JP2019207174A - Nuclear power plant - Google Patents

Abstract

To provide a nuclear power plant that is capable of restricting increase in pressure inside a nuclear reactor containment vessel caused by hydrogen.SOLUTION: A nuclear power plant 1 is equipped with: a nuclear reactor containment vessel 2; and a cooling mechanism 10 which includes a cooling pool 15 filled with cooling water 15a, and cools the nuclear reactor containment vessel. In addition, the nuclear power plant 1 is provided with: a gas emission pipeline 18 which allows communication between gaseous phase sections 2a, 8a of the nuclear reactor containment vessel 2 and the cooling pool 15 of the cooling mechanism 10; and a filter 19 which is disposed in the gas emission pipeline 18, and permeates moisture vapor and hydrogen, but does not permit radioactive substances to be permeated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nuclear power plant including a cooling mechanism composed of a static cooling system.

  A nuclear power plant is equipped with a variety of safety systems in order to converge an accident even if an accident occurs. In a boiling water light water reactor (BWR), it is necessary to remove the heat generated in the core built in the reactor pressure vessel even after the reactor is shut down. For example, in the case of a loss of coolant accident (LOCA) in which the steam piping connected to the reactor pressure vessel breaks in the reactor containment vessel that contains the reactor pressure vessel, the reactor is stored in the reactor from the steam piping breakage port. Vapor flowing into the dry well of the container is led to a suppression chamber to be cooled and condensed. As a result, the water vapor discharged from the fracture opening is confined in the inside of the reactor containment vessel, and an increase in the pressure in the reactor containment vessel due to the release of the water vapor is suppressed.

  However, the temperature of the water in the suppression chamber rises by condensing water vapor in the suppression chamber. As the temperature of the water in the suppression chamber rises, the saturated water vapor pressure also rises, and the pressure in the reactor containment vessel also rises. Therefore, in a general nuclear power plant, as part of the function of the residual heat removal system (RHR), water in the suppression chamber is pumped to the heat exchanger and radiated to the outside of the reactor containment vessel through the heat exchanger. After that, it is done again to return to the suppression chamber.

  In recent years, assuming that there is an accident that all AC power in a nuclear power plant is lost, there is no need for operator operation, and static safety systems that remove heat without the need for dynamic equipment such as pumps or power supplies Is required.

  As a static safety system facility, there is one as described in Patent Document 1, for example. Patent Document 1 discloses a reactor reactor containment vessel, a reactor reactor pressure vessel installed inside the reactor reactor containment vessel, and a reactor reactor containment vessel installed below the reactor reactor containment vessel. A nuclear power plant is described that includes a suppression pool that suppresses the pressure rise in the vessel. Further, the nuclear power plant described in Patent Document 1 includes a biological shielding wall, an outer peripheral pool for storing cooling water in a space between the reactor nuclear reactor containment vessel and the biological shielding wall, and an atomic reactor from a reactor reactor pressure vessel. And a steam supply pipe drawn to the outside of the reactor reactor containment vessel. And the nuclear power plant described in patent document 1 is connected to the downstream side of the steam supply pipe, the steam condensation heat exchanger installed in the outer peripheral pool, and one end side is connected to the downstream side of the steam condensation heat exchanger. The other end side includes a condensed water discharge pipe connected to the suppression pool.

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  Moreover, when the steam pipe is broken, not only water vapor but also hydrogen may be released into the reactor containment vessel. However, since hydrogen cannot be condensed, the technique described in Patent Document 1 has a problem that the pressure inside the reactor containment vessel increases due to leaked hydrogen.

  In view of the above problems, the present object is to provide a nuclear power plant that can suppress an increase in pressure inside the reactor containment vessel due to hydrogen.

  In order to solve the above-described problems and achieve the object, a nuclear power plant has a reactor containment vessel for storing a reactor pressure vessel and a cooling pool filled with cooling water, and cools the reactor containment vessel. And a mechanism. In addition, the nuclear power plant has a gas discharge pipe that communicates the gas phase part of the reactor containment vessel and the cooling pool of the cooling mechanism, and a filter that is provided in the gas discharge pipe and transmits water vapor and hydrogen but does not transmit radioactive substances. And.

  According to the nuclear power plant configured as described above, it is possible to suppress an increase in pressure inside the reactor containment vessel due to hydrogen.

It is a schematic block diagram which shows the nuclear power plant concerning the example of 1st Embodiment. It is a perspective view which shows the gas inflow part of the gas discharge piping of the nuclear power plant concerning the example of 1st Embodiment. It is a schematic block diagram which shows the nuclear power plant concerning the example of 2nd Embodiment. It is a schematic block diagram which shows the nuclear power plant concerning the example of 3rd Embodiment. It is a schematic block diagram which shows the nuclear power plant concerning the example of 4th Embodiment.

  Hereinafter, a nuclear power plant according to an embodiment will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the common member in each figure.

