Nuclear power plant having improved steam explosion mitigation performance

Abstract

The present invention relates to a nuclear power plant with improved steam explosion mitigation performance, the nuclear power plant comprising: an integrated reactor including a hemispherical first portion inside which a core and a steam generator are positioned and a cylindrical second portion positioned above the first portion; a containment vessel for accommodating the integrated reactor, having a cooling space surrounding the integrated reactor, and including a first containment portion facing the first portion and a second containment portion facing the second portion; and a lower structure which is located in the cooling space and is located under the integrated reactor, wherein the lower structure comprises a first plate and a second plate disposed below the first plate, and the first plate and the second plate are arranged in a horizontal direction and face each other.

Description

Nuclear power plants with improved steam explosion resistance

[0001] The present invention relates to a nuclear power plant with improved steam explosion resistance.

[0002] In the event of a major nuclear power plant accident, the nuclear fuel and surrounding structures within the reactor melt, creating a core melt. This core melt continuously generates heat and releases radioactive fission products, causing massive casualties and property damage. Therefore, the core melt must be cooled quickly and thoroughly to minimize structural damage and the release of radioactive fission products.

[0003] Conventional core-molten external cooling systems, called core catchers, are complex, consisting of a free catcher for collecting core molten material, a core molten material transport channel, and a core molten material distribution and cooling space. Furthermore, their small cross-sectional area and relatively high flow resistance lead to delays in cooling the high-temperature core molten material, making rapid response difficult.

[0004] Another approach, called in-vessel retention, utilizes gravity to fill the reactor vessel with coolant in the event of a severe accident, thereby confining the core material within the reactor. Natural circulation of the coolant cools the outer walls of the reactor vessel, thereby containing the core material. However, this approach is known to have significant uncertainties in practical application, as the heat removal capacity of the outer walls is limited for high-power reactors.

[0005] In high-power reactors, if heat removal through external wall cooling is not sufficient, core melt may penetrate the reactor and be released to the outside due to heat concentration phenomena such as those occurring in the layer of molten metal formed on top of the melt. Since the reactor compartment is already filled with coolant, the contact between the released core melt and the coolant may cause a steam explosion, destroying the reactor compartment or damaging the reactor vessel and related piping, compromising the containment seal and potentially releasing radioactive materials such as fission products outside the containment.

[0006] Accordingly, the purpose of the present invention is to provide a nuclear power plant that can effectively deal with a momentary steam explosion when core melt is ejected outside the reactor vessel and minimize the release of fission products generated in the event of an accident.

[0007] The present invention relates to a nuclear power plant with improved steam explosion resistance, comprising: an integral reactor having a core and a steam generator positioned therein, the integral reactor including a hemispherical first section and a cylindrical second section positioned above the first section; a containment vessel accommodating the integral reactor, the containment vessel having a cooling space surrounding the integral reactor, the containment vessel including a first containment section facing the first section and a second containment section facing the second section; and a lower structure positioned in the cooling space and positioned below the integral reactor, the lower structure including: a first plate; and a second plate positioned below the first plate, the first plate and the second plate being arranged in a horizontal direction and facing each other.

[0008] The integrated reactor may further include a fixing member for fixing the integrated reactor to the containment vessel, and the fixing member may include a first fixing member connecting the first part and the first containment part.

[0009] The above first plate and the above second plate can be fixed to the above first fixing member.

[0010] The first fixed portion may extend in parallel with the extension direction of the second portion.

[0011] The first fixed portion may extend from the boundary between the first portion and the second portion to the first containment portion.

[0012] The above fixed portion may further include a second fixed portion extending from the boundary between the first portion and the second portion to the second containment portion.

[0013] The first plate may be made of a metal material and have a plurality of first through holes formed therein, and the second plate may be made of a metal material less elastic than the first plate and have a plurality of second through holes formed therein, each of which has a smaller penetration area than the first through holes.

[0014] The above containment vessel further includes a basic solid material storage section located in the cooling space, storing a basic solid material that dissolves in the cooling water in the event of an accident and increases the solubility of fission products generated due to damage to the integral reactor, and the basic solid material storage section may be located between the first section and the first containment section.

[0015] The above basic solid material may include at least one of NaOH and Tri-Sodium Phosphate.

[0016] The containment vessel may further include a coating layer formed on at least a portion of the surface of the containment vessel and made of a coating agent of a porous material, which increases the thermal margin of the containment vessel.

[0017] According to the present invention, a nuclear power plant is provided that overcomes the technical limitations of responding to severe accidents in conventional nuclear power plants, improves steam explosion response performance, and minimizes the release of fission products generated in the event of an accident.

[0018] Figure 1 illustrates a nuclear power plant according to one embodiment of the present invention.

[0019] Figure 2 is an enlarged view of A in Figure 1,

[0020] Figure 3 illustrates a first plate among the substructures in a nuclear power plant according to one embodiment of the present invention.

[0021] Figure 4 illustrates a second plate among the substructures in a nuclear power plant according to one embodiment of the present invention.

