A method and system for nuclear reactor nuclear fuel reliability assessment

Abstract

The present application relates to a kind of nuclear reactor nuclear fuel reliability evaluation method and system, comprising the following steps: general nuclear fuel evaluation is carried out to nuclear reactor nuclear fuel, and the change classification of the nuclear fuel attribute of general nuclear fuel is obtained;Whether the non-general nuclear fuel evaluation needs to be carried out is judged according to the change classification of the nuclear fuel attribute of general nuclear fuel;If yes, then non-general nuclear fuel evaluation is carried out to nuclear reactor nuclear fuel;If no, then check file record and nuclear fuel performance margin record.The present application can predict the probability of nuclear fuel damage in the future before the nuclear fuel damage occurs, avoid the nuclear fuel damage in operation, thereby avoid the major operating event of nuclear power plant due to nuclear fuel damage or abnormal performance problem, improve the safety and reliability of nuclear power plant.

Description

Technical Field

[0001] This invention relates to the technical field of nuclear reactors in nuclear power plants, and more specifically, to a method and system for assessing the reliability of nuclear fuel in nuclear reactors. Background Technology

[0002] Nuclear reactor fuel reliability refers to the probability of nuclear fuel assemblies breaking during reactor operation. Currently, nuclear reactors use the FRI (Fuel Reliability Index) to monitor whether fuel cladding has broken. The FRI is mainly calculated by measuring the radioactivity of fission products I-131 and I-134 in the primary coolant (domestic nuclear power plants mainly monitor the integrity of the fuel cladding by detecting radiochemical data in the primary coolant), and is given based on experience.

[0003] Currently, nuclear reactor fuel reliability is still largely dependent on improvements to fuel assembly design and materials. Furthermore, while calculating the Free Rate Intake (FRI) using primary loop radiochemical data to determine if nuclear fuel has suffered damage, there is no assessment to predict the probability of future fuel damage before such damage has occurred. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for assessing the reliability of nuclear fuel in nuclear reactors, addressing the shortcomings of existing technologies.

[0005] The technical solution adopted by this invention to solve its technical problem is: constructing a method for assessing the reliability of nuclear reactor fuel, comprising the following steps:

[0006] A universal nuclear fuel assessment is conducted on the nuclear reactor fuel to obtain a classification of changes in the nuclear fuel properties of the universal nuclear fuel;

[0007] Whether a non-universal nuclear fuel assessment is needed is determined based on the classification of changes in the nuclear fuel properties of the general nuclear fuel.

[0008] If so, a non-universal nuclear fuel assessment will be conducted on the nuclear reactor fuel;

[0009] If not, check the documentation and nuclear fuel performance margin records.

[0010] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the step of performing a universal nuclear fuel assessment on the nuclear reactor nuclear fuel and obtaining the classification of changes in the nuclear fuel properties of the universal nuclear fuel includes:

[0011] An assessment of the nuclear fuel construction phase of the nuclear reactor is conducted.

[0012] An assessment of the nuclear fuel operation phase of the nuclear reactor is conducted.

[0013] An assessment of the post-fuel unloading phase of the nuclear reactor;

[0014] The changes in the nuclear fuel properties of the general nuclear fuel are classified.

[0015] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the nuclear fuel construction phase of the nuclear reactor nuclear fuel includes:

[0016] To obtain parameters for the design and construction process of nuclear fuel;

[0017] The evaluation is based on parameters from the design and construction process of the nuclear fuel.

[0018] In the nuclear reactor nuclear fuel reliability assessment method described in this invention, the parameters of the nuclear fuel design and construction process include:

[0019] Fuel pellets, absorbers, fuel rods, casing, end plugs, spring devices, filling gas, grids, guide sleeves, instrument tubes, upper and lower tube seats, assembly compression springs, assembly design and manufacturing processes.

[0020] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the nuclear fuel operation phase of the nuclear reactor nuclear fuel includes:

[0021] An assessment is conducted on the operational monitoring of the nuclear fuel in the aforementioned nuclear reactor;

[0022] An assessment is conducted to monitor the operating environment of the nuclear reactor fuel.

[0023] An evaluation is conducted on the core design and operational strategy of the nuclear reactor fuel.

[0024] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the operation monitoring of the nuclear reactor nuclear fuel includes:

[0025] To obtain core data for routine or overhaul physics tests of nuclear fuel;

[0026] The evaluation is based on core data from routine or overhaul physics tests of the nuclear fuel.

[0027] In the nuclear reactor nuclear fuel reliability assessment method described in this invention, the core data from routine or overhaul physical tests of the nuclear fuel include:

[0028] Component average power, quadrant power tilt, hot spot factor, enthalpy rise factor, radial peak factor, and critical boron concentration.

[0029] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the operating environment monitoring of the nuclear reactor nuclear fuel includes:

[0030] Obtain key fuel performance characteristic parameters of primary loop water chemistry;

[0031] The evaluation was conducted based on the key fuel performance characteristic parameters of the primary loop water chemistry.

[0032] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the reactor core design and operation strategy supervision of the nuclear reactor nuclear fuel includes:

[0033] To obtain key fuel performance parameters for the core design and operation strategy of the nuclear reactor fuel;

[0034] The evaluation is based on the key fuel performance parameters of the core design and operation strategy.

[0035] In the nuclear reactor nuclear fuel reliability assessment method described in this invention, the key fuel performance parameters of the core design and operation strategy include:

[0036] Cycle strategy, burnup, core flow rate, coolant temperature, power boost, peak factor and operating strategy.

[0037] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the nuclear reactor nuclear fuel after unloading includes:

[0038] Assessment of nuclear fuel baseline testing;

[0039] Assess the monitoring of abnormal nuclear fuel conditions;

[0040] Assess and evaluate other events related to nuclear fuel.

[0041] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of nuclear fuel baseline detection includes:

[0042] To acquire events that occur during the nuclear fuel operating cycle that affect the nuclear fuel;

[0043] To obtain parameters that adversely affect the reliability of nuclear fuel;

[0044] Acquire overall abnormal events and parameters during the nuclear fuel operating cycle;

[0045] An assessment is conducted based on the events that affect nuclear fuel, the parameters that adversely affect nuclear fuel reliability, and the overall abnormal events and parameters in the nuclear fuel operating cycle.

