JP3449583B2 - Condensate storage equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a condensate storage facility for a nuclear power plant.

[0002]

2. Description of the Related Art Due to the effects of the TMI accident in the United States and the Chernobyl accident in the former Soviet Union, measures for severe events have been discussed in order to mitigate the effects of severe events in nuclear power plants. .

In the United States, a boiling water nuclear power plant having a Mark 1 type containment vessel has been required by regulatory authorities to install a pressure resistant vent system. In addition, a filter vent system equipped with a filter for reducing the amount of radioactive material emission has begun to be introduced into a pressure resistant vent system in a European nuclear plant.

On the other hand, in Japan's nuclear power plants, the safety is higher than that of the nuclear power plants in various countries of the world, and it is considered that the severe event is an event that cannot occur from an engineering point of view. Therefore, although it is not obligatory to implement countermeasures against severe events, each nuclear power plant is studying the judgment of the effectiveness of voluntary implementation from the standpoint of pursuing further safety.

Assuming the occurrence of a large-scale earthquake, the external power source has only the seismic resistance equivalent to that of general industry, and all the emergency diesel generators that have been conventionally installed function due to a common cause failure. If the possibility of not being able to maintain is not zero, the total AC power loss event (Station Black Ou
(hereinafter, t, SBO) may occur even during severe events.

An event when this SBO occurs will be described with reference to FIG. During normal operation, the nuclear reactor 2 accommodating the core 3 sends steam to the turbine equipment (not shown) outside the nuclear reactor containment vessel 1 via the main steam pipe 6.
When SBO occurs in the reactor containment vessel 1, the main steam isolation valve 5 closes and the electric cooling pump (not shown) does not operate, so that the pressure of the reactor 2 increases. As a result, the relief safety valve 4 installed in the main steam pipe 6 is automatically opened, and the steam is guided to the suppression pool 7 in the reactor containment vessel 1 through the exhaust pipe 8 connected to the relief safety valve 4 and condensed. At this time, the reactor pressure rises and the reactor water moves to the suppression pool 7 to lower the reactor water level. However, in a conventional nuclear power plant, a steam-driven reactor isolation cooling system that does not depend on an AC power source is used. 9 is installed, and water injection into the core by this system will be performed using the water source of the condensate storage tank 10.

Next, a conventional technique of the condensate storage tank will be described with reference to FIG. The condensate storage tank 10 has an emergency water source 14 used for injecting water into the core at the time of an accident and a regular water source 13 during normal operation in one tank. The regular water source 13 is intended to secure a water source to be used at the time of periodic inspection and to absorb the pressure difference of the water held in the reactor during operation / shutdown and the water amount difference due to the difference in water level conditions. On the other hand, the emergency water source 14 has a regular water source nozzle 11 installed above the emergency water source 14 in order to ensure the securing of the water source supplied in the event of an accident. With this arrangement, when the water level drops below the regular water source nozzle 11, the regular water cannot be supplied any more, while the emergency water supplied in the event of an accident is at the bottom of the condensate storage tank 10. It can be supplied from the provided emergency water source nozzle 12.

FIG. 8 shows a conventional technique adopting a filter vent system. This conventional example is a filter vent that secures the required water immersion in the condensate storage tank 10 for depressurizing and scrubbing the vapor containing radioactive substances such as radioactive iodine released in the suppression pool when a severe event occurs. In this example, the filter vent water source 16 in which the pipe 15 is installed is secured by the partition wall 17 or the like. One of the filter vent pipes 15 is connected to a gas phase portion in a suppression pool (not shown), and the other is connected to a filter vent water source 16 as shown in FIG.

In this embodiment, a discharge pipe 24 is provided in the upper space of the condensate storage tank 10 to reach the exhaust pipe 21 which dilutes and discharges the radioactive radioactive exhaust gas to an extent not causing environmental problems, and is condensed and scrubbed. A part of the generated steam is released to the environment, and the pressure of the condensate storage tank 10 is lowered to maintain the condensation and scrubbing ability.

Although FIGS. 7 and 8 show a conventional example of the condensate storage facility for one reactor, FIG. 7 and FIG. Each of the condensate storage facilities shown in FIG. 8 is provided.

[0011]

It is desirable that the above-mentioned condensate storage facility has a small capacity from the viewpoint of the location of the nuclear power plant and the construction cost, while securing a large capacity from the viewpoint of further improving safety. Is desirable.

As a balance of such opposing conditions, conventionally, the capacity of the emergency water source 14 for about 8 hours has been secured. However, in the unlikely event that SBO occurs and if it lasts for a long time, if the amount of water for 8 hours is consumed, the injection means will be lost, and eventually core damage may occur.

In order to ensure the long-term safety of the nuclear power plant even after the occurrence of the above SBO, it is effective to maintain the plant proof stress after the occurrence of the event for as long as possible. If this becomes possible, there will be a time margin for external rescue, and recovery after core cooling and evacuation activities will become easier.

