Radioisotope tracing-based fuel cladding tube surface scale on-line measuring device

Abstract

The invention relates to the cross technical field of nuclear reactor engineering and corrosion engineering, in particular to a radioactive isotope tracing-based fuel cladding tube surface scale on-line measurement device, which comprises an injection control module for injecting a radioactive 59Fe solution into a coolant and adjusting and controlling the 59Fe content by analyzing the Fe ion concentration; the test module is used for testing the surface of the fuel cladding based on the coolant injected with the radioactive 59Fe solution; and the measuring module is used for collecting the radioactive activity of 59Fe in scale generated on the surface of the fuel cladding after the test and speculating the scale mass surface density. According to the method, the content of the 59Fe in the coolant is controlled, and the radioactive activity of the 59Fe in the scale deposit on the surface of the fuel cladding is detected on line, so that the mass of the corresponding 59Fe can be accurately calculated, the scale deposit mass is speculated, the scale deposit information on the surface of a cladding pipe is obtained in real time, and the dynamic change condition of the scale deposit is reflected in time.

Description

Technical Field

[0001] The present invention relates to the intersecting technical field of nuclear reactor engineering and corrosion engineering, and in particular to an online measurement device for fouling on the surface of a fuel cladding tube based on radioactive isotope tracing. Background Art

[0002] The primary fuel cladding tubes of a pressurized water reactor (PWR) serve as the first line of defense. While preventing radioactive leakage from the core, they also transmit the large amounts of heat released by the nuclear reactions in the core. These tubes are subject to corrosion from high-temperature, high-pressure water. During long-term operation of a nuclear power plant, corrosion products accumulate on the cladding tubes. This fouling on the cladding surface leads to decreased thermal conductivity and activation of corrosion products. As the thickness of the fouling increases, thermal conductivity decreases, preventing timely removal of core heat. This leads to increased core temperature, further posing core safety concerns. Therefore, online monitoring of fuel cladding surface fouling is key to improving reactor operational safety and the service life of the cladding.

[0003] Methods for detecting fouling typically include scanning electron microscopy, capacitance, and concentration calculation methods. The scanning electron microscopy method, used to measure fouling on the surface of the primary fuel cladding of a pressurized water reactor, requires shutting down the reactor, removing the fuel cladding tubes, cutting them into sections, photographing the cross-sectional morphology with a microscope, and visually measuring the thickness of the fouling. However, this method is a destructive detection method, and the cut cladding tubes cannot continue to be used. Furthermore, only the fouling situation at a single time point can be obtained, which has certain limitations and lacks continuous detection of the fouling situation on the fuel cladding. The capacitance method involves placing a test plate on the surface of the object being tested. A certain thickness of fouling contaminates the scale line on the front of the test plate, causing a change in capacitance. The capacitance change data between the metal electrode plates is collected using a capacitance sensor detector and an LCR bridge digital detector to estimate the fouling thickness. The disadvantage is that it can only detect fouling on the surface of non-metallic materials, and the fuel cladding is a zirconium alloy, so this method is not suitable for detecting fouling on the surface of the fuel cladding. The concentration calculation method predicts the stable iron-nickel oxides formed on the cladding surface under current operating conditions by measuring the coolant pH and boron concentration. The particle size and concentration of the iron-nickel oxide particles are then calculated, and the scale thickness is then calculated using a corresponding formula. This method relies entirely on theoretical calculations. However, scale accumulation on the cladding surface is a complex behavior influenced by water chemistry, materials, and thermal hydraulics, and theoretical calculations have significant limitations in terms of reliability and applicability. Therefore, the present invention proposes an online measurement device for fuel cladding tube surface scale accumulation based on radioactive isotope tracing. Summary of the Invention

[0004] The purpose of the present invention is to provide an online measurement device for the fouling on the surface of fuel cladding tubes based on radioactive isotope tracing. 59The Fe corrosion product source is injected into the primary coolant, and the corrosion product in the fouling is detected by a scintillation detector containing NaI (Tl) crystal and a photomultiplier tube. 59 The gamma rays generated by Fe decay are collected to collect the radioactive activity of the gamma rays and estimate the fouling mass, thus realizing online monitoring of the fouling condition on the surface of the fuel cladding.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An online measurement device for fouling on the surface of a fuel cladding tube based on radioactive isotope tracing, comprising:

[0007] Injection control module, used to inject radioactivity 59 Fe solution into the coolant and analyze the Fe ion concentration 59 Fe content is regulated and controlled;

[0008] Test module for injection-based radioactivity 59 Fe solution coolant was tested on the fuel cladding surface;

[0009] The measurement module is used to collect the fouling on the surface of the fuel cladding after the test. 59 Fe radioactivity, estimated fouling mass surface density.

