ML20063H262

Water Film Formation on AP600 Reactor Containment Surface

ML20063H262
Person / Time
Site:	05200003
Issue date:	02/17/1988
From:	Pieczynski A, Stewart W WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19303F868	List: ML20063H248 ML20063H262 ML20063H276 NRC-94-4056, Forwards Proprietary WCAP-13884,Rev 0, Water Film Formation on AP600..., & WCAP-13960,Rev 0, PCS Water..., & Non-Proprietary WCAP-13885,Rev 0, Water Film..., & WCAP-13961,Rev 0.WCAP-13884 & WCAP-13960 Withheld
References
WCAP-13885, NUDOCS 9402170217
Download: ML20063H262 (31)

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l l-WESTINGHOUSE CLASS 3 (Non-Proprietary) 0

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WESTINGHOUSE CLASS 3 WCAP-13885 WESTINGHOUSE PROPRIETARY CLASS 2 VERSION EXISTS AS WCAP-13884 WATER FILM FORMATION ON AP600 REACTOR CONTAINMENT SURFACE e

I i

WESTINGHOUSE PROPRIETARY CLASS 2 This document contarns mformation propnetary to Westeghouse Doctre Corporaten. A e submmed m conhdence and a to ts used solely for the purpose for whch a es l

fumsshed and retumed upon request This documerd and such informshon a not to be reproouced. transmitted, disclosed or used otherwse m whole or m part wnhout prior wmten authonzaten of Westinghouse Doctre Corporanon. Energy Systems Business Unit. s@ct to the negenas contained hereof b WESTINGHOUSE CLASS 3 (NON PROPRIETARY)

Y DOE DESIGN CERTIFICATION PROGRAM oovERNMENT UMITED RIGHTS STATEMENT (A) These data are submnted wah kmned nghts under govemment contract No DE-ACO3-eOSF18405 These data may be reproduced and used by the government witti l the express kmasten that they wdl not, wahout wrdten permissen of the contractor, be used for purposes of manufacturer nor disclosed outside the govemmers, except that the govemment may disclose these data outsafe the govemmerd for the fohowng purposes, al any, provced that the govemmeri maum such dsclosure sub act to l

i prohibmon agarrst further use and declosure (l) Ths "Proprotary Data' may be declosed for svabaton purposes under the restrctions above (ii) The " Proprietary Data' may be dsciosed to tre Doctnc Power Research instnote (EPRI). electne utelay representatives and their erect consultants. escludeng direct commercial competitors, and the DOE Natenal Laboratores under the prohibnions and restrctiom above (B) The no!ce shah be marked on any repodJct#on a these data, sn whoes or en part

(

U (C) WESTINGHOUSE ELECTRIC CORPORATION 1994 A beense a reserved to the U S Govemme1 under contract DE-AC0340SF18495 O DOE CONTRACT DEUVERABLES (DEUVERED DATA)

Subrect to specded exceptens. disclosure d this data a restrcted unhi Seprember 30,1995 or Desgn Certrication urcer DOE contract DE-AC03-90SFt 8495. whchever

{

m aster EPRI CONFIDENTIAUOBUGATION NOTICES: NOTICE: 1 2

304 sOCATEGORY: A BOC D

e rO.'.

i ARC rOAKE PROGRAM ARC UMrrED RIGHTS STATEMENT The proonetary data. turnshed under Subcontract Number ARC-93-SSC-001 wnh ARC may be dupicated and used by the govemment and ARC, sub eet to the hmnatens t

d Ancle H-17 F of that subcontract, wnh the exposs hmnatons that the propretary data may not be dec6 sed outsee the government or ARC. or ARC's Class 1 & 3 rnemters or EPRt or be used for purposes d mewfacture without peer permusen of the SLbcortractor. except that further dmctosure or use may be maae soley for the followmg pwposes The propoetary data may be decioned to other than commerent competnors of Subcontractor for evaluaten purposes of the subcontract under the restreten that the proprwtary data be retained m confidence and nos be further duelosed, and sub.ect to the terms of a non-disebswo agreemere between the Subcontractor and that orpararaten. excluomg DOE and as corecactors (C) WESTINGHOUSE ELECTRIC CORPORATION 1994 A heense e reserved to the U S Govemment unoer contract DE-FCO2-NE34267 and subcontract ARC-913-SC-001-0 ARC CONTRACT DEUVERABLES (DEUVERED DATA)

Subrect to speedied emceptons. enclosure d the data a restrcted under ARC Subcontract ARC-93-SSC@t.

