WO2022215192A1 - 中性子束計測装置 - Google Patents
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- G21C17/10—Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain
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Definitions
- This application relates to a neutron flux measurement device.
- neutron flux measurement equipment that uses the output of a self-powered neutron detector that detects neutrons has been used to continuously measure the neutron flux or its distribution in nuclear reactors.
- self-powered neutron detectors use materials called emitter materials, which are relatively prone to react with neutrons, such as rhodium and vanadium. Since these substances have a high neutron capture cross-section, which means the probability of reaction with neutrons, activation reactions due to interaction with neutrons occur predominantly, and when transitioning to stable elements from nuclear transmutation by neutron capture Beta decays.
- a substance with a low neutron capture cross section called a collector material is arranged outside the emitter material via an insulator. As a result, the collector material is less likely to interact with neutrons than the emitter material, and the two are electrically insulated.
- a self-powered neutron detector that uses rhodium, vanadium, etc. as an emitter material outputs a current originating from electrons emitted by beta decay accompanying activation of the emitter material by neutron irradiation. Therefore, the neutron flux is measured indirectly by measuring the output current proportional to this neutron flux.
- interaction with neutrons causes exhaustion of the emitter material, so the sensitivity of the detector to neutrons decreases according to the amount of neutron irradiation. Therefore, for the same neutron flux, the output current from the self-powered detector decreases according to the degree of consumption of the emitter material. Therefore, it was necessary to periodically correct the detector sensitivity during periods when the self-powered detectors could not be replaced, at least during the operating cycle of the reactor.
- the neutron flux in the reactor is related to the reactor output, so the neutron irradiation dose of the detector fixed in the reactor depends on the operating mode of the reactor during the operation cycle period.
- the neutron flux measuring device for correcting a decrease in detector sensitivity when the reactor output does not fluctuate frequently, the following in-reactor neutron flux measuring device has been disclosed.
- the neutron flux measurement device in the reactor core as a conventional neutron flux measurement device is a neutron flux measurement device in the reactor core that uses a self-powered neutron detector that is fixedly installed in the core.
- Sn Sn ⁇ 1 ⁇ exp( ⁇ ) ⁇ n ⁇ 1 ⁇ t
- Sn: neutron sensitivity of self-powered neutron detector at time tn-1 tn- ⁇ tll
- Sn-1: neutron sensitivity of self-powered neutron detector at time t-1 tn- ⁇ t ⁇ : self-powered neutron detector
- the present application discloses a technique for solving the above problems, and provides a neutron flux measurement device that can accurately measure neutron flux even when the output of a nuclear reactor fluctuates. intended to
- the neutron flux measurement device disclosed in the present application is a self-powered detector that detects neutrons in a nuclear reactor; a neutron flux counter that measures the neutron flux in the reactor based on the output of the self-powered detector; a storage unit for recording, as recording data, measured values indicating changes in neutron flux in the reactor according to the adjustment control of the output of the reactor in a first set period; Detection of neutrons by the self-powered detector at time t1, which is the time point after the second set period, according to the adjustment control in the second set period after the first set period, based on the recorded data.
- a calculation unit that corrects the detector sensitivity and derives the neutron flux at the time point t1 using the corrected detector sensitivity, It is.
- the neutron flux measurement device disclosed in the present application it is possible to obtain a neutron flux measurement device that can accurately measure neutron flux even when the output of the nuclear reactor fluctuates.
- FIG. 1 is a block diagram showing a schematic configuration of a neutron flux measuring device according to Embodiment 1;
- FIG. 1 is a diagram showing a schematic configuration of a self-powered neutron detector according to Embodiment 1;
- FIG. Fig. 10 shows the change in corrected detector sensitivity;
- FIG. 3 is a block diagram showing a schematic configuration of a neutron flux measuring device according to Embodiment 2;
- FIG. 4 is a diagram showing changes in reaction cross sections for neutron capture of rhodium and vanadium; It is a schematic diagram which shows the temperature dependence of a reaction cross section.
- FIG. 10 is a configuration diagram of a learning device included in a calculation unit related to the neutron flux measuring device according to Embodiment 3;
- FIG. 10 is a diagram showing the configuration of a neural network according to Embodiment 3; 10 is a flowchart relating to learning processing of the learning device according to Embodiment 3; FIG. 10 is a diagram showing the configuration of an inference device relating to the neutron flux measurement device according to Embodiment 3; 10 is a flowchart of learning processing of the inference device according to Embodiment 3; FIG. 11 is a diagram showing an example of a hardware configuration of a computing unit according to Embodiment 3;
- FIG. 1 is a block diagram showing a schematic configuration of a neutron flux measurement device 100 according to Embodiment 1.
- the neutron flux measurement device 100 includes a self-powered neutron detector 1 as a self-powered detector, a neutron flux counter 2 , a calculator 10 and a host device 3 . The details of these components that constitute the neutron flux measurement device 100 will be described below.
- FIG. 2 is a diagram showing a schematic configuration of the self-powered neutron detector 1 shown in FIG.
- a self-powered neutron detector 1 is arranged in the core of a nuclear reactor to detect neutrons in the core.
- the self-powered neutron detector 1 includes, for example, an emitter material 1a as a metal of a sensitive part, a collector material 1b as a covering material, and between the emitter material 1a and the collector material 1b An insulator 1c is provided, and signal lines 1d and 1e are connected to the emitter material 1a and the collector material 1b, respectively.
- the self-powered neutron detector 1 a current is generated by a nuclear reaction or activation reaction caused by the incidence of neutrons on the emitter material 1a, and the generated current is output to the outside. Therefore, the self-powered neutron detector 1 does not require the supply of an external power source for driving the neutrons into a detectable state, and the current having a magnitude uniquely determined according to the neutron flux at the position in the reactor is arranged. to output The output current is input to the neutron flux counting section 2 via signal lines 1d and 1e.
- cobalt is generally used in addition to rhodium or vanadium from the conditions such as the size of the activation cross-section for neutrons and the decay time constant after activation. .
- the neutron flux counting unit 2 receives the current output from the self-powered neutron detector 1, converts it into neutron flux based on the magnitude of the input current, and has a function of counting the converted neutron flux. .
- the neutron flux counting unit 2 performs calculation according to the following equation (1) in order to convert the input current into neutron flux.
- ⁇ represents the number of neutrons passing through a unit area in a unit time, or the neutron flux indicating the total distance traveled by neutrons in a unit volume in a unit time.
- I represents the current value output by the self-powered neutron detector 1 .
- S represents the detector sensitivity of the self-powered neutron detector 1, which is the current from the self-powered neutron detector 1 divided by the neutron flux density.
- the detector sensitivity of the self-powered neutron detector 1 does not change, that is, when the emitter material 1a is not consumed, the detector sensitivity of the self-powered neutron detector 1 at the measurement start time (time t0) is , the detector sensitivity S0 at the measurement start time (time t0) when the self-powered neutron detector 1 starts measuring neutrons.
- the neutron flux transmitted from the neutron flux counting section 2 to the neutron flux correction calculating section 11 is expressed by the following equation (2).
- ⁇ ′ represents the value of the neutron flux measured by the neutron flux counter 2 at the measurement start time (time t0).
