ML17338A718

DNBR Safety Limit for Cobra Iiic Analysis

ML17338A718
Person / Time
Site:	Turkey Point
Issue date:	03/31/1979
From:	Irani A, Wilson W, Wyrick R FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17338A717	List: L-79-127, Submits Analysis Supporting Amend to App a of Licenses DPR-31 & DPR-41.DNBR Safety Limit of 1.24 Is Consistent W/Cobra Iiic Computer Code.Forwards DNBR Safety Limit for Cobra Iiic Analysis ML17338A718
References
NAD-2199, ZAR-790331, NUDOCS 7905250430
Download: ML17338A718 (32)

Text

NAD 2l99 DNBR Safety Limit For COBRA XXX C Analysis March l979 A. Xrani W. Wilson R. Wyrick Reviewed By K

Date 3 O'7 Approved By

Manager, Nuclear Analysis Dept..

Date

/Z~ ~

NAD-QR-87 Florida Power and Light. Company Miami, Florida

~i D

1.

Xntroduction The objective of this investigation is to determine a

DNBR limit for thermal hydraulic calculations performed with the COBRA XXX C code for Turkey Point. Units 3 and 4.-

The Turkey Point core loading consists of Westing-house 15xl5 fuel with L-grid spacers.

On the basis of data from 91 test points obtained fzom Columbia University test bundle experiments and des-cribed in WCAP-7988 (reference 1), Westinghouse, in reference 2, derived a

DNBR limit of 1.24 as the value that bounds 95% of the 91 point. data base with 95-confidence.

The predicted values of critical heat flux.

were calculated with the THXNC computer code using the W-3 critical heat flux correlation and the L-grid correction.

However, as reference 1 is a Westinghouse proprietary report, this data base was not available for dizect compazison with COBRA III C results.

Xnstead, COBRA XXX C results have been compaxed with'hose ob-tained with the Westinghouse THINC code for a data base (reference

3) suggested by the NRG (reference 4).

This data base consists of 284 DNB data points obtained with 12 different test sections.

These test sections covered a variety. of heat flux distributions, different heated lengths of rods, and several lengths of axial spacings between grids.

Some test sections had spacer grids with mixing vanes and some had no vanes.

For the COBRA study, five of these test sections, those corresponding most closely to the L-grid geometry of the Turkey Point fuel, were selected for data comparison.

A total of 3.17 points were thus compared.

2.

Results The statistical analysis of the 117 data points from reference 3 performed by FPL with the COBRA XII C/MIT code yielded a DNBR limit of 1.1870 while the DNBR limit:

calculated from THINC DNB heat fluxes given in reference 3 for the same data points was 1.1564.

Therefore,. it was concluded that the COBRA DNBR limit is 1.1870 1.0265 1.1564 times the DNBR limit obtained with the,THXNC code.

As discussed

above, the DNBR limit for the THXNC code with the L-grid correction is 1.24.

Therefore, the corres-ponding COBRA XIX C DNBR limit is 1.24xl.0265=1.273.

IQ'

TABLE I RUN NO.

PRESSURE (PSXA)

POWER AT DNB (MW)

INLET TEMP.

(.'P)

INLET BUNDLE AV.

MA(S VELOCITY (10 LBM/HR-PT (continued)

LOCAL DNB lO BTU/i(R-PX2 liEAS PRHD

'R PPPO 242 243 244 245 247 248 249 379 380 381 382 383 384 385 386 387 388 390 391 392 393 246 2413 2392 2412 2112 2102 1793 1813 1810 1854 1792 1848 2111 2112 2092 2098 2111 2417'408 2425 2403 2393 2102

2. 286

2. 426 2.656 2.410 2.713 2.508 2.658 2.700 3.049 2.688 2.827 2.703 3.010 2 '74 2.650 3 '04 2.743 2.845 2.983 2.732 2.998 2.583 558. 3 541. 0 514.3 537.7 499.7 499,. 7 477.7 587.0 568.0 562.0 540.0 608.0 588.0 603.0 578.0 573.0 624.0 602. 0 592.0 584.0 563.0 515.3 2.09 2.06 2.07 2.04 2.05 2.11 2.02 3.58 3.53 3.03 3.07 3.54 3.53 3.03

