JP2013036921A - Nuclear power plant support vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an AC power source and cooling functions of a nuclear reactor and a spent fuel pool, or spent fuel pit, in the event of an earthquake and tsunami.SOLUTION: A nuclear power station support vessel 1 is equipped with a backup system for nuclear power plants located in coastal areas. The backup system includes: an AC current generator; an AC current distributor for supplying the AC current generated by the AC current generator to AC power loads, installed as part of a nuclear power plant system, that are used for cooling at least any one of a reactor and a spent fuel pool or a spent fuel pit therein; and a cooling water distribution system for supplying cooling water to cooling facilities, installed as part of the nuclear power plant system, capable of cooling at least any one of the reactor and the spent fuel pool or the spent fuel pit.

Description

  The present invention relates to a nuclear power plant support ship, and more particularly to a ship for supporting a safety function of a nuclear power plant in the event of an earthquake or tsunami.

  At nuclear power plants, safety design is conducted for design basis events defined in the examination guidelines. On the other hand, research and examination on severe accidents, which are events that greatly exceed the design standard events, have been conducted. The severe accident states that “an event that greatly exceeds the design basis event and is not in the state where appropriate core cooling or reactivity control can be performed by means assumed in the evaluation of the safety design. It is defined as “an event leading to damage” (Non-patent Document 1). As severe accident scenarios, for example, all AC power source loss, reactor scram failure, decay heat removal function loss, water injection failure to the core are assumed (in the case of boiling water nuclear power plant) (Non-patent Document 1) ). In recent years, it has been pointed out that there is a need to maintain the safety functions of nuclear power plants against earthquakes and tsunamis resulting therefrom.

“Accident management as a countermeasure against severe accidents in light water reactor facilities for power generation”, May 28, 1992, Nuclear Safety Commission

  To deal with severe accidents, it is necessary to take measures focusing on the individual scenarios of severe accidents, but in many scenarios it is important to secure AC power sources and to use nuclear reactors and spent fuel pools or spent fuel. Cooling of a pit (hereinafter, a spent fuel pit may be simply referred to as a pit). Therefore, it is important to further improve the tolerance of these functions when a severe accident occurs.

  It is an object of the present invention to provide a means for supporting a nuclear power plant that can be an option for securing an AC power source against an earthquake and a tsunami and ensuring a cooling function of a nuclear reactor and a spent fuel pool or a spent fuel pit. Objective.

  The nuclear power plant support vessel according to the present invention is equipped with a backup system for a nuclear power plant installed on the shore coastal area. The backup system is an AC power generation facility and an AC power source load that is installed as part of a nuclear power plant system and can be used to cool the reactor and / or spent fuel pool or spent fuel pit In addition, an AC current supply facility for supplying an AC current generated by the AC current generation facility, and at least one of a nuclear reactor, a spent fuel pool, or a spent fuel pit installed as part of a nuclear power plant system. A cooling water supply facility for supplying cooling water to a cooling facility capable of cooling is included.

  One option when there is a need to support a nuclear power plant located on the coastal land is to place an emergency facility on the power plant site and use that facility in an emergency. is there. In this method, it is easy to avoid or reduce the influence of the tsunami by appropriately selecting the installation location (for example, installation on a hill). On the other hand, the direct influence (earthquake acceleration) due to the earthquake may not differ greatly depending on the installation location. On the other hand, the acceleration of the earthquake is virtually zero at sea, and the height of the tsunami (sea level difference) is sufficiently small offshore to some extent. In other words, ships can easily avoid the effects of earthquakes and tsunamis, and are suitable as a backup system for nuclear power plants installed on the coastal land.

  According to the present invention, there is provided a support means for a nuclear power plant that can be an option for securing an AC power source against an earthquake and a tsunami and ensuring a cooling function of a nuclear reactor and a spent fuel pool or a spent fuel pit. be able to.

It is the schematic of the equipment mounted in the nuclear power plant support ship which concerns on this invention.

  Hereinafter, embodiments of a nuclear power plant support vessel according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of equipment mounted on a nuclear power plant support vessel 1. The nuclear power plant support vessel 1 is equipped with a backup system for a nuclear power plant installed on the coastal area on the shore. The onshore coastal area usually means a location along the coast, but a location on the coastal coast that faces the lake, river, etc., where the nuclear power plant support vessel 1 can berth is included. When the target nuclear power plant has a dedicated port facility in the power plant premises, it is preferable that the nuclear power plant support vessel 1 is of a size that can berth the existing port facility. Since the port facilities dedicated to nuclear power plants are normally assumed to be berthed by a cask transfer ship (3000 ton class) that transfers spent fuel, a ship of the same level is preferable as the nuclear power plant support ship 1.

