JP2003167088A - Boiling water nuclear power generating plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiling water nuclear power generating plant equipped with ECCS having minimum number of systems. <P>SOLUTION: The ECCS 81 is constructed by three divisions, that is, system A ECCS 82, system B ECCS 83 and system C ECCS 84. The driving power supply of dynamic devices such as a pump and motor-operated valve is supplied from system A power supply system 85, system B power supply system 86 and system C power supply system 87. The system A power supply system 85, the system B power supply system 86 and the system C power supply system 87 are mutually independent power supply systems. The system A ECCS 82 is provided with RHR one system which is low pressure system ECCS. The system B ECCS 83 is also provided with one train of RHR system which is low pressure system ECCS. These RHR systems are adapted to inject water into a reactor pressure vessel through a heat exchanger. The system C ECCS 84 is provided with one train of HPCF system which is high system ECCS. As described above, ECCS are only three trains in total. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention aims to reduce the amount of water that cools the core of the RPV by breaking the piping of the reactor pressure vessel (RPV) beyond the range of transient changes expected during normal operation. The present invention relates to a boiling water nuclear power plant equipped with an emergency core cooling system (ECCS) for injecting water into the RPV in an emergency to cool the core, and particularly to a boiling water nuclear power plant in which the ECCS has a function other than emergency water injection. It concerns power plants.

[0002]

2. Description of the Related Art The structure of an ECCS provided in a conventional boiling water nuclear power plant will be described.

FIG. 1 shows the configuration of a conventional 1.35 million KWe class improved boiling water nuclear power plant (hereinafter referred to as ABWR) ECCS. Further, FIG. 2 schematically shows the ECCS structure.

An outline of the nuclear power plant shown in FIG. 1 will be described.

A reactor pressure vessel (RPV) 9 having a fuel assembly in its core is housed so as to be entirely enclosed in a reactor containment vessel (PCV) 8. PC to store RPV9
The internal space of V8 is the dry well 19 and the pressure suppression chamber (S
/ C) 20. The dry well 19 is a space where the cooling water is discharged as a mixture of air and water in the event of a large loss of the cooling water in the RPV. The gas-water mixture discharged to the dry well 19 is introduced into a pressure suppression pool (S / P) 11 in the S / C 20 through a vent pipe (not shown), cooled and condensed, and the pressure in the PCV is increased. Suppress.

The condensate storage tank (CST) 10 placed outside the dry well 19 can also be placed inside the dry well 19.

The S / P 11 communicates with the RPV 9 through a pipe 42, a residual heat removal system (RHR system) pump 45, an RHR system heat exchanger 46, and a pipe 47. Also RPV9
Is the pipe 44, the pipe 42, the RHR system pump 45, the RHR
It has a flow path that returns to the RPV 9 through the system heat exchanger 46 and the pipe 47. These are each provided with three sections of power supply system (A, B, C), and constitute low voltage ECCS.

The reactor isolation cooling system (RCIC system) pump 30 driven by the turbine 24 injects water of CST 10 or S / P 11 into the RPV 9 through the pipes 26, 28 and 32. This belongs to the power supply system A. H
The PCF pump 13 is a CST 10 or S / P 11
Water is injected into the RPV 9 through the pipe 26, the pipe 15, the pipe 14, and the pipe 18. The HPCF system pump 13 is provided with two sections of a power supply system (B, C). The high pressure core water injection system (RCIC system) pump 30 and the HPCF system pump 13 constitute a high pressure ECCS.

The ABWR ECCS has been designed to satisfy the following conditions in order not only to function as an emergency water injection facility but also to have some regular functions. Has been done.

First, the driving power source for the dynamic equipment such as a pump is supplied from three independent power sources, and secondly, a high pressure and low flow rate operating point (medium or small rupture of the pipe connected to the RPV). Sometimes necessary operating conditions. At this time, the water level drops while the RPV remains at high pressure.) And operating point at low pressure and large flow rate (operating condition required when the pipe connected to the RPV is severely broken. At the same time as the pressure is rapidly reduced,
Because the water level inside the RPV drops rapidly. ) Is possible, and thirdly, R that can occur during normal operation
When transient water level drop in PV occurs, it is possible to operate at high pressure and low flow rate operating point to implement make-up water into the RPV; fourth, it is possible to remove residual heat generated in the reactor when the reactor is shut down; Fifth, it is possible to cool the inside of the PCV in the event of an accident.

