JPH0321517Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is based on a hole penetrating a lid provided for transferring fuel from a fuel storage tank that stores new fuel and spent fuel for a nuclear reactor. The present invention relates to a guide tube plug for a fuel storage tank that closes a passage for lifting and lowering fuel in the guide tube, which connects to a delivery port for transferring fuel.

[Prior art and its problems]

In a nuclear reactor that uses liquid as a coolant, such as a fast breeder reactor that uses liquid sodium as a coolant, fuel is stored outside the reactor vessel to temporarily store new fuel installed in the reactor and spent fuel taken out of the reactor. It is known to provide storage tanks. The fuel is transferred into and out of the fuel storage tank using a gripper operated from a fuel intake/discharge machine that connects a hole that passes through the lid of the fuel storage tank and the inside of a guide tube that communicates this hole with a delivery port for transferring fuel. This is done by gripping the fuel and lifting it up and down. When not transferring, insert plugs into the hole and the guide tube, respectively,
Radiation shielding and cover gas sealing are performed. The prior art will be described below with reference to the drawings.

FIG. 3 is a sectional view of a main structural part of a fuel storage tank to which a conventional guide tube plug 21 is connected. The guide cylinder plug 21 includes a sealing plug 9 as a first plug, a sealing plug 10 as a second plug,
It consists of a sealing material 11. In FIG. 3, a container 1 is mounted on a concrete floor (not shown) by a flange 1a, and the container 1 is filled with liquid sodium 2, as in a fast breeder reactor, and a storage rack 3 is provided below the liquid level 2a. New fuel and spent fuel are placed and stored in this storage rack 3. The opening of the container 1 is closed by a lid 4 containing a radiation-resistant material 4a, covering the liquid surface 2a with a cover gas 8. A hole 5 penetrating vertically is provided in the lid 4, and the hole 5 is located at a delivery port for transferring fuel. A guide tube 6 is connected between the door valve 7 and the guide tube 6 . New fuel and spent fuel are gripped by grippers of a fuel inlet/output machine (not shown) and are moved up and down through these holes 5, the inside of the guide tube 6, and the door valve 7, and are moved into and out of the fuel storage tank.
The fuel exiting the door valve 7 is transferred to a downstream fuel handling system by a fuel inlet/outlet machine. If the above-mentioned transfer is not performed, a sealing plug 9 as a first plug is installed in the hole 5 as a guide cylinder plug, and a sealing plug as a second plug is installed in the upper part of the guide cylinder 6. 10 is placed, and a sealing material 1 is placed between the sealing plug 10 and the inner wall of the guide tube 6.
1 is inserted to seal the cover gas.

By the way, when transferring fuel, the shielding plug 9 and the sealing plug 10 are gripped by a gripper (not shown) and removed from the hole 5 and the guide tube 6, and the fuel is transferred to the hole 5 by the fuel inlet/output machine as described above. ,
This is done by moving up and down through the guide tube 6. At this time, when the spent fuel is being transferred, if the guide tube or passage stops for some reason during the transfer, argon gas is used in the guide tube 6 to prevent damage caused by the decay heat of the spent fuel. supply cooling gas. In this case, the cooling gas is delivered from the fuel inlet/output machine and into the fuel through the gripper that grips the fuel. FIG. 4 is a diagram showing the flow of cooling gas to feed the fuel located in the guide tube 6. In the figure, a fuel inlet/output device 12 is arranged on the floor door valve 7, and a gripper 13 is suspended by a tape 14. It's lowered. Gritsupa 13 is spent fuel 1
5 and move up and down inside the guide tube 6. The cooling gas is sent from the fuel inlet/outlet device 12 as shown by arrow A, flows through the internal passage of the gripper 13, and flows inside the spent fuel 15 to cool down the decay heat.

