Analysis method, program, and analysis device

Abstract

To properly evaluate a fuel assembly whose operation time is scheduled to extend before operation.SOLUTION: An analysis method comprises the steps of: acquiring a measurement value of a bending amount of a fuel assembly operated by the time length of a first period; calculating a prediction value of a bending coefficient indicating an influence degree to an output due to the bending amount at each timing by the elapse of a second period of the fuel assembly operated by the time length of the second period longer than the first period on the basis of the measurement value of the bending amount; and evaluating the fuel assembly operated by the time length of the second period on the basis of the prediction value of the bending coefficient.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to an analysis method, a program, and an analysis apparatus.

Background Art

[0002] Techniques for evaluating the characteristics of a nuclear reactor are known. For example, Patent Document 1 describes calculating a heat flux thermal hydraulic coefficient including uncertainty due to the amount of bend for a plurality of bent patterns perturbed based on the probability distribution of the amount of bend of a fuel assembly.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, it has been considered to extend the operation time per cycle of a fuel assembly, and it is required to appropriately evaluate a fuel assembly whose operation time is planned to be extended before operation.

[0005] The present disclosure solves the above-described problems, and an object thereof is to provide an analysis method, a program, and an analysis apparatus capable of appropriately evaluating a fuel assembly whose operation time is planned to be extended before operation.

Means for Solving the Problems

[0006] The analysis method according to the present disclosure includes: obtaining a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; based on the measured value of the amount of bending, calculating a predicted value of a bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for a fuel assembly operated for a time length longer than the first period; and evaluating the fuel assembly operated for the time length of the second period based on the predicted value of the bending coefficient.

[0007] The program according to the present disclosure causes a computer to execute: obtaining a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; based on the measured value of the amount of bending, calculating a predicted value of a bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for a fuel assembly operated for a time length longer than the first period; and evaluating the fuel assembly operated for the time length of the second period based on the predicted value of the bending coefficient.

[0008] The analysis device according to the present disclosure includes: a measured value acquisition unit that obtains a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; a predicted value calculation unit that calculates a predicted value of a bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for a fuel assembly operated for a time length longer than the first period based on the measured value of the amount of bending; and an evaluation unit that evaluates the fuel assembly operated for the time length of the second period based on the predicted value of the bending coefficient.

Effect of the Invention

[0009] According to the present disclosure, a fuel assembly whose operation time is planned to be extended can be appropriately evaluated before operation.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited by this embodiment, and when there are a plurality of embodiments, those configured by combining each embodiment are also included.

[0012] (Reactor Core) Figure 1 is an explanatory diagram schematically showing the reactor core to be analyzed, and Figure 2 is a cross-sectional view when the fuel assembly to be analyzed is cut along a plane orthogonal to the axial direction. The analysis device 10 according to the present embodiment is a device for analyzing the core characteristics of a nuclear reactor, and more specifically, a device for evaluating the fuel assembly 6 in the reactor core. As shown in Figure 1, a reactor core 5 that is the object of reactor core design is stored in the nuclear reactor. This reactor core 5 includes a plurality of fuel assemblies 6. Note that the fuel is exchanged in units of the fuel assembly 6.

[0013] (Fuel Assembly and Fuel Rod) Each fuel assembly 6 includes a plurality of fuel rods 29 having fuel pellets 30 and cladding tubes 31 covering the fuel pellets 30, and a grid (not shown) that bundles the cladding tubes 31 of the plurality of fuel rods 29. The inside of the fuel assembly 6 is filled with a moderator (coolant) 33 and is configured such that a plurality of control rods 34 and in-core instrumentation 35 can be inserted. The fuel rods 29 are arranged by aligning a plurality of fuel pellets 30 having a cylindrical shape in the axial direction, and the outside thereof is covered by the cladding tubes 31.

[0014] The fuel assembly 6 is formed in a square cross-sectional shape and is composed of, for example, 17×17 cells 40. Among the 17×17 cells 40, control rods 34 are inserted into 24 cells 40, respectively, and in-core instrumentation 35 is inserted into the cell 40 at the center of the assembly. At this time, the cell 40 into which the control rod 34 is inserted is called a control rod guide tube, and the cell 40 into which the in-core instrumentation 35 is inserted is called an instrumentation guide tube. In addition, fuel rods 29 are inserted into the other cells 40, respectively. When the fuel assembly 6 is used in a boiling water reactor (BWR), the outside of the fuel assembly 6 is covered by a channel box. On the other hand, when the fuel assembly 6 is used in a pressurized water reactor (PWR), the outside of the fuel assembly 6 is open. Then, an inter-assembly gap 32 exists outside the channel box in the case of a BWR and outside the fuel assembly 6 in the case of a PWR.

