JP6348855B2 - Emergency core cooling system for nuclear power plants - Google Patents

Description

  The present invention relates to an emergency core cooling system for a nuclear power plant equipped with multiple water injection systems in order to inject reactor coolant into a reactor pressure vessel and achieve cold shutdown of the core.

  In a nuclear power plant, an event that should be assumed in evaluating the validity of the design from the viewpoint of safety is defined, and the accident of loss of reactor coolant is one of them.

  Reactor coolant loss accidents occur when reactor coolant flows out during reactor power operation due to damage or failure of piping or other equipment that forms the reactor coolant pressure boundary. This is an event where the cooling capacity of the reactor core decreases. Here, the reactor coolant pressure boundary is the same pressure condition as the reactor, including the reactor coolant during normal operation of the reactor, and severe conditions during abnormal transient changes and accidents during operation. This is a facility that forms a pressure barrier underneath, and if this breaks down, the reactor coolant is lost.

  Ensuring the safety of the reactor facility is to shut down the reactor safely, inject reactor coolant into the reactor pressure vessel, cool the reactor core, and confine radioactive material in the reactor containment vessel.

  Of these, cooling of the core is achieved by an emergency core cooling system. This emergency core cooling system is designed to prevent damage to the fuel cladding tube due to core cooling in the event of a loss of reactor coolant, maintain the integrity of the containment vessel, and remove the core decay heat over a long period of time. In addition, in the design of the emergency core cooling system, the safety function under a single failure of dynamic equipment is guaranteed, the installation of emergency diesel power generation facilities assuming the loss of in-house power supply and external power supply, and redundancy of functions and systems Securing gender and independence is considered. Here, the single failure means that one device loses a predetermined safety function due to a single cause, and includes multiple failures based on dependent factors.

  This emergency core cooling system is an improved boiling water reactor, and a high pressure core injection system that can inject reactor coolant even when the pressure inside the reactor pressure vessel is high, a reactor isolation cooling system, and a reactor pressure vessel It consists of a low-pressure water injection system that injects reactor coolant when the inside is at low pressure, and an automatic pressure reduction system that automatically depressurizes the reactor pressure vessel.

  FIG. 2 is a system schematic diagram of an emergency core cooling system in a conventional improved boiling water reactor. In this figure, first, the improved boiling water reactor is configured as follows.

  In FIG. 2, 3 is a reactor containment vessel, in which a reactor pressure vessel 2 for housing a core 4 is installed. A pressure suppression pool 11 is formed in the pressure suppression chamber 19 at the bottom of the reactor containment vessel 3 to store cooling water. Reference numeral 20 denotes a dry well indicating a portion other than the pressure suppression chamber 19 in the reactor containment vessel 3. Reference numeral 12 denotes a water supply pipe which guides the water supply to the reactor pressure vessel 2 by a reactor water supply pump (not shown). The water supply pipe is composed of two systems, 12A and 12B. Steam generated in the reactor pressure vessel 2 is sent to a steam turbine (not shown) via a main steam pipe 18.

  The emergency core cooling system 1 shown in FIG. 2 is divided into a section 1A, a section 1B, and a section 1C. The emergency core cooling system 1 is stored in the pressure suppression pool 11 by cooling pumps 5, 6, and 7 provided in these sections. The cooling water that is being supplied is sent to the reactor pressure vessel 2 to cool the core 4.

  The conventional emergency core cooling system 1 includes three series of low-pressure water injection systems (LPFL (A), LPFL (B), LPFL (C)) having a low-pressure water injection pump 5 (5A, 5B, 5C) driven by an electric motor 8. And two series of high-pressure core water injection systems (HPCF (B) and HPCF (C)) having a high-pressure core water injection system pump 6 (6B, 6C) driven by an electric motor 8 and a cooling system for reactor isolation driven by a steam turbine 9 A series of reactor isolation cooling system RCIC having a pump 7 and an automatic decompression system ADS are configured.

