05000339/LER-1981-014-03, /03L-0:on 810122,spike Occurred on Channel 4,N-44, Giving 2/4 Coincidence Resulting in Inadvertent Reactor Trip.Cause Unknown.Prior to startup,N-44 Calibr Successfully.Recorders Have Shown No Abnormal Indications

/03L-0:on 810122,spike Occurred on Channel 4,N-44, Giving 2/4 Coincidence Resulting in Inadvertent Reactor Trip.Cause Unknown.Prior to startup,N-44 Calibr Successfully.Recorders Have Shown No Abnormal Indications

ML19343C086
Person / Time
Site:	North Anna
Issue date:	02/11/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19343C062	List: 05000339/LER-1981-014, Forwards LER 81-014/03L-0 05000339/LER-1981-014-03, /03L-0:on 810122,spike Occurred on Channel 4,N-44, Giving 2/4 Coincidence Resulting in Inadvertent Reactor Trip.Cause Unknown.Prior to startup,N-44 Calibr Successfully.Recorders Have Shown No Abnormal Indications
References
LER-81-014-03L, LER-81-14-3L, NUDOCS 8102180575
Download: ML19343C086 (2)

LER-1981-014, /03L-0:on 810122,spike Occurred on Channel 4,N-44, Giving 2/4 Coincidence Resulting in Inadvertent Reactor Trip.Cause Unknown.Prior to startup,N-44 Calibr Successfully.Recorders Have Shown No Abnormal Indications

Event date:
Report date:
3391981014R03 - NRC Website

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.6 U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT O

CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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/V/A/N/A/S/2/ (2)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

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REP 0RI [L/ (6)

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(8) /0/2/1/1/8/1/ (9) gp E DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On January 22,.1981, with the unit at 100% power, while power range channel 3, /

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N-43, was being tested and in the trip mode, a spike occurred on channel 4,

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N-44, which gave 2/4 coincidence resulting in an inadvertant reactor trip.

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Since the plant was safely shutdown the health and safety of the general public/

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were not affected. This is contrary to T.S. 3.3.1.1 since the minimum

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number of operating channels were less than 3, and reportable pursuant to

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T.S. 6.9.1.9.b.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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/I/A/ (11) [E/ (12) [E/ (13) /I/N/S/T/R/U/ (14) /P/ (15)

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SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO.

CODE TYPE NO.

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER [E/ (18) [X/ (19) [A/ (20) [C/ (21) /0/0/0/3/ (22) [Y/ (23) [N/ (24) [N/ (25) /W/1/2/0/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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The cause of the spike on N-44 is unknown at this time.

Prior to starting up /

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the unit, N-44 was calibrated successfully. Subsequent to the startup surveil-/

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lance tests were performed on all of the power range flux channels and N-44 was/

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again calibrated. Recorders monitoring these channels are reviewed daily and /

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no abnormal indications have been found.

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FACILITY METHOD OF STATUS

% POWER OTHER STATUS DISCOVERY DESCRIPTION (32)

/ (30) DISCOVERY

/1/5/

/E/ (28)

/1/0/0/ (29) /

NA [A/ (31)

/ OPERATOR OBSERVATION /

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)-

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NA

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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NA

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PERSONNEL INJURIES NUMBER DESCRIPTION (41)

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LOSS OF OR DAMAGE TO FACILITY ( 3)

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DESCRIPTION

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PUBLICITY ISSUED DESCRIPTION (45)

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NRC USE ONLY

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NAME OF PREPARER W. R.'CARTWRIGHT PHONE (703) 894-5151 8102180175' '

Virginia Electric and Power Company Attachment: Page 1 of 1 North Anna Power Station, Unit #2 Docket No. 50-339 Report No. LER 80-014/03L-0

Description of Event

On January 22, 1981, with the unit at 100% power, an inadvertant reactor trip resulted when a spike occurred on power range neutron flux indication channel 4, N-44, with channel 3, N-43, in the trip position.

This is contrary to T.S. 3.3.1.1 since the minimam number of operating channels were less than 3 and reportable pursuant to T.S. 6.9.1.9.b.

Probable Consequences of Occurrence Since the plant was immediately shutdown and maintained in mode 3, the health and safety of the general public were not affected.

Cause of Event

The'cause of the spike on channel 4, N-44, is unknown at this time.

Immediate Corrective Action

After the reactor trip, N-44 was calibrated prior to starting up and no descrepancies were found. Subsequently, al'. four power range neutron flux channels were calibrated and found to be operating correctly.

The recorders monitoring power range flux are being monitored for inconsistancy in indication. This prob:.em has not been observed during the past history of this plant.

Scheduled Corrective Actic_n Surveillance testing shall be performed on the nuclear instrumentation as required.

Action Taken to Prevent Recurrence The flux recorder are monitored daily for abnormal indication or spurious signals.

Generic Implications l

There are no generic implications associated with this event.

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