[0015] (Regarding the bending that occurs in the fuel assembly) FIG. 3 is an explanatory diagram schematically showing a part of a plurality of fuel assemblies. In the following description, the axial direction of the fuel assembly 6 is appropriately referred to as the "Z direction", one direction orthogonal to the axial direction is referred to as the "X direction", and the direction orthogonal to the X direction and the Z direction is referred to as the "Y direction". As shown in FIG. 3, a plurality of fuel assemblies 6 are arranged side by side along the X direction and the Y direction.

[0016] The fuel assembly 6 may bend. At this time, as illustrated in FIG. 3, the fuel assembly 6 bends so as to form concavities and convexities in the X direction or the Y direction. As a result, the gap G between adjacent fuel assemblies 6 may change. When the gap G between the fuel assemblies 6 changes in this way, nuclear fission may be locally promoted and the local output may increase. Therefore, the output of the fuel assembly 6 may be affected by the bend (change in the gap G) occurring in the fuel assembly 6. The analysis device 10 according to the present embodiment evaluates the fuel assembly 6 by calculating a predicted value of the output of the fuel assembly 6 while considering the influence of the bend. As shown in FIG. 3, in the present embodiment, the analysis device 10 performs an evaluation assuming that the bend of the fuel assembly 6 is in the primary mode. However, the present invention is not limited to this, and the analysis device 10 may perform an analysis assuming that the bend of the fuel assembly 6 is in a mode other than the primary mode (for example, the secondary mode or the tertiary mode).

[0017] (Analysis Device) The analysis device 10 calculates the heat flux thermal hydraulic coefficient F, which is a parameter indicating the core characteristics Q and evaluates the fuel assembly 6 based on the heat flux thermal hydraulic coefficient F Q . The heat flux thermal hydraulic coefficient F Q is a parameter indicating the maximum value of the local output in the fuel assembly 6. In the following description, the heat flux thermal hydraulic coefficient F Q will be simply referred to as "coefficient F Q " as appropriate.

[0018] FIG. 4 is a schematic block diagram of the analysis device according to the present embodiment. The analysis device 10 is a device that executes the analysis method according to the present embodiment. As shown in FIG. 4, the analysis device 10 includes an input unit 12, a display unit 14, a storage unit 16, and a control unit 18. Note that the analysis device 10 may be configured as a single device, may be integrally configured with another device, or may be configured as a system combining various devices such as an arithmetic device and a data server, and is not particularly limited.

[0019] The input unit 12 is an input device such as a keyboard, etc., and accepts input of information by the user of the analysis device 10. The display unit 14 is a display device such as a monitor, etc., and displays the analysis result by the analysis device 10. The storage unit 16 is a memory that stores various information such as the calculation content and programs of the control unit 18, and includes, for example, at least one of a main storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and an external storage device such as an HDD (Hard Disk Drive).

[0020] The control unit 18 is an arithmetic unit and includes an arithmetic circuit such as a CPU (Central Processing Unit). The control unit 18 includes a measurement value acquisition unit 20, a prediction value calculation unit 22, a reference coefficient calculation unit 24, and an evaluation unit 26. The control unit 18 reads and executes a program (software) from the storage unit 16 to realize the measurement value acquisition unit 20, the prediction value calculation unit 22, the reference coefficient calculation unit 24, and the evaluation unit 26, and executes the processing. Note that the control unit 18 may execute the processing by one CPU, or may include a plurality of CPUs and execute the processing by these plurality of CPUs. Also, at least a part of the measurement value acquisition unit 20, the prediction value calculation unit 22, the reference coefficient calculation unit 24, and the evaluation unit 26 may be realized by a hardware circuit. Further, the program for the control unit 18 stored in the storage unit 16 may be stored in a recording medium readable by the analysis device 10.

