ML19308A593

LER 79-009/03L-0:on 790429,switch Trip Positions Found at Greater than 10% of MSIV Closure.Caused by Failure to Set Field Calibr for Switch Trip Point Limit.Switches Were Adjusted to 10% Closure or Less

ML19308A593
Person / Time
Site:	Quad Cities
Issue date:	05/11/1979
From:	COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
LER-79-009-03L-05, LER-79-9-3L-5, NUDOCS 7911160416
Download: ML19308A593 (2)

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• EVENT DESCRIPTION AND PROBA9LE CONSEQUENCES h 10 of chel 12 l l While measuring the MSIV limit switch trip positions durina a weekend outaae.

,;3; g 12 switches measured on 6 MSIV's were found to be set greater than 10% of MSIV closure.1 The I j 3g4;  ; These measurements were performed at the request of NRC Inspector G. Vright.

1 g 10% closure settings were originally set at the factory prior to installatten and s y3j 3 9 yl unit startup. Montihly MStV closure scram functional testing has been performed to

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3 j 7 l l verify scram function operability. The remaining 2 MSIV's will be checked at a I

, ,, , , future outage of suf ficient length. 80 COMP. VALVE SYSTEM CAUSE CAUSE SUSCODE SUBCCDS COOE CODE SUSCODE COMPONENT COOE I i l A \h [pjh [C_j@ l 1 I N ] S I T l R I U lh I Slh [Zj h 3191 12 33

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47 sa si 4: 42 I 22 24 ss cAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i l O l ] The need for prior precise field calibration of the exact 1imit swi *ch Prin mine had I

s igii lnot been deemed necessary to be performed. A special procedure was developed to erablel As-found and corrected l

,,,, yexact measuring of"the switch trip position in the field.

The switches wer'e', adjusted tog 10% closure and j

,,3j l switch positions are attached.

- l i , , , l functionally tested. 80 8 3 9 SCO RY DISCOVERY OESCM'PTION ST  % POWER OTHE R STATUS #~

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HSIV LlHIT SWITCH TRIP POSITIONS ,

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SCRAM CHANNEL "B" SCRAM CHANNEL "A" .

INBOARD VALVES

. as found corrected  % error valve number ,as found corrected'.% error .

14.4% 8.2% 4.4%

14.5% 9.6% 4.5%

2-203-1A ~

16.0% 8.4% 6.0%

18.0%- 9 4% 8.0%

2-203 18 13.5% 8.5% 3.5%  !

11.3% 8.8% 1.3% l 2-203-1C '

6.0% 12.7% 8.8% 2.7%

2-203-1D 16.0% 9.8% ~

SCRAM CHANNEL "B" CUT 80ARD VALVES SCRAM CHANNEL "A"

% error as found corrected  % error

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as found corrected

s. salve number" 10.8% 11 7%' 6.9% 1.7%

20.8%, 8.5%

2-203-2C 6.0% 7.9% 0.0%

4.9% 8.9% 0.0%

2-203-2D

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