JPH0134160Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fuel inlet/output device provided in an ex-core fuel storage tank of a fast breeder power plant.

[Technical background of the invention and its problems]

The fuel burned in the reactor is taken out from the reactor vessel and stored in an extra-core fuel storage tank via a fuel intake/exit chute or the like. During storage, liquid metal is used as a coolant to remove the decay heat of spent fuel (hereinafter simply referred to as fuel). The fuel, which has been kept cool for a certain period of time, is pulled out from the storage rack by a fuel handling machine and moved directly below the fuel inlet/outlet guide cylinder, and then taken out from the out-of-core fuel storage tank by a cask car and transported to the fuel cleaning tank.

By the way, the fuel taken out from the external fuel storage tank still has decay heat, and when stored in the cask car to prevent the fuel from melting due to decay heat, it is cooled by the gas circulation system and transferred to the fuel cleaning tank. etc., to a designated location. During this cooling, the coolant adhering to the fuel is blown out and drips into the drip pan provided in the door valve on the cask car side. This dripping amount is fuel 1
Approximately 100g per body, drip bread is 10-20
When the fuel in the tank is handled, it becomes almost full of dripping coolant, so it is replaced with a drip pan prepared for replacement. The removed drip pan is placed in a storage container with a radiation shielding function and transported to drip pan cleaning equipment, where the dripping coolant is cleaned. The cleaning liquid used for this cleaning is stored in a tank as waste liquid. In one refueling operation, several 100 units are refueled, so
Replacing drip pans and cleaning them requires a great deal of effort, and the storage capacity of the waste liquid has become enormous. Therefore, there is a need for a fuel inlet/output device that can reduce the frequency of maintenance of the drip pan of a tanker, requires less cleaning of activated coolant and treatment of waste liquid, and can shorten the fuel handling schedule.

[Purpose of invention]

This invention was developed in response to the above-mentioned needs.The purpose of this invention is to blow the coolant adhering to the fuel back into the fuel storage tank outside the reactor, thereby significantly reducing the amount of coolant that drips after being stored in the cask car. To provide a fuel inlet/output device equipped with a fuel inlet/outlet guide cylinder which is designed to reduce drip pan replacement work, a series of work associated with this replacement, and waste liquid storage equipment.

[Summary of the idea]

In order to achieve the above object, the present invention includes a fuel storage tank containing a coolant such as liquid metal, a shielding plug provided at the upper end of the storage tank, a through hole provided in the shielding plug, and a fuel inlet/outlet guide tube that passes through the through hole and has an open end immersed in the coolant;
a gripper that grips fuel and moves up and down within the guide cylinder; a gas circulation system that uses the inside of the guide cylinder as a gas flow path; and a gas recirculation system that forms a side path to the guide cylinder and passes through the through hole. The present invention relates to a fuel inlet/output device comprising a gas circulation system and vapor traps disposed above and below the shielding plug in the gas circulation system, and at least a buffer type vapor trap is used as the vapor trap.

[Example of idea]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a longitudinal sectional view of an ex-core fuel storage device equipped with a fuel inlet/output device according to the present invention.

That is, the fuel storage container body 1 is placed on a base 2 and surrounded by a concrete structure, and the spent fuel 4 is contained within the fuel storage container body 1.
Storage rack 3 for storing (hereinafter simply referred to as fuel)
A liquid metal is stored as a coolant 5 for removing the decay heat of the fuel 4 being stored. Further, a shielding plug 6 is provided at the upper part of the storage container main body 1, and a fuel inlet/output chute 7, a fuel handling machine 8, a fuel inlet/outlet guide tube 12, etc. pass through the shielding plug 6 and are attached thereto. As shown in detail in FIG.
2 and a gas recirculation system 15 are penetrated therethrough, and a shield 27 is provided around the guide tube 12 and gas recirculation system 15. Guide tube 1
A gripper 21 controlled by a wire rope 20 is installed in the gas recirculation system 15, and a buffer type vapor trap 23 is installed below the shielding plug 6.
A vapor trap 25 is placed on the top. In addition, 22 is a sealing plate, 26 is a balance hole, 2
9 is a flange.

On the other hand, the fuel inlet/outlet guide tube 12 and the cask car 9 are connected via door valves 10 and 11, and the gas recirculation system 15 of the fuel inlet/outlet guide tube 12 is connected to the gas circulation system 14 of the cask car 9 via the quick connector 19. It is configured as follows. In addition,
16, 17, and 18 are valves.

