JP6407658B2 - Reactor building and method for preventing hydrogen accumulation - Google Patents

Description

  Embodiments described herein relate generally to a nuclear reactor building and a hydrogen accumulation prevention method for preventing hydrogen detonation due to leaked hydrogen in a nuclear power plant.

  In nuclear power plants, in the unlikely event that an accident occurs in a nuclear reactor and hydrogen leaks into the nuclear reactor building, installation of a building vent device for ventilation of the nuclear reactor building is underway.

  FIG. 4 is a schematic diagram of a conventional nuclear power plant (boiling water reactor). The nuclear reactor 5 is accommodated in the nuclear reactor containment vessel 4, and the nuclear reactor containment vessel 4 is installed in the nuclear reactor building 1. Further, a hydrogen detector 3 for detecting the hydrogen concentration is provided in the reactor building 1, and a building vent device 2 is provided on the roof of the reactor building 1. Further, the reactor building 1 is also provided with an emergency gas processing system 6 including a blower 7, a filter 8 and an exhaust pipe 9.

  In such a nuclear power plant, if the primary piping such as the main steam pipe is broken in the reactor containment vessel 4, the high-temperature and high-pressure primary coolant is released, and the pressure and temperature inside the reactor containment vessel 4 are released. Will rise rapidly. Under such an event, water used as a coolant in the nuclear reactor 5 is decomposed into hydrogen and oxygen by radiation to generate hydrogen. Furthermore, when the temperature of the fuel cladding tube in the nuclear reactor 5 rises, a reaction occurs between water vapor and zirconium of the fuel cladding tube material (Metal-Water reaction), and a large amount of hydrogen is generated in a short time. .

  The hydrogen generated in this manner is discharged into the reactor containment vessel 4 together with the coolant from the fractured port of the fractured pipe, etc., increasing the hydrogen concentration and the internal pressure. When the high pressure state of the reactor containment vessel 4 continues, a gas containing hydrogen and a radioactive substance is released from the reactor containment vessel 4 to the reactor building 1.

  In such a situation, when the power source can be used, the emergency gas treatment system 6 operates, and the leaked gas containing hydrogen in the reactor building 1 is sent to the filter 8 by the blower 7, and the radioactive material is sent by the filter 8. Is removed from the exhaust tube 9 after being removed.

  In addition, when the emergency gas treatment system 6 does not operate or is delayed due to power supply loss or power supply recovery delay, the hydrogen detector 3 detects an increase in the hydrogen concentration in the reactor building 1 and vents the building. By opening the apparatus 2, the hydrogen in the reactor building 1 is released into the atmosphere.

  However, when hydrogen exhaust by the building vent device 2 is not sufficient, hydrogen leaked into the reactor building 1 is mixed with oxygen in the atmosphere, and hydrogen detonation is performed when the hydrogen concentration exceeds 12.5-17 vol%. It can happen.

  Therefore, in the event of an accident, an inert gas is injected into the reactor building to dilute hydrogen, and the building vent device to the outside air provided on the ceiling of the reactor building is opened to release leaked gas containing hydrogen to the outside. To prevent hydrogen detonation (Patent Document 1), and in order to remove hydrogen in the reactor building when power is lost, a static catalytic combustible gas treatment device in each room in the reactor building A means (Patent Document 2) for installing the device has been proposed.

  Furthermore, utilizing the property that leaked gas containing hydrogen tends to move upward due to the density difference from the surrounding air, a catalytic combustible gas is connected to a communication port such as a hatch provided between the floors of the reactor building. A means for removing hydrogen leaked into the reactor building 1 by installing a treatment apparatus has been proposed (Patent Document 3).

JP 2012-225823 A JP 2009-69121 A JP2013-246098A

  By the way, the reactor building 1 has a plurality of floors 10 on which various devices, pipes and the like are arranged. For example, when hydrogen leaks in the lower floor 10 of the reactor building, a leaking gas 18 containing hydrogen ( Hereinafter, the “leaked hydrogen gas”) has a lower density than the air in the reactor building, and thus easily moves to the upper space of the floor 10.

  For example, as shown in FIG. 5A, assuming that a device 20 that may release leaked hydrogen gas such as piping and valves is installed on the floor 10 and hydrogen leaks from the device 20, the device 20 The leaked hydrogen gas 18 released from 20 moves to the upper space directly above, moves along the ceiling portion 11 of the floor 10, and passes through the communication port 15 such as a device hatch provided in the ceiling portion 11. Will move to the next floor 10.

  However, for example, as shown in FIG. 5B, when an obstacle 12 such as a beam protrudes from the ceiling portion 11 of the floor 10 on which the device 20 that may release leaked hydrogen gas is installed, There is a possibility that leaked hydrogen gas 18 accumulates in a region partitioned by the obstacle 12 and a leaked hydrogen gas accumulation region 16 having a locally high hydrogen concentration is formed.

