ReNeW PMI Theme PFC Panel Report

Transcription

1 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

2 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.

3 ReNeW PMI PFC Organization Review requirements development thrusts for the next years To project robust PFC design and development we created the ~ 1000 MWe DEMO key PFC parameters: Mid-plane Γn-max =3 MW/m 2 FW φ-max= 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) Solid surface and design (Wong) 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) ITER design as an initial example

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

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

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

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

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

9 heat flux in [MW/m^2] 2007: HHF test of optimized HEMJ mockup Test conditions: 10 MW/m 2 30s / 30s sharp power ramp Current Distribution of the Heat Flux used in Efremov T He,in 550 C, 10 MPa, mfr 7 g/s time in [s] Tile temperature rise after 89 cycles* --> tile probably partially detached. He Loop and thimble still intact. Post examination underway 2007 overall results: successful HHF tests of optimized HEMJ mockup 10 MW/m 2 (survived 100 thermal cycles, heat flux 30s-30s sharp ramp, w/o damages) *n required ~ Post-examined at FZJ [T. Hirai, G. Ritz] Castellation: cracks parallel to heat flux, W defect

10 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

11 W CFC negligible erosion ELM induced erosion of CFC and W with the 0.5 MJ/m 2 limit cracking of pitch fibres 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/ negligible damage melting of tile edges melting of tile surface droplets bridging of tiles crack formation mitigated ELMs in ITER unmitigated ELMs in ITER * Δt = 500 µs M. Roedig

12 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

13 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)

14 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

15 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

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18 PFC Matrix PFC Gaps: To Develop Understanding for the Construction of Robust PFC Components Thoeory & Modeling Existing/Upgrade/ New Test stands Chamber & Div. heat flux Steady state Example 1 Transient Solid surface design Liquid surface design Example 2 Tritium in solid, mix materials Maintenance Innovations Example 4 Existing Upgraded Confinement facilities Example 3 New Confinemet Facility 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 C, W-alloy C Design guidelines: FW heat flux ~0.5 MW/m 2, Max. heat flux ~10 MW/m 2, ELMs with rise time of µs, energy flux ~0.5 MJ/m 2

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

20 PFC Matric Example 1 PFC Matrix Example 2 PFC Gaps: To Develop Understanding for the Construction of Robust PFC Components Liquid surface design issues Configuration (Ext. chan., e.g. SXD,snowflakes) In chamber MHD effects Fluid flow MHD Heat flux limits Liquid surface substrate design Thermal limits Engineering design margin Impurity control and cleanup Plasma performance modifications Existing/Upgraded/New Test Stands Construct high B-field facilities for fast flow and capillary flow Perform high heat flux LM experiments at tokamak-relevant high B-field Study feed, drain manifolds Study eroion and corrosion lifetime Study T retention/migration IFMIF to test substrate material Study impurity control and cleanup

21 PFC Matrix Example 3 PFC Gaps: To Develop Understanding for the Construction of Robust PFC Components Tritium in solid, mix materials Tritium permeation/migration Materials/irradiation Safety limits Accountancy Existing/Upgraded Confinement Facilities Validate understanding of tritium transport and inventory on PFC materials Experiments with innovative and irradiated PFC materials Testing of tritium diagnostics Develop and test permeation barriers Test interface joining materials, initiate material qualification

22 PFC Matrix Example 4 PFC Gaps: To Develop Understanding for the Construction of Robust PFC Components Innovations: Advanced structural materials Surface materials innovation Advanced heat removal designs Theory & Modeling Model advanced materials: SiC/SiC, refractory alloys (e.g. W, Mo..) Model C, B coating and BW-surface Model new innovative heat removal proposals, e.g. liquid metal heatpipes

23 Potential PFC panel recommended Research Thrusts, version 5, 2/19/09 Small Medium Large 1. Liquid surface options 1,3,5,4 2,6* 2. W surface option 2,3,6,1,4 3. Helium heat transfer 1,2,8,5 4. PFC diagnostics development 5. Existing/Upgraded/New Test Stands: Heloops, heat flux, materials 6. New confinement facility (Does it need to be DT?) 7. Upgrade existing confinement device for hot walls 8. Modeling for predictive capability 1,2,3,8,5,4 6* 2 1,3,8,5,4 1,6,4 3,6,4 1,3,8,5,6,4 Very rough range: Small $2-3 M, medium $10-30 M, large ~$100M per year *Some of the research thrusts could cost in the small scale but they will need a medium cost device to work on or demonstrate 1. Wong, 2. Majeski, 3. Doerner, 4. Merrill, 5. Milora, 6. Leonard, 7 Lipschultz,8. Youchison

24 Conclusions We have identified that with presently available materials for ITER water cooled PFC components are already pushed to the edge of acceptable performance When extended to DEMO with RAFM steel as structural material and He as the coolant, disruptions will have to be avoided and ELMs will have to be mitigated or eliminated. Generation of robust PFC design will be a significant challenge, and could be by itself a major Research Thrust. Requirements and issues for physics, solid and liquid surface design, heat transfer and components testing and analysis, tritium, safety and RAMI, PFC surface material, maintenance, RAMI and development program areas have been identified. Innovative approaches on structural material, PFC material and heat removal will be needed A PFC matrix and a first collection of research thrust have been generated. We will continue to assess research thrust as a tool to meet our goal of have robust DEMO PFC components. PFC remains a Greenwald Priority Tier 1 area: solution not in hand, major extrapolation from current state of knowledge, need for qualitative improvements and substantial development for both short and long term