Conventional ECCS to meet the above requirements
Will be described with reference to FIG.

ECCS1 is A system ECCS2 and B system ECC
It is composed of three sections, S3 and C-system ECCS4. Power system for A system 5, power system for B system 6, power system for C system 7
Is supplied with driving power for dynamic equipment such as the pumps 13, 30, 45 and motor-operated valves shown in FIG. The A system power supply system 5,
The B system power supply system 6 and the C system power supply system 7 are independent power supply systems.

Each of the three sections has a total of two systems, one for the high-voltage system ECCS and one for the low-voltage system ECCS.
The A-system ECCS 2 includes a high pressure system ECCS, a reactor isolation cooling system (RCIC system), and a low pressure system ECCS, a residual heat removal system (RHR system). The B-system ECCS 3 includes one high-pressure core injection system (HPCF system) as a high-pressure ECCS and RHR as a low-pressure ECCS.
It has one system. The C system ECCS4 is also a HPCF system 1 system as a high voltage system ECCS, a low voltage system ECCS.
Is equipped with one RHR system.

FIG. 3 shows the relationship between the pump performance of the high pressure system ECCS and the low pressure system ECCS. FIG. 3 shows the pump flow rate on the horizontal axis and the pump head on the vertical axis. The operating point of the ECCS pump required when the pipe connected to the RPV is broken is small and small, and the operating point of the ECCS pump that is required when the pipe is large broken is the operating point 72. That is, the ECCS may be composed of a pump having a performance curve that passes through these two points. However, both of the two operating points are 1
A pump having a performance curve that can be covered with a table is difficult to manufacture and is disadvantageous in terms of cost.
It is designed to have two series of CCS pumps (pumps having performance curve 73) and low pressure ECCS pumps (pumps having performance curve 74) in each section. Since the division must be divided into 3 divisions like the power source configuration, the conventional technology had a total of 6 series of ECCS in the boiling water nuclear power plant.

[0015]

In the prior art, a boiling water nuclear power plant has a total of six systems as ECCS in order to satisfy the four requirements shown in the prior art. However, ECCS is not only a system that is basically not used during normal operation, but also a system that has a high equipment cost because it requires a high safety grade. Therefore, installing multiple systems of ECCS in one plant is an economically disadvantageous factor.

In view of the above problems, the present invention provides an EC
The object is to improve the economical efficiency of a nuclear power plant by making the number of CS systems as simple as possible.

[0017]

DISCLOSURE OF THE INVENTION According to the present invention, a pipe which is in communication with an RPV and which circulates a fluid such as water is broken to break the RPV.
In an emergency, where the amount of water that cools the core in the reactor decreases beyond the range of transient changes expected during normal operation, the RPV
Emergency core cooling system (E
In a boiling water nuclear power plant equipped with CCS),
The ECCS has three systems each including one pump for pouring water into the RPV, and the drive power source of each pump is a separate power source system of three independent sections, and at least two of the three systems have at least two systems. A heat exchanger for cooling the cooling water poured into the RPV is provided.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings showing examples of the present invention. Embodiments of the present invention are shown in FIGS. 4, 5, 12, and 13, and the present invention will be described in comparison with a conventional example in important points.

FIG. 4 shows an embodiment of the present invention 700,000 Kwe
ECC of a class improved boiling water nuclear power plant (about half the electric output of the improved boiling water nuclear power plant shown in the prior art)
The structure of S is shown.

FIG. 5 shows an ECC according to an embodiment of the present invention.
2 schematically shows the configuration of S. Like the conventional technology, ECCS81 is A system ECCS82 and B system ECCS8.
3 and C system ECCS 84.

Each of the A-system power supply system 85 and the B-system power supply system 8
6, C-system power supply system 87 supplies drive power for dynamic equipment such as pumps and motor-operated valves. The A system power supply system 85, the B system power supply system 86, and the C system power supply system 87 are independent power supply systems. The A-system ECCS 82 includes one RHR system, which is a low-voltage ECCS. The B-system ECCS 83 also includes one RHR system that is a low-voltage ECCS. The C-type ECCS 84 is a high-voltage ECCS H
It has one PCF system. Therefore, ECCS is only 3 systems in total.

