ML19242A496
| ML19242A496 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/05/1979 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML19242A495 | List: |
| References | |
| NUDOCS 7908020455 | |
| Download: ML19242A496 (1) | |
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I ENCLOSURE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 SEAL WATER INJECTION FLOW ELDIENTS RAVE WRONG ORIFICE SIZE HCR MEB 79-21 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency the seal water During preoperational testing in Unit 1 it was found that injection flow elements have an orifice size larger than specified by the This deficiency resulted from a confusion over Westinghouse NSSS design.
supplied drawings. The original drawing showing the instrument tag numbers was partially superseded by a different later drawing. The change in the tag numbers was not noticed and both drawings were given approved status Since the discrepancy between the two drawings was not discovered by TVA.
by design or construction personnel, the orifice size on the original drawing was installed.
Safety Implications During normal operation these flow elements are umed to regulate flow to the Reactor Coolant Pump (RCP) seals. Under accident conditions the centrifugal charging pumps start, flow to the regenerative heat exchanger is isolated and If the orifices to the boron injection tank and the RCP seals.
flow is sent are too large, an excess flow would go to the RCP seals and an insufficient flow would go to the boron injection tank. Since the flow to the boron it would take longer to
- injection tank is then less than the design flow, inject the contents of the boron injection tank. Thus, the boron injection system would not perform as designed.
Correctiya Action the correct orifices will be installed and the f asw elements will In Unit ?
be recallurated before fuel loading. The seal injection flows will be rebalanced after initial heatup.
2 will be checked to determine if the proper size was The orifices in Unit If the wrong size orifices were Installed in Unit 2, the installed.
corrective action will also apply to Unit 2.
Action Taken to Prevent _, Recurrence To avoid r confusion over drawings in the future, Westinghouse has been requested to revise the original drawing instead of transmitting a new drawing which only partially supersedes the original drawing.
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