KR100854769B1 - Fixed unit of neclear feul manifold and reactor core the same - Google Patents

Abstract

A stationary unit for securing a fuel assembly and a core device comprising the same are disclosed. The core device for storing a fuel assembly of the present invention includes a reaction vessel having a receiving space, a fixed unit for supporting and fixing a portion of the fuel assembly to penetrate therethrough, and a support positioned at a lower side of the receiving space and coupled with the nuclear fuel assembly. A fixed unit may serve to protect fuel during loading, withdrawal, and reactor operation of the fuel assembly. The fixed unit formed by the lattice structure can increase the density of the core device, which not only reduces the size of the equipment but also increases the service life of the nuclear fuel rod, thereby improving economic efficiency.

Fuel assemblies, fixed units, core devices, gratings

Description

Nuclear fuel assembly stationary unit and core device comprising the same {FIXED UNIT OF NECLEAR FEUL MANIFOLD AND REACTOR CORE THE SAME}

1 is a plan view showing a core in a conventional study.

FIG. 2 is a front view showing, in the study of FIG. 1, a hexagonal flow tube in cross section in the core and a dotted line of the fuel assembly loaded in the flow tube.

3 is a front view showing a nuclear fuel assembly loaded in a core.

4 is a cross-sectional view showing the flow tube of the core in the study.

5 is a plan view showing the core device of the present invention.

6 is a perspective view showing a fixing unit coupled to the core apparatus of the present invention.

7 is an exploded cross-sectional view showing the core device.

8 is a perspective view illustrating a modification of the fixing unit of FIG. 6.

9 is a perspective view illustrating another modification of the fixing unit of FIG. 6.

10 is a plan view showing a model calculated using the concept of a flow tube according to the prior art.

11 is a plan view showing a model calculated using the concept of a fixing unit according to the present invention.

<Description of the symbols for the main parts of the drawings>

90 ： core device 100 ： reaction vessel

200: nuclear fuel assembly 210: nuclear fuel rod

220: bonding board 230: center support rod

240: coupling part 250: heavy box absorber

300: fixed unit 310: guide part

312: lattice hall 314: empty space

320 ： Extension 330 ： Guide Guide

340 ： Circular guide

The present invention relates to a nuclear fuel assembly fixing unit for supporting rod-shaped fuel and a core device including the same, and to a nuclear fuel assembly fixing unit for enhancing the support of nuclear fuel and improving the density of the core.

A nuclear reactor is a device designed to continuously generate and control nuclear fission for use in heat generation, radioactive isotope or plutonium production, generation of strong nuclear radiation, or other useful purposes.

Nuclear fission inside a reactor is a phenomenon in which when a neutron collides with a fissable material, the material collapses, generating two different atoms and generating a large amount of heat. In the process of fission, neutrons are newly generated, and these neutrons can cause other atoms to split in series. In the case of atomic bombs, this chain reaction is not controlled, in the case of nuclear reactors it is very carefully controlled.

Nuclear fission generates a tremendous amount of heat. If one pound of uranium 235 (235U) is fissile, the heat produced is equivalent to burning 1,500 tons of coal. The heat generated is used primarily to generate power. Nuclear fissions usually produce radioactive atoms, which can emit both highly penetrating gamma rays (X-ray radiation) and weak penetrating beta rays (electrons). Thus, reactors are devices that generate heat, neutrons and radiation.

Currently, several nuclear fuel or core models are being developed to achieve high neutron flux in research reactors. The research uses rod-shaped or plate-type fuels, and researches using rod-shaped fuels include TRIGA, HANARO, NRU, and MAPPLE.

The reactor core of Hanaro and MAPPLE consists of rod fuel consisting of hexagonal or circular fuel assemblies. The hexagonal fuel assembly contains 36 fuel rods and the circular fuel assembly contains 18 fuel rods. Hexagonal or circular fuel assemblies generally consist of fuel rods, support structures for supporting them, and fixtures for loading and securing the fuel assemblies to the reactor core. In addition, the research reactor uses hexagonal and circular flow tubes for the protection of fuel assemblies, fuel loading convenience, and the protection of research and experimental devices.The hexagonal fuel assemblies are loaded in hexagonal flow tubes, and the circular fuel assemblies are placed in circular flow tubes. Loaded.

