ML19290D511

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Forwards IE Info Notice 80-05, Chloride Contamination of Safety-Related Piping & Components. No Written Response Required
ML19290D511
Person / Time
Site: San Onofre  
Issue date: 02/08/1980
From: Engelken R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To: Papay L
SOUTHERN CALIFORNIA EDISON CO.
References
NUDOCS 8002220081
Download: ML19290D511 (1)
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UNITED STATES NUCLEAR REGULATORY COMMISSION y } )^9.,

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1990 N. CALIFORNIA BOULEVARD

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WALNUT CR EE K, CALIFORNI A 94596 February 8, 1980 Docket Nos. 50-206, 50-361 50-362 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rosemead, California 91770 Attention:

Dr. L. T. Papay, Vice President Advanced Engineering Gentlemen:

The enclosed IE Information Notice is forwarded to you for information.

No written response to this Information Notice is required.

If you have any questions related to the subject, please contact this office.

Sincerely, W -fL L R. H. Engelken Director

Enclosure:

IE Information Notice No. 80-05 cc w/ enclosures:

J. M. Curran, SCE R. Dietch, SCE 600M N

SSINS No.: 6870 Accession No.:

UNITED STATES 7912190673 NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGT0fl, D.C.

20555 c,

,rr February 8, 1980 e L=M IE Information Notice No. 80-05 CHLORIDE CONTAMINATION OF SAFETY RELATED PIPING Afl0 COMP 0NENTS A Bechtel Power Corporation Study at the Wolf Creek Project has revealed that a fire retardent coating is potentially corrosive in contact with stainless steel.

Albi "Duraspray" is a fire retardent coating which contains magnesium oxychloride, and is used for fireproofing of exposed structural steel in some Nuclear Power Plants. There appears to be no deleterious effect when it is applied over unprimed, inorganic zinc ated, or galvanized steel, however, it may be corrosive in contact with stainless steel, bare aluminum or copper.

Droppings or overspray of this material cannot be properly removed with water.

Diluted Nitric acid h5s been preven to be a useful cleanser, however, it presents a safety hazard.

Applicants and holders of construction permits and licensees of operating power reactors are advised to protect all stainless steel, copper and aluminum material from overspray and droppage of cementitious oxychloride materials and to remove accidently applied materials immediately and completely employing strict safety precautions d'uring the process.

Special attention should be given to weld areas ia any removal procedures.

No written response to this information notice is required.

If you require additional information regarding this matter contact the Director of the appropriate NRC Regional Office.

IE Information Notice No. 80-05 Enclosure February 8, 1980 RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued To Notice No.

Issued 80-04 BWR Fuel Exposure in 2/4/80 All BWR's holding a Excess of Limits power reactor OL or CP 80-03 Main Turbine Electro-1/31/80 All helders of power Hydraulic Control System reactor OLs and cps 80-02 8X8R '4ater Rod Lower 1/25/80 All BWR Facilities End Plug Wear holder power reactor OLs or cps 80-01 Fuel Handling Events 1/4/80 All holders of power reactor OLs and cps 79-37 Cracking in Low Pretsure 12/28/79 All power reactor OLs Turbine Discs and cps 79-36 Computer Code Defect in 12/31/79 All power reactor OLs Stress Analysis of Piping and cps El bow 79-35 Control of Maintenance 12/31/79 All power reactor facilities and Essential Equipment with an OL or CP 79-34 Inadequate Design of 12/27/79 All holders of power reactor Safety-Related Heat OLs and cps Exchangers 79-33 Improper Closure of 12/21/79 All power reactor facilities Prinary Containment holding OLs and cps Access Hatches 79-32 Separation of Electrical 12/21/79 All power reactor facilities Cables for HPCI and ADS holding OLs and cps 79-31 Use of Incorrect Anplified 12/13/79 All holders of power reactor Response Spectra (ARS)

OLs and cps 79-30 Reporting of Defects and 12/6/79 All power reactor facilities Noncompliance,10 CFR Part 21.

holding OLs and cps and vendors inspected by LCVIP 79-29 Loss of NonSafety-Related 11/16/79 All power reactor facilities Reactor Coolant System holding OLs or cps Instrumentation During Operation

NUREG/CR-0312 EFFECT OF SCALE ON TWO-PHASE COUNTERCURRENT FLOW FLOODING Final Report July 1977 - June 1978 H. J. Richter G. B. Wallis M. S. Speers Thaye School of Engineering Dartmouth College Prepared for U. S. Nuclear Regulatory Commission d

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NOTICE This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.

Available from National Technical Information Service Springfield, Virginia 22161

NUREG/CR-0312 R2 EFFECT OF SCALE ON TWO-PHASE COUNTERCURRENT FLOW FLOODING Final Report July 1977 - June 1978 H. J. Richter G. B. Wallis M. S. Speers Thayer School of Engineering Dartmouth College Hanover, PA 03755 Manuscript Completed: July 1978 Date Published: June 1979 Prepared for Office of Nuclear Regulatory Research U. S. Nuclear Regulatory Commission Washington, D.C. 20555 NRC FIN No. B5816

ABSTRACT Air-water countercurrent flow experiments have been performed in verti-cal tubes of different sizes and in annuli with different gao sizes.

The gas velocity sufficient to produce zero penetration of liquid in large tubes (6" and more) and annuli seems to be the same.

For 2" diameter tubes the floodinn behavior (an be represented by the Wallis correlation.

In large tubes and annuli it was assumed that all liquid penetrated in the form of a film along the walls. A force balance on this liquid film leads to a correlation, which predicts the flooding behavior in most cases satisfactorily.

iii

TABLE OF CONTENTS Abstract............................

iii Table of Cor tents v

List of Figures vii Ac knowl e d gme nt.........................

ix Abbreviations and Symbols x

1.

INTRODUCTION.......................

1 2.

TECHNICAL BACKGROUND...................

1 3.

EXPERIMENTAL FACILITIES 3

4.

EXPERIMENTAL RESULTS...................

5 Tube Experiments 5

Annu.lus Experiments.................

11 5.

ANALYSIS 16 6.

DISCUSSION........................

24 Zero Penetration 24 Flooding 28 Effects of Asymmetry 28 Effects of Inlet Water Momentum...........

28 7.

CONCLUSIONS..........................

28 8.

REFERENCES 29 Appendices A.

Data of Annulus Experiments 31 B.

Calculation of Liquid Volume Flow Rate for Nonsymmetri-cal Top Flood 39 Y

LIST OF FIGURES Figure 1 Experimental set up for flooding in large tubes 4

Figure 2 Nonsymmetrical flow skirt around the upper end of the pipe 6

Figure 3 llater injection through 1 and 2 inch diameter nozzles 6

Figure 4 Annulus test facility 7

Figure 5 Flow skirt for nonsymmetrical Water Flow into Annulus 8

Figure 6 Nondimensionless gas flux vs. water flux in diff-erent size pipe experiments 9

Figure 7 Flooding in 10 inch diameter tube with nonsymmetrical water flow from top, with several water levels in the upper plenum 10 Figure 8 Flooding in 10 inch diameter pipe with a water jet down through 2 inch' diameter nozzle 12 Figure 9 Flooding in 10 inch diameter tube with a water jet down through a 1 inch diameter nozzle 13 Figure 10 Flooding in a 10 inch diameter tube with a water jet down through 1 inch diameter nozzle in the center of tube 14 Figure 11 Nondimensional gas flux vs. water flux in the 1 inch annulus gap with different liquid levels in upper plenum.

Symmetrical top flood 15 Figure 12 Nondimensional gas flux vs. water flux in the 2 inch annulus gap with different liquid levels in upper plenum.

Symmetrical top flood 17 Figure 13 Nondimensional gas flux vs. water flux in the 1 inch annulus gap.

Comparison of symmetrical and nonsymmetrical top flood data for 0.0254 m (1") water level in upper plenum 18 Figure 14 Nondimensional gas flux vs.

water flux in the 1 inch annulus gap.