1. First embodiment example 1-1. Configuration Example of Nuclear Power Plant First, the configuration of a nuclear power plant according to a first embodiment (hereinafter referred to as “this example”) will be described with reference to FIGS. 1 and 2.
FIG. 1 is a schematic configuration diagram showing a nuclear power plant of this example.

  In this example, an improved boiling water reactor (ABWR) is applied as a nuclear power plant. As shown in FIG. 1, a nuclear power plant 1 includes a reactor containment vessel 2, a reactor pressure vessel 3, a reactor core 4, an isolation wall 5, a pedestal 7, a suppression chamber 8, a cooling mechanism 10, and the like. I have. Further, the nuclear power plant 1 includes a gas discharge pipe 18 and a static catalytic hydrogen recombination device 17.

  The reactor pressure vessel 3 is formed in a substantially cylindrical shape by a steel material such as stainless steel. A reactor core 4 loaded with a plurality of fuel assemblies is disposed inside the reactor pressure vessel 3. Further, reactor water 3a is supplied into the reactor pressure vessel 3 as a reactor coolant and a moderator. The reactor pressure vessel 3 is connected to a main steam pipe 12 and a water absorption pipe (not shown). The main steam line 12 is provided with a main steam isolation valve 12a. The reactor pressure vessel 3 is supported by the pedestal 7 and accommodated in the reactor containment vessel 2.

  The reactor containment vessel 2 of this example is made of steel having a thermal conductivity higher than that of concrete. The reactor containment vessel 2 is formed in a cylindrical shape so as to have airtightness. A reactor pressure vessel 3 and a suppression chamber 8 are stored in the reactor containment vessel 2.

  Furthermore, the internal space of the reactor containment vessel 2 is divided by a pedestal 7 that supports the reactor pressure vessel 3 and a diaphragm floor 6 that is an airtight wall. Specifically, the internal space of the reactor containment vessel 2 is divided into an upper dry well 2a, a lower dry well 2b, and a suppression chamber 8 which are gas phase portions by a diaphragm floor 6. The upper dry well 2 a is a space above the diaphragm floor 6, and the lower dry well 2 b and the suppression chamber 8 are spaces below the diaphragm floor 6.

  The pedestal 7 is formed in a substantially cylindrical shape. The pedestal 7 is erected upward from the floor surface formed at the bottom of the reactor containment vessel 2. The upper end of the pedestal 7 is joined to the diaphragm floor 6 and supports the reactor pressure vessel 3.

  The pedestal 7 divides the space below the diaphragm floor 6 in the internal space of the reactor containment vessel 2 into a lower dry well 2 b and a suppression chamber 8. The space of the wall surface of the pedestal 7 and the reactor containment vessel 2 becomes a suppression chamber 8. The suppression chamber 8 is filled with pressure suppression water 8b for suppressing the pressure in the reactor containment vessel 2. And the upper space part 8a used as a gaseous-phase part is formed in the upper part of the pressure suppression water 8b of the suppression chamber 8. FIG.

  A vent pipe 11 is provided on the diaphragm floor 6. The vent pipe 11 communicates the suppression chamber 8 and the upper dry well 2a. One end of the vent pipe 11 opens to the upper dry well 2a, and the other end of the vent pipe 11 opens in the pressure suppression water 8b filled in the suppression chamber 8.

  In an emergency, water vapor in the upper dry well 2 a passes through the vent pipe 11 and is released toward the pressure suppression water 8 b of the suppression chamber 8. The discharged water vapor is cooled and condensed by the pressure suppression water 8b of the suppression chamber 8.

  Furthermore, a vacuum break valve 14 is provided at the upper end of the pedestal 7. The vacuum breaker valve 14 communicates the upper space portion 8a in the suppression chamber 8 and the lower dry well 2b so as to be opened and closed. The vacuum break valve 14 is normally closed. When the pressure in the suppression chamber 8 becomes higher than the pressure in the lower dry well 2b, the vacuum break valve 14 is opened. Then, the gas in the upper space 8 a of the suppression chamber 8 is released to the lower dry well 2 b through the vacuum break valve 14.

  The inside of the reactor containment vessel 2 excludes oxygen by replacing air with nitrogen. This prevents the occurrence of a hydrogen explosion.

  The isolation wall 5 is installed so as to surround the outer wall of the reactor containment vessel 2 and spaced from the outer wall of the reactor containment vessel 2. The isolation wall 5 is made of, for example, concrete that shields radiation. A static cooling mechanism 10 is formed between the isolation wall 5 and the reactor containment vessel 2. The cooling mechanism 10 has a sealed structure in which the gas in the inner space is not leaked by the isolation wall 5 and the outer wall of the reactor containment vessel 2.

  The cooling mechanism 10 includes a cooling pool 15 filled with cooling water 15a and a cooling gas phase portion 16 formed above the cooling water 15a in the cooling pool 15. In the cooling gas phase section 16, air normally exists. A static catalytic hydrogen recombination device 17 is disposed in the cooling gas phase section 16. The static catalytic hydrogen recombining device 17 recombines hydrogen with oxygen contained in the air existing in the initial atmosphere in the cooling gas phase unit 16. Then, the static catalytic hydrogen recombining device 17 turns hydrogen into water vapor.