  These cooling systems are divided and arranged for each of Category 1A, Category 1B, and Category 1C. In Category 1A, a low-pressure water injection system LPFL (A) and a reactor isolation cooling system RCIC are arranged, and in Category 1B , A low pressure water injection system LPFL (B) and a high pressure core water injection system HPCF (B) are arranged, and a low pressure water injection system LPFL (C) and a high pressure core water injection system HPCF (C) are arranged in section 1C.

  Further, the emergency core cooling system 1 is used as an emergency power supply so that the safety function of this system can be achieved even if a single failure of the equipment constituting this system is assumed in addition to the case where an external power supply is not available. Electricity is supplied from three series of emergency diesel generators 8 (8A, 8B, 8C). As a result, section 1A composed of one series of low pressure water injection system LPFL (A), one series of reactor isolation cooling system RCIC and one series of emergency diesel generator 8A, and one series of low pressure water injection system LPFL Section 1B composed of (B), one series of high pressure core water injection system HPCF (B) and one series of emergency diesel generator 8B, one series of low pressure water injection system LPFL (C), and one series of high pressure cores A three-section configuration is made up of a section 1C composed of a water injection system HPCF (C) and a series of emergency diesel generators 8C.

  The low-pressure water injection system is one of the operation modes of the residual heat removal system among the above water injection systems, and is a system that absorbs the pool water in the pressure suppression pool 11 and injects the water outside the core shroud of the reactor pressure vessel 2. And consists of three independent lines (LPFL (A), LPFL (B), and LPFL (C)). Of the three low pressure water injection systems, the low pressure water injection system LPFL (A) in section 1A uses the water supply pipe 12A as the water injection route via the on-off valve 24, and the remaining sections 1B and 1C have low pressure water injection pipes 13 and 14 respectively. Use water injection piping.

  The high pressure core water injection system initially absorbs water from the condensate storage tank 15 as the first water source and finally from the pressure suppression pool 11 as the second water source, and injects the water into the core shroud of the reactor pressure vessel 2. It is composed of two independent series. In the sections 1B and 1C of this system, the high-pressure water injection pipes 16 and 17 are water injection routes, respectively.

  The reactor isolation cooling system RCIC initially absorbs water from the condensate storage tank 15 and finally from the pressure suppression pool 11 and injects water to the outside of the core shroud. This system uses the water supply pipe 12B as a water injection route.

  The automatic depressurization system ADS allows the steam in the reactor pressure vessel 2 to escape to the pressure suppression chamber 19, reduces the pressure in the reactor pressure vessel 2 to a pressure at which water can be injected by the low-pressure water injection system, and promotes core cooling. It is a system to do. For example, the pressure is released to the pressure suppression chamber 19 via a relief safety valve 27 provided in a part of the main steam pipe 18.

  The most severe assumption of the conventional emergency boiling water reactor emergency core cooling system 1 assumes the loss of on-site power supply and external power supply, and the emergency core cooling system of Category 1B or 1C cannot be used for any reason. In the following conditions, the remaining one of the water injection pipes 16 and 17 of the high pressure core water injection system will be considered. At this time, the reactor isolation cooling system pump 7 is activated, and the reactor coolant is injected into the reactor pressure vessel 2 that has become high pressure to alleviate the decrease in the reactor water level. Subsequently, the automatic depressurization system is activated, the relief safety valve 27 is opened, the pressure in the reactor pressure vessel 2 is lowered, and the low-pressure water injection system performs water injection.

  In addition to the most severe assumptions in the conventional emergency core cooling system 1 as described above, a situation is assumed in which one section cannot be used for some reason. In this case, as a new and most severe assumption, it is assumed that the in-house power supply and the external power supply are lost, and the emergency core cooling system of sections 1B and 1C becomes unusable for some reason. Consider damage to the water injection pipe 12A of the water injection system LPFL (A).