1 is a plan view of a conventional reactor core. As shown therein, the reactor core 10 includes a plurality of hexagonal flow tubes 20a and circular flow tubes 20b in an inner space surrounded by the inner wall 12 of the reflector vessel. On the other hand, the hexagonal fuel assembly 40a is loaded into the hexagonal flow tube 20a in the form shown in FIG. 2, and the circular fuel assembly 40b is also loaded in substantially the same form.

In addition, a neutron absorber 80 (in the form of a control rod or a stationary rod) is disposed around the circular flow tube 20b so as to be movable up and down, and is disposed between the flow tubes 20a and 20b and the fuel assemblies 40a and 40b. Water flows into the space between the flow tubes 20a and 20b and between the flow tubes 20a and 20b and the neutron absorber 80. At this time, the hexagonal flow tube 20a has a thickness of about 1.6mm, the circular flow tube 20b has a thickness of about 1.25mm, and the neutron absorber 80 has a thickness of about 4.5mm.

On the other hand, the flow tubes 20 are spaced apart from each other at predetermined intervals G of several millimeters (mm) so as not to hit each other, and the distance of several millimeters for driving between each of the flow tubes 20a and 20b and the neutron absorber 80 is also provided. Is maintained.

When operating a reactor having such a core 10, heat is generated together with neutrons in the nuclear fuel. To remove this, water is introduced into the lower portion of the reactor core 10 by a cooling pump, and then through the nuclear fuel assemblies 40a and 40b loaded in the flow pipes 20a and 20b inside the core 10. Discharge to the top.

In this case, fluid induced vibration may occur in the fuel assemblies 40a and 40b and the flow tubes 20a and 20b due to the flow of water passing through the insides of the flow tubes 20a and 20b.

On the other hand, the main requirement of the flow tube is that the fuel assembly must be easily loaded and detached from the core, and the horizontal and horizontal behavior of the fuel assembly may be prevented by the flow of water circulating inside the core. The supporting structure of the upper support spring shall be provided. In addition, the locking device should be designed to minimize the vibration of the fuel assembly caused by the flow of water, and should be structurally sound so that there is no possibility of destruction by fatigue or surrender.

To satisfy this condition, the fuel assembly and the flow tube are combined in the form as shown in FIG.

First, referring to Figure 3 looks at the configuration of the hexagonal fuel assembly 40a according to the prior art. 4 will be described with reference to FIGS. 2 and 3 the configuration of the hexagonal flow tube 20a according to the prior art. On the other hand, the configuration of the hexagonal flow tube of Figure 4 is applied substantially the same to the circular flow tube.

The hexagonal fuel assembly 40a of FIG. 3 has a structure in which 36 nuclear fuel rods 70 are bundled around the central support rod 42. Specifically, the nuclear fuel rod 70 is inserted into the lower end and the top end of the bottom end plate (bottom end plate 58) and the top end plate (top end plate 60), respectively, tied together integrally, The center support rod 42 is inserted in the nuclear fuel rods 70 so as to be movable up and down. Protrusions 46 are formed on both sides of the front end 44 of the center support rod 42, and a clasp head 56 is mounted on an upper end of the center support rod 42.

Further, a lower inductor 48 is mounted around the tip 44, and three guide arms 50 extending upward are formed on the outer circumference of the lower inductor 48. Around the central support rod 42 between the lower inductor 48 and the lower end joining plate 58, a lower spring 52 made of, for example, a coil spring is mounted, and the upper end joining plate 60 has an upper support spring 62. ) Is installed.

On the other hand, a plurality (generally three) spacer plates 64 are provided to surround each fuel rod 70 between both ends. These spacers 64 prevent the nuclear fuel rod 70 extending upward and downward from flowing sideways or more.

