JP2011242184A - Anti-overpressure device for nuclear reactor containment vessel, and method for operation of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize means which suppresses the increase of pressure in a nuclear reactor containment vessel due to a severe accident, while preventing discharge of radioactive substances to the environment and reaction between a combustible gas and oxygen and taking economic efficiency into consideration, and to reduce a risk to a worker who enters an upper reactor building during normal operation.SOLUTION: A reactor building comprises a nuclear reactor containment vessel 3 and an upper reactor building 9 which is located above an ancillary building surrounding a region of the nuclear reactor containment vessel 3. An airtight space 13 is provided in an upper section of the upper reactor building 9. A wetwell 5 and the airtight space 13 are connected by a discharge conduit 14 via a rupture disk 11 which is released when a pressure in the wetwell 5 increases to approach a limit value. The airtight space 13 is connected to a vacuum pump of a vacuum exhaust system via an isolation valve 16. An operation of the vacuum exhaust system and an opening operation of the isolation valve 16 are triggered by generation of a severe accident occurrence signal, and the vacuum pump is stopped to close the isolation valve 16 before the pressure in the wetwell 5 reaches a pressure at which the rupture disk 11 is released.

Description

  The present invention relates to a reactor containment vessel overpressure prevention apparatus suitable for application to a boiling water nuclear power plant and an operating method thereof.

  A reactor building of a boiling water nuclear power plant includes a region for storing a reactor as a reactor containment vessel (hereinafter also simply referred to as a containment vessel), and an upper reactor building is constructed above the reactor containment vessel. The reactor vessel is stored in the reactor containment vessel.

  The reactor building is made of concrete, and is equipped with a concrete containment vessel that has been installed with a steel liner only on the boundary wall of the containment vessel to improve the airtightness to the environment, and the region of the containment vessel and the upper reactor building There are some which have a steel containment vessel that surrounds the whole area with a self-supporting steel vessel.

  In a boiling water nuclear power plant, the possibility of occurrence is very small, but in a severe accident that assumes multiple failures of multiple safety systems, the pressure in the containment vessel rises to the limit value due to the generation of noncondensable gas. There is a possibility of approaching. As a technology to suppress the pressure rise in the containment vessel and release of radioactive substances to the environment, the technology to release the gas phase of the containment vessel to the environment from the exhaust stack after passing through the filter and catalyst layer is the following patent Known in documents 1, 2, and 3. These techniques involve the emission of exhaust to the environment.

  On the other hand, when the containment vessel is overpressured in the event of a severe accident, the gas phase is changed from the region inside the containment vessel to the upper reactor building located above the containment vessel by opening the rupture disc (also called the rupture disk). A technique for releasing and maintaining the soundness of the containment vessel and avoiding the release of exhaust to the environment is known in Patent Document 4 below.

  Other similar techniques using a rupturable plate in a reactor building are known in the following patent documents 5, 6, and 7. Among them, Patent Document 6 discloses a gas exhaust system that discharges gas in a space pushed out by nitrogen gas into the atmosphere, but does not evacuate the space.

  In addition, the Canadian nuclear power plant has a building that is in a vacuum state (hereinafter also referred to simply as a vacuum building) separate from the reactor building, and the nuclear power plant where the accident occurred communicates with the vacuum building, Technologies that reduce pressure are available on the Internet at addresses http://www.nucleartourist.com/systems/vacuum1.htm and http://www.sciencemag.org/feature/data/energy/pdf/se107800657. pdf ".

JP-A-3-209193 Japanese Patent Laid-Open No. 3-77095 JP-A-3-77096 JP 2004-85234 A JP 2009-150846 A JP-A-8-334585 JP 2004-333357 A

http://www.nucleartourist.com/systems/vacuum1.htm http://www.sciencemag.org/feature/data/energy/pdf/se107800657.pdf

  In the overpressure prevention technology for the concrete containment vessel (hereinafter also simply referred to as the first prior art), a non-condensable gas is generated in the event of a severe accident, so the upper part of the pressure suppression pool of the pressure suppression chamber in the containment vessel region. When the wet well pressure, which is a space, rises, it is necessary to release non-condensable gas to the environment, even after the radioactive substance is removed by a filter or the like.

