JP6210907B2 - PH control system for reactor containment - Google Patents

Description

  The present invention relates to a system for adjusting the pH in the reactor containment vessel in the event of an abnormality in the reactor contained in the reactor containment vessel, and in particular, by a pH adjuster effective in suppressing radioactive organic iodine, The present invention relates to a pH control system for a reactor containment vessel that regulates pH in a pressure suppression pool provided in the reactor containment vessel.

  As a type of a conventional nuclear power plant, one having a boiling water reactor (BWR) is known. In this nuclear power plant, the primary cooling system such as the reactor pressure vessel and the reactor recirculation system is stored in the reactor containment vessel, and the reactor containment vessel includes a dry well for storing the reactor pressure vessel and the pressure. It consists of a pressure suppression chamber with a suppression pool.

  Assuming that an abnormal event has occurred in the reactor and that the high temperature primary coolant has been released into the drywell, the discharged steam and water mixture is directed to a pressure suppression pool where the steam is cooled and condensed. As a result, an increase in the internal pressure of the reactor containment vessel can be suppressed. In addition, even if an abnormal reactor event is prolonged and the internal pressure of the containment vessel rises, the reactor containment vessel is prevented from being damaged by venting it from the pressure suppression chamber to the atmosphere. Can do. At this time, since the vent gas is a gas that has passed through the pressure suppression pool, it is possible to obtain a filter effect of the radioactive substance by water and to suppress the release of the radioactive substance from the system.

  In addition, the nuclear power plant is provided with facilities for spraying spray water into the reactor containment vessel. This is a facility for condensing steam with spray water to prevent pressurization of the reactor containment vessel when the reactor containment vessel is pressurized with steam due to loss of reactor coolant or the like. In a nuclear power plant equipped with a pressurized water reactor (PWR) as a reactor type, there is a facility for spraying an alkaline pH adjuster in a dry well to remove the generated organic iodine in order to remove iodine. It is known that it is installed (see Patent Document 1).

JP 2009-156895 A

  However, a method for injecting an iodine removing agent into a reactor containment vessel in a nuclear power plant equipped with a boiling water reactor (BWR) has not been established.

  In addition, the configuration of Patent Document 1 is that boric acid water as cooling water is pumped up by a spray pump, boric acid water is sprayed from directly above into a basket container containing the pH adjusting agent, and the pH adjusting agent is supplied to the reactor by an overflow method. It flows out into the containment vessel. Therefore, when an abnormal event occurs in the nuclear reactor and the AC power supply is lost, the spray pump cannot be driven, and it becomes difficult to spray the pH adjuster into the reactor containment vessel.

  The present invention provides a reactor containment vessel pH adjustment system capable of supplying a pH adjuster into a reactor containment vessel even in the event of an abnormality such as loss of an AC power supply.

In order to solve the above problems, the pH adjustment system of the present invention is a pH adjustment system disposed in a reactor building that houses a pressure suppression pool capable of storing cooling water and a reactor containment vessel that houses a reactor pressure vessel. A pH adjusting device having a pH adjusting agent tank for storing the pH adjusting agent and a pressurizing air cylinder connected to the pH adjusting agent tank via a compressed air supply pipe, and a flow of the pH adjusting agent A pH adjuster supply pipe for supplying to the pressure suppression pool, and the pH adjuster pressurizes the pH adjuster tank with compressed air from the pressurizing air cylinder and adjusts the pH with the compressed air. agent through a supply pipe provided with an air operated valve that allows injection of the pH adjusting agent to the pressure suppression pool, the air-operated valve, before provided in the compressed air supply pipe A pressurizing air operating valve that can pressurize the pH adjuster tank with compressed air, and a pH adjuster that is provided in the pH adjuster supply pipe and that allows the pH adjuster to be injected into the pressure suppression pool by the compressed air. It consists of an air operation valve for agent injection .

