ML20064F722

/03L-0 on 781101:axial Flux Difference Deviated Greater than -5% from Target for One Minute.Caused by Pwr Reduction Necessitated by Problem with Cooling Fans on Main Station Transformer C

ML20064F722
Person / Time
Site:	North Anna
Issue date:	11/27/1978
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20064F721	List: ML20064F720 ML20064F722 ML20064F726 ML20064F733 ML20064F740
References
LER-78-114-03L, LER-78-114-3L, NUDOCS 7812040211
Download: ML20064F722 (2)

Text

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LICENSEE EVENT REPORT

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l@OW T iOl1l ZRN l60L l@l 0 l 5 l DOCK 0 l ET 0 NUMBER l0 l 3 l 3 l868 l@l1 11EVENT 10 OATE l1 17 1874 l@l75 11 REPORT 11 21 71 7{.J.T DATE 80 I H G1 63 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 10 I 2 l l During a power reduqtion, the axial flux difference deviated areater than-5% from the i 1

o ,3 i l target for one minute. This is in violation of T.S. 3.2.1. Since there was less thani 1

(n i4 i j one hour penalty accumulation, operation was allowed to continue as oer action statn- I oisi iment a.2 of T.S. 3.2.1.

This event is reportable as per T.S. 6.9.1.9.b. I l

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l i l O l lThe cause of the AFD Deviation was,a oower reductinn necessitated hv a nrnblom taith I Ii Ii I lthe cooling fans on the main station transformer "C" The rnar-tnr tea c trinped b_y tha l g q greactor operator as a result of the loss of cooling to the transformer, which ended I i ,i,i l surveillance requirements. No farther corrective action was required. l l1 l4l l l 1 8 9 80 ST S *. POW E R OTHE R STATUS 015 RY DISCOVERY DESCnIPTION 1 l 5 l [F_j@ l O l 8 l O l@l NA l lAl@l Operator Observation l

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER 78-114/03L-0 Description of Event ,

On 11-1-78, during a power reduction, the Axial Flux Difference deviated greater than -5% from target for a one minute duration. This is in violation of T.S. 3.2.1. Since there was less than one hour penalty accumulation, opera- ,

tion was allowed to continue as per Action Statement a.2 of T.S. 3.2.1. This event is reportable as per T.S. 6.9.1.9.b. .

t Probable Consequences of Occurrence Surveillance of the Axial Flux Difference assures that the limits of the heat flux hot channel factor are not exceeded during rormal operation or in the -

event of Xenon redistribution following power changes. This provides protection against exceeding the DNBR and peak fuel clad temperatures.

Since the AFD was returned to its limit within the time allotted, there was  !

no effect upon the safe operation of the plant. As a result, the peblic health  !

and safety was not endangered. '

Cause of Occurrence l The cause of AFD deviation was a power reduction necessitated by a problem' with the cooling fans of Main Station transformer "C". The automatic rod insertion forced the flux out of the target band.

Immediate Corrective Action The reactor was tripped by the reactor operator as a result of the loss of cooling to the transformer which ended the surveillance requirements.

c Scheduled Corrective Action No further corrective action required.

Actions Taken to Prevent Recurrence  ;

No further actions are required. -

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