Measured value reconstruction method, reconstruction device, and program

Abstract

To provide a method for accurately estimating a measured value of a malfunctioned measuring instrument when the measuring instrument installed in a nuclear reactor has malfunctioned.SOLUTION: A reconstruction method is so configured that when a malfunctioned measuring instrument among a plurality of measuring instruments provided in a nuclear reactor is defined as a malfunctioned measuring instrument and a healthy measuring instrument located close to the malfunctioned measuring instrument as a proximal measuring instrument, a value obtained by multiplying a measured value measured by the malfunctioned measuring instrument at a first time point before the malfunction, a change rate of a neutron reaction rate of a prescribed substance at a position of the malfunctioned measuring instrument from the first time point to a second time point after the malfunction of the malfunctioned measuring instrument, and a ratio of a change rate of a measured value of the proximal measuring instrument from the first time point to the second time point to the change rate of the neutron reaction rate at a position of the proximal measuring instrument from the first time point to the second time point, is defined as a measured value by the malfunctioned measuring instrument at a second time point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a measurement value reconstruction method, a reconstruction device, and a program. [Background technology]

[0002] Detectors that measure neutron flux are placed at various locations inside a nuclear reactor. The neutron flux measured by these detectors is used, for example, to measure the power distribution. If a detector fails during operation of a nuclear power plant, the failed detector cannot be used to measure the power distribution until it is replaced or repaired.

[0003] Patent Document 1 discloses a system that predicts the possibility and scale of an abnormal situation occurring in a blast furnace based on measurement data measured by multiple sensors installed in the furnace. Patent Document 1 describes a technology that, when a sensor fails, estimates the measurement value of the failed sensor using, for example, the average value of the measurement values ​​of surrounding sensors. In the case of a nuclear reactor, since the state of fuel differs at each location within the reactor, it is often inappropriate to simply use the average value of neutron flux measured by sensors surrounding the failed detector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-190482 Summary of the Invention [Problem to be solved by the invention]

[0005] A technique is provided for accurately estimating the measurement value of a failed measuring device installed inside a nuclear reactor when the measuring device fails.

[0006] The present disclosure provides a measurement value reconstruction method, reconstruction device, and program that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The reconstruction method disclosed herein is a method for reconstructing measurement values, in which, when a faulty measuring instrument among multiple measuring instruments installed in a reactor is designated as the faulty measuring instrument and a healthy measuring instrument located close to the faulty measuring instrument is designated as the proximate measuring instrument, the measurement value measured by the faulty measuring instrument at a first point in time before the failure is determined as the value obtained by multiplying the measurement value measured by the faulty measuring instrument at a first point in time before the failure by the rate of change in the neutron reaction rate of a specified material at the location of the faulty measuring instrument from the first point in time to a second point in time after the failure of the faulty measuring instrument and the ratio of the rate of change in the neutron reaction rate at the location of the proximate measuring instrument from the first point in time to the second point in time.

[0008] The reconstruction device of the present disclosure, when a faulty measuring instrument among multiple measuring instruments installed in a reactor is designated as the faulty measuring instrument and a healthy measuring instrument located close to the faulty measuring instrument is designated as a proximate measuring instrument, is equipped with a means for multiplying the measurement value measured by the faulty measuring instrument at a first point in time before the failure, the rate of change in the neutron reaction rate of a specified material at the location of the faulty measuring instrument from the first point in time to a second point in time after the failure of the faulty measuring instrument, and the ratio of the rate of change in the measurement value of the proximate measuring instrument from the first point in time to the rate of change in the neutron reaction rate at the location of the proximate measuring instrument from the first point in time to the second point in time, and setting the value obtained by the faulty measuring instrument at the second point in time.

