JPS6051676B2 - Blade guide for nuclear reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blade guide used as a guide for inserting fuel assemblies or control rods during fuel exchange or control rod scram tests in boiling water nuclear reactors.

The control rods used in boiling water reactors, which have a cross-shaped cross section, are supported by the outer surface of the channel box of the fuel assembly that exists on all four sides of the control rods. If the four surrounding fuel assemblies are removed, such as during a scram test, the control rod will no longer be able to stand on its own.

Therefore, a blade guide is inserted to support the control rod. Traditional blade, LMU KJhi
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Le J, -le! A pair of guide bodies are connected to each other at their upper ends by a fixed connecting body, and there is no connection at all on the lower side. When moving the guide body, the lower sides of each guide body swing in random directions relative to each other, resulting in extremely poor workability.
There have been cases in which the fixed connection body is subjected to excessive force, leading to damage. In particular, fuel loading work is a remote operation under water, and the work conditions are extremely harsh.As mentioned above, if the blade guide is not easy to operate, the work requires a long time, which increases the radiation exposure of the workers. It was the cause of this. The present invention was made based on the above circumstances, and its purpose is to provide a blade guide that can prevent undesired movement of guide bodies relative to each other during underwater transportation, etc., and in particular, greatly improves operability underwater. It's about doing. The present invention will be described below based on an illustrative embodiment.

In the figure, 1 indicates a blade guide, and 1a and la indicate a pair of guide bodies. The guide bodies 1a and 1a are each formed into an elongated shape having substantially the same shape as the boiling water reactor fuel assembly A shown in FIG. 2, 2 are lower tie plates, and these lower tie plates 2, 2 have a shape that can be attached to a lower core grid in a reactor pressure vessel (not shown).

Further, the guide bodies 1a, 1a are connected to each other by a fixed connecting body 3 at their upper ends. This fixed connection body 3 is made by connecting two plate materials 4, 4 with bolts 5, etc., and is provided at the upper end of the guide bodies 1a, 1a between these plate materials 4, 4. By sandwiching the handles 6, 6, the guide bodies 1a, 1a are connected and fixed to each other. Further, a handle 7 for hanging is attached to the fixed connecting body 3. In addition, the guide bodies 1a, 1
A is provided with a movable connector 10 below the fixed connector 3.

The movable coupling body 10 is fitted to the guide bodies 1a, 1a so as to be able to move freely along the longitudinal direction of the guide bodies 1a, 1a, that is, in the vertical direction, and is moved to the lower limit position by the weight of the movable coupling body itself. That is, in this embodiment, it falls to a position where it hits the lower tie plate 2 and stops. Moreover, this moving coupling body 10 is
As shown in FIG. 3, when the blade guide 1 is inserted into the upper core grid B in the reactor pressure vessel, it can move to the upper end of the blade guide bodies 1a, 1a. Furthermore, a groove 11 is formed on the side surface of the movable connector 10 to avoid the spacing pad a1 attached to the upper part of the fuel assembly A. In addition, fuel assembly A
At the top of the button, there is a channel fastener A next to the pad a1.
2 is provided protrudingly. The blade guide 1C'i configured as described above is used for loading and unloading the fuel assemblies A in the core lattice B, for example, during fuel exchange.

That is, first, two diagonally adjacent fuel assemblies A and A are extracted, and then the blade guide 1 is inserted into the space after the extraction. At this time, the blade guide 1 is transported with the handle 7 suspended by the gripping tool of the automatic fuel exchanger, but during the transport, as shown in FIG. Guide body 1a,
Since the guide bodies 1a are located at the lower end of the guide body 1a, the movable connector 10 and the fixed connector 3 integrate the guide bodies 1a, 1a together. Therefore, the guide bodies 1a, 1a are transported integrally without mutually moving in separate directions. Then, when the guide bodies 1a, 1a are inserted into the upper core lattice B, the movable coupling body 10 hits the upper end surface of the upper core lattice B, as shown in FIG. Move to the top. When the insertion of the blade guide 1 is completed in this way, remove the remaining fuel assemblies A, A shown by imaginary lines in FIG. 4, insert a new fuel assembly, and then insert the blade guide 1. Pull it out. Even when the blade guide 1 is pulled out in this way, the two fuel assemblies A, A are located diagonally within the core lattice B, so they are maintained in a correctly upright state without falling over. Then, new fuel assemblies A, A are inserted into the space left after the blade guide 1 has been extracted, and the replacement of the four fuel assemblies A is completed. As described above, according to the blade guide 1 of this embodiment, during the transfer of the blade guide 1, the movable coupling body 10 is located at the lower end of the guide bodies 1a, 1a due to its own weight, and the guide body 1
Since the guide body 1a is interconnected with the guide body 1a, even if it receives large fluid resistance in the lateral direction, especially during underwater transfer, the guide body 1a
, 1a can be prevented from moving independently in irregular directions, and the blade guide 1 can be correctly inserted into the upper core lattice B. Furthermore, as mentioned above, since the guide bodies 1a, 1a are prevented from varying, unreasonable twisting force is not applied to the fixed connecting body 3 as in the conventional case, and damage to the blade guide 1 is prevented. . In addition, in the case of this embodiment, since the movable coupling body 10 covers the upper end portions of the guide bodies 1a, 1a, the insertion of the fuel assembly A,
At the time of loading, the movement of the channel fastener A2 of the fuel assembly A is smoothly guided by the movable coupling body 10, and damage problems due to mutual interference between the channel fastener A2 and the handle 7 will hardly occur. There are also advantages. Although this embodiment is constructed as described above, in carrying out the present invention, the shape of the movable coupling body can be modified in various ways.In short, the movable coupling body can be moved in the longitudinal direction of the guide body. The present invention is not limited to the embodiments as long as the guide bodies are configured to connect with each other.

As explained above, according to the present invention, the guide bodies are connected to each other by a movable coupling body that is slidable in the longitudinal direction of the guide bodies and moves to the upper end of the guide bodies when the guide bodies are inserted into the upper core lattice. Because they are connected together, when transferring the blade guide between the fuel storage pool and the core lattice, it is possible to prevent the guide bodies from swinging in disorderly directions with respect to each other, and the guide bodies can be integrated into each other. Can be transported.

Therefore, the blade guide can be easily handled, especially underwater, and insertion into the core grid can be performed quickly and reliably. Therefore, the time required to work inside the reactor can be shortened, and the amount of radiation exposure of workers can be reduced. Moreover, since the guide bodies are prevented from moving unevenly during transportation, there are various practical benefits such as preventing strain on the connecting part that connects the upper ends of the guide bodies, and preventing damage to this connecting part. It has excellent effects.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a perspective view of the blade guide, FIG. 2 is a partially sectional front view, FIG. 3 is a front view of the blade guide inserted into the core lattice, and FIG. 4 is a front view of the blade guide. is a plan view of the same, and FIG. 5 is a perspective view showing the fuel assembly. DESCRIPTION OF SYMBOLS 1... Blade guide, 1a... Guide body, 10... Moving coupling body, A... Fuel assembly, B... Upper core lattice.

Claims (1)

[Claims] 1 A pair of elongated guide bodies that have almost the same shape as the fuel assembly are connected and fixed to each other at their upper ends, and these guide bodies are slid together in the longitudinal direction of the guide bodies below this connection part. They are connected by a freely movable connecting body, which can fall to the lower limit position of the guide body due to its own weight, and when the guide body is inserted into the upper core lattice, it contacts the upper core lattice and the guide body A nuclear reactor blade guide that moves to the upper end.