JP2012068203A - Seismic reinforcement structure and seismic reinforcement method of spent fuel storage rack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seismic reinforcement structure of a spent fuel storage rack which improves earthquake resistance of an existing spent fuel storage rack in a rectangular parallelepiped having a large aspect ratio.SOLUTION: A seismic reinforcement structure of a spent fuel storage rack seismically reinforces a spent fuel storage rack 1 having a rectangular parallelepiped shape where multiple cells, each of which stores one spent fuel assembly inside of the cell, are arranged in parallel, in a fuel storage pool 2. The seismic reinforcement structure of the spent fuel storage rack comprises: a reinforcement beam 14 fixed at the same height position as a holding part (a divider) 8 fastened in a short side direction of the spent fuel storage rack 1 in the fuel storage pool 2; additionally installed brackets 11 which are fixed to the reinforcement beam 14 and installed at both sides of the holding part 8 with a gap G2 in a short side direction of the spent fuel storage rack 1; and a gap adjustment mechanism 13 for adjusting the gap G2 between the holding part 8 and the additionally installed bracket 11 so that the gap becomes small by underwater remote operation.

Description

  The present invention relates to a seismic strengthening structure and a seismic strengthening method for a spent fuel storage rack that are intended to seismically strengthen a spent fuel storage rack that stores spent fuel generated in a nuclear power plant.

  In general, in nuclear power plants, spent fuel assemblies that have been removed from the reactor core after a certain period of operation have been stored in a spent fuel storage rack that has been installed in the fuel storage pool before reprocessing. It is stored and cooled to remove the decay heat of the spent fuel assembly.

  Known spent fuel storage racks have a rectangular parallelepiped shape in which a plurality of cells each containing spent fuel assemblies are arranged in parallel, and these spent fuel storage racks are located in the fuel storage pool. Multiple units are installed in

  Spent fuel storage racks are classified as the highest class in the earthquake resistance importance classification, and the fuel storage pool where the spent fuel storage racks are installed is located on the upper floor of the reactor building, so it is assumed in the event of an earthquake. It is known that the seismic intensity is high, and a spent fuel storage rack with improved seismic resistance has been proposed.

  Also, in recent years, there is a possibility that the seismic margin of existing spent fuel storage racks may be reduced due to a major review of the seismic standards, and there are plans to implement seismic reinforcement to improve seismic resistance. In particular, spent fuel storage racks installed in nuclear power plants introduced in the early stage have a structurally low seismic tolerance, and this measure is an urgent issue.

  As a structure for improving the earthquake resistance of the spent fuel storage rack, for example, there is a technique described in Patent Document 1. In this technology, a support for supporting the spent fuel storage rack is fixed to the spent fuel storage rack between the spent fuel storage racks and between the spent fuel storage rack and the fuel storage pool wall surface. Is.

JP-A-10-39087

  The existing spent fuel storage rack is fixed to the floor of the fuel storage pool with foundation bolts, and an existing horizontal beam is disposed at an intermediate position in the rack height direction. Both ends of the horizontal beam are supported on the pool side wall by bolts.

  Moreover, two brackets are fixed to the existing horizontal beam at a position corresponding to one side in the short side direction of one spent fuel storage rack. On the other hand, in the spent fuel storage rack, dividers are firmly attached to both sides in the short side direction, and the dividers are arranged between two brackets provided at positions corresponding to one side in the rack short side direction.

  Therefore, the divider suppresses a large fall in the short-side direction of the spent fuel storage rack by the bracket installed on the existing horizontal beam. Since there is a large gap in the rack short side direction between the divider and the bracket, the spent fuel storage rack basically has a self-supporting structure.

  Due to a recent review of earthquake resistance standards, in the spent fuel storage rack with a large aspect ratio of the rectangular parallelepiped in the short side direction (the short side direction and the long side direction in plan view, which means the aspect ratio), the short side direction When the foundation bolt is subjected to a tipping moment due to the shaking, a large stress is generated at the time of the earthquake, which may reduce the seismic tolerance. For this reason, in order to improve the earthquake resistance of such a spent fuel storage rack, it is desired to actively use an existing horizontal beam for reinforcement.

