Test Blanket Module: Steels & Fabrication Technologies

1. Test Blanket Module: Steels & Fabrication Technologies E. Rajendra Kumar and TBM Team Institute for Plasma Research Bhat, Gandhinagar WS&FT-08, 21st July 2008, IPR

2. INDIAN FUSION ROAD MAP Power Plant 2050 Fusion Power Reactor DEMO 2035 - Qualification of Technologies - Qualification of reactor components & Process SST-2 2020 Indigenous Fusion Experiment ITER Participation 2005 scientific and technological feasibility of fusion energy SST-1 2004 Steady State Physics and related technologies TBM Program Prototype Programs 1986 ADITYA Tokamak

3. DEMO Fusion Reactor Core Breeding Blanket 400-550°C Blanket VerticalManifold ~320°C Vessel Neutron Shield ~320°C Divertor VacuumVessel ~100°C Magnet DEMO = Demonstration Fusion Reactor Plant -FZK

4. BLANKET Functions • Tritium Breeding • High grade heat extraction • Radiation Shielding

5. TBM Program in ITER • The ITER Basic Device has Shielding Blanket, but no Breeding Blanket • ITER mission : “ITER should test tritium breeding module concepts that would lead in a future reactor to tritium self-sufficiency, the extraction of high grade heat and electricity production.” • Breeding Blankets will be tested in ITER, by inserting Test Blanket Modules (TBM) in specially dedicated ports All the ITER Parties have their own TBM program and developing indigenousMaterials & Technologies. CHINA, EUROPE, INDIA, JAPAN, KOREA, RUSSIA & US

6. THE ITER DEVICE Height: 25 m, Diameter: 28 m Frame TBM 1.66 m (h) x 0.48 m (w) x 0.54 m (t)

7. Indian TBM Concepts • Lead-Lithium cooled Ceramic Breeder (LLCB) • Tritium Breeder: Lithium-Titanate pebbles • Breeder Coolant: Lead-Lithium eutectic alloy  (multiplier and breeder) • Structural Material : Reduce Activation FMS • Solid Type: Helium Cooled Ceramic Breeder (HCCB) • Tritium Breeder: Lithium-Titanate / Lithium Silicate pebbles • Multiplier : Beryllium Pebbles • Structural Material : Reduce Activation FMS • Coolant : helium gas

8. U-shaped First wall Box structure Top Plate Support He Purge Outlet He Purge Inlet Shear Keys Outer Back Plate He Inlet Poloidal 1660 He Outlet Radial 536 Pb-Li Inlet Pb-Li Outlet Bottom Plate Lead-Lithium cooled Ceramic Breeder (LLCB) TBM Toroidal 480

9. Structural material IN-RAFMS Breeder Pb-17Li, Li2TiO3 Neutron reflector / shield SS 316 LN IG MHD insulation Al2O3 or Other choice Primary coolant Helium and Pb-Li He inlet/outlet 350 / 480 oC Helium pressure 8 MPa He pressure drop in module 0.3 MPa Pb-Li inlet/outlet 350/480 oC Li-6 enrichment 90 % LLCB TBM Parameters LLCB 1.66 m (h) x 0.484 m (w) x 0.54 m (t) Helium as Purge gas for Tritium extraction

10. TBM Materials • Structural material : Reduced Activation Ferritic Martensitic Steel • (RAFMS) and ODS • Tritium Breeder : • Solid : Li4SiO4, Li2TiO3 • Liquid : Pb-17Li • Enriched Lithium : Li-6 (30 – 90 %) • Neutron multiplier : Be, Be12Ti, Pb • Composite Material : SiCf/SiC (FCI) • Coatings : Be, Alumina, Erbium oxide coatings • Neutron Shielding and External Piping : SS 316 LN-IG

11. Key Material Issues in Fusion Devices • The 14 MeV neutrons produce transmutation nuclear reactions and atomic displacement cascades inside the materials • Damage and transmutation imply degradation of physical and mechanical properties of materials ( Swelling, Hardening, LD, LCS, LFT..) • DEMO: Radiation damage @ First Wall, End of life: 100 - 150 dpa (5 yr) Transmutation to Helium: 1200 -1800 appm He • The existing sources of 14 MeV neutrons have a small intensity and do not allow us to get important damage accumulation in a reasonable time. • It is necessary to simulate irradiation by 14 MeV neutrons (@ 550 C), by using either fission neutrons, or high energy protons. • Presently, Materials are irradiated with fission neutrons and with high-energy protons. Results are interpolated for fusion irradiation conditions.

