JP6178249B2 - Vent filter system equipment - Google Patents

Description

  The present invention relates to a vent filter system facility installed in a nuclear power plant, and more particularly to a vent filter system that discharges gas in a reactor containment vessel to the outside of the reactor containment vessel at the time of an accident.

  The vent filter system is a facility that removes radioactive substances in exhaust gas (hereinafter referred to as “vent gas”) generated by a vent operation performed in order to prevent a pressure increase in the reactor containment vessel in the event of a nuclear reactor accident. At that time, prevention of temperature increase under loss of power supply for a filter that handles high-temperature exhaust and measures for increasing the dose rate around the filter due to accumulated radioactive substances have been a challenge.

  Patent Document 1 and Patent Document 2 are known to prevent the rise of the temperature of the vent filter system and shield the periphery of the filter even when power is lost.

  In Patent Document 1, the vent filter unit is installed in a cooling pool provided outside the reactor containment vessel, and the cooling water in the cooling pool causes the decay heat of radioactive material captured by the filter constituting the vent filter unit. Reduces temperature rise. Note that the amount of cooling water stored in the cooling pool is obtained in advance by obtaining the amount of cooling water evaporated due to decay heat, and even if the power supply is lost, the amount of cooling water that can cool the filter unit for a desired period of time. Is to be stored.

  Further, in Patent Document 2, the vent filter unit is submerged in the pressure suppression pool in the reactor containment vessel, and the water in the pressure suppression pool is circulated by using heat at which the vent filter unit becomes hot during the vent operation. The vent filter unit is cooled by a simple mechanism.

JP-A-4-204096 Japanese Patent Laid-Open No. 7-151889

  In recent years, following the accident at the Fukushima Daiichi Nuclear Power Station, it has been studied to install a vent filter system installed at the nuclear power station outside the reactor building in which the reactor containment vessel is housed.

  In Patent Document 1, although a vent filter unit is installed in a cooling pool provided outside the reactor containment vessel, this cooling pool is installed in the reactor building that houses the reactor containment vessel. Is common. Accordingly, no consideration is given to installing the vent filter unit outside the reactor building.

  Further, in order to shield the vent filter unit from the surrounding environment, in order to provide the cooling water pool in the reactor building, there is a possibility that it is difficult to obtain a sufficient shielding effect due to the limitation of the arrangement space. When remodeling an existing nuclear reactor building, it is necessary to newly add a building for shielding the vent filter unit, and it becomes difficult to extend the construction period, that is, to build in a short period of time.

  In Patent Document 2, the vent filter unit is installed in the pressure suppression pool in the reactor containment vessel, and is not considered to be installed outside the reactor building. Since it is the structure which acquires a shielding effect by arrange | positioning in a nuclear reactor containment vessel, the structure for acquiring the shielding effect at the time of installing a vent filter unit in the reactor building outdoor is not considered.

  The present invention provides a vent filter system facility capable of improving the shielding effect on the surrounding environment and shortening the construction period.

  In order to solve the above problems, a vent filter system facility according to the present invention includes a vent filter unit that removes radioactive substances contained in vent gas discharged from a containment vessel and supplies the vent gas after removal of radioactive substances to an exhaust tower. An open pit that is provided outside the reactor building that houses the reactor containment vessel and communicates with the atmosphere through an open port, and a shielding water storage tank that stores shielding water, and is provided in the open pit. The vent filter unit is disposed, and shielding water is supplied from the shielding water storage tank into the open pit by its own weight.

  ADVANTAGE OF THE INVENTION According to this invention, the vent filter system equipment which can improve the shielding effect to surrounding environment and can shorten a construction work period can be provided.