  Also. When the above-described overpressure prevention technology using a rupturable plate (hereinafter also simply referred to as the second prior art) is applied to a concrete building, the wall of the upper reactor building is also used to prevent leakage to the environment. It is essential to improve airtightness and pressure resistance such as providing a liner, which increases costs.

  In the second prior art described above, in which the containment vessel and the reactor building are both made of steel and combined with a rupture disk, release of radioactive material into the environment is avoided, but the volume of the upper reactor building is required to increase. In addition, non-condensable gas generated in severe accidents also includes hydrogen, which is a flammable gas, and it is necessary to have a treatment facility that suppresses hydrogen combustion when released into a space where air (oxygen) exists. It becomes.

  On the other hand, in an example in which a vacuum building is provided in addition to the reactor building, the vacuum building is a facility that can cope with events other than severe accidents, and it is necessary to always maintain a vacuum state during normal operation. This is a state in which external pressure is constantly acting on the structural wall of the vacuum building, which is not preferable in terms of structure. Furthermore, in order to install the discharge pipe directly connected to the containment vessel outside the building, a barrier against an external hazard is necessary.

  Therefore, the problem to be solved by the present invention is to release the gas phase from the wet well into the reactor building outside the containment vessel when the wet well pressure increases and approaches a limit value in the event of a severe accident in a nuclear power plant. For the overpressure prevention device that prevents release to the environment, it is possible to suppress the increase in the cost of the reactor building and to prevent the combustible gas contained in the released non-condensable gas from reacting with oxygen. .

  Such a problem is that an airtight space for absorbing the pressure in the reactor containment vessel is provided above the traveling space of the traveling crane installed in the upper reactor building of the reactor building, and the airtight space and the reactor This can be solved by using a reactor containment vessel overpressure prevention device in which the inside of the containment vessel's wet well is connected via a rupturable plate and a vacuum exhaust system is connected to the airtight space.

  The overpressure prevention device starts the exhaust operation of the gas in the airtight space by the vacuum exhaust system after an event involving the state in which the pressure of the wet well space in the reactor pressure vessel rises, and the rupture disk opens. Before being used, the vacuum exhaust system is operated and used so as to stop the exhaust of the gas in the airtight space by the vacuum exhaust equipment.

  According to the present invention, when the pressure of the wet well rises due to the generation of non-condensable gas in a severe accident and approaches the limit value, the rupturable plate is opened and the gas phase (mainly non-condensable gas) is airtight from the wet well. It is released into the space and suppresses the pressure rise in the containment vessel, but at this time, the airtight space that accepts the released gas phase is controlled to the vacuum side from the normal pressure state during normal operation of the reactor, The effect of pressure reduction is large and the required space volume is small or the design pressure of the space may be small. As a result, the cost of the building can be suppressed and the airtight space is a vacuumed space. Therefore, the oxygen concentration is controlled to be lower than the normal state, and the reaction of the combustible gas contained in the non-condensable gas released into the airtight space with oxygen is suppressed or does not occur.

It is a longitudinal cross-sectional view of the reactor building to which the 1st Example of this invention is applied. It is a longitudinal cross-sectional view of the reactor building to which the 2nd Example of this invention is applied. It is a longitudinal cross-sectional view of the reactor building to which the 3rd Example of this invention is applied. It is a graph which shows the correlation of the space volume and pressure reduction which compares the difference of the pressure reduction effect in discharge | release space at normal pressure and a vacuum. It is a logic diagram of starting and stopping of the vacuum exhaust system in each embodiment of the present invention.

  In the embodiment of the present invention, an airtight space having airtightness and pressure resistance is installed in the upper part of the upper reactor building above the wet well of the pressure containment chamber of the reactor containment vessel, and a loss-of-coolant accident occurrence signal is generated. A vacuum exhaust system for receiving and exhausting the airtight space to a vacuum is provided. When the pressure of the wet well rises and approaches the limit value, the rupture disk provided in the middle of the flow path between the wet well and the airtight space is released by the differential pressure between the wetwell and the airtight space, and the inside of the wet well And the inside of the airtight space communicate with each other, and a gas phase such as a non-condensable gas is discharged from the wet well into the airtight space. At this time, the airtight space is normally at normal pressure, and after the occurrence of the accident, the above-mentioned signal is activated to activate the evacuation system, evacuate the airtight space, and stop the evacuation before the rupturable plate is opened. Stop the vacuum exhaust system to prevent the release of non-condensable gas to the environment outside the reactor building.

