Nuclear equipment

Abstract

The purpose of the present invention is to obtain a nuclear instrumentation device that can measure minute currents with a high dynamic range with higher precision than in the related art.　A signal processing unit (100) of a nuclear instrumentation device comprises: an IV conversion unit (110) that has IV conversion circuits each corresponding to a respective range and converts the current input from a neutron detector into voltage; an amplifying unit (120) that amplifies the voltage and outputs the amplified voltage as an output voltage (VO); a calculation unit (150) that determines the range on the basis of the output voltage, calculates a current value from the output voltage, and outputs the calculated value as a measured value (X); a range switching unit (130) that has switches each corresponding to a respective range and switches the range according to a command from the calculation unit (150); and a charging / discharging unit (140) that performs charging / discharging processing of discharging an electric charge accumulated in a capacitor corresponding to a switching source range and charging a capacitor corresponding to a switching destination range when the range is switched.

Description

Technical Field

[0001] This application relates to a nuclear instrumentation device.

Background Art

[0002] In the monitoring of a nuclear reactor, neutrons emitted from the nuclear reactor are received by a detector, and the current signal output from the detector is measured by a nuclear instrumentation device. The nuclear instrumentation device outputs the measured value of the current to an upper monitoring and control device, and the monitoring and control device performs control such as output based on the situation of the nuclear reactor. In recent years, while the miniaturization of nuclear reactors has been progressing, the current value measured by the nuclear instrumentation device may be less than or equal to μA, and there is a demand for highly accurate measurement even for currents that are more minute and have a higher dynamic range than before.

[0003] For highly accurate measurement of a current with a high dynamic range, it is necessary to perform measurement within an optimal range according to the magnitude of the measured value. However, there is a problem that switching the range causes fluctuations in the measured value. Therefore, after determining the optimal range, when switching the range to the optimal range, there is a device that holds the signal at a constant value for a time that is an integer multiple of the time constant of the circuit (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the technique of Patent Document 1 described above has a problem that there is a possibility that accurate measurement cannot be performed when fluctuations in the input signal that is the measurement target occur in a short time. Specifically, when fluctuations in the input signal occur in a time shorter than the time constant of the circuit, fluctuations during the period when the signal is held at a constant value cannot be measured.

[0006] This invention was made to solve the problems described above, and aims to provide a nuclear instrumentation device that enables more accurate measurements than conventional devices for minute currents with a high dynamic range. [Means for solving the problem]

[0007] The nuclear instrumentation device disclosed herein is a nuclear instrumentation device having a plurality of ranges, including a first range and a second range, and having a current-voltage conversion circuit corresponding to each range, each having capacitors and resistors connected in parallel, a current-voltage conversion unit that converts a current input from a neutron detector into a voltage, an amplification unit that amplifies the voltage and outputs it as an output voltage, a range switching unit that has a switch to turn on and off the current-voltage conversion circuit corresponding to the second range, and switches the range by changing the current-voltage conversion circuit that is turned on or the combination of current-voltage conversion circuits that are turned on, a calculation unit that determines the range to be used for measuring the current as the measurement range based on the output voltage, causes the range switching unit to switch the range to the measurement range, calculates the current value of the current from the output voltage and outputs the obtained result, and a charge-discharge unit that performs a charge-discharge process when the range is switched, by discharging the charge stored in the capacitor corresponding to the range before switching and charging the capacitor corresponding to the range after switching with the charge. It is something that is provided. [Effects of the Invention]

[0008] The nuclear instrumentation device disclosed herein can perform measurements with higher accuracy than conventional methods for minute currents with a high dynamic range. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating the monitoring and control of a nuclear reactor according to Embodiment 1. [Figure 2] This figure shows a schematic representation of the reactor core and detector assemblies installed inside and outside the reactor core according to Embodiment 1. [Figure 3]This diagram shows the configuration of the in-furnace fixed detector assembly according to Embodiment 1. [Figure 4] This is a diagram explaining neutron detection. [Figure 5] This is a schematic diagram showing the signal processing unit of the nuclear instrumentation system in Embodiment 1. [Figure 6] This is a diagram showing the signal processing unit according to Embodiment 1, and a diagram illustrating the detailed configuration of the charging and discharging unit according to Embodiment 1. [Figure 7] This is a block diagram showing the calculation unit according to Embodiment 1. [Figure 8] This figure shows an example of the hardware configuration of the arithmetic unit according to Embodiment 1. [Figure 9] This is a flowchart illustrating the operation of the signal processing unit of the nuclear instrumentation system in Embodiment 1. [Figure 10] This is a flowchart showing the range switching process according to Embodiment 1. [Figure 11A] This diagram illustrates the range switching process according to Embodiment 1, and shows the state where the range is set to range 1. [Figure 11B] This diagram illustrates the range switching process according to Embodiment 1, and shows the circuit switch for range 2 in the ON state. [Figure 11C] This diagram illustrates the range switching process according to Embodiment 1, and shows the circuit for range 1 with the switch turned off. [Figure 11D] This diagram illustrates the range switching process according to Embodiment 1, and shows the state in which charging is being performed by the charging / discharging unit. [Figure 11E] This diagram illustrates the range switching process according to Embodiment 1, and shows the state after charging by the charging / discharging unit has been completed. [Figure 12A] This diagram shows the difference in amplifier output voltage during range switching, with and without charging and discharging by the charging / discharging unit. [Figure 12B] This figure shows the difference in measured values ​​during range switching between cases with and without charging / discharging by the charging / discharging unit, and with conventional technology. [Figure 13] It is a flowchart showing another example of the range switching process according to Embodiment 1. [Figure 14] It is a configuration diagram showing a first modification example of the signal processing unit according to Embodiment 1. [Figure 15] It is a configuration diagram showing a second modification example of the signal processing unit according to Embodiment 1. [Figure 16] It is a configuration diagram showing the signal processing unit according to Embodiment 2. [Figure 17] It is a diagram showing the charge amount table of the compensation capacitor according to Embodiment 2. [Figure 18] It is a flowchart showing the range switching process according to Embodiment 2. [Figure 19] It is a configuration diagram showing the learning unit according to Embodiment 3. [Figure 20] It is a configuration diagram showing the inference unit according to Embodiment 3. [Figure 21] It is a flowchart showing the operation of the signal processing unit of the nuclear instrumentation device in Embodiment 3.

MODE FOR CARRYING OUT THE INVENTION

[0010] Embodiment 1. Embodiment 1 will be described with reference to Figures 1 to 13. Figure 1 is a schematic diagram illustrating the monitoring and control of a nuclear reactor according to Embodiment 1. The monitoring and control device 921 monitors and controls the conditions inside the containment vessel, and in order to understand the conditions inside the containment vessel, it acquires information such as the dose rate of neutrons emitted by the reactor core 901 located inside the containment vessel. The neutron dose rate is calculated based on the current value of the current signal CI output by various neutron detectors (not shown in Figure 1) installed inside the containment vessel in conjunction with the detection of neutrons. The current signal CI output by the neutron detectors is sent outside the containment vessel via electrical penetration that connects the inside and outside of the containment vessel, and the current value is measured by the nuclear instrumentation device 910 outside the containment vessel. The current value measured by the nuclear instrumentation device 910 is transmitted as the measured value X to the monitoring and control device 921 via a higher-level interface (not shown). Control commands Y from the monitoring and control device 921 to the nuclear instrumentation device 910 are also sent via this higher-level interface.

