Nuclear reactor structure for forming nuclear fuel solidification layer

Abstract

One embodiment of the present invention provides a nuclear reactor structure comprising: a nuclear fuel storage part in which molten nuclear fuel is stored; a heat pipe filled with a working fluid having a temperature lower than the temperature of the molten nuclear fuel; a heat pipe jacket which forms a space in which the heat pipe can be disposed, and in which a heat transfer fluid is filled in the space; and a housing in which the nuclear fuel storage part and the heat pipe jacket are formed, wherein a nuclear fuel solidification layer is formed between the molten nuclear fuel and the heat pipe.

Description

Reactor structure forming a nuclear fuel solidification layer

[0001] The present invention relates to a nuclear reactor structure, and more particularly, to a nuclear reactor structure forming a nuclear fuel solidification layer.

[0002] Nuclear reactors that utilize domestic and foreign liquid nuclear fuel (molten salt reactors, liquid metal reactors, etc.) are attracting attention as next-generation nuclear reactors.

[0003] Research is actively underway on nuclear design, thermal-hydraulic design, and other methods for generating and utilizing nuclear fission energy in nuclear reactors. However, due to the highly reactive nature of liquid nuclear fuel, material issues such as corrosion and deterioration in structures in contact with the fuel remain unresolved. Furthermore, liquid-fuel reactors primarily operate at high temperatures, further increasing the fuel's reactivity.

[0004] Existing research to address this issue is broadly divided into structural materials and coating materials for internal coating. Research on structural materials primarily focuses on nickel-based alloys, while oxides such as magnesium oxide and silica carbide are being studied for internal coatings. However, nickel-based structural materials are unable to prevent corrosion in moist environments, so even small amounts of moisture in liquid nuclear fuel can still cause structural corrosion. Furthermore, oxide-based internal coatings are prone to cracking during temperature changes due to their inherent brittle nature.

[0005] Therefore, research is required to solve the corrosion problem of nuclear reactor structures.

[0006] The technical problem to be achieved by the present invention is to provide a reactor structure that prevents corrosion of the housing of the reactor structure and thereby improves the soundness of the structure.

[0007] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0008] In order to achieve the above technical task, one embodiment of the present invention provides a reactor structure including a nuclear fuel storage unit in which molten nuclear fuel is stored, a heat pipe filled with a working fluid having a temperature lower than a temperature of the molten nuclear fuel, a heat pipe jacket forming a space in which the heat pipe can be placed and the space being filled with a heat transfer fluid, and a housing in which the nuclear fuel storage unit and the heat pipe jacket are formed, wherein a nuclear fuel solidification layer is formed between the molten nuclear fuel and the heat pipe.

[0009] In an embodiment of the present invention, the heat pipe may include a heat pipe inner wall layer forming a working fluid receiving space in which the working fluid is received, an adhesive layer formed in a form that surrounds the heat pipe inner wall layer, a heat pipe capsule formed in a form that surrounds the adhesive layer, and a covering layer provided on an outer surface of the heat pipe capsule.

[0010] In an embodiment of the present invention, the thickness of the nuclear fuel solidification layer may be determined according to at least one parameter of the thermal resistance between the molten nuclear fuel and the surface of the nuclear fuel solidification layer, the thermal resistance within the nuclear fuel solidification layer, the thermal resistance within the structural material of the cladding layer and the heat pipe capsule, and the thermal resistance in the heat transfer fluid.

[0011] In an embodiment of the present invention, the parameters for determining the thickness of the nuclear fuel solidification layer may further include at least one of the outer diameter and thickness of the inner wall layer of the heat pipe, the inner diameter and thickness of the heat pipe capsule, the outer diameter and thickness of the heat pipe capsule, the outer diameter and thickness of the cladding layer, the outer wall temperature of the inner wall layer of the heat pipe, the type of the molten nuclear fuel, and the number of heat pipes provided inside the reactor structure.

[0012] In an embodiment of the present invention, the thickness of the nuclear fuel solidification layer can be calculated using the thermal resistance of the nuclear fuel solidification layer, the inner radius of the nuclear fuel solidification layer, the length of the nuclear fuel solidification layer, and the thermal conductivity of the nuclear fuel solidification layer.

