A method, device and equipment for replacing a self-powered neutron detector assembly

Abstract

The present invention discloses a method, device and equipment for replacing a self-powered neutron detector assembly. The method is based on the difference in neutron injection rate levels at different positions of the reactor core, and uses the burnup life and service life of the reactor core self-powered neutron detector assembly as service performance evaluation indicators to analyze the service performance of the self-powered neutron detector assembly; and combines the historical operating condition information of each energized neutron detector assembly, uses an intelligent prediction algorithm to evaluate whether the self-powered neutron detector assembly meets the requirements of neutron measurement in the next fuel cycle, and combines actual engineering needs to evaluate whether the detector assembly can extend its service life. The present invention can reduce the frequent replacement of core detector assemblies and improve the economy of nuclear power plants.

Description

Technical Field

[0001] The present invention relates to a reactor neutron detector design and analysis technology, and in particular to a method, device and equipment for replacing a self-powered neutron detector assembly. Background Art

[0002] During nuclear power plant reactor operation, self-powered neutron detectors are deployed at various locations within the core to measure the neutron flux density within the reactor. This allows them to monitor the power density distribution at various locations within the core, providing data for reactor safety control. These devices are crucial for ensuring safe and stable reactor operation. During operation within the reactor, self-powered neutron detectors are exposed to high temperatures and intense radiation for extended periods. This causes the detectors to gradually deplete and their material properties to change. Therefore, they must be replaced after a period of use to ensure proper function.

[0003] The current strategy for replacing in-core detectors primarily involves replacing all in-core detector assemblies during nuclear power plant refueling. However, during reactor operation, due to the uneven distribution of core power levels, detectors at different locations experience varying irradiation levels and operating conditions. This results in varying burnup lives of different in-core detector assemblies during actual operation. When some detector assemblies reach the end of their lifespan, the remaining service life of others can still support the next fuel cycle. Therefore, the current strategy of replacing all in-core detector assemblies fails to fully utilize the value of all assemblies, resulting in some components being wasted and increasing the cost of monitoring the operating status of nuclear power plant reactors. Summary of the Invention

[0004] The present invention aims to reduce the frequent replacement of core detector assemblies and improve the economy of nuclear power plants. The present invention aims to provide a method, device and equipment for replacing self-powered neutron detector assemblies. By analyzing the neutron measurement performance indicators and mechanical performance indicators of the detector assemblies, the relationship between the service performance and service life of the detector assemblies is established, and whether the detector assemblies meet the neutron measurement requirements of longer service lives is evaluated, thereby specifically extending the service lives of some detector assemblies and reducing the replacement and maintenance costs of the core detector assemblies of nuclear power plants.

[0005] The design idea of ​​the present invention is: to determine the burnup distribution of each detector component based on the historical operating data of the reactor, and to study the remaining burnup life of the detector component under different service periods through Monte Carlo modeling; to establish the relationship between the remaining service life of the detector component and the service period by studying the changes in the insulation performance of the detector insulation material and the mechanical properties and structural integrity of the detector component shell material with the service period of the core environment; finally, based on the remaining burnup life and the remaining service life, the evolution of the service performance of the detector component in the future service cycle is predicted based on the intelligent prediction algorithm, and each detector component is evaluated whether it meets the requirements for extending the service period. If it does not meet the requirements, the detector component will be replaced; otherwise, it will not be replaced.

[0006] The present invention is achieved through the following technical solutions:

[0007] In its first aspect, the present invention provides a method for replacing self-powered neutron detector assemblies. This method, based on the significant differences in neutron fluence levels at different locations in the reactor core, analyzes the service performance of the self-powered neutron detector assemblies using their burnup life and service life as service performance evaluation indicators. Furthermore, based on historical operating condition information such as the core neutron fluence rate and coolant temperature at the specific locations of each energized neutron detector assembly, an intelligent prediction algorithm is used to assess whether the self-powered neutron detector assembly meets the neutron measurement requirements for the next fuel cycle. Furthermore, the method assesses whether the detector assembly can be extended based on actual engineering needs, thereby extending the service life of some self-powered neutron detector assemblies.

[0008] Specifically, the method includes:

[0009] Based on the historical operating data of the reactor core self-powered neutron detector assembly, the burnup distribution of the self-powered neutron detector assembly is determined. Based on the burnup distribution of the self-powered neutron detector assembly, the relationship between the detector burnup life and service life is established through Monte Carlo simulation modeling. The remaining burnup life of the self-powered neutron detector assembly under different service life is analyzed.

[0010] By studying the changes in the insulation properties of the detector insulation material and the mechanical properties and structural integrity of the self-powered neutron detector assembly shell material with the service life of the core environment, the relationship between the service life of the self-powered neutron detector assembly and the service life is established, and the remaining service life of the self-powered neutron detector assembly under different service lives is analyzed.

