JPH08313686A - Emergency core cooling system of boiling water reactor - Google Patents

Abstract

PURPOSE: To reduce power capacity necessary in emergency and improve reliability by using isolation condenser, diesel driven high pressure injection system and reactor isolation cooling system in combination for high pressure system. CONSTITUTION: Train I has an isolation condenser (IC) 5/passive containment cooling system (PCSS) 6, a residual heat removal, system (low pressure system) (LPFL/RHR) 3 and an emergency gas turbine generator (GT) 8. Train II has a diesel driven injection system (high pressure system) (HDIS) 7, LPFL/RHR 3 and GT 8. Train III has an advanced reactor isolation cooling system (ARCIC) 9, LPFL/RHR 3 and GT 8. During reactor isolation, water level in reactor pressure vessel is maintained by three kinds of high pressure systems, IC 5, HDIS 1 and ARCIC 9. As these three systems do not depend on external alternating power source, load demand to emergency generator is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emergency core cooling system for a boiling water reactor installed as a safety system for a nuclear reactor.

[0002]

2. Description of the Related Art As shown in FIG. 5, an emergency core cooling system (ECCS) of a boiling water reactor, in which a conventional reactor functions at a high pressure, is shown in FIG.
C) 1-Residual heat removal system (low pressure system) (LPFL / RHR)
3-Class I equipped with a large emergency diesel generator (emergency DG) 4 and high pressure core water injection system (high pressure system) (HPC
F) 2 and residual heat removal system (low pressure system) (LPFL / RH
R) 3 and a large emergency diesel generator (emergency DG)
Category II equipped with and Category III of the same system as this Category II
It consists of

In recent boiling water type light water reactors in which the safety system is divided into three sections, a high pressure water injection system is installed so that the reactor core can be cooled in a high pressure state of the reactor.
Particularly, in the improved boiling water type light water reactor, two electric pumps for the high pressure core water injection system are installed in order to enhance the water injection capacity at high pressure.

[0004]

Since this electric pump requires a large lift, the electric motor also needs to have a large output of about 1500 KW. Therefore, in an emergency, the electric pump must be powered. The load on the diesel generator 4 was large.

Further, since the high-pressure water injection system in the boiling water type light water reactor requires injection within 30 to 36 seconds after reaching the starting water level, the rise time required for the emergency diesel generator 4 is short and strict. It was a thing. For this reason, the emergency diesel generator 4 has a large size and is installed so as to start quickly and enter a steady state.

In the improved boiling water type light water reactor, the high pressure water injection system 2 has the same system as described above in the sections II and III.
Since it is installed in 2 divisions, it is necessary to take measures when a common cause failure is considered.

In the conventional example, since a high-pressure electric pump is installed, a large power source capacity is required, and the power source is required to be quickly supplied in an emergency. Therefore, the emergency diesel generator prepared for this purpose has a large structure, and requires cooling water for auxiliary machinery, and it has a problem of low economic efficiency.

The present invention has been made to solve the above problems, and reduces the power supply capacity required in an emergency, prolongs the startup time of the emergency core cooling system (ECCS), and is a plant resistant to common factor failures. Another object of the present invention is to provide a highly reliable emergency core cooling system for a boiling water reactor, which allows a time margin before starting.

[0009]

A first aspect of the present invention relates to an emergency core cooling system in which a nuclear reactor functions at a high pressure, wherein an isolation condenser-residual heat removal system (low pressure system) -emergency gas turbine generator is provided. Equipped Category I, diesel driven water injection system (high pressure system) -Residual heat removal system (low pressure system) -Equipped with emergency gas turbine generator Category II, improved reactor isolation cooling system (high pressure system)- Residual heat removal system (low pressure system)-
It is characterized by comprising Category III equipped with an emergency gas turbine generator.

A second aspect of the invention is a cooling system for reactor isolation (high pressure system) -residual heat removal system (low pressure system) -Section I equipped with a small diesel generator, and diesel driven water injection system (high pressure system)
-Residual heat removal system (low pressure system) -Section II equipped with a small diesel generator and reactor isolation cooling system (high pressure system) -Residual heat removal system (low pressure system) -Section III equipped with a small diesel generator It consists of and.