In the above case, since a large amount of cooling gas needs to flow into the spent fuel 15, the gap between the inner wall of the guide cylinder 6 and the outer wall of the gripper is made as small as possible so that the cooling gas does not flow through this gap and contribute to cooling the fuel. In addition to reducing cooling gas, gripper 13
The lifting function shall be ensured.
By the way, as the above-mentioned sealing plugs and sealing plugs, those shown in FIGS. 5 and 6 are conventionally known. In FIG. 5, a grip structure (not shown) provided on the sealing plug 10 at the upper part of the guide tube 6 allows the sealing plug 10 to be moved to the stepped portion 6b of the guide tube 6 by operating it with a gripper of a plug handling machine (not shown). A sealing material 11 is interposed between the sealing plug 10 and the guide tube 6. A stepped portion 6a is provided at the lower part of the guide tube 6 with an inner diameter larger than that of the hole 5. The large diameter portion 9a of the shielding plug 9 is placed on the stepped portion 6a, and the small diameter portion 9b is inserted into the hole. 5 to provide radiation protection. In addition, Shiyahei plug 9
Handling is performed by operating a gripper (not shown) on a grip structure (not shown) provided on the shield plug 9.

In the above structure, when the sealing plug 10 and the shielding plug 9 are removed and the fuel is moved up and down into the guide tube 6, the inner diameter of the guide tube is larger than the inner diameter of the hole, so a gap is created to match the inner diameter of the hole. A gripper that handles such fuel has the drawback that the gap between the inner wall of the guide cylinder and the inner wall of the guide cylinder becomes large, and therefore the flow rate of cooling gas that does not contribute to the above-mentioned cooling becomes large, reducing cooling performance.

In addition, in FIG. 5, in order to reduce the gap, a stepped portion 6a is provided above the guide tube 6 and a small limit portion 9b is provided.
It is also conceivable to lengthen the plug and insert it into the hole 5, but since the shielding plug becomes long, the plug handling machine for attaching and detaching the plug becomes large and the equipment costs are high.

In the other conventional example shown in Fig. 6, the sealing plug 1
The structure and action of 0 are the same as those in Figure 5, but
It is known that the ball latch mechanism 23 is provided at the bottom of the guide tube 6 in the sealing plug 9, the inner diameter of the guide tube 6 and the inner diameter of the hole 5 are made the same, and the gap between the gripper and the guide tube is reduced. Since the ball is exposed to the liquid sodium vapor in the fuel storage tank at high temperature and for a long period of time, sodium adheres to the ball latch mechanism, which deteriorates the operability of the ball latch mechanism and reduces the reliability of the attachment/detachment operation. If the ball latch mechanism is provided at the upper part of the guide tube in order to avoid the above-mentioned adhesion of liquid sodium, the shielding plug will become long and the same drawbacks as mentioned above will occur.

[Purpose of invention]

In view of the above-mentioned drawbacks, the present invention has been developed to effectively pass the cooling gas that cools down the decay heat of the spent fuel when going up and down through the hole provided in the guide tube or the lid of the fuel storage tank. It is an object of the present invention to provide a guide tube plug that closes the hole and the inside of the guide tube during fuel storage so that the cooling efficiency can be increased.

[Summary of the idea]

According to the present invention, the hole provided in the lid of the fuel storage tank through which fuel enters and exits, and the interior of the guide tube that communicates between this hole and the delivery port for transferring the fuel, and guides the lifting and lowering of the fuel. A multilayer telescopic telescoping tube is inserted into the telescoping tube, and a first plug for closing the hole is attached to the lower end of the innermost tube of the telescoping tube, and the tube or the first plug is inserted from above. A grip structure operated by a gripper is provided, and the upper end flange of the outermost tube can be placed on the stepped portion of the guide tube, and the inner diameter of the guide tube is extended from the connecting surface with the hole to the stepped portion. In between, a sealing material made to be the same as the inner diameter of this hole and interposed between the guide tube and a second plug for sealing placed on the upper part of the guide tube is placed above the telescopic tube. This is achieved by providing

[Example of idea]

Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a sectional view showing a state in which a guide tube plug according to an embodiment of the present invention is attached to a guide tube of a fuel storage tank 20. As shown in FIG. In FIG. 1 and FIG. 2, which will be described later, the same parts as in the conventional example shown in FIGS. 3 to 6 are given the same reference numerals. The guide cylinder plug 22 includes a first plug 9, a second plug 10, and a sealing material 1.
1. It consists of a telescopic tube 16, an actuator 18, and a latch ball 19.
In Fig. 1, the opening of the fuel storage tank is closed and a lid 4 with a built-in radiation shielding material 4a is provided with a hole 5 vertically penetrating through it to allow new fuel and spent fuel to enter and exit the fuel storage tank. It is being And this hole 5
and floor door valve 7 at the upper fuel delivery port.
A guide tube 6 is provided that communicates between the floor door valve 7 and the floor door valve 7, and serves as a guide for raising and lowering the fuel by operating a gripper from a fuel inlet/output machine 12 located above the floor door valve 7. A telescope-shaped telescopic tube 16 consisting of multiple tubes is inserted into the guide tube 6, and the lower end of the innermost tube 161 of the telescopic tube 16 is above the shrinkage plug 9 as a first plug. It is attached to the end surface 9a. The upper end flange portion 16a of the outermost tube 16n of the telescopic tube 16 is placed on the stepped portion 6a of the guide tube 6.