[0021] (Measurement value acquisition unit) The measurement value acquisition unit 20 acquires the measurement value of the amount of bending of the fuel assembly operated for the time length of the first period. The fuel assembly operated for the time length of the first period refers to the fuel assembly actually used for the operation of the nuclear reactor during the first period. That is, the measurement value acquisition unit 20 acquires the actual measurement value of the amount of bending of the fuel assembly after the first period has elapsed since the start of operation. For example, for the fuel assembly operated during the first period in an arbitrary nuclear reactor, the amount of bending is measured, and the measurement value acquisition unit 20 acquires the measured value of the amount of bending as the measurement value of the amount of bending. The amount of bending here may refer to, for example, as shown in FIG. 3, the distance E between the straight line AX connecting the center points of the cross sections at both ends in the Z direction of the fuel assembly and the center point of the cross section at a predetermined position in the Z direction of the fuel assembly. In the example of the present embodiment, the measurement value acquisition unit 20 acquires the measurement values of the amount of bending at the central position P1 in the Z direction of the fuel assembly and the upper position P2 located above the central position P1 in the vertical direction. As shown in FIG. 3, for example, the amount of bending at the central position P1 is the distance E1 between the straight line AX and the center point of the cross section of the fuel assembly at the central position P1, and the amount of bending at the upper position P2 is the distance E2 between the straight line AX and the center point of the cross section of the fuel assembly at the upper position P2. However, the amount of bending is not limited to being measured as described above and may be any index indicating the degree of bending of the fuel assembly. Also, the positions for measuring the amount of bending are not limited to the central position P1 and the upper position P2, and the measurement value acquisition unit 20 may acquire the amount of bending at an arbitrary position.

[0022] The measurement value acquisition unit 20 may acquire the measurement value of the amount of bending of the fuel assembly operated for the time length of the first period by any method. For example, the measurement value acquisition unit 20 may acquire the measurement of the amount of bending input to the input unit 12, or may acquire the measurement of the amount of bending from an external server or the like via a communication unit (not shown). The first period may be of any length, but is preferably the operation time of a general one cycle, and is 13 months in the example of the present embodiment.

[0023] Hereinafter, the measured value of the bending amount of the fuel assembly operated for the time length of the first period will be described as the "measured value of the bending amount" as appropriate.

[0024] (Predicted value calculation unit) Based on the measured value of the bending amount acquired by the measured value acquisition unit 20, the predicted value calculation unit 22 calculates the bending coefficient F QB of the fuel assembly to be operated for the time length of the second period after the second period has elapsed. The fuel assembly to be operated for the time length of the second period refers to the fuel assembly assumed to be used for the operation in a predetermined nuclear reactor during the second period. That is, the measured value acquisition unit 20 calculates the predicted value of the bending coefficient F QB of the fuel assembly assuming that the second period has elapsed since the start of operation. The second period may be an arbitrary length longer than the first period, but in the example of this embodiment, it is 18 months. The bending coefficient F QB is a coefficient indicating the degree of influence of the bending amount on the output of the fuel assembly, and can be said to be a coefficient indicating the degree of influence on the coefficient F Q due to the bending amount. Note that the fuel assembly for which the measured value of the bending amount is acquired (the fuel assembly whose bending amount after the first period is measured) and the fuel assembly for which the predicted value of the bending coefficient F QB is calculated after the second period has elapsed are not limited to those with the same design, nor are they limited to those used in the same nuclear reactor.

[0025] FIG. 5 is a graph for explaining the calculation of the bending coefficient. In the present embodiment, the predicted value calculation unit 22 calculates a predicted value of the amount of bending of the fuel assembly operated for the time length of the second period based on the measured value of the amount of bending. In the present embodiment, the predicted value calculation unit 22 calculates a predicted value of the amount of bending at each time (each timing until the second period elapses) based on the measured value of the amount of bending. Note that each timing until the second period elapses in the present embodiment may be any timing until the second period elapses, and the number of timings and the period for each timing (the time from one timing to the next timing) may be arbitrary. However, it is preferable that each timing until the second period elapses includes at least the timing when the second period has elapsed.

[0026] The predicted value calculation unit 22 may calculate the predicted value of the amount of bending by any method based on the measured value of the amount of bending. However, in the present embodiment, assuming that the fuel assembly operated for the time length of the first period bends at the same progress speed as the progress speed of bending in the first period until the second period, the predicted value of the amount of bending is calculated. More specifically, in the present embodiment, the predicted value calculation unit 22 calculates the change amount per unit time of the amount of bending based on the measured value of the amount of bending after the first period has elapsed, assuming that the amount of bending changes linearly until the first period has elapsed. Then, the predicted value calculation unit 22 calculates the predicted value of the amount of bending after the second period has elapsed based on the change amount per unit time of the amount of bending, assuming that the amount of bending changes linearly until the second period has elapsed. Taking FIG. 5 as an example, the predicted value calculation unit 22 calculates the slope of the straight line L1 connecting the amount of bending at time t0 (operation start timing) and the amount of bending at time t1 (the timing when the first period has elapsed) when the horizontal axis is the operation period and the vertical axis is the amount of bending at the central position P1. Then, the predicted value calculation unit 22 calculates the value of the vertical axis at each time on the straight line LA1 obtained by extending the straight line L1 until the second time t2 (the timing when the second period has elapsed) as the predicted value of the amount of bending at the central position P1 at each time until time t2. Note that the straight lines L2 and LA2 show examples of the measured value and the predicted value of the amount of bending at the upper position P2.

