05000254/LER-1981-008-03, /03L-0:on 810407,reactor Core Insulation Cooling Sys Received Spurious High Steam Flow Automatic Isolation Signal.Caused by Faulty Micro Switch in DPIS 1-1360-1B. Switch Replaced & Instrument Calibr

/03L-0:on 810407,reactor Core Insulation Cooling Sys Received Spurious High Steam Flow Automatic Isolation Signal.Caused by Faulty Micro Switch in DPIS 1-1360-1B. Switch Replaced & Instrument Calibr

ML20003H956
Person / Time
Site:	Quad Cities
Issue date:	04/13/1981
From:	Weinfurter E COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20003H952	List: 05000254/LER-1981-008, Forwards LER 81-008/03L-0 05000254/LER-1981-008-03, /03L-0:on 810407,reactor Core Insulation Cooling Sys Received Spurious High Steam Flow Automatic Isolation Signal.Caused by Faulty Micro Switch in DPIS 1-1360-1B. Switch Replaced & Instrument Calibr
References
LER-81-008-03L-02, LER-81-8-3L-2, NUDOCS 8105080234
Download: ML20003H956 (2)

LER-1981-008, /03L-0:on 810407,reactor Core Insulation Cooling Sys Received Spurious High Steam Flow Automatic Isolation Signal.Caused by Faulty Micro Switch in DPIS 1-1360-1B. Switch Replaced & Instrument Calibr

Event date:
Report date:
2541981008R03 - NRC Website

text

U.S. NUCLEAR R3BU'MN NRC FCRM 366 (1773 LICENSEE EVENT REPORT CONTROL BLOCr* l l

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(PLEASE PRINT OR TYPE ALL REQUIRED INFOIMATis.}

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8 EVENT DESCRIPTION AND PROSABLE CONSEQUENCES h l 19 # 21 l At 11:40 a.m. the RCIC System received a spurious High Steam Flow automatic l

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isolation signal which closed valves M0-1-1301-16 and M0-1-1301-17 DTDl RCIC to be declared inoperable. The consequences are minimized by the fact that

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g3g,gl HPCI was available at all times per Technical Specification 3 5.E.2. and that RCIC l

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l lMg,J l The sourious sianal was caused by a faulty micro switch in DPIS 1-1960-1B which is l

I one of two bellows type pressure cells provided for this isolation function.

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50 p.m. on April 7, 1981.

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!.ER MUMBER: LER/R0 81-8/03L-0 11.

LICENSEE NAME: Commonwealth Edison Company Quad-Ci ties Nuclear Power Station 2

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FACILITY NAME: Unit One IV.

DOCKET NUMBER: 050-254 V.

EVENT DESCRIPTION

On April 7,1981 at 11:40 a.m., while Unit One was in RUN mode at 806 MWe and 2481 MWt, Reactor Core Isolation Cooling System (RCIC) Automatic-Isolation and RCIC High Steam Flow signals were received by the unit operator. The RCIC Automatic isolation closed valves M0-1-1301-16 and MO-1-1301-17, thereby. isolating the steam supply to the RCIC turbine. The RCIC system was declared inoperable. Technical Specification 3 5.E.I.

requires the RCIC system to be operable whenever reactor pressure is greater than 150 psi. A similar. event occurred in 1979 (LER/R0 79-01/

03L-0) when Unit Oae RCIC Automatic isolation tripped on a high steam flow signal.

In accordance with Technical Specification 3 5.E.2.,

preparations were made to demonstrate the operability of the HIqh Pressure Coolant injection System (HPCI).

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The er

'quenc.es of this occurrence are minimized due to the short outage of ti system (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 10 minutes), and because safe plant operation was m.

' with the HPCI system being available. The RCIC High Steam Flow iso,

, designed to isolate the RCIC steam line in case of a RCIC pipe bi..

outside of the ?ramary Containment. This feature functioned os designed.

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CAUSE

The spurious High Steam Flow signal was due to a micro switch in.one of two differential pressure cells, DPIS-1-1360-1B which failed in the CLOSED position. This is a Bellows type pressure cell, manufactured by Barton

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instruments Company, Model Number 288.

l Vill. CORRECTIVE ACTION:

Immediate action was to initiate demonstration of operability of the H?Cl System. Work Request Q11969 was issued to replace the low side micro switch and recalibrate according to QlS 18-1, RCIC Steam Line High Flow Calibration. The switch was replaced and set at 200" H 0; normal setpoint 2

ls 200" + 4" H20. The RCIC Automatic isolation was cleared and 'the system was declared operable at 1350 on April 7, 1981.

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