Westmghouse Doctre Corporaton Energy Systems Busmess und Advance Technology B.miness Area P O Box 355 Pmsburgh. Penneyevann 15230 i

C 1994 Westnghouso Electne Corporaton All Rights Resefved 1

WESTINGHOUSE CLASS 3 Centrcct-Required Decument. Internci Water Film Formation on AP-600 Distribution only.

Reactor Containment Surface Thi, documeni i, not to se distributed outside the Westinghouse Electric Corporation.

(For information. contact Contracts Management.)

R&D Document No.

A. T. Pieczynski and W. A. Stewart 88-8E9-ADLWR-R1 Mechanical Systems ETD 2331 l

I l

February 17. 1988 Approved:

• 1 Nu "P'"

F. T. Thompson, General Manager Engineering Technology Division

@ Westinghouse R&D Center 1310 Beulah Road Pittsburgh, Pennsylvania 15235

)

l WESTINGHOUSE CLASS 3 i

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ENGINEERING TECHNOLOGY DIVISION ETD '2331 3

Research Report 88-8E9-ADLWR-R1 Contract Required Water Film Formation on AP-600 i

Reactor Containment Surface l

)

i n

Written by,

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A. T. Pieczynski v/

Heat Transfer & Fluid Dynamics Written by

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W. A. Stewart Mechanical Systems

[

Approved by A

J. A. Ciesar. Manager g

Mechanical Systems I

i i

Westinghouse Electric Corporation Research and Development Center Beulah Road.. Churchill Borough Pittsburgh. Pennsylvania 15235 l

'l

WESTINGHOUSE CLASS 3 l

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WESTINGHOUSE CLASS 3 Table of Contents Page Abstraet iii 1.

Introduction 1

2.

Film Flow Conditions...............

3 3.

Test Apparatus.

5 4.

Results 11 5.

Conclusions..

..................................................18 6.

References........

19 7.

N o m e n cl a t u r e.............................................................................. 20

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WESTINGHOUSE OLASS 3 e

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WESTINGHOUSE CLASS 3 ENGINEERING TECHNOLOGY DIVISION ETD :'131 Report 88-8E9-ADLWR-R1 Contr act Required Water F:Im Formation on AP-600 Reactor Containment Surface Abstract The new reactor. AP-600, is being designed for passive containment cooling of heat released following a design basis accident.

Natural draft air cooling and water film evaporation is to be employed. In order to determine if the containment surface can wet aasily and to evaluate ways to distribute a film tests have been conducted on a large coated steel plate. The surface does wet readily. Weirs, with and without fill material, curtains, and screens have been designed and evaluated for the flaw rates to be empicyed. The weirs and curtains can distribute water films well.

4 4

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WESTINGHOUSE CLASS 3 1

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WESTINGHOUSE CLASS 3 i

l 1.

Introduction i

i The new reactor. AP-600. is being designed for passive containment cooling of the heat released following a design basis accident. Steam generated by the pressurized water reactor is to be condensed on the inside of the containment, which is a one and three quarters of an inch thick wall steel pressure vessel. The heat conducts to the outer surface where it is transferred to an evaporating water film and ambient air flowing over the containment surface by natural draft. The containment vessel has an elliptical shape dome

.i o-#.

at the top and a cylindrical side wall in diameter. Water that has -

o.y been stored in tanks above the dome will be led to the top of the dome by t

gravity flow in pipes. For the initial flow length over the dome, water will heat sensibly and begin to evaporate. On the side wall. next to an upward l

flowing natural draft of air. a downward flowing water film will evaporate at a

.f temperature near 175'F.I in the first hour after a postulated accident. as

o..b 3

o,e much as i water flow is ' required. As the deca 1.b a,* b heat release de ses, less flow is required. At ten hours.

is needed. Initially. the film must cover about 75% of tne-

%b containment surface above the operating deck, while after ten hours. only about j

20% of the surface must be wet. For all times the dry part of the surface is i

)

being cooled by the natural draft of air.