For this purpose, it is desirable to increase the water source of the condensate storage facility and prolong the time until the core is damaged.
Simply increasing the amount of water will increase the capacity of the condensate storage facility,
It is difficult in terms of location and economically unfavorable.

The present invention has been made in view of the above conventional circumstances, and an object thereof is to make it possible to significantly extend the time for which the plant proof stress is maintained even when SBO occurs, while at the same time being advantageous in terms of location and economy. It also provides an excellent condensate storage facility.

[0016]

In order to achieve the above object, the condensate storage facility according to claim 1 of the present invention is
In the condensate storage facility shared by the two nuclear reactors, the common water source part that is shared by the two nuclear reactors and used during normal operation ,
And the core injection water source at the time of all AC power loss event
Accident where a water source part for all AC power loss events shared by the two reactors and the two reactors below were independently installed
The emergency water source used to inject water into the reactor core at that time .

The condensate storage facility according to a second aspect is the first aspect.
In the condensate storage facility described, a filter vent water source that is installed separated by a partition wall to reduce the pressure and radioactive materials in the reactor at the time of a severe event, and the steam in the reactor is guided and condensed to reduce the pressure in the reactor. It has the suppression pool of each of the two nuclear reactors to be reduced and at least one vent pipe connected to the filter vent water source.

The condensate storage facility according to a third aspect is the second aspect.
In the condensate storage facility described above, the vent pipe is branched and has a bypass pipe connected to an exhaust pipe for diluting and discharging the gas radioactive waste.

A condensate storage facility according to a fourth aspect is the first aspect.
Alternatively, in the condensate storage facility according to the item 2, there is provided a partition wall which is provided inside from a bottom portion to a ceiling portion and has at least one through hole above an upper end portion of the emergency water source portion.

The condensate storage facility according to claim 5 is characterized in that
Or the condensate storage facility according to 3, further comprising a partition wall provided inside from a bottom portion to a ceiling portion and having at least one through hole above an upper end portion of the emergency water source portion, and the filter vent water source is the partition wall. Installed on both sides of the wall
And each of the vent pipes is on both sides of the partition wall.
The filter vent water source is connected .

The condensate storage facility according to claim 6 is the same as that according to claim 2.
In the condensate storage facility described, the filter vent water source is connected to an injection pipe provided from outside the reactor containment vessel via an isolation valve.

In the condensate storage facility of the above structure, in the invention according to claim 1, the common water source is shared between the two nuclear power plants, so that the condensate storage tank is installed independently as compared with the case where the condensate storage tank is independently installed. By reducing the total capacity and sharing the reduced amount as a core injection water source during SBO,
The plant yield capacity can be improved without increasing the total capacity.

According to the second aspect of the present invention, the steam from the gas phase portion of the suppression pool is guided from the vent pipe to the filter vent water source to be condensed, and at the same time, the radioactive substance contained in the steam is scrubbed.

According to the third aspect of the invention, the vapor from the gas phase portion of the suppression pool is selectively discharged to the filter vent water source and the exhaust stack. According to the invention of claim 4,
While improving the structural strength of the condensate storage facility, maintain the common use of water sources for normal and severe events and the independence of emergency water sources.

According to the invention of claim 5, the filter vent water source separated by the partition wall is shared by two reactors. In the invention according to claim 6, it becomes possible to supply the external water from the outside of the reactor containment vessel to the filter vent water source through the injection pipe.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a condensate storage facility according to the present invention will be described below.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the condensate storage facility according to the present invention will be described below with reference to FIG. Condensate storage tank 10a has 2
The basic nuclear power plant, for example, Units A and B, is a tank with an integrated structure that is shared by Units A and B, and is installed in the reactor building or the like.

Two partition walls 17 are installed in the lower part, whereby a unit A emergency water source 14a and a unit B emergency water source 14 are provided.
Filter vent water source 1 for both b and A / B
It is divided into 6. A water source for all AC power loss events (hereinafter referred to as SBO water source) 18 is secured above this unit as a water source for severe events common to Units A and B, and a common water source shared by Units A and B is further above it. 13 is secured.

In the filter vent water source 16, an S
When BO occurs, filter vent pipes 15a and 15b for guiding the steam vented from the vapor phase part (not shown) of the suppression pools of Units A and B are installed separately in Units A and B. . The lower ends of the filter vent pipes 15a and 15b are opened and are submerged in the filter vent water source 16, and it is desirable to secure a submerged depth of about 5 m as a depth required for vapor condensation. .

In this embodiment, two condensate storage tanks 10a are commonly used.
Therefore, the regular water source 13 can be rationalized, and as a result, the SBO water source 18 can be secured with the same total capacity. By combining this water source with the Unit A emergency water source 14a or the Unit B emergency water source 14b provided independently in Units A and B, it is possible to inject water into the core for a long time.

