LT6317B - Emergency core cooling system of nuclear power plant - Google Patents

Abstract

To provide a reactor capable of achieving cold shutdown of a reactor core by each single system in a configuration of an Emergency Core Cooling System (ECCS) including a Reactor Core Isolation Cooling system (RCIC). In an ECCS of a nuclear power plant including ECCSs sectioned into at least three sections, in which a first section in the ECCSs has a RCIC having a high-pressure injection pump driven by a turbine, a Low Pressure Flooder system (LPFL) having a low-pressure injection pump driven by a motor and an emergency power source, water is supplied into a reactor pressure vessel (RPV) through a first pipe and a first feedwater pipe by the RCIC, and water is supplied into the RPV through a second pipe and a second feedwater pipe by the LPFL, and an Automatic Depressurization System (ADS) which is used in common by the ECCSs sectioned into three sections, the ECCS includes a fracture detector detecting a fracture in the first feedwater pipe or the second feedwater pipe, and a first valve provided in the second pipe of the LPFL and a tie-line connecting the first pipe and the second pipe through a second valve in an upstream side of the first valve, in which the fracture detector detects a fracture of the second feedwater pipe and operates the first valve and the second valve to supply water into the RPV from the LPFL through the tie line and the first feedwater pipe.

Description

Technical field

The present invention relates to a nuclear power plant core-area emergency cooling system (AZAAS), including back-up injection systems for injecting coolant into a reactor pressure vessel (RSI) for cold shutdown of a reactor.

State of the art

The occurrences within a nuclear power plant that are to be considered when assessing the suitability of the design are defined for safety purposes and include the refrigerant loss accident (APA).

APA is an event in which reactor coolant leaks and the cooling capacity in the reactor core is reduced due to reactor coolant pressure pipes or emergency equipment breakage, cracking or similar. Here, the reactor coolant pressure barrier corresponds to measures under the same pressure conditions as the reactor, retaining the reactor coolant during normal reactor operation and forming a pressure barrier, critical conditions during reactor short-term anomaly processes or accidents, and happen in APA.

To ensure the safety of the reactor equipment, the reactor is safely shut down and the reactor core is cooled by injecting coolant into the reactor RSI to retain radioactive materials within the primary containment (PRT).

In the aforementioned processes, the reactor core is cooled using AZAAS. AZAAS is designed to prevent damage to the fuel cell jacket tubes, to ensure PRT integrity, and to remove residual heat from the reactor over an extended period of time by cooling the reactor core in the case of APA. In addition, the AZAAS design provides a safety function in the event of a single active component failure and provides for the installation of an emergency diesel generator (ADG), assuming that both local and external power sources can be lost, and provides for duplication or autonomy of functions and systems. . Here, a single malfunction means the loss of the safety function of an individual component due to a single factor, including multiple malfunctions due to its dependent factors.

In the Advanced Boiling Water Reactor (ABWR), AZAAS includes the High Pressure Reactor Injection Molding System (ASAZUS) and the Reactor Core Isolation Cooling System (RAZIAS), which allows the reactor coolant to be injected even when the RSI is in a high pressure state; a Low Pressure Injection System (HES) to inject reactor coolant when the RSI is at low pressure; and Automatic Pressure Relief System (ASMS), which automatically reduces the pressure on the RSI.

FIG. 2 is a schematic diagram of a modern ABWR reactor AZAAS 1 system. In the drawing, the structure of the ABWR reactor is as follows.

Position "3" FIG. 2 is the RSI protecting the reactor core 4. The pressure relief chamber at the bottom of the PRT 3 has a pressure relief basin (SMB) 11 for storing cooling water. Position "20" denotes a dry shaft corresponding to section 19 other than SMK inside PRT 3. Position "12" represents the feed water pipe supplying water to the RSI 2 via a non-shown reactor feed pump. The feed water pipe includes two systems, 12A and 12B. The steam generated inside the RSI 2 is fed to an unshared steam turbine by a main steam pipe 18.

