JP2009145294A - Method and system for fuel assembly arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and system for a fuel assembly arrangement which can create a flexible and accurate fuel arrangement planning. <P>SOLUTION: In the fuel assembly arrangement method, a plurality of fuel assemblies 1 which hold fuel rods in their channel boxes 3 are arranged in a grid pattern in a boiling water reactor core. The fuel assembly 1a has its history that the fuel assembly 1a was arranged in the outer periphery 20 of the reactor core where the channel box is bent by neutrons. The fuel assembly 1a, for which the bending of the channel box is regarded as remaining after the termination of a unit operation cycle, is moved to a position 60, belonging to an area where the channel box is bent in the mode regarded as the same as the bending mode of the channel box for the fuel assembly 1a, where a bending portion of the channel box for the fuel assembly 1a faces the outside of the reactor core. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel assembly arrangement method and a fuel assembly arrangement system for a boiling water reactor.

  A fuel assembly for a boiling water reactor is composed of a plurality of fuel rods, and the plurality of fuel rods are loaded into the reactor while being housed in a rectangular channel box made of Zircaloy. The channel box has the property that, when irradiated with strong energy neutrons (hereinafter, fast neutrons) generated immediately after the nuclear fission of the fuel, the metal crystals grow and extend in the longitudinal direction (vertical direction). .

  By the way, the amount of fast neutrons in the nuclear reactor decreases from the central part of the core toward the outer peripheral part, and in particular, the region from the outermost peripheral part of the core to the third part (hereinafter referred to as the outer peripheral part). In the area, the change is remarkable. Therefore, in the fuel assembly loaded in the outer peripheral region, the elongation of the surface on the central side is relatively larger than the expansion on the outer peripheral surface of the core due to the difference in the amount of fast neutrons, and the channel box is located in the central portion of the core. Bends in a convex shape. When the deformation of the channel box proceeds, the possibility that the channel box interferes with the control rod is improved. In particular, the bending of this channel box tends to increase compared to the conventional case in the background of the prolonged stay of fuel in the core and the prolonged operation cycle of the reactor (about 15 to 24 months). This is an important factor to consider in the fuel assembly layout plan.

  As a technique related to the arrangement of the fuel assemblies in consideration of the bending of the channel box, there has been proposed a method of exchanging positions of fuel assemblies separated by an odd number of units along the diagonal of the unit lattice of the fuel assemblies (Patent Document 1). Etc.).

JP-A-5-264770

  By the way, in an actual fuel arrangement plan, a fuel assembly having a longer residence time in the core tends to maintain the core characteristics by being arranged on the outer peripheral side of the core in the next operation cycle. For this reason, if the above-mentioned technique for exchanging only fuel assemblies located on the diagonal of the unit cell of the fuel assembly is used to satisfy the core characteristics, the constraints that occur when the fuel assembly moves are too severe. There are many scenes that are difficult to apply. In reality, the fuel assemblies arranged inside the outer peripheral region (that is, near the core center) may include those having a history of having been arranged in the outer peripheral region. When the fuel assembly is rearranged in the outer peripheral region, it is necessary to reduce the possibility of interference with the control rod in consideration of the bending mode of the channel box.

  An object of the present invention is to provide a fuel assembly arrangement method and a fuel assembly arrangement system capable of creating a flexible and accurate fuel arrangement plan.

  (1) In order to achieve the above object, the present invention provides a fuel assembly arrangement method in which a plurality of fuel assemblies each containing fuel rods in a channel box are arranged in a lattice pattern in a core of a boiling water reactor. A fuel assembly having a history of being arranged in the outer peripheral region of the core where the channel box is bent by the channel box, and the bending of the channel box is considered to remain after the end of the unit operation cycle. It is assumed that the position where the channel box belongs to a region where the channel box is bent in a manner that can be regarded as the same as the bending manner, and the bent portion of the channel box of the fuel assembly moves to a position facing the outside of the core.

  By moving the fuel assembly in this way, it is possible to select a movement candidate site corresponding to the bending state of the channel box, and to select more positions as conventional movement candidate sites for relaxing the bending of the channel box. Therefore, a flexible and accurate fuel arrangement can be created.

  (2) In the above (1), preferably, when the fuel assembly has a history of being arranged in the outer peripheral region for an odd number of cycles, the bending of the channel box of the fuel assembly is the unit operation cycle. It shall be regarded as remaining after the end.

  (3) In the above (1), preferably, the region where the channel box is bent in a mode that can be regarded as the same as the bending mode of the channel box of the fuel assembly is divided into a plurality of the outer peripheral regions based on the bending mode of the channel box. Among the classified regions, the region to which the fuel assembly belongs in the history closest to the history arranged in the outer peripheral region is used.

  (4) In the above (3), preferably, the outer peripheral region includes an oblique region in which the fuel assembly is disposed such that a corner portion of the channel box faces a center portion of the core, and the channel box It is classified into two regions, that is, a straight region in which the fuel assembly is disposed so that a flat surface portion faces the central portion of the core.

