JPH0452430B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a cleanliness maintenance device for a pressure suppression chamber,
In particular, the present invention relates to a pressure suppression chamber cleanliness maintenance device that improves the quality of pool water in the pressure suppression chamber and the decontamination of the inner wall of the pressure suppression chamber.

[Technical background of the invention and its problems]

Boiling water nuclear power plants generally have a pressure suppression chamber. This pressure suppression chamber consists of a steam condensing tank into which high-temperature, high-pressure steam in the reactor pressure vessel and reactor containment vessel flows and condenses the steam, and also serves as a water source for the emergency core cooling system. In addition, in the event of an emergency such as a rupture of the primary system piping, the pool water stored in the pressure suppression chamber is injected into the reactor pressure vessel and used to re-flood the reactor core and cool it.
Tests to confirm the integrity of this emergency core cooling system are conducted as appropriate during operation and shutdown of the reactor, and steam is repeatedly brought in and out of the pressure suppression chamber. Furthermore, if the reactor pressure rises excessively during reactor startup/shutdown operations, high-pressure steam also flows into the pressure suppression chamber. This inflowing steam causes a large amount of activated corrosion products to flow into the pressure suppression chamber. This corrosion product increases year by year as the reactor operates, and is deposited at the bottom of the pressure suppression chamber after being left unused for a long time. Contamination of the pressure suppression chamber may impair the function and integrity of various equipment that uses the pool water as a water source, such as the emergency core cooling system. Therefore, purification of pool water was desired. In addition, when the inner walls of the pressure suppression chamber are repaired or repainted, decontamination work is carried out in advance.
Contamination of the inner walls requires a great deal of labor and time, and the pressure suppression chamber must be cleaned in order to reduce radiation exposure to workers engaged in decontamination work and to shorten the construction period for repairing the inner walls. It has long been strongly desired.

[Purpose of the invention]

The present invention was made in view of the above-mentioned circumstances, and it purifies the water quality of the pool water in the pressure suppression chamber, and also purifies the pressure suppression chamber to improve the reliability and soundness of the reactor system. An object of the present invention is to provide a cleanliness maintenance device for a pressure suppression chamber that can improve the efficiency of decontamination work.

[Summary of the invention]

In order to achieve the above object, the present invention is configured as follows.

In a boiling water reactor having a pressure suppression chamber, a blower is provided in the air supply piping that communicates the space of the pressure suppression chamber with the water in the pool, and a submerged portion of the air supply piping is submerged in the pool water. A branch pipe for blowing disposed around the entire bottom of the pressure suppression chamber is connected to the branch pipe for blowing out, and a large number of blowing holes are formed in the axial direction of the branch pipe for blowing toward the bottom of the pressure suppression chamber. The circulation piping that circulates the pool water in the chamber to the pressure suppression chamber is provided with a pump for forced circulation of the pool water and a filtration desalination device that purifies the quality of the pool water.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pressure suppression chamber cleanliness maintenance device according to the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram showing the configuration when the present invention is applied to a boiling water reactor mark type, and the reference numeral 1 in the figure is a reactor containment vessel housed in a reactor building (not shown). . A reactor pressure vessel 2 is housed within the reactor containment vessel 1, and a pressure suppression chamber 3 is arranged below the reactor pressure vessel 2. Pool water 4 is stored in this pressure suppression chamber 3, and the surface of this pool water 4 is partitioned off by a diaphragm floor 5 with a space 3a in between. This diaphragm floor 5 has the reactor containment 1
An appropriate number of vent pipes 6 are installed to guide reactor water and the like flowing into the pressure suppression chamber 3. This pressure suppression chamber 3 is provided with a cleanliness maintenance device, which includes a stirring device that stirs the pool water 4 in the pressure suppression chamber 3, and a stirring device that purifies the quality of the pool water in the pressure suppression chamber 3. It mainly consists of a purification device. The stirring device is configured as follows, for example.

First, an air supply pipe 7 is provided which communicates the pool water 4 of the pressure suppression chamber 3 with the space 3a thereof. As shown in FIG. 1, the intermediate portion of the air supply pipe 7 is disposed outside the reactor containment vessel 1, and a blower 8 is interposed therebetween. On the other hand, the submerged end of the air supply pipe 7 extending into the pool water 4 of the pressure suppression chamber branches into a number of branch pipes 9 for blowing out, and these branch pipes 9 for blowing out have their pipe axes as shown in FIG. A large number of blow-off holes 10 are arranged in a row in the direction. These blowout branch pipes 9 are arranged at the bottom of the pressure suppression chamber 3 or near the bottom or near the inner wall, and are provided around the entire circumference of the annular pressure suppression chamber 3.

Further, a blowout hole 10 provided in the blowout branch pipe 9
is opened toward the inner bottom of the pressure suppression chamber 3, and the outlet branch pipe 9 disposed near the inner wall of the pressure suppression chamber 3 is opened toward the inner wall thereof, and is opened toward the inner bottom of the pressure suppression chamber 3. The structure is designed to facilitate the removal of corrosion products, etc. attached to the

On the other hand, the purifying device is configured as follows, for example.

The pool water 4 of this pressure suppression chamber 3 is transferred to the pressure suppression chamber 3.
A circulation pipe 11 is provided to circulate the water. The pool water 4 suction port of this circulation pipe 11 opens at the lower part of the pressure suppression chamber 3, and the discharge port of the circulation pipe 11 is arranged above the above-mentioned suction port. A circulation pump 12 and a filtration/desalination device 13 are sequentially installed in this circulation pipe 11 from its suction port to its discharge port.

Next, the operation of the embodiment of the present invention described above will be described.

First, when the blower 8 is started, gas such as nitrogen, air, etc. in the space 3a of the pressure suppression chamber 3 is sucked in and supplied to the blowout branch pipe 9 via the air supply pipe 7. It is blown out from the blow-off hole 10 into the pool water 4 of the pressure suppression chamber 3. When this gas such as air is blown out from the blowout branch pipe 9 disposed in the pool water 4, the corrosion products precipitated and deposited at the bottom of the pressure suppression chamber 3 rise upward to the pool water 4. A water flow is generated, and the pool water 4 is stirred together with the corrosion products floating on the surface of the pool water 4. During this stirring, corrosion products adhering to the inner wall of the pressure suppression chamber 3 also fall into the pool water 4. Since the blowout branch pipe 9 is disposed around almost the entire circumference of the pressure suppression chamber 3, the pool water 4 is stirred almost all around the pressure suppression chamber 3. When the circulation pump 12 is driven during such agitation of the pool water 4, the pool water 4 is sucked through the suction port of the circulation pipe 11. When the pool water 4 is being sucked in, the pool water 4 has already been stirred as described above, so it settles and accumulates at the bottom of the pressure suppression chamber 3, and is sucked in together with the corrosion products attached to the inner wall thereof. This suction water is sent to a filtration and demineralization device 13 by the circulation pump 2, where foreign substances such as the corrosion products are filtered out and the water quality is purified. The pool water 4 whose water quality has been purified by the filtration and demineralization device 13 is injected into the pressure suppression chamber 3 from the outlet of the circulation pipe 11. Therefore, the blower 7 and the circulation pump 1
When the second class is operated for a predetermined period of time, corrosion products that are precipitated and deposited on the inner bottom of the pressure suppression chamber 3 and attached to the inner wall are filtered by the filtration desalination device 13, and the quality of the pool water 4 is purified. At the same time, the inner wall of the pressure suppression chamber 3 is cleaned.

Next, another embodiment in which the present invention is applied to a boiling water reactor mark type will be described with reference to FIG.

In the boiling water reactor mark type, pressure suppression chamber 20
has a torus-like shape as shown in Figure 3,
They are arranged in a ring shape around the lower outer periphery of the reactor containment vessel 1. Further, in this embodiment, each component of the purification device, for example, the circulation pump 12 is a residual heat removal system, such as an injection pump 21 for injecting reactor water, and the filtration desalination device 13 is a filtration desalination device 22 of a condensate purification system. The configuration is such that they are shared by each. In this embodiment, the configuration of the stirring device is almost the same as that of the first embodiment described above, so the explanation thereof will be omitted.

The residual heat removal system described above removes the residual heat inside the reactor after the reactor operation is stopped, and is installed in the pressure suppression chamber 2.
An appropriate number of injection pumps 21 are provided for injecting the pool water 4 in the reactor into the reactor. The condensate purification system purifies the water quality of condensate and supplies it to the nuclear reactor, and is equipped with an appropriate number of filtration and desalination devices 22. Accordingly, as shown in FIG.
3, an inlet side connecting pipe 24 is connected to the inlet side connecting pipe 24 so as to branch from this suction pipe 23 on the discharge side of the water injection pump 21. The other end of this inlet side connecting pipe 24 is connected to the inlet side of the filtration desalination device 22 of the above-mentioned condensate purification system. An outlet side connecting pipe 25 is connected to the outlet side of the filtration and demineralization device 22 . The other end of this outlet side connecting pipe 25 is connected to the middle of the return pipe 26 of the residual heat removal system to form one closed loop, and the pressure suppression chamber 20
pool water is forced to circulate through this closed loop. An inlet valve 27 and an outlet valve 28 are provided in the inlet and outlet connecting pipes 24 and 25, respectively. In addition, the piping of the residual heat removal system and the condensate purification system connected to the inlet side connecting pipe 24 and the outlet side connecting pipe 25, respectively, is provided on the upstream side from the connection point with the inlet side and outlet side connecting pipes 24, 25. Alternatively, stop valves 29, 30, 31, 32 are installed on the downstream side, and these stop valves 29, 30, 31, 3
2 are all closed, all of the pool water 4 sucked in by the injection pump 21 flows through the filtration desalination device 22, and is configured so as not to flow out to the residual heat removal system and condensate purification system.

