Method and device for predicting peak of fissile product of pressurized water reactor nuclear power plant

Abstract

The application discloses a method and device for predicting a peak value of a fissile product of a pressurized water reactor nuclear power plant. The method comprises: obtaining a first nuclide concentration of each fissile product in a primary coolant and an operating parameter at a current time in an operating interval of the pressurized water reactor nuclear power plant; determining a fuel damage parameter corresponding to the first nuclide concentration and the operating parameter based on a preset fuel cladding rupture diagnosis algorithm; determining a second nuclide concentration prediction value of each fissile product in the primary coolant at the end of the current operating interval based on a first prediction model, the operating parameter and the fuel damage parameter; and determining a third nuclide concentration prediction peak value of each fissile product in the primary coolant in a shutdown interval based on a second prediction model, the second nuclide concentration prediction value, the operating parameter and the fuel damage parameter. The method can realize the prediction of the nuclide concentration peak value of the fissile product in the shutdown condition, and then the shutdown strategy can be formulated or modified according to the predicted concentration peak value, so as to guarantee the safety and reliability of the shutdown.

Description

Technical Field

[0001] This application belongs to the field of nuclear power technology, and in particular relates to a method and apparatus for predicting the peak value of fission products in a pressurized water reactor nuclear power plant. Background Technology

[0002] During the operation of a pressurized water reactor nuclear power plant, the primary coolant in the primary loop system cools the nuclear fuel assemblies and transfers heat from the nuclear fuel assemblies to the secondary loop system, thereby generating high-temperature and high-pressure steam in the secondary loop system to drive the turbine to generate electricity.

[0003] The primary coolant is in direct contact with the nuclear fuel assemblies. When the fuel cladding is intact, the primary coolant contains a small amount of fission product nuclides due to the radioactive uranium fission contamination on the fuel surface. When the fuel cladding is damaged, the fission product nuclides are released into the primary coolant through the breach, resulting in a significant increase in the concentration of fission product nuclides in the primary coolant.

[0004] When a pressurized water reactor nuclear power plant is shut down, the fission reaction rate inside the nuclear fuel assemblies gradually decreases to near zero. At this time, the internal pressure and temperature of the nuclear fuel assemblies change drastically, causing a sharp increase in the rate at which fission product nuclides are released from the assemblies. During this release process, there is a peak in the concentration of fission product nuclides in the primary coolant. The magnitude of this peak directly affects the shutdown time and downstream radiation protection, thus impacting the economics and safety of the unit. Summary of the Invention

[0005] This application provides a method and apparatus for predicting the peak value of fission products in a pressurized water reactor nuclear power plant, which can predict the peak value of fission product nuclide concentration in the primary coolant after the pressurized water reactor nuclear power plant is shut down.

[0006] In a first aspect, embodiments of this application provide a method for predicting the peak fission products of a pressurized water reactor nuclear power plant, the method comprising: Within the operating range of a pressurized water reactor nuclear power plant, obtain the concentration of the first nuclide of each fission product and the operating parameters in the primary coolant at the current moment; Based on a preset fuel cladding damage diagnosis algorithm, the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters are determined; Based on the first prediction model, the operating parameters, and the fuel damage parameters, the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval are determined. Based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters, the predicted peak values ​​of the third nuclide concentrations of each fission product in the primary coolant within the shutdown interval are determined.

[0007] In one embodiment of this application, after determining the predicted peak values ​​of the third nuclide concentrations of each fission product in the primary coolant during the shutdown interval based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters, the method further includes: Within the operating range of a pressurized water reactor nuclear power plant, the concentration of the first nuclide of each fission product in the primary coolant is updated based on a preset measurement interval. The predicted values ​​of the second nuclide concentration and the predicted peak value of the third nuclide concentration are corrected based on the updated first nuclide concentration.

[0008] In one embodiment of this application, obtaining the concentration of the first nuclide of each fission product in the primary coolant at the current moment includes: A sample of the primary coolant at the current moment is obtained; Radioactive analysis was performed on the sampled material to obtain the concentration of the first nuclide in each fission product. Alternatively, the primary coolant at the current moment can be measured online using a preset online spectrum measurement module to obtain the first nuclide concentration of each fission product.

[0009] In one embodiment of this application, the operating parameters include: fuel loading parameters, power variation parameters, primary loop purification flow rate, primary loop purification and decontamination efficiency, and primary loop water loading volume for the current cycle process of the pressurized water reactor nuclear power plant.

[0010] In one embodiment of this application, the fuel damage parameters include the number of damaged components, the size of the rupture, and the fuel consumption range of the damaged components; The fuel cladding damage diagnosis algorithm, based on a preset algorithm, determines the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters, including: Based on the concentration of the first nuclide in the first characteristic fission product, fuel damage characteristic parameters are determined. Determine whether fuel coating damage exists based on the aforementioned fuel damage characteristic parameters; In the presence of fuel cladding defects, the number of defective components in the fuel cladding is determined based on the concentration of the first nuclide in some fission products. Based on the first nuclide concentration of each fission product, the equivalent escape rate coefficient ratio of some nuclide combinations is determined; The size of the puncture in the fuel cladding is determined based on the equivalent escape rate coefficient ratio and the number of damaged components. The burnup range of the damaged components in the fuel cladding is determined based on the concentration of the first nuclide in some fission products and the number of damaged components.

[0011] In one embodiment of this application, determining the predicted concentration values ​​of the second nuclides of each fission product in the primary coolant at the end of the current operating interval based on the first prediction model, the operating parameters, and the fuel damage parameters includes: The operating parameters, the number of damaged components, the size of the breach, and the burnup range of the damaged components are input into the first prediction model to obtain the first correspondence between each fission product in the primary coolant within the current operating range; wherein, the first correspondence is the correspondence between the predicted nuclide concentration and time. Based on the first correspondence, the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval are determined.

[0012] In one embodiment of this application, the first prediction model includes the release rate of each fission product into the primary coolant within the current operating range through broken cladding, fission of contaminated uranium, and release of corroded uranium.

[0013] In one embodiment of this application, determining the predicted peak value of the third nuclide concentration of each fission product in the primary coolant during the shutdown interval based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters includes: The operating parameters and the fuel damage parameters are input into the second prediction model to obtain the second correspondence between each fission product within the shutdown interval; wherein, the second correspondence is the correspondence between the release rate of each fission product and time. Based on the second nuclide concentration prediction value and the second correspondence of each fission product in the shutdown interval, the third nuclide concentration prediction peak value of each fission product in the primary coolant in the shutdown interval is determined.

[0014] In one embodiment of this application, the second prediction model includes the release rate of each fission product into the primary coolant through the broken cladding during a reactor shutdown transient.

[0015] In one embodiment of this application, the correction of the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the updated first nuclide concentration includes: The first correspondence is corrected based on the updated first nuclide concentrations of each fission product; The predicted values ​​of the second nuclide concentration and the predicted peak value of the third nuclide concentration are corrected based on the corrected first correspondence.

[0016] In one embodiment of this application, the step of correcting the first correspondence based on the updated first nuclide concentrations of each fission product includes: Based on the first nuclide concentrations of each fission product at previous measurement time points and the updated first nuclide concentrations of each fission product, the first correspondences of each fission product are fitted and corrected to obtain the corrected first correspondences.

[0017] In one embodiment of this application, after determining the predicted concentration values ​​of the second nuclides of each fission product in the primary coolant at the end of the current operating interval based on the first correspondence, the method further includes: Obtain the preset concentration limits for each fission product; Based on the predicted concentration values ​​of the second nuclide of each fission product and the corresponding concentration limits, it is determined whether each fission product exceeds the limit within the current operating range.