[0011] The nuclear instrumentation system 910 includes an external nuclear instrumentation system 911 and an internal nuclear instrumentation system 912, each with a different corresponding neutron detector, but both have one or more signal processing units 100 inside. The signal processing unit 100 receives a current signal CI as input and outputs a measured value X. Details of the signal processing unit 100 will be described later.

[0012] Figure 2 is a schematic diagram showing the reactor core and detector assemblies mounted inside and outside the reactor core according to Embodiment 1, and Figure 3 is a diagram showing the configuration of the in-core fixed detector assembly according to Embodiment 1. The reactor core 901 has the in-core fixed detector assembly 902 fixed inside, and the source region detector assembly 903 and wide-area detector assembly 904 fixed to the outer periphery. Inside the in-core fixed detector assembly 902, as shown in Figure 3, for example, five neutron detectors 902a are arranged in series. Similarly, the source region detector assembly 903 and wide-area detector assembly 904 are each provided with neutron detectors 903a and neutron detectors 904a inside.

[0013] The neutron detector 902a of the in-reactor fixed detector assembly 902 corresponds to the in-reactor nuclear instrumentation system 912, while the neutron detector 903a of the source region detector assembly 903 and the neutron detector 904a of the wide-area detector assembly 904 correspond to the out-reactor nuclear instrumentation system 911, respectively.

[0014] Figure 4 illustrates neutron detection. While Figure 4 describes neutron detector 902a, the process is similar for neutron detection using neutron detectors 903a and 904a. When neutron detector 902a receives neutrons n emitted from the reactor core 901, some electrons in the material constituting the neutron detector 902a are ejected, causing a current to flow. This current is transmitted as a current signal CI to the in-reactor nuclear instrumentation system 912 (referred to as nuclear instrumentation system in Figure 4; in the case of neutron detectors 903a and 904a, it is called the out-reactor nuclear instrumentation system 911). Upon receiving the current signal CI, the in-reactor nuclear instrumentation system 912 measures the current value of the current signal CI and outputs it as the measured value X.

[0015] The measurement of the current value of the current signal CI is performed by the signal processing unit 100 mounted on the extra-reactor nuclear instrumentation system 911 and the extra-reactor nuclear instrumentation system 912. Figure 5 is a schematic diagram showing the signal processing unit of the nuclear instrumentation system in Embodiment 1. The signal processing unit 100 measures the current value of the current signal CI in a range determined to be optimal according to the current signal CI input via the input terminal (not shown), and performs current-to-voltage conversion (hereinafter referred to as IV conversion). Specifically, it comprises an IV conversion unit 110 (corresponding to the "current-voltage conversion unit") that converts a current signal CI into a voltage signal, an amplification unit 120 that amplifies the voltage converted by the IV conversion unit 110 with a gain corresponding to the range and outputs an output voltage VO, a range switching unit 130 connected in series with the IV conversion unit 110 that switches the range in measurement, a charge / discharge unit 140 connected to the IV conversion unit 110 that performs charge / discharge processing of a capacitor when the range is switched, and a calculation unit 150 that receives the output voltage VO as input, calculates and outputs a measured value X from the output voltage VO, and also gives a range switching instruction to the range switching unit 130 and a charge / discharge instruction to the charge / discharge unit 140.

[0016] The IV conversion unit 110 consists of IV conversion circuits (corresponding to "current-voltage conversion circuits") connected in parallel, each corresponding to a range from range 1 to range n (where n is an integer of 2 or more). Each range's IV conversion circuit is provided with resistors and capacitors connected in parallel to each other. Hereafter, the resistors and capacitors corresponding to each range will be referred to as resistor R1, resistor R2... resistor Rn and capacitor C1, capacitor C2... capacitor Cn. In Figure 5, IV conversion circuit A1 is the IV conversion circuit corresponding to range 1, and IV conversion circuit An is the IV conversion circuit corresponding to range n. The IV conversion circuits from range 2 to range (n-1) are omitted from the description. Furthermore, the resistance values ​​of resistors R1, R2,... resistor Rn are assumed to be R1, R2,... Rn, respectively, and the capacitances of capacitors C1, C2,... capacitor Cn are assumed to be C1, C2, and Cn, respectively. In Embodiment 1, a larger range is used as the current value of the object being measured increases, and a smaller range corresponds to a larger resistance value of the corresponding resistor.

[0017] For the purposes of this explanation, the input terminal side of the signal processing unit 100 (left side in Figure 5) will be referred to as the input side, and the opposite side of the input side as the output side. Since the non-inverting input terminal of the amplifier 121 is connected to ground potential, the input side of the IV conversion unit 110 is virtually grounded.

[0018] Furthermore, in Embodiment 1, the circuit constants are set such that the product of the resistance value and capacitance in each range is equal. That is, in Embodiment 1, the following equation (1) holds true. R1 × C1 = R2 × C2 = ... = Rn × Cn ... (1) Equation (1) holds true, which means that the time constants of the IV conversion circuits for each range are equal.

[0019] The amplification unit 120 includes an amplifier 121. The inverting input terminal of the amplifier 121 is connected to the input terminal of the signal processing unit 100 and to the input side of the IV conversion unit 110 (the input side of the IV conversion circuit for each range). The non-inverting input terminal of the amplifier 121 is connected to ground potential. The output terminal of the amplifier 121 is connected to the calculation unit 150. The output terminal of the amplifier 121 is also connected to the inverting input terminal of the amplifier 121 via the range switching unit 130 and the IV conversion unit 110. More specifically, a feedback circuit is formed by the switches of the range switching unit 130 and the IV conversion circuits of the IV conversion unit 110, corresponding to each range.

[0020] The range switching unit 130 is configured by connecting switches corresponding to the IV conversion circuits of each range in parallel. The input side of the range switching unit 130 is connected to the output side of the IV conversion unit 110. The output side of the range switching unit 130 is connected to the output terminal of the amplifier 121 and the calculation unit 150.

[0021] As described above, each range's IV conversion circuit is equipped with resistors and capacitors connected in parallel to each other. In the range switching section 130, switches corresponding to the resistors and capacitors are also provided in parallel. In Figure 5, the switches corresponding to the resistors (resistors R1, R2, ... Rn) of each range are designated as switches SR1, SR2, ... SRn, respectively. The input sides of switches SR1, SR2, ... SRn are connected to the output sides of resistors R1, R2, ... Rn. In addition, the switches corresponding to the capacitors (capacitors C1, C2, ... Cn) of each range are designated as switches SC1, SC2, ... SCn, respectively. The input sides of switches SC1, SC2, ... SCn are connected to the output sides of capacitors C1, C2, ... Cn.

[0022] The output sides of switches SR1, SR2, ..., SRn, and SC1, SC2, ..., SCn are connected to the output terminals of amplifier 121 and the input side of calculation unit 150. Furthermore, the on / off states of switches SR1, SR2, ..., SRn, and SC1, SC2, ..., SCn are controlled by the calculation unit 150.

[0023] The charge / discharge unit 140 is connected to the output side of the capacitors (capacitor C1, capacitor C2, ... capacitor Cn) of each range in the IV conversion unit 110. The operation of the charge / discharge unit 140 is controlled by the calculation unit 150.

