JP7689508B2 - Hydrogen countermeasure purge system inside reactor building - Google Patents

Description

The present invention relates to a purge system for dealing with hydrogen inside a reactor building, and in particular to a purge system for dealing with hydrogen inside a reactor building that is suitable for installation in a small room inside the reactor building that has a smaller volume than the reactor pressure vessel.

In general, in a nuclear power plant, if an accident were to occur in which the reactor core located inside the reactor pressure vessel were to melt (hereafter referred to as a severe accident), hydrogen gas would be generated inside the reactor containment vessel due to a metal-water reaction, and hydrogen and oxygen gases could be generated due to the radioactive decomposition of water. The concentration of flammable gases such as hydrogen generated inside the reactor containment vessel is designed to be controlled below the flammable limit by a flammable gas concentration control system.

However, in the event of a serious accident, flammable gases such as hydrogen generated inside the reactor containment vessel may leak into a small room inside the reactor building. If a leak of flammable gases such as hydrogen were to occur in an amount far greater than expected, hydrogen would accumulate in the small room, and there is a non-zero possibility that combustion could occur.

As a measure to deal with hydrogen inside a reactor building, for example, Patent Document 1 proposes exhausting the gas using an emergency gas treatment system.

According to Patent Document 1, by activating the emergency gas treatment system, hydrogen that has leaked from the reactor containment vessel into the reactor building can be released into the outside air from the main steam stack, preventing hydrogen from burning inside the reactor building.

In addition, one method for treating hydrogen inside a reactor building is the technology described in Patent Document 2, for example.

According to Patent Document 2, by installing a catalytic recombination device inside the reactor building, the combustible gases hydrogen and oxygen generated inside the reactor containment vessel are recombined into water by the catalytic layer contained in the catalyst. As a result, the combustible gas concentration is suppressed below the flammable limit, making it possible to passively prevent the combustion of combustible gas even in the event of a total power loss.

JP 2015-232492 A JP 2011-174773 A

However, in the above-mentioned Patent Document 1, when treating hydrogen that has leaked into a small room inside a reactor building, it is necessary to indirectly vent the hydrogen inside the small room via a duct from a location away from the target small room, which poses the problem that direct hydrogen treatment is not possible.

In addition, in the above-mentioned Patent Document 2, if a catalytic recombination device is installed in a small room inside a reactor building, the temperature inside the small room is likely to rise due to the reaction heat of hydrogen combustion or recombination due to the small volume of the small room, which may have a negative impact on workers entering the room and on equipment.

The present invention has been made in consideration of the above points, and its purpose is to provide a hydrogen countermeasure purge system for use in a reactor building that can directly treat hydrogen in a small room in the reactor building, is self-sustaining and usable even in the event of a power loss, and prevents the temperature rise in the small room.

In order to achieve the above object, the present invention provides a purge system for hydrogen countermeasures in a reactor building, which comprises a reactor pressure vessel, a reactor containment vessel installed on the outer periphery of the reactor pressure vessel at a predetermined distance, and a small room which communicates with the inside of the reactor containment vessel via a penetration and has a smaller volume than the reactor pressure vessel, and which suppresses the concentration of hydrogen leaking from the reactor containment vessel to the small room,
The hydrogen countermeasure purge system includes a gas supply unit that supplies a purge gas for reducing a hydrogen concentration inside the small room, a temperature measurement unit that measures a temperature rise inside the small room, a hydrogen concentration estimation unit that estimates a hydrogen concentration inside the small room based on the temperature rise inside the small room measured by the temperature measurement unit, and an adjustment unit that adjusts the amount of the purge gas supplied by the gas supply unit in accordance with the hydrogen concentration estimated by the hydrogen concentration estimation unit, and supplies the purge gas from the gas supply unit adjusted by the adjustment unit into the small room to dilute the hydrogen concentration inside the small room in accordance with the hydrogen concentration, thereby making the hydrogen concentration inside the small room less than the flammable limit. The hydrogen countermeasure purge system comprises an air conditioner which is the gas supply unit installed inside the small room, a purge gas piping which is connected at one end to the air conditioner and which sprays the purge gas from the air conditioner into the small room from the other end, a temperature measurement and hydrogen concentration estimator which has the functions of the temperature measurement unit and the hydrogen concentration estimation unit, and an adjustment valve which is installed midway along the purge gas piping and has the function of the adjustment unit, and which is characterized in that the purge gas from the air conditioner which has been adjusted by the adjustment valve is sprayed into the small room to dilute the hydrogen concentration in the small room in accordance with the hydrogen concentration, thereby making the hydrogen concentration in the small room below the flammability limit .