[0010] Optionally, the injection control module includes: a boost injection pump, a high-temperature and high-pressure circuit, a preheater, a power circulation pump, a back-pressure relief valve, and a water chemical detection unit;

[0011] The radioactivity 59 The Fe solution is injected into the high-temperature and high-pressure circuit through the boost injection pump. The coolant in the high-temperature and high-pressure circuit circulates under the drive of the power circulation pump, and the coolant is controlled by the back pressure relief valve to flow into the water chemical detection unit at a preset flow rate. The Fe ion concentration in the coolant is determined by conductivity measurement and ICP-MS analysis. The Fe ion concentration in the coolant is determined by combining the flow control of the boost injection pump with the flow control of the high-temperature and high-pressure circuit. 59 The Fe content is feedback regulated;

[0012] After the adjustment is completed, the coolant is heated to a preset temperature by the preheater and then enters the test module.

[0013] Optionally, the test module includes: a pipeline, an upper end seal, a lower end seal, a fuel cladding, and an internal heating rod, wherein the pipeline is arranged on the left and right sides, and the upper end seal and the lower end seal are arranged on the upper and lower sides to form a frame structure; the internal heating rod is placed inside the fuel cladding, and the fuel cladding is placed in the frame structure, and the upper end seal and the lower end seal are removable for placing in and taking out the fuel cladding and the internal heating rod.

[0014] Optionally, the measurement module includes: a radiation detection device, a movable guide rail and a data acquisition unit, wherein the radiation detection device is connected to the movable guide rail through a pipe seat, and is used to periodically detect the scale accumulation in different areas. 59 The gamma rays generated by Fe are processed into photoelectric signals and transmitted to the data acquisition unit to calculate 59 The radioactive activity of Fe decay and the surface density of fouling mass.

[0015] Optionally, the radiation detection device comprises: a collimator, a scintillation detector and a photomultiplier tube, wherein the fouling 59 The gamma rays generated by Fe pass through the collimator, screen out horizontal gamma rays, and then penetrate into the scintillation detector, generating fluorescent photons that are reflected to the photomultiplier tube, generating photoelectrons and multiplying and amplifying photoelectric signals.

[0016] Optionally, the data acquisition unit calculates 59 The radioactivity of Fe decay and the surface density of fouling mass include:

[0017] Calculation based on the photoelectric signal 59 The radioactivity of Fe decay, minus 59 The basic background activity of Fe decay is used to obtain the effective radioactivity;

[0018] The amount of deposition on the fuel cladding surface is calculated based on the effective radioactivity. 59 Fe mass, combined with the collimator and fuel cladding diameter, is used to estimate the fouling on the fuel cladding surface. 59 Mass areal density of Fe.

[0019] Optionally, the deposition rate on the fuel cladding surface is calculated based on the effective radioactivity. 59 Fe qualities include:

[0020]

[0021] Where W(T) is the deposition on the fuel cladding surface during the T period. 59 The total mass of Fe, m is the mass of each atom, A(t) is the effective radioactivity at time t, A(T) is the effective radioactivity during period T, is the half-life, and ln2 is the natural logarithm of 2.

[0022] Optionally, the scale accumulation on the fuel cladding surface can be estimated by combining the collimator and the fuel cladding diameter. 59 The mass density of Fe includes:

[0023]

[0024] Where w is the amount of fouling on the fuel cladding surface 59 The mass density of Fe, a is the collimator width, b is the collimator length, and d is the fuel cladding diameter.

[0025] The beneficial effects of the present invention are:

[0026] The present invention will contain radioactive elements 59 The Fe corrosion product source is injected into the primary coolant, and the corrosion product in the fouling is detected by a scintillation detector containing NaI (Tl) crystal and a photomultiplier tube. 59 The gamma rays generated by Fe decay are collected to collect the radioactive activity of gamma rays and estimate the mass of fouling. This can obtain the fouling information on the surface of the cladding tube in real time, promptly reflect the dynamic changes of fouling, and realize online monitoring of the fouling condition on the surface of the fuel cladding.

