JP7285201B2 - Hydrogen treatment system - Google Patents

Description

TECHNICAL FIELD The present invention relates to technology of a hydrogen treatment system provided in a nuclear reactor containment vessel.

Although it is an extremely rare case, a loss-of-coolant accident such as a main steam line rupture accident and a situation in which the function of injecting water into the reactor pressure vessel by the emergency core cooling system is lost can occur at the same time. When such a situation occurs, the cooling water boils due to the decay heat generated from the fuel loaded in the reactor core (core fuel), thereby gradually lowering the water level in the reactor pressure vessel. As a result, part of the core fuel may be exposed above the water surface, resulting in insufficient cooling.

When the core fuel is exposed above the water surface, the zirconium cladding material of the core fuel reacts with high-temperature steam (water-metal reaction), oxidizing the zirconium and simultaneously reducing the water to generate hydrogen. Since the water-metal reaction is generally an exothermic reaction, the heat generation raises the temperature of the steam and the cladding tube, thereby increasing the water-metal reaction rate and the amount of hydrogen generated.

Even in such a situation, the heat of the core fuel is usually removed by water injection into the reactor pressure vessel using portable water injection equipment, etc., and the accident is settled. Then, if the event progresses further, the core fuel is damaged or melted, and the damaged/melted core falls and deposits in the lower plenum of the reactor pressure vessel. If the situation in which water cannot be injected into the core fuel accumulated in the lower plenum continues, decay heat released from the accumulated core fuel will damage the pressure boundary (lower head) that supports the lower plenum below. As a result, core fuel falls into the reactor containment vessel.

The reactor containment floor below the reactor pressure vessel is generally made of concrete. Therefore, additional hydrogen is generated by the water-metal reaction between the metals (zirconium and iron) contained in the dropped high-temperature core fuel and the moisture contained in the concrete.

In the case of a boiling water reactor, the hydrogen generated in the reactor pressure vessel or the reactor containment vessel by the above mechanism is retained in the reactor containment vessel filled with inert gas (nitrogen). Therefore, the reaction (hydrogen combustion) between hydrogen and oxygen does not occur, but hydrogen has a small molecular diameter and leaks slightly into the reactor building through the penetration of the reactor containment vessel. Since the reactor building is in an air atmosphere, there is a risk of damage to the reactor building due to a combustion reaction between high-temperature leaked hydrogen and oxygen. In order to prevent damage to the reactor building, it is effective to selectively release hydrogen generated in the reactor containment vessel outside the reactor building.

A metal film based on Pd or Nb exists as a film (hydrogen permeable film) that selectively allows only hydrogen to pass through without allowing radioactive substances and water vapor to pass through. However, it is known that metal films have a higher risk of breaking due to hydrogen embrittlement when the amount of solid solution of hydrogen increases. For example, when hydrogen is dissolved in a Pd film at a low temperature, a phase transformation occurs, resulting in a state in which two types of hydride phases coexist. It is known that the lattice constants of the two types of hydride phases are different, causing strain in the Pd film and destroying the Pd film. Therefore, when using a Pd film as a hydrogen-permeable film, it is necessary to prevent hydrogen embrittlement by preheating using a heater or the like.

In Patent Document 1, ``When all AC power is lost due to a loss of cooling water accident, hydrogen, radionuclides and water vapor are released into the reactor containment vessel from the fractured portion of the piping connected to the reactor pressure vessel. In the catalytic hydrogen treatment device 2, a catalyst layer 22 and heat transfer tubes 5 of a heat exchanger 4 are installed in a casing 3. High-temperature steam containing hydrogen and radionuclides is supplied into the heat transfer tubes 5, and the casing is It heats the later-described gas supplied to the inside 3. The water vapor is condensed inside the heat transfer tube 5 to generate mist, which is removed together with the radionuclides by the mist separator 6. The mist separator 6 supplies the inside of the casing 3 from the mist separator 6. The hydrogen-containing gas is heated by the water vapor and guided into the catalyst layer 22. Hydrogen is combined with oxygen in the catalyst layer 22 to become water vapor. (see abstract).

JP 2014-48043 A

According to the conventional technology, it is possible to selectively release hydrogen outside the reactor building while confining radioactive substances and water vapor in the reactor containment vessel by the hydrogen-permeable membrane. However, if the amount of heat transferred to the hydrogen gas is insufficient and the hydrogen permeable membrane is not sufficiently preheated, there is a risk that the hydrogen permeable membrane will break due to hydrogen embrittlement.

Patent Literature 1 describes a method for preventing embrittlement damage of a hydrogen permeable membrane by increasing the hydrogen gas temperature using a heat exchanger. However, compared to liquids such as water, gas has high heat insulation performance, and the amount of heat transfer from the heat transfer tube of the heat exchanger to hydrogen gas is limited. there remains a risk of

The present invention has been made in view of such a background, and an object of the present invention is to maintain the resistance of the reactor containment vessel against accidents while increasing the resistance to hydrogen.

In order to solve the above-described problems, the present invention provides a reactor pressure vessel containing core fuel loaded with a plurality of fuel assemblies, a dry well space around the reactor pressure vessel, and an airtight seal with the dry well space. A pressure suppression chamber that is a space partitioned by walls, a pressure suppression pool that is formed by storing water inside the pressure suppression chamber, and a vent pipe that connects the dry well space and the pressure suppression pool. And, a hydrogen treatment system provided in a reactor containment vessel containing a water vapor contained in the introduced gas by being installed outside the reactor containment vessel and immersed in the heat removal pool water a water condenser for condensing the water into water, and an ejector installed outside the reactor containment vessel, which does not require preheating, and selectively ejects hydrogen and the water vapor to the outside, and the water The upstream side of the condenser is connected to the dry well space by a dry well gas lead-in pipe, the downstream side of the water condenser is connected to the inside of the reactor containment vessel by a condensed water discharge pipe, connected upstream of said ejector by a first non-condensable gas exhaust pipe, downstream of said ejector connected to said pressure suppression pool by a second non-condensable gas exhaust pipe; The outlet end of the non-condensable gas discharge pipe is arranged at a position higher than the position of the vent pipe , and has a hydrogen storage space having a predetermined sealed space inside, wherein at least the hydrogen and a cover installed so that the portion where the water vapor is discharged is sealed from the outside, the inner space of the cover and the inside of the hydrogen storage space are connected by a hydrogen discharge pipe, and the hydrogen The outlet end of the discharge tube is connected to the hydrogen storage space via a second check valve, the second check valve allowing gas to flow from the discharger to the hydrogen storage space. It is characterized by being installed like this .
Other solutions will be described as appropriate in the embodiments.

According to the present invention, it is possible to maintain the resistance of the containment vessel against accidents while increasing the resistance to hydrogen.

1 is a system diagram of a reactor containment vessel and a hydrogen treatment system in a first embodiment; FIG. FIG. 2 is a diagram showing the appearance of the hydrogen discharger in the first embodiment; It is a system system diagram of a reactor containment vessel and a hydrogen treatment system in a second embodiment. It is a system system diagram of a reactor containment vessel and a hydrogen treatment system in a 3rd embodiment. It is a system system diagram of a reactor containment vessel and a hydrogen treatment system in a 4th embodiment. It is a system system diagram of a reactor containment vessel and a hydrogen treatment system in 5th Embodiment. FIG. 11 is a diagram showing the appearance of a hydrogen discharger in a fifth embodiment; It is a system system diagram of the reactor containment vessel and the hydrogen processing system in 6th Embodiment. It is a system system diagram of a reactor containment vessel and a hydrogen treatment system in 7th Embodiment. It is a system system diagram of a reactor containment vessel and a hydrogen treatment system in 8th Embodiment. It is a system system diagram of the reactor containment vessel and the hydrogen station system in the ninth embodiment. It is a system system diagram of the reactor containment vessel and the hydrogen treatment system in 10th Embodiment.