Incidentally, in a nuclear reactor (not shown), burnt fuel rods, that is, spent fuel, are taken out from the reactor and stored in a storage rack 3 disposed in a fuel storage container main body 1 outside the reactor via a fuel inlet/output chute 7. . The decay heat of the stored fuel 4 is cooled and removed by the coolant 5 housed within the container body 1. In this way, the fuel 4 that has been cooled and held for a certain period of time is pulled out from the storage rack 3 by the fuel handling machine 8 and moved directly below the fuel inlet/outlet guide cylinder 12. The fuel 4 placed directly below the fuel inlet/outlet guide cylinder 12 is gripped by a gripper 21 extending downward from the cask car 9 and pulled upward by a wire rope 20. At a position where the leading end of the fuel 4 that is being pulled up passes the lower end of the guide tube 12, that is, at a position as shown in FIG. 2, the fuel 4 is temporarily stopped and the gas circulation system 14 of the cask car 9 is activated. Since sealing plates 22 are provided between the guide tube 12 and the gripper 21 at two places, upper and lower, the gas flows inside the guide tube 12 and the gripper 2
1 and flows inside and outside the fuel 4 (mostly flows inside), and the coolant adhering to the inside and outside of the fuel 4 is forced to drip downward. Among them, the dripped coolant, which is in a microscopic state, rides on the gas and flows into the gas recirculation system 15, but most of it collides with the buffle plate 24 of the buffle type vapor trap 23 and condenses into droplets and flows downward. . However, the fine refrigerant and vapor that have further risen are captured by the vapor trap 25. The lower end of the guide tube 12 is submerged below the coolant liquid surface, and the guide tube 12 is
Gas will not blow out from the bottom. Further, a small pressure balance hole 26 is provided above the liquid level of the guide tube 12 in order to balance the pressure with the cover gas pressure in the extra-core fuel storage tank. Only a small amount of gas is blown out from the balance hole 26 during gas circulation, and even if the dripping coolant blown out from the balance hole 26 is scattered, the amount that sticks to the shielding plug 6 is almost negligible. After several minutes, the gas recirculation system 15 is stopped, and the fuel 4 is withdrawn again and stored in the cask car 9. Meanwhile, valve 16 is opened, valve 17 is opened,
18 is closed, the gas circulation system 14 is started, and the fuel 4 is
Start cooling. Due to this cooling, the amount of coolant that drips into the drip pan 30 provided in the door valve 10 as shown in FIG. 3 is about 10 g at most, which is a very small amount.

By the way, as shown in FIG. 3, the door valve 10 is provided with an upper flange part 41 and a lower flange part 42 having openings at the upper and lower parts of the shielding side wall 40, respectively, and a lead valve body 33 is arranged inside the upper flange part 41 and the lower flange part 42, respectively. has been done. A drip pan 30 is disposed inside the valve body 33, and a seal plate 34 is disposed between the valve body 33 and a valve seat at the opening of the lower flange 42 via an O-ring 44. This seal plate 3
4 and the valve body 33 are connected by a link 37 between link supports 35 and 36 provided respectively, and the seal plate 34 is connected via a spring 38.
and the valve body 33 are configured to be elastically integrated. Fuel 4 pulled out from storage rack 3
is carried into the cylinder 32 of the drip pan 30, which is slightly raised by the drive shaft 39, held by the handling head 31, and then stored in the cask car 9 as described above. At this time,
Since a stopper 43 is formed in a portion of the shielding side wall 40 corresponding to the seal plate 34, the seal plate that follows the movement of the drive shaft 39 can be safely stopped at a predetermined position.

[Effect of idea]

According to the present invention, since the amount of activated coolant that drips during the withdrawal of fuel stored in the container body of the outside-core storage tank is greatly reduced, the amount of dripped coolant that accumulates in the drip pan is also reduced. Therefore, the amount of fuel processing work such as cleaning the coolant in the drip pan is reduced, and the waste liquid storage facility generated by this cleaning can also be significantly downsized.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of FIG. 1, and FIG. 3 is a sectional view of the door valve of FIG. 1. 1...Storage container body, 3...Storage rack, 4...
...fuel, 5...coolant, 6...shielding plug, 7...
...Fuel inlet/output chute, 8...Fuel handling machine, 9...
Cask car, 10, 11...Door valve, 12
...Fuel inlet/outlet guide tube, 14...Gas circulation system, 15
. . . Gas recirculation system, 23. . . Full type vapor truck, 25. . . Vapor truck, 30. . . Drip pan.

Claims (1)

[Scope of claim for utility model registration] (1) A fuel storage tank containing a coolant such as liquid metal, a shielding plug disposed at the upper end of the storage tank, a through hole provided in the shielding plug, and A fuel inlet/outlet guide tube that penetrates the through hole and has an open end immersed in the coolant, a gripper that moves up and down while gripping fuel within the guide tube, and a gas circulation system that uses the inside of the guide tube as a gas flow path. , a gas recirculation system forming a side passage with respect to the guide tube and penetrating the through hole, and a vapor trap disposed in the gas recirculation system at a lower portion and an upper portion of the shielding plug, respectively. A fuel inlet/output device characterized by: (2) The vapor trap is at least a buffer type vapor trap, which is the first claim for utility model registration.
Fuel inlet/output device as described in section.