Floating nuclear power generation system

Abstract

This application discloses a floating nuclear power generation system that can utilize the advantages of a floating body for cooling a nuclear reactor. 【Solution means】A nuclear reactor, a turbine generator driven by steam generated by the heat of the nuclear reactor, a floating body on which the nuclear reactor and the turbine generator are arranged and moored at sea, and steam generated in the pressure vessel or the containment vessel where the nuclear reactor is located in an emergency is condensed by the cold heat of stored water and returned as condensate to the pressure vessel or the containment vessel, a condenser, a water storage section for storing stored water, the water storage section is set such that at least the bottom is lower than the draft line of the floating body, and a communication valve for directly or indirectly allowing water around the floating body to flow in is provided. It is a floating nuclear power generation system.

Description

Technical Field

[0001] The present invention relates to a floating nuclear power generation system.

Background Art

[0002] For nuclear power generation systems, not only the form of installation on land but also the floating form floating on the sea has been proposed (for example, refer to Patent Documents 1-3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When an atomic power generation system is floated on the sea, since the periphery of the floating body is surrounded by the sea, it is inherently an environment advantageous for cooling the nuclear reactor. However, the nuclear reactor is strictly protected by a containment vessel or the like to prevent the release of radioactive substances into the environment. Therefore, even if an atomic power generation system installed on land is directly floated on the sea, the advantage that the periphery of the floating body is surrounded by the sea cannot be utilized for cooling the nuclear reactor.

[0006] Therefore, the present application discloses a floating nuclear power generation system capable of utilizing the advantages of the floating body for cooling the nuclear reactor.

Means for Solving the Problems

[0007] To solve the above problems, in the present invention, a water storage section for storing stored water for condensing steam generated in a pressure vessel or a containment vessel where the nuclear reactor is located in an emergency and returning it to condensed water is set such that at least the bottom is lower than the draft line of the floating body, and a communication valve for directly or indirectly allowing water around the floating body to flow in is provided.

[0008] Specifically, the present invention includes a nuclear reactor, a turbine generator driven by steam generated by the heat of the nuclear reactor, a floating body on which the nuclear reactor and the turbine generator are arranged and moored on the sea, a condenser for condensing steam generated in a pressure vessel or a containment vessel where the nuclear reactor is located in an emergency with the cold heat of stored water and returning it as condensed water into the pressure vessel or the containment vessel, and a water storage section for storing stored water. The water storage section is set such that at least the bottom is lower than the draft line of the floating body, and a communication valve for directly or indirectly allowing water around the floating body to flow in is provided. It is a floating nuclear power generation system.

[0009] In the above floating nuclear power generation system, the bottom of the water storage section for storing stored water for condensing steam generated in a pressure vessel or a containment vessel where the nuclear reactor is located in an emergency and returning it to condensed water is set to be lower than the draft line of the floating body, and the water around the floating body is directly or indirectly Since a communication valve is provided for allowing water to flow in successively, even if the stored water in the water storage section decreases, it is possible to directly or indirectly allow the water around the floating body to flow into the water storage section simply by opening the communication valve. Therefore, it can be said that in such a floating nuclear power generation system, it is possible to utilize the advantages of the floating body for cooling the nuclear reactor.

[0010] Note that the floating body has at least a side ballast tank formed in the side portion of the floating body by a double hull structure, and the water storage section may have a first communication valve that communicates the inside of the water storage section with the side ballast tank as a communication valve. According to this, when the stored water in the water storage section decreases, it is possible to allow the ballast water in the side ballast tank to flow into the water storage section simply by opening the first communication valve. Therefore, it can be said that in such a floating nuclear power generation system, it is possible to utilize the advantages of the floating body for cooling the nuclear reactor.

[0011] Also, the water storage section may have a second communication valve that allows the water around the floating body to flow into the water storage section as a communication valve. According to this, when the stored water in the water storage section decreases, it is possible to directly allow the water around the floating body to flow into the water storage section simply by opening the second communication valve. Therefore, it can be said that in such a floating nuclear power generation system, it is possible to utilize the advantages of the floating body for cooling the nuclear reactor.

[0012] Also, the condenser may be installed at least at a position higher than the nuclear reactor in the floating body. According to this, since the condensed condensate in the condenser naturally flows down into the pressure vessel or the containment vessel, it is possible to continuously convert the steam generated in the pressure vessel or the containment vessel into condensate and continuously return it to the pressure vessel or the containment vessel.

Advantages of the Invention

[0013] In the above floating nuclear power generation system, it is possible to utilize the advantages of the floating body for cooling the nuclear reactor.

Brief Description of the Drawings

[0014]

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DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described. The following embodiments are one aspect of the present invention and do not limit the technical scope of the present invention.

[0016] <Overview of Equipment Layout> FIG. 1 is a schematic diagram showing the equipment layout of the floating nuclear power generation system 1 according to the embodiment. In FIG. 1(A), the layout of various equipment provided in the floating nuclear power generation system 1 is shown when viewed from above and in FIG. 1(B), the layout of various equipment provided in the floating nuclear power generation system 1 is shown when viewed from the side.

[0017] The floating nuclear power generation system 1 is a floating power generation system that can be floated on the sea. Therefore, the floating nuclear power generation system 1 includes a floating body 2. As can be seen from FIG. 1(A), the floating body 2 has a streamlined shape. However, the floating body 2 is not a ship intended for autonomous navigation on the sea. The floating body 2 floats in a moored state on the sea in order to transmit the power generated by the floating nuclear power generation system 1 to the land. And, in order to suppress the resistance against the tidal current, the floating body 2 floats on the sea with only one end in the longitudinal direction being moored and the other end not being moored. For this reason, the floating body 2 floats on the sea like being drifted by the current. That is, when the floating body 2 receives the tidal current, it floats on the sea in a posture where the moored part naturally faces the upstream side of the tidal current.

[0018] Since the floating body 2 is such a streamlined floating body, in the present embodiment, for convenience, the moored part in the longitudinal direction of the floating body 2 is referred to as the "bow side", and the unmoored part is referred to as the "stern side". Therefore, in FIG. 1, the left side of the paper surface is the "bow side", and the right side of the paper surface is the "stern side". Also, FIG. 1(B) shows the internal configuration of the floating nuclear power generation system 1 when viewed from the starboard side of the floating body 2.

[0019] In addition, in the present embodiment, a streamlined floating body 2 is exemplified, but the floating body 2 may be a non-streamlined floating body. As the floating body 2 used in the floating nuclear power generation system 1, for example, a cylindrical floating body having a circular shape in plan view, a rectangular parallelepiped floating body having a rectangular shape in plan view, or floating bodies of various other shapes may be used.

[0020] As shown in FIG. 1, the floating nuclear power generation system 1 includes a nuclear reactor 3 disposed near the central portion of the floating body 2, and a turbine generator 4 disposed on the bow side of the nuclear reactor 3. The nuclear reactor 3 generates steam by boiling water with the heat generated by nuclear fission. The turbine generator 4 generates electricity by rotating the generator with a steam-driven turbine. In the present embodiment, a floating nuclear power generation system 1 of a boiling water reactor (BWR) that drives the turbine generator 4 with the steam of the nuclear reactor 3 is exemplified, but the floating nuclear power The power system 1 may be, for example, a pressurized water reactor (PWR), or it may use various other systems.