FIG. 2 shows AZAAS 1 divided into sections 1A, 1B and 1C supplying cooling water stored in SMB 11 to RSI 2 by cooling pumps 5, 6 and 7 arranged in these sections, thereby cooling the reactor core 4.

The AZAAS 1 of modern ABWR reactors includes three HRC systems (HRC (A), HRC (B) and HRC (C)) with HRC pumps 5 (5A, 5B and 5C) driven by motors 8, here are two ASAZUS (ASAZUS (B) ) and ASAZUS (C)) systems with ASAZUS pumps 6 (6B and 6C) powered by engines 8, one RAZIAS system with RAZIAS pump 7 driven by steam turbine 9, and ASMS.

Said cooling systems are individually arranged to meet sections 1A, 1B and 1C. HRC (A) and RAZIAS are installed in Section 1A, HRC (B) and ASAZUS (B) are installed in Section (B), and HRC (C) and ASAZUS (C) are installed in Section (C).

AZAAS 1 receives power from three ADGs (8A, 8B, and 8C) as emergency power sources to provide a safety function even in the event of an external power failure and a single system component failure. Accordingly, the system is comprised of three sections, each of which, in Section 1A, is a JSUS (A) system, one RAZIAS system, and one ADG 8A; Section 1B has one JSUS (B), one ASAZUS (B) and one ADG 8B, and Section 1C has one JSUS (C), one ASAZUS (C) and one ADG 8C.

HRC in the injection system configuration corresponds to one of the operating modes in the residual heat removal system (LFA), where the system pumps water from the SMB 11 basin and sprays this water outside the RSI core. The HRC comprises three independent systems (HRC (A), HRC (B) and HRC (C)) arranged in three sections: HRC (A) in section 1A uses a feedwater pipe 12A as an injection line through a controlled valve 24 and HRC injection 13 and 14 are used as injection pipes in the remaining sections 1B and 1C.

ASAZUS is a system that pumps water, which first draws water from a condensate storage tank (PRC) 15 as the first water source and then SMB 11 as the second water source by injecting water inside the RSI 2 core zone shell with two independent systems. ASAZUS injection pipes 16,17 are used as injection lines in sections 1B and 1C of the system.

RAZIAS first pumps water from PRC 15 and finally SMB 11 by spraying water outside the core. The supply water pipe in the 12B system is used as an injection line.

The ASMS is a system that releases vapor inside RSI 2 to SMK 19, reducing the pressure inside RSI 2 to a pressure at which injection can be made by HRC, with additional cooling of the reactor core. The steam is discharged into the SMK 19 via the safety valve AV 27 provided, for example, at the main steam pipe 18.

The most unfavorable assumption for AZAAS 1 in existing ABWR reactors is the foreseeable loss of a local power source and an external power source, as well as a mode where AZAAS sections 1B or 1C fail for some reason and are considered to be any of the remaining injection tubes 16 or 17. There are irregularities in the ASAZUS system. In this case, the RAZIAS pump 7 is started and the reactor coolant is injected into the RSI 2 at high pressure, thus mitigating the drop in reactor water level. The ASMS is then triggered to open the AV 27, which relieves the pressure inside the RSI 2, and then sprayed with the HRC.

Without making the most unfavorable assumption about AZAAS 1 in modern times

In ABVVR reactors, there may be an imaginary situation where, for some reason, one additional section does not work. In this case, both the indigenous energy source and the external energy source are considered as a new critical assumption; and that, for some reason, sections 1B and 1C of AZAAS, and additionally sectional 1A injected tube 12A are damaged.

In other words, it is assumed that there is a situation depicted in FIG. 3 and FIG. In the 4 drawings. The functions of the components of the AZAAS (1) system are shown in Figs. 3, by distributing the functions through the respective sections. RAZIAS pump 7 and JISUS pump 5A and ADG 8A are provided in section 1A, ASAZUS pump 6B and JASUS pump 5B and ADG 8B are provided in section 1B, and ASAZUS pump 6C and JSUS pump 5C and ADG 8C are provided in section 1C. The drawing shows that ASMS, which automatically reduces RSI pressure, exists independently of these sections.