[0022] Figure 5 illustrates the operation of a nuclear power plant in the event of a major accident according to one embodiment of the present invention.

[0023] The present invention will be described in more detail with reference to the drawings below.

[0024] The attached drawings are merely examples intended to more specifically illustrate the technical concepts of the present invention, and therefore, the scope of the present invention is not limited to the attached drawings. Furthermore, the attached drawings may exaggerate the size and spacing of components to illustrate the relationships between components.

[0025] FIG. 1 illustrates a nuclear power plant according to an embodiment of the present invention, FIG. 2 is an enlarged view of A in FIG. 1, FIG. 3 illustrates a first plate among substructures in a nuclear power plant according to an embodiment of the present invention, and FIG. 4 illustrates a second plate among substructures in a nuclear power plant according to an embodiment of the present invention.

[0026] A nuclear power plant (10) includes an integral reactor (100, small modular reactor, SMR), a containment vessel (200), a substructure (300), and a fixed part (400).

[0027] An integral reactor (100) has a core and a steam generator located inside, and includes a hemispherical first part (110) and a cylindrical second part (120). The second part (120) is located above the first part (110).

[0028] Referring to FIG. 1, the containment vessel (200) accommodates an integral reactor (100) and forms a cooling space (T) surrounding the integral reactor (100).

[0029] The containment vessel (200) includes a first containment section (210), a second containment section (220), a basic solid material storage section (230), and a coating layer (240).

[0030] The first containment portion (210) faces the first portion (110), and the second containment portion (220) faces the second portion (120). The first containment portion (210) is illustrated as a hemisphere, but is not limited thereto.

[0031] The basic solid material storage unit (230) is located in the cooling space (T) and contains a basic solid material inside that increases the solubility of fission products generated by an accident such as a breakdown of the integral reactor (100).

[0032] The basic solid material storage unit (230) may be in the form of a mesh to ensure contact between the basic solid material and the cooling water. In another embodiment, the basic solid material storage unit (230) may be the basic solid material itself, without including a separate storage facility, and the basic solid material may be in the form of a block.

[0033] In one embodiment of the present invention, the basic solid material storage unit (230) is shown as being located in the first containment section (210) facing the first section (110), but is not limited thereto.

[0034] The basic solid substance may be selected from among NaOH and Tri-Sodium Phosphate and used, and is dissolved in the coolant ejected from the integral reactor (100) in the event of an accident to create a basic atmosphere and increase the solubility of fission products dissolved in the coolant.

[0035] Referring to FIG. 2, the coating layer (240) is formed on the surface of the containment vessel (200), is made of a coating agent of a porous material, and increases the thermal margin of the containment vessel (200).

[0036] The coating agent for the porous material may be selected from among activated carbon, zeolite, and bentonite having microporous materials, but is not limited thereto.

[0037] In one embodiment of the present invention, the CO layer (240) may be formed on part or the entirety of the first containment portion (210), and may also be formed on the second containment portion (220) or the first fixing portion (410) described later.

[0038] The containment vessel (200) can be manufactured as a steel structure and is fixed to the concrete structure through a separate containment vessel support structure (K).

[0039] The substructure (300) includes a first plate (310) and a second plate (320).

[0040] The first plate (310) is made of a metal material, and as shown in Fig. 3, a plurality of first through holes (311) are formed therein.

[0041] The second plate (320) is made of a metal material that is less elastic than the first plate (310), and, as shown in FIG. 4, is formed with a plurality of second through holes (321) each having a smaller penetration area than the first through hole (311).

[0042] In another embodiment, the second plate (320) may have less elasticity than the first plate (310) due to differences in plate thickness, etc., together with or separately from differences in metal material.

[0043] The first plate (310) and the second plate (320) are fixed to the first fixing member (410) described later.

[0044] The first plate (310) and the second plate (320) are formed to be wider than the cross-sectional area of ​​the integral reactor (100) and are arranged so that the integral reactor (100) overlaps in the longitudinal direction.

[0045] The first plate (310) is fixed to the first fixing member (410) at a distance of a predetermined distance from the first part (110), and the predetermined distance is 0.1 to 0.5 meters from the lowest point of the first part (110), and preferably, it is fixed to the first fixing member (410) at a distance of 0.3 meters from the first part (110).

[0046] The second plate (320) is fixed to the first fixing member (410) at a distance of a certain distance from the first plate (310), and the distance is 0.1 to 0.5 meters from the first plate (310), and preferably, it is fixed to the first fixing member (410) at a distance of 0.3 meters from the first plate (310).

[0047] The fixed part (400) includes a first fixed part (410) and a second fixed part (420).

[0048] The first fixing part (410) and the second fixing part (420) are structures made of metal and connect the integral reactor (100) and the containment vessel (200), and support the integral reactor (100) so that it stands upright and is fixed to the containment vessel (200).

[0049] The first fixed part (410) connects the first part (110) and the first containment part (210).