[0021] In addition to the floating body 2, reactor 3, and turbine generator 4 described above, the floating nuclear power generation system 1 is equipped with various types of equipment. The floating nuclear power generation system 1 includes, for example, reactor equipment areas 5, 7, a pit 6, and a fuel pool 8 around the reactor 3. Also, the floating nuclear power generation system 1 includes a desalination device 9, an IC / PCCS pool 10, various equipment areas 12, a living area 13, and a waste treatment room 24 arranged on the stern side of the reactor 3. Further, the floating nuclear power generation system 1 includes a condensate storage tank 14 arranged between the reactor 3 and the turbine generator 4. Additionally, the floating nuclear power generation system 1 includes a radar down area 18 and an auxiliary equipment area 19 arranged near the bow of the floating body 2. The auxiliary equipment area 19 is provided with a main transformer 20 and an auxiliary boiler 21. Also, the floating nuclear power generation system 1 includes a light oil tank 23 on the deck near the bow of the floating body 2. Moreover, the floating nuclear power generation system 1 is equipped with a bow ballast tank 25, a bottom ballast tank 26, a stern ballast tank 27, and side ballast tanks 28 for controlling the attitude of the floating body 2.

[0022] In the reactor equipment areas 5, 7, various reactor equipment installed outside the containment vessel of the reactor 3 is arranged. Examples of the equipment arranged in the reactor equipment areas 5, 7 include pumps and valves for various reactor cooling equipment such as an emergency core cooling system and a residual heat removal system, pumps and valves for a pool water cooling system that cools the fuel pool, control compressed air equipment, ventilation and air conditioning equipment, an emergency diesel generator that serves as an emergency power source, a DC power supply system using a storage battery, and various other equipment.

[0023] ​​The pit 6 is a pit for temporarily placing various articles during regular inspections and refueling. Examples of articles placed in the pit 6 include, for example, a steam separator and a steam dryer disposed above the nuclear fuel in the reactor 3.

[0024] The fuel pool 8 is a pool for storing unused or spent nuclear fuel. The nuclear fuel of the reactor 3 is in the form of fuel assemblies. Therefore, the fuel pool 8 is provided with a rack for storing the fuel assemblies at an appropriate interval. In addition, a fuel exchanger for transferring the fuel assemblies between the reactor 3 and the fuel pool 8 is provided above the fuel pool 8.

[0025] The desalination device 9 is a device for desalinating seawater. Since the floating nuclear power generation system 1 is used in a floating state on the sea, it is not possible to obtain fresh water containing almost no salt from a river like a facility on land. Therefore, the floating nuclear power generation system 1 is equipped with a desalination device 9 for removing salt from seawater to desalinate it in order to secure reactor cooling water and other various types of water. As the desalination method of the desalination device 9, various methods such as the reverse osmosis membrane method and the evaporation method can be applied.

[0026] The IC / PCCS pool 10 houses the IC heat exchanger and the PCCS heat exchanger. The IC heat exchanger is a facility of the isolation condenser (IC), and cools the reactor 3 when a total loss of AC power occurs and the containment vessel becomes isolated. The PCCS heat exchanger is a facility of the passive containment cooling system (PCCS), and cools the steam released into the containment vessel during severe accidents and the like.

[0027] In various equipment areas 12, there are provided a central control room for operating and controlling the floating nuclear power generation system 1, an access control room for managing access to and from the radiation control area, and various other equipment. Incidentally, the aforementioned emergency diesel generators and DC power supply equipment may be provided in the various equipment areas 12 instead of the reactor equipment areas 5 and 7.

[0028] In the residential area 13, residential facilities for the residence of operators and others staying in the floating nuclear power generation system 1 are arranged. Examples of the residential facilities include private rooms equipped with beds and the like, a cafeteria equipped with cooking equipment and the like, bathing facilities, entertainment facilities, and various other facilities.

[0029] In the waste treatment room 24, various equipment for treating radioactive waste is arranged. Examples of the radioactive waste treated in the waste treatment room 24 include liquid waste such as waste liquid generated in the radiation control area, and miscellaneous solid waste such as waste materials generated during various operations. These wastes are volume-reduced in the waste treatment room 24 by evaporation concentration, compression, incineration, etc., stored in the floating body 2, and then carried out from the floating body 2.

[0030] The condensate storage tank 14 is a tank for storing water that can be supplied to the reactor 3. The condensate storage tank 14 is connected to the condenser of the turbine generator 4 and the emergency core cooling system, and is used for replenishing water to the condenser during normal operation and injecting water into the reactor 3 in case of emergency.

[0031] The laydown area 18 is a work space for disassembling and inspecting various large equipment such as the turbine generator 4. The laydown area 18 is a space on the same floor as the operating floor of the turbine generator 4, and large equipment can be easily transferred by the crane equipment installed above the operating floor.

[0032] In the auxiliary equipment area 19, various auxiliary equipments such as the main transformer 20 and the auxiliary boiler 21 are arranged. The main transformer 20 is a transformer for stepping up the electricity generated by the turbine generator 4 to the voltage of the power grid. The auxiliary boiler 21 is a boiler that generates steam with the heat generated by burning light oil.

[0033] The floating nuclear power generation system 1 is moored at sea by an anchor chain 22 provided on the bow side of the floating body 2. As described above, when the floating nuclear power generation system 1 is affected by the tidal current, the moored part floats on the sea in a posture naturally facing the upstream side of the tidal current. For this reason, the submarine cable for connecting the floating nuclear power generation system 1 and the onshore power grid is also suspended from near the bow of the floating body 2 toward the seabed, similar to the anchor chain 22. For this reason, it is reasonable that the main transformer 20 for stepping up the electricity generated by the turbine generator 4 to the voltage of the power grid is arranged near the bow of the floating body 2 close to the submarine cable, as shown in FIG. 1.

[0034] In addition, the auxiliary boiler 21 is used for the ground steam of the turbine generator 4, heating of the steam equipment around the turbine, etc. at the start of the floating nuclear power generation system 1. For this reason, it is also reasonable that the auxiliary boiler 21 is arranged near the turbine generator 4.

[0035] For this reason, the floating nuclear power generation system 1 adopts a form in which the main transformer 20 and the auxiliary boiler 21 are arranged in the auxiliary equipment area 19 provided on the bow side of the floating body 2. In addition, the floating nuclear power generation system 1 adopts a form in which a light oil tank 23 for storing the light oil supplied to the auxiliary boiler 21 is arranged above the auxiliary equipment area 19. Note that in the auxiliary equipment area 19, not only the main transformer 20 and the auxiliary boiler 21, but also, for example, switching equipment such as a circuit breaker (LS: Line Switch) for opening and closing the electrical connection between the submarine cable and the main transformer 20 may be installed.

[0036] The bow ballast tank 25, the bottom ballast tank 26, the stern ballast tank 27, and the side ballast tank 28 are tanks for receiving ballast water for controlling the attitude of the floating body 2. The ballast water in the bow ballast tank 25, the bottom ballast tank 26, and the stern ballast tank 27 can also be used as seawater for cooling the reactor 3 in the event of an emergency in the floating nuclear power generation system 1. The filling of the bow ballast tank 25, the bottom ballast tank 26, and the stern ballast tank 27 can be carried out naturally by the water pressure of seawater, for example, by opening a water intake provided at the bottom of the floating body 2 or the like. A pump or the like may be used in combination with the filling as necessary. Also, the drainage from the bow ballast tank 25, the bottom ballast tank 26, and the stern ballast tank 27 can be carried out by a pump or an ejector.

