Fuel assembly

When the power of a fuel assembly reaches a limit power, in other words, when the flow of coolant liquid membranes flowing on the surface of a fuel rod are dissipated, a great amount of liquid droplets are contained in the steam flow, but the liquid droplets are not used effectively for cooling the fuel rod. As a result, the reactor power undergoes operation limit having margin in the limit power. In the present invention, a spacer is constituted by a substantially circular cell with protrusions and the upper end of the spacer is bent to the side of the fuel rod. Accordingly, the liquid droplets passing through the fuel rod spacer are blown to the surface of the fuel rod due to the bent portion formed to the cell. Then, liquid membranes are formed on the surface to prevent the burning damage of the fuel rod, thereby capable of increasing the reactor power, to provide a more safe reactor. (N.H.)