JP3080954B1 - Spent fuel storage rack - Google Patents

Abstract

An object of the present invention is to provide a spent fuel storage rack having a high neutron absorption capacity by greatly reducing a manufacturing time by eliminating a welded portion of a strip-shaped frame plate as a constituent element. A rectangular parallelepiped spent fuel storage rack (1) is installed in a fuel storage pool of a nuclear facility and has lattice cells (3) for separately storing a plurality of fuel assemblies (2) in a matrix arrangement of a plurality of rows and a plurality of columns. In the above, the lattice-shaped cell has an outer frame plate 16 arranged on the outermost periphery of the rack, a lateral width substantially corresponding to the integral width of the fuel assembly, and a length substantially equivalent to the effective length of the fuel assembly. A plurality of strip-shaped frame plates 5 arranged so as to divide a space surrounded by the plates into a plurality of rows and a plurality of columns.
And a support 15 for fitting and holding the strip frame plates together or the strip frame plate and the outer frame plate, and supports the horizontal load of the fuel assembly on the fuel storage cell 13. In addition to providing a grid plate, a base plate 17 for supporting a vertical load of the fuel assembly is provided below the fuel storage cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention is installed in a fuel storage pool of a nuclear facility such as a nuclear power plant or a reprocessing facility,
The present invention relates to an improved spent fuel storage rack having a lattice structure for storing and storing spent fuel assemblies taken out of a nuclear reactor.

[0002]

2. Description of the Related Art Generally, in a nuclear power plant,
A spent fuel storage rack installed in the fuel storage pool stores spent fuel removed from the core after a certain period of operation of the reactor until reprocessing.

A conventional example of a spent fuel storage rack used in such a case will be described with reference to FIGS.
FIG. 13 is a plan view of the entire spent fuel storage rack, and FIG. 14 is an exploded perspective view showing rack components in FIG. 15 is an enlarged sectional view taken along the line AA of FIG. 13, and FIGS. 16 and 17 are sectional views taken along the line BB and CC of FIG. 15, respectively.

As shown in FIG. 13, the spent fuel storage rack 1 has a rectangular parallelepiped structure having lattice cells 3 for storing a plurality of fuel assemblies 2 in a matrix arrangement of a plurality of rows and a plurality of columns. Have been. The lattice cells 3 are arranged in a row direction (for example, the direction a in FIG. 13) and a column direction (for example, b in FIG. 13).
Direction), a plurality of flat lattice plates 4 made of a vertical plate material having a width corresponding to the width W when all the fuel assemblies 2 are arranged in one direction, and the width w of the integrated fuel assembly 2 It is constituted by a combination with a plurality of strip-shaped lattice plates 5 made of a plate material having a width which is different from that of the first embodiment.

[0005] Each of the strip-shaped lattice plates 5 is shown in Figs.
As shown in the figure, the thickness t of the flat lattice plate 4
It has a plurality of protrusions 6 whose protrusion length is longer than the protrusion length, and a recess 7 into which the protrusion 6 of another strip-shaped lattice plate 5 can be fitted at a position corresponding to the protrusion 6 on the other end side in the width direction. On the other hand, the flat lattice plate 4 is provided with a plurality of slits 8 into which the projections 6 of the rectangular lattice plate 5 can be inserted.

As shown in FIGS. 16 and 17, one edge of the strip-shaped grid plate 5 is brought into contact with one side surface of the flat-shaped grid plate 4 in an orthogonal state, and the strip-shaped grid plate 5
Is inserted into the slit 8 of the flat lattice plate 4 to form a penetrating state.

On the other hand, the other end of another strip-shaped grid plate 4 is made to abut on the other side surface of the flat-plate grid plate 4 in an orthogonal state, and a projection penetrating through the recess 7 of this another strip-shaped grid plate 4 is provided. 6 are fitted together.

[0008] The strip-shaped grid plate 5 and the flat grid plate 4 combined in this way are integrated by a weld 9 at a corner position where they come into contact with each other. The rack 1 is configured.

The spent fuel storage rack 1 is mounted on a base 10 provided on the bottom of the spent fuel storage pool.
The lower end of the fuel assembly 2 accommodated in the spent fuel storage rack 1 is fixed by bolts and nuts (not shown) or the like, and is fitted and supported by seat holes (not shown) formed on the base 10.

In recent years, there has been a demand for increasing the storage capacity in order to effectively use the space in the spent fuel storage pool. In order to respond to this, a material with a large neutron absorption capacity is interposed between the stored fuels, and the storage intervals of the stored fuels are reduced while maintaining the subcriticality of the fuels,
A spent fuel storage rack has been proposed in which the interposed member is also used as a strength member for supporting stored fuel during an earthquake or the like, thereby increasing the density of fuel storage.

Conventionally, such a constituent material is made of boron-added stainless steel having excellent neutron absorption capacity and good structural strength, and the whole spent fuel storage rack, that is, the flat lattice plate and all A configuration applied to a strip-shaped lattice plate has been developed.

[0012]

However, in the conventional spent fuel storage rack 1 described above, the protrusions 6 of the strip-shaped grid plate 5 are formed by the slits 8 from one side of the flat grid plate 4.
And the recesses 7 of another strip-shaped lattice plate 5 are fitted into the protrusions 6 penetrating the other side surface, and the corner positions of the assembly are integrated by welding. In addition, since welding work is performed between narrow grids, it is necessary to use a special jig and tool, and there is a problem in economy.

Conventionally, all the materials of the flat grid plate 4 and the rectangular grid plate 5 are made of boron-added stainless steel. However, such materials are difficult to weld as the boron content increases. have. For this reason, boron having excellent neutron absorption ability can be added only to a certain amount, and it has been difficult to sufficiently utilize boron-added stainless steel as a neutron absorber.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the production time is greatly reduced by eliminating the welding portion of the strip-shaped frame plate which is a constituent element, and the spent fuel storage having a high neutron absorption capacity is provided. To provide a rack.

[0015]

In order to achieve the above object, according to the present invention, a plurality of fuel assemblies are installed in a nuclear fuel storage pool and divided into a plurality of rows and a plurality of columns in a matrix. In a rectangular parallelepiped spent fuel storage rack having lattice cells to be stored, the lattice cells have an outer frame plate arranged on the outermost periphery of the rack, and a lateral width substantially corresponding to an integral width of the fuel assembly and its width. A plurality of strip frame plates having a length substantially corresponding to the effective length of the fuel assembly and arranged to divide a space surrounded by the outer frame plate into a plurality of rows and a plurality of columns; And a means for fitting and holding an outer strip-shaped frame plate to the outer frame plate, and supports a horizontal load of the fuel assembly above the fuel storage cell. A grid plate is provided and the fuel storage At the bottom of, providing a spent fuel storage rack, characterized in that a base plate for supporting a vertical load of the fuel assembly.

According to a second aspect of the present invention, in the spent fuel storage rack according to the first aspect, the strip-shaped frame plate has a projection at a lower end, and the projection is fitted into a groove provided on the base plate. A spent fuel storage rack, characterized in that it is positioned by

According to a third aspect of the present invention, in the spent fuel storage rack according to the first aspect, the grid plate includes a plurality of upper elements and lower elements that are combined with each other in a grid pattern through slits, and the upper element Is a lower opening slit formed at intervals along the longitudinal direction of the element, and the slit of the lower element is an upper opening slit formed at intervals along the longitudinal direction of the element. A spent fuel storage rack is provided.

According to a fourth aspect of the present invention, in the spent fuel storage rack according to the first aspect, the strip-shaped frame plate is formed of one rectangular plate material or a fuel assembly along the length direction of the fuel assembly. Provided is a spent fuel storage rack comprising a plurality of divided plate members stacked along a length direction.

According to a fifth aspect of the present invention, there is provided the spent fuel storage rack according to the first aspect, wherein the bottom of the support is fitted or screwed to the base plate. .

According to a sixth aspect of the present invention, there is provided the spent fuel storage rack according to the first aspect, wherein the lattice plate is fitted or screwed to the upper end of the support. .

According to a seventh aspect of the present invention, in the spent fuel storage rack according to the first aspect, at least one of a groove, a hole, and a projection is formed at an upper end of the support or at an intersection of a grid plate disposed thereon. The spent fuel storage rack is characterized in that the support and the lattice plate are connected by fitting them.