[0009] The program disclosed herein causes a computer to execute a process in which, when a faulty measuring instrument among multiple measuring instruments installed in a nuclear reactor is designated as the faulty measuring instrument and a healthy measuring instrument located close to the faulty measuring instrument is designated as a proximate measuring instrument, the computer executes a process in which the measurement value measured by the faulty measuring instrument at a first point in time before the failure is determined as the measurement value at the second point in time by the faulty measuring instrument, multiplying the measurement value measured by the faulty measuring instrument at a first point in time before the failure by the rate of change in the neutron reaction rate of a specified material at the location of the faulty measuring instrument from the first point in time to a second point in time after the failure of the faulty measuring instrument, and the ratio of the rate of change in the neutron reaction rate at the location of the proximate measuring instrument from the first point in time to the second point in time. [Effects of the Invention]

[0010] The measurement value reconstruction method, reconstruction device, and program disclosed herein provide a technology for accurately estimating the measurement value of a failed measuring device installed inside a nuclear reactor when the measuring device fails. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram illustrating an example of a measurement system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the arrangement of detectors according to the embodiment. [Figure 3] FIG. 10 is a diagram illustrating an example of time-series measurement values ​​obtained by a detector according to the embodiment. [Figure 4] FIG. 10 is a diagram illustrating a method for reconstructing measurement values ​​according to an embodiment. [Figure 5] 10 is a flowchart illustrating an example of a measurement value reconstruction process according to the embodiment. [Figure 6] FIG. 1 illustrates an example of a hardware configuration of a failure detection device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Embodiment> The measurement value reconstruction method of the present disclosure will be described below with reference to FIGS. (System Configuration) FIG. 1 is a block diagram illustrating an example of a measurement system according to an embodiment. The measurement system 100 measures the power distribution of the reactor 1. The measurement system 100 includes n detectors 2-1, 2-2, ..., 2-n arranged at various locations in the reactor 1, a fault detection device 10, and a measurement device 20. The detectors 2-1 to 2-n are neutron detectors. The detectors 2-1 to 2-n measure the neutron flux of the reactor 1 and transmit the measured neutron flux to the fault detection device 10. Hereinafter, when it is not necessary to distinguish between the detectors 2-1 to 2-n, they may be referred to as detector 2.

[0013] The fault detection device 10 acquires the neutron flux measurement values ​​(current values ​​emitted by the detectors 2 in response to neutrons) measured by the detectors 2-1 to 2-n, determines whether each of the detectors 2-1 to 2-n is faulty, and outputs the neutron flux measurement values ​​measured by the detectors 2 for the detectors 2 that are not faulty to the measurement device 20. If a faulty detector 2 is found, the fault detection device 10 estimates the measurement value of the faulty detector 2 and outputs the estimated value to the measurement device 20 as the measurement value of the faulty detector 2. The measurement value of the faulty detector 2 is estimated using the measurement values ​​of healthy detectors 2 that are close to the faulty detector 2. The process of estimating the measurement value of the faulty detector 2 is called reconstruction.

[0014] The measuring device 20 calculates the power distribution of the reactor 1 by a known method from the neutron flux measured by the detectors 2-1 to 2-n. The calculated power distribution is used for monitoring and controlling the nuclear plant equipped with the reactor 1. Although the fault detection device 10 and the measuring device 20 are shown as separate devices in FIG. 1, the fault detection device 10 may be configured as a part of the measuring device 20.

[0015] (Configuration of the fault detection device) As shown in the figure, the fault detection device 10 includes a measurement value acquisition unit 11, a fault determination unit 12, a simulation unit 13, a reconstruction unit 14, an output unit 15, and a storage unit 16. The measurement value acquiring unit 11 acquires the neutron flux measured by the detectors 2-1 to 2-n. The measurement value acquiring unit 11 records the measurement values ​​of the neutron flux acquired from the detectors 2-1 to 2-n for each detector 2 in the storage unit 16.

[0016] The failure determination unit 12 determines whether the detector 2 has failed based on the measurement values ​​of the detector 2 recorded in the storage unit 16. For example, the failure determination unit 12 determines that the detector 2 has failed when the detector 2 stops transmitting measurement values ​​for a predetermined period of time or longer. Alternatively, the failure determination unit 12 may determine that the detector 2 has failed when the detector 2 transmits a signal indicating the occurrence of a failure or abnormality. Furthermore, the failure determination unit 12 may determine that the detector 2 has failed when the detector 2 transmits a value that deviates from the normal range. Alternatively, the failure determination unit 12 may determine that the detector 2 has failed when the change over time in the value transmitted from the detector 2 behaves abnormally (continuously increasing, fluctuating greatly, etc.). Furthermore, the failure determination unit 12 may determine that the detector 2 has failed when the detector 2 behaves differently from the measurement values ​​of adjacent detectors 2 or when a value that deviates by a predetermined value or more is measured.