[0027] As described above, in this embodiment, assuming that the amount of bending increases linearly, the predicted value of the amount of bending after the lapse of the second period is calculated, but it is not limited thereto. For example, the amount of bending until the lapse of the first period may be sequentially measured, and based on this, the change amount of the amount of bending per unit time may be calculated for each time zone, and based on the change amount of the amount of bending per unit time for each time zone, the predicted value of the amount of bending after the lapse of the second period may be calculated.

[0028] Based on the predicted value of the amount of bending after the lapse of the second period, the prediction value calculation unit 22 calculates the predicted value of the gap G (gap amount) with the adjacent fuel assembly after the lapse of the second period. In the present embodiment, the prediction value calculation unit 22 calculates the predicted value of the gap G at each time until the lapse of the second period based on the predicted value of the amount of bending at each time until the lapse of the second period. Note that the prediction value calculation unit 22 calculates the predicted value of the gap G based on the predicted value of the amount of bending using a known calculation code indicating the correspondence relationship between the amount of bending and the gap G.

[0029] FIG. 6 is a graph for explaining the calculation of the predicted value of the bending coefficient. Based on the predicted value of the gap G after the lapse of the second period, the prediction value calculation unit 22 calculates the predicted value of the bending coefficient F QB after the lapse of the second period. In the present embodiment, the prediction value calculation unit 22 calculates the predicted value of the bending coefficient F QB at each time until the lapse of the second period based on the predicted value of the gap G at each time until the lapse of the second period. The line LB1 in FIG. 6 shows an example of the predicted value of the bending coefficient F QB at the central position P1, and the line LB2 in FIG. 6 shows an example of the predicted value of the bending coefficient F QB at the upper position P2. Note that the prediction value calculation unit 22 calculates the predicted value of the bending coefficient F QB based on the predicted value of the gap G using a known calculation code indicating the correspondence relationship between the gap G and the bending coefficient F QB after the lapse of the second period.

[0030] In this embodiment, the predicted value calculation unit 22 calculates the predicted value of the bending coefficient F on the assumption that the bending of the fuel assembly is in the primary mode. However, the predicted value calculation unit 22 may set the bending mode of the fuel assembly and calculate the predicted value of the bending coefficient F in the set bending mode. The method for setting the bending mode by the predicted value calculation unit 22 may be arbitrary. For example, the bending mode may be set based on the design data of the fuel assembly to be analyzed. In this case, the predicted value calculation unit 22 may set the actual bending mode of the fuel assembly whose similarity to the design data of the fuel assembly to be analyzed is equal to or greater than the threshold value among the fuel assemblies actually operated for a predetermined period or more as the bending mode of the fuel assembly to be analyzed. The design data here refers to the design values of the characteristics of the fuel assembly, and examples include at least one of the fuel enrichment of the fuel assembly, the length of the fuel assembly, and the installation position of the fuel assembly in the reactor core. Also, the threshold value for the similarity of the design data may be set as appropriate. QB QB

[0031] (Reference coefficient calculation unit) FIG. 7 is a graph for explaining the calculation of the predicted value of the reference coefficient. The reference coefficient calculation unit 24 calculates the predicted value of the reference coefficient F indicating the output of the fuel assembly after the elapse of the second period when the amount of bending is not considered. The reference coefficient F can also be said to refer to the coefficient F when the amount of bending is zero. In this embodiment, the reference coefficient calculation unit 24 calculates the predicted value of the reference coefficient F at each time until the elapse of the second period. The line LC1 in FIG. 7 shows an example of the predicted value of the reference coefficient F at the central position P1, and the line LC2 in FIG. 7 shows an example of the predicted value of the reference coefficient F at the upper position P2. Note that the reference coefficient calculation unit 24 calculates the predicted value of the reference coefficient F based on the operation period using a known calculation code showing the correspondence between the operation period and the reference coefficient F. QZ QZ Q QZ QZ QZ QZ QZ

[0032] (Evaluation unit) ​​​​​​​​​​FIG. 8 is a graph for explaining the evaluation of the fuel assembly. The evaluation unit 26 evaluates the fuel assembly scheduled to be operated for the time length of the second period based on the predicted value of the bending coefficient F QB after the elapse of the second period. In the present embodiment, the evaluation unit 26 evaluates the fuel assembly scheduled to be operated for the time length of the second period based on the predicted value of the bending coefficient F QB at each time until the elapse of the second period.

