JP7422058B2 - Overpressure protection device for reactor containment vessel - Google Patents

Description

The present invention makes it possible to prevent damage to the reactor core and overpressure failure of the reactor containment vessel even if the emergency core cooling system loses its function in the event of a loss-of-coolant accident (LOCA). This invention relates to an overpressure protection device for a reactor containment vessel.

In the unlikely event that a loss of coolant accident (LOCA) such as a main steam pipe rupture accident occurs, water vapor generated during the cooling of the reactor core in the reactor pressure vessel will enter the reactor containment vessel through the rupture of the piping. The pressure inside the reactor containment vessel increases.

In order to prevent overpressure damage to the reactor containment vessel, a small-sized wet type reactor containment vessel is used, for example, in boiling water reactors (BWRs). A wet type reactor containment vessel divides the inside of the reactor containment vessel into a dry well area with no coolant and a pressure suppression chamber that stores coolant, and a pressure suppression pool filled with cooling water (pool water). is provided in the pressure suppression chamber as a liquid phase part. The wet type reactor containment vessel connects the gas phase part of the dry well region and the liquid phase part (pressure suppression pool) of the pressure suppression chamber with a plurality of vent pipes.

In a wet type reactor containment vessel, water vapor released into the dry well area when a LOCA occurs is transferred to the pressure suppression pool in the pressure suppression chamber via a vent pipe using the pressure difference between the dry well area and the pressure suppression chamber as a driving force. Inflow. A wet reactor containment vessel can efficiently suppress a rise in pressure within the reactor containment vessel by condensing water vapor with pool water filled in a pressure suppression pool.

Additionally, in the unlikely event that LOCA continues, water vapor will flow out of the reactor pressure vessel, causing the water level inside the reactor pressure vessel to drop, but the water level can be restored by water injection from the emergency core cooling system. Therefore, damage to the core can be prevented.
In addition, as water vapor 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 increase, but residual heat from the emergency core cooling system By removing heat from the pressure suppression pool water using the removal system, the temperature of the pressure suppression pool water and the pressure within the reactor containment vessel can be reduced, and as a result, overpressure damage to the reactor containment vessel can be prevented.

However, although it is an extremely rare event, it is conceivable that all the emergency core cooling systems will lose their functionality when a LOCA occurs. Even if such an accident that exceeds the design basis (non-design basis accident) occurs, current BWRs are equipped with equipment to deal with serious accidents in order to prevent the accident from progressing to a serious accident (an accident involving core damage). By injecting water into the reactor core using a low-pressure alternative water injection system (reactor water injection) and by taking measures to prevent overpressure damage to the containment vessel using a containment vessel pressure relief device (filter vent device), damage to the reactor core and overflow of the reactor containment vessel can be prevented. 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 source is required as a power source, but as in Patent Document 2, reactor water injection can be achieved simply by controlling a valve that can be operated using a DC power source (battery). , measures to prevent damage to the reactor core are also known.

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

According to the technology described in Patent Document 1, the gas inside the reactor containment vessel is discharged to the outside of the reactor containment vessel through a filter vent device having a function of removing radioactive substances, thereby removing the radioactive substances from the environment. It is possible to prevent overpressure damage to the reactor containment vessel while greatly suppressing the amount released to the reactor. However, the technology described in Patent Document 1 does not have a water injection function to the reactor pressure vessel, and in order to prevent damage to the reactor core, it is necessary to use static water injection equipment such as the technology described in Patent Document 2 mentioned above. It is necessary to separately add water injection equipment to the reactor pressure vessel.

On the other hand, according to the technology described in the above-mentioned Patent Document 2, by using static equipment that does not require an AC power source, water injection into the reactor can be achieved simply by controlling valves that can be operated using a DC power source (battery), thereby causing damage to the reactor core. can be prevented. However, the technology described in Patent Document 2 does not have a function to prevent overpressure damage to the reactor containment vessel, and in order to prevent overpressure damage to the reactor containment vessel, the technology described in Patent Document 1 described above cannot be used. It is necessary to separately add overpressure damage prevention equipment for the reactor containment vessel.

The present invention has been made in view of the above-mentioned background, and although it has a simple configuration, even if the emergency core cooling system loses its function, it will not cause damage to the reactor core or overpressure damage to the reactor containment vessel in the event of a LOCA. The main objective is to provide an overpressure protection device for reactor containment vessels that prevents The purpose of solving other problems will be explained as appropriate in the detailed description.

In order to achieve the above object, the present invention provides an overpressure protection device for a reactor containment vessel, which is disposed outside a reactor containment vessel containing a reactor pressure vessel, and which is an emergency condenser that cools and condenses water vapor generated in the reactor core and returns it to water; and an emergency condenser pool that immerses the emergency condenser in water, and the emergency condenser comprises a plurality of heat exchanger tubes, an upper header that bundles the upper sides of the heat exchanger tubes, a lower header that bundles the lower sides of the heat exchanger tubes, and one end of which is located near the bottom of the emergency condenser pool. and a lower header vent pipe which is arranged and whose other end is connected to the lower header, and which is arranged on the path of the lower header vent pipe, and when the water level drops more than expected in the reactor pressure vessel. or a lower header vent valve that opens when pressure increases beyond expectations in the reactor containment vessel, and one end of which is located at a higher position than the lower header vent pipe inside or outside of the emergency condenser pool; and an upper header vent pipe which is arranged and whose other end is connected to the upper header, and which is arranged on the path of the upper header vent pipe, and when the water level drops more than expected in the reactor pressure vessel. Alternatively, the reactor containment vessel may be configured to include an upper header vent valve that is opened when pressure increases beyond expectations in the reactor containment vessel .
Other means will be described later.

According to the present invention, although the configuration is simple, damage to the reactor core and overpressure failure of the reactor containment vessel can be prevented in the event of a LOCA even if the emergency core cooling system loses its function.

