ML20125D621

Nonproprietary AP600 Passive RHR HX Test Final Rept

ML20125D621
Person / Time
Site:	05200003
Issue date:	12/15/1992
From:	WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19303F098	List: ML20125D612 ML20125D617 ML20125D621 ML20125D632
References
WCAP-13573, NUDOCS 9212150330
Download: ML20125D621 (91)

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WESTINGHOUSE CLASS 3 WCAP-13573 WESTINGHOUSE PROPRIETARY CLAS, 2 VERSION EXISTS AS WCAP-12980 AP600 PASSIVE RESIDUAL HEAT REMOVAL HEAT EXCHANGER TEST FINAL REPORT ED (C) WESTINGHOUSE ELECTRIC CORPORATION 19.9.2 A krense is reserved to the U.S. Govemment under contract oE4CO3 90SFt8495, O WESTINGHOUSE PROPRIETARY CLASS 2 TNs document contans informaton propnetary to Wesbnghouse Ekctf: Corporanon; a is admrtted in confidence and is to be used sowy for the purpose for wNch it is fumished and retumed upon request. This document and such informabon is not to be reproduced, transmitted, declosed or .

used othermse in wtiole or in part without authonzaton of Wesenghouse Electne Corporabon. Energy Systems Business Unit, sub iect to the legends contained hereof.

GOVERNMENT LIMITED RIGHTS:

(A) These data are submitted with hmited nghts under Govemment Contract No. DE-ACO3 90SF18495. These data may be reproduced and used by the Govemment with the express limitabon that they will not, without wntten permissaon of the Contractor, be used for purposes of manufacturer nor dsclosed outssde the Govemment; except that the Govemment may dsclose these data outsu% the Govemment for the following purposes. if any, provided that the Govemment makes such dsclosure sutgect to prohibrbon egenst further use and dtsdosure:

(1) TNs *propnetary data' may be cisdosed for evaluabon purposes under the restncbons above.

(II) The 'propnetary data' rnay be dsetosed to the Electnc Power Researth inetute (EPRI), electne uthty representatms and their drect consultanta, excludng droct commercial compettors, and the DOE Nabonal Laboratones under the proNtxtons and 13stncbons above.

(B) TNs notice shall be marked on any reproduccon of these data,in whole or in pa1 Q WECTINGHOUSE CLASS 3 (NON PROPRIETARY)

EPRI CONFIDENTIAUOBLIGATION NOTICES:

AOTICE: 1E 20 3 04 0s 0 - CATEGORY; A EB DC OoOE OF 0 0 DOE CONTRACT DELIVERABLES (DELIVERED DATA) l Subrect to e;scified excepbons, disclosure of this data is restncted unt! September 30,1995 or Desagn Certfcabon under DOE contract DE AC03-1 90SF t 8495, whichever is later.

Westinghouse Electric Corporation Energy Systems Business Unit Nuclear And Advanced Technology Division P.O. Box 355 Pittsburgh, Pennsylvania 15230 l

l l @ 1992 Westinghouse Electric Corporation l All Rights Reserved l

WESTINGHOUSE CLASS 3 TABLE OF CONTENTS ,

Section Title 1.0 ABSTRACT

2.0 INTRODUCTION

3.0 TEST OBJECTIVES 4.0 TEST CONFIGURATION 4-1 Description of the Test Facility 42 Main Test Characteristics & Parameters 43 Detailed Description of the Test Facility 4-4 ' instrumentation 441 Description 4-4-2 Calibration & Error Analysis 45 Test Procedure 5.0 TEST MATRIX AND DESCRIPTION 6.0 DATA REDUCTION METHOD 7.0 TEST RESULTS 7-1 Configuration Tests 7-2 Plume Tests 7-3 ' Steady State Tests 74 Transient Tests 7-S Uncovery Tests

8.0 CONCLUSION

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9.0 REFERENCES

t 00609-1:1D/101091 i

WESTINGHOUSE CLASE 3 l

1.0 ABSTRACT

~ A second series of experiments were performed in the AP600 Passive Residual Heat Removal (PRHR) test facility to broaden the existing database and to examine different possible design configurations. The experiments showed that the outside tube heat transfer was insensitive to proposed PRHR design changes. The models/

correlations developed from this series of experiments will therefore apply to the new PRHR design with multi rows of tubes which are separated by at least two feet between each row, The experiments performed in the second series covered the entire range cf fc<ced and natural circulation conditions so they will encompass the evaluated range of transient conditions expected in the AP600 Accident analysis. Experiments were also

• performed to examine boildown of the IWRST and its impact on PRHR performance.

The data from these experiments will support the AP600 PRHR design and will be used to assess the PRHR performance.

D0609-1:10n01091 1-1

_. ____________________1_. _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _

WESTINGHOUSE Ct. ASS 3 l

2.0 INTRODUCTION

The AP600 reactor is a pressurized water reactor being designed to utilize natural circulation heat exchangers as the safety grade means of removing core decay heat and sensible heat following certain design basis events. These passive residual heat removal (PRHR) heat exchangers remove core decay heat to mitigate non40CA events and are actuated on either a low steam generator secondary side water level followed by the failure of the non-safety grade startup feedwater system to operate; a low wide range SG water level; or on first stage Automatic Depressurization System (ADS) actuation. In the AP600 the PRHR heat exchanger replaces tha safety grade euxiliary feedwater system used in current operating planti today.

The PRHR heat exchangers transfer heat from the reactor scolant system to the containment by heating and boiling the water in the in-containment refueling water storage tank (IRWST). The steam produced transfers heat to the atmosphere by condensing on the ins;de of the containment shell. Condensation is assisted by the Passive Centainment Cooling System (PCCS). The condensate is collected by gutters on the containment shell and is returned to the IRWST. Therefore, the PRHR heat exchanger,in conjunction with the PCCS provides a heat sink for an indefinite amount of time.

As shown in Figure 2-1, the PRHR heat exchangers receive hot reactor coolant from the RCS pressurizer surge line and discharge to the steam generator channel head.

The natural circulation PRHR flow is developed from the density difference of the cold water in the PRHR tubes above the reactor core and the hot water in the inlet line to the heat exchangers. However,if PRHR flow is actuated with the reactor coolant pumps (RCPs) operating, the PRHR flow will be greater due to the larger pressure differential between the PRHR inlet and outlet connections to the RCS caused by the higher RCS flows. When the RCPs are operating, the flow rate through the PRHR heat exchanger is expected to be approximately three to five times higher than the flow rate that is expected during natural circulation flow.

The PRHR heat exchanger actually contains rows of vertical tubes headered at the top and bottom. The heat exchangers are distributed throughout the IRWST to maximize the capabilities of the IRWST as a heat sink and to delav !acalized boiling of the pool as long as possible. While it is not a safety concern,it is beneficial to delay IRW5Y boiling so that following spurious or inadvertent actuation of PRHR, there exists sufficient time to allow the operator to align secondary side heat removal systems and terminate PRHR before steam is released to the conta:nT.ent.

l 00609 1:10'101091 2-1

WESTINGHOUSE CLASS 3 The PRHR heat exchanger is utilized during many design basis events and is especially important in mitigating non LOCA events such as loss of normal feedwater and feedwater line break. To properly model the PRHR heat exchanger performance in the computer code analysis of these events,it was determined that prototypical testing of heat exchanger performance would be of substantial benefit. In particular, the testing was intended to provide information regarding pool boiling heat transfer regimes and the effect of voiding in the pool during heat exchanger operation over the range of conditions which could occur during design basis events.

Tests were performed that characterized the thermal performance of the PRHR heat exchanger and the mixing characteristics of the IRWST during the AP600 Conceptual Design Program (Phase 1). The results of the Phase I tests as described in Reference 1 covered a limited range of expected PRHR operating conditions and parameters.

Furthermore, these tests were designed and conducted to model the previous PRHR heat exchanger configuration. The previous configuration consisted of sirsingle rows of 75 tubes each distributed throughout the IRWST. The tubes were '18 feet long and were placed 4 feet below the IRWST water level.

This report describes the tests performed during the AP600 Design and Design Certification Program (Phase ll). The results of the Phase 11 tests covered the full range of PRHP operating conditions and parameters. Furthermore, tests were conducted which verified that the results of these tests are directly applicable to various PRHR heat exchanger configurations which utilize vertical heat exchanger tubes.

i 00609 1:1D'101091 2-3

WESTINGHOUSE CLASS 3 3.0 TEST OBJECTIVES The primary objective of the PRHR Heat Exchanger Test is to verify the thermal performance of the PRHR heat exchanger. This objective is achieved by testing heat exchanger tubes over the range of prototypic plant conditions and flow rates. A range of tube flow rates that correspond to the expected range of PRHR flow rates are tested. Inlet temperatures are varied from the maximum expected PRHR inlet temperature down to the minimum RCS temperature that the PRHR would be required to operate. From the test data, a design heat transfer' correlation will be developed for the computer codes that will be used to analyze the performance of the PRHR heat exchanger.

Secondary objectives of the test are:

Determine the mixing characteristics of the IRWST.

Determine the minimum time required for significant steam release from the IRWST to containment.

Determine the applicability of the heat transfer correlation as well as the steaming and mixing characteristics developed from this test to various heat exchanger configurations.

Determine what effect the water level above the tubes has on steam release from the IRWST to containment.

Each PRHR heat exchanger consists of rows of vertical tubes headered at the top and bottom and placed at various locations throughout the IRWST. The configuration basis of the test is to model a number of tubes in the middle of a long row of tubes.

