KR101961458B1 - Spent nuclear fuel dry storage cask - Google Patents

Abstract

A spent fuel dry storage vessel for a light-water reactor, wherein the spent fuel is stored, wherein the spent fuel is stored and the cooling efficiency of the spent fuel is enhanced and the criticality is excellent, wherein a cask and spent fuel assemblies constituting the outer case are stored, A cooling unit installed on each of the baskets for absorbing and removing residual heat of the spent nuclear fuel, and a cooling unit installed on the lid, And a heat dissipating unit connected to the cooling unit to dissipate the heat conducted from the cooling unit to the outside.

Description

{SPENT NUCLEAR FUEL DRY STORAGE CASK}

The present invention relates to a spent fuel dry storage vessel for a light water reactor.

Generally, nuclear fuel (hereinafter referred to as 'spent fuel') used for nuclear power generation in Light Water Reactor is stored in a storage place in a specially designed storage container before final disposal.

The method of storing spent fuel is divided into wet storage method and dry storage method. In recent years, dry storage methods, which are advantageous in terms of capacity expansion and long-term management, have been mainly employed. Dry storage of spent fuel has advantages such as excellent stability, low operating cost, storage capacity increase and excellent expandability compared with wet storage method.

In the dry storage method, a plurality of baskets loaded with spent fuel assemblies are accommodated and stored in a cask, which is a metal container.

Spent fuel generates large amounts of thermal neutrons. Therefore, dry storage containers require better cooling efficiency and criticality control so that spent fuel can be stably stored for a long period of time.

Accordingly, it is possible to provide a spent fuel storage vessel for a light-water reactor, which is excellent in cooling efficiency for spent nuclear fuel and in controlling criticality.

The present invention also provides a spent fuel storage vessel for a light-water reactor, which can reduce the residual heat generated inside the storage vessel and reduce the internal temperature of the storage vessel.

The present invention also provides a spent fuel storage vessel for a light-water reactor capable of reducing deterioration of high temperature and corrosion of a storage vessel structural member.

The storage container of the present embodiment is a dry fuel storage container for a light-water reactor, which stores spent nuclear fuel, wherein a cask constituting an outer case, a spent fuel assembly and a plurality of baskets arranged in the cask, A cooling unit installed in each of the bases and absorbing residual heat of the spent nuclear fuel and connected to the cooling unit, the cooling unit being installed in the open top of the cask to seal the cask, And a heat dissipation unit that dissipates the heat conducted in the heat dissipation unit.

The cask may further include spacers spaced apart from each other in the axial direction to maintain a position and an interval of the baskets.

And a shock absorbing material positioned at the lower end of the cask.

The cooling unit may include a plurality of heat pipes extending through the central portion along the direction of the basket axis and absorbing residual heat of the basket and conducting the heat to the heat dissipation unit.

The heat pipe may be installed at a measuring pipe or a guide pipe of the spent nuclear fuel assemblies accommodated in the basket.

And a neutron absorber provided inside the heat pipe to absorb neutrons.

The heat dissipating unit may have a tubular structure in which the lead has a space sealed therein, and the heat pipe may communicate with the inner space of the reed, and a working fluid may flow into the inner space of the reed to conduct heat.

The heat pipe may be a structure that is separated from the inner circumferential surface and is provided with a bell having a hole formed on its surface to separate a working fluid in a liquid state from a working fluid in a vapor state.

The lid may include a plurality of bolts installed along the outer periphery and fastened to the upper end of the cask to seal the top of the cask.

According to this embodiment, it is possible to enhance the cooling performance and the criticality control effect of the spent nuclear fuel loaded in the dry storage container for the light water reactor through the neutron absorber and the coolant.

Thus, the residual heat generated from the spent nuclear fuel can be effectively removed without supplying external power, and the long-term integrity can be secured by reducing the deterioration of the high temperature of the storage container and the corrosion phenomenon during storage for 20 years or more.

Also, by controlling the criticality through the neutron absorber, it is possible to prevent re-critical accidents that may occur during the spent fuel storage period, to improve the safety of the dry storage container, and to reduce the risk of radioactive material and radiation leakage.

