A method and system for online monitoring of fissile nuclides in a nuclear power plant core fuel assembly

Abstract

The application discloses a kind of nuclear power plant reactor core fuel assembly fission product nuclide online monitoring method and system, the method includes the following steps: based on the measured monospectrum of nuclear power plant reactor core fuel assembly fission product nuclide, energy calibration is carried out, and each theoretical deposition monospectrum is obtained;All theoretical deposition energy monospectrum is corrected and superimposed to obtain theoretical deposition combined spectrum;The activity value of nuclide is obtained by calculating theoretical deposition combined spectrum by preset algorithm, and the online monitoring of nuclear power plant reactor core fuel assembly fission product nuclide is realized.The spectrum drift in the measured monospectrum is corrected in real time, and the activity detection of the nuclide, especially the nuclide with low content in low energy section, of nuclear power plant reactor core fuel assembly fission product nuclide is realized.

Description

Technical Field

[0001] This invention relates to the field of nuclear power technology, and in particular to a method and system for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant reactor cores. Background Technology

[0002] During prolonged operation of the fuel assembly cladding within the reactor, early microcracks may appear due to hydrogenation or wear. Fission product nuclides within these cracks can be released into the primary coolant, leading to increased radioactivity levels. If these early small cracks are not detected promptly, they can worsen into large or multiple cracks under secondary hydrogenation, impacting reactor safety and personnel radiation safety. After long-term reactor operation, when early micro-sized damage occurs in the fuel assembly cladding, the released small amounts of fission product nuclides (such as Xe-133, Xe-135, I-131, Kr-85m, etc.) will be significantly affected by the abundant activation products and Compton scattering present in the pipe walls or primary coolant. The characteristic peaks of low-energy nuclides will be superimposed on the background. If the low-energy background of the gamma spectrum is not fully subtracted, it will affect the extraction of superimposed characteristic peak parameters, especially when the content of low-energy nuclides in the measured object is low, thus affecting the activity analysis of low-energy nuclides.

[0003] To increase the efficiency of energy spectrum analysis of low-concentration, low-energy target nuclides released in the early stages of fuel failure, the higher the cumulative count value for acquiring gamma spectrum data of low-concentration nuclides, the better the statistical results. Therefore, at a certain count rate, a longer measurement time often results in better statistical results. 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 constantly changing. This causes the characteristic peak position of the target nuclide or the entire spectral line to drift continuously during the measurement process. Ultimately, this leads to spectral line broadening over a long period of measurement, a decrease in the energy resolution of the gamma spectrum, and the characteristic peaks of low-energy target nuclides in the superimposed spectrum may still be weak, resulting in inaccurate energy spectrum analysis and inaccurate online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address at least one defect of the related technologies mentioned in the background: the peak shape of the characteristic peaks of the fission products of nuclear power plant core fuel assemblies drifts during the measurement process, resulting in a decrease in the energy resolution of the γ-ray spectrum, and the characteristic peaks of low-energy nuclides in the superimposed spectrum are weak, resulting in inaccurate energy spectrum analysis, thereby leading to inaccurate online monitoring of the nuclides of fission products of nuclear power plant core fuel assemblies. The present invention provides a method and system for online monitoring of the nuclides of fission products of nuclear power plant core fuel assemblies.

[0005] The technical solution adopted by this invention to solve its technical problem is: to construct an online monitoring method for nuclides in the fission products of fuel assemblies in nuclear power plant reactor cores, the method comprising the following steps:

[0006] Based on the measured single spectra of nuclides from the fission products of fuel assemblies in nuclear power plant cores, energy calibration was performed to obtain the single spectra of each theoretical deposition.

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

[0008] The activity values ​​of nuclides are obtained by calculating the theoretical deposition spectrum using a preset algorithm, enabling online monitoring of nuclides in the fission products of nuclear power plant reactor core fuel assemblies.

[0009] In some embodiments, the theoretical deposition single spectrum is obtained by energy calibration based on the measured single spectrum of the fission product nuclides of the nuclear power plant core fuel assembly, including:

[0010] Based on the measured single spectra of nuclides from the fission products of fuel assemblies in nuclear power plant cores, 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 scale parameters is as follows: in, Let i be the energy scaling parameter of the i-th theoretical deposition single spectrum. Let be the channel address of the i-th measured single spectrum, i be the i-th theoretically deposited single spectrum, and a, b, and c be conversion factors.