  (5) In the above (4), preferably, the oblique region is a region corresponding to two layers from the outermost periphery of the core toward the center, and the straight region is centered from the outermost periphery of the core. It is assumed that it is a region for three layers toward the part.

  (6) In order to achieve the above object, the present invention provides a fuel assembly arrangement method in which a plurality of fuel assemblies in which fuel rods are housed in a channel box are arranged in a lattice pattern in the core of a boiling water reactor. Two fuel assemblies having a history of being arranged in an outer peripheral region of the core where the channel box is bent, and the bending of the channel box is considered to remain after the end of the unit operation cycle, It can be considered that the channel box is bent in the same manner after the completion, and when the positions of the channel boxes are exchanged, the positions of the two fuel assemblies in which the bent portions of the respective channel boxes face the outside of the core together. Shall be replaced.

  (7) Further, in order to achieve the above object, the present invention provides a fuel assembly arrangement system in which a plurality of fuel assemblies in which fuel rods are housed in a channel box are arranged in a lattice pattern in the core of a boiling water reactor. Bending region data indicating the outer peripheral region of the core where the channel box is bent by neutrons, bending classification data in which the core is classified into a plurality of regions based on the bending state of the channel box after the end of the unit operation cycle, and the channel box A core information storage device having moving region data indicating a region in the core in which the fuel assemblies can be arranged such that a bent portion of the fuel assemblies faces the outside of the core, and past and present arrangement positions of the plurality of fuel assemblies The arrangement position history data that is the history data and the bending that is the history data of the past and current bending modes of the plurality of fuel assemblies A fuel assembly information storage device having history data, a display device for displaying a fuel assembly to be moved when starting the next operation cycle from among the plurality of fuel assemblies, and a display device displayed on the display device An input device for an operator to select one that moves from a plurality of fuel assemblies; and a control device that calculates a candidate location for movement of the fuel assembly selected via the input device, the control The apparatus refers to the arrangement history data and the bending history data of the selected fuel assembly, and has a history that the selected fuel assembly is arranged in the outer peripheral region, and the selected fuel assembly When the bending of the body channel box can be regarded as remaining after the end of the unit operation cycle, referring to the arrangement history data of the selected fuel assembly, A first process for identifying a region to which the fuel assembly belongs in the most recent history based on the bending classification data, and the selected fuel assembly with reference to the bending history data of the selected fuel assembly. A region that is specified by the first and second processing, and performs a second process for specifying a region where the bent portion of the channel box of the assembly can be arranged so as to face the outside of the core based on the moving region data. The positions included in both are displayed on the display device as candidate locations for movement of the selected fuel assembly.

  According to the present invention, since a flexible and accurate fuel assembly arrangement plan can be created, it is possible to reduce the effort required for evaluating the interference between the channel box and the control rod.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view of a boiling water reactor according to an embodiment of the present invention.

  In the core of the boiling water reactor shown in this figure, a plurality of fuel assemblies 1 are arranged in a lattice so as to form an octagon centered on the central portion O of the core. The fuel assemblies 1 arranged in a grid form constitute a unit cell 10 (see FIG. 2) with four fuel assemblies 1 arranged in a square shape. A cross-shaped control rod 2 is arranged at the center of the unit cell 10.

  FIG. 2 is an enlarged view of the fuel assembly per unit cell in FIG. In addition, the same code | symbol is attached | subjected to the same part as the previous figure, and description is abbreviate | omitted (the following figure is the same).

  The fuel assembly 1 shown in FIG. 2 includes a channel box 3 and a channel fastener 4.

  The channel box 3 is a tube formed by forming a Zircaloy plate into a square shape, and a plurality of fuel rods (not shown) are accommodated therein. Since the channel box 3 is made of metal, it has a property of extending in the longitudinal direction (vertical direction) in proportion to the amount of fast neutrons to be irradiated. A spacer 5 is attached to the surface of the channel box 3 on the control rod 2 side. The spacer 5 is for forming a gap with the channel box 3 (fuel assembly 1) arranged opposite to each other, and the control rod 2 is arranged in the gap formed by the spacer 5. .

  The channel fastener 4 holds a gap between the four fuel assemblies 1 constituting the unit cell 10, and each fuel assembly 1 is positioned at the center of the unit cell 10 (that is, the position of the control rod 2). It is attached to the corner. Since the channel fastener 4 is provided on the control rod 2 side together with the spacer 5, the channel fastener 4 also functions to determine the arrangement direction of each fuel assembly 1 with respect to the control rod 2.

  FIG. 3 is a schematic view of the fuel assembly arrangement system according to the embodiment of the present invention.

  The fuel assembly arrangement system (hereinafter referred to as “fuel arrangement system” as appropriate) shown in this figure is used when the fuel assemblies 1 loaded in the core are relocated when the unit operation cycle is completed. A fuel arrangement control device 80, a core information storage device 81, a fuel information storage device 82, an input device (keyboard 83a, mouse 83b, etc.) 83, a display device (color CRT, etc.) 84, and a printing device (Printer) 85 and a core characteristic analyzer 86 are provided.

