Floating-type nuclear power generation system

Abstract

To provide a floating-type nuclear power generation system which is stable to a tide.SOLUTION: The floating-type nuclear power generation system includes a reactor, a turbine generator driven by steam generated by heat of the reactor, and a floating body in which the reactor and the turbine generator are arranged, the floating body being streamlined when viewed from above and having a bow side at one end in a longitudinal direction alone moored.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Nuclear power generation systems have been proposed not only in the form of systems installed on land, but also in the form of floating systems that float on the sea (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 151898 / 1983 [Patent Document 2] Japanese Patent Application Publication No. 151899 / 1983 [Patent Document 3] Japanese Patent Application Publication No. 52-149589 [Non-patent literature]

[0004] [Non-Patent Document 1] Buongiorno, J. et al. “The Offshore Floating Nuclear Plant Concept.” Nuclear Technology 194.1 (2016) [Non-patent document 2] Seismic response characteristics of floating structures for floating nuclear power plants (part 2) - Vertical seismic isolation characteristics of a floating structure with an air chamber at the bottom - Central Research Institute of Electric Power Industry, Yutaka Hagiwara et al., August 1, 1987 Summary of the Invention [Problem to be solved by the invention]

[0005] Nuclear power generation systems can be placed on the ocean in three different locations: coastal locations within a few kilometers of land, offshore locations several tens of kilometers from land, or in the open ocean several hundred kilometers from land. When a nuclear power generation system is placed on the coast, it is located very close to land, making it easy to transmit power and transport materials. However, because the seabed is shallower in coastal areas than offshore, the wave height of tsunamis that arrive in the event of an earthquake is higher than in offshore locations. Furthermore, if a nuclear power generation system is located offshore close to land, residents on land may be forced to evacuate in the event of a serious accident at the nuclear power generation system. On the other hand, installing a nuclear power generation system in the open ocean several hundred kilometers from land would require the laying of long-distance undersea cables for power transmission, making it difficult to transport materials, making this unrealistic. Therefore, taking all of these factors into consideration, it is preferable to install a floating nuclear power generation system offshore, somewhat away from land.

[0006] However, compared to coastal areas, offshore currents tend to be stronger and move in different directions, so when deploying a floating nuclear power generation system offshore, it is essential to ensure the stability of the floating structure against the currents.

[0007] Therefore, the present application discloses a floating nuclear power generation system that is stable against tidal currents. [Means for solving the problem]

[0008] In order to solve the above problem, in the present invention, the floating body on which the reactor and turbine generator are arranged is made streamlined when viewed from above, and only the bow side of one end in the longitudinal direction is moored.

[0009] In detail, the present invention relates to a floating nuclear power plant comprising a nuclear reactor, a turbine generator driven by steam generated by the heat of the nuclear reactor, and a float on which the nuclear reactor and the turbine generator are arranged, the float having a streamlined shape when viewed from above, and only one end, the bow side, of the float is moored in the longitudinal direction. It is an electricity system.

[0010] In the floating nuclear power generation system described above, the float on which the reactor and turbine generator are mounted is streamlined, and only one longitudinal end of the float is moored, so when the float is subjected to a tidal current, the moored bow naturally faces upstream as it floats on the sea. As a result, the resistance that the float receives from the tidal current is reduced by the streamlined shape of the float, ensuring stability against the tidal current.

[0011] The float may be moored by an anchor chain attached to the bow side, and a submarine cable for connecting the floating nuclear power generation system to the onshore power grid may be suspended from the vicinity of the bow of the float to the seabed. If the submarine cable for connecting the floating nuclear power generation system to the onshore power grid is suspended from the vicinity of the bow of the float to the seabed, the submarine cable will not be affected even if the direction of the bow of the float, which is moored by the anchor chain attached to the bow side, changes due to tidal currents.

[0012] Furthermore, the turbine generator may be located closer to the bow of the float than the reactor in the longitudinal direction of the float. If a submarine cable for connecting the floating nuclear power generation system to an onshore power grid is suspended from near the bow of the float to the seabed, it is more reasonable to locate the turbine generator that generates electricity closer to the submarine cable than to the reactor.

[0013] The floating nuclear power generation system may further include a main transformer arranged on the bow side of the float relative to the turbine generator in the longitudinal direction of the float. The main transformer, which boosts the electricity generated by the turbine generator to the voltage of the power grid, is provided between the turbine generator and the submarine cable in terms of the circuit, so it is reasonable to arrange the main transformer on the bow side of the float relative to the turbine generator in the longitudinal direction of the float.

[0014] The turbine generator may also be positioned so that the rotation axis of the turbine and generator is along the longitudinal direction of the floater, thereby eliminating the possibility of the turbine blades flying towards the reactor in the event of a turbine missile. [Effects of the Invention]

[0015] The floating nuclear power generation system described above is stable against tidal currents. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing the arrangement of equipment in a floating nuclear power generation system according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the system configuration of a floating nuclear power generation system according to an embodiment. [Figure 3] Figure 3 shows how a floating body changes direction. [Figure 4] FIG. 4 is a diagram illustrating the situation when a tsunami hits a floating nuclear power generation system. [Figure 5] FIG. 5 is a diagram showing an example of a dust removal device provided in the floating nuclear power generation system 1. As shown in FIG. [Figure 6] Figure 6 shows the IC / PCCS pool from the side. [Figure 7] Figure 7 shows the IC / PCCS pool from above. [Figure 8] FIG. 8 shows the molten core falling from the bottom of the pressure vessel. [Figure 9] FIG. 9 is an explanatory diagram regarding the flooding function of the containment vessel. [Figure 10] FIG. 10 is an explanatory diagram of the sinking function of the floating nuclear power generation system. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following describes an embodiment of the present invention. The embodiment described below is one aspect of the present invention and does not limit the technical scope of the present invention.

[0018] <Outline of equipment layout> Fig. 1 is a schematic diagram showing the arrangement of equipment in a floating nuclear power generation system 1 according to an embodiment. Fig. 1(A) shows the layout of various equipment provided in the floating nuclear power generation system 1 as viewed from above. Fig. 1(B) shows the layout of various equipment provided in the floating nuclear power generation system 1 as viewed from the side.

[0019] The floating nuclear power generation system 1 is a floating power generation system that can be floated on the sea. For this purpose, the floating nuclear power generation system 1 includes a float 2. As can be seen from FIG. 1(A), the float 2 is a streamlined float. However, the float 2 is not a vessel intended for autonomous navigation on the sea. The float 2 floats on the sea while being moored in order to transmit the electricity generated by the floating nuclear power generation system 1 to land. To reduce resistance to tidal currents, the float 2 is moored at only one end in the longitudinal direction and floats on the sea with the other end unmoored. For this reason, the float 2 floats on the sea like a windsock. In other words, when the float 2 is subjected to tidal currents, it floats on the sea with the moored part naturally facing upstream of the tidal current.