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

[0013] Based on the counting compensation factor corresponding to each measured single spectrum, each theoretical depositional single spectrum corresponding to the measured single spectrum is corrected to obtain each corrected theoretical depositional single spectrum.

[0014] The theoretical sedimentary composite spectrum is obtained by linearly superimposing all the corrected theoretical sedimentary single spectra.

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

[0016] The formula for calculating the count compensation factor corresponding to each measured single spectrum is as follows: Among them, W i N is the counting compensation factor corresponding to the i-th theoretical sedimentary single spectrum, where i is the i-th theoretical sedimentary single spectrum, and N is the number of spectra. all The total value is the sum of the values ​​across the entire spectrum, and t is the total measurement time. 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 total measurement time corresponding to each measured single spectrum; and / or

[0018] The total measurement time for each measured single spectrum was calculated using the background count rate and the count rate of each nuclide.

[0019] In some embodiments, the number of all corrected theoretical depositional spectra is the number of all theoretical depositional spectra, which is calculated from the total measurement time of the measured spectra.

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

[0021] The count values ​​of each energy point in all the corrected theoretical sedimentary single spectra are linearly superimposed to obtain the theoretical sedimentary 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] Linearly superimpose the count values ​​of the same energy points in all theoretical deposition single spectra after correction;

[0024] The count values ​​corresponding to different energy points in all the corrected theoretical deposition single spectra are obtained by using a preset algorithm, and then linearly superimposed to obtain the theoretical deposition combined spectrum.

[0025] In some embodiments, the activity value of a nuclide is calculated from the theoretical deposition spectrum using a preset algorithm, enabling online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores, including:

[0026] The standard peak shape that is closest to the theoretical deposition spectrum peak shape is selected to fit the peak shape of the theoretical deposition spectrum. The activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape, so as to realize the online monitoring of nuclides of fission products of fuel assembly in nuclear power plant core.

[0027] This invention also constructs an online monitoring system for nuclides in the fission products of fuel assemblies in nuclear power plant cores, comprising:

[0028] The energy calibration module is used to perform energy calibration based on the measured single spectra of each nuclide in the nuclear reactor, and to obtain the theoretical deposition single spectra.

[0029] The correction and overlay module is used to correct and overlay all theoretical depositional energy single spectra to obtain a combined theoretical depositional spectrum; and,

[0030] The activity value calculation module is used to calculate the activity value of nuclides from theoretical deposition spectra using a preset algorithm, enabling online monitoring of nuclides from the fission products of fuel assemblies in nuclear power plant cores.

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

[0032] This invention uses measured single spectra of fission product nuclides from nuclear power plant reactor core fuel assemblies as energy calibration to obtain theoretical deposition single spectra. It corrects spectral drift in the measured single spectra in real time, then corrects and superimposes all theoretical deposition single spectra to obtain a theoretical deposition composite spectrum. Finally, it calculates the activity value of the nuclide from the theoretical deposition composite spectrum using a preset algorithm, thus realizing online monitoring of fission product nuclides from nuclear power plant reactor core fuel assemblies, especially online monitoring of fission product nuclides with low content in the low energy range. Attached Figure Description

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

[0034] Figure 1 A flowchart of one embodiment of the online monitoring method for fission product nuclides of nuclear power plant reactor core fuel assemblies according to the present invention is shown;

[0035] Figure 2 This invention illustrates a single spectrum of measured address-count values ​​before energy calibration in an online monitoring method for fission product nuclides of nuclear power plant reactor core fuel assemblies, as per an embodiment of the present invention.

[0036] Figure 3 This invention illustrates an embodiment of the online monitoring method for nuclides in the fission products of nuclear power plant reactor core fuel assemblies, showing a theoretical deposition monospectral of energy calibration parameters-count values ​​after energy calibration.

