a NYLUNDK. M. BECKERR EKLUND0. QELIUS1. HAGA

D. MALNESA.OLSEN2. ROUHANIJ. SKAUQF. AKERHIELM

FRIGG LOOP PROJECT FFHGG-3

Hydrodynamic and heat transfer measurementson a full-scale simulated 36-rod Marviken fuel elementwith non-uniform radial heat flux distribution

ASEA-ATOMAS ATOmMMQIf tTOCKHOHi

R4-494/RL-1154

HYDRODYNAMIC AND HEAT TRANSFER MEASUREMENTS ON A FULL-SCALE

SIMULATED 36-ROD MARVIKM FUEL ELEMENT WITH NON-UNIFORM RADIAL

HEAT FLUX DISTRIBUTION

O Nylund , K M Becker', R Eklund1, O Gelius , I Haga ,

4 5 4 2 5A Jensen , D Maines , A 01 sen , Z Rouhani , J Skaug ,

and F Ikerhielm

The full-scale loop test program for the boiling channels of

the Marviken reactor included investigations of axial and ra-

dial void distribution, single- and two-phase pressure drop,

natural circulation mass velocity, stability limits as well as

detailed dynamic characteristics, and burnout in natural and

forced circulation. J?h experiments started with full length

uniformly heated 6-rod and 36-rod test sections (i,2 )followed

by a 36-rod test section with a non-uniform radial heat flux

distribution. A 36-rod test section with an* axial as well as

a radial power peaking typical for reactor conditions, has also

been tested and the results will be published in the near fu-

ture.

This report summarizes the results obtained for the second 36-

rod clustBi-, having radially non-uniform heat flux distribution.

The detailed results ha/e been given in a series of internal

reports (3, 4, 8, 12, 18, 26, 31). Also included in this report

are the results of a few tests of existing calculation models

against the measured data.

1. ASEA-ATOM, Västerås, Sweden

2. AB Atomenergi, Stockholm and Studsvik, Sweden

3. Royal Institute of Technology, Stockholm, Sweden

4. Danish Atomic Energy Commission, Risö, Denmark

5» Institutt for Atomenergi, KJeller, Norway

The tested cluster consisted of 36 rods with 4*365 m uniformly

heated length and 13.8 mm outer diameter• In addition an un-

heated center rod of 20 mm diameter was present. The radial pe-

aking factor was 1.18, the peripheral rods having the highest

heat flux. Prototype reactor spacers were used.

The investigation was concentrated on conditions relevant to the

Marviken reactor (natural circulation, G~1000 kg/m s, p - 50

bars), but other conditions have also been studied. A pressure

range from 30 to 90 bars has been covered.

AH far as the Marviken reactor is concerned, the experimental re-

sults (accounting roughly for the main differences between loop

and reactor conditions) indicate that sufficient margins against

burnout or hydrodynamic instability should be present. Burnout

geems to be the prime power-limiting factor.

Comparisons with the results of the ail-uniformly heated cluster

(2) reveal no large influence of the radial heat flux distribu-

tion on the investigated characterisics. A significant decrease

in mass velocity and stability limit in natural circulation was

caused, at least mainly., by an additional outlet throttling in-

troduced for experimental reasons. Burnout was obtained on the

peripheral rods, as compared with burnout on the inner rods in

the uniform case, but the channel power at burnout did not chan-

ge significant!/. A small decrease ( £ 3 $>) was observed in the

average void at higher qualities (x £ 15 $ ) . As expected, a

Blight reduction in void was observed for the central regions.

Some of the measured data have been used for a preliminary check

of computation programs available in Sweden, Denmark and Norway.

The tested programs are BOSFLOW for steady state hydraulic cal-

oulations» HYDRO II and RAMONA for complete hydrodynamic calcu-

lations, and HAMBO for subchannel analysis including burnout pre-

diction. Stability limits calculated with HYDRO were generally

II # too high, while those calculated with RAMONA were about 5 #

too low. The discrepancies are believed to be doe to the corre-

lations used for void and friction rather than the models them-

selves. Burnout predictions with the Danish version of the HAMBO

program, u»ing the Becker correlation, were made with errors with-

in i 10 J*. Predictions vith tha Becker correlation applied in thanormal vay on tha bundle as a whole overestimated tha burnoutheat flux hy O - 18 £. Tha largest errors vara obtained at higiermass velocities.

Printed and distributed in November 1969

Idet of contents

1. Introduction 1

2. Apparatus 3

2*1 Loop and power supply 3

2.2 Instrumentation 3

2.3 Test section 4

3« General survey of experimental investigation 7

4. Measurements and discussion of results 12

4*1 Natural circulation steady state experi-ments 12

4-2 Void distributions 20

4.3 Pressure drops 26

4*4 Dynamic characteristics 33

4.5 Steady state burnout 38

5. Comparsion with steady state and dynamic mo-dels 42

5*1 Variation of mass velocity with heat flux

in natural circulation 43

5.2 Limit of stability 46

5*3 Transfer functions 47

5*4 Void fractions along the heated channel 50

5*5 Subchannel analysis 506. Conclusions with special reference to the Mar-

viken reactor 53

6.1 General 53

6.2 Comparison of present experimental resultsand Marviken operating conditions 53

7* General conclusions 56

Acknowledgements 59

Nomenclature 60

References 62

Appendix 1 A1

figures 1 - 5 3

1. INTRODUCTION

The present report covers the third phase of an experimental

investigation concerning the hydrodynamics and the heat trans-

fer properties of the boiling channels of the Karriken boiling

heavy water reactor.

The fuel elements for the Marviken reactor consist of 36 rods

of 13*8 mm diameter and 4420 mm heated length, mounted within

a shroud of 160 mm diameter. The 36 rods are distributed on

three circles, the inner circle including 6 rods, the inter-

mediate 12 rods and finally the outer circle including 18 rods.

In addition,an unheated center rod of 20 mm diameter is intro-

duced to carry the spacers.

Before studying the complete 36-rod bundle it was decided to

investigate a full length 6-rod bundle, which was geometrically

identical to the central portion of the 36-rod bundle. This

study was carried out in the 2.5 MW loop, FRÖJA, and the re-

sults were reported by Nylund et.al. (1).

During the second phase of the investigation, a full-scale

uniformly heated 36-rod bundle was tested in the 8 MW FHIGG

loop. The results, which have been reported by Nylund et .al.

(2), included axial- and radial void distributions, two-phase

flow pressure drop, burnout at steady state, natural circula-

tion mass velocity, stability limit and characteristics of

transient conditions.

The purpose of the present measurements was to investigate

the effects of the radial heat flux depression in the central

region of the fuel elements. The geometry of the test sec-

tion was identical to the 36-rod reactor channel. The main

difference from the reactor conditions for the present

measurements, however, was the axially uniform heat flux.

Mention may be amde of the fourth phase of the investigation

which is also completed. There, the axial- as well as the

radial heat flux distribution of the 36-rod bundle was non-

uniform. The results from that bundle will be published in

the near future.

The experiments reported, were carried out at the laboratories

of ASEA-ATOM, Västerås, as a joint project between AB Atomenergi and

ASBA-ATOM. However, the Banish Atomic Energy Commission and

Institutt for Atomenergi, Norway, which entered into the fourth

phase of the project, have also participated in the present

work.

2. APPARATUS

2.1 Loop and pour supply

The experiments were performed in the 8XV FRIG* loop, previous-

ly described in Reference 2. The main geoBetritml data of the

loop are summarised in Fig.1 where the lower end of the

heated length of the present test section, F¥-36b, is used

as a reference level.

The loop can b* operated at natural as veil as forced circu-

lation. L'*2£* iiameter piping is used for the downoomer.

The inlet throttling is changed by means of a valve in the

natural circulation branch, the loop pressure is controlled

by regulating the water flow from a cooling circuit to the

spray condenser, and the inlet suboooling is controlled hj

feeding cold water into the upper part cf the downooaer.

The heating power for the test section ia obtained fro* an

8MW, 80 kA, DC ower supply. The voltage is continuously

regulated and o&n also be oscillated for transfer function

measurements•

2.2 Instrumentation

The instrumentation was mainly the same as in the previous

tests (2), and is only briefly commented here. A review of

the BOS t important loop parameters and how they are defined

and measured is given in Chapter 3*

Mass velocity has bee i measured with a venturi meter in the

downcomer and, for low velocities at forced circulation,

an orifice plate flow meter. For dynamic measurements a fast

response EP-cell (Statham) was connected to the venturi unit.

Short, large diameter tuber were used to minimise the damping

(A RAMAPO drag body flow meter had been installed but did

not work properly).

Pressure drops have been measured with Barton-cells, calibrated

at operating pressures in a special rig.

Coolant temperature distributions have been measured with chromel-

alumel thermocouples of fast response type.

Void fraction has been measured along tha test section with

the gamma ray attenuation system used in earlier tests (1,2).

A Co - 60 source was used, and the channel cross section was

penetrated in twelve different directions. Exit void fractions

were measured with a turbine flow meter and, for dynamic

studies, an impedance void gauge. The experience with these

instruments, developed for the Marviken reactor, is reported

in Ref. 4.

Burnout was detected with bridge type detectors. Four rods

were connected to each detector.

The data collecting and recording system used during the

measurements is built up around the data acquisition

unit RAMSES (5). The system has been used for static void

measurements and for all dynamic measurements. Analog

signals have been filtered, suppressed by bias voltages

and amplified in operational amplifiers with active filters.

Recording was made on a 4-channel Sanborn recorder and on

the RAMSES via an 8-channel multiplexer and an analog--

to-digital converter. Programmed power-perturbations for

transfer function measurements, have been obtained by means

of a programme unit synchronized with the RAMSES.

2.3» Test section

The main data for the test section, PT-36b, are given in

Figs 2 and 3 and in Table 1, where the data for the prece-

ding tut section, PT-36a (2), and for an actual Marviken

boiling channel are also given.

Table 1

Number of heated rods

Heated length, mm

Radial heat flux distribu-tion

Axial heat fluxdistribution

Heated rod, OD, mm

Unheated center rod,OD,mm

Shroud, ID, mm

Equivalent diameter, mm

Heated equiv. diam., mm

Number of spacers

Chimney height, mm

Operating pressure, bars

Inlet subcooling, C

Inlet throttling, velocityheads

Coolant

Marvikenboilingchannel

36

4420

Nonuniform

Nonuniform

13.8

20

160

27.337.2

71470

49.5

2.5

13

D20

PRIGGPT-36a

36

4375

Uniform

Uniform

13.8

20

159.5

26.936.6

8

1540

variable

variable

variable

H20

FRIGGPT-36b

36

4365

Honuniform '

Uniform

13.8

20

159.5

26.936.6

8

1550

variable

variable

variable

H20

1) Relative radial heat flux distribution of PT-36bi

6 inner rods 0*742

12 interjacent rods 0.860

18 peripheral rods 1.180

The mo8t significant feature of FT-36b, oompared to PT-36a,

is the nonuniform radial heat flux distribution. Another

important difference between the two test seotions refers

to the design of the heater rods and the electrical connec-

tions. The rods of FT-36a were of the coaxial type (2), .while

for FT-35b simple tubes with eleotrioal connections at top

and bottom were used. This design caused a small additional

outlet pressure drop, and also some limitations for the use

of the gamma void gauge,but it was less expensive and more

reliable. Details of the design are shown in Fig* 4*

The eleotromagnutic field outside the test section, not present

in the case of FT-36a because of the coaxial type rods, was

minimised by feeding the current to the top oonneotion in water

oooled tubes along the test section. This arrangement prohi-

bited measurements with the gamma void gauge at the uppermost

part of the test section, but it was necessary for acceptable

functioning of the gauge.

Prototype reactor spacers, Marviken type G (same as for PT-36a),

were employed. The positions of the spacers are pointed out

in Figure 2. For practical reasons two different types of

electrically insulated spacer fittings had to be used.

The test section wac provided with pressure taps and thermo-

couples at the positions shown in Fig. 2. The stations for

the gamma void gauge are also given in this figure. As

mentioned above, a turbine flow meter and an impedance void

gauge were mounted at the exit. The positions are given in

Fig. 2. A riser, intended to simulate the steam separator

of a Marviken boiling channel, was fitted to the test section.

The details of this riser, the same as for FT-36a, are also

given in Fig. 2.

3. GENERAL SURVEY OP EXPERIMENTAL INVESTIGATION

The experiments were carried out during two test periods,

November and December 1967, aooording to the program out-

lined in Referenoe 6. Measurements have been performed

on axial and radial void distribution, single- and two-phase

pressure drop, natural circulation mass velocity and*

stability limits as well as detailed dynamic characteristics

and burnout in natural and forced circulation.

The detailed results of the different types of measurements

have been given in internal reports (4» 8, 12, 18, 26,31 )•

Some of the more signigficant results are presented

and discussed in the following chapters of this report.

A complete record of the measurements is found in Appendix 1.

The different measurements are identified by the usual type

of code number. The first figure refers to the test section

(4 • FT-36b), the next two figures refer to the type of

measurement, and the last three figures identify the indi-

vidual measurement.

A summary of the range of loop conditions covered in the

different investigations, is presented in Tables 2a - g

below. The figures given there, are of course approximative.

Table 2a. Natural circulation steady state mass flow measure-

ments. G = f\Q)

p (bars)

30

50

70

sub

3•i „,

3,

<°o)

2515

kin

5,5 -5,

(v.h.)

13

- 260

14

Table 2b, Complete void distribution measurements

p (bars)

30

50

70

87

Ad

3

3

3

CVI 1

sub (°C>

, 25

- 30

- 16

22

22

22

44,

(W/om2)

- 66

- 66

- 66

74

G (kg/m2s)

510-1110

490-2050

500-1970

980, 1610

xex

5 -2 -

5 -14

GO22

25

27

Table 2o. Radial void distribution measurements at level 06

p (bars)

50

70

87

A* ,(<>C)subv '

3-25

3-20

3

(ojA) (¥/«2)

74, 89

14 - 89

66

G (kg/m2s)

530-2050

550-1900

700

ex v/ '

5-39

7-41

32

Table 2d. Single-phase pressure drop measurements

*in ( C)

20 - 295

G (kg/m2s)

500 - 2620

Table 2e. Two-phase pressure drop measurements

p (bars)

30

50

70

87

Ad

3

1

3

2

sub (°C>

, 25

- 30

, 16

(57A)

22

22

22

44,

(W/cm2)

- 66

- 89

- 66

74

G (kg/m2s)

510 -

490 -

500 -

980,

• 1110

- 2050

• 1970

1610

ex

5 -2 -

5 -14

(*)

22

26

27

Table 2f. Static turnout measurements

p(bars)

30

50

70

87

A$ . (oc )SUDV '

3 - 5

3 - 2 5

3 - 2 5

2 - 4

(c]7A)(w/cm2)

77 - 106

81 - 104

78 - 108

73 - 105

(q/A)nai(w/om2)

91 - 125

95 - 123

92 - 127

86 - 124

G(kg/m2s)

510-1140

420-1100

500-1790

560-1760

*exW

24-3927-4918-4520-42

Table 2g. Transfer function measurements

Ttype ofcircu-lation

Natural

Natural

*)Forced '

k inv.h.

5, 13

5-20

~103

P

bars

30

50

50

ASsub

°C

3

2-23

3,25

Q

MW

3

3-5

3

Transferfunctions

TQG'TQa

TQG'YQa'TQp'TQ$ in

TQG'TQa

Frequency

o/s

0.01-1.7

0.01-1.7

0.07-1.7

*) G »810 kg/m2s

The variables used to describe the loop conditions during the

investigations, are defined and measured as follows:

k. (velocity heads) is the total (downcomer included) inlet

pressure loss coefficient at natural circulation referred

to test section f o w area, P. It was measured by means of

a DP-cell (Barton type) connected to the pressure taps P11

and P28 (Figs 1 and 2). Estimated accuracy is ±0*3 velocity

head.

H(m) is the water level in the steam drum, with the lower end

of the heated length as the reference level. It was mea-

sured by means of a series of pressure taps and a DP-oell.

Estimated accuracy is - 0.05 m.

p(bars) is the pressure in the steam drum at the lower end

of the perforated part of the riser. It was measured

with two calibrated preoision manometers (high- and low

range) at the top of the drum and the readings have

been corrected for water level afcove the lower end of

the perforation. Estimated accuracy is - 1 of the

.reading in the range of interest.

. ( C) is the inlet subcooling, defined as the differencesub v 'between the saturation temperature at the riser outlet

and the inlet temperature, $ i n. Calibrated chromel-alumel

thermocouples at inlet and outlet have been used for de-

termination of subcooling. The accuracy is estimated to

be i 0.5°C.

Q (kW) is the heating power of the rod cluster. The readings

were made on a digital power meter (Hall-multiplier)

calibrated by separate voltage and current measurements

during the experiments. The readings have been corrected

for power developed in the electrical connections at top

(1 io) and bottom (0.8 fo) of the rods. The estimated accu-

racy in Q is - 1 tfo of the reading in the range of interest.

q/A (w/om ') is the surface heat flux. The mean heat flux

(q/A) is obtained by dividing the total power, Q, with

the total heated surface, A, measured at room temperature.

The maximum heat flux, (q/A) m a x, is obtained by multiply-

ing (q/1) with the radial peaking factor, 1.180, according

to room temperature calibrations. No correction has been

applied for the small (~ 1 $) power dependent changes of

the relative heat flux of the rods (7).

Q - å/F (kg/m s) is the specific mass velocity. F is the flow

area in the test section at room temperature* m was

measured by the venturi flow meter in the downcomer.

It has been oheoked by heat balance tests, and by compa-

rison with other flow meters. The venturi was specially

designed for low pressure drop ("because of the natural

circulation), which to some extent limited the accuracy.

Estimated accuracy in G is about - 20 kg/m s under nor-

mal conditions.

x ($) is the exit steam quality (at the end of the heatedexlength), calculated from the ordinary heat balance

equation. No correction has been applied for the heat

losses from the test section. The heat losses have been

estimated to be 20 å 30 kW, based on heat balance tests

and isothermal temperature measurements, but the re-

sults are quite uncertain. A major part of this power

is lost near the inlet of the test section. At a certain

power level (~ 3MW)the heat losses are compensated by

the heat production in the bottom connections of the

rods, not included in the value of Q.

4. MEASUREMENTS AND DISCUSSION OP RESULTS

4.1 Natural circulation steady state experiments

4.1.1 General

The main reasons for extensive natural circulation tests with

FT-36b,were to get indications of the influence of the radial

heat flux distribution on mass velocity and power limits,

and to investigate a broader range of loop conditions than with

FT-36a (2). Unfortunately, an additional outlet pressure loss,

caused by electrical cables and outlet instruments not present

in the natural circulation tests with FT-36a, made the compa-

rison of results from the two test sections more complicated.

On the other hand, this additional outlet restriction, k .

£* 1«o v.h., made the system more unstable and thus increased

the possibilites of making measurements at the stability limit.

The mass velocity in natural circulation has been measured

as a function of heating power at various values of inlet

throttling, pressure, and subcooling. Usually the power has

been increased until burnout or hydrodynamic instability has

been obtained* A noise analysis technique has been applied

for estimating the stability limit also in cases where burn-

out occurred prior to instability.

The mass velocity, G, was measured with the venturi flow

meter in the down comer. Estimated accuracy in G is about

-20 kg/m s. Por further details as to definitions, measuring

technique, and accuracy of the variables used to describe

the loop conditions during the investigations is referred

to Chapter 3* The noise measurements are discussed below.

The detailed results of these measurements have been re-ported previously (8).

4«1 • 2 .§teadgjB[tat•jflov measurements__

A survey of all the completed natural circulation tests is

given in Table 3(p 19).There are two cases at 30 bars, nine

cases at 50 bars and four cases at 70 bars.

Typical results are shown in Figs 5 and 6. Also shown in the

figures, are some statio burnout limits measured at forced

circulation (Seotion 4»5)« The effects of suboooling, inlet

throttling, and pressure are demonstrated» The qualitative

behaviour of the steady state flow curves is the same as

found in similar loop experiments with less complex test

sections (1,9 ) and at reactor conditions in Halden (1O).

A few tests were performed at very high inlet throttlings

(k. =130 v.h. and 260 v.h.) in order to check the de-

sign calculations on a throttle valve to be used at the in-

let of an instrumented fuel assembly of the Marviken reactor

during in-pile burnout tests. As expected, the mass flow

curves ware found to be almost flat for these cases (Fig. 5)

and the flow was steady up to the burnout limit.

In Fig. 6 comparison is made between results from experi-

ments with FT-36a (2) and FT-36b at loop conditions similar

to those expected in the Marviken reactor (k. »13 v.h.,

p =50 bars, A &sub * 5 C). Both experiments w«r« interrupted

because of burnout close to the static burnout limits measured

at forced circulation. The mass velocity was significantly

lower for FT-36b than for FT-36a. This is believed to be

due mainly to the additional outlet restriction in FT-36b

(k . = 1 . 0 v.h.), caused by electrical connections and out-out

let instruments. As discussed below, the influence of the

radial heat flux distribution on the mass velocity is probab-

ly small. The radial flux peaking did not either affect

the static burnout limits very much (if total channel power

is considered), but the burnout position changed from the

inner rods to the outer rods (Section 4.5).

The additional outlet resistance is also believed to be the

main reason for the lower stability limit for FT-36 b as

compared to FT- 36a. As indicated in Pig. 6 the stability

limits were estimated to 6.5 (± 0.2) MW and 7.4 (- 0.5) IN

respectively for the two cases. These estimates were obtained

by the noise analysis technique discussed below. For FT-36 b,

as shown in Table 3 and in Fig. 5 instability could be ob-

tained prior to burnout by decreasing the inlet throttling

or increasing the sub coo ling to values not too far from the

relevant Marviken data.

A more complete comparison between natural circulation

steady state mass velocities measured for the two 36-rod

test sections and the 6-rod test section FT-6 b (1) is made

in Fig. 1* The mass velocity is plotted versus inlet thrott-

ling for three different power densities (Q/V • 20,50 and

80 kw/l). The selected tests were performed at p =50 bars

and A - & , = 5 - 3 C . Differences in the subcooling for the

cases make the comparison somewhat uncertain, especially

at the lowest power density. The curves shown in the figure,

are best-eye-fits.

The effect of outlet pressure drop can be studied separate-

ly in the case of FT-6 b , which was tested with as well

as without additional outlet restriction (k . » 0.6 v.h.)OUT

caused by the impedance void gauge and the turbine flow

meter. As expected, the influence on the mass velocity of

the outlet resistance is found to be strongest at high

power densities and at low values of the inlet throttling.

