Max-Planck-Institut für Plasmaphysik Boundary Conditions for a Solid State Divertor in a Fusion Power Plant Rudolf Neu Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany 1 st IAEA Technical Meeting on Divertor Concepts, Vienna, 29 Sep. – 2 Oct. 2015
G.F. Federici ‘ Design approach and prioritization of R&D activities towards an EU DEMO’, ISFNT 2015 Outstanding Technical Challenges with Gaps beyond ITER For any further fusion step, safety, T-breeding, power exhaust, RH, component lifetime and plant availability, are important design drivers and CANNOT be compromised Tritium breeding blanket Power Exhaust - most novel part of DEMO - Peak heat fluxes near - TBR >1 marginally technological limits achievable but with (>10 MW/m 2 ) thin PFCs/few penetrations - ITER solution may be marginal - Feasibility concerns/ for DEMO performance uncertainties Advanced divertor solutions - with all concepts -> R&D may be needed but integration - Selection now is premature is very challenging - ITER TBM is important Structural and HHF Materials Remote Maintenance - Progressive blanket operation strategy (1 st blanket 20 dpa; 2 nd blanket 50 dpa) - Strong impact on IVC design - Embrittlement of RAFM steels and Cu-alloys at - Significant differences with ITER low temp. and loss of mechanical strength at ~ RM approach for blanket high temp. - RH schemes affects plant design - Need of structural design criteria and design and layout codes - Large size Hot Cell required - Technical down selection and development of an - Service Joining Technology Early Neutron Source (IFMIF-DONES) R&D is urgently needed. G. Federici & PPPT Team | ISFNT-12 |Jeju Island (Korea)| 14/09/2015| Page 2
G.F. Federici ‘ Design approach and prioritization of R&D activities towards an EU DEMO’, ISFNT 2015 Outstanding Technical Challenges with Gaps beyond ITER For any further fusion step, safety, T-breeding, power exhaust, RH, component lifetime and plant availability, are important design drivers and CANNOT be compromised Tritium breeding blanket Power Exhaust - most novel part of DEMO - Peak heat fluxes near - TBR >1 marginally technological limits achievable but with (>10 MW/m 2 ) thin PFCs/few penetrations - ITER solution may be marginal - Feasibility concerns/ for DEMO performance uncertainties Advanced divertor solutions - with all concepts -> R&D may be needed but integration - Selection now is premature is very challenging - ITER TBM is important Structural and HHF Materials Remote Maintenance - Progressive blanket operation strategy (1 st blanket 20 dpa; 2 nd blanket 50 dpa) - Strong impact on IVC design - Embrittlement of RAFM steels and Cu-alloys at - Significant differences with ITER low temp. and loss of mechanical strength at ~ RM approach for blanket high temp. - RH schemes affects plant design - Need of structural design criteria and design and layout codes - Large size Hot Cell required - Technical down selection and development of an - Service Joining Technology Early Neutron Source (IFMIF-DONES) R&D is urgently needed. G. Federici & PPPT Team | ISFNT-12 |Jeju Island (Korea)| 14/09/2015| Page 3
G.F. Federici ‘Design approach and prioritization of R&D activities towards an EU DEMO’, ISFNT 2015 DEMO Physics Basis / Operating Point • Readiness of underlying physics assumptions makes the difference. • The systems code PROCESS is being used to underpin EU DEMO design studies, and another code (SYCOMORE), is under development. G. Federici & PPPT Team | ISFNT-12 |Jeju Island (Korea)| 14/09/2015| Page 4
G.F. Federici ‘Design approach and prioritization of R&D activities towards an EU DEMO’, ISFNT 2015 Divertor and H-mode Operation as “size - drivers“ • One crucial point is the size of the device and the amount of power that can be reliably produced and controlled in it. • This is the subject of research and depends upon the assumptions that are made on the readiness of required advances in physics, technology and materials developments. • Main objectives: *Protect divertor P sep =P α +P add -P rad,core Physics/ Material limits P sep /R ≤17MW/m *H-mode operation (P LH R): f LH= P sep /P LH,scal → confinement quality and controllability P sep ≥ P LH R. Kemp (CCFE) - PROCESS Fix P el,net =500 MW pulse = 2 h - Scan Z eff G. Federici & PPPT Team | ISFNT-12 |Jeju Island (Korea)| 14/09/2015| Page 5