  That is, the state shown in FIGS. Of these, FIG. 3 shows the functions of the system configuration of the emergency core cooling system 1 organized by category. Category 1A is equipped with a reactor isolation cooling system pump RCIC (7), a low pressure injection pump LPLP (5A) and an emergency diesel generator DG (8A), and a high pressure core injection pump HPCF (6B), low pressure It is equipped with a water injection pump LPFL (5B) and an emergency diesel generator DG (8B). ). In addition, irrespective of these sections, it represents that an automatic pressure reducing system ADS for automatically reducing the pressure of the reactor pressure vessel is provided.

  In the situation assumed here, the core cooling system indicated by “x” in FIG. 3 cannot function. FIG. 4 shows a block diagram of an emergency reactor cooling system under conditions that are severer than expected in a conventional improved boiling water reactor. . Only the reactor isolation cooling system pump 7 and the emergency diesel generator 8A in section 1A and the automatic depressurization relief valve 27 that automatically depressurizes the reactor pressure vessel can function soundly. Even if the emergency diesel generator 8A is operable, the cooling water supplied by the low-pressure water injection pump 5A cannot contribute to the core cooling due to the damage of the water injection pipe 12A (water supply pipe).

  The cooling function based on the sound function in this state is considered as follows. At this time, the reactor isolation cooling system pump 7 is activated by the steam turbine, and the reactor coolant is injected into the reactor pressure vessel 2 that has become high pressure to alleviate the decrease in the reactor water level. Subsequently, the automatic depressurization system ADS is activated (the relief safety valve 27 is opened) to reduce the pressure in the reactor pressure vessel 2, but the reactor isolation cooling system RCIC is under the condition that the reactor pressure vessel 2 is at a low pressure. Since it cannot be used, and other cooling systems belonging to the emergency core cooling system 1 cannot be used, the cold shutdown of the core cannot be achieved.

  In response to this problem, Patent Document 1 discloses a design in which the reactor isolation cooling system RCIC of Category 1A is changed to a high pressure core water injection system that can be used even under low pressure conditions.

JP 2009-31079 A

  According to the solution proposed by Patent Document 1, it is possible to achieve cold shutdown of the core, but none of the cooling systems can realize cooling water injection into the core under the all-AC power loss SBO condition. In the case of existing equipment, it is necessary to perform significant removal and installation work. For this reason, it is desired to achieve a cold shutdown of the core by a technique that allows the cooling water to be injected into the core even under the all-AC power loss SBO condition, and by a simpler technique.

  In view of the above, the present invention provides a nuclear reactor capable of achieving a cold shutdown of a core in each system alone in an emergency core cooling system configuration including a reactor isolation cooling system.

  In order to solve the above-described problems, the present invention has an emergency core cooling system divided into at least three sections, and the first section of the emergency core cooling system includes a turbine-driven high-pressure water injection pump for isolation isolation. The system is composed of a low-pressure water injection system having an electric-driven low-pressure water injection pump and an emergency power supply. Water is supplied into the reactor pressure vessel via the first piping and the first water supply piping by the reactor isolation cooling system. , A nuclear power plant that supplies water into the reactor pressure vessel via the second pipe and the second water supply pipe by a low-pressure water injection system, and has an automatic pressure reduction system shared by the three-section emergency core cooling system 1, a first valve provided in a second pipe of the low-pressure water injection system, a first valve, and a first valve provided in the second pipe of the low-pressure water injection system. Upstream of the first pipe and the second pipe A tie line pipe connecting the pipe via a second valve is provided, the breakage of the second water supply pipe is detected by a breakage detection device, and the first valve and the second valve are operated. Water is supplied into the reactor pressure vessel through a tie line pipe and a first water supply pipe.

  According to the present invention, the water injection pipe of the water injection system of any one of the emergency core cooling systems that can be used under the condition that two of the emergency core cooling systems that are in three categories cannot be used for some reason. Provides an emergency core cooling system with multiple water injection systems so that even if a rupture occurs in the reactor, the reactor coolant can be injected into the reactor pressure vessel to achieve cold shutdown of the core. be able to.

