WO2023241468A1

WO2023241468A1 - Online measurement system for radiation source term of pipeline of high-temperature gas-cooled reactor fuel loading and unloading system

Info

Publication number: WO2023241468A1
Application number: PCT/CN2023/099293
Authority: WO
Inventors: 方晟; 张作义; 董玉杰; 熊威
Original assignee: 清华大学
Priority date: 2022-06-17
Filing date: 2023-06-09
Publication date: 2023-12-21
Also published as: CN114966811A

Abstract

An online measurement system for a radiation source term of a pipeline (4) of a high-temperature gas-cooled reactor fuel loading and unloading system, comprising: a CZT detection unit, configured to detect deposited radioactive substances in a pipeline (4); a scanning and rotating mechanism, provided outside the pipeline (4) and used for bearing the CZT detection unit; and a control processing unit, configured to control the CZT detection unit to realize scanning and rotating detection in the radial direction and the axial direction of the pipeline (4) along the scanning and rotating mechanism, so as to complete online measurement of a radiation source term of the pipeline (4). The source term information of the system under different working conditions is obtained by performing in-situ measurement on the source term of the pipeline (4).

Description

Online measurement system for radiation source items in pipelines of high-temperature gas-cooled reactor fuel loading and unloading systems

Technical field

The invention relates to an online measurement system for pipe radiation source items in a high-temperature gas-cooled reactor fuel loading and unloading system, and relates to the technical field of nuclear radiation.

Background technique

High-temperature gas-cooled reactors adopt a fuel cycle method of online non-stop refueling, which makes the radiation field distribution, equipment and pipeline layout in the plant significantly different from that of pressurized water reactors. Therefore, the design of the online measurement system for radiation source items in the fuel loading and unloading system pipelines cannot be applied to existing mature products and equipment, and must be specially designed according to the characteristics of high-temperature reactors.

Currently, there is a lack of online measurement equipment, so the pipe can only be cut open for sampling and sent to the laboratory for analysis. This method not only causes pipeline damage, but also fails to obtain radiation source distribution information at the location of interest in the pipeline.

Contents of the invention

In view of the above problems, the object of the present invention is to provide an online measurement system for pipeline radiation source items of a high-temperature gas-cooled reactor fuel loading and unloading system that can perform in-situ measurement of pipeline source items.

In order to achieve the above-mentioned object of the invention, the present invention provides a technical solution: an online measurement system for pipeline radiation source items of a high-temperature gas-cooled reactor fuel loading and unloading system. The system includes:

CZT detection unit, used to detect radioactive materials deposited in pipelines;

A scanning rotation mechanism is provided outside the pipeline and used to carry the CZT detection unit;

A control processing unit is used to control the CZT detection unit to implement scanning rotation detection along the radial and axial directions of the pipeline along the scanning rotation mechanism to complete online measurement of the pipeline radiation source item.

Further, the CZT detection unit adopts a CZT hemispheric detector.

Further, the scanning rotation mechanism includes two semicircular guide rails and two linear guide rails. The two linear guide rails are arranged in parallel and spaced apart along the axial direction of the pipeline; the two semicircular guide rails are located between the two linear guide rails. The inner side is relatively arranged in an arc-shaped track and can move linearly along the straight track; the CZT hemispheric detector is slidably arranged on each semi-circular guide rail through a slider, and the control processing unit controls the CZT hemisphere The shape detector moves along the linear guide rail and arc-shaped track to achieve scanning and rotation detection along the radial and axial directions of the pipeline.

Further, a dose detection unit is also provided on the slider of each semicircular guide rail. The control processing unit obtains the data detected by the dose detection unit. When the dose rate detected by the dose detection unit is greater than the set When the value is set, the control processing unit controls the CZT hemispherical detector to stop collecting.

