ML20092C087

Advises That Util Has Completed Performance Review of N16 Transit Time Flow Meter (Ttfm) During First Operating Cycle of Unit 1.Conclusions Re Installation of Subj Detectors Apply to Unit 2.Azimuthal Uncertainty Term Discussion Encl

ML20092C087
Person / Time
Site:	Comanche Peak
Issue date:	02/04/1992
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TXX-92057, NUDOCS 9202110263
Download: ML20092C087 (8)

Text

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Log # TXX 92057 1 .? File # 904 7 ,7 10010 ft/ ELECTRIC february 4, 1992 WiluamJ.CohH1Jr.

o w m emur.,

U. S. Nuclear Regulatory Commission i Attn: Document Control Desk '

Washington, DC 20555 ,

i

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET N05. 50 445 and 50 446 N16 TRANSIT TIME FLOW HETER (TTFH) l REF: NUREG 0797, Supplement No. 12. " Safety Evaluation Report related to the operation of Comanche Peak Steam Electric Station, Units 1 and 2." January 1990. >

Gentlemen:

TV Electric has completed a performance review of the N16 transit time flow meter  !

(TTFH) during the first operating cycle of Unit 1.  !

As.previously committed in the referenced document, this letter transmits the performance data collected and the associated conclusions. Specifically, Attachment 1 contains a detailed discussion of the azimuthal uncertainty term.

Tables 1 through 4 contain loop specific results from each of five test runs conducted on each loop. Figure 1 superimposes the tabulated test results on a diagrammatic representation of a hot leg cross sectional view.  !

From the analysis of the tabulated data, the TTFM uncertainty terms contained in Table 3 of the CPSES Improved Thermal Design Procedure report were shown to remain bounding. Therefore, the contribution of the TTFH volumetric flow rate uncertainty to the overall RCS flow rate uncertainty specified in the CPSES Unit 1 Technical Specifications also remains bounding.

In addition, due to similar installation of N16 detectors, these conclusions apply to the use of the TTFH on Unit 2.

0 92021 PDR 263 OCK Q Q pgh coRouve swa La.si D.nu.munmi P

s TXX 92057 Page 2 of 2 Documents supporting these conclusions contain Westinghouse proprietary information and are available for your review, Please contact Mr. J. D. Seawright at (214) 812 4375 should you hate any questions.

Sincerely, q 71 1 f, William J. Cahill, Jr.

By:

fflL! Y N_

Roger D. Walker 1

Manager of Nuclear Licensing JDS/grp Attachment c - Mr. R. D. Martin, Region IV Resident inspectors CPSES (2)

Mr. T. A. Bergman, HRR

.' Attach::nt to 1XX 920$7 Page 1 of 6 DISCUS $10N Or AZlHUTHAL UNCERTAINTY TERM

1. Current uncertainty uf the TTFM includes the fo110 wing:

• 1% flow systematic error (Westinghouse original value)

• 1.4075% flow random error ("NRC conservatism" factor)

!!. The NRC conservatism factor stemmed from a concern involving the deviation between velocities measured by the " top" and " bottom" detectors during testing (as documented in WCAP 9172). This testing was conducted on a two loop plant and involved limited N16 detector geometry variations. Since thu C95t$ N16 detector installation is asymmetric on one of four loops (see figure 1), analysis of actual test data allows the azimuthal profile to be determined.

!!!. Assume the azimuthal uncertainty is systematics Applying a least squares fit to the data tabulated in Tables 1 4, the azimuthal velocity profile was found to be well represented by the following relations velocity - 55.026 + 1.136 sin (theta + 58.66)

This demonstrates the symmetry of the azimuthal velocity profile. .

Consequently, the azimuthal error may be assumed to cancel out on the three loops with N16 detectors located 180 degrees apart. For loop four, with detectors _ spaced 150 degrees apart, a 0.28% flow error results due to the azimuthal term.

Therefore, treating the azimuthal uncertainty as a systematic term results in values of 0% flow error for 3 loops and 0.28% flow error for the fourth loop.- These values are significantly less than the currently assumed azimuthal uncertainties listed in item 1 above.

IV. Assume the azimuthal uncertainty is random:

Statistically, the tabulated data produce a standard deviation of the mean values equal to 10.535% flow (from the average flow velocities for each of the 4 loops). Statistically, this equates to a single loop value of 11.07% flow, which is only slightly 1arger than the 1% flow error _

assumed by Westinghouse. However, it must be noted that the currently assumed azimuthal uncertainty of 11% flow is treated as J n tu n11q in the TTIM overail uncertainty evaluation. -Treating the term ne. 't.ndom results in a significantly smaller overall TTfH error, even when substituting the slightly larger value of 11.07% flow, V. Therefore, independent of how the azimuthal error term is chosen to be treated (i.e. systematic or random), the tabulated performance data demonstrate that the current method / values and resulting TTfH volumetric flow uncertainty are conservative.

l

.' AttachCent te TXX 92057  :

Page 2 cf 6 TADLE 1 l RCS MEASURED 90T LEG COOLANT VELOCITIES (TifM DATA)  ;

COMANCHE PEAK UNIT 1 (CYCLE 1 NEAR E0L 7/16/91) i LOOP 1 MEA $URED COOLANT VELOCITIES (FT/SEC)

Top! Bottomi (Top Bottom)x100%  !

