JP5913073B2 - Reactor building hydrogen removal equipment - Google Patents

Description

  The present invention relates to a reactor building hydrogen removal facility, and more particularly to a reactor building hydrogen removal facility for removing hydrogen leaked out of a reactor containment vessel.

  Conventionally, hydrogen removal equipment for removing hydrogen generated in a containment vessel at the time of a severe accident exceeding a design standard accident is known. Such hydrogen removal facilities include a combustible gas treatment facility that mainly uses a catalyst that promotes recombination of hydrogen gas and oxygen gas, and a catalytic hydrogen removal device that promotes hydrogen recombination using static equipment.

  Of these, the combustible gas treatment equipment introduces the atmosphere inside the containment vessel to a recombination device that reacts with hydrogen and oxygen, and then recirculates it to the reactor containment vessel after recombination (hereinafter referred to as FCS). Called). The FCS is composed of a combustible gas concentration controller, which is a main body, and piping and equipment connected thereto. An example of a combustible gas treatment facility is described in Patent Document 1.

  The static catalytic hydrogen removal device is installed in the reactor containment vessel. Using the circulating flow in the containment vessel formed by the reaction heat of the combustible gas, the material that suppresses the reaction of the catalyst is captured and removed, the combustible gas is efficiently processed, and hydrogen combustion To maintain the integrity of the containment vessel. An example of a static catalytic hydrogen removal apparatus is described in Patent Document 2.

  Patent Document 3 is known to reduce the hydrogen concentration inside the reactor containment vessel by extracting only hydrogen from the atmosphere using a hydrogen permeable membrane and discharging it to the outside of the containment vessel. Yes.

JP-A-1-32198 Japanese Patent Laid-Open No. 11-94992 JP 2000-75079 A

  The techniques described in the above patent documents all assume that the generated hydrogen is present in the reactor containment vessel. It is assumed that hydrogen gas is generated in the reactor containment vessel at the time of a severe accident. For this reason, hydrogen gas is discharged from the reactor containment vessel or actively burned to remove hydrogen from the atmosphere gas in the reactor containment vessel, and the inside of the reactor containment vessel reaches the flammable limit. I try not to squeeze it.

  On the other hand, in the present invention, it is assumed that hydrogen generated in the reactor containment vessel at the time of a severe accident leaks into the reactor building and an external power source is lost. In such a state, the hydrogen leaking into the reactor building cannot be removed by the technique of the above-described patent document that performs the hydrogen treatment in the reactor containment vessel. In addition, since the external power supply is lost, measures using electric equipment are limited.

  In this regard, for example, in Patent Document 1, the atmosphere in the reactor containment vessel is guided to a recombination device that reacts hydrogen and oxygen, and then recirculated to the reactor containment vessel after recombination to prevent hydrogen combustion. However, in order to further improve the safety against hydrogen combustion, a measure to selectively remove hydrogen outside the containment vessel even when the external power supply is lost is desired.

  However, conventionally, it is not assumed that hydrogen stays near the ceiling of the reactor building due to leakage from the reactor containment vessel, and no special measures are taken when it stays. If stagnation occurs in this state, hydrogen combustion may occur near the reactor building ceiling.

  For this reason, it becomes a new subject to remove the hydrogen accumulated near the reactor building ceiling. It is necessary to suppress the release of radioactive materials released into the reactor building to the environment and to keep the hydrogen concentration below the flammable limit. Furthermore, it is necessary to have equipment for selectively removing hydrogen even when the external power supply is lost.

  In view of the above, an object of the present invention is to prevent the hydrogen concentration staying in the vicinity of the ceiling of the reactor building in a severe accident from causing the hydrogen concentration to reach the flammable limit even when the external power supply is lost.

  From the above, in the present invention, hydrogen gas generated in the reactor pressure vessel at the time of a severe accident at a nuclear power plant and staying near the ceiling of the reactor building through the reactor containment vessel is installed on the ceiling of the reactor building. It is characterized by being discharged to the outside of the reactor building through the hydrogen removal equipment.

  Here, the hydrogen removal equipment installed on the ceiling of the reactor building is a hydrogen permeable membrane that does not allow permeation of hydrogen but permeation of radioactive materials.