Furthermore, a shielding body is also provided on the slider of each semicircular guide rail. The shielding body is set at the front end of the CZT hemispherical detector through a pin. When the dose detection unit detects that the dose exceeds the standard , the control processing unit controls the shielding body to be rotated and placed at the front end of the CZT hemispherical detector to reduce the radiation exposure received by the CZT hemispherical detector.

Further, the online measurement system also includes a data processing unit for analyzing and processing the detection results of the CZT detection unit.

Further, the data processing unit includes a measurement and analysis system; the measurement and analysis system includes a data acquisition module, an energy scale module, an energy spectrum analysis module and a nuclide identification module; the data acquisition module is used to complete the collection and transmission of data. Display and real-time refresh; the energy spectrum analysis module is used to process the collected spectral line data; the energy scale module is used to convert multi-channel signals into corresponding energy to obtain energy spectrum data; The nuclide identification module is used to analyze and process energy spectrum data, complete nuclide activity calculations, distinguish between airborne source terms and deposition source terms, and calculate graphite dust deposition levels and fuel failure levels.

Further, the airborne source term and the sedimentary source term are distinguished based on the different energies of the γ energy spectrum characteristic peaks of the airborne source term and the sedimentary source term.

Further, calculating the deposition mass of graphite dust includes: based on the relationship between the activity and the mass of graphite dust in the standard sample, and converting the deposition mass of graphite dust in the pipeline through the deposition activity measurement results.

Further, calculating the fuel failure level includes:

Using the activity level of complete fuel balls measured by the burnup measurement system and the deposition activity measured online in the same cycle, calculate the dust deposition ratio of a single fuel ball and evaluate the mass loss caused by pipeline abrasion to the fuel balls;

According to the parameters of the fuel ball process manufacturing, the quality loss value that reflects the failure level is selected, and the failure level of the fuel ball is calculated based on the number of balls passed and the quality loss.

Due to the adoption of the above technical solutions, the present invention has the following characteristics:

1. The scanning rotation mechanism of the present invention is arranged outside the pipeline, and the control processing unit controls the CZT detection unit to realize scanning rotation detection along the radial and axial directions of the pipeline to complete online measurement of the pipeline radiation source items. Therefore, the present invention passes By rotating and moving the CZT detection unit, the distribution information of pipeline source items can be obtained, the pipeline source items can be measured in situ, and the source item information of the system under different working conditions can be obtained.

2. The invention is detachable and can measure source information of pipelines in different locations.

3. The front end of the CZT hemispherical detector of the present invention is provided with a shield through pin movement to avoid radiation damage to the CZT hemispherical detector caused by the high radiation dose of the fuel balls flowing in the pipeline, so as to reduce the risk of large doses. The dose rate irradiated by the CZT hemispherical detector.

In summary, the present invention can be widely used in online measurement of radiation source items in pipelines of high-temperature gas-cooled reactor fuel loading and unloading systems.

Description of the drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be considered as Limitations on the invention. Throughout the drawings, the same reference numbers refer to the same parts. In the attached picture:

Figure 1 is a schematic structural diagram of an online measurement system according to an embodiment of the present invention;

Figure 2(a) is a CZT energy spectrum model of the dust source term in the bulb of the fuel loading and unloading system according to the embodiment of the present invention;

Figure 2(b) shows the target source item simulation data according to the embodiment of the present invention;

Figure 3 shows the response of the CZT hemispheric detector to ²³² Th according to the embodiment of the present invention;

Figure 4 is a schematic structural diagram of a shielding body according to an embodiment of the present invention;

Figure 5 is a schematic diagram of the structure and pin installation of the CZT detection unit according to the embodiment of the present invention;

Figure 6 is a schematic diagram of the overall structure of the CZT detection unit and shielding body according to the embodiment of the present invention;

Figure 7 is a schematic diagram of the composition of the servo system according to the embodiment of the present invention;

Figure 8 is a schematic diagram of a measurement and analysis system according to an embodiment of the present invention.