Next, a second embodiment of the present invention will be described with reference to FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description of the configuration will be omitted. Figure 2
Shows the configuration including the reactor 2, and the configuration inside the condensate storage tank 10a is the same as that of the first embodiment.

In this embodiment, the bypass pipe 22 connected to the exhaust pipe 21 is branched from the vent pipe 31 provided from the suppression pool 7. Also,
The vent pipe 31 is provided with a stop valve 32a upstream of the connection point of the bypass pipe 22, and the vent pipe 15a connected to the filter vent water source 16 is also provided with a stop valve 32b upstream of the bypass pipe 22. .

In the condensate storage facility constructed as described above, the vapor discharged from the suppression pool 7 can be directly guided to the exhaust pipe 21. Also, stop valve 3
By opening and closing 2a and 32b, it is possible to release the steam selectively as the steam discharged to the exhaust stack 21 or as the steam guided to the filter vent water source 16, or at the same time.

No core damage occurred during SBO,
The steam discharged to the suppression pool 7 contains almost no radioactive substances such as iodine, like the steam during normal operation. Therefore, it is easier to ensure the integrity of the core by avoiding the temperature rise in the condensate storage tank 10a and injecting the low temperature water into the core, rather than by introducing the steam into the condensate storage tank 10a and cooling it. Therefore, the steam is directly guided to the exhaust stack 21 and discharged. This makes it possible to further enhance and improve the plant proof stress during SBO.

Next, a third embodiment of the condensate storage facility according to the present invention will be described with reference to FIG. In FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description of the configuration will be omitted. In this embodiment, in addition to the first embodiment, a partition wall 20 is additionally provided in the central portion of the condensate storage tank 10a. When two condensate storage tanks 10a are shared, it is considered that the condensate storage tanks 10a will be installed in the middle part of the two nuclear power plants, and the earthquake resistant walls that receive horizontal force during an earthquake will be evenly distributed over the building. Since it is desirable to place it, it may be placed in the center of the building. Therefore, depending on the layout plan, it is possible that the originally required earthquake-resistant wall cannot be installed in the area of the condensate storage tank 10a.

In the present embodiment, such a case is taken into consideration, and the partition wall 20 is installed in the central portion of the condensate storage tank 10a. The partition wall 20 is utilized as an earthquake resistant wall by ensuring a sufficient wall thickness. The partition wall 20 is provided with at least one through hole 19 above the Unit A emergency water source 14a and the Unit B emergency water source 14b, and the SBO water source 18 and the regular water source 13 can be shared by two nuclear power plants. However, the filter vent water source 16
a and 16b are installed independently for each nuclear power plant. Therefore, although this filter vent water source is independently provided, the overall volume increases as the amount of water increases, but it is possible to secure the partition wall 20 that can be an earthquake resistant wall inside, and the structural strength is improved. It is easy to deal with and can improve the earthquake resistance.

Next, a fourth embodiment of the condensate storage facility according to the present invention will be described with reference to FIG. In FIG. 4, the same parts as those in FIG. In FIG. 4, similarly to the third embodiment of the present invention, the partition wall 17 having the through hole 19 is installed, but the filter vent pipe 15 utilizes the through hole 19 and the partition wall via the communication pipe 26. It is connected to filter vent water sources 16a and 16b provided on both sides of 17.

In the case of this embodiment having the above-mentioned structure, the filter vent water sources 16a and 16b can be used for both the nuclear power plant and the condensate storage tank 10a.
It is possible to improve the earthquake resistance because it is easy to deal with the building structure plan without increasing the capacity.

Finally, a fifth embodiment according to the present invention will be described with reference to FIG. In FIG. 5, the reactor building 3
0 is buried underground. The condensate storage tank 10a has the same configuration as that of the first embodiment, but the injection pipe 23 is connected to the condensate storage tank 10a via the isolation valve 25 and the injection port 27 provided on the ground.

The other embodiment provides the condensate storage tank 10a having a long-time core injection capacity. However, in this embodiment, the isolation valve 25 is used even if the water source for core injection is lost after a predetermined time has elapsed. And the water is injected through the injection port 27 on the ground, it becomes possible to secure a water source for cooling the core in the condensate storage tank 10a. In this embodiment, water is poured into the condensate storage tank 10a by gravity drop, and therefore, it is possible to cope with SBO. By providing the filter vent pipe 15 for connecting the suppression pool 7 and the filter vent water source 16 as seen in the conventional example, and installing the discharge pipe 24 for connecting the space portion of the condensate storage tank 10a to the exhaust pipe 21,
From the core to the suppression pool 7, condensate storage tank 10a,
Since a heat removal path leading to the exhaust stack 21 can be formed, while a water injection function by gravity fall can be secured, a static core cooling function that does not rely on power as a whole can be achieved, and safety at SBO is dramatically improved. Can be improved.