  Backup systems can be broadly classified into AC power supply facilities and cooling water supply facilities. A nuclear power plant usually includes a DC power supply facility using a battery and an AC power supply facility using a diesel generator 61 as power sources that can be used in an emergency. The DC power supply is limited to power supply to facilities with a small load such as instrumentation and control due to the limitation of battery capacity, and the usable time is as short as several hours. For this reason, it is necessary to drive equipment with large power consumption, such as a pump, by AC power supply, and it is important to supply AC power stably over a long period of time. For the above reasons, the nuclear power plant support vessel 1 is equipped with AC power supply equipment.

  The AC power supply facility includes an AC current generation facility and an AC current supply facility. The alternating current generation facility is typically a diesel generator (D / G) 11 that uses a diesel engine as a prime mover, and in some cases, another prime mover such as a gas turbine can be combined with the generator. The nuclear power plant support vessel 1 may be used also as a diesel engine or a gas turbine provided for navigation, or may be installed separately for exclusive use. The alternating current generation facility further includes a fuel storage facility 12 (such as a light oil tank) in which fuel to be supplied to the diesel generator 11 is stored. The diesel generator 11 and the fuel storage facility 12 may be fixedly installed on the nuclear power plant support vessel 1 or transported to the power plant premises or in the building after berthing of the nuclear power plant support vessel 1 as a portable type. And may be installed.

  AC power supply equipment is installed as part of the nuclear power plant system and used to cool the reactor and / or spent fuel pool (boiling water type) or spent fuel storage pit (pressurized water type) It is provided to supply an alternating current generated by an alternating current generation facility to an alternating current power supply load. Examples of AC power load include high pressure core water injection pump, residual heat removal pump, spent fuel pool cooling pump (boiling water type), high pressure injection pump, preheating removal pump, spent fuel pit cooling pump (pressurized water type), etc. Can be mentioned. In addition, power can be supplied to the containment container spray pump (pressurized water type).

  The AC current supply facility includes a switchboard 13 for supplying AC current generated by the diesel generator 11 to an AC power load such as a pump in a nuclear power plant. The switchboard 13 is used for supplying power to a high-voltage switchboard 62 (for example, a 6.6 kV or 6.9 kV metal clad gear) that is originally installed in the power plant. For connection between the high voltage switchboard 62 and the switchboard 13, a terminal box 63 originally installed in the power plant or mounted on the nuclear power plant support vessel 1 may be used. The switchboard 13 may be fixedly installed on the nuclear power plant support vessel 1 or may be transported and installed in the power plant site or in the building after berthing of the nuclear power plant support vessel 1 as a portable type. The diesel generator 11 and the fuel storage facility 12 may be fixed, and the switchboard 13 may be portable.

  The nuclear power plant support vessel 1 is equipped with a cable 14 for connecting the switchboard 13 and the high voltage switchboard 62 as an AC current supply facility. When the switchboard 13 is portable, the diesel generator 11 and the switchboard 13 are connected to each other. A cable for tying is also installed.

  The backup system may include a direct current generation facility and a direct current supply facility (both not shown). The direct current generating facility is a battery, and it is preferable that the direct current generating facility be configured to be charged as necessary by power supply from the diesel generator 11. A DC current supply facility is a DC current generation facility installed in a DC power source load installed as part of a nuclear power plant system that can be used to cool the reactor and / or spent fuel pool or pit. Used to supply the generated direct current. Examples of DC power supply loads include instrument power supplies, nuclear reactor control devices, emergency diesel generator control panels, and the like.

  The direct current supply equipment basically includes the same equipment as the alternating current supply equipment. Specifically, the DC current supply facility includes a switchboard used for feeding (connecting) a DC switchboard originally installed in the power plant, and a cable connecting the switchboards.

  The cooling water supply facility is provided to supply cooling water to a cooling facility installed as part of the nuclear power plant system and capable of cooling the reactor and / or the spent fuel pool or pit. Yes. Cooling equipment is used to inject water into the reactor and spent fuel pool or pit (maintenance of submerged fuel), and exhaust heat from the reactor and spent fuel pool or pit to seawater (heat removal from decay heat). It is a facility having at least one of the functions, and is synonymous with a system or a system that executes the function. Regardless of whether the cooling facility belongs to a safety system or a regular system by design, it may be anything as long as the above functions are expected in accident management. Examples of cooling facilities include: high pressure core water injection system, residual heat removal system, reactor auxiliary cooling water system, seawater system, spent fuel pool cooling system (boiling water type), high pressure injection system, preheating removal system, reactor auxiliary Machine cooling water system, seawater system, spent fuel pit cooling system (pressurized water type) and the like.

