ReNeW PMI Theme PFC Panel Report Organization First question at the - PowerPoint PPT Presentation

ReNeW PMI Theme PFC Panel Report • Organization • First question at the beginning: What are we doing? • Technologists to physicists: What heat fluxes will the DEMO have? • Physicists to technologists: What are your design limits? • Both sides agreed: We have significant challenges ahead. • The team then worked on requirements and issues of different areas. • Generated the PFC Matrix showing issues and needs for different areas. • We do have a draft PFC related research thrusts Panel team members : C. Wong ( GA), B. Lipschultz (MIT), T. Leonard (GA), R. Majeski (PPPL), D. Youchison (SNL), B. Merrill (INL) R. Doerner (UCSD), S. Milora (ORNL) US Department of Energy OFES Research Needs Workshop (ReNeW) University of California, Los Angeles March 2 – 6, 2009

PFC is a Tier 1 priority Greenwald Priority Tier 1: solution not in hand, major extrapolation from current state of knowledge, need for qualitative improvements and substantial development for both short and long term • Plasma Facing Components • Materials Plasma Facing Components : Understand the materials and processes that can be used to design replaceable components that can survive the enormous heat, plasma and neutron fluxes without degrading the performance of the plasma or compromising the fuel cycle.

ReNeW  PMI  PFC Organization Review…requirements…development… thrusts… …for the next 15 -20 years To project robust PFC design and development we created the ~ 1000 MWe DEMO key PFC parameters: Mid-plane Γ n-max =3 MW/m 2 FW φ -max= 0.5-4.0 MW/m 2 (TBD) Div φ -max = 10 MW/m 2 (steady state) + 20 MW/m 2 (10-100s) (pulses TBD) Panel member focused areas: • Physics (Lipschultz and Leonard) ITER design as • Solid surface and design (Wong) an initial example • Liquid metal and design (Majeski) • Surface heat transfer and components testing and analysis (Youchison) • Tritium, safety and RAMI (Merrill) • Surface materials (Doerner) • Maintenance and development program (Milora)

EU Roadmap Divertor Development towards ITER & DEMO [P. Norajitra et al.]

Intro (6): Assumptions for DEMO Design from EU For DEMO:  ELMs have to be supressed,  VDEs and disruption „unlikely events“ * (Vertical Displacement Events) * * Number of events in ITER * (Edge Localized Modes) constant load for DEMO [T. Ihli, Summer School 2007, Karlsruhe, Germany]

Intro (5): Example Divertor Cassette for Model C from EU Replacement scheme [P. Norajitra et al.]

Reference Design: He-cooled modular divertor with jet cooling (HEMJ) 1300 ° C (RCT, irr.) Temperature windows Divertor target plates WL10 10 MW/m 2 with modular thermal Thimble shield (W/W alloy) Inboard 700 ° C Dome and structure 700 ° C outl. creep rup. (ODS RAFM) 600 ° C He coolant strength 600 ° C inl. (DBTT, irr.) ODS Euro Structure 300 ° C (DBTT, irr.) Outboard 18 } 5 Divertor cassette [T. Ihli] 9-Finger module 1-Finger module

2006 HHF test results (mockup #4) EFREMOV under FZK contract HEMJ-J1c Overall results: • W-tile: Non-castellated, russ. W • WL10 thimble  No suddenly • W/W joint: STEMET 1311 and/or completely • W-Steel joint by Cu casting broken mock-up, He data: • 10 MPa i.e. no brittle • 13.5 g/s (∆P 0.31 MPa*) failure. • Tin = 520-570 ° C • Tout = 550-600 ° C  Nor was a Results : recrystallisation of • 10 cycles each at 4,6,10,11 the thimble MW/m2  ok observed in any • Failure in W/W joint after 6 cycles W-tile at ~13 MW/m2 mock-up. • He Loop and thimble still intact Detached area *) about 0.085 MPa equivalent at 6.8 g/s nominal W-thimble Conical Cu- cast lock Steel ring Crack in thimble, growing from inside

2007: HHF test of optimized HEMJ mockup 2007 overall results: Test conditions:  successful HHF • 10 MW/m 2 tests of optimized • 30s / 30s sharp power ramp HEMJ mockup 10 12 MW/m 2 10 (survived 100 heat flux in [MW/m^2] 8 thermal cycles, 6 30s-30s sharp 4 ramp, w/o 2 damages) 0 T He,in 550 ° C, 10 MPa, mfr 7 g/s 0 10 20 30 40 50 60 70 time in [s] • Tile temperature rise after 89 cycles* --> tile probably partially detached. • He Loop and thimble still intact. • Post examination underway *n required ~ 100 - 1000 Post-examined at FZJ [T. Hirai, G. Ritz] Castellation: cracks parallel to heat flux, W defect