Functions of the active zone cooling system of the situation under consideration are shown in Figs. 3 "X" does not work. A schematic diagram of the AZAAS configuration under more severe conditions than expected in existing ABVVR reactors is shown in Figs. 4, where "X" is used to indicate locations where malfunctions occur. Only the RAZIAS pump 7 and ADG 8A in section 1A and the ASMS AV 27 work reliably, which automatically reduces RSI pressure. Although the ADG 8A could operate, the cooling water supplied by the HSE pump 5A does not contribute to the cooling of the reactor core due to a defective injection tube 12A (feed water pipe).

Cooling that can be trusted in these conditions should be such. In this case, the steam turbine starts the RAZIAS pump 7, which injects the reactor coolant into the RSI 2 at high pressure to mitigate the drop in water level in the reactor. The ASMS (AV 27 open) then activates, reducing the pressure inside the RSI 2, but the RAZIAS does not work under conditions where the RSI 2 is in a low pressure state and other cooling systems belonging to AZAAS 1 also fail, resulting in a cold shutdown of the reactor core. hard to reach.

In view of the above problems, the patent literature describes a design in which the RAZIAS section (1A) is replaced by an ASAZUS that can operate under low pressure conditions.

List of links:

Patent Literature: JP-A-2009-31079

The essence of the invention

Technical problem

According to the solution proposed in JP-A-2009-31079, a cold shutdown of the reactor core is possible, but no cooling system operates to inject cooling water into the core of the reactor under power failure (EMJN) conditions. In addition, large-scale removal and installation work is required on existing installations. Accordingly, it is desirable to achieve a cold shutdown of the reactor core by such methods that it is possible to inject cooling water into the core of the reactor, even under EMJN conditions and in a simpler manner.

In view of the foregoing, the present invention provides a reactor capable of achieving cold shutdown of the reactor core in each individual system of the AZAAS configuration, including RAZIAS.

Solving the problem

According to an embodiment of the present invention, to solve the problem, AZAAS nuclear power plants are proposed, comprising AZAAS systems divided into at least three sections, wherein the first section of the AZAAS system comprises a RAZIAS with a high pressure injection pump driven by turbines; HPS with the low pressure injection pump driven by the engine and the emergency power source where RAZIAS supplies water to the RSI by the first pipe and the first feed water pipe, and the HFSU supplies the water to the RSI by the second pipe and the second feed water pipe; and the ASMS, used jointly by AZAAS, is divided into three sections, which include a crack detector for detecting cracks in the first feed water pipe or the second feed water pipe, and providing a first valve in the HRS second pipe and a connecting line connecting the first pipe and the second pipe a second valve upstream of the first valve, wherein the crack detector detects cracks in the second feed water pipe and actuates the first and second valves to supply water to the RSI from the HRC through the interconnection line and the first feed water pipe.

Advantages of the Invention

The present invention provides an AZAAS that allows injection systems to have a reserve to inject reactor coolant into the RSI and achieve a cold shutdown of the reactor core under conditions where for some reason the emergency cooling systems do not operate in two of the three AZAAS sections. it is assumed that a crack has occurred in the injection tube in any section of the AZAAS injection system that can be used.

Brief description of the drawings

FIG. 1 is a diagram showing an ABWR including AZAAS in accordance with an embodiment of the present invention.

FIG. 2 shows a schematic diagram of an existing ABWR AZAAS configuration.

FIG. 3 is an illustration showing the functions of the components of the AZAAS 1 system, broken down by respective sections.

FIG. 4 is a diagram depicting the AZAAS configuration in ABWR under most adverse conditions.

FIG. 5 is a diagram substantially depicting additional components of the present invention.

FIG. 6 shows a special measuring device (pressure gauge) in position 22 for detecting cracks in the feed water pipe 12A.

FIG. 7 shows how a crack F in the feed tube 12A occurs in FIG. 6 in the configuration shown.

FIG. Fig. 8 is a diagram illustrating an example of a "2 of 4" configuration for a pressure difference gauge measuring the pressure difference between the feed water pipes.

Description of Embodiments of the Invention

The invention will now be explained in more detail with reference to the drawings.