- the detector sensitivity changes as the emitter material 1a of the self-powered neutron detector 1 is activated and consumed. Therefore, it is necessary to correct the detector sensitivity in order to correctly measure the neutron flux at (time t1) when the measurement period T2 as the second set period has elapsed from the measurement start time (time t0). be.
- time t1 when the measurement period T2 has elapsed from time t0 is described as the current time. The principle of correcting the detector sensitivity of the self-powered neutron detector 1 will be described below.
- the amount of activation of the emitter material 1a of the self-powered neutron detector 1 by neutrons in the nuclear reactor is expressed by the following formula (3).
- N represents the number of activated atoms in the emitter material 1a of the self-powered neutron detector 1;
- ⁇ represents a reaction cross-sectional area indicating the probability that a particle incident on the emitter material 1a of the self-powered neutron detector 1 reacts with the nucleus in the emitter material 1a.
- ⁇ represents the neutron flux entering the emitter material 1 a of the self-powered neutron detector 1 .
- reaction cross section is quoted from evaluated nuclear data libraries published by each country, for example, JENDL (Japanese Evaluated Nuclear Data Library) in the case of Japan, ENDF (Evaluated Nuclear Data File) in the case of the United States, etc. .
- the neutron flux entering the emitter material 1a of the self-powered neutron detector 1 changes according to the output of the nuclear reactor, so it becomes a function of time as shown in the above equation (3).
- Solving the above equation (3) for the number N of atoms to be activated in the sensitive part of the detector of the self-powered neutron detector 1 yields the following equation (4).
- N0 represents the number of atoms at the measurement start time (time t0) when the self-powered neutron detector 1 started neutron flux measurement.
- the number of atoms N that decreases due to activation of the emitter material 1a of the self-powered neutron detector 1 in the nuclear reactor is after the measurement period T2 has elapsed from the measurement start time (time t0) of the neutron flux. is affected by the result of integration of the neutron flux up to the current time (time t1).
- the detector sensitivity of the self-powered neutron detector 1 in the nuclear reactor is proportional to the number of atoms in the emitter material 1a, it can be expressed as Equation (5) below.
- S represents the detector sensitivity of the self-powered neutron detector 1 at the current time (time t1).
- K represents a proportional coefficient between the detector sensitivity of the self-powered neutron detector 1 and the number of atoms of the emitter material 1a of the self-powered neutron detector 1;
- the sensitivity of the detector decreases over time as the neutron flux measurement continues. Therefore, when the detector sensitivity is not corrected, even if the neutron flux in the nuclear reactor does not change, the neutron flux is measured as if it is apparently decreasing.
- the calculation for correcting the detector sensitivity of the self-powered neutron detector 1 can be represented by the following equation (6).
- S0 represents the detector sensitivity of the self-powered neutron detector 1 at the neutron flux measurement start time (time t0).
- the detector sensitivity S of the self-powered neutron detector 1 at the current time (time t1) is the self-powered neutron detector 1 at the neutron flux measurement start time (time t0) can be derived by correcting the detector sensitivity S0 of , by the amount indicated by the exp function.
- the correction amount can be accurately calculated by continuously measuring the neutron flux and integrating it as shown in the above equation (6) over the measurement period T2.
- the calculation of the correction amount is performed using a difference formula as shown in the following formula (7).
- ⁇ t represents the measurement interval in the measurement period T2.
- the measurement interval ⁇ t is set shorter than the time during which the reactor output or the neutron flux in the reactor changes.
- FIG. 3 is a diagram showing changes in detector sensitivity corrected based on the above equation (7).
- the detector sensitivity Ss corrected when the measurement interval ⁇ t for measuring the neutron flux is shorter than the time when the reactor output or the neutron flux in the reactor changes, and when it is longer and the detector sensitivity Sl with which the
- the computing unit 10 of the present embodiment shortens the neutron flux measurement interval ⁇ t during the neutron flux measurement period T2 to be shorter than the time during which the neutron flux in the reactor changes. Increase the accuracy of neutron flux measurement.
- the calculation unit 10 of the neutron flux measurement device 100 of the present embodiment calculates the neutron flux counted at the current time (time t1) according to the degree of depletion of the detector sensitivity of the self-powered neutron detector 1. Control for correction will be described.
- the calculation unit 10 includes a neutron flux correction calculation unit 11 , a neutron flux storage unit 12 and a detector sensitivity correction calculation unit 13 .
- the neutron flux storage unit 12 has a function of storing and holding the value of the detected neutron flux.
- a memory, a hard disk, an external storage medium, etc. are used. Selected and configured.
- the neutron flux storage unit 12 pre-stores, as record data D, a plurality of neutron flux count values counted during the first set period T1 past the measurement start time t0.
- a plurality of neutron fluxes in the record data D are recorded corresponding to the adjustment control of the reactor power performed during the first set period T1. Therefore, a plurality of neutron fluxes in this record data D show changes in count values of the neutron flux in the reactor according to the adjustment control of the output of the reactor.
- the detector sensitivity correction calculation unit 13 corrects the detector sensitivity of the self-powered neutron detector 1 at the current time (time t1) based on the recorded data D recorded in the neutron flux storage unit 12 .
- the record data D recorded in the neutron flux storage unit 12 is the count value of the neutron flux in the reactor according to the adjustment control of the output of the reactor, which was counted in the past first set period T1. It shows the change of
- the detector sensitivity correction calculation unit 13 of the present embodiment is based on the recorded record data D, and adjusts the reactor at the measurement start time (time point t0) of the measurement period T2 after the first set period T1. Based on the control, the time interval ⁇ tc at which the neutron flux in the reactor changes during the measurement period T2 is estimated. Then, the detector sensitivity correction calculation section 13 sets the measurement interval ⁇ t in the measurement period T2 so as to be shorter than the estimated time interval ⁇ tc at which the neutron flux in the reactor changes.
- the neutron flux is measured by the neutron flux counting section 2 at the set measurement interval ⁇ t. These measured neutron fluxes are recorded in the recording data D in the neutron flux storage unit 12 . Then, the detector sensitivity correction calculation unit 13 uses the measured values of the neutron flux recorded in the recording data D, based on the above equation (7), the self-powered neutron at the current time (time t1) Detector sensitivity of detector 1 is corrected.
- the detector sensitivity correction calculation unit 13 uses a plurality of neutron fluxes measured at each measurement interval ⁇ t shorter than the time interval ⁇ tc of the neutron flux that changes according to the output adjustment control of the nuclear reactor, The detector sensitivity at the current time (time t1) is derived with high accuracy.
- the derived detector sensitivity at the current time (time t ⁇ b>1 ) is input to the neutron flux correction calculator 11 .
- the neutron flux correction calculation unit 11 corrects the neutron flux input from the neutron flux counting unit 2 by the change in the corrected detector sensitivity input from the detector sensitivity correction calculation unit 13, and corrects the neutron flux. to calculate
- the neutron flux correction calculation unit 11 uses the corrected detector sensitivity at the current time (time point t1), which is transmitted from the detector sensitivity correction calculation unit 13, and hereinafter, according to the equation (8), from the neutron flux counting unit 2 Correct the entered neutron flux value.
