JPS6118712B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear reactor body cover, and more particularly to a dual rotary reactor body cover.

In the prior art, a double rotary reactor main body lid having a fuel handling function has a structure as shown in FIGS. 1 to 3. That is, the reactor vessel 2 housing the reactor core 1 is closed at its upper part by the reactor body lid 3. The reactor body lid 3 includes a large rotating plug 4,
The small rotation plug 7 has a rotation center 6 eccentric from the rotation center 5 of the large rotation plug 4 by a predetermined eccentric amount. The small rotation plug 7 is provided with a core upper structure 9 having a central axis 8 spaced apart from the rotation center 6 of the small rotation plug 7 by a distance equal to the eccentricity described above. Therefore, in the position shown in FIG. 2, the rotation center 5 and the central axis 8 coincide. The small rotation plug 7 is also provided with a through hole 10 which serves both as an in-core fuel transfer device and an out-of-core fuel transfer device. The central axis 11 of the through hole 10 is located at a position radially symmetrical to the central axis 8 of the core upper structure 9 with respect to the rotation center 6 of the small rotating plug 7, and the in-core fuel rack 12
It lies on the maximum pitch circle 16. In other words, these central axes 8 and 11 are 180 degrees relative to the rotation center 6.
It is located at a position displaced by an angle of °.

When the through hole 10, which serves as both an in-core and an out-of-core fuel transfer device, is moved to the innermost side of the core during fuel exchange, the small rotating plug 7 rotates 180 degrees to the position shown in FIG. 3. That is, the core upper structure 9 and the through hole 1
0 has been exchanged compared to the position in FIG. Since it is necessary to rotate the large rotating plug 4 in order to use the core superstructure 9, the circumscribed circle 13 centered on the rotating shaft 5 that is in contact with the core superstructure 9 located on the outside is the same as the inner diameter of the reactor vessel 2. This is the minimum size, and the inner diameter cannot be made smaller than this. In addition, in order to transfer fuel inside the reactor and to transfer fuel outside the reactor, the transfer device must be replaced each time, and at the time of fuel replacement, the activated fuel passes through the through hole 10. A larger and more sufficient shield is required than in the case where only the in-core fuel transfer device is installed around the reactor, and the through hole 10 itself is also large, making the arrangement complicated and narrow. Furthermore, the time required for handling fuel cannot be reduced to a certain level due to the time required to replace the fuel transfer device, which is not satisfactory.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a dual rotary reactor main body lid that can further reduce the size of the reactor vessel and shorten the time required for handling fuel during refueling.

Next, the present invention will be explained with reference to an embodiment shown in FIGS. 4 to 6 of the accompanying drawings.

In FIG. 4, the large-rotation plug 4 includes a small-rotation plug 7 having a rotation center 6 offset from the rotation center 5 by a predetermined eccentric amount. The large rotary plug 4 is also provided with a first through hole 14 for an extra-core fuel transfer device. The center axis 15 of the first through hole 14 is the maximum pitch circle 16 of the in-core fuel rack 12 (see FIG. 1).
It is located above.

The small rotation plug 7 includes a core upper structure 9 having a central shaft 8 and a second through hole 18 for an in-core fuel transfer device having a central shaft 17. During reactor operation, the small rotating plug 7 is in the position shown in FIG. 4. In this position, the central axis 8 of the core superstructure 9 is spaced apart from the rotation center 6 by a distance equal to the eccentricity described above, so that the central axis 8 of the core superstructure 9 coincides with the rotation axis 5 of the large rotating plug 4. Thus, the core superstructure 9 is located at the center of the reactor vessel 2 . The second through hole 18 for the in-core fuel transfer device of the small-rotation plug 7 has its central axis 17 spaced a distance equal to the distance from the rotation center 6 of the small-rotation plug 7 to the rotation center 5 of the large-rotation plug 4, that is, as described above. separated from the center of rotation 6 by a distance equal to the amount of eccentricity of be in the position. When the angle θ exceeds 90°, the structure of the small rotation plug 7 becomes complicated and narrow. The desired range is
The angle is between 65° and 90°.

The operation of the double rotary plug reactor body cover configured as described above is as follows.

In order to extract the spent fuel from the core 1 and transfer it to the in-core fuel rack 12 for refueling, an in-core fuel transfer device is installed in the second through hole 18.
The fuel transfer device is operated while changing the position of the fuel transfer device by suitably combining the rotations of the large rotation plug 4 and the small rotation plug 7. For example, in order to extract fuel from the center (innermost part) of the core, the small rotating plug 7 is rotated 180°-θ° counterclockwise as shown by arrow 19' to move the second through hole 18 to the center of the core (the innermost part). Figure 5). Next, the fuel is grabbed by the fuel transfer device and pulled out, and the small rotation plug 7 is rotated 180 degrees, that is, further θ degrees clockwise from the original position as shown by the arrow 20, to move the fuel onto the fuel rack 12 (see Fig. 6). ), the fuel is unloaded and inserted into the fuel rack 12 at that location. As is clear from FIG. 5, when the second through hole 18 for the in-core fuel transfer device comes to the innermost side,
The core upper structure 9 is connected to the rotation center 6 from the second through hole 18.
The minimum inner diameter limit of the furnace vessel 2 (Fig. 1) is
A circumscribed circle 19 is centered on the rotation center 5 of the large rotating plug and touches the core upper structure 9. This circumscribed circle 1
9 is considerably smaller than the circumscribed circle 13 in FIG. 3, and it can be seen that the inner diameter of the furnace vessel, and hence the outer diameter of the furnace vessel, can be made considerably smaller.