  A fuel arrangement control device (hereinafter referred to as “control device” as appropriate) 80 is a fuel selected by the operator via the input device 83 based on information stored in the core information storage device 81 and the fuel information storage device 82. The movement candidate site in consideration of the bending of the channel box 3 of the aggregate 1 is displayed on the display device 84.

  The control device 80 includes a print control unit 81 a that controls the printing device 85, a display control unit 81 b that controls the display device 84, and an external storage unit in which programs used for rearrangement of the fuel assembly 1 are recorded. 81c, a main storage unit 81d in which data used by the control device 80 is temporarily recorded, an arithmetic processing unit 81e in which various arithmetic processes are performed, and a process input unit 81f in which processes from the input device 83 are input It has.

  The core information storage device 81 records information related to the core, and includes bending region data 91, bending classification data 92, and moving region data 93.

  The bending region data 91 is data indicating a region where bending due to fast neutrons occurs in the channel box 3 after the end of the unit operation cycle. FIG. 4 is a diagram showing the cores classified according to the bending region data 91.

  As shown in this figure, the bent region data 91 classifies the inside of the core into an outer peripheral region 20 located over several outer peripheral layers of the core and an inner region 21 located inside the outer peripheral region 20.

  The outer peripheral region 20 is a portion where the amount of fast neutrons generated along with fission decreases rapidly. By the way, in the core, the amount of fast neutrons tends to decrease in proportion to the distance from the central portion O. This tendency becomes particularly prominent in the vicinity of the outer peripheral portion, and the amount of fast neutrons rapidly decreases in the region from the outer peripheral portion to the central portion O up to several layers as compared with the vicinity of the center. That is, this region is the outer peripheral region 20. In the fuel assembly 1 loaded in the outer peripheral region 20, the elongation of the surface on the center side becomes relatively larger than the elongation of the surface on the outer peripheral side of the core of the channel box 3 due to the difference in the amount of fast neutrons to be irradiated. The channel box 3 is deformed in a convex shape toward the center O.

  In the present embodiment, in the region where the fuel assembly 1 is arranged so that the flat portion of the channel box 3 faces the center portion O, three layers from the outer periphery are provided, and the corner portion of the channel box 3 is the center portion O. In the region arranged so as to face the two, two layers from the outer periphery are defined as the outer peripheral region. The reason for the latter being two layers is to make the distance from the center O the same as the former. That is, since the channel box 3 is arranged in the diagonal direction in the latter region, it corresponds to √2 times the width of the former region, and if the latter is set to two layers, the distance from the center O is This is because it becomes the same level.

  The bending classification data 92 is data obtained by classifying the outer peripheral region 20 into a plurality of regions based on the bending mode (the bending portion, the direction, the amount, and the like) of the channel box 3 after the end of the unit operation cycle. Based on the bending classification data 92, the fuel assemblies 1 belonging to the same region can be regarded as having the same bending state of the channel boxes 3.

  FIG. 5 is a diagram showing the outer peripheral area 20 classified by the bending classification data 92.

  As shown in this figure, the bending classification data 92 of the present embodiment classifies the outer peripheral area 20 into two areas, a straight area 20A and an oblique area 20B. In FIG. 5, the straight region 20 </ b> A is a region where the fuel assembly 1 is disposed such that the flat portion 31 of the channel box 3 faces the center portion O of the core, and the outer periphery when the outer peripheral region 20 is defined above. This corresponds to a region having a width corresponding to three layers from the center toward the center. The oblique region 20B is a region where the fuel assembly 1 is disposed so that the corner portion 32 of the channel box 3 faces the central portion O of the core. From the outer periphery when the outer peripheral region 20 is defined in the above, from the outer periphery to the central portion. This corresponds to a region having a width corresponding to two layers.

  FIG. 6 is an explanatory view of the bending mode of the channel box 3 in the straight region 20A and the oblique region 20B.

  The channel box 3A of the fuel assembly shown in FIG. 6A is arranged in the straight region 20A, and includes a flat part 31a arranged on the center O side of the core and a flat part 31b arranged on the outer peripheral side. have. In the channel box 3A shown in this figure, there is a deviation in the amount of fast neutrons irradiated to the flat surface portion 31a and the flat surface portion 31b. Therefore, the channel box 3A has a mode in which the flat surface portion 31a protrudes convexly toward the central portion O. Bend at.

  The channel box 3B of the fuel assembly shown in FIG. 6B is disposed in the oblique region 20B, and includes a corner portion 32a disposed on the center portion O side of the core and a corner portion 32b disposed on the outer peripheral side. have. In the channel box 3B shown in this figure, there is a deviation in the amount of fast neutrons irradiated to the corners 32a and 32b. Therefore, the channel box 3B has a mode in which the corners 32a protrude in a convex shape toward the center O. Bend at.