3. 08 3.03 3.71 3.10 3.00 2.53 2.51 2'6

.629

.782

.856

.663

.747

.733

. 77.7

.551

.672

.637

.711

.459

.614

.463

.628

.613 465

.483

.558

.511

.561

.711

. 705

.890 1.018

.699

.837

.835

~ 892

.505

.644

.630

.794

.393

.569

.404

.640

.568

.402

.433

.508

.467

~ 531

.784

.892

.879

~ 841

.948

.892

.878

. 871.

l. 091 1.044 1.011

~ 896 1.167 1.078 1.147

.982 1.079 1.158

.1. 116

1. 100 1.095 1.057

.907

TEST SECTiON XX RUNS 8

19 1.0 53 69 I

c 0.8-CQ n

0.6-Ch CO Q

c9'o.

o g

o e

o oyr o'

0 o

0.4 A

0.2 r

r r

0 0

0.2 0.4 0.6 0.8 q",

(PREDICTED)

X 10 BTU/HR-FT 6,,

2 FXGURE 1 8 FT USXNE U ROD BUNDLE WITH MIXING GRXD AT 20 XN SPACXNG.

COMPARXSON OF DNB DATA WXTH W-3 PREDXCTXONS FROM COBRA XXI.C SUBCHANNEL ANALYSIS A

I'

~

~ ~

~ ~

4

'4

~

~

I

0 i

3.

Test, Descri tion A,detailed description of the test bundles and ex-perimental arrangement is given in reference 3.

Two basic test section configurations were used in this analysis.

They were (1) a 9 rod bundle in a 3x3 square array with a 14 foot heated

length, anQ (2) a 16 rod bundle in a 4x4 square array with an 8 foot heated length.

The test bundles included both a u sin u and cos u axial heat flux distributions.

" The 14 foot. test section used a uniform radial power distribution and the 8 foot test section used a non--

uniform radial power distribution.

Various grid designs were utilized to maintain rod spacing for the test bundles.

For this analysis, ll7 DNB data points from test sections XX, XXX, VXX, VXXX, and XXX of Table XV of reference 3, were used.

Only test sections which included mixing vane grids (excluding the T-H type) were considered in orQer to be representative of FPL fuel assemblies.

4.

Data Anal sis The ratio of the measured heat flux for DNB to the predicted heat flux for DNB as well as the values of the heat fluxes, were calculated in a manner similar to that used by Westinghouse anQ described in reference 3.

Briefly, the method will be described here.

A.

The ratio of predicted to measured DNB heat flux

= was calculated by II q meas II pred Ps 1 e 0 +

0 ~ 03 (G

)

(

TDC

)

35 10 0-.019 2

= Local mass velocity, ibm /hr ft

= Thermal diffusion coefficient, G

TDC 0.061 for 20 in. grid span 0.051 for 26 in. grid span where Q

is the experimentally measured total bundle power (H$U) given in reference 3,

at, which DNB occurs for specified inlet conditions.

QXX is the total bundle power predicted by the COBRA XXX C code for a minimum DNBR of 1.0 for the specified inlet conditions using the I-3 critical heat flux correlation multiplied by the grid spacer correction factor, Fs, where

II

~

As an alternate

method, the spacer factor Fs could have been included internally in the COBRA calcu-lation of Q >.

Sensitivity studies showed that this would lead'o a lower DNBR limit.

Following the Westinghouse method described in reference 3,

of multiplying the predicted power by the spacer factor external to the code, results in a more conservative value for the DNBR limit.

B.

The value of the measured local DNB heat flux, q"

, was determined at the axial location of meas minimum DNBR for the bundle power Q

and the speci-fied inlet conditions. 'he predicted local DNB I

heat flux, q" d,

was. calculated from q" and pred meas the ratio descry.bed in part A, above.

5.

Derivation of DNBR Limit The experimental inlet conditions and values of pred meas pred calcul'ated by FPL using the COBRA XXX C code are presented in Table 1.

The DNBR safety limit for a 95x95 upper tolerance limit (i.e., the value of DNBR which bounds 95% of the data base with a 95%

confidence) is given by:

DNBR'imit =

95%95 Z is (q"

/q" d), the mean value of the measured to predicted DNB heat, flux ratios 0

is the standard deviation of the

ratios, q"

q meas q pred E95 95 is a multiplier to give a 95x95 upper tolerance limit for the number of~points, N, in the data base.

