JPH05164883A - Spent fuel storing rack - Google Patents

Abstract

PURPOSE:To provide a spent fuel storing rack high in both working accuracy and reliability while manufacturing manhours are reduced by providing projected pieces for the corner section of each rectangular cylinder with each rectangular cylinder cut off at its corner section. CONSTITUTION:In a used fuel storing rack where a plural number of rectangular cylinders 10 is arranged in a diced pattern, and spent fuel is stored in spaces which are formed by both the inside of each rectangular cylinder 10 and relative spaces among the rectangular cylinders 10 as a spent fuel housing cell, while the rectangular cylinders are lined up in an upright condition. Each rectangular cylinder 10 is made of stainless steel added with neutron absorber, and is provided with a plural number of projected pieces at its corner section, which is formed with each rectangular cylinder 10 cut out along its longer direction. And the respective rectangular cylinders 10 are fixed in specifically spaced relation with the projected pieces of the adjacent rectangular cylinders 10 welded together, so that a plural number of fuel housing cells 4, 5 and 6 is formed so as to be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spent fuel storage rack for storing spent fuel taken out from a nuclear reactor.

Generally, in a nuclear power plant, spent fuel taken out from a nuclear reactor core is temporarily stored until reprocessing, and the storage is stored in a spent fuel storage pool (hereinafter abbreviated as pool). It is stored in the installed spent fuel storage rack and cooled and stored.

[0003]

2. Description of the Related Art In recent years, various improvements have been made to reduce the interval between spent fuels stored in order to effectively use the space in the pool. However, in such a rack, in order to maintain the subcriticality of spent fuel,
It is necessary to interpose a material with a large neutron absorption capacity between fuels, and to have sufficient strength to safely hold the spent fuel against vibrations during an earthquake. It is said that.

Conventionally, a structure having a structure in which a plurality of preformed square cylinders are bundled and combined is adopted because such conditions are satisfied and the manufacture is easy. Many of these prisms are made of boron-added stainless steel that contains neutron absorbers having excellent neutron absorption capability, such as boron, and has sufficient strength.

That is, this spent fuel storage rack is shown in FIG.
As shown in the plan view of FIG. 1, a plurality of boron-added stainless steel square tubes 2 are arranged in a checkered pattern on a base 1, and an outer space portion is closed by an outer plate 3. The cylinder 2 has its lower portion fixed to the base 1.

As a result, the spent fuel in the shape of a rectangular tube (not shown) is formed by the first fuel storage cell 4 formed on the inner circumference of the rectangular tube 2 alone and the outside of each of the four rectangular tubes 2 in the front-rear, left-right direction. A second fuel storage cell 5 surrounded by a wall and a third fuel storage cell surrounded by side walls of three square tubes 2 with only one of the front, rear, left and right directions being an outer plate 3. It is designed to be inserted and stored in the cell 6.

The fuel storage cells 4, 5 and 6 are
As shown in the plan view of the main part of the square tube connection of FIG. 9, the square tubes 2 are connected to each other at the corners thereof by fillet welding via the L-shaped connecting member 7. The size of the fuel storage cells 4, 5, 6 formed by this is that the spent fuel can be stored without any problem in consideration of the dimensional accuracy of the spent fuel itself to be stored, as well as the bending and swelling due to neutron irradiation. Must be dimensioned.

On the other hand, in consideration of the space efficiency in the pool of the spent fuel storage rack, each fuel storage cell 4, 5,
There is also a demand for making the dimensions of 6 as small as possible, and these dimensions are required to have high accuracy.

[0009]

When the spent fuel storage rack is manufactured, particularly when welding the square tubes 2 together, the square tubes 2 may be deformed due to welding heat input to the square tubes 2. In order to prevent it and maintain the required accuracy, various jigs are used and careful attention is paid. Therefore, there is a problem that a large amount of manufacturing man-hours, jigs and tools, and equipment are expensive. Therefore, the deformation due to welding heat input is small, the man-hours for correcting the welding distortion are reduced, and the welding for connecting the rectangular cylinders 2 is performed. There was a problem of reducing the absolute amount and the number of manufacturing steps.

