Fusion Energy Achievements and Challenges

1. Fusion Energy Achievements and Challenges Gianfranco Federici Head of EFDA PPPT Department March 26, 2012 Deutsche Physikalische Gesellschaft e.V. Berlin, Germany

2. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

3. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

4. Incentives for Developing Fusion Fusion energy can also be used to H, and for desalination Pros • Abundant fuel (D + Li) • No greenhouse gases • Safe – no chain reaction, ~1 sec worth of fuel in device at any one time • Minimal “afterheat”, no nuclear meltdown • Residual radioactivity small; products immobile and short-lived • Minimal proliferation risks • No seasonal, diurnal or regional variation Cons • We don’t know how to do it yet (it is a really hard problem) • Capital costs will be high, unit size large

5. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

6. The Next Frontier ITER D + T → n + α+ 17.58 MeV Understanding the behavior of burning plasmas is a necessary step towards the demonstration of fusion as a source of energy. Q=10 • ITER, to be built and operated as an international project, will push research efforts into this new regime of burning plasma science “Burning” plasma = dominantly self-heated by fusion products (e.g., alpha particles) from thermonuclear reactions in the plasma.

7. 2011 September 2011 December 2011 Polidal Field Coil Building (257m x 49m x 18m h)

8. February 2012 Complete deployment of sismic pads More fotos and video on: //www.iter.org/org/team/odg/comm

9. JET and ASDEX-Up Mitigation of ITER operation risks • Top Risks • Disruption mitigation has limited effectiveness • H-mode power threshold at high end of uncertainty range • ELM mitigation schemes has limited effectiveness • Vertical stability control limited by excessive noise (or failure of in-vessel coils) • Lack of reliable high power heating during non-active phase of programme • Acceptable “divertor” performance with W. • High levels of T retention require more frequent T removal procedures than foreseen • Incompatibility of core plasma requirements for Q=10 with radiativedivertor operation • Inability to achieve densities near Greenwald value required for Q=10 Source: Lorne Horton (EFDA-Culham)

10. JT-60SAExplore advanced modes of operation JT-60SA(A≥2.5,Ip=5.5 MA) ITER (A=3.1,15 MA) 3.0m 6.2m 1.1m SST-1 (A=5.5, 0.22 MA) 1.7m EAST (A=4.25,1 MA) 1.8m KSTAR (A=3.6, 2 MA) • JT60-U: Copper Coils (1600 T), Ip=4MA, Vp=80m3 • JT60-SA: SC Coils (400 T), Ip=5.5MA, Vp=135m3 JT-60SA JT-60U Source: P. Barabaschi, F4E ~4m ~2.5m 10

11. Wendelstein 7-X W7-X: Major Milestones W7-X: Assembly according to plan • Completion: • Steady state divertor • Increase in heating power, ICRH • Diagnostic completion • During first campaign: • 8MW ECRH and 7 MW NBI • Diagnostics set probably sufficient to conduct the initial program • Test divertor unit to study operation limits and divertor physics No delays expected: finished mid 2014

12. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

13. Roadmap(s) to Fusion Energy • Different countries face different energy needs and these drive different strategies for fusion development. • The greater the perceived urgency for fusion energy the greater the willingness to take larger steps and larger risks. • All ITER parties have a target to demonstrate fusion-driven electricity production by ~2050. • The roadmaps of Chinaand India, that foresee the largest increase in energy demand in the next decades, are the most ambitious, in terms of both goals and timescale for next steps. • China is considering the construction of a further DT machine. Engineering Design Phase is expected in 2014 and first plasma in 2025. In Eu the Roadmap is being revisited. The plan is to launch a vigorous coordinated effort to prepare for a fusion Demonstration Reactor to be built by the beginning of 2030 (EFDA PPPT Dept. is the very first step in this direction).