The airtight space for receiving the noncondensable gas is formed by being surrounded by a structural wall so as to prevent leakage of the noncondensable gas, and has airtightness and pressure resistance. The airtightness and pressure resistance of the airtight space are as follows. That is, the airtightness means that the amount of leakage from the airtight space when there is a pressure difference between the inside and outside of the airtight space is low, and preferably the leakage is generally 0.5% / day (@ 2 kg / cm ² ). It is intended to have an airtight structure that is less than (only leaks 0.5% / day of the space volume when the pressure difference is 2 kg / cm ² ). In addition, the pressure resistance of the airtight space means that the airtight space communicates with the pressure resistant space of the containment vessel such as the pressure suppression chamber in the event of an accident, and therefore the airtight space is preferably set to the same pressure as the design pressure applied to the containment vessel It is intended to have a withstand pressure structure.

  By doing in this way, the gas phase which has the high pressure from a wet well is absorbed in airtight space at the time of the severe accident of a nuclear power plant, and the effect which suppresses the pressure rise in a containment vessel is exhibited. In addition, since the hermetic space for receiving the gas phase released from the wet well is a vacuum at this time, the effect of reducing pressure is increased, and the required space volume of the hermetic space is small or the design pressure of the space is small. Demonstrates the effect of being small. As a result, the increase in the cost of the reactor building can be suppressed, and the non-condensable gas released into the air-tight space is released when the air-tight space receives the non-condensable gas generated at the time of the accident. Since the reaction of the combustible gas contained in the gas does not occur or can be suppressed, the cost required for measures such as the pressure resistance of the airtight space and the combustion of the combustible gas can be reduced.

  The first embodiment of the present invention will be specifically described below with reference to the drawings. In the first embodiment of the present invention shown in FIG. 1, the containment vessel 3 in which the reactor vessel 1 is placed and the entire upper reactor building 9 are covered with a self-supporting steel vessel having airtightness and pressure resistance, It is the illustration which employ | adopted this invention for the steel reactor building which has constructed the concrete outer wall in the outer periphery.

  As shown in FIG. 1, a reactor containment vessel 3 (hereinafter also simply referred to as a containment vessel 3) has a reactor containment vessel internal structure 2 in which a reactor pressure vessel 1 is placed. A device installation area 6 that can be accessed during normal operation is provided above a pressure suppression chamber composed of a pressure suppression pool 4 and a wet well 5 constituting a part of the storage container 3. In the upper reactor building spatially connected to the equipment installation area 6, a fuel pool 7 and a temporary equipment storage pool 8 are installed.

  In the steel reactor building in which the upper reactor building 9, the equipment installation area 6 and the pressure suppression chamber are covered with the steel vessel 10 in this way, a rupture disk (rupture disk) is received so as to receive the pressure in the wet well 5. 11 is installed in the horizontal partition above the wet well. On the other hand, the upper reactor building 9 covered with the steel vessel 10 is partitioned by a partition wall 12 having airtightness and pressure resistance at the upper and lower portions.

  Further, the upper sealed airtight space 13 and the outlet of the rupturable plate 11 are communicated with each other by a discharge pipe 14. As an example of the partition wall 12 in this case, a steel plate may be used similarly to the steel container 10, or a steel wall may be attached to a concrete wall having sufficient strength. FIG. 1 shows an embodiment in which the partition wall 12 is a steel plate.

  In this embodiment, a partition wall 12 is horizontally installed in a space above the traveling crane provided in the upper reactor building 9, and each work in the upper reactor building in which the partition wall 12 uses the traveling crane. It will not be an obstacle. Thus, since the space above the traveling crane that is not used for the work in the upper reactor building is provided as the airtight space 13, the workability in the upper reactor building is not affected.