A third aspect of the present invention is a reactor heat removal water level control system-a shroud water injection residual heat removal system-a category I equipped with an emergency gas turbine generator, a diesel driven high pressure water injection system (high pressure system), and a shroud water injection. Residual heat removal system-Category II equipped with emergency gas turbine generator, Reactor isolation cooling system-Shroud water injection residual heat removal system-Class III equipped with emergency gas turbine generator And

A fourth invention is a high pressure core water injection system-residual heat removal system-Section I equipped with an emergency gas turbine generator, a diesel driven high pressure water injection system (high pressure system) -residual heat removal system-emergency gas turbine. It is characterized by being composed of a category II equipped with a generator and a category III equipped with a reactor isolation cooling system-residual heat removal system-emergency gas turbine generator.

[0013]

In the present invention, in order to eliminate the electric pump which is required to operate at high pressure, in the first invention, an isolation capacitor (IC), a diesel driven high pressure water injection system (HD
IS) and Advanced Reactor Isolation Cooling System (ARCIC)
Are used in combination for a high pressure system.

In addition, a static containment cooling system (PCC)
S) is adopted and the residual heat removal system (LPFL / RHR) has a backup function for heat removal from the containment vessel in the event of an accident, thereby enhancing the ability to respond to severe accidents. As an emergency power generator, an emergency gas turbine generator is used instead of a large capacity diesel generator.

Of the systems constituting the emergency core cooling system, whichever system is used when a system that functions at high pressure is combined with an isolation condenser, a diesel driven high pressure water injection system and an improved reactor isolation cooling system. However, since an AC power source from the outside is not required, the emergency electric load of each of the sections I, II and III is reduced.

In the method of combining the above three types as a high pressure system, a part of the first invention is replaced as in the second invention to provide the improved reactor isolation cooling system in two sections. It is also possible.

Instead of the current emergency diesel generator, which requires a large space as equipment and cooling water,
By adopting a gas turbine generator with a small frame, the load on the auxiliary cooling water system will be reduced, improving economic efficiency and improving reliability.

By adopting both the first invention and the second invention at the same time, since the high-voltage system requiring quick injection does not require a power source from the emergency generator, It will be possible to employ a gas turbine generator that has a margin of start-up time and is slower in start-up time but superior in reliability and economy to diesel generators without major technological development.

Since the electrical load in an emergency is reduced,
Even if a diesel generator is used as an emergency generator, the installed capacity can be reduced. Further, the number of systems required to operate the high-voltage system is reduced, and the facility capacity of the ECCS system as a whole can be reduced.

Regarding the reliability of the safety network, PSA (probabilistic safety evaluation) is almost the same because the conventional three-section independent structure (for example, HDIS, ARCIC, IC) is used as heat removal means at high pressure. Have the credibility of.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an emergency core cooling system of a boiling water reactor according to the present invention will be described with reference to FIG. In FIG. 1, Category I is an isolation capacitor (IC) 5 /
It is provided with a static containment vessel cooling system (PCCS) 6, a residual heat removal system (low pressure system) (LPFL / RHR), and an emergency gas turbine / generator (GT) 8. Category II includes a diesel driven water injection system (high pressure system) (HDIS) 7, a residual heat removal system (low pressure system) (LPFL / RHR) 3, and an emergency gas turbine generator (GT) 8. Category III is the advanced reactor isolation cooling system (high pressure system) (ARCIC) 9
And a residual heat removal system (low pressure system) (LPFL / RHR) 3 and an emergency gas turbine generator 8.

The isolation capacitor (IC) 5 is composed of a pool storing water for removing decay heat and a heat exchanger, and the reactor is operated at a high pressure only by driving a motor-operated valve with a DC power source supplied from a battery. It is a system that removes heat by condensing steam in a state.

The diesel driven water injection system (high pressure system) 7 is a high pressure water injection system directly connected to the diesel engine and is a highly independent water injection system that does not depend on the emergency power source and does not require an auxiliary cooling water system. The improved reactor isolation cooling system (high pressure system) 7 is a reactor isolation cooling (ARCIC) system equipped with a turbine driven by reactor steam and a small generator, and uses electricity generated by the generator as a battery power source. By using it for charging, it is possible to extend the drive time when all AC power is lost.