FIG. 1 is a system diagram showing the configuration of an overpressure protection device for a reactor containment vessel according to a first embodiment. FIG. 2 is a system diagram showing the configuration of an overpressure protection device for a reactor containment vessel according to a second embodiment. FIG. 3 is a system diagram showing the configuration of an overpressure protection device for a reactor containment vessel according to a third embodiment. FIG. 3 is a system diagram showing the configuration of an overpressure protection device for a reactor containment vessel according to a fourth embodiment. It is a system system diagram showing the composition of the overpressure protection device of the nuclear reactor containment vessel concerning a 5th embodiment. It is a system system diagram showing the composition of the overpressure protection device of the nuclear reactor containment vessel concerning a 6th embodiment. FIG. 7 is a system diagram showing the configuration of an overpressure protection device for a reactor containment vessel according to a seventh embodiment. It is a system system diagram showing the composition of the overpressure protection device of the nuclear reactor containment vessel concerning an 8th embodiment. It is a system system diagram showing the composition of the modification of the overpressure protection device of the nuclear reactor containment vessel concerning a 1st embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail below with reference to the drawings. The figures are only shown schematically to provide a thorough understanding of the invention. Therefore, the present invention is not limited to the illustrated example. Further, in each figure, common or similar components are denoted by the same reference numerals, and redundant explanation thereof will be omitted.

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

As shown in FIG. 1, a reactor pressure vessel (RPV) 1 (RPV) containing a reactor 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 can be contained in the event of an accident.

An isolation condenser 5 (IC) is installed outside the reactor containment vessel 4 and inside the reactor building 10. The emergency condenser 5 includes a plurality of heat transfer tubes 15 that are used to cool and condense water vapor generated in the reactor core 2 and return it to water, which are bundled together using two upper and lower headers (an upper header 14 and a lower header 16). It is something that

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

The overpressure protection device 100 is disposed outside the reactor containment vessel 4 that includes the reactor pressure vessel 1, and cools and condenses water vapor generated in the reactor core included in the reactor pressure vessel 1, and converts it into water. It includes an emergency condenser 5 for returning the water, and an emergency condenser pool 9 for immersing the emergency condenser 5 in water. The emergency condenser 5 includes a plurality of heat exchanger tubes 15, an upper header 14 that bundles the upper sides of the heat exchanger tubes 15, a lower header 16 that bundles the lower sides of the heat exchanger tubes 15, and one end of which is connected to the emergency condenser. A lower header vent pipe 17a is arranged near the bottom of the water pool 9 and the other end is connected to the lower header 16, and a lower header vent pipe 17a is arranged on the path of the lower header vent pipe 17a, and the reactor pressure It has a lower header vent valve 18a that is opened when the water level in the vessel 1 drops more than expected or when the pressure in the reactor containment vessel 4 increases more than expected.

On the route of the condensate return pipe 7, there is an emergency condenser start valve that is closed during normal operation and opens when it is necessary to remove heat from the core 2 during abnormal transients during operation or in the event of an accident. 8 (IC start valve) is installed.

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

The emergency condenser pool 9 is installed so that the bottom thereof is higher than the water level 3 inside the reactor pressure vessel 1 (RPV water level). Thereby, the emergency condenser pool 9 can send pool water into the reactor pressure vessel 1 when a loss of coolant accident (LOCA) occurs.

The route of the lower header vent pipe 17a is closed during normal operation, during abnormal transients during operation, and in the event of a design basis accident. An open lower header vent valve 18a is provided.

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, but is usually conservatively designed to ensure a certain degree of airtightness.

The operation of the overpressure protection device 100 according to the present embodiment when a LOCA occurs due to a break in the main steam pipe 20 will be described below. The following explanation deals with accidents exceeding design basis accidents (non-design basis accidents) in which the emergency core cooling system cannot be used.

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

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 also designed to open automatically when the power is lost. Because of the design, the equipment has extremely high startup reliability.

Therefore, the following description will be made on the assumption that the emergency condenser 5 can be successfully started even in the event of an accident outside the design standards. When a LOCA occurs, water vapor inside the reactor pressure vessel 1 flows into the reactor containment vessel 4, and the water level 3 (RPV water level) inside the reactor pressure vessel 1 decreases, causing the emergency condenser to start. Valve 8 opens and emergency condenser 5 starts up.

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 intake pipe 6 is opened. The water vapor inside the reactor pressure vessel 1 is drawn into the emergency condenser 5 through the IC, and the drawn water vapor is condensed by the cooling water of the emergency condenser pool 9 in the heat transfer tube 15, thereby generating water in the reactor core 2. The decay heat that occurs can be discharged to the outside of the reactor containment vessel 4 (to the cooling water of the emergency condenser pool 9).

However, although the emergency condenser 5 can condense water vapor in the reactor pressure vessel 1, it cannot inject water into the reactor pressure vessel 1 from a water source (water pool, etc.) outside the reactor containment vessel 4. It cannot be done.

As the LOCA continues, the cooling water (steam) inside the reactor pressure vessel 1 continues to flow into the reactor containment vessel 4 through the rupture port, so even after the emergency condenser 5 starts up, the nuclear The water level 3 (RPV water level) inside the reactor pressure vessel 1 continues to gradually decrease.

The pressure in the reactor pressure vessel 1 and the reactor containment vessel 4 is determined by the fact that the emergency condenser 5 can remove heat from the reactor core 2, that is, heat can be removed from the inside of the reactor pressure vessel 1 and the reactor containment vessel 4. Although it depends on the heat removal capacity of the emergency condenser 5, the rate of pressure rise in 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 condenser 5 decreases. There is a possibility that the pressure in the pressure vessel 1 and the reactor containment vessel 4 will continue to rise.

If such a situation continues, the reactor core 2 will be exposed above the water surface, causing damage to the reactor core 2, and the pressure inside the reactor containment vessel 4 will continue to rise, causing the reactor containment vessel to collapse. There is a possibility that the container 4 will be damaged due to overpressure.

Therefore, the overpressure protection device 100 according to the present embodiment automatically starts the emergency condenser start valve 8 based on a high pressure signal inside the reactor pressure vessel 1, a low water level signal inside the reactor pressure vessel 1, etc. Or, in addition to the function of the current emergency condenser, which opens manually, when the water level 3 inside the reactor pressure vessel 1 (RPV water level) becomes extremely low and there is a possibility that the reactor core 2 may be exposed. Or, when the pressure inside the reactor containment vessel 4 becomes extremely high and there is a possibility that the reactor containment vessel 4 will be damaged due to overpressure, the lower header vent valve 18a is set to Automatic activation or manual opening by a high signal (a signal generated at a pressure higher than the high pressure signal) or a low/low water level signal inside the reactor pressure vessel 1 (a signal generated at a water level lower than the low water level signal) do.

