JP2011174773A - Catalytic recombination device and catalyst used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the recombination performance of a catalyst even if a catalytic recombination device receives disturbance. <P>SOLUTION: In the catalytic recombination device for a nuclear power plant which includes catalyst cartridges filled with a catalyst for recombining a flammable gas, a chimney inside which the catalyst cartridges are laid out and a hood placed above the chimney, cavities are formed inside the catalyst. The recombination performance of the catalyst can be maintained even if the catlytic recombination device receives disturbance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a catalytic recombination apparatus and a catalyst used in the catalytic recombination apparatus.

  In a light water nuclear power plant, when a coolant loss accident occurs where the reactor primary cooling system piping connected to the reactor pressure vessel breaks, the water used as the coolant is radiolyzed, generating hydrogen gas and oxygen gas. . When the cooling function of the core is temporarily impaired and the temperature of the fuel cladding tube rises, water vapor and zirconium in the fuel cladding tube react to generate hydrogen gas. These hydrogen gases are released into the reactor containment vessel from a damaged portion of the reactor primary cooling system piping, and the hydrogen gas concentration in the reactor containment vessel gradually increases. If the increase in the concentration of the released hydrogen gas is left as it is, it will be in a flammable state in an atmosphere with a hydrogen gas concentration of 4 vol% or more and an oxygen gas concentration of 5 vol% or more. There is a need to.

  Patent Document 1 discloses a catalytic recombination apparatus using a catalyst that oxidizes hydrogen gas inside a reactor containment vessel including a dry well that houses a reactor pressure vessel and a pressure suppression chamber.

Japanese Patent Laid-Open No. 10-227885

  The catalytic recombination apparatus of Patent Document 1 does not consider the possibility that the catalytic recombination apparatus may be overturned or damaged due to a disturbance such as a jet flow ejected from the pipe when the coolant pipe is broken. Even when the catalytic recombination device is disturbed and the device falls or breaks down, it is necessary to maintain the recombination performance of the catalyst in order to suppress the hydrogen gas concentration and the oxygen gas concentration below a certain value.

  Therefore, an object of the present invention is to maintain the recombination performance of the catalyst even when the catalytic recombination apparatus is disturbed.

  The present invention is characterized in that a cavity is provided inside a catalyst used in a catalytic recombination apparatus of a nuclear power plant.

  According to the present invention, it is possible to maintain the recombination performance of the catalyst even when the catalytic recombination apparatus is disturbed.

The perspective view of a catalyst cartridge is shown. Sectional drawing of the catalyst (Example 1) with which a catalyst cartridge is filled is shown. The outline | summary of the catalytic recombination apparatus of Example 1 is shown. The perspective view of the catalyst-type recombination apparatus of Example 2 is shown. Sectional drawing of the catalyst-type recombination apparatus of Example 2 is shown. Sectional drawing of the catalytic recombination apparatus of Example 3 is shown. The perspective view of the catalyst-type recombination apparatus of Example 4 is shown. The perspective view of the catalyst-type recombination apparatus of Example 4 is shown. The perspective view of the catalyst-type recombination apparatus of Example 4 is shown. The perspective view of the catalyst-type recombination apparatus of Example 4 is shown. The perspective view of the catalyst-type recombination apparatus of Example 4 is shown. A schematic diagram of a nuclear power plant is shown. Sectional drawing of the catalyst (Examples 2-4) with which a catalyst cartridge is filled is shown.

  The following examples relate to a catalytic recombination apparatus having a catalyst for treating a combustible gas leaking into a reactor containment vessel when a loss of coolant accident occurs or when a severe severe accident occurs.

  Examples of the present invention will be described below.

  FIG. 10 shows a schematic diagram of a nuclear power plant. The boiling water nuclear power plant that is the nuclear power plant of this embodiment includes a reactor pressure vessel 2, a reactor containment vessel 30, a reactor building 9, and a catalytic recombination device 16.