  In order to improve the seismic resistance of the spent fuel storage rack in this way, when reinforcing the structure of the rack itself, for example, by attaching a member for filling a gap in the short side direction between the divider and the existing bracket, In the case of supporting the short side direction, a tensile force is applied to the bolt of the existing horizontal beam due to the shaking in the short side direction. As a result, there is a problem that the seismic margin may be reduced by generating a large stress during an earthquake.

  Further, the member for filling the gap in the short side direction between the divider and the existing bracket has to be attached in water, and there is a problem that it is very difficult to adjust the gap to a minimum.

  The present invention has been made in consideration of the above-described circumstances, and improves the seismic resistance of an existing spent fuel storage rack having a large rectangular parallelepiped aspect ratio, and also improves on-site workability for improving the seismic resistance. An object of the present invention is to provide a seismic reinforcement structure and a seismic reinforcement method for a spent fuel storage rack capable of achieving the above.

  In order to achieve the above object, the seismic reinforcement structure for a spent fuel storage rack according to the present invention has a rectangular parallelepiped spent fuel in which a plurality of cells each containing spent fuel assemblies are arranged in parallel. A seismic reinforcement structure for a spent fuel storage rack that seismically reinforces the storage rack in the fuel storage pool, wherein the storage rack has a height equivalent to a holding portion fixed in the short side direction of the spent fuel storage rack in the fuel storage pool. A reinforcing beam fixed at a position, an additional bracket fixed to the reinforcing beam and installed on both sides of the holding portion with a gap in the short side direction of the spent fuel storage rack, the holding portion and the holding portion A gap adjusting mechanism that adjusts remotely underwater so that the gap between the additional bracket and the additional bracket is small.

  In addition, the method for seismic reinforcement of spent fuel storage racks according to the present invention includes a spent fuel storage rack having a rectangular parallelepiped shape in which a plurality of cells each containing spent fuel assemblies are arranged in parallel. A method for seismic reinforcement of a spent fuel storage rack that is seismically reinforced within the fuel storage pool, wherein a reinforcing beam is provided at a height equivalent to a holding portion fixed in the short side direction of the spent fuel storage rack in the fuel storage pool. A reinforcing beam fixing step for fixing, and after the reinforcing beam fixing step, an additional bracket is installed with a gap in the short side direction of the spent fuel storage rack fixed to the reinforcing beam and on both sides of the holding portion. After the installation bracket installation step and the additional bracket installation step, underwater remotely so that the gap between the holding portion and the additional bracket is reduced. And a gap adjusting step of adjusting the while adjusting mechanism, characterized in that it comprises a.

  According to the present invention, with respect to the short side direction seismic force of the spent fuel storage rack, the gap between the holding portion and the additional bracket is adjusted and held to a minimum by the gap adjusting mechanism. The seismic resistance of the existing spent fuel storage rack having a large ratio can be improved.

  Further, according to the present invention, it is possible to greatly improve the workability on site for improving the earthquake resistance by operating the gap adjusting mechanism remotely in water.

It is a vertical section lineblock diagram showing an earthquake-proof reinforcement structure of a spent fuel storage rack by a 1st embodiment of the present invention. It is a top view which shows the earthquake-proof reinforcement structure of FIG. FIG. 2 is a vertical sectional configuration diagram illustrating a gap adjustment mechanism of the seismic reinforcement structure of FIG. 1. It is a plane cross-section block diagram which shows the clearance gap adjustment mechanism of the earthquake-proof reinforcement structure of FIG. It is a vertical section lineblock diagram expanding and showing a crevice adjustment mechanism of a seismic reinforcement structure of a spent fuel storage rack by a 2nd embodiment of the present invention. It is a plane cross-section block diagram which shows the clearance gap adjustment mechanism of the earthquake-proof reinforcement structure of FIG. It is a longitudinal cross-section block diagram which shows the seismic reinforcement structure of the spent fuel storage rack by 3rd Embodiment of this invention.

  Embodiments of the seismic reinforcement structure for a spent fuel storage rack according to the present invention will be described below with reference to the drawings. In the following description, the description will be made based on the posture in which the bottom of the spent fuel storage rack is installed horizontally.

(First embodiment)
(Constitution)
FIG. 1 is a vertical sectional view showing a seismic reinforcement structure of a spent fuel storage rack according to a first embodiment of the present invention. FIG. 2 is a plan view showing the seismic reinforcement structure of FIG.