Here, in order to deepen the understanding of the present invention, the conventional examples shown in FIGS. 6, 7, 8, 9, 10 and 11 will be touched.

FIG. 6 shows the system configuration of the HPCF system. Condensate storage tank (CST) 10 or pressure suppression pool (S
/ P) 11 through the pipe 12 or the pipe 15 respectively (this switching is performed by opening and closing the motor-operated valve 16 and the motor-operated valve 17) to the HPCF system pump 13, and after boosting the pressure with the pump 13, the pipe 14 and the pipe 18 Through RP
Inject into V.

FIG. 7 shows the system configuration of the RCIC system. RP
The steam generated in V9 is passed through a pipe 22 and a pipe 23 branching from the main steam pipe 21, and an RCIC pump 30
It is guided to the turbine 24 which is directly connected to the shaft and drives this. Exhaust gas from the turbine 24 is discharged to the S / P 11 through a pipe 25. The RCIC system pump 30
Is a CST10 or S / P similar to the HPCF system.
The water of 11 is used as a water source through the pipe 26 and the pipe 28 (this switching is performed by opening and closing the motor-operated valve 27 and the motor-operated valve 29), and the pressure of the water is increased to form the pipes 31 and 32.
To the RPV 9 through. The HPCF system pump 13 and the RCIC system pump 30, which are high pressure system ECCS, are high-degree pumps that can inject water into the RPV even near the normal operating pressure of the plant.

FIG. 8 shows the RHR system and ADS during RPV water injection.
The system configuration of is shown. The water of the S / P 11 is guided to the RHR system pump 45 through the pipe 42, and the RHR system pump 4
The pressure is increased at 5 and injected into the RPV 9 through the pipe 47. The RHR system pump 45 is a low pressure system ECCS and is RPV 9
Since the pump is a low-degree pump which is assumed to inject water into the RPV 9 when the internal pressure is near atmospheric pressure, water cannot be injected when the pressure inside the RPV 9 is high. In such a case, the pressure inside the RPV 9 is lowered by the ADS 49 before the RHR system pump 45 is started. ADS is the RP
The main steam relief safety valve 49 installed in the main steam pipe 21 that guides the steam generated in V9 to the turbine side is forcibly opened by an accumulator, and the steam is discharged from the pipe 48 into the S / P 11 through the pipe 50. It is a system that does.

The activation logic of the ADS is shown in FIG. "R
Condition 6 "The water level in PV9 has dropped below the specified value."
5 and the condition 66 that "the pressure in the dry well 19 has become higher than the specified value" are satisfied, and the condition 68 that "the low pressure system ECCS is activated" is satisfied, "ADS49 activation" The operation 67 is executed.

FIG. 10 shows the system configuration of the RHR system in the shutdown reactor residual heat removal operation mode. FIG. 10 shows a state in which the electric valve 41 is closed and the electric valve 43 is opened from FIG. The water in the RPV 9 is passed from the pipe 44 through the pipe 42 to the R
It is led to the HR system pump 45, the pressure is raised by the RHR system pump 45, the RHR system heat exchanger 46 is passed through to cool it, and the pipe 47 is returned to the RPV 9. Cooling water is supplied to the RHR heat exchanger 46 through a pipe 61 and is discharged through a pipe 62.

FIG. 11 shows the system configuration of the RHR system in the containment cooling operation mode during an accident. In FIG. 11, the motor-operated valve 67 and the motor-operated valve 68 are closed from FIG.
Is a state in which the electric valve 65 and the electric valve 66 are opened. S
/ P of water is led to the RHR system pump 45 through the pipe 42, the pressure of which is increased by the RHR system pump 45, and then through the pipe 69 and the pipe 70 from the sparger 101 and the sparger 102, respectively, to the dry well 105 and the S / C 20.
To water.

FIG. 12 shows the relationship between the pump performances of the high pressure ECCS and the low pressure ECCS. FIG. 12 shows the pump flow rate on the horizontal axis and the pump head on the vertical axis. The operating point of the ECCS pump required for a small or medium rupture of the piping connected to the RPV is the operating point 91, and the ECC required for a large rupture.
The operating point of the S pump is the operating point 92. By reducing the plant output to 100 MWe or less, it is possible to reduce the required flow rate of the low pressure system ECCS and allow the performance curve 93 of the HPCF system pump to pass through these two points. As a result, the C-system ECCS does not require the low-voltage ECCS, and it is possible to configure only one HPCF system.