According to the present invention, hydrogen treatment can be performed directly in a small room inside a reactor building, the system is self-sustaining and can be used even in the event of a power loss, and the temperature rise inside the small room can be suppressed.

1 is a cross-sectional view of the inside of a reactor building according to a first embodiment of a purge system for dealing with hydrogen inside a reactor building of the present invention; 1 is a cross-sectional view of the inside of a small room in a reactor building according to a first embodiment of a purge system for dealing with hydrogen in a reactor building of the present invention; FIG. 11 is a cross-sectional view of the inside of a small room in a reactor building according to a second embodiment of the purge system for dealing with hydrogen in a reactor building of the present invention. FIG. 11 is a cross-sectional view of the inside of a small room in a reactor building according to a third embodiment of the purge system for dealing with hydrogen in a reactor building of the present invention. FIG. 11 is a cross-sectional view of the inside of a small room in a reactor building according to a fourth embodiment of the purge system for dealing with hydrogen in a reactor building of the present invention.

The hydrogen countermeasure purge system for use in a reactor building of the present invention will be described below based on the illustrated embodiment. Note that in each embodiment, the same components are given the same reference numerals and duplicated explanations will be omitted.

The hydrogen countermeasure purge system in the reactor building according to the first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view of the inside of the reactor building 1 according to the hydrogen countermeasure purge system in the reactor building according to the first embodiment of the present invention, and Figure 2 is a cross-sectional view of the inside of the small room 5 in the reactor building 1 according to the hydrogen countermeasure purge system in the reactor building according to the first embodiment of the present invention.

As shown in FIG. 1, the reactor building 1 contains a reactor pressure vessel 2, a reactor containment vessel 3 installed at a distance from the outer periphery of the reactor pressure vessel 2, and a small room 5 with a smaller volume than the reactor pressure vessel 2 that is connected to the inside of the reactor containment vessel 3 via a penetration 4. The hydrogen countermeasure purge system in the reactor building in this embodiment is intended to suppress the concentration of hydrogen leaking from the reactor containment vessel 3 to the small room 5.

As shown in FIG. 2, the hydrogen countermeasure purge system in the reactor building in this embodiment is roughly composed of a gas cylinder 7, which is installed inside the small room 5 and serves as a gas supply unit that supplies purge gas to reduce the hydrogen concentration inside the small room 5, a purge gas pipe 10 connected to the gas cylinder 7 at one end and spraying the purge gas in the gas cylinder 7 from the other end into the small room 5, a temperature measurement and hydrogen concentration estimator 9 having the function of a temperature measurement unit that measures the temperature rise inside the small room 5 and the function of a hydrogen concentration estimation unit that estimates the hydrogen concentration inside the small room 5 based on the temperature rise inside the small room 5 measured by the temperature measurement unit, and an adjustment valve 8 installed midway through the purge gas pipe 10 and having the function of an adjustment unit that adjusts the amount of purge gas supplied by the gas cylinder 7 according to the hydrogen concentration estimated by the temperature measurement and hydrogen concentration estimator 9.

The hydrogen countermeasure purge system in the reactor building of this embodiment sprays purge gas from the gas cylinder 7, which is adjusted by the adjustment valve 8, into the small room 5, diluting the hydrogen concentration in the small room 5 according to the hydrogen concentration, thereby suppressing the hydrogen concentration in the small room 5 below the flammable limit.

The hydrogen countermeasure purge system inside the reactor building in this embodiment will be explained in detail below.

