Upload
lamnguyet
View
217
Download
1
Embed Size (px)
Citation preview
Critical issues & challenges in the engineering of DEMO divertor target
J.-H. You, E. Visca, Ch. Bachmann, &EUROfusion Divertor Project Team
J.-H. YOU et al. | IAEA Divertor Workshop | 29 Sep. – 2 Oct. 2015 |
armor
heat sink Plansee
Plasma‐facing unit (ITER)
Vertical target (ITER)
DEMO divertor in EUROfusion
Technical boundary conditions (DEMO)
Power to exhaust: 259 MW in total Power deposited in PFU: 112 MWParticle flux: ~1024/m²∙sHeat flux stationary: max. 10MW/m² transient: max. 20 MW/m² neutron irradiationW: 3 dpa/fpy, Cu: 6‐10 dpa?/fpyNumber of pulsesstationary: 5000 cycles?transient: 300 cycles?Replacement period: 2 fpy
Missions
assure the envisaged power exhaust goal for DEMO deliver holistic design concept for the DEMO divertor develop feasible technology for high performance target (NB. irradiation)
Approaches water‐cooling for the early DEMO, helium‐cooling as long‐term option reliable cooling capability as paramount requirement (also for slow transient) advanced novel Target design concepts vs. baseline model (ITER‐like) design study as well as technology development incl. HHF tests dedicated (structural) design rules tailored for the joined PFCs
EUROfusion work package ‘Divertor’
0
10
20
30
40
50
60
10 12 14 16 18 20
Critical heat flux (M
W/m
²)
Water velocity (m/s)
Pressure: 5 MPaTube diameter: 12 mmSwirl (Tong‐75)
150 °C160 °C180 °C200 °C220 °C
‐max. surface heat flux: 20 MW/m² ‐ heat flux peaking factor: ~1.6‐ envisaged margin to the CHF: ~1.5‐ local critical heat flux: ~48 MW/m²
‐ tube diameter: 12 mm‐ pressure: 5 MPa
‐ temperature: 150 °C ‐ velocity: 16 m/s
Design rationale: cooling condition
Estimated cooling capability of Target
You, Fus. Eng. Des (submitted)
Target heat sink: performance of irradiated CuCrZr alloy
local fracture due to exhausted ductility Sd
plastic flow localisation Seratchetting 3Sm
Design stress limits over temperature
Allowable operation temp. rangeaccording to elastic design rules:250 °C – 300 °C
Impracticable for DEMO divertor
ITER SDC‐IC Annex AYou, Nucl. Fusion (2015)
Target heat sink: performance of CuCrZr tube
10 MW/m² 15 MW/m² 18 MW/m²Max. temp. at top 263 °C 316 °C 348 °CMid‐temp. at side 172 °C 181 °C 187 °CMin. temp. at bottom 150 °C 150 °C 150 °C
Predicted temperature profiles in the cooling tube (coolant: 150 °C)
Critical material issues for the heat sinkirradiation creep
high‐temperature strength
neutron embrittlement toughness /non‐ductile structural design
°Cmax
mid
You, Nucl. Fusion (2015)
Target heat sink: design with novel design rules
Structural design scheme
T>250°C: recovery of embrittlement Se, Sd criteria: no issue 3Sm criterion: only for elastic design plastic design rules (LCF, creep‐fatigue)
T<200°C: negligible uniform elongation Se criterion not satisfied
T>150°C: total elongation exploitable (strain‐controlled loading!)
