A nuclear power plant molten material in-vessel retention system

Abstract

A nuclear power plant molten core retention system. The system comprises an ex-vessel water injection system for ex-vessel water injection to a reactor (10) in a severe accident phase of the reactor (10), and an in-vessel water injection system for in-vessel water injection to the reactor (10) in the severe accident phase of the reactor (10), the in-vessel water injection system using boron-containing water. The molten core retention is achieved by using both in-vessel and ex-vessel water injection, which greatly improves the safety margin of the nuclear power plant reactor (10).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear power plants, more particularly to a nuclear power plant molten core retention system. BACKGROUND

[0002] Being able to cope with and mitigate the core melt accident is a typical feature of the third generation reactor, and the third generation reactor "Hualong No. 1" independently developed by China adopts a molten core retention strategy to cope with the core melt accident. At present, Hualong No. 1 uses a pit water injection system to achieve molten core retention, and the water injected into the pit cools the lower head wall to prevent the lower head from being melted through. However, the core melt is a late phenomenon of severe accidents, and there are many uncertainties. The existing software and analysis capability is difficult to accurately calculate the heat transfer of the lower head pool. In addition, the safety margin of the molten core retention system is small, and the software analysis uncertainty has a great impact on the effectiveness evaluation of the molten core retention strategy, affecting the safety of the reactor. Therefore, it is necessary to improve the existing molten core retention system to improve the safety margin of the reactor. SUMMARY

[0004] TECHNICAL PROBLEM

[0005] The technical problem to be solved by the present application is to provide a nuclear power plant molten core retention system to solve the above-mentioned defects of the prior art.

[0006] SOLUTION TO THE PROBLEM

[0007] TECHNICAL SOLUTION

[0008] The technical scheme adopted by the present application to solve the technical problem is: a nuclear power plant molten core retention system is constructed, which comprises an external water injection system and an internal water injection system, the external water injection system is used to inject water into the pit of the reactor during the severe accident phase of the reactor, and the internal water injection system is used to inject water into the pressure vessel of the reactor during the severe accident phase of the reactor. The water used by the internal water injection system is boron-containing water.

[0009] Further, in the nuclear power plant molten core retention system described in the present application, the internal water injection system comprises a high-pressure water tank for storing inert gas and boron-containing water, the water outlet of the high-pressure water tank is connected to the first end of the first check valve V9 through a pipeline, and the second end of the first check valve V9 is connected to the internal of the reactor through a pipeline.

[0010] The pressure of the inert gas in the high-pressure water tank is greater than the standard atmospheric pressure, when the internal pressure of the reactor is less than the pressure of the first end of the first check valve V9, the high-pressure water tank starts to inject boron-containing water into the internal of the reactor, and after the injection of boron-containing water is completed, the inert gas in the high-pressure water tank is injected.

[0011] Further, in the nuclear power plant corium in-vessel retention system, an electric valve V8 is arranged on the pipeline between the outlet of the high-pressure water tank and the first check valve V9.

[0012] The electric valve V8 is in an open state, and the electric valve V8 is closed during reactor maintenance.

[0013] Further, in the nuclear power plant corium in-vessel retention system, the pressure of the inert gas in the high-pressure water tank ranges from 0.1 MPa to 2 MPa.

[0014] Further, in the nuclear power plant corium in-vessel retention system, the inner diameters of the pipeline between the outlet of the high-pressure water tank and the first end of the first check valve V9 and the pipeline between the second end of the first check valve V9 and the reactor in-vessel range from 50 mm to 80 mm.

[0015] Further, in the nuclear power plant corium in-vessel retention system, the lowest point of the high-pressure water tank is higher than the highest point of the reactor.

[0016] Further, the nuclear power plant corium in-vessel retention system further comprises a refueling water tank connected to the inlet pipeline of the high-pressure water tank, and the refueling water tank stores boron-containing water.

[0017] An electric pump P1 and an electric valve V11 are arranged on the pipeline between the inlet of the high-pressure water tank and the refueling water tank, and the refueling water tank is used to supplement the boron-containing water in the high-pressure water tank.

