ML19242A496

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Final Deficiency Rept Re Incorrect Orifice Size of Seal Water Injection Flow Elements Initially Reported 790607. Caused by Misinterpreted Drawings from Westinghouse.Correct Orifices Will Be Installed & Seal Injection Flow Rebalanced
ML19242A496
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 07/05/1979
From:
TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19242A495 List:
References
NUDOCS 7908020455
Download: ML19242A496 (1)


Text

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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 During preoperational testing in Unit 1 it was found that the seal water injection flow elements have an orifice size larger than specified by the NSSS design. This deficiency resulted from a confusion over Westinghouse 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 The original drawing showing the instrument tag numbers was partially superseded by a different later drawing.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 by TVA. Since the discrepancy between the two drawings was not discovered 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 exchangerIfis the isolated and orifices flow is sent to the boron injection tank and the RCP seals.

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 In Unit ? the correct orifices will be installed and the f asw elements will be recallurated before fuel loading. The seal injection flows will be rebalanced after initial heatup.

The orifices in Unit 2 will be checked to determine if the proper size was installed.

If the wrong size orifices were Installed in Unit 2, the 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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