On the other hand, the A system ECCS and the B system ECCS strengthen the ADS starting condition, and the high pressure system ECCS can be deleted by setting the starting pressure of the low pressure system ECCS higher than that of the conventional technique. Only a certain RHR system was used. FIG. 13 shows the enhancement of the ADS start condition. FIG. 13 is a diagram showing the ADS activation logic similarly to FIG. That is, in the present invention, the condition 65 "the water level in the RPV 9 has dropped below the specified value" and the condition 6 "the pressure in the dry well 19 has risen above the specified value".
When either one of 6 is satisfied and the condition 68 that “low-voltage system ECCS is activated” is satisfied, “AD
The operation 67 "Start S49" is executed.

Since the starting condition of the ADS 49 is relaxed in this way, even when the internal pressure of the RPV 9 is high, the starting of the ADS and the PR by the RHR system (low pressure system ECCS) are performed.
Water injection into V can be performed more reliably. Furthermore,
The set value of the RPV internal pressure at the time of starting the low pressure system ECCS was increased.

This is because, unlike the HPCF system which can start the pump immediately after detecting the drop in the water level in the RPV 9 and start the water injection into the RPV 9, the RHR system is the RPV system.
Since the ADS 49 is activated after detecting the decrease in the water level inside the RPV 9 and the pressure inside the RPV 9 is lowered until it reaches the operable pressure of the RHR system, the APV is activated and water is injected into the RPV 9. This is because it takes some time to start. Therefore, the R for starting the RHR system
By increasing the pressure setting value in the PV, the time difference until the start of water injection is shortened, and high pressure system ECC such as HPCF system
The need to install S has been reduced.

As described above, according to the present invention, one of the high-voltage ECCS or the low-voltage ECCS is assigned to each of the three ECCS sections.
Provide a boiling water nuclear power plant equipped with ECCS that is installed only in each system.

The main features of the present invention described above are as follows.

The first feature is that the ECCS is configured to have a total of three systems, one system for each power source section, and two or more systems among them can inject water from the pump to the RPV through the heat exchanger. .

As a result, an ECCS having the number of systems reduced to the same number as the number of power supply divisions, and an ECCS having a function of removing decay heat generated in the core at the time of reactor shutdown and a function of cooling the containment vessel at the time of accident It is possible to provide the equipped boiling water nuclear power plant.

The second feature is that the structure of ECCS is high pressure system E.
The CCS has one system and the low-pressure system ECCS has two systems, that is, three systems in total, and "the water level in the RPV is lower than a specified value" or "the pressure in the dry well in the PCV is higher than the specified value". That is, one of the above conditions is satisfied, and that "the low-voltage system ECCS is activated" is satisfied as the activation condition of the ADS.

As a result, the high-voltage ECCS and the low-voltage EC
It is possible to provide the ECCS configuration that realizes the first means by CS and has a function of injecting makeup water into the RPV when the water level in the RPV transiently drops during normal operation.

The third characteristic is the ECC described in the first characteristic.
In the S configuration, the starting pressure of the low pressure system ECCS is set to be higher than half the starting pressure of the high pressure system ECCS and smaller than the normal operating pressure of about 7 MPa (gage).

Thus, in addition to the function of the second feature, in the event of an accident such as breakage of the pipe connected to the RPV, the low pressure ECCS starts water injection into the RPV as quickly as the high pressure ECCS. ECCS capable
To provide a boiling water nuclear power plant.

The fourth feature is that the electric power output of the power plant is set to 1,000,000 KWe or less in the ECCS configuration described in the first feature or the second feature.

This makes it possible to provide a boiling water nuclear power plant having an appropriate plant output level that realizes the first or second characteristic.

[0043]

According to the present invention, the economical efficiency of a nuclear power plant can be improved with a simple structure.

[Brief description of drawings]

FIG. 1 is a schematic diagram related to a conventional example and generally showing a piping system of RPV and ECCS.

FIG. 2 is a schematic diagram relating to a conventional example and summarizing ECCS in relation to a power supply system.

FIG. 3 is a performance curve diagram of an ECCS pump according to a conventional example.

FIG. 4 is a schematic view showing an entire RPV and ECCS piping system in an example according to an embodiment of the present invention.

