ML19345C500

Responds to NRC 801105 Ltr Requesting Addl Info Re Effect of Split Breaks on Peak Clad Temp.Forwards Analysis of Results of double-ended Cold Leg Break

ML19345C500
Person / Time
Site:	McGuire, Mcguire
Issue date:	12/02/1980
From:	Parker W DUKE POWER CO.
To:	Harold Denton, Youngblood B Office of Nuclear Reactor Regulation
References
NUDOCS 8012050391
Download: ML19345C500 (3)

Text

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l DUKE POWER COMPANY l

Powra Butz.ntxo 422 SOUTH CHUaCH SrazzT. CnAnt.orrt, N. C. 28242 4

2 w".um o. **a a r a. s a. December 2, 1980 wer Persioc=v tr.ce=o=c: Anta 704 Seta= Peoouction 373-4c s 3 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatcry Commission

, Washington, D. C. 20555

, Attention: Mr. B. J. Youngblood, Chief Licensing Projects Branch No. 1 Re: McGuire Nuclear Station Docket Nos. 50-369, 50-370

Dear Mr. Denton:

Mr. R. L. Tedesco's letter of November 5, 1980 requested additional information concerning the effect of split breaks on peak clad temperature. The attached analysis results for a double-ended cold leg split break with a Cd = .6 (imperfect mixing) confirm that split breaks are not limiting for McGuire.

If there are further questions regarding this matter, please advise. This attached information will be included in the next revision to the McGuire Final Safety Analysis Report.

Very truly yours, O  % 0 0F 1 ,i.

William O. Parker, Jr.

GAC: tes Attachment 3o0/.s i

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MCGUIRE NUCLEAR STATION-Response to Mr. R. L. Tedesco's Letter of November 5, 1980 '

A Cd = 0.6 DECL split break LOCA has been analyzed for McGuire using the approved UHI Evaluation Model with imperfect mixing assumed in the vessel upper head. Results obtained based on 3411 MWt core power and Fq = 2.32 are ,

summarized in the tables below: '

Time Sequence of' Events (seconds):

Start 0.0

) Reactor Trip Signal 1.2

! UHI Accumul/cor Injection 2.1 i

Cold Leg Accumulator 16.2

- Injection UHI Accumulator Injection 22.0 Complete Pumped Injection 26.2 End of Bypass 60.8 Bottom of Core Recovery _ 85.5 Cold. Leg Accumulator Empty 114.6

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Clad Heatup Results:

Peak Clad Temperature (OF) 1800.0 Peak Clad Temperature 7.5 4 Loca tion (f t)

Local Zr/H 90 Reaction 2.1-(max) (%) ~

l Local Zr/H2O Location, - (f t) 7.5 Total Zr/H O 2 Reaction, (%) <0.3 Hot Rod Burst Time, (.sec) 89.8 Hot. Rod Burst Location, (ft) 5.5 1

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. The calculate'd peak clad temperature (PCT) is much less- than the 2140F value computed for the limiting case break (Cd = 0.6 DECLG, perfect mixing) for McGuire. In addition, perfect mixing split cases have previously demonstrated a low calculated PCT. Therefore, it is clear that no split break case will be limiting for McGUire or any other-UHI plant of similar design.

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