A grip structure 16d is provided at the upper end of the innermost tube 161 of the telescopic tube 16, and is gripped and released by a gripper 17 operated from an upper plug handling machine (not shown).

Note that the inner diameter of the guide tube 6 is equal to the hole 5 provided in the lid 4.
A hole 5 is formed between the surface connected to the stepped portion 6a and the stepped portion 6a.
The inner diameter is the same as that of the

At the upper part of the guide tube 6, a sealing plug 10 as a second plug is placed on the stepped part 6b of the guide tube, and the sealing plug 10 and the guide tube 6
A sealing material 11 interposed between the retractable tube 16 and the retractable tube 16 is provided at a position above the collar portion 16a to prevent leakage of the cover gas in the in-furnace storage tank. Further, on the top of the sealing plug 10, there is an actuator 18 with a grip structure and a latch ball 19.
A ball latch mechanism is formed by providing a latch groove 6c on the inner wall of the guide tube 6. Then, the sealing plug 10 is attached to and detached from the guide tube 6 by a gripper 17 operated by an upper plug handling machine (not shown). Further, the grip structure of the actuator 18 is handled by the gripper 17, and the seal plug 10 can be raised and lowered via the actuator 18.

Next, in the above structure, the sealing plug 9 and the sealing plug 1 are used as guide tube plugs.
0 will be explained below.

As shown in FIG. 2, the innermost tube 161 of the telescopic telescopic tube 16 consisting of multiple tubes.
The above-mentioned grip structure 16d is gripped and retracted by the gripper 17 together with the shield plug 9 attached to the gripper 17. When the inside of the guide tube 6 is suspended in this state, the outermost tube 16 of the telescopic tube 16
The n flange portion 16a is placed on the stepped portion 6a of the guide tube 6. If it is hung as it is, the multi-tube telescopic tubes 16 will expand one after another until the innermost tube 1
61 is pulled out, and the sealing plug 9 is positioned in the hole 5 of the lid 4, completing the installation.

Each tube of the multiple tube has a collar and a stopper provided at both ends of the tube, for example, the middle tube 16m has a stopper 1 provided at the lower end of the outermost tube 16n as shown in FIG.
A collar 16f provided at the upper end of the middle tube 16n is placed on the tube 6g and extends. This action is performed on each stage of tubes until they are fully extended.

Next, the sealing plug 10 is attached in this state. In this case, as shown in FIG. 1, a sealing material 11, such as an O-ring packing, is first attached to the sealing plug 10 in advance. Next, seal plug 1
When the actuator 18 of the ball latch mechanism provided at 0 is grasped and lifted by the gripper 17, the actuator 18 hits the collar 10a at the upper end of the sealing plug, and the sealing plug 10 can be hung. Then, the gripper 17 is lowered, the sealing plug 10 is inserted into the guide tube 6, and the sealing plug 10 is placed on the stepped portion 6b of the guide tube 6. When the gripper 17 is further lowered, the actuator 18 is lowered, and the latch ball 19 is pushed out in the radial direction as shown by the arrow and fits into the latch groove 6c provided on the inner wall of the guide tube 6, thereby fixing the sealing plug. Next, operate the gripper 17 to
from the sealing plug 10. In this case O
The ring packing 11 is interposed between the sealing plug 10 and the guide tube 6 to prevent the cover gas of the fuel storage tank from leaking to the outside. In this case, since the sealing plug 10 forms the pressure boundary of the fuel storage tank, the pressure inside the guide cylinder becomes uniform, so that the telescopic tube does not contract due to the pressure difference.