This test configuration models tubes that experience a restricted flow of pool water because of the effects of being located in the middle of a long row of tubes. By modeling the most restricted heat exchanger tubes, the test will then conservatively predict the overall heat transfer performance of the PRHR heat exchanger.

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l 006091:1Dn01091 .3-1

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WESTINGHOUSE CLASS 3 4.0 TEST CONFIGURATION 4.1

SUMMARY

DESCRIPTION OF THE TEST FACILITY The test section replicates at full scale and prototypic flow, pressure and temperature conditions, three heat exchanger tubes from passive residual heat removal (PRHR) heat exchangers which transfer AP600 primary system core decay heat to an in containment refueling water storage tank (IRWST). The prototype design heat exchangers have 450 of 0.75 inch outside diameter,0.065 in, thick wall, type 304 stainless steel vertical tubes, each 20 feet long, connected to inlet (top) and outlet (bottom) headers on 1.5 inch centers. For tubes in the central part of the long array of tubes coolant flow to and upward along the tubes generated by_ buoyant forces is the most restricted. To sorne degree, these tubes are expected to have less thermal conductance to the heat sink. In the test section this effect is simulated by providing parallel, vertical baffle walls between the large pool that exists in the IRWST and the location of the three vertical heat exchanger tubes. The walls impose a two dimensional flow symmetry to and about each tube.

The IRWST is modeled in the test by a tall, circular tank filled with water having atmospheric pressure on its surface, which is nominally two feet above the top of the exchanger tubes. The tank has an outside diameter of four feet and a height of 32 feet which is filled to 22 feet above the bottom with water. The exchanger tubes are located near the tank wall on a radial plane,in an annulus between the tank wall and a partial cylinder baffle that is 4.5 inches, three tube pitches, inside the tank-wall. The geometry enforces two dimensional flow between planes of symmetry up to and beyond the exchanger tubes. A plan view of the arrangement is shown in Figure 4-1.

A separate test was conducted before designing the test section to provide insight into thermal and flow behavior. An electrical heating rod similar to a heat exchanger tube, but shorter, was placed between transparent baffles in a transparent tank of water that measured four feet by two feet and was 1.5 feet deep. Thermal stratification with nearly uniform temperatures on horizontal plancs was observed during transient heating. The testing showed how the convection pattern develops initially around the neater rod, and only after the tank bulk temperature approaches a boiling temperature, does the vigorous boiling around the heater rod produce strong buoyant currents in the tank which are able to reduce.

the stratification by mixing. Other observations were that significant steaming from i the free surface takes place only after the bulk temperature has approached the boiling point, that the length of baffle plates did not have an impact on the flow pattern, but that the distance between the heater rod and the back wall of the tank did have an effect on the " pumping action" of the heater rod. Because of this latter observation, provision was made for different locations of the back wallin the full scale test. The guides for a removable wall are shown in Figure 4-1. The back wall l simulates the IRWST wall and the distance between the tubes and it, the stand-off l

distance of the PRHR exchanger from the IRWST wall.

D0609-2:10/052991 4-1

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WESTINGHOUSE CLASS 3 To enable measurements of the PRHR heat exchanger performance at all conditions that the prototype could encounter, the test section tubes are supplied with water that is pressurized to as much as 2500 psig and heated to temperatures up to 650'F.

For that, there is a primary high pressure water circulation system using a canned motor pump and an electrical, temperature controlled water heater. An accumulator with regulated high pressure nitrogen over water provides the means for pressurization. Flow in each heat exchanger tube may be regulated by a manual valve at the outlet, while primary system flow can continue high enough for satisfactory pump and heater flow using a throttled recirculation or bypass pipe to the pump inlet. Figure 4 2 shows the test system piping and its components to scale.

The secondary side water is at prototype conditions as well during transient heat up and for saturated boiling at steady state for all the primary flow and temperature conditions.

Instrumentation is provided to measure heat transfer in the tubes. temperatures of water flow at various distances from the inlet inside two tubes, on the tube walls, and outside in the tank water throughout the baffled space as well as the larger tank volume. Pressures, primary flows and secondary steaming flow rates and water levels are also measured.

4.2 HEAT EXCHANGER CHARACTERISTICS, OPERATING PARAMETERS AND INSTRUMENTATION SUMM ARY The three heat exchanger tubes have the following characteristics:

Material: Type 304 stainless steel, ref, heat no. 477009 Dimensions: Nominal - 0.75 inch OD,0.065 inch wall thickness (See specifications ASTM A-269/213).

Measured - 0.748 inch OD,0.0665 inch wall thickness Nominal Length _18 feet Tube Spacing - 1.5 inch (centerline to centerline pitch)

Thermal Conductivity: Increasing from 9.8 Btu /hft'F at 271 F to 11.5 Btu /hft*F at 646 F The volume of water in the tank: 2182 gallons (727.3 gallons per tube) with water level 24 feet above bottom of the tank.

i DO609 2;1D/052991 4-3

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'I 00609-2:1D/052991 4-i-  % ,

WESTINGHOUSE CLASS 3 i

The test operating pararneters are: 1 Primary water temperature - 250' to 650' Primary water pressure - 50 to 2300 psig (above saturation pressere)

Single heat exchanger tube flow- 1 to 10 gallons / min.

Number of operating heat exchanger tubes- 1,2 or 3 )

Tank water level above top of tubes- 1 to 7 feet l Initial tank water level- 24 feet above bottom

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Tank temperature - ambient or less than 120'F to boiling at 212*F '

Baffles- back wall baffle may be behind tubes, partial baffle may be in front of tubes The instrumentation includes:

14 thermocouples inside each of two heat exchanger tubes (28 TC's) measuring primary water temperatures at the center of the tubes along their length.

12 thermocouples at the outer surface of each of two heat exchanger tubes (24 TC's) measuring temperatures along the length of the tubes 7 thermocouples measuring orimary water temperatures, one each at outlet of water heater, at inlet manifold to heat exchanger, before each of three flowmeters in outlet lines from three tubes, one in return line from heat exchanger near the pump and one at the bottom of the accumulator.

120 thermocouples at various elevations and locations in the modelIRWST (tank) 3 thermocouples on rotating traverses near the outer heat exchanger tube at three elevations inside the tank wall.

1 thermocouple at the top of the tank steam vent pipe.

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3 primary water flow orifice meters and differential pressure transducers (DP cells) in outlet line from each heat exchanger tube, 1 primary system pressure transducer before the inlet to the heat exchanger tubes.

1 primary system pump differential pressure trar sducer between inlet and outlet.

1 accumulator level differential pressure transducer.

1 tank level differential pressure transducer.

D0609 21D4)5299t 45 T 7 +- r- c-

WESTINGHOUSE CLASS 3 1 tank steam vent flow vortex flow meter.

- 4.3 DETAILED DESCRIPTION OF TEST FACILITY 4.3.1 Test Heat Exchanner The test heat exchanger includes the three heat exchanger tubes running vertically through a baffled section of the modelIRWST. The heat exchanger tubes, the tank, the baffle and internal supports are all fabricated from type 304 stainless steel. The tubes have nominal dimensions of 0.75 inch outside diameter, with a 0.065 inch thick.

wall and are eighteen feet and two inches long. The inlet lines are joineo to a carbon steel, high pressure, one and one half inch supply pipe and are 3/4 inch stainless steel tubing and swage type compression fittings outsic e the tank. They pass through an eight inch blind flange and fittings on a fabricated schedule 40 -

stainless steel flange welded to the tank 20 feet from the bottom of the tank. As shown in Figure 4-2,the center tube is at 20 feet but the inlet tube to the heat exchanger tube nearest the tank wall is two inches below that and the inlet tube to the heat exchanger tube nearest the baffle is two inches above. i'he inlet lines turn down in high pressure elbow connectors and, for the two outer tubes, join tees with 3/4 inch pipe threads which hold connectors for thermocouples from inside the tubes. All three supply lines are connected to the heat exchanger tubes below that, eight inches below the middle tube's elbow.

The three tubes are held by four stainless steel spacers, located five feet apart, which also slide on a 3g inch ~ diameter support tube for thermocouple leads. Except for the second support from the top, the spacers are tack welded to the middle heat exchanger tube. The second one is welded to the support tube. Differential thermal expansion is accommodated by the supports. They offer little flow resistance, being only 0.062 inches thick, but 1.5 inches high. The small support tube for leads is at the tank wall, two and one half inches before the line of tubes on the inlet side of the baffled tank water space.

Twenty inches from the bottom of the tank, the two outer heat exchanger tubes are fastened to tees with 3/4 inch pipe threads helding connectors for thermocouples from inside the tubes similar to the top.Below that all three exchanger tubes are connected to 0.75 inch diameter outlet tubes that pass through bellows fastened to an oval ten inch by thirteen and one half inch by one half inch thick blind flange at the bottom of the tank. The middle outlet tube is bent to offset it two and five-eights inches to provide room for the one and one-half iriches diameter, five inches long bellows. The bellows can accommodate two inches of thermal expansion.

The stainless steel tank itself is round,48 inches outaoe diameter with a one quarter inch thick wall. The tank is 32 feet high Figure 4-3 is a typical cross section view of

the tank, heat exchanger tubes,baHie location and construction and position of thermocouples in the tank water at numercus elevations. The baffie is 30 feet high, 00609-2

1om52991 4-6

WESTINGHOUSE CLASS 3 within two feet of the top. It is formed from four sections of one quarter inch thick stainless steel,89.875 inch high formed to an outside diameter of 38.5 inches over a 240 degree sector and having a three inch wide flange at each edge. The sections are held by bolting through one inch outside diameter tubes, four and one half inches long, eight or ten per section, and the tank wall, as shown in Figure 4-3. The "bacK wall"at the end of the baffle is gasketed and bolted to the baffle and, with a clamp, to the tank wall. Two inch angle is used at the ends of the baffle for additional support and to hold the baffle round. All bolts are seal welded to the tank after assembly.

