Bottom nozzle of nuclear fuel assembly provided with flow holes by utilizing layered aircraft airfoil structure

Abstract

Embodiments of a bottom nozzle of a nuclear fuel assembly provided with flow holes by utilizing a layered aircraft airfoil structure are provided. The bottom nozzle not only increases efficiency of filtering foreign substances by minimizing a size of the flow holes by constituting a shape of flow holes into cross stripes but also prevents coolant water flow velocity drop through prevention of coolant water pressure drop by constituting a lateral sectional shape of the grid frames constituting the cross stripes into an aircraft airfoil type.

Claims

1. A bottom nozzle of a nuclear fuel assembly provided with flow holes, the bottom nozzle of the nuclear fuel assembly comprising: a plurality of flow holes formed in a shape of cross stripes, wherein a plurality of grid frames constituting the cross stripes are stacked while crossing the flow holes, thereby minimizing the size of the flow holes, wherein the grid frames are constructed by stacking first grid frames and second grid frames, and a lateral sectional shape of the grid frames is provided to be curved to expand from a tapered form in the direction coolant water flows in and then to return to being tapered again by becoming pointy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objectives, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a view showing a typical nuclear fuel assembly;

(3) FIG. 2A is a perspective view showing a bottom nozzle of the nuclear fuel assembly according to a conventional art;

(4) FIG. 2B is a plan view showing the bottom nozzle of the nuclear fuel assembly according to the conventional art;

(5) FIG. 3 is a plan view showing a bottom nozzle of a nuclear fuel assembly provided with flow holes by utilizing a layered aircraft airfoil structure according to an exemplary embodiment of the present invention;

(6) FIG. 4 is a perspective view showing a main portion of the bottom nozzle of the nuclear fuel assembly provided with flow holes by utilizing the layered aircraft airfoil structure according to the exemplary embodiment of the present invention;

(7) FIG. 5 is a bottom perspective view showing the main portion of the bottom nozzle of the nuclear fuel assembly provided with flow holes by utilizing the layered aircraft airfoil structure according to the exemplary embodiment of the present invention;

(8) FIG. 6 is a bottom view showing the bottom nozzle of the nuclear fuel assembly provided with flow holes by utilizing the layered aircraft airfoil structure according to the exemplary embodiment of the present invention; and

(9) FIG. 7 is a sectional view showing the main portion of the bottom nozzle of the nuclear fuel assembly provided with flow holes by utilizing the layered aircraft airfoil structure according to the exemplary embodiment of the present invention;

DETAILED DESCRIPTION

(10) Terms or words used in the present specification and claims are not to be construed as being limited to usual or dictionary meanings thereof. Based on a principle that the inventors may properly define the concept of terms in order to best explain invention thereof in the best way possible, the terms or words should be interpreted as having a meaning and concept corresponding to the technical idea of the present invention.

(11) Hereinbelow, a bottom nozzle of a nuclear fuel assembly provided with flow holes by utilizing a layered aircraft airfoil structure (hereinafter, referred to as “bottom nozzle”) according to exemplary embodiments of the present invention will be described in detail with reference to the accompanying FIGS. 3 to 7. Throughout the drawings, the same reference numerals will refer to the same or like parts.

(12) The bottom nozzle 100 minimizes a size of flow holes 200, thereby increasing efficiency of filtering foreign substances and also ensures a smooth flow of coolant water by preventing coolant water pressure from being dropped when the coolant water flow passes through the flow holes.

(13) Therefore, both of the coolant water flow and the efficiency of filtering foreign substances may be increased.

(14) The bottom nozzle 100 is provided with the flow holes 200 through which the coolant water flows therein.

(15) In this case, the flow holes 200 are provided in a shape of cross stripes as shown in FIG. 3.

(16) That is, grid frames 300 are provided in the shape of cross stripes on a flow plate, thereby providing flow holes 200 each in a shape of a square.

(17) As such, as the flow holes 200 are provided in the shape of cross stripes, the size of the flow holes 200 through which the coolant water passes may be minimized by increasing thickness of the grid frames 300, and the efficiency of filtering the foreign substances may be maximized accordingly.

(18) On the other hand, the grid frames 300 providing the flow holes 200 are constructed by being stacked in a height direction of the bottom nozzle 100.

(19) In this case, the grid frames 300 are installed crossing the flow holes 200 while being stacked.

(20) By such a constitution, the flow holes 200 are constituted by being divided by a cross shape through the grid frames 300 neighboring in a height direction as shown in FIGS. 3 to 7.

(21) By constructing the grid frames 300 stacked as described above to cross each other, the size of the flow holes 200 may be minimized, thereby increasing the efficiency of filtering the foreign substances.

(22) The pressure drop of the coolant water is also to be taken into consideration as the grid frames 300 are stacked in a plurality of layers, so the grid frames 300 may be composed of two layers.

(23) In this case, for convenience of description, the grid frame 300 installed on the uppermost of the bottom nozzle 100 is referred to as a first grid frame 310, and the grid frame 300 installed under the first grid frame 310 is referred to as a second grid frame 320.

(24) On the other hand, the flow holes 200 need to not only maximize the efficiency of filtering the foreign substances but also prevent the pressure drop when the coolant water flows through the flow holes 200, so the grid frames 300 providing the flow holes 200 is formed in a streamlined shape of an aircraft airfoil.

(25) More precisely, as shown in FIGS. 4 and 7, the lateral sectional shape of the grid frames 300 is provided in a shape of an aircraft airfoil, wherein the lateral sectional shape is curved to expand from a direction coolant water flows in and then to become pointy by being tapered again.

(26) That is, even when the bottom nozzle 100 is provided to have a small size of the flow holes 200 due to the construction in the shape of the cross stripes, with the grid frames 300 as references, the coolant water flows from each of both sides when passing through the flow holes 200, and is then guided along the curved shape of the grid frames 300. Subsequently, the coolant water merged at a pointy portion of the grid frames 300 flows toward the fuel rods, so a phenomenon in which the pressure drops when the coolant water flows into a fuel rod region does not occur.

(27) Accordingly, as the coolant water flows smoothly through the flow holes 200 without having a reduction of the flow velocity, both efficiency of preventing cooling water pressure drop and the efficiency of filtering foreign substances may be increased.

(28) The flow holes 200 configured as described above may be minimized due to the stacked configuration of the first grid frames 310 and the second grid frames 320.

(29) In addition, the lateral sectional shape of the grid frames 300 constituting a shape of the cross stripes is provided in a streamlined one in a direction where the coolant water flows, thereby preventing the pressure from dropping when the coolant water flows in.

(30) Due to such a configuration, as shown in FIG. 7, the coolant water flowing in through the flow holes 200 flows along the curved portion of the grid frames 300, merges at the pointy portion of the grid frames 300, and then flows out toward the fuel rods. In this case, the pressure drop is prevented in the same way as air flow at the aircraft airfoil passes without a pressure drop, whereby the coolant water flow velocity is not reduced. Accordingly, the efficiency of filtering the foreign substances may be maximized due to a configuration of the compact flow holes 200.

(31) As described above, the bottom nozzle of the nuclear fuel assembly provided with flow holes by utilizing a layered aircraft airfoil structure constitutes the flow holes in the shape of cross stripes, wherein the grid frames are constructed by being stacked and crossing one another, and the lateral sectional shape of the grid frames is applied with an aircraft airfoil shape.

(32) Accordingly, it is possible to maximize the efficiency of filtering the foreign substances while maintaining the coolant water flow velocity as it is.

(33) Although the present invention has been described in detail with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and variations are within the scope of the appended claims.