A lead-cooled nuclear reactor with a technology for mitigating steam generator rupture accidents

Abstract

The present invention provides a lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology, relating to the field of nuclear power technology. The lead-cooled nuclear reactor includes a reactor vessel equipped with a core, a steam generator, and a flow guide assembly. The flow guide assembly has a flow guide cavity with an open top port, into which the lower section of the steam generator extends through the top port. The flow guide assembly includes a vertical baffle, a bottom flow guide, and a vertical flow guide. The vertical baffle is located between the steam generator and the reactor core and is provided with a liquid inlet. The bottom flow guide is located below the steam generator and forms a first flow guide channel with the steam generator. The vertical flow guide is located on the side of the steam generator facing away from the reactor core and forms a second flow guide channel with the steam generator. A liquid outlet is formed above the vertical flow guide, and a third flow guide channel is formed with the side wall of the reactor vessel. The flow guide assembly in the lead-cooled nuclear reactor has a simple structure, low cost, and low flow resistance. It can effectively degas the coolant and ensure the convenient layout of the steam generator.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and particularly relates to a lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology. Background Art

[0002] A lead-cooled fast reactor is a fast neutron reactor that uses liquid metal lead or lead-bismuth alloy as a coolant, and has good inherent safety, thermal-hydraulic and neutron physics characteristics. It can be used for nuclear fuel breeding and long-lived fission product transmutation, and is of great significance to the sustainable development of nuclear energy.

[0003] The frequently occurring steam generator tube rupture (SGTR) accident (also known as the lead-water reaction accident) is considered to be one of the key problems restricting the development of lead-cooled fast reactors. Among them, the steam generator tube rupture accident causes bubbles to follow the liquid metal into the core and leads to core power fluctuations or even core melting. The conventional degassing structure has a weak degassing effect on liquid metal, and the degassing structure is complex, costly, has a large flow resistance, and will increase the layout difficulty of the steam generator, and is not suitable for deployment in lead-cooled fast reactors. Summary of the Invention

[0004] The purpose of the present invention is to provide a lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology to solve the technical problems that the existing degassing structure has a weak degassing effect on liquid metal, and the degassing structure is complex, costly, has a large flow resistance, and will increase the layout difficulty of the steam generator.

[0005] To solve the above problems, the present invention provides a lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology, including a reactor vessel with a coolant accommodated in a lower region. A core, a steam generator and a diversion assembly are provided in the reactor vessel. The diversion assembly has a diversion cavity with an open top port. The lower section of the steam generator extends into the diversion cavity through the top port. Among them, the diversion assembly includes:

[0006] A vertical baffle located between the steam generator and the core, with the top end higher than the coolant and provided with an inlet for the coolant to flow into the steam generator;

[0007] A bottom diversion plate located below the steam generator and forming a first diversion channel for the coolant to flow between the bottom diversion plate and the steam generator; and,

[0008] A vertical diversion plate located on the side of the steam generator away from the core. A second diversion channel for the coolant to flow upward is formed between the vertical diversion plate and the steam generator, and an outlet for the coolant to flow out is formed above. And a third diversion channel for the coolant to flow downward is formed between the vertical diversion plate and the side wall of the reactor vessel.

[0009] Optionally, the diversion cavity is annular and disposed around the outer periphery of the reactor core; there are multiple steam generators, and the multiple steam generators are circumferentially arranged around the outer periphery of the reactor core, and the lower segments of the multiple steam generators all extend into the diversion cavity through the top ports.

[0010] Optionally, the second diversion channel is provided with a flow disturbing member, and the flow disturbing member can disturb the coolant flowing through.

[0011] Optionally, the flow disturbing member includes spiral guide vanes extending spirally upward from bottom to top.

[0012] Optionally, the spiral guide vanes are located in the area where the second diversion channel intersects the first diversion channel.

[0013] Optionally, the top end of the vertical guide plate is connected with a horizontal flow buffering plate. There are openings for the coolant to flow between the horizontal flow buffering plate and both the steam generator and the reactor vessel, and in the direction away from the reactor core, the plate area of the horizontal flow buffering plate gradually increases.

