JPH08248181A - Storage facility of spent nuclear fuel - Google Patents

Abstract

PURPOSE: To prevent the extra force from working on a rack support plate to pit side walls even with the generation of thermal expansion of the rack support plate due to heat decay of fuel in a storage facility of spent nuclear fuel. CONSTITUTION: Provided are a pit 1 storing cooling water, a multitude of rack cells 2 containing spent nuclear fuel in the pit 1 and a plurality of almost horizontal rack support plates 3 connecting and supporting the rack cells 2. A gap G of width permitting the thermal expansion of the rack support plates 3 is formed in between the periphery 3a of the rack support plates 3 and the pit side walls 1a and also a plurality of notches 4 is formed on the periphery of the rack support plates 3. At this notch 4, a joint part 5 connecting the rack support plates 3 to the pit side walls 1a movably in vertical and horizontal directions is placed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spent nuclear fuel storage facility using a high density rack.

[0002]

2. Description of the Related Art A nuclear fuel used in a nuclear reactor is stored in water in a storage pit for a certain period because it has decay heat due to radioactive substances immediately after being taken out from the nuclear reactor.
This storage pit is equipped with a rack that can accommodate multiple nuclear fuels by assembling cylindrical cells or angles, but the spacing between fuels should be a certain distance or more considering criticality. It is like this.

By the way, in recent years, the storage capacity has been enhanced by combining a neutron absorbing material with this spent fuel storage rack and adopting a so-called high-density rack having a narrower space than before. In such a rack, a worker cannot enter because the cell interval is narrow, and therefore a method of fixing the rack to the bottom of the pit cannot be adopted. Therefore, the rack is generally supported by the wall surface of the pit.

In a conventional high-density rack, as shown in FIG. 5, two upper and lower rack support plates 7 each having a hole 2a for inserting a rack cell 2 are assembled by using columns S so that each of them is horizontal. The rack support plate 7 is supported so as to be fixed from the pit side wall 1a through an embedded plate 8 fixed to the pit side wall 1a.

[0005]

However, since the spent fuel rack contains the spent fuel, the temperature of the spent fuel rack rises due to the decay heat of the spent fuel and the thermal expansion occurs. At this time, if the rack support plate is fixed to the side wall of the pit as described above, there is a problem that an excessive force is applied to the side wall of the pit.

The present invention copes with the above-mentioned situation, and in the spent fuel storage facility, by finding a new structure at the joint between the rack support plate and the pit side wall, the thermal expansion of the rack can be achieved. The purpose is not to give extra force to the side wall of the pit.

[0007]

That is, the feature of the spent nuclear fuel storage facility of the present invention that meets the above-mentioned object is that a pit for storing cooling water and a spent atom disposed substantially vertically in the pit are used. In a storage facility comprising a large number of rack cells for containing fuel and a plurality of substantially horizontal rack support plates for connecting and supporting the rack cells, a rack is provided between the outer peripheral edge of the rack support plate and the side wall of the pit. A gap having a width that allows thermal expansion of the support plate is formed, and a plurality of cutouts are formed in the outer peripheral portion of the rack support plate, and the rack support plate can be moved vertically and horizontally in the cutouts. There is a joint member connected to the side wall of the pit.

Further, in the storage equipment of the present invention, it is possible to use a ball coupling for the joint member.

[0009]

In the storage facility of the present invention, even if the rack supporting plate expands due to the decay heat of the spent fuel, the gap formed between the side wall of the pit and the joint member causes the rack supporting plate to expand due to the expansion. It is possible to allow the extension and displacement of the pits to thereby prevent the action of force on the side wall of the pit due to the thermal expansion of the rack.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an enlarged view of a main part showing a storage facility for spent nuclear fuel according to an embodiment of the present invention, FIG. 2 is a partial plan view showing the storage facility, and FIG. 3 is a perspective view showing the same.

The storage equipment of the above-described embodiment of the present invention comprises a pit 1 for storing cooling water, a large number of rack cells 2 arranged substantially vertically in the pit 1 for storing spent nuclear fuel, and the rack cell 2. The rack support plate 3 includes two substantially horizontal rack support plates 3 that are connected and supported by being fitted into a large number of insertion openings 2a.

On the other hand, in the spent fuel storage rack, due to the structure of the fuel handling facility, there is a slight space between the side wall 1a of the pit 1 and the fuel which cannot be handled. Are using.