  In the present embodiment, a rectangular parallelepiped spent fuel storage rack in which a plurality of cells each containing spent fuel assemblies is arranged in parallel is seismically reinforced in the fuel storage pool.

  As shown in FIGS. 1 and 2, a plurality of existing spent fuel storage racks 1 are installed so as to be arranged in a lattice pattern on the floor 3 at the bottom in the fuel storage pool 2 in the reactor building. Yes. The fuel storage pool 2 is in a state where water is accommodated.

  The spent fuel storage rack 1 is vertically long as shown in FIG. 1 (FIG. 1 shows a narrow outer surface in the short side direction of the spent fuel storage rack 1). As shown in FIG. 2, it is formed in a rectangular tube shape having a rectangular shape in plan view. The short side surface and the long side surface of each spent fuel storage rack 1 are oriented in a certain direction so as to be orthogonal to each other, and there is a certain distance in the vertical and horizontal directions between the spent fuel storage racks 1. It is vacant.

  Each spent fuel storage rack 1 has an internal grid, and a cell for storing spent fuel assemblies one by one is formed by the internal grid. That is, a plurality of fuels are stored between the lattices in the rectangular parallelepiped spent fuel storage rack 1 arranged in parallel.

  As shown in FIG. 1, the spent fuel storage rack 1 is a self-supporting structure that is fixed to a floor surface 3 of a fuel storage pool 2 by foundation bolts 4. An existing horizontal beam 5 is installed at an intermediate position in the height direction of the spent fuel storage rack 1. Both ends of the horizontal beam 5 are supported on the pool side wall 6 via bolts 7.

  As shown in FIG. 2, dividers 8 as holding portions are firmly attached to both sides in the short side direction of the spent fuel storage rack 1, while one spent fuel is placed on the existing horizontal beam 5. Since two existing brackets 9 are installed on both sides of the divider 8 at positions corresponding to one side in the short side direction of the storage rack 1, the bracket 9 and the divider 8 are used between the brackets 9 and the divider 8. A gap G1 in the short side direction is provided for the purpose of suppressing a large collapse of the fuel storage rack 1 in the short side direction.

  Here, the divider 8 is firmly attached so as to protrude from both sides in the short side direction of the spent fuel storage rack 1, and is attached to the additional bracket 11 installed on the additional reinforcing beam 14 against shaking such as an earthquake. It is held and suppresses a large fall in the short side direction of the spent fuel storage rack 1.

  On the floor 3 of the fuel storage pool 2, reinforcing beam pedestals 15 are vertically provided on both sides, and the upper end of the reinforcing beam pedestal 15 extends to the lower surface of the existing horizontal beam 5. A support member 15 a is installed on the vertical extension line of the reinforcing beam receiving base 15 via the horizontal beam 5, and the supporting member 15 a supports the additional reinforcing beam 14. The reinforcing beam receiving base 15 may be formed long to the position where the additional reinforcing beam 14 is installed, and directly support the reinforcing beam 14.

  The additional reinforcing beam 14 is located on the upper stage of the horizontal beam 5, and the position in the vertical direction is set so that the divider 8 is disposed between the additional beam 14 and the horizontal beam 5. Between the reinforcing beam 14 and the side wall 6 of the fuel storage pool 2, a protruding member 16 formed in a wedge shape for adjusting the overall length of the reinforcing beam 14 is installed.

  The tension member 16 is not a single wedge as shown in FIG. 1, but a plurality of wedges are combined and tightened with bolts to cause displacement in the tension direction, and displacement is caused by a fluid such as air. Further, a jack-like member composed of a bolt and a link mechanism may be used.

  The reinforcing beam 14 is fixed to the lower surface of the reinforcing beam 14 and is disposed on both sides of the divider 8, and the gap adjustment for filling the gap G <b> 2 in the short side direction between the additional bracket 11 and the divider 8. A mechanism 13 is provided. Accordingly, the reinforcing beam 14 is installed on the upper stage of the existing horizontal beam 5 and is integrated with the reinforcing beam receiving base 15 installed on the floor surface 3 of the fuel storage pool 2. The reinforcing beam 14 may be held by a beam suspended from the upper end of the fuel storage pool 2 along the wall surface instead of the reinforcing beam receiving base 15.

  Next, the configuration of the gap adjusting mechanism 13 will be described based on FIGS. 3 and 4.

  FIG. 3 is a vertical cross-sectional configuration diagram showing the gap adjusting mechanism of the seismic reinforcement structure of FIG. FIG. 4 is a plane cross-sectional configuration diagram showing a gap adjusting mechanism of the seismic reinforcement structure of FIG.

  As shown in FIG. 3 and FIG. 4, the gap adjusting mechanism 13 includes a vertical rotation shaft 20 that can be rotated in a direction orthogonal to the longitudinal direction of the reinforcing beam 14, and a bevel gear fixed to the additional bracket 11. The box 19 can be rotated by rotation of a horizontal bolt 17 that is parallel to the longitudinal direction of the reinforcing beam 14 and is screwed into the additional bracket 11 and a bevel gear 19 that will be described later. 17 and a prismatic horizontal bar 18 which is inserted into the axis of 17.

  A female screw hole is formed in the lower portion of the additional bracket 11 in the horizontal direction. Since the horizontal bolt 17 is screwed into the female screw hole, a male screw is engraved on the outer peripheral surface of the horizontal bolt 17. A rectangular opening into which a prismatic horizontal bar 18 is inserted is formed at the axis of the horizontal bolt 17.

  The bevel gear box 19 has a vertical shaft 22 installed in a direction orthogonal to the longitudinal direction of the reinforcing beam 14, and one end of the vertical shaft 22 is fixed to the lower end of the vertical rotation shaft 20. A bevel gear 22 a is attached to the other end of the vertical shaft 22.

  The bevel gear box 19 has a horizontal shaft 21 parallel to the longitudinal direction of the reinforcing beam 14, and one end of the horizontal shaft 21 is fixed to the horizontal bar 18. A bevel gear 21 a that meshes with a bevel gear 22 a attached to the other end of the vertical shaft 22 is attached to the other end of the horizontal shaft 21.

  The vertical rotating shaft 20 is provided with an operation portion 23 at the upper end and a locking nut 24 so as to abut on the upper surface of the reinforcing beam 14. The operation unit 23 has, for example, a rotary operation knob and an opening into which a bolt wrench is inserted at the upper end.

(Work)
Next, the operation of the gap adjustment mechanism 13 will be described.

  First, when the operation unit 23 is operated remotely underwater to rotate the vertical rotation shaft 20, the bevel gear 22 a rotates through the vertical shaft 22. Then, the bevel gear 21a meshing with the bevel gear 22a rotates to rotate the horizontal bar 18 via the horizontal shaft 21.

  Then, by rotating the horizontal bar 18, the horizontal bolt 17 rotates and moves in the horizontal direction with respect to the female screw hole of the additional bracket 11. As a result, the lateral bolt 17 can approach the divider 8 to adjust the gap G2 in the short side direction. After this gap adjustment, the locking nut 24 is rotated to prevent locking.

  Next, the seismic reinforcement method for each spent fuel storage rack 1 will be described.

  In this embodiment, the step of installing the reinforcing beam pedestal 15 on the floor surface 3 of the fuel storage pool 2, the reinforcing beam 14 is disposed at a predetermined height position with respect to the existing horizontal beam 5, and the reinforcing beam pedestal is arranged. 15, the step of adjusting the total length of the reinforcing beam 14 by the projecting member 16, and the short side direction between the divider 8 of the spent fuel storage rack 1 and the additional bracket 11 provided on the reinforcing beam 14. Adjusting the gap G2 by the gap adjusting mechanism 13.

  Specifically, first, the reinforcing beam support 15 is suspended from the upper end of the fuel storage pool 2 and installed at a predetermined position in the fuel storage pool 2. Next, the reinforcing beam 14 is suspended from the upper end of the fuel storage pool 2 and set at a predetermined height position with respect to the existing horizontal beam 5 and then coupled to the reinforcing beam receiving base 15 with a bolt or the like.

