1. 1 ISFNT-10, Portland, OR, September 12-16, 2011 Overview of the Design and R&D of the ITER Blanket System Presented by A. René Raffray Blanket Section Leader Blanket Integrated Product Team Leader ITER Organization, Cadarache, France with contributions from M. Merola and members of the ITER Blanket Integrated Product Team 10 th International Symposium on Fusion Nuclear Technology (ISFNT-10) Portland, OR, September 12-16, 2011 The views and opinions expressed herein do not necessarily reflect those of the ITER Organization

2. 2 Blanket Effort Conducted within BIPT Blanket Integrated Product Team ITER Organization DA’s - CN - EU - KO - RF - US Include resources from Domestic Agencies to help in major design and analysis effort. Direct involvement of procuring DA’s in design -Sense of design ownership -Would facilitate procurement ISFNT-10, Portland, OR, September 12-16, 2011

3. 3 Blanket System Functions Main functions of ITER Blanket System: Exhaust the majority of the plasma power. Contribute in providing neutron shielding to superconducting coils. Provide limiting surfaces that define the plasma boundary during startup and shutdown. ISFNT-10, Portland, OR, September 12-16, 2011

4. 4 Modules 1-6 Modules 7-10 Modules 11-18 ~1240 – 2000 mm ~850 – 1240 mm Shield Block (semi-permanent) FW Panel (separable) Blanket Module 50% 40% 10% Blanket System ISFNT-10, Portland, OR, September 12-16, 2011

5. 5 Blanket System Layout -The Blanket System consists of Blanket Modules (BM) comprising two major components: a plasma facing First Wall (FW) panel and a Shield Block (SB). - It covers ~600 m 2. -Cooling water (3 MPa and 70°C) is supplied to the BM by manifolds supported off the vacuum vessel behind or to the side of the SB. ISFNT-10, Portland, OR, September 12-16, 2011

6. 6 Blanket Design Major evolution since the ITER design review of 2007 -Need to account for large plasma heat fluxes to the first wall -Replacement of port limiter by first wall poloidal limiters -Shaped first wall -Need for efficient maintenance of first wall components. -Full replacement of FW at least once over ITER lifetime -Remote Handling Class 1 Design change presented at the Conceptual Design Review (CDR) in February 2010 and accepted in the ITER baseline in May 2010. Post-CDR effort focused on resolving key issues from CDR, particularly on improving the design of the first wall and shield block attachments to better accommodate the anticipated electromagnetic (EM) loads. ISFNT-10, Portland, OR, September 12-16, 2011

7. 7 Blanket System in Numbers Number of Blanket Modules: 440 Max allowable mass per module:4.5 tons Total Mass: 1530 tons First Wall Coverage: ~600 m 2 Materials: -Armor:Beryllium -Heat Sink:CuCrZr -Steel Structure:316L(N)-IG n-damage (Be / heat sink / steel): 1.6 / 5.3 / 3.4 (FW) 2.3 (SB) dpa Max total thermal load:736 MW ISFNT-10, Portland, OR, September 12-16, 2011

8. I-shaped beam to accommodate poloidal torque Design of First Wall Panel ISFNT-10, Portland, OR, September 12-16, 2011

9. First wall Shield block Plasma Toroidal direction Toroidal gap : 16 mm on the inboard Inboard wall Horizontal view Why Shaping of First Wall is Needed? ISFNT-10, Portland, OR, September 12-16, 2011 The heat load associated with charged particles along the field lines is a major component of heat flux to first wall.

