JPS5841478B2 - reactor cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear reactor cooling system that operates in a nuclear power plant when the reactor is shut down or when a reactor cooling water loss accident occurs.

At nuclear power plants, water from a water storage tank is pumped into the reactor vessel through a pump in the reactor cooling system to remove residual heat when the reactor is shut down or to secure cooling water in the event of a loss of coolant accident. It is designed to cool the reactor.

This reactor cooling system has a configuration as shown in FIG. 1, for example, and has a main water source installed outside the reactor building a.
A water supply mechanism e that pumps cooling water supplied from the main water source or the suppression pool C into the reactor vessel d, and a switching valve mechanism f, g that selectively switches to either the main water source or the suppression pool C. It is composed of:

Cooling water is, in principle, configured to be supplied into the reactor vessel d from a clean main water source, and when the cooling system starts operating, the switching valve f for the main water source is first opened, and the switching valve f for the suppression The switching valve g is closed and cooling water from the main water source is introduced into the reactor vessel d.

When the water level in the main water source falls below a predetermined value, the suppression pool switching valve g is opened, and the main water source switching valve f is closed, and the water in the suppression pool C is It is introduced into the furnace vessel d.

However, in the cooling system with the above configuration, there is a possibility that the main water source installed outdoors or the long piping will break in the event of an earthquake, and in this case, cooling water cannot be normally supplied to the reactor vessel d. There is a risk that it will disappear.

Therefore, the above-mentioned main water source and piping are required to have strict earthquake resistance, which takes time and effort, but it is difficult to ensure complete earthquake resistance for long outdoor piping, etc., and the above-mentioned dangers Sexuality has not yet been completely eliminated.

This invention was made based on the above circumstances, and its purpose is to maintain the water source without cutting off the supply of cooling water to the reactor vessel even if the water supply from the main water source is inadvertently cut off. Can be switched to a suppression pool,
An object of the present invention is to provide a nuclear reactor cooling system that can further improve the safety of a nuclear reactor.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

In the figure, numeral 1 indicates a nuclear reactor building, and a reactor containment vessel 2 is provided within this reactor building 1.

A reactor vessel 3 is installed within the reactor containment vessel 2, and a suppression pool 4 is also formed.

Further, 5 is a main water source provided outside the reactor building 1, and this main water source 5 contains clean cooling water.

Further, a water supply mechanism 6 for pumping cooling water supplied from the main water source 5 or the suppression pool 4 into the reactor vessel 3 is connected to the reactor vessel 3 .

This water supply mechanism 6 includes a water supply pump 8 in the middle of the water supply piping 7.
, a check valve 9, a gate valve 10, and a check valve 11 are provided in this order.

A water supply pipe 12 is connected between the water supply mechanism 6 and the main water source 5.
．． 13, and the water supply mechanism 6 and the suppression pool 4 are also connected by another water supply pipe 14.

The piping 12.14 is provided with an electric switching valve 15a15b serving as a switching valve mechanism for selectively switching to either the main water source 5 or the suppression pool 4.

Note that 16 and 17 are check valves.

And piping 12.1 connecting the water supply mechanism 6 and the main water source 5
An auxiliary tank 20 is provided in the middle of the tank 3.

This auxiliary tank 20 is installed inside the reactor building 1.

The auxiliary tank 20 has a sufficient capacity to maintain water supply into the reactor vessel 3 until the switching operation of the switching valves 15a, 15b is completed, and a water level detector 21 serves as a water supply detection mechanism. have.

This water level detector 21 closes the switching valve 15a for the main water source and opens the switching valve 15b for the suppression pool when the water level A in the auxiliary tank 20 becomes equal to or lower than the water source change setting water level B. It is configured to output a signal that causes

Next, the operation of the above configuration will be explained.

When a signal is issued to start the reactor cooling system when the reactor is shut down or a reactor cooling water loss accident occurs, the water pump 8 is activated and the gate valve 10 is opened.

On the other hand, since the auxiliary tank 20 is supplied with cooling water from the main water source 5 and is fully filled with water, the water level detector 21 does not output a water source change signal.

Therefore, the switching valve 15a for the main water source is opened, and the switching valve 15b for the suppression pool is closed, so that the cooling water from the main water source 5 is supplied to the auxiliary pump 20 by the water pump 8.
The reactor is then pumped through pipes 12 and 7 into the reactor vessel 3, where it cools the reactor core.