Option 1

FIG. 1 is a schematic diagram of an ABWR comprising AZAAS according to an embodiment of the present invention.

FIG. The dotted lines of parts 1 represent the functional configuration parts added in accordance with the present invention. In short, the connecting line 21 comprising the controlled valve 23 in section 1A connects the RAZIAS pipe and the JUSS (A) pipe and the controlled valve 23 is operated such that it is opened when a crack is detected in the feed water pipe 12A, for example. differential pressure of a given set point or greater.

In the given configuration, the steam turbine 9 runs a RAZIAS pump 7, which injects the reactor coolant at high pressure into the RSI 2 to mitigate the drop in the reactor water level. It then triggers ASMS (AV 27 open) to reduce the pressure inside the RSI 2. In addition, when a rupture in the feed water pipe 12A is detected (for example, a set pressure of a certain size or greater between the pipes), a controlled valve 23 is opened and an ADG 8A driven FUEL pump 5A can be started by spraying water into the reactor core. connecting line 21 and supply water pipe 12B.

Embodiment 1 of the embodiment of the present invention used as described above will be explained in more detail below.

In this embodiment, the main AZAAS components of the ABWR reactor are the same as those shown in Figs. 2. The AZAAS 1 comprises three RIS systems (RIS (A), RIS (B) and RIS (C)) having RIS pumps 5 (5A, 5B and 5C) powered by ADG 8; two ASAZUS systems (ASAZUS (B) and ASAZUS (C)) having ASAZUS pumps 6 (6B, 6C) powered by ADG 8, one RAZIAS system with a RAZIAS pump 7 driven by a steam turbine 9, and ASMS.

These cooling systems are arranged separately to accommodate section 1A, section 1B and section 1C. JSUS (A) and RAZIAS are installed in section 1A; HRC (B) and ASAZUS (B) are installed in section (B), and HRC (C) and ASAZUS (C) are installed in section (C).

AZAAS 1 receives power from three ADG systems (8A, 8B and 8C) as emergency power systems to provide a safety function even in the event of a power failure from an external power source and in the event of a single failure of a component in the system. Accordingly, the system is configured with three sections, wherein Section 1A comprises one JSUS (A) system, one RAZIAS system and one ADG 8A, Section 1B comprises one JSUS (B), one ASAZUS (B) system, and one ADG 8B, and 1C. section includes one JSUS (C) system, one ASAZUS (C) system and one ADG 8C.

In the injection system configurations, HSS is one of the operating modes of the LPS for pumping water from the SMB 11 basin to the outside of the RSI 2 core, including three independent HSS systems (HSS (A), HSS (B) and HSS (C) ). The three-section HRC system in the HRC (A) section 1A uses a feedwater pipe 12A as an injection line with a controlled valve 24, while the HRC pipes 13 and 14 are used as an injection line in sections 1B and 1C.

ASAZUS is a system that pumps water from PRC 15 as the first source of water, then SMB 11 as the second source of water, injects water into the RSI 2 core of the shell, comprising two independent systems. ASAZUS pipes 16 and 17 are used as injection lines in system sections 1B and 1C.

RAZIAS first pumps water from PRC 15 and finally from SMB 11 by injecting water outside the core. The supply water pipe in the 12B system is used as an injection line.

The ASMS is a system that releases steam inside RSI 2 to SMK 19, reducing the pressure inside RSI 2 to a pressure at which HRC can spray coolant for additional cooling of the reactor core. Steam is discharged to SMK 19 via AV 27 provided, for example, at portion 18 of the main steam pipe.

For existing ABWR reactors, the most unfavorable assumption for AZAAS 1 would be the loss of the system's internal power source and external power source, as well as the failure of the AZAAS system in Sections 1B and 1C for any reason, in addition to any further damage to ASAZUS injection tubes 16 or 17. At this point, the RAZIAS pump 7 is started, and the reactor coolant is injected into the RSI 2 under high pressure, thereby mitigating the drop in reactor water level. The ASMS is then triggered to open the AV 27, which relieves the pressure inside the RSI 2, and then sprays with the HRC.

