In-core circulation tracing method for high temperature gas cooled reactor spherical element

Abstract

This invention relates to an in-core circulation tracing method for spherical elements in a high-temperature gas-cooled reactor. The method includes: identifying and encoding the spherical elements by adding a marker target; the marker target includes a target core element... 59 Co、 191 Ir、 169 Tm contains one, two, or three combinations, and contains at least one of them. 59 Co, different identification targets include different types and / or proportions of target core elements, and the spherical elements include fuel elements and / or graphite spheres. An embodiment of the present invention provides an in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor, enabling online and non-destructive acquisition of spherical element circulation tracing data. The method of this embodiment can accurately identify the identification code of the spherical elements using a high-purity germanium gamma spectrometer within the existing burnup measurement system of the high-temperature gas-cooled reactor, without requiring an additional measurement system, thus saving costs.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear reactor in-core circulation test, in particular, the present application relates to a kind of high temperature gas cooled reactor spherical element in-core circulation tracing method. BACKGROUND

[0002] High temperature gas cooled reactor is a kind of fourth generation advanced nuclear reactor with inherent safety characteristics, high thermal energy conversion efficiency, which uses graphite as moderator, helium as coolant and adopts ceramic core structure.

[0003] The reactor core of high temperature gas cooled reactor nuclear power station in initial installation and transition circulation operation stage is two kinds of spherical elements of fuel element and graphite ball, and the reactor core in equilibrium circulation operation stage after the end of transition circulation operation stage is one kind of spherical element of fuel element.

[0004] High temperature gas cooled reactor adopts spherical fuel element, which is composed of inner spherical fuel area and outer shell fuel-free area, and fuel particles are dispersed in the graphite matrix of spherical fuel area, and the outer shell fuel-free area is made of the same material as the graphite matrix of spherical fuel area, without fuel particles. Through the in-core fuel circulation operation mode of multiple loading and unloading of high temperature gas cooled reactor core, a certain degree of uniformity of reactor power and burnup distribution is obtained.

[0005] However, the spherical flow movement of spherical fuel element in high temperature gas cooled reactor has randomness, and the flow line and flow velocity distribution of spherical flow are relatively complex. If the actual fuel circulation number of spherical fuel element deviates from the design value of high temperature gas cooled reactor fuel or the residence time in reactor core is too long, it will affect the safe operation of high temperature gas cooled reactor and the service life of ceramic core structure, so obtaining fuel circulation tracing data of spherical fuel element is a problem that must be solved for spherical flow modeling and fuel partition modeling of high temperature gas cooled reactor.

[0006] It is a direct method to obtain fuel circulation tracing data of spherical fuel element through identification coding and multiple core loading and unloading by fuel loading and unloading system. The conventional identification coding method is to use mechanical method to draw identification coding on the surface of spherical fuel element, and then to visually identify. However, the identification coding drawn on the surface of spherical fuel element by mechanical method is damaged due to friction, collision and fluid scouring during the spherical flow process, and it is also impossible to detect when the identified coded spherical fuel element is unloaded from the core in the fuel circulation process. Visual identification of identification coding needs to be carried out in a lead room with radioactive shielding, so the conventional identification coding method and visual identification method are not suitable for fuel circulation tracing of spherical fuel element of high temperature gas cooled reactor. SUMMARY

[0007] The present application aims to at least solve one of the technical problems in the related art. To this end, embodiments of the present application propose a high-temperature gas-cooled reactor spherical element in-core circulation tracing method.

[0008] Embodiments of the present application propose a high-temperature gas-cooled reactor spherical element in-core circulation tracing method, which comprises: adding an identification target in the spherical element to achieve identification coding of the spherical element; the target nuclear element included in the identification target is a combination of one, two or three of 59 Co, 191 Ir, 169 Tm, and at least contains 59 Co, and the types and / or ratios of the target nuclear elements included in different identification targets are different, and the spherical element comprises a fuel element and / or a graphite sphere.

[0009] The high-temperature gas-cooled reactor spherical element in-core circulation tracing method of the embodiments of the present application can obtain spherical element circulation tracing data on-line and non-destructively. The method of the embodiments of the present application can accurately identify the identification coding of the spherical element by using the high-purity germanium gamma spectrometer of the existing burnup measurement system of the high-temperature gas-cooled reactor, without the need to increase an additional measurement system, thereby saving costs.

[0010] The embodiments of the present application select 59 Co, 191 Ir, 169 Tm as the identification target to identify and code the spherical element, and the nuclear reaction formulae thereof are respectively 59 Co(n,γ) 60 Co, 191 Ir(n,γ) 192 Ir and 169 Tm(n,γ) 170 Tm, which avoids the radioactive nuclides contained in the fission products of the fuel element, and the gamma ray energy peaks and emission intensities of the radioactive nuclides 60 Co, 192 Ir, 170 Tm have sufficient distinguishability. Specifically, 60 The two main gamma ray energy peaks of 192 The gamma ray energy peak of 170 The gamma ray energy peak of 60 Co, 192 Ir and 170 Tm have sufficient distinguishability, thereby ensuring the accuracy of the measurement results.

[0011] In some embodiments, the amount of target core element used in the identification target is: 59 Co is 1 to N parts. 191 Ir is 0-2 parts. 169 Tm is 0 to 3 parts, and N is an integer between 2 and 41.

[0012] This invention, through combining the types and contents of target elements in the identification target, utilizes the different characteristic γ-energy peaks and relative intensities of the corresponding radionuclides produced by the (n,γ) reaction of the target elements in the reactor to achieve the identification and encoding of spherical elements. The types and / or proportions of target elements in the identification target are designed according to the number of spherical elements required for identification and encoding in in-reactor cyclic tracing.

[0013] In some embodiments, in each of the spherical elements, 59 The content of Co is 0.1mg to N / 10mg. 191 The content of Ir is 0mg to 0.2mg. 169 The content of Tm is 0mg to 0.3mg, and N is an integer between 2 and 41.

[0014] In this embodiment of the invention, by controlling the components in each spherical element 59 Co、 191 Ir、 169 The Tm content is within the above range, thereby ensuring that the radioactivity of the target core element generated by the (n,γ) reaction in the reactor is within the range of 7.0 × 10⁻⁶ for the standard calibration source and verification source of the high-temperature gas-cooled reactor burnup measurement system. 5 ~1.0×10 10 Bq phase compatibility ensures that the marking target does not significantly affect the mechanical integrity of the spherical element or the radiation protection of the operation of the high-temperature gas-cooled reactor burnup measurement system.

[0015] In some embodiments, the identification target 59 The raw material for Co is selected from either elemental cobalt or electroplated cobalt. 191 The raw material for Ir is selected from one of elemental iridium or iridium-10% gold alloy. 169 The raw materials for Tm are selected from either elemental thulium or Tm2O3.

[0016] At rated power, the highest temperature at the center of the fuel element (balanced core) in a high-temperature gas-cooled reactor reaches 900°C. The melting points of cobalt, iridium, and thulium are 1495°C, 2443°C, and 1545°C, respectively. Therefore, the marked target... 59 The raw material for Co can be selected from elemental cobalt or electroplated cobalt. 191The raw material of Ir can be selected from one of iridium single substance, iridium-10% gold alloy, and the like. 169 The raw material of Tm can be selected from one of thulium single substance, Tm2O3, and the like.

[0017] In some embodiments, the identification target is in the form of granules, filaments, flakes, metal plating, glass body with carrier substance, or graphite powder tablet. Preferably, the identification target is in the form of granules.