[0013] In an embodiment of the present invention, the heat transfer fluid comprises at least one of an alkali metal including sodium or potassium, a metal including lead-bismuth and gallium, a non-metal including a molten salt and a high-temperature resistant oil, wherein the high-temperature resistant oil may be at least one of a silicone oil, a synthetic oil, a polyphenyl ether (PPE), a polyester, a perfluoropolyether (PFPE), a paraffin oil, a polyalphaolefin (PAO), a multialkylated naphthalene (MAN), and a diphenyl ether mixture.

[0014] In an embodiment of the present invention, the heat pipe and the heat pipe jacket may have a cylindrical shape.

[0015] According to an embodiment of the present invention, direct contact between high-temperature molten nuclear fuel (LF) and the housing can be prevented by the nuclear fuel solidification layer (SF), thereby significantly reducing the corrosion or deterioration rate of the housing.

[0016] The effects of the present invention are not limited to the above-described effects, and should be understood to include all effects that can be inferred from the composition of the invention described in the description or claims of the present invention.

[0017] Figure 1 is a drawing schematically illustrating the configuration of a reactor structure according to one embodiment of the present invention.

[0018] FIG. 2 is a drawing showing a heat pipe arranged inside a reactor structure according to one embodiment of the present invention.

[0019] Figure 3 is an enlarged view showing the configuration of a heat pipe according to one embodiment of the present invention.

[0020] FIG. 4 is a table showing parameters for determining the thickness of a nuclear fuel solidification layer and the size of each parameter according to one embodiment of the present invention.

[0021] Figure 5 is a conceptual diagram showing that direct contact between molten nuclear fuel and a housing can be prevented by creating a nuclear fuel solidification layer according to the present invention.

[0022] Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention can be implemented in various different forms and is therefore not limited to the embodiments described herein. In the drawings, irrelevant parts have been omitted for clarity of description, and similar parts have been designated with similar reference numerals throughout the specification.

[0023] Throughout the specification, when a part is said to be "connected (connected, contacted, or coupled)" to another part, this includes not only cases where it is "directly connected," but also cases where it is "indirectly connected" with another part in between. Furthermore, when a part is said to "include" a component, this does not exclude other components, but rather implies that it may include other components, unless otherwise specifically stated.

[0024] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0026] Methods for continuously cooling the reactor structure described in the present invention include natural convection and forced convection cooling using a coolant, cooling using heat pipes, and cooling using refrigeration / radiative heat transfer. Below, the cooling method using heat pipes will be primarily described.

[0027] Figure 1 is a drawing schematically illustrating the configuration of a reactor structure according to one embodiment of the present invention.

[0028] Referring to FIG. 1, the reactor structure (10) of the present invention may include a housing (100), a nuclear fuel storage unit (200), a heat pipe jacket (300), and a heat pipe (400).

[0029] The housing (100) forms a frame of the reactor structure (10), and can be provided with a nuclear fuel storage unit (200) capable of accommodating molten nuclear fuel, and a heat pipe jacket (300) in which a heat pipe (400) can be placed.

[0030] A housing (100) according to one embodiment of the present invention may be formed of an alloy having high heat resistance, corrosion resistance, and radiation resistance, and may be formed of a material including, for example, a nickel-based alloy or stainless steel, or may be formed of another high-temperature resistant metal material.

[0031] The nuclear fuel storage unit (200) provides a space capable of accommodating molten nuclear fuel (LF, Liquid Fuel) and can store molten nuclear fuel (LF) inside.

[0032] In one embodiment, the molten nuclear fuel (LF) may include molten salt nuclear fuel and molten metal nuclear fuel. The molten salt nuclear fuel may be formed by dissolving at least one of uranium, thorium, and plutonium in a salt (e.g., a fluorine salt, a chlorine salt, etc.), and the molten metal nuclear fuel may be formed by dissolving at least one of uranium, thorium, and plutonium in a metal (e.g., iron, manganese, chromium, etc.).

[0033] The heat pipe jacket (300) forms a space in which a heat pipe (400) can be placed, and the space can be filled with a heat transfer fluid (HTF).

[0034] For example, the heat transfer fluid (HTF) may include at least one of an alkali metal, a metal having a low freezing point, and a non-metal. Here, the alkali metal may be sodium or potassium, the metal having a low freezing point may be a lead-bismuth (Pb-Bi) alloy or gallium, and the non-metal may be a high-temperature resistant oil or molten salt.

[0035] The high temperature resistant oil may be, for example, at least one of Silicone Oil, Synthetic Oil, Polyphenyl Ether (PPE), Polyesters, Perfluoropolyether (PFPE), Paraffinic Oil, Polyalphaolefin (PAO), Multialkylated Naphthalene (MAN), and Diphenyl Ether Mixtures.

