JP2017110997A - Fuel exchanging fixture for boiling-water reactor and method for exchanging fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel exchanging fixture and a method for exchanging fuel, which enable an exchanging work of fuel assemblies to be performed easily in a boiling-water reactor that includes densely arranged hexagonal fuel assemblies and a Y-shaped control rod inserted between three bodies of the mutually adjacent fuel assemblies, by preventing the Y-shaped control rod totally inserted to prevent criticality of a nuclear reactor, from falling down in a space formed after the fuel assemblies are taken out.SOLUTION: A fuel exchanging fixture 41 engages with a control rod stopper 42 provided on an upper end portion of a predetermined wing 31a, among three wings 31a, 31b, and 31c, of a Y-shaped control rod 30 so as to protrude upward and two fuel assembly stoppers 43 provided on upper end portions of each of two bodies of fuel assemblies 20f and 20g, among the three bodies of the fuel assemblies, adjacent to the predetermined wing, thereby restricting a horizontal movement of the control rod stopper with respect to the assembly stoppers.SELECTED DRAWING: Figure 1

Description

  The present invention is for refueling a boiling water nuclear reactor comprising a densely arranged hexagonal fuel assembly and a Y-shaped control rod inserted between three adjacent fuel assemblies. The present invention relates to a jig and a fuel exchange method.

  FIG. 18 shows a longitudinal sectional view of a conventional boiling water reactor. A plurality of fuel assemblies 20 are loaded in the reactor core 2 located in the center of the reactor pressure vessel 1.

  FIG. 19 shows a longitudinal sectional view of the nuclear reactor core 2. The fuel assembly 20 includes a fuel rod 21, a spacer 22, an upper tie plate 23, a lower tie plate 24, a channel box 25, and the like. The lower part (lower tie plate 24) of the fuel assembly 20 is fitted and supported in one of four upper openings 27 provided in the fuel support fitting 26. The weight of the fuel assembly 20 is received by the end plate of the reactor pressure vessel 1 through the fuel support fitting 26, the control rod guide tube 4, the control rod drive mechanism housing 5, and the control rod drive mechanism stub tube 6. A control rod moving opening 28 is provided at the center of the fuel support fitting 26 so that the cross-shaped control rod 3 can be moved up and down. The upper part (upper tie plate 23) of the fuel assembly 20 is restrained from moving in the horizontal direction by the upper lattice plate 11 installed on the upper part of the reactor core 2. The upper lattice plate 11 also has a role of guiding and positioning when the fuel assembly 20 is loaded on the reactor core 2.

  FIG. 20 shows a horizontal sectional view of the reactor core 2. As shown in FIG. 20, a cross-shaped control rod 3 is disposed between four fuel assemblies 20 adjacent to each other, and a neutron instrumentation pipe 7 is installed near the position where the cross-shaped control rod 3 is disposed. Has been.

  Although the nuclear reactor is operated by fission of fuel in the fuel assembly, the proportion of uranium 235 that undergoes fission decreases with the passage of operating time, so it is necessary to systematically replace the fuel with a new one.

  A conventional method for exchanging fuel in a boiling water reactor will be described with reference to FIG. FIG. 21 shows how the four fuel assemblies 20a to 20d arranged in one lattice of the upper lattice plate 11 are replaced. Hereinafter, the replacement procedure will be described in order.

  (1) Remove the top cover of the reactor pressure vessel, remove the reactor internals such as the steam dryer and steam separator at the top of the reactor core, and open the top of the reactor core (see FIG. 21A). In the conventional boiling water nuclear reactor, the upper lattice plate 11 is not removed at the time of fuel exchange, so that the upper portions of the four fuel assemblies 20a to 20d are restrained from moving in the horizontal direction by the upper lattice plate 11. The cross-shaped control rod 3 is supported by rollers (not shown) provided on both side surfaces of the four blades contacting the outer peripheral surfaces of the fuel assemblies 20a to 20d.

  (2) Two fuel assemblies 20a and 20c arranged diagonally with the cross-shaped control rod 3 as the center are taken out from the reactor core (see FIG. 21B). At this time, since the cross-shaped control rod 3 is supported by the remaining two fuel assemblies 20b and 20d arranged on the diagonal line, there is no risk of falling.

  (3) A double blade guide 70 formed by connecting two dummy fuel assemblies 60A, 60c in a space formed after the fuel assemblies 20a, 20c are taken out (shown by hatching in the drawing) 21 (c)).

  (4) Remove the remaining two fuel assemblies 20b and 20d from the reactor core (see FIG. 21 (d)). At this time, the cross-shaped control rod 3 is supported by the two dummy fuel assemblies 60a and 60c arranged on the diagonal line, and there is no possibility of falling.

  (5) Pull out the cross-shaped control rod 3 from the lower side of the reactor core (see FIG. 21E), and take out the double blade guide 70 from the reactor core (see FIG. 21F).

  (6) When installing the fuel assemblies 20a to 20d incorporating the new fuel, the steps (1) to (5) are performed in reverse.

