Design Activity of High Flux Test Module of IFMIF in Kyushu Univ.

A. Shimizu@Kyushu Univ.

Deuteron beams

Li flow

Test piece

Heat exchanger

Injector RFQ DTL

PIE facilities

Accelerator facilities

Magnet pump

Design & Integration Engineering design over the whole system of IFMIF

Provide 40MeV, 250mA deuteron beam by 2 accelerator modules.

Irradiate D+ beams on Li target with beam footprint of 20cm(W) x 5cm(H)

Remove up to 10MW beam power by Lithium flow of 20m/s

Supply 500cm3 irradiation volume with 1014n/s ･ cm2 (20dpa per year) neutron flux

Irradiation temperature: 250～ 1000℃

Target facilities Test facilities

Neutron irradiation

Test Cell

Qualification of candidate materials up to about full lifetime of anticipated use in a fusion DEMO reactor.

Advanced material development for commercial reactors. Calibration and validation of data generated from fission reactors and particle accelerators.

MissionMission

Outline of IFMIF

Test Cell Configuration

Lithium targetD +

shielding plug

for medium flux region

for high flux regionfor low & very low flux regions

2.5m

Li quench tank

Required performance for temperature control in He-cooled high flux test module

Irradiation characteristics has strong dependency on temperature.

Specimens must be kept at a constant temperature (250-1000℃) with acceptable error of less than 1%.

Space for cooling channels, heaters, insulations etc. should be minimized.

Small irradiation volume of about 0.5 l must be assigned to specimens as large as possible.

The temperature control for specimens in HFTM is one of the most challenging issue in IFMIF project!!

Test PiecesCapsuleGap

Rig

T.C.

Original design of test module

Large uncertainty of temperature measurement

• Large uncertainty of temperature measurement is inevitable due to gap conditions and location of thermo-couple, if the T.C. is buried in capsule.

0 0.2 0.4 0.6 0.8 1

40

60

80

100

120

Re=124000, P=0.9MPa

parameter f

tem

pera

ture

dif

fere

nce

T

[K]

0.25mm 0.75mm 1.25mm 1.75mm

location of T.C. in Capcule

Estimation of uncertainty oftemperature measurement

Effective gap conductance gap varies as function of parameter f.

f means the volume fraction of occupation of gas (He) in the gap.

f =1 when the gap width is retained, but f can be change, for example, due to swelling.

HePTgap

ff

..

11

Buried location of T.C. from the capsule inner wall

T.C. can not measure (estimate) the temperature of T.P. due to non-uniformity of temperature in T.P. and inherent uncertainty of measurement procedure.

Change in design & derivation of HFTM

• Ultimate purpose of HFTMTemperature control for irradiated specimens for lo

ng time periods in temperature window of 250-1000 deg. C with adequate volume for specimens.

• Uncertainty of gap condition between specimens and capsules makes identification of specimen temperature very difficult.– Temperature difference of 100 K or so between actual an

d guessed temperature in specimens arises easily.

NaK-bonding (EU) & He-bonding (JP) concept

Features of both design

• NaK-bonding concept (EU)– Problem originated from gap condition is overcome due to h

igh thermal conductivity of NaK filling the gap. Other problems arise

– Nak is available only under 650 deg. C.– How to fill NaK into the gap of 0.1 mm or so?– How to treat activated NaK after irradiation test?

• He-bonding concept (JP)– Whole temperature window up to 1000 deg. C. is feasible.– Cast-type capsule reduces the problem of gap.– Specimen temperature is guessed correctly by measuring d

ummy specimen temperature installed in the capsule.

EU design

Container with three compartments each with three rigs;Helium channels with a width of 1mm between the rigs

He-cooled HFTM with Chocolate-Plate-Shape Rig and Triple-Heater-Capsule

JP design -HFTM with horizontally-elongated capsules-

• Capsules are elongated in the spanwise direction to fit the beam footprint.

• Elongated capsule promote uniform temperature profile in themselves.

• Specimens are housed in cast-type capsules.