10. First wall Toroidal direction 5 mm The two situations are equally probable  So chamfering on both sides is necessary First wall 5 mm First wall Toroidal direction Two Sides Need to be Considered ISFNT-10, Portland, OR, September 12-16, 2011

11. First wall Toroidal direction First wall 5 mm 16 mm  ISFNT-10, Portland, OR, September 12-16, 2011 Shaping the First Wall

12. 12 Plasma RH access Exaggerated shaping -Allow good access for RH -Shadow leading edges Final Shaping of First Wall Panel Heat load associated with charged particles is a major component of heat flux to first wall. The heat flux is oriented along the field lines. Thus, the incident heat flux is strongly design-dependent (incidence angle of the field line on the component surface). Shaping of FW to shadow leading edges and penetrations. ISFNT-10, Portland, OR, September 12-16, 2011

13. 13 0176<= 1.3 MW/m²40% 1.4 MW/m² <=42<= 2.0 MW/m²10% 3.0 MW/m² <=162<= 3.9 MW/m²37% 4.0 MW/m² <=60 <= 4.7 MW/m²14% Total 440100% First Wall Panels: Design Heat Flux ISFNT-10, Portland, OR, September 12-16, 2011

14. 14 First Wall Finger Design SS Back Plate CuCrZr Alloy SS Pipes Be tiles Normal Heat Flux Finger: q’’ = ~ 1-2 MW/m 2 Steel Cooling Pipes HIP’ing Enhanced Heat Flux Finger: q’’ < ~ 5 MW/m 2 Hypervapotron Explosion bonding (SS/CuCrZr) + brazing (Be/CuCrZr) ISFNT-10, Portland, OR, September 12-16, 2011

15. 15 First Wall Analysis Detailed blanket design activities on-going in parallel with supporting analyses in preparation for PDR. They address EM, thermal, thermo-hydraulic and structural aspects based on ITER Load Specifications and requirements. Design cases are categorized according to their probability of occurrence and allowable stress or temperature levels depend on the event category. The capability of the design to withstand the design number of cycles for each of the events must be demonstrated. Schematic of EHF FW finger and Example Thermal Stress Results ISFNT-10, Portland, OR, September 12-16, 2011 More details on thermo-mechanical analysis of EHF FW from M. Sviridenko’s poster presentation on Wednesday

16. 16 Shield Block Design Slits to reduce EM loads and minimize thermal expansion and bowing Poloidal coolant arrangement. Cooling holes are optimized for Water/SS ratio (Improving nuclear shielding performance). Cut-outs at the back to accommodate many interfaces (Manifold, Attachment, In-Vessel Coils). Basic fabrication method from either a single or multiple-forged steel blocks and includes drilling of holes, welding of cover plates of water headers, and final machining of the interfaces. ISFNT-10, Portland, OR, September 12-16, 2011 More details on EM slit optimization study from J. Kotulski’s poster presentation on Wednesday

17. 17 Thermo-mechanical analysis indicates that the stress levels are acceptable and that the temperature level <~350°C, as illustrated by the example results for SB 1 shown here. Shield Block Analysis ISFNT-10, Portland, OR, September 12-16, 2011 More details on cooling optimization from Duck- Hoi Kim’s poster presentation on Tuesday

18. 18 Shield Block Attachment 4 flexible axial supports Keys to take moments and forces Electrical straps to conduct current to vacuum vessel Coolant connections ISFNT-10, Portland, OR, September 12-16, 2011

19. 19 Flexible Axial Support 4 flexible axial supports located at the rear of SB, where nuclear irradiation is lower. Compensate radial positioning of SB on VV wall by means of custom machining. Adjustment of up to  10 mm in the axial direction and  5 mm transversely (on key pads) built into design of the supports for custom-machining process. Cartridge and bolt made of high strength Inconel-718 Designed for 800 kN preload to take up to 600 kN Category III load. ISFNT-10, Portland, OR, September 12-16, 2011

20. 20 Example Analysis of Flexible Cartridge: Fatigue Assessment of M66 Main Thread for BM 18 ISFNT-10, Portland, OR, September 12-16, 2011 Equivalent stress, Pa - SDC-IC 3322: Fatigue usage fraction - Total stress range - Elastic strain range (SDC-IC 3323.1.1) Linearization of equivalent stress Δσ, МPаT, o C 2.Sy,МPа2.Sy,МPа Δε, %[N]nV 190415019440.8651114000.078 Max. Von Mises stress 952 MPa (m) (Pa) 5111 cycles 92.2%-margin Elastic analysis – Design load for axial supports in Cat.II: 504 kN radial force, T = 150 0 C The number of Cat.II events will be limited to 400 (cf. VV load specification)

