DISPOSAL CONTAINER FOR HIGH-LEVEL RADIOACTIVE WASTE USING MULTIPLE BARRIERS AND BARRIER SYSTEM USING THEREOF

Abstract

The present invention relates to a disposal container and a storage system for high-level radioactive waste and, more specifically, to a disposal container for high-level radioactive waste using multiple barriers and a barrier system using thereof, the disposal container having the multiple barriers consisting of an inner wall made of carbon steel for excellent corrosion resistance and ease of manufacture, a middle wall made of Inconel, which is bonded to a lateral surface of the inner wall, and an outer wall made of copper, which is bonded to a lateral surface of the middle wall.

Claims

1. A disposal container of high-level radioactive waste using multiple barriers, comprising: an inner wall, made of carbon steel, for being cylindrical in shape; a middle wall, made of Inconel, for being cylindrical in shape and bonded to an outer surface of the inner wall; and an outer wall, made of copper, for being bonded to a lateral surface of the middle wall.

2. The disposal container of high-level radioactive waste using multiple barriers, according to claim 1, wherein the outer wall further installs a heat sink made of aluminum or copper and separated from a lateral surface for releasing heat which is generated inside and transferred to the outer wall, and a radiation fin made of materials same as the heat sink is combined between the heat sink and the outer wall.

3. The disposal container of high-level radioactive waste using multiple barriers, according to claim 2, wherein the radiation fin is combined to the lateral surface of the heat sink.

4. The disposal container of high-level radioactive waste using multiple barriers, according to claim 1, wherein a siphon pipe for storing refrigerants at a certain level is further installed between the heat sink and the outer wall, thereby making the inside in a vacuum state for releasing heat generated from the inside to the outer wall.

5. A barrier system using the disposal container of high-level radioactive waste using multiple barriers in claim 1, comprising: a disposal tunnel which is formed by digging rock formation; a deposition hole which is vertically or horizontally perforated, thereby storing the disposal container; and a buffer which is filled with the deposition hole and the disposal container.

6. The barrier system using the disposal container of high-level radioactive waste using multiple barriers according to claim 5, wherein the buffer is composed of Na-Bentonite.

Description

DESCRIPTION OF DRAWINGS

[0030] FIG. 1 illustrates a front sectional view showing the constitution of a disposal container of high-level radioactive waste using multiple barriers according to the present invention.

[0031] FIG. 2 illustrates a front sectional view showing the constitution of a disposal container of high-level radioactive waste using multiple barriers according to other embodiments of the present invention.

[0032] FIG. 3 illustrates a partial sectional perspective view of FIG. 2.

[0033] FIG. 4 illustrates a front sectional view showing the constitution of a disposal container of high-level radioactive waste using multiple barriers according to another embodiments of the present invention.

[0034] FIG. 5 illustrates a partial sectional perspective view of FIG. 4.

[0035] FIGS. 6 to 8 illustrate sectional views showing the constitution of a barrier system using the disposal container of high-level radioactive waste using multiple barriers according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The configuration of a disposal container of high-level radioactive waste using multiple barriers of the present invention will be described in detail with the accompanying drawings.

[0037] In the following description of the present invention, a detailed description of known incorporated functions and configurations will be omitted when to include them would make the subject matter of the present invention rather unclear. Also, the terms used in the following description are defined taking into consideration the functions provided in the present invention. The definitions of these terms should be determined based on the whole content of this specification, because they may be changed in accordance with the option of a user or operator or a usual practice.

[0038] FIG. 1 illustrates a front sectional view showing the constitution of a disposal container of high-level radioactive waste using multiple barriers according to the present invention; FIG. 2 illustrates a front sectional view showing the constitution of a disposal container of high-level radioactive waste using multiple barriers according to other embodiments of the present invention; FIG. 3 illustrates a partial sectional perspective view of FIG. 2; FIG. 4 illustrates a front sectional view showing the constitution of a disposal container of high-level radioactive waste using multiple barriers according to another embodiments of the present invention; and FIG. 5 illustrates a partial sectional perspective view of FIG. 4.

