Fuel assembly for pwr nuclear reactor

Abstract

Provided is a fuel assemblyfor a PWR nuclear reactor capable of stably creating transverse flows of coolant for pressing and securing control rods so as to restrain vibration of the control rods in order to restrain the outer surfaces of the control rods and the inner surfaces of control rod guide tubes from being worn, wherein an upper nozzle arranged above the fuel assembly comprises an adapter plateconstituting the lower structure of the upper nozzle, a side wall extended along the periphery of the adapter plate, an overhang projected into a space above the adapter plate from the upper part of the side wall, and apertures for attaching control guide tubes and passage holes, which are formed in the passage surface of the adapter plate, and wherein thoseA,B,C of the passage holes which are located at positions where the coolant impinges upon the overhang are generally arranged, line-symmetric with respect to diagonal lines of the passage surface serving as symmetric axes Q, and ligamentsaround the passage holes located inside and outside of thoseof the attaching apertures which are located on the outer peripheral side are set to be larger than ligamentsaround the passage holes which are located on opposite transverse sides of those of the attaching apertures.