JP2023175447A - Analysis method, program and analysis device - Google Patents

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

The present disclosure relates to an analysis method, a program, and an analysis device.

Techniques for evaluating the characteristics of nuclear reactors are known. For example, Patent Document 1 describes that a heat flux hydrothermal coefficient including uncertainty due to the amount of bending is calculated for a plurality of bending patterns that are perturbed based on a probability distribution of the amount of bending of a fuel assembly. .

JP2022-19280A

In recent years, efforts have been made to extend the operating time per cycle of fuel assemblies, and there is a need to appropriately evaluate fuel assemblies whose operating time is scheduled to be extended before operation.

The present disclosure solves the above-mentioned problems, and aims to provide an analysis method, program, and analysis device that can appropriately evaluate a fuel assembly whose operation time is scheduled to be extended before operation.

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

The program according to the present disclosure includes the steps of: acquiring a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; calculating a predicted value of a bending coefficient indicating the degree of influence on the output due to the amount of bending at each timing until the second period elapses of a fuel assembly operated for a time length of two periods; A computer is caused to perform a step of evaluating the fuel assembly operated for the time length of the second period based on the predicted value of the coefficient.

The analysis device according to the present disclosure includes a measurement value acquisition unit that acquires a measurement value of the amount of bending of a fuel assembly operated for a time length of a first period; A prediction that calculates a predicted value of a curvature coefficient indicating the degree of influence on the output due to the amount of curvature at each timing until the second period elapses, of a fuel assembly operated for a second period that is longer than the second period. The fuel assembly includes a value calculation section, and an evaluation section that evaluates the fuel assembly operated during the second period based on the predicted value of the bending coefficient.

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

FIG. 1 is an explanatory diagram schematically showing a reactor core to be analyzed. FIG. 2 is a cross-sectional view of the fuel assembly to be analyzed, taken along a plane perpendicular to the axial direction. FIG. 3 is an explanatory diagram schematically showing a portion of a plurality of fuel assemblies. FIG. 4 is a schematic block diagram of the analysis device according to this embodiment. FIG. 5 is a graph for explaining calculation of the bending coefficient. FIG. 6 is a graph for explaining calculation of the predicted value of the bending coefficient. FIG. 7 is a graph for explaining calculation of the predicted value of the reference coefficient. FIG. 8 is a graph for explaining the evaluation of fuel assemblies. FIG. 9 is a flowchart illustrating the processing flow of the analysis device according to this embodiment.

Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the present disclosure is not limited to this embodiment, and if there are multiple embodiments, the present disclosure also includes a configuration in which each embodiment is combined.

(core)
FIG. 1 is an explanatory diagram schematically showing a core to be analyzed, and FIG. 2 is a cross-sectional view of a fuel assembly to be analyzed, taken along a plane perpendicular to the axial direction. The analysis device 10 according to this embodiment is a device for analyzing core characteristics of a nuclear reactor, and more specifically, a device for evaluating fuel assemblies 6 in the reactor core. As shown in FIG. 1, a nuclear reactor houses a reactor core 5 that is the object of core design. This core 5 includes a plurality of fuel assemblies 6. Note that the fuel exchange is performed in units of six fuel assemblies.

(Fuel assembly and fuel rod)
Each fuel assembly 6 includes a plurality of fuel rods 29 having fuel pellets 30 and cladding tubes 31 that cover 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 an in-core nuclear instrumentation 35 can be inserted therein. The fuel rod 29 has a plurality of cylindrical fuel pellets 30 arranged side by side in the axial direction, and the outside thereof is covered with a cladding tube 31.

The fuel assembly 6 is formed to have a rectangular cross section and is composed of, for example, 17×17 cells 40. Of the 17×17 cells 40, a control rod 34 is inserted into each of the 24 cells 40, and an in-core nuclear 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 nuclear instrumentation 35 is inserted is called an instrumentation guide tube. Furthermore, fuel rods 29 are inserted into the other cells 40, respectively. Note that when the fuel assembly 6 is used in a boiling water reactor (BWR), the outside of the fuel assembly 6 is covered with 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. An inter-assembly gap 32 exists outside the channel box in the case of BWR, and outside the fuel assembly 6 in the case of PWR.