[0037] The above is an overview of the equipment layout of the floating nuclear power generation system 1 according to the present embodiment. However, the above-described equipment layout is an example, and other equipment layouts may be adopted. Next, an overview of the system configuration of the floating nuclear power generation system 1 will be described.

[0038] <Overview of System Configuration> FIG. 2 is a schematic diagram showing the system configuration of the floating nuclear power generation system 1 according to the embodiment. The floating nuclear power generation system 1 mainly consists of a reactor system R and a turbine system T. The aforementioned reactor 3 is the main equipment of the reactor system R. Also, the aforementioned turbine generator 4 is the main equipment of the turbine system T.

[0039] The reactor system R having the reactor 3 is equipped with various facilities such as a containment vessel 3A, nuclear fuel 3B, control rods 3C, a recirculation pump 3D, and a pressure vessel 3E. Also, the turbine system T having the turbine generator 4 is equipped with various facilities such as a turbine 4A and a generator 4B that constitute the turbine generator 4, as well as a condenser 4C, a circulating water pipe 4D, a circulating water pump 4E, and a feed water pump 4F.

[0040] The containment vessel 3A is a vessel that houses the pressure vessel 3E containing the nuclear fuel 3B and the like, and serves to confine the radioactive substances released from the pressure vessel 3E in the event of a meltdown accident in the nuclear reactor 3. The containment vessel 3A may be made of concrete or may be made of the steel material that constitutes the floating body 2. The containment vessel 3A encloses the pressure vessel 3E containing the nuclear reactor 3 at the center, and forms an upper drywell 3M above the pressure vessel 3E and a lower drywell 3N below the pressure vessel 3E. Further, the containment vessel 3A has a suppression pool 3H around the lower drywell 3N.

[0041] The pressure vessel 3E is a vessel that encloses the nuclear fuel 3B and the like, and serves to confine the water and steam for cooling the nuclear reactor 3. In the central part of the pressure vessel 3E, hundreds of nuclear fuels 3B are arranged in the form of fuel assemblies, thereby forming the main body of the nuclear reactor 3. In the main body of the nuclear reactor 3, a control rod 3C that can move up and down by a drive mechanism provided at the lower part of the pressure vessel 3E is inserted into the gaps between the fuel assemblies. When the control rod 3C is withdrawn from the nuclear reactor 3 and the nuclear reactor 3 becomes critical, the nuclear reactor 3 continuously generates heat. Further, when the control rod 3C is inserted into the nuclear reactor 3 and the nuclear reactor 3 becomes subcritical, the heat generation of the nuclear reactor 3 gradually attenuates.

[0042] The pressure vessel 3E is provided with a recirculation pump 3D. The recirculation pump 3D is responsible for heat removal from the nuclear reactor 3 and control of the nuclear reactor output by forcibly circulating the water, which is the nuclear reactor coolant, in the liquid phase part inside the pressure vessel 3E. In the floating nuclear power generation system 1 of this embodiment, since an advanced boiling water reactor (ABWR) is assumed, in FIG. 2, the recirculation pump 3D is shown in a form provided in the pressure vessel 3E, but the floating nuclear power generation system 1 is not limited to this. The floating nuclear power generation system 1 may have, for example, a recirculation system in which a recirculation pump and circulation pipes are arranged outside the pressure vessel 3E.

[0043] The pressure vessel 3E is connected to a main steam pipe 3L for sending the steam generated inside the pressure vessel 3E to the turbine generator 4 of the turbine system T. Since the main steam pipe 3L is a pipe connecting the inside and outside of the storage container 3A, main steam isolation valves 3J and 3K for isolating the storage container 3A are provided near the penetration part of the storage container 3A. And a relief safety valve 3F is provided in the middle of the main steam pipe 3L to prevent the internal pressure of the pressure vessel 3E from becoming excessive when the main steam isolation valves 3J and 3K are closed. The end of the exhaust pipe 3G on the downstream side of the relief safety valve 3F is arranged in the suppression pool 3H.

[0044] The turbine 4A and the generator 4B constituting the turbine generator 4 are connected by the same rotating shaft. The turbine 4A has a structure in which an impeller is housed in a casing. And a condenser 4C for condensing the steam that has passed through the turbine 4A is provided below the turbine 4A. A large number of thin pipes forming a part of the path of a circulating water pipe 4D connecting a water intake and a water discharge provided below the waterline of the outer surface of the floating body 2 are provided in the condenser 4C, and the steam is condensed by the cold heat of seawater pumped by a circulating water pump 4E provided on the path of the circulating water pipe 4D. For this reason, due to the pressure difference between the steam supplied from the reactor 3 through the main steam pipe 3L and the inside of the condenser 4C, power for rotating the generator 4B is applied to the impeller. Thereby, the generator 4B rotates and generates electricity. Also, the condensed water in the condenser 4C is fed again into the pressure vessel 3E via a feed water pipe 4G by a feed water pump 4F.

[0045] Note that Fig. 2 only shows the schematics of the reactor system R and the turbine system T, and actually, a wide variety of devices are provided. For example, important devices such as a steam control valve and a turbine bypass valve are provided near the turbine 4A of the main steam pipe 3L. The turbine bypass valve is rated The total amount of the main steam in the output may be 100% bypassable and directly sent to the condenser 4C without passing through the turbine 4A, or may have a bypass capacity below that. Also, important devices such as a feed water flow control valve, a condensate desalination device, and a feed water heater are provided in the feed water pipe 4G. Further, pipes of the emergency core cooling system and the like are provided inside and outside the storage container 3A. Also, the turbine 4A is a combination of a high-pressure turbine and a plurality of low-pressure turbines.

[0046] Also, in FIG. 2, only one system of each device is illustrated, but each device of the floating nuclear power generation system 1 is multiplexed. For example, a plurality of circulating water pumps 4E and feed water pumps 4F are provided.

[0047] In the reactor system R, the position of the control rod 3C is adjusted so that the reactor 3 maintains a predetermined reactor output. Also, in the turbine system T, the opening degree of the steam control valve is adjusted so that the turbine generator 4 maintains a predetermined rotational speed, and the feed water flow rate of the feed water pump 4F is adjusted so that the reactor 3 maintains a predetermined water level. By being configured in this way, the floating nuclear power generation system 1 transmits the thermal energy generated by the nuclear reaction of the reactor 3 as electrical energy to the power grid through the generator 4B synchronized with the system frequency.

[0048] The outline of the system configuration of the floating nuclear power generation system 1 according to the present embodiment is as described above. Next, the details of each characteristic part of the floating nuclear power generation system 1 will be described.

[0049] <Matters regarding the shape of the floating body 2> As described above, in the floating nuclear power generation system 1 according to the present embodiment, a streamlined floating body 2 is used. Since the floating nuclear power generation system 1 is used in a state of being moored at sea, the safety can be greatly improved by using the surrounding seawater to remove the decay heat of the reactor 3 stably for a long period of time.

