A reactor neutron detector calibration method, system and computer device

Abstract

The application discloses a reactor neutron detector calibration method, system and computer equipment, relates to the nuclear reactor core monitoring technical field, and is based on the absolute neutron flux at a position of a reactor core measured by an activation method, combines the neutron flux distribution relation inside and outside the reactor, maps the absolute neutron flux at the position of the neutron detector outside the reactor, obtains the corresponding relation between the neutron detector measurement result and the absolute neutron flux at the neutron detector, and based on the corresponding relation and the neutron detector measurement result, the absolute neutron flux at the detector can be quickly and accurately obtained. The application only uses the activation method to calibrate the conversion factor of the neutron detector once, and under various conditions such as changes in the core arrangement, changes in the core control rod state, changes in the core power and the like, the absolute neutron flux at the detector can be directly obtained through the measurement result of the neutron detector, and multiple irradiation experiments are not needed, so that the measurement efficiency is improved, and the cost is saved.

Description

Technical Field

[0001] This application relates to the field of nuclear reactor core monitoring technology, specifically to a reactor neutron detector calibration method, system, and computer equipment. Background Technology

[0002] Once the neutron detectors are manufactured domestically and internationally, only the range of detector sensitivity values ​​will be provided. The conversion factor between the detector measurement results and the neutron flux will not be accurately given. In other words, the absolute neutron flux at the detector cannot be determined from the detector measurement results. At this time, the change trend of the reactor core state can only be determined based on the detector measurement results, but it is impossible to determine important physical parameters that characterize the actual operating state of the reactor, such as the absolute neutron flux and absolute power of the reactor core.

[0003] The traditional method involves arranging activation sheets within the reactor core using an activation method. After irradiating the core for a certain period, the activity is measured, and parameters such as the absolute neutron flux or absolute power of the core are calculated. However, with this traditional method, if the core arrangement changes, multiple irradiation experiments using the activation method are required to determine the absolute neutron flux and absolute power. Furthermore, if the core power is increased or decreased, altering the flux level, the absolute neutron flux and absolute power previously determined using the activation method become inapplicable. Summary of the Invention

[0004] To address the problems of traditional methods, this application proposes a reactor neutron detector calibration method, system, and computer equipment. Based on the absolute neutron flux at a specific location in the reactor core measured using the activation method, and combined with the neutron flux distribution relationship inside and outside the reactor core, this application maps the absolute neutron flux at the location of the external neutron detector, establishing a correspondence between the neutron detector measurement results and the absolute neutron flux at the detector. Based on this correspondence and the neutron detector measurement results, the absolute neutron flux at the detector can be quickly and accurately determined. This application calibrates the neutron detector's conversion factor only once using the activation method. Subsequently, under various conditions such as changes in core arrangement, changes in core control rod states, and changes in core power, the absolute neutron flux at the detector can be obtained from the neutron detector measurement results. Furthermore, by analyzing the neutron flux distribution relationship inside and outside the reactor core, physical parameters characterizing the actual operating state of the core, such as the absolute core flux distribution and absolute core power, can be determined. This eliminates the need for multiple irradiation experiments, improving measurement efficiency and saving costs.

[0005] This application is achieved through the following technical solution:

[0006] A calibration method for a reactor neutron detector, the calibration method comprising:

[0007] The ratio between the normalized calculated neutron flux at the activated plate location and the normalized calculated neutron flux at the neutron detector location was obtained using core physics calculation and analysis software.

[0008] The absolute value of the neutron flux at the location of the activated plate is obtained by measuring the activation method, and the absolute value of the neutron flux at the location of the neutron detector is obtained according to the aforementioned proportional relationship;

[0009] Based on the neutron detector measurement results and the absolute value of the neutron flux at the location of the neutron detector, the neutron detector conversion factor is calibrated.

[0010] The neutron detector conversion factor is the ratio of the neutron detector measurement result to the absolute value of the neutron flux at the neutron detector location.