  When the fuel assembly is loaded, the core support plate 12 and the fuel support fitting 26 are installed at the lower part of the reactor core, and the upper lattice plate 11 is installed at the upper part of the reactor core (6. ) Only.

  FIG. 22 shows a horizontal sectional view of the light water breeder reactor core. A light water breeding reactor is a boiling water reactor in which fuel assemblies are densely arranged to reduce the water-to-fuel volume ratio, and by increasing the plutonium breeding ratio compared to conventional boiling water reactors, The consumption and generation amount of fissile plutonium during the operation of the furnace can be made substantially the same (growth ratio is about 1.0). As shown in FIG. 22, the fuel assembly 20 includes a hexagonal channel box 25 and a plurality of fuel rods 21 arranged in a triangular lattice pattern in the channel box 25. A Y-shaped control rod 30 is disposed between the fuel assemblies 20.

  FIG. 23 shows a longitudinal sectional view of the light water breeder reactor core. The fuel assembly 20 includes a fuel rod (not shown), a spacer (not shown), an upper tie plate 23, a lower tie plate 24, a channel box 25, and the like. The lower tie plate 24 of the fuel assembly 20 is fitted and supported in one of three upper openings 27 provided in the fuel support fitting 26. The weight of the fuel assembly 20 is the same as that of the conventional boiling water reactor through the fuel support fitting 26, the control rod guide tube, the control rod drive mechanism housing, and the control rod drive mechanism stub tube. I'm receiving it on the end panel. A control rod moving opening 28 is provided at the center of the fuel support fitting 26 so that the Y-shaped control rod 30 can be moved up and down. The upper portion of the fuel assembly 20 (upper tie plate 23) is an upper support mechanism called a hold-down spring provided between the upper lattice plate 11 having a flow path smaller than the cross sectional area of the fuel assembly and the upper tie plate 23. 34 is supported by fitting.

  Patent Document 1 discloses a reactor core having a hexagonal fuel assembly in which fuel rods are arranged in a triangular lattice shape, and a Y-shaped control rod having three blades inserted between them and having a blade interval of 120 degrees. A fuel exchange jig used when replacing the fuel assembly of the two, wherein two hexagonal fuel assemblies located on an extension line of two blades of the Y-shaped control rod, and the Y-shaped control rod, There is disclosed a fuel change jig having a plurality of fitting portions for joining the two.

  Patent Document 2 discloses a plurality of fuel rods arranged in a lattice shape, a plurality of spacers for maintaining the interval between the fuel rods, an upper tie plate that supports the upper ends of the fuel rods, and a lower type that supports the lower ends of the fuel rods. In the core of a boiling water reactor comprising a plurality of fuel assemblies provided with rates and a plurality of fuel support fittings having openings for mounting the lower tie plates of the fuel assemblies, the fuel support fittings A core of a boiling water reactor is disclosed, in which positioning means for arranging the position of the lower tie plate in the horizontal rotation direction at a set position is provided.

  Patent Document 3 discloses a fuel assembly in which a large number of fuel tanks are arranged in a square lattice and covered by a channel box, and plate-shaped wings are combined in a cross shape in a gap in which the fuel assemblies are arranged in a square lattice. A control member that surrounds the fuel assembly with the blades and is disposed so as to be movable up and down, and a spacing member disposed at an upper portion between the fuel assemblies. A reactor core superstructure is disclosed in which the holding member can be removed.

JP 2007-93475 A JP 2005-221326 A JP-A 64-65496

  In the conventional boiling water reactor, as shown in FIG. 19, the upper part of the fuel assembly 20 is restrained from moving in the horizontal direction by the upper lattice plate 11 even when the fuel is changed, as shown in FIG. Even if two fuel assemblies 20a and 20c arranged diagonally with the cross-shaped control rod 3 as the center are taken out, the cross-shaped control rod 3 is supported by the remaining two fuel assemblies 20b and 20d. Therefore, there is no possibility that the cross-shaped control rod 3 will fall.

  However, in the light water breeding reactor shown in FIG. 22, if any one of the three fuel assemblies 20 adjacent to the Y-shaped control rod 30 is taken out, the Y-shaped control rod 30 falls in the space formed after the removal. There is a risk. Therefore, in the light water breeder reactor, it is necessary to take another means for preventing the Y-shaped control rod from overturning at the time of fuel exchange.

  The fuel replacement jig and the fuel replacement method described in Patent Document 1 include a fuel assembly guide tube and a Y-shaped control rod that enable accurate positioning of the upper portion of the fuel assembly by contacting the upper lattice plate of the core. Boiling water type atoms with a core structure that does not have a core upper grid plate and a fuel assembly guide tube because it prevents the Y-shaped control rod from overturning by connecting with a fuel change jig Not applicable to furnaces.

  Patent Document 2 describes a light water breeder reactor in which fuel rods and fuel assemblies are densely arranged to reduce the water-to-fuel volume ratio, but does not describe prevention of overturning of Y-shaped control rods.

  Patent Document 3 relates to a K-lattice core in which control members are arranged on four sides of a large fuel assembly in which the number of fuel rods is increased as compared with the prior art. It does not relate to light water breeding reactors with a reduced volume ratio.