In addition, since the cooling performance is improved and the criticality control is effectively performed, a larger amount of spent fuel can be efficiently stored in a narrow space in the storage container, and a safe and quick capacity expansion effect can be expected without building additional facilities.

In addition, it becomes possible to provide a dry storage container for light water reactors that can be independently installed in the plant, having sufficient cooling performance and criticality control performance.

1 is a schematic view showing the construction of a spent fuel dry storage container for a light-water reactor according to the present embodiment.
FIG. 2 is a view showing in detail a part of the structure of a spent fuel dry storage vessel for a light-water reactor according to the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Wherever possible, the same or similar parts are denoted using the same reference numerals in the drawings.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

All terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

FIG. 1 shows a spent fuel dry storage vessel for a light-water reactor according to an embodiment of the present invention, and FIG. 2 shows a detailed structure of the thermal storage vessel.

1, the spent nuclear fuel storage vessel 100 for a light-water reactor according to the present embodiment includes a cask 10 and spent nuclear fuel assemblies 20 as an outer casing, A plurality of baskets 30 arranged in the cask and arranged on the cask, a lid 40 installed on the open top of the cask to seal the cask, And a heat dissipating unit 60 installed on the lead and connected to the cooling unit to dissipate the heat conducted from the cooling unit to the outside.

The cooling unit 50 is connected to the lid 40 to conduct the heat absorbed by the basket 30 to the lid 40. The lid 40 is connected to the outside air, .

Thus, the spent fuel aggregate residual heat in the basket 30 is quickly transferred to the lid 40 through the cooling portion 50 and is radiated to the outside through the large-area lid 40, thereby improving the residual heat removal efficiency The cooling performance of the storage container 100 can be improved.

Hereinafter, each of the components will be described in more detail. The cask 10 has a space in which the basket 30 is accommodated, and forms an outer case of the storage container. The cask 10 may have a cylindrical shape, and the shape of the cask 10 may be variously modified. In the present embodiment, the cask 10 may be formed of a metal material. The cask 10 surrounds the basket 30 in which the spent nuclear fuel assemblies 20 are accommodated and shields heat and radiation generated from the spent nuclear fuel assemblies inside the baskets 30.

A shock absorbing material 12 for absorbing and absorbing a shock applied to the cask 10 may be installed at the lower end of the cask 10. [ A plurality of baskets (30) are supported in the cask (10), and spacers (14) for maintaining the positions and spacing are provided. As shown in FIG. 1, the spacers 14 are provided on the inner circumferential surface of the cask 10, and a plurality of spacers 14 are disposed along the axial direction of the cask 10. The spacer 14 has a plate structure, and the outer end of the spacer 14 is in contact with the inner circumferential surface of the cask 10 and the inner end of the spacer 14 is in contact with the outer surface of the arranged basket 30 to prevent the basket 30 from flowing.

The basket (30) has a structure extending along the axial direction of the cask (10) and having a receiving space therein. The spent fuel assemblies 20 are stored in the inner space of the basket 30. A plurality of baskets (30) are arranged and loaded in the cask (10). The plurality of baskets (30) are supported by the spacers (14) provided on the inner peripheral surface of the cask (10) to maintain their arrangement.

The spent nuclear fuel assemblies 20 stored in the basket 30 are provided with measuring tubes or guide tubes. The heat pipe 52 of the cooling unit 50 may be installed in the measurement tube or guide pipe of the spent nuclear fuel assembly 20 in the axial direction.

 The measuring tube and the guide tube are empty tubes. When nuclear fuel assemblies are loaded inside the reactor, a number of instruments are located through the measuring tubes to measure the reactor information. Further, the control rod is moved to the upper and lower positions through the guide pipe to control the reactivity and the reactor output. Therefore, the measurement tube or the guide tube of the nuclear fuel assembly can be understood as an empty channel in which the fuel rod is not located in the nuclear fuel assembly.

As described above, since the heat pipe is located inside the spent nuclear fuel assemblies through the measuring tube and the guide tube, it is possible to effectively absorb and remove the residual heat of the spent nuclear fuel in the basket.