For example, in the event of a serious accident such as melting of the reactor core located in the reactor pressure vessel 2, if hydrogen generated in the reactor containment vessel 3 leaks from the penetration 4 into the small room 5 in the reactor building 1, the temperature measurement and hydrogen concentration estimator 9 will detect the temperature rise and hydrogen concentration caused by the hydrogen leakage in the small room 5.

The temperature measurement and hydrogen concentration estimator 9 may use, for example, a number of catalytic combustion sensors, some with a catalyst and some without (note that the catalyst reacts with hydrogen, and the presence of hydrogen in the small chamber 5 is detected by the reaction of the catalyst with hydrogen).

In this catalytic combustion sensor, the temperature of the sensor equipped with a catalyst rises as it reacts with hydrogen, and as the temperature of the sensor rises, the resistance value increases, causing an unbalanced current to flow between the sensor equipped with a catalyst and the sensor equipped with no catalyst. The magnitude of this unbalanced current is proportional to the hydrogen concentration below the flammable limit concentration, so the hydrogen concentration can be estimated by knowing the magnitude of the unbalanced current, and is hardly affected by environmental temperature or humidity.

The opening of the regulating valve 8 is adjusted according to the estimated hydrogen concentration using this temperature measurement and hydrogen concentration estimator 9, passively adjusting the amount of purge gas sprayed from the gas cylinder 7 via the purge gas piping 10.

The purging gas in the gas cylinder 7 may be, for example, an inert gas such as nitrogen, argon, or carbon dioxide. In addition, air may be used if consideration is given to the entry of workers into the small room 5.

In addition, the amount of purge gas ejected from the gas cylinder 7 through the purge gas piping 10 is sufficient to suppress the hydrogen concentration below the flammability limit (reduce the hydrogen concentration below the flammability limit), and the amount of purge gas ejected is adjusted according to the hydrogen concentration (for example, if the hydrogen concentration is high, the amount of purge gas ejected is increased, and if the hydrogen concentration is low, the amount of purge gas ejected is decreased), so that the hydrogen concentration in the small chamber 5 can be suppressed below the flammability limit even if hydrogen continues to leak from the reactor containment vessel 3 for a long period of time.

Although not shown, a detector installed in small room 5 detects that the hydrogen concentration in small room 5 is below the flammable limit.

The purged hydrogen is discharged from the gas cylinder 7 via the purge gas pipe 10 and discharged outside the small chamber 5 through an opening 11 in the small chamber 5 or a pipe (not shown) for processing.

In addition, even in places where hydrogen is likely to accumulate locally, such as in depressions within the small chamber 5, the hydrogen concentration can be uniformly diluted by the convection effect of the purge gas.

This allows the hydrogen concentration in the small chamber 5 to be passively kept below the flammable limit and combustion to be prevented even in the event of a power loss.

Therefore, according to this embodiment, hydrogen treatment can be performed directly in the small room 5 inside the reactor building 1, the small room 5 is self-sustaining and can be used even in the event of a power loss, and the temperature rise inside the small room 5 is suppressed.

The small rooms 5 mentioned above may be rooms such as the hatch room for carrying in equipment, the airlock room for personnel, the suppression chamber entrance room, and other rooms that have the potential for hydrogen leakage from the containment vessel, and rooms adjacent to these rooms, and the volume of these rooms is approximately 100 ^m3 or less. This is the same in each of the embodiments described below.

Figure 3 shows the inside of a small room 5 in a reactor building 1 relating to embodiment 2 of the hydrogen countermeasure purge system in a reactor building of the present invention.

Example 2 shown in FIG. 3 is a modified example of Example 1, and in this example shown in FIG. 2, the gas cylinder 7 is installed outside the small room 5, and the purge gas pipe 10 for spraying the purge gas into the small room 5 is installed to connect the outside to the inside of the small room 5. The rest of the configuration is the same as that of Example 1 in FIG. 2.