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

It is a schematic block diagram of the vent filter system equipment which concerns on one Example of this invention. It is a figure which shows the operating state of the vent filter system equipment shown in FIG. It is a schematic block diagram of the vent filter system equipment of a comparative example. It is a schematic block diagram of the vent filter system equipment which concerns on the other Example of this invention. It is a figure which shows the operating state of the vent filter system equipment shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a vent filter system facility according to a first embodiment of the present invention. As shown in FIG. 1, the vent filter system facility of the present invention is a vent filter unit installed in an open pit 2 provided at a position away from a reactor building 7 that houses a reactor containment vessel (not shown). 1. A shielding water storage tank 3 for storing shielding water 8 to be supplied into the open pit 2 is provided.

  The vent filter unit 1 contains absorbed water 9 mixed with a chemical capable of adsorbing radioactive substances (for example, iodine, cesium) contained in steam (vent gas) discharged from the reactor containment vessel during the vent operation. A vent introduction pipe 10 that accommodates and vents the vent gas discharged from the reactor containment vessel into the absorption water 9, and a vent discharge pipe that guides the vapor from which radioactive substances have been removed by passing through the absorption water 9 to the exhaust tower 6. 12 is connected.

  The storage container of the vent filter unit 1 is filled with the absorption water 9 so that the water surface is located above the vent introduction pipe 10 and below the vent discharge pipe 12. Radioactive substances contained in the vent gas introduced from the vent introduction pipe 10 are captured and removed in the absorbed water 9. The vent gas from which the radioactive substance has been removed moves to the gas phase portion of the vent filter unit 1 and is released from the exhaust tower 6 into the atmosphere via the vent exhaust pipe 12. The storage container of the vent filter unit 1 is made of stainless steel, and a vent gas blowing pipe 11 is provided at the end of the vent introduction pipe 10 extending into the storage container. The vent gas blowing pipe 11 is constituted by, for example, a pipe extending substantially parallel to the bottom surface of the storage container of the vent filter unit 1, and a plurality of fine holes are formed on the surface. The vent gas is dispersed and blown out in the absorption water 9 through the fine holes, whereby the capture of the radioactive substance to the drug in the absorption water 9 is promoted. The vent gas blowing pipe 11 is not limited to the above, and may have a configuration in which a plurality of fine holes are formed on the surface of a disk-shaped hollow body.

  The vent filter unit 1 is not limited to the one that captures radioactive substances contained in the vent gas by the above-described absorption water 9, but a metal filter (not shown) is disposed in the gas phase portion of the vent filter unit 1 to absorb the absorption water. 9 may be used to efficiently remove radioactive substances in the vent gas.

  As shown in FIG. 1, the vent filter system equipment is vented so that the upper end portion of the vent filter unit 1 is lower than the floor surface of the reactor building 7 by a predetermined height h2 outside the reactor building 7. An open pit 2 that houses the filter unit 1 and whose upper part is open to the atmosphere, and a bottom surface thereof is at a predetermined height h1 above the upper end of the vent filter unit 1 and is supplied to the open pit 2 A shielding water storage tank 3 for storing 8, one end of which is connected to the bottom of the shielding water storage tank 3 via an opening / closing valve 5, and the other end is an opening provided on the side wall of the open pit 2 or an atmosphere opening portion. A shielding water supply pipe 4 is provided which is connected to any one and flows through the shielding water 8.

  Here, the shielding water 8 stored in the shielding water storage tank 3 may be either water or absorption water 9, and the on-off valve 5 is a valve that can be opened and closed by either remote operation or operator operation. It is done. Thereby, even if the power supply is lost, the shielding water 8 can be supplied into the open pit 2. Further, since the bottom surface (installation surface) of the shielding water storage tank 3 is located above the upper end of the vent filter unit 1 installed in the open pit 2 by a predetermined height h1, the on-off valve 5 is described above. Thus, the shielding water 8 is supplied into the open pit 2 through the shielding water supply pipe 4 by its own weight. Thereby, it is possible to supply the shielding water 8 even when the power supply is lost, in particular, without requiring a power mechanism such as a pump.

  The inner wall of the open pit 2 is reinforced concrete and has a stainless steel lining, and since the shielding effect is achieved by the shielding water 8, the wall thickness thereof does not need to be as strong as the reactor building 7 or the like.