In other words, the overpressure protection device 100 protects the emergency condenser pool 9 (IC pool) from cooling water (pool water) when a loss of coolant 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 with the following:

Immediately after the lower header vent valve 18a is opened, the lower header vent pipe 17a is used for gas discharge to discharge water vapor containing radioactive materials in the reactor pressure vessel 1 into the cooling water (pool water) of the emergency condenser pool 9. Functions as a line. Then, after a while after the opening of the lower header vent valve 18a, the lower header vent pipe 17a becomes a cooling water supply line that supplies the cooling water (pool water) of the emergency condenser pool 9 to the reactor containment vessel 4. Function. This point will be explained in detail below.

Immediately after the lower header vent valve 18a is opened, 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. be discharged. Therefore, at the initial stage of LOCA occurrence, the lower header vent pipe 17a functions as a gas discharge line that discharges 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) in 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. Note that a part of the gas discharged into the emergency condenser pool 9 is guided to the stack 13 along the gas exhaust line 11, and is discharged to the atmosphere through the stack 13. Furthermore, the reactor pressure vessel 1 and the reactor containment vessel 4 are degassed and their internal pressures are reduced.

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 containment vessel spatially connected via the LOCA rupture port are 4 internal pressure decreases. At this time, due to the pressure difference between the pressure in the reactor pressure vessel 1 and the lower header vent pipe 17a that opens into the water in the emergency condenser pool 9, the cooling water (pool water) in the emergency condenser pool 9 flows into the lower part of the emergency condenser pool 9. It flows into the header vent pipe 17a and is sent from the emergency condenser 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 LOCA occurs, the lower header vent pipe 17a functions as a cooling water supply line that supplies cooling water (pool water) from 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 containment vessel 4 which is spatially connected to the reactor pressure vessel 1 through the break in the main steam pipe 20. Hereinafter, this function will be referred to as the "reactor containment vessel vent function." With this reactor containment vessel vent function, the overpressure protection device 100 can prevent overpressure damage to the reactor containment vessel 4.

When the pressure inside the reactor pressure vessel 1 is sufficiently reduced by the water vapor inside the reactor pressure vessel 1 flowing out into the cooling water of the emergency condenser pool 9, the emergency condensate is released from the lower header vent pipe 17a. The flow rate of steam discharged to the reactor 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 reactor core 2 from being exposed above the water surface. can prevent damage from occurring.

The water vapor discharged from the reactor pressure vessel 1 into the cooling water of the emergency condenser pool 9 contains some radioactive materials such as radioactive reactor internal structures (Co60, etc.) and tritiated water. Due to the effect of incorporating radioactive materials into the cooling water of the emergency condenser pool 9 (scrubbing effect), almost the entire amount of radioactive materials is retained in the cooling water of the emergency condenser pool 9.

Even a small amount of radioactive material discharged into the reactor building 10 is 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 promotes the diffusion of the exhausted gas and can significantly suppress increases in local exposure.

In this type of conventional technology, the reactor containment vessel 4 is used to confine radioactive materials in the event of an accident, and even in the event of an accident outside the design standards, water vapor containing radioactive materials is not allowed to enter the reactor building 10. Means for intentional discharge were not considered.

On the other hand, the overpressure protection device 100 according to the present embodiment prevents radioactive noble gases and fission products from occurring in the reactor pressure vessel 1 or the reactor containment vessel 4 before damage to the reactor core 2 occurs. Before release, the reactor containment vessel is vented to the reactor building 10 with some degree of airtightness. As a result, the overpressure protection device 100 according to the present embodiment prevents damage to the reactor core 2 and overpressure failure of the reactor containment vessel 4 in exchange for releasing a small amount of radioactive material, and prevents radioactive noble gas and fission products from being damaged. It is possible to eliminate the possibility that the fuel will be released outside the reactor containment vessel 4. The overpressure protection device 100 according to this embodiment can rationally reduce the amount of radioactive substances released to the outside of the reactor building 10 when an accident outside the design standards occurs.

Note that by accumulating the water vapor containing radioactive substances discharged from the lower header vent pipe 17a in another airtight closed space (such as a tank), the release of radioactive substances to the outside of the reactor building 10 can be prevented. It is also possible to consider equipment configurations to prevent this. However, the equipment configuration is more complicated than in this embodiment, and problems occur due to human error, such as overpressure damage to the tank or reactor containment vessel 4 due to incorrect closing of the tank's emergency gas discharge line, etc. There are concerns.

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

As described above, according to the overpressure protection device 100 according to the present embodiment, even in the event of a LOCA occurrence and a failure of all units of the emergency core cooling system (an accident outside of design standards), the water vapor inside the reactor pressure vessel 1 can be By discharging into the cooling water of the condenser pool 9, the amount of radioactive materials released is suppressed, and the pressure inside the reactor pressure vessel 1 and the reactor containment vessel 4 is reduced to prevent overheating of the reactor containment vessel 4. In addition to being able to prevent pressure damage, by injecting cooling water from the emergency condenser pool 9 into the reactor pressure vessel 1, exposure of the reactor core 2 to the water surface can be prevented and damage to the reactor core 2 can be prevented.
Due to the above two effects, the overpressure protection device 100 according to the present embodiment can prevent damage to the reactor core 2 and overpressure damage to the reactor containment vessel 4 with a simple configuration.

In the present embodiment, the effect of suppressing the pressure inside the reactor containment vessel 4 has been described with reference to LOCA caused by a rupture of the main steam pipe 20. However, the same effect can be obtained even when other pipes (water supply pipes, etc.) connected to the reactor pressure vessel 1 break.