[0011] According to the remaining burnup life and remaining service life, the service performance evolution of the self-powered neutron detector components in the future service cycle is predicted based on the intelligent prediction algorithm, and whether each self-powered neutron detector component meets the requirements for extending the service life is evaluated. If so, the self-powered neutron detector component will not be replaced; if not, the self-powered neutron detector component will be replaced.

[0012] Furthermore, based on the burnup distribution of each powered neutron detector assembly, a Monte Carlo simulation model was used to establish the relationship between the detector burnup life and service life. The remaining burnup life of the self-powered neutron detector assembly under different service lives was analyzed and obtained, including:

[0013] Obtaining the burnup depth of each energized neutron detector assembly according to the burnup distribution of each energized neutron detector assembly;

[0014] Based on the burnup depth of each powered neutron detector assembly, a Monte Carlo simulation tool was used to accurately simulate and establish a physical model for the self-powered neutron detector. The physical model couples the combined effects of particle transport and space charge to obtain information on the detector's neutron sensitivity under different burnup conditions.

[0015] Based on the neutron sensitivity information, the relationship between the detector burnup life and service life is established;

[0016] Based on the relationship between the detector burnup life and service life, the remaining burnup life of the self-powered neutron detector assembly under different service periods is obtained.

[0017] Furthermore, the service life of the self-powered neutron detector assembly at different service periods includes the remaining service life of the insulation material of the self-powered neutron detector assembly and the remaining service life of the housing material of the self-powered neutron detector assembly;

[0018] The remaining service life of the insulation material of the self-powered neutron detector assembly is obtained by accelerating the material damage rate by heavy ion irradiation, analyzing the insulation performance of the self-powered neutron detector insulation material, and establishing a relationship between the insulation performance of the detector insulation material and the service life.

[0019] The service life of the self-powered neutron detector component shell material is obtained by using heavy ion irradiation to accelerate the material irradiation damage rate, analyzing the mechanical properties of the self-powered neutron detector component shell material after irradiation, and establishing the relationship between the mechanical properties of the detector component shell material after irradiation and the service life.

[0020] Furthermore, the burnup life characterizes the degradation of neutron measurement performance of the self-powered neutron detector as the burnup deepens;

[0021] The service life characterizes the decline in the performance of the insulation material of the self-powered neutron detector over the service life, as well as the degradation of the mechanical properties of the shell material of the self-powered neutron detector component over the service life, which eventually leads to the failure of the detector component.

[0022] Furthermore, the historical operating condition information includes the core neutron flux rate, coolant temperature, etc. at a specific location.

[0023] Furthermore, based on the remaining burnup life and remaining service life, the intelligent prediction algorithm is used to predict the service performance evolution of the self-powered neutron detector components in the future service cycle, and to evaluate whether the individual self-powered neutron detector components meet the requirements for extending the service life, including:

[0024] According to the remaining burnup life and the remaining service life, the shortest of the two is selected as the maximum service life of the self-powered neutron detector assembly;

[0025] According to the maximum service life, the service performance evolution of the self-powered neutron detector components in the future service cycle is predicted based on the intelligent prediction algorithm, and combined with the historical operation information of the core, it is evaluated whether the self-powered neutron detector components need to be replaced in the next refueling cycle.

[0026] In a second aspect, the present invention further provides a device for replacing a self-powered neutron detector assembly, the device using the above-mentioned method for replacing a self-powered neutron detector assembly; the device comprising:

[0027] The remaining burnup life analysis unit is used to determine the burnup distribution of each powered neutron detector assembly based on the historical operating data of the reactor core self-powered neutron detector assembly. Based on the burnup distribution of each powered neutron detector assembly, the relationship between the detector burnup life and the service life is established through Monte Carlo simulation modeling, and the remaining burnup life of the self-powered neutron detector assembly under different service lives is analyzed and obtained;

[0028] The remaining service life analysis unit is used to establish the relationship between the service life of the self-powered neutron detector assembly and the service life by studying the changes in the insulation performance of the detector insulation material and the mechanical properties and structural integrity of the self-powered neutron detector assembly shell material with the service life of the core environment, and to analyze and obtain the remaining service life of the self-powered neutron detector assembly under different service lives;

[0029] The detector replacement judgment unit is used to predict the service performance evolution of the self-powered neutron detector components in the future service cycle based on the remaining burnup life and the remaining service life and the intelligent prediction algorithm, and evaluate whether each self-powered neutron detector component meets the requirements for extending the service life: if so, the self-powered neutron detector component will not be replaced; if not, the self-powered neutron detector component will be replaced.

[0030] Furthermore, the burnup life characterizes the degradation of neutron measurement performance of the self-powered neutron detector as the burnup deepens;

[0031] The service life characterizes the decline in the performance of the insulation material of the self-powered neutron detector over the service life, as well as the degradation of the mechanical properties of the shell material of the self-powered neutron detector component over the service life, which eventually leads to the failure of the detector component.