[0014] Optionally, in the direction away from the steam generator, the horizontal flow buffering plate includes a first flow buffering plate area and a second flow buffering plate area. Among them, the first flow buffering plate area is located on the side of the vertical guide plate facing the steam generator, and the second flow buffering plate area is located on the side of the vertical guide plate facing away from the steam generator.

[0015] Optionally, a bubble collection structure is provided above the horizontal flow buffering plate, and the bubble collection structure is used to collect the bubbles in the coolant flowing through the corresponding area.

[0016] Optionally, the bubble collection structure includes multiple collecting vertical rods arranged in parallel. The collecting vertical rods are made of a material that is sparse in coolant and hydrophilic to bubbles, and the bottom ends of the collecting vertical rods extend downward into the coolant, and the top ends extend upward out of the coolant.

[0017] Optionally, the flow rate range of the coolant flowing through the steam generator is 0.1 m / s to 0.25 m / s.

[0018] In the lead-cooled nuclear reactor provided by the present invention, the arrangement of the flow guiding assembly, on the one hand, can form a first flow guiding channel, a second flow guiding channel and a third flow guiding channel for guiding the coolant. Among them, the first flow guiding channel can guide the coolant with entrained bubbles away from the reactor core to reduce the entry of bubbles into the reactor core; the second flow guiding channel can guide the coolant with entrained bubbles to move upward, so that the bubbles can more easily move upward and break away from the coolant and enter the gas cavity. The third flow guiding channel increases the flow travel of the coolant, so that the entrained bubbles with upward movement speed can continue to move upward and break away from the coolant and enter the gas cavity, thereby realizing effective degassing treatment of the coolant and reducing the occurrence of reactor core power fluctuations or even meltdown accidents caused by bubbles entering the reactor core. On the other hand, the flow guiding assembly only includes a bottom flow guiding plate extending approximately horizontally and vertical baffles and vertical flow guiding plates extending vertically. The structure is simple, the cost is low, the flow resistance is small, the driving load requirement for the driving pump is correspondingly low, the maintenance requirement is low, and the safety is relatively high. At the same time, both the vertical baffle and the vertical flow guiding plate of the flow guiding assembly are vertical plates, and the lower section of the steam generator can extend downward into the flow guiding cavity through the open top port at the top of the flow guiding assembly, that is, the arrangement of the flow guiding assembly has no influence on the original installation arrangement of the steam generator, thus ensuring the convenience of the installation arrangement of the steam generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a front internal view of the lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology provided by the embodiment of the present invention in the first form;

[0021] Figure 2 It is a front internal view of the lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology provided by the embodiment of the present invention in the second form;

[0022] Figure 3 It is a top internal view of the lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology provided by the embodiment of the present invention in the second form;

[0023] Figure 4 For Figure 3 It is a schematic diagram of the lead-cooled nuclear reactor after removing the horizontal flow retarder and the bubble collection structure.

[0024] Description of the reference numerals:

[0025] 100 - Heap container; 110 - Gas cavity; 120 - Molten pool; 200 - Coolant; 300 - Reactor core; 400 - Steam generator; 500 - Flow - guiding assembly; 50A - Flow - guiding cavity; 510 - Top port; 520 - Vertical baffle; 521 - Liquid inlet; 530 - Bottom flow - guiding plate; 53A - First flow - guiding channel; 540 - Vertical flow - guiding plate; 54A - Second flow - guiding channel; 54B - Third flow - guiding channel; 600 - Turbulence - generating member; 700 - Horizontal flow - damping plate; 710 - First flow - damping plate area; 720 - Second flow - damping plate area; 70A - Opening; 70B - Horizontal flow - damping area; 800 - Bubble collection structure; 810 - Collection vertical rod. Detailed implementation mode

