Thermal hydraulic analysis of the TPX plasma facing components

The purpose of the Tokamak Physics Experiment (TPX) is to develop and demonstrate steady state tokamak operating modes that can be extrapolated to reactor conditions. TPX will have a double null divertor with an option to operate in a single null mode. The maximum input power will be 45 MW and the pulse length will be 1000 s. The major and minor radii will be 2.25 m and 0.5 m respectively. The material of plasma facing components (PFCs) will be carbon fiber composite (CFC). The plasma facing components (PFC) cooling will be provided by water at an inlet pressure of 2 MPa and inlet temperature of 50°C. The heat flux on the PFCs will he less than 0.2 MW/m² on line of sight shields to 7.5 MW/m² on divertor surfaces. The maximum allowable temperature on the divertor surface is 1400°C and 600°C on all other PFCs. The attachment method, the type of CFC, the coolant flow velocity and the type of coolant channel is chosen based on the surface heat flux. In areas of highest heat flux, heat transfer augmentation will be used to obtain a safety margin of at least 2 on critical heat flux. An extensive thermal flow analysis has been performed to calculate the temperatures and pressure drops in the PFCs. A number of R&D programs are also in progress to verify the analysis and to obtain additional data when required. The total coolant flow rate requirement is estimated to be about 50 m³/min (12000 gpm) and the maximum pressure drop is estimated to be less than 1 MPa