JPH0312279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high-pressure core cooling system for, for example, a boiling water nuclear reactor.

[Technical Background of the Invention] Generally, in boiling water reactors, cooling water is injected into the core in the event of an accident to cool the core, and high-pressure core cooling is used to prevent the fuel cladding tubes housed in the core from becoming brittle. equipment is installed. This high-pressure core cooling system is also used to maintain the reactor water level during plant transitions.

This high-pressure core cooling system generally has a condensate storage tank and a suppression pool as water sources, and during plant transients, the condensate storage tank water of good quality can be injected into the core.
The water source is said to be a condensate storage tank. When the condensate storage tank water decreases or the suppression pool water increases, water source switching occurs automatically and the water source is switched to the second water source, the suppression pool.

When this high-pressure core cooling system operates during plant transients, the amount of water injected generally exceeds the amount of reactor water reduction, resulting in a high reactor water level, and in this case, the injection valve installed in the injection line closes. and the reactor injection operation is switched to minimum flow bypass operation. Then, when water injection into the reactor is stopped and the reactor water level drops, the injection valve is opened again and a reactor injection operation is performed in which cooling water is injected into the reactor.

In other words, when considering the reliability of the cooling water pump, it is undesirable to start and stop the cooling water pump frequently, and generally when cooling water is not being injected into the reactor pressure vessel, the cooling water pump should not be started or stopped frequently. Minimum flow bypass operation is performed in which the minimum allowable flow rate of cooling water is supplied to the cooling water pump, and operation is performed in the flow path between the water source, the pump, and the water source.

[Problems in the Background Art] However, in conventional high-pressure core cooling systems, only the minimum flow bypass line is installed to the suppression pool.
In the case of minimum flow bypass operation, water source switching occurs following the rise in the suppression pool water level, cooling water in the suppression pool flows into the injection line, and high quality condensate storage tank water is transferred. It has become impossible to inject into the reactor pressure vessel for a long period of time.

In other words, the cooling water stored in the suppression pool generally contains impurities such as iron and cobalt, and when there is no accident such as during a plant transition, the cooling water stored in the condensate storage tank should be kept as much as possible. It is desirable to inject high quality cooling water into the reactor pressure vessel.

[Object of the Invention] The present invention has been made in response to the above-mentioned conventional situation, and is a high-pressure system that prevents the cooling water in the suppression pool from flowing out into the injection line even during the minimum flow bypass operation of the cooling water pump. The aim is to provide a core cooling system.

[Summary of the Invention] That is, the present invention provides an injection line that connects a reactor pressure vessel and a condensate storage tank, and in which a tank-side suction valve, a cooling water pump, and an injection valve are arranged in order from the condensate storage tank side. and a pool water pipe having a pool-side suction valve that connects between the tank-side suction valve and the cooling water pump and the suppression pool, and between the cooling water pump and the injection valve and the suppression pool. a pool-side bypass line equipped with a pool-side bypass valve that connects the cooling water pump and the injection valve, and a tank-side bypass line that connects the cooling water pump and the injection valve with the condensate storage tank and equipped with a tank-side bypass valve; A tank-side bypass valve control device that opens the tank-side bypass valve and performs bypass operation using the tank-side bypass line when the flow rate of the injection line decreases below a preset value during operation using the condensate storage tank as a water source. and a pool-side bypass valve that opens the pool-side bypass valve to perform bypass operation using the tank-side bypass line when the flow rate of the injection line decreases below a preset value during operation using the suppression pool as a water source. [Embodiment of the Invention] The details of the present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 1 shows a high-pressure core cooling system according to an embodiment of the present invention. In the figure, reference numeral 1 connects a reactor pressure vessel 2 and a condensate storage tank 3. side suction valve 4, check valve 5,
An injection line in which a cooling water pump 6, an injection valve 7, and a check valve 8 are arranged is shown.