[0017] The simulation unit 13 includes an analysis code for analyzing the state of the reactor 1. For example, the simulation unit 13 acquires information required for the analysis (such as sensor values) from an operating nuclear power plant and simulates the behavior inside the reactor 1 in real time using the analysis code. The simulation unit 13 analyzes the reaction rate (neutron reaction rate) of a neutron-sensitive material such as Rh (rhodium) at each time at the position where the detector 2 of the reactor 1 is arranged. Alternatively, the simulation unit 13 may provide the analysis code with operating conditions similar to those of the nuclear power plant and perform a simulation in advance to analyze the reaction rate of the neutron-sensitive material at each time at each position where the detector 2 is arranged.

[0018] When the failure determination unit 12 determines that the detector 2 has failed, the reconstruction unit 14 reconstructs the measurement values ​​of the failed detector 2. The reconstruction method will be described later. The output unit 15 outputs the measurement values ​​of the detectors 2-1 to 2-n acquired by the measurement acquisition unit 11 to the measurement device 20. For a detector 2 determined to be faulty, the output unit 15 outputs a reconstructed measurement value to the measurement device 20.

[0019] The storage unit 16 stores the measurement values ​​for each detector 2 acquired by the measurement value acquisition unit 11, the reconstructed measurement values, information defining the positional relationships of the detectors 2 arranged in the reactor 1, and the like. Alternatively, the storage unit 16 may store, for each detector 2, the range of nearby detectors 2 that can be used for reconstruction when the detector 2 fails, as well as the identification information of the detector 2. The range of detectors 2 that can be used for reconstruction refers to a range in which the MP ratios described below can be considered equivalent. This range may be determined, for example, based on the results of a calculation performed in advance, such as a simulation, to determine for each detector 2 in the reactor 1, the range of MP ratios that can be considered equivalent to that of the detector 2.

[0020] FIG. 2 shows an example of the arrangement of detectors 2 in a nuclear reactor 1. The left side of FIG. 2 is a schematic plan view of the nuclear reactor 1. A detector unit 3, which includes multiple detectors 2 arranged in the axial direction of the core, is located at the position indicated by "F." When individual distinctions between these detector units are not necessary, they will also be referred to as detector unit 3. Detector units 3-1 to 3-3 are located within the area enclosed by an oblong circle in the nuclear reactor 1. The right side of FIG. 2 is a cross-sectional view of the detector units 3-1 to 3-3. Detector unit 3-1 includes detectors 2-1 to 2-6. Similarly, detector unit 3-2 includes detectors 2-7 to 2-12, and detector unit 3-3 includes detectors 2-13 to 2-18. Here, we focus on detector 2-9 and explain how to reconstruct the measurement values ​​in the event of a failure of detector 2-9. In this example, the detectors 2 closest to detector 2-9 are, for example, detectors 2-3, 2-15, 2-8, and 2-10. The range of nearby detectors 2 can be set arbitrarily. For example, detectors 2-2, 2-4, 2-14, and 2-16 may be added to the detectors 2 adjacent to detector 2-9. However, the accuracy of the reconstructed measurements can be maintained by selecting detectors 2 located as close as possible as the adjacent detectors 2. In cases where a detector unit 3 exists only on one horizontal side, such as detector 2-1, and a detector 2 exists only on one axial side (bottom), detectors 2-2, 2-7, and 2-8 may be set as the adjacent detectors 2. If the range over which the MP ratios are equivalent is wide, more detectors 2 may be set as the adjacent detectors 2 to match that range. Conversely, even if nearby detectors exist, for example, if the MP ratio of detector 2-8 is not equivalent, only detectors 2-2 and 2-7 may be set as the adjacent detectors 2. Furthermore, in the reconstruction, it is not necessary to use all of the adjacent detectors 2. For example, if detector 2-9 fails, reconstruction may be performed using only horizontally adjacent detectors 2-3 and 2-15, or only vertically adjacent detectors 2-8 and 2-10, or the measurement values ​​of detector 2-9 may be reconstructed using only one of the adjacent detectors 2 (for example, detector 2-3). Note that the arrangement of detector units 3 shown in FIG. 2 is an example and is not limited to this.Furthermore, more or less than six detectors 2 may be arranged in one detector unit 3 .