The residual heat removing system (low pressure system) 3 is also used in the conventional improved boiling water reactor, and has both a low pressure water injection function and a containment vessel cooling function. The static containment cooling system 6 is a system in which the pool as a heat sink is shared with the isolation condenser 5 to remove heat from the atmosphere inside the containment vessel without the operation of dynamic equipment, and should a severe accident occur, Moreover, it has the function of maintaining the integrity of the containment vessel without the dynamic operation of the equipment.

Next, the operation of the first embodiment will be described. At the time of reactor isolation, the water level in the reactor pressure vessel is maintained by three types of high-pressure systems having isolation capacitor 5, diesel-driven high-pressure water injection system 7 and improved reactor isolation cooling system 9. Since these three systems do not depend on the external AC power supply, they are expected to operate even when all AC power is lost.

When various pipes are broken, the maintenance of the reactor water level at high pressure is achieved by a system having two types of high-pressure water injection functions, particularly a diesel-driven high-pressure water injection system 7 and an improved reactor isolation cooling system 9. It is possible to maintain the reactor water level together with the operation of the automatic depressurization system, which is the depressurization system of the reactor.

Even if the above two high pressure systems are not operated, the residual heat is reduced at a low pressure after the reactor pressure is sufficiently reduced by raising the injection pressure of the low pressure system of one section to some extent. The water level of the reactor is maintained by the low pressure water injection mode, which is one of the functions of the removal system 3.

The heat removal of the atmosphere in the containment vessel is achieved by the static containment vessel cooling system 6 sharing the heat sink with the isolation condenser 5 without expecting the operation of the dynamic equipment, and the residual heat removal system 3 By having the backup function for the containment vessel cooling mode, it has sufficient ability to cope with severe accidents.

Next, the effect of the first embodiment will be described. In this embodiment, by arranging a system that does not require an external AC power supply as a system used at high voltage, it is possible to enhance the resistance against the loss of all AC power supply and remove the electric pump that requires a large power supply capacity. As a result, it is possible to reduce the load demand on the emergency generator.

As described above, by removing the electric pump from the high pressure system, the emergency electric load for each section is reduced, and for a short time after the start signal is generated in response to transient change circumstances such as loss of all water supply. Since the high-voltage system that had to start injection at the load deviated from the load of the emergency AC power supply, the specifications for the emergency power supply were eased, and the options for an emergency power generator expanded, resulting in compact diesel power generation. It is possible to adopt a gas turbine generator that has excellent reliability and economic efficiency, although it has a slow start-up time. In addition, the reliability of the safety system in consideration of common factor failures is improved by making the system that functions at high voltage different for each category.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, Category I is an improved reactor isolation cooling system (high pressure system) (ARCIC) 9, a residual heat removal system (low pressure system) (LPFL / RHR) 3, and a small diesel generator (DG). ) 10 are provided. Category II includes a diesel driven water injection system (high pressure system) (HDIS) 7, a residual heat removal system (low pressure system) (LPFL / RHR) 3, and a small diesel generator (DG) 10. Also, Category II
I has the same system as Category I.

Next, the operation of the second embodiment will be described. When the reactor is isolated, the water level in the reactor pressure vessel is maintained by the two types of three high-pressure systems having the diversity of the diesel-driven high-pressure water injection system 7 and the improved reactor isolation cooling system 9. Since these three systems do not depend on the external AC power supply, they are expected to operate even when all AC power is lost.

When various pipes are broken, the maintenance of the reactor water level at high pressure is achieved by the system having two types of high-pressure water injection functions, particularly the diesel-driven high-pressure water injection system 7 and the improved reactor isolation cooling system 9.

At a low pressure after the reactor pressure has been sufficiently reduced, the water level of the reactor is maintained by the low pressure water injection mode which is one of the functions of the residual heat removal system 3. The heat of the atmosphere in the containment vessel can be removed in the containment vessel cooling mode of the residual heat removal system 3.

Next, the effect of the second embodiment will be described. In the second embodiment, as in the first embodiment, a system that does not require an external AC power source is arranged as a system used at high voltage, thereby increasing the resistance against the loss of all AC power sources and increasing the power supply. By removing the electric pump that requires capacity, the load demand on the emergency generator is reduced.

As described above, by removing the electric pump from the high pressure system, the emergency electric load for each section is reduced, and it is necessary to start the injection in a short time after the activation signal is generated. Since the load is off the load, the choice as an emergency generator is expanded, and it is possible to use a small diesel generator 10 or a gas turbine generator that has a slow startup time but excellent reliability and economy. become.

