JP2010014681A - Spent fuel storage rack and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the boron concentration, to prevent reduction in toughness of material, even if the boron concentration is increased, and to keep high strength with respect to excessive seismic force. <P>SOLUTION: This spent fuel storage rack 1 stores and holds a prism spent fuel in many cells 3 formed in a lattice shape. A flat plate made of stainless steel is assembled into a double-lattice shape, and a boron stainless plate 12 of high boron concentration exceeding 1% is stuck to the inner part of each lattice. The flat plate made of stainless steel is assembled into a double-lattice shape, and the boron stainless plate of high boron concentration exceeding 1% is stuck to the inner part of each lattice. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spent fuel storage rack that accommodates and stores spent fuel taken out from a nuclear reactor in a fuel storage pool and a method for manufacturing the same. In particular, the invention is highly subcritical and can ensure safety, and can be easily processed. It can be related to technology.

  Generally, in a nuclear power plant, after a nuclear reactor is operated for a certain period, it is accommodated in a spent fuel storage rack installed in the spent fuel storage pool before the spent fuel taken out from the core is reprocessed. It is stored and cooled and the decay heat of the fuel is removed.

  As a material for such a spent fuel storage rack, boron-added stainless steel containing boron having excellent neutron absorption capability is adopted, and the fuel storage rack is used to accommodate a rectangular fuel having a quadrangular prism shape. Also, a rectangular tube structure was generally used (see, for example, Patent Document 1).

In addition, conventionally, a prismatic-shaped spent fuel storage cell is made up of a boron-added stainless steel flat plate having a plurality of cell widths and a plurality of cell widths, and a comb-like protrusion inserted into the flat plate slit. And a boron-added stainless steel flat plate having a width corresponding to one cell, and a protrusion protruding from the flat plate slit inserted into the slit of the flat plate, and a protrusion protruding from the flat plate slit and the flat plate Has been disclosed (see, for example, Patent Document 2).
JP 2000-56060 A Japanese Patent No. 2939459

  The lattice structure and arrangement of spent fuel storage racks are determined from the viewpoint of ensuring subcriticality. Conventionally, square tubes made of boron-added stainless steel are arranged adjacent to each other in a lattice shape, and the square tubes are kept at regular intervals. Thus, the structure was positioned with a grid-like frame plate.

  In such a conventionally adopted structure, the boron concentration of the square tube is contained in the range of 0.7 to 1%. However, in terms of safety with respect to the storage of spent fuel with high subcriticality, boron is further added. There is a demand to increase the concentration. That is, in the prior art, the boron concentration of the square tube is up to about 1% (for example, about 0.75%), but it is desired to further increase the boron concentration.

  Further, in the case of a material containing boron, when the boron concentration is increased, the toughness is lowered and the material becomes brittle, and it has been difficult to adopt when an excessive seismic force is applied.

  Furthermore, bending or welding may be prohibited for high-concentration boron stainless steel sheets.

  The present invention has been made in view of such circumstances, has high subcriticality, can ensure safety, and is processed in comparison with the one using an absorbent material inside a stainless steel square tube. Use that can be simplified, and that the pitch accuracy between fuel storage cells can be kept good by combining and combining plate-like lattice plates with protrusions and slits, and that the assembly can be easily performed and the density can be increased. An object of the present invention is to provide a spent fuel storage rack and a method for manufacturing the same.

  In order to achieve the above object, according to the present invention, there is provided a spent fuel storage rack for storing and storing prismatic spent fuel in a number of cells formed in a lattice. Provided is a spent fuel storage rack which is assembled in a lattice shape and has a structure in which a boron stainless steel plate having a high boron concentration exceeding 1% is attached to an inner surface portion of each lattice.

  In the present invention, a plurality of column units are individually manufactured for each column, the column units are stacked, and the outer surface is fixed with a plate or a beam. Forming a double lattice structure, forming a certain gap between the row units so that a water space is formed between the row units, and fixing the outer surface with a plate or a beam, and the inner surface of each cell A step of affixing a boron-added stainless steel plate and a step of forming a water space of a constant interval between each cell, and making the strength member a stainless plate forming a double lattice and an outer plate or beam A method for manufacturing a spent fuel storage rack is provided.