[0018] In one embodiment of this application, after determining whether each fission product exceeds the limit within the current operating range based on the predicted concentration value of the second nuclide of each fission product and the corresponding concentration limit, the method further includes: If at least one fission product exceeds the limit in the current operating range, the time node corresponding to the predicted nuclide concentration reaching the concentration limit corresponding to the target fission product is determined according to the first correspondence relationship corresponding to the target fission product; wherein, the target fission product is the fission product that exceeds the limit in the current operating range among multiple fission products.

[0019] In one embodiment of this application, after correcting the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the updated first nuclide concentration, the method further includes: After a preset prediction period, the concentration of the first nuclide of each fission product in the primary coolant and the operating parameters are reacquired, and the process returns to the step: based on a preset fuel cladding damage diagnosis algorithm, the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters are determined until the pressurized water reactor nuclear power plant is shut down.

[0020] Secondly, embodiments of this application provide a peak fission product prediction device for a pressurized water reactor nuclear power plant, the device comprising: The acquisition module is used to acquire the concentration of the first nuclide of each fission product and the operating parameters of the primary coolant in the primary loop at the current moment within the operating range of the pressurized water reactor nuclear power plant. The damage determination module is used to determine the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters based on a preset fuel cladding damage diagnosis algorithm. The first concentration prediction module is used to determine the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval based on the first prediction model, the operating parameters and the fuel damage parameters. The second concentration prediction module is used to determine the predicted peak value of the third nuclide concentration of each fission product in the primary coolant within the shutdown interval based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters.

[0021] This application provides a method and apparatus for predicting peak fission products in a pressurized water reactor (PWR) nuclear power plant. After obtaining the first nuclide concentrations of each fission product in the primary coolant and related operating parameters, the fuel cladding damage status can be determined based on fuel damage parameters obtained from a fuel cladding damage diagnosis algorithm. Based on these fuel damage parameters, the predicted values ​​of the second nuclide concentrations of each fission product at the end of the current operating interval and the predicted peak values ​​of the third nuclide concentrations of each fission product within the shutdown interval can be determined sequentially using a preset first prediction model and a second prediction model. During the shutdown preparation phase, based on the obtained predicted peak values ​​of the third nuclide concentrations of each fission product, the shutdown strategy of the PWR nuclear power plant can be formulated and modified, and corresponding protective measures can be arranged to reduce the radiation dose to relevant personnel and ensure the safety of PWR nuclear power plant shutdown maintenance. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating a method for predicting the peak fission products of a pressurized water reactor nuclear power plant provided in an embodiment of this application. Figure 2 This is another schematic diagram of the fission product peak prediction method for pressurized water reactor nuclear power plants provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the fission product peak prediction device for a pressurized water reactor nuclear power plant provided in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0024] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0025] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0026] In all specific embodiments of this application, when processing data related to user identity or characteristics, such as user information, user behavior data, user historical data, and user location information, user permission or consent is obtained first. Furthermore, the collection, use, and processing of this data comply with relevant laws, regulations, and standards. Additionally, when embodiments of this application require access to sensitive personal information, separate permission or consent from the user is obtained through pop-ups or redirects to confirmation pages. Only after obtaining the user's separate permission or consent is the necessary user-related data required for the proper functioning of these embodiments obtained.

[0027] To address the problems of existing technologies, this application provides a method and apparatus for predicting the peak fission products of pressurized water reactor nuclear power plants. The method for predicting the peak fission products of pressurized water reactor nuclear power plants provided in this application is described below.

[0028] Figure 1 A schematic flowchart of a method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to an embodiment of this application is shown. Figure 1 As shown in the embodiments of this application, the method for predicting the peak fission products of pressurized water reactor nuclear power plants, when applied to electronic devices such as servers, includes the following steps 101-104, wherein: Step 101: Within the operating range of the pressurized water reactor nuclear power plant, obtain the concentration of the first nuclide of each fission product in the primary coolant at the current moment, as well as the operating parameters.

[0029] In this embodiment, the pressurized water reactor nuclear power plant can adopt a cyclic operation mode, which includes an operating interval and a shutdown interval during a single cycle. Within the operating interval, the equipment can obtain the concentration of the first nuclide of each fission product in the primary coolant at the current moment, as well as the corresponding operating parameters during the current cycle.

[0030] During the operation of a pressurized water reactor (PWR) nuclear power plant, the fission products released from nuclear fuel assemblies into the primary coolant typically include radioactive isotopes of elements such as krypton (Kr), xenon (Xe), iodine (I), and cesium (Cs). During PWR operation, the concentration of the primary nuclide corresponding to each type of product can be obtained at specific times. Furthermore, operating parameters such as the number of nuclear fuel assemblies involved in operation, operating power, and the total mass of coolant in the primary coolant system may change in different cycles; therefore, it is also necessary to obtain the corresponding operating parameters for each cycle.

[0031] Step 102: Based on a preset fuel cladding damage diagnosis algorithm, determine the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters.

[0032] In this embodiment, after determining the concentration of the first nuclide of each fission product and the operating parameters, the fuel damage parameters of the fuel cladding can be determined based on a preset fuel cladding damage diagnosis algorithm, that is, the damage status of the fuel cladding can be obtained.

[0033] The fuel damage parameters of the aforementioned fuel cladding can be parameters such as the number of damaged components in the fuel assembly, the size of the puncture, and the burnup range of the damaged components, which are not limited here.

[0034] Step 103: Based on the first prediction model, the operating parameters, and the fuel damage parameters, determine the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval.

[0035] In this embodiment, the device has a pre-embedded first prediction model. The operating parameters of the current cycle and the fuel damage parameters obtained through the fuel cladding damage diagnosis algorithm are input into the first prediction model, which can predict the changing trends of the nuclide concentrations of various fission products in the primary coolant during the remaining time of the current operating interval. Since the operating time of the current cycle is preset, the end time of the current cycle, i.e., the end time of the current operating interval, can be determined based on the start time and operating time of the current cycle.

[0036] Based on the trend of the nuclide concentration of each fission product over time, the predicted value of the second nuclide concentration of each fission product at the end of the current operating interval can be determined.

[0037] Step 104: Based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters, determine the predicted peak value of the third nuclide concentration of each fission product in the primary coolant within the shutdown interval.

[0038] In this embodiment, the device is also pre-embedded with a second prediction model. After determining the predicted value of the second nuclide concentration of each fission product at the end of the current operating interval, the predicted value of the second nuclide concentration, the operating parameters and the fuel damage parameters can be input into the second prediction model. The predicted peak value of the third nuclide concentration of each fission product in the primary coolant during the shutdown interval can be predicted by the second prediction model.

[0039] Understandably, taking a specific fission product as an example, at the instant a pressurized water reactor nuclear power plant begins shutdown, the nuclide concentration of the fission product in the primary coolant can be considered as the second predicted nuclide concentration. Under the transient shutdown conditions, the release rate coefficient of the fission product into the primary coolant has an initial value. During shutdown, this release rate coefficient can increase exponentially, reach a peak, and then decrease exponentially again, eventually reaching a stable value. Therefore, within the shutdown period, there is a peak concentration of this fission product. The third predicted nuclide concentration peak of this fission product within the shutdown period can then be predicted using the aforementioned second prediction model.

[0040] In this embodiment, after obtaining the first nuclide concentrations of each fission product in the primary coolant and related operating parameters, the fuel cladding damage status can be determined based on the fuel damage parameters obtained from the fuel cladding damage diagnosis algorithm. Based on these fuel damage parameters, the predicted values ​​of the second nuclide concentrations of each fission product at the end of the current operating interval and the predicted peak values ​​of the third nuclide concentrations of each fission product within the shutdown interval can be determined sequentially using a preset first prediction model and a second prediction model. During the shutdown preparation phase, based on the obtained predicted peak values ​​of the third nuclide concentrations of each fission product, the shutdown strategy for the pressurized water reactor nuclear power plant can be formulated and modified, and corresponding protective measures can be arranged to reduce the radiation dose to relevant personnel and ensure the safety of the pressurized water reactor nuclear power plant during shutdown maintenance.

