Heterogeneous annular core concepts for plutonium-thorium fuels in pressure-tube heavy water reactors

Lattice and core physics studies were carried out to analyze the performance characteristics of various heterogeneous concentric annular seed-blanket cores in pressure tube heavy water reactors (PT-HWR) using plutonium/thorium fuel bundles in a once-through thorium (OTT) cycle. These studies complement others carried out recently. PT-HWR's are an attractive operational technology for the initial exploitation of the energy potential in thorium and also for consuming accumulated stockpiles of plutonium found in spent LWR fuel. The high neutron economy and on-line refueling capability of PT-HWR's allows much flexibility to optimize the use of Pu/Th fuels for producing power, and for creating a stockpile of U-233 for use in future thorium breeder reactors. The combination of low-fissile blanket fuel and higher fissile-content seed fuel in a heterogeneous core can enhance breeding relative to a homogeneous core with one fuel type. (author)