  Further, an exhaust line 13 is connected to the upper end of the isolation wall 5, that is, the cooling mechanism 10. The exhaust line 13 communicates the cooling gas phase section 16 with the outside of the reactor building. And the water vapor | steam in the cooling gas-phase part 16 passes the exhaust line 13, and is discharge | released outside.

  The cooling pool 15 is adjacent to the suppression chamber 8 with the outer wall of the reactor containment vessel 2 interposed therebetween. Therefore, the suppression chamber 8 can be efficiently cooled by the cooling pool 15. The cooling pool 15 and the suppression chamber 8 communicate with each other via a gas discharge pipe 18.

  The gas discharge pipe 18 has a gas discharge part 18a, a gas inflow part 18b, and a pipe part 18c. The gas discharge part 18 a is an opening formed at one end of the gas discharge pipe 18. The gas inflow portion 18 b is an opening formed at the other end of the gas discharge pipe 18. And the piping part 18c connects the gas discharge | release part 18a and the gas inflow part 18b.

  The gas discharge part 18 a is disposed in the cooling water 15 a of the cooling pool 15. The gas inflow portion 18 b is disposed in the upper space portion 8 a of the suppression chamber 8. The piping portion 18 c passes through the upper space portion 8 a of the suppression chamber 8 and penetrates the outer wall of the reactor containment vessel 2. The piping portion 18 c extends from the outer wall of the reactor containment vessel 2 through the cooling gas phase portion 16 and into the cooling water 15 a of the cooling pool 15.

  The direction in which the piping portion 18c extends is not limited to the above-described example. For example, the pipe portion 18 c may be passed through the pressure suppression water 8 b from the upper space portion 8 a of the suppression chamber 8 and extended into the cooling water 15 a of the cooling pool 15.

  Further, it is desirable that the gas discharge part 18 a be disposed near the bottom surface of the cooling pool 15. Thereby, the cooling water 15a of the cooling pool 15 can be agitated by the gas S2 made of water vapor or hydrogen discharged from the gas discharge portion 18a. As a result, temperature stratification in which the temperature of the cooling water 15a in the cooling pool 15 forms a layer can be prevented, and the heat removal capability of the reactor containment vessel 2 by the cooling pool 15 can be increased.

  Further, it is desirable that the gas inflow portion 18 b is disposed above the upper space portion 8 a of the suppression chamber 8. Thereby, it is possible to prevent the gas inflow portion 18b from being submerged in the pressure suppression water 8b of the suppression chamber 8. A filter 19 is provided in the gas inflow portion 18b.

FIG. 2 is a perspective view showing the gas inflow portion 18 b of the gas discharge pipe 18.
As shown in FIG. 2, the gas inflow part 18b is provided with a filter 19 and an activation valve 19a. The start valve 19a is disposed closer to the opening side of the gas inflow portion 18b than the filter 19 is. The start valve 19a is constituted by, for example, a rupture disk or a safety valve that opens at a predetermined pressure. Therefore, the activation valve 19a does not require a power source or an operator's operation during the opening operation. Thereby, the starting malfunction resulting from valve operation, pump operation, etc. can be eliminated, and the reactor containment vessel 2 can be depressurized without the operation of the power source or the operator.

  The filter 19 is disposed so as to block the passage of the gas inflow portion 18b. And the filter 19 permeate | transmits hydrogen and water vapor | steam, and does not permeate | transmit a radioactive substance. Here, the molecular diameter of hydrogen or water vapor to be permeated is 0.3 nm, which is a fission generation part generated in the furnace, and is also a radioactive substance such as iodine, cesium, or a radioactive noble gas (mainly krypton or xenon). The molecular diameter is greater than 0.3 nm. Therefore, the filter 19 is constituted by, for example, a molecular sieving film that uses the principle of molecular sieving that selectively transmits a gas smaller than a predetermined molecular diameter.

  In the case of the improved boiling water light water reactor, the gas in the reactor containment vessel 2 is replaced with nitrogen. Therefore, when a gas is selectively permeated through a molecular sieve membrane, there is a possibility that nitrogen having a molecular diameter close to that of krypton or xenon will not permeate. However, from the viewpoint of depressurizing the reactor containment vessel 2, there is no problem even if nitrogen does not pass through the filter 19.

  As the filter 19 having such a configuration, for example, gas separation is performed by molecular sieve such as a polymer film mainly composed of polyimide, a ceramic film mainly composed of silicon nitride, or a graphene oxide film mainly composed of carbon. Is used. Note that the filter 19 is not limited to the above-described one, and any filter that does not transmit the fission product generated in the furnace and transmits hydrogen and water vapor may be used.

1-2. Next, the cooling operation of the reactor containment vessel 2 when an accident occurs in the nuclear power plant 1 having the above-described configuration will be described. A case where a major break (large LOCA) occurs in the main steam pipe 12 will be described.