[0032] In a third aspect, the present invention further provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method for replacing a self-powered neutron detector assembly when executing the computer program.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] The present invention provides a method, device, and equipment for replacing self-powered neutron detector assemblies. This method, based on the significant differences in neutron fluence levels at different locations in the reactor core, analyzes the service performance of the self-powered neutron detector assemblies using their burnup life and service life as service performance evaluation indicators. Furthermore, combining historical operating condition information such as the core neutron fluence rate and coolant temperature at the specific locations of each energized neutron detector assembly, an intelligent prediction algorithm is used to assess whether the self-powered neutron detector assembly meets the neutron measurement requirements for the next fuel cycle. Furthermore, the method assesses whether the detector assembly can be extended in service based on actual engineering needs. This method thereby extends the service life of some self-powered neutron detector assemblies. The present invention can predict changes in the burnup life and service life of the detector assembly during the next future fuel cycle and assess whether the detector assembly can be extended in service based on actual engineering needs. This reduces the frequent replacement of core detector assemblies and improves the economic efficiency of nuclear power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0036] Figure 1 This is a flow chart of a method for replacing a self-powered neutron detector assembly according to the present invention;

[0037] Figure 2 This is a schematic structural diagram of the self-powered neutron detector assembly of the present invention;

[0038] Figure 3 The nanohardness of the 316L stainless steel after irradiation in the present invention corresponds to a service life of 48 months;

[0039] Figure 4 The hardness of the 316L stainless steel of the present invention changes with the service life;

[0040] Figure 5 The change of the surface resistance of the silicon dioxide of the present invention with the service life;

[0041] Figure 6 This is a structural block diagram of a replacement device for a self-powered neutron detector assembly according to the present invention. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0043] The current strategy for replacing in-core detectors primarily involves replacing all in-core detector assemblies during nuclear power plant refueling. However, during reactor operation, due to the uneven distribution of core power levels, detectors at different locations experience varying irradiation levels and operating conditions. This results in varying burnup lives of different in-core detector assemblies during actual operation. When some detector assemblies reach the end of their lifespan, the remaining service life of others can still support the next fuel cycle. Therefore, the current strategy of replacing all in-core detector assemblies fails to fully utilize the value of all assemblies, resulting in some components being wasted and increasing the cost of monitoring the operating status of nuclear power plant reactors.

[0044] Therefore, in view of the shortcomings of the current strategy for replacing the core detector assemblies of nuclear power plant reactors, in order to reduce the frequent replacement of the core detector assemblies and improve the economic efficiency of the nuclear power plant, the present invention designs a method, device and equipment for replacing the self-powered neutron detector assembly. The life of the core self-powered neutron detector assembly is mainly restricted by two factors: first, as the detector burns up and the insulation material performance deteriorates due to irradiation, the response of the detector to the neutron injection rate decreases, resulting in measurement failure of the detector; second, due to the core coolant flushing and the irradiation environment, the mechanical properties of the assembly shell decrease, resulting in an increased risk of fracture when the detector assembly is pulled out of the core again. The present invention analyzes the above two factors that affect the life of the detector assembly, that is, by analyzing the neutron measurement performance index and mechanical performance index of the detector assembly, establishing the relationship between the service performance of the detector assembly and the service life, evaluating whether the detector assembly meets the neutron measurement requirements of a longer service life, thereby specifically extending the service life of some detector assemblies and reducing the replacement and maintenance costs of the nuclear power plant core detector assembly.

[0045] For the first factor, the emitter burnup distribution is determined from historical current and accumulated charge data output by the detectors during service. The insulation performance of the detector insulation material is then determined by combining the radiation damage characteristics. Based on this information, the detector's neutron sensitivity (i.e., neutron measurement performance) is calculated through numerical simulation. For the second factor, the mechanical performance indicators of the detector components at each operational stage are determined based on the core operating environment. Then, based on the analyzed neutron sensitivity indicators (i.e., neutron measurement performance) and component mechanical performance indicators (i.e., mechanical performance indicators) for each operational stage, combined with the specific operating conditions of the detector's location within the core, a health management approach is used to analyze the changes in these indicators during the next fuel cycle and assess whether the detector components meet technical requirements at the end of the next fuel cycle. For detector components that have already served for several refueling cycles, the aforementioned method is used to analyze the changes in each performance indicator at each location at the end of reactor operation, based on the operating conditions of the specific core location during the next refueling cycle. Components that meet the requirements and can continue to operate for another refueling cycle do not need to be replaced, thereby reducing the consumption of core detector components and improving the economic efficiency of the nuclear power plant.