[0020] Since the float 2 has such a streamlined shape, in this embodiment, for convenience, the moored portion of the float 2 in the longitudinal direction will be referred to as the "bow side," and the unmoored portion will be referred to as the "stern side." Therefore, in Fig. 1, the left side of the page is the "bow side," and the right side of the page is the "stern side." Also, Fig. 1(B) shows the internal configuration of the floating nuclear power generation system 1 as seen from the port side of the float 2.

[0021] In this embodiment, a streamlined float 2 is exemplified, but the float 2 may be a non-streamlined float. The float 2 used in the floating nuclear power generation system 1 may be, for example, a cylindrical float that is circular when viewed from above, a rectangular parallelepiped float that is square when viewed from above, or any other float of various shapes.

[0022] As shown in FIG. 1, the floating nuclear power generation system 1 includes a reactor 3 located near the center of a float 2, and a turbine generator 4 located closer to the bow than the reactor 3. The reactor 3 generates steam by boiling water with heat generated by nuclear fission. The turbine generator 4 generates electricity by rotating a generator with a steam-driven turbine. In this embodiment, a floating nuclear power generation system 1 using a boiling water reactor (BWR) that drives the turbine generator 4 with steam from the reactor 3 is exemplified, but the floating nuclear power generation system 1 may be any other type of floating nuclear power generation system. The power system 1 is, for example, a pressurized water reactor (PWR). Alternatively, various other methods may be used.

[0023] The floating nuclear power generation system 1 is equipped with various types of equipment in addition to the float 2, reactor 3, and turbine generator 4 described above. The floating nuclear power generation system 1 is equipped, for example, with reactor equipment areas 5 and 7, a pit 6, and a fuel pool 8 around the reactor 3. The floating nuclear power generation system 1 is also equipped with a desalination plant 9, an IC / PCCS pool 10, various equipment areas 12, an accommodation area 13, and a waste treatment room 24, which are arranged aft of the reactor 3. The floating nuclear power generation system 1 is also equipped with a condensate storage tank 14 arranged between the reactor 3 and the turbine generator 4. The floating nuclear power generation system 1 is also equipped with a laydown area 18 and an ancillary equipment area 19, which are arranged near the bow of the float 2. A main transformer 20 and an auxiliary boiler 21 are installed in the ancillary equipment area 19. The floating nuclear power generation system 1 is also equipped with a light oil tank 23 on the deck near the bow of the float 2. The floating nuclear power generation system 1 also includes a bow ballast tank 25 and a bottom ballast tank 26 for controlling the attitude of the floating body 2. 26, stern ballast tank 27, and side ballast tank 28.

[0024] The reactor equipment areas 5 and 7 are equipped with various types of reactor equipment that are installed outside the containment vessel of the reactor 3. The equipment that is installed in the reactor equipment areas 5 and 7 includes, for example, pumps and valves of various reactor cooling equipment such as an emergency core cooling system and a residual heat removal system, pumps and valves of a pool water cooling system that cools the fuel pool, compressed air equipment for control, ventilation and air conditioning equipment, an emergency diesel generator that serves as an emergency power source, DC power supply equipment using storage batteries, and various other equipment.

[0025] Pit 6 is a pit for temporarily storing various items during periodic inspections and refueling. Examples of items to be stored in pit 6 include a steam separator and a steam dryer that are placed above the nuclear fuel inside reactor 3.

[0026] The fuel pool 8 is a pool for storing unused or spent nuclear fuel. The nuclear fuel for the reactor 3 is in the form of fuel assemblies. For this reason, the fuel pool 8 is provided with racks for storing the fuel assemblies at appropriate intervals. In addition, a fuel exchange machine for transferring the fuel assemblies between the reactor 3 and the fuel pool 8 is provided above the fuel pool 8.

[0027] The desalination device 9 is a device that desalinates seawater. Because the floating nuclear power generation system 1 is used while floating on the sea, it is not possible to obtain freshwater that is almost free of salt from rivers, as is the case with facilities on land. For this reason, the floating nuclear power generation system 1 is equipped with a desalination device 9 that removes salt from seawater to desalinate it, in order to secure reactor cooling water and various other types of water. Various methods, such as reverse osmosis and evaporation, can be used as the desalination method for the desalination device 9.

[0028] The IC / PCCS pool 10 is equipped with an IC heat exchanger and a PCCS heat exchanger. The IC heat exchanger is an isolation condenser (IC) and is used for all AC power supplies. It cools the reactor 3 in the event of a loss of power or other problem that causes the containment vessel to be isolated. The PCCS heat exchanger is part of the Passive Containment Cooling System (PCCS) and cools the steam that is released into the containment vessel in the event of a severe accident.

[0029] The various equipment area 12 is provided with a central control room for operating the floating nuclear power generation system 1, an entrance / exit control room for controlling entry and exit to the radiation controlled area, and various other equipment. The emergency diesel generator and DC power supply equipment described above may be provided in the various equipment area 12 instead of the reactor equipment areas 5 and 7.

[0030] The living area 13 is provided with living facilities for the operators and others staying on the floating nuclear power generation system 1. Examples of living facilities include private rooms with berths, a dining room with cooking equipment, bathing facilities, recreational facilities, and various other facilities.

[0031] Various facilities for treating radioactive waste are installed in the waste treatment room 24. Examples of radioactive waste to be treated in the waste treatment room 24 include liquid waste such as wastewater generated in radiation controlled areas and miscellaneous solid waste such as waste materials generated in various operations. These wastes are reduced in volume in the waste treatment room 24 by evaporation and concentration, compression, incineration, etc., and stored within the float 2 before being transported from the float 2.

[0032] The condensate storage tank 14 is a tank that stores 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 to supply water to the condenser during normal operation and to inject water into the reactor 3 in an emergency. .

[0033] The laydown area 18 is a work space for disassembling and inspecting various large pieces of equipment such as the turbine generator 4. The laydown area 18 is on the same floor as the operating floor for the turbine generator 4, and large pieces of equipment can be easily transported using crane equipment installed above the operating floor.

[0034] Various types of auxiliary equipment, such as a main transformer 20 and an auxiliary boiler 21, are located in the auxiliary equipment area 19. The main transformer 20 is a transformer that boosts the voltage of 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 using heat generated by burning diesel oil.