  According to the present invention, it is possible to increase the boron concentration by assembling a flat plate made of stainless steel into a double lattice shape and attaching a boron stainless plate having a high boron concentration exceeding 1% to the inner surface portion of each lattice, Even if the boron concentration is increased, the toughness of the material does not decrease, and high strength can be maintained against excessive seismic force. That is, in the present invention, it is a boron stainless steel plate and does not require processing that causes toughness such as bending and welding. Further, the strength member is a stainless steel plate portion, and the boron-added stainless steel plate does not need to be configured to handle the seismic load.

  Hereinafter, embodiments of a spent fuel storage rack and a method for manufacturing the same according to the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing the entire configuration of the spent fuel storage rack with a part cut away, and FIG. 2 is a plan view of FIG.

  As shown in FIGS. 1 and 2, the spent fuel storage rack 1 of the present embodiment has a vertically long rectangular columnar box shape as a whole, and a plurality of stainless steel vertically long flat plates 2 are opposed to each other. A plurality of cells 3 for storing spent fuel storage racks are formed by crossing and assembling the side edge portions of the flat plates 2. That is, in the spent fuel storage rack 1 of the present embodiment, a plurality of stainless steel flat plates 2 are opposed to each other, and spacers 4 are interposed between the opposed portions to form gaps 5 having a predetermined interval. Each gap | interval 5 part is comprised as water space. Further, the outer peripheral side of the spent fuel storage rack 1 is fastened by a restraining member 6 having a predetermined vertical width.

  3 is a side view illustrating two unit units of the spent fuel storage rack 1 shown in FIG. 1 in a separated state, and FIG. 4 is a plan view of FIG.

  As shown in FIGS. 3 and 4, the spent fuel storage rack 1 is composed of a plurality of unit units 1a. This unit unit 1a is a vertically long thin plate composed of a pair of wide side plates 7 and 7 that face each other and a pair of end plates 8 and 8 that close the ends on the long sides of the side plates 7 and 7. The spacer 4 has a box shape, and the above-described spacer 4 protrudes vertically at a predetermined interval.

  In addition, as shown in FIG. 4, a plurality of partition plates 9 are provided in the thin box to configure each cell 3 with a certain interval in the length direction. These partition plates 9 are configured as a pair of one pair facing each other with a certain interval narrower than the width of the cell 3, whereby the unit units 1 a are assembled in a double lattice shape to form a steel plate. In addition to the strength structure, a water gap is formed between a pair of adjacent partition plates 9.

  In this way, the lattice between each pair of partition plates 9 and 9 is a row unit that stores a plurality of spent fuels in a single row, and a water space 10 is formed between each cell 3 by the partition plates 9 and 9. In addition, each unit can be arranged adjacent to each other in a plurality of rows.

  FIG. 5 is an enlarged perspective view showing a configuration in which a plurality of unit units 1 a are assembled and assembled to form a spent fuel storage rack 1.

  As shown in FIG. 5, in the spent fuel storage rack 1 of the present embodiment, the whole unit unit 1a is configured by connecting a plurality of the unit units 1a in such a manner that the side plates 7 face each other.

  That is, the spent fuel storage rack 1 has a vertically long rectangular columnar box shape as a whole, and a plurality of stainless steel vertical plates 2 face each other in the lateral direction. Further, the side edge portions of each flat plate 2 are assembled so as to intersect with each other to form a large number of cells 3 for storing spent fuel storage racks. A boron-added stainless steel neutron absorbing plate, which will be described later, is attached to the inner surface side of the cell.

  A plurality of stainless steel flat plates 2 are opposed to each other, spacers 4 are interposed between the opposed portions to form gaps 5 having a constant interval, and these gaps 5 are configured as water spaces. The Further, the outer peripheral side of the spent fuel storage rack 1 is fastened by a restraining member 6 having a predetermined length in the vertical direction.