[0039] Referring to FIGS. 1 to 5, a disposal container of high-level radioactive waste using multiple barriers (10) according to the present invention consists of an inner wall (11), a middle wall (12) and an outer wall (13).

[0040] First, the inner wall (11) made of carbon steel for excellent economic value and ease of manufacture is cylindrical in shape. Hereinafter, it is desirable that an upper side of the inner wall (11) is open for storing high-level radioactive waste inside, and a thickness may be adjustable optionally.

[0041] Further, the middle wall (12) made of Inconel for excellent corrosion resistance is bonded to a lateral surface of the inner wall. Hereinafter, it is desirable that an upper side of the middle wall (12) is open for storing high-level radioactive waste inside equally to the inner wall (11), and a thickness may be adjustable optionally.

[0042] Further, the outer wall (13) made of copper for excellent corrosion resistance is bonded to a lateral surface of the middle wall (12). Hereinafter, it is desirable that an upper side of the outer wall (13) is open for storing high-level radioactive waste inside equally to the inner wall (11), and a thickness may be adjustable optionally.

[0043] Meanwhile, the upper sides of the inner wall (11), the middle wall (12), and the outer wall (13) are bonded to a cover (14), wherein a thickness of the cover (14) is the same with that of the upper sides of the inner wall (11), the middle wall (12), and the outer wall (13), by triplex-forming from a bottom in a series of carbon steel, Inconel, and copper.

[0044] Continuously, as illustrated in FIGS. 2 and 3, the disposal container of high-level radioactive waste using multiple barriers (10) according to the present invention further installs a heat sink (15) made of aluminum or copper and separated from a lateral surface for releasing heat which is generated inside the inner wall (11) and transferred to the outer wall (13).

[0045] Further, a radiation fin (16) made of materials same as the heat sink (15) is vertically combined between the heat sink (15) and the outer wall (13), and the radiation fin (16) is vertically combined even to the lateral surface of the heat sink (15), selectively.

[0046] The strength between the heat sink (15) and the outer wall (13) may be further reinforced by installing such radiation fin (16).

[0047] Further, if a thickness of the radiation fin (16) is thin in the center and gets thicker towards the outside, thin parts are broken under earthquake and shock is absorbed, thereby further enabling to improve seismic performance.

[0048] Further, as illustrated in FIGS. 4 and 5, a siphon pipe (17) for storing refrigerants at a certain level may be further installed between the heat sink (15) and the outer wall (13), thereby making the inside in a vacuum state for releasing heat generated from the inside of the inner wall (11) and transferred to the outer wall (13).

[0049] Hereinafter, in the siphon pipe (17), if heat generated from high-level radioactive waste is transferred through the inner wall (11), the middle wall (12), and the outer wall (13), the refrigerants vaporize into steam due to transferred heat and move up; the vaporized steam frozen by temperature of the heat sink (15) is converted to liquid refrigerants and moves down; vaporization and falling are repeated, thereby cooling the outer wall (13) and transferring cooling heat to the outer wall (13), the middle wall (12), and the inner wall (11).

[0050] Hereinafter, the constitution of a barrier system using a disposal container of high-level radioactive waste using multiple barriers according to the present invention will be described in detail with the accompanying drawing.

[0051] FIGS. 6 to 8 illustrate sectional views showing the constitution of a barrier system using the disposal container of high-level radioactive waste using multiple barriers according to the present invention.

[0052] Referring to FIGS. 6 to 8, the barrier system using a disposal container of high-level radioactive waste using multiple barriers (1) according to the present invention consists of a disposal tunnel (A), a deposition hole (B), a disposal container (10), and a buffer (20).

[0053] First, the disposal tunnel (A), as a general structure, is formed by digging rock formation.

[0054] Further, the deposition hole (B) is vertically or horizontally perforated in the disposal tunnel (A), thereby storing the disposal tunnel (A).

