ML20138N172

Justification for Use of W-3 Correlation for Millstone Unit 3 Steamline Break Analysis

ML20138N172
Person / Time
Site:	Millstone
Issue date:	10/14/1985
From:	WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19344C131	List: B11831, Forwards Proprietary & Nonproprietary Supplemental Info Re, Justification for Use of W-3 Correlation For...Steamline Break Analysis, in Response to 850925 Telcon.Proprietary Version Withheld (Ref 10CFR2.790) ML20138N161 ML20138N172
References
NUDOCS 8511050093
Download: ML20138N172 (4)

Text

, ..', .

Vestinghouse Proprietary Class 3 JUSTIFICATION FOR THE USE OF THE V-3 CORRELATION FOR THE MILLSTONE UNIT 3 STEAMBREAK ANALYSIS Reference 1 describes the results of applying the U-3 correlation over its original pressure range, 1000 to 2300 psia. The mean measured-to-predicted critical heat flux ratio and sample standard deviation from that analysis are shown in Table 1.

For the Millstone Unit 3 Cycle 1 steambreak analysis the pressure is

[ ]**'" psia at the limiting (i.e., minimum DNBR) statepoint in the transient. The following information provides the justification for using the W-3 at this low pressure.

Reference 2 contains the results of an analysis of low pressure (700 -

1000 psia) data using the W-3 correlation. Those data were taken from .

the same sources as those used in the development of the W-3 correlation. As shown in the attached figure (taken from Reference 2) no anomalous behavior is observed for the low pressure data.

The V-3 correlation statistics have been recalculated for the extended database. The revised statistics are essentially unchanged from the original values (Table 1). The limic DNBR was also recalculated using the method of Owen (Reference 3). As shown in Table 1, the revised correlation statistics demonstrate that there is a 954 probability with 95% confidence that DNB will not occur if the minimum DNBR is maintained in excess of 1.31. Again, this value is essentially unchanged from the limit DNBR associated with the original database.

This evaluation demonstrates that extending the pressure range of the W-3 correlation database *by a significant amount has a negligible effect on the correlation statistics. Therefore, use of the 1.3 limit DNBR for the Millstone Unit 3 steambreak analysis is justified.

8511050 PDR WOB h PDR ADOCK k23 A

Westinghouse Proprietary Class 3 The results of the Millstone Unit 3 Cycle 1 steambreak analysis indicate that the minimum DNBR exceeds the design basis limit of 1.3.

In fact the minimum DNBR is actually in excess of 1.8. Thus, any uncertainties associated with the calculation of a DNBR slightly b ov the pressure range of the data shown in the figure are ar a

~

compensated by the actual calculated DNBR.

References

1. Tong, L. S., " Prediction of Departure from Nucleate Boiling for Axially Non-Uniform Heat Flux Distribution, " J. Nuclear Enerry, Vol. 21, pp 241-248 (1967).

2. Prairie Island FSAR Amendment 20, p. 14.2-30, Docket #50-282, August 4, 1972.

3. Owen, D. B., " Factors for One-Sided Tolerance Limits and for Variable Sampling Plans," SCR-607, March 1963.

• O .w Westinghouse Proprietary Class 3 l

TABLE 1 1 V-3 CHF CORREIATION STATISTICS l

Sample Pressure Range Number of _

Standard (esia) Data Points M Deviation Limit DNBR 1000 - 2300 809 0.996 0.132 1.30 700 - 2300 885 1.001 0.137 1.31 O

i 1

l 8

CO 0 0 O

O Oo O O e@ 6 o

0 8

O

. O s

e s.

J

?

a.

~

m O O .C C @ O O Og CD CD O b G @

O O

- o O ,

f f I t 1 I 1 . 9 e c

. e o "T3 2**H ENG (paanstaH/passipa2d)

! (Fredicted/. Measured) Dbli Heat Flux vs Pressure Figure 14.2-11 l

_ _ _ _ . ___ _ _ _ _ . _ - - _ . _ _ _ . - _ - .