JPS64638Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a storage rack for storing spent fuel in a water-filled pool in a nuclear reactor facility.

Since the spent fuel taken out from the core of a nuclear reactor has high decay heat, it is cooled and stored in a water pool within the facility until the high decay heat is sufficiently attenuated. As this means, the above-mentioned spent fuel storage rack (hereinafter simply referred to as "rack") is used.
Such racks are used to accommodate and support a large number of spent fuels, and are generally required to have sufficient strength as a structure with high earthquake resistance, as well as to have good storage efficiency.

Here, the structure of a conventional rack will be described with reference to FIGS. 1 and 3. In the figure, 1 is a box-shaped rack frame, and the rack frame 1 includes vertical beams 2 placed in the middle of the four corners and each periphery, horizontal beams 3 in multiple upper and lower stages connecting the vertical beams 2,
It is assembled into a rigid frame structure that combines reinforcing beams 4 that act as braces for tilting, support plates 5 for fixing the rack to the bottom wall of the water pool, and central vertical main pillars 6 to increase strength. There is. Further, the rack frame 1 is provided with lattice beams 7 on the upper and lower surfaces, and the lattice beams 7 partition the inner space of the rack frame into a lattice shape, thereby defining a large number of fuel storage chambers 8. Note that a part of the lattice beam 7 also serves as a reinforcing beam that connects the main column 6 and the horizontal beam 3. The spent fuel is transferred from the core to the water pool by a fuel handling machine (not shown), and is lowered from above the rack into the storage chamber 8 at a designated address. Although not shown in the drawings, in the actual rack, members for guiding and supporting the fuel are provided at several locations above and below for each storage chamber 8.

By the way, the lattice beams 7 are arranged parallel to each side of the outer peripheral frame of the rack frame 1 as shown in FIG. The vertical and horizontal pitches of each lattice beam 7 are set with reference to the subcritical pitch P to ensure the necessary separation distance to guarantee subcriticality. Here, the dotted line l in the figure is a vertical and horizontal array virtual line passing through the storage positions of each spent fuel arranged in a grid with the subcritical pitch P as a reference. Note that the vertical support 6 shown in FIG. 1 is omitted from FIG. 3 for illustrative purposes.

By the way, the above-mentioned conventional structure has the following problems. In other words, in addition to the spent fuel mentioned above, there are various types of core waste that are removed from the reactor, and like spent fuel, these core wastes are temporarily stored inside the facility before being transported outside the facility. In particular, it is common practice to store them in racks in water pools along the route of transportation. However, as is clear from FIG. 3, in the conventional rack, the lattice beams 7 are arranged parallel to the imaginary line l of the fuel storage positions drawn with the subcritical pitch P as a reference, and the fuel storage No extra space was formed except for No. 8 to specifically accommodate core waste. For this reason, in order to store the core waste in a rack, it was unavoidable to open up a part of the fuel storage chamber 8 to store the core waste indicated by the reference numeral 10. However, in this method, the spent fuel The capacity will be reduced by the amount of core waste stored, which will impede the storage of spent fuel.

The present invention was made in consideration of the above points, and its purpose is to
Moreover, it is a new type of spent fuel with high storage efficiency that can store the required number of spent fuel and core waste at the same time while ensuring the required subcritical pitch between adjacent fuel storage chambers. The purpose is to provide storage racks.

This purpose is achieved by the present invention, in which the spent fuel is arranged diagonally with respect to the vertical and horizontal imaginary lines passing through the storage positions of the spent fuel arranged in a lattice pattern in the inner space of the rack frame with the subcritical pitch as a reference. This is achieved by providing a lattice beam, which divides a large number of fuel storage chambers in a diagonal direction within the rack frame, and forming a core waste storage chamber between the fuel storage chambers.

The present invention will be described in detail below based on illustrated embodiments.

FIG. 2 shows an external perspective view of an embodiment of the present invention, and FIG. 4 shows a plan view showing its lattice arrangement. The difference between this embodiment and the conventional rack shown in FIGS. 1 and 3 is that, as clearly shown in FIG. They are arranged so as to diagonally cross the vertical and horizontal array imaginary lines 1 passing through the storage positions of the spent fuels 9 arranged in a grid pattern similarly drawn. That is, each lattice beam 7 extends parallel to the diagonal of the box-shaped rack frame 1. Due to this diagonal arrangement of the lattice beams 7,
There is a subcritical pitch P in the inner space of the rack frame 1.
While ensuring the same number of fuel storage chambers 8 as shown in FIG.
A storage chamber 11 that can be used as a storage space is divided into sections. Note that in FIG. 3, a dedicated storage chamber for the core waste 10 cannot be formed because the vertical and horizontal lattice beams intersect exactly at the location where the storage chamber 11 in FIG. 4 is located.
Therefore, despite the same external dimensions as before, the required number of spent fuel can be stored in a subcritical pit, and core waste can be stored in the fuel storage chamber 8.
It can be stored in the dedicated storage chamber 11 without using any part of the storage space, and the practical benefit is extremely large.

[Brief explanation of the drawing]

1 and 2 are external perspective views of a conventional spent fuel storage rack and an embodiment of the present invention, respectively, and FIGS. 3 and 4 are storage racks for spent fuel, etc. in FIGS. 1 and 2, respectively. FIG. 3 is a schematic plan view showing the arrangement. 1... Box-shaped rack frame, 7... Lattice beam,
8...Fuel storage chamber, 9...Spent fuel, 10...
Core waste, 11...core waste storage chamber.

Claims (1)

[Scope of utility model registration request] For nuclear reactors, lattice beams are arranged in a box-shaped rack frame to partition the inner space of the rack frame into a lattice pattern, forming a number of fuel storage chambers between adjacent spaces to ensure subcritical pitches for spent fuel. In a spent fuel storage rack, grids are arranged diagonally with respect to vertical and horizontal imaginary lines that pass through the storage positions of each spent fuel arranged in a lattice pattern in the inner space of the rack frame with the subcritical pitch as a reference. The lattice beam is used to partition a large number of fuel storage chambers in a diagonal direction within the rack frame, and at this time, a core waste storage chamber is formed between each of the fuel storage chambers. Storage rack for spent fuel for furnaces.