Helium Cooling Ceramic Breeder Blanket Design For Fusion DEMO(HCCB-DEMO)

The basic definition of Helium Cooling Ceramic Breeder DEMO (HCCB-DEMO) was proposed by Southwest Institute of Physics in 2009.The basic feature of HCCB-DEMO are characterized by:1) fusion power is 2000MW and electic power is 800MW; 2) burning time is about 8h with inductive operation; 3) NBI and RF system are used for current drive or stability control; 4) NB3Sn superconductor magenetic system; 5) It includes 18 TF coils and 6 PF coils, central solenoid (CS); 6) self-sustainable tritium breeding. Blanket is an important component in fusion power plant, which is required to achive high capacity of tritium breeding in the limit space of DEMO and transfer heat from plasma to electric power output.Helium Cooling Ceramic Breeder (HCCB) is a reliality blanket concept, HCCB Testing Blanket Module(TBM) designed by China will be a mock-up as DEMO Blanket tested in International Thermonuclear Experiment Reactor (ITER). In recent years, based on the development of R&D in breeding blanket, such as fusion materials, fabrication technologies and safety assessment, the old Blanket design need to be updated to satisfy the functional and technological requirements. The main design feature of updated HCCB Blanket are characterized by:1) Neutronic Wall Loading is 2.3MW/m2, Surface Heat Flux is 0.43MW/m2;2) 8MPa Helium as coolant with inlet temperature of 300℃ and outlet tmperature of 500℃,0.3MPa Helium with 0.1 vol.H2 as purge gas.3) Chinese Low Ferritic steel CLF-1 as structure material, Li4SiO4 pebble with single size as tritium breeder, Beryllium pebble with binary size as neutron multiplier, Tungsten alloy as plasma surface facing materials; The blanket consists of the First Wall (FW), Caps, Stiffening Grids (SGs), Breeder Units (BUs), Back plates. The FW is a U-shaped plate made of CLF-1 with rectangular cooling channels built in it. The top and bottom of the FW are welded to a radial-toroidal Caps respectively to form a blanket box.49 SGs are welded into the inner wall of the FW and Caps with the radial-toroidal and radial-poloidal plates to reinforce the blanket structure.The space between the grids is determined by the mechanical strength of the box wall. Totally 30 BUs (5 in poloidal direction and 6 in toroidal direction) are inserted into the spaces divided by the SGs. One BU have two canister with symmetric distribution and back plates. The breeder (Li4SiO4) pebble bed and the neutron multiplier (Be) pebble bed are separated with the U-shape cooling panels which are connecting with the back plates. The ceramic breeder pebbles of Li4SiO4 were filled in the two U-shaped Cooling Plates (CPs) which consist of a canister. The Be pebble bed surrounds 2 U-shaped Li4SiO4 pebble beds in overall. The maniflods created by the Back Plates provide the collection and distribution of coolant and purge gas.Based on a 5x5 internal structure design, the key blanket structure and thermal-hydraulic parameters was been researched by CFD method. The result indicated that one BU need two breeder region and 5x5 internal stucture need to be updated to 6x5 internal structure.Based on the final 6x5 design,3D neutronic calculation was beed performed, the result showed that TBR could reach 1.15 which was satisfying the tritium breeding requirement. Thermal-hydraulic anlysis with theory model and 3D CFD method was been also performed on separated component include FW, SGs, Cap and BU. The result showed that the maximum temperature of each components was in material limit temperature. The thermal boundary conditions of each separated components were obtained by thermal-hydraulic analysis on integrated components model.A hydraulic analysis focused on coolant distribution manifolds was performed. Based on the preliminary analysis results, the structure was been optimized to ensure the coolant distribution more evenly. The pressure drop of each maniflods was also been calculated based on the modified structure.Thermal-mechanical analysis focused on the Blanket Box and BU in normal operating condition and accidental condition was been performed. Based on the RCC-MR 2007, the stress in each model could meet the structure design requirements.