JPH0576598B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fuel exchange machine for exchanging fuel assemblies loaded in a nuclear reactor, and more specifically, to a fuel exchange machine for exchanging fuel assemblies loaded in a nuclear reactor. This invention relates to a fuel exchanger that can be made smaller and shorter, without requiring a long operation stand as seen in the figure.

<Prior Art> In order to exchange a fuel assembly loaded in a nuclear reactor such as a fast reactor, a fuel exchange machine as schematically shown in FIG. 4 has conventionally been used. That is,
A fuel exchanger housing 3 suspended from a rotary plug 2 of a reactor vessel 1 extends to the vicinity of the reactor core 4, and a fuel exchanger main body 6 has a gripper 5 attached to its tip that can be raised and lowered by a long rod-shaped gripper lifting device.
is supported by a rotary drive device 7 and housed within the housing 3. The gripper 5 of this refueling machine combines the rotational operation of the rotary plug 2 and the rotational operation of the refueling machine main body 6 by the rotational drive device 7, so that an arbitrary core component in the reactor core (in this specification, (simply referred to as a fuel assembly). By positioning the gripper 5 directly above a predetermined fuel assembly and raising and lowering the elongated rod-shaped gripper lifting device of the fuel exchanger main body 6, the fuel assembly can be pulled out and inserted by the gripper. It's summery.

<Problems to be Solved by the Invention> However, in the conventional fuel exchanger as described above, since the fuel exchanger body 6 has a long metal housing structure, it has the following drawbacks.

In order to insert and extract the in-core fuel assembly and to install and remove the fuel exchanger main body 6, an operating frame 8 that is equal in length or longer than the fuel exchanger main body is required on the rotary plug 2. For example, in the case of the experimental fast reactor "Joyo", a height of approximately 12.5 m is required from the top surface of the rotating plug 2 to the top of the operating stand 8. (In the actual refueling machine of “Joyo”, the 4th
It does not have the rotary drive device 7 shown in the figure, and the gripper 5 is installed at the tip of the fuel exchanger main body 6 in a straight line therewith, but the height from the top surface of the rotary plug 2 to the top of the operating stand 8 is is about 12.5m
It is becoming. ) Since the main body 6 of the fuel exchanger and the operation stand 8 are heavy objects, earthquake resistance restrictions on the installation part become severe.

For maintenance of the fuel exchanger body,
Because it is long and heavy, workability is extremely poor.

Because the refueling machine has a long overall length due to its function, it is necessary to increase the height of the reactor containment vessel that houses it.

In order to secure the reactor boundary, a shaft sealing device for the fuel exchanger body is required, and the long sliding length makes it difficult to maintain the shaft sealing mechanism.

SUMMARY OF THE INVENTION Therefore, the present invention has been made with the object of providing a fuel exchanger whose main body can be made extremely short, thereby overcoming the drawbacks of the prior art described above.

<Means for Solving the Problems> The fuel exchanger according to the present invention has a structure in which the gripper is raised and lowered by raising and lowering the gripper lifting device in the form of a long rod, as in the past, and instead uses a windable chain, a metal tape, Another feature is that the gripper is raised and lowered by winding or lowering a wire rope or the like (in this specification, these are collectively referred to as suspension means).

That is, a cylindrical casing is erected above the rotating plug of the reactor vessel, and a fuel assembly is mounted at the tips of at least one pair of suspension means that can be wound up by a suspension means drive device provided on the upper part of the cylindrical casing. A gripper for gripping is attached, and this gripper is passed through the cylindrical casing, and further through the rotating plug, and suspended to the vicinity of the reactor core inside the reactor vessel. Lifting and lowering of the gripper and control of the gripper gripping mechanism can be performed by hoisting and lowering the suspension means.

Further, by placing a weight on the upper part of the gripper, it is possible to apply a pushing force when inserting the fuel assembly into the reactor core.

<Embodiments> The present invention will be described in detail below with reference to preferred embodiments shown in the drawings.

FIG. 1 is a schematic explanatory diagram for clarifying the basic features of the device of the present invention and the effects obtained thereby in comparison with the conventional device shown in FIG.
Components that are the same as those in FIG. 4 are given the same reference numerals and their explanations will be omitted. As can be seen from FIG. 1, in the fuel exchanger 10 of the present invention, unlike the conventional device shown in FIG. The casing 11 may be erected. A pair of suspension means, for example a drive device 13 for the chain 12, are arranged in the upper part of the casing 11, so that the chain can be hoisted and lowered. chain 12
A gripper 14 is attached to the tip of the reactor, and the gripper 14 is passed through the casing 11, penetrates the rotary plug 2, and is suspended near the reactor core 4.