According to the eighth aspect of the present invention, a rectangular parallelepiped spent fuel storage rack is provided in a nuclear fuel storage pool and has lattice cells for storing a plurality of fuel assemblies in a matrix arrangement of a plurality of rows and a plurality of columns. In the grid-like cell,
An outer frame plate arranged at the outermost periphery of the rack, and a space surrounded by the outer frame plate having a width substantially equivalent to an integral width of the fuel assembly and a length substantially equivalent to an effective length of the fuel assembly. A plurality of strip-shaped frame plates arranged to be divided into a plurality of rows and a plurality of columns, a holding member for fitting and holding these strip-shaped frame plates, and an outer strip-shaped frame plate fitted to the outer frame plate A spent fuel storage rack formed by a holding member for holding and connecting the rectangular frame plate by fitting into a slit provided in the rectangular frame plate.

According to a ninth aspect of the present invention, in the spent fuel storage rack according to any one of the first to eighth aspects, the strip-shaped frame plate is made of a material having a high neutron absorption capacity, and the outer frame, the support, The grid plate, the base plate, or the holding member is provided with a spent fuel storage rack, characterized in that the grid plate, the base plate, or the holding member is made of a material having a lower neutron absorption capacity than the material of the strip-shaped frame plate.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a spent fuel storage rack according to the present invention will be described with reference to FIGS.

FIGS. 1 to 7 show a first embodiment of the present invention. FIG. 1 is a plan view of a spent fuel storage rack,
FIG. 2 is an enlarged sectional view taken along line DD of FIG. FIG. 3 is a sectional view taken along line EE of FIG. 2, and FIGS.
It is an enlarged view of the F section and the G section. FIG. 6 is an exploded perspective view showing a lower configuration of the spent fuel storage rack, and FIG. 7 is an exploded perspective view showing the same upper configuration.

As shown in these figures, the spent fuel storage rack 11 of the present embodiment includes a grid-like fuel storage cell 13 for storing a plurality of fuel assemblies 12 in a matrix arrangement of a plurality of rows and a plurality of columns. It has a rectangular parallelepiped configuration.
The fuel storage cell 13 is defined by a plurality of strip-shaped frame plates 14, support columns 15 for fitting and holding these, and an outer frame plate 16 serving as an outer peripheral wall of the rack. The lower end of the fuel assembly 12 housed in the spent fuel storage rack 11 is supported by a base plate 17 described later. The spent fuel storage rack 11 is fixed on a base (not shown) provided on the bottom surface of the spent fuel storage pool with bolts and nuts.

Each of the strip frame plates 14 has a vertically long rectangular shape having a width substantially corresponding to the width of one side of one fuel assembly 12 and a length substantially corresponding to the effective length of the fuel assembly 12. It is an integral structure. The support 15 is a strip frame 1
4, and has a strip-shaped frame plate 1 on its outer surface.
A vertically elongated groove 1 for fitting and holding an end face along the longitudinal direction of No. 4
8 is provided. In this embodiment, two types of columns 15 are provided: a column 15a for rack outer peripheral portion disposed along the inner surface of the outer frame plate 16, and a column 15b for rack inner peripheral portion disposed inside thereof. ing.

As shown in FIGS. 3 and 5, the rack outer peripheral portion supporting column 15a has a single groove 18 and is fixedly arranged at intervals on the inner surface of the outer frame plate 16, and one groove 18 is provided in the groove 18. Is fitted and held. As shown in FIGS. 3 and 4, the rack inner peripheral portion arrangement support column 15b has four grooves 18 on the outer peripheral surface at 90-degree intervals.
8, a total of four strip-shaped frame plates 14 are fitted and held. In addition, the width of each groove 18 is substantially the same as the thickness of the strip-shaped frame plate 14, so that each strip-shaped frame plate 14 can be securely held.

The fuel storage cells having the strip-shaped frame plates 14 on all sides are formed by fitting and holding the respective side ends of the plurality of strip-shaped frame plates 14 arranged vertically and horizontally in the grooves 18 of the columns 15a and 15b. 13 are formed, and the adjacent fuel storage cells 13 are connected by columns 15.

