ML19276F588

Final Deficiency Rept:Movement of Steel Containment Vessel Was Not Accounted for in Design of Supports for Small Lines Penetrating Shield Bldg.Designs Are Under Analysis & Supports Will Be Redesigned

ML19276F588
Person / Time
Site:	Sequoyah
Issue date:	03/07/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19276F584	List: ML19276F583 ML19276F588
References
NUDOCS 7904060252
Download: ML19276F588 (1)

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ENCLOSURE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 ERROR IN DESICN OF SMALL LINE SUPPORTS NCR SWP 79-S-1 FINAL REPORT Description of Deficiency Movement of the Steel Containment Vessel (SCV) was not accounted for in the design of supports for several small lines that penetrate the Shield Building and the SCV. Since these supports were improperly designed, any thermal or pressure movement due to a LOCA could cause a pipe break or damage to the integrity of the SCV. Approxi=ately 35 containment penetrations are involved in each unit.

Safety Implications Had this condition remained uncorrected, LOCA-induced movement of the SCV could cause a break in safety-related piping or a loss of containment integrity of the SCV. Thus, under LOCA conditions, the safe operation of the plant could have been adversely affected.

Corrective Actions The s=all lines are being analyzed with the proper SCV movements accounted for, and supports will be redesigned and installed as required by this analysis. Design and installation of these supports will be completed before fuel loading of the associated unit.

Action Taken to Prevent Recurrence All piping penetrating containment that has not already been rigorously analyzed will be reviewed to ensure that proper support types and loca-tions have been used. The similar supports at Watts Bar Nuclear Plant have not yet been installed. An engineering change notice has been written to ensure proper installation at Watts Bar.

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