Next, an embodiment (referred to as "embodiment") of the hydrogen treatment system Z of the present invention will be described in detail with appropriate reference to the drawings.

[First embodiment]
(Hydrogen treatment system Z)
FIG. 1 is a system system diagram of a reactor containment vessel 1 and a hydrogen treatment system Z in the first embodiment.
The hydrogen treatment system Z is installed in the reactor containment vessel 1 and has a heat exchanger 12 and a hydrogen discharger 17 . The upstream side of the heat exchanger 12 is connected to the dry well 4 of the reactor containment vessel 1 by a dry well gas lead-in pipe 13 . Further, the downstream side of the heat exchanger 12 is connected to the water of the pressure suppression pool 5b by a condensed water discharge pipe 14. As shown in FIG. Furthermore, the upstream side of the hydrogen discharger 17 is connected to the downstream side of the heat exchanger 12 by a first non-condensable gas discharge pipe 15a. The downstream side of the hydrogen discharger 17 is connected to the water of the pressure suppression pool 5b by a second non-condensable gas discharge pipe 15b. The first non-condensable gas discharge pipe 15a and the second non-condensable gas discharge pipe 15b are collectively referred to as the non-condensable gas discharge pipe 15 as appropriate.

Here, the dry well gas lead-in pipe 13 is for guiding the steam generated when heat is removed from the core fuel 2 in the reactor pressure vessel 3 or the reactor containment vessel 1 to the heat exchanger 12 . The condensed water discharge pipe 14 is for discharging the water condensed in the heat exchanger 12 to the pressure suppression pool 5 b inside the pressure suppression chamber 5 . The non-condensable gas discharge pipe 15 discharges hydrogen discharger upstream gas, which is non-condensable gas that cannot be condensed in the heat exchanger 12, to the pressure suppression pool 5b.

The heat exchanger 12 is a vertical heat exchanger, and includes a heat exchanger upper header 12a, heat exchanger heat transfer tubes 12b, and a heat exchanger lower header 12c. The heat exchanger 12 is immersed in heat removal pool water 16 a stored in the heat removal pool 16 .

The outlet end of the non-condensable gas exhaust pipe 15 is connected to the pressure suppression pool 5b above the uppermost one of the three horizontal vent pipes 10a. In this embodiment, the hydrogen discharger 17 has hollow fiber membranes 17a. The hydrogen discharger 17 selectively discharges small-sized molecules such as hydrogen and water vapor flowing through the hollow fiber membrane 17a to the outside of the membrane using the partial pressure difference across the membrane as a driving force. At the same time, the hydrogen ejector 17 is permeable to relatively larger molecules than hydrogen and water vapor, such as nitrogen, volatile radioactive substances (Cs, I, etc.), and radioactive noble gases (Kr, Xe, etc.). It can be kept inside the non-condensable gas discharge pipe 15 without any problem. That is, the hydrogen discharger 17 releases hydrogen and water vapor to the outside of the system, and retains other nitrogen, volatile radioactive substances, and radioactive noble gases inside the system. Here, "outside the system" means at least outside the reactor containment vessel 1, preferably outside the reactor building B. That is, as shown in FIG. 1, the hydrogen ejector 17 is installed at least outside the reactor containment vessel 1, preferably outside the reactor building B. As shown in FIG. By installing the hydrogen ejector 17 outside the reactor building B, the hydrogen ejected from the hydrogen ejector 17 can be discharged to the atmosphere outside the reactor building B.

Moreover, "within the system" means the inside of the containment vessel 1 and the inside of the hydrogen treatment system Z. In addition, as a film applicable to the hollow fiber membrane 17a, a polymer film containing polyimide as a main component, a ceramic film containing silicon as one of its components, and a graphene oxide film containing carbon as a main component are listed as candidates. By using the hollow fibers 17a composed of these components, the hydrogen discharger 17 that does not require preheating and is resistant to hydrogen can be configured. The hollow fiber membrane 17a may be any membrane as long as it has the same function as these. Further, in this embodiment, the hydrogen discharger 17 is composed of the hollow fiber membranes 17a, but other types of membranes such as flat membranes are also applicable.

(Reactor containment vessel 1)
Next, the system configuration in the reactor containment vessel 1 of the modified boiling water reactor according to this embodiment will be described. In this embodiment, a reactor pressure vessel 3 containing core fuel 2 is installed in the reactor containment vessel 1 . A main steam pipe 8 is connected to the reactor pressure vessel 3 to send steam generated in the reactor pressure vessel 3 to a turbine (not shown).

A reactor containment vessel 1 is partitioned into a drywell 4 and a pressure suppression chamber 5 by a diaphragm floor 6 and a pedestal 7 made of reinforced concrete. The pressure suppression chamber 5 is composed of a gas phase portion (wet well 5a) and a cooling water pool portion (pressure suppression pool 5b). The drywell 4 and the suppression chamber 5 are interconnected by a vent pipe 10 and a vacuum breaker valve 11 .

A connecting portion between the vent pipe 10 and the dry well 4 is opened vertically. Also, the connecting portion between the vent pipe 10 and the pressure suppression pool 5b is horizontally opened as three horizontal vent pipes 10a per pipe in the vent pipe 10. As shown in FIG. The vacuum breaking valve 11 is a check valve that connects between the dry well 4 and the wet well 5a. The vacuum breaker valve 11 blocks the flow of gas from the dry well 4 toward the wet well 5a, and dries the gas in the wet well 5a when the pressure of the wet well 5a becomes higher than the pressure of the dry well 4. Drain into well 4.

A plurality of main steam safety relief valves 9 are installed in the main steam pipe 8 for the purpose of preventing overpressure and reducing pressure in the reactor pressure vessel 3 . The main steam safety relief valve 9 automatically opens when the reactor pressure vessel pressure increases above the high pressure set point. As a result, excess steam in the reactor pressure vessel 3 is discharged to the suppression pool 5b through the main steam safety relief valve exhaust pipe 9a and the main steam safety relief valve quencher 9b. Excess steam discharged is condensed by pressure suppression pool water. The term "automatically" means that the main steam safety relief valve 9 is mechanically opened and closed.

The main steam safety relief valve 9 automatically closes when the reactor pressure vessel pressure drops below the low pressure set point. As a result, the reactor pressure vessel pressure is maintained at a substantially constant level, and overpressure in the reactor pressure vessel 3 can be prevented. Some of the plurality of main steam relief safety valves 9 have an automatic pressure reducing function. The automatic depressurization function is a function that keeps the main steam safety relief valve 9 open continuously, and water is injected into the reactor pressure vessel 3 by a low-pressure core water injection system (not shown), which is one of the emergency core cooling systems (not shown). It is used when it is necessary to lower the reactor pressure vessel pressure to perform A melting valve 27 is installed below the drywell 4 to connect the drywell 4 and the pressure suppression pool 5b. Should the high-temperature molten core fuel (core fuel 2) damage the lower head 32 of the reactor pressure vessel 3 and drop into the drywell 4, the drywell 4 becomes a high-temperature environment and the melt valve 27 melts. to open automatically. As a result, the water in the suppression pool 5b is supplied to the drywell 4, and the dropped high-temperature molten core (core fuel 2) can be cooled. The term "automatically" means that the melting valve 27 is mechanically opened and closed by its structure.

