. ,

2. TVA's long-term measures to be taken to prevent or mitigate the occurrence of excessive rust in both the lower and upper headers (and those of units 1 & 3) in the future, should the isolation valves develop leaks.

TVA has removed and cleaned the nozzles in the LCSN and has repaired the outboard isolation valve which was the cause of the water accumulation in the lower header. A hydrolazer was used to remove the rust from the header and it was then visually inspected to insure that the rust had been removed. The unit 2 LCSH was calculated to need a minimum wall thickness of 0.33 inches.

From the ultrasonic testing the actual wall thickness was determined to be  !

0.556 inches, the resulting determination was that the wall thickness was acceptable, j

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Both the inboard and outboard isolation valves were disassembled and reworked.

The inboard isolation valve (2-FCV-74-60) required that the valve disc be machined to remove defects (about 0.041 inches removed) and then reinstalled j with new' seat rings. The outboard isolation valve (2-FCV-74-61) required that the valve disc be machined to remove defects (about 0.005 inches on the o'tboard u side were removed), the existing seat rings needed to be machined to I remove pitting (about 0.007 inches on one side and 0.001 inches on the other side). Both valves passed their leak rate testing.

As far as the Upper Containment Spray Header (UCSH) is concerned, no rust was found that would block the sparger holes of the spray nozzles. The LCSH were l looked at on both units 1 and 3 and no rust problem were discovered that could j block the sparger holes in either unit.

As a long-term measure TVA will perform a visual inspection of the unit 2 LCSH 4 during the next outage, and if no problems are found, the LCSH will be inspected every five years at the appropriate outage. TVA will also inspect the LCSH for units 1 and 3 before restart on the respective unit. If no rust [

problems are found, the LCSH will be inspected approximatately every 5 years at the approplate outage.

The enclosure contains a complete list of commitments made in this submittal.

If you have any questions, please telephone Patrick P. Carter, BFN Site '

Licensing, at (205) 729-3570.

Very truly yours, ,

TENNESSEE VALLEY AUTHORITY

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Regulatory Affairs l Enclosure cc: See page 2 ,

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U.S. Nuclear Regulatory Commission llfdk 17 f38@

cc (Enclosure):

Ms.'S. C. Black,; Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Ms. L. J. Watson, Acting Assistant Director  ;

for Inspection Programs j TVA Projects Division i U.S. Nuclear Regulatory Commission Region'II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Browns Ferry Resident Inspector Browns Ferry' Nuclear Plant Route 12,: Box 637 Athens, Alabama 35609-2000 '

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. . . . . . ik Enclosure y

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' List of Commitments- J

, The following is a list of commitments made in this submittal:

1

.l. TVA will perform a visual. inspection for rust on the unit 2 Lower ]

Containment Spray Header (LCSH) during the next-outage, j

2. The unit 2 LCSH will be inspected every five years'at-the appropriate outage.- ]

3. TVA will. inspect the LCSH for units 1 and 3 before restart on the respective unit.

4. The LCSH for unit 1 and 3 will be inspected every 5 years at the appropiate outage. -

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