As a result, the purge gas is ejected from the gas cylinder 7 through the purge gas pipe 10 into the small chamber 5. The amount of gas ejected is adjusted according to the hydrogen concentration estimated by the temperature measurement and the hydrogen concentration estimator 9, so that the hydrogen concentration in the small chamber 5 can be kept below the flammable limit.

In addition, by installing a gas cylinder 7 outside the small room 5, if the gas in the gas cylinder 7 runs low, it is possible to supply purging gas to the small room 5 for a long period of time by switching to another gas cylinder.

The hydrogen concentration in the small chamber 5 can also be kept below the flammable limit by connecting the purge gas piping 10 to an inert gas system that can supply inert gas instead of the gas cylinder 7. This is possible because the inert gas system is outside the small chamber 5, and is not possible with the configuration of Example 1 in Figure 2.

Even with this configuration of the present embodiment, the effects are the same as those of the first embodiment.

Figure 4 shows the inside of a small room 5 in a reactor building 1 relating to embodiment 3 of the hydrogen countermeasure purge system in a reactor building of the present invention.

Example 3 shown in FIG. 4 is a modified example of Example 1. In this example shown in FIG. 4, a catalytic recombination device 13 that suppresses the reaction heat during hydrogen processing is installed in the center of the lower part inside the small chamber 5. The rest of the configuration is the same as that of Example 1 in FIG. 2.

By installing the catalytic recombination device 13 described above at the bottom inside the small chamber 5, hydrogen and oxygen are recombined by the catalytic layer contained in the catalyst to become water. In addition, the opening of the adjustment valve 8 is adjusted according to the hydrogen concentration estimated by the temperature measurement and hydrogen concentration estimator 9, and purge gas is sprayed from the gas cylinder 7 into the small chamber 5 via the purge gas piping 10.

This allows the hydrogen concentration in the small chamber 5 to be diluted, making it possible to suppress the reaction heat generated during hydrogen processing by the catalytic recombination device 13, and allowing hydrogen to be processed without adversely affecting the equipment 6 in the small chamber 5.

Furthermore, by combining purging with gas from the gas cylinder 7 and hydrogen processing using the catalytic recombination device 13, more efficient hydrogen processing is possible, and the hydrogen concentration in the small chamber 5 can be kept below the flammable limit, preventing combustion.

Even with this configuration of the present embodiment, the effects are the same as those of the first embodiment.

Figure 5 shows the inside of a small room 5 in a reactor building 1 relating to embodiment 4 of the hydrogen countermeasure purge system in a reactor building of the present invention.

Example 4 shown in Figure 5 is a modified version of Example 1. In this example shown in Figure 5, an air conditioner 12 is installed in the small room 5 instead of the gas cylinder 7, assuming that the emergency power supply is restored.

The hydrogen countermeasure purge system in the reactor building in this embodiment is similar to the configuration in Example 1 in FIG. 2 in that it includes a purge gas pipe 10 connected at one end to an air conditioner 12 and spraying purge gas from the air conditioner 12 into the small room 5 from the other end, a temperature measurement and hydrogen concentration estimator 9 having the functions of the temperature measurement unit and the hydrogen concentration estimation unit described above, and an adjustment valve 8 installed midway along the purge gas pipe 10 and having the functions of the adjustment unit described above.

The air conditioner 12 may be installed anywhere in the small room 5, but it is preferable to install it in a location that allows for good convection.

By configuring this embodiment as described above, the amount of purge gas supplied from the air conditioner 12 can be adjusted by the regulating valve 8 based on the hydrogen concentration estimated by the temperature measurement and hydrogen concentration estimator 9, and the hydrogen concentration in the small room 5 can be suppressed below the flammable limit.

In addition, in this embodiment, the gas cylinder 7 as in the above-mentioned embodiments 1-3 is not necessary, and when a power source is available, it is advisable to use the air conditioner 12 of this embodiment.

Even with this configuration of the present embodiment, the effects are the same as those of the first embodiment.

