Nuclear Core Design of a High-Converting LWR with Thorium Fuel

A conceptual nuclear design was done for a high converting pressure-tube type light water cooled reactor (HCPLWR) based on once-through thorium fuel cycle. Fuel rod bundles are designed as hexagonal lattice array in a similar size of those of CANDU, and fuel pins are in the same size with conventional PWR fuel pins. Driver fuel bundles and blanket fuel bundles are loaded in separate coolant channel, which have different reloading cycle scheme with different thermal-hydraulic conditions. Two optimized design options showed higher conversion ratio than that of conventional reactors and more economical fuel cycle. In the aspect of safety, both fuel temperature coefficient and moderator temperature coefficient are negative. A negative reactivity is also guaranteed when safety injection of light water is assumed into the dry calandria as an additional reactor shutdown device. (author)