(About bending that occurs in the fuel assembly)
FIG. 3 is an explanatory diagram schematically showing a portion of a plurality of fuel assemblies. In the following description, the axial direction of the fuel assembly 6 will be referred to as the "Z direction," one direction perpendicular to the axial direction will be referred to as the "X direction," and the direction perpendicular to the X and Z directions will be referred to as the "Y direction." As shown in FIG. 3, the plurality of fuel assemblies 6 are arranged side by side along the X direction and the Y direction.

The fuel assembly 6 may be bent. At this time, the fuel assembly 6 curves in an uneven manner in the X direction or the Y direction, as illustrated in FIG. 3 . 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 is locally promoted, and the local output may increase. Therefore, the output of the fuel assembly 6 may be affected by bending (change in 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 for the output of the fuel assembly 6 while taking into account the influence of bending. Note that, as shown in FIG. 3, in this embodiment, the analysis device 10 performs the evaluation assuming that the bending of the fuel assembly 6 is in the first mode. However, the present invention is not limited thereto, and the analysis device 10 may perform the analysis assuming that the bending of the fuel assembly 6 is in a mode other than the primary mode (for example, the secondary mode or the tertiary mode).

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

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

The input unit 12 is, for example, an input device such as a keyboard, and receives information input by a user of the analysis device 10. The display unit 14 is, for example, a display device such as a monitor, and displays the analysis results by the analysis device 10. The storage unit 16 is a memory that stores various information such as calculation contents and programs of the control unit 18, and includes, for example, a main storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and an HDD ( At least one external storage device such as a hard disk drive.

The control unit 18 is an arithmetic device, and includes, for example, an arithmetic circuit such as a CPU (Central Processing Unit). The control unit 18 includes a measured value acquisition unit 20, a predicted value calculation unit 22, a reference coefficient calculation unit 24, and an evaluation unit 26. The control unit 18 reads a program (software) from the storage unit 16 and executes it to implement the measured value acquisition unit 20, predicted value calculation unit 22, reference coefficient calculation unit 24, and evaluation unit 26, and performs the processing. Execute. Note that the control unit 18 may execute the process using one CPU, or may include a plurality of CPUs and execute the process using the plurality of CPUs. Further, at least a portion of the measured value acquisition section 20, the predicted value calculation section 22, the reference coefficient calculation section 24, and the evaluation section 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 that can be read by the analysis device 10.

(Measurement value acquisition section)
The measured value acquisition unit 20 acquires a measured value of the amount of bending of the fuel assembly operated during the first period. The fuel assemblies operated during the first period refer to the fuel assemblies that were actually used in the operation of the nuclear reactor during the first period. That is, the measured value acquisition unit 20 acquires the actual measured value of the amount of bending of the fuel assembly after the first period has passed since the start of operation. For example, the amount of bending is measured for a fuel assembly operated during the first period in an arbitrary nuclear reactor, and the measurement value acquisition unit 20 uses the measured value of the amount of bending as the measured value of the amount of bending. get. The amount of bending here means, for example, as shown in FIG. It may refer to the distance E from the center point of the cross section. In the example of this embodiment, the measured value acquisition unit 20 obtains the measured value of the bending amount at the center position P1 of the fuel assembly in the Z direction and at the upper position P2 located vertically above the center position P1. get. As shown in FIG. 3, for example, the amount of bending at the center 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 center position P1, and the amount of bending at the upper position P2 is: This 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 what is measured as described above, and may be any index indicating the degree of bending of the fuel assembly. Further, the positions at which the amount of bending is measured are not limited to the center position P1 and the upper position P2, and the measurement value acquisition unit 20 may obtain the amount of bending at any position.

The measured value acquisition unit 20 may acquire the measured value of the bending amount of the fuel assembly operated during the first period using any method. For example, the measurement value acquisition unit 20 may acquire the measurement of the amount of bend inputted into the input unit 12, or may acquire the measurement of the amount of bend from an external server or the like via a communication unit (not shown). good. Note that the first period may have any length, but is preferably the operating time of one general cycle, and is 13 months in the example of this embodiment.