  According to the present invention, it is possible to reliably supply the pH adjuster into the reactor containment and remove organic iodine even in the event of an abnormality such as loss of AC power.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is the schematic of the nuclear reactor building provided with the pH adjustment system which concerns on embodiment of this invention. It is a schematic block diagram in the nuclear reactor containment vessel shown in FIG. It is a block diagram of the pH adjustment system which concerns on one Example of this invention. It is a block diagram of the pH adjustment system which concerns on the other Example of this invention. It is a block diagram of the pH adjustment system which concerns on the other Example of this invention. It is a block diagram of the pH adjustment system which concerns on the other Example of this invention.

  In FIG. 1, the schematic of the nuclear reactor building provided with the pH adjustment system which concerns on embodiment of this invention is shown. Below, the reactor building provided with the boiling water reactor (BWR) as a reactor building is demonstrated. As shown in FIG. 1, the reactor building 1 includes a fuel exchanger 7 on the ceiling, an operation floor (operating floor) 2, a spent fuel pool 3 immediately below the operation floor 2, a spent fuel temporary storage pool 6, A reactor containment vessel 10 and other safety-related devices (not shown) are provided. The reactor containment vessel 10 supplies steam generated from the reactor pressure vessel 11, the dry well 19, the pressure suppression chamber (wet well) 13 having the pressure suppression pool 14, and the reactor pressure vessel 11 to a turbine (not shown). Main steam supply pipe 4 and cooling water supply pipe 5 for supplying cooling water (for example, boric acid water or pure water) supplied from a condenser (not shown) to the reactor pressure vessel 11. The

  Also, in the reactor pressure vessel 11, a core loaded with a plurality of fuel assemblies (not shown), a plurality of control rods that can be inserted into the core to control the nuclear reaction of the fuel assemblies, and a fuel assembly at the top of the core A vapor-liquid separator that separates vapor generated by the nuclear reaction into a gas-liquid two-phase, and a vapor dryer is provided above the gas-liquid separator. In the fuel assembly, fuel rods in which a plurality of fuel pellets (for example, MOX fuel) are filled in a stainless clad tube are arranged in a square lattice pattern in a channel box having a rectangular cross section.

  The reactor pressure vessel 11 is filled with cooling water, and the cooling water enters the core from the lower part of the core through the cooling water supply pipe 5, rises along the fuel assembly, and is bundled in the fuel assembly. It is heated by the nuclear reaction by the fuel rod, and rises as steam containing moisture. The steam containing moisture is separated into a liquid phase and a gas phase by the gas-liquid separator, and further dried by the steam dryer to remove moisture. The steam after drying is supplied to the turbine through the main steam supply pipe 4, drives the turbine, and is generated by a generator connected to the turbine. The steam used for power generation is condensed into water by a condenser, and then is pressurized by a feed water pump (not shown) and circulated and supplied to the reactor pressure vessel 11 through the cooling water supply pipe 5 again.

  The upper space of the spent fuel pool 3 is covered with a relatively robust roof structure made of reinforced concrete or steel plate concrete having a wall thickness of 1.5 m or more, for example. In addition, the fuel exchanger 7 is used for removing the spent fuel assembly from the core and transferring it to the spent fuel pool 3 and inserting the fuel assembly into the core.

  Further, as shown in FIG. 1, a pH adjusting device 20 is installed on the operation floor 2 in the reactor building 1, and for example, a pH adjusting agent such as a sodium hydroxide solution is added to the pressure suppressing pool 14 in the pressure suppressing chamber 13. A pH adjusting agent supply pipe 29 for supplying to is provided. The pH adjusting device 20 includes a pressurizing air cylinder 22 described later, and pressure-feeds the pH adjusting agent to the pH adjusting agent supply pipe 29 by compressed air from the pressurizing air cylinder 22. The pH adjustment system of the present invention includes a pH adjuster 20 and a pH adjuster supply pipe 29. Thus, the pH adjustment system of the present invention does not require a pump or the like for pumping the pH adjuster. Therefore, even if the AC power source is lost in the event of an abnormality (when the power source is lost), the pH adjuster can be supplied to the pressure suppression pool 14. The installation location of the pH adjusting device 20 is not limited to the operation floor 2, and may be another location within the reactor building 1 and outside the reactor containment vessel 10.

