JPS6346878Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a single-rotation plug fixed arm type nuclear reactor refueling machine.

In particular, this type of refueling machine used in liquid metal cooled nuclear reactors must have a movable mechanism as simple as possible, since the movable parts inside the reactor are exposed to an atmosphere containing liquid metals, such as sodium and sodium vapor. It is desired that the fuel exchanger main body can be easily pulled out of the reactor during reactor operation, and that the overall size of the fuel exchanger be small so that the space it occupies on the rotating plug can be reduced.

On the other hand, a so-called pantograph type fuel exchanger is known in which the offset arm supporting the gripper is foldable. An outline of the structure of such a fuel exchanger is shown in FIG. In the figure, 1 is the upper rotating plug of the reactor vessel, and the fuel exchanger is a hold-down shaft 2 that passes through the rotating plug 1 and is suspended into the reactor.
The main equipment components are a rotational drive mechanism 3 for the entire fuel exchanger connected to a hold-down shaft, and a main body 4 of the fuel exchanger that is raised and lowered by a hoisting device (not shown) within the hold-down shaft. A gripper 6 is supported at the tip of the main body 4 via a pandagraph type offset arm 5 of a folding mechanism that extends in and out from the main body laterally. In addition, 7 is a rotation device for the entire fuel exchanger connected to the hold-down shaft 2, which is a hold-down drive mechanism, 8 is a casing with a door valve attached to the top and also serves as a shield body, 9 is a hold-down shaft plug, and 10 is a hold-down drive mechanism. The down arm 11 is a drive device that opens and closes the claws of the gripper 6 and moves the offset arm 5 in and out between the solid line and broken line positions.

As is well known, such a pantograph type refueling machine is positioned at a predetermined refueling position in the reactor core by the interlocking rotation operation of a rotary plug 1 and a hold-down shaft 2, and the refueling machine main body 4 is operated at this position. Then, the fuel is extracted and loaded. When the fuel exchange work is completed, the offset arm 5 is folded and the gripper 6 is stored in the main body 4, and then the main body 4 is pulled out of the furnace and stored in a special cask, and then the main body 4 is stored in a special cask until the next fuel exchange is performed. It will be moved to another location and stored. In other words, in the conventional structure, when the main body 4 is pulled out of the furnace, the offset arm 5 and the gripper 6 are moved so that they do not get in the way of the pantograph type offset arm 5 and gripper 6 passing through the narrow passage in the upper opening of the hold down shaft 2. The arm 5 has a foldable structure, but this not only makes the mechanism of the main body, especially the part inserted into the furnace, extremely complicated, but also has many movable mechanical parts that operate in the sodium atmosphere inside the furnace. Since there is a risk of non-operation due to adhesion and solidification, maintenance such as sodium cleaning is time consuming and maintenance management is troublesome. Furthermore, since the folding offset arm is large in size due to its special mechanism, it has drawbacks such as the difficulty of providing sufficient mechanical strength within the limited space of the main body.

This invention was developed in consideration of the above points, and its purpose was to eliminate the drawbacks of conventional fuel exchangers and to provide a single-rotation plug fixed arm type fuel exchanger with a simple structure and high reliability. be.

This purpose was achieved through the use of a rotary containment tube that is suspended and supported in the furnace through a rotary plug, and is integrally formed with a cylindrical lower part eccentric to the cylindrical upper part; a fuel exchanger main body plug that is fitted into the upper open end of the storage pipe and serves as a plug body with a main body insertion hole;
This is achieved by constructing an offset arm with a gripper supported at its tip that protrudes to the side, and an independently rotating fuel exchanger body that fits into the body insertion hole of the plug and is suspended into the furnace. be done.

Embodiments of this invention will be described below in detail based on the drawings.

In FIG. 2, first, instead of the hold-down shaft 2 in FIG. 1, a containment pipe 12, which is integrally formed with a cylindrical lower part eccentric to the cylindrical upper part, penetrates the rotating plug 1 and enters the furnace. It is suspended and supported, and an offset arm is attached to the top of this storage pipe 12.
An overall rotational drive device 3 is connected to the gripper and a hold-down shaft that accommodates the fuel exchanger main body, which rotates the entire unit. On the other hand, the storage pipe 12
A fuel exchanger main body plug 13 is fitted into the upper opening of the fuel exchanger main body 4, and a fuel exchanger main body 4 is rotatably fitted into a main body insertion hole 14 formed in the main body plug 13. Here, the exchanger main body 4 is the main body plug 1
It is attached eccentrically from the center of 3. Further, the main body 4 is provided with an offset fixing arm 15 that protrudes laterally from the main body.
A gripper 6 is supported at the tip of the gripper 6. This offset fixed arm 15 is different from the folding type of the conventional machine, and is a simple arm that always sticks out to the side, and its base is attached to the drive device 1 on the top of the main body.
Ball screw 1 for lifting and lowering the gripper operated from 1
It is screwed to 6. Further, a hold-down arm 17 that also serves as a guide for the gripper 6 is attached to the tip of the main body 4, and a hold-down drive mechanism 7 is connected to the upper part of the main body 4. In addition, a main body rotation mechanism 18 for independently rotating the main body within the main body plug 13 is installed on the drive device 11 at the top of the main body. Note that 19 is casing 8
20 is a storage pipe plug.