[0021] FIG. 3 shows an example of time-series measurement values ​​and design values ​​for the target detector 2-9 and neighboring detectors 2-3, 2-8, 2-10, and 2-15. Specifically, the neutron flux measurement values ​​measured by each detector 2 at the T-2, T-1, T2, T+1, and T+2 measurements, along with the design values ​​at the locations where each detector 2 is located, are listed. The design values ​​are, for example, the reaction rates of the neutron-sensitive material at the locations of the detectors 2-3, 2-8, 2-9, 2-10, and 2-15 calculated by the simulation unit 13. The measurement value at the T-2 measurement for detector 2-9 is listed as M9(T-2), and the design value is listed as P9(T-2). Similarly, for other detectors, for example, for the neighboring detector 2-15, the measurement value at the Tth measurement by detector 2-15 is listed as M15(T), and the design value is listed as P15(T). 3, there are no failures in the nearby detectors 2-3, 2-8, 2-10, and 2-15, but the detector of interest 2-9 is determined to be faulty in the T+1 measurement, and the measured values ​​in the T+1 and T+2 measurements are "none." Next, the process of reconstructing the measured values ​​of detector 2-9 in the T+1 and T+2 measurements will be described with reference to FIG.

[0022] FIG. 4 is a diagram illustrating a method for reconstructing measurement values ​​according to this embodiment. In this embodiment, the measurement value M9(T+1) at the T+1st time of the detector 2-9 is estimated by multiplying the measurement value M9(T) before the failure by the "rate of change in the measurement value from before the failure to after the failure." Here, it may seem that the "rate of change in the measurement value from before the failure to after the failure" can be calculated, for example, from the rate of change from the Tth measurement value of the nearby detector 2-3 to the T+1th measurement value (M3(T+1) / M3(T)). However, the fuel state (fuel density, etc.) varies depending on the position within the reactor 1, and the change in neutron flux measured by the nearby detector 2-3 is only that at the position where the detector 2-3 is located. Therefore, the rate of change in the measurement value measured by the nearby detector 2-3 from before the failure to after the failure cannot be directly applied to the detector 2-9, even if the nearby detector 2-3 is located in a nearby position. Therefore, in this embodiment, the measurement value of the failed detector 2-9 is estimated by focusing on the rate of change in the reaction rate (design value) of the neutron-sensitive material calculated for the position of the detector 2-9, and utilizing the fact that the ratio of the rate of change in the reaction rate to the rate of change in the measured value is approximately equal within the range of nearby detectors 2. The ratio of the rate of change in the measured value to the rate of change in the reaction rate (design value) is called the MP ratio. Specifically, the estimated value of the measurement value of the detector 2-9 after the failure is obtained by multiplying the measurement value of the detector 2-9 before the failure by the rate of change in the design value at the position where the detector 2-9 is located from before the failure to after the failure and the MP ratio (rate of change in the measured value to the rate of change in the design value) for nearby detectors 2-3, etc.

[0023] For example, when reconstructing the measurement value of the detector 2-9 in the (T+1)th measurement using only the adjacent detector 2-3, the reconstruction unit 14 performs the reconstruction using the following equation (1). M9(T+1)=M9(T)×{(P9(T+1)÷P9(T))×((M3(T+1)÷M3(T))÷(P3(T+1)÷P3(T)))}...(1)

[0024] Similarly, when reconstructing the measurement value of the detector 2-9 in the T+2th measurement using only the adjacent detector 2-3, the reconstruction unit 14 performs the reconstruction using the following equation (2). M9(T+2)=M9(T)×{(P9(T+2)÷P9(T))×((M3(T+2)÷M3(T))÷(P3(T+2)÷P3(T)))}...(2)

[0025] That is, the measurement value of the detector 2-9 in the T+m-th measurement can be reconstructed by the following equations (3) and (4). M9(T+m)=M9(T)×{(P9(T+m)÷P9(T))×(MP ratio from Tth to Tmth times in one or more adjacent detectors 2)} (3)

[0026] MP ratio from Tth to Tmth times for one or more adjacent detectors 2 = {(average value of the measurement values ​​(T+m) of adjacent detectors 2 ÷ average value of the measurement values ​​(T) of adjacent detectors 2) ÷ (average value of the design values ​​(T+m) of adjacent detectors 2 ÷ average value of the design values ​​(T) of adjacent detectors 2)} (4)

