05000010/LER-1977-042-03, /03L-0:on 771031,scram Discharge Level Switch LS 264 Failed to Operate on Intial Quarterly Surveillance Dis 300-1 Test,But Did Operate on Subsequent Tests.Cause Not Determined.Safety Sys a Tripped & LS 264 Retested

/03L-0:on 771031,scram Discharge Level Switch LS 264 Failed to Operate on Intial Quarterly Surveillance Dis 300-1 Test,But Did Operate on Subsequent Tests.Cause Not Determined.Safety Sys a Tripped & LS 264 Retested

ML19338E413
Person / Time
Site:	Dresden
Issue date:	11/22/1977
From:	Lindberg C COMMONWEALTH EDISON CO.
To:
Shared Package
ML19338E412	List: 05000010/LER-1977-042, Forwards LER 77-042/03L-0 05000010/LER-1977-042-03, /03L-0:on 771031,scram Discharge Level Switch LS 264 Failed to Operate on Intial Quarterly Surveillance Dis 300-1 Test,But Did Operate on Subsequent Tests.Cause Not Determined.Safety Sys a Tripped & LS 264 Retested
References
LER-77-042-03L, LER-77-42-3L, NUDOCS 8009290535
Download: ML19338E413 (3)

LER-1977-042, /03L-0:on 771031,scram Discharge Level Switch LS 264 Failed to Operate on Intial Quarterly Surveillance Dis 300-1 Test,But Did Operate on Subsequent Tests.Cause Not Determined.Safety Sys a Tripped & LS 264 Retested

Event date:
Report date:
0101977042R03 - NRC Website

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8 60 61 DOCKET NUMBER 68 69 EVENT D ATE 74 S

REPORT DATE 60 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h 1o4:!.!During routine quarterly surveillance DIS 300-1, scram discharce level switch LS 264 I g o ;3l l failed to operate on the initial test but did operate on subsequent tests.

T.S. tab 1d Io i4 } !3.1.1.c requires two operable channels while in the run mode.

Remaininn 3 level swi-I

[ O l s i l tches in system were operable. Therefore, this event had no safety significance. This I lo is l lis the first occurrence of this nature on this system.

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I l,;7; l As 4 precautionary measure air gap between slug and magnet was reduced slichtiv and l

93 ;3gl switch is scheduled for two additional tests during the month of November.

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ATTACHMENT TO LICENSEE EVENT REPORT 77-042/03L-0 COMMOL'EALTH EDISON COMPANY (CWE)

DRESDEN UNIT 1 (ILDRS-1)

DOCKET # 050-010 During routine quarterly surveillance DIS 300-1 of the scram discharge level scram system, level switch LS 264 failed to operate on the initial test but did operate on several subsequent tests.

The scram discharge volume scram zystem consists of four float type level switches which are hard piped to the side of the discharge volume tank.

The switches are electrically connected in a "one out of two twice" logic array.

The "A" safety system was tripped, and LS 264 was retested.

The switch operated numerous times without failure and with no corrective action being taken.

As a precautionary measure, the air gap between the slug and magnet was reduced slightly and the switch was scheduled for additional testing dur-ing the next month.

The exact cause of this event is unknown at this time.

At the time of the occurrence the remaining three level switches in the system operated properly, therefore, this event had no safety significance.

The switch is a Magnetrol Model Number 751.

This is the first occur-rence of this nature on this system.

The float on LS 264 was recently re-placed, but the switch operated properly during post repair testing and during subsequent surveillances.

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1 u.s. NUCLE AR REtWLAT@GY COMP il%N DOCKET NUMBE R i NRC poru 195

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i yo jo NRC DISTRIBUTION con PART 50 DOCKET MATERIAL INCTt0ENT REPORT FROM:

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l Commonwealth Edison Company 11/22/77 Mr. James G. Keppler Morris, 111.

cats,sCsivee B. B. Stephenson 12/08/77 fusT+

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- OE SCRIPTICN ENCLCsVRE Licensee Event P port (R0 50-010/77-01?.03L-

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feature instrument settings found to be less conservative than those established by tech specs.....

i PLANT NAME: Dresden Unit No.1 RJL 12/09/77 (1-P)

( 1-P )+( 1-P )

NOTE: IF PERSONNEL EXPOSL"itE IS INVOLVED

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SEND DIRECTLY TO KREGER/J. COLLINS i

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