  In addition, an exhaust pipe 15 is connected to the airtight space 13, and the exhaust pipe 15 is connected to a vacuum pump (not shown) or an exhaust treatment facility via an isolation valve 16 to constitute a vacuum exhaust system. Yes. In a severe accident in which the pressure in the wet well 5 becomes so high that the rupturable plate 11 is ruptured, the differential pressure between the pressure in the wet well and the pressure in the airtight space 13 is set to open the rupturable plate 11. Until the pressure is reached, the airtight space 13 is evacuated by an evacuation system to be in a vacuum state.

  In this embodiment, the probability of occurrence is very small, but in a severe accident that assumes multiple failures of a plurality of safety systems, noncondensable gas is generated in the containment vessel and accumulated in the wet well 5, and the pressure of the containment vessel Becomes higher. At this time, the pressure difference with the hermetic space 13 in a vacuum state becomes larger than the opening setting value of the rupturable plate 11, the rupturable plate 11 is opened, and the gas phase of the wet well is released into the hermetic space 13. The pressure is reduced, and the pressure increase in the containment vessel 3 is suppressed.

  At this time, since the airtight space 13 is in a vacuum, as will be described later, the effect of reducing the pressure is greater than when the airtight space is at normal pressure. Moreover, since oxygen does not exist in the airtight space, the combustible gas contained in the non-condensable gas does not react.

  The first operation method in this system is a method in which the vacuum state of the airtight space 13 is always maintained by operating the vacuum exhaust system and opening the isolation valve 16 regardless of whether there is an accident or not during normal operation of the reactor. is there. In this method, it is necessary to consider that an external pressure is applied to the structural wall forming the airtight space 13 for a long period of time, and a vacuum state is placed in a place adjacent to the upper reactor building 9 where an operator normally enters. If the airtight space 13 exists and the partition wall 12 is temporarily damaged, there is a risk that the worker may be damaged. Therefore, in the present invention, the first operation method was not adopted.

  The airtight space 13 needs to be in a vacuum state immediately before the rupturable plate 11 is opened and the gas phase is released from the wet well 5, and this state is reached after a long time has passed after the accident. is there. Therefore, the second driving method was considered.

  It is known to those skilled in the art that the safety system provided in the nuclear power plant is activated by an accident occurrence signal (high containment pressure, low reactor water level, etc.) of a reactor pipe rupture accident. The evacuation system connected to the airtight space 13 is activated by a signal and the isolation valve 16 is opened. As a result, the gas in the airtight space 13 is exhausted by evacuation by the vacuum exhaust system, and the pressure in the airtight space 13 and the oxygen concentration are reduced when air exists.

  The exhaust at that time is released from the stack to the environment outside the reactor building together with the exhaust such as the ventilation air conditioning system, but the release period is before the start of the release of noncondensable gas from the wet well 5 to the airtight space 13, There is no release to the environment of radioactive materials entrained by non-condensable gases.

  When the pressure in the airtight space 13 decreases or the pressure in the wet well 5 increases, the isolation valve 16 is closed when the pressure is close to the pressure at which the rupturable plate 11 bursts. Stop evacuation to 13.

  With such an operation method, the airtight space 13 is evacuated only during the period from the occurrence of the accident to immediately before the opening of the rupturable plate 11, and the airtight space 13 is airtight when workers are standing in the upper reactor building 9. The situation where the space 13 must be in a vacuum is avoided. Further, when the rupturable plate 11 is opened, the isolation valve 16 is closed so that the reactor building and the system downstream of the isolation valve 16 are isolated from each other. The gas phase containing sexual gas is not released to the environment outside the reactor building.

  As described above, according to this embodiment, the gas phase having a high pressure from the wet well 5 is absorbed by the airtight space 13 in a severe accident of the nuclear power plant, and the effect of suppressing the pressure rise in the containment vessel 3 is exhibited. To do. In addition, since the airtight space for receiving the gas phase released from the wet well 5 is a vacuum at this time, the effect of pressure reduction is increased, and the required space volume of the airtight space 13 is small or the space The effect that the design pressure may be small is exhibited.