Comparison of symmetrical and nonsymmetrical top flood data for 0.1016 m (4")

water level in upper plenum 19 vii

Figure 15 Hondimensional gas flux vs. water flux in the 2 inch annulus gap.

Comparison of symmetrical and nonsymmetrical top flood data for 0.0254 m (1")

water level in upper plenum 20 Figure 16 Nondimensional gas flux vs. water flux in the 2 inch gap.

Comparison of symmetrical and non-symmetrical top flopd data for 0.1016 m (4") water level in upper plenum 21 Fi',ure 17 Nondimensional gas flux vs. water flux in the 1 inch annulus gap. Comparison with theoretical predic-tions 25 Figure 18 Nondimensional gas flux vs. water flux in the 2 inch annulus gap.

Comparison with theoretical predictions 26 Figure 19 Nondimensional gas flux J* vs. scale of experi-

aent 27 viii

ACKNOWLEDGMEllT This work was sponsored by the fluclear Regulatory Commission (NRC) under Contract No. NRC-04-76-329.

M ix

ABBREVIATIONS AND SYMBOLS A

flow cross section b

width C

constant in Wallis correlation eq.(1)

(C )$

interfacial friction factor f

C' constant eq.(12)

C, wall friction f actor D

tube diameter, hydraulic diameter D*

dimensionless diameter eq.(5) g gravity constant h

height jf liquid flux

.jp dimensionless liquid flux j*

dimensionless gas flux 9

j dimensionless liquid or gas flux eq.(2) j J{

dimensionless liquid or gas flux eq. (3)

Ku Kutateladze number eq.(4)

N Bond number eq.(14)

B 0

op*

Nondimensional pressure drop Ap* =

(fg D)

Q 11(!id or gas volumetric flux g

v

'liquia velocity f

v gas velocity g

vg interfacial velocity w

circumference 6

gap size 6

film thickness f

6' amplitude of wave f

p' weir coefficient Pf liquid density Pg gas density Pi liquid or gas density a

surface tension T

interfacial shear stress Tw wall shear stress X

EFFECT OF SCALE ON TWO-PHASE COUNTERCURRENT FLOW FLOODING 1.

INTRODUCTION The simultaneous flow of liquid down and gas up in a vertical conduit has its limitations.

The higher the gas flow rate up, the lower is the water flow rate which can penetrate down.

This limit of countercurrent flow is called " flooding".

It is of major importance in connection with Nuclear Reactor Safety and the operation of Emergency Core Cooling Systems.

Past experiments have resulted in a number of correlations to predict the flooding behavior.

Of special interest are the Wallis correlation, which describes the whole flooding curve, and the work of Pushkina and Sorokin, who measured the gas velocity necessary to prevent liquid penetration downwards.

The Wallis correlation has worked very well in small tubes.

Pushkina and Sorokin performad a rather thorough study nith air and water in various diameters to dete mine the zero water penetra-tion point.

Unfortunately, there is substantial disagreement between the Wallis correlation and Pushkina and Sorokin's work when the tube is 6 inches or rore in diameter.

In addition, it is questionable whether the above mentioned correlations can be used to describe flooding in reactor-like geometries such as an annulus.

The goals of this work were:

1) to determine which correlation, if any, describes zero penetration (i.e. duplicate or fail to duplicate Pushkina and Sorokin's work) in different size tubes and annuli; 2)to measure substantial portions of the flooding curve in different size tubes and annuli;
3) to derive an analytical model based on the observations in the experiment.
2. TECHNICAL BACKGROUND As a result of experimental studies of countercurrent flow several dimen-sional groups have emerged because they correlate flooding data quite well.

One equation in use correlates the liquid flux vs. the gas flux at the flooding limit (Wallis' correlation) jf + jp C

(1)

=

where jg and jp are the dimensionless fluxes of the gas and liquid pI ^ J '.

(2) jy = { g D(pf-p )} b g

1

with D the diameter of the tube or the hydraulic diameter of an annulus.

Some investigators claim that the circumference is more appropriate as the characteristic length than the hydraulic diameter for an annulus and define a flux p'

dj j

(3)

J*'

=

{g w(pf p )}

  • g where w = nD is the average circumference of an annulus. In both equations.i, h represents the velocity of gas or liquid if it would J

A flow alone in the cross section.

The other correlation deals with the extreme case of flooding, the zero penetration of liquid flow down. This theor.y claims that surface ten-sion is important in determining the limit to countercurrent flow, leading to the so-called Kutateladze number:

p*j

.Ku =

(4) 9 4

{g o(pf p g The ratio of Eq.(1) and (4) gives a dimensionless diameter. 9(P -p ) - k, f o D* = D (5) a From Eq.(1) we predict for zero penetration (jy = 0) the solution j* = C* b or 'j M D for constant thermodynamic properties. From Eq.(4) the zero 9 penetrati.on point is at j = const. for the same conditions. Thus an obvious contradiction bet 0een the two correlations occurs. While Eq.(1) would predict a larger and larger gas velocity with increasing pipe size, the second correlation claims that the gas velocity for zero penetration is virtually independent of pipe size. One could argue that in large tubes the criterion for zero penetration of liquid should be at Ku = const. if the liquid is in the form of a film much thinner than the tube diameter, so tha't surface tension is impor-tant for determining the " characteristic' dimension". In smaller tubes, where the tube diameter is the " characteristic dimension", the right criterion for zero penetration might be sought in j* = const. or b j mD. 9 A methodical approach to the influence of different scales on flooding phenomena has been started under this program. Tubes of different dia-meter were tested with symmetrical " top flood" (i.e. the water is sup-2

plied at the top of the tube rather than somewhere along the length) to measure the onset of.downwards water flow while air was flowing upwards in the pipe. Results have been presented by Richter and Lovell (1977). Since then the experiments were continued to include nonsymmetri-cal water injection into the tube to study the influence on the flooding behavior and a new test facility was built to provide experimental re-sults for annuli with two different gap sizes with symmetrical as well as nonsymmetrical top flood. 3. EXPERIMENTAL FACILITIES The first test facility for studying flooding in tubes of different sizes is shown in Figure 1. It consists of a vertical transparent pipe about 40 inches long and an upper and lower plenum. A 55 gallon drum was used to construct the upper plenum. Water enters through a 2 inch pipe into the upper plenum at rates up to about 250 gpm. An overflow was cut out of the side of the upper plenum and excess water is drained away via spillway. An aluminum bottom has been specially constructed and fitted to the bottom of the upper plenum. Using a neoprene gasket, the plexiglass " flooding tube" can be adjusted to protrude into the upper plenum as desired. The " flooding tube" is vertical and with square cut ends, unpolished. Experiments were performed in 2", 6" and 10" diameter pipes; all were 40-48 inches long. The lower plenum is also constructed from a 55 gallon drum. Air enters the side of the lower plenum via a 10 inch pipe. Water reaching the lower plenum (water " penetration") is allowed to collect, and thus the penetration volumetric water flow rate Q is measured. f Both upper and lower plena have plexiglass windows to allow observation of entrance / exit conditions of the flooding tube. The lower plenum can be drained by means of a tight closing bucterfly valve in the drain-age pipe. Air flow into the lower plenum is controlled by butterfly valves and measured by an orifice plate and pressure taps leading to a manometer. The air supply is a 75 H.P. blower with a maximum flow rate of 2100 scfm at a maximum pressure rise of 5 psig. 3

upper plenum N N Elbow-fleter I air test _.9 section T Bypass \\,'l water /= l spray s / a[r l water O /l collector Orifice I i I ~"- ~~ ~ \\ air ompressor lower enum water drainage Figure 1 Experimental set up for flooding in large tubes