  As shown in FIG. 1, when a rupture occurs in the main steam pipe 12, water vapor generated in the reactor pressure vessel 3 flows out from the rupture port K <b> 1 of the main steam pipe 12. Therefore, the water level and pressure of the reactor water 3a in the reactor pressure vessel 3 are reduced. The main steam isolation valve 12 a provided in the main steam pipe 12 is closed by a signal indicating the flow rate of water vapor passing through the main steam pipe 12. Then, water vapor and other radioactive substances are prevented from flowing out of the reactor containment vessel 2.

  A scram signal is generated by a signal indicating that the main steam isolation valve 12a is closed. And by this scram signal, all the control rods are inserted into the core 4 and the nuclear reactor is stopped.

  Even after the reactor is stopped, decay heat is generated in the reactor pressure vessel 3. And although it is as small as several percent or less of the rated heat output and decreases exponentially with time, water vapor continues to be generated by this decay heat. Therefore, the reactor water 3a in the reactor pressure vessel 3 is also reduced. For this reason, it is necessary to cool the core 4 continuously by maintaining the water level in the reactor pressure vessel 3. Furthermore, by condensing water vapor generated in the reactor core 4, it is necessary to reduce the rise in pressure in the reactor containment vessel 2 and remove decay heat from the reactor containment vessel 2.

First, condensation of generated water vapor will be described.
The water vapor that has flowed into the upper dry well 2a from the breaking port K1 of the main steam pipe 12 flows into the pressure suppression water 8b of the suppression chamber 8 through the vent pipe 11. And the water vapor | steam contained in gas S1 which flowed in in the pressure suppression water 8b is condensed by the pressure suppression water 8b, and is returned to water. Thereby, it can suppress that the pressure in the reactor containment vessel 2 rises with the generated water vapor.

Next, maintenance of the water level of the reactor water 3a in the reactor pressure vessel 3 and heat removal from the reactor containment vessel 2 will be described.
Even when a large LOCA occurs, if an external power supply or an emergency power supply is available, water is injected into the reactor pressure vessel 3 by an emergency core cooling system (ECCS). Thereby, the water level of the reactor water 3a can be maintained above the reactor core 4, and the reactor core 4 can be continuously cooled.

  Moreover, the temperature of the pressure suppression water 8b of the suppression chamber 8 rises by condensing the water vapor. However, the pressure suppression water 8b of the suppression chamber 8 is cooled by the residual heat removal system (RHR), and heat removal from the reactor containment vessel 2 is performed. Moreover, the reactor containment vessel 2 can be cooled by injecting cooling water into the space in the reactor containment vessel 2 using RHR. Thereby, large LOCA can be safely converged.

  Note that when the external power supply or the emergency power supply cannot be used, the above-described RHR heat removal function cannot be used. Therefore, the water temperature of the pressure suppression water 8b of the suppression chamber 8 may increase and the pressure of the reactor containment vessel 2 may increase. Furthermore, when water injection by ECCS fails, there is a possibility that the fuel cladding provided in order to prevent the radioactive material released from the nuclear fuel from leaking to the outside becomes hot and damaged. Then, when Zircairo contained in the fuel cladding tube in which water or water vapor becomes high temperature, hydrogen is generated. The generated hydrogen flows out from the breaking opening K1 to the upper dry well 2a together with water vapor. Further, the hydrogen passes through the vent pipe 11 together with the water vapor and flows into the suppression chamber 8.

  Oh, the nuclear power plant 1 of this example can cool the reactor containment vessel 2 statically, assuming the accident that the power source is lost. Next, the operation of statically cooling the reactor containment vessel 2 will be described.

  When the water temperature of the pressure suppression water 8b of the suppression chamber 8 rises, the heat of the pressure suppression water 8b is radiated to the cooling water 15a of the cooling pool 15 in the cooling mechanism 10 through the outer wall of the reactor containment vessel 2. As a result, the pressure suppression water 8b of the suppression chamber 8 is cooled and the cooling water 15a of the cooling pool 15 is heated.

  When the pressure in the upper space 8a of the suppression chamber 8 rises and reaches a predetermined pressure, the start valve 19a (see FIG. 2) provided in the gas inflow portion 18b of the gas discharge pipe 18 is opened. Further, since the cooling gas phase portion 16 is connected to the outside of the reactor building via the exhaust line 13, the pressure of the cooling gas phase portion 16 of the cooling mechanism 10 is equal to the atmospheric pressure. Therefore, since the pressure of the upper space portion 8a of the suppression chamber 8 is higher than the pressure of the cooling gas phase portion 16, the gas in the upper space portion 8a enters the cooling water 15a of the cooling pool 15 via the filter 19 and the gas discharge pipe 18. Released.

  The radioactive substance contained in the gas in the upper space 8 a is blocked by the filter 19. Therefore, the gas S2 discharged from the gas discharge portion 18a of the gas discharge pipe 18 includes water vapor and hydrogen, and does not include a radioactive substance. As a result, it is possible to prevent the radioactive material from leaking out of the reactor containment vessel 2.