[0036] A heat pipe (400) can be inserted and placed inside a heat pipe jacket (300) filled with a heat transfer fluid (HTF).

[0037] The interior of the heat pipe (400) can be filled with a working fluid having a temperature lower than the temperature of the molten nuclear fuel (LF).

[0038] For example, the working fluid may include at least one of mercury, sodium (Na), potassium (K), lithium (Li), lead (Pb), and bismuth (Bi) alloys.

[0039] A heat pipe (400) according to one embodiment of the present invention is located on one side of a nuclear fuel storage unit (200), and a heat transfer phenomenon occurs by molten nuclear fuel (LF) located in an adjacent location.

[0040] As another example, the heat pipe jacket (300) may be formed inside the nuclear fuel storage unit (200) (see FIG. 4). Accordingly, the heat pipe (400) may be placed inside the nuclear fuel storage unit (200) containing the molten nuclear fuel (LF), so that heat exchange can occur with the molten nuclear fuel (LF) located around the entire surface of the heat pipe.

[0041] The heat pipe (400) can be formed in a cylindrical shape.

[0042] In addition, a plurality of heat pipes (400) can be provided inside the reactor structure (10), and it is preferable that the plurality of heat pipes (400) are arranged spaced apart from each other.

[0043] By heat exchange between the molten nuclear fuel (LF) stored in the nuclear fuel storage unit (200) and the heat pipe (400), a solidified fuel layer (SF) can be formed between the molten nuclear fuel (LF) and the heat pipe (400).

[0044] As the heat pipe (400) containing the working fluid acts as a cooling agent, the temperature of the outer wall of the heat pipe (400) becomes lower than the solidification point of the molten nuclear fuel (LF), so that the molten nuclear fuel is cooled around the heat pipe (400), and a nuclear fuel solidification layer (SF) can be formed between the molten nuclear fuel (LF) and the heat pipe (400).

[0045] The nuclear fuel solidification layer (SF) thus produced can be maintained in a solid state and can serve to prevent direct contact between the high-temperature molten nuclear fuel (LF) and the reactor structure (10). In other words, the nuclear fuel solidification layer (SF) plays an important role in reducing problems such as corrosion or deterioration of the reactor structure (10) and effectively maintaining structural integrity.

[0046] FIG. 2 is a drawing showing a heat pipe arranged inside a reactor structure according to one embodiment of the present invention, and FIG. 3 is an enlarged view showing the configuration of a heat pipe according to one embodiment of the present invention.

[0047] Referring to FIG. 2, the heat pipe (400) of the present invention may include a heat pipe inner wall layer (410), an adhesive layer (430), a heat pipe capsule (450), and a covering layer (470).

[0048] The heat pipe inner wall layer (410) can form a working fluid receiving space in which the working fluid is received. For example, the heat pipe inner wall layer (410) can be made of at least one of stainless steel, Inconel, cobalt alloys, and titanium.

[0049] The adhesive layer (430) may be formed in a form that surrounds the heat pipe inner wall layer (410). For example, the adhesive layer (430) may be made of at least one of lead, aluminum, copper, and solder alloys.

[0050] The heat pipe capsule (450) can be formed in a shape that surrounds the adhesive layer (430). The heat pipe capsule (450) can be made of at least one of stainless steel, a nickel-based alloy, and titanium.

[0051] A covering layer (470) may be provided on the outer surface of the heat pipe capsule (450). The covering layer (470) may be made of at least one of a ceramic coating material, a chromium coating material, and a carbide coating material.

[0052] According to one embodiment of the present invention, a heat pipe (400) is provided on the side of a nuclear fuel storage unit (200) located at the center of a nuclear reactor structure (10), as illustrated in FIG. 1, so that a nuclear fuel solidification layer (SF) can be formed on the inner wall of the nuclear fuel storage unit (200).

[0053] According to another embodiment of the present invention, a plurality of heat pipes (400) are arranged inside a nuclear fuel storage unit (200) in which molten nuclear fuel (LF) is stored, as shown in FIGS. 2 and 3, so that a nuclear fuel solidification layer (SF) can be formed along the circumference around the heat pipe (400) and the heat pipe jacket (300).

[0054] In order to prevent corrosion of the reactor structure (10), the thickness of the nuclear fuel solidification layer (SF) is important.