- Pairs of one-half inch square bars, one quarter c,f an inch apart, are welded to the tank wall and the baffle opposite. One set is 11.85 inches behind the exchanger tubes and another is 17.77 inches behind,while the back wallis 23.69 inches behind at the average radius. The sets of bars serve as guides for inserting 0.050 inch thick stainless steel strips,30 feet high, to block flow at various distances from the tubes to simulate various stand off distances of the heat exchanger from the IRW5'l walls.

Additional guides are located 11.85 inches and 23.69 inches in front of the tubes.

These hold similar strips that are held eight inches from the bottom of the tank and

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L at the top are 22 feet from the bottom or two feet below the tank water level. They permitinvestigation of the impact of such a baffle on exchanger performance, flow and mixing in the tank.

The tank contains four viewing ports, three to observe boiling on the heat exchanger tubes and one to observe the water line behavior. They are Pyrex and l Sodaline glass, approximately six inches clear on standard 6 inch,150 lb. class, l flanges. They are rated for 150 psig, more than needed. Figure 4-3 shows their l locations on the tank. Another one is located on the tank cover plate, near the edge, i above the row of heat exchanger tubes. The tank cover is 54 inches in diameter,3/8 l inch thick on a gasketed flange. As shown in Figure 4-3, a moisture separator, l formed from three plates, draining at the tank wall,is located in front of a four inch l diameter steam vent pipe. The pipe is reduced to three inches before a vortex type i steam flow meter.

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There are many dram and fill lines cor$nected to the tank. Most of the drain lines are two inch standard steel pipe while fill lines are normally one and one-half inch pipes.

The ones that are useJ are shown on Figure 4-3. Not shown is that there is provision for a tank circulation pump between isolation valve IV-6 (inlet) and valve IV 5 l (delivery). Instead heated makeup water, supplied from a 27.5 kW water heater, l

usually with a temperature around 130 F,is led from the laboratory through valve IV 5 and into the tank at the top of the heat exchanger. Since makeup water is i required after the tank water is above 200 F, when steaming accounts for most of the heat transferred, the warmed but still relatively cooler water sinks through the tank and mixes.

i 00609-2:1oo5299 4-7 i

WESTINGHOUSE CLASS 3

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00609 2.10052991 4-9

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WESTINGHOUSE CLASS 3 i

The IRWST test tank is shown in the photograph, Figure 4 4. It is covered with two inches of thermalinsulation over the sides, bottom and cover except at the viewing and thermocouple ports and vertical channels for thermocouple leads. The channels i are formed by three and one half inch wide stainless sheet metal tack welded to the )

outside of the tank. There are four three inch wide channels in front of thermo-  !

couple sets at "E", "H", "J", and "K" and one six inches wide in front of sets "F" and "G" (see Figure 4 3). Figure 4 4 also shows the work platforms provided at elevations of ten, twenty and thirty feet above the foundation (7,17 and 27 feet above bottom of 32 feet tall tank). The first two platforms are 41 inches wide and cover two 60 degree segments of a hexagonal plan around the tank. The top has a full hexagonal set of 36 inches wide platforms. Ladders, alternately placed and safety caged above ten feet, connect the platforms. Checkered plate flooring is used some places, rectangular bar grating in others. The platforms are supported from stainless steel bars, six inches wide by 5/16 inch thick and six feet long welded vertically on edges to the tank. Support legs for the tank are four, eight inches square, H beams,each nine feet tall, welded to the tank wall.

4.3.2 Hinh Pressure Primary System The principal components of the primary system are a high pressure circulating pump, an electrical heater, a high pressure accumulator, circuit fill, drain and control valves and protection for the fired high pressure system.

4.3.2.1 Circulation Pump The pump is a two stage high pressure 50 gallons per minute (design) canned motor, 3450 RPM, unit manufactured by the Chempump Division of the Crane Company in Warrington, Pennsylvania (Model GHDT 20K). The characteristic of its 8.375 inch diameter impeller is 588 feet of head at zero flow, declining linearly to 556 feet at 50 gpm, and non linearly to 531 feet at 80 gpm. The net positive suction head (NPSH) varies from approximately four feet to fourteen feet in this range. The pump is rated at 20 horsepower,2500 psig and below and 650'F and below. The motor is cooled by auxiliary cooling water. Internal winding sensors trip the pump off when excessive temperatures are reached. High primary water temperatures and high flows (and pump power) did cause trips occasionally during operation. The pump is shown on the left in the photograph, Figure 4 5. The pump's net efficiency is near 25%. Inlet piping is 2.5 inches and outlet piping is 1.5 inches. Thermal distortion during operation, particularly start up and shut down did lead to smallleakage from the high pressure system. An orifice and filter or strainer are used in the pump discharge piping. The orifice.which has a 0.688 inch diameter, provides flow resistance so that there is enough pressure drop to total flows to both the test flow loop and (if used) the parallel by pass loop so that the pump operates in a desirable head and flow regime (Sne Figure 4 2).

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WESTINGHOUSE CLASS 3

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5 i 4.3.2.2 Electrical Heater The primary water heater is a specially designed and manuf actured unit rated at a total power of 350 kW at 480 volts and three phase supply, a design pressure of 2500 psig and a peak service water teminerature of 650*F. It was and caps,eight inch 1500 lb. flanges (SA 182F11 steel) holding 15 Incaloy sheath heating elementsin each section. Each element is 96 inches long,0.475 inch diameter producing 48 watts per square inch of surface. The two sections are joined at the flanged ends by a cross over pipe. The inlet (bottom) and outlet (top) flanges are four inch,1500 lb., and couple with two and one half inch schedule 80 system inlet and outlet pipes. The unit is shown in Figure 4 6. All parts are wellinsulated.

Two type K (thromel alumel) thermocouples are installed in each heating section.

They are used with a temperature controller (Watlow Series 808) to regulate power from a 450 ampere silicon controlled rectifier power controller. Since the line voltage supplied is 460 volts, maximum power is 321 kW. The power controlis in the cabinet in the foreground of Figure 4 6 and the supply circuit breaker is on the building wall (upper right).

4.3.2.3 Accumulator The accumulator is a tall vessel fabricated from twelve inch schedule 120 pipe (A 106-C steel) and caps having an overalllength of fourteen feet and ten inches.

The bottom of the accumulator is connected to the primary circulation system after the heater outlet by a two and one half inch schedule 80 pipe. A threaded pipe connection on the side at the top is connected to a regulated supply of nitrogen from an extra high pressure cylinder (5000 psig). The regulator can bleed gas from the accumulator if pressure rises above the set pressure, but not at a high rate. At the top of the accumulator, a one and one-half inch,1500 lb. flange connects to a relief valve which is usually set to vent automatically if pressure rises to above 2500 psig. There is an additional safety relief, a rupture disk which at the low temperature it experiences will burst at a prenure above 3000 psig. Since the blowdown can be very rapid for hot steam flashing f rom the primary system,the two saf ety devices vent into a fifty five gallon drum filled with water.

4.3.2.4 Pipinq and Valves Refer to Figure 4 2 for a diagram of piping. Primary system piping from control valve CV 4 to the heat exchanger inlet tubes and from the individual tube control valves CV 1, CV 2, and CV-3 is one and one-half inch schedule 80 steel pipe. The recirculation line, whose flow is controlled by valve CV 5 is the same up to the exchanger return line where it becomes two and one half inch pipe. The primary system may be filled by opening isolation valve IV-4 to vent air. Deionized water is used to fill the primary system through valves IV 1 and IV-2. The levelin the accumulator is adjusted during filling by venting through valve CV-6. This valve can 4-12 00609 2 ioms2991

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WESTINGHOUSE CLASS 3 be used also to lower system pressure during warming and expansion of the system water. The system may be drained through valves IV-1 and IV 3 and other valves on the pumo and accumulator.

4.4 INSTRUMENTATION instrumentation for the PRHR heat exchanger testing includes thermocouples to register temperature in and on the heat exchanger tubes,in the secondary side tank water and in primary heating and circulating system, pressure transducers for primary system pressure and flow through standard orifices anc water levels in the accumulator and tank, a flow meter for steam flow from the tank and a watt meter to register heater input power.

4.4.1 Thermocouples Two types of thermocouples are used, chromel-alumel double precision (type KK) ungrounded junction in 304 stainless steel sheaths with double precision extension wires for high fluid temperatures in the primary system and heat exchanger tubes and copper-constantan double precision (type TT) ungrounded junction in 304 stainless steel sheaths with double precision extension wires for low fluid temperatures in the secondary water tank.

The outer and middle heat exchanger tubes are instrumented with 0.032 inch sheath diameter thermocouples. There are fourteen thermocouples inside each tube, twelve of which are mounted on a 3/32 inch diameter support rod, and two are installed at each end of the tube, measuring the inlet and outiet fluid temperatures.

The thermocouples measuring the test tube fluid temperature are spaced 1.5 feet apart and are tied to the inside support rod, which is centered within the tube with 1/16 inch stainless steel strips 1/2 inch wide and 5/8 inch long that are tack welded to the 3/32 inch rod at 1.5 foot intervals. The rod protrudes through and 6 welded to the 90o elbow at the top of the tube.

