Nuclear power plant reactor core fuel assembly fission product nuclide online monitoring method and system

Abstract

The invention discloses a nuclear power plant reactor core fuel assembly fission product nuclide online monitoring method and system, and the method comprises the following steps: making an energy scale based on an actual measurement single spectrum of a nuclear power plant reactor core fuel assembly fission product nuclide, and obtaining each theoretical deposition single spectrum; all the theoretical deposition energy single spectrums are corrected and superposed, and a theoretical deposition combined spectrum is obtained; and calculating the theoretical deposition spectrum through a preset algorithm to obtain an activity value of the nuclide, thereby realizing online monitoring of the fission product nuclide of the reactor core fuel assembly of the nuclear power plant. According to the invention, the spectrum drift in the actually measured single spectrum is corrected in real time, and the activity detection of the fission product nuclide, especially the nuclide with low energy segment content, of the nuclear power plant reactor core fuel assembly is realized.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and in particular to an online monitoring method and system for fission product nuclides of a core fuel assembly of a nuclear power plant. Background Art

[0002] During long-term operation in a reactor, hydrogenation or wear can cause early cracks in the fuel cladding. Fission product nuclides within the cladding can be released into the primary coolant through these cracks, leading to elevated radioactivity levels in the coolant. If these early small cracks are not detected promptly, they can deteriorate into large or multiple cracks due to secondary hydrogenation, compromising reactor operational safety and personnel radiation safety. After long-term operation, when early, tiny cracks in the fuel cladding occur, the small amounts of fission product nuclides (such as Xe-133, Xe-135, I-131, and Kr-85m) released are significantly affected by the presence of large amounts of activation products and Compton scattering in the pipe inner wall or primary cooling water. Low-energy nuclide characteristic peaks are superimposed on the background. Incomplete background subtraction from the low-energy region of the gamma-ray spectrum can affect the extraction of parameters for these superimposed characteristic peaks, particularly when the low-energy nuclide concentration in the measured object is low, which can affect activity analysis of the low-energy nuclides.

[0003] In order to increase the efficiency of energy spectrum analysis of low-concentration and low-energy target nuclides released in the early stage of fuel damage, when acquiring gamma spectrum data for nuclides with relatively low concentrations, the more accumulated measurement counts, the better the statistics. Under a certain counting rate, the longer the measurement time, the better the statistics. However, due to the influence of factors such as ambient temperature, power supply, electronic system, aging, radiation, vibration, humidity and power supply noise, the spectrometer system parameters are always changing, causing the characteristic peak position of the target nuclide or the entire spectrum line to drift continuously during the measurement process, ultimately leading to broadening of the spectrum line measured for a long time, reduced energy resolution of the gamma spectrum, and the characteristic peak of the low-energy target nuclide in the superimposed spectrum may still be weak, resulting in inaccurate energy spectrum analysis and inaccurate online monitoring of fission product nuclides in the core fuel assemblies of nuclear power plants. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that, in response to at least one defect of the related technology mentioned in the above background technology: the peak shape of the characteristic peak of the fission product nuclides of the nuclear power plant core fuel assembly drifts during the measurement process, resulting in a decrease in the energy resolution of the γ energy spectrum, and the characteristic peak of the nuclides in the low energy segment of the superposition spectrum is weak, resulting in inaccurate energy spectrum analysis, thereby leading to inaccurate online monitoring of the fission product nuclides of the nuclear power plant core fuel assembly. Provided is a method and system for online monitoring of the fission product nuclides of the nuclear power plant core fuel assembly.

[0005] The technical solution adopted by the present invention to solve the technical problem is to construct an online monitoring method for fission product nuclides of a nuclear power plant core fuel assembly, the method comprising the following steps:

[0006] Based on the measured single spectrum of fission product nuclides in nuclear power plant core fuel assemblies, the energy calibration is carried out to obtain the theoretical deposition single spectrum.

