Overview of LLCB TBM for ITER Paritosh Chaudhuri

Overview of LLCB TBM for ITER Paritosh Chaudhuri Institute for Plasma Research Gandhinagar, INDIA CBBI-16, 8 - 10 Sept. 2011, Portland, USA

Intruduction In India, development of Lead-Lithium Ceramic Breeder (LLCB) blanket is being performed as the primary candidate of Test Blanket Module (TBM) towards DEMO reactor. The LLCB TBM will be tested from the first phase of ITER operation (H-H phase) in one-half of a ITER port no-2. The Indian TBM R&D program is focused on the development and characterization of materials: structural (IN-RAFMS), breeding materials (Pb–Li, Li 2 Ti. O 3) and development of technologies for Lead-Lithium Systems, Helium Cooling Systems, Tritium Extraction Systems, TBM manufacturing and coatings.

Indian TBM Program India is developing Lead-Lithium cooled Ceramic Breeder (LLCB) TBM for testing in ITER Port No-2 with position of TBM Leader. Lead-Lithium cooled Ceramic Breeder (LLCB) Ø Tritium Breeder: Lithium Titanate; Ø Coolant: Pb-Li eutectic alloy (multiplier and breeder) Ø FW coolant: Helium Gas; Ø Structural Material : Reduced Activation FMS Ø Helium purge gas for T extraction from CB

LLCB TBM Internal Arrangements Dimensions ~1. 66 m (P) x. 484 m (T)x. 496 m (R) Structural Material FMS (IN-RAFMS) 28 mm thick Breeder Pb. Li, Li 2 Ti. O 3 Total Power Deposition ~ 0. 857 MW NWL ~ 0. 78 MW/m 2 Coolant Pb. Li and Helium

TBM SYSTEM - Schematic 5

LLCB TBM Neutronic Analysis

Input parameters for LLCB TBM neutronic calculations ØFusion Power : 500 MW, Neutron Wall load : 0. 78 MW/m^2 ØPulse duration is 400 sec with pulse repetition time 1800 sec ØMajor and Minor radius of plasma: 6. 3/ 2. 1 m ØStructural Material: IN-RAFMS (Eurofer as a reference material) ØShield Material: - SS-316 (65%) and water (35%) ØVacuum Vessel: Borated SS-316 cooled with water ØBlanket materials: -Pb-Li Eutectic (90 % Li-6) (Breeder, Multiplier and coolant) -Li 2 Ti. O 3 (60 % Li-6, Packing fraction 60%)(Breeder Material) -He (Coolant for the First wall)

LLCB TBM in ITER sector model ØA 15 degree sector of the ITER machine has been constructed. The shield and vacuum vessel has been made using the intersection of concentric tori and concentric cylinders. ØTBM dimensions are taken as 1. 66 x 0. 484 x 0. 518 m^3 (pol x tor x rad ). TBM geometry has been modeled using the parallel planes. ØA 20 cm thick water jacket has been placed around the TBM. 100 cm thick shield plug has been put after the TBM. Poloidal Radial view of ITER neutronic model (with LLCB TBM)

Power density profile & Total Power Deposition in LLCB TBM Total Power deposited in LLCB TBM is 0. 62 MW

Preliminary LLCB TBM shield block design Schematic Frame Assembly LLCB TBM + Shield Block in Frame assembly LLCB TBM Reference Solid TBM Sub-modules Shield block Shield Flange with lip seal ØThe TBM in ITER will attenuate the flux ~1 order magnitude ØTo reduce dose rates this flux should be further reduced (~106 n/cm 2 /s) for safety and maintenance purpose Ø The shield block consists of 60 % SS 316 LN and 40 % water (DM)

LLCB TBM Thermal Hydraulic

Thermal Hydraulics of ITER TBM Main Objectives: To optimize a suitable design of FW cooling w. r. t. Neutron wall load and heat flux. To estimate the temperature and thermal stresses of all materials used in the blanket module and ensure these values are within design limits. To keep the temperatures of ceramic breeder zones within the temperature window for effective Tritium release To optimize the flow parameters (velocity, pressure)

LLCB First Wall Structure 480 568 20 X 11 20 X 20 R 2. 5 28 Circuit-1 Circuit-2 Total number of channels - 64 Number of circuits (counter flow) – 2 Number of passes per circuit – 4 Number of channels per passes – 8 Pitch: 25. 5 mm (typical to all channels) Rib thickness between channels = 5. 5 mm

Power Deposition on LLCB TBM Analytical Model Input Parameters - Total Heat Load: 0. 616 MW - He inlet Temp: 300 C - He inlet pressure: 8 MPa - He velocity : 45 m/s - Pb. Li inlet Temp: 325 C - Pb. Li inlet pressure: 1. 2 MPa - Pb. Li velocity: 0. 1, - 0. 5 m/s Assumptions - Flow is Steady and incompressible - Flow is turbulent Output: - Radial temp. profile in all zones; - Pb. Li velocity, Pressure Drop profile, outlet temp.