  The present invention has been made in view of the above circumstances, and its purpose is a Y-shape inserted between a densely arranged hexagonal fuel assembly and three fuel assemblies adjacent to each other. In a boiling water reactor equipped with a type control rod, a Y-type control rod that is fully inserted in order to prevent the criticality of the reactor is prevented from falling into a space that can be formed after the fuel assembly is removed. Accordingly, it is an object of the present invention to provide a fuel replacement jig and a fuel replacement method that facilitate the replacement operation of the fuel assembly.

  In order to solve the above-described problems, the present invention provides a boil comprising densely arranged hexagonal fuel assemblies and Y-shaped control rods inserted between three fuel assemblies adjacent to each other. In a fuel exchange jig for a water reactor, a first stopper provided to project upward from an upper end portion of a predetermined blade among the three blades of the Y-shaped control rod, and the three fuels A fuel replacement jig is provided with a second stopper that protrudes upward from the upper end portion of at least one of the two fuel assemblies adjacent to the predetermined blade among the assemblies. It is assumed that the first stopper is configured to engage with the second stopper and restrain the horizontal movement of the first stopper with respect to the second stopper.

  According to the present invention, in a boiling water reactor comprising a densely arranged hexagonal fuel assembly and a Y-shaped control rod inserted between three fuel assemblies adjacent to each other, In order to prevent the criticality of the nuclear reactor, the upper end portion of the Y-shaped control rod that is fully inserted is fixed to the upper end portion of at least one of the two fuel assemblies that are not to be replaced. The Y-shaped control rod does not fall over in the space created after the fuel is taken out, and the replacement work of the fuel assembly becomes easy.

1 is a top view of a fuel assembly equipped with a fuel replacement jig in a first embodiment of the present invention. FIG. FIG. 3 is an upper side view of the fuel assembly equipped with the fuel replacement jig in the first embodiment of the present invention (a view taken along the line AA in FIG. 1). It is a top view of the fuel assembly before mounting the fuel replacement jig in the first embodiment of the present invention. FIG. 5 is a top side view of the fuel assembly before mounting the fuel replacement jig according to the first embodiment of the present invention (a view taken along the line BB in FIG. 3). It is a three-view figure of the jig | tool for fuel replacement | exchange in the 1st Example of this invention. It is a figure which shows the fuel exchange method of the boiling water reactor in the 1st Example of this invention. It is a three-view figure of the jig | tool for fuel replacement | exchange in the 1st modification of the 1st Example of this invention. FIG. 6 is a top view of a fuel assembly equipped with a fuel replacement jig in a second modification of the first embodiment of the present invention. It is a top view of the jig for fuel exchange in the 2nd modification of the 1st example of the present invention. It is a top view of the fuel assembly which equipped with the jig for fuel exchange in the 2nd example of the present invention. FIG. 10 is a top view of a fuel assembly equipped with a fuel replacement jig in a third embodiment of the present invention. FIG. 10 is a top view of a fuel assembly equipped with a fuel replacement jig in a fourth embodiment of the present invention. It is a three-view figure of the jig for fuel replacement | exchange in the 4th Example of this invention. It is a top view of the fuel assembly which equipped with the jig for fuel exchange in the 5th example of the present invention. It is the elements on larger scale near the jig for fuel replacement | exchange in FIG. It is a top side view (CC arrow line view of FIG. 14) of the fuel assembly which mounted | worn with the jig | tool for fuel replacement | exchange in the 5th Example of this invention. It is a three-view figure of the jig for fuel replacement | exchange in the 5th Example of this invention. It is a longitudinal cross-sectional view of the conventional boiling water reactor. It is a longitudinal cross-sectional view of the conventional boiling water reactor core. It is a horizontal sectional view of the conventional boiling water reactor core. It is a figure which shows the fuel exchange method of the conventional boiling water reactor. It is a horizontal sectional view of the light water breeding reactor core in the example of the present invention. It is a longitudinal cross-sectional view of the light water breeding reactor core in the Example of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same member and the overlapping description is abbreviate | omitted suitably.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a top view of a fuel assembly equipped with a fuel replacement jig in this embodiment, and FIG. 2 is an upper side view of the fuel assembly equipped with a fuel replacement jig in this embodiment (FIG. 1). 3 is a top view of the fuel assembly before mounting the fuel replacement jig in the present embodiment, and FIG. 4 is for fuel replacement in the present embodiment. FIG. 5 is a top side view of the fuel assembly before mounting the jig (a view taken along the line B-B in FIG. 3), FIG. It is a figure which shows the fuel replacement | exchange method of the boiling water reactor in a present Example.

  1 to 4 and FIG. 6 show that among several hundred fuel assemblies loaded in a nuclear reactor core, three fuel assemblies adjacent to each other and a Y-shaped control rod arranged therebetween. Show. A fuel assembly contact prevention pad for preventing contact with the adjacent fuel assembly 20 is located near the upper ends of the four side surfaces that do not face the blades of the Y-shaped control rod 30 among the six side surfaces of the fuel assembly 20. 33 is provided, and in the vicinity of the upper ends of the two side surfaces facing the blades of the Y-shaped control rod 30, contact with the adjacent fuel assembly 20 is prevented in consideration of the thickness of the Y-shaped control rod 30. For this purpose, a Y-shaped control rod insertion portion fuel assembly contact prevention pad 32 is provided.

