JPS6130236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a support structure for a torus shell that forms a pressure suppression chamber of a reactor containment vessel, and is particularly applicable to a pressure suppression chamber that suppresses an abnormal rise in pressure in the event of an accident such as a pipe rupture. It absorbs the external force that acts on the torus shell due to dynamic loads and seismic motion brought to the ground and the foundation of the reactor equipment due to an earthquake, reducing the stress applied to it and improving the structural reliability and soundness of the torus shell. The present invention relates to a torus shell support structure that can be improved and achieve as safe operation of a nuclear reactor as possible.

In general, a nuclear reactor containment vessel 1, commonly referred to as a MARK-type, as shown in FIG. 1, is known as a reactor containment vessel employed in nuclear reactor equipment.
Inside the containment vessel 1, a reactor pressure vessel 2 is housed, and on the outside of the bottom of the containment vessel 1,
A torus shell 4 in which circular pipes forming an annular pressure suppression chamber 3 are sequentially connected is provided surrounding this. This torus shell 4 is provided with legs 6 to support it on a foundation 5. In addition, between the torus shell 4 and the containment vessel 1, a pressure suppression chamber 3 is provided for discharging the steam generated in the containment vessel 1.
A vent pipe 9 with a downcomer 8 is provided leading to a pressure suppression pool 7 provided within. Furthermore, this torus shell 4 and pressure vessel 2
It is connected via a relief valve 11 to the main steam pipe 10 led out from the pool 7 of the pressure suppression chamber 3.
An exhaust pipe 12 is provided which is introduced into the exhaust pipe. The following external force due to the pressure artery acts on the torus shell 4 forming the pressure suppression chamber 3 into which the various pipe systems have been introduced.

First, when the steam pressure in the reactor pressure vessel 2 rises abnormally, a portion of the high temperature and high pressure steam is transferred from the main steam pipe 10 to the pressure suppression pool via the relief valve 11 and the exhaust pipe 12. 7 as air bubbles. These bubbles rapidly expand in the water in the pool 7 and press the surrounding water. The bubbles continue to expand slightly due to the inertia of the water even after their internal pressure becomes negative with respect to the internal pressure of the pressure suppression chamber 3, but the relationship gradually reverses and they are pressed and compressed by the surrounding water. While repeating this process, the bubbles rise due to buoyancy, reach the water surface of the pool 7, and burst.
During this time, pressure pulsations occur in the water in the pool 7 as the bubbles repeatedly expand and contract.

Second, when the coolant circulating in the reactor pressure vessel 2 or the like leaks and is lost for some reason, the containment vessel 1 is filled with a mixture of high temperature and high pressure steam and air. This high temperature/high pressure mixture is transferred to a pressure suppression pool 7 via a vent pipe 9 and a downcomer 8.
released into. At this time, the air or steam pressurized to ultra-high pressure expands rapidly in the water, creating a bubble flow and applying shocking pressure to the bottom of the torus shell 4, and the bubbles receive the reaction force. It reaches the water surface and explodes, shockingly pressurizing the void inside the pressure suppression chamber 3 and the water surface. Furthermore, when the internal pressures in the containment vessel 1 and the pressure suppression chamber 3 become approximately equal to each other, pressure pulsations will occur in the pool 7 due to the steam condensation action of the bubbles accumulated around the steam discharge port of the downcomer 8.

Further, accompanying the first and second pressure pulsations, the temperature and internal pressure in the pressure suppression chamber 3 rise due to the high temperature steam discharged from the pipe systems, causing the torus shell 4 to expand.

The above is the pressure suppression chamber 3 as a safety device installed to deal with unexpected accidents during the operation of nuclear reactor equipment.
This is an endogenous external force that occurs on the torus shell 4 that forms the torus shell 4, but earthquakes are also mentioned as an external external force.

It is generally believed that seismic waves generate unidirectional seismic motion along the ground surface. This seismic motion causes the foundation 5 on which the nuclear reactor equipment is installed to shake, and the torus shell 4 supported by the legs 6 erected from the foundation 5 to violently shake in one direction.

Various support structures for the torus shell 4 have been devised in order to reduce the stress caused by these external forces.

