WO2022113512A1 - Excess pressure protection device for nuclear reactor housing vessel - Google Patents

Abstract

An excess pressure protection device (100) comprises: an emergency condenser (5) that is positioned outside of a nuclear reactor housing vessel (4) housing a nuclear reactor pressure vessel (1) therein, and causes steam produced in a reactor core to cool, condense, and revert to water; and an emergency condenser pool (9) that immerses the emergency condenser in water. The emergency condenser has a plurality of heat transmission pipes (15), an upper section header (14) that brings the upper end sides of the heat transmission pipes together, a lower section header (16) that brings the lower end sides of the heat transmission pipes together, a lower section header vent pipe (17a), one end section thereof being positioned near a bottom section within the emergency condenser pool and the other end section thereof being connected to the lower section header, and a lower section header vent (18a) that is positioned on the path of the lower section header vent pipe and is released when there is a decrease in water level that surpasses expectation within the nuclear reactor pressure vessel, or when there is an increase in pressure that surpasses expectation within the nuclear reactor housing vessel.

Description

Overpressure protection device for reactor containment vessel

INDUSTRIAL APPLICABILITY The present invention can prevent damage to the core and overpressure damage to the reactor containment vessel even if the emergency core cooling system loses its function in the event of a loss-of-coolant accident (LOCA). Regarding the overpressure protection device for the reactor containment vessel.

In the unlikely event of a loss of cooling material accident (LOCA) such as a main steam pipe breakage accident, the steam generated when cooling the core inside the reactor pressure vessel enters the reactor containment vessel via the breakage part of the pipe. It flows in and the pressure inside the reactor containment vessel rises.

In order to prevent overpressure damage to the reactor containment vessel, for example, in a boiling water reactor (BWR; Boiling Water Reactor), a small-sized wet reactor containment vessel is adopted. The wet reactor containment vessel is a pressure suppression pool filled with cooling water (pool water) by dividing the inside of the reactor containment vessel into a drywell area without cooling material and a pressure suppression chamber for storing cooling material. Is provided in the pressure suppression chamber as a liquid phase part. In the wet reactor containment vessel, the gas phase portion of the drywell region and the liquid phase portion (pressure suppression pool) of the pressure suppression chamber are connected by a plurality of vent pipes.

In the wet reactor containment vessel, the water vapor released into the drywell region when LOCA occurs is driven by the pressure difference between the drywell region and the pressure suppression chamber into the pressure suppression pool in the pressure suppression chamber via the vent pipe. Inflow. In the wet type containment vessel, the increase in pressure in the reactor containment vessel can be efficiently suppressed by condensing water vapor with pool water filled in the pressure suppression pool.

In addition, if LOCA continues, water vapor will flow out from the reactor pressure vessel, so the water level inside the reactor pressure vessel will drop, but the water level can be restored by injecting water using the emergency core cooling system. Therefore, damage to the core can be prevented.
In addition, as steam continues to flow into the pressure suppression pool inside the reactor containment vessel, the water temperature in the pressure suppression pool and the pressure inside the reactor containment vessel rise, but residual heat, which is one of the emergency core cooling systems, rises. By removing the heat from the pressure suppression pool water using the removal system, the pressure suppression pool water temperature and the pressure in the reactor containment vessel can be reduced, and as a result, overpressure damage of the reactor containment vessel can be prevented.

However, although it is an extremely rare event, it is conceivable that all emergency core cooling systems will lose their functions when LOCA occurs. Even if such an accident that exceeds the design standard (non-design standard accident) occurs, in order to prevent the accident from progressing to a serious accident (accident with core damage), the current BWR has equipment for dealing with serious accidents, etc. By taking measures to prevent overpressure damage of the containment vessel by injecting water into the core (reactor water injection) by the low-pressure alternative water injection system (reactor water injection) and by using the containment vessel pressure relief device (filter vent device), damage to the core and overload of the containment vessel Pressure damage can be prevented (for example, Patent Document 1).

Since the low-pressure alternative water injection system uses a pump, an alternative AC power supply is required as a power source, but as in Patent Document 2, reactor water injection can be realized only by controlling a valve that can be operated with a DC power supply (battery). , Means to prevent damage to the core are also known.

Japanese Unexamined Patent Publication No. 2016-186427 Japanese Unexamined Patent Publication No. 2010-112772

According to the technique described in Patent Document 1 described above, the gas inside the reactor containment vessel is discharged to the outside of the reactor containment vessel via a filter vent device having a radioactive substance removal function, whereby the environment of the radioactive material is obtained. It is possible to prevent overpressure damage of the reactor containment vessel while significantly suppressing the amount released to the reactor. However, the technique described in Patent Document 1 does not have a function of injecting water into the reactor pressure vessel, and in order to prevent damage to the core, such as the static water injection facility of the technique described in Patent Document 2 described above, It is necessary to add a separate water injection facility to the reactor pressure vessel.

On the other hand, according to the technique described in Patent Document 2 described above, by using static equipment that does not require an AC power supply, water injection into the reactor can be realized only by controlling a valve that can be operated by a DC power supply (battery), and the core is damaged. Can be prevented. However, the technique described in Patent Document 2 does not have a function of preventing overpressure damage of the reactor storage container, and in order to prevent overpressure damage of the reactor storage container, the technique described in the above-mentioned Patent Document 1 is used. It is necessary to add additional equipment to prevent overpressure damage to the reactor storage container.

The present invention has been made in view of the above background, and although it has a simple structure, even if the emergency core cooling system loses its function, the core is damaged or the reactor containment vessel is overpressured when LOCA occurs. The main purpose is to provide an overpressure protection device for the reactor containment vessel. The purpose of solving other problems will be appropriately described in the form for carrying out the invention.

In order to achieve the above object, the present invention is an overpressure protection device for a reactor containment vessel, which is arranged outside the reactor containment vessel containing the reactor pressure vessel and is included in the reactor pressure vessel. The emergency water recovery device is provided with an emergency water recovery device that cools and condenses the water vapor generated in the reactor core and returns it to water, and an emergency water recovery device pool that immerses the emergency water recovery device in water. Is a plurality of heat transfer tubes, an upper header that bundles the upper side of the heat transfer tube, a lower header that bundles the lower side of the heat transfer tube, and one end is near the bottom in the emergency water recovery vessel pool. When the water level drops more than expected in the reactor pressure vessel while being arranged and the other end is arranged on the path of the lower header vent pipe connected to the lower header and the lower header vent pipe. Alternatively, it is configured to have a lower header vent valve that is released when the pressure increases more than expected in the reactor storage vessel.
Other means will be described later.

According to the present invention, even if the emergency core cooling system loses its function even though it has a simple structure, it is possible to prevent damage to the core and overpressure damage to the reactor containment vessel when LOCA occurs.

It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 1st Embodiment. It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 2nd Embodiment. It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 3rd Embodiment. It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 4th Embodiment. It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 5th Embodiment. It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 6th Embodiment. It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 7th Embodiment. It is a system system diagram which shows the structure of the overpressure protection device of the reactor containment vessel which concerns on 8th Embodiment. It is a system system diagram which shows the structure of the modification of the overpressure protection device of the reactor containment vessel which concerns on 1st Embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiments”) will be described in detail with reference to the drawings. Each figure is merely schematically shown to the extent that the present invention can be fully understood. Therefore, the present invention is not limited to the illustrated examples. Further, in each figure, common components and similar components are designated by the same reference numerals, and duplicate description thereof will be omitted.

[First Embodiment]
<Structure of overpressure protection device for reactor containment vessel>
Hereinafter, the configuration of the overpressure protection device 100 of the reactor containment vessel 4 (PCV; Primary Containment Vessel) according to the first embodiment will be described with reference to FIG. 1. FIG. 1 is a system system diagram showing the configuration of the overpressure protection device 100 of the reactor containment vessel 4 according to the first embodiment.

As shown in FIG. 1, a reactor pressure vessel 1 (RPV; Reactor Pressure Vessel) containing a core 2 loaded with a plurality of fuel assemblies is installed inside the reactor containment vessel 4. The reactor containment vessel 4 is installed inside the reactor building 10. The reactor containment vessel 4 has high airtightness so that radioactive materials in the event of an accident can be trapped.