  As shown in FIGS. 22 and 23, a boiling water reactor to which the present invention is applied is arranged between a densely arranged hexagonal fuel assembly 20 and three fuel assemblies 20 adjacent to each other. And a Y-shaped control rod 30 to be inserted. Note that the present invention is also applicable to a boiling water reactor having a core structure that does not include the upper lattice plate 11 and the upper support mechanism 34 shown in FIG.

  The feature of this embodiment is that when replacing any one of the three fuel assemblies 20 adjacent to the Y-shaped control rod 30, the fuel-changing jig 41 is used to replace the Y-shaped control rod 30. The upper end portion is fixed to the upper end portions of the two fuel assemblies 20 that are not to be replaced.

  As shown in FIG. 3, two of the six corners of the upper part (upper tie plate) of the fuel assembly 20 that are closest to the tips of any of the three blades 31 a to 31 c of the Y-shaped control rod 30 are shown. At the corner portions, fuel assembly stoppers 43 are provided so as to protrude upward. Therefore, at the time of fuel replacement in the present embodiment, the two fuel assembly stoppers 43 are in the directions closest to the tips of any of the three blades 31a to 31c of the Y-shaped control rod 30, respectively. Need to be installed. The present invention is not limited to this, and fuel assembly stoppers 43 may be provided at all six corners. In this case, the fuel assembly 20 can be arranged in any direction.

  The fuel assembly stopper 43 is formed of a cylindrical member, and has a tip that is tapered so that it can be easily inserted into the fuel assembly stopper insertion opening 45 of the fuel replacement jig 41 shown in FIG. ing. The shape of the fuel assembly stopper 43 may be an elliptical columnar shape, a cylindrical shape, or a prismatic shape in addition to a columnar shape. The height dimension of the fuel assembly stopper 43 is such that the upper portion of the fuel assembly stopper 43 protrudes from the upper surface of the fuel replacement jig 41 when the fuel replacement jig 41 is mounted as shown in FIG. Is set.

  Further, as shown in FIG. 3, a control rod stopper is mounted on the upper end of each of the three blades 31a to 31c of the Y-shaped control rod 30 so that the control rod stopper 42 protrudes upward. A hole 47 is provided. At the time of fuel replacement, a control rod stopper 42 is attached to the upper end of the blade of the Y-shaped control rod 30 disposed between the two fuel assemblies 20 to which the fuel replacement jig 41 is attached. In the example shown in FIG. 1, the control rod stopper 42 is attached only to the upper end portion of one blade 31 a of the Y-shaped control rod 30. Control rod stoppers 42 may be attached to all of the blades 31a to 31c. FIG. 3 shows a convex fitting provided at the lower end of the control rod stopper 42 in a concave fitting portion (control rod stopper mounting hole 47) provided at the upper end of the wing of the Y-shaped control rod 30. Although the structure which fits a joint part is shown, this invention is not limited to this, The fitting provided in the upper end part of the wing | blade of the Y-shaped control rod 30 and the lower end part of the stopper 42 for control rods The concavity and convexity at the joint may be reversed. During normal operation of the nuclear reactor, the vertical movement of the Y-shaped control rod 30 between the fuel assemblies 20 may be hindered, so the control rod stopper 42 is removed. The height of the control rod stopper 42 is such that the upper end position of the control rod stopper 42 when attached to the upper end of the blade of the Y-shaped control rod 30 is the upper end of the fuel assembly stopper 43 as shown in FIG. The upper portion of the control rod stopper 42 is similar to the fuel assembly stopper 43 from the upper surface of the fuel replacement jig 41 when the fuel replacement jig 41 is mounted. Stick out.

  As shown in FIG. 5, the fuel changing jig 41 includes a control rod stopper insertion opening 44 for inserting the control rod stopper 42 and two fuel insert stoppers 43 for inserting the two fuel assembly stoppers 43, respectively. And two fuel assembly stopper insertion openings 45. The corners of the control rod stopper insertion opening 44 and the fuel assembly stopper insertion opening 45 are tapered or rounded so that the control rod stopper 42 or the fuel assembly stopper 43 can be easily inserted. Is formed. Since the fuel change jig 41 is moved and mounted by using a newly installed fuel changer (crane), two suspensions for gripping by the gripping portion of the fuel changer (crane) are provided on the upper surface of the fuel change jig 41. A portion 46 is provided. The position of the hanging part 46 is not particularly limited. The planar shape of the fuel changing jig 41 is trapezoidal so as not to interfere with the handle 35 provided at the upper end of the fuel assembly 20 shown in FIGS. In this embodiment, fuel is supplied to the control rod stopper 42 provided at the upper end portion of the blade of the Y-shaped control rod 30 and the fuel assembly stopper 43 provided at the corner portion of the upper end portion of the fuel assembly 20. The replacement jig 41 is engaged, but the present invention is not limited to this. The control rod stopper 42 and the fuel assembly stopper 43 are integrally formed on the fuel replacement jig 41 to control the control rod. The stopper 42 and the fuel assembly stopper 43 may be fitted into a fitting portion provided at the upper end portion of the blade of the Y-shaped control rod 30 and a fitting portion provided at the corner portion of the fuel assembly 20, respectively. .

