JPS6159292A - Rack for storage - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a fuel storage tank provided in a nuclear reactor building.
This relates to storage racks used to store fuel assemblies and control rods.

[Technical Background of the Invention and Problems Therewith] A fuel assembly for a boiling water reactor (BWR) is constructed by arranging a large number of fuel rods in a lattice shape within a channel box having a substantially square cross section. In addition, the control rod that is inserted into and removed from the cross-shaped gap formed by the four adjacent bodies has a sheath with a deep U-shaped cross section attached to each protruding leg of a tie rod with a cross-shaped cross section.
It is constructed by loading a large number of neutron absorption rods into each sheath.

The upper end of the control rod is provided with a tip structure that also serves as a handle, and the lower end is provided with a lower skirt that has a disc-shaped speed limiter at the lower end.

Spent fuel assemblies and spent control rods are stored in fuel storage pools for long periods of time, and conventionally, the following storage racks have been used to store them. That is, as a rack for fuel assemblies, a rack having a rectangular cylindrical shape and having partitions on both sides of the inside for engaging the fuel assemblies with holes with a water gap in the longitudinal direction of the cross section is used. As the speed limiter, a cylindrical one with a 1gi surface shape is used, which allows the disc-shaped speed limiters to be accommodated in a state where they are aligned and in contact with each other.

However, as nuclear fuel reprocessing has been delayed, it has become necessary to store more spent fuel assemblies in fuel storage pools. Racks have come into use, and wall-mounted storage racks mounted on pool walls have come into use.

However, in order to maintain a fuel assembly housed in a dense storage rack in a subcritical state, a relatively expensive neutron absorbing material must be used as the rack material, making the rack expensive. Also, the wall-mounted control rod storage rack does not allow a fuel storage rack to be placed underneath it, thereby reducing the effective floor area of the pool.

[Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and provides a storage method that allows fuel assemblies to be stored densely while keeping them subcritical, is inexpensive, and can effectively utilize the floor space of a fuel storage pool. The purpose is to obtain a rack for use.

[Summary of the Invention] The storage rack of the present invention includes a rectangular cylindrical frame, a partition plate that divides the inside of the frame into a rectangular first lattice larger than twice the cross-sectional area of the fuel assembly, and a fuel assembly. a partition plate partitioning into a second square grid having a cross-sectional area larger than four times the cross-sectional area of the storage channel; and a storage channel disposed at two locations within the first grid;
The present invention is characterized in that it has a partition support provided on each partition plate of the second lattice.

[Embodiment of the Invention] In FIGS. 1 and 2, a cylindrical frame 1 with a rectangular cross section is provided with a partition 2.3 at a position dividing the short side into three equal parts. In the space between 3 and the side wall of frame 1, partition plates 2 and 3 are installed at positions that divide the long side into 10 equal parts.
In the space between, partition plates 4 are installed at positions that divide the long side into 5 equal parts.
．． 5 and 6 are provided. Further, on the opposing surfaces of the partition plates 2 and 3, a control having an arcuate groove at the tip is located in the center of the side of the lattice formed by the side plates of the frame 1 and the partition plate 4 perpendicular to them. A rod wing support 7°8 is provided. Further, similar control rod wing supports 9 and 10 are provided on the partition plate 6 and the side plates of the frame 1.

Further, within the elongated rectangular lattice formed by one side plate of the frame 1 and the partition plates 2 and 4, and the other side plate of the frame 1 and the partition plates 3 and 5, there are fuel storage channels 11 each having a substantially square cross section. It is a provision. Note that a gap 12 is provided between each fuel storage channel so that a water gap parallel to the partition plate 2.3 is formed.

Further, as shown in FIG. 2, a seat 13 is provided at the bottom of each fuel storage channel 11 to engage with the lower end of the fuel assembly. Furthermore, for the square lattice divided by the frame 1 side plate and the partition plates 2 and 3.6, after inserting the IIJtllJ114 into these lattices, it is placed on the speed limiter 14a of the control rod and the fuel assembly is placed on the upper surface. There are four catches 15 that engage the lower end of the handle.

In the storage rack of the present invention having the above structure, the frame 1 is made of a neutron absorbing material in order to avoid criticality with the stored fuel assemblies in adjacent racks.

Fuel assemblies and control rods are stored as shown in FIG. That is, the rack of the present invention is immersed in a fuel storage pool, and a fuel assembly 16 is placed in each fuel storage channel 11.
, the control rod 14 is first inserted into the lattice formed by the partition plates 2, 3, 6, etc., and the blade is attached to the blade support 7.8.
9.10. The speed limiter 14a is supported by the speed limiter 14a.
Support seats 15 are placed on top, arranged at each blade gap angle, and the fuel assembly 16 is supported by these seats.

When stored as described above, gaps 12 are formed between the fuel assemblies housed in the storage channel 11 and between fuel assemblies adjacent to each other, and fuel assemblies are stored between the partition plates 2 and 3. Since one control rod is placed in every four fuel assemblies, even if the fuel assemblies are stored in a relatively narrow place, they will not reach criticality.

Note that the present invention is not limited to the above embodiments. In the above embodiment, one control rod is arranged and stored for every 12 fuel assemblies, but this is in accordance with the ratio of fuel assemblies to control rods in a general BWR. Of course, the ratio can be arbitrarily selected.

[Effects of the Invention] According to the present invention, fuel assemblies and control rods can be stored together, so storage space can be reduced.

Additionally, since control rods are stored together, criticality safety is improved. In addition, if the criticality safety is at the same level as conventional storage racks, it is possible to construct storage racks that are more dense than conventional storage racks, making it possible to downsize fuel pools and reactor buildings. can. Furthermore, it is not necessary to construct the storage channel from a material containing a relatively expensive neutron absorbing material, which has a large economical effect.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a cutaway front view thereof. 1... Frame 2.3.4.5... Partition plate 7.8.9.10... Wing plate support 11... Storage channel 12'... Gap 13.1
5...Support seat 14...Control rod 16...Fuel assembly application agent

Claims (1)

[Claims] A rectangular cylindrical frame, a partition plate that divides the inside of the frame into a rectangular first lattice larger than twice the cross-sectional area of the fuel assembly, and a square second grid larger than four times the cross-sectional area of the fuel assembly. A storage device characterized by having a partition plate dividing into a lattice, storage channels arranged at two locations in the first lattice, and wing plate supports provided on each partition plate, etc. of the second lattice. rack.