[0011] In some embodiments, the ratio between the normalized neutron flux at the activated plate location and the normalized neutron flux at the neutron detector location, calculated using core physics calculation and analysis software, specifically includes:

[0012] Based on the specific arrangement and material composition of the reactor core components, activation plates, neutron detectors, and reactor vessel, a theoretical calculation model is established using the core physics calculation and analysis software.

[0013] The established theoretical calculation model was checked and verified using typical critical rod positions in the reactor core obtained through actual reactor measurements.

[0014] Based on the actual critical rod position status of the reactor, adjust the positions of the safety rods and other control rods in the theoretical calculation model after verification and validation, so that the position status of all control rods in the theoretical calculation model is consistent with the measured position status of the reactor rods.

[0015] After the rod positions are adjusted to be consistent, initial parameters are set and parallel calculations are performed to obtain the normalized calculated value of neutron flux at the position of the activated plate and the normalized calculated value of neutron flux at the position of the neutron detector. The calculation deviation is controlled within a preset range.

[0016] The ratio between the normalized calculated neutron flux at the location of the activated plate and the normalized calculated neutron flux at the location of the neutron detector is obtained.

[0017] In some implementations, the theoretical calculation model is established in an order from inside to outside and from small to large, sequentially describing the fuel grid, fuel assembly, core, core shroud, reflector, and reactor vessel, and accurately modeling the activated sheet and neutron detector according to their actual size and spatial position.

[0018] In some embodiments, the method of measuring the absolute value of the neutron flux at the location of the activated plate using the activation method, and obtaining the absolute value of the neutron flux at the location of the neutron detector according to the stated proportional relationship, specifically includes:

[0019] After the activated sheet is irradiated in the reactor core, the absolute value of the neutron flux at the location of the activated sheet is measured using a gamma spectrometer and an absolute neutron flux measurement system.

[0020] Based on the reactor core power distribution characteristics and the synchronous fluctuation characteristics under the same core conditions, the following relationship is obtained: the ratio of the normalized calculated value of neutron flux at the activated plate location to the normalized calculated value of neutron flux at the neutron detector location is equal to the ratio of the absolute value of neutron flux at the activated plate location to the absolute value of neutron flux at the neutron detector location.

[0021] The absolute value of the neutron flux at the location of the neutron detector is obtained based on the absolute value of the neutron flux at the location of the activated plate and the aforementioned proportional relationship.

[0022] In some implementations, for neutron detectors of the neutron counting tube type, the neutron detector measures the number of counts.

[0023] In some implementations, for ionization chamber type neutron detectors, the neutron detector measures current values.

[0024] Secondly, this application proposes a reactor neutron detector calibration system, the calibration system comprising:

[0025] The model calculation module uses core physics calculation and analysis software to calculate the ratio between the normalized neutron flux at the activated sheet location and the normalized neutron flux at the neutron detector location.

[0026] The measurement and calculation module uses the activation method to measure the absolute value of the neutron flux at the location of the activation plate, and obtains the absolute value of the neutron flux at the location of the neutron detector according to the proportional relationship.

[0027] And, a conversion module, which calibrates the neutron detector conversion factor based on the neutron detector measurement results and the absolute value of the neutron flux at the neutron detector location;

[0028] The neutron detector conversion factor is the ratio of the neutron detector measurement result to the absolute value of the neutron flux at the neutron detector location.

[0029] In some implementations, the model calculation module further includes:

[0030] The model building unit establishes a theoretical calculation model using the reactor core physics calculation and analysis software based on the specific arrangement and material composition of the reactor core components, activation plates, neutron detectors, and reactor vessels.

[0031] The verification unit uses typical critical rod positions of the reactor core obtained through actual reactor measurements to check and verify the established theoretical calculation model.

[0032] The adjustment unit adjusts the positions of the safety rods and other control rods of the theoretical calculation model after verification and validation, according to the actual critical rod position state of the reactor, so that the position state of all control rods in the theoretical calculation model is consistent with the measured rod position state of the reactor.