12. Structural Steels for TBM • RAFM Steel : 9CrW Ta V Si, C • Composition tailored to reduce activation and waste • Operational Temperature window: 300-550°C • To be used as structural material for the TBM and in DEMO blankets • Oxide dispersion strengthened (ODS) Steels • (Potential Candidate to replace RAFMS) • Operational Temperature window: 350-650°C

13. Reduced Activation Ferritic Martensitic Steels (RAFMS) Process :Vacuum Induction Melting (VIM) Plates of dimensions: (in mm) (i) 1700 L x 1500 W x 12-15 T (ii) 1700 L x 1500 W x 25-30 T Rectangular tubes: (18mm x 18 mm) Powder & Wire form (for welding ) Quantity Required: Each TBM (Typically) : ~ 5 Ton To develop 8 TBMs in 15 years : ~ 40 - 50 Ton IGCAR & MIDHANI jointly developing

14. RAFMS Development : Critical Issues • Characterization and understanding of degradation due to neutron irradiation ( ~ 550 C)  3 -15 dpa (engineering database for TBM design, fabrication and TBM licensing) • Major Issues: • Development of Reliable joints manufacturing process (HIP, EBW, LW etc..) • Compatibility with Breeder Materials (Li-ceramics, flowing Pb-Li in magnetic filed) • Anti-Corrosion / Anti-Permeation Barriers development • Creep-Fatigue Interaction due to high temperature cyclic operation (data validation) • High Temperature Design Criteria as per the ITER SDC (RCCMR & ASME) • LONG TERM R&D for the Development of fully qualified LAFMS material • Modeling & Simulation • Chemical Composition • Characterization Mock-up fabrication • Optimization of joining techniques • Neutron irradiation • Industrial Production

15. Long Term Needs ODS alloys • Disadvantages with FMS • DBTT decrease after irradiation at Tirr < 400°C; • The welds need heat treatments • Upper operating temperature limited by creep strength: Tmax 550°C • Possible solution: Tmax in range 550-650 °C by powder metallurgy Route (ODS)  8-9.5 Cr , 1 % W and 0.3 %Y2O3 (50 nm size) without Titanium

16. Manufacturing Technologies adopted for TBM HIPPING / INVESTMENT CASTING EB Welding Hybrid (MIG/LASER) TIG Welding LASER Welding Testing Methods • Ultrasonic testing • X-ray / γ-ray testing • Dye Penetrant testing • Helium leak tightness

17. Component-1 : U-Shaped First Wall Box Structure He Channel (Top plate cooling) He Channel First Wall HIPPING Or Investment Casting He Channel Overall Dimension: 1.66 m (h) x 0.48 m (w) x 0.54 m (t)

18. Typical Dimensions (Reference EU Trials) HIPPING • First Wall thickness : ~ 25 – 30 mm • Cooling channels : 15-18 x 15-18 mm2 (5 - 6 mm rib) • Top & Bottom covers : 30 – 32 mm • Stiffening plates / flow divider wall thickness : 5 – 8 mm 1000 oC, 130 MPa Options 200 TBMFW Built-in Cooling Channels 300 18

19. F82H as recieved Grain Size # G：5 Grain Size：60mm 1040 ºC x 2hr x 150MPa Grain Size #G：2 Grain Size：170mm TBM FW mockup fabrication (EU - References) 200mm X 200mm X 100mm (height) 19

20. 200 Built-in Cooling Channels 300 Japanese Trials with RAFMS (F82H) Horizontal Channels 20

21. Component-2 Top Plate Assembly of LLCB TBM Top Plate 1 Top Plate 2 Top Plate 3 Rib BY HIPPING Or Investment Casting

22. Dimensions of Top Plate-3 with Rib (He Inlet/Outlet) ISO View All Dimensions are in mm

23. Component-3 : Manifold Arrangement with Inner Back Plate Inner Back Plate Breeder First Wall He Inlet for Back Plate He Channel Inner Back Plate He Outlet for Back Plate