[0024] The charging and discharging section 140 will be described in detail. For simplicity, only ranges 1 and 2 are shown in this explanation, but the same applies if there are ranges 3 and above. Figure 6 is a configuration diagram showing the signal processing unit according to Embodiment 1, and is a diagram illustrating the detailed configuration of the charging and discharging section according to Embodiment 1. As described above, in Embodiment 1, the circuit constants in the IV conversion section 110 are set so that the product of the resistance value and capacitance of each range is equal. When this condition is met, the capacitors of each range in the IV conversion section 110 also become part of the charging and discharging section 140. In this case, the charging and discharging section 140 can be realized with a simple combination of switches. The charging and discharging section 140 is provided with switches SW1 and SW2 connected in parallel. The input side of switch SW1 is connected to the output side of capacitor C1, that is, between capacitor C1 and switch SC1. The input side of switch SW2 is connected to the output side of capacitor C2, that is, between capacitor C2 and switch SC2. The output sides of switches SW1 and SW2 are connected to ground potential. Switches SW1 and SW2 correspond to the second switch.

[0025] Next, the calculation unit 150 will be described. Figure 7 is a block diagram showing the calculation unit according to Embodiment 1. The calculation unit 150 performs various calculations in the signal processing unit 100, determines the range used for measurement, i.e., the measurement range, and controls various switches. As shown in Figure 7, the calculation unit 150 includes an input unit 151 that accepts inputs such as the output voltage VO of the amplifier 121, a storage unit 152 that stores threshold data used to determine the measurement range and calculation formula data for calculating the output voltage VO into a current value, an A / D conversion unit 153 that performs A / D conversion (analog-to-digital conversion) on the output voltage VO, a range determination unit 154 that determines the optimal range for measurement as the measurement range based on the output voltage VO value converted into a digital value, a range switching instruction unit 155 that outputs an instruction to the range switching unit 130 so that the range becomes the measurement range when the current range is different from the measurement range, and also outputs an instruction to the charge / discharge unit for charge / discharge processing associated with the range switching, a current value calculation unit 156 that calculates the current value from the output voltage VO value converted into a digital value using a calculation formula determined for each range and generates a current signal, a filter unit 157 that filters the current signal generated by the current value calculation unit 156 to remove noise, and a measurement value output unit 158 ​​that outputs the current value of the noise-removed current signal as the measurement value X.

[0026] Figure 8 shows an example of the hardware configuration of the arithmetic unit according to Embodiment 1. The arithmetic unit 150 mainly consists of a processor 91, a memory 92 as main memory, and an auxiliary storage device 93. The processor 91 is composed of, for example, a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), or an FPGA (Field Programmable Gate Array). The memory 92 is composed of a volatile storage device such as random access memory, and the auxiliary storage device 93 is composed of a non-volatile storage device such as flash memory or a hard disk. The auxiliary storage device 93 stores a predetermined program to be executed by the processor 91, and the processor 91 reads and executes this program as appropriate to perform various arithmetic processing. At this time, the predetermined program is temporarily stored in the memory 92 from the auxiliary storage device 93, and the processor 91 reads the program from the memory 92. The arithmetic processing by each functional unit shown in Figure 1 is realized by the processor 91 executing the predetermined program as described above. The results of the calculations performed by the processor 91 are temporarily stored in the memory 92, and then stored in the auxiliary storage device 93 according to the purpose of the calculations performed.

[0027] Furthermore, the memory 92 and auxiliary storage device 93 realize the storage of various data by the storage unit 152 described above. The arithmetic unit 150 also includes an input circuit 94 that receives various inputs to the arithmetic unit 150 and an output circuit 95 that realizes the output from the arithmetic unit 150.

[0028] Next, the operation will be described. Figure 9 is a flowchart showing the operation of the signal processing unit of the nuclear instrumentation system in Embodiment 1. First, the current signal CI from the neutron detector 902a is input (step ST001).

[0029] Next, the IV conversion unit 110 converts the current signal CI into a voltage signal (step ST002). More specifically, the IV conversion circuit of the ON range within the IV conversion unit 110 converts the current signal CI into a voltage signal. The "ON range IV conversion circuit" refers to the IV conversion circuit of the range switching unit 130 whose corresponding range switch is set to ON. The voltage signal converted from the current signal CI is controlled by the amplification unit 120 so as to maintain virtual ground, output as an output voltage VO, and input to the calculation unit 150.

[0030] Next, the output voltage VO is converted from analog to digital (step ST003).

[0031] Next, the optimal range is determined as the measurement range (step ST004). The determined measurement range is then compared with the current range to determine whether a range switch is necessary (step ST005). If a range switch is not necessary, it is determined that the optimal range is set, and the process proceeds to step ST007.

[0032] If a range change is necessary, the range change process is performed (step ST006), and after the range change, the process returns to step ST002. Details of the range change process will be described later.

[0033] If it is determined that the optimal range is set, the current value is calculated from the output voltage VO (step ST007). Next, the current signal generated as a result of the current value calculation is filtered and the obtained measured value X is output (step ST008).

[0034] The range switching process will now be explained. Figure 10 is a flowchart showing the range switching process according to Embodiment 1. As described above, the signal processing unit 100 measures the current value using a measurement range determined according to the output voltage VO of the amplifier 121, and the range used for measurement is switched to the above measurement range as appropriate. Here, there are several ways to set the range to a specific measurement range. For example, one method is to realize the measurement range by turning on only one IV conversion circuit, and another method is to realize the measurement range by combining multiple IV conversion circuits to be turned on. In either case, it is sufficient to set a calculation formula for calculating the current value from the output voltage VO according to the constants of the IV conversion circuits (or combinations thereof) to be turned on. First, the case in which only one IV conversion circuit is turned on will be explained. In this method, the range before switching is called the source range, and the range after switching is called the destination range, and the connection of the IV conversion circuit corresponding to the source range is switched to the connection of the IV conversion circuit corresponding to the destination range. First, the source range is called range 1 and the destination range is called range 2, and this will be explained using Figures 11A to 11E.

[0035] In the initial state, the setting is to range 1, so as shown in Figure 11A, switches SC1 and SR1 corresponding to the IV conversion circuit of range 1 are ON, and switches SC2 and SR2 corresponding to the IV conversion circuit of range 2 are OFF. Also, switches SW1 and SW2 of the charge / discharge unit 140 are OFF.

[0036] In the range switching process, the IV conversion circuit of the target range is first turned on (step ST601). As shown in Figure 11B, switches SC2 and SR2, which correspond to the IV conversion circuit of range 2, are turned on, and both the IV conversion circuit of range 1 and the IV conversion circuit of range 2 are turned on.

[0037] Next, the IV conversion circuit for the source range is turned off (step ST602). As shown in Figure 11C, switches SC1 and SR1, which correspond to the IV conversion circuit for range 1, are turned off. Now, only the IV conversion circuit for range 2 is turned on.

[0038] Next, discharge is performed from the capacitor of the source range to the capacitor of the destination range (step ST603, charge / discharge process). As shown in Figure 11D, in the charge / discharge unit 140, switch SW1 corresponding to the source range (range 1) is turned on. This creates a path where the ground of the charge / discharge unit 140 → switch SW1 → capacitor C1 → capacitor C2 → output terminal of amplifier 121 → ground potential and current flow of the amplification unit 120. As a result, the charge stored in capacitor C1 is discharged from capacitor C1 to capacitor C2, and capacitor C2 is charged. Furthermore, as described above, in Embodiment 1, the time constants of the IV conversion circuits for each range are equal, so the discharge from capacitor C1 to capacitor C2 charges capacitor C2 without excess or deficiency.