  The water vapor contained in the gas S2 discharged from the gas discharge pipe 18 to the cooling water 15a is directly discharged into the cooling water 15a of the cooling pool 15. And the water vapor | steam contained in gas S2 is cooled in the cooling water 15a of the cooling pool 15, and is condensed. The cooling water 15a of the cooling pool 15 is heated by the condensation heat generated with this condensation.

  Moreover, since the cooling water 15a is heated in a state of being in direct contact with the water vapor, the heating efficiency of the cooling water 15a can be improved as compared with heating by heat transfer from a wall surface or piping. Therefore, the cooling water 15a of the cooling pool 15 quickly reaches 100 ° C., which is the saturation temperature at atmospheric pressure, and boils.

  By boiling the cooling water 15a, the heat transfer form from the cooling water 15a through the outer wall of the reactor containment vessel 2 to the pressure suppression water 8b of the suppression chamber 8 shifts from convection heat transfer to boiling heat transfer. Boiling heat transfer has a heat transfer rate 10 times greater than convective heat transfer. Therefore, the heat transfer efficiency by the cooling water 15a is improved, and the reactor containment vessel 2 can be efficiently removed.

  In addition, hydrogen is also contained in gas S2 discharged | emitted by the cooling water 15a. And since hydrogen is not condensed, it moves from the cooling pool 15 to the cooling gas phase section 16. The hydrogen moved to the cooling gas phase section 16 is combined with oxygen existing in the initial atmosphere in the cooling gas phase section 16 by the static catalytic hydrogen recombination device 17 and becomes water vapor. Then, the water vapor is released to the outside of the reactor building through the exhaust line 13. Thereby, it is possible to prevent a hydrogen explosion from occurring. In order to prevent the released hydrogen and water vapor from re-entering the reactor building, it is preferable that the exhaust line 13 can release hydrogen and water vapor to the external environment of the reactor building.

  Moreover, although the example which has arrange | positioned the static catalytic hydrogen recombination apparatus 17 in the cooling gas phase part 16 was demonstrated in this example, it is not limited to this. The static catalytic hydrogen recombining device 17 may be installed in the exhaust line 13. The cooling gas phase section 16 is filled with water vapor generated from the cooling water 15a. Therefore, even if the static catalytic hydrogen recombining device 17 is not provided, the probability that a hydrogen explosion will occur is small.

  Thus, according to the nuclear power plant 1 of this example, the nuclear reactor 1 is a completely static method using the cooling mechanism 10 without using a dynamic method such as valve operation or pump activation by an operator. The containment vessel 2 can be cooled. Furthermore, the cooling water 15a can be efficiently heated and boiled early, and the heat removal effect of the reactor containment vessel 2 can be enhanced.

  Further, since hydrogen generated together with water vapor can be released to the outside of the reactor containment vessel 2 through the gas release pipe 18, it is possible to suppress an increase in the pressure of the reactor containment vessel 2 due to hydrogen. Moreover, it is possible to prevent the radioactive material from leaking out of the reactor containment vessel 2 by the filter 19 that allows hydrogen and water vapor to pass therethrough and does not allow the radioactive material to pass therethrough. As a result, a highly safe nuclear power plant 1 can be provided.

2. Second Embodiment Next, a nuclear power plant according to a second embodiment will be described with reference to FIG.
FIG. 3 is a schematic configuration diagram showing a nuclear power plant according to the second embodiment.

  The nuclear power plant according to the second embodiment differs from the nuclear power plant 1 according to the first embodiment in the configuration of a nuclear containment vessel, a static cooling mechanism, and a gas discharge pipe. . Therefore, here, the nuclear containment vessel, the cooling mechanism, and the gas discharge pipe will be described, and the portions common to the nuclear power plant according to the first embodiment will be denoted by the same reference numerals and redundant description will be omitted. To do.

  As shown in FIG. 3, the nuclear power plant 20 includes a reactor containment vessel 2B, a reactor pressure vessel 3, a core 4, a pedestal 7, a suppression chamber 8, a cooling mechanism 21, a gas discharge pipe 28, and the like. It has.

  The reactor containment vessel 2 </ b> B stores a reactor pressure vessel 3, a pedestal 7, and a suppression chamber 8. Further, the reactor containment vessel 2B is formed of, for example, concrete that blocks radiation. Further, a containment vessel upper lid 2c is provided on the upper portion of the reactor containment vessel 2B.

  The cooling mechanism 21 is installed above the reactor containment vessel 2B. Further, the cooling mechanism 21 has a sealed structure in which the internal gas does not leak to other sections of the reactor building (not shown). The cooling mechanism 21 has a cooling pool 22 filled with cooling water 22a and a cooling gas phase section 23 formed above the cooling water 22a in the cooling pool 22. The water surface position of the cooling water 22a filled in the cooling pool 22 is higher than the reactor containment vessel 2B.

  An exhaust line 27 is connected to the cooling mechanism 21. One end portion of the exhaust line 27 is connected to the cooling gas phase portion 23 of the cooling mechanism 21, and the other end portion of the exhaust line 27 extends to the outside of the reactor building. Therefore, the exhaust line 27 communicates the cooling gas phase section 23 with the outside of the reactor building. And the water vapor | steam in the cooling gas-phase part 23 passes the exhaust line 27, and is discharge | released outside. Further, a static catalytic hydrogen recombination device 17 is disposed in the cooling gas phase section 23.