[0046] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of monitoring abnormal nuclear fuel conditions includes:

[0047] Acquire the abnormal nuclear fuel data;

[0048] Anomaly monitoring and assessment are conducted based on the aforementioned nuclear fuel anomaly data.

[0049] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the nuclear fuel anomaly data includes:

[0050] Axial offset data, previous data on incomplete insertion of the circulation rod, previous data on fuel loading and unloading issues, component structure issues, and transportation issues.

[0051] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of monitoring other nuclear fuel events includes:

[0052] Obtain other event data related to nuclear fuel;

[0053] Other event monitoring and assessment will be conducted based on the aforementioned nuclear fuel other event data.

[0054] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the other event data of the nuclear fuel include:

[0055] Data on power plant renovation, power plant anomalies, and changes in reactor water purification.

[0056] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of non-universal nuclear fuel in the nuclear reactor includes:

[0057] Assess the internal margins of the nuclear fuel cladding in nuclear reactors;

[0058] Assess the external margin of the nuclear fuel cladding in the nuclear reactor.

[0059] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the internal margin of the nuclear reactor nuclear fuel cladding includes:

[0060] Obtain parameters of the interaction effect between the fuel core and the cladding;

[0061] The internal margin of the nuclear reactor fuel cladding is evaluated based on the parameters of the interaction effect between the fuel core and the cladding.

[0062] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the interaction effect parameters between the fuel core and the cladding include:

[0063] Core design parameters, power operation parameters, and fuel rod design parameters.

[0064] In the nuclear reactor nuclear fuel reliability assessment method described in this invention, the core design parameters include: node power peak, node ignition loss, power control of ΔI axial power, power control rods, cycle period, long-term low power, operation, core average power, and loading mode.

[0065] The power operation parameters include: power threshold, power rise rate, control rod lifting rate, constant power duration, and axial power offset control.

[0066] The fuel rod design parameters include: cladding material, pellet thermal creep, cladding thermal creep, cladding irradiation creep, cladding thickness, pellet-cladding gap, fuel rod internal pressure, pellet defects, and pellet density.

[0067] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of the external margin of the nuclear reactor nuclear fuel cladding includes:

[0068] Evaluation of micro-vibration wear on grid-fuel rods;

[0069] Assess corrosion or scaling;

[0070] The deformation of the fuel assembly was assessed.

[0071] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of micro-vibration wear of the grid-fuel rod includes:

[0072] To obtain recent event data, risk assessment data, core design and operation strategy data, and fuel design data for nuclear fuel;

[0073] The micro-vibration wear of the grid-fuel rods is assessed based on recent event data, risk assessment data, core design and operation strategy data, and fuel design data.

[0074] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of corrosion or scaling includes:

[0075] Obtain recent event information on cladding corrosion or structure, water chemistry information, risk calculation information, core information, and design and operation strategy information;

[0076] The corrosion or scaling is assessed based on recent event information, water chemistry information, risk calculation information, core information, and design and operation strategy information of the cladding corrosion or structure.

[0077] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of fuel assembly deformation includes:

[0078] Obtain the deformation properties of the fuel assembly;

[0079] The deformation parameters affecting the fuel assembly are determined based on the deformation properties of the fuel assembly.

[0080] The deformation of the fuel assembly is evaluated based on the deformation parameters that affect the fuel assembly.

[0081] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment of non-universal nuclear fuel for the nuclear reactor further includes:

[0082] To obtain the nuclear fuel performance margin of the nuclear reactor fuel;

[0083] The assessment is based on the aforementioned nuclear fuel performance margin.

[0084] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the assessment based on the nuclear fuel performance margin includes:

[0085] The nuclear fuel performance margin is compared with a reference threshold.

[0086] The evaluation is based on the comparison between the nuclear fuel performance margin and the reference threshold.

[0087] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the reference threshold includes: a high threshold and a low threshold;

[0088] The evaluation based on the comparison between the nuclear fuel performance margin and the reference threshold includes:

[0089] If the nuclear fuel performance margin is greater than or equal to the high threshold, then the nuclear fuel performance is determined to be normal.

[0090] If the nuclear fuel performance margin is less than or equal to the low threshold, the nuclear fuel performance is determined to be low.

[0091] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the method further includes:

[0092] If the nuclear fuel performance is determined to be low, then determine whether the nuclear fuel performance is within a preset range;

[0093] If the performance of the nuclear fuel is within the preset range, then the nuclear fuel is determined to meet the reliability integrity condition;

[0094] If the performance of the nuclear fuel is not within the preset range, the nuclear fuel is determined to have low reliability.

[0095] In the nuclear reactor nuclear fuel reliability assessment method of the present invention, the method further includes:

[0096] If the nuclear fuel performance is normal, then the nuclear fuel will be designed or refueled in a normal or standard reactor core.

[0097] If the nuclear fuel has low reliability, then the nuclear fuel will not be subjected to normal or standard core design / refueling.

[0098] The present invention also provides a nuclear reactor nuclear fuel reliability assessment system, comprising:

[0099] A universal assessment unit is used to perform universal nuclear fuel assessment on nuclear reactor nuclear fuel and obtain the classification of changes in the nuclear fuel properties of the universal nuclear fuel;

[0100] The judgment unit is used to classify and determine whether a non-universal nuclear fuel assessment is required based on the changes in the nuclear fuel properties of the universal nuclear fuel.

[0101] Non-universal evaluation unit, used to evaluate non-universal nuclear fuel in nuclear reactors;

[0102] The recording unit is used to check the documentation and nuclear fuel performance margin records when non-universal nuclear fuel assessments are not required.

[0103] The nuclear reactor nuclear fuel reliability assessment method and system of the present invention have the following beneficial effects: The method includes the following steps: performing a general nuclear fuel assessment on the nuclear reactor nuclear fuel to obtain a classification of changes in the general nuclear fuel properties; determining whether a non-general nuclear fuel assessment is needed based on the classification of changes in the general nuclear fuel properties; if so, performing a non-general nuclear fuel assessment on the nuclear reactor nuclear fuel; if not, checking the documentation and nuclear fuel performance margin records. This invention can predict the probability of future nuclear fuel failure by using nuclear fuel performance margins before nuclear fuel failure occurs, thus avoiding nuclear fuel failure during operation and preventing major operational events at the nuclear power plant due to nuclear fuel failure or abnormal performance problems, thereby improving the safety and reliability of the nuclear power plant. Attached Figure Description

[0104] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0105] Figure 1 This is a schematic flowchart of the nuclear reactor nuclear fuel reliability assessment method provided in the embodiments of the present invention;

[0106] Figure 2 This is a schematic diagram of the structure of the nuclear reactor nuclear fuel reliability assessment system provided in an embodiment of the present invention. Detailed Implementation

[0107] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0108] refer to Figure 1 This is a schematic flowchart of an optional embodiment of the nuclear reactor nuclear fuel reliability assessment method provided by the present invention.

