Materials for Future Fusion Reactors under Severe Stationary and Transient Thermal Loads

Transcription

1 Mitglied der Helmholtz-Gemeinschaft Materials for Future Fusion Reactors under Severe Stationary and Transient Thermal Loads J. Linke, J. Du, N. Lemahieu, Th. Loewenhoff, G. Pintsuk, B. Spilker, T. Weber, M. Wirtz Forschungszentrum Jülich, Institut für Energie- und Klimaforschung, Jülich HELSMAC Symposium - Downing College, Cambridge 7th-8th April 2016

2 Mysterious fusion

3 Mysterious fusion deuterium helium (3.5 MeV) tritium neutron (14.1 MeV)

4 Mitglied der Helmholtz-Gemeinschaft Outline: A Thermal loads on plasma facing components B Simulation of intense thermal loads C Hydrogen and helium effects D Material degradation by energetic neutrons HELSMAC Symposium - Downing College, Cambridge 7th-8th April 2016

5 A Thermal loads on plasma facing components

6 Energy conversion in a thermo-nuclear reactor

7 Steps towards the reactor JET ITER DEMO n-dose: 10-9 dpa 1 dpa 100 dpa inertially cooled wall

8 ITER and the plasma facing components first wall divertor

9 The ITER blanket design Be

10 The new ITER divertor cassette W 54 cassettes (six per vacuum vessel sector) weight approx. 9 tons / cassette W CFC # W CFC # # CFC replaced by W L max 100 mm source: M. Merola, ISFNT-9, Dalian, China, 2009

11 B Simulation of intense thermal loads on plasma-facing components

12 power density [MW/m 2 ] Expected heat loads on the ITER divertor disruptions irreversible material degradation 10 3 VDEs ELMs: 1 GW/m 2, 0.5 ms, n >> 10 6 divertor: 5-20 MW/m 2, 450 s, n ~ 10 4 off-normal normal duration of event [s] R. A. Pitts, et al., Journal of Nuclear Materials 438 (2013) S48-S56 J. Linke, Transactions of fusion science and technology 49 (2006) A. Loarte et al., Plasma Physics and Controlled Fusion 45 (2003)

13 power density [MW/m 2 ] Expected heat loads on the ITER divertor irreversible material degradation ELMs: 1 GW/m 2, 0.5 ms, n >> 10 6 divertor: 5-20 MW/m 2, 450 s, n ~ 10 4 normal duration of event [s] R. A. Pitts, et al., Journal of Nuclear Materials 438 (2013) S48-S56 J. Linke, Transactions of fusion science and technology 49 (2006) A. Loarte et al., Plasma Physics and Controlled Fusion 45 (2003)

14 surface temp. Wall loading in a toroidally confined plasma (Tokamak) mitigated transient thermal loads < 1GWm -2, Δt 500 µs pulsed stationary thermal loads < 10 MWm -2, Δt = minutes - hours 0 time thermal shock cracking/melting of PFM-surface thermal fatigue joints between PFM and heat sink

15 Loads on plasma facing components very high thermal loads plasma exposure neutrons

16 Loads on plasma facing components Steady state heat loads: up to 20 MWm -2 in ITER (lower loads in DEMO) recrystallization failure of joints very high thermal loads Transient thermal loads: up to 60 MJm -2 (disrupt., ELMs, VDEs) crackings melting dust formation plasma exposure neutrons Plasma loads: sputtering hydrogen helium Neutrons: up to 14 MeV defects transmutation

17 High heat flux test facilities Electron beam facility JUDITH 1 Electron beam facility JUDITH 2 max. power 60 kw acceleration voltage < 150 kv EB diameter ~1 mm FWHM loaded area 10 x 10 cm 2 max. power 200 kw acceleration voltage kv EB diameter 5 mm FWHM loaded area 40 x 40 cm 2

18 High heat flux test facilities Linear Plasma Device PSI-2 Electron beam facility JUDITH 2 plasma source target positions target exchange & analysis chamber linear manipulator plasma diameter 60 mm particle flux m -2 s -1 incident ion energy (bias) ev Nd:YAG laser 1064 nm laser energy 32 J max. power 200 kw acceleration voltage kv EB diameter 5 mm FWHM loaded area 40 x 40 cm 2

19 High heat flux test facilities Linear Plasma Device PSI-2 Quasi Stationary Plasma Accelerator (QSPA) plasma source target positions target exchange & analysis chamber linear manipulator plasma diameter 60 mm particle flux 1023 m-2s-1 incident ion energy (bias) ev Nd:YAG laser 1064 nm laser energy 32 J heat load MJ/m 2 pulse duration ms plasma diameter 5 cm magnetic field 0 T ion impact energy 0.1 kev electron temp. < 10 ev plasma density m -3

20 Simulation of ELMs in QSPA 20 mm

21 Bridging of gaps due to melt motion 100 E = 1.6 MJ/m 2, = 500 µs H HF = 71 MW/m 2 s 0.5 Source: A. Zhitlukhin et al., SRC RF TRINITI, Troitsk