The verticallocations of these thermotouples are tabulated in Table 41. Seven thermocouples are led to the top of each tube and seven are led to the bottom. At each end they pass through special high pressure seals that are semi elastic disks, with holes for the thermocouples, compressed between pressure plates having similar holes and keyed to the body of a fitting whose screw cap provides the compression. Each fitting is pipe threaded into tees at the ends of the heat exchanger tubes. Thermocouple sheaths pass through tank water to tubes, held by swage type tube connectors,into which they are soldered. The tube connectors are threaded into circular plates which are part of blind flanges fitted into eight inch diameter flanges on the tank, and which are flush with the inside radius of the tank.

These are located fourteen inches from the bottom of the tank and nineteen feet from the bottom of the tenk.

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l D0609-2:10os2991 4-14

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WESTINGHOUSE CLASS 3 l l

Thermocouples are also mounted near the outside surface of the tubes in machined i grooves. The transverse grooves are 0.40 inch long,0.025 inch deep and are spaced 1.5 feet apart. In order to assure that the tube integrity is not jeopardized at the test conditions, samples of the tube, with machined grooves, were pressurized and ruptured. In addition, a finite element analysis of the grooved tube was performed in order to determine whether the grooves would limit the primary fluid operating pressure. No effect of the groove on the tube strength was noticed. The tip of an 0.020 inch sheathed thermocouple was inserted into the 0.025 inch x 0.025 inch groove and was brazed over with silver solder (melting temperature near 1000*C) thus restoring the tube surface to its original configuration in order not to impact the boiling regime on the tube surface. The sheathed thermocouples were mounted closer to the outside tube surface rather than to the bottom of the groove. There are twelve thermocouples on each tube, spaced 1.5 feet apart, at the elevations tabulated in Table 41. Their leads were run out to a 3/8 inch diameter support tube which is at the tank wall, two and one half inches in front of the line of tubes.

Thermocouple leads then run half to the top and half to the bottom of the exchanger where they are led through tubes in which they are soldered, held by fittings,in two more eight inch flat blind flanges on the tank wall next to the pair for tube internal thermocouples.

To register water temperatures in the tank there are 120 copper constantan,0.032 inch diameter stainless steel sheath thermocouples. They are located at the elevations shown in Table 4 2 and the lettered locations marked on Figure 4 3. The thermocouples at locations "C" and"D",in the central part of the tank are f astened to two 1/4 inch stainless steel rods, thirty feet long, booked onto U bolts welded to the bottom of the tank and fastened to a two inch angle spanning the uppermost baffle flange at the top. The thermocouples, eleven at each location, are led out of the tank through 1/4 inch tubes held by swage type tube connectors screwed into 1/4 inch pipe half couplings welded into the vessel 23 inches below the top. All the other thermocouples,those at locations "E", "F" "G", "H", "J" and "K" are held in place, two and one quarter inches inside the tank wall by 1/8 inch tube stubs.

Sheaths are soldered into the tubes. Each tube is held by a swage type tube connector in a 1/8 inch pipe half coupling welded into the vessel at the appropriate angle and elevation, a total of 98 locations. Rubbe booted connectors for extension wires are all outside the tank.

All extensions are led down or up thermocouple lead channels to a cable tray just below the first work platform and from there into the laboratory building.

Three additional thermocouples,1/16 inch sheath diameter are used to traverse tank water temperatures very near the outer heat exchanger tube at three elevations, just below the lower two viewing ports and just above the third one. Figure 4 7 shows the installation of these rotating traverse thermocouples and the indicator for ma iually traversing. Data channels are listed in Table 4 3.

D0009-2I1DC52991 4 15

WESTINGHOUSE CLASS 3 TABLE 4 2 THERMOCOUPLE LOCATIONS IN SECONDARY SIDE TANK OF PRHR HEAT EXCHANGER Position Arimuthal Location C 90',4 in, outside baffle in line with tubes D Centerof tank E 74*, inside baffle,5.0 in, behind tubes  !

F 98',inside baffle,3.0 in. in front of tubes G 106',inside baffle,6.0 in in front of tubes H 123*,inside baffle,12.4 in. in front of tubes J 205',inside baffle,43.2 in. in front of tubes K 325*,inside tank,2.25 in. from wall,20.6 in. from baffle D0609 2.10052991 4-17 v

l WESTINGHOUSE CLASS 3 Thermocouples are also mounted near the outside surface of the tubes in machined grooves. The transverse grooves are 0.40 inch long,0.025 inch deep and are spaced 1.5 feet apart. In order to assure that the tube integrity is not jeopardized at the test conditions, samples of the tube,with machined grooves, were pressurized and ruptured. In addition, a finite element analysis of the grooved tube was performed in order to determine whether the grooves would limit the primary fluid operating pressure. No effect of the groove on the tube strength was noticed. The tip of an 0.020 inch sheathed thermocouple was inserted into the 0.025 inch x 0.025 inch groove and was brazed over with silver solder (melting temperature near 1000'C) thus restoring the tube surface to its original configuration in order not to impact the boiling regime on the tube surface. The sheathed thermocouples were mounted closer to the outside tube surface rather than to the bottom of the groove. There are twelve thermocouples on each tube, spaced 1.5 feet apart, at the elevations tabulated in Table 4-1. Their leads were run out to a 3/8 inch diameter support tube which is at the tank wall, two and one half inches in front of the line of tubes.

Thermocouple leads then run half to the top and half to the bottom of the exchanger where they are led through tubes in which they are soldered, held by fittings,in two more eight inch flat blind flanges on the tank wall next to the pair for tube internal thermocouples.

To register water temperatures in the tank there are 120 copper constantan,0.032 inch diameter stainless steel sheath thermocouples. They are located at the elevations shown in Table 4 2 and the lettered locations marked on Figure 4 3. The thermocouples at locations "C" and"D",in the central part of the tank are fastened to two 1/4 inch stainless steel rods, thirty feet long, hooked onto U bolts welded to the bottom of the tank and fastened to a two inch angle spanning the uppermost baffle flange at the top. The thermocouples, eleven at each location, are led out of the tank through 1/4 inch tubes held by swage type tube connectors screwed into 1/4 inch pipe half couplings welded into the vessel 23 inches below the top. All the other thermocouples,those at locations "E", "F" "G", "H", "J" and "K" are held in place, two and one quarter inches inside the tank wall by 1/8 inch tube stubs.

Sheaths are soldered into the tubes. Each tube is held by a swage type tube connector in a 1/8 inch pipe half coupling welded into the vessel at the appropriate angle and elevation, a total of 98 locations. Rubber booted connectors for extension wires are all outside the tank.

All extensions are led down or up thermocouple lead channels to a able tray just below the first work platform and from there into the laboratory building.

Three additional thermocouples,1/16 inch sheath diameter are used to traverse tank water temperatures very near the outer heat exchanger tube at three elevations, just below the lower two viewing ports and just above the third one. Figure 4 7 shows the installation of these rotating traverse thermocouples and the indicator for manually traversing. Data channels are listed in Table 4 3.

1 00609 2,10 o52991 4-15

1 WESTINGHOUSE CLASS 3 TABLE 41: THERMOCOUPLE LOCATIONS IN CENTER AND ON SURFACE OF PRhR HEAT EXCHANGER TU8ES Thermocouple No. & Channel Elevation from Outer Tube Middle Tube Outer Tube Middle Tube Bottom of Tank (in.) Fluid Fluid Surface Surface 236 14 28 230 13 27 221 40 52 212 12 26 203 39 51 194 11 25 185 38 50 176 10 24 167 37 49 158 9 23 149 36 48 140 8 22 131 35 47 122 7 21 113 34- 46 104 6 20 95 33 45 86 5 19 77 32 44 68 4 18 59 31 43 50- 3 17 41 30 42 32 2 16 23 29 41 12 1 15 00609-2:10 052991 4-16 I

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WESTINGHOUSE CLASS 3 TABLE 4 2 THERMOCOUPLE LOCATIONS IN SECONDARY SIDE TANK OF PRHR HEAT EXCHANGER Position Arimuthat Location ,

C 90',4 in. outside baffle in line with tubes D Center of tank E 74',inside baffle,5.0 in. behind tubes F 98*,inside baffle,3.0 in. in front of tubes G 106',inside baffle,6.0 in. in front of tubes H 123',inside baffle,12.4 in. in front of tubes -

J 205',inside baffle,43.2 in. in front of tubes K 325', inside tank,2.25 in, from wall,20.6 in. from baffle h

D0609 2.1D052991 4*17

WESTINGHOUSE CLASS 3 TABLE 4 2 THERMOCOUPLE LOCATIONS IN SECONDARY SIDE TANK OF PRHR HEAT EXCHANGER (continued)

Thermocouple No. & Channel I

Elevation from C D E F G H j K Bottom of Tank (in.)

336 63 74 93 112 131 150 161 172 l 312 62 73 92 111 130 149 160 171 l

228 61 72 91 110 129 148 159 170 275 60 71 90 109 128 147 158 169 257 89 108 127 146 239 59 70 88 107 126 145 157 168 221 87 106 125 144 203 58 69 86 105 124 143 156 167 185 85 104 123 142 167 57 68 84 103 122 141 155 166 149 83 102 121 140 131 56 67 82 101 120 139 154 165 113 81 100 119 138 95 55 66 80 99 118 137 153 164 77 79 98 117 136 59 54 65 78 97 116 135 152 163 41 - 77 96 115 134 .