[0109] like Figure 1 As shown, the nuclear reactor nuclear fuel reliability assessment method includes the following steps:

[0110] Step S101: Perform a universal nuclear fuel assessment on the nuclear reactor fuel to obtain the classification of changes in the nuclear fuel properties of the universal nuclear fuel.

[0111] In this embodiment of the invention, the evaluation of nuclear reactor nuclear fuel using universal nuclear fuel (non-destructible fuel) to obtain the classification of changes in the nuclear fuel properties of the universal nuclear fuel includes: evaluating the nuclear fuel construction phase of the nuclear reactor nuclear fuel; evaluating the nuclear fuel operation phase of the nuclear reactor nuclear fuel; evaluating the post-nuclear fuel unloading phase of the nuclear reactor nuclear fuel; and obtaining the classification of changes in the nuclear fuel properties of the universal nuclear fuel.

[0112] Specifically, the nuclear fuel construction phase mainly focuses on new fuel assemblies, checking parameters of the fuel design and construction process based on the fuel manufacturing end. The nuclear fuel operation phase mainly involves continuous evaluation of the nuclear fuel during reactor operation. The post-fuel unloading phase mainly involves evaluation of spent fuel (used nuclear fuel).

[0113] Optionally, in this embodiment of the invention, evaluating the nuclear fuel construction phase of the nuclear reactor includes: obtaining parameters of the design and construction process of the nuclear fuel; and evaluating based on the parameters of the design and construction process of the nuclear fuel.

[0114] The parameters for the design and construction process of nuclear fuel include: fuel pellets, absorber, fuel rods, cladding, end plugs, spring devices, filling gas, grid, guide sleeves, instrumentation tubes, upper tube seat, lower tube seat, assembly compression springs, and assembly design and manufacturing processes.

[0115] Specifically, for fuel pellets, the evaluation primarily focuses on changes in their material, composition, geometry, or density. For absorbers, the evaluation primarily focuses on changes in their material, composition, geometry, or density. For fuel rods, the evaluation primarily focuses on changes in fuel rod dimensions (such as length, diameter, or wall thickness). For cladding, the evaluation primarily focuses on changes in alloy composition or heat treatment. For end plugs, the evaluation primarily focuses on changes in alloy, heat treatment, end plug design, or weld morphology (changes in circumferential welds and / or sealing welds). For spring assemblies, the evaluation primarily focuses on changes in material, axial arrangement of the cap or forces acting on the pellet columns, and end plug or cladding ID. For filling gases, the evaluation primarily focuses on changes in the main gas pressure or gas composition. For grids, the evaluation primarily focuses on changes in alloy, rod contact geometry or characteristics, frame connection mechanism, mixing blade style or design, or pressure drop. For guide sleeves, the evaluation primarily focuses on changes in alloy, heat treatment, design (wall thickness, length, or buffer), or grid connection mechanism or seat. For instrument tubes, the evaluation primarily focuses on changes in alloy, heat treatment, or design. For the upper tube seat, the evaluation primarily focuses on changes in materials, flow paths or flow areas, or skeleton connectors. For the lower tube seat, the evaluation primarily focuses on changes in materials, flow paths or flow areas, debris filters, or skeleton connectors. For the component clamping spring, the evaluation primarily focuses on changes in materials, design, or axial loads on the skeleton. For the component design, the evaluation primarily focuses on changes in the number of grids or intermediate grids, the axial distribution of grids, or the load-bearing path. For the manufacturing process, the evaluation primarily focuses on changes in materials, welding processes, heat treatment, rod handling, rod insertion into the skeleton, component cleaning, component inspection, core manufacturing / handling / loading, or batch assembly processes.

[0116] Specifically, the assessment of the nuclear fuel construction phase of the nuclear reactor can be carried out with reference to Table 1 below.

[0117] Table 1

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] Specifically, in this embodiment of the invention, the nuclear fuel operation phase mainly involves monitoring the nuclear fuel operation process. By monitoring the nuclear fuel during operation, it is ensured that there is sufficient margin in the nuclear fuel and that the nuclear fuel is not damaged during operation.

[0125] Optionally, in this embodiment of the invention, evaluating the nuclear fuel operation phase of the nuclear reactor includes: evaluating the operation monitoring of the nuclear reactor; evaluating the operation environment monitoring of the nuclear reactor; and evaluating the core design and operation strategy monitoring of the nuclear reactor.

[0126] Specifically, the assessment of the operation monitoring of the nuclear reactor nuclear fuel includes: obtaining core data from routine or overhaul physical tests of the nuclear fuel; and conducting an assessment based on the core data from the routine or overhaul physical tests of the nuclear fuel.

[0127] Optional core data for routine or overhaul physics tests of nuclear fuel include: average power of components, quadrant power tilt, hot spot factor, enthalpy rise factor, radial peak factor, and critical boron concentration.

[0128] Specifically, nuclear fuel operation monitoring and assessment mainly involves analyzing and judging whether changes have occurred in the nuclear fuel by obtaining the core count from routine or overhaul physical tests.

[0129] Nuclear fuel operation monitoring and evaluation involves conducting specific monitoring (such as reactor physics tests), comparing the results of these tests with standards or previous data to analyze margin and performance changes and conduct specific margin assessments. In other words, it assesses the integrity of the nuclear fuel based on whether its operating parameters in the reactor core have changed. For example, if anomalies are found in sensitive parameters such as core power or quadrant power tilt, the operating conditions are re-established, and further specific assessments are conducted.