[0007] All theoretical deposition energy single spectra are corrected and superimposed to obtain the theoretical deposition composite spectrum;

[0008] The theoretical deposition spectrum is calculated using a preset algorithm to obtain the activity value of the nuclide, thereby realizing online monitoring of the fission product nuclides in the core fuel assembly of a nuclear power plant.

[0009] In some embodiments, energy calibration is performed based on a measured spectrum of fission product nuclides in a nuclear power plant core fuel assembly to obtain a theoretical deposition spectrum, including:

[0010] Based on the measured single spectra of fission product nuclides in the core fuel assembly of a nuclear power plant, the channel addresses of each measured single spectrum are converted into energy calibration parameters to obtain each theoretical deposition single spectrum;

[0011] The formula for converting the channel address of each measured single spectrum into energy calibration parameters is: in, is the energy scale parameter of the ith theoretical deposition spectrum, is the track address of the ith measured single spectrum, i is the ith theoretical deposition single spectrum, and a, b, and c are conversion factors.

[0012] In some embodiments, all theoretical single deposition spectra are corrected and superimposed to obtain theoretical combined deposition spectra, including:

[0013] Correcting each theoretical deposition spectrum corresponding to the measured single spectrum according to the counting compensation factor corresponding to each measured single spectrum to obtain corrected theoretical deposition spectrum;

[0014] All corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum.

[0015] In some embodiments, the count compensation factor corresponding to each measured single spectrum is obtained by performing dead time correction on the dead time corresponding to each measured single spectrum;

[0016] The formula for calculating the counting compensation factor corresponding to each measured single spectrum is: Among them, W i is the counting compensation factor corresponding to the ith theoretical deposition spectrum, i is the ith theoretical deposition spectrum, N all is the total value of the whole spectrum, t is the total measurement time, t dead To measure dead time.

[0017] In some embodiments, the measurement dead time corresponding to each measured single spectrum is obtained by subtracting the measurement live time corresponding to each measured single spectrum from the measurement total time corresponding to each measured single spectrum; and / or

[0018] The total measurement time corresponding to each measured single spectrum is calculated by the background counting rate and the nuclide counting rate.

[0019] In some embodiments, the number of all corrected theoretical deposition single spectra is the number of all theoretical deposition single spectra, and the number of all theoretical deposition single spectra is calculated by the total measurement time of the measured single spectra.

[0020] In some embodiments, all corrected theoretical deposition single spectra are linearly superimposed to obtain a theoretical deposition composite spectrum, including:

[0021] The count values of each energy point of all corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum.

[0022] In some embodiments, the count values of each energy point of all corrected theoretical deposition single spectra are linearly superimposed to obtain a theoretical deposition composite spectrum, including:

[0023] Perform linear superposition on the count values of the same energy point in all corrected theoretical deposition single spectra;

[0024] The count values corresponding to different energy points in all corrected theoretical deposition single spectra are obtained by a preset algorithm, and linear superposition is performed to obtain the theoretical deposition composite spectrum.

[0025] In some embodiments, the activity value of a nuclide is calculated from a theoretical deposition spectrum using a preset algorithm to achieve online monitoring of fission product nuclides in a nuclear power plant core fuel assembly, including:

[0026] The standard peak shape closest to the theoretical deposition spectrum peak shape is selected to perform peak shape fitting on the theoretical deposition spectrum, and the activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape to realize online monitoring of fission product nuclides in nuclear power plant core fuel assemblies.

[0027] The present invention also constructs an online monitoring system for fission product nuclides of a nuclear power plant core fuel assembly, comprising:

[0028] Energy calibration module, used to perform energy calibration based on the measured single spectrum of each nuclide in the nuclear reactor to obtain each theoretical deposition single spectrum;

[0029] A correction superposition module is used to correct and superpose all theoretical deposition energy single spectra to obtain a theoretical deposition composite spectrum; and

[0030] The activity value calculation module is used to calculate the theoretical deposition spectrum through a preset algorithm to obtain the activity value of the nuclide to realize the online monitoring of the fission product nuclides in the core fuel assembly of the nuclear power plant.