[0050] As for floating nuclear power facilities on the ocean, for example, the Russian Akademik Lomonosov, which has a nuclear power plant installed on a ship-type version, started commercial operation in 2020. In Japan, a design to install a nuclear power plant on a flat-type floating body was also studied in the 1990s. However, nuclear power plants on ship-type or flat-type versions, like land-based nuclear power plants, have the reactor located at a position higher than the sea surface. Therefore, in order to use seawater for cooling the reactor in ship-type or flat-type version nuclear power plants, power such as electricity or an engine is required for pumping. For this reason, in order to maintain stable cooling for a long period, there is a problem in that replenishment of electricity and fuel from the outside is required.

[0051] As a design to overcome this problem, Professor Buongiorno of the Massachusetts Institute of Technology (hereinafter, "MIT") and others have devised a design in which a reactor system is incorporated into a cylindrical floating structure used for offshore oil drilling. However, in the cylindrical floating structure proposed by MIT, the reactor is arranged at the lower part and the steam turbine and generator are arranged at the upper part. And the steam turbine and generator are heavy objects. For this reason, it is difficult to realize a structure that supports such heavy objects at the upper part. In addition, since the cylindrical floating structure is substantially circular when viewed from above, when manufacturing in a horizontally long general shipbuilding dock, dead space is generated in the dock and the manufacturing efficiency is inferior. In addition, in a structure where the reactor is arranged at the lower part and the steam turbine and generator are arranged at the upper part, there are problems such as the draft becoming several times deeper than that of a large ship and the manufacturing becoming difficult.

[0052] Therefore, in the floating nuclear power generation system 1 of the present embodiment, a streamlined floating body 2 is adopted, and facilities for nuclear power generation such as a reactor 3 and a turbine generator 4 are arranged in the floating body 2 having a double hull structure similar to that of a large tanker. In the floating nuclear power generation system 1 of the present embodiment, as shown in FIG. 1(B), the reactor 3 is arranged below the sea surface. For this reason, in ship-type or flat-type versions It is possible to realize a passive heat exchange system for seawater that cannot be achieved in a single stage and does not require power such as electricity or an engine. Details of the passive heat exchange system realized by the floating nuclear power generation system 1 of the present embodiment will be described later.

[0053] Also, as described above, since the floating body 2 is moored by the anchor chain 22 at sea, it floats like a drift. FIG. 3 is a diagram showing how the floating body 2 changes direction. When the floating body 2 is affected by the tidal current, it floats on the sea in a posture where the bow moored by the anchor chain 22 naturally faces the upstream side of the tidal current. As a result, the streamlined floating body shape reduces resistance, so it is possible to suppress the tension applied to the anchor chain 22 as much as possible.

[0054] The advantages of the floating nuclear power generation system 1 by adopting the streamlined floating body 2 include several other aspects in addition to the relaxation of the resistance to the tidal current in the moored state as described above. For example, since the floating body 2 is streamlined, when manufacturing the floating nuclear power generation system 1 in a general horizontally long shipbuilding dock, the space in the dock can be utilized to the maximum extent, so the floating nuclear power generation system 1 can be manufactured efficiently. That is, in a shipbuilding dock, by using a plurality of cranes, for example, it is possible to carry out the manufacturing work near the reactor 3 and the manufacturing work near the turbine generator 4 simultaneously. Also, by manufacturing the floating nuclear power generation system 1 at a concentrated manufacturing base such as a shipbuilding dock, an improvement in manufacturing quality and a reduction in manufacturing cost can be expected. Since the floating nuclear power generation system 1 can be transported by sea, it can be easily exported to countries bordering the sea. Therefore, if the floating nuclear power generation system 1 manufactured at a concentrated manufacturing base is exported by sea transportation, it is superior in both quality and cost compared to the case of setting up manufacturing bases around the world.

[0055] In addition, other advantages of the floating nuclear power generation system 1 by adopting the streamlined floating body 2 include, for example, the ease of loading and unloading materials at sea. That is, in the case of the streamlined floating body 2, since the port side and the starboard side are generally linear, it is easy to moor other ships alongside the port side or the starboard side. If a ship can be moored alongside the port side or the starboard side of the floating body 2, it becomes possible to transfer the cargo while the linear sides are in contact with each other. For example, it is easy to transfer the food for the crew, the light oil consumed by the auxiliary boiler 21, the emergency diesel generator, etc., the chemicals used for water quality management, etc., the cask storing the nuclear fuel, and various other maintenance parts.

[0056] In addition, other advantages of the floating nuclear power generation system 1 by adopting the streamlined floating body 2 include, for example, the layout advantages of various facilities of the floating nuclear power generation system 1 such as the reactor 3 and the turbine generator 4. In the floating nuclear power generation system 1, the steam generated in the reactor 3 is sent to the turbine generator 4, and the electricity generated by the turbine generator 4 is transformed by the main transformer 20 and sent to the submarine cable. In the floating nuclear power generation system 1 where each facility cooperates in this way, it is more reasonable for devices such as the reactor 3, the turbine generator 4, and the main transformer 20 to be arranged in order. In this regard, in the case of the streamlined floating body 2, it is possible to arrange the reactor 3, the turbine generator 4, and the main transformer 20 in order from the stern to the bow. Also, in the case of the streamlined floating body 2, as shown in FIG. 2, the turbine generator 4 can be arranged so that the rotation axis is along the longitudinal direction of the floating body 2. Therefore, even if a turbine missile in which the turbine blade breaks during rotation should occur, the possibility of the turbine blade flying towards the reactor 3 can be eliminated. Note that in the floating nuclear power generation system 1, a casing with sufficient strength that does not allow the turbine blade to penetrate is adopted so that a turbine missile does not occur.

[0057] <Matters regarding the mooring of the floating body 2> Next, the characteristic matters provided in the floating nuclear power generation system 1 for mooring the streamlined floating body 2 will be described. Since the floating nuclear power generation system 1 adopts a form of mooring the streamlined floating body 2, it is equipped with a device for self-controlling the attitude of the floating body 2. Flo As a device for controlling the attitude of the floating body 2, for example, a thruster can be mentioned. If a thruster of an electric screw that can freely swivel in the propulsion direction is provided on the floating body 2, it is possible to freely change the direction of the floating body 2 around the mooring part or control the position of the floating body 2. Further, if a thruster is provided on the floating body 2, it becomes possible to continuously maintain the floating body 2 at a fixed point when the anchor chain 22 breaks.