[0130] The components include: Average Power Assigned (MAP), which primarily assesses the radial power variation of each fuel assembly in the core; Quadrant Power Tilt (DA), which is the deviation between the average power of each quadrant and the average power of the four quadrants, based on a dimensionless value determined by RPN channel measurements; Hotspot Factor (QT(Z)), which primarily assesses the variation in fuel rod dimensions (length, diameter, or wall thickness); Enthalpy Rise (FTΔH), which is the ratio of the maximum enthalpy rise within the flow channel to the core average enthalpy rise; and Radial Peak Factor F. XY On a plane at height Z, the radial peak factor is the ratio of the maximum line power density to the average line power density in that plane. Critical boron concentration CB 临界 In a reactor using soluble boron control, the boron concentration that allows the reactor to reach a critical state when all control rods are removed from the core is used.

[0131] The parameters of nuclear fuel operation monitoring serve as baseline performance data, which are compared with design or operational standards; differences represent margins. When margins decrease, qualitative nuclear fuel (non-destructive) assessments using non-universal nuclear fuel should be considered. It is also crucial to note that the inspection techniques and analytical methods used to process the parameters of measured fuel operation monitoring may change with inspection activities. Therefore, when comparing data from different inspection activities, data evaluation should consider the differences in inspection and analytical techniques to better assess reactor core system deviations and uncertainties.

[0132] Specifically, monitoring of nuclear fuel operations can be assessed with reference to Table 2.

[0133] Table 2

[0134]

[0135]

[0136] In this embodiment of the invention, the assessment of the operating environment monitoring of the nuclear reactor fuel includes: obtaining key fuel performance characteristic parameters of the primary loop water chemistry; and conducting an assessment based on the key fuel performance characteristic parameters of the primary loop water chemistry.

[0137] Specifically, the monitoring and assessment of the nuclear fuel operating environment mainly involves monitoring the water chemistry of the nuclear fuel. The goal of water chemistry monitoring is to assess changes in trends of key fuel performance characteristic parameters in the primary loop water chemistry. These changes include modifying or developing new strategies (such as increasing hydrogen or zinc injection) to provide additional stress corrosion cracking margins for primary loop components or reducing dosages, and include the use of other additives, such as increasing pH levels, affecting corrosion product (scaling) source terms, scale redistribution within the primary loop, scale deposition on fuel, and corrosion products of fuel component parameters.

[0138] During nuclear reactor operation, the corrosion associated with the fuel cladding intensifies with the increase in the length of the operating cycle, and the risk of fuel cladding failure also increases. Due to the high reactor load, and due to the nonlinear kinetics of cladding corrosion, the less protective oxides are present on the cladding surface, the stronger the corrosion will be on the high burnup fuel cladding when there are large differences in corrosion thickness.

[0139] The environmental monitoring data for nuclear fuel operation were examined and evaluated according to Table 3. If the evaluation concluded that significant changes in various water chemistry parameters could pose potential risks, a qualitative assessment of non-universal nuclear fuel was conducted on high-load, low- to medium-burnup fuel assemblies.

[0140] Table 3

[0141]

[0142] In this embodiment of the invention, the evaluation of the core design and operation strategy of the nuclear reactor fuel includes: obtaining key fuel performance parameters of the core design and operation strategy of the nuclear reactor fuel; and evaluating based on the key fuel performance parameters of the core design and operation strategy.

[0143] Optionally, in this embodiment of the invention, the key fuel performance parameters of the core design and operation strategy include: cycle strategy, burnup, core flow rate, coolant temperature, power boost, peak factor, and operation strategy.

[0144] Nuclear fuel core design and operation strategy monitoring and evaluation involves assessing key fuel performance parameters following changes in power plant operation strategies or core design. Significant changes in nuclear fuel core design and operation strategies can affect fuel cladding fouling, cladding corrosion, and cladding surface growth. If key fuel performance parameters in the core design and operation strategy change significantly, non-universal nuclear fuel qualitative analysis is conducted.

[0145] Table 4 provides guidance on various parameter changes in core design and operation strategies to assess the impact on nuclear fuel margins.

[0146] Table 4

[0147]

[0148]

[0149]

[0150]

[0151] In this embodiment of the invention, the post-unloading stage mainly involves conducting corresponding inspections and assessments of the nuclear fuel after one cycle of operation (such as assessing the low-power operation of the nuclear fuel during one cycle, and whether daily load tracking has been performed). Monitoring the nuclear fuel during the post-unloading stage ensures that there is sufficient reserve of nuclear fuel, guaranteeing that the nuclear fuel will not be damaged in the next cycle.

[0152] Optionally, in this embodiment of the invention, the evaluation of the post-nuclear fuel unloading stage of the nuclear reactor includes: evaluating the nuclear fuel baseline detection; evaluating the monitoring of nuclear fuel anomalies; and evaluating the monitoring of other nuclear fuel events.

[0153] The assessment of nuclear fuel baseline detection includes: acquiring events that affect the nuclear fuel during its operating cycle; acquiring parameters that adversely affect the reliability of the nuclear fuel; acquiring overall abnormal events and parameters during the nuclear fuel operating cycle; and conducting an assessment based on the events affecting the nuclear fuel, the parameters that adversely affect the reliability of the nuclear fuel, and the overall abnormal events and parameters during the nuclear fuel operating cycle.

[0154] Specifically, baseline testing and assessment of nuclear fuel can be conducted with reference to Table 5.

[0155] Table 5

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162] In this embodiment of the invention, the objective of nuclear fuel anomaly monitoring and assessment is to evaluate significant changes in key fuel performance parameters caused by abnormal (unplanned) reactor operating conditions and events. (For example, abnormal reactor operating conditions and events may adversely affect fuel component corrosion / scaling. Primary coolant chemical shift, i.e., axial offset anomaly (AOA), may lead to accelerated cladding corrosion and fuel performance-related fuel loading and unloading problems (such as FAD).)

[0163] Following these significant anomalies, an assessment must be conducted to determine the necessity of inspections to evaluate the impact on nuclear fuel reserves. If the assessment determines that inspections are necessary, specific inspections for these events should be subject to non-general nuclear fuel qualitative assessments. Given the wide variation in potential operational anomalies, a comprehensive analysis is required to determine whether other aspects of nuclear fuel inspections are necessary.

[0164] Optionally, in this embodiment of the invention, the assessment of monitoring anomalies in nuclear fuel includes: acquiring the nuclear fuel anomaly data; and conducting anomaly monitoring assessment based on the nuclear fuel anomaly data.