[0055] The thickness of the nuclear fuel solidification layer (SF) may be determined based on at least one parameter of the thermal resistance between the molten nuclear fuel (LF) and the surface of the nuclear fuel solidification layer (SF), the thermal resistance within the nuclear fuel solidification layer (SF), the thermal resistance within the structural material of the cladding layer (470) and the heat pipe capsule (450), and the thermal resistance in the heat transfer fluid (HTF).

[0056] The thermal resistance elements in the thermal resistance model from the molten nuclear fuel (LF) to the heat pipe (400) according to the present invention are the thermal resistance (natural convection heat transfer mechanism) between the surface of the molten nuclear fuel (LF) and the nuclear fuel solidification layer (SF), the thermal resistance (heat conduction mechanism) within the nuclear fuel solidification layer (SF), the thermal resistance (heat conduction mechanism) within the structural material of the cladding layer (470) and the heat pipe capsule (450), and the thermal resistance in the heat transfer fluid (HTF).

[0057] In addition, the parameters for determining the thickness of the nuclear fuel solidification layer (SF) may further include at least one of the outer diameter and thickness of the heat pipe inner wall layer (410), the inner diameter and thickness of the heat pipe capsule (450), the outer diameter and thickness of the heat pipe capsule (450), the outer diameter and thickness of the cladding layer (470), the outer wall temperature of the heat pipe inner wall layer (410), the type of molten nuclear fuel (LF), and the number of heat pipes (400) provided inside the reactor structure (10).

[0058] A more detailed description of the method for calculating the thickness of the nuclear fuel solidification layer (SF) using the above parameters is provided below.

[0059] The thickness of the nuclear fuel solidification layer (SF) can be calculated using the following <Mathematical Formula 1> and <Mathematical Formula 2>.

[0060]

[0061] Here, R 23 is the thermal resistance within the solidified fuel layer (SF), T2 is the surface temperature of the solidified fuel layer (SF), and T3 may be the internal temperature of the solidified fuel layer (SF). Here, T2 may be equal to the solidification point of the molten fuel (LF).

[0062]

[0063] Here, Outer radius is the outer radius of the nuclear fuel solidification layer (SF), Inner radius is the inner radius of the nuclear fuel solidification layer (SF), Length is the length of the nuclear fuel solidification layer (SF), and Thermal conductivity may be the thermal conductivity of the nuclear fuel solidification layer (SF).

[0064] And, the internal temperature (T3) of the nuclear fuel solidification layer can be calculated through <Mathematical Formula 3> below.

[0065]

[0066] Here, T6 is the temperature of the heat transfer fluid (HTF), and R 56is the thermal resistance of the adhesive layer (430), and R 45 is the thermal resistance of the heat pipe capsule (450), and R 34 may be the thermal resistance of the covering layer (470). Here, the temperature (T6) of the heat transfer fluid may be the same as the temperature of the inner wall layer (410) of the heat pipe.

[0067] FIG. 4 is a table showing parameters for determining the thickness of a nuclear fuel solidification layer and the size of each parameter according to one embodiment of the present invention.

[0068] Referring to FIG. 4, parameters for determining the thickness of the nuclear fuel solidification layer (SF) may include the outer diameter of the inner wall layer (410) of the heat pipe, the inner diameter and thickness of the heat pipe capsule (450), the outer diameter and thickness of the heat pipe capsule (450), the outer diameter and thickness of the cladding layer (470), the temperature of the inner wall layer (410) of the heat pipe, the type of nuclear fuel (eutectic point), and the number of heat pipes (400) (heat transfer amount).

[0069] The outer diameter of the heat pipe inner wall layer (410) may be 35 to 40 mm, preferably 38.1 mm. The inner diameter and thickness of the heat pipe capsule (450) may be 38 to 42 mm (0.8 to 1.2 mm), preferably 40.1 mm (1 mm). The outer diameter of the heat pipe capsule (450) may be 40 to 42 mm, preferably 42.1 mm. The outer diameter of the covering layer (470) (D1 in FIG. 2) may be 42 to 46 mm, preferably 44.1 mm. The outer wall temperature of the heat pipe inner wall layer (410) may be 665 to 685°C, preferably 675°C. The molten nuclear fuel (LF) may be made of a uranium-iron alloy, and the temperature at this time ((T in FIG. 2) LF ) may be 723°C. The number of heat pipes (400) may be 87 to 95, and preferably 91. The heat transfer amount of each heat pipe (400) may be 26.5 to 28.5 kW, and preferably 27.5 kW.