An emergency condenser 5 (IC; Isolation Condenser) is installed outside the reactor containment vessel 4 and inside the reactor building 10. In the emergency condenser 5, a plurality of heat transfer tubes 15 for cooling and condensing the water vapor generated in the core 2 and returning it to water are bundled by two upper and lower headers (upper header 14 and lower header 16). It is a header.

The emergency condenser 5 has an upper header 14, a heat transfer tube 15, and a lower header 16. The upper header 14 is connected to the gas phase portion of the reactor pressure vessel 1 (above the water level 3 (RPV water level) inside the reactor pressure vessel 1) by the steam suction pipe 6. The lower header 16 is connected to the gas phase portion or the liquid phase portion of the reactor pressure vessel 1 by the condensed water return pipe 7. Further, the lower header 16 is connected to the emergency condenser pool 9 by a lower header vent pipe 17a. One end of the lower header vent tube 17a is an opening.

The overpressure protection device 100 is arranged outside the reactor storage vessel 4 containing the reactor pressure vessel 1, and cools and condenses the steam generated in the core contained in the reactor pressure vessel 1 into water. It is provided with an emergency condenser 5 for returning and an emergency condenser pool 9 for immersing the emergency condenser 5 in water. In the emergency condenser 5, a plurality of heat transfer tubes 15, an upper header 14 for bundling the upper side of the heat transfer tube 15, a lower header 16 for bundling the lower side of the heat transfer tube 15, and one end thereof are used for emergency recovery. Reactor pressure located near the bottom of the condenser pool 9 and on the path of the lower header vent pipe 17a with the other end connected to the lower header 16 and the lower header vent pipe 17a. It has a lower header vent valve 18a that is released when the water level drops more than expected in the vessel 1 or when the pressure rises more than expected in the reactor containment vessel 4.

An emergency condenser start valve that is closed during normal operation on the path of the condensed water return pipe 7 and opens when it becomes necessary to remove heat from the core 2 during an abnormal transition during operation or in the event of an accident. 8 (IC start valve) is installed.

The emergency condenser 5 is immersed in the cooling water (pool water) of the emergency condenser pool 9 (IC pool).

The emergency condenser pool 9 is installed so that the bottom is higher than the water level 3 (RPV water level) inside the reactor pressure vessel 1. As a result, the emergency condenser pool 9 can send the pool water into the reactor pressure vessel 1 in the event of a Loss of Coolant Accident (LOCA).

On the path of the lower header vent pipe 17a, it is closed during normal operation, abnormal transition during operation, and design standard accident, and if necessary in the event of an accident exceeding the design standard accident (non-design standard accident). A lower header vent valve 18a that opens is installed.

The reactor building 10 is connected to the outside of the reactor building 10 via a gas exhaust line 11 and a stack 13 (exhaust stack). Unlike the reactor containment vessel 4, the reactor building 10 is not required to have a function of confining radioactive materials in the event of an accident in terms of design, but is usually designed conservatively so as to ensure a certain degree of airtightness.

Hereinafter, the operation of the overpressure protection device 100 according to the present embodiment when LOCA is generated due to the breakage of the main steam pipe 20 will be described. The following explanation targets accidents that exceed the design standard accidents (non-design standard accidents) in which the emergency core cooling system cannot be used.

When the main steam pipe 20 breaks, the high-temperature steam inside the reactor pressure vessel 1 flows out from the reactor pressure vessel 1 to the inside of the reactor containment vessel 4 through the break port, and the pressure of the reactor containment vessel 4 is reduced. The water level 3 (RPV water level) of the reactor pressure vessel 1 gradually decreases as the amount of water inside the reactor pressure vessel 1 gradually increases and decreases.

The emergency condenser start valve 8 is automatically started by a high pressure signal inside the reactor pressure vessel 1, a low water level signal inside the reactor pressure vessel 1, etc., and is automatically opened even when the power is lost. Because it is designed, it is a facility with extremely high start-up reliability.

Therefore, the following explanation will be given on the assumption that the emergency condenser 5 will be successfully started even in the event of an accident outside the design standards. When LOCA is generated and the water vapor inside the reactor pressure vessel 1 flows out to the reactor storage vessel 4, the water level 3 (RPV water level) inside the reactor pressure vessel 1 drops and the emergency condenser is activated. The valve 8 opens and the emergency condenser 5 starts.

By opening the emergency condenser start valve 8, the condensed water accumulated inside the emergency condenser 5 and the condensed water return pipe 7 is supplied to the reactor pressure vessel 1 and the steam drawing pipe 6 is connected. The water vapor inside the reactor pressure vessel 1 is drawn into the emergency condenser 5 through the heat transfer tube 15, and is condensed by the cooling water of the emergency condenser pool 9 in the heat transfer tube 15 to generate the water in the core 2. The decay heat can be discharged to the outside of the reactor containment vessel 4 (cooling water of the emergency condenser pool 9).

However, although the emergency condenser 5 can condense the water vapor of the reactor pressure vessel 1, water is injected into the reactor pressure vessel 1 from an external water source (water pool or the like) of the reactor storage vessel 4. You can't do it.

As the LOCA continues, the cooling water (steam) inside the reactor pressure vessel 1 continues to flow out to the reactor storage vessel 4 through the break port, so even after the emergency water recovery device 5 is started, the reactor The water level 3 (RPV water level) inside the reactor pressure vessel 1 continues to gradually decrease.

Since the pressure of the reactor pressure vessel 1 and the reactor containment vessel 4 can deheat the core 2 by the emergency water condensing device 5, that is, the inside of the reactor pressure vessel 1 and the reactor containment vessel 4 can be deheated. Depending on the heat removal capacity of the emergency water recovery device 5, the pressure rise rate of the reactor containment vessel 4 can be suppressed to some extent.

However, when the pressure inside the reactor pressure vessel 1 decreases, the water vapor density decreases and the heat removal performance of the emergency water recovery device 5 deteriorates. Therefore, even after the emergency water recovery device 5 is started, the reactor The pressure in the pressure vessel 1 and the reactor containment vessel 4 may continue to rise.

Should such a state continue, the core 2 will be exposed on the water surface, causing damage to the core 2, and the pressure inside the reactor containment vessel 4 will continue to rise, resulting in reactor containment. The containment vessel 4 may be overpressured and damaged.

Therefore, the overpressure protection device 100 according to the present embodiment automatically starts the emergency water recovery device start valve 8 by the pressure high signal inside the reactor pressure vessel 1 or the water level low signal inside the reactor pressure vessel 1. Or when the water level 3 (RPV water level) inside the reactor pressure vessel 1 becomes very low and the core 2 may be exposed, in addition to the function of the current emergency water recovery device that opens manually. Or, when the pressure inside the reactor storage container 4 becomes very high and there is a possibility that the reactor storage container 4 may be overpressured and damaged, the lower header vent valve 18a is used to increase the pressure inside the reactor storage container 4. Automatic start-up or manual opening by high signal (signal generated at a pressure higher than the high pressure signal) or low water level signal (signal generated at a water level lower than the low water level signal) inside the reactor pressure vessel 1. do.

That is, the overpressure protection device 100 is the cooling water (pool water) of the emergency condenser pool 9 (IC pool) when a loss of cooling material accident (LOCA) occurs and the emergency core cooling system cannot be used. The lower header vent valve 18a is opened in order to supply the reactor containment vessel 4.

Immediately after opening the lower header vent valve 18a, the lower header vent pipe 17a discharges gas in the reactor pressure vessel 1 to discharge water vapor containing radioactive substances into the cooling water (pool water) of the emergency condenser pool 9. Functions as a line. Then, after a while has passed since the lower header vent valve 18a was opened, the lower header vent pipe 17a serves as a cooling water supply line for supplying the cooling water (pool water) of the emergency condenser pool 9 to the reactor containment vessel 4. Function. This point will be described in detail below.

