Reactor power distribution test method and system based on in-core self-powered detector

Abstract

The present invention discloses a reactor power distribution test method and system based on an in-core self-powered detector, which relates to the field of nuclear reactor physical tests. The key points of the technical solution are: after simulating the fine power distribution of the core under each transient state, a core theoretical database is established, and the coupling coefficient of each node in each fuel assembly is established by a coupling coefficient method; fixed and discrete measured current data collected by the in-core self-powered detector are obtained, and continuous power distribution information is obtained by a high-order fitting method; based on the coupling coefficient and the continuous power distribution information, the measured power distribution of the whole stack is obtained by using online power distribution expansion software; the fine power distribution of the core under transient state is compared with the measured power distribution of the whole stack to obtain the power distribution deviation test result. Based on the calculation of the transient core power distribution, the present invention is combined with the real-time in-core self-powered detector current to give the measured power distribution of the current core state.

Description

Technical Field

[0001] The present invention relates to the field of nuclear reactor physical tests, and more specifically, to a reactor power distribution test method and system based on an in-core self-powered detector. Background Art

[0002] Since the economic benefits of nuclear power plants are closely related to the full-power operation time, the stabilization time of the power distribution test directly affects the load factor of the nuclear power plant. Excessive stabilization time directly reduces the economic benefits of the power plant. Therefore, many nuclear power plants have carried out power increase test optimization research in actual operation. The current main idea is to use simulation calculations to wait for different time intervals after the power increase is completed, and find the waiting time interval with a smaller deviation from the key parameters of the core in the theoretical xenon equilibrium state. This interval is used as the power increase waiting time. After completing the comparative analysis of the theoretical calculated values, the waiting time interval at each power increase platform is determined, and the theoretical value is compared with the measured value at this interval to verify whether the relevant acceptance criteria are met. The above method can be used in the physical test of the startup of some nuclear power plants, mainly because after waiting for the time interval that makes the parameter deviation smaller, the core data measurement takes about 2 hours to complete, and after the waiting time interval is completed, the measurement starts, and the core parameters change less. The data in the entire measurement process can be regarded as the data obtained by measuring immediately after the waiting time is completed. However, the main problem with this method is that it depends on the specific results of the test data to determine whether it is possible to shorten the waiting time. Generally speaking, the xenon poison concentration in the core does not reach the equilibrium state when the waiting time is shortened, and the calculation result is conservative relative to the xenon equilibrium state. Therefore, it is easy to encounter the situation that the relevant acceptance criteria cannot be met after shortening the waiting time, resulting in an over-limit situation. It is still necessary to wait for 24 hours before conducting a supplementary test, resulting in an additional increase in test operations. At the same time, the main theoretical basis of this method is that the deviation between the measured data and the theoretical design value after the shortened time is greater than the deviation between the measured value and the theoretical design value under the equilibrium xenon state, but the disturbance of the non-equilibrium xenon distribution to the power distribution does not necessarily increase the deviation, so that the safety of the reactor cannot be verified.

[0003] To this end, the prior art records a Chinese patent application with publication number CN114266157A and the name of the method, device and equipment for realizing reactor power distribution test at any time. It uses a high-precision core calculation program to model the core, accurately calculates the theoretical database of the reactor core at any time, and obtains the measured core power distribution in combination with the current data of the detector at the current moment, and compares it with the theoretical design value of the core obtained by the high-precision core calculation program to achieve the purpose of verifying the core power distribution, and solves the problem that the power increase test needs to wait for the core to reach the xenon equilibrium state. However, the above document is aimed at the second-generation nuclear power plant, and the in-core current uses a movable detector to obtain the in-core current, and the in-core current can only be measured under fixed cycles (generally 30 equivalent full-power days). Specifically, a mobile cart is used to gradually insert and remove the detector to obtain the measured current information of each detector component, which is characterized by non-real-time and multi-point continuous measurement.