[0046] During the operation of a nuclear power plant's pressurized water reactor, the neutron injection rate levels at different locations in the core vary by more than two times, resulting in different degrees of degradation in the performance of detector assemblies at different locations in the core. This is the basis for extending the service life of detector assemblies. The design concept of this invention is as follows: based on the historical operating data of the reactor, the burnup distribution of each detector assembly is determined, and the remaining burnup life of the detector assembly under different service periods is studied through Monte Carlo modeling; by studying the changes in the insulation performance of the detector insulation material and the mechanical properties and structural integrity of the detector assembly shell material with the service life of the core environment, the relationship between the remaining service life of the detector assembly and the service period is established; finally, based on the intelligent prediction algorithm, the evolution of the service performance of the detector assembly in the future service cycle is predicted, and whether each detector assembly meets the requirements for extending the service period is evaluated.

[0047] Example 1

[0048] like Figure 1As shown, the present invention provides a method for replacing self-powered neutron detector assemblies. This method, based on the significant differences in neutron fluence levels at different locations in the reactor core, uses the burnup life and service life of the reactor core self-powered neutron detector assemblies as service performance evaluation indicators to analyze their service performance. Furthermore, based on historical operating condition information such as the core neutron fluence rate and coolant temperature at the specific locations of each energized neutron detector assembly, an intelligent prediction algorithm is used to assess whether the self-powered neutron detector assembly meets the neutron measurement requirements for the next fuel cycle. Furthermore, based on actual engineering requirements, the detector assembly's service life can be extended. This method can thereby extend the service life of some self-powered neutron detector assemblies.

[0049] Among them, the burnup life represents the decline in neutron measurement performance of the self-powered neutron detector as the burnup deepens; the service life represents the decline in the performance of the insulation material of the self-powered neutron detector as the service life increases, as well as the degradation of the mechanical properties of the shell material of the self-powered neutron detector component as the service life increases, which eventually leads to the failure of the detector component.

[0050] Specifically, the method includes:

[0051] Step 1: Based on the historical operating data of the reactor core self-powered neutron detector assembly, the burnup distribution of each powered neutron detector assembly is determined; based on the burnup distribution of each powered neutron detector assembly, a relationship between the detector burnup life and the service life is established through Monte Carlo simulation modeling, and the remaining burnup life of the self-powered neutron detector assembly under different service lives is analyzed and obtained;

[0052] In this embodiment, in step 1, the burnup distribution of each powered neutron detector assembly is determined based on the historical operating data of the reactor core self-powered neutron detector assembly, specifically:

[0053] The self-powered neutron detector assembly of the present invention serves in the reactor core for a certain period T. The nuclear power plant core measurement system can continuously collect and record the current data output by each energized neutron detector during the period t, thereby deriving the burnup information of the detector after the service period T. At this time, the atomic nuclei density of the neutron sensitive body at different depths of the self-powered neutron detector emitter is: N(T):

[0054]

[0055] Where N0 is the initial atomic nucleus density of the emitter sensitive material, V is the emitter volume, I(t) is the detector output current at time t, and e is the electron charge 1.6×10 -19 C.

[0056] In step 1, based on the burnup distribution of each powered neutron detector assembly, a Monte Carlo simulation model is used to establish the relationship between the detector burnup life and service life. The remaining burnup life of the self-powered neutron detector assembly under different service lives is analyzed and obtained. Specifically,

[0057] The present invention simulates and models the self-powered neutron detector through the Monte Carlo program. The detector material and geometric structure parameters are consistent with the actual situation. The neutron-sensitive material parameters of the detector emitter are provided by the above. The irradiation environment is the real neutron-photon irradiation field of the pressurized water reactor core. The particle transport process occurring in the detector is simulated to obtain the neutron sensitivity of the self-powered neutron detector under a specific service life, thereby realizing the burnup life assessment of the detector component.

[0058] Step 2: By studying the changes in the insulation properties of the detector insulation material and the mechanical properties and structural integrity of the self-powered neutron detector assembly shell material over the service life of the core environment, the relationship between the service life of the self-powered neutron detector assembly and the service life is established, and the remaining service life of the self-powered neutron detector assembly under different service lives is analyzed;

[0059] In this embodiment, the service life of the self-powered neutron detector assembly at different service periods includes the remaining service life of the insulation material of the self-powered neutron detector assembly and the remaining service life of the housing material of the self-powered neutron detector assembly;

[0060] The remaining useful life of the insulation material of the self-powered neutron detector assembly is determined by analyzing the insulation performance of the self-powered neutron detector insulation material using heavy ion irradiation to accelerate the material's irradiation damage rate. This involves evaluating how the insulation performance of the self-powered neutron detector assembly insulation material changes with the degree of irradiation damage (corresponding to a specific service life) and establishing a relationship between the insulation performance of the detector insulation material and its service life.

