Examination of Complicated Thermal Hydraulic Characteristics in Core Region of a PWR

Reactor coolant enters at cold-leg nozzles, goes down along the down-comer, changes flow direction and goes up passing through core region, and then exits hot-leg nozzles under normal operation of typical PWRs (Pressurized Water Reactors). Since temperature variance caused by inertia resistance and decay heat as well as pressure drop due to fuel assemblies are important and complicated in the core region, lots of efforts have been devoted to relevant design and evaluation.