  Further, the gap G <b> 2 in the short side direction between the reinforcing beam 14 and the pool side wall 6 is adjusted by the projecting member 16. Thereafter, when the operating portion 23 provided on the upper portion of the gap adjusting mechanism 13 provided in the reinforcing beam 14 is rotated with respect to the divider 8 of the spent fuel storage rack 1 to rotate the vertical rotating shaft 20, the vertical axis The bevel gear 22 a rotates via 22.

  Then, the bevel gear 21a meshing with the bevel gear 22a rotates to rotate the horizontal bar 18 via the horizontal shaft 21. By rotating the horizontal bar 18, the horizontal bolt 17 rotates and moves in the horizontal direction with respect to the female screw hole of the additional bracket 11. And the short side direction gap G2 of the spent fuel storage rack 1 is adjusted to the minimum by pressing the tip of the lateral bolt 17 against the side surface of the divider 8. Thereafter, the locking nut 24 is tightened at the upper part of the vertical rotation shaft 20. This operation is performed for all the gap adjusting mechanisms 13, and the installation is completed.

  In the above installation, the reinforcing beam 14 and the reinforcing beam receiving base 15 can be combined in advance and installed.

(Effect)
According to the present embodiment, the additional bracket 11 for supporting the rack short side direction at the divider 8 position and the underwater remote operation is possible, and the short side direction gap G2 between the divider 8 and the additional bracket 11 is formed. By providing the gap adjusting mechanism 13 for adjusting to the minimum, the short side direction gap G2 is adjusted to the minimum by the gap adjusting mechanism 13 for each spent fuel storage rack 1 with respect to the short side direction seismic force. Therefore, the falling moment applied to the foundation bolt 4 and the tensile force applied to the bolt 7 of the existing horizontal beam 5 can be reduced.

  Further, according to the present embodiment, by operating the gap adjusting mechanism 13 provided in the reinforcing beam 14 from the upper end of the fuel storage pool 2, the short side gap G2 with respect to the divider 8 can be adjusted to the minimum remotely. it can.

(Second Embodiment)
(Constitution)
FIG. 5 is an enlarged sectional view showing a gap adjusting mechanism of the seismic reinforcement structure for a spent fuel storage rack according to the second embodiment of the present invention. FIG. 6 is a plane cross-sectional configuration diagram showing the gap adjusting mechanism of the seismic reinforcement structure of FIG. The same parts as those in the first embodiment will be described using only the same reference numerals and different configurations. The same applies to other embodiments.

  In this embodiment, the short side direction gap G3 with respect to the divider 8 is minimized by the additional bracket 25 and the gap adjustment mechanism 26 provided with the spent fuel storage racks 1 on the reinforcing beam 14 against the seismic force in the rack short side direction. The seismic reinforcement structure is used when the strength member of the gap adjustment mechanism 26 provided in the reinforcing beam 14 needs to have sufficient seismic tolerance because the short side direction seismic force is excessively adjusted and held.

  As shown in FIGS. 5 and 6, the gap adjustment mechanism 26 is supported on the lower surface of the additional bracket 25 fixed to the reinforcing beam 14, and can move horizontally on the support plate 28. A wedge-shaped adjustment block 29 as a horizontally moving member to be supported, a vertical bolt 30 penetrating in a direction perpendicular to the longitudinal direction of the reinforcing beam 14, and a wedge-shaped adjustment rotatably fixed to the lower portion of the vertical bolt 30 A block 31, an adjustment nut 32 screwed into the upper portion of the vertical bolt 30, a presser member 33 that is fixed to the upper surface of the reinforcing beam 14 and restrains the vertical movement of the adjustment nut 32, and a locking nut 34 that is used after adjusting the clearance. And.

  A male screw is engraved on the outer peripheral surface of the vertical bolt 30, and this male screw is screwed into a female screw engraved on the inner peripheral surface of the adjustment nut 32. In this adjustment nut 32, a fixing flange 27 is formed integrally with a small diameter portion. The fixing flange 27 is held by a pressing member 33, and the movement in the vertical direction together with the adjustment nut 32 is restricted. Therefore, when the adjustment nut 32 is rotated underwater remotely, the vertical bolt 30 moves up and down with respect to the vertical direction.

  An adjustment block 31 is rotatably fixed to the lower end of the vertical bolt 30, and the adjustment block 31 moves up and down as the vertical bolt 30 moves up and down. The adjustment block 31 moves up and down along the side surface of the additional bracket 25 when one side surface contacts the side surface of the additional bracket 25.