  In particular, the reactor auxiliary cooling water system and the sea water system circulate non-radioactive fresh water and sea water, respectively, the design pressure of the system is low, and it is easy to connect pipes such as pipes and hoses from the outside. It is suitable for supporting the cooling function from the outside of the power plant because the point, main equipment and piping are installed outside the radiation control area. For this reason, the cooling water supply equipment of the nuclear power plant support ship 1 according to the present embodiment is equipped with a reactor auxiliary equipment cooling water system and a seawater system support equipment.

  Specifically, the nuclear power plant support vessel 1 is equipped with a temporary cooling water pump 21 as an alternative facility for the nuclear reactor auxiliary coolant pump 73. The temporary cooling water pump 21 may be fixedly installed in the nuclear power plant support ship 1 or may be portable. The nuclear power plant support vessel 1 is further equipped with a fresh water conduit 22 such as a hose or a pipe. The fresh water pipe 22 is connected to the reactor auxiliary machine cooling water system 71 via a connection portion 72 provided in advance, and the switching valve 74 is closed and the switching valve 24 is opened, whereby the reactor auxiliary machine cooling water system 71 is connected. At the same time, the fresh water circulation line 23 can be configured. The temporary cooling water pump 21 described above is installed on the fresh water pipeline 22.

  Further, the nuclear power plant support vessel 1 is equipped with a seawater conduit 25 having a seawater intake portion 26 and a water discharge portion 27, and a temporary seawater pump 28 located in the intake portion 26 of the seawater conduit 25. Yes. The temporary seawater pump 28 is a vertical pump, and is provided as an alternative facility for a reactor auxiliary machine cooling seawater pump (not shown). The temporary seawater pump 28 is preferably provided with pump protection means 29 such as a strainer or a fence. This is because in the case of a tsunami, many solid substances may be suspended in the seawater due to the outflow of onshore installations or the raising of dust on the seabed. A temporary heat exchanger 30 is provided on the fresh water conduit 22 and the sea water conduit 25. The temporary heat exchanger 30 is provided as an alternative facility for the reactor auxiliary equipment cooling system heat exchanger 75. The temporary cooling water pump 21 circulates fresh water in the fresh water circulation line 23, and the temporary heat exchanger 30 exhausts the heat of the fresh water in the fresh water circulation line 23 to the seawater conduit 25. The exhaust heat to the seawater conduit 25 is exhausted to the sea by the temporary seawater pump 28.

  Thus, since the nuclear power plant support vessel 1 is equipped with the functions of the reactor auxiliary cooling water system and the reactor auxiliary cooling seawater system, these functions, in particular, the reactor auxiliary cooling water pump 73 and the same. Quick backup is possible when the function of the seawater pump is lost.

  The cooling water supply facility may include a portable water storage facility 31 (temporary water tank). By connecting water pipes 32 such as hoses and pipes mounted on the nuclear power plant support vessel 1 to the cooling facility originally installed in the power plant, a water supply line to the cooling facility can be configured. An example of the cooling facility is the above-described reactor auxiliary coolant water system, which can be supplemented when the amount of water circulating through the system decreases due to, for example, a pipe breakage. Alternatively, it can be directly connected to a reactor or spent fuel pool or pit, or a condensate tank (pressurized water type) to connect to the reactor or spent fuel pool or pit, or condensate tank (pressurized water type). It may be used as a water source for water injection. The water storage facility 31 preferably stores fresh water, but can also store seawater.

  A portable transfer pump 33 that can supply water stored in the water storage facility 31 to the cooling facility is installed on the water pipe 32. The transfer pump 33 desirably has a performance equivalent to that of the fire extinguishing pump, and has a head corresponding to the system pressure of the transfer destination and the pressure loss to the transfer destination.

  The nuclear power plant support vessel 1 itself may be provided with a fixed water storage facility 34 (a large capacity temporary water tank). Fresh water is stored in the fixed water storage facility 34 in advance, and water can be sent to the portable water storage facility 31 by the transfer pump 35. Since the fixed water storage facility 34 and the portable water storage facility 31 may be installed apart from each other, the transfer pump 35 is higher than the transfer pump 33 (for example, equivalent to a fire pump installed in a fire ship) It is desirable that By providing the fixed water storage facility 34, a large amount of fresh water can be supplied quickly. In this case, by providing the nuclear power plant support vessel 1 with the seawater desalination facility 36, it is also possible to stably supply fresh water. On the other hand, when a continuous supply of a large amount of cooling water is required, the seawater is pumped from a water intake facility having the same function as the pump protection means 29, and the reactor is not transferred by the transfer pump 35 via the water storage facility 31. Alternatively, seawater can be directly connected to a system capable of pouring water into a spent fuel pool or pit, or a condensate tank (pressurized water type).