[0004] With the continuous development of the third-generation nuclear power plants, fixed self-powered detectors are installed in the reactor, and the traditional non-real-time, continuous measurement power distribution expansion method is no longer applicable. Therefore, how to study and design a reactor power distribution test method and system based on in-pile self-powered detectors that can overcome the above defects is an urgent problem to be solved. Summary of the invention

[0005] In order to address the deficiencies in the prior art, the purpose of the present invention is to provide a reactor power distribution test method and system based on an in-core self-powered detector, a power distribution reconstruction method based on a coupling coefficient method, a high-order fitting method and in-core fine power distribution calculation, which effectively solves the problem of expanding the three-dimensional power distribution of the whole reactor under fixed and discrete current data; based on the calculation of transient core power distribution, combined with the real-time in-core self-powered detector current, the measured power distribution of the current core state can be given.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] In a first aspect, a reactor power distribution test method based on an in-core self-powered detector is provided, comprising the following steps:

[0008] The core theoretical database is established by simulating the core fine power distribution under various transient conditions using the three-dimensional core fine power distribution calculation software, and the coupling coefficient of each node in each fuel assembly is established using the coupling coefficient method;

[0009] Obtain fixed and discrete measured current data collected by the in-pile self-powered detector, and use high-order fitting methods to expand it to obtain continuous power distribution information;

[0010] Based on the coupling coefficient and continuous power distribution information, the online power distribution expansion software is used to expand the measured power distribution of the whole reactor;

[0011] The fine power distribution of the core under transient state is compared with the measured power distribution of the whole reactor to obtain the power distribution deviation test results.

[0012] Furthermore, the simulation process of the core fine power distribution is specifically as follows:

[0013] During the simulation of the reactor power distribution test process, after the simulated core power rise reaches the target power platform, the core power distribution is calculated after the preset waiting time X, and the theoretical values ​​of the core key parameters are obtained based on the core power distribution calculation;

[0014] The core power increase process is simulated, and the next power platform test simulation is entered. The theoretical calculation of the key parameters of the core under all power platforms is completed to obtain the core theoretical database of the test process.

[0015] Furthermore, the core fine power distribution simulation calculates the flux distribution and power distribution of each core segment in the three-dimensional core by considering the fuel burnup and the short half-life high absorption cross-section nuclide burnup.

[0016] Furthermore, the simulation calculation formula of the fuel consumption is specifically as follows:

[0017]

[0018] Among them, N i represents the nucleon density of the ith nuclide; n represents the total number of nuclides in the system; β represents the reaction coefficient between nuclides, including decay, fission and capture reaction processes; β j→i represents the reaction rate of the jth nuclide to generate the i-th nuclide, β i represents the disappearance rate of the ith nuclide; N j (0) represents the nucleon density of the jth nuclide at time 0; N 0,j represents the nucleon density of the jth nuclide at the initial moment.

[0019] Furthermore, the short half-life high absorption cross-section nuclide burnup includes iodine nuclide burnup and xenon nuclide burnup.

[0020] Furthermore, the simulation calculation formula of the iodine nuclide burnup is specifically as follows:

[0021]

[0022] Among them, N I (t) represents the nuclear density of iodine at time t; γ I represents the fission share of iodine; Σ frepresents the fission cross section; φ(t) represents the neutron flux at time t; λ I represents the decay constant of iodine.

[0023] Furthermore, the simulation calculation formula of the xenon nuclide burnup is specifically as follows:

[0024]

[0025] Among them, N Xe (t) represents the nucleon density at xenon t; γ Xe represents the fission fraction of xenon; Σ f represents the fission cross section; φ(t) represents the neutron flux at time t; λ I represents the decay constant of iodine; N I (t) represents the nuclear density of iodine at time t; λ Xe represents the decay constant of xenon; σ a,Xe represents the microscopic absorption cross section of xenon.

[0026] Secondly, a reactor power distribution test system based on an in-core self-powered detector is provided, including:

[0027] The simulation module is used to establish a core theoretical database after simulating the core fine power distribution under various transient states using a three-dimensional core fine power distribution calculation software, and to establish the coupling coefficient of each node in each fuel assembly using a coupling coefficient method;

[0028] The measurement module is used to obtain fixed and discrete measured current data collected by the in-pile self-powered detector, and expand it to obtain continuous power distribution information using a high-order fitting method;

[0029] The reconstruction module is used to obtain the measured power distribution of the whole reactor based on the coupling coefficient and continuous power distribution information by using the online power distribution expansion software;

[0030] The verification module is used to compare the core fine power distribution under transient conditions with the measured power distribution of the entire reactor to obtain the power distribution deviation test results.

