Pressurized water reactor suppression and recirculation backflow integrated system and use method

Abstract

The invention discloses a pressurized water reactor suppression and recirculation backflow integrated system and a use method, the pressurized water reactor suppression and recirculation backflow integrated system comprises a pressure suppression container and a shared flow channel formed by at least one fluid channel, and the shared flow channel is respectively communicated with the pressure suppression container and an internal space of a containment; wherein the shared flow channel is configured as follows: at the initial stage of an accident, a gas-phase medium in the internal space of the containment vessel is guided to the pressure suppression container, so that pressure suppression is realized; in the later period of the accident, the liquid-phase medium in the inner space of the containment vessel is guided to the pressure suppression vessel to serve as a water source for coolant recirculation. According to the invention, the pressure suppression container is provided with a shared flow channel which is also used as a pressure suppression channel of a gas-phase medium and a recirculation backflow channel of a liquid-phase medium, so that integration of a containment pressure suppression function and a recirculation backflow safety injection / containment spraying function after a reactor mass energy release accident is realized, and the space occupied by equipment is reduced; the compactness and the integration degree of the system are improved, and meanwhile the system cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor safety system technology, and in particular to an integrated system for pressurized water reactor suppression and recirculation, and its usage method. Background Technology

[0002] In the safety system design of pressurized water reactor nuclear power plants, the containment vessel, as the last physical barrier, is of paramount importance in terms of its integrity. When a loss-of-coolant accident occurs, such as a reactor coolant pipe rupture, the high-temperature and high-pressure coolant will be released into the containment vessel in the form of steam, causing a sharp rise in the internal temperature and pressure of the containment vessel and threatening its integrity.

[0003] Current safety system designs for large pressurized water reactors utilize dedicated safety systems such as passive containment heat removal systems and containment spray systems to achieve containment pressure control. In the event of a breach accident, reactor coolant and safety injection water flowing out of the breach are channeled through a dedicated return channel within the reactor building into the refueling tank inside the containment to maintain the water supply for primary loop safety injection and containment spray during the long-term recirculation phase after the accident.

[0004] For small pressurized water reactors, the limited space required for their layout and the need to configure dedicated safety systems such as passive containment heat removal systems and containment spray systems result in large equipment footprints, high system complexity, and high costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an integrated system for pressurized water reactor suppression and recirculation, and a method for using it.

[0006] The technical solution adopted by the present invention to solve its technical problem is: to construct an integrated system for pressurized water reactor pressure suppression and recirculation, including a pressure suppression vessel and a shared flow channel formed by at least one fluid channel, wherein the shared flow channel is respectively connected to the internal space of the pressure suppression vessel and the containment vessel; The shared flow channel is configured to: in the early stage of an accident, guide the gaseous medium inside the containment to the pressure suppression container to achieve pressure suppression; and in the later stage of an accident, guide the liquid medium inside the containment to the pressure suppression container as a water source for coolant recirculation.

[0007] Furthermore, the shared flow channel includes at least two suppression inlets with different triggering conditions for responding to different accident conditions.

[0008] Furthermore, at least two of the pressure suppression inlets include a passive inlet that opens passively due to pressure difference and an active inlet that opens actively due to an external signal.

[0009] Furthermore, the passive inlet is equipped with a rupture disc.

[0010] Furthermore, the active inlet is equipped with an isolation valve.

[0011] Furthermore, the outlet end of the shared flow channel is provided with a medium dispersion structure to increase the contact area between the gaseous medium and the internal liquid of the pressure suppression container.

[0012] Furthermore, the medium dispersion structure is a bubbling device.

[0013] Furthermore, the pressurized water reactor suppression and recirculation integrated system also includes a recirculation pipeline connected to the safety injection system. The recirculation pipeline is connected to the pressure suppression vessel to extract coolant as the water source for recirculation.