Moreover, in this embodiment, the explanation was given using the vertical emergency condenser 5 in which the upper header 14, the heat exchanger tubes 15, and the lower header 16 are vertically connected. However, similar effects can be obtained with the horizontal emergency condenser 5 using U-shaped heat exchanger tubes.

[Second embodiment]
The configuration of the overpressure protection device 100A according to the second embodiment will be described below with reference to FIG. 2. FIG. 2 is a system diagram showing the configuration of an 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 (see FIG. 1) according to the first embodiment 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) Dynamic load suppressors 19a and 19b are installed at the openings of the lower header vent pipe 17a and the upper header vent pipe 17b toward 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 at a higher position inside the emergency condenser pool 9 than the lower header vent pipe 17a, and The other end of the upper header vent pipe 17b is connected to the upper header 14, and the upper header vent pipe 17b is arranged on the path of the upper header vent pipe 17b, and is used when the water level in the reactor pressure vessel 1 drops more than expected or when the reactor is contained. It has an upper header vent valve 18b that is opened when the pressure inside the container 4 increases more than expected.

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

For example, at the initial stage of LOCA occurrence, 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, passes through the emergency condenser 5, and enters the lower header vent pipe. 17a and the upper header vent pipe 17b to the emergency condenser pool 9. Therefore, at the initial stage of LOCA occurrence, both the lower header vent pipe 17a and the upper header vent pipe 17b convert the gas generated in the reactor pressure vessel 1 into the cooling water (pool water) of the emergency condenser pool 9. It functions as a gas exhaust line. At this time, since the flow rate of gas 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 into the emergency condenser pool 9 mixes with the air inside the reactor building 10, and by mixing, the gas in the reactor building 10 whose amount of radioactive material per unit volume has been reduced becomes gas. It is led along the exhaust line 11 to the stack 13 and exhausted to the atmosphere through the stack 13. Furthermore, the reactor pressure vessel 1 and the reactor containment vessel 4 are degassed and their internal pressures are reduced.

After some time has passed since 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 are reduced. The lower header vent pipe 17a is arranged at a lower position (deeper water depth) than the upper header vent pipe 17b in the emergency condenser pool 9. Therefore, higher water pressure is applied to one end (opening) of the lower header vent pipe 17a than to 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 condenser pool 9 and the reactor pressure vessel 1 increases. Due to the difference, the cooling water (pool water) in the emergency condenser pool 9 flows into the lower header vent pipe 17a and flows from the emergency condenser pool 9 to the reactor via the lower header 16 and the condensed water return pipe 7. It is sent into 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 that supplies cooling water (pool water) from the emergency condenser pool 9 to the reactor pressure vessel 1. do. At this time, the upper header vent pipe 17b continues to function as a gas exhaust line.

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

After this, when further time passes after the occurrence of LOCA, the reactor pressure vessel 1 is further degassed, and the internal pressure of the reactor pressure vessel 1 is further reduced. 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 condenser pool 9 The upper header vent pipe 17b, which is located at a higher position than the lower header vent pipe 17a, also serves as a cooling water supply line that supplies cooling water (pool water) from the emergency condenser pool 9 to the reactor pressure vessel 1. functions as

In addition, in the overpressure protection device 100A according to the present embodiment, the emergency condenser 5 supplies gas in the form of bubbles to one end of the upper header vent pipe 17b and one end of the lower header vent pipe 17a. It has dynamic load suppressing devices 19a and 19b for discharging water into the water of the emergency condenser pool 9. Note that as the dynamic load suppressing devices 19a and 19b, for example, a quencher or the like that makes water vapor bubbles finer 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 structures (walls and floors) of the emergency condenser pool 9. . The structure (walls and floor) of the emergency condenser pool 9 may be damaged due to its dynamic load.
Therefore, in this embodiment, dynamic load suppressors 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 suppressors 19a and 19b atomize the gas discharged into the emergency condenser pool 9 into bubbles. Thereby, the overpressure protection device 100A suppresses the dynamic load applied to the structures (walls and floors) of the emergency condenser pool 9, and Damage inflicted can be reduced.

The overpressure protection device 100A according to this embodiment can improve the following points when 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 steam release from the reactor pressure vessel 1 and cooling water injection into the reactor pressure vessel 1 are performed through one line (lower header vent pipe 17a). However, it takes some time until the amount of water vapor discharged from the lower header vent pipe 17a is sufficiently reduced, a gas-liquid counterflow state is realized, and water injection into the reactor pressure vessel 1 is started.

In contrast, in the overpressure protection device 100A according to the present embodiment, an upper header vent pipe 17b and an upper header vent valve 18b are newly provided in a place where the water depth of the emergency condenser pool 9 is shallow. Release of water vapor inside the reactor pressure vessel 1 via the pipe 17b, and emergency release to the reactor pressure vessel 1 via the lower header vent pipe 17a installed at a deep place in the emergency condenser pool 9. It becomes possible to inject cooling water into the condenser pool 9 in parallel, and the timing to start injecting water into the reactor pressure vessel 1 can be brought forward. Thereby, the overpressure protection device 100A according to the present embodiment can improve the reliability of the function of preventing damage to the core 2.

Moreover, the overpressure protection device 100A according to the present embodiment has dynamic load suppressing devices 19a and 19b installed at the openings of the lower header vent pipe 17a and the upper header vent pipe 17b on the side of the emergency condenser pool 9. Therefore, immediately after opening the lower header vent valve 18a and the upper header vent valve 18b, a high flow rate of water vapor released from the reactor pressure vessel 1 is transferred to the emergency emergency via the lower header vent pipe 17a and the upper header vent pipe 17b. Dynamic loads applied to the structures (walls and floors) of the emergency condenser pool 9 when the cooling water is discharged into the condenser pool 9 can be suppressed. 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, compared to the first embodiment, the overpressure protection device 100A according to the present embodiment improves the reliability of the function of preventing damage to the reactor core 2 by advancing the timing of starting water injection into the reactor pressure vessel 1. , it is possible to improve the reliability of preventing damage to the emergency condenser pool 9 by suppressing the dynamic load when water vapor in the reactor pressure vessel 1 is released into the cooling water of the emergency condenser pool 9. can.