[0031] In a third aspect, a computer terminal is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a reactor power distribution test method based on an in-core self-powered detector as described in any one of the first aspects is implemented.

[0032] In a fourth aspect, a computer-readable medium is provided, on which a computer program is stored, and the computer program is executed by a processor to implement a reactor power distribution test method based on an in-core self-powered detector as described in any one of the first aspects.

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

[0034] 1. The reactor power distribution test method based on the in-core self-powered detector proposed in the present invention, and the power distribution reconstruction method based on the coupling coefficient method, the high-order fitting method and the in-core fine power distribution calculation, effectively solve the problem of the three-dimensional power distribution expansion of the whole reactor under fixed and discrete current data; based on the transient core power distribution calculation, combined with the real-time in-core self-powered detector current, the measured power distribution of the current core state can be given.

[0035] 2. The present invention can complete the power distribution test without any hardware modification, and the reduction of the waiting time for the power platform will not affect other tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0037] Figure 1 is a flow chart in an embodiment of the present invention;

[0038] Figure 2 is a system block diagram in an embodiment of the present invention;

[0039] Figure 3 This is a typical core loading diagram of Hualong One in an embodiment of the present invention;

[0040] Figure 4 is the power distribution of 50% power platform components in the embodiment of the present invention;

[0041] Figure 5 It is the power deviation of the 50% power platform component of the stable 24h result of the existing technology;

[0042] Figure 6 It is the 50% power platform component power deviation of the stable 0 result in the embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0044] Embodiment 1: A reactor power distribution test method based on an in-core self-powered detector comprises the following steps:

[0045] S1: Use three-dimensional core fine power distribution calculation software to simulate the core fine power distribution under various transient conditions to establish a core theoretical database, and use the coupling coefficient method to establish the coupling coefficient of each node in each fuel assembly; the three-dimensional core fine power distribution calculation software can use CORCA-3D;

[0046] S2: Obtain fixed and discrete measured current data collected by the in-pile self-powered detector, and use high-order fitting methods to expand it to obtain continuous power distribution information;

[0047] S3: Based on the coupling coefficient and continuous power distribution information, the online power distribution expansion software is used to expand the measured power distribution of the whole reactor; the online power distribution expansion software can use RAINBOW;

[0048] S4: Compare the transient core fine power distribution with the measured power distribution of the whole reactor to obtain the power distribution deviation test result.

[0049] The present invention uses a high-precision core calculation program to achieve accurate calculation of core parameters under non-xenon equilibrium conditions in the reactor. At the same time, the core theoretical database after the set stabilization time is obtained according to the set reactor operating condition change level. Combined with the core self-powered detector signal, the full-heap measured current data after the set stabilization time is obtained, thereby obtaining the core measured parameters at any time, and comparing them with the theoretical design values ​​to complete the test parameter comparison and acceptance in the power platform test. The present invention can complete the power distribution test without any hardware modification and accessory equipment purchase. In addition, the reduction of the waiting time for the power platform will not affect other tests.

[0050] Taking Hainan Changjiang Nuclear Power Plant as an example, according to relevant design requirements, the power plant has three power platforms in the process of physical startup test of the core refueling, namely 50% FP, 75% FP and 100% FP. The first two power platforms can effectively shorten the waiting time by a total of 48 hours, which has obvious optimization effect on the overall startup physical test process and can significantly improve the reactor core load factor. It is preliminarily estimated that the economic benefits will increase by about 10 million yuan.

[0051] The simulation process of core fine power distribution is as follows:

[0052] (1) Simulating the reactor power distribution test process, after completing the simulated core power increase to reach the target power platform, calculate the core power distribution after a preset waiting time X, and obtain the theoretical values ​​of the core key parameters based on the core power distribution calculation;

[0053] (2) Simulate the core power increase process, enter the next power platform test simulation, complete the theoretical calculation of the core key parameters under all power platforms, and obtain the core theoretical database of the test process.

[0054] The core fine power distribution simulation calculates the flux distribution and power distribution of each core block in the three-dimensional core by considering the fuel burnup and the short half-life high absorption cross-section nuclide burnup.