[0014] The present invention also provides a method for using the pressurized water reactor suppression and recirculation integrated system as described in any of the above claims, comprising the following steps: Initial pressure suppression steps: When a mass-energy release accident occurs inside the containment, the high-temperature and high-pressure gaseous medium inside the containment is introduced into the pressure suppression container through the shared flow channel. The medium exchange heat with the coolant in the pressure suppression container through the medium dispersion structure, thereby achieving pressure suppression of the containment. Depending on the pressure of the accident conditions, the gaseous medium is selectively introduced through either the passive inlet of the shared flow channel or the active inlet of the shared flow channel. Post-accident pressure suppression and recirculation steps: In the later stages of the accident, the liquid medium inside the containment vessel flows back to the pressure suppression vessel through the shared flow channel, while the safety injection system draws coolant from the pressure suppression vessel through the recirculation pipeline to establish recirculation cooling.

[0015] Furthermore, in the initial pressure suppression step of the accident: When the pressure difference between the inside and outside of the containment reaches the first pressure threshold, the active inlet is opened; When the pressure difference between the inside and outside of the containment reaches a second pressure threshold that is higher than the first pressure threshold, the passive inlet automatically opens.

[0016] By implementing this invention, the following beneficial effects are achieved: The pressurized water reactor suppression and recirculation system of the present invention integrates the containment suppression function with the recirculation recirculation safety injection / containment spraying function after a reactor mass release accident through the design of a shared flow channel. This significantly reduces the space occupied by the equipment, improves the compactness and integration of the system, and reduces the system cost.

[0017] The pressurized water reactor (PWR) suppression and recirculation system of this invention achieves different safety functions at different accident stages. Immediately after an accident, high-temperature, high-pressure steam is introduced into the suppression pool for condensation via a shared flow channel, enabling rapid and proactive control of containment pressure and temperature, effectively preventing containment damage due to overpressure. Furthermore, the system smoothly and seamlessly transitions from suppressing pressure to discharging coolant and establishing recirculation cooling, ensuring continuous and reliable cooling of the reactor core throughout the accident process and reducing the risk of severe accidents involving core meltdown due to cooling interruption. Moreover, the combination of active and passive mechanisms significantly improves the system's adaptability and success rate in handling different operating conditions, reducing reliance on active equipment such as power supplies and pumps. Even in extreme conditions such as a complete power outage, the core safety functions can still be executed automatically, significantly enhancing the system's inherent safety. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the structure of an integrated pressurized water reactor suppression and recirculation system according to an embodiment of the present invention. Detailed Implementation

[0019] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] See Figure 1 One embodiment of the present invention discloses an integrated pressurized water reactor (PWR) suppression and recirculation system, which is particularly suitable for small PWRs where space is limited. The integrated PWR system includes a pressure suppression vessel 1 and a shared flow channel 2 formed by at least one fluid channel, the shared flow channel 2 being connected to the internal spaces of both the pressure suppression vessel 1 and the containment vessel 7.

[0021] The shared flow channel 2 is configured to: in the initial stage of an accident, direct the gaseous medium inside the containment 7 to the pressure suppression container 1 to achieve pressure suppression; and in the later stage of an accident, direct the liquid medium inside the containment 7 to the pressure suppression container 1 as a water source for coolant recirculation. The gaseous medium is generally high-temperature, high-pressure steam, and the liquid medium is generally safety injection water injected by the safety injection system and spray cooling water from the spray system.

[0022] Optionally, the pressure suppression vessel 1 can be a pressure suppression pool as in the prior art, which stores initial cooling water to ensure it is kept at a certain temperature for receiving the high-temperature and high-pressure mass energy release from the internal space of the containment 7, i.e., the gas space. Generally, in a small pressurized water reactor, the reactor main equipment 8 is located at the inner bottom of the containment 7, and the pressure suppression pool is isolated and located around the reactor main equipment 8.

[0023] The shared flow channel 2 serves as a connection between the gas space of containment 7 and the pressure suppression pool, and is used for mass energy release. In this embodiment, one fluid channel forms one shared flow channel 2. To achieve efficient pressure suppression, the internal spaces of the pressure suppression vessel 1 and containment 7 can be equipped with two shared flow channels 2, respectively located on opposite sides of the reactor main equipment 8. Figure 1 Only the structure of the shared flow channel 2 on the left is illustrated with a number; the shared flow channel 2 on the right is the same as the one on the left and is not shown again. The number of fluid channels and the number of shared flow channels 2 can be set according to actual needs, and this invention does not impose any restrictions.

