ML19210D302
| ML19210D302 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 11/20/1979 |
| From: | Taylor J BABCOCK & WILCOX CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7911260278 | |
| Download: ML19210D302 (2) | |
Text
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Babcock &Wilcox ee.er cenereocn c<cuo P.O. Bex 1260. Lynchburg, Va. 24505 Teleoncne: (804) 384-5111 November 20, 1979 Mr. Darrell G. Eisenhut Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
Cladding Swelling and Rupture Models for LOCA Analysis
Dear Mr. Eisenhut:
On November 14, 1979, Mr. R. P. Denise of the Division of Systems Safety contacted B&W with regard to the Burst Temperature Cutve approved for use by B&W in LOCA analyses.
Mr. Denise re-quesced B&W te co m ider the effect of employing the Staff's ramp rate correlation as contained in Draft NUREG 0630 to determine the Burst Temperature Curve for use in LOCA analyses.
B&W han examined the ramp heat up rates calculated prior to rupture for B&W NSS systems which have either OLs or cps granted under 10 CFR 50.46.
(Documented in BAW-10102, Rev. 2, BAW-10103A, Rev. 3, and BAW-10105, Rev. 1.)
Interpolating from the Staff's ramp heat up rate versus hoop stress and failure temperature referenced above, B&W has found that the Staff's correlation predicts the fuel cladding to rupture at the same or higher temperatures for all cases, except the 4-foot core elevation for the 177-Fuel Assembly raised-loop plant (BAW-10105, Rev. 1).
The ramp rate prior to rupture for this case is approximately 12 C/s, while the extrapolation of the NRC curves to the B&W Burst Temperature Curve at the same stress indicates a 22 C/s heat up rate. B&W has estimated that the effect would be an earlier rupture, and, tturefore, additional oxidation due to metal-water reaction, resulting in in increase of approximately 80*F in the peak cladding temperature (PCT).
The original analysis showed a peak cladding temperature of 2073*F.
The addition of SOF woold result in a peak of 2153*F and nor violate the requirements of 10 CFR 50.46.
Since the issuance of BAW-10105, Rev. 1, B&U has identified further con-servatisms which amount to a reduction in peak cladding tempera-ture of approximately 30*F.
Therefore, if the evaluation were 1390 164 s co3 s
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Babcock & Wilcox Mr. Darrell Eisenhut November 20, 1979 to include these further conservatisms, and the NRC ramp rate correla-tions employed, we would expect a peak cladding temperature increase of about 50*F (2123*F peak) with no difficulty in demonstrating com-pliance to 10 CFR 50.46.
In summary, B&W has examined the effect of the use of the Staff's ramp rate correlation as requected and found the calculated PCT to be either unchanged or lowered as a result except for the one case noted above.
If there are any qt.estions concerning this response, please call me or Henry Bailey (Ext. 2678) of my staff.
Very truly yours,f, 7
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James H. Taylor Manager, Licensing JHT/lc 1300 165