[0037] Figure 4 This invention illustrates the standard peak shape of an energy point at E=6134keV in an embodiment of the online monitoring method for fission product nuclides of nuclear power plant reactor core fuel assemblies according to the present invention.

[0038] Figure 5 This invention illustrates the standard peak shape of an energy point at E=1174keV in an embodiment of the online monitoring method for fission product nuclides of nuclear power plant reactor core fuel assemblies according to the present invention.

[0039] Figure 6 The standard peak shape of the energy point at E=511keV is shown in one embodiment of the online monitoring method for fission product nuclides of nuclear power plant reactor core fuel assemblies according to the present invention. Detailed Implementation

[0040] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

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

[0043] Typically, long-term energy spectra are corrected superpositions of multiple short-term measured single spectra. However, in actual measurements, different measured single spectra exhibit spectral drift, causing energy shifts at their corresponding channel addresses. Energy calibration correction of the short-term gamma spectrum is necessary based on changes in the reference peak position. To address the spectral drift problem during long-term sampling of low-concentration, low-energy target nuclides released in the early stages of fuel assembly cladding failure, spectral stabilization is primarily achieved by adjusting spectrometer system parameters, such as high-voltage power supplies and amplifier amplification. However, since the energy spectrum generated by the detection device is susceptible to interference from factors like temperature and high pressure, the primary coolant energy spectrum often drifts. Conventional gain stabilization or reference peak stabilization methods can only adjust the gain deviation of the energy calibration curve. Alternatively, real-time peak finding and peak shape fitting can be performed based on the characteristic peaks of radionuclides in the gamma spectrum, dynamically changing the boundary function by adjusting calibration parameters, thereby achieving spectral stabilization. The advantages of this method are low cost, short processing time, high efficiency, and no need for other hardware facilities. However, it requires fitting the peak shapes of at least two undisturbed characteristic peaks, making it susceptible to the influence of overlapping peaks. Furthermore, the problem of submerging low-energy target nuclides in superimposed spectra is common. Mathematical functions (such as polynomials and exponential functions) are often used to fit the background spectrum, but choosing a suitable fitting function is difficult, especially when dealing with complex spectral lines such as low-energy, low-concentration target nuclide spectra. Poor fitting can introduce errors. Moreover, it may be inaccurate in low-count regions, affecting the results.

[0044] like Figure 1 As shown, some embodiments of the present invention disclose an online monitoring method for nuclides in the fission products of fuel assemblies in nuclear power plant cores. The method includes the following steps:

[0045] Based on the measured single spectra of nuclides from the fission products of fuel assemblies in nuclear power plant cores, energy calibration was performed to obtain the single spectra of each theoretical deposition.

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

[0047] The activity values ​​of nuclides are obtained by calculating the theoretical deposition spectrum using a preset algorithm, enabling online monitoring of nuclides in the fission products of nuclear power plant reactor core fuel assemblies.

[0048] This invention uses measured single spectra of nuclear power plant reactor core fuel assembly fission product nuclides as energy calibration, corrects spectral drift in measured single spectra in real time, and accurately calculates the activity of low-energy, low-content nuclides by calculating theoretically deposited combined spectra.

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

[0050] Based on the measured single spectra of nuclides from the fission products of fuel assemblies in nuclear power plant cores, 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 scale parameters is as follows: +c, where Let i be the energy scaling parameter of the i-th theoretical deposition single spectrum. Let be the channel address of the i-th measured single spectrum, i be the i-th theoretically deposited single spectrum, and a, b, and c be conversion factors.

[0052] For the characteristic peaks of nuclides inherent in the primary coolant of nuclear reactors, such as Na-24, Co-60, Co-58, Ag-110m, Zr-95, Nb-95, and Sb-124, automatic energy calibration references are used for each measured single spectrum, and energy calibration is performed on each measured single spectrum. Specifically, using a gamma-ray standard source with a single energy calibration parameter, such as Cs-137 (661.7 keV), Co-60 (1173.2 keV and 1332.5 keV), the channel addresses of at least three energy calibration parameters are obtained. A nonlinear relationship between the energy calibration parameters and the channel address is established, and the conversion factors a, b, and c are determined through polynomial fitting, for example, a = 3.089 × 10⁻⁶. -8 b = 3.081 × 10 -1 c = 2.159 × 10 -1 Among them, Cs-137 (661.7 keV), Co-60 (1173.2 keV and 1332.5 keV) and a = 3.089 × 10⁻⁶ -8 b = 3.081 × 10 -1 c = 2.159 × 10 -1 This is merely an example and is not intended to limit this application; other examples are also possible.