23 53 64 76 95 114 133 151 162 5 75 94 113 132 00609-2:10 052991 4*18

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Dimensions in inches Figure 4-7: Rotating Thermocouple Traverses (3) 006094 1D952991 4 19

WESTINGHOUSE CLASS 3 4 Three additional thermocouples,1/16 inch sheath diameter are used to traverse tank water temperatures very near the outer heat exchanger tube at three elevations, )

just below the lower two viewing ports and just above the third one. Figure 4-7 l shows the installation of these rotating traverse thermocouples and the indicator for  !

manually traversing. Data channels are listed in Table 4 3. ,

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4.4.2 Flowmeters  ;

Flow in the outlet piping of each of the heat exchanger tubes was measured using a precision orifice mounted in a standard holder connected in line with 3/4 inch schedule 80 piping. For high flows, to 10 gallons per minute, the orifices used had bores of 0.540 inch. Another set, with a range of application of 0.3 to 0.9 gpm was substituted for low flow tests. Current loop output pressure transmitters,4 to 20 mA, were used as differential pressure transducers on each orifice meter. Their outputs, converted to 80 to 400 mV signals, were recorded. See Table 4 3.

A three inch diameter vorte: flowmeter in the tank steam outlet piping provides a measure of the vapor genera. tion rate. Its output similarly was recorded as a voltage signal.

4.4.3 Pressure and Level Gauces System pressure was measured using a pressure transmitter which functioned in the same way as those used for flow measurement except that its range was much larger.

Level for the accumulator was measured using a pressure transmitter,like those for tube flow, connected between the top and bottom of the accumulator. Level for the tank was also measured using the same model pressure transmitter. It measured level by the difference in pressure at the bottom of the tank and ambient. It could not be connected to the steam filled top of the tank because condensing filled the low pressure leg with liquid. The pressure transmitters all were rated for primary system maximum pressure,2500 psig. Their loc 6tions are shown in Figure 4 8.

4.4.4 Wattmeter A combination wattmeter and watt hour meter measures combined input power to two SCR controllers which supply power to the two sections of the 350 kW high pressure water heater. The rr.eter is for three phase, three wire circuits (delta) having 0-480 volts and 0 500 amperes. The watt meter range is 0-500 kW for an output signal of 0-10 volts that is recorded on channel 200. The watt-hour meter range is 0-500 kWh and above that it resets to zero, and it has a 0-10 volts output signal registered on channel 201. The meter is located inside the laboratory building. Voltage leads are connected to the power input wires in the heater control cabinet at the sae of the test heat exchanger. Current transducers are on two of the 00609-2 10os2991 4 20

WESTINGHOUSE CLASS 3 TABLE 4 3 '

ADDITIONAL INSTRUMENTATION OF PRHR HEAT EXCHANGER TEST Data Channel Thermocouples 173 Water in outer heat exchanger tube outlet.

174 Water in middle heat exchanger tube outlet.

175 Water in inner heat exchanger t"be outlet.

176 Water at bottom of accumulator.

177 Water at inlet to heat exchanger inlet manifold.

178 Steam venting from tank in vent pipe.

179 Water at heater outlet.

Level and Flowmeter Transducers (80 400 mV. range) 181 Primary system pressure.

182 Outer heat exchanger tube orifice flow meter pressure difference, FM 1, 183 Accumulator level, differential pressure.

184 Tank level, differential pressure.

185 Pump pressure rise, differential pressure.

187 Middle heat exchanger tube orifice flow meter pressure difference, FM 2, 188 inner heat exchanger tube orifice flow meter pressure difference,

• FM-3.

189 Tank steam vent vortex flow meter output.

Thermocouples 190 Lower traverse in tank water.

191 Middle traverse in tank water 192 Upper traverse in tank water, 193 Primary return flow from heat exchanger near pump Wattmeter (0-10 Volts) 200 Heater supply power (kW).

201- Heater supply energy (kWh).

00609 2:1D052991 4 21

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00609 2;1D05299: 4 22- I l-1-

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WEST 1NGHOUSE CLASS 3 input power leads in the heater control cabinet and they both have two wire connections to the meter.

4.4.5 Data Acquisition and Recordino All instrumentation is connected to a model 2240 John Fluke Mfg. Co. " Data Logger" utilizing a low level scanner with three pole low thermal emf reed relays-and a high performance A/D converter using dual slope integration over five line cycles (slow speed,3 readings per second) or one line cycle (fast speed,15 madir$9s per second). Accuracy is 0.01% of reading plus 0.008% of range. Resolution for either type K ort thermocouples is 0.1*F in the 32'F to 750 F range. Isothermal blocks are used and provide a maximum 0.1*F gradient between any terminals and 0.01'F reference junction stability. Digital data is transmitted for storage and retrieval to a personal computer with hard disk and for eventual recording on

" diskettes". The recorded information includes data and time of scan, channel number and tem,peratures ('F cr 'C) and voltages, as programmed in the " Data Logger" The data acquisition system is shown in Figure 4 9.-The " Data Logger" is rack mounted with its channelincreasing expander chassis. A video display terminal is used to observe data during testing.

4.5 TESTING PROCEUURES Prior to testing the following steps are followed:

Initial filling of the tank - Close isolation valves IV 5,6,7 and 9;open IV 8 to fill; monitor tank level, channel 184, until test level is achieved; close IV 8.

Filling and pressurizing the primary system - Open high point vent valve,IV 4; close accumulator vent valve, CV 6; verify that CV 1,2,3,4, and 5 are not closed; when water comes out at IV-4, close IV 4; monitor water level in the accumulator, channel 183, and fill to 50 inches; close fill valves IV 1 and 2; bleed air from all pressure transducers and the pump; set nitrogen pressure regulator, CV-7 to 200 psig + /-15 psig; turn on pump for two minutes, then stop pump; recheck accumulator level and open high point vent valve IV-4 to vent air from system; assure at least 45 + /-5 inches water is in accumulator; reset nitrogen pressure regulator to 500 + /-15 psig.

Primary system heat up Turn on pump and verify it's on; verify proper accumulator pressure and water level; set water temperature cov oller to 460'F; turn on water heater; monitor primary system temperature and pressure as it heats, channel 179 for heater outlet temperature and channel 180 for system pressure; start taking data at appropriate conditions; if test requires higher temperature, reset controller and raise accumulator pressure accordingly to prevent boiling using information from steam tables.

D0609-2.1 D 952991 4-23

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l D0609 210952991 4 24

WESTINGHOUSE CLASS 3 F

Before beginning a test, prerequisites are to be performed. These include the following.

1. Record test parameters including test ID number, number of flowing heat

exchantjer tunes, tube flowrote and inlet temperature.

2. Ched and verify any revision of procedure, that instruments to be used are calibrated, that all instrumentation is functioning, accumulator water level is 45 + /-5 inches and accumulator pressure is at least 500 + /-15 psig, and that secondary tank water level is as required.

3. Verify that pump is on and set control valves for active tubes. ,

4. Adjust CV 4 and CV 5 to produce required flow in primary circuits.

5. Balance tube flows to + / 0.3 gpm.

6 Name the data acquisition record output file with the test ID number.

During a test, the following instructions are followed for four types of tests:

A. Transient Tests

1. Set conditions required for the test identified.

2. Assure that tank levelis set to 24 ft. + .5 ft and that all tank thermocouples read < 120'F.

3. Open valve CV-4 and start Data Logger at one (1) minute intervals. '

4. At 20 minutes into test, set Data Logger at five (5) minute intervals.

5. Monitor system parameters until tank has reached bulk boiling. This is defined as when all thermocouples except Nos. 75,94,113 and 132 are 200

+ 5*F.

B. Steady State Tests

1. Set conditions required for the test identified.

2. Once steady state bulk boiling is attained, assure tank levelis 24 ft + .5 ft.

Take ten continuous sets of data. Steady state is defined as when all thermocouples except Nos. 75,94,113 and 132 are at 200 + 5*F, (Record the maximum primary inlet temperature for this test).

l D0609 2:1D952991 4 25

WESTINGHOUSE CLASS 3 5.0 TEST MATRIX AND DESCRIPTION The Test Matrix for both the Phase I tests (performed in 1989) and the Phase 11 tests (performed in 1990) are included in Table 5-1. The test matrix consists of five types of tests as specified below:

Transient Tests-These tests were performed to determine the tank mixing behavior for various combinations of tube flow rate and inlet temperature. Transient tests were also performed to develop a correlation for the free convection heat transfer mechanism that occurs when the tank is sub cooled.

Transient tests were performed by heating up the tank from ambient conditions to boiling with a fixed tube inlet temperature and tube flow rate. Data was initially recorded at short intervals (1 minute) for twenty minutes and then recorded at longer intervals (5 minutes) until the tank reached bulk boiling. Bulk boiling was defined as when all tank thermocouples at a level above the lowest tube primary side or wall thermocouple had readings of 212 + /- 5'F.

Steady-State Tests -These tests were performed to develop the PRHR heat exchanger heat transfer correlation. Typically the tank was heated to boiling by utilizing the pump, heater, and heat exchanger tubes. Once the tank bulk temperature was 212'F, the test was begun. A tank bulk temperature of 212*F was defined as when all tank thermocouples at a level above the lowest tube primary side or wall thermocouple had readings of 212 + /- 5'F.

