ML20246M389

Safety Evaluation Supporting Util 890317 Proposed long-term Solution to Correct Rust Problems in Containment Spray Headers

ML20246M389
Person / Time
Site:	Browns Ferry
Issue date:	05/09/1989
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20246M382	List: ML20246M377 ML20246M389
References
NUDOCS 8905190116
Download: ML20246M389 (2)

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f ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CONCERNING RUST IN LOWER CONTAINMENT SPRAY HEADER DUE TO LEAKING ISOLATION VALVES TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2 AND 3 DOCKET NOS. 50-259/260/296 ,

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1.0 INTRODUCTION

The Tennessee Valley Authority (TVA or the licensee) submitted Licensee Event Report (LER) 88-003-000 concerning the presence of rust in the lower containment spray header (LCSH) at Browns Ferry Nuclear Plant, Unit 2. The staff issued a Safety Evaluation dated December 20, 1988, which concluded that performance of the conmiitted work was satisfactory for short-term resolution of this problem.

However, long-term measures to prevent or mitigate the possible occurrence of excessive rust in both headers (and those of Units 1 and 3) in the future needed to be established should the isolation valves develop leaks.

By letter dated March 17, 1989, TVA reported that it had completed its commitment to clean (hydrolazing) the rust from the header, measure wall thickness of the lower header to assure structural integrity, and rework the inboard and the outboard isolation valves. Rework involved machining the valve discs and installing new seat rings in the inboard valve. Both valves passed their leak rate tests.

As a long-term measure, TVA committed to perform a visual inspection of the Unit 2 LCSH 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 of the respective unit. If no rust problems are found, the LCSHs will be inspected approximately every five years at the appropriate outage.

2.0 EVALUATION TVA has restored the LCSH and its nozzles to full operational efficiency, and provided adequate assurance of the lower header's structural integrity and the leak tightness of the isolations valves for the near term. The staff finds TVA' alanned actions of in-service inspections of the LCSH for each unit prob J t adequate long-term measures to detect damage caused by leaking isolation valves.

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3.0 CONCLUSION

Based on TVA's commitment to perform the above described inspections, the staff

' considers'the open item concerning the long-term measures for preventing or

' mitigating rust in the lower containment spray headers to be closed. ,

Principal Contributor: D. Smith Dated: May 9, 1989 4

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