JPS59128491A - Method of cleaning up reactor cooling circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for purifying a reactor cooling system of a nuclear power plant, particularly a boiling water nuclear power plant.

[Technical background of the invention and its problems]

In a boiling water type nuclear power plant, a covered water storage tank is provided and is used for regulating surplus water and as a water source for a cooling system. This will be explained below with reference to FIG.

FIG. 1 is a schematic system diagram showing the flow of water around a conventional nuclear reactor.

A large number of control rod drive devices are installed at the bottom (a reactor containment vessel 2 is provided surrounding the sub-reactor pressure vessel 1. The inside of this reactor containment vessel 2 is connected to an upper reactor well 4a and a lower reactor well 4a. A partition wall 3 that divides the dry well 4b into two is provided.

A pressure suppression pool 5 is provided below the outside of the reactor containment vessel 2, and a reactor building 6 is provided surrounding it. A turbine 7 and a main condenser 8 are provided outside the reactor building 6, and the reactor pressure vessel 1 is connected to valves 10a and 10b.
.

A pipe 11 is provided from the upstream side of the valve 10 b, which is connected to the main steam pipe 9 via a valve 10 c, and which bypasses the turbine 7 and is connected to the main condenser 8 via a valve 12 . This main condenser 8 communicates with the turbine 7, and further includes a condensate pump 13, a condensate purification device 14, and a feedwater heater 15.1.
7. Boost pump 16a1 water supply pump 16b and valve 1
8 and is connected to the reactor pressure vessel 1 by a water supply pipe 19. Water supply tank with built-in condensate and water supply pipe 1
9 and piping 21 to the reactor pressure vessel 1, and via a make-up water pump 22 to the main condenser 8 via piping B. This condensate storage tank is connected to a control rod drive device, a control rod drive pump U, and a water pressure control unit 5 by a pipe 27a, and a return pipe 27b.
is also connected via the water pressure control unit δ to the waste treatment equipment with a drain pipe to the piping (pi) 29;
The condensate storage tank is connected to the condensate storage tank. In the reactor pressure vessel 1, a recirculation system consisting of a recirculation pump 31 and piping 32 for forcibly circulating the reactor core flow rate is provided in the reactor containment vessel 2. The mechanical seal portion of this recirculation pump 31 is provided with a pipe 33 that communicates with the waste treatment device path.

On the other hand, the pressure suppression pool 5 is connected to the reactor pressure vessel 1 by a pipe 36 via an emergency cooling pump 34 and a valve 35, and is also connected to the condensate storage tank addition to the suction side pipe of the emergency cooling pump U. In the upper part of the reactor building 6, there are
A fuel storage pool blade and a skimmer surge tank 39 connected thereto are provided, and a valve 40, a pump 41, a heat exchanger 42, and a purification device 43 are provided.
and by piping 44 connecting the reactor well 4a,
It constitutes a fuel storage pool cooling and purification system. Explain the effect of suki. Steam generated within the reactor pressure vessel 1 is sent to the turbine 7 through the main steam pipe 9, rotates the turbine 7, and is condensed in the main condenser 8. In some cases, it is condensed in the v1 main condenser 8 through a pipe 11 that bypasses the turbine. The water condensed in this way is pressurized by the condensate pump 13, purified by the rear water purifier ft14, and then a portion is returned to the condensate storage tank 2 through the pipe 21, and the remainder is sent to the feed water heater. 15.17, is pressurized by the booster pump 16a1 and the water supply pump 16b, and is returned to the reactor pressure vessel 1 through the water supply pipe 19.The control rod drive device 26 provided at the bottom of the reactor pressure vessel 1 During normal operation, the reactor is cooled by water in the condensate storage tank.This water flows into the reactor pressure vessel 1 through the control rod drive system.

During a reactor scram, waste water from the control rod drive device 26 is sent to a waste treatment device 28. In addition, a staging flow rate from the mechanical and mechanical seal portion of the recirculation pump 31 that forcibly circulates the coolant in the reactor is also sent to the waste treatment device path.

This water is purified here and returned to the condensate storage tank 20 for reuse, while the remaining water is discharged to a pipe 29 and taken out of the plant.

When replenishing water to the main condenser 8, the make-up water pump 22 supplies water to the condensate storage tank, and to replenish the condensate storage tank, water is pumped in from outside. There are other systems for this purpose.