[0018] In some embodiments, the fuel elements are divided into several groups, each group loaded with different enrichment degree of 235 U.

[0019] In some embodiments, the fuel element comprises an inner layer of spherical fuel region and an outer layer of non-fuel region, and the identification target is added to the outer layer of non-fuel region of the fuel element.

[0020] In some embodiments, the diameter of the inner layer of spherical fuel region is 50 mm, and the thickness of the outer layer of non-fuel region is 2.5-7.5 mm, preferably 5 mm.

[0021] In some embodiments, the inner layer of spherical fuel region comprises a graphite matrix and coated fuel particles, the coated fuel particles are dispersed in the graphite matrix, and the coated fuel particles contain uranium; the outer layer of non-fuel region comprises a graphite matrix and an identification target, the identification target is added to the graphite matrix of the outer layer of non-fuel region, and the material of the graphite matrix of the inner layer of spherical fuel region is the same as that of the outer layer of non-fuel region.

[0022] In some embodiments, the identification target is coated with a coating material and added to the graphite matrix of the outer layer of non-fuel region of the fuel element in the form of granules, and the coating material is the same as the graphite matrix of the outer layer of non-fuel region.

[0023] In some embodiments, the identification target is coated with a coating material and pressed into the outer layer of non-fuel region of the fuel element by quasi-isostatic pressing process.

[0024] In some embodiments, the identification target is coated with a coating material and added to the graphite sphere, and the coating material is the same as the material of the graphite sphere.

[0025] In some embodiments, the raw material of the graphite matrix powder is 64% natural flake graphite, 16% artificial graphite, and 20% phenolic resin in mass fraction, and is prepared by a process comprising mixing, extruding, crushing, and sieving.

[0026] In some embodiments, the method further comprises: identifying the identification code of the spherical element by measuring the combination of the corresponding gamma-ray emission intensities characterized by the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV in the spherical element discharged from the high-temperature gas-cooled reactor pebble bed core.

[0027] In some embodiments, the measuring is performed by a high-purity germanium gamma spectrometer of the burnup measurement system.

[0028] In some embodiments, the method of identifying comprises:

[0029] acquiring the kind, amount and activity of each radionuclide of the identification target in the spherical element;

[0030] calculating the preset value of the combination of the corresponding gamma-ray emission intensities characterized by the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV of the corresponding spherical element;

[0031] comparing the combination of the corresponding gamma-ray emission intensities characterized by the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV of the spherical element discharged from the high-temperature gas-cooled reactor pebble bed core with the preset value, and identifying the identification code of the spherical element.

[0032] The present application also provides a spherical element for a high-temperature gas-cooled reactor, wherein the spherical element is provided with an identification target, and the identification target comprises one, two or three of the following target nuclear elements in combination, and at least contains 59 Co, 191 Ir, 169 Tm, and the amount of each target nuclear element is as follows: 59 Co, and different identification targets comprise different kinds and / or ratios of target nuclear elements, and the spherical element is a fuel element or a graphite sphere.

[0033] In some embodiments, the amount of each target nuclear element in the identification target is as follows: 59 Co is 1-N parts, 191 Ir is 0-2 parts, 169 Tm is 0-3 parts, and N is an integer between 2 and 41.

[0034] In some embodiments, the content of each of the following in each spherical element is as follows: 59 Co is 0.1 mg-N / 10 mg, 191 Ir is 0 mg-0.2 mg, 169 Tm is 0 mg-0.3 mg, and N is an integer between 2 and 41.

[0035] In some embodiments, the identification target is added to the fuel element in the form of a particle, a wire, a sheet, a metal plating layer, a glass body with a carrier substance, or a graphite powder tablet; preferably in the form of a particle. 59 The raw material of Co is selected from one of cobalt single substance, and electroplated cobalt, and the raw material of Co is added to the fuel element in the form of a particle, a wire, a sheet, a metal plating layer, a glass body with a carrier substance, or a graphite powder tablet; preferably in the form of a particle. 191 The raw material of Ir is selected from one of iridium single substance, and iridium-10% gold alloy, and the raw material of Ir is added to the fuel element in the form of a particle, a wire, a sheet, a metal plating layer, a glass body with a carrier substance, or a graphite powder tablet; preferably in the form of a particle. 169 The raw material of Tm is selected from one of thulium single substance, and Tm2O3, and the raw material of Tm is added to the fuel element in the form of a particle, a wire, a sheet, a metal plating layer, a glass body with a carrier substance, or a graphite powder tablet; preferably in the form of a particle.

[0036] In some embodiments, the identification target is added to the fuel element in the form of a particle, a wire, a sheet, a metal plating layer, a glass body with a carrier substance, or a graphite powder tablet; preferably in the form of a particle.

[0037] In some embodiments, the fuel element comprises an inner layer of spherical fuel region and an outer shell of fuel-free region, and the identification target is added to the fuel-free region of the outer shell of the fuel element.

[0038] In some embodiments, the diameter of the inner layer of spherical fuel region is 50 mm, and the thickness of the outer shell of fuel-free region is 2.5-7.5 mm, preferably 5 mm.

[0039] In some embodiments, the inner layer of spherical fuel region comprises a graphite matrix and coated fuel particles, the coated fuel particles are dispersed in the graphite matrix, and the coated fuel particles contain uranium; the outer shell of fuel-free region comprises a graphite matrix and an identification target, the identification target is added to the graphite matrix of the outer shell of fuel-free region, and the material of the graphite matrix of the inner layer of spherical fuel region is the same as that of the outer shell of fuel-free region.

[0040] In some embodiments, the identification target is coated with a coating material and added to the graphite matrix of the outer shell of fuel-free region of the fuel element in the form of a particle, and the coating material is the same as the graphite matrix of the outer shell of fuel-free region.

[0041] In some embodiments, the raw material of the graphite matrix is 64% natural flake graphite, 16% artificial graphite, and 20% phenolic resin in mass fraction, and the graphite matrix is prepared by a process comprising kneading, extruding, crushing, and sieving.

[0042] In some embodiments, the identification target is coated with a coating material and pressed in the outer shell of fuel-free region of the fuel element by quasi-isostatic pressing process.

[0043] In some embodiments, the identification target is coated with a coating material and added to the graphite sphere, and the coating material is the same as the material of the graphite sphere.

[0044] In some embodiments, the raw material of the graphite matrix is 64% natural flake graphite, 16% artificial graphite, and 20% phenolic resin in mass fraction, and the graphite matrix is prepared by a process comprising kneading, extruding, crushing, and sieving.

[0045] The features and advantages described above in relation to the identification target also apply to the spherical element with the identification target, and are not repeated here.

[0046] The embodiment of the present application also provides a high-temperature gas cooled reactor system, comprising the spherical element for the high-temperature gas cooled reactor.

[0047] The features and advantages described above in relation to the identification target also apply to the high-temperature gas cooled reactor system containing the spherical element with the identification target, and are not repeated here.

[0048] The present application has the following advantages and beneficial effects:

[0049] (1) The embodiment of the present application provides a high-temperature gas cooled reactor spherical element in-core circulation tracing method, which can obtain spherical element circulation tracing data on-line and non-destructively. The high-temperature gas cooled reactor spherical flow model and / or fuel partition model are improved, the accuracy of physical thermal calculation analysis is improved, and the safe operation of the high-temperature gas cooled reactor is ensured.