A suppression pool 9 is connected between the check valve 5 of the injection line 1 and the cooling water pump 6, and the pool side suction valve 1 is connected in order from the suppression pool 9 side.
Pool water piping 1 where 0 and check valve 11 are installed
2 are connected. A pool-side bypass line 14 is connected between the cooling water pump 6 and the injection valve 7 of the injection line 1 and is connected to a suppression pool 9 and into which a pool-side bypass valve 13 is inserted. A tank side bypass line is branched from the pool side bypass valve 13 upstream of the pool side bypass line 14 and is connected to the condensate storage tank 3. A stop valve 15 and a tank side bypass valve 16 are inserted from the condensate storage tank 3 side. 17 are connected.

The condensate storage tank 3, the suppression pool 9, and the reactor pressure vessel 2 are equipped with a condensate storage tank water level gauge 18, a suppression pool water level gauge 19, and a reactor water level gauge 2 for measuring their respective water levels.
0 is placed. Further, a flow meter 21 is disposed between the connection point of the pool-side bypass line 14 of the injection line 1 and the injection valve 7 to measure the flow rate of the cooling water flowing through the injection line 1 .

In the figure, the numbers 22, 23, 24, 25, 2
Reference numerals 6 and 27 indicate control devices for opening and closing various valves provided in this high-pressure core cooling system, respectively. That is, the reference numeral 22 indicates a pool-side suction valve control device that opens and closes the pool-side suction valve 10, and this pool-side suction valve control device 22, as shown in FIG. The water level signal from the suppression pool water level gauge 19 is input, and the pool is activated when the water level in the condensate storage tank 3 is lower than a predetermined value or the water level in the suppression pool 9 is higher than a predetermined value. The side suction valve 10 is opened.

In FIG. 1, reference numeral 23 indicates a tank-side suction valve control device that controls opening and closing of the tank-side suction valve 4, and this tank-side suction valve control device 23 is connected to the pool-side suction valve 10 as shown in FIG. The opening/closing signal for the pool side suction valve 10 is input, and when the pool side suction valve 10 is fully opened, the tank side suction valve 4 is closed.

In FIG. 1, reference numeral 24 indicates a pool side bypass valve control device that controls the opening and closing of the pool side bypass valve 13, and this pool side bypass valve control device 24 is connected to the pool side suction valve 10 as shown in FIG.
The opening/closing signal and the flow rate signal from the flow meter 21 are input, and it is determined that the pool side suction valve 10 is not fully closed.
When the flow rate value of the flow meter 21 is lower than a predetermined value, the pool side bypass valve 13 is opened, and when the flow rate value input from the flow meter 21 is higher than a predetermined value, the pool side bypass valve 13 is opened. 13 is closed.

In FIG. 1, reference numeral 25 indicates a tank-side bypass valve control device that controls opening and closing of the tank-side bypass valve 16, and this tank-side bypass valve control device 25, as shown in FIG.
0 open/close signal, the flow rate signal of the flow meter 21, and the open/close signal of the pool-side bypass valve 13 are input, the pool-side suction valve 10 is fully closed, and the flow rate value from the flow meter 21 is lower than a predetermined value. The tank side bypass valve 16 is opened, and the tank side bypass valve 16 is closed when the flow rate value from the flow meter 21 is higher than a predetermined value or when the pool side bypass valve 13 is fully open.

In FIG. 1, reference numeral 26 indicates a stop valve control device that controls the opening and closing of the stop valve 15. As shown in FIG. When an open/close signal is input from the pool side bypass valve 13 or the pool side suction valve 10 is fully open, the stop valve 15 is closed.

In the high-pressure core cooling system configured as described above, in the event of a reactor accident or plant transition, the high-pressure core cooling system performs automatic reactor injection operation to replenish sufficient cooling water into the reactor pressure vessel. When the reactor water level is secured, the injection valve 7 is automatically closed by the high water level signal from the reactor water level gauge 20, and the condensate storage tank 3 or the supplement is closed by the low flow signal from the flow meter 21. Chillon pool 9
The minimum flow bypass valve on the side is opened, and the high-pressure core cooling system is placed in minimum flow bypass operation.