[0058] Also, as a device for autonomously controlling the attitude of the floating body 2, for example, it is also possible to use the circulating water pump 4E. The circulating water pump 4E is a pump that supplies seawater to the condenser 4C, which has the largest cooling capacity among the facilities for nuclear power generation. Therefore, the circulating water pump 4E has the largest capacity among the pumps provided in the floating nuclear power generation system 1, and depending on the arrangement of the water intake and discharge ports of the circulating water pipe 4D, the floating body 2 can be moved on the sea. Thus, in the floating nuclear power generation system 1 of the present embodiment, as shown in FIG. 3, the circulating water pump 4EL provided in the circulating water pipe 4D connecting the water intake 4DSL on the port side and the water discharge port 4DHR on the starboard side pumps seawater from the port side to the starboard side, and the circulating water pump 4ER provided in the circulating water pipe 4D connecting the water intake 4DSR on the starboard side and the water discharge port 4DHL on the port side pumps seawater from the starboard side to the port side, and a circulating water system is provided. In normal times when the direction (attitude) of the floating body 2 is left to the tidal current, the water supply by the circulating water pump 4E is made symmetric by balancing the flow rate of the circulating water pump 4EL and the flow rate of the circulating water pump 4ER. And when it is desired to move the floating body 2 to the port side, the flow rate adjustment of the circulating water pipe 4D is performed so that the flow rate of the circulating water pump 4EL becomes larger than the flow rate of the circulating water pump 4ER. Also, when it is desired to move the floating body 2 to the starboard side, the flow rate adjustment of the circulating water pipe 4D is performed so that the flow rate of the circulating water pump 4ER becomes larger than the flow rate of the circulating water pump 4EL. The flow rate adjustment of the circulating water pipe 4D can be performed, for example, by adjusting the opening degree of the flow rate adjustment valve provided in the turbine generator 4, or by stopping the circulating water pump 4ER or the like. Such control of the direction of the floating body 2 by flow rate adjustment is effective not only for changing the direction around the mooring part but also for correcting the displacement of the floating body 2.

[0059] As a device for autonomously controlling the attitude of the floating body 2, in addition to the circulating water pump 4E, for example, the reactor auxiliary machine cooling seawater pump (RSW) for the reactor auxiliary machine cooling system (RCW: Reacter building Cooling Water system), the turbine auxiliary machine cooling system (TCW: Turbine building Cooling machine cooling seawater pump (RSW), the turbine auxiliary machine cooling system (TCW: Turbine building Cooling Examples of auxiliary cooling seawater pumps for the water system include the turbine auxiliary cooling seawater pump (TSW). In this embodiment In the floating nuclear power generation system 1, similar to the circulating water pump 4E, it is also possible to use the reactor auxiliary cooling seawater pump and the turbine auxiliary cooling seawater pump for position control. In the floating nuclear power generation system 1 of this embodiment, there are a plurality of reactor auxiliary cooling seawater pumps and turbine auxiliary cooling seawater pumps respectively. One seawater pump pumps seawater from the port side to the starboard side, and the other seawater pump pumps seawater from the starboard side to the port side. Therefore, if the flow rate of each seawater pump is adjusted according to the position of the floating body 2, it is possible to correct the displacement of the floating body 2.

[0060] Note that in the floating nuclear power generation system 1 of this embodiment, it is assumed that the turbine 4A has three low-pressure turbines. And for the three condensers 4C arranged below each low-pressure turbine, two sets of circulating water pipes 4D are connected to each for multiplexing. For this reason, in FIG. 3, six circulating water pipes 4D and the circulating water pumps 4E (4EL, 4ER) are shown. However, the floating nuclear power generation system 1 of this embodiment is not limited to this. The circulating water pipes 4D and the circulating water pumps 4E only need to be provided symmetrically. For example, there may be four or less, or eight or more. Also, in FIG. 3, the water intake 4DSL and the water discharge 4DHL are arranged close to each other. However, in order to suppress the short-circuit phenomenon, they may be arranged at a distance from each other, or may be provided so that the opening directions alternate, such as being on the side and below the floating body 2.

[0061] Another device for changing the direction of the floating body 2 includes a tugboat. Tug If the boat is constantly tied to the floating body 2, not only can the floating body 2 change its direction, but also, for example, when an emergency occurs in the sea area where the floating nuclear power generation system 1 is installed, the anchor chain 22 can be cut to quickly move the floating nuclear power generation system 1. Examples of emergencies that can occur in a specific sea area include, for example, the occurrence of natural disasters such as submarine volcano eruptions, and the occurrence of armed attacks by terrorists or the military. In addition, as measures to respond to armed attack situations targeting the floating nuclear power generation system 1, for example, it is desirable to set up an area to restrict the entry of ships and the like within a predetermined distance from the floating nuclear power generation system 1 to monitor maritime traffic, or to take measures such as setting up a mine defense network around the floating nuclear power generation system 1 to prevent the approach of torpedoes and suspicious ships.

[0062] When the floating body 2 can change its direction, for example, the following responses become possible. FIG. 4 is a diagram illustrating the state when a tsunami approaches the floating nuclear power generation system 1. FIG. 4(A) shows the floating nuclear power generation system 1 as viewed from above, and FIG. 4(B) shows the floating nuclear power generation system 1 as viewed from the side.

[0063] For example, as shown in FIG. 4(A), assume that the tidal current is flowing downward to the right in the plane of FIG. 4. In this case, the floating nuclear power generation system 1 moored by the anchor chain 22 floats in the state indicated by the reference symbol P1 in FIG. 4(A), that is, with the bow of the floating body 2 facing upward to the left, due to the tidal current. In this state, for example, assume that an earthquake or a typhoon centered on the left side in the plane of FIG. 4 occurs, and a tsunami flowing to the right is generated.

[0064] When the floating nuclear power generation system 1 receives this tsunami with the bow of the floating body 2 facing upward to the left, the floating nuclear power generation system 1 will receive the tsunami from the port side of the floating body 2. For this reason, the floating nuclear power generation system 1 may tilt to the starboard side due to the tsunami received from the port side of the floating body 2. On the other hand, if the generation of the tsunami is detected and the direction of the floating body 2 is immediately changed to the state shown by the reference symbol P2 in Fig. 4(A), that is, the state in which the bow of the floating body 2 faces left, the floating nuclear power generation system 1 will receive the tsunami from the bow side of the floating body 2. For this reason, the floating nuclear power generation system 1 can suppress as much as possible the possibility of tilting to either the port side or the starboard side of the floating body 2. Since the floating body 2 of the floating nuclear power generation system 1 is long from the bow to the stern, even if the floating nuclear power generation system 1 receives the tsunami from the bow side of the floating body 2, the floating nuclear power generation system 1 hardly tilts in the front-rear direction as shown in Fig. 4(B).

[0065] In addition, although in Fig. 4 the floating nuclear power generation system 1 is shown at a location relatively close to the land, it is preferable that the floating nuclear power generation system 1 is moored in the offing dozens of kilometers or more away from the land. As shown in Fig. 4(B) as well, tsunamis have the property of gradually increasing as they approach the shallow-water land. For this reason, if the floating nuclear power generation system 1 is moored in the deep offing dozens of kilometers or more away from the land, although it depends on the seabed topography, it is possible to make the magnitude of the tsunami received by the floating nuclear power generation system 1 relatively small.

[0066] The preferable distance from the land for mooring the floating nuclear power generation system 1 is, for example, 30 km or more. If the floating nuclear power generation system 1 is moored in the sea more than 30 km away from the land, there will be no residential areas within the evacuation plan formulation range required by Japanese law. In other words, it can be said that even if a large-scale accident occurs in the floating nuclear power generation system 1, it is almost impossible for the onshore residents to be in a situation where they need to evacuate.