[0031] By implementing the present invention, the following beneficial effects are achieved:

[0032] The present invention uses the measured single spectrum of fission product nuclides of nuclear power plant core fuel assemblies as energy calibration to obtain various theoretical deposition single spectra, corrects the spectrum drift in the measured single spectrum in real time, then corrects and superimposes all the theoretical deposition energy single spectra to obtain a theoretical deposition composite spectrum, and finally calculates the theoretical deposition composite spectrum through a preset algorithm to obtain the activity value of the nuclide, thereby realizing online monitoring of fission product nuclides of nuclear power plant core fuel assemblies, especially online monitoring of fission product nuclides of nuclear power plant core fuel assemblies with low content in the low energy range. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0034] Figure 1 A flow chart of an embodiment of the method for online monitoring of fission product nuclides in a core fuel assembly of a nuclear power plant according to the present invention is shown;

[0035] Figure 2 The figure shows a measured single spectrum of channel addresses and count values before energy calibration in an embodiment of the on-line monitoring method for fission product nuclides of a nuclear power plant core fuel assembly according to the present invention;

[0036] Figure 3 The figure shows the energy calibration parameter-count value theoretical deposition single spectrum after energy calibration in one embodiment of the on-line monitoring method for fission product nuclides of a nuclear power plant core fuel assembly according to the present invention;

[0037] Figure 4 The figure shows the standard peak shape of the energy point E=6134keV in one embodiment of the on-line monitoring method for fission product nuclides of a nuclear power plant core fuel assembly according to the present invention;

[0038] Figure 5 The figure shows the standard peak shape of the energy point E=1174keV in one embodiment of the on-line monitoring method for fission product nuclides of a nuclear power plant core fuel assembly according to the present invention;

[0039] Figure 6 The figure shows the standard peak shape of the energy point E=511keV in one embodiment of the on-line monitoring method for fission product nuclides of a nuclear power plant core fuel assembly according to the present invention. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0041] It should be noted that the flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all content and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0042] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0043] Typically, the energy spectrum measured over a long period of time is a corrected superposition of multiple single spectra measured over a short period of time. However, during actual measurements, each of the individual spectra exhibits a certain degree of spectral drift, resulting in energy shifts corresponding to their channel addresses. Energy calibration correction is required for the gamma spectrum measured over a short period of time based on changes in the reference peak position. To address the spectral drift during long-term spectral acquisition of low-concentration, low-energy target nuclides released early from fuel assembly cladding failure, spectrum stabilization is primarily achieved by adjusting spectrometer system parameters, such as the high-voltage power supply and amplifier gain. However, because the energy spectrum generated by the detector is susceptible to interference from factors such as temperature and high pressure, the primary coolant spectrum often drifts. Conventional gain stabilization or reference peak stabilization methods only adjust the gain deviation of the energy calibration curve. Alternatively, real-time peak search and peak shape fitting can be performed based on the characteristic peaks of radionuclides in the gamma spectrum. Spectral stabilization can be achieved by dynamically changing the boundary function under adjusted calibration parameters. This method has the advantages of low cost, short processing time, high efficiency, and the lack of hardware. However, it requires fitting the peak shapes of at least two uninterrupted characteristic peaks, making it susceptible to the effects of overlapping peaks. Furthermore, to address the problem of low-energy target nuclides being easily overwhelmed in the superimposed spectrum, mathematical functions (such as polynomials and exponential functions) are often used to fit the background spectrum. However, selecting an appropriate fitting function is challenging, especially for complex spectra such as those of low-energy, low-concentration target nuclides. A poor fit can introduce errors. Furthermore, it can be inaccurate in low-count regions, affecting the results.

[0044] like Figure 1 As shown, some embodiments of the present invention disclose a method for online monitoring of fission product nuclides in a core fuel assembly of a nuclear power plant, the method comprising the following steps:

[0045] Based on the measured single spectrum of fission product nuclides in nuclear power plant core fuel assemblies, the energy calibration is carried out to obtain the theoretical deposition single spectrum.