Immediately after opening the lower header vent valve 18a, the internal pressure of the reactor pressure vessel 1 is higher than the internal pressure of the reactor building 10. Therefore, the gas generated in the reactor pressure vessel 1 enters the emergency condenser 5 via the steam intake pipe 6 and the condensed water return pipe 7, and enters the emergency condenser pool 9 from the lower header vent pipe 17a. It is discharged. Therefore, at the initial stage of LOCA generation, the lower header vent pipe 17a functions as a gas discharge line for discharging the gas generated in the reactor pressure vessel 1 to the cooling water (pool water) of the emergency condenser pool 9. .. At this time, the cooling water (pool water) of the emergency condenser pool 9 is not sent from the emergency condenser pool 9 to the reactor containment vessel 4. That is, the cooling water (pool water) of the emergency condenser pool 9 is not supplied to the reactor pressure vessel 1. A part of the gas discharged to the emergency condenser pool 9 is guided to the stack 13 along the gas exhaust line 11 and discharged to the atmosphere through the stack 13. Further, the reactor pressure vessel 1 and the reactor containment vessel 4 are degassed, and the internal pressure drops.

Then, after a while from the opening of the lower header vent valve 18a, the reactor pressure vessel 1 is degassed, and the reactor pressure vessel 1 and the reactor storage vessel spatially connected via the LOCA break port are connected. The internal pressure of 4 decreases. At this time, due to the pressure difference between the pressure of the reactor pressure vessel 1 and the lower header vent pipe 17a opening in the water of the emergency water recovery device pool 9, the cooling water (pool water) of the emergency water recovery device pool 9 is lowered. It flows into the header vent pipe 17a and is sent from the emergency water condensate pool 9 to the reactor pressure vessel 1 via the lower header 16 and the condensed water return pipe 7. That is, the cooling water (pool water) of the emergency condenser pool 9 is supplied to the reactor pressure vessel 1. Therefore, after a while after the occurrence of LOCA, the lower header vent pipe 17a functions as a cooling water supply line for supplying the cooling water (pool water) of the emergency condenser pool 9 to the reactor pressure vessel 1. do.

By opening the lower header vent valve 18a, the water vapor inside the reactor pressure vessel 1 is released into the cooling water of the emergency condenser pool 9 through the lower header vent pipe 17a, and the inside of the reactor pressure vessel 1 is released. And the pressure inside the reactor storage vessel 4 spatially connected to the reactor pressure vessel 1 through the break port of the main steam pipe 20 can be reduced. Hereinafter, this function is referred to as "reactor containment vessel vent function". With this reactor containment vessel vent function, the overpressure protection device 100 can prevent overpressure damage of the reactor containment vessel 4.

When the pressure inside the reactor pressure vessel 1 drops sufficiently due to the outflow of water vapor inside the reactor pressure vessel 1 into the cooling water of the emergency condenser pool 9, emergency condenser water is restored from the lower header vent pipe 17a. The flow rate of water vapor discharged to the vessel pool 9 decreases, and the cooling water of the emergency condenser pool 9 begins to be injected into the reactor pressure vessel 1 as a gas-liquid counterflow while condensing the steam that continues to be discharged. Hereinafter, this function will be referred to as "reactor pressure vessel water injection function". With this reactor pressure vessel water injection function, the overpressure protection device 100 recovers the water level 3 (RPV water level) inside the reactor pressure vessel 1 and prevents the core 2 from being exposed on the water surface, thereby preventing the core 2 from being exposed to the water surface. Can prevent the occurrence of damage.

The water vapor discharged from the reactor pressure vessel 1 into the cooling water of the emergency condenser pool 9 contains activated structures inside the reactor (Co60, etc.) and some radioactive substances such as tritium water. Due to the effect of taking radioactive substances into the cooling water of the emergency condenser pool 9 (scrubbing effect), almost all of the radioactive substances are retained in the cooling water of the emergency condenser pool 9.

The radioactive material slightly discharged to the reactor building 10 is also diluted with the air inside the reactor building 10 and discharged from a high place to the outside of the reactor building 10 via the gas exhaust line 11 and the stack 13. It is possible to promote the diffusion of the exhausted gas and significantly suppress the increase in the local exposure amount.

In the conventional technique of this type, the reactor containment vessel 4 is for confining radioactive substances in the event of an accident, and even in the event of an accident outside the design standards, the reactor building 10 is filled with water vapor containing radioactive substances. Means of intentional discharge have not been considered.

On the other hand, in the overpressure protection device 100 according to the present embodiment, radioactive rare gas and fission products are contained in the reactor pressure vessel 1 and the reactor containment vessel 4 before the damage to the core 2 occurs. Before being released, the reactor containment vessel vent to the reactor building 10 having a certain degree of airtightness is carried out. As a result, the overpressure protection device 100 according to the present embodiment prevents damage to the core 2 and overpressure damage to the reactor containment vessel 4 in exchange for the release of a small amount of radioactive material, and radioactive rare gas and fission products. Can be excluded from the possibility of being released to the outside of the reactor containment vessel 4. The overpressure protection device 100 according to the present embodiment can reasonably reduce the amount of radioactive substances released to the outside of the reactor building 10 when an accident outside the design standard occurs.

By accumulating water vapor containing radioactive substances discharged from the lower header vent pipe 17a in another closed space (tank, etc.) having airtightness, the radioactive substances are released to the outside of the reactor building 10. Equipment configurations to prevent it are also conceivable. However, the equipment configuration is more complicated than that of the present embodiment, and problems occur due to human error, for example, overpressure damage of the tank and the reactor containment vessel 4 occurs due to erroneous closure of the emergency gas discharge line of the tank. Is a concern.

On the other hand, the overpressure protection device 100 according to the present embodiment has a simple configuration and can prevent damage to the core 2 and overpressure damage to the reactor containment vessel 4.

From the above, according to the overpressure protection device 100 according to the present embodiment, even when LOCA is generated and all the units of the emergency core cooling system fail (accidents outside the design standard), the water vapor inside the reactor pressure vessel 1 is extremely removed. The pressure inside the reactor pressure vessel 1 and the reactor containment vessel 4 is reduced by discharging the radioactive material into the cooling water of the water condenser pool 9, and the reactor containment vessel 4 is overloaded. In addition to preventing pressure damage, by injecting the cooling water of the emergency water condensate pool 9 into the reactor pressure vessel 1, it is possible to prevent the core 2 from being exposed on the water surface and prevent the core 2 from being damaged.
Due to the above two effects, the overpressure protection device 100 according to the present embodiment can prevent damage to the core 2 and overpressure damage to the reactor containment vessel 4 with a simple configuration.

In this embodiment, the pressure suppressing effect inside the reactor containment vessel 4 was explained for LOCA due to the breakage of the main steam pipe 20. However, the same effect can be obtained when another pipe (water supply pipe or the like) connected to the reactor pressure vessel 1 is broken.

Further, in the present embodiment, the description has been made using a vertical emergency condenser 5 in which the upper header 14, the heat transfer tube 15, and the lower header 16 are vertically connected. However, the same effect can be obtained with the horizontal type emergency condenser 5 using the U-shaped heat transfer tube.

[Second Embodiment]
Hereinafter, the configuration of the overpressure protection device 100A according to the second embodiment will be described with reference to FIG. 2. FIG. 2 is a system system diagram showing the configuration of the overpressure protection device 100A according to the second embodiment.

As shown in FIG. 2, the overpressure protection device 100A according to the second embodiment is different from the overpressure protection device 100 according to the first embodiment (see FIG. 1) in the following points.
(1) Similar to the lower header 16, the upper header 14 is also provided with a vent pipe and a vent valve (upper header vent pipe 17b and upper header vent valve 18b).
(2) The dynamic load suppressing devices 19a and 19b are installed at the openings of the lower header vent pipe 17a and the upper header vent pipe 17b to the emergency condenser pool 9 side.

In the overpressure protection device 100A according to the present embodiment, one end of the emergency condenser 5 is arranged inside the emergency condenser pool 9 at a position higher than the lower header vent pipe 17a, and the emergency condenser 5 is arranged at a position higher than the lower header vent pipe 17a. The other end is arranged on the path of the upper header vent pipe 17b connected to the upper header 14 and the upper header vent pipe 17b, and when the water level drops more than expected in the reactor pressure vessel 1 or the reactor is retracted. It has an upper header vent valve 18b, which is released when the pressure increases more than expected in the vessel 4.

