05000334/LER-1977-006-01, /01T-1 on 770126:review of Pipe Stress Due to Feedwater Line Vibrations Noted Six Seismically Inadequate Snubbers on Feedwater Lines.Caused by Poor Design Verification During Plant Const
| ML19274E232 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/14/1979 |
| From: | Werling J DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| Shared Package | |
| ML19274E231 | List: |
| References | |
| LER-77-006-01T, LER-77-6-1T, NUDOCS 7903210005 | |
| Download: ML19274E232 (2) | |
| Event date: | |
|---|---|
| Report date: | |
| 3341977006R01 - NRC Website | |
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REPORT DATE 80 EVENT OESCalPTION ANO PROB ABLE CONSEQUENCES h o 2 l During a review of pipe stresses resulting from feedwater line vibrations, six l
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CAUSE OESCRIPTION ANO CORRECTIVE ACTIONS h i o l The incident resulted from breakdown of desien verification during plant I
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NAME OF PREPARER PHONE:
Attachment to LER 77-6/01T Boavar Valley Power Station Duquesne Light Company Docket No. 50-334 During a review by the Beaver Valley Architect / Engineer of pipe stresses resulting from feedwater line vibrations, it was discovered that six hydraulic snubbers installed on three feedwater lines inside containment are not adequate for seismic design condition. As a result of the discovery, an investigation was undertaken to review all Category I safety related snubbers and hangers to verify their conformance to requirements. The investigation revealed an additional twenty-six mechanical hangers whicn required modifications ranging from increasing the size of the anchor bolts to the addition of a new hanger at approximately the same location as an underdesigned hanger to carry some of the load.
In no case was any welding or other metallurgical change to the piping required to make these modifications.
The incident resulted from a breakdown in design verification procedures used during plant construction. Duquesne Light engineering personnel have reviewed the A/E calculational method for the redesigned hangers and have found them accepcable.
When the modifications were completed, the Onsite Safety Committee reviewed the incident and corrective actions and concurred that modifications were acceptable.