[0035] The floating nuclear power generation system 1 is moored on the sea by an anchor chain 22 attached to the bow side of the float 2. As mentioned above, when the floating nuclear power generation system 1 is subjected to a tidal current, it floats on the sea with the moored part naturally facing upstream of the tidal current. For this reason, the submarine cable for connecting the floating nuclear power generation system 1 to the onshore power grid is suspended from near the bow of the float 2 toward the seabed, similar to the anchor chain 22. For this reason, it is reasonable to place the main transformer 20 for stepping up the electricity generated by the turbine generator 4 to the voltage of the power grid near the bow of the float 2, close to the submarine cable, as shown in Figure 1.

[0036] Furthermore, the auxiliary boiler 21 is used to provide steam for the ground of the turbine generator 4 and to heat the steam equipment around the turbine when the floating nuclear power generation system 1 starts up. For this reason, it is reasonable to place the auxiliary boiler 21 near the turbine generator 4.

[0037] For this reason, the floating nuclear power generation system 1 adopts a configuration in which the main transformer 20 and the auxiliary boiler 21 are arranged in an auxiliary equipment area 19 provided on the bow side of the float 2. Also, the floating nuclear power generation system 1 adopts a configuration in which a light oil tank 23 for storing light oil to be supplied to the auxiliary boiler 21 is arranged above the auxiliary equipment area 19. In addition to the main transformer 20 and the auxiliary boiler 21, the auxiliary equipment area 19 also includes switching equipment such as a line switch (LS) for opening and closing the electrical connection between the submarine cable and the main transformer 20. may be installed.

[0038] 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 used to control 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 to cool the reactor 3 in an emergency in the floating nuclear power generation system 1. Water can be injected into the bow ballast tank 25, the bottom ballast tank 26, and the stern ballast tank 27 naturally using the water pressure of seawater, for example, by opening a water intake provided on the bottom of the floating body 2. A pump or the like may also be used for water injection, if necessary. Water can also be discharged from the bow ballast tank 25, the bottom ballast tank 26, and the stern ballast tank 27 using a pump or an ejector.

[0039] The outline of the equipment layout of the floating nuclear power generation system 1 according to this embodiment has been described above, but the above-described equipment layout is only an example, and other equipment layouts may be adopted. Next, an outline of the system configuration of the floating nuclear power generation system 1 will be described.

[0040] <System configuration overview> 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 is mainly composed of a reactor system R and a turbine system T. The reactor 3 mentioned above is the main component of the reactor system R. The turbine generator 4 mentioned above is the main component of the turbine system T.

[0041] The reactor system R containing 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. The turbine system T containing the turbine generator 4 is equipped with various facilities such as a condenser 4C, circulating water piping 4D, a circulating water pump 4E, and a feedwater pump 4F in addition to the turbine 4A and generator 4B that constitute the turbine generator 4.

[0042] The containment vessel 3A is a vessel that contains a pressure vessel 3E that contains nuclear fuel 3B and the like, and serves to contain radioactive materials that are released from the pressure vessel 3E in the event of a meltdown accident in the reactor 3, etc. The containment vessel 3A may be made of concrete, or may be made of the same steel that constitutes the floater 2. The containment vessel 3A contains the pressure vessel 3E that contains the reactor 3 in its center, and has an upper dry well 3M formed above the pressure vessel 3E and a lower dry well 3N formed below the pressure vessel 3E. The containment vessel 3A also has a suppression pool 3H around the lower dry well 3N.

[0043] The pressure vessel 3E is a container that contains nuclear fuel 3B and the like, and serves to contain water and steam for cooling the reactor 3. Several hundred nuclear fuel 3B are arranged in the center of the pressure vessel 3E in the form of fuel assemblies, forming the main body of the reactor 3. Control rods 3C that can move up and down by a drive mechanism provided at the bottom of the pressure vessel 3E are inserted into the gaps between the fuel assemblies in the main body of the reactor 3. When the control rods 3C are withdrawn from the reactor 3 and the reactor 3 goes into a critical state, the reactor 3 continues to generate heat. Furthermore, when the control rods 3C are inserted into the reactor 3 and the reactor 3 goes into a subcritical state, the heat generated by the reactor 3 gradually decreases.

[0044] A recirculation pump 3D is provided in the pressure vessel 3E. The recirculation pump 3D is responsible for removing heat from the reactor 3 and controlling the reactor power output by forcibly circulating water, which is the reactor coolant, in the liquid phase within the pressure vessel 3E. Note that the floating nuclear power generation system 1 of this embodiment is assumed to be an advanced boiling water reactor (ABWR), and therefore in FIG. 2 the recirculation pump 3D is 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, for example, have a recirculation system in which the recirculation pump and circulation piping are arranged outside the pressure vessel 3E.

[0045] A main steam pipe 3L is connected to the pressure vessel 3E to send steam generated in 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 containment vessel 3A, main steam isolation valves 3J and 3K are provided near the penetrations of the containment vessel 3A to enable isolation of the containment vessel 3A. A safety relief valve 3F is provided midway along 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 downstream of the safety relief valve 3F is located in a suppression pool 3H.

[0046] The turbine 4A and generator 4B that make up the turbine generator 4 are connected by the same rotating shaft. The turbine 4A has a structure in which an impeller is housed inside a casing. A condenser 4C is provided below the turbine 4A to condense the steam that has passed through the turbine 4A. Inside the condenser 4C, there are provided a number of thin tubes that form part of the path of the circulating water pipe 4D that connects the water intake and discharge outlets that are provided below the waterline on the exterior surface of the floating body 2, and the steam is condensed using the cold heat of seawater that is pumped by a circulating water pump 4E that is provided on the path of the circulating water pipe 4D. For this reason, the steam supplied from the reactor 3 through the main steam pipe 3L and The pressure difference with the inside of the condenser 4C applies power to the impeller to rotate the generator 4B, which then rotates the generator 4B and generates electricity. The condensed water in the condenser 4C is fed back into the pressure vessel 3E by the feedwater pump 4F via the feedwater piping 4G.

[0047] Note that Figure 2 only shows an outline of the reactor system R and turbine system T, and in reality, a wide variety of equipment is installed. For example, important equipment such as a steam control valve and a turbine bypass valve is installed near the turbine 4A of the main steam pipe 3L. The turbine bypass valve may be a 100% bypass valve that sends all of the main steam at rated output directly to the condenser 4C without passing through the turbine 4A, or it may have a lower bypass capacity. In addition, important equipment such as a feedwater flow control valve, a condensate demineralizer, and a feedwater heater is installed in the feedwater pipe 4G. In addition, piping for the emergency core cooling system is installed inside and outside the containment vessel 3A. The turbine 4A is a combination of a high-pressure turbine and multiple low-pressure turbines.

[0048] 2, each device is shown in a single system, but the devices in the floating nuclear power generation system 1 are multiplexed. For example, there are multiple circulating water pumps 4E and multiple feedwater pumps 4F.