  The cooling mechanism 21 includes a heat exchanger 24 disposed in the cooling pool 22, a condensed water discharge pipe 25, and a gas supply pipe 26. One end of the condensed water discharge pipe 25 is connected to the lower end of the heat exchanger 24. The other end of the condensed water discharge pipe 25 is disposed in the pressure suppression water 8 b of the suppression chamber 8.

  One end of the gas supply pipe 26 penetrates the containment vessel upper lid 2c of the reactor containment vessel 2B and is disposed in the upper dry well 2a. The other end of the gas supply pipe 26 is connected to the upper end of the heat exchanger 24.

  The gas in the upper dry well 2 a is supplied to the heat exchanger 24 through the gas supply pipe 26. The water vapor contained in the gas supplied to the heat exchanger 24 is condensed by passing through the heat exchanger 24. The condensed water vapor is discharged to the pressure suppression water 8b of the suppression chamber 8 through the condensed water discharge pipe 25.

  Further, the gas discharge pipe 28 has a gas discharge part 28a, a gas inflow part 28b, and a pipe part 28c. The gas discharge part 28 a is an opening formed at one end of the gas discharge pipe 28. The gas inflow portion 28 b is an opening formed at the other end of the gas discharge pipe 28. And the piping part 28c connects the gas discharge | emission part 28a and the gas inflow part 28b.

  The gas discharge unit 28 a is disposed in the cooling water 22 a of the cooling pool 22. The gas inflow portion 28 b is disposed in the upper space portion 8 a of the suppression chamber 8. As a result, the upper space 8 a of the suppression chamber 8 and the cooling pool 22 communicate with each other through the gas discharge pipe 28. Further, the gas inflow portion 28b is provided with a filter 19 and a start valve (not shown).

  As described above, the water surface position of the cooling water 22a filled in the cooling pool 22 is higher than the reactor containment vessel 2B. Therefore, when the pressure in the upper space 8 a of the suppression chamber 8 is about atmospheric pressure during normal operation, the cooling water 22 a of the cooling pool 22 may flow back to the filter 19 through the gas discharge pipe 28. Therefore, the backflow prevention part 28d is provided in the pipe part 28c of the gas discharge pipe 28.

  The backflow prevention unit 28 d is disposed at a position sufficiently higher than the water surface position of the cooling water 22 a of the cooling pool 22. Thereby, it is possible to prevent the cooling water 22a from flowing back to the filter 19 through the gas discharge pipe 28. Instead of providing the backflow prevention part 28d, a check valve may be provided in the pipe part 28c.

  Next, a cooling operation when an accident (large LOCA) occurs in the nuclear power plant 20 according to the second embodiment having the above-described configuration will be described.

  When a large LOCA occurs, the pressure in the upper dry well 2 a becomes higher than the pressure in the suppression chamber 8. Therefore, the gas in the upper dry well 2 a is supplied to the heat exchanger 24 through the gas supply pipe 26. The water vapor contained in the gas supplied to the heat exchanger 24 is condensed by passing through the heat exchanger 24. The condensed water vapor returns to the pressure suppression water 8 b of the suppression chamber 8 through the condensed water discharge pipe 25.

  Further, when the pressure in the upper space portion 8a of the suppression chamber 8 of the suppression chamber 8 rises and reaches a predetermined pressure, the start valve provided in the gas inflow portion 28b of the gas discharge pipe 28 is opened. Therefore, the gas in the upper space 8 a of the suppression chamber 8 passes through the filter 19 and the gas discharge pipe 28 and is discharged to the cooling water 22 a of the cooling pool 22.

  And the cooling water 22a of the cooling pool 22 is heated by the gas discharge | released from the gas discharge part 28a of the gas discharge piping 28, and boils at an early stage. Thereby, the heat transfer efficiency by the cooling water 22a is improved, and the gas passing through the heat exchanger 24 can be efficiently removed.

  Further, hydrogen contained in the gas released from the gas release pipe 28 moves from the cooling pool 22 to the cooling gas phase unit 23. The hydrogen that has moved to the cooling gas phase section 23 is combined with oxygen existing in the initial atmosphere in the cooling gas phase section 23 by the static catalytic hydrogen recombination device 17 and becomes water vapor. Then, water vapor is discharged to the outside from an exhaust line 27 connected to the cooling mechanism 21.

  Since other configurations are the same as those of the nuclear power plant 1 according to the first embodiment, the description thereof is omitted. Also with the nuclear power plant 20 having such a configuration, the same operational effects as those of the nuclear power plant 1 according to the first embodiment described above can be obtained.

3. Third Embodiment Next, a nuclear power plant according to a third embodiment will be described with reference to FIG.
FIG. 4 is a schematic configuration diagram showing a nuclear power plant according to a third embodiment.