At the initial stage of LOCA generation, both the lower header vent pipe 17a and the upper header vent pipe 17b discharge the gas generated in the reactor pressure vessel 1 to the cooling water (pool water) of the emergency condenser pool 9. Functions as a gas discharge line. Then, after a while after the occurrence of LOCA, the lower header vent pipe 17a functions as a cooling water supply line for supplying the cooling water (pool water) of the emergency condenser pool 9 to the reactor containment vessel 4. do. After that, when more time has passed since the occurrence of LOCA, the upper header vent pipe 17b also serves as a cooling water supply line for supplying the cooling water (pool water) of the emergency condenser pool 9 to the reactor containment vessel 4. Function. This point will be described in detail below.

For example, at the initial stage of LOCA generation, the internal pressure of the reactor pressure vessel 1 is higher than the internal pressure of the reactor building 10. Therefore, the gas generated in the reactor pressure vessel 1 enters the emergency condenser 5 via the steam intake pipe 6 and the condensed water return pipe 7, and passes through the emergency condenser 5 to the lower header vent pipe. It is discharged from the 17a and the upper header vent pipe 17b into the emergency condenser pool 9. Therefore, at the initial stage of LOCA generation, both the lower header vent pipe 17a and the upper header vent pipe 17b use the gas generated in the reactor pressure vessel 1 as the cooling water (pool water) of the emergency condenser pool 9. Functions as a gas discharge line to discharge. At this time, since the gas flow rate flowing out from the reactor pressure vessel 1 to the emergency condenser pool 9 is large, the cooling water (pool water) of the emergency condenser pool 9 cannot be supplied to the reactor pressure vessel 1. The gas discharged to the emergency condenser pool 9 is mixed with the air in the reactor building 10, and the gas in the reactor building 10 in which the amount of radioactive substances per unit volume is reduced by mixing is the gas. It is guided to the stack 13 along the exhaust line 11 and discharged to the atmosphere through the stack 13. Further, the reactor pressure vessel 1 and the reactor containment vessel 4 are degassed, and the internal pressure drops.

After a while after the occurrence of LOCA, the reactor pressure vessel 1 and the reactor containment vessel 4 are degassed, and the internal pressures of the reactor pressure vessel 1 and the reactor containment vessel 4 decrease. The lower header vent pipe 17a is arranged at a position lower (deeper in water) than the upper header vent pipe 17b in the emergency condenser pool 9. Therefore, one end (opening) of the lower header vent pipe 17a is subjected to a higher water pressure than one end (opening) of the upper header vent pipe 17b. Therefore, when the internal pressure of the reactor pressure vessel 1 becomes lower than the pressure applied to one end (opening) of the lower header vent pipe 17a, the pressure between the emergency water recovery device pool 9 and the reactor pressure vessel 1 Due to the difference, the cooling water (pool water) of the emergency water return device pool 9 flows into the lower header vent pipe 17a, and from the emergency water return device pool 9 to the reactor via the lower header 16 and the condensed water return pipe 7. It is sent to the pressure vessel 1. That is, the cooling water (pool water) of the emergency condenser pool 9 is supplied to the reactor pressure vessel 1. Therefore, after a while after the occurrence of LOCA, the lower header vent pipe 17a functions as a cooling water supply line for supplying the cooling water (pool water) of the emergency condenser pool 9 to the reactor pressure vessel 1. do. At this time, the upper header vent pipe 17b remains functioning as a gas discharge line.

In this state, the overpressure protection device 100A removes gas (steam containing radioactive substances) from the reactor pressure vessel 1 at the upper header vent pipe 17b, and atomizes from the emergency water condenser pool 9 at the lower header vent pipe 17a. Since the cooling water is supplied (injected) to the reactor pressure vessel 1, water can be quickly injected into the reactor pressure vessel 1.

After that, when a further time elapses after the occurrence of LOCA, the reactor pressure vessel 1 is further degassed, and the internal pressure of the reactor pressure vessel 1 further decreases. Then, when the internal pressure of the reactor pressure vessel 1 becomes lower than the pressure applied to one end (opening) of the upper header vent pipe 17b, not only the lower header vent pipe 17a but also the emergency water recovery device pool 9 The upper header vent pipe 17b, which is located higher than the lower header vent pipe 17a inside, is also a cooling water supply line that supplies the cooling water (pool water) of the emergency water recovery device pool 9 to the reactor pressure vessel 1. Functions as.

Further, in the overpressure protection device 100A according to the present embodiment, the emergency condenser 5 foams gas on one end of the upper header vent pipe 17b and one end of the lower header vent pipe 17a. It also has dynamic load suppressing devices 19a and 19b for discharging into the water of the emergency condenser pool 9. As the dynamic load suppressing devices 19a and 19b, for example, a quencher for miniaturizing water vapor bubbles or the like can be used.

When gas is discharged from the lower header vent pipe 17a and the upper header vent pipe 17b to the emergency condenser pool 9, a dynamic load is applied from the gas to the structure (wall or floor) of the emergency condenser pool 9. .. The structure (wall or floor) of the emergency condenser pool 9 may be damaged by its dynamic load.
Therefore, in the present embodiment, the dynamic load suppressing devices 19a and 19b are provided at one end (opening) of the lower header vent pipe 17a and the upper header vent pipe 17b. The dynamic load suppressing devices 19a and 19b atomize the gas discharged to the emergency condenser pool 9 into bubbles. As a result, the overpressure protection device 100A suppresses the dynamic load applied to the structure (wall or floor) of the emergency water return device pool 9 and becomes the structure (wall or floor) of the emergency water return device pool 9. You can reduce the damage done.

The overpressure protection device 100A according to the present embodiment can improve the following points as compared with the overpressure protection device 100 (see FIG. 1) according to the first embodiment.

In the first embodiment, the system configuration is simple because the water vapor is released from the reactor pressure vessel 1 and the cooling water is injected into the reactor pressure vessel 1 via one line (lower header vent pipe 17a). However, it takes a certain amount of time for the amount of water vapor discharged from the lower header vent pipe 17a to be sufficiently reduced, the gas-liquid countercurrent state to be realized, and the water injection into the reactor pressure vessel 1 to start.

On the other hand, in the overpressure protection device 100A according to the present embodiment, the upper header vent pipe 17b and the upper header vent valve 18b are newly provided in a place where the water depth of the emergency water recovery vessel pool 9 is shallow, so that the upper header vent can be vented. The release of water vapor inside the reactor pressure vessel 1 through the pipe 17b and the emergency to the reactor pressure vessel 1 via the lower header vent pipe 17a installed in a deep water of the emergency water recovery device pool 9. It is possible to inject the cooling water of the water recovery device pool 9 in parallel, and it is possible to accelerate the timing of injecting water into the reactor pressure vessel 1. As a result, the overpressure protection device 100A according to the present embodiment can improve the reliability of the damage prevention function of the core 2.

Further, in the overpressure protection device 100A according to the present embodiment, the dynamic load suppressing devices 19a and 19b are installed in the openings of the lower header vent pipe 17a and the upper header vent pipe 17b on the emergency condenser pool 9 side. Therefore, immediately after opening the lower header vent valve 18a and the upper header vent valve 18b, the high flow rate of steam discharged from the reactor pressure vessel 1 is emergency through the lower header vent pipe 17a and the upper header vent pipe 17b. It is possible to suppress the dynamic load applied to the structure (wall or floor) of the emergency condenser pool 9 when it is discharged into the cooling water of the condenser pool 9. Thereby, the overpressure protection device 100A according to the present embodiment can reduce the possibility of physical damage to the emergency condenser pool 9.