[0050] (2) The embodiment of the present application can accurately identify the identification code of the spherical element by using the high-purity germanium gamma spectrometer of the existing burnup measurement system of the high-temperature gas cooled reactor, without the need to increase an additional measurement system, thereby saving cost.

[0051] (3) The present application is realized by using a mature radiation measurement method, the measurement process is stable, and the measurement result is accurate. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is a high-temperature gas cooled reactor fuel element structure schematic diagram.

[0053] Figure 2 is a high-temperature gas cooled reactor fuel loading and unloading system schematic diagram.

[0054] Figure 3 is a high-temperature gas cooled reactor system containing the spherical element with the identification target according to the embodiment of the present application. 59 Co 25 parts, 191 Ir 2 parts and 169 Tm 3 parts (the mass of each metal is about 0.1 mg) of the identification target radioactive activity curve.

[0055] Reference signs:

[0056] 101 is a fuel element, 102 is a half sphere, 103 is an outer shell fuel-free area, and 104 is an inner layer spherical fuel area.

[0057] 201 is a reactor pressure vessel, 202 is a core discharge device, 203 is a burnup measurement system, 204 is a discharge temporary storage device, and 205 is a new fuel tank. DETAILED DESCRIPTION

[0058] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0059] This invention proposes an in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor. The method includes: adding a marker target to the spherical element to achieve marker encoding; the marker target includes a target core element... 59 Co、 191 Ir、 169 Tm contains one, two, or three combinations, and contains at least one of them. 59 Co, different identification targets include different types and / or proportions of target core elements, and spherical elements include fuel elements and / or graphite spheres.

[0060] This invention provides a method for in-pile circulation tracing of spherical elements in a high-temperature gas-cooled reactor, enabling online and non-destructive acquisition of spherical element circulation tracing data. The method utilizes the high-purity germanium gamma spectrometer within the existing burnup measurement system of the high-temperature gas-cooled reactor to accurately identify the identification code of the spherical elements, eliminating the need for additional measurement systems and saving costs.

[0061] The present invention embodiment selects 59 Co、 191 Ir、 169 One, two, or three of the elements in Tm are used as identification targets to identify and encode spherical elements, and their nuclear reaction formulas are respectively... 59 Co(n,γ) 60 Co、 191 Ir(n,γ) 192 Ir and 169 Tm(n,γ) 170 Tm avoids the radioactive nuclides contained in the fission products of fuel elements, and the radioactive nuclides 60 Co、 192 Ir、 170 The gamma-ray energy peak and emission intensity of Tm are sufficiently distinguishable. Specifically, 60 The two main gamma-ray energy peaks of Co are 1173.228 keV and 1332.492 keV, respectively. 192 The gamma-ray energy peak of Ir is 316.506 keV. 170 The gamma-ray energy peak of Tm is 84.255 keV, forming high-, medium-, and low-energy gamma-ray radionuclides. High-purity germanium gamma-ray spectrometers generally have a resolution better than 1.85 keV; therefore, high-purity germanium gamma-ray spectrometers are better for... 60 Co、 192 Ir and 170 The γ-ray energy peak of Tm has sufficient distinguishability, thus ensuring the accuracy of the measurement results.

[0062] In some embodiments, the amount of the target nuclear element in the identification target is: 59 Co is 1~N parts, 191 Ir is 0~2 parts, 169 Tm is 0~3 parts, and N is an integer between 2~41.

[0063] In the embodiments of the present application, the types and contents of the target nuclear elements in the identification target are combined, and the different characteristic gamma energy peaks and relative intensity combinations of the corresponding radionuclides generated by the (n, γ) reaction of the target nuclear elements in the reactor are used to realize the identification coding of the spherical elements. The types and / or ratios of the target nuclear elements of the identification target are designed according to the number of the identification coded spherical elements required by the in-pile circulation tracing.

[0064] It can be understood that the types and contents of the target nuclear elements in the identification target are combined, that is, 59 Co can be 1, 2, …, N parts (N choices), 191 Ir is 0, 1, 2 parts (3 choices), 169 Tm is 0, 1, 2, 3 parts (4 choices); N is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 or 41; and the types and / or ratios of the target nuclear elements of the identification target are designed according to the number of the identification coded spherical elements required by the in-pile circulation tracing.

[0065] Non-limiting examples are as follows:

[0066] In a specific example, when the number of the identification coded spherical elements required by the in-pile circulation tracing is 300, the following can be used: 59 Co is 1~25 parts, 191 Ir is 0~2 parts, 169 Tm is 0~3 parts, to obtain 300 combinations.

[0067] In a specific example, when the number of the identification coded spherical elements required by the in-pile circulation tracing is 270, the following can be used: 59 Co is 1~30 parts, 191 Ir is 0~2 parts, 169 Tm is 0~2 parts, to obtain 270 combinations.

[0068] In a specific example, when the number of the identification coded spherical elements required by the in-pile circulation tracing is 240, the following can be used: 59 Co is 1~30 parts, 191 Ir is 0~1 part,169 Tm is 0-3 parts, 240 combinations are obtained.

[0069] In a specific example, when the number of identification coded spherical elements required for in-pile circulating tracing is 360, the number of combinations can be calculated as follows: 59 Co is 1-40 parts, 191 Ir is 0-2 parts, 169 Tm is 0-2 parts, 360 combinations are obtained.

[0070] In a specific example, when the number of identification coded spherical elements required for in-pile circulating tracing is 270, the number of combinations can be calculated as follows: 59 Co is 1-35 parts, 191 Ir is 0-2 parts, 169 Tm is 0-3 parts, 420 combinations are obtained.

[0071] 60 Co, 192 Ir and 170 Tm are calculated as follows:

[0072] Cobalt, iridium and thulium as target materials are respectively subjected to neutron irradiation in a reactor to produce 59 Co(n, γ) 60 Co, 191 Ir(n, γ) 192 Ir and 169 Tm(n, γ) 170 Tm nuclear reactions, and the nuclear reaction equations are respectively:

[0073]

[0074]

[0075]

[0076] The theoretical specific activity calculation formula is:

[0077]

[0078]

[0079]

[0080] In the formula:

[0081] A CO : 60 Co specific activity, Bq / g;

[0082] A Ir : 192 Ir specific activity, Bq / g;

[0083] A Tm : 170 Tm specific activity, Bq / g

[0084] N0: target nucleus number of target nucleus element per 1 g (considering the abundance of target nucleus element)

[0085] σ: 59 Co, 191 Ir, 169 thermal neutron capture cross section of Tm, cm 2

[0086] σ': 192 Ir, 170 thermal neutron capture cross section of Tm, cm 2

[0087] λ: 60 Co, 192 Ir, 170 decay constant of Tm

[0088] Φ: thermal neutron fluence rate, cm -2 ·s -1

[0089] t: irradiation time, s

[0090] In order to make the method of the embodiment of the present application measured by the high purity germanium gamma spectrometer of the existing burnup measurement system of the high temperature gas cooled reactor, it is required that the radioactivity of the target nucleus element of the identification target produced by the (n, γ) reaction in the reactor is adapted to the radioactivity range 7.0×10 5 ~1.0×10 10 Bq of the standard calibration source and the check source of the burnup measurement system of the high temperature gas cooled reactor, and at the same time, it is also required that the identification target does not obviously affect the mechanical integrity of the spherical element and the radiation protection of the operation of the burnup measurement system of the high temperature gas cooled reactor. Through the calculation and deduction of the above formula, it is obtained that the matching target nucleus element of 1 part in each spherical element is about 0.1 mg, and the maximum value of the natural number N is 41.

