System for replacing core of small modular reactor and method for replacing core thereby

Abstract

The present invention relates to a system for replacing the core of a small modular reactor (SMR), the system comprising a reactor vessel accommodating a core, a containment vessel surrounding the reactor vessel, and a structure external to the containment vessel. A sealing structure, which is an essential component of the present invention, is normally disposed at a first location in the structure and, when the heads of the reactor vessel and the containment vessel are removed during core replacement, the sealing structure moves to a second location which is the space from which the heads have been removed. After moving, the sealing structure separates and seals the lower containment space in which the reactor vessel body is located and the upper structure space which is open to the outside. Therefore, the present invention is advantageous in that the leakage of radioactive materials during the core replacement work is effectively prevented, and the safety of the working space is assured, thereby significantly improving the efficiency and safety of core replacement.

Description

Core replacement system for a small modular reactor and core replacement method using the same

[0001] The present invention relates to a core replacement system for a small modular reactor and a core replacement method using the same.

[0002] In existing large nuclear power plants or underwater small reactors, since the reactor is located within a refueling pool, there was the inconvenience of having to perform nuclear fuel replacement underwater in a pool filled with refueling water.

[0003] In addition, in the case of existing sealing systems, the space between the wall and the CV is blocked, so a problem occurred in which residual heat could not escape smoothly during normal operation and after reactor shutdown.

[0004] The objective of the present invention is to provide a core replacement system for a small modular reactor and a core replacement method using the same.

[0005] The present invention relates to a core replacement system for a small modular reactor (SMR), comprising: a reactor vessel (RV) that accommodates the core and a steam generator and includes an RV head at the top and an RV body at the bottom; a containment vessel (CV) that accommodates the reactor vessel and surrounds the reactor vessel, includes a CV head at the top and a CV body at the bottom, and forms a first CV space surrounding the RV head and a second CV space surrounding the RV body; a structure that accommodates the containment vessel, surrounds the containment vessel, and forms a first structural space surrounding the CV head and a second structural space surrounding the CV body; and a sealing structure that is positioned at a first location accommodated within the structure, moves to a second location in the first structural space when the RV head and CV head are removed for the core replacement operation, and separates the second CV space from the first structural space.

[0006] The sealing structure may include: a hinge portion rotatably coupled inside the wall of the first structure space; and a sealing plate connected to the hinge portion and separating the second CV space and the first structure space by rotation.

[0007] The sealing plate may comprise a pair of left and right plates, a through hole formed in the center that communicates the RV space and the first structure space, and a stepped joint portion that joins the pair of sealing plates so as to overlap each other.

[0008] The sealing plate is disposed at the stepped joint and further includes a lug that moves the pair of sealing plates from the first position to the second position, and the lug may be connected to a crane capable of lifting the sealing plate.

[0009] The present invention relates to a core replacement method for a small modular reactor (SMR) using a core replacement system according to claim 1, comprising: (a) removing the head of the reactor vessel (RV) and the head of the containment vessel (CV) of the SMR; (b) moving the sealing structure from the first position to the second position; (c) separating the second CV space inside the containment vessel from the first structural space of the structure using the sealing structure; (d) filling the first structural space and the reactor vessel interior space with cooling water; and (e) replacing the core while the cooling water is filled.

[0010] In step (b) above, by moving the sealing structure from the first position to the second position, the first structure space and the second structure space are separated, the first CV space and the second CV space are separated, and the containment vessel interior space and the first structure space can be connected.

[0011] The above step (b) can be performed by lifting the sealing structure using a crane connected to the lug of the sealing structure.

[0012] The above step (c) may include the step of separating the second CV space from the first structure space by rotating the sealing structure using the hinge portion of the sealing structure.

[0013] In step (d) above, the first structure space and the containment vessel may be filled with cooling water, while the second structure space and the second CV space may not be filled with cooling water.

[0014] After step (e) above, the method may further include: a step of removing the cooling water filled in the space of the first structure; a step of returning the sealing structure from the second position to the first position; and a step of joining the head of the reactor vessel (RV) and the head of the containment vessel (CV).

[0015] According to the present invention, a core replacement system for a small modular reactor and a core replacement method using the same are provided.

[0016] FIG. 1 shows a core replacement system for a small modular reactor according to an embodiment of the present invention, and

[0017] FIGS. 2 to 5 show a sealing structure within a core replacement system of a small modular reactor according to an embodiment of the present invention, and

[0018] FIGS. 6a and 6b illustrate the operation of a sealing structure within a core replacement system of a small modular reactor according to an embodiment of the present invention, and

[0019] FIG. 7 is a flowchart illustrating a core replacement method using a core replacement system of a small modular reactor according to an embodiment of the present invention, and

[0020] FIGS. 8a to 8e illustrate, in steps, a core replacement method using a core replacement system of a small modular reactor according to an embodiment of the present invention.