[0033] Specifically, the evaluation unit 26 calculates the predicted value of the coefficient F QZ based on the predicted value of the reference coefficient F QB and the predicted value of the bending coefficient F Q , and evaluates the fuel assembly based on the predicted value of the coefficient F Q . In the present embodiment, the evaluation unit 26 calculates, as the predicted value of the coefficient F QZ at that time, the value obtained by multiplying the predicted value of the reference coefficient F QB by the predicted value of the bending coefficient F Q at the same time. The evaluation unit 26 calculates the predicted value of the coefficient F Q at each time until the elapse of the second period. Then, the evaluation unit 26 determines whether the predicted value of the coefficient F Q at each time until the elapse of the second period is less than or equal to the threshold value TH. When all of the predicted values of the coefficient F Q at each time until the elapse of the second period are less than or equal to the threshold value TH, the evaluation unit 26 determines that the design (design data) of the fuel assembly is appropriate. On the other hand, when at least one of the predicted values of the coefficient F Q at each time until the elapse of the second period is higher than the threshold value TH, the evaluation unit 26 determines that the design (design data) of the fuel assembly is inappropriate. Note that the line LD1 in FIG. 8 shows an example of the predicted value of the coefficient F Q at the central position P1, and the line LD2 in FIG. 8 shows an example of the predicted value of the coefficient F Q at the upper position P2. When calculating the predicted values of the coefficient F Q at different positions in the Z direction in this way, the evaluation unit 26 determines whether the predicted value of the coefficient F Q at each position is less than or equal to the threshold value TH. Then, for each position, it is determined whether the coefficient F QIf there is a predicted value higher than the threshold TH among the predicted values, the evaluation unit 26 determines that the design (design data) of the fuel assembly is inappropriate. Note that the threshold TH may be set arbitrarily.

[0034] The evaluation unit 26 may display the evaluation result of the fuel assembly on the display unit 14. For example, when the evaluation unit 26 determines that the design of the fuel assembly is inappropriate, it may cause the display unit 14 to display information indicating that the design is inappropriate, and when it determines that the design of the fuel assembly is appropriate, it may cause the display unit 14 to display information indicating that the design is appropriate.

[0035] When it is determined that the design of the fuel assembly is inappropriate, the user may update the design data of the fuel assembly. Then, for the fuel assembly with the updated design data, the analysis device 10 may perform an evaluation in the same manner as described above. Also, when it is determined that the design of the fuel assembly is inappropriate, the analysis device 10 may automatically update the design data of the fuel assembly. In this case, for example, the analysis device 10 is based on the predicted value of the coefficient F Q for the fuel assembly determined to have an inappropriate design, for example, the coefficient F Q and may update the design data of the fuel assembly so that the predicted value becomes lower.

[0036] As described above, the analysis device 10 according to the present embodiment calculates the predicted value of the bending coefficient F QB of the fuel assembly after the elapse of the second period, which is longer than the first period, from the measured value of the amount of bending of the fuel assembly after the elapse of the first period, and evaluates the fuel assembly scheduled to be operated for the time length of the second period based on this. According to the present embodiment, from the actually measured value of the amount of bending after the elapse of the first period, the degree of influence (bending coefficient F QB ) of the amount of bending after the elapse of the second period on the output is predicted, and based on this, the fuel assembly scheduled to be operated in the second period is evaluated. Therefore, it is possible to appropriately evaluate the fuel assembly scheduled to extend the operation time before operation.

