Method for measuring reactor core power of sodium-cooled fast reactor

Abstract

The invention particularly relates to a sodium-cooled fast reactor core power measurement method, which comprises the following steps of: replacing a component at a reactor core power measurement position with a test component loaded with a group of detection foils, and carrying out a reactor entry irradiation test on the test component to obtain the power at the reactor core power measurement position; calculating the reactor core power according to the power of the reactor core power measurement position; and taking the average power value of each reactor core power measurement position as the reactor core power. According to the invention, the reactor core power measurement during the low-power period of the sodium-cooled fast reactor is realized.

Description

Technical Field

[0001] The invention relates to the technical field of sodium-cooled fast reactor core power measurement, in particular to a sodium-cooled fast reactor core power measurement method. Background Art

[0002] The core power measurement below the nuclear hot spot is an important physical test of sodium-cooled fast reactors. Below the nuclear hot spot, the reactor is in a low power state and the external detector cannot measure the core power. Summary of the invention

[0003] The purpose of the present invention is to provide a method for measuring the core power of a sodium-cooled fast reactor, so as to solve the problem that an external detector of a sodium-cooled fast reactor cannot measure the core power during a low power period.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for measuring core power of a sodium-cooled fast reactor comprises the following steps:

[0006] Substituting a test assembly loaded with a set of detection foils for the assembly at the core power measurement position, conducting an in-core irradiation test of the test assembly, and obtaining the power at the core power measurement position;

[0007] The core power is calculated based on the power at the core power measurement position.

[0008] As one achievable manner, the average power value of each core power measurement position is used as the core power.

[0009] As one of the feasible methods, the test assembly is put into the pile for irradiation test, including the following steps:

[0010] Select the core power measurement position;

[0011] Debugging of test equipment;

[0012] preparing detection foil; loading detection foil in irradiation tube;

[0013] Sealing welding of irradiation tubes;

[0014] Loading the irradiation tube in the test assembly;

[0015] Replace the component at the core power measurement position with the test component and perform stable low-power irradiation on the test component;

[0016] The irradiation tube in the test assembly is taken out, the detection foil in the irradiation tube is measured, and the power at the core power measurement position is calculated.

[0017] As one of the feasible methods, the detection foil in the irradiation tube is measured to calculate the power at the core power measurement position, including the following steps:

[0018] Measure the characteristic nuclide activity of the detection foil in the irradiation tube;

[0019] According to the characteristic nuclide activity of the detection foil in the irradiation tube, the characteristic nuclide reaction rate of the detection foil in the irradiation tube is calculated;

[0020] The power at the core power measurement position is calculated based on the characteristic nuclide reaction rate of the detection foil in the irradiation tube.

[0021] As one of the feasible ways, the power at the core power measurement position is calculated according to the following formula:

[0022]

[0023] Where C is the count under the characteristic γ-ray photoelectric peak of the characteristic nuclide generated after the detection foil is irradiated; Iγ is the branching ratio and efficiency corresponding to the characteristic γ-ray when the characteristic nuclide decays; ε is the efficiency of the characteristic γ-ray when the characteristic nuclide decays; λ is the decay constant of the characteristic nuclide; Y5 is 235 The yield of characteristic nuclides produced by U fission, Y8 is 238 The yield of characteristic nuclides produced by U fission; Γ is the yield of characteristic nuclides in the detection foil. 235 U enrichment; σ8 / σ5 is the concentration of U in the core 238 U and 235 U is the fission cross section ratio; T is the irradiation time of the detection foil in the core, T w To detect the cooling time of the foil outside the core, T m is the measurement time of the detection foil; f(T, T w , T m ) is the time factor; Kv is the core fission rate correction factor; Ko is the conversion zone correction factor.

[0024] As one of the feasible ways, the irradiation test of the test assembly into the pile includes the pre-irradiation test of the test assembly into the pile and the formal irradiation test of the test assembly into the pile. Before the formal irradiation test of the test assembly into the pile, the rationality of the formal irradiation test plan of the test assembly into the pile is determined through one or more pre-irradiation tests of the test assembly into the pile. The formal irradiation test plan of the test assembly into the pile includes the irradiation conditions of the test assembly and the position of the detection piece in the test assembly.