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0029] This embodiment provides a lead - cooled nuclear reactor with a steam generator rupture accident mitigation technology, as Figure 1 and Figure 2As shown, it includes a reactor vessel 100 with a coolant 200 accommodated in a lower region. A reactor core 300, a steam generator 400, and a flow guiding assembly 500 are provided in the reactor vessel 100. The flow guiding assembly 500 has a flow guiding cavity 50A with an open top port 510. The heat transfer tubes at the lower section of the steam generator 400 extend into the flow guiding cavity 50A through the top port 510. Among them, the flow guiding assembly 500 includes a vertical baffle 520, a bottom flow guiding plate 530, and a vertical flow guiding plate 540. The vertical baffle 520 is located between the steam generator 400 and the reactor core 300. The top end of the vertical baffle 520 is higher than the coolant 200, and a liquid inlet 521 for the coolant 200 to flow into the steam generator 400 is provided. The bottom flow guiding plate 530 is located below the steam generator 400, and a first flow guiding channel 53A for the coolant 200 to flow is formed between the bottom flow guiding plate 530 and the steam generator 400. The vertical flow guiding plate 540 is located on the side of the steam generator 400 away from the reactor core 300. A second flow guiding channel 54A for the coolant 200 to flow upward is formed between the vertical flow guiding plate 540 and the steam generator 400. The upper part of the vertical flow guiding plate 540 is lower than the coolant 200 to form a liquid outlet for the coolant 200 to flow out, and a third flow guiding channel 54B for the coolant 200 to flow downward is formed between the vertical flow guiding plate 540 and the side wall of the reactor vessel 100.

[0030] In the lead-cooled nuclear reactor provided in this embodiment, as Figure 1 and Figure 2As shown in the figure, the internal space of the reactor vessel 100 is divided into an upper region and a lower region in the vertical direction, and into a middle region and an outer ring region surrounding the middle region in the radial direction. Among them, the lower region serves as the molten pool 120 and contains the coolant 200, and the upper region serves as the gas cavity 110; the reactor core 300 is located in the middle region of the reactor vessel 100 and is immersed in the coolant 200, and the steam generator 400 is located in the outer ring region of the reactor vessel 100, and the lower heat exchange section of the steam generator 400 extends downward into the coolant 200; the flow guiding assembly 500 serving as a degassing structure is box-shaped and includes a box bottom plate and box side plates provided at the edge of the box bottom plate and extending vertically upward. The lower section of the steam generator 400 extends into it through the top port 510 of the top end of the flow guiding cavity 50A. In the flow guiding assembly 500, the box side plate located between the steam generator 400 and the reactor core 300 serves as the vertical baffle 520, and the vertical baffle 520 extends vertically upward above the liquid level of the coolant 200; the box side plate located on the side of the steam generator 400 away from the reactor core 300 serves as the vertical flow guiding plate 540, and the vertical flow guiding plate 540 extends vertically and its top end is lower than the liquid level of the coolant 200. At the same time, there are intervals between the vertical flow guiding plate 540 and the side walls of the steam generator 400 and the reactor vessel 100 respectively, so as to form a second flow guiding channel 54A between the vertical flow guiding plate 540 and the steam generator 400 and a third flow guiding channel 54B between the vertical flow guiding plate 540 and the side wall of the reactor vessel 100; the box bottom plate is connected between the bottom ends of the vertical baffle 520 and the vertical flow guiding plate 540. The box bottom plate serves as the bottom flow guiding plate 530 and is located below the steam generator 400, and the box bottom plate is spaced from the steam generator 400 to form a first flow guiding channel 53A.

[0031] During use, as Figure 1As shown by the dashed arrow in the figure, under the driving action, the coolant 200 flows upward through the core 300 from bottom to top for heat exchange with it. The coolant 200 that absorbs heat flows out of the core 300 upward and flows into the steam generator 400 through the liquid inlet 521 on the vertical baffle 520. Subsequently, the coolant 200 flows downward through the steam generator 400 to transfer heat to the working medium in the steam generator 400. After transferring heat, the coolant 200 flows downward from the lower end of the steam generator 400 into the flow guiding assembly 500, and then under the guiding action of the bottom flow guiding plate 530, it flows along the first flow guiding channel 53A away from the core 300. When the coolant 200 flows to the end of the first flow guiding channel 53A, it then flows upward along the second flow guiding channel 54A under the guiding action of the vertical flow guiding plate 540. Continuing, when the coolant 200 flows upward to the top of the second flow guiding channel 54A, it turns and flows through the liquid outlet formed above the vertical flow guiding plate 540 into the third flow guiding channel 54B, and then flows downward along the third flow guiding channel 54B under the combined guiding action of the vertical flow guiding plate 540 and the side wall of the reactor vessel 100. Subsequently, the coolant 200 flows downward past the lower part of the flow guiding assembly 500 and reaches the bottom of the core 300, and then flows upward into the core 300 again to achieve cyclic heat exchange.

