Fuel and core design of super light water reactor with low leakage fuel loading pattern

An equilibrium core for the High Temperature Supercritical-pressure Light Water Reactor, now called the Super Light Water Reactor (Super LWR), has been designed. The fuel assemblies loaded in the peripheral region of the core are cooled with descending flow to achieve a high average coolant core outlet temperature. This flow scheme is compatible with a low leakage fuel loading pattern (LLLP) in which 3^rd cycle fuel assemblies are loaded in the core peripheral region. Stainless steel is used for fuel rod claddings and for structural materials. Watts correlations are used for predicting heat transfer in the core. They take into account the improved heat transfer for downward flow. It is found that the water rods with their downward flow need to be thermally insulated with thin ZrO₂ layer to keep the moderator temperature below the pseudo critical temperature and to reduce the thermal stress in water rod walls. An average coolant core outlet temperature of 500°C is achieved. The effects of various heat transfer correlations on the cladding surface temperature are evaluated.