ML19208C819

Forwards Final Deficiency Rept Re Misalignment of Steel Containment Vessels

ML19208C819
Person / Time
Site:	Sequoyah
Issue date:	09/11/1979
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 7909270541
Download: ML19208C819 (1)

Text

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. TENNESSEE VALLEY AUTHORITY

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Mr. Janes P. O'Reilly, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Coc: mission '

Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303

Dear Mr. O'Reilly:

SEQUOYAH NUCLEAR PLANT UNIT 1 - FLEXIBLE BELLOWS PENETRATIONS OF STEEL CONTAINMENT VESSEL MISALIGNED DURING INSTALLATION - NCR 1666 -

FINAL REFORT The subject deficiency was initially reported to NRC-01E Inspector W. T. Cattle on May 25, 1979, in accordance with 10 CFR 50.55(e).

An interim report was submitted on June 25, 1979. Enclosed is our final report.

If you have any questions concerning this matter, please get in touch with D. L. Lambert at FTS 854-2581.

Very truly yours, TENNESSEE VALLEY AUTHORITY L. . Mills, Ma ager Nuclear Regulation and Safety Enclosure cc: Mr. Victor Stello, Jr., Director (Enclosure)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Coc:nission Washington, DC 20555 4; bk\1 3909 " O 1042 347 An Ecual Opportunity Employar

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. ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 1 FLEXIBLE BELLOWS PENETRATIONS OF STEEL CONTAINMENT VESSEL MISALIGNED DURING INSTALLATION NCR 1666 10 CFR 50.55(e)

FINAL REPORT Description of Deficiency During hot functional preoperational testing at unit 1 of Sequoyah Nuclesr Plant, removal of the bellows restraints on 32 bellows penetrations of the steel containment vessel (SCV). revealed that those bellows restraints were misaligned. This deficiency is considered reportable because three of the bellows penetrations might have leaked containment atmosphere to the annulus region (between the SCV and concrete containment) when subjected to the deflections associated with a postulated safe shutdown earth-quake (SSE) or design basis accident (DBA). The balance of the 32 bellows penetrations were analyzed by the manufacturer (Tube Turns, Louisville, Kentucky) and found to be acceptable with the present misalignment to operate a

when subjected to the deflections associated with an SSE or DBA without containment leakage.

The apparent cause of this deficiency is a faulty installation sequence that permitted the containment-to-bellows weld to be completed before making process pipe closure welds. Hence, slight misalignment of the piping resulted in misalignment of the bellows.

Safety Implications If this deficiency had remained uncorreccei, it is possible that 3 of 32 bellows penetrations might possibly have failed when subjected to the deflec-tions associated with a postulated SSE or DBA. In this context, a failure would be a small split in the bellows which would permit leakage of the containment atmosphere into the annulus area.

Corrective Actions TVA inspected all bellows penetration assemblies in the SCV and took align-ment data. The alignment data was analyzed by the bellows manufacturer.

Following analysis, the bellows manufacturer placed the bellows in three categories.

1. Those bellows (three in number) that analysis could not ensure would' survive their misalignment plus the deflections associated with a postulated SSE or DBA without the possibility of a leakage

2. Those bellows (15 in number) that analyses showed would survive their misalignment plus the deflections associated with a postulated SSE or DBA, but would require inspection before continued operation 1909o10339 1042 348

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'- 3. Those bellows (14 in number) that analyses showed would be completely satisfactory for 40 years life with their installed misalignment plus the deflections associated with a postul.ted SSE or DBA The three bellows which were not capable of surviving the deflections associated with a postulated SSE or DBA without possible leakage as installed were reinstalled. During the reinstallation process, no problem other than the misalignment was found. The proper installation sequence was strictly followed during reinstallation of these three bellows.

Feasurements made following reinstallation of two of these three bellows (X-33 and X-108) ensured that they would be completely satisfactory over 40 years of plant life. Measurements made on the other bellows (X-109) were i.nalyzed as being satisfactory with its misalignment to sutvive the deflections associated with a postulated SSE or DBA with a required inspection before continued operation.

Means Taken to Prevent Recurrence Sites where TVA has nuclear plants under construction have been requested to reemphasize to craft employees installing bellows that construction efficiency requires prorer alignment of piping and bellows nozzles before installation welding. The Sequoyah Nuclear Plant construction forces have a

appointed a technical supervisor to monitor the installation of all remaining bellows penetrations.

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