  The reactor pressure vessel 2 has a core 1 inside. The reactor containment vessel 30 includes a reinforced concrete portion 31, a liner 32 that covers the inner surface of the reinforced concrete portion 31, and the top head 6. The liner 32 is used to ensure the airtightness of the reactor containment vessel 30 and is attached to the inner side of the reinforced concrete portion 31 having a pressure resistance function. The top head 6 is detachably attached to the reinforced concrete portion 31 with bolts using a flange 15 provided at the upper end portion of the concrete portion 31. The reactor pressure vessel 2 is installed on a cylindrical pedestal 33 provided in the reactor containment vessel 30. A diaphragm floor 34 is attached to the reactor containment vessel 30 and the pedestal 33. The internal space of the reactor containment vessel 30 is separated into a wet well 5 and a dry well which are pressure suppression chambers by a pedestal 33 and a diaphragm floor 34. The dry well includes an upper dry well 3 located above the diaphragm floor 34 and a lower dry well 4 located inside the pedestal 33 below the reactor pressure vessel 2. Within the wet well (pressure suppression chamber) 5 is a suppression pool 35 filled with cooling water. A plurality of vent passages 36 communicating with the upper dry well 3 and the lower dry well 4 and formed in the pedestal 33 open into the suppression pool 35 in the wet well (pressure suppression chamber) 5.

  The reactor containment vessel 30 is installed in the reactor building 9. The floor formed in the reactor building 9 is connected to the reinforced concrete part 31. A reactor well 7 is formed in the reactor building 9 above the reactor containment vessel 30. A reactor well ceiling 8 is disposed above the reactor well 7 and is removably attached to the reactor building 9. In FIG. 10, the structure of the reactor building 9 above the reactor well ceiling 8 is omitted. When the operation of the reactor is stopped and the fuel assembly (not shown) loaded in the core 1 is replaced, water is stretched in the dry well, and the reactor well ceiling 8, the top head 6 and the reactor Each of the lids of the reactor pressure vessel 2 is removed. At the time of fuel exchange, a fuel assembly (not shown) moving on the operation floor above the reactor well 7 is taken out of the core 1 and transported to the fuel storage pool via the reactor well 7. A new fuel assembly follows the reverse route from the fuel pool and is loaded into the core 1.

  Various rooms are formed in the reactor building 9 outside the reactor containment vessel 30. A piping 10 having a valve 11 is installed in the piping chamber 14. The piping 10 penetrating the reactor containment vessel 30 is concentrated in the piping chamber 14. A suction duct 13 of an air conditioning facility (not shown) is disposed in the room 37. An access tunnel 38 penetrating the pedestal 33, the wet well (pressure suppression chamber) 5 and the reactor containment vessel 30 is provided. The access tunnel 38 connects the lower dry well 4 and the room 39. An openable / closable equipment carry-in hatch 12 that ensures airtightness is provided at the end of the access tunnel 38 on the room 39 side. The equipment carry-in hatch 12 exists in the room 39.

  The catalytic recombination device 16 is disposed inside the reactor containment vessel 30. In this embodiment, the catalytic recombination device 16 is fixed to the floor surface of the diaphragm floor 34 and the inner wall surface of the wet well 5.

  FIG. 2 shows an outline of the catalytic recombination device 16 of this embodiment. The internal space 45 of the chimney 41, which is a flow path opened up and down, includes a plurality of catalyst cartridges 21 arranged at intervals. Fig.1 (a) shows the perspective view of a catalyst cartridge. The catalyst cartridge 21 has a box shape in which catalyst particles are filled inside and a large number of holes are provided on the side surface. Further, the catalyst cartridge 21 has a function of combining hydrogen and oxygen flowing into the inside from the side surface thereof by the action of the catalyst. A hood 40 is provided in the opening 42 above the chimney 41 so that the catalyst is not directly wetted by water ejected from the storage container spray 53. The structure of the chimney 41, the hood 40, and the catalyst cartridge 21 is manufactured by bending a stainless steel thin plate material, and an inspection door is provided so that the catalyst cartridge can be taken out for inspection or replacement.

  Then, hydrogen gas and oxygen gas, which are combustible gases 43, flow into the catalytic recombination device 16 from the lower opening and are guided to the plurality of catalyst cartridges 21. The hydrogen gas and oxygen gas are recombined by the catalyst layer included in the catalyst to become water. As a result, the combustible gas concentration in the reactor containment vessel 30 is controlled to be less than the combustible limit, and combustion of the combustible gas can be prevented. The gas 44 flowing between the catalyst cartridges 21 is discharged upward from the opening 42.

  FIG. 1B shows a cross-sectional view of the catalyst 17 filled in the catalyst cartridge. The catalyst 17 is a spherical object and forms a three-layer structure. The catalyst holding carrier 20 is made of alumina. The catalyst layer 19 is a layer that covers the outer surface of the catalyst holding carrier 20 and is formed of palladium. The water repellent coating 18 is a layer that covers the outer surface of the catalyst layer 19 in order to protect the catalyst layer 19 from water. The catalyst 17 of this example has a cavity 47 at the center.

