JPH06214081A - Vent device for nuclear reactor containment vessel - Google Patents

Abstract

PURPOSE:To improve reliability without using a dynamic equipment for a driv ing source. CONSTITUTION:A dry well 18 and a wet well 19 in a nuclear reactor containment vessel 17 are connected to an airtight vessel 1 through a first connecting piping 3. The gas phase part 1a of the airtight vessel 1 is connected to the top part of a feed water tank 6 through a second connecting piping 7. A third connecting piping 12 and a release piping are connected to the top part of the feed water tank 6. The feed water tank 6 is connected to a scrubbing water storing tank 11 through the third connecting piping 12 and a connecting valve 13. The lower part of the feed water tank 6 is connected to the lower part of the airtight vessel 1 through a feed valve 10. A release piping 4 communicating with an atmospheric release hole 5 is connected to the top end of the airtight vessel 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor containment vessel venting device for supplying scrubbing water by a gravity drop method used in a nuclear power plant.

[0002]

2. Description of the Related Art A reactor containment vessel used in a nuclear power plant isolates the reactor from the external environment when an accident occurs, and radioactive fission products (hereinafter referred to as FP) are placed outside the reactor pressure vessel. Even when it is released, it serves as a barrier to the release of FP to the external environment and is installed for the purpose of preventing radioactivity from being released to the external environment.

As shown in FIG. 2, a reactor containment vessel 17 of a boiling water reactor (hereinafter referred to as BWR) installed upright in a reactor building 16 generally has two compartments, a dry well 18 and a wet well 19. It is divided. A reactor pressure vessel 20 is housed in the dry well 18, and a pressure suppression water 21 is stored in the wet well 19.

A pipe (not shown) connected to the reactor pressure vessel 20 is broken, and the high-temperature and high-pressure primary cooling water is transferred to the dry well 18
At the time of an accident (hereinafter referred to as LOCA) that is discharged to the reactor, the atmospheric gas containing steam as a main component in the dry well 18 is introduced into the pressure suppression water 21 through the vent pipe 22 to be cooled and condensed, and the reactor containment vessel 17 It has a structure that suppresses the rise in internal pressure.

At the time of LOCA, an emergency core cooling system (not shown) is activated to replenish the lost primary cooling water to secure core cooling, and at the same time, heat is removed from the pressure suppression water 21 to remove decay heat. A system (not shown) is activated to suppress the temperature rise of the pressure suppression water 21.

In a nuclear power plant having such a reactor containment vessel, it is impossible in reality.
An accident where an abnormal event occurs and the cooling water supply means to the reactor pressure vessel 20 is lost for both regular and emergency use, and the core cooling function is completely lost, or the reactor containment vessel
Accident that the heat removal function from 17 is completely lost (hereinafter,
Severe accidents) and still take measures to prevent the safety of the nuclear power plant from being lost.

Probabilistic safety assessments have revealed that the probability of occurrence of severe accidents is extremely low. However, in view of the importance of the result of releasing a large amount of FP into the environment, nuclear reactors at times of severe accidents in various foreign countries in recent years. A device for preventing damage to the containment vessel is under consideration.

As a measure for preventing damage to the reactor containment vessel in the event of a severe accident, the atmosphere gas inside the reactor containment vessel 17, which has been subjected to FP removal before reaching the damage pressure at which the reactor containment vessel 17 is damaged by pressure, is used as an environment. An example is a containment vessel vent that is released to the reactor and suppresses the rise of the reactor containment vessel 17.

Among the containment vessel venting apparatus for performing containment vessel venting, when the gas containing FP passes through the liquid phase, it becomes bubbles and is removed in the process of rising in the liquid phase. For example, Japanese Patent Application Laid-Open No. 3-077096 discloses a method that employs a method of removing the above.

That is, as shown in FIG. 2, from the dry well 18 and the wet well 19, the suction pipe 23 and the scrubbing pipe 25 are respectively connected to the scrubbing water 2 in the airtight container 1 through the connecting valve 24 and the scrubbing valve 26. It is connected to the communication pipe 3 where the part is submerged. Then, the discharge pipe 4 is connected to the communication pipe 3, and the upstream side of the discharge pipe is connected to the atmosphere discharge port and the gas phase portion in the airtight container 1.

[0011]

However, the atmospheric gas in the reactor containment vessel introduced from the reactor containment vessel to the containment vessel venting apparatus is at a high temperature, and the decay heat of FP contained in the gas is also generated. As the scrubbing liquid, scrubbing water 2 containing water as a main component is used, but scrubbing water 2 of the atmospheric gas in the reactor containment vessel is used.
By the heat donation to the scrubbing water 2,
The decrease is inevitable.