  As a result, an increase in the cost of the reactor building can be suppressed, and the time when the airtight space 13 receives the non-condensable gas generated at the time of the accident is after the airtight space 13 is evacuated. Since the reaction of the combustible gas contained in the non-condensable gas with oxygen does not occur or the reaction can be suppressed, the cost required for measures such as the pressure resistance of the airtight space 13 and explosion prevention can be reduced.

  The second embodiment shown in FIG. 2 is an example in which the present invention is applied to a reactor building including a containment vessel 3 in which a steel liner is installed on a concrete boundary wall in a concrete reactor building. It is. In this case, the storage container 3 includes a part in which a part of the upper part is a lid made of steel instead of concrete, and the inside of the loop-shaped thick line frame in FIG. 2 is the storage container region.

  FIG. 2 shows a longitudinal section of the reactor building. The reactor building is composed of a highly airtight containment vessel 3 composed of a reactor vessel 1, a pressure suppression pool 4, a wet well 5, and the like, and a concrete having a relatively low airtightness so as to cover the containment vessel 3. And the area where the annex building was built. The upper reactor building 9 is constructed above both the attached building and the containment vessel 3 and serves as a work space for workers to enter.

  The upper reactor building 9 is provided with a travel path on which an overhead crane (not shown) travels. An operator who enters the upper reactor building 9 performs various operations using a traveling crane traveling on the traveling path. Above the space in which the traveling crane travels, an airtight space 13 having pressure resistance and airtightness is formed by a structural wall 17 so as to cover the upper part of the reactor building. The weight of the structural wall 17 is supported by the reactor building.

  The wet well 5 and the airtight space 13 communicate with each other through a discharge pipe 14 via a rupture plate 11 that is opened when the pressure in the wet well 5 rises and approaches a limit value.

  The structural wall 17 may be a steel plate or a concrete wall with a steel liner attached to a concrete wall having sufficient strength. In the embodiment of FIG. 2, the structural wall 17 is a concrete wall having a sufficient strength and a steel liner pasted thereon.

  Further, an exhaust pipe 15 is connected to the airtight space 13, and the exhaust pipe 15 is connected to a vacuum pump (not shown) or an exhaust treatment facility via an isolation valve 16 to constitute a vacuum exhaust system. Yes.

  Other matters, operation methods, and operations in this embodiment are the same as those in FIG. The effect peculiar to the present embodiment is that, in addition to the effect of the first embodiment, the structural wall 17 that forms the airtight space 13 installed in the upper part of the reactor building is effective against external hazards such as arrival of flying objects such as aircraft falling. It can also be used as a barrier, improving the reliability against external hazards.

  The third embodiment shown in FIG. 3 is similar to the second embodiment in that the airtight space 13 is installed with a structural wall in the upper part of the concrete reactor building and supports the weight of the members constituting the airtight space 13. 18 is installed outside the reactor building between the airtight space 13 and the ground surface.

  Also in this embodiment, the upper reactor building 9 is provided with a traveling path on which an overhead crane (not shown) travels, and workers who have entered the upper reactor building 9 using the traveling crane traveling on the traveling path can perform various kinds of operations. Do work. Above the space in which the traveling crane travels, an airtight space 13 having pressure resistance and airtightness is formed by a structural wall 17 so as to cover the upper part of the reactor building.

  The support wall 18 supports the structural wall 17. The support wall 18 may be constructed so as to support the entire weight of the structural wall 17, or may be constructed so that the weight of the structural wall 17 is dispersedly supported by the reactor building and the support wall 18. In any case, avoid adding the entire weight of the structural wall 17 to the reactor building.

  A channel 19 is formed using the space between the support wall 18 and the reactor building, and the upper end of the channel 19 is communicated with the airtight space 13. This flow path 19 is communicated with the inside of the wet well 5 by the discharge pipe 14, and a rupturable plate 11 is provided in the middle of the discharge pipe 14. Like the first and second embodiments, the rupturable plate 11 is set to be opened by a predetermined differential pressure between the airtight space 13 after the accident and the pressure in the wet well 5. Since the flow path 19 is used to flow a non-condensable gas from the wet well 5 to the airtight space 13 at least between the support wall 18 and the outer wall of the reactor building, the gas is used for the support wall 18. Finish with enhanced airtightness and pressure resistance so that it does not leak into the outside environment or inside the reactor building.

