ML19269E583

First Interim Deficiency Rept:During Hot Functional Preoperational Testing,Removal of Bellows Restraints Revealed Misalignment.Caused by Faulty Installation Sequence.Bellows Reinstalled

ML19269E583
Person / Time
Site:	Sequoyah
Issue date:	06/25/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19269E567	List: ML19269E566 ML19269E583
References
NUDOCS 7906290316
Download: ML19269E583 (2)

Text

,

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

FIRST INTERIM REPORT Description of Deficiency During hot functional preoperational testing at Sequoyah Nuclear Plant Unit 1, removal af 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 penetra-tiens might have leaked containment atmosphere to the annulus region (between the SCV and concrete containment) following a postulated nominal safe shutdown earthquake (SSE) or a nominal 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 misalign-ment to operate following a nominal SSE or nominal DBA without containment leakage.

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

Safety Implications If this deficiency had remained uncorrected, it is possible that three of thirty-two bellows penetrations might possibly have failed during a nominal SSE or nominal 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 tech alignment data. The alignmant data was analyzed by the bellows manufacturer. Fcilowing 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 a nominal SSE or nominal DBA without the possibility of a leakage.

(2) Those bellows (fifteen in number) that analyses showed would survive their misalignment plus a nominal SSE or nominal DBA, but would require inspection before continued operation following a nominal SSE or nominal DBA.

(3) Those bellows (fourteen in number) that analyses showed would be completely satisfactory for 40 years life with misalignment following a nominal SSE or nominal DBA.

The three bellows penetrations that adalyses revealed to be unacceptab;e are being reinstalled with the proper alignment.

2146 068 4

q906290f/C

Means To Prevent Recurrence TVA is presently investigating the means that will be taken to prevent recurrence of this type of deficiency. These measures will be detailed in a subsequent report on this deficiency.

9 e

2146 069