After bulk boiling was achieved, the flow through the heat uchanger tubes was set by throttling the appropriate valves. The tank level was verified and makeup to the tank was provided if needed to re establish the correct tank level. Ten data scans were taken at each specified inlet temperature until the full range of inlet temperatures had been covered. The range of inlet temperatures for each test is from a maximum of 650'F to 250*F at 50' intervals. The maximum inlet temperature for each test varied depending on the total tube flow rate due to the limited capacity of the heater.

Plume Tests-The purpose of these tests was to determine characteristics of the - i water steam plume that exists around the heat exchanger tubes. These tests were conducted by heating the test tank up to boiling at a selected PRHR tube inlet temperature and flow rate. Once bulk boiling was achieved, the rotating thermocouples located at the three specified elevations were rotated to determine the physical dimensions of the plume at each elevation.

Configuration Tests-These tests were performed to confirm the applicability of the test results to the final PRHR physical configuration.

Configuration parameters tested included:

Distance of the heat exchanger to the IRWST wall D0609 3:10 052991 51 '

b

WESTINGHOUSE CLASS 3 Table 51 PRHR Heat Exchanger Test Matrix Phase i Tests Steady State Tests T_est Flow / Tube No. of Tubes Inlet Temperature 55-3 5gpm 3 425'F - 250'F 55 4 6gpm 3 425'F - 250'F

$5 5 7gpm 3 425'F - 250*F 55-5 9gpm 3 400*F - 250'F 55 5 10 gpm 3 400'F - 250*F Transient Tests Test Flow / Tube No. of Tubes Inlet Temperature TR-1 7gpm 3 417*F TR 4 9gpm 3 405*F TR-7 6gpm 3 420*F TR 11 6gpm 1 630'F Phase ll Tests Plume Tests Test ID # of Tubes Flow per tube inlet Temperature Comments P-01 (R) 3 3gpm Max- Rotate TC 0180*

P-02 (R) 1 3gpm 600*F Rotate TC 0180' P-03 3 6gpm - Max Rotate TC 0180' P-04 1 6gpm 600 F Rotate TC 0-180*

P-05 3 9gpm Max Rotate TC 0-180' P 06 1 9gpm 600*F Rotate TC 0-180 Notes: 1) (R) indicates video recording performed for portions of this test.

2) The configuration tests were run as both a transient test (heating the tank from ambient to bulk boiling), a steady state test (varying the inlet temperature from the maximum down to 250*F), and a plume l test.

D0609 3:1DC52991 5-3

y e --M-- -.,a--1 s> -*4 WESTINGHOUSE CLASS 3 Table 51 (cont.)

Steady State Tests Test ID # of Tubjts Flow per tube inlet Temperature Comments 5-01 3 9gpm Max. 250'F (1) 5 02 (R) 3 6gpm Max -250'F S 03 3 3gpm Max. 250'F '

S 04 (R) 3 0.3 gpm 650'F-250'F S 05 (R) 3 1gpm 650'F-250'F S 06 (R) 2 0.3 gpm Max.250'F S-07 (R) 1 9gpm Max.250*F S 08 1 6gpm 650'F 250*F S-09 1 3gpm 650*F-250'F -

S 10 1 0.3 gpm 650*F-250*F S 11 1 1gpm 650*F 250*F S-12 (R) 2 6gpm Max.-250*F S-13 (R) 2 3gpm Max. 250'F S-14 (R) 2 1gpm 650'F 250'F S-15(5) 3 1gpm Ma x.-2 50'F Notes: 1) The standard configuration consisted of the tubes 2 ft, from the back wall, no baffle, and a water level of 22 ft. This configuration was determined after completion of the configuration tests.

2) Tests 5 07 through 5-11 will be run using the middle tube.

3) Tests 5-12 through 5-14 will be run using the two outside tubes.

4) (R) indicates video recording performed for portions of this test.

5) Test 5-15 is a repeat of test S 05. It was performed after all other medium flow steady state tests had been completed.

Uncovery Tests Test ID 1 of Tubes Flow per tube Inlet Temperature Level j U 01_ 3 3gpm 500'F 100 %

i U 02 (R) 3 3gpm _ 500'F 75%

U-03 (R) 3 3gpm 500'F 50 %

' U-04 (R) 3 3gpm 500*F 25%

U-05 3 3gpm 500*F 0%

Note: 1) (R) indicates video recording performed for portions of this test.

j .- D0f 09-310052991 5 5-

WESTINGHOUSE CLASS 3 6.0 DATA REDUCTION AND ANALYSIS METHODS ,

This section will describe the methods used to reduce the test data from the phase I and ll experiments to calculate local and overall tube heat transfer performance of the PRHR exchanger.

Data was reduced to calculate the local and overall heat transfer performance of the PRHR heat exchanger. As described earlier, both steady-state and transient experiments were conducted. The steady state tests were performed for a series of tube flows and initial primary side temperatures and a constant tank temperature.

The transient tests had both a transient primary side temperature as well as a transient tank temperature. The transient tests were long transients (minutes, not seconds) such that a quasi-steady state approach could be used to interpret the test data. In addition, tests with tube bundle uncovery were also performed to simulate boil down of the IWRST.

Figure 61 shows a sketch of the instrumentation which is used to calculate the tube heat flux, overall heat transfer and outside heat transfer coefficient. The primary measurements included the tube flow rates, primary fluid axial temperature distribution, tube outside wall temperatures and the tank temperatures which were measured at severallocations and elevations within the tank.

The primary fluid axial temperature profile in the water tubes was measured at 1-1/2 ft increments using the thermocouples inside the tube. Care was used to not block large amounts of the tube flow area so thermocouples came in from both the top and bottom of the tube. The axial primary fluid thermocouples were used to calculate the wall heat flux by just converting the temperature data to enthalpy from the steam tables and then writing a steady state energy balance on the primary side fluid as:

q'* = ".L b (6-1)

, no, dx For improved accuracy, the primary fluid enthalpies were curve fitted to a second-order polynomial and the resulting curve differentiated to obtain the wall heat flux.

The use of the fitted enthalpies for the heat flux calculations, rather than temperatures reduces the uncertainty of averaging the specific heat over the 18 inch

' length in the test section. Specific heat variations can become significant at high primary side temperatures. Curve fitting the primary fluid enthalpies results in smoother calculated wall heat fluxes since the individual fluid enthalpy variations are minimized particularly when taking differences. Figure 6 2 shows a typical plot

-of the measured primary fluid enthalpies with the fitted expression. As the figure shows, the fit is excellent. Figure 6 3 shows the resulting wallinside heat flux 00609 3 toes 2991 61

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Figure 61: Instrumentation Locations and Layout to Calculate Local Tube Wall Heat Fluxes 006043:10 052991- 62

WESTINGHOUSE CLASS 3 calculated from the fit which again shows a smooth continuous curve at might be expected.

The use of Equation 61 assumes a steady state process. As explained above,while some of the tests were transient, the time period for the transient was much longer than the transient time of the primary system water as it flowed in the tubes such that use of Equation 61 is acceptable for these quasi steady state situations.

Using the calculated wall heat flux from the primary fluid enthalpies, the radial temperature distribution can next be calculated at each instrumented position. To calculate the inside wall temperature, an appropriate inside tube heat transfer correlation was determined based on the tube geometry, flow, and fluid properties.

The literature was reviewed and the correlation by Petukov-Popov0) was used to calculate the inside wall convection coefficient. The textbook by Kreith and Bohmm reviewed the different turbulent convection heat transfer coefficients and recommended Petukt,v Popov since it had less uncertainty than Dittus BoelterO) or other similar correlations. In addition, since large temperature gradients existed in the primary fluid, a viscosity correction was applied to both the Dittus Boelter and Petukor Popov correlations. The hydraulic diameter used was only the tube diameter since accounting fo,r the thermocouple leads overestimated the wetted parameter effect which would contribute to the frictional pressure drop but not the wall heat transfer ef fects. Using the inside wall heat flux from the enthalpy balance results in an inside wall temperature calculated as:

Twi(x) = Tpi(x) qwi(x)/hi(x) -(62) where the inside tube wall heat transfer coefficient, hi,is obtained from the correlations above. Once the inside wall temperature is calculated, the temperature drop across the tube wall can be calculated using the steady-state heat conduction solution for cylindrical coordinates. The calculated outside wall temperature becomes qwjx)Di (Do)

Two(x) = Twi(x) .- Ln Di where the tube wall conductivity, K(x),is a function of temperature, Direct measurements of the tube inside diameters, outside diameter and wall thickness were made and used in the heat flux and heat transfer calculations. The value for the tube wall conductivity was also confirmed by comparisons to published literature on stainless steels.

The tube wall outside temperature was also measured using 0.020-inch thermocouples which were silver soldered into the grooves cut in the tube. The measured wall temperatures, ideally should represent a point .01 inches below the cladding surface. Using the calculated wall heat flux from the primary fluid 00609-3.10 052991 63

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Figure 6-2: Measured and Fitted Primary Fluid Enthalpy Data 0c609 3 'DM2995 64

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WESTINGHOUSE CLASS 3 I

measurements (Equation 6-1) and correcting it for area changes; the cylindrical conduction equation can be rewritten to extrapolate the measured wall thermocouple value to the true edge of the tube. That is:

Do L"((Do .01) (6-6)

Twoe(x) = Twom(x) - qwi(x)(Do .01)

Where:

Twom(x) is the measured wall temperature at Do .01-inches Twoe(x) is the wall surface temperatur< vhich is extrapolated using the wall heat flux.