  Further, the unit unit 1a constituting the spent fuel storage rack 1 includes a pair of wide side plates 7 and 7 facing each other and a pair of the side plates 7 and 7 closing each end on the long side. The end plates 8 and 8 form a vertically long thin box shape, and the spacer 4 is projected on the outer vertical surface at a predetermined interval in the vertical direction. A plurality of partition plates 9 for partitioning and configuring each cell 3 are provided at a certain interval, and the partition plate 9 is spaced apart by a certain interval narrower than the width of the cell 3 and one pair of one pair facing each other. The unit unit 1a is assembled in a double lattice shape.

  Next, the assembly configuration, material, and manufacturing method of the above-described spent fuel storage rack 1 will be described with reference to FIGS.

  FIG. 6 is a plan view for explaining an example of the assembly configuration and manufacturing method of the spent fuel storage rack 1, and shows a part of FIG. 4 in an enlarged manner.

  The spent fuel storage rack 1 shown in FIG. 6 is constructed by assembling stainless steel flat plates (side plates 7, end plates 8 and partition plates 9 and 9) into a double lattice shape, and the inner surface (4 A boron stainless plate 12 having a high boron concentration exceeding 1% is attached to the entire surface. In this embodiment, the width of the boron stainless steel plate 12 having a high boron concentration is set to a width over the entire lateral width of the inner surface of the cell 3. Fuel 14 is stored on the inner surface side of the cell 3.

  In this case, of the plates constituting the lattice, the end portions of the end plate 8 and the partition plates 9 and 9 are fitted into the side plate 7 in a comb shape, and the end portions of the end plate 8 and the partition plates 9 and 9 are the side plates. The protruding portions 9 a and 9 a and the side plate 7 are connected by the welded portion 13.

  With this configuration, the pitch accuracy between the fuel storage cells can be kept good, the assembly is easy, and the density can be increased.

  7 to 10 specifically show a structure in which the end portions of the end plate 8 and the partition plates 9 and 9 are fitted into the side plate 7 in a comb shape.

  In FIG. 7, through-holes 15 are formed in a pair of side plates 7, 7 that face each other, and the protrusions 16 of the side plates 7 are inserted into these through-holes 15, so The end is fitted into the side plate 7 in a comb shape and fixed by welding.

  That is, the end portion of the side plate 7 constituting the lattice has a comb-like fitting structure, the tip portion of the comb shape protrudes from the outer surface of the side plate 7, and the protruding portion and the flat plate are connected by welding. With this configuration, the end portion of the boron-added stainless steel plate on the inner surface of the cell has a comb-shaped assembly structure and is formed into a box shape with four plates.

  FIG. 8 shows a configuration in which through holes 15 are formed in a pair of side plates 7 and 7 facing each other, and protrusions 16 of the side plates 7 are inserted through these through holes 15.

  With this configuration, the end portions of the end plate 8 and the partition plates 9 and 9 are inserted into the side plate 7 in a comb shape and penetrated, and the protruding portion of the protruding portion 16 is welded, thereby further strengthening the structure. be able to.

  As described above, in the present embodiment, the end of the side plate 2 constituting the lattice has a comb-type fitting structure, and the comb-shaped tip portion protrudes from the outer surface of the side plate 7, and the protruding portion and the side plate 2 that is a flat plate are connected to each other. It is configured to be connected by welding. With this configuration, the end of the boron-added stainless steel plate 12 on the inner surface of the cell 3 can be a comb-shaped assembly structure, and a box-shaped configuration can be formed with four plates.

  FIG. 9 is a perspective view showing a configuration in which the boron-added stainless steel plate 12 is attached to the inside of the flat plate 2 that is a stainless steel plate on the lattice structure side, and FIG. 10 is a longitudinal sectional view taken along line AA in FIG.

  As shown in these drawings, in a comb structure in which a boron-added stainless steel plate 12 is attached to the inside of a stainless steel plate 2 on the lattice structure side, protrusions 2b and 12b are formed on both the boron-added stainless steel plate 12 and the side plate 2 made of stainless steel plate. The projections 2b and 12b are inserted into the holes 20 of the side plate 8 and welded by the welded portion 21.