[0039] Next, the charging and discharging process is completed by making the output side of the capacitor of the source range high impedance (step ST604). As shown in Figure 11E, switch SW1, which corresponds to range 1, is off. Since switch SW1 is connected to the output side of capacitor C1, the output side of capacitor C1, which corresponds to range 1 (the source range), is made high impedance. This completes the charging and discharging process. The range switching process is also completed, and measurements are then performed using range 2. In this explanation, we described switching from range 1 to range 2, and therefore the charging and discharging process was performed by operating switch SW1. When switching from range 2 to range 1, range 2 becomes the source range, so the charging and discharging process is performed by operating switch SW2. In other words, during the charging and discharging process, the charging and discharging process and its completion are achieved by operating the switch in the charging and discharging unit 140 that corresponds to the range in which the IV conversion circuit is turned off when the range is switched.

[0040] Next, the effects of Embodiment 1 will be explained. Figure 12A shows the difference in the output voltage of the amplifier during range switching with and without charging and discharging by the charging / discharging unit, and Figure 12B shows the difference in measured values ​​during range switching with and without charging and discharging by the charging / discharging unit, and with the conventional technology. In Figures 12A and 12B, the horizontal axis represents time, and range switching occurs at times t1 and t2. Figures 12A and 12B show a situation where the current value of the object being measured is gradually increased, and the range is also gradually increased.

[0041] As shown in Figure 12A, in the absence of charge / discharge processing (dotted line), there is a delay in the decrease of the output voltage VO of the amplifier 120 during range switching. More specifically, in the absence of charge / discharge processing, the convergence of the output voltage VO during range switching takes time constants determined by the capacitor charging time. Here, "capacitor charging time" is the charging time of the capacitor in the target range, and is determined by "the product of the resistance value of the resistor in the target range and the capacitance of the capacitor in the target range." Note that, from equation (1), this value is also the product of the resistance value of the resistor in the source range and the capacitance of the capacitor in the source range. In the presence of charge / discharge processing (solid line), the output voltage VO decreases rapidly. Strictly speaking, even with charge / discharge processing, it takes time for the output voltage VO to converge, but the "capacitor charging time" that determines this time is "the product of the output impedance of the charge / discharge section and the capacitance of the capacitor in the target range," making it possible to shorten the convergence time of the output voltage VO.

[0042] As shown in Figure 12B, the same applies to the measured value X. That is, when switching ranges, the measured value X temporarily rises, and if there is no charge / discharge process (dotted line), it takes time to converge, but if there is a charge / discharge process (solid line), it can converge in a short time. Note that Figure 12B shows an example where the measured value X is increasing, so the measured value X rises when switching ranges, but if the measured value X is decreasing, the measured value X falls when switching ranges. However, this does not affect the effect of Embodiment 1.

[0043] The rise time of the measured value X shown in Figure 12B indicates the deviation from the true value during range switching. Therefore, the smaller the magnitude of the deviation and the shorter the time it takes for the deviation to occur, the higher the measurement accuracy. In Figure 12B, the conventional technology (the technology described in Patent Document 1) is also shown with a dotted line, and it can be seen that even in the conventional technology, a temporary deviation from the true value occurs during range switching. In Embodiment 1, the charging and discharging process during range switching improves the measurement accuracy during range switching and, consequently, throughout the entire measurement. It is common to increase the time constant of the circuit to improve measurement accuracy, but as mentioned above, if the time constant of the circuit is large, the output voltage VO and the measured value X take a long time to converge during range switching. In other words, simply increasing the time constant of the circuit makes it difficult to perform high-precision measurements for minute currents with a high dynamic range.

[0044] In Embodiment 1, by configuring the system to perform charge and discharge processing when switching ranges, the convergence time of the measured value X during range switching is made dependent on the output impedance of the charge and discharge section. This allows for a larger time constant for the IV conversion circuit in each range while shortening the convergence time of the measured value X during range switching, thus enabling highly accurate measurement even for minute currents with a high dynamic range.

[0045] In Embodiment 1, it is assumed that equation (1) above holds true. When equation (1) holds true, charging and discharging occur without excess or deficiency between the capacitor of the source range and the capacitor of the destination range, and the ideal effect can be obtained. However, even if equation (1) does not hold true, discharge occurs from the capacitor of the source range to the capacitor of the destination range, so a similar effect can be obtained, albeit to a limited extent.

[0046] Next, another example of the range switching process according to Embodiment 1 will be described based on Figure 13. In this example, the measurement range is realized by combining multiple IV conversion circuits that are turned on. Specifically, measurement by range 1 is realized by turning on only the IV conversion circuit of range 1, and measurement by range 2 is realized by turning on the IV conversion circuits of range 1 and range 2, respectively. Although "range 2" in the examples in Figure 10 and Figures 11A to 11E is different from "range 2" in the example in Figure 13, as described above, the calculation unit 150 sets the formula used to calculate the current value to the optimal one, so the same result can be obtained. For example, if the calculation formula is a linear formula, the coefficient and constant term of the first order should be set to values ​​corresponding to the range. These values ​​are determined by the constants (resistance value, capacitance) of the IV conversion circuit corresponding to each range. As will be described later, in the example in Figure 13, the IV conversion circuit of range 1 is always on, and the range is switched by whether or not to turn on additional IV conversion circuits from range 2 onwards. Note that everything except the range switching process is the same as in Figure 9, so only the range switching process will be explained.

[0047] First, it is determined whether to raise or lower the range (step ST600). If the range is raised, the additional IV conversion circuit (the IV conversion circuit for range 2 if raising from range 1 to range 2) is turned on (step ST601A). That is, switch SC2 corresponding to capacitor C2 and switch SR2 corresponding to resistor R2 are turned on. If the range is lowered, the additional IV conversion circuit that was turned on (the IV conversion circuit for range 2 if lowering from range 2 to range 1) is turned off (step ST601B). That is, switch SC2 corresponding to capacitor C2 and switch SR2 corresponding to resistor R2 are turned off.

[0048] When increasing the range, the process ends when the additional IV conversion circuit is turned on. When switches SC2 and SR2 are turned on to connect from range 1 to range 2, a portion of the charge currently stored in capacitor C1 is transferred to capacitor C2, and the charge is distributed according to the ratio of C1 and C2. Therefore, operation of switch SW1 for the charging and discharging process and its completion is unnecessary. When lowering the range, the additional IV conversion circuit that is turned on must be turned off, and the charge / discharge process (step ST602B) and the completion of the charge / discharge process (step ST603B) must be completed. When lowering from range 2 to range 1, switches SC2 and SR2, which are turned on, are turned off, and switch SW2 is turned on to discharge the charge from capacitor C2 and charge capacitor C1. Also, by turning off switch SW2, the output side of the capacitor in range 2 is made high impedance, and the charge / discharge process is completed.

[0049] Thus, when measurement in range 2 is achieved by turning on the IV conversion circuits for range 1 and range 2 respectively, the IV conversion circuit for range 1 is always on, and no switch operation is required for charging and discharging when switching from range 1 to range 2. For this reason, switches SC1, SR1, and SW1, which correspond to range 1, can be omitted. This is because switches SC1 and SR1 are always on, and switch SW1 is always off. As shown in the examples in Figure 10 and Figure 13, depending on the method used to realize the measurement range, the IV conversion circuit for range 1 may or may not need to be switched on or off. On the other hand, the IV conversion circuits for ranges 2 and above are switched on or off regardless of the method used. In other words, for ranges 2 and above, a switch to switch the corresponding IV conversion circuit on or off is essential. Therefore, range 1 corresponds to the first range, and ranges 2 and above correspond to the second range.