A weight 15 is placed on the gripper 14, and the weight 15 can apply a pushing force when inserting the fuel assembly gripped by the gripper into the reactor core 4.

The device 10 of the present invention shown in FIG. 1 having the above configuration
Compared to the conventional device shown in FIG.
It can be seen that quantification can be achieved.

FIG. 2 explains the details of the fuel exchanger 10 of the present invention, in which a chain drive device 13 provided on the upper part of the cylindrical casing 11 has a pair of drums 13a and 13b inside. These drums can raise and lower the gripper 14 by rotating in the direction of hoisting and lowering the chains 12a and 12b at the same time.Furthermore, the chain 12a can be fed out from one drum 13a, and the corresponding amount of the chain 12b can be fed out from one of the drums 13a. By winding the length with the other drum 13b, a drum 21 inside the gripper 14, which will be described later, can be rotated to open and close the claws 23 of the gripper.

As shown in FIG. 3, the inside of the gripper 14 includes a drum 21, an actuator 22 that moves up and down as the drum rotates, and claws 23 that open and close by lever action by the top and bottom of the actuator 22.
Rotation of the drum 21 can be performed by winding up the chain 12a extending through the weight 15 and lowering the chain 12b. That is, by rotating the pair of drums 13a and 13b of the chain drive device 13 in opposite directions, the gripper 14 moves up and down as a whole along with the weight 15 while the opening of the claws remains the same. Further, by rotating the drums 13a and 13b in the same direction, the opening degree of the gripper claws 23 can be changed while the vertical positions of the gripper 14 and weight 15 remain unchanged.

Referring again to FIG. 2, the reference numeral 16, illustrated in a simplified manner with solid lines, indicates a case housing plug-side door valves 16a, and these plug-side door valves and their cases are also used in conventional nuclear reactors as well as rotating plugs 2. It is installed above. Cylindrical casing 1 in this invention
1 can be erected on the plug-side door valve case 16 via a flange portion using a bolt tightening mechanism 11b or the like.

Inside the cylindrical casing 11, the chain 12 is wound up and the gripper 14 and weight 15 can be accommodated therein. Cylindrical casing 1
In order to ensure the confidentiality of the inside of the casing when the cylindrical casing is removed from above the rotary plug with the gripper and weight housed in the fuel exchanger side door valve 11a, the cylindrical casing is provided with a door valve 11a on the fuel exchanger side.

In the illustrated embodiment, a gripper 14 suspended by a chain 12 connects a holddown tube 30 typically installed in conventional refueling machines.
It is also used as a guide tube to prevent the weight 15 from swinging. That is, when the hold-down pipe 30 grips and pulls out the desired fuel assembly 40 with the gripper 14,
This is to prevent the surrounding fuel assemblies 41 and 42 from floating up, and the power cylinder 31
By slightly moving the hold-down pipe 30 up and down, the lower end 30a of the hold-down pipe knocks off the surrounding fuel assemblies 41, 42, and removes these fuel assemblies 41, 42 along with the desired fuel assembly 40.
can be prevented from being pulled out. In this invention, the gripper 14 and the weight 15 are suspended in such a hold-down pipe 30, and the gripper 14 and the weight 15 also serve as a guide pipe when the gripper is raised and lowered, thereby making it possible to prevent the gripper and the weight from swinging. . In order to facilitate handling when the hold-down and gripper guide tube 30 is taken out for maintenance or the like, it is desirable that the tube 30 be divided into upper and lower sections by the bolt tightening mechanism 30b.

Next, the operation and use of the fuel exchanger 10 of the present invention will be explained. When pulling out a fuel assembly 40 from the core 4, the gripper 14 is positioned above the desired fuel assembly 40 by rotation of the rotary plug 2, and the drum 13 in the chain drive device 13 is pulled out.
a and 13b are rotated to lower the gripper 14 and fit the gripper tip to the top of the fuel assembly 40. Furthermore, the opening degree of the chain pawl 23 is adjusted by operating the drum of the chain drive device 13.
ensure that it engages with the hook on the top of the fuel assembly 40. In this state, the drums 13a, 1
The gripper 14 is raised by the rotation of the gripper 3b, and the fuel assembly 40 gripped by the gripper 14 can be pulled out. On the other hand, when inserting the fuel assembly gripped by the gripper 14 into a predetermined position in the reactor core 4, the above-mentioned operation may be performed in reverse. During this insertion, the force of pushing the fuel assembly can be applied by the load of the weight 15.

In addition, normally the cylindrical casing 11 forms the reactor boundary, but the gripper 14 and the weight 1
5 is housed in the cylindrical casing 11, and when the bolt tightening mechanism 11b is separated and carried in this state, the inside of the cylindrical casing can be kept in a confidential state by closing the fuel exchanger side door valve 11a. At this time, the reactor boundary is formed by closing the plug-side door valve 16a.