[0055] The simulation calculation formula for fuel burnup is as follows:

[0056]

[0057] Among them, N i represents the nucleon density of the ith nuclide; n represents the total number of nuclides in the system; β represents the reaction coefficient between nuclides, including decay, fission and capture reaction processes; β j→i represents the reaction rate of the jth nuclide to generate the i-th nuclide, β i represents the disappearance rate of the ith nuclide; N j (0) represents the nucleon density of the jth nuclide at time 0; N 0,j represents the nucleon density of the jth nuclide at the initial moment.

[0058] The short half-life high absorption cross-section nuclide burnup includes iodine nuclide burnup and xenon nuclide burnup.

[0059] The simulation calculation formula for iodine nuclide burnup is as follows:

[0060]

[0061] Among them, N I (t) represents the nuclear density of iodine at time t; γ I represents the fission share of iodine; Σ f represents the fission cross section; φ(t) represents the neutron flux at time t; λ I represents the decay constant of iodine.

[0062] The simulation calculation formula for xenon nuclide burnup is as follows:

[0063]

[0064] Among them, N Xe (t) represents the nucleon density at xenon t; γ Xe represents the fission fraction of xenon; Σ f represents the fission cross section; φ(t) represents the neutron flux at time t; λ I represents the decay constant of iodine; N I (t) represents the nuclear density of iodine at time t; λ Xe represents the decay constant of xenon; σ a,Xe represents the microscopic absorption cross section of xenon.

[0065] Taking the core of Hualong One (a million-kilowatt nuclear power plant reactor core consisting of 177 fuel assemblies) as an example, the typical core loading method in this example is as follows: Figure 3 As shown in FIG. 1 , the core theoretical current value at the time of the reactor self-sufficiency detector and the time of stabilization for 24 hours when the power platform is increased from 0% FP to 50% FP at a power increase rate of 3% FP / min is obtained by simulation, and then the core theoretical database is obtained at the time of just reaching 50% FP and after stabilization for 24 hours by simulation of the engineering design software package (SCIENCE V2). The core flux diagram measurement results of the 50% FP power platform are established by using the method of the present invention and the traditional method respectively, and the component power distribution is compared. Figure 4 The fuel assembly power distribution deviation calculated by the traditional method and the method of this application is shown in Figure 5 and Figure 6 The relevant test acceptance results are shown in Table 1. It can be seen that the acceptance items of the method given in the present invention and the traditional method meet the acceptance criteria and can meet the requirements of the flux diagram test. In addition, the calculation results of the method used in the present invention are more conservative than those of the traditional method, which can ensure that the safety of the core is met.

[0066] Table 1 Examples of flux diagram test results under typical conditions

[0067]

[0068] Embodiment 2: Reactor power distribution test system based on in-core self-powered detector, the system is used to implement the reactor power distribution test based on in-core self-powered detector recorded in Embodiment 1, such as Figure 2 As shown, it includes a simulation module, a measurement module, a reconstruction module and a verification module.

[0069] Among them, the simulation module is used to use the three-dimensional core fine power distribution calculation software to simulate the core fine power distribution under various transient states, and then establish the core theoretical database, and use the coupling coefficient method to establish the coupling coefficient of each node in each fuel assembly; the measurement module is used to obtain the fixed and discrete measured current data collected by the in-core self-powered detector, and use the high-order fitting method to expand it to obtain the continuous power distribution information; the reconstruction module is used to use the online power distribution expansion software to expand the measured power distribution of the whole stack based on the coupling coefficient and continuous power distribution information; the verification module is used to compare the core fine power distribution under transient state with the measured power distribution of the whole stack to obtain the power distribution deviation test results.

[0070] Working principle: The present invention adopts a high-precision core calculation program to theoretically ensure that the theoretical state is consistent with the measured core state when the xenon equilibrium state is not reached, avoiding parameter over-limit and additional test operations caused by the inconsistency between the theoretical database and the measured state; for my country's existing pressurized water reactor nuclear power plants, the technology recorded in the present invention only needs to use the existing hardware design to measure the core parameters, and through the automated power distribution test device proposed by the present invention, the theoretical key parameter calculation and theoretical database generation of the core state at any time are completed through the simulation module. The reconstruction module combines the measured data in the pile with the high-precision power distribution expansion program to obtain the measured power distribution in the pile, and the measured key parameters in the pile are calculated from the measured power distribution; the comparison between the theoretical value and the measured value of the key parameters of the core is completed through the verification module, and the power distribution test of the power-raising platform at any time is realized.