The upper end of the cask 10 is opened to allow the basket 30 to be loaded therein. A lead 40 is provided at the opened upper end of the cask 10 to seal the inside of the cask 10. The lead 40 is mounted with a plurality of bolts 42 for assembly with the cask 10 along the outer periphery. Therefore, it is possible to seal the open top of the cask with the lead by installing the lead on the top of the cask and tightening the bolt. The bolt 42 is extended so as to pass through the inner space of the lid and is fastened to the upper end of the cask.

In the present embodiment, the lead 40 has a structure that quickly dissipates the heat conducted by the cooling unit 50 to the outside. To this end, the lead 40 has a heat dissipating portion 60 for dissipating heat to the outside more effectively. The structure of the heat dissipating portion 60 will be described later.

The lid 40 is connected to the basket 30 via the cooling unit 50 on the basket 30. The heat generated in each basket 30 is absorbed through the cooling unit 50 and is quickly transmitted to the lid 40 and is radiated to the outside through the heat dissipation unit 60 of the lid 40.

The cooling unit 50 extends through the central portion along the axial direction of the basket 30 and absorbs residual heat of the respective baskets 30 so as to be connected to the heat dissipation unit 60 of the lid 40 And may include a plurality of heat pipes 52 that conduct.

The heat pipes 52 are arranged in the same manner as the arrangement of the baskets 30 arranged in the cask 10 and are connected to the respective baskets 30. The heat pipe 52 may be installed at a measuring pipe or a guide pipe of the spent nuclear fuel assembly 20 accommodated in the basket 30. The heat pipes 52 provided on the respective baskets 30 are connected to the leads 40 on the upper side of the cask 10. The heat absorbed in the heat pipe 52 is transferred to the upper portion of the lead 40 and is quickly dissipated to the outside through the heat dissipating portion 60 provided in the lead 40. [

The heat pipe 52 functions as a heat pipe that absorbs the heat of the basket 30 and quickly transfers the heat to the lid 40. The residual heat emitted from the spent nuclear fuel assemblies 20 stored in the basket 30 is conducted and removed to the lid 40 through the respective heat pipes provided in the basket 30. [

The heat pipe 52 is a tubular structure in which a working fluid such as Freon, water, or sodium metal is accommodated. The working fluid is phase-changed into liquid and vapor, and the heat is transferred at a high speed. Since the structure and function of the heat pipe have already been disclosed, many detailed descriptions are omitted here.

Thus, the working fluid contained in the heat pipe 52 is heated while absorbing the residual heat of the spent nuclear fuel assembly 20 accommodated in the basket 30, and the heated working fluid is phase-changed into the vapor state, So that heat is transferred to the lid 40. The working fluid in the vapor state moved to the upper portion of the heat pipe 52 is condensed while being discharged, and the condensed liquid is moved down to the basket 30 where the residual heat is generated by the gravity. The heat pipe 52 absorbs the residual heat generated in the basket 30 and cools it while repeating such a cycle.

The heat pipe 52 penetrates the center of the basket 30 so that the residual heat of the spent nuclear fuel assemblies 20 stored in the basket 30 is conducted to the heat pipe 52 and can be effectively removed. Each of the heat pipes 52 extends upward and is connected to the lower end of the lid 40 disposed above the basket 30.

The heat pipe 52 is provided with a neutron absorber 54 therein. The neutron absorber 54 may be a material having a large cross-sectional area of neutron absorption reaction, for example, the neutron absorber 54 may be a boron compound. The neutron absorber 54 absorbs neutrons emitted from the spent nuclear fuel assemblies 20 stored in the basket 30 at a high rate to lower the criticality. As described above, since the neutron absorber 54 is embedded in the central heat pipe 52, the degree of criticality can be effectively controlled along with the removal of the internal residual heat of the basket 30.

The heat dissipating unit 60 has a tubular structure having a space 62 in which the lid 40 is hermetically sealed and the heat pipe 52 communicates with the inner space of the lid 40 And a working fluid flows into the inner space of the lead 40 to conduct heat.

Accordingly, the heat exchange efficiency with the cooling section 50 is increased, and the heat transferred from the cooling section 50 can be dissipated to the outside more quickly. The lead 40 may be made of a material having a high thermal conductivity.