Radial Temperature Plot for LLCB TBM Temperature Distribution of LLCB TBM (for different V= 0. 1, 0. 2, 0. 3, 0. 5 m/s)

Radial temperature profile in different CB zones for Pb. Li velocity of 0. 1 m/s

Peak Temperature at different zones in LLCB TBM Peak Temperature at different zones in TBM (for Pb. Li velocity = 0. 1 m/s) Zone Name Temperature ( C) Analytical Analysis) CFD Analysis Be Surface 422. 21 462. 57 Be-FMS Interface 414. 53 453. 95 FMS-Insulator Interface 441. 69 455. 01 Insulator-Pb. Li Interface 439. 49 449. 37 Insulator-FMS Interface 442. 85 458. 30 FMS-CB Interface 438. 99 459 CB zone (5 th 489 Breeder) (5 th 491 Breeder)

Alternative Concept

R&D Activities under progress (1/2) Indian RAFMS Development: - Composition Achieved - Melts are under characterization (Microstructure & Mechanical properties) Lead-Lithium Technologies development: - Lead-Lithium production - Pb-Li Corrosion experiments - Full scale Pb-Li loop development Ceramic Pebbles Fabrication: -Lab scale pebbles (Lithium Titanate) successfully fabricated - Pebble bed characteristics are under investigation -Large scale production plans are under progress

R&D Activities under progress (2/2) Helium Loop development - ¼ the size loop development plan - Small scale TBM testing Tritium Extraction Systems development - H/D extraction from Helium purge gas - H/D extraction from Pb-Li - Permeation Analysis

Work under Progress RAFM steel is a structural material under development for fusion reactor applications. Several fabrication processes for the production of TBM subcomponents and assembly need to be investigated in the developmental program. For the fabrication of sub-components (first wall, stiffening plates, cooling plates and caps) using the Indian RAFMS different options are being considered to investigate its fabricability: HIP process, EB welding, Laser and Narrow Gap TIG welding.

Initial trials for First wall small scale mock-up by HIP process were carried out using stainless steel discs with pre-machined slots for making internal channels. Fig. 6 shows the hipped part. EB welding on 6 mm thick austenitic stainless steel plates. Welds of this structure cleared both ultrasonic examination and radiography. Virtually no distortion was observed in this structure. It is planned to make similar structures using RAFM steel plates to gain experience in fabrication.

Alternative approach for FW fabrication Cutting of straight square channel by wire EDM followed by hot bending. advantage of this approach is that there will be no mating surface and therefore, no lack of bonding. However, challenges remain in cutting such a long square channel by wire EDM.

Summary v Institute for Plasma Research (IPR), collaboration with Bhaba Atomic Research Centre (BARC), Indira Gandhi Centre for Atomic Research (IGCAR) and other research institutions and universities within India involve the R&D activities focusing on ITER-TBM systems development. v The major areas of R&D activities are: - Development of technologies of circulators, heat exchangers and diagnostics for Lead-Lithium Systems, HCS, LL, TES - Lead-Lithium Loop developments: - MHD studies: - Li 2 Ti. O 3 Ceramic Pebbles development v The Rp. Rs report on safety analysis have been submitted, further detail work is in progress.

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MHD pressure drop in LLCB TBM The MHD pressure drop is calculated with an analytical expression for fully developed laminar flow in a rectangular duct. Channel Parameters Channel Height (2 a) = 50 mm Channel Width (2 b) = 484 mm Insulation layer (A 2 B 2) thickness = 0. 2 mm Outer wall (A 1 B 1) thickness = 5 mm Channel length = 10 m Electrical conductivity : Pb-Li ~ 0. 7 e 6, Fe wall ~1. 4 e 6, Alumina ~ 1 e-9 With Flow dividers Hartmann number ~ 25000 Mean velocity is 0. 1 m/s MHD Pressure Drop (1)Without coating : 122. 5 k. Pa (2)With Alumina coating : 0. 432 k. Pa Considerably small MHD pressure drop inside TBM

2 D MHD Code: Velocity & induced field With alumina Without alumina Surface plot velocity profile More details in Poster NO: PO 1 -10, K. S. Goswami Velocity profile Further work: MHD effects in Manifolds & in fringe field Heat Transfer with MHD effects Crack analysis contour plot of induced magnetic field

Analysis with 2 -D MHD code • Fully developed MHD flow in a rectangular channel • Surrounded by various layers with different electrical properties • Similar to S. Smolentsev et al. (FED, 2005) • Velocity and induced magnetic field are calculated self consistently • No-slip condition at the liquid-solid interface • No induced magnetic field at the outer boundary of the computational domain

Validation of 2 -D MHD code Comparison with analytical results Ha & grid size J. R Hunt (1965) MHD code 100 (81 x 81, 12) 0. 1600 x 10 -2 0. 1588 x 10 -2 1000 (81 x 81, 12) 0. 4195 x 10 -4 0. 430 x 10 -4 10000 (81 x 81, 12) 0. 1240 x 10 -5 0. 1286 x 10 -5 10000 (161 x 161, 24) 0. 1240 x 10 -5 0. 1258 x 10 -5 25000 (81 x 81, 12) 0. 310 x 10 -7 0. 323 x 10 -7

Velocity profile for higher Ha