ML19210D168
| ML19210D168 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/25/1979 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML19210D165 | List: |
| References | |
| NCR-CEB-79-29, NUDOCS 7911200608 | |
| Download: ML19210D168 (1) | |
Text
ENCLOSURE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 ERCW ISOLATION VALVES NCT SE1SMICALLY QUALIFIED NCR CEB 79-29 10 CFR 50.55(e)
FINAL REPORT Description of Condition While reevaluating the design basis accident movements of the steel containment (as corrective action to NCR CEB 79-19) it was discovered that the containment isolation valves in the essential raw cooling water system are not seismically qualified.
A total of 12 valves in each unit are involved.
This condition is a result of a misinterpretation of the specification requirements on eeismic qualification.
When the valve manufacturer (Tufline Division of Xomox) submitted their contract bid it included a cover letter which stated that they did not interpret the specifications to require seismic qualification and therefore it would not be included in their bid.
However, TVA accepted the bid.
Safety Implications Had this condition gone uncorrected a seismic event could have led to a failure of these valves, which could have violated the containment integrity. Thus, the safe operation of the p,lant could have been adversely affected.
Corrective Action One of the valves was sent back to the manufacturer to determine what modifications would be necessary in ordet to seismically qualify the valves.
Subsequently, the valve manufacturer has designed, analyzed, and tested a valve operator support configuration that will enable the
alves to meet the seismic requirements.
These supports will be added to each of the valves before fuel loading of the respective units.
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'1911200
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