[0025] As one of the feasible ways, a pre-irradiation test of the test assembly is carried out according to the formal irradiation test plan of the test assembly; the steps of the pre-irradiation test of the test assembly are the same as those of the formal irradiation test of the test assembly, and the only difference is that the core power measurement position is different;

[0026] For the pre-irradiation test of the test assembly, a fuel assembly in the core fuel zone is selected as the core power measurement position, and a test assembly is used to replace the selected fuel assembly; for the formal irradiation test of the test assembly, each typical assembly in the core fuel zone is selected as the core power measurement position, and each selected assembly is replaced by each test assembly;

[0027] Through one or more pre-irradiation tests of the test assembly before entering the pile, adjust the formal irradiation test plan for the test assembly before entering the pile until the formal irradiation test plan for the test assembly before entering the pile is reasonable;

[0028] When the difference between the core power calculated by the pre-irradiation test of the test assembly and the actual core power is within the set range, it indicates that the formal irradiation test plan for the test assembly is reasonable;

[0029] When the difference between the core power calculated in the pre-irradiation test of the test assembly and the actual core power exceeds the set range, it indicates that the formal irradiation test plan for the test assembly is unreasonable, and the formal irradiation test plan for the test assembly is adjusted.

[0030] As one achievable manner, an irradiation tube is axially loaded in a test assembly, and a plurality of detection foils are axially loaded in the irradiation tube;

[0031] The detection foil is prepared, comprising the following steps: selecting a detection sheet with no rust and a smooth surface; firstly wrapping the detection sheet with aluminum foil, then compacting the aluminum foil with a sheet pressing device so that the aluminum foil tightly wraps the detection sheet to form a detection foil, and finally marking the detection foil with a marker pen to complete the preparation of the detection foil;

[0032] Loading the detection foil in the irradiation tube includes the following steps:

[0033] Adjust the height of the detection foil in the irradiation tube by means of positioning columns, support blocks and spacers;

[0034] After determining the number and order of positioning columns, support blocks, spacers, and detection foils, place them on the measuring ruler for measurement, and then push them into the irradiation tube through the measuring ruler track;

[0035] After the detection foil is pushed into the irradiation tube, the detection foil is filled with argon and welded inside the irradiation tube.

[0036] As one of the feasible ways, sealing welding is performed on the irradiation tube, which includes the following steps: firstly, the irradiation tube is evacuated by a vacuum pump, then helium is filled into the irradiation tube, and finally the plugging seam and the girth weld in the irradiation tube are welded by welding equipment; during the welding process, the surface of the welding area is flat, the weld is smooth, and the transition surface is round; the helium leak detection rate of the girth weld and the plugging seam meets the corresponding helium detection requirements.

[0037] As one of the feasible ways, the irradiated tube is loaded in the test assembly by means of an irradiated tube gripper; the irradiated tube gripper comprises a silo, a gripper and an electrical cabinet; the gripper is installed in the silo, and the bottom of the silo is open; the electrical cabinet is electrically connected to the gripper to drive the gripper to grab the irradiated tube; a weighing sensor is arranged on the gripper;

[0038] Loading the irradiation tube into the test assembly includes the following steps:

[0039] The electrical cabinet drives the gripper to grab the irradiated tube; the electrical cabinet determines whether the gripper has completed the grabbing action of the irradiated tube through the weight value of the weighing sensor;

[0040] The silo is connected to the inner flange of the test assembly conversion barrel to form a sealed space;

[0041] The electrical cabinet drives the gripper to send the irradiation tube into the test assembly in the test assembly conversion barrel; the electrical cabinet determines whether the gripper has completed the action of sending the irradiation tube into the test assembly through the weight value of the weighing sensor;

[0042] When the gripper grabs the irradiated tube and puts it into the test assembly, the electrical cabinet determines whether the gripper is stuck by the change in the weight value of the weighing sensor.

[0043] As one possible implementation, both the test assembly and the irradiation tube are marked with numbers, and a one-to-one correspondence is established between the test assembly and the irradiation tube through the numbers.

[0044] As one of the feasible methods, a test assembly is used to replace the assembly at the core power measurement position, and the test assembly is subjected to stable low-power irradiation, including the following steps:

[0045] Replace the assembly at the core power measurement location with the test assembly;

[0046] The reactor operates stably in critical state for 2-6 hours, and the neutron continuous irradiation test components in the reactor;

[0047] After the reactor has been operating stably in a critical state for 2-6 hours, the reactor is stopped and the test assembly is removed and cooled in the test assembly conversion cylinder for 72 hours.