The fuel storage pool cooling purification system includes a heat exchanger 41 and a purification device 4
2, the decay heat of the spent fuel is removed and the pool water is purified.

Furthermore, the pressure suppression pool 5 as part of the containment system includes:
Pool water is stored and absorbs the energy of the high-temperature, high-pressure coolant that is released in the event of a primary system piping rupture accident, and the pressure is increased by an emergency cooling pump bank and injected into the reactor pressure vessel 1 to cool the reactor core in an emergency. It functions as a water source. The water in the condensate storage tank 20 also functions as a water source.

However, this pressure suppression pool water is rarely used except in the case of loss of coolant accidents as mentioned above.
Contains radioactive materials such as sifrad due to periodic inspection of turbine-driven pump operation, equipment during reactor shutdown cooling system operation, piping warm-up and subsequent pump test, relief valve operation of main steam pipe 9, etc. If the reactor water flows in and accumulates for a long period of time, there is a risk that the radiation dose in the pressure suppression pool 5 and its surroundings will increase. Therefore, when water is injected into the reactor pressure vessel 1 during repair of equipment and piping or when the emergency core cooling system is activated, there is a risk that the reactor internal structures will also be adversely affected.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to quickly settle crud containing radioactive materials that flow into the suppression pool during test runs of reactor safety pumps, etc. A nuclear reactor in which solid matter is allowed to settle in the pressure suppression pool, and crud, etc. floating in the pool water is removed by the pressure suppression pool water cooling and purification system to obtain pressure suppression pool water as clean as condensate. A method for purifying a cooling system is provided.

[vA essentials of invention]

In order to achieve the above object, the present invention provides an emergency core cooling system and a fuel storage pool whose water source is at least the pool water stored in the pressure suppression pool out of the water stored in the condensate storage tank and the pressure suppression pool. In the method for purifying a reactor cooling system equipped with a fuel storage pool cooling and purifying system that cools and purifies pool water, the pressure suppression pool is provided with a pressure suppression pool water cooling and purification system, and the pressure suppression pool is equipped with a pressure suppression pool water cooling and purification system that cools and purifies the crud flowing into the pressure suppression pool. The crud that precipitates in the pressure suppression pool is left as is, and the floating crud is removed by the pressure suppression pool water cooling and purification system. The pressure suppression pool is composed of a plurality of segments, each segment is reinforced with a reinforcing ring, and its □ cross section is circular and has a donut shape as a whole, and is connected to a cooling water suction pipe. The discharge pipe is arranged at a position opposite to the pressure suppression pool. Furthermore, at least the heat exchanger and purification device in the pressure suppression pool water cooling system may be shared with the fuel storage pool cooling and purification system.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic system diagram showing the flow of water around a nuclear reactor according to an embodiment of the present invention. The same parts as in FIG. 1 will be described with the same reference numerals.

A reactor containment vessel 2 is provided surrounding a reactor pressure vessel 1, which has a number of control rod drive devices installed at its bottom. A partition wall 3 is provided that divides the inside of the reactor containment vessel 2 into an upper reactor well 4a and a lower dry well 4b.

A pressure suppression pool 5 is provided below the outside of the reactor containment vessel 2, and a reactor building 6 is provided surrounding it. A turbine 7 and a main condenser 8 are located outside the reactor building 6.
The reactor pressure vessel 1 is provided with valves 10a and 10b.

It is connected by main steam piping 9 via 10c.

A pipe 11 is provided from upstream of the valve 10b to bypass the turbine 7 and connect to the main condenser 8 via a valve 12. This main condenser 8 communicates with the turbine 7, and further includes a condensate pump 13, a condensate purification device 14, a feed water heater 15, 17,
The boost pump 16a1 is connected to the reactor pressure vessel 1 by a water supply pipe 19 via a water supply pump 16b and a valve 18, as in the conventional case. The pressure suppression pool 5 is connected to a control rod drive device, a control rod drive pump, and a pipe 27a that connects the water pressure control unit 5.
The return pipe 27b is also connected to the waste (5φ) treatment equipment side with a drainage pipe to the pit 29 via the water pressure control unit 6, and is further connected to the pressure suppression pool 5 between the pipes via the pump panel. In the reactor pressure vessel 1, a recirculation system consisting of a recirculation pump 31 and piping 32 for forcibly circulating the reactor core flow rate is provided in the reactor containment vessel 2.The mechanical seal portion of this recirculation pump 31 is A pipe 33 is provided which communicates with the waste treatment equipment path.