Detailed ways

It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The terms "comprises", "includes", "contains" and "having" are inclusive and thus indicate the presence of stated features, steps, operations, elements and/or parts but do not exclude the presence or addition of one or Various other features, steps, operations, elements, components, and/or combinations thereof. The method steps, procedures, and operations described herein are not to be construed as requiring that they be performed in the particular order described or illustrated, unless an order of performance is expressly indicated. It should also be understood that additional or alternative steps may be used.

For convenience of description, spatially relative terms may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures. These relative terms, such as "inner", "outer", "inner" ”, “outside”, “below”, “above”, etc. This spatial relative relationship term Different orientations of the device in use or operation in addition to the orientation depicted in the figures are intended to be encompassed.

The design of the online measurement system for radiation source items in fuel handling system pipelines needs to consider the following factors: limited space, high background radiation interference, and many types of nuclides, including:

Limited space: In the cabin that the high-temperature reactor fuel loading and unloading system passes through, the pipelines are complex and there are many special-shaped equipment around the pipelines, resulting in a small available detection space. The radial space around the pipe is only 60cm, and this space gradually shrinks as the position of the pipe is lowered. Therefore, the miniaturization of detectors is the primary issue that needs to be considered.

High background radiation interference: An extremely radioactive fuel ball passes through the measurement pipeline. When the fuel ball passes, its instantaneous dose rate exceeds 20Gy/h. Even 5 meters away, there is a background dose rate of 0.1Gy/h. . The influence of high background can easily cause the accumulation of high-efficiency detectors, so its interference needs to be reduced.

There are many types of nuclides: the graphite dust and fuel balls deposited in the pipeline contain a variety of radioactive nuclides, and the identification and total activity quantification of the nuclides are also necessary. Therefore, the present invention requires a certain nuclide spectrum resolution.

To sum up, since there will be highly radioactive flowing materials in the pipeline, the dose rate of the pipeline deposits to be measured is about 5 orders of magnitude lower than the dose rate level of the flowing highly radioactive fuel balls. It is a major technical difficulty of the present invention to realize the detection of low-dose sediments under the interference of a high radiation environment. In addition, it is another major technical difficulty of the present invention to scan and measure the pipeline in both the axial and radial directions within a limited and narrow space, while ensuring the accuracy of the scanning.

The present invention provides an online measurement system for pipe radiation source items in a high-temperature gas-cooled reactor fuel loading and unloading system. The system includes: a CZT detection unit for detecting radioactive substances deposited in the pipe; a scanning rotation mechanism arranged outside the pipe for carrying the CZT detection unit; control processing unit, used to control the CZT detection unit to realize scanning rotation detection along the radial and axial directions of the pipeline along the scanning rotation mechanism, and complete online measurement of the pipeline radiation source item. The present invention uses a CZT detection unit to measure the radioactive material deposited in the pipeline of the high-temperature reactor fuel loading and unloading system. The present invention obtains the source item information of the system under different working conditions by measuring the source item of the pipeline in situ.

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a thorough understanding of the invention, and to fully convey the scope of the invention to those skilled in the art.

The online measurement system for pipeline radiation source items of the high-temperature gas-cooled reactor fuel loading and unloading system provided in this embodiment includes a CZT detection unit, a control unit and a data processing unit;

The scanning rotating mechanism is set outside the pipeline and is used to carry the CZT detection unit;

The control processing unit is used to control the movement of the CZT detection unit along the scanning rotation mechanism to achieve scanning rotation detection along the radial and axial directions of the pipeline, and complete online measurement of the pipeline radiation source items.

In a preferred embodiment, as shown in Figure 1, there are many nuclide characteristic peaks in the test environment and the energy of some rays is relatively high. Therefore, the CZT detection unit of this embodiment can use the CZT hemispheric detector 1 with higher energy resolution. Furthermore, considering that the dose rate of deposited graphite dust in the pipeline is about 20uSv/h and the space size requirements, this embodiment preferably uses a CZT hemispheric detector ¹ of 10*10*5mm3. The following is a simulation of the energy spectrum measurement of the CZT hemispheric detector 1. The preliminary source terms used in the simulation are shown in Table 1.