That is, since the condensate storage tank 3 is normally used as a water source, the tank side bypass valve 16 is automatically opened by the tank side bypass valve control device 25 upon receiving a low flow signal, and the condensate storage tank 3 and the cooling water pump are automatically opened. 6. A minimum flow bypass operation is performed in the flow path of the condensate storage tank 3. Therefore, the cooling water in the condensate storage tank 3 will not flow into the suppression pool 9, and the water source will not be switched to the suppression pool 9 due to the high water level signal of the suppression pool 9. Then, when the reactor water level becomes low again, the injection valve 7 is automatically opened, and the tank side bypass valve 16 is closed by the flow rate high signal input to the tank side bypass valve control device 25, and the reactor injection operation is started. .

In addition, in the high-pressure core cooling system configured as described above, when the water level of the condensate storage tank 3 becomes low or the water level of the suppression pool 9 becomes high during reactor injection operation, the pool side suction valve 10 is opened by the pool side suction valve control device 22, and when the pool side suction valve 10 is fully opened, the tank side suction valve 4 is opened.
is closed by the tank-side suction control device 23, and the suppression pool 9 is switched to water source operation.

When the minimum flow rate bypass operation is started here, the pool side suction valve 10 has opened, so the pool side bypass valve control device 24 and the tank side bypass valve control device 25 control the pool side bypass valve 13.
is opened, and the pool side bypass line 14 is used. Also, at this time, since the pool-side suction valve 10 is fully open, the stop valve control device 26 closes the stop valve 15.

Furthermore, in the high pressure core cooling system configured as described above, the condensate storage tank 3, the cooling water pump 6,
When water source switching occurs during the minimum flow rate bypass operation of the condensate storage tank 3, the pool side suction valve control device 22 and the tank side suction valve control device 23 work together to switch the tank side suction valve 4 and the pool side suction valve. 10
The pool side bypass valve 13
is fully opened by the pool-side bypass valve control device 24, and then the tank-side bypass valve 16 is closed. At this time, even if the tank-side bypass valve 16 to the condensate storage tank 3 does not close due to a failure, the tank-side bypass line 17 will always be closed because the stop valve 15 will be closed at the same time. Become.

[Effects of the Invention] As described above, according to the high-pressure core cooling system of the present invention, when performing minimum flow bypass operation using the condensate storage tank as a water source, the tank-side bypass line connected to the condensate storage tank can be This makes it possible to prevent water source switching to the suppression pool during minimum flow bypass operation that uses the condensate storage tank water source, and to ensure that high-quality cooling water is kept in the reactor pressure vessel for a longer period of time. It becomes possible to inject into.

[Brief explanation of the drawing]

FIG. 1 is a piping system diagram showing an embodiment of the present invention;
Figure 2 is a block diagram of the pool side suction valve control device.
Figure 3 is a block diagram of the tank side suction valve control device.
FIG. 4 is a block diagram of the pool side bypass valve control device, FIG. 5 is a block diagram of the tank side bypass valve control device, and FIG. 6 is a block diagram of the stop valve control device. 1...Injection line, 2...Reactor pressure vessel, 3
... Condensate storage tank, 4 ... Tank side suction valve, 6
... Cooling water pump, 7 ... Injection valve, 10 ... Pool side suction valve, 12 ... Pool water piping, 13 ... Pool side bypass valve, 14 ... Pool side bypass line, 16 ... Tank side bypass valve , 17...tank side bypass line.

Claims (1)

[Claims] 1 Connect the reactor pressure vessel and the condensate storage tank, and sequentially from the condensate storage tank side, the tank side suction valve,
a cooling water pump, an injection line in which an injection valve is arranged, and a pool water pipe provided with a pool side suction valve that connects between the tank side suction valve and the cooling water pump and the suppression pool; A pool-side bypass line having a pool-side bypass valve connecting between the cooling water pump and the injection valve and the suppression pool, and connecting between the cooling water pump and the injection valve and the condensate storage tank. When the flow rate of the injection line decreases below a preset value during operation using the condensate storage tank as a water source, the tank side bypass line is equipped with a tank side bypass valve, and when the flow rate of the injection line decreases below a preset value, the tank side bypass valve is opened and the tank side bypass line is opened. A tank side bypass valve control device performs bypass operation using a side bypass line, and when the flow rate of the injection line decreases below a preset value during operation using the suppression pool as a water source, the pool side bypass valve is opened. A high-pressure core cooling system comprising: a pool-side bypass valve control device that performs bypass operation using the tank-side bypass line.