In the case of the containment vessel venting apparatus which employs the FP removal method utilizing the scrubbing effect as described above, it is inevitable that the scrubbing water 2 is reduced when used in a severe accident.

Assuming an apparatus of the type that does not supply scrubbing water from the outside during use, the function of the apparatus must be maintained in consideration of the decrease in scrubbing water, and therefore the scale of the apparatus is reduced. It will be enormous, and it is unrealistic from the viewpoint of cost and the actual situation of the existing plant.

Therefore, although a device of the type that supplies the scrubbing water 2 from the outside during use is practical,
This device is intended for use in severe accidents, and must have high reliability when considering the importance of its function.

Dynamic equipment is unreliable in view of its failure rate and the frequency of occurrence of events such as loss of all AC power during a severe accident. Therefore, the method of supplying scrubbing water to the containment vessel vent device using a dynamic device such as a pump has a problem of loss of function.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a reactor containment vessel venting apparatus which is highly reliable and does not require an AC power source for its driving.

[0017]

According to the present invention, there is provided an airtight container having a liquid phase portion for storing scrubbing water at a lower portion thereof, and a self-weight of the stored water which is installed at a position higher than the liquid surface of the liquid phase portion. Water tank for supplying water to the water supply tank, a water storage tank for scrubbing that is installed at a higher position than this water tank and supplies water to the water supply tank with the head pressure of the stored water, and a bottom of the water storage tank for scrubbing and a water supply tank for the scrubbing water are connected. A connecting pipe that guides the water from the storage tank to the water supply tank, a connecting valve that is installed on this connecting pipe and that is normally closed and that opens when water is supplied to the water supply tank, and a water supply tank that is installed at the top of the water supply tank when supplying water to the water supply tank. A relief pipe for releasing the atmosphere in the water tank to the outside, and an on-off valve installed in this relief pipe that opens normally when water is supplied to the water tank in a normally closed state. , A connecting pipe that connects the gas phase part of the airtight container to the top of the water tank and connects the atmosphere inside the airtight container to the upper part of the water tank, and it is installed in this connecting pipe and is normally closed and opens when supplying water to the airtight container. A water supply pipe that connects the liquid phase part of the airtight container and the bottom of the water supply tank to guide the scrubbing water in the water supply tank into the airtight container, and the water supply pipe installed in this water supply pipe and normally closed to supply water to the airtight container. It is characterized by comprising a water supply valve which is sometimes opened.

[0018]

Operation The atmospheric gas in the reactor containment vessel containing FP generated at the time of a severe accident is introduced into the scrubbing water in the airtight vessel through the first connecting pipe and passes through the scrubbing water.

The FP is removed by the scrubbing effect in the process in which the gas becomes bubbles and rises in the water. However, due to the high temperature of the gas and the heat of decay of the FP, heat is supplied to the scrubbing water so that part of the scrubbing water is removed. Evaporate and reduce scrubbing water in the airtight container. Due to this decrease in scrubbing water, scrubbing water will be supplied when a significant decrease in the scrubbing effect is confirmed.

In the present invention, a water supply tank for supplying scrubbing water into the airtight container is installed at a position higher than the liquid level of the scrubbing water in the airtight container which is the main body of the reactor containment vessel venting device, and , A scrubbing water storage tank for supplying scrubbing water to the water supply tank is installed at a position higher than the water supply tank.

A connecting valve connected to a second connecting pipe connecting the gas phase portion of the airtight container to the top of the water tank, and a water connecting pipe connecting the scrubbing water in the airtight container to the bottom of the water tank. The stored water in the water supply tank is introduced into the airtight container by the pressure applied to the liquid level and the weight of the stored water by the opening operation of the water supply valve.

After the water supply into the airtight container is completed, the airtight container and the water supply tank are separated by closing the connection valve of the second communication pipe and the water supply valve of the water supply pipe. As a result, scrubbing water is supplied into the airtight container.

Next, the opening operation of the opening / closing valve installed in the relief pipe connected to the top of the water supply tank releases the atmosphere inside the water supply tank, which has the same pressure as the gas phase portion of the airtight container, to the outside. By the opening operation of the communication valve connected to the third communication pipe connecting the water supply tank and the scrubbing water storage tank, the stored water in the scrubbing water storage tank is caused to flow through the third communication pipe by its head pressure. Install in water tank.

After the water supply to the water supply tank is completed, the water supply tank and the scrubbing water storage tank and the external atmosphere are isolated by closing the connection valve of the second communication pipe and the opening / closing valve of the relief pipe. As a result, scrubbing water is supplied to the water supply tank.