This test facility was later modified to allow nonsymmetrical top flood experiments, see Figures 2 and 3. For the first tests of non-symmetrical water inflow into the flooding tube a skirt extending 3 inches above the upper end of the test section was wrapped.around 2700 (3/4) of the cir-cumference of the test pipe. This provided water flow into the test section only from 1/4 of the circumference as long as the liquid head in the upper plenum above the tube was smaller than the skirt height of 3 inches. For the second series of tests the water was inserted directly down into the flooding tube through either a 2 inch or 1 inch exit diameter nozzle, see Figure 3. The second test facility was built around an annulus test section, see Figure 4. The plexiglass tube for the annulus has an inside diameter of 17.5" and is approximately 40" long. Two interchangeable inner tubes (core) have 15.5" and 13.5" outside diameters thus providing annulus gap sizes of 1" or 2". The upper and lower plena are 40" diameter barrels with plexiglass windows. The water that penetrated into the lower plenum was collected there. For the air supply and the measurement of the air flow the same facility was used as for the tube experiments. The annulus test fa.cility was mod-ified to al. low nonsymmetrical top flood as well. As in the tube experi-ments a flow skirt was wrapped around L700 (3/4) of th'e anhulus. It extended about 9 inches above the top of the outside flooding tube,see Figure 5. This provided water flow into the annulus only from 1/4 of the circumference, thus encouraging a nonsymmetrical behavior. 4. EXPERIMENTAL RESULTS TUBE EXPERIMENTS The experimental results of the symmetrical top flood experiments in tubes were presented by Richter and Lovell (1977). It was found that for zero penetration in large tubes a " '.ateladze number of approximately 3.2 seems to be appropriate. The flooding curve, plotted on j* coordin-ates was found to be dependent on the size of the pipe. Experimental results with a 2" diameter tube resembled the Wallis correlation very ~well, while the flooding curve shifted with increasing pipe size to smaller values of the dimensionless fluxes jp and jg,(see Figure 6). The nonsymmetrical top flood experiments were performed in the 10" diameter tube. The results with the flow skirt around the top of the test section show essentially the same flooding behavior as was observ-ed with the symmetrical top flood in the 10" diameter tube (see Figure 7). At low gas flow rates the liquid flow rate down is not limit-ed by flooding but rather by the flow.estriction due to the flow of water over the top end of the pipe, which can be compared to the flow over a weir. The theoretical points on the curve when the liquid volume flow rate.is equal to the gas volume flow rate (Q = Q ) were obtained by cal-g f

4 h i _ _ _ _ _,I l I I I I I l I ,1 / l _ 10" & m Figure 2. Ilonsymetrical flow skirt around the upper end of the pipe h 3" l il l: l I- ", '--/ l l n l7 T. l I + 2" t* !- l l l l I .l l l i I 7 10" 4 Figure 3. llater i'njection through 1 and 2 inch diameter nozzles 4

Upper plenum ~ _ _ _ _ _ _ _i [ t Air and ^ entrained Air in m I water out 7 I e I _ )r - ' - - - - - 1,f ~ ~y ,p ,Tg, r lg Water in 'g 4 i p I I I s I I a -- Drainage upper u i I plenum I L-g t I I I l l y Annulus 8 I I Core 8 i / 8 P I I I 3 e.,U _.._.__.t$. l L _ _ _ v _ _ _ I *. ? 1 Water Air Lower plenum 7 Drainage

3. f t lower plenum Figure 4.

Annulus test facility 7

8 i Air out Air in + llater I entrained ]l I i i _ _ _ _. _ e t '- - - - - '-l y i....,.~--,_ Ils.' 8 I '.. - _ .ll : liater in d s Flow skirt 8 i "I""9" - s -,) Annulus t I e Flow skirt --) 90E ~ ~ ( l Figure 5 Flow' skirt for nonsymmetrical water , low into annulus s 8

1 0.9 O 2" pipe - single set of measurements ,q 9 0.8 o 6" pipe - single set of measurements 0.7 g O.6 o 10" p!pe - result of many measurecents 0 0.5 D D

  1. 3 h = 0.7 0.4 3,b 0

DO 0.2 o 0.1 0 0.8 0.9 1 0.1 0.2 0.3 0.4 0.5 0,6 0,7 Osh f Figure 6. flandimensional gas flux vs. water flux in.different size pipe experiments 9

0.8 ,g llater level in upper plenun 9 0 0.0254 m(1")o theoretical values frQ Q = a 0.0508 n(2") A g 7 0.6 o'0.0762 m(3")n 0 0.1016 m (4") O aO j**+j** = 0.7 f 9 0.4 OM approx. \\ ca curve of data O 2 CO O from Richter and Obg O Og -6 O M _ O O a O o O A a O A a o 0.2 O A O O O A O O O A oo W -- ~ ~ 4 __ ~ 0 ~. - - - 0 0.1 0.2 0.3 O.'s 0.4 f Fiqure 7. Flooding in 10 inch diameter tube with nonsynmetrical water flow from top, with several water levels in the upper plenug 10

culations of flow over a weir (see Appendix B ). At low gas flow rates the deviation from the theoretical maximum water flow becomes more pro-nounced at higher water levels in the upper plenum. This is probably due to the restriction of the flow from the walls of the flow skirt. It was observed that the flow over the weir converged more at higher water levels. The theoretical point for a water level of 4" was not plotted since there was also water flowing over the top of the flow skirt into the flooding tube (flow skirt height was 3"). The following experiments were perfonned with a water jet pointing down into the flooding tube. The nozzle was inserted off center of the flooding tube (see Figure 3) in order to create a highly nonsymmetri-cal flow in the tube. It was speculated that the momentum of the jet would increase the water penetration. As can be seen from Figure 8 the penetration is enhanced compared to the data from Richter and Lovell. The maximum water velocity exiting from the nozzle was approximately 4 m/s (for 125 gpm) for the 2 inch diameter nozzle. A substantial increase in penetration was achieved for the same liquid flow rates through a 1 inch diameter nozzle,(see Figure 9). This smaller nozz.e resulted in a water momentum sixteen times as large as for tne 2 inch diameter nozzle at the same flow rate, increa' sing the penetidtion rate for some cases above the Wallis correlation. The limits of water penetration at low gas flow rates are equal to the water injedian rate, where jf in " 5f down because no water is being ex-pelled into the upper plenum. Positioning of the nozzle exactly in the center of the flooding tube (only the 1" nozzle was used) increased the penetration rate of water slightly,(compare Figures 9 and 10). This is probably due to the fact that less water of the jet impinges on the wall of the tube in this case. As soon as water impinges on the wall, a film is formed which travels upwards at the high gas velocities. ANNULUS EXPERIMENTS The experiments in the annulus test facility were performed to obtain data on zero penetration as well as to measure the flooding curve. Since it was found in the tube experiments that the flooding behavior depended upon the water level in the upper plenum as long as the water level was lower than 4", this water level was one variable in these experiments. Quite extensive measurements have been done to verify the zero penetration point, which was found to be in the range of a Kutateladze number of 3.4 for the 1" gap and about 3.0 for the 2" gap. The zero penetration was found not to be a function of the water level in the upper plenum. Yet the flooding tests showed a strong dependency of water level on flooding behavior for water levels smaller than 4" (see Figure 11 for experimental results of the 1" annulus gap). As a reference line the Wallis correlation is plotted with a constant of C = 0.7 (all data points of the annulus experiments are listed in Appendix A). The points on the Q = Qf line are measured water pene-g 11

0.8 jh 9 Water flow rate in: 0.6 o 55 gpm A 90 gpm 00 O O 125 gpn b% i 13 \\ AA 00 di + J = 0.7 O O 0D g \\ / 0.4 N oCD 4% D O O \\ oT AM 000 ooo AA A 00 oo AAA % ' %oo approx. OO O[ curve for data @ ' ~ oA A OO from Richter and oo Lovell ggg 0.2 O co -AA-6 -OO ~ ~ 0 ~ j p'i

0. 4 0

0.1 0.2 0.3 Figure 8. Flooding in 10 inch diameter pipe with a water jet down through a 2 inch diameter nozzle. 12