[0024] When a mass energy release occurs within containment 7, such as a breach in the reactor main equipment 8, high-temperature, high-pressure steam will quickly fill containment 7. This high-temperature, high-pressure steam will then enter the pressure suppression pool through the shared flow channel 2 for condensation, reducing the temperature and pressure inside the containment. The temperature of the pressure suppression pool can be controlled by the cooling subsystem within the pressure suppression system of containment 7.

[0025] This pressurized water reactor (PWR) suppression and recirculation system integrates suppression and recirculation functions into a shared flow channel 2, achieving a high degree of system integration and compact layout. It effectively solves the problems of large equipment footprint and system complexity in traditional separate designs, significantly improving the safety and economy of nuclear power plants. It overcomes the limitations of existing PWR recirculation systems under complex accident conditions, which rely on redundant design and suffer from either single-function or complex equipment.

[0026] Furthermore, in some embodiments, the shared flow channel 2 includes at least two pressure-suppressing inlets with different triggering conditions for responding to different accident conditions. The pressure-suppressing inlets are located at the bottom position 71 of the containment 7, at a height suitable for recovering the liquid phase medium.

[0027] Furthermore, in some embodiments, at least two pressure suppression inlets include a passive inlet 3 that is passively opened by pressure difference and an active inlet 4 that is actively opened by external signal.

[0028] Existing pressurized water reactor recirculation systems are typically designed passively or use active systems as backups. However, under complex accident conditions, these systems may suffer from limitations in functionality or redundancy. This invention addresses this by incorporating two independent recirculation ports—an active inlet 4 and a passive inlet 3—at the inlet of the shared flow channel 2. This combination of active and passive systems ensures reliable operation under both high-mass-energy release accidents (rapid opening of the passive recirculation port) and low-mass-energy release accidents (active recirculation port on standby), thereby improving system redundancy and flexibility.

[0029] Furthermore, in some embodiments, the passive inlet 3 is provided with a rupture disc 31, which seals the top of the passive inlet 3. During normal operation and when the internal and external pressure difference is small under accident conditions, the rupture disc 31 will not open. The rupture disc 31 automatically ruptures when the internal and external pressure difference of the containment 7 reaches a preset second pressure threshold, thus achieving passive opening.

[0030] Furthermore, in some embodiments, the active inlet 4 is equipped with an isolation valve 41, which opens upon receiving an external control signal or when the pressure difference between the inside and outside of the containment 7 reaches a first pressure threshold. During normal operation, the isolation valve 41 is closed, isolating the pressure-suppressing pool from the gas space of the containment 7 to prevent spillage or unnecessary evaporation of the medium within the pool. Upon receiving an external signal, such as remote operation by an operator in the control room, or an electrical signal issued by the automatic control system when it detects that the pressure in the containment 7 has reached the first pressure threshold, the drive device of the isolation valve 41, such as an electric or pneumatic actuator, will actively open the valve.

[0031] Furthermore, in some embodiments, a media dispersion structure 5 is provided at the outlet end of the shared flow channel 2 to increase the contact area between the gaseous medium and the internal liquid of the pressure suppression container 1. For example, the media dispersion structure 5 is a bubbling device. The surface of the bubbling device has fine pores to increase the condensation area. By optimizing the opening size and number of the pores in the bubbling device, the requirements of both the pressure suppression function and the recirculation return function can be met simultaneously, ensuring that the return flow meets the requirements, while retaining some recirculation blockage debris, thus improving system safety. The bubbling device also serves as the outlet after the cooling water return. The position of the bubbling device in terms of spatial height must be lower than the pressure suppression inlet to ensure that the liquid medium flows to the pressure suppression container 1 by gravity.

[0032] Existing pressurized water reactor recirculation systems typically lack dedicated bubbling devices, resulting in limited recirculation flow and debris retention capabilities. This invention addresses this by incorporating a bubbling device at the outlet end of the shared flow channel 2. This satisfies both pressure suppression and recirculation requirements, ensuring adequate recirculation flow while retaining some recirculation debris to prevent it from entering the pressure suppression tank and clogging the spray nozzles of the spray system. This further enhances the system's safety and reliability.

