05000366/LER-1980-087-03, /03L-0:on 800528,during Surveillance Procedure HNP-2-3154,reactor Pressure Vessel Level Instrument (LPCI) Ft&C on 2B21-NO31B,Switch 4,had Double Actuation.Caused by Slipped Magnets on Pointer Shaft Due to Corrosion

/03L-0:on 800528,during Surveillance Procedure HNP-2-3154,reactor Pressure Vessel Level Instrument (LPCI) Ft&C on 2B21-NO31B,Switch 4,had Double Actuation.Caused by Slipped Magnets on Pointer Shaft Due to Corrosion

ML19318B005
Person / Time
Site:	Hatch
Issue date:	06/19/1980
From:	Nix R GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19318B003	List: 05000366/LER-1980-087, Forwards LER 80-087/03L-0 05000366/LER-1980-087-03, /03L-0:on 800528,during Surveillance Procedure HNP-2-3154,reactor Pressure Vessel Level Instrument (LPCI) Ft&C on 2B21-NO31B,Switch 4,had Double Actuation.Caused by Slipped Magnets on Pointer Shaft Due to Corrosion
References
LER-80-087-03L, NUDOCS 8006240514
Download: ML19318B005 (2)

LER-1980-087, /03L-0:on 800528,during Surveillance Procedure HNP-2-3154,reactor Pressure Vessel Level Instrument (LPCI) Ft&C on 2B21-NO31B,Switch 4,had Double Actuation.Caused by Slipped Magnets on Pointer Shaft Due to Corrosion

Event date:
Report date:
3661980087R03 - NRC Website

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h yl With the reactor in the run mode, while performinn Surveillance procedure l

llNP-2-3154, RPV Level Instrument (LPCI) FT&C on 2B21-NO31B, Switch No. 4 l

TT O I TTTl I had doubic actuation. It would pick-up at the proper decreasitig signal.

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but ns it decreased past the setpoint it would drop out again.

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lTTTlI shaft had slipped causing the switch to double actuate.

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ITT R 1 placed and the magnets were adjusted. Calibration was performed on the in-gl strument and llNP-2-3154, RPV Level Instrument (LPCI) FT&C was performed l

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- Reportabic Occurrence Report No. 50-366/1980-087.

With the reactor in the run mode, while performing Surveillance pt.cedure IINP-2-3154, RPV Level Instrument (LPCI) FT&C, on 2B21-NO31B, Switcl No. 4 4

had-doubic actuation. It would pick-up at the proper decreasing sigaal, but

as it~ decreased passed the setpoint it_would drop out again.

Switch No. 4

['

is the. low water level initiation for RCIC.

t This is a repetitive event as reported on Reportable Occurrence Report 50-366/

3 1979-082.. There was no effect upon public health or safety nor was aafe plant i

operation'affected.

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There were two reasons why the switch on the Yarway had double actuation.

First, the magnets on the pointer shaf t had slipped causing the high point of the magnet to pass by the Acro-switch assembly, thus causing the switch f-to drop out after it had picked up.

Second, the switch assembly had corrosion l

built up on it causing slow switch action.

r The magnets were adjusted, the switch assembly was replaced and calibration was performed per liNP-2-5281, Calibration procedure for Yarway Models 4118C, i

4118D and 4455 Level Indicators-Level Indicating Switches with Brooks Converter.

ilNP-2-3154, RPV Level Instrument (LPCI) FT&C, was performed with satisfactory results.

Unit I has the same level system, but IINP-1-3154 was performed to ensure the switches were operating correctly.

The results were satisfactory. The switches

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on Unit I and Unit II were inspected per Maintenance Requests, 1-80-2971 for Unit I and 2-80-2501 for Unit II. No other problems were found.

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