Referring to FIG. 4, the hexagonal flow tube 20a is inserted into the spider 30, and the spider 30 is coupled to the receptacle 16 at the threaded portion 18. Hexagonal flow tube 20a is fitted into the upper end of the spider 30 as a member drilled up and down. The spider 30 has a groove-like seating portion 32 in which the lower derivative 48 of the hexagonal fuel assembly 40a is seated, and a fastening hole 34 in which the tip 44 of the hexagonal fuel assembly 40a is fastened to the center thereof. ). In addition, a male screw is formed at the lower end of the spider 30 to form a threaded portion 18 by engaging with the female screw of the receptacle 16, and a lock ring that functions as a spring washer is formed at the lower portion of the threaded portion 18. The receptacle 16 is a tubular member that is drilled up and down, and the lower end is fitted to the grid plate 14 and fixed by welding.

2, the hexagonal flow tube 20a accommodates the hexagonal fuel assembly 40a therein and the spider 30 receives the tip 44 of the hexagonal fuel assembly 40a. At this time, the tip 44 of the central support rod 42 of the hexagonal fuel assembly 40a is coupled to the fastening hole 34 of the spider 30. In more detail, the lower spring 52 is compressed by inserting the central support rod tip 44 of the hexagonal fuel assembly 40a into the fastening hole 34 of the spider 30. In this state, when the clasp head 56 of the center support rod 42 is gripped with a tool such as a gripper, and the center support rod 42 is rotated 90 degrees, the projection 46 of the center support rod tip 44 is connected to the fastening hole 34. It is engaged with the lower groove and fixed. This allows water to enter the space inside the hexagonal flow tube 20a and flow up from the bottom through the gap between the nuclear fuel rods 70 to cool the nuclear fuel rods 70.

On the other hand, the upper support spring 62 of the hexagonal fuel assembly 40a is elastically opposed to the upper end of the inner wall of the hexagonal flow tube 20a to provide the hexagonal fuel assembly 40a with a supporting structure against lateral vibration. That is, the upper support spring 62 prevents the upper portion of the hexagonal fuel assembly 40a from being shaken by the fluid induced vibration generated when water flows from the bottom to the inside of the hexagonal flow tube 20a.

In such a configuration, the hexagonal flow tubes 20a are separated from each other at a predetermined interval G so that water flows between them. Moreover, the outer side of the circular flow tube 20b becomes a channel | path in which the neutron absorber 80 moves, and water flows through this channel | path. That is, water flows through the space between the neutron absorber 80 and the inner circular flow tube 20b and through the space between the neutron absorber 80 and the hexagonal flow tube 20a around it.

In this case, there is a disadvantage that the volume of the entire nuclear reactor is increased because there is water between the flow tubes 20a and 20b and the fuel assemblies 40a and 40b as well as between the hexagonal flow tubes 20a. In addition, the water in the core has a cooling function and a deceleration function. The water between the flow tubes plays little role in cooling the heat generated from the nuclear fuel, and absorbs the neutrons, thereby lowering the neutron economy. Moreover, it is disadvantageous to increase the neutron flux, which is the main measure of the reactor's performance.

According to an object of the present invention for solving the above problems, it is possible to reduce the overall size of the equipment by reducing the distance between adjacent flow pipes, and a nuclear fuel assembly fixed unit and a core device including the same can obtain a high neutron flux In providing.

Another object of the present invention is to provide a nuclear fuel assembly holding unit and a core device including the same, which can reduce fluid-induced vibration generated when water passes into the flow tube.

According to a preferred embodiment of the present invention for achieving the above object of the present invention, in the fixing unit for fixing the nuclear fuel assembly for the reactor of the present invention to the core device, the nuclear fuel assembly fixing unit includes a guide and an extension. The guide part has a lattice hole having a lattice structure through which a portion of the fuel assembly passes, and the lattice hole is formed in plural. The extension part extends in one direction from the outside of the guide part to couple the fixing unit to the core device.

As a condition to be provided by the fixed unit, first, the core device should be able to be easily loaded and detached from the nuclear fuel assembly. In addition, it is preferable that an elastic member is provided to prevent horizontal and horizontal behavior of the fuel assembly which may occur due to the flow of water circulating in the core apparatus.

As the fixing unit, each lattice is formed in a hexagonal shape in the lattice structure, at least one of the lattice holes formed on the outer side of the guide portion is formed as a first circular hole, and the remaining lattice holes are hexagonal. It may be formed as a second hole of the shape.