[0033] Furthermore, in some embodiments, the pressurized water reactor suppression and recirculation integrated system also includes a recirculation line 6 connected to the safety injection system. The recirculation line 6 is connected to the pressure suppression vessel 1 to extract coolant as the water source for recirculation. The recirculation line 6 may include conventional components such as return pipes and filters, which will not be described in detail here.

[0034] The present invention also provides a method of using the above-mentioned pressurized water reactor depressurization and recirculation system, comprising the following steps: Initial pressure suppression steps: When a mass-energy release accident occurs inside containment 7, the high-temperature and high-pressure gaseous medium inside containment 7 is introduced into pressure suppression container 1 through shared flow channel 2, and heat exchange is carried out with the coolant in pressure suppression container 1 through medium dispersion structure 5 to achieve pressure suppression of containment 7.

[0035] Depending on the pressure of the accident, the gaseous medium is selectively introduced through the passive inlet 3 of the shared flow channel 2 or the active inlet 4 of the shared flow channel 2.

[0036] Post-accident pressure suppression and recirculation steps: In the later stages of the accident, the liquid medium inside containment 7 flows back to pressure suppression vessel 1 through shared flow channel 2. At the same time, the safety injection system draws coolant from pressure suppression vessel 1 through recirculation line 6 to establish recirculation cooling.

[0037] Furthermore, in the initial pressure suppression steps of an accident: When the pressure difference between the inside and outside of containment 7 reaches a first pressure threshold, the active inlet 4 is opened. Here, the pressure difference between the inside and outside of containment 7 refers primarily to the difference between the pressure inside the containment 7 and the pressure within the shared flow channel 2. When the pressure difference between the inside and outside of containment 7 reaches a second pressure threshold higher than the first pressure threshold, the passive inlet 3 is automatically opened. Here, the first pressure threshold is less than the second pressure threshold.

[0038] The working principle of this invention is as follows: In the initial stages of the accident, after a breach occurs in the reactor compartment, high-temperature, high-pressure steam is released into the gas space inside containment 7. The pressure inside containment 7 rises, and when it reaches the first pressure threshold, the isolation valve 41 of the active inlet 4 opens, allowing the high-temperature, high-pressure steam to enter the pressure suppression vessel 1 through the shared flow channel 2. If the pressure continues to rise and reaches the second pressure threshold, the rupture disc 31 of the passive inlet 3 automatically ruptures, providing an additional pressure relief channel. The steam condenses in the coolant of the pressure suppression vessel 1 as bubbles through a bubbling device, achieving rapid pressure suppression.

[0039] In the later stages of the accident, the safety injection system injects cryogenic water into the primary loop, while the containment 7 spray system activates to spray water into the containment 7 gas space. This water flows to the bottom of containment 7 and then returns to pressure suppression container 1 through shared channel 2. When the water supply in the safety injection tank is insufficient, the safety injection system switches to drawing water from pressure suppression container 1 to establish long-term recirculation cooling.

[0040] By implementing this invention, the following beneficial effects are achieved: The pressurized water reactor suppression and recirculation system of the present invention integrates the containment 7 suppression function with the recirculation recirculation safety injection / containment 7 spraying function after a reactor mass release accident through the design of the shared flow channel 2. This significantly reduces the space occupied by the equipment, improves the compactness and integration of the system, and reduces the system cost.

[0041] The pressurized water reactor (PWR) suppression and recirculation system of this invention achieves different safety functions at different accident stages. Immediately after an accident, high-temperature, high-pressure steam is introduced into the suppression pool for condensation via the shared flow channel 2, enabling rapid and proactive control of the pressure and temperature of the containment vessel 7, effectively preventing damage to the containment vessel 7 due to overpressure. Furthermore, the system smoothly and seamlessly transitions between suppressing pressure, discharging coolant, and establishing recirculation cooling, ensuring continuous and reliable cooling of the reactor core throughout the entire accident process, reducing the risk of severe accidents caused by core meltdown due to cooling interruption. Moreover, the combination of active and passive mechanisms greatly improves the system's adaptability and success rate in handling different operating conditions, reducing reliance on active equipment such as power supplies and pumps. Even in extreme conditions such as a complete power outage, the core safety functions can still be automatically executed, significantly enhancing the system's inherent safety.