[0048] As one of the feasible methods, the irradiation tube in the test assembly is taken out by the irradiation tube gripper; the characteristic nuclide activity of the detection foil in the irradiation tube is measured by the automatic sample changing device;

[0049] The automatic sample changing equipment includes an automatic sample changing robot and a high purity germanium spectrometer; the high purity germanium spectrometer is used to measure the characteristic nuclide activity of the detection foil in the irradiation tube; the automatic sample changing robot is used to replace the irradiation tube on the high purity germanium spectrometer;

[0050] Take out the irradiation tube in the test assembly and measure the characteristic nuclide activity of the detection foil in the irradiation tube, including the following steps:

[0051] Before measuring the detection foil, the irradiation tube is taken out from the test assembly by the irradiation tube gripper; the irradiation tube is placed in the corresponding sample bottle by the automatic sample changer robot; there is a QR code at the bottom of the sample bottle, which contains the following information: sample bottle number and the type of detection foil in the sample bottle; the automatic sample changer robot recognizes the QR code at the bottom of the sample bottle, grabs the corresponding irradiation tube and places it in the sample bottle;

[0052] When the detection foil is automatically measured, the automatic sample changing robot places the sample bottles on the high-purity germanium spectrometer in the low-background lead chamber in a certain order; the high-purity germanium spectrometer measures the activity of the characteristic nuclides in the detection foil;

[0053] After the automatic sample changing robot completes the measurement of the detection foil in the previous sample bottle, it takes the previous sample bottle out of the high-purity germanium spectrometer and then places the next sample bottle into the high-purity germanium spectrometer. The high-purity germanium spectrometer measures the detection foil in the next sample bottle, thus realizing uninterrupted measurement of the detection foil.

[0054] As one possible implementation method, the irradiation tube is taken out from the test assembly by using the irradiation tube gripper, which includes the following steps:

[0055] The silo is connected to the inner flange of the test assembly conversion barrel to form a sealed space;

[0056] The electrical cabinet drives the gripper to take out the irradiation tube from the test assembly in the test assembly conversion barrel; the electrical cabinet determines whether the gripper has completed the action of taking out the irradiation tube from the test assembly through the weight value of the weighing sensor;

[0057] When the gripper is removing the irradiation tube from the test assembly, the electrical cabinet determines whether the gripper is stuck by the change in the weight value of the weighing sensor to prevent the gripper from getting stuck.

[0058] As one of the feasible ways, the test equipment debugging includes tablet pressing device debugging, welding equipment debugging, silo air tightness debugging, weighing sensor weight calibration, automatic sample changing robot debugging and high purity germanium spectrometer debugging.

[0059] As one of the feasible ways, the debugging of high purity germanium spectrometer includes energy calibration curve calibration, efficiency calibration curve calibration, characteristic nuclide library data update, measurement time of each type of detector piece, measurement height of each type of detector piece and characteristic ray energy of each type of detector piece;

[0060] A multi-nuclide source is used to calibrate the energy calibration curve and efficiency calibration curve of the high-purity germanium spectrometer. The characteristic rays generated by the multi-nuclide source cover all characteristic rays generated by all characteristic nuclides in all detection slices, and the activity of the multi-nuclide source covers the activity of all characteristic nuclides in all detection slices.

[0061] The multi-nuclide source includes a point source and a multi-nuclide water source; the point source and the multi-nuclide water source are selected to jointly calibrate the energy calibration curve of the high-purity germanium spectrometer; the point source is selected to calibrate the efficiency calibration curve of the high-purity germanium spectrometer.

[0062] Beneficial technical effects of the present invention:

[0063] The sodium-cooled fast reactor core power measurement method of the present invention has been verified through engineering field tests and realizes the core power measurement of the sodium-cooled fast reactor during low power. By comparing the measured core power with the theoretical core power, the safety and correctness of the core design can be verified, and a reference can be provided for nuclear hot spot measurement and thermal balance test. A single test assembly irradiation test can obtain multiple core data of the core power level. DETAILED DESCRIPTION

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0065] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0066] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and specific embodiments.

[0067] This embodiment provides a method for measuring core power of a sodium-cooled fast reactor, comprising the following steps:

[0068] The test assembly loaded with the detection foil is used to replace the assembly at the core power measurement position, and an irradiation test of the test assembly is carried out to obtain the power at the core power measurement position;

[0069] The core power is calculated based on the power at the core power measurement position.

[0070] In this embodiment, as one of the achievable methods, the average power of each core power measurement position is used as the core power.

[0071] The difficulty of measuring the core power by the test assembly irradiation test is that the test assembly irradiation test process is complicated. In this embodiment, as one of the feasible methods, the test assembly irradiation test includes the following steps:

[0072] Select the core power measurement position;

[0073] Debugging of test equipment;

[0074] preparing detection foil; loading detection foil in irradiation tube;

[0075] Sealing welding of irradiation tubes;

[0076] Loading the irradiation tube in the test assembly;

[0077] Replace the component at the core power measurement position with the test component and perform stable low-power irradiation on the test component;

[0078] The irradiation tube in the test assembly is taken out, the detection foil in the irradiation tube is measured, and the power at the core power measurement position is calculated.