[0061] The service life of the self-powered neutron detector component shell material is obtained by using heavy ion irradiation to accelerate the material irradiation damage rate, and conducting a mechanical property analysis of the self-powered neutron detector component shell material after irradiation. That is, evaluating the change of the mechanical performance indicators of the detector component shell material with its irradiation damage degree (corresponding to a specific service life), and establishing the relationship between the mechanical properties of the detector component shell material after irradiation and the service life.

[0062] Step 3: Based on the remaining burnup life and remaining service life, the service performance evolution of the self-powered neutron detector components in the future service cycle is predicted based on the intelligent prediction algorithm, and whether each self-powered neutron detector component meets the requirements for extending the service life is evaluated: if it meets the requirements, the self-powered neutron detector component will not be replaced; if it does not meet the requirements, the self-powered neutron detector component will be replaced.

[0063] Specifically, based on the remaining burnup life and remaining service life, the intelligent prediction algorithm is used to predict the service performance evolution of the self-powered neutron detector components in the future service cycle, and to evaluate whether the individual self-powered neutron detector components meet the requirements for extending the service life, including:

[0064] According to the remaining burnup life and the remaining service life, the shortest of the two is selected as the maximum service life of the self-powered neutron detector assembly;

[0065] According to the maximum service life, the service performance evolution of the self-powered neutron detector components in the future service cycle is predicted based on the intelligent prediction algorithm, and combined with the historical operation information of the core, it is evaluated whether the self-powered neutron detector components need to be replaced in the next refueling cycle.

[0066] In this embodiment, the life extension service plan of the self-sufficient neutron detector assembly of the present invention is based on the residual burnup life and remaining service life obtained from the evolution law of the burnup life and service life of the detector assembly with the service period analyzed in steps 1 and 2; intelligent prediction algorithms such as neural networks, support vector machines, and correlation vector machines are introduced, and the above data are used as sample input data of the intelligent prediction model to complete model training, so as to predict the changes in the burnup life and service life of the detector assembly in the next fuel cycle in the future, and evaluate whether the detector assembly can be extended in service in combination with actual engineering needs.

[0067] The specific implementation is as follows:

[0068] This embodiment of the self-powered neutron detector assembly replacement method takes the rhodium-103 self-powered neutron detector as an example, the emitter diameter is 0.5mm, the density is 12.38g / cm 3 The insulating layer is made of silicon dioxide with a thickness of 0.25mm, and the collector is made of stainless steel with a thickness of 0.2mm. The housing is made of 316L stainless steel with an outer diameter of 10mm and a thickness of 1mm. The self-powered detector is 250mm long and is located in the center of the component casing. The entire detector structure is as follows Figure 2 shown.

[0069] The specific analysis steps are as follows:

[0070] (1) During the full power operation of a certain pressurized water reactor, the average neutron injection rate level in the core is 5×10 13 n·cm -2 ·s -1 The initial atomic density of the self-powered neutron detector emitter material rhodium-103 is 0.718×10 23 / cm 3, at this time the detector output current intensity is about microampere level. The detector current intensity collected per second during the operation of the reactor is I(t). According to formula (1), the residual nucleus density of rhodium-103 after 18 months of service (one refueling cycle) can be calculated to be 0.529×10 23 / cm 3 After 36 months of service (two refueling cycles), the residual nucleus density of rhodium-103 is 0.387×10 23 / cm 3 It can be seen that after two refueling cycles, the atomic density of rhodium-103, the emitter material of the self-powered neutron detector, is approximately 59% of the initial atomic density. Assuming that the operating conditions of the reactor in the third refueling cycle are basically the same as those in the first two refueling cycles, the RVM model can be extrapolated to obtain a density of approximately 0.281×10 23 / cm 3 The calculation steps for the atomic density of rhodium-103, the emitter material of the self-sustaining neutron detector after 54 months of service are as follows:

[0071] A, suppose the input and output data of a problem are and And the target data It can be expressed as the relevant vector machine model shown in formula (2):

[0072]

[0073] Among them, x is the corresponding service life, y is the corresponding rhodium-103 atomic density, ε n represents noise with mean 0 and variance σ2, K(x,x i ) is the kernel function, w i is the weight vector and w0 is the bias.

[0074] B, based on historical sample data and Training the related vector machine model, the model uses Gaussian radial basis function, the parameters in the model (ε n 、w i , kernel function parameters) are implemented through quantum particle swarm filtering algorithm to determine the model parameters in formula (2).

[0075] C. Based on the completion of the correlation vector machine model training, the rhodium-103 atomic density corresponding to the unknown service life (54 months) can be deduced.