[0027] For example, when four detectors 2-4, 2-8, 2-10, and 2-15 are used as detectors adjacent to the detector 2-9, the MP ratio is calculated by the following formula (5). MP ratio = {((M4(T+m)+M8(T+m)+M10(T+m)+M15(T+m))÷4)÷((M4(T)+M8(T)+M10(T)+M15(T))÷4)}÷ {((P4(T+m)+P8(T+m)+P10(T+m)+P15(T+m))÷4)÷((P4(T)+P8(T)+P10(T)+P15(T))÷4)}...(5)

[0028] When only the detectors 2-4 and 2-15 adjacent in the horizontal direction are used, the MP ratio is calculated by the following formula (5'). MP ratio = {((M4(T+m)+M15(T+m))÷2) / ((M4(T)+M15(T))÷2)} / {((P4(T+m)+P5(T+m))÷2) / ((P4(T)+P15(T))÷2)}...(5´)

[0029] When only the detectors 2-8 and 2-10 adjacent in the vertical direction (axial direction) are used, the MP ratio is calculated by the following formula (5''). MP ratio = {((M8(T+m)+M10(T+m))÷2) / ((M8(T)+M10(T))÷2)} / {((P8(T+m)+P10(T+m))÷2) / ((P8(T)+P10(T))÷2)}...(5´´)

[0030] It has been confirmed from past performance data that there is a strong correlation between the MP ratios of adjacent detectors 2. Using this property, the MP ratio, which is the ratio of the rate of change in the measured value to the rate of change in the reaction rate over a certain time period, is calculated in advance for each of multiple detectors 2. A group of detectors 2 (neighboring detectors 2 are grouped together) is created for detectors 2 that belong to a range in which the calculated MP ratio differences can be considered equivalent, and these groups are registered in the storage unit 16 as adjacent detectors 2. As described above, for detectors 2 that belong to a range in which the MP ratios are equivalent, the measured value after failure can be estimated by multiplying the measured value of the failed detector 2 before failure, the rate of change in the design value of the failed detector 2 from before failure to after failure, and the MP ratio of detectors 2 that belong to the same group. In other words, the MP ratio is defined as the "ratio of change in the measured value to the rate of change in the design value of the failed detector" as a correction amount for the discrepancy between the measured value and the design value. The range of detectors 2 in which this MP ratio is equivalent is identified for each detector 2, and detectors 2 located in the identified range are pre-set in the storage unit 16 as adjacent detectors 2. When a detector 2 fails, the measurement value of the failed detector 2 is reconstructed using the measurement value and design value of an adjacent detector 2 with an equivalent MP ratio. Conventionally, when a detector 2 fails, the measurement value of the failed detector 2 cannot be used for power distribution measurement until it is repaired or replaced. However, according to this embodiment, the measurement value of the failed detector 2 can be reconstructed and the result can be used for power distribution measurement. Furthermore, by using the reconstructed measurement value, the accuracy of the power distribution measurement can be improved compared to when there is no information on the neutron flux at the position of the failed detector 2.

[0031] (operation) Next, the operation of the fault detection device 10 will be described with reference to FIG. FIG. 5 is a flowchart illustrating an example of measurement value reconstruction processing according to the embodiment. As a premise, information defining the neighboring detectors 2 for each detector 2 is registered in the memory unit 16. In addition, the simulation unit 13 calculates (in advance or in parallel with the operation of the plant) the reaction rate (design value) of the neutron-sensitive material at every moment for each position where the detector 2 is arranged. The measurement value acquisition unit 11 acquires measurement values ​​from the multiple detectors 2 arranged in the reactor 1 (step S1). The measurement value acquisition unit 11 records the measurement value for each detector 2 in the memory unit 16. The memory unit 16 stores measurement values ​​for each detector 2 acquired over a certain period of time in the past. Next, the failure determination unit 12 determines whether each of the multiple detectors 2 has failed (step S2). For example, if a measurement value for detector 2-9 has not been acquired for a predetermined period of time, the failure determination unit 12 determines that detector 2-9 has failed. For example, if the measurement value for detector 2-9 has deviated from the normal range for a predetermined period of time, the failure determination unit 12 determines that detector 2-9 has failed. If there is no failed detector 2 (step S2; No), the output unit 15 outputs the neutron flux measurement values ​​for each detector 2 acquired by the measurement value acquisition unit 11 to the measurement device 20 (step S4).