As described above, the overpressure protection device 100A according to the present embodiment has a higher reliability of the function of preventing damage to the core 2 by accelerating the timing of starting water injection into the reactor pressure vessel 1 as compared with the first embodiment. It is possible to improve the reliability of damage prevention of the emergency condenser pool 9 by suppressing the dynamic load when the water vapor of the reactor pressure vessel 1 is discharged into the cooling water of the emergency condenser pool 9. can.

[Third Embodiment]
Hereinafter, the configuration of the overpressure protection device 100B according to the third embodiment will be described with reference to FIG. FIG. 3 is a system system diagram showing the configuration of the overpressure protection device 100B according to the third embodiment.

As shown in FIG. 3, the overpressure protection device 100B according to the third embodiment is different from the overpressure protection device 100A according to the second embodiment (see FIG. 2) in the following points.
(1) The opening of the upper header vent pipe 17b on the emergency condenser pool 9 side is open above the water surface of the emergency condenser pool 9.
(2) The dynamic load suppressing devices 19a and 19b of the upper header 14 and the lower header 16 have been deleted.
(3) A collection filter 12 for collecting (removing) particulate radioactive substances is installed on the gas exhaust line 11.

In the overpressure protection device 100B according to the present embodiment, one end of the upper header vent pipe 17b is opened at a position above the water surface of the emergency condenser pool 9. Since one end (opening) of the upper header vent pipe 17b is located above the water surface of the emergency condenser pool 9, gas flows from the upper header vent pipe 17b to the reactor building 10. The influence of the dynamic load when being discharged can be reduced. Therefore, the overpressure protection device 100B can reduce damage to the structure (wall or floor) of the emergency condenser pool 9.

Further, in the overpressure protection device 100B according to the present embodiment, the overpressure protection device 100B collects particulate radioactive substances on the path for discharging the gas generated in the reactor pressure vessel 1 to the atmosphere. The collection filter 12 is provided. As the collection filter 12, for example, a charcoal filter can be used.

The overpressure protection device 100B according to the present embodiment can improve the following points as compared with the overpressure protection device 100A (see FIG. 2) according to the second embodiment.

In the overpressure protection device 100A according to the second embodiment, immediately after opening the lower header vent valve 18a and the upper header vent valve 18b, steam of the reactor pressure vessel 1 passes through the lower header vent pipe 17a and the upper header vent pipe 17b. It is discharged into the cooling water of the emergency condenser pool 9. Therefore, the overpressure protection device 100A according to the second embodiment improves the reliability of damage prevention of the emergency condenser pool 9 by installing the dynamic load suppression devices 19a and 19b at the tips of the respective pipes. ing.

On the other hand, in the overpressure protection device 100B according to the present embodiment, the amount of water vapor released from the upper header vent pipe 17b, which is not subject to the weight (head pressure) of the cooling water of the emergency condenser pool 9, becomes dominant. , The magnitude of the dynamic load generated when water vapor is released into the cooling water of the emergency condenser pool 9 is greatly suppressed. Therefore, the overpressure protection device 100B according to the present embodiment does not require the dynamic load suppressing devices 19a and 19b at the tip of each pipe, and can simplify the equipment configuration.

However, in the overpressure protection device 100B according to the present embodiment, since the water vapor of the reactor pressure vessel 1 is directly discharged into the internal space of the reactor building 10, the scrubbing effect of the cooling water of the emergency condenser pool 9 (Effect of removing radioactive substances) cannot be expected. Therefore, in the overpressure protection device 100B according to the present embodiment, by installing a collection filter 12 for removing particulate radioactive substances on the gas exhaust line 11, the gas is released into the internal space of the reactor building 10. The radioactive material is not released to the outside (atmosphere) of the reactor building 10 as much as possible.

As described above, the overpressure protection device 100B according to the present embodiment requires the addition of a collection filter 12 as compared with the overpressure protection device 100A (see FIG. 2) according to the second embodiment, but is an atom. By directly discharging the water vapor of the reactor pressure vessel 1 into the internal space of the reactor building 10, the dynamic load suppressing devices 19a and 19b at the tips of the respective pipes become unnecessary, and the equipment configuration can be rationalized.

[Fourth Embodiment]
Hereinafter, the configuration of the overpressure protection device 100C according to the fourth embodiment will be described with reference to FIG. FIG. 4 is a system system diagram showing the configuration of the overpressure protection device 100C according to the fourth embodiment.

As shown in FIG. 4, the overpressure protection device 100C according to the fourth embodiment is different from the overpressure protection device 100A (see FIG. 2) according to the second embodiment in the following points.
(1) A collection filter 12 for removing particulate radioactive substances is installed on the gas exhaust line 11.
(2) An emergency condenser pool 9 is provided with cooling water replenishment means 40 as equipment for replenishing cooling water.

In the overpressure protection device 100C according to the present embodiment, the overpressure protection device 100C includes a cooling water supply means 40 for supplying cooling water to the emergency condenser pool 9.

Further, in the overpressure protection device 100C according to the present embodiment, the cooling water replenishing means 40 replenishes the emergency water replenisher pool 9 with the replenishment water pool 21 for storing the cooling water to be replenished with the emergency water condensate pool 9. A backflow of cooling water from the make-up water pool 21 to the make-up water pool 21 arranged on the path of the make-up water pipe 23 connecting the water pool 21 and the emergency water return device pool 9 is provided. It has a make-up water pipe check valve 24 to prevent.

The bottom surface of the make-up water pool 21 is arranged at the same height as the bottom surface of the emergency condenser pool 9 or at a position higher than the bottom surface of the emergency condenser pool 9.

In such a configuration, when the cooling water of the emergency water recovery device pool 9 decreases when the LOCA occurs, the overpressure protection device 100C has a head of the cooling water of the emergency water recovery device pool 9 and the make-up water of the make-up water pool 21. Water flows from the make-up water pool 21 to the emergency water return device pool 9 due to the difference in pressure.

Such an overpressure protection device 100C can supply water from the make-up water pool 21 to the emergency condenser pool 9 by storing water (make-up water) in the make-up water pool 21.

Further, the overpressure protection device 100C supplies water to the make-up water pool 21 to inject cooling water from the outside of the reactor building 10 into the emergency condenser pool 9 and the inside of the reactor pressure vessel 1. be able to.

Such an overpressure protection device 100C according to the present embodiment can improve the following points as compared with the overpressure protection device 100A (see FIG. 2) according to the second embodiment.

In the overpressure protection device 100A according to the second embodiment, the cooling water (pool water) of the emergency condenser pool 9 is the lower header vent pipe 17a, although it depends on the amount of water stored in the emergency condenser pool 9. By injecting water into the reactor pressure vessel 1 via the above, the amount of water in the emergency condenser pool 9 may decrease, and the emergency condenser 5 and the upper header vent pipe 17b may be exposed on the water surface. .. When the upper header vent pipe 17b is exposed above the water surface, the scrubbing effect of the cooling water of the emergency condenser pool 9 cannot be expected, and although the amount is small, the radioactive material inside the reactor pressure vessel 1 is contained in the reactor building 10. There is a possibility that it will be released directly into the internal space of the reactor. It is possible to avoid such a situation by replenishing the emergency condenser pool 9 with cooling water using a fire engine or the like, but in the event of an accident outside the design standards, accessibility to the reactor building 10 deteriorates. Therefore, it may be difficult to replenish the cooling water by the fire engine.

On the other hand, in the overpressure protection device 100C according to the present embodiment, when the water level of the emergency condenser pool 9 drops, the water depth difference (water head pressure difference) between the emergency condenser pool 9 and the make-up water pool 21 is increased. As a driving force, the cooling water of the make-up water pool 21 is automatically supplied to the emergency condenser pool 9 via the make-up water pipe 23. As a result, the overpressure protection device 100C according to the present embodiment prevents the upper header vent pipe 17b from being exposed on the water surface, and maintains the scrubbing effect of the radioactive material by the cooling water of the emergency condenser pool 9. Can be done.

Further, in the overpressure protection device 100C according to the present embodiment, by arranging the make-up water pool 21 outside the reactor building 10 having good accessibility, cooling water can be replenished to the make-up water pool 21 by a fire truck or the like. Since it is easy, the scrubbing effect of the radioactive substance can be stably obtained for a long period of time.