[0076] (2) The self-powered neutron detector was simulated and modeled using the Monte Carlo program GEANT4. The detector material and geometric structure parameters were as follows: Figure 2As shown, the atomic density of the detector emitter material rhodium-103 is set to 0.281×10 23 / cm 3 . The irradiation environment is a real neutron-photon irradiation field of a pressurized water reactor core. Through simulation calculation, it is found that the current signal intensity output by the self-sufficient neutron detector under the condition of a service life of 54 months is 1.43 microamperes. Generally, the lower limit of the current signal that can be processed by the signal processing equipment of the reactor core self-sufficient neutron detector is on the order of 0.1 nanoamperes. Therefore, for the 1.43 microampere current signal output by the self-sufficient neutron detector that has been in service for 54 months, the signal processing equipment can effectively process and collect it, that is, the core measurement system can realize effective monitoring of the core power. In summary, for the described detector and reactor operating conditions, the burnup life of the detector meets the service requirement of 54 months.

[0077] (3) Using the Monte Carlo (MCNP) modeling tool, we analyzed the radiation damage levels (DPA values) of 316L stainless steel subjected to a realistic neutron-photon irradiation field in the core for 1, 2, 3, 4, 47, and 48 months. Based on this, we designed the heavy ion beam parameters for different service periods. Iron ions with an energy of 4 MeV were selected as the irradiation source.

[0078] (4) The relationship between the continuous change of material hardness and indentation depth in the depth range of 0 to 2000 nm was measured by nanoindentation instrument. The actual hardness distribution of the irradiated sample was obtained through processing. A total of 48 sets of hardness data were obtained, corresponding to each service life. Figure 3 The figure shows the hardness distribution of the sample after 48 months of service. The hardness of the sample after irradiation is 5.5 GPa. Figure 4 The figure shows the change in hardness of 316L corresponding to a service period of 1 month to 48 months, which is used as sample data to predict the change in material hardness during subsequent service periods.

[0079] (5) Based on the RVM model, as shown in step (1), 48 sets of hardness data are input into the RVM model. After model training, the hardness change of 316L stainless steel from 49 months to 54 months can be output, as shown in Figure 2. Figure 4 shown.

[0080] (6) From Figure 4 It can be seen that the hardness of 316L stainless steel after 54 months of service is 5.8GPa. Combined with the hardness of the original non-irradiated sample of 3.3GPa and the yield strength of 248MPs, according to the increase in the yield strength of the material induced by irradiation (Δσ y ) and the increase in nanohardness (ΔH) y= 0.306ΔH, indicating that the actual yield strength of the irradiated 316L stainless steel sample is 1013 MPa. Assuming the yield strength ratio of the irradiated stainless steel sample is 1, the tensile strength of the irradiated stainless steel sample is 1013 MPa. Based on the specific structure of the self-powered neutron detector assembly housing, the tensile strength limit of the housing material can be calculated to be approximately 6000 N. Combined with the design requirements of the self-powered neutron detector assembly, it can be determined whether the detector assembly meets the 54-month service life requirement.

[0081] (7) The silicon dioxide insulating material used in the detector is irradiated according to the method shown in step (3), and oxygen ions with an energy of 5 MeV are selected as the irradiation source.

[0082] (8) After oxygen particle irradiation, the surface resistance of the SiO2 insulating material sample was measured by the four-probe method, and a total of 48 sets of surface resistance data samples were obtained, such as Figure 5 shown.

[0083] (9) Based on the RVM model, as shown in step (1), 48 sets of surface resistance data are input into the RVM model. After model training, the change of silicon dioxide surface resistance from 49 months to 54 months can be output, as shown in FIG. Figure 5 shown.

[0084] (10) From Figure 5 It can be seen that the surface resistance of silicon dioxide after 54 months of service is 1.00×10 12 Ω·m, compared with the initial surface resistance of unirradiated silicon dioxide of 9.12×10 12 Compared with Ω·m, it has decreased by about one order of magnitude. Combined with the insulation performance design requirements of self-powered neutron detectors, it can be determined whether the silica insulation material meets the 54-month service requirement.

[0085] The above has achieved the evaluation of extending the service life of the self-powered neutron detector assembly, and based on this, a more economical detector assembly replacement plan has been realized.

[0086] For a longer service life, repeat steps (1) to (10) to determine the burnup life of the self-powered neutron detector assembly and the corresponding service life of the assembly shell material and the self-powered neutron detector insulation material, and use the shortest life span as the maximum service life of the detector assembly.

