A passive containment internal replacement water tank

Abstract

The application provides a non-active containment built-in refueling water tank, which is arranged in the inside of a containment, the containment is sequentially provided with an outer wall, an inner wall and a secondary shielding wall from outside to inside, a circular gap is formed between the inner wall and the secondary shielding wall, the inside space of the secondary shielding wall is used for installing main equipment, and the refueling water tank is arranged in a set region in the circular gap, and the water in the refueling water tank can flood the inside space of the secondary shielding wall to the height of the position of the main pipeline of the main equipment under the action of gravity. The non-active containment built-in refueling water tank is reasonable in layout, the refueling water tank is built-in, so that the influence of the shell function caused by the setting of the containment penetrating pipeline is avoided, and the safety is improved.

Description

Technical Field

[0001] This invention belongs to the field of nuclear industry technology, and specifically relates to a passive containment refueling tank. Background Technology

[0002] Safety is paramount in nuclear power plant design. The fundamental safety functions of a nuclear power plant include reactivity control, residual heat removal from the reactor core, and radioactive material containment. The systems that perform these safety functions are called dedicated safety systems. Compared to active dedicated safety systems, which require extensive safety-level support systems, passive safety systems are simpler to design, do not rely on AC power, and can maintain nuclear power plant safety long-term without active equipment, thus balancing safety and economy. However, designing passive systems as dedicated safety facilities significantly increases the technical difficulty, bringing a series of design concepts and engineering challenges that need to be addressed.

[0003] The passive safety injection system is an important dedicated safety system for removing residual heat from the reactor core. It is used to provide core makeup water in the event of a large break loss-of-coolant (LOCA) accident in a pressurized water reactor nuclear power plant, ensuring that the core is submerged and continuously removing core decay heat, limiting fuel damage and the release of fission products. In the event of a severe accident involving core meltdown, water is injected into the reactor cavity to cool the outer wall of the reactor pressure vessel to prevent the molten core from melting through the reactor pressure vessel, thereby trapping the molten core inside the reactor pressure vessel.

[0004] Passive safety injection systems typically include three water sources: two full-pressure makeup water tanks, two safety injection tanks, and one refueling water tank, which respectively provide core makeup water for the high, medium, and low pressure stages within the pressure vessel. Through the injection of the above water sources, total flooding and long-term cooling of the core and the main piping below the containment can be achieved after an accident.

[0005] Among the three water sources, the refueling tank has the largest water volume and the greatest impact on the containment design. However, the refueling tank has strict requirements for placement. When passive injection is achieved, it needs to be placed above the hot section outlet of the main pipeline. Furthermore, due to the tighter space inside the containment under the three-loop design, there is no space above the equipment inside the containment that meets the requirements. Therefore, there is currently no design scheme for placing a passive total submerged refueling tank inside the containment in the three-loop pressurized water reactor. The tank can only be placed outside the containment, which requires additional through pipelines on the containment, affecting the containment function.

[0006] Although the Hualong One reactor has a reactor cavity flooding pool inside the containment vessel, due to location and space limitations, the height and water volume of this pool can only be used to flood the lower head of the pressure vessel in the event of a severe accident. To achieve complete flooding of the reactor cavity, additional water sources and active equipment are required. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a passive containment refueling tank. The refueling tank has a reasonable layout and is built into the containment, thereby avoiding the impact on the containment function caused by the installation of containment penetration pipelines and improving safety.

[0008] This invention provides a passive containment refueling tank, which is arranged inside the containment. The containment consists of an outer wall, an inner wall, and a secondary shielding wall arranged sequentially from the outside to the inside. A circular gap is formed between the inner wall and the secondary shielding wall. The internal space of the secondary shielding wall is used to install the main equipment. The refueling tank is located within a designated area in the circular gap. In case of an accident, the water in the refueling tank can submerge the internal space of the secondary shielding wall to the height of the main pipeline in the main equipment under the action of gravity.

[0009] Preferably, the bottom height of the designated area is not lower than the height of the main pipe, and the spatial volume of the designated area is not less than the spatial volume below the height of the main pipe in the internal space of the secondary shielding wall.

[0010] Preferably, the main equipment is installed at the lower part of the internal space of the secondary shielding wall, and the ring hoisting equipment is installed at the upper part for hoisting the main equipment. The feed water tanks are distributed vertically in the area between the ring hoisting equipment and the main equipment in the annular gap, so as to avoid the operating space of each piece of equipment.