The figure which shows the system | strain outline | summary of the improved boiling water reactor provided with the emergency core cooling system which concerns on the Example of this invention. The figure which shows the system outline | summary of the emergency core cooling system in the conventional improved boiling water reactor. The figure which arranged and showed the function of the system configuration of emergency core cooling system 1 for every division. The figure which shows the structure of the emergency reactor cooling system in the severest conditions in an improved boiling water reactor. The figure which showed centering on the additional component part of this invention. The figure which showed the specific measuring device installation position of the measuring instrument 22 (differential pressure gauge) which detects the fracture | rupture of 12 A of water supply piping. The figure which shows that fracture | rupture F of 12 A of water supply piping had arisen in the structure of FIG. The figure which shows the structural example of 2 out of 4 theory employ | adopted as the differential pressure gauge for the differential pressure measurement between water supply piping.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system schematic diagram of an improved boiling water reactor equipped with an emergency core cooling system according to an embodiment of the present invention.

  In FIG. 1, a part surrounded by a dotted line is a functional component added by the present invention. In short, in section 1A, the reactor isolation cooling system RCIC piping and the low pressure water injection system LPFL (A) piping are connected by a tie line 21 equipped with a controllable valve 23 to detect a breakage of the water supply piping 12A. When, for example, a differential pressure greater than a set value is generated between the pipes, the controllable valve 23 is controlled and opened.

  According to this configuration, the reactor isolation cooling system RCIC pump 7 is activated by the steam turbine 9 to inject the reactor coolant into the reactor pressure vessel 2 that has become high pressure to alleviate the decrease in the reactor water level. . Subsequently, the automatic depressurization system ADS is activated (the relief safety valve 27 is opened), and the pressure in the reactor pressure vessel 2 is reduced. Further, when the breakage of the water supply pipe 12A is detected (for example, a differential pressure greater than a set value is generated between the pipes), the controllable valve 23 is opened, and the low-pressure water injection pump 5A is driven by the startable motor 8A. Core water injection can be realized through the low-pressure water injection system LPFL (A), the tie line 21, and the water supply pipe 12B.

  The first embodiment of the present invention configured and used as described above will be described in detail below.

  First, the main configuration of the emergency core cooling system in the improved boiling water reactor of the embodiment is the same as that shown in FIG. The emergency core cooling system 1 includes three series of low-pressure water injection systems (LPFL (A), LPFL (B), LPFL (C)) having a low-pressure water injection pump 5 (5A, 5B, 5C) driven by an electric motor 8. Two series of high-pressure core water injection systems (HPCF (B), HPCF (C)) having a high-pressure core water injection system pump 6 (6B, 6C) driven by an electric motor 8 and a cooling system pump for isolating a reactor driven by a steam turbine 9 7 is composed of a series of reactor isolation cooling system RCIC 7 and an automatic decompression system ADS.

  These cooling systems are divided and arranged for each of Category 1A, Category 1B, and Category 1C. In Category 1A, a low-pressure water injection system LPFL (A) and a reactor isolation cooling system RCIC are arranged, and in Category 1B , A low pressure water injection system LPFL (B) and a high pressure core water injection system HPCF (B) are arranged, and a low pressure water injection system LPFL (C) and a high pressure core water injection system HPCF (C) are arranged in section 1C.

  Further, the emergency core cooling system 1 is used as an emergency power supply so that the safety function of this system can be achieved even if a single failure of the equipment constituting this system is assumed in addition to the case where an external power supply is not available. Electricity is supplied from three series of emergency diesel generators 8 (8A, 8B, 8C). As a result, section 1A composed of one series of low pressure water injection system LPFL (A), one series of reactor isolation cooling system RCIC and one series of emergency diesel generator 8A, and one series of low pressure water injection system LPFL Section 1B composed of (B), one series of high pressure core water injection system HPCF (B) and one series of emergency diesel generator 8B, one series of low pressure water injection system LPFL (C), and one series of high pressure cores A three-section configuration is made up of a section 1C composed of a water injection system HPCF (C) and a series of emergency diesel generators 8C.