2, in the present embodiment, the lead 40 has a structure in which the interior has an empty sealed space 62, and the heat pipe 52 is formed in the inner space 62 ). The inner space 62 of the lead 40 constituting the heat dissipating portion can be connected to the heat pipe 52 in a vacuum state, for example.

Accordingly, the working fluid in the vapor state, which is moved upward by the heat absorption of the heat pipe 52, flows into the internal space 62 of the lead 40 communicating with the upper end of the heat pipe 52. Accordingly, the working fluid in the vapor state contacts the entire surface of the lead 40 in the inner space of the lid 40 to perform heat exchange.

That is, the heat conducted to the upper portion of the heat pipe 52 is rapidly transferred to the lid 40 through the heat exchange between the lid 40 and the working fluid having a relatively large area as compared with the heat pipe 52. The heat transmitted to the lid 40 is dissipated to the outside through the front surface of the lid 40 in contact with the outside air. The working fluid condensed while exchanging heat with the lid 40 goes down again through the heat pipe 52 to absorb the residual heat in the basket 30. [

By performing the heat exchange between the lid 40 and the working fluid of the heat pipe 52 through the structure of the heat radiating portion 60 in which the lead 40 having the internal space communicates with the heat pipe 52, It is possible to maximize the internal residual heat removal efficiency.

The cooling unit 50 according to the present embodiment may further include a baffle 56 installed inside the heat pipe 52. The baffle 56 is a tube structure that is spaced apart from the inner circumferential surface of the heat pipe 52 and has a hole 58 formed on the surface thereof to divide the flow path between the working fluid in the liquid state and the working fluid in the vapor state inside the heat pipe 52 . The baffle 56 protrudes from the center of the heat pipe 52 to the inner space 62 of the lid 40. The working fluid in the vapor state is discharged through the holes 58 formed in the baffle 56 and flows into the inner space of the lid 40. [

As described above, the flow path of the phase-changed working fluid in the heat pipe 52 is divided by the baffle 56 so that the up-and-down movement becomes more smooth, thereby further enhancing the heat transfer effect. Further, by providing the baffle (56), it is possible to clearly distinguish the flow path of the working fluid in the heat pipe (52) irrespective of the diameter of the heat pipe (52). Therefore, it is possible to secure the heat transfer area and increase the residual heat removal efficiency through the design of the heat pipes 52 of various sizes.

While the illustrative embodiments of the present invention have been shown and described, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

10: Cask 20: Spent fuel assembly
30: Basket 40: Lead
42: bolt 50: cooling part
52: heat pipe 54: neutron absorber
56: Baffle 58: Hole
60: heat sink 62: space

Claims (9)

A spent fuel storage vessel for a light-water reactor for storing spent fuel,
A plurality of baskets for storing cask and spent fuel assemblies constituting the outer case and arranged and disposed in the cask, a plurality of baskets installed at the open upper end of the cask to seal the cask, A cooling unit installed in each of the baskets for absorbing and removing residual heat of the spent nuclear fuel and a heat dissipation unit installed in the reed and connected to the cooling unit to dissipate the heat conducted from the cooling unit to the outside and,
The cooling unit includes a plurality of heat pipes extending through the central portion along the direction of the basket axis and absorbing the residual heat of the basket and conducting to the heat dissipation unit,
The heat pipe communicates with the inner space of the reed so that a working fluid flows into the inner space of the reed to conduct heat and the working fluid in a vapor state is separated from the working fluid in a liquid state. . The method according to claim 1,
Further comprising spacers spaced along the axial direction within the cask to maintain the position and spacing of the baskets. The method according to claim 1,
And a shock-absorbing material located at the lower end of the cask. delete The method according to claim 1,
Wherein the heat pipe is installed at a measuring pipe or a guide pipe of spent nuclear fuel assemblies accommodated in the basket. delete The method according to claim 1,
And a neutron absorber provided inside the heat pipe to absorb neutrons. 8. The method of claim 7,
Wherein the heat pipe is spaced apart from the inner circumferential surface and has a baffle having a hole formed in the surface thereof. 9. The method of claim 8,
Wherein the lead has a plurality of bolts installed along the outer periphery and fastened to the top of the cask to seal the top of the cask.

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