  The hydrogen removal equipment installed on the ceiling of the reactor building consists of an open / close ceiling that opens and closes part of the reactor building ceiling, a hydrogen concentration measuring device installed near the open / closed ceiling, an open / close ceiling and a hydrogen concentration measuring device. And a storage battery system that enables operation of the remote operation system.

  The hydrogen removal equipment of the reactor building of the present invention can be opened and closed on both sides of the hydrogen permeable membrane attached to the ceiling before the hydrogen concentration reaches the flammable limit with respect to the hydrogen remaining on the ceiling of the reactor building at the time of severe accident The automatic opening and closing ceiling effectively releases hydrogen to the outside, and has the effect of preventing hydrogen combustion in the reactor building.

Sectional drawing which shows the whole structure of the reactor building provided with the reactor building hydrogen removal equipment which concerns on 1st Example of this invention. The figure which shows the external appearance of the nuclear reactor building of FIG. Sectional drawing which shows the whole reactor building structure provided with the reactor building hydrogen removal equipment which concerns on 2nd Example of this invention. The figure which shows the external appearance of the nuclear reactor building of FIG. Sectional drawing which shows the whole structure of the reactor building provided with the reactor building hydrogen removal equipment which concerns on 3rd Example of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is a reactor building equipped with a reactor building hydrogen removal facility. Here, the reactor building hydrogen removal equipment is a hydrogen permeable membrane installed near the ceiling in the first embodiment, and is an open / close ceiling in the second and third embodiments.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing the overall structure of a reactor building equipped with a reactor building hydrogen removal facility according to a first embodiment of the present invention. FIG. 2 is a view showing an appearance of the reactor building of FIG. In the first embodiment, an example of a hydrogen permeable membrane installed on the ceiling as a reactor building hydrogen removal facility is shown.

  As shown in FIG. 1, a reactor containment vessel 4 is installed in the reactor building 1, and a reactor pressure vessel 3 is housed inside the reactor containment vessel 4. Hydrogen gas is generated in the reactor pressure vessel 3 due to a water-metal reaction by zirconium or radiolysis of water in a severe accident at a nuclear power plant. The generated hydrogen gas diffuses into the reactor containment vessel 4.

  Conventionally, on the premise that the hydrogen gas stays in the reactor containment vessel 4, the atmospheric gas in the reactor containment vessel 4 is discharged by discharging the hydrogen gas outside the reactor containment vessel 4 or by actively burning the gas. Measures are taken to remove hydrogen from the reactor containment vessel 4 so as not to reach the flammable limit.

  In the present invention, hydrogen gas in the reactor containment vessel 4 leaks to the reactor building 2 due to a severe accident, and the hydrogen gas rises toward the upper part of the building due to the density difference with air, and the ceiling of the reactor building 2 It is assumed to stay in the vicinity. If a large amount of hydrogen gas stays near the ceiling in this way reaches the flammable limit, hydrogen explosion may cause hydrogen explosion. If a hydrogen explosion is caused, the reactor building 2 itself may be destroyed. Therefore, prevention of hydrogen combustion is important from the viewpoint of confinement of radioactive materials.

  Due to the circumstances described above, hydrogen generated in the reactor pressure vessel 3 at the time of a severe accident exceeding the design standard accident stays near the ceiling of the reactor building 1 via the reactor containment vessel 4. If the concentration of hydrogen staying on the ceiling exceeds the flammability limit, there is a risk of causing hydrogen combustion, so it is necessary to release hydrogen to the outside of the reactor building 1.

  In the first embodiment of the present invention, the hydrogen permeable membrane 2 is installed on the ceiling of the reactor building 1. Only hydrogen gas 21 is selectively released from the hydrogen permeable membrane 2 on the ceiling of the reactor building 1 to the outdoor part of the hydrogen gas containing the radioactive material staying near the ceiling of the reactor building 1, but the radioactive material is hydrogen. It does not pass through the permeable membrane 2. For this reason, the confinement effect of the radioactive substance in the reactor building 1 can be expected. In the first embodiment of the present invention, since only a hydrogen permeable membrane is installed on the ceiling of the reactor building 1, various types of nuclear power generation (MarkI type and MarkII type of boiling water reactor, ABWR, Can also be applied to pressurized water reactors.