[0091] In some embodiments, the content of the target nucleus element in each spherical element is 59 0.1 mg ~ N / 10 mg, 191 0 mg ~ 0.2 mg of Ir, 169 0 mg ~ 0.3 mg of Tm, and N is an integer between 2 and 41.

[0092] In some embodiments, the raw material of the target nucleus element in the identification target is selected from one of cobalt single substance and electroplated cobalt. 59 191 ​The raw material of Ir is selected from one of iridium single substance, iridium-10% gold alloy, 169 The raw material of Tm is selected from one of thulium single substance, Tm2O3.

[0093] The maximum temperature of the fuel element in the high temperature gas cooled reactor reaches 900℃ under the rated power (equilibrium core), and the melting points of cobalt, iridium and thulium are 1495℃, 2443℃ and 1545℃ respectively, so the 59 The raw material of Co can be selected from one of cobalt single substance, electroplated cobalt, 191 The raw material of Ir can be selected from one of iridium single substance, iridium-10% gold alloy, 169 The raw material of Tm can be selected from one of thulium single substance, Tm2O3.

[0094] In some embodiments, the identification target is in the form of granules, filaments, sheets, electroplated metal layer, glass body with carrier substance or graphite powder pressed sheet. Preferably, the identification target is in the form of granules.

[0095] In some embodiments, the fuel elements are divided into several types, each loaded with different enrichment of 235 U.

[0096] In some embodiments, the fuel element comprises an inner spherical fuel region and an outer shell fuel-free region, and the identification target is added to the outer shell fuel-free region of the fuel element.

[0097] In some embodiments, the diameter of the inner spherical fuel region is 50mm, and the thickness of the outer shell fuel-free region is 2.5-7.5mm, preferably 5mm.

[0098] In some embodiments, the inner spherical fuel region comprises a graphite matrix and coated fuel particles, the coated fuel particles are dispersed in the graphite matrix, and the coated fuel particles contain uranium; the outer shell fuel-free region comprises a graphite matrix and an identification target, the identification target is added to the graphite matrix of the outer shell fuel-free region, and the graphite matrix of the inner spherical fuel region and the outer shell fuel-free region is the same.

[0099] In some embodiments, the identification target is coated with a coating material and added to the graphite matrix of the outer shell fuel-free region of the fuel element in the form of granules, and the coating material is the same as the graphite matrix of the outer shell fuel-free region.

[0100] In some embodiments, the identification target is coated with a coating material and pressed into the outer shell fuel-free region of the fuel element by quasi-isostatic pressing process.

[0101] It can be understood that the manufacturing and testing process of the fuel element with the identification target is the same as that of the conventional fuel element (fuel element without the identification target) except for the addition of the identification target.

[0102] In some embodiments, the identification target is added to the graphite sphere after the graphite sphere is coated with the coating material which is the same base graphite powder as the material of the graphite sphere.

[0103] In some embodiments, the raw material of the base graphite powder is 64% natural flake graphite, 16% artificial graphite and 20% phenolic resin in mass fraction, and is prepared by a process including kneading, extruding, crushing and sieving.

[0104] It can be understood that the manufacturing and detection process of the graphite sphere with the identification target is the same as the manufacturing and detection process of the conventional graphite sphere (the graphite sphere without the identification target) except for the addition of the identification target.

[0105] In some embodiments, the method further comprises: identifying the identification code of the spherical element by measuring the combination of the corresponding gamma-ray emission intensities of the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV in the spherical element discharged from the high temperature gas cooled reactor pebble bed core.

[0106] In some embodiments, the measurement is performed by a high purity germanium gamma spectrometer of the burnup measurement system.

[0107] In some embodiments, the identification method comprises:

[0108] Obtaining the type, amount and activity of each radionuclide of the identification target in the spherical element;

[0109] Calculating the preset value of the combination of the corresponding gamma-ray emission intensities of the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV of the corresponding spherical element;

[0110] Comparing the combination of the corresponding gamma-ray emission intensities of the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV of the spherical element discharged from the high temperature gas cooled reactor pebble bed core with the preset value, and identifying the identification code of the spherical element.

[0111] The tracer method of the spherical element in the high-temperature gas cooled reactor fuel cycle provided by the embodiment of the present application can obtain the cycle data of the fuel element in the reactor core for multiple different periods in a line and non-destructive manner, and the measured data reflecting the randomness of the spherical flow movement and the path of the spherical flow are used to implement iterative calculation on the spherical flow model of the high-temperature gas cooled reactor physical and thermal calculation software to improve and verify the core radial flow channel partition and axial fuel layering model, so that the accuracy of the high-temperature gas cooled reactor physical and thermal calculation analysis can be improved, and the spherical flow modeling problem of the high-temperature gas cooled reactor in the world can be solved to a certain extent, and the safe operation of the high-temperature gas cooled reactor is ensured.

[0112] The embodiment of the present application also provides a spherical element for a high-temperature gas cooled reactor, the spherical element is a fuel element or a graphite ball, and a marking target is added to the spherical element. 59 Co, 191 Ir, 169 Tm in combination of one, two or three, and at least containing 59 Co, the types and / or ratios of the target nuclear elements included in different marking targets are different.

[0113] In some embodiments, the amount of the target nuclear element in the marking target is: 59 Co is 1-N parts, 191 Ir is 0-2 parts, 169 Tm is 0-3 parts, and N is an integer between 2 and 41.

[0114] In some embodiments, in each spherical element, 59 the content of Co is 0.1 mg-N / 10 mg, 191 the content of Ir is 0 mg-0.2 mg, 169 the content of Tm is 0 mg-0.3 mg, and N is an integer between 2 and 41.

[0115] In some embodiments, the raw material of 59 Co is selected from one of cobalt single substance and electroplated cobalt, 191 the raw material of Ir is selected from one of iridium single substance and iridium-10% gold alloy, 169 the raw material of Tm is selected from one of thulium single substance and Tm2O3.

[0116] In some embodiments, the marking target is in a granular, filamentous, flaky, metal electroplated layer, glass body with carrier substance or graphite powder pressed sheet; preferably in a granular form.

[0117] In some embodiments, the fuel element comprises an inner spherical fuel area and an outer shell fuel-free area, and the marking target is added to the outer shell fuel-free area of the fuel element.

[0118] In some embodiments, the inner layer of the spherical fuel region has a diameter of 50 mm, and the cladding fuel-free region has a thickness of 2.5-7.5 mm, preferably 5 mm.

[0119] In some embodiments, the inner layer of the spherical fuel region comprises a graphite matrix and coated fuel particles dispersed in the graphite matrix, and the coated fuel particles contain uranium; the cladding fuel-free region comprises a graphite matrix and the marker target added to the graphite matrix of the cladding fuel-free region, and the material of the inner layer of the spherical fuel region is the same as the graphite matrix of the cladding fuel-free region.

[0120] In some embodiments, the marker target is coated with a coating material in the form of particles and added to the graphite matrix of the cladding fuel-free region of the fuel element, and the coating material is the same as the graphite matrix of the cladding fuel-free region.

[0121] In some embodiments, the raw material of the graphite matrix powder is 64% natural flake graphite, 16% artificial graphite, and 20% phenolic resin by mass fraction, and is prepared by a process comprising kneading, extrusion, crushing, and screening.