(When the main steam pipe 8 breaks)
The operation of the hydrogen treatment system Z in the reactor containment vessel 1 in this embodiment when the main steam pipe 8 is broken will be described below. When the main steam pipe 8 breaks, high-temperature steam flows out from the reactor pressure vessel 3 to the dry well 4 through the broken opening. At the same time, cooling water is lost from the reactor pressure vessel 3, and the water level in the reactor pressure vessel 3 is lowered. At this time, water is normally injected into the reactor pressure vessel 3 by a high-pressure core water injection system (not shown) and an emergency core cooling system (not shown) such as a low-pressure water injection system. water level is maintained above a certain level. Therefore, the core fuel 2 will not be exposed above the water surface and fall into cooling failure.

Heat removal from the reactor containment vessel 1 can also be performed by a residual heat removal system (not shown), which is one of the emergency core cooling systems. Therefore, it is possible to prevent overpressure damage and overheat damage of the containment vessel 1 due to accumulation of energy.

However, assuming that the emergency core cooling system (not shown) does not operate (when water injection and heat removal are not performed), the decay heat generated from the core fuel 2 causes the inside of the reactor pressure vessel 3 to As the coolant (water) boils, the water level in the reactor pressure vessel 3 continues to drop, and the core fuel 2 is exposed above the water surface, resulting in cooling failure. When the core fuel 2 is exposed above the water surface, hydrogen is generated by a water-metal reaction between the cladding material (zirconium) of the core fuel and steam.

The following is a detailed description of how the accident progressed assuming that the emergency core cooling system (not shown) is inoperative. The steam generated inside the reactor pressure vessel 3 flows into the drywell 4 through the broken opening of the main steam pipe 8, and the internal pressure of the drywell 4 rises. Immediately after the breakage of the main steam pipe 8 occurs, the flow rate of steam flowing into the drywell 4 from the breakage port of the main steam pipe 8 is large. Therefore, the water vapor flowing into the dry well 4 and the non-condensable gas (nitrogen) pre-filled in the dry well 4 are driven by the pressure difference between the dry well 4 and the pressure suppression chamber 5 to drive the vent pipe 10. Push down the water level inside. As a result, the water level of the vent pipe 10 is lowered below the height of the horizontal vent pipe 10a, and the gas in the dry well 4 (dry well gas; nitrogen, hydrogen, water vapor, volatile radioactive substances, radioactive noble gases) is discharged from the horizontal vent pipe 10a into the suppression pool 5b in the pressure suppression chamber 5.

Of the dry well gas discharged from the horizontal vent pipe 10a, nitrogen is accumulated in the wet well 5a, and water vapor is condensed by water in the suppression pool 5b. Due to the water vapor condensation function of the pressure suppression pool 5b, the pressure rise in the reactor containment vessel 1 is effectively suppressed. However, as the energy of steam is accumulated in the suppression pool 5b, the water temperature of the suppression pool 5b and the internal pressure of the containment vessel 1 gradually rise. In this embodiment, since it is assumed that the emergency core cooling system (not shown) is not in operation, after a certain amount of time has passed since the breakage of the main steam pipe 8, the core fuel 2 is exposed above the water surface and hydrogen is released. Occur.

In addition, since it is assumed that the emergency core cooling system (not shown) is inoperative, the core fuel 2 will be damaged if the water level in the reactor pressure vessel 3 continues to drop. As a result, the fuel pellets (core fuel 2), volatile radioactive substances such as Cs and I, and radioactive noble gases such as Kr and Xe held in the fuel cladding are also released into the reactor pressure vessel 3. be.

On the other hand, the amount of steam generated gradually decreases due to a decrease in the amount of cooling water contacting the core fuel 2 due to a decrease in decay heat and a decrease in water level. As a whole, the total amount of water vapor, hydrogen, volatile radioactive substances, and radioactive noble gases flowing out from the reactor pressure vessel 3 to the dry well 4 through the fracture opening of the main steam pipe 8 is gradually reduced. The pressure difference between 4 and the pressure suppression chamber 5 decreases. As a result, the water level in the vent pipe 10, which has been pushed down by the generation of a large amount of steam, rises. As the water level of the vent pipe 10 rises, the horizontal vent pipe 10a is submerged, and the inflow of the dry well gas from the dry well 4 to the pressure suppression chamber 5 through the vent pipe 10 is stopped.

(Operation of the hydrogen treatment system Z when the main steam pipe 8 is broken)
After the inflow of the dry well gas into the pressure suppression chamber 5 through the vent pipe 10 is stopped, the hydrogen treatment system Z of this embodiment starts full-scale operation. The driving source of the hydrogen treatment system Z is the pressure difference between the dry well 4 and the pressure suppression chamber 5 as well as the vent pipe 10 . However, as shown in FIG. 1, the opening height of the non-condensable gas discharge pipe 15 in the pressure suppression pool 5b is set at a position higher than that of the horizontal vent pipe 10a. Therefore, in the non-condensable gas discharge pipe 15, the water level of the portion immersed in the pressure suppression pool 5b is lowered, and the dry well 4 required to discharge the gas downstream of the hydrogen discharger to the pressure suppression pool 5b. The pressure difference with the pressure suppression chamber 5 is smaller than the pressure difference pushing down the inside of the vent pipe 10 . Therefore, even if there is a pressure difference between the dry well 4 and the pressure suppression chamber 5 where the vent pipe 10 does not operate, the dry well gas (nitrogen, hydrogen, water vapor, volatile radioactive substances, radioactive rare gas) can be discharged.

The operation of the hydrogen treatment system Z of this embodiment will be described below. The dry well gas is led to the heat exchanger 12 via the dry well gas lead-in pipe 13 (solid arrow). The water vapor in the dry well gas is heat-removed by the heat removal pool water 16a and becomes condensed water when passing through the heat exchanger heat transfer tubes 12b. Thereby, the water vapor in the dry well gas can be reused for heat removal. Condensed water, hydrogen, nitrogen, a small amount of uncondensed water vapor, and volatile radioactive substances/radioactive noble gases flow into the heat exchanger lower header 12c, but the condensed water flows into the lower part of the heat exchanger lower header 12c. It accumulates and is discharged to the suppression pool 5b through the condensed water discharge pipe 14 by gravity (one-dot chain line arrow). Gas containing nitrogen, a small amount of uncondensed water vapor, volatile radioactive substances, and radioactive noble gases (hydrogen discharger upstream gas), which are substances other than condensed water condensed by the heat exchanger 12 in the dry well gas uses the pressure difference between the dry well 4 and the pressure suppression chamber 5 as a driving force to flow through the non-condensable gas discharge pipe 15 toward the suppression pool 5b (broken line arrow).

When the hydrogen ejector upstream gas flows into the hydrogen ejector 17, hydrogen and a small amount of water vapor are selectively exhausted to the outside of the hydrogen ejector 17 via the hollow fiber membranes 17a. Hydrogen, nitrogen, which has a relatively large molecular size with respect to water vapor, volatile radioactive substances, and radioactive noble gases do not permeate the hollow fiber membrane 17a, and pass through the outlet of the second non-condensable gas discharge pipe 15b. It is discharged from the end into the suppression pool 5b (broken line arrow). By doing so, it is possible to prevent the inside of the reactor building B and the inside of the reactor containment vessel 1 from being filled with volatile radioactive substances and radioactive noble gases.

