05000271/LER-1979-032-03, /03L-0:on 791204,Seismic Class I Hanger CST-HD19B Found to Be Damaged & Inoperable During Review Per IE Bulletin 79-02.Cause Under Investigation.Hanger Replaced & Design Changes Are Being Tested

/03L-0:on 791204,Seismic Class I Hanger CST-HD19B Found to Be Damaged & Inoperable During Review Per IE Bulletin 79-02.Cause Under Investigation.Hanger Replaced & Design Changes Are Being Tested

ML19260C739
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	01/02/1980
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19260C738	List: 05000271/LER-1979-032, Forwards LER 79-032/03L-0 05000271/LER-1979-032-03, /03L-0:on 791204,Seismic Class I Hanger CST-HD19B Found to Be Damaged & Inoperable During Review Per IE Bulletin 79-02.Cause Under Investigation.Hanger Replaced & Design Changes Are Being Tested
References
IEB-79-02, IEB-79-2, LER-79-032-03L, LER-79-32-3L, NUDOCS 8001080554
Download: ML19260C739 (2)

LER-1979-032, /03L-0:on 791204,Seismic Class I Hanger CST-HD19B Found to Be Damaged & Inoperable During Review Per IE Bulletin 79-02.Cause Under Investigation.Hanger Replaced & Design Changes Are Being Tested

Event date:
Report date:
2711979032R03 - NRC Website

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VTVYS1 05000271 LER 79-32/3L Event Description and Probable Consequences During the continuing ef? ort to determine and insure the adequacy of the Seismic Class I hangers, as described in NRC Bulletin 79-02, hanger CST-HD 19B was found damaged and inoperable.

This hanger was previously verified intact and operable during a recent inspection. Tech. Spec.

Section 3.6.I.1 requires that all seismic hangers be operable during power operation (based on interpretation associated with R0 79-15).

As allowed by Tech. Spec. Section 3.6.I.2, this hanger was repaired within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> time period. There have been no similar occurrences reported to the commission.

Cause Description and Corrective Action The cause of the occurrence is presently under investigation.

Although not conclusive, the failure of the hanger is attributed to water hammer developed during full flow surveillance testing of associated safety systems. The hanger was immediately replaced with a design which allows additional movement in the axial direction.

Other additional measures were also taken to further minimize the possibility of any damage.

Upon completion of further testing and inspection, corrective actions will be taken as necessary. A revision to the r jort will be submitted at that time.

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