[0032] When a rupture accident occurs in the heat transfer tubes at the lower section of the steam generator 400, causing bubbles to enter the coolant 200, the smaller bubbles are subject to a smaller buoyancy force and a larger drag force of the coolant 200, so they flow with the coolant 200. Specifically, the bubbles first move away from the core 300 along the first flow guiding channel 53A with the coolant 200 to reduce the entry of bubbles into the core 300. Subsequently, the bubbles enter the second flow guiding channel 54A with the coolant 200 and flow upward. During this process, the bubbles are simultaneously subject to the upward buoyancy force and drag force of the coolant 200, which makes it easier for the bubbles to move upward and break away from the coolant 200 and enter the gas cavity 110. Continuing, for the bubbles that have not broken away from the coolant 200 in the second flow guiding channel 54A, at the initial stage when they enter the third flow guiding channel 54B with the coolant 200 and flow downward along it, the bubbles still have an upward movement speed and continue to move upward to break away from the coolant 200 and enter the gas cavity 110, thereby achieving effective degassing treatment of the coolant 200 and reducing the occurrence of accidents such as power fluctuations or even meltdown in the core 300 caused by bubbles entering the core 300.

[0033] In the lead-cooled nuclear reactor provided in this embodiment, the arrangement of the flow guiding assembly 500 can, on the one hand, form a first flow guiding channel 53A, a second flow guiding channel 54A, and a third flow guiding channel 54B for guiding the coolant 200. Among them, the first flow guiding channel 53A can guide the coolant 200 with entrained bubbles away from the reactor core 300 to reduce the entry of bubbles into the reactor core 300; the second flow guiding channel 54A can guide the coolant 200 with entrained bubbles to move upward, so that the bubbles can more easily move upward and break away from the coolant 200 and enter the gas cavity 110. The third flow guiding channel 54B increases the flow travel of the coolant 200, so that the entrained bubbles with an upward movement speed can continue to move upward and break away from the coolant 200 and enter the gas cavity 110, thereby realizing effective degassing treatment of the coolant 200 and reducing the occurrence of power fluctuations or even meltdown accidents in the reactor core 300 caused by bubbles entering the reactor core 300. On the other hand, the flow guiding assembly 500 only includes a bottom flow guiding plate 530 extending approximately horizontally, a vertical baffle 520, and a vertical flow guiding plate 540 extending vertically. The structure is simple, the cost is low, and the flow resistance is small. Correspondingly, the driving load requirement for the driving pump is low, the maintenance requirement is low, and the safety is relatively high. At the same time, both the vertical baffle 520 and the vertical flow guiding plate 540 of the flow guiding assembly 500 are vertical plates. The lower section of the steam generator 400 can extend downward into the flow guiding cavity 50A through the open top port 510 at the top of the flow guiding assembly 500, that is, the arrangement of the flow guiding assembly 500 has no influence on the original installation arrangement of the steam generator 400, thereby ensuring the installation convenience of the steam generator 400.

[0034] Specifically, the coolant 200 of the lead-cooled nuclear reactor can adopt liquid metal lead or lead-bismuth alloy.