  Specifically, the hydrogen permeable membrane 2 applicable to the first embodiment of the present invention is preferably configured as follows. First, the material of the hydrogen permeable membrane is mainly divided into three types of materials, metal, polymer, and ceramic, and a hydrogen permeable membrane made of these materials is formed and installed.

  Among these, the hydrogen permeable film of the metal film is a film made of metal, and the main component is roughly divided into three kinds of films of palladium, niobium, and vanadium. Niobium and vanadium membranes have a thin palladium layer on the surface to dissociate and recombine hydrogen separation. The characteristics of the metal film are that the metal palladium adsorbs hydrogen gas, the adsorbed hydrogen dissociates, the hydrogen atoms generated by the dissociation dissolve in the palladium, the hydrogen atoms move through the film, and the hydrogen atoms are Rejoin. Niobium and vanadium can permeate hydrogen atoms well, but the amount of hydrogen dissolved is high and they tend to become brittle, so other metals such as titanium and nickel are added. A metal film is suitable for a hydrogen permeable film because its operating temperature is as high as several hundred degrees, it has excellent heat resistance, and the hydrogen permeation rate is high.

  The polymer membrane includes a membrane composed mainly of polyimide, polysulfone and silicon rubber. The polymer membrane has a two-layer structure of a separation layer (dense layer) and a support layer. Gas molecules dissolve in the separation layer and permeate the membrane. Since the component is an organic polymer, the operating temperature is as low as 150 ° C. or lower, but the hydrogen permeation rate is very high compared to other permeable membranes, so that the equipment volume can be reduced.

  The ceramic film is a film made of ceramic, and the main component is made of silicon nitride and silica. The ceramic membrane has a two-layer structure of a separation layer (dense layer) and a support layer, and gas molecules diffuse through the separation layer and permeate the membrane. Since the material is ceramic, it can be used even in a high temperature environment of about 800 ° C. However, since the hydrogen permeation flow rate is lower than other membranes, the equipment capacity may increase.

  Since the area of the hydrogen permeable membrane installed on the ceiling of the reactor building 1 varies depending on the material of the hydrogen permeable membrane, the equipment on the ceiling of the reactor building 1 is also designed according to the area of the hydrogen permeable membrane.

  Further, the hydrogen permeable membrane used in the first embodiment functions in a passive state where there is no power source, and here, hydrogen separation is performed in contact with a gas. In this case, since the inside of the reactor building 1 has increased from a normal negative pressure to a positive pressure due to the occurrence of a severe accident, it can be expected that membrane permeation is promoted by the positive pressure. However, the specific value of the pressure inside the building after a severe accident varies depending on the type of accident and changes over time, but it is thought that the building is at a positive pressure at least when the pressure inside the containment vessel rises. . In addition, the permeability of each of the above-mentioned various permeable membranes varies depending on the thickness of the membrane, temperature conditions, etc. in addition to pressure. Yes.

  FIG. 2 is a view showing the appearance of the reactor building of FIG. 1, and shows the arrangement relationship between the reactor building 1 and the hydrogen permeable membrane 2. The hydrogen gas 21 that does not contain radioactive material that has passed through the hydrogen permeable membrane 2 is released from the building to the atmosphere.

  By adopting the structure of the first embodiment as described above, the present invention can be expected to have the following functions and effects.

  By releasing only hydrogen gas from the hydrogen permeable membrane 2 to the outside of the reactor building 1 before the hydrogen concentration reaches the flammable limit in a severe accident, there is an effect of preventing hydrogen combustion in the reactor building 1 in advance. .

  By installing the hydrogen permeable membrane 2 on the ceiling of the reactor building 1, the hydrogen generated in the reactor building 1 is selectively released to prevent hydrogen combustion and to confine radioactive materials inside the reactor building 1. I can expect.

  Since this facility does not require an external power source, hydrogen can be released outside the reactor building 1 even when the external power source is lost. Furthermore, since this equipment is a static safety equipment with a hydrogen permeable membrane 2 installed on the ceiling of the reactor building 1, no operator operation is required during severe accidents.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a cross-sectional view showing the overall structure of a reactor building equipped with a reactor building hydrogen removal facility according to a second embodiment of the present invention. FIG. 4 is a view showing the appearance of the reactor building of FIG. In the second embodiment, an example of an open / close ceiling installed on the ceiling as a reactor building hydrogen removal facility will be described.