Hereinafter, the measured value of the amount of bending of the fuel assembly operated during the time length of the first period will be appropriately referred to as "measured value of the amount of bending."

(Predicted value calculation unit)
The predicted value calculation unit 22 calculates the bending coefficient F QB after the second period has elapsed for the fuel assembly operated during the second period based on the measured value of the bending amount acquired by the measured value acquisition unit _20. Calculate the predicted value of The fuel assembly operated during the second period refers to a fuel assembly assumed to be used for operation in a predetermined nuclear reactor during the second period. That is, the measured value acquisition unit 20 calculates a predicted value of the bending coefficient _FQB of the fuel assembly assuming that the second period has passed since the start of operation. The second period may be any length period longer than the first period, but in the example of this embodiment, it is 18 months. The curvature coefficient _FQB is a coefficient indicating the degree of influence of the amount of curvature on the output of the fuel assembly, and can be said to be a coefficient indicating the degree of influence of the amount of curvature on the _{coefficient FQ} . In addition, the fuel assembly for which the measured value of the bending amount was obtained (the fuel assembly for which the bending amount after the first period was measured) and the target for calculating the predicted value of the bending coefficient F _QB after the second period has elapsed. The fuel assemblies to be used are not limited to those having the same design, and are not limited to those used in the same nuclear reactor.

FIG. 5 is a graph for explaining calculation of the bending coefficient. In the present embodiment, the predicted value calculating unit 22 calculates a predicted value of the amount of bending of the fuel assembly operated during the second period based on the measured value of the amount of bending. In the present embodiment, the predicted value calculation unit 22 calculates the predicted value of the amount of curvature at each time until the second period elapses (each timing until the second period elapses) based on the measured value of the amount of curvature. . In addition, in this embodiment, each timing until the second period passes (each time until the second period passes) may be any timing until the second period passes, and the number of timings, The period for each timing (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 at which the second period has elapsed.

The predicted value calculation unit 22 may calculate the predicted value of the amount of bending using any method based on the measured value of the amount of bending, but in this embodiment, the predicted value of the amount of bending is A predicted value of the amount of bending is calculated by assuming that the aggregate progresses at the same speed as the bending speed in the first period until the second period. More specifically, in the present embodiment, the predicted value calculation unit 22 assumes that the amount of bending changes linearly until the first period elapses, and based on the measured value of the amount of bending after the first period, Calculate the amount of change in the amount of bending per unit time. Then, the predicted value calculation unit 22 predicts the amount of bending after the second period has elapsed based on the amount of change in the amount of bending per unit time, assuming that the amount of bending has changed linearly until the second period has elapsed. Calculate the value. Using FIG. 5 as an example, the predicted value calculation unit 22 calculates the amount of bending at time t0 (operation start timing) and the amount of bending at time t1( The slope of the straight line L1 connecting the amount of bending at the timing when the first period has elapsed is calculated. Then, the predicted value calculation unit 22 calculates the values on the vertical axis at each time in the straight line LA1, which is obtained by extending the straight line L1 to the second time t2 (the timing at which the second period has elapsed), to the center position P1 at each time up to the time t2. Calculated as the predicted value of the amount of bending at . Note that the straight lines L2 and LA2 show examples of measured values and predicted values of the amount of bending at the upper position P2.

In this manner, in the present embodiment, the predicted value of the amount of bending after the second period has elapsed is calculated on the assumption that the amount of bending increases linearly, but the present invention is not limited thereto. For example, the amount of bending is measured sequentially until the first period elapses, and based on that, the amount of change in the amount of bending per unit time is calculated for each time period, and the amount of bending per unit time for each time period is calculated. A predicted value of the amount of bending after the second period has elapsed may be calculated based on the amount of change in the hit.

The predicted value calculation unit 22 calculates a predicted value of the gap G (gap amount) between adjacent fuel assemblies after the second period has elapsed, based on the predicted value of the bending amount after the second period has elapsed. In this embodiment, the predicted value calculation unit 22 calculates the predicted value of the gap G at each time until the second period elapses, based on the predicted value of the bend amount at each time until the second period elapses. Note that the predicted value calculation unit 22 calculates the predicted value of the gap G based on the predicted value of the curved amount using a known calculation code that indicates the correspondence between the curved amount and the gap G.

