AbstractIn this paper we give thermal-hydraulic models of pebble bed. A code, THPBHR, developed by the present authors is briefly introduced. Radial cooling and poloidal direct cooling methods are given and discussed. The thermal-hydraulic calculations of them by THPBHR are given. Calculation results show that both cooling methods can meet the demands of blanket design. The heat transfer in the beds with poloidal cooling is better than with radial cooling, but the pressure drop is higher. The non-uniformity of outlet temperature is much higher with poloidal cooling.