Further, the overpressure protection device 100C according to the present embodiment is provided with the make-up water pipe check valve 24 on the path of the make-up water pipe 23, so that the cooling water of the emergency condenser pool 9 containing a small amount of radioactive material is replenished. It is possible to prevent the water from flowing out to the water pool 21 side.

Further, in the overpressure protection device 100C according to the present embodiment, since the scrubbing effect is maintained, almost all of the small amount of radioactive material released from the reactor pressure vessel 1 is held in the cooling water of the emergency condenser pool 9. However, the radioactive material released to the reactor building 10 that could not be completely removed due to the scrubbing effect is collected by the collection filter 12 before being discharged from the stack 13 via the gas exhaust line 11. (Remove. As a result, the overpressure protection device 100C according to the present embodiment can further reduce the amount of radioactive substances released to the outside of the reactor building 10 as compared with the overpressure protection device 100A according to the second embodiment.

As described above, the overpressure protection device 100C according to the present embodiment is provided with a make-up water pool 21 which is easier to replenish the cooling water than the second embodiment by providing the make-up water pool 21 outside the reactor building 10. Since the water level of the water reactor pool 9 can be maintained higher than that of the upper header vent pipe 17b, the scrubbing effect of radioactive substances by the cooling water of the emergency water reactor pool 9 can be continuously obtained, and it is removed by the scrubbing effect. Since the particulate radioactive substances that could not be removed can be collected (removed) by the collection filter 12, the amount of radioactive substances released to the outside of the reactor building 10 can be further reduced over a long period of time. ..

The make-up water pool 21 can also be installed inside the reactor building 10. In this case, the make-up water pipe check valve 24 becomes unnecessary.

[Fifth Embodiment]
Hereinafter, the configuration of the overpressure protection device 100D according to the fifth embodiment will be described with reference to FIG. FIG. 5 is a system system diagram showing the configuration of the overpressure protection device 100D according to the fifth embodiment.

As shown in FIG. 5, the overpressure protection device 100D according to the fifth embodiment is cooled to the emergency condenser pool 9 as compared with the overpressure protection device 100C (see FIG. 4) according to the fourth embodiment. The difference is that the equipment for replenishing water is provided with the cooling water replenishing means 40D instead of the cooling water replenishing means 40.

The cooling water replenishment means 40D includes a make-up water pool 21 for storing the cooling water to be replenished to the emergency water return device pool 9, a make-up water pipe 23 for connecting the emergency water return device pool 9 and the make-up water pool 21, and a make-up water pipe. It has a make-up water pump 22 which is arranged on the path of 23 and which overcomes the gravity difference and draws cooling water from the make-up water pool 21 and sends it to the emergency water return device pool 9.

The bottom surface of the make-up water pool 21 is arranged at a position lower than the bottom surface of the emergency condenser pool 9.

In such a configuration, the overpressure protection device 100D replenishes the water assembled from the make-up water pool 21 by the make-up water pump 22 to the emergency condenser pool 9 when LOCA occurs. In such an overpressure protection device 100D, the make-up water pool 21 can be installed at a place lower than the emergency condenser pool 9. A place lower than the emergency condenser pool 9 can easily secure a relatively large area. Therefore, the overpressure protection device 100D can increase the capacity of the make-up water pool 21.

Such an overpressure protection device 100D according to the present embodiment prevents the upper header vent pipe 17b from being exposed on the water surface, similarly to the overpressure protection device 100C (see FIG. 4) according to the fourth embodiment. The scrubbing effect of radioactive materials by the cooling water of the emergency condenser pool 9 can be maintained.

The make-up water pump 22 may be a permanent pump or a portable pump such as a fire engine.

[Sixth Embodiment]
Hereinafter, the configuration of the overpressure protection device 100E according to the sixth embodiment will be described with reference to FIG. FIG. 6 is a system system diagram showing the configuration of the overpressure protection device 100E according to the sixth embodiment.

As shown in FIG. 6, the overpressure protection device 100E according to the sixth embodiment is different from the overpressure protection device 100A according to the second embodiment (see FIG. 2) in the following points.
(1) A membrane filter (noble gas filter 25) that blocks radioactive rare gas and allows water vapor to permeate is installed in the opening of the gas exhaust line 11 on the reactor building 10 side.
(2) A static catalytic hydrogen recombination device 26 (PAR) is provided inside the reactor building 10 as a power supply-free facility for recombining hydrogen and oxygen to prevent a hydrogen explosion.

The overpressure protection device 100E according to the present embodiment includes a rare gas filter 25 that blocks radioactive rare gas and permeates water vapor on the path for discharging the gas generated in the reactor pressure vessel 1 to the atmosphere.

The overpressure protection device 100E has a rare gas filter 25. The rare gas filter 25 blocks radioactive rare gas and allows water vapor to pass through. As a result, the overpressure protection device 100E can reduce the amount of radioactive substances discharged into the atmosphere. As the rare gas filter 25, a polymer film such as polyimide, a ceramic film such as silicon carbide, a graphene oxide film, or the like can be used. These membranes have the property of allowing a gas having a small molecular diameter such as hydrogen or water vapor to permeate and not allowing a gas having a large molecular diameter such as xenon (Xe) to permeate. As shown in FIG. 6, the overpressure protection device 100E may have a collection filter 12 on the gas exhaust line 11 in addition to the noble gas filter 25.

Further, the overpressure protection device 100E according to the present embodiment is arranged in the reactor building 10 including the reactor containment vessel 4, and is a static catalytic hydrogen regeneration for recombining hydrogen and oxygen. A coupling device 26 is provided. The static catalytic hydrogen recombination device 26 does not require a power source and can bond hydrogen and oxygen by the action of a catalyst.

Such an overpressure protection device 100E according to the present embodiment can improve the following points as compared with the overpressure protection device 100A (see FIG. 2) according to the second embodiment.

In the overpressure protection device 100A according to the second embodiment, damage to the core 2 can be prevented by injecting the cooling water of the emergency condenser pool 9 into the reactor pressure vessel 1 via the lower header vent pipe 17a. Is. However, in the unlikely event that the decompression of the reactor pressure vessel 1 and the injection of the cooling water of the emergency water recovery device pool 9 are delayed and the core 2 is damaged, it is confined inside the fuel rod loaded in the core 2. The volatile fission products (Cs, etc.) and radioactive rare gas (Xe, etc.) that had been collected are discharged into the reactor pressure vessel 1, and at the same time, Zircaloy and high-temperature steam used as the cladding tube of the fuel rods. Hydrogen gas is generated inside the reactor pressure vessel 1 by the chemical reaction of.

When these gases are released into the cooling water of the emergency condenser pool 9 via the upper header vent pipe 17b, almost all of the volatile fission products such as Cs are in the emergency condenser due to the scrubbing effect. Although it is taken into the cooling water of the pool 9, the radioactive rare gas and hydrogen which are non-condensable gases are not taken in and are discharged to the reactor building 10.

Therefore, in the overpressure protection device 100E according to the present embodiment, the discharged hydrogen is recombined with oxygen contained in the air inside the reactor building 10 by the static catalytic hydrogen recombination device 26 to be water. Return to. As a result, the overpressure protection device 100E according to the present embodiment can prevent the occurrence of a hydrogen explosion in the reactor building 10.

Further, the overpressure protection device 100E according to the present embodiment is for preventing overpressure damage of the reactor building 10 and gas leakage from the reactor building 10 while holding the radioactive rare gas inside the reactor building 10. , A rare gas filter 25 is installed. The overpressure protection device 100E according to the present embodiment is a hydrogen and emergency water recovery device that cannot be completely processed by the static catalytic hydrogen recombination device 26, which is a pressurizing factor inside the reactor building 10. The water vapor and the like evaporating from the pool 9 can be selectively discharged from the reactor building 10, and the radioactive rare gas (Xe or the like) can be retained inside the reactor building 10.