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

[0054] Based on the counting compensation factor corresponding to each measured single spectrum, each theoretical depositional single spectrum corresponding to the measured single spectrum is corrected to obtain each corrected theoretical depositional single spectrum.

[0055] The theoretical sedimentary composite spectrum is obtained by linearly superimposing all the corrected theoretical sedimentary single spectra.

[0056] The calculation formula for correcting and superimposing all theoretical sedimentary single spectra is as follows: Among them, E p For theoretical sedimentary spectral analysis, Let W be the energy calibration parameter for the i-th theoretical deposition single spectrum. i is the counting compensation factor corresponding to the i-th theoretical sedimentary single spectrum, where i is the i-th theoretical sedimentary single spectrum.

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

[0058] The formula for calculating the count compensation factor corresponding to each measured single spectrum is as follows: Among them, W i N is the counting compensation factor corresponding to the i-th theoretical sedimentary single spectrum, where i is the i-th theoretical sedimentary single spectrum, and N is the number of spectra. all The total value is the sum of the values ​​across the entire spectrum, and t is the total measurement time. dead To measure dead time.

[0059] Due to the existence of dead time, the detector system will ultimately record less signal than the actual event count, resulting in undercounting. This phenomenon is unavoidable; the only solution is to apply dead time correction to the actual detected total spectrum value and calculate the count compensation factor W for each theoretical depositional spectrum. i Among them, N all The total value for the entire spectrum is the sum of the counts for all channel addresses; t dead To measure dead time, which is the time required for the detector to recover to the point where it can process the next pulse signal after processing one pulse signal, the detector cannot receive new signals during this period, which will cause the count value to 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 total measurement time corresponding to each measured single spectrum; and / or

[0061] The total measurement time for each measured single spectrum was calculated using the background count rate and the count rate of each nuclide.

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

[0063] For low-activity nuclides, it is necessary to ensure that the nuclide count rate is significantly higher than the background count rate, i.e., the total measurement time of each measured single spectrum. A total measurement time for each measured single spectrum that satisfies the statistical properties of the nuclide's characteristic peaks is determined. The formula for calculating the total measurement time for each measured single spectrum is as follows: Among them, R Background R is the background count rate. Signal The count rate for each nuclide is 3.29, which is an empirical value. 3.29 is merely an example and is not intended to limit this application. Other values ​​may also be used.

[0064] In some embodiments, the number of all corrected theoretical depositional spectra is the number of all theoretical depositional spectra, which is calculated from the total measurement time of the measured spectra.

[0065] The formula for calculating the number of all theoretically deposited single spectra is: Where n is the number of all corrected theoretical depositional spectra, rounded up if n is not an integer, MDA Pre ε is the expected 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, and 2.71 and 4.66 are empirical values. 2.71 and 4.66 are merely examples here and are not intended to limit this application. Other values ​​may also be used.

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

[0067] The count values ​​of each energy point in all the corrected theoretical sedimentary single spectra are linearly superimposed to obtain the theoretical sedimentary 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] Linearly superimpose the count values ​​of the same energy points in all theoretical deposition single spectra after correction;

[0070] The count values ​​corresponding to different energy points in all the corrected theoretical deposition single spectra are obtained by using a preset algorithm, and then linearly superimposed to obtain the theoretical deposition combined spectrum.

[0071] Specifically, based on the consistency of energy points, the count values ​​of energy points with the same energy at different locations in all corrected theoretical sedimentary single spectra are linearly superimposed; for energy points with different energies in all corrected theoretical sedimentary single spectra, the corresponding count values ​​of each energy point are obtained by interpolation and linearly superimposed to obtain the combined theoretical sedimentary spectra.