The hydrogen discharger 17 used in this embodiment does not require preheating unlike a hydrogen permeable membrane such as a Pd membrane, but it releases not only hydrogen but also water vapor with a small molecular size, which is necessary for cooling the core fuel 2, to the outside of the system. have the property of Thus, the hydrogen discharger 17 permeates not only hydrogen but also water vapor and discharges it to the outside of the system. However, since steam can be used for heat removal, it is desirable not to discharge it to the outside of the system.

Therefore, in this embodiment, by installing the hydrogen discharger 17 in the non-condensable gas discharge pipe 15 on the downstream side of the heat exchanger 12, most of the water vapor after condensing in the heat exchanger 12 is It is possible to selectively pass only the hydrogen ejector upstream gas containing no water vapor through the hydrogen ejector 17 . That is, since water vapor in the dry well gas has been removed by the heat exchanger 12 , hydrogen discharger upstream gas containing almost no water vapor is introduced into the hydrogen discharger 17 . As a result, only hydrogen can be selectively discharged out of the system, and at the same time, by confining volatile radioactive substances and radioactive noble gases inside the reactor containment vessel 1, the radiation effect on the surrounding environment is minimized. can be

Further, by supplying the condensed water generated by the heat exchanger 12 to the suppression pool 5b, the heat of the reactor containment vessel 1 can be removed, so the risk of damage to the reactor containment vessel 1 due to energy accumulation can be reduced. . Furthermore, since the hydrogen discharger upstream gas is cooled by the heat exchanger 12 and has a lower temperature than the dry well gas, the risk of high temperature damage to the hollow fiber membranes 17a of the hydrogen discharger 17 can be reduced.

As described above, according to the present embodiment, even if the main steam pipe 8 is broken, hydrogen can be released without using a dynamic device such as an electric pump or a hydrogen permeable membrane that may become embrittled in a low temperature environment. It can be discharged out of the system.

(When all AC power supply is lost)
So far, the operation of the hydrogen treatment system Z when the main steam pipe 8 is broken has been described. realizable. The operation of the hydrogen treatment system Z when all AC power sources are lost will be described below.
When a total AC power source blackout occurs due to the rupture of the main steam pipe 8, the reactor pressure vessel 3 is isolated by closing an isolation valve (not shown) installed in the main steam pipe 8. . As a result, the pressure in the reactor pressure vessel 3 rises. When the pressure in the reactor pressure vessel 3 reaches or exceeds the high pressure set value of the main steam relief safety valve 9, the main steam safety relief valve 9 automatically opens. As a result, water vapor present inside the reactor pressure vessel 3 is discharged into the suppression pool 5b via the main steam safety relief valve exhaust pipe 9a and the main steam safety relief valve quencher 9b, and is condensed.

By absorbing the energy of the released water vapor, the water temperature in the pressure suppression pool 5b rises. As a result, the pressure in the pressure suppression chamber 5 becomes higher than the pressure in the dry well 4, so that the gas (nitrogen and steam at saturation pressure) in the wet well 5a flows into the dry well 4 via the vacuum breaking valve 11, The pressures of the dry well 4 and the wet well 5a are almost equalized. At this time, there is no pressure difference between the dry well 4 and the suppression chamber 5, and the hydrogen treatment system Z of the containment vessel 1 does not operate.

On the other hand, in the case of total AC power source loss, since it is assumed that all AC power sources including the emergency diesel generator are lost, the reactor core isolation cooling system that operates with the high pressure steam existing inside the reactor pressure vessel 3 as the driving force All emergency core cooling systems (not shown) will fail, except for the system (not shown). Since the amount of water injected into the reactor by the reactor core isolation cooling system is controlled by the DC power supply, water injection into the reactor pressure vessel 3 can be continued while the DC power supply is secured. The time cooling system loses its function.

When the reactor core isolation cooling system loses its function, steam inside the reactor pressure vessel 3 flows out to the suppression pool 5b through the main steam safety relief valve 9, and the water level of the reactor pressure vessel 3 gradually decreases. do. As a result, the core fuel 2 is exposed above the water surface and falls into cooling failure.

Hydrogen generated by the water-metal reaction and steam generated by the decay heat of the submerged core fuel 2 flow through the main steam safety relief valve 9 into the pressure suppression pool 5b. At this time, water vapor condenses, but hydrogen, which is a non-condensable gas, flows into the wet well 5a, and nitrogen, hydrogen, and water vapor at saturation pressure in the wet well 5a flow into the dry well 4 through the vacuum breaking valve 11. . Thereby, the pressure equalization state of the dry well 4 and the wet well 5a is maintained.

If the event progresses further without water being injected into the reactor pressure vessel 3 by portable equipment (not shown), the core fuel 2 is damaged or melted and falls from the core 33 to the lower plenum 31 of the reactor pressure vessel 3. and deposit. If the state in which water cannot be injected into the core fuel 2 deposited in the lower plenum 31 continues, decay heat released from the deposited core fuel 2 damages the lower head 32 , and the core fuel 2 falls into the drywell 4 .

At this time, the temperature of the atmosphere in the dry well 4 rises due to the high-temperature molten core fuel (core fuel 2), the melt valve 27 automatically opens, and the water in the pressure suppression pool 5b accumulates in the dry well 4. Water is injected onto the core fuel 2). As a result, the molten core fuel is cooled and a large amount of water vapor is generated in the drywell 4 , so that the pressure in the drywell 4 becomes higher than the pressure in the suppression chamber 5 .

After that, the hydrogen treatment system Z driven by the pressure difference between the dry well 4 and the pressure suppression chamber 5 starts to operate in the same manner as when the main steam pipe 8 is broken as described above. As a result, the heat in the containment vessel 1 can be removed by supplying the condensed water produced by condensing the steam in the heat exchanger 12 to the suppression pool 5b. In addition to this, overpressure in the containment vessel 1 can be prevented by discharging hydrogen from the hydrogen discharger 17 to the outside of the system.

As described above, the hydrogen treatment system Z maintains heat removal from the reactor containment vessel 1 after the molten core fuel falls into the drywell 4 when a total AC power source blackout occurs, and Overpressure in the container 1 can be prevented.

Specifically, while confining volatile radioactive substances and radioactive noble gases inside the reactor containment vessel 1, only hydrogen, which causes overpressure of the reactor containment vessel 1, can be released outside the system. Since it is low cost and can minimize the radiation effect on the surroundings, it is expected that it may be applied to the entire boiling water reactor if it is put into practical use. That is, instead of a metal membrane (hydrogen permeable membrane) that may cause hydrogen embrittlement at low temperatures, a hollow fiber membrane 17a with high low temperature resistance is used, in other words, a hollow fiber that can be used without preheating. Only hydrogen can be discharged out of the system using the membrane 17a. As a result, it is possible to significantly reduce the risk of damage to the containment vessel 1 .

FIG. 2 is a diagram showing the appearance of the hydrogen discharger 17 in the first embodiment.
As shown in FIG. 2, the hydrogen discharger 17 is preferably installed in each of the first non-condensable gas discharge pipe 15a and the first non-condensable gas discharge pipe 15a by flange connection using a flange 17b. By adopting such an installation method, the hydrogen discharger 17 (hollow fiber membrane 17a) can be easily replaced according to the state of deterioration.

