ML20027D860

LER 82-066/03L-0:on 821008,during Instrument Calibr,Flux Penalty Input to Channel 1 Overtemp Delta T Setpoint Found Out of Tolerance.Cause Unknown.Channel Recalibr W/Satisfactory Results

ML20027D860
Person / Time
Site:	North Anna
Issue date:	11/03/1982
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20027D857	List: ML20027D856 ML20027D860
References
LER-82-066-03L-02, LER-82-66-3L-2, NUDOCS 8211100277
Download: ML20027D860 (4)

Text

, .

U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1) (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

/0/1/ /V/A/N/A/S/1/ (2) /0/0/-/0/0/0/0/0/-/0/0/ (3) /4/1/1/1/1/ (4) /// (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT 0/1/ R O R

/L/ (6) /0/5/0/0/0/3/3/8/ (7) /1/0/0/8/8/2/ (8) /1/1/3 /3 /8 /2 / (9)

DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

/0/2/ / On October 8, 1982, during a Unit I refueling outage, an instrument calibration /

/0/3/ / check showed that the flux penalty input to the Channel 1 overtemperature delta T/

/0/4/ / setpoint was out of tolerance. Channels II and III were correctly calibrated. /

/0/5/ / The Unit would be chutdown in the event delta flux reaches -50 percent and the /

/0/6/ / delta flux penalty for the overtemperature delta T setpoint was conservative for/

/0/7/ / delta flux values less negative than -50 percent. The public health and safety /

/0/8/ / were not affected. This event is reportable pursuant to T.S. 6.9.1.9.a. /

SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

/0/9/ /I/A/ (11) /E/ (12) /E/ (13) /I/N/S/T/R/U/ (14) /Y/ (15) /Z/ (16)

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

(17) REPORT NUMBER /8/2/ /-/ /0/6/6/ / 's / /0/3/ /L/ /-/ /0/

ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON Pl. ANT METHOD HOURS SUEMITTED FORM SUB. SUPPLIER MANUFACTURER

/E/ (18) /2/ (19) /Z/ (20) /Z/ (21) /0/0/0/0/ (22) /Y/ (23) /N/ (24) /N/ (25) /W/1/2/0/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

/1/0/ / The cause of the event is unknown. Channel drift is the suspected cause. The /

/1/1/ / channel was recalibrated with satisfactory results. /

/1/2/ / /

/1/3/ / /

/1/4/ / /

FACILITY METHOD OF STATUS  % POWER DISCOVERY DISCOVERY DESCRIPTION (32)

OTHER NA STATUS (

/1/5/ /H/ (28) /0/0/0/ (29) / / /B/ (31) / Technician Observation /

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35) LOCATION OF RELEASE (36)

/1/6/ /Z/ (33) /Z/ (34) / NA / / NA /

PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

/1/7/ /0/0/0/ (37) /Z/ (38) / NA /

PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ /0/0/0/ (40) / NA /

LOSS OF OR DAMAGE TO FACILITY TYPE DESCRIPTION 43)

/1/9/ /Z/ (42) / NA /

PUBLICITY ISSUED DESCRIPTION (45) NRC USE ONLY

/2/0/ /N/ (44) / NA /////////////

NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8211100277 821103 PDR ADOCK 05000330 S PDR

Virginia Electric and Power Company North Anna Power Station, Unit No. 1

Attachment:

Page 1 of 2 Docket No. 50-338 Report No. LER 82-066/03L-0 Description of Event On October 8, 1982, during a Unit I refueling outage, an instrument calibration check showed that the flux penalty input to the Channel I overtemperature delta T setpoint was out of tolerance. For delta flux values more negative than -50 percent, the delta flux penalty input to the overtemperature delta T setpoint was less than the penalty required by T.S. table 2.2-1. The attached graph displays both the desired and as found delta flux penalty functions. This event is reportable pursuant to T.S. 6.9.1.9.a.

Probable Consequences of Occurrence T.S. Table 2.2-1 requires that:

"for each percent that the magnitude of (q - qh) exceeds - 34 percent, the AT trip setpoint shall be automatically reduced by 3 percent of its value at RATED THERRAL POWER".

No maximum penalty or delta flux operating range for the penalty is specified by T.S. table 2.2-1.

The Westinghouse " Precautions, Limitations, and Setpoints" document for North Anna Power Station specified, prior to the current Unit 1 Tavg upgrade, that the " Cutoff" limit for the flux penalty must be greater than or equal to its value at +35 and -50 percent delta flux. The PLS

" Cutoff" limits are shown on the attacht.d graph.

The as found delta flux penalty was more conservative than the delta flux penalty required by the PLS. It appears that the as found delta flux penalty was more conservative than the penalty assumed in the safety analysis. The safety analysis is currently being checked for delta flux penalty assumptions.

The as found delta flux penalty was less conservative than the penalty specified in the Technical Specifications. The delta flux penalty function specified in the Technical Specifications is specified without bounds. Currently the delta flux penalty function is calibrated to increase as large as electronically practical. As shown on the attached graph the penalty is allowed to increase to 150 percent.

The disagreement between the as found delta flux overtemperature delta T penalty function and the penalty function specified in the Technical Specifications appears to have no safety implications. An investigation is being conducted to determine the delta flux penalty function " Cutoff" limits used in the safety analysis. If appropriate, a Technical Specification change request will be submitted to incorporate

" Cutoff" limits when the investigation is complete.

L

1 . . ,

Attachment:

Page 2 of 2 The Unit would be shutdown in the event ' delta flux reaches -50

. percent and the delta flux penalty for the overtemperature delta T setpoint was conservative for delta flux values less negative than -50 percent. Channels II and III : were correctly calibrated ' and provided required protection (2/3 logic). The public health and safety were not affected.

Cause of Event A review of past channel calibrations revealed no discrepancies which would have caused a shift in the delta flux overtemperature delta.

T setpoint penalty. A channel calibration performed on January 8, 1981 showed that the delta flux overtemperature delta T setpoint penalty was correct at that time. It appears that between - January 8, 1981 and October 8, 1982 that the Channel I delta flux overtemperature delta T penalty function generator card drifted.

Immediate Corrective Action The overtemperature delta T setpoint circuit was recalibrated with satisfactory results.

Scheduled Corrective Action No further action is required.

Actions Taken to Prevent Recurrence No further actions are required.

Generic Implications There are no generic implications associated with this event.

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