[0071] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0072] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0073] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0074] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0075] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A reactor power distribution test method based on an in-core self-powered detector, characterized in that: The following steps are involved: The core theoretical database is established by simulating the core fine power distribution under various transient conditions using the three-dimensional core fine power distribution calculation software, and the coupling coefficient of each node in each fuel assembly is established using the coupling coefficient method; Obtain fixed and discrete measured current data collected by the in-pile self-powered detector, and use high-order fitting methods to expand it to obtain continuous power distribution information; Based on the coupling coefficient and continuous power distribution information, the online power distribution expansion software is used to expand the measured power distribution of the whole reactor; The precise power distribution of the core under transient conditions is compared with the measured power distribution of the entire reactor to obtain the power distribution deviation test results; The core fine power distribution simulation calculates the flux distribution and power distribution of each core node in the three-dimensional core by considering the fuel burnup and the short half-life high absorption cross-section nuclide burnup; The simulation calculation formula of the fuel consumption is specifically: Among them, N i represents the nucleon density of the ith nuclide; n represents the total number of nuclides in the system; β represents the reaction coefficient between nuclides, including decay, fission and capture reaction processes; β j→i represents the reaction rate of the jth nuclide to generate the i-th nuclide, β i represents the disappearance rate of the ith nuclide; N j (0) represents the nucleon density of the jth nuclide at time 0; N 0,j represents the nucleon density of the jth nuclide at the initial moment; The short half-life high absorption cross-section nuclide burnup includes iodine nuclide burnup and xenon nuclide burnup; The simulation calculation formula of the iodine nuclide burnup is specifically: Among them, N I (t) represents the nuclear density of iodine at time t; γ I represents the fission share of iodine; Σ f represents the fission cross section; φ(t) represents the neutron flux at time t; λ I represents the decay constant of iodine; The simulation calculation formula of the xenon nuclide burnup is specifically: Among them, N Xe (t) represents the nucleon density at xenon t; γ Xe represents the fission fraction of xenon; Σ f represents the fission cross section; φ(t) represents the neutron flux at time t; λ I represents the decay constant of iodine; N I (t) represents the nuclear density of iodine at time t; λ Xe represents the decay constant of xenon; σ a,Xe represents the microscopic absorption cross section of xenon.

2. The reactor power distribution test method based on the in-core self-powered detector according to claim 1 is characterized in that: The simulation process of the core fine power distribution is specifically as follows: During the simulation of the reactor power distribution test process, after the simulated core power rise reaches the target power platform, the core power distribution is calculated after the preset waiting time X, and the theoretical values ​​of the core key parameters are obtained based on the core power distribution calculation; The core power increase process is simulated, and the next power platform test simulation is entered. The theoretical calculation of the key parameters of the core under all power platforms is completed to obtain the core theoretical database of the test process.

3. Reactor power distribution test system based on in-core self-powered detector, characterized by: The system is used to implement the reactor power distribution test method based on the in-core self-powered detector as claimed in claim 1 or 2, comprising: The simulation module is used to establish a core theoretical database after simulating the core fine power distribution under various transient states using a three-dimensional core fine power distribution calculation software, and to establish the coupling coefficient of each node in each fuel assembly using a coupling coefficient method; The measurement module is used to obtain fixed and discrete measured current data collected by the in-pile self-powered detector, and expand it to obtain continuous power distribution information using a high-order fitting method; The reconstruction module is used to obtain the measured power distribution of the whole reactor based on the coupling coefficient and continuous power distribution information by using the online power distribution expansion software; The verification module is used to compare the core fine power distribution under transient conditions with the measured power distribution of the entire reactor to obtain the power distribution deviation test results.

4. A computer terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the reactor power distribution test method based on the in-core self-powered detector is implemented as described in any one of claims 1-2.

5. A computer readable medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the reactor power distribution test method based on the in-core self-powered detector as described in any one of claims 1-2.

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