[Second embodiment]
A hydrogen treatment system Za according to a second embodiment of the present invention will be described below with reference to FIG. In FIG. 3, the same reference numerals as those shown in FIG. 1 denote the same parts, so the detailed explanation thereof will be omitted, and the explanation will focus on the differences.

FIG. 3 is a system diagram of the containment vessel 1 and the hydrogen treatment system Za in the second embodiment.
The difference between the hydrogen treatment system Z in FIG. 1 and the hydrogen treatment system Za in FIG. Another feature is that the reactor pressure vessel decompression valve 19 is provided in the reactor pressure vessel decompression pipe 19a. By opening the reactor pressure vessel decompression valve 19, the internal pressure of the reactor pressure vessel 3 can be released to the drywell 4 via the reactor pressure vessel decompression pipe 19a. For the reactor pressure vessel decompression valve 19, it is conceivable to apply a blast valve with high operational reliability, a fusion valve that automatically opens in a high temperature environment at the time of an accident, or the like.

The operation of the hydrogen treatment system Za for the containment vessel 1 according to the present embodiment will be described below.
As shown in the first embodiment, the hydrogen treatment system Za of the containment vessel 1 operates using the pressure difference between the dry well 4 and the pressure suppression chamber 5 as a driving force. The start time is later than when the main steam pipe 8 is broken, and is after the molten core fuel (core fuel 2) has fallen into the dry well 4.

On the other hand, in the configuration of the second embodiment, it is possible to operate the hydrogen treatment system Za of the reactor containment vessel 1 promptly even in the event of a total AC power source failure by the operation described below. Specifically, in the unlikely event that water cannot be injected into the reactor pressure vessel 3 due to failure to start the reactor core isolation cooling system due to some kind of malfunction or loss of function of the reactor core core isolation cooling system due to DC power supply depletion. By opening the reactor pressure vessel decompression valve 19 , the water vapor in the reactor pressure vessel 3 is released to the dry well 4 in the same manner as when the main steam pipe 8 is broken. As a result, the pressure difference between the dry well 4 and the pressure suppression chamber 5 can be ensured. As a result, the hydrogen treatment system Za of the containment vessel 1 can be operated, as described for the breakage of the main steam pipe 8 in the first embodiment.

As described above, according to the second embodiment, the hydrogen treatment system Za can be quickly started even in an accident event such as a loss of all AC power sources, where the pressure difference between the dry well 4 and the pressure suppression chamber 5 does not quickly occur. It becomes possible to

[Third embodiment]
A third embodiment of the hydrogen treatment system Zb for the containment vessel 1 will be described below with reference to FIG. In FIG. 4, parts having the same reference numerals as those shown in FIG. 1 are the same parts, so detailed description thereof will be omitted, and the description will focus on the differences.

FIG. 4 is a system diagram of the containment vessel 1 and the hydrogen treatment system Zb in the third embodiment.
The difference between FIG. 1 and FIG. 4 is that the hydrogen ejector 17 is installed inside the vertical duct 18 . In the first embodiment (see FIG. 1), when the hydrogen discharged from the hydrogen discharger 17 stays around the hydrogen discharger 17, the hydrogen partial pressure difference across the hollow fiber membrane 17a becomes small, and the hydrogen discharger The hydrogen removal performance of 17 may decrease. On the other hand, according to the third embodiment, the inside of the vertical duct 18 becomes relatively light hydrogen discharged from the hydrogen ejector 17, and the outside of the vertical duct 18 becomes relatively heavy air. As a result, a natural circulation flow driven by the density difference between the inside and outside of the vertical duct 18 is generated. Specifically, light hydrogen is discharged from above the vertical duct 18 (arrow 101). Along with this, air enters the vertical duct 18 from below (arrow 102). Thereby, the hydrogen discharged from the hydrogen discharger 17 can be effectively removed from the vicinity of the hollow fiber membrane 17a. In addition, since the hydrogen discharged from the hydrogen discharger 17 can be discharged from a high place, it is possible to reduce the risk of injury to emergency workers and damage to nuclear power plant equipment due to hydrogen combustion occurring near the ground.

As described above, according to the third embodiment, in addition to the effects shown in the first embodiment, deterioration of the performance of the hydrogen discharger 17 due to retention of hydrogen discharged from the hydrogen discharger 17 in the vicinity of the hollow fiber membranes 17a can be prevented. can be prevented. Furthermore, since hydrogen is discharged from a high place, it is possible to reduce the risk of injury to emergency workers and damage to nuclear power plant equipment due to hydrogen combustion near the ground.

In addition, although the vertical duct 18 is used in the hydrogen treatment system Zb shown in the third embodiment, the same application effect can be obtained even if the exhaust stack 24 described later in FIG. 6 is used instead of the vertical duct 18. Obtainable.

[Fourth embodiment]
A fourth embodiment of the hydrogen treatment system Zc will be described below with reference to FIG. In FIG. 5, parts having the same reference numerals as those shown in FIG. 1 are the same parts, so detailed explanation thereof will be omitted, and the explanation will focus on the points of difference.

FIG. 5 is a system diagram of the containment vessel 1 and the hydrogen treatment system Zc in the fourth embodiment.
Differences between FIG. 1 and FIG. 5 are as follows.
(A1) The first non-condensable gas discharge pipe 15a is provided with an upstream isolation valve 20a. A downstream isolation valve 20b is provided in the second non-condensable gas discharge pipe 15b. The upstream isolation valve 20a and the downstream isolation valve 20b are collectively referred to as the isolation valve 20 as appropriate.
(A2) The further upstream side of the upstream isolation valve 20a and the further downstream side of the downstream isolation valve 20b are connected by the non-condensable gas bypass pipe 21, and the non-condensable gas bypass pipe 21 is connected to the non-condensable gas bypass valve. 22 are installed.

A case where the hydrogen discharger 17 (hollow fiber membrane 17a) is damaged in the configuration of the first embodiment shown in FIG. 1 will be described. In the configuration of FIG. 1, it is conceivable to provide emergency isolation valves (not shown) in each of the dry well gas lead-in pipe 13, the condensed water discharge pipe 14, and the non-condensable gas discharge pipe 15. FIG. This emergency isolation valve is different from the isolation valve 20 and the non-condensable gas bypass valve 22 described above.

In the configuration of FIG. 1, if the hydrogen discharger 17 (hollow fiber membrane 17a) is damaged, the dry well gas containing volatile radioactive substances and radioactive noble gases from the damaged part of the hollow fiber membrane 17a will flow out of the system. To prevent spillage, it is conceivable to close these emergency isolation valves, not shown. However, closing these three emergency isolation valves disables the heat exchanger 12 in addition to the hydrogen ejector 17 .

In contrast, in the fourth embodiment, when the hydrogen discharger 17 is damaged, the upstream isolation valve 20a and the downstream isolation valve 20b are closed, and the non-condensable gas bypass valve 22 is opened. As a result, although the flow of the hydrogen discharger upstream gas introduced into the hydrogen discharger 17 is stopped, the gas flow through the non-condensable gas bypass pipe 21 is maintained. That is, the use of the heat exchanger 12 can be maintained. Thus, in the fourth embodiment, when the hydrogen ejector 17 is damaged, the function of removing hydrogen from the hydrogen ejector 17 is lost, but the heat removal function of the reactor containment vessel 1 by the heat exchanger 12 is maintained. be able to. The opening and closing of the isolation valve 20 and the non-condensable gas bypass valve 22 may be performed manually, or may be controlled by a control device (not shown).