  The nuclear power plant according to the third embodiment differs from the nuclear power plant 1 according to the first embodiment in the configuration of a nuclear containment vessel, a static cooling mechanism, and a gas discharge pipe. . Therefore, here, the nuclear containment vessel, the cooling mechanism, and the gas discharge pipe will be described, and the portions common to the nuclear power plant according to the first embodiment will be denoted by the same reference numerals and redundant description will be omitted. To do.

  As shown in FIG. 4, the nuclear power plant 30 includes a reactor containment vessel 2B, a reactor pressure vessel 3, a core 4, a pedestal 7, a suppression chamber 8, a cooling mechanism 31, a gas discharge pipe 38, and the like. It has.

  The reactor containment vessel 2B has the same configuration as the reactor containment vessel 2B according to the second embodiment. And the containment vessel upper cover 2c is provided in the upper part of the reactor containment vessel 2B. The storage container upper lid 2c is made of steel having a higher thermal conductivity than concrete.

  The cooling mechanism 31 is disposed on the upper part of the reactor containment vessel 2B, and a part thereof is in contact with the containment vessel upper lid 2c. The cooling mechanism 31 includes a cooling pool 32 filled with cooling water 32 a and a cooling gas phase portion 33 formed above the cooling water 32 a in the cooling pool 32. A static catalytic hydrogen recombination device 17 is disposed in the cooling gas phase section 33.

  An exhaust line 37 is connected to the cooling mechanism 31. One end portion of the exhaust line 37 is connected to the cooling gas phase portion 33 of the cooling mechanism 31, and the other end portion of the exhaust line 37 extends to the outside of the reactor building. Therefore, the exhaust line 37 communicates the cooling gas phase portion 33 with the outside of the reactor building. And the water vapor | steam in the cooling gas-phase part 33 passes the exhaust line 37, and is discharge | released outside.

  A part of the bottom surface of the cooling pool 32 is formed by the containment vessel upper lid 2c of the reactor containment vessel 2B. Therefore, the cooling water 32a filled in the cooling pool 32 directly contacts the storage container upper lid 2c. The cooling mechanism 31 directly cools the upper dry well of the reactor containment vessel 2B through the containment vessel upper lid 2c.

  The gas discharge pipe 38 has a gas discharge part 38a, a gas inflow part 38b, and a pipe part 38c. The gas discharge part 38 a is arranged in the cooling water 32 a of the cooling pool 32. Further, the gas inflow portion 38 b is disposed in the upper space portion 8 a of the suppression chamber 8. As a result, the upper space 8 a of the suppression chamber 8 and the cooling pool 32 communicate with each other through the gas discharge pipe 38. Further, the gas inflow portion 38b is provided with a filter 19 and a start valve (not shown).

  As described above, the water surface position of the cooling water 32a filled in the cooling pool 32 is higher than the reactor containment vessel 2B. Therefore, the backflow prevention part 38d is provided in the pipe part 38c of the gas discharge pipe 38 according to the third embodiment, similarly to the gas discharge pipe 28 according to the second embodiment.

  The backflow prevention unit 38d is disposed at a position sufficiently higher than the water surface position of the cooling water 32a of the cooling pool 32. Thereby, it is possible to prevent the cooling water 32a from flowing back to the filter 19 through the gas discharge pipe 38. Instead of providing the backflow prevention part 38d, a check valve may be provided in the pipe part 38c.

  Since other configurations are the same as those of the nuclear power plant 1 according to the first embodiment, the description thereof is omitted. Also with the nuclear power plant 30 having such a configuration, the same operational effects as those of the nuclear power plant 1 according to the first embodiment described above can be obtained.

4). Fourth Embodiment Next, a nuclear power plant according to a fourth embodiment will be described with reference to FIG.
FIG. 5 is a schematic configuration diagram showing a nuclear power plant according to a fourth embodiment.

  The nuclear power plant according to the fourth embodiment differs from the nuclear power plant 1 according to the first embodiment in the position of the gas inflow portion of the gas discharge pipe. Therefore, here, the gas discharge pipe will be described, and portions common to those of the nuclear power plant according to the first embodiment will be denoted by the same reference numerals and redundant description will be omitted.

  As shown in FIG. 5, the gas inflow portion 18 b of the gas discharge pipe 18 is disposed in the upper dry well 2 a of the reactor containment vessel 2. Therefore, the upper dry well 2 a and the cooling water 15 a of the cooling pool 15 communicate with each other via the gas discharge pipe 18. Further, the gas inflow portion 18b is provided with a filter 19 and a start valve (not shown). When the pressure of the upper dry well 2a reaches a predetermined pressure due to hydrogen or water vapor generated in the reactor core 4, the start valve is opened, and the gas in the upper dry well 2a passes through the filter 19 and the gas discharge pipe 18, passes through the cooling pool. Fifteen cooling water 15a is discharged.