[0018] Further, in the nuclear power plant corium in-vessel retention system, the ex-vessel water injection system comprises a high-position normal-pressure water tank, an electric valve V4, and a second check valve V6, and the lowest point of the high-position normal-pressure water tank is higher than the highest point of the reactor.

[0019] The bottom outlet of the high-position normal-pressure water tank is connected to the first end of the electric valve V4 through a pipeline, the second end of the electric valve V4 is connected to the first end of the second check valve V6 through a pipeline, and the second end of the second check valve V6 is connected to the ex-vessel of the reactor through a pipeline.

[0020] The electric valve V4 is in a closed state during normal operation of the reactor, and is opened when the outlet temperature of the reactor core exceeds 650 ℃, and after being opened, the water in the high-position normal-pressure water tank is injected into the ex-vessel of the reactor.

[0021] Further, the nuclear power plant corium in-vessel retention system further comprises a standby electric valve V5, the first end of the standby electric valve V5 is connected to the first end of the electric valve V4 through a pipeline, and the second end of the standby electric valve V5 is connected to the second end of the electric valve V4 through a pipeline.

[0022] The standby electric valve V5 is closed during normal operation of the reactor, and the electric valve V4 is opened first when the outlet temperature of the reactor core exceeds 650 DEG C, and the standby electric valve V5 is opened when the electric valve V4 fails to open.

[0023] Further, the nuclear power plant molten core retention system further comprises a stop valve V7 arranged on the pipeline between the second end of the second check valve V6 and the outside of the reactor core, and the stop valve V7 is used to terminate water injection when water injection is mistakenly performed.

[0024] Further, in the nuclear power plant molten core retention system, the high-level normal-pressure water tank comprises at least two bottom water outlets, each of which is connected to the first end of the electric valve V4 through a pipeline, and an electric valve is arranged on the pipeline corresponding to each bottom water outlet, and all the electric valves are closed during normal operation of the reactor, and are opened when the outlet temperature of the reactor core exceeds 650 DEG C.

[0025] Further, in the nuclear power plant molten core retention system, the pipe opening of the pipeline corresponding to each bottom water outlet extends to the inside of the high-level normal-pressure water tank, the pipe opening of the pipeline corresponding to each bottom water outlet has different extension heights, and the water amount above the pipe opening of the pipeline with the highest extension height is equal to the free volume of the pit of the reactor.

[0026] Further, in the nuclear power plant molten core retention system, the high-level normal-pressure water tank comprises three bottom water outlets, an electric valve V1 is arranged on the pipeline between the first bottom water outlet and the first end of the electric valve V4, an electric valve V2 is arranged on the pipeline between the second bottom water outlet and the first end of the electric valve V4, and an electric valve V3 is arranged on the pipeline between the third bottom water outlet and the first end of the electric valve V4, and the electric valve V1, the electric valve V2 and the electric valve V3 are closed during normal operation of the reactor, and are opened when the outlet temperature of the reactor core exceeds 650 DEG C.

[0027] The pipeline corresponding to the first bottom water outlet does not extend in the high-level normal-pressure water tank, the extension height of the pipeline corresponding to the third bottom water outlet in the high-level normal-pressure water tank is higher than the extension height of the pipeline corresponding to the second bottom water outlet in the high-level normal-pressure water tank, and the water amount above the pipe opening of the pipeline corresponding to the third bottom water outlet is equal to the free volume of the pit of the reactor.

[0028] Further, the nuclear power plant molten core retention system provided by the present application further comprises a refueling water tank connected to the water inlet pipe of the high-level normal-pressure water tank, and an electric pump P1 and an electric valve V10 are arranged on the pipe between the water inlet of the high-level normal-pressure water tank and the refueling water tank, and the refueling water tank is used to supplement water into the high-level normal-pressure water tank.

[0029] Further, in the nuclear power plant molten core retention system provided by the present application, the water in the high-level normal-pressure water tank is boron-containing water.

[0030] The water in the refueling water tank is boron-containing water.

[0031] Further, in the nuclear power plant molten core retention system provided by the present application, all the electric valves in the system are powered by uninterrupted power supply.