[0035] In this embodiment, as Figures 2 - 4As shown, the diversion cavity 50A is annular and disposed around the outer periphery of the reactor core 300; there are multiple steam generators 400, and the multiple steam generators 400 are circumferentially arranged around the outer periphery of the reactor core 300, and the lower segments of the multiple steam generators 400 extend into the diversion cavity 50A through the top ports 510. The multiple steam generators 400 are circumferentially spaced apart along the outer ring area in the reactor vessel 100 to improve the heat exchange effect with the coolant 200; the diversion assembly 500 is arranged in the shape of an annular box. Specifically, the diversion assembly 500 includes an annular box bottom plate and two annular box side plates. The box bottom plate serves as the bottom diversion plate 530 and is located below the multiple steam generators 400 at the same time, so as to form a first diversion channel 53A between each steam generator 400; one of the box side plates is correspondingly connected to the inner ring edge of the box bottom plate and extends vertically upward. This box side plate serves as the vertical baffle 520 and can simultaneously block between the reactor core 300 and the multiple steam generators 400; the other box side plate is correspondingly connected to the outer ring edge of the box bottom plate and extends vertically upward. This box side plate serves as the vertical diversion plate 540 and is disposed around the side wall of the reactor vessel 100 and the multiple steam generators 400, so as to form a second diversion channel 54A between each steam generator 400, and at the same time form a third diversion channel 54B corresponding to the multiple steam generators 400 between the side wall of the reactor vessel 100 and the multiple steam generators 400.

[0036] In this embodiment, by setting the diversion assembly 500 as a simple annular member, the diversion and degassing functions of the coolant 200 output by the multiple steam generators 400 can be realized simultaneously, thereby further improving the structural simplicity and layout convenience of the degassing structure, reducing the cost and resistance of the degassing structure; in addition, the annular diversion assembly 500 divides the hot and cold regions of the molten pool 120 into two different regions, and can also effectively reduce the thermal stratification effect of the lead-cooled nuclear reactor, making it have strong engineering applicability.

[0037] Among them, Figures 2 - 4 the number of the steam generators 400 in

[0038] is schematically shown as 8, which is not a limitation.

[0039] In this embodiment, as Figures 1 - 4As shown, a spoiler 600 is provided in the second diversion channel 54A, and the spoiler 600 can disrupt the flow of the coolant 200 passing through it. When the coolant 200 carrying bubbles flows upward along the second diversion channel 54A and passes through the spoiler 600, the spoiler 600 can disrupt the flow of the coolant 200, so as to intensify the collision and coalescence of the bubbles in the coolant 200. Correspondingly, the mutually colliding bubbles can merge into larger bubbles, so that the buoyancy force received by the bubbles increases, and then it is easier to move upward and break away from the coolant 200 and enter the gas cavity 110, thereby further improving the degassing effect on the coolant 200 and further reducing the adverse effects caused by the bubbles entering the core 300.

[0040] Specifically, in this embodiment, the spoiler 600 includes spiral guide vanes extending spirally from bottom to top. When the coolant 200 carrying bubbles enters the second diversion channel 54A and flows upward through the spiral guide vanes, it can flow upward in a spiral shape under the guiding action of the spiral guide vanes. Due to the large density difference between the coolant 200 and the bubbles, during the process of the coolant 200 carrying bubbles flowing upward in a spiral shape, it will cause the bubbles to gather towards the center of rotation of the spiral fluid, thereby enhancing the collision and coalescence of the bubbles; at the same time, in the rotating flow field, the pressure distribution is mainly determined by the centrifugal force, and the centrifugal force is outward, so the pressure increases outward from the center of rotation accordingly, that is, the pressure at the center of rotation is lower, and the bubbles located at the center of rotation expand and are more likely to merge, so that the mutually colliding bubbles can merge into larger bubbles, the buoyancy force received by the large bubbles increases, the upward movement speed is faster, and it is easier to break away from the coolant 200 upward and enter the gas cavity 110, thereby further improving the degassing effect of the degassing structure on the coolant 200. Moreover, the spiral guide vane structure is simple, the installation convenience is high, and the flow resistance to the coolant 200 is small.