Values are taken from reference 5.

Ik

Por the 117 points analyzed:

N = 117 X = 0.9864 6 = 0.0756 K95 95 = 1.903 (reference 5) 95x95 DNBR Limit = 1.1870 Figures 1 through 5 show comparisons of q"

's meas q"

d for the test assemblies analyzed.

Figure 6

pred is a composite of all the data points analyzed.

The corresponding Westinghouse DNBR limit for the same experimental points is 1.1564.

The difference may be due to some of the conservatism in the COBBA calculations.

For example,. sensitivity studies showed that an increase in the number of axial nodes used in-the calculations would have decreased the DNBR safety limit calculated with COBM. and brought it, closer to the Westinghouse limit.

TABLE I RUN NO.

PRESSURE

~(PSXA POWER AT DNB (MW)

INLET TEMP.

( F)

INLET BUNDLE AV-MA$S VELOCITY (10 LBM/HR-FT LOCAL DNB 106 BTU/HR PT2 Il II MBAS

~. PRHD Il MEAS q

PRZO 8

9 10 11 12 13 14'5 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 4S 46 47 48 49 50 51 52 1504 1505 2150 2100 2401 2401 1508 1808 1811 1508 1504 1532 1504 lS14 1812 1843 2091 2091 2389 2391 2391 2397 2391 2394 2395 2394 2394 2395 2093 2095 2099 2096 2096 2095 2095 2095 1800 1799 1799 1799 2099 1796 1505 1500 1796 2.353 2.586 2.116 2.310 2.281 2.145 2.122 2.259 2.333 2.400 2.754 2.530

2. 722 2.837 2.649 2.854 2.414 2.708 2.515 2.692 2'09 2.563 3.000 2.565 2.937 2.321

2. 513 2.677 2.599 2.921 2,228 2.649 2.880 2.313 2.525 2.672 2.341 2.630 2.459 2.777 2;908

2. 629 2.565 3.066 2.718 520.0 499.0 584.0 567.0 577.0 559.0 560.0 579.0 500.0 545.0 482.0 466.0 495.0 483.0 519.0 501.0 564.0 544.0 581.0 564.0 543.0 620.0 601.0 605.0 582.0 560.5 543.0 520.0 596.0 579.0 602.0 577.0 561.0 544.0 518.0 501.0 580. 0 563. 0 559.0 540.0 524.0 494.0 541.0 514.0 482.0

2. 50 2.50 2.59 2.55 2.54 2.06 3.43 3.55 1.91 3.60 2.48 1.97 2.55 2.56 2.51 2.49 2.53 2.55 2.56 2.54 2.56 3.43 3.58 3.01 3.03 2.01 2.04 2.04 3.56 3.53 3.00 3.05 3.06 2.00 2.03

2. 04

3. 52 3.51 3.01 3.02 2.50 2.06 3.47 3'3 2.03

'870

.956

.699

.762

.843

793

.732

746

.862

.887 1.018

.935

.762

.795

.691

.799

.583

.654

.547

.650

.758

.496

.581

.497

.639

.560

.607

.698

.565

.635

.485

.640

.695

.558

.658

.697

.610

~.686

.641

.724

.758

.685

.669

.799

.709

. 845

.932

.650

.709

.832

.798

.775

.741

.844

.945

1. 000

.918

.821

.870

.735

.861

.579

~ 657

.523

.643

.777

.421

~ 519

.439

.592

.547

.609

.732

.532

.609

.445

.612

.685

.547

.680

.736

.637

.726

.665

.. 750

.778

.709

.744

.881

.737 1.029 1.026 1.075 1.075 1.013

.994

..945 1.006 1.022

.939 1.018 1.018

.929

.914

.941

.928 1 ~ 007

.996

1. 046, 1.011

.975 1.179 3.'. 121 1.131 1.079 1.025

.997

.954 1.062 1.043 1.090 1.046 1.015 1.020

.968

.947

.957

.945

.964

.966

.975

.967

.899

.907

.962

0

~i

RUN NO.

PRESSURE

~PSXll)

POWER AT DNB (MN)

INLET TEMP.

