JP2000028784A - Method for carrying in and out container for accommodating spent fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce risk where a working personnel who carries in and out a canister is exposed to radiation by introducing water into a storage chamber when carrying in and out a container, and by carrying in and out the container while the container is under water. SOLUTION: When a canister 1 where spent fuel is accommodated is carried from a storage chamber 2, a supply pump 11 is driven, and water being stored in a storage tank 13 is supplied into the storage chamber 2. Then, when water being supplied to the storage chamber 2 reaches a water level that exceeds the height of the canister 1, water supply to the storage chamber 2 is stopped, and at the same time a shielding lid 5 is removed from a hole 4 for entering and leaving the canister. The canister 1 being accommodated in the storage chamber 2 is hoisted by a movement crane 6, and the canister 1 is carried from the hole 4 for entering and leaving the canister. Also, the canister 1 where the spent fuel is accommodated is carried in the storage chamber by the same procedures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for loading and unloading a spent fuel container applied to a spent fuel storage facility used in a nuclear power plant.

[0002]

2. Description of the Related Art Spent fuel used in a nuclear power plant is stored in a spent fuel pool in the power plant for a certain period of time and then reprocessed in a reprocessing plant. Due to the lack of processing capacity and the capacity of the spent fuel pool, there is an increasing need to store spent fuel in facilities outside the power plant for a certain period of time.

FIG. 6 shows an example of a storage facility for storing spent fuel used in a nuclear power plant for a certain period of time. In FIG. 6, reference numeral 1 denotes a cylindrical spent fuel storage made of metal such as iron. A container (hereinafter, referred to as a canister) 2 indicates a storage chamber for storing and storing the canister 1 containing the spent fuel.

The storage chamber 2 is formed below the ground surface 3 in order to shield radiation emitted from spent fuel, and the ceiling of the storage chamber 2 has a diameter larger than the outer diameter of the canister 1 by one degree. Canister access holes 4 are formed at a constant pitch. These canister access holes 4 are openably closed by a shielding lid 5 made of concrete. Above the shielding lid 5, a movable crane 6 for hanging the canister 1 on the floor 2a of the storage chamber 2 is provided. Have been.

[0005] The storage chamber 2 is made of concrete to prevent intrusion of rainwater and the like, and an air supply passage 7 is formed inside a concrete wall forming the wall surface of the storage chamber 2. Air (outside air) flows into the air supply passage 7 from an air intake 8 provided on the ground, and the air flowing into the air supply passage 7 traverses the inside of the storage chamber 2 from the left side in the figure. After ventilating to the right, the air flows into an air outlet 9 provided on the lower surface of the ceiling wall of the storage chamber 2, and is discharged from the air outlet 9 to the atmosphere through an exhaust tower 10.

In the storage facility described above, the canister 1 containing the spent fuel is cooled by the air passing through the inside of the storage chamber 2, so that the decay heat generated from the spent fuel is removed through the canister 1. It has the advantage that it can be heated.

[0007]

However, when the canister 1 is carried into the storage chamber 2 or when the canister 1 is carried out from the storage chamber 2, the shielding cover 5 is removed from the canister access hole 4, and the canister access port is removed. 4
When the canister 1 is loaded and unloaded, radiation is emitted from the canister access hole 4 to the ground, which may increase the radiation exposure of workers operating the mobile crane 6. was there. In addition, it was necessary to install a large-scale shielding structure on the ground in order to suppress the exposure of workers operating and operating the mobile crane 6.

The present invention has been made in view of the above problems, and can prevent radiation from being emitted to the ground from an opening formed in a ceiling portion of a storage chamber when a canister is loaded and unloaded, and canister loading and unloading canisters. An object of the present invention is to provide a method of carrying in and out a canister that can reduce the exposure of workers engaged in carrying out work.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a storage chamber made of concrete is provided underground, and the spent fuel storage carried into the storage chamber from above is stored. The present invention is applied to a spent fuel storage facility in which a container is cooled by air passing through the storage chamber to remove decay heat of the spent fuel stored in the container, and the storage is performed when the container is loaded and unloaded. Water is introduced into the chamber, and the container is loaded and unloaded while the container is immersed in the water. The invention according to claim 2 is characterized in that the storage chamber is divided into a plurality of storage blocks, and water is introduced into each block to carry in and out the container. The invention according to claim 3 is characterized in that the spent fuel storage facility has a water storage tank, and water is introduced into the storage chamber from the water storage tank to carry in and out the container.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those shown in FIG. 6 are denoted by the same reference numerals, and detailed description of those parts will be omitted. FIG. 1 is a view for explaining an embodiment of the present invention. In the figure, reference numeral 11 denotes a water supply pump as water supply means. A water storage tank 13 is connected to a suction port of the water supply pump 11 via an on-off valve 12.
The water discharged from 1 is supplied to the storage chamber 2 via the on-off valve 14 and the water supply pipe 15. In the figure, reference numeral 16 denotes a drainage pump for returning the water supplied to the storage chamber 2 to the water storage tank 13 via the water pipe 17.

In such a configuration, when the canister 1 containing the spent fuel is carried out of the storage chamber 2, first, the water supply pump 12 is driven to supply the water stored in the water storage tank 14 to the storage chamber 2. I do. When the water supplied to the storage chamber 2 reaches a water level exceeding the height of the canister 1, the supply of water to the storage chamber 2 is stopped, and the shielding lid 5 is removed from the canister access hole 4. Next, the canister 1 housed in the storage chamber 2 is lifted by the movable crane 6, and the canister 1 is carried out from the opened canister access port 4. When the canister 1 containing the spent fuel is carried into the storage chamber 2, the work of carrying the canister 1 is performed in the same procedure.

As described above, in one embodiment of the present invention, water is supplied to the storage chamber 2 when the canister 1 is loaded and unloaded, and the canister 1 stored in the storage chamber 2 is immersed in the water. The radiation from the spent fuel stored in the storage chamber 2 is shielded by the water supplied to the storage chamber 2 in order to perform the loading / unloading operation. Therefore, it is possible to prevent radiation from being emitted to the ground from the canister access hole 4 formed in the ceiling of the storage chamber 2 when the canister 1 is loaded and unloaded.
It is possible to reduce the exposure of workers engaged in loading and unloading work.

In the embodiment described above, the canister 1
Although the water stored in the water storage tank 14 was supplied to the entire storage chamber when loading and unloading the water, the storage chamber 2 was divided into a plurality of storage blocks 18 as shown in FIG. Water may be supplied to each storage block 18. By doing so, the amount of water supplied to the storage chamber 2 is reduced, so that the size of the water storage tank 14 can be reduced.

In the above-described embodiment, a plurality of canister access holes 4 are provided in the ceiling of the storage chamber 2, and the canister 1 is carried into the storage chamber 2 from these canister access ports 4. It is not always necessary to provide the canister entrance / exit hole 4 in the ceiling portion. For example, if the ceiling of the storage chamber 2 is configured by alternately combining reinforced concrete shields 19a as shown in FIG. 3A and reinforced concrete shields 19b as shown in FIG. At the time of loading / unloading 1, the ceiling of the storage chamber 2 can be opened as shown in FIG.

Further, as shown in FIG.
A transport cask temporary storage pit 20 is provided on the floor 2a of the vehicle.
May be carried out.

[0016]

As described above, according to the present invention,
Radiation can be prevented from being emitted to the ground from the opening formed in the ceiling of the storage chamber when the canister is loaded and unloaded, and exposure of workers engaged in loading and unloading the canister can be reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of the present invention, and is a longitudinal sectional view of a spent fuel storage facility.

FIG. 2 is a diagram for explaining another embodiment of the present invention;
It is a top view of a spent fuel storage facility.

FIG. 3 is a diagram illustrating an example of a shield constituting a ceiling portion of a storage chamber.

FIG. 4 is a perspective view of a storage chamber in which a ceiling is formed by the shield shown in FIG. 3;

FIG. 5 is a longitudinal sectional view of a spent fuel storage facility having a transport cask temporary storage pit on the floor of a storage chamber.

FIG. 6 is a longitudinal sectional view of the spent fuel storage facility.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 canister 2 storage chamber 4 canister access hole 5 shielding lid 6 mobile crane 7 air supply passage 8 air intake 9 exhaust port 10 exhaust tower 11 water supply pump 13 water storage tank 16 drainage pump

Claims (3)

[Claims] 1. A storage chamber made of concrete is provided underground, and a spent fuel storage container carried into the storage chamber from above is cooled by air flowing through the storage chamber and stored in the storage chamber. It is applied to a spent fuel storage facility that removes the decay heat of spent fuel, wherein water is introduced into the storage chamber when the container is carried in and out, and the container is immersed in water. A loading / unloading method for a spent fuel storage container, wherein the loading / unloading operation is performed. 2. The spent fuel container according to claim 1, wherein the storage chamber is divided into a plurality of storage blocks, and water is introduced into each block to carry in and out the container. Loading and unloading method. 3. The use according to claim 1, wherein the spent fuel storage facility has a water storage tank, and water is introduced into the storage chamber from the water storage tank to carry in and out the container. For loading and unloading spent fuel containers.