[0027] The present invention enhances the spatial flexibility of the radiation detector through the use of movable guide rails, enabling all-round detection of fuel cladding fouling. A collimator mounted in front of the scintillation detector can filter radiation entering the detector at specific angles, reducing interference from radiation in other directions on the detection area. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a schematic diagram of an online measurement device for fouling on the surface of a fuel cladding tube based on radioactive isotope tracing according to an embodiment of the present invention, wherein 1-1: radioactive isotope tracing 59 Fe solution, 1-2: Booster injection pump, 1-3: High-temperature and high-pressure circuit, 1-4: Preheater, 1-5: Power circulation pump, 1-6: Back-pressure relief valve, 1-7: Water chemical detection unit, 2-1: Test section pipeline, 2-2: Test section upper end seal, 2-3: Test section lower end seal, 2-4: Fuel cladding, 2-5: Internal heating rod, 3-1: Collimator, 3-2: NaI(Tl) crystal, 3-3: Nickel-iron alloy shield, 4-1: Photocathode, 4-2: Focusing electrode, 4-3: Dynode, 4-4: Shielding plate, 4-5: Anode, 5-1: Moving guide, 5-2: Data acquisition unit;

[0030] Figure 2 Schematic diagram of the detection area according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] This embodiment provides an online measurement device for fouling on the surface of a fuel cladding tube based on radioactive isotope tracing, comprising:

[0034] Injection control module, used to inject radioactivity 59 Fe solution into the coolant and analyze the Fe ion concentration 59 Fe content is regulated and controlled;

[0035] Test module for injection-based radioactivity 59 Fe solution coolant was tested on the fuel cladding surface;

[0036] The measurement module is used to collect the fouling on the surface of the fuel cladding after the test. 59 Fe radioactivity, estimated fouling mass surface density.

[0037] Specifically, this embodiment uses radioisotopes 59 Fe is used as a tracer element and is also a source of corrosion products in the primary coolant and fuel cladding of a pressurized water reactor. By utilizing its characteristic of fouling the surface of the fuel cladding, the constant concentration of Fe in the coolant is controlled. 59 Fe content, detection of scale 59 The radioactivity of Fe can be used to infer the surface density of fouling, thereby realizing online monitoring of fouling conditions.

[0038] Furthermore, the injection control module includes: a boost injection pump, a high-temperature and high-pressure circuit, a preheater, a power circulation pump, a back-pressure relief valve, and a water chemical detection unit;

[0039] The radioactivity 59 The Fe solution is injected into the high-temperature and high-pressure circuit through the boost injection pump. The coolant in the high-temperature and high-pressure circuit circulates under the drive of the power circulation pump, and the coolant is controlled by the back pressure relief valve to flow into the water chemical detection unit at a preset flow rate. The Fe ion concentration in the coolant is determined by conductivity measurement and ICP-MS analysis. The Fe ion concentration in the coolant is determined by combining the flow control of the boost injection pump with the flow control of the high-temperature and high-pressure circuit. 59The Fe content is feedback regulated;

[0040] After the adjustment is completed, the coolant is heated to a preset temperature by the preheater and then enters the test module.

[0041] Furthermore, the test module includes: a pipeline, an upper end seal, a lower end seal, a fuel cladding, and an internal heating rod, wherein the pipeline is arranged on the left and right sides, and the upper end seal and the lower end seal are arranged on the upper and lower sides to form a frame structure; the internal heating rod is placed inside the fuel cladding, and the fuel cladding is placed in the frame structure, and the upper end seal and the lower end seal are removable for placing in and taking out the fuel cladding and the internal heating rod.

[0042] Furthermore, the measurement module includes: a radiation detection device, a movable guide rail and a data acquisition unit, wherein the radiation detection device is connected to the movable guide rail through a pipe seat and is used to periodically detect the scale in different areas. 59 The gamma rays generated by Fe are processed into photoelectric signals and transmitted to the data acquisition unit to calculate 59 The radioactive activity of Fe decay and the surface density of fouling mass.