[0046] All theoretical deposition energy single spectra are corrected and superimposed to obtain the theoretical deposition composite spectrum;

[0047] The theoretical deposition spectrum is calculated using a preset algorithm to obtain the activity value of the nuclide, thereby realizing online monitoring of the fission product nuclides in the core fuel assembly of a nuclear power plant.

[0048] The present invention uses the measured single spectrum of fission product nuclides of nuclear power plant core fuel assemblies as energy calibration, corrects the spectrum drift in the measured single spectrum in real time, and accurately calculates the activity of low-content nuclides in the low-energy range by calculating the theoretical deposition composite spectrum.

[0049] like Figures 2 to 3 As shown, in some embodiments, energy calibration is performed based on the measured single spectrum of fission product nuclides of the nuclear power plant core fuel assembly to obtain a theoretical deposition single spectrum, including:

[0050] Based on the measured single spectrum of fission product nuclides in the core fuel assembly of a nuclear power plant, the channel addresses of each measured single spectrum are converted into energy calibration parameters to obtain each theoretical deposition single spectrum;

[0051] The formula for converting the channel address of each measured single spectrum into energy calibration parameters is: +c, where is the energy scale parameter of the ith theoretical deposition spectrum, is the channel address of the ith measured single spectrum, i is the ith theoretical deposition single spectrum, and a, b, and c are conversion factors.

[0052] The characteristic peaks of nuclides such as Na-24, Co-60, Co-58, Ag-110m, Zr-95, Nb-95, and Sb-124 inherent in the primary coolant of a nuclear reactor are used as references for automatic energy calibration of each measured single spectrum, and energy calibration is performed on each measured single spectrum. Specifically, a gamma-ray standard source with a constant energy calibration parameter, such as Cs-137 (661.7 keV) and Co-60 (1173.2 keV and 1332.5 keV), is used to obtain the channel addresses of at least three energy calibration parameters, establish a nonlinear relationship between the energy calibration parameters and the channel addresses, and determine the conversion factors a, b, and c by polynomial fitting, for example, a = 3.089×10 -8 , b=3.081×10 -1 , c=2.159×10 -1 Among them, Cs-137 (661.7keV), Co-60 (1173.2keV and 1332.5keV) and a=3.089×10 -8 , b=3.081×10 -1 , c=2.159×10 -1 This is just an example and is not intended to limit the present application. Other examples are possible.

[0053] In some embodiments, all theoretical single deposition spectra are corrected and superimposed to obtain theoretical combined deposition spectra, including:

[0054] Correcting each theoretical deposition spectrum corresponding to the measured single spectrum according to the counting compensation factor corresponding to each measured single spectrum to obtain corrected theoretical deposition spectrum;

[0055] All corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum.

[0056] The calculation formula for correcting and superimposing all theoretical deposition single spectra is: Among them, E p is the theoretical sedimentation spectrum, is the energy scale parameter of the ith theoretical deposition spectrum, W i is the counting compensation factor corresponding to the i-th theoretical deposition single spectrum, and i is the i-th theoretical deposition single spectrum.

[0057] In some embodiments, the count compensation factor corresponding to each measured single spectrum is obtained by performing dead time correction on the dead time corresponding to each measured single spectrum;

[0058] The formula for calculating the counting compensation factor corresponding to each measured single spectrum is: Among them, W i is the counting compensation factor corresponding to the ith theoretical deposition spectrum, i is the ith theoretical deposition spectrum, N all is the total value of the whole spectrum, t is the total measurement time, t dead To measure dead time.

[0059] Due to the existence of dead time, the signal finally recorded by the detector system will be less than the actual event, that is, missed counts will occur. This phenomenon is inevitable. The only way is to perform dead time correction on the total value of the full spectrum actually detected and calculate the count compensation factor W of each theoretical deposition single spectrum. i Among them, N all is the total value of the whole spectrum, i.e. the sum of the count values of all channels; dead To measure the dead time, that is, the time required to recover to be able to process the next pulse signal after processing a pulse signal. During this period of time, the detector cannot receive new signals, so the counting value will be lost.

