ML20024A696

LER 83-051/03L-0:on 830516,reactor Protection Sys Trip Channel H2 Limit Switch Failed to Operate Properly.Cause Unknown.Limit Switch readjusted.W/830614 Ltr

ML20024A696
Person / Time
Site:	LaSalle
Issue date:	06/14/1983
From:	Diederich G, Houston R COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
LER-83-051-03L-01, LER-83-51-3L-1, NUDOCS 8306220064
Download: ML20024A696 (3)

Text

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REPQRT DATE 8 60 St DOCKET WMgER EVENT DESCRIPTION AND PROBA8LE CONSEQUENCES h to12l l On 5-16-83 during LES-MS-01 outboard Main Steam isolation Valve 1 B21-F028C Reactor l

, o , ., , g Protection System Trip Channel A2 limit switch failed to ope ate properly. Tech Spec. t 2.2.1 Allowable Value of equal to or less than 12% of MSIV closure was not met. A re- l l o 14 I I 1o 1s1 I dundant RPS Trip Channel A21imit switch on inboard MSIV 1B21-F022C was found within ]

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, , , o , l The 1Imi t swi tch actuating arm on 1B21-F028C falled to make proper contact wi th the gi limi t swi tch. The cause for the misalignment could not be determined. 'The limit i l

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1. LER NUMBER: 83-051/03L-0

11. LASALLE COUNTY STATION: Unit 1 Ill. DOCKET NUMBER: 050-373 IV. EVENT DESCRIPTION:

On May 16,1983 at 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />, during the performance of LES-MS-101, Main Steam isolation Valve Closure Cnannel Calibration, Outboard MSIV 1821-F028C Reactor Protection System Trip Channel A2 limit switch failed to operate p rope rly. Technical Specification 2.2.1 allowable, value of equal to or less than 12% of MSiv Closure was not met.

V. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

At the time of the survelliance the Reactor was in Condition 4, cold shutdown.

A redundant RPS Trip Channal A2 limit switch on inboard MSlV 1821-F022C was found within Tech. Spec. limits. This switch would have caused Reactor Auto-SCRAM Trip Logic B1 to initiate had a MSIV isolation occurred.

On 3/24/83 LOS-RP-M1, Main Steam isolation Valve SCRAM Functional Test had been performed satisfactorily. This test verified the operation of the -

RP Trip Channel A2 limit switch on 1821-F028C at that time.

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The health and safety of the public was preserved at all times.

VI. CAUSE:

The limit switch actuating arm on 1821-F028C failed to make proper contact with the limit switch. The cause for the misalignment could not be deter-mined.

Vll. CORRECTIVE ACTION:

The limit switch was readjusted to actuate at the Tech. Spec. Trip Setpoint of equal .to or less than 8% MSIV Closure per the LES-MS-101 procedure and

- Tech Spec Table 2.2.1-1 at 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on 5/16/83.

Prepared by: R. W. Houston

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Commonwealth Edison

(' e LaSilla County Nuclsar Station RuralRouta #1, Box 220 b'

(. Marseilles, Illinois 61341 qj } Telephone 815/357-6761 i

June 14, 1983 Mr. James G. Keppler Regional Administrator Region lli U.S. Nuclear Regulatory Commission 799 Roos.-vel t Road Glen Eliyn, IL 60137

Dear Si r:

Reportable Occurrence Report #83-051/03L-0 Docket #050-373 is being sub-mitted to your office in accordance with LaSalle County Nuclear Power Station Technical Speci fication 6.6.B.2. (a) . Reactor protection system or engineered safety feature instrument settings which are found to be less conservative than those established by the technical specifications but which do not pre-vent the fulfillment of the functional requirements of affected systems.

G. J. Diede ich Supe ri ntenden t LaSalle County Station GJD/GW/rg Enclosu re cc: Director of Inspection & Enforcement Di rector of Management In forma tion & P rogram Con t roi U.S. NRC Document Management Branch inpo-Records Center File /NRC JUN 1 6 1983 l

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