As described above, the overpressure protection device 100E according to the present embodiment is volatile due to damage to the core 2 as compared with the overpressure protection device 100A (see FIG. 2) according to the second embodiment. Even if a situation occurs in which radioactive radioactive substances, radioactive rare gases, hydrogen, etc. are released to the reactor building 10 via the emergency water recovery device pool 9, the volatileness of the cooling water of the emergency water recovery device pool 9 occurs. It is possible to obtain the scrubbing effect of the radioactive substance, the hydrogen removing effect by the static catalytic hydrogen recombination device 26, and the confinement effect of the radioactive rare gas in the reactor building 10 by the rare gas filter 25. Therefore, the overpressure protection device 100E according to the present embodiment can reduce the possibility of hydrogen explosion inside the reactor building 10 and reduce the amount of radioactive substances released to the outside of the reactor building 10. ..

[7th Embodiment]
Hereinafter, the configuration of the overpressure protection device 100F according to the seventh embodiment will be described with reference to FIG. 7. FIG. 7 is a system system diagram showing the configuration of the overpressure protection device 100F according to the seventh embodiment.

As shown in FIG. 7, the overpressure protection device 100F according to the seventh embodiment is different from the overpressure protection device 100A (see FIG. 2) according to the second embodiment in the following points.
(1) The emergency condenser pool 9a has an airtight structure isolated from the reactor building 10.
(2) A gas exhaust line 11, a stack 13, and an emergency vent valve 27 for discharging the gas of the gas phase portion 30 of the emergency condenser pool 9a to the outside of the reactor building 10 in an emergency are provided.

In the overpressure protection device 100F according to the present embodiment, the emergency condenser pool 9a is a closed space having airtightness, and is in the reactor pressure vessel 1 in the emergency condenser pool 9a. A gas exhaust line 11 for discharging the generated gas to the atmosphere is provided.

Further, in the overpressure protection device 100F according to the present embodiment, the emergency condenser pool 9a is a closed space having airtightness, and is discharged from the reactor pressure vessel 1 to the emergency condenser pool 9a. It is possible to confine water vapor containing some radioactive substances in a closed space. Therefore, it is possible to completely prevent the release of radioactive substances to the outside. However, in the unlikely event that the core is damaged, a large amount of gas containing hydrogen is discharged from the reactor pressure vessel 1 to the emergency condenser pool 9a, which may cause overpressure damage to the emergency condenser pool 9a. If so, the overpressure protection device 100F is configured to discharge the gas in the emergency condenser pool 9a to the atmosphere along the gas exhaust line 11 via the stack 13. Therefore, an emergency vent valve 27 that is opened in an emergency is arranged on the gas exhaust line 11.

The emergency condenser pool 9a may be arranged inside the reactor building 10 or outside the reactor building 10. That is, the reactor building 10 may be configured such that the emergency condenser pool 9a is arranged inside as shown by the alternate long and short dash line, or the emergency condenser pool 9a may be arranged on the outside as shown by the alternate long and short dash line. The condenser pool 9a may be configured to be arranged.

The overpressure protection device 100F according to the present embodiment can improve the following points as compared with the overpressure protection device 100A (see FIG. 2) according to the second embodiment.

In the overpressure protection device 100A according to the second embodiment, a very small amount of radioactive material after being scrubbed by the cooling water of the emergency condenser pool 9a is released to the reactor building 10, and one of the very small amount of radioactive material. The unit is discharged from the stack 13 to the outside of the reactor building 10 via the gas exhaust line 11 connected to the reactor building 10.

On the other hand, in the overpressure protection device 100F according to the present embodiment, the emergency condenser pool 9a has an airtight structure, so that even a very small amount of radioactive material can be used in the gas phase portion of the emergency condenser pool 9a. It can be stored in 30. The overpressure protection device 100F according to the present embodiment can almost completely prevent the discharge of radioactive substances to the outside of the reactor building 10.

As described above, the overpressure protection device 100F according to the present embodiment is damaged by overpressure of the emergency condenser pool 9a by sufficiently securing the space volume of the gas phase portion 30 of the emergency condenser pool 9a. Can be prevented. Then, in the overpressure protection device 100F according to the present embodiment, there is a possibility that the pressure of the gas phase portion 30 of the emergency water recovery device pool 9a will exceed the maximum working pressure of the emergency water recovery device pool 9a. If there is, by opening the emergency vent valve 27, the gas in the gas phase portion 30 of the emergency water return device pool 9a is discharged to the outside of the reactor building 10 via the gas exhaust line 11 and the stack 13. Can be done. Thereby, the overpressure protection device 100F according to the present embodiment can prevent the overpressure damage of the emergency condenser pool 9a by any chance.

The radioactive substances can be discharged to the outside of the reactor building 10 by using a separate airtight tank instead of the emergency condenser pool 9a as the opening of the lower header vent pipe 17a and the upper header vent pipe 17b. Can be completely prevented. However, the overpressure protection device 100F according to the present embodiment can realize the same effect with a simpler configuration than such a configuration.

As described above, the overpressure protection device 100F according to the present embodiment has an atom by accumulating a very small amount of radioactive material in the gas phase portion 30 of the emergency condenser pool 9a as compared with the second embodiment. It is possible to almost completely prevent the discharge of radioactive substances to the outside of the reactor building 10.

Further, in the overpressure protection device 100F according to the present embodiment, there is a possibility that the pressure of the gas phase portion 30 of the emergency water recovery device pool 9a will exceed the maximum working pressure of the emergency water recovery device pool 9a. If there is, by opening the emergency vent valve 27, the gas in the gas phase portion 30 of the emergency water return device pool 9a is discharged to the outside of the reactor building 10 via the gas exhaust line 11 and the stack 13. You can also.

[Eighth Embodiment]
Hereinafter, the configuration of the overpressure protection device 100G according to the eighth embodiment will be described with reference to FIG. FIG. 8 is a system system diagram showing the configuration of the overpressure protection device 100G according to the eighth embodiment.

As shown in FIG. 8, the overpressure protection device 100G according to the eighth embodiment is in emergency use via the gas return line 28 as compared with the overpressure protection device 100F (see FIG. 7) according to the seventh embodiment. The difference is that the gas phase portion 30 of the condenser pool 9a and the reactor containment vessel 4 are connected.

The overpressure protection device 100G according to the present embodiment connects the gas phase portion 30 of the emergency condenser pool 9a and the reactor storage container 4, and is inside the gas phase portion 30 of the emergency condenser pool 9a. The gas return line 28 for returning the gas to the reactor storage container 4 and the gas return valve 29 arranged on the path of the gas return line 28 and opening and closing the gas return line are provided.

The overpressure protection device 100G according to the present embodiment has a gas return valve 29 installed on the gas return line 28. By adding these facilities, the overpressure protection device 100G according to the present embodiment is, for example, a dynamic heat removal facility for the reactor containment vessel 4 after a sufficient time has passed since the occurrence of an accident outside the design standard. When (heat removal equipment using a pump and heat exchanger) is restored and the pressure in the reactor containment vessel 4 is reduced, the gas return valve 29 is opened to open the gas phase of the emergency water return device pool 9a. The gas containing a small amount of radioactive material accumulated in the unit 30 can be returned to the reactor containment vessel 4 via the gas return line 28. Thereby, the overpressure protection device 100G according to the present embodiment can further reduce the possibility of overpressure damage of the emergency condenser pool 9a.

That is, if the accident is prolonged, there is a possibility that the heat removal equipment for cooling the reactor containment vessel 4 will be restored. Then, when the heat removal equipment is restored, the overpressure protection device 100G does not have to open the emergency vent valve 27. Such an overpressure protection device 100G can reduce the amount of gas released into the atmosphere, and thus the amount of radioactive substances.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. It is possible to replace a part of the configuration of the embodiment with another configuration, and it is also possible to add another configuration to the configuration of the embodiment. Further, it is possible to add / delete / replace a part of each configuration with another configuration.

For example, the overpressure protection device 100 (see FIG. 1) according to the first embodiment can be deformed as shown in FIG. FIG. 9 is a system system diagram showing a configuration of a modified example of the overpressure protection device 100 according to the first embodiment.

