Spacers for a fuel assembly

Purpose: To reduce the fluid pressure loss and enable highly efficient cooling. Constitution: Among two types of spacers, one of the types is constituted as a spacer of small and reduced weight having a flexible structure mainly for the purpose of preventing fine vibrations of fuel rods, etc. during usual operation, while the other of the types is constituted as a spacer of somewhat rigid structure and large strength mainly for the purpose of sufficiently suppressing the behaviors of the fuel assembly upon accidental abnormality such as earthquakes. Then, these two kinds of spacers are properly arranged longitudinally to the fuel rods. Modified lattice type spacers having protrusions disposed on each side, combined structure of cylindrical rings, etc. are used as the spacers for abnormal loads. Further, wires fabricated and deformed into an appropriate shape and resiliently supported are used as the spacers working during normal operation. (Horiuchi, T.)