( F)

INLET BUNDLE AV.

HA$S VELOCITY (10 LBM/HR-FT TABLE I (continued)

LOCAL DNB

,)10 BTU/IIR-FT I(

HEWS fs q PRHD 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 206 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222

'23 224 225 226 227 228 229 232 233 234 235 236 237 238 239 240 241 1503.

1815.

1781.

2103.

2108.

2110.

.2114.

2115.

2129.

2097.

2104.

2108

'083.

2390 2404.

2407.

2414.

2084 2026

,1497 1497 1497 1491 1498 1801 1797 1790 1490 1490 1491 1510 1512 1796 1791 2103 2105 2103 2103 2113 2124

.2115 2422 2424 2415 2432 2424 2414 2413 2413 2388 2.105 2.508 2.474 2.366 2.279 2.103 2.420 2.519 2.262 1 999 2.857 2'73 2.563 2.476 2.158 1.949 2.079 2.431 2.884 2.686 3.058 3.340 2.498 2.905 2.626 2.836 2.782 2.418 2.665 2.861 2.278 2.668 2.257 2.797 2.232 2.428 2.630 2.235 2.513

~ 2.833 3.054 2.391 2.786 3.049 2.200 2.492 2 '90 2.431 2.711 2.835 558.0 560.0 481.5 502.5 517 '

541.5 545.0 567.5 581.0 601.5 566.0 594.0 577.5 580.0 602.0 623.0 627.0 579.3 536.7 525.0 499.5 478.3 566.3 536.7 566.3 568.7 501.0 516.7 496.7 481.0 559.7 539.3 580.7 560.'0 583.0 565.3 546. 0 599. 0 583.7 559.3 566.3 626.3 602.5 583.7 624.3 602.2 580.3 579.3 553.7 537.0 3.58 3.62 2.03 2.02 2.04 2.03 2.

53'.06 3.07 3.04 3.58 3.46

'3. 57 3.09 3.07 3.05 3.56 2.60 2.61 2.48 2.55 2.55 3.51 3.63 3.62 3.51 2.07 2.55 2.56 2.55 3.60 3.59 3.54 3.68 2.56 2.55 2.57 3.

10'.

06 3.10 3.56 3.54 3.61 3.59 3.03 3.06 3.09 2.58 2.57 2.56

.778

.927

.914

,.874

.842

.777

.894

..869

.780

.660

.964

.750

.884

.915

.712

.643

.686

.603

.795

.739

,.842

.919

.663

.800

.745

.725

.766 737

.779

.836

.666

.780

.621

.770

.593

.668

.724

.571

.667

.780

.873

.561

.. 713

. 839

.516

.637

.910

.669

.874

.914

.864

.967

.944

.944

.888

~ 785

.907

.853

.780

.620

.954

.730

.884

.950

.713

.580

.625

.587

.833

.730

.837

.919

.677

.882

.840

.725

.780

.843

.889

.907

.790

.905

.704

.845

.601

.701

.793

.582

.682

.853

.942

.522

.742

.908

.477

.648

.987

.724

.993 1.067

.901

.958

.968

.926

.948

.990

.986 1.019 1.000

, 1.064 1.011 1.028 1.000

.963

.999 1.109 1.098 1.028

.953 1.013 1.005 1.000

.979

.907

.887 1.000

.9Sl

.874

.876

.922

.843

.862

.882

.911

.986

.953

.913

.981

.979

.914

.927 1.075

.961

.924 1.081

~ 983

.922

.924

.880

.857

0

~ ~

REFERENCES

Cadek, F.F.

and Motley, F.E., Applications of Modified Spacer Factor for L Grid Typical and Cold Wall Cell DNB, WCAP-7988-P-A, January 1975 (Westinghouse Proprietary).

2.

Reavis, J.R. et. al., Fuel Rod Bowing, WCAP-8692,

December, 1975.

3.

Rosal, E.R. et. al., High Pressure Rod Bundle DNB Data With Axially Non-Uniform Heat. Flux, Nuc. Eng, Des., Vol 31, 1974.

4.

Letter A. Schwencer (NRC) to R.E. Uhrig (FPL), dated September 15,

1978, Dockets No. 50-250 and 50-251.

5.

