Overview of LLCB TBM for ITER

Paritosh Chaudhuri

Institute for Plasma ResearchGandhinagar, 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, Li2TiO3) and development of technologies for Lead-Lithium Systems, Helium Cooling Systems, Tritium Extraction Systems, TBM manufacturing and coatings.

Indian TBM Program

Lead-Lithium cooled Ceramic Breeder (LLCB)

Tritium Breeder: Lithium Titanate; Coolant: Pb-Li eutectic alloy (multiplier and breeder) FW coolant: Helium Gas; Structural Material : Reduced Activation FMS Helium purge gas for T extraction from CB

India is developing Lead-Lithium cooled Ceramic Breeder (LLCB) TBM for testing in ITER Port No-2 with position of TBM Leader.

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 PbLi, Li2TiO3

Total Power

Deposition

~ 0.857 MW

NWL ~ 0.78 MW/m2

Coolant PbLi and Helium

5

TBM SYSTEM - Schematic

LLCB TBM Neutronic Analysis

Fusion Power : 500 MW, Neutron Wall load : 0.78 MW/m^2

Pulse duration is 400 sec with pulse repetition time 1800 sec

Major and Minor radius of plasma: 6.3/ 2.1 m

Structural Material: IN-RAFMS (Eurofer as a reference material)

Shield Material:- SS-316 (65%) and water (35%)

Vacuum Vessel: Borated SS-316 cooled with water

Blanket materials: -Pb-Li Eutectic (90 % Li-6) (Breeder, Multiplier and coolant) -Li2TiO3 (60 % Li-6, Packing fraction 60%)(Breeder Material) -He (Coolant for the First wall)

Input parameters for LLCB TBM neutronic calculations

Poloidal Radial view of ITER neutronic model (with LLCB TBM)

LLCB TBM in ITER sector model

A 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.

TBM dimensions are taken as 1.66 x0.484x0.518 m^3 (pol x tor x rad ). TBM geometry has been modeled using the parallel planes.

A 20 cm thick water jacket has been placed around the TBM. 100 cm thick shield plug has been put after the TBM.

Total Power deposited in LLCB TBM is 0.62 MW

Power density profile & Total Power Deposition in LLCB TBM

Preliminary LLCB TBM shield block design

The TBM in ITER will attenuate the flux ~1 order magnitude

To reduce dose rates this flux should be further reduced (~106 n/cm2 /s) for safety and maintenance purpose

The shield block consists of 60 % SS 316 LN and 40 % water (DM)

LLCB TBM + Shield Block in Frame assembly

LLCB TBMLLCB TBM

Shield block

Shield Flange with lip seal

Frame Assembly

Schematic

ReferenceSolid TBMSub-modules

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)

480568

20X20

20X11

R2.5

Circuit-1 Circuit-2

28

LLCB First Wall Structure

Total number of channels - 64Number of circuits (counter flow) – 2Number of passes per circuit – 4Number of channels per passes – 8Pitch: 25.5 mm (typical to all channels) Rib thickness between channels = 5.5 mm

Input Parameters

- Total Heat Load: 0.616

MW

- He inlet Temp: 300 C- He inlet pressure: 8

MPa

- He velocity : 45 m/s

- PbLi inlet Temp: 325 C

- PbLi inlet pressure: 1.2

MPa

- PbLi velocity: 0.1, - 0.5

m/s

Assumptions

- Flow is Steady and incompressible

- Flow is turbulent

Output:

- Radial temp. profile in all zones;

- PbLi velocity, Pressure Drop profile,

outlet temp.

Power Deposition on LLCB TBMAnalytical Model

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

Radial temperature profile in different CB zones for PbLi velocity of 0.1 m/s

Peak Temperature at different zones in LLCB TBM

Peak Temperature at different zones in TBM (for PbLi 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-PbLi Interface 439.49 449.37

Insulator-FMS Interface 442.85 458.30

FMS-CB Interface 438.99 459

CB zone 489 (5th Breeder)

491 (5th Breeder)

Alternative Concept

Exploded views of LLCB

First-Wall

Bottom plate assembly

Top plate assembly

Breeder assembly Outer & Inner back plates

Manifold

Pipes

Housings & keys

Exploded views of LLCB

First-Wall

Bottom plate assembly

Top plate assembly

Breeder assembly Outer & Inner back plates

Manifold

Pipes

Housings & keys

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

R&D Activities under progress (1/2)

Ceramic Pebbles Fabrication:-Lab scale pebbles (Lithium Titanate) successfully fabricated- Pebble bed characteristics are under investigation-Large scale production plans are under progress

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

R&D Activities under progress (2/2)

RAFM steel is a structural material under development for fusion reactor applications.

Several fabrication processes for the production of TBM sub-components 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.

Work under Progress

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.

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.

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.

Alternative approach for FW fabrication

Summary

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: - Li2TiO3 Ceramic Pebbles development

The RpRs report on safety analysis have been submitted, further detail work is in progress.

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 .

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Thank you

MHD pressure drop in LLCB TBM

Channel ParametersChannel Height (2a) = 50 mm Channel Width (2b) = 484 mmInsulation layer (A2B2) thickness = 0.2 mmOuter wall (A1B1) thickness = 5 mmChannel length = 10 m

Electrical conductivity :

Pb-Li ~ 0.7e6, Fe wall ~1.4e6, Alumina ~ 1e-9

Hartmann number ~ 25000

Mean velocity is 0.1 m/s

MHD Pressure DropMHD Pressure Drop(1)Without coating : 122.5 kPa(2)With Alumina coating : 0.432 kPa

Case 2b Ha Dp(Al2O3) Dp(Fe)mm kPa kPa

1 484 25652 0.432 1232 242 12826 0.853 2503 161 8551 1.273 623

With Flow dividers

Considerably small MHD pressure drop inside TBM

The MHD pressure drop is calculated with an analytical expression for fullydeveloped laminar flow in a rectangular duct.

2D MHD Code:Velocity & induced field

With alumina Without alumina

Further work:MHD effects in Manifolds &

in fringe fieldHeat Transfer with MHD

effectsCrack analysis

More details in Poster NO: PO1-10, K.S. Goswami

Surface plot velocity profile

contour plot of induced magnetic field

Velocity profile

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

Ha & grid size J.R Hunt (1965) MHD code

100 (81x81,12) 0.1600 x 10-2 0.1588 x 10-2

1000 (81x81,12) 0.4195x10-4 0.430x10-4

10000 (81x81,12)

0.1240x10-5 0.1286 x 10-5

10000 (161x161,24)

0.1240x10-5 0.1258 x 10-5

25000 (81x81,12)

0.310x10-7 0.323 x 10-7

Comparison with analytical results

Velocity profile for higher Ha