The purpose of the work reported here is to determine if a painted containment surface will wet and if it will. how a film may be formed. Can j

)

water flow be. added at a few points on the containment dome and distribute itself naturally to form a film in a short distance? A simple test apparatus-was constructed to answer such questions. It is a flat steel plate. eight feet

[

long in the flow direction and four feet wide which is pivoted so that it can 4 l

WESTINGHOUSE CLASS 3 simulate nearly horizontal sections of the dome and vertical sections of the side wall.

It is unheated. Metered wa:er flow at the representative required rates was added at a point at one end. In addition. several devices to distribute water in a film were devised and tested. They were various designs of weirs.

curtains which formed variable area weirs, and screens.

If there is therrr.a!!y induced dry-pato.ing of the heated containment surface and run-off of thick water Ums around such patches, there may be insufficient wetted area to provide enough cooling. Redistribution might then be accomplished using devices similar to those that are used to form the film in the first place.

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WESTINGHOUSE CLASS 3 2.

Film Flow Conditions Theory for flow of laminar films is available from several references.2-3 The gravitational force equals the wall shearing stress times area. The mass flow per unit vridth of wall, G. for a vertical surface is:

2,3 G = pu,6 = "3 sin 8 (1) pu 6 for Rey =

= S < 300 (2)

P P

where u is average vel city and 6 is film thickness.

m

_ o-p If the maximum water flow.

reaches the top of the

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side wall whose perimeter is Yis 0.0737 lb /ft-s. Water at 175'F m

has p = 60.81 lbm/ft and p = 23.84 x 10-5 lb/ft-s.2 Then on the side wall 3

where g = 32.2 ft/s:2 6 (side wall) = 0.000762 ft = 0.00915 in "A

oib i

9 b ab On the elliptical dome whose radius is at the a., b

-,*,b radius, the angle of inclination is sin-3 j= 14.5*.

The flow cross-section perimeter is half what it is on the side, so G is double, and g sin 8 is i

one-fourth because of the small inclination. Thus 6 will be more than double because flow shearing stress will increase somewhat from the laminar value and Reynolds number will double, w,w 6

> 0.00183 in

%b Rey

=

max WESTINGHOUSE CLASS 3 Water used in the cold test described later had a dynamic viscosity

.at is more than cited above by a factor of two and a half to th.ee.

Thus, t.e maximum flow will have a laminar Reynolds numoer even on an incline simulating the 30-feet radius and film thickness will be 40 percent.arger than found above. 0.013 inch on the side wall and 0.026 inch on the inclined surface.

The maximum representative flows for a four-feet width of cold test surf ace are 2.1 gal / min on a vertical surface (0.0737 lbm/ft sec x 60 s/ min x 4 it/8.34 lbm/ gal) and 4.2 gal / min on an inclined surface.

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WESTINGHOUSE CLASS 3 i

1 3.

Test Apparatus The test surface is a flat, hot rolled steel sheet, eight feet long by four feet wide and one eighth of an inch thick, it is fastened on a sheet of half-inch plywood supported by three eight feet long pieces of 2 x 6 lumber with 2 x 6 pieces across the ends to complete the frame. The frame pivots on a one-inch pipe supoorted by a cross braced triangular stand made from 2 x 6 lumber. The four and one half feet square base is mounted on truck casters. Figure i shows the assembly. A gutter from the PVC pipe is

(

fastened at the bottom edge of the plate.

l After preparation by sandblasting the surface with G-40 size steel shot, it was spray coated with[

a., b

[Nfter coating, the surface had a wet appearance only briefly. It dried very repidly. Curing requires humid conditions. The curing rate was increased by mist spraying the surface with water after it was thoroughly dry. The finish is a matte gray that, because of its asperities. could be expected to present a wide range of contact angles on the surface that would permit wetting with no further treatment.