[0041] Among them, during the process of the bubbles flowing upward in a spiral shape along with the coolant 200, the calculation formula of the centrifugal force received by the bubbles is as follows:

[0042] (Equation 1);

[0043] In Equation 1, F c is the centrifugal force received by the bubbles, and the unit is N; ρ lm is the density of the coolant, and the unit is kg / m 3 ; ρ b is the density of the bubbles, and the unit is kg / m 3 ; u θ is the tangential velocity component of the coolant (coolant rotation speed), and the unit is m / s; r is the rotation radius of the position where the bubbles are located, and the unit is m; V b is the volume of the bubbles, and the unit is m 3。

[0044] In this embodiment, as shown in Figure 1 and Figure 2 , the spiral guide vane is located in the area where the second diversion channel 54A intersects the first diversion channel 53A. The spiral guide vane is located at the bottom area of the second diversion channel 54A. The coolant 200 flowing out of the first diversion channel 53A first flows into the spiral guide vane, and under its guiding action, a fluid flowing upward in a spiral shape is formed. The relatively long channel section of the second diversion channel 54A above the spiral guide vane serves as the flow channel for this spiral fluid, thereby extending the flow path of the spiral fluid, correspondingly extending the collision and coalescence time of the bubbles in the spiral central area, making the effect of the bubbles colliding and coalescing into large bubbles more sufficient, and further increasing the amount of bubbles that detach upward from the coolant 200 and enter the gas cavity 110, and further improving the degassing effect of the degassing structure on the coolant 200.

[0045] In this embodiment, as shown in Figures 1 - 3 , the top end of the vertical guide plate 540 is connected with a horizontal flow retarder plate 700. There are openings 70A for the coolant 200 to flow between the horizontal flow retarder plate 700 and both the steam generator 400 and the reactor vessel 100, and along the direction away from the reactor core 300, the plate area of the horizontal flow retarder plate 700 gradually increases. The horizontal flow retarder plate 700 is located at the bottom end of the liquid outlet. The coolant 200 after degassing treatment through the second diversion channel 54A entraining the remaining bubbles turns through the top opening 70A and flows to above the horizontal flow retarder plate 700, and flows along the horizontal flow retarder plate 700 away from the reactor core 300. And as the plate area of the horizontal flow retarder plate 700 increases, the flow rate of the coolant 200 gradually decreases, thereby forming a horizontal slow flow area 70B with a relatively small speed above the horizontal flow retarder plate 700, correspondingly reducing the drag force of the coolant 200 on the bubbles, and at the same time ensuring that the bubbles entering this area can enter the gas cavity 110 with a relatively small upward travel, and further promoting the bubbles entering this area to be able to break away from the capture of the coolant 200 and enter the gas cavity 110 upward, further improving the degassing effect on the coolant 200.

[0046] Wherein, when the diversion assembly 500 is an annular part, the horizontal flow retarder plate 700 correspondingly extends circumferentially along the annular vertical guide plate 540 to form an annular horizontal plate.

[0047] In this embodiment, as shown in Figure 1 and Figure 3As shown in the figure, along the direction away from the steam generator 400, the horizontal flow baffle 700 includes a first flow baffle area 710 and a second flow baffle area 720. Among them, the first flow baffle area 710 is located on the side of the vertical flow guide plate 540 facing the steam generator 400, and the second flow baffle area 720 is located on the side of the vertical flow guide plate 540 facing away from the steam generator 400. On the one hand, while ensuring the circulation of the coolant 200 between the second flow guide channel 54A and the third flow guide channel 54B, the horizontal flow baffle 700 can effectively increase the flow baffle area of the horizontal flow baffle 700, thereby enhancing the flow baffle effect of the horizontal flow baffle 700 on the coolant 200, and correspondingly further ensuring the degassing effect when the coolant 200 flows through the horizontal flow baffle area 70B. On the other hand, the first flow baffle area 710 extends towards the steam generator 400 above the second flow guide channel 54A, causing a certain blockage above the second flow guide channel 54A, thereby reducing the channel outlet area at the top of the second flow guide channel 54A. When the coolant 200 flows upward through the second flow guide channel 54A to its top channel outlet, the flow area decreases, and the flow velocity correspondingly increases. The upward flow velocity of the bubbles entrained therein also increases, thereby further improving the ability of the bubbles to separate upward from the coolant 200 at the channel outlet and then flow to the horizontal flow baffle area 70B and enter the gas cavity 110, and correspondingly further improving the degassing effect on the coolant 200.