Detectors Detectors Averago Average  !

fittlurement iftlied ilt/Jgd (ft/5ec) (%)

l r

Run 1 54.701 55.083 54.892 0.70%

Run 2 $4.779 54.823 54.801 0.08% i Run 3 $4.742 55.392 $$.067 1.10%

Run 4 54.711 55.0$$ 54.883 0.63%

f Run 5 $4.747 $$ 451 $5.099 1,20%

Mean $4.736 $5.i61 $4.948 0.77% i Standard .0310 0.259 0.128 -- -

Deviation-Standard Error .0139 0.1160 0.057 -

l of Mean - ,

I for coolant loops 1, 2 and 3. the N*16 detectors are on the sides of the hot leg pipe. The detectors labeled " Top" are on the left when facing the reactor vessel.

L l -

l l

('

h l

.' Attach::nt to TXX 92057 Pag 3 3 of 6 i

I 1ABLE 2 RCS HEASURED HOT LEG COOLANT VELOCITIES (TTFH DATA) l C0HANCHE PEAK UNIT 1 (CYCLE 1 NEAR EOL + 7/25/91)

LOOP 2 HEASURED COOLANT VELOCITIES (FT/5EC)

Top 1 Bottomi (Top Bottom)x100%

Detectors Detectors Average Average  ;

tituurement ( f t /sec)_ LLtl.itu Iltlitu _ Lil_ j Run 1 56.094 54.579 55.336 2.74%

Run 2 56.113 54.829 55.471 2.311 Run 3 56.134 54.762 55 448 2.47%

P Run 4 56.000 54.791 55.396 2.18%

Run 5 56.047 54.763 55.405 2.32%

Mean 56.078 54.745 55.411 2.41%

Standard 0.0540 0.0966 0.0521 -

Deviation Standard Error 0.0241 0.0432 0.0233 --

of Mean 1F or coolant loops 1, 2 and 3, the N 16 detectors are on the sides of the hot leg pipe.- The detectors labeled " Top" are on the left when facing the  ;

reactor vessel. '

F

.. . _ . _ _ . . . . - . . . . . - . ~ . . . - . , . . ,-

Attach:ent to TXX 92057 Page 4 of 6 ,

TABLE 3 '

RCS HEASURED POT LEG COOLANT VELOCITIES (TTTH DATA)

COMANCHE PEAK UNIT 1 (CYCLE 1 NEAR COL 8/1/91)  !

LOOP 3 HEASURED COOLANT VELOCITIES (fi/$EC) -

Top % Bottom! (Top Bottom)x100% ,

Detectors Detectors Average Average '

Heasuremeni iltlien ifilitsl ILilien 1%) i Run 1 -$4,025 50.107 55.066 3.78%

Run 2 53.868 55.638 54.753 3.23%

Run 3 53.956 55.858 54.907 3.46% f i

Ruf, 4 53.993 55.906 54.950 3.48%

Run 5 54.116 55.940 55.028 3.31%

Hean 53.992 55.890 54.941 3.46%

Standard 0.0914 0.1693 0.1222 - '

Deviation

. Standard Error 0.0409 0.0757 0.0547 --

of Mean I for coolant loops 1. 2 and 3. the N 16 detectors are on the sides of the hot leg pipe. The detectors labeled " Top" are on the left when facing the reactor vessel.

k_ j

1 Attach:ent to TXX 92057

.' Page E of 6 TABLE 4 RCS MEASURED HOT LEG COOLANT V;,0 CITIES (TTFH DATA)

COMANCHE PEAK UNIT 1 (CYCLE 1 - NEAR EOL 7/2/91)

LOOP 4 HEASURED COOLANT VELOCITIES (FT/SEC)

Topi Dottom' (Top-Bottom)x100%

Detectors Detectors Average Average Hensurement . mlicsl . mlied. (Ft/Sc0 (%)

Run 1 55.850 53.766 54.813 3.78%

Run 2 55.742 54.142 54.947 2.91%

Run 3 56.034 53.886 54.960 3.91%

Run 4 55.820 54.204 55.012 2.941 L .Run f 56.018 54 076

. -55.048 3.53%

l Mean 55.893 54.017 54.9F5 3.41%  :

l:

Strandard 0.1200 0.1803 0.0895 ---

Devthtion Standard titor 0.0572 0.0806- 0.0400 ---

of Hean.

I For coolant loop 4. the detectors are near the top and bottcs of the pipe.

h -

• ~ Attachment to TXX-92057

._ Page 6 of 6-FIGURE 1 0

0 TOP U

15  !

HOT LEG PIP 1 55.893(4T)

" ADJACENT SIDE"

[ "0PP03ITC SIDE" 54.736 55.161(1B 270 - -

54 / # 56.078(2T -

- 90 0 53.992 55.890(3B l

avg = 55.064 ft/sec ADJACENT SAME LOOP LOOP HOT COLD LEG LEG 54.017(48) ..

' a 0

180 80TTON COMMANCHE FEAK UNIT 1 NEAR E0L TTFM

' Reactor coolant hot leg coolant velocities (ft/sec) mapped to loup 1 orientation facing reactor,

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