Conventionally, as an example, the one shown in FIG. 2 is known. On both sides 13a, 13a of the lower half of the torus shell 4, a support is provided that is erected from the foundation 5 to support the torus shell 4, and is designed to support the expansion of the torus shell 4 in its radial direction as the temperature of the pressure suppression chamber 3 increases. Pipe-shaped support legs 14, 14, which are made freely tiltable by means of pin connections or the like, are fixedly provided to allow the movement. The support legs 14, 14 are provided at each joint where 16 circular tubes are joined to each other to form an annular torus shell 4. In addition, the torus shell 4 is provided at the lower central portion 13b of the torus shell 4 in order to attenuate the horizontal force caused by an earthquake between this and the foundation 5, and to suppress the horizontal movement of the entire torus shell 4. An earthquake-resistant support leg 15 is made movable in the radial direction of the torus shell 4 by interlocking an integrally provided toothed bracket and a toothed bracket installed on the foundation 5 with a pin connection or the like. is provided.
The earthquake-resistant support legs 15 were installed at eight locations along the circumferential direction of the torus shell 4 at predetermined intervals.

By the way, in the conventional support structure, the torus shell 4 due to the above-mentioned first and second pressure pulsations
The expansion and contraction deformation of the lower half was carried only by the support legs 14, 14 fixed to the torus shell 4, but these support legs 14, 14 had a relatively low rigidity structure due to pin connections, etc. , there was a tendency for large stress to be generated at the joint between the torus shell 4 and the support legs 14, 14. In addition, this support leg 1
4, 14 and the seismic supporting legs 15 are installed separately, which requires a large number of man-hours at the construction site and prolongs the construction period. Furthermore, earthquake-resistant support legs 15
Because the structure is complex and the equipment requires many days of work, the number of installations was limited to the necessary limit, but it was desired to install a relatively large number of them for earthquake resistance reasons.

The present invention was devised in view of the problems of conventional torus shell support structures and to effectively solve them.

The purpose of the present invention is to provide both the supporting function and the seismic function of the torus shell, and to rigidly support the torus shell while allowing its movement in the radial and axial directions. A torus shell support structure that can collectively absorb external forces such as seismic vibrations caused by earthquakes, reduce stress generated in the torus shell, achieve safe operation of the reactor as much as possible, and enable equipment work to be carried out in a short period of time. Our goal is to provide the following.