• Capsules are made of the same material as specimens to make nuclear heating in the capsules the same as specimens

• Temperature of a capsule is measured to identify that of specimens housed in it.

neutron flux

coolant flow (He)

200

50

50

[mm]

specimensT.C. <capsule inside>

Schematic of HFTM

JP design EU design

HeHe

rig

capsules

upper reflector

lateral reflector

bottom reflector

straightener

upper reflector

lateral reflector

bottom reflector

Comparison of both designitem JP EU Judge

temp. window 250 ～ 1100℃ 250 ～ 650℃ JP＞ EU

accuracy of temp. measurement of

specimens

He-bonding, measurement of temp. of dummy pieces

NaK-bonding, T.Cs inserted directly in capsule JP=EU

temp. profiledivided into 3 in vertical direction

one in vertical direction (heater capacity is challenge.)

JP＞ EU

one in horizontal direction

divided into 4 in horizontal direction

JP=EU

divided into 3 in beam direction

divided into 3 in beam direction

JP＝ EU

in case of 1-beam offheater, coolant flow rate control

heater (capacity is challenge)

JP？ EU

number of specimens

to be determined plenty JP？ EU

pressure boundary only container container and rig wall JP≧EU

remote assembly mainly threadably mounted, partly welded

welded and tightly-sealed for NaK JP≫EU

remote inspection dimensions and welded part

dimensions, welded part, NaK filling status (the biggest challenge ）

JP≫EU

Past activities @ Kyushu Univ.• Experimental tests

– Temperature control experiment for one capsule using N2 gas loop– Pressure test for a module vessel as pressure boundary– Development of porous-type manifold for flow distribution into cooling

channels• Numerical simulations

– Thermal-hydraulic calculation using k- turbulent model– Structural analysis for module vessel– Thermal-hydraulic calculation for expanded vessel using LES– Neutronics analysis in HFTM using PHITS

• Other– Fabrication of full scale dummy in order to show the fabricability for the

design of Kyushu univ. – Design of heater for temperature control

Main achievement (1)

• Temperature control in case of non-uniform nuclear heat generation was examined both experimentally and numerically.

max. 30W/cm3

center

end

neutron flux

assumed spatial distribution of nuclear heating

Test section

295.0

16.5

50.0

183.0

203.0

25.0

25.0

34.6

12.6

1.0

131.5

[mm]

[Front View] [Side View]coolant (N2)

cooling channelcapsule

insulation

Al

Photographs of test section

Test section Capsule and its supporters

1000mm

Mica heater for non-uniform heating

Ceramic heater fortemperature control

specimen for temperature measurement (Copper plate)

Mica heater for non-uniform heating

Non-heating plate

Inside view of heater for simulation of non-uniform nuclear heating

159.8

79.825.015.0

14(W/cm2) 17(W/cm2)19(W/cm2)

14.8t:1.4

0 50 100 150160

170

180

190

200

210

Thermocouple position[mm]

tem

para

ture

[℃]

Ceramic heater for temperature control

Ceramic heater for temperature control(thermal conductivity: 18[W/mK])

Non-uniform Heating heater

Non-heating plate

Photographic view of ceramic heater

Heater Heater

70 15

2.516.5

1.5

t:1.3

Custom-made heaters could not be prepared and ready-made ones were used in the present run.

location of ceramic heaters

heating region = 50mm ( 23 W/cm2)

Numerical simulation

adiabatic boundarysymmetric boundary

<Numerical conditions>Re = 939.3 (Um= 43.7 m/s) 1691 (78.9 m/s) 1880 (87.6 m/s ) 5636 ( 263 m/s)Tin = 50 deg.C, Pout = 0.3MPa

Conjugate solid/fluid heat transfer with turbulent flow

low Reynolds number k- model for flow field (Abe et al., 1993) 　　 model for temperature field (Abe et al., 1995)

2TT t

Additional heater is introduced on the end of capsule.

(SUS316)

(He)

Temperature profile in capsule -simulation-

• Temperature distributions are quite improved by heaters for temperature control.

• The use of the end heater is effective.

heater heating

Main achievement (2)

• Development of numerical codes for thermal-hydraulic, structural and neutronics analysis.– Thermal-hydraulic code using both k- model & LES– Structural analysis with thermal effect considering fini

te deformation– Neutronics analysis using PHITS

ex.) Structural analysis for HFTM vessel

• The center region of a wide wall is deflected largely due to pressure difference.

