THERMAL-HYDRAULIC AND STRUCTURAL DESIGN OF THE TITAN-I REVERSED-FIELD-PINCH FUSION POWER CORE

Thermal-hydraulic and structural design of the first wall, blanket, an d shield of the deuterium-tritium fueled TITAN-I reversed-field-pinch (RFP) fusion reactor is presented. Taking advantage of the characteris tic low toroidal magnetic field of an RFP reactor, liquid lithium is u sed as the primary coolant to remove the thermal energy at an elevated temperature, thereby realizing a high power conversion efficiency of 44%. The use of liquid lithium has also led to a self-cooled design of the fusion power core in which the primary coolant is also the tritiu m breeder. The structural material is the vanadium alloy, V-3Ti-1Si. T ubular coolant channels are used in the first wall/blanket and rectang ular channels in the hot shield. These are laid along the much larger poloidal field to minimize magnetohydrodynamic (MHD) pressure drop. Al though the neutron wall loading of 18.1 MW/m2 is high, resulting in a radiation heat flux on the first wall of 4.6 MW/m2, three aspects of t he design have made the removal of the reactor power at high temperatu re possible. These are: (1) the use of small-diameter circular tubes a s coolant channels in the first wall, (2) the use of high-velocity MHD turbulent flow in the first-wall coolant tubes, and (3) thermal separ ation of the first-wall and blanket/shield coolant circuits, thereby a llowing different exit temperatures. The thermal-hydraulic design was optimized by a design code developed for this purpose. Detailed struct ural design was performed by the finite element code ANSYS. The coolan t inlet temperature is 320-degrees-C, and the coolant exit temperature s for the first-wall and blanket/shield coolant circuits are 442-degre es-C and 700-degrees-C, respectively. Lithium flow velocity in the fir st-wall coolant tubes is 21.6 m/s, and is less-than-or-equal-to 50 cm/ s in the blanket/shield coolant channels. The total pressure drop in t he first-wall coolant circuit is 10 MPa and in the blanket coolant cir cuit it is 3 MPa. The pumping power for coolant circulation is less th an 5% of the net electric output. The material stresses are well withi n the design limits. The TITAN-I design suggests the feasibility and a dvantage of liquid-metal cooling of high wall loading RFP fusion react ors.