JPH02243994A - Core supporting device of gas-cooled reactor - Google Patents

Abstract

PURPOSE:To prevent the generation of an excessive thermal stress by a temp. difference by supporting a supporting plate atop the head part of the supporting bolts implanted on supporting posts and a sealing plate atop the supporting posts, respectively slidably. CONSTITUTION:Key grooves 12 of a hollow groove shape facing the radial direction R of the core are formed on the rear surface of the plate 7 in correspondence to the installation position of the supporting posts 9 to the blocks arraying on the outermost periphery among the respective blocks 7a constituting the disk-shaped supporting plate 7. Key members 13 fitting into the grooves 12 are fitted on the outer periphery of the head part of the supporting bolts 11 screwed and implanted atop the post 9 side thereof as against the above grooves and are fixed by means of pins 14 to the head part of the bolts 11. The upper surfaces in the head part of the bolts 11 are spot-faced with seat surfaces. Projecting parts 15 are bulged downward and formed at the center in the grooves 12 so as to come into slidable contact with the seat surfaces. Oblong-hole-shaped through-holes 16 for the supporting bolts facing the direction R are bored at the points of the sealing plate 8 where the posts 9 are to be installed so that the sealing plate is carried atop the posts 9 slidably in tight contact therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a core support device for supporting core components of a gas-cooled nuclear reactor on a diagonal grid installed in a reactor vessel.

[Conventional technology]

First, the conventional structure of this type of core support device will be explained with reference to FIGS. 1 to 3. In the figure, 1 is a movable reflector block that constitutes the reactor core, 2 is a high-temperature plenum block, 3 is a heat insulation block, and 4 is a fixed reflector that surrounds the outer periphery of each block, and these constitute the reactor core. . on the other hand,
A diagonal grid 5 is installed at the bottom of the reactor vessel (not shown), and the core components are supported on the grid via a core support device described below. Note that 6 is a core barrel. That is, the core support device is divided into blocks 7a arranged on the same plane corresponding to each divided region of the core.
a support bra ridge 17 which is an assembly of support plates 17, a seal plate 8 that covers the lower surface of the support plate 7, and a support for supporting these members on the grid 5 while leaving a gas passage gap between them and the upper surface of the grid 5. It consists of post 9, etc. Here, the detailed conventional structure of the support post part is shown in FIG. 2. As shown in FIG. has been done. On the other hand, the seal plate 8 has a hole through which a spacer 10 and a bolt 11 pass through at a location corresponding to the support post 9.
While supported on the upper surface of the support post 9, the peripheral edge of the hole and the support post 9 are welded and sealed.

Note that the support post 9 is welded onto the grid 5 and is firmly connected thereto.

With the above configuration, the weight load of the core components is transmitted to the grid 5 via the support plate 7, the spacer 10, and the support post 9. On the other hand, low-temperature cooling gas of approximately 400°C, which is sent into the furnace vessel via a cooling gas inlet pipe (not shown), flows through the gap passage between the seal plate 8 and the grid 5 as shown by arrow A, and is fixedly reflected. It rises along the outer periphery of the body 4 between the core barrel 6 and flows into the core from the upper part of the core. The cooling gas, which has been heated to a temperature of 800 to 1000° C. through the fuel channels in the core, is collected in a high-temperature plenum and sent from there to a heat exchange facility outside the reactor via a cooling gas outlet pipe (not shown). In this case, the seal plate 8 prevents the high temperature gas from leaking to the low temperature side.

[Problem to be solved by the invention]

However, the structure of the conventional core support device described above has the following problems. In other words, during steady operation of a nuclear reactor, there is a temperature difference between the support plate 7, seal plate 8, and grid 5, and this causes a difference in thermal expansion in the horizontal direction. In this case, since each member making up the core support device is connected together by bolts 11, welding, etc., the difference in thermal expansion cannot be freely released, and as a result, large thermal stress is generated everywhere. . In addition, during an emergency shutdown of a nuclear reactor, the cooling gas flow rate decreases and the heat accumulated in the insulation block 31 is dissipated, further increasing the temperature difference described above. Seal weld between plate 8 and support post 9, or support post 9 and grid 5
There is a risk of damage to the welded joints. Furthermore, a grid 5 of a lattice-like beam plate structure that should originally be a support for vertical loads.
It is not reasonable from a design standpoint to provide strength against horizontal loads.