[0021] The present invention will be described in more detail below with reference to the drawings.

[0022] The attached drawings are merely examples illustrated to further explain the technical concept of the present invention, and therefore the concept of the present invention is not limited to the attached drawings. Additionally, the sizes and spacing, etc., in the attached drawings may be exaggerated from reality to explain the relationships between the components.

[0023] With reference to FIGS. 1 to 5, a system for replacing the core of a small modular reactor (SMR) according to an embodiment of the present invention (hereinafter referred to as the “system”) will be described.

[0024] FIG. 1 shows a core replacement system for a small modular reactor according to an embodiment of the present invention, and FIGS. 2 to 5 show a sealing structure within a core replacement system for a small modular reactor according to an embodiment of the present invention.

[0025] The system (10) includes a reactor vessel (RV, 100), a containment vessel (CV, 200), a structure (300), and a sealing structure (400).

[0026] The reactor vessel (RV, 100) is a vessel that accommodates the core (110) and steam generator (120) of an SMR (though not shown).

[0027] The reactor vessel (100) includes an RV head (101) at the top and an RV body (102) at the bottom. The core (110) is located inside the reactor vessel (100) and generates thermal energy through a nuclear fission reaction. The steam generator (120) generates steam using the thermal energy generated in the core (110).

[0028] The RV head (101) is located at the top of the reactor vessel (100) and serves to seal the internal components of the reactor vessel (100) from the external environment.

[0029] The RV head (101) may have multiple through holes to allow various equipment, such as a control rod drive unit (CEDM) and a core instrument, to pass through when the core (110) is replaced. Additionally, the RV head (101) may be equipped with a cooling water inlet and outlet, a safety valve, and a connection part for instrumentation (although not shown).

[0030] The RV head (101) can be made of a durable and corrosion-resistant material, such as stainless steel or a special alloy, to withstand high temperature, high pressure, and radiation environments.

[0031] The RV body (102) is located at the bottom of the reactor vessel (100) and serves to support the core (110) and guide the flow of cooling water.

[0032] Inside the RV body (102), nuclear fuel assemblies, control rod assemblies, and core support structures constituting the core (110) are installed.

[0033] The RV body (102) is made of thick steel to withstand high temperature and pressure, and may have a channel for cooling water to flow through it formed inside. Additionally, (although not illustrated) the RV body (102) may have neutron shielding material and gamma ray shielding material attached to its inner wall to perform a shielding function against neutrons and gamma rays.

[0034] The RV head (101) and the RV body (102) may be connected using a flange and a stud bolt, but are not limited thereto. Additionally, a sealing material such as an O-ring may be inserted between the RV head (101) and the RV body (102) to prevent high-temperature, high-pressure cooling water from leaking.

[0035] The containment vessel (CV, 200) accommodates the reactor vessel (100) and surrounds the reactor vessel (100).

[0036] The containment vessel (CV, 200) is a secondary protective barrier surrounding the reactor vessel (RV, 100) and plays a very important role in preventing the leakage of radioactive material that may occur in the RV (100). The containment vessel (200) consists of an upper CV head (201) and a lower CV body (202).

[0037] The CV head (201) may be a dome-shaped structure that encloses the RV head (101) of the reactor vessel (RV, 100). (Although not illustrated) The CV head (201) may have multiple through holes to allow various equipment, such as a control rod drive unit (CEDM) and a core instrument, to pass through, just like the RV head (101). Additionally, the CV head (201) may be further equipped with a coolant inlet and outlet, a safety valve, and a connection for instrumentation.

[0038] The CV body (202) may be a cylindrical structure that surrounds the RV body (102) of the reactor vessel (RV, 100). The CV body (202) is installed at a certain distance from the RV body (102) to form a second CV space (220). This space serves to collect and isolate radioactive material leaking from the RV (100) in the event of an accident.

[0039] (Although not shown) inside the CV main body (202), a hydrogen recombinator for removing hydrogen gas generated in the event of an accident and measuring equipment for monitoring the pressure and temperature inside the containment vessel (200) may be further installed. The CV main body (202) may also be made of thick steel to withstand high temperature, high pressure, and radiation environments.