The calculated outside wall temperature agreed well with the measured outside surface temperature for low and medium heat fiux situations. When the wall heat flux was large (~105 Btu /HR ft2) the calculated cutside wall temperature exceeded the measured wall temperature. A detailed examination of the possible sources of uncertainty in the outside wall temperature calculation was made. Uncertainties such as the inside heat transfer coefficient, temperature effects on viscosity, wall

, conductivity, dimension tolerances, and temperature gradients in the primary fluid; 6

were studied by varying each of these effects, with the exception of the temperature gradient in the primary fluid.

The results of the sensitivity studies indicated that the inclusion of a viscosity correction to the inside heat transfer coefficient could help explain a portion but not all of the observed Jifference between the calculated walltemperature and the measured wall temperature. For the high heat flux cases, a larger radial temperature gradient will exist in the primary side tube flow such that the primary side thermocouple, which is located at near the tube center line, will indicate a center line fluid temperature which will be larger than the bulk temperature at that elevation. As a result, using Equation 6-2 may lead to an over-estimation of the inside wall temperature which will result in a higher calculated outside wall t.:mperature. Use of the primary fluid temperatures to calculate a heat flux from Equation 6-1 remained valid since an axial gradier.t is used in the calculation.

Examination of the calculated wall heat fluxes and wall superheats, indicated that the lower wall superheats obtained from the measured wall temperatures were more accurate and made the data consistent, rather than the higher wall temperature and superheats obtained from the wall temperature calculation.

Therefore, when correlating the heat fluxes, the measured extrapolated wall temperature were used.

Table 6-1 gives examples of the calculated wall hat fluxes, temperatures,inside heat transfer coefficients, and wall temperatures for a typical experiment.

D0609 31D052991 6-6

Table 6-1 Examples of PRHR Data From Steady-State Test b

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WESTINGHOUSE CLASS 3 The local fluid temperature is obtained by everaging the local thermocouple measurements 3-inches,6-inches,12 inches in front of the tube and 6-inches behind the tube at each elevation of interest. These thertrocouples are shown in Figure 61.

The local saturation temperature was calculated at each thermocouple elevation and used to obtain the wall superheat, Twall-Tsat, to develop the boiling curve for

the test d.'ta. The temperature traverses from the plume tests which were made at and arouno the tubes,while the tubes were boiling on the outside, showed liquid temperature at or above the bulk saturation temperature at the particular elevation.

This showed that a plume of hot liquid was present around the tubes when the tubes had sufficient wall superheat to boil. Therefore, correlating the data as a boiling curve qu," vs (Twan - Tsat) was the proper approach.

Using the fitted primary fluid temperatures and calculated heat flux; this heat flux can be integrated and cor@ared to the c,verall tube heat duty as calculated using the inlet and exit thermocouples as well as to the measured electrical power input.

I l

D0609 3 tD452998 6-8

WESTINGHOUSE CLASS 3 l I

7.0 TEST RESULTS The test data from the different test categories, and observations relevant to the expected performance of the PRHR heat exchanger are discussed below.

7.1 CONFIGURATION TESTS The purpose of the configuration tests was to confirm the applicability of the test results to the final PRHR physical configuration and to determine the reference configuration for the remaining tests. Specifically, the tests were performed to determine the effects of the following configuration parameters:

Distance of the heat exchanger to the IRWST wall Distance between rows of tubes Water level above the tubes Five configuration ttsts were performed. Configuration tests 1 though 4 involved varying the location of the heat exchanger tubes to a back wall, and placing a baffle in front of the tubes. Figure 7.1-1 shows the four configurations which were tested.

Configuration test 5 involved lowering the tank water level. The following is a description of each test:

Configuration 1 This configuration was originally termed the " baseline" configuration. The tubes were located in the annulus between the baffle and the tank wall, two feet in front of the back wall of the baffle. The water level was four feet above the tubes. See figure 7-1.1. This in the configuration with which the Phase I tests were conducted.

Configuration 2 in this configuration, the tubes were located only one foot in front of the back wall. This test was used to investigate the effect of the locating the passive RHR heat exchanger closer to the IRWST walls.

Configuration 3 in this configuration, the tubes were located 2 feet from the back wall. However, a baffle was inserted one foot in front of the tubes, beginning at an elevation equal to the top of the tubes and extending down to an elevation 16 inches above the bottom of the tank. The baffle was used to simulate a row of tubes 2 feet away from the PRHR heat exchanger tubes.

Configuration 4 in this configuration, the tubes were located 1 foot from back wall and the baffle was inserted 1 foot in front of the tubes. This test was also used to determine any effects of another row of tubes placed two feet away.

I 00609 3:1D052991 7-1

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WESTINGHOUSE CLASS 3 Configuration 5 This configuration test was performed with the same enfigura-tion as Configuration 2. However, the test was performed with the water levellowered two feet. The purpose of this test was to determine the effect that the water level above the tubes has on the time from PRHR initiation to steam release from the IRWST.

The following observations from the configuration tests can be made:

In general, heat transfer characteristics were similar for all configurations but appeared to be slightly enhanced with the addition of the baff;e and by inserting a back wall closer to the tubes. The heat transfer is slightly enhanced as the back baffle or the front baffle are moved closer to the tubes because of the increased fluid buoyancy around the tubes. The increased buoyancy drives flow up along the tubes resulting in higher local velocities and hence greater-free convection heat transfer. The higher flow along the tubes makes the heated tubes act as a pump which promotes increased mixing in the tank.

Figures 7.1-2 through 7.1-5 show the plot of heat flux versus outside wall temperature minus saturation temperature for configuration tests 1-4. Each data point represents the heat flux at a discreet point on the heat exchanger tube.

Tank mixing appeared to be improved with the baffle placed in front of the tubes as discussed above. Figure 7.1-6 is a plot of the average tank temperature against time for the 5 configuration tests, while Table 7.1-1 present the tank heatap rates for.the five tests. The tank water heats up at approximately the same rate for all configurations from the start of the test to the beginning of tank steaming. However, the configurations with the baffle placed in front of the tubes (C-03, C-04) heat up faster from the point of first steaming to bulk boiling. Since the heat input into the tank water from the tubes is similar for all configurations, the results imply that the tank water mixed better for those tests with the baffle. Furthermore,the amount of steam released for the tests from the time of first steaming to the time of bulk boiling should be less because the heat input to the tank was used to raise the bulk tank water temperature.

7.2 PLUME TESTS A series of plume tests were performed as described in section 5. In addition, plume data was taken for the various configuration tests described earlier. Selected results of these tests are presented in Figures 7.2-1 through 7.2-6. The plots are of the maximum recorded plume temperatures at locations around the outside tube for various tube flow rates, number of tubes operating, and tank configurations. The shape of the measured plume around the tube was similar in all cases. The highest tank temperature recorded was 228 F which occurred at the lowest elevation. This was expected because the saturation temperature at the lowest elevation is highest due to the head of the tank water.

D0609-3 10052991 - 7-3

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D0609 3:1D4)52991- 79

WESTINGHOUSE CLASS 3 A comparison of the plots for tests P 01 and P-02 show that the shape of the plume ,

of tube 1 was not affected by the operation of the other tubes. These results seem .

to indicate that the tube pitch selected is adequate and that heat transfer _ would not be improved significantly by increasing the tube pitch. This will be confirmed by results of selected steady-state tests. A comparison of the plots for tests P-01, P 03 and P 05 show that the shape of the plume is also unaffected by the primary side tube flow rate. ,

A comparison of plots for test P 01 and C-02 show that the shape of the plume was largely unaffected by the placement of the back wall one foot closer to the tubes. A '

comparison of the plots of C-03 and C-04 show that the plume temperature is generally higher than the other configurations. These were tests where the baffle was placed in front of the tubes. However, the plume was limited to 3 inches on either side of the tube. The plume test shows that a buoyant plume does exist around a given tube and becomes slightly larger as one moves up the tube toward the top of the tank. The zone of influence of the buoyancy is limited to the -

immediate area around the tubes, so that rows of tubes located a few feet apart do not interact and can be assumed to behave independently. Thus, the data from this series of experiments will also apply to multi-headered tube arrays. Therefore, this observation combined with the very s;milar heat fluxes for tests C-03 and C-04 indicate that no interactions between a second row of heat exchanger tubes exists provided that the distance between the rows is 2 feet or more.

These observations are important for demonstrating the applicability of the test data to the current AP600 PMR heat exchanger design. As described earlier, the current heat exchanger configuration is 6 rows of vertical heat exchanger tubes located 2 feet apart.

As a result of the plume tests and configuration tests which were performed before the steady state and transient tests, the standard configuration at which the remaining tests were run was with the tubes 2 feet from the back wall, no baffle, and the water level lowered 2 feet. This configuration was chosen because of the following reasons:

The baseline configuration (C-01) demonstrated the worst results in terms of heat flux and tank mixing. This, combined with the fact that the plume was limited in size for the cases with the baffle (C-03, C-04), gives the highest level of confidence that test results obtained for tests run with this configuration will be conservative.

The water level was chosen to be 2 feet above the tubes. This option was selected due to the current heat exchanger tube length of 20 feet, and therefore the IRWST water levelis only 2 feet above the top of the tubes. Since the results of test C-05 showed no appreciable difference in the time to measurable steam formation between C-05 and C-01 or C-02, the aforementioned water level was chosen.

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WESTINGHOUSE CLASS 3 7.3 STEADY STATE TESTS For the steady-state tests, the tank of water was allowed to heat up to 212 15'F.