[0033] In addition, there is an iterative calculation unit, which sets initial parameters, performs parallel calculations, and obtains the normalized calculated value of neutron flux at the activation plate position and the normalized calculated value of neutron flux at the neutron detector position, thereby obtaining the proportional relationship between the normalized calculated value of neutron flux at the activation plate position and the normalized calculated value of neutron flux at the neutron detector position.

[0034] Thirdly, this application proposes a computer device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described method.

[0035] Fourthly, this application proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0036] This application proposes a reactor neutron detector calibration method, system, and computer equipment. The conversion factor of the neutron detector is calibrated in one step using the activation method. Under various conditions such as changes in core arrangement, changes in core control rod state, and changes in core power, there is no need to restart the reactor for activation irradiation experiments. The absolute value of neutron flux at the neutron detector can be obtained directly by combining the measurement results of the neutron detector with the calibrated conversion factor. Furthermore, by analyzing the relationship between the neutron flux distribution inside and outside the reactor, physical parameters that characterize the actual operating state of the reactor core, such as the absolute flux distribution and absolute power of the core, can be determined.

[0037] The reactor neutron detector calibration method, system, and computer equipment proposed in this application can intuitively obtain absolute measurement values ​​that characterize the actual operating state of the reactor, such as the absolute neutron flux and absolute power of the reactor core, when using a calibrated neutron detector to monitor the core state or measure important physical parameters of the core. This eliminates the need to repeatedly open the reactor to measure the above parameters using the traditional activation method when the core layout or core state changes, thereby reducing the number of times the reactor needs to be opened, saving time, saving manpower, reducing personnel irradiation, and avoiding the use of activation sheets.

[0038] This application proposes a reactor neutron detector calibration method, system, and computer equipment, which reduces the wear and tear on the reactor and its supporting system equipment, and improves scientific research and production efficiency. Attached Figure Description

[0039] The accompanying drawings, which are included to provide a further understanding of the embodiments of this application and form part of this application, do not constitute a limitation on the embodiments of this application. In the drawings:

[0040] Figure 1 This is a schematic diagram of the gold sheet irradiation and activity change process according to an embodiment of this application; wherein, (a) is a schematic diagram of the gold sheet irradiation process; and (b) is a schematic diagram of the activity change process.

[0041] Figure 2 Examples of embodiments of this application 198 Au decay outline diagram;

[0042] Figure 3 This is a schematic diagram of the calibration method according to an embodiment of this application;

[0043] Figure 4 This is a schematic diagram of the arrangement of the reactor core activation sheet and neutron detector according to an embodiment of this application;

[0044] Figure 5 This is a neutron flux distribution diagram calculated according to an embodiment of this application;

[0045] Figure 6 This is a schematic diagram of the calibration system according to an embodiment of this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.

[0047] Example:

[0048] Traditional techniques for measuring reactor core neutron flux use activation methods. This involves placing activation plates within the reactor core, irradiating the core for a specific time, and then measuring the post-irradiation activity to calculate parameters such as absolute neutron flux or absolute power. Typical activation plates include Mn-Ni (manganese-nickel) plates and Au (gold) plates. Figure 1 The images show the irradiation process of gold flakes (a) and the changes in their activity (b).

[0049] The net growth rate of the radionuclide during irradiation is:

[0050]

[0051] In the formula, n(t) is a radioactive nuclide. 198 The number of nuclei in Au; φ0 is the thermal neutron flux with an energy of 0.025 eV, 1 / (cm²). 2 ·s); σ0 is 197 The thermal neutron micro-radiative capture cross section of Au, σ0=98.8b (1b=10 -24 cm 2 N is 197 Au is the number of atomic nuclei, a constant; λ is... 198 The decay constant of Au, s -1 , which represents the probability that an atomic nucleus will decay per unit of time.

[0052] Solving equation (1), substituting the initial conditions, i.e.: at t = t1 (ignoring the power increase stage), the activation product 198 The number of nuclei in Au is n(t) = 0. Therefore:

[0053]

[0054] At time t2 after irradiation ends 198 Number of Au nuclei:

[0055]

[0056] After the irradiation is completed, 198 Au is no longer generated; only decay occurs, and the half-life T decreases. 1 / 2 = 2.696 days, decay diagram see Figure 2 .