In addition to the most unfavorable assumption regarding the AZAAS 1 system in existing ABWR reactors, there is also a situation where, for some reason, an additional section does not work. In this case, the loss of the internal power source and the external power supply as well as the fact that, for some reason, sections 1B and 1C of the AZAAS systems and, in addition, section 1A, the system's INJECTOR (A) injection pipe 12A, are broken.

In this case, only one RAZIAS system can inject reactor coolant into RSI 2 as shown in FIG. 3.

In an embodiment of the present invention, in addition to the above-mentioned existing components, the following additional components are provided. The circles defined in Figs. Parts 1 are additional parts, and Figs. 5 essentially depicts referenced components in additional parts.

Additional parts will be explained with reference to Figs. 5.

Section 1A is substantially explained in FIGS. 5. In this case, the pipe 31 connecting to the JSUS (A) injection pipe (supply water pipe) 12A and the pipe (32) connecting to the RAZIAS injection pipe (feeding water pipe) 12B are connected by a connecting line 21. The connecting line 21 is a control valve 23 is provided (a motor-driven valve (MO), which is dotted in Figure 1). In addition, the controlled valve 24 is also provided in the HRC (A) connecting pipe 31. The existing valve may be used as a valve 24.

A device 22 for measuring status indicators (the pressure difference gauge is dotted in Fig. 1) is connected to both supply pipes 12A and 12B, and a crack detector 29 for detecting cracks in the pipes based on the status indicators of both supply pipes 12A and 12B is connected to the device. 22. In Example 5, a differential pressure detector is provided in the feedwater pipes 12A and 12B to detect cracks in the pipes 12A and 12B.

The rupture detector 29 detects a rupture F in the feed water pipe 12A according to the device 22 by controlling valve 23 in the connecting line 21 and valve 24 in the connecting pipe 31. Accordingly, JSUS (A) can selectively inject water from two feed water pipes 12A and 12B.

For example, when a rupture in the feed water pipe 12A is detected, the rupture detector (29) operates such that valve 24 in pipe 31 connecting to pipe 12A is closed and valve 23 in pipe 21 is opened. In this way, it is possible to inject water into the reactor core from the IBS (A). In this case, the HSS pump 5A is driven by an ADG 8A, which can be switched on, and water is injected into the reactor core from the HSS tube 31 through valve 23 in the interconnection 21, through the RAZIAS tube 32 and the injection (feed water) tube 12B.

Accordingly, when for some reason two of the three AZAAS sections are inoperative and only one AZAAS section is in operation, even if it is additionally assumed that any injection system has a crack in the injection tube within the AZAAS one section that can be used , stable reactor coolant flow may be injected into RSI 2 by switching the spray stroke on the AZAAS system in the JSUS system section 1A, adjusting valve 23 in the connection line 21 and valve 24 in the connecting pipe, if necessary according to an embodiment of the invention.

That is, cold shutdown of the reactor core can be achieved even under more severe conditions than in the ABWR reactor mentioned above, provided that the injection systems contain reserve / duplication.

Although the embodiment of the invention has been explained based on the example of ABWR, the present invention is applicable to all reactors.

In the embodiment described above, further modifications and alternatives may be applied. First, in an embodiment of the present invention, a motor-controlled valve, a compressed air-operated valve, a nitrogen-driven valve, or a manually operated valve may be applied as a controlled valve 24 in the connection line 21 between the HRC and the RAZIAS in section 1A.

Devices such as pressure difference gauge, flow difference gauge, thermometer and radiation density gauge, regardless of their type, may be used to detect cracks in the feed water pipes 12A and 12B as a device 22 for measuring the status indicators of both feed water pipes 12A and 12B.

When the pressure difference gauge configured to set RAZIAS side as high pressure side and HRT side as low pressure side is used as a device 22 to measure the status indicators of both feedwater pipes 12A and 12B to detect cracks in feedwater pipe 12A, it is possible to avoid unwanted SHIFT system Shifting the spray stroke of the SHIFT (A), proportionally reducing the value if the supply water pipe 12B is missing.