The lower end of the strip-shaped frame plate 14 is
As shown in FIG. 5, a tongue-shaped projection 19 is formed, and a groove 26 provided in a base plate 17 disposed at the bottom of the rack is formed in a groove 26.
By fitting these projections 19, the strip-shaped frame 1
4 are positioned and connected to the base plate 17. Further, a pin-shaped projection 21 is provided at the lower end of the column 15 so as to project therefrom. The length of the projection 21 is larger than the thickness of the base plate 17, is fitted and inserted into a through hole 27 provided in the base plate 17 from the upper surface side, and penetrates the lower surface side.
The base plate 17 and the support 15 are connected and fixed by welding the through end of the protrusion 21 of the support 15 to the lower surface of the base plate 17.

On the other hand, a grid plate 25 for supporting the horizontal load of the fuel assembly is provided on the upper part of the fuel storage cell 13, as shown in FIG. The lattice plate 25 is composed of a plurality of upper elements 25a and lower elements 25b which are combined in a grid pattern with each other via slits 23 and 24, and the slits 23 of the upper element 25a are spaced along the longitudinal direction of the upper element 25a. The slit 24 of the lower element 25b is an upper opening slit formed at intervals along the longitudinal direction of the element 25b. In such a state that the lattice plates 25 are combined, the lattice plates 25 are arranged inside the upper end of the outer frame plate 16 and mounted on the support columns 15 and the upper ends of the strip-shaped frame plates 14 with their intersections coincident with each other. A grid having holes matching the fuel storage cells 13 is formed.

In such a configuration, the rectangular frame plate 14
Is made of a material having a high neutron absorption capacity, while the outer frame plate 16, the support 15, the grid plate 25, and the base plate 17 are made of a material having a lower neutron absorption capacity than the strip frame plate 14.

Specifically, boron-added stainless steel is used as the material of the strip-shaped frame plate 14.
6, ordinary stainless steel to which boron is not added is applied as a material of the support 15, the grid plate 25 and the base plate 17.

[0034] Both the boron-added stainless steel and the stainless steel not containing boron have a function of absorbing neutrons emitted from spent fuel. The boron-added stainless steel applied as the material of the strip-shaped frame plate 14 has a lower weldability as the amount of boron added increases, and thus is disposed only inside without welding and serves as a neutron absorber. .

For this reason, the conventional spent fuel storage rack 1
By applying a boron-added stainless steel having a larger amount of boron as compared to the boron-added stainless steel used in the above or to a material of the strip-shaped frame plate 14 in which the boron-added stainless steel is concentrated, to reduce the plate thickness. In addition, the spent fuel storage rack 11 having a higher density and a sufficient neutron absorption effect can be realized.

Further, by eliminating the welding of the boron-added stainless steel, difficult operations in manufacturing the spent fuel storage rack 11 are reduced, and the manufacturing cost is significantly reduced.

In this embodiment, the outer frame plate 16, the support 15, the grid plate 25, and the base plate 17 are made of
Although ordinary stainless steel to which boron is not added is applied, it may be made of boron-added stainless steel having a smaller amount of boron than the strip frame plate 14.

For example, in the future, it is conceivable that a higher fuel burnup will require a spent fuel storage rack 11 having even more excellent neutron absorption capability. In this case, it is necessary to utilize the neutron absorption effect of water. The column 15 can be hollow and the hollow can be filled with water. Alternatively, the neutron absorption ability can be increased by filling the hollow pillar 15 with boron-added stainless steel or concentrated boron-added stainless steel.

In this embodiment, the strip-shaped frame plate 14 is made of stainless steel containing boron or concentrated boron. However, the present invention is not limited to this, and other materials having an effect as a neutron absorbing material may be used. For example, hafnium, gadolinium, or the like can be used.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible. FIGS. 8 to 11 show modified examples as other embodiments. According to such a configuration, assembling and the like can be facilitated.