[0032] Advantages of the present application

[0033] Advantages of the present application

[0034] The nuclear power plant molten core retention system provided by the present application has the following advantages: the present application realizes molten core retention by simultaneously injecting water into the reactor and outside the reactor, and greatly improves the safety margin of the nuclear power plant reactor.

[0035] Brief Description of the Drawings BRIEF DESCRIPTION OF DRAWINGS

[0036] The present application will be further described below in conjunction with the drawings and embodiments, wherein:

[0037] Figure 1 Fig. 1 is a structural schematic view of a nuclear power plant molten core retention system provided by an embodiment.

[0038] Best Mode for Carrying Out the Invention

[0039] Best Mode for Carrying Out the Invention

[0040] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail below with reference to the drawings.

[0041] Embodiments of the Invention Embodiments

[0042] Reference Figure 1The nuclear power plant molten core retention system of the embodiment includes an ex-vessel water injection system and an in-vessel water injection system. The ex-vessel water injection system is used to inject water into the reactor 10 in a severe accident phase of the reactor 10, which means to inject water into the reactor and to immerse the pressure vessel in water. The in-vessel water injection system is used to inject water into the reactor 10 in a severe accident phase of the reactor 10, which means to inject water into the pressure vessel of the reactor. The water used by the in-vessel water injection system is boron-containing water. The abnormality of the reactor 10 means that the detection system detects a severe accident signal, and the water injection is started after the detection of the severe accident signal.

[0043] The in-vessel water injection system of the nuclear power plant molten core retention system of the embodiment includes a high-pressure water tank 20 for storing inert gas and boron-containing water. The outlet of the high-pressure water tank 20 is connected to the first end of a first check valve V9 through a pipeline, and the second end of the first check valve V9 is connected to the in-vessel of the reactor 10 through a pipeline. The system is an automatic operation system. The pressure of the inert gas in the high-pressure water tank 20 is greater than the standard atmospheric pressure. When the reactor system is normally operated, the pressure in the pressure vessel is greater than the pressure in the pressurized water tank. Because the first check valve V9 exists, the coolant in the pressure vessel will not flow back to the pressurized water tank. In a severe accident condition, the primary loop of the reactor is depressurized, which causes the pressure in the in-vessel of the reactor 10 to gradually decrease. When the pressure in the in-vessel of the reactor 10 is less than the pressure at the first end of the first check valve V9, the high-pressure water tank 20 starts to inject boron-containing water into the in-vessel of the reactor 10, and then injects the inert gas in the high-pressure water tank 20. Because water injection into the in-vessel will produce hydrogen, in order to prevent a secondary accident, the embodiment uses inert gas mixed with hydrogen to avoid explosion and improve safety. Alternatively, the inert gas can be low-cost nitrogen, and other inert gases can also be selected.

[0044] Alternatively, in the nuclear power plant molten core retention system of the embodiment, an electric valve V8 is arranged on the pipeline between the outlet of the high-pressure water tank 20 and the first check valve V9. The electric valve V8 is in a normally open state. The electric valve V8 is closed when the reactor 10 is repaired to prevent the system from being automatically put into operation.

[0045] Alternatively, in the nuclear power plant molten core retention system of the embodiment, the pressure of the inert gas in the high-pressure water tank 20 ranges from 0.1 MPa to 2 MPa.

[0046] Alternatively, in the nuclear power plant molten corium in-vessel retention system of the embodiment, the inner diameter of the pipe between the outlet of the high-pressure water tank 20 and the first end of the first check valve V9 and the pipe between the second end of the first check valve V9 and the in-vessel of the reactor 10 ranges from 50 mm to 80 mm. In the embodiment, since the existing IVR water tank is used for simultaneous water injection into the pit and the in-vessel, the water volume of the IVR water tank is limited, and the pipe with a diameter greater than 80 mm is used for water injection, which can only sustain a short time of water injection. Therefore, after the water injection is stopped, the core melting process restarts, and the size of the molten pool quickly rises to the level without water injection. The pipe with a diameter less than 50 mm is used for water injection, which can provide a longer time of continuous cooling, but the cooling effect is not obvious due to the small injection flow, and the effect on reducing the size of the molten pool is also small. Therefore, from the effect of the in-vessel water injection on the molten pool, the water injection with a diameter of 50 mm to 80 mm is the optimal choice. Under this diameter, the water injection delayed for 0-50 minutes has the most obvious effect on reducing the size of the molten pool.