FIG. 6 is a graph for explaining calculation of the predicted value of the bending coefficient. The predicted value calculation unit 22 calculates the predicted value of the bending coefficient _FQB after the second period has elapsed, based on the predicted value of the gap G after the second period has elapsed. In the present embodiment, the predicted value calculation unit 22 calculates the predicted value of the curve coefficient _FQB at each time until the second period elapses, based on the predicted value of the gap G at each time until the second period elapses. A line LB1 in FIG. 6 shows an example of a predicted value of the bending coefficient _FQB at the center position P1, and a line LB2 in FIG. 6 shows an example of a predicted value of the bending coefficient _FQB at the upper position P2. Note that the predicted value calculation unit 22 calculates the predicted value of the bending coefficient _FQB based on the predicted value of the gap G using a known calculation code indicating the correspondence between the gap G and the bending coefficient _FQB .

In this embodiment, the predicted value calculation unit 22 calculates the predicted value of the bending coefficient F _QB on the assumption that the bending of the fuel assembly is in the first 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 _QB in the set bending mode. Although the method of setting the bending mode by the predicted value calculation unit 22 may be arbitrary, for example, the bending mode may be set based on design data of the fuel assembly to be analyzed. In this case, the predicted value calculation unit 22 calculates the actual value of the fuel assembly whose similarity with the design data of the fuel assembly to be analyzed is equal to or higher than the threshold value, among the fuel assemblies that have been actually operated for a predetermined period or longer. The bending mode may be set to 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, such as the fuel enrichment of the fuel assembly, the length of the fuel assembly, and the installation position of the fuel assembly in the core. One example is. Further, a threshold value regarding the degree of similarity of design data may be set as appropriate.

(Standard coefficient calculation unit)
FIG. 7 is a graph for explaining calculation of the predicted value of the reference coefficient. The reference coefficient calculation unit 24 calculates a predicted value of a reference coefficient _FQZ indicating the output of the fuel assembly after the second period has elapsed without considering the amount of bending. The reference coefficient _FQZ can also be said to refer to the coefficient _FQ when the amount of bending is set to zero. In this embodiment, the reference coefficient calculation unit 24 calculates the predicted value of the reference coefficient _FQZ at each time until the second period has elapsed. A line LC1 in FIG. 7 shows an example of the predicted value of the reference coefficient F _QZ at the center position P1, and a line LC2 in FIG. 7 shows an example of the predicted value of the reference coefficient F _QZ at the upper position P2. Note that the reference coefficient calculating unit 24 calculates the predicted value of the reference coefficient _FQZ based on the operating period using a known calculation code that indicates the correspondence between the operating period and the reference coefficient _FQZ .

(Evaluation Department)
FIG. 8 is a graph for explaining the evaluation of fuel assemblies. The evaluation unit 26 evaluates the fuel assembly scheduled to be operated during the second period based on the predicted value of the bending coefficient _FQB after the second period has elapsed. In the present embodiment, the evaluation unit 26 evaluates the fuel assembly scheduled to be operated during the second period based on the predicted value of the bending coefficient _FQB at each time until the second period elapses.