The magnitude of the influence observed for FT-6b, seems to

support the assumption that the lower mass velocities obtained

for FT-36b, as compared to FT-36 a, were mainly caused by

the additional outlet restriction (k . .1.0 v.h.) for

FT-36 b.

It is also observed in Fig* 7 (as pointed out in Reference 2)

that a notable agreement exists between the results of

FT-36a and the 6-rod results for the oase with a normal out-

let. This is believed to be due to two or more effects can-

celling each other. It may be noted that the number of spa-

cers was 8 in FT-36a (as in FT-36b) compared to 5 in

FT-6 b, but on the other hand, the equivalent diameter was

2.69 cm for FT-36a (as for FT-36b) compared to 2.01 cm for

FT-6 b. This means that the increased pressure drop due to

the larger number of spacers in FT-36a and b was compensated

by a lower pressure drop in the rest of the cluster because of

the larger equivalent diameter.

4.1.3 Burnout and £ tab! Ii t £ .1 imits_

In Table 3 are given the power levels at which the different

experiments were interrupted, and the reasons why they were

interrupted. Also given in the table are approximative values

of the peak amplitudes of the mass flow oscillations, as ob-

tained from Sanborn recordings, just before the experiment

was interrupted.

The burnout limits were found to be close to those obtained

with steady flow in forced circulation, even in cases with

mass flow oscillations of the order of -10^. In the run no.

401162-173, which was interrupted only about 300 kW {<&%)

below the static burnout limit, mass flow oscillations reached

- 70$ without significant "burnout indications.

(The burnout detectors covered 1.3 m of the rods below the

end of heated length).

Stability limits have been determined also by the noise

extrapolation technique (11) applied in the earlier experi-

ments (1,2). Mass velocity noise was recorded at different

power levels and the standard deviation, a , was calculated

1/ a has been plotted versus channel power and a straight

line has been fitted to the points at higher power levels

and extrapolated to 1/0 « 0 ( a - °° ) . The power level

at this intersection is defined as the threshold of instabi-

lity. A few examples of such plots are shown in Pig. 8.

During the tests with FT-36b, a band-pass filtered (0.3 - 1 ops)

as well as a low-pass filtered ( 1 cps) mass velocity signal

was recorded and analyzed. The signal was obtained from the

fast DP-cell (Statham) connected to the venturi unit in the

downcomer. Signals from the impedance void gauge and the

turbine flow meter at the outlet were also recorded, but have

not been used in the analysis so far. The sampling interval

used in the digital recording,was 0.2 second, and the re-

cording time was usually 3 - 5 minutes. It has been found

that rather long recordings are necessary because of consi-

derable long time variations in the noise level.

It was expected that the use of the band-pass filter, tuned

for the resonance frequency of the system (»0.5 cps), should

improve tV.e accuracy of the extrapolation technique, compared

to the earlier tests carried out with a low-pass filter only.

However, the improvement, if any, seems to be small. As can

be seen in Fig. 8 the method is still rather uncertain and

cannot be relied upon for large extrapolations.

The extrapolated stability limits, with estimated errors,

are given in Table 3* The presented figures are mean values

of determinations with band-pass and low-pass filters.

Usually, the extrapolated stability limits are found to be a

few per cent lower than the power levels at which the experi-

ments were interrupted in cases where instability was undoubtedly

obtained. This is probably a result of the nonlinear damping

of large amplitude oscillations making "the real stability

limit" somewhat diffuse.

Extrapolated stability limits obtained on 6- and 36-rod

test seotions at various loop conditions, are compared in

Fig. 9* The stability limits are expressed as coolant power

densities (^V, kW/l).These are plotted versus pressure,

8ubcooling, and inlet throttling for oases with similar

values of the rest of che loop conditions. The irregular

behaviour observed for some of the points, is partly due

to the faot that the experiments were performed at some-

what different values of subcooling or inlet throttling.

However, some points are also rather uncertain due to large

extrapolations. This is especially true for the 6-rod results

in the case without additional outlet restrictions and with

high inlet throttling. It should be noted that if the power

density is considered, the burnout limits are lower for

FT-6b than for FT-36a. and FT-36b, which explains the more

uncertain extrapolations to the stability limits of FT-6t>.

The most accurate values in the figure are certainly those

of FT-36b, but it should be noted that the values at high

pressure (70 bar) and high inlet throttling (21 v.h.) are

very uncertain even in this case (as indicated in Table 3)*

Considering the uncertainties, especially for the 6-rod

cases, the results of Fig. 9 seem to indicate that the

stability limits of multirod channels of BHWR-type are

effected by pressure, subcooling, and restrictions at inlet

and outlet, in approximately the same way as for less complex

channels ( 9)« There may exist an influence of complicated

phenomena, such as internal "parallel channel behaviour"

of the subchannels of the cluster, not being discovered

by external mass flow measurements, but the indications are

that such effects should be small.

A more detailed analysis of recorded oscillations in flow

and void signals,would probably be of some interest for the

understanding of the instability phenomena. No suoh analysis

has been made so far, however. An example of reoordod signals

of large oscillations for a case just above the treshold of

instability,is shown in Fig* 10.

4.1.4 jJonolusionfl _on natural circulation tmjiaviour

The experiments with FT-36* have yielded significant cont-

ributions to the knowledge of natural circulation behaviour

of large clusters.

The indications are that a cluster of this size behaves

similar to less complex channels. This seems to be true for

the stability limit as well as the steady state mass velocity.

Nore information is needed, however, for a reasonable knowledge

of the parameters affecting the limit of stability. Some

additional information is obtained from the transfer function

measurements discussed in Section 4*4*

The differences observed between mass velocity and stability

limit of PT-36a and FT-36b, are explained, at least mainly,

by the difference in outlet restriction. The influence of

the radial power distribution is probably small.

The burnout limit was not significantly influenced by moderate

mass flow oscillations (- 10$). Violent oscillations (- lOfo)

did not induce burnout at power levels a few per cent

below the static burnout limit.

Comparisons with computer models are presented in Chapter 5,

and the consequences for the Marviken reactor are discussed

in Chapter 6.

Table 3 . FT-36b. Power l imitsat natural circulation

Hun

No

401251-258

401237-250

401162-173

401113-123

401124-135401149-154401136-148

401155-161401174-185

401186-195401196-204

401221-229401230-236

401205-214 <401215-220

k.in

v.h.

4.513.3

5.114.O

13.414.2

1 3 . 7

14.0

21.4131

261

4.74.6

13.6

13.5

P

bar

29.929.8

49.949.8

49.950.2

49.850.2

49.749.749.9

69.6

69.9

69.569.4

Ad ,sub

°C

3.03.0

3.0

3.06.6

10.0

15.0

24.32.8

2.93.0

2.814.8

2.8

14.9

Experiment interrupted

Q

kW

34954288

5898

614662606208

6053

6053611552814666

611564155878

6415

at

(UT)W/cm

51.3

63.0

86.6

90.192.0

91.189.O

89.0

89.977.568.5

89.994.1

86.494.*>

QAkW/l

55.968.6

94.4

98.3100.2

99.396.896.897.8

84.574.7

97.8102.6

94.0102.6

G

kg/m s

775610

700

649667705712

725632

455381

808822

740

749

because of

Burn-

out

X

X

(x)

X

X

X

X

(x )

X

X

Insta-

bility

X

X

X

(x)X

X

X

X

ÄGG

i

t 50i 50

t 70+ 3

i 7i 12

t 35t 25i 2

t 1.5i 1

1 1 . 5t 7+ 1

i 1

Extrapolated stabilitylimit

Q

kW

3380+1004200+50

5790^506520+2006200+.1 506180*505850+506000+.10075OOi5OO

71OO17OO

6450150

86OO+.1500

72001700

(VA)W/cm2

49.6

61.7

85.O

95.791.0

90.785.988.1

110.1

104.2

94.7126.2105.7

Q/V

kW/l

54.167.2

92.6

104.399.2

98.993.696.0

120.0

113 .6

103.2137.6115.2

4.2 Void distributions

4.2.1 E e£iJttenta ljprooejlure

Local densities has been measured by the use of gamma ray

attenuation. The apparatus is briefly described in Chapter 2

(else Refs 1 and 2) and a general survey of the measurements

is included in Chapter 3. The main body of the data was

collected at 50 bars. The total no. of points (216) were

distributed at the four nominal pressures of 30, 50, 70 and

90 bars to 25, 45, 24 and 6$, respectively. Out of 90 points

at 50 bars, 17 points were obtained at negative mean steam

qualities.

The cross-section-mean-void data points were obtained at six

positions along the test section (numbered G1 - G6 according

to Pig. 2 ) # The cross-section has been divided into 4

concentric zones, just as for the previous test section FT-36a

(see Fig. 11 )• Each data point thus also has a set of 4 radial

void data. The complete set of data is tabulated in Ref. 12.

A normal procedure also includes measurements on a mock-up of

the test section, filled with different pieces of plexiglass

simulating several void values and patterns.

Table 4 a. Statistics from FT-36b - mock-up

Standard W S A2 ^error y n-V

"Systematic L A (<f0)mean error" n

Totalchannel

1.6

\0.3

Zone •1

18.4

8.1

Zone2

8.5

-4.3

Zone1 + 2

4-5

-1.5

Zone3

3.3

0.2

Zone4

4.8

1.5

n . 12 (no.of cases), A . ameasured - "actua* W v o i d )

The value of such measurements is commented in Ref. 2 (p2i).

Comparing the mock-up statistics (Table 4»Obtained from this

test section and the previous FT-36a (2), one can see

that the statistical accuracy of the FT-36 b-mock-up is higher,

mainly due to the difference in the heater rod design.

During the measurements, however, heavy drifts in the gamma-

counting were encountered. Some equipment was exchanged,but

a more frequent standardizing was also necessary. During the

treatment of the raw data, it was seen that errors were en-

countered more frequently at particular gamma beams and posi-

tions. A rational computing procedure was thus possible for

all pressures except for the 30 bars-data. For this pressure

usually 3 out of 12 beams (Fig 11) were cancelled for all 6

G-positions9against normally,1 or 2 at positions G2, G4 and

G6 (for more details see Ref. 12 )•

4.2.2 Vodd

The cross-section mean void data for 50 bars pressure are

plotted in Fig. 12 and the radial zone void data in Figs 13a,b.

As to Fig. 12, the scatter of the data in the (a,£)-plane

is about as for the all-uniform heat flux bundle FT-36a.

Compared to the best-eye-fit curve of the FT-36a-data

(Ref. 2 ), there is a marked reduction in void for the

present bundle, the difference increasing from zero at

about \&fo quality to about 3$ void at ~25$ quality.

This difference in mean void for the two test sections is

also pointed out on the best-eye-fits of Fig.15.

In the overall view of pressure dependency, it looks like

the 50 bars-data of FT-36b approaches the 70 bars-curve too

"quickly" in the (x-20)-region. On the other hand, the

30 bars-curve seems to approach the 50 bars-data of FT-36a

in about the same mannor.

Interesting in this respect are also the results obtained

for radial void. Again compared to the FT-36a-results, it

is seen from Figs. 13a and b that the innermost region

(zone 1) only,is reduoed noteworthy, but since it contri-

butes only % to the mean void, the reduction of mean void

at high qualities stems from other zones as well,but mainly

the peripherial region (zone 4)in spite of the higher power

to the periferial region for the PT-36b-bundle.

In view of the following table, the differences in zone voids

for the two test sections are somewhat unexpected as to the

two intermediate regions (zones 2 and 3). But of course,

one must keep in mind the influence of radial flow distribu-

tion.

Table 4b. Subchannel t>ower density peaking factors

(circular subdivision)

Zone no.

PT-36a

PT-36b

1

1.423

1.060

2

1.338

1.094

3

1.340

1.400

4

0.5750.677

Por other pressures no data exist to compare the influence

of radial power within the Marviken bundle. But the influ-

ence of pressure is shown on Figs. 14 and 15. The best-eye-

fits to the 30 and 90 bars-data are somewhat weakly founded

and should be judged accordingly.

The turbine flow meter located in the riser (Pig. 2 ), gave

as previously, void data generally above those within the

bundle in the bulk boiling region (Pig 12 ).

4*2.3 Void_Results-

Some data are also obtained in the sub coo led region. As is

seen from Pigs 12 and 16, except for one run, the mean void

data are much grouped together. (This was also the case for

the 4 runs at 30 and 70 bars indicated on Pig. 16.)

In addition to statistical variations, accuracy in positioning

of instrument and rod bending due to electromagnetic field,

there are also other factors that may affect the accuracy of

the zone-void-data in the subcooled region. In the bulk boi-

ling region, the temperatures are not greatly different from

the saturation temperatures. In the subcooled region, however,

the temperature over the cross-section may possibly vary con-

siderably. The flow conditions near the test section inlet

are unknown (Ref. 15 )• Nevertheless, except for a few points,

the scatter of the zone-void-data (Figs 13a and b) is about

the same over the whole range of qualities investigated.

The temperatures on which the calculations are based, are

obtained from thermocouples, located in the peripherical

region (zone 4). This is assumed to be the best choice since

this covers the largest fraction of area and contains the

most liquid. The low scatter of the mean void data of the

subcooled region seems to strengthen this assumption. Note-

worthy in this connection, is the high void fraction of

zone 3 (Fig.13b ), the zone of highest power density.

(Void distribution may possibly throw some light on the

mixing problem in bundles (Ref. 15 ))•

On Fig. 17 are shown some best-eye-fit curves of zone-voids

in the subcooled region. Two of the subcooled runs on FT-36b

may fairly well compare to two runs obtained from the

FT-36a-bundle as to subcooling, flow and power. As is seen

on Figs. 18 and 19 , the local void data in the subcooled

region show differences which definitely are results of the

differences in radial power distribution for the two bundles

FT-36a and FT-36b.

4.2.4 Qeneraljon the FJMjSb^ VoidJData

The main part of the drifts encountered in the gamma counting

has been taken care of by frequent standardizing. As to void

runs themselves, the possible remaining part of the drifts

should at least for the mean void data,amount to very small

errors. Only one of the sets of calibration runs have been

used, however, but the cancelling of particular beams may

have removed particular peaks in drifts. (More calibration

runs exist and further averaging with these may prove

advantageous.)

In all, the accuracy of the void data for FT-36b does not

seem to be much different from that of the PT-36a bundle.

The only known absolute errors are those due to the electro-

magnetic bending of rods in FT-36b, but the influence of

this on the mean void data is definitely negligible. Small

corrections may be applied to the zone-void data, and the

following table demonstrates the influence of the electro-

magnetic rod bending.

Table 4 c. Errors in zone-voids due to electro-magnetic

rod bending calculated for 4MW power and 50 bars

pressure. PT-36b

Zone no.

Eventualcorrection (fo void)

1

+0.7

2

+0.9

3

+1.7

4

-1.6

The above errors, which are proportional to power, has not

been applied to the tabulated and plotted results (Ref. 12).

Generally one may conclude that the change in radial heat

flux distribution from that of FT-36a to PT-36b resulted in

noticeable changes in the radial void distribution. The cent-

ral region (zone 1) reduced considerably in void fraction,

in line with the change in the power density, while the inner

intermediate radial region (zone 2) reduced comparably less.

For the outer intermediate region (zone 3), the increase in

void was comparably high. The peripherial region (zone 4)

demonstrated no dependency on changes in power density, and

from a mean quality of about 20 $ the void reduced,in spite

of higher power density for FT-36b. The virtual independency

of flux density of peripherioal region may be explained by

relatively high Base flow for this region.

As to the mean void of PT-36b, the results indicate increased

8lip compared to FT-36a in the region oT * 7OJÉ to öT» 85jt,

a possible result of moving power radially fro» a region of

low relative mass flow to one of higher flow* The contribu-

tion to mean slip from the peripherial region at x > 20£,

however, must be due to other faotors as e.g. Migration of

voids to the region inside due to higher local axial pressure

drop there. It is, however, difficult to prove the signi-

ficance of the apparent difference of the slip behaviour of

the two bundles from the void data alone.

Finally, mention may be made of the series of least squares

fits of the void data of both FT-36a and FT-36b given in

Ref. 16. The regression analyses demonstrate significance

of all basic loop parameters and that normal standard devia-

tions of the slip ratio come correspondingly close to expected

experimental accuracy of the void measurements.

4.3 Pressure drops

4.3.1 Jnir£ducU£n_-

A series of pressure drop measurements has been performed

with 8ingle-phase flow as well as two-phase flow. For single

phase flow (liquid) a broad range of Re-numbers was covered

by extending the investigation from operating temperatures and

down to room temperatures.

The test section was provided with pressure taps for rela-

tively detailed pressure drop measurements. The positions

of the pressure taps (4 mm dia. holes), numbered from P10

to P23 are given in Figure 2. P10 is located before the

inlet and P23 in the riser about 1.3m above the top of the

bundle. Due to special circumstances, the pressure at P23

was measured within the flow by the use of a plate type

pick-up.

Prototype reactor spacers were of Marviken typo G (as for

FT-36a). A turbine flow meter and an impedance void gauge

were present in the riser of the test section.

The most significant feature of PT-36b compared to the pre-

ceding test section PT-36a (2),is the nonuniform radial

heat flux distribution. Another important difference bet-

ween PT-36b and FT-36a as to pressure drop, is the design of

the electrical connections of the heater rods.

The general ranges covered for the different loop parameters

are tabulated in Chapter 3. The results in detail are pre-

viously reported (18).

Some typical "loop-property-data" as those of inlet and

exit of the bundle,are included here as well, since these

are of interest for natural circulation calculations.

4 • 3 • 2

The loss coefficient obtained from (P10 - P11) shows the

behaviour of the inlet (Pig. 20a) • The independency of Re-

number is just as for the previous test section FT-36a,

but the mean value of k. , +»2.5 obtained now,is some 4$

lower.

The single-phase pressure drop for the channel including

spacers was measured from three sections,(P12 - P15) »

(P15 - P18) and (P18 - P21). These yielded very nearly

the same coefficients (Fig. 20 b).

There were also three pieces of test-section for measure-

ment of losses excluding spacers, but unfortunately, two

of these had faulty pressure t&ya. Friction factors ob-

tained from the stretch (P20 - P21) is plotted on Fig. 20c

As for FT-36a* the formula

f = 0.2 Re ~°'2 (4.3.2a)

fits the data very well for Re < 10^, but for higher

Reynolds numbers it underestimates somewhat.

The single-phase coefficients obtained for spacers alone,

using formula (4.3.2a) for bundle alone, is plotted on

Fig. 21 a. Since the above formula is somewhat in error,

the results given in Fig 21 a,are slightly too high in

the range above R >1O*?. Thus also, the spacer coefficient

has a stronger Reynolds no.- dependance than shown in

this figure. The three symbols used in Fig.21a represents

the three stretches over which the total single phase

pressure drop was measured.

A best mean value of the spacer loss coefficient for

FT-36b is assumed to be

ksp . 0.53 (R. >O.5.1O5) (4.3.2b)

The spaoer coefficient for FT-36a »jas found to

be O.58 for the very same design. Although one is aware

of some uncertainty in the present data, the results for

FT~36a-spacers are believed to be high as well as being

based on data with more scatter than the present ones.

For the same spacer design to a six rod bundle (FT-6b),

the spacer loss coefficient was 0.50, the accuracy of

which is believed to be about as for the present (i)#

One should expect a dependency of the spacer losses on

the bundle size (rod no.) (Refs.1,19,20) but the difference

from O.5O to 0.53 for the 6-rod and 36-rod bundles,

respectively, is very small compared to the accuracy in-

volved.

In Fig. 21b the pressure loss coefficient for the test

section outlet, k Ä Y, is tabulated and plotted versus

Re-number.At Re = 2 • 1(r the outlet pressure loss was

found to be about 1.0 velocity head* This value includes

wall friction, outlet spaoer losses (k £i 0*53)»sp

looses due to electrical cables and expansion losses

(pressure recovery and swirl losses). To check the influ-

ence of electromagnetic forces on the cables extending

from the top end of the heater rods, some measurements

were taken later on (x's on Fig.21b). One does observe some

difference from the first set of data, which was obtained

before power was applied (i.e. before settling of cables).

Comparing the data obtained with the test sections FT-36a and

FT-36b, one must note that the electrical connections of

heater rods on FT-36b, caused an additional outlet rest-

riot ion. The additional pressure loss coefficient for the

test eeotion outlet, due to electrical cables on FT-36b,

is 0.36 v,h, at He * 2 • io5. As the test section FT-36b

in addition was equipped with outlet instrumentation, the

total additional pressure loss coefficient compared to

FT-36a, will be the sum of O.36 and the pressure loss

coefficient for the outlet instrumentation. At Re » 2 • 10*

this makes O.36 + O.63 = 0.99 velooity heads (excluding

tube friction and separator losses). NB. In calculations

one must be aware of the different 2-phase characteristics

of the losses (i.e. different 0 - values).

The pressure loss coefficient for the outlet instrumenta-

tion, consisting of an impedance void gauge and a turbine

flow meter, is shown in Pig.21c. The instruments were of

the same type as for the instrumented boiling channels

of the Marviken reactor. The pressure loss coefficient,

shown in Fi^.21c involves contraction and wall-friction

for the instruments. The general experience with these

instruments has been presented in a separate report (4)*

A riser, intended to simulate the steam separator of a

Marviken boiling channel, was fitted to the test section.

The separator design was a tube with a perforated part

(Fig. 2). The separator characteristics shown on Fig. 22,

are based on the pressure drop through the perforation

at the lower end of this. The very strong influence of Reynolds

number is due to the change in water level in the separator.

4 • 3 • 3 jPwo-j haSJJ j^res;Sure—d£O£s_

The two-phase pressure drop data have been evaluated by

the use of the computer program TRYCK II (21).

Two-phase friction losses were obtained by subtracting

gravity - and momentum pressure drops from the total.

For nearly all cases, void data (12) were had from

measurements run parallelly with pressure drop measure-

ments* The two-phase friction multiplier, 02, has been

calculated using the single-phase data discussed in the

previous section.

In Pig. 23 is plotted a typical axial distribution of

pressure drops and void. The two-phase multiplier for a

smooth part of rod bundle (P20 - P21) at 30, 50 and 70

bars is shown in Pig. 24. The statistics of the different

flow groups are weak for 30 and 70 bars, but it seems clear

that the mass flow dependence of the two-phase friction

multiplier reduces strongly with increasing pressure. The

Martinelli-Nelson (23) and the Becker (22) correlations are

included in the plots for comparison.