[0122] In some embodiments, the marker target is coated with a coating material and pressed into the cladding fuel-free region of the fuel element by quasi-isostatic pressing.

[0123] In some embodiments, the marker target is coated with a coating material in the form of particles and added to the graphite matrix of the cladding fuel-free region of the fuel element, and the coating material is the same as the graphite matrix of the cladding fuel-free region.

[0124] In some embodiments, the raw material of the graphite matrix powder is 64% natural flake graphite, 16% artificial graphite, and 20% phenolic resin by mass fraction, and is prepared by a process comprising kneading, extrusion, crushing, and screening.

[0125] The features and advantages described above for the marker target also apply to the spherical element with the marker target, and are not repeated here.

[0126] The embodiments of the present application also provide a high-temperature gas-cooled reactor system comprising the spherical element with the marker target for the high-temperature gas-cooled reactor described above.

[0127] The features and advantages described above for the marker target also apply to the high-temperature gas-cooled reactor system containing the spherical element with the marker target, and are not repeated here.

[0128] Figure 1 A schematic diagram of a high-temperature gas-cooled reactor fuel element structure. The fuel element 101 comprises an inner layer of the spherical fuel region 104 and a cladding fuel-free region 103, and a marker target (not shown in the figure) for marking is added to the cladding fuel-free region 103 of the fuel element 101.

[0129] Figure 2 Figure 1 is a schematic diagram of an existing high-temperature gas-cooled reactor fuel handling system. The high-temperature gas-cooled reactor fuel handling system comprises a reactor pressure vessel 201, a core discharge device 202, a burnup measurement system 203, a discharge temporary storage device 204, and a fresh fuel tank 205. The bottom outlet of the reactor pressure vessel 201 is connected to the core discharge device 202. The outlet of the core discharge device 202 is connected to the burnup measurement system 203. The burnup measurement system 203 comprises a first outlet and a second outlet. The first outlet is connected to the inlet of the reactor pressure vessel 201 through a main circulating ball loop. The second outlet is connected to the discharge temporary storage device 204 through a spent fuel discharge loop. The outlet of the fresh fuel tank 205 is connected to the inlet of the reactor pressure vessel 201 through the main circulating ball loop.

[0130] Figure 3 Figure 1 shows a radioactive activity curve of a target containing 59 Co 25 parts, 191 Ir 2 parts and 169 Tm 3 parts (the mass of each metal is about 0.1 mg) according to an embodiment of the present application.

[0131] Example 1

[0132] The present embodiment provides a high-temperature gas-cooled reactor fuel element in-core fuel cycle tracing method, comprising:

[0133] S1, selecting a target nuclear element of the target as a combination of 59 Co, 191 Ir, 169 Tm;

[0134] selecting a target nuclear element of the target as 59 Co, 191 Ir, and 169 Tm. 59 Co(n,γ) 60 Co, 191 Ir(n,γ) 192 Ir, and 169 Tm(n,γ) 170 Tm. 60 Co, 192 Ir, and 170 Tm. 60 Co, 192 Ir, and 170 Tm are not radioactive nuclides contained in the fission products of the fuel element, 60 Co have two main γ-ray energy peaks of 1173.228 keV and 1332.492 keV, respectively, 192The gamma-ray energy peak of Ir is 316.506 keV. 170 The gamma-ray energy peak of Tm is 84.255 keV, forming high-, medium-, and low-energy gamma-ray radionuclides. The high-purity germanium gamma-ray spectrometer in a high-temperature gas-cooled reactor burnup measurement system typically has a peak resolution better than 1.85 keV, therefore... 60 Co、 192 Ir and 170 The γ-ray energy peak of Tm has sufficient measurement discrimination.

[0135] S2, Preparation of the marking target

[0136] During normal operation of the high-temperature gas-cooled reactor (HTGR), when new conventional fuel elements (fuel elements without identifiable targets) are loaded into the reactor core daily via the fuel loading and unloading system, 10 fuel elements with identifiable codes (i.e., characteristic gamma fuel balls) are loaded at regular intervals each day, for a total of 300 fuel elements loaded over 30 consecutive days. Based on the quantity requirement of these characteristic gamma fuel balls, the fuel is loaded according to the number of identifiable targets... 59 Co contains portions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25. 191 Ir contains 0, 1, and 2 parts. 169 Tm contains 0, 1, 2, and 3 portions, resulting in a total of 300 combinations, satisfying the requirement for the number of characteristic γ-fuel sphere codes. To ensure the radioactivity range of the identification target and the standard calibration and verification sources of the high-temperature gas-cooled reactor burnup measurement system is 7.0 × 10⁻⁶, [further details are needed]. 5 ~1.0×10 10 Bq phase matching was used, and the calculated mass of one target nucleus element was approximately 0.1 mg. The maximum radioactivity of the identified target element accounts for only 0.154‰ of the total radioactivity of the fuel element, and will not have a significant impact on the radiation protection of the high-temperature gas-cooled reactor burnup measurement system.

[0137] In the identification target 59 Co is made from elemental cobalt. 191 The raw material for Ir is elemental iridium. 169 The raw material for Tm is elemental thulium. The physical state of the target is indicated by granules.

[0138] S3, Characteristic γ-fuel pellet preparation

[0139] The characteristic gamma fuel sphere includes an inner spherical fuel region and an outer shell fuel-free region, the inner spherical fuel region includes a graphite matrix and coated fuel particles, the coated fuel particles are dispersed in the graphite matrix, and the coated fuel particles contain uranium; the outer shell fuel-free region includes a graphite matrix and a marker target, the material of the graphite matrix of the inner spherical fuel region is the same as that of the outer shell fuel-free region, the marker target is added to the graphite matrix of the outer shell fuel-free region in the form of particles after being coated by a coating material, and the coating material is a matrix graphite powder which is the same as the material of the graphite matrix of the outer shell fuel-free region, the diameter of the inner spherical fuel region of the prepared characteristic gamma fuel sphere is 50 mm, and the thickness of the outer shell fuel-free region is 5 mm.

[0140] The raw material of the matrix graphite powder is 64% natural flake graphite, 16% artificial graphite and 20% phenolic resin, and is prepared by a process including kneading, extruding, crushing and screening.

[0141] The marker target is pressed on the outer shell fuel-free region by a quasi-isostatic pressing process after being coated by the coating material.

[0142] The manufacturing and detection process of the characteristic gamma fuel sphere is the same as that of the conventional fuel element (the fuel element without adding the marker target) except for adding the marker target.

[0143] S4, online identification of the characteristic gamma fuel sphere identification code

[0144] The fuel cycle of the high temperature gas cooled reactor adopts a multi-cycle operation mode of the fuel element (including the fuel element without adding the marker target and the characteristic gamma fuel sphere), and the cycle number is 15 times; the burnup of the fuel element (including the fuel element without adding the marker target and the characteristic gamma fuel sphere) discharged from the high temperature gas cooled reactor is measured by a high purity germanium gamma spectrometer, and the fuel element (including the fuel element without adding the marker target and the characteristic gamma fuel sphere) not reaching the design burnup value is reloaded into the core for recycling. When the specified burnup limit is reached, it is no longer reloaded into the reactor for reuse.

