JPH03216592A - Cooling water supplying device of boiling water nuclear reactor - Google Patents

Abstract

PURPOSE:To improve safety by opening an open/close valve, when a cooling water supply from a high pressure core cooling system into a nuclear reactor pressure vessel is not conducted even though the water level of the nuclear reactor lowers below a specific level by which the high pressure core cooling system should be actuated. CONSTITUTION:A flow meter 8 of a high pressure core cooling system, a water level meter 2 of a nuclear reactor and an open/close valve 13 are electrically connected to a control device 13 of the open/close valve. The control device 13 of the open/close valve feeds a flow rate signal S1 from a flow meter 8 of the high pressure core cooling system, and a water level signal S2 from the water level meter 2 of the nuclear reactor, and thereafter, in case that it is confirmed that no cooling water is supplied into a nuclear reactor vessel from the high pressure core cooling system even though the water level of the nuclear reactor lowers below a specific level by which the high pressure core cooling system should be actuated, the open/close valve 12 is controlled to be opened. Accordingly, even if function of the high pressure core cooling system is lost and pressure reduction of the nuclear reactor fails, an emergency water source in a condensate water storage tank can be used as a water source for a control rod drive mechanism and therefore safety is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a cooling water supply system for a boiling water reactor that supplies cooling water to a reactor pressure vessel.

(Prior art) In general, in a boiling water reactor, when the reactor water level drops for some reason, a reactor scram system is used to make an emergency shutdown of the reactor, and emergency cooling water is pumped into the reactor pressure vessel. An emergency core cooling system has been installed to supply the reactor.

Figure 2 shows a schematic configuration diagram of a conventional boiling water reactor. In the figure, nuclear fuel is loaded into the reactor pressure vessel 1, and the cooling water that has obtained nuclear energy here turns into steam. is led to the turbine via the main steam pipe. Furthermore, the steam that drives the turbine is condensed in a condenser and returned to the reactor via the water supply system.

In the boiling water reactor configured as described above, if an abnormal situation occurs, such as stopping the water supply from the water supply system to the reactor, the water level in the reactor pressure vessel 1 will drop. The reactor scram system is activated by the water level signal from the reactor water level gauge 2, and the control rod drive system inserts the control rods into the reactor, thereby causing an emergency shutdown of the reactor.

The control rod drive device 3 uses the condensate storage tank 4 as a water source and uses the control rod drive water pump 5 to constantly connect the condensate storage tank outlet piping I.
As a result, cooling water is injected into the reactor. When the reactor water level further decreases, the high-pressure core cooling system is activated, and the high-pressure core cooling pump 6 supplies cooling water to the reactor using the condensate storage tank 4 or subreduction pool 7 as a water source. 9 is a condensate storage tank outlet pipe of the high pressure core cooling system. Furthermore, if water injection by the high-pressure core cooling system is not possible, by depressurizing the reactor, cooling water is injected into the reactor by the low-pressure core cooling system using the subreduction pool 7 as a water source. In this way, even if the water level in the reactor drops for some reason, the reactor can be kept in a stable state by stopping the nuclear reaction in the reactor and sufficiently cooling the reactor core.

The location of the outlet nozzle of the condensate storage tank to the high-pressure core cooling system is such that the amount of water required for the high-pressure core cooling system is stored at the bottom of the condensate storage tank as an emergency water source, and the condensate make-up water is used in multiple systems. It is installed at a lower position than the exit nozzle position to the control rod drive system so that the amount of water can be maintained even when the control rod drive system is in use.

(Problems to be Solved by the Invention) In a boiling water reactor configured as described above, an abnormal situation occurs in which, for example, water supply from the water supply system to the reactor stops and the water level in the reactor pressure vessel decreases. If this occurs,
Even if water injection into the reactor by the high-pressure core cooling system becomes impossible for some reason and reactor depressurization also fails, the reactor will be cooled to some extent by replenishing cooling water from the control rod drive system. . However, if cooling water is not refilled to the condensate storage tank after that and the water level of the condensate storage tank drops to the outlet nozzle position to the control rod drive system, an emergency water source is maintained at the bottom of the condensate storage tank. Despite this, make-up water from the control rod drive system to the reactor is also lost, resulting in insufficient cooling of the reactor core, which may lead to core damage.

The present invention was made in response to such circumstances, and when an abnormal situation occurs such as a drop in the water level in the reactor pressure vessel,
Even in the event of an accident in which the high-pressure core cooling system loses its function and fails to depressurize the reactor, the emergency water source in the condensate storage tank can be used as a water source for the control rod drive system, ensuring the safety of the reactor. The object of the present invention is to provide a cooling water replenishment device for a boiling water reactor that improves performance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the boiling water reactor cooling water replenishment system of the present invention includes condensate storage tank outlet piping to the high-pressure core cooling system. Input the connecting pipe equipped with a normally closed on-off valve that connects the condensate storage tank outlet pipe to the control rod drive system, the reactor water level gauge signal, and the flow rate signal of the high-pressure core cooling system. A control device is provided that opens the on-off valve when cooling water is not supplied from the high-pressure core cooling system into the reactor pressure vessel even though the water level has fallen below a predetermined water level at which the high-pressure core cooling system should operate. It is characterized by this.