14. Define Next-Step (after ITER) • Today, there is still a divergence of opinions on how to bridge the gap between ITER and the first FPP. • EU (and JA): DEMO and IFMIF; • US: CTF or a Pilot Plant and no dedicated materials test facility. R. Goldston (IAEA TM, June 2011) • However, there are some common outstanding issues common to any next major facility after ITER, whether a CTF, a Pilot Plant, a DEMO, or else: • Power exhaust handling (divertor) • Reference plasma scenario  CD requirements, • Coolant for in-vessel components  breeding blanket concept • Maintenance scheme  plant architecture • Structural and PFC materials • Only some of these issues can be solved in ITER.

15. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

16. DEMO Technical Challengeswith potentially large gaps beyond ITER ITER objectives and design are well established; - not yet the case for DEMO. • PHYSICS • Operating scenario: Long pulse/ Steady-state/ High-Beta • High density operation • Power exhaust and divertor R&D strategy • Abnormal events avoidance/ mitigation • Plasma diagnostics and control • TECHNOLOGY • PFC and Blanket technology including T self-sufficiency • H&CD Systems – Efficiency and Reliability • Reliability of Core Components & RH for high machine availability • Qualification of resilient structural materials • Safety and licensing

17. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

18. Power Exhaust and Divertors Very High Heat Fluxes • Power density fusion reactors much smaller than fission reactors • But peak-to-average heat flux at coolant surfaces much higher Source table: Abdou (UCLA)

19. DivertorTechhnology Water-cooling ITER Technology, W and Cu-Cr-Zr He-cooling ITER Technology, W and Cu-Cr-Zr • 20 MW/m2 possible 15 MW/m2 reliable add neutrons < 10 MW/m2 • 12 MW/m2 possible 10 MW/m2 reliable add neutrons ~5 MW/m2 • 2000 cycles at 15 MW/m2 on W. • More recently 300 cycles at 20 MW/m2 (ITER requirements) + 500 pulses at 0.5 MJ/m2 to simulate ELM-like loads • Longitudinal macro-cracks appeared in all monoblocks. • some melting of W at monoblock edges • But no degradation of their power handling capability Norajitra, KIT -Helium-cooled modular divertor (HEMJ) • >1000 cycles at 10 MW/m2. • Recently cycles at 12 MW/m2 • Thimble is still the most critical component. • Influence of irradiation is unknown • Design integration and reliability still to be addressed Source: Riccardi (F4E), Visca (ENEA) Source: Norajitra (KIT)

20. Advanced Divertorsmagnetic shaping “Snowflake divertor” has been studied and achieved in TCV and more recently NSTX Issue – in-vessel coil shielding • created by using only 2-3 existing magnetic coils. • the peak heat load is reduced, because it flares the SOL at the divertor surface. • Limited impact expected on the high performance and confinement. • ‘Super-X’ is one concept where magnetic geometry could handle extremely high divertor loads • • SOL taken to large major radius • natural flux expansion; • • SOL passes through low PF region • connection length is increased • further spread of power – • volume to enable power radiation before striking target. V. Soukhanovskii (LLNL)

21. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

22. Tritium Supply and Breeding We focus on the D-T cycle (easiest): • D + T → n + α+ 17.58 MeV Tritium does not exist in nature! • Decay half-life is 12.3 years • T must be generated inside the blanket Large consumption of tritium during fusion • 55.8 kg/yr per 1000 MW of fusion power Production and cost • CANDU reactors: 27 kg over 40 years, $30M/kg currently • Other fission reactors: 2-3 kg/yr $84-130M/kg The only possibility to breed tritium is through neutron interactions with Li that must be used in some forms • Tritium breeding for self-sufficiency • World supply of tritium is sufficient for 20 years of ITER operation (will need ~17.5 kg, leaving ~5 kg) • Verified tritium breeding technology, to be tested on ITER, will be required for DEMO and reactors.