- ⁇ represents the corrected neutron flux value measured by the neutron flux counter 2 .
- ⁇ ′ represents the value of the neutron flux before correction measured by the neutron flux counter 2 .
- the neutron flux correction calculator 11 transmits the corrected neutron flux at the current time (time t ⁇ b>1 ) to the neutron flux storage 12 .
- the neutron flux storage unit 12 records the corrected neutron flux at the current time (time t1) in the record data D, and uses it in the correction of the neutron flux after the current time (t1).
- the neutron flux correction calculator 11 outputs the obtained neutron flux after correction to the host device 3 .
- the host device 3 is a device that processes the neutron flux transmitted from the neutron flux correction calculation unit 11, and is, for example, a computer for reactor control, a display screen for reactor status monitoring, and the like.
- the neutron flux measurement device of the present embodiment can detect the current time independent of the degree of deterioration even when the degree of deterioration of the self-powered neutron detector changes according to the adjustment of the output control of the nuclear reactor. It is possible to accurately derive the actual neutron flux in the reactor at
- the neutron measuring device of this embodiment configured as described above is a self-powered detector that detects neutrons in a nuclear reactor; a neutron flux counter that measures the neutron flux in the reactor based on the output of the self-powered detector; a storage unit for recording, as recording data, measured values indicating changes in neutron flux in the reactor according to the adjustment control of the output of the reactor in a first set period; Detection of neutrons by the self-powered detector at time t1, which is the time point after the second set period, according to the adjustment control in the second set period after the first set period, based on the recorded data.
- a calculation unit that corrects the detector sensitivity and derives the neutron flux at the time point t1 using the corrected detector sensitivity, It is.
- the neutron flux measuring device includes a storage unit that records measured values indicating changes in the neutron flux in the nuclear reactor according to the adjustment control of the output of the nuclear reactor in the past first set period as recorded data. . Then, based on the recorded data in the past first set period, the neutron flux measurement device, according to the adjustment control of the nuclear reactor in the second set period that is the measurement period, the current time that is the elapsed point of the measurement period Correction of the neutron detector sensitivity at time t1 is performed. In this way, even when the output of the nuclear reactor frequently fluctuates during the second set period, which is the measurement period, the detector sensitivity can be corrected in accordance with the fluctuations in the neutron dose due to the adjustment control of the nuclear reactor. Therefore, an accurate neutron flux can be obtained that does not depend on variations in the degree of deterioration of the self-powered detector caused by variations in the neutron irradiation dose.
- the detector sensitivity of the self-powered neutron detector 1 can be accurately corrected according to the output fluctuation of the nuclear reactor, it is not necessary to separately provide a calibration detector in the reactor. Therefore, no correction error occurs due to a mismatch between the neutron dose at the installation position of the self-powered neutron detector to be corrected and the dose of the calibration detector.
- the number of devices does not increase, maintenance work for the devices can be eliminated, and costs can be reduced.
- the calculation unit is estimating a time interval ⁇ tc at which the neutron flux count in the reactor changes according to the adjustment control of the reactor in the second set period, based on the recorded data; Based on the time interval ⁇ tc, the measurement interval ⁇ t by the neutron flux counting unit in the second set period is adjusted to correct the detector sensitivity of the self-powered detector at the time t1, It is.
- the neutron measuring device adjusts the reactor output in the second set period, which is the measurement period, based on the recorded data showing the change in the neutron flux according to the past adjustment control of the reactor output. It is possible to estimate the time interval ⁇ tc in which the neutron flux changes according to the control. Then, by adjusting the measurement interval ⁇ t in the measurement period based on the time interval ⁇ tc at which the neutron flux changes, which is estimated with high accuracy, the detector according to the fluctuation of the neutron irradiation dose due to the adjustment control of the reactor output Correction with good sensitivity accuracy can be performed.
- the measurement interval ⁇ t is set shorter than the estimated time interval ⁇ tc, It is.
- the detector sensitivity can be corrected with high accuracy.
- the calculation unit is The detector sensitivity of the self-powered detector at time t1 is derived based on the following equation using the detector sensitivity of the self-powered detector at time t0, which is the measurement start time of the second set period.
- the calculation unit is In correcting the detector sensitivity of the self-powered detector at the time t1, Using the neutron flux at all the measurement points measured within the second set period, It is.
- the neutron measurement device When the neutron flux measurement interval ⁇ t is finite, the neutron measurement device The detector sensitivity of the self-powered detector at time t1, which is the current time, is corrected using the neutron flux at the measurement time points at every measurement interval ⁇ t, which is measured within the second set period, which is the measurement period. . In this way, all the neutron fluxes measured at each measurement interval ⁇ t are used, and calculations for large approximations are not performed, so that the accumulation of correction errors can be suppressed, and accurate detector sensitivity correction can be performed. can do
- FIG. 4 is a block diagram showing a schematic configuration of a neutron flux measurement device 200 according to Embodiment 2. As shown in FIG.
- the detector sensitivity correction calculation unit 13 corrects the detector sensitivity independent of fluctuations in the degree of deterioration of the self-powered detector according to the adjustment control of the output of the nuclear reactor. As shown in FIG. 4, the in-reactor temperature Ta in the reactor is input to the detector sensitivity correction calculation section 13 of the present embodiment. Then, the detector sensitivity correction calculation section 13 corrects the detector sensitivity reflecting the temperature dependence of the reaction area of the self-powered detector based on the input reactor temperature Ta.
- the in-core temperature Ta may be measured, for example, by a plurality of thermometers that measure the temperature around the emitter material 1a of each self-powered neutron detector 1 installed in the reactor.
- the in-core temperature Ta may be measured by at least one thermometer that measures a typical in-core temperature Ta in the reactor. Note that the in-core temperature Ta is directly input from the thermometer to the sensitivity correction calculation unit, for example, the in-core temperature Ta is temporarily integrated in the host device 3, or the in-core temperature Ta calculated by a core simulator or the like is But it's okay.
- FIG. 5 is a diagram showing a change in reaction cross-sectional area for neutron capture of rhodium and vanadium of the emitter material 1a used in a general self-powered neutron detector 1.
- FIG. 6 is a schematic diagram showing the temperature dependence of the reaction cross section.
- FIG. 6 shows the reaction cross section ⁇ 21 at low temperature and the reaction cross section ⁇ 22 at high temperature.
- the reaction cross-section shows a correlation with temperature due to an effect called the Doppler effect, in which the thermal motion of the atomic nucleus of a substance becomes active and neutrons are easily absorbed when the reactor temperature Ta rises.
- the Doppler effect in which the thermal motion of the atomic nucleus of a substance becomes active and neutrons are easily absorbed when the reactor temperature Ta rises.
- control rods are moved in and out to adjust the nuclear reaction in the core.
- concentration of boric acid diluted in the coolant is adjusted, and in the case of a boiling water reactor, etc., by adjusting the flow rate in the reactor, The reactor power is adjusted by varying the in-reactor temperature Ta resulting from the reaction.
- the core temperature Ta also locally fluctuates as the local nuclear reactions are adjusted. Therefore, in the detector sensitivity correction performed by the detector sensitivity correction calculation unit 13, the accuracy of correcting the consumption of the emitter material 1a can be improved by reflecting the furnace temperature Ta on the reaction cross-sectional area. As a result, it is possible to prevent an operation that is too small or too large from the actual value.