[0055] Further, as explained above, the disposal container (10) is composed of the inner wall (11), the middle wall (12) and the outer wall (13). Here, in the disposal container (10), the heat sink (15) is installed to the outer wall (13); and the radiation fin (16) may be further installed between the outer wall (13) and the heat sink (15), and the heat sink (15) outside, or the siphon pipe (17) may be installed between the heat sink (15) and the outer wall.

[0056] Further, the buffer (20) is filled in the space between the deposition hole (B) and the disposal container (10). Here, it is desirable that Na-bentonite is used in the buffer (20), and the buffer (20) may be block-shaped.

[0057] Meanwhile, if high-level waste repositories are constructed in deep crystalline rock, the buffer is compulsorily installed to prevent inflow of underground water through rock fracture, the disposal container corroded, and radioactive nuclide discharged. Along with the disposal container, the buffer is a key component of technological wall in high-level waste repositories. After digging deposition holes on the bottom of disposal cave and positioning the disposal container with wrapped waste, the buffer is installed by filling in the space between the disposal container and the rock wall of the deposition holes. The main functions of the buffer in the waste repositories are inflow suppression of underground water, control of discharge of radioactive nuclide, prevention of disposal container against external stress, and dispersion of decay heat, generated from waste, towards the outside, as well.

[0058] For selecting a suitable material as a buffer in high-level waste repositories, several countries have conducted on many substances. As a survey result, it is revealed that clay-based material and cement-based material may be utilized as a buffer. However, the cement material increases pH of underground water more than 12.5, and it may be possible to accelerate erosion of disposal container in such pH condition. Thus, clay-based material is more preferred, as a buffer.

[0059] The clay-based material has different physicochemical characteristics in accordance with constitutional minerals. As major minerals, there are Kaolinite, Illite, Montmorillonite, etc. Among them, Montmorillonite has higher swelling degrees than Kaolinite or Illite, thereby having much lower hydraulic conductivity under identical dry density. Also, since cation exchange capacity (CEC) and nuclide distribution coefficients are high due to large specific surface areas, it turns out to be superior as compared to other minerals even in radionuclide-retarding capacity. Thus, the more the clay-based material has Montmorillonite, the more it is known as being suitable as a buffer. Bentonite is a clay-based material, wherein it is primarily composed of Montmorillonite, thereby more preferring as buffer candidate than other clay in many countries currently planning on repository construction.

[0060] In contact with water, Bentonite has swelling degrees, wherein interlayer of Montmorillonite is hydrated and volume is increased. After placing the disposal container in the deposition hole, the empty space between the disposal container and the deposition holes is filled with Bentonite buffers, thereby swelling in contact with water when underground water from surrounding rocks gets through the inside of the deposition holes and then, blocking underground water penetration. Since Bentonite has extremely high swelling degrees as compared to other clay, empty spaces may be filled up by means of swelling when there are empty spaces or cracks in the buffer while installing the buffer. Also, Bentonite has high absorption capacity towards most of cationic nuclides, thereby effectively enabling to prevent radioactive nuclides to be discharged to surrounding rocks in case that radioactive nuclides are discharged from waste. Besides, Bentonite is a stabilized natural material form by long-term conformational changes, thereby enabling to maintain long-term stabilization by keeping original states without characteristics changes during life time of high-level waste disposal plant.

[0061] Bentonite may be classified into Na-Bentonite and Ca-Bentonite in accordance with types of exchangeable cation which exists in layers of Montmorillonite. Generally, Na-Bentonite has higher swelling than that of Ca-Bentonite and thus, it is known as more suitable buffer.

[0062] It is desirable that Na-Bentonite is used in the present invention.

[0063] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

EXPLANATIONS OF NUMERAL REFERENCE

[0064]

TABLE-US-00001 1: barrier system 10: disposal container 11: inner wall 12: middle wall 13: outer wall 14: cover 15: heat sink 16: radiation fin 17: siphon pipe 20: buffer A: disposal tunnel B: deposition hole