[0057] Therefore, the number of activated detector nuclei at time t after the irradiation ends:

[0058]

[0059] The radioactivity corresponding to equation (4) is:

[0060]

[0061] like Figure 1 As shown, the count of 0.412 MeV γ rays during the measurement time Δt from t3 to t4 is as follows:

[0062]

[0063] Solving equation (6), we can obtain:

[0064]

[0065] Where b is the background count rate, s -1 ;T L T represents the live time during gamma-ray spectrometer measurements, in seconds. R is the real time during the gamma-ray spectrometer measurement, in seconds; m0 is the mass of the activated plate, in mg; M is the relative atomic mass; N a is Avogadro's constant, 6.02 × 10⁻⁶. 23 mol -1 ε represents the absolute detection efficiency of the gamma-ray spectrometer for gamma rays; P γ for 198 The intensity of gamma rays during Au decay, P γ =95.5%.

[0066] make Equation (7) can then be simplified to:

[0067]

[0068] Equation (8) is the theoretical calculation formula required for measuring absolute neutron flux.

[0069] However, the above-mentioned traditional methods require repeated irradiation experiments to determine the absolute neutron flux and absolute power of the core when the core arrangement, the state of the core control rods, or the core power changes, resulting in low measurement efficiency and high cost.

[0070] To address this, this embodiment proposes a reactor neutron detector calibration method. The method proposed in this application calibrates the conversion factor of the neutron detector in one step using the activation method, and then directly obtains the absolute neutron flux at the detector based on the measurement results of the neutron detector and its corresponding conversion factor.

[0071] The reactor neutron detector involved in this embodiment includes a neutron counter tube and an ionization chamber, wherein the neutron counter tube includes a BF3 neutron counter tube. 3Neutron counters and ionization chambers include gamma-compensated ionization chambers and fission ionization chambers. Neutron counters are commonly used to provide neutron counting signals to reactor criticality extrapolation devices, criticality safety monitoring devices, and subcriticality measurement devices for reactor start-up criticality processes, reactor criticality safety monitoring, and reactor subcriticality measurement. Ionization chambers are commonly used to provide neutron current signals to reactor power measurement devices, power protection devices, cycle protection devices, and reactivity measurement instruments for reactor power measurement, overpower protection, short-cycle protection, and reactivity physical parameter measurement.

[0072] like Figure 3 As shown, the method proposed in this embodiment specifically includes the following steps:

[0073] Step 100: The ratio between the normalized neutron flux at the activated plate location and the normalized neutron flux at the neutron detector location is calculated using core physics calculation and analysis software.

[0074] Step 100 involves establishing a theoretical calculation model using high-precision core physics calculation and analysis software, based on the specific arrangement and material composition of the reactor core components and other components such as the activation plates, neutron detectors, and reactor vessel. The model is built sequentially from the inside out and from small to large, accurately describing the fuel grids, fuel assemblies, core, core shroud, reflector, and reactor vessel. The activation plates and neutron detectors are also precisely modeled according to their actual dimensions and spatial positions. Figure 4 As shown.

[0075] After the theoretical calculation model was established, the model was checked and verified using typical critical rod positions of the reactor core obtained from actual reactor measurements. Taking a certain reactor core as an example, Table 1 shows the theoretical calculation values ​​of the core multiplication factor for the typical critical rod positions and the corresponding critical rod positions. As can be seen from Table 1, the maximum deviation of the theoretical calculation values ​​is 2.8‰, and the calculation results of the established theoretical calculation model are quite accurate.