  An exhaust pipe 15 of the vacuum exhaust system connected to the airtight space 13 is also piped to a space between the support wall 18 and the outer wall of the reactor building, and is connected to a vacuum pump and an exhaust treatment facility via an isolation valve 16. Has been.

  The operation method and operation of the vacuum exhaust system and the like in this embodiment are the same as those in the embodiment shown in FIG. 1 and FIG.

  In this embodiment, when the present invention is applied to an existing nuclear power plant, the concrete that forms the ceiling and side walls of the upper reactor building 9 to support the components of the airtight space 13 installed in the upper part of the reactor building. In order not to increase the strength of the wall as much as possible, the support is performed only by the support wall 18 or distributed over the support wall 18 and the reactor building ceiling and side walls of the upper reactor building 9. .

  In this embodiment, the support wall 18 is used to form a non-condensable gas flow path from the wet well 5 to the hermetic space 13. The flow path from the wet well 5 to the hermetic space 13 is shown in FIG. In addition, there is no functional problem even if the pipe is made entirely of steel or the pipe is piped in the space between the support wall 18 and the reactor building. Other technical matters are the same as those of the second embodiment.

  As an effect peculiar to the present embodiment, in addition to the effect of the second embodiment, the support wall 18 is arranged as a strong structural wall on the lateral surface of the reactor building on the ground surface. The barrier to external hazards from the side such as floods will be strengthened.

Next, the pressure reduction effect by the airtight space 13 in each embodiment of the present invention will be described below.
FIG. 4 compares the volume of the airtight space 13 as a parameter, and compares the pressure reduction effect due to the opening of the rupturable plate 11 in a severe accident when the airtight space 13 is at normal pressure and in a vacuum state as in the present invention. Show. This is based on the shape of a typical containment vessel, and in the case where a non-condensable gas is generated at a volume 7.15 times that of the wet well 5 in a severe accident, the horizontal axis represents the volume of the airtight space 13 normalized by the wet well volume. In addition, the vertical axis shows the pressure reduction effect from the case where there is no airtight space 13. The solid line indicates the case where the airtight space is evacuated, and the broken line indicates the case where the airtight space is normal pressure.

  As shown in FIG. 4, the effect of pressure reduction increases as the volume of the airtight space 13 increases. This is because the partial pressure of the non-condensable gas becomes relatively small because the volume for storing the gas phase increases. Moreover, the pressure reduction effect is greater when the airtight space 13 is in a vacuum state than at normal pressure because the partial pressure of air in the airtight space 13 at normal pressure is the partial pressure of the non-condensable gas after being released. Although it contributes, this contribution is lost in vacuum, so the pressure reduction effect is great.

As a result, as in each of the embodiments of the present invention, in the operation in which the airtight space 13 is evacuated immediately before the rupturable plate 11 is opened, the volume of the airtight space 13 when obtaining a certain pressure reduction effect can be reduced.
When the pressure reduction effect indicated by the thin line in the figure is about 0.47 MPa, the volume of the airtight space can be reduced by about 25%. Thereby, the structural wall which forms the airtight space 13 can be reduced, and by extension, cost can be reduced.

  FIG. 5 shows an example of activation and deactivation logic of the vacuum exhaust system in which the airtight space 13 is evacuated when an accident occurs in each embodiment of the present invention. The upper display in FIG. 5 is the startup logic, and the lower display shows the stop logic.

  According to those logics, for the start-up, an accident occurrence signal of a reactor pipe rupture accident (high containment pressure, low reactor water level, etc.) is delayed by a timer, or an operator's start-up operation ( The vacuum pump of the evacuation system (indicated as evacuation pump in FIG. 5) is activated by one of the signals generated by switching on, and the isolation valve 16 installed in the evacuation system is opened.

  In this case, the time delay of the accident occurrence signal with the timer is intended for severe accidents with a very low occurrence frequency exceeding the design standard accident, so there is time to start up, so it is an error signal. This is to give the operator time to determine whether to use the margin. If it is determined that the signal is an error signal, the activation signal is reset by the stop operation of the operator in the logic shown in the lower part of FIG.