[0041] It should be noted that when the fuel cladding is intact, the primary coolant contains a small amount of fission product nuclides due to radioactive uranium fission contamination on the fuel surface. During shutdown, the concentration of these nuclides is low and does not affect the specific shutdown strategy. However, when the fuel cladding is damaged, fission product nuclides generated inside the cladding will be released into the primary coolant through the breach, significantly increasing the concentration of fission product nuclides in the primary coolant. In this scenario, during a pressurized water reactor shutdown, all control rods are inserted, causing a sharp drop in reactor power and reducing the fission rate inside the fuel assembly to near zero. At this point, the internal pressure and temperature of the fuel assembly change drastically, leading to a sharp increase in the release rate of fission product nuclides from the fuel assembly, resulting in a peak concentration of fission product nuclides in the primary coolant. Furthermore, the magnitude of this peak concentration directly affects the shutdown time and downstream radiation protection, thus impacting the unit's economics and safety.

[0042] Therefore, the embodiments described above in this application predict the nuclide concentration at the end of the cycle and the peak nuclide concentration under shutdown conditions based on a preset mathematical model when it is determined that the cladding of the nuclear fuel assembly has been damaged. In the above embodiments, if the fuel cladding damage diagnosis algorithm determines that the cladding is not damaged, the result of the determination that the cladding is not damaged can be directly shown to relevant personnel without the need to predict the peak concentration based on a mathematical model. Furthermore, diagnosing whether the fuel cladding is damaged first, and then predicting the trend of nuclide concentration changes and the peak nuclide concentration during the shutdown period, can better reflect the current operating history and parameter impact of the nuclear power plant.

[0043] Please refer to Figure 2 In one embodiment of this application, after step 104, the method further includes: Step 105: Within the operating range of the pressurized water reactor nuclear power plant, update the concentration of the first nuclide of each fission product in the primary coolant based on a preset measurement interval. Step 106: Correct the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the updated first nuclide concentration.

[0044] In this embodiment, within the operating range of the pressurized water reactor nuclear power plant, the first nuclide concentration of each fission product in the primary coolant can be re-acquired after each preset measurement interval, that is, the first nuclide concentration of each fission product in the primary coolant is periodically updated.

[0045] After obtaining the updated first nuclide concentration, the predicted values ​​of the second nuclide concentration and the predicted peak value of the third nuclide concentration of each fission product obtained in the previous measurement interval can be corrected based on the updated first nuclide concentration.

[0046] In one embodiment of this application, obtaining the concentration of the first nuclide of each fission product in the primary coolant at the current moment includes: A sample of the primary coolant at the current moment is obtained; Radioactive analysis was performed on the sampled material to obtain the concentration of the first nuclide in each fission product. Alternatively, the primary coolant at the current moment can be measured online using a preset online spectrum measurement module to obtain the first nuclide concentration of each fission product.

[0047] In this embodiment, the concentration of the first nuclide of each fission product in the primary coolant at the current moment can be obtained by one of the following two methods, which is not limited here.

[0048] In the first approach, the primary coolant can be sampled at the current moment to obtain a sample, and the sample can be subjected to radioactive analysis by a corresponding radiochemistry laboratory to obtain the first nuclide concentration of each fission product.

[0049] In the second approach, an online spectrum measurement module can be set up to directly measure the spectrum of the primary coolant at the current moment, thereby obtaining the concentration of the first nuclide of each fission product.

[0050] Understandably, the measurement time using the first method described above is usually longer than that using the second method. In the second method, the concentration of the first nuclide in each fission product at a single moment can be obtained through multiple measurements. For example, at a given moment, multiple data acquisitions can be performed within a certain time interval, and the collected data can be statistically averaged to obtain the final average value as the concentration of the first nuclide in each fission product.

[0051] In one embodiment of this application, the operating parameters include: fuel loading parameters, power variation parameters, primary loop purification flow rate, primary loop decontamination efficiency, and primary loop water loading volume for the current cycle process of the pressurized water reactor nuclear power plant.

[0052] In this embodiment, the operating parameters at the current moment may include the fuel loading parameters, power change parameters, primary loop decontamination flow rate, primary loop decontamination efficiency, and primary loop water load for the current cycle of the pressurized water reactor nuclear power plant. The fuel loading parameters may include the initial configuration, physical characteristics, and management indicators of each nuclear fuel assembly during this cycle; the primary loop decontamination flow rate refers to the volumetric flow rate of coolant continuously drawn from the primary loop system and returned after purification; the primary loop decontamination efficiency refers to the purification efficiency of the configured purification device for fission product nuclides in the coolant continuously drawn from the primary loop system; and the primary loop water load refers to the total mass of the primary loop coolant.

[0053] In one embodiment of this application, the fuel damage parameters include the number of damaged components, the size of the rupture, and the fuel consumption range of the damaged components; The fuel cladding damage diagnosis algorithm, based on a preset algorithm, determines the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters, including: Based on the concentration of the first nuclide in the first characteristic fission product, fuel damage characteristic parameters are determined. Determine whether fuel coating damage exists based on the aforementioned fuel damage characteristic parameters; In the presence of fuel cladding defects, the number of defective components in the fuel cladding is determined based on the concentration of the first nuclide in some fission products. Based on the first nuclide concentration of each fission product, the equivalent escape rate coefficient ratio of some nuclide combinations is determined; The size of the puncture in the fuel cladding is determined based on the equivalent escape rate coefficient ratio and the number of damaged components. The burnup range of the damaged components in the fuel cladding is determined based on the concentration of the first nuclide in some fission products and the number of damaged components.

[0054] In this embodiment, fuel damage parameters may include the number of damaged components, the size of the puncture, and the fuel consumption range of the damaged components.

[0055] After obtaining the first nuclide concentration of each fission product, a first characteristic fission product can be determined from multiple fission products. The first characteristic fission product can be a portion of all fission products that can be used to determine whether the fuel cladding is damaged. The first characteristic fission product includes some actinide nuclides.

[0056] After determining the first characteristic fission product, the fuel damage characteristic parameters required by the fuel cladding damage diagnosis algorithm can be obtained. These fuel damage characteristic parameters may include the concentration of the first nuclide of a certain first characteristic fission product, the concentration ratio of two first characteristic fission products, and the change in a certain first characteristic fission product.

[0057] Based on this fuel damage characteristic parameter, it can be determined whether the fuel cladding is damaged.

[0058] As an example, the aforementioned first characteristic fission products may include I-131, I-134, I-133, Xe-133, Xe-135, all alpha radionuclides, and Np-239, etc. The corresponding fuel damage characteristic parameters include four parts: the change in I-134; the I-131 concentration and the I-131 / I-133 concentration ratio; the Xe-133 concentration and the Xe-133 / Xe-135 concentration ratio; and whether the total alpha concentration or Np-239 concentration reaches the detection limit. By comparing the actual values ​​of the above four fuel damage characteristic parameters with pre-set reference intervals, the presence of fuel cladding damage can be determined based on the comparison results.

[0059] When damage to the fuel cladding is determined, the number of damaged components can be determined based on the concentration of the first nuclide in some fission products. For example, the number of damaged components in the fuel cladding can be diagnosed based on the concentration of the first nuclides Xe-133 and Kr-85 in the primary coolant.

[0060] Based on the first nuclide concentration of each fission product, the equivalent escape rate coefficient ratio of some nuclide combinations can be obtained. Based on this equivalent escape rate coefficient ratio and the number of damaged components obtained above, the size of the break in the fuel cladding can be further determined. For example, based on the first nuclide concentration of multiple fission products, the equivalent escape rate coefficient ratios of the following six nuclide combinations can be obtained, namely I-131 / Xe-133, I-131 / Kr-85, Cs-134 / Kr-85, Cs-137 / Kr-85, Cs-134 / Xe-133, and Cs-137 / Xe-133.

[0061] Based on the concentration of the first nuclide in some fission products and the number of broken components, the burnup range of the broken components in the fuel cladding can also be determined. For example, the burnup range of the broken components can be determined based on the Cs-134 / Cs-137 concentration ratio and the number of broken components.

[0062] In one embodiment of this application, determining the predicted concentration values ​​of the second nuclides of each fission product in the primary coolant at the end of the current operating interval based on the first prediction model, the operating parameters, and the fuel damage parameters includes: The operating parameters, the number of damaged components, the size of the breach, and the burnup range of the damaged components are input into the first prediction model to obtain the first correspondence between each fission product in the primary coolant within the current operating range; wherein, the first correspondence is the correspondence between the predicted nuclide concentration and time. Based on the first correspondence, the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval are determined.

[0063] In this embodiment, after obtaining the number of damaged components, the size of the rupture, and the burnup range of the damaged components through the above implementation method, these can be input together with the operating parameters into a preset first prediction model to obtain the first correspondence between each fission product in the primary coolant within the current operating interval output by the first prediction model. This first correspondence is the correspondence between time and the predicted value of nuclide concentration, which can be used to characterize the changing trend of the nuclide concentration of each fission product in the primary coolant during the remaining time of the current cycle.

[0064] Based on the first correspondence, after determining the end time of the current operating interval, the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end time of the current operating interval can be obtained.

[0065] As an example, the first prediction model can be constructed in the following manner.

[0066] Fission products typically include ionic fission products and suspended fission products.

[0067] For the ionic fission products, the corresponding equilibrium equation is as follows:

[0068] (Equation 1); in, The concentration of ionic nuclide i in the fission products, in units of ; The dissolution fraction of fission product i is dimensionless; The total mass of the primary coolant, in units of ; Cj(t) represents the release rate of fission products through the broken shell and the released actinide nuclides into the primary coolant, expressed in atoms / s; Cj(t) is the nuclide concentration of the precursor nucleus j (i.e., the parent nucleus) of nuclide i in the primary coolant, expressed in atoms / s. ; The decay constant for the parent nucleus or the next generation parent nucleus j decaying to produce nuclide i, expressed in units of 1 / s; The microscopic reaction cross section of precursor nuclide j to generate nuclide i via neutron capture, in units of ; The average neutron flux density in the irradiated area is expressed in units of 1000 ppm. ; It is the ratio of the time it takes for the primary fluid to flow through the flux irradiation zone to the total time it takes for the primary fluid to circulate once in one loop, and is dimensionless. The cross section of the microscopic reaction of nuclide i undergoing neutron capture is given in units of 1000 m. ; is the decay constant of nuclide i, in units of 1 / s; t is the time constant for the leakage to disappear, in units of 1 / s; D(t) is the boron dilution factor, in units of 1 / s; Mass flow rate for purification or discharge from chemical and volumetric control systems, expressed in g / s; is the decontamination factor for nuclide i, dimensionless.

[0069] For suspended fission products, we can assume that only suspended nuclides will undergo dissolution and deposition. The equilibrium equation for suspended fission products is as follows: (Equation 2); in, The concentration of suspended nuclide i in the fission products, in units of ; The dissolution fraction of fission product i is dimensionless; The total mass of the primary coolant, in units of ; Cj(t) represents the release rate of fission products through the broken shell and the released actinide nuclides into the primary coolant, expressed in atoms / s; Cj(t) is the nuclide concentration of the precursor nucleus j (i.e., the parent nucleus) of nuclide i in the primary coolant, expressed in atoms / s. ; The decay constant for the parent nucleus or the next generation parent nucleus j decaying to produce nuclide i, expressed in units of 1 / s; The microscopic reaction cross section of precursor nuclide j to generate nuclide i via neutron capture, in units of ; The average neutron flux density in the irradiated area is expressed in units of 1000 ppm. ; It is the ratio of the time it takes for the primary fluid to flow through the flux irradiation zone to the total time it takes for the primary fluid to circulate once in one loop, and is dimensionless. The cross section of the microscopic reaction of nuclide i undergoing neutron capture is given in units of 1000 m. ; is the decay constant of nuclide i, in units of 1 / s; t is the time constant for leakage disappearance, in units of 1 / s; D(t) is the boron dilution factor, in units of 1 / s; Vd is the total deposition disappearance coefficient of suspended particulate nuclides, in units of 1 / s; Mass flow rate for purification or discharge from chemical and volumetric control systems, expressed in g / s; is the decontamination factor for nuclide i, dimensionless.

[0070] In time step For example, in During the time step from time t to time t, D(t) can be considered a constant value, and is taken as D( ),exist up to time step t The two equilibrium equations mentioned above are then solved.

[0071] For the fission products in the ionic state, we can obtain: (Equation 3); in, The concentration of ionic nuclide i in the fission products; The equivalent decay constant of dissolved nuclides, expressed in units of 1 / s; The dissolution fraction of fission product i is dimensionless; The release rate is the rate at which fission products are released into the primary coolant through the broken shell and the released actinide nuclides, expressed in atoms / s. The total mass of the primary coolant, in units of Cj(t) represents the nuclide concentration of precursor nucleus j (i.e., parent nucleus) of nuclide i in the primary coolant, in units of t. ; The decay constant of nuclide i formed by the decay of the parent nucleus or the next generation parent nucleus j, expressed in units of 1000 ppm. ; The microscopic reaction cross section of precursor nuclide j to generate nuclide i via neutron capture, in units of ; The average neutron flux density in the irradiated area is expressed in units of 1000 ppm. ; It is the ratio of the time it takes for the primary fluid to flow through the flux irradiation zone to the total time it takes for the primary fluid to circulate once in one loop, and is dimensionless.

[0072] (Equation 4); in, The equivalent decay constant of the dissolved nuclide is expressed in units of 1 / s. The cross section of the microscopic reaction of nuclide i undergoing neutron capture is given in units of 1000 m. ; The average neutron flux density in the irradiated area is expressed in units of 1000 ppm. ; It is the ratio of the time it takes for the primary fluid to flow through the flux irradiation zone to the total time it takes for the primary fluid to circulate once in one loop, and is dimensionless. The time constant for the leakage to disappear, in units of D(t) is the boron dilution factor, in units of 1 / s; Mass flow rate for purification or discharge from chemical and volumetric control systems, expressed in g / s; The total mass of the primary coolant, in units of ; is the decontamination factor for nuclide i, dimensionless.

[0073] For fission products in suspension, we can obtain: (Equation 5); in, The concentration of suspended nuclide i in the fission products, in units of ; is the equivalent decay constant of particulate nuclides, in units of 1 / s; The dissolution fraction of fission product i is dimensionless; The release rate is the rate at which fission products are released into the primary coolant through the broken shell and the released actinide nuclides, expressed in atoms / s. The total mass of the primary coolant, in units of Cj(t) represents the nuclide concentration of precursor nucleus j (i.e., parent nucleus) of nuclide i in the primary coolant, in units of t. ; The decay constant for nuclide i generated from the decay of the parent nucleus or the parent nucleus j of a previous generation, in units of ; The microscopic reaction cross section of precursor nuclide j to generate nuclide i via neutron capture, in units of ; The average neutron flux density in the irradiated area is expressed in units of 1000 ppm. ; It is the ratio of the time it takes for the primary fluid to flow through the flux irradiation zone to the total time it takes for the primary fluid to circulate once in one loop, and is dimensionless.

[0074] (Formula 6); in, is the equivalent decay constant of particulate nuclides, in units of 1 / s; The cross section of the microscopic reaction of nuclide i undergoing neutron capture is given in units of 1000 m. ; The average neutron flux density in the irradiated area is expressed in units of 1000 ppm. ; It is the ratio of the time it takes for the primary fluid to flow through the flux irradiation zone to the total time it takes for the primary fluid to circulate once in one loop, and is dimensionless. The time constant for the leakage to disappear, in units of D(t) is the boron dilution factor, in units of 1 / s; Vd is the total deposition disappearance coefficient of suspended particulate nuclides, in units of ; Mass flow rate for purification or discharge from chemical and volumetric control systems, expressed in g / s; The total mass of the primary coolant, in units of ; is the decontamination factor for nuclide i, dimensionless.

[0075] The total concentration of nuclide i in the fission products can be expressed as: (Equation 7); Where Cj(t) is the total concentration of nuclide i in the fission products, in units of ; The concentration of ionic nuclide i in the fission products, in units of ; The concentration of suspended nuclide i in the fission products, in units of .

[0076] The calculation of each intermediate parameter in the above formula is as follows: = (Equation 8); in, The time constant for the leakage to disappear, in units of ; This represents the primary coolant leakage flow rate, expressed in g / s. This represents the total mass of the primary coolant, expressed in grams.

[0077] (Equation 9); in, This is the boron dilution factor, expressed in units of 1 / s; The value represents the boron dilution rate, expressed in ppm / s. This represents the boron concentration at the beginning of the current cycle, in ppm.

[0078] (Equation 10); in, The value represents the boron dilution rate, expressed in ppm / s. The boron concentration at the beginning of the cycle is expressed in ppm. The boron concentration at the end of the cycle is expressed in ppm. The period is measured in seconds (s).

[0079] The boron concentration in the primary coolant is: .

[0080] It should be noted that in actual operation, when the boron concentration... When the boron concentration drops to a certain level, it reaches the limit for wastewater purification. After that, the boron concentration was no longer diluted by water drainage. This means that the boron dilution rate is zero, and the actual boron concentration at this point is not higher than the boron concentration limit for wastewater purification. .

[0081] Understandably, theoretical calculations of boron dilution rates require reducing boron concentration through drainage. However, in the later stages of the cycle when boron concentration is low, a large amount of coolant needs to be added to further reduce it, leading to a significant increase in the total mass of the primary coolant and a sharp decrease in the nuclide concentrations of various fission products. This does not align with actual operating conditions. Therefore, the above embodiments use boron concentration drainage purification limits considered during actual operation. The formula for calculating the boron dilution rate has been adjusted to avoid the aforementioned problems.

[0082] In one embodiment of this application, the first prediction model includes the release rate of each fission product into the primary coolant within the current operating range through broken cladding, fission of contaminated uranium, and release of corroded uranium.

[0083] During the operation of pressurized water reactor nuclear power plants, fission products are released not only into the primary coolant through cladding failure, but also through the fission of contaminated uranium and the release of eroded uranium. Therefore, when constructing the first prediction model, the relationship between the release rate and time under different release methods can be established separately.

[0084] Based on the above calculation formula, the formula for calculating the release rate of fission products into the primary coolant through broken shells and released actinide nuclides is as follows: (Equation 11); in, The rate at which fission products are released into the primary coolant through broken shells and released actinide nuclides is expressed in atoms / s. The rate at which fission products are released into the primary coolant through the broken shell, expressed in atoms / s; The rate at which fission products are released into the primary coolant via the fission of contaminated uranium, expressed in atoms / s; The rate at which fission products are released into the primary coolant through the erosion of uranium is expressed in atoms / s.

[0085] The above The calculation formula is as follows: (Equation 12); in, N represents the rate at which fission products are released into the primary coolant via the fission of contaminated uranium at time t, expressed in atoms / s. k,ac The number of nucleons of the fissile isotope k contaminated on the damaged shell, expressed in atoms; The average neutron flux density in the irradiated area is expressed in units of 1000 ppm. ;σ f,k The microscopic fission cross section of fissile nuclide k is shown in cm. 2 ;ε i,k The fission yield of fissionable nuclide k to produce nuclide i is dimensionless.

[0086] The above The calculation formula is as follows: (Equation 13); in, Q represents the rate at which fission products are released into the primary coolant through uranium erosion at time t, expressed in atoms / s. r The mass flow rate of the fissile material inside the damaged cladding entering the primary coolant is expressed in g / s; C zi The concentration of nuclide i in the fissile material inside the shell is expressed in atoms / g.

[0087] (Equation 14); Where Vd is the total deposition and disappearance coefficient of suspended particulate nuclides, in units of Vdg is the nuclide deposition coefficient in the steam generator region, in units of... Vdc is the nuclide deposition coefficient in the core region, in units of... Vec is the nuclide release coefficient deposited in the core region, in units of... Veg is the nuclide release coefficient deposited in the steam generator region, in units of... .

[0088] (Equation 15); in, Vrcp represents the mass of the primary coolant in g; Vrcp represents the volume of the primary coolant in cm³. 3 , This refers to the density of the coolant, expressed in g / cm³. 3 .

[0089] The density of the coolant is calculated as follows: (Equation 16); in, This refers to the density of the coolant, expressed in g / cm³. 3Tin is the primary coolant temperature at the core inlet, in degrees Celsius; Tout is the primary coolant temperature at the core outlet, in degrees Celsius.

[0090] The release rate of each fission product into the primary coolant can be obtained through the above implementation method. Based on the release rate and the remaining time within the cycle interval, a first correspondence between the predicted nuclide concentration and time can be constructed. The first prediction model includes the first correspondence for each fission product.

[0091] In one embodiment of this application, determining the predicted peak value of the third nuclide concentration of each fission product in the primary coolant during the shutdown interval based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters includes: The operating parameters and the fuel damage parameters are input into the second prediction model to obtain the second correspondence between each fission product within the shutdown interval; wherein, the second correspondence is the correspondence between the release rate of each fission product and time. Based on the second nuclide concentration prediction value and the second correspondence of each fission product in the shutdown interval, the third nuclide concentration prediction peak value of each fission product in the primary coolant in the shutdown interval is determined.

[0092] In this embodiment, after inputting the operating parameters of the current cycle process and the fuel damage parameters obtained in the above implementation method into the preset second prediction model, the second correspondence of each fission product in the shutdown interval can be obtained. The second correspondence is the correspondence between the release rate of each fission product and time from the shutdown transient state.

[0093] Understandably, assuming that the release rate of fission products from the fuel cladding through the broken cladding into the primary coolant is directly proportional to the amount of nuclides accumulated in the fuel assembly and the proportion of fuel cladding damage, a formula for calculating the release rate of each fission product through the broken cladding into the primary coolant can be constructed based on this. After building a second prediction model based on the constructed release rate formula, a second correspondence between each fission product can be generated using the second prediction model.

[0094] After obtaining the second correspondence of each fission product, the predicted peak value of the third nuclide concentration of each fission product in the primary coolant during the shutdown interval can be determined by combining the predicted value of the second nuclide concentration of each fission product at the end of the current operating interval.

[0095] As an example, based on the second correspondence of each fission product and the second nuclide concentration prediction value of each fission product at the end of the current operating interval, the nuclide concentration prediction value of each fission product at any time within the shutdown interval can be determined. Within the shutdown interval, the nuclide concentration prediction values ​​of each fission product typically increase first and then decrease. Therefore, after determining the third nuclide concentration prediction peak value of each fission product, starting from the time corresponding to this third nuclide concentration prediction peak value, based on the aforementioned correspondence between the release rate and time of each fission product, a nuclide concentration prediction value versus time correspondence can be generated and displayed to relevant personnel in the form of a curve. This curve represents the concentration decrease curve after the nuclide concentration reaches its peak.