  According to this configuration, the boron-added stainless steel plate 12 having brittleness can be integrally formed and strengthened with the side plate 2 made of stainless steel, and even when it is inserted into the side plate 7 to form a comb-shaped assembly structure made of stainless steel plates. A sufficient strength against the load can be obtained.

  FIGS. 11-13 has shown the structure which fixes the boron addition stainless steel plate 12 of the cell 3 inner surface with the volt | bolt, nut, etc. which are fastening members instead of welding.

  FIG. 11 is a plan view showing the spent fuel storage rack 1, and FIG. 12 is an enlarged view showing a bolt fastening portion which is a part of FIG. 13 and 14 are plan views showing modifications of FIG.

  As shown in FIGS. 11 and 12, in this example, in the structure in which the four corners of the inner surface of the cell 3 are welded from the inside, both ends of the comb-shaped boron-added stainless steel plate 12 corresponding to the welded portion are notched, By widening the space area of the corner, it is possible to easily access a welding apparatus used during welding.

  11 and 12, the width of the boron-added stainless steel plate 12 is substantially the same as the width of the fuel 14 and is narrower than the width of the inner surface of the cell 3. Further, the boron-added stainless steel plate 12 on the inner surface of the cell 3 is fixed with a fastening member including a bolt 18 and a nut 19.

  With this configuration, the boron-added stainless steel plate 12 on the inner surface of the cell 3 is fixed with a fastening member, and the use of the comb shape due to the unevenness can be omitted. With this configuration, the welding apparatus can be easily accessed with a simple configuration.

  Further, in the modification shown in FIG. 13, the width of the boron-added stainless steel plate 12 is made substantially equal to or greater than the width of the fuel 14, and the boron-added stainless steel plate 12 on the inner surface of the cell 3 is a fastening member made up of a bolt 18 and a nut 19. The configuration is fixed.

  According to this configuration, the neutron absorption function can be enhanced by making the width of the boron-added stainless steel plate 12 substantially equal to or greater than the width of the fuel 14.

  Further, in the modification shown in FIG. 14, the side plate 7 and the end plate constituting the cell 3 are the same as the configuration of FIG. 13 in that the width of the boron-added stainless steel plate 12 is approximately equal to or greater than the width of the fuel 14. 8. It is set as the structure which adhere | attaches the boron addition stainless steel plate 12 to the inner surface of the partition plate 9, and it is set as the structure which can omit fastening members, such as a bolt and a nut.

  15 and 16 show a configuration in which the outer corner of the boron-added stainless steel plate 12 is welded. 15 is a perspective view showing a corner portion of the rack outer surface, and FIG. 16 is an enlarged view showing a part of FIG.

  In the example of FIGS. 15 and 16, as indicated by the phantom line, a notch 22 is formed at the outer corner of the boron-added stainless steel plate 12 and this portion is welded. This makes it possible to increase the bonding strength of the assembled portion by welding the notch portion 22 and to increase the structural strength of the entire rack as compared with the case where the bonding is simply performed by assembly. can do.

  When manufacturing a spent fuel storage rack having the above configuration, first, a plurality of column units are manufactured individually for each column.

  Next, each row unit is stacked and the outer surface is fixed with a plate or a beam. Thereafter, the column unit forms a water space between lattices in the column direction to form a double lattice structure. Then, the outer surface is fixed with a plate or a beam with a certain gap between the row units so that a water space is formed between the row units.

  Further, a boron-added stainless steel plate is attached to the inner surface of each cell. Thereafter, water spaces with a constant interval are formed between the cells. The strength member is a boron-added stainless steel plate forming a double lattice and an outer plate or beam. By sequentially performing the above steps, the spent fuel storage rack can be efficiently manufactured.

  As described above, according to the present embodiment, it is a boron stainless steel plate and does not require processing that causes toughness such as bending and welding, and the strength member is a stainless steel plate portion, and boron is added. Stainless steel plates do not need to be configured to handle seismic loads, and can increase the boron concentration. Even if the boron concentration is increased, the toughness of the material does not decrease, and high strength is maintained against excessive seismic forces. can do. A spent fuel storage rack can be efficiently manufactured.