[Third embodiment]
Hereinafter, with reference to FIG. 3, the configuration of an overpressure protection device 100B according to a third embodiment will be described. FIG. 3 is a system diagram showing the configuration of an 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 (see FIG. 2) according to the second embodiment in the following points.
(1) The opening of the upper header vent pipe 17b on the side of the emergency condenser pool 9 is opened 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 lower header 16 are deleted.
(3) A collection filter 12 is installed on the gas exhaust line 11 to collect (remove) particulate radioactive substances.

In the overpressure protection device 100B according to this 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 does not flow from the upper header vent pipe 17b to the reactor building 10. It is possible to reduce the influence of dynamic loads during discharge. Therefore, the overpressure protection device 100B can reduce damage to the structures (walls and floors) of the emergency condenser pool 9.

In addition, in the overpressure protection device 100B according to the present embodiment, the overpressure protection device 100B is configured to collect particulate radioactive materials on a path for discharging gas generated in the reactor pressure vessel 1 to the atmosphere. A 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 when 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, water vapor in the reactor pressure vessel 1 flows through the lower header vent pipe 17a and the upper header vent pipe 17b. 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 preventing damage to the emergency condenser pool 9 by installing dynamic load suppressing devices 19a and 19b at the tip of each pipe. ing.

In contrast, 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 in the emergency condenser pool 9, is dominant. , the magnitude of the dynamic load that occurs when water vapor is released into the cooling water of the emergency condenser pool 9 is significantly suppressed. Therefore, the overpressure protection device 100B according to this embodiment eliminates the need for the dynamic load suppressing devices 19a and 19b at the tips of the respective pipes, and can simplify the equipment configuration.

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

As described above, when compared with the overpressure protection device 100A according to the second embodiment (see FIG. 2), the overpressure protection device 100B according to the present embodiment requires the addition of the collection filter 12, but the atomic By directly discharging the water vapor in 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, with reference to FIG. 4, the configuration of an overpressure protection device 100C according to a fourth embodiment will be described. FIG. 4 is a system diagram showing the configuration of an 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 is installed on the gas exhaust line 11 to remove particulate radioactive substances.
(2) A cooling water supply means 40 is provided as a facility for supplying cooling water to the emergency condenser pool 9.

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

In addition, in the overpressure protection device 100C according to the present embodiment, the cooling water replenishment means 40 includes a makeup water pool 21 that stores cooling water to be supplied to the emergency condenser pool 9, and a makeup water pool 21 that stores cooling water to be supplied to the emergency condenser pool 9. A makeup water pipe 23 that connects the water pool 21 and a makeup water pipe 23 that is arranged on the route of the makeup water pipe 23 and prevents the backflow of cooling water from the makeup water pool 21 to the emergency condenser pool 9 to the makeup water pool 21. It has a make-up water pipe check valve 24 that prevents.

The bottom surface of the make-up water pool 21 is located 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, the overpressure protection device 100C reduces the water head between the cooling water in the emergency condenser pool 9 and the makeup water in the makeup water pool 21 when the cooling water in the emergency condenser pool 9 decreases when a LOCA occurs. Water flows from the make-up water pool 21 to the emergency condenser pool 9 due to the pressure difference.

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.

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

The overpressure protection device 100C according to the present embodiment can improve the following points when 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, although it depends on the amount of water stored in the emergency condenser pool 9, the cooling water (pool water) of the emergency condenser pool 9 is supplied to the lower header vent pipe 17a. By injecting water into the reactor pressure vessel 1 through the water, the amount of water in the emergency condenser pool 9 may decrease, and the emergency condenser 5 and upper header vent pipe 17b may be exposed above the water surface. . If the upper header vent pipe 17b is exposed above the water surface, the scrubbing effect of the cooling water from the emergency condenser pool 9 cannot be expected, and although the amount is small, radioactive materials inside the reactor pressure vessel 1 will be transferred to the reactor building 10. There is a possibility of direct release into the internal space of the Although it is possible to avoid such a situation by replenishing cooling water to the emergency condenser pool 9 using a fire engine, etc., in the event of an accident outside the design standards, accessibility to the reactor building 10 will deteriorate. This may make it difficult for fire engines to replenish cooling water.

In contrast, in the overpressure protection device 100C according to the present embodiment, when the water level of the emergency condenser pool 9 decreases, the water depth difference (head pressure difference) between the emergency condenser pool 9 and the make-up water pool 21 is reduced. As driving force, cooling water from the make-up water pool 21 is automatically supplied to the emergency condenser pool 9 via the make-up water pipe 23. Thereby, the overpressure protection device 100C according to the present embodiment prevents the upper header vent pipe 17b from being exposed above the water surface, and maintains the scrubbing effect of radioactive materials by the cooling water of the emergency condenser pool 9. Can be done.

Moreover, the overpressure protection device 100C according to the present embodiment arranges the make-up water pool 21 outside the reactor building 10 with good accessibility, so that cooling water can be supplied to the make-up water pool 21 by a fire engine or the like. Since it is easy to use, it is possible to stably obtain the scrubbing effect of radioactive substances for a long period of time.

In addition, the overpressure protection device 100C according to the present embodiment includes a makeup water pipe check valve 24 on the route of the makeup water pipe 23, so that the cooling water of the emergency condenser pool 9 containing a small amount of radioactive material can be replenished. It is possible to prevent the water from flowing out to the water pool 21 side.

Moreover, since the overpressure protection device 100C according to the present embodiment maintains the scrubbing effect, almost all of the small amount of radioactive material released from the reactor pressure vessel 1 is retained in the cooling water of the emergency condenser pool 9. However, the radioactive substances released into the reactor building 10 that cannot be completely removed by the scrubbing effect are collected by the collection filter 12 before being discharged from the stack 13 via the gas exhaust line 11. (Remove. Thereby, the overpressure protection device 100C according to the present embodiment can further reduce the amount of radioactive material released to the outside of the reactor building 10 than the overpressure protection device 100A according to the second embodiment.