[0050] According to Embodiment 1, it is possible to perform measurements with higher accuracy than conventional methods for minute currents with a high dynamic range. More specifically, the signal processing unit of the nuclear instrumentation system has an IV conversion circuit corresponding to each range, comprising: an IV conversion unit that converts the current input from the neutron detector into a voltage; an amplification unit that amplifies the voltage converted by the IV conversion unit and outputs it as an output voltage; a calculation unit that determines the range based on the output voltage, calculates the current value from the output voltage, and outputs it as a measured value; a range switching unit that has switches corresponding to each range and switches the range according to a command from the calculation unit; and a charge / discharge unit that performs a charge / discharge process that discharges the charge stored in the capacitor corresponding to the source range when the range is switched, and charges the capacitor corresponding to the destination range with this charge. The charge / discharge process during range switching shortens the convergence time of the measured value during range switching, making it possible to perform high-precision measurements even for minute currents with a high dynamic range.

[0051] Therefore, continuous measurement becomes possible even for minute currents, which were previously impractical to measure using automatic range switching, enabling continuous monitoring of reactors from low to high power. Furthermore, by suppressing fluctuations in measured values ​​during range switching, it helps to prevent deviations from safety regulations and false trips due to misassessment of the reactor's power distribution.

[0052] Next, a first modification of Embodiment 1 will be described. Figure 14 is a configuration diagram showing a first modification of the signal processing unit according to Embodiment 1. Note that equation (1) above also holds true in the first modification. For this reason, in the signal processing unit 101, the capacitors of each range of the IV conversion unit 1101 also become part of the charge / discharge unit 1401. Although Figure 14 shows the case with two ranges, the same applies to cases with three or more ranges. The configuration of the IV conversion unit 1101, range switching unit 1301, and charge / discharge unit 1401 of the signal processing unit 101 differs from that of the IV conversion unit 110, range switching unit 130, and charge / discharge unit 140 of the signal processing unit 100.

[0053] The IV conversion unit 1101 consists of IV conversion circuits corresponding to range 1 and range 2 connected in parallel. The IV conversion circuit for range 1 is composed of a parallel circuit of resistor R1 and capacitor C1. The input side of this parallel circuit is connected to the input terminal (not shown) of the signal processing unit 101 and the inverting terminal of the amplifier 121, and the output side is connected to switch S1A of the range switching unit 1301. The IV conversion circuit for range 2 is composed of a parallel circuit of resistor R2 and capacitor C2. The input side of this parallel circuit is connected to the input terminal (not shown) of the signal processing unit 101, and the output side is connected to switch S2A of the range switching unit 1301.

[0054] The range switching unit 1301 is configured by connecting switch units corresponding to the IV conversion circuits of each range in parallel. Each switch unit consists of two switches: the switch unit corresponding to range 1 consists of an input switch S1A and an output switch S1B. The switch unit corresponding to range 2 consists of an input switch S2A and an output switch S2B. The input switches S1A and S2A switch the on / off state of the IV conversion circuit of the corresponding range and the output switches S1B and S2B, respectively. The output switches S1B and S2B switch the connection destination of the output side of the IV conversion circuit of each range between the charge / discharge unit 1401 and the output terminal of the amplifier 121. All switches are controlled by the calculation unit 150.

[0055] The charging / discharging unit 1401 has an input side that can be connected to and disconnected from switches S1B and S2B corresponding to each range, and an output side that is connected to ground potential.

[0056] This section describes the range switching in the signal processing unit 101. Here, we will explain the case of switching from range 1 to range 2. In the initial state, switch S1A is ON and switch S2A is OFF, and switches S1B and S2B are connected to the output terminals of amplifier 121, respectively. At this time, the IV conversion circuit of range 1 constitutes the feedback circuit of amplifier 121, so the IV conversion circuit of range 1 is turned ON, and measurement is performed using range 1.

[0057] When switching ranges, switch S2A is turned on, and switch S1B is switched to the charge / discharge unit 1401 side. As a result, the IV conversion circuit of range 2 forms the feedback circuit of amplifier 121, turning on the IV conversion circuit of range 2, and switch S1B is connected to the ground potential of the charge / discharge unit 1401, forming a discharge circuit from capacitor C1 to capacitor C2, and discharge occurs from capacitor C1 to capacitor C2. In other words, the charge / discharge process is performed.

[0058] Next, switch S1A is turned off to disable the IV conversion circuit for range 1, and switch S1B is connected back to the output terminal of amplifier 121. From here on, measurements are performed in range 2.

[0059] The output switches S1B and S2A must use components with low leakage current, such as relays. As a result, the output switches of the range switching unit 1301 always have low impedance, allowing semiconductor switches such as analog switches, which have high leakage current but can operate at high speeds, to be used for the input switches S1A and S2B.

[0060] Next, a second modification of Embodiment 1 will be described. Figure 15 is a configuration diagram showing a second modification of the signal processing unit according to Embodiment 1. Note that equation (1) above also holds true in the second modification. For this reason, in the signal processing unit 102, the capacitors for each range of the IV conversion unit 1102 also become part of the charge / discharge unit 1402. Although Figure 15 shows the case with two ranges, the same applies to cases with three or more ranges. The configuration of the IV conversion unit 1102, range switching unit 1302, and charge / discharge unit 1402 of the signal processing unit 100 differs from that of the IV conversion unit 110, range switching unit 130, and charge / discharge unit 1402 of the signal processing unit 100.

[0061] The IV conversion unit 1102 consists of IV conversion circuits corresponding to range 1 and range 2 connected in parallel. The IV conversion circuit for range 1 is composed of a parallel circuit of resistor R1 and capacitor C1. A circuit 1321, consisting of two diodes connected in antiparallel, is connected to the output side of resistor R1 and the switch S1 of the range switching unit 1302. A voltage follower 1311 is also provided between resistor R1 and capacitor C1. The voltage follower 1311 has an inverting input terminal and an output terminal connected, and its output terminal is connected to the output side of capacitor C1 and the calculation unit 150. The non-inverting terminal is connected between resistor R1 and circuit 1321.

[0062] The IV conversion circuit for range 2 is composed of a parallel circuit of resistor R2 and capacitor C2. A circuit 1322, consisting of two diodes connected in antiparallel, is connected to the output side of resistor R2 between it and switch S2 of the range switching unit 1302. Furthermore, a voltage follower 1312 is provided between resistor R2 and capacitor C2. The voltage follower 1312 has an inverting input terminal and an output terminal connected, and its output terminal is connected to the output side of capacitor C2 and the calculation unit 150. The non-inverting terminal is connected between resistor R2 and circuit 1322.

[0063] The range switching unit 1302 is configured by connecting switches corresponding to the IV conversion circuits of each range in parallel. The switch unit corresponding to range 1 has its input side connected to circuit 1321, and its output side can be switched between the charge / discharge unit 1402 and the output terminal of amplifier 121. Similarly, the switch unit corresponding to range 2 has its input side connected to circuit 1322, and its output side can be switched between the charge / discharge unit 1402 and the output terminal of amplifier 121. Switches S1 and S2 are controlled by the calculation unit 150.

[0064] The charging / discharging section 1402 has an input side that can be connected to and disconnected from switches S1 and S2 corresponding to each range, and an output side that is connected to ground potential.