As to spacers, earlier measurements on 3- and 6-rod clus-

ters at the Studsvik and ASEA laboratories (20,1).

indicated that the two-phase multiplier for the spacers

was very well correlated by the simple formula based on

the homogeneous flow model (23)»

To test the validity of the two-phase multiplier based on

the homogeneous flow model, one may use this to evaluate

the multiplier for the cluster itself. The result of this

is shown in Pig.25» where the calculated two-phase multi-

plier for the cluster and the Martinelli-Nelson correla-

tion have been plotted for 30, 50 and 70 bars. The best-

eye-fit curves for different mass flow in Pig. 25

demonstrates the same trends as the best-eye-fit curves

for the smooth part (P20 - P21) in Pig.24. The results

of these two calculations are compared for two mass flows

at 50 bars in Pig. 28a. Due to the small pressure drop

at low mass flow, one will expect the greatest discrepancy

between the two calculations at G %500 kg/m s. At this

mass flow the calculation using the homogeneous flow model

gives about 20$ lower value of 2

The gradients of the best-eye-fit curves at G«500 kg/m2 s

are nearly equal, while this is not the case at G»2000

kg/m s. For the calculation of the smooth part, the

two-phase multiplier shows a rather weak steam quality

dependence. This is probably due to inaccuracies in the

few measurements on which the best-eye-fit curve at

G »2000 kg/m2 is based (see Fig^4). However, the £ssump^

i ionjof jthe

In Pig. 26 the two-phase multiplier for the test section

outlet including one spacer, cables and expansion, is

shown for 30, 50 and 70 bars and compared to the Marti-

nelli-Nelson correlation as well as to the 0 based on

the homogeneous model. The outlet is seen to fall bet-

ween the two correlations. Furthermore, no mass flow de-

pendence of the two-phase multiplier is seen.

The two-phase friction multiplier at 30, 50 and 70 bars

for the outlet instrumentation consisting of an impedance

void gauge and a turbine flow meter, is shown in Fig. 27.

The multiplier based on the homogeneous flow model seems

to take care of the pressure dependence. Although the

number of points are few and there is some scatter, there

seems to be a definite trend of mass flow dependence of

the two-phase multiplier.

Concerning both the test section outlet and the instru-

mentation, one must note, however, that for void in these

evaluations, the a - x characteristics of the bundle has

been used. Compared to void from turbine (Fig. 12)

and y -void measurements at exit of F-36a (2), the bundle

void is somewhat lower.

Difficulties were had in obtaining two-phase data for the

separator. The use of a different DP-cell during the

next experiments (FT-36o) is hoped to yield consistent

data.

4.3*4

In Fig. 28b the mass flow dependence as obtained from the

present 50 bars-experiments,is compared to the mass-flow-

corrected MartineHi-Nelson correlation reported in Ref. 24

Although the present data are too few to allow for quanti-

tative conclusions, it is clear that the correlation

generally overestimates the mass flow dependence of the

two-phase friction multiplier, as compared to the present

results on PT-36 b, in particular at high rates of flow.

4«4 Dynamic characteristics

dynamic measurements have been performed to predict the

behaviour of the Marviken reactor with respect to hydro-

dynamic characteristics, to check dynamic models and to

obtain experience on in-core instrumentation. The measure-

ments have mainly been performed at loop conditions close

to those expected for the Marviken reactor. Studies of

the influence of different parameters on the hydrodynamio

characteristics have also been carried out. A summing up

of the measurements is given below; for more detailed data

is referred to Ref. 26.

To obtain experimental data on the detailed hydrodynamic

behaviour ,transfer functions from heating power to diffe-

rent loop variables have been measured. General informa-

tion on the hydrodynamics from inverse noise extrapola-

tions and recording of loop variables close to the stabi-

lity limit,is given in Section 4*1•

As was found in earlier experiments ( 1,2),the mass velocity

and exit void signals were quite noisy. The time responses

were therefore considered unsuitable to characterize the

system apart from giving information on the noise level.

The dynamic measurements were thus analyzed with respect

to frequency to minimize the influence of noise.

Transfer functions were obtained by introducing square

wave- and pseudorandom perturbations (27,28) in heating

power and recording the responses in mass velocity and

exit void,primarily. Square wave perturbations of diffe-

rent amplitude were introduced to test the linearity of

the system. A few responses in inlet temperature and

system pressure were also recorded. It was found that

these responses were too small to be significant in this

type of etudies» at least at higher frequencies.

The type of pseudorandom perturbations used are binary

and periodic with a Fourier spectrum of limited bandwidth.

Bjy using this type of perturbations, the transfer functions

are obtained for several frequencies simultaneously. Time

is saved and all values of the transfer functions are ob-

tained under fixed loop conditions. A correlation tech-

nique was applied in the analysis (29>30) .Small perturba-

tions could thus be used with satisfactory accuracy in the

measurements also when the noise level was high.

The data collecting and recording system used during the

measurements,is built up around the data acquisition unit

RAMSES (5) • Recordings were performed on paper tape and

pen recorder. Phe generation of the perturbation function

was controlled by RAMSES. A turbine flow meter and an im-

pedance void gauge (4) were used for exit void measure-

ments, and the venturi unit (Fig. 1 ) with a fast respond-

ing DP-cell (2) has been used for dynamic mass flow measure-

ments.

4.4*2 Results,

Square wave perturbations of different amplitude and fre-

quency were introduced at some loop conditions to test

the linearity of the system. For power modulations of less

than 4 %9 no nonlinear behaviour could be observed.

At high frequencies a correction should be applied for

the dynamics of the heated tubes if the heat flux to the

water is considered, as the heat flux is somewhat atten-

uated and delayed with respect to the electric power.

Due to the thin walled rods, however, the attenuation

and the phase lag are only approximately 1 dB and 10

degrees, respectively, at a frequency of 1 c/s and thus

of the same order as the experimental accuracy. On the

other hanA, these values are small compared to the corre-

sponding values for the transfer function of nuclear power

to heat flux in a real reactor channel.

In Figs. 29 - 31 are presented transfer functions power-

to-mass velocity and power-to-exit void fraction ob-

tained at conditions close to those expected in the

Marviken reactor» p « 49»5 bars, A$ . « 3°C, k. •sub in

13 v.h., Q « 3 MW and 4.5 MW. The effect of changes

in one of those parameters has been investigated»

The strongly destabilizing effect of decreasing the

pressure from 50 to 30 bars is demonstrated in Pig.

29a, showing measurements at a power level of 3 MW.

The resonance peak in the mass velocity gain is seen

to increase from 7 dB to 18 dB, while the resonance

frequency remains at approximately the same value,

0.45 c/s. Por comparison, it may be mentioned that the

stability limits of the two cases were 6.5 MW and 4-2

MW, respectively, according to the noise analysis dis-

cussed in Section 4*1• The destabilizing effect of de-

creasing the pressure is due to the fact that the diffe-

rence between steam- and water specific volumes increases

with decreasing pressure.

Also for the exit void (Fig. 29b), a sharp resonance is

observed at about 0.45 c/s in the case of 30 bars, indi-

cating a strong interaction between void and mass velocity.

A weak resonance is found also at a frequency of about

0.8 c/s.

As expected, the sharp resonances observed in the gain

of mass velocity as well as of exit void, coincide with

a value of 180° of the phase. A rapid increase in phase

* typical for power-to-void transfer functions, is

found at higher frequencies in Pig. 29b. It should be noted

that the scale of the power-to-void phase diagrams has not

been extended beyond 360° because the phase is uncertain

to a multiple of 360° at high frequencies.

The influence of subcooling on the transfer functions is

illustrated in Pigs. 30a and 30b (^in«13 v.h., p«50 bar,

Q«4.5 MW). The subcooling is changed from 3 C to 23 C.

If the peak value of the ma3S velocity gain can be re-

garded as an inverse measure of tho degree of stability,

the curves of Pig. 30a indicate a weak stability minimum

at a subcooling of about 14°C. This seems to be in fair

agreement with the tendencies of the stability limits

found from inverse noise extrapolations. The resonance

frequency is decreased from about 0.5 c/s to about 0.3 c/s

when the subcooling is increased from 3 C to 23 C •

In Pig. 31 a comparison is made between power-to-mass

velocity transfer functions obtained for PT-36a and

PT-36b at similar conditions. The peak value of PT-36a

is significantly lower than for the two cases of FT-36b

«2°C and c*6°C). The lower stability of FT-3éb

is probably due to the additional outlet restriction

("1.0 v.h.), mainly. This restriction makes the loop less

stable because the outlet pressure drop will be more

sensitive to void variations.

Transfer functions measured at a loop condition close

to instability, are shown in Pig. 32a and 32b. The con-

dition was: Q = 3.33 MW, k. » 4.6 v.h., p * 30 bars andA^sub * 2 #7° c # T h e extrapolated stability limit was found

to be 3*4 MiV. For the transfer function measurements,

power modulations of about 1 $ and 2 $ were introduced,

but no significant influence from nonlinearities was

found. Nor did responses to square wave perturbations

with power modulations up to 3 $ show any significant

nonlinearities. Sanborn recordings (fig. 32c) showed

that the mass velocity modulation was as large as 50 $.

The transfer functions power-to-mass velocity and power-

to-exit void fraction show peak gain factors of 45 and

2 respectively. The result from the measurement suggests

that even higher gain factors could have been obtained

for a slight change in frequency.

The calibration of the impedance void gauge for the dyna-

mic measurements was performed statically by means of the

turbine flow meter at channel exit (4)* In order to take

into account the time variation of water conductivity,

this calibration was performed a short time before or

after the dynamic measurements.

A dynamic method of calibration of the void gauge was

also tried. This was based upon measurements of the trans-

fer functions down to sufficiently low frequencies where

the gain attains a constant, static value. Such calibra-

tions are performed simultaneously with the measurements,

thus increasing the accuracy and in some oases reducing

the experimental time. A maximum difference between sen-

sitivity factors obtained by use of the static and dynamic

methods, respectively, was found to be 2 dB, which is of

the same order as the estimated accuracy of the measure-

ments •

4»5 Steady etate turnout

In all, 38 steady state forced circulation burnout measurements

were carried out at the pressures of 30, 50, 70 and 87 bars.

For all the runs, burnout occurred at the end of the heated

seotion and among the six of the 18 outer rods, which are

shown in Fig. 3* Visual inspection of the test section after

completion of the measurements did not reveal whether burnout

occurred on the side of the rods facing the outer shroud or

the side facing the interior of the bundle.

The experimental results are given in Table 5 (p4i) (31 )*

For comparison, the predicted burnout conditions, employing

the Becker rod bundle correlation (32) are also included in

the table* In Fig. 33 the data are presented in a plot of

burnout steam quality versus the burnout parameter

10V(° * <I/A)« It should be pointed out that this repre-

sentation is based on the local burnout hypothesis, where

the average flow parameters at the burnout position are used.

One observes that the highest burnout heat fluxes are obtained

at 50 and 70 bars, while the 30 and 87 bars measurements

indicate somewhat lower values. Further, for a given pressure,

the effects of inlet subcooling are negligible and the effect

of mass velocity seems to be accounted for by the relationship

q/A ~ G , which applies to round tubes in wide ranges of

variables (33).

However, if the system describing parameters are used, a

somewhat different picture is obtained. In this case the

burnout heat flux is given by the function,

( q A ) B 0 - f (p, G, A^ s u b,L, T) , geometry, flux distribution).

For a test seotion with given flux distribution and geometry,

this function reduces to

which for fixed values of A^^and p permits to present the data

in plots ef (qA)gQ versus the Base velocity 0. In Fig* 34 the

present data are plotted in this Banner for the case of 3 C

subcooling. One observes new that the burnout heat flux increases

with increasing mass velocity, whioh is in contrast to the

previously given relationship from the BO.-parameter.

In Fig. 3& the burnout heat flux is plotted versus the pressure for

the nass velocities of 600 and 1000 kg/a* s. For 6 - 1000 kg/m2 8

the highest burnout heat flux is obtained at 30 bars, and then

the burnout heat flux decreases with increasing pressure, while

in the other case the optimum burnout conditions are obtained at

30 bars. Reverting to the local hypothesis, the optimum burnout

conditions were obtained at 50 and 70 bar. The reason for this

apparent contradiction is found by considering the latent heat

of vaporization, whioh decrease» with increasing pressure.

A comparison between the measured and predicted burnout heat

fluxes is shown in Fig. 36. The 50, 70 and 87 bars data are

0-16 per cent low compared to the predictions and the 30 bars

data are 12-18 per cent low. The errors increase with increasing

heat flux»

During a previous phase of the present study, a uniformly heated

36-red bundle ef identical geometry was investigated. 14 burnout

measurements were obtained at a pressure ef 30 bars. In Fig. 37

the data for uniform heating are compared to the present data

on the basis of predicted heat fluxes (Table 3 , Ref8. 2 and 32).

One observes that the uniform heat flux data are 14 to 24 per

cent low compared to the predictions, while a significantly

better agreement is found in the case with a radial flux varia-

tion. In Ref. 2 it was suggested that the discrepancy for the

thermal load in the inner sub-channel of the bundle was high

by a factor of 1 • 33 compared to the average value for the whole

bundle, and to the presence of the unheated center rod in the

inner sub-channel.

For the present bundle the thermal load of the inner sub-ohannel

is reduced to 0*98, because of tha flux depression at the center

of the bundle.

Our previous suggestion for the uniformly heated rod bundle

is therefore supported by the present measurements. It is

also of importance to notice that burnout in the present

oase occurred on six of the 18 outer rods, while in the

uniformly heated bundle, burnout occurred on the inner six

rods.

However, comparing the two bundles and using the system de-

scribing parameters, one finds that the total burnout powers

are almost identical for the two cases as demonstrated in

Pig. 38.

Table 5

Measured static burnout conditions in FT 56b

compared to predictions by the Becker correlation

4051014051024051054051044051054O51U64051074051084051094051104O5IH4051124051154051144051154051164051174051184051194051204051214051224OJ.I254051244051254051264051274051284051294051504051514051524051554051M405155405156405157405158

P

50.250.550.550.049.869.269.269.269.569.269.569.26P.769.26y.269.287.587.587.587-587-587.587.550.551.850.549.850.150.150.150.250.250.250.050.250.250.250.0

mib rDUU Vj

8.19.48.09.47.95.52.85.55.85.55.52.5

25.521.522.524.64.02.85.15.02.92.02.05.25.65.55.0

25.025.025.524.221.55.52.6

. 5.15.75.72.6

G 2kg/m. s

4754675*8712796556712862

1012121714451790497756849608564688852

115S159817651600

587727974

1095I 590! 755! 420! 541I 698; 586I 512: 740: 886! 1027! 1140t

Measuredburnout

q/A)maz

V/em

96.597.0

108,0115.0119.592.5

102.2107.4112.5118.8125.7127.199.4

115.1125.5110.485.891.597.4

104.9110.9125.7119.5100.5110.0119.0122.0112.8122.8

95.5106.011Ö.597.790.6

109.0115.5122.5125.0

values

*B0#

47.648.541.757.054.645.457.452.128.424.921.818.144.754.451.240.242.457.551.825.521.819.520.841.556.629.126.559.754.44Ö.941.45^.956.759.151.826.42^.824.1

Predictedburnout •

(q/A)mai

W/om2

98.097.5

111.9125.2129.2

97.5110.1120.0127.9156.2145.4151.5101.5122.4151.5112.788.797.1

106.7118.5125.9152.7128.9108.6120.7157.5144.011^.2151.2

96.4115.0124.5112.6105.8128.2158.7147.6152.7

values

*B0

48.548.745.859.957.645.740.456.052.528.725.321.745.536.935.440.944.039.835.129.024.921.023.044.840.233.931.542.2

. 37.849.444.240.242.444.937.734.231.429.5

in q/A

*

- 1.5- 0.5- 3.5- 6 . 7- 7.5- 5.1- 7.2-IO.5-12.2-12.8-13.7-16.0- 1.9- 6.0- 5 . 9- 2.0- 3.5- 6.0- 8.7-11.3-11.9- 6.8- 7.3- 7.5- 8.9-15.5-15.3- 5.4- 6.4- 1.1- 6.2- 5.0-13.2-12.7-15.0-16.7-17.0-18.1

5. COMPARISON WITH STEALY STATE AND DYNAMIC MODELS

Ae in the case of FT-36a,the experiments on the PT-36b geometry

have given a large number of data which are useful in the eva-

luation of the existing correlations and computational programs.

Such evaluations are done by calculating the steady etate and

dynamic performance of the test section and the loop for some

of the experimental conditions and thai comparing the calculated

results with the actual data* Similar comparsions were made with

the results of the FT-36a experiments which were reported pre-

viously (2).

For the sake of completeness the computation programs available

in the Danish, Norwegian and Swedish institutes have been used

in parallel.

These programs are the following.

BOSFLOW from the Danish Atomic Energy Commission, Denmark (35)

for steady state calculations.

HYDRO II from AB Atomenergi, Sweden (36,37)

for steady state and transient calculations.

RAMONA from Institutt for Atomenergi, Norway (38)

for steady state and transient calculations.

These programs are prepared for solving one-dimensional time-

dependent hydrodynamic equations. However, the BOSFLOW code does

not include the solution of the time dependent equations. For

the steady state calculations these programs are very similar

and the only difference between them may occur in the options

of the correlations for void calculation.

In the following calculations BOSFLOW has used Bankoff-Jones

correlation with a modified constant for fitting the void data

from FRIGG-experiments (39).

HYDRO calcuaitions are made by using the original Bankoff-Jones

correlation (24).

RAMONA uses an empirical correlation obtained from FRIGG experi-ments (16)

For void calculations in subcooled boiling regions BOSFLOV

and HYDRO use Bowring'e model (40) while RAMDNA has a different

modal (38).

For the frictioral pressure drop in two-phase flow through

the straight parts of the channels all the three programs use

Becker's correlation (22).

These programs have been used for the following calculations

for comparison with the data.

A. Variation of mass velocity with the input power in opera-

tion with natural circulation.

B. The limit of stability or critical power level.

C. Transfer function between relative changes in power and mass

velocity.

D. Axial variation of the average void fraction in the channel.

In addition to these programs the HAMBO code for subchannel ana-

lysis (41) vas used for comparison with some data both in Denmark

and Sweden. This program was used in its original (standard)

form in Sweden, while in the Danish version of HANBO there has

been an adjustment of the Bankoff-Jones slip correlation to the

FRIGG void data (as in the case of BOSFLOW). In addition to this

adjustnmt Becker's burnout correlation was included in the pro-

gram.

HANBO was used to calculate

E. Radial and axial void distribution in the test section

F. Burnout calculation in various subchannels

5,1 Variation of mass velocity with heat flux in natural circu-

lation»

The experimental data obtained with FT-36b include several trends

of the variations of G with Q under different conditions. These

include pressures from 50 to 70 bars and a variety of inlet sub-

cooling and throttling coefficients* For a common test of the

above mentioned programs one case at each operating pressure of

30, 50 and 70 bars was selected.

The inlet subcoolings and the throttling coefficients were al-

most identical in these cases as indicated on Figs. 39-41. The

main difference was in pressure.

The outlet throttling in the FT-36b test section was consider-

able as compared to the FT-36a geometry. As explained before,

the additional resistance at the outlet was due to the elec-

trical leads and the void measuring instruments* This thrott-

ling has been measured under single phase flow conditions and

the net difference between FT-36a was found to be about one

velocity head (based on the flow area within the heated chan-

nel).

With these data the mass velocities in natural circulation were

calculated as a function of the total channel power. The results

are shown in Figs. 39*41*

As seen in the figures the results of calculations with BOSFLOW

and RAMONA are almost identical while the calculations with HY-

DRO II are different and show higher mass velocities. The reason

for this descrepancy is the different values of the two-phase

pressure drop multiplier, which are used for spacers and the out-

let throttling.

In tha case of steady state calculations by HYDRO the local two-

phase multiplier was calculated according to the homogeneous flow

model which gives

But in BOSFLOW and RAMONA one has used an average value of the

local multipliers, vftiich were obtained for tiie spacers in FT-36b

when the Martinelli-Nelson correlation (25) was applied to correct

for the pressure drop caused by the smooth parts of the cluster,

as discussed in Ref. 18. These multipliers had a stronger depen-

d«noe on steam quality and could, on the average be expressed by

the following relation

f - 1 + 1.4 (-jr- 1) x (5#ib)

This relation gives higher pressure drops at spaoeras and at

the outlet and thereby the calculated mass velocities turn out

to be lover as compared to HYDRO calculations»

As seen in Figs. 39-411 there are som discrepancies between

the measured and calculated mass velocities. The largest diffe-

rence is about 10 # of the measured quantities.

2

In a series of calcualtions by HYDRO II the usual form of <J> ac-

cording to the homogeneous flow model was used for the spacers

and the outlet throttling, but the outlet throttling was taken

to be 4*0 velocity heads instead of 1.06, which was used in

the other calcualiians. The mass velocities computed with this

outlet throttling are compared with the experimental data on

Pig. 42.

These calculations show considerably better agreement with the

data. A plausible explanation for the existence of a higher out-

let throttling in reality may be the increased resistance of the

steam-water separator in two-phase flow.

In the description of the experimental conditions for preparing

the input data for these programs the water level inside the per-

forated steam-water separator has to be taken as a constant. But

in reality it will be variable and specially in the case of two-

phase flow there will be a level rise inside this component which

will depend on the steam quality, flow rate and pressure. The cal-

culation of this variable level is not included in the present

programs. The arbitrary increase of the outlet throttling in the

HYDRO calculations has partially (in some cases totally) eli-

minated the difference between calculated and measured values.

This may be explained as a compensation for the level rise in

the separator.

In all the subsequent calculations by HYDRO which are presented

in this report the input data were matched to those used in BOS-

FLOW and RAMONA in order to obtain a meaningful comparison.

5.2 Limit of stability

Stability limits have been calculated by the two programs HYDRO

(56, 37) and RAMONA (58) for the following series of experiments.

Table 6a

Series

1

2

3

Run no.

401156-401148

401257-4012?0

401162-401173

Pbar

49.8

29.8

49.9

k.in

v.h

15.7

15.5

5.1

The limits have been obtained by stepping up the power and cal-

culating the damping coefficient for the oscillation in inlet ve-

locity. The stability limits are found by interpolating to zero

damping coefficient.

Table 6b

Series

1

2

3

Measuredlimit MW

6.05

4.20

iCalculated by HYDROLimit MW Deviation $>

6.75 + 11.2

4.67 + 11.4

6.57 + 11.0

Calculated by RAMONALimit MW Deviation $

5.91 -2.4

3.94 -6.1

5.56 -4.0

The results from HYDRO are generally 11 fo too high. The reason

might be the Bankoff-Jones correlation used for void calcula-

tion. If a correct correlation is applied an even better pre-

diction might be expected.

The RAMONA results are generally 5 °/o too low, which must be cha-

racterized as satisfactory.

