JPS6314918B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for raising and lowering a spent fuel transport container employed in a spent fuel storage pool or the like.

Spent fuel assemblies from a nuclear reactor are stored in water in a spent fuel storage pool for a certain period of time, cooled at the same time, and then stored in a spent fuel transport container (cask) and transported to a reprocessing plant. or sent to a spent fuel storage facility. When the fuel assembly arrives at the reprocessing plant or storage facility, it is removed from the transport container and stored in water in a storage pool.
The above-mentioned work of storing nuclear fuel in a transport container on the reactor side and work of removing nuclear fuel from the transport container on the side of a reprocessing plant or storage facility are performed in a storage pool or a storage pool because the radioactivity of the nuclear fuel is extremely high. Usually, this is carried out underwater in a fuel storage pool or fuel extraction pool connected by a waterway or the like using water as a shield. In such spent fuel storage and removal operations, the outer surface of the transport container will come into direct contact with the pool water, and there is a high possibility that the transport container will be contaminated by radioactive substances in the pool water. For this reason, it is necessary to remove the contamination on the outer surface of the transport container using high-pressure water, etc. before transporting the transport container outside the facility, but in reality, this cleaning process is difficult and requires a great deal of labor and time. ing. Conventionally, in order to prevent contamination of the outer surface of a transport container, for example, a bag-like cover was placed over the transport container.
Efforts are being made to prevent the outer surface of the transport container from coming into direct contact with pool water. However, in this case, it is necessary to put the cover on the transport container while it is suspended by a crane, which is a dangerous operation. Furthermore, not only is there a risk of contamination due to a defective cover, but the cover itself is also contaminated, which is undesirable in post-processing.

According to the present invention, a plurality of guide grooves are formed on opposing side surfaces of a fuel handling pool, each extending over almost the entire length in the vertical direction, and the buckets guided through the guide grooves through guided members are guided through the fuel handling pool. The bucket is submerged in a pool, and the bucket is first lifted up and floated by a crane, and the guided member is locked in the locking groove continuous to the upper end of each guide groove, and then the spent fuel transport container is placed inside the bucket. The space between the top end of the spent fuel transport container and the top end of the bucket is closed with an annular lid, and the bucket is lowered and submerged into the fuel handling pool together with the spent fuel transport container while being suspended by a crane. According to this method, it is possible to prevent contamination of the outer surface of the spent fuel transport container, and it is possible to prevent the storage and removal of spent fuel. Work can be done safely, reliably and quickly, and a drive device for lifting and lowering the bucket is not required, making the structure extremely simple.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 to 3. Reference numeral 1 denotes a rectangular fuel handling pool with one side open, and a guide groove 2 is formed in a pair of opposing sides over almost the entire length in the vertical direction.
The guide grooves 2 are arranged in pairs, front and rear, at a predetermined interval on each side surface. The upper end of each guide groove 2 is continuous with a locking groove 4 formed in front of the guide groove 2 via a curved guide surface 3. Reference numeral 5 designates a cylindrical bucket with a bottom and only the upper part is open, and on both sides thereof, the bucket is guided by each guide groove 2 and has each locking groove 4.
A plurality of guided members 6 that can be locked are provided. The guided member 6 includes a roller shaft 7 that projects laterally from the bucket 5 and a roller 8 that is attached to the roller shaft 7. A trunnion 9 is provided on the outer periphery of the upper end of the bucket 5, and a cushioning material 10 is installed on the fuel handling pool 1.
It is done through. Reference numeral 11 denotes a seated cylindrical spent fuel transport container, which has fins 12 on its outer periphery. This transport container 11 can be stored in a bucket 5, and its landing is carried out via a cushioning material 13. The upper end opening of the transport container 11 can be closed by a lid 14, and the lid 14 is fixed to the transport container 11 side with a plurality of bolts 15.
16 is nuclear fuel (multi-element bottle) housed in the transport container 11. Reference numeral 17 denotes an annular lid that closes the upper end of the transportation container 11 and the upper end of the bucket bag 5. 18 indicates the water surface.

Normally, an empty bucket 5 is stored submerged at the bottom of the fuel handling pool 1. When the bucket 5 is to be raised, a bucket hoisting yoke (not shown) is attached to the trunnion 9, and the bucket is slowly lifted by a crane. After the bucket 5 is raised to the upper part, the roller 8 of the guided member 6 is moved horizontally along the curved guide surface 3, and the roller 8 is locked and fixed in the locking groove 4. Thereafter, the transportation container 11 carried by the crane is inserted into the bucket 5 to be in the state shown by the phantom lines in FIG. 1, and a sealing lid 17 is attached between the upper ends of the bucket 5 and the transportation container 11. Next, after completing various tasks such as removing most of the numerous bolts 15 that fix the lid 14, except for 2 to 3, the bucket 5 in which the transport container 11 is stored is removed. While lifting, the roller 8 is horizontally moved along the curved guide surface 3 in the opposite direction to that described above, and is fitted into the upper end of the guide groove 2. Then, by loosening the rope of the crane, the bucket
Since the four rollers 8 are guided by the guide grooves 2, they reach the bottom of the fuel handling pool 1 while being maintained in a horizontal state, resulting in the state shown by solid lines in FIG. The nuclear fuel 16 in the transport container 11 is then taken out and stored in a storage pool via a transport waterway. The bucket cart 5 can be raised and lowered very easily in this manner. When the bucket 5 reaches the bottom of the fuel handling pool 1, the four rollers 8
Since these are fitted into the respective guide grooves 2, they will serve to prevent falls from now on.

In the above embodiment, the roller 8 is used as the guided member 6, but a rectangular bar-shaped guided member 6 may also be used as shown in FIGS. 4 to 6. . Further, the number of pairs of guide grooves 2 and guided members 6 may be modified to, for example, six pairs, in addition to the four pairs shown in the embodiment.

According to the method for lifting and lowering a spent fuel transport container of the present invention described above, the following effects can be expected.

Since a crane is used as the Γ drive device, no drive device is required, and the structure of the bucket and fuel handling pool becomes extremely simple.

Although the lifting load of the Γ crane increases by approximately 1/4 of the weight of the loaded transport container, the cost can be significantly reduced compared to when a drive device is installed.

When the Γ bucket is located at the bottom of the fuel handling pool, the rollers fit into the guide grooves, which also serves as a fall prevention function, eliminating the need for a fall prevention device.

Since the Γ structure is simple, the fuel handling pool can be made compact and the space required for installation can be reduced.

Since a guide groove and a guided member are used as the Γ guide means, the bucket can be moved by simply locking the guided member in the locking groove formed continuously at the upper end of the guide groove without providing any special locking device. It can be stably stopped at the rising floating position.

Since the Γ bucket is lifted and lowered while being suspended by a crane, it can be raised and lowered while maintaining a stable horizontal position.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, FIG. 1 is a longitudinal sectional front view, and FIG. 2 is an A--
A sectional view, FIG. 3 is a BB sectional view, FIGS. 4 to 6 show another embodiment, and FIG. 4 is a vertical sectional front view.
FIG. 5 is a sectional view taken along the line CC in FIG. 4, and FIG. 6 is a sectional view taken along the line DD in FIG. 1... Fuel handling pool, 2... Guide groove, 4...
... Locking groove, 5 ... Bucket, 6 ... Guided member, 11 ... Spent fuel transport container, 14 ... Lid body, 16 ... Nuclear fuel, 17 ... Lid.

Claims (1)

[Claims] 1. A plurality of guide grooves are formed on opposing side surfaces of the fuel handling pool, each extending over almost the entire length in the vertical direction, and buckets guided by each of these guide grooves via guided members are inserted into the fuel handling pool. The state in which the bucket is submerged, the bucket is first lifted by a crane and raised to the surface, the guided member is locked in the locking groove continuous to the upper end of each of the guide grooves, and then the spent fuel transport container is stored in the bucket. The space between the upper end of the spent fuel transport container and the upper end of the bucket is closed with an annular lid, and the bucket is lowered and submerged into the fuel handling pool while being suspended by a crane together with the spent fuel transport container. How to raise and lower a spent fuel transport container.