[0072] like Figures 4 to 6 As shown, in some embodiments, the activity value of the nuclide is calculated by a preset algorithm based on the theoretical deposition spectrum, thereby enabling online monitoring of nuclides in the fission products of nuclear power plant reactor core fuel assemblies, including:

[0073] The standard peak shape that is closest to the theoretical deposition spectrum peak shape is selected to fit the peak shape of the theoretical deposition spectrum. The activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape, so as to realize the online monitoring of nuclides of fission products of fuel assembly in nuclear power plant core.

[0074] Based on a preset nuclide library, a method for calculating the net peak area of ​​weak peaks under high interference conditions is used. This method involves automatically selecting the closest standard peak shape from the preset nuclide library to fit the theoretical deposition spectrum, which can remove noise from activation and corrosion products to calculate the net peak area and accurately calculate the activity value of nuclides.

[0075] For example, this embodiment provides a method for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores. This method is merely an example and is not intended to limit the scope of this application; other methods may also be used. The specific steps are as follows:

[0076] When this method was applied to the detection of fuel assembly cladding damage in nuclear power plants, during the measurement of fission product nuclides in the primary coolant, the count rate of the target nuclide Xe-133 was found to be 60 cps. The total measured time t for the single spectrum was calculated to be 10 minutes. To detect early signs of abnormal early damage to the fuel assembly cladding, and based on engineering requirements, the expected lower limit of characteristic nuclide detection (MDA) for Xe-133 nuclides was set. Pre 10 7 Bq / m 3 Substituting the expected value of the lower limit of characteristic nuclide detection based on this nuclide... The number of theoretically deposited single spectra was calculated to be 16. Then, the characteristic peaks of Co-58, Ag-110m, and Zr-95 nuclides were used as references for the automatic energy calibration of each measured single spectrum, and the influence of peak drift was corrected in real time. The channel addresses of all measured single spectra are converted into energy calibration parameters, that is, the measured single spectra are inverted into theoretical deposition single spectra of the rays in the detector. Then, considering the measurement dead time effect of each theoretical deposition single spectrum, the following is adopted. Calculate the counting compensation factor W corresponding to the i-th theoretical deposition single spectrum. i and according to The individual theoretical sedimentary spectra were superimposed after dead-time compensation corrections to form a combined theoretical sedimentary spectrum. Finally, using a pre-defined nuclide library-guided method to calculate the net peak area of ​​weak peaks under high interference conditions, the background count rate of Xe-133 was calculated to be 1.6 cps, and the net count rate was 130 cps. The activity concentration of Xe-133 was accurately calculated to be 2.5 × 10⁻⁶. 7 Bq / m 3 This exceeds the early failure limit for fuel assembly cladding.

[0077] This invention employs a time-division stabilization method with automatic energy calibration using energy scale, an adaptive linear superposition method based on dead-time counting compensation factors, and a method for calculating the net peak area of ​​weak peaks under high interference conditions guided by a preset nuclide library. This enables online monitoring of fission product nuclides in nuclear power plant reactor core fuel assemblies. In particular, by correcting the impact of spectral drift on the theoretical deposition single-spectrum acquisition of long-term weak peaks, it accurately calculates the background of low-energy weak peaks, improves the online monitoring of weak fission product nuclides in the primary coolant, increases the efficiency of theoretical deposition single-spectrum analysis of low-concentration, low-energy nuclides released from fuel failure, and detects early damage to fuel assembly cladding earlier.

[0078] Some embodiments of the present invention disclose an online monitoring system for nuclides in the fission products of fuel assemblies in nuclear power plant cores, comprising:

[0079] The energy calibration module is used to perform energy calibration based on the measured single spectra of each nuclide in the nuclear reactor, and to obtain the theoretical deposition single spectra.

[0080] The correction and overlay module is used to correct and overlay all theoretical depositional energy single spectra to obtain a combined theoretical depositional spectrum; and,

[0081] The activity value calculation module is used to calculate the activity value of nuclides from theoretical deposition spectra using a preset algorithm, enabling online monitoring of nuclides from the fission products of fuel assemblies in nuclear power plant cores.