  For stopping the evacuation system, as in the logic shown in the lower part of FIG. 5, the pressure in the airtight space 13 is measured, and when the pressure in the airtight space 13 is sufficiently reduced, the pressure in the wet well 5 is measured, When the pressure rises to just before the set pressure at which the rupture disc 11 is opened, when radioactivity is detected in the exhaust from the stack (high radioactivity level), or when the operator performs a stop operation (switch off) Is transmitted, the vacuum pump (shown as an exhaust pump in FIG. 5) is stopped and the isolation valve 16 is closed.

  Here, the signal of high radioactivity level in the exhaust from the stack is included in order to more reliably avoid the release of radioactive material to the environment. Note that. Each embodiment of the present invention is intended for severe accidents and is a part of management at the time of an accident, so that multiplexing of control systems is not essential.

  INDUSTRIAL APPLICABILITY The present invention can be used as equipment for preventing a pressure in a reactor containment vessel that stores a nuclear reactor from becoming an overpressure state at the time of an accident in a boiling water nuclear power plant.

DESCRIPTION OF SYMBOLS 1 Reactor vessel 2 Reactor containment internal structure 3 Reactor containment vessel 4 Pressure suppression pool 5 Wet well 6 Equipment installation area 7 Fuel pool 8 Equipment temporary storage pool 9 Upper reactor building 10 Steel container 11 Rupture plate 12 Section Wall 13 Airtight space 14 Discharge pipe 15 Exhaust pipe 16 Isolation valve 17 Structural wall 18 Support wall 19 Flow path

Claims (8)

  An airtight space for absorbing the pressure in the reactor containment vessel is provided above the traveling space of the traveling crane installed in the upper reactor building of the reactor building, and the inside of the airtight space and the wet well of the reactor containment vessel is provided. And a reactor containment vessel overpressure preventive device in which a vacuum exhaust system is connected to the airtight space.   2. The reactor building according to claim 1, wherein the reactor building is formed by covering the reactor containment vessel and the upper reactor building with a steel vessel, and the upper reactor building is partitioned into upper and lower parts by a partition wall. Is formed as the airtight space. An overpressure prevention device for a reactor containment vessel.   2. The reactor building according to claim 1, wherein the reactor building is a concrete building including the concrete reactor containment vessel, and the airtight space is provided in an upper part of an upper reactor building of the reactor building, A reactor containment vessel overpressure prevention device characterized in that the above-mentioned structural members are supported by the reactor building.   2. The reactor building according to claim 1, wherein the reactor building is a concrete building including the concrete reactor containment vessel, and the airtight space is provided in an upper part of an upper reactor building of the reactor building, A reactor containment vessel overpressure prevention apparatus characterized in that the above-mentioned structural member is supported by a support wall provided on the side of the reactor building.   The reactor containment vessel overpressure prevention apparatus according to claim 4, further comprising a flow path communicating with the airtight space and the inside of the wet well in a space between the support wall and the reactor building.   The reactor containment vessel overpressure prevention apparatus according to claim 5, wherein an exhaust pipe to the vacuum exhaust system is provided in a space between the support wall and the reactor building. The non-condensable gas is received from the wet well in the reactor containment vessel by opening the rupture disc into the airtight space installed above the traveling space of the traveling crane installed in the upper reactor building of the reactor building. An operation method for suppressing an increase in pressure inside the reactor containment vessel,
The vacuum exhaust system connected to the airtight space via an isolation valve is evacuated after the event involving the state in which the pressure in the wet well increases, the vacuum exhaust system is evacuated, and the bursting A method of operating a reactor containment vessel overpressure prevention apparatus, wherein the isolation valve is closed before the plate is opened to stop the vacuuming of the hermetic space.   8. The evacuation is started by opening the isolation valve based on a signal generated by the occurrence of an event accompanied by a state in which the pressure in the wet well space is increased, and the pressure in the wet well is changed to the rupture disc. A method of operating an overpressure prevention device for a reactor containment vessel, wherein the vacuuming of the hermetic space is stopped and the isolation valve is closed before reaching the opening value.

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