FIG. 5 is a schematic diagram in which ECCS is summarized in relation to a power supply system in an example according to the embodiment of the present invention.

FIG. 6 is a diagram related to a conventional example and showing a system configuration of an HPCF system.

FIG. 7 is a diagram related to a conventional example and showing a system configuration of an RCIC system.

FIG. 8 is a diagram related to a conventional example and showing a system configuration in an RHR system RPV water injection mode.

FIG. 9 is a block diagram showing a starting principle of an ADS system according to a conventional example.

FIG. 10 is a diagram related to a conventional example and showing a system configuration in a cooling mode during stop of an RHR system.

FIG. 11 is a diagram relating to a conventional example and showing a system configuration in an RHR system containment vessel cooling mode.

FIG. 12 shows an example of ECCS according to an embodiment of the present invention.
It is a performance curve figure of a pump.

FIG. 13 is a block diagram showing the starting principle of the ADS system in the example according to the embodiment of the present invention.

[Explanation of symbols]

1,81 ... ECCS, 2,82 ... A ECCS, 3,8
3 ... B system ECCS, 4, 84 ... C system ECCS, 8 ... Reactor containment vessel, 9 ... Reactor pressure vessel (RPV), 10 ... Condensate storage tank, 11 ... Suppression pool (S /
P), 13 ... High pressure core water injection system (HPCF system) pump, 1
9 ... Dry well, 20 ... Pressure suppression chamber (S / C), 21
… Main steam piping, 24… Cooling system for reactor isolation (RCIC
System) turbine, 30 ... RCIC system pump, 45 ... residual heat removal system (RHR system) pump, 46 ... RHR system heat exchanger,
49 ... Automatic decompression system (ADS), 73, 93 ... High pressure system EC
CS pump performance curve, 74, 94 ... Low pressure system ECCS pump performance curve, 101 ... Drywell sparger, 102
... S / C sparger.

Continued front page    (72) Inventor Masayoshi Matsuura             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Nuclear Business Division

Claims (5)

[Claims] Claim: What is claimed is: 1. A reactor pressure vessel (RPV) having a fuel assembly in a core, and a RPV that entirely encloses the RPV and prevents the radioactive substance from leaking to the outside even if the radioactive substance is released from the RPV. A reactor containment vessel (PCV) having a function as an airtight container for sealing, a condensate storage tank, a pressure suppression pool, the RPV, the condensate storage tank, and the pressure suppression pool, and water, etc. Of the fluid, and an automatic depressurization system (ADS) that operates so as to reduce the pressure in the RPV in an emergency, and the pipe breaks to cool the core in the RPV so that the amount of water is normal. In a boiling water nuclear power plant equipped with an emergency core cooling system (ECCS) that cools the core by injecting water into the RPV in an emergency in which the transient change is expected to decrease beyond the range. Stomach, the ECCS is, husband the pump for water injection to the RPV 's 1
It has three systems with each one, and the driving power source of each pump is a separate power source system of three independent sections.
A boiling water nuclear power plant, which is equipped with a heat exchanger for cooling the cooling water poured into V. 2. The ECCS according to claim 1, wherein the ECCS has one system as a high pressure system and the other two systems as a low pressure system, a high pressure system having a high pressure pump and a low pressure system having a low pressure system. A boiling water nuclear power plant characterized by using a specified pump. 3. The method according to claim 2, wherein the high pressure system ECCS injects water into the RPV.
The pressure in V is the pressure during normal operation [about 7 MPa (gag
e)] is almost the same, and the injection of water into the RPV by the ECCS of the low pressure system is performed by RP.
The pressure within V can be set to 1/2 or less of that during normal operation, and the condition for the ADS to operate is that "the water level in the RPV is lower than a specified value" or "in the PCV storing the RPV (dry well B) is higher than a specified value "and" the low-pressure system ECCS is activated ", the boiling water nuclear power plant. 4. The high pressure system EC according to claim 2, wherein the pressure at which the low pressure system ECCS starts is the high pressure system EC.
A boiling water nuclear power plant, which has a value that is greater than half the pressure at which CS starts and lower than the pressure during normal operation. 5. The boiling water nuclear power plant according to any one of claims 1 to 4, wherein the power output of the power plant is 1,000,000 KWe or less.