[0032] If there is a faulty detector 2 (step S2; Yes), the fault determination unit 12 outputs identification information of the detector 2 determined to be faulty to the reconstruction unit 14. The reconstruction unit 14 reconstructs the measurement values ​​of the faulty detector 2 (step S3). The reconstruction unit 14 identifies detectors 2 adjacent to the faulty detector 2, and further extracts healthy detectors 2 (not determined to be faulty in step S2) from the identified detectors 2, and determines to use the measurement values ​​and design values ​​of the extracted detector 2 for reconstruction. Here, the faulty detector 2 is detector 2-9, the adjacent detector 2 is detector 2-3, the time when the neutron flux was last measured by detector 2-9 is t, and the estimated target time of the measurement values ​​is t+m. For example, if the measurement value and design value of detector 2-9 at time t are expressed as M9(t) and P9(t) as in the case of FIG. 4, the reconstruction unit 14 reconstructs the measurement value of detector 2-9 at time t+m using the following equation (1'): M9(t+m)=M9(t)×{(P9(t+m)÷P9(t))×((M3(t+m)÷M3(t))÷(P3(t+m)÷P3(t)))}...(1´) The reconstructing unit 14 records the reconstructed M9(t+m) in the storage unit 16.

[0033] Next, the output unit 15 reads the reconstructed values ​​for the detectors 2-9 from the storage unit 16, and for the other detectors 2, reads the measurement values ​​acquired by the measurement value acquisition unit 11 from the storage unit 16 and outputs the read measurement values ​​to the measurement device 20 (step S4). The measurement device 20 receives the neutron flux measurement values ​​transmitted from the fault detection device 10 and calculates the power distribution of the reactor 1.

[0034] (effect) As described above, according to this embodiment, if a detector 2 equipped in the reactor 1 fails, reconstruction can be performed to accurately estimate the measurement value of the failed detector 2. Regardless of whether a detector 2 fails or not, the power distribution of the reactor 1 can be calculated from the neutron flux measurement results at the positions of all detectors 2, thereby improving the measurement accuracy of the power distribution and preventing deviation from plant operation limits due to a detector 2 failure.

[0035] In the above embodiment, an example has been described in which the measurement value of the neutron detector 2 is reconstructed when it fails, but the reconstruction method of this embodiment can be applied to estimating measurement values ​​when other measuring equipment (in-core nuclear instrumentation) installed in the reactor 1 fails. Also, in the above embodiment, the measurement value last measured before the detector 2 failed and the rate of change from the design value were used during reconstruction, but if the time of failure is t, reconstruction may be performed using the measurement value at time t-1 or time t-2 and the rate of change from the design value instead of time t.

[0036] FIG. 6 is a diagram illustrating an example of a hardware configuration of the failure detection device 10. As shown in FIG. The computer 900 includes a CPU 901, a main memory device 902, an auxiliary memory device 903, an input / output interface 904, and a communication interface 905. The fault detection device 10 described above is implemented in the computer 900. The above-described functions are stored in the auxiliary memory device 903 in the form of a program. The CPU 901 reads the program from the auxiliary memory device 903, loads it into the main memory device 902, and executes the above-described processing in accordance with the program. The CPU 901 also allocates a storage area in the main memory device 902 in accordance with the program. The CPU 901 also allocates a storage area in the auxiliary memory device 903 for storing data being processed in accordance with the program.

[0037] A program for implementing all or part of the functions of the fault detection device 10 may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed to perform processing by each functional unit. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. If a WWW system is used, the term "computer system" also includes a homepage providing environment (or display environment). The term "computer-readable recording medium" refers to portable media such as CDs, DVDs, and USBs, as well as storage devices such as hard disks built into the computer system. If the program is distributed to the computer 900 via a communication line, the computer 900 may load the program into the main storage device 902 and execute the above-described processing. The program may be for implementing part of the above-described functions, or may be capable of implementing the above-described functions in combination with a program already stored in the computer system.

[0038] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as defined in the claims, as well as in the scope and spirit of the invention.

[0039] <Additional Notes> The measurement value reconstruction method, reconstruction device, and program described in the embodiments can be understood, for example, as follows.