0.8 3 0 j *'2 00 9 Ah Water flow rate in: o 55 gpm O O O 0*6 ~ A 90 gpm a) O OM O 125 ppm /h. O "O O OO j*2= j*fh = 0.7 o 0.4 g 'N 0 0.2 0=Of 9 __6_ _ -o ~ ~ ~~ 0 O o1 0.2 0.3 31 . 3 0,4 f Figure 9. Flooding in 10 inch diameter tube with a water jet down through a 1 inch diameter nozzle 13

Water flow rate: 0.8 g MA 000 o 55 gpm OO A 90 gpn j *i*. 9 AA 00] 0 125 gpu AAAOOD Co AAA 0.6 oo ^^^Fl]O 000 00 O ooo AAA 00 000 600 p p j *, + j y, = 0. 7 0.4 000 AA 00 000 000 OD 0.2 Q = Qg 9 -b -O" ~~~ - y ~~-~ ---o-0 0 0.1 0.2 15 0.3 0.4 3 *f Figure 10. Flooding in a 10 inch diameter tube with a water jet down through a 1 inch diameter nozzle in the center of tube 14

llater level in upper plenum O 0.0127 m (0.5") O 0.0254 m (1") 00.0381m(1.5") 1 6 0.0508 m (2") j*h Q 0.1016 m (4") 9 0 0.1524 m (6") 0.9 0.8 O O$- 0.7 OO O O 0.6 O@ O 60 0 % o 04 O O Q OS@ 0'5 6 O ~ 99 o 06 0 0.4 o 6 0 00 0.3 a . h = 0.7 j*g + 3*f 0.2 & m h ~~~~~ _ - g o, a-a-0 Ci 0 0.1 0.2 p.3 0.4 0.5 0.6 0.7 0.8 3.h 0.9 1 f Figure 11 Nondinensional gas flux vs water flux in.the 1 inch annulus gap with different liquid levels in upper plenum. Symmetrical top flood. 15

tration rates when the blower is not running. The gas volume in the lower plenum is displaced by the penetrating water volume, thus Qg = Qf. There is a large difference in water penetrating for the differ-ent water heights in the upper plenum. For the same gas flow rate (jg = const.) the water penetration rate increases with increasing water level, up to water heights of 2" to 4" above which there is no difference in flooding behavior. In the tube experiments, where similar observa-tions were made, this was attributed to liquid " bridging" in the upper plenum causing the gas to bubbla through the water. Figure 12 shows the flooding behavior for the annulus experiments with a 2" gap. The results show clearly two distinctly different classes of results, a lower penetration rate for water levels up to 2" in the upper plenum and one for water levels of 4" and above. The drop off of the high water level data (4"and 6") at high water penetration rates is probably due to the fact that these rates are close to the maximum water flow which can be provided. As mentioned before, exoeriments were performed in the annulus test facility witn a nonsymmetrical top flood as well. A flow skirt was wrapped 2700 (3/4) around the top of the annulus extending 9" above the top of the annulus. In Figure 13 the symmetrical top flood data are compared wi.th the nonsymmetrical flow results for water levels of 1" and in Figure 14 for 4" above the annulus in the upper plenum for a 1" annulus gap. Penetration rate is enhanced for the nonsymmetrical top flood, e.g. for a water level of 4" and a gas flux of j*h 0.55 thewaterpenetrationrateisj[2 =.0.6 instead of jf = 0.4 for the emetrical top flood, which means an increase in penetration rate of more than a factor of two. Zero penetration occurs at the same gas flux independent of whether the water is supplied symmetrically or nonsymmetrically. For a 2" annulus gap with nonsymmetrical top flood we see a very similar trend. The penetration rate increases for the nonsymmetrical top flood (see Figures 15 and 16 ). 5. ANALYSIS The analysis used by Richter and Lovell to predict the flooding behavior in tubes can also be used for flooding in the annulus. This theory assumes that initial penetration occurs in the form of a thin annular film. This film is balanced against gravity by wall shear T and inter-g facial shear forw T Thus a force balance can be set up between j the weight of a film and the shear forces: 6 (pf-p ) g (6) T + T = y 9 f g where 6f is the average film thickness. 16

flater level in upper plenum O 0.0127 m (0.5") 1 0.0254 m (1") 0.0381 m (1.5") 0 0.0500 m (2") 0.5 5 O 0.1016 m (4") 3 *1 9 0 0.1524 m (6") 0.8 0.7 O 0.6 -@ Q O U5 09 Oh 0.4 og Oo g j,, jp2 = 0.7 0.3 1 0 0.2 q,q 9 0.1 \\ o- - 0 W'i N. e i e i 0 0.1 0.2 0.3 0.4 0.5 0.6 O.7 0.3 0.9.J3 1 d i Figure 12 flondimensional gas flux vs. water flux in the 2 inch annulus gap with different liquid levels in upper plenum. Symmetrical top flood. 17

I j*b 9 0.9 0 0.8 - (D 0.7 0 0 n nsynnetrical top flood O 0.6 0 0 0 0.5 0 0 0 Og 9 symmetrical top flood 0.4 /, O O O 0.3 0.2 ., q 09 0.1 p -0 0 " -O ' 0 i e i 0 0.1 0.? 0.3 0.4 0.5 0.6 0.7 0.8 d.S 0.9 1 f Figure 13 flondimensional gas flux vs water flux in the 1 inch annulus Dap. Comparison of synnetrical and nonsymmetrical top flood data for 0.0254 m (l) water level in u'pper plenun. 18

1 0.9 m

  • 35 U bO 9

0.8 9 O o O 0.7 0 O 0.6 p c O' 00 O o 0 0 0 0 0.5 7 symmetrical top flood 000 o O o 0.4 O 0.3 0.2 Q"Of q p 0.1 4 0 i I t I g g [ g g g s 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 *ls 0.9 1 f Figure 14. Nondimensional gas. flux vs. water flux in the 1 inch annulus gap. Comparison of symmetrical and nonsymmetrical top flood data for 0.1016 m (4") water level in upper plenum. 19

= 1 j*b 9 0.9 0.8 0.7 _9 0.6 -Og g nonsymetrical top flood O'.5 0 U o O o-0.4 0 O o 0.3 g,._ symetrical top flood 0.2 O o=Qf 9 O~~~ ~ _ o ~. 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 4 0.9 1 3,f Figure 15 Nondimensional gas flux vs water flux in the 2 inch annulus cap. Comparison of synnetrical and nonsymmetrical top flood data for 0.0254 m (1") water icvel in upper plenum. 20

1 0.9 j*h ~ 9 0.8 0.7h o o ao 0.6 g Oog o O n nsymetrical top flood 0 0 0.5 symmetrical 0 O 0 0 0 0.4 - top flood 0 0.3 0 0.2 0.1 -O 0 t f g g g g s 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 3,3 f Figure 16 ilandimensional gas flux vs. water flux in the 2 inch annulus gap Comparison of symmetrical and nonsymmetrical top flood data for 0.1016 m (4") water level in upper plenun. 21