[0165] The data on nuclear fuel anomalies includes: axial offset data, data on previous cycle rods not being fully inserted, data on previous cycle fuel loading and unloading problems, data on component structural problems, and data on transportation problems.

[0166] Specifically, the monitoring of abnormal nuclear fuel conditions can be assessed with reference to Table 6.

[0167] Table 6

[0168]

[0169]

[0170] Specifically, in this embodiment of the invention, the objective of the monitoring and assessment of other nuclear fuel events is to ensure the proper handling of other changes that may adversely affect the performance and reliability of nuclear fuel. Examples include modifications to power plants that affect nuclear fuel integrity. This includes replacing major components of the primary loop (such as steam generators or coolant pumps), and the replacement components should be able to alter water corrosion products or flow rates. Modifications also include alterations to the decontamination system that may significantly increase the risk to fuel integrity.

[0171] Optionally, in this embodiment of the invention, the assessment of monitoring other nuclear fuel events includes: acquiring data on other nuclear fuel events; and conducting an assessment of monitoring other events based on the data on other nuclear fuel events.

[0172] The other nuclear fuel event data includes: power plant modification data, power plant anomaly data, and reactor water purification change data.

[0173] Specifically, monitoring of other nuclear fuel incidents can be assessed with reference to Table 7.

[0174] Table 7

[0175]

[0176]

[0177] Step S102: Based on the changes in the nuclear fuel properties of the general nuclear fuel, determine whether a non-general nuclear fuel assessment is required.

[0178] Specifically, after obtaining the classification of changes in the nuclear fuel properties of universal nuclear fuel, this classification is compared with a reference value or range. If the classification of changes exceeds the reference value or range, it indicates a significant change; otherwise, it indicates no significant change. When the classification of changes is significant, a non-universal nuclear fuel (non-damaged fuel) assessment is required; when the classification of changes is not significant, a non-universal nuclear fuel assessment is not required.

[0179] Step S103: If so, perform a non-universal nuclear fuel assessment on the nuclear reactor fuel.

[0180] Step S104: If not, check the document records and nuclear fuel performance margin records.

[0181] Furthermore, in this embodiment of the invention, the assessment of non-universal nuclear fuel for the nuclear reactor includes: assessing the internal margin of the nuclear reactor nuclear fuel cladding; and assessing the external margin of the nuclear reactor nuclear fuel cladding.

[0182] Specifically, the internal margin assessment of nuclear fuel cladding mainly focuses on nuclear fuel damage caused by PCI (fuel pellet-cladding interaction) effects.

[0183] Optionally, in this embodiment of the invention, the assessment of the internal margin of the nuclear reactor nuclear fuel cladding includes: obtaining parameters of the interaction effect between the fuel core and the cladding; and assessing the internal margin of the nuclear reactor nuclear fuel cladding based on the parameters of the interaction effect between the fuel core and the cladding.

[0184] The parameters of the interaction effect between the fuel core and the cladding include: core design parameters, power operation parameters, and fuel rod design parameters.

[0185] Specifically, in this embodiment of the invention, the core design parameters include: peak node power, node ignition loss, power control of ΔI axial power, power control rods, cycle period, long-term low power, operation, average core power, and loading mode.

[0186] The power operation parameters include: power threshold, power rise rate, control rod lifting rate, constant power duration, and axial power offset control.

[0187] The fuel rod design parameters include: cladding material, pellet thermal creep, cladding thermal creep, cladding irradiation creep, cladding thickness, pellet-cladding gap, fuel rod internal pressure, pellet defects, and pellet density.

[0188] Based on the above parameters, the present invention can evaluate the internal margin of nuclear fuel cladding, as detailed in Table 8.

[0189] Table 8

[0190]

[0191]

[0192]

[0193]

[0194] Optionally, in this embodiment of the invention, the assessment of the external margin of the nuclear reactor nuclear fuel cladding includes: assessing the micro-vibration wear of the grid-fuel rods; assessing corrosion or scaling; and assessing the deformation of the fuel assembly.

[0195] Specifically, GTRF (Grid-Fuel Rod Vibration-Resistant Wear) is a type of nuclear fuel damage. During core operation, nuclear fuel may be damaged (i.e., collapse, deformation, etc.) when positioning grid springs or baffles, affecting the contact between the grid and fuel rods. Under flow-induced vibration (FIV) conditions, reduced load can cause fuel rod movement (relative to grid functional components), leading to GTRF. Alternatively, when fuel rods are reinstalled into the grid, contact with fuel rod end plugs can deform the mixing blades, reducing the clearance between them; vibration of the fuel rods can also cause GTRF.

[0196] Based on the principle of GTRF generation, this invention evaluates grid-fuel rod micro-vibration wear in the following manner: acquiring recent event data, risk assessment data, core design and operation strategy data, and fuel design data of nuclear fuel; and evaluating grid-fuel rod micro-vibration wear based on the aforementioned data.

[0197] For specific details, please refer to Table 9 for evaluation.

[0198] Table 9

[0199]

[0200]

[0201]

[0202] Specifically, corrosion or scaling refers to the chemical reaction that occurs in the nuclear fuel cladding, leading to thinning of the cladding and the formation and accumulation of chemical reaction products on its surface. This causes an increase in the temperature of the outer surface of the cladding, thereby accelerating corrosion and causing failure. Recent studies have shown that corrosion and scaling of the nuclear fuel cladding can cause abnormal axial power in the reactor core, decreased heat transfer performance, and in severe cases, damage to the cladding.

[0203] Nuclear fuel assemblies undergo heat transfer in a boron-containing coolant. As burnup progresses, slight corrosion inevitably occurs on the cladding surface. This corrosion affects heat transfer, leading to the formation of tiny steam bubbles on the cladding surface. Corrosion particles and colloidal corrosion products in the core circuit are trapped at the steam-coolant interface. These colloidal particles then migrate towards the heated cladding surface. When the particles are close enough, they form deposits due to van der Waals forces. At the particle deposition site, steam bubbles rapidly grow and disappear, while deposits gradually accumulate, increasing the scale thickness. This scale further impairs the cladding's heat transfer, and surface boiling transforms into core boiling, ultimately leading to cladding failure.

