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

INDIAN FUSION ROAD MAP Power Plant DEMO SST-2 ITER Participation SST-1 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

DEMO Fusion Reactor Core Breeding Blanket 400-550°C Blanket Vertical Manifold ~320°C Vessel Neutron Shield ~320°C Divertor Vacuum Vessel ~100°C Magnet DEMO = Demonstration Fusion Reactor Plant -FZK

BLANKET Functions Tritium Breeding High grade heat extraction Radiation Shielding

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 indigenous Materials & Technologies. CHINA, EUROPE, INDIA, JAPAN, KOREA, RUSSIA & US

THE ITER DEVICE Parameters ITER DEMO Frame TBM Height: 25 m, Diameter: 28 m Frame TBM 1.66 m (h) x 0.48 m (w) x 0.54 m (t) Parameters ITER DEMO Surface Heat Flux (MW/m2) 0.27 0.5 Neutron wall Loading (MW/m2) 0.57 2.5 Pulse length (sec) Up to 3000 ~ continuous Duty cycle 0.25 - Avg. Neutron Fluence (MWa/m2) 0.1 (for initial 10 years) 7.5

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

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

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

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

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.

Structural Steels for TBM RAFM Steel : 9Cr W 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

Reduced Activation Ferritic Martensitic Steels (RAFMS) Typical Elements Wt. % Cr 8.80 – 9.20 C 0.10 – 0.12 Mn 0.4 0 – 0.60 V 0.18 – 0.24 W 1.0 – 1.20 Ta 0.07 – 0.10 N 0.02 – 0.04 O < 0.01 P < 0.002 S B < 0.001 Ti < 0.005 Nb Mo Ni Cu Al Si < 0.05 Co As+Sn+Sb+Zr < 0.03 Process : Vacuum Induction Melting (VIM) Typical RT 300 oC 500 oC UTS (Mpa) 640 – 680 520 – 560 400 – 440 YS (E 0.2%)(Mpa) 540 – 580 465 – 485 385 – 40 DBTT : < -70 oC 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

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

ODS alloys ODS alloys Advantages Disadvantages Disadvantages with FMS 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) ODS alloys Advantages Disadvantages 12-16% Cr ODS ferritic steel Higher temperature capability Better oxidation resistance Anisotropic mechanical properties Lower fracture toughness 9% Cr ODS ferritic/ martensitic steel Nearly isotropic properties after heat treatment Better fracture toughness Scalable fabrication Limited to temperature below ~700 C Marginal oxidation resistance at high temperatures  8-9.5 Cr , 1 % W and 0.3 %Y2O3 (50 nm size) without Titanium

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

Component-1 : U-Shaped First Wall Box Structure He Channel (Top plate cooling) He Channel First Wall HIPPING Or Investment Casting Channel 20 x 20 mm No. of Channel 64 Nos. Corner Radius Inside Channel 2.5 mm He Channel Overall Dimension: 1.66 m (h) x 0.48 m (w) x 0.54 m (t)

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 TBM FW Built-in Cooling Channels 300 18

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

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

Component-2 Top Plate Assembly of LLCB TBM Rib BY HIPPING Or Investment Casting

Dimensions of Top Plate-3 with Rib (He Inlet/Outlet) ISO View Plate Thickness 4 mm Rib Thickness 6 mm Rib Width Unspecified Corner Radius 2 mm All Dimensions are in mm

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

Dimension of Inner Back Plate Detail View B Channel Dimension 20 x 20 Total No. of Channel 32 Unspecified Corner Radius = 10 mm All Dimension Are in mm Section View A:A

Arrangement with Outer Back Plate 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

Dimension of Outer Back Plate

HIPPING Joint Properties EU Ref.

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)

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)

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)

LASER Welding (Reference EU R&D) YAG LASER Coolant Panels - 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

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

Major Milestones (1/2) Sr. No. Completion by: 1 Materials composition definition 12/2008 2 TBM Quality management system establishment (e.g., QA) 06/2009 3 Out-Of-Pile characterization of DEMO-relevant structural material and TBM fabrication process validation (at laboratory level) 12/2009 4 TBM system conceptual design 5 TBM Preliminary Safety Report (for each concept and dummy plug) 6 Small/medium size TBM mock-ups fabrication addressing critical components (industrial manufacture or, at least, industrially compatible manufacture) 12/2010 7 Small/medium size TBM mock-ups testing results 12/2011 8 Completion of data base for structural material and joints for use in design codes and codes & standards 6/2012

Major Milestones (2/2) 9 Detailed design of the first TBM system to be installed in ITER day one (1st Plasma) 06/2012 10 Completion of data base for structural material and joints under irradiation (at least, 3 dpa) 06/2014 11 End of fabrication of large size TBM mock-up and associated system 12 End of testing and qualification of large size TBM mock-up and associated system in appropriate facilities 12/2015 13 Delivery of TBM systems to ITER 12/2016 14 End of 1st TBM System acceptance tests (e.g., leakage tests, pressure tests, compatibility check with ITER interfaces) and Commissioning 12/2017 15 TBM Safety Report to be provided with QA records during construction and reception tests

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

Thank you

Damage rate [dpa/year] Irradiation Modes Fusion neutrons, fission neutrons, high energy protons: Strong differences in the production rates of impurities Defect poduction (in steels) Fusion neutrons (3-4 GW reactor, first wall) Fission neutrons (BOR 60 reactor) High energy protons (590 MeV) Damage rate [dpa/year] 20-30 ~ 20 ~ 10 Helium [appm/dpa] 10-15 ≤ 1 ~ 130 Hydrogen [appm/dpa] 40-50 ≤ 10 ~ 800

Electron Beam Welded 25 mm Plate 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

Electron Beam Welded 25 mm Plate 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

Effect of Post-Weld Heat Treatment on Hardness of Eurofer 97 EB Welds J.W. Rensman, E. Rigal, R. Meyder, A. Li Puma / ICFRM-12 (2005) 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.