[0087] The method of the present invention establishes the relationship between the burnup life and service life of the self-powered neutron detector assembly and the service life by analyzing the output current signal quality, the insulation performance of the detector insulation material, and the mechanical properties of the detector assembly shell material of the self-powered neutron detector assembly at different service life lengths at specific core locations. It also judges whether the detector assembly meets the neutron monitoring requirements and safety requirements of the next fuel cycle in combination with the core historical operation data, providing data support for the replacement of the detector assembly. The basis for the implementation of this method is that there are large differences in the neutron injection rate levels at different locations in the core during the operation of the reactor, resulting in different degrees of performance degradation of the detector assemblies arranged at different locations in the core. The current solution of replacing all detector assemblies in a batch will result in the waste of some detector assemblies that still have relatively long remaining service performance. Therefore, the service performance analysis of the burnup life, service life, etc. is carried out separately for each detector assembly, and the detector assemblies with relatively long remaining service performance are identified and their service life is extended. This can reduce the number of core detector assembly replacements during the nuclear power plant shutdown and refueling period, and reduce the operation and maintenance costs of the nuclear power plant.

[0088] Example 2

[0089] like Figure 6 As shown, the difference between this embodiment and embodiment 1 is that this embodiment provides a self-powered neutron detector assembly replacement device, which uses a self-powered neutron detector assembly replacement method of embodiment 1; the device includes:

[0090] The remaining burnup life analysis unit is used to determine the burnup distribution of each powered neutron detector assembly based on the historical operating data of the reactor core self-powered neutron detector assembly. Based on the burnup distribution of each powered neutron detector assembly, the relationship between the detector burnup life and the service life is established through Monte Carlo simulation modeling, and the remaining burnup life of the self-powered neutron detector assembly under different service lives is analyzed and obtained;

[0091] The remaining service life analysis unit is used to establish the relationship between the service life of the self-powered neutron detector assembly and the service life by studying the changes in the insulation performance of the detector insulation material and the mechanical properties and structural integrity of the self-powered neutron detector assembly shell material with the service life of the core environment, and to analyze and obtain the remaining service life of the self-powered neutron detector assembly under different service lives;

[0092] The detector replacement judgment unit is used to predict the service performance evolution of the self-powered neutron detector components in the future service cycle based on the remaining burnup life and the remaining service life and the intelligent prediction algorithm, and evaluate whether each self-powered neutron detector component meets the requirements for extending the service life: if so, the self-powered neutron detector component will not be replaced; if not, the self-powered neutron detector component will be replaced.

[0093] Specifically, the burnup lifetime characterizes the degradation of neutron measurement performance of a self-powered neutron detector as the burnup deepens;

[0094] The service life characterizes the decline in the performance of the insulation material of the self-powered neutron detector over the service life, as well as the degradation of the mechanical properties of the shell material of the self-powered neutron detector component over the service life, which eventually leads to the failure of the detector component.

[0095] The execution process of each unit can be performed according to the process steps of the method for replacing a self-powered neutron detector assembly in Example 1, and will not be described in detail in this embodiment.

[0096] At the same time, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the computer program, a method for replacing a self-powered neutron detector assembly of Example 1 is implemented.

[0097] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0098] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0099] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0100] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0101] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for replacing a self-powered neutron detector assembly, characterized in that: This method is based on the difference in neutron injection rate levels at different positions in the reactor core. The burnup life and service life of the reactor core self-powered neutron detector assembly are used as service performance evaluation indicators to analyze the service performance of the self-powered neutron detector assembly. In combination with the historical operating condition information of each self-powered neutron detector assembly, an intelligent prediction algorithm is used to evaluate whether the self-powered neutron detector assembly meets the requirements of neutron measurement in the next fuel cycle, and whether the detector assembly can be extended in service in combination with actual engineering needs. The method includes: Based on the historical operation data of the reactor core self-powered neutron detector assembly, the burnup distribution of the self-powered neutron detector assembly is determined; according to the burnup distribution of the self-powered neutron detector assembly, the relationship between the detector burnup life and the service life is established through Monte Carlo simulation modeling, and the remaining burnup life of the self-powered neutron detector assembly under different service lives is analyzed; By studying the changes in the insulation properties of detector insulation materials and the mechanical properties and structural integrity of the shell materials of self-powered neutron detector components with the service life of the core environment, the relationship between the service life of self-powered neutron detector components and the service life is established, and the remaining service life of self-powered neutron detector components under different service lives is analyzed. According to the remaining burnup life and the remaining service life, the evolution of the service performance of the self-powered neutron detector assembly in the future service cycle is predicted based on the intelligent prediction algorithm, and whether each self-powered neutron detector assembly meets the requirements for extending the service life is evaluated: if so, the self-powered neutron detector assembly is not replaced; if not, the self-powered neutron detector assembly is replaced; Historical operating condition information includes core neutron injection rate and coolant temperature at specific locations; According to the remaining burnup life and the remaining service life, the evolution of the service performance of the self-powered neutron detector assembly in the future service period is predicted based on the intelligent prediction algorithm, and whether the self-powered neutron detector assembly meets the requirements for extending the service period is evaluated, including: According to the remaining burnup life and the remaining service life, selecting the shortest life span between the two as the maximum service life of the self-powered neutron detector assembly; According to the said maximum service life, the service performance evolution of the self-powered neutron detector assembly in the future service cycle is predicted based on the intelligent prediction algorithm, and combined with the historical operation information of the core, it is evaluated whether the self-powered neutron detector assembly needs to be replaced in the next refueling cycle.