  Thus, the effect by making the center part of the catalyst 17 a cavity is demonstrated.

  When a coolant loss accident occurs in which the reactor primary coolant pipe 50 connected to the reactor pressure vessel 2 breaks, the high-temperature cooling water in the reactor pressure vessel 2 becomes steam, and is It spouts into the dry well 3. Here, when the vapor | steam ejected from the fracture | rupture location 51 contacts the catalytic recombination apparatus 16 directly, the catalytic recombination apparatus 16 may fall down. When the catalyst cartridge 21 is damaged due to overturning, the catalyst 17 filled in the catalyst cartridge 21 leaks from the opening 42 of the apparatus, and the catalyst 17 flows through the floor surface of the diaphragm floor 34 and flows into the suppression pool from the vent passage 36. To do. At this time, by providing a hollow portion inside the catalyst and making the catalyst 17 lighter than the specific gravity of water, it is possible to prevent the catalyst from floating on the pool water surface and settling on the bottom surface of the pool. .

  In addition, an ECCS pump 52 for guiding the suppression pool water to the reactor pressure vessel is provided in the water of the suppression pool. Since the catalyst of this embodiment floats on the water surface without being precipitated in the water of the suppression pool, clogging of the ECCS pump 52 can be prevented.

  In general, the catalyst cannot treat the combustible gas when the catalyst surface is covered with water (submerged). Therefore, when the catalyst floats on the surface of the suppression pool, the combustible gas can be treated even when the catalyst leaks out of the apparatus. Thus, even when the catalytic recombination apparatus is subjected to disturbance, the recombination performance of the catalyst can be maintained.

  FIG. 3A shows a perspective view of the catalytic recombination apparatus of this embodiment, and FIG. 3B shows a cross-sectional view. Compared with FIG. 2, the catalytic recombination device 16 of the present embodiment is provided with a net-like structure 22 in the lower opening into which hydrogen gas and oxygen gas flow and the upper opening of the hood. Different. The mesh size of the structure is formed smaller than the diameter of the catalyst particles. By covering the opening of the catalytic recombination device with a network structure, it is possible to prevent the catalyst from flowing out of the device even if the catalytic recombination device falls.

  FIG. 11 shows the catalyst 17a filled in the catalytic recombination apparatus of this embodiment. The catalyst 17a of this example is not provided with a cavity as compared with Example 1. Since the catalyst-type recombination apparatus of this embodiment prevents the catalyst from flowing out to the outside, the catalyst shown in FIG. 11 can be used. If a catalyst having a cavity as shown in FIG. 1B is used, the recombination performance of the catalyst can be maintained even when the network structure 22 is broken and the catalyst flows out to the outside. Is possible.

  FIG. 4 shows a cross-sectional view of the catalytic recombination apparatus of this example. Compared to FIG. 2, the catalytic recombination device 16 of the present embodiment is different in that an airbag 23 is provided in a lower opening through which hydrogen gas and oxygen gas flow and an upper opening of the hood. The air bag 23 has a function of automatically inflating and closing the opening when the catalytic recombination apparatus falls. Thus, by providing an airbag at the opening of the catalytic recombination device, it is possible to prevent the catalyst from flowing out of the device even if the catalytic recombination device falls.

  FIG. 11 shows the catalyst 17a filled in the catalytic recombination apparatus of this embodiment. The catalyst 17a is not provided with a cavity as compared with the first embodiment. With the catalytic recombination device of this embodiment, the catalyst shown in FIG. 11 can be used because the catalyst is prevented from flowing out. If a catalyst having a cavity as shown in FIG. 1B is used, it is possible to maintain the recombination performance of the catalyst even when the airbag 23 is broken and the catalyst flows out to the outside. .

  5 to 9 show perspective views of the catalytic recombination apparatus of this embodiment. Compared with FIG. 2, the catalytic recombination device 16 of FIG. 5 is different in that an arc-shaped leg 24 is provided. The catalytic recombination apparatus of FIG. 5 can prevent the apparatus from falling because the entire apparatus shakes along the arc portion even when a disturbance is applied.

  Further, the catalytic recombination device 16 of FIG. 6 is different in that a bowl-shaped leg 25 is provided. The catalytic recombination apparatus of FIG. 6 can prevent the apparatus from falling because the entire apparatus shakes along the bowl shape even when a disturbance is applied.