[0079] In this embodiment, as one of the achievable methods, measuring the detection foil in the irradiation tube and calculating the power at the core power measurement position include the following steps:

[0080] Measure the characteristic nuclide activity of the detection foil in the irradiation tube;

[0081] According to the characteristic nuclide activity of the detection foil in the irradiation tube, the characteristic nuclide reaction rate of the detection foil in the irradiation tube is calculated;

[0082] The power at the core power measurement position is calculated based on the characteristic nuclide reaction rate of the detection foil in the irradiation tube.

[0083] In this embodiment, as one of the achievable methods, the power at the core power measurement position is calculated according to the following formula:

[0084]

[0085] Among them, C is the characteristic nuclide produced after the detection foil is irradiated 140 The photoelectric peak area of ​​the characteristic gamma ray of La is measured by a high-purity germanium spectrometer; Iγ is the characteristic nuclide measured by the high-purity germanium spectrometer 140 The peak ratio of La's characteristic gamma rays is measured by a high-purity germanium spectrometer; characteristic nuclides 140 The peak ratio of La emitting 1596KeV photons is 95.6%; ε is the characteristic nuclide measured by high-purity germanium spectrometer 140 The efficiency of La's characteristic γ-ray is provided by the high-purity germanium spectrometer when it leaves the factory; ce Characteristic nuclide 140The decay constant of La; Y5 is 235 Characteristic nuclides produced by U fission 140 The output of La, Y8 is 238 Characteristic nuclides produced by U fission 143 The yield of Ce is obtained by querying the nuclide library ENDF; Γ is the yield of Ce in the detection foil. 235 U enrichment; σ8 / σ5 is the concentration of U in the core 238 U and 235 The fission cross section ratio of U is obtained by querying the nuclide library ENDF; T is the irradiation time of the detection foil in the core, T w To detect the cooling time of the foil outside the core, T m is the measurement time of the detection foil; f(T, T w , T m ) is the time factor, K v is the core fission rate correction factor; K o is the correction coefficient of the conversion zone; η is the characteristic nuclide 140 The photoelectric peak efficiency of the characteristic rays of La is measured by a high-purity germanium spectrometer; τ is the system dead time during measurement by the high-purity germanium spectrometer.

[0086] In this embodiment, as one of the possible implementation methods, the characteristic nuclide 143 The characteristic gamma ray of Ce is 293keV; the characteristic nuclide 140 The characteristic gamma ray of La is 1596Ke; the characteristic nuclide 140 The peak ratio of La when emitting 1596 KeV photons is 95.6%.

[0087] In order to ensure that the subsequent formal irradiation test of the test assembly into the pile can be carried out smoothly, it is necessary to conduct a pre-irradiation test of the test assembly into the pile to conduct a preliminary verification of the formal irradiation test plan of the test assembly into the pile. In this embodiment, as one of the feasible methods, the irradiation test of the test assembly into the pile includes a pre-irradiation test of the test assembly into the pile and a formal irradiation test of the test assembly into the pile; before the formal irradiation test of the test assembly into the pile, one or more pre-irradiation tests of the test assembly into the pile are conducted to determine the rationality of the formal irradiation test plan of the test assembly into the pile; the formal irradiation test plan of the test assembly into the pile includes the irradiation conditions of the test assembly and the position of the detection piece in the test assembly.

[0088] In this embodiment, as one of the achievable methods, a pre-irradiation test of the test assembly is performed according to the formal irradiation test plan of the test assembly; the steps of the pre-irradiation test of the test assembly are the same as those of the formal irradiation test of the test assembly, and the only difference is that the core power measurement position is different;

[0089] For the pre-irradiation test of the test assembly, a fuel assembly in the core fuel zone is selected as the core power measurement position, and a test assembly is used to replace the selected fuel assembly; for the formal irradiation test of the test assembly, each typical assembly in the core fuel zone is selected as the core power measurement position, and each selected assembly is replaced by each test assembly;

[0090] Through one or more pre-irradiation tests of the test assembly before entering the pile, adjust the formal irradiation test plan for the test assembly before entering the pile until the formal irradiation test plan for the test assembly before entering the pile is reasonable;

[0091] When the difference between the core power calculated by the pre-irradiation test of the test assembly and the actual core power is within the set range, it indicates that the formal irradiation test plan for the test assembly is reasonable;

[0092] When the difference between the core power calculated in the pre-irradiation test of the test assembly and the actual core power exceeds the set range, it indicates that the formal irradiation test plan for the test assembly is unreasonable, and the formal irradiation test plan for the test assembly is adjusted.