A skimmer surge tank 39 is provided in the upper part of the reactor room and is connected to the fuel storage pool side.
0, a pump 41, a heat exchanger 42, a purification device 43, and a pipe 44 connected to the reactor well 4a constitute a fuel storage pool cooling and purification system.

The pressure suppression pool 5 is connected to the reactor pressure vessel 1 by a pipe 36 via an emergency cooling pump 34 and a valve 35, and constitutes a normal core cooling system. Furthermore, outside the pressure suppression pool 5 are a pump 47, a heat exchanger 48, a purification device 49, piping for connecting these, a heat exchanger 48, and a purification device [
49'i A pressure suppression pool cooling and purification system consisting of a bypass pipe 51 is provided. The downstream side of the purification device 49 in this system is connected to the waste treatment device public through a valve 52 and a pipe 53. Further, the suction side of the pump 41 of the fuel storage pool cooling purification system and the pressure suppression pool 5 are connected by a pipe 45, and the downstream side of the purification device 14 of the water supply system is connected by a pipe 21. The pressure suppression pool 5 and the main condenser 8 are connected via a make-up water pump 22 with piping.

FIG. 3 is a system diagram showing details of the pressure suppression pool cooling and purification system of FIG. 2, and the same parts as in FIGS. 1 and 2 are given the same reference numerals for explanation.

A pump 47 is provided outside the pressure suppression pool 5 and a valve 55 is provided.
It is connected to the pressure suppression pool 5 via a piping device, and the piping (
The pressure suppression pool 5 is connected between the heat exchanger, the purification device 49, and the flow rate detection device, and the valves 57, 58, and 59.
0 heat converter 48 forming a closed loop returning to, piping 51 bypassing purifier 49 and valves 60a, 60b,
60c is provided. It is assumed that the valves 55 and 59 are automatically driven and have the function of isolation valves.

Furthermore, FIGS. 4 and 5 show details of the suction and discharge parts in the pressure suppression pool 5 of this system, and the same parts as in FIGS. 1 to 3 are given the same reference numerals and explained. In a Mark I reactor, the pressure suppression pool 5 has a donut shape with a circular cross section, as shown in Figure 5, and is composed of a plurality of segments, with a gap between each segment. A reinforcing ring 5a is provided. Since these reinforcing rings 5a are attached in the form of protrusions within the pressure suppression pool 5, contaminants that accumulate at the bottom of the pressure suppression pool 5 will accumulate in each segment and are not expected to migrate between them.

Experiments have shown that it is impossible to raise all of the contaminants such as crud that have settled at the bottom of the pressure suppression pool by water agitation, and that methods such as jet streams using high-pressure water are effective. However, purifying the pool water by blowing up all the contaminants such as crud accumulated at the bottom of the pressure suppression pool 5 using a jet stream of high-pressure water would waste a considerable amount of time and energy. Therefore, it is considered to be a better solution to remove the crud deposited at the bottom of the pool by other means, which is not practical. Therefore, contaminants such as crud that have settled at the bottom of the pressure suppression pool are excluded from the purification of the pool water, and the pool water is purified. To this end, the suction pipe 50a and the discharge pipe 50b may be provided on opposite sides of the pressure suppression pool 5, respectively, so that the entire amount of pool water is purified uniformly.

Next, the operation of the nuclear power plant of the present invention will be explained.

Steam generated within the reactor pressure vessel 1 is sent to the turbine 7 through the main steam pipe 9, rotates the turbine 7, and is condensed in the main condenser 8. In some cases, the water is condensed in the main condenser 8 through a pipe 11 that bypasses the turbine. The pressure of the condensed water is increased by the condensate pump 13 and purified by the condensate purifier 14. A portion of the water is returned to the pressure suppression pool 5 through the pipe 21, and the rest is heated by the feed water heaters 15 and 17. The water is then pressurized by the booster pump 16a1 and the water supply pump 16b and returned to the multi-reactor pressure vessel 1 through the water supply pipe 19. Also,
The control rod drive device installed at the bottom of the reactor pressure vessel 1 is cooled by pressure suppression pool water during normal reactor operation. This water flows into the reactor pressure vessel 1 through the control rod drive emplacement station.