It may be concluded that dynamic programs oi this type are capa-

ble of predicting hydraulic stability limits with a reasonable

degree of accuracy ae long as the steady state correlations used

for void and friction are in agreement with the measured steadystate values.

5*3 Transfer functions

As described before the transfer functions from heating power

to exit void fraction have been measured.

One series of measurements has been compared with calculations

obtained with the two programs HYDRO and RAMON A.

The comparisons include runs no. 462004,462013 and 462019,

where transfer functions from heating power to inlet veloci-

ty were established.

The operating conditions were:

p « 50 bars

Q » 5000 kW

G = 820 kg/m2e

AS , = 2.0 °Csub

Four transfer functions have been calculated:

1. HYDRO with constant loop pressure and step pertubation in

power input

2. RAMONA with constant loop pressure and step perturbation in

power input

3. RAMONA with constant loop pressure and several distinct si-

nusoidal perturbations in power input

4. RAMONA with variable loop pressure and step perturbation in

power input

The results are plotted in Fig. 43*

The results illustrate the difficulties encountered in compa^

ring dynamic models and experiments. The following may be empha-

sized:

9£feots_of,

In the range of very low frequencies the HYDRO calculations

show a better agreement with the data while the RAMONA cal-

culations with constant pressure (as in HYDRO) yield higher

gains.

b.

c.

Considering the fact that in the actual runs the pressure

has not been free of fluctuations, (as will be explained lat ir)

complementary calculations were made with RAMDNA allowing

for pressure fluctuations.'Phese gave better agreement with

the data, especially in the low frequency range.

Since the HYDRO calculations were performed at constant pre-

ssure, it may be concluded that the apparent agreement with

the data at low frequencies must be an incident caused by the

use of the original Bankoff-Jones slip correlation. In the

steady state calculations by HYDRO this correlation gives lo-

wer void fractions than the measured data (see 5.4). In o-

ther words, a different slip correlation giving better agree-

ment with the measured void data yields a worse agreement be-

tween the calculated and measured transfer functions at low

frequency if the pressure fluctuations axe not taken into con-

sideration.

Generally both HYDRO and RAMONA calculate transfer functior* «?n

the bases of a step perturbation due to the short samplip_ time

needed. In the experiments, however, several pseudorandom per-

turbations of limited band width have been used.

In Pig. 43 case 2 and 3, a considerable difference in transfer

function is observed between step response and single sinusoidal

perturbations. The difference migit be due to the constantly de-

creasing "level of information" with increasing frequency for

a step response. Another explanation might be crosscoupling ef-

fects through the nonlinear system.

The correct perturbation in such a comparison should preferably

be the same as used experimentally. Due to the oscillating "in-

formation level" as a function of frequrncy, care should be ta-

ken to calculate gidn only at the "information peaks".

and RAMONA ultilize the same numerical technique for cal-

culating transfer functions where perturbations and responses

are Fourier transformed by means of a trapezoidal integration ru-

tine.

Depending on the sampling period the numerical error in-

creases with increasing frequency. This is dearly the re-

son for HYDRO'S "secondary resonance peaks".

d. Influence ofj33£stem jgressure^

The FRIGG loop is equipped with a fairly large steam dome

coupled to a large spray condenser. The characteristics of

the condenser are not reported as it has been assumed that

a constant system pressure is a good approximation.

In case 4 the system volume of dome and condenser are in-

cluded in the calculations by assuming condensation rate

which 1B a function of the system pressure as in a Laval

nozzle. The influence is clearly seen, indicating the im-

portance of including the spray-condenser characteristics.

This effect may possibly explain the somewhat astonishing

constant experimental gain obtained at the lower frequen-

cies. One should keep in mind that the dynamic gain obser-

ved at low frequencies for these experiments may bs diffe-

rent from the steady state gain as obtained from the flow-

power curves.

e. Influence of\inlet_sub£oolin£

The time delay from the introduction of feed water to the

heated channel inlet is 30 sec. For the step response cal-

culations, no influence of inlet suboooling will reach the

channel during the sampled transients.

If a time delay is used for downcomer representation the

influence of suboooling might be substantial. The physical-

ly correct representation, however, due to the turbulent

mixing, seems to be a series of time constants corresponding

to section lengths of a few hydraulic diameters. In that

case, the long downcomer in the FRIGG loop would filter out

mostly all influence of subcooling for the frequency rang»

of interest. ,

It may be concluded that the dynamic models HYDRO and RAMONA

are capable of representing a hydraulic channel with a fair

degree of accuracy, if ail the relevant physical phenomena

are taken into consideration.

5.4 Void fractions along the heated channel

The void distribution along the heated channel ha_» been cal-

culated with BOSFLOW, RAMONA and HAMBO based on the experi-

mental mass flow for six cases as shown in Fig. 44 - 46.

The resulting curves are really a check on the slip corre-

lations used for subcooled and bulk boiling.

In the subcooled region the RAMONA model and Bowrings sub-

cooled model give nearly the same results.

For the bulk boiling void the RAMONA and BOSFLOW results are

again fairly similar. The somewhat better result s from RAMONA

are due io the more extensive slip model used.

The HAMBC results, however, are generally about 7 <fo too low

due to the high slip ratios obtained from the original Bank-

off-Jones correlation.

Since HYDRO calculations with Bankoff-Jones correlation wo-

uld yield identical void fractions as those obtained with

HAMBO (mixed flow calculations) the latter values are shown

on Figs. 45 and 46 and are marked by HAMBO(s).

5»5 Subchannel analysis

The extensive series of axial and radial measurements in the

FRIGG experiments together with burnout measurements where

also the location of the burnout point is recorded offer a

unique possibility for subchannel investigations.

As a base for the present subchannel investigations is used

the thermohydraulic subchannel programme HAMBO, which is de-

veloped by Dr. R Bowring and associates at UKAEA, Winfrith

(41).

J I

The programme has in the • * ja part been used in a similar

manner as in the earlier- JUGG reports (1, 2). There is,

however, some difference iuad the approach in a later investi-

gation (39) has been br; xi upon the following idea.

The HAMBO programme is first used in a "mixed flow" option,

which essentially is a c. ie subchannel calculation* A para-

meter study is performed in order to obtain the best possi-

ble agreement between void calculation and measurement with

respect to the axial void distribution. In the HAMBO void

investigation of FT 36a and b was the "best" agreement ob-

tained simply by modifying the standard Bankoff-Jones slip

correlation in such a manner that the constant 0.71 in this

formula was replaced by a massflow dependent relation (39).

0.9086 GG + 123

The result was that the mean void along the channels could

be reproduced within approximately 4 void percent for a spe-

cific mas8flow above about 700 kg/m s.

Based upon the fitted mean void the general mixing scaling

factor M in the HAMBO programme was adjusted to give the best

possible agreement with the subchannel void. The result was

M « 2 to 3 for FT 36b

M « 3 to 4 for FP 36a

Three characteristic runs (413147» 413109» 413116) are se-

lected for this report and the result of the calculations

and the experiments is presented in Figs. 47 -49* These cal-

culations are, however, based upon a mixing factor M • 1.

Even better agreement between calculations and experiments

could have been obtained by using M - 2. The value M - 1

was used in order to make possible a direct comparison be-

tween this report and the results presented in Ref. 2 for

the FT 36a experiments*

The curves marked S and D in Figs. 47 - 49 vtvr to HAMBO

calculations with respectively the Bankoff-Jonet formula

and the modified version which it described above*

It is seen that the agreement in general between calcula-

tions and measurements is satisfactory, specially when the

uncertainty in the void measurements is taken into account.

The main goal with a subchannel programme is, however, to

predict the onset of burnout* In Fig* 30 is plotted as fun-

ction of flow the difference ($) between the HAMBO prediction

(using the Becker burnout formula) and all the measured burn-

out points for the FT 56b element.

The error is within approximately - 10 $, which is an impor-

tant improvement compared to a non subchannel prediction as

e.g. given in Table 5 * where the error is within 0 to 18 $.

A similar subchannel investigation has been done for the FT

36a testsection with uniform heat flux distribution and idle

error was here within approximately - 5 % compared to an er-

ror of 14 to 24 % in the rod bundle correlation (2,32).

- 53 -

6. CONCLUSIONS WITH SPECIAL REFERENCE TO THE

MARVIKEN REACTOR

6.1 General

As already mentioned, FT-36b was the seoond full-scale

test section of the out-of-pile studies en a Ihrviken

boiling channel* The first full-scale experiments (2)

were performed on a rod bundle having all uniform power

distribution* The present bundle was manufactured te

give a radial power peaking, while the next bundle repre-

senting the final step, is to have an axially as well

as radially nonuniform power distribution, both oorre-

sponding to expected reaotor conditions*

The present experiments deviate, from the reaotor con-

ditions in respects which appear to be of great impor-

tance when trying to predict accurately the power margins*

These concern predictions of stability limits as well

as burnout limits of the reaotor fuel elements* The radial

power distribution of the FT-36b-"bundle was determined at

and early stage* For this reason the chosen value of the

radial form factor (1*18) became appreciably greater than

present predictions for the reactor* First of all, this

was expected to influence the static burnout limit, but

due te different flew distributions within the bundle, te

seme extent also the hydrodynamio stability limit*

Secondly, the outlet restrictions of the experimental set

up were appreciably greater than in the reaotor case due

to outlet instruments and electrical power connections*

This primarily influenced the hydredynamic stability limit

which decrease* with increasing outlet throttling* An influence

on the burnout limit at steady flew conditions evidently

occurred through the reduced natural circulation mass velocity*

6.2 Comparison ef present experimental result» and Maryiken

operating conditions.

Despite the differences between the present experiments and

the conditions in Marviken, some valuable conclusions oould

be drawn fren the extensive test-results obtained* First of

all it is quite clear that burnout occurs without any pro-

ceeding oscillations at operating conditions corresponding

to the reactor case (e.g.Ad eub - 3 c,kin*13 v.h.)

Furthermore» the burnout power in natural circulation in

this case is practically identical to the value obtained in

forced circulation at the same flow rate.

In Fig*51a is shown the burnout power density and the extra-

polated stability limit as a function of inlet throttling.

As was expected, a rapid increase in stability limit and

a slight reduction in burnout power are obtained with in-

creasing inlet throttling. According to the figure, the

two power limitations coincide at an inlet throttling of

about 10 v.h.• However, both the stability limit and the

burnout power are expected to be somewhat higher in the

reactor case due to reduced outlet throttling and a smaller

radial form factor. It still would seem, however, that the

inlet throttling chosen in the Marviken reactor, is very

close to the optimum value*

On *ig. 51a the power density vs. inlet throttling is given

for constant inlet subcooling. Increasing the inlet thrott-

ling in the reactor, however, will have the secondary effect

of increasing the inlet suboooling. As is evident from Fig

this would tend to reduce the gain in stability limit when in-

creasing the inlet throttling, at least in the range of inlet

subcoolings of interest for the Marviken reactor. On the

other hand, an increase in subcooling improves the burnout perfor-

mance. The net effect of the increased inlet throttling on burnout

power, within the range considered, should be very small.

During the start-up of the Marviken reactor, the reactor

pressure will increase linearly with power above the pressure

of 12.5 baiB.As both burnout power and stability threshold

power is reduced when reduoing the pressure, the power margins

should be checked at various reactor power levels* On Fig.52

a comparison is made between the present experimental data

and the power variations in Marviken during start-up* Bearing

in mind the reduction of the stability limits in the experiment

(Section 6*1)» it seems that sufficient margins exist over the

JJ

whole start-up range.

On Fig. 53 the present natural circulation and static burn-

out curves are compared to the previous experiments on FT-

36a. There has been an appreciable redaction in channel mass

flow in FP-36b compared to that of FT-56a. This is mainly due

to the increase in outlet throttling. Besides, there is no evi-

dence that the natural circulation curve calculated for Mar-

viken, should be erroneous, Tha static burnout curve for JT-

36b deviates from the previous one by its slope. While in

IT-36a burnout indications were obtained on the rods of the

inner ring, burnout was obtained on the outer rods of IT-36b.

This is certainly a result of the change in power distribution,

although a convincing explanation of the change in the slope

of the burnout curve is not at hand. It is expected that the

data from the next test section will contribute to the under-

standing of this phenomenon»

In Ref. 2 it was mentioned that the heavy water in the reactor

would give rise to a higher mass velocity than in the experiment.

On the other hand, the outlet steam quality from the reactor

channel will be higfrer than in the experiment for the same po-

wer, due to the lower heat of vaporisation for heavy water. This

will tend to displace the burnout curve slightly towards lower

powers for the reactor case.

At flow rates of interest in Marviken, the internal power di-

stribution of FT-36b would reduce the burnout power compared

to the uniform distribution in PT-36a. It seems that for this

power distribution, the rod spacing of the bundle is not at an

optimum. However, the actual internal radial form factor is ex-

pected to give somewhat higher burnout powers. In the last step

of the full-scale experiments for the Marvikon reactor (5T-56c),

a final confirmation of the power limitations will be obtained.

7* GENHiAL CONCLUSIONS

In addition to the information of direct interest for the Mar-

viken reactor, as discussed in Chapter 6, the FP-36b experi-

ments have contributed significantly to the general knovledge

of the thermo-hydrodynamic behaviour of large fuel clusters

for boiling water reactors. As a result, at least partly, of

a more reliable test section design, a ouch broader range of

parameters could be investigated as compared with the FT-36a

experiments (2). On the other hand the new design introduced

an extra outlet restriction, further increased by the use of

cutlet instruments, which influenced the natural circulation

behaviour to such an extent that a possible influence of the

radial heat flux distribution was masked.

The results indicate,however, that the influence of the rad-

ial heat flux distribution on the natural circulation mass

velocity as well as the stability limit was small. This is

concluded from comparisons with the 6-rod tests (1), in which

the influence of outlet throttling was investigated. The re-

sults of the void and pressure drop measurements support this

conclusion»

The average void fraction was close to that obtained in the

earlier experiments (1, 2) in the quality range x&15 % At

higher qualities the FT-36b results were slightly lower fé3#)«

The radial void distributions showed an expected decrease in

the central regions. The accurary of the void measurements

was not affected significantly by the new test section de-

sign but the number of axial positions was reduced.

The pressure drop measurements sees to verify the

flow model for the spacers. A mass flow dependence not inclu-

ded in the normal Becker and Jtatinelli-Kelson correlations

(22, 2b), was found in the two-phase friction multiplier for

smooth parts of the duster. It must be concluded, however,

that an accurate separation of the different pressure drop

component i» difficult doe to the very small pressure drops

involved* More experiments are needed before firm conclusions

J\

can be drawn. Except for the outlet, the total pressure drop

was close to that of IT-36a at comparable conditions. The out-

let pressure drop» especially that of the steam separator»

must be paid still more attention, experimentally aa well as

analytically, because of its importance for the interpreta-

tion of the natural circulation steady statt and dynamic

surements.

The preliminary hydrodynamic calculations made for some of

the experimental cases, indicated that mass velocity, stabi-

lity limit and frequency response can be predicted by existing

models with reasonable accuracy. However, the results depend

on a successful matching of the steady state descriptions of

the void and pressure distributions. It is therefore necessary,

if such calculations are to be relied upon, that detailed a-

greement is obtained between calculated and measured void di-

stributions and pressure drops. In this respect more work has

to be done. Further it has been shown that not only the test

section but also the loop itself has to be carefully treated

in the dynamic calculations.

The HANBO program (41) was tested against some measured axial

and radial void distributions. Reasonable agreement was ob-

tained with a slightly modified version of the standard Bank-

off-Jones slip correlation (24) and a turbufent jnixing factor

M - 1,to 3.

Burnout calculations with this version of the HAMBO program,

using the Becker burnout correlation (52), indicated that sub-

channel analysis has a potential for improving the accuracy

of burnout predictions in multirod fuel elements as compared

with simple mixed flow calculations. It must be concluded,

however, that considerable improvements are still needed in

the methods for burnout prediction.

The interesting observation that the channel power at burnout

was approximately the same for FT-56b as for the uniformly hea-

ted i?-36a at comparable conditions, does not imply that the

radial heat flux distribution has no influence on burnout*

The fact that the burnout postion was changed fron the inner

rods in IT-36a to the peripheral rods in JT-36b suggests the

existenae of an optimum radial heat flux distribution giving

burnout on all rods at about the same tine. This assumption

is supported by the results for the third 36-rod cluster»

which will be presented in the next HtlGG-report.

Acknowledgements

The authors wish to thank Mr Jan Plinta at AB Atomenergi and

Mr Cnut Sundqvlst at AS3A-AT0W who initial ad this series of

experiments and have taken a very active part in the planning

of the measurements and the discussion of the results.

Thanks are also due to all those who helped in designing and

manufacturing of the experimental equipment and those who

ass-' tfc. in the operation of the loop and the instrumentation.

Nomenclature

Symbol

A

f

F

GdtyGH

k

kout

Definition

Heated surface (over L)

Friction factor liquid phase

Cross-sectional flow area

Mass velocity

Relative peak amplitude of G

Water level

Pressure loss coefficient liquidphase

k vi + K J. (»addition to nomi-cables instr v

nal reactor channel)

Units

2m

m2

kg/m2a

m

ex

in

inlet

k + k ,, + k at exit of bundlesp cables ace

k for inlet including downcomer

k for inlet of test section

Lm

M

N

n

P

ApP

PH

(q/A)

(«/!>'Q

Q/V

r

Re

S

t

A ts

T

X

y

Heated lengthmass flow

Mixing coefficient

No. of bit intervals in pseudoran-dom sequenceNo. of cases

Pressure in steam drum

Pressure drop

Perimeter

Heated Perimeter

Surface heat flux

Bundle mean surface heat flux

Nominal power (through A)

Coolant power density (over L)

Radius

Reynold's number

Slip ratio

Time

Sampling time interval

Period

Quality

Transfer function

mWs

bars

bars

m

m

W/cm2

W/cm2

kW

kW/l

m

8

S

8

- D I -

z

a

&

A

A^subV

ea

Subscripts

ace

BO

oorr

e

ex

exp

f

ghorn

in

instr

1

max

sep

sp

sub

xy

T.P., gainT.F., phase

Height coordinate

Void fraction

Deviation (dynamic)

Deviation (static), difference

Perimeter ratio (sp_/P)

Temperature

Inlet subcooling

Frequency

Break frequency

Density

Standard deviation

Variance

Two-phase flow friction multiplier

Acceleration

Burnout

Correlation

Elevation

Exit

Experiment

Friction (, fluid)

Steam

Homogeneous

Inlet

Outlet instruments

Liquid

Maximum

Steam separator

Spacer

Subcooling

From parameter x to parameter y

dBdegreesm

°c°cc/s

c/s

kg/m3

- 62 -

References

1. Nylund O et. al.

Measurements ol hydrodynamic characteristics, instability

thresholds, and burnout limits for 6-rod clusters in

natural and forced circulation,

ASEA and AB Atomenergi Report ERIGG-1, 1967

2. Nylund O et. al.

Hydrodynamic and heat transfer measurements on a full-

scale simulated 36-rod Marviken fuel element with uni-

form heat flux distribution.

ASEA and AB Atcmenergi Report FRIGG-2, 1968

3* Nylund O, Eklund R, Gelius 0

FT-36b. General on the experiments.

FRIGG-PM-14, 1968 (ASEA KAB 68-19)

4* Haukeland S, Eklund R, Åkerhielm F

PT-36b. Experiences from measurements with impedance

void gauge and turbine flow meter, (in Swedish)

ERIGG-PM-21, 1968 (ASEA-paper)

5» Björkman J

RAMSES, a flexible data collecting and recording system

for nuclear measurements.

AB ATOMENERGI SSI-123 and Acta Bneco III, 27-SW-194i 1964

6. Nylund 0, Ikerhielm F

Suggested experimental program for the 36-rod test

section PT-36b. (in Swedish)

AB Atomenergi TFM-RFT-169, 1967

7. Kaiser N E

Heat flux distribution in parallelly connected electrically

heated tubes» (in Danish)

ERIGG-JM-7f 1968 (Hisö PRIGG-Note-R 18)

8. Nylund O, Gelius O, Åkerhielm P

FT-36b. Natural circulation steady state experiments.

ERIGG-PM-20 (ASEA KAB 68-26)

9. Mathisen R P

Natural circulation with boiling,

Nukleonik 11. Bd., Heft 1, pp 16-32, 1968

10. Kjaerheim G, Rolstad E

In-pile hydraulic instability experiments with a

7-rod natural circulation channel.

Paper presented at the Symposium on Two Phase Flow

Dynamics, Eindhoven, September 4th-9th, 1967

11. Akcasu A Z

Mean square instability in boiling reactors*

Nucl. Sci. and Eng., .10, 337-345, 1961-

12. Skaug J A, Eklund R, Nylund O

FT-36b. Results of void measurements*

ERIGG-JM-15, 1968 (ASEA-paper)

13. Nylund O

A gamma-ray density gauge for measuring water-steam

mixtures.

ASEA Research 7, pp. 305-320, 1962

14. Ifylund 0

Measurement of radial void distribution in rod clusters

with the gamma-ray attenuation method, (in Swedish)*

ASEA PM KABR 63-31, 1963

15. Skaug J A

On the experimental accuracy of present designs of '

out of pile bundles in the PRIGG-loop; subchannel flow

vs. inlet flow, mixing.

ERIGG-IW-11, 1968 (Kjeller report RT-62)

16. Maines D, Sandervåg O

Void fractions in rod bundles.

Paper to the European Two-phase Flow Group Meeting,

Oslo, June 18-20, 1968 (Kjeller report RT-70)

17. Maurer G W

A method of predicting steady-state boiling vapor

fractions in reactor coolant channels.

WAPD-BT-19, pp. 59-70, 1960

18 n Gelius 0, Skaug J, Jensrud B

a) FT-36b. Results of pressure drop measurements.

ERIGG-IW-22, 1968 (ASEA-paper)

b) FT-56b. Pressure drop base data.

FRIGG-PM-23, 1968 (ASEA-paper)

19. Hernborg G

Investigation of E- and G-type spacers, (in Swedish)

AB Atomenergi RTL-85O, 1966

20. Hernborg G

Pressure drop measurements on a Marviken boiler channel.

(In Swedish)

AB Atomenergi RTL-880, 1966

21. Gelius 0, Norlander G

TRYCK II. GE-625 program för utvärdering av uppmätta

2-fastryckfall i bränslepatroner, (in Swedish)

FRIGG-IM-33, 1969 (ASEA-paper)

22. Becker K M et. al.

An experimental study of pressure gradients for flow of

boiling water in vertical round ducts.