[0093] In this embodiment, as one of the achievable ways, one irradiation tube is axially loaded in one test assembly, and a plurality of detection foils are axially loaded in one irradiation tube;

[0094] The detection foil is prepared, comprising the following steps: selecting a detection sheet with no rust and a smooth surface; firstly wrapping the detection sheet with aluminum foil, then compacting the aluminum foil with a sheet pressing device so that the aluminum foil tightly wraps the detection sheet to form a detection foil, and finally marking the detection foil with a marker pen to complete the preparation of the detection foil;

[0095] Loading the detection foil in the irradiation tube includes the following steps:

[0096] Adjust the height of the detection foil in the irradiation tube by means of positioning columns, support blocks and spacers to ensure that the detection foil is in a suitable position in the irradiation tube for irradiation;

[0097] After determining the number and order of positioning columns, support blocks, spacers, and detection foils, place them on the measuring ruler for measurement, and then push them into the irradiation tube through the measuring ruler track;

[0098] After the detection foil is pushed into the irradiation tube, the detection foil is filled with argon and welded inside the irradiation tube to prevent oxidation of the detection foil from affecting the test results.

[0099] In this embodiment, as one of the feasible methods, the irradiation tube is sealed and welded, including the following steps: first, the irradiation tube is evacuated by a vacuum pump, then helium is filled into the irradiation tube, and finally the plugging seam and the girth weld in the irradiation tube are welded by welding equipment; during the welding process, the surface of the welding area is flat, the weld is smooth, and the transition surface is smooth; the helium leak detection rate of the girth weld and the plugging seam meets the corresponding helium detection requirements.

[0100] In this embodiment, as one of the feasible ways, the irradiated tube is loaded in the test assembly by means of an irradiated tube gripper; the irradiated tube gripper comprises a silo, a gripper and an electrical cabinet; the gripper is installed in the silo, and the bottom of the silo is open; the electrical cabinet is electrically connected to the gripper to drive the gripper to grab the irradiated tube; a weighing sensor is arranged on the gripper;

[0101] Loading the irradiation tube into the test assembly includes the following steps:

[0102] The electrical cabinet drives the gripper to grab the irradiated tube; the electrical cabinet determines whether the gripper has completed the grabbing action of the irradiated tube through the weight value of the weighing sensor;

[0103] The silo is connected to the inner flange of the test assembly conversion barrel to form a sealed space;

[0104] The electrical cabinet drives the gripper to send the irradiation tube into the test assembly in the test assembly conversion barrel; the electrical cabinet determines whether the gripper has completed the action of sending the irradiation tube into the test assembly through the weight value of the weighing sensor;

[0105] When the gripper grabs the irradiated tube and puts it into the test assembly, the electrical cabinet determines whether the gripper is stuck by the change in the weight value of the weighing sensor to prevent the gripper from getting stuck.

[0106] In this embodiment, as one of the feasible ways, numbers are marked on both the test assembly and the irradiation tube, and a one-to-one correspondence is established between the test assembly and the irradiation tube through the numbers to avoid mismatching between the test assembly and the irradiation tube.

[0107] In order to ensure the accuracy of the core power value measured by the test assembly in-core irradiation test, it is necessary to irradiate the test assembly during the stable operation of the reactor critical state. In this embodiment, as one of the feasible methods, the test assembly is used to replace the assembly at the core power measurement position, and the test assembly is irradiated at a stable low power, including the following steps:

[0108] Replace the assembly at the core power measurement location with the test assembly;

[0109] The reactor operates stably in critical state for 2-6 hours, and the neutron continuous irradiation test components in the reactor;

[0110] After the reactor has been operating stably in the critical state for 2-6 hours, the reactor is stopped and the test assembly is taken out and cooled in the test assembly conversion cylinder for 72 hours to reduce the impact of short-lived nuclides on the test results and reduce the radiation dose of the test personnel.

[0111] In this embodiment, as one of the achievable methods, the critical state of the reactor is less than 0.01% of full power.