The control rod drive device may be cooled by taking water from the downstream side of the condensate purification device 14 of the condensate water supply system. Also, during a reactor scram, drainage from the control rod drive device 26 is carried out through the pipe 2.
7b to the waste treatment equipment train. The staging flow rate from the mechanical seal part of the recirculation pump 31 that forcibly circulates the coolant inside the reactor is also sent to the waste treatment equipment, and this water is purified in this treatment equipment row.
It is returned to the pressure suppression pool 5 by the pump 54 for reuse, and the remaining water is discharged to the bit 29 and taken out of the plant.

In the fuel storage pool cooling and purification system, the pressure is increased by a pump 41 as in the past, and the pressure is returned to the fuel storage pool through a heat exchanger 42 and a purification device 43 to remove the decay heat of the spent fuel and purify the pool water. Further, in an emergency, the reactor core is cooled by injecting pressure suppression pool water into the reactor pressure vessel 1 through the pipe 36 using the pump 34. At the time of fuel exchange, the reactor well 4a is filled with water, and at that time, this system also injects pressure suppression pool water into the reactor pressure vessel 1 with the top lid removed.
Water flows into the reactor well 4a from the top to fill it with water.

Furthermore, when draining the reactor well 4a, the valve of the pipe communicating with the reactor well of the fuel storage pool cooling and purification system is opened, and the water is discharged to the pressure suppression pool 5 through the pipe 45. In either case, the reactor is shut down and the reactor core is filled with water, so there is no safety problem.

In the nuclear power plant with the above configuration, purification of water from the pressure suppression pool is carried out by increasing the pressure of the pressure suppression pool water with the pump 47, cooling and purifying it through the heat exchanger 48 and purification device 49, and returning it to the pressure suppression pool 5. Purify water. However, when purifying the pool water, it is necessary to close the lid to the pressure suppression pool 5.

Test runs of reactor safety pumps, which are a source of inflow of pollutants, are conducted approximately once a month, according to actual results.
Because reactor safety piping is mainly made of carbon steel, corroded crud flows into the pressure suppression pool once a month. It was found that more than 90% of the inflowing clad iron settles out in more than 10 hours, as shown in the results of the sedimentation test of pressure suppression pool water rad iron in FIG. 7. In addition, Fig. 8 shows the particle size distribution of crud in the pressure suppression pool water, which shows the particle size distribution of the crud collected at suitable locations A, BSC, D, and E in the pressure suppression pool. It is a diagram. From this research example, the majority of the particle sizes of the deposited crud are 3.
It can be considered that the particle size is larger than μ, and it is not easy to blow up crud of this size with the flow velocity of pressure suppression pool water. In order to process the crud, as shown in Figure 9, it is necessary to increase the flow rate in the pressure suppression pool to 2,500m4r or more in order to lift up the crud, and pumps from other systems do not match the capacity and cannot be shared. However, a pump with this capacity would have to be installed separately, resulting in a completely uneconomical power plant. Furthermore, even if it is installed separately, it is difficult to completely remove the deposited crud due to the influence of the structures within the pressure suppression pool.

For the above reasons, it is best to remove the deposited crud pipes and purify the pressure suppression pool water, and this purification is done using a purification device after the reactor safety system pump test run, which is carried out once a month. If this is done, clean pool water can be obtained in a short time with a small processing flow rate.

As an example, FIG. 10 shows a case where purification is performed using a purification device of a 1.3 million MWe class solvent storage pool cooling purification system.

Curve B shows that if the initial concentration of 2 rad in the pressure suppression pool water after a test run of the reactor safety system pump is 10-odd ppm, and if cleaning is started at the same time as settling starts, the pool will be clean in about 1 day. This shows that water can be purified, and curve A represents the purification time when all the inflowing crud is blown up in some way to purify it.9 It shows that it would take about 50 to 70 hours. For pool water purification, the suction pipe of the purification device installed in the pressure suppression pool should be set at the exact opposite position to the discharge pipe to prevent short paths of water within the pool water. To purify pool water uniformly in a short time.