AE-69, AE-70, AE-85 and AE-86, 1962

Owens V L

Two-phase pressure gradient»

International Developments in Heat Transfer, Pt. II,

ASME, pp. 363-368, 1961

- 6$ -

24. Jones Å B , Dight DG

fydrodynamic stability of a boiling channel.

KAPL-217O, 1961. KAPL-22O8,

25. Mårtinelli R C, Nelson D B

Prediction of pressure drop during forced circulation

boiling of water.

Trans, ASME, JO p. 695, 1948

26. Ikerhieim P, Eklund R, bylund O

PT-36b. Results of dynamic measurements.

FRIGG-PM-31, 1969 (ASEA-paper).

27* Balcomb J D, Demuth H B, and Qyftopoulos E F

A cross-correlation method for measuring the impulse

response of reactor systems.

Nucl. Sci. and Bng., ji. pp. 1^9-166, 1^61

28. Bliselius P-Å et.al.

Experimental dynamic studies in the Ågesta power reactor.

AB Atomenergi RJT-128, R3-365, 1965

29. Bliselius P-Å, Tollander B

KORSKOHAN: A computer program for transfer function

calculation.

AB Atomenergi RFN-199, RFT-132, 1965

30. Bäckman A et. al.

EKORRHARE. A computer program for evaluation of transfer

functions from sampled data by correlation technique or

direct harmonic analysis, (in Swedish).

ASEA KXC R 42003, 1966

31* Jensen A

PT-36b. Result of burnout measurements.

FRIGG-iM-16, 1968 (RISÖ FRIGG-Note R 30)

32. Becker K M

A correlation for burnout predictions in vertical rod

bundles.

AE-276, 1967

33. Becker K M

An Analytical and Experimental Study of Burnout Condi-

tions in Vertical Round Ducts, NufcLeonik, Bd 9 (19^7):6,

P 2i>7

34* Kristoffersen P

Burnout-resultater fra ERIGG-fors^get JT-36b sammenlignet

med henholdsvis svenske og danske beregninger* (in Danish)

FRIGG-PM-9 (1^68) (RIS0 ERIGG NOTE R-15).

35. Bech N, Olsen A

A preliminary description of BOSFLOW, a two-phase hydraulic

computer model»

R D meno N13» 1969. Danish Atomic Energy Commission Research

Establishment, Risff, Denmark

36. Hansson P T, Axelsson E

HYDRO. A digital model for one-dimensional time-dependent two-

phase hydrodynamics*

KPR-492 / RFN-21O, AB Atomenergi, Sweden,

37* Hansson P T

HYDRO. A digital model for one-dimensional time-dependent two-

phase hydrodynomics. Bart 2

RFR-596, AB Atomenergi, Sweden, 196/

33. Bakstad P, Solberg K 0

A Model for the Dynamics of Nuclear Reactors with Boiling

Coolant with a New Approach to the Vapour Generating Process.

Kjeller Report No. KR-121, 1967

Cortzen F V, Olsen A, Abel-Larsen H

Prediction of Burnout in the Marviken out-of-pile Fuel Test-

elements, using the HAMBO Programme and the Becker Burnout

Correlation*

Risö - M900, Ris^, Denmark, 1969

- O,' -

40. Bovring R V

Physical Model, Based on Bubble Detachment and Calcu-

lations of Steam Voidage in the Subcooled Region of a

Heated Channel*

Institutt for Atomenergi, HPR 10, Balden, Norway, 1962

41. Bowring R W

HAMBO, A Computer Programme for the Subchannel Analysis

of the Ifydraulic and Burnout Characteristics of Rod Clu-

sters*

AEEW-Ri?24, 1^7 and AEEW-Ri>82,

Appendix 1. Survey of measurements performed on FT-36b. First test period (November 1967)A1

Loop conditions

lype»f3iro.

F

P

PF

P

P

P

P

P

P

P

F

P

P

P

F

P

P

P

P

kin

v.h.

H

m

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

p

bars

8.78.78.78.78.78.78.78.78.78.78.78.78.78.78.78.78.7

8.720.3

20.3

sub

°C

154

154

154154152

150

149

149

148

146

145144

143

143

142

141

140

139

30

26

Q

kW

0

0

0

0

0

0

c0

0

0

0

0

0

0

0

0

0

0

0

0

(q7DW/om2

0

0

0

0

0

0

0

0

0

0

0

c0

0

0

0

0

0

0

0

W/om2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

kg/m2s

770

1051

1191

2017

2550

715

876

1191

2017

2550

7151051

1429

2017

2522

715

1429

2522

6981036

xex

i0

0

0

c0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Steady state measurements

G-f(Q) Burn-out

Pres-suredrop

404001

404002

404003

404004

404005

404006

404007

404008

404009

404010

404011

404012

404013

404014

404015

404016

404017

404018

404019

404020

Temp,distr.

405001

Voiddistr.

Eynamio measurement

Noise Step Binarypertuibatiot

F * Foroed oiroulationN - Natural circulation1) Experiment interrupted beoause of instability2) Experiment interrupted beoause of burnout

Appendix 1. (Cont'xi) First test period

Loop conditions

>fJiro.

F

F

P

PP

F

F

P

F

F

F

P

P

P

F

P

F

P

PF

km H

m

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

10.1

10.1

10.1

10.1

10.1

10.1

10.1

10.1

10.1

10.1

p

bars

20.3

20.3

20.3

20.3

21.2

24.1

24.1

25.0

25.0

24.6

48.8

48.8

48. b1

50.8

50.3

50.3

50.3

50.3

56.356.8

sub

°C

23

20

21

21

24.0

26

24

24

23

20

5.2

3-7

4.77.0

7.6

6.1

6.1

6.1

1416

Q

kW

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(Q7I)

W/om2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

W/om2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1 - Forced oiroulation* Natural oiroulation) Experiment interrupted because of instability) Experiment interrupted because of burnout

0

kg/m 8

1414

1932

2480

711

1438

1460

2480

2477

24751410

292

292

1104

1524

1524

1373

1520

1006

1007

2576

xex

i0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Steady state measurements

G-f(Q) Burn-out

Pres-suredrop

404021

404022

404023

404024

404025

404026

404027

404028

404029

404030

404031

404032

404033

404034

404035

404036

404037

Temp,distr.

405002

405003

405004

405005

Voiddistr.

Dynamic measuremen

Noise Step Binar;pertu:batio:

Appendix 1. (Cont'd) Pirat test periodA3

&f3iro.

PPPPPPPPPFPPPFFPNNNN

kmv.h.

13.4

13.3

13.3

13.3

H

m

10.1

10.1

10.1

10.1

10.1

10.1

8.0

8.0

7.8

7.8

7.8

7.77.557.55

7.55

7.556.06

5.92.

5.92

5.92

Loop o on ditione

P

bar 8

56.8

57.8

58.8

58.8

58.8

78.6

51.5

51.0

51.5

51.0

51.0

50.9

49.5

49.5

49.5

49.5

50.2

50.0

49.8

50.1

A* .sub

°C

16

1718

18

19

11.7

1.4

1.4

1.4

1.9

1.9

3.1

2.4

2.9

3.1

2.0

1.9

1.9

2.3

2.2

Q

kW

0

0

0

0

0

19952988

2988

2978

3008

2998

4680

4529

4529

4529

4529

1072

1072

1488

1995

(q7T)W/om2

0

0

0

0

0

29.3

43.9

43.9

43.7

44.2

44.0

68.7

66.5

66.5

66.5

66.5

15.7

15.7

21.9

29.3

<*A>maxW/om2

0

0

0

0

0

34.6

51.8

51.8

51.552.2

51.9

81.0

78.5

78.5

78.5

78.5

18.5

18.5

25.8

34.6

0

kg/m2s

25712550

£6201106

1681

1797

1080

1081

1087

502

502

1975

2013

2013

1032

728

840

833

860

862

xex

i0

0

0

0

0

1.1

11.5

11.5

11.4

25.1

25.0

9.2

8.9

8.7

17.7

25.9

4.9

4.9

6.7

9.2

Steady state measurements

O-f(Q)

401001

401002

401003

401004

Burn-out

Pres-suredrop

404038

404039

404040

404041

404042

404043

404044

404045

404046

404047

404048

404049

404050

404051

Temp,distr.

405006

405007

405008

Voiddistr.

413001

413002

413003

413004

Dynamio measurement

Noise

450001

Step Binarypertuzbatior

F * Foroed circulationK - natural oiroulation1) Experiment interrupted because of instability) Experiment interrupted because of burnout

IAppendix 1.

-

firo.

N

N

N

N

N

N

N

N

N

N

VN

N

N

N

N

N

N

K

II

kin

v.h.

13.1

13.0

13.0

12.5

12.1

12.8

12.8

12.8

12.9

13.0

13.0

13.0

13.0

13.0

13.0

13.0

13.0

13.0

13.0

13.0

(Cont *-d) First test period

Loop conditions

H

m

5.92

5.92

5.92

5.92

5.92

5.92

5.92

6.0

5.98

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

P

bars

50.1

50.0

50.0

49.5

49.6

49.649.4

49.7

49.7

49.7

49.7

49.7

49.4

49.4

48.9

49.3

49.3

49.3

49.1

49.0

sub

°C

1.8

1.6

1.6

2.0

2.6

2.3

2.6

2.6

2.6

1.7

1.7

1.7

1.7

1.7

1.7

1.7

1.7

1.7

2.0

2.0

Q

kW

2502

3008

3008

3515

4022

4529

4529

5035

5541

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

(UK)W/om2

36.7

44.2

44.2

51.6

59.1

66.5

66.5

75.9

81.4

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

w/ora2

43.3

52.2

52.2

60.9

69.7

78.5

78.5

89.6

96.1

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

• Forced oiroulation« Natural oiroulation) Experiment interrupted beoause of instability) Sxperiaent interrupted because of burnout

0

855840

840

792

771

747747

725697828

828

831

824

824

821

821

821

821

813

8,6

xex

i11.9

13.0

13.0

18.5

21.7

25.4

25.4

28.9

i3.1

15.0

15.0

4.9

5.0

5.0

5.1

5.1

5.1

5.1

5.2

5.1

Steady state measurements

G-f(Q)

401005

401006

401007

401008

401009

401010

401011

401 012

Burn-out

Pres-suredrop

404053

Temp,distr.

Voiddistr.

A4

Dynamic measurement

Noise

450002

450003

450004

450005

450006

450007

450008

Step Binaryper t inbatior

462001

462002

462003

462004

462005

462006

462007

462008

462009

462010

462011

1. (Cont'd) First test period A5

ofoiro.

V

N

N

NN

W

VN

NN

N

N

N

N

N

N

N

N

N

N

ki»

v,h.

13.0

13.0

13.0

13.0

13-0

13.0

13.0

13.0

13.0

13.0

20.0

19.8

19.8

7.6

7.2

7.2

8.0

8.0

12.8

11.0

H

m

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

6.0

5.92

5.92

Loop conditions

P

bars

49.0

49.349.0

49.2

49.3

49.3

49.3

49.3

49.3

49.3

49.3

49.349.3

49.3

49.1

49.1

49.1

49.1

49.6

49.6

Ad .sub°C2.3

2.4

2.0

2.0

2.0

2.0

2.0

1.7

1.5

1.5

1.7

1.9

1.7

1.7

1.51.7

1.51.2

5.14.9

Q

kW

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

3008

982

1492

(q7DW/om

44.2

44.2

44.2

44.244.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

44.2

14.4

21.9

<*/A>max

W/om2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

17.0

25.8

G

kg/m 8

803

824

821

821

825

828

828

820

817

817

763

770

758881

915

915

865865

764830

xex

15.2

14.8

15.0

15.0

14.9

14.9

14.9

15.1

15.2

15.2

16.2

16.1

16.4

13.9

13.6

13.5

14.3

14.5

3.96.2

Steady state measurements

G-f(Q)

401013

401014

Burn-out

Pres-suredrop

404054

Temp,distr.

Voiddistr.

fynamio measureme

Noise

450009

Step Binapertbat i

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

4620

F - Forced circulationN « Natural circulation1) Experiment interrupted because of instability2) Experiment interrupted because of burnout

Appendix 1. (Cont'd) First test periodA6

typeofoiro.

K

N

N

N

N

N

N

N

N

N

N

N

*

K

H

H

H

K

N

k.xn

v.h.

12.8

13.0

12.7

12.7

12.7

12.6

12.7

12.1

4.6

4.54.6

4.7

4.7

4.4

4.4

4.4

4.4

12.9

12.9

12.9

H

m

5.92

5.92

5.92

5.92

5.92

5.88

5.88

5.74

5.88

5.88

5.89

5-90

5.90

5.90

5*90

5*90

5-90

5.88

5.88

5.88

Loop conditions

P

bars

49.6

50.0

49.6

49.6

50.0

49.7

49.7

49.9

50.0

50.0

50.0

50.0

50.0

49.8

49.8

49.8

49.8

49.9

49.9

49.9

A* ,sub

°C

5.2

5.0

5-2

5.2

5.2

5.6

5.0

4-5

3.4

3.3

3.3

3.1

3.2

2.9

2.9

2.9

2.9

3.2

3.2

3.2

Q

kW

1995

2502

3008

3008

3516

4022

4529

5035

982

1489

1995

3008

4022

3009

3009

3009

3009

3009

3009

3009

(Q7I)

W/cm2

29.3

36.7

44.2

44.2

51.6

59.0

66.5

73.9

14»4

21.8

29.3

44.2

59.1

44.2

44.2

44.2

44.2

44.2

44.2

44.2

W/om2

34.6

43.3

52.2

52.2

60.9

69.6

78.5

87.2

17.0

25.7

34.6

52.2

69.7

52.2

52.2

52.2

52.2

52.2

52.2

52.2

F * Foroed circulationF - Natural circulation1) Experiment interrupted beoauee of instability2) Experiment interrupted because of burnout

0

kg/m 8

853

853

825

825

800

775

741

711905

966

967

911

841

904

904

904

904

813

813

813

xex

i8.4

11.0

14*0

14.0

17.2

20.4

>4.6

>8.8

3.6

5.6

7.8

3.2

20.0

3.3

3.3

3.3

3.3

4.8

4.8

4.8

Steady state measurements

G-f(Q)

401015

401016

401017

401018

401019

401020

401021

401022

401023

401024

401025

401026

401027

401028

Burn-out

Pres-suredrop

404055

Temp,distr.

Voiddistr.

Dynamic measuveme

Noise

450010

450011

450012

450013

450014

450015

Step Binapertbat i

46202

46202

46202

46202

46202

46202

4620]

Ippendix 1. (Cont*d) First test period A7

TJjrpeofo i r o .

9HH

NN

K

N

K

H

N

N

N

N

N

N

N

N

N

N

kin

v.h.

12.9

13.0

13.0

13.0

13.0

13.0

13-0

12.4

12.4

12.4

13.2

13.2

13.2

12.6

12.6

12.6

12.9

12.9

12.8

H

01

5.885.885.885.885.885.885.885.885.885.88

5.895.895.895.885.885.885.886.10

6.10

Loop conditions

P

bars

»9.9»9.8»9.8»9.8»9.8»9.8»9.849.849.849.849.850.049.849.849.849.849.849.849.8

AS ,sub°C

3.2

5.95.95.95.95.95.99.1

9.1

9.1

14.614.6

14.6

14.9

14.9

14.923.422.9

22.9

Q

kW

30093008

3008

3008

3008

3008

30083008

3008

3008

3008

3008

3008

3008

3008

3008

3008

35154022

(q?A)

W/cm2

44.2

44.2

44.2

44.2

44.244.244.244.244.244.244.244.2

44.2

44.2

44.2

44.244.251.6

59.1

<*A>maxW/cra2

52.252.252.252.252.252.252.252.2

52.2

52.2

52.2

52.2

52.2

52.2

52.2

52,252.2

60.9

69.7

G

kg/m s

813

813

813

813

813

813

813821

821

821

825

825

825

807

807

807809

809

797

xex

i14.814.0

14.0

14.0

14.0

14*0

14.0

12.9

12.9

12.911.2

11.2

11.2

11.5.

11.5

11.58.9

11,6

14.7

Steady state measurements

G-f(Q)

401029

401030

401031

401032

401033

401034

401035

Burn-out

Pres-suredrop

Temp,distr.

405010

405011

Voiddistr .

Dynamic meaeuren

Noise Step Binperbat

462

462

462

462

462462462462

462

462

462462

462

462

462

462

F • Poroed oiroulationN « Natural circulation1) Experiment interrupted beoause of instability?) Experiment interrupted beoause of burnout

Appendix 1, (Cont'd) First test periodAS

Loop conditions Steady state measurements Itynamic measureme

TypeofCJTO. v.h.

H

m

P

bars

Aftsub

C

Q

kW

(q?A)

W/om2

(q/A)max

W/icm kg/m sex

G-f(Q) Burn-out

Pres-suredrop

Temp,distr.

Voiddistr.

Noise Step Bineperlbat i

N

N

N

12.9

12.9

12.9

6.10

6.10

6.10

49.8

49.6

>0.0

.

23.4

22.9

22.9

4529

4529

4529

66.5

66.5

66.5

78.5

78.5

78.5

783

783

783

7.8

7.9

7.9

401036 462C

462C

462C

F * Foroed circulationN • natural circulation1) Experiment interrupted beoause of instability2) Experiment interrupted beoause of burnout

ippendix 1. (Cont'd) Second test period (December 1967)

Loop conditions

•typeofoiro.

P

P

P

P

P

P

PNN

N

N

NN

N

N

N

N

N

N

N

k i n

v . h .

13.413.9

13.9

14.4

14*213.5

13.9

13»9

13.9

13.9

13.9

13.9

13.9

H

m

>10

>10

7.927.92

7.92

7.85

7.856.905.98

5.92

5.925.925.92

5.91

5.915.915.91

5.91

5.915.91

P

bars

22.0

22.0

50.2

50.350.350.0

49.8

49.349.349.8

49.850.149.8

49.349.349.349.349.649.8

49.4

sun

°C

17.0

17.0

8.1

9.48.0

9-4

7.94.04.0

4.0

4.0

3.94.2

4.0

3.03.0

3.53.0

3.1

3.0

Q

kW

0

0

55685600

61776642

6902

14852990

3495400345135024

4003

45134513

4513

451345134513

<*7I)W/om2

0

0

81.882.1

90.7

97.5

101.321*8

43.9

51.3

58.966.473.8

59.2

66.466.466.4

66.466.4

66.4

W/om2

0

0

96.597.0

108.0

115.0

119.525.751.9

60*5

69.578.487.0

78.478.478.4

78.4

78.478.478.4

G

kg/m s

1210770

475467598712

796830

822

788

752730

704760

738742

742

744741

737

x ex

*

0

0

47.6

48.3

41.737.0

34.6

6.4

14.3

17.7

21.525.229.2

21.2

25.125.0

24.8

25.0

25.0

25.2

Steady state measurements

G-f(Q)

401101

401102

401103

401104

401105401106

401107

Burn-out

403101

403102

403103

403104403105

Pres-suredrop

404101

404102

Temp,distr.

405101

405102

Voiddistr.

413101

413102

413103

fynamic meaeurera

Noise Step Binperbat

462

462

462

462

462

462

P - Forced circulationN - Natural circulation1) Experiment interrupted because2) Experiment interrupted because

of instabilityof burnout

Appendix 1•

fmmmmmmmmmmmmmmam(Cont'd) Second test period

HBHHH

Loop conditions

•typeofo i r e .

NN

N

NN

NK

NNHH

KNHNN»

HH

k.in

v.h.

13.913.913.913.913.913.913.9

13.9

13.9

13.913.9

13.9

13.9

13.913.913.913.913.913.9

13.9

H

m

5.915.915-905.91

5.915.905.915.915.915.915.915.915.915.915.915.915.915.915.915.91

P

bars

49.349.249.849.849.849.649.649.649.649.449.649.849.749.649.649.649.649.649.649.6

sub

°C

3.0

3.0

3.0

2.8

2.8

6.36.4

6.56.8

6.46.3

10.410.8

10.8

10.8

10.8

10.510.8

10.8

14.5

Q

kW

4513

45134513451345134513451345134513

4513

4513

45134513451345134513451345134513

4513

(o7I)W/cm2

66.466.466.466.466.466.466.466.466.466.466.466.466.466.466.466.466.466.466.466.4

C*AU,W/cm2

78.478.478.478.478.478.478.478.478.478.478.478.478.478.478.478.478.478.478.478.4

F • Forced oiroulationV » natural oiroulation1) Experiment interrupted because of instability2) Experiment interrupted because of burnout

G

kg/m s

736736760730730725716730728

735720

705731719786786786786786

750

x ex

25.2

25.2

24.4

25.525.524.6

24.924.424.424.2

24.8

24.2

23.1

23.521.2

21.2

21.321.2

21.2

21.3

H H H H M B H H M M •HiHIlBHH

Steady s tate measurements

O-f(Q) Burn-out

Pres-suredrop

Temp,distr .

Voiddistr.

413104

wmmmm

A10

Dynamic measuremei

Noise Step Bina]pertibati<

46211462114621146214621462146214621462146214621462146214621

462146214621462146214621

Appendix 1. (Cont*d) Second test period A11

trp«ofwire*

9

H

9

9

9

9

9u9

9

9

9

HH9

9

9

9

9

9

kin

v.h.

13.9

13.9

13.919.6

19.6

19.6

19.6

19.6

8.58.58.58.58.54.74.74-74.713.6

13.6

13.6

H

m

5.91

5.91

5.915.915.915.915.915.915.915.91

5.91

5.91

5.915.915.915.91

5.91

5.915.91

5.91

Loop conditions

P

bars

49.6

49.6

49.649.649.649.649.649.649.6

49.6

49.6

49.6

49.649.649.649.649.649.649.649.6

sub

°C

14.2

14*2

14.2

3.0

3.0

3.0

2.8

2.4

3.0

3.5

3.53.53.52.5

2.8

2.8

2.8

2.8

2.5

2.6

Q

kW

4513

4513

4513

4513

4513

4513

451345134513

4513

4513

4513

4513

4513

4513

4513

4513

4513

4513

4513

(OT)W/cm2

66.4

66.4

66.4

66.466.466.466.466.466.466.4

66.4

66.4

66.466.466.466.4

66.4

66.466.4

66.4

w/om2

78.478.478.478.478.478.478.478.478.4

78.4

78.478.478.478.478.478.478.478.478.478.4

G

kg/m s

750

756752700

677677687687775769

769

769

769804

770

756756

734Y30

730

xex

*

21.4

21.4

21.4

26.6

27.527.527.2

27.3

23.9

24.O

24.O

24.O

24.O

23.2

24.1

24.6

24.6

25.425.6

25.6

Steady state measurements

G-f(Q)

401108

401109

401110

401111

Burn-out

Pres-suredrop

Temp,distr.