[0112] In this embodiment, as one of the achievable methods, the irradiation tube in the test assembly is taken out by the irradiation tube gripper; the detection foil in the irradiation tube is measured by the automatic sample changing device;

[0113] The automatic sample changing equipment includes an automatic sample changing robot and a high-purity germanium spectrometer; the high-purity germanium spectrometer is used to measure the characteristic nuclide activity of the detection foil in the irradiation tube; the automatic sample changing robot is used to replace the irradiation tube on the high-purity germanium spectrometer, effectively reducing the radiation dose of personnel;

[0114] Take out the irradiation tube in the test assembly and measure the detection foil in the irradiation tube, including the following steps:

[0115] Before measuring the detection foil, the irradiation tube is taken out from the test assembly by the irradiation tube gripper; the irradiation tube is placed in the corresponding sample bottle by the automatic sample changing robot; there is a QR code at the bottom of the sample bottle, which contains the following information: the sample bottle number and the type of detection foil in the sample bottle; the automatic sample changing robot recognizes the QR code at the bottom of the sample bottle, grabs the corresponding irradiation tube and places it in the sample bottle;

[0116] When the detection foil is automatically measured, the automatic sample changing robot places the sample bottles on the high purity germanium spectrometer in the low background lead chamber in a certain order; the high purity germanium spectrometer measures the characteristic nuclide activity of the detection foil in the irradiation tube;

[0117] After the automatic sample changing robot completes the measurement of the detection foil in the previous sample bottle, it takes the previous sample bottle out of the high-purity germanium spectrometer and then places the next sample bottle into the high-purity germanium spectrometer. The high-purity germanium spectrometer measures the detection foil in the next sample bottle, thus realizing uninterrupted measurement of the detection foil.

[0118] During the automatic measurement of the detection piece, an automatic sample changing device is used to realize uninterrupted measurement of the detection piece, thereby reducing the radiation dose generated by the detection piece to the test personnel.

[0119] In this embodiment, as one of the achievable methods, taking out the irradiation tube from the test assembly by using the irradiation tube gripper includes the following steps:

[0120] The silo is connected to the inner flange of the test assembly conversion barrel to form a sealed space;

[0121] The electrical cabinet drives the gripper to take out the irradiation tube from the test assembly in the test assembly conversion barrel; the electrical cabinet determines whether the gripper has completed the action of taking out the irradiation tube from the test assembly through the weight value of the weighing sensor;

[0122] When the gripper is removing the irradiation tube from the test assembly, the electrical cabinet determines whether the gripper is stuck by the change in the weight value of the weighing sensor to prevent the gripper from getting stuck.

[0123] The irradiation test of test components entering the pile involves many equipment and links and complicated steps. It is necessary to debug each device separately in advance to ensure that the irradiation test of test components entering the pile can proceed smoothly.

[0124] In this embodiment, as one of the feasible ways, the test equipment debugging includes tablet pressing device debugging, welding equipment debugging, silo air tightness debugging, weighing sensor weight calibration, automatic sample changing robot debugging and high purity germanium spectrometer debugging.

[0125] In this embodiment, as one of the feasible methods, the air tightness of the silo is debugged to prevent the gas in the test component conversion barrel from leaking through the flange connection between the silo and the test component conversion barrel, ensuring that the leakage rate of the flange connection between the silo and the test component conversion barrel meets the requirements.

[0126] In this embodiment, as one of the feasible methods, the weight of the weighing sensor is calibrated to ensure the accuracy of the weight value of the weighing sensor.

[0127] In this embodiment, as one of the feasible ways, the automatic sample changing robot is debugged to ensure that the automatic sample changing robot can accurately identify the QR code at the bottom of the sample bottle, accurately grab the sample bottle and place it into the high-purity germanium spectrometer in the lead chamber and continuously measure the detection foil.

[0128] In this embodiment, as one of the achievable methods, the debugging of the high-purity germanium spectrometer includes energy calibration curve calibration, efficiency calibration curve calibration, characteristic nuclide library data update, measurement time of each type of detection piece, measurement height of each type of detection piece and characteristic ray energy of each type of detection piece;

[0129] A multi-nuclide source is used to calibrate the energy calibration curve and efficiency calibration curve of the high-purity germanium spectrometer. The characteristic rays generated by the multi-nuclide source cover all characteristic rays generated by all characteristic nuclides in all detection slices, and the activity of the multi-nuclide source covers the activity of all characteristic nuclides in all detection slices.

[0130] The multi-nuclide source includes a point source and a multi-nuclide water source; the point source and the multi-nuclide water source are selected to jointly calibrate the energy calibration curve of the high-purity germanium spectrometer; the point source is selected to calibrate the efficiency calibration curve of the high-purity germanium spectrometer.