Table 1 Target nuclide source items

Using the target energy spectrum in Table 1 as the source data, according to the diameter and wall thickness of the fuel ball pipe of the HTR-PM fuel loading and unloading system, using the Monte Carlo program package Geant4, a detection model was initially established, and the CZT hemispherical shape obtained through simulation The energy spectrum response of detector 1 is shown in Figure 2. It can be seen from Figure 2 that the 10*10*5mm ³ CZT hemispheric detector can well identify the target nuclide characteristic energy peaks in Table 1. At the same time, the 10*10*5mm ³ hemispheric detector can The energy spectrum test results of ²³² Th are shown in Figure 3. The CZT hemispheric detector 1 can well identify the main characteristic peaks in ²³² Th. The main technical indicators of the CZT hemispheric detector 1 are shown in Table 2:

Table 2 Main technical indicators of CZT hemispheric detector

Furthermore, due to the complex on-site radiation environment, in order to reduce the impact of external radiation exposure on the pipeline sediment measurement results, the outside of the CZT hemispherical detector 1 can be wrapped with shielding material.

In a preferred embodiment, as shown in Figure 1, the scanning rotation mechanism includes two semicircular guide rails 2 and two linear guide rails 3. The two linear guide rails 3 are arranged in parallel and spaced apart on both sides of the fuel ball pipe 4. The semicircular guide rail 2 is arranged oppositely inside the two linear guide rails 3 to form an arc track. Each semicircular guide rail 2 is provided with a CZT hemispherical detector 1, and the CZT hemispherical detector 1 is slidably disposed on the semicircular guide rail 2 through the slider 5. Two linear guide rails 3 and two semi-circular guide rails 2, a total of four guide rails, are controlled by the control device to enable the CZT hemispheric detector 1 to achieve scanning motion along the radial and axial directions of the fuel ball pipe 4, wherein, in this embodiment The length of the entire scanning rotation mechanism is less than 1500mm, which can realize axial step measurement within the 1000mm pipe length range. The total weight of the entire measurement system is less than 50kg. Since the entire scanning rotation mechanism is fixed The fixed buckle is installed on the pipe 4. Considering the weight of the entire scanning rotation mechanism, fixed brackets 6 are introduced at both ends of the scanning rotation mechanism to transfer the weight of the entire detection device to the ground to reduce the weight of the pipeline.

Further, in order to avoid the influence of the flowing high dose rate background on the pipeline sediment measurement, a dose detection unit is provided on the slider 5 on each semicircular guide rail 2. Since the dose rate of the pipeline sediment is between 10 and Around 20uSv/h, when the dose rate detected by the dose detection unit is greater than 20uSv/h, the control processing unit controls the CZT hemispherical detector 1 to stop collecting.

Furthermore, as shown in Figures 4 to 6, a shield 7 is provided on the slider 5 of each semicircular guide rail 2 in this embodiment. The shield 7 adopts an asymmetric saddle design, and the shield 7 passes through a pin. The shaft 8 is arranged at the front end of the CZT hemispherical detector 1, and the shielding body 7 moves synchronously with the CZT hemispherical detector 1. Since the dose of the flowing fuel balls in the pipeline is very large, considering that the large dose rate may cause radiation damage to the CZT hemispherical detector 1, when the dose detection unit detects that the dose rate is greater than a set high level , the control processing unit controls the shield 7 to be rotated and placed at the front end of the CZT hemispherical detector 1 to reduce the radiation damage that may be caused to the CZT hemispherical detector 1 by the fuel balls moving in the pipeline. Therefore, by using the trigger threshold of the dose detection unit to control the acquisition of the CZT hemispherical detector 1 and the control of the shield 7, the filtering of the high background interference of the pipeline fuel balls is realized, and the CZT hemispherical detector 1 is ensured in a high-dose environment. work properly to reduce possible radiation damage.