- the temperature distribution of the core temperature is also caused by adjusting the boric acid concentration and flow rate, although not as much as the insertion and withdrawal of the control rods. By making them correspond to each other, it is possible to ensure the accuracy of correcting the consumption of the emitter material 1a.
- the reaction cross-sectional area due to the Doppler effect is added to the above equation (7) for calculating the detector sensitivity of the detector sensitivity correction calculation unit 13. , as a function ⁇ (t) with respect to the furnace temperature Ta, as shown in Equation (9).
- the reactor temperature Ta the temperature corresponding to the temperature at the time when the neutron flux used in the detector sensitivity correction calculation unit 13 is measured is applied.
- the reaction cross-sectional area with respect to the in-furnace temperature Ta may be given from the result of functioning the reaction cross-sectional area with respect to the in-furnace temperature Ta, or the corresponding A value that matches or is close to the in-furnace temperature Ta may be given.
- reaction cross sections are quoted from the evaluated nuclear data libraries published by each country.
- Reaction cross-sectional area data for the in-furnace temperature Ta may be created using actual measurement, simulation, or the like, in addition to functioning with respect to the in-furnace temperature Ta, discretization by interpolation or extrapolation.
- the neutron measuring device of this embodiment configured as described above is A temperature detector that detects the temperature inside the reactor, The computing unit corrects the value of the neutron reaction cross section of the self-powered detector according to the temperature detected by the temperature detector, It is.
- the temperature dependence of the activated reaction cross-section of the self-powered neutron detector can be reflected according to the detected reactor temperature.
- the detector sensitivity of the self-powered neutron detector can be corrected with higher accuracy.
- the calculation unit is The reaction cross-sectional area of the self-powered detector is a function indicating the change in the reaction cross-sectional area at each measurement time due to the Doppler effect accompanying temperature changes, or the reaction cross-sectional area corresponding to the temperature of the nuclear reactor is calculated at each temperature. data discretized to , corrected based on It is.
- the function indicating the change in the reaction cross section at each measurement time due to the Doppler effect accompanying the temperature change, or the reaction cross section corresponding to the temperature of the reactor is discretized for each temperature.
- FIG. 7 is a configuration diagram of the learning device 14 included in the calculation unit 10 relating to the neutron flux measuring device according to the third embodiment.
- the computing unit 10 further includes a learning device 14 and an inference device 15, which will be described below.
- the learning device 14 includes a data acquisition unit 14a, a model generation unit 14b, and a learned model storage unit M. As shown in FIG. Each of these units will be described below.
- the data acquisition unit 14a acquires the first input signal S1, the second input signal S2, and the third input signal S3 as learning data.
- the first input signal S1 is a neutron flux measurement value output by the neutron flux counter 2 .
- the second input signal S2 is various plant parameters that indicate the operational state of the reactor.
- the various plant parameters indicating the operating state of the nuclear reactor indicated by the second input signal S2 are, for example, the adjustment control amount of the reactor output, the reactor temperature Ta, the amount of control rods inserted and withdrawn, the flow rate of the coolant in the reactor. , the boric acid concentration in the coolant, and other parameters related to the adjustment of reactor power. At least one such parameter is used for the second input signal S2.
- These parameters are related to form a neutron flux distribution in the nuclear reactor, and are parameters that affect the neutron dose of the self-powered neutron detector 1 . However, in general, it is difficult to uniquely relate it to the consumption of the emitter material 1a of the self-powered neutron detector 1.
- the third input signal S3 is the ideal detector sensitivity derived based on the theoretical calculation, and the sensitivity of the self-powered detector derived based on the calculations performed by the neutron flux measurement device in Embodiments 1 and 2. It is the detector sensitivity that does not depend on the degree of deterioration. Furthermore, this third input signal also includes the neutron flux that is derived based on the calculations performed by the neutron flux measurement apparatus in the first and second embodiments and does not depend on the degree of deterioration of the self-powered detector.
- the data acquisition unit 14a outputs the acquired first input signal S1, second input signal S2, and third input signal S3 to the model generation unit 14b as learning data. Based on the first input signal S1, the second input signal S2, and the third input signal S3 output from the data acquisition unit 14a, the model generation unit 14b receives the measured value of the neutron flux and the reactor learning the detector sensitivity and neutron flux that do not depend on the degree of deterioration of the self-powered detector 1 corresponding to the operating state of .
- the neutron flux counting unit 2 determines whether various plant parameters, and the ideal detector sensitivity and neutron flux based on theoretical calculations, detection that does not depend on the degree of deterioration of the self-powered detector 1 Generate a trained model Mo that infers instrument sensitivity and neutron flux.
- the first input signal S1, the second input signal S2, and the third input signal S3 are the neutron flux output from the neutron flux counter 2, various plant parameters indicating the state of the reactor, and theoretical calculations.
- the ideal neutron flux based on this is the learning data associated with each other.
- a general-purpose neutron/photon transport calculation Monte Carlo code capable of critical calculation such as MVP (onte Carlo codes ), MCNP (Monte Carlo N-Particle code), etc., as well as deterministic methods based on neutron transport equations and neutron diffusion equations.
- the core model is reproduced including the types and arrangements of the fuel assemblies constituting the nuclear reactor, as well as parameters related to adjustment of the output of the nuclear reactor, such as control rod positions.
- supervised learning unsupervised learning
- reinforcement learning can be used as the learning algorithm used by the model generation unit 14b.
- a case where a neural network is applied will be described.
- the model generator 14b learns the detector sensitivity and the neutron flux independent of the degree of deterioration of the detector by so-called supervised learning according to, for example, a neural network model.
- supervised learning refers to a method of inferring a result from an input by giving a set of input and result (label) data to the learning device 14 to learn features in the learning data.
- a neural network consists of an input layer consisting of multiple neurons, an intermediate layer (hidden layer) consisting of multiple neurons, and an output layer consisting of multiple neurons.
- the intermediate layer may be one layer, or two or more layers.
- the neural network receives the first input signal S1, which is the neutron flux output by the neutron flux counting unit 2, which is acquired by the data acquisition unit 14a, and the second input signal, which is various plant parameters.
- the learning data created based on the combination of S2 and the third input signal S3, which indicates the ideal detector sensitivity and neutron flux based on theoretical calculation so-called supervised learning is performed to determine the degree of deterioration of the detector. Learn independent detector sensitivity and neutron flux.
- the neutron flux output by the neutron flux counting unit 2 and various plant parameters are input to the input layer, and the results output from the output layer are ideal detection values based on theoretical calculations, Learning is performed by adjusting the weights W1 and W2 so as to approach the neutron flux.
- FIG. 9 is a flowchart relating to learning processing of the learning device 14 according to the third embodiment.
- the data acquisition unit 14a acquires the first input signal S1, the second input signal S2, and the third input signal S3 during the first set period T1.
- first input signal S1, the second input signal S2, and the third input signal S3 are not limited to being obtained at the same time. It suffices if the first input signal S1, the second input signal S2, and the third input signal S3 can be input in association with each other, and may be obtained at different timings.
