JPH0679072B2 - Refueling device for nuclear reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention is suitable for a refueling apparatus for a nuclear reactor, particularly for a fast breeder reactor using opaque and chemically active liquid sodium metal as a coolant. The present invention relates to a fuel exchange device.

<Prior Art> Fuel exchange devices in sodium-cooled fast reactors, which cannot be visually operated and are not allowed to be opened to the atmosphere by removing the lid of the reactor vessel, are roughly classified into the operation method under the shielded plug and the hot cell. The former operation method under the shielded plug is further classified into a single rotation plug type, a double rotation plug type and the like. In the single-rotation plug type, the shielding plug that shields the radiation and heat from the core is a large circular fixed plug,
It consists of a small circular rotary plug with its center of rotation in an eccentric position. The rotary plug is equipped with a control rod drive mechanism, a fuel exchanger, etc., and the fixed plug is equipped with an in-core relay device, a rotary plug drive device, etc. By rotating the rotating plug and the holddown arm of the refueling machine, the refueling machine can be moved to any position above the core, and at this time, the upper core mechanism is moved to a side position that does not hinder refueling. Become. In the double rotation plug system, both the large circle and the small eccentric circle shield plug can rotate, and the same function as described above can be achieved. On the other hand, in the latter hot cell system, the upper part of the reactor is covered as a hot cell, the lid of the reactor vessel can be opened and closed, and the sodium liquid level is lowered to expose the top of the fuel assembly, It is possible to perform visual operation by using such as.

<Problems to be Solved by the Invention> Since the rotating plug for installing the above-mentioned refueling machine and the like had to serve also as a lid of the reactor vessel and shield heat and radiation, its weight is 1 million KWe class. It becomes a heavy object of about 3,000 to 5,000 tons, and it is difficult to manufacture or transport, and the construction cost is high due to the seals and bearings of the rotating part, and maintenance is also difficult. There were many. On the other hand, the hot cell method does not have the problem found in the case of the rotating plug, but it requires a concrete high-temperature airtight chamber for large shielding, and the hot cell will be filled with dangerous radioactive cover gas.
In addition, the condensation and deposition of sodium vapor also requires attention, which is another problem.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a device for performing fuel exchange without opening the lid, without using the rotary plug structure for the lid of the reactor vessel and merely as a fixed lid. Is the purpose.

<Means for Solving Problems> The present invention is such that two pulleys are slidably engaged with an endless rail provided on an upper inner peripheral surface of a reactor vessel, and each pulley is moved on the endless rail. Operable from outside the furnace, these 2
A holddown tube having a gripper with a weight inside is suspended between the pulleys, and the movement of the holddown tube between the two pulleys can be operated from the outside of the furnace as in the case of the pulleys. , Lifting the gripper with weight,
Further, by enabling the operation outside the reactor, the upper core mechanism is lifted into the upper cask, and then the two pulley positions and the holddown tube position between them are appropriately moved to move the gripper position to the reactor. It can be set at any position above the temporary fuel storage pot in the container or above the core,
Therefore, in addition to enabling refueling, it is possible to bring the two pulleys close to each other and hold the holddown tube in a side position where it will not interfere even if the core upper part mechanism returns to a predetermined position. It is the one.

<Example> The following will describe the present invention with reference to an example shown in the drawings.

In FIG. 1, 1 is a reactor vessel, 2 is an endless rail provided on the upper inner peripheral surface of the reactor vessel 1, 3 and 3 are two pulleys slidably engaged with the endless rail 2, and 4 is 2 A holddown tube 5 suspended and held between the individual pulleys 3 and 3 is a gripper with a weight provided inside the holddown tube 4. Explaining from the moving device of each pulley 3 and 3 which encloses the endless rail 2 and eliminates the risk of falling over, the chains 11 and 11 are fastened to both ends of each pulley 3 and 3, respectively. (See Figure 2-C), their chains 11,11
Passes through an annular passage between the endless rail 2 and the endless guide 12 formed concentrically with the endless rail 2 (see FIG. 2-A), and the left and right portions of the great circle of the endless rail 2 are roughly divided into two parts. Using 2 of each of the 3 guide pulleys 13
Two chains 11,11 on the right side, two chains 11,11 on the left side
Launch 11 respectively. On the other hand, the fixed lid 7 for sealing the top of the reactor vessel 1 is provided with through holes 14 and 14 at the portion corresponding to the rising portion, and the outside of the through holes 14 and 14 is provided with a hermetic cover 8 for keeping airtightness. Chain winder covered with 8
6 and 6 are installed. The two chains 11, 11 that stand up to the left and right as described above are passed through the through holes 14, 14 of the fixed lid 7 and are connected to the chain winding devices 6, 6 respectively (see FIG. 1). In this way, the pulley 3 can be slid clockwise or counterclockwise by rotating the proper chain winding device 6, 6 in the forward or reverse direction, and can be moved to a desired set position.

Next, a device for moving the holddown tube 4 will be described. Two chains 15 and 15 are fixed to the upper end of the hold-down tube 4 (see Fig. 2-B). These chains 15 and 15 are used for holding suspensions attached to the pulleys 3 and 3, respectively. Endless guide 12 through the guide pulleys 16, 16 for direction change
Through the annular passage between the inner peripheral surface of the reactor vessel 1 and
(See Fig. A), start up using the remaining guide pulleys 13, 13 among the above-mentioned guide pulleys 13, 13 arranged to the left and right, pass through the through holes 14, 14 of the fixed lid 7, and then seal. It is connected to the chain winding device 6a, 6a in the covers 8, 8 (first
See figure). In this way, the hold-down tube 4 suspended and held between the two pulleys 3 and 3 can be moved to a desired set position by rotating the chain winding devices 6a and 6a in the forward or reverse direction.