Next, a preferred embodiment of the torus shell support structure according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 3, support plates 16 are provided perpendicularly between the lower half 13 of the torus shell 4 and the foundation 5 in order to support the torus shell 4 on the foundation 5. This support plate 16 is formed into a saddle shape by cutting a flat plate along the outer shape of the lower half portion 13 of the torus shell 4, and is welded to the torus shell 4. Foundation side end 1 of this support plate 16
7 is integrally provided with a flat seat 18 along which the support plate 16 is seated on the foundation 5. On the other hand, a flat receiving seat 19 is provided on the foundation 5 along the seat 18 on which a support plate 16 for supporting the torus shell 4 is seated. A sliding plate 20 is interposed between the seat 18 and the receiving seat 19 to prevent the movement of one from being transmitted to the other. In order to connect the support plate 16 seated on the foundation 5 to the foundation 5 in this manner, end bases 21, 21 and a center base 22 are formed at both ends and the center of the support plate 16 on the foundation 5 side. Figures 4 and 5
As shown in the figure, the end base 21 includes a seat 18, a sliding plate 2
0 and the receiving seat 19 are arranged in parallel, and an anchor bolt 24 buried in the foundation 5 passes through it, and a nut 26 is fastened to this via a washer 25 on the upper surface of the seat 18 for support. Board 1
6 and the foundation 5 are connected to each other. In particular, as shown in FIG. 4, the seat 18 and slide plate 20 side of the hole 23 is formed to have a relatively long diameter along the longitudinal direction of the support plate 16, that is, the radial direction of the torus shell 4. Therefore, the torus shell 4 has a sliding plate 20 provided on the receiving seat 19, and a sliding plate 20 provided on the receiving seat 19, and the sliding plate 20 provided on the receiving seat 19.
By the elongated hole 23a formed in 8,
Movement in the radial direction (indicated by arrow C in the figure) is allowed by the gap between the anchor bolt 24 and the hole 23a. With this configuration, radial movement of the support plate 16 due to thermal expansion and pressure pulsations of the torus shell 4 is absorbed, and stress generated in the torus shell 4 is reduced.
On the other hand, as shown in FIGS. 6 and 7, the center base 22 has a seat 18,
A large number of holes 27 are arranged in parallel to communicate between the sliding plate 20 and the receiving seat 19, through which an anchor bolt 24 buried in the foundation 5 passes, and a nut 26 is fastened to this via a washer 25 on the upper surface of the seat 18. The support plate 16 and the foundation 5 are configured to be connected. Especially when it comes to the center base 22, the foundation 5
While forming gaps S, S which are embedded in and protrude from the receiving seat 19 and have a predetermined distance from the seat 18 and the sliding plate 20, these are arranged at a predetermined length along the longitudinal direction of the support plate 16. Stop plates 28, 28 are arranged in parallel to hold the length of the holder. Further, as shown in FIG. 7, the seat 18 and sliding plate 20 side of the hole 27 is formed along the axial direction of the torus shell 4 and has a relatively larger major axis than the gaps S, S. Therefore, in the case of the center base 22, the sliding plate 20 provided on the receiving seat 19 and the sliding plate 20 provided on the receiving seat 19 and the seat 18
The elongated hole 27a formed in the base 5 or the torus shell 4 is formed within the gap S, S between the stop plates 28, 28, the sliding plate 20, and the seat 18.
movement (indicated by arrow D in the figure) is allowed in the axial direction. The shearing force between the seat 18 on the torus shell 4 side and the receiving seat 19 on the foundation 5 side due to this movement is absorbed by the stop plates 28, 28. On the other hand, the anchor bolt 24 has a hole 27 having a relatively larger major axis than the gaps S, S.
a is always spaced apart from the seat 18 and the sliding plate 20, and is configured to connect the support plate 16 and the foundation 5 without being subjected to shearing force due to movement and without being damaged. With this configuration, as shown in FIG. 7, movement of the foundation 5 in the four-axis directions of the torus shell due to an earthquake is absorbed, and
Since the acting horizontal force is absorbed by the stop plates 28, 28, the external force, ie, stress, acting on the torus shell 4 via the support plate 16 is reduced.
Further, the anchor bolts 24 provided at the center base 22 and the end bases 21, 21 restrict vertical contraction of the torus shell 4 due to pressure pulsations.

By the way, as shown in FIGS. 3 to 7, between the center base 22 and end bases 21, 21, and the torus shell 4, the rigidity of the support plate 16 is kept high and the torus is formed as much as possible. In order to increase the rigidity of the shell 4, a large number of reinforcing plates 29 are arranged in parallel perpendicularly to the supporting plate 16. Further, as shown in FIG. 8, one unit 30 as a support structure equipped with these support plates 16 and the like includes a joint 3 where 16 circular pipes 31 are joined to each other to form an annular torus shell 4.
2 are provided one by one.

The operation of the above configuration will be described.

First, the operation of each unit 30 will be explained. The torus shell 4 undergoes minute deformation due to pressure pulsations caused by the causes mentioned above and external forces acting as thermal stress accompanying the pressure pulsations. In the deformation of the torus shell 4, in the radial direction, as shown in FIG.
Due to its rigidity, the stress applied to the torus shell 4 can be reduced and the amount of deformation thereof can be suppressed, and on the other hand, the sliding plate 20 and the elongated hole 23a provided at the end bases 21, 21 of the support plate 16, etc. By allowing the deformation to some extent, the stress applied to the torus shell 4 can be reduced, and the strength of the structure can be maintained. Also, Taurus Ciel 4
Regarding the vertical direction of deformation of the
The torus shell 4 can be rigidly supported on the foundation 5 by restricting its deformation by the anchor bolt 24 connecting the torus shell 4 with the base 5.

On the other hand, the torus shell 4 is also subject to deformation due to unidirectional seismic motion caused by an earthquake. Although this deformation is relatively large, as shown in FIG.
The ability of the torus shell 4 to follow the rocking of the foundation 5 can be suppressed, and the shear force between them is absorbed by the stop plates 28, 28, thereby attenuating the external force acting directly on the torus shell 4 and reducing the amount of deformation. This means that the stress can be kept small, the stress can be reduced, and the strength can be maintained.