[0040] The CV head (201) can be made of a durable and corrosion-resistant material, such as stainless steel or a special alloy, to withstand high temperature, high pressure, and radiation environments.

[0041] The CV head (201) and the CV body (202) may be connected using a flange and a stud bolt, similar to the RV head (101) and the RV body (102), but are not limited thereto. Additionally, a sealing material such as an O-ring may be inserted between the CV head (201) and the CV body (202) to prevent high-temperature, high-pressure cooling water or steam from leaking.

[0042] The containment vessel (200) forms a first CV space (210) surrounding the RV head (101) and a second CV space (220) surrounding the RV body (102). Here, the first CV space (210) is the space between the RV head (101) and the CV head (201), where cooling water and steam piping, control rod drive devices (CEDM), etc. are located. The second CV space (220) is the space between the RV body (102) and the CV body (202), and serves to suppress the spread of radioactive material in the event of an accident.

[0043] The containment vessel (200) serves to prevent leakage of radioactive material that may occur in the reactor vessel (100).

[0044] The structure (300) accommodates the containment vessel (200) and surrounds the containment vessel (200). Here, the structure (300) is the outermost protective wall surrounding the containment vessel (CV, 200), and is positioned between the containment vessel (200) and the external environment to protect and support the containment vessel (200).

[0045] In addition, it also serves to guide and support the movement of the sealing structure (400). The structure (300) is composed of a first structure space (310) surrounding the CV head (201) and a second structure space (320) surrounding the CV body (202).

[0046] The structure (300) forms a first structure space (310) surrounding the CV head (201) and a second structure space (320) surrounding the CV body (202). The structure (300) serves to protect and support the containment vessel (200).

[0047] The first structural space (310) is located above the CV head (201) and is the space between the CV head (201) and the structural space (300). This space accommodates the sealing structure (400) when it moves from the first position (P1) to the second position (P2) and provides sufficient space for the hinge portion (410) of the sealing structure (400) to rotate. Additionally, the first structural space (310) provides a space where workers can work safely during core replacement operations.

[0048] The second structural space (320) is a space that surrounds the outside of the CV body (202) and is the space between the CV body (202) and the structure (300). This space primarily serves to protect the containment vessel (200) from external impacts and maintain the structural stability of the containment vessel (200). Additionally, facilities for cooling and temperature control of the containment vessel (200) may be further installed in the second structural space (320).

[0049] The structure (300) can generally be made of a rigid material such as reinforced concrete or steel. Additionally, the structure (300) may have neutron shielding and gamma ray shielding materials attached to its inner walls to perform a radiation shielding function.

[0050] The sealing structure (400) serves to separate the second CV space (220) from the first structure space (310). Here, the sealing structure (400) plays an important role in thoroughly preventing the leakage of radioactive material by separating the second CV space (220) from the first structure space (310) during the core replacement process of the SMR.

[0051] That is, the sealing structure (400) is normally safely stored in the first position (P1) inside the structure (300), but when the core replacement operation begins, it moves to the first structure space (310) with the RV head (101) and CV head (201) removed and is positioned at the second position (P2).

[0052] Referring to FIGS. 2 to 5, the sealing structure (400) includes a hinge portion (410), a sealing plate (420), and a lug (430).

[0053] Referring to FIGS. 2 and 3, the hinge portion (410) is installed inside the wall of the first structural space (310) and serves to rotatably support the sealing plate (420).

[0054] The hinge portion (410) forms the rotation axis of the sealing plate (420) and allows the sealing plate (420) to move smoothly between the first position (P1) and the second position (P2).

[0055] The hinge portion (410) can be made of a material that is highly durable and resistant to corrosion, for example, stainless steel or a special alloy. Additionally, the hinge portion (410) must have sufficient strength to withstand the weight of the sealing plate (420) and may include rotational support parts such as bearings to facilitate the smooth rotation of the sealing plate (420).

[0056] Referring to FIG. 4, the sealing plate (420) is composed of a left and right pair and is rotatably supported by a hinge part (410).

[0057] Referring to FIGS. 4 and 5, the sealing plate (420) serves to separate the first structural space (310) and the second structural space (320) at the first position (P1), and to separate the second CV space (220) and the first structural space (310) at the second position (P2). The sealing plate (420) connects the RV space (105) and the first structural space (310) through a through hole (421) formed in the center.

[0058] Referring to FIG. 3, the sealing plate (420) includes a stepped joint (422) that joins a pair of them so as to overlap each other, thereby improving sealing performance.