[0067] Incidentally, it is preferable to provide a dust removal device for removing dust (such as seaweed, jellyfish, small fish, waste, etc.) in seawater at the water intake for taking in seawater used in the floating nuclear power generation system 1. Therefore, in the floating nuclear power generation system 1, at the water intakes 4DSL and 4DSR of the circulating water pipe 4D and at the water intake of the reactor auxiliary cooling seawater system for supplying cooling heat to auxiliaries around the reactor 3, a dust removal device is provided. FIG. 5 is a diagram showing an example of the dust removal device provided in the floating nuclear power generation system 1.

[0068] As shown in FIG. 5, the dust removal device 29 is provided with a dust removal pit 29A, an inlet 29C, a cyclone 29D, a sedimentation tank 29E, a discharge door 29G, and an outlet 29H.

[0069] The dust removal pit 29A is a space provided at the bottom or side of the floating body 2 and is a part that is always filled with seawater around the floating body 2. A cyclone 29D is provided at the center of the dust removal pit 29A. The cyclone 29D is located at the open end of the outlet 29H connected to a seawater system pump such as the circulating water pump 4E. The cyclone 29D has a conical internal shape and has an inlet 29C that opens along the tangential direction at the outermost diameter part. For this reason, when the seawater system pump operates with the dust removal pit 29A filled with seawater and seawater is sucked into the outlet 29H, a spiral water flow is generated in the cyclone 29D by the seawater flowing in from the inlet 29C. When the spiral water flow is generated, the dust D having a specific gravity greater than that of seawater is centrifugally separated in the cyclone 29D and settles into the sedimentation tank 29E provided below the cyclone 29D. An openable and closable discharge door 29G is provided at the lower part of the sedimentation tank 29E. For this reason, by appropriately opening the discharge door 29G, the dust D accumulated in the sedimentation tank 29E can be discharged from the sedimentation tank 29E. When the water intake is provided at the bottom of the floating body 2, depending on the displacement of the floating body 2, since the water intake is located at a depth of about 80 to 100 m, for example, the possibility of sucking in dust that is abundant near the sea surface is low. By combining the above-described effect of preventing the intrusion of a large number of migratory fish by the mine defense net, it is possible to suppress the dust that intrudes into the water intake as much as possible.

[0070] In addition, the dust collector 29 is provided with a strainer 29F for preventing relatively large dust D from flowing into the dust pit 29A. Further, the dust collector 29 is provided with a strainer 29B for preventing relatively large dust D from flowing into the inlet 29C. Therefore, for dust D that is not suitable for centrifugal separation, it can be removed by the strainer 29F or the strainer 29B.

[0071] Note that the floating nuclear power generation system 1 is not limited to one equipped with such a dust collector 29. The floating nuclear power generation system 1 may use, for example, a dust collector (traveling screen) that rotates an endless screen or other types of dust collectors.

[0072] <Matters related to core cooling> Next, the core cooling facility provided in the floating nuclear power generation system 1 will be described. During normal operation, the nuclear reactor 3 is cooled by the cold heat of the condenser 4C. However, during normal shutdown or emergency shutdown, the nuclear reactor 3 is cooled by various cooling facilities other than the condenser 4C. The cooling facilities used in the event of an emergency at the nuclear reactor 3 are called emergency core cooling systems (ECCS) and are composed of various cooling facilities such as a high-pressure injection water system, an isolation cooling system, and a low-pressure injection water system. Here, particularly characteristic matters in the various cooling facilities provided in the floating nuclear power generation system 1 will be described.

[0073] As described above, the floating nuclear power generation system 1 is equipped with an emergency condenser and a static containment cooling system. Since the floating nuclear power generation system 1 has a floating form floating on the sea, the decay heat of the reactor 3 can be removed stably for a long time by using the surrounding seawater, thereby greatly improving the safety. For this reason, in the floating nuclear power generation system 1, seawater can be introduced into the IC / PCCS pool 10. When seawater is introduced into the IC / PCCS pool 10, cooling can be continued by the natural circulation force due to the density difference of the seawater. For this reason, in the floating nuclear power generation system 1, the IC / PCCS pool 10 is provided as follows.

[0074] FIG. 6 is a view showing the IC / PCCS pool 10 from the lateral direction. FIG. 7 is a view showing the IC / PCCS pool 10 from the upward direction. In FIG. 6, the positional relationship in the height direction between the IC / PCCS pool 10, the pressure vessel 3E, and the sea surface is shown.

[0075] As can be seen from FIGS. 6 and 7, an emergency condenser 30A and a PCCS heat exchanger 30D are arranged in the IC / PCCS pool 10 (in FIG. 6, the illustration of the PCCS heat exchanger 30D is omitted for the convenience of the space on the paper surface). The IC / PCCS pool 10 in which the emergency condenser 30A and the PCCS heat exchanger 30D are arranged is higher than the reactor core C. The IC / PCCS pool 10 is provided with a communication valve 10A for communicating with the side ballast tank 28, communication valves 10B and 10C for communicating with the periphery (sea) of the floating body 2, and an atmosphere release pipe 10D for communicating with the atmosphere. Further, the emergency condenser 30A is connected to the inside of the pressure vessel 3E via a pipe 30B connected to the vicinity of the upper part of the pressure vessel 3E and a pipe 30C connected to the vicinity of the lower part of the pressure vessel 3E.

[0076] The inside of the IC / PCCS pool 10 is normally filled with fresh water. And even when the floating nuclear power generation system 1 experiences a complete loss of AC power, by opening the pipes 30B and 30C, the reactor 3 can be cooled by the emergency condenser 30A. Also, a path for connecting to the condensate storage tank 14 is provided in the IC / PCCS pool 10. Therefore, even when the floating nuclear power generation system 1 experiences a complete loss of AC power and the fresh water in the IC / PCCS pool 10 decreases, it is possible to continue cooling the reactor 3 with the fresh water stored in the condensate storage tank 14. However, if the fresh water in the IC / PCCS pool 10 or the condensate storage tank 14 decreases due to boiling and the complete loss of AC power continues, it may not be possible to continue cooling the reactor 3 with fresh water. Even in such a case, the floating nuclear power generation system 1 can fill the inside of the IC / PCCS pool 10 with ballast water by opening the communication valve 10A. Also, the floating nuclear power generation system 1 can fill the inside of the IC / PCCS pool 10 with seawater around the floating body 2 by opening the communication valve 10B and the communication valve 10C. If the inside of the IC / PCCS pool 10 is filled with either fresh water or seawater, it is possible to continue cooling the reactor core C using the emergency condenser 30A. Note that the floating nuclear power generation system 1 has a valve at an appropriate location for allowing seawater to flow from the surroundings of the floating body 2 into the side ballast tank 28, and the seawater in the side ballast tank 28 can be replenished in a timely manner even if it decreases.

[0077] Note that the floating nuclear power generation system 1 according to this embodiment is not limited to a form in which the emergency condenser 30A is responsible for condensing the steam in the pressure vessel 3E and the heat exchanger 30D for PCCS is responsible for condensing the steam in the containment vessel 3A. The emergency condenser 30A used for cooling the reactor core C when the primary system boundary is intact and the heat exchanger 30D for PCCS used for cooling the containment vessel 3A when the primary system boundary is damaged may complement or exchange their functions with each other by switching the system configuration by opening and closing valves. That is, by opening and closing the valves, the emergency condenser 30A may be connected to the upper part (upper drywell 3M) and the lower part (suppression pool 3H) in the containment vessel 3A. Also, by opening and closing the valves, the heat exchanger 30D for PCCS may be connected to the upper and lower parts in the pressure vessel 3E. The valve for performing such a system configuration switch may be an electric valve using a DC power source or a manual valve.