[0049] In the reactor system R, the position of the control rod 3C is adjusted so that the reactor 3 maintains a predetermined reactor output. In the turbine system T, the opening of the steam control valve is adjusted so that the turbine generator 4 maintains a predetermined rotation speed, and the feedwater flow rate of the feedwater pump 4F is adjusted so that the reactor 3 maintains a predetermined water level. With this configuration, the floating nuclear power generation system 1 transmits thermal energy generated by the nuclear reaction in the reactor 3 as electrical energy to the power grid via the generator 4B, which is synchronized with the grid frequency.

[0050] The outline of the system configuration of the floating nuclear power generation system 1 according to this embodiment has been described above. Next, each characteristic part of the floating nuclear power generation system 1 will be described in detail.

[0051] <Matters concerning the shape of floating body 2> As described above, the floating nuclear power generation system 1 according to this embodiment uses a streamlined float 2. Since the floating nuclear power generation system 1 is used while moored at sea, the decay heat of the reactor 3 can be removed stably over a long period of time by using the surrounding seawater, thereby greatly improving safety.

[0052] An example of an offshore floating nuclear power plant is the Russian Academician Lomonosov, which began commercial operation in 2020. In the 1990s, Japan also considered installing a nuclear power plant on a floating flat barge. However, similar to land-based nuclear power plants, the reactors of nuclear power plants on ship-type and flat barges are located above sea level. Therefore, using seawater to cool the reactor in ship-type and flat barge-type nuclear power plants requires electricity, engines, and other power sources for pumping. Maintaining stable cooling over the long term poses a challenge, as it requires external replenishment of electricity and fuel.

[0053] To overcome this challenge, Professor Buongiorno and his colleagues at the Massachusetts Institute of Technology (hereinafter referred to as "MIT") have devised a design that incorporates a nuclear reactor system into a cylindrical floating structure used for offshore oil drilling. However, the cylindrical floating structure proposed by MIT places the nuclear reactor at the bottom and the steam turbine and generator at the top. 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 top. Furthermore, because the cylindrical floating structure is roughly circular when viewed from above, when it is manufactured in a general horizontal shipbuilding dock, dead space is created within the dock, which reduces manufacturing efficiency. Furthermore, it is difficult to build a structure that supports such heavy objects at the top because the reactor is located at the bottom. A structure in which a reactor is placed with a steam turbine and generator on top poses challenges, such as the draft being several times deeper than that of a large ship, making it difficult to manufacture.

[0054] Therefore, the floating nuclear power generation system 1 of this embodiment employs a streamlined float 2, and nuclear power generation equipment such as a nuclear reactor 3 and a turbine generator 4 is disposed inside the float 2, which has a double hull structure similar to that of a large tanker. In the floating nuclear power generation system 1 of this embodiment, the reactor 3 is disposed below the seawater surface, as shown in FIG. 1(B). This makes it possible to realize a passive heat exchange system with seawater that does not require power from electricity, engines, or the like, which is not possible with ships or flat-plate barges. The passive heat exchange system realized in the floating nuclear power generation system 1 of this embodiment will be described in detail later.

[0055] As mentioned above, the floating body 2 is moored on the sea by the anchor chain 22, and therefore floats like a windsock. Figure 3 shows how the floating body 2 changes direction. When the floating body 2 receives a tidal current, it floats on the sea with its bow, moored by the anchor chain 22, naturally facing upstream of the tidal current. As a result, the streamlined shape of the floating body reduces resistance, making it possible to minimize the tension applied to the anchor chain 22.

[0056] The floating nuclear power system 1 has several advantages due to the streamlined float 2, in addition to the aforementioned reduction in resistance to tidal currents when moored. For example, the streamlined shape of the float 2 allows for maximum utilization of the space within a typical horizontal shipbuilding dock when manufacturing the floating nuclear power system 1, thereby enabling efficient manufacturing of the floating nuclear power system 1. In other words, by using multiple cranes in the shipbuilding dock, it is possible to simultaneously perform manufacturing work near the reactor 3 and manufacturing work near the turbine generator 4. Furthermore, manufacturing the floating nuclear power system 1 at a centralized manufacturing base such as a shipbuilding dock is expected to improve manufacturing quality and reduce manufacturing costs. Because the floating nuclear power system 1 can be transported by sea, it can be easily exported to countries bordering the sea. Therefore, exporting floating nuclear power systems 1 manufactured at a centralized manufacturing base by sea offers advantages in both quality and cost compared to establishing manufacturing bases around the world.

[0057] Another advantage of the floating nuclear power system 1 due to the use of a streamlined float 2 is the ease of loading and unloading materials at sea. That is, with a streamlined float 2, the port and starboard sides are generally straight, making it easy for other ships to berth alongside the port or starboard side. If a ship can berth alongside the port or starboard side of the float 2, cargo can be transferred with the straight sides touching each other, facilitating the transfer of, for example, food for operators, diesel fuel consumed by the auxiliary boiler 21 and emergency diesel generator, chemicals used for water quality control, casks storing nuclear fuel, and various other maintenance parts.

[0058] Another advantage of the floating nuclear power generation system 1 due to the adoption of a streamlined float 2 is the layout advantage of various components 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, 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 undersea cable. In a floating nuclear power generation system 1 in which each component is interconnected in this manner, it is more rational to arrange the reactor 3, turbine generator 4, and main transformer 20 in order. In this regard, the streamlined float 2 makes it possible to arrange the reactor 3, turbine generator 4, and main transformer 20 in this order from stern to bow. Furthermore, the streamlined float 2 makes it possible to position the turbine generator 4 so that its rotation axis is aligned along the longitudinal direction of the float 2, as shown in Figure 2. This eliminates the possibility of the turbine blade flying toward the reactor 3, even in the unlikely event of a turbine missile occurring, in which a turbine blade breaks off during rotation. In addition, in the floating nuclear power generation system 1, To prevent missiles from being generated, the casing is strong enough that the turbine blades cannot penetrate it.

[0059] <Matters concerning the mooring of Floating Body 2> Next, we will describe the characteristic features of the floating nuclear power generation system 1 that are provided for mooring the streamlined float 2. Because the floating nuclear power generation system 1 employs a configuration in which the streamlined float 2 is moored, it is equipped with a device for controlling the attitude of the float 2 by itself. An example of a device for controlling the attitude of the float 2 is a thruster. If the float 2 is provided with an electrically operated screw thruster that can freely rotate the propulsion direction, it becomes possible to freely change the direction of the float 2 around the mooring part and to control the position of the float 2. Furthermore, if the float 2 is provided with a thruster, it becomes possible to continue to maintain the float 2 in a fixed position when the anchor chain 22 breaks.

