JPH0116072Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an improvement of a sealing device for sealing between graphite blocks of a fixed reflector, which is a stacked assembly of graphite blocks built around the reactor core, in a gas-cooled nuclear reactor. .

First, an outline of the configuration of a high-temperature gas reactor as a gas-cooled nuclear reactor described above will be described with reference to FIG. In the figure,
1 is a reactor pressure vessel, 2 is a reactor core configured as an assembly of fuel bodies and movable reflectors, 3 is a high-temperature plenum block, 4 is a hearth insulation block, and 5 is formed between blocks 3 and 4. high temperature plenum,
Reference numeral 6 denotes a core support plate, 7 a diagram supporting the core structure, 8 an inlet pipe for gas as a primary coolant, and 9 an opening extending through the core support plate 6 and the hearth insulation block 4 toward the high-temperature plenum 5. A gas outlet pipe 10 is a fixed reflector that is the object of this invention, and this fixed reflector 1
0, as is well known, surrounds the reactor core and supports it from the sides to shield radiation from the core, and is constructed by stacking a large number of graphite blocks 11 vertically and circumferentially. . Note that the core barrel, core restraint mechanism, control rods, etc. are omitted in the figure.

The flow path of the cooling gas during operation in the high temperature gas furnace is as follows. That is, the cooling gas enters the pressure vessel 1 through the inlet pipe 8 at approximately 400°C, spreads around while cooling the lower surface of the core support plate 4, rises between the fixed reflector 10 and the pressure vessel 1, and then flows into the vessel. It changes direction at the top of the core and flows into the core 2. After being heated to about 1000°C through heat exchange with the fuel body, it collects in a high-temperature plenum, from which it flows out of the furnace through the outlet pipe 9. In addition, such gas circulation is performed by a gas blower outside the furnace,
The inlet pipe 8 serves as a high-pressure discharge side, and the outlet pipe 9 serves as a low-pressure suction side.

By the way, as mentioned above, since the fixed reflector 10 is constructed as an assembly assembled by abutting a large number of graphite blocks 11, as it is, there will be a small gap remaining between the abutting surfaces between the graphite blocks arranged on the left and right. As a result, some of the high-pressure cooling gas bypasses the high-temperature plenum instead of taking the normal route to the reactor core. Moreover, when this bypass flow occurs, a portion of the low-temperature gas introduced into the pressure vessel 1 goes through the short circuit and flows into the outlet pipe, so the effective flow rate of the cooling gas that normally flows inside the reactor core 2 decreases. As a result, not only does the heat extraction efficiency decrease, but also the heat removal from the fuel body is not performed sufficiently, which may lead to abnormal heating of the fuel body and damage to the furnace.

For this purpose, conventionally, sealing grooves are formed in the vertical and horizontal directions between the graphite blocks 11, and a sealing element consisting of a thin metal seal and a graphite seal is inserted into the groove, and A means is generally adopted in which the sealing element is pressed into close contact with the wall surface in the seal groove based on the pressure difference between the outer circumferential side and the inner circumferential side of the fixed reflector 10 to effect sealing. That is, in FIG. 2, the symbol 1
2 and 13 indicate a vertical seal piece and a horizontal seal piece inserted into the seal groove described above. Further, the seal groove is formed by forming a circumferential groove 14 on the outer peripheral surface of the graphite block 11 as shown in FIGS. 3a and 3b.
By assembling these graphite blocks vertically and horizontally, a space is defined between the graphite blocks. Fourth
5 and 5 show the conventional seal assembly structure described above, 15 is a seal groove, 16, 17
are graphite seals and metal seals constituting seal pieces 12 and 13, respectively; g is graphite block 1;
Figure 1 shows the gap that remains between the parts 1 and 1 that may cause gas leakage. The dimensions of the seal pieces 12 and 13 are, for example, about 7 mm thick and 30 mm wide, and the width d of the seal groove 15 is selected to be sufficiently larger than the thickness of the seal pieces in consideration of ease of assembly as will be described later. has been done. Further, in FIG. 5, the seal piece 12,
13 is pressed into close contact with the wall surface under the action pressure p based on the above-mentioned internal and external pressure difference. On the other hand, the fixed reflector is constructed by arranging graphite blocks 11 one by one in the circumferential direction.
Seal pieces 12 and 13 of a predetermined length, cut in advance according to the size of Incorporated.