[0047] Alternatively, in the nuclear power plant molten corium in-vessel retention system of the embodiment, the lowest point of the high-pressure water tank 20 is higher than the highest point of the reactor 10.

[0048] Alternatively, the nuclear power plant molten corium in-vessel retention system of the embodiment further comprises a refueling water tank 30 connected to the inlet pipe of the high-pressure water tank 20, and the refueling water tank 30 stores boron-containing water; an electric pump P1 and an electric valve V11 are arranged on the pipe between the inlet of the high-pressure water tank 20 and the refueling water tank 30, and the refueling water tank 30 is used to supplement the boron-containing water in the high-pressure water tank 20. The nuclear power plant molten corium in-vessel retention system of the embodiment only needs a battery-driven electric valve, and the entire water injection process is passive and can continue to operate under the condition of full plant power failure. The electric valve V11 is in a normally closed state, and the electric pump P1 and the electric valve V11 are opened to inject water into the high-pressure water tank 20 after 12 hours of the occurrence of a severe accident (according to the operation regulations of the nuclear power plant, the mobile power supply is in place 6 hours after the accident occurs). The air inlet of the high-pressure water tank 20 is connected to an inert gas storage tank (not shown in the figure), and the inert gas storage tank is used to inject inert gas into the high-pressure water tank 20.

[0049] In the nuclear power plant molten corium in-vessel retention system of the embodiment, the ex-vessel water injection system comprises a high-level atmospheric water tank 40, an electric valve V4 and a second check valve V6, the lowest point of the high-level atmospheric water tank 40 is higher than the highest point of the reactor 10, and thus the water in the high-level atmospheric water tank 40 can enter the pit without power supply, thereby avoiding the situation that the reactor cannot be injected with water due to the lack of power supply after an accident occurs. Alternatively, the water in the high-level atmospheric water tank 40 of the nuclear power plant molten corium in-vessel retention system of the embodiment is boron-containing water. The bottom water outlet of the high-level atmospheric water tank 40 is connected to the first end of the electric valve V4 through a pipeline, the second end of the electric valve V4 is connected to the first end of the second check valve V6 through a pipeline, and the second end of the second check valve V6 is connected to the outside of the reactor 10 through a pipeline. The electric valve V4 is in a closed state when the reactor 10 is in normal operation, and is opened when the outlet temperature of the reactor 10 exceeds 650°C. After the electric valve V4 is opened, the water in the high-level atmospheric water tank 40 is injected into the outside of the reactor 10.

[0050] Alternatively, the nuclear power plant molten corium in-vessel retention system of the embodiment further comprises a standby electric valve V5, the first end of the standby electric valve V5 is connected to the first end of the electric valve V4 through a pipeline, and the second end of the standby electric valve V5 is connected to the second end of the electric valve V4 through a pipeline. The standby electric valve V5 is in a closed state when the reactor 10 is in normal operation, and is opened after the electric valve V4 is opened when the outlet temperature of the reactor 10 exceeds 650°C. If the electric valve V4 fails to be opened, the standby electric valve V5 is opened, and the water in the high-level atmospheric water tank 40 is injected into the outside of the reactor 10.

[0051] Alternatively, the nuclear power plant molten corium in-vessel retention system of the embodiment further comprises a stop valve V7 arranged on the pipeline between the second end of the second check valve V6 and the outside of the reactor 10, and the stop valve V7 is used to terminate water injection when mis-injection occurs.

[0052] Alternatively, the high-level atmospheric water tank 40 of the nuclear power plant molten corium in-vessel retention system of the embodiment comprises at least two bottom water outlets, each bottom water outlet is connected to the first end of the electric valve V4 through a pipeline, and an electric valve is arranged on the pipeline of each bottom water outlet. All the electric valves are in a closed state when the reactor 10 is in normal operation, and are opened when the outlet temperature of the reactor 10 exceeds 650°C.