- step s12 the model generation unit 14b generates supervised data based on the learning data based on the combination of the first input signal S1, the second input signal S2, and the third input signal S3 acquired by the data acquisition unit 14a.
- the detector sensitivity independent of the degree of deterioration of the self-powered neutron detector and the neutron flux are learned, and the trained model Mo is generated.
- the learned model storage unit M stores the learned model Mo generated by the model generation unit 14b.
- the neutron flux output by the neutron flux counter 2 various plant parameters indicating the state of the reactor, and the ideal neutron flux based on theoretical calculations are associated with each other for learning. and the trained model Mo is generated and stored.
- FIG. 10 is a diagram showing the configuration of the inference device 15 relating to the neutron flux measurement device according to Embodiment 1. As shown in FIG.
- the inference device 15 includes a data acquisition unit 15a and an inference unit 15b.
- the data acquisition unit 15a acquires the first input signal S1 indicating the neutron flux output from the neutron flux counting unit 2 and the second input signal S2 that is various plant parameters in the second set period T2, and the inference unit 15b.
- the inference unit 15b calculates the detector sensitivity independent of the deterioration degree of the self-powered neutron detector 1 obtained by using the trained model Mo. and infer the neutron flux. That is, by using the trained model Mo, from the first input signal S1 indicating the neutron flux output by the neutron flux counting unit 2 acquired by the data acquisition unit 15a and the second input signal S2, which is various plant parameters, , the detector sensitivity and neutron flux independent of the degree of deterioration of the self-powered neutron detector 1 can be output.
- FIG. 11 is a flowchart of learning processing of the inference device 15 according to the third embodiment.
- step s21 the data acquisition unit 15a obtains the first input signal S1 indicating the neutron flux output by the neutron flux counting unit 2 and the reactor operation and a second input signal S2 indicative of various plant parameters indicative of the state.
- step s22 the inference unit 15b inputs the first input signal S1 and the second input signal S2 to the trained model Mo stored in the trained model storage unit M, and the self-powered neutron detector 1 We obtain detector sensitivity and neutron flux that do not depend on the degree of degradation of .
- the inference unit 15b outputs the detector sensitivity and neutron flux independent of the degree of deterioration of the self-powered neutron detector 1 obtained from the trained model Mo to the host device 3.
- supervised learning is applied to the learning algorithm used by the model generation unit 14b, but the present invention is not limited to this.
- the model generation unit 14b may learn neutron flux that does not depend on the degree of deterioration of the self-powered neutron detector 1 according to learning data created for a plurality of neutron flux measurement devices.
- the model generating unit 14b may acquire learning data from a plurality of neutron flux measuring devices used in the same area, or may acquire learning data from a plurality of neutron flux measuring devices operating independently in different areas. Detector sensitivity and neutron flux that do not depend on the degree of deterioration of the self-powered neutron detector 1 may be learned by using the learning data.
- the neutron flux measuring device that collects learning data from the target during the process.
- a learning device that has learned neutron flux that does not depend on the degree of deterioration of the self-powered neutron detector 1 with respect to a certain neutron flux measuring device is applied to another neutron flux measuring device, and the other neutron flux measuring device The neutron flux that does not depend on the degree of deterioration of the self-powered neutron detector 1 may be re-learned and updated.
- Deep learning Deep Learning
- Other known methods such as genetic programming, functional logic programming, support Machine learning may be performed according to a vector machine or the like.
- the learning device and the inference device are used to learn the detector sensitivity and neutron flux that do not depend on the degree of deterioration of the self-powered neutron detector of the neutron flux measurement device. It may be a device connected to the measuring device and separate from the neutron flux measuring device. Also, the learning device and the reasoning device may be incorporated in the neutron flux measuring device. Furthermore, the learning device and reasoning device may reside on a cloud server.
- the neutron flux that does not depend on the degree of deterioration of the self-powered neutron detector 1 is output using the learned model learned by the model generation unit of the neutron flux measurement device.
- a trained model may be acquired from an external device such as a neutron flux measuring device, and a neutron flux independent of the degree of deterioration of the self-powered neutron detector 1 may be output based on this trained model.
- FIG. 12 is a diagram showing an example of the hardware configuration of the computing unit 10 according to the third embodiment.
- the hardware of the computing unit 10 is composed of a processor 16A and a storage device 16B, as shown in FIG.
- the storage device 16B includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory (not shown). Also, an auxiliary storage device such as a hard disk may be provided instead of the flash memory.
- the processor 16A executes programs input from the storage device 16B. In this case, the program is input from the auxiliary storage device to the processor 16A via the volatile storage device. Further, the processor 16A may output data such as calculation results to the volatile storage device of the storage device 16B, or may store the data in the auxiliary storage device via the volatile storage device.
- the neutron flux measurement device of this embodiment configured as described above is
- the calculation unit is a first input signal output by the self-powered detector of the neutron flux measurement device that detects neutrons in the nuclear reactor during the first set period; a second input signal indicating the operating state of the reactor during the first set period; a data acquisition unit for acquiring learning data including a third input signal indicating detector sensitivity and neutron flux of the self-powered detector corresponding to the first input signal and the second input signal; Using the learning data, from the first input signal and the second input signal in the second set period after the first set period, the number of neutrons of the self-powered detector in the second set period a model generator that generates a trained model for inferring detector sensitivity and neutron flux;
- the detector sensitivity and neutron flux of the self-powered detector used for the third input signal are derived by the control by the arithmetic unit of the neutron flux measuring device according to Embodiments 1 and 2, It is.
- the calculation unit is an inference unit that outputs neutron detector sensitivity and neutron flux of the self-powered detector in the second set period from the first input signal and the second input signal using the trained model. , It is.
- the neutron flux measurement device includes the measured value of the neutron flux output by the neutron flux counter during the first set period in the past, various plant parameters indicating the operating state of the reactor during the first set period in the past, From the ideal detector sensitivity and neutron flux derived based on theoretical calculations, the detector sensitivity and neutron flux that do not depend on the degree of deterioration of the self-powered detector are learned. Then, from the measured value of the neutron flux output by the neutron flux counter during the subsequent second set period and various plant parameters indicating the operating state of the reactor during this second set period, the self-powered detector is determined. Degradation-independent detector sensitivity and neutron flux can be inferred. In this way, a neutron flux measurement device is obtained with improved throughput and capable of inferring accurate detector sensitivity and neutron flux.
- 1 Self-powered neutron detector 2 neutron flux counting unit, 10 computing unit, 12 neutron flux storage unit (storage unit), 100, 200 neutron flux measuring device.