To transfer the spent fuel stored in the in-core fuel rack 12 to the outside of the reactor, the out-of-core fuel transfer device is inserted into the first through hole 14 and operated to pull up the fuel and transfer it to the outside of the reactor. do. The position of the extra-core fuel transfer device can be changed by rotating the large rotary plug 4. A first through hole 14 is provided at a position where the extra-core fuel transfer device is inside the minimum inner diameter of the reactor vessel, that is, the circumscribed circle 19.
Of course, it is necessary to provide

According to the double rotary reactor main body cover of the present invention having the above-described structure, the diameter of the reactor vessel can be made smaller than that using a conventional double rotary plug, and the entire equipment is extremely small and the cost is reduced. It can be done cheaply. Further, the in-core fuel transfer device and the out-of-core fuel transfer device are provided independently, and dedicated first and second through holes 14 and 18 are respectively provided at positions where they can be placed at positions where they do not interfere with each other. . Therefore, there is no need to replace the in-furnace and out-of-furnace fuel transfer devices, saving time for removal and installation.
Fuel exchange work time is shortened. Furthermore, since the connection position of the extra-core fuel transfer device to the large rotating plug is constant, the device can be simplified and the working time can be shortened. Furthermore, since the large extra-core fuel transfer device is attached to the large rotation plug 4 and the relatively small in-core fuel transfer device is attached to the small rotation plug 7, equipment can be advantageously arranged on the small rotation plug, and the structure is simple. become.

According to the present invention, the results of trial calculation of the dimensions of each part were as follows. In other words, the following common design conditions were adopted: large rotating plug diameter 9.4 m, small rotating plug diameter 5.8 m, large/small plug eccentricity 1.5 m, core upper structure diameter 2.4 m, maximum pitch circle diameter for in-core fuel rack 6.0 m, and conventional technology. When the configuration shown in Figures 1 to 3 was used, the standard inner diameter of the reactor vessel was 8.4 m and the small rotation plug through hole diameter was 1.0 m, but with the configuration of the present invention, θ was set to 65°. In this case, the standard inner diameter of the reactor vessel was 7.6 m, and the diameter of the small rotating plug through hole was 0.6 m.

When θ is set to 90° in the configuration of the present invention, the standard value of the inner diameter of the reactor vessel is 6.6 m.

Here, the reactor vessel inner diameter reference value means the maximum circumscribed circle diameter of the reactor core upper structure.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view of a reactor vessel with a conventional double rotary reactor body lid, Figures 2 and 3 are schematic plan views of the double rotary plug shown in Figure 1, and Figure 4 is a main A schematic plan view showing the double rotary reactor main body cover of the invention in the reactor operating position, FIG. 5 is a schematic plan view showing the double rotary reactor main body cover of the invention in the reactor operating position, with the through hole for the in-reactor fuel transfer device in the double rotary reactor main body cover shown in FIG. 4 being located at the innermost side of the core. FIG. 6 is a schematic plan view showing a state in which the through hole for the in-reactor fuel transfer device of the double rotary reactor main body cover in FIG. 4 is located above the in-reactor fuel rack. It is. 4... Large rotating plug, 5... Center of rotation of the large rotating plug, 6... Center of rotation of the water rotating plug, 7...
Small rotating plug, 8... Central axis of upper core structure, 9
... Upper core structure, 14 ... Through hole of the extra-core fuel transfer device, 15 ... Central axis of the through hole of the extra-core fuel transfer device, 17 ... Central axis of the through hole of the in-core fuel transfer device, 18 ... ...Through-hole of the in-core fuel transfer device.

Claims (1)

[Scope of Claims] 1. A large rotation plug having a rotation center, a small rotation plug provided within the large rotation plug and having a rotation center eccentric from the rotation center by a predetermined amount of eccentricity, and a small rotation plug provided within the large rotation plug; and an upper core structure provided on the small rotating plug so as to have a central axis spaced apart from the center of rotation of the small rotating plug by a distance equal to the eccentricity. The small rotation plug is provided with a through hole for an in-core fuel transfer device, and the center axis of the through hole for the in-core fuel transfer device is aligned with the center axis of the upper core structure and the rotation center of the small rotation plug. A position that is angularly displaced by an angle θ not exceeding 90° from the center of rotation of the small rotation plug with respect to the extension of the straight line connecting them, and is spaced from the center of rotation of the small rotation plug by a distance equal to the eccentricity. A double rotary reactor main body lid characterized by: 2. The large rotating plug is provided with a through hole for an extra-core fuel transfer device, and the center axis of the through hole for the extra-core fuel transfer device is separated by a distance equal to the radius of the maximum pitch circle of the in-core fuel rack in the reactor vessel. The double rotary reactor main body lid according to claim 1, characterized in that the lid is spaced apart from the center of rotation of the large rotating plug. 3. The double rotary reactor main body lid according to claim 1, wherein the angle θ is 65° to 90°.