22 Bridge formation between tungsten tiles W4,L3, 10 exposures W4,L3, 20 exposures W4,L3, 50 exposures w = 1.6 MJ/m 2 1mm 1mm 1mm H HF = 71 MW/m 2 s 0.5 W3,R3, 20 exposures W3,R3, 50 exposures W3,R3, 100 exposures w = 1.0 MJ/m 2 1mm Plasma stream direction 1mm 1mm H HF = 44.7 MW/m 2 s 0.5 t = 500 µs Source: A. Zhitlukhin et al., SRC RF TRINITI, Troitsk

23 Simulation of ELMs in QSPA H HF = 44.7 MW/m 2 s 0.5 W 3 plasma stream tungsten target E = 1.0 MJm -2 t = 500 µs 100 pulses T 0 = 500 C

24 W3 melt motion melt motion starts at vertical cracks plasma stream

25 cracking threshold Thermal shock tests on tungsten Experimental setting Sample size mm³ Loaded area 4 4 mm² Base temperature: RT up to 1000 C Power densities: 0.19 to 1.51 GW/m² transversal recrystallized longitudinal damage threshold 100 pulses with a duration of 1 ms; absorption coefficient 0.55

26 Crack Formation loaded surface cross section Plansee pure tungsten according to ITER specifications ( IGP ) L abs = 0.38 GW/m 2 (F HF = 12 MW/m 2 s 1/2 ), T base = RT transversal longitudinal recrystallized

27 ELM simulation using e-beams with high repetition rates in JUDITH 2 power density [GW/m²] damage threshold Th. Loewenhoff et al., Physica Scripta T145 (2011)

28 ELM simulation using e-beams with high repetition rates in JUDITH 2 power density [GW/m²] damage threshold Th. Loewenhoff et al., Physica Scripta T145 (2011)

29 ELM simulation using e-beams with high repetition rates in JUDITH 2 recrystallization melting 50 µm recrystallization around crack edges original grain structure Th. Loewenhoff, et al., Fusion Engineering and Design 87 (2012) µm

30 W CFC Threshold values for ELM loads damage threshold cracking of pitch fibres PSI 2010 PAN eros. >100 shots PAN erosion > 50 shots PAN erosion > 10 shots energy density* E / MJm -2 heat flux factor P Δt / MWm -2 s 1/ melting of tile edges melting of tile surface droplets bridging of tiles crack formation source: PSI 2006 / 2010 * Δt = 500 µs T 0 = 500 C CFC: NB31 W: forged rod material

31 Thermal shock testing of beryllium 5 ms Benjamin Spilker PFMC-15 Aix-en-Provence electron beam tests with 100 cycles

32 Repeated thermal shock testing of Be n = 100 n = 1000 n = mm 2 mm 2 mm power density P =1.0 MJ/m 2 pulse duration t = 5 ms P ( t) = 14 MW/m 2 s 1/2 base temperature T 0 = 250 C

33 C Hydrogen and helium effects

34 Thermal shock and He-loading Simultaneous 0.19 GWm -2 Simultaneous 0.38 GWm -2 1 µm 1 µm Only He-Plasma Simultaneous 0.76 GWm -2 1 µm 1 µm

35 Thermal shock and He-loading Simultaneous 0.19 GWm -2 Simultaneous 0.38 GWm nm 600 nm Only He-Plasma Simultaneous 0.76 GWm nm 200 nm

36 D Materials degradation by energetic neutrons

37 Neutron-induced material degradation High Flux Reactor (HFR) Petten, The Netherlands Neutron induced effects: activation of plasma facing and structural materials e.g. Co, Ag transmutation due to 14 MeV neutrons W Re Os Be He, T degradation of thermal and mechanical properties thermal conductivity, hardening, embrittlement

38 thermal conductivity (W m -1 K -1 ) thermal conductivity / W/m thermal th. conductivity conductivity / W/mK (W m -1 K -1 ) n-irradiation effect on thermal conductivity un-irradiated 0.2 dpa 1 dpa CFC (NB31) temperature temperature / C ( C) tungsten un-irradiated 0.1 dpa 0.6 dpa 150 Laser-flash-apparatus (schematic) temperature / C temperature ( C)

39 t e m p e r a t u r e / C HHF performance of neutron irradiated divertor modules Dunlop Concept 1 (12 mm) / CuCrZr IR - 551_11~1.IMG 2100,0 C T irr = 350 C / 0.3 dpa 2000 b e s t r a h l t u n b e s t r a h l t :09:97 09:59: , IR - DZ150SS.IMD 2100,0 C t h e r m a l l o a d / M W m ,0 Zykliertests an CFC-Modulen vom Type N

40 Future fusion materials research in HML very high thermal loads hot cell JUDITH 1 1 plasma exposure neutrons JULE-PSI hot cell 1