By the way, in the process of constructing the fixed reflector, it is inevitable that some assembly errors will occur, and since the fixed reflector will be restrained by the core restraint mechanism after assembly, the position of the seal groove 15 on the top, bottom, left and right sides will vary. A deviation occurs. As a result, in the conventional structure in which the vertical seal pieces 12 and the horizontal seal pieces 13 and the vertical seal pieces 12 are butted against each other with their thin end surfaces, as shown in FIG. The parts are unstable, and even a slight assembly error between the graphite blocks can cause back-and-forth misalignment between the butting end faces of each seal piece, resulting in a cut in the seal and making it difficult to ensure a reliable seal. The seal effect cannot be expected. Moreover, when the above deviation becomes large,
In particular, when the vertical seal piece 12 is not overlapped vertically and the width d of the seal groove 15 is sufficiently larger than the thickness of the seal piece, the upper seal piece 12 is inserted into the remaining space in the lower seal groove 15. There is a risk of problems such as falling under its own weight. When such a trouble occurs, a portion of the seal piece is missing, making it impossible to obtain a sufficient sealing effect, and in order to repair this, the fixed reflector must be reassembled. Incidentally, the accident of the vertical seal piece 12 falling off as described above can occur not only when the fixed reflector is assembled, but also due to an earthquake or the like after assembly.

This idea was developed in consideration of the above points, and its purpose was to eliminate the drawbacks of the conventional structure, provide stable support for the seal piece, and absorb assembly errors of the fixed reflector to provide a reliable seal. The purpose of the present invention is to provide a fixed reflector sealing device with high performance and reliability.

According to this invention, a cube-shaped seal piece support block whose length on one side is at least greater than the width of the seal groove is provided at the intersection of the seal groove where the vertical seal piece and the horizontal seal piece intersect. This is achieved by inserting and supporting the seal pieces on a block, and having the end faces of each seal piece come into close contact with the seal piece support block.

This invention will be described in detail based on the illustrated embodiments.

In FIGS. 6 to 8, the vertical and horizontal sealing pieces 12 and 13 intersect, where the corners of the graphite blocks 11 arranged vertically and horizontally gather together. A seal piece support block indicated by reference numeral 18 is inserted and installed at the intersection of the seal grooves, and a vertical seal piece 1 is mounted on the wall surface of this seal piece support block 18.
2 and each end face of the horizontal seal piece 13 are in close contact with each other. Here, the seal piece support block 1
8 is a cube made of graphite combined with metal seals, and its size is selected such that the length l of one side is at least larger than the width dimension d of the seal groove 15 shown in FIG. As shown in FIG. 8, the graphite block 11 is supported by being fitted into recesses 19 cut out at the four corners of a circumferential groove 14 formed in the graphite block 11.

According to the above configuration, the seal piece support block 1
8 is larger than the width of the seal groove 15,
and held in place. Therefore,
First, with this support block 18 as a reference, each seal piece 1 is
Correct positioning can be achieved by bringing the end faces of 2 and 13 into contact with the wide wall surface of the support block 18.
The seal pieces can be easily assembled and supported stably. In addition, even if the position of each seal piece is misaligned due to an assembly error of the fixed reflector, there is no gap between the seal pieces that impairs the sealing effect as in the conventional case. Surface contact between the end surfaces of the seals 12 and 13 and the support block 18 is maintained, and the occurrence of breaks in the seal can be prevented. Moreover, especially regarding the seal structure in the vertical direction, communication between the upper and lower seal grooves 15 is cut off between the vertically arranged graphite blocks 11 due to the interposition of the seal piece support block 18, so that the upper seal piece 12 is connected to the lower seal piece 12. The practical effect is that the seal structure can be easily assembled, such as eliminating any fear of troubles such as falling into the seal groove, and high sealing performance can be maintained even if there is an assembly error of the fixed reflector.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the configuration of a high-temperature gas furnace, FIG. 2 is a perspective view of a partial configuration of a fixed reflector equipped with a sealing element,
3a and 3b are a side view and a partially cutaway sectional view of the graphite block, FIG. 4 is an assembled structural diagram of a conventional sealing device, FIG. 5 is a sectional view of the seal groove in FIG. 4, and FIGS. FIG. 8 shows an embodiment of this invention, FIG. 6 is an assembled perspective view of a sealing device, FIG. 7 is an exploded view of FIG. 6, and FIG. 8 is a perspective view of a graphite block. 2... Core, 10... Fixed reflector, 11...
Graphite block, 12... Lead direction seal piece, 13...
...Horizontal seal piece, 15...Seal groove, 18...
...Seal piece support block.

Claims (1)

[Scope of utility model registration request] Vertical and horizontal seal grooves are formed between each graphite block of the fixed reflector, which is a stacked assembly of a large number of graphite blocks constructed around the core, and each of the seal grooves In a sealing device for a fixed reflector, a vertical seal piece and a horizontal seal piece are inserted into the fixed reflector, and each seal piece is pressed tightly against the wall surface of the seal groove due to the pressure difference between the inside and outside of the fixed reflector. At the intersection of the seal grooves where the direction seal piece and the horizontal seal piece intersect, a cube-shaped seal piece support block whose length on one side is at least larger than the seal groove width is inserted by being carried by a graphite block. 1. A sealing device for a fixed reflector of a gas-cooled nuclear reactor, characterized in that the end face of each seal piece is brought into close contact with the seal piece support block.