[0060] In some embodiments, the measurement dead time corresponding to each measured single spectrum is obtained by subtracting the measurement live time corresponding to each measured single spectrum from the measurement total time corresponding to each measured single spectrum; and / or

[0061] The total measurement time corresponding to each measured single spectrum is calculated by the background counting rate and the nuclide counting rate.

[0062] The calculation formula for the measured dead time corresponding to each measured single spectrum is: t dead =tt live , where tlive To measure live time, the live time is the period of time during which the detector can effectively receive and process signals.

[0063] For low-activity nuclides, it is necessary to ensure that the nuclide counting rate is significantly higher than the background counting rate, that is, the total measurement time of the measured single spectrum. Determine a total measurement time of the measured single spectrum that meets the statistics of the nuclide characteristic peak. The calculation formula for the total measurement time corresponding to each measured single spectrum is: Among them, R Background is the background count rate, R Signal is the counting rate of each nuclide, 3.29 is an empirical value, 3.29 is only an example here, and is not intended to limit the present application, and may be other.

[0064] In some embodiments, the number of all corrected theoretical deposition single spectra is the number of all theoretical deposition single spectra, and the number of all theoretical deposition single spectra is calculated by the total measurement time of the measured single spectra.

[0065] The number of all theoretical deposition single spectra is calculated as: Where n is the number of all corrected theoretical deposition spectra. If n is a non-integer, it is rounded up. Pre is the expected value of the lower limit of characteristic nuclide detection, t is the total measurement time corresponding to each measured single spectrum, ε is the efficiency, γ is the nuclide branching ratio, B is the background count value, 2.71 and 4.66 are empirical values, 2.71 and 4.66 are only examples here and are not intended to limit the present application, and can also be other.

[0066] In some embodiments, all corrected theoretical deposition single spectra are linearly superimposed to obtain a theoretical deposition composite spectrum, including:

[0067] The count values of each energy point of all corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum.

[0068] In some embodiments, the count values of each energy point of all corrected theoretical deposition single spectra are linearly superimposed to obtain a theoretical deposition composite spectrum, including:

[0069] Perform linear superposition on the count values of the same energy point in all corrected theoretical deposition single spectra;

[0070] The count values corresponding to different energy points in all corrected theoretical deposition single spectra are obtained by a preset algorithm, and linear superposition is performed to obtain the theoretical deposition composite spectrum.

[0071] Specifically, based on the consistency of the energy points, the count values of the energy points with the same energy at different addresses in all the corrected theoretical deposition single spectra are linearly superimposed; the interpolation method is used to obtain the corresponding count values of the energy points with different energies in all the corrected theoretical deposition single spectra, and linear superposition is performed to obtain the theoretical deposition composite spectrum.

[0072] like Figures 4 to 6 As shown, in some embodiments, the activity value of the nuclide is obtained by calculating the theoretical deposition spectrum using a preset algorithm to achieve online monitoring of the fission product nuclides in the core fuel assembly of a nuclear power plant, including:

[0073] The standard peak shape closest to the theoretical deposition spectrum peak shape is selected to perform peak shape fitting on the theoretical deposition spectrum, and the activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape to realize online monitoring of fission product nuclides in nuclear power plant core fuel assemblies.

[0074] A method for calculating the net peak area of weak peaks under high interference conditions based on the preset nuclide library is used. That is, the preset nuclide library is used to guide the automatic selection of the closest standard peak shape in the preset nuclide library to perform peak shape fitting on the theoretical deposition spectrum. The noise of activated corrosion products can be stripped off to calculate the net peak area, and the activity value of the nuclide can be accurately calculated.