23. Breeding Blankets Source L. Boccaccini (KIT) Principles of HCPB blanket concept: breeding and T extraction (shown as example) During ITER Research Programme, TBMs will be installed in ITER to investigate breeding. ITER has three ports for blanket testing and 2 TBMs can be installed in each port. Helium at 300-500°C @ 8MPa HCPB HCLL Li cer. Be. CPS: Coolant Purification Sys. TES: Tritium Extraction System There are other alternative Blanket Design Concepts

24. Internal Components Reliability/ Maintainability • Reliability represents a challenge to fusion, particularly for the core components. • RH strongly impacts machine availability (MTTR, MTBF) and affects in depth the design of many components/interfaces. It is needed from the design outset. • Proposed design solutions must be fully remotely maintainable. • Significant amount of time consuming demonstration and R&D often requiring design iteration and changes before we start to build. Large Port Concept Vertical Port Concept MMS Concept

25. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

26. Fusion Structural Materials Fusion reactors need high-temperature, radiation resistant materials In DEMO demanding operational requirements that are beyond today’s experience (including ITER and fission reactors), e.g., elevated operating temp., long periods of operation, higher irradiation damage and He accumulation, high reliability and availability, etc. In Fe for 1 MW/m2 and 1 FPY • 10 dpa • 100 appm He • 450 appm H • He/dpa ~ 10 appm/dpa RAFM: currently EUROFER 9%Cr [1W 0.14Ta 0.2V] steels (reference for DEMO)

27. The IFMIF Facilitywill allow qualifying materials under fusion spectrum Medium Flux Low Flux Deuteron Beam Liquid Li Jet High Flux Beam Spot (20x5cm2) In DEMO for 1 MW/m2 and 1 FPY • 10 dpa (in Fe) • 100 appm He • 450 appm H • He/dpa ~ 10 appm/dpa • Accelerator driven Li(d,n) source • 2 x 125mA 40MeV deuteron beams • Liquid Li target (~15m/s) subject to 10MW 1GW/m2 • Full range of PIE facilities • Designed to reach ~150dpa within a few years of full power operation Lack-of irradiation facilities with adequate n-spectrum (14 MeV + He) • Deuteron beams: • 2 x 125 mA • Ed = 40 MeV • Neutron production: •  1.1  1017 s -1 • Test volumes: • high flux: 0.5 L > 20 dpa/fpy • medium flux: 6 L > 1 dpa/fpy, • low flux: ~8 L 0.1-1 dpa/fpy EVEDA Phase in progress (as part of the BA with Japan Reduced-cost/ reduced performance options are being explored Source: U. Fischer

28. Outline • Incentives for developing fusion • The next frontier ITER and the role of other machines • Roadmap to fusion energy • DEMO Main Technical Challenges • Power exhaust • Power extraction and tritium breeding (blankets) • Radiation resistant structural materials • Summary

29. Summary • Fusion has a tremendous potential • ITER must be a success and it will answer open physics questions related to burning plasmas • There are still several challenges to be overcome for DEMO, especially for the core components (divertor, blanket) and materials. • Demonstration of fusion electricity by 2050: challenging but possible • In Europe the roadmap for the exploitation of fusion is being revisited. Expected a tighter coordinated effort with clearer focus and more technology orientation • W7-X will demonstrate the quality expected from stellarator optimisation • If we succeed, with fusion, we handover to future generations a clean, safe, sustainable power source.

30. Who I am! Thanks for your attention • Born 28.5.1960, married with two children (16 and 11) • Degree in Nucleal Engineering, Polytechnic of Milan 1985 • Ph.D. UCLA 1989 (Fusion Eng. and Applied Plasma Physics) • Post-Doc Fellowship EU Commission, Fusion 1990-92 • NET Team, 1992-93 • ITER Team, 1994-2006: Divertor and plasma interfaces • EFDA Garching, 2006-2007: Field Coordinator Vessel/ In-Vessel • F4E Barcelona, 2008 –2010: Senior Advisor to Chief Engineer • F4E Garching, 2011-today: Head of EFDA Power Plant Physics and Technology Dept.