[0070] Variables output according to the conditions of the parameters as described above may include the internal surface temperature of the heat pipe capsule (450), the external surface temperature of the heat pipe capsule (450), the external surface temperature of the cladding layer (470), and the external diameter and thickness of the nuclear fuel solidification layer (SF).

[0071] The internal surface temperature of the heat pipe capsule (450) according to an embodiment of the present invention may be 675 to 680°C, preferably 677.9°C. The external surface temperature of the heat pipe capsule (450) may be 685 to 690°C, preferably 688.2°C. The external surface temperature of the covering layer (470) (T in FIG. 2) 470 ) may be 690 to 695°C, and preferably 693.0°C. In addition, the outer diameter (D2 in FIG. 2) and thickness of the nuclear fuel solidification layer (SF) may be 54 to 56 mm (5 to 6 mm), and preferably 55.1 mm (5.5 mm).

[0072] Additionally, the spacing between the plurality of heat pipes (400) (D3 in FIG. 2) may be 75 to 77 mm, and preferably 76 mm.

[0073] In addition, in the method for calculating the thickness of the nuclear fuel solidification layer (SF) according to the present invention, the outer wall temperature of the inner wall layer (410) of the heat pipe can be set to be maintained at a constant temperature.

[0074] Figure 5 is a conceptual diagram showing that direct contact between molten nuclear fuel and a housing can be prevented by creating a nuclear fuel solidification layer according to the present invention.

[0075] Direct contact between the high-temperature molten nuclear fuel (LF) and the housing (100) can be prevented by the nuclear fuel solidification layer (SF) formed to a preset thickness through the method described above, so there is an advantage in that the corrosion or deterioration rate of the housing (100) can be significantly reduced.

[0076] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0077] The scope of the present invention is indicated by the claims set forth below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. A nuclear fuel storage unit where molten nuclear fuel is stored, A heat pipe filled with a working fluid having a temperature lower than the temperature of the molten nuclear fuel, A heat pipe jacket that forms a space in which the heat pipe can be placed, and the space is filled with a heat transfer fluid; Including a housing in which the nuclear fuel storage unit and the heat pipe jacket are formed, A reactor structure characterized in that a nuclear fuel solidification layer is formed between the molten nuclear fuel and the heat pipe.

2. In paragraph 1, The above heat pipe, A heat pipe inner wall layer forming a working fluid receiving space in which the working fluid is received, An adhesive layer formed in a form that wraps around the inner wall layer of the heat pipe, A heat pipe capsule formed in a form that wraps the above adhesive layer, A reactor structure characterized by including a covering layer provided on the outer surface of the heat pipe capsule.

3. In paragraph 2, The above nuclear fuel solidification layer is, A reactor structure characterized in that the thickness is determined according to at least one parameter of the thermal resistance between the molten nuclear fuel and the surface of the nuclear fuel solidification layer, the thermal resistance within the nuclear fuel solidification layer, the thermal resistance within the structural material of the cladding layer and the heat pipe capsule, and the thermal resistance in the heat transfer fluid.

4. In paragraph 3, The parameter that determines the thickness of the above nuclear fuel solidification layer is: A reactor structure characterized in that it further includes at least one of the outer diameter and thickness of the inner wall layer of the heat pipe, the inner diameter and thickness of the heat pipe capsule, the outer diameter and thickness of the heat pipe capsule, the outer diameter and thickness of the covering layer, the outer wall temperature of the inner wall layer of the heat pipe, the type of the molten nuclear fuel, and the number of heat pipes provided inside the reactor structure.

5. In paragraph 3, The thickness of the above nuclear fuel solidification layer is A reactor structure characterized in that it is calculated using the thermal resistance of the nuclear fuel solidification layer, the inner radius of the nuclear fuel solidification layer, the length of the nuclear fuel solidification layer, and the thermal conductivity of the nuclear fuel solidification layer.

6. In paragraph 1, The above heat transfer fluid is, Containing at least one of alkali metals including sodium or potassium, metals including lead-bismuth and gallium, and non-metals including molten salts and high-temperature resistant oils; The above high temperature resistant oil is, A reactor structure characterized by at least one of silicone oil, synthetic oil, polyphenyl ether (PPE), polyesters, perfluoropolyether (PFPE), paraffinic oil, polyalphaolefin (PAO), multialkylated naphthalene (MAN), and diphenyl ether mixtures.

7. In paragraph 1, The above heat pipe and the above heat pipe jacket, A reactor structure characterized by a cylindrical shape.

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