The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

1... Reactor building, 2... Reactor pressure vessel, 3... Reactor containment vessel, 4... Penetration, 5... Small room, 6... Equipment, 7... Gas cylinder, 8... Regulating valve, 9... Temperature measurement and hydrogen concentration estimator, 10... Purge gas piping, 11... Opening, 12... Air conditioner, 13... Catalytic recombination device.

Claims (6)

A hydrogen countermeasure purge system for a reactor building that contains a reactor pressure vessel, a reactor containment vessel installed on the outer periphery of the reactor pressure vessel at a predetermined interval, and a small room that communicates with the inside of the reactor containment vessel through a penetration and has a smaller volume than the reactor pressure vessel, the purge system being configured to suppress a hydrogen concentration leaked from the reactor containment vessel to the small room,
The hydrogen countermeasure purge system includes a gas supply unit that supplies a purge gas for reducing a hydrogen concentration in the small room, a temperature measurement unit that measures a temperature rise in the small room, a hydrogen concentration estimation unit that estimates a hydrogen concentration in the small room based on the temperature rise in the small room measured by the temperature measurement unit, and an adjustment unit that adjusts the amount of the purge gas supplied by the gas supply unit in accordance with the hydrogen concentration estimated by the hydrogen concentration estimation unit,
The purge gas from the gas supply unit adjusted by the adjustment unit is supplied into the small chamber to dilute the hydrogen concentration in the small chamber in accordance with the hydrogen concentration, and the hydrogen concentration in the small chamber is made to be less than the flammable limit,
The hydrogen countermeasure purge system comprises an air conditioner which is the gas supply unit installed inside the small room, a purge gas pipe which is connected to the air conditioner at one end and which sprays the purge gas from the air conditioner from the other end into the small room, a temperature measurement and hydrogen concentration estimator having the functions of the temperature measurement unit and the hydrogen concentration estimation unit, and an adjustment valve which is installed midway along the purge gas pipe and has the function of the adjustment unit,
A hydrogen countermeasure purge system in a reactor building, characterized in that the purge gas from the air conditioner regulated by the regulating valve is sprayed into the small room to dilute the hydrogen concentration in the small room in accordance with the hydrogen concentration, thereby making the hydrogen concentration in the small room below the flammability limit . A purge system for hydrogen countermeasures in a reactor building according to claim 1 ,
the temperature measurement and hydrogen concentration estimation device is a catalytic combustion sensor having a plurality of sensors, some of which include a catalyst and some of which do not include a catalyst;
The catalytic combustion sensor is a hydrogen countermeasure purge system for use in a reactor building, characterized in that the temperature of the catalytic combustion sensor rises as the sensor equipped with a catalyst reacts with hydrogen, and as the temperature of the sensor rises, its resistance value increases, causing an unbalanced current to flow between the sensor equipped with a catalyst and the sensor equipped with no catalyst, and the hydrogen concentration can be estimated by determining the magnitude of this unbalanced current. A purge system for hydrogen countermeasures in a reactor building according to claim 2 ,
A purge system for dealing with hydrogen in a reactor building, characterized in that the opening of the regulating valve is adjusted in accordance with the temperature measurement and the hydrogen concentration estimated by the hydrogen concentration estimator, and the amount of the purge gas sprayed from the air conditioner through the purge gas piping is adjusted. A purge system for hydrogen countermeasures in a reactor building according to claim 3 ,
A purge system for dealing with hydrogen in a reactor building, characterized in that if the hydrogen concentration is high, the amount of purge gas ejected is increased, and if the hydrogen concentration is low, the amount of purge gas ejected is decreased. A purge system for hydrogen countermeasures in a reactor building according to claim 4 ,
1. A purge system for hydrogen countermeasures in a reactor building, wherein the small room has an opening or a pipe for discharging purged hydrogen to the outside of the small room. A purge system for hydrogen countermeasures in a reactor building according to any one of claims 1 to 5 ,
A purge system for hydrogen countermeasures in a reactor building, wherein the small room in the reactor building is any of rooms that have the potential for hydrogen leakage from the reactor containment vessel, such as an equipment entrance hatch room, an airlock room for personnel, and a suppression chamber entrance room, or rooms adjacent to these.

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