The present embodiment is not limited to the case where the condensate storage tank 10a is installed inside the reactor building, and the condensate storage tank 10a is not limited to this.
It is effective when is installed at a position where water can be poured by gravity.

Further, each of the embodiments described above can be applied to an outdoor tank type condensate storage tank as seen in the conventional example. Furthermore, it is desirable that the drive source of water to be injected is gravity, which is static, but it goes without saying that water may be injected by driving a pump by a diesel generator having a predetermined reliability.

[0043]

As described above, in the condensate storage facility of the present invention, even when all AC power is lost, the core soundness is significantly improved from the conventional one, and at the same time the location and economy of the nuclear power plant are improved. Can also be achieved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a condensate storage facility according to the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the condensate storage facility according to the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of a condensate storage facility according to the present invention.

FIG. 4 is a configuration diagram showing a fourth embodiment of the condensate storage facility according to the present invention.

FIG. 5 is a configuration diagram showing a fifth embodiment of the condensate storage facility according to the present invention.

FIG. 6 is a configuration diagram around a nuclear reactor for explaining an all-AC power loss event.

FIG. 7 is a block diagram showing a conventional example of a condensate storage facility.

FIG. 8 is a configuration diagram showing a conventional example of a condensate storage facility.

[Explanation of symbols]

1 ... Reactor containment vessel 2 ... Reactor 3 ... Core 4 ... Relief safety valve 5 ... Main steam isolation valve 6 ... Main steam piping 7 ... Suppression pool 8 ... Exhaust pipe 9 ... Reactor isolation cooling system 10, 10a ... Condensate Storage tank 11 ... Regular water source nozzle 12 ... Emergency water source nozzle 13 ... Regular water source 14a, 14b ... Emergency water source 15, 15b, 15b ... Filter vent piping 16, 16a, 16b ... Filter vent water source 17 ... Partition wall 18 ... All AC power source Loss event response water source 19 ... Opening 20 ... Partition wall 21 ... Exhaust pipe 22 ... Bypass pipe 23 ... Injection pipe 24 ... Discharge pipe 25 ... Isolation valve 26 ... Branch pipe 27 ... Injection port 30 ... Reactor building 31 ... Piping 32a, 32b … Stop valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI G21D 3/04 G21C 9/00 GDBA (72) Inventor Yutaka Muramatsu 1-1-1 Shibaura, Minato-ku, Tokyo Toshiba Headquarters (72) Inventor Masahiro Tsutagawa 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Toshiba Yokohama Works, Inc. ) Reference JP-A 1-267498 (JP, A) JP-A-3-77095 (JP, A) JP-A-4-344495 (JP, A) JP-A-6-230166 (JP, A) JP-A-6-230166 (JP, A) 9-61577 (JP, A) JP 62-263499 (JP, A) JP 63-215999 (JP, A) JP 63-282698 (JP, A) JP 58-39995 (JP, A) (58) Fields surveyed (In t.Cl. ⁷ , DB name) G21D 1/00 GDB G21C 9/004 GDB G21C 15/18 GDB G21D 1/02 GDB G21D 3/04 GDB

Claims (6)

(57) [Claims] 1. In a condensate storage facility shared by two nuclear reactors, a common water source part shared by the two nuclear reactors and used during normal operation , and core injection water at the time of a loss of all AC power sources.
Loss of all AC power source that is the source of power and is shared by the two reactors
A condensate storage facility comprising an elephant-corresponding water source part and an emergency water source part provided below the two reactors independently of each other for injecting water into the core in the event of an accident . 2. A filter vent water source provided separately by a partition wall for reducing the pressure and radioactive substances in the reactor at the time of a severe event, and a vapor for guiding and condensing steam in the reactor to reduce the pressure in the reactor. The condensate storage facility according to claim 1, further comprising: a suppression pipe of each of two reactors and at least one vent pipe that connects the filter vent water source. 3. The condensate storage device according to claim 2, wherein the vent pipe has a branched bypass pipe connected to an exhaust stack for diluting and discharging the gas radioactive waste. 4. The condensate according to claim 1, further comprising a partition wall provided inside from the bottom to the ceiling and having at least one through hole above the upper end of the emergency water source. Storage equipment. 5. A filter vent which is provided inside from a bottom portion to a ceiling portion and has a partition wall having at least one through hole above an upper end portion of the emergency water source portion.
Water sources are provided on both sides of the partition and each of the beds is
The inlet pipe is the filter vent water on both sides of the partition wall.
Condensate storage facility according to claim 2 or 3, characterized in that it is connected to a source . 6. The condensate storage facility according to claim 2, wherein the filter vent water source is connected to an injection pipe provided from the outside of the reactor containment vessel through an isolation valve.