05000339/LER-1980-068-03, /03L-0:on 801004,summing Amp Card Was Discovered Out of Cal.Caused by Procedural Inadequacy Resulting in Undetected Setpoint Drift.Summing Amps Recalibr

/03L-0:on 801004,summing Amp Card Was Discovered Out of Cal.Caused by Procedural Inadequacy Resulting in Undetected Setpoint Drift.Summing Amps Recalibr

ML19339B961
Person / Time
Site:	North Anna
Issue date:	11/03/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19339B958	List: 05000339/LER-1980-068, Forwards LER 80-068/03L-0 05000339/LER-1980-068-03, /03L-0:on 801004,summing Amp Card Was Discovered Out of Cal.Caused by Procedural Inadequacy Resulting in Undetected Setpoint Drift.Summing Amps Recalibr
References
LER-80-068-03L-02, LER-80-68-3L-2, NUDOCS 8011100498
Download: ML19339B961 (3)

LER-1980-068, /03L-0:on 801004,summing Amp Card Was Discovered Out of Cal.Caused by Procedural Inadequacy Resulting in Undetected Setpoint Drift.Summing Amps Recalibr

Event date:
Report date:
3391980068R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION 9

LICENSEE EVENT REPORT CON'iROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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

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/4/1/1/1/1 (4)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT E g/ (6)

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(7)

/1/0/0/4/8/0/ (8) /1/1/0/3/8/0/_(9)

DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUEN"ES (10)

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While recalibrating high steam flow setpoint summing amp cards nn Octc ber 4,

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1980, instrument technicians discovered that a summing amp card was non-

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conservatively out of calibration. This event is reportable pursuant to T.S

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6.9.1.9.c.

Since the safety analysis of the steam line break accident is

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relatively insensitive to the High Steam Line Flow SI actuation setting and

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two other signals for SI actuation in response to a steam line break accident /

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were available, the public health and safety were not affected.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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/I/B/ (11) /D/ (12) /Z/ (13) /I/N/S/T/R/U/ (14) /_Q/ (15) g/ (16) l SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REF3RT NO.

CODE TYPE NO.

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1 ACTION FUTUr.E EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP.

COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUw!ITTED FORM SUB. SUPPLIER MANUFACTURER

/E/ (18) $/ (19) /Z/ (20) /Z/ (21) /0/0/0/0/ (22) LY/ (23) /N/ (24) /N/ (25) /W/1/2/0/ (26 CAUSE Dr.SCRIPTION AND CORRECTIVE ACTIONS (27)

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The cause of the event was a procedural inadequacy which allowed the setpoint /

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drift to go undetected.

The summing amps were recalibrated. No further

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corrective actions are required.

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FACILITY METHOD OF STATUS

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NA LB/ (31)

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ROUTINE TEST

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j ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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PERSONNEL INJURIES NUMBER DESCRIPTION (41)

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LOSS OF OR DAMAGE TO FACILITY (' )

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PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

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NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8011100-197

Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 2 Docket No. 50-339 Report No. LER 80-068/03L-0

Description of Event

Steam flows for each steam generator are obtained by measuring the pressure differential between the throat of a venturi tube and a point upstream of the venturi tube. Full scale differential pressure indication (100% Delta P) corresponds to 1687.4 inches of water and 5 million lb/hr (123.8% full load flow). The Technical Specification specify a high flow trip setpoint Delta P corresponding to 40% of full steam flow between 0 and 20% turbine load and then a Delta P increasing linearly to a Delta P corresponding to 110% of full steam flow at full turbine load.

The allowable setpoint values are less than or equal to a Delta P corre-sponding to 44% of full steam flow between 0 and 20% turbine load and then a Delta P increasing linearly to a Delta P corresponding to 111.5%

of full steam flow at full turbine load.

On October 2, 1980, Westinghouse notified Vepco that the Delta P i

setpoints specified in the PLS Document were in error and were not in agreement with the setpoints specified in the Technical Specifications (This event was reported in Unit 1 LER 80-084/01T-0). New Delta P setpoints consistent with T.S. requirements were calculated and instru-i mentation technicians were instructed to recalibrate appropriate summing amp cards. While recalibrating the summing amp cards on October 4, 1980, the instrument technicians discovered that a summing amp card was i

out of calibration in the nonconservative direction when compared to the Delta P setpoint originally specified in the PLS Document and the calibra-tion procedure. The worst case error is given below:

SETPOINT (% FULL LOAD STEAM FLOW)

TURBINE AS ORIGINAL CORRECT ALLOWABLE LOAD (%)

FOUND PLS plLUE LIMIT l

80 108.5 105.8 98.8 100.5 This eventLis reportable pursuant to T.S. 6.9.1.9.c.

Probable Consequences of Occurrence The noncanservative setpoint reduced the safety margin for a SI signal. generated by a high steam line flow coincident with low steam line pressure or Lo-Lo Tavg. Protection against a steam line break accident was reduced. Two other SI signals for steam line break protection were available; pressurizer low pressure and high differential pressure between steam lines. Since the safety analysis of the steam line break accident is relatively insensitive to the High Steam Line Flow SI actuation setting and two other safety signals for SI actuation in response to a steam line break accident were available, the pubite health and safety j

were not affected.

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Attachment: Page 2 of 2

Cause of Event

The cause of the event was a procedural error which allowed the setpoint drift to go undetected. The input signal specified was such that the output of the summing card was limited by the output limiting i

feature of the card. This allowed the non-conservative drift to go undetected.

Immediate Corrective Action

i The summing amps were recalibrated.

i Scheduled, Corrective Action The procedures will be corrected prior to their next use.

Actions Taken to Prevent Escurrence No actions to prevent recurrance are required.

i Generic Implications-This error is also applicable to Unit 1.

Procedares for Unit I will also be corrected. Unit I setpoints have been verified to be within the specified limit.

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