  In this case, even if a catalytic combustible gas treatment device is installed in the communication port 15 with the upper floor 10, the leaked hydrogen gas accumulation region is reached before the leaked hydrogen gas 18 reaches the combustible gas treatment device. 16 has a problem that hydrogen detonation may occur.

  On the other hand, in order to prevent the leaked hydrogen gas 18 from accumulating on the ceiling portion 11 of the floor 10, it is conceivable to increase the installation locations of the communication ports 15 or to install a panel or the like covering the obstacle 12 on the ceiling. In addition to requiring large-scale construction, construction may be difficult due to maintenance of the strength of the reactor building 1 and interference with other structures.

  The present invention has been made to solve the above problems, and prevents leakage hydrogen gas from accumulating even when obstacles such as beams are installed on the ceiling of the floor of the reactor building. An object of the present invention is to provide a reactor building capable of suppressing hydrogen detonation and a method for preventing hydrogen accumulation.

In order to solve the above-described problem, a reactor building according to an embodiment of the present invention is installed by projecting from a plurality of floors and a ceiling portion of at least one of the plurality of floors toward the inside of the floor. A plurality of obstacles, a communication port installed in the ceiling portion of the floor where the plurality of obstacles are installed, and a region partitioned by the obstacles, wherein the plurality of obstacles are installed A leaked hydrogen gas storage region in which leaked hydrogen gas from the equipment in the floor is stored, a lower end surface of the leaked hydrogen gas storage region or a suction port of the leaked hydrogen gas located above the lower end surface , catalyst to couple the leaked hydrogen gas has flowed from the suction port with oxygen discharge port for discharging the gas after being recombined processed by the catalyst is disposed inside of the leaked hydrogen gas accumulation region, the Hydrogen recombiner which, characterized by comprising a.

  According to the embodiment of the present invention, it is possible to prevent leaked hydrogen gas from accumulating on the ceiling of the floor of the reactor building.

The schematic diagram of a nuclear reactor building provided with the hydrogen accumulation prevention system which concerns on embodiment of this invention. The schematic diagram which shows the effect of a reactor building provided with the hydrogen accumulation prevention system which concerns on embodiment of this invention. The schematic diagram of a catalytic hydrogen recombiner. Schematic diagram of a conventional nuclear power plant. (A) is a figure which shows the behavior of leaking hydrogen gas when there is no obstacle in a floor ceiling part, (b) is a figure which shows the behavior of leaking hydrogen gas when there is an obstacle.

  Hereinafter, embodiments of a reactor building and a method for preventing hydrogen accumulation thereof according to the present invention will be described with reference to the drawings.

  In addition, as shown in FIG. 1, the hydrogen accumulation prevention system for a reactor building according to the present embodiment is installed such that obstacles such as beams, partition walls, partition plates, etc. protrude from the ceiling into the floor. Applied to a floor on which equipment (through holes, piping, valves, pumps, etc.) that may release leaked hydrogen gas is installed.

(Constitution)
In the present embodiment, as shown in FIG. 1, a plurality of obstacles 12 a to 12 c are installed on the ceiling portion 11 of the floor 10 of the reactor building 1 so as to protrude from the ceiling portion 11 toward the interior of the floor. A device 20 (through hole, piping, valve, pump, etc.) that may release leaked hydrogen gas is installed inside the floor 10, and the upper floor is located on the ceiling 11 of the floor 10. A communication port 15 made of a hatch or the like communicating with 10 is provided.

In the present embodiment, an example will be described in which there are three obstacles 12a to 12c, of which the obstacle 12b has the largest protruding height.
Here, if the ceiling portion 11a immediately above the device 20 is the upstream and the communication port 15 is the downstream, the leaked hydrogen gas 18 released from the device 20 at the time of the accident is caused by the obstacles 12a to 12c between the upstream and the downstream. It accumulates in partitioned areas (hereinafter referred to as “leaked hydrogen gas accumulation areas”) 16a-1 and 16b-1.

  In the present embodiment, for example, a catalytic hydrogen recombiner 13 is installed in the leaked hydrogen gas accumulation regions 16a-1 and 16b-1. At that time, when the protruding height of the obstacle 12a upstream of the leaked hydrogen gas accumulation region 16a-1 is lower than the protruding height of the obstacle 12b downstream, the baffle plate 14 is extended to the tip of the obstacle 12a. However, the leakage hydrogen gas 18 is smoothly transferred from upstream to downstream (communication port 15) by setting the height to be equal to or higher than the protruding height of the obstacle 12b.