[0011] Preferably, the ratio between the width of the annular gap where the feed tank is located and the diameter of the secondary shielding wall is 0.24 to 0.27.

[0012] Preferably, the height difference between the bottom surface of the feed tank and the center line of the main pipeline is 25m to 27m.

[0013] Preferably, an equipment gate is provided through the outer wall, inner wall and secondary shielding wall of the shell. The equipment gate is located at the height between the ring hoist and the main equipment, and is used for the main equipment to enter and exit the internal space of the secondary shielding wall. The feed tank is distributed in an arc-shaped strip area in the annular gap. The arc-shaped strip area avoids the area where the equipment gate is located.

[0014] Preferably, a PCS heat exchanger is also provided in the annular gap between the inner wall of the containment shell and the secondary shielding wall, and the feed water tank is located at the same height as the PCS heat exchanger, in an arc-shaped strip area in the annular gap to avoid the PCS heat exchanger.

[0015] Preferably, the main equipment includes a pressure vessel, an evaporator, and the main pipeline. The main pipeline is horizontally connected between the pressure vessel and the evaporator. Multiple evaporators are provided and arranged around the central axis of the containment vessel. The bottom surface of the refueling tank is not lower than the elevation of the evaporator outlet pipeline to avoid space for the arrangement of secondary loop pipelines at the outlet pipeline.

[0016] Preferably, the main equipment further includes a refill water tank, which is located on top of the pressure vessel. The top cover of the pressure vessel extends into the refill water tank through the bottom of the refill water tank. The refill water tank is connected to the refill water tank so that water can be introduced from the refill water tank into the refill water tank before the top cover of the pressure vessel is opened, thereby sealing the pressure vessel.

[0017] This invention provides a passive containment refueling tank, which is installed inside the containment, specifically in the annular gap formed by the inner wall of the containment and the secondary shielding wall. It does not occupy the space of the main equipment installed inside the secondary shielding wall, so the layout of the main equipment in the containment is not further restricted. Moreover, the space where the main equipment and the refueling tank are located is separated by the secondary shielding wall, so the area above the main equipment is not obstructed and will not affect the hoisting of the main equipment. At the same time, the refueling tank is also installed inside the containment, avoiding the installation of through pipelines on the containment that would affect safety.

[0018] The internal refueling tank fully utilizes the fluid properties of water, filling spaces that were originally unsuitable for equipment and could only accommodate small components. This placement not only makes full use of the internal space layout and improves space utilization, but also fills the annular gap formed by the previously empty inner wall of the shell and the secondary shielding wall, further providing support and ensuring good stress performance of the containment. Through a reasonable arrangement method, the passive total submersion refueling tank can be built into the containment, satisfying both containment functions and economic efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the layout structure of the refill tank inside the passive containment in an embodiment of the present invention;

[0020] Figure 2 yes Figure 1 Diagram of the AA direction;

[0021] Figure 3 yes Figure 1 Diagram of the BB direction.

[0022] In the diagram: 1. Inner wall of the shell; 2. Secondary shielding wall; 21. Annular gap; 3. Main equipment; 31. Main pipeline; 32. Pressure vessel; 33. Evaporator; 331. Outlet pipeline; 34. Material exchange water tank; 35. Loading and unloading machine; 4. Material exchange water tank; 5. Ring hoisting equipment; 6. Equipment gate; 7. PCS heat exchanger; 8. Operating platform. Detailed Implementation

[0023] The technical solutions of the invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without creative effort are within the scope of the invention.

[0024] In the description of this invention, it should be noted that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience and simplification of the description and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] In the description of this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Example

[0028] like Figures 1 to 3 As shown, in this embodiment, the refueling water tank 4 is arranged inside the passive containment. The containment is provided with an outer shell, an inner shell 1, and a secondary shielding wall 2 from the outside to the inside. The inner shell 1 is fitted over the secondary shielding wall 2 to form an annular gap 21 between them. The internal space of the secondary shielding wall 2 is used to install the main equipment 3. The refueling water tank 4 is set in a designated area in the annular gap 21. Under accident conditions, the water in the refueling water tank 4 can submerge the internal space of the secondary shielding wall 2 to the height of the main pipeline 31 in the main equipment 3 under the action of gravity.