[0145] The characteristic gamma fuel sphere and the conventional fuel element (the fuel element without adding the marker target) have the same fuel cycle operation mode and burnup value measurement method, and the characteristic gamma fuel sphere is measured online, and the high purity germanium gamma spectrometer measures and records 60 Co, 192 Ir and 170 The characteristic gamma energy peaks and emission intensity combinations of Tm identify the specific identification code of the characteristic gamma fuel sphere online and non-destructively. The identification steps include:

[0146] The source term analysis and calculation of the characteristic gamma fuel sphere are performed to obtain the types, amounts and activities of radionuclides of the marker target in the characteristic gamma fuel sphere;

[0147] The preset value of the corresponding gamma ray emission intensity combination of the characteristic gamma fuel spheres characterized by the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV is calculated;

[0148] The characteristic gamma fuel spheres discharged from the high-temperature gas-cooled reactor pebble bed core are compared with the preset value of the corresponding gamma ray emission intensity combination characterized by the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV, and the identification code of the characteristic gamma fuel spheres is identified.

[0149] Embodiment 2

[0150] The embodiment provides a high-temperature gas-cooled reactor fuel element in-core fuel cycle tracing method, which comprises the following steps:

[0151] S1, the target nuclear element for identifying the target is selected as a combination of Co and Ir; 59 Co, 191 Ir.

[0152] S2, during normal operation of the high-temperature gas-cooled reactor, new conventional fuel elements are loaded into the core of the high-temperature gas-cooled reactor every day through the fuel loading and unloading system, wherein 4 fuel elements (i.e. characteristic gamma fuel spheres) with added identification codes are loaded at a certain time interval every day, and a total of 120 fuel elements are loaded for 30 consecutive days. Based on the number requirement of the characteristic gamma fuel spheres, the mass of the identification target is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 parts of Co, 59 Co, 191 Ir is 0, 1, 2 parts, a total of 120 combinations, meeting the number requirement of the characteristic gamma fuel sphere codes. The mass of 1 part of the target nuclear element is about 0.1 mg.

[0153] S3, the characteristic gamma fuel spheres are prepared: the method is the same as that in embodiment 1.

[0154] S4, online identification of the identification code of the characteristic gamma fuel spheres

[0155] The characteristic gamma fuel spheres and the conventional fuel elements (fuel elements without added identification targets) have the same fuel cycle operation mode and burnup value measurement method. While the burnup of the characteristic gamma fuel spheres is measured online, the high-purity germanium gamma spectrometer measures and records the characteristic gamma energy peaks and emission intensity combinations of 60 Co and 192 Ir, and the specific identification code of the characteristic gamma fuel spheres is identified online and non-destructively. The identification step comprises:

[0156] Source term analysis and calculation were performed on the characteristic γ-fuel spheres to obtain the types, amounts, and activities of the radionuclides in the identified target within the characteristic γ-fuel spheres.

[0157] Calculate the preset values ​​for the corresponding gamma-ray emission intensity combinations of the characteristic gamma-ray fuel sphere with characteristic energy peaks of 1173.228 keV, 1332.492 keV and 316.506 keV;

[0158] The characteristic gamma-ray emission intensity combinations of characteristic gamma-ray fuel spheres unloaded from the pebble bed core of the high-temperature gas-cooled reactor, with characteristic energy peaks of 1173.228 keV, 1332.492 keV, and 316.506 keV, are compared with preset values ​​to identify the identification codes of the characteristic gamma-ray fuel spheres.

[0159] Example 3

[0160] This embodiment provides a method for tracing the in-pile fuel cycle in a high-temperature gas-cooled reactor fuel element, including:

[0161] S1. Select the target core element of the identified target as... 59 Co、 169 A combination of two types of Tm;

[0162] S2. During normal operation of the high-temperature gas-cooled reactor (HTGR), when new conventional fuel elements are loaded into the reactor core daily via the fuel loading and unloading system, four fuel elements (i.e., characteristic gamma fuel balls) are loaded at regular intervals each day, for a total of 120 fuel elements with added identification codes over 30 consecutive days. Based on the quantity requirement of these characteristic gamma fuel balls, according to the identification target... 59 Co contains 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30 servings. 169 Tm contains 0, 1, 2, and 3 portions, resulting in a total of 120 combinations, satisfying the requirement for the number of characteristic γ-fuel spheres to be encoded. The mass of one portion of the target nucleus is approximately 0.1 mg.

[0163] S3. Preparation of characteristic γ-fuel pellets: The method is the same as in Example 1.

[0164] S4, Feature γ Fuel Ball Identification Code Online Recognition

[0165] Characteristic gamma fuel spheres and conventional fuel elements (fuel elements without a target) have the same fuel cycle operation mode and fuel consumption measurement method. While the fuel consumption of the characteristic gamma fuel spheres is measured online, a high-purity germanium gamma spectrometer measures and records the data. 60 Co and 170The characteristic gamma energy peak and emission intensity combination of Tm identifies the specific identification code of the characteristic gamma fuel sphere in line and non-destructively. The identification step comprises:

[0166] The source term analysis and calculation of the characteristic gamma fuel sphere are performed to obtain the type, amount and activity of each radionuclide of the identification target in the characteristic gamma fuel sphere;

[0167] The preset value of the corresponding gamma ray emission intensity combination of the characteristic gamma fuel sphere with 1173.228 keV, 1332.492 keV and 84.255 keV as the characteristic energy peaks is calculated;

[0168] The gamma ray emission intensity combination of the characteristic gamma fuel sphere with 1173.228 keV, 1332.492 keV and 84.255 keV as the characteristic energy peaks is compared with the preset value to identify the identification code of the characteristic gamma fuel sphere.

[0169] Embodiment 4

[0170] The embodiment provides a high-temperature gas-cooled reactor fuel element in-pile fuel cycle tracing method, comprising:

[0171] S1, the target nuclear element of the identification target is selected as a combination of 59 Co, 191 Ir, 169 Tm;

[0172] S2, the identification target is prepared

[0173] During normal operation of the high-temperature gas-cooled reactor, the fuel loading and unloading system loads new conventional fuel elements (fuel elements without added identification targets) into the core of the high-temperature gas-cooled reactor every day, wherein 9 added identification code fuel elements (i.e. characteristic gamma fuel spheres) are loaded at certain time intervals every day, and 270 added identification code fuel elements are loaded for 30 consecutive days. Based on the number requirement of the characteristic gamma fuel spheres, the amount of 59 Co contains 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 parts, 191 Ir contains 0, 1, 2 parts, 169 Tm contains 0, 1, 2 parts, a total of 270 combinations, meeting the number requirement of the characteristic gamma fuel sphere code. The mass of 1 part of the target nuclear element is about 0.1 mg.

[0174] The raw material of 59 Co in the identification target is cobalt, 191 The raw material of Ir is iridium, 169The raw material for Tm is elemental thulium. The physical state of the target is indicated by granules.

[0175] S3. Preparation of characteristic γ-fuel pellets: The method is the same as in Example 1.

[0176] S4. Online identification of fuel ball identification code with feature γ: The method is the same as in Example 1.

[0177] Example 5

[0178] This embodiment provides a method for tracing the in-core fuel cycle of a high-temperature gas-cooled reactor fuel element, including:

[0179] S1. Select the target core element of the identified target as... 59 Co、 191 Ir、 169 A combination of the three types of Tm;

[0180] S2, Preparation of the marking target

[0181] During normal operation of the high-temperature gas-cooled reactor (HTGR), when new conventional fuel elements (fuel elements without identifiable targets) are loaded into the reactor core daily via the fuel loading and unloading system, 12 identifiable fuel elements (i.e., characteristic gamma fuel balls) are loaded at regular intervals each day, for a total of 360 identifiable fuel elements (i.e., characteristic gamma fuel balls) over 30 consecutive days. Based on the quantity requirement of these characteristic gamma fuel balls, according to the number of identifiable targets... 59 Co contains 40 portions of the following: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40. 191 Ir contains 0, 1, and 2 parts. 169 Tm contains 0, 1, and 2 portions, resulting in a total of 360 combinations, satisfying the requirement for the number of characteristic γ-fuel spheres to be encoded. The mass of one portion of the target nucleus is approximately 0.1 mg.