21. Example Analysis of Flexible Cartridge: Collapse Load Assessment for BM 18 (immediate plastic collapse – SDC-IC 3211.2) ISFNT-10, Portland, OR, September 12-16, 2011 21 Elastoplastic analysis Reaction in pilot node from tensile force vs. displacement Tension (Allowable (II) = 1.2 MN) LF,collapse III = 3.00 > LF,criteria III = 1.2  Margin 150% LF,collapse II = 3.57 > LF, criteria II = 1.5  Margin 138% Symmetric assembly Friction coefficients: 0.4(metal - metal) 0.6 (metal – ceramic) Analysis model Total strain (tension force 600 kN) Max. total strain 0.43% Collapse load: 1800 kN 1800 kN/600 kN 1800 kN/504 kN

22. 22 Toroidal Forces Poloidal Forces Shear Keys Used to Accommodate Moments from EM Loads ISFNT-10, Portland, OR, September 12-16, 2011

23. 23 Keys in Inboard and Outboard Modules Each inboard SB has two inter-modular keys and a centering key to react the toroidal forces. Each outboard SB has 4 stub keys concentric with the flexible supports. Bronze pads are attached to the SB and allow sliding of the module interfaces during relative thermal expansion. Key pads are custom-machined to recover manufacturing tolerances of the VV and SB. Electrical isolation of the pads through insulating ceramic coating on their internal surfaces. ISFNT-10, Portland, OR, September 12-16, 2011

24. 24 Example Analysis of Inter-Modular Key Analysis of the inter-modular keys indicate stresses above yield (~172 MPa at 100°C) in the case of Category III load. Limit analysis then performed to check margin. ISFNT-10, Portland, OR, September 12-16, 2011

25. 25 Limit Analysis of Inter-Modular Key Reasonable load factors of 1.5 for the pads and 1.9 for the neck of the key are obtained based on limit analysis under Category III load with 5% plastic strain. Eddy Forces Applied 1.725 MN ISFNT-10, Portland, OR, September 12-16, 2011

26. 26 Analysis of Outboard Stub Key Stub key for BM#11 Worst-case EM loads (from PDR Protocol): -FMr II = 855 kN (cat. II) -FMr III = 1014 kN (cat. III) ISFNT-10, Portland, OR, September 12-16, 2011 Plus (mainly taken by axial supports): - FMpII = 300 kN -FMpIII = 360 kN Stub key Pad Reaction forces from forces due to radial moment, FMr Stub key Pad

27. 27 Limit Analysis of Stub Key of BM #11 ISFNT-10, Portland, OR, September 12-16, 2011 1.27 (Pa) Stress redistribution at LF collapse III = 1.27 Plastic strain at LF collapse III = 1.27 Max. plastic strain: 5.01% -LF collapse III = 1.27 > LF criteria III = 1 (Margin 27%) - LF collapse II = 1.510 > LF criteria II = 1.171 (Margin 29%)

28. 28 Electrical Straps Each SB is electrically joined to the VV by two electrical straps, formed and louvered from two sheets of CuCrZr alloy to achieve flexibility. Each strap is bolted on to the rear of a SB using M8 bolts. The socket is welded to the VV. An M20 bolt inserted through the front face of the SB connects the straps to the vessel socket via a compression block. One electrical connection can handle up to 180 kA of electrical current. Socket now welded on VV Cu alloy strap M8 bolt M20 bolt Blanket side VV side ISFNT-10, Portland, OR, September 12-16, 2011