[0053] As an option, after detecting the severe accident signal, the high-level normal-pressure water tank 40 needs to be started, and the reactor pit is quickly filled with water within 20-120 minutes, at which time the water injection flow rate is required to be large. After the reactor pit is filled with water, the water in the reactor pit will decrease due to evaporation, at which time the water in the reactor pit needs to be continuously injected to maintain the liquid level required for natural circulation. Because the water tank has a limited volume, in order to improve the severe accident mitigation capability of the system, the water injection flow rate needs to be matched with the evaporation amount. Therefore, in the molten material in-vessel retention system of the nuclear power plant in this embodiment, the pipe opening of each bottom water outlet corresponding pipe extends into the interior of the high-level normal-pressure water tank 40, the pipe openings of the pipes of each bottom water outlet corresponding pipe have different extension heights, that is, the pipe openings of the pipes of multiple bottom water outlet corresponding pipes are distributed at different heights, the pipe openings of the pipes of different bottom water outlet corresponding pipes are distributed at different heights, and the water amount above the pipe opening of the pipe with the highest extension height is equal to the free volume of the reactor pit of the reactor 10. At the beginning of water injection, all the bottom water outlets simultaneously inject water, and the reactor pit is quickly filled with water within 20-120 minutes; after the reactor pit is filled with water, the water level of the high-level normal-pressure water tank 40 decreases below the pipe opening of the pipe with the highest extension height, and then the water injection amount is correspondingly reduced. In this way, as the water level in the high-level normal-pressure water tank 40 decreases, the pipe openings that can inject water are fewer and fewer, and the water injection amount is gradually smaller, so as to adapt to the decrease of the evaporation amount and maintain the balance of the water in the reactor pit.

[0054] For example, the high-level normal-pressure water tank 40 includes three bottom water outlets, the pipe between the first bottom water outlet and the first end of the electric valve V4 is provided with the electric valve V1, the pipe between the second bottom water outlet and the first end of the electric valve V4 is provided with the electric valve V2, and the pipe between the third bottom water outlet and the first end of the electric valve V4 is provided with the electric valve V3. The electric valves V1, V2 and V3 are in a closed state during normal operation of the reactor 10, and are opened after the outlet temperature of the reactor core of the reactor 10 exceeds 650°C. The corresponding pipe of the first bottom water outlet has no extension in the high-level normal-pressure water tank 40, the corresponding pipe of the third bottom water outlet has a higher extension height in the high-level normal-pressure water tank 40 than the corresponding pipe of the second bottom water outlet, and the water amount above the pipe opening of the corresponding pipe of the third bottom water outlet is equal to the free volume of the reactor pit of the reactor 10. At the beginning of water injection, the first bottom water outlet, the second bottom water outlet and the third bottom water outlet simultaneously inject water quickly, and the reactor pit is flooded in a short time. After the reactor pit is filled with water, the pipe opening of the corresponding pipe of the third bottom water outlet is exposed, and only the first bottom water outlet and the second bottom water outlet can inject water simultaneously, so that the water injection speed is relatively reduced; after a period of time, the water evaporation amount is further reduced, and only the first bottom water outlet can inject water, so that the water injection speed is further reduced.

[0055] Alternatively, the nuclear power plant molten corium in-vessel retention system of the embodiment further comprises a refueling water tank 30 connected to the water inlet pipe of the high-level atmospheric water tank 40, and an electric pump P1 and an electric valve V10 are arranged on the pipe between the water inlet of the high-level atmospheric water tank 40 and the refueling water tank 30, and the refueling water tank 30 is used to supplement water into the high-level atmospheric water tank 40. Alternatively, the water in the refueling water tank 30 is boron-containing water. The electric valve V10 is in a normally closed state, and the electric pump P1 and the electric valve V10 are opened to inject water into the high-level atmospheric water tank 40 after a period of time, for example, 12 hours, after the severe accident occurs.