[0043] Furthermore, the radiation detection device includes: a collimator, a scintillation detector and a photomultiplier tube, wherein the fouling 59 The gamma rays generated by Fe pass through the collimator, screen out horizontal gamma rays, and then penetrate into the scintillation detector, generating fluorescent photons that are reflected to the photomultiplier tube, generating photoelectrons and multiplying and amplifying photoelectric signals.

[0044] Furthermore, the data acquisition unit calculates 59 The radioactivity of Fe decay and the surface density of fouling mass include:

[0045] Calculation based on the photoelectric signal 59 The radioactivity of Fe decay, minus 59 The basic background activity of Fe decay is used to obtain the effective radioactivity;

[0046] The amount of deposition on the fuel cladding surface is calculated based on the effective radioactivity. 59 Fe mass, combined with the collimator and fuel cladding diameter, is used to estimate the fouling on the fuel cladding surface. 59 Mass areal density of Fe.

[0047] Furthermore, the deposition rate on the fuel cladding surface is calculated based on the effective radioactivity. 59 Fe qualities include:

[0048]

[0049] Where W(T) is the deposition on the fuel cladding surface during the T period. 59 The total mass of Fe, m is the mass of each atom, A(t) is the effective radioactivity at time t, A(T) is the effective radioactivity during period T, is the half-life, and ln2 is the natural logarithm of 2.

[0050] Furthermore, the fouling on the fuel cladding surface was calculated by combining the collimator and the fuel cladding diameter. 59 The mass density of Fe includes:

[0051]

[0052] Where w is the amount of fouling on the fuel cladding surface 59 The mass density of Fe, a is the collimator width, b is the collimator length, and d is the fuel cladding diameter.

[0053] The following combination Figure 1 、 Figure 2 The online measurement device for fouling on the surface of a fuel cladding tube based on radioactive isotope tracing provided in this embodiment is described in detail as follows:

[0054] Injection control module includes: Radioactive 59 Fe solution 1-1, booster injection pump 1-2, high temperature and high pressure circuit 1-3, preheater 1-4, power circulation pump 1-5, back pressure relief valve 1-6, water chemical detection unit 1-7;

[0055] Constant concentration of radioactivity 59 The Fe solution 1-1 is injected into the high temperature and high pressure circuit 1-3 through the boost injection pump 1-2 as a source of corrosion products. The coolant in the high temperature and high pressure circuit 1-3 circulates under the drive of the power circulation pump 1-5. A small amount of coolant flows into the water chemical detection unit 1-7 under the control of the back pressure relief valve 1-6. The Fe ion concentration is determined by conductivity measurement and ICP-MS analysis. Combined with the flow control of the boost injection pump 1-2, the coolant in the high temperature and high pressure circuit 1-3 is controlled. 59 Feedback regulation of Fe content.

[0056] Most of the coolant in the high-temperature and high-pressure circuit 1-3 is heated to the specified temperature after passing through the preheater 1-4 and enters the test module.

[0057] The test module includes: a test section pipe 2-1, a test section upper end seal 2-2, a test section lower end seal 2-3, a fuel cladding 2-4, and an internal heating rod 2-5. The test section upper end seal 2-2 and the test section lower end seal 2-3 can be disassembled to facilitate the insertion and removal of the fuel cladding 2-4 and the internal heating rod 2-5.

[0058] The measurement module includes: a radiation detection device, a movable guide rail 5-1 and a data acquisition unit 5-2. The radiation detection device is composed of a collimator 3-1, a scintillation detector and a photomultiplier tube.

[0059] The collimator 3-1 is made of lead-tungsten alloy and is cast by closing the four sides. It is located in front of the CZT crystal and is used to limit the direction and range of the gamma rays entering the crystal.

[0060] The scintillation detector contains sodium iodide (NaI) crystal doped with thallium (Tl), namely NaI(Tl) crystal 3-2, which can generate photons under the action of gamma rays.

[0061] The photomultiplier tube is composed of a photocathode 4-1, a focusing electrode 4-2, a dynode 4-3, a shielding plate 4-4 and an anode 4-5.

[0062] The radiation detection device is also wrapped by a nickel-iron alloy barrier 3-3 on the outside, which provides a low magnetic resistance path to guide the magnetic field lines to bypass the inside of the photomultiplier tube, thereby protecting the photomultiplier tube from interference from a strong magnetic field.