Specifically, the evaluation unit 26 calculates the predicted value of the coefficient _FQ based on the predicted value of the reference coefficient FQZ and the predicted value of the bending coefficient _FQB , and calculates the predicted value of the coefficient _FQ based on the predicted value of the coefficient _FQ . , evaluate fuel assemblies. In this embodiment, the evaluation unit 26 calculates a value obtained by multiplying the predicted value of the reference coefficient _FQZ by the predicted value of the bending coefficient _FQB at the same time as the predicted value of the coefficient _FQ at that time. The evaluation unit 26 calculates the predicted value of the coefficient _FQ at each time until the second period elapses. Then, the evaluation unit 26 determines whether the predicted value of the coefficient _FQ at each time until the second period has elapsed is equal to or less than the threshold value TH. If all of the predicted values of the coefficient _FQ at each time until the second period has elapsed are less than or equal to the threshold TH, the evaluation unit 26 determines that the design (design data) of the fuel assembly is appropriate. On the other hand, if at least one of the predicted values of the coefficient _FQ at each time until the second period elapses is higher than the threshold TH, the evaluation unit 26 determines that the design (design data) of the fuel assembly is inappropriate. to decide. Note that the line LD1 in FIG. 8 shows an example of the predicted value of the coefficient _FQ at the center position P1, and the line LD2 in FIG. 8 shows an example of the predicted value of the coefficient _FQ at the upper position P2. When calculating the predicted value of the coefficient _FQ at different positions in the Z direction in this manner, the evaluation unit 26 determines whether the predicted value of the coefficient _FQ is equal to or less than the threshold value TH at each position. If any of the predicted values of the coefficient _FQ for each position is higher than the threshold TH, the evaluation unit 26 determines that the design (design data) of the fuel assembly is inappropriate. Note that the threshold value TH may be set arbitrarily.

The evaluation section 26 may display the evaluation results for the fuel assembly on the display section 14. For example, if the evaluation unit 26 determines that the design of the fuel assembly is inappropriate, it displays information to the effect that the design is inappropriate on the display unit 14, and indicates that the design of the fuel assembly is appropriate. If it is determined that the design is appropriate, information indicating that the design is appropriate may be displayed on the display unit 14.

The user may update the design data of the fuel assembly when it is determined that the design of the fuel assembly is inappropriate. Then, the analysis device 10 may evaluate the fuel assembly whose design data has been updated in the same manner as described above. Further, if 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, based on the predicted value of the coefficient _FQ for the fuel assembly judged to be inappropriately designed, the analysis device 10 may calculate the design data of the fuel assembly so that the predicted value of the coefficient _FQ becomes low. may be updated.

As described above, the analysis device 10 according to the present embodiment calculates the bending coefficient of the fuel assembly after the second period, which is longer than the first period, from the measured value of the bending amount of the fuel assembly after the first period. A predicted value of F _QB is calculated, and based on the predicted value, a fuel assembly scheduled to be operated for the time length of the second period is evaluated. According to this embodiment, the degree of influence of the amount of bending after the second period has elapsed (bending coefficient F _QB ) on the output is predicted from the measured value of the amount of bending after the elapse of the first period, and based on this, the degree of influence of the amount of bending after the elapse of the second period is predicted. Evaluate fuel assemblies scheduled for operation. Therefore, a fuel assembly whose operating time is scheduled to be extended can be appropriately evaluated before operation.

(Processing flow)
Next, a processing flow of processing by the analysis device 10 will be explained. FIG. 9 is a flowchart illustrating the processing flow of the analysis device according to this embodiment. As shown in FIG. 9, the analysis device 10 uses the measured value acquisition unit 20 to acquire the measured value of the bending amount of the fuel assembly after the first period has passed since the start of operation (step S10), and calculates the predicted value. The calculation unit 22 calculates a predicted value of the amount of bending of the fuel assembly at each timing from the start of operation to the passage of the second period based on the obtained measured value of the amount of bending (step S12). The predicted value calculation unit 22 calculates the predicted value of the gap of the fuel assembly at each timing until the elapse of the second period based on the predicted value of the amount of bending (step S14), and calculates the predicted value of the gap of the fuel assembly at each timing until the second period elapses, based on the predicted value of the gap. A predicted value of the bending coefficient _FQB of the fuel assembly at each timing up to the elapse of time is calculated (step S16). In addition, the analysis device 10 uses the reference coefficient calculation unit 24 to calculate the predicted value of the reference coefficient _FQZ of the fuel assembly at each timing from the start of operation to the passage of the second period when the amount of bending is not considered (step S18). Note that step S18 and steps S10 to S16 may be performed in any order.

The predicted value calculation unit 22 calculates the predicted value of the coefficient _FQ of the fuel assembly at each timing until the second period elapses, based on the predicted value of the bending coefficient _FQB and the predicted value of the reference coefficient _FQZ . (Step S20), and the evaluation unit 26 evaluates the fuel assembly based on the predicted value of the coefficient _FQ (Step S22).