  In the present embodiment, in order to simplify the processing, the outer peripheral region 20 is divided into two regions, a straight region 20A and a diagonal region 20B, and the bending mode of the channel box 3 is classified into two. Needless to say, 20 may be further divided to further subdivide the bending mode of the channel box 3. Further, the bent shape of the channel box 3 of each fuel assembly 1 may be monitored, and control may be performed so as to replace those having similar bent shapes.

  The moving area data 93 is an area where the fuel assembly 1 can be arranged so that the bent portion (bent portion) of the channel box 3 faces the outside of the core when there is the fuel assembly 1 in which the channel box 3 is bent. This is data indicating (movable area). The movement region data 93 is determined based on the relationship between the position of the channel fastener 4 of the fuel assembly 1 and the bending mode of the channel box 3, and is different for each fuel assembly 1.

  FIG. 7 is a diagram showing the cores classified by the moving area data 93. In the core shown in this figure, a fuel assembly 1A is arranged, and an example of a movable region 55 with respect to this fuel assembly 1A is indicated by hatching. FIG. 8 is an enlarged view of the vicinity of the fuel assembly 1A in FIG.

  The fuel assembly 1A is disposed in the straight region 20A after the end of the unit operation cycle, and the channel box 3 has a bent portion 35 with a flat surface portion protruding toward the central portion O. The channel fastener 45 of the fuel assembly 1A is located at the lower left in FIG. 7 and faces the portion where the control rod 2 is inserted.

  The movable region 55 indicates a position where the fuel assembly 1A can be moved so that the bent portion 35 faces the outside of the core. The movable region 55 is determined based on the position of the channel fastener 45 and the position of the bent portion 35 of the fuel assembly 1A. That is, the fuel assembly 1 needs to be loaded at a position where the channel fastener 4 faces the control rod 2 because of the arrangement of the fuel rods, but the bent portion of the channel box 3 faces the outer periphery at the position after the movement. If it tries to do so, the loading position of the fuel assembly 1 is generally limited. Therefore, if the position of the channel fastener 4 of each fuel assembly 1 and the position of the bent portion (bending mode) are known, the movable region of each fuel assembly 1 can be determined. Note that the position of the bent portion of each fuel assembly 1 can be obtained from the bending history data 95 described later. Note that the position information of the channel fastener 4 or the fuel rod arrangement data of each fuel assembly 1 is stored in the fuel information storage device 82.

  By the way, in the present embodiment, the movement destination of the fuel assembly 1 for correcting the bending of the channel box 3 is (1) in a mode that can be regarded as the same as the bending mode of the channel box 3 of the fuel assembly 1 at the time of movement. The position where the channel box 3 belongs to the bent region and (2) the position where the bent portion of the channel box 3 faces the outside of the core is selected. When the fuel assembly 1 is moved to a position satisfying such conditions, the bending of the channel box 3 can be relaxed as described below.

  FIG. 9 is a diagram of a moving procedure for relaxing the bending of the channel box 3 after the end of the unit operation cycle. In this figure, the channel box 3 indicated by the broken line is the one before the movement, and the one indicated by the solid line is the one after the movement.

  The fuel assembly shown in FIG. 9A is disposed in the straight region 20A. The channel box 3A of the fuel assembly shown in this figure belongs to the straight region 20A after the end of the unit operation cycle, and the bent portion of the channel box 3 is moved to a position facing the outside of the core.

  Here, since the direct area 20A of the movement destination is the same as the area where the fuel assembly 1 is located before the movement, the bending manner of the channel box 3 at the positions before and after the movement can be regarded as the same. In addition, when the fuel assembly 1 is moved, the fuel assembly 1 is rotated 180 degrees so that the bent portion of the channel box 3 faces the outside of the core. Can be directed to the center O side of the core. Therefore, when the fuel assembly 1 is moved to such a position, the portion opposite to the bent portion in the previous operation cycle can be disposed on the center portion O side of the core, so that the channel box 3A is bent in the next operation cycle. Can be relaxed.

  The channel box 3B of the fuel assembly shown in FIG. 9B is disposed in the oblique region 20B. The channel box 3B shown in this figure belongs to the oblique region 20B after the end of the unit operation cycle, and the bent portion of the channel box 3B is moved to a position facing the outside of the core. Also in this case, as in the case of FIG. 9 (a), the portion opposite to the bent portion in the previous operation cycle can be arranged on the center O side of the core, so that the channel box 3B is bent in the next operation cycle. Can be relaxed.

  Furthermore, in the present embodiment, in order to simplify the processing, the fuel assembly 1 having a history arranged in the outer peripheral region 20 for an even number of cycles is bent in the channel box 3 by the bending relaxation processing shown in FIG. It is considered that it was corrected. When handled in this way, the following operation sequence can be adopted.

  FIG. 10 is a diagram showing an operation sequence when the bending relaxation processing of the channel box 3 is performed on the fuel assembly.

