JPS6032636Y2 - Spent fuel canister - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a sealed can for containing spent fuel bodies of a nuclear reactor.

As a result of being retained in the reactor for a long period of time, the spent fuel bodies of a nuclear reactor are irradiated with radiation and have a high level of radioactivity and a high level of decay heat.

For this reason, the spent fuel assemblies pulled out from inside the reactor cannot be immediately transported to the fuel reprocessing facility. It is common practice to cool and store products by immersing them in water for a predetermined period of time in a cooling water pool.

In this case, the spent fuel body is housed in a sealed can together with a cooling medium with excellent heat conductivity such as helium gas, and the fuel body is stored cooled by immersing the sealed can in a cooling water pool.

After a predetermined cooling storage period, the sealed can is lifted from the cooling water pool, placed in a transfer cask, and transported to a fuel reprocessing facility.

This type of sealed can has already been used in liquid metal cooled fast reactors, and its structure consists of a bottomed can body and a can lid.The can lid also has a top part that protrudes above the lid plate. A cylindrical handling head is provided with a handling part that engages with the gripper claws of a handling machine such as a lane that runs along the can body, and is used to lift and lower sealed cans along the fuel body transport line along with the can body. It is configured so that it can be done.

Since such conventional sealed cans have a recess formed in the cylindrical handling head of the can lid, water remains in the handling head when the can is lifted upward from the cooling water pool.

Moreover, since the sealed can containing the spent fuel is handled in a vertical position and stored in the cask, if the residual water is left unattended, this water will undesirably be carried into the cask.

Conventionally, as a preventive measure, a method has been adopted in which drying equipment is placed midway along the fuel assembly transport route to evaporate and dry the water remaining in the handling head. Not only is it necessary to take precautionary measures and large-scale equipment is required, but the time required to carry out the fuel assembly becomes longer, which affects the schedule of reactor operation.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a practical sealed can in which water from a cooling water pool does not remain in the handling head.

Hereinafter, the structure of the sealed can according to the present invention will be described in detail based on illustrated embodiments.

In the figure, 1 is a can body with a bottomed cylindrical structure, and 2 is a can body 1.
The can lid is airtightly covered on the top surface of the can body 4, and a spent fuel body 4 is housed in the can body 4 along with a cooling medium 3 such as helium gas.

In addition, the can lid 2 is screwed or bolted to the can body as shown in the example shown in the figure, and the can body and the can lid are further welded and sealed as shown by the symbol W in the outer circumferential area. to maintain complete airtightness.

On the other hand, the upper part of the can lid 2 is provided with a cylindrical handling head 22 that protrudes upward from the lid plate 21, and a handling portion 23 serving as a hook groove is provided on the inner peripheral side of the top.

As is well known, the gripper claw 6 suspended from a handling machine such as a running lane engages with the handling part 23, and the entire sealed can is raised and lowered in the direction of arrow A by operating the handling machine. It is.

Note that the reference numeral 7 indicates water in the cooling water pool, and the figure shows a state in which the sealed can is being pulled up from the cooling water pool.

By the way, according to the present invention, the handling head 22 is provided with a drain hole 24 for draining water that opens near the bottom surface and communicates the inside and outside of the cylindrical handling head.

The drain holes 24 are provided at multiple locations around the handling head.

According to the sealed can having the above configuration, the spent fuel body 4 is hermetically housed in the can together with the cooling medium 3, and after being cooled and stored in the cold water pool for a predetermined period of time, when the spent fuel body 4 is pulled out from the pool as shown in the figure. The handling head 2 forming a recess is
The water 7' in the cooling water pool accumulated inside the cooling water pool 2 is immediately drained into the pool as shown by arrow B through the drain hole 24 described above, and no residual water is generated.

Therefore, even when the sealed can containing the fuel body 4 is stored in the transfer cask for transport to the fuel reprocessing facility, there is no risk of bringing water into the cask, and furthermore, since the water will evaporate during the transport route within the facility. This also eliminates the need for additional equipment.

This is advantageous for the operating schedule of the nuclear reactor, since the work time required for removal can be shortened compared to the conventional method.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view of an embodiment of the present invention. 1: Can body, 2: Can lid, 22: Handling head, 2
3: Handling part, 24: Drain hole, 3: Cooling medium,
4: Spent fuel body, 6: Gripper claw, 7: Ice in the cooling pool, 7': Water accumulated in the handling head, B: Drain water discharge direction.

Claims (1)

[Scope of utility model registration request] It consists of a combination of a can body and a can lid equipped with a cylindrical handling head with a handling part on the top that engages with the gripper claws of a handling machine. A sealed can for cooling and storing spent fuel by immersing it in water in a cooling water pool, with a drain hole that opens near the bottom of the handling head and connects the inside and outside of the cylindrical handling head. A sealed can for spent fuel from a nuclear reactor, characterized by: