Design Activity of High Flux Test Module of IFMIF in Kyushu Univ. A. 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 500cm 3 irradiation volume with n/s ･ cm 2 (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. Mission Outline of IFMIF

Test Cell Configuration Lithium target D+ shielding plug for medium flux region for high flux region for 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 ( ℃ ) 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 Pieces Capsule Gap 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. Estimation of uncertainty of temperature 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. 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 HFTM  Temperature control for irradiated specimens for long time periods in temperature window of 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 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 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) [mm] specimensT.C.

Schematic of HFTM JP designEU design He rig capsules upper reflector lateral reflector bottom reflector straightener upper reflector lateral reflector bottom reflector

Comparison of both design itemJPEUJudge 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. profile divided 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 JP ＝ EU in case of 1-beam off heater, coolant flow rate control heater (capacity is challenge) JP ？ EU number of specimensto be determinedplenty JP ？ EU pressure boundaryonly containercontainer 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 Kyushu Univ. Experimental tests –Temperature control experiment for one capsule using N 2 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/cm 3 center end neutron flux assumed spatial distribution of nuclear heating

Test section [mm] [Front View] [Side View] coolant (N 2 ) cooling channel capsule insulation Al

Photographs of test section Test section Capsule and its supporters 1000mm

Mica heater for non-uniform heating Ceramic heater for temperature 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 (W/cm 2 ) 17(W/cm 2 ) 19(W/cm 2 ) 14.8 t:1.4

Ceramic heater for temperature control (thermal conductivity: 18[W/mK]) Non-uniform Heating heater Non-heating plate Photographic view of ceramic heater Heater 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/cm 2 )

Numerical simulation adiabatic boundary symmetric boundary Re = (U m = 43.7 m/s) 1691 (78.9 m/s) 1880 (87.6 m/s ) 5636 ( 263 m/s) T in = 50 deg.C, P out = 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) 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 finite 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 wallvessel 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 anemometer straightener part measurement part bifurcation part capsule-array port 200 〔 mm 〕 cross section of channel 1mm×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)

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/cm 2 ) End Heater (100Wx2, 40W/cm 2 ) [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 Spinel (MgAl 2 O 4 ) and Mo. 1.0 Heat Flux Neutron Flux Heater-printed Capsule -cross-sectional view-

Possible partner to develop capsule heaters Sakaguchi E.H. VOC CORP. model nameMS-1000 dimension (mm)25×25×1.75t working voltage100V capacity(room temp.)555±20W power density89W/cm 2 working temp ℃ Max withstand voltage1500V(terminal-substrate) substrate of heating part (Almina) 2xf0.5 Ni lead-wire (polyimide tube) model nameMS-M5 dimension (mm)5×5×1.75t working voltage15V capacity(room temp.)15W power density60W/cm 2 working temp. 600 ℃ Max withstand voltage1500V(terminal-substrate) substrate of heating part (Almina) 2xf0.5 Ni lead-wire (polyimide tube)