FIG. 8 shows a structure in which each strip-shaped frame plate 14 is divided. That is, in the above embodiment, the strip frame plate 14 having an integral structure having a length substantially corresponding to the effective length of the fuel assembly 12 is employed. As shown in FIG. 8, the fuel assembly 12 is made effective by being divided into a plurality of strip-shaped frame plates 14 each having a short length in the vertical direction and being fitted into the groove 18 of the support column 15 in a stacked state. The length can be substantially equivalent to the length.

FIG. 9 shows a modification of the connecting portion between the column 15 and the base plate 17. That is, a screw hole 22 a is formed at the lower end of the support 15, and the bolt 22 is connected to the screw hole 22 of the support 15 through a through hole 22 b formed in the base plate 17.
a, thereby positioning and fixing the column 15.

FIGS. 10 and 11 show a structure in which a grid plate 25 is connected to the upper end of the column 15. In the example shown in FIG. 10, a cross-shaped groove 28 is formed at the upper end of the column, and the intersection of the lattice plate 25 is fitted and inserted into this groove. Thereby, the support 15 and the grid plate 25 can be integrally fixed. In the example of FIG. 11, an opening is formed at the lower end of the intersection of the lattice plate 25, and a pin-shaped projection 30 projecting from the upper end of the support 15 is fitted and inserted. With such a configuration, the support 15
And the grid plate 25 can be integrally fixed.

FIG. 12 shows the support 15 in the above embodiment.
Instead of this, a strip-shaped frame plate 14 is provided, and a holding member for connecting and holding the strip-shaped frame plates 14 and the outer frame plate is provided. That is,
Slits 31 are provided at intervals in the vertical direction of the strip-shaped frame plate 14 and an outer frame plate (not shown) and at the same height position, and a disk or a polygonal plate as the holding member 32 is provided. Then, the holding members 31 may be fitted to the slits 30 provided in the strip-shaped frame plates 14 to connect the strip-shaped frame plates 14 to each other and to an outer frame plate (not shown).

According to the configuration of the above embodiment, the outer frame plate 1
6 and the grid plate 25 disposed above the fuel storage cell 13 sufficiently support the horizontal load of the fuel assembly 12, so that the strip frame plate 14 forming the fuel storage cell 13 is not welded and joined. It can be assembled, withstands vibrations at the time of an earthquake, etc., and can store a large number of fuel assemblies 12 safely and reliably.

Further, since the grid-like fuel storage cells 13 can be formed without welding work, the manufacture becomes easy.
The manufacturing cost of the spent fuel storage rack can be reduced.

Further, the neutron absorption capacity of the spent fuel storage rack can be increased by using a boron-added stainless steel or a concentrated boron-added stainless steel having a large amount of boron.

[0048]

As described above, according to the present invention, a grid-like fuel storage cell can be formed without welding work, which facilitates the manufacture and reduces the manufacturing cost of the spent fuel storage rack. Further, by using a boron-added stainless steel and a concentrated boron-added stainless steel having a large amount of boron, the neutron absorption capacity of the spent fuel storage rack can be enhanced.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line DD of FIG. 1;

FIG. 3 is a sectional view taken along line EE of FIG. 2;

FIG. 4 is an enlarged view of a portion F in FIG. 3;

FIG. 5 is an enlarged view of a portion G in FIG. 3;

FIG. 6 is an exploded perspective view of a lower portion of the spent fuel storage rack of the embodiment.

FIG. 7 is an exploded perspective view of the upper part of the spent fuel storage rack of the embodiment.

FIG. 8 is an exploded perspective view showing a strip frame plate according to another embodiment of the present invention.

FIG. 9 is an exploded perspective view showing a joint structure between a support and a base plate according to another embodiment of the present invention.

FIG. 10 is an exploded perspective view showing a joint structure between a support and a grid plate according to another embodiment of the present invention.

FIG. 11 is an exploded perspective view showing a joint structure between a support and a grid plate according to another embodiment of the present invention.

FIG. 12 is an exploded perspective view showing a column joint structure according to another embodiment of the present invention.

FIG. 13 is a plan view showing a conventional spent fuel storage rack.

FIG. 14 is an exploded perspective view for explaining a combination state of a strip grid plate and a flat grid plate in a conventional spent fuel storage rack.