Although not shown, it is desirable that the drums 13a and 13b of the chain drive device 13 be provided with a stroke detection mechanism and a load detection mechanism in order to ensure safety and reliability of operation. It is desirable to provide an ultrasonic or electromagnetic grasping detection mechanism for accurately detecting whether or not the fuel assembly is being grasped. All of these detection mechanisms are conventionally known.

The experimental fast reactor "Joyo" requires a maximum pushing force of 500 kg when inserting the fuel assembly into the reactor core. Therefore, in this invention,
When trying to secure a pushing force of 500 kg using the weight 15, the weight dimensions are as follows. When the diameter of the gripper guide tube 30 shown in FIG. 2 is set to 160 mm, the diameter of the weight may be set to 150 mm by ensuring a clearance for the weight 15 to be able to move up and down within the gripper guide tube. When lead (specific gravity at 200°C: 11.4) is used as the material of the weight, the height L of the weight is approximately 2.5 m from the following formula.

[(π×1.5 ² )/4]×11.4×L=500 In reality, a through hole for a suspension means such as a chain is drilled in the weight, and the entire weight is covered with a stainless steel outer skin. However, these were ignored in the calculations.

The height of the refueling machine according to the present invention when using a weight having such dimensions is as shown in FIG. That is, A in FIG. 2 corresponds to the height of the chain drive device 13, which can be about 1 m. In order to accommodate the weight 15 and gripper 14 in this part after the fuel exchange work is completed, B is a weight (2.5 m).
and Gritspa (0.5m) and the total height (3m).
C is the height of the existing door valves 11a, 16a, bolt tightening mechanism 11b, etc., and is the same as before.
Approximately 1.8m is sufficient. Therefore, the total height of A, B, and C is 5.8 m. Comparing this figure with the conventional refueling machine height of 12.5 m shown in Figure 4 for the experimental fast reactor "Joyo", it can be seen that it can be shortened to about 1/2.

<Effects of the Invention> Since the fuel exchanger of the present invention has the above-described configuration, it can achieve many excellent effects as described below.

b) Instead of the metal housing method used in conventional fuel exchangers, this system uses a suspension means such as a windable chain, metal tape, or wire rope, which allows for an extremely short structure, allowing for the insertion and removal of fuel assemblies. stroke,
In addition, a long operating stand or casing corresponding to the stroke required for storing the fuel exchanger main body becomes unnecessary.

(b) Due to the reason (a) above, the fuel exchanger is made smaller and lighter overall, and the seismic restrictions on the installation side are relaxed.

C. Currently, the height of the fuel exchange machine determines the height of the reactor containment vessel, so the height of the containment vessel can be lowered for the reason of (a) above, and it is possible to significantly reduce the amount of material due to the reason of b) above. Become.

Because the gripper and the gripper drive means, such as a chain, can be easily separated, concerns regarding maintenance of the transmission system within the housing associated with conventional refueling machines are eliminated.

E. The weight serves as a shielding function for radiation from the fuel during fuel exchange, and shielding the cylindrical casing that is the gripper storage container is simple because it is only necessary to take into account the radioactive sodium that adheres to it.

Since the entire gripper body can be stored inside the cylindrical casing, a sealing mechanism is not required during fuel handling.

G. The hold-down pipe of the fuel assembly installed in conventional fuel exchange machines can be used to prevent the gripper from swinging.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a fuel exchanger according to the present invention;
FIG. 2 is an explanatory diagram of a preferred embodiment of the fuel exchanger of the present invention; FIG. 3 is a partially cutaway explanatory diagram of the gripper and weight portion of FIG. 2; and FIG. 4 is a schematic explanatory diagram of a conventional fuel exchanger. be. 1... Reactor vessel, 2... Rotating plug, 4...
Core, 10... Fuel exchange machine, 11... Tubular casing, 12... Suspension means (chain), 13...
Suspension means (chain) drive device, 14... gripper, 15... weight, 40... fuel assembly.

Claims (1)

[Claims] 1. A cylindrical casing is erected above the rotating plug of the reactor vessel, and the fuel assembly is held at the tips of at least one pair of suspension means that can be wound up by a suspension means drive device provided at the top of the cylindrical casing. attaching a gripper to the reactor, passing the gripper through the cylindrical casing, further penetrating the rotating plug, and suspending the gripper to the vicinity of the fuel assembly in the core in the reactor vessel;
By operating the suspension means, the gripper can be raised and lowered and the gripping mechanism of the gripper can be controlled, and a weight is placed on the upper part of the gripper, so that when the gripper inserts the fuel assembly into the core. A fuel exchange machine characterized by being able to apply pushing force.