JP6731386B2 - Nuclear reactor equipment - Google Patents

Description

The present invention relates to a nuclear reactor facility having a recirculation strainer backwash mechanism.

In the reactor building at the time of the accident, various foreign substances (hereinafter referred to as debris) such as heat insulating materials, concrete pieces, and chemical components exuded from concrete are generated due to pipe breakage and the like. The generated debris flows into the recirculation pool (RWSP) installed in the lower part of the reactor building together with the cooling liquid sprayed to cool the inside. The recirculation pool is configured such that the flow velocity of the cooling liquid locally increases near the sump, and the flow of the cooling liquid into the sump is accelerated. The sump screen (filter) covers the sump inflow hole to filter the debris that has arrived there, so that the debris does not flow into the sump.

By the way, when the debris that reaches the sump screen and accumulates too much, a part of the sump inflow hole is blocked, and the pressure loss when the cooling liquid flows into the sump becomes excessive, and the effective suction head (NPSH ) Becomes a problem. As a means for solving this problem, for example, when the blockage of the sump is higher than expected, there is a means for backwashing the sump screen by backflowing the cooling liquid to once eliminate clogging due to debris. Patent Document 1 discloses a cleaning system in which a fluid supply source for supplying a pressurized fluid is newly provided in order to perform this backwashing.

JP, 2017-90187, A

However, in the cleaning system of Patent Document 1, it is necessary to lay new pipes and to provide a pump for backwashing and the like, which is considered difficult to implement due to restrictions on the arrangement conditions. Further, in the cleaning system of Patent Document 1, when the backwash is repeatedly performed, it is necessary to replenish the fluid for the backwash each time, which causes a new problem that an increase in cost cannot be avoided.

The present invention has been made in view of the above circumstances, and using an existing cooling facility, it is possible to suppress an increase in pressure loss when the cooling liquid flows into the sump due to the accumulation of debris. The purpose is to provide equipment.

In order to solve the above problems, the present invention employs the following means.

(1) A reactor facility according to one aspect of the present invention is provided in a reactor containment room for storing a reactor and a lower floor of the reactor containment room, in which first water is stored, and a floor is provided. A reactor containment vessel having a recirculation pool chamber (corresponding to a pool of a pressure suppression chamber in the case of BWR) equipped with a sump screen on its surface, and provided outside the reactor containment vessel, one end of which is the sump screen Of the circulation pipe having a first opening/closing valve connected to the recirculation pool chamber and the other end of which is connected to the reactor containment chamber, and the sump screen and the first opening/closing of the circulation pipe. A pump attached to a portion between the valves and capable of pumping the first water to the reactor containment chamber side, and second water are accommodated, and the lower end of the accommodation space is the recirculation pool chamber in the vertical direction. A tank located above the water surface of the first water, and a backwashing pipe that connects the tank and the circulation pipe and has a second on-off valve.

(2) In the nuclear reactor equipment according to (1) above, the backwash pipe branches into a pipe having the second opening/closing valve and a pipe not having the second opening/closing valve, each of which is the above-mentioned pipe. It is preferable that the connection position of the pipe connected to the circulation pipe and having the second opening/closing valve is closer to the recirculation pool chamber than the connection position of the pipe not having the second opening/closing valve.

(3) In the nuclear reactor equipment according to (1) or (2), the pump is a pipe for circulation at a position farther from the recirculation pool chamber than a connection position of a pipe having the second opening/closing valve. Is preferably connected to.

(4) In the nuclear reactor facility according to any one of (1) to (3), the pump is connected to the recirculation pool chamber from a connection position of a pipe that does not have the second on-off valve. It is preferable to be connected to the circulation pipe at a close position.

(5) In the nuclear reactor equipment according to any one of (1) to (4), the pipe having no second opening/closing valve is the second water stored in the tank. It is preferable to have a third opening/closing valve that automatically opens and closes according to the amount of

(6) In the nuclear reactor equipment according to any one of (1) to (5) above, the pipe having no second on-off valve may have water only in a direction from the circulation pipe to the tank. It is preferred to have a non-return valve mounted flush-through.