  FIG. 2 shows a schematic configuration diagram in the reactor containment vessel 10 shown in FIG. As shown in FIG. 2, as described above, the reactor containment vessel 10 includes the reactor pressure vessel 11, the dry well 19, and the pressure suppression chamber 13. In normal operation, steam is sent from the reactor pressure vessel 11 to the turbine via the main steam supply pipe 4 to generate electricity. Here, when some abnormality occurs in the reactor and the internal pressure of the reactor pressure vessel 11 suddenly increases, the inside of the reactor pressure vessel 11 needs to be depressurized. Therefore, the relief safety valve 17 is provided in a pipe branched from the middle of the main steam supply pipe 4. The steam exhausted from the relief safety valve 17 is guided to the pressure suppression pool 14 in the pressure suppression chamber 13 through the pipe, where the steam is cooled and condensed. Thereby, the reactor pressure vessel 11 can be effectively depressurized. Further, although the vent gas contains a radioactive substance, it is possible to expect a water filter effect by ventilating the water in the pressure suppression pool 14 and to prevent diffusion of the radioactive substance. .

  Further, when a pipe containing primary cooling water such as a reactor cooling water recirculation system or a reactor cooling water purification system (not shown) is broken, a mixture of steam and water is released into the dry well 19. In this case as well as the relief safety valve 17, the discharged steam and water mixture is guided into the pressure suppression pool 14 by the dry well vent pipe 18. As shown in FIG. 2, the water in the pressure suppression pool 14 is pumped out by an ECCS (Emergency Core Cooling System) pump 16, and a spray facility 12 having a plurality of spray nozzles via an ECCS pipe 8. Is sprayed into the pressure suppression chamber 13.

Further, when the abnormal event is prolonged, the reactor containment vessel 10 is depressurized, so that it can be released from the reactor containment vessel vent pipe 15 to the atmosphere. In this case, since the filter effect of the water in the pressure suppression pool 14 described above can be expected, the release of radioactive material to the atmosphere is suppressed as low as possible. However, at this time, the vent gas introduced into the pressure suppression pool 14 from the relief valve 17 and the dry well vent pipe 18 is condensed by the water in the pressure suppression pool 14 and organic iodine, which is a radioactive substance contained in the vent gas, is condensed. It will remain in the water. However, the organic iodine remaining in the water is removed by the pH adjuster supplied from the pH adjuster 20 to the pressure suppression pool 14 via the pH adjuster supply pipe 29.

  Hereinafter, a pH adjustment system according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 3, the block diagram of the pH adjustment system which concerns on one Example of this invention is shown. As shown in FIG. 3, the pH adjusting device 20 includes a pH adjusting agent tank 21, a pressurizing air cylinder 22, a pressure reducing valve 23, a pressurizing air operating valve 24, and a pH adjusting agent injection air operating valve 25. In the pH adjuster tank 21, an alkaline aqueous solution such as a sodium hydroxide solution or a potassium hydroxide solution is stored as a pH adjuster. The pH adjusting device 20 supplies the pH adjusting agent to the pressure suppression pool 14 from the compressed air supply pipe 28 and the pH adjusting agent tank 21 for supplying the compressed air from the pressurizing air cylinder 22 to the pH adjusting agent tank 21. A pH adjusting agent supply pipe 29 is provided.

  In the compressed air supply pipe 28, the pressure reducing valve 23 for adjusting the pressure of the pH adjusting agent tank 21 and the addition of the pH adjusting agent tank 21 are sequentially arranged from the pressurizing air cylinder 22 side for pressurizing the pH adjusting agent tank 21. A pressurizing air actuated valve 24 for starting the pressure is provided. The pH adjusting agent supply pipe 29 is provided with a pH adjusting agent injecting air operating valve 25 for starting injection of the pH adjusting agent. In order to enable the pH adjusting device 20 of this embodiment to operate even when the AC power supply is lost, the pH adjusting agent injection valve and the pH adjusting agent pressurizing valve are air operated valves. As the air operated valve, for example, a diaphragm type air operated valve or a cylinder type air operated valve is used.