Owen, D.B., Factors for One-Sided Tolerance Limits and for Variables. Sampling Plans, SCR-607, Sandia Corp.,

March 1963.

0 0

1.0 TEST SECTION III RUNS 20 -52 0.8 CA 0.6 Q)O r 0 OOP OO OC

~O 0

9

. Or OQ 0.4

=,

mlles 0.2 0

0 0.2 0.4 0.6 0.8 1.0 q"

(PREDICTED)

X 10 BTU/EER-FT 6

2 FXGURE 2

14 FT USXNU ROD BUNDLE WITH MXXING VANE GRID AT 20 IN SPACING.

COMPARISON OF DNB DATA WITEE W-3 PREDICTIONS FROM COBRA XXX.C SUBCEEANNEL ANALXSIS.

-il0 I

~ y s

<<v t

~

0 I

~

1.0 0.8 Pl C) 0.6 0.2 TEST SECTXON VXX RUNS 206 216

/

/

9 r

0 O

/0 0

<o r'/'

r r

rl r

0 0

0.2 0.4 0.6 0.8 1.0 c["

(PREDICTED)

X l0 BTU/HR-FT 6

2 FXGURE 3

8 FT COSXNE U ROD BUNDLE WITH MIXING VANE GRXD AT 20 XN SPACINGS COMPARISON OF DNB DATA NITH N 3 PREDICTXONS PROM COBRA XIX.C SUBCHANNEL ANALYSIS.

0

1.0 TEST SECTXON VIII RUNS 217 249 0.8 0.6 A

CO 41 0.4 lP A

U' I

~o (P

%@0 o

5 0

o ~

p 8

g)

B CD 0

0.2 0

0.2 0.4 0.6 0.8 1.0 q" NB (PREDICTED)

X 10 BTU/HR-FT FIGURE 4

8 FT COSINE U ROD BUNDLE WITH MIXING VANE GRID AT 26 IN SPACING.

CO~FARISON OF DNB DATA MXTH W-3 PREDICTXONS FRO~f COBRA XII.C SUBCHANNEL ANALYSIS.

-l2-=

1

~

a

0

1.0 TEST SECTION XXX RUNS 379 393 0.8 I

l4x 0.6 a

0.4 A

0.2

/'

/

o o

o o

CP

//

r

//

- i-i 0

0 0 ~ 2 0 '

0.6 0.8 q"

(PREDICTED)

X 10 BUT/kfR FT 1.0 FXGURE 5

14 FT COSINE u ROD BUNDLE NITkk MIXING VANE GRID AT 20" SPACXNG.

COMPARISON OF DNB DATA NXTlt N-3 PREDXCTIONS FROM COBRA XII.c SUBCHANNEL ANALYSIS.

41

1. 0" E~

0.8 CQ CO 0.6 Gl U) 0.2 0

TEST SECTXONS XIr IXXr VXX, VXXX, XXX r

r y r

r r

rrr rrr

/rr t x + 1<crj r

+)~/r "

9

+o rO g.'8 '~'-:%

r O~o 0

'b

"~o g~o>

O~

% Or r

PI A

~

0 0.2 0.4 0.6 0.8 1.0 q"

(PREDICTED)

X 10 BTU/$1R-FT FXGURE 6

COMPARISON OF DNB DATA NXTli N-3 PREDXCTIONS FROM COBRA XXX C SUBCIiANNEL ANALYSIS FOR TEST SECTIONS XX, XXX, VXX, VIIX AND XX'I 1

STATE OF FLORIDA

)

)

COUNTY OF DADE

)

Robert E. Uhrig, being first duly sworn, deposes and says:

That he is a Vice President of Florida Power 6 Light Company, the Licensee herein; That he has executed the foregoing document; that the state-ments made i;n this said docum'ent are true and correct to the best of his knowledge, information, and belief, and that he is authorized to execute the document on behalf of said Licensee.

Robert E. Uhrig Subscribed and sworn to before me this Q/ ~

day of l9 >'7 NOTARY PUBLI in and for the county of Dade, State of Florida HbtAI 'SUO CTATB,OI: NLORIDA IH ~ROg MY COMMISSION 'XPIRES MARCH 27,

$$Q My commission expires:

BOMDEO THRII MAYWARO BONDIHG

Cl

%i~z

'I I

1

sl 1

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