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

[0083] Based on the measured single spectra of nuclides from the fission products of fuel assemblies in nuclear power plant cores, 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 scale parameters is as follows: in, Let i be the energy scaling parameter of the i-th theoretical deposition single spectrum. Let be the channel address of the i-th measured single spectrum, i be the i-th theoretically deposited single spectrum, and a, b, and c be conversion factors.

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

[0086] The correction unit is used to correct each theoretical depositional single spectrum corresponding to each measured single spectrum according to the counting compensation factor corresponding to each measured single spectrum, so as to obtain each corrected theoretical depositional single spectrum.

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

[0088] The calculation formula for correcting and superimposing all theoretical sedimentary single spectra is as follows: Among them, E p For theoretical sedimentary spectral analysis, Let W be the energy calibration parameter for the i-th theoretical deposition single spectrum. i is the counting compensation factor corresponding to the i-th theoretical sedimentary single spectrum, where i is the i-th theoretical sedimentary single spectrum.

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

[0090] The formula for calculating the count compensation factor corresponding to each measured single spectrum is as follows: Among them, W i N is the counting compensation factor corresponding to the i-th theoretical sedimentary single spectrum, where i is the i-th theoretical sedimentary single spectrum, and N is the number of spectra. all The total value is the sum of the values ​​across the entire spectrum, and t is the total measurement time. 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 total measurement time corresponding to each measured single spectrum; and / or

[0092] The total measurement time for each measured single spectrum was calculated using the background count rate and the count rate of each nuclide.

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

[0094] For low-activity nuclides, it is necessary to ensure that the nuclide count rate is significantly higher than the background count rate, i.e., the total measurement time of each measured single spectrum. A total measurement time for each measured single spectrum that satisfies the statistical properties of the nuclide's characteristic peaks is determined. The formula for calculating the total measurement time for each measured single spectrum is as follows: Among them, R Background R is the background count rate. Signal The count rate for each nuclide is 3.29, which is an empirical value. 3.29 is merely an example and is not intended to limit this application. Other values ​​may also be used.

[0095] In some embodiments, the number of all corrected theoretical depositional spectra is the number of all theoretical depositional spectra, which is calculated from the total measurement time of the measured spectra.

[0096] The formula for calculating the number of all theoretically deposited single spectra is: Where n is the number of all corrected theoretical depositional spectra, rounded up if n is not an integer, MDA Pre ε is the expected 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, and 2.71 and 4.66 are empirical values. 2.71 and 4.66 are merely examples here and are not intended to limit this application. Other values ​​may also be used.

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

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

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

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

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

[0102] In some embodiments, the activity value of a nuclide is calculated from the theoretical deposition spectrum using a preset algorithm, enabling online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores, including:

[0103] The standard peak shape that is closest to the theoretical deposition spectrum peak shape is selected to fit the peak shape of the theoretical deposition spectrum. The activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape, so as to realize the online monitoring of nuclides of fission products of fuel assembly in nuclear power plant core.

[0104] It is understood that the above embodiments only illustrate some implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above embodiments or technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. That is, the embodiments described "in some embodiments" can be freely combined with any of the preceding and following embodiments. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.

Claims

1. A method for online monitoring of nuclides in the fission products of fuel assemblies in a nuclear power plant core, characterized in that, The method includes the following steps: Based on the measured single spectra of fission product nuclides from nuclear power plant core fuel assemblies, energy calibration is performed to obtain various theoretical deposition single spectra. This includes: converting the channel addresses of each measured single spectra into energy calibration parameters to obtain various theoretical deposition single spectra; the formula for converting the channel addresses of each measured single spectra into energy calibration parameters is as follows: ,in, Let i be the energy scaling parameter of the i-th theoretical deposition single spectrum. Let be the channel address of the i-th measured single spectrum, i be the i-th theoretical sedimentary single spectrum, and a, b, and c be conversion factors; All theoretical depositional energy single spectra are corrected and superimposed to obtain a theoretical depositional composite spectrum, which includes: correcting each theoretical depositional single spectrum corresponding to each measured single spectrum according to the counting compensation factor corresponding to each measured single spectrum to obtain each corrected theoretical depositional single spectrum; and linearly superimposing all corrected theoretical depositional single spectra to obtain a theoretical depositional composite spectrum. The activity values ​​of nuclides are obtained by calculating the theoretical deposition spectrum using a preset algorithm, enabling online monitoring of nuclides in the fission products of nuclear power plant reactor core fuel assemblies.