  In the present embodiment, the case where the reactor building 7 and the shielding water storage tank 3 are constructed on the ground in the site of the nuclear power plant will be described as an example. However, the reactor building 7 is partially embedded in the ground. The present invention can also be applied to a structure. In this case, the distance in the height direction between the floor surface of the reactor building 7 and the upper end portion of the vent filter unit 1 is smaller than h2, or the floor surface of the reactor building 7 is below the upper end portion of the vent filter unit 1. Even when it is located, the vent gas discharged from the reactor containment vessel at the time of the accident is supplied to the vent filter unit 1 through the vent introduction pipe 10 due to its vapor pressure.

  Next, the operation at the time of the vent operation will be described. FIG. 2 is a diagram showing an operating state of the vent filter system facility shown in FIG.

  If the pressure in the reactor containment vessel rises in the event of a nuclear reactor accident, when the power supply is secured, the on-off valve 5 is opened by remote operation, and the dead weight passes through the shielding water supply pipe 4 due to its own weight. The shielding water 8 is supplied from the shielding water storage tank 3 to the open pit 2. The shielding water 8 is supplied at least until the water surface is positioned a predetermined height above the upper end of the vent filter unit 1. The shielding water 8 is supplied until the water level of the shielding water 8 reaches a position where the shielding function is achieved, for example, 5 m or more above the upper end of the vent filter unit 1.

  Thereafter, a vent gas containing a radioactive substance is supplied from the inside of the reactor containment vessel to the vent filter unit 1 through the vent introduction pipe 10. The vent gas is dispersed from the fine openings of the vent gas blowing pipe 11 and blown out to the absorption water 9 and moves to the gas phase in the vent filter unit 1. During the transition to the gas phase, the radioactive substance contained in the vent gas is captured by the chemical in the absorption water 9, and the vent gas from which the radioactive substance has been removed is guided to the exhaust tower 6 via the vent exhaust pipe 12, and the exhaust tower 6 is released into the atmosphere.

  A water level meter (not shown) is installed in the open pit 2, and the shielding water 8 is supplied into the open pit 2 until the water level is reached based on the measurement value from the water level meter. Since the vicinity of the water surface of the shielding water 8 supplied into the open pit 2 is at a temperature of 100 ° C. or higher, the water level meter is not only a floating type but also a thermocouple near the water surface, below the water surface, The water level may be measured by detecting the temperature difference between the phases.

  Thus, even if the amount of the shielding water 8 in the open pit 2 is reduced when the vent filter unit 1 is in operation, the open pit 2 is used by the shielding water 8 supplied into the open pit 2. It is possible to shield the leakage of radiation to the surrounding environment and to cool the vent filter unit 1.

  If the pressure in the reactor containment vessel rises due to a loss of power in the event of a reactor accident, the on-off valve 5 is opened by manual operation by the operator, and the shielding water is used until a predetermined water level is reached. 8 is supplied to the open pit 2.

  Here, the comparative example which does not have the vent filter system installation of this invention is demonstrated. The schematic block diagram of the vent filter system installation of a comparative example is shown in FIG. As shown in FIG. 3, in the comparative example, the vent filter unit 1 is installed and shielded in the vent filter unit storage tank 20. The vent filter unit storage tank 20 includes a sufficiently thick shielding wall made of reinforced concrete on the side wall and the ceiling surface of the vent filter unit storage tank 20, and the entire vent filter unit 1 is covered with the above-described shielding wall. Thereby, the leakage of the radiation to the surrounding environment of the vent filter storage tank 20 is shielded.