[0096] In one embodiment of this application, the second prediction model includes the release rate of each fission product into the primary coolant through the broken cladding during a reactor shutdown transient.

[0097] When a pressurized water reactor nuclear power plant is shut down, the reaction process stops, and the fission products are released into the primary circuit only through the broken cladding. The release rate can be constructed by the corresponding relationship between the release kinetic coefficient and time.

[0098] As an example, it is assumed that the release rate of fission products from the fuel cladding into the primary coolant through a damaged cladding is proportional to the amount of nuclides accumulated in the fuel and the proportion of fuel cladding damage. Based on this, a formula can be constructed to calculate the release rate of fission products into the primary coolant through a damaged cladding, as follows: (Equation 17); in, The rate at which fission products are released into the primary coolant through the broken shell, expressed in atoms / s; The amount of fission product nuclide i accumulated in the fuel cladding interstitial space at time t, in atoms; The release rate coefficient of fission product nuclides into the coolant during reactor shutdown transients, expressed in seconds. -1 ; The percentage of damaged fuel rod casings in the IC zone is the number of damaged fuel rods divided by the total number of fuel rods in the zone; it is dimensionless.

[0099] (Equation 18); in, The percentage of fuel rod cladding damage in IC zone is dimensionless. This represents the number of damaged fuel rods within the IC partition. This represents the total number of fuel rods within the IC partition.

[0100] Based on the above implementation method, by calculating and summing the values ​​for each core section, the release rate of coolant from the cladding gaps to the primary coolant in the entire core can be obtained. The corresponding calculation formula is as follows: (Equation 19); in, The rate at which coolant is released from the cladding gaps into the primary coolant circuit throughout the entire reactor core, expressed in atoms / s; The rate at which fission products are released into the primary coolant through the broken cladding is expressed in atoms / s.

[0101] Release rate coefficient of fission product nuclides into coolant during reactor shutdown transients The calculation formula is as follows: , ; , ; , ; Among them, v i,II (t') is the release kinetic coefficient of nuclide i at time t', with units of 1 / s; The exponential growth factor of the dynamic coefficient for the release of the second type of transient (i.e., reactor shutdown transient) conditions, in units of 1 / s; The initial release dynamics coefficient during reactor shutdown transients is expressed in units of 1 / s. The nuclide release kinetic coefficient for achieving a stable release state during reactor shutdown, expressed in units of 1 / s; The time for the release kinetic coefficient to reach its peak, expressed in seconds; The unit is seconds (s) and is used to characterize the time it takes for the release kinetic coefficient to reach the final stability coefficient during the reactor shutdown transient.

[0102] Understandably, during a reactor shutdown transient, the aforementioned release kinetic coefficient exhibits a pattern of rapid increase to a peak value during the transient period, followed by a gradual decay to a stable value.

[0103] In one embodiment of this application, two hours after the reactor is shut down by inserting a control rod, a certain fission product in the primary coolant can reach the peak concentration during the shutdown transient.

[0104] In one embodiment of this application, the correction of the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the updated first nuclide concentration includes: The first correspondence is corrected based on the updated first nuclide concentrations of each fission product; The predicted values ​​of the second nuclide concentration and the predicted peak value of the third nuclide concentration are corrected based on the corrected first correspondence.

[0105] In this embodiment, the device can pre-set a corresponding time interval as a time step. At each time step, after updating the first nuclide concentration of each fission product, the first correspondence obtained in the previous time step can be corrected based on the updated first nuclide concentration of each fission product.

[0106] As an example, there is a certain difference between the first nuclide concentration of each fission product obtained at the current time step and the predicted nuclide concentration of each fission product at the current time step obtained in the previous time step based on the first correspondence. In this case, the first correspondence can be corrected based on the first nuclide concentration of each fission product obtained at the current time step.

[0107] Understandably, at the current time step, the device has already obtained the first nuclide concentrations of each fission product at the current time step and at multiple previous time steps. For each fission product, after smoothing the first nuclide concentrations at multiple time steps, the functional relationship of the first correspondence can be corrected using the least squares method or other optimization algorithms.

[0108] In one embodiment of this application, the step of correcting the first correspondence based on the updated first nuclide concentrations of each fission product includes: Based on the first nuclide concentrations of each fission product at previous measurement time points and the updated first nuclide concentrations of each fission product, the first correspondences of each fission product are fitted and corrected to obtain the corrected first correspondences.

[0109] In this embodiment, taking a single fission product as an example, after updating the first nuclide concentration of each fission product at the current time step, multiple previous measurement time points can be obtained, that is, the first nuclide concentration of each fission product measured at each of the previous multiple time steps. The first nuclide concentrations of each fission product mentioned above are measured values, not predicted values. Based on the first nuclide concentrations at each of the above time points, the first correspondence of the fission product can be fitted and corrected to obtain the corrected first correspondence. It is understood that the above fitting and correction algorithm can be the least squares method.

[0110] The above implementation methods can be performed separately for each fission product, thereby correcting the first correspondence between each fission product.

[0111] In one embodiment of this application, after determining the predicted concentration values ​​of the second nuclides of each fission product in the primary coolant at the end of the current operating interval based on the first correspondence, the method further includes: Obtain the preset concentration limits for each fission product; Based on the predicted concentration values ​​of the second nuclide of each fission product and the corresponding concentration limits, it is determined whether each fission product exceeds the limit within the current operating range.

[0112] In this embodiment, after obtaining the predicted concentration values ​​of the second nuclide in the primary coolant at the end of the current operating range for each fission product, preset concentration limits for each fission product can be obtained. For each fission product, the concentration limit can be compared with the predicted concentration value of the second nuclide, and the comparison result can be used to determine whether the fission product exceeds the limit within the current operating range.

[0113] Understandably, the predicted value of the second nuclide concentration is the nuclide concentration at the end of the current operating interval. If the predicted value exceeds the concentration limit, it means that the nuclide concentration of the fission product will exceed the limit in the remaining time of the current operating interval, and relevant personnel need to be warned in time to formulate relevant protective measures.

[0114] In one embodiment of this application, after determining whether each fission product exceeds the limit within the current operating range based on the predicted concentration value of the second nuclide of each fission product and the corresponding concentration limit, the method further includes: If at least one fission product exceeds the limit in the current operating range, the time node corresponding to the predicted nuclide concentration reaching the concentration limit corresponding to the target fission product is determined according to the first correspondence relationship corresponding to the target fission product; wherein, the target fission product is the fission product that exceeds the limit in the current operating range among multiple fission products.

[0115] In this embodiment, after determining whether each fission product will exceed the limit within the current operating range as described above, if at least one fission product exceeds the limit within the current operating range, then that fission product can be identified as the target fission product.

[0116] Based on the first correspondence with the target fission products, the correspondence between the predicted nuclide concentration and time within the remaining time of the current operating interval can be determined. By combining the first correspondence with the concentration limit corresponding to the target fission product, the time point at which the predicted nuclide concentration reaches the concentration limit can be obtained. In other words, based on the first correspondence and the concentration limit, it is possible to predict when the nuclide concentration of the target fission product will reach the concentration limit.

[0117] In one embodiment of this application, after correcting the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the updated first nuclide concentration, the method further includes: After a preset prediction period, the concentration of the first nuclide of each fission product in the primary coolant and the operating parameters are reacquired, and the process returns to the step: based on a preset fuel cladding damage diagnosis algorithm, the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters are determined until the pressurized water reactor nuclear power plant is shut down.