[0056] Alternatively, all the electric valves in the nuclear power plant molten corium in-vessel retention system of the embodiment are powered by an uninterruptible power supply, that is, the electric valve V1, the electric valve V2, the electric valve V3, the electric valve V4, the electric valve V5, the electric valve V8, the electric valve V10, and the electric valve V11 are powered by an uninterruptible power supply.

[0057] After the in-vessel and out-of-vessel water injection of the embodiment, the time when the lower head molten pool of the reactor pressure vessel (RPV) of the nuclear power plant reaches the maximum decay heat is delayed by about 8 hours compared with the condition without in-vessel water injection, and the decay heat is also reduced by nearly 30%. The heat flux density of the condition with in-vessel water injection is greatly reduced compared with the condition without in-vessel water injection, and the peak value is reduced by more than 30%, greatly increasing the safety margin of IVR. The calculation results show that after the in-vessel water injection is completed, even if the core melting process restarts, the total amount of in-vessel molten material does not decrease because of the in-vessel water injection, but because the time process is greatly delayed, the decay heat is also greatly reduced, so the heat flux density of the molten pool heat transfer is reduced, and the safety margin is increased from 10% to about 50%. The embodiment can significantly improve the safety performance of the reactor.

[0058] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0059] Those skilled in the art will further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in, for example, electronic hardware, computer software, or combinations of both. To clearly illustrate the interchangeability of hardware and software, the elements of each example have been described in general terms in the above description. Whether such functionality is implemented in hardware or software depends on the particular application and design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in varying ways for each particular application, but such implementation should not be interpreted as a departure from the scope of the present application.

[0060] The steps of a method or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in random access memory (RAM), flash memory, read-only memory (ROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0061] The above embodiments are only to illustrate the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it accordingly, and cannot limit the protection scope of the present application. Any equivalent changes and modifications made within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A nuclear power plant molten material in-vessel retention system, characterized by, The system comprises an out-of-pile water injection system for out-of-pile water injection to the reactor (10) in a severe accident stage of the reactor (10) and an in-pile water injection system for in-pile water injection to the reactor (10) in the severe accident stage of the reactor (10), wherein the in-pile water injection system uses boron-containing water; The in-pile water injection system comprises a high-pressure water tank (20) for storing inert gas and boron-containing water, wherein an outlet of the high-pressure water tank (20) is connected to a first end of a first check valve (V9) through a pipeline, and a second end of the first check valve (V9) is connected to an in-pile of the reactor (10) through a pipeline; The pressure of the inert gas in the high-pressure water tank (20) is greater than the standard atmospheric pressure, and when the in-pile pressure of the reactor (10) is less than the pressure of the first end of the first check valve (V9), the high-pressure water tank (20) starts to inject boron-containing water into the in-pile of the reactor (10), and after the injection of the boron-containing water is completed, the inert gas in the high-pressure water tank (20) is injected, wherein the inner diameter of the pipeline ranges from 50 mm to 80 mm; The pressure of the inert gas in the high-pressure water tank (20) ranges from 0.1 MPa to 2 MPa; The out-of-pile water injection system comprises a high-level normal-pressure water tank (40), an electric valve (V4) and a second check valve (V6), wherein the lowest point of the high-level normal-pressure water tank (40) is higher than the highest point of the reactor (10); The bottom outlet of the high-level normal-pressure water tank (40) is connected to a first end of the electric valve (V4) through a pipeline, a second end of the electric valve (V4) is connected to a first end of the second check valve (V6) through a pipeline, and a second end of the second check valve (V6) is connected to an out-of-pile of the reactor (10) through a pipeline; The electric valve (V4) is in a closed state when the reactor (10) is in normal operation, and is opened when the outlet temperature of the reactor (10) exceeds 650℃, and after being opened, the water in the high-level normal-pressure water tank (40) is injected into the out-of-pile of the reactor (10); The high-level atmospheric water tank (40) includes three bottom water outlets, an electric valve (V1) is arranged on the pipeline between the first bottom water outlet and the first end of the electric valve (V4), an electric valve (V2) is arranged on the pipeline between the second bottom water outlet and the first end of the electric valve (V4), and an electric valve (V3) is arranged on the pipeline between the third bottom water outlet and the first end of the electric valve (V4), the electric valve (V1), the electric valve (V2) and the electric valve (V3) are in a closed state during normal operation of the reactor (10) and are opened after the outlet temperature of the reactor core (10) exceeds 650 DEG C; the corresponding pipeline of the first bottom water outlet does not extend in the high-level atmospheric water tank (40), the extension height of the corresponding pipeline of the third bottom water outlet in the high-level atmospheric water tank (40) is higher than the extension height of the corresponding pipeline of the second bottom water outlet in the high-level atmospheric water tank (40), and the water amount above the pipe opening of the corresponding pipeline of the third bottom water outlet is equal to the free volume of the reactor pit (10); all the electric valves in the system are powered by an uninterruptible power supply.

