Fuel assembly and fuel spacer

A fuel assembly having fuel rods inserted into hollow cylindrical cells welded to one another in a grating arrangement so as to form a spacer which keeps the fuel rods correctly spaced from one another, the spacer having spacer elements disposed in a plurality of stages in the longitudinal direction of the fuel rods, said fuel assembly, comprising:

• thin-walled cylinders extending in the longitudinal direction of said fuel rods and being fixed to said cells at least at positions within the spaces between adjacent fuel rods which correspond to the uppermost of said stages of said spacer elements, each of said cylinders having vanes provided therein, said vanes obliquely projecting inward of said cylinders and allowing a coolant flowing through said spaces and forming two-phase flows to generate swirling flows toward said fuel rods and enabling adherence of a liquid film on said fuel rods.

A fuel assembly having fuel rods inserted into hollow cylindrical cells welded to one another in a grating arrangement so as to form a spacer which keeps the fuel rods correctly spaced from one another, the spacer having spacer elements disposed in a plurality of stages in the longitudinal direction of the fuel rods, said fuel assembly comprising:

• spiral vanes fixed to said cells at least at positions within the spaces between adjacent fuel rods which correspond to the uppermost of said spacer elements, said vanes allowing a coolent flowing through said spaces and forming two-phase flows to generate swirling flows toward said fuel rods and enabling adherence of a liquid film on said fuel rods.

A fuel spacer for keeping fuel rods correctly spaced from one another, the spacer comprising a plurality of hollow cylindrical cells welded to one another in a grating arrangement into which the fuel rods are inserted, said fuel;

• spacer comprising:
• vanes formed on said cells, each vane being bent from a cut formed in a part of the side wall of the cell, said vanes obliquely projecting into the corresponding spaces between adjacent fuel rods and allowing a coolant flowing through said spaces and forming two-phase flows to generate swirling flows toward said fuel rods and enabling adherence of a liquid film on said fuel rods.

A fuel spacer for keeping fuel rods correctly spaced from one another, the spacer comprising a plurality of hollow cylindrical cells welded to one another in a grating arrangement into which the fuel rods are inserted, said fuel spacer comprising:

• thin-walled cylinders extending in the longitudinal direction of said fuel rods and being fixed to said cells at positions within the spaces between adjacent fuel rods, each of said cylinders having vanes provided therein, said vanes obliquely projecting inward of said cylinders and allowing a coolant flowing through said spaces and forming two-phase flows to generate swirling flows toward said fuel rods and enabling adherence of a liquid film on said fuel rods.

A fuel spacer for keeping fuel rods correctly spaced from one another, the spacer comprising a plurality of hollow cylindrical cells welded to one another in a grating arrangement into which the fuel rods are inserted, and spacer elements disposed in a plurality of stages in the longitudinal direction of the fuel rods, said fuel spacer comprising:

• spiral vanes fixed to said cells at positions within the spaces between adjacent fuel rods, said vanes allowing a coolant flowing through said spaces and forming two-phase flows to generate swirling flows toward said fuel rods and enabling adherence of a liquid film on said fuel rods.