As described above, according to the fourth embodiment, in addition to the effects shown in the first embodiment, even if the hydrogen discharger 17 is damaged, the amount of radioactive substances released into the surrounding environment is minimized, and heat exchange is achieved. Heat removal by the vessel 12 can continue. As a result, the risk of overpressure and overheat damage to the containment vessel 1 can be reduced.

[Fifth embodiment]
A fifth embodiment of the hydrogen treatment system Zd will be described below with reference to FIGS. 6 and 7. FIG. In FIG. 6, parts having the same reference numerals as those shown in FIG. 1 are the same parts, so detailed explanation thereof will be omitted, and the explanation will focus on the points of difference.

FIG. 6 is a system diagram of the reactor containment vessel 1 and the hydrogen treatment system Zd in the fifth embodiment.
Differences between FIG. 1 and FIG. 6 are as follows. FIG. 7 is also referred to as appropriate.
(B1) As shown in FIGS. 6 and 7, the hydrogen/steam permeable side of the hydrogen discharger 17T is covered with a unit cover 17c.
(B2) A hydrogen discharge pipe 23 extends from the unit cover 17c (see FIGS. 6 and 7). Then, as shown in FIG. 6, this hydrogen discharge pipe 23 is connected to an exhaust pipe 24 .
(B3) A hydrogen discharge pipe check valve 25 is installed at the end of the hydrogen discharge pipe 23 on the side of the exhaust pipe 24 to prevent the inflow of air from the exhaust pipe 24 side to the hydrogen discharger 17T and the reverse flow of hydrogen. ing.
The upstream side of the hydrogen discharge pipe check valve 25 (the side of the hydrogen discharger 17T) is previously filled with nitrogen at atmospheric pressure.

In the first embodiment, there is a possibility that the hydrogen discharger 17T may lose its function due to being submerged by a tsunami. Although it is possible to take measures without the unit cover 17c, such as preventing submersion by arranging the hydrogen discharger 17 at a high place, in the fifth embodiment, the hydrogen discharger 17T is covered with the unit cover 17c. and a hydrogen discharge pipe check valve 25 is provided. By doing so, it is possible to prevent the hydrogen ejector 17T from being affected by an external event such as a tsunami. Moreover, with such a configuration, the hydrogen ejector 17 does not have to be placed at a high place, and the degree of freedom in the placement position of the hydrogen ejector 17T can be increased.

In addition, by providing the hydrogen discharge pipe check valve 25 in the hydrogen discharge pipe 23, external environmental influences (moisture, soot, etc.) that may impede the function of the hydrogen discharger 17T are prevented from flowing into the hydrogen discharge pipe 23. can be prevented. This eliminates the influence of external environmental influences (moisture, soot, etc.) that may impede the functioning of the hydrogen ejector 17T.

In addition, by filling nitrogen between the hydrogen discharge pipe check valve 25 and the hydrogen discharger 17T, the influence of external environmental influences (moisture, soot, etc.) that may impede the function of the hydrogen discharger 17T is eliminated. The exclusion effect can be enhanced. Furthermore, in the fifth embodiment, the hydrogen released from the hollow fiber membrane 17a to the outside of the system is discharged into the exhaust stack 24. As shown in FIG. At this time, hydrogen is relatively light inside the exhaust stack 24, and air is relatively heavy outside. Can be ejected from high places. Specifically, light hydrogen is discharged from above the vertical duct 18 (arrow 201). Along with this, air enters the vertical duct 18 from below (arrow 202).

As described above, according to the fifth embodiment, in addition to the effects shown in the first embodiment, by discharging hydrogen from a high place, it is possible to prevent injury to emergency workers and damage to nuclear power plant equipment due to hydrogen combustion near the ground. Risk can be reduced. Furthermore, the hydrogen discharge pipe check valve 25 is provided to protect the hydrogen discharge pipe 23 from external environmental influences that may impair the function of the hydrogen discharge pipe 17T.

FIG. 7 is a diagram showing the appearance of the hydrogen discharger 17T in the fifth embodiment.
As shown in FIG. 7, the hydrogen discharger 17T shown in the fifth embodiment and the hydrogen discharge pipe 23 are desirably connected (flanged connection) with a flange 17b. By connecting in this way, the hollow fiber membrane 17a can be easily replaced according to the state of deterioration.

[Sixth embodiment]
A sixth embodiment of the hydrogen treatment system Ze will be described below with reference to FIG. In FIG. 8, parts having the same reference numerals as those shown in FIG. 6 are the same parts, so detailed explanation thereof will be omitted, and the explanation will focus on the points of difference.

FIG. 8 is a system diagram of the containment vessel 1 and the hydrogen treatment system Ze in the sixth embodiment.
The difference between FIG. 6 and FIG. 8 is that the hydrogen discharge pipe 23 is provided with a permeating gas isolation valve 20c.
The effect of the sixth embodiment will be described below based on the fifth embodiment (see FIG. 6). In the fifth embodiment, as in the first embodiment, the dry well gas lead-in pipe 13, the condensed water discharge pipe 14, and the non-condensable gas discharge pipe 15 are provided in case the hydrogen discharger 17T is damaged. It is conceivable to provide each with an emergency isolation valve (not shown). In the unlikely event that the hydrogen discharger 17T is damaged, these emergency isolation valves (not shown) are closed to prevent the dry well gas containing volatile radioactive substances and radioactive noble gases from flowing out of the system. can be prevented. However, closing these three emergency isolation valves (not shown) disables the heat exchanger 12 in addition to the hydrogen ejector 17T.

In contrast, in the sixth embodiment, in the unlikely event that the hydrogen discharger 17T is damaged, the permeating gas isolation valve 20c is closed to prevent the release of volatile radioactive substances and radioactive noble gases into the surrounding environment. can. Thus, according to the sixth embodiment, in the unlikely event that the hydrogen ejector 17T is damaged, while confining the volatile radioactive materials/radioactive noble gases in the reactor containment vessel 1, 1 can be maintained. The opening and closing of the permeating gas isolation valve 20c may be performed manually, or may be controlled by a control device (not shown).

As described above, according to the sixth embodiment, in addition to the effects shown in the fifth embodiment, even if the hydrogen discharger 17T should be damaged, the amount of radioactive substances released into the surrounding environment is minimized, and heat is generated. Heat removal by the exchanger 12 can continue. As a result, even if the hydrogen discharger 17T should be damaged, the risk of overpressure/overheat damage to the reactor containment vessel 1 can be reduced.

[Seventh embodiment]
A seventh embodiment of the hydrogen treatment system Zf will be described below with reference to FIG. In FIG. 9, the same reference numerals as those shown in FIG. 6 denote the same parts, so the detailed description thereof will be omitted, and the description will focus on the differences.

FIG. 9 is a system diagram of the containment vessel 1 and the hydrogen treatment system Zf in the seventh embodiment.
The difference between FIG. 6 and FIG. 9 is that instead of disposing the hydrogen discharge pipe check valve 25 at the end of the hydrogen discharge pipe 23 on the exhaust pipe 24 side as shown in FIG. The point is that the ends are opened into the water of the scrubbing pool 28 . In the seventh embodiment, the scrubbing pool 28 is closed, and the outlet end of the gas discharge pipe 29 extending from the scrubbing pool 28 opens into the exhaust stack 24 . Further, the gas discharge pipe 29 is previously filled with nitrogen at atmospheric pressure.