[0063] The bottom of the radiation detection device is connected to the movable guide rail 5-1 through a tube seat, and is externally connected to the data acquisition unit 5-2 via a data line.

[0064] The coolant flows over the heated fuel cladding surface, and the corrosion product source term in the coolant 59 Fe fouls and deposits on the surface of the fuel cladding, and a certain thickness of Fe is produced. 59 Fe fouling.

[0065] 59 Fe undergoes β-decay (half-life is 44.495 days) and decays into 59 Co then reaches a steady state accompanied by the emission of gamma rays, releasing 56.59% of 1.0993 MeV photons and 43.21% of 1.2916 MeV photons (highly penetrating gamma rays).

[0066] On the outside of the test section pipe 2-1, a scintillation detector for detecting gamma rays is installed. 59 Fe produces high-energy gamma rays, which pass through the collimator 3-1 in front of the scintillation detector to filter out horizontal gamma rays, avoiding interference from gamma rays deposited at the upper and lower ends of the test section. After the gamma rays penetrate the NaI (Tl) crystal 3-2 in the scintillation detector, its molecules are excited by energy, and when de-excited, they produce fluorescent photons. After being reflected by the reflective layer, the photons reach the photocathode 4-1 of the photomultiplier tube, where a photoelectric effect occurs to produce photoelectrons. After passing through the focusing electrode 4-2, they are converged into a narrower beam. The dynode 4-3 performs photoelectron multiplication and amplifies the photoelectric signal. The data acquisition unit 5-2 obtains the electrical signal and infers the 59 The radioactivity of Fe decay.

[0067] Deduct the coolant when not heated 59 The basic background activity of Fe decay is used to obtain the deposition on the surface of the fuel cladding in the test section. 59 The radioactivity of Fe is calculated by the following formula: 59 Fe quality:

[0068]

[0069] Where m is the mass of each atom, A(t) is the effective radioactivity at time t, It's the half-life.

[0070] The above formula gives the deposition rate on the fuel cladding surface within the time T. 59 The total mass of Fe, which includes the decayed Fe in the fouling 59 Fe atoms and still present in the dirt 59 Number of Fe atoms

[0071] According to the fouling on the surface of the fuel cladding 59 The mass of Fe and collimator 3-1. The diameter of the fuel cladding can be used to estimate the fouling on the fuel cladding surface. 59 The mass surface density of Fe. Figure 2 As shown in FIG, assuming that the width of the collimator 3-1 is a, the length is b, and the diameter of the fuel cladding is d, the arc length of the detection area of ​​the collimator 3-1 facing the fuel cladding is:

[0072]

[0073] The area of ​​the detection area is:

[0074]

[0075] The amount of fouling per unit area in the detection area 59 The mass of Fe is:

[0076]

[0077] The above formula gives the amount of fouling calculated from the radioactivity. 59 The mass surface density of Fe. 59 The mass fraction of Fe in the fouling can be used to obtain the mass areal density of the fouling in real time. During the test, the guide rail is moved to periodically inspect the fouling conditions in different areas, providing a comprehensive analysis of the fouling status of the entire fuel cladding. Furthermore, after the test, the cladding tube can be removed for destructive testing of the surface fouling to determine the composition, density, and thickness of the fouling, allowing verification and correction of the test results.

[0078] The device proposed in this embodiment controls the 59 Fe content and the fouling on the fuel cladding surface 59 Fe radioactivity is detected online and the corresponding 59 The Fe mass can be used to estimate the fouling mass, obtain real-time information on the cladding tube surface, and promptly reflect the dynamic changes in fouling. The overall results can be corrected after the experiment to ensure the reliability and accuracy of online detection.

[0079] The device proposed in this embodiment enhances the spatial flexibility of the radiation detector by deploying movable guide rails, enabling comprehensive detection of fuel cladding fouling. A collimator mounted in front of the scintillation detector can filter radiation entering the detector at specific angles, reducing interference from radiation in other directions on the detection area.

[0080] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. An online measurement device for fouling on the surface of a fuel cladding tube based on radioactive isotope tracing, characterized in that: include: Injection control module, used to inject radioactivity 59 Fe solution into the coolant and analyze the Fe ion concentration 59 Fe content is regulated and controlled; Test module for injection-based radioactivity 59 Fe solution coolant was tested on the fuel cladding surface; The measurement module is used to collect the fouling on the surface of the fuel cladding after the test. 59 Fe radioactivity, estimated fouling mass surface density.