(effect)
The analysis method according to the first aspect of the present disclosure includes the steps of: acquiring a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; A step of calculating a predicted value of a bending coefficient F _QB indicating the degree of influence on the output due to the amount of bending at each timing until the second period elapses for a fuel assembly operated for a longer second period. and evaluating a fuel assembly operated during the second time period based on the predicted value of the bending coefficient _FQB . According to the present disclosure, the degree of influence of the amount of bending on the output (bending coefficient F _QB ) until the elapse of the second period is predicted from the actual value of the amount of bending after the first period has elapsed, and the operation is performed in the second period based on the prediction. Evaluate the fuel assembly that will be used. Therefore, a fuel assembly whose operating time is scheduled to be extended can be appropriately evaluated before operation.

The analysis method according to the second aspect of the present disclosure is the analysis method according to the first aspect, in which in the step of calculating the predicted value of the bending coefficient _FQB , the second period is determined based on the measured value of the bending amount. The predicted value of the amount of bending of the fuel assembly at each timing until the elapse of the second period is calculated, and based on the predicted value of the amount of bending, the amount of gap between adjacent fuel assemblies at each timing until the elapse of the second period is calculated. A predicted value is calculated, and based on the predicted value of the gap amount, a predicted value of the bending coefficient _FQB at each timing until the second period elapses is calculated. According to the present disclosure, the amount of bending until the second period has elapsed is predicted from the actual value of the amount of bending after the first period has elapsed, and the bending coefficient F _QB is predicted based on the measured value, so the bending coefficient F _QB until the elapse of the second period is predicted. can be predicted with high accuracy and appropriately evaluate fuel assemblies that are scheduled to extend their operating time.

The analysis method according to the third aspect of the present disclosure is the analysis method according to the second aspect, in which in the step of calculating the predicted value of the bending coefficient _FQB , the bending amount is determined based on the measured value of the bending amount. Calculate the amount of change per unit time in the amount of bending, assuming that it changes linearly until the passage of one period, and calculate the amount of change per unit time, assuming that the amount of bending changes linearly until the passage of the second period. According to the present disclosure, a predicted value of the amount of bending of the fuel assembly at each timing until the second period elapses is calculated based on the amount of change. When predicting the amount of bending over time, it is assumed that the amount of bending changes linearly, so the amount of bending can be evaluated on the safe side, and fuel assemblies whose operation time is to be extended can be appropriately evaluated.

An analysis method according to a fourth aspect of the present disclosure is an analysis method according to any one of the first to third aspects, in which the output at each timing until the second period elapses when the amount of bending is not considered. The step of evaluating the _fuel assembly further includes the step _of calculating a reference coefficient _{FQZ indicating} Then, evaluate the fuel assembly operated during the second period. According to the present disclosure, since the fuel assembly is evaluated based on the heat flux hydrothermal coefficient _FQ , it is possible to appropriately evaluate the fuel assembly whose operation time is scheduled to be extended.

The analysis method according to the fifth aspect of the present disclosure is the analysis method according to the fourth aspect, in which in the step of evaluating the fuel assembly, the heat flux hydrothermal channel coefficient at each timing until the second period elapses. If each of _FQ is less than or equal to the threshold TH, it is evaluated that the design of the fuel assembly is appropriate, and at least the heat flux hydrothermal coefficient _FQ at each timing until the second period elapses. If one is higher than the threshold TH, it is evaluated that the design of the fuel assembly is inappropriate. According to the present disclosure, fuel assemblies are evaluated based on the heat flux hydrodynamic coefficient _FQ for each timing, so it is possible to appropriately evaluate a fuel assembly whose operation time is scheduled to be extended.

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

A program according to a seventh aspect of the present disclosure includes the steps of: acquiring a measured value of the amount of bending of a fuel assembly operated for a time length of a first period; a step of calculating a predicted value of a bending coefficient F _QB indicating the degree of influence on the output due to the amount of bending at each timing until the second period elapses of a fuel assembly operated for a long second period; , and evaluating the fuel assembly operated during the second period based on the predicted value of the bending coefficient _FQB . According to the present disclosure, a fuel assembly whose operation time is scheduled to be extended can be appropriately evaluated before operation.

