ML20085G843

AO BFAO-50-259/7455W:on 741031,max Linear Heat Generation Rate Calculated Higher than Allowable Limit.Caused by Inadequate Margin Allowed in Max Linear Heat Generation Before TIP Set

ML20085G843
Person / Time
Site:	Browns Ferry
Issue date:	11/07/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G846	List: ML20085G843 ML20085G848
References
NUDOCS 8308290437
Download: ML20085G843 (2)

Text

r AETORIML OCCURRE: ICE REPORT Report Ilo.: EFAO-50-259/7455W Report Date: Itovember 7,1974 Occurrence Date: October 31, 1974 Facility: Browns Ferr/ Isuelcar Plant unit 1 Identification of Occurrence i Thenoximumlinearheatgenerationrate(MGR)wascalculatedtobe18.43kW/ft as co= pared to the 14"4t of 18.36 kW/ft.

Conditions Prior to Occurrence Tne reactor had been operating at 97-percent thermal power since october 23, 1974 There had been no recent rod movements or recirculation flow changes and core renon was at equilibrium. Eight hundred thirteen EFFH had elapsed since the previous full set of TIP's on August 31, 1974.

Description of Occurrence Two TIP sets are required to calibrate the LPRM's: one before calibration to determine the LPRM Cain adjustment factor and one after calibration to update the nuclear pregrc=. After the second TIP set van run, the maxirn: LEGR exceeded the specified limit. Calculations were ir.=ediately confirIned, and rceirculation flow was reduccd to bring the LHGR within linits.

Desir nation of Antarent Cause of Occurrence The variation between the first and second TIP set, which was run within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, was 1,6 percent. Variation between previous back-to-back TIP sets has been ruch less and only 0.5 percent between these sets end sets run 2' months ago. The large c=ount of variation was unexpected; and, as a result, adequate cargin was not allowed in the "ri-mm LEGR before the TIP set. ~

Analysis of Occurrence

- Technical specification 3.5.J. assures that the mGR in any rod is less than the design LEGR even if fuel pellet densification is postulated. The LEGR limit provides

. sufficient margin between the steady-state operating condition and any fuel damage condition to acco==odate uncertainties and to assure that no fuel damage results even during the worst anticipated transient condition at any time. Since the local exposurewaslessthan6,000 IGD /T,itcanbeseenfromthediscussioninFSAR Section 3.7.4.2. that fuel damage would not have been expected if the worst anticipated trcnsient had occurred. There were no adverse effects to the public health and safety as a result of this occurrence.

Corrective At tion The technical supervisor will review this event with the technical engineering group stressing'.the need to maintain sufficient margin to core operating limits.

Failure Data. <

8308290437 741107 Not applicable.

[DRADOCK 05000259 PDR

- . . - - - - - _-_:---__---_ - _ _ - - - - - - - _ -- - - _ _ . - - - - M

._.---

• c-l

• l'iE N b! E 3 S !E '.2 ' /.M.' 9 'T F: C 71.'r r ~ -

• C H AY'e ."u'E :.3 Gi>((TiO'd N E2 . , - : E ; '.

l37G01 i

\

', s <

~ ' ' (N L:. ,,;

+ . - /,n\

s nnw v as it

. .y

. iy

} \, PA Fll . , f il' >

aim er 7, I??L .v 9 ,J ,, , A ,.

J gf p, -.

4, c [.; vL-k_', I 4

ei s4 _s

>> (

y l~v l ~

e. 7 y

C. r %. .i s Fr. Edcon G. Cace  :- A / '

Acting Director of Licen::inc Office of EcGulation .'l,fI W 'i j/',\)'.._..<'.t U.S. Ister.lic Energy Ccciiccion Vachington, DC E0545

Dear Mr. Case:

TEil!ESSEE VALLEY AUrdORITI - BRO',lHS FERRY ITUCLEAR PL/Mf U'iIT 1 -

DOCKET HO. 50-259 - FACILITI OPERATING LICZCE DPR AE30R!:AL OCCURRZiCEREPORIBFAO-50-259/745517 The enclocci report is to provide details concerning the naninu: 1 linear heat Generation rate (LEGR) which vac calculated to be 18.43 k',1/ft as ccacred to the li:ait of 18.36 Ifd/ft end is cub: itted in accordance with Appendin A to Restlatory Guide 1.16, Revision 1, October 1973. This event occurred on Brounc Ferr' / Iinclear Plent unit 1 on October 31, 1974 Vor/ tru3,y yourc, TECTESSEE VIT.TEI AUrdORITI

/ '

l-E. F. Thonac

,?

Director of Power Production Enclocure CC (lhelocure): m l'r. I!om2 C. Focelcy, Director Region II Reculatorf Operationc Office, USAEC 230 Peachtree Street,137. , Suite 818 Atlanta, Georcia 30303 l

1 .1.Cv .j ')

.u .,.

a fs COPY SENT REGION

_ n ft