05000237/LER-1979-057-01, /01T-0:on 791019,while in Shutdown,Three of 16 MSIV Scram Limit Switches Found W/Setpoints Greater than 10%.Caused by Not Performing Field Calibr on Switch Setpoints Set by Manufacturer.Limit Switches Readjusted

/01T-0:on 791019,while in Shutdown,Three of 16 MSIV Scram Limit Switches Found W/Setpoints Greater than 10%.Caused by Not Performing Field Calibr on Switch Setpoints Set by Manufacturer.Limit Switches Readjusted

ML17174A114
Person / Time
Site:	Dresden
Issue date:	10/31/1979
From:	Korchynsky M COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17174A115	List: 05000237/LER-1979-057, Forwards LER 79-057/01T-0 05000237/LER-1979-057-01, /01T-0:on 791019,while in Shutdown,Three of 16 MSIV Scram Limit Switches Found W/Setpoints Greater than 10%.Caused by Not Performing Field Calibr on Switch Setpoints Set by Manufacturer.Limit Switches Readjusted
References
LER-79-057-01T, LER-79-57-1T, NUDOCS 7911060485
Download: ML17174A114 (3)

LER-1979-057, /01T-0:on 791019,while in Shutdown,Three of 16 MSIV Scram Limit Switches Found W/Setpoints Greater than 10%.Caused by Not Performing Field Calibr on Switch Setpoints Set by Manufacturer.Limit Switches Readjusted

Event date:
Report date:
2371979057R01 - NRC Website

text

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e Common&lth Edison Dresden Nudear Power Station R.R. #1 Morris, Illinois 60450

• Telephone 815/942-2920 October 31, 1979 BBS LTR /179-874 James G. Keppler, Regional Director Directorate of Regulatory Operations - Region III U.S. Nuclear Regulatory.Commission 799 Roosevelt Road Glen Ellyn, IL 60137 Reportable Occurrence Report 1179-57/0lT-0, Docket 11050-237 is hereby.submitted to your office ih accordance with Dresden Nuclear Power Station Technical*Specification 6.6.B.l:(a), failu:re of the reactor protection sys;tem or other.systems subject to limiting safety system settings to initiate the required protective function by the time a monitored parameter reaches the setpoint specified as the limiting safety system setting in the technical specifica-tions or failure to. complete the required protective *function.

BBS:lcg Enclosure f;~p~k11A Station Superintendent Dresden Nuclear Power Station cc:

Director of Inspection & Enforcement Director of Management Information & Program Control Ft1e/NRC

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EVENT DESCRIPTION AND PROBABLE CONSEQUE.NCES@

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BO C[I] fWhile in the S/D mode of operation the MSIV scram*limitswit'ches were checked.

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QI] I Of the 16 limit switches 3 were--found to have setpoints) 10%.. This event was

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I of minimal safety significance since the switches with setpoints.) 10% were all**

I located ori the inboard MSIV' s and all the outboard MSIV' s had setpoints..l...lQ~_ *'

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42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS I The Namco Snap Lock Limit Switch setpoints were* set by the manufacturer..The need* for ill] field calibration of the *exact limit switch tr.ip point did not seem necessary at the IITI time of installation.

The limit switches were readjusted and demonstrated operable.

I I1JJ I Unit 3 MSIV scram limit switches to be tested during the next refueling outage.

No

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ATTACHMENT TO LICENSEE~EVENT REPORT79-57/01T-O COMMONWEALTH EDISON COMPANY (CWE)

DRESDEN. UNIT ILDRS-2 DOCKET iJ 050-237 Quad Cities Station was requested by the NRC to check the *MSIV scram limit switch setpoints.

Several setpoints were not L.10% as required by Tech Spec

• Table 3.1.1.

While Dresden Unit 2 was in a S/D mode of operatiori, the MSIV scram limit switches were checked.

Of the sixteen (16) limit switches, three (3) were found tQ have setpoints highe~ than 10%.

MSIV 203-lA. had limit switch setpoints of 15% and 17%, while MSIV 203-lD had one (1) limit sw_itch with a set point of 10.3%.

This event was of minimal safety.significance since all the limit switches with high set points were located on the inboard MSIV's and all the outboard valves had limit switch setpoints of ~l0%. This is.the first event of this type at Dresden.

The Namco Controls Snap-.Lock Limit Switch set points were set by -the manu-facturer.

The need for field:calibration of.-the exact limit switch trip.point.

did not seem necessary.at the tiine *of.installation.* The.limit switches were re-adjusted and demonstrat~d operabre." -* The Unit 3 M.SIV s<;r?Jil limit switches will be similarly tested c,iuring F~*e. next refueling outage~.. No further action is, necessary.

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