2. The method for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores according to claim 1, characterized in that, The count compensation factor corresponding to each measured single spectrum is obtained by correcting the dead time of each measured single spectrum. The formula for calculating the count compensation factor corresponding to each measured single spectrum is as follows: ,in, Let be the counting compensation factor corresponding to the i-th theoretical sedimentary single spectrum, where i is the i-th theoretical sedimentary single spectrum. The total value is the sum of the values ​​across the entire spectrum, and t is the total measurement time. To measure dead time.

3. The method for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores according to claim 2, characterized in that, The measurement dead time for each measured single spectrum is obtained by subtracting the measurement live time for each measured single spectrum from the total measurement time for each measured single spectrum; and / or The total measurement time for each measured single spectrum was calculated using the background count rate and the count rate of each nuclide.

4. The method for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores according to claim 1, characterized in that, The total number of all corrected theoretical sedimentary spectra is the total number of all theoretical sedimentary spectra, which is calculated from the total measurement time of the measured spectra.

5. The method for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores according to claim 1, characterized in that, Linear superposition of all corrected theoretical sedimentary single spectra yields the theoretical sedimentary composite spectra, including: The count values ​​of each energy point in all the corrected theoretical sedimentary single spectra are linearly superimposed to obtain the theoretical sedimentary composite spectrum.

6. The method for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores according to claim 5, characterized in that, The count values ​​of each energy point in all the corrected theoretical sedimentary single spectra are linearly superimposed to obtain the theoretical sedimentary composite spectrum, including: Linearly superimpose the count values ​​of the same energy points in all theoretical deposition single spectra after correction; The count values ​​corresponding to different energy points in all the corrected theoretical deposition single spectra are obtained by using a preset algorithm, and then linearly superimposed to obtain the theoretical deposition combined spectrum.

7. The method for online monitoring of nuclides in the fission products of fuel assemblies in nuclear power plant cores according to claim 1, characterized in that, The activity values ​​of nuclides are calculated from the theoretical deposition spectrum using a preset algorithm, enabling online monitoring of nuclides in the fission products of nuclear power plant reactor core fuel assemblies, including: The standard peak shape that is closest to the theoretical deposition spectrum peak shape is selected to fit the peak shape of the theoretical deposition spectrum. The activity value of the nuclide is calculated from the fitted theoretical deposition spectrum peak shape, so as to realize the online monitoring of nuclides of fission products of fuel assembly in nuclear power plant core.

8. An online monitoring system for nuclides in the fission products of fuel assemblies in a nuclear power plant core, characterized in that, include: The energy calibration module is used to perform energy calibration based on the measured single spectra of various nuclides in a nuclear reactor, obtaining the theoretical deposition single spectra. This includes: converting the channel addresses of each measured single spectra into energy calibration parameters based on the measured single spectra of fission product nuclides from the fuel assemblies in the nuclear power plant core, thus obtaining the theoretical deposition single spectra; the formula for converting the channel addresses of each measured single spectra into energy calibration parameters is as follows: ,in, Let i be the energy scaling parameter of the i-th theoretical deposition single spectrum. Let be the channel address of the i-th measured single spectrum, i be the i-th theoretical sedimentary single spectrum, and a, b, and c be conversion factors; The correction and overlay module is used to correct and overlay all theoretical depositional energy single spectra to obtain a theoretical depositional composite spectrum. It includes: correcting each theoretical depositional single spectrum corresponding to the measured single spectrum according to the count compensation factor corresponding to each measured single spectrum, obtaining corrected theoretical depositional single spectra; linearly overlaying all corrected theoretical depositional single spectra to obtain the theoretical depositional composite spectrum; and... The activity value calculation module is used to calculate the activity value of nuclides from theoretical deposition spectra using a preset algorithm, enabling online monitoring of nuclides from the fission products of fuel assemblies in nuclear power plant cores.

Images