G.F. Federici ‘Design approach and prioritization of R&D activities towards an EU DEMO’, ISFNT 2015 Preliminary DEMO Design Choices under Evaluation Design features (near-term DEMO): DEMO1 DEMO2 • 2000 MW th ~500 Mw e • Pulses > 2 hrs • SN water cooled divertor • PFC armour: W • LTSC magnets Nb 3 Sn (grading) • B max conductor ~12 T (depends on A) Under • RAFM (EUROFER) as blanket structure revision • VV made of AISI 316 • Blanket vertical RH / divertor cassettes • Lifetime: starter blanket: 20 dpa (200 appm He); 2 nd blanket 50 dpa; ITER DEMO1 DEMO2 divertor: 5 dpa (Cu) (2015) A=3.1 (2015) A=2.6 R 0 / a (m) 6.2 / 2.0 9.1 / 2.9 7.5 / 2.9 Κ 95 / δ 95 1.7 / 0.33 1.6 / 0.33 1.8 / 0.33 Open Choices: A (m 2 )/ Vol (m 3 ) 683 / 831 1428 / 2502 1253 / 2217 • Operating scenario H non-rad-corr / β N (%) 1.0 / 2.0 1.0 / 2.6 1.2 / 3.8 • Breeding blanket design concept selection P sep (MW) 104 154 150 • Primary Blanket Coolant/ BoP P F (MW) / P NET (MW) 500 / 0 2037 / 500 3255 / 953 • Protection strategy first wall (e.g., limiters) I p (MA) / f bs 15 / 0.24 20 / 0.35 22 / 0.61 B at R 0 (T) 5.3 5.7 5.6 • Advanced divertor configurations B max , conductor (T) 11.8 12.3 15.6 • Number of coils BB i/b / o/b (m) 0.45 / 0.45 1.1 / 2.1 1.0 / 1.9 Av NWL MW/m 2 0.5 1.1 1.9 O-6 : F. Maviglia G. Federici & PPPT Team | ISFNT-12 |Jeju Island (Korea)| 14/09/2015| Page 6
Boundary Conditions for Divertor Plasma Facing Components • Plasma Compatibility: R-2: A. Leonard R-6: M. Wischmeier radiation, dilution, stability, … R-8: W. Morris I-3: B. Lipschultz • Tritium Compatibility: I-10: J.W. Coenen retention, co- deposition, penetration, … • Erosion Behaviour: I-10: J.W. Coenen I-5: S. Hong lifetime, dust production, … P4: S. Khirwadkar P5: Th. Loewenhoff • ‚Corrosion‘ Issues: reactions with seeding impurities, air, water, … I-10: J.W. Coenen • Thermo-Mechanical Behaviour: I-11: Rieth I-10: Coenen I-6: Firdaouss thermal conductivity, strength, DBTT, … O-6: Riesch O-11: You P-8: Nikolic • Joining Issues: I-11: M. Rieth O-11: J.-H.You joining to / compatibility with heat sink materials, … • Behaviour Under n-Irradiation: I-11: M. Rieth I-10: J.W. Coenen activation, transmutation, change of thermo- mechanical properties, … • Industrial production routes: availability, scalability, reliability of processes, … O-10: N. Wang / G. Luo 1 st IAEA TM on Divertor Concepts, Vienna, 29 Sep. – 2 Oct. 2015 Rudolf Neu 7
Basic Plasma - Wall Interaction Processes PWI & PFM determine • component lifetime Reflection • T retention • dust production • plasma compatibility Re-deposition Erosion T co deposition Plasma Facing Material 1 st IAEA TM on Divertor Concepts, Vienna, 29 Sep. – 2 Oct. 2015 Rudolf Neu 8
P/R as a figure of merit Device P heat /R upstream q || unmitig. q ( int = 2.6 mm) * (MW/m 2 ) (GW/m 2 ) (MW/m) JET 7-12 2 8 AUG 14 3.5 13 ITER 20 5 20 30 DEMO 80-100 115 *based on the scaling of upstream SOL width (no size scaling and no radiation losses) by T. Eich et al. PRL 2011, see also A. Scarabosio JNM 2013 strong mitigation (> factor 7) of heat flux necessary radiative cooling (bulk, SOL & divertor) M. Wischmeier , JNM 2015 1 st IAEA TM on Divertor Concepts, Vienna, 29 Sep. – 2 Oct. 2015 Rudolf Neu 9
Steady state and transient thermal loads (in ITER) permanent degradation of material power density / MWm -2 Disruptions frequencies disruptions fast current quench for different n 200 events in ITER VDEs VDEs 10 3 Vertical Displacement ELMs n 1000 Events n 10 6 (loss of position control) divertor n 10 ELMs: ´steady state´ 1 transients Edge Localized Modes (periodical ejection of first wall particles and energy in high confinement (H)-Mode) 10 -3 1 10 3 ( all transients need mitigation!) duration / s after J. Linke Phys. Scripta 2006 1 st IAEA TM on Divertor Concepts, Vienna, 29 Sep. – 2 Oct. 2015 Rudolf Neu 10
Operational domain of high power H-mode in AUG R=6.2 m A. Kallenbach R=1.65 m et al., NF 2015 P sep /R is divertor identity parameter, provided similar density and power width applying the ITER divertor solution to DEMO, high f rad is needed! 1 st IAEA TM on Divertor Concepts, Vienna, 29 Sep. – 2 Oct. 2015 Rudolf Neu 11
Bulk radiation will strongly narrow operational range 0-D Calculations for Ignition He Concentrations are typically 10-20% (for He / E =5) T. Pütterich, EFPW Split 2014 1 st IAEA TM on Divertor Concepts, Vienna, 29 Sep. – 2 Oct. 2015 Rudolf Neu 12
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