The fixing unit may further include a cylindrical circular guide portion, the circular guide portion may penetrate the first hole. The circular guide portion may be hollow and form a circular hole.

In addition, as another fixing unit, each lattice is formed in a hexagonal shape in the lattice structure, at least any one of the lattice located on the outer side of the guide portion may be omitted to form an empty space. Each of these grids may form a hexagonal grid hole.

On the other hand, the nuclear fuel assembly fixing unit may further comprise a circular guide, the circular guide may be formed in a hollow cylindrical shape. The circular guide may be disposed in the empty space, and the hollow may be formed in a circular shape to accommodate a cylindrical fuel assembly therein.

Further, as another fixing unit, in the lattice structure, each lattice may be formed in a hexagonal shape. That is, all of the gratings are formed in a hexagonal shape, the outer periphery of the guide may be formed in a hexagonal shape. In this case, the lattice hole may be formed in a hexagonal shape, and a portion of the circular guide portion may pass through the hexagonal lattice hole.

The extension part may be formed in plural, and may be formed to extend at the same interval on the outside of the guide part. One end of the extension portion is formed with a fastening portion for coupling a screw, for example, a screw coupling groove or the like is formed can be coupled to the core device.

As a material forming the fixing unit, stainless steel (SUS) may be used.

In addition, in the core device for storing the nuclear fuel assembly for the reactor therein, the core device is a reaction unit having a receiving space, a fixed unit formed with a lattice-type lattice hole through which a portion of the fuel assembly is penetrated and the receiving space Located on the lower side of the may include a support unit coupled to one side of the fuel assembly.

In the lattice structure, each lattice may be formed in a hexagonal shape, at least one of the lattice holes positioned at the outer side of the guide part may be formed as a circular first hole, and the rest may be formed as a hexagonal second hole. .

The core device further includes a circular cylindrical circular guide portion penetrating the first hole, the hollow may be formed in a circular shape, and also a neutron that can be surrounded at regular intervals on the outside of the circular guide portion It may further comprise an absorber.

In the lattice structure, each lattice is formed in a hexagonal shape, and at least one lattice structure is omitted on the circumferential surface to form an empty space, and the lattice hole may be formed in a hexagonal shape.

The core device may further include a hollow cylindrical circular guide portion located in the empty space, and the hollow may be formed in a circular shape.

The core device of the present invention can be used as a core device for research.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments.

FIG. 5 is a plan view showing the core device of the present invention, FIG. 6 is a perspective view showing a fixing unit coupled to the core device of the present invention, and FIG. 7 is an exploded cross-sectional view showing the core device.

As shown in the drawing, the core device 90 for storing the nuclear fuel assembly for a nuclear reactor of the present invention includes a reaction vessel 100, a fuel assembly 200, a fixing unit 300, and a support unit 400. .

The reaction vessel 100 is a case having a receiving space and having a predetermined thickness and is a place where the fuel assembly 200 is stored.

The fuel assembly 200 includes a material capable of nuclear fission, and is loaded into the core device 90 by the fixing unit 300. The fuel assembly 200 includes a hexagonal fuel assembly 200a and a circular fuel assembly 200b. In this embodiment, the hexagonal fuel assembly is described as an example, but the same may be applied to the circular fuel assembly. Hereinafter, the hexagonal fuel assembly will be collectively used as the term fuel assembly.

The fuel assembly 200 includes a nuclear fuel rod 210, a junction plate 220, a central support rod 230, and a coupling part 240.

The nuclear fuel rod 210 is formed of at least one, the hexagonal fuel assembly (200a) may be composed of a set of 36, up to 18 in the circular fuel assembly (200b).

The junction plate 220 is formed on a corresponding side of the upper junction plate 222 and the upper junction plate 222 to insert and fix the upper portion of the nuclear fuel rod 210 and the portion of the nuclear fuel rod 210 It includes a lower bonding plate 224 to partially insert and secure the lower portion. The plurality of nuclear fuel rods 210 may be integrally tied through the junction plate 220.