[0029] In this embodiment, the refueling water tank 4 is located in the annular gap 21 formed by the inner wall 1 of the shell and the secondary shielding wall 2, without occupying the space of the main equipment 3 located inside the secondary shielding wall 2. Therefore, the layout of the main equipment 3 in the shell space is not further restricted. Since the main equipment 3 needs to be hoisted and repaired during the operation of the nuclear power plant, it is not advisable to arrange the water tank within the area inside the secondary shielding wall to avoid affecting the hoisting and ring hoisting operations of the main equipment 3. Therefore, in this embodiment, the space where the main equipment 3 and the refueling water tank 4 are located is separated by the secondary shielding wall 2. The area above the main equipment 3 is not obstructed and will not affect the hoisting of the main equipment 3. At the same time, the refueling water tank 4 is also located inside the containment vessel to avoid the safety being affected by the installation of through pipelines on the shell.

[0030] The internal refueling tank 4 makes full use of the fluid properties of water, filling the space that was originally unsuitable for equipment and could only accommodate small components. This arrangement not only makes full use of the internal space layout and improves space utilization, but also fills the annular gap 21 formed by the originally empty inner wall 1 and secondary shielding wall 2, further providing support and ensuring good stress performance of the containment. Through a reasonable arrangement method, the passive total submersion refueling tank is built into the containment, which satisfies both containment function and economic efficiency.

[0031] In this embodiment, a through-pipeline is installed on the secondary shielding wall 2 to connect the internal space and the refueling water tank 4. A valve is installed on the through-pipeline. In the event of an accident such as a main pipeline rupture, the valve automatically opens upon receiving a signal, allowing water from the refueling water tank 4 to enter the internal space of the secondary shielding wall 2 under gravity to cool the reactor core. In the event of a severe accident such as a meltdown, water can also flood the area below the main pipeline through the through-pipeline under gravity and participate in the cooling cycle within the containment.

[0032] In this embodiment, the bottom height of the designated area is not lower than the height of the main pipe 31, so the water in the refueling tank 4 can flow out completely into the placement space of the main equipment 3 under the action of gravity. The volume of the designated area is not less than the volume of the space below the height of the main pipe 31 in the internal space of the secondary shielding wall 2, so that the water in the refueling tank 4 is sufficient to completely submerge the reactor cavity to the height of the main pipe 31, satisfying the passive requirements and submersion height requirements for heat removal after an accident.

[0033] In this embodiment, the main equipment 3 is installed at the lower part of the internal space of the secondary shielding wall 2, and the ring hoisting equipment 5 is installed at the upper part for hoisting the main equipment 3. The feed water tank 4 is distributed in the vertical direction in the area between the ring hoisting equipment 5 and the main equipment 3 in the annular gap 21, so as to avoid the operating space of each equipment.

[0034] In this embodiment, the ratio between the width of the annular gap 21 where the refueling water tank 4 is located and the diameter of the secondary shielding wall 2 is 0.24 to 0.27. This ratio range ensures that the gap is not too wide, which would affect the equipment layout, while also providing sufficient water storage space for the refueling water tank 4. In this embodiment, the diameter of the secondary shielding wall 2 is 15.8m, so the width of the annular gap 21 is preferably 4m. The height difference between the bottom surface of the refueling water tank 4 and the center line of the main pipeline 31 is 25m to 27m, providing sufficient space between the refueling water tank 4 and the main pipeline 31 to facilitate the layout of other equipment without affecting the hoisting of components. In this embodiment, 26m is preferred.

[0035] In this embodiment, equipment gates 6 are provided through the outer wall of the shell, the inner wall 1 of the shell, and the secondary shielding wall 2. The height of the equipment gates 6 is located between the ring-shaped hoisting equipment 5 and the main equipment 3, allowing the main equipment 3 to enter and exit the internal space of the secondary shielding wall 2. The feed tanks 4 are distributed in the arc-shaped strip area within the annular gap 21. The arc-shaped strip area avoids the area where the equipment gates 6 are located, thus not affecting the arrangement of the equipment gates 6. Figure 2 As shown. In this embodiment, the equipment gate 6 is a sliding door with lifting mechanism. Therefore, the feed tank 4 avoids the area where the equipment gate 6 is located in the entire vertical direction, thereby avoiding affecting the opening and closing operation.