2. A method for replacing a self-powered neutron detector assembly according to claim 1, characterized in that: According to the burnup distribution of the self-powered neutron detector components, the relationship between the detector burnup life and service life is established through Monte Carlo simulation modeling, and the remaining burnup life of the self-powered neutron detector components under different service periods is analyzed, including: Obtaining the burnup depth of each energized neutron detector assembly according to the burnup distribution of each energized neutron detector assembly; According to the burnup depth of each powered neutron detector assembly, a physical model is established by accurately simulating the self-powered neutron detector through Monte Carlo tools; the physical model couples the comprehensive effects of particle transport and space charge, thereby obtaining the neutron sensitivity information of the detector under different burnup conditions; Establishing a relationship between the detector burnup life and service life based on the neutron sensitivity information; The remaining burnup life of the self-powered neutron detector assembly at different service periods is obtained based on the relationship between the burnup life of the detector and the service period.

3. A method for replacing a self-powered neutron detector assembly according to claim 1, characterized in that: The service life of the self-powered neutron detector assembly at different service periods includes the remaining service life of the insulating material of the self-powered neutron detector assembly and the remaining service life of the shell material of the self-powered neutron detector assembly; The remaining service life of the insulating material of the self-powered neutron detector assembly is obtained by: using heavy ion irradiation to accelerate the material irradiation damage rate, performing an insulation performance analysis on the insulating material of the self-powered neutron detector, and establishing a relationship between the insulation performance of the detector insulating material and the service life; The service life of the shell material of the self-powered neutron detector assembly is obtained by accelerating the irradiation damage rate of the material by heavy ion irradiation, analyzing the mechanical properties of the shell material of the self-powered neutron detector assembly after irradiation, and establishing the relationship between the mechanical properties of the shell material of the detector assembly after irradiation and the service life.

4. The method for replacing a self-powered neutron detector assembly according to claim 1, characterized in that: The burnup life represents the degradation of neutron measurement performance of the self-powered neutron detector as the burnup increases; The service life characterizes the decline in the performance of the insulating material of the self-powered neutron detector with the service life and the degradation of the mechanical properties of the shell material of the self-powered neutron detector component with the service life, which eventually leads to the failure of the detector component.

5. A replacement device for a self-powered neutron detector assembly, characterized in that: The device includes: The remaining burnup life analysis unit is used to determine the burnup distribution of the respective powered neutron detector components based on the historical operation data of the reactor core self-powered neutron detector components; according to the burnup distribution of the respective powered neutron detector components, the relationship between the detector burnup life and the service life is established through Monte Carlo simulation modeling, and the remaining burnup life of the self-powered neutron detector components under different service lives is analyzed and obtained; The remaining service life analysis unit is used to establish the relationship between the service life of the self-powered neutron detector assembly and the service life by studying the changes in the insulation performance of the detector insulation material and the mechanical properties and structural integrity of the shell material of the self-powered neutron detector assembly with the service life of the core environment, and to analyze and obtain the remaining service life of the self-powered neutron detector assembly under different service lives; A detector replacement judgment unit is used to predict the evolution of the service performance of the self-powered neutron detector assembly in the future service cycle based on the remaining burnup life and the remaining service life and based on the intelligent prediction algorithm, and evaluate whether each neutron detector assembly meets the requirements for extending the service life: if so, the self-powered neutron detector assembly is not replaced; if not, the self-powered neutron detector assembly is replaced; According to the remaining burnup life and the remaining service life, the evolution of the service performance of the self-powered neutron detector assembly in the future service period is predicted based on the intelligent prediction algorithm, and whether the self-powered neutron detector assembly meets the requirements for extending the service period is evaluated, including: According to the remaining burnup life and the remaining service life, selecting the shortest life span between the two as the maximum service life of the self-powered neutron detector assembly; According to the said maximum service life, the service performance evolution of the self-powered neutron detector assembly in the future service cycle is predicted based on the intelligent prediction algorithm, and combined with the historical operation information of the core, it is evaluated whether the self-powered neutron detector assembly needs to be replaced in the next refueling cycle.

6. A replacement device for a self-powered neutron detector assembly according to claim 5, characterized in that: The burnup life represents the degradation of neutron measurement performance of the self-powered neutron detector as the burnup increases; The service life characterizes the decline in the performance of the insulating material of the self-powered neutron detector with the service life and the degradation of the mechanical properties of the shell material of the self-powered neutron detector component with the service life, which eventually leads to the failure of the detector component.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for replacing a self-powered neutron detector assembly as described in any one of claims 1 to 4 is implemented.

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