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Abstract
Description
Sn=Sn-1・exp(-σ)・φn-1・Δt
Sn:時刻tn-1=tn-Δtllにおける自己出力型中性子検出器の中性子感度
Sn-1:時刻t-1=tn-Δtにおける自己出力型中性子検出器の中性子感度
σ:自己出力型中性子検出器のエミッタ物質の中性子吸収断面積
φn-1:時刻tn-1=tn-△tにおける中性子検出器位置での中性子束
なる式により自己出力型中性子検出器の中性子感度補正を行う補正手段を付加する(例えば、特許文献1参照)。
原子炉内における中性子を検出する自己出力型検出器と、
前記自己出力型検出器の出力に基づいて、前記原子炉内の中性子束を計測する中性子束計数部と、
第1設定期間における前記原子炉の出力の調整制御に応じた前記原子炉内の中性子束の変化を示す計測値を記録データとして記録する記憶部と、
前記記録データに基づいて、前記第1設定期間より後の第2設定期間における前記調整制御に応じて、該第2設定期間の経過時点である時点t1における前記自己出力型検出器の中性子の検出器感度の補正を行い、該補正された検出器感度を用いて前記時点t1における中性子束を導出する演算部と、を備えた、
ものである。
以下、原子炉内の中性子束の計測を行う本実施の形態の中性子束計測装置100について説明する。
図1は、実施の形態1による中性子束計測装置100の概略構成を示すブロック図である。
図1に示すように、中性子束計測装置100は、自己出力型検出器としての自己出力型中性子検出器1と、中性子束計数部2と、演算部10と、上位装置3と、を備える。
以下、中性子束計測装置100を構成するこれら各部の詳細について説明する。
図2は、図1に示した自己出力型中性子検出器1の概略構成を示す図である。
自己出力型中性子検出器1は、原子炉の炉心内に配置されて、炉心内の中性子を検出する。
図2に示すように、自己出力型中性子検出器1は、例えば、有感部の金属となるエミッタ材1aと、被覆材となるコレクタ材1bと、エミッタ材1aとコレクタ材1bとの間に配置される絶縁体1cと、エミッタ材1aとコレクタ材1bに各々接続される信号線1d、1eと、を備える。
なお、エミッタ材1aの金属材料としては、一般的に、中性子に対する放射化断面積の大きさ、放射化後の崩壊時定数、等の条件から、ロジウムまたはバナジウムの他、コバルトが用いられている。
中性子束計数部2は、自己出力型中性子検出器1が出力した電流を入力とし、入力された電流の大きさに基づいた中性子束への変換を行い、変換した中性子束を計数する機能を持つ。中性子束計数部2は、このように入力された電流から中性子束への変換を行うために、以下式(1)による計算を行う。
φは、単位時間に単位面積を通過した中性子数、あるいは、単位時間に単位体積中の中性子が走った距離の総和を示す中性子束を表す。
Iは、自己出力型中性子検出器1が出力した電流の値を表す。
Sは、自己出力型中性子検出器1からの電流を中性子束密度で除した、自己出力型中性子検出器1の検出器感度を表す。
Φ’は、計測開始時刻(時点t0)において中性子束計数部2で計測された中性子束の値を表す。
なお、以下の説明では、時点t0から計測期間T2が経過した時点t1は、現在時刻として記載する。
以下、自己出力型中性子検出器1の検出器感度を補正する原理について説明する。
Nは自己出力型中性子検出器1のエミッタ材1aの放射化する原子数を表す。
σは、自己出力型中性子検出器1のエミッタ材1aに入射した粒子が、エミッタ材1a中の原子核と反応を起こす確率を示す反応断面積を表す。
Φは、自己出力型中性子検出器1のエミッタ材1aに入る中性子束を表す。
Sは、現在時刻(時点t1)における自己出力型中性子検出器1の検出器感度を表す。
Kは、自己出力型中性子検出器1の検出器感度と自己出力型中性子検出器1のエミッタ材1aの原子数との比例係数を表す。
ここで、自己出力型中性子検出器1の検出器感度の補正をするための演算は、以下式(6)により表すことができる。
本図において、中性子束の計測を行う計測間隔Δtを、原子炉出力もしくは原子炉内の中性子束が変化する時間よりも短くした場合で補正を行った検出器感度Ssと、長くした場合で補正を行った検出器感度Slと、を示す。
本実施の形態の演算部10は、以下に説明するように、中性子束の計測期間T2中における中性子束の計測間隔Δtを、原子炉内の中性子束が変化する時間よりも短くすることで、中性子束の計測を高精度化する。
図1に戻り、演算部10は、中性子束補正演算部11と、中性子束記憶部12と、検出器感度補正演算部13と、を備える。
中性子束記憶部12は、検出された中性子束の値を記憶保持する機能を持ち、例えばメモリ、ハードディスク、外付けの記憶媒体、等が用いられ、記憶する記録データの量に応じた記憶媒体が選定されて構成される。
検出器感度補正演算部13は、中性子束記憶部12に記録された記録データDに基づいて、現在時刻(時点t1)における自己出力型中性子検出器1の検出器感度の補正を行う。
前述のように、中性子束記憶部12が記録している記録データDは、過去の第1設定期間T1において計数した、原子炉の出力の調整制御に応じた原子炉内の中性子束の計数値の変化を示すものである。
以上のように、検出器感度補正演算部13は、原子炉の出力調整制御に応じて変化する中性子束の時間間隔Δtcよりも短い計測間隔Δt毎に計測された複数の中性子束を用いて、現在時刻(時点t1)における検出器感度を精度良く導出する。
中性子束補正演算部11は、中性子束計数部2から入力された中性子束に対して、検出器感度補正演算部13から入力された補正済の検出器感度の変化の分を補正して中性子束を演算する。
中性子束補正演算部11は、検出器感度補正演算部13から伝達される、補正済みの現在時刻(時点t1)における検出器感度を用い、以下、(8)式に従って、中性子束計数部2から入力された中性子束の値を補正する。
Φは、中性子束計数部2で計測された補正済みの中性子束の値を表す。
Φ’は、中性子束計数部2で計測された補正前の中性子束の値を表す。
中性子束記憶部12は、補正した現在時刻(時点t1)における中性子束を記録データD内に記録し、現在時刻(t1)より後の中性子束の補正において用いる。
上位装置3は、中性子束補正演算部11から伝達される中性子束を処理する装置であり、例えば原子炉制御用のコンピュータ、原子炉状態監視用の表示画面等である。
原子炉内における中性子を検出する自己出力型検出器と、
前記自己出力型検出器の出力に基づいて、前記原子炉内の中性子束を計測する中性子束計数部と、
第1設定期間における前記原子炉の出力の調整制御に応じた前記原子炉内の中性子束の変化を示す計測値を記録データとして記録する記憶部と、
前記記録データに基づいて、前記第1設定期間より後の第2設定期間における前記調整制御に応じて、該第2設定期間の経過時点である時点t1における前記自己出力型検出器の中性子の検出器感度の補正を行い、該補正された検出器感度を用いて前記時点t1における中性子束を導出する演算部と、を備えた、
ものである。
こうして、計測期間である第2設定期間において原子炉の出力が調整制御により頻繁に変動する場合でも、この原子炉の調整制御による中性子の照射量の変動に応じた検出器感度の補正を行える。そのため、中性子の照射量の変動による自己出力型検出器の劣化度合いの変動に依存しない、精度よい中性子束を得られる。