The device for raising and lowering the weighted gripper 5 in the holddown tube 4 is as follows. Two chains 17,17 (No. 2-B) fixed to the top of the gripper 5 with weight.
(See the figure) is started by guide rollers 18, 18 provided near the inner peripheral surface of the reactor vessel 1, and a through hole 19 is formed in the fixed lid 7.
Through the through hole 19 and is connected to the chain winding device 6b covered with the sealing cover 8 provided outside the through hole 19 (see FIG. 1).

A cask 9 is formed on the fixed lid 7, and a core upper part mechanism 10 including a control rod drive mechanism can be lifted in the cask 9 (see FIG. 1). This is because when the upper core mechanism 10 is in the normal position it interferes with the fuel exchange, so lift it up to a place where it does not interfere, and after the refueling work is completed, return the upper core mechanism 10 to the regular position again. .

In FIG. 3-A, by bringing the pulley 3 shown by the solid line and the pulley 3 shown by the dotted line close to each other, the position of the holddown tube 4 suspended and held between the pulleys 3 and 3 is changed to the endless rail 2.
It shows the state of being close to. It will be understood that if the core upper part mechanism 10 occupies the normal position by standing by in such a state, no trouble will occur.
At the time of refueling, first the core upper mechanism 10
Lifting inside is as described above.
The operation of the two pulleys 3, 3, the holddown tube 4, and the weighted gripper 5 at the time of refueling is considered to be clear in the above description, but for the sake of caution, it will be briefly described below. Holddown tube 4 has two pulleys 3,
To move the holddown tube 4 located at the center O in FIG. 3-A to the point A while maintaining the relationship at the midpoint of 3, calculate the distance a to the point A and set the radius to r. Then, the chain winding devices 6 and 6 are operated to move the one pulley 3 so that the distance between the two pulleys 3 and 3 becomes 2√r ² −a ^2, and the pulley 3 and the hold down tube are moved. The hold-down tube 4 is moved by operating the chain winding devices 6a and 6a so that the distance between the four becomes √r ² −a ² . Further, in order to move one pulley 3 to the point B in FIG. 3-B with one pulley 3 fixed, the moving angle θ and the distance from the fixed pulley 3 to the point B are calculated, and according to the above, Then, the other pulley 3 may be moved by the angle θ and the hold down tube 4 may be moved by a predetermined length. The weighted gripper 5 occupying the upper position of the core component in this way can be lowered and raised by the operation of the chain winding device 6b, and can grasp and transport the fuel assembly or the like.

<Effects of the Invention> According to the present invention, the weight of the fixed lid 7 can be remarkably reduced as compared with a conventional rotary plug that is heavy, and it is not necessary to rotate it like a rotary plug. It is extremely effective in simplifying and downsizing the reactor structure. Heat shield,
Although radiation shielding is performed outside the reactor vessel 1, it is not necessary to remove the reactor lid at the time of refueling as in the hot cell system, and thus the shielding cell can be small. Moreover, since the holddown tube 4 having the gripper 5 with a weight is suspended and held between the two pulleys 3 and 3 on the endless rail 2 provided along the inner peripheral surface of the reactor vessel 1, these two pulleys 3 , 3 by bringing the reactor vessel 1 closer
A position close to the inner surface can be set as the standby position of the hold-down tube 4, and even if the core upper part mechanism 10 occupies the regular position, it does not disturb anything. At the time of refueling, the upper core mechanism 10 is lifted into the cask 9 to form a space required for refueling, and then the chain winding devices 6, 6a, 6b are appropriately operated to attach the weight. It is extremely excellent in that the gripper 5 can be moved to any position in the furnace and the fuel can be exchanged.

[Brief description of drawings]

FIG. 1 is an explanatory view for understanding the principle of a fuel exchange device for a reactor according to the present invention, FIG. 2-A is a perspective view of an endless rail portion, and FIG. 2-B is a holddown tube and its inside. Sectional view showing a relation between certain weighted grippers, 2-C
The figure is a perspective view of the pulley portion, and FIGS. 3-A and 3-B are plan views for explaining the movement of the two pulleys and the gripper with a weight. 1 ... Reactor vessel, 2 ... Endless rail, 3 ... Pulley, 4 ... Hold down tube, 5 ... Gripper with weight, 6, 6a, 6b ...
Chain winding device, 7 ... Fixed lid, 8 ... Sealing cover, 9 ...
Cask, 10 ... Upper core mechanism.

Claims (1)

[Claims] 1. Two pulleys (3) and (3) are slidably engaged with an endless rail (2) provided on an inner peripheral surface of an upper portion of a reactor vessel (1), and the two pulleys (3) are attached. ) (3) for suspending and holding a holddown tube (4) having a weighted gripper (5) inside, and for moving each pulley (3) (3) on an endless rail (2), two pieces Each chain winding device (6) for moving the holddown tube (4) between the pulleys (3) (3) and for lifting the weighted gripper (5)
(6a) and (6b) are mounted in a closed cover (8) attached to a fixed lid (7) that seals the top of the reactor vessel (1), and a cask (9) is formed on the fixed lid (7). A reactor fuel exchange device, characterized in that the upper core mechanism (10) can be lifted into the cask (9).