Research on Optimum Design Parameters for the HTGR-GT Power Plant

A modular high-temperature gas-cooled reactor (HTGR) coupled with a closed cycle helium gas turbine is expected as one of the promising power generation plants due to inherent safety and economics. Effects of main design parameters, particularly gas pressure, on cycle thermal efficiency and power generation cost were examined for the block-type HTGR power plant. A previous design of 600 MWt reactor with inlet and outlet temperatures of 460 and 850°C and a gas pressure of 6 MPa was assumed as a reference design. A computer analysis program combining a core thermal design and a gas turbine cycle was developed. From the results of parametric analyses regarding both the pressure and the fuel channel diameter based on this program, the reactor pressure vessel (RPV) cooling flow ratio of 1% was clarified to be sufficient. With increasing pressure, pressure drop decreased, and consequently, a higher cycle thermal efficiency and a lower power generation cost were achieved. Namely, it was clarified that an optimal pressure exists at around 8 MPa, which is different from the existing generally employed pressure of 6 or 7 MPa. In addition, the effects of fuel cost escalation were examined.