When water is again supplied to the airtight container, the above operation is repeated. In this way, scrubbing water for maintaining the function of the containment vessel venting device can be supplied by a highly reliable method without using an AC power source or the like as a drive source.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reactor containment vessel vent device according to the present invention will be described with reference to FIG. In addition, in FIG.
The same parts as those in FIG. 2 are designated by the same reference numerals, and the description of the overlapping parts will be omitted. Therefore, the description of the inside of the reactor containment vessel 17 on the left side in FIG. 1 will be omitted.

That is, the scrubbing water 2 is contained in the airtight container 1 of the reactor containment vessel venting device, and the first connecting pipe 3 for introducing the atmospheric gas in the reactor containment container 17 into the scrubbing water 2 is connected. Has been done. The airtight container 1 is connected with a discharge pipe 4 for discharging the gas in the gas phase portion 1a from the atmosphere discharge port 5 to the outside environment.

In order to guide the gas in the gas phase portion 1a of the airtight container 1 to the water supply tank 6, the gas phase portion 1a of the airtight container 1 and the main part of the water supply tank 6 are connected by the second connecting pipe 7. The second communication pipe 7 is provided with a communication valve 8 which is normally closed and is opened when water is supplied. Further, since the stored water in the water supply tank 6 is guided to the airtight container 1, the gas phase portion 1 of the airtight container 1
a and the bottom of the water supply tank 6 are connected by a water supply pipe 9. A water supply valve 10 that is normally closed and opens when water is supplied is connected to the water supply pipe 9.

In order to guide the stored water to the water supply tank 6 for the scrubbing water storage tank 11, the scrubbing water storage tank
The bottom of 11 and the top of the water supply tank 6 are connected by a third connecting pipe 12. The third communication pipe 12 is provided with a communication valve 13 which is normally closed and is opened when water is supplied. A relief pipe 14 is connected to the top of the water supply tank 6 in order to release the atmosphere inside the water supply tank 6 to the outside. An on-off valve 15 that is normally closed and opens when water is supplied is connected to the relief pipe 14.

The water supply tank 6 must store a quantity of supply water corresponding to the amount of evaporation of the scrubbing water 2 which causes a significant reduction in the scrubbing effect of the airtight container 1, and the stored water is completely stored. Since it is necessary to supply water to the airtight container 1, it is installed at a position sufficiently higher than the liquid level of the scrubbing water 2 in the airtight container 1.

The scrubbing water storage tank 11 supplies water to the water supply tank 6 by the head pressure of the stored water.
It is installed so that its bottom is higher than the main part of the water tank.

Further, each valve in the figure uses a DC motor operated valve, an air operated valve, etc. so that it can function even in the event of a loss of all AC power supplies.

[0033]

According to the present invention, it is possible to supply scrubbing water, which has been vaporized and reduced by scrubbing of the gas generated at the time of a severe accident in the reactor containment vessel venting device, only by a physical action that works naturally.

As a result, as compared with the method of supplying scrubbing water to the containment vessel venting device using a dynamic device such as a pump, it does not require an AC power source as a drive source and has high reliability, The reliability of the reactor containment vessel vent device having this scrubbing water supply device is also improved.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing an embodiment of a reactor containment vessel vent device according to the present invention.

FIG. 2 is a schematic system diagram showing a conventional reactor containment vessel venting device.

[Explanation of symbols]

1 ... Airtight container, 1a ... Gas phase part, 2 ... Scrubbing water,
3 ... 1st communication piping, 4 ... discharge piping, 5 ... atmosphere discharge port,
6 ... Water tank, 7 ... Second communication pipe, 8 ... Communication valve, 9
… Airtight container water supply pipe, 10… Water supply valve, 11… Scrubbing water storage tank, 12… Third communication pipe, 13… Communication valve, 14…
Relief piping, 15 ... On-off valve, 16 ... Reactor building, 17 ... Reactor containment vessel, 18 ... Dry well, 19 ... Wet well, 20
… Reactor pressure vessel, 21… Pressure suppression water, 22… Vent pipe, 23
… Suction line, 24… Communication valve, 25… Scrubbing line, 26…
Scrubbing valve.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G21C 13/00

Claims (1)

[Claims] 1. An airtight container for containing scrubbing water, which is connected through a first connecting pipe connecting a dry well and a wet well in a reactor containment vessel, and a gas phase portion of the airtight container to a second portion. A water supply tank connected to the top of the water supply tank via a communication pipe, a scrubbing water storage tank connected to the water supply tank via a third communication pipe at a position higher than the water supply tank, and the airtight A discharge pipe connected to the tank, a water supply pipe connected between the lower part of the airtight container and the lower part of the water supply tank, a relief pipe connected to the top of the water supply tank, and each of the pipes. A reactor containment vessel venting device, comprising: