Method, device and computer equipment for determining the critical power of a fuel rod PCI

Abstract

The application discloses a fuel rod PCI critical power determination method, device and computer equipment. The method comprises the following steps: obtaining expected power of fuel rods in each operation stage in a life cycle in a nuclear reactor core; determining target power and target burnup of the fuel rods in a steady state according to the expected power; and determining PCI critical power of the fuel rods in the target power and target burnup operation state by performing transient change on the target power according to a restriction condition corresponding to a cladding type of the fuel rods. The application determines the PCI critical power of different fuel rods under different operation power and burnup, improves the reliability and comprehensiveness of the PCI performance analysis of the fuel rods, is beneficial to adjusting and controlling the actual operation of the fuel rods, and avoids PCI performance failure of the fuel rods.

Description

Technical Field

[0001] The present application relates to the field of nuclear reactor application technology, and in particular to a method, device, and computer equipment for determining the PCI critical power of a fuel rod. Background Art

[0002] Fuel rods are core components of nuclear reactors, and their structural integrity is crucial to the safe operation of the entire reactor. Fuel rods consist of cladding tubes, fuel pellets, air springs, and upper and lower end plugs. Initial designs leave a certain gap between the fuel pellets and the cladding tubes to accommodate deformation.

[0003] During nuclear reactor operation, fuel pellets are affected by radiation and thermal effects, undergoing outward radiation swelling and thermal expansion. The cladding, on the other hand, creeps inward under the combined effects of the coolant's external pressure and the fuel rod's internal pressure. In the middle and late stages of nuclear reactor operation, the combined effects of long-term outward radiation swelling and thermal expansion of the fuel pellets and inward creep of the cladding can reduce the gap between the fuel pellets and cladding to zero, leading to contact. This phenomenon is known as pellet-cladding interaction (PCI).

[0004] Under transient conditions during nuclear reactor operation, due to the rapid increase in nuclear reactor power, the fuel pellets will produce a greater thermal expansion effect than during normal operation, which will cause the cladding to produce greater stress and strain during the PCI process and exceed the failure limit, causing the cladding to fail and no longer have the ability to contain fission products, and affecting the operational safety of the nuclear reactor.

[0005] To prevent cladding failure, related technologies select fuel rods with typical or specific characteristics within each fuel assembly in the core. The PCI performance of these fuel rods is then analyzed based on the initial design data for these selected fuel rods. However, the PCI performance of unselected fuel rods in the core, as well as the power fluctuations associated with these fuel rods during actual operation, are not fully considered. Summary of the Invention

[0006] In view of this, the present application provides a method, device, and computer equipment for determining the PCI critical power of fuel rods. By using the constraints corresponding to the expected power of the fuel rods and the cladding type, the PCI critical power of the fuel rods when transients occur at different operating powers and burnups is determined, and the safety boundaries of different fuel rods under different operating conditions are accurately grasped, thereby enhancing the performance analysis effect and preventing PCI performance failure.

[0007] According to one aspect of the present application, a method for determining the PCI critical power of a fuel rod is provided, comprising: obtaining the expected power of a fuel rod in a nuclear reactor core at each operating stage during its life cycle; determining a target power and a target burnup of the fuel rod in a steady state based on the expected power; and performing a transient change to the target power based on the constraint conditions corresponding to the cladding type of the fuel rod to determine the PCI critical power of the fuel rod under operation at the target power and target burnup.

[0008] Optionally, performing a transient change on the target power according to the constraint corresponding to the cladding type of the fuel rod to determine the PCI critical power of the fuel rod under the target power and target burnup operation includes: determining a first power change amount and a second power change amount according to the magnitude of the target power; determining a first transient power according to the target power and the first power change amount; determining a second transient power according to the first transient power and the second power change amount; and respectively determining a first index value and a second index value of an influencing factor of the fuel rod under the first transient power and the second transient power operation; wherein, if the first index value is less than a critical index value corresponding to the constraint and the second index value is greater than the critical index value corresponding to the constraint, the first transient power corresponding to the first index value is used as the PCI critical power; and if the first index value is greater than or equal to the critical index value corresponding to the constraint, or the second index value is less than or equal to the critical index value corresponding to the constraint, adjusting the first power change amount so that the first index value re-determined according to the adjusted first transient power is less than the critical index value corresponding to the constraint and the second index value is greater than the critical index value corresponding to the constraint.

[0009] Optionally, if the first index value is greater than or equal to the critical index value corresponding to the restriction condition, or the second index value is less than or equal to the critical index value corresponding to the restriction condition, adjusting the first power change includes: if the first index value is greater than or equal to the critical index value corresponding to the restriction condition, reducing the first power change according to a preset power correction amount; if the second index value is less than or equal to the critical index value corresponding to the restriction condition, increasing the first power change according to the preset power correction amount.

[0010] Optionally, the influencing factors include at least one of the following: cladding strain, fuel temperature, cladding strain energy density and cladding TRESCA stress.

[0011] Optionally, the fuel rod PCI critical power determination method further includes: performing an offset process on the expected power of at least one of the operation stages according to a preset offset amount.

[0012] Optionally, determining the target power and target burnup of the fuel rod in a stable state based on the expected power includes: interpolating or fitting the expected power collected at sampling moments to determine the target power at the calculation moment; wherein the calculation moment between the sampling moments is determined based on a preset time interval; and the target burnup at the calculation moment is determined based on the target power at the calculation moment.

[0013] Optionally, before performing interpolation or fitting processing on the expected power collected at the sampling moments, the method further includes: processing the expected power at any of the sampling moments according to the structural parameters of the fuel rod to update the expected power.

[0014] Optionally, the method for determining the PCI critical power of the fuel rod also includes: determining the PCI critical power database of the nuclear reactor core based on the PCI critical power; obtaining the actual power and actual burn-up of the fuel rod at the monitoring moment; calling the target PCI critical power in the PCI critical power database that matches the actual power and actual burn-up of the fuel rod; if the difference between the actual power of the fuel rod and the target PCI critical power does not meet the preset threshold condition, generating an early warning message.

[0015] According to another aspect of the present application, a fuel rod PCI critical power determination device is provided, comprising: an acquisition module for acquiring the expected power of a fuel rod in a nuclear reactor core at various operating stages during its life cycle; a determination module for determining a target power and a target burnup of the fuel rod in a steady state based on the expected power; and, performing a transient change on the target power based on the constraint conditions corresponding to the cladding type of the fuel rod to determine the PCI critical power of the fuel rod under operation at the target power and target burnup.

[0016] Optionally, the determining module is specifically configured to: determine the PCI critical power of the fuel rod under the target power and target burnup operation according to transient changes of the target power based on the limit condition corresponding to the cladding type of the fuel rod, including: determining a first power change amount and a second power change amount according to a magnitude of the target power; determining a first transient power according to the target power and the first power change amount; determining a second transient power according to the first transient power and the second power change amount; respectively determining a first index value and a second index value of the influencing factor of the fuel rod under the first transient power and the second transient power; wherein, if the first index value is less than a critical index value corresponding to the limit condition, and the second index value is greater than the critical index value corresponding to the limit condition, the first transient power corresponding to the first index value is taken as the PCI critical power; if the first index value is greater than or equal to the critical index value corresponding to the limit condition, or the second index value is less than or equal to the critical index value corresponding to the limit condition, the first power change amount is adjusted so that the first index value re-determined according to the adjusted first transient power is less than the critical index value corresponding to the limit condition, and the second index value is greater than the critical index value corresponding to the limit condition.

[0017] Optionally, the determining module is specifically configured to: if the first index value is greater than or equal to the critical index value corresponding to the limit condition, or the second index value is less than or equal to the critical index value corresponding to the limit condition, the first power change amount is adjusted, including: if the first index value is greater than or equal to the critical index value corresponding to the limit condition, the first power change amount is reduced according to a preset power correction amount; and if the second index value is less than or equal to the critical index value corresponding to the limit condition, the first power change amount is increased according to the preset power correction amount.

[0018] Optionally, the influencing factor includes at least one of the following: cladding strain, fuel temperature, cladding strain energy density, and cladding TRESCA stress.

[0019] Optionally, the fuel rod PCI critical power determination device further includes:

[0020] The offset module is specifically configured to: offset the expected power of at least one of the operation stages according to a preset offset amount.

[0021] Optionally, the determining module is configured to: interpolate or fit the expected power collected at a sampling time to determine the target power at a calculation time; wherein the calculation time between the sampling times is determined according to a preset time interval; and the target burnup at the calculation time is determined according to the target power at the calculation time.

[0022] Optionally, the fuel rod PCI critical power determination device further includes:

[0023] The updating module is specifically configured to: before interpolating or fitting the expected power collected at the sampling moments, further process the expected power at any of the sampling moments according to the structural parameters of the fuel rod to update the expected power.

[0024] Optionally, the fuel rod PCI critical power determination device further includes:

[0025] The early warning module is specifically configured to: determine a PCI critical power database of the nuclear reactor core based on the PCI critical power; obtain the actual power and actual burnup of the fuel rod at the monitoring moment; call a target PCI critical power from the PCI critical power database that matches the actual power and actual burnup of the fuel rod; and generate an early warning message if the difference between the actual power of the fuel rod and the target PCI critical power does not meet a preset threshold condition.

[0026] According to another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the program, the steps of the above-mentioned method for determining the fuel rod PCI critical power are implemented.

[0027] By means of the above technical solution, the present application provides a method, apparatus, and computer device for determining the PCI critical power of a fuel rod. These methods determine the target power and target burnup that may exist during the actual operation of the fuel rod based on the expected power of the fuel rod, fully considering the power fluctuations during the actual operation of the fuel rod. Based on the constraints corresponding to the cladding type of the fuel rod, the PCI critical power of the fuel rod when a transient occurs under the target power and target burnup is determined. This accurately defines the safety limits of different fuel rods under different operating powers and burnups, improves the reliability and comprehensiveness of the fuel rod PCI performance analysis, facilitates the adjustment and control of the actual operation of the fuel rod, and avoids PCI performance failure of the fuel rod.

[0028] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 A schematic flow chart of a method for determining fuel rod PCI critical power according to an embodiment of the present application is shown;

[0031] Figure 2 The following is a structural block diagram of a fuel rod PCI critical power determination device provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of the design power history and virtual power history provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0033] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0034] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and are not to be construed as limiting the present application.

[0035] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of this application refers to the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, or there may be intermediate elements. In addition, "connected" or "connected" as used herein may include wireless connection or wireless fusion. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0036] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in a variety of different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of this application thorough and complete and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art.

[0037] The fuel rod PCI critical power determination method provided in the embodiments of the present application can be applied to a terminal or a server, or can be software running on the terminal or server. In some embodiments, the terminal can be a smartphone, tablet computer, laptop computer, desktop computer, etc.; the server can be configured as an independent physical server, or as a server cluster or distributed system composed of multiple physical servers, or as a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms; the software can be an application that implements the fuel rod PCI critical power determination method, etc., but is not limited to the above forms.

[0038] In this embodiment, a method for determining the fuel rod PCI critical power is provided, such as Figure 1 As shown, the method includes:

[0039] Step 101: Obtain the expected power of the fuel rods in the nuclear reactor core at each operating stage during their life cycle.

[0040] In this embodiment, the expected power of the fuel rods in the nuclear reactor core at each operating stage during their life cycle is obtained, providing a reasonable reference basis and calculation basis for the subsequent determination of the PCI critical power. This helps to understand the power requirements and changing trends of the fuel rods at different stages, thereby better evaluating their PCI performance under different operating conditions.

[0041] For example, Figure 3 As shown, considering the 1 / 8 symmetry of the nuclear reactor core, the design power history (expected power) of each fuel rod in any symmetrical 1 / 8 of the nuclear reactor core during each cycle (operation stage) of the life cycle is obtained.

[0042] It should be noted that the design power history is the change in fuel rod power at each time point planned during the design phase. Generally, a fuel rod has three cycles in its life cycle.

[0043] It can be understood that the design power history of a fuel rod for any cycle represents the power variations of the fuel rod at each time point within that cycle, as planned during the design phase. Because the operating power of the fuel rod is essentially stable within each cycle, the design power history of each fuel rod cycle corresponds to an expected power, resulting in a nearly straight line for each cycle. However, the design power histories for different cycles may be the same or different.

[0044] It's worth noting that determining the design power history requires comprehensive consideration of multiple factors, including the reactor's overall performance requirements, safety standards, fuel rod material properties, and thermal-hydraulic conditions. Due to varying fuel distribution within the core, different fuel rods will have different corresponding design power histories.

[0045] Step 102: Determine the target power and target burnup of the fuel rods in a stable state according to the expected power.

[0046] In this embodiment, power fluctuations during actual operation of the fuel rods are taken into account, and various possible powers and burnups of the fuel rods during actual operation are predicted based on the expected power, thereby improving the comprehensiveness of the PCI performance analysis.

[0047] In one embodiment, the method for determining the fuel rod PCI critical power further includes: performing an offset process on the expected power of at least one operation phase according to a preset offset.

[0048] In this embodiment, the offset is preset to reflect the deviation of the power of the fuel rod in actual operation, so that the expected power after the offset processing can accommodate the possible fluctuation of the power of the fuel rod in actual operation.

[0049] For example, Figure 3 As shown, taking the cyclic design power history in the above embodiment as an example, the design power history (expected power) of at least one cycle (operation phase) is offset by a preset offset to reflect the power fluctuations of the fuel rods at different times, improving the comprehensiveness of the PCI performance analysis. This is manifested by a certain upward and downward fluctuation in the design power history of at least one cycle, and the offset design power history is used as the virtual power history (expected power after offset). It can be understood that the virtual power history (expected power after offset) of any cycle has an envelope of its design power (expected power) history.

[0050] For example, Figure 3 As shown, the three cycles in the fuel rod's life cycle are the first cycle, the second cycle, and the third cycle. The design power history of the first cycle, the second cycle, or the third cycle can be offset to obtain a virtual power history for one cycle. Alternatively, the design power history of the first and second cycles, or the first and third cycles, or the second and third cycles can be offset to obtain a virtual power history for two cycles. Alternatively, the design power history of the first, second, and third cycles can be offset to obtain a virtual power history for three cycles.

[0051] It should be noted that the preset offset can be set based on the design power history of the fuel rod and combined with operational requirements, and can reflect the operating power range of the fuel rod in the actual application scenario. This application does not impose any specific restrictions. For example, the preset offset is ±10% or ±50% of the expected power.

[0052] It's worth noting that in actual application scenarios, if a nuclear reactor needs to change the operating power range of its fuel rods, the preset offset can be adjusted based on actual needs, ensuring that the offset-processed expected power can promptly account for power fluctuations corresponding to actual conditions, thereby improving the timeliness of this embodiment. For example, if a nuclear reactor relaxes the operating power range of its fuel rods, the preset offset can be increased based on the relaxed range, thereby expanding the virtual power history of the fuel rods. This allows subsequent steps to obtain the PCI critical power corresponding to the wider power range.

[0053] Furthermore, as a refinement and expansion of the specific implementation of the above embodiment, and to fully illustrate the specific implementation process of this embodiment, step 102, i.e., the step of determining the target power and target burnup of the fuel rod in a stable state based on the expected power, specifically includes: interpolating or fitting the expected power collected at the sampling moments to determine the target power at the calculation moment; determining the calculation moment between the sampling moments based on a preset time interval; and determining the target burnup at the calculation moment based on the target power at the calculation moment.

[0054] In this embodiment, the expected power at the sampling moment is smoothed and optimized by interpolation or fitting, the power at the unsampled moment is filled, the amount of processed data is reduced, the fuel rod power trend and law are reflected, and the accuracy of the target power is improved.

[0055] For example, sampling times are determined within the fuel rod's lifecycle based on preset sampling intervals. This appropriately preset sampling interval ensures that the expected power collected at each sampling time is representative, avoiding the processing of excessively large and complex continuous data and reducing the burden of data calculation. Furthermore, the expected power at each sampling time is interpolated or fitted to reflect the overall trends and patterns of fuel rod power. This generates smooth and continuous power data between sampling times, thereby determining more accurate power values ​​at each time. This effectively reduces computing resource consumption, improves the accuracy of subsequent critical PCI power calculations, and optimizes the calculation process.

[0056] It should be noted that an appropriate interpolation or fitting method can be selected based on the data characteristics such as the distribution of the expected power collected and the overall trend to ensure the accuracy and effectiveness of the interpolation or fitting results. This application does not impose any specific restrictions.

[0057] Furthermore, the calculation moments between the sampling moments are determined according to a preset time interval. After the expected power at the sampling moments is interpolated or fitted, the power at all moments is not output, but the target power at the calculation moment is output to control the computing resources. The target power is used to accurately represent various steady-state powers that may exist in the fuel rods during actual operation, thereby improving the accuracy and comprehensiveness of this application.

[0058] It should be noted that the preset sampling interval and the preset time interval are determined based on factors such as power fluctuations, computing resources, and accuracy requirements in actual application scenarios, and are not limited in this application. For example, the preset sampling interval can be 1000 hours or 2000 hours to achieve appropriate sampling, and the preset time interval can be 30 hours or 50 hours, etc., so that the target power obtained is more comprehensive and more closely reflects the actual operating conditions of the fuel rods.

[0059] For example, using the design power history and virtual power history of the aforementioned cycle as an example, for cycles where the design power history (expected power) is offset, interpolation or fitting is performed on the virtual power history (expected power after offset) collected at the sampling time to determine the target power at the calculation time. For cycles where the design power history (expected power) is not offset, interpolation or fitting is performed on the design power history (expected power) collected at the sampling time to determine the target power at the calculation time.

[0060] Since the virtual power history reflects the fluctuations of the fuel rods in actual operation and can accommodate possible deviations in the power of the fuel rods in actual operation, the target power obtained based on the virtual power history or design power history of each cycle of the fuel rods can cover various steady-state powers that may exist in the actual operation of the fuel rods.

[0061] The operating status of a fuel rod is typically determined based on both power and burnup at a given moment. Burnup represents the amount of energy released by the fuel rod. Since fuel rod burnup is closely related to fuel rod power, this embodiment, after determining the target power at the calculation moment, further determines the target fuel at the calculation moment based on the target power. This allows multiple different operating points for the fuel rod to be determined based on the target power and target burnup at the calculation moment.

[0062] It should be noted that this embodiment does not specifically limit the method for determining the target fuel consumption. It only needs to be able to obtain an accurate target fuel consumption. This embodiment will not be elaborated on here.

[0063] Furthermore, as a refinement and extension of the specific implementation of the above embodiment, in order to fully illustrate the specific implementation process of this embodiment, before interpolating or fitting the expected power collected at the sampling time, the method also includes: processing the expected power at any sampling time according to the structural parameters of the fuel rod to update the expected power.

[0064] In this embodiment, the expected power at any sampling moment is corrected and optimized in combination with the influence of the structural parameters of the fuel rod on the power generation, thereby obtaining a more precise fuel rod power.

[0065] Exemplarily, the structural parameters of the fuel rods and the expected power at any sampling moment are input into the fuel performance analysis program, and the expected power at the sampling moment is updated according to the power output by the fuel performance analysis program.

[0066] It should be noted that the fuel performance analysis program can output a more detailed power output at a specified time based on the input fuel rod power changes at each time point during operation and the fuel rod structural parameters. For example, by multiplying the average fuel rod power by its distribution along the fuel rod's axial section, the power output for a specific axial section can be output. Fuel rod structural parameters include neutron data (including neutron flux and power distribution along the fuel rod's axial section), external parameters (including coolant pressure, temperature, thermal and hydraulic channel parameters), and internal fuel rod structural parameters (including length, inner and outer diameters, and pre-fill gas pressure).

[0067] Step 103 : transiently changing the target power according to the restriction conditions corresponding to the fuel rod cladding type, and determining the PCI critical power of the fuel rod under the target power and target burnup operation.

[0068] Specifically, the expected power and target power are both the power of the fuel rods when they are operating stably (steady-state power). However, during the actual operation of the fuel rods, different transient processes may occur, causing transient mutations in the steady-state power of the fuel rods, thereby changing the PCI performance of the fuel rods. This can easily lead to PCI performance failure and affect the normal operation of the nuclear reactor.

[0069] In this embodiment, to prevent cladding failure, the impact of transient processes on fuel rods is taken into account. Based on the constraints corresponding to the fuel rod cladding type, the maximum transient change that can occur in the fuel rod under target power and target burnup is determined, thereby determining the PCI critical power. The PCI critical power accurately defines the safety limits of the fuel rod under different steady-state powers and burnups, improving the reliability and comprehensiveness of the fuel rod PCI performance analysis and facilitating the adjustment and control of the actual operation of the fuel rod.

[0070] Further, as a refinement and extension of the above embodiment, in order to fully describe the specific implementation process of the embodiment, the step 103, i.e., the step of determining the PCI critical power of the fuel rod under the target power and target burnup operation according to the limit condition corresponding to the cladding type of the fuel rod, specifically comprises: determining a first power change amount and a second power change amount according to the magnitude of the target power; determining a first transient power according to the target power and the first power change amount; determining a second transient power according to the first transient power and the second power change amount; determining a first index value and a second index value of the influencing factor of the fuel rod under the first transient power and the second transient power, respectively; wherein, if the first index value is less than the critical index value corresponding to the limit condition, and the second index value is greater than the critical index value corresponding to the limit condition, the first transient power corresponding to the first index value is taken as the PCI critical power; if the first index value is greater than or equal to the critical index value corresponding to the limit condition, or the second index value is less than or equal to the critical index value corresponding to the limit condition, the first power change amount is adjusted so that the first index value re-determined according to the adjusted first transient power is less than the critical index value corresponding to the limit condition, and the second index value is greater than the critical index value corresponding to the limit condition.

[0071] In this embodiment, based on the limit condition corresponding to the cladding type, the maximum power that can be reached by the target power is gradually approached in a loop manner, and the PCI critical power corresponding to the target power is finally determined, which improves the calculation efficiency while ensuring the accuracy of the PCI critical power.

[0072] Further, as a refinement and extension of the above embodiment, in order to fully describe the specific implementation process of the embodiment, if the first index value is greater than or equal to the critical index value corresponding to the limit condition, or the second index value is less than or equal to the critical index value corresponding to the limit condition, the step of adjusting the first power change amount specifically comprises: if the first index value is greater than or equal to the critical index value corresponding to the limit condition, decreasing the first power change amount according to a preset power correction amount; if the second index value is less than or equal to the critical index value corresponding to the limit condition, increasing the first power change amount according to the preset power correction amount.

[0073] In this embodiment, by adjusting the first power change amount through the preset power correction amount, the variation range of the first transient power is controlled, so that the variation of the first transient power has certain regularity and controllability, ensuring the rationality of the first transient power adjustment, reducing unnecessary power testing, and saving calculation resources and time.

[0074] Specifically, a first power change ΔP1 and a second power change ΔP2 are determined based on the magnitude of the target power P. These values ​​provide a reference for reasonable power changes, avoiding inaccurate or inefficient calculations caused by excessively large or small power changes. Furthermore, the first power change ΔP1 is used to transiently change the steady-state target power P, adjusting it to different transient power levels. The second power change ΔP2 ensures the accuracy of the PCI critical power. For example, the operating power of fuel rods typically ranges from 10 to 50 kW / m. If, at a given calculation moment, the target power P is 30 kW / m and the target burnup is BMW d / tU, the first power change ΔP1 can be determined to a value such as 10 kW / m based on the magnitude of the target power P. Depending on the accuracy requirements for the PCI critical power in actual application scenarios, the second power change ΔP2 can be determined to a value such as 1 kW / m or 0.1 kW / m.

[0075] For example, to achieve a stepwise approximation, a first transient power is first determined based on the target power P and the first power change ΔP1. A first index value of the influencing factor of the fuel rod at this first transient power is then determined, providing baseline data for subsequent adjustments and optimizations. The first index value of the influencing factor is used to evaluate the PCI performance of the fuel rod at this first transient power. The influencing factor includes at least one of the following: cladding strain, fuel temperature, cladding strain energy density, and cladding TRESCA stress.

[0076] It should be noted that the PCI performance of fuel rods at different transient power levels can be calculated using a fuel performance analysis program. Based on the input power variations at each time point during fuel rod operation and the aforementioned fuel rod structural parameters, the program uses a corresponding analysis model to output performance parameters such as fuel rod burnup, fuel temperature, cladding stress and strain, fuel rod internal pressure, and cladding corrosion at a specified time.

[0077] It's worth noting that when evaluating PCI performance, one or more evaluation criteria need to be determined based on the different grades of fuel rod cladding materials (cladding types). For example, these criteria include fuel temperature, cladding strain, cladding strain energy density, and cladding TRESCA stress. The fuel temperature criterion prevents excessive melting of fuel pellets, which in turn imposes greater stress on the cladding. The cladding strain criterion prevents failures due to excessive cladding strain under transient conditions. The cladding strain energy density criterion prevents failures due to excessive cladding strain energy density under transient conditions. The cladding TRESCA stress criterion prevents failures due to excessive TRESCA stress under transient conditions.

[0078] Exemplarily, the evaluation criteria that the fuel rod cladding type complies with are used as the constraint conditions corresponding to the fuel rod cladding type, and critical indicator values ​​corresponding to the constraint conditions are determined based on the evaluation criteria that the fuel rod cladding type complies with. For example, the critical indicator value corresponding to the fuel temperature criterion is that the fuel temperature does not exceed 2590°C, the critical indicator value corresponding to the cladding strain criterion is that the transient cladding strain change (i.e., the cladding strain after the transient minus the cladding strain before the transient) is less than 1%, the critical indicator value corresponding to the cladding strain energy density criterion is that the cladding strain energy density does not exceed 2.87 MPa, and the critical indicator value corresponding to the cladding TRESCA stress criterion is that the cladding TRESCA stress does not exceed 535 MPa.

[0079] It should be noted that if the fuel rod cladding type meets multiple evaluation criteria, the evaluation criterion that has the greatest restriction on the fuel rods will be used as the restriction condition to obtain the lowest PCI critical power among the PCI critical powers corresponding to the multiple evaluation criteria to ensure the safe operation of the fuel rods.

[0080] For example, if the cladding strain criterion is used as a constraint condition, the first index value of the influencing factor of the fuel rod at the first transient power is the first cladding strain change.

[0081] Furthermore, in order to determine the maximum transient power corresponding to the fuel rod when operating at the target power P and the target burnup B and meeting the constraint conditions, it is necessary to continuously adjust the first power change ΔP1 to change the first transient power, so that the first indicator value determined based on the first transient power gradually approaches the critical indicator value until the PCI critical power is determined.

[0082] Specifically, if the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, it indicates that the first transient power has exceeded the maximum transient power allowed by the constraint condition. In this case, it is necessary to appropriately adjust the first power variation ΔP1 so that the first transient power gradually approaches the maximum transient power allowed by the constraint condition while meeting the constraint condition.

[0083] Exemplarily, if the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, the first power variation ΔP1 is adjusted, and the magnitude relationship between the first indicator value re-determined based on the adjusted first transient power and the critical indicator value corresponding to the constraint condition is determined.

[0084] The first power variation ΔP1 is gradually corrected according to the preset power correction amount, so as to efficiently find the transient power close to the critical value.

[0085] It should be noted that the change in power means the change in energy in a short time, and therefore the index value of the influencing factor will also change accordingly with the change in power. For example, a large increase in transient power means a rapid release of energy in a short time, and such rapid energy change will have a stronger impact on the cladding and cause the index value to increase.

[0086] For example, if the first index value is greater than or equal to the critical index value corresponding to the limit condition, the first power change amount ΔP1 is reduced according to a preset power correction amount, so that the first transient power is appropriately reduced, and the size relationship between the first index value re-determined according to the reduced first transient power and the critical index value corresponding to the limit condition is determined.

[0087] It is worth mentioning that the preset power correction amount can be determined according to the difference between the first index value and the critical index value corresponding to the limit condition, so as to appropriately adjust the first transient power and avoid excessive calculation times caused by excessively large or small power change amounts. For example, if the first index value and the critical index value corresponding to the limit condition are relatively close, the preset power correction amount can be determined as 1 kW / m or 0.1 kW / m, etc., so as to gradually reduce the gap between the first transient power and the maximum transient power allowed by the limit condition. If the difference between the first index value and the critical index value corresponding to the limit condition is large, the preset power correction amount can be determined as 5 kW / m or 8 kW / m, etc. according to the first power change amount ΔP1, so as to quickly approach the maximum transient power allowed by the limit condition.

[0088] Further, if the first index value is less than the critical index value corresponding to the limit condition, it indicates that the first transient power meets the limit of the limit condition, but it is necessary to further determine whether the first transient power is already very close to the maximum transient power allowed by the limit condition.

[0089] For example, if the first index value is less than the critical index value corresponding to the limit condition, the second transient power is determined according to the first transient power and the second power change amount ΔP2, and the second index value of the influencing factor of the fuel rod under the second transient power is determined. The second index value of the influencing factor is used to evaluate the PCI performance of the fuel rod under the second transient power.

[0090] It can be understood that the second index value is the same as the first index value. For example, if the cladding strain criterion is used as the limit condition, the second index value of the influencing factor of the fuel rod under the second transient power is the second cladding strain change amount.

[0091] Specifically, if the second indicator value is less than the critical indicator value corresponding to the constraint condition, it means that although the increased first transient power meets the constraint condition, there is still a certain gap between the first transient power and the maximum transient power allowed by the constraint condition, and the accuracy corresponding to the second power change ΔP2 is not reached. In this case, the first power change ΔP1 needs to be further adjusted to make the first transient power closer to the maximum transient power allowed by the constraint condition.

[0092] For example, similar to the above-mentioned reduction of the first power change △P1, if the second index value is less than the critical index value corresponding to the constraint condition, the first power change △P1 is increased according to the preset power correction amount to increase the first transient power, and the size relationship between the first index value re-determined according to the increased first transient power and the critical index value corresponding to the constraint condition is determined.

[0093] If the second indicator value is greater than the critical indicator value corresponding to the constraint, it means that a slight increase in power from the first transient power would exceed the constraint. Therefore, it is determined that the first transient power is very close to the maximum transient power allowed by the constraint and meets the accuracy corresponding to the second power change ΔP2. Therefore, the PCI critical power of the fuel rod at the target power P and target burnup B is determined based on the first transient power at this time.

[0094] Exemplarily, if the first indicator value is smaller than the critical indicator value corresponding to the constraint condition, and the second indicator value is larger than the critical indicator value corresponding to the constraint condition, the first transient power corresponding to the first indicator value is used as the PCI critical power.

[0095] It can be understood that if the first indicator value and the second indicator value do not simultaneously satisfy the first indicator value less than the critical indicator value corresponding to the constraint condition, and the second indicator value is greater than the critical indicator value corresponding to the constraint condition, the above cycle needs to be repeated until the PCI critical power is determined according to the target power P.

[0096] It's worth noting that if multiple target powers P are close, the PCI critical power corresponding to one of these close targets can be calculated. This represents the PCI critical power corresponding to all close targets, thus saving computational resources. Similarly, if the target powers P and target burnup B for multiple fuel rods overlap, the PCI critical power corresponding to one of these overlapping fuel rods can be calculated.

[0097] In one embodiment, the method for determining the fuel rod PCI critical power further includes: determining a PCI critical power database of the nuclear reactor core based on the PCI critical power; obtaining the actual power and actual burnup of the fuel rod at the monitoring time; calling a target PCI critical power in the PCI critical power database that matches the actual power and actual burnup of the fuel rod; and generating a warning message if the difference between the actual power of the fuel rod and the target PCI critical power does not meet a preset threshold condition.

[0098] In this embodiment, a PCI critical power database of the nuclear reactor core is established based on the PCI critical power. The PCI critical power database is used to monitor the actual power and actual burnup of each fuel rod online to ensure the normal operation of the nuclear reactor.

[0099] Specifically, a PCI critical power database for each fuel rod in the entire core is established based on the PCI critical power of each fuel rod at the target power P and target fuel. This database is then fed back to the nuclear reactor's online monitoring system for use. The online monitoring system monitors the actual power and burnup of each fuel rod in the nuclear reactor in real time. By interpolating, searching, and mapping the PCI critical power database, the target PCI critical power corresponding to the fuel rod's actual power reaching its PCI performance limit is retrieved. The core is then adjusted and controlled based on the target PCI critical power to prevent PCI performance failures in the fuel rods.

[0100] For example, if the difference between the actual power of the fuel rod and the target PCI critical power does not meet the preset threshold condition, an early warning message is generated to achieve effective monitoring of each fuel rod of the nuclear reactor and ensure the normal operation of the nuclear reactor.

[0101] Among them, the preset threshold conditions can be specifically set according to factors such as the safety design standards of the nuclear reactor or the performance characteristics of the fuel rods, so as to ensure that the fuel rods can operate safely within a reasonable power deviation range. This application does not impose any specific restrictions.

[0102] It is worth mentioning that according to the margin between the actual power of the fuel rods and the target PCI critical power, some low-power fuel rods can be controlled to appropriately increase the power operation, thereby improving the economy of the nuclear power plant and the utilization rate of nuclear fuel.

[0103] It should be noted that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0104] Furthermore, if Figure 2As shown, as a specific implementation of the above-mentioned fuel rod PCI critical power determination method, an embodiment of the present application provides a fuel rod PCI critical power determination device 200, and the fuel rod PCI critical power determination device 200 includes: an acquisition module 201 and a determination module 202.

[0105] The acquisition module 201 is used to obtain the expected power of the fuel rods in the nuclear reactor core at each operating stage during the life cycle.

[0106] A determination module 202 is configured to determine a target power and a target burnup of the fuel rods in a stable state according to the expected power;

[0107] Furthermore, the target power is transiently changed according to the restriction conditions corresponding to the fuel rod cladding type to determine the PCI critical power of the fuel rod under the target power and target burnup operation.

[0108] In one embodiment, the determination module 202 is specifically configured to: perform a transient change on the target power according to the constraint corresponding to the cladding type of the fuel rod, and determine the PCI critical power of the fuel rod under the target power and target burnup operation, including: determining a first power change amount and a second power change amount according to the magnitude of the target power; determining a first transient power according to the target power and the first power change amount; determining a second transient power according to the first transient power and the second power change amount; and respectively determining a first index value and a second index value of an influencing factor of the fuel rod under the first transient power and the second transient power operation; wherein, if the first index value is less than the critical index value corresponding to the constraint and the second index value is greater than the critical index value corresponding to the constraint, the first transient power corresponding to the first index value is used as the PCI critical power; and if the first index value is greater than or equal to the critical index value corresponding to the constraint, or the second index value is less than or equal to the critical index value corresponding to the constraint, adjusting the first power change amount so that the first index value re-determined based on the adjusted first transient power is less than the critical index value corresponding to the constraint and the second index value is greater than the critical index value corresponding to the constraint.

[0109] In one embodiment, the determination module 202 is specifically used to: if the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, or the second indicator value is less than or equal to the critical indicator value corresponding to the constraint condition, adjust the first power change amount, including: if the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, reduce the first power change amount according to the preset power correction amount; if the second indicator value is less than or equal to the critical indicator value corresponding to the constraint condition, increase the first power change amount according to the preset power correction amount.

[0110] In one embodiment, the determination module 202 is specifically configured to: the influencing factors include at least one of the following: cladding strain, fuel temperature, cladding strain energy density, and cladding TRESCA stress.

[0111] In one embodiment, the fuel rod PCI critical power determination device further includes:

[0112] The offset module is specifically configured to perform offset processing on the expected power of at least one operating stage according to a preset offset amount.

[0113] In one embodiment, the determination module 202 is configured to: interpolate or fit the expected power collected at the sampling moments to determine the target power at the calculation moment; wherein the calculation moment between the sampling moments is determined according to a preset time interval; and the target fuel consumption at the calculation moment is determined according to the target power at the calculation moment.

[0114] In one embodiment, the fuel rod PCI critical power determination device further includes:

[0115] The updating module is specifically used to: before interpolating or fitting the expected power collected at the sampling moment, it also includes processing the expected power at any sampling moment according to the structural parameters of the fuel rod to update the expected power.

[0116] In one embodiment, the fuel rod PCI critical power determination device further includes:

[0117] The early warning module is specifically used to: determine the PCI critical power database of the nuclear reactor core based on the PCI critical power; obtain the actual power and actual burnup of the fuel rods at the monitoring time; call the target PCI critical power in the PCI critical power database that matches the actual power and actual burnup of the fuel rods; and generate an early warning message if the difference between the actual power of the fuel rods and the target PCI critical power does not meet the preset threshold conditions.

[0118] The specific definitions of the fuel rod PCI critical power determination device can be found in the definitions of the fuel rod PCI critical power determination method described above and will not be further elaborated here. Each module in the aforementioned fuel rod PCI critical power determination device can be implemented in whole or in part via software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor within a computer device in hardware form, or stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0119] Based on this understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, USB flash drive, mobile hard disk, etc.), and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods of various implementation scenarios of the present application.

[0120] In order to achieve the above-mentioned purpose, the embodiment of the present application further provides a computer device, which can be a personal computer, a server, a network device, etc., and the computer device includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to achieve the above-mentioned Figure 1 The fuel rod PCI critical power determination method is shown.

[0121] In one embodiment, the computer device may further include a user interface, a network interface, a camera, a radio frequency (RF) circuit, a sensor, an audio circuit, a Wi-Fi module, etc. The user interface may include a display, an input unit such as a keyboard, etc., and the optional user interface may also include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a Bluetooth interface, a Wi-Fi interface), etc.

[0122] Those skilled in the art will understand that the computer device structure provided in this embodiment does not constitute a limitation on the computer device, and may include more or fewer components, or a combination of certain components, or different component arrangements.

[0123] The storage medium may also include an operating system and a network communication module. An operating system is a program that manages and stores the hardware and software resources of a computer device, supporting the execution of information processing programs and other software and / or programs. The network communication module facilitates communication between components within the storage medium, as well as with other hardware and software within the physical device.

[0124] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present application can be implemented with the help of software plus the necessary general hardware platform, and can also implement the embodiments of the present application through hardware.

[0125] Those skilled in the art will understand that the accompanying drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the accompanying drawings are not necessarily required to implement the present application. Those skilled in the art will understand that the modules in the devices in the implementation scenario can be distributed in the devices of the implementation scenario according to the implementation scenario description, or can be changed accordingly and located in one or more devices different from the implementation scenario. The modules of the above-mentioned implementation scenario can be combined into one module, or can be further split into multiple sub-modules.

[0126] The serial numbers of the above application are for descriptive purposes only and do not represent the advantages or disadvantages of the implementation scenarios. The above disclosure only discloses several specific implementation scenarios of the present application, but the present application is not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present application.

Claims

1. A method for determining fuel rod PCI critical power, characterized in that: The method comprises: Obtain the expected power of the fuel rods in the nuclear reactor core at each operating stage during its life cycle; determining a target power and a target burnup of the fuel rod in a stable state according to the expected power; transiently changing the target power according to the restriction conditions corresponding to the cladding type of the fuel rod, and determining the PCI critical power of the fuel rod under the target power and target burnup operation; The transiently changing the target power according to the restriction condition corresponding to the cladding type of the fuel rod to determine the PCI critical power of the fuel rod under the target power and target burnup operation includes: Determining a first power variation and a second power variation according to the magnitude of the target power; determining a first transient power according to the target power and the first power variation; determining a second transient power according to the first transient power and the second power variation; Determining first and second index values ​​of factors affecting the fuel rod under the first and second transient power operation conditions, respectively; wherein, If the first indicator value is less than the critical indicator value corresponding to the constraint condition, and the second indicator value is greater than the critical indicator value corresponding to the constraint condition, using the first transient power corresponding to the first indicator value as the PCI critical power; If the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, or the second indicator value is less than or equal to the critical indicator value corresponding to the constraint condition, adjusting the first power variation so that the first indicator value re-determined based on the adjusted first transient power is less than the critical indicator value corresponding to the constraint condition, and the second indicator value is greater than the critical indicator value corresponding to the constraint condition; If the first indicator value is greater than or equal to the critical indicator value corresponding to the restriction condition, or the second indicator value is less than or equal to the critical indicator value corresponding to the restriction condition, adjusting the first power variation includes: If the first indicator value is greater than or equal to the critical indicator value corresponding to the restriction condition, reducing the first power variation according to a preset power correction amount; If the second indicator value is less than or equal to the critical indicator value corresponding to the restriction condition, increasing the first power change amount according to the preset power correction amount; The influencing factors include at least one of the following: cladding strain, fuel temperature, cladding strain energy density and cladding TRESCA stress.

2. The method for determining fuel rod PCI critical power according to claim 1, characterized in that: The method further comprises: The expected power of at least one of the operating stages is offset according to a preset offset.

3. The method for determining fuel rod PCI critical power according to claim 1, characterized in that: Determining the target power and target burnup of the fuel rod in a stable state according to the expected power includes: Performing interpolation or fitting processing on the expected power collected at the sampling moments to determine the target power at the calculation moment; wherein the calculation moment between the sampling moments is determined according to a preset time interval; The target fuel consumption at the calculation time is determined based on the target power at the calculation time.

4. The method for determining fuel rod PCI critical power according to claim 3, characterized in that: Before performing interpolation or fitting processing on the expected power collected at the sampling moment, the method further includes: The expected power at any sampling moment is processed according to the structural parameters of the fuel rod to update the expected power.

5. The method for determining fuel rod PCI critical power according to claim 1, characterized in that: The method further comprises: Determining a PCI critical power database of the nuclear reactor core according to the PCI critical power; Obtaining the actual power and actual burnup of the fuel rod at the monitoring moment; Retrieving a target PCI critical power from the PCI critical power database that matches the actual power and actual burnup of the fuel rod; If the difference between the actual power of the fuel rod and the target PCI critical power does not meet the preset threshold condition, an early warning message is generated.

6. A fuel rod PCI critical power determination device, characterized in that: The device comprises: An acquisition module, used to obtain the expected power of the fuel rods in the nuclear reactor core at various operating stages during their life cycle; a determination module, configured to determine a target power and a target burnup of the fuel rod in a stable state according to the expected power; and The target power is transiently changed according to the restriction conditions corresponding to the cladding type of the fuel rod to determine the PCI critical power of the fuel rod under the target power and target burnup operation; the target power is transiently changed according to the restriction conditions corresponding to the cladding type of the fuel rod to determine the PCI critical power of the fuel rod under the target power and target burnup operation, including: determining a first power change amount and a second power change amount according to the magnitude of the target power; determining a first transient power according to the target power and the first power change amount; determining a second transient power according to the first transient power and the second power change amount; respectively determining the fuel rod at the first transient power and the second transient power; a first indicator value and a second indicator value of an influencing factor under the second transient power operation; wherein, if the first indicator value is less than the critical indicator value corresponding to the constraint condition, and the second indicator value is greater than the critical indicator value corresponding to the constraint condition, the first transient power corresponding to the first indicator value is used as the PCI critical power; if the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, or the second indicator value is less than or equal to the critical indicator value corresponding to the constraint condition, the first power change amount is adjusted so that the first indicator value re-determined based on the adjusted first transient power is less than the critical indicator value corresponding to the constraint condition, and the second indicator value is greater than the critical indicator value corresponding to the constraint condition; If the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, or the second indicator value is less than or equal to the critical indicator value corresponding to the constraint condition, adjusting the first power variation includes: if the first indicator value is greater than or equal to the critical indicator value corresponding to the constraint condition, reducing the first power variation according to a preset power correction amount; if the second indicator value is less than or equal to the critical indicator value corresponding to the constraint condition, increasing the first power variation according to the preset power correction amount; The influencing factors include at least one of the following: cladding strain, fuel temperature, cladding strain energy density and cladding TRESCA stress.

7. A computer device comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, wherein: When the processor executes the program, the method for determining the fuel rod PCI critical power according to any one of claims 1 to 5 is implemented.

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