  As shown in FIG. 3, an automatic opening / closing ceiling 5 and a hydrogen concentration measuring device 6 are provided near the ceiling of the reactor building 1. The automatic opening / closing ceiling 5 and the hydrogen concentration measuring device 6 are provided with a remote operation system 8. A storage battery system 7 is provided as a system for supplying power to the automatic opening / closing ceiling 5, the hydrogen concentration measuring device 6, and the remote control system 8.

  In FIG. 3, the automatic opening / closing ceiling 5 is built in the ceiling of the reactor building 1, and the opening / closing door is closed during normal operation, and can be opened and closed by the remote control system 8 as necessary. It has become. A remote control system 8 is connected to the automatic opening / closing ceiling 5, and the operator monitors the hydrogen concentration measurement value near the ceiling with the hydrogen concentration measuring device 6, and then automatically opens and closes the ceiling from the remote control system 8. Is possible. The automatic opening / closing ceiling 5 is preferably designed so that it can be opened / closed manually by an operator in consideration of the possibility of some trouble occurring in the storage battery system 7.

  The hydrogen concentration measuring device 6 installed near the ceiling of the reactor building 1 is a device capable of measuring about 4%, which is the flammability limit of hydrogen, and measures the hydrogen concentration in the atmosphere near the ceiling of the reactor building 1 it can.

  The storage battery system 7 is attached to the automatic open / close ceiling 5 that requires power, the hydrogen concentration measuring device 6, and the remote control system 8 assuming the loss of the external power supply. The system can be operated even when the AC power is lost. Design. The storage battery of the storage battery system 7 is provided in a service building outside the reactor building 1 assuming that access to the reactor building 1 is restricted in a severe accident. It is assumed that the equipment and support structure of the storage battery system 7 have a high earthquake resistance structure and are multiplexed.

  The remote control system 8 is provided in a central control room and seismic isolation important buildings provided in buildings other than the reactor building 1. The remote operation system 8 is basically operated from the central control room, but if the central control room cannot be used, it is operated from the seismic isolated building. A hydrogen concentration measuring device 6 is connected to the remote control system 8, and the hydrogen concentration can be measured near the ceiling of the reactor building 1 and monitored in the central control room or the seismic isolated building. The remote control system 8 is connected to the left and right doors of the automatic opening / closing ceiling 5 and is designed to be able to open and close the door on one side.

  Regarding the operating conditions for opening the ceiling, here it is better to open it when the hydrogen concentration flammability limit is 4% or more and the oxygen concentration is 5% or more. Conventionally, the oxygen concentration of 5% or more is set as the operating condition because the oxygen concentration is kept at 5% or less because it corresponds to the inside of the containment vessel. However, since the present invention is a building, the hydrogen concentration lower limit of 4% or more is required. It is good to do.

  Using the above equipment, the operator monitors the hydrogen concentration detected by the hydrogen concentration measuring device 6 from the central control room or important seismic isolation building, and automatically opens and closes by the remote control system 8 before the hydrogen concentration reaches the flammable limit. The ceiling 5 is operated, and hydrogen gas 22 containing a radioactive substance is discharged from the upper ceiling of the reactor building 1 to the outside.

  Since this equipment is installed on the reactor building 1 and outside the reactor building 1, it can be applied to boiling water reactors as well as Mark I, Mark II, and ABWR, as well as pressurized water reactors. .

  FIG. 4 is a diagram showing the external appearance of the reactor building of FIG. 1, and shows how hydrogen gas containing a radioactive substance is released into the atmosphere by opening the automatic opening / closing ceiling 5.

  In the second embodiment of the present invention, the following functions and effects can be expected by using the structure of the reactor building 1 as described above.

  By operating the remote control system 8 before the hydrogen concentration reaches the flammable limit in a severe accident and releasing hydrogen to the outside of the reactor building 1, it is possible to prevent hydrogen combustion in the reactor building 1 in advance. is there. In this case, the hydrogen gas 22 containing the radioactive substance is released into the atmosphere, but a large amount of radioactive substance existing inside the reactor containment vessel 4 or inside the reactor pressure vessel 3 is released to the outside by hydrogen combustion. Can prevent the worst situation to be done in advance.