[0118] In this embodiment, after each preset prediction cycle, the first nuclide concentration and operating parameters of each fission product in the primary coolant can be reacquired, and the process returns to step 102 above. Based on the reacquired first nuclide concentration and operating parameters, the predicted value of the second nuclide concentration of each fission product at the end of the current operating interval and the predicted peak value of the third nuclide concentration in the shutdown interval are determined until the pressurized water reactor nuclear power plant is shut down.

[0119] It is understood that the time step in the above embodiments is different from the prediction period in this embodiment. The time step in the above embodiments refers to a smaller time interval, such as one minute; while the prediction period in this embodiment refers to a larger time interval, such as sixty minutes.

[0120] As an example, within the same prediction period, at each time step, only the concentration of the first nuclide of each fission product is updated, and the first correspondence already generated within that prediction period is corrected based on the updated first nuclide concentration. That is, within the same prediction period, only the already generated first correspondence is corrected.

[0121] In the next prediction cycle, not only will the concentrations of the first nuclides of each fission product be reacquired, but the fuel damage parameters, the predicted values ​​of the second nuclide concentrations of each fission product, and the predicted peak values ​​of the third nuclide concentrations will also be regenerated based on the fuel cladding damage diagnosis algorithm, the first prediction model, and the second prediction model. In other words, a new first correspondence will be generated in the next prediction cycle, rather than a correction of the first correspondence in the previous prediction cycle.

[0122] In one embodiment of this application, after predicting the trend of nuclide concentration changes of the primary coolant fission products during the remaining time of the current cycle operation, and the peak nuclide concentration of the primary coolant fission products under shutdown conditions, based on the above-described implementation methods, these can be displayed to relevant personnel in the form of graphs and text. If the trend of nuclide concentration changes of the primary coolant fission products during the remaining time will exceed the concentration limit in the operating technical specifications, the time point at which the nuclide concentration reaches the concentration limit during the remaining time can be further calculated. The conclusion that the nuclide concentration of a certain fission product in the current operating interval will exceed the concentration limit, and the time point at which the concentration limit is reached, can also be displayed. Relevant personnel can take early intervention actions based on the displayed content, such as increasing the purification flow rate, shutting down the reactor earlier, and putting the degassing tower into operation to reduce the concentration of fission gas in the primary coolant.

[0123] As an example, the aforementioned fuel cladding damage diagnosis algorithm and first prediction model can be integrated into the fission product source term calculation software in the primary coolant. After the equipment is installed with this software, the changes in the nuclide concentration of fission products in the subsequent operating range can be calculated by inputting the fuel cladding damage status, current operating history, and future operating conditions.

[0124] Figure 3 A schematic diagram of the structure of a peak fission product prediction device for a pressurized water reactor nuclear power plant provided in an embodiment of this application is shown. Figure 3 As shown, the fission product peak prediction device 300 for a pressurized water reactor nuclear power plant includes: The acquisition module 301 is used to acquire the concentration of the first nuclide of each fission product and the operating parameters of the primary coolant in the primary loop at the current moment within the operating range of the pressurized water reactor nuclear power plant. The damage determination module 302 is used to determine the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters based on a preset fuel cladding damage diagnosis algorithm. The first concentration prediction module 303 is used to determine the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval based on the first prediction model, the operating parameters and the fuel damage parameters. The second concentration prediction module 304 is used to determine the predicted peak value of the third nuclide concentration of each fission product in the primary coolant within the shutdown interval based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters.

[0125] In one embodiment of this application, the device further includes an update module and a correction module; The update module is used to update the concentration of the first nuclide of each fission product in the primary coolant within the operating range of the pressurized water reactor nuclear power plant, based on a preset measurement interval. The correction module is used to correct the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the updated first nuclide concentration.

[0126] In one embodiment of this application, the acquisition module is further configured to sample the primary coolant at the current moment to obtain a sample; perform radioactivity analysis on the sample to obtain the first nuclide concentration of each fission product; or, perform online spectrum measurement on the primary coolant at the current moment based on a preset online spectrum measurement module to obtain the first nuclide concentration of each fission product.

[0127] In one embodiment of this application, the fuel damage parameters include the number of damaged components, the size of the rupture, and the fuel consumption range of the damaged components; The damage determination module is further configured to: determine fuel damage characteristic parameters based on the first nuclide concentration of the first characteristic fission product; determine whether fuel cladding damage exists based on the fuel damage characteristic parameters; if fuel cladding damage exists, determine the number of damaged components in the fuel cladding based on the first nuclide concentration of some fission products; determine the equivalent escape rate coefficient ratio of some nuclide combinations based on the first nuclide concentration of each fission product; determine the tear size of the fuel cladding based on the equivalent escape rate coefficient ratio and the number of damaged components; and determine the burnup range of the damaged components in the fuel cladding based on the first nuclide concentration of some fission products and the number of damaged components.

[0128] In one embodiment of this application, the first concentration prediction module is further configured to input the operating parameters, the number of damaged components, the size of the breach, and the burnup range of the damaged components into the first prediction model to obtain a first correspondence between each fission product in the primary coolant within the current operating interval; wherein, the first correspondence is a correspondence between the predicted nuclide concentration value and time; based on the first correspondence, a second predicted nuclide concentration value of each fission product in the primary coolant at the end of the current operating interval is determined.

[0129] In one embodiment of this application, the second concentration prediction module is further configured to input the operating parameters and the fuel damage parameters into the second prediction model to obtain a second correspondence between each fission product within the shutdown interval; wherein, the second correspondence is the correspondence between the release rate and time of each fission product; based on the second nuclide concentration prediction value and the second correspondence between each fission product within the shutdown interval, the third nuclide concentration prediction peak value of each fission product in the primary coolant within the shutdown interval is determined.

[0130] In one embodiment of this application, the correction module is further configured to correct the first correspondence based on the updated first nuclide concentration of each fission product; and to correct the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the corrected first correspondence.

[0131] In one embodiment of this application, the correction module is specifically used to fit and correct the first correspondence relationship corresponding to each fission product based on the first nuclide concentration of each fission product corresponding to the prior multiple measurement time points and the updated first nuclide concentration of each fission product, so as to obtain the corrected first correspondence relationship.

[0132] In one embodiment of this application, the acquisition module is further configured to acquire preset concentration limits for each fission product; and based on the predicted concentration value of the second nuclide of each fission product and the corresponding concentration limit, determine whether each fission product exceeds the limit in the current operating range.

[0133] In one embodiment of this application, the device further includes a processing module; The processing module is used to determine the time node corresponding to the predicted nuclide concentration reaching the concentration limit of the target fission product when at least one fission product exceeds the limit in the current operating range, based on the first correspondence relationship corresponding to the target fission product; wherein, the target fission product is the fission product that exceeds the limit in the current operating range among multiple fission products.

[0134] In one embodiment of this application, the damage determination module is further configured to, after a preset prediction period, reacquire the first nuclide concentration and operating parameters of each fission product in the primary coolant, and determine the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters based on a preset fuel cladding damage diagnosis algorithm, until the pressurized water reactor nuclear power plant is shut down.

[0135] The fission product peak prediction device for pressurized water reactor nuclear power plants provided in this application embodiment can realize all the processes implemented in the aforementioned pressurized water reactor nuclear power plant fission product peak prediction method embodiment and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0136] Figure 4 A schematic diagram of the hardware structure of the electronic device provided in an embodiment of this application is shown.

[0137] The electronic device may include a processor 401 and a memory 402 storing computer program instructions.

[0138] Specifically, the processor 401 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0139] Memory 402 may include mass storage for data or instructions. For example, and not limitingly, memory 402 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 402 may include removable or non-removable (or fixed) media. Where appropriate, memory 402 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 402 is non-volatile solid-state memory.

[0140] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to the first aspect of this disclosure.

[0141] The processor 401 implements any of the methods described above in the above embodiments by reading and executing computer program instructions stored in the memory 402.