[0037] (Processing flow) Next, the processing flow by the analysis device 10 will be described. FIG. 9 is a flowchart for explaining the processing flow of the analysis device according to the present embodiment. As shown in FIG. 9, the analysis device 10 acquires a measurement value of the amount of bending of the fuel assembly after the first period has elapsed since the start of operation by the measurement value acquisition unit 20 (step S10), and based on the acquired measurement value of the amount of bending, the prediction value calculation unit 22 calculates a predicted value of the amount of bending of the fuel assembly at each timing from the start of operation until the second period has elapsed (step S12). Based on the predicted value of the amount of bending, the prediction value calculation unit 22 calculates a predicted value of the gap of the fuel assembly at each timing until the second period has elapsed (step S14), and based on the predicted value of the gap, calculates a predicted value of the bending coefficient F QB of the fuel assembly at each timing until the second period has elapsed (step S16). Further, the analysis device 10 calculates a predicted value of the reference coefficient F QZ of the fuel assembly at each timing from the start of operation until the second period has elapsed when not considering the amount of bending, by the reference coefficient calculation unit 24 (step S18). Note that the execution order of step S18 and steps S10 to S16 may be arbitrary.

[0038] The prediction value calculation unit 22 calculates a predicted value of the coefficient F QB of the fuel assembly at each timing until the second period has elapsed, based on the predicted value of the bending coefficient F QZ and the predicted value of the reference coefficient F Q (step S20), and the evaluation unit 26 evaluates the fuel assembly based on the predicted value of the coefficient F Q (step S22).

[0039] (Effect) The analysis method according to the first aspect of the present disclosure includes a step of acquiring a measurement value of the amount of bending of a fuel assembly operated for a time length of a first period, and based on the measurement value of the amount of bending, a bending coefficient F indicating the degree of influence on the output by the amount of bending at each timing until the second period, which is longer than the first period, elapses, for the fuel assembly operated for the time length of the second period. QB A step of calculating a predicted value of QBevaluating a fuel assembly to be operated for a length of time in a second period based on the predicted value; and the like. According to the present disclosure, from the measured value of the amount of bending after the first period, the degree of influence (bending coefficient F QB ) exerted on the output by the amount of bending until the second period is predicted, and based on this, the fuel assembly scheduled to be operated in the second period is evaluated. Therefore, it is possible to appropriately evaluate a fuel assembly scheduled to extend the operation time before operation.

[0040] The analysis method according to the second aspect of the present disclosure is the analysis method according to the first aspect, wherein in the step of calculating the predicted value of the bending coefficient F QB , based on the measured value of the amount of bending, the predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses is calculated, and based on the predicted value of the amount of bending, the predicted value of the gap amount with the adjacent fuel assembly at each timing until the second period elapses is calculated, and based on the predicted value of the gap amount, the predicted value of the bending coefficient F QB is calculated. According to the present disclosure, in order to predict the amount of bending from the measured value of the amount of bending after the first period until the second period elapses and based on this, predict the bending coefficient F QB , the bending coefficient F Q until the second period elapses can be predicted with high accuracy, and a fuel assembly scheduled to extend the operation time can be appropriately evaluated.

[0041] The analysis method according to the third aspect of the present disclosure is the analysis method according to the second aspect, wherein in the step of calculating the predicted value of the bending coefficient F QB , based on the measured value of the amount of bending, the amount of change per unit time of the amount of bending is calculated assuming that the amount of bending changes linearly until the first period elapses, and assuming that the amount of bending changes linearly until the second period elapses, based on the amount of change per unit time, the predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses is calculated. According to the present disclosure, when predicting the amount of bending from the measured value of the amount of bending after the first period until the second period elapses, assuming that the amount of bending changes linearly, the amount of bending is evaluated on the safe side, and a fuel assembly scheduled to extend the operation time can be appropriately evaluated.

[0042] The analysis method according to the fourth aspect of the present disclosure is the analysis method according to any one of the first to third aspects, and is a reference coefficient F indicating the output at each timing until the second period elapses when the amount of bending is not considered QZ and further includes a step of calculating, and in the step of evaluating the fuel assembly, the reference coefficient F QZ and the bending coefficient F QB Based on the heat flux heat channel coefficient F calculated based on Q evaluate the fuel assembly operated for the time length of the second period. According to the present disclosure, since the fuel assembly is evaluated based on the heat flux heat channel coefficient F Q it is possible to appropriately evaluate a fuel assembly whose operation time is planned to be extended.

[0043] The analysis method according to the fifth aspect of the present disclosure is the analysis method according to the fourth aspect, and in the step of evaluating the fuel assembly, at each timing until the second period elapses, the heat flux heat channel coefficient F Q If each of them is less than or equal to the threshold value TH, it is evaluated that the design of the fuel assembly is appropriate, and at each timing until the second period elapses, the heat flux heat channel coefficient F Q If at least one of them is higher than the threshold value TH, it is evaluated that the design of the fuel assembly is inappropriate. According to the present disclosure, since the fuel assembly is evaluated based on the heat flux heat channel coefficient F Q at each timing, it is possible to appropriately evaluate a fuel assembly whose operation time is planned to be extended.