The nuclear reactor equipment of the present invention is provided with a mechanism for backwashing the sump screen when the blockage rate of the sump screen due to debris becomes too high. The backwashing of the sump screen is performed by closing the first opening/closing valve to stop the normal circulation of the cooling liquid and opening the second opening/closing valve to flow the pressurized fluid from the tank toward the sump screen. The backwash removes the debris that is blocking the sump screen, and suppresses the increase in pressure loss when the cooling liquid flows into the sump due to the accumulation of debris, and the safety system pump runs short of NPSH. The problem can be avoided.

The backwashing mechanism in the nuclear reactor equipment of the present invention has a simple structure in which a tank for backwashing fluid is attached to the existing cooling equipment such as pumps and circulation pipes in the conventional nuclear reactor equipment. Therefore, the present invention can be applied even when the arrangement condition is restricted.

Further, in the nuclear reactor equipment of the present invention, when the ordinary cooling liquid is temporarily stored in the tank and the blockage rate of the sump screen is increased, this cooling liquid is used as a pressurized fluid for backwashing. It is configured. Therefore, it is not necessary to supply the pressurized fluid from the outside every time the backwashing is performed, and it is possible to repeatedly perform the water discharge and the water filling of the tank, so that the cost increase due to the backwashing can be suppressed.

It is a longitudinal cross-sectional view of the reactor equipment according to the first embodiment of the present invention. (A)-(d) It is a figure explaining operation|movement of nuclear reactor equipment based on 1st embodiment of this invention.

Hereinafter, a reactor facility according to an embodiment to which the present invention is applied will be described in detail with reference to the drawings. Note that, in the drawings used in the following description, in order to make the features easy to understand, there may be a case where the featured portions are enlarged for convenience, and the dimensional ratios of the respective constituent elements are not necessarily the same as the actual ones. Absent. Further, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately modified and implemented without changing the gist thereof.

<First embodiment>
[Structure of reactor equipment]
The reactor equipment 100 according to the first embodiment of the present invention may be either a pressurized water type or a boiling water type, but the structure of the pressurized water type will be described below as an example. FIG. 1 is a vertical cross-sectional view schematically showing the configuration of a nuclear reactor facility 100 according to the first embodiment of the present invention. As shown in FIG. 1, the reactor equipment 100 mainly includes a reactor containment vessel (CV) 10, a recirculation pump equipment, a power generation equipment, and the like.

The reactor containment vessel 10 is provided with a reactor containment chamber 50 in which the reactor 51 is stored, and a recirculation pool chamber provided in the lower floor of the reactor containment chamber 50 and storing cooling water (cooling liquid) L ₁ therein. 60 (pressure adjusting pool chamber in case of boiling water type). An opening portion 70 is formed in a boundary portion (partition wall) 50A between the reactor containment chamber 50 and the recirculation pool chamber 60, and the opening portion 70 communicates with each other. A sump 61 is provided on the floor surface (bottom surface) 60A of the recirculation pool chamber, and the sump screen 32 is attached to the opening of the sump 61. In this embodiment, the case where one sump 61 is provided is illustrated, but the number of sumps 61 may be two or more.

The reactor containment vessel 10 according to the present embodiment is a cylindrical vessel having a dome-shaped top, and in addition to the reactor 51, a pressurizer 52 and a steam generator 53 are stored. The primary coolant (light water) is pressurized by the pressurizer 52 and further heated by the thermal energy generated by the nuclear fission reaction of the nuclear reactor 51. The high-temperature and high-pressure primary coolant is sent to the steam generator 53 to boil the secondary coolant (light water).