[0040] (1) In the first aspect of the method for reconstructing measurement values, when a faulty measuring instrument among multiple measuring instruments installed in a reactor is designated as the faulty measuring instrument and a healthy measuring instrument located close to the faulty measuring instrument is designated as a proximate measuring instrument, the measurement value measured by the faulty measuring instrument at a first point in time before the failure is defined as the value obtained by multiplying the measurement value measured by the faulty measuring instrument at a first point in time before the failure by the rate of change in the neutron reaction rate of a specified material (neutron-sensitive material) at the location of the faulty measuring instrument from the first point in time to a second point in time after the failure of the faulty measuring instrument, and the ratio of the rate of change in the neutron reaction rate at the location of the proximate measuring instrument from the first point in time to the second point in time, and the value obtained by multiplying the rate of change in the measurement value of the proximate measuring instrument from the first point in time to the second point in time is defined as the measurement value measured by the faulty measuring instrument at the second point in time. This allows for accurate estimation of the measurement value of a measuring device installed in a nuclear reactor when the measuring device fails.

[0041] (2) A second aspect of the measurement value reconstruction method is the measurement value reconstruction method of (1), in which the measuring device is a neutron detector. This allows us to reconstruct (estimate) the neutron flux measured by a neutron detector in the event of a failure in that detector.

[0042] (3) A measurement value reconstruction method according to a third aspect is a measurement value reconstruction method of (1) to (2), wherein the nearby measuring device is selected from among the measuring devices such that the difference between a first MP ratio representing the ratio of the rate of change of the measurement value of the measuring device at a certain time to the rate of change of the neutron reaction rate at the position of the measuring device at the certain time, and a second MP ratio representing the ratio of the rate of change of the measurement value of the faulty measuring device at the certain time to the rate of change of the neutron reaction rate at the position of the faulty measuring device at the certain time, is within a predetermined range in which the first MP ratio and the second MP ratio can be considered equivalent. By using nearby measuring devices selected from this perspective, it is possible to reconstruct (estimate) the measurements of the failed measuring device.

[0043] (4) A fourth aspect of the measurement value reconstruction method is a measurement value reconstruction method according to any one of (1) to (3), wherein the proximate measuring device is positioned closest to the faulty measuring device in the axial direction of the reactor core. This allows the measurement values ​​of a failed measuring device to be reconstructed (estimated) with high accuracy.

[0044] (5) A fifth aspect of the measurement value reconstruction method is a measurement value reconstruction method according to any one of (1) to (4), wherein the proximate measuring device is positioned at the closest position horizontally to the faulty measuring device in the reactor. This allows the measurement values ​​of a failed measuring device to be reconstructed (estimated) with high accuracy.

[0045] (6) A method for reconstructing measurement values ​​according to the sixth aspect includes the steps of acquiring measurement values ​​of a plurality of the measuring instruments, determining whether or not there is a faulty measuring instrument among the plurality of the measuring instruments based on the measurement values, and, if it is determined that there is a faulty measuring instrument, estimating the measurement values ​​of the measuring instrument determined to be faulty by the measurement value reconstruction method of (1) to (5), assuming that the measuring instrument determined to be faulty is the faulty measuring instrument. This makes it possible to detect failures in the measuring equipment and reconstruct (estimate) the measurement values ​​of the measuring equipment.

[0046] (7) The reconstruction device of the seventh aspect, when a faulty measuring instrument among multiple measuring instruments installed in a reactor is designated as the faulty measuring instrument and a healthy measuring instrument located close to the faulty measuring instrument is designated as a proximate measuring instrument, is provided with a means for multiplying the measurement value measured by the faulty measuring instrument at a first point in time before the failure, the rate of change in the neutron reaction rate of a specified material at the position of the faulty measuring instrument from the first point in time to a second point in time after the failure of the faulty measuring instrument, and the ratio of the rate of change in the measurement value of the proximate measuring instrument from the first point in time to the rate of change in the neutron reaction rate at the position of the proximate measuring instrument from the first point in time to the second point in time, as the measurement value measured by the faulty measuring instrument at the second point in time.