[0204] Based on this principle, the corrosion or scaling assessment described in this invention is performed in the following manner: obtaining recent event information, water chemistry information, risk calculation information, core information, and design and operation strategy information of the cladding corrosion or structure; and assessing the corrosion or scaling based on the aforementioned information.

[0205] For specific details, please refer to Table 10 for an assessment of corrosion or scaling.

[0206] Table 10

[0207]

[0208]

[0209] Table 10 lists these questions, including assessments of known parameters affecting corrosion or scaling loads, and threshold standards exceeding any given parameter. For example, one question asks, "The maximum predicted scale thickness for cycle N is greater than 50 micrometers; or 12.5 micrometers thicker than the predicted (measured) scale thickness for cycle N-1." A "yes" answer does not necessarily mean the fuel will break down due to corrosion or scaling, but it does indicate that the margin for nuclear fuel breakdown may be smaller due to exceeding that threshold. Therefore, a detailed assessment should be conducted to determine if sufficient inspection data is available to determine the margin, or whether a targeted fuel inspection is necessary.

[0210] Specifically, in this embodiment of the invention, FAD (Fuel Assembly Deformation), while not directly manifesting as nuclear fuel damage, can lead to damage to the fuel assembly grid. Damaged grids can cause GTRF (Ground Surface Refrigerant Failure) due to loss of fuel rod support, or fuel damage due to debris generated from grid breakage. Grid damage caused by FAD affects refueling and reloading operations. Furthermore, due to fuel assembly deformation, FAD also significantly impacts core reloading time.

[0211] Therefore, embodiments of the present invention evaluate the deformation of the fuel assembly in the following manner: obtaining the deformation properties of the fuel assembly; determining deformation parameters affecting the fuel assembly based on the deformation properties; and evaluating the deformation of the fuel assembly based on the deformation parameters affecting the fuel assembly.

[0212] Table 11

[0213]

[0214] Optionally, referring to the properties in Table 11, embodiments of the present invention may use visual methods (such as inspection by camera) or direct contact methods to assess deformation.

[0215] For details, please refer to Table 12 for assessment of fuel assembly deformation.

[0216] Table 12

[0217]

[0218]

[0219]

[0220] Furthermore, in this embodiment of the invention, the non-universal nuclear fuel assessment of the nuclear reactor fuel further includes: obtaining the nuclear fuel performance margin of the nuclear reactor fuel; and conducting an assessment based on the nuclear fuel performance margin.

[0221] In some embodiments, the evaluation based on the nuclear fuel performance margin includes: comparing the nuclear fuel performance margin with a reference threshold; and evaluating based on the comparison result of the nuclear fuel performance margin and the reference threshold.

[0222] Optionally, in this embodiment of the invention, the reference threshold includes a high threshold and a low threshold.

[0223] The evaluation based on the comparison between the nuclear fuel performance margin and the reference threshold includes: if the nuclear fuel performance margin is greater than or equal to the high threshold, the nuclear fuel performance is determined to be normal; if the nuclear fuel performance margin is less than or equal to the low threshold, the nuclear fuel performance is determined to be low.

[0224] Furthermore, the nuclear reactor nuclear fuel reliability assessment method also includes: if the nuclear fuel performance is determined to be low, then determining whether the nuclear fuel performance is within a preset range; if the nuclear fuel performance is within the preset range, then determining that the nuclear fuel meets the reliability integrity condition; if the nuclear fuel performance is not within the preset range, then determining that the nuclear fuel has low reliability.

[0225] Furthermore, the nuclear reactor nuclear fuel reliability assessment method also includes: if the nuclear fuel performance is normal, then the nuclear fuel is subjected to normal or standard core design / refueling; if the nuclear fuel reliability is low, then the nuclear fuel is not subjected to normal or standard core design / refueling.

[0226] The nuclear reactor nuclear fuel reliability assessment method of this invention can assess the probability of future damage to non-damaged fuel after it has been running in the reactor, and quickly assess the causes of damage to damaged fuel and determine the fuel damage margin.

[0227] refer to Figure 2This invention provides a nuclear reactor nuclear fuel reliability assessment system. This system can be used to implement the nuclear reactor nuclear fuel reliability assessment method disclosed in the embodiments of this invention.

[0228] Specifically, such as Figure 2 As shown, the nuclear reactor nuclear fuel reliability assessment system includes:

[0229] The general assessment unit 201 is used to perform a general nuclear fuel assessment on the nuclear reactor fuel and obtain the classification of changes in the nuclear fuel properties of the general nuclear fuel.

[0230] The judgment unit 202 is used to classify and determine whether a non-universal nuclear fuel assessment is required based on the changes in the nuclear fuel properties of the universal nuclear fuel.

[0231] Non-Universal Evaluation Unit 203 is used to evaluate non-universal nuclear fuel in nuclear reactors.

[0232] Recording unit 204 is used to check document records and nuclear fuel performance margin records when non-universal nuclear fuel assessment is not required.

