The effect of the orientations of pebble bed in Indian HCSB Module Paritosh Chaudhuri Institute for Plasma Research Gandhinagar, INDIA CBBI-16, Sept. 2011, Portland, USA

1.) Introduction 2.) Helium Cooled Ceramic Breeder(HCCB) concept 3.) Radiation Heat Transfer Analysis using ANSYS 4.) Performance Analysis 5.) Summary, Conclusions and Future Work Outline

Lead-Lithium cooled Ceramic Breeder (LLCB)  Tritium Breeder: Lithium Ceramic pebbles; PbLi  Coolant: PbLi (multiplier and breeder);  FW coolant: Helium Gas;  Structural Material: Reduced Activation FMS  Purge gas: Helium, used for T extraction from CB (LLCB TBM in one half of ITER port) Helium Cooled Ceramic Breeder (HCCB)  Tritium Breeder: Lithium Ceramic pebbles;  Multiplier : Beryllium Pebbles;  Coolant : helium gas;  Structural Material: Reduced Activation FMS  Purge gas: Helium T extraction from CB (to participate as TBM Partner) Indian Blanket Concepts

Helium Cooled Ceramic Breeder(HCCB) concept

HCSB Concept (Toroidal-Radial Orientation) Features:  Similar to other solid breeder concepts.  With slight variance in the Tritium Breeder and Neutron multiplier bed design (Radial increase in the breeder bed thickness) Objective: -To increase the tritium breeding by accommodating more breeder material (with optimization of multiplier material volume) - To minimize the radial temperature gradient in the pebble beds

HCSB TBM (Exploded View) Inner Back-Plate First-Wall Bottom-Plate Assembly Breeder Units Grid-Plate Assembly Pipes (inlets & outlet) Flexible supports Top-Plate Assembly Outer Back-Plate Supports Keys

Input: Neutronic heat generation in HCSB TBM

Performance Analysis

Pebble Bed Arrangement (Toroidal-Radial) Pebble will settle down at the bottom, keeping some void space between the pebbles and top cooling plate.

no gap Temperature Distribution gap with radiative HT gap, no radiation Max. temp. 557  CMax. temp. 813  C Max. temp. 928  C

Temperature Distribution at different Locations Temperature (  C) at different locations of ceramic breeder ABCDEFGH No Gap (Conduction) With Rad Emissivity = With Gap (without Rad)

Temperature Distribution in HCSB TBM Radiation with different CB Emissivities Temperature (  C) at different locations of ceramic breeder ABCDEFGH Emissivity = Emissivity = Emissivity =

Temperature Distribution (Analytical Analysis)

From Toroidal -Radial  Poloidal-Radial orientation Toroidal-Radial Poloidal-Radial

Comparison between two different orientations Poloidal-Radial Toroidal-Radial Surface Area: m 2

Temperature Distribution in Poloidal-Radial pebble bed Toroidal-Radial view Toroidal-Poloidal view

Transient Thermal Analysis on HCSB TBM CBBeFMS Pol-RadConduction Pol-TorConduction Radiation Empty

 In Toroidal-Radial orientation of pebble bed, the area of the cooling plate (heat transfer area) attached to the pebble bed is very large.  If the pebbles are settle down at the bottom, creating a finite gap between the cooling plate and the top surface of the pebbles, the large heat transfer area can not involve in transferring heat from CB to coolant. This leads to increase in CB temperature.  In Toroidal-Radial orientation of pebble bed, settling down of pebbles would not effect the heat transfer between the CB and coolant. Summary and Conclusions

Effect of the He purge gas to be introduced in the Radiative heat transfer analysis. Simulation and experimental comparison between various packing arrangements. Safety analysis of Blanket Modules. Fabrication of small scale mock-ups to demonstrate structural and pebble bed integrity. Future Work

Backup Slides

Schematic of HCCB module and breeder unit HCSB Concept

2-D representation of radial-poloidal cross section of a breeder unit HCSB Concept 3/3

HCSB TBM (Preliminary Design) 2/3 FW is cooled by two counter-flowing helium circuits. Circuit 1 of the He flow channels have openings at the edge face of the FW and Circuit 2 has the channel openings on the inner face of the FW. First Wall of HCCB Ceramic Breeder: Li 4 SiO 4, Li 2 TiO 3 (pebble form) Multiplier: Beryllium / Beryllides Structure: RAFMS Coolant: Helium Purge Gas: Helium + %H 2

Helium cooling circuits for FW In C-13 In C-7 Out C-9 Out C-5 In C-11 Out C-3 In C-14 In C-1 Out C-7 In C-3 In C-5 Out C-14 Out C-1 In C-9 Out C-16 In C-2 In C4- In C-12 In C-6 In C-8 In C-15 In C-10 Out C-10 Out C-15 Out C-8 Out C-6 Out C-12 Out C-4 Out C-2 In C-16 FW Slot - Total number of channels: 64- Number of circuits: 2 - Number of passes per circuit: 8- Number of channels per passes: 4 - Channel dimension: 20x20 mm - Pitch: 25.5 mm - Rib thickness: 5.5 mm

Helium Flow path in HCCB

Helium Flow Distribution in HCCB

Grid Plate Assembly (HCSB TBM)

Top Plate assembly for HCSB TBM Inlet Outlet Helium-flow path First-Wall Top-Plate Assembly Top-Plate 4mm-thk Bottom-Plate 4mm-thk R Channels 4mm-thk