FIG. 6 shows a special installation location of a measuring device 22 (pressure difference gauge) for detecting cracks in the feed water pipe 12A. In this case, when the measuring device is located closer to the side of PRT 3, a greater difference in pressure in terms of static pressure can be obtained in both risers 33 of the feed water pipes 12A, 12B in the reactor pressure vessel RSI (2).

FIG. 7 is a view showing FIG. 6 shows a crack F in the feed water pipe 12A. FIG. At the pressure measurement points of the device 22 (pressure difference gauge) 7, the pressures are PA, PB and the pressure inside the reactor core, PO. In this case, the pressure difference to be set for switching the injection line in section 1A is set greater than the pressure difference ΔΡ1 between the two supply water pipes 12A and 12B in the normal state or less than the pressure difference ΔΡ2 between the two supply water pipes 12A and 12B. when the tube bursts 12A in the environment of the reactor pressure vessel RSI (2) and also on the RSI 2 side of the portion 33A rising from the feed water 12A tube. Therefore, undesirable switching of the injection line in the normal state is not possible and the pressure difference can be detected and the switching of the injection line can occur even if a crack occurs in many locations of the feed water pipe A12 in the states of the present invention.

FIG. 6 and FIG. In the configuration shown in Fig. 7, a shock wave may occur immediately after a crack occurs at any possible crack in both feed water pipes 12A and 12B. In this case, the effect of the shock wave makes it difficult to accurately measure the pressure difference between the two supply water pipes 12A and 12B. In response to an event, the timer 29 of the crack detector is set to operate, for example, several tens of seconds after the crack, thereby avoiding undesired injection line switching due to inaccurate differential pressure measurement.

In addition, FIG. 6 and FIG. In the configuration shown in Fig. 7, it is efficient to duplicate the measuring devices and the other to improve the reliability of the measurements, and in this case an example of the configuration of the locations is shown in Figs. 8. In the example of FIG. 8 is equipped with four differential pressure gauges 22 (22a, 22b, 22c and 22d) and a "2 of 4" criterion applied to the crack detector 29 for signals from the four differential gauges. This increases the reliability of the differential pressure gauges, avoiding erroneous measurements.

List of positions

1: Core Emergency Cooling System (AZAAS);

2: Reactor Pressure Vessel (RSI);

3: Primary Reactor Hood / Shell (PRK);

4: reactor core;

5: Low Pressure Injection System (HRC) pump;

6: High Pressure Core Injection System (ASAZUS) pump;

7: reactor core isolation cooling system (RAZIAS) pump;

8A, 8B, 8C: Emergency Diesel Generators (ADG);

9: steam turbine for driving the RAZIAS pump;

11: Pressure Relief Pool (SMB);

12A, 12B: Feed water pipes;

HRC (A), HRC (B), HRC (C): low pressure flood systems;

ASAZUS (B) and ASAZUS (C): High Pressure Core Flow Systems;

RAZIAS: Reactor core isolation cooling system;

13, 14: HSS injection pipes;

15: Condensate Storage Capacity (KLT);

16, 17: ASAZUS injection pipes;

18: Main steam pipe;

19: Pressure Relief Chamber (SMK);

20: Dry Shaft;

21: Line connecting RIS (A) and RAZIAS;

22: device for detecting cracks;

23: Valve JSUS (A) for switching the spray line;

24: a controlled valve in the pipe connecting to the feed water pipe (12A) of the HRC (A);

33A, 33B: Rising parts of the feed water pipe;

27: Safety valve (overpressure) (AV);

29: Crack Detector;

31: a pipe connecting to the injection tube (feed water pipe) of the HSS (A) (12A);

32: Pipe Connecting to RAZIAS Injection Pipe (Feed Water Pipe) (12B).