[0078] In the floating nuclear power generation system 1, a height difference is provided between the communication valve 10B and the communication valve 10C. Therefore, although convection occurs in the seawater in the IC / PCCS pool 10 heated by the emergency condenser 30A due to the density difference of the seawater caused by the temperature difference, an effect can be expected that the seawater in the IC / PCCS pool 10 naturally exchanges with the seawater around the floating body 2 due to the height difference between the communication valve 10B and the communication valve 10C.

[0079] In addition, if salt precipitates on the surfaces of the emergency condenser 30A or the heat exchanger 30D for PCCS, the heat exchange capacity may be reduced. Therefore, when seawater is introduced into the IC / PCCS pool 10, it is preferable to prevent the precipitation of salt due to the evaporation of seawater. The precipitation of salt can be suppressed by preventing the boiling (generation of voids) of seawater on the heat exchange surfaces of the emergency condenser 30A or the heat exchanger 30D for PCCS. Therefore, in order to suppress the temperature rise of the seawater in the IC / PCCS pool 10, it is advisable to use large-diameter valves for the communication valves 10A, 10B, and 10C. For example, if large-diameter valves are used for the communication valves 10B and 10C, the seawater in the IC / PCCS pool 10 can easily be exchanged with the seawater around the floating body 2, so that the temperature rise of the seawater in the IC / PCCS pool 10 can be suppressed as much as possible. Also, when seawater is used for cooling the emergency condenser 30A or the heat exchanger 30D for PCCS, such salt precipitation may occur. Therefore, in the initial stage when the decay heat immediately after the emergency shutdown of the reactor 3 is relatively large, an attempt is made to cool with fresh water, and it is preferable to start cooling with seawater when the fresh water has decreased due to evaporation or the like and the decay heat of the reactor 3 has also become small.

[0080] As described above, the floating nuclear power generation system 1 is provided with various facilities for facilitating cooling with seawater by taking advantage of the floating characteristics, as compared with nuclear power plants installed on land. Therefore, it can be said that the floating nuclear power generation system 1 can stably remove the decay heat of the reactor 3 by using the surrounding seawater for a long period of time. The seawater utilization function by opening the communication valves 10A, 10B, and 10C may be used not only for the IC / PCCS pool 10 but also for, for example, the fuel pool 8.

[0081] Note that the design concept of introducing seawater into the IC / PCCS pool 10 can also be applied to pressurized water reactors. For example, when the floating nuclear power generation system 1 is a pressurized water reactor, seawater is introduced into the secondary side of the steam generator that exchanges heat between the primary cooling system in which the reactor is provided and the secondary cooling system in which the turbine is provided, instead of the condensate of the secondary cooling system. Thereby, even when the condensate of the secondary cooling system is lost, it becomes possible to cool the coolant of the primary cooling system with the seawater introduced into the secondary side of the steam generator.

[0082] <Matters related to accident countermeasures> Next, the accident countermeasure equipment provided in the floating nuclear power generation system 1 will be described. As described above, the floating nuclear power generation system 1 is equipped with sufficient equipment for cooling the reactor 3, but various countermeasures assuming a serious accident are implemented as follows.

[0083] <Core catcher> Fig. 8 is a diagram showing the state in which the molten core drops from the bottom of the pressure vessel 3E. When the core melts in the reactor 3, the bottom of the pressure vessel 3E is damaged, and as shown in Fig. 8, the molten core may drop below the pressure vessel 3E. When the molten core drops below the pressure vessel 3E, the structural material of the floating body 2 below the pressure vessel 3E is heated. However, as described above, the floating body 2 has a double hull structure, and a bottom ballast tank 26 is provided at the bottom of the floating body 2. And, a large number of heat transfer plates 26B standing in the bottom ballast tank 26 are joined to the lower surface of the steel plate 26A of the floating body 2 that forms the bottom surface of the lower drywell 3N. For this reason, the steel plate 26A has a form that is strongly reinforced by the heat transfer plates 26B. In addition, in Fig. 8, it is shown that the inside of the bottom ballast tank 26 is partitioned by the heat transfer plates 26B, but water passages for allowing the ballast water to flow are provided at various positions of the heat transfer plates 26B. For this reason, the ballast water can freely flow in the bottom ballast tank 26 without being obstructed by the heat transfer plates 26B.

[0084] The bottom surface of the lower drywell 3N formed by the steel plate 26A and the heat transfer plates 26B functions as a core catcher. And, the steel plate 26A and the heat transfer plates 26B are in contact with the ballast water in the bottom ballast tank 26. Therefore, the bottom of the lower drywell 3N functions as a heat sink for releasing heat to the ballast water in the bottom ballast tank 26. For this reason, when the molten core drops from the pressure vessel 3E due to core melting, the molten core dropped from the pressure vessel 3E is heat-transferred to the ballast water in the bottom ballast tank 26 through the steel plate 26A and the heat transfer plates 26B.

[0085] If the molten core that falls from the bottom of the pressure vessel 3E comes into direct contact with a large amount of water, there is a concern that a steam explosion or a large amount of hydrogen may be generated. Therefore, when attempting to inject water into the molten core, it is necessary to take measures such as restricting the appropriate amount of water. However, it is not easy to control the amount of water injection during the progression of such a severe accident as core melting.

[0086] In this regard, in the floating nuclear power generation system 1 of the present embodiment, the steel plates 26A and the heat transfer plates 26B that form the bottom surface of the lower drywell 3N function not only as a core catcher but also as a heat sink for dissipating heat to the ballast water in the ship bottom ballast tank 26. For this reason, the molten core that has fallen to the bottom surface of the lower drywell 3N is stably cooled and solidified, and accumulates as fuel debris. And in this cooling method, since the molten core and a large amount of water do not come into direct contact, the possibility of generating a steam explosion or a large amount of hydrogen is low.

[0087] Also, in the floating nuclear power generation system 1 of the present embodiment, by making the pedestal that supports the pressure vessel 3E made of steel, the heat of the molten core in the pressure vessel 3E is also transferred to the suppression pool 3H via the pedestal. Thus, in the floating nuclear power generation system 1 of the present embodiment, even when core melting occurs, static countermeasures for the molten core that utilize the water in the ship bottom ballast tank 26 or the water in the suppression pool 3H are implemented. In addition, in order to suppress the influence of the pedestal coming into contact with the fuel debris as much as possible, a cylindrical partition wall may be installed inside the pedestal so that the heat of the fuel debris is transferred to the suppression pool 3H by a heat transfer pipe or the like. If such a partition wall and heat transfer means are provided, the integrity of the pedestal can be maintained even if core melting occurs by any chance.

[0088] <Water flooding function of the containment vessel 3A> FIG. 9 is an explanatory diagram regarding the flooding function of the containment vessel 3A. The floating nuclear power generation system 1 is designed such that the nuclear reactor 3 is positioned lower than the sea surface. For this reason, the floating nuclear power generation system 1 is equipped with a function to fill the inside of the containment vessel 3A with seawater. That is, the floating nuclear power generation system 1 is equipped with a seawater inlet pipe 3AP that connects the inside of the containment vessel 3A and the surroundings (sea) of the floating body 2. A seawater inlet valve 3AV is provided in the middle of the seawater inlet pipe 3AP.

[0089] In the normal state, the seawater inlet valve 3AV is closed, and as shown in FIG. 9(A), seawater does not flow into the containment vessel 3A. Here, if all means for injecting water into the pressure vessel 3E are lost due to some accident, the seawater inlet valve 3AV is opened. When the seawater inlet valve 3AV is opened, the seawater around the floating body 2 flows into the containment vessel 3A. As described above, the nuclear reactor 3 is located lower than the sea surface. Therefore, by opening the seawater inlet valve 3AV, as shown in FIG. 9(B), almost all of the containment vessel 3A is filled with seawater, and it becomes possible to indirectly cool the reactor core C in the pressure vessel 3E from the outside of the pressure vessel 3E. When filling the inside of the containment vessel 3A with seawater, in order to allow the air in the containment vessel 3A to escape, the floating nuclear power generation system 1 is provided with the seawater inlet pipe 3AP in two upper and lower stages. Thereby, in the initial state when seawater starts to flow into the containment vessel 3A, the upper-stage seawater inlet pipe 3AP serves as an air vent path, and the air in the containment vessel 3A is discharged. And when the inside of the containment vessel 3A is filled with seawater, the state where the containment vessel 3A is flooded is achieved. Note that a vent valve other than the seawater inlet valve 3AV may be provided for venting the air in the containment vessel 3A. A filter vent device for removing radioactive substances contained in the air may be provided in the middle of the air vent path.

[0090] <Submerging function of the floating nuclear power generation system 1> FIG. 10 is an explanatory diagram regarding the sinking function of the floating nuclear power generation system 1. The floating nuclear power generation system 1 is equipped with a function to sink the floating body 2. The sinking of the floating body 2 can be realized, for example, by opening a valve that communicates the inside and outside of the floating body 2, destroying the bottom of the ship, or filling the inside of the floating body 2 with seawater by various other methods.

[0091] Since the floating nuclear power generation system 1 adopts a form that floats on the sea, if all means for injecting water into the pressure vessel 3E are lost due to some accident, for example, as shown in FIG. 10(A), the floating nuclear power generation system 1 may be sunk. If the floating nuclear power generation system 1 sinks, the reactor 3 can be cooled with seawater. When it is desired to lift the floating nuclear power generation system 1 from the seabed, after several years have passed since the floating nuclear power generation system 1 was sunk and the decay heat of the reactor 3 has become sufficiently small, as shown in FIG. 10(B), a floating body F for lifting is prepared to lift the floating nuclear power generation system 1. The floating body F for lifting is a hollow body with a sealed structure, and it is possible to let seawater flow into the floating body F for lifting or drain the seawater inside the floating body F for lifting.

[0092] After preparing such a floating body F for lifting, as shown in FIG. 10(C), seawater is made to flow into the floating body F for lifting above the floating nuclear power generation system 1 that has sunk to the seabed, and the floating body F for lifting is sunk to the seabed. Then, the floating body F for lifting is connected to the floating nuclear power generation system 1. Next, the seawater inside the floating body F for lifting is drained. When the seawater inside the floating body F for lifting is drained, due to the buoyancy of the floating body F for lifting, the floating body F for lifting rises to the sea surface together with the floating nuclear power generation system 1. As a result, it becomes possible to attempt various disposals such as disassembling the floating nuclear power generation system 1 and removing nuclear fuel.

[0093] In the floating nuclear power generation system 1, even when it falls into a situation where the means of injecting water into the reactor 3 is lost, by using the above various functions that take advantage of the floating characteristics, the reactor 3 can be cooled with seawater, and a mechanism is provided that can sufficiently prevent radioactive substances from being released from the reactor 3. Therefore, compared with nuclear power plants installed on land, it is possible to use nuclear energy more safely.

Explanation of Reference Signs

[0094] R··Reactor system: T··Turbine system: F··Floating body for floating: C··Reactor core: D··Waste: 1··Floating nuclear power generation system: 2··Floating body: 3··Reactor: 4··Turbine generator: 5··Reactor equipment area: 6··Pit: 7··Reactor equipment area: 8··Fuel pool: 9··Desalination device: 10··IC / PCCS pool: 12··Various equipment areas: 13··Residential area: 14··Condensate storage tank: 18··Radar down area: 19··Ancillary equipment area: 20··Main transformer: 21··Auxiliary boiler: 22··Anchor chain: 23··Light oil tank: 24··Waste treatment room: 25··Bow ballast tank: 26··Bottom ballast tank: 27··Stern ballast tank: 28··Side ballast tank: 29··Dust removal device: 30··Emergency condensate system: 3A··Containment vessel: 3B··Nuclear fuel: 3C··Control rod: 3D··Recirculation pump: 3E··Pressure vessel: 3F··Relief safety valve: 3G··Exhaust pipe: 3H··Suppression pool: 3J··Main steam isolation valve: 3K··Main steam isolation valve: 3L··Main steam pipe: 3M··Upper drywell: 3N··Lower drywell: 4A··Turbine: 4B··Generator: 4C··Condenser: 4D··Circulating water pipe: 4E··Circulating water pump: 4F··Feed water pump: 4G··Feed water pipe: 3AP··Seawater inlet pipe: 3AV··Seawater inlet valve: 4DS··Water intake: 4DH··Water discharge port: 10A··Communication valve: 10B··Communication valve: 10C··Communication valve: 10D··Atmospheric vent pipe: 26A··Steel plate: 26B··Heat transfer plate: 29A··Dust removal pit 29B ·· Strainer: 29C ·· Inlet: 29D ·· Cyclone: 29E ·· Settling tank: 29F ·· Strainer: 29G ·· Discharge door: 29H ·· Outlet: 30A ·· Emergency condenser: 30B ·· Pipe: 30C ·· Pipe: 30D ·· Heat exchanger for PCCS

Claims

1. a nuclear reactor, a turbogenerator driven by steam from the nuclear reactor generated by the heat of the nuclear reactor, a floating body on which the nuclear reactor and the turbogenerator are arranged and which is moored at sea, a condenser that condenses the steam generated in the pressure vessel or the containment vessel where the nuclear reactor is located in an emergency by the heat of the stored water and returns it as condensate to the pressure vessel or the containment vessel, a water storage section in which the condenser is arranged and which stores the stored water, the water storage section has at least a bottom set lower than the draft line of the floating body, and a communication valve for directly or indirectly allowing water around the floating body to flow in is provided, a floating nuclear power generation system.

2. the floating body has at least a side ballast tank formed in a side portion of the floating body by a double hull structure, the water storage section has, as the communication valve, a first communication valve that communicates the inside of the water storage section with the side ballast tank, the floating nuclear power generation system according to claim 1.

3. the water storage section has, as the communication valve, a second communication valve that allows water around the floating body to flow into the water storage section, the floating nuclear power generation system according to claim 1.

4. the condenser is installed at a position at least higher than the nuclear reactor in the floating body, the floating nuclear power generation system according to any one of claims 1 to 3.

Images