[0059] The sealing plate (420) can be made of a material with excellent heat resistance, pressure resistance, and radiation resistance, for example, carbon steel, stainless steel, or a special alloy. In addition, the sealing plate (420) may be coated with a corrosion-resistant coating on its surface to prevent corrosion caused by contact with cooling water.

[0060] Referring to FIG. 4, the lug (430) is placed on the stepped joint (422) of the sealing plate (420) and serves to move the sealing plate (420) from the first position (P1) to the second position (P2).

[0061] The lug (430) is connected to a crane to lift the sealing plate (420). The lug (430) must have sufficient strength to withstand the weight of the sealing plate (420) and may include a loop or hook for connection to the crane. Additionally, the lug (430) may include a shock absorber to absorb shocks generated during the movement and rotation of the sealing plate (420).

[0062] With reference to FIGS. 6a and 6b, the operation of a sealing structure within a core replacement system of a small modular reactor according to an embodiment of the present invention will be described.

[0063] Referring to FIG. 6a, the sealing structure (400) is normally safely stored in a first position (P1) inside the structure (300), but when the core replacement operation begins, it moves to the first structure space (310) with the RV head (101) and CV head (201) removed and is positioned at a second position (P2). At this time, the movement of the sealing structure (400) is performed using a lug (430) placed on the stepped joint (422) of the sealing plate (420).

[0064] The lug (430) is connected to a crane capable of lifting the sealing plate (420), and moves the sealing structure (400) up and down through the operation of the crane.

[0065] Subsequently, as shown in FIG. 6b, when the sealing structure (400) reaches the second position (P2), it rotates around the hinge portion (410) to separate the second CV space (220) and the first structure space (310). At the same time, the first structure space (310) and the second structure space (320) are separated, and the internal space of the containment vessel (200) and the first structure space (310) are connected. In this state, the first structure space (310) and the internal space of the reactor vessel (100) are filled with cooling water.

[0066] (Although not illustrated) a separate opening may be formed in the lower part of the structure (300) through which a sealing structure (400) can pass, and the sealing structure (400) can exit to the outside through the opening and move to a separate module. At this time, the sealing structure (400) can move via an extended rail connected to the structure (300).

[0067] A method for replacing the core of a small modular reactor according to an embodiment of the present invention will be described with reference to FIGS. 7 and FIGS. 8a to 8e.

[0068] FIG. 7 is a flowchart illustrating a core replacement method using a core replacement system of a small modular reactor according to an embodiment of the present invention, and FIGS. 8a to 8e illustrate a core replacement method using a core replacement system of a small modular reactor according to an embodiment of the present invention in steps.

[0069] A core replacement method according to one embodiment of the present invention is a method for safely and efficiently replacing the core of an SMR, and can effectively prevent leakage of radioactive material during the core replacement operation by separating the internal space of the containment vessel using a sealing structure. In addition, the core replacement operation can be easily performed through the movement and rotation of the sealing structure.

[0070] As shown in FIG. 8a, the sealing structure (400) is normally located at the first position (P1). At this time, the first CV space (210) and the second CV space (220) are connected to each other so that cooling water and steam can circulate freely.

[0071] When core replacement is required, the reactor vessel (RV) head (101) and the containment vessel (CV) head (201) of the SMR are removed as shown in FIG. 8b. (S100)

[0072] In step S100, the RV head (101) and the CV head (201) may be fastened to the RV body (102) and the CV body (202), respectively, by means of a flange and a stud bolt. In one embodiment of the present invention, the RV head (101) and the CV head (201) are removed by loosening the bolt and separating the flange, but the invention is not limited thereto.

[0073] Next, the sealing structure (400) is moved from the first position (P1) to the second position (P2). (S200)

[0074] In step S200, the lug (430) placed on the sealing plate (420) of the sealing structure (400) is moved by connecting it to a crane. As the sealing structure (400) is moved to the second position (P2) by the crane, the first structure space (310) and the second structure space (320) are separated, the first CV space (210) and the second CV space (220) are separated, and the internal space of the containment vessel and the first structure space (310) are connected.

[0075] Afterwards, as shown in FIGS. 8c and 8d, the second CV space (220) inside the containment vessel (200) is separated from the first structural space (310) of the structure (300) using a sealing structure (400). (S300)

[0076] In step S300, the sealing plate (420) is rotated using the hinge part (410) of the sealing structure (400) to separate the second CV space (220) from the first structure space (310).