[0036] In this embodiment, a PCS (Passive Containment Heat Transfer System) heat exchanger 7 is also installed in the annular gap 21 between the inner wall 1 of the containment shell and the secondary shielding wall 2. The refueling water tank 4 is located at the same height as the PCS heat exchanger 7, distributed in an arc-shaped strip area within the annular gap 21 that avoids the PCS heat exchanger 7, so as not to affect the arrangement of the PCS heat exchanger 7 and its piping. Figure 3 As shown.

[0037] In this embodiment, the main equipment 3 includes a pressure vessel 32, an evaporator 33, and a main pipeline 31. The main pipeline 31 is connected horizontally between the pressure vessel 32 and the evaporator 33. Multiple evaporators 33 are provided and arranged around the central axis of the containment vessel. The bottom height of the refill water tank 4 is not lower than the elevation of the outlet pipeline 331 of the evaporator 33, so as to avoid the arrangement space of the secondary loop pipeline at the outlet pipeline 331.

[0038] In this embodiment, the main equipment 3 also includes a refueling water tank 34, which is located on top of the pressure vessel 32. The top cover of the pressure vessel 32 extends into the refueling water tank 34 through its bottom. The refueling water tank 34 is connected to the refueling water tank 4, so that water can be introduced from the refueling water tank 4 into the refueling water tank 34 before the top cover of the pressure vessel 32 is opened, thereby sealing the pressure vessel 32. That is, the water in the refueling water tank 4 can also be used as refueling water. During normal refueling, water can be pumped to the refueling water tank 34 (i.e., the in-pile component pool) to meet the water demand of the refueling water tank 34.

[0039] In this embodiment, the main equipment 3 also includes a loading and unloading machine 35, which is installed on the top of the material changing pool 34 and is used to perform material changing operations on the pressure vessel 32, which is closed under the water level of the material changing pool 34, during the opening of the top cover of the pressure vessel 32.

[0040] In this embodiment, the containment also includes an operating platform 8. The top surface of the operating platform 8 is located at the junction of the material exchange pool 34 and the loading and unloading machine 35. The bottom edge of the equipment gate 6 is flush with the operating platform 8 to facilitate the entry and exit of the equipment from the containment.

[0041] The aforementioned material replacement water tank 4 is vertically distributed in the annular gap 21 within the area between the ring-shaped hoisting equipment 5 and the main equipment 3. Specifically, the lowest point of the material replacement water tank 4 is above the elevations of the operating platform 8, the loading and unloading machine 35, and the outlet pipe 331 of the evaporator 33, while the highest point of the material replacement water tank 4 is below the ring-shaped hoisting equipment 5. This position does not affect the arrangement of the main equipment 3 and related pipes below the operating platform 8, nor does it affect the operating space of the loading and unloading machine 35 and the ring-shaped hoisting equipment 5.

[0042] In this embodiment, in the vertical direction, when the secondary shielding wall 2 extends upward from the bottom of the containment to the height of the operating platform 8, it continues to extend upward to the area below the hoisting equipment 5, thus forming the inner wall of the material exchange water tank 4.

[0043] The refueling water tank 4 is located above the operating platform 8. This is because the main equipment 3, main pipeline 31, and other auxiliary systems within the containment are primarily located below the operating platform 8. Placing a large-capacity water tank below the operating platform 8 would significantly impact the arrangement of these items. The arrangement of items above the operating platform 8 is relatively simple, mainly consisting of the equipment gate 6, the loading / unloading machine 35, and the outlet pipeline 331 (i.e., the main steam pipeline). The loading / unloading machine 35 and the main steam pipeline are of similar height and occupy a large sector area (centered on the containment axis), while the upper space is relatively spacious. Therefore, the height of the refueling water tank 4 should be higher than these two devices. Furthermore, the higher the water tank, the greater the gravitational potential energy, and the more reliable the passive injection relying on gravity.

[0044] The equipment gate 6 is quite high, approaching the height of the ring-shaped hoist. If the refill water tank 4 is placed above the equipment gate 6, the water volume that the space can hold will be insufficient to meet the submersion requirements. Furthermore, the fan-shaped area (centered on the containment axis) occupied by the equipment gate 6 is relatively small. Therefore, the refill water tank 5 only needs to be arranged to avoid this fan-shaped area. Ultimately, the refill water tank is located as follows: Figure 1The fan-shaped area above height A, excluding equipment gate 6. The PCS heat exchanger 7 is located at height B and above; therefore, the feed water tank 4 should also avoid the fan-shaped area containing the PCS heat exchanger 7 and its piping above this height.