[0044] The analysis method according to the sixth aspect of the present disclosure is the analysis method according to the fifth aspect, and in the step of evaluating the fuel assembly, when it is evaluated that the design of the fuel assembly is inappropriate, it further includes a step of redesigning the fuel assembly. According to the present disclosure, it is possible to design a fuel assembly whose operation time is planned to be extended so that the output does not become excessive.

[0045] The program according to the seventh aspect of the present disclosure includes steps of: obtaining a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; based on the measured value of the amount of bending, determining a bending coefficient F indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for a fuel assembly operated for a time length longer than the first period. QB calculating a predicted value of; QB evaluating a fuel assembly operated for a time length of the second period based on the predicted value of the bending coefficient F. According to the present disclosure, a fuel assembly whose operation time is planned to be extended can be appropriately evaluated before operation.

[0046] The analysis device 10 according to the eighth aspect of the present disclosure includes: a measurement value acquisition unit 20 that obtains a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; based on the measured value of the amount of bending, a bending coefficient F indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for a fuel assembly operated for a time length longer than the first period. QB a predicted value calculation unit 22 that calculates a predicted value of; QB an evaluation unit 26 that evaluates a fuel assembly operated for a time length of the second period based on the predicted value of the bending coefficient F. According to the present disclosure, a fuel assembly whose operation time is planned to be extended can be appropriately evaluated before operation.

[0047] As described above, the embodiments of the present disclosure have been described, but the embodiments are not limited by the contents of these embodiments. Further, the components described above include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or changes of the components can be made without departing from the gist of the above-described embodiments.

Description of Reference Numerals

[0048] 10 Analysis device 20 Measurement value acquisition unit 22 Predicted value calculation unit 24 Reference coefficient calculation unit 26 Evaluation Unit F Q Coefficient (Heat Flux Heat Waterway Coefficient) F QB Bending Coefficient F QZ Reference Coefficient

Claims

1. Obtaining a measurement value of the amount of bending of a fuel assembly operated for a time length of a first period; Based on the measurement value of the amount of bending, calculating a predicted value of a bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for a fuel assembly operated for a time length longer than the first period; Evaluating the fuel assembly operated for the time length of the second period based on the predicted value of the bending coefficient; Including; In the step of calculating the predicted value of the bending coefficient, Based on the measurement value of the amount of bending, calculating a predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses; Based on the predicted value of the amount of bending, calculating a predicted value of the gap amount with an adjacent fuel assembly at each timing until the second period elapses; Based on the predicted value of the gap amount, calculating a predicted value of the bending coefficient at each timing until the second period elapses; Based on the measurement value of the amount of bending, calculating a change amount per unit time of the amount of bending when it is assumed that the amount of bending changes linearly until the first period elapses; Assuming that the amount of bending changes linearly until the second period elapses, and calculating a predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses based on the change amount per unit time. Analysis method.

2. Obtaining a measurement value of the amount of bending of a fuel assembly operated for a time length of a first period; Based on the measurement value of the amount of bending, calculating a predicted value of a bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for a fuel assembly operated for a time length longer than the first period; Evaluating the fuel assembly operated for the time length of the second period based on the predicted value of the bending coefficient; Calculating a reference coefficient indicating the output at each timing until the second period elapses when not considering the amount of bending, including; In the step of evaluating the fuel assembly, evaluating the fuel assembly operated for the time length of the second period based on a heat flux heat channel coefficient calculated based on the reference coefficient and the bending coefficient. Analysis method.

3. In the step of calculating the predicted value of the bending coefficient, Based on the measured value of the amount of bending, calculate the predicted value of the amount of bending of the fuel assembly at each timing until the end of the second period. Based on the predicted value of the amount of bending, calculate the predicted value of the gap amount with the adjacent fuel assemblies at each timing until the end of the second period. The analysis method according to claim 2, wherein based on the predicted value of the gap amount, calculate the predicted value of the bending coefficient at each timing until the end of the second period.

4. In the step of calculating the predicted value of the bending coefficient, Based on the measured value of the amount of bending, calculate the change amount per unit time of the amount of bending when it is assumed that the amount of bending changes linearly until the end of the first period. Assuming that the amount of bending changes linearly until the end of the second period, calculate the predicted value of the amount of bending of the fuel assembly at each timing until the end of the second period based on the change amount per unit time. The analysis method according to claim 3.

