JPS61160092A - Storage basket for fuel aggregate - 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 [Field of Application of the Invention] The present invention relates to a storage basket for storing spent fuel assemblies generated in a nuclear power plant, in particular for dissimilar fuel assemblies, such as boiling water type. The present invention relates to a storage basket that can be shared by spent fuel assemblies generated from nuclear reactors and pressurized water reactors.

[Background of the invention]

Spent fuel assemblies generated at nuclear power plants are temporarily stored in a spent fuel storage pool (hereinafter referred to as a fuel boule) inside the nuclear power plant building, then transported to a reprocessing plant, and then It is stored in a reprocessing plant in a fuel boule and cooled until reprocessing.

By the way, the external dimensions of the fuel assemblies of boiling water reactors (hereinafter referred to as m) and pressurized water reactors (hereinafter referred to as m) are as follows:
The original one is about 140 x 140 mm, p%111R (7)
It is very different from 214x214mm. Conventionally, reprocessing plants use at least two types of dedicated storage equipment, one for fuel assemblies and the other for PWR fuel assemblies, but by grouping several fuel assemblies together, operation and transfer times can be shortened. In order to share the storage equipment, the external dimensions of the dedicated storage baskets for each fuel assembly are made to be the same.

An example of such a dedicated basket according to the prior art is shown in FIG. 4, which is a top view, and FIG. 5, which is a perspective view. In these figures, (&) indicates the storage basket for the 1st fuel assembly, and (b) indicates the storage basket for the m fuel assembly.

As shown in the figure, the storage basket according to the prior art has a base of 3
It has a structure in which a pie f4 for storing fuel assemblies is welded to the top. 3' is a spacer plate for holding the armrests 4 together. This storage basket, in which fuel assemblies are housed in each /f igument 4, is designed to store different types of fuel assemblies such as m and PWR in the same fuel boule. 3' have the same external dimensions so that transportation and storage facilities can be shared. An example of such a storage basket is NUCLKARTECHNOLO, Volume 43, Midway Grill, 1979.
GY VOL.

43 MID-APR, I 979), pages 146 to 149-e.

In this way, by adopting a structure in which the base 3 and the spacer 3' have the same external dimensions, the storage ratio of m-fuel and m-fuel in the fuel pool can be changed by changing the storage basket. This has the advantage that it is only necessary to change the stored fuel.

However, when fuel is stored in all of the storage capacity of the fuel pool, the storage ratio of fuel in the fuel pool cannot be changed unless the storage basket other than the storage basket in the fuel pool is used. . For example, if the number of storage baskets in the fuel pool is set such that the current storage ratio is 50% for lagoon fuel and 50% for PWR fuel, then for some reason, t-60% of m fuel must be stored. If the storage basket for BWR fuel assemblies is already contaminated with reed radiation in the fuel pool, then store it somewhere else, and then abandon the storage basket for BWR fuel assemblies into the fuel pool water. There must be. Additionally, the storage basket for the 4PWR fuel assembly was immersed in contaminated water in the fuel pool, so before it can be removed from the fuel pool, it must be decontaminated and stored under strict radiation control. In addition, if the fuel is to be stored underwater in the fuel pool, it must be stored in another space (for example, a reserve pool) separate from the storage space.

In this way, with the conventional technology that uses dedicated storage baskets for the same fuel assembly and the m fuel assembly, decontamination equipment and management equipment are required when changing the fuel storage ratio, or the fuel Since a pool other than the swimming pool, such as a backup pool, is required, there is a problem in that the impact on the facility becomes large.

[Purpose of the invention]

The object of the present invention is to provide spent fuel assemblies of different external sizes,
It is an object of the present invention to provide a fuel assembly storage basket that can be shared for spent fuel assemblies produced by, for example, BWR and m.

[Summary of the invention]

The present invention provides an internal partition plate of a storage basket with a plurality of vertical notches corresponding to the external sizes of different fuel assemblies up to the middle of the partition plate, and selectively separates the partition plates perpendicular to the notches. The size of the lattice-shaped storage compartments formed by the mating matches the external size of one type of fuel assembly when storing the fuel assemblies, and the external size of the storage compartment when storing the other type of fuel assemblies. This design allows different types of fuel assemblies to be stored in the same storage basket rather than changing the fitting position of the notch.

[Embodiments of the invention]

Embodiments of the storage basket of the present invention are shown below in Figures 1 to 3.
This will be explained using figures.

FIG. 1 is a top view, and FIG. 2 is an elevational cross-sectional view taken along line A-A.
In these figures, (&) indicates a case in which a lattice f:m is used for storing m fuel assemblies, and (b) indicates a case in which a lattice for storing m fuel assemblies is assembled.

FIG. 3 shows an elevational view of the partition 2 of the storage basket.

The storage basket consists of a prismatic storage basket body 1, two sets of four partition plates 2, and a bottom plate 6. The partition plate 2 has a notch 5 extending to one-half of its total length. The width of this cut 5 is slightly larger than the thickness of the partition plate 2. The main body 1 and the partition plate 2 are made of stainless steel SUS 304 containing a neutron absorbing material such as Geron. Partition plate 2
Four notches 5 are provided as shown in FIG. The positions of these notches 5 are as shown in Figure 3 for BWR fuel assembly storage, so that the dimensions b' and b'' are all equal, and for PwR fuel assembly storage. Therefore, the dimensions a and a' shown in Fig. 3 are selected so that they are equal, and the dimensions b and b are
', b' are set to be slightly larger than the thickness of the m fuel assembly (140mm), and dimensions &, &' are set to be slightly larger than the thickness of the m fuel assembly (214mm!J). There is.