  At the time of fuel replacement, as shown in FIG. 1, the control rod stopper 42 and the two fuel assemblies are inserted into the two fuel assembly stopper insertion openings 45 of the control rod stopper insertion opening 44 and the fuel replacement jig 41. The fuel replacement jig 41 is mounted on the upper end portion of the fuel assembly 20 by inserting the stoppers 43 for the fuel.

  Next, a fuel replacement method for the boiling water reactor in this embodiment will be described with reference to FIG. FIG. 6 shows how three fuel assemblies 20e to 20g arranged adjacent to the Y-shaped control rod 30 are replaced. Hereinafter, the replacement procedure will be described in order.

  (1) Remove the top cover of the reactor pressure vessel, remove the reactor internals such as the steam dryer and steam separator at the top of the reactor core, and open the top of the reactor core. At this time, the Y-shaped control rod 30 is fully inserted between the three fuel assemblies 20e to 20g in order to prevent the criticality of the nuclear reactor.

  (2) The control rod stopper 42 is attached to the upper end portion (control rod stopper mounting hole 47) of the blade of the Y-shaped control rod 30 disposed between the two fuel assemblies 20f and 20g that are not to be replaced. .

  (3) The two suspension parts 46 of the fuel exchange jig 41 are grasped by the grip part of the fuel changer (crane), and the fuel exchange jig 41 is moved to above the mounting position.

  (4) The fuel change jig 41 is lowered, and the control rod stopper 42 and the two fuel assembly stoppers 43 are respectively inserted into the control rod stopper insertion opening 44 and the two fuel assembly stopper insertion openings 45. The control rod stopper 42 is restrained from moving horizontally with respect to the two fuel assembly stoppers 43 (see FIG. 6A). Thereby, the upper end portion of the Y-shaped control rod 30 is fixed to the upper end portions of the two fuel assemblies 20f and 20g. In addition, each corner | angular part of the three opening parts 44, 45, 45 of the fuel change jig | tool 41 is formed in the taper shape or R shape, and each front-end | tip part of the three stoppers 42, 43, 43 is formed. Since it is formed in a taper shape, even when the positions of the three openings 44, 45, 45 are slightly deviated from the three stoppers 42, 43, 43 when the fuel exchange jig 41 is mounted from above. Three stoppers 42, 43, 43 can be inserted into the three openings 44, 45, 45, respectively.

  (5) The fuel assembly 20e not equipped with the fuel replacement jig 41 is taken out, and a dummy fuel assembly (a portion indicated by hatching in the drawing) 60e is installed in a space formed after the removal.

  (6) The mounting position of the fuel exchange jig 41 is changed to the upper ends of the fuel assemblies 60e and 20g in the same procedure as the above (2) to (4) (see FIG. 6B).

  (7) The fuel assembly 20f is taken out, and the dummy fuel assembly 60f is installed in a space formed after the fuel assembly 20f is taken out.

  (8) The mounting position of the fuel replacement jig 41 is changed to the upper end portions of the fuel assemblies 60e and 60f in the same procedure as the above (2) to (4) (see FIG. 6C).

  (9) The fuel assembly 20g is taken out, and the dummy fuel assembly 60g is installed in a space formed after the fuel assembly 20g is taken out.

  (10) Remove the fuel exchange jig 41 and the control rod stopper 42 (see FIG. 6D).

  (11) The Y-shaped control rod 30 is pulled out from the lower side of the reactor core (see FIG. 6E), and the dummy fuel assemblies 60e to 60f are taken out from the reactor core.

  (12) When installing the fuel assemblies 20e, 20f, and 20g incorporating the new fuel, the above procedures (1) to (12) are reversed.

  When the fuel assembly is loaded, only the procedure (12) is performed with the core support plate and the fuel support fittings installed in the lower part of the reactor core.

  According to this embodiment, the control rod stopper 42 and the two fuel assembly stoppers 43 are provided in the control rod stopper insertion opening 44 and the two fuel assembly stopper insertion openings 45 of the fuel changing jig 41. Two fuels whose upper ends of the Y-shaped control rods 30 are not to be replaced are inserted by restraining the horizontal movement of the control rod stoppers 42 with respect to the two fuel assembly stoppers 43. It is fixed to the upper ends of the aggregates 20f, 20g. As a result, the Y-shaped control rod 30 will not fall over in the space created after the fuel assembly 20e to be replaced is taken out, and the replacement operation of the fuel assembly 20e becomes easy.

  Further, since the position of the control rod stopper 42 and the positions of the two fuel assembly stoppers 43 and 43 are close to each other, it is easy to align the fuel changing jig 41 by the fuel changer (crane). .