[0048] In this embodiment, as Figures 1 - 3 shown, a bubble collection structure 800 is provided above the horizontal flow baffle 700. The bubble collection structure 800 is used to collect the bubbles in the coolant 200 flowing through the area where it is located. The bubble collection structure 800 extends downward into the coolant 200 above the horizontal flow baffle 700. During the process of the coolant 200 flowing through the horizontal flow baffle area 70B above the horizontal flow baffle 700, when the bubbles entrained therein collide with the bubble collection structure 800, they can be collected by the bubble collection structure 800 and move upward along the bubble collection structure 800 under the action of buoyancy to separate from the coolant 200 and enter the gas cavity 110, thereby further improving the degassing effect on the coolant 200.

[0049] Specifically, in this embodiment, as Figures 1 - 3As shown, the bubble collection structure 800 includes a plurality of parallel and spaced vertical collection rods 810. The vertical collection rods 810 are made of a material that is repellent to the coolant 200 and repellent to the bubbles. The bottom ends of the vertical collection rods 810 extend downward into the coolant 200, while the top ends extend upward out of the coolant 200. The material of the vertical collection rods 810 is determined according to the types of the coolant 200 and the bubbles. When the coolant 200 flows through the horizontal slow flow area 70B, the coolant 200 can flow around the vertical collection rods 810, and the bubbles entrained therein are easily adsorbed by the vertical collection rods 810. Under the upward pull of buoyancy and the upward guidance of the vertical collection rods 810, the bubbles move upward, detach from the coolant 200, and enter the air cavity 110, thereby achieving the bubble collection function of the bubble collection structure 800. In addition, impurities entrained in the coolant 200 can be adsorbed by the vertical collection rods 810 when they flow through and contact the vertical collection rods 810, thereby achieving the collection and cleaning of impurities in the coolant 200. Specifically, a plurality of collecting vertical rods 810 are arranged in a staggered manner to ensure effective contact between the collecting vertical rods 810 and the coolant 200, and accordingly ensure effective collection of bubbles and impurities in the coolant 200 by the bubble collecting structure 800; wherein, Figures 1 - 3 The number and arrangement of the collecting vertical bars 810 are for illustration only and are not intended to be limiting.

[0050] Specifically, the coolant 200 is liquid lead or liquid lead-bismuth alloy, and when the bubbles are water vapor bubbles, the collecting vertical rods 810 can be made of SiC material to achieve the effect of capturing the bubbles.

[0051] In this embodiment, the flow rate of the coolant 200 flowing through the steam generator 400 ranges from 0.1 m / s to 0.25 m / s. The coolant 200 enters the steam generator 400 through the liquid inlet 521 and flows downward through the steam generator 400. When a heat transfer tube of the steam generator 400 ruptures, the bubbles generated by the rupture first enter the coolant 200 flowing therethrough. In this embodiment, the velocity of the coolant 200 flowing through the steam generator 400 is reduced to 0.1 m / s to 0.25 m / s, thereby effectively reducing the coolant 200's ability to capture bubbles and correspondingly enhancing the ability of bubbles to float upward and escape from the coolant 200. This allows more bubbles to escape from the coolant 200 and enter the air cavity 110 during this process, thereby reducing the likelihood of bubbles being entrained into the core 300 and adversely affecting it.

[0052] The drag force generated by the coolant 200 on the bubbles can represent the ability of the coolant 200 to capture the bubbles. The drag force is calculated as follows:

[0053] (Formula 2);

[0054] In formula 2, F d is the drag force exerted by the coolant on the bubble, in N; Cd is the drag coefficient, dimensionless; ρ lm is the density of the coolant, in kg / m 3 ; u is the difference between the coolant and the bubble flow velocities, in m / s; A is the projected area of the bubble in the flow direction, in m 2 .