[0060] Furthermore, a circulating water pump 4E, for example, can be used as a device for independently controlling the attitude of the float 2. The circulating water pump 4E is a pump that supplies seawater to the condenser 4C, which has one of the largest cooling capacities of any nuclear power generation facility. Therefore, the circulating water pump 4E has one of the largest capacities of any pump 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 piping 4D, the float 2 can be moved at sea. Therefore, in the floating nuclear power generation system 1 of this embodiment, as shown in Figure 3, the circulating water system is configured so that the circulating water pump 4EL, installed in the circulating water piping 4D connecting the port-side intake 4DSL and the starboard-side discharge outlet 4DHR, pumps seawater from the port side to the starboard side, and the circulating water pump 4ER, installed in the circulating water piping 4D connecting the starboard-side intake 4DSR and the port-side discharge outlet 4DHL, pumps seawater from the starboard side to the port side. During normal times when the direction (posture) of the float 2 is left to the tidal current, the flow rates of the circulating water pumps 4EL and 4ER are balanced so that the water is pumped symmetrically by the circulating water pump 4E. When it is desired to move the float 2 to the port side, the flow rate of the circulating water piping 4D is adjusted so that the flow rate of the circulating water pump 4EL is greater than the flow rate of the circulating water pump 4ER. Furthermore, when it is desired to move the float 2 to the starboard side, the flow rate of the circulating water piping 4D is adjusted so that the flow rate of the circulating water pump 4ER is greater than the flow rate of the circulating water pump 4EL. The flow rate of the circulating water piping 4D can be adjusted, for example, by adjusting the opening of a flow control valve provided on the turbine generator 4 or by stopping the circulating water pump 4ER. Controlling the direction of the float 2 by adjusting the flow rate in this manner is effective not only for changing direction around the mooring parts but also for correcting positional deviation of the float 2.

[0061] In addition to the circulating water pump 4E, other devices for controlling the attitude of the floating body 2 by itself include, for example, a reactor auxiliary cooling water pump for the reactor building cooling water system (RCW). Turbine building cooling seawater pump (RSW), Turbine auxiliary cooling system (TCW) The present embodiment is also applicable to turbine auxiliary cooling seawater pumps (TSW) for the Turbine Seawater System. In the floating nuclear power generation system 1, the reactor auxiliary cooling seawater pump and the turbine auxiliary cooling seawater pump can also be used for position control, similar to the circulating water pump 4E. The floating nuclear power generation system 1 of this embodiment has multiple reactor auxiliary cooling seawater pumps and multiple turbine auxiliary cooling seawater pumps, 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 float 2, it is possible to correct the positional deviation of the float 2.

[0062] The floating nuclear power generation system 1 of this embodiment is assumed to have three low-pressure turbines as the turbines 4A. Two circulating water pipes 4D are connected to each of the three condensers 4C arranged below each low-pressure turbine for multiplexing. For this reason, six circulating water pipes 4D and circulating water pumps 4E (4EL, 4ER) are shown in FIG. 3. 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 arranged symmetrically, and may be, for example, four or less, or eight or more. In addition, in FIG. 3, the water intake 4DSL and the water discharge 4DHL are arranged close to each other, but in order to prevent the short circuit phenomenon, they may be arranged apart from each other, or may be arranged so that the opening directions are staggered, such as to the side and below the floating body 2.

[0063] Another example of a device for changing the direction of the floating body 2 is a tugboat. By permanently tethering a tugboat to the floating body 2, not only can the direction of the floating body 2 be changed, but also, for example, in the event of an emergency in the sea area where the floating nuclear power generation system 1 is installed, it is possible to cut the anchor chain 22 and quickly move the floating nuclear power generation system 1. Examples of emergencies that may occur in specific sea areas include the occurrence of natural disasters such as the eruption of an undersea volcano, and armed attacks by terrorists or military forces. In response to armed attacks targeting the floating nuclear power generation system 1, it is desirable to take measures such as setting up an area within a predetermined distance from the floating nuclear power generation system 1 to restrict the entry of ships and other vessels and monitor maritime traffic, or setting up a torpedo defense net around the floating nuclear power generation system 1 to prevent the approach of torpedoes and suspicious ships.

[0064] If the direction of the float 2 can be changed, the following measures can be taken, for example. Figure 4 is a diagram illustrating the situation when a tsunami hits the floating nuclear power generation system 1. Figure 4(A) shows the floating nuclear power generation system 1 as seen from above, and Figure 4(B) shows the floating nuclear power generation system 1 as seen from the side.

[0065] For example, as shown in Figure 4(A), assume that the tidal current is flowing downward and to the right on the page of Figure 4. In this case, the floating nuclear power generation system 1 moored by the anchor chain 22 floats due to the tidal current in the state shown by symbol P1 in Figure 4(A), that is, with the bow of the floater 2 facing upward and to the left. In this state, assume that, for example, an earthquake or typhoon occurs centered on the left side of the page of Figure 4, causing a tsunami to flow to the right.

[0066] If the floating nuclear power system 1 receives this tsunami with the bow of the float 2 pointing upward and left, the floating nuclear power system 1 will receive the tsunami from the port side of the float 2. Therefore, the floating nuclear power system 1 may tilt to the starboard side due to the tsunami received from the port side of the float 2. On the other hand, if the generation of the tsunami is detected and the direction of the float 2 is immediately started to change, and the state shown by symbol P2 in Figure 4(A) is reached, that is, the state in which the bow of the float 2 is pointed to the left, the floating nuclear power system 1 will receive the tsunami from the bow side of the float 2. Therefore, the floating nuclear power system 1 can minimize the possibility of the float 2 tilting to either the port side or starboard side. In the floating nuclear power generation system 1, since the float 2 is long from bow to stern, even if a tsunami hits the bow side of the float 2, the floating nuclear power generation system 1 will hardly tilt in the fore-and-aft direction, as shown in Figure 4(B).

[0067] Although Figure 4 shows the floating nuclear power generation system 1 relatively close to land, it is preferable that the floating nuclear power generation system 1 be moored offshore at a distance of several tens of kilometers from land. As shown in Figure 4(B), tsunamis have the tendency to grow larger as they approach land in shallow waters. For this reason, if the floating nuclear power generation system 1 is moored offshore at a distance of several tens of kilometers from land in deep waters, it is possible to relatively reduce the size of the tsunami that the floating nuclear power generation system 1 receives, although this depends on the topography of the seabed.

[0068] The distance from land where the floating nuclear power generation system 1 is suitable for mooring is, for example, 30 km or more. If the floating nuclear power generation system 1 is moored at sea 30 km or more from land, there will be no residential area within the evacuation plan area required by Japanese law. In other words, if a large-scale accident were to occur in the floating nuclear power generation system 1, Even if a disaster occurs, it can be said that there is almost no chance that residents on land will need to evacuate.

[0069] Incidentally, it is preferable to provide a dust removal device that removes debris (seaweed, jellyfish, small fish, waste, etc.) from the seawater at the intake port that takes in the seawater used in the floating nuclear power generation system 1. Therefore, in the floating nuclear power generation system 1, dust removal devices are provided at the intake ports 4DSL, 4DSR of the circulating water piping 4D and at the intake port of the reactor auxiliary cooling seawater system that supplies cold heat to auxiliary machinery around the reactor 3. Fig. 5 is a diagram showing an example of a dust removal device provided in the floating nuclear power generation system 1.

[0070] As shown in FIG. 5, the dust removal device 29 includes a dust removal pit 29A, an inlet 29C, a cyclone 29D, a settling tank 29E, a discharge door 29G, and an outlet 29H.

[0071] The dust removal pit 29A is a space provided on the bottom or side of the float 2 and is constantly filled with seawater surrounding the float 2. A cyclone 29D is provided in the center of the dust removal pit 29A. The cyclone 29D is located at the open end of an outlet 29H connected to a seawater system pump, such as the circulating water pump 4E. The cyclone 29D has a conical interior shape and an inlet 29C that opens tangentially at its outermost diameter. Therefore, when the seawater system pump is activated while the dust removal pit 29A is filled with seawater and seawater is sucked into the outlet 29H, the seawater flowing in from the inlet 29C generates a spiral water flow within the cyclone 29D. This spiral water flow causes debris D, which has a greater specific gravity than seawater, to be centrifuged within the cyclone 29D and settle into a settling tank 29E located below the cyclone 29D. An openable discharge door 29G is provided at the bottom of the settling tank 29E. Therefore, by opening the discharge door 29G as needed, the debris D accumulated in the settling tank 29E can be discharged from the settling tank 29E. If the water intake is provided at the bottom of the float 2, the water intake will be located at a depth of, for example, approximately 80 to 100 meters, depending on the displacement of the float 2, making it less likely to suck in debris that is abundant near the sea surface. By combining this with the effect of preventing large amounts of migratory fish from entering using the torpedo protection net mentioned above, it is possible to minimize the amount of debris that enters the water intake.

[0072] The dust remover 29 is provided with a strainer 29F that prevents relatively large debris D from flowing into the dust removal pit 29A. The dust remover 29 is also provided with a strainer 29B that prevents relatively large debris D from flowing into the inlet 29C. Therefore, debris D that is not suitable for centrifugation can be removed by the strainer 29F or the strainer 29B.

[0073] It should be noted that the floating nuclear power generation system 1 is not limited to one equipped with such a dust removal device 29. The floating nuclear power generation system 1 may be one that uses, for example, a dust removal device that rotates an endless screen (traveling screen) or other types of dust removal device.

[0074] <Matters related to core cooling> Next, the core cooling equipment provided in the floating nuclear power generation system 1 will be described. During normal operation, the reactor 3 is cooled by the cold heat of the condenser 4C, but during normal shutdown or emergency shutdown, the reactor 3 is cooled by various cooling equipment other than the condenser 4C. The cooling equipment used in an emergency for the reactor 3 is called the Emergency Core Cooling System (ECCS), and is composed of various cooling equipment such as a high-pressure water injection system, an isolation cooling system, and a low-pressure water injection system. Here, particularly characteristic features of the various cooling equipment provided in the floating nuclear power generation system 1 will be described.

[0075] As described above, the floating nuclear power system 1 is equipped with an emergency condenser and a passive containment vessel cooling system. Because the floating nuclear power system 1 is a floating structure that floats on the sea, it can significantly improve safety by stably removing decay heat from the reactor 3 over a long period of time using surrounding seawater. For this reason, the floating nuclear power system 1 is capable of inflowing seawater into the IC / PCCS pool 10. When seawater is allowed to flow into the IC / PCCS pool 10, cooling can be continued by the natural circulation force caused by the density difference of the seawater. For this reason, the floating nuclear power system 1 has the IC / PCCS pool 10 arranged as follows:

[0076] Fig. 6 is a side view of the IC / PCCS pool 10. Fig. 7 is a top view of the IC / PCCS pool 10. Fig. 6 shows the positional relationship between the IC / PCCS pool 10 and the pressure vessel 3E in the height direction above sea level.

[0077] 6 and 7, an isolation condenser 30A and a PCCS heat exchanger 30D are disposed in the IC / PCCS pool 10 (the PCCS heat exchanger 30D is not shown in FIG. 6 due to space limitations). The IC / PCCS pool 10, in which the isolation condenser 30A and the PCCS heat exchanger 30D are disposed, 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. The isolation 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.

[0078] The IC / PCCS pool 10 is normally filled with fresh water. Even if the floating nuclear power generation system 1 experiences a loss of all AC power supplies, the reactor 3 can be cooled by the emergency condenser 30A by opening the pipes 30B and 30C. The IC / PCCS pool 10 also has a path for connecting to the condensate storage tank 14. Therefore, even if the floating nuclear power generation system 1 experiences a loss of all AC power supplies and the fresh water in the IC / PCCS pool 10 decreases, the reactor 3 can continue to be cooled by the fresh water stored in the condensate storage tank 14. However, if the loss of all AC power supplies continues even after the fresh water in the IC / PCCS pool 10 and the condensate storage tank 14 decreases due to boiling, it may become impossible to continue cooling the reactor 3 with fresh water. Even in such a case, the floating nuclear power generation system 1 can fill the IC / PCCS pool 10 with ballast water by opening the communication valve 10A. Furthermore, the floating nuclear power generation system 1 can fill the IC / PCCS pool 10 with seawater around the float 2 by opening the communication valves 10B and 10C. If 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 isolation condenser 30A. The floating nuclear power generation system 1 has valves at appropriate locations for allowing seawater to flow from around the float 2 into the side ballast tanks 28, so that seawater in the side ballast tanks 28 can be replenished as needed even if it decreases.

[0079] The floating nuclear power generation system 1 according to this embodiment is not limited to the configuration in which the isolation condenser 30A condenses steam in the pressure vessel 3E and the PCCS heat exchanger 30D condenses steam in the containment vessel 3A. The isolation condenser 30A, which is used to cool the reactor core C when the primary system boundary is intact, and the PCCS heat exchanger 30D, which is used to cool the containment vessel 3A when the primary system boundary is damaged, may complement or exchange each other's functions by switching the system configuration by opening and closing a valve. That is, the isolation condenser 30A may be connected to the upper part (upper dry well 3M) and lower part (suppression pool 3H) in the containment vessel 3A by opening and closing a valve. Also, the PCCS heat exchanger 30D may be connected to the upper part and lower part in the pressure vessel 3E by opening and closing a valve. The valve for switching the system configuration in this way may be an electric power source using a DC power source. It may be a valve operated or a manual valve.

[0080] Furthermore, in the floating nuclear power generation system 1, there is a difference in elevation between the communicating valves 10B and 10C. As a result, convection occurs in the seawater in the IC / PCCS pool 10 heated by the isolation condenser 30A due to a difference in seawater density caused by a temperature difference, but the difference in elevation between the communicating valves 10B and 10C is expected to have the effect of naturally replacing the seawater in the IC / PCCS pool 10 with the seawater around the floating body 2.

[0081] Note that salt deposition on the surfaces of the isolation condenser 30A and the PCCS heat exchanger 30D may reduce heat exchange capacity. Therefore, when seawater is introduced into the IC / PCCS pool 10, it is preferable to prevent salt deposition due to evaporation of the seawater. Salt deposition can be suppressed by preventing boiling of seawater (the generation of voids) on the heat exchange surfaces of the isolation condenser 30A and the PCCS heat exchanger 30D. Therefore, in order to suppress the temperature rise of the seawater in the IC / PCCS pool 10, it is preferable to use large-diameter valves for the communicating valves 10A, 10B, and 10C. For example, using large-diameter valves for the communicating valves 10B and 10C makes it easier for the seawater in the IC / PCCS pool 10 to be replaced with seawater around the floating body 2, thereby suppressing the temperature rise of the seawater in the IC / PCCS pool 10 as much as possible. Furthermore, when seawater is used to cool the emergency condenser 30A or the PCCS heat exchanger 30D, such salt precipitation may occur. Therefore, it is preferable to attempt cooling with fresh water in the initial stage immediately after an emergency shutdown of the reactor 3 when the decay heat is relatively high, and then start cooling with seawater when the amount of fresh water has decreased due to evaporation, etc., and the decay heat of the reactor 3 has also decreased.

[0082] As described above, the floating nuclear power generation system 1 is provided with various facilities that make it easier to cool it with seawater, taking advantage of the floating structure compared to land-based nuclear power plants. Therefore, it can be said that the floating nuclear power generation system 1 can stably remove decay heat from the reactor 3 for a long period of time by using the surrounding seawater. The function of using seawater by opening the communication valves 10A, 10B, 10C can be used not only in the IC / PCCS pool 10 but also in the fuel pool 8, for example.

[0083] The design concept of introducing seawater into the IC / PCCS pool 10 can also be applied to pressurized water reactors. For example, if the floating nuclear power generation system 1 is a pressurized water reactor, seawater is introduced into the secondary side of the steam generator, which exchanges heat between the primary cooling system in which the reactor is installed and the secondary cooling system in which the turbine is installed, instead of the condensate of the secondary cooling system. This makes it possible to cool the coolant of the primary cooling system with the seawater introduced into the secondary side of the steam generator, even if the condensate of the secondary cooling system is lost.

[0084] <Matters related to accident prevention measures> Next, we will explain the accident countermeasure equipment provided in the floating nuclear power generation system 1. As mentioned above, the floating nuclear power generation system 1 is equipped with sufficient equipment to cool the reactor 3, but various countermeasures are also taken in anticipation of a serious accident, as described below.

[0085] <Core Catcher> FIG. 8 is a diagram showing the state in which the molten core falls from the bottom of the pressure vessel 3E. When the core melts in the reactor 3, the bottom of the pressure vessel 3E may be damaged, and the molten core may fall below the pressure vessel 3E as shown in FIG. 8. When the molten core falls below the pressure vessel 3E, the structural material of the float 2 below the pressure vessel 3E is heated. However, as mentioned above, the float 2 has a double hull structure, and a bottom ballast tank 26 is provided at the bottom of the float 2. A large number of heat transfer plates 26B are attached to the underside of the steel plate 26A of the float 2, which forms the bottom surface of the lower dry well 3N. Therefore, the steel plate 26A is strongly reinforced by the heat transfer plates 26B. Note that in FIG. 8, Although the inside of the bottom ballast tank 26 is shown as being partitioned by heat transfer plates 26B, water passages for circulating ballast water are provided at various locations on the heat transfer plates 26B. Therefore, the ballast water can freely flow inside the bottom ballast tank 26 without being obstructed by the heat transfer plates 26B.

[0086] The bottom surface of the lower dry well 3N, which is formed by the steel plate 26A and the heat transfer plate 26B, functions as a core catcher. The steel plate 26A and the heat transfer plate 26B are in contact with the ballast water in the bottom ballast tank 26. Therefore, the bottom of the lower dry well 3N functions as a heat sink for dissipating heat to the ballast water in the bottom ballast tank 26. Therefore, if the molten core falls from the pressure vessel 3E due to a core meltdown, the heat of the molten core that has fallen from the pressure vessel 3E is transferred to the ballast water in the bottom ballast tank 26 via the steel plate 26A and the heat transfer plate 26B.

[0087] If the molten core falling from the bottom of Pressure Vessel 3E were to come into direct contact with a large amount of water, there is a concern that a steam explosion or a large amount of hydrogen would be generated. For this reason, if an attempt is made to inject water into the molten core, measures must be taken to limit the amount of water injected. However, it is not easy to control the amount of water injected in this way while a severe accident such as a core meltdown is progressing.

[0088] In this regard, in the floating nuclear power generation system 1 of this embodiment, the steel plates 26A and heat transfer plates 26B that form the bottom surface of the lower dry well 3N function not only as a core catcher but also as a heat sink for dissipating heat to the ballast water in the bottom ballast tank 26. Therefore, the molten core that falls to the bottom surface of the lower dry well 3N is stably cooled and solidified, and then deposited as fuel debris. Furthermore, in this cooling method, the molten core does not come into direct contact with a large amount of water, so there is a low possibility of a steam explosion or the generation of a large amount of hydrogen.

[0089] Furthermore, in the floating nuclear power generation system 1 of this embodiment, the pedestal supporting the pressure vessel 3E is made of steel, so that the heat of the molten core in the pressure vessel 3E is also transferred to the suppression pool 3H via the pedestal. As such, in the floating nuclear power generation system 1 of this embodiment, even in the event of a core meltdown, passive countermeasures against the molten core are implemented, utilizing the water in the bottom ballast tanks 26 and the water in the suppression pool 3H. Note that, in order to minimize the impact of the pedestal coming into contact with fuel debris, a cylindrical bulkhead may be installed inside the pedestal, and the heat of the fuel debris may be transferred to the suppression pool 3H via a heat transfer tube or the like. If such a bulkhead and heat transfer means are provided, the integrity of the pedestal can be maintained even in the unlikely event of a core meltdown.