[0065] This section describes the range switching in the signal processing unit 102. Here, we will explain the case of switching from range 1 to range 2. In the initial state, the output side of switch S1 is connected to the output terminal of amplifier 121, and the output side of switch S2 is connected to the charge / discharge unit 1402. At this time, for range 1, the lower diode of circuit 1321 is turned on, and a feedback circuit is formed. That is, the IV conversion circuit for range 1 is on. On the other hand, the output side of switch S2 is connected to ground potential. In this case, the output voltage of voltage follower 1312 becomes the ground voltage, and the charge of capacitor C2 is discharged. As a result, the voltages across the two diodes constituting circuit 1322 become the same potential, and due to the exponential characteristics of the diodes, this is equivalent to the switch-off state. That is, the IV conversion circuit for range 2 is off. In this way, circuits 1321 and 1322, which are combinations of diodes, each function as a switch.

[0066] During range switching, the output of switch S2 is connected to the output terminal of amplifier 121, and the output of switch S1 is connected to the charge / discharge unit 1402. As a result, the output of switch S1 is connected to ground potential, and capacitor C1 is discharged. The charge discharged from capacitor C1 charges capacitor C2. Therefore, circuit 1322 is now on and circuit 1321 is off, forming a feedback circuit by the IV conversion circuit for range 2, and the range is switched to range 2.

[0067] Note that the input side of the IV conversion unit 1102 is virtually grounded, which remains unchanged from Embodiment 1. Therefore, the potential on the input side of resistors R1 and R2 is also ground potential, and the voltage across resistors R1 and R2 is equal to the output voltage of voltage followers 1311 and 1312, respectively. Therefore, the output voltage of voltage followers 1311 and 1312 is equal to the output voltage VO, and by measuring the output voltage of voltage followers 1311 and 1312, the current value of the current signal CI can be measured in each range.

[0068] Furthermore, since the output side of the diode always has low impedance, semiconductor switches such as analog switches, which have a large leakage current but can operate at high speed, can be used as switches S1 and S2, enabling faster operation than using relays.

[0069] Embodiment 2. Next, Embodiment 2 will be described based on Figures 16 to 18. Components identical or equivalent to those shown in Figures 1 to 15 are denoted by the same reference numerals, and their descriptions are omitted. Embodiment 2 has the same overall configuration as Embodiment 1, but the signal processing unit is different. Furthermore, Embodiment 2 assumes that the constants of the IV conversion circuit can be arbitrarily set, without being bound by equation (1), which was considered valid in Embodiment 1. Figure 16 is a configuration diagram showing the signal processing unit according to Embodiment 2. For simplicity of explanation, only ranges 1 and 2 are shown in Figure 16, but the same applies if there are ranges 3 and above. The signal processing unit 200 has the same IV conversion unit 110, amplification unit 120, and range switching unit 130 as the signal processing unit 100 of Embodiment 1, but the charge / discharge unit 240 and calculation unit 250 differ from those of Embodiment 1. For simplicity of explanation, Embodiment 2 uses a method where the measurement range is achieved by turning on only one IV conversion circuit.

[0070] If the constants (resistance of resistors, capacitance of capacitors) of the IV conversion circuit for each range in the IV conversion unit 110 are arbitrary values, then when the charge and discharge process during range switching fully charges the capacitor of the destination range (after switching) from the capacitor of the source range (before switching), there is a possibility of an excess or deficiency in charging and discharging. A feature of Embodiment 2 is that this excess or deficiency is compensated for by the charge pre-charged in the compensation capacitor Cc (described later). If charging and discharging is insufficient, the compensation capacitor Cc functions as a source and performs additional charging. If charging and discharging is excessive, the compensation capacitor Cc functions as a sink and absorbs the charge remaining in the capacitor of the source range. However, in the following, in all cases, this will be referred to as "charge amount," and the positive or negative sign of the charge amount will be used to distinguish whether the compensation capacitor Cc functions as a sink or a source.

[0071] The charging / discharging unit 240 is equipped with switches corresponding to the IV conversion circuits for each range, similar to the charging / discharging unit 140, and includes switches SW1 and SW2 connected in parallel. The input side of switch SW1 is connected to the output side of capacitor C1, that is, between capacitor C1 and switch SC1. The input side of switch SW2 is connected to the output side of capacitor C2, that is, between capacitor C2 and switch SC2. The output sides of switches SW1 and SW2 are connected to ground potential.

[0072] The charging / discharging unit 240 also includes a DC variable power supply 241 and a compensation capacitor Cc connected to the DC variable power supply 241 via a switch SW3. One end (left side in the figure) of both the DC variable power supply 241 and the compensation capacitor Cc is connected to the input terminal (not shown) of the signal processing unit 200. Hereafter, this will be referred to as the input side of the DC variable power supply 241 and the compensation capacitor Cc, and the opposite side will be referred to as the output side. The output side of the DC variable power supply 241 and the compensation capacitor Cc is connected to ground potential. When the switch SW3 is turned on, the DC variable power supply 241 charges the compensation capacitor Cc. The charge stored in the compensation capacitor Cc is used when there is an excess or deficiency in the charge / discharge amount during the charging / discharging process when switching ranges, so the compensation capacitor Cc is charged only by the required amount. The specific amount of charge is determined by the combination of the source range and the destination range.

[0073] The input side of the DC variable power supply 241 and the compensation capacitor Cc are connected to the input side of the IV conversion unit via switch SW4. When switch SW4 is turned on, discharge occurs from the compensation capacitor Cc to the capacitor of the switching destination range of the IV conversion unit 110, or from the capacitor of the switching source range to the compensation capacitor Cc. The DC variable power supply 241, switch SW3, and switch SW4 are controlled by the calculation unit 250.

[0074] Figure 17 is a diagram showing the charge amount table for the compensation capacitor according to Embodiment 2. The charge amount table T is a table that shows the charge amount Qij that should be charged to the compensation capacitor Cc in accordance with the case of switching from range i (i=1, 2, ...n) to range j (j=1, 2, ...n). The charge amount table T is stored in the memory of the calculation unit 250, and the calculation unit 250 determines the charge amount of the compensation capacitor Cc based on the source range and the destination range, and instructs the DC variable power supply 241 to charge the compensation capacitor Cc by the determined charge amount. The charge amount Qij can be determined in advance from the constants (Ri and Ci) of the IV conversion circuit of the source range and the constants (Rj and Cj) of the IV conversion circuit of the destination range, so the charge amount table T is created in advance.

[0075] In the second embodiment, it is sufficient to compensate for the insufficient charge amount for the capacitor of the switching target range, so the charge / discharge unit 240 is not limited to a compensating capacitor Cc, but may be configured to function as a compensating sink or source.

[0076] Next, the operation will be described. Embodiment 2 has the same overall operation as Embodiment 1, but the range switching process flow is different. Figure 18 is a flowchart showing the range switching process according to Embodiment 2. First, the IV conversion circuit of the target range is turned on (step ST711).

[0077] Next, the IV conversion circuit for the source range is turned off (step ST712). This ensures that only the IV conversion circuit for the destination range is turned on.

[0078] Next, the capacitor of the source range is discharged to the capacitor of the destination range (step ST713, charge / discharge process). This charge / discharge process is the same as in Embodiment 1. As a result, the capacitor of the destination range is charged.

[0079] Next, the system is charged to compensate for any deficiency or discharged to compensate for any excess (step ST714). Since the compensation capacitor Cc has the required amount of charge, switch SW3 of the charge / discharge unit 240 is turned off, and switch SW4 is turned on to additionally charge the capacitor of the selected range.

[0080] Next, the charging and discharging process is completed by making the output side of the IV conversion circuit of the switching source range high impedance (step ST715). This high impedance process is the same as in Embodiment 1.