1 is an overall configuration diagram showing a rack structure according to an embodiment of the present invention. The top view of FIG. The side view which illustrates the unit unit of the spent fuel storage rack 1 shown in FIG. FIG. 4 is a plan view of FIG. 3. FIG. 2 is an enlarged perspective view showing a configuration in which a plurality of unit units according to an embodiment of the present invention are assembled and assembled to form a rack. The lattice plate assembly explanatory drawing by one Embodiment of this invention. The rack unit principal part expansion perspective view by one Embodiment of this invention. The principal part expansion perspective view which shows the modification of a rack unit. The perspective view which shows the structure which affixed the boron addition stainless steel plate on the inner side of the flat plate which is a stainless steel plate of the lattice structure side. FIG. 10 is a longitudinal sectional view taken along line AA in FIG. 9. The top view which shows a spent fuel storage rack. The enlarged view which shows the bolt fastening part which is a part of FIG. The top view which shows the modification of FIG. The top view which shows the modification of FIG. The perspective view which shows a rack outer surface corner | angular part. The enlarged view which shows a part of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... spent fuel storage rack, 1a unit unit, 2 flat plate, 3 cell, 4 spacer, 5 gap, 6 restraining member, 7 side plate, 8 end plate, 9 partition plate, 10 Water space, 12 ... Boron stainless steel plate with high boron concentration, 13 ... weld, 14 ... fuel, 15 ... hole, 16 ... projection, 17 ... weld, 18 ... bolt, 19 ... nut.

Claims (10)

A spent fuel storage rack for storing and storing prismatic spent fuel in a large number of cells formed in a grid. A stainless steel flat plate is assembled in a double grid and 1 is attached to the inner surface of each grid. A spent fuel storage rack characterized by a structure in which a boron stainless steel plate having a high boron concentration exceeding 50% is attached. The lattice assembled in a double lattice shape is a row unit that stores a plurality of spent fuels in a single row, a water space is formed between each cell, and each unit can be placed adjacent in multiple rows. The spent fuel storage rack according to claim 1. The spent fuel storage rack according to claim 2, wherein a spacer is provided between the row units so as to keep a mutual gap constant. The spent fuel storage rack according to claim 2, wherein the four corners of the inner surface of the cell are joined from the inside by welding. The spent fuel storage rack according to claim 2, wherein the ends of the plates constituting the lattice have a comb-like fitting structure, the tip ends of the comb shape protrude from the outer surface of the plates, and the protruding portions and the plates are connected by welding. . The spent fuel storage rack according to any one of claims 1 to 3, wherein an end of the boron-added stainless steel plate on the inner surface of the cell has a comb-shaped assembly structure and is formed into a box shape with four plates. The spent fuel storage rack according to claim 4 or 6, wherein, in a structure in which the four corners of the inner surface of the cell are welded from the inside, the comb-shaped end corresponding to the welded portion is cut out to allow access to the welding device. . The spent fuel storage rack according to any one of claims 1 to 3, wherein the boron-added stainless steel plate on the inner surface of the cell is fixed with a fastening member. 5. The spent fuel according to claim 4, wherein in the structure in which the four inner corners of the cell are welded from the inside, the end of the boron-added stainless steel plate corresponding to the welded portion is cut away to reduce the plate width, thereby enabling access to the welding apparatus. Storage rack. A plurality of row units are individually produced for each row, the row units are stacked, the outer surface is fixed with a plate or a beam, and the row unit is doubled by forming a water space between lattices in the row direction. A process of making a lattice structure, a process of fixing the outer surface with a plate or a beam with a certain gap between the row units so that a water space is formed between the row units, and a boron-added stainless steel plate on the inner surface of each cell A spent fuel comprising a step of attaching and a step of forming water spaces at regular intervals between each cell, wherein the strength member is a stainless steel plate forming a double lattice and an outer plate or beam. Storage rack manufacturing method.

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