  The low-pressure water injection system is one of the operation modes of the residual heat removal system among the above water injection systems, and is a system that absorbs the pool water in the pressure suppression pool 11 and injects the water outside the core shroud of the reactor pressure vessel 2. And consists of three independent lines (LPFL (A), LPFL (B), and LPFL (C)). Of the three low pressure water injection systems, the low pressure water injection system LPFL (A) in section 1A uses the water supply pipe 12A as the water injection route via the on-off valve 24, and the remaining sections 1B and 1C have low pressure water injection pipes 13 and 14 respectively. Water injection route.

  The high pressure core water injection system initially absorbs water from the condensate storage tank 15 as the first water source and finally from the pressure suppression pool 11 as the second water source, and injects the water into the core shroud of the reactor pressure vessel 2. It is composed of two independent series. In the sections 1B and 1C of this system, the high-pressure water injection pipes 16 and 17 are water injection routes, respectively.

  The reactor isolation cooling system RCIC initially absorbs water from the condensate storage tank 15 and finally from the pressure suppression pool 11 and injects water to the outside of the core shroud. This system uses the water supply pipe 12B as a water injection route.

  The automatic depressurization system ADS allows the steam in the reactor pressure vessel 2 to escape to the pressure suppression chamber 19, reduces the pressure in the reactor pressure vessel 2 to a pressure at which water can be injected by the low-pressure water injection system, and promotes core cooling. It is a system to do. For example, the pressure is released to the pressure suppression chamber 19 via a relief safety valve 27 provided in a part of the main steam pipe 18.

  The most severe assumption of the conventional emergency boiling water reactor emergency core cooling system 1 assumes the loss of on-site power supply and external power supply, and the emergency core cooling system of Category 1B or 1C cannot be used for any reason. In the following conditions, the remaining one of the water injection pipes 16 and 17 of the high pressure core water injection system will be considered. At this time, the reactor isolation cooling system pump 7 is activated, and the reactor coolant is injected into the reactor pressure vessel 2 that has become high pressure to alleviate the decrease in the reactor water level. Subsequently, the automatic depressurization system is activated, the relief safety valve 27 is opened, the pressure in the reactor pressure vessel 2 is lowered, and the low-pressure water injection system performs water injection.

  In addition to the most severe assumptions in the conventional emergency core cooling system 1 as described above, a situation is assumed in which one section cannot be used for some reason. In this case, as a new and most severe assumption, it is assumed that the in-house power supply and the external power supply are lost, and the emergency core cooling system of sections 1B and 1C becomes unusable for some reason. Consider damage to the water injection pipe 12A of the water injection system LPFL (A).

  In this case, as shown in FIG. 3, only one series of reactor isolation cooling system RCIC is in a state where water can be injected into the reactor pressure vessel 2.

  In the embodiment of the present invention, in addition to the above existing configuration, the following additional configuration is further provided. The portion surrounded by a circle in FIG. 1 is this additional portion, and FIG. 5 is an arrangement centering on the configuration of the additional portion. Therefore, the additional portion will be described with reference to FIG.

  FIG. 5 mainly describes the category 1A. Here, the connection pipe 31 to the water injection pipe (water supply pipe) 12A of the low pressure water injection system LPFL (A) and the connection pipe 32 to the water injection pipe (water supply pipe) 12B of the RCIC cooling system RCIC are connected by the tie line 21. It is connected. The tie line 21 is provided with a valve 23 that can be opened and closed (in FIG. 1, a motor-driven valve MO is provisionally described). In addition, a valve 24 that can be opened and closed is also provided in the connection pipe 31 of the low-pressure water injection system LPFL (A), but an existing valve can be used.

  Further, a meter 22 for measuring the state quantity (a differential pressure gauge is tentatively shown in FIG. 1) is connected to both the water supply pipes 12A and 12B, and the state quantity of the both water supply pipes 12A and 12B is connected to the meter 22. A breakage detection device 29 for identifying the breakage pipe based on is connected. Note that the example of FIG. 5 is an example in which a differential pressure detector is provided in the water supply pipes 12A and 12B in order to detect the broken pipe by the fracture detection device 29.