The wall shear stress can be expressed in terms of the average liquid velocity v f f C, pf v (7) 2 T = f g where C is a wall friction coefficient. We will set C,= 0.005 in a g smooth pipe. The interfacial shear force on this film is taken to be, j=(C)$fp(v + v )2 (8) T f g g g where v is the gas velocity and v is the liquid film surface velocity. g 4 Since the film is rather thin compared to the total cross section even g:j and in an annulus, we can introduce v g D d v = f 46 f f where D is the hydraulic diameter. In the case of an annulus the hydraulic diameter D is twice the gap size, thus in equation (9) it is assumed that both walls of the annulus are wet and the film thickness on both walls is the same. As was observed this is not the case in all experiments. At low water levels in the upper plenum the outside wall reemed to carry most of the water flow, while on the inside wall a much thinner film was penetrating. Thus in the theoretical calculations it was assumed either that both walls were covered.by an identical film or that the outside wall alone carried the entire flow. The interfacial film velocity v$ was assumed to be much less than the air velocity i.e. vj j and therefore was neglected in this. analysis. The interfacial fric!ioncoefficientcouldthenbe taken from cocurrent flow, see Wallis (1969). 6 (C )$ = 0.005 (1 + 300 ) (10) f Introducing these assumptions, substituting Eqs. (7), (8), (9), and (10) into (6) will give a function relating j jo and the film thickness 6.The film thickness 6 has to be. estimated. p,f fve assume a wave I f f shaped as in the sketch we can write a force balance between the stag-nation point in front _ of the wave and the top of the wave, the pressure fvf N P i N NN 6'f sss[ h y difference between these two poin$s is approximately the dynamic head of the 22

gas if we neglect the wave velocity, thus we can write: 8 I 2 6, =2-oy f gg or 2 6'= (11) f p 2 99 Wallis suggests that for cocurrent flow the roughness of the film 6'= 46. Introducing this we get for the film thickness f f I P gg and more generally, for a wave of unknown shape with j = v we get g o (IE) f 2 It was found that C'= 0.375 eems to work rather well in connection with the annulus experiments. Introducing Eq.(12) into Eq.(6) will give a result resembling a flooding correlation ~ Introducing C = 0.005, g C' = 0.375 and the nondimensional fluxes we obtain: 1.33 = jg2 [1 + 8.9x10 'f1 d + .0x10" N ' d d (13) 8 g B g f where 2 g D (pf_p ) II4) NB" o is the so called Bond number (Wallis 1969). For zero penetration,jp = 0, we obtain for the gas flux '-1+/1+4x1.33x8.9x10't;B 2 j* = 9 2x8.9x10~'i1 8 if 4x1.33x8.9x10-' NB >> 1 or NB >> 21 (16) 23

The gas flux at zero penetration becomes approximately independent of the gapsizeandwegetfromeq,(15) j = 3.5 (17) g which is equivalent to a.Kutateladze number 3.5 (18) Ku = j* N = B which was approximately the value observed in large pipes and in the annulus. The Bond number of a 1" annulus gap and air-water is approximately N = 350, thus eq.(16) is satisfied. B The flooding correlation of eq. (13) was used to compare with the experi-mental result. If only one wall is assumed to be wet the liquid flux is approximately only half the value calculated in this equation. The agreement between the theoretical predictions and the experiments is satisfying, especially for the 1" gap (see Figures 17 and 18). 6 DISCUSSION ZERO PENETRATION There is some uncertainty in measuring the air velocity needed to prevent penetration of the water into large tubes as well as in annuli. In this work it was found that zero penetration in large tubes (6" or more) can be predicted with a Kutateladze number of approximately Ku'= 3.2. In the annulus experiments the zero penetration in the 1" gap evaluated at approximately Ku = 3.4 and in the 2" gap at Ku = 3.0, but for the non-symmetrical top flooding experiments in the 2" gap it was closer to Ku = 3.2. Thus in general a Ku = 3.2 as predicted by Pushkina and Sorokin will predict zero penetration to about 7% accuracy for the results obtain-ed here. It is not certain if this can be said for larger scale annuli. Rothe et.al.(1978) suggest zero penetration for a constant dimensionless J* with 'the circumference as a characteristic length, (see Eq.(3)). This mEans that the gas velocity for zero penetration should increase with increase in scale. In Figure 19, J* is plotted versus the scale of differ-9 ent annulus experiments. At smal1 scales the constant gas flux seems to be appropriate, which is equivalent to tFe Wailis correlation. The experimental results presented here seem to indicate that a deviation from this line might occur at larger scale. Whether or not data from larger systems can be predicted by a Kutateladze number is too early to predict at this point. Larger scale tests should allow better conclu-sions to be drawn; at 1/10th scale the difference between the predictions of the J* and Ku theories is too small to be discriminated by the preci-sion of the experiments. 24

g. 3* 9 0.9 0.0 k f> c e 2 4 p. 0.5 D g &o OS g ' ~O-0.4 bo p th walls wet ~ ene wall wet O 0.3 jd*,+ 3.h = 0.7 f 0.2 Of Go. 5 / / A 0.1 O/ / / 0 / / 0 O.1 0:3 0.5 0.7 0.B 3,4 9 O Figure 17 tiondinensional gas flux vs. water flux in the 1 inch annulus gap. Comparison with theoretical predictions. 25

1 j*b 9 0.9 0.8 h. 0.7 0.6 O 0.5 \\ 09 00Og 0.4 a ,both walls wet 0.3 c6 ~N a one way; ggt 0.2 ~ " 0*l 0 =Q f 1' 0.1 O- - a o 0 0*1 0.2 0,3 04 0.5 0.6 o,7 08 5 0.9 y Figure 18 Hondinensional gas flux vs. water flux in the 2 inch annulus gap. Comparison with theoretical predictions. 26

Scale of Dartmouth annulus iair-water test facility 0.2 \\ i x x x \\ \\\\ \\ NN\\N \\ \\ -"v x N K y' n \\ J* scaling e No i x O h \\ N 'k g 0.15 R \\ \\' i s s Nc .o x Ni s o O 3, \\ N 'NofN 'J e + N9 "g. \\ s\\h#4 \\ 4,\\*'%, 8 + 8' kti\\ s 'QD N 4 \\ l a s 0.1 i O.03 0.04 0.05 0.07 '0.1 0T15 0.2 I i .i i 1/30 1/15 1/10 1/7 El Dartmouth air-water data Scale of Experiment O CREARE steara-water data gure n ensional C ux vs. scale of ex.e h nt. o O EARE tean-rater ata O Dartmouth air-water data

FLOODING While the.Wallis flooding correlation was confilmed in 2" diameter tubes, it was found that in large tubes and in annuli the flooding behavior could be predicted satisfactorily with a theory derived from a simple force balance on the liquid film penetrating down the wall, assuming the film thickness was limited by surface tension (Weber number effects). The assumption of only one or both walls wetted in the annulus seems to explain the differences in flooding behavior for different water levels in the upper plenum above the top of the annulus. For low water levels obvious-ly only one wall, in general the outside wall,seems to carry most of the liquid. EFFECTS OF ASYMMETRY Nonsymmetrical top flooding enhances the penetration rate only in the annulus. There it creates a highly nonsymnstrical flow pattern allowing much higher penetration rates at low gas flow rates. Close to the zero penetration point at relatively hig'1 gas flow rates the liquid entering the annulus is distributed around the annulus creating a very uniform flow pattern. Thus zero penetration occurs at approximately the same gas flux in symmetrical and nonsymmetrical top flooding. EFFECTS OF INLET WATER M0 MENTUM It was' found that water penetration could be enhanced by injecting the water from a tube or nozzle pointing downwards into the air flow. Though no quantitative understanding of this phenomenon has been reached in this study, this effect may explain se e of the influence of injected flow rate on water delivery in tests using a model of a PWR annulus and inject-ion of water through one or more of the " cold legs"

7. CONCLUSIONS
1) In both the 6" and 10" diameter tubes and the 17.5" 0.D. annulus with 1" or 2" gap the zero penetration point was predicted within 7% by a Kuta-teladze number of 3.2.
2) The air flow at the zero penetration point for the 1/10th scale annulus lies midway between the predictions of the J* = 0.16 and Ku = 3.2 theories and is only 7% from either of them.

Larger scale tests are needed in order to obtain a less equivocal discrimination.

3) The flooding data for the 2" diameter tube correlated with the Wallis correlation.

On the other hand, results from 6" and 10" tubes and from 28

the 17.5" 0.D. annulus were represented quite closely b' a theory based on a force balance for the falling film assuming a thi:.kness determined by a Weber Number criterion.

4) Both asymetry in the methods of introducing the water and introduc-tion in the form of a jet can increase the rate of penetration.

