ML19329D709
| ML19329D709 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 02/11/1977 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Rodgers J FLORIDA POWER CORP. |
| Shared Package | |
| ML19329D710 | List: |
| References | |
| NUDOCS 8003160326 | |
| Download: ML19329D709 (3) | |
Text
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Distribut;_
Dccket Fil W. P. Gamill FEB 1119/fC PDR ELD J
LWR 1 File R. Reid D.B. Vassallo C. Nelson F.J. Williams D. Eisenhut Docket No. 50-302 J. Stolz K. Goller
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ACRS (16)
Florida Power Corporatin R.'
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ATTN: Mr. J. T. Rodgers D. Ross Assistant Vice President J. Knight.SS and Nuclear Project Manager R. Tedesco bcc:
J. R. Buchanan, NSIC "hn"re T.B. Abernathy, TIC S t..
eters ur Florida 33733 R. H. Vollmer Gentlemen:
M. L. Ernst
~
RE: CRYSTAL RIVER UNIT 3 NUCLEAR GENERATING PLANT On August 9,1976, Westinghouse Electric Corporation presented data to the NRC staff which showed that previously developed methods for accounting for the effect of fuel rod bowing on departure from nucleate boiling may not contain adequate themal sargin when unheated rods (such as thimble tubes) are present. We have evaluated the impact of the Westinghouse data on all operating pressurized water reactors (PWR's). Models for treating the effects of fuel rod bowing on themal-hydraulic perfomance have been derived for all PWR's. The models are based on the propensity of the individual fuel designs to bow and on the themal analysis mett.ods used to predict the coolant conditions for both nomal ' operation and anticipated transients.
The staff has reviewed the extent of rod bowing which occurs with Babcock &
Wilcox (B&W) fuel. Based oc this review, an equation was derived for the clearance reduction between fuel rods due to fuel rod bewing as a function of burnup:
AC = a + b AIu' G
where t>C is the fractional amount of closure G
Bu is the bundle average burnup, and a,b are empirical constants fitted to B&W rod bow data.
The reduction in departure frari nucleate' boiling ratio (DNBR) due to fuel rod bowing is assumed to vary linearly with the reduction in clearance between the fuel rods (or fuel rod and thimble rod) but can nevir be lower than that due to the 71tch reduction factor used in the themal analysis.
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DATE >
NRC PORM 318 (9-74) NRCM 0240 s.
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Florida Power Corporation FEB 11 1977 Babcock & Wilcox claimed and the staff approved credit for the following thermal margins:
Flow Area (Pitch). reduction Available Vent Yalve credit Densification Power Spike removal Excess Flow over that used in safety analyses Higher than licensed power used for plant safety analyses Based on this review and the thernial margins presented by Babcock & Wilcox to offset the new Westinghouse rod bow data, no reduction in DNBR is reouired for your facility at this time. Additional information on this review procedure, as well as more extensive background inforriation conterning rod bow, are contained in the enclosure to this letter.
Because future enanges in the thermal margin credits which B&W has claimed for your facility may require commensurate changes in the DNBR penalty, you are requested to submit, within 30 days, a list of the credits aoplicable to your facility for future reference on your d(eket.
Sincerely, Original Signedli[
John F.Stola 3 John F. Stolz, Chief Light Water Reactors Branch No.1 Division of Project fianagement
Enclosure:
Interim SER on Effects of Fuel Rod Bowing on Therma ~f ftargin Calculations for Light Water Reactors cc w/ enclosures: See next page LWR 1 LW l n
QLted.
JS.to.
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2/JL/77-2/$177--
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NRC FORM 315 (b76) NRCht 0240 W u. s. eovsanesen paumme orrecan sete-emesse
~' El F1orida Power Corporation cc: Mr. S. A. Brandimore Vice President and General Counsel P. O. Box 14042 St. Petersburg, Florida 33733 i
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.oc,. s skysk Form ABC 318 (Rev. Pb)) AEM 0240 W u. s. oovenmassar reinvene opricas sota.sae see
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