また、校正用検出器を炉内に別途配置する必要がないために、機器点数を増加させず、機器の保守、保全業務を不要とでき、コスト削減を図れる。
前記演算部は、
前記記録データに基づいて、前記第2設定期間における前記原子炉の前記調整制御に応じた前記原子炉内の中性子束の計数が変化する時間間隔Δtcを推測し、
前記時間間隔Δtcに基づいて、前記第2設定期間における前記中性子束計数部による計測間隔Δtを調整して、前記時点t1における前記自己出力型検出器の検出器感度の補正を行う、
ものである。
そしてこの精度よく推測された中性子束が変化する時間間隔Δtcに基づいて、計測期間における計測間隔Δtを調整することで、原子炉の出力の調整制御による中性子の照射量の変動に応じた検出器感度の精度良い補正を行える。
前記計測間隔Δtは、推測される前記時間間隔Δtcよりも短く設定される、
ものである。
前記演算部は、
前記時点t1における前記自己出力型検出器の検出器感度を、前記第2設定期間の計測開始時点である時点t0における前記自己出力型検出器の検出器感度を用いて、以下式に基づき導出し、
但し、
Sは、前記時点t1における前記自己出力型検出器の検出器感度であり、
S0は、前記時点t0における前記自己出力型検出器の検出器感度であり、
σは、前記自己出力型検出器の、中性子との反応断面積であり、
φは、前記計測間隔ごとの計測時点における中性子束であり、
前記演算部は、
前記時点t1における前記自己出力型検出器の検出器感度の補正において、
前記第2設定期間内において計測された全ての前記計測時点における中性子束を用いる、
ものである。
計測期間である第2設定期間内において計測された、全ての計測間隔Δt毎の計測時点における中性子束を用いて、現在時刻である時点t1における自己出力型検出器の検出器感度の補正を行う。
このように、計測間隔Δt毎に計測された全ての中性子束を用い、大幅な近似を行う演算を行わないため、補正誤差の積み重ねが増大することを抑制でき、精度よい検出器感度の補正が行える。
以下、本実施の形態2の中性子束計測装置200について、実施の形態1と異なる部分を中心に図を用いて説明する。実施の形態1と同様の部分は同一符号を伏して説明を省略する。
図4は、実施の形態2による中性子束計測装置200の概略構成を示すブロック図である。
図4に示すように、本実施の形態の検出器感度補正演算部13には、原子炉内の炉内温度Taが入力される。そして検出器感度補正演算部13は、入力される原子炉内の炉内温度Taに基づいた自己出力型検出器の反応面積の温度依存性を反映した検出器感度の補正を行う。
なお、炉内温度Taは、例えば、温度計から感度補正演算部に直接入力する他、一旦、上位装置3に集約された炉内温度Ta、または、炉心シミュレータ等によって算出された炉内温度Taでも良い。
図5は、一般的な自己出力型中性子検出器1に用いられるエミッタ材1aのロジウムとバナジウムの中性子捕獲の反応断面積の変化を示す図である。
図6は、反応断面積の温度依存性を示す模式図である。
図6において、低温時の反応断面積σ21と、高温時の反応断面積σ22とが示されている。
例えば、自己出力型中性子検出器1のエミッタ材1aにロジウムを用いる場合は、図6に示すように、特定の中性子エネルギ帯に特徴的なピーク形状をもつ共鳴吸収ピークと呼ばれるエネルギ帯の反応断面積は、ドップラー効果の持つ温度依存性によってその形状が変化する。したがって、低温時の反応断面積σ21から炉内温度が上昇することで、高温時の反応断面積σ22となるため、炉内温度Taが上昇することでドップラー効果の影響により、中性子と相互反応する確率が増加し、低温時に比べエミッタ材1aの消耗が早まり検出器感度が低下する。
前記原子炉の炉内温度を検出する温度検出器を備え、
前記演算部は、前記温度検出器により検出された温度に応じて、前記自己出力型検出器の中性子の反応断面積の値を補正する、
ものである。
前記演算部は、
前記自己出力型検出器の反応断面積は、温度変化に伴うドップラー効果による前記計測時点毎の反応断面積の変化を示す関数、あるいは、前記原子炉の温度に対応する反応断面積を該温度毎に離散化したデータ、に基づいて補正する、
ものである。
以下、本実施の形態3の中性子束計測装置について、実施の形態2と異なる部分を中心に図を用いて説明する。実施の形態2と同様の部分は同一符号を伏して説明を省略する。
図7は、実施の形態3による中性子束計測装置に関する演算部10が備える学習装置14の構成図である。
先ず、学習装置14の構成について説明する。
図7に示すように、学習装置14は、データ取得部14aと、モデル生成部14bと、学習済モデル記憶部Mとを備える。以下、これら各部について説明する。
第1入力信号S1は、中性子束計数部2が出力する中性子束の計測値である。
第2入力信号S2には、このようなパラメータが少なくとも一つ以上用いられる。
なお、これらのパラメータは、原子炉内における中性子束の分布を成すために関連しており、自己出力型中性子検出器1の中性子照射量に影響するパラメータではある。しかしながら、一般的には、自己出力型中性子検出器1のエミッタ材1aの消耗と一意に関連させることは困難である。
更に、この第3入力信号は、実施の形態1、2における中性子束計測装置が行った演算に基づき導出されたた自己出力型検出器の劣化度合いに依存しない中性子束も含む。
モデル生成部14bは、データ取得部14aから出力される第1入力信号S1と、第2入力信号S2と、第3入力信号S3と、に基づいて、入力される中性子束の計測値および原子炉の運転状態に対応する、自己出力型検出器1の劣化度合いに依存しない検出器感度および中性子束を学習する。
以上のように、第1入力信号S1、第2入力信号S2、第3入力信号S3は、中性子束計数部2が出力する中性子束、原子炉の状態を示す種々のプラントパラメータ、および理論計算に基づいた理想的な中性子束、を互いに関連付けた学習用データである。
なお、炉心モデルとしては、原子炉を構成する燃料集合体の種類、配置の他、制御棒位置などの前記原子炉の出力の調整に関するパラメータを含み再現されている。
ここで、教師あり学習とは、入力と結果(ラベル)のデータの組を学習装置14に与えることで、それらの学習用データにある特徴を学習し、入力から結果を推論する手法をいう。
すなわち、ニューラルネットワークは、入力層に前記中性子束計数部2が出力する中性子束と、種々のプラントパラメータを入力して出力層から出力された結果が、理論計算に基づいた理想的な検出値、中性子束に近づくように重みW1とW2を調整することで学習する。
図9は、実施の形態3による学習装置14の学習処理に関するフローチャートである。
先ず、ステップs11において、データ取得部14aは、第1設定期間T1における、第1入力信号S1と、第1設定期間T1における第2入力信号S2と、第3入力信号S3とを取得する。
図10は、実施の形態1による中性子束計測装置に関する推論装置15の構成を示す図である。
推論装置15は、データ取得部15aと、推論部15bとを備える。
すなわち、学習済モデルMoを用いることで、データ取得部15aで取得した中性子束計数部2が出力する中性子束を示す第1入力信号S1と、種々のプラントパラメータである第2入力信号S2とから、自己出力型中性子検出器1の劣化度合いに依存しない検出器感度と中性子束を出力することができる。
図11は、実施の形態3による推論装置15の学習処理に関するフローチャートである。
