Subchannel Analysis of Wire Wrapped SCWR Assembly

Abstract

Application of wire wrap spacers in SCWR can reduce pressure drop and obtain better mixing capability. As a consequence, the required coolant pumping power is decreased and the coolant temperature profile inside the fuel bundle is flattened which will obviously decrease the peak cladding temperature. The distributed resistance model for wire wrap was developed and implemented in ATHAS subchannel analysis code. The HPLWR wire wrapped assembly was analyzed. The results show that: (1) the assembly with wire wrap can obtain a more uniform coolant temperature profile than the grid spaced assembly, which will result in a lower peak cladding temperature; (2) the pressure drop in a wire wrapped assembly is less than that in a grid spaced assembly, which can reduce the operating power of pump effectively; (3) the wire wrap pitch has significant effect on the flow in the assembly. SmallerHwire/Drodwill result in stronger cross flow a more uniform coolant temperature profile, and also a higher pressure drop.

Generating Hexahedral Mesh for Wire-wrapped Fuel Assembly With RBF Mesh Deformation Method

“…Compared to the fuel assembly with grid-type spacers, wire-wrapped fuel assembly could generally achieve a lower pressure drop with a compact fuel rod packing (Todreas and Kazimi, 2011). Wire-wrapped fuel assembly are widely used in the Generation IV nuclear reactors, including the Sodium-cooled Fast Reactors (SFR) (Chen et al, 2018), the Lead-cooled Fast Reactors (LFR) (Pacio et al, 2018) and the Super Critical Water Cooled Reactors (SCWRs) (Shan et al, 2014). In the wire-wrapped fuel assembly, fuel rods are generally arranged in a hexagonal array, and the coolant flows in gaps around fuel rods, which are termed as the sub-channels.…”