[0050] The first fixed portion (410) extends parallel to the extension direction of the second portion (120) and extends from the boundary between the first portion (110) and the second portion (120) to the first containment portion (210). Here, 'parallel' means extending vertically or at an angle of 85 to 95 degrees.

[0051] The second fixed portion (420) extends from the boundary between the first portion (110) and the second portion (120) to the second containment portion (220).

[0052] Referring to FIG. 5, the operation of a nuclear power plant according to an embodiment of the present invention in the event of a major accident will be described.

[0053] Figure 5 illustrates the operation of a nuclear power plant in the event of a major accident according to one embodiment of the present invention.

[0054] If a major accident, such as a breakdown of an integral reactor (100), occurs, the temperature of the core within the integral reactor (100) rises and the pressure of the integral reactor (100) increases. After the pressure rises, coolant in a steam state is discharged into the containment vessel (200) through a discharge valve (not shown) at the top of the integral reactor (100).

[0055] The discharged cooling water condenses in the cooling space (T) and moves downward, and the basic solid material (M) in the basic solid material storage unit (230) is dissolved by this cooling water.

[0056] The basic solid material (M) dissolved in the cooling water contributes to increasing the solubility of the fission products floating inside the cooling space (T). That is, the solubility of the fission products increases under basic conditions through the basic solid material (M), enabling effective management and control of the fission products within the containment vessel (200).

[0057] As illustrated in Fig. 5, when a major accident occurs, the core molten material falling through the lower part of the integral reactor (100) comes into contact with the first plate (310) having a plurality of first penetration holes (311) formed therein.

[0058] At this time, the core molten material is cooled by contact with the first plate (310) and is fragmented into pieces as it passes through the first penetration hole (311). In addition, since the first plate (310) is made of a metal material with higher elasticity than the second plate (320), it serves to alleviate the strong shock wave generated by the ejection of the core molten material falling to the bottom of the integral reactor (100) in the event of an accident.

[0059] Thereafter, the core melt, which falls due to gravity, comes into contact with the second plate (320), which is made of a metal material less elastic than the first plate (310) and has a plurality of second penetration holes (321) formed therein, each having a smaller penetration area than the first penetration hole (311).

[0060] The temperature of the core melt is lowered further by contact with the second plate (320), and secondary fragmentation into smaller grains occurs than the primary fragmentation that occurred while passing through the first penetration hole (311).

[0061] The core molten material falling freely into the containment vessel (200) comes into contact with the coating layer (240).

[0062] The coating layer (240) effectively blocks the heat load generated from the core melt that accumulates at the bottom of the containment vessel (200), and as a result, the soundness of the containment vessel (200) can be secured through the blocking effect of the coating layer (240).

[0063] The above-described examples serve as illustrative examples of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate the potential for various modifications and implementations of the present invention. Therefore, the scope of technical protection of the present invention should be defined by the appended claims.

Claims

1. In nuclear power plants with improved steam explosion response performance, An integral reactor comprising a first hemispherical section having a core and a steam generator located therein and a second cylindrical section located above the first section; A containment vessel that accommodates the integral reactor, has a cooling space surrounding the integral reactor, and includes a first containment portion facing the first portion and a second containment portion facing the second portion; and It is located in the above cooling space and includes a substructure located at the bottom of the integrated reactor, The above substructure is, Plate 1; Including a second plate positioned below the first plate, A nuclear power plant in which the first plate and the second plate are arranged horizontally and face each other.

2. In paragraph 1, It further includes a fixing member for fixing the above-mentioned integral reactor to the above-mentioned containment vessel, The above fixed part, A nuclear power plant including a first fixed section connecting the first section and the first containment section.

3. In paragraph 2, A nuclear power plant in which the first plate and the second plate are fixed to the first fixing member.

4. In paragraph 3, A nuclear power plant in which the first fixed section extends parallel to the extension direction of the second section.

5. In paragraph 4, The above first fixed government, A nuclear power plant extending from the boundary between the first and second sections to the first containment section.

6. In paragraph 5, The above fixed part, A nuclear power plant further comprising a second fixed section extending from the boundary between the first section and the second section to the second containment section.

7. In paragraph 3, The above first plate is made of a metal material and has a plurality of first through holes formed therein. A nuclear power plant in which the second plate is made of a metal material having less elasticity than the first plate, and a plurality of second penetration holes are formed, each having a smaller penetration area than the first penetration hole.

8. In paragraph 1, The above containment vessel is, It further includes a basic solid material storage unit located in the above cooling space, which stores a basic solid material that dissolves in the coolant in the event of an accident and increases the solubility of fission products generated due to damage to the integral reactor. A nuclear power plant in which the basic solid material storage unit is located between the first section and the first containment section.

9. In paragraph 8, A nuclear power plant wherein the basic solid substance comprises at least one of NaOH and Tri-Sodium Phosphate.

10. In paragraph 1, A nuclear power plant further comprising a coating layer formed on at least a portion of the surface of the containment vessel, the coating layer being made of a porous material, and increasing the thermal margin of the containment vessel.

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