employ a non‐ductile design rulefor 150 °C < T < 250 °C
Tensile test curves of CuCrZr
You, Nucl. Fusion (2015)You, Nucl. Mater. Energy (2015)Fenici, et al., J. Nucl. Mater. (1994)
Target heat sink: design with novel materials
Wf-Cu composite tube
200 mm
v. Müller, You (IPP)You, Nucl. Mater. Energy (2015)
W wire-reinforced Cu composite
CuCrZr
Wp/Cu
W
Wp/Cu composite block with a W armor tile (5 mm thick)
You, Brendel et al., J. Nucl. Mater. (2013)
Particulate W-Cu composite
Target heat sink: design with novel materials
Wp-Cu composite mock-up
22×24×150 mm³
v. Müller, You (IPP)
W/Cu laminate
Target heat sink: design with novel materials
W laminate pipe (1000 mm)
W/V laminate
Reiser, Rieth (KIT)
Water‐cooled mock‐up (W/Cu)
Helium‐cooled mock‐up (W/V)
Highly porous Cu felt layer‐ thermal conductivity: ~15 W/mK‐ elastic modulus: <1GPa
Target heat sink: design with novel materials
Barrett et al. (CCFE)
Chromium block/ tungsten armour
v. Müller, You (IPP)
Target heat sink: design with novel materials
Chromium block HHF test mock‐up Temperature range at center line(10MW/m2, Cr: 2mm, 200 °C)3mm W: 725 ‐ 1172 °C (> DBTT)2mm Cr: 345‐ 725 °C Tube CuCrZr: 200 ‐ 323 °C
LCF lifetime (Cu interlayer)> 5000 cycles at 10 MW/m²
for 400 °C < T < 800 °CCTE: 9 ‐ 10×10‐6/KE: 280 ‐ 255 GPa: 76 ‐ 63 W/mKDBTT: 250 ‐ 300 °CRp0.2: 165 ‐ 140 Mpa
Low activation target concept
Stamm, JNM (1998)
Target concepts Coolant Armor Interlayer Heat sink Design logics
ITER‐like(ENEA)
water W Cu CuCrZr Baseline design. To be evaluated for DEMO
Thermal break(CCFE)
water W Porous Cu felt
CuCrZr Reduce heat flux concentration & stiffness
Composite(IPP)
water W Wwire/Cu composite
Enhance high‐temp.strength & toughness
Chromium(IPP)
water W Cu Cr blockCuCrZr tube
Lower DBTT &low activation (Dome)
Functionally graded (CEA)
water W W/Cu FGM CuCrZr Enhance joining quality
W laminate 1(KIT)
water W Cu W/Cu laminate
Enhance high‐temp.strength & toughness
W laminate 2(KIT)
helium W Cu? W/V laminate
Enhance high‐temp strength & toughness
Target: design concepts under development
Details on the subproject ‘Target’ will be presented at ICFRM‐17
W/Cu laminate
Functionally graded
Wf/Cu composite(200 mm long tube)
Target: advanced design concepts (water-cooled)
Cr block (high dpa region)
Wp/Cu composite(low HHF region)
Thermal break
ITER‐like
He-cooled target in WPDIV
classified as long‐term option: basic R&D for FPPan alternative design concept based on W/Cu laminate tube
→ DBTT within the allowed temperature range of irradiated Eurofer(ODS)?
Target: advanced design concept (helium-cooled)
Summary
Water‐cooling as near‐term design option (He‐cooling: long‐term)
Cu‐base materials for Target heat sink, Eurofer steel for Cassette body
150 °C as local inlet temperature at strike point
Envisaged goal of max. heat flux density to exhaust: 20 MW/m²
Critical material issues identified for heat sink & armour
Advanced novel design concepts + baseline model
Non‐ductile structural design rules (toughness/plastic strain)
Technology development (materials, joining, etc.)
1st phase mock‐up fabrication in 2015, HHF test campaigns in 2016
Pintsuk, Fus. Eng. Des. (2013)
20 MW/m² (4 mm) 15 MW/m² (2 mm)
LCF life at W surface 86 cycles 617 cycles
ITER divertor targetHHF fatigue test20 MW/m²300 load cycles
Li, You, Fus. Eng. Des. (2015)
Target: tungsten armour cracking
Temperature (20 MW/m²) Thermal stress (HHF/cooling) Plastic strain (5th cycle)
Recrystallized(4 mm)
During coolingDuring HHF loading
J-integral at different crack lengths
Crack: 1.5 mm
Crack: 3.5 mm
Crack: 5.5 mm
Crack: 1.5 mm
Crack: 3.5 mm
Crack: 5.5 mm
During HHF loading
During cooling
Stress fields at different crack lengths
Li, You, Fus. Eng. Des. (2015)
Target: tungsten armour cracking
Li, You, Fus. Eng. Des. (2015)
Target: tungsten armour cracking
During cooling During cooling
15 MW/m² 18 MW/m²Li, You, Fus. Eng. Des. (2015)
Target: tungsten armour cracking
ErOx
ErOx/W
ZrOx
ZrOx/W
Du, You, Composite Sci. Tech. (2010)
In-situ synchrotron tomography
Riesch, You, Acta Mater. (2013)
Bending test (single-fiber composite)Microstructure
Target: W wire-reinforced W composite for armour
Work package ‘Divertor’: work breakdown structure
Melting point<500°C Radioactivity/TritiumAvailability/Cost Strength at 300°CDuctility at 200°C Water corrosion
Solid elements at RT with thermal conductivity > 50 W/mK
Target heat sink: material requirements
TaX
You, Nucl. Fusion (2015)
Cassette: revised model (2015)
Baffle: attached to the breeding blanketStrongly reduced size (54 Cassettes)
Gain in tritium breeding ratio: 1.13 1.19Nuclear heating power: 147 MW