  FIG. 10A shows an operation sequence of the fuel assembly 1 having a history arranged in the outer peripheral region 20 for an even number of cycles. The fuel assembly having this history can be considered that the bend generated in the channel box 3 has been corrected by the bend relaxation processing shown in FIG. 9, so that the bend of the channel box 3 is not considered in the next operation cycle. It can arrange | position to the area | region 20 (S201). However, if it is arranged in the outer peripheral region 20 in the next operation cycle (S202), it will have a history of being arranged in the outer peripheral region 20 for an odd number of cycles in total, so that the bending of the channel box 3 will occur again, In the operation cycle, it is necessary to examine the arrangement position in consideration of the bending of the channel box 3 (S203). In the subsequent operation cycle, the above operation sequence is repeated.

  FIG. 10B is an operation sequence of the fuel assembly 1 having a history arranged in the outer peripheral region 20 for an odd number of cycles. Since the fuel assembly having this history can be considered to be bent in the channel box 3, the channel box 3 is used when the fuel assembly 1 is disposed in the outer peripheral region 20 in the next operation cycle. It is necessary to consider the arrangement position in consideration of the direction of (S211). However, if it is arranged in the outer peripheral region 20 in the next operation cycle (S212), it will have a history of being arranged in the outer peripheral region 20 for an even number of cycles in total, so the bending of the channel box 3 is considered in the next operation cycle. (S213). Thereafter, the above cycle is repeated as in FIG.

  In FIG. 3, the fuel information storage device 82 records information relating to the fuel assembly 1, and has arrangement history data 95 and bending history data 96.

  The arrangement history data 95 is data on the history of past and current arrangement positions of the fuel assemblies 1 in the core. The control device 80 determines whether or not the fuel assembly 1 selected by the operator has a history of being arranged in the outer peripheral region 20 by combining the arrangement history data 95 with the bent region data 91, and considers bending. Determine whether the placement should be considered. Further, the arrangement history data 95 is used for estimation of the bending mode of the channel box 3 by combining with the bending classification data 92, or by combining with the movement area data 93, the arrangement history data 95 of the fuel movement candidate site selected in the fuel arrangement plan. It is used for selection.

  The bending history data 96 is history data of past and current bending modes of each fuel assembly 1. The bending history data of the channel box 3 of each fuel assembly 1 is arranged at the position when it has been arranged in the outer peripheral region 20 in the past, and how the bending of the channel box 3 has changed at that position. Accumulated by asking for each. Based on the bending history data 96, the control device 80 determines whether or not the bending remains in the channel box 3 of the selected fuel assembly 1, and determines whether or not the arrangement considering the bending should be considered. . The bending history data 96 is used when deriving the movement area data 93 by combining with the fuel rod arrangement information of each fuel assembly 1 (that is, the position information of the channel fastener 4).

  The input device 83 inputs operation information from the operator to the control device 80. For example, the keyboard 83a and the mouse 83b correspond to this. The operator selects, via the input device 83, the fuel assembly displayed on the display device 84 to examine the arrangement plan. The display device 84 is a portion where a processing result by the control device 80 is displayed. The operator gives a command to the control device 80 via the input device 83 while watching the processing result displayed on the display device 84. The printing device 85 prints an arrangement plan prepared using the fuel arrangement system into a document.

  The core characteristic analysis device 86 analyzes the core characteristics of the fuel arrangement plan drafted using the control device 80, and whether or not the drafted arrangement plan draft satisfies the core characteristics required in the next operation cycle. Used to evaluate Here, the core characteristics indicate the reactivity characteristics and thermal characteristics of the core. The reactivity characteristic is mainly used when evaluating whether or not a nuclear reactor can maintain a predetermined heat output, and the thermal characteristic is mainly the distribution of heat generation by fuel. It is used for evaluation, and is used to prevent fuel damage by avoiding local heat generation.

  Next, a fuel assembly placement method using the fuel placement system according to the present embodiment will be described.

  FIG. 11 is a flowchart of fuel rearrangement by the fuel arrangement system according to the present embodiment.

  In the fuel arrangement system configured as described above, when the unit operation cycle ends, the fuel assembly 1 whose arrangement position is to be changed when starting the next operation cycle is displayed on the display device 84 (S101). At this time, if there is fuel to be taken out from the core, the position of the fuel may be left blank to improve work efficiency.

  The operator selects an arbitrary fuel assembly 1 from the fuel assembly 1 displayed on the display device 84 via the input device 83 (S102). The control device 80 examines the arrangement history data 95 of the fuel assembly 1 selected by the operator, and the fuel assembly is arranged in the area defined by the bending area data 91 (the outer peripheral area 20 in the present embodiment). It is determined whether there is a history (S103).

  When the selected fuel assembly 1 has a history of being arranged in the outer peripheral region 20, the control device 80 examines the bending history data 96 of the fuel assembly 1 and the channel box 3 of the fuel assembly 1. It is determined whether or not the bending remains (S104).