[0142] In one example, the electronic device may also include a communication interface 403 and a bus 410. For example, Figure 4 As shown, the processor 401, memory 402, and communication interface 403 are connected through bus 410 and complete communication with each other.

[0143] The communication interface 403 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0144] Bus 410 includes hardware, software, or both, that couples components of a method or electronic device as described above together. For example, and not as a limitation, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 410 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0145] Alternatively, embodiments of this application can be implemented using a computer storage medium. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the fission product peak prediction methods for pressurized water reactor nuclear power plants described in the above embodiments.

[0146] In addition, this application embodiment can provide a computer program product for implementation, wherein when the instructions in the computer program product are executed by the processor of an electronic device, the electronic device implements any of the fission product peak prediction methods for pressurized water reactor nuclear power plants in the above embodiments.

[0147] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described as examples. However, the method process of this application is not limited to the specific steps described. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0148] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0149] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0150] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0151] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for predicting the peak fission products of a pressurized water reactor nuclear power plant, characterized in that, The method includes: Within the operating range of a pressurized water reactor nuclear power plant, obtain the concentration of the first nuclide of each fission product and the operating parameters in the primary coolant at the current moment; Based on a preset fuel cladding damage diagnosis algorithm, the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters are determined; Based on the first prediction model, the operating parameters, and the fuel damage parameters, the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval are determined. Based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters, the predicted peak values ​​of the third nuclide concentrations of each fission product in the primary coolant within the shutdown interval are determined.

2. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 1, characterized in that, After determining the predicted peak values ​​of the third nuclide concentrations of each fission product in the primary coolant within the shutdown interval based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters, the method further includes: Within the operating range of a pressurized water reactor nuclear power plant, the concentration of the first nuclide of each fission product in the primary coolant is updated based on a preset measurement interval. The predicted values ​​of the second nuclide concentration and the predicted peak value of the third nuclide concentration are corrected based on the updated first nuclide concentration.

3. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 2, characterized in that, The process of obtaining the first nuclide concentration of each fission product in the primary coolant at the current moment includes: A sample of the primary coolant at the current moment is obtained; Radioactive analysis was performed on the sampled material to obtain the concentration of the first nuclide in each fission product. Alternatively, the primary coolant at the current moment can be measured online using a preset online spectrum measurement module to obtain the first nuclide concentration of each fission product.

4. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 2, characterized in that, The operating parameters include: fuel loading parameters, power variation parameters, primary loop purification flow rate, primary loop purification and decontamination efficiency, and primary loop water loading volume for the current cycle process of the pressurized water reactor nuclear power plant.

5. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 2, characterized in that, The fuel damage parameters include the number of damaged components, the size of the puncture, and the fuel consumption range of the damaged components; The fuel cladding damage diagnosis algorithm, based on a preset algorithm, determines the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters, including: Based on the concentration of the first nuclide in the first characteristic fission product, fuel damage characteristic parameters are determined. Determine whether fuel coating damage exists based on the aforementioned fuel damage characteristic parameters; In the presence of fuel cladding defects, the number of defective components in the fuel cladding is determined based on the concentration of the first nuclide in some fission products. Based on the first nuclide concentration of each fission product, the equivalent escape rate coefficient ratio of some nuclide combinations is determined; The size of the puncture in the fuel cladding is determined based on the equivalent escape rate coefficient ratio and the number of damaged components. The burnup range of the damaged components in the fuel cladding is determined based on the concentration of the first nuclide in some fission products and the number of damaged components.

6. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 5, characterized in that, The determination of the predicted concentrations of the second nuclides of each fission product in the primary coolant at the end of the current operating interval, based on the first prediction model, the operating parameters, and the fuel damage parameters, includes: The operating parameters, the number of damaged components, the size of the breach, and the burnup range of the damaged components are input into the first prediction model to obtain the first correspondence between each fission product in the primary coolant within the current operating range; wherein, the first correspondence is the correspondence between the predicted nuclide concentration and time. Based on the first correspondence, the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval are determined.

7. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 6, characterized in that, The first prediction model includes the release rate of each fission product into the primary coolant within the current operating range through broken cladding, fission of contaminated uranium, and release of corroded uranium.

8. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 2, characterized in that, The determination of the predicted peak values ​​of the third nuclide concentrations of each fission product in the primary coolant during the shutdown period, based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters, includes: The operating parameters and the fuel damage parameters are input into the second prediction model to obtain the second correspondence between each fission product within the shutdown interval; wherein, the second correspondence is the correspondence between the release rate of each fission product and time. Based on the second nuclide concentration prediction value and the second correspondence of each fission product in the shutdown interval, the third nuclide concentration prediction peak value of each fission product in the primary coolant in the shutdown interval is determined.

9. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 8, characterized in that, The second prediction model includes the release rate of each fission product into the primary coolant through the broken cladding during a reactor shutdown transient.

10. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 6, characterized in that, The correction of the predicted values ​​of the second nuclide concentration and the predicted peak values ​​of the third nuclide concentration based on the updated first nuclide concentration includes: The first correspondence is corrected based on the updated first nuclide concentrations of each fission product; The predicted values ​​of the second nuclide concentration and the predicted peak value of the third nuclide concentration are corrected based on the corrected first correspondence.

11. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 10, characterized in that, The correction of the first correspondence based on the updated first nuclide concentrations of each fission product includes: Based on the first nuclide concentrations of each fission product at previous measurement time points and the updated first nuclide concentrations of each fission product, the first correspondences of each fission product are fitted and corrected to obtain the corrected first correspondences.

12. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 6, characterized in that, After determining the predicted concentration values ​​of the second nuclides of each fission product in the primary coolant at the end of the current operating interval based on the first correspondence, the method further includes: Obtain the preset concentration limits for each fission product; Based on the predicted concentration values ​​of the second nuclide of each fission product and the corresponding concentration limits, it is determined whether each fission product exceeds the limit within the current operating range.

13. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 12, characterized in that, After determining whether each fission product exceeds the limit within the current operating range based on the predicted concentration values ​​of the second nuclides of each fission product and the corresponding concentration limits, the method further includes: If at least one fission product exceeds the limit in the current operating range, the time node corresponding to the predicted nuclide concentration reaching the concentration limit corresponding to the target fission product is determined according to the first correspondence relationship corresponding to the target fission product; wherein, the target fission product is the fission product that exceeds the limit in the current operating range among multiple fission products.

14. The method for predicting the peak fission products of a pressurized water reactor nuclear power plant according to claim 10, characterized in that, After correcting the predicted value of the second nuclide concentration and the predicted peak value of the third nuclide concentration based on the updated first nuclide concentration, the method further includes: After a preset prediction period, the concentration of the first nuclide of each fission product in the primary coolant and the operating parameters are reacquired, and the process returns to the step: based on a preset fuel cladding damage diagnosis algorithm, the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters are determined until the pressurized water reactor nuclear power plant is shut down.

15. A device for predicting peak fission products in a pressurized water reactor nuclear power plant, characterized in that, The device includes: The acquisition module is used to acquire the concentration of the first nuclide of each fission product and the operating parameters of the primary coolant in the primary loop at the current moment within the operating range of the pressurized water reactor nuclear power plant. The damage determination module is used to determine the fuel damage parameters corresponding to the first nuclide concentration and the operating parameters based on a preset fuel cladding damage diagnosis algorithm. The first concentration prediction module is used to determine the predicted values ​​of the second nuclide concentrations of each fission product in the primary coolant at the end of the current operating interval based on the first prediction model, the operating parameters and the fuel damage parameters. The second concentration prediction module is used to determine the predicted peak value of the third nuclide concentration of each fission product in the primary coolant within the shutdown interval based on the second prediction model, the second nuclide concentration prediction value, the operating parameters, and the fuel damage parameters.

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