[0076] Table 1

[0077] bat position Measurement results Calculation results deviation(‰) Typical critical rod position A 1 0.99993 -0.07 Typical critical rod position B 1 1.00029 0.29 Typical critical rod position C 1 1.00176 1.76 Typical critical rod position D 1 0.99892 -1.08 Typical critical rod position E 1 1.00280 2.8 Typical critical rod position F 1 0.99917 -0.83 Typical critical rod position G 1 0.99941 -0.59

[0078] After establishing an accurate theoretical calculation model using core physics calculation and analysis software, the positions of the safety rods and other control rods in the theoretical calculation model are adjusted according to the actual critical rod position states of the reactor, so that the position states of all control rods in the theoretical calculation model are consistent with the measured rod position states of the reactor.

[0079] After the control rod positions of the theoretical calculation model are aligned, initial parameters are set, including the number of calculation iterations and the number of particles per calculation. Then, parallel calculations are performed to obtain the normalized calculated values ​​of neutron flux at the activated plate position and the normalized calculated values ​​of neutron flux at the neutron detector position, ensuring that the calculation deviation is controlled within 5%.

[0080] After calculating the normalized neutron flux at the activated plate location and the normalized neutron flux at the neutron detector location, the proportional relationship between the normalized neutron flux at the activated plate location and the neutron detector location can be expressed as:

[0081] α=Φ 归一活化 / Φ 归一探测

[0082] Where α represents the proportional relationship, Φ 归一活化 Φ represents the normalized calculated value of the neutron flux at the location of the activated plate. 归一探测 The normalized calculated value of neutron flux represents the location of the neutron detector.

[0083] By calculating multiple locations within the reactor core, we can obtain, for example... Figure 5 The diagram shows the neutron flux distribution.

[0084] Step 200: The absolute value of neutron flux at the location of the activated plate is measured using the activation method, and the absolute value of neutron flux at the location of the neutron detector is obtained according to the above proportional relationship.

[0085] Let the absolute value of the neutron flux at the activated plate location be Φ. 绝对活化 The absolute value of the neutron flux at the location of the neutron detector is Φ. 绝对探测 Based on the reactor core power distribution characteristics and the synchronous fluctuation characteristics of the core under the same conditions, it can be known that: α = Φ 归一活化 / Φ 归一探测 =Φ 绝对活化 / Φ 绝对探测 .

[0086] Based on this, step 200 uses an activation method to measure the absolute neutron flux at the location of the activated plate. After the activated plate is irradiated in the reactor core, the absolute value of the neutron flux at the location of the activated plate is measured using a gamma spectrometer and an absolute neutron flux measurement system. Therefore, based on the measured absolute value of the neutron flux at the location of the activated plate and the above relationship, the absolute value of the neutron flux at the location of the neutron detector can be obtained as follows:

[0087] Φ 绝对探测 =Φ 绝对活化 / α.

[0088] Step 300: Based on the neutron detector measurement results and the absolute value of the neutron flux at the neutron detector location, the neutron detector conversion factor is calibrated. The neutron detector conversion factor is the ratio of the neutron detector measurement results to the absolute value of the neutron flux at the neutron detector location.

[0089] The neutron detector conversion factor defined in this embodiment is the ratio of the neutron detector measurement result to the absolute value of the neutron flux at the location of the neutron detector. Let the neutron detector measurement result be R. 测量 The absolute value of the neutron flux at the location of the neutron detector is Φ. 绝对探测 Then the neutron detector conversion factor F 因子 =R 测量 / Φ 绝对探测 , where Φ 绝对探测 The unit is n / cm 2 ·s.

[0090] Among them, targeting BF3 neutron counters, 3 Neutron detectors of the He neutron counter tube type, and the measurement results collected by the neutron detector R 测量 Let n be the number of counts, then the neutron detector conversion factor F 因子 The unit is n / (n / cm) 2 ·s).

[0091] For neutron detectors of ionization chamber types such as gamma-compensated ionization chambers and fission ionization chambers, the measurement results R collected by the neutron detectors... 测量 Let F be the current value in amperes (A). Then the neutron detector conversion factor F... 因子 The unit is A / (n / cm) 2 ·s).