  A first modification of the present embodiment will be described with reference to FIG. FIG. 7 is a three-side view of the fuel replacement jig in the present modification.

  The feature of this modification is that the upper portions of the two suspension portions 46 provided on the fuel exchange jig 41 in this embodiment are connected to each other, and a suspension portion is formed substantially above the center of the fuel exchange jig 41. is there.

  According to this modification, when the fuel exchange jig 41 is aligned, the gap between the grip part of the fuel changer (crane) that grips the suspension part 46A and the handle 35 of the upper tie plate 23 is increased. The possibility that the gripping part of the exchange (crane) contacts the handle 35 of the upper tie plate 23 can be reduced.

  A second modification of the present embodiment will be described with reference to FIGS. FIG. 9 is a top view of the fuel assembly equipped with the fuel replacement jig in the present modification, and FIG. 8 is a plan view of the fuel replacement jig in the present modification.

  The feature of this modification is that the three fuel change jigs 41 are connected to each other so that the three fuel change jigs 41 can be moved or mounted at a time.

  As shown in FIG. 9, the three fuel replacement jigs 41 </ b> A to 41 </ b> C are connected to each other by a connecting member 80. The connecting member 80 includes a main body portion 81 formed in a substantially equilateral triangle shape, three leg portions 82 a to 82 c provided so as to protrude downward from each corner portion of the main body portion 81, and the upper surface center position of the main body portion 81. And a hanging portion 83 provided on the surface. The lower end portions of the leg portions 82a to 82c are connected to the suspension portions 46 of the three fuel exchange jigs 41A to 41C, respectively. The height of the legs 82a to 82c is set so that the main body 81 does not interfere with the handle 35 above the fuel assembly 20 when the three fuel exchange jigs 41A to 41C are mounted.

  As shown in FIG. 8, the upper ends of the Y-shaped control rods 30a are fixed to the upper ends of the two fuel assemblies 20e and 20f by the fuel changing jig 41A, and the Y-shaped by the fuel changing jig 41B. The upper ends of the control rods 30b are fixed to the upper ends of the two fuel assemblies 20h and 20i, and the upper ends of the Y-shaped control rods 30c of the two fuel assemblies 20k and 20m are fixed by the fuel changing jig 41C. Fixed to the upper end. As a result, the Y-shaped control rods 30a, 30b, and 30c do not fall over in the space created after the fuel assemblies 20e, 20j, and 20l are taken out, and the replacement of the fuel assemblies 20e, 20j, and 20l is easy. Become.

  According to this modification, the three fuel replacement jigs 41A to 41C can be moved or mounted at a time, and three fuel replacement jigs 41A to 41C can be mounted once for the three fuel replacement jigs 41A to 41C. The aggregates 20e, 20j, and 20l can be exchanged. As a result, the efficiency of the fuel exchange operation can be greatly improved in the core in which several hundred fuel assemblies 20 are loaded. In addition, in this modification, it was set as the structure which connects the three fuel exchange jigs 41, However, It is good also as a structure which connects the 2 or 4 or more fuel exchange jigs 41. FIG.

  A second embodiment of the present invention will be described with reference to FIG. FIG. 10 is a plan view of the upper part of the fuel assembly equipped with the fuel replacement jig in this embodiment.

  The feature of this embodiment is that the control rod stopper insertion opening 44 and the two fuel assembly stopper insertion openings 45 in the first embodiment are formed as one body.

  As shown in FIG. 10, the fuel changing jig 41D has a substantially isosceles triangular control rod / fuel assembly stopper insertion opening into which a control rod stopper 42 and two fuel assembly stoppers 43 can be inserted. Part 48. The corners of the control rod / fuel assembly stopper insertion opening 48 are tapered or rounded so that the control rod stopper 42 and the two fuel assembly stoppers 43 can be easily inserted. Accordingly, even when the position of the opening 48 is slightly shifted from the three stoppers 42, 43, 43 when the fuel exchange jig 41 </ b> D is mounted from above, the stoppers 42, 43, 43 are moved to the opening 48. Can be inserted.

  According to the present embodiment, the control rod stopper 42 and the two fuel assembly stoppers 43 are inserted into the control rod / fuel assembly stopper insertion opening 48 of the fuel exchange jig 41D, and the two fuel assemblies are inserted. By restricting the horizontal movement of the control rod stopper 42 with respect to the stopper 43, the upper end of the Y-shaped control rod 30 is aligned with the upper ends of the two fuel assemblies 20f and 20g not to be replaced. Fixed. As a result, the Y-shaped control rod 30 will not fall over in the space created after the fuel assembly 20e to be replaced is taken out, and the replacement operation of the fuel assembly 20e becomes easy.

  Furthermore, there are six points (three stoppers 42, 43, 43 and three openings 44, 45, 45) to be confirmed when the fuel exchange jig 41D is mounted in the first embodiment. In this embodiment, since there are four points (three stoppers 42, 43, 43 and one opening 48), the mounting operation of the fuel changing jig 41E is facilitated.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 11 is a plan view of the upper part of the fuel assembly equipped with the fuel replacement jig in this embodiment.