  In the structure of such a comparative example, the housing of the vent filter unit storage tank 20 is also large, and a large installation space is required to install the vent filter unit 1. Further, since a reinforced concrete ceiling having a considerable thickness is also required on the upper portion of the vent filter unit 1, measures for earthquake resistance are required, and the amount of reinforced concrete to be used increases. Further, when the vent filter unit 1 is operated in a power loss state, the atmosphere in the vent filter unit storage tank 20 becomes a high temperature environment due to the heat of the vent gas discharged from the reactor containment vessel. Therefore, in order to maintain the temperature in the vent filter unit storage tank 20 below a predetermined temperature, a ventilation air conditioning system with an emergency power supply is required. Therefore, in the structure of the comparative example, the construction cost increases and it is difficult to shorten the construction period.

  On the other hand, in the vent filter system equipment of the present embodiment, as described above, the vent filter unit 1 is installed in the open pit 2 and is opened by supplying the shielding water 8 into the open pit 2 during the vent operation. Since the radiation shielding to the surrounding environment of the mold pit 2 is shielded, the amount of reinforced concrete used can be reduced, construction costs can be reduced, and the vent filter system equipment can be simplified, thus shortening the construction period. It becomes.

  According to the present embodiment, it is possible to realize a vent filter system facility capable of improving the shielding effect on the surrounding environment and shortening the construction period.

  FIG. 4 shows a schematic configuration diagram of a vent filter system facility according to a second embodiment of the present invention. The same components as shown in FIGS. 1 and 2 are denoted by the same reference numerals. The present embodiment is different from the first embodiment in that a water control device 15 is newly provided between the open pit 2 and the seawall 14.

  As shown in FIG. 4, the water control device 15 is disposed between the tide bank 14 and the open pit 2 where the vent filter unit 1 is installed, and enters the site of the nuclear power plant across the tide bank 14. Seawater 13 is temporarily stored, and the impact caused by inflowing seawater 13 is reduced. The water control device 15 has a function of causing the inflow seawater 13 after temporary storage or impact relaxation to flow into the open pit 2 as shielding water.

  As the water control device 15, for example, provided on the tide bank 14 side of the open-air pit 2 to the atmosphere opening, a partition wall (movable partition wall) that opens and closes by the water pressure of the flowing seawater 13, or enters the tide bank 14. A fixed partition provided only to mitigate the impact of the seawater 13 (deceleration of the incoming seawater) is used. In this case, the seawater 13 that has collided with the fixed partition and has been decelerated subsequently functions as an overflow type shielding water supply mechanism that passes over the fixed partition and flows into the open pit 2.

  Next, the operation during the venting operation will be described. FIG. 5 shows the operating state of the vent filter system facility shown in FIG.

  If a nuclear reactor accident caused by an earthquake, the pressure inside the reactor containment vessel increased, and the sea level increased due to the tsunami caused by the earthquake. Enter the site of the power plant. When the water control device 15 is the fixed partition wall, the seawater 13 collides with the fixed partition wall that is the water control device 15, and the inflow seawater is decelerated. At this time, the fixed partition functions as a weir, and the seawater 13 after deceleration flows into the open pit 2. By decelerating the inflowing seawater 13 in this way, the vent filter unit 1 can be prevented from being damaged by the impact of the inflowing seawater 13.

  In the state where the power source is secured, the water level of the inflowing seawater 13 in the open pit 2 is, for example, a vent filter based on the measured value from the water level meter installed in the open pit 2 as in the first embodiment. Vent gas is supplied to the vent filter unit 1 via the vent introduction pipe 10 when it reaches 5 m or more above the upper end of the unit 1. The vent gas from which the radioactive substance has been removed by the vent filter unit 1 is guided to the exhaust tower 6 via the vent exhaust pipe 12 and is released from the exhaust tower 6 into the atmosphere. Thereby, the leakage of the radiation to the surrounding environment of the open pit 2 is shielded by the seawater 13 in the open pit 2, and the accident convergence work in the surroundings becomes possible.

  In addition, when the water level of the inflow seawater 13 in the open pit 2 is less than the predetermined water level, the shortage of the inflowing seawater 13 is opened via the shielding water supply pipe 4 by opening the on-off valve 5. By supplying 8 into the open pit 2, radiation leakage to the environment around the open pit 2 can be shielded, and the vent filter unit 1 can be cooled.