These effects have not been quantified in this work.

8. REFERENCES Pushkina, 0.L.; Y.L. Sorokin; Breakdown of Liquid Film Motion in Vertical Tubes.

Heat Transfer Soviet Research 1(1969)5 Richter, H.J.; T.W. Lovell: The Effect of Scale on Two-Phase Counter-current Flow Flooding in Vertical Tubes. NRCContractAT(49-24)-0329, August 1977 Rothe, P.H.; C.J.Crowley; J.A. Block: Progr.:ss on ECC Bypass Scaling. CREARE TN-272, NUREG/CR-0048, March 1978 Wallis, G.B.: One Dimensional Two-Phase Flow, McGraw Hill Book Company, New York 1969. 29

APPENDIX A. DATA 0F ANNULUS EXPERIMENTS 31

Experiment: 1 inch ann'ulus g3p - symmetrical top flood Water Volumetric Volumetric Height Gas Flow Water Flow j*' jf* AP* in Upper Rate Rate Plennum O O g f x 10~ m x 10 m'/s x 10~3 1 1 1 1 ~ m /s x 10~ x 10 8 0.127 1.0037 2.2472 4.3406 3.0852 0.300 0.127 2.0272 0.7874 5.7082 1.8263 0.700 0.127 3.2524 0.2144 6.9639 0.9529 1.050 0.127 4.1008 0.0670 7.6940 0.5326 1.200 0.127 5.5890 0.0000 3.8354 0.0000 1.30J 0.127 1.0122 2.0115 4.3320 2.91d9 0.3u0 0.127 0.0513 5.1282 0.8488 4.6507 0.000 0.127 2.5554 0.6079 6.3352 1.6047 1.150 0.127 1.9?22 1.2658 5.6S15 2.3155 0.350 0.127 1.6517 1.6667 5.3410 2.6570 0.400 0.127 1.3186 2.5000 4.9183 3.2541 0.400 0.127 1.1030 3.1250 4.5999 3.6382 0.200 0.127 0.8599 3.5714 4.1690 3.8894 0.150 0.127 0.7249 3.8462 3.8968 4.0363 0.100 0.127 0.5346 4.0816 3.4529 4.1580 0.100 0.127 0.4203 4.3478 3.1419 4.2914 0.060 0.127 0.0606 6.0606 0.9227 5.0667 0.000 0.254 1.0389 2.2523 4.3802 3.0637 0.250 0.254 1.7115 1.2781 5.3879 2.3268 0.350 0.254 2.4710 0.5187 6.2160 1.4322 0.450 0.254 2.9333 0.2449 6.6453 1.0164 0.450 0.254 3.6514 0.2525 7.4146 1.0342 1.000 0.254 0.9858 2.2436 4.2970 3.0827 0.500 0.254 5.4360 0.0000 B.7506 0.0000 1.500 0.254 5.2468 0.0052 8.6113 0.1485 0.650 0.254 3.145B 0.3683 6.9288 1.2491 1.200 0.254 3.5480 0.2494 7.2883 1.0278 1.100 0.254 3.7458 0.1537 7.4408 0.8069 1.000 0.254 4.0637 0.0960 7.7082 0.6378 1.000 0.254 4.4606 0.0397 8.0186 0.4100 1.300 0.254 5.0489 0.0181 8.4835 0.2767 0.800 0.254 0.9253 3.3019 4.2968 3.7398 0.350 0.254 1.1165 2.0202 4.5251 2.9253 0.200 0.254 1.3211 1.0018 4.8456 2.7626 0.200 0.254 3.9590 0.1894 7.6773 0.3957 2.100 0.254 0.0972 9.7222 1.1687 6.4173 0,000 0.254 1.7742 1.5873 5.5398 2.5930 0.450 0.254 1.5643 .2.6571 5.3542 3.4788 0.500 0.254 1.2879 3.0303 4.9267 3.5327 0.550 0.254 1.0336 4.7619 4.624d 4.4911 0.450 32

cont'd: 1 inch annulus gap - symmetrical top flood Water Volumetric Volumetric y g

Height, Gas Flow Water Flow jg jp Ap*

in Upper Rate Rate Plenum q g x 10 m x 10-2m*/s x 10 m'/s x 10 1 x 10 I -3 1 0.254 0.9094 5.5555 4.4206 4.8510 0.350 0.254 0.6786 6.8966 3.9684 5.4046 0.200 0.254 0.4821 8.3333 3.5021 5.9412 0.050 0.254 0.0909 9.0909 1.1301 6.2054 0.000 0.381 4.0371 0.1535 7.7163 0.8064 2.200 0.381 3.4391 0.4785 7.2467 1.4236 2.450 0.381 2.7970 0.7042 6.6275 1.7271 2.400 0.381 2.0365 1.6807 5.8556 2.6681 1.500 0.381 0.9961 2.4096 4.-3280 3.1948 0.750 0.381 0.1167 11.6667 1.2dO2 7.0297 0.000 0.381 1.3205 2.3256 4.9211 3.1386 0.650 0.381 1.8246 1.7699 5.6207 2.7381 0.300 0.381 1.5688 4.2553 5.4864 4.2455 0.650 0.381 1.7075 2.1739 5.5028 3.0345 1.100 0.381 1.8370 1.8182 5.6465 2.7751 0.800 0.381 1.2954 6.8966 5.2152 5.4048 0.703 0.381 1.0675 7.4074 4.8129 5.6014 0.400 0.381 0.9193 8.6957 4.5910 6.0690 0.400 0.381 0.7149 9.0909 4.1601 6.2054 0.250 0.381 0.4951 9.5238 3.5800

t. 3514 0.u50 0.381 0.1167 11.6667 1.2802 7.0297 0.000 0.508 3.0370 0.6515 6.9138 1.6612 3.300 0.508 4.3767 0.0779 7.9894 0.5744 2.650 0.508 5.0402 0.0284 8.4976 0.346,9 2.300 0.508 2.3283 1.6129 6.2250 2.6138 3.150 0.508 3.9570 0.1505 7.6477 0.7983 2.500 0.508 5.5687 0.0000 8.8621 0.00J0 2.0.0 0.508 5.4886 0.0000 8.7981 0.0.000 2.000 0.50.8 0.9924 3.0702 4.3907 3.6062 0.850 0.508 1.2528 3.3333 4.9078 3.7576 1.000 0.508 0.9413 3.9216 4.3658 4.0756 0.900 0.508 0.1429 14.2857 1.4167 7.7789 0.000 0.503 1.7804 2.8571 5.6876 3.4788 1.000 0.503 1.5025 4.2553 5.3867 4.2455 0.900 0.508 1.2854 7.6923 5.2516 5.7081 0.600 0.508 1.3977 8.0000 5.4556 5.8212 0.700 0.508 1.6671 4.2553 5.6528 4.2455 0.600 0.508 1.1346 8.8889 5.0343 6.1361 0.450 O.508 0.9316 9.0909 4.6402 6.2054 0.350 0'.508 0.6888 10.0000 4.1240 6.5003 0.270 33