Although the variety of systems that function at high pressure is reduced compared to the first embodiment, one system can be added as a water injection system at high pressure to improve the reliability of the water injection function. .

Next, a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, a section I isolation capacitor (IC) 5 / of the first embodiment is used.
The reactor heat removal water level control system (RHVLC) 11 is adopted instead of the static containment vessel cooling system (PCCS) 6, and the low pressure of the residual heat removal system (low pressure system) (LPFL / RHR) 3 of the first embodiment is adopted. The injection destination in the injection mode is changed from outside the shroud to inside the shroud, the residual water heat removal system (LPLI / RHR) 12. Incidentally, since the division II and the division III are the same as those in the first embodiment, the description thereof will be omitted.

Diesel driven high pressure water injection system 7, improved reactor isolation cooling system 9 and RHVLC 11 during reactor isolation
The water level in the reactor pressure vessel is maintained by the three types of high-pressure systems with diversity. Since these three systems do not depend on the external AC power supply, they are expected to operate even when all AC power is lost.

When various pipes are broken, diesel driven high pressure water injection system 7, improved reactor isolation cooling system 9 and RHVL
Maintaining the reactor water level at high pressure is achieved by a system with three types of high-pressure water injection functions, C11.

At a low pressure after the reactor pressure is sufficiently reduced, the low water injection mode, which is one of the functions of the residual heat removal system 12, maintains the water level of the reactor by the cooling water injected into the shroud. It The heat of the atmosphere in the storage container can be removed in the storage container cooling mode of the residual heat removal system 12.

Next, the effect of the third embodiment will be described. In the third embodiment, similarly to the first embodiment, a system that does not require an external AC power source is arranged as a system that is used at high voltage, thereby increasing the resistance against the loss of all AC power sources and increasing the power supply capacity. By removing the electric pump that requires the, the load demand on the emergency generator is reduced.

As described above, by removing the electric pump from the high pressure system, the emergency electric load for each section is reduced, and it is necessary to start the injection in a short time after the start signal is generated. Since the load deviates from the load, choices as an emergency generator are expanded, and it is possible to adopt a small diesel generator or a gas turbine generator with a slow start-up time but excellent reliability and economy. Become.

Although the variety of systems that function at high pressure is reduced as compared with the first embodiment, one system can be added as a water injection system at high pressure to improve the reliability of the water injection function. .

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 shows a fourth embodiment of the present invention. In the fourth embodiment, instead of the isolation condenser (IC) 5 / static containment vessel cooling system (PCCS) 6 of the first embodiment, the same high pressure core water injection system 13 as the conventional ABWR is adopted. is there. Other, Category II and Category
Since III is similar to that of the first embodiment, its explanation is omitted.

Diesel driven high pressure water injection system 7 during reactor isolation, improved reactor isolation cooling system and high pressure core water injection system
The water level in the pressure vessel is maintained by three types of high pressure systems with 13 varieties. Since the two systems other than the high pressure core water injection system 13 do not depend on the external AC power supply, they are expected to operate even when all AC power is lost.

When various pipes are broken, the reactor water level can be maintained at high pressure by a system having three types of high-pressure water injection functions: diesel-driven high-pressure water injection system 7, improved reactor isolation cooling system 4 and high-pressure core water injection system 13. To be achieved.

At low pressure after the reactor pressure has been sufficiently reduced, the water level of the reactor is maintained by the cooling water injected into the shroud by the low pressure water injection mode which is one of the functions of the residual heat removal system 3. It The heat of the atmosphere in the containment vessel can be removed in the containment vessel cooling mode of the residual heat removal system 3.

In the fourth embodiment, by arranging a system that does not require an external AC power supply in two sections of the safety system as a system used at high voltage, the resistance against the loss of all AC power supply is increased and the By removing the electric pump that requires power supply capacity, it is possible to reduce the load demand on the emergency generator.

As described above, by removing the electric pump from the high pressure system, the emergency electric load of the two sections is reduced, and the high pressure system that needs to start the injection in a short time after the start signal is generated is Since the load deviates from the two categories, the choice as an emergency generator expands, and it is possible to adopt a small diesel generator or a gas turbine generator that has a slow startup time but excellent reliability and economy. It will be possible. In addition, it is possible to ensure the diversity of the system that functions at high voltage and also ensure the reliability by providing the emergency generator with the variety.