As described above, compared to the second embodiment, the overpressure protection device 100C according to the present embodiment is equipped with the make-up water pool 21 outside the reactor building 10, which allows easy replenishment of cooling water. Since the water level of the water tank pool 9 can be maintained higher than the upper header vent pipe 17b, the scrubbing effect of radioactive materials by the cooling water of the emergency condenser pool 9 can be continuously obtained, and the radioactive substances can be removed by the scrubbing effect. Since the particulate radioactive substances that cannot 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. .

Note that the makeup water pool 21 can also be installed inside the reactor building 10. In this case, the makeup water pipe check valve 24 becomes unnecessary.

[Fifth embodiment]
Hereinafter, with reference to FIG. 5, the configuration of an overpressure protection device 100D according to a fifth embodiment will be described. FIG. 5 is a system diagram showing the configuration of an 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 more effective in cooling the emergency condenser pool 9 than the overpressure protection device 100C according to the fourth embodiment (see FIG. 4). The difference is that a cooling water replenishing means 40D is provided as a water replenishing facility instead of the cooling water replenishing means 40.

The cooling water supply means 40D includes a makeup water pool 21 that stores cooling water to be supplied to the emergency condenser pool 9, a makeup water pipe 23 that connects the emergency condenser pool 9 and the makeup water pool 21, and a makeup water pipe. 23, and pumps up cooling water from the makeup water pool 21 and sends it to the emergency condenser pool 9, overcoming the gravity difference.

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

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

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

Note that the make-up water pump 22 may be a permanently installed pump, or may be a portable pump such as a fire engine.

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

As shown in FIG. 6, the overpressure protection device 100E according to the sixth embodiment differs from the overpressure protection device 100A (see FIG. 2) according to the second embodiment in the following points.
(1) A membrane filter (rare gas filter 25) that blocks radioactive rare gas and transmits water vapor is installed at 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-free equipment for recombining hydrogen and oxygen to prevent a hydrogen explosion.

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

The overpressure protection device 100E includes a rare gas filter 25. The rare gas filter 25 blocks radioactive rare gas and transmits water vapor. Thereby, 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, etc. can be used. These membranes have the property of allowing gases with small molecular diameters such as hydrogen and water vapor to pass through, but not allowing gases with large molecular diameters such as xenon (Xe) to pass through. Note that the overpressure protection device 100E may have a configuration including a collection filter 12 on the gas exhaust line 11 in addition to the rare gas filter 25, as shown in FIG.

Further, the overpressure protection device 100E according to the present embodiment is arranged in the reactor building 10 that includes the reactor containment vessel 4, and is a static catalytic hydrogen regeneration device 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 combine hydrogen and oxygen through the action of a catalyst.

The overpressure protection device 100E according to the present embodiment can improve the following points when 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 reactor core 2 can be prevented by injecting cooling water from the emergency condenser pool 9 into the reactor pressure vessel 1 via the lower header vent pipe 17a. It is. However, if damage to the reactor core 2 occurs due to a delay in depressurizing the reactor pressure vessel 1 or injecting cooling water into the emergency condenser pool 9, the fuel rods loaded in the reactor core 2 will be trapped inside. Volatile fission products (such as Cs) and radioactive noble gases (such as Due to the chemical reaction, hydrogen gas is generated inside the reactor pressure vessel 1.

When these gases are released into the cooling water of the emergency condenser pool 9 through the upper header vent pipe 17b, almost all volatile fission products such as Cs are removed from the emergency condenser pool 9 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 into 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, and is then recombined with oxygen contained in the air inside the reactor building 10. Return to Thereby, the overpressure protection device 100E according to this embodiment can prevent a hydrogen explosion from occurring in the reactor building 10.

Moreover, the overpressure protection device 100E according to the present embodiment is designed to prevent overpressure damage to the reactor building 10 and gas leakage from the reactor building 10 while retaining the radioactive noble gas inside the reactor building 10. , a rare gas filter 25 is installed. The overpressure protection device 100E according to the present embodiment is configured to remove hydrogen that cannot be completely processed by the static catalytic hydrogen recombination device 26 and the emergency condenser, which causes pressurization inside the reactor building 10. Water vapor and the like evaporated from the pool 9 can be selectively discharged from the reactor building 10 while radioactive rare gases (such as Xe) can be retained inside the reactor building 10.

As described above, the overpressure protection device 100E according to the present embodiment is more effective than the overpressure protection device 100A according to the second embodiment (see FIG. 2) in the event that damage to the core 2 occurs and volatilization Even if a situation occurs in which radioactive substances, radioactive rare gases, hydrogen, etc. are released into the reactor building 10 via the emergency condenser pool 9, the volatile nature of the cooling water in the emergency condenser pool 9 The effect of scrubbing radioactive substances, the effect of removing hydrogen by the static catalytic hydrogen recombination device 26, and the effect of confining radioactive rare gas in the reactor building 10 by the rare gas filter 25 can be obtained. Therefore, the overpressure protection device 100E according to the present embodiment can reduce the possibility of a hydrogen explosion occurring inside the reactor building 10 and reduce the amount of radioactive material released to the outside of the reactor building 10. .

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

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

In the overpressure protection device 100F according to this embodiment, the emergency condenser pool 9a is an airtight closed space, and inside the reactor pressure vessel 1 in the emergency condenser pool 9a. A gas exhaust line 11 is provided for exhausting the generated gas to the atmosphere.

In addition, in the overpressure protection device 100F according to the present embodiment, the emergency condenser pool 9a is a closed space with airtightness, and the emergency condenser pool 9a is an airtight closed space, and the emergency condenser pool 9a is discharged from the reactor pressure vessel 1 to the emergency condenser pool 9a. It is possible to confine water vapor containing some radioactive material in a closed space. Therefore, release of radioactive substances to the outside can be completely prevented. However, in the unlikely event that the reactor core is damaged, a large amount of gas containing hydrogen will be discharged from the reactor pressure vessel 1 into the emergency condenser pool 9a, and there is a risk that the emergency condenser pool 9a will be damaged by overpressure. In this case, 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.

Note that the emergency condenser pool 9a may be placed inside the reactor building 10 or outside the reactor building 10. In other words, the reactor building 10 may be configured so that the emergency condenser pool 9a is disposed inside, as shown by the dashed-dotted line, or the emergency condenser pool 9a is disposed outside, as shown by the dashed-double line. It may be configured such that a water container pool 9a is arranged.