Once the tank was heated, a series of tests were performed for a given primary tube flow rate and pressure, initially the primary inlet temperature was fixed at the-highest value (up to 650'F) possible with the heater. The primary fluid mass flow was held constant and the primary inlet temperature was decreased in approximately 50'F decrements. Once a steady state was reached, several data scans (at least 10) were taken at every temperature decrement. These scans were reduced and averaged to obtain the wall heat flux.

Figure 7.3-1 gives a composite plot of the measured data from a steady-state test (Test 553). The measured primary tube temperatures, wall temperatures, and average fluid temperatures are shown on the figure. With the tank temperature near the boiling point (at atmospheric pressure), the heat transfer process is a combination of vertical free convection and weak boiling at the tube surface.

Figures 7.3-2 to 7.3-4 shows the boiling regime on the outside of the PRHR tubes at different elevations. Weak boiling is observed at the bottom of the tubes while developed boiling is observed at the top of the PRHR.

Figure 7.3 5 shows the calculated heat flux on the outside of the PRHR tubes, using the energy balance from Equation 6-1 for a series of primary side fluid temperatures.

The data for each individual test is represented as a string of data points with the lowest heat flux and the smallest tube wall superheats (Twall- Tsat) value at the bottom of the PRHR tube. The high heat flux points have larger tube wall superheats and occur at the top of the u.be where the hot primary fluid enters. Each set of data is for a diHerent primary side temperature, as well as different primary side flows. The tank water is heated to nearly boiling. The data shows a combination boiling and free convection heat transfer. At low primary fluid temperatures, the heat transfer is dominated by free convention. As the primary temperature and hence the wall superheat increases, the heat transfer mode -

changes to boiling. Figure 7.3-6 shows a conventional free convection correlation, Eckert and Jackson (4) and boiling correlations, Rohsenow(5), McAdams(6) and Jens Lottes(7), compared to the PRHR data. Also the Zuber(s), pool boiling critical heat flux (CHF) limit is shown to indicate that CHF does not occur on the outside of the tubes.

A comparison of results from steady state tests 5-05,5-11, and 5-14, which were all run at 1 gpm, the measured heat flux is unaffected by the number of tube operating.

Figures 7.3-7 thru 7.3-9 show the measured heat fluxes for these tests at inlet temperatures from 650'F to 250*F. As is shown, the data is very similar for all three tests, regardless of whether 1 tube,2 tubes, or 3 tubes were operating. This confirms that the selected tube picch (1.5" centerline to centerline) is adequate and that no benefit would be realized from increasing the tube pitch.

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00609-31DT)52991 7-18 1

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WESTINGHOUSE CLASS 3 Comparisons of the overall tube neatduty are shown in Figure 7.310 for the different test conditions. As expected, higher primary side initial temperatures and higher flow result in increased heat transfer (Btu /hr) to the simulated IRWST.

7.4 TRANSIENTTESTS

' In the transient tests, the tank was started at or near room temperature and was heated up by the primary tubes. The data was recorded more frequently to obtain the tank temperature and mixing behavior as well as the primary tube fluid and wall temperatures.

The area of interest in these experiments is the temperature distribution within the IRWST simulation. That is, how well does the IRWST water mix when the PRHR is functioning, and whether hot and cold spots are created. As indicated earlier, there were several thermocouples located at different regions within the tank to monitor the tank temperature. Figure 7.4-1 shows the location of the vertical structure which supported several fluid thermocouples at different elevations. Figures 7.4 2 and 7.4+3 show the transient heating of the sirnulated IRWST tank by the PRHR heat exchanger. Figure 7.4 2 shows the response of the tank fluid thermocouples mounted at position Din the center of the tank. As the figure shows, the upper elevations heated up first; with the lower elevations were initially delayed and then heat up. At 7000 seconds, when the uppermost elevation is at 212'F, there is a 35'F vertical gradient between the top tank elevation (23.917 feet) and the bottom elevation (4.917 feet). Figure 7.4 3 shows all the tank fluid thermocouples at the tank mid plane, the 13.92 feet elevation. As indicated by the figure, there is excellent radial mixing since all the locations read the same temperature. As these figures show, there is a stratified flow situation established with the PRHR heat exchanger acting as a thermal pump. The tank water is heated along the tubes, first by natural convection, and later by weak boiling. The heated plume which surrounds the PRHR tubes flows up to the top of the tank, while drawing some water in along its length and spreads across the top of the tank as a hot liquid layer. This hot liquid layer displaces colder liquid which flows down the tank and toward the heated PRHR. The PRHR exchanger is a very effactive thermal pump which quickly -

heats the tank water. Figures 7.4 4 to 7.4 7 show the tank fluid temperatures at different times during the test indicating the uniformity of the heating within the o tank.

7.5 UNCOVERY TESTS All the experiments discussed in Section 7.1 to 7.4 had the PRHR exchanger covered with a single or two phase mixture. A specific series of experiments were also performed for which the simulated PRHR and IRWST were uncovered to different levels (75%,50%,25%) to see the effect on the exchanger performance and heat transfer.

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VESTINGHOUSE CLASS 3 b

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WESTINGHOUSE CLASS 3 b

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Figure 7.4-7: Tank Temperature at a Given Time for a Transient Test 00609 3:10 052991 7 36 i i i -

WESTINGHOUSE CLASS 3 The tube bundle uncovery data was reduced using the same set of equations for the  ;

heat flux and wall temperature as described above. Figures 7 51 and 7 5 2 show the comparison of the fitted primary fluid temperatures and the measured outside wall  !

temperature for both instrumented tubes for a test with approxirnately 25% of the tube bundle uncovered. The outside wall temperatures below the two phase level in the tank data present a clear indication of good cooling (nucleate boiling) and poor cooling (steam cooling) above the two phase mixture height. The primary fluid temperatures show the same behavior, and the change in the slope of the curve represents the good cooling Similar comparisons for the tube wall temperatures for a 75% uncovery core are shown in Figures 7.5 3 and 7.5 4. For these tests more of the tube is at the primary tube side temperature. The PRHR tube bundle uncovery experiments are similar to rod bundle uncovesy experiments. A quench front exists below which nucleate boiling occurs, while above the dryout front the heat transfer is primarily steam cooling with small entrained droplets. The heat fluxes calculated from the primary side thermocouples, will smear the heat transfer effects acoss the interface so a dryout front can not be detected from this data. However, the wall temperature measurements can more easily detect the front as it would pass the thermocouple location.

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WESTINGHOUSE CLASS 3 b

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Figure 7.51: PRHR IWRST Uncovery Temperature Data (25% Uncovery) for Tube 1 D0609 31DC52991 7 38

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Figure 7.5-2: PRHR IWRST Uncovery Temperature Data (25% Uncovery) for Tube 2 D0609-3 1DC52991 7 39 l

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s Figure 7.5 3: PRHR IWRST Uncovery Temperature Data

'(75% Uncovery) for Tube 1 00609 3:1D452991 7 40 1

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WESTINGHOUSE CLASS 3 9

8.0 CONCLUSION

S ,

The following conclusions can be drawn from the test results.

1) The heat removal capability of the PRHR heat exchanger has been characterized. A heat transfer correlation based on the test data will be developed for the Nuclear Safety computer codes to assess PRHR performance. -

2) The mixing capability of the water in the PRHR test loop was very good.

Therefore suf9cient mixing of the water in the IRWST can be expected and ,

localized boiling or " hot spots' will not be a problem. The temperature in the PRHR test tank was nearly uniform throughout the tank at a given elevation, thus proving that most of the tank volume will be used as a heat sink The interface of the pronounced vertical temperature gradient in the tank is moving continuously downward when the tank water is boiling, and after -

several hours of heat removal most of the tank water may reach a uniform boiling temperature of 212*F. The desired objective of demonstrating good mixing of the IWRST is therefore achieved. -

3) The data from different possible PRHR configurations showed no realimpact on the heat transfer performance indicating that the existing data equally applies to the revised PRHR design with multi tube banks.

4) The PRHR performance was characterized with partial drain downs of the IWRST which can be used to support the safety analysis models of the PRHR, 00609-31DS52991 81

l WESTINGHOUSE CLASS 3

9.0 REFERENCES

1) Petkhov, B. S., " Heat Transfer and Friction in Turbulent Pipe Flow with Variable Properties", Advances in Heat Transfer, Volume 6, pp. 503 564, Academic Press, New York,1970.

2) Kreith, F., and Bohm, M. S., Principles of Heat Transfer, Fourth Edition, pp.

324 325, Harper and Row Publishers, New York,1986.

3) Dittus, F. W., and LM.K. Boelter, University of California Berkeley Publ.

Eng. Vol. 2, pg. 433,1930.  ;

4) Eckert, E.R.G. and T. W. Jackson, " Analysis of Turbulent Free Convection Boundary Layer on Flat Plate," NACA Report 1015, July 1950.

5) Rohsenow, W. M., " A Method of Correlating Heat Transfer Data for Surface Boiling Liquids," Trans ASME Vol. 74, pp. 969 975,1952.

6) McAdams, W. M., Kennel, C. S., Carl, R., Picarnell, P. M. and J. E. Drew,

" Heat Transfer at High Rates to Water with Boiling," Ind. Eng. Chem., Vol.

41,(1945).

7) Jens, W. H. and P. A. Lottes, " Analysis of Heat Transfer, Burnout, Pressure Drops and Density Data for High Pressure Water", ANL 4627 (1951).

8) Zuber, N., and M. Tribus, "Further Remarks on the Stability of Boiling _ Heat Transfer," Report 58 5, Dept. of Engineering, University of Calif., Los Angeles,1958.

00609 31DC$2991 91

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