なお、モデル生成部14bは、同一のエリアで使用される複数の中性子束計測装置から学習用データを取得してもよいし、異なるエリアで独立して動作する複数の中性子束計測装置から収集される学習用データを利用して自己出力型中性子検出器1の劣化度合いに依存しない検出器感度と中性子束を学習してもよい。
さらに、ある中性子束計測装置に関して自己出力型中性子検出器1の劣化度合いに依存しない中性子束を学習した学習装置を、これとは別の中性子束計測装置に適用し、当該別の中性子束計測装置に関して自己出力型中性子検出器1の劣化度合いに依存しない中性子束を再学習して更新するようにしてもよい。
また、学習装置及び推論装置は、中性子束計測装置に内蔵されていてもよい。さらに、学習装置及び推論装置は、クラウドサーバ上に存在していてもよい。
なお、演算部10のハードウエアは、その構成の一例を図12に示すように、プロセッサ16Aと記憶装置16Bから構成される。記憶装置16Bは、図示していない、ランダムアクセスメモリ等の揮発性記憶装置と、フラッシュメモリ等の不揮発性の補助記憶装置とを備える。
また、フラッシュメモリの代わりにハードディスクの補助記憶装置を備えてもよい。プロセッサ16Aは、記憶装置16Bから入力されたプログラムを実行する。この場合、補助記憶措置から揮発性記憶装置を介してプロセッサ16Aにプログラムが入力される。また、プロセッサ16Aは、演算結果等のデータを記憶装置16Bの揮発性記憶装置に出力してもよいし、揮発性記憶装置を介して補助記憶装置にデータを保存してもよい。
前記演算部は、
前記第1設定期間における、前記原子炉内の中性子を検出する前記中性子束計測装置の前記自己出力型検出器が出力する第1入力信号と、
前記第1設定期間における、前記原子炉の運転状態を示す第2入力信号と、
前記第1入力信号および前記第2入力信号に対応する前記自己出力型検出器の検出器感度および中性子束を示す第3入力信号と、を含む学習用データを取得するデータ取得部と、
前記学習用データを用いて、前記第1設定期間より後の前記第2設定期間における前記第1入力信号および前記第2入力信号から、前記第2設定期間における前記自己出力型検出器の中性子の検出器感度および中性子束を推論するための学習済モデルを生成するモデル生成部と、を備え、
前記第3入力信号に用いられる前記自己出力型検出器の検出器感度および中性子束は、実施の形態1から2に記載の中性子束計測装置の前記演算部による制御により導出される、
ものである。
前記演算部は、
前記学習済モデルを用いて、前記第1入力信号および前記第2入力信号から、前記第2設定期間における前記自己出力型検出器の中性子の検出器感度および中性子束を出力する推論部、を備える、
ものである。
そして、その後の第2設定期間において中性子束計数部が出力した中性子束の計測値とと、この第2設定期間における原子炉の運転状態を示す種々のプラントパラメータとから、自己出力型検出器の劣化度合いに依存しない検出器感度および中性子束を推論できる。
こうして、処理能力が向上され、精度良い検出器感度および中性子束を推論できる中性子束計測装置が得られる。
従って、例示されていない無数の変形例が、本願に開示される技術の範囲内において想定される。例えば、少なくとも1つの構成要素を変形する場合、追加する場合または省略する場合、さらには、少なくとも1つの構成要素を抽出し、他の実施の形態の構成要素と組み合わせる場合が含まれるものとする。
Claims (8)
- 原子炉内における中性子を検出する自己出力型検出器と、
前記自己出力型検出器の出力に基づいて、前記原子炉内の中性子束を計測する中性子束計数部と、
第1設定期間における前記原子炉の出力の調整制御に応じた前記原子炉内の中性子束の変化を示す計測値を、記録データとして記録する記憶部と、
前記記録データに基づいて、前記第1設定期間より後の第2設定期間における前記調整制御に応じて、該第2設定期間の経過時点である時点t1における前記自己出力型検出器の中性子の検出器感度の補正を行い、該補正された検出器感度を用いて前記時点t1における中性子束を導出する演算部と、を備えた、
中性子束計測装置。 - 前記演算部は、
前記記録データに基づいて、前記第2設定期間における前記原子炉の前記調整制御に応じた前記原子炉内の中性子束の計数が変化する時間間隔Δtcを推測し、
前記時間間隔Δtcに基づいて、前記第2設定期間における前記中性子束計数部による計測間隔Δtを調整して、前記時点t1における前記自己出力型検出器の検出器感度の補正を行う、
請求項1に記載の中性子束計測装置。 - 前記計測間隔Δtは、前記演算部により推測される前記時間間隔Δtcよりも短く設定される、
請求項2に記載の中性子束計測装置。 - 前記演算部は、
前記時点t1における前記自己出力型検出器の検出器感度を、前記第2設定期間の計測開始時点である時点t0における前記自己出力型検出器の検出器感度を用いて、以下(1)式に基づき導出し、
但し、
Sは、前記時点t1における前記自己出力型検出器の検出器感度であり、
S0は、前記時点t0における前記自己出力型検出器の検出器感度であり、
σは、前記自己出力型検出器の、中性子との反応断面積であり、
φは、前記計測間隔ごとの計測時点における中性子束であり、
前記演算部は、
前記時点t1における前記自己出力型検出器の検出器感度の補正において、
前記第2設定期間内において計測された全ての前記計測時点における中性子束を用いる、
請求項2または請求項3に記載の中性子束計測装置。 - 前記原子炉の炉内温度を検出する温度検出器を備え、
前記演算部は、前記温度検出器により検出された温度に応じて、前記自己出力型検出器の中性子の反応断面積の値を補正して、該補正された反応断面積を用いて前記時点t1における前記自己出力型検出器の中性子の検出器感度の補正を行う、
請求項4に記載の中性子束計測装置。 - 前記演算部は、
前記自己出力型検出器の反応断面積は、温度変化に伴うドップラー効果による前記計測時点毎の反応断面積の変化を示す関数、あるいは、前記原子炉の温度に対応する反応断面積を該温度毎に離散化したデータ、に基づいて補正する、
請求項4または請求項5に記載の中性子束計測装置。 - 前記演算部は、
前記第1設定期間における、前記原子炉内の中性子を検出する前記中性子束計測装置の前記自己出力型検出器が出力する第1入力信号と、
前記第1設定期間における、前記原子炉の運転状態を示す第2入力信号と、
前記第1入力信号および前記第2入力信号に対応する前記自己出力型検出器の検出器感度および中性子束を示す第3入力信号と、を含む学習用データを取得するデータ取得部と、
前記学習用データを用いて、前記第1設定期間より後の前記第2設定期間における前記第1入力信号および前記第2入力信号から、前記第2設定期間における前記自己出力型検出器の中性子の検出器感度および中性子束を推論するための学習済モデルを生成するモデル生成部と、を備え、
前記第3入力信号に用いられる前記自己出力型検出器の検出器感度および中性子束は、請求項1から請求項6のいずれか1項に記載の中性子束計測装置の前記演算部による制御により導出される、
中性子束計測装置。 - 前記演算部は、
前記学習済モデルを用いて、前記第1入力信号および前記第2入力信号から、前記第2設定期間における前記自己出力型検出器の中性子の検出器感度および中性子束を出力する推論部、を備える、
請求項7に記載の中性子束計測装置。
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