[0092] The calibration method proposed in this embodiment can calibrate the reactor neutron detector conversion factor in one step. Then, when using this neutron detector to monitor the core state or measure important core physical parameters, absolute measurements such as absolute neutron flux and absolute power, which characterize the actual operating state of the reactor, can be obtained directly. This eliminates the need for multiple reactor start-up irradiation experiments to measure these parameters when the core layout or state changes, thus reducing the number of reactor start-ups, saving time, manpower, and resources, reducing the impact of radiation on personnel, and avoiding the use of activation sheets. Furthermore, the calibration method proposed in this embodiment can also reduce damage to the reactor and its supporting system equipment, improving research and production efficiency.

[0093] Based on the same technical concept described above, this embodiment also proposes a reactor neutron detector calibration system, such as... Figure 6 As shown, the calibration system proposed in this embodiment specifically includes:

[0094] The model calculation module uses core physics calculation and analysis software to calculate the ratio between the normalized neutron flux at the activated sheet location and the normalized neutron flux at the neutron detector location.

[0095] The measurement and calculation module uses the activation method to measure the absolute value of the neutron flux at the location of the activation plate, and obtains the absolute value of the neutron flux at the location of the neutron detector according to the above proportional relationship.

[0096] In addition, there is a conversion module that calibrates the neutron detector conversion factor based on the neutron detector measurement results and the absolute value of the neutron flux at the neutron detector location. The neutron detector conversion factor is the ratio of the neutron detector measurement results to the absolute value of the neutron flux at the neutron detector location.

[0097] Furthermore, the model calculation module in this embodiment may also include:

[0098] The model building unit uses core physics calculation and analysis software capable of precise modeling to establish a theoretical calculation model based on the specific arrangement and material composition of the reactor core components and other components such as the activation sheet, neutron detector, and reactor vessel. The model building process follows an order from the inside out and from the small to the large, accurately describing the fuel grid elements, fuel assemblies, core, core shroud, reflector, and reactor vessel in sequence, and accurately modeling the activation sheet and neutron detector according to their actual size and spatial position.

[0099] The verification unit uses typical critical rod positions in the reactor core obtained through actual reactor measurements to check and verify the theoretical calculation model.

[0100] The adjustment unit adjusts the positions of the safety rods and other control rods in the theoretical calculation model according to the actual critical rod position state of the reactor, so that the position state of all control rods in the theoretical calculation model is consistent with the measured position state of the reactor rods.

[0101] In addition, there is an iterative calculation unit, which sets initial parameters, including the number of calculation iterations and the number of particles calculated in a single calculation, and then performs parallel calculations to obtain the normalized calculated value of neutron flux at the activated plate position and the normalized calculated value of neutron flux at the neutron detector position, thereby obtaining the ratio between the normalized calculated values ​​of neutron flux at the activated plate position and the neutron detector position.

[0102] It should be noted that the specific calculation process of the measurement calculation module and the conversion module in the above system is as described in steps 200 and 300 above, and will not be repeated here.

[0103] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0104] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0105] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0106] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0107] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for calibrating a reactor neutron detector, characterized in that, The calibration method includes: The ratio between the normalized calculated neutron flux at the activated plate location and the normalized calculated neutron flux at the neutron detector location was obtained using core physics calculation and analysis software. The absolute value of the neutron flux at the location of the activated plate is obtained by measuring the activation method, and the absolute value of the neutron flux at the location of the neutron detector is obtained according to the aforementioned proportional relationship; Based on the neutron detector measurement results and the absolute value of the neutron flux at the location of the neutron detector, the neutron detector conversion factor is calibrated. Wherein, the neutron detector conversion factor is the ratio of the neutron detector measurement result to the absolute value of the neutron flux at the neutron detector location; the ratio between the normalized calculated value of the neutron flux at the activated sheet location and the normalized calculated value of the neutron flux at the neutron detector location, obtained using core physics calculation and analysis software, specifically includes: Based on the specific arrangement and material composition of the reactor core components, activation plates, neutron detectors, and reactor vessel, a theoretical calculation model is established using the core physics calculation and analysis software. The established theoretical calculation model was checked and verified using typical critical rod positions in the reactor core obtained through actual reactor measurements. Based on the actual critical rod position status of the reactor, adjust the positions of the safety rods and other control rods in the theoretical calculation model after verification and validation, so that the position status of all control rods in the theoretical calculation model is consistent with the measured position status of the reactor rods. After the rod positions are adjusted to be consistent, initial parameters are set and parallel calculations are performed to obtain the normalized calculated value of neutron flux at the position of the activated plate and the normalized calculated value of neutron flux at the position of the neutron detector. The calculation deviation is controlled within a preset range. The ratio between the normalized calculated neutron flux at the location of the activated plate and the normalized calculated neutron flux at the location of the neutron detector is obtained.