  Compressed air having a flow rate and pressure corresponding to the opening degree of the pressure reducing valve 23 and the pressurizing air operating valve 24 flows into the pH adjusting agent tank 21 from the compressed air supply pipe 28 and is stored in the pH adjusting agent tank 21. The adjusting agent is pushed out to the pH adjusting agent supply pipe 29. At this time, the pH adjusting agent injection air operation valve 25 is driven in conjunction with the pH adjusting agent, flows through the pH adjusting agent supply pipe 29 and is injected into the pressure suppression pool 14. The pH adjusting agent supply pipe 29 is provided with a first check valve 26 and a second check valve 27. Even if the internal pressure of the pressure suppression chamber 13 rises, the pH adjusting agent It is possible to prevent backflow. In the present embodiment, two check valves are provided. However, the present invention is not limited to this, and one check valve may be provided.

  The activation of the pH adjustment system of the present embodiment is manually activated at the discretion of the operator when the reactor core damage (not shown) is found out. Further, even when no core damage has occurred, it may be activated proactively.

  According to this embodiment, even when an abnormality such as loss of AC power supply occurs, the pH adjusting agent can be supplied to the pressure suppression pool 14 by compressed air, and organic iodine remaining in the water in the pressure suppression pool 14 is removed. Is possible.

  FIG. 4 shows a configuration diagram of a pH adjustment system according to another embodiment of the present invention. The same components as those shown in FIG. 3 are denoted by the same reference numerals. In the first embodiment, the pH adjusting agent is directly poured into the pressure suppression pool 14 from the pH adjusting device 20 through the pH adjusting agent supply pipe 29. However, in the present embodiment, the existing ECCS pipe 8 and the spray equipment 12 are used. The point which set it as the structure which pours into the pressure suppression pool 14 via is different from Example 1. FIG. Hereinafter, the description of the same configuration as that of the first embodiment will be omitted, and only different points will be described.

  As shown in FIG. 4, in the pH adjustment system of the present embodiment, the end of the pH adjusting agent supply pipe 29 provided with the first check valve 26 and the second check valve 27 is connected to the ECCS pipe 8. It is configured to connect on the way. In a state where the AC power supply is secured and the ECCS pump 16 can be started, the water in the pressure suppression pool 14 pumped out by the ECCS pump 16 is mixed with the pH adjuster in the ECCS pipe 8 and is supplied via the spray equipment 12. It is sprayed in the pressure suppression pool 14.

  Even if the AC power supply is lost and the ECCS pump 16 cannot be started, the pH adjuster flows into the ECCS pipe 8 and is sprayed into the pressure suppression pool 14 via the spray facility 12. Thereby, the organic iodine which remains in the water in the pressure suppression pool 14 can be removed.

  According to the present embodiment, in addition to the effects of the first embodiment, as shown in FIG. 2, the end of the pH adjusting agent supply pipe 29 is connected to the ECCS pipe 8 laid outside the reactor containment vessel 10. Therefore, it is possible to reduce the number of through portions to the reactor containment vessel 10. Moreover, since it is sprayed by the spray equipment 12, it becomes possible to inject the pH adjuster into the pressure suppression chamber 13 evenly (almost uniformly).

  FIG. 5 shows a configuration diagram of a pH adjustment system according to another embodiment of the present invention. The same components as those shown in FIGS. 3 and 4 are denoted by the same reference numerals. In the first embodiment, the compressed air is blown directly onto the liquid surface of the pH adjusting agent stored in the pH adjusting agent tank 21 via the compressed air supply pipe 28. However, in this embodiment, the pH adjusting agent tank is used. The second embodiment is different from the first embodiment in that a movable gas phase / liquid phase separation wall 31 is provided in 21. Since other configurations are the same as those of the first embodiment, description thereof will be omitted below.

