05000318/LER-1981-001-03, /03L-0:on 810107,Channel B Reactor Protective Sys Trip Units for High Power,Thermal Margin/Low Pressure & Axial Flux Offset Bypassed for Troubleshooting Linear Power Range Instrument.Detector Output Faulty

/03L-0:on 810107,Channel B Reactor Protective Sys Trip Units for High Power,Thermal Margin/Low Pressure & Axial Flux Offset Bypassed for Troubleshooting Linear Power Range Instrument.Detector Output Faulty

ML20003B193
Person / Time
Site:	Calvert Cliffs
Issue date:	02/05/1981
From:	Lagiewski J, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20003B187	List: 05000318/LER-1981-001, Forwards LER 81-001/03L-0 05000318/LER-1981-001-03, /03L-0:on 810107,Channel B Reactor Protective Sys Trip Units for High Power,Thermal Margin/Low Pressure & Axial Flux Offset Bypassed for Troubleshooting Linear Power Range Instrument.Detector Output Faulty
References
LER-81-001-03L, LER-81-1-3L, NUDOCS 8102100502
Download: ML20003B193 (2)

LER-1981-001, /03L-0:on 810107,Channel B Reactor Protective Sys Trip Units for High Power,Thermal Margin/Low Pressure & Axial Flux Offset Bypassed for Troubleshooting Linear Power Range Instrument.Detector Output Faulty

Event date:
Report date:
3181981001R03 - NRC Website

text

NT.C FORM 366 U.S. NUCLEAR HEGULATORY COMMISSION (7 77)

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4 60 61 oOCKeT NUV8eR 68 69 event oAre 74 75 RePoRr oATe 80 EVENT DESCRIPTION AND PROBA8LE CONSEQUENCES h 1o: 21 l At 0930, Channel 8 reactor protective system trip units for Hi Power, l

io i3 i l Themal Margin / Low Pressure (TM/LP) and Axial Flux Offset (AFO) wtre l

lo i Ai i bypassed for troubleshooting the linear power range instrument. The l

lo isi i detector output was faulty therefore Channel B Hi Power, TM/LP, and l

io is i l AFO trip units were placed in the tripped condition at 1255 on 1-8-81 l

lo17; I per T.S. 3.3.1.1.

The three redundant channels were operable. LER's 1

o ni i i 79-50 and 80-05 (U-2) report earlier symptoms of the problem.

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3J 34 35 36 37 40 el 42 43 44 47 CAUSE oESCRIPTION AND CORRECTIVE ACTIONS h Ii io i l The upper subchannel detector's field cable connector (King Electronics I

ml Co., Inc. #KH5905) was found loosened, makino intemittent contact. The I

i,i2i l connector will be replaced during the current refueling outage. This has I

L.' L2J l not been a repetitive failure; it is considered to be due to wear and I

iiiAi I handling during its service. No preventive acticr. is necessary.

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LER NO.

81-01/3L DOCKET NO.

50-318 LICENSE N0. OPR-69 EVEN1 DATE 01-07-81 REPORT DATE 02-05-81 ATTACHMENT CAUSE DESCRIPTION AND CORRELTIVE ACTIONS (CONT'D)

Operations personnel reportec a high deviation between the Channel "B" Ex-core Nuclear Instrument calculated ASI and the In-core calculated ASI. Subsequent attempts at calibration and troubleshooting revealed a further degeneration of the upper subchannel detector signal pre-viously reported on LER's 05000318/79-50 and 05000318/80-05. Oscillo-scope checks revealed regular noise spikes at this time, vice the sin-usoidal patterns detected in earlier troubleshooting.

In this and in earlier attempts at troubleshooting, connector cleaning and insulation resistance checks on the cable were included. Results were in expected ranges. After reactor shutdown for the current re-fueling and during preparations for the detector (2-NE-006) replacement, the faulted connector was noted. During the Unit 2 Refueling Outage, all sin Tar Ex-core Nuclear Instrumentation connectors have been sight verifieu as part of an engineering review in progress. Routine refueling surveillance tests of detectors and cables have disclosed no additional problems in cables or connectors. The connector will be replacea during the current refueling outage. Therefore, no preventive action is deemed necessary.