[0131] The multi-nuclide water source contains multiple radionuclides and produces many characteristic rays, which is suitable for the energy calibration curve calibration of the high-purity germanium spectrometer; because the multi-nuclide water source is contained in a container, it is not suitable for the efficiency calibration curve calibration of the high-purity germanium spectrometer due to the influence of the multi-nuclide water source volume; the point source has a small volume, and in addition to being used for the energy calibration curve calibration of the high-purity germanium spectrometer, it can also be used for the efficiency calibration curve calibration of the high-purity germanium spectrometer at different heights. The debugging of the high-purity germanium spectrometer ensures that the automatic sample changer can measure data that meets the requirements during the test.

[0132] In this embodiment, as one of the feasible ways, the point sources include 60CO, 241Am, 137Se and 152Eu.

[0133] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for measuring core power of a sodium-cooled fast reactor, characterized in that: The steps include: Substituting a test assembly loaded with a set of detection foils for an assembly at a core power measurement position, conducting an in-core irradiation test of the test assembly, and obtaining the power at the core power measurement position; The core power is calculated based on the power at the core power measurement position; The average power of each core power measurement position is taken as the core power.

2. The method for measuring core power of a sodium-cooled fast reactor according to claim 1, characterized in that: The test assembly irradiation test includes the following steps: Select the core power measurement position; Debugging of test equipment; preparing detection foil; loading detection foil in irradiation tube; Sealing welding of irradiation tubes; Loading the irradiation tube in the test assembly; Replace the component at the core power measurement position with the test component and perform stable low-power irradiation on the test component; The irradiation tube in the test assembly is taken out, the detection foil in the irradiation tube is measured, and the power at the core power measurement position is calculated.

3. The method for measuring core power of a sodium-cooled fast reactor according to claim 2, characterized in that: Measuring the detection foil in the irradiation tube and calculating the power at the core power measurement position includes the following steps: Measure the characteristic nuclide activity of the detection foil in the irradiation tube; According to the characteristic nuclide activity of the detection foil in the irradiation tube, the characteristic nuclide reaction rate of the detection foil in the irradiation tube is calculated; The power at the core power measurement position is calculated based on the characteristic nuclide reaction rate of the detection foil in the irradiation tube.

4. The method for measuring core power of a sodium-cooled fast reactor according to claim 3, characterized in that: The power at the core power measurement position is calculated according to the following formula: Where C is the count under the characteristic γ-ray photoelectric peak of the characteristic nuclide generated after the detection foil is irradiated; Iγ is the branching ratio and efficiency corresponding to the characteristic γ-ray when the characteristic nuclide decays; ε is the efficiency of the characteristic γ-ray when the characteristic nuclide decays; λ is the decay constant of the characteristic nuclide; Y5 is 235 The yield of characteristic nuclides produced by U fission, Y8 is 238 The yield of characteristic nuclides produced by U fission; Γ is the yield of characteristic nuclides in the detection foil. 235 U enrichment; σ8 / σ5 is the concentration of U in the core 238 U and 235 U is the fission cross section ratio; T is the irradiation time of the detection foil in the core, T w To detect the cooling time of the foil outside the core, T m is the measurement time of the detection foil; f(T, T w , T m ) is the time factor; Kv is the core fission rate correction factor; Ko is the conversion zone correction factor.

5. The method for measuring core power of a sodium-cooled fast reactor according to claim 2, characterized in that: An irradiation tube is axially loaded in one test assembly, and a plurality of detection foils are axially loaded in one irradiation tube; The detection foil is prepared, comprising the following steps: selecting a detection sheet with no rust and a smooth surface; firstly wrapping the detection sheet with aluminum foil, then compacting the aluminum foil with a sheet pressing device so that the aluminum foil tightly wraps the detection sheet to form a detection foil, and finally marking the detection foil with a marker pen to complete the preparation of the detection foil; Loading the detection foil in the irradiation tube includes the following steps: Adjust the height of the detection foil in the irradiation tube by means of positioning columns, support blocks and spacers; After determining the number and order of positioning columns, support blocks, spacers, and detection foils, place them on the measuring ruler for measurement, and then push them into the irradiation tube through the measuring ruler track; After the detection foil is pushed into the irradiation tube, the detection foil is filled with argon and welded inside the irradiation tube.

6. The method for measuring core power of a sodium-cooled fast reactor according to claim 2, characterized in that: Sealing welding of the irradiation tube includes the following steps: firstly, evacuating the irradiation tube by a vacuum pump, then filling the irradiation tube with helium, and finally welding the plugging seam and the girth weld in the irradiation tube by welding equipment; during the welding process, the surface of the welding area is flat, the weld is smooth, and the transition surface is round; the helium leak detection rate of the girth weld and the plugging seam meets the corresponding helium detection requirements.