This invention has been made in consideration of the above points, and aims to provide a core support device that satisfies the functions necessary for core support and is free from the risk of generating excessive thermal stress due to temperature differences. .

[Means to solve the problem]

Achieve the above objectives. To achieve this, the present invention supports a support plate on the top surface of the head of a support bolt implanted on a support post, and a seal plate on the top surface of the support post so as to be slidable in the radial direction with respect to the center of the reactor core. The heavy load of the reactor core is supported by the grid without restricting the thermal expansion difference between each member, and the support bolt through hole in the seal plate is sealed between the seal plate and the support post and between the seal plate and the support bolt. This is obtained by overlapping the head of the

〔Example〕

The present invention will be explained below based on illustrated embodiments.

4 and 7 show the structures of the support parts indicated by symbols P and Q in FIG. 3, respectively, and FIG.
-■ sectional view and FIG. 6 are partial plan views of the seal plate in FIGS. 4 and 7, and the same reference numerals as in FIG. 2 indicate the same members. First, for the outermost block among the blocks 7a constituting the disk-shaped support plate 7 shown in FIG. 3, the installation positions of the support posts 9 are as shown in FIGS. Correspondingly, a concave key groove 12 facing in the radial direction R of the core is formed on the lower surface of the support plate 7, and opposite to this, the support post side groove is screwed into the upper surface of the key groove 12. A key member 13 that fits into the key groove 124 is fitted onto the outer periphery of the head of the support bolt 11, and is fixed to the bolt head by a pin 14 in the direction of the key groove 12. Furthermore, the upper surface of the head of the support bolt 11 is machined with a seat surface, and a convex portion 15 is provided downward at the center of the keyway 12 on the support plate side so as to be in slidable contact with the seat surface. A bulge is formed. On the other hand, the seal plate 8 has elongated support bolt through holes 16 facing in the radial direction R of the core, as shown in FIG.
It is slidably supported in close contact with the upper surface of. On the other hand, the structure of the support section indicated by the symbol Q in FIG. 3 is as shown in FIG. 7, and compared to FIG. It is structured similarly.

Next, the assembly order of the above configuration will be described. First, the seal plate 8 is placed on the upper surface of each support post 9 by positioning it. Next, screw the support pole 11 through the bolt through hole 16 of the seal plate 8 for each support post. In this case, the bolt 11 is tightened so as to set a minute seal gap g between the bolt head and the upper surface of the seal plate 8 to limit gas leakage.

In addition, the overlapping dimensions of each member are determined in advance so that sufficient overlapping dimensions t and t' can be obtained between the seal plate 8 and the upper surface of the support post 9 and between the seal plate 8 and the lower surface of the head of the support bolt. This confirms sufficient sealing performance at the core. After the seal plate 8 is assembled in the above operation, the key member 13 is attached to the head of the support bolt 11 for the support portion P, and the key member 13 is fixed to the support bolt 11 with the pin 14 in a predetermined direction. In this state, the blocks 7a of the support plate 7 are installed over the upper surfaces of the bolt heads of the support bolts 11 while keying the blocks to each other. In this case, in order to equalize the level of the upper surface between each block 7a, the lower surface convex part 15 of the complete support plate is replaced with a level adjustment means, such as a leveling screw, and the installation level is adjusted for each block. It is better to After the core support device is assembled in this way, the core is assembled above it.

With the above configuration, the support plate 7,
Seal plate 8. The thermal expansion difference that occurs in the radial direction of the core based on the temperature difference between the grids 5 is absorbed by the sliding movement between the support post 9 and the seal plate 8, and the sliding movement between the upper surface of the support bolt and the support plate 7, Since they are not constrained by each other, excessive thermal stress will not occur. Moreover, support plate 7 and support bolt 1
1 and the long seal plate 8, the mutual movement of each member is restrained and the load is transmitted to the grid 5 in response to non-axisymmetric horizontal loads such as in the event of an earthquake. Since it can be supported, high earthquake resistance can be obtained. Furthermore, in order to minimize the possibility of the support post 9 or the support bolt 11 falling due to the horizontal load applied during sliding due to the absorption of the thermal expansion difference mentioned above, or galling due to uneven contact, etc. It is preferable to set the sliding surface between the support bolt, support bolt, seal plate, and support plate at a level close to the center of the thickness of the seal plate and support plate. For this reason, in the illustrated embodiment, the lower surface level of the convex portion 15 in the support plate 7 is selected to be located approximately at the center of the thickness of the support plate,
Further, regarding the seal plate 8, the surface area that contacts the upper surface E of the support post 9 is counterbored so that the sliding surface is as close to the center of the thickness of the seal plate as possible.

〔Effect of the invention〕

As described above, according to the present invention, there is a space between the upper surface of the head of the support bolt implanted in the support post and the support plate supported on this, and between the upper surface of the support post and the seal plate supported on this. to allow mutual sliding between the
By assembling and configuring the core support device with a structure that does not restrict the thermal expansion difference between the two components, it is possible to perform the function of supporting the weight load necessary as a support device for the core components, and to maintain the function of supporting the weight load between the high temperature side and the low temperature side. While satisfying the sealing function to prevent cooling gas from leaking, it also allows the thermal expansion between the component parts that occurs during furnace operation to escape without restraint, preventing the generation of excessive thermal stress and improving reliability. can be achieved.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing the general structure of the hearth part in a gas-cooled nuclear reactor, Figure 2 is an enlarged cross-sectional view showing the conventional structure of section B in Figure 1, and Figure 3 is a cross-sectional view of the support post. Top view of support plate shown with arrangement, Figures 4 and 7
The figures are enlarged vertical cross-sectional views showing the configuration of the support parts indicated by P and Q in Figure 3 on the disaster side according to the present invention, Figure 5 is a cross-sectional view taken along arrow v-■ in Figure 4, and Figure 6 7 is a partial plan view of the seal plate in FIGS. 4 and 7. FIG. 5... Grid, 7... Support plate, 7a.
...Block, 8...Seal plate, 9...Support post, 11...Support bolt, 12...Keyway, 1
3...Key member, 16...Support bolt through hole, -R
...radial direction of the reactor core. 1 shout h mi〈kuzu fig. 4

Claims (1)

[Scope of Claims] 1) A core support device that supports core components on a grid, comprising a support plate for the core components as a block assembly arranged on the same plane, and a seal that covers the lower surface of the support plate. It consists of a support post fixedly installed on the grid corresponding to each block of the plate and support plate, and a support bolt screwed onto the top surface of the support post, and a support is attached to the top surface of the head of the support bolt. A core support device for a gas-cooled nuclear reactor, characterized in that seal plates are mounted and supported on the upper surfaces of support posts so as to be slidable in the radial direction with respect to the center of the reactor core. 2) In the core support device according to claim 1, a key groove in the radial direction of the core is formed on the lower surface of the support plate, and a key member connected to the support bolt head is fitted into this key groove. A core support device for a gas-cooled nuclear reactor characterized by: 3) A core support device for a gas-cooled nuclear reactor according to claim 1, characterized in that a level adjustment means is provided on the support plate side opposite to the upper surface of the head of the support bolt. Device. 4) A core support device for a gas-cooled nuclear reactor according to claim 1, characterized in that long holes in the radial direction of the core are bored in the support bolt penetration portions on the seal plate. Device. 5) In the core support device according to claim 1, the sliding surfaces between the support bolt and the support plate and between the support post and the seal plate are at the center of the thickness of the support plate and the seal plate, respectively. A core support device for a gas-cooled nuclear reactor characterized by being set at a height close to .