[0042] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those skilled in the art, the above embodiments or technical features can be freely combined, and several modifications and improvements can be made without departing from the concept of the present invention. These all fall within the protection scope of the present invention. That is, the embodiments described "in some embodiments" can be freely combined with any of the embodiments above and below. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. An integrated system for pressurized water reactor suppression and recirculation, characterized in that, It includes a pressure suppression container (1) and a shared flow channel (2) formed by at least one fluid channel, wherein the shared flow channel (2) is connected to the internal space of the pressure suppression container (1) and the containment vessel (7); The shared flow channel (2) is configured to: in the early stage of an accident, guide the gaseous medium in the internal space of the containment vessel (7) to the pressure suppression container (1) to achieve pressure suppression; and in the later stage of an accident, guide the liquid medium in the internal space of the containment vessel (7) to the pressure suppression container (1) as a water source for coolant recirculation.

2. The pressurized water reactor suppression and recirculation integrated system according to claim 1, characterized in that, The shared flow channel (2) includes at least two suppression inlets with different triggering conditions for responding to different accident conditions.

3. The pressurized water reactor suppression and recirculation integrated system according to claim 2, characterized in that, At least two of the pressure suppression inlets include a passive inlet (3) that is passively opened by pressure difference and an active inlet (4) that is actively opened by external signal.

4. The pressurized water reactor suppression and recirculation integrated system according to claim 3, characterized in that, The passive inlet (3) is equipped with a rupture disc (31).

5. The pressurized water reactor suppression and recirculation integrated system according to claim 3, characterized in that, The active inlet (4) is equipped with an isolation valve (41).

6. The pressurized water reactor depressurization and recirculation integrated system according to any one of claims 1-5, characterized in that, The outlet end of the shared flow channel (2) is provided with a medium dispersion structure (5) to increase the contact area between the gaseous medium and the internal liquid of the pressure suppression container (1).

7. The pressurized water reactor suppression and recirculation integrated system according to claim 6, characterized in that, The medium dispersion structure (5) is a bubbling device.

8. The pressurized water reactor depressurization and recirculation integrated system according to any one of claims 1-5, characterized in that, The pressurized water reactor suppression and recirculation integrated system also includes a recirculation pipeline (6) connected to the safety injection system. The recirculation pipeline (6) is connected to the pressure suppression vessel (1) to extract coolant as the water source for recirculation.

9. A method of using the integrated pressurized water reactor suppression and recirculation system according to any one of claims 1-8, characterized in that, Includes the following steps: Initial pressure suppression steps: When a mass-energy release accident occurs inside the containment (7), the high-temperature and high-pressure gaseous medium inside the containment (7) is introduced into the pressure suppression container (1) through the shared flow channel (2), and heat exchange is carried out with the coolant inside the pressure suppression container (1) through the medium dispersion structure (5) to achieve pressure suppression of the containment (7); Depending on the pressure of the accident, the gaseous medium is selectively introduced through the passive inlet (3) of the shared flow channel (2) or the active inlet (4) of the shared flow channel (2); Post-accident pressure suppression and recirculation steps: In the later stages of the accident, the liquid medium in the containment vessel (7) is returned to the pressure suppression container (1) through the shared flow channel (2), and at the same time, the safety injection system draws coolant from the pressure suppression container (1) through the recirculation line (6) to establish recirculation cooling.

10. The method of using the integrated pressurized water reactor suppression and recirculation system according to claim 9, characterized in that, In the initial pressure suppression steps of the accident: When the pressure difference between the inside and outside of the containment vessel (7) reaches the first pressure threshold, the active inlet (4) is opened; When the pressure difference between the inside and outside of the containment (7) reaches a second pressure threshold that is higher than the first pressure threshold, the passive inlet (3) automatically opens.

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