24. Dimension of Inner Back Plate Detail View B Unspecified Corner Radius = 10 mm All Dimension Are in mm Section View A:A

25. Manifold Arrangement with Outer Back Plate Outer Back Plate First Wall Inner Back Plate He Outlet for Back Plate He Channel Outer Back Plate He Inlet for Back Plate

26. Dimension of Outer Back Plate

27. HIPPING Joint Properties EU Ref.

28. Investment casting Investment casting is a potentially attractive alternative to HIP for first-wall, grid plate and manifold fabrication • Reduces the need for extensive joining which should improve reliability (joints are typically the origin of structural failures) • Reduces the amount of NDE needed (few joints). • Potentially less expensive than other fabrication methods. • Complex castings of 9-10 Cr steels have been produced with mechanical properties similar to those of wrought products (Ref: Valves & Steam Turbine applications)

29. EB-Welding Sound structural welds: Free of cracks, low pores For High Depth Welding: High voltage: 150 kV, Welding current: 72 mA, Travel speed: 0.3 m/min 40 mm and weld width 2 mm. Macrography of Eurofer / 316LN EBW (1.5 mm thick)

30. Major Tasks in EBW development • Development of welding procedure for thick RAFMS plates • Optimization of Welding process (current density, speed, environ.) • Characterization of weld joints (ITER-SDC  RCC-MR and ASME codes) • Radiography Test • Effect of Post-Weld Heat Treatment on Hardness (needs optimization) • Effect of neutron Irradiation on weld joints (Microstructures, Mechanical Properties (TS, DBTT, YS, FT) • Optimization of EBW process in actual TBM mock-ups (In real joint configurations)

31. LASER Welding (Reference EU R&D) YAG LASER - Laser power: 4 kW - Travel speed: 0.35 m/min - Focal length: 150 mm - Twin spot with d = 2.1 mm Plate – Plate welding 5 - 8 mm to 12 – 15 mm • Penetration of the melt run ranges typically from 4 to 8 mm (WS = 130 cm/min). • Metallurgical analysis: hot cracks (max. 1.2 mm) and gas pores (max.  0.7 mm). • RAFMS / EUROFER is sensitive to hot cracking. Coolant Panels

32. LASER Welding on TBM Mock-up Trials Join realized in 2 passes (Top & Bottom) Mode I: Successive and opposite direction of the passes; Mode II : Simultaneous and same direction of the passes Assembly mode I & II Clamping Conditions (Reference EU R&D) Dissimilar Joints (RAFMS/SS 316 LN) SP- Fusion Butt welding (YAG LASER) > 2 KW Pipes Dia: 75 – 85 mm, thick = 3 - 6 mm - Metallographic - Destructive / non-destructive tests

34. Major Milestones (2/2)

35. Summary • Materials Requirement and related Manufacturing technologies for TBM development has been projected • The fabrication technologies development for TBM need to be initiated through mock-ups and prototype fabrication and testing • The qualification according to codes and standards needs to be finalized and harmonized as per the ITER requirements • The budget for the TBM Program is available. • We invite R&D centers to initiate the developmental activities for a committed delivery to meet the ITER time schedule

36. Thank you

40. Irradiation Modes • Fusion neutrons, fission neutrons, high energy protons: • Strong differences in the production rates of impurities

41. Effect of 300°C Irradiation on Eurofer97 Base and EB Weld Metal Tensile Ductility J.W. Rensman / NRG Irradiation Testing: Report on 300°C and 60°C Irradiated RAFM Steels (2005) 25 mm Plate Electron Beam Welded 25 mm Plate

42. Effect of 300°C Irradiation on Eurofer97 Base and EB Weld Metal Impact Properties J.W. Rensman / NRG Irradiation Testing: Report on 300°C and 60°C Irradiated RAFM Steels (2005) 25 mm Plate Electron Beam Welded 25 mm Plate

43. Effect of Post-Weld Heat Treatment on Hardness of Eurofer 97 EB Welds • Research needs: • No systematic study of all variables in the literature. There is a need to understand the controlling variables to optimize weld and PWHT for irradiation response. • Irradiation testing of very fine grained HAZ. • Irradiation testing of base and weld metal with multiple PWHTs. J.W. Rensman, E. Rigal, R. Meyder, A. Li Puma / ICFRM-12 (2005)