That is, as shown in FIG. 1, gaps G are formed between the outer peripheral edge portions 3a of the upper and lower rack support plates 3 and the pit side walls 1a, each having a width that allows thermal expansion of the rack support plates 3. The rack supporting plate 3 is attached to
A plurality of notches 4 are formed as shown in FIG. And
In these notches 4, a universal shaft joint-shaped joint member 5 that is connected to the pit side wall 1a is arranged so that the rack support plate 3 can move vertically and horizontally. The gap G, the notch 4, and the joint member 5 are formed over the entire circumference of the rack support plate 3.

In the joint member 5, the fork portion 5a pivotally mounted on the pit side wall 1a and the rack support plate 3 respectively pivots in the horizontal direction, and the arm portion 5b for joining the two fork portions 5a is 3a. The two joints can rotate vertically. As shown in FIG. 4, the joint member 5 includes a joint member 6 in which two fork portions 6a are joined by two pantograph-shaped arm portions 6b, or a ball coupling (not shown) having a ball joint. It can also be configured by using. It is also possible to provide three or more rack support plates 3.

Therefore, in the storage facility of the embodiment of the present invention, even when the rack support plate 3 expands due to the decay heat of the spent fuel, the gap G formed between the pit side wall 1a and the joint member 5 is formed. Alternatively, 6 allows the expansion and displacement of the rack support plate 3 due to the expansion, thereby preventing the action of force on the pit side wall 1a due to the thermal expansion of the rack.

When lateral acceleration is applied to the rack support plate 3 during an earthquake, the rack support plate 3 is slightly displaced.
In the state shown in (1), when the acceleration that separates from the side wall 1a occurs, the joint member 5 or 6 is in a fully extended state and is supported in the horizontal direction. On the contrary, when acceleration that is displaced toward the side wall 1a is applied, the rack support plate 3
The joint member on the opposite side of the rack support plate 3 is fully extended, and the rack support plate 3 is similarly supported in the horizontal direction.

Although the embodiment of the present invention has been described above, the vertical support of the rack support plate 3 can be carried by the support column S shown in FIG.

[0019]

As described above, the spent nuclear fuel storage facility of the present invention has a width between the outer peripheral edge of the rack support plate and the side wall of the pit, which allows thermal expansion of the rack support plate. Along with forming the gap, a plurality of cutouts are formed on the outer peripheral portion of the rack support plate, and a joint member for connecting the rack support plate to the pit side wall so as to be movable in the vertical and horizontal directions is arranged in the cutout. Even if the rack support plate expands due to the decay heat of the spent fuel, the gap formed between the side wall of the pit and the joint member causes the expansion and displacement of the rack support plate due to the expansion. It is possible to prevent the action of force on the side wall of the pit due to the thermal expansion of the rack, and when the rack support plate rolls due to an earthquake or the like, adjust the fully extended length of the joint member. By doing In which a marked effect of preventing interference with the click support plate and the pit side wall.

[Brief description of drawings]

FIG. 1 is an enlarged view of essential parts showing a storage facility for spent nuclear fuel according to an embodiment of the present invention.

FIG. 2 is a partial plan view showing the storage facility.

FIG. 3 is a partial perspective view of the same.

FIG. 4 is a plan view showing another example of the shaft coupling.

FIG. 5 is a sectional perspective view showing a conventional spent fuel storage facility.

[Explanation of symbols]

 1 pit 1a pit side wall 2 rack cell 2a insertion port 3 rack support plate 3a rack support plate outer peripheral edge portion 4 cutout portion 5,6 joint member 5a, 6a hawk portion 5b, 6b arm portion G gap S strut

Claims (2)

[Claims] 1. A pit for storing cooling water, a large number of rack cells arranged substantially vertically in the pit for containing spent nuclear fuel, and a plurality of substantially horizontal rack support plates for connecting and supporting the rack cells. In the storage facility for spent nuclear fuel, the rack support plate is formed with a gap having a width that allows thermal expansion of the rack support plate between the outer peripheral edge of the rack support plate and the side wall of the pit. A plurality of notches are formed in the outer peripheral portion of the rack, and a joint member for connecting the rack support plate to the pit side wall movably in the vertical and horizontal directions is provided in the notches. Storage facility for nuclear fuel. 2. The spent nuclear fuel storage facility according to claim 1, wherein the joint member uses a ball coupling.