Wall loads on plasma facing components in ITER Thermal load during ELMS:  1 GWm -2 ,  t = 500 µs, 1 Hz  high cycle thermal fatigue critical area W CFC M. Roedig flat tile design monoblock

ELM induced erosion of CFC and W with the 0.5 MJ/m 2 limit cracking of pitch fibres negligible CFC erosion PAN eros. PAN erosion PAN erosion > 100 shots > 50 shots > 10 shots 0 0.5 1.0 1.5 energy density* E / MJm -2 heat flux factor P ·  Δ t / MWm -2 s 1/2 0 20 40 60 negligible melting of melting of droplets tile edges tile surface bridging of tiles damage W crack formation mitigated * Δ t = 500 µs ELMs in ITER M. Roedig unmitigated ELMs in ITER

PFC team went through a detailed identification of PFC requirements and issues Seven PFC panel areas: 1. Physics, 2. Solid surface and design, 3. Liquid metal and design 4. Surface heat transfer and components testing and analysis 5. Tritium, safety and RAMI, 6. surface materials, 7. maintenance and development program

ReNeW  PMI  PFC  Solid surface & design: Wong Review…requirements…development… thrusts …for the next 20 years Requirements: • Configure surfaces to reduce peak heat flux, material erosion and deposition • Components life time: FW 4years (TBD), divetor 2 years (TBD) • Disruption and transient events tolerance (TBD) even for unlikely events • Robust components to withstand all Demo operating scenarios, including all operational & transient E&M loads and structural and thermal stresses (including effects from neutron irradiation, cyclic fatigue, thermal creep, fracture toughness, fracture mechanics effects), while providing a design margin of 1.3 (TBD)* • Adjust to major divertor configuration change if recommended? • Divertor design to maximize flexibility, surface can be shifted back and forth by ± 5 ° when required by operation. • Design with removable chamber first wall (TBD)? • Assess the renewable low-Z surface on W option? • Design with high thermal efficiency • Develop predictive capability via modeling and analysis ( Not covered or provided in the Greenwald report)

ReNeW  PMI  PFC  Solid surface & design: Wong Review…requirements…development… thrusts …for the next 20 years Development needs: • Demo design: Use a projected Demo design to define the pre-conceptual design with gradual increase of details: including physics, configuration, segmentation, routing, maintenance, structural support…etc. • Industrial connection: Establish connections with industry on PFC components design, fabrication and testing of different scale of PFC components • Modeling: If necessary develop PFC relevant design codes, coupled with dedicated analysis codes and commercial design codes • Fusion materials design codes • Connections: Continue to work with physicists, first wall material designers, heat transfer and components developers and testing professionals

PFC team went through a second round on PFC requirements and issues PFC requirements and issues were prepared for different areas We found that the two VG format was too limiting, two page write-ups of issues on each of the seven PFC related areas were generated. Seven PFC panel areas: 1. Physics, 2. Solid surface and design, 3. Liquid metal and design 4. Surface heat transfer and components testing and analysis 5. Tritium, safety and RAMI, 6. surface materials, 7. maintenance and development program

PFC Matrix PFC Gaps: To Develop Understanding for the Construction of Robust PFC Components Thoeory & Existing/Upgrade/ Existing Upgraded New Confinemet Modeling New Test stands Confinement Facility facilities Chamber & Div. heat flux Steady state Example 1 Transient Solid surface design Liquid surface design Example 2 Tritium in solid, Example 3 mix materials Maintenance Innovations Example 4 • Inputs to be developed jointly with PWI and other panels • Inputs to be developed jointly with other panels • Possible temperature range: RAF/M-350 to 550 C, ODFS Tmax-700-800 C, W-alloy 700-1300 C • Design guidelines: FW heat flux ~0.5 MW/m 2 , Max. heat flux ~10 MW/m 2 , ELMs with rise time of 125-250 µs, energy flux ~0.5 MJ/m 2

PFC Matrix Example 1 (physics) PFC Gaps: To Develop Understanding for the Construction of Robust PFC Components (Physics) Theory & Modeling Define chamber spatial and temporal heat loads Chamber & Divertor heat flux 1 st principles modeling Conventional Extended channel(s) (e.g. SXD, Divertor physics, integrated with PMI effects, 1 st principles modeling snowflakes) Transients: Startup/shutdown Define start/up & shutdown parameters Model suppression and elimination of high ELMs power ELMs Disruption Model disruption avoidance and mitigation, Other off normal events: eliminate off normal events MARFE, Improve neutral and photon modeling H-L transition Model avoidance of MARF, H-L transition heat load Define occasional ELMs and heat dump locations and parameters by 1 st principles modeling Heat dumps