  In this way, when the protruding heights of the plurality of obstacles 12 (12a to 12c) are different from each other, the baffle plate 14 is appropriately set so that the protruding heights of the obstacles 12 gradually decrease from the upstream toward the downstream. Extend to the tip of the obstacle 12.

  In the example of FIG. 1, the example in which the baffle plate 14 is extended at the tip of the obstacle 12 a has been described. However, the present invention is not limited to this, and the protrusion height depends on the protrusion height of each of the plurality of obstacles 12. A baffle plate is extended at the tip of an obstacle that needs to be increased. Therefore, there are cases where it is not necessary to provide the baffle plate 14, for example, when the protruding height of each of the plurality of obstacles 12 decreases sequentially from upstream to downstream.

  As the hydrogen recombiner 13, for example, as shown in FIG. 3, a structure constituted by a housing 112 that contains a catalyst 111 and is provided with a discharge port 113 a and a suction port 113 b can be adopted. In this case, the leaked hydrogen gas 18 flows in from the suction port 113b, is combined with oxygen by the catalyst 111, generates water vapor, and is discharged from the discharge port 113a.

  In the present embodiment, the hydrogen recombiner 13 has an inlet 113b whose inner side is a lower end surface (dashed lines a and b in FIG. 1) of the leaked hydrogen gas accumulation regions 16a-1 and 16b-1 or lower end surface (ceiling portion). Side). The hydrogen recombiner 13 of FIG. 3 is shown with the suction port 113b on the lower side and the discharge port 113a on the upper side, but the hydrogen recombiner 13 is installed in the leaked hydrogen gas accumulation regions 16a-1 and 16b-1. In doing so, the inlet 113b does not necessarily have to be on the lower side (inside the floor). That is, in the present embodiment, the suction port 113b is arranged on the lower end surface (broken lines a and b in FIG. 1) of the leaked hydrogen gas accumulation regions 16a-1 and 16b-1 or on the inner side (ceiling side) than the lower end surface. As long as it is sufficient, the hydrogen recombiner 13 of FIG. 3 can be placed sideways, or the suction port 113b can be on the upper side (ceiling side). In particular, when the suction port of the hydrogen recombiner 13 is set to the upper side (ceiling side), the suction port of the hydrogen recombiner 13 is made to coincide with the lower end surfaces of the leaked hydrogen gas accumulation regions 16a-1 and 16b-1. You may arrange | position so that substantially all of the hydrogen recombiners 13 including the exit 113a may become below (floor inner side) from the lower end surface of leaking hydrogen gas storage area | region 16a-1, 16b-1. In this case, the leaked hydrogen gas in the leaked hydrogen gas accumulation regions 16a-1 and 16b-1 can be efficiently processed by the flow of the leaked hydrogen gas in the leaked hydrogen gas accumulation regions 16a-1 and 16b-1. it can.

In this embodiment, an example in which one hydrogen recombiner 13 is provided in each of the leaked hydrogen gas accumulation regions 16a-1 and 16b-1 is described. However, the present invention is not limited to this and can be assumed. A plurality of hydrogen recombiners 13 may be provided according to the amount of accumulation.
The hydrogen recombiner 13 may be fixedly supported on the obstacles 12a to 12c or the wall surface of the floor 10, or may be supported by being suspended from the ceiling portion 11.

(Function)
In the hydrogen accumulation prevention system configured as described above, when the leaked hydrogen gas 18 is released from the device 20, it rises toward the ceiling portion 11 due to the density difference from the surrounding air, and leaks hydrogen along the ceiling portion 11. It moves downstream (communication port 15) through the gas accumulation regions 16a-1 and 16b-1.

  At this time, part of the leaked hydrogen gas 18 is gradually accumulated in the leaked hydrogen gas accumulation regions 16a-1 and 16b-1, and the accumulated leaked hydrogen gas 18 is combined with oxygen by the hydrogen recombiner 13. The hydrogen concentration decreases. The low hydrogen concentration gas heated by the recombination reaction heat has a higher temperature and a lower density than the surrounding air, so it is stratified in the vicinity of the ceiling 11 to form stratified regions 16a-2 and 16b-2. (See FIG. 2).

  The stratified regions 16a-2 and 16b-2 prevent the leaked hydrogen gas 18 released from the device 20 from entering the region. The leaked hydrogen gas 18 that has been prevented from entering is prevented from moving upstream by the baffle plate 14 upstream of the leaked gas accumulation region 16a-1, so that the stratified regions 16a-2 and 16b-2 are passed through. After that, the transition is made smoothly to the downstream side, and the transition is made from the communication port 15 to the upper floor 10 to be diffusion diluted.

  At that time, since the hydrogen recombiner 13 is arranged in the vicinity of the inside of the lower end surfaces a and b of the leakage gas accumulation regions 16a-1 and 16b-1, it accumulates in the leakage gas accumulation regions 16a-1 and 16b-1. The leaked hydrogen gas 18 can be efficiently removed, and the stratified regions 16a-2 and 16b-2 can be formed over the entire region. Thereby, it is possible to efficiently prevent the hydrogen leakage gas 18 from entering the region.

(effect)
As described above, according to the present embodiment, when the leaked hydrogen gas accumulation regions 16a-1 and 16b-1 are formed on the ceiling 11 of the reactor building 1 by the obstacle 12 such as a beam, the leakage occurs. By installing the hydrogen recombiner 13 in the hydrogen gas accumulation region, the hydrogen gas accumulated in the region is removed and the stratified regions 16a-2 and 16b-2 are formed, so that the leaked hydrogen gas 18 Invasion and accumulation of hydrogen can be prevented, thereby preventing the occurrence of hydrogen detonation.

  Further, by providing the hydrogen recombiner 13 in the vicinity of the upper part of the lower end surfaces of the leaked hydrogen gas accumulation regions 16a-1 and 16b-1, leaked hydrogen accumulated in the leaked hydrogen gas accumulation regions 16a-1 and 16b-1 The gas 18 can be efficiently removed, and the stratified regions 16a-2 and 16b-2 can be formed over the entire region.

Furthermore, when the protrusion heights of the plurality of obstacles 12 (12 a to 12 c) are different, the protrusion height of the obstacle 12 from the leaked hydrogen gas accumulation region 16 a-1 formed immediately above the device 20 toward the communication port 15. The leakage hydrogen gas 18 can be smoothly transferred from the upstream side to the communication port 15 by extending the baffle plate 14 for adjusting the protrusion height to the necessary obstacle 12 so that the height of the obstacle is gradually reduced.
Thereby, hydrogen detonation in the ceiling part 11 of the floor 10 can be suppressed only by simple incidental construction without requiring large-scale construction.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, combinations, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Reactor building, 2 ... Building vent device, 3 ... Hydrogen detector, 4 ... Reactor containment vessel, 5 ... Reactor, 6 ... Emergency gas processing system, 7 ... Blower, 8 ... Filter, 9 ... Exhaust pipe DESCRIPTION OF SYMBOLS 10 ... Floor, 11, 11a ... Ceiling part, 12, 12a-12c ... Obstacle, 13 ... Hydrogen recombiner, 14 ... Baffle plate, 15 ... Communication port, 16a-1, 16b-1 ... Leaked hydrogen gas accumulation Region, 16a-2, 16b-2 ... Stratified region, 18 ... Leaked hydrogen gas, 20 ... Equipment

Claims (5)

Multiple floors,
A plurality of obstacles installed so as to protrude from the ceiling of at least one of the plurality of floors toward the inside of the floor;
A communication port installed in the ceiling portion of the floor where the plurality of obstacles are installed;
Leaked hydrogen gas accumulation area in which the leaked hydrogen gas from the equipment in the floor where the plurality of obstacles are installed is accumulated by the obstacle.
A lower end surface of the leaked hydrogen gas accumulation region or a suction port for leaked hydrogen gas located above the lower end surface , a catalyst for combining leaked hydrogen gas flowing in from the suction port with oxygen, a leaked hydrogen gas accumulation region And a hydrogen recombiner having an exhaust port that is disposed inside and discharges the gas after being recombined by the catalyst .   The reactor building according to claim 1, wherein the hydrogen recombiner is installed at least in a leaked hydrogen gas accumulation region formed immediately above the equipment.   The reactor building according to claim 1 or 2, wherein at least one hydrogen recombiner is installed in each of a plurality of leaked hydrogen gas accumulation regions formed from directly above the equipment toward the communication port. Multiple floors,
A plurality of obstacles installed so as to protrude from the ceiling of at least one of the plurality of floors toward the inside of the floor;
A communication port installed in the ceiling portion of the floor where the plurality of obstacles are installed;
Leaked hydrogen gas accumulation area in which the leaked hydrogen gas from the equipment in the floor where the plurality of obstacles are installed is accumulated by the obstacle.
A hydrogen recombiner having a lower end surface of the leaked hydrogen gas accumulation region or a suction port for leaked hydrogen gas located above the lower end surface;
The protruding heights of the obstacles are reduced so that the protruding heights of the plurality of obstacles gradually decrease from the leaked hydrogen gas accumulation region formed immediately above the device toward the communication port. features and to RuHara reactor building that was adjustable by baffles extending in part. In the method for preventing hydrogen accumulation in a reactor building according to any one of claims 1 to 4,
A method for preventing hydrogen accumulation in a reactor building, wherein hydrogen is recombined by the hydrogen recombiner.

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