  On the other side surface of the adjustment block 31, an inclined surface 31a is formed which becomes narrower as it goes in the tip direction. A point-symmetric slope 29 a that contacts the slope 31 a is formed in the adjustment block 29.

(Work)
Next, the seismic reinforcement method of this embodiment is demonstrated. The steps up to the step of installing the reinforcing beam receiving base 15 and the reinforcing beam 14 are the same as those in the first embodiment.

  In this embodiment, in the step of supporting the divider 8 of the spent fuel storage rack 1 by the additional bracket 25 provided on the reinforcing beam 14 and the gap adjusting mechanism 26, the adjustment nut 32 of the gap adjusting mechanism 26 is rotated, The adjustment block 31 fixed to the vertical bolt 30 is lowered, and the adjustment block 29 held on the support plate 28 is pressed against the side surface of the divider 8 of the spent fuel storage rack 1, thereby minimizing the short side direction gap G3. Adjust.

  That is, in this embodiment, when the adjusting nut 32 is rotated in one direction, the adjusting block 31 is lowered together with the vertical bolt 30. At this time, the inclined surface 31 a of the adjusting block 31 presses the inclined surface 29 a of the adjusting block 29. Then, the adjustment block 29 moves in the horizontal direction and approaches the divider 8 to adjust the short side direction gap G3 to a minimum.

  Next, the locking nut 34 at the top of the vertical bolt 30 is tightened to prevent rotation. This operation is performed for all the gap adjusting mechanisms 26, and the installation is completed.

(Effect)
As described above, according to the present embodiment, in addition to the operations and effects of the first embodiment, the adjustment blocks 29 and 31 having sufficient rigidity are used as the strength members of the gap adjusting mechanism 26. It is possible to provide the gap adjustment mechanism 26 having sufficient seismic tolerance against the side direction seismic force.

(Third embodiment)
(Constitution)
FIG. 7 is a longitudinal sectional view showing a seismic reinforcement structure of a spent fuel storage rack according to a third embodiment of the present invention.

  In contrast to the first embodiment and the second embodiment, when it is necessary to reduce the number of parts of the gap adjusting mechanism and simplify the structure, or for reasons such as seismic strength, the reinforcing beam 14 has a through hole. If it is not a good idea to provide this, this embodiment is applied.

  In addition, since the structure which presses the front-end | tip of the horizontal volt | bolt 36 of the clearance gap adjustment mechanism 35 to the divider 8 side surface of the spent fuel storage rack 1 is the same as that of the said 1st Embodiment, the description is abbreviate | omitted.

  In this embodiment, one end of a flexible shaft 37 as a flexible wire is fixed to the back surface of the horizontal bolt 36, and a retaining portion 39 of the horizontal bolt 36 is provided on the side of the additional bracket 38 of the reinforcing beam 14.

(Work)
Therefore, when the flexible shaft 37 is rotationally driven from above the reinforcing beam 14, the horizontal bolt 36 rotates and moves in the horizontal direction with respect to the female screw hole of the additional bracket 38. Thereby, the horizontal bolt 36 approaches the divider 8 remotely in the water, and the gap in the short side direction can be adjusted to the minimum.

(Effect)
As described above, according to this embodiment, the flexible shaft 37 is fixed to the horizontal bolt 36 that receives the rotational force and moves in the horizontal direction, and the flexible shaft 37 can be rotated. Therefore, the construction can be simplified, and since it is not necessary to provide a through hole in the reinforcing beam 14, the construction period can be shortened.

(Other embodiments)
In addition, this invention is not limited to said each embodiment, Each embodiment is combined and a various change is possible. For example, in the first embodiment, the female screw hole of the additional bracket 11 is engraved, and the male screw is engraved on the outer peripheral surface of the lateral bolt 17 in order to be screwed into the female screw hole. Even if a male screw is engraved on the outer peripheral surface of the horizontal bar 18 and a female screw hole is engraved on the inner peripheral surface of the horizontal bolt 17, the horizontal bolt 17 can be moved in the horizontal direction by the rotation of the horizontal bar 18. .

