CFD analysis of mixing behavior in multi-layer SCWR fuel assembly

A multilayer fuel assembly is proposed by Cheng with the main purpose to reduce the hot channel factor in SCWR. A homogeneous turbulent mixing of coolant flows with different temperatures in mixing layers is crucial to minimize the maximum fluid temperature and the maximum cladding temperature in the multilayer fuel assembly. In the present study, the mixing behaviors of several mixing layer structures have been investigated using CFD code CFX5.6. The uniformities of temperature and mass flux distributions at the outlet of mixing layer are evaluated. Even though results cannot yet be considered to be final, they already indicate the direction for further design optimization of mixing layer. (author)