FIG. 15 is an enlarged sectional view taken along line AA of FIG. 13;

FIG. 16 is a sectional view taken along line BB of FIG. 15;

FIG. 17 is a sectional view taken along line CC of FIG. 15;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spent fuel storage rack 2 Fuel assembly 3 Grid cell 4 Flat grid plate 5 Strip grid plate 6 Projection 7 Concave part 8 Slit 9 Welding part 10 Base 11 Spent fuel storage rack 12 Fuel assembly 13 Fuel storage cell 14 Strip Frame plate 15 Column 16 Outer frame plate 17 Base plate 18 Groove 19 Projection 21 Projection 22 Bolt 23 Slit 24 Disk 25 Grid plate 26 Groove 27 Through hole 28 Groove 29 Hole 30 Projection 22 Bolt 31 Slit 32 Holding member

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21C 19/07 G21C 19/40

Claims (9)

(57) [Claims] 1. A rectangular parallelepiped spent fuel storage rack, which is installed in a nuclear fuel storage pool and has lattice cells for separately storing a plurality of fuel assemblies in a matrix of a plurality of rows and a plurality of columns. The cell has an outer frame plate disposed on the outermost periphery of the rack, a width substantially corresponding to an integral width of the fuel assembly, and a length substantially corresponding to an effective length of the fuel assembly, and is surrounded by the outer frame plate. A plurality of strip-shaped frame plates arranged to divide the space to be divided into a plurality of rows and a plurality of columns, a support for fitting and holding these strip-shaped frame plates, and an outer strip-shaped frame plate on the outer frame plate. A lattice plate formed by the fitting and holding means and supporting the horizontal load of the fuel assembly is provided on the upper part of the fuel storage cell. The base plate to support the load Spent fuel storage rack according to claim. 2. The spent fuel storage rack according to claim 1, wherein the strip-shaped frame plate has a projection at a lower end, and is positioned by fitting the projection into a groove provided in the base plate. A spent fuel storage rack, characterized in that: 3. The spent fuel storage rack according to claim 1, wherein the lattice plate comprises a plurality of upper elements and lower elements which are combined with each other in a grid pattern through slits, and the slits of the upper element are the elements. A lower opening slit formed at intervals along the longitudinal direction of the element, and the slit of the lower element is an upper opening slit formed at intervals along the longitudinal direction of the element. Spent fuel storage rack. 4. The spent fuel storage rack according to claim 1, wherein the strip-shaped frame plate is a single rectangular plate material along the length direction of the fuel assembly or along the length direction of the fuel assembly. A spent fuel storage rack comprising a plurality of divided plate members stacked by stacking. 5. The spent fuel storage rack according to claim 1, wherein a bottom portion of the column is fitted or screwed to a base plate. 6. The spent fuel storage rack according to claim 1, wherein the lattice plate is fitted or screwed to an upper end of the column. 7. The spent fuel storage rack according to claim 1, wherein at least one of a groove, a hole, and a projection is formed at an upper end of the support or at an intersection of a lattice plate disposed thereon. The spent fuel storage rack, wherein the support and the lattice plate are connected to each other. 8. A rectangular parallelepiped spent fuel storage rack which is installed in a nuclear fuel storage pool and has lattice cells for storing a plurality of fuel assemblies in a matrix arrangement of a plurality of rows and a plurality of columns. The cell has an outer frame plate disposed on the outermost periphery of the rack, a width substantially corresponding to an integral width of the fuel assembly, and a length substantially corresponding to an effective length of the fuel assembly, and is surrounded by the outer frame plate. A plurality of strip-shaped frame plates arranged to divide the space to be divided into a plurality of rows and a plurality of columns, a holding member for fitting and holding these strip-shaped frame plates, and an outer strip-shaped A spent fuel storage rack formed by a holding member that fits and holds the rectangular frame plate, and is connected to the rectangular frame plate by fitting into a slit provided in the rectangular frame plate. 9. The spent fuel storage rack according to claim 1, wherein the strip frame plate is made of a material having a high neutron absorption capacity, and the outer frame, the support,
A spent fuel storage rack, wherein the lattice plate, the base plate, or the holding member is made of a material having a lower neutron absorption capacity than the material of the strip frame plate.