ML19210D687

LER 79-143/01T-0:on 791109,fuel Vendor Identified Potential Problem Affecting Temp of Large Break LOCA-ECCS Evaluation Model.Caused by Erroneous Fuel Burst Calculations.Study in Progress for Peak Clad Temp

ML19210D687
Person / Time
Site:	North Anna
Issue date:	11/21/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19210D670	List: ML19210D668 ML19210D677 ML19210D687
References
LER-79-143-01T, LER-79-143-1T, NUDOCS 7911270451
Download: ML19210D687 (2)

Text

NRC FORM 366 . .

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LICENSEE EVENT REPORT (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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DATE tIO 7 8 60 63 DOCKET NUMBER EVENT D ATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l VePeo was notified by the fuel vendor th.-t a potenti31 noncnnsoruntion fn 2 t., rg g

o ;3 ; g its large break LOCA-ECCS Evaluation Model exists. This problem could nFfore tho no g te 1 o 4 l clad temperature calculated for the large break LOCA-ECCS transiont - N kn,1 t k_ yd I o s l safety of the general public were not af fected. Reportable pursuant en T A 6c 1 RkI 10161l I I

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9 10 11 12 13 18 19 20 SEQUENTI AL OCCURRENCE REPORT REVISION EVENTYEAR REPORT NO. CODE TYPE N O.

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JJ 34 35 36 31 40 41 42 43 44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i o l The problem is related to fuel burst calculations and the use of notentin11y nnnennenrJ

i ;i i vative clad heatup rates. Reanalysis for the LOCA-ECCS neak clnd t onn o r, tii vo , , q ,, g I

, g a more recent evaluation model is in progress. I I

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PERSONNEL EXPOSURES NU ER TYPE DESCRIPTION FiTTl 1 0 0l@lZl@l l PERSONNE L INJURIES NU 9ER DESCRIPTION h I i R 10 l01@l12 7 8 9 11 l1 Q " 80 LOSS OF OR DAMAGE TO FACILITY 43 D E SC Rip TION ./ / v UU TYPE i 9 l Z gl NA l 80 7 8 9 10 2 o ISSUEf@

LN_ l NADESCRIPTION l lllllllllllllg 7 8 9 to 68 69 80 5 NAME OF PREPARER ", ", 1 -;;righ; P g_g

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

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER/R0 79-143/01T-0 Description of the Event The fuel vendor notified Vepco on November 9,1979 that a potential nonconser-vative feature of its large break LOCA-ECCS evaluation model existed. This event is reportable pursuant to T.S. 6.9.1.8.h.

Probable Conseque~nces of the ' Event This problem could affect the peak clad temperature calculated for the large break LOCA transient. The F(Q) limit may be affected. The health and safety of the general public were not affected by this event.

Cause This new discovery resulted from work performed subsequent to meetings held with the NRC on November 1 and 2,1979 concerning studies made by Oak Ridge National Laboratory. The fuel vendor determined that a nonconservative fea-ture could exist in the large break LOCA-ECCS analysis with respect to the portion of the calculation related to fuel rod burst. The existing fuel rod burst model used clad heatup rates of 25 F per second or greater. Actually, clad heatup rates could be less than the existing model. A shift in clad burst time can affect the peak clad temperature calculated for the LOCA transi-ent.

Immediate Corrective Action Discussions were held with the fuel vendor with respect to reanalysis of the LOCA transient to formulate scheduled corrective actions.

Scheduled Corrective Action It is anticipated that the required analysis will be completed in December 1979 and the F (Q) limit modified, if required.

Actions Taken to Prevent Recscrence Not applicable to this event. .

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