[0075] For example, this embodiment provides a method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly. This method is only an example and is not intended to limit the present application. Other methods are also possible. The specific steps are as follows:

[0076] When this method was applied to the cladding damage detection of nuclear power plant fuel assemblies, during the measurement of fission product nuclides in the primary coolant, it was found that the counting rate of the target nuclide Xe-133 was 60cps. The total time t for the actual single spectrum measurement is 10 minutes. In order to find the abnormal phenomenon of early damage of fuel assembly cladding as early as possible, according to the engineering requirements, the detection limit of the characteristic nuclide of Xe-133 nuclide is expected to be MDA. Pre is 10 7 Bq / m 3 , based on the expected value of the lower detection limit of the characteristic nuclide of the nuclide The number of all theoretical deposition single spectra is calculated to be 16. Then, the characteristic peaks of Co-58, Ag-110m, and Zr-95 nuclides are used as references for the automatic energy scale of each measured single spectrum, and the influence of peak drift is corrected in real time. Convert all measured single spectrum addresses into energy scale parameters, that is, invert the measured single spectrum into the theoretical deposition single spectrum of the ray in the detector, and then consider the measurement dead time influence of each theoretical deposition single spectrum. Calculate the counting compensation factor W corresponding to the i-th theoretical deposition spectrum i , and according to The theoretical deposition spectrum was formed by superimposing the theoretical deposition spectrum with dead time compensation correction. Finally, the weak peak net peak area calculation method under high interference conditions guided by the preset nuclide library was used to calculate the Xe-133 background count rate to be 1.6 cps and the net count rate to be 130 cps. The activity concentration of Xe-133 was accurately calculated to be 2.5×10 7 Bq / m 3 , exceeding the early damage limit of the fuel assembly cladding.

[0077] The present invention adopts a time-sharing spectrum stabilization method using energy scale for automatic energy calibration, an adaptive linear superposition method based on a dead time counting compensation factor, and a weak peak net peak area calculation method under high interference conditions guided by a preset nuclide library, thereby realizing online monitoring of fission product nuclides in the core fuel assembly of a nuclear power plant. In particular, by correcting the influence of spectrum drift on the theoretical deposition single spectrum acquisition of long-term weak peaks, the background of weak peaks in the low-energy segment is accurately calculated, the online monitoring of weak fission product nuclides in the primary coolant is improved, the efficiency of theoretical deposition single spectrum analysis of low-concentration, low-energy segment nuclides released by fuel damage is increased, and early damage to the fuel assembly cladding is discovered earlier.

[0078] Some embodiments of the present invention disclose an online monitoring system for fission product nuclides in a core fuel assembly of a nuclear power plant, comprising:

[0079] Energy calibration module, used to perform energy calibration based on the measured single spectrum of each nuclide in the nuclear reactor to obtain each theoretical deposition single spectrum;

[0080] A correction superposition module is used to correct and superpose all theoretical deposition energy single spectra to obtain a theoretical deposition composite spectrum; and

[0081] The activity value calculation module is used to calculate the theoretical deposition spectrum through a preset algorithm to obtain the activity value of the nuclide to realize the online monitoring of the fission product nuclides in the core fuel assembly of the nuclear power plant.

[0082] In some embodiments, the method for performing energy calibration based on the measured single spectrum of each nuclide in the nuclear reactor to obtain each theoretical deposition single spectrum includes:

[0083] Based on the measured single spectrum of fission product nuclides in the core fuel assembly of a nuclear power plant, the channel addresses of each measured single spectrum are converted into energy calibration parameters to obtain each theoretical deposition single spectrum;

[0084] The formula for converting the channel address of each measured single spectrum into energy calibration parameters is: in, is the energy scale parameter of the ith theoretical deposition spectrum, is the channel address of the ith measured single spectrum, i is the ith theoretical deposition single spectrum, and a, b, and c are conversion factors.

[0085] In some embodiments, the correction overlay module includes:

[0086] a correction unit, configured to correct each theoretical deposition spectrum corresponding to the measured single spectrum according to a counting compensation factor corresponding to each measured single spectrum, to obtain each corrected theoretical deposition spectrum;

[0087] The superposition unit is used to linearly superpose all the corrected theoretical deposition single spectra to obtain the theoretical deposition composite spectrum.