[0233] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0234] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0235] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0236] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They do not limit the scope of protection of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for nuclear reactor nuclear fuel reliability assessment, characterized by, Includes the following steps: A universal nuclear fuel assessment is conducted on the nuclear reactor fuel to obtain a classification of changes in the nuclear fuel properties of the universal nuclear fuel; The general-purpose nuclear fuel is a non-destructible fuel; The general nuclear fuel assessment of the nuclear reactor fuel, and the classification of changes in the nuclear fuel properties of the general nuclear fuel, include: An evaluation of the nuclear fuel construction phase of the nuclear reactor nuclear fuel is conducted; the evaluation of the nuclear fuel construction phase of the nuclear reactor nuclear fuel includes: obtaining parameters of the design and construction process of the nuclear fuel; and conducting an evaluation based on the parameters of the design and construction process of the nuclear fuel. The parameters for the design and construction process of the nuclear fuel include: fuel pellets, absorber, fuel rods, cladding, end plugs, spring devices, filling gas, grid, guide sleeves, instrument tubes, upper tube seat, lower tube seat, assembly compression springs, assembly design and manufacturing processes; The evaluation of the nuclear reactor nuclear fuel operation phase includes: evaluating the operation monitoring of the nuclear reactor nuclear fuel; evaluating the operation environment monitoring of the nuclear reactor nuclear fuel; and evaluating the core design and operation strategy monitoring of the nuclear reactor nuclear fuel. The evaluation of the operation monitoring of the nuclear reactor nuclear fuel includes: analyzing and judging whether the nuclear fuel has changed through core data from routine or overhaul physical tests to assess fuel integrity. The evaluation of the operation environment monitoring of the nuclear reactor nuclear fuel includes: obtaining key fuel performance characteristic parameters of the primary circuit water chemistry; and evaluating based on these key fuel performance characteristic parameters, including: assessing changes in the trends of key fuel performance characteristic parameters in the primary circuit water chemistry, including: modifying or developing strategies to provide additional stress corrosion cracking margins or reduce dosages for primary circuit components, and using other additives. The evaluation of the core design and operation strategy of the nuclear reactor fuel includes: obtaining key fuel performance parameters of the core design and operation strategy of the nuclear reactor fuel; and evaluating the core design and operation strategy based on the key fuel performance parameters. The core data for routine or overhaul physical tests of the nuclear fuel include: average power of the assembly, quadrant power tilt, hot spot factor, enthalpy rise factor, radial peak factor, and critical boron concentration. The key fuel performance parameters of the core design and operation strategy include: cycle period strategy, burnup, core flow rate, coolant temperature, power boost, peak factor, and operation strategy. An assessment is conducted on the post-discharge phase of the nuclear reactor nuclear fuel; the assessment includes: an assessment of nuclear fuel baseline detection; an assessment of nuclear fuel anomaly monitoring; and an assessment of other nuclear fuel events monitoring. The assessment of nuclear fuel baseline detection includes: acquiring events that affect the nuclear fuel during its operating cycle; acquiring parameters that adversely affect nuclear fuel reliability; acquiring overall abnormal events and parameters during the nuclear fuel operating cycle; and conducting an assessment based on the events affecting the nuclear fuel, the parameters that adversely affect nuclear fuel reliability, and the overall abnormal events and parameters during the nuclear fuel operating cycle. The assessment of nuclear fuel anomaly monitoring includes: acquiring nuclear fuel anomaly data; and conducting anomaly monitoring assessment based on the nuclear fuel anomaly data. The events that affect nuclear fuel are those that affect the state of nuclear fuel during the operating cycle; The parameters that cause adverse effects are those that affect the reliability of nuclear fuel; The overall abnormal events and parameters refer to all events and parameters that have changed relative to the AFA3G standard values; The nuclear fuel anomaly data includes: axial offset data, data on previous cycle rods not being fully inserted, data on previous cycle fuel loading and unloading problems, component structure problem data, and transportation problem data. The assessment of monitoring other nuclear fuel events includes: acquiring data on other nuclear fuel events; and conducting monitoring and assessment of other events based on the data on other nuclear fuel events; the data on other nuclear fuel events includes: power plant modification data, power plant anomaly data, and reactor water purification change data. Whether a non-universal nuclear fuel assessment is needed is determined based on the classification of changes in the nuclear fuel properties of the general nuclear fuel. If so, a non-universal nuclear fuel assessment is conducted on the nuclear reactor fuel; the non-universal nuclear fuel assessment includes: The internal margin of the nuclear reactor nuclear fuel cladding is assessed; the assessment of the internal margin of the nuclear reactor nuclear fuel cladding includes: obtaining the interaction effect parameters between the fuel core and the cladding; and assessing the internal margin of the nuclear reactor nuclear fuel cladding based on the interaction effect parameters between the fuel core and the cladding. The assessment of the external margin of the nuclear reactor nuclear fuel cladding includes: assessing the micro-vibration wear of the grid-fuel rods; assessing corrosion or scaling; and assessing deformation of the fuel assemblies. If not, check the documentation and nuclear fuel performance margin records.

2. The nuclear reactor core fuel reliability assessment method of Claim 1, wherein, The parameters of the interaction effect between the fuel core and the cladding include: Core design parameters, power operation parameters, and fuel rod design parameters.

3. The nuclear reactor core fuel reliability assessment method of claim 2, wherein, The core design parameters include: peak node power, node ignition burnout, power control of ΔI axial power, power control rods, cycle period, long-term low power, operation, average core power, and loading mode. The power operation parameters include: power threshold, power rise rate, control rod lifting rate, constant power duration, and axial power offset control. The fuel rod design parameters include: cladding material, pellet thermal creep, cladding thermal creep, cladding irradiation creep, cladding thickness, pellet-cladding gap, fuel rod internal pressure, pellet defects, and pellet density.

4. The nuclear reactor core fuel reliability assessment method of claim 1, wherein, The assessment of micro-vibration wear on the grid-fuel rod includes: To obtain recent event data, risk assessment data, core design and operation strategy data, and fuel design data for nuclear fuel; The micro-vibration wear of the grid-fuel rods is assessed based on recent event data, risk assessment data, core design and operation strategy data, and fuel design data.

5. The method for assessing the reliability of nuclear reactor fuel according to claim 4, characterized in that, The assessment of corrosion or scaling includes: Obtain recent event information on cladding corrosion or structure, water chemistry information, risk calculation information, core information, and design and operation strategy information; The corrosion or scaling is assessed based on recent event information, water chemistry information, risk calculation information, core information, and design and operation strategy information of the cladding corrosion or structure.

6. The method for assessing the reliability of nuclear reactor fuel according to claim 4, characterized in that, The assessment of fuel assembly deformation includes: Obtain the deformation properties of the fuel assembly; The deformation parameters affecting the fuel assembly are determined based on the deformation properties of the fuel assembly. The deformation of the fuel assembly is evaluated based on the deformation parameters that affect the fuel assembly.

7. The method for assessing the reliability of nuclear reactor fuel according to claim 1, characterized in that, The assessment of non-universal nuclear fuel for nuclear reactors also includes: To obtain the nuclear fuel performance margin of the nuclear reactor fuel; The assessment is based on the aforementioned nuclear fuel performance margin.

8. The method for assessing the reliability of nuclear reactor fuel according to claim 7, characterized in that, The assessment based on the nuclear fuel performance margin includes: The nuclear fuel performance margin is compared with a reference threshold. The evaluation is based on the comparison between the nuclear fuel performance margin and the reference threshold.