  In the case of a power loss state, the water level of the seawater 13 in the open pit 2 is confirmed by the operator's visual observation, and supply of vent gas is started via the vent introduction pipe 10, or the on-off valve 5 is manually operated. Supply of the shielding water 8 into the open pit 2 by operation is performed.

  In this embodiment, since seawater is used as the shielding water, it is desirable to apply a heat resistant resin coating to the corrosion resistant material in order to prevent corrosion of the vent filter unit 1.

  According to the present embodiment, as compared with the first embodiment, by using the inflow seawater 13 as shielding water, the amount of work in an emergency such as an operation of the on-off valve 5 by the operator can be reduced.

  Moreover, the damage risk of the vent filter unit 1 by the impact of inflow seawater, such as a tsunami, can be prevented.

  In addition, it is possible to realize a vent filter system facility that can improve the shielding effect on the surrounding environment and shorten the construction period.

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

DESCRIPTION OF SYMBOLS 1 ... Vent filter unit 2 ... Open type pit 3 ... Shielding water storage tank 4 ... Shielding water supply piping 5 ... Open / close valve 6 ... Exhaust tower 7 ... Reactor building 8 ...... Shielding water 9 ... Absorbing water 10 ... Vent introduction pipe 11 ... Vent gas blowing pipe 12 ... Vent discharge pipe 13 ... Sea water 14 ... Seawall 15 ... Water control device 20: Vent filter unit storage tank

Claims (8)

A vent filter unit that removes radioactive substances contained in the vent gas discharged from the reactor containment vessel and supplies the vent gas after removal of the radioactive substances to the exhaust tower;
An open pit that is provided outside the reactor building that houses the reactor containment vessel and communicates with the atmosphere through an open port;
A shielding water storage tank for storing shielding water;
A vent filter system facility, wherein the vent filter unit is disposed in the open pit, and shielding water is supplied from the shielding water storage tank into the open pit by its own weight. The vent filter system facility according to claim 1,
A vent filter system facility, wherein an installation surface of the shielding water storage tank is located above a predetermined height from an upper end portion of a vent filter unit disposed in the open pit. The vent filter system facility according to claim 1,
A water control device provided between an opening of the open pit and a sea levee, for mitigating the impact of seawater flowing over the seawater and supplying the inflow seawater after the impact relaxation into the open pit A vent filter system facility comprising: The vent filter system facility according to claim 2 ,
One end is connected to the shielding water storage tank via an on-off valve, the other end is connected to an opening formed on the side wall of the open pit, and has a shielding water supply pipe through which the shielding water flows.
A vent filter system facility for supplying shielding water to the open pit by its own weight through the shielding water supply pipe by operating the on-off valve. The vent filter system facility according to claim 3 ,
One end is connected to the shielding water storage tank via an on-off valve, the other end is connected to an opening formed on the side wall of the open pit, and has a shielding water supply pipe through which the shielding water flows.
A vent filter system facility for supplying shielding water to the open pit by its own weight through the shielding water supply pipe by operating the on-off valve . In the vent filter system equipment according to claim 2 or 4 ,
When the level of the shielding water in the open pit reaches a predetermined level above the upper end of the vent filter unit, vent gas discharged from the reactor containment vessel is supplied to the vent filter unit. Vent filter system equipment. In the vent filter system equipment according to claim 3 or 5 ,
When the water level of the inflow seawater in the open pit reaches a predetermined water level above the upper end of the vent filter unit, vent gas discharged from the reactor containment vessel is supplied to the vent filter unit. Vent filter system equipment. In the vent filter system equipment according to any one of claims 3, 5, and 7,
Vent filter system facility characterized in that the water control device is a movable partition wall that relaxes the impact of the inflowing seawater and opens and closes by the water pressure of the inflowing seawater, or a fixed partition wall that relaxes the impact of the inflowing seawater .

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