•

Voiddistr.

Dynamic measuremei

Noise Step Bina:pertibati<

4621

4621

4621

4621

4621

4621

4621

4621

4621

4621

4621

4621

4621

4621

4621

4621

F *• Forced circulationN - Natural oiroulation1) Experiment interrupted beoause of instability

Experiment interrupted beoause of burnout

Appendix 1. (Cont*d) Second test period A12

Loop conditions

Typeofoiro»

N

N

N

N

NN

N

H

N

N

H

N

HN

9

N

9

H

H

H

k.in

v.h.

13.613.8

13.8

13.8

13.8

14*0

13.914*1

13.814*2

14*1

14.114*0

13.514.O

14.3

14.314.3

13.713.2

H

ra

5.915.92

5.925.92

5.92

5.855.855.855.855.855.855.855.875.8É5.8é

5.865.8é5.8é5.&5.9C

P

bars

49.649.649.649.649.6

49.2

49.6

50.0

50.0

49.8

49.849.8

49.8

50.0

49.8

49.649.649.649.649.8

sub

°C

2.6

2.8

2.8

2.8

2.8

3.0

3.33.0

2.93.0

3.0

3.0

3.33.0

3.13.0

3.0

2.2

6.8

7.5

Q

kW

4513

5024

5024

5024

5024

9781480

1981

24852990

34954003

4513

502455386008

6OO8

6146

978

148O

(q7X)W/cm2

66.473.873.873.8

73.8

14.4

21.7

29.1

36.543.9

51.3

58.966.473.881.2

87.1

87.1

90.1

14.4

21.7

W/om2

78.487.0

87.0

87.0

87.0

17.0

25.6

34.3

43.1

51.9

60.5

69*5

78.487.O95.8

104.0

104.0

106.517.025.6

F * Forced circulationI • Hatural circulation1) Experiment interrupted because of instabilityfc)* Experiment interrupt eel because of burnout

G

kg/ra s

730

692

682

682682

756

810

823815

786

767

739

713690

656649649649698

793

xex

25.6

30.1

30.6

30.6

30.6

4.6

6.8

9.412.1

15.3

18.522.2

26.030.2

35.138.638.6

39.7

3.9

5.7

Steady state measurements

G-f(Q)

401112

401113

401114

401115401116

401117401118a

401118b

401119401120

401121

401122

40112 3 e

401124401125

Burn-out

Pres-suredrop

Temp,dis t r .

Voiddis t r .

Dynamic measuremei

Noise

450101

450102

450103

450104

450105450106

450107450108

450109

450110

450111

Step Bina]pertibati<

4621

4621

4621

4621

Appendix 1* (Cont'd) Second test period AI:

Iferpeofoiro.• *

N

K

N

N

N

N

N

N

NN

N

N

N

N

N

N

N

NN

k i nv .h .

13.6-13.8

13.414.0

13.713.413.2

13.112.913.2

13.413.813.6

13.713.613.6

13.913.413.314.0

H

m

5.905.905.90

5.895*905.905.905.90

5.90

5.895.895.90

5.90

5.90

5.915.905.905.90

5.90

5.89

Loop conditions

P

bare

50.150.050.0

49.949.850.049.8

49.849.849.8

49.349.350.049.8

49.849.849.849.849.8

50.1

sub°C

7.0

6.36.37.0

6.36.8

6.36.36.36.2

15.0

15.5

15.515.415.015.2

15.415.2

14.515.0

Q

kW

1981

24852990

34954003451350245538

59506260

97814801981

24852990

34954003451350245538

(q7I)W/om2

29.1

36.543.951.358.966.473.881.2

87.492.0

14*421.7

29.1

36.5

43.951.358.966.473.88 1 . 2

W/om2

34.343.151.960.569.578.487.O95.8

103.0108.5

17.0

25.6

34.343.151.960.569.578.487.O95.8

G

kg/m s

827824809782

764740

719

695679667

576682

760798

803790772752739712

xex

8.111.0

13.917.0

20.424.0

27.932.1

35.538.22.84.6

6.58.7

11.414.3

17.521.1

24.6

28.7

Steady state measurements

O-f(Q)

401126

401127401128

401129401130

401131401132

401133

401134,4011 y?

401136

401137401138

401139401140

401141

401142

401143

401144

401145

Burn-out

Pres-suredrop

Temp,distr .

Voiddistr .

Dynamic oeaeurem

Noise

450112

450113

450114450115450116

450117450118

450119

450120

450121450122

450123

450124

45.0125

St*f Binperbat

F - Foroed oiroulationH • Natural oiroulation1) Experiment interrupted beoause of instability2) Experiment interrupted beoause of burnout

Appendix 1. (Cont'd) seoond test period

F - Foroed circulationN « Katural oirculation1) Experiment interrupted because of2) Experiment interrupted because of

typeofc i r e .

N

N

N

N

N

N

K

N

N

"S

N

N

N

N

N

N

K

N

N

N

k.in

v.h.

13.413.314.8

14.2

14*0

14-114.8

13.7

14.3

14.1

14.513.2

14.0

14*6

13.413.94*8

4.74.9

5.1

H

m

5.905.905.905.90

5.905.905.905.905.905.905.905.905.905.905.905.905.92

5.905-905.90

Loop conditions

P

bars

49.8

50.0

50.1

50.3

50.0

50.0

50.1

50.3

50.349.8

50.350.2

50.350.350.1

50.349.8

50.350.350.1

©nia

°c

14.0

14.8

14.310.6

10.5

10.310.0

9.3

9.325.6

24.2

24.8

24.5

24.524.522.2

2.8

3.0

3.3

3.3

Q

kW

6053

57435950

4013

4513

50245538

60536208

4003

4513

50245538

6053

5743

6053978

1480

1981

2485

(q7S)W/om

89*0

84.1

87.359.0

66.473.881.2

89.0

91.1

58.9

66.473.8

81.2

89.0

84.189.0

14.4

21.7

29.1

36.5

0

w/om

105.0

99.5103.0

69.578.487.O95.8

105.0

107.569.578.487.O95.8

105.0

98.5105.0

17.0

25.6

34.343.1

0

kg/» •

712

712

712

756740

714705

705705805

79577574^

745750

725916

974964942

x ex

32.130.0

31.4

19.522.9

26.9

30.5

33.934.813.6

17.120.3

24.527.525.429.1

3.75.67.8

10.3

Steady s ta te measurements

O-f(Q)

4011461

401147401148

401149401150

401151401152

401153401154^

401155401156

401157401158

4011594011604011611401162

401163401164401165

Burn-out

Pres-suredrop

Temp.distr.

Voiddistr.

Dynamic measurem

Noise

45012<45012'45012145012<

Step

i

45013()

45013^

450132

450133

45013^

45013!

45013<

45013:

4501ll

45O13S

45O14C

450141

450142

450143

45014^

Bin-perbat

ii

instability

burnout

Appendix 1. (Cont'd) second test period

Loop oonditions

typeofo i r o .

NNNN

N

N

N

N

N

N

N

N

N

N j

N ;

N

N

N

Ni ITi * !

kinv.h.

5.45.45.16.1

5.05.55.14.44*44.4

22.021.0

21.521.42L5

21.521.0

21.521.521.2

H

m

5.905.905.905.885.905.905-895-895.895.895.905.905.915.905.905.905.90

5.955.925.90

P

bars

50.150.149.649.6

49.549.849.649.649.649.649.449.649.849.849.849.649.649.650.049.8

°C

3.03.02.52.82.83.03.03.03.03.02.83.03.02.82.82.82.82.82.62.8

Q

kW

2990

34954003451350245538

5898

579557955795

97814801981

24852990

34954003

451350245538

(q7I)W/om^

43.951.358.966.473.881.286.6

85.185.185.114.421.729.136.543.951.358.966.473.881.2

W/om2

51.960.569.578.487.095.8

102.0

100.5100.5100.5

17.025.634.343.151.960.569.578.487.095.8

0

907874841800

767730700

709709

709

705762

767762

747728

720

693667647

x ex

*

13.216.2

19.523.227.1

31.535.033.933.933.95.17.4

10.1

13.1< 6 . 2

19.6

22.9

26.931.435.1

Steady state measurements

O-f(Q)

401166

401167401168

401169401170

401171401172^

401173

401174

401175401176

401177401178

401179

401180

401181401182

401183

Burn-out

Pres-suredrop

Temp,distr.

Voiddistr.

Eynamio measur

Noise

450145450146

450147450148

450149450150

450151450152

450153450154

450155

450156

450157

450158

450159450160450161

Step BPbi

F - Forced circulationN - Natural circulation1) Experiment interrupted beoause of2) Experiment interrupted beoause of

instabilityburnout

a a a g a » ^ •.,.^,to.w,....i.llM||ll||

Appendix 1. (Cont'd) second tost period

F * Foroed oiroulation

1) Experiment interrupted beoause of2) Experiment interrupted beoause of

typeofoiro*

KN

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

H

v.h.

21.3

21.321.3125128

129

135135135139135126126

296

273253252

256256

255

H

n

5.905.905.90

5.895.89

5.895.895.905.905.90

5.89

5.895.895.905.905.905.90

5.905.9C5.9C

Loop oonditions

P

bars

49.849.849.8

49.649.6

49.649.649.849.849.849.8

49.849.8

50.349.849.849.8

49.850.049.8

* \3L w9

°c2.82.82.8

3.33.0

3.0

2.52.83.0

3.33.03.0

2.53.03.0

2.9

3.13.13.13.0

kW

6115

60536053

9781480

1981

24852990

349540034513

50245281

978148O1981

24852990

34954003

(o7X)W/om

89.989.089.0

14.421.729.1

36.543.951.358.966.473.8

77.514.421.729.1

36.543.951.358.9

(q/A)

W/om

106.Ö105.0105.0

17.025.6

34.343.151.96O.5

69.578.487.0

91.517.025.6

34.343.151.96O.5

69.5

0

kg/m s

632632632418

456456

459456456450

455455455306

345367372372372378

X

i>40.440.040.0

9.0

12.917.6

22.327.1

.31.837.0

41.446.248.8

12.8

17.422.227.6

33.439.2

44.3

Steady state measurements

O-f(Q)

401184401185

401186

401187401188

401189401190401191401192

401193401194

401195^401196

401197401198401199401200401201

Burn-out

401202

Pres-suredrop

Temp.distr .

Voiddistr .

Dynamio measuvem

Noise

450162

450163

450164

450165450166450167450168450169450170

Step Binperbat

I

Iinstability

burnout

Appendix 1. (Cont'd) Second test period

ofoirc.

H

N

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

k

v.h.

255255

H

m

5.905.90

5.915.915.90

5.915-905.905.905-905.905-905.905.905.90

5.99

5.945.91

5.90

5.90

Loop conditions

P

bars

49.850.050.048.2

48.449.850.2

50.2

50.2

50.3

50.3

50.3

50.349.8

49.8

50.0

50.0

50.350.0

49.6

Ad

°c

3.03.0

0.5

0.5

0.5

0.52.8

2.8

2.8

24.5

24.5

24.5

24.5

0.5

0.5

0.5

0.5

3.53.42.8

Q

kW

45134666

0

0

0

0

2990

2990

2990

2990

2990

2990

2990

0

0

0

0

1480

1480

2995

W/cm2

66.468.5

0

0

0

G

43.9

43.9

43.9

43.943.9

43.9

43.90

0

0

0

21.7

21.7

44.0

W/om2

78.480.7

0

0

0

0

51.9

51.9

51.9

51.9

51.9

51.9

51.90

0

0

0

25.6

25.6

52.0

G

kg/m 8

378381

500

698

1070

1580

813

813

813808

808

808

808

511706

1018

146O

502

498

487

x ex

50.0

51.40

0

0

0

14.9

14.9

14.9

8.58.58.58.5

0

0

0

0

11.511.725.4

Steady s ta te measurements

G-f(Q)

401203401204

Burn-out

Pres-suredrop

404103

404104

404105

404106

404107404108

404109404110

404111

404112

Temp,distr.

Voiddistr.

413105413106

—fynamie measure™Noise

450171

450172

Step B i lPefl

I111114 6 |4 6 |4 6 |461

4 6 |

1111111F « Forced circulationN - Natural circulation1) "Experiment interrupted because of2) Experiment interrupted because of

instabilityburnout

Appendix 1. (Cont«d) Second teet period A18

F * Foroed circulationmm Katural circulation1) Experiment interrupted beoause of instability) Experiment interrupted because of burnout

^rpeofcirc.

F

FFF

FFFFFFFFFF

| FF

* FF

1 F\*

*<in

v.h»

13.5

H

m

5-905.905.905.905.905.895.905.915.915.915.925.905.905.905.905.905-905.905.905.92

Loop conditions

P

bars

49.650.0

50.0

49.849.849.449.849.850.0

49.549.850.1

69.269.269.369.269.269*269.269.2

sub

°C

3.03.3

3.33.0

2.515.025.8

25.725.925.8

30.42.92,83.33.03.03.3

16.015.33.3

Q

kW

1480

2990

45134513

6053451345134513

60532990

2990

45131500

2990

2990

4513

451345134513978

(o7I)W/cm2

21.7

43-966.466.489.066.466.466.4

89.043.943.966.422.0

43.943.966.466.466.466.414.4

W/cm2

25.6

51.978.478.4

105.0

78.478.478.4

105.5

5K951.978.426.0

51.9

51.9

78.478.478.478.417.0

G

kg/m s

1000

995992

2010

1972

9941020

2045

20451020

520

736

500

4951050

987

747

1967950701

Xex

5.411.8

18.48.7

12.314.911.2

1.8

5.04.9

15.6

25.312.9

26.9

12.2

20.1

26.95.1

16.7

5.3

Steady state measurements

G-f(Q)

401205

Burn-out

Pres-suredrop

404113

404114

404115404116

404117

404118

404119

404120

404121

404122

404123

404124

404125404126

404127

404128

404129

404130

404131

Temp,distr.

405103

405104

405105

405106

405107405108

405109

405110

405111

405112

405113

405114

405115405116

405117

405118

Voiddistr.

H31O7413108

413109

413110

413111

413112

413113

413114

413115

413116

413117

413118

413119

413120

413121

413122

413123

413124

413125

Ijynamic measureme

Noise Step Binapertbat i

I

Appendix 1. (Cont'd) Seoond test periodA19

Loop conditions

ofoiro.

9

H

9

9

9

9

9

9

9

9

9

9

9

9

9

9

9

9

9

9

kmv.h.

13.6

13.7

13.4

13.7

13.5

13.6

13.8

13.8

13.7

13.7

13*6

13.513.4

13.6

13.4

13.5

4.54*6

4.74.7

H

n

5.92

5.90

5.925.905.905.905.90

5-90

5-90

5.90

5.90

5 »905*905.905.905.88

5.90

5.90

5.91

5.91

P

bars

69.4

69.4

69.2

69.569.8

69.769.869.8

69.769.2

69.2

69.269.2

69.2

69.770.0

69.2

69.769.669.2

°C

2.9

2.9

2.9

2.53.0

2.5

3.0

2.5

2.9

2.1

15.2

14.915.0

15.2

15.3

14.0

2.8

2*7

2.8

2.5

Q

k»

1480

1981

24852990

34954003

45135024

553858782990

4003

4513

5024

5538

6415

1480

1981

2990

3495

W/om2

21.7

29.1

36.543.951.3

58.966.473.881.2

86.4

43.958.966.473.881.2

94.2

21.7

29.1

43.951.3

W/om2

25.6

34.343.1

51.9

60.5

69.578.487.O95.802.0

51.9

69.578.487.095.811.0

25.6

34.3

51.9

60.5

G

kg/m2s

786

811

830

817

810

796778763747740

811

816

806

790

762

749915

946930

910

X

7.710.3

12.9

16.1

19.0

22.5

25.9

29.7

33.4

36.1

11.8

17.6

20.7

24.2

27.6

35.c6.58.c

13.9

16.9

Steady state measurements

O-f(Q)

401206

401207

401208

401209a

401209b

401210

401211

401212

401213

401214^

401215

401216

401217

401218

401219

40122CP

401221

401222

401223

401224

Burn-out

Pres-suredrop

Temp,distr.

Voiddistr.

Dynamic measurenu

Noise

450173

450174450175450176

450177450178450179

450180

450181

450182

450183

450184

450185450186

Step Biruper'bat:

F « Foroed circulationH - Natural circulation1) Experiment interrupted because of instability

Experiment interrupt ed because of burnout

Appendix 1. (Cont'd) Second test period

F - Forced oiroulation¥ - natural oiroulation1) Experiment interrupted because of2) Experiment interrupted because of

•typeofo i ro .

N

K

N

K

N

N

N

N

N

H

N

H

H

N

H

N

H

H

V

k i n

v . h .

4-74.84.8

4.84.8

4.54-44.64.64.6

4.54*8

13.3

13*413.413.413.413.213.213.3

H

m

5.90

5.90

5.915.915.915.915.90

5.915.905.90

5.905.905.90

5.905.905*905.905.905.905.90

Loop conditions

P

bars

69.569.970.0

69.769.47Q.070.2

69.969.969.7

69.769.829.8

29.929-929.8

29.929.929.929.9

O Uw

°c2.8

3.03.03.03.0

15.215.215.015.014.8

14.514.13.13.03.82.82.82.82.82.8

Q

kW

4003

451350245538

61154003451350245538

5847

60536415

978

14801981

24852990

34953922

4003

(*7I), 0

W/cm

58.9

66.473.881.2

89.958.966.4

7^.8

81.2

85.8

89.0

94.114.4

21.729.1

36.543.9

51.3

57.558.9

(*/A>maxHlCfcJfc

O

W/om

69.578.487.0

95.8106.0

69.578.487.0

95.8

101.3

105.0111.0

17.025.6

34.3

43.151.9

60.567.9

69.5

G

kg/m s

890860838

819808

929915887860850

84582k

837

874857816

772

729673676

x ex

19.923.426.8

30.434.114.117*621.1

. 24.726.628.2

31.:3.*

5.*8 . C

11.1

14J18.q22. d

22 . Å

Steady s ta te measurements

O-f(Q)

401225401226

401227401228

4012294

401230401231401232

401233401234

40123540123$

401237401238

401239401240401241401242

401243401244

Burn-out

Pres-suredrop

Temp.distr.

Voiddistr .

Dynamic measuremc

Noise

450187

450186

45018545O19C

450191450192450193450194

450195450196

450197

Step

¥'i

45019645019945O2O0

450201

450202

450203

450204

Bineperlbatj

instabilityburnout

Appendix 1. (Cont'd) Second test period A21

ofcirc.

N

N

N

II

N

N

N

N

N

NN

N

N

N

K

NN

N

N

N

kl»

v.h.

13.4

13.4

13.2

13.413.0

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

13.3

H

m

5.90

5.90

5.90

5.90

5.90

5.90

5.90

5-90

5.90

5.90

5.90

5.90

5.90

5.90

5.90

5.90

5.90

5.90

5.90

5.90

Loop conditions

P

bars

29.1

30.0

29.8

29.930.0

30.0

30.0

30.0

30.0

30.0

30.0

30.0

30.2

30.2

30.2

30.2

30.2

30.2

30.2

30.2

sub

°C

3.0

3.0

3.0

3.0

3.0

3.0

2.8

3.0

3*0

3.0

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.9

Q

kW

4288

4288

2990

40031981

2990

2990

2990

2990

2990

2990

2990

2990

2990

2990

2990

2990

2990

2990

2990

(q7DW/om2

63.0

63.0

43.9

58.9

29.1

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

43.9

W/om2

74.4

74.4

51.9

69.5

34.3

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

51.9

G

kg/m 8

610

610

769

674852

770

757

766

766

766

726

726

771

771

771762

762

762

760

760

xex

26.5

26.6

14.4

22.4

8.3

14.4

14.7

14.5

. 14.5

14.5

15.3

15.3

14.4

14.4

14.4

14.6

14.6

14.6

14.6

14.6

Steady state measurements

G-f(Q)

4012451^

401246

401247

401248

401249

401250

Burn-out

Pres-suredrop

404132

Temp,distr.

405119

Voiddistr.

413126

Dynamic measuremen

Noise

450205

450206

Step Binarpertubatio

4621!

462V

4621!

4621'

4621;

4621

4621

4621

4621

4621

4621

4621

4611

4611

F • Forced circulationN » Natural circulation1) Experiment interrupted because of instability

Experiment interrupted because of burnout

Appendix 1. (Contfd) Second test periodA22

F - Forced circulationN » Katural oiroulation1) Experiment interrupted beoause of instability2l Experiment interrupted beoause of burnout

Typeofc i re.

N

N

N

N

N

N

N

K

K

N

N

N•a

H

N

N

j

ir

k.i n

v.h.

13.3

13.3

13.3

13.3

4.3

4.1

4.6

4.8

4.8

4.8

4.6

4*6

4.5

4.5

4.6

4*6

4.6

4*6

4.6

4.6

H

m

5.90

5.87

5.875.87

5.90

5.90

5.90

5-90

5.88

5.88

5.88

5.88

5.88

5.88

5-90

5.90

5*90

5.90

5.90

5.90

Loop conditions

P

bars

30.2

30.1

30.2

30.2

29.9

30.1

30.1

30.1

30.0

30.0

30.0

30.0

29.8

29.8

29.8

29.8

29*8

30.0

30.Ö

30.0

o uu

°c

2.9

2.8

2.8

2.8

3.0

3.1

3.0

3.0

3.0

3.0

3.1

3.1

3.0

3.0

3.0

2.8

2.8

2.8

2.8

2.8

Q

kW

2990

2990

2990

2990

978

1480

1981

1981

2485

2485

2990

2990

3495

3293

3293

3394

3394

3293

3293

3293

(q7I)W/om

43.9

43.9

43.9

43.9

14.4

21.7

29.1

?3.1

36.5

36.5

43.9

43.9

51.3

48.4

48.4

49.8

49.8

48.4

48.4

48.4

(*/A>maxIIICUL0

W/om

51.9

51.9

51.9

51.9

17.0

25.6

34.3

34.3

43.1

43.1

51.9

51.9

60.5

57.0

57.0

58.8

58.8

57.0

57.0

57.0

G2

kg/m s

760

778

740

740

986

1012

954

954

892

892

837

837

775

799

799

782

782

775798

765

xex

14.6

14.3

15.1

15.1

3.1

4.9

7.3

7.3

10.1

10.1

13.1

13.1

16.a

15.3

15.3

16.2

16.2

15.9

15.4

16.1

Steady state measurements

O-f(Q)

401251

401252

401253

401254.

401255

401256J

401257

401258

Burn-out

Pres-suredrop

Temp.distr.