[0088] The calculation formula for correcting and superimposing all theoretical deposition single spectra is: Among them, E p is the theoretical sedimentation spectrum, is the energy scale parameter of the ith theoretical deposition spectrum, W i is the counting compensation factor corresponding to the i-th theoretical deposition single spectrum, and i is the i-th theoretical deposition single spectrum.

[0089] In some embodiments, the count compensation factor corresponding to each measured single spectrum is obtained by performing dead time correction on the dead time corresponding to each measured single spectrum;

[0090] The formula for calculating the counting compensation factor corresponding to each measured single spectrum is: Among them, W i is the counting compensation factor corresponding to the ith theoretical deposition spectrum, i is the ith theoretical deposition spectrum, N all is the total value of the whole spectrum, t is the total measurement time, t dead To measure dead time.

[0091] In some embodiments, the measurement dead time corresponding to each measured single spectrum is obtained by subtracting the measurement live time corresponding to each measured single spectrum from the measurement total time corresponding to each measured single spectrum; and / or

[0092] The total measurement time corresponding to each measured single spectrum is calculated by the background counting rate and the nuclide counting rate.

[0093] The calculation formula for the measured dead time corresponding to each measured single spectrum is: t dead =tt live , where t live To measure live time, the live time is the period of time during which the detector can effectively receive and process signals.

[0094] For low-activity nuclides, it is necessary to ensure that the nuclide counting rate is significantly higher than the background counting rate, that is, the total measurement time of the measured single spectrum. Determine a total measurement time of the measured single spectrum that meets the statistics of the nuclide characteristic peak. The calculation formula for the total measurement time corresponding to each measured single spectrum is: Among them, R Background is the background count rate, R Signal is the counting rate of each nuclide, 3.29 is an empirical value, 3.29 is only an example here, and is not intended to limit the present application, and may be other.

[0095] In some embodiments, the number of all corrected theoretical deposition single spectra is the number of all theoretical deposition single spectra, and the number of all theoretical deposition single spectra is calculated by the total measurement time of the measured single spectra.

[0096] The number of all theoretical deposition single spectra is calculated as: Where n is the number of all corrected theoretical deposition spectra. If n is a non-integer, it is rounded up. Pre is the expected value of the lower limit of characteristic nuclide detection, t is the total measurement time corresponding to each measured single spectrum, ε is the efficiency, γ is the nuclide branching ratio, B is the background count value, 2.71 and 4.66 are empirical values, 2.71 and 4.66 are only examples here and are not intended to limit the present application, and can also be other.

[0097] In some embodiments, all corrected theoretical deposition single spectra are linearly superimposed to obtain a theoretical deposition composite spectrum, including:

[0098] The count values of each energy point of all corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum.

[0099] In some embodiments, the superimposing unit includes:

[0100] The same energy point superposition subunit is used to linearly superpose the count values of the same energy points in all corrected theoretical deposition single spectra;

[0101] The different energy point superposition subunit is used to obtain the counting values corresponding to different energy points in all the corrected theoretical deposition single spectra through a preset algorithm, and perform linear superposition to obtain the theoretical deposition composite spectrum.

[0102] In some embodiments, the activity value of a nuclide is calculated from a theoretical deposition spectrum using a preset algorithm to achieve online monitoring of fission product nuclides in a nuclear power plant core fuel assembly, including:

[0103] The standard peak shape closest to the theoretical deposition spectrum peak shape is selected to perform peak shape fitting on the theoretical deposition spectrum, and the activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape to realize online monitoring of fission product nuclides in nuclear power plant core fuel assemblies.

[0104] It is understandable that the above embodiments only express some of the implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above embodiments or technical features can be freely combined, and several deformations and improvements can be made, which all fall within the scope of protection of the present invention, that is, the embodiments described in "some embodiments" can be freely combined with any of the above and below embodiments. Therefore, all equivalent transformations and modifications made to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly, characterized in that: The method comprises the following steps: Based on the measured single spectrum of fission product nuclides in nuclear power plant core fuel assemblies, the energy calibration is carried out to obtain the theoretical deposition single spectrum. All theoretical deposition energy single spectra are corrected and superimposed to obtain the theoretical deposition composite spectrum; The theoretical deposition spectrum is calculated using a preset algorithm to obtain the activity value of the nuclide, thereby realizing online monitoring of the fission product nuclides in the core fuel assembly of a nuclear power plant.

2. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 1, characterized in that: Based on the measured single spectrum of fission product nuclides in nuclear power plant core fuel assemblies for energy calibration, the theoretical deposition single spectrum is obtained, including: Based on the measured single spectra of fission product nuclides in the core fuel assembly of a nuclear power plant, the channel addresses of each measured single spectrum are converted into energy calibration parameters to obtain each theoretical deposition single spectrum; The formula for converting the channel address of each measured single spectrum into energy calibration parameters is: +c, where is the energy scale parameter of the ith theoretical deposition spectrum, is the track address of the ith measured single spectrum, i is the ith theoretical deposition single spectrum, and a, b, and c are conversion factors.

3. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 1, characterized in that: All theoretical deposition single spectra are corrected and superimposed to obtain the theoretical deposition composite spectra, including: Correcting each theoretical deposition spectrum corresponding to the measured single spectrum according to the counting compensation factor corresponding to each measured single spectrum to obtain corrected theoretical deposition spectrum; All corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum.

4. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 3, characterized in that: The counting compensation factor corresponding to each measured single spectrum is obtained by performing dead time correction on the dead time corresponding to each measured single spectrum; The formula for calculating the counting compensation factor corresponding to each measured single spectrum is: Among them, W i is the counting compensation factor corresponding to the ith theoretical deposition spectrum, i is the ith theoretical deposition spectrum, N all is the total value of the whole spectrum, t is the total measurement time, t dead To measure dead time.

5. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 4, characterized in that: The measurement dead time corresponding to each measured single spectrum is obtained by subtracting the measurement live time corresponding to each measured single spectrum from the total measurement time corresponding to each measured single spectrum; and / or The total measurement time corresponding to each measured single spectrum is calculated by the background counting rate and the nuclide counting rate.

6. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 3, characterized in that: The number of all corrected theoretical deposition single spectra is the number of all theoretical deposition single spectra, and the number of all theoretical deposition single spectra is calculated by the total measurement time of the measured single spectra.

7. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 3, characterized in that: All corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum, including: The count values of each energy point of all corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum.

8. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 7, characterized in that: The count values of each energy point of all corrected theoretical deposition single spectra are linearly superimposed to obtain the theoretical deposition composite spectrum, including: Perform linear superposition on the count values of the same energy point in all corrected theoretical deposition single spectra; The count values corresponding to different energy points in all corrected theoretical deposition single spectra are obtained by a preset algorithm, and linear superposition is performed to obtain the theoretical deposition composite spectrum.

9. The method for online monitoring of fission product nuclides in a nuclear power plant core fuel assembly according to claim 1, characterized in that: The theoretical deposition spectrum is calculated using a preset algorithm to obtain the activity value of the nuclide, enabling online monitoring of fission product nuclides in nuclear power plant core fuel assemblies, including: The standard peak shape closest to the theoretical deposition spectrum peak shape is selected to perform peak shape fitting on the theoretical deposition spectrum, and the activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape to realize online monitoring of fission product nuclides in nuclear power plant core fuel assemblies.

10. An online monitoring system for fission product nuclides in a nuclear power plant core fuel assembly, characterized in that: include: Energy calibration module, used to perform energy calibration based on the measured single spectrum of each nuclide in the nuclear reactor to obtain each theoretical deposition single spectrum; The correction superposition module is used to correct and superpose all theoretical deposition energy single spectra to obtain the theoretical deposition composite spectrum; as well as, The activity value calculation module is used to calculate the theoretical deposition spectrum through a preset algorithm to obtain the activity value of the nuclide to realize the online monitoring of the fission product nuclides in the core fuel assembly of the nuclear power plant.

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