[0182] In the identification target 59 The raw material for Co is electroplated cobalt. 191 The raw material for Ir is elemental iridium. 169 The raw material for Tm is Tm₂O₃. The physical state of the target is indicated by granules.

[0183] S3. Preparation of characteristic γ-fuel pellets: The method is the same as in Example 1.

[0184] S4. Online identification of fuel ball identification code with feature γ: The method is the same as in Example 1.

[0185] Example 6

[0186] This embodiment provides a method for in-pile fuel cycle tracing in a high-temperature gas-cooled reactor using spherical elements. The spherical elements include fuel elements and graphite spheres. The method includes:

[0187] S1. Select the target core element of the identified target as... 59 Co、 191 Ir、 169 A combination of the three types of Tm;

[0188] S2, Preparation of the marking target

[0189] During normal operation of the high-temperature gas-cooled reactor (HTGR), when new conventional fuel elements (fuel elements without identifiable targets) are loaded into the reactor core daily via the fuel loading and unloading system, 10 spherical elements with identifiable codes are loaded each day at regular intervals, for a total of 300 elements (fuel elements with identifiable codes are called characteristic gamma fuel balls, and graphite balls with identifiable codes are called characteristic gamma graphite balls) are loaded over 30 consecutive days; including 290 characteristic gamma fuel balls and 10 characteristic gamma graphite balls. Based on this requirement for the number of characteristic gamma fuel balls and characteristic gamma graphite balls, according to the identification targets... 59 Co contains portions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25. 191 Ir contains 0, 1, and 2 parts. 169 Tm contains 0, 1, 2, and 3 parts, resulting in a total of 300 combinations, which meets the coding number requirements for feature γ fuel spheres and feature γ graphite spheres.

[0190] In the identification target 59 Co is made from elemental cobalt. 191 The raw material for Ir is elemental iridium. 169 The raw material for Tm is elemental thulium. The physical state of the target is indicated by granules.

[0191] S3, preparation of characteristic γ-fuel balls and characteristic γ-graphite balls

[0192] (1) The characteristic γ-fuel sphere includes an inner spherical fuel region and an outer fuel-free region. The inner spherical fuel region includes a graphite matrix and coated fuel particles. The coated fuel particles are dispersed in the graphite matrix and contain uranium. The outer fuel-free region includes a graphite matrix and a marker target. The graphite matrix of the inner spherical fuel region is made of the same material as that of the outer fuel-free region. The marker target is added to the graphite matrix of the outer fuel-free region in the form of particles after being coated with a coating material. The coating material is the same as the graphite matrix material of the outer fuel-free region. The diameter of the inner spherical fuel region of the characteristic γ-fuel sphere is 50 mm, and the thickness of the outer fuel-free region is 5 mm.

[0193] The raw material of the matrix graphite powder is 64% natural flake graphite, 16% artificial graphite and 20% phenolic resin by mass fraction, which is prepared by a process including kneading, extruding, crushing and screening.

[0194] The identification target is coated with a coating material and then pressed on the fuel-free area of the shell by quasi-isostatic pressing.

[0195] The manufacturing and testing process of the characteristic gamma fuel pellet is the same as that of the conventional fuel element (the fuel element without the identification target) except for the addition of the identification target.

[0196] (2) Characteristic gamma graphite pellet

[0197] The identification target is coated with a coating material and then added to the graphite pellet, and the coating material is the same matrix graphite powder as that of the graphite pellet. The raw material of the matrix graphite powder is 64% natural flake graphite, 16% artificial graphite and 20% phenolic resin by mass fraction, which is prepared by a process including kneading, extruding, crushing and screening. The diameter of the prepared characteristic gamma graphite pellet is 60 mm.

[0198] The manufacturing and testing process of the characteristic gamma graphite pellet is the same as that of the conventional graphite pellet (the graphite pellet without the identification target) except for the addition of the identification target.

[0199] S4, Online identification of the characteristic gamma fuel pellet and the characteristic gamma graphite pellet

[0200] The burnup of the spherical element discharged from the high-temperature gas-cooled reactor (including the fuel element without the identification target and the characteristic gamma fuel pellet and the characteristic gamma graphite pellet) is measured by a high-purity germanium gamma spectrometer. The fuel element (including the fuel element without the identification target and the characteristic gamma fuel pellet) that does not reach the designed burnup value is refilled into the core for recycling. When the specified burnup limit is reached, it is no longer refilled into the reactor for reuse.

[0201] The characteristic gamma energy peaks of Co, Ir and Tm are measured and recorded by the high-purity germanium gamma spectrometer while measuring the burnup of the characteristic gamma fuel pellet and the characteristic gamma graphite pellet. 60 Co, 192 Ir and 170 Tm, the specific identification code of the characteristic gamma fuel pellet and the characteristic gamma graphite pellet is identified online and non-destructively. The identification steps include:

[0202] The source term analysis and calculation of the characteristic gamma fuel pellet and the characteristic gamma graphite pellet are performed to obtain the type, amount and activity of each radionuclide of the identification target in the characteristic gamma fuel pellet and the characteristic gamma graphite pellet.

[0203] The preset value of the corresponding gamma ray emission intensity combination of the characteristic gamma fuel ball and the characteristic gamma graphite ball with the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV is calculated;

[0204] The corresponding gamma ray emission intensity combination of the characteristic gamma fuel ball and the characteristic gamma graphite ball with the characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV is compared with the preset value, and the identification code of the characteristic gamma fuel ball and the characteristic gamma graphite ball is identified.

[0205] The tracing method of the fuel element in the high-temperature gas cooled reactor provided by the embodiment of the present application can obtain the circulation data of the fuel element in the reactor for multiple different periods in an online and nondestructive manner, and the measured data reflecting the randomness of the ball flow movement and the ball flow path are used to perform iterative calculation on the ball flow model of the high-temperature gas cooled reactor physical and thermal calculation software to improve and verify the core radial flow channel partition and axial fuel layering model, so that the accuracy of the high-temperature gas cooled reactor physical and thermal calculation analysis can be improved, and the ball flow modeling problem of the high-temperature gas cooled reactor in the world can be solved to a certain extent, and the safe operation of the high-temperature gas cooled reactor is ensured.

[0206] In the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can be explicitly or implicitly included at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0207] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and other terms should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0208] In this disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, the terminology "comprising" is used in the disclosure as comprising but not limited to, that is, it is open-ended and does not exclude the presence of additional features, structures, materials, or characteristics.

[0209] Although the embodiments of the present disclosure have been shown and described above, it should be understood by those having ordinary skill in the art that the above-mentioned embodiments are exemplary and should not be construed as limiting the present disclosure, and those having ordinary skill in the art can make changes, modifications, replacements, and variations to the above-mentioned embodiments within the scope of the present disclosure.