Voiddistr

Dynamic measuremer

Noise

450207

450208

450209

450210

450211

450212

450213

450214

450215

450216

450217

450218

Step Binaiper 11batic

461K

461K

461 K

461 K

4611C

4611 c

4611 c

Appendix 1. (Cont'd) Second test periodA23

Typeofc ire.

NRN

NNNN

NNNN

N

NNN

F

F

J

F

F

in

v.h.

4.64*64.64.64.64.64.64.64*64.6

4*6

4*6

4*6

4.6

4.6

H

m

5.905.905.90

5.905*905.905.905.905.905.905.90

5.90

5.90

5.90

5.90

7.857.657.66

6.50

6.50

Loop conditions

P

bars

30.0

30.0

30.0

30.0

30.0

30.0

30.0

30.0

30.0

30.0

30.0

30.1

30.1

30.2

30.2

29.8

3Ö.3

69.769.2

69.0

Ad .sub°C2.6

2.6

2.6

2.6

2.6

2.6

2.6

2.6

2.6

2.6

2.3

2.52.8

2.7

2.7

3.0

2.8

3.8

3.0

2.8

Q

kW

329332933293

3293

3298

3298

3394

33943381

33643496

3496

3331

3321

3321

1480

2990

978

1981

2990

W/em

48.448.448.448.448.548.54.9.9

49.949.6

49.551.3

51.3

48.948.848.8

21.7

43.914.4

29.1

43.9

W/cm2

57.057.057.0

57.0

57.257.2

58.958.930.5

58.460.5

60.5

57.6

57.557.525.6

51.9

U.O

34.351.9

G

kg/m s

701

756805

795785788798

783757750

765813

701

747781

524687547547547

xex

17.716.3

15.3

15.515.715.715.916.2

16.8

16.8

17.2

16.1

17.8

16.7

15.s10.2

16.3

7.c15.724.3

Steady state measurements

C-f(Q) Burn-out

Pres-suredrop

404133

404134

Temp,distr.

405120

405121

Voiddistr.

413127

413128

413129

413130

413131

Dynamic measures»

Noise Step Biniper"bat

461

461

461

461

461

461

461

461

461

461

461

461

462

462

AS:

F « Forced circulationN » Natural circulation1) Experiment interrupted because of instability2) Experiment interrupted beoause of burnout

(Cont'd) Second test period

ofo i r o .

FF

FF

F

FFFFFF

FFFFFFFFF

k i nv .h .

H

m

6.5c6.50

6.50

6.50

6.50

6.506.50

6.50

6.50

6.50

6.50

6.506.50

6.50

6.50

6.50

6.50

6.50

6.506.40

Loop 000ditions

P

bars

69.569.2

69.469.2

69.2

69.2

69.2

69.2

69.369.2

69.5£.2

69.6

68.7

69.269.2

69-2

69.2

87.3

87.3

AS .sub

°C

2.6

3.32.82.8

3.33.33.3

4.53.8

3.53.52.52.3

25.549.2

21.522,524.64.02.8

Q

kW

40135342

50245898

5024

619750245024648668607140

73376053573350246642

7129637349524513

(Q7I)

W/om2

59.0

78.473.886.6

73.891.073.8-3.8

95.2

100.7104.8

107.769.084.273.8

97.5104.793.6

72.766.4

W/om2

69.6

92.587.O

102.2

87.O

107.487.O87.O

112.3118.8

123.7127.1105.0

99.487.O

115.1123.5110.4

85.8

78.4

0

kg/m 8

601556556712

715862863

10131012

1217

14451790

1871

497726736

849608

564690

xex

i30.1

43.441.c

37.431.432.1

25.*21.428. i

24.52 1 . É

18.1

14*^

44.725.534.431.240.242./

31.1

Steady s tate measurementt

G-f(Q) Burn-out

403106

403107

403108

403109403110

403111403112

403113

403114403115403116403117

Pres-suredrop

Temp,dis tr .

Voiddis tr .

413132

413133

413134

413135413136

413137

413138

413139

fynamio measuvemc

Noise Step Bintperlbat i

F • Forced oiroulationW •. Natural oiroulation1) Experiment interrupted beoause of instability2} Experiment interrupted because of burnout

Appendix 1. (Gont'd) Seoond test periodA25

Loop conditions

c ire.

P

P

P

P

P

P

P

F

P

P

P

P

P

P

F

F

F

F

F

F

k.in

v.h.

H

m

6.40

6.40

6.40

6.40

6.40

6.40

6.32

6.32

6.32

6.00

6.00

6.00

6.00

6.00

6.00

6.05

6.05

6.05

6.05

6.00

P

bars

87.3

87.3

87.3

87.3

87.3

87.3

86.8

86.8

84.O

50.3

51.8

50.3

49.8

50.3

50.350.1

50.1

50.1

50.2

50.2

sub

°C

2.8

3.1

3.0

2.9

2.0

2.0

2.3

2.3

4*0

3.2

3.6

3.3

3.0

2.8

3.3

25.0

23.0

23.524.2

21.5

Q

kW

5270

5620

6053

6404

7140

6901

5024

2990

0

5805

6342

6870

7037

5024

5024

6508

7089

5497

6115

6829

(Q7A)

W/cm2

77.482.5

88.9

94.0

104.8

101.3

73.8

43.9

0

85.3

93.1

401.0

103.2

73.8

73.8

95.5104.0

80.7

90.0

100.2

W/cm2

91.3

97.4

104.9

110.9

123.7

119.587.O

51.9

0

100.5110.0

119.0

122.0

87.O

87.O

112.8

122.8

95.3

106.0

118.3

0

kft/m s

688

852

1138

1398

1763

1600

1606

981

995

587

727

9741095

715

533

590

735420

541

698

Xex

37.3

3 1 . *

25 . !2 1 . t

19 c

20. *

14.1

14.3(

41.3

36.6

29.1

26.529.2

39.3

39.7

34.4

48.9

41.4

37.S

Steady state measurements

G-f(Q) Burn-out

403118

403119

403120

403121

403122

403123

403124

403125

/">3126

403127

403128

403129

403130

403131

403132

Pres-suredrop

404135404136

404137

Temp,distr.

405122

Voiddistr*

413140

413141

413142

413143

Eynamic measuremo

Noise Step Binapertbat i

P • Foroed circulationK » Natural circulation1) Experiment interrupted because of instability2) Experiment interrupted because of burnout

Appendix 1. (Cont»d) Seoond test period

TVpeo fciro.

P

P

P

P

F

P

P

P

P

P

PP

P

P

k.S vti n

v.h.

•

H

m

6.00

6.00

6.01

6.01

6.01

6.01

5-975-98

5.98

5.97

5.97

5.975.975.98

i

Loop conditions

P

barsi

30.2

30.030.2

30.2

30.2

30.0

30.1

30.2

30.2

30.2

30.2

30.3

29.529.6

fisUU

°c

3.32.6

5.13.73.72.63 .0

3.0

2.8

3.1

24.725.2

0.5

0.5

Q

kW

5641

52296280

66747068

72242990

2990

4513

451329902990

0

0

(q7Dp

W/om

82.976.8

92.398.0

104.0

106.0

43.9

n.966.466.443.943.9

0

0

^/AUxU1Q.JL.

O

W/om

97.790.6

109.0

115.5122.5

125.0

51.951.978.478.451.951.9

0

0

GP

kg/m 8

586

512

740

886

10271140

51411101088

755

1045514

5371562

Xex

i36.739.131.8

28.425.8

24.1

21.9

9.715.522.5

4.716.2

0

0

Steady state measurements

C-f(Q) Burn-out

403133

403134

403135403136

403137403138

Pres-suredrop

404138

404139404140

404141404142

404143

Temp.distr.

405123

405124

405125405126

405127405128

405129405130

Voiddistr.

413144

413145413146

413147413148

413149

Dynamic measurenu

Noise Step

-

Bin*perlbat i

P - Foroed circulationN « Natural oirculation1) Experiment interrupted because of instability2) Experiment interrupted because of burnout

L « 9 0 0 -

CONDENSER

L 10120P30

L7A00

L 5900-

Manometer (Ml

LS620

L:L»v»l indication pressure tap

P » Pressure tap

t 7120

5623

i sti—*

L 4200

1200Vtnturi flow m»Ur -

177

Oriflc* plat* flow m«t«r

Electrical(only for »tort up)

\

Water forregulation ofsubcooling

2300

STEAM SEPARATOR

•795A

6954

-59K

L5410

Outletinstruments

5010

4365Upper endof heatedlength

227

TEST SECTION FT-36b

Drag body flow meter(RAMAPO)

Lower end of~ w heated length

Fig. 1 - Geometrical data In mm at 20 °C for the FRI6G loop.

69M(69S4)

9131 (5914)

Turbin* flew meter— 5*00 (4985)Impedance »eid 4895 (4660>

4435(4*15)

(4365)

End of cluster

End of he att dlength

66

65

3535(3525)

3045(3036)

64 2387(2380)

63 -1925(1920

62 1288(1284)

61 821(819)

Start of heatedlength

414(4401)4273(4261)4119(4107)

2878(2870)

2709(2701)

G i Gamma void stationP« Pressure tapT sThermocouple

—H Position i mm at 260 • C (20»C)

2158(2152)

2000(1994)

4778(1773)

0604)

1368(1364)

1058(1055)

900(897)

508(507)

413(412)

177(177)

Fig. 2 - 36-rod test section FT- 36b

Unheated ctnttr rod

Fig. 3 - Cross stctten of FT »36b

Electrical connection of the heater rods at the upper end of thetest section. The silver wires (right) displayed a more regularpattern after some time at power due to the electromagnetic forces.

Lower end fitting of the heater rods and theburnout detection leads.

Fig. Details of FT-36b.

t

CM

1

i

it

3y«bol

0«

•DAV

Ron 16

401113-123401124-135401136-148401162-173401174-185401186-195401196-204

Motion

FT-36bM

t !

I t

H

H

I t

5.9N

t t

M

ni t

I t

inT.h.

14.013.413.7

5.121.4

131261

bara

49.749.949.849.949.749.749.9

BUD

3.06.6

15.03.02.82.93.0

baoauaa of

Burnout at 6150 kW" 6260 kW

Inatcb. at6O5O kW" 5900 kW

Burnout at 6110 kW" 5280 kW" 4670 kW

1000

600

Efftot of inlät suboooling, k. »14 v.h.

liaito*t forood

circulation

1000

800

600

400

200

Bfftot of inlat throttling, ^V^^l

i y4.0 v.h.Oy,

21.4 v.hP

-

»1 V.ll .^

i

o-—o—o*

A—*—*-

i

w V If

1

r ©CI . 1 ' 1

f BMrnout l iait•iMWid at forood1

eiroulation

J J ^ N ^ ayk

^v Prodioiod burnowt\ l W t (loakar)

-

i

20 40 60 80 100ATtraga surfaoe haat flax, (Q/A)

1202

140

20 40 60 80 100 120

Powtr dtniity, Q/7, kW/lit. •140

0 1000 2000 3000 4000 5000 6000 7000 8000 9000Haating powtr, Q, kW »

. 5 •' latural oiroulation eurraa obtaiaad at 50 bara with 36-rodtaat aactioa FT-36b. Iffaot of inlät tuboooling and tfftotof inlät throttling.

Symbol Run No T»8X

sectionH

T.h.P

bars •C

Exp. interrupted

because of

o

«

401237-250401113-123401205-214

301001-016301042-047

FT-36*bit

H

5.9II

n

FT-36a 5.9

13.314*013.6

13.8

29.849.769.5

50.0

3.03.02.8

4.6

Instability at 4290 kWBurnout at 6i5OkW

" 5880 kW

" 6400 kW

1000

t800

600

CM

$ 400

Effect

P, bar

29.8

49.7

69.5

-

of pressure,

•

X

1

i

FT-36b, k. sin

X

\

"*""*X

*• 14 v.h.,i

//

\

sub15*

Burnout ]

3 °C1

• KMIv

1

m

tiait at p*30 barat

A\? = i « c , —••writ at\foreSS8 eiroulation

I ' '

20 40 60 80 100 120 140

o 1000o4

A 600

600

400

r0

Comparison between FT-36a and FT-36b, k » 14 v.h. , pi»50 bars, ^1^ufeÄ3°C

/

~—B

1

FT-366

k«rt • '•• •

1

1

^ ^ ^ ^

1

-•1

- ^

out

1

1

1

*mo»t

y7

l\

•

-

\ v \ £xtr^ol*t#d\ \» t^ i l i ty HmiU

120 40 60 80 100 120 140

Average surface heat flux (q/A), W/c

—r~40 60 80 100 120 140

Power density, Q A I kf/lit

, , , , ,1000 2000 3000 40000 5000 6000 7000 8000 9000

Heating power, Q, kf •>

. 6 . latural circulation ouzree for 36-rod olusters.Effeot of pressure. Cosiparison between FT-36a and FT-36b.

900

800

700

6001100

X

•

o x

— # —

• xo

O IT—€hm k ."0out

FF-»3^bt k •••1»0 • •

•

1000

w 900

800

700

1000

QA - 50 kW/l

> *

900

a 800

I,ao

i700

600

Fif. 7

Q/7 . 80 W/lI

10 15 20fcilet throttUne,

25

Natural circulation mass velocity verstis inlet throttling atthree different power densities* Comparison between 36-rodtest sections PT«36a and JT-36b, and 6-rod test seotlon FT-fb. j

•av-V*, S^i.iK--- ?^!f***TR«

12

8

Bolt» -eoording lo 450101-110Natural oirc. n a lo 401113-123

- 14*0 T.h.f p - 49*8 bars

1

•

•

f

•

•

1

0,3 - 1 cps-

Rough.estimate •froa Sanbornreoording

/

/^ w i

12

8

A

4

0

w

•

0

1

1

<

1

^1cps

•

•

-

8 012

8

8

löiee reoor&inff lo 450141*154latural olrc. ron lo 401162-173

j#1 T.b.f p - 49.9 bars- 3.0 °C

1•

1

•

•

1

•

• •

0.3 - 1 cps

-

-

tstrapolated etability limit Extrapolated stability limit

(aaa» mine) 6.52 MW (mean value) 5.79 MW

Fig. 8 . DETERMIHATIOI OF STABILITY LIMITS BT MEANS OF PLOW NOISE ANALYSIS.

12

8

1

1

-

v .• \

•

1

vXX

1 cps

-

--

1

8 012

8

8 0

lolee reoordimc *o 450155-163Natural ciro. ran 16 401174-105

imm 49*7 bar»

11

1

•

B

1

• •

i

1

0.3 - 1cpa

m

81

•

•

•

1

*

• 1

1

^13pa

•

k:8

Extrapolated stability limit

(mean ralue) 7.50 M»

50 BARS.

t

3

•P

åOOo

140

120

100

80

<

Å

in •

;

BUD

4

Legendt

o PT-6b,

• FT-6b, k .-0.6 v.hout

FT-36t, k .«1.0 r.h.ouxBest-eye-fitourves toFT-36b points

20 30 40 50 60 70

Pressure, p, bars •

80

t

1dO

120

100

80

Effect

O

A-

#

Of

X

inlet suboooling, P»

i

50

i

bars,

— —

kin*14

0

v.h.

10 15 20

Suboooling, Al/ , °C

25

140

ti100

60

Effeot of inlet throttling, p«50 bars, &1? . Ä 5 °C

o

10

30

15 20 25 30

Inlet throttling, k. , r.h< »

Fig. 9 * EXTRAPOLATED STABILITY LIMITS POR 6- AKD 36-ROD TEST SECTIONS.

Tvtmeno* mm

Tig. 10 - nCORDIRO OP fLOf AID TDID 5I01ALS fOB A CAS* JUM AJ0T1 I D

a M

Positions of besås for roid »isasursBtnts,

ror1

P2

r3r4

> 10.0

- 21-.60

-41.73

• 62.20

- 79.75

Pig. 11 - ZONE DIVISION FOR EVALUATION OF RADIAL VOID DISTRIBUTION.

100

80

• i r

Riser turbine flow meter

i i i i i i i

25 30 35

Modified Martinelll-Nelsoncorrelation (ref. 17)

Not plotfd

H J5 26 »C tube.

30Channel meanconditions

, u b 4 3#C av specified

10 15 20Steam quality, x, 7.

500i » . W i i

1000 1500 2001Mass flux, kg/m2» w

Fig. 12 - VOID FRACTION VERSUS STEAM QUALITY AT 50 BARS. CROSS SECTION MEAN VALUESAT POSITIONS G1-G6. FT-36b.

-4 a 10 15 20Steam quality, x (•/•)

25 30

100

1oc2,(FT-36a)

15 20 25Steam quality, x (•/•)

Fig. 13a - ZONE MEAN VOID VERSUS RADIAL MEAN QUALITY AT -50 BARS,

ZONES 1 AND 2. POSITIONS G1-G6. FRIGG F T - 3 6 b .

(See symbols fig. 12)

oC, .(FT-36a)

15 20Steam quality, "x (•/•)

15 20Steam quality, x (7.)

Fig. 13b - ZONE MEAN VOID VERUS RADIAL MEAN QUALITY AT -50 BARS,ZONES 3 AND A, POSITIONS 01-06, FttlM fT - l »b .

symfc *§ fig. 12)

%I

i4j/y

15 20 25Steam quality, J? "/•

15 20 253ttam quality, I •/.

100i i i i

13 20Steam quality, x */•

25 10 15 20 25Steam quality, x '/•

Fig. U - Comparison of zone void vs. mean quality for the different pressures. FT-36b.(Best-eye-fit curves).

50 barsFT-36a

Fig. 15 -

20 25Quality, x, •/• —

Best-eye-fit comparison void vs. quality,cross section mean values, FT-36b.

30 bars, (2 runs)

70 bars. (2 runs)

0 5Cross section mean quality, */•

Fig.16 - 50 bar void compared to 30 and 70 bar voidsin the subcooled region. FT-36b.(see symbols fig. 12)

80• Run No 413117

G - 520 kg/m2s

qTÄ « 43.9 W/cm2

100

80

60Run No 413116

6 a 1020 kg/m2s

qTÄ * 43.9 W/cm

Zon»

280

60

40

20

-50-5

<;>

80

60

L Run No 413112

6 - 994 kg/m2s

qTÄ > 66.4 W/cm2

(Subc. «• 15 «C)

No 413114

O* 2045 kg/m2»

qTÄ*66.4 W/cm2

St*am quality, '/•

80

40

20

ÉRun No_

6 > 2045

qTA . 89

•

| I t 1

413115

kg/m2»

W/cm2

/ \

•

-5

Fig. 17 - Comparison zone voids vs. mean quality in the subcooled region. 50 bar runs. FT-36b.

T * 28 ° C ) - (Best -

D

Run No

31301$413116

Test Mdion

FT-36OFT-36b

•C19.325.8

<*M

W/cm2

42.643.9

6

ka/m2»12061020

100

80

:• 60

if40

20

Zon» 1 1

/

-5

T T

4

/

J I I I

CM

Zon» 2 i

-

•

i • 1 I

// j• i • i

I

100

80

Zon» 3 !i T r

40

20

Zone 4 |i i i i i

-

-

-

i i i i

-

-

D

D

i i i i

S C/.). (%)

Fig. 18 - COMPARTIVE RUNS FT-36a/FT-36b. SUBCOOLED VOIDS. 50 BARS.

Syntboi

L6

Run No

313020413113

Tt»t Motion

FT-36oFT.365

•C

2?.425.t

q/AW/cm2

64.666.4

6

11581020

Fig. 19 - COMPARATIVE RUNS FT-36a/FT-36b. SUBCOOLED VOIDS. 50 BARS.

10

>

k

¥ |

• •

i • 1 •

i i i i

• • •

1 •

* • *

m 1

f ¥ ¥ »

• • • >

0.1 0.2 0.5 1.0 2

B» • 10~5

I

10

Fig. 20a - PRESSURE LOSS COEFFICIENT FOR TEST SECTION INLET. FT-36b

P12-P15

:o

2

-

1

1 I

1 1

1 fc 1 1

• mé

• i f I

•

1 1

* r *

i i

• i • •

•

0.1 0.2 0.5 1.0 10

R* • 10"

Fig. 20b - PRESSURE LOSS COEFFICIENT FOR PART OF -JHDLE INCLUDING SPACERS

FT-36b.

i

•S 0.1 0.2

0.05|

0.02

0.01

P2O-P21

•

9 1

1

1 1

I I I '

* * * t

1 » • I

f-0.2 ET0'2

/

• f * '

0*5 1.0 2 5

Rt • 10"510

Fig. 20e - FRICTION FACTOR FOR SMOOTH PART OF ROD BUNDLE. FT-36b

1.0

o — 0 - 5

ii0.2

I °*0

i

• • 1 • 1 • • 1

• •

/

fett valu»

• • • •

m

^fev «

0.1 0.2 0.5 1.0 2.0

Re • 10"5

5-0 10.0

t»

Fig. 21a - PRESSURE LOSS COEFFICIENT FOR SPACERS. FT-36b.•O 2Using f - 0.2 Re * for smooth stretches of bundle.

i\ 2.0

i.o -

• (x's jfor 2nd tes1

• • I I

• • •

t period)

1 1 É t

• 1 • 1

1 p 1 i

0.1 0.2 0.5 LO 2 5Re • 10"5

10

Fig. 21b - PRESSURE LOSS COEFFICIENT FOR TEST SECTION OUTLET. FT-36b.

(Including spacer, cables, expansion).

I 0.2

•

1 1

*

I I » *

• • - c .

I 1 1 1

%

•

1 1

•* i •

i i • •

• m

i • i i

0.1 0.2 0.5 1*0 2

• 10"5

10

F i g . 21c - PRESSURE LOSS COEFFICIENT FOR OOfURP UÖTBÖMEIWPATIOI.

10

i• 5

©oonooS 2o

1©

•

•

••

-

•

• •

•

•

1 1

1 I I I

-

1 1 1 1

10

Re • 10-5

Pig. 22 - PRESSURE LOSS COEFFICIENT FOR STEAM SEPARATOR. FT-36b.

0.3

0.4

0.3

0.2

0.1

»un 16 404131p - 69#2 b u t

100

80

• I

40

20

2.0 3.0

HBÉJP&D LBIGSTH

4,0 5.0 •CHAHSEL

Fig. 23 - CROSS SECTION MEAN VOID AND PRESSURE DROPS - PARTIAL AND TOTAL -

VERSUS CHANNEL LENGTH FOR RUN No 404131. FT-36b.

•ti

k

i

Test

section

FT-36*

Circu-

lation

Forced

Pbars

»30«*50»70

°c2.8-25.21.9-20.42.8-16.0

(Q7Ä)

W/c*2

21.7-66.421.7-89.022.0-66.4

6

k«/»28

514-1110488-2046500-1968

30 p » 30 bare |

o 51410 5 524 kg/m •

• 687<G*755

Martinelli-Nelsoncorr.

