05000348/LER-1979-054-01, /01T-0:on 791119,notified by Westinghouse That Possibility Exists That Current Negative Rate Trip Setpoints May Not Provide Reactor Trip During Single or Multiple Rod Drop Events.Caused by Designer Calculation Errors

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/01T-0:on 791119,notified by Westinghouse That Possibility Exists That Current Negative Rate Trip Setpoints May Not Provide Reactor Trip During Single or Multiple Rod Drop Events.Caused by Designer Calculation Errors
ML19262A942
Person / Time
Site: Farley Southern Nuclear icon.png
Issue date: 12/03/1979
From: Hairston W
ALABAMA POWER CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19262A938 List:
References
LER-79-054-01T, LER-79-54-1T, NUDOCS 7912110339
Download: ML19262A942 (1)
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LER-1979-054, /01T-0:on 791119,notified by Westinghouse That Possibility Exists That Current Negative Rate Trip Setpoints May Not Provide Reactor Trip During Single or Multiple Rod Drop Events.Caused by Designer Calculation Errors
Event date:
Report date:
3481979054R01 - NRC Website
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'i l Based on information presented to APCo by Westinehouse on 11/19/79. there exists the I

o la l possibility that current necative rate trio setpoints may not orovide a reactor trip I

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Also, when certain calc _ulations werd n !sl l repeated with conservative assumptions (previously calculated using non-conservative l

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l assumptions), results indicated that some drooped rod events without reactor trio could Q QJ [ result in violation of DNBR limits above 90% nower if the rod control system was in I

oinj iAutomatic and had sufficient rod worth available to compensate for the dropped rod (s). I s 9 This is a notential item of reportability under Tech. Spec. 6.9.1.8.h.

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CAUSt CCCRIPTION AND CO3RECTIVE ACTICNS h o lThe potential events described in item 10 can be attributed to deciener calg.glation

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l l case" multiple rod dron locations. Plant operating procedures have been revised to I

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