To remove the shielding plug 9 and the sealing plug 10, follow the above-mentioned procedure in reverse. First, the sealing plug 10 is removed, and then the multi-tube telescope with the shielding plug 9 attached is removed. After the scope-shaped telescopic tube is shortened, it is taken out of the guide tube.

In this embodiment, the grip structure 16d is provided on the innermost tube 161, but the same effect can be obtained even if the grip structure 16d is provided on the upper part of the shielding plug 10. In addition, in this embodiment, in order to prevent the radiation of spent fuel etc. that moves up and down other guide tubes installed in parallel,
The sealing plug 10 is lengthened to form a telescopic tube 16.
However, if such radiation protection is not required, it may be shortened so that it is placed above the telescopic tube.

[Effect of idea]

As is clear from the above description, according to the present invention, a shielding plug that penetrates the lid of a fuel storage tank and shields the hole through which fuel enters and exits is a telescope-shaped telescopic tube consisting of multiple tubes. The plug is attached to the innermost tube of the tube, and the insulation plug is inserted into the hole by the extension of the telescoping tube.
Since the inner diameter of the guide tube can be made the same as the inner diameter of the hole by taking it out of the guide tube by reducing the length, the spent fuel can be removed between the hole and the outer wall of the gripper that raises and lowers the guide tube. Since the gap between the guide tube and the inner wall can be reduced at the same time, the cooling gas sent from the fuel inlet/output machine flows through the gap, reducing the flow rate of cooling gas that does not contribute to cooling, and allowing a large amount of cooling gas to flow through the internal passage of the gripper. This has the effect of effectively cooling the decay heat of the spent fuel. Further, there is no need to increase the length of the shielding plug as in the prior art, which has the effect of reducing equipment costs due to an increase in the size of the plug handling machine.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing a state in which a guide tube plug of a fuel storage tank according to an embodiment of the present invention is attached to a guide tube, FIG. 2 is a partial sectional view showing a structure in which the telescopic tube in FIG. 1 is shortened, Figure 3 is a schematic cross-sectional view showing the state in which the guide cylinder plug of a conventional fuel storage tank is attached to the guide cylinder, Figure 4 is a cross-sectional view showing the flow of cooling gas that cools the spent fuel, and Figure 5 is a cross-sectional view showing the flow of cooling gas that cools the spent fuel. 4
FIG. 6 is a partially enlarged sectional view showing a conventional example different from that in FIG. 4. 1... Container, 2... Liquid coolant, 4... Lid, 5
...hole, 6 ... guide cylinder, 8 ... cover gas, 9 ...
...Plug for shielding as the first plug, 10
...Sealing plug as second plug, 11
... Seal material, 15 ... Spent fuel, 16 ... Telescopic tube, 17 ... Gripper, 18 ... Actuator, 19 ... Ball for latch, 20 ... Fuel storage tank, 21, 22 ... Guide tube plug .

Claims (1)

[Scope of utility model registration request] A container that accommodates new fuel and spent fuel for a nuclear reactor is filled with a liquid coolant, the fuel is stored below the liquid level of the liquid coolant, and the liquid level is covered with a cover gas to open the container. A lid that closes the opening and has a built-in radiation-resistant material, and a lid that passes through the lid in the vertical direction and communicates with a hole in the container through which fuel can be taken in and out and a delivery port that transfers the fuel; A first plug for shielding radiation is provided in the hole of the guide tube in a fuel storage tank consisting of a guide tube for guiding vertical movement. A second plug that closes the opening of the guide tube by a ball latch mechanism is placed on the stepped part at the top of the guide tube, and a sealing material is interposed between the second plug and the guide tube, The guide tube plug is detachable from above using a gripper, and a telescopic telescopic tube consisting of multiple tubes is inserted into the guide tube, and the first plug is attached to the lower end of the innermost tube of the telescopic tube. The tube or the second plug is provided with a grip structure to be gripped and released by the gripper, and the upper end flange of the outermost tube can be placed on the stepped portion of the guide tube, and the tube or the second plug is provided with a grip structure for gripping and releasing by the gripper. The inner diameter of the tube is made the same as the inner diameter of the hole between the connection part with the hole and the stepped part, and the sealing material between the second plug and the guide tube is provided above the telescopic tube. A guide tube plug for a fuel storage tank characterized by: