JPH0545999Y2 - - Google Patents

Description

[Detailed description of the invention] "Field of industrial application" This invention relates to a pedestal in a nuclear reactor containment vessel.

``Prior Art'' Until now, as a reactor containment vessel for a boiling water reactor, the inside of the containment vessel was divided into upper and lower sections by a diaphragm floor that crossed the inside of the containment vessel body. A suppression chamber is defined, and the reactor pressure vessel accommodated in the dry well is supported by a pedestal rising from the bottom of the containment vessel body and penetrating the suppression chamber. something is being developed.

The suppression chamber stores a predetermined amount of water, and when water vapor leaks into the dry well, the water vapor is quickly condensed by the stored water and the pressure inside the dry well increases. In the reactor containment vessel of the type mentioned above, a large number of vent pipes are generally provided to penetrate the diaphragm floor, and the upper ends of these vent pipes are opened into the dry well, and the vent pipes are By opening the lower end of the tube into the water in the suppression chamber, water vapor leaking into the drywell is directed into the stored water.

``Problems that the invention seeks to solve'' However, in conventional reactor containment vessels in which a large number of vent pipes are installed through the diaphragm floor, suppression is not possible due to the vent pipes and the support mechanism that supports the vent pipes. There was a problem that the chamber was crowded.

This invention was made to solve the above-mentioned problem, and the containment vessel main body is divided into upper and lower sections by a diaphragm floor that crosses the containment vessel main body, and a dry well and a suppression chamber are defined. In a reactor containment vessel of the type in which the reactor pressure vessel housed in the dry well is supported by a pedestal rising from the bottom of the containment vessel body and penetrating the suppression chamber, the diaphragm floor It is an object of the present invention to provide a pedestal that can avoid congestion in a suppression chamber while ensuring a desired pressure suppression effect without having to pass through a large number of vent pipes.

"Means for Solving the Problems" The pedestal in the reactor containment vessel according to this invention is divided into an upper and lower part by a diaphragm floor that crosses the containment vessel body, and a dry well and a supplement. A nuclear reactor of a type in which a suppression chamber is defined, and a reactor pressure vessel housed in the dry well is supported by a pedestal that rises from the bottom of the containment vessel body and penetrates the suppression chamber. In the pedestal of the containment vessel, a hollow portion is provided in the cylindrical peripheral wall to communicate the dry well and the suppression chamber, and the peripheral wall is lower than the water level of the stored water in the suppression chamber. A communication passage that communicates the hollow part with the gas phase part in the suppression chamber is formed at an upper position along the horizontal radial direction, and a communication passage in the dry well is formed at an inner position in this communication passage. A structure is adopted in which a vacuum breaker valve that opens a communication passage when the pressure in the suppression chamber becomes lower than the pressure in the suppression chamber by a predetermined amount is provided in an exposed state in the hollow portion.

"Operation" In the pedestal in the reactor containment vessel according to this invention, the dry well and the gas phase part of the suppression chamber are connected in the horizontal radial direction via the hollow part provided in the peripheral wall and the communication passage. Connected.

Since these hollow parts and communication passages function as vent pipes, they are installed to avoid congestion in the suppression chamber without penetrating the diaphragm floor vertically.

The vacuum breaker valve is provided inwardly in the communication path and exposed in the hollow part, so that it is separated from the gas phase part of the dry well and suppression chamber to avoid interference therewith. .

When the internal pressure of the dry well is lower than the pressure of the gas phase portion of the suppression chamber by a predetermined amount, the pressure is brought to an equilibrium state by opening the communication passage.

“Embodiment” An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows a reactor containment vessel of a boiling water reactor in which an embodiment of the present invention is used.

This reactor containment vessel 1 has a containment vessel main body 2 divided vertically by a diaphragm floor 3 that crosses the inside of the containment vessel main body 2, and a dry well 4 and a suppression chamber 5 are defined. A reactor pressure vessel 6 housed in the dry well 4 is supported by a pedestal 7 that rises from the bottom of the containment vessel body 2 and penetrates a suppression chamber 5. The reactor containment vessel 1 has been improved to be more compact, and the containment vessel body 2 has a structure in which the inside of a reinforced concrete vessel is covered with a steel liner. In addition to ensuring mechanical strength, the steel liner ensures airtightness and watertightness.

The pedestal 7 has a substantially cylindrical peripheral wall 7.
a is provided with a hollow portion 9 that communicates the dry well 4 and the suppression chamber 5, and the water surface position of the water (reserved water) W stored in the suppression chamber 5 at the upper part of the peripheral wall 7a. At a position above H, a communication passage 10 is formed to communicate the hollow part 9 and the gas phase part 5a in the suppression chamber 5.

A dry well 4 is provided in the communication path 10.
A vacuum breaker valve 11 is provided which opens the communication passage 10 when the pressure inside the suppression chamber 5 drops by a predetermined amount from the pressure inside the suppression chamber 5.

Details of this pedestal 7 are shown in Figures 2 and 3.
As shown in the figure.

That is, the inside of the cylindrical peripheral wall 7a is a lower dry well 12 connected to the above-mentioned dry well 4, and the inner peripheral surface of this peripheral wall 7a is
As shown in FIG. 2, a pressure vessel support portion 7b that supports the skirt portion 6a of the reactor pressure vessel 6 is provided.

Further, as shown in Fig. 3, the peripheral wall 7a has a structure in which unit walls made of reinforced concrete surrounded by steel plates are layered concentrically in triple layers in the radial direction, and divided into 20 equal parts in the circumferential direction. The structure is divided into:

The hollow portions 9 are formed by utilizing a radially intermediate layer of the peripheral wall 7a, and are provided at 10 locations on the entire peripheral wall.

The communication passages 10 formed in these hollow portions 9 are formed by embedding straight pipes 14 in the radially outermost layer of the peripheral wall 7a, as shown in FIGS. 3 and 4. The vacuum breaker valve 11 is attached to the hollow portion 9 side of the communication path 10.

As shown in FIG. 4, the vacuum breaker valve 11 has a base 11a, which serves as a valve seat, which is fixed to the inner steel plate of the outermost layer of the peripheral wall 7a, and an arm 1 is attached to the base 11a.
1b is pin-coupled so as to be rotatable in a vertical plane, and a valve body 11c is provided at the tip of this arm 11b. From the above structure, the valve body 11c can be opened and closed in the hollow part 9 as shown by arrow A, and when the air pressure on the dry well 4 side is lower than the air pressure inside the suppression chamber 5 by a predetermined amount. It is set to open toward the hollow part 9 side by the differential pressure.

In addition, in this embodiment, a ladder 15 descends inside the hollow part 9 for maintenance of the vacuum breaker valve 11, etc.
(See Figure 1).

In the reactor containment vessel 1 as described above, the hollow portion 9 provided in the peripheral wall 7a of the pedestal 7 functions as a vent pipe that communicates the dry well 4 and the suppression chamber 5. There is no need to penetrate the diaphragm floor 3 with the vent pipe, and congestion in the suppression chamber 5 can be avoided. Further, in this pedestal 7, a communication passage 10 is provided on the upper peripheral wall of the pedestal 7, which communicates the hollow part 9 with the gas phase part 5a in the suppression chamber 5. Since a vacuum breaker valve 11 is provided which opens the communication passage 10 when the pressure in the suppression chamber 5 drops by a predetermined amount, the water vapor leaking into the dry well 4 condenses in a short period of time and suppresses the suppression chamber. If the air pressure in the dry well 4 becomes negative relative to the air pressure in the suppression chamber 5, the gas phase portion 5a of the suppression chamber 5 is immediately communicated with the dry well 4 to reduce the pressure. It is possible to achieve equilibrium and prevent adverse effects caused by pressure imbalance.

As described above, according to the pedestal 7, there is no need to pass a large number of vent pipes through the diaphragm floor 3, and it is possible to avoid crowding in the suppression chamber 5 while ensuring the desired pressure suppression effect. .

In addition, in the pedestal 7 of the above embodiment,
A ladder 15 is provided in the hollow part 9, and since the vacuum breaker valve 11 opens toward the hollow part 9, inspection and maintenance of the valve body 11c, etc. of the vacuum breaker valve 11 cannot be carried out from the hollow part 9.
It can be easily done from

"Effects of the invention" As is clear from the above explanation, according to the pedestal in the reactor containment vessel according to this invention,
It has the following effects.

(1) The peripheral wall of the pedestal is provided with a hollow part that communicates with the dry well and the suppression chamber, and a communication passage that communicates the hollow part with the gas phase part in the suppression chamber. Since the vacuum breaker valve is installed in an exposed position in the hollow part of the passage, it is possible to prevent the occurrence of adverse effects due to the pressure imbalance phenomenon based on the operation of the vacuum breaker valve. In addition, the installation of a vent pipe in the suppression chamber can be omitted, thereby avoiding congestion due to the installation of the vent pipe.

(2) The vacuum breaker valve is located inward in the communication path,
By being exposed in the hollow part, it can be separated from the gas phase part of the dry well and suppression chamber to avoid interference with them, and maintenance and inspection of the vacuum breaker valve can be performed from the hollow part of the pedestal. etc. can be carried out.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a boiling water reactor equipped with an embodiment of the pedestal in the reactor containment vessel according to this invention, Fig. 2 is an enlarged view of the main part of the pedestal shown in Fig. 1, and Fig. 3 The figure is in Fig. 2 -
4 is an enlarged view of the portion indicated by the reference numeral in FIG. 2. 1... Reactor containment vessel, 2... Containment vessel body,
3...Diaphragm floor, 4...Dry well, 5...Suppression chamber, 5a...Gas phase section, 6...Reactor pressure vessel, 7...Pedestal, 7a...Peripheral wall, 9...Hollow Part, W...Reserved water, 10...Communication path, 11...Vacuum breaker valve, 14
……Straight pipe.

Claims (1)

[Scope of utility model registration request] The inside of the containment vessel body 2 is vertically divided by a diaphragm floor 3 that crosses the inside of the containment vessel body to define a dry well 4 and a suppression chamber 5, and the atoms contained in the dry well are In a reactor containment vessel in which the reactor pressure vessel 6 is supported by a pedestal 7 rising from the bottom of the containment vessel body and penetrating the suppression chamber, the pedestal is a cylindrical peripheral wall 7a. A hollow portion 9 is provided that communicates the dry well and the suppression chamber, and the water stored in the suppression chamber of the peripheral wall W is provided.
A communication passage 10 that communicates the hollow part with the gas phase part 5a in the suppression chamber is formed along the horizontal radial direction at a position above the water surface of the suppression chamber. A nuclear reactor containment vessel characterized in that a vacuum breaker valve 11 that opens a communication passage when the air pressure in the dry well decreases by a predetermined amount than the air pressure in the suppression chamber is provided in an exposed state in the hollow part. pedestal.