  The break detection device 29 detects the break F of the water supply pipe 12 </ b> A from the output of the meter 22 and operates the valve 23 on the tie line 21 and the valve 24 on the connection pipe 31. Thereby, the low pressure water injection system LPFL (A) can selectively perform water injection from the two pipes of the water supply pipe 12A and the water supply pipe 12B.

  For example, when a break is detected in the water supply pipe 12A, the break detection device 29 closes the valve 24 on the connection pipe 31 to the main pipe 12A and opens the valve 23 on the tie line 21. In this way, water can be injected into the core from the low pressure water injection system LPFL (A). In this case, the low pressure water injection pump 5A is started by the startable electric motor 8A, the valve 23 on the tie line 21 from the low pressure water injection system LPFL piping 31, the piping 32 of the reactor isolation cooling system RCIC and the water injection thereof. Water is poured into the core through the pipe (water supply pipe) 12B.

  Therefore, in the case of the emergency core cooling system of the embodiment, when for some reason two of the three emergency core cooling systems cannot be used and only one emergency core cooling system can be used, Furthermore, even if it is assumed that any one of the water injection pipes of the water injection system of the one-part emergency core cooling system that can be used is broken, the valve 23 on the tie line 21 and the valve 24 on the connection pipe are operated as necessary. By switching the water injection route of the 1A low-pressure water injection system, the reactor coolant having a stable flow rate can be injected into the reactor pressure vessel 2.

  In other words, even in the assumed event that is severer than the conventional one, it is possible to achieve a cold shutdown of the core by providing the injection system with multiplicity.

  In the present embodiment, an improved boiling water reactor has been described as an example, but the present invention can be applied to all nuclear reactors.

  In the embodiment described above, the following modifications and alternatives can be made. First, in the first embodiment, the openable / closable valve 24 on the tie line 21 between the low pressure water injection system of the section 1A and the reactor isolation cooling system RCIC is a motor driven valve, a compressed air driven valve, a nitrogen driven valve, a manual valve, etc. Any type can be applied.

The meter 22 for measuring the state quantities of both the water supply pipes 12A and 12B and detecting the breakage of the water supply pipes 12A and 12B can use either a differential pressure gauge, a differential flow meter, a thermometer, or a radiation measuring instrument. Any type.

  The difference between the reactor isolation cooling system RCIC side as the high pressure side and the low pressure water injection system side as the low pressure side as the instrument 22 for measuring the state quantities of both the water supply pipes 12A and 12B and detecting the breakage of the water supply pipe 12A. By using the pressure gauge, when the water supply pipe 12B breaks, it is possible to prevent the switching of the water injection route LPFL (A) of the low pressure water injection system which is not desired by downscaling.

FIG. 6 is a diagram showing a specific measuring instrument installation position of the measuring instrument 22 (differential pressure gauge) that detects the breakage of the water supply pipe 12A. Instrument installation position in this case, by setting both the water supply pipe 12A, the containment vessel 3 side of the rising portion 33 of the 12B of the reactor containment vessel 3, to give a large pressure difference in terms of hydrostatic head It is done.

  FIG. 7 is a diagram showing that the fracture F of the water supply pipe 12A has occurred in the configuration of FIG. In FIG. 7, the pressure at the pressure measurement point of the instrument 22 (differential pressure gauge) is PA and PB, and the pressure in the core is P0. In this case, the set differential pressure for switching the water injection route in section 1A is larger than the differential pressure ΔP1 between the two water supply pipes 12A and 12B at the normal time, and the vicinity of the reactor pressure vessel 2 in the water supply pipe 12A and the water supply pipe 12A. Is set to a value smaller than the pressure difference ΔP2 between the two water supply pipes 12A and 12B when the pipe fracture F occurs on the reactor pressure vessel 2 side of the rising portion 33A. As a result, undesired switching of the normal water injection route can be prevented, and in the assumed event of the present invention, the differential pressure can be detected and the water injection route can be switched even when fractures are assumed at most positions on the water supply pipe 12A.