As a result, the water level of the main water source 5 gradually decreases, and finally the supply of cooling water to the auxiliary tank 20 stops.

Then, the water level in the auxiliary tank 20 starts to decrease, and when the water level A becomes lower than the water source change setting water level B, the water level detector 21
detects this and issues a signal to close the main water source switching valve 15a and open the suppression pool switching valve 15b.

Until the switching operation of each switching valve 15a, 15b is completed, the water supply from the auxiliary tank 20 is continued, and the water source is switched to the suppression pool 4 without cutting off the cooling water while switching the valves. After that, cooling water is pumped into the reactor vessel 3 from the suppression pool 4.

Note that the flow of the above-mentioned signals is shown in FIG.

According to the device of the above embodiment, even if the outdoor piping 13 breaks due to an earthquake or the like or the main water source 5 is damaged and water supply to the auxiliary tank 20 is stopped, the auxiliary tank 20 When a drop in the water level is detected by the water level detector 21, the switching valves 15a and 15b are switched immediately, and the water source is switched to the suppression pool 4, so that the flow of cooling water sent into the reactor vessel 3 is continuous without interruption. cooling water can be supplied.

Therefore, it is possible to reliably suppress the temperature rise in the core.

Moreover, the auxiliary tank 20 has a switching valve 15a. Since the capacity is sufficient to maintain the water supply to the reactor vessel 3 until the switching operation of valve 15b is completed, the water supply does not stop when the valve is switched, and cooling water is supplied normally from beginning to end. can.

Further, according to this embodiment, since the water level detector 21 is adopted as the water supply detection mechanism, it is possible to reliably detect the stoppage of water supply from the main water source 5, and also to detect the changeover valve in relation to the residual water amount in the auxiliary tank 20. Since switching control of the switching valves 15a and 15b is possible, the operation is reliable and the switching timing of the switching valves 15a and 15b can be accurately determined.

In the above embodiment, an electric switching valve is used as the switching valve mechanism, but it is of course possible to use an air-operated valve or a valve of other structure. It goes without saying that the water supply mechanism, the switching valve mechanism, the auxiliary tank, the water supply detection mechanism, and the piping and wiring structures connecting these can be configured in various ways as long as they do not go against the gist of the present invention.

As explained above, in this invention, an auxiliary tank is provided between the water supply mechanism and the main water source, and this auxiliary tank is installed inside the reactor building. Even if the reactor is damaged, the water source can be immediately switched to the suppression pool before the cooling water supply is interrupted, allowing continued cooling of the reactor core.

The auxiliary tank can supply cooling water to the reactor vessel until the switching operation of the switching valve is completed, so the supply of cooling water does not stop during the switching operation of the valve, and the reactor core can be reliably cooled. Safety can be further improved.

Moreover, according to the present application, normal cooling water can be secured even if an outdoor water supply pipe etc. breaks, so it is possible to reduce the seismic structure of various equipment installed outside the reactor building. There is also the secondary effect of simplifying the construction work.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram diagrammatically showing a conventional nuclear reactor cooling system, and FIGS. 2 and 3 show an embodiment of the present invention L7,
FIG. 2 is a schematic diagram of the reactor cooling system, and FIG. 3 is a flowchart showing the flow of signals output from the water level detector. 1... Reactor building, 3... Reactor vessel, 4
・・・・Suppression boule, 5・・Main water source, 6・River・・Water supply mechanism, 15 a, 15 b・
...Switching valve mechanism (switching valve), 20... Auxiliary tank, 21... Water supply detection mechanism (water level detector).

Claims (1)

[Scope of Claims] 1. A main water source provided outside the reactor building, a water supply mechanism that pumps cooling water supplied from the main water source or the suppression pool into the reactor vessel, and any of the main water source or the suppression pool. The reactor is equipped with a switching valve mechanism that selectively switches between the water supply mechanism and the main water source, and is installed in the reactor building between the water supply mechanism and the main water source, and until the switching operation of the switching valve mechanism is completed, the reactor An auxiliary tank having a sufficient capacity to maintain water supply into the container is provided, and the switching valve mechanism detects whether or not water is being sent from the main water source to the auxiliary tank, and when the water supply from the main water source is stopped. A nuclear reactor cooling system characterized by being provided with a water supply detection mechanism that switches and operates. 2. The reactor cooling system according to claim 1, wherein the water supply detection mechanism is a water level detector that detects the water level of the auxiliary tank.