A turbine, a generator, and a condenser are provided outside the nuclear reactor containment vessel 10 as power generation equipment. The turbine rotates when the secondary coolant (steam) boiled by the steam generator 53 is sent, and the turbine is driven. The steam that has rotated the turbine is condensed in a condenser, becomes a secondary coolant, and is sent to the steam generator 53. In this way, the secondary coolant (light water) circulates between the steam generator 53, the turbine, and the condenser.

As shown in FIG. 1, the sump 61 is preferably provided on the floor surface 60A of the recirculation pool chamber at a position that does not overlap the opening 70 in a plan view from the reactor containment chamber 50 side. In this case, since the cooling liquid L that has flowed into the recirculation pool chamber 60 through the opening 70 flows into the sump 61 across the recirculation pool chamber 60, the occurrence of local retention is suppressed. You can

The recirculation pump facility sucks the cooling water L ₁ stored in the recirculation pool chamber 60 from the sump 61, guides it to the upper part of the reactor containment chamber 50, and discharges it into the reactor containment chamber 50 from there. It is configured. As a specific recirculation pump facility, for example, as shown in FIG. 1, a circulation pipe 21 arranged from the sump 61 to the ceiling of the reactor containment chamber 50, and a pump provided in the middle of the circulation pipe 21. 22 and a shower nozzle 23 provided on the ceiling of the reactor containment chamber 50. The pump 22 is attached to the circulation pipe 21 and has a function of pumping the cooling water L ₁ stored in the recirculation pool chamber 60 to the reactor containment chamber 50 side.

The cooling water L ₁ stored in the recirculation pool chamber 60 is pumped up from the sump 61 by the pump 22, passes through the pipe 21, and is discharged from the shower nozzle 23. Then, the cooling water L ₁ discharged from the shower nozzle 23 flows into the recirculation pool chamber 60 through the opening 70 after cooling the equipment stored in the reactor containment chamber 50. In this way, the cooling water L ₁ circulates among the sump 61, the pipe 21, the shower nozzle 23, the reactor containment chamber 50, and the recirculation pool chamber 60.

The recirculation pump facility is additionally provided with a backwash mechanism 20 that injects water L ₂ into the sump screen 32 from the side opposite to the normal time to backwash the sump screen. Backwash mechanism 20 mainly includes a tank 24 containing water L _2, a circulation pipe 21 functioning as a flow path of water L ₂ for backwashing, a pump 22 for pumping water L _2, the circulation pipe And a backwash pipe 25 that connects the tank 21 and the tank 24. In the following, the cooling water (cooling water, cooling liquid) L ₁ and the backwashing water L ₂ that flow into the reactor containment room 50 are respectively the first water L ₁ and the second water L _2. , But they are substantially the same liquid.

The circulation pipe 21 and the pump 22 are originally provided in the nuclear reactor facility 100 as a mechanism for circulating the cooling water as described above, and can be used together with the backwash mechanism 20. That is, the circulation pipe 21 is provided outside the reactor containment vessel 10, one end of which is connected to the recirculation pool chamber 60 and the other end of which is connected to the reactor containment chamber 50. The circulation pipe 21 has a first opening/closing valve 26 for adjusting the flow rate of the cooling water (first water) L _{1 in} a part thereof. The pump 22 is attached to a portion of the circulation pipe between the sump screen 32 and the first opening/closing valve 26.

The tank 24 is connected to a backwash pipe 25 branched from the circulation pipe 21. The backwash pipe 25 has a second opening/closing valve 27, and when opened, the second water L ₂ in the tank 24 flows out into the circulation pipe 21. ..

As shown in FIG. 1, the backwash pipe 25 has a branch point J between the tank 24 and the second opening/closing valve 27, and from this branch point J, a pipe 25A having a second opening/closing valve, and It may be branched to the pipe 25B which does not have two on-off valves. In this case, the branched pipes 25A and 25B are respectively connected to the circulation pipe 21, and the connection position A of the pipe 25A having the second opening/closing valve is larger than the connection position B of the pipe 25B having no second opening/closing valve. The position is close to the recirculation pool chamber 60.

Although FIG. 1 illustrates a case where there is one pipe 25A having the second on-off valve and one pipe 25B having no second on-off valve, the number of each is not limited. ..

As the tank 24, one having a capacity equal to or more than the entire volume of the sump screen for one train is used.

The tank 24 stores water for backwashing (second water) L ₂ , and as shown in FIG. 1, the lower end 24 a of the storage space is water for cooling the recirculation pool chamber 60 in the vertical direction V. It is installed so as to be located above the water surface L _1a .

By being installed in this way, the liquid level of the tank is at a position higher than the liquid level L _{1a of the} recirculation pool, and even after the pump 22 is stopped, the water drops in the tank head. Water is passed to the sump screen 32 side. That is, water can be passed without using the pump 22. It is preferable that the height difference between the liquid level in the tank and the liquid level L _{1a in the} recirculation pool is larger.

The water surface L _1a for cooling water in a normal state is adjusted so as to be in a predetermined position, and the position of the water surface L _{1a in} an accident is lower than this. If all the primary cooling water leaks, the water surface L _1a becomes the maximum water level.

2A to 2D are sectional views schematically showing the states of the reactor containment chamber 50 and the backwash mechanism 20 in the process of the backwash process. The operation of the backwash mechanism 20 will be described with reference to FIGS.

First, as shown in FIG. 2A, when the debris D is accumulated on the sump screen 32, the sump screen 32 is in a closed state, and the circulation of the cooling water L ₁ is delayed (the safety system pump The backwashing process is started at the time when a situation occurs where NPSH is insufficient. At this point, it is assumed that the tank 24 contains a sufficient amount of water L ₂ for backwashing. The degree of blockage of the sump screen 32 can be determined by monitoring the suction pressure of the pump.

When the sump screen 32 is closed, the pump 22 is stopped, the first opening/closing valve 26 is closed, and the circulation pipe 21 is shut off, so that the normal circulation of the cooling water L ₁ is stopped. At the same time that the circulation flow path is blocked, the second on-off valve 27 is opened and the backwash pipe 25 is opened, so that the backwash water L ₂ flows out from the tank 24.

Since the circulation of the normal cooling water L ₁ is stopped, as shown in FIG. 2B, the backwashing water L ₂ flowing out from the tank 24 to the circulation pipe 21 through the backwashing pipe 25. However, while cooling water L ₁ is pushed back, it flows backward in the circulation pipe 21 and is injected into the sump 61.

The injected backwashing water L ₂ concentrates on the sump screen 32 that is the only opening in the sump 61, and is discharged to the recirculation pool chamber 60 side through the sump screen 32. The debris D accumulated on the sump screen 32 floats up and is blown out (backwashed) into the recirculation pool chamber 60 due to the pressure when the backwash water L ₂ passes through the sump screen 32. As a result, The closed state of the sump screen 32 is eliminated, and a normal state in which normal cooling water L ₁ can be circulated (water flow) is achieved.

By closing the first opening/closing valve 26 and driving the pump 22, the circulation of the cooling water L ₁ is restarted. At this time, by closing the second opening/closing valve 27, in the initial stage after the circulation of the cooling water L ₁ is restarted, as shown in FIG. 2C, a part of the cooling water L ₁ is used for backwashing. The pipe 25 is filled (filled with water) through the pipe 25B that does not have the second on-off valve.

The pipe 25B having no second on-off valve is preferably provided with a check valve 28 attached so that water flows only in the direction from the circulation pipe to the tank. Further, in the pipe 25B having no second opening/closing valve, the amount of water L ₂ in the tank 24 is detected and automatically opened/closed so that the filling of water stops when the tank 24 is full. Three open/close valves (not shown) may be provided.

When the tank 24 has become full level, as shown in FIG. 2 (d), stops flow to the piping backwash water L ₁ for cooling, all piping circulating water L ₁ for cooling 21 And is sent to the reactor containment chamber 50. If the sump screen 32 is again blocked by the debris D, the backwash according to the above procedure is repeated.

As described above, the reactor equipment 100 according to the present embodiment includes the mechanism for backwashing the sump screen 32 when the blockage rate of the sump screen 32 due to the debris D becomes too high. To backwash the sump screen 32, the first opening/closing valve 26 is closed to stop the circulation of the normal cooling water L ₁ and the second opening/closing valve 25 is opened, so that the pressurized fluid flows from the tank 24 toward the sump screen 32. Is done. Since the debris D blocking the sump screen 32 is removed by backwashing, the increase of the pressure loss when the cooling water L ₁ flows into the sump 61 due to the accumulation of the debris D is suppressed, and the safety pump is used. It is possible to avoid the problem of shortage of NPSH.

The backwashing mechanism 20 in the reactor equipment 100 of the present embodiment has a simple structure in which a tank for backwashing fluid is attached to the existing cooling equipment such as pumps and circulation pipes in the conventional reactor equipment. This is applicable even when the arrangement conditions are restricted.

Further, in the reactor equipment of the present embodiment, normal cooling water is temporarily stored in the tank, and when the blockage rate of the sump screen increases, this cooling water is used as a pressurized fluid for backwashing. Is configured. Therefore, it is not necessary to supply the pressurized fluid from the outside every time the backwashing is performed, and it is possible to repeatedly perform the water discharge and the water filling of the tank, so that the cost increase due to the backwashing can be suppressed.

100... Reactor equipment 10... Reactor containment vessel 20... Backwash mechanism 21... Circulation pipe 22... Pump 23... Shower nozzle 24... Tank 25... Reverse Washing pipe 25A...Pipe 25B having second on-off valve...Pipe not having second on-off valve 26...First on-off valve 27...Second on-off valve 28...Check Valve 32... Sump screen 50... Reactor containment chamber 51... Reactor 52... Pressurizer 53... Steam generator 60... Recirculation pool chamber 60A... Floor 61. ... sample D ··· debris _L 1 ··· water for cooling (the first of water)
L ₂ ... Water for backwashing (second water)

Claims (6)

An atom having a reactor containment room for storing the reactor, and a recirculation pool room provided on the lower floor of the reactor containment room for storing the first water therein and having a sump screen on the floor surface A furnace containment vessel,
A circulation pipe provided outside the reactor containment vessel, having one end connected to the recirculation pool chamber via the sump screen and the other end connected to the reactor containment chamber, and having a first on-off valve. When,
A pump attached to a portion of the circulation pipe between the sump screen and the first on-off valve, capable of pumping the first water to the reactor containment chamber side;
A tank in which the second water is stored, and the lower end of the storage space is located above the water surface of the first water in the recirculation pool chamber in the vertical direction;
And a backwashing pipe having a second opening/closing valve for connecting the tank and the circulation pipe to each other. The backwash pipe is branched into a pipe having the second opening/closing valve and a pipe not having the second opening/closing valve, each of which is connected to the circulation pipe.
The reactor facility according to claim 1, wherein a connection position of the pipe having the second on-off valve is closer to the recirculation pool chamber than a connection position of the pipe not having the second on-off valve. .. The pump is connected to the circulation pipe at a position farther from the recirculation pool chamber than the connection position of the pipe having the second on-off valve. Reactor equipment described. 4. The pump according to claim 1, wherein the pump is connected to the circulation pipe at a position closer to the recirculation pool chamber than a connection position of the pipe not having the second opening/closing valve. The nuclear reactor facility according to any one of claims. The pipe having no second opening/closing valve has a third opening/closing valve that automatically opens/closes in accordance with the amount of the second water contained in the tank. The nuclear reactor facility according to any one of items 4 to 4. 6. The pipe having no second on-off valve has a check valve attached so that water flows only in a direction from the circulation pipe to the tank. The nuclear reactor facility according to any one of claims.

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