  In the configurations of FIGS. 6 and 7, a shock wave may be generated immediately after the rupture occurs in any of the ruptures of both the water supply pipes 12 </ b> A and 12 </ b> B. In this case, accurate measurement of the differential pressure between the two water supply pipes 12A and 12B becomes difficult due to the influence of this shock wave. For this event, by installing a timer in the rupture detection device 29 so as to operate, for example, several tens of seconds after the rupture, undesired switching of the water injection route due to inaccurate differential pressure measurement can be prevented.

  Further, in the configurations of FIGS. 6 and 7, multiplexing of measuring instruments or the like is effective for improving the reliability of measurement. FIG. 8 shows an example of the position configuration in this case. In FIG. 8, four differential pressure measuring instruments 22 (22a, 22b, 22c, 22d) are installed, and the break detection device 29 adopts the 2 out of 4 theory for the signals of the four differential pressure gauges. The probability of preventing erroneous measurement can be improved.

1: Emergency core cooling system 2: Reactor pressure vessel 3: Reactor containment vessel 4: Core 5: Low pressure water injection system pump 6: High pressure core water injection system pump 7: Reactor isolation cooling system pumps 8A, 8B, 8C: Emergency diesel generator 9: Steam turbine for cooling system pump drive at reactor isolation 11: Pressure suppression pool 12A, 12B: Feed water piping LPFL (A), LPFL (B), LPFL (C): Low pressure water injection system HPCF (B ), HPCF (C): high pressure water injection system RCIC: reactor isolation cooling system 13, 14: low pressure flowing water injection pipe 15: condensate storage tank 16, 17: high pressure core water injection pipe 18: main steam pipe 19: Pressure suppression chamber 20: Dry well 21: Tie line 22 between low pressure water injection system LPFL (A) and reactor isolation cooling system 22: Break detection instrument 23: Water injection route switching valve 24 of low pressure water injection system LPFL (A): Low pressure On-off valves 33A, 33B on the connection pipe of the water system LPFL (A) to the water supply pipe 12A: Water supply pipe rising section 27: Relief safety valve 29: Break detection device 31: Water injection pipe (water supply pipe) of the low pressure water injection system LPFL (A) Connection pipe 32 to 12A: Connection pipe to the water injection pipe (water supply pipe) 12B of the RCIC cooling system RCIC

Claims (11)