The effect of the sixth embodiment will be described below based on the fifth embodiment (FIG. 6). In the fifth embodiment, a hydrogen discharge pipe check valve 25 is provided in the hydrogen discharge pipe 23, and nitrogen is filled between the hydrogen discharge pipe check valve 25 and the hydrogen discharger 17T. As a result, in the fifth embodiment, it is possible to prevent external environmental influences (moisture, smoke, etc.) from flowing into the hydrogen discharger 17T, which may impede the function of the hydrogen discharger 17T. Therefore, external environmental influences (moisture, smoke, etc.) that may impede the function of the hydrogen ejector 17T can be eliminated. In the seventh embodiment as well, the outlet end of the gas discharge pipe 29 is sealed with water stored in the scrubbing pool 28, and the gas discharge pipe 29 is filled with nitrogen, thereby achieving the same effect as in the fifth embodiment. Obtainable. In addition, even if the hydrogen discharger 17T is damaged and volatile radioactive substances/radioactive rare gases flow out to the hydrogen discharge pipe 23, aerosols contained in the hydrogen discharger upstream gas and water-soluble substances such as CsI Most of the radioactive material can be entrapped in the scrubbing pool 28 water. As a result, long-term effects on the surrounding environment such as soil contamination due to radioactive noble gases can be suppressed.

As described above, according to the seventh embodiment, in addition to the effects shown in the fifth embodiment, even if the hydrogen discharger 17T should be damaged, the amount of radioactive substances released into the surrounding environment can be minimized. . Furthermore, in the unlikely event that the hydrogen discharger 17T is damaged, hydrogen removal by the hydrogen discharger 17T and heat removal by the heat exchanger 12 can be continued. As a result, the risk of overpressure/overheat damage to the containment vessel 1 can be significantly reduced.

In addition, in the seventh embodiment, the scrubbing pool 28 is a closed type in which the parts other than the introduction portion of the hydrogen discharge pipe 23 and the gas discharge pipe 29 are sealed. However, without being limited to this, an open type in which the upper portion of the scrubbing pool 28 is open is also possible.

[Eighth embodiment]
An eighth embodiment of the hydrogen treatment system Zg will be described below with reference to FIG. In FIG. 10, parts having the same reference numerals as those shown in FIG. 6 are the same parts, and detailed description thereof will be omitted, and the description will focus on the differences.

FIG. 10 is a system diagram of the containment vessel 1 and the hydrogen treatment system Zg in the eighth embodiment.
The difference between FIG. 6 and FIG. 10 is that the outlet end of the hydrogen discharge pipe 23 opens into the hydrogen storage space 26 having airtightness. The hydrogen storage space 26 is previously filled with an inert gas (nitrogen). Also, the outlet end of the hydrogen discharge pipe 23 and the inlet end of the hydrogen storage space 26 are connected via the hydrogen discharge pipe check valve 25 .

The effect of the eighth embodiment will be described below based on the fifth embodiment (FIG. 6). As described in the sixth embodiment, in the configuration of the fifth embodiment, the dry well gas lead-in pipe 13, the condensed water discharge pipe 14, and the non-condensable gas are provided in case the hydrogen discharger 17T is damaged. It is conceivable to provide each of the discharge pipes 15 with an emergency isolation valve (not shown). In the unlikely event that the hydrogen discharger 17T is damaged, these emergency isolation valves (not shown) are closed to prevent the outflow of the dry well gas containing volatile radioactive substances and radioactive noble gases to the outside of the system. can do. However, as described above, when the emergency isolation valve (not shown) is closed, the hydrogen discharger 17T and the heat exchanger 12 cannot be used, and both heat and hydrogen cannot be released to the outside of the system.

In contrast, in the eighth embodiment, even if the hydrogen discharger 17 is damaged, the hydrogen discharger upstream gas containing volatile radioactive substances and radioactive noble gases is accumulated in the airtight hydrogen storage space 26. . As a result, it is possible to minimize the radiation effect on the surrounding environment. In addition, by previously filling the airtight hydrogen storage space 26 with an inert gas such as nitrogen, it is possible to prevent damage to buildings and equipment due to hydrogen combustion.

As described above, according to the eighth embodiment, in addition to the effects of the fifth embodiment, even if the hydrogen discharger 17T is damaged, the hydrogen discharger upstream gas containing volatile radioactive substances and radioactive noble gases can be confined in the hydrogen storage space 26 . As a result, it is possible to reliably prevent hydrogen combustion while minimizing radiation effects on the surrounding environment.

Instead of filling the hydrogen storage space 26 with nitrogen gas, an electric hydrogen combustion device (igniter 301) (not shown) or a static catalytic hydrogen recombination device 302 (not shown) is installed in the hydrogen storage space 26. good too. In this case, the inside of the hydrogen storage space 26 may be an air atmosphere. In this case, the hydrogen discharged into the hydrogen storage space 26 via the hydrogen discharger 17T is either combusted by the igniter 301 or by the static catalytic hydrogen recombination device 302 by selectively combining oxygen and hydrogen. recombined back into water or removed by either method. As a result, damage to buildings and facilities due to hydrogen combustion can be prevented.

[Ninth Embodiment]
FIG. 11 is a system diagram of the containment vessel 1 and the hydrogen station system Zh in the ninth embodiment.
In FIG. 11, parts having the same reference numerals as those shown in FIG. 1 are the same parts, so detailed explanation thereof will be omitted, and the explanation will focus on the differences.
The difference between FIG. 1 and FIG. 11 is that an iodine remover 30 such as activated carbon or silver zeolite is installed before the opening of the dry well gas lead-in pipe 13 on the dry well 4 side. By doing so, the highly corrosive iodine gas (I ₂ ) is removed before flowing into the hydrogen station system Zh. By doing so, it is possible to reduce the risk of hydrogen permeation performance deterioration due to deposition of iodine on the hollow fiber membranes 17a and the risk of membrane breakage due to corrosion.

[Tenth embodiment]
FIG. 12 is a system system diagram of the containment vessel 1 and the hydrogen treatment system Zi in the tenth embodiment.
In FIG. 12, parts having the same reference numerals as those shown in FIG. 1 are the same parts, so detailed explanation thereof will be omitted and the explanation will focus on the points of difference.
Differences between FIG. 1 and FIG. 12 are as follows. In the hydrogen treatment system Z of the first embodiment (FIG. 1), the outlet end of the condensed water discharge pipe 14 is arranged in the pressure suppression pool 5b. On the other hand, in the tenth embodiment, the outlet end of the condensed water discharge pipe 14a is arranged in the space of the drywell 4 arranged below the reactor pressure vessel 3 . With this arrangement, the condensed water condensed in the heat exchanger 12 when the main steam pipe 8 is broken can be returned to the floor of the drywell 4 below the reactor pressure vessel 3 . Also, a water pool (drywell pool (not shown)) can be formed in the drywell 4 below the reactor pressure vessel 3 before the lower head 32 of the reactor pressure vessel 3 is damaged. By forming the dry well pool in advance in this way, the heat removal of the molten core fuel (core fuel 2) can be started earlier than the melting valve 27 does. As a result, it is possible to effectively suppress the generation of hydrogen caused by the water-metal reaction between the metals (zirconium and iron) contained in the molten core fuel and the moisture contained in the concrete.

In each embodiment, the hydrogen treatment systems Z, Za to Zi have been described using the vertical heat exchanger 12, but the heat exchanger lower header 12c or It is also possible to use a horizontal heat exchanger 12 in which a steam-water separation space having an equivalent function is installed downstream of the heat exchanger heat transfer tube 12b.