Furthermore, in this embodiment, the mechanical control of the axial part of the pipeline can be controlled by a servo motor control system. The step progress of the servo control system is much less than 0.5mm. The radial rotation part of the pipeline is controlled by a stepper motor. . For example: In this embodiment, a 200-step stepper motor with a step angle of 1.8 degrees and a 1:20 stepper motor reducer can be selected to achieve a precision output of 0.09 degrees. The transmission ratio between the slider 5 and the arc track is 1:10. , the input accuracy is 0.9 degrees, and it is equipped with a mechanical zero return switch to improve the repeat positioning accuracy. As shown in Figure 7, the servo control system is a system that can track the input command signal and perform actions to obtain accurate position, speed and dynamics. Automatic control system for force output. There are many types of structures of servo systems, usually including controllers, power amplifiers, actuators and detection devices. The controller is the key to the servo system. Its main task is to determine the control strategy based on the input signal and feedback signal. Commonly used control algorithms include PID (proportional, integral, differential) control and optimal control. The controller can be an electronic circuit or computer. The function of the power amplifier is to amplify the signal and use it to drive the actuator to complete a certain operation. The actuator is mainly composed of a servo motor or a hydraulic servo mechanism and a mechanical transmission device. The actuator widely uses servo motors as actuators. Currently, AC servo motors or DC brushless servo motors are commonly used. The task of the detection device is to measure the controlled quantity (that is, the output quantity) to achieve feedback control. There are many types of servo systems. This embodiment uses an electrical servo system for explanation, taking this as an example and is not limited thereto. Electrical servo systems include DC servo systems, AC servo systems and stepper servo systems. According to their structural forms, they can be divided into open-loop, closed-loop and semi-closed-loop servo systems.

In a preferred embodiment, the online measurement system also includes a data processing unit. The CZT detection unit and the data processing unit can be connected through a customized cable, and the length of the customized cable can be customized according to usage requirements. The output of the data processing unit can be connected to a PC through a Gigabit network cable and the relevant nuclide identification data can be displayed on the host computer. The main technical indicators of the data processing unit are shown in Table 3:

Table 3 Main performance parameters

The data processing unit includes a user operation interface and a measurement and analysis system. The user operation interface can adopt a standard interface style. The user can realize the main functions through the operation menu or buttons. The interface can display the real-time display of collection, measurement, nuclide identification and other processes.

As shown in Figure 8, the measurement and analysis system includes a file module, a data acquisition module, an energy spectrum analysis module, and an energy spectrum analysis module. Quantity calibration module and nuclide identification module.

File module, used to open files and save spectral line data;

The data acquisition module is used to complete the collection, transmission, display and real-time refresh of spectral line data, and displays the collected spectral data and counting rate dead time and other information. It can include the acquisition setting sub-module and the acquisition control sub-module. The acquisition setting sub-module The module is used to set the acquisition timing, gamma energy detection channel selection (span and energy resolution of gamma energy detection) and mode selection (data collection interval); the acquisition control sub-module is used to start acquisition, pause acquisition, and continue Collection and termination collection settings;

The energy spectrum analysis module is used to smooth, peak search, calculate peak area and stabilize the spectrum of the collected spectral line data. Spectrum stabilization is the suppression of peak drift and is an important indicator of the portable gamma spectrometer system. Temperature changes can affect Mobility and electronic systems are the main reasons for peak drift. The IAEA-2006 standard stipulates that the operating temperature range of portable gamma spectrometers is -10°C ~ 50°C, and must have spectrum stabilization function;

The energy scale module is used to convert multi-channel spectral line data into corresponding energy to obtain energy spectrum data;

The nuclide identification module is used to analyze and process energy spectrum data and complete nuclide analysis and calculation, including nuclide library and quantitative analysis. Among them, the nuclide library is used for gamma spectrum analysis to solve the composition information of nuclide in the pipeline. Quantitative analysis is used for the analysis and calculation of nuclide. The analysis and calculation of nuclide include the calculation of nuclide activity, the distinction between airborne source term and deposition source term, and the calculation of graphite dust deposition quality and fuel failure level, among which:

1. Calculation of nuclide activity

Assume that a single-energy narrow beam of photons passes through a uniform density material with thickness There may not be any interaction with the object of action.

According to the Beer-Lambert law, before the incident parallel gamma-ray beam with energy E passes through the object, The latter intensity I ₀ (E) and I (E) satisfy the exponential decay law:
I(E)＝I ₀ (E)*e ^-μ(E)*x (1)

In the formula, μ(E) is the line attenuation coefficient of gamma rays with energy E passing through the object material, cm ^-1 . It is the total probability of various interactions of gamma photons passing through the object per unit thickness, and x is the object. Thickness, cm.

If the γ-ray acts on non-homogeneous or mixed-component materials, (1) will be rewritten as:

In the formula, n is the number of material types that γ rays pass through on the attenuation path; x _i is the thickness of different materials, and μ _i is the line attenuation coefficient of different materials.

The measurement method of the detector along the longitudinal segmentation and radial rotation makes the non-uniformly distributed nuclear deposits approximately "segmentally homogenized", which can be approximately regarded as having the same linear attenuation coefficient of the sample material in a certain segment. During the emission measurement process, since the rays emitted by the radioactive source will interact with the sample medium, the rays will attenuate and bring about the impact of self-absorption of the sample. Therefore, it is necessary to introduce a self-absorption correction factor to correct the measurement results. This method defines S( E) is the self-absorption correction factor:
S(E)＝e ^-μ(E)*d (3)

In the formula, d is the attenuation thickness of the ray in the sample.

The counts obtained by the segmented measurement are divided by the product of detection efficiency, self-absorption correction factor, γ-ray branch ratio and measurement time, and the activity Ai(E) of the radionuclide in this layer is calculated:
A _i (E)＝N(E)/(ε(E)*S(E)*p*t) (4)

In formulas (4) and (5), N(E) is the count detected by the detector; S(E) is the self-absorption correction factor; p is the branch ratio of the corresponding ray; t is a certain segmented single layer. Measurement time, s; n is the number of pipeline layers; ε(E) is detection Efficiency can be expressed as:
ε(E)＝N(E)/(A*p*t) (5)

In the formula, A is the standard scale source activity, Bq.

Divide it into n segments along the axis of the pipeline for measurement. The activity of the corresponding radionuclides in each segment in the pipeline can be obtained through equations (6) and (7):

In the formula, εij is the detection efficiency of the detector scanning to the i-th layer for radionuclides evenly distributed in the j-th layer; Ai and A are the activity of radionuclides in each layer and pipeline respectively, Bq; Ni is the detector The net count of characteristic peaks measured when scanning to the i-th layer. The left side of the multiplication sign in equation (6) is the detection efficiency matrix, which is obtained through Monte Carlo simulation software based on the condition that each segmented media material and radionuclides are uniformly distributed.

Assume that the pipeline is divided into n layers of equal height, and the detector is placed in the middle of each layer. The distance from the detector to the center of the pipeline is determined based on the condition that the detector's field of view completely covers the diameter of the pipeline. Fill the first layer of the pipeline with radioactive nuclides evenly, then move the detector sequentially from the first layer to the nth layer to conduct simulated measurements to obtain the detection efficiency under corresponding measurement conditions; then fill the second layer with radioactive nuclides evenly layer, the detector repeats the test of the first layer, and tests in this way until n layers are filled with radionuclides, thereby obtaining the efficiency matrix of the entire pipeline. When performing emission measurements, the detector is moved from the first layer to the nth layer in order to measure and obtain the corresponding counts. The activity of the nuclide in each layer can be obtained by solving the equations (6).