[0077] Next, as shown in FIG. 8e, the step of filling the first structural space (310) and the internal space of the reactor vessel (100) with cooling water is performed. (S400)

[0078] The cooling water filled in the S400 stage serves to cool the core (110) and prevent the spread of radioactive material. At this time, cooling water is filled inside the first structural space (310) and the containment vessel (200), but cooling water is not filled in the second structural space (320) and the second CV space (220).

[0079] Afterwards, the core (110) is replaced while the coolant is filled. (S500)

[0080] In the S500 stage, the core (110) can be replaced by removing the spent nuclear fuel and loading new nuclear fuel.

[0081] (Although not illustrated) after step S500, the cooling water filled in the first structure space (310) is removed, and the sealing structure (400) is returned from the second position (P2) to the first position (P1), and then the reactor vessel (RV) head (101) and the containment vessel (CV) head (201) are joined.

[0082] The SMR core replacement system and method according to the present invention can effectively prevent leakage of radioactive material by using a sealing structure to communicate the internal space of the containment vessel with the outside only during core replacement work, and by separating the internal space of the containment vessel from the outside during normal operation mode.

[0083] Furthermore, economic efficiency can be improved by minimizing coolant usage during core replacement, and work efficiency can be enhanced through the movement and rotation of the sealing structure. In addition, the sealing structure features a simple design, making it easy to manufacture and maintain while ensuring high reliability.

[0084] Although the present invention has been described with reference to an embodiment illustrated in the accompanying drawings, this is merely illustrative, and those skilled in the art will understand that various modifications can be made to the present invention. Accordingly, the technical scope of protection of the present invention should be determined by the appended claims.

Claims

1. In a system for replacing the core of a Small Modular Reactor (SMR), A reactor vessel (RV) accommodating the above-mentioned core and steam generator, comprising an RV head at the top and an RV body at the bottom; A containment vessel (CV) that accommodates the reactor vessel and surrounds the reactor vessel, includes a CV head at the top and a CV body at the bottom, and forms a first CV space surrounding the RV head and a second CV space surrounding the RV body; A structure that accommodates the above-mentioned containment vessel, surrounds the above-mentioned containment vessel, and forms a first structural space surrounding the CV head and a second structural space surrounding the CV body; and A core replacement system comprising: a sealing structure that is positioned at a first location accommodated within the above structure, moves to a second location located in the first structure space when the RV head and CV head are removed for the core replacement operation, and separates the second CV space from the first structure space.

2. In Paragraph 1, The above sealing structure is, A hinge portion rotatably coupled inside the wall of the first structural space; and A core replacement system comprising: a sealing plate connected to the hinge portion and separating the second CV space and the first structure space by rotation.

3. In Paragraph 2, The above sealing plate is composed of a left and right pair, and A through hole formed in the center and communicating the RV space and the first structure space; and A core replacement system comprising a stepped joint that joins the above pair of sealing plates so as to overlap each other.

4. In Paragraph 3, The above sealing plate is, It further includes a lug disposed at the stepped joint and moving the pair of sealing plates from the first position to the second position, The above lug is a core replacement system connected to a crane capable of lifting the sealing plate.

5. A method for replacing the core of a Small Modular Reactor (SMR) using a core replacement system according to paragraph 1, (a) a step of removing the head of the reactor vessel (RV) and the head of the containment vessel (CV) of the above SMR; (b) a step of moving the sealing structure from the first position to the second position; (c) a step of separating the second CV space inside the containment vessel from the first structural space of the structure using the sealing structure; (d) a step of filling the space of the first structure and the space inside the reactor vessel with cooling water; and (e) a step of replacing the core while the coolant is filled; a core replacement method comprising.

6. In Paragraph 5, In the above step (b), A core replacement method in which the sealing structure moves from the first position to the second position, thereby separating the first structure space and the second structure space, separating the first CV space and the second CV space, and communicating the containment vessel interior space and the first structure space.

7. In Paragraph 6, The above step (b) is, A method for replacing a core by lifting the sealing structure using a crane connected to the lugs of the sealing structure.

8. In Paragraph 5, The above step (c) is, A core replacement method comprising the step of separating the second CV space from the first structure space by rotating the sealing structure using the hinge portion of the sealing structure.

9. In Paragraph 5, In step (d) above, A core replacement method in which cooling water is filled into the first structural space and the containment vessel, and cooling water is not filled into the second structural space and the second CV space.

10. In Paragraph 5, After the above (e) step, A step of removing the cooling water filled in the space of the first structure; A step of returning the above sealing structure from the second position to the first position; and A core replacement method further comprising the step of joining the head of the reactor vessel (RV) and the head of the containment vessel (CV).

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