Water flow was always supplied to the plate from a one-half-inch tube pointed at the plate about four inches from the top edge at the center.

Flow was regulated by a valve and measured with a variable area meter (Rotameter type).

Various flow spreading devices were tried because, while the surface was wettable the flow did not spread appreciably. They are:

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7 Figure 1 - Test plate of 4 ft x 8 ft x 1/8 in flat steel mounted on pivoting frame on test stand.

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• RM-15625

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WESTINGHOUSE CLASS 3 l

1)

Weirs with and without fillers to provide flow resistance and to

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keep dirt from blocking the opening next to the plate surface.

Two weirs are shown in the photograph. Figure 2.

In use flow.

is toward the upper right. The far edges are straight and spaced from the plate surface by thin metal strips or wire.

That opening, an orifice, meters water onto the surface. Where there is an oversupply a head of water builds up behind the edge, causing a lateral flow to areas that are undersupplied.

The rear section has wide openings to permit inflow. Solid parts slope downstream so that water will be deflected toward the plate, not away and over the weir. The weir in the background is one-inch long and one quarter of an inch high.

The one in the foreground is two inches by one half inch. A third weir. shown in Figure 3 was constructed and tested. Itis also two inches by one half inch, but the upstream edge next to the plate has an approximately one-eighth-inch high dam that also serves to spread the flow laterally.

2)

Curtains of flexible, lightweight material laying on plate surface.

The upstream edge is held above the surface to permit water to flow under the material. Flow fills the cavity under the curtain.

'[

The head of water lifts the downstream edge which throttles flow. It is in effect a self adjusting orifice weir. Where there is greater flow the cavity fills higher and water flows laterally to areas with less flow. A number of materials were tried, two thicknesses of rubber sheet, cork. polyethylene sheet. 0.001-inch-thick stamiess steel shim stock. 0.001-inch-and 0.010-inch-thick mylar. 0.005-and 0.015-inch-thick lead sheet, d

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Figure 2 - Brass weirs shown from the upstream side. Open mesh cloth (cheesecloth) filler that was used is also shown. The downstream straight edge is spaced from the surface to create a throttling orifice.

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L Figure 3 - Weir. two inches long by one half inch high. Upstream opening is away from plate surface, creating an upstream dam.

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Woven screen laying flat on the surface. ~he screen wire acts series of dams and orifices distributea down the plate.

as e Even though there is lateral resistance to i.aw the repeated throttling does cause spreading. Aluminum wire window screen was used.

i The weirs and screen needed to be held down on the plate surface.

An aluminum angle was supported over the surface approximately six inches from the water supply tube. Eleven screws through threaded holes in it permitted pressure to be applied to the top of weirs. The arrangement can be seen in Figure 1.

When used on the containment. all parts of which have curvature, it is expected that weirs. curtains, screens etc. could be held tightly to the surface by spring loading the ends in tension and fastening to welded-on lugs.

i WESTINGHOUSE CLASS 3 4.

ReSults With water flowing from the one-half-inch tube onto the painted surface it did wet and rewet after being dried. With flows of one and two gal / min, most of the flow was in a twelve-inch-wide path down the eight feet of length, even when the whole surface had been wetted initially. At the higher flow rate the film was slightly wavy. These same results were obtained with the plate at an eleven-degree inclination to the horizontal and when it was nearly vertical. Rivulet formation did not occur. Figure 4 is a photograph of the film flow.

Testing was done with the smaller weir and using narrow shim stock spacers between its edge and the plate. The weir alone did not promote lateral spreading of the water flow well enough to form a film across the entire four feet width of the plate. When a sparse fill of cheesecloth was placed inside the weir and 0.015-inch shims were used, the flow resistance dammed the water and it spread well laterally for a 0.5 gal / min flow. At high flows the maximum water level near the supply point flooded over the one quarter-inch-high weir and further spreading of a film stopped.

