ML17326A464

LER 79-067/03L-0:on 791221,after Update of Axial Power Distribution Monitoring Sys Fz Setpoints,Two of Four Thimbles Used Found Lacking Lowest Sigma.Caused by Personnel Error in Readout.Fz Recalculated Using Correct Thimbles

ML17326A464
Person / Time
Site:	Cook
Issue date:	01/16/1980
From:	Delong S INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17318A570	List: ML17318A569 ML17326A463 ML17326A464
References
LER-79-067-03L, LER-79-67-3L, NUDOCS 8001220547
Download: ML17326A464 (3)

Text

NRC FORM 366 t7.77' t

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QF U. S. NUCLEAR REGULATORY COMMISSION

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68 69 2 2 1 EVENT DATE 7 9 74 Qs 0 75 I I 6 REPORT DATE 9 0 80 Qs EVENT DESCRIPTION AND PROBABLE CONSEQUENCES &IO AFTER THE APDMS F SETPOINTS WERE UPJIATED IT WAS FOUND THAT TWO OUT OF THE FOUR THIMBLES USED WERE NOT THE ONES WITH THE LOWEST UNCERTAINTY (SIGMA) FOR R THIS CONDITION WAS INCONSISTENT WITH T.S. 3.3.3.6 ITEMS a AND b.

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~79 21 22 EFFECT

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47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS Q27 o THE SELECTION OF THE WRONG THIMBLES WAS DUE TO THE PERSONNEL INVOLVED READING THE THIMBLE SIGMA DATA FROM THE WRONG COLUMN ON THE COMPUTER PRINTOUT. A COLUMN OF SIGMA DATA WITH A LOWER BOUND OF 2 PERCENT WAS USED.

1 3 THE THIMBLES THAT WERE INCORRECTLY SELECTED FOR DETECTORS 1 AND 2 HAD SIGMAS 4 OF 1.9 PERCENT. THE LOW UNCERTAINTY THIMBLES THAT SHOULD HAVE (SEE SUPPLEMENT) 7 8 9 80 METHOD OF

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TYPE 12 I Q" DESCRIPTION Q39 13 80 PERSONNEL INJURIES NUMBER DESCRIPTIONQ41 s ~00 0 Qso NA 7 8 9 11 12 80

'ZPEQ42 LOSS OF OR DAMAGE TO FACILITY Q43 NA 7 8 9 10 80 ISSUED PUBLICITY DESCRIPTION ~ NRC USE ONLY ss a

r 7 8 9 10 68 69 80 a S. D. DeLong 616-465-5901 0 IL NAME OF PREPARER sa

SUPPLEMENT TO LER ¹ 79-067/03L-0 SUPPLEMENT TO CAUSE DESCRIPTION BEEN USED FOR THESE DETECTORS HAD SIGMAS OF 0.6 PERCENT AND 1.1 PERCENT RESPECTIVELY. DURING THIS TIME THE THIMBLES SELECTED FOR DETECTORS 3 AND 4 WERE CORRECT. THEREFORE, ONE APPROPRIATE DETECTOR WAS ALWAYS BEING USED TO MONITOR CORE PERFORMANCE.

THE PROBLEM WAS DISCOVERED IN 2~~ HOURS AND F RECALCULATED USING THE CORRECT THIMBLES. THE F MARGINS WERE REDUCED FROM +15.9 PERCENT TO +14.5 PERCENT Z

AND +17.4 PERCENT TO 15.5 PERCENT FOR DETECTORS 1 AND 2 RESPECTIVELY.

THIS ERROR WAS DISCUSSED WITH THE INDIVIDUAL INVOLVED AND A TRAINING SESSION WAS CONDUCTED WITH ALL SECTION PERSONNEL IN ORDER TO PREVENT A REOCCURRENCE.