Patent ID: 8406369
Filing Date: 2013-03-26
Classification: G21C,Y02E

Abstract:
1. A fuel assembly for a PWR nuclear reactor wherein an upper nozzle arranged above the fuel assembly comprises: an adapter plate constituting a lower structure of the upper nozzle, and being formed in a square shape whose two diagonal lines orthogonal to each other pass through a center and diagonal corners of a passage surface of the adapter plate; a plurality of upright side walls extended in an upright direction along sides of the periphery of the adapter plate; an overhang projected into a center area of a space above the adapter plate from the upper part of the side wall; and apertures for attaching control rod guide tubes and passage holes, which are formed in a passage surface of the adapter plate, wherein the passage holes in the passage surface of the adapter plate include: one or more of first passage holes located on an area where coolant impinges upon the overhang, the first passage holes being generally arranged line-symmetric with respect to one diagonal line of said two diagonal lines serving as a symmetric axis, and second passages holes which are not at least partially covered by the overhang, and wherein first ligaments around the first passage holes which are completely covered by the overhang projected from the side walls and are located on an outer side of those of the attaching apertures which are located on the outer peripheral side of the passage surface, are set to be larger than second ligaments around the second passage holes located on opposite transverse sides of those of the attaching apertures, further wherein one or more elongated holes constituting the first passage holes are extended such that a longitudinal direction of the one or more elongated holes extends in parallel to the corresponding side wall located in areas that are line-symmetrical with respect to the one diagonal line.