The center support rod 230 is positioned on the center line that connects the centers of the upper bonding plate 222 and the lower bonding plate 224, and both ends penetrate through the bonding plates 222 and 224. One end 232 of the central support rod 230 penetrating the lower bonding plate 224 may be formed in a conical shape so as to be easily fixed to the support unit 400.

The coupling unit 240 may couple the nuclear fuel assembly 200 to the support unit 400. The coupling part 240 is a protrusion 242 mounted on the one end 232 of the center support rod 230 and the latch head 241 mounted on the other end 234 of the center support rod 230. It includes. In addition, the coupling part 240 extends upwardly from the outer circumferential surface of the support rod derivative 243 and the support rod derivative 243 mounted around the one front end 232 and coupled to the lower bonding plate 224. Dog derivative arms 244.

Meanwhile, a first elastic member 245 such as a coil spring is mounted around the center support rod 230 between the support rod inductor 243 and the lower junction plate 224, and the upper junction plate 222 side The second elastic member 246 may be mounted. The second elastic member 246 provides the fuel assembly 200 with a supporting structure against lateral vibration.

The fixing unit 300 includes a guide part 310 and an extension part 320. The guide part 310 has a lattice hole 312 having a lattice structure, and a portion of the fuel assembly 200 penetrates through the lattice hole 312. In the lattice structure, each lattice is formed in a hexagonal shape. The fixed unit 300 may be positioned above the nuclear fuel assembly 200 to stably set the nuclear fuel assembly 200.

On the other hand, the fixing unit 300 of the lattice hole 312, four of the lattice forming the outer portion of the fixing unit 300 is omitted to form an empty space 314, the empty space 314 is circular The circular guide 340 may be located. The circular guide portion 340 is formed in the same hollow as the guide portion 310 has a circular hole.

A portion of the hexagonal fuel assembly 200a may be accommodated in the lattice hole 312 formed in each of the guide parts 310, and a circular nuclear fuel may be accommodated in the lattice hole 313 formed in the circular guide part 340. The aggregate 200b can be accommodated.

In addition, the circular guide part 340 is surrounded by a neutron absorber 250 at a predetermined distance from the outer surface of the circular guide part 340. The neutron absorber 250 is formed in a hollow shape to accommodate the circular guide portion 340 on the inner side, and may have a thickness of about 4.5 mm.

Here, the neutron absorber 250 may be formed by coating cadmium, hafnium, or the like, which is easy to absorb thermal neutrons for mediating nuclear fuel combustion (nuclear fission reaction), with stainless steel or aluminum. When the neutron absorber 250 thus formed is placed in the core device 90, thermal neutrons are absorbed to lower the reactivity of the furnace.

In the present embodiment, four circular guides 340 are formed, but the present invention is not limited thereto.

The guide part 310 may have a length sufficient to support the second elastic member 246 of the nuclear fuel assembly 200 to the upper bonding plate 222. That is, the fixing unit 300 may accommodate the nuclear fuel assembly 200 to the core device 90 by receiving the second elastic member 246 from the upper bonding plate 222.

In this embodiment, the fixing unit is formed on the upper portion of the nuclear fuel assembly in response to the support unit located on the lower side of the nuclear fuel assembly. Alternatively, the fixing unit may be formed on the lower portion corresponding to the fixing unit located on the upper side. Of course, it is also possible that at least one or more fixing units are formed between the top and the bottom.

The extension part 320 may be formed in plural, and may be formed on the outer side of the guide part 310 at equal intervals. By being formed at the same interval, it is possible to stably fix the fixing unit 300 to the core device 90 to prevent shaking. In addition, a fastening part 322 may be formed at one end of the extension part 320 so as to be coupled to the core device 90, and a screw or a rivet may be used as an example of the fastening part 322. .

The fixing unit 300 may be manufactured using stainless steel (SUS), and may be manufactured using various materials such as Zircaloy-2 and Zircaloy-4.

The support unit 400 is formed at one end of the fuel assembly 200 to stably fix the fuel assembly 200 inside the reaction vessel 100. The support unit 400 includes a spider 410 and a receptacle 420.