Claims

1. A method for in-pile circulation tracing of spherical elements in a high-temperature gas-cooled reactor, characterized in that, The method includes: identifying and encoding the spherical element by adding a marking target; the marking target includes a target core element. 59 Co、 191 Ir、 169 Tm contains one, two, or three combinations, and contains at least one of them. 59 Co, different identification targets include different types and / or proportions of target core elements, and the spherical elements include fuel elements and / or graphite spheres; In each of the spherical elements 59 The content of Co is 0.1 mg to N / 10 mg. 191 The content of Ir is 0mg to 0.2mg. 169 The content of Tm is 0mg to 0.3mg, and N is an integer between 2 and 41; The identification methods include: To obtain the types, amounts, and activity of each radionuclide in the target element of the spherical element; Calculate the preset values ​​for the corresponding γ-ray emission intensity combinations of the spherical element with characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV; The identification code of the spherical element is identified by comparing the combination of the corresponding gamma-ray emission intensities with characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV in the spherical element unloaded from the pebble bed core of the high-temperature gas-cooled reactor with preset values.

2. The method for in-pile circulation tracing of spherical elements in a high-temperature gas-cooled reactor according to claim 1, characterized in that, The proportions of the target core element used in the identified target are as follows: 59 Co is 1 to N parts. 191 Ir is 0-2 parts. 169 Tm is 0 to 3 parts, and N is an integer between 2 and 41.

3. The in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor according to claim 1, characterized in that, The marking target 59 The raw material for Co is selected from either elemental cobalt or electroplated cobalt. 191 The raw material for Ir is selected from one of elemental iridium or iridium-10% gold alloy. 169 The raw materials for Tm are selected from either elemental thulium or Tm2O3.

4. The in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor according to claim 1, characterized in that, The marking target can be granular, filamentous, sheet-like, metal-plated, glassy with a carrier substance, or graphite powder pressed into a tablet.

5. A method for in-pile circulation tracing of spherical elements in a high-temperature gas-cooled reactor according to any one of claims 1 to 4, characterized in that, The fuel element includes an inner spherical fuel region and a fuel-free region on the outer shell, and the marking target is added to the fuel-free region on the outer shell of the fuel element.

6. The in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor according to claim 5, characterized in that, The inner spherical fuel zone has a diameter of 50 mm, and the outer shell fuel-free zone has a thickness of 2.5–7.5 mm.

7. The in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor according to claim 5, characterized in that, The inner spherical fuel region includes a graphite matrix and coated fuel particles, the coated fuel particles being dispersed in the graphite matrix and containing uranium; the outer fuel-free region includes a graphite matrix and a marking target, the marking target being added to the graphite matrix of the outer fuel-free region, and the inner spherical fuel region is made of the same material as the graphite matrix of the outer fuel-free region.

8. The in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor according to claim 7, characterized in that, The marking target is coated with a coating material and added in the form of particles to the graphite matrix of the fuel-free area of ​​the fuel element's outer shell. The coating material is the same matrix graphite powder as the graphite matrix material of the fuel-free area of ​​the outer shell.

9. The in-pile circulation tracing method for spherical elements in a high-temperature gas-cooled reactor according to claim 8, characterized in that, The marking target is coated with a coating material and then pressed into the fuel-free area of ​​the fuel element's outer shell using a quasi-isostatic pressing process.

10. A method for in-pile circulation tracing of spherical elements in a high-temperature gas-cooled reactor according to any one of claims 1 to 4, characterized in that, The marking target is added to the graphite sphere after being coated with a coating material, which is the same matrix graphite powder as the graphite sphere.

11. The method for in-pile circulation tracing of spherical elements in a high-temperature gas-cooled reactor according to claim 1, characterized in that, The measurements were performed using a high-purity germanium gamma spectrometer within the fuel consumption measurement system.

12. A spherical element for a high-temperature gas-cooled reactor, characterized in that, A marker target is added to the spherical element, and the marker target includes a target core element. 59 Co、 191 Ir、 169 Tm contains one, two, or three combinations, and contains at least one of them. 59 Co, different identification targets include different types and / or proportions of target core elements, and the spherical element is a fuel element or a graphite sphere; The identification methods include: To obtain the types, amounts, and activity of each radionuclide in the target element of the spherical element; Calculate the preset values ​​for the corresponding γ-ray emission intensity combinations of the spherical element with characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV; The identification code of the spherical element is identified by comparing the combination of the corresponding gamma-ray emission intensities with characteristic energy peaks of 1173.228 keV, 1332.492 keV, 316.506 keV and 84.255 keV in the spherical element unloaded from the pebble bed core of the high-temperature gas-cooled reactor with preset values.

13. A spherical element for a high-temperature gas-cooled reactor according to claim 12, characterized in that, The proportions of the target core element used in the identified target are as follows: 59 Co is 1 to N parts. 191 Ir is 0-2 parts. 169 Tm is 0 to 3 parts, and N is an integer between 2 and 41.

14. A spherical element for a high-temperature gas-cooled reactor according to claim 12, characterized in that, In each of the spherical elements 59 The content of Co is 0.1 mg to N / 10 mg. 191 The content of Ir is 0mg to 0.2mg. 169 The content of Tm is 0mg to 0.3mg, and N is an integer between 2 and 41.

15. A spherical element for a high-temperature gas-cooled reactor according to claim 12, characterized in that, The marking target 59 The raw material for Co is selected from either elemental cobalt or electroplated cobalt. 191 The raw material for Ir is selected from one of elemental iridium or iridium-10% gold alloy. 169 The raw materials for Tm are selected from either elemental thulium or Tm2O3.

16. A spherical element for a high-temperature gas-cooled reactor according to claim 12, characterized in that, The marking target can be granular, filamentous, sheet-like, metal-plated, glassy with a carrier substance, or graphite powder pressed into a tablet.

17. A spherical element for a high-temperature gas-cooled reactor according to any one of claims 12 to 16, characterized in that, The fuel element includes an inner spherical fuel region and a fuel-free region on the outer shell, and the marking target is added to the fuel-free region on the outer shell of the fuel element.

18. A spherical element for a high-temperature gas-cooled reactor according to claim 17, characterized in that, The inner spherical fuel zone has a diameter of 50 mm, and the outer shell fuel-free zone has a thickness of 2.5–7.5 mm.

19. A spherical element for a high-temperature gas-cooled reactor according to claim 17, characterized in that, The inner spherical fuel region includes a graphite matrix and coated fuel particles, the coated fuel particles being dispersed in the graphite matrix and containing uranium; the outer fuel-free region includes a graphite matrix and a marking target, the marking target being added to the graphite matrix of the outer fuel-free region, and the inner spherical fuel region is made of the same material as the graphite matrix of the outer fuel-free region.

20. A spherical element for a high-temperature gas-cooled reactor according to claim 19, characterized in that, The marking target is coated with a coating material and added in the form of particles to the graphite matrix of the fuel-free area of ​​the fuel element's outer shell. The coating material is the same matrix graphite powder as the graphite matrix material of the fuel-free area of ​​the outer shell.

21. A spherical element for a high-temperature gas-cooled reactor according to claim 20, characterized in that, The marking target is coated with a coating material and then pressed into the fuel-free area of ​​the fuel element's outer shell using a quasi-isostatic pressing process.

22. A spherical element for a high-temperature gas-cooled reactor according to any one of claims 12 to 16, characterized in that, The marking target is added to the graphite sphere after being coated with a coating material, which is the same matrix graphite powder as the graphite sphere.

23. A high-temperature gas-cooled reactor system, characterized in that: Includes a spherical element for a high-temperature gas-cooled reactor according to any one of claims 12 to 22.

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