• The largest displacement appears at the corner of the vessel on the symmetry boundary side in case with thermal effect.

wall thickness=1.0 mm

deformation by pressure difference (p= 0. 3 MPa)

Mises stress

deformation by thermal effect (Re=19400)

material; F82H

Structural analysis (previous study)

200 mm

50 mm

computational domain

Max. displacement of vessel v.s. p

ex.) LES for expanded vessel

Instantaneous velocity profile at x =0 A decrease in velocity is not only the vicinity of the expanded region but all round the cross-section.

Instantaneous Temperature on capsule wall Temperature rise in case of expanded duct is remarkable in the center region.

capsule wall vessel wall

ceramic porous plate

coolant flow

bifurcation part

Porous-type manifold

testing volume

~50cm

Main achievement (3)• Development of a porous-

type manifold for flow distribution– Because of its large flow

resistance , porous media can make velocity profile uniform even in a short flow interval.

– Uniform coolant flow achieved by porous media is equally distributed at bifurcation part.

200

piesometer

anemometer200

525

53.2

40

50

straightener part

measurement partbifurcation part

capsule-array port

200 〔 mm〕

cross section of channel1mm×200mm

Test section in detail

Experimental mock-up -capsule-array port

1/1-scale of the HFTM !!

cooling channel(1mm-width)

side reflector-installation port(In this time, coolant flow through this port was not considered)

0 100 2000

2

4

6

8

10

Probe Location (mm)

Gas

Vel

ocity

(m

/s)

　 without Porous plate　 #6 ①　 #6 ①②③　 #6 ①②③④⑤

Re=3500

0 100 200

10

20

　 without Porous plate　 #6 ①　 #6 ①②③　 #6 ①②③④⑤

Probe Location (mm)

Gas

Vel

ocity

(m

/s)

Re=8000

0 100 20010

20

30　 without Porous plate　 #6 ①　 #6 ①②③　 #6 ①②③④⑤

Probe Location (mm)

Gas

Vel

ocity

(m

/s)

Re=13000

Effect of porous plates on velocity profile

For all Re, velocity profiles are remarkably improved by porous plates.

Increase in pressure drop due to increase in porous plates inserted is small. (Reduction of channel width at the bifurcation part is dominant.)

Fabrication of full scale dummy -overall view-

coolant flow

testing volume

manifold

Fabrication of full scale dummy -each part-

capsule

capsule array with top & bottom reflector

capsule array

capsule arrays in module with side

reflectors

plate heater(for temperature control)

cast-type capsule(the same material with specimens is preferred)

thermocouple

specimens

Capsule design

Can be unified?

Development of Capsule Heaters for HFTM with horizontally-elongated capsules

• Demonstration of heater-printed capsule– Thermal conductivity of conventional heater is poor,

which leads to excessive pumping power for coolant.– Unexpected occurrence of gap between heater and

capsule under operation makes temperature of capsule uncontrollable.

– The higher the heater power is, the bigger a required size of electric terminal.

Heater-printed Capsule -general view-

Side Heater(600Wx2, 40W/cm2)

End Heater(100Wx2, 40W/cm2)

20016.4

15

1.0

1.0

200 16.4

16.5

1.0

1.0

[mm]

Printed Heaters Multi-layered Ceramic Coating[mm]

• Outer mounted heaters may become thermal barrier for cooling control. (Excess pumping power)

• Small gap between heater and capsule wall should cause large non-uniformity of inner temperature distribution of capsule. (Uncontrollable situation)

• Multi-layer coating technique has been already developed in the industrial world.• Possible combination of ceramic and heater materials is Magnesia-Alumina Spine

l (MgAl2O4) and Mo.

1.0

Heat

Fl

ux Neut

ron

Flu

x

Heater-printed Capsule -cross-sectional view-

Possible partner to develop capsule heaters

• Sakaguchi E.H. VOC CORP.

model name MS-1000dimension (mm) 25×25×1.75tworking voltage 100Vcapacity(room temp.) 555±20Wpower density 89W/cm2

working temp. 1000 Max℃

withstand voltage 1500V(terminal-substrate)

substrate of heating part (Almina)2xf0.5 Ni lead-wire (polyimide tube)

model name MS-M5dimension (mm) 5×5×1.75tworking voltage 15Vcapacity(room temp.) 15Wpower density 60W/cm2

working temp. 600 Max℃

withstand voltage 1500V(terminal-substrate)

substrate of heating part (Almina)2xf0.5 Ni lead-wire (polyimide tube)