An object of the present invention is to provide a projecting piece by notching the square tube at a corner portion of each square tube, and welding the projecting pieces to connect the square tubes to reduce the number of manufacturing steps.
It is to provide a spent fuel storage rack with high processing accuracy and high reliability.

[0011]

[Means for Solving the Problems] A plurality of square tubes are arranged in a checkered pattern, and the spaces formed in the square tubes and between the square tubes are used as fuel storage cells to store spent fuel, respectively, and are aligned in an upright state. In the spent fuel storage rack to be stored, the square cylinders are made of stainless steel to which a neutron absorber is added, and each corner part is provided with a plurality of protruding pieces that are notched and protruded along the longitudinal direction of the square cylinders and are adjacent to each other. A plurality of fuel storage cells are formed by welding the projecting pieces of the square tubes and fixing the square tubes to each other at a required interval.

[0012]

In the spent fuel storage rack of the present invention, a plurality of square tubes made of stainless steel to which a neutron absorber is added are arranged in a checkered pattern at required intervals, and the square tubes of each square tube are arranged along the longitudinal direction. A plurality of projecting pieces provided by notching the corners are welded together to form a plurality of fuel storage cells. At this time, by connecting the square tubes by a plurality of projecting pieces provided by cutting out the corners of the square tube, the intervals are set by the abutment of the projecting pieces, and the welding applied to the square tube at the time of welding. Since the influence of heat distortion due to heat input is small, high dimensional accuracy can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same reference numerals are given to the same structural parts as those of the above-described conventional art, and detailed description thereof will be omitted.

The spent fuel storage rack is a plan view of FIG.
As shown in the front view of FIG. 2, a plurality of boron-added stainless steel square tubes 10 are arranged in a checkered pattern on the base 1, and the outer space is closed by the outer plate 3. The lower portions of the square tubes 10 are fixed to the base 1.

As a result, the spent fuel in the shape of a rectangular tube (not shown) is formed by the first fuel storage cell 4 formed on the inner periphery of the single rectangular tube 10 and the outside of each of the four rectangular tubes 10 in the front, rear, left and right directions. The second fuel storage cell 5 surrounded by the wall, and the third fuel surrounded by the outer walls of the three rectangular tubes 10 in addition to the outer plate 3 in only one of the front, rear, left, and right directions. The cells are stored in the storage cells 6, respectively.

As shown in the plan view of the connection of the main parts of the square tube of FIG. 3 and the perspective view of the main parts of the square tube of FIG.
A projecting piece (11) is provided by cutting out a part of the square tube (10) itself at a corner portion of (10). The cut-out traces are cutout holes 12.

Further, the rectangular cylinders 10 arranged in a checkered pattern are connected by butt-welding the protruding pieces 11 of adjacent corner portions that abut each other. Further, at the outermost periphery of the connected square cylinders 10, the protruding pieces 11 facing each other are butt welded by a tie plate 13 at the portions where the square cylinders 10 are separated from each other, and the outer plate 3 is arranged on the outside thereof. The fillet is welded to the cylinder 10, and the square cylinder 10, the tie plate 13, and the outer plate 3 are arranged in a standing manner. Next, the operation of the above configuration will be described.

The connection of the plurality of rectangular tubes 10 forming the fuel storage cells of the spent fuel storage rack is performed by butt welding the projecting pieces 11 protruding from the corners of the rectangular tube 10 so that the rectangular tube 10 is connected. Compared to the case where fillet welding is performed at the corners, the welding heat input to the square tube 10 is extremely small, the welding work is easy, and the weld joint efficiency, which was 0.6 in conventional fillet welding, is improved. It is greatly improved to 0.9. This welded joint efficiency is the evaluation strength when welding the mutual members, and is evaluated as 1.0 for materials that are not welded.
As a result, the welding amount required to obtain the same strength as that of the conventional one is small, and the deformation amount of the square tube 10 itself due to the welding thermal strain is further reduced. Therefore, various jigs and tools for maintaining the required manufacturing accuracy can be simplified, and the manufacturing cost, man-hours for attaching and detaching and welding man-hours can be reduced.