cont'd: 1 inch annulus gap - synnetrical top flood Water Volumetric volumetric lleight Gas Flow Water Flow 3,b 3h op* in Upper Rate Rate 9 f Plenum x 10 m x 10~*m'/s x 10 m'/s x 10- 1 1 1 3 x 10~ 0.508 0.5244 10.5263 3.6976 6.6774 0.300 0.508 0.1167 11.6667 1.2802 7.0297 0.000 1.016 2.06S9 2.2989 6.0292 3.1205 3.400 1.016 2.9809 0.9434 6.9202 1.9990 4.250 1.016 3.6946 0.4274 7.5172 1.3454 4.000 1.016 4.1880 0.1377 7.8704 0.7638 4.u00 1.016 4.7819 0.0402 8.3096 0.4127 3.500 1.016 1.7719 3.2258 5.7248 3.6955 3.600 1.016 1.4204 3.8462 5.2245 4.0363 2.200 1.016 1.0579 6.7308 4.7734 5.3395 2.000 1.016 5.0696 0.0347 8.5514 0.3835 3.500 1.016 5.5513 0.0000 8 8556 0.0000 3.400 1.016 1.0671 7.6923 4.8357 5.7081 1.900 1.016 1.7525 3.8462 5.7330 4.0363 1.400 1.016 1.5172 4.6512 5.4310 4.4386 1.300 1.016 1.2291 8.0000 5.1690 5.8212 1.200 1.016 1.0229 14.2857 5.0120 7.7789 1.000 1.016 0.8541 14.2857 4.6550 7.7789 0.400 1.016 0.6901 17.3913 4.3284 8.5829 0.400 1.524 5.1334 0.0000 8.4811 0.0000 4.400 1.524 0.9894 8.3333 4.7241 5.9412 3.200 1.524 4.6310 0.0673 8.2175 0.5341 4.500 1.524 3.9378 0.2759 7.7008 1.0810 4.700 1.524 2.1350 2.4096 6.1142 3.1948 5.350 1.524 0.9269 10.2941 4.6739 6.6033 2.800 1.524 1.6246 4.4444 5.5917 4.3339 2.300 1.524 1.3717 5.4795 5.2597 4.8176 2.100 1.524 0.9416 13.4615 4.8320 7.5512 1.650 1.524 0.8046 15.3846 4.5707 8.0725 1.700 34

Experiment: 1 inch annulus gap - nonsymmetrical top flood Water Volumetric Volumetric Height Gas Flow Water Flow in Upper Rate Rate j*b jp' ap* 9 Plenum I x 10~1 K 10 m'/s x 10~ m /s x 10_I x 10 1 3 3 m 0.254 1.0822 3.2787 4.5322 3.7266 0.0d0 0.254 1.6704 3.2737 5.5316 3.7266 0.200 0.254 2.5338 1.2270 6.4494 2.2798 2.250 0.254 3.7199 0.1739 7.4370 0.85S3 1.750 0.254 3.6316 0.1734 7.3435 0.8571 1.650 0.254 4.4119 0.0678 7.9910 0.5359 1.500 0.254 5.5964 0.0000 8.8609 0.0000 1.400 0.254 U..'370 3.7037 0.7213 3.960.3 0.u00 0.254 1.7066 3.5651 5.6427 3.8860 0.150 0.254 1.4871 3.5088 5.2812 3.8552 0.100 0.254 1.0195 3.5273 4.5052 3.8654 0.050 0.254 0.0318 3.5083 4.1093 3.8552 0.050 0.254 0.5697 3.5398 3.4955 3.8722 0.000 0.254 1.9321 3.4733 5.9338 3.8334 0.150 0.254 0.0374 3.7383 0.7247 3.9793 0.000 1.016 1.0037 7.2917 4.7180 5.5575 1.250 1.016 2.1225 4.0616 6.26G2 4.15o0 4.'150 1.016 3.6286 1.1905 7.5994 2.2456 4.200 1.016 0.1129 11.2903 1.2594 6.9154 U.000 1.016 4.1979 0.5420 8.0110 1.5152 3.000 1.016 4.6763 0.2825 8.3361 1.0939 2.700 1.016 5.7132 0.0000 d.9923 0.0000 2.000 1.016 1.7355 7.7519 5.9723 5'.7302 1.500 1.016 1.9139 6.2696 6.1606 5.1533 5.150 1.016 1.5014 8.5106 5.6552 6.0041 1.000 1.016 1.0924 10.2041 5.018. 6.5744 0.750 1.016 0.8242 10.4790 4.4630 6.6623 0.500 1.016 0.6048 10.5422 3.9418 6.6824 0.350 1.016 0.1087 10.8696 1.2357 6.7854 0 000 35

Experiment: 2 inch annulus gap - symmetrical top flood Water Volumetric Volumetric Ileight ' Gas Flow Water Flow J, 3,f 3p, a in Upper Rate Rate g Plenum Q Q g f 2 10 m x 10 m /s x 10-3 1 1 1 1 m /s i 10 i 10-3 8 0.127 0.0532 5.3191 0.5303 2.9120 0.000 0.127 4.1120 1.2303 4.9490 1.4007 0.250 0.127 4.7707 0.8889 5.2444 1.1904 0.35u 0.127 5.4753 0.5391 5.5588 0.9270 0.450 0.127 6.8850 0.0694 6.0891 0.3327 0.430 0.127 8.6347 0.0LJD 6.7702 0.0000 0.020 0.127 4.9979 0.5993 5.3463 0.9779 0.500 0.127 3.3791 1.7391 4.5341 1.6651 0.200 0.127 4.0503 1.2270 4.8908 1.3986 0.250 0.127 3.7195' l.5267 4.7200 1.5601 0.250 0.127 2.9738 2.1053 4.3017 1.8320 0.180 0.127 2.5575 2.8986 4.0679 2.1496 0.150 0.127 2.0936 3.7453 3.7657 2.4435 0.150 0.127 1.6924 4.2105 3.4517 2.5908 0.100 0.127 1.0555 4.7619 2.8407 2.7552 0.100 0.254 0.1143 11.4286 0.7773 4.2684 0.000 0.254 4.1580 1.3072 4.9678 1.4436 0.400 0.254 4.7004 1.0929 5.2364 1.3200 0.500 0.254 5.55'79 0.4988 5.5965 0.8917 0.700 0.254 6.8753 0.0392 6.0731 0.2499 0.500 0.254 8.6535 0.0000 6.7690 0.0000 0.020 0.254 3.6984 1.5504 4.7135 1.5721 0.400 0.254 3.2376 1.9512 4.467' 1.7637 0.400 0.254 2.8803 2.4845 4.26'.2 1.9902 0.400 0.254 2.4635 3.1250 4.0163 2.2320 0.250 0.254 2.0768 4.2105 3.7818 2.5908 0.250 0.254 1.6894 5.0633 3.4903 2.8411 0.200 0.254 1.0491 7.4906 2.9283 3.4556 0.150 0.381 0.1364 13.6364 0.8491 4.6625 0.000 0.381 4.0457 1.7467 4.9446 1.6687 0.500 0.381 4.6960 1.2539 5.2521 1.4139 0.700 0.381 6.7052 0.0422 6.0095 0.2592 0.700 0.381 8.6472 0.0000 6.7629 0.0000 0.050 0.381 1.0469 8.3333 2.9543 3.6448 0.250 0.381 1.5523 5.1948 3.3771 2.8778 0.250 0.331 2.1790 3.8095 3.8479 2.4644 0.370 0.381 2.6687 2.7506 4.1449 2.0971 0.550 0.381 3.1385 2.3256 4.4344 1.9255 0.450 0.381 3.4782 1.8519 4.6135 1.7182 0.430 0.503 3.9746 1.0433 4.9176 -1.7142 0.600 36

cont'd: 2 inch annulus gap - symmetrical top flood Water Volumetric Volumetric Gas Flow Wat# Flow j,b j. 3p* Height Rate Rate 9 f in Upper Plenum O O g f 1 1 3 1 x 10 m x 10 m /s x 10 m /s x 10-x 10 1 8 8 0.508 4.8860 1.0336 5.3365 1.2d36 0.900 0.508 4.6859 1.2422 5.2524 1.4073 0.850 0.508 6.6017 0.1101 6.016o 0.4190 0.900 0.508 9.0893 0.0000 6.9427 0.0000 0.020 0.508 3.8891 1.8921 4.8640 1.7368 0.620 0.508 3.4102 2.0408 4.5807 1.8037 0.500 0.508 2.9371 2.7027 4.3257 2.0757 0.500 0.508 2.5421 3.6697 4.1069 2.4187 0.550 0.508 2.1497 4.2105 3.8381 2.5908 U.450 0.508 1.6907 5.1282 3.4995 2.8593 0.350 0.508 1.1270 8.1633 3.0370 3.6075 0.250 1.016 3.73.03 4.5977 4.9438 2.7073 1.250 1.016 5.4321 1.2500 5.6402 1.4116 1.670 1.016 4.8036 2.6144 5.4232 2.0415 1.620 1.016 6.3664 0.3086 5.9376 0.7015 1.580 1.016 7.6638 0.0447 6.4468 0.2670 0.600 1.016 9.1104 0.0000 6.9570 0,0000 0.250 1.016 1.0914 10.2564 3.0619 4.0436 0.900 1.016 1.5802 9.3023 3.5547 3.8599 0.400 1.016 2.1209 8.6957 4.0016 3.7232 0.950 1.016 2.5103 7.1429 4.2483 3.3745 0.950 1.016 3.1063 5.4054 4.5921 2.9355 1.050 1.016 3.4201 4.6512 4.7549 2.7230 1.120 1.524 3.6138 3.8835 4.8510 2.4882 1.500 1.524 5.0200 1.1527 5.450v 1.3556 2.000 1.524 4.3467 2.4845 5.1817 1.9902 2.000 1.524 5.9233 0.6061 5.7922 0.9829 2.250 1.524 7.6512 0.0785 6.4599 0.3537 1.400 1.524 9.0413 0.0000 6.9438 0.0000 0.080 1.524 3.2792 4.7619 4.6788 2.7552 1.750 1.524 2.8810 6.4516 4.4881 3.2070 1.750 1.524 2.4267 8.8889 4.2?.97 3.7644 1.750 1.524 2.1123 9.0909 4.0106 3.8069 1.250 1.524 1.3754 10.3627 3.3777 4.0645 1.350 37

2 inch annulus gap - nonsymmetrical top flood Experiment: Water Volumetric Volumetric U,h jf.b ap* ileight Gas Flow Water Flow in Upper Rate,Q Rate, Q g g f Plenum x 10~m x 10' m /s x 10 m'/s x 10-1 1 3 1 3 x 10' ~ 2 O.254 2.2914 3.4433 3.9293 2.3446 0.020 0.254 1.8044 3.4483 3.5216 2.3446 U.020 0.254 0.6143 3.4783 2.2018 2.3548 0.010 0.254 4.6547 3.4247 5.3831 2.3366 0.600 0.254 5.2217 1.1111 5.5086 1.3303 0.9JJ 0.254 5.3339 1.0363 5.5610 1.2d53 0.65] 0.254 5.5830 3.7191 5.6491 1.0709 0.d00 0.254 0.0339 3.3393 0.4234 2.3247 0.000 0.254 6.5277 0.1304 5.9546 0.4560 J.750 0.254 6.2508 0.2433 5.8623 0.o22d 0.700 0.254 5.5353 0.4854 5.7677 0.3797 0.700 0.254 5.7135 0.6579 5.6870 1.0241 0.700 0.254 5.1065 1.2121 5.4578 1.3901 0.800 0.254 4.9792 1.4493 5.4141 1.5200 0.800 0.254 4.6652 3.1746 5.3721 2.2496 0.80J 0.254 4.1394 3.4783 5.0937 2.3548 3.200 0.254 3.5850 3.3398 4.7603 2.3247 0.120 0.254 2.6379 3.3398 4.1367 2.3247 0.050 0.254 8.6332 0.0000 6.7410 0.0000 0.100 1.016 0.1575 1.5.7430 0.9125 5.0105 0.000 1.016 2.3848 15.6250 4.3578 4.9909 0.200 1.016 6.3309 3.3333 6.2329 2.3052 2.000 1.016 6.0305 4.0404 6.1321 2.5379 1.850 1.016 5.5537 5.1471 5.9650 2.8645 1.750 3.016 4.9571 6.1162 5.6986 3.1226 1.700 1.016 4.2300 7.2202 5.3433 3.3927 1.700 1.016 3.0357 10.9589 4.7316 4.1798 1.600 1.016 2.5915 13.7931 4.4957 4.6892 1.450 1.016 8.1770 0.7220 6.7977 1.0729 2.120 1.016 9.7953 0.0000 7.2149 0.0000 1.250 1.016 7.2517 1.8957 6.5293 1.7364 1.900 1.016 7.7379 1.2963 6.6730 1.4375 1.250 1.016 7.0365 2.3256 6.4553 1.9255 1.200 1.016 5.8325 4.7619 6.043d 2.7552 1.150 38

APPEfiDIX B. CALCULATI0fl 0F LIQUID VOLUME FLOW RATE FOR fl0ftSYMMETRICAL TOP FLOOD (FLOW OVER A WEIR) In the diagram (see Figure 7) with the experimental results for nonsym-metrical top flood theoretical points are also plotted, where the liquid volume flow rate is equal. to the gas volume flow rate (Q = Q ). These g f points were obtained by calculation of the flow over a weir, which is hub h /2 g h (A1) Q = f where u is a weir coefficient, usually p = 0.63, b is the width of the weir, in this case one quarter (900) of the circumference as long as the water height is less than 3 inches and h is the water height above the weir. For the nondimensional flux we receive then for the water flow down i f pf >> pg s /2 bh jy = 3 (A2) with D the diameter of the pipe and since Q = Q g f p i. jg = ( j' jp (A3) 39

U S. NUCLE AR REGUL ATORY COMMISSION BIBLIOGRAPHIC DATA SHEET NURSG/CR4312 4 TITLE AN D SUBTI TLE (Add Volume No, of appropriate) 2 (Leave blankt Effect of Scale on Two-Phase Countercurrent Flow Flooding 3 RECIPIENT'S ACCESSION NO. ---Final Report

7. AUTHOR (Si
5. DATE REPORT COVPLE TED lYE**

MONTH Richter, llorst J. ; Wallis, Graham B. ; Speers, Mark S. August 78 9 PERF ORMING ORGANIZATION N AME AND M AILING ADDRESS (/nclude leo Codel DATE REPORT ISSUED Thayer School of Engineering, Dartmouth College, l YEAR vosTs llanover, New Hampshire 03755 6 (Leave Wonk) 8 (Leave blank) 12 SPONSORING ORG ANil ATION N AME AND M AILING ADDRE SS (Include lep Code) O PROJECTiTASK/ WORK UNIT NO Division of Reactor Safety Research

11. CONT R ACT NO WRSR/SEB NRC-04-76-329 13 TYPE OF REPORT PE R!Oo COVE RE D (/nclus+e datest Final Report on Contracted Research July 1, 1977--June 30,1978 15 SUPPLEMENTARY NOTES 14 (Leave olan4 )

16 ABSTR ACT (200 *ords or less) Air-water countercurrent flow experiments have been performed in vertical tubes of different sizes and in annuli with different gap sizes. The gas velocity sufficient to produce zero penetration of liquid in large tubes (6" and more) seems to be the same. For 2" diameter tubes the flooding behavior can be represented by the Wallis correlation. In large tubes and annuli it was assumed that all liquid penetrated in the form of a film along the walls. A force balance on this liquid film leads to a correlation, which predicts the flooding behavior in most cases satisfactorily.

17. KE Y WOR DS AND GOCUME NT AN ALYSIS 17a DESCRIPTORS II)CA ECCS ECC Bypass Flooding 17b IDENTIFIE RS' OPE N EN DE D TE RMS 18 AV AIL ABILITY STATEMENT 19 SE CURITY CLASS (Tms eporrt 21 NO OF PAGES unclassified 20 SECURITY CLASS (Ths panel
22. P RICE S

N RC FORM 335 67-77)

UNITE D ST ATES I l NUCLIAH REGULATORY COMMISSION W ASHINGTON. O. C. 20555 POST AG E ANO F E E S P AID u.s MucLE AR REGuL ATOM a OF F ICI A L B USI N E SS COMW'SSION PE N ALTY FOR PRIV ATE USE. 5300 LJ}}

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