  The feature of the present embodiment is that the upper end portion of the Y-shaped control rod 30 is fixed only to one upper end portion of the two fuel assemblies 20 that are not to be replaced.

  As shown in FIG. 11, the fuel replacement jig 41E is either a control rod stopper 42 or one of two fuel assemblies 20f and 20g that are not to be replaced (in this embodiment, the fuel assembly 20g). A control rod and fuel assembly stopper insertion opening 48A having a substantially right triangle shape into which the fuel assembly stopper 43 provided at the upper end can be inserted. However, the present invention is not limited to this, and the control rod stopper insertion opening and the fuel assembly stopper insertion opening may be provided individually, as in the first embodiment.

  According to this embodiment, the control rod stopper 42 and the fuel assembly stopper 43 are inserted into the control rod / fuel assembly stopper insertion opening 48A of the fuel replacement jig 41E, and the fuel assembly stopper 43 is inserted. On the other hand, by restricting the movement of the control rod stopper 42 in the horizontal direction, one of the two fuel assemblies 20f and 20g whose upper end portion of the Y-shaped control rod 30 is not to be replaced (this embodiment) In the example, it is fixed to the upper end of the fuel assembly 20g). As a result, the Y-shaped control rod 30 will not fall over in the space created after the fuel assembly 20e to be replaced is taken out, and the replacement operation of the fuel assembly 20e becomes easy.

  Furthermore, compared to the first or second embodiment, the size of the fuel exchange jig 41E is reduced to about half, and the number of stoppers 43 provided on the fuel assemblies 20e, 20f, 20g is reduced from two to one. Therefore, material costs and processing costs can be reduced. In addition, the points to be checked when the fuel change jig 41E is mounted are 6 points (three stoppers and three openings) in the first embodiment, and four points (three stoppers and three stoppers) in the second embodiment. In contrast to the single opening 48), in this embodiment, there are three points (two stoppers 42 and 43 and one opening 48), so that the mounting operation of the fuel changing jig 41E is further facilitated. Become.

  A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a three-side view of the fuel replacement jig in the present embodiment. FIG. 13 is a plan view of the upper portion of the fuel assembly equipped with the fuel replacement jig in the present embodiment.

  The feature of the present embodiment is that the upper end portion of the Y-shaped control rod 30 is attached to the two fuel assemblies by sandwiching the control rod stopper 42 and the two fuel assembly stoppers 43 with the fuel changing jig 41F. It is fixing to the upper end part of 20.

  As shown in FIG. 12, the fuel exchange jig 41F is a U-shaped plate-like member, and the corner inside the fuel exchange jig 41F is formed in a taper shape or an R shape. . Accordingly, when the fuel change jig 41F is mounted from above, even if the horizontal position of the fuel change jig 41F is slightly deviated from the three stoppers 42, 43, 43, the stoppers 42, 43, 43 Can be sandwiched between the fuel change jigs 41F, so that the fuel change jig 41F can be easily attached.

  According to the present embodiment, the control rod stopper 42 and the two fuel assembly stoppers 43 are sandwiched by the fuel changing jig 41F, and the control rod stopper 42 is placed horizontally with respect to the two fuel assembly stoppers 43. By restricting the movement in the direction, the upper end portion of the Y-shaped control rod 30 is fixed to the upper end portions of the two fuel assemblies 20f and 20g that are not to be replaced. As a result, the Y-shaped control rod 30 will not fall over in the space created after the fuel assembly 20e to be replaced is taken out, and the replacement operation of the fuel assembly 20e becomes easy. In this embodiment, the control rod stopper 42 and the two fuel assembly stoppers 43 are sandwiched by the fuel replacement jig 41F. However, the present invention is not limited to this, and the control rod stopper 42 is provided. And either one of the fuel assembly stoppers 43 may be sandwiched.

  A fifth embodiment of the present invention will be described with reference to FIGS. 14 is a top view of the fuel assembly equipped with the fuel replacement jig in the embodiment, FIG. 15 is a partially enlarged view of the vicinity of the fuel replacement jig 41 in FIG. 14, and FIG. FIG. 17 is a top side view of the fuel assembly equipped with the fuel replacement jig in the example (a view taken along the line CC in FIG. 14), and FIG. 17 is a three-side view of the fuel replacement jig in the present example. .

  A feature of the present embodiment is that a Y-type control rod is obtained by fitting a fuel exchange jig 41G into a groove provided at the upper end of each of the control rod stopper 42A and the two fuel assembly stoppers 43A. 30 is fixed to the upper ends of the two fuel assemblies 20.

  As shown in FIG. 17, the fuel exchange jig 41G is formed by bending a rod-shaped member at four locations. As shown in FIGS. 15 to 17, the control rod stopper groove 49 provided on the upper end surface of the control rod stopper 42A and the two fuel assemblies provided on the upper end surfaces of the two fuel assembly stoppers 43A, respectively. By fitting the fuel replacement jig 41G into the body stopper groove 50, the control rod stopper 42A can be restrained from moving in the horizontal direction with respect to the two fuel assembly stoppers 43A. Further, as shown in FIG. 17, by making the depths of the control rod stopper groove 49 and the two fuel assembly stopper grooves 50 larger than the diameter of the fuel replacement jig 41G, the fuel replacement jig 41G It is possible to prevent the fuel assembly stopper groove 50 or the control rod stopper groove 49 from coming off.