In the above embodiment, the material of the rectangular tube 10 forming the fuel storage cells 4, 5 and 6 is made of boron-added stainless steel containing boron, which is a substance having good neutron absorption. Adds rare earth elements (scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium), which have excellent neutron absorption capacity similar to boron. The same action and effect can be obtained by using the stainless steel.

The plan view of FIG. 5, the enlarged plan view of the main portion of the square tube connecting portion of FIG. 6 and the perspective view of the main portion of the square tube portion of FIG. 7 show another embodiment of the present invention. As shown in FIGS. 6 and 7, the protruding direction of the projecting piece, which is formed by cutting out a part of the corner portion of the square tube 14 itself, is alternately different in the longitudinal direction of the square tube 14 as a configuration for connecting the two. ..

That is, the uppermost protruding piece 15 and the next protruding piece 16
Have their directions perpendicular to each other, and the protruding pieces 15 in the third step are projected in the same direction as the uppermost protruding piece 15. As shown in FIG. 6, the rectangular tubes 14 are connected to each other by the rectangular tubes 14 that are adjacent to each other at the corners, and the projecting pieces 15 that come into contact with each other,
By associating the projecting pieces 16 with each other, the intervals between the square tubes 14 are set, and then by butt welding, a plurality of fuel storage cells 5 are formed.

Further, regarding the outermost square tube 14, adjacent projecting pieces 15 and projecting pieces 16a are butt-welded together by a tie plate 13, and the outer plate 3 is formed on the square tube 14 on the outside thereof. Square tube 14, tie plate by welding
The outer plate 3 and the outer plate 3 are vertically arranged.

In addition, since the protruding pieces 15 and the protruding pieces 16 are welded and connected to each other at right angles to each other in the rectangular tube 14, the rigidity is stronger than that of the above-mentioned one embodiment, but the others are the same. You can obtain various actions and effects.

[0024]

As described above, according to the present invention, welding work is easy at the time of connecting two rectangular cylinders together, the connection strength is improved, and
Since the influence of welding heat input is small, dimensional accuracy is improved. Therefore, the storage density of the spent fuel and the strength of the spent fuel storage rack are increased, and the manufacturing man-hours are reduced, so that the price is low and the reliability is improved.

[Brief description of drawings]

FIG. 1 is a plan view of a spent fuel storage rack according to an embodiment of the present invention.

FIG. 2 is a front view of a spent fuel storage rack according to an embodiment of the present invention.

FIG. 3 is a plan view of a main portion of a square tube connection according to an embodiment of the present invention.

FIG. 4 is a perspective view of a main part of a rectangular tube according to an embodiment of the present invention.

FIG. 5 is a plan view of a spent fuel storage rack according to another embodiment of the present invention.

FIG. 6 is an enlarged plan view of a main part of a square tube connection according to another embodiment of the present invention.

FIG. 7 is a perspective view of a main part of a rectangular tube according to another embodiment of the present invention.

FIG. 8 is a plan view of a conventional spent fuel storage rack.

FIG. 9 is a plan view of a conventional rectangular tube connection main part.

[Explanation of symbols]

1 ... Base, 3 ... Outer side plate, 4 ... First fuel storage cell, 5
... second fuel storage cell, 6 ... third fuel storage cell, 10,
14… Square tube, 11,15,16… Projecting piece, 13… Tie plate.

Claims (1)

[Claims] 1. A plurality of square tubes are arranged in a checkered pattern, and a space formed inside the square tubes and between the square tubes is used as a fuel storage cell. Spent fuel is stored in each of the square tubes in an upright state. In the fuel storage rack, the square tube is made of stainless steel to which a neutron absorber is added, and a plurality of projecting pieces are formed by notching and projecting the square tube along the longitudinal direction at each corner.
A spent fuel storage rack, characterized in that a plurality of fuel storage cells are formed by welding adjacent projecting pieces of adjacent rectangular cylinders and fixing the rectangular cylinders at a predetermined interval.