The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

1 Reactor Containment Vessel 3 Reactor Pressure Vessel 4 Drywell (drywell space)
5 pressure suppression chamber 5b pressure suppression pool 10 vent pipe 11 vacuum breaker valve 12 heat exchanger (water condenser)
13 Dry well gas lead-in pipe 14 Condensed water discharge pipe 15a First non-condensable gas discharge pipe 15b Second non-condensable gas discharge pipe 17 Hydrogen discharger (discharger)
17b Flange (provides flange connection)
17c Unit cover (cover)
18 vertical duct (duct)
19 Reactor pressure vessel decompression valve (decompression valve)
19a Reactor pressure vessel decompression pipe 20a Upstream isolation valve (first stop valve)
20b downstream isolation valve (first stop valve)
20c Permeate gas isolation valve (second stop valve)
21 non-condensable gas bypass pipe (bypass pipe)
22 non-condensable gas bypass valve (first stop valve)
23 Hydrogen discharge pipe 24 Exhaust pipe 25 Hydrogen discharge pipe check valve (first check valve, second check valve)
26 hydrogen storage space 27 melting valve 28 scrubbing pool 29 gas release pipe 30 iodine removal device 301 igniter (electric hydrogen combustion device)
302 Static catalytic hydrogen recombination device Z, Za ~ Zi Hydrogen treatment system

Claims (14)

a reactor pressure vessel containing core fuel loaded with a plurality of fuel assemblies;
a drywell space around the reactor pressure vessel;
a pressure suppression chamber that is a space separated from the drywell space by an airtight wall; a pressure suppression pool that is formed by storing water inside the pressure suppression chamber;
a vent pipe connecting the drywell space and the pressure suppression pool;
A hydrogen treatment system provided in a reactor containment vessel containing
a water condenser that is installed outside the reactor containment vessel and is immersed in the heat removal pool water to condense water vapor contained in the introduced gas into water;
an ejector that is installed outside the reactor containment vessel, does not require preheating, and selectively ejects hydrogen and the steam to the outside;
has
The upstream side of the water condenser is connected to the drywell space by a drywell gas lead-in pipe,
The downstream side of the water condenser is connected to the inside of the reactor containment vessel by a condensed water discharge pipe, and is connected to the upstream side of the discharger by a first non-condensable gas discharge pipe,
the downstream side of said ejector is connected to said pressure suppression pool by a second non-condensable gas exhaust pipe;
The outlet end of the second non-condensable gas discharge pipe is arranged at a position higher than the position of the vent pipe ,
Equipped with a hydrogen storage space having a predetermined space sealed inside,
In the discharger, at least a portion where the hydrogen and the water vapor are discharged is provided with a cover installed so as to be sealed from the outside,
the interior space of the cover and the interior of the hydrogen storage space are connected by a hydrogen discharge pipe,
an outlet end of the hydrogen discharge pipe is connected to the hydrogen storage space through a second check valve;
The second check valve is positioned to allow gas to flow from the ejector to the hydrogen storage space.
A hydrogen treatment system characterized by: a reactor pressure vessel containing core fuel loaded with a plurality of fuel assemblies;
a drywell space around the reactor pressure vessel;
a pressure suppression chamber that is a space separated from the drywell space by an airtight wall; a pressure suppression pool that is formed by storing water inside the pressure suppression chamber;
a vent pipe connecting the drywell space and the pressure suppression pool;
A hydrogen treatment system provided in a reactor containment vessel containing
a water condenser that is installed outside the reactor containment vessel and is immersed in the heat removal pool water to condense water vapor contained in the introduced gas into water;
an ejector that is installed outside the reactor containment vessel, does not require preheating, and selectively ejects hydrogen and the steam to the outside;
has
The upstream side of the water condenser is connected to the drywell space by a drywell gas lead-in pipe,
The downstream side of the water condenser is connected to the inside of the reactor containment vessel by a condensed water discharge pipe, and is connected to the upstream side of the discharger by a first non-condensable gas discharge pipe,
the downstream side of said ejector is connected to said pressure suppression pool by a second non-condensable gas exhaust pipe;
The outlet end of the second non-condensable gas discharge pipe is arranged at a position higher than the position of the vent pipe ,
Equipped with a hydrogen storage space having a predetermined space sealed inside,
In the discharger, at least a portion where the hydrogen and the water vapor are discharged is provided with a cover installed so as to be sealed from the outside,
the interior space of the cover and the interior of the hydrogen storage space are connected by a hydrogen discharge pipe,
an outlet end of the hydrogen discharge pipe is connected to the hydrogen storage space through a second check valve;
the second check valve is installed to allow gas to flow from the ejector to the hydrogen storage space;
The hydrogen storage space is
An electric hydrogen combustion device or a static catalytic hydrogen recombination device is installed inside
A hydrogen treatment system characterized by: 3. The hydrogen treatment system according to claim 1 or 2 , wherein the outlet end of the condensate drain pipe opens into the pressure suppression pool. 3. The hydrogen treatment system according to claim 1 or 2 , wherein an outlet end of the condensed water discharge pipe opens into the drywell space. 1 or claim 2, wherein the ejector is connected to each of the first non-condensable gas exhaust pipe and the second non-condensable gas exhaust pipe by means of a flange connection. 3. The hydrogen treatment system according to 2 . 3. The hydrogen treatment system according to claim 1 or 2, wherein an iodine removal device is provided at an entrance end of the dry well gas inlet pipe. a reactor pressure vessel decompression pipe that connects the inside of the reactor pressure vessel and the dry well space;
3. The hydrogen treatment system according to claim 1 , further comprising a decompression valve provided in the reactor pressure vessel decompression piping. Equipped with a cylindrical duct whose upper and lower parts are open to the atmosphere,
3. The hydrogen treatment system according to claim 1 or 2 , wherein the ejector is installed inside the duct. A bypass pipe connecting the first non-condensable gas discharge pipe and the second non-condensable gas discharge pipe,
In the first non-condensable gas discharge pipe, in the discharger side of the connecting portion between the first non-condensable gas discharge pipe and the bypass pipe, in the second non-condensable gas discharge pipe, 1. A first stop valve is provided on each side of the discharger and on the bypass pipe from the connecting portion between the second non-condensable gas discharge pipe and the bypass pipe. 3. The hydroprocessing system of claim 1 or claim 2 . 3. The hydrogen treatment system according to claim 1, wherein the inner space of the cover and the inner space of the exhaust stack are connected by a hydrogen discharge pipe . 11. Hydrogen according to claim 10 , wherein a first check valve for preventing the gas from flowing from the exhaust stack to the ejector is installed at the outlet end of the hydrogen exhaust pipe. processing system. 11. The hydrogen treatment system according to claim 10 , wherein the hydrogen discharge pipe is provided with a second stop valve. a scrubbing pool in which water is stored;
an exhaust stack;
with
The inner space of the cover and the water of the scrubbing pool are connected by a hydrogen discharge pipe,
3. The hydrogen treatment system according to claim 1, wherein a gas discharge pipe extending from said scrubbing pool is connected to an internal space of said exhaust stack. The discharger is configured to discharge the hydrogen and the water vapor to the outside by a hollow fiber membrane,
3. The hydrogen treatment system according to claim 1, wherein the hollow fiber membrane is composed of a polymer membrane, a ceramic membrane, or a graphene oxide membrane.

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