[0081] According to Embodiment 2, the same effects as in Embodiment 1 can be obtained. Furthermore, even if the product of the resistance value of the resistor and the capacitance of the capacitor in the IV conversion circuit of each range is not equal, it is possible to prevent overcharging or undercharging during the charging and discharging process. More specifically, the charging and discharging unit comprises a variable DC power supply and a compensation capacitor charged by this variable DC power supply, and after the charging and discharging process of Embodiment 1, the compensation capacitor is configured to charge the capacitor corresponding to the switching destination range. As a result, if the charge of the capacitor in the switching destination range is insufficient, additional charging is performed. Therefore, even if the product of the resistance and capacitance in the IV conversion circuit of each range is not equal, the capacitor in the switching destination range is charged without overcharging or undercharging. For this reason, the resistance value of the resistor and the capacitance of the capacitor in the IV conversion circuit of each range can be set arbitrarily.

[0082] Embodiment 3. Next, Embodiment 3 will be described based on Figures 19 to 21. Components identical or equivalent to those shown in Figures 1 to 18 are denoted by the same reference numerals, and their descriptions are omitted. Embodiment 3 updates the charge amount table of Embodiment 2 using reinforcement learning. As described above, the charge amount required for the compensation capacitor Cc can be determined in advance from the constants of the IV conversion circuit of the source range and the IV conversion circuit of the destination range. However, due to individual differences in components and environmental characteristics, there is a risk of discrepancies between the actual required charge amount and the design value. Embodiment 3 optimizes the charge amount of the compensation capacitor Cc using reinforcement learning to compensate for such discrepancies. For simplicity of explanation, Embodiment 3 uses a method that realizes the measurement range by turning on only one IV conversion circuit.

[0083] Let's explain using the example of switching from range 1 to range 2. The amount of charge required for the compensation capacitor Cc is determined by the circuit constants R1 and C1 of the source range and the circuit constants R2 and C2 of the destination range, but there may be a discrepancy between the true values ​​and the design values ​​of these circuit constants. Let R1, C1, R2, and C2 be the true values, and R1*, C1*, R2*, and C2* be the design values. Also, let the deviations for each circuit constant be ΔR1, ΔC1, ΔR2, and ΔC2 (e.g., R1* + ΔR1 = R1). When switching from range 1 to range 2, if equation (2) below holds true, the amount of charge in capacitor C2 is insufficient, and the measured value X immediately after the range switch will be less than the true value of the current being measured. Conversely, if equation (3) holds true, the amount of charge in capacitor C2 is excessive, and the measured value X immediately after the range switch will be more than the true value of the current being measured. ((R2*+ΔR2)×(C2*+ΔC2)) / ((R1*+ΔR1)×(C1*+ΔC1))>(R2*×C2*) / (R1*×C1*) ···(2) ((R2*+ΔR2)×(C2*+ΔC2)) / ((R1*+ΔR1)×(C1*+ΔC1))<(R2*×C2*) / (R1*×C1*) ···(3)

[0084] If equation (2) is true, the charge of the compensating capacitor Cc is increased, and if equation (3) is true, the charge of the compensating capacitor Cc is decreased. Equations (2) and (3) compare the ratio of the time constants of the IV conversion circuit of the source range and the IV conversion circuit of the destination range based on true values, with the ratio of the time constants of the IV conversion circuit of the source range and the IV conversion circuit of the destination range based on design values.

[0085] The update of the charge amount using reinforcement learning is performed by inference using a trained model. Therefore, Embodiment 3 also involves training using a trained model. Figure 19 is a configuration diagram showing the learning unit according to Embodiment 3. The learning unit 710 comprises a data acquisition unit 711 and a model generation unit 712. The learning unit 710 may be configured as an arithmetic unit 250, or as a separate learning device.

[0086] The data acquisition unit 711, i.e., the first data acquisition unit, acquires data on the state ST and charge amount Q* of the nuclear instrumentation system from an external source. Specific examples of state ST include the design values ​​of the circuit constants (resistance, capacitance) of the IV conversion circuits for the source and destination ranges, and the output voltage VO before and after range switching, as well as its time progression. The state of the nuclear instrumentation system may also include the temperature, humidity, and operating time of the signal processing unit. Including these allows for the reflection of temperature characteristics, humidity characteristics, and the effects of changes over time, respectively. The charge amount Q* is the charge amount corresponding to the combination of the source and destination ranges (corresponding to Qij in the charge amount table T), and can be obtained from the charge amount table T. The data acquisition unit 711 sends the acquired data to the model generation unit 712 as training data.

[0087] The model generation unit 712 learns and updates the learned model M based on two inputs (state ST and charge amount Q*), and stores the updated learned model M as the output learned model M* in the learned model storage unit 720. The learned model storage unit 720 may be configured as the arithmetic unit 250 or as a separately provided storage device.

[0088] In reinforcement learning, an agent (an actor) in a given environment observes the current state (environmental parameters) and decides what action to take. The environment changes dynamically as a result of the agent's actions, and the agent is rewarded according to the changes in the environment. The agent repeats this process and learns the action strategy that yields the most rewards through a series of actions. Representative reinforcement learning methods include Q-learning and TD-learning. For example, in the case of Q-learning, the general update formula for the action-value function Q(s,a) is expressed by equation (4) below.

number

[0089] The update formula, represented by equation (4), increases the action value Q of the action a with the highest Q value at time t+1 if that value is greater than the action value Q of the action a performed at time t, and decreases the action value Q if the opposite is true. In other words, it updates the action value function Q(s,a) so that the action value Q of action a at time t approaches the best action value at time t+1. As a result, the best action value in a given environment is sequentially propagated to the action values ​​in previous environments.

[0090] As described above, when a trained model M* is generated by reinforcement learning, the model generation unit 712 includes a reward calculation unit 712a and a function update unit 712b.

[0091] The reward calculation unit 712a calculates the reward based on the charge amount Q* and the state ST. The reward calculation unit 712a calculates the reward according to a predetermined reward criterion. In Embodiment 3, the reward is determined according to the fluctuation of the current value before and after range switching. For example, the standard deviation can be used as an indicator of fluctuation. The smaller the standard deviation of the current value before and after range switching, the higher the reward. As the simplest example, a positive reward is given when the standard deviation is below a predetermined threshold, and a negative reward is given when the standard deviation is greater than the threshold.

[0092] The function update unit 712b updates the function for determining the optimal charge amount of the compensation capacitor Cc for given combinations of source and destination ranges, etc., according to the reward calculated by the reward calculation unit 712a, and outputs it to the learned model storage unit 720. For example, in the case of Q-learning, the action-value function Q(st,at) expressed by equation (4) is used as the function for calculating the optimal charge amount.

[0093] The trained model memory unit 720 stores the action-value function Q(st,at), i.e., the trained model M*, which has been updated by the function update unit 712b.

[0094] Figure 20 is a diagram showing the inference unit according to Embodiment 3. The inference unit 730 comprises a data acquisition unit 731 and a charge amount inference unit 732.

[0095] The data acquisition unit 731, i.e., the second data acquisition unit, acquires data of state ST as described above. The data acquisition unit 731 sends the acquired data to the charge amount inference unit 732.

[0096] The charge amount inference unit 732 infers the optimal charge amount Q** using the trained model M*. That is, by inputting the state ST data acquired by the data acquisition unit 731 into the trained model M*, the optimal charge amount Q** for the input state ST can be inferred. The charge amount inference unit 732 outputs the inferred charge amount Q** and updates the data in the charge amount table T (data on the charge amount for the corresponding combination of source range and destination range).

