Design activity of high flux test module of ifmif in kyushu univ
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Design Activity of High Flux Test Module of IFMIF in Kyushu Univ. A. [email protected] Univ. Outline of IFMIF. Accelerator facilities. Target facilities. Test facilities. Supply 500cm 3 irradiation volume with 10 14 n/s ・ cm 2 (20dpa per year) neutron flux

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

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Design activity of high flux test module of ifmif in kyushu univ

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

A. [email protected] Univ.


Outline of ifmif

Outline of IFMIF

Accelerator facilities

Target facilities

Test facilities

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

  • Irradiation temperature: 250~1000℃

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

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

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

Li flow

Deuteron beams

Test piece

Neutron irradiation

Injector

RFQ

DTL

Test Cell

Heat exchanger

PIE facilities

Magnet pump

  • Engineering design over the whole system of IFMIF

Design & Integration

Mission

  • 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.


Test cell configuration

Test Cell Configuration

shielding plug

for high flux region

for low & very low

flux regions

for medium flux region

2.5m

D

+

Lithium target

Li quench tank


Required performance for temperature control in he cooled high flux test module

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%.

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

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

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


Original design of test module

Original design of test module

Rig

Test

Pieces

Capsule

Gap

T.C.


Large uncertainty of temperature measurement

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

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.

  • Effective gap conductance lgap 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.

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.

Estimation of uncertainty of

temperature measurement


Change in design derivation of hftm

Change in design & derivation of HFTM

  • Ultimate purpose of HFTM

    Temperature control for irradiated specimens for long 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 and guessed temperature in specimens arises easily.

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


Features of both design

Features of both design

  • NaK-bonding concept (EU)

    • Problem originated from gap condition is overcome due to high 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 dummy specimen temperature installed in the capsule.


Eu design

EU design

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

Container with three compartments each with three rigs;

Helium channels with a width of 1mm between the rigs


Jp design hftm with horizontally elongated capsules

T.C.

specimens

<capsule inside>

JP design -HFTM with horizontally-elongated capsules-

coolant flow (He)

  • 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.

[mm]

200

50

neutron flux

50


Schematic of hftm

Schematic of HFTM

upper reflector

He

He

rig

upper reflector

lateral reflector

capsules

lateral reflector

bottom reflector

bottom reflector

straightener

JP design

EU design


Comparison of both design

Comparison of both design


Past activities @ kyushu univ

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-e 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

max. 30W/cm3

end

neutron flux

center

Main achievement (1)

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

assumed spatial distribution of nuclear heating


Test section

203.0

34.6

183.0

50.0

25.0

131.5

16.5

25.0

cooling

channel

295.0

12.6

1.0

[mm]

coolant (N2)

[Side View]

[Front View]

Test section

insulation

capsule

Al


Photographs of test section

Photographs of test section

1000mm

Test section

Capsule and its supporters


Mica heater for non uniform heating

159.8

t:1.4

79.8

14.8

25.0

15.0

17(W/cm2)

14(W/cm2)

19(W/cm2)

Mica heater for non-uniform heating

Ceramic heater for

temperature control

specimen for temperature measurement (Copper plate)

Mica heater for non-uniform heating

Inside view of heater for simulation

of non-uniform nuclear heating

Non-heating plate


Ceramic heater for temperature control

70

15

t:1.3

Heater

Heater

16.5

2.5

1.5

Ceramic heater for temperature control

Ceramic heater for temperature control

(thermal conductivity: 18[W/mK])

location of ceramic heaters

Non-uniform

Heating heater

Photographic view of ceramic heater

Non-heating plate

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

heating region = 50mm ( 23 W/cm2)


Numerical simulation

Numerical simulation

Conjugate solid/fluid heat transfer with turbulent flow

(He)

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

model for temperature field (Abe et al., 1995)

Additional heater is introduced on the end of capsule.

<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

(SUS316)

adiabatic boundary

symmetric boundary


Temperature profile in capsule simulation

Temperature distributions are quite improved by heaters for temperature control.

The use of the end heater is effective.

Temperature profile in capsule -simulation-

heater heating


Main achievement 2

Main achievement (2)

  • Development of numerical codes for thermal-hydraulic, structural and neutronics analysis.

    • Thermal-hydraulic code using both k-e model & LES

    • Structural analysis with thermal effect considering finite deformation

    • Neutronics analysis using PHITS


Ex structural analysis for hftm vessel

ex.) Structural analysis for HFTM vessel

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

wall thickness=1.0 mm

  • 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.

deformation by thermal effect (Re=19400)

Mises stress


Structural analysis previous study

Structural analysis (previous study)

200 mm

50 mm

computational domain

Max. displacement of vessel v.s.Dp

material; F82H


Ex les for expanded vessel

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.

capsule wall

vessel wall

Instantaneous Temperature on capsule wall

 Temperature rise in case of expanded duct is remarkable in the center region.


Main achievement 3

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.

coolant flow

Porous-type manifold

testing volume

~50cm

bifurcation part

ceramic porous plate


Test section in detail

Test section in detail

anemometer

capsule-array port

200

cross section of channel

1mm×200mm

bifurcation part

40

measurement part

50

piesometer

525

straightener part

200

53.2

〔mm〕

200


Experimental mock up capsule array port

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)


Effect of porous plates on velocity profile

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

Fabrication of full scale dummy -overall view-

coolant flow

testing volume

manifold


Fabrication of full scale dummy each part

Fabrication of full scale dummy -each part-

 capsule

capsule array 

  • capsule array with

    top & bottom reflector

capsule arrays in 

module with side

reflectors


Capsule design

Capsule design

specimens

thermocouple

cast-type capsule

(the same material with specimens is preferred)

Can be unified?

plate heater

(for temperature control)


Development of capsule heaters for hftm with horizontally elongated capsules

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

1.0

1.0

15

200

16.4

Heater-printed Capsule -general view-

Side Heater

(600Wx2, 40W/cm2)

End Heater

(100Wx2, 40W/cm2)

1.0

1.0

16.5

[mm]

200

16.4


Heater printed capsule cross sectional view

Heater-printed Capsule -cross-sectional view-

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 Spinel (MgAl2O4) and Mo.

1.0

Neutron

Flux

Heat Flux


Possible partner to develop capsule heaters

dimension (mm)

dimension (mm)

5×5×1.75t

25×25×1.75t

working voltage

working voltage

15V

100V

capacity(room temp.)

capacity(room temp.)

15W

555±20W

power density

power density

89W/cm2

60W/cm2

working temp.

working temp.

1000℃Max

600℃Max

withstand voltage

withstand voltage

1500V(terminal-substrate)

1500V(terminal-substrate)

Possible partner to develop capsule heaters

  • Sakaguchi E.H. VOC CORP.

substrate of heating part (Almina)

substrate of heating part (Almina)

2xf0.5 Ni lead-wire (polyimide tube)

2xf0.5 Ni lead-wire (polyimide tube)

model name

MS-1000

model name

MS-M5


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