[0055] As can be seen from Equation 2, the greater the flow velocity of the coolant 200, the greater the difference u between the coolant 200 and the bubble flow velocity. Correspondingly, the greater the drag force exerted by the coolant 200 on the bubble, the stronger the ability of the coolant 200 to capture the bubble, and the weaker the ability of the bubble to detach from the coolant 200. In this embodiment, by reducing the flow velocity of the coolant 200, the ability of the coolant 200 to capture the bubble is reduced, and correspondingly, the ability of the bubble to float upward and detach from the coolant 200 is enhanced, thereby improving the degassing effect of the coolant 200.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lead-cooled nuclear reactor with a steam generator rupture accident mitigation technology, characterized in that A reactor vessel (100) with a lower region accommodating a coolant (200), a reactor core (300), a steam generator (400), and a flow guiding assembly (500) are provided inside the reactor vessel (100). The flow guiding assembly (500) has a flow guiding cavity (50A) with an open top port (510). The lower section of the steam generator (400) extends into the flow guiding cavity (50A) through the top port (510). Among them, the flow guiding assembly (500) includes: A vertical baffle (520), located between the steam generator (400) and the reactor core (300), with its top end higher than the coolant (200), and having an inlet (521) for the coolant (200) to flow into the steam generator (400); A bottom flow guiding plate (530), located below the steam generator (400), and forming a first flow guiding channel (53A) for the coolant (200) to flow between it and the steam generator (400); and, A vertical flow guiding plate (540), located on the side of the steam generator (400) away from the reactor core (300). A second flow guiding channel (54A) for the coolant (200) to flow upward is formed between the vertical flow guiding plate (540) and the steam generator (400). An outlet for the coolant (200) to flow out is formed above. And a third flow guiding channel (54B) for the coolant (200) to flow downward is formed between the vertical flow guiding plate (540) and the side wall of the reactor vessel (100); Among them, the second flow guiding channel (54A) is provided with a flow disturbing member (600), and the flow disturbing member (600) can disturb the coolant (200) flowing through; The top end of the vertical flow guiding plate (540) is connected with a horizontal flow buffering plate (700). Openings (70A) for the coolant (200) to flow are left between the horizontal flow buffering plate (700) and both the steam generator (400) and the reactor vessel (100). And along the direction away from the reactor core (300), the plate surface area of the horizontal flow buffering plate (700) gradually increases. A bubble collecting structure (800) is provided above the horizontal flow buffering plate (700). The bubble collecting structure (800) is used to collect bubbles in the coolant (200) flowing through the corresponding area. And the bubble collecting structure (800) includes a plurality of collecting vertical rods (810) arranged side by side. The collecting vertical rods (810) are made of a material that is hydrophobic to the coolant (200) and hydrophilic to bubbles. And the bottom end of the collecting vertical rod (810) extends downward into the coolant (200), and the top end extends upward out of the coolant (200).

2. The lead-cooled nuclear reactor according to claim 1, characterized in that, The flow guiding cavity (50A) is annular and is arranged around the outer circumference of the reactor core (300); There are a plurality of steam generators (400). The plurality of steam generators (400) are arranged around the outer circumference of the reactor core (300) in the circumferential direction, and the lower sections of the plurality of steam generators (400) all extend into the flow guiding cavity (50A) through the top port (510).

3. The lead-cooled nuclear reactor according to claim 1, characterized in that, The spoiler (600) includes spiral guide vanes extending spirally from bottom to top.

4. The lead-cooled nuclear reactor according to claim 3, wherein, The spiral guide vanes are located in the area where the second diversion channel (54A) intersects the first diversion channel (53A).

5. The lead-cooled nuclear reactor according to claim 1, wherein In the direction away from the steam generator (400), the horizontal flow spoiler (700) includes a first flow spoiler area (710) and a second flow spoiler area (720), wherein the first flow spoiler area (710) is located on the side of the vertical guide plate (540) facing the steam generator (400), and the second flow spoiler area (720) is located on the side of the vertical guide plate (540) facing away from the steam generator (400).

6. The lead-cooled nuclear reactor according to claim 1 or 2, characterized in that, The flow rate range of the coolant (200) flowing through the steam generator (400) is 0.1 m / s to 0.25 m / s.

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