JPS6140356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-furnace restraint device for preventing displacement of a graphite block due to heat.

High-temperature gas furnaces are an improvement over conventional gas-cooled furnaces to make them more economical, but because the outlet coolant temperature of these high-temperature gas furnaces is as high as 1000°C, graphite blocks are placed inside the metal container. They are stacked together to form the core and the surrounding area.

The structure of a conventional high-temperature gas furnace is shown in Figure 1. The fuel block 1 is supported by a plenum block 2, and its weight is transmitted to the insulation block 4 through three posts 3 per plenum block 2.These core blocks are surrounded by graphite blocks 5, which are reflectors. It is. This graphite block 5
horizontal displacement during an earthquake is restrained via a stopper 7 attached to a metal core barrel 6 surrounding it. These reactor core components are entirely placed on a support plate 8, and their weight is further transmitted to the reactor pressure vessel 11 via a diagram 9 and a bracket 10. In the above structure, the coefficient of thermal expansion of graphite is about 1/5 of that of metal, so the amount of thermal expansion of the support plate 8 and core barrel 6 during reactor operation is due to the heat of the graphite block such as the reflector. This becomes larger than the amount of expansion, and gaps are created between the graphite blocks and between the reflector and the stopper.

Figure 2 shows the state of the reactor during operation, with a gap _W1 between graphite block 5 and stopper 7, and a gap _W3 between plenum block 2 and graphite block 5.
However, gaps _W4 are created between the heat insulating blocks 4. For this reason, when vibrations are applied to the pressure vessel due to an earthquake or the like, there is a risk that the blocks will collide with each other, causing damage to the blocks or making it difficult to insert the control rods, resulting in a major accident.

SUMMARY OF THE INVENTION An object of the present invention is to provide a core restraint device that eliminates the above-mentioned problems and restrains the core so that no gaps are created in the above-mentioned portions, thereby increasing the safety of the nuclear reactor.

In short, this invention rotatably attaches an operating rod to a core barrel and a stopper, connects the other ends of these two operating rods, and connects a rod-shaped body made of a metal with a large coefficient of thermal expansion to this connecting portion. A pressing portion is arranged so that the expansion of the metal rod is transmitted to the stopper via the operating rod during operation of the nuclear reactor, and the reactor core is restrained by the stopper.

Embodiments of the present invention will be described below based on the drawings.

3 and 4, 12a and 1
2b is an operating rod, one end of the operating rod 12a is connected to the stopper 7, and one end of the operating rod 12b is connected to the core barrel 6.
are rotatably attached to each. Reference numeral 20 is a connecting portion connecting the free ends of these operating rods 12a and 12b, and the total length of each operating rod 12a, 12b is formed to be longer than the distance W between the mounting positions of these operating rods. By connecting the two operating rods, a generally dogleg-shaped link mechanism is formed as a whole. Reference numeral 13 is a sliding plate on which the stopper 7 slides.

Next, reference numeral 14 denotes a rod-shaped body made of a metal having a large coefficient of thermal expansion, preferably a metal having a coefficient of thermal expansion larger than that of the core barrel 6. For example, when the constituent metal of the core barrel 6 is low alloy steel, the rod-shaped body 14 is preferably made of stainless steel.

The connecting portion 20 of the link mechanism is connected to this rod-shaped body 14.
It is in a state where it is placed on a pressing part 21 formed in .

5 and 6 show the operating state of the device described above. Figure 5 shows the state when the reactor is shut down.
Figure 6 shows the state during reactor operation.

First, when the reactor starts operating, the angle between the operating rods 12a and 12b at the time of shutdown is α, and the distance between the attachment parts of each operating rod is W, the rod-shaped body 1 is
4 expands in the X direction, which causes the actuating rods 12a,
The connecting portions 20 of 12b are pushed up in the same direction, the distance W between the attachment portions is increased to _W1 , and the stopper 7 is moved in the Y direction. The pressing force of the stopper 7 prevents the graphite block 5 from moving toward the core barrel 6 side. A plurality of these in-core restraint devices are arranged within the annular space formed between the wall surface formed by the graphite block 5 and the core barrel to effectively restrain the core.

By carrying out this invention, the displacement of the graphite block can be restrained at all times regardless of the thermal expansion of the constituent materials within the reactor, so that the nuclear reactor can be operated safely.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a high-temperature gas furnace, FIG. 2 is a perspective view showing the structure inside the high-temperature gas furnace, FIG. 3 is a side view of the in-furnace restraint device according to the present invention, and FIG. 3 is an AA view, FIG. 5 is a side view of the in-core restraint device when the reactor is stopped, and FIG. 6 is a side view of the in-core restraint device when the reactor is in operation. 5...graphite block, 6...core barrel, 7...
...stopper, 12a, 12b...operating rod, 14...
... Rod-shaped body, 20 ... Connection part, 21 ... Pressing part.

Claims (1)

[Claims] 1 One end of the operating rod is rotatably attached to the stopper that presses the graphite block and the core barrel, respectively.
By connecting the free ends of these two operating rods, a substantially dogleg-shaped link mechanism is interposed between the stopper and the core barrel, and a rod-shaped pressing portion is arranged at the connecting portion of this link mechanism. A core restraint device characterized in that the expansion force of a rod-shaped body is used for restraining a graphite block through a link mechanism and a stopper.