2. The reactor neutron detector calibration method according to claim 1, characterized in that, The theoretical calculation model is established in the order from inside to outside and from small to large, and the fuel grid element, fuel assembly, core, core shroud, reflector and reactor vessel are described in detail in sequence. The activated sheet and neutron detector are modeled in detail according to their actual size and spatial position.

3. A reactor neutron detector calibration method according to any one of claims 1-2, characterized in that, The method of measuring the absolute value of neutron flux at the location of the activated plate using the activation method, and obtaining the absolute value of neutron flux at the location of the neutron detector according to the aforementioned proportional relationship, specifically includes: After the activated sheet is irradiated in the reactor core, the absolute value of the neutron flux at the location of the activated sheet is measured using a gamma spectrometer and an absolute neutron flux measurement system. Based on the reactor core power distribution characteristics and the synchronous fluctuation characteristics under the same core conditions, the following relationship is obtained: the ratio of the normalized calculated value of neutron flux at the activated plate location to the normalized calculated value of neutron flux at the neutron detector location is equal to the ratio of the absolute value of neutron flux at the activated plate location to the absolute value of neutron flux at the neutron detector location. The absolute value of the neutron flux at the location of the neutron detector is obtained based on the absolute value of the neutron flux at the location of the activated plate and the aforementioned proportional relationship.

4. The reactor neutron detector calibration method according to claim 3, characterized in that, For neutron detectors of the neutron counting tube type, the measurement result of the neutron detector is the number of counts.

5. The reactor neutron detector calibration method according to claim 3, characterized in that, For ionization chamber type neutron detectors, the neutron detector measures current values.

6. A reactor neutron detector calibration system, characterized in that, The calibration system includes: The model calculation module uses core physics calculation and analysis software to calculate the ratio between the normalized neutron flux at the activated sheet location and the normalized neutron flux at the neutron detector location. The measurement and calculation module uses the activation method to measure the absolute value of the neutron flux at the location of the activation plate, and obtains the absolute value of the neutron flux at the location of the neutron detector according to the proportional relationship. And, a conversion module, which calibrates the neutron detector conversion factor based on the neutron detector measurement results and the absolute value of the neutron flux at the neutron detector location; Wherein, the neutron detector conversion factor is the ratio of the neutron detector measurement result to the absolute value of the neutron flux at the neutron detector location; the model calculation module further includes: The model building unit establishes a theoretical calculation model using the reactor core physics calculation and analysis software based on the specific arrangement and material composition of the reactor core components, activation plates, neutron detectors, and reactor vessels. The verification unit uses typical critical rod positions of the reactor core obtained through actual reactor measurements to check and verify the established theoretical calculation model. The adjustment unit adjusts the positions of the safety rods and other control rods of the theoretical calculation model after verification and validation, according to the actual critical rod position state of the reactor, so that the position state of all control rods in the theoretical calculation model is consistent with the measured rod position state of the reactor. In addition, there is an iterative calculation unit, which sets initial parameters, performs parallel calculations, and obtains the normalized calculated value of neutron flux at the activation plate position and the normalized calculated value of neutron flux at the neutron detector position, thereby obtaining the proportional relationship between the normalized calculated value of neutron flux at the activation plate position and the normalized calculated value of neutron flux at the neutron detector position.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-5.

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