  In the second embodiment, the male screw is engraved on the entire longitudinal direction of the vertical bolt 30. However, the present invention is not limited to this, and the male screw may be engraved only for the stroke in which the vertical bolt 30 moves. Good.

  Further, in the third embodiment, the flexible shaft 37 is fixed to the lateral bolt 36. However, the present invention is not limited to this, and a plurality of long rods having rigidity are connected via a universal joint. Also good. However, in order to simplify the structure, it is desirable to configure as in the third embodiment.

DESCRIPTION OF SYMBOLS 1 ... Spent fuel storage rack, 2 ... Fuel storage pool, 3 ... Floor surface, 4 ... Foundation bolt, 5 ... Horizontal beam, 6 ... Pool side wall, 7 ... Bolt, 8 ... Divider (holding part), 9 ... Bracket 11 ... Additional bracket, 13 ... Gap adjusting mechanism, 14 ... Reinforcement beam, 15 ... Reinforcement beam cradle, 16 ... Stiffening member, 17 ... Horizontal bolt (horizontal movement member), 18 ... Horizontal bar, 19 ... Bevel gearbox , 20 ... vertical rotation axis, 21 ... horizontal axis, 22 ... vertical axis, 23 ... operation part, 24 ... locking nut, 25 ... additional bracket, 26 ... clearance adjustment mechanism, 28 ... support plate, 29 ... adjustment block (Horizontal moving member), 30 ... vertical bolt, 31 ... adjustment block, 32 ... adjustment nut, 33 ... presser member, 34 ... loosening prevention nut, 35 ... clearance adjustment mechanism, 36 ... lateral bolt, 37 ... flexi Spool shaft (flexible wire), 38 ... additional installation bracket, 39 ... retaining portion, G1 ... short side direction gap, G2 ... short side direction gap, G3 ... short side direction gap.

Claims (5)

A structure for seismic reinforcement of a spent fuel storage rack in which a spent fuel storage rack having a rectangular parallelepiped shape in which a plurality of cells each containing spent fuel assemblies are arranged in parallel is seismically reinforced in the fuel storage pool. ,
A reinforcing beam fixed at a height equivalent to a holding portion fixed in the short side direction of the spent fuel storage rack in the fuel storage pool;
An additional bracket fixed to the reinforcing beam and installed on both sides of the holding portion with a gap in the short side direction of the spent fuel storage rack;
A gap adjustment mechanism that adjusts remotely in water so that the gap between the holding portion and the additional bracket is small;
A seismic reinforcement structure for a spent fuel storage rack, comprising:   The gap adjusting mechanism includes a longitudinal rotating shaft that is rotated remotely underwater, and is mechanically connected to the longitudinal rotating shaft and moves in the horizontal direction under the rotational driving force of the longitudinal rotating shaft. The seismic reinforcement structure for a spent fuel storage rack according to claim 1, further comprising a horizontally moving member that reduces the size of the spent fuel storage rack.   The gap adjusting mechanism includes a vertically moving member that can be moved up and down remotely underwater, and a horizontal moving member that moves in the horizontal direction as the vertically moving member descends to reduce the gap. The seismic reinforcement structure for a spent fuel storage rack according to claim 1.   The gap adjusting mechanism includes a flexible wire that can be rotated underwater remotely, and one end of the flexible wire is fixed and receives a rotational driving force of the flexible wire to move in a horizontal direction to reduce the gap. The seismic reinforcement structure for a spent fuel storage rack according to claim 1, further comprising a moving member. A method for seismic reinforcement of a spent fuel storage rack in which a spent fuel storage rack having a rectangular parallelepiped shape in which a plurality of cells each containing spent fuel assemblies are arranged in parallel is seismically reinforced in the fuel storage pool. ,
A reinforcing beam fixing step of fixing a reinforcing beam at a height position equivalent to a holding portion fixed in the short side direction of the spent fuel storage rack in the fuel storage pool;
After the reinforcing beam fixing step, an additional bracket installation step that installs an additional bracket on the both sides of the holding portion that is fixed to the reinforcing beam with a gap in the short side direction of the spent fuel storage rack;
After the additional bracket installation step, a gap adjustment step for adjusting by a gap adjustment mechanism remotely in water so that the gap between the holding portion and the additional bracket is reduced,
A method for seismic reinforcement of a spent fuel storage rack.

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