The analysis device 10 according to the eighth aspect of the present disclosure includes a measured value acquisition unit 20 that acquires a measured value of the amount of bending of a fuel assembly operated during the time length of the first period, and The prediction of the curvature coefficient _FQB , which indicates the degree of influence on the output due to the amount of curvature at each timing until the second period elapses, of a fuel assembly operated during the second period, which is longer than the first period. It includes a predicted value calculation unit 22 that calculates a value, and an evaluation unit 26 that evaluates a fuel assembly operated during the second period based on the predicted value of the bending coefficient _FQB . According to the present disclosure, a fuel assembly whose operation time is scheduled to be extended can be appropriately evaluated before operation.

Although the embodiment of the present disclosure has been described above, the embodiment is not limited by the content of this embodiment. Furthermore, the above-mentioned components include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that are in a so-called equivalent range. Furthermore, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the constituent elements can be made without departing from the gist of the embodiments described above.

10 Analyzer 20 Measured value acquisition section 22 Predicted value calculation section 24 Standard coefficient calculation section 26 Evaluation section _FQ coefficient (heat flux hydrothermal coefficient)
F _QB bending coefficient F _QZ standard coefficient

Claims (8)

obtaining a measurement of the amount of bending of the fuel assembly operated during the first time period;
Based on the measured value of the amount of bending, the output of the fuel assembly operated during the second period, which is longer than the first period, is determined by the amount of bending at each timing until the second period elapses. calculating a predicted value of a bending coefficient indicating the degree of influence;
evaluating the fuel assembly operated during the second time period based on the predicted value of the bending coefficient;
including,
analysis method. In the step of calculating the predicted value of the bending coefficient,
Based on the measured value of the amount of bending, calculate 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 bending amount, calculate a predicted value of the gap amount between adjacent fuel assemblies at each timing until the second period elapses;
The analysis method according to claim 1, wherein the predicted value of the bending coefficient is calculated at each timing until the second period elapses based on the predicted value of the gap amount. In the step of calculating the predicted value of the bending coefficient,
Based on the measured value of the amount of bending, calculate the amount of change in the amount of bending per unit time, assuming 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, the amount of bending of the fuel assembly at each timing until the second period elapses is determined based on the amount of change per unit time. The analysis method according to claim 2, which calculates a predicted value. further comprising the step of calculating a reference coefficient indicating an output at each timing until the second period elapses when the amount of bending is not considered;
In the step of evaluating the fuel assembly, the fuel assembly operated for the time length of the second period is evaluated based on the heat flux hydrothermal coefficient calculated based on the reference coefficient and the bending coefficient. The analysis method according to claim 1 or claim 2, which evaluates a human body. In the step of evaluating the fuel assembly,
If each of the heat flux hydrothermal coefficients at each timing until the second period elapses is equal to or less than a threshold value, evaluate that the design of the fuel assembly is appropriate,
According to claim 4, if at least one of the heat flux hydrothermal coefficients at each timing until the second period elapses is higher than a threshold value, the design of the fuel assembly is evaluated to be inappropriate. Analysis method described. The analysis method according to claim 5, further comprising the step of redesigning the fuel assembly when the design of the fuel assembly is evaluated to be inappropriate. obtaining a measurement of the amount of bending of the fuel assembly operated during the first time period;
Based on the measured value of the amount of bending, the output of the fuel assembly operated during the second period, which is longer than the first period, is determined by the amount of bending at each timing until the second period elapses. calculating a predicted value of a bending coefficient indicating the degree of influence;
evaluating the fuel assembly operated during the second time period based on the predicted value of the bending coefficient;
make the computer execute
program. a measurement value acquisition unit that acquires a measurement value of the bending amount of the fuel assembly operated for the time length of the first period;
Based on the measured value of the amount of bending, the output of the fuel assembly operated during the second period, which is longer than the first period, is determined by the amount of bending at each timing until the second period elapses. a predicted value calculation unit that calculates a predicted value of a bending coefficient indicating the degree of influence;
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;
including,
Analysis device.

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