The overpressure protection device 100F according to this embodiment can improve the following points when 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 into the reactor building 10, and only a small amount of the radioactive material is The gas is discharged from the stack 13 to the outside of the reactor building 10 via a 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 small amount of radioactive material can be removed from the gas phase of the emergency condenser pool 9a. You can save up to 30. The overpressure protection device 100F according to this embodiment can almost completely prevent radioactive materials from being discharged to the outside of the reactor building 10.

As described above, the overpressure protection device 100F according to the present embodiment prevents overpressure damage to the emergency condenser pool 9a by ensuring a sufficient space volume of the gas phase section 30 of the emergency condenser pool 9a. can be prevented. The overpressure protection device 100F according to the present embodiment has the possibility that the pressure in the gas phase section 30 of the emergency condenser pool 9a increases beyond the maximum working pressure of the emergency condenser pool 9a. When the emergency vent valve 27 is opened, the gas in the gas phase part 30 of the emergency condenser pool 9a can be 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 overpressure damage to the emergency condenser pool 9a in the unlikely event that the emergency condenser pool 9a is damaged.

Furthermore, by opening the lower header vent pipe 17a and the upper header vent pipe 17b into another airtight tank instead of the emergency condenser pool 9a, the discharge of radioactive materials to the outside of the reactor building 10 can be prevented. can be completely prevented. However, the overpressure protection device 100F according to this embodiment can achieve the same effect with a simpler configuration than such a configuration.

As described above, compared to the second embodiment, the overpressure protection device 100F according to the present embodiment stores even a very small amount of radioactive material in the gas phase portion 30 of the emergency condenser pool 9a, thereby reducing the atomic The discharge of radioactive substances to the outside of the furnace building 10 can be almost completely prevented.

In addition, the overpressure protection device 100F according to the present embodiment has a possibility that the pressure in the gas phase section 30 of the emergency condenser pool 9a increases beyond the maximum working pressure of the emergency condenser pool 9a. If there is, the gas in the gas phase part 30 of the emergency condenser pool 9a can be discharged to the outside of the reactor building 10 via the gas exhaust line 11 and the stack 13 by opening the emergency vent valve 27. You can also do it.

[Eighth embodiment]
Hereinafter, with reference to FIG. 8, the configuration of an overpressure protection device 100G according to the eighth embodiment will be described. FIG. 8 is a system diagram showing the configuration of an 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 different from the overpressure protection device 100F according to the seventh embodiment (see FIG. 7) in that the overpressure protection device 100G according to the eighth embodiment The difference is that the gas phase part 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 part 30 of the emergency condenser pool 9a and the reactor containment vessel 4, and also connects the gas phase part 30 of the emergency condenser pool 9a. A gas return line 28 for returning the gas to the reactor containment vessel 4, and a gas return valve 29 disposed on the path of the gas return line 28 and opening and closing the gas return line.

The overpressure protection device 100G according to this 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 can, for example, install dynamic heat removal equipment for the reactor containment vessel 4 after a sufficient period of time has elapsed since the occurrence of an out-of-design standard accident. (Heat removal equipment using pumps and heat exchangers) is restored and the pressure in the reactor containment vessel 4 is reduced, by opening the gas return valve 29, the gas phase in the emergency condenser pool 9a is removed. The gas containing a small amount of radioactive material accumulated in the section 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 to the emergency condenser pool 9a.

In other words, if the accident were to last for a long time, there is a possibility that the heat removal equipment for cooling the reactor containment vessel 4 would be restored. Then, when the heat removal equipment is restored, the overpressure protection device 100G does not need to open the emergency vent valve 27. Such an overpressure protection device 100G can reduce the amount of gas released into the atmosphere and, by extension, the amount of radioactive substances.

The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. It is possible to replace a part of the configuration of the embodiment with other configurations, and it is also possible to add other configurations to the configuration of the embodiment. Furthermore, it is possible to add, delete, or replace a part of each configuration with other configurations.

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

In the above-described first embodiment, the pressure in the reactor containment vessel 4 is suppressed by the overpressure protection device 100 on the assumption that a LOCA occurs and the emergency core cooling system is inoperable as an accident outside the design standards of a boiling water reactor. The effect was explained. However, the overpressure protection device 100 can obtain similar effects even in the event of an accident outside the design standards of other types of boiling water light water reactors having different safety system configurations.

For example, as shown in FIG. 9, the overpressure protection device 100 is installed in place of the emergency core cooling system, closer to the reactor pressure vessel 1 than the LOCA rupture port, and as close to the reactor pressure vessel 1 as possible. Similar effects can be obtained even when applied to a boiling water type light water reactor (reactor pressure vessel isolation type plant) provided with the RPV isolation valve 31 directly attached to the reactor pressure vessel 1.

If a LOCA, which is a design basis accident, occurs in a reactor pressure vessel isolation type plant with such a configuration, first, by closing the RPV isolation valve 31, water vapor in the reactor pressure vessel 1 will be released from the LOCA rupture port. Preventing it from flowing into the reactor containment vessel 4. When the RPV isolation valve 31 is closed, the reactor pressure vessel 1 becomes isolated, so the pressure inside the reactor pressure vessel 1 increases due to the water vapor generated in the reactor core 2, and the water level 3 inside the reactor pressure vessel 1 ( RPV water level) decreases. Therefore, the overpressure protection device 100 activates the emergency condenser 5 using a high pressure signal inside the reactor pressure vessel 1 or a low water level signal inside the reactor pressure vessel 1 as a trigger, and The water vapor inside 1 is condensed and returned to water. Thereby, the overpressure protection device 100 suppresses an increase in pressure inside the reactor pressure vessel 1 and prevents damage to the reactor core 2 by returning condensed water to the reactor pressure vessel 1.