2. The nuclear power plant corium in-vessel retention system of claim 1, wherein, An electric valve (V8) is arranged on the pipeline between the outlet of the high-pressure water tank (20) and the first check valve (V9); The electric valve (V8) is in a normally open state and is closed during maintenance of the reactor (10).

3. The nuclear power plant corium in-vessel retention system of claim 1, wherein, The lowest point of the high-pressure water tank (20) is higher than the highest point of the reactor (10).

4. The nuclear power plant corium in-vessel retention system of claim 1, wherein, A refueling water tank (30) connected to the water inlet pipeline of the high-pressure water tank (20) is further included, and the refueling water tank (30) stores boron-containing water; An electric pump (P1) and an electric valve (V11) are arranged on the pipeline between the water inlet of the high-pressure water tank (20) and the refueling water tank (30), and the refueling water tank (30) is used to supplement the boron-containing water in the high-pressure water tank (20).

5. The nuclear power plant corium in-vessel retention system of claim 1, wherein, A standby electric valve (V5) is further included, a first end of the standby electric valve (V5) is connected to the first end of the electric valve (V4) through a pipeline, and a second end of the standby electric valve (V5) is connected to the second end of the electric valve (V4) through a pipeline; The standby electric valve (V5) is in a closed state during normal operation of the reactor (10), the electric valve (V4) is first opened when the outlet temperature of the reactor core (10) exceeds 650 DEG C, the standby electric valve (V5) is opened when the electric valve (V4) fails to open, and the water in the high-level atmospheric water tank (40) is injected into the reactor (10).

6. The nuclear power plant corium in-vessel retention system of claim 1, wherein, A stop valve (V7) arranged on the pipeline between the second end of the second check valve (V6) and the outside of the reactor (10) is further included, and the stop valve (V7) is used to terminate water injection when water injection is mistakenly performed.

7. The nuclear power plant corium in-vessel retention system of claim 1, wherein, The high-level atmospheric water tank (40) includes at least two bottom water outlets, each bottom water outlet is connected to the first end of the electric valve (V4) through a pipeline, and an electric valve is arranged on the pipeline of each bottom water outlet, and all the electric valves are in a closed state during normal operation of the reactor (10) and are opened when the outlet temperature of the reactor core (10) exceeds 650 DEG C.

8. The nuclear power plant corium in-vessel retention system of claim 7, wherein, Each of the bottom water outlets corresponds to a pipe nozzle extending to the inside of the high-level atmospheric water tank (40), the pipe nozzles of each of the bottom water outlets have different extension heights, and the water amount above the pipe nozzle with the highest extension height is equal to the free volume of the reactor pit (10).

9. The nuclear power plant corium in-vessel retention system of claim 1, wherein, The fuel replacement water tank (30) is further connected to the water inlet pipe of the high-level atmospheric water tank (40), an electric pump (P1) and an electric valve (V10) are arranged on the pipe between the water inlet of the high-level atmospheric water tank (40) and the fuel replacement water tank (30), and the fuel replacement water tank (30) is used to supplement water into the high-level atmospheric water tank (40).

10. The nuclear power plant corium in-vessel retention system of claim 9, wherein, The water in the high-level atmospheric water tank (40) is boron-containing water. The water in the fuel replacement water tank (30) is boron-containing water.

Images