29. 29 Blanket Manifold ISFNT-10, Portland, OR, September 12-16, 2011 A multi-pipe configuration has been chosen, with each pipe feeding one or two BM’s replacing the previous baseline with a large single pipe feeding several BM’s -Higher reliability due to drastic reduction of number of welds and utilization of seamless pipes. -Higher mechanical flexibility of pipes  reduction of space reservation at back of BM. -Superior leak localization capability due to larger segregation of cooling circuits. -Elimination of drain. -Reduction of cost: -Well established manifold technologies. -Simplification of Vacuum Vessel manufacturing due to elimination of heavy anchoring plates. -Must be balanced with cost associated with higher number of valves required for leak localization (2 valves per circuit).

30. Blanket Remote Handling ISFNT-10, Portland, OR, September 12-16, 2011 On-Rail Module Transporter -Shield blocks designed for ITER lifetime (semi-permanent component) -First wall panels to be replaced at least once during ITER lifetime (designed for 15,000 cycles). -Both are designed for remote handling replacement (FW: RH Class 1). -Blanket RH system procured by JA DA. -RH R&D underway. More details from S. Mori’s oral presentation on Monday and S. Shigematsu’s poster presentation on Thursday.

31. 31 Supporting R&D A detailed R&D program has been planned in support of the design, covering a range of key topics, including: -Critical heat flux (CHF) tests on FW mock-ups. -Experimental determination of the behavior of the attachment and insulating layer under prototypical conditions. -Material testing under irradiation. -Demonstration of the different remote handling procedures. A major goal of the R&D effort is to converge on a qualification program for the SB and FW panels. -Full-scale SB prototypes (KODA and CNDA). -FW semi-prototypes (EUDA for the NHF FW Panels, and RFDA and CNDA for the EHF First Wall Panels). -The primary objective of the qualification program is to demonstrate that: -Supplying DA can provide FW and SB components of acceptable quality. -Components are capable of successfully passing the formal test program including heat flux tests in the case of the FW panel. ISFNT-10, Portland, OR, September 12-16, 2011

32. 32 Example R&D for Hypervapotron CHF (RFDA) The R&D program in support of the EHF hypervapotron CHF testing was conducted at the Efremov Institute, RF. The results confirm the CHF margin of 1.4 for the EHF FW under an incident heat flux of 5 MW/m 2. ISFNT-10, Portland, OR, September 12-16, 2011 More details from I. Mazul’s oral presentation on Tuesday

33. –Each DA must demonstrate technical capability prior to start procurement. –2 phase approach: I. Demonstration/validation joining of Be/CuCrZr and SS/CuCrZr joint (done) II. Semi-prototype production/validation of large scale components (on-going) FW Pre-Qualification Requirements 6 Fingers in 1 to 1 scale 2 slopes, 4 facets

34. NHF FW Pre-Qualification Program (EUDA, on-going) Engineering support activity Manufacturing Development activity Standard NHF 1 medium scale mock-up to study Be tile sizes + checking end-of-finger configuration 1 semi-prototype for 1 MW/m 2 heat flux (S-NHF) Upgraded NHF 3 small-scale mock-ups for checking performance under Heat Flux 1 semi-prototype for 2 MW/m 2 heat flux (U-NHF) CuCrZr heat sink Be tiles SS beam

35. 35 Summary The Blanket design is extremely challenging, having to accommodate high heat fluxes from the plasma, large EM loads during off-normal events and demanding interfaces with many key components (in particular the VV and IVC) and the plasma. Substantial re-design following the ITER Design Review of 2007. The Blanket CDR in February 2009 has confirmed the correctness of this re-design. Effort now focused on finalizing the design work. Parallel R&D program and formal qualification process by the manufacturing and testing of full-scale or semi-prototypes. Key milestones: -Preliminary Design Review: Nov. 29 – Dec. 1, 2011 -Final Design Review in late 2012. -Procurement to start in early 2013 and should last till 2019. ISFNT-10, Portland, OR, September 12-16, 2011