Session VII. Panel Discussion

Session VII. Panel Discussion “ Is lithium PFC viable in magnetic fusion reactors such as ITER?” [11:00 – 12:30] Panel Members: R. Goldston (ITER/Reactor), F. Groeschel (IFMIF), Y. Hirooka (IFE), S. Mirnov (Innovative Ideas), G. Mazzitelli (Tokamaks), M. Ono (Chair), D. Ruzic (LiMIT), F. L. Tabarés (non-tokamak), A. Ying (TBM) 11:00 – 11:45: Comments from Panel Members 11:45 – 12:30: Panel Discussion

Issues for Lithium Reactor Applications 1. Handling Divertor High Heat Flux 2. Removal of D, T, Impurities 3. Divertor Steady-State Heat Removal 4. Liquid Lithium Flow in Magnetic Field 5. Long Term Lithium Corrosion 6. Flowing Liquid Lithium Safety 7. Compatibility with Hot Wall

Flowing Liquid Lithium Divertor Tray an Ultimate Solution? Necessary “Ingredients” are Coming Together?! Divertor Heat and Particle Flux Edge Plasma 000000000000 Core Reacting Plasma D, T, Impurities First Wall / Blanket At 500°C – 700°C? Lithium is not likely to be on this surface. Flowing Liquid Lithium System LL Purification and Cooling System ~ 400°C Scrape Off Layer LLDT Cooling line LL Circulation Pump Flowing Liquid Lithium Divertor Tray (LLDT) 200°C – 400°C ~ 200°C

Can Liquid Lithium Surface Handle High Heat Flux? Promising Properties of Liquid Lithium • Liquid Lithium Properties: • • Light 0.534 g / cc • • High heat capacity (4.22 J/g K) • • Low viscosity < 0.5 water above 400°C • • Low Melting Point of 180.4°C • • High Boiling Point of 1342°C • • Low vapor pressure at high T • • Very large vaporization energy ~ 23 kJ / g • (J.E. Selle, ORNL) Heat Flux Questions: • Liquid lithium appears to handle high heat flux well. CDX-U, LiMIT, LLL, Goh • Lithium reduces divertor heat flux? NSTX • Can liquid lithium carry out necessary steady-state heat flux? IFMIF experience? • Can liquid lithium divertor handle ultra high transient heat flux such as the ELM heat flux issue? Transient 100 MW/m2 Partial lithium vaporization. • Vaporization necessary ultimately? (e.g., Nagayama) Divertor Heat and Particle Flux Flowing LLDT 200°C - 600°C?

Can D, T, Impurities Removed via LLD System IFMIF Experience? Divertor Heat and Particle Flux D,T, Impurity Removal Questions and Issues: • Argon bubble removal of hydrogen? M. Kondo • IFMIF EVEDA – O,N, T <10 weppm in real time. Cold trap, nitrogen trap, hydrogen trap, • IFMIF – local loop idea for impurity removal seems quite practical. D, T, Impurities Flowing LLDT 200°C - 600°C ~ 600°C LL Purification and Cooling System Cooling line LL Circulation Pump ~ 200°C

Can Liquid Lithium Remove Steady-State Divertor Power? IFMIF Experience? Divertor Heat and Particle Flux • Liquid Lithium Properties: • • High heat capacity (4.22 J/g K) • • Low viscosity at high T Steady-State Heat Removal Questions and Issues: • 130 l /s, 4.5 ton, 250 – 350°C, 10 MW, IFMIF EVEDA (F. Groeschel) • • D, T, Impurities Flowing LLDT 200°C - 600°C ~ 600°C LL Purification and Cooling System Cooling line LL Circulation Pump ~ 200°C

Can Liquid Lithium Circulated within Magnetic Field? Blanket Module Experience, Thermo-Electric Effect? Divertor Heat and Particle Flux Liquid Lithium Circulation in B Questions and Issues: • TBM - MHD forces dominate viscous and inertial forces for the PbLi flow in magnetic field. Modeling and Experiment (R&D) needed. A. Yoing • T-E effect must be taken into account - could greatly help the flow (D. Ruzic) • L. Zakharov ‘s comment on flow issues. D, T, Impurities Flowing LLDT 200°C - 600°C ~ 600°C LL Purification and Cooling System Cooling line LL Circulation Pump ~ 200°C

Longer Term Lithium Corrosion Edge Plasma 000000000000 Lithium Corrosion Questions and Issues: • TBM material – corrosion rate – Er2O3 coationg is effecting against lithium. O, N impurities are corrosive. C impurity is OK. ( M. Kondo) • • Core Reacting Plasma First Wall / Blanket At 500°C – 700°C? Lithium is not likely to be on this surface. Scrape Off Layer Flowing Liquid Lithium Divertor Tray (LLDT) 200°C – 400°C

Can Flowing Hot Liquid Lithium System Be Safe? IFMIF Experience? How to Avoid Contact with Water / Air? Divertor Heat and Particle Flux Liquid Lithium Safety Questions and Issues: • • • D, T, Impurities Flowing LLDT 200°C - 600°C ~ 600°C LL Purification and Cooling System Cooling line LL Circulation Pump ~ 200°C

Is Lithium Utilization Compatible with Hot First Wall? Edge Plasma 000000000000 Hot Wall Questions and Issues: • Avoid lithium contamination of first wall? • Perhaps lithium dust, jet, evaporation etc., into the main chamber may be fine with hot wall? • Would lithium and its compound eventually end up in the colder divertor area? Core Reacting Plasma First Wall / Blanket At 500°C – 700°C? Lithium is not likely to be on this surface. Scrape Off Layer Flowing Liquid Lithium Divertor Tray (LLDT) 200°C – 400°C

Session VII. Panel Discussion

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