[0051]

According to the present invention, by reducing the load demand on the generator as a power source in an emergency and delaying the start time of load generation, a small emergency diesel generator is adopted, Also, the impact on the accessory cooling system can be reduced.

Further, in the present invention, by reducing the load demand on the generator as an emergency power source and delaying the load generation start time, a gas turbine generator is adopted as an alternative and the impact on the building is improved. To reduce the load on the auxiliary system cooling water system and improve reliability.

Further, in the present invention, since the high-voltage system has an independent three-section structure without using the emergency generator except for the fourth embodiment, the reliability as a safety network equivalent to the conventional one is maintained. It is possible to increase the resistance to the loss of all AC power sources and reduce the cost as a whole.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration in a first embodiment of an emergency core cooling system of a boiling water reactor according to the present invention.

FIG. 2 is a sectional view showing a schematic configuration in a second embodiment of an emergency core cooling system of a boiling water reactor according to the present invention.

FIG. 3 is a sectional view showing a schematic configuration in a third embodiment of an emergency core cooling system of a boiling water reactor according to the present invention.

FIG. 4 is a sectional view showing a schematic configuration in a fourth embodiment of an emergency core cooling system of a boiling water reactor according to the present invention.

FIG. 5 is a sectional view showing a schematic configuration of an emergency core cooling system of a conventional boiling water reactor.

[Explanation of symbols]

1 ... Cooling system during reactor isolation (high pressure system), 2 ... High pressure core water injection system (high pressure system), 3 ... Residual heat removal system, 4 ... Large emergency diesel generator, 5 ... Isolation condenser, 6 ...
Static containment vessel cooling system (SA compatible), 7 ... Diesel driven high pressure water injection system (high pressure system), 8 ... Emergency gas turbine generator, 9 ... Improved reactor isolation cooling system, 10 ... Small emergency diesel power generation Machine, 11 ... Reactor heat removal water level control system (RHV
LC), 12 ... Shroud water injection residual heat removal system, 13 ... High pressure core water injection system.

Claims (6)

[Claims] 1. An isolation condenser-residual heat removal system (low pressure system) -Section I equipped with an emergency gas turbine generator, diesel driven water injection system (high pressure system) -residual heat removal system (low pressure system) -emergency It is composed of Category II equipped with an emergency gas turbine generator and Category III equipped with a reactor isolation cooling system (high pressure system) -residual heat removal system (low pressure system) -emergency gas turbine generator. The emergency core cooling system for boiling water reactors. 2. A reactor isolation cooling system (high pressure system) -residual heat removal system (low pressure system) -Section I equipped with a small diesel generator, and a diesel driven water injection system (high pressure system) -residual heat removal system ( Low-voltage system) -Category II equipped with a small diesel generator
And a cooling system during reactor isolation (high pressure system) -residual heat removal system (low pressure system) -Section III equipped with a small diesel generator, an emergency core of a boiling water reactor Cooling system. 3. A reactor heat removal water level control system-a shroud water injection residual heat removal system-a category I equipped with an emergency gas turbine generator, a diesel driven high pressure water injection system (high pressure system) -a shroud water injection residual heat removal System-Category II equipped with an emergency gas turbine generator, and Reactor isolation cooling system-Shroud water injection residual heat removal system-Category III equipped with an emergency gas turbine generator Emergency core cooling system for boiling water reactors. 4. A high pressure core water injection system-residual heat removal system-Class I equipped with an emergency gas turbine generator, and a diesel driven high pressure water injection system (high pressure system) -residual heat removal system-emergency gas turbine generator. An emergency core cooling system for a boiling water reactor characterized in that it comprises a division II provided and a division III equipped with a reactor isolation cooling system-residual heat removal system-emergency gas turbine generator . 5. The combination of the diesel driven high pressure water injection system (high pressure system), the reactor isolation cooling system, the isolation condenser, or the reactor heat removal water level system. Emergency Cooling System for Boiling Water Reactor. 6. Use of the small emergency diesel generator in place of the emergency gas turbine generator, or use of the emergency gas turbine generator in place of the small emergency diesel generator. Claim 1 characterized by
An emergency core cooling system for a boiling water reactor according to any one of claims 1 to 4.