  As shown in FIG. 5, the pH adjusting device 30 of the present embodiment includes a movable gas phase / liquid phase separation wall 31 in the pH adjusting agent tank 21 whose transverse section is equal to that of the pH adjusting agent tank 21. ing. A pH adjuster is stored below the gas phase / liquid phase separation wall 31. The compressed air introduced into the pH adjuster tank 21 from the compressed air supply pipe 28 moves the gas phase / liquid phase separation wall 31 downward. Thus, the stored pH adjusting agent is pushed out to the pH adjusting agent supply pipe 29 and injected into the pressure suppression pool 14. The gas phase / liquid phase separation wall 31 may have any configuration as long as the sealing property is maintained with the inner wall surface of the pH adjuster tank 21 with which the outer peripheral portion contacts, and the gas phase / liquid phase separation wall 31 can move in the vertical direction.

  According to the present embodiment, in addition to the effects of the first embodiment, dissolution of compressed air in the pH adjuster injected into the pressure suppression pool 14 is prevented. That is, since the gas phase is not mixed with the pH adjuster, stable injection is possible. As a result, it is possible to prevent the compressed air from the pressurizing air cylinder 22 from being excessively supplied into the pressure suppression chamber 13.

  FIG. 6 shows a configuration diagram of a pH adjustment system according to another embodiment of the present invention. The same components as those shown in FIGS. 3 to 5 are denoted by the same reference numerals. In contrast to the first embodiment, in this embodiment, the compressed air from the pressurizing air cylinder 22 can be used to drive the pressurizing air operating valve 24 and the pH adjusting agent injecting air operating valve 25 which are air operating valves. The point is different. Since other configurations are the same as those of the first embodiment, description thereof will be omitted below.

  As shown in FIG. 6, the pH adjusting device 40 of this embodiment is provided with a branch pipe between the pressurizing cylinder 22 and the pressure reducing valve 23 of the compressed air supply pipe 28, and the valve operating pressure reducing valve is provided in this branch pipe. 41 is provided. The pH adjusting device 40 includes a first three-way valve 43 for driving the pressurizing air operating valve 24, a second three-way valve 44 for driving the pH adjusting agent injecting air operating valve 25, and a first one. The three-way valve operating DC power source 42 for operating the three-way valve 43 and the second three-way valve is provided.

  When injection of the pH adjusting agent into the pressure suppression pool 14 is not necessary, the compressed air flowing through the branch pipes connected to the first three-way valve 43 and the second three-way valve 44 through the valve operating pressure reducing valve 41 is As shown by the arrows in FIG. 6, the gas is discharged from the first three-way valve 43 and the second three-way valve 44.

On the other hand, when the pH adjusting agent is injected into the pressure suppression pool 14, the compressed air flowing into the first three-way valve 43 is caused to flow toward the drive unit of the pressurizing air operating valve 24 by the three-way valve operating DC power supply 42. The path is switched, and the flow path is switched so that the compressed air flowing into the second three-way valve 44 is directed to the pH adjusting agent injection air operating valve 25. Thus, both when it drives the pressurizing pressurizing air operated valve 24 and a pH adjusting agent injection air operated valve 25 is air actuated valve with compressed air supplied from the air cylinder 22, compressing flowing through the compressed air supply pipe 28 Air flow rate and pressure are controlled.

  According to the present embodiment, in addition to the effects of the first embodiment, the pressurizing air operating valve 24 and the pH adjusting agent air operating valve 25 can be operated using only the compressed air of the pressurizing air cylinder 22. That is, the pH adjusting agent can be injected into the pressure suppression pool 14 only by the pressurized air cylinder 22.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace the configurations of other embodiments with respect to a part of the configurations of the embodiments.