2. The on-line measurement device for fuel cladding tube surface fouling based on radioactive isotope tracing according to claim 1 is characterized in that: The injection control module includes: a boost injection pump, a high-temperature and high-pressure circuit, a preheater, a power circulation pump, a back-pressure relief valve, and a water chemical detection unit; The radioactivity 59 The Fe solution is injected into the high-temperature and high-pressure circuit through the boost injection pump. The coolant in the high-temperature and high-pressure circuit circulates under the drive of the power circulation pump, and the coolant is controlled by the back pressure relief valve to flow into the water chemical detection unit at a preset flow rate. The Fe ion concentration in the coolant is determined by conductivity measurement and ICP-MS analysis. The Fe ion concentration in the coolant is determined by combining the flow control of the boost injection pump with the flow control of the high-temperature and high-pressure circuit. 59 The Fe content is feedback regulated; After the adjustment is completed, the coolant is heated to a preset temperature by the preheater and then enters the test module.

3. The on-line measurement device for fuel cladding tube surface fouling based on radioactive isotope tracing according to claim 1 is characterized in that: The test module includes: a pipeline, an upper end seal, a lower end seal, a fuel cladding, and an internal heating rod, wherein the pipeline is arranged on the left and right sides, and the upper end seal and the lower end seal are arranged on the upper and lower sides to form a frame structure; the internal heating rod is placed inside the fuel cladding, and the fuel cladding is placed in the frame structure. The upper end seal and the lower end seal are removable for placing and removing the fuel cladding and the internal heating rod.

4. The on-line measurement device for fuel cladding tube surface fouling based on radioactive isotope tracing according to claim 1 is characterized in that: The measurement module includes: a radiation detection device, a movable guide rail and a data acquisition unit, wherein the radiation detection device is connected to the movable guide rail through a pipe seat and is used to periodically detect the scale accumulation in different areas. 59 The gamma rays generated by Fe are processed into photoelectric signals and transmitted to the data acquisition unit to calculate 59 The radioactive activity of Fe decay and the surface density of fouling mass.

5. The on-line measurement device for fuel cladding tube surface fouling based on radioactive isotope tracing according to claim 4 is characterized in that: The radiation detection device includes: a collimator, a scintillation detector and a photomultiplier tube, wherein the fouling 59 The gamma rays generated by Fe pass through the collimator, screen out horizontal gamma rays, and then penetrate into the scintillation detector, generating fluorescent photons that are reflected to the photomultiplier tube, generating photoelectrons and multiplying and amplifying photoelectric signals.

6. The on-line measurement device for fuel cladding tube surface fouling based on radioactive isotope tracing according to claim 4 is characterized in that: The data acquisition unit calculates 59 The radioactivity of Fe decay and the surface density of fouling mass include: Calculation based on the photoelectric signal 59 The radioactivity of Fe decay, minus 59 The basic background activity of Fe decay is used to obtain the effective radioactivity; The amount of deposition on the fuel cladding surface is calculated based on the effective radioactivity. 59 Fe mass, combined with the collimator and fuel cladding diameter, is used to estimate the fouling on the fuel cladding surface. 59 Mass areal density of Fe.

7. The on-line measurement device for fuel cladding tube surface fouling based on radioactive isotope tracing according to claim 6, characterized in that: The amount of deposition on the fuel cladding surface is calculated based on the effective radioactivity. 59 Fe qualities include: Where W(T) is the deposition on the fuel cladding surface during the T period. 59 The total mass of Fe, m is the mass of each atom, A(t) is the effective radioactivity at time t, A(T) is the effective radioactivity during period T, is the half-life, and ln2 is the natural logarithm of 2.

8. The on-line measurement device for fuel cladding tube surface fouling based on radioactive isotope tracing according to claim 7, characterized in that: Calculate the fouling on the fuel cladding surface by combining the collimator and the fuel cladding diameter 59 The mass density of Fe includes: Where w is the amount of fouling on the fuel cladding surface 59 The mass density of Fe, a is the collimator width, b is the collimator length, and d is the fuel cladding diameter.

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