That is, the pressure suppression chamber 20, the injection pump 21, the filtration desalination device 22, and the piping that connects these to each other constitute one closed loop, and the pool water 4 in the pressure suppression chamber 20 sucked by the injection pump 21 is It is designed to circulate in this closed loop.

Therefore, when the blower 8 on the stirring device side is started, gas such as air that has flowed into the space 3a of the pressure suppression chamber 20 in the same manner as in the first embodiment described above flows through the air supply pipe 7 to the pool water. The air is supplied to a branch pipe 9 for blowing disposed in the pipe 4. This gas such as air is further blown out into the pool water 4 from the blow-off hole 10 of the blow-off branch pipe 9, stirs the pool water 4, and settles and accumulates on the inner bottom of the pressure suppression chamber 20, or Corrosion products adhering to the inner wall are blown up into the pool water 4 to generate a water flow and stir it. At the same time, when the injection pump 21 on the purification device side is started, the injection pump 21 sucks the pool water 4 being stirred together with the corrosion products and transports this suction water to the filtration and demineralization device 22 . At this time, stop valves 29, 30, 3 installed in the residual heat removal system and condensate purification system
1 and 32 are all closed, and the inlet valve 27 and outlet valve 28 of the inlet and outlet side connecting pipes 24 and 25 are open. Therefore, all of the above-mentioned suction water flows into the filtration and demineralization device 22, where it is subjected to filtration and demineralization treatment to remove foreign substances such as corrosion products, purify the water quality, and discharge it from the filtration and demineralization device 22. . The purified water is returned to the pressure suppression chamber 20 via the return pipe 26. As a result, the inside of the pressure suppression chamber 20 is maintained clean.

Note that the same or equivalent parts in FIG. 3 as in FIG. 1 are given the same reference numerals and their explanations are omitted.

〔Effect of the invention〕

As explained above, the present invention is configured to agitate the pool water in the pressure suppression chamber, purify the pool water, and simultaneously clean the pressure suppression chamber, so that corrosion products in the pressure suppression chamber are removed. The cleanliness of pool water can be maintained at all times by preventing the accumulation and adhesion of water. As a result, the health and reliability of nuclear reactor system equipment and equipment as fluid equipment can be improved. Furthermore, since the pump for the residual heat removal system, the filtration desalination device for the condensate purification system, etc. can be shared, the above-mentioned effects can be achieved at low cost. In addition, since the pressure suppression chamber can be kept clean at all times, it is possible to improve the decontamination of the pressure suppression chamber during repainting work, etc., reduce work time, and reduce worker exposure to radiation during the work. Radiation can be reduced. Furthermore, since the gas released into the pool water is the gas in the pressure suppression chamber, the amount of radioactive gas waste can be minimized. Further, since the blowout branch pipe is disposed around the entire bottom of the pressure suppression chamber and the blowout hole is directed toward the bottom, the entire pool can be efficiently agitated with a small amount of released gas. Furthermore, since the blow-off holes are directed toward the bottom, corrosion products can accumulate in the blow-off holes and block them.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram for explaining the configuration of one embodiment of the present invention, Fig. 2 is an enlarged perspective view of a part of the branch pipe for blowing out the same, and Fig. 3 is the whole of another embodiment of the same. FIG. 1... Reactor containment vessel, 2... Reactor pressure vessel, 3, 20... Pressure suppression chamber, 4... Pool water,
7...Air supply piping, 8...Blower, 9...Blowout branch pipe, 10...Blowout hole, 11...Circulation pipe,
12... Circulation pump, 13, 22... Filtration desalination device, 21... Injection pump, 24... Inlet side connection pipe, 25... Outlet side connection pipe, 29, 30, 31,
32...stop valve.

Claims (1)

[Scope of Claims] 1. In a boiling water reactor equipped with a pressure suppression chamber, a blower is provided in the air supply piping that communicates the space of the pressure suppression chamber with the pool water, and the air supply piping is provided with a blower. A branch pipe for blowing out that is arranged around the entire bottom of the pressure suppression chamber is connected to the submerged part of the pool that is submerged in water, and a large number of blowing holes are installed in the axial direction of the branch pipe for blowing out at the bottom of the pressure suppression chamber. On the other hand, a pump for forced circulation of pool water and a filtration desalination device for purifying the quality of pool water are installed in the circulation piping that circulates pool water from the pressure suppression chamber to this pressure suppression chamber. A pressure suppression chamber cleanliness maintenance device characterized by: 2. The cleanliness maintenance device for a pressure suppression chamber according to claim 1, wherein the pump for forced circulation of pool water is a pump for transporting pool water of a residual heat removal system. 3. The cleanliness maintenance device for a pressure suppression chamber according to claim 1, wherein the filtration and desalination device is a filtration and desalination device of a condensate purification system.