DESCRIPTION OF SYMBOLS 1 Reactor building 2 Operation floor 3 Spent fuel pool 4 Main steam supply piping 5 Cooling water supply piping 6 Spent fuel temporary storage pool 7 Fuel changer 8 ECCS piping 10 Reactor containment vessel 11 Reactor pressure vessel 12 Spray equipment 13 Pressure Suppression room (wet well)
14 Pressure suppression pool 15 Reactor containment vessel vent pipe 16 ECCS pump 17 Relief safety valve 18 Dry well vent pipe 19 Dry well 20, 30, 40 pH adjuster 21 pH adjuster tank 22 Pressurizing air cylinder 23 Pressure reducing valve 24 Pressurizing air Operating valve 25 Air operating valve for injecting pH adjusting agent 26 First check valve 27 Second check valve 28 Compressed air supply piping 29 pH adjusting agent supply piping 31 Gas phase / liquid phase separation wall 41 Pressure reducing valve for valve operation 42 DC power supply for operation of three-way valve 43 First three-way valve 44 Second three-way valve

Claims (8)

A pH adjustment system disposed in a reactor building that houses a pressure containment pool that can store cooling water and a reactor containment vessel that houses a reactor pressure vessel,
a pH adjusting device having a pH adjusting agent tank for storing the pH adjusting agent and a pressurizing air cylinder connected to the pH adjusting agent tank via a compressed air supply pipe;
A pH adjuster supply pipe for passing the pH adjuster and supplying it to the pressure suppression pool,
The pH adjuster pressurizes the pH adjuster tank with compressed air from the pressurizing air cylinder and injects the pH adjuster into the pressure suppression pool via the pH adjuster supply pipe with the compressed air. With an air-operated valve to enable ,
The air operating valve is provided in the compressed air supply pipe and is capable of pressurizing the pH adjuster tank with the compressed air, and is provided in the pH adjuster supply pipe with the compressed air. A pH control system for a nuclear reactor containment vessel comprising an air-operated valve for injecting a pH adjuster that enables injection of the pH adjuster into the pressure suppression pool . In the reactor containment vessel pH adjustment system according to claim 1,
The cooling water in the pressure suppression pool flows through the outside of the pressure suppression chamber that houses the pressure suppression pool, and is supplied to the circulation piping that can be sprayed to the pressure suppression pool by a spray facility provided at the tip thereof. PCV for pH adjustment system characterized that you connect the ends of the adjusting agent supply pipe. In the reactor containment vessel pH adjustment system according to claim 1 ,
A gas phase / liquid phase separation wall is provided in the pH adjuster tank, and the gas phase / liquid phase separation wall is moved downward by compressed air flowing in through the compressed air supply pipe by the pressurizing air operation valve. it allows the pH adjusting agent containment vessel for pH adjustment system characterized Rukoto not release to the pH adjusting agent supply pipe a pH adjusting agent in the tank. The pH control system for a containment vessel according to claim 3 ,
A pH adjustment system for a reactor containment vessel , wherein a cross section of the gas phase / liquid phase separation wall is equal to a cross section of an inner wall surface of the pH adjuster tank . In the reactor containment vessel pH adjustment system according to claim 1 ,
The pH adjusting device is a first three-way valve capable of switching between a flow path for supplying compressed air from the pressurizing air cylinder to a drive unit of the pressurizing air operating valve and a flow path for discharging the compressed air. And a second three-way valve capable of switching between a flow path for supplying compressed air from the pressurizing air cylinder to a drive part of the air actuating valve for injecting the pH adjusting agent and a flow path for discharging the compressed air; A pH adjustment system for a reactor containment vessel, comprising: In the reactor containment vessel pH adjustment system according to claim 1 ,
A reactor containment vessel pH adjustment system , wherein a check valve is provided on the pressure suppression pool side of the pH adjuster supply pipe . The pH control system for a containment vessel according to claim 2,
A pH control system for a reactor containment vessel, comprising a check valve provided upstream of the pH adjuster supply pipe connected to the circulation pipe . The reactor containment vessel pH adjustment system according to any one of claims 1 to 7 , wherein the pH adjuster tank includes a sodium hydroxide solution or a potassium hydroxide solution as the pH adjuster. A pH control system for a containment vessel characterized by storing.

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