The spider 410 is formed with a fastening hole 414 into which one end side of the center support rod 230 is inserted and coupled, and a seating portion 412 for seating the support rod derivative 243 of the fuel assembly 200. Is formed. It is possible to prevent the flow of the nuclear fuel assembly 243 through the spider 410.

The receptacle 420 is a member formed with a hole up and down, is located at the lower end of the spider 410 is coupled by a screw portion 416. The receptacle 420 may be fitted to the grid plate 430 and may be fixed by welding or the like.

8 is a perspective view illustrating a modification of the fixing unit of FIG. 6. As shown therein, the fixing unit 300 is composed of hexagonal grids.

At this time, four lattice holes are formed as a circular first hole 316 among the lattice holes located at the outer side of the fixing unit 300, and the other lattice holes are formed as hexagonal second holes 318. do. A cylindrical circular guide part 340 may pass through the first hole 316. That is, the diameter of the circular guide 340 is smaller than the diameter of the second hole 318. In this case, the neutron absorber may be located in the gap between the first hole 316 and the circular guide 340.

9 is a perspective view illustrating another modification of the fixing unit of FIG. 6.

As shown in the drawing, a guide guide 330 extending downwardly is formed on the lower surface of the guide part 310. The guide guide 330 is formed at the vertices of the gratings, and may be formed at an angle of about 120 degrees at each vertex.

That is, the guide guide 330 serves as a guide when loading the nuclear fuel assembly to the stationary unit 300 to facilitate the loading, and can also support the nuclear fuel assembly on the side, which is effective in preventing fluid-induced vibration. .

10 is a plan view showing a model calculated using the concept of a flow tube according to the prior art, Figure 11 is a plan view showing a model calculated using the concept of a fixing unit according to the present invention.

As shown in the drawing, in order to confirm the advantages of using the fixed unit 300 of the present invention, nuclear calculation is performed using the computer code MCNP.

Let's take a look at the neutron flux that represents the reactor performance and the effective multiplication factor to determine the economics. For comparison, a core with an infinite array of HANARO fuel assemblies is selected. Since the effective length of the nuclear fuel assembly is 70 cm, the axial height in nuclear calculations is limited to 120 cm. Since the core is infinitely arranged, there is no neutron leakage in the transverse direction, but there is leakage in the axial direction.

In the conventional invention and the present invention, since the same fuel assembly is used, the inner space P1 of the flow pipe 20a and the guide 310 has the same volume. The flow pipe 20a of the related art requires the space P2 of the flow pipe 20a and the additional coolant, whereas the guide portion 310 of the present invention does not need a space.

On the other hand, when the output of each fuel assembly is set to 1.15MW, the results of comparing the conventional flow pipe and the guide of the present invention are shown in Table 1.

In the case of using the guide portion 310, the distance between the fuel assemblies is reduced to about the same thickness as the conventional flow tube 20a, so that the cross-sectional area is reduced by about 10.0%. That is, the space corresponding to the thickness of the water passage (P2) and one of the flow pipe (20a) of Figure 10 is removed. As a result, the effective multiplication factor is turned on, it can be seen that the neutron absorption is reduced. In addition, the reactivity value comparing the effective multiplication factor for the two cores increased by about 7.6 mk. In addition, the effective multiplication factor is increased, allowing for longer cycle lengths, thus reducing the consumption of the required fuel assembly. On the other hand, the neutron flux compared the total neutron flux of the highest region in the center of the fuel assembly, it can be seen that the neutron flux of the present invention increased to about 5.0%.

As described above, according to the present invention, the density of the core compared to the core by the study of rod-type fuel using a conventional flow tube using a fixed unit having a plurality of holes having a lattice structure for accommodating a plurality of hexagonal fuel assemblies, respectively. In addition, it is possible to increase the core performance, and to increase the core multiplication factor, thereby reducing the consumption of the fuel assembly, thereby improving the core economy.

In addition, the density of the core can be increased by minimizing the space between the fixed unit and the neutron absorber, thereby improving performance and economy.

In addition, the fuel assembly is coupled to the core device at the same time to support the fuel assembly has the effect of maintaining a stable state without shaking the fuel assembly in the inflow of water.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (22)

A fixed unit for fixing a nuclear fuel assembly for a reactor to a core device, A guide part having a plurality of lattice holes having a lattice structure through which a portion of the nuclear fuel assembly passes; And An extension part which extends in one direction from the outside of the guide part and engages with the core device; Nuclear fuel assembly fixed unit comprising a. The method of claim 1, In the lattice structure, each lattice is formed in a hexagonal shape, at least one of the lattice holes positioned at the outer side of the guide part is formed as a circular first hole, and the rest are formed as hexagonal second holes. A nuclear fuel assembly fixed unit. The method of claim 2, And a hollow cylindrical circular guide portion penetrating through the first hole, wherein the hollow has a circular shape. The method of claim 1, In the lattice structure, each lattice is formed in a hexagonal shape, at least any one of the lattice located on the outer side of the guide portion is omitted to form an empty space of the nuclear fuel assembly fixed unit. The method of claim 4, wherein The grid hole is a nuclear fuel assembly fixed unit, characterized in that formed in a hexagonal shape. The method of claim 4, wherein And a hollow cylindrical circular guide disposed in the empty space, wherein the hollow has a circular shape. The method of claim 1, In the lattice structure, all grids are formed in a hexagon, and the grid hole is a nuclear fuel assembly fixing unit, characterized in that formed in a hexagonal shape. The method of claim 1, The stationary unit is a nuclear fuel assembly fixed unit, characterized in that formed of stainless steel (SUS). The method of claim 1, The fuel assembly fixing unit, characterized in that the plurality of extension is formed, extending at the same interval on the outside of the guide. In the core device for storing the nuclear fuel assembly for the reactor therein, A reaction vessel having a receiving space; A fixed unit having a lattice hole having a lattice structure through which a part of the nuclear fuel assembly penetrates; And A support unit positioned at a lower side of the accommodation space to which one side of the nuclear fuel assembly is coupled; Core device comprising a. The method of claim 10, And the stationary unit is located above the fuel assembly. The method of claim 10, The fixing unit A guide part having the lattice hole through which a portion of the fuel assembly passes; And An extension part which extends in one direction from the outside of the guide part and engages with the core device; Core device comprising a. The method of claim 12, In the lattice structure, each lattice is formed in a hexagonal shape, at least one of the lattice holes positioned at the outer side of the guide part is formed as a circular first hole, and the rest are formed as hexagonal second holes. Core device. The method of claim 13, And a hollow cylindrical circular guide portion penetrating the first hole, wherein the hollow is circular in shape. The method of claim 14, And a neutron absorber, wherein the neutron absorber surrounds the outer side of the circular guide portion at regular intervals. The method of claim 12, Each lattice in the lattice structure is formed in a hexagonal shape, the core device on the circumferential surface characterized in that at least one or more lattice structure is omitted to form an empty space. The method of claim 16, The lattice hole is a core device, characterized in that formed in a hexagonal shape. The method of claim 16, And a hollow cylindrical circular guide portion positioned in the empty space, wherein the hollow is circular in shape. The method of claim 10, The fixing unit A guide part having a plurality of lattice holes having a lattice structure through which a portion of the nuclear fuel assembly passes; And An extension part which extends in one direction from the outside of the guide part and engages with the core device; To include, wherein the extension is formed in plurality, the core device, characterized in that formed extending at the same interval on the outside of the guide. The method of claim 10, The fuel assembly is At least one nuclear fuel rod; A bonding plate mounted to the lattice hole and having both ends of the nuclear fuel rods coupled thereto; A center supporting rod disposed on a center line of the bonding plate and having both ends penetrating through the bonding plate; And A coupling part formed at one end of the nuclear fuel rod and coupled to the support unit; Core device comprising a. The method of claim 20, The support unit One end of the central support rod is inserted and coupled to prevent the flow of the nuclear fuel assembly; And A receptacle positioned below the spider and screwed with the spider; Core device comprising a. The method of claim 10, The fixed unit includes a guide portion in which a plurality of lattice holes having a lattice structure through which a portion of the fuel assembly passes is formed, wherein the guide portion further includes a plurality of guide guides extending downward, and the guide guide portion includes the fuel assembly. Core device, characterized in that for supporting the side.

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