  When large LOCA etc. generate | occur | produce, the pressure of the upper dry well 2a becomes higher than the pressure of the upper space part 8a of the suppression chamber 8. FIG. Therefore, the amount of hydrogen and water vapor passing through the filter 19 and the gas discharge pipe 18 is larger when the gas inflow portion 18b is disposed in the upper dry well 2a than when the gas inflow portion 18b is disposed in the upper space portion 8a. Therefore, in the nuclear power plant 40 according to the fourth embodiment, the cooling water 15a of the cooling pool 15 can be boiled earlier than the nuclear power plant 1 according to the first embodiment. As a result, the cooling effect can be improved as compared with the nuclear power plant 1 according to the first embodiment, and further, the pressure increase in the reactor containment vessel 2 due to hydrogen can be suppressed.

  Further, by disposing the gas inflow portion 18 b in the upper dry well 2 a above the diaphragm floor 6, the gas inflow portion 18 b can be prevented from being submerged in the pressure suppression water 8 b of the suppression chamber 8.

  Note that the fourth embodiment is also applied to the gas inflow portion 28b of the gas discharge pipe 28 according to the second embodiment and the gas inflow portion 38b of the gas discharge pipe 38 according to the third embodiment. Similarly to the gas discharge pipe 18, the upper dry well 2 a may be disposed.

  Since other configurations are the same as those of the nuclear power plant 1 according to the first embodiment, the description thereof is omitted. Also with the nuclear power plant 40 having such a configuration, the same operational effects as those of the nuclear power plant 1 according to the first embodiment described above can be obtained.

  The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the spirit of the invention described in the claims.

  For example, in the nuclear power plants 1, 20, and 30 according to the first embodiment, the second embodiment, and the third embodiment described above, an example in which the start valve is provided in the gas discharge pipe. Although demonstrated, it is not limited to this, It is not necessary to provide a starting valve.

  DESCRIPTION OF SYMBOLS 1, 20, 30, 40 ... Nuclear power plant, 2, 2B ... Reactor containment vessel, 2a ... Upper dry well (gas phase part), 2b ... Lower dry well, 2c ... Upper containment vessel cover, 3 ... Reactor pressure vessel 3a ... Reactor water, 4 ... Reactor core, 5 ... Isolation wall, 6 ... Diaphragm floor, 7 ... Pedestal, 8 ... Suppression chamber, 8a ... Upper space part (gas phase part), 8b ... Pressure suppression water, 10, 21 31 ... Cooling mechanism, 11 ... Vent pipe, 12 ... Main steam pipe, 12a ... Main steam isolation valve, 13, 27 ... Exhaust line, 14 ... Vacuum break valve, 15, 22, 32 ... Cooling pool, 15a, 22a, 32a ... Cooling water 16, 23, 33 ... Cooling gas phase part, 17 ... Static catalytic hydrogen recombination device, 18, 28, 38 ... Gas release pipe, 18a ... Gas release part, 18b ... Gas Inflow part, 18c ... piping part, 19 ... filter, 19a ... start valve, 24 ... heat exchanger, 25 ... condensed water discharge pipe, 26 ... gas supply pipe

Claims (7)

A reactor containment vessel containing a reactor pressure vessel;
A cooling mechanism having a cooling pool filled with cooling water, and cooling the reactor containment vessel;
A gas discharge pipe communicating the gas phase part of the reactor containment vessel and the cooling pool of the cooling mechanism;
A filter that is provided in the gas discharge pipe, transmits water vapor and hydrogen, and does not transmit radioactive substances;
Nuclear power plant equipped with. An isolation wall set around the outer wall of the reactor containment vessel so as to surround the outer wall of the reactor containment vessel,
The nuclear power plant according to claim 1, wherein the cooling mechanism is formed between the reactor containment vessel and the isolation wall. A suppression chamber that is stored in the reactor containment vessel and suppresses the pressure in the reactor containment vessel;
The nuclear power plant according to claim 2, wherein the cooling pool of the cooling mechanism is adjacent to the suppression chamber through an outer wall of the reactor containment vessel. The cooling mechanism is
A heat exchanger disposed in the cooling pool;
A gas supply pipe for connecting the heat exchanger and the reactor containment vessel, and supplying gas from the reactor containment vessel to the heat exchanger;
The nuclear power plant according to claim 1, further comprising: a condensed water discharge pipe that connects the heat exchanger and the containment vessel and discharges water vapor condensed by the heat exchanger to the containment vessel. . The cooling mechanism is installed on top of the reactor containment vessel,
The nuclear power plant according to claim 1, wherein a part of the bottom surface portion of the cooling pool is formed by a containment vessel upper cover installed on an upper part of the reactor containment vessel. The gas discharge pipe has a gas discharge part formed at one end thereof, a gas inflow part formed at the other end, and a pipe part connecting the gas discharge part and the gas inflow part. ,
The filter is disposed in the gas inflow portion,
The nuclear power plant according to claim 1, wherein the gas inflow portion is provided with a start valve that opens at a predetermined pressure. The cooling mechanism has a sealed structure in which gas in the internal space does not leak,
The nuclear power plant according to claim 1, wherein an exhaust line that connects the internal space and the outside of the reactor building is connected to the cooling mechanism.

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