  In this determination, when the selected fuel assembly 1 has a history of being arranged in the outer peripheral region 20 for an odd number of cycles, the channel box 3 is bent based on the operation sequence shown in FIG. The process may proceed to the next step (S105) assuming that it remains. This is because the bent to the channel box 3 (including the case where the bending of the channel box 3 is once relaxed) when it is arranged in the outer peripheral region 20 for an odd number of cycles (mainly one cycle or three cycles). This is because it is necessary to perform the bending relaxation treatment. Thus, if it is determined whether or not the bend remains in the channel box 3, the processing load on the control device 80 can be reduced, so that the processing efficiency can be improved. In order to check the number of operation cycles in which the selected fuel assembly 1 has been arranged in the outer peripheral region 20 in the past, for example, the bent region data 91 and the arrangement history data 95 may be used.

  If it is determined that the bend remains in the channel box 3 of the selected fuel assembly 1, a movement candidate site is selected based on the position of the selected fuel assembly 1, the bend mode of the channel box 3, and the like. The process proceeds to (S105).

In this step, the control device 80 refers to the arrangement history data 95 of the selected fuel assembly 1 and determines the region to which the fuel assembly 1 belonged in the history closest to the history arranged in the outer peripheral region 20. Ask. Then, the region to which the fuel assembly 1 belongs is specified based on the bending classification data 92, and the specified region is limited as a candidate movement location for the fuel assembly 1 (first limiting process). That is, when the channel box 3 of the selected fuel assembly 1 is arranged in the immediate region 20A in the latest history of being arranged in the outer peripheral region 20, the channel box 3 is considered to have the same bending mode. The movement candidate sites are limited within the straight area 20A where the movement can be performed. When determining the movement destination of the selected fuel assembly 1, the bending mode of the channel box 3 of the selected fuel assembly 1 is checked using the bending history data 96, and the same as the bending mode. An area where the channel box 3 bends in a manner that can be regarded as being obtained may be obtained using the bend classification data 92, and the area may be limited as a movement candidate place.

  Further, the control device 80 refers to the bending history 96 data of the selected fuel assembly to check the position of the bent portion (bent portion) of the channel box 3 of the fuel assembly 1, and the bent portion is the core. An area (movement area data 93) that can be arranged so as to face the outside is limited as a movement candidate place (second limitation process). That is, when the selected fuel assembly 1A in FIG. 7 and FIG. 8 is selected, the movement candidate site is limited to the position hatched in FIG. When obtaining the movement area data 93, for example, the position of the bent portion may be obtained based on the bending mode of the channel box 3 of the fuel assembly 1 obtained from the arrangement history data 95 and the bent classification data 92. .

  As a result of such processing, the positions included in both of the areas limited by the first limiting process and the second limiting process are displayed on the display device 84 as the movement candidate sites of the selected fuel assembly 1 ( S106). When the fuel assembly 1 is moved to the position displayed on the display device 84, the portion opposite to the bent portion during the completed operation cycle can be arranged on the central portion O side. Bending can be relaxed.

  FIG. 12 is a display example of the movement candidate sites of the selected fuel assembly 1a. FIG. 12A is a diagram showing a part of the movement candidate sites displayed on the display device 84 when the fuel assembly 1a located in the direct region 20A is selected. FIG. 12B is a diagram showing a part of the movement candidate site displayed when the fuel assembly 1a located in the oblique region 20B is selected. In these drawings, the hatched portion is the selected fuel assembly 1a, the highlighted one is the movement candidate site 60, and the arrangement position where the black one is excluded from the candidates. 61.

  When the movement candidate site of the selected fuel assembly 1a is displayed on the display device 84, the operator selects one of the displayed movement destination positions via the input device 83 (S107). Thereby, the movement plan of the selected fuel assembly 1 is completed. In addition, when the fuel assembly 1 whose arrangement position is to be changed exists at the destination position, a plan for exchanging both positions may be made. At this time, it is preferable that the control device 80 displays a message or the like for confirming the fact to the operator so as to obtain the confirmation of the operator. If there is a fuel assembly 1 to be relocated at the selected destination, the selected fuel assembly 1 is also displayed when the process of S105 is performed on the fuel assembly 1. Needless to say, there is no problem in exchanging the positions.

  Here, the process returns to S103. In S103, when the selected fuel assembly 1 has no history of being arranged in the outer peripheral region 20 (that is, the fuel assembly 1 loaded in the core for the first time, or the history of being loaded only in the inner region 21) ), Since it is not necessary to consider the bending of the channel box 3 for the fuel assembly 1, the position excluding the restriction resulting from the bending of the channel box 3 is displayed on the display device 84 as a candidate movement location (S108). ). In S104, it is not necessary to consider the bending of the channel box 3 of the fuel assembly 1 even when it is considered that the bending does not remain in the selected fuel assembly 1. Therefore, the bending of the channel box 3 is not considered. The position excluding the constraints resulting from is displayed as a candidate movement location (S108). In these cases, it goes without saying that restrictions may be applied to the candidate movement sites based on other restrictions. When the movement candidate site is displayed on the display device 84 in S108, the operator selects a desired position from the area and completes the movement plan (S107).

  When the processing from S101 to S107 as described above is repeated and the creation of the arrangement plan of the fuel assembly 1 whose arrangement position is to be changed is completed, the plan is recorded in the fuel information storage device 82 or printed by the printing device 85. Save the created plan.

  13 and 14 show an example of the result of creating the fuel assembly arrangement plan. FIG. 13 shows an arrangement plan of the fuel assemblies located in the direct region 20A. For example, there are those shown in FIG. 13 (a) and those shown in FIG. 13 (b). In the example shown in FIG. 13, the fuel assembly 1 on the outermost peripheral side of the core is not moved, but this is generally because the fuel assembly 1 arranged on the outermost periphery has a long loading time and is therefore output. This is because it is difficult to move to the inside of the reactor core because the channel box 3 is small or the bending amount of the channel box 3 is large. In the combustion assembly 1 arranged on the outermost periphery, the bent surface of the channel box 3 is not the same in two consecutive operation cycles so that the bent channel box 3 does not interfere with the control rod 2. It is preferable to move while rotating 90 degrees. FIG. 14 shows an arrangement plan of the fuel assemblies located in the oblique region 20B. According to the arrangement plan created in this way, the bending of the channel box 3 can be easily relaxed, so that the number of channel boxes 3 to be subject to interference evaluation with the control rod 2 can be reduced.

  Next, the effect of this embodiment will be described.

  In general, when the reactor operation cycle is prolonged, the problem of the bending of the channel box of the fuel assembly arranged in the outer peripheral region of the core becomes more prominent. Therefore, in order to prevent the interference between the channel box and the control rod, It is important to control the bending of the channel box. As a technique related to the arrangement of fuel assemblies for controlling the bending of the channel box, a method of exchanging positions of fuel assemblies separated by an odd number of units along the diagonal of the unit lattice of the fuel assemblies has been proposed ( (See Patent Document 1).

  However, if the fuel assemblies separated by an odd number of units along the diagonal line are subject to replacement as in this technology, the restrictions associated with the movement of the fuel assemblies are too strict, making it difficult to apply in actual operation. Also occurs. In addition, in the above technique, since the history of the bent state of the channel box of each fuel assembly is not taken into consideration, it may be considered that even if the position is moved, the bending of the channel box is not relaxed.

  On the other hand, the fuel arrangement system according to the present embodiment has a history of arrangement in the outer peripheral region 20, and the fuel assembly 1 in which the bending of the channel box 3 is considered to remain after the end of the unit operation cycle. Is a position belonging to a region where the channel box 3 bends in a manner that can be regarded as being the same as the bending manner of the channel box 3 of the fuel assembly 1, and the bent portion of the channel box 3 of the fuel assembly 1 It has moved to a position facing outward.

  According to such a fuel assembly arrangement method, it is a movement candidate site in consideration of the bending history of the channel box 3 of the fuel assembly 1 selected by the operator, and is suitable for the bending mode of the fuel assembly 1. However, since it is selected, the bending of the channel box 3 of the selected fuel assembly 1 can be relaxed accurately. As a result, the channel box of the fuel assembly 1 is bent even when a fuel having a history of being placed in the outer peripheral region 20 in the past is rearranged in the outer peripheral region 20, although it is currently placed in the inner region 21. A location that can alleviate this can be selected as a candidate site.

  Further, according to this fuel assembly arrangement method, not only the position of the unit lattice of the fuel assembly 1 on the diagonal line but also other locations that satisfy the conditions for relaxing the bending of the channel box 3 Since it can be listed as a movement candidate site, a more flexible arrangement plan can be created, and an arrangement plan in accordance with the actual situation can be made.

  As described above, according to the present embodiment, it is possible to select a movement candidate site according to the bending mode of the channel box 3, and more movement candidate sites for relaxing the bending of the channel box 3 than in the past. Since a position can be selected, a flexible and accurate fuel arrangement can be created. As a result, the bending of the channel box 3 can be alleviated each time the operation cycle is completed, so that the number of fuel assemblies 1 that are subject to interference evaluation between the channel box 3 and the control rod 2 can be reduced. Therefore, according to the present embodiment, it is possible to reduce the labor and time required for the fuel arrangement planning, and thus it is possible to improve the use efficiency and economics of the nuclear power plant.

1 is a plan view of a boiling water reactor according to an embodiment of the present invention. The enlarged view of the fuel assembly per unit cell in FIG. 1 is a schematic view of a fuel assembly arrangement system according to an embodiment of the present invention. The figure which shows the core classified according to the bending | flexion area | region data 91. FIG. The figure which shows the outer periphery area | region 20 classified by the bending classification data 92. FIG. Explanatory drawing of the bending aspect of the channel box 3 in the direct area | region 20A and the diagonal area | region 20B. The figure which shows the core classified by the movement area data 93. FIG. FIG. 8 is an enlarged view near the fuel assembly 1 </ b> A in FIG. 7. The figure of the movement procedure for relieving the bending of the channel box 3 after completion | finish of a unit driving cycle. The figure which shows the operation | movement sequence at the time of implementing the bending relaxation process of the channel box 3 with respect to a fuel assembly. The flowchart of the fuel rearrangement by the fuel arrangement system which concerns on this Embodiment. The example of a display of the movement candidate site of the selected fuel assembly 1a. An example of the preparation result of the arrangement plan of the fuel assembly located in the direct region 20A. An example of the creation result of the arrangement plan of the fuel assembly located in the oblique region 20B.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel assembly 2 Control rod 3 Channel box 4 Channel fastener 20 Outer periphery area | region 20A Direct area | region 20B Diagonal area | region 21 Internal area | region 60 Movement candidate place 80 Fuel arrangement | positioning control apparatus (control apparatus)
81 Core information storage device 82 Fuel information storage device 83 Input device 84 Display device 91 Bending region data 92 Bending classification data 93 Moving region data 95 Arrangement history data 96 Bending history data

