JP2933951B2 - Handling of used core components of fast reactors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a spent fuel for a fast breeder reactor, an agent control rod,
Sodium (coolant) adhering when used core components such as used shields are taken out of the reactor, transported and stored
The present invention relates to a handling method for transporting and storing used core components in an ingot state by washing and removing spent core components.

[Conventional technology]

When a spent core component of the fast breeder reactor, for example, spent fuel is carried out of the reactor, it is necessary to wash and remove the attached sodium (reactor coolant).

Normally, in practical use plants, it is necessary to remove spent fuel with high heat from the core in a pot filled with sodium, but it is necessary to submerge this pot filled with sodium into the pool water The thing is Na-
It is impossible because of the need to prevent water reaction, and it is necessary to clean the spent fuel to remove the attached sodium.

For this reason, prior to storing the spent fuel extracted from the core in the water pool, the pot containing the spent fuel extracted from the core is placed in a separation tank filled with sodium. Transfer, then supply molten metal having a higher specific gravity than sodium and a melting point lower than the sodium temperature in the separation tank in the separation tank, and a low reactivity to sodium and water in the water pool to remove sodium. To wash the spent fuel, and then transfer it to the water pool with the molten metal in the pot, and remove the naked spent fuel from the pot in the water pool and store it in the water pool. There is a fast reactor spent fuel cleaning method. As a prior art document, there is JP-A-63-21597.

[Problems to be solved by the invention]

By the way, in the above-mentioned fast reactor spent fuel cleaning method, since spent fuel is stored naked in a water pool, equipment for handling damaged fuel requires separate canning and the like. In addition, since the low-melting-point metal is mixed into the water in the water pool, it is necessary to remove the low-melting metal in the water pool purification system, and equipment for this is also required.
Furthermore, since a water pool is used as a storage facility, a relatively large amount of radioactive waste is generated from the pool water purification system.

Therefore, the present invention does not require equipment for handling damaged fuel,
Also, when using a water pool, use fast reactors such as spent fuel and other used control rods, used shields, etc. so that no metal is mixed into the water in the water pool and no radioactive waste is generated. It is an object of the present invention to provide a handling method for cleaning, transporting and storing used core components.

[Means for solving the problem]

In order to solve the above-mentioned problems, the method for handling a spent core component of a fast reactor according to the present invention includes removing the spent core component from an electronic furnace in a state where the spent core component is stored in a fuel transfer pot containing sodium, and placing the spent core component in a separation tank. In the separation tank, a metal having a high melting point and a higher specific gravity than sodium, and not dissolving at high temperature with sodium, is supplied in a molten state with a metal having excellent heat transfer characteristics, and the sodium is floated to the top to overflow and be removed. The refractory metal in the fuel transfer pot is solidified, and then the spent core components are transported and stored in an ingot state.

[Action]

As described above, in the method for handling a spent core component of a fast reactor according to the present invention, after placing a fuel transfer pot containing sodium containing a spent core component in a separation tank, the specific gravity is larger than that of sodium and the sodium is melted at a high temperature. Without introducing high melting point molten metal with excellent heat transfer characteristics into the fuel transfer pot, sodium is floated and removed above, and the molten metal is solidified to solidify the spent core components in the fuel transfer pot. Stored in a metal-enclosed state.For example, if the spent core component is damaged fuel, the damaged hole is sealed with molten metal, so it can be handled in the same way as a healthy fuel, and no special equipment is required. It is. Also, if the outer surface of the fuel transfer pot is stored while being cooled with air, almost no radioactive waste is generated. Furthermore, by using a metal that does not react with water, even when a water pool is used for storage, no metal is mixed into the water of the water pool, so there is no need for equipment to remove metals in the water pool purification system. In addition, since the sodium remaining on the surface of the spent fuel does not come into contact with water and does not react, the radioactive corrosion products do not diffuse, and the exposure during maintenance and repair is small.

It is also possible to handle damaged fuel by returning it to the core after forming it into an ingot and storing it in the damaged fuel storage area of the core.

〔Example〕

One embodiment of the method for handling spent core components of a fast reactor according to the present invention will be described with reference to FIG. 1. Spent fuel 2 generated in a reactor core 1 is transported to a refueling position 5 by a fuel exchanger 3 and a rotary plug 4. Into the fuel transfer pot 6 prepared in advance. The fuel transfer pot 6 is pulled up into the Ar gas cell 9 through the ramp 8 by the fuel access device 7,
Is temporarily stored in the relay layer outside the furnace 10 by the swing operation and the hanging-down operation.

After that, the fuel transfer pot 6 is lifted and transferred from the inside of the relay layer 10 outside the furnace by the fuel transfer device 11, and is suspended in the separation tank 12. Next, in the separation tank 12, as a metal having a high melting point, a higher specific gravity than sodium, hardly reacting with sodium and water, and having excellent heat transfer characteristics, for example, Al (melting point 660 ° C.,
Specific gravity of about 3) or Al-Si 13% alloy (referred to as silumin).
An aluminum alloy having a melting point of 570 ° C. and a specific gravity of about 3) or cadmium (melting point of 321 ° C. and a specific gravity of about 8.6) is supplied in a molten state, and the sodium that has been introduced into the fuel transfer pot 6 is removed from the upper portion. Overflow is removed from the overflow hole. Next, the molten metal in the fuel transfer pot 6 is solidified by natural cooling, and the spent fuel 2 inside is sealed. The spent fuel 2 in the ingot state is lifted and transferred from the separation tank 12 by the fuel transfer device 11 for each fuel transfer pot 6, and is used for fuel transfer in the basement 14 connected to the adjacent air cell 13 from the Ar gas cell 9. The fuel is transported to the air cell 13 side by the traveling of the fuel transfer cart 15, and the fuel transfer pot 6 is pulled up from the fuel transfer cart 15 into the air cell 13 by the fuel transfer machine 16 in the air cell 13. It is transported, suspended and stored in a storage 17 underground.

As described above, in the method for handling a spent core component of a fast reactor according to the present invention, the sodium-containing fuel transfer pot 6 containing the spent fuel 2 is placed in the separation tank 12, and the specific gravity of the fuel transfer pot 6 is larger than that of sodium. A metal having low reactivity with sodium and a high melting point is introduced in a molten state, sodium is removed by overflowing, and the molten metal is solidified and stored in a state in which spent fuel 2 is sealed in an ingot. When the fuel 2 is damaged, the damaged hole is sealed by the molten metal and solidified. Therefore, the same handling as the healthy spent fuel 2 can be performed, and no special equipment is required. Further, when the fuel is stored in the underground storage 17, air is blown into the storage 17 by the blower 18 as shown in FIG. 1 and the outer surface of the fuel transfer pot 6 is stored while being cooled by air. Almost no waste is generated. Further, when a metal having no reactivity with water is used instead of being stored in the underground storage 17, when the metal is stored in the storage rack 20 in the water pool 19 shown in FIG. Since no metal is mixed into the water, no equipment for removing the metal in the water pool purification system is required, and the sodium remaining on the surface of the spent fuel 2 does not come into contact with the water, and the reaction occurs. Absent.

In the above embodiment, the method of handling the spent fuel has been described. However, the handling of the used control rod and the used shield is also performed in the same manner.

〔The invention's effect〕

As can be seen from the above description, according to the method of handling a spent core component of a fast reactor according to the present invention, a facility for handling damaged fuel, which has been conventionally required, becomes unnecessary, and the fuel handling system can be simplified. In addition, since the spent core components are stored in the fuel transfer pot in the state of being sealed in the ingot, storing the fuel transfer pot while cooling it causes almost no generation of radioactive waste. Furthermore, when the above-mentioned fuel transfer pot is stored in the water pool, metal does not mix with the water in the water pool. Therefore, no metal removing equipment is required in the water pool purification system, and the surface of the used core component should be used. Even if sodium remains, since it is contained in the ingot and does not directly react with the water in the water pool, a water pool storage system can be established.

[Brief description of the drawings]

FIG. 1 is a view showing a fuel handling system for carrying out a method for handling a spent fast reactor core component of the present invention, and FIG. 2 is a view showing a partially modified example of FIG. 2 Spent core components (spent fuel) 6 Fuel transfer pot, 12 Separation tank

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Shigeto 2-4-25 Minamisuna, Koto-ku, Tokyo Kawasaki Heavy Industries, Ltd. Tokyo Design Office (58) Field surveyed (Int. Cl. ⁶ , DB name) G21C 19/32 G21C 19/18

Claims (1)

(57) [Claims] 1. A spent core component is taken out of an electronic furnace in a state in which it is stored in a fuel transfer pot containing sodium, and is put into a separation tank. Next, the separation tank has a high melting point, a higher specific gravity than sodium, and The metal which does not melt at high temperature and has excellent heat transfer properties is supplied in a molten state, and the sodium is floated to the top to overflow and remove it.
Next, the high melting point metal in the fuel transfer pot is solidified,
A method for handling spent core components in a fast reactor, comprising transporting and storing the spent core components in an ingot state thereafter.