According to the pressure suppression pool water purification method detailed above, by purifying the pool water by settling most of the inflowing crud, it is possible to achieve clean pool water that can be used as condensate. becomes. Therefore, there is no need to purify the pool water by blowing up the sedimentary crud with a huge amount of energy, and there is no need to treat the sedimentary crud at the bottom with the purification device, so the burden on the purification device is light. Furthermore, equipment costs, operating costs, and amount of waste generated for the purification device are minimized, making it possible to purify the pressure suppression pool with an overall inexpensive configuration. Furthermore, it is possible to purify pool water with a purification device for the fuel pool purification system, which requires less effort.In this case, all that is required is the additional setting of connection pipes, valves, and pumps for the pool water, and it can be used in existing plants. Pool water can be purified easily and inexpensively. In addition, it is preferable to periodically remove the crud deposited on the bottom by another means. In the above embodiment, the function of the condensate storage tank is combined with the pressure suppression pool, and the condensate storage tank is deleted. As explained above, it is of course possible to install the condensate storage tank as before without removing it and install a pressure suppression pool that also has the function of the condensate storage tank.In this case, there are advantages other than the above. , there will be multiple sources of clean water, further improving the safety of nuclear reactors.

Furthermore, it goes without saying that the condensate storage tank having conventional functions may be replaced by a pressure suppression pool having a pressure suppression pool water cooling and purification system.

FIG. 6 is a system diagram showing another embodiment of the pressure suppression pool cooling and purification system for a nuclear power plant according to the present invention, and the same parts as in FIGS. 1 to 5 will be described with the same reference numerals.

A skimmer surge tank 39 is provided in the upper part of the reactor building 6 and communicates with the fuel storage pool, and connects the pump 41, heat exchanger 42, purification device 43, and the reactor well 4a. Piping 44 and valve 40.40a
The structure of the fuel storage pool cooling and purification system is the same as in the past. On the other hand, there is a pressure suppression pool 5 provided below the reactor containment vessel 2, an auxiliary pump 62 and a fuel storage tank located outside of the suppression pool 5.

- Piping 6 connecting the suction side piping of the pump 41 of the cooling purification system
4 and valves 61, 63, and the fuel storage pool cooling and purifying system pump 41, heat exchanger 42, purifying device 43, and piping 68 connecting these and valves 65, 66, 67. A cooling purification system is provided. Additionally, the pump 41, heat exchanger 42, and purification device 43 of the fuel storage pool cooling and purification system are also shared by the pressure suppression pool cooling and purification system. Of course, the arrangement order of the pump 41, heat exchanger 42, and purifier 43 does not necessarily have to be as shown in the figure. Note that the auxiliary pump 62 may not necessarily be necessary due to the arrangement of the equipment.

In the fuel storage pool cooling and purification system, overflowing water from the fuel storage pool is passed through the weir to the skimmer surge pump 3.
9, is pressurized by a pump 41, cooled and purified by a heat exchanger 42 and a purifier 43, and returned to the fuel storage pool 3.
Returned to 8. On the other hand, the pressure suppression pool cooling and purification system allows the pressure suppression pool water to flow into the suction side of the pump 41 of the fuel storage pool cooling and purification system located several tens of meters above the ground.
The pressure is increased by the auxiliary pump 62. Then, the pressure is increased by a pump 41, and the temperature is cooled through a heat exchanger 42 and a purification device t43.
The purified pool water is returned to the pressure suppression pool 5.

Reactor water flows into the pressure suppression pool 5 when the turbine exhaust main steam relief safety valve for driving the pump of the emergency core cooling system is activated and when the reactor shutdown cooling system is started or stopped, and once the pressure is suppressed. If the pool water is purified, the pool water will not be contaminated by radioactivity as much unless the above devices are activated. On the other hand, the fuel storage pool cooling and purification system requires continuous operation immediately after fuel conversion to remove heat and purify the fuel storage pool. There is no need for continuous operation if the decay heat of the stored fuel discharged from the core at the weir 9 is reduced. Therefore, by combining both the emergency core cooling system and the fuel storage pool cooling and purification system and sharing some equipment, the systems can be rationalized without impairing the functions of both systems.

In addition, in this embodiment, the function of the condensate storage tank may be combined with the pressure suppression pool, and the condensate storage tank may be deleted, or both the condensate storage tank and the pressure suppression pool may be provided, and one of them may be used as a backup. It can also be used as a water source.

Although the present invention has been described above with reference to specific examples thereof, the present invention is not limited to these specific embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, the pool water can be purified by the purification system dedicated to the pressure suppression pool or the fuel storage pool cooling and purification system, so that the pool water becomes condensate with low radioactivity. This will reduce the dose rate in the surrounding area. Therefore, when repairing equipment and piping, etc. (7), the radiation exposure of workers is reduced, which in turn shortens the repair period and contributes to improving the operating rate of nuclear power plants. The amount of water in the pressure suppression pool is the same amount as the amount of water stored in the condensate storage tank.
By keeping the water in the pressure suppression pool clean at all times, the pressure suppression pool also has the functions of a condensate storage tank, making it possible to eliminate the condensate storage tank, which not only improves economic efficiency in terms of equipment. Compared to a double water storage tank that is open to the atmosphere, a pressure suppression pool is a closed container that is shielded from the atmosphere, including the reactor containment vessel, so the amount of harmful gases such as dissolved oxygen dissolved through piping, etc. is reduced. become. Even if the pressure suppression pool water is injected into the reactor pressure vessel by the emergency core cooling system or the like, since the quality of the pool water is controlled, it will not affect the internal reactor structures and will have almost no effect. Furthermore, by installing a heat exchanger in the purification system, it is possible to not only purify the pool water but also to cool it, making it possible to lower the pool water temperature to a possible temperature, which was previously limited by the rise in pool water temperature. Since nuclear reactors are no longer subject to these restrictions, the safety of nuclear reactors can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing the flow of water around a conventional nuclear reactor, FIG. 2 is a schematic system diagram showing the flow of water around a nuclear reactor according to an embodiment of the present invention, and FIG. Fig. 4 is a system diagram of the pressure suppression pool cooling and purification system shown in Fig. 3;
Fig. 5 is a sectional view of Fig. 4, Fig. 6 is a system diagram showing another embodiment of the pressure suppression pool cooling and purification system, and Fig. 7 shows the results of a sedimentation test of crud collected from the pressure suppression pool water. Figure 8 shows the particle size distribution results of crud collected from the pressure suppression pool water, and Figure 9 shows the flow rate in the pressure suppression pool when the crud deposited in the pressure suppression pool water is suspended. Figure 10, a diagram showing the relationship between crud particle size, shows the change in crud concentration in the pressure suppression pool when the pressure suppression pool was purified using the fuel storage pool purification system after a test run of the reactor safety pump. It is a diagram. l... Reactor pressure vessel, 2... Reactor containment vessel, 5
...Control rod driven pump, 6...Water pressure control unit,
But...control rod drive device, public...waste treatment device, 3
1... Recirculation pump, ah... emergency core cooling pump, seki... fuel storage pool, 39... skimmer surge tank, 41.45.47.62... pump, 42.
48...Heat exchanger, 43.49...Purification device. Fig. 3 Fig. 1I 6 Fig. 4 Fig. 5 Fig. m7 Fig. 8 Fig. 10, J 7:

Claims (3)

[Claims] (1) An emergency core cooling system whose water source is at least the pool water stored in the pressure suppression pool out of the water stored in the condensate storage tank and the pressure suppression pool, and fuel for cooling and purifying the pool water in the fuel storage pool. In the method for purifying a reactor cooling system equipped with a storage pool cooling and purification system, the pressure suppression pool is provided with a pressure suppression pool water cooling and purification system, and the crud flowing into the pressure suppression pool is precipitated in the pressure suppression pool. 1. A method for purifying a nuclear reactor cooling system, characterized in that the floating crud is left as is, and the floating crud is removed by the pressure suppression pool water cooling purification system. (2) The method for purifying a reactor cooling system according to claim 1, wherein at least the heat exchanger and the purification device in the pressure suppression pool water cooling purification system are shared with the fuel storage pool cooling and purification system. . (3) The pressure suppression pool is composed of multiple segments, each segment is reinforced with a reinforcing ring, and its cross section is circular, and the overall shape is donut-shaped. The method for purifying a nuclear reactor cooling system according to claim 1, wherein the suction pipe and the discharge pipe are arranged at opposing positions.