In the first embodiment described above, it is assumed that LOCA occurs and the emergency core cooling system does not operate as an accident outside the design standard of the boiling water reactor, and the pressure of the reactor containment vessel 4 is suppressed by the overpressure protection device 100. Explained the effect. However, the overpressure protection device 100 can obtain the same effect even in the case of an accident outside the design standard of another type of boiling water reactor having a different safety system configuration.

For example, as shown in FIG. 9, the overpressure protection device 100 is installed instead of the emergency core cooling system on the reactor pressure vessel 1 side of the LOCA break port and as close as possible to the reactor pressure vessel 1. The same effect can be obtained even when applied to a boiling water type light water reactor (reactor pressure vessel isolation type plant) provided with an RPV isolation valve 31 directly attached to the reactor pressure vessel 1.

In a reactor pressure vessel isolation type plant with such a configuration, when LOCA, which is a design standard accident, occurs, first, by closing the RPV isolation valve 31, the water vapor of the reactor pressure vessel 1 is released from the LOCA break port. Prevent it from flowing out to the reactor containment vessel 4. When the RPV isolation valve 31 is closed, the reactor pressure vessel 1 is isolated, so that the pressure inside the reactor pressure vessel 1 rises due to the steam generated in the core 2, and the water level 3 inside the reactor pressure vessel 1 ( RPV water level) drops. Therefore, the overpressure protection device 100 activates the emergency water recovery device 5 triggered by a high pressure signal inside the reactor pressure vessel 1, a low water level signal inside the reactor pressure vessel 1, or the like, and activates the reactor pressure vessel. The water vapor inside 1 is condensed and returned to water. As a result, the overpressure protection device 100 suppresses the pressure rise inside the reactor pressure vessel 1 and returns the condensed water to the reactor pressure vessel 1 to prevent damage to the core 2.

In addition, if an accident outside the design standard occurs in the reactor pressure vessel isolation type plant, that is, if the RPV isolation valve 31 fails to close, the situation is the same as the emergency core cooling system startup failure. That is, in this case, water vapor continuously flows out from the reactor pressure vessel 1 to the reactor containment vessel 4 from the LOCA break port, the pressure inside the reactor containment vessel 4 rises, and the reactor pressure vessel 1 The internal water level 3 (RPV water level) will continue to decline. Therefore, even in the case of a reactor pressure vessel isolated type plant, the overpressure protection device 100 suffers from damage to the core 2 and overpressure damage to the reactor containment vessel 4, similar to a boiling water reactor having an emergency core cooling system. Prevention can be realized.

1: Reactor pressure vessel (RPV)
2: Core 3: Water level (RPV water level)
4: Reactor containment vessel (PCV)
5: Emergency condenser (IC)
6: Steam lead-in pipe 7: Condensed water return pipe 8: Emergency condenser start valve (IC start valve)
9: Emergency condenser pool (IC pool)
10: Reactor building 11: Gas exhaust line 12: Collection filter 13: Stack (exhaust stack)
14: Upper header 15: Heat transfer tube 16: Lower header 17a: Lower header vent pipe 17b: Upper header vent pipe 18a: Lower header vent valve 18b: Upper header vent valve 19a, 19b: Dynamic load suppressing device 20: Main steam pipe 21 : Make-up water pool 22: Make-up water pump 23: Make-up water pipe 24: Make-up water pipe check valve 25: Rare gas filter 26: Static catalytic hydrogen recombination device (PAR)
27: Emergency vent valve 28: Gas return line 29: Gas return valve 30: Emergency condenser pool gas phase part 31: RPV isolation valve 40, 40D: Cooling water replenishment means 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G: Overpressure protection device

Claims (12)

1. An emergency condenser that is placed outside the reactor containment vessel that contains the reactor pressure vessel and that cools and condenses the water vapor generated in the core contained in the reactor pressure vessel and returns it to water.
   The emergency condenser pool, which immerses the emergency condenser in water, is provided.
   The emergency condenser is
   With multiple heat transfer tubes,
   An upper header that bundles the upper side of the heat transfer tube and
   A lower header that bundles the lower side of the heat transfer tube and
   A lower header vent pipe having one end located near the bottom of the emergency condenser pool and the other end connected to the lower header.
   A lower header vent valve arranged on the path of the lower header vent pipe and released when the water level drops more than expected in the reactor pressure vessel or when the pressure increases more than expected in the reactor containment vessel. An overpressure protection device for a reactor containment vessel characterized by having.
2. In the overpressure protection device for the reactor containment vessel according to claim 1.
   The emergency condenser is
   An upper header vent pipe having one end located higher than the lower header vent pipe inside or outside the emergency condenser pool and having the other end connected to the upper header.
   An upper header vent valve arranged on the path of the upper header vent pipe and released when the water level drops more than expected in the reactor pressure vessel or when the pressure increases more than expected in the reactor containment vessel. An overpressure protection device for a reactor containment vessel characterized by having.
3. In the overpressure protection device for the reactor containment vessel according to claim 2.
   In the emergency condenser, the gas generated in the reactor pressure vessel is foamed at one end of the upper header vent pipe and one end of the lower header vent pipe, and the emergency condenser is used. Condenser An overpressure protection device for a reactor containment vessel, characterized by having a dynamic load suppression device that discharges water into the pool.
4. In the overpressure protection device for the reactor containment vessel according to claim 2.
   An overpressure protection device for a reactor containment vessel, characterized in that one end of the upper header vent pipe is open above the water surface of the emergency condenser pool.
5. In the overpressure protection device for the reactor containment vessel according to claim 1.
   Further, overpressure protection of the reactor containment vessel is provided with a collection filter for collecting particulate radioactive substances on the path for discharging the gas generated in the reactor pressure vessel to the atmosphere. Device.
6. In the overpressure protection device for the reactor containment vessel according to claim 1.
   Further, an overpressure protection device for a reactor containment vessel, characterized in that the emergency condenser pool is provided with cooling water replenishment means for replenishing cooling water.
7. In the overpressure protection device for the reactor containment vessel according to claim 6.
   The cooling water replenishment means
   The make-up water pool that stores the cooling water to be replenished in the emergency condenser pool,
   A make-up water pipe connecting the emergency condenser pool and the make-up water pool,
   Overpressure of the reactor containment vessel arranged on the path of the make-up water pipe and having a make-up water pipe check valve for preventing the backflow of cooling water to be replenished to the emergency condenser pool. Protective device.
8. In the overpressure protection device for the reactor containment vessel according to claim 6.
   The cooling water replenishment means
   The make-up water pool that stores the cooling water to be replenished in the emergency condenser pool,
   A make-up water pipe connecting the emergency condenser pool and the make-up water pool,
   Overpressure of the reactor containment vessel arranged on the path of the make-up water pipe and having a make-up water pump that draws cooling water from the make-up water pool and sends it to the emergency condenser pool. Protective device.
9. In the overpressure protection device for the reactor containment vessel according to claim 1.
   Further, the overpressure of the reactor containment vessel is provided with a rare gas filter that blocks radioactive rare gas and allows water vapor to pass through the path for discharging the gas generated in the reactor pressure vessel to the atmosphere. Protective device.
10. In the overpressure protection device for the reactor containment vessel according to claim 1.
    The reactor containment vessel is located inside the reactor building containing the reactor containment vessel, and is provided with a static catalytic hydrogen recombination device for recoupling hydrogen and oxygen. Pressure protection device.
11. In the overpressure protection device for the reactor containment vessel according to claim 1.
    The emergency condenser pool is a closed space having airtightness, and is a gas exhaust for discharging the gas generated in the reactor pressure vessel in the emergency condenser pool to the atmosphere. An overpressure protection device for a reactor containment vessel comprising a line and providing an emergency vent valve on the gas exhaust line that opens when there is a risk of overpressure damage to an airtight closed space.
12. In the overpressure protection device for the reactor containment vessel according to claim 11.
    A gas return line for connecting the gas phase portion of the emergency condenser pool and the reactor storage container and returning the gas in the gas phase portion of the emergency condenser pool to the reactor storage container. When,
    An overpressure protection device for a reactor containment vessel, which is arranged on the path of the gas return line and includes a gas return valve for opening and closing the gas return line.

Images