[0097] Next, the operation will be described. Figure 21 is a flowchart showing the operation of the signal processing unit of the nuclear instrumentation system in Embodiment 3. In Embodiment 3, current value measurement and reinforcement learning are performed in parallel, similar to Embodiments 1 and 2, so the processing related to reinforcement learning is shown with a double line. First, the current signal CI from the neutron detector 902a is input (step ST501).

[0098] Next, similar to Embodiment 1, the current signal CI is converted to a voltage signal (step ST502). The output voltage VO is converted from analog to digital (step ST503).

[0099] Next, similar to Embodiment 1, the optimal range is determined (step ST504), and it is determined whether or not a range switch is necessary (step ST505). If a range switch is not necessary, it is determined that the optimal range is set. From here on, the measurement of the current value and the reinforcement learning process are performed in parallel. For the measurement of the current value, the process proceeds to step ST507. For the reinforcement learning process, the process also proceeds to step ST508.

[0100] If a range change is necessary, the range change process is performed (step ST506), and after the range change, the process returns to step ST502. The details of the range change process are the same as in Embodiment 2.

[0101] If it is determined that the optimal range has been set, the current value is calculated from the output voltage VO (step ST507), similar to Embodiment 1, and the current signal generated as a result of the current value calculation is filtered to output the obtained measured value X (step ST509).

[0102] The reinforcement learning process begins with acquiring input data (step ST508). Here, "input data" refers to the state ST and charge amount Q* input to the data acquisition unit 711.

[0103] Next, judgment data is obtained based on the calculation result of step ST507 (step ST510). Here, "judgment data" refers to the data used for calculating the reward in reinforcement learning. As described above, in Embodiment 3, the reward is determined according to the fluctuation of the current value before and after range switching, and the standard deviation is used as an indicator of the fluctuation, so the standard deviation of the current value before and after range switching can be obtained from the calculation result of step ST507.

[0104] Next, the reward in reinforcement learning is calculated using the input data obtained in step ST508 and the judgment data obtained in step ST510. The learning model M is also updated (step ST511). This results in the trained model M*.

[0105] Next, the optimal charge amount Q** is inferred using the state ST from the input data acquired in step ST508 and the trained model M* acquired in step ST511, and the charge amount table T is updated based on the inference result (step ST512). The updated charge amount table T is used for subsequent measurements.

[0106] According to Embodiment 3, the same effects as in Embodiment 2 can be obtained. Furthermore, by using reinforcement learning techniques to account for the discrepancy (deviation) between the design values ​​and the actual values ​​of the circuit constants, it is possible to reflect a more optimal charge amount for the compensation capacitor in the charge amount table.

[0107] Although this application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but can be applied individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the art disclosed herein. These include, for example, modifying, adding or omitting at least one component, or even extracting at least one component and combining it with components of other embodiments. [Explanation of Symbols]

[0108] 100, 101, 102, 200 Signal processing unit, 110, 1101, 1102 IV conversion unit, 120 Amplification unit, 121 Amplifier, 130, 1301, 1302 Range switching unit, 140, 1401, 1402, 240 Charge / discharge unit, 150, 250 Calculation unit, 241 DC variable power supply, 710 Learning unit, 711 Data acquisition unit, 712 Model generation unit, 720 Learned model storage unit, 730 Inference unit, 731 Data acquisition unit, 732 Charge amount inference unit, 902a, 903a, 904a Neutron detector, 910 Nuclear instrumentation device, A1, An IV conversion circuit, C1, C2, Cn Capacitor, Cc Compensation capacitor, CI Current signal, M Learned model, M* Learned model, R1, R2, Rn Resistors, S1, S1A, S1B, S2, S2A, S2B, SC1, SC2, SCn, SR1, SR2, SRn, SW1, SW2, SW3, SW4 Switches, Q*, Q** Charge level, ST State, T Charge level table, VO Output voltage, X Measured value

Claims

1. A nuclear instrumentation device having multiple ranges, including a first range and a second range, A current-voltage conversion unit is provided with a capacitor and a resistor connected in parallel, and has a current-voltage conversion circuit corresponding to the respective ranges, which converts the current input from the neutron detector into a voltage. An amplification unit that amplifies the aforementioned voltage and outputs it as an output voltage, A range switching unit having a switch for turning on and off a current-voltage conversion circuit corresponding to the second range, and changing the current-voltage conversion circuit that is turned on, or the combination of current-voltage conversion circuits that are turned on, A calculation unit determines the range used for measuring the current based on the output voltage, instructs the range switching unit to switch the range to the measurement range, calculates the current value from the output voltage, and outputs the obtained result. A nuclear instrumentation device characterized by comprising a charge / discharge unit that, when the range is switched, discharges the charge stored in a capacitor corresponding to the range before the switch, and uses the said charge to charge a capacitor corresponding to the range after the switch.

2. The nuclear instrumentation device according to claim 1, wherein the product of the resistance value of the resistor and the capacitance of the capacitor is equal for the range before switching and the range after switching, respectively.

3. The charging and discharging unit comprises a variable DC power supply and a compensating capacitor charged by the variable DC power supply. The nuclear instrumentation device according to claim 1 or 2, wherein after the charge-discharge process, the compensating capacitor is discharged to further charge the capacitor corresponding to the switched range.

4. The nuclear instrumentation device according to claim 3, wherein the calculation unit stores the amount of charge of the compensation capacitor in correspondence with the combination of the range before switching and the range after switching.

5. A learning unit having a first data acquisition unit that acquires learning data including data on the state of the nuclear instrumentation device, which includes information on the range before the switch and information on the range after the switch, and the charge amount of the compensation capacitor in the state, and a model generation unit that uses the learning data to generate a trained model that infers the charge amount of the compensation capacitor from the state data, The inference unit further comprises a second data acquisition unit for acquiring data on the aforementioned state, and a charge amount inference unit for inferring the charge amount of the compensation capacitor based on the data acquired by the second data acquisition unit using the trained model. The nuclear instrumentation device according to claim 4, wherein the charge amount of the compensation capacitor is updated based on the result of the inference by the charge amount inference unit.

6. The nuclear instrumentation device according to claim 1 or 2, wherein the charging / discharging unit has a second switch corresponding to the second range, and the input side of the second switch is connected to the output side of a capacitor corresponding to the second range, and the output side is connected to ground potential.

7. The charging and discharging unit has its input side connected to the switch and its output side connected to ground potential. The nuclear instrumentation device according to claim 1 or 2, wherein the switch switches the connection destination of the output side of the corresponding current-voltage conversion circuit between the output side of the amplification unit and the input side of the charge / discharge unit, and when the output side of the corresponding current-voltage conversion circuit is connected to the output side of the amplification unit, the current-voltage conversion circuit is turned on, and when the output side of the corresponding current-voltage conversion circuit is connected to the input side of the charge / discharge unit, the current-voltage conversion circuit is turned off.

8. The current-voltage conversion circuit is provided with a voltage follower between the capacitor and the resistor, the voltage follower having an output terminal connected to the calculation unit and outputting the output voltage to the calculation unit, the output side of the resistor is connected to the non-inverting input terminal of the voltage follower and is also connected to the input side of a circuit formed by connecting two diodes in antiparallel, and the output side of the circuit is connected to the switch, as described in claim 7.

9. The nuclear instrumentation device according to claim 1 or 2, wherein the range switching unit further comprises a switch for turning on and off a current-voltage conversion circuit corresponding to the first range.

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