Cut two of each of the four partition plates 2 with this cut 5,
As shown in (&) in FIGS. 1 and 2, the notches 5 are assembled in the basket body 1 so that the directions of the notches 5 are upside down, and the notches are fitted into each other. It is possible to form nine compartments for storing m fuel assemblies, or four compartments for storing m fuel assemblies as shown in FIG.

Of course, the basket body l is made to the dimensions necessary to form these compartments. The basket body has a structure in which a bottom plate 6 is attached as shown in FIG. 2.

The bottom plate 6 is provided with a lower guide hole 7 for the BWR fuel assembly, through which the pool water in the fuel boule can be circulated inside the storage/muskerat. Lower guide hole 7 is required for BWR fuel assembly, but PW
Since the lower part of the R fuel assembly is flat, the guide hole 7 is not necessary for the M fuel assembly.

An example of the fuel storage method according to this embodiment will be explained below.

First, nine spent fuel assemblies that have been transported to a spent fuel storage facility, regardless of whether they are for m or It is placed in a storage basket and transported to a storage area. After being cooled and stored in a storage area for a certain period of time, the fuel is transferred to the main reprocessing process. After 7, the empty storage basket is filled with fuel assemblies again and stored in the vacant space in the storage area. This operation is repeated thereafter.

For example, the storage basket that has been sent and returned from the storage area is
If the fuel to be newly stored in this storage basket is an m fuel assembly in the case where the storage basket is assembled for WR fuel, the storage basket is temporarily removed from the fuel pool, and then the partition plate 2 The storage basket body
By fitting the partition plate 2 into the notches 5 made at the positions having the dimensions a and a' in FIG.
wThe fuel assembly can be stored.

Moreover, by removing the partition plate 2 from the storage basket main body 1, crud accumulated in the storage basket main body 1 can be easily removed using an underwater vacuum cleaner or the like.

The storage basket is designed so that the fuel does not reach criticality while in storage. In other words, in this example, subcriticality is maintained by adjusting the thickness of the partition plate 2 and the concentration of a neutron absorbing material such as Garon in the partition plate 2 while m fuel is stored. do. In addition, in the storage state of PwR fuel, subcriticality is maintained by the two partition plates 2 mentioned above and the fuel pool water between the partition plates 20. The storage pitch is determined so that it is subcritical and has a large storage density. Although neutron leakage occurs due to the notch 5, the influence is minimal and subcriticality is maintained sufficiently.

When the partition plate 2 contains a neutron absorbing material, by replacing it with a partition plate 2 with a different concentration of neutron absorbing material, it is possible to cope with future high concentration degeneracy fuels, and the storage basket main body can be changed. There's no need. Moreover, when the partition plate 2 that is replaced and becomes unnecessary can be disassembled, the volume becomes small and storage becomes easy.

The effect of the difference in length between m-fuel and m-fuel on criticality is:
If the PWA fuel is designed with a long length, that length can cover the effective fuel length of the BWR fuel, and subcriticality can be maintained.

The above embodiment is schematically illustrated as pasta.

The partition plates 2 were rearranged in the main body 1 as shown in Figs. 6(,) and (b), but even more partition plates 2
as shown in Figure 7 (a) p (b) or as shown in Figure 8 (a)
It is also possible to rearrange the fuel assembly as shown in (b) to form compartments of different sizes depending on the size of the fuel assembly. Furthermore, when reassembling, instead of placing two adjacent partition plates close together to form a partition wall as shown in the above figure, depending on the size of the fuel assembly to be accommodated, two adjacent partition plates may be used. It is also possible to implement an embodiment in which the above-mentioned partition sheet metal layers are placed close to each other to form a section wall. Furthermore, the present invention is applicable even when the basket body 1 has a rectangular cross section instead of a square (however, in this case, the front-rear partition plate and the left-right partition plate must be distinguished).

〔Effect of the invention〕

According to the present invention, it is possible to change the mutual fitting position of the notch provided in the partition plate of the storage basket according to the external size of the fuel assembly to be stored and the partition plate, so that different types of fuel assemblies can be stored in the same storage basket. You can store your body. For example, both the m fuel assembly and the m fuel assembly can be stored in the same storage space by rearranging the lattice of the partition plate. Therefore, when changing the storage ratio of a storage facility, the same storage basket can be used by rearranging the partition plates inside the storage basket, thereby reducing the amount of waste generated.

Furthermore, if crud or the like accumulates inside the storage basket main body, the inside of the storage basket can be easily decontaminated by simply removing the partition plate.

If the size of the fuel assembly changes in the future, it is possible to accommodate the new size of the fuel assembly by removing the partition plate and replacing it with a partition plate with new notches. .

[Brief explanation of the drawing]

Figures 1(a) and 2(a) and 2(b) are a top view and an elevational sectional view showing an embodiment of the present invention in which the method of assembling the partition plates is changed, respectively, and Figure 3 is a corresponding Elevation of the partition plate,
Figures 4(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a) and 5(a), and 5(a) and 5) and 6(a) and 6(b) and 6(b) and 6. Figure 7(a)
e (b) and FIG. 8 (→. (b) is a top view schematically showing the rearrangement of partition plates in different embodiments of the present invention. 1... Storage basket main body 2... Partition plate 3...
Base 3'...Spacer plate 4...
Bye 5...notch 6...bottom plate
7...Guide hole, -

Claims (1)

[Claims] A storage basket body having a square cross section and a bottom wall, and a plurality of notches reaching halfway in the vertical direction are formed at positions corresponding to the external sizes of different types of fuel assemblies to be stored. a plurality of recombinable storage basket bodies perpendicular to each other so as to selectively interfit with each other to form a plurality of storage compartments corresponding to the external sizes of the different types of fuel assemblies; A fuel assembly storage basket comprising: a plurality of partition plates;