[0090] <Flooding function of Containment Vessel 3A> 9 is an explanatory diagram of the flooding function of the containment vessel 3A. The floating nuclear power generation system 1 is designed so that the reactor 3 is located below sea level. For this reason, the floating nuclear power generation system 1 is equipped with a function to fill 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 with the surroundings (sea) of the float 2. A seawater inlet valve 3AV is provided midway along the seawater inlet pipe 3AP.

[0091] Under normal conditions, the seawater inlet valve 3AV is closed, and as shown in Figure 9(A), seawater does not flow into the containment vessel 3A. If all means for injecting water into the pressure vessel 3E are lost due to some kind of accident, the seawater inlet valve 3AV is opened. When the seawater inlet valve 3AV is opened, seawater around the floating body 2 flows into the containment vessel 3A. As mentioned above, the reactor 3 is located below sea level. Therefore, by opening the seawater inlet valve 3AV, as shown in Figure 9 As shown in (B), most of the containment vessel 3A is filled with seawater, making it possible to indirectly cool the reactor core C inside the pressure vessel 3E from outside the pressure vessel 3E. To allow air to escape from the containment vessel 3A when the containment vessel 3A is filled with seawater, the floating nuclear power generation system 1 is provided with two seawater inlet pipes 3AP, one above the other. As a result, in the initial state when seawater begins to flow into the containment vessel 3A, the upper seawater inlet pipe 3AP serves as an air vent path, allowing the air inside the containment vessel 3A to be discharged. Once the containment vessel 3A is filled with seawater, the containment vessel 3A becomes flooded. A vent valve other than the seawater inlet valve 3AV may be provided to vent air from the containment vessel 3A. A filter vent device may be provided along the air vent path to remove radioactive materials from the air.

[0092] <Sinking function of floating nuclear power generation system 1> 10 is an explanatory diagram of the sinking function of the floating nuclear power generation system 1. The floating nuclear power generation system 1 has a function of sinking the float 2. The float 2 can be sinking by, for example, opening a valve that connects the inside and outside of the float 2, destroying the bottom of the vessel, or filling the inside of the float 2 with seawater by various other methods.

[0093] Because the floating nuclear power generation system 1 is designed to float on the sea, if all means for injecting water into the pressure vessel 3E are lost due to some kind of accident, the floating nuclear power generation system 1 may be sunk, for example, as shown in FIG. 10(A). If the floating nuclear power generation system 1 is sunk, the reactor 3 can be cooled with seawater. If it is desired to raise the floating nuclear power generation system 1 from the seabed, a floating float F is prepared to raise the floating nuclear power generation system 1, as shown in FIG. 10(B), once 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. The floating float F is a hollow body with an airtight structure, and it is possible to inject seawater into the floating float F and drain the seawater from the inside of the floating float F.

[0094] After preparing such a floating float F, as shown in FIG. 10(C), seawater is poured into the floating float F above the floating nuclear power generation system 1 that is submerged on the seabed, and the floating float F is submerged on the seabed. Then, the floating float F is connected to the floating nuclear power generation system 1. Next, the seawater inside the floating float F is discharged. Once the seawater inside the floating float F is discharged, the buoyancy of the floating float F causes the floating float F to rise to the sea surface together with the floating nuclear power generation system 1. This makes it possible to attempt various disposal methods, such as dismantling the floating nuclear power generation system 1 and removing the nuclear fuel.

[0095] In this way, even if the floating nuclear power generation system 1 were to encounter a situation where it were unable to inject water into the reactor 3, it would be possible to use the above-mentioned various functions that take advantage of the floating design to cool the reactor 3 with seawater and sufficiently prevent radioactive materials from being released from the reactor 3. Therefore, it is possible to use nuclear energy more safely than in land-based nuclear power plants. [Explanation of symbols]

[0096] R··Reactor system: T··Turbine system: F··Floating float: C··Reactor core: D··Refuse: 1··Floating nuclear power system: 2··Float: 3··Reactor: 4··Turbine generator: 5··Reactor equipment area: 6··Pit: 7··Reactor equipment area: 8··Fuel pool: 9··Desalination plant: 10··IC / PCCS pool: 12··Various equipment areas: 13··Accommodation area: 14··Condensate storage tank: 18·· Laydown area: 19 · Auxiliary equipment area: 20 · Main transformer: 21 · Auxiliary boiler: 22 · Anchor chain: 23 · Diesel oil tank: 24 · Waste treatment room: 25 · Bow ballast tank: 26 · Bottom ballast tank: 27 · Aft ballast tank: 28 · Side ballast tank: 29 · Dust removal system: 30 · Emergency condenser system: 3A · Containment vessel: 3B · Nuclear fuel: 3C · Control rods: 3D ··Recirculation pump: 3E··Pressure vessel: 3F··Safety relief valve: 3G··Exhaust pipe: 3H··Suppression pool: 3J··Main steam isolation valve: 3K··Main steam isolation valve: 3L··Main steam pipe: 3M··Upper dry well: 3N··Lower dry well: 4A··Turbine: 4B··Generator: 4C··Condenser: 4D··Circulating water piping: 4E··Circulating water pump: 4F··Feedwater pump: 4G··Feedwater piping: 3AP··Seawater inlet pipe: 3AV··Seawater inlet valve: 4DS ··Water intake: 4DH··Water discharge: 10A··Communicating valve: 10B··Communicating valve: 10C··Communicating valve: 10D··Atmospheric release 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··Immunity condenser: 30B··Piping: 30C··Piping: 30D··Heat exchanger for PCCS

Claims

1. A nuclear reactor and 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 disposed, The floating body has a streamlined shape when viewed from above, and only the bow side of one end in the longitudinal direction is moored. Floating nuclear power generation system.

2. The floating body is moored by an anchor chain provided on the bow side, a submarine cable for connecting the floating nuclear power generation system to an onshore power grid is suspended from the vicinity of the bow of the float to the seabed; 2. The floating nuclear power generation system according to claim 1.

3. the turbine generator is disposed closer to the bow of the float than the reactor in the longitudinal direction of the float, 3. The floating nuclear power generation system according to claim 2.

4. a main transformer disposed on the bow side of the float relative to the turbine generator in the longitudinal direction of the float, 4. The floating nuclear power generation system according to claim 3.

5. The turbine generator is arranged so that the rotation axes of the turbine and the generator are aligned along the longitudinal direction of the floating body.

5. The floating nuclear power generation system according to claim 1.

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