  The nuclear power plant support vessel 1 preferably includes a compressed air supply facility for supplying compressed air. The compressed air supply equipment is used for supplying compressed air to an instrumented compressed air system that plays an important function particularly in monitoring the state of at least one of a nuclear reactor and a spent fuel pool or a pit. The compressed air supply facility includes a compressor 41, and supplies compressed air to a compressed air tank 65 previously installed in the nuclear power plant through a junction box 66 previously installed in the nuclear power plant. .

  In addition to this, the nuclear power plant support vessel 1 can be provided with various facilities as necessary. For example, by providing the heliport 51, even if the nuclear power plant support vessel 1 cannot berth at the port, it is possible to transport portable equipment and necessary personnel to the power plant site using a helicopter. In addition, a wireless device for receiving information such as a tsunami warning, a decontamination facility, and boric acid water for suppressing the reactivity of the core can be provided.

  The nuclear power plant support vessel 1 described above has a very limited impact on the ship itself even when earthquakes and tsunamis occur simultaneously or sequentially and have a significant impact on the safety of the nuclear power plant. Therefore, it is effective as a backup for nuclear power plants. The operation method of the nuclear power plant support vessel 1 is not particularly limited. For example, when the ship is normally anchored at sea or in the harbor near the power plant, there is a possibility that a large tsunami will attack. Evacuate offshore to avoid the effects of tsunami. After that, when the risk of tsunami decreases, you can berth at the port and start necessary support activities.

DESCRIPTION OF SYMBOLS 1 Nuclear power station support ship 11 Diesel generator 12 Fuel storage equipment 13 Power distribution board 21 Temporary cooling water pump 28 Temporary seawater pump 30 Temporary heat exchanger 31,34 Water storage equipment 33,35 Transfer pump 41 Compressor 51 Heliport

Claims (8)

A nuclear power plant support vessel equipped with a backup system for a nuclear power plant installed on the shore coast,
The backup system is
AC current generation equipment,
Occurred at the AC current generating facility in an AC power source load installed as part of a nuclear power plant system that can be used to cool the reactor and / or spent fuel pool or spent fuel pit AC current supply equipment for supplying AC current;
A cooling water supply facility for supplying cooling water to a cooling facility installed as part of a nuclear power plant system and capable of cooling at least one of a nuclear reactor and a spent fuel pool or a spent fuel pit;
Including a nuclear power plant support vessel. The backup system is
DC current generating equipment,
Generated by the DC current generating facility in a DC power source load installed as part of a nuclear power plant system and used for cooling the reactor and / or spent fuel pool or spent fuel pit DC current supply equipment for supplying DC current;
The nuclear power plant support vessel according to claim 1, comprising:   The backup system is installed as a part of a nuclear power plant system and compressed air is supplied to a measurement facility that can be used for monitoring the state of at least one of a nuclear reactor and a spent fuel pool or a spent fuel pit. The nuclear power plant support vessel according to claim 1 or 2, comprising a compressed air supply facility for supply.   The AC current generation facility includes a diesel generator, a fuel storage facility in which fuel to be supplied to the diesel generator is stored, and a switchboard for supplying AC current generated by the diesel generator to the AC power load. The nuclear power plant support vessel according to any one of claims 1 to 3, further comprising: The cooling water supply equipment is
A fresh water pipeline capable of constituting a fresh water circulation line together with the cooling facility by being connected to the cooling facility;
A cooling water pump installed on the fresh water pipeline and circulating fresh water in the fresh water circulation line;
A seawater conduit having a seawater intake part and a water discharge part;
A seawater pump located in the intake section of the seawater conduit;
A heat exchanger provided on the fresh water pipe and the sea water pipe, and for discharging heat of the fresh water in the fresh water pipe to the sea water pipe;
The nuclear power plant support vessel according to any one of claims 1 to 4, wherein: The cooling water supply equipment is
Water storage facilities;
A water pipe that can constitute a water supply line to the cooling facility by being connected to the cooling facility;
A transfer pump installed on the water pipeline and capable of supplying water stored in the water storage facility to the cooling facility;
The nuclear power plant support vessel according to any one of claims 1 to 5, wherein:   The nuclear power plant support vessel according to any one of claims 1 to 6, wherein the cooling water supply facility includes a seawater desalination facility.   The nuclear power plant support vessel according to any one of claims 1 to 7, comprising a heliport.

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