5. Further include the step of calculating a reference coefficient indicating the output at each timing until the end of the second period when not considering the amount of bending. In the step of evaluating the fuel assembly, evaluate the fuel assembly operated for the time length of the second period based on the heat flux heat channel coefficient calculated based on the reference coefficient and the bending coefficient. The analysis method according to claim 1.

6. In the step of evaluating the fuel assembly, If each of the heat flux heat channel coefficients at each timing until the end of the second period is below the threshold value, evaluate that the design of the fuel assembly is appropriate. The analysis method according to claim 5, wherein if at least one of the heat flux heat channel coefficients at each timing until the end of the second period is higher than the threshold value, evaluate that the design of the fuel assembly is inappropriate.

7. The analysis method according to claim 6, further including the step of redesigning the fuel assembly when it is evaluated that the design of the fuel assembly is inappropriate.

8. Obtain the measured value of the amount of bending of the fuel assembly operated for the time length of the first period. Based on the measured value of the amount of bending, calculate the predicted value of the bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the end of the second period of the fuel assembly operated for the time length of the second period longer than the first period. Based on the predicted value of the bending coefficient, evaluating the fuel assembly operated for the time length of the second period; causing a computer to execute; In the step of calculating the predicted value of the bending coefficient, Based on the measured value of the amount of bending, calculating a predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses; Based on the predicted value of the amount of bending, calculating a predicted value of the gap amount with an adjacent fuel assembly at each timing until the second period elapses; Based on the predicted value of the gap amount, calculating a predicted value of the bending coefficient at each timing until the second period elapses; Based on the measured value of the amount of bending, calculating the change amount per unit time of the amount of bending when it is assumed that the amount of bending changes linearly until the first period elapses; Assuming that the amount of bending changes linearly until the second period elapses, and calculating a predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses based on the change amount per unit time; Program.

9. A step of obtaining a measured value of the amount of bending of a fuel assembly operated for the time length of the first period; Based on the measured value of the amount of bending, calculating a predicted value of the bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for the fuel assembly operated for the time length of the second period longer than the first period; Based on the predicted value of the bending coefficient, evaluating the fuel assembly operated for the time length of the second period; Calculating a reference coefficient indicating the output at each timing until the second period elapses when not considering the amount of bending; causing a computer to execute; In the step of evaluating the fuel assembly, evaluating the fuel assembly operated for the time length of the second period based on the heat flux heat waterway coefficient calculated based on the reference coefficient and the bending coefficient; Program.

10. A measured value acquisition unit that acquires a measured value of the amount of bending of a fuel assembly operated for the time length of the first period; A predicted value calculation unit that calculates a predicted value of the bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period elapses for the fuel assembly operated for the time length of the second period longer than the first period based on the measured value of the amount of bending; An evaluation unit that evaluates the fuel assembly operated for the time length of the second period based on the predicted value of the bending coefficient; comprising; The predicted value calculation unit: Based on the measured value of the amount of bending, calculates the predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses; Based on the predicted value of the amount of bending, calculates the predicted value of the gap amount with the adjacent fuel assemblies at each timing until the second period elapses; Based on the predicted value of the gap amount, calculates the predicted value of the bending coefficient at each timing until the second period elapses; Based on the measured value of the amount of bending, calculates the change amount per unit time of the amount of bending when it is assumed that the amount of bending changes linearly until the first period elapses; Assuming that the amount of bending changes linearly until the second period elapses, based on the change amount per unit time, calculates the predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses; Analysis device.

11. A measured value acquisition unit that acquires a measured value of the amount of bending of a fuel assembly operated for the time length of the first period; Based on the measured value of the amount of bending, calculates a predicted value of a bending coefficient indicating the degree of influence on the output by the amount of bending at each timing until the second period, which is longer than the first period, elapses, for the fuel assembly operated for the time length of the second period; A reference coefficient calculation unit that calculates a reference coefficient indicating the output at each timing until the second period elapses when the amount of bending is not considered; An evaluation unit that evaluates the fuel assembly operated for the time length of the second period based on the predicted value of the bending coefficient; comprising; The evaluation unit evaluates the fuel assembly operated for the time length of the second period based on the heat flux heat water channel coefficient calculated based on the reference coefficient and the bending coefficient; Analysis device.

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