Furthermore, if an accident outside the design standards occurs in a reactor pressure vessel isolated plant, that is, if the RPV isolation valve 31 fails to close, the situation will be the same as failure to start the emergency core cooling system. That is, in this case, water vapor continues to flow from the LOCA rupture port from the reactor pressure vessel 1 to the reactor containment vessel 4, and as the pressure inside the reactor containment vessel 4 increases, the pressure inside the reactor pressure vessel 1 increases. The situation is such that the internal water level 3 (RPV water level) continues to decrease. Therefore, even in the case of a reactor pressure vessel isolated type plant, the overpressure protection device 100 is used to prevent damage to the reactor core 2 and overpressure failure of the reactor containment vessel 4, as in a boiling water light water reactor having an emergency core cooling system. Prevention can be achieved.

1: Reactor pressure vessel (RPV)
2: Core 3: Water level (RPV water level)
4: Reactor containment vessel (PCV)
5: Emergency condenser (IC)
6: Steam intake pipe 7: Condensed water return pipe 8: Emergency condenser starting valve (IC starting 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 suppressor 20: Main steam pipe 21 : Makeup water pool 22 : Makeup water pump 23 : Makeup water pipe 24 : Makeup 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 section 31: RPV isolation valve 40, 40D: Cooling water supply means 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G: Overpressure protection device

Claims (11)

an emergency condenser that is disposed outside a reactor containment vessel that includes a reactor pressure vessel, and that cools and condenses water vapor generated in the reactor core that is included in the reactor pressure vessel and returns it to water;
an emergency condenser pool for immersing the emergency condenser in water,
The emergency condenser is
multiple heat exchanger tubes,
an upper header that bundles the upper sides of the heat exchanger tubes;
a lower header that bundles the lower sides of the heat exchanger tubes;
a lower header vent pipe having one end disposed near the bottom within the emergency condenser pool and the other end connected to the lower header;
a lower header vent valve that is disposed on the path of the lower header vent pipe and is opened 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 upper header vent pipe, one end of which is located at a higher position than the lower header vent pipe inside or outside of the emergency condenser pool, and the other end of which is connected to the upper header;
an upper header vent valve that is disposed on the path of the upper header vent pipe and is opened 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 nuclear reactor containment vessel, characterized by having the following. The overpressure protection device for a reactor containment vessel according to claim 1 ,
The emergency condenser bubbles gas generated within the reactor pressure vessel into one end of the upper header vent pipe and one end of the lower header vent pipe. An overpressure protection device for a reactor containment vessel, characterized by having a dynamic load suppression device that discharges water into the water of a condenser pool. The overpressure protection device for a reactor containment vessel according to claim 1 ,
An overpressure protection device for a reactor containment vessel, wherein one end of the upper header vent pipe is opened at a position above the water surface of the emergency condenser pool. The overpressure protection device for a reactor containment vessel according to any one of claims 1 to 3 ,
The overpressure protection for the reactor containment vessel is further provided with a collection filter for collecting particulate radioactive materials on a path for discharging gas generated in the reactor pressure vessel to the atmosphere. Device. In the overpressure protection device for a reactor containment vessel according to any one of claims 1 to 4 ,
An overpressure protection device for a reactor containment vessel, further comprising a cooling water supply means for supplying cooling water to the emergency condenser pool. In the overpressure protection device for a reactor containment vessel according to claim 5 ,
The cooling water supply means includes:
a makeup water pool that stores cooling water to be replenished to the emergency condenser pool;
a makeup water pipe connecting the emergency condenser pool and the makeup water pool;
Overpressure in a reactor containment vessel, comprising: a make-up water pipe check valve that is disposed on the route of the make-up water pipe and prevents backflow of cooling water to be replenished to the emergency condenser pool. Protective device. In the overpressure protection device for a reactor containment vessel according to claim 5 ,
The cooling water supply means includes:
a makeup water pool that stores cooling water to be replenished to the emergency condenser pool;
a makeup water pipe connecting the emergency condenser pool and the makeup water pool;
Overpressure in a nuclear reactor containment vessel, comprising a make-up water pump disposed on the route of the make-up water pipe and pumping up cooling water from the make-up water pool and sending it to the emergency condenser pool. Protective device. The overpressure protection device for a reactor containment vessel according to any one of claims 1 to 7 ,
Furthermore, the overpressure of the reactor containment vessel is characterized in that a rare gas filter that blocks radioactive rare gases and transmits water vapor is provided on a path for discharging gas generated in the reactor pressure vessel to the atmosphere. Protective device. The overpressure protection device for a reactor containment vessel according to any one of claims 1 to 8 ,
A reactor containment vessel overflow system, characterized in that it is provided with a static catalytic hydrogen recombination device disposed in a reactor building containing the reactor containment vessel and for recombining hydrogen and oxygen. Pressure protection device. The overpressure protection device for a reactor containment vessel according to any one of claims 1 to 8 ,
The emergency condenser pool is an airtight closed space, and includes a gas exhaust for discharging gas generated in the reactor pressure vessel in the emergency condenser pool to the atmosphere. 1. An overpressure protection device for a reactor containment vessel, comprising: an emergency vent valve on the gas exhaust line that opens when there is a risk of overpressure damage to an airtight closed space. an emergency condenser that is disposed outside a reactor containment vessel that includes a reactor pressure vessel, and that cools and condenses water vapor generated in the reactor core that is included in the reactor pressure vessel and returns it to water;
an emergency condenser pool for immersing the emergency condenser in water,
The emergency condenser is
multiple heat exchanger tubes,
an upper header that bundles the upper sides of the heat exchanger tubes;
a lower header that bundles the lower sides of the heat exchanger tubes;
a lower header vent pipe having one end disposed near the bottom within the emergency condenser pool and the other end connected to the lower header;
a lower header vent valve that is disposed on the path of the lower header vent pipe and is opened 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; has
The emergency condenser pool is an airtight closed space, and includes a gas exhaust for discharging gas generated in the reactor pressure vessel in the emergency condenser pool to the atmosphere. an emergency vent valve on the gas exhaust line that opens when there is a risk of overpressure damage to the airtight closed space;
a gas return line for connecting the gas phase part of the emergency condenser pool and the reactor containment vessel, and for returning gas in the gas phase part of the emergency condenser pool to the reactor containment vessel; and,
An overpressure protection device for a reactor containment vessel, comprising: a gas return valve that is disposed on a path of the gas return line and opens and closes the gas return line.

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