  The power source employs the storage battery system 7 and can be used even when the external power source is lost. In addition, the storage battery is installed in the service building outside the reactor building 1 to mitigate the influence of the power supply on environmental conditions during severe accidents, tsunamis, and flooding. In addition, the equipment and supporting structure shall be highly earthquake resistant and multiplexed.

  In the automatic opening and closing of the ceiling door, the remote control system 8 can be used to enable operation from the central control room and the seismic isolation important building. I can expect.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the overall structure of a reactor building equipped with a reactor building hydrogen removal facility according to a third embodiment of the present invention.

  The third embodiment of the present invention combines the function of the hydrogen permeable membrane that separates the hydrogen gas and radioactive material of the first embodiment with the hydrogen gas outdoor discharge mechanism of the second embodiment. The third embodiment also shows an example of an open / close ceiling installed on the ceiling as a reactor building hydrogen removal facility.

  In FIG. 5, the hydrogen gas outdoor release mechanism of the second embodiment is installed on the ceiling (roof) of the reactor building 1, and the hydrogen permeable membrane 2 for separating the hydrogen gas and the radioactive material of the first embodiment is shown. The function is installed on the floor 11 of the top floor 10 of the reactor building 1. The floor 11 of the top floor 10 is located above the reactor containment vessel 4.

  According to this method, hydrogen gas containing radioactive material leaked from the reactor containment vessel 4 stays in the lower part of the floor 11 of the top floor 10 (above the reactor containment vessel 4), and the hydrogen permeable membrane 2 It is separated into radioactive material and hydrogen gas by function. Since the radioactive material does not permeate the hydrogen permeable membrane 2, it stays in the space that forms the lower part of the floor 11 of the top floor 10, and only the hydrogen gas 21 permeates the top floor 10 and rises further to the ceiling of the reactor building 1 ( Stays near the roof.

  The hydrogen gas staying in the vicinity of the ceiling (roof) of the reactor building 1 is released into the atmosphere by the operation of the operator, as in the second embodiment of the present invention.

  According to the third embodiment of the present invention, the effects of the first embodiment and the effects of the second embodiment can be obtained.

1: Reactor building 2: Hydrogen permeable membrane 3: Reactor pressure vessel 4: Reactor containment vessel 5: Automatic open / close ceiling 6: Hydrogen concentration measuring device 7: Storage battery system 8: Remote control system 21: Hydrogen containing no radioactive substances Gas 22: Hydrogen gas containing radioactive material

Claims (4)

Hydrogen gas generated in the reactor pressure vessel during a severe accident at a nuclear power plant and staying near the ceiling of the reactor building through the containment vessel is passed through the hydrogen removal equipment installed on the ceiling of the reactor building. While releasing to the outdoors ,
The upper part of the room for storing the reactor containment vessel reaches the ceiling of the reactor building through the second ceiling, and the second ceiling is provided with a hydrogen permeable membrane that does not allow permeation of hydrogen and permeation of radioactive substances. reactor building of the hydrogen removal system, characterized in that it comprises. In the hydrogen removal equipment for a reactor building according to claim 1,
The hydrogen removal equipment for a reactor building, wherein the hydrogen removal equipment installed on the ceiling of the reactor building is a hydrogen permeable membrane that allows hydrogen to permeate and does not permeate radioactive materials. In the hydrogen removal equipment for a reactor building according to claim 1,
The hydrogen removal equipment installed on the ceiling of the reactor building includes an open / close ceiling in which a part of the reactor building ceiling is opened / closed, a hydrogen concentration measuring device attached in the vicinity of the open / close ceiling, the open / close ceiling, A hydrogen removal equipment for a nuclear reactor building comprising a remote control system connected to a hydrogen concentration measuring device and a storage battery system that enables the remote control system to operate. In the hydrogen removal equipment for a reactor building according to claim 3 ,
The remote control system is installed in both a central control room and a seismic isolation important building installed separately from the reactor building, and opens and closes the open / close ceiling of the reactor building. Hydrogen removal equipment in the building.

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