  According to this embodiment, the fuel change jig 41G is fitted into the control rod stopper groove 49 and the two fuel assembly stopper grooves 50, and the control rod use is made with respect to the two fuel assembly stoppers 43A. By restricting the movement of the stopper 42A in the horizontal direction, the upper end portion of the Y-shaped control rod 30 is fixed to the upper end portions of the two fuel assemblies 20f and 20g that are not replacement targets. As a result, the Y-shaped control rod 30 will not fall over in the space created after the fuel assembly 20e to be replaced is taken out, and the replacement operation of the fuel assembly 20e becomes easy. In this embodiment, the fuel exchange jig 41G is fitted into the control rod stopper groove 49 and the two fuel assembly stopper grooves 50. However, the present invention is not limited to this, and the control is performed. It is good also as a structure fitted to the stopper groove | channel 49 for rods, and the stopper groove | channel 50 for any one fuel assembly.

  The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, or the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Reactor core, 3 ... Cross-shaped control rod, 4 ... Control rod guide tube, 5 ... Control rod drive mechanism housing, 6 ... Control rod drive mechanism stub tube, 7 ... Neutron instrumentation piping 11 ... Upper lattice plate, 12 ... Core support plate, 20, 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, 20l, 20m ... Fuel assembly, 21 ... Fuel rod, 22 ... Spacer, 23 ... Upper tie plate, 24 ... Lower tie plate, 25 ... Channel box, 26 ... Fuel support bracket, 27 ... Upper opening, 28 ... Opening for control rod movement, 30, 30a, 30b, 30c ... Y-shaped control rod, 31a, 31b, 31c ... Wings, 32 ... Y-shaped control rod insertion portion fuel assembly contact prevention pad, 33 ... Fuel assembly contact prevention pad, 34 ... Upper support mechanism, 35 ... Han 41, 41A, 41B, 41C, 41D, 41E, 41F, 41G ... Fuel changing jig, 42,42A ... Control rod stopper (first stopper), 43,43A ... Fuel assembly stopper (first) 2), 44 ... Control rod stopper insertion opening (first opening), 45 ... Fuel assembly stopper insertion opening (second opening), 46, 46A ... Hanging portion, 47 ... Control Rod stopper mounting hole, 48, 48A ... Control rod / fuel assembly stopper insertion opening, 49 ... Control rod stopper groove (first groove), 50 ... Fuel assembly stopper groove (second groove) , 60a, 60c, 60e, 60f, 60g ... dummy fuel assemblies, 70 ... double blade guides, 80 ... connecting members, 81 ... main body, 82a, 82b, 82c ... legs, 83 ... hanging parts.

Claims (7)

In a boiling water reactor fuel exchange jig comprising a densely arranged hexagonal fuel assembly and a Y-shaped control rod inserted between three fuel assemblies adjacent to each other,
Of the three wings of the Y-shaped control rod, a first stopper provided to project upward at the upper end of a predetermined wing, and 2 adjacent to the predetermined wing among the three fuel assemblies A second stopper projecting upward from an upper end of a predetermined fuel assembly of at least one of the fuel assemblies is engaged through an opening provided in the fuel exchange jig, A refueling jig for a boiling water reactor, characterized in that the movement of the first stopper in the horizontal direction is restrained with respect to two stoppers. In the boiling water reactor fuel change jig according to claim 1,
The second stopper is provided at a predetermined corner closest to the tip of the predetermined blade among the six corners above the predetermined fuel assembly. Refueling jig. In the boiling water reactor fuel change jig according to claim 1 or 2,
A boiling water nuclear reactor comprising a plate-like member having a first opening for inserting the first stopper and a second opening for inserting the second stopper Refueling jig. In the boiling water nuclear reactor fuel change jig according to claim 3,
A boiling water reactor fuel exchange jig, wherein the first opening and the second opening are integrally formed. In the boiling water reactor fuel change jig according to claim 1 or 2,
A refueling jig for a boiling water reactor, which is a U-shaped plate member sandwiching the first stopper and the second stopper. In the boiling water reactor fuel change jig according to claim 1 or 2,
It is a rod-like member that is bent so as to be fitted into a first groove provided on the upper end surface of the first stopper and a second groove provided on the upper end surface of the second stopper. Refueling jig for boiling water reactors. In a method for refueling a boiling water reactor comprising a densely arranged hexagonal fuel assembly and a Y-shaped control rod inserted between three fuel assemblies adjacent to each other,
A fuel replacement jig according to any one of claims 1 to 6, wherein the first stopper and the second stopper are engaged through an opening provided in the fuel replacement jig. And the second procedure for exchanging a fuel assembly that is not adjacent to the predetermined wing among the three fuel assemblies is performed by changing the mounting position of the fuel replacement jig. A method for refueling a boiling water nuclear reactor.

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