To perform a fuel exchange in the above configuration, first, the position for fuel exchange is determined by rotating the rotary plug 1 and the storage tube 12, and then the main body 4 is lowered slightly by the hold-down drive mechanism 7 to perform a hold-down operation. The arm 17 suppresses floating of the surrounding fuel around the replacement fuel. Next, the gripper 6 is operated downward, and when the gripper reaches the fuel, the claws are opened to grasp the fuel, and the ball screw 16 is operated to pull out the spent fuel. Also, loading new fuel into the core is performed in the reverse order of the withdrawal operation.

Now, when the fuel exchange work is completed and the fuel exchanger main body 4 is to be taken out of the furnace, the main body rotating mechanism 18 is first driven so as to move the gripper 6 from the fuel exchange position shown in the figure to the position shown by the broken line. 4 within the main body insertion hole 14 of the main body plug 13. At this time, as mentioned earlier, the main body 4 is connected to the main body plug 1.
3 and is located eccentrically from the center of the storage tube 12, and the storage tube itself is also made in advance so that the lower part of the storage tube is offset from the upper part in accordance with the amount by which the exchanger main body is eccentric with respect to the main body insertion hole. Moreover, since the inner diameter is determined to correspond to the offset amount of the gripper 6, the gripper 6 will not interfere with the inner wall of the storage pipe 12 at the position shown by the broken line. Next, a cask dedicated to the main body is connected to the top of the door valve 19, and after opening the door valve, the main body 4 and the main body plug 13 are removed from the storage pipe 12 together with the main body plug 13 using the lifting device of the dedicated caster, and lifted up and housed in the dedicated caster. .

As mentioned above, according to this invention, the main body of the fuel exchanger is supported via the main body plug at a position eccentric from the center of the storage pipe, and the main body itself is configured to be able to rotate independently. Therefore, the offset arm can be passed through the narrow opening of the storage pipe without having to configure the offset arm in a foldable manner as in the past.
The main body of the fuel exchanger can be pulled out of the furnace.
In addition, since the gripper is installed eccentrically with respect to the main body, the effective eccentricity of the gripper with respect to the rotation center of the storage pipe is the sum of the eccentricity of the main body with respect to the storage pipe and the eccentricity of the gripper with respect to the main body. The required amount of offset necessary for positioning for refueling can be obtained even by using an offset fixing arm that is shorter in size than the offset arm in conventional machines. Furthermore, the shorter the offset arm, the less moment load will be applied to the offset arm and main body when lifting fuel, which will be advantageous in terms of strength. In addition, the offset fixed arm, which is not a folding mechanism, has a simpler structure and fewer moving mechanical parts than conventional models, and is therefore less susceptible to adhesion and solidification of sodium or sodium vapor when exposed to the sodium atmosphere in the furnace. It is highly reliable, with an extremely low risk of it becoming inoperable even when it is used, and is highly safe.It is small overall, and the mechanism of the part inserted into the furnace can be simplified, and it also improves mechanical strength and maintainability. A single rotation plug fixed arm type nuclear reactor refueling machine can be provided.

[Brief explanation of drawings]

FIGS. 1 and 2 are sectional views of a conventional fuel exchanger and an embodiment of this invention, respectively. DESCRIPTION OF SYMBOLS 1...Rotating plug, 3...Fuel exchanger whole rotation drive device, 4...Fuel exchanger body, 6...Gripper, 12...Storage pipe, 13...Fuel exchanger body plug, 14...Body insertion hole, 15 ...Offset fixed arm, 18...Body rotation mechanism.

Claims (1)

[Scope of utility model registration request] A rotary storage pipe is formed integrally with the cylindrical lower part being eccentric to the cylindrical upper part, and is suspended and supported in the furnace through the rotating plug, and the main body insertion hole is made at a position eccentric from the center. A fuel exchanger main body plug is fitted and installed in the upper opening end of the storage pipe serving as a plug body, and an offset fixing arm supporting a gripper at the tip is provided to protrude laterally, and is fitted into the main body insertion hole of the plug. A single-rotation plug fixed arm nuclear reactor refueling machine, characterized in that it consists of an independently rotating refueling machine body suspended into the reactor.