Claims (7)

In a fuel assembly arrangement method of arranging a plurality of fuel assemblies containing fuel rods in a channel box in a lattice form in the core of a boiling water reactor,
A fuel assembly having a history of being arranged in an outer peripheral region of the core where the channel box is bent by neutrons and in which the bending of the channel box is regarded as remaining after the end of the unit operation cycle is obtained. The fuel cell is a position belonging to a region where the channel box bends in a manner that can be regarded as the same as that of the fuel cell, and the bent portion of the channel box of the fuel assembly moves to a position facing the outside of the core. Aggregate placement method. The fuel assembly arrangement method according to claim 1, wherein
When the fuel assembly has a history arranged in the outer peripheral region for an odd number of cycles,
The fuel assembly arrangement method, wherein the fuel assembly channel box bends after the end of the unit operation cycle. The fuel assembly arrangement method according to claim 1, wherein
The region where the channel box bends in a mode that can be regarded as the same as the bend mode of the channel box of the fuel assembly,
Of the regions classified into a plurality of the outer peripheral regions based on the bending mode of the channel box, the fuel is a region to which the fuel assembly belongs in the history closest to the history arranged in the outer peripheral region. Aggregate placement method. The fuel assembly arrangement method according to claim 3, wherein
The outer peripheral region includes an oblique region where the fuel assembly is disposed such that a corner portion of the channel box faces the center portion of the core, and a flat portion of the channel box faces the center portion of the core. The fuel assembly arrangement method is characterized in that the fuel assembly is classified into two regions, ie, a direct region where the fuel assembly is disposed. The fuel assembly arrangement method according to claim 4, wherein
The oblique region is a region corresponding to two layers from the outermost peripheral portion of the core toward the central portion,
The direct region is a region corresponding to three layers from the outermost peripheral portion of the core toward the central portion, and the fuel assembly arranging method according to claim 1. In a fuel assembly arrangement method of arranging a plurality of fuel assemblies containing fuel rods in a channel box in a lattice form in the core of a boiling water reactor,
Two fuel assemblies having a history arranged in an outer peripheral region of the core where the channel box is bent by neutrons, and the bending of the channel box is considered to remain after the end of the unit operation cycle,
It can be considered that the bending manner of the channel box after the end of the unit operation cycle is the same, and two fuel assemblies in which the bent portions of the respective channel boxes face the outside of the core when the positions thereof are exchanged. A fuel assembly arrangement method characterized by exchanging positions of bodies. In a fuel assembly arrangement system in which a plurality of fuel assemblies containing fuel rods in a channel box are arranged in a lattice pattern in the core of a boiling water reactor,
Bending region data indicating the outer peripheral region of the core where the channel box is bent by neutrons, bending classification data in which the inside of the core is classified into a plurality of regions based on the bending state of the channel box after the end of the unit operation cycle, and the channel box A core information storage device having moving region data indicating a region in the core in which the fuel assembly can be arranged so that a bent portion of the core faces the outside of the core;
A fuel assembly having arrangement position history data that is history data of past and current arrangement positions of the plurality of fuel assemblies, and bending history data that is history data of past and current bending modes of the plurality of fuel assemblies. A body information storage device;
A display device for displaying a fuel assembly to be moved when starting a next operation cycle from the plurality of fuel assemblies;
An input device for an operator to select one that moves from a plurality of fuel assemblies displayed on the display device;
A controller for calculating a candidate location for movement of the fuel assembly selected via the input device,
The controller is
With reference to the arrangement history data and the bending history data of the selected fuel assembly, the selected fuel assembly has a history of being arranged in the outer peripheral region, and the channel of the selected fuel assembly When it can be considered that the box bending remains after the end of the unit operation cycle,
Referring to the arrangement history data of the selected fuel assembly, a region to which the fuel assembly belonged in a history nearest to the history arranged in the outer peripheral region is specified based on the bending classification data. 1 treatment,
With reference to the bending history data of the selected fuel assembly, a region where the bent portion of the channel box of the selected fuel assembly can be arranged to face the outside of the core is based on the moving region data. Perform the second process to identify,
The fuel assembly arrangement system, wherein a position included in both of the areas specified by the first and second processes is displayed on the display device as a candidate location for movement of the selected fuel assembly.

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