Best-eye-fit curves

CM 20

U•HiHP.•Ha 10

s

p - 50 bars

o 488&G<520 kg/m s• 729 i G < 830 "

19764 Gi 2046

P.

Becker corr.

Martinelli-Nelson corr.Best-eye-fit

curves

o G - 500 kg/m a

7461. G i 1050 "

G -1968 "

Becker corr.Best-eye-fitcurve

Martinelli-Nelson corr.

15 20 25

Steam quality, x {%)-

30

Tig. 24 - TWO-PHASE FBICTIOI ÄILTIPLIER FOB SMOOTH PART OP ROD BUNDLE.

30, 50 AID 70 BARS. FT-56b.

1.9-30.42.8-16.0

21.7-66.421.7-89.022.0-66.4

5U-1110488-2016494-1968

30

20

10

p - 30 bars

o 514^C5 524 kg/m2n

• 687 50*771 "

*1044 * G * 1110 •

Best-eye-fit curvesMartinelli-Helson oorre1.

CM

feQ»

•H4»

20

i 10

§4*O

£

p * 50 bars

o 488^0*520 kg/m2B

' A 991 <=G£ 1086 "

o

rT /

I Best-eye-fit\/s | curves V

\\ Martin«lli-

\Heleon oonel . -

10 15 20 25 30

i 20

10

p • 70 bars |

o 494* G i 500 kg/u2 s• 949- G^ 1050 tf

A G.746 »x G-1968 "

^ ^ ^

_ .

\Best-eye-fit ourres

\ ItortlM i l l -A correl*

f10 15 20

Stea» quality,

25 30

71*. 25 - TfO-FHASE TBICTIOi MULTIPLIER AT 30, 50 AID70BAHS TOR SMOOTH PARISASSUMHG THE HOMOGEIOaS FLOf MODEL TO BE 7ALID 70S THE SPACER»,TT-36b.

Test

••ction

FT-56b

Circu-lation

Forced

Pbara

Ä30Ä.50~70

*^aub

°C

2.8-25.21.9-50.42.8-16.0

(*/A)

W/c«2

21.7-66.421.7-89.022.0-66.4

G

kg/»2»514-1110488-2046495-1976

50

20

10

p - 50 bars

0 514 G5 525 kg/m2s

- • 686 <G* 770 "

»1045 5G< 1110 "

-Hartinelli-Helaon corr.

\ £2-1+x(-

0

-

-

-

10 20 25H

CM <J)

20

•H4»V—•

8 10§•HO

i

p

0_ •

XA 1

- 50

750 s991 <

bars

• GS85OG^1086

r

It

•t

I

Martinelli-Nelson corr.

o

i

5 10 20

20 p - 70 bar»

"o 495*G<500 kg/m B

A G -1976

Kartinelli-Hel8on corr.

10 15 20 25Sttaa quality, x(

7if. 26 - TWO-PHASE FRICTIOI MULTIPLIER FOB TEST SECTIOH OUTLET.(IICLUDIIG SPACER,CABLESfEXPAWSIOl). 50, 50 AND 70 BARS.FF-56b.

50

50

Test

section

FT-36b

Circu-

lation

Forced

Pbars

**30"-50~70

°c2.8-25.21.9-30.42.8-16.0

(q/A)

W / c '

21.7-66.421.7-69*022.0-66.4

6

514-1110488-2046495-1976

p :• 50 bars

O 488i: G* 520 kg/nBe8t-eye-fit curves

f-

p - 70 bars

o 495 - G* 500 kg/m s• G-745 "x 95O^G^1O5O "A G-1976 w

Best-eye-fit curves

20

Steaa quality,

27 - TfO-FHASE FRICTIOI MULTIPLIER FOR OUTLET IIBTHUMKITATIQV,

30, 50 AH) 70 BARS, FT-36b.

Best-eye-fit curves forsmooth parts (Fig. 24)

Martinelli-Nelsoncorr.

Best-eye-fit curves for smooth parts usinghomogenous multiplier for spacers. (Fig. 25)

Fig. 28a -

10 15

Steam quality, x

THE EFFECT OF ASSUMING THE HOMOGENOUS FLOW MODEL MULTIPLIER

FOR SPACERS. 50 BARS.

CM

P.•H

8§4»O

i

Mass flow oorreotedMartinelli-Nelson corr.(KAPL-2206)

Becker corrMartinelli-Nelsoncorr.

Best-eye-fit curresfor saooth parts (Fig. 24)

Fig. 28b

10 15 _ 20Stean quality» x,(?O

TWO-PHASE FRICTION MULTIPLIES MASS FLOW DEPENDENCE.

50 BARS.

Square waveJ <5Q = t 2 5 - t 5 O k W

001 002 003 005 02 03 OS UO 2AFrequency, U, c/s-

Fig. 29a - TRANSFER FUNCTION FOWER-TO-MASS VELXITY AT 3000KW. INFLUENCE OF SYSTEM PRESSURE.

Y=-

o

dun

462162

J6212L

462018462004462019

T»tlsection

Perturbation

kW

7100

110013.68

13.6191.2

Sampling

At»s

0.140.18

0.6

0.180.6

c/*

3.01.0

0.33.01.0

0.3

kin

13.3

Pbars30.230.0

49.4

•C

2.8

3.02.8

2.01.7

Loop condition»

299O

3008

43.9 762766J*.757828824

T4T?14.5

14.7U.915.O

IS"87

"5T81

Square wave±25-±50kW

30» 1 • • 1 I 1 1

05 10Frequency, >) ,c/$

Square wave

Q=±25-±5OkW

001 002 003 005 04 02 03 09 ^ 10 10F

Fig. 29b TRANSFER FUNCTION POWER-TO-EXIT VOID FRACTION AT 3000 KW. INFLUENCE OF SYSTEM PRESSURE.

05 10Frequency, 0 ,c/s

002 003 005 OS UOFrequency, \>, c/s-

Fig. 30a TRANSFER FUNCTION POWER-TO-MASS VELOCITY AT 4500 kW.INFLUENCE OF SUBCOOLING.

462103 FT-56b tipp

05 UO 'Frequency, ,c/s

ÖT 10Frequency, »>, c/»*

30b - TRANSFER FUNCTION POWER-TO-EXIT VOID FRACTION AT 4500 kW.INFLUENCE OF SUBCOOLINO.

Yr * 6 / G

' <5Q/Q

tnmhfll

v4

••D

0

•

KunN»

362017362016362015362014

_4J41

MCI ion

«

H

kW

-120

^vTHHI 1, AMI KF51«004

462019462043462036

I I

I I

«

M m

N

19

•

i

T•

5*32_13.6a

I I

91.2?'#

13.6891.25.32

13.68

Atts

0.140.18

«

0.60.140.180.60.140.18

c/s

3.01.0

• i

0.}3..01.0

0.33.0

1.0

kin»K14.0

M

N

m

1}.OI I

H

m

N

Pbor»

50.0n

I I

H

49.249.4

49.8n

AtTtub•c4.6

N

N

«

2.01.7

N

5.9M

Q

kW

2810«

2815«

3008n

N

N

H

(•VA)W/em»

41.1n

41.2N

44.2M

n

M

*

6kg/n?»

886N

M

«

621824820813

n

%

12.1N

12.2N

15.0n

15.114.0

11

«•*

%

-10

/

/

/

-15

-20

007 003 005 05 ID /

Frequency, 0 ,c/s

FT-36a,l^0v.h. jA&^

FT-366,^1X^.0.^^2

b h j 5.9*C

002 003 005Frtqutncy, \>, c/s

Flg. 31 TRANSFER FUNCTION POWER-TO-MASS VELOCITY. COMPARISON BETWEEN FT-36a AND FT-36b.

Y=$0/G

6Q/Q

35

30

ID25

20

15

10

462167

stction

FT-36bkW

125555" Ji. 13.66

At»

0.16c/s1.0

kinv.h.

T—r—r

Pbors

30.230.1

•c

2.8

Q

kW

33213331

W/ccn»

48.848.9 795

' • • ' I

1 5 . 6

Square wave

4Q=±15-±100 kW

T—i I I i i 111

. . • i . . . .

03 1.0Frequency, 0 ,c/s

002 003 005

Square wave

±15-*100kW

' • ' i i • • • •

002 003 Frequency, U, c/*-

Flg. 32a - TRANSFER FUNCTION POWER-TO-MASS VELOCITY AT LOOP CONDITIONS NEAR THE STABILITY LIMIT.

L

lOr-r

Symkol Run

46216?

462165

T»SIsection

FT-36b

4QkW

• 6C19 13.61

Sampling

At»»

0.16e/»

1.0

kinv.h.

4.6

Pbor»

30.230.1 2.8

Loop condition»

3321

3331

W/km»

48.848.9 795

15.615.0 68

Square wave&Q=±15-±100 kW

002 003 005FrequenqV, 0 ,c/s

Square wave= ±15-t100kW

002 063 006 0.1 02 03 05 10 10Frequency, t>, c/s-

Ffg.32b - TRANSFER FUNCTION POWER-TO-EXIT VOID FRACTION AT LOOP CONDITIONS NEAR THE STABILITY LIMIT,

•» I I I I I I I I I I > > I I • i • M M •< I I I I M i > t I t t M i-» -I I < t >• t

27 puleeg/sec

430 pulses/sec

\ 1

— . . . .

A i

. ._. .

TURBINE FLOW METERl

Run No

46.2i6i_

-V--y.h.^4.6 .

bars

. 1O._1

o C

2.8_ _

. Q

kW

.3330

G

kg/m 8

795

ex

15.6 88

Extrapolated stability limit Q * 3400 --100 kW

VOID FRACTION

MASS VELOCITY

M S / " I/ V T"V S/W •-\ SJ WIf

I " •v

t

j M N

,_1.2Q kW

i (•• i

I

Fig. 32c . RECORDING OF SIGNALS FOR A CASE AT LOOP CONDITIONS NEAR THE

STABILITY LIMIT. (Filter break frequency V B - 1 o/e)

oaX

0.60

iO 050zLU

(A50.40O

m

0.20

0.10

0

Ip (b<

X 30^% d u

O 50A 70D 90

ä

ars)

C

A

fr*AXD

(P

9 c

X

O

1

BURNOUT PARAMETER,

Fig. 33 - MEASURED LOCAL BURNOUT CONDITIONSFOR FT-36b.

1800

40080 90 100 110 120 i:

BURNOUT MEAT FLUX, (q/A)BQ (W/cm2)

Fig. 34 - MEASURED BURNOUT CONDITIONS FOR FT-36b.

CM

O

O 600A 1000

50 70 90PRESSURE, p (bars)

Fig. 35 - EFFECT OF PRESSURE ON BURNOUT.

5050 60 80 100 120

PREDICTED BURNOUT HEAT180

Fig. 36 - COMPARISON BETWEEN MEASURED ANDPREDICTED BURNOUT CONDITIONS FOR THE36-ROD BUNDLE FT-36b (HAVING RADIALFLUX PEAKING) ACCORDING TO BECKER (Ref. 32)

36-ROD BUNDLEA UNIFORM HEAT FLUX (FT-36a)O NON-UNIFORM HEAT FLUX (FT-36b)

60 80 100 120PREDICTED BURNOUT HEAT FLUXffr|/A)B0(W/cm2)

Fig. 37 - MEASURED AND PREDICTED HEAT FLUXES FORTHE 36-ROD BUNDLES FT-36a AND FT-36bACCORDING TO BECKER (Ref. 32)

, j

(O

"E IOOO

I

p s 50 bars

i

D

o

tu

</> 500

COD

O UNIFORM (FT-36a) 5.5 ± 2A NON-UNIFORM (FT-36b) 8.7 t 0.7O NON-UNIFORM 3.2 t 0.2

x NON-UNIFORM 23.51 2Oc

Q

2000 4000 6000 8000TOTAL BURNOUT POWER, Q (kW)

Fig. 38 - EFFECT OF RADIAL FLUX DISTRIBUTION ON TOTAL BURNOUT POWEF

900

01

1o

oo

800

o700

600

550

run no

401237- 244bars30

UWsub°c3

v.h.13.3

nm5.9

1

HYDRO(S)RAMONA(N)BOSFLOW (D)

nfeasunements

Q total

6 MWFIG. 39. COMPARISON BETWEEN MEASURED AND

CALCULATED MASS VELOCITIES AT VARIOUSPOWER LEVELS IN NATURAL CIRCULATION

900

800

o

<n 700o

600

run no

401113-123

i»

bars50

nvsub•c3

Kinv.h.14

m565

- ~ HYDRO(S)RAMONA (N)BOSFLOW(D)

measurements

Qtotal5 5 0 1 2 3 U 5 6 MW

FIG. 40. COMPARISON BETWEEN MEASURED ANDCALCULATED MASS VELOCITIES AT VARIOUSPOWER LEVELS IN NATURAL CIRCULATION

01CM

O

uo

(AO

900

800

700

600

550

run no

401205- 214bars70

•c3

II i

v.h.13.6

m5.9

^-measurements

HYDRO (S)RAMONA(N)BOSFLOW(D)

Qtotal

1 6 MW

FIG.41. COMPARISON BETWEEN MEASURED ANDCALCULATED MASS VELOCITIES AT VARIOUSPOWER LEVELS IN NATURAL CIRCULATION

900-

800-

700

60C

50C

mm BO

401237-244

bart

50

IttD

3

• . h .

13.3

•

5.9

J I I I I I

Run Mo

401113-123

bars

50

""aub°C

3

"inv.h.14

u

5.85

Experiments

HTDRO-calculations

10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80• — - 2 _.-m Aytrage heat flux, qjk,

1000•HOOH

S 900

800-

600-

500

Run l o

401205-214

Pbara

70

^ 8 t t b°C

3

kiny.h.

13.6

H

•

5.9

700-A

Run No

401136-148

P

bara

49.8

^ . u b°C

15

k i nT.h.

13.7

H•

5.9

I I J I

10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80

»• Areragt haat flux, q/A, f/«i — — ^

I Fig. 42 - COMPARISON 0? THE MASS TELOCITY AS A FOICTIOI OF POWER II IATORAL

I CIRCULATION WITH HYDRO CALCUUTIONS ASSUMING A THROTTLING OF 4.0

i — . . .

No

462015

section

FT-J61kW

1100 5.32 0.14

»oc/s3.0

v.h.

13.c

bars

49.2

»»UD

C

2.0 3008

W/fcm*

44.2ko/rrfs821 15.0

V ~ —-"

ta/o

462004 13.6C 0.18 1.0 49.4 1.7462019 91.2 0.6 0.3 49.3 620 15.1

CD"O

O(9

001 0D2T.' - 003• • • • *

50i-r

Q05 0.1 0.2 0.3 05 1.0 t 2X)Frequency, 0 ,c /s -

-250

. 3 0 0

Experimental resultsHYDRO-calculations, ( e a s e l )

RAM0NA calculations, constant pressure (case 2)

„ „ .variable „ (case 4)• „ „ , constant „ , sinosoidal perturbations (case ZY

1 1 1 I . I . . . I 1 1 1 1

001 OK» 003 005 0.1 02 013 05 10Frequency, iJ, c/s-

2.0

Fig. 43 - TRANSFER FUNCTION POWER-TO-MASS VELOCITY AT 50 BARS AND 3000 kW.COMPARISON BETWEEN MEASUREMENT AND CALCULATIONS.

o

•p

90

80

70

run no

413146

413147

413148

fbars

30

30

30

°C2.8

3.1

24.7

(q /A)W/cm2

6&4

6E4

433

Gkg/nrls

1088

755

1045

S\measure-

ment

0

X

+

rmbolcalcula-

tion

. _

BOSFLOW (D)

RAMONA(N)

HAMBO (S)

BOSFLOW (D)

HAMBO (S)

RAMONA(N)

RAMONA(N)

HAMBO (S)

BOSFLOW (D)

channel lengthl

1

Fl G. 44. CHANNEL MEAN VOID FRACTION VERSUSCHANNEL LENGTH , MEASURED ANDCALCULATED

4 m

o"oq

TI å

1"90

80

70

60

50

30

20

run no

413103

413109

413116

rbars

50

50

50

uvsub°C3.9

3.3

25.8

W/cm2

66.4

66.4

433

kg/nrfc730

992

1020

measure-ment

o

X

+

calcula -tion

10

RAMONA(N)

BOSFLOW (D)

HAMBO (S)

-

RAMONA(N)

HAMBO (S) BOSFLOW (D)

channel lengthi I

0.25

FIG.45. CHANNEL MEAN VOID FRACTION VERSUSCHANNEL LENGTH , MEASURED ANDCALCULATED

4 m

ö

run no

413120

413125

Pbars

70

70

°c"a3

15.3

(q/A)W/cm2

439

66.A

Gkg/rr?s495

950

remento

X

rmbolcqlcula -

tion

o

80

70

60

50

A0 -

RAMONA (N)

BOSFLOW (D)

HAMBO(S)

0.25 1

channel length

A m

FIG.46.CHANNEL MEAN VOID FRACTION VERSUSCHANNEL LENGTH . MEASURED ANDCALCULATED

run no

Al 3147

P

bars

30

°C

31

q/AW/cm2

66A

Gkgtofc

755

MIXING FACTOR INAND DANISH CALCULATIONSM = 1 0

o MEASUREMENTS CALCULATIONS

90

80

70

60

I 50

40

30

20

10

AYrO

^^

o

ZONE1

B—«=^ .

ngth

- •—

0.5 1

90

80

70

60

50

30

20

10

O

>

>n o

€ 3

^

id kngth05 1 Am

/

o

/f O

/ ^V

ZOf

y\

E2

o

^ *

1

^ ^

cKoni

^—-^

w l It

|

ngth

— —

— —

—»

as i Am

ZONE A AND MEAN VALUES

mtan values, measuredmtan values, calculated

05 1 Am

FIG. 47 COMPARISON BETWEEN MEASURED AND CALCULATEDSUBCHANNEL VOID FRACTIONS. THE CALCULATIONSARE MADE WITH THE SWEDISH AND THE DANISHHAMBO-VERSION RESPECTIVELY

run no

413109

bars

50

°C

33

q/A

W/cm2

66.4

6

kg/m2s

992

o MEASUREMENTS CALCULATIONS

90

80

70

60

150

040

20

10

//

o

D

y \

i—-

ZONE1

clxmnc

* •

0

4len<

- —

. — •

jth-«*

MIXING FACTOR IN SWEDISHAND DANISH CALCULATIONSM =1.0

o

Årf

D0

0

,..—

ZONE2

onne lenj

*——

|th^

05 1 05 1

90

80

70

60

SO\

[»40

30

20

10

7

/Yr

\

s

>

ZONE3

chonneflengt h -

0.5 1 Am

//

V/V

zo

—— 1

D

NEA

meanmean

a.Vs

AND MEAN VALUES

' values, measuredvalues, calculated

ct—i

tonneliens

^ -"

05 1 Am

FIG.48 COMPARISON BETWEEN MEASURED AND CALCULATEDSUBCHANNEL VOID FRACTIONS. THE CALCULATIONSARE MADE WITH THE SWEDISH AND THE DANISHHAMBO - VERSION RESPECTIVELY

i-i- f

Kr.

run no

A13116

P

börs

50

°C

25.8

q/AW/cm2

43.9

6kg/m2s

1020

MIXING FACTOR IN SWEDISHAND DANISH CALCULATIONSM = 10

o MEASUREMENTS CALCULATIONS

I

90

80

70

60

50

30

20

10o

ZON

o

E l

/ r

D

/

/

chain

VTe» 1

>

sngtti

zor

o

E2

o/

Y

chan

^ s

>

rs

0.5 1 05 1o

90

80

70

60

150

ÖAO

30

20

10 o

ZON

o

E3

Å

D

{

——

j

cham

1

W( II

s

ngth

ZONE« AND MEAN VALUES-i—i—v—i—i-

mean values, measuredmean values, calculated

05 1chonnd tenatri —^

i m Ias 1

FIG.49. COMPARISON BETWEEN MEASURED AND CALCULATEDSUBCHANNEL VOID FRACTIONS. THE CALCULATIONSARE MADE WITH THE SWEDISH AND THE DANISHHAM BO - VERSION RESPECTIVELY

xpQexp

X 100(7.)calculated BO: situ:outer subchannel no 8

•10 ••5"

• 5

- 5

-10-

*5

500

a XX

1000 1500+

spc. massf low(kg/m2/s)

2000

~ 3 degC. subcool. 30 barsO

x

AV

3 -8 -

25 -3 -

25 -3 -

50 -50 -50 -69 -69 -87 -

FIG.50-Danish burnout calculations for FRIGG-FT 36b,using HAMBO & BECKERS correlation

if

120

100

80

60

FT-36*. Extr*«Ut*•tftbility liait

N

^ ^O -

\

\

FT-36b. L•Ubility

/

ctr^»Ut«diiait

R-96b. ftmout innatyral eiroMl*tion

ltarvik«n. HM. trtn»i«nt

10 15 20 25

Inlet throttling, k. , v.h.

Pig. 51a - POWER DENSITY VERSUS INLET THROTTLING AT A1/~ v ^ 38UD

COMPARISON BETWEEN FRIGG-RESULTS AND MARVIKEN DESIGN.

50

I140

100

80

60

\

FU3». lateraloiroMUtiow >MrmMt

— —

,

—

\ FT-36fc. Exkr^olfttod\»UWlity lirtt

25

t °C

Pig. 51b -

10 15 20

Inlet subcooling,

POfER DENSITY VERSUS INLET SUBCOOLING AT * l n » 1 3 *•**<

COMPARISON BETWEEN FRIGG-RESULTS AND MARVIKEN DESIGN.

30

FT-36b. ExtrapolaUd atability liait

FT-366. Burnout at naturalcirculation

Mtrviktn. Po««r-pr«aaurarelation &hip in aax. loadadchann«l during start-up

50 60 70

Pressure, p, bars

.4'

Fig. 52 COOLANT POWER DENSITY VERSUS PRESSURE DURING START-UP

OF THE MARVIKEN REACTOR .

1100

1000-

CM

OO

4

Foroad eirouUtion burnout

FT-36b

HYDRO oaleulationa for Marvikanp • 49.5 bara, - 3 °C, k, • 13

Max. tranaiantohannal

CxtraaoUtadstability llaita

FRI66 FT-366p • 50 bara.

40C70 80 90 100 110

Average heat f lux, (q/A), W/cm'•r» P

120

T r T "T"

7 8

Channel power, Q, Wf

. 5 3 - MASS FLOW CURVES POR F T - 3 6 a , F T - 3 6 b AND MAHVIKEH.