(Function) According to the boiling water reactor cooling water replenishment system of the present invention, an abnormal situation such as a drop in the water level in the reactor pressure vessel occurs, the function of the high pressure core cooling system is lost, and the Even if an accident occurs in which the reactor fails to depressurize and cooling water is not refilled to the condensate storage tank, the emergency water source in the condensate storage tank can be used as a water source for the control rod drive system, allowing control It is possible to extend the time during which cooling water can be supplied to the reactor by the rod drive system.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of the present invention.

As shown in the figure, nuclear fuel is loaded into the nuclear urine pressure vessel 1, and the cooling water that has obtained nuclear energy becomes steam.
This steam is led to the turbine via the main steam pipe. The steam that drove the turbine is condensed in a condenser,
It is returned to the reactor via the water supply system.

In the boiling water reactor configured as described above, if an abnormal situation occurs, such as stopping the water supply from the water supply system to the reactor, the water level in the reactor pressure vessel 1 will drop. In response to the water level signal from the reactor water level gauge 2, the reactor scram system is activated and the control rod drive system inserts the control rods into the reactor, and the reactor is brought to an emergency shutdown. The control rod driving device 3 is constantly supplied with cooling water by a control rod driving water pump 5 using a condensate storage tank 4 as a water source, and as a result, cooling water is injected into the reactor. When the reactor water level further decreases, the high-pressure core cooling system is activated, and the high-pressure core cooling pump 6 is activated by the condensate storage tank 4 or the subrection pool 7.
Cooling water is supplied to the reactor using this water source. Furthermore, if water injection by the high-pressure core cooling system is not possible, by depressurizing the reactor, cooling water is injected into the reactor by the low-pressure core cooling system using the subreduction pool 7 as a water source.

As mentioned above, even if the water level in the reactor drops for some reason, the reactor can be kept in a stable state by stopping the nuclear reaction in the reactor and sufficiently cooling the reactor core.

By the way, in this embodiment, the condensate storage tank outlet pipe 9 of the high-pressure core cooling system and the condensate storage tank outlet pipe IO to the control rod drive system are further connected by a connecting pipe 11.
This connecting pipe 11 is provided with an on-off valve l2 that is normally closed. A high-pressure core cooling system flow meter 8, a reactor water level gauge 2, and an on-off valve I2 are electrically connected to the on-off valve control device 13. That is, the on-off valve control device 13 inputs the flow rate signal S1 from the flow meter 8 of the high-pressure core cooling system and the water level signal S2 from the reactor water level gauge 2, and adjusts the reactor water level to a predetermined level at which the high-pressure core cooling system should operate. If it is confirmed that there is no cooling water supplied into the reactor vessel from the high-pressure core cooling system even though the water level has fallen below the water level, the on-off valve 12 is controlled to be opened.

Since this embodiment is configured as described above, an abnormal situation such as a drop in the water level in the reactor pressure vessel may occur.
Controls the emergency water source of the condensate storage tank even in the event of an accident in which the high-pressure core cooling system loses its function and fails to depressurize the reactor, and cooling water is not refilled to the condensate storage tank. It becomes possible to use it as a water source for the rod drive system, extending the duration of cooling water supply to the reactor by the control rod drive system, and improving the reliability of the core health.

[Effects of the Invention] As explained above, according to the boiling water reactor cooling water replenishment system of the present invention, an abnormal situation such as a drop in the water level in the reactor pressure vessel occurs, and the high pressure core cooling system Even if an accident occurs in which the reactor loses its function and fails to depressurize the reactor, and the condensate storage tank is not refilled with cooling water, the control rod drive system will not be able to replenish the reactor with cooling water for a long time. This makes it possible to improve safety compared to conventional methods, leading to improved reliability of nuclear reactors.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional boiling water reactor cooling water supply system. 1...Reactor pressure vessel 2...Water level gauge 3...Control rod drive device 4...Condensate storage tank 5...Control rod drive pump 6...High pressure core cooling pump 7... Subrection pool 8...Flow meter 9...High pressure core cooling system piping 10...Control rod drive system piping 11...Connecting pipe 12...Opening/closing valve I3...Control device (8733) agent Patent attorney Sho Inomata (and 1 other person)

Claims (1)

[Claims] (1) Condensate storage tank outlet piping to the high-pressure core cooling system that supplies condensate storage tank water into the reactor pressure vessel, and condensate storage tank outlet piping to the control rod drive system that supplies condensate storage tank water to the control rod drive device. A condensate storage tank outlet pipe, a connecting pipe with a normally closed on-off valve that connects the condensate storage tank outlet pipes, a water level signal from a reactor water level gauge, and a flow rate signal of a high pressure core cooling system. is input, and the on-off valve is opened when cooling water is not being supplied from the high pressure core cooling system to the reactor pressure vessel even though the reactor water level has fallen below the predetermined water level at which the high pressure core cooling system should operate. A cooling water supply system for a boiling water reactor, characterized in that it is equipped with a control device.