FIG. 8 shows how the units 30 having the above-mentioned functions are arranged throughout the axial direction of the torus shell 4. During pressure pulsation and thermal expansion, the entire torus shell 4 moves as shown by arrow C.
Directional movement is allowed. On the other hand, for earthquake motion in the direction of arrow E, the direction and torus shell 4
An external force (indicated by arrow D in the figure) corresponding to the cos component due to the declination angle with respect to the axial direction acts on each center base 22, and the external force due to the earthquake motion is It will be distributed in the axial direction. In the illustrated example, of the 16 installed units 30, 8 units are substantially subjected to seismic motion and the stress in the torus shell 4 can be reduced.

As described above, the torus shell support structure according to the present invention has a base 21 that has high rigidity and allows movement in order to release external forces such as pressure pulsations and earthquakes.
By arranging a large number of units 30 each having 21 and 22, it is possible to firmly support the torus shell 4 while smoothly reducing the stress applied thereto. In addition, by providing both functions in one unit 30 instead of manufacturing and attaching support legs and seismic support legs separately as in the past, equipment work can be simplified and the construction period can be shortened as much as possible. It can be achieved.

Note that a long hole 2 is provided in the seat 18 of the central base 22.
Of course, instead of drilling 7a, an elongated hole may be formed in the receiving seat 19. It goes without saying that the support plate 16 may be formed by cutting out the support plate 16 between the center base 22 and the end bases 21, 21.

Furthermore, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that the present invention can be modified and implemented in various ways without changing the gist.

As described above, according to the present invention, the following excellent effects are exhibited.

(1) The support plate disposed to support the torus shell is formed with high rigidity to firmly support the torus shell, and the end base of the support plate is allowed to move in the radial direction of the torus shell to prevent pressure pulsations and heat. It allows deformation of the torus shell due to stress, and allows the central base of the support plate to move in the axial direction of the torus shell, thereby attenuating the horizontal force caused by earthquakes and reducing the external force that acts directly on the torus shell. By firmly connecting these to the torus shell with anchor bolts that connect it to the foundation in order to restrict vertical contraction of the torus shell, the stress applied to the torus shell can be reduced, so the strength of the structure can be maintained, and the strength of the torus shell can be maintained. Improved reliability, soundness, and durability can be achieved.

(2) The support plate has both the support function of the torus shell and the earthquake resistance function, which simplifies manufacturing work and on-site installation work, shortens the construction period, and reduces construction costs. can.

(3) Since manufacturing and installation work are easy, as many as possible can be installed, the torus shell can be supported reliably, and earthquake resistance can be fully demonstrated.

(4) It has a relatively simple structure, can be easily adopted, and can contribute to the safe operation of nuclear reactors.

[Brief explanation of the drawing]

FIG. 1 is a schematic side sectional view showing the reactor containment vessel;
Fig. 2 is a side sectional view showing a conventional torus shell support structure, Fig. 3 is a side sectional view showing a preferred embodiment of the torus shell support structure according to the present invention, and Fig. 4 is an enlarged view of section A in Fig. 3. Figure 5 is a - line arrow view in Figure 4, Figure 6 is B in Figure 3.
FIG. 7 is a view taken along the - line in FIG. 6, and FIG. 8 is a plan view showing the arrangement of the torus shell support structure according to the present invention with respect to the torus shell. In the figure, 1 is a reactor containment vessel, 4 is a torus shell, 5 is a foundation, 16 is a support plate, 20 is a sliding plate, 2
1 and 21 are end bases, and 22 is a center base.

Claims (1)

[Claims] 1. In a torus shell support structure that supports a torus shell at a predetermined interval on a foundation, which is provided in an annular shape to surround the bottom of a reactor containment vessel and controls pressure fluctuations within the vessel, the torus shell is A saddle-shaped support plate is provided at the lower part to support this from the foundation, and an end base and a center base that sit on the foundation are formed at both ends and the center of the support plate on the foundation side, and these bases A sliding plate is interposed between the support plate and the foundation to connect the end base to the foundation to allow movement of the torus shell in the radial direction, and connect the center base to the torus shell. A torus shell support structure connected to the foundation to allow movement in the axial direction of the torus shell.