[0047] (8) A program according to the eighth aspect causes a computer to execute a process in which, when a faulty measuring instrument among multiple measuring instruments installed in a reactor is designated as the faulty measuring instrument and a healthy measuring instrument located close to the faulty measuring instrument is designated as a proximate measuring instrument, the program executes a process in which the program determines the measurement value measured by the faulty measuring instrument at the second time point as a value obtained by multiplying the measurement value measured by the faulty measuring instrument at a first time point before the fault by the rate of change in the neutron reaction rate of a specified material at the location of the faulty measuring instrument from the first time point to a second time point after the failure of the faulty measuring instrument, and the ratio of the rate of change in the neutron reaction rate at the location of the proximate measuring instrument from the first time point to the second time point. [Explanation of symbols]

[0048] 1...nuclear reactor 2, 2-1 to 2-18 Detectors 3, 3-1, 3-2, 3-3... Detector unit 10. Fault detection device 11 Measurement acquisition section 12...Failure determination section 13 Simulation Section 14... Reconstruction section 15. Output section 16...Storage section 20. Measuring equipment 100... Measurement System 900···Computer 901 CPU 902...Main memory 903...Auxiliary storage device 904 Input / Output Interface 905···Communication Interface

Claims

1. When a faulty measuring device among a plurality of measuring devices installed in a nuclear reactor is defined as a faulty measuring device and a healthy measuring device adjacent to the faulty measuring device is defined as a nearby measuring device, a measurement value measured by the fault measurement device at a first time point before the fault; a rate of change in the neutron reaction rate of a predetermined material at the location of the faulty measurement device from the first time point to a second time point after the faulty measurement device has failed; a ratio of a rate of change of the neutron reaction rate at the position of the proximity measurement device from the first time point to the second time point to a rate of change of the measurement value of the proximity measurement device from the first time point to the second time point; The value obtained by multiplying by is set as the measurement value at the second time point by the fault measuring device. How to reconstruct measurements.

2. The measuring device is a neutron detector. The method of claim 1 .

3. The proximity measuring device is selected from among the measuring devices such that the difference between a first MP ratio, which represents the ratio of the rate of change of the measurement value of the measuring device at a certain time to the rate of change of the neutron reaction rate at the position of the measuring device at the certain time, and a second MP ratio, which represents the ratio of the rate of change of the measurement value of the faulty measuring device at the certain time to the rate of change of the neutron reaction rate at the position of the faulty measuring device at the certain time, is within a predetermined range in which the first MP ratio and the second MP ratio can be considered equivalent.

3. A method for reconstructing measurements according to claim 1 or claim 2.

4. The proximity measurement device is arranged at a position closest to the fault measurement device in the core axial direction of the reactor.

3. A method for reconstructing measurements according to claim 1 or claim 2.

5. The proximity measuring device is disposed at a position closest to the fault measuring device in the horizontal direction of the reactor.

3. A method for reconstructing measurements according to claim 1 or claim 2.

6. obtaining measurements of a plurality of said measurement devices; determining whether a faulty measuring device is present among the plurality of measuring devices based on the measurement values; When it is determined that a faulty measuring device exists, the faulty measuring device is treated as the faulty measuring device, and measurement values ​​of the faulty measuring device are estimated by the measurement value reconstruction method according to claim 1; A method for reconstructing measurements with

7. When a faulty measuring device among a plurality of measuring devices installed in a nuclear reactor is defined as a faulty measuring device and a healthy measuring device adjacent to the faulty measuring device is defined as a nearby measuring device, a measurement value measured by the fault measurement device at a first time point before the fault; a rate of change in the neutron reaction rate of a predetermined material at the location of the faulty measurement device from the first time point to a second time point after the faulty measurement device has failed; a ratio of a rate of change of the neutron reaction rate at the position of the proximity measurement device from the first time point to the second time point to a rate of change of the measurement value of the proximity measurement device from the first time point to the second time point; a means for multiplying the value by the value obtained by multiplying the value by the value obtained by the fault measuring device at the second time point; A reconstruction device comprising:

8. On the computer, When a faulty measuring device among a plurality of measuring devices installed in a nuclear reactor is defined as a faulty measuring device and a healthy measuring device adjacent to the faulty measuring device is defined as a nearby measuring device, a measurement value measured by the fault measurement device at a first time point before the fault; a rate of change in the neutron reaction rate of a predetermined material at the location of the faulty measurement device from the first time point to a second time point after the faulty measurement device has failed; a ratio of a rate of change of the neutron reaction rate at the position of the proximity measurement device from the first time point to the second time point to a rate of change of the measurement value of the proximity measurement device from the first time point to the second time point; a process of multiplying the value obtained by multiplying the value by the fault measuring device and setting the result as the measurement value at the second time point; A program that executes the following.

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