[0045] The water volume in refueling tank 4 should meet the needs of refueling and reactor core flooding (refueling and accident conditions do not occur simultaneously). During normal refueling at the nuclear power plant, water can be introduced into refueling pool 34 using refueling water pumps. In the event of a severe accident, to ensure timely removal of core heat and prevent core meltdown leading to nuclear leakage, the water in refueling tank 4 will, by gravity, completely flood the area below the main pipeline 31.

[0046] In this embodiment, the refueling tank 4 can achieve passive core submersion by gravity, and can also be used to fill the refueling pool 34 with water during normal refueling of the power plant.

[0047] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A passive containment refueling tank, characterized in that: The refueling tank (4) is arranged inside the containment vessel, and the containment vessel is provided with an outer wall, an inner wall (1) and a secondary shielding wall (2) from the outside to the inside. An annular gap (21) is formed between the inner wall (1) of the shell and the secondary shielding wall (2). The internal space of the secondary shielding wall (2) is used to install the main equipment (3). The refueling water tank (4) is set within a designated area in the annular gap (21). Under accident conditions, the water in the refueling water tank (4) can submerge the internal space of the secondary shielding wall (2) to the height of the main pipeline (31) in the main equipment (3) under the action of gravity. The bottom height of the designated area is not lower than the height of the main pipeline (31), and the spatial volume of the designated area is not less than the spatial volume below the height of the main pipeline (31) in the internal space of the secondary shielding wall (2). The main equipment (3) is installed at the lower part of the internal space of the secondary shielding wall (2), and the ring hoisting equipment (5) is installed at the upper part for hoisting the main equipment (3). The feed tank (4) is distributed vertically in the annular gap (21) in the area between the ring hoisting equipment (5) and the main equipment (3) to avoid the operating space of each equipment; A PCS heat exchanger (7) is also installed in the annular gap (21) between the inner wall (1) of the containment shell and the secondary shielding wall (2). The feed tank (4) is located at the same height as the PCS heat exchanger (7) and is distributed in an arc-shaped strip area in the annular gap (21) to avoid the PCS heat exchanger (7).

2. The passive containment refueling tank according to claim 1, characterized in that: The ratio between the width of the annular gap (21) where the feed tank (4) is located and the diameter of the secondary shielding wall (2) is 0.24~0.

27.

3. The passive containment refueling tank according to claim 1, characterized in that: The height difference between the bottom surface of the refill water tank (4) and the center line of the main pipeline (31) is 25m~27m.

4. The passive containment refueling tank according to claim 1, characterized in that: Equipment gates (6) are provided through the outer wall of the shell, the inner wall of the shell (1), and the secondary shielding wall (2). The equipment gates (6) are located at a height between the ring hoisting equipment (5) and the main equipment (3), and are used for the main equipment (3) to enter and exit the internal space of the secondary shielding wall (2). The feed tank (4) is distributed in an arc-shaped strip area in the annular gap (21), and the arc-shaped strip area avoids the area where the equipment gate (6) is located.

5. The passive containment refueling tank according to claim 1, characterized in that: The main equipment (3) includes a pressure vessel (32), an evaporator (33), and a main pipeline (31), which is horizontally connected between the pressure vessel (32) and the evaporator (33). The evaporators (33) are provided in multiple forms and arranged around the central axis of the containment. The bottom height of the feed tank (4) is not lower than the elevation of the outlet pipe (331) of the evaporator (33) to avoid the arrangement space of the secondary loop pipe at the outlet pipe (331).

6. The passive containment refueling tank according to claim 5, characterized in that: The main equipment (3) also includes a refueling water tank (34), which is located on top of the pressure vessel (32). The top cover of the pressure vessel (32) extends through the bottom of the refueling tank (34) into the refueling tank (34). The refill pool (34) is connected to the refill tank (4) so ​​that water is introduced from the refill tank (4) into the refill pool (34) before the top cover of the pressure vessel (32) is opened, thereby sealing the pressure vessel (32).

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