Cotton string, cotton tape. jute, sisal, and plain cotton were tried as fills. Since they wedged between the upper part of the weir and the plate, their flow resistance was too great and the weir readily overflowed. Shim strips both thicker and thinner than 0.015 inch were tried and produced poorer results. Again, results at an eleven-degree inclination and near vertical were similar. Figure 5 shows the plate with a moderate film flow, about one gal / min. The entire width is l

wetted but there is flooding over the cheesecloth filled small weir near the middle.

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L -

WESTINGHOUSE CLASS 3 The larger weir. two inches by one-half-inch high did not overfiow at high flow rates. It worked well to cover the whole surface with a film up to 3 gal / min with a cheesecloth fill and up to 3.5 gal / min with a fill of stainless steel wool rolled into a rope. It was also tested with a one-eighth-inch diameter wire (solder) inside near the upstream edge, it worked very well at 4 gal / min and higher because it dammed the flow behind the wire in addition to spreading it with the weir's orifice. This led to the construction of the third weir with an integral dam.

The two inch by one-half-inch high weir with an approximately one-eighth-inch high dam at the upstream edge worked very well for a large range of flows from one to over six gal / min. No internal fill was used. Wire spacers. 0.017-inch diameter were wound on the weir. Figure 6 shows the high flow condition. Waves are apparent on the film surface.

Curtain performance was affected by curtain weight and stiffness. All 1

but the heaviest or stiffest worked to spread a water film. Thin stainless steel shim stock. 0.001-inch thick by six inches was the most successful in wetting the four feet of width. It was fastened at a shallow angle. The cork sheet shown in Figure 7 also produced a satisfactory film coverage.

The screen alone, as shown in Figure 8. where a one foot long piece is laying on the test plate, did not spread a film as well as the other devices.

However. a successful combination was a one and one-half-inch wide strip placed under the weir in place of shim stock spacers. It wet the four feet of width using the small weir.

R Early in the testing a wetting agent. Joy detergent, was added to water. It improved the wetting and film spreading appreciably. Waves disappeared when it was used.

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i WESTINGHOUSE CLASS 3 5.

Conclusions 1.

The j wets readily.

0-M 2.

A broad film does not form on the plate from water added at a point.

3.

Submerged weirs in combination with a shallow dam upstream most readily can be used to distribute a film from a point source.

4 Open mesh, like cheesecloth or rope from stainless steel wool, assists weir operation and can prevent blockage by dirt.

5.

Curtains can be designed to distribute water films satisfactorily on inclined surfaces. They may be adaptable to vertical surfaces as well.

6.

Screen alone does not distribute films as'well as other devices because of lateral flow resistance.

7.

Results were similar for the plate inclined only eleven degrees from horizontal and for it vertical.

8.

Surfactants assist spreading of uniform water films and hasten wetting of dry surface.

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WESTINGHOUSE CLASS 3 i

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6.

References l

f 1.

W. A. Stewart. " Natural Convection Cooling of AP-600 Containment."

l Westinghouse R&D Report 87-8J0-PASIV-R1 (April 1987).

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I 2.

E. R. G. Eckert and R. M. Drake, Jr.. Heat and Mass Transfer. 2nd Ed..

I 1

McGraw Hill Book Co.. New York,1959, pp. 334-338. 500.

3.

W. H. McAdams. Heat Transmission. 3rd Ed.. McGraw-Hill Book Co.. - New York.1954, pp. 329-336.

WESTINGHOUSE CLASS 3

.i 7.

Nomenclature G

Mass flow rate per unit plate width (Ibm /ft-s).

2 Acceleration due to gravity (ft/s ),

g Rey Reynolds number based on film thickness (dimensionless).

Average velocity in film flow (ft/s).

um 6

Film thickness (ft).

8 Angle of inclination (*).

p Dynamic viscosity (Ib/ft-s).

3 p

Density (ibm /ft ).

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