9. The method for assessing the reliability of nuclear reactor fuel according to claim 8, characterized in that, The reference thresholds include: a high threshold and a low threshold; The evaluation based on the comparison between the nuclear fuel performance margin and the reference threshold includes: If the nuclear fuel performance margin is greater than or equal to the high threshold, then the nuclear fuel performance is determined to be normal. If the nuclear fuel performance margin is less than or equal to the low threshold, the nuclear fuel performance is determined to be low.

10. The method for assessing the reliability of nuclear reactor fuel according to claim 9, characterized in that, The method further includes: If the nuclear fuel performance is determined to be low, then determine whether the nuclear fuel performance is within a preset range; If the performance of the nuclear fuel is within the preset range, then the nuclear fuel is determined to meet the reliability integrity condition; If the performance of the nuclear fuel is not within the preset range, the nuclear fuel is determined to have low reliability.

11. The method for assessing the reliability of nuclear reactor fuel according to claim 10, characterized in that, The method further includes: If the nuclear fuel performance is normal, then the nuclear fuel will be designed or refueled in a normal or standard reactor core. If the nuclear fuel has low reliability, then the nuclear fuel will not be subjected to normal or standard core design / refueling.

12. A nuclear reactor nuclear fuel reliability assessment system, characterized in that, include: A universal assessment unit is used to perform universal nuclear fuel assessment on nuclear reactor nuclear fuel and obtain the classification of changes in the nuclear fuel properties of the universal nuclear fuel; The general-purpose nuclear fuel is a non-destructible fuel; The general nuclear fuel assessment of the nuclear reactor fuel, and the classification of changes in the nuclear fuel properties of the general nuclear fuel, include: An evaluation of the nuclear fuel construction phase of the nuclear reactor nuclear fuel is conducted; the evaluation of the nuclear fuel construction phase of the nuclear reactor nuclear fuel includes: obtaining parameters of the design and construction process of the nuclear fuel; and conducting an evaluation based on the parameters of the design and construction process of the nuclear fuel. The parameters for the design and construction process of the nuclear fuel include: fuel pellets, absorber, fuel rods, cladding, end plugs, spring devices, filling gas, grid, guide sleeves, instrument tubes, upper tube seat, lower tube seat, assembly compression springs, assembly design and manufacturing processes; The evaluation of the nuclear reactor nuclear fuel operation phase includes: evaluating the operation monitoring of the nuclear reactor nuclear fuel; evaluating the operation environment monitoring of the nuclear reactor nuclear fuel; and evaluating the core design and operation strategy monitoring of the nuclear reactor nuclear fuel. The evaluation of the operation monitoring of the nuclear reactor nuclear fuel includes: analyzing and judging whether the nuclear fuel has changed through core data from routine or overhaul physical tests to assess fuel integrity. The evaluation of the operation environment monitoring of the nuclear reactor nuclear fuel includes: obtaining key fuel performance characteristic parameters of the primary circuit water chemistry; and evaluating based on these key fuel performance characteristic parameters, including: assessing changes in the trends of key fuel performance characteristic parameters in the primary circuit water chemistry, including: modifying or developing strategies to provide additional stress corrosion cracking margins or reduce dosages for primary circuit components, and using other additives. The evaluation of the core design and operation strategy of the nuclear reactor fuel includes: obtaining key fuel performance parameters of the core design and operation strategy of the nuclear reactor fuel; and evaluating the core design and operation strategy based on the key fuel performance parameters. The core data for routine or overhaul physical tests of the nuclear fuel include: average power of the assembly, quadrant power tilt, hot spot factor, enthalpy rise factor, radial peak factor, and critical boron concentration. The key fuel performance parameters of the core design and operation strategy include: cycle period strategy, burnup, core flow rate, coolant temperature, power boost, peak factor, and operation strategy. An assessment is conducted on the post-discharge phase of the nuclear reactor nuclear fuel; the assessment includes: an assessment of nuclear fuel baseline detection; an assessment of nuclear fuel anomaly monitoring; and an assessment of other nuclear fuel events monitoring. The assessment of nuclear fuel baseline detection includes: acquiring events that affect the nuclear fuel during its operating cycle; acquiring parameters that adversely affect nuclear fuel reliability; acquiring overall abnormal events and parameters during the nuclear fuel operating cycle; and conducting an assessment based on the events affecting the nuclear fuel, the parameters that adversely affect nuclear fuel reliability, and the overall abnormal events and parameters during the nuclear fuel operating cycle. The assessment of nuclear fuel anomaly monitoring includes: acquiring nuclear fuel anomaly data; and conducting anomaly monitoring assessment based on the nuclear fuel anomaly data. The events that affect nuclear fuel are those that affect the state of nuclear fuel during the operating cycle; The parameters that cause adverse effects are those that affect the reliability of nuclear fuel; The overall abnormal events and parameters refer to all events and parameters that have changed relative to the AFA3G standard values; The nuclear fuel anomaly data includes: axial offset data, data on previous cycle rods not being fully inserted, data on previous cycle fuel loading and unloading problems, component structure problem data, and transportation problem data. The assessment of monitoring other nuclear fuel events includes: acquiring data on other nuclear fuel events; and conducting monitoring and assessment of other events based on the data on other nuclear fuel events; the data on other nuclear fuel events includes: power plant modification data, power plant anomaly data, and reactor water purification change data. The judgment unit is used to classify and determine whether a non-universal nuclear fuel assessment is required based on the changes in the nuclear fuel properties of the universal nuclear fuel. A non-universal evaluation unit is used to perform non-universal nuclear fuel evaluation on nuclear reactor fuel; the non-universal nuclear fuel evaluation on nuclear reactor fuel includes: The internal margin of the nuclear reactor nuclear fuel cladding is assessed; the assessment of the internal margin of the nuclear reactor nuclear fuel cladding includes: obtaining the interaction effect parameters between the fuel core and the cladding; and assessing the internal margin of the nuclear reactor nuclear fuel cladding based on the interaction effect parameters between the fuel core and the cladding. The assessment of the external margin of the nuclear reactor nuclear fuel cladding includes: assessing the micro-vibration wear of the grid-fuel rods; assessing corrosion or scaling; and assessing deformation of the fuel assemblies. The recording unit is used to check the documentation and nuclear fuel performance margin records when non-universal nuclear fuel assessments are not required.

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