7. The method for measuring core power of a sodium-cooled fast reactor according to claim 2, characterized in that: The irradiated tube is loaded into the test assembly through the irradiated tube gripper; the irradiated tube gripper comprises a silo, a gripper and an electrical cabinet; the gripper is installed in the silo, and the bottom of the silo is open; the electrical cabinet is electrically connected to the gripper to drive the gripper to grab the irradiated tube; a weighing sensor is provided on the gripper; Loading the irradiation tube into the test assembly includes the following steps: The electrical cabinet drives the gripper to grab the irradiated tube; the electrical cabinet determines whether the gripper has completed the grabbing action of the irradiated tube through the weight value of the weighing sensor; The silo is connected to the inner flange of the test assembly conversion barrel to form a sealed space; The electrical cabinet drives the gripper to send the irradiation tube into the test assembly in the test assembly conversion barrel; the electrical cabinet determines whether the gripper has completed the action of sending the irradiation tube into the test assembly through the weight value of the weighing sensor; When the gripper grabs the irradiated tube and puts it into the test assembly, the electrical cabinet determines whether the gripper is stuck by the change in the weight value of the weighing sensor.

8. The method for measuring core power of a sodium-cooled fast reactor according to claim 2, characterized in that: The test assembly is used to replace the assembly at the core power measurement position, and the test assembly is subjected to stable low-power irradiation, including the following steps: Replace the assembly at the core power measurement location with the test assembly; The reactor operates stably in critical state for 2-6 hours, and the neutron continuous irradiation test components in the reactor; After the reactor has been operating stably in a critical state for 2-6 hours, the reactor is stopped and the test assembly is removed and cooled in the test assembly conversion cylinder for 72 hours.

9. The method for measuring core power of a sodium-cooled fast reactor according to claim 2, characterized in that: Take out the irradiation tube in the test assembly through the irradiation tube gripper; measure the characteristic nuclide activity of the detection foil in the irradiation tube through the automatic sample changing device; Automatic sample changing equipment includes automatic sample changing robot and high purity germanium spectrometer; The high-purity germanium spectrometer is used to measure the characteristic nuclide activity of the detection foil in the irradiation tube; the automatic sample changing robot is used to replace the irradiation tube on the high-purity germanium spectrometer; Take out the irradiation tube in the test assembly and measure the characteristic nuclide activity of the detection foil in the irradiation tube, including the following steps: Before measuring the detection foil, the irradiation tube is taken out from the test assembly by the irradiation tube gripper; the irradiation tube is placed in the corresponding sample bottle by the automatic sample changer robot; there is a QR code at the bottom of the sample bottle, which contains the following information: sample bottle number and the type of detection foil in the sample bottle; the automatic sample changer robot recognizes the QR code at the bottom of the sample bottle, grabs the corresponding irradiation tube and places it in the sample bottle; When the detection foil is automatically measured, the automatic sample changing robot places the sample bottles on the high-purity germanium spectrometer in the low-background lead chamber in a certain order; the high-purity germanium spectrometer measures the activity of the characteristic nuclides in the detection foil; After the automatic sample changing robot completes the measurement of the detection foil in the previous sample bottle, it takes the previous sample bottle out of the high-purity germanium spectrometer and then places the next sample bottle into the high-purity germanium spectrometer. The high-purity germanium spectrometer measures the detection foil in the next sample bottle, thus realizing uninterrupted measurement of the detection foil.

10. The method for measuring core power of a sodium-cooled fast reactor according to claim 2, characterized in that: Test equipment debugging, including high-purity germanium spectrometer debugging; high-purity germanium spectrometer debugging includes energy calibration curve calibration, efficiency calibration curve calibration, characteristic nuclide library data update, measurement time of each type of detection piece, measurement height of each type of detection piece and characteristic ray energy of each type of detection piece; multi-nuclide source is selected to perform energy calibration curve and efficiency calibration curve calibration of high-purity germanium spectrometer, the characteristic rays generated by multi-nuclide source cover all characteristic rays generated by all characteristic nuclides in all detection pieces, and the activity of multi-nuclide source covers the activity of all characteristic nuclides in all detection pieces; multi-nuclide source includes point source and multi-nuclide water source; point source and multi-nuclide water source are selected to perform energy calibration curve calibration of high-purity germanium spectrometer together; A point source is used to calibrate the efficiency calibration curve of the high purity germanium spectrometer.

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