The emergency core cooling system has at least three sections, and the first section of the emergency core cooling system has a low pressure having a reactor isolation cooling system having a turbine-driven high-pressure water injection pump and an electrically driven low-pressure water injection pump. Consists of a water injection system and an emergency power supply, water is supplied into the reactor pressure vessel via the first piping and first water supply piping by the reactor isolation cooling system, and the second piping is supplied by the low pressure water injection system. An emergency core cooling system of a nuclear power plant that supplies water into a reactor pressure vessel via a second water supply pipe and has an automatic pressure reducing system shared by the three divided emergency core cooling systems. And
A break detection device for detecting breakage of the first water supply pipe or the second water supply pipe, a first valve provided in a second pipe of the low-pressure water injection system, and an upstream side of the first valve; A tie line pipe connecting the first pipe and the second pipe via a second valve;
The rupture detection device detects a rupture of the second water supply pipe, operates the first valve and the second valve, and connects the tie line pipe and the first water supply pipe from the low pressure water injection system. An emergency core cooling system for a nuclear power plant characterized in that water is supplied into the reactor pressure vessel via An emergency core cooling system for a nuclear power plant according to claim 1,
The first-section emergency core cooling system supplies the water into the reactor pressure vessel via the first piping and the first feed water piping by the reactor isolation cooling system, and the three-section emergency core cooling system. An automatic depressurization system shared by the core cooling system is operated, and after depressurization in the reactor pressure vessel, water is supplied into the reactor pressure vessel from the low-pressure water injection system via the tie line piping and the first water supply piping. An emergency core cooling system for nuclear power plants. An emergency core cooling system for a nuclear power plant according to claim 1 or 2,
Among the three-sectioned emergency core cooling systems, the emergency core cooling systems other than the first section include a high-pressure core injection system that can inject reactor coolant even when the inside of the reactor pressure vessel is at a high pressure, It consists of a low-pressure water injection system that injects reactor coolant when the pressure inside the reactor pressure vessel is low,
The low pressure water injection pump of the first section is a situation in which the in- house power supply and the external power supply are lost, and the cooling by the emergency core cooling system other than the first section becomes unusable for some reason , and the second section An emergency core cooling system for a nuclear power plant that can be used even when the water supply pipe is broken. An emergency core cooling system for a nuclear power plant according to any one of claims 1 to 3,
As the first valve and the second valve, openable motor driven valve, compressed air driven valves, nitrogen driven valve, emergency core cooling system of a nuclear power plant, characterized in that it comprises either manual valve . An emergency core cooling system for a nuclear power plant according to any one of claims 1 to 4,
A breakage detection device for detecting breakage of the first water supply pipe or the second water supply pipe is provided between the first water supply pipe and the second water supply pipe and measures a state quantity in the water supply pipe. An emergency core cooling system for a nuclear power plant characterized in that it uses a signal from a measuring instrument and includes any one of a differential pressure gauge, a differential flow meter, a thermometer, and a radiation measuring instrument . An emergency core cooling system for a nuclear power plant according to claim 5, wherein a differential pressure gauge is used as the rupture detection device ,
The differential pressure gauge is formed with the reactor isolation cooling system side as the high pressure side and the low pressure water injection system side as the low pressure side, and the set differential pressure for switching the water injection route is larger than the normal pressure difference, and the pipe breaks. By setting to a value smaller than the differential pressure at the time of occurrence, when the first water supply pipe is broken, the water injection route of the low pressure water injection system is not switched by the downscale of the differential pressure gauge output. An emergency core cooling system for nuclear power plants. An emergency core cooling system for a nuclear power plant according to claim 5 or 6, wherein a differential pressure gauge is used as the rupture detection device .
The differential pressure gauge is in a nuclear reactor containment vessel, and differential pressure is measured on the reactor containment vessel side from the rising portions of the first water supply pipe and the second water supply pipe. Emergency core cooling system. The emergency core cooling system for a nuclear power plant according to any one of claims 5 to 7, wherein a differential pressure gauge is used as the rupture detection device .
The differential pressure gauge sets the set value of the water injection route switching differential pressure to be equal to or higher than the pressure difference between the first water supply pipe and the second water supply pipe during normal operation, and the water injection route is not switched during normal operation. An emergency core cooling system for nuclear power plants. An emergency core cooling system for a nuclear power plant according to claim 8, wherein a differential pressure gauge is used as the rupture detection device .
The differential pressure gauge is capable of detecting a differential pressure even when a pipe breakage is assumed in the vicinity of the reactor pressure vessel in the second water supply pipe and on the reactor pressure vessel side from the rising portion of the second water supply pipe. An emergency core cooling system for nuclear power plants, which is possible. An emergency core cooling system for a nuclear power plant according to any one of claims 1 to 9,
The rupture detection device has a relaxation time after rupture so that the rupture detection device does not cause an erroneous operation even if a shock wave that may occur immediately after the first water supply pipe or the second water supply pipe is ruptured is taken into account. An emergency core cooling system for a nuclear power plant, comprising a timer set to operate after passing through. The emergency core cooling system for a nuclear power plant according to any one of claims 1 to 10, wherein a differential pressure gauge is used as the rupture detection device .
The differential pressure gauge employs a 2 out of 4 theory to prevent erroneous measurement, and an emergency core cooling system for a nuclear power plant.

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