Claims (11)

1. Nuclear power plant core-area emergency cooling system (AZAAS), comprising: divided into at least three sections AZAAS, the first section AZAAS comprising a reactor core isolation cooling system (RAZIAS) having a turbine (9) driven high pressure injection pump (7); a low pressure injection system (HRS) with a motor-driven low pressure injection pump (5A) and an emergency power supply (8A), wherein the RAZIAS supplies water to the reactor pressure vessel (RSI) by a first pipe (32) and a first feed water supply pipe (32). 12B), and the HSSF supplies water to the RSI by means of a second pipe (31) and a second supply water supply pipe (12A), and an automatic pressure relief system (ASMS) used in conjunction with AZAAS, divided into three sections. : a crack detector (29) for detecting cracks in the first feed water supply pipe (12B) or the second feed water supply pipe (12A); a first valve (24) provided in the second tube (31) of the HRC; and a connecting line (21) connecting the first pipe (32) and the second pipe (31) through a second valve (23) upstream of the first valve (24), wherein the crack detector (29) is for detecting cracks in the second supply water pipe (29). 12A) and controlling the first valve (24) and the second valve (23) to supply water to RSI from HRC through interconnection line (21) and first feed water pipe (12B). 2. The nuclear power plant AZAAS according to claim 1, characterized in that in the first section AZAAS supplies water to the RSI first pipe (32) and the RAZIAS first feed water pipe (12B), controls the ASMS for use with the AZAAS divided into three sections, and , by reducing the pressure on the RSI, supplies water from the HRC to the RSI via a connecting line (21) and a first feed water pipe (12B). 3. The nuclear power plant AZAAS according to claim 1 or 2, characterized in that the AZAAS systems other than the first section of the AZAAS system divided into three sections include high-pressure reactor core flooding systems (ASAZUS) which can inject reactor coolant even when RSI ( ) with high pressure inside, and HRC systems () injecting coolant into the reactor when the RSI is low pressure, and a first-section low-pressure injection pump (5A) that can be used even when cooling in systems other than the first-section AZAAS difficult to execute, and when a crack in the second supply water pipe (12A) occurs. The AZAAS nuclear power plant according to any one of claims 1 to 3, wherein any of the motor-controlled valves, which may be open and closed, a compressed air valve, a nitrogen valve or a manually operated valve is provided as the first valve ( 24) or a second valve (23) that can be operated. The nuclear power plant AZAAS according to any one of claims 1 to 4, characterized in that the crack detector (29) which detects a crack in the first feed water pipe (12B) or the second feed water pipe (12A) uses a device (22) between the first supply water pipe (12B) and the second supply water pipe (12A), the signal and measures the status indicators inside the supply water pipes, and said device (22) may include any pressure difference meter, flow difference meter, thermometer and radiation density meter . 6. The nuclear power plant AZAAS according to claim 5, characterized in that the pressure difference gauge is formed by detecting the RAZIAS () side as the high pressure side and the HRUS side as the low pressure side, and the injection line in the HRU system is not switched by reducing the flow. the feed water pipe (12A) is cracked. 7. The nuclear power plant AZAAS according to claim 5 or 6, characterized in that the pressure difference gauge is arranged so that the measuring position is inside the RSI and is mounted closer to the RSI than the first feed water pipe (12B) and the second feed water pipe (12A). rising parts (33). The nuclear power plant AZAAS according to any one of claims 5 to 7, characterized in that the pressure difference value for switching the injection line is set higher than the pressure difference with respect to the pressure difference between the feed water pipes (12A, 12B) during normal operation, as follows: that the injection line is not switched during normal operation. 9. The nuclear power plant AZAAS according to claim 8, characterized in that the pressure difference can be detected even assuming a pipe burst in the second feed water pipe (12A) close to the RSI, also closer to the RSI side than the second feed water pipe (12A). rising part (33A). The nuclear power plant AZAAS according to any one of claims 1 to 9, characterized in that the crack detector (29) has a timer configured to operate after the relaxation time after the crack has occurred, so that the crack detector (29) does not malfunction even with respect to the impact. a wave that may occur immediately after a rupture in the first feed water pipe (12B) or the second feed water pipe (12A). Nuclear power plant AZAAS according to any one of claims 1 to 10, characterized in that the pressure difference gauge has a "2 of 4" criterion to prevent erroneous measurements.