  The catalytic recombination device 16 of FIG. 7 is different in that a movable caster 26 is provided. The catalytic recombination apparatus of FIG. 7 can prevent the apparatus from falling because the entire apparatus is horizontally moved by the casters 26 even when a disturbance is applied.

  The catalytic recombination device 16 of FIG. 8 is different in that a spring-like leg 27 is provided. The catalytic recombination apparatus of FIG. 8 can prevent the apparatus from falling because the spring absorbs the shaking of the apparatus even when a disturbance is applied.

  The catalyst type recombining device 16 shown in FIG. 9 is different in that a seismic mat 28 is provided at the lower portion of the leg to prevent the vibration from being transmitted to the device.

  Thus, by providing the legs of FIGS. 5 to 9, even if a disturbance occurs in the catalytic recombination device, the catalytic recombination device is prevented from falling and the catalyst is prevented from flowing out from the inside of the device. be able to.

  FIG. 11 shows the catalyst 17a filled in the catalytic recombination apparatus of this embodiment. The catalyst 17a is not provided with a cavity as compared with the first embodiment. With the catalytic recombination device of this embodiment, the catalyst shown in FIG. 11 can be used because the catalyst is prevented from flowing out. If a catalyst having a cavity as shown in FIG. 1B is used, the recombination performance of the catalyst can be maintained even when the catalyst flows out.

  The present invention relates to a catalytic recombination apparatus having a catalyst for treating a flammable gas that leaks into a reactor containment vessel when a loss of coolant accident occurs or when a severe accident occurs. When the apparatus is broken or falls, the catalyst that has flowed out of the apparatus into the suppression pool water floats on the water surface, so that the ECCS pump that uses the suppression pool as a water source can be prevented from being clogged.

DESCRIPTION OF SYMBOLS 1 Reactor core 2 Reactor pressure vessel 3 Upper dry well 4 Lower dry well 5 Wet well 6 Top head 7 Reactor well 8 Reactor well ceiling 9 Reactor building 10 Piping 11 Valves and other dynamic equipment 12 Equipment carry-in hatch 13 Air conditioning equipment Suction duct 14 Piping chamber 15 Flange 16 Catalytic recombination device 17 Catalyst 18 Water repellent coating 19 Catalyst layer 20 Catalyst holding carrier 21 Catalyst cartridge 22 Mesh-like structure 23 Air bag 24 Arc-shaped leg 25 Bowl-shaped leg 26 Caster 27 Spring-shaped leg 28 Seismic mat 30 Reactor containment vessel 31 Reinforcement concrete part 32 Liner 33 Pedestal 34 Diaphragm floor 35 Suppression pool 36 Vent passage 37, 39 Room 38 Access tunnel 40 Hood 41 Chimney 42 Opening 43 Flammable gas 44 Body 45 internal space 47 cavity 50 primary reactor coolant system piping 51 broken portion 52 ECCS pump 53 containment spray

Claims (5)

A catalyst cartridge filled with a catalyst for recombining flammable gases;
Chimney having a plurality of the catalyst cartridges disposed therein,
A catalytic recombination device for a nuclear power plant having a hood above the chimney,
A catalytic recombination apparatus, wherein a cavity is provided in the catalyst. A catalyst cartridge filled with a catalyst for recombining flammable gases;
A plurality of the catalyst cartridges disposed therein, and a chimney provided with a lower opening for allowing the combustible gas to flow into the lower part;
Above the chimney is a catalytic recombination apparatus for a nuclear power plant including a hood having an upper opening for discharging the gas after recombination to the outside,
A catalytic recombination apparatus, wherein a reticulated structure or an air bag is provided in the upper opening and the lower opening. A catalyst cartridge filled with a catalyst for recombining flammable gases;
A plurality of the catalyst cartridges disposed therein, and a chimney provided with a lower opening for allowing the combustible gas to flow into the lower part;
Above the chimney is a catalytic recombination apparatus for a nuclear power plant including a hood having an upper opening for discharging the gas after recombination to the outside,
A catalytic recombination apparatus comprising one of an arc-shaped leg, a bowl-shaped leg, a movable caster, and a spring-shaped leg. A catalytic recombination device according to claim 2 or claim 3,
A catalytic recombination apparatus, wherein a cavity is provided in the catalyst. A catalyst cartridge filled with a catalyst for recombining flammable gases;
Chimney having a plurality of the catalyst cartridges disposed therein,
A catalyst for use in a catalytic recombination device of a nuclear power plant having a hood above the chimney,
A catalyst used in a catalytic recombination apparatus, wherein a cavity is provided inside the catalyst.

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