2. Distinguish between airborne source terms and sedimentary source terms

The airborne source term and the sedimentary source term are distinguished based on the different energies of the γ energy spectrum characteristic peaks of the airborne source term and the sedimentary source term. According to the current operating experience of HTR-PM, the main radionuclide in the airborne source item in the fuel handling system pipeline is activated Ar-41 gas, and the main γ energy spectrum characteristic peak of this nuclide is at 1293keV. As can be seen from Figure 2, the CZT measurement energy spectrum of the deposition source term has no characteristic peaks between 150-1335keV, and the characteristic peak (1293keV) of the airborne source term is significantly different. Based on this, this embodiment selects the 1293keV characteristic peak to calculate the activity of the airborne source term. Select other nuclides in the low energy section to calculate the activity of the sedimentation source term, thereby separating the airborne source term and the sedimentation source term in the pipeline, and obtaining independent source term information of the two.

3. Calculate the deposition mass of graphite dust

The measurement results of the online source term measurement system are used, combined with source term calculation, online source term measurement, pipeline sampling, fuel consumption measurement and other means to explore the graphite dust deposition law and its relationship with fuel ball failure. Specifically: through Pipeline sampling analysis, obtain the nuclide composition and activity level (specific activity) of unit mass of graphite dust, and verify each other with the source term calculation results, compare the measurement results with the prediction results based on the physical model, and compare the measurement system parameters Optimize to reduce errors and improve accuracy.

Calculate the deposition mass of graphite dust: According to the relationship between the activity and the mass of graphite dust in the standard sample, the deposition mass of graphite dust in the pipeline is converted into the deposition activity measurement results. Among them, the deposition activity measurement results: spatially integrate the measurement results of this system to obtain the cumulative γ spectrum measurement results of the dust source item with the same volume as the standard sample. Calculate the characteristic peak count of the γ spectrum and the γ spectrum characteristic peak count of the standard sample. Based on the ratio and the activity of the standard sample, the deposited activity is measured online.

4. Calculate fuel failure level

Using the activity level of the complete fuel ball measured by the burnup measurement system in the same cycle and the deposition activity measured online, the dust deposition ratio of a single fuel ball is calculated and the mass loss caused by pipeline abrasion to the fuel ball is evaluated. Specifically: According to the obtained graphite dust deposition quality in the pipeline and the number of balls passing during the operation period, the conversion Find the average dust deposition mass of each fuel ball, divide this mass by the mass of the complete fuel ball, and get the mass loss; calculate the fuel failure level, specifically: according to the parameters of the fuel ball process manufacturing, select the mass loss value of the reaction failure level, according to The number of ball passes and mass loss are used to calculate the failure level of the fuel ball.

Each embodiment in this specification is described in a progressive manner. The same and similar parts between the various embodiments can be referred to each other. Each embodiment focuses on its differences from other embodiments. In the description of this specification, reference to the description of "one embodiment," "some implementations," etc. means that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one implementation of the embodiment of the specification. example or examples. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described in this specification unless they are inconsistent with each other.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be used Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent substitutions are made to some of the technical features; however, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

An online measurement system for radiation source items in pipelines of high-temperature gas-cooled reactor fuel loading and unloading systems, which is characterized in that the system includes:

CZT detection unit, used to detect radioactive materials deposited in pipelines;

A scanning rotation mechanism is provided outside the pipeline and used to carry the CZT detection unit;

A control processing unit is used to control the CZT detection unit to implement scanning rotation detection along the radial and axial directions of the pipeline along the scanning rotation mechanism to complete online measurement of the pipeline radiation source item.
The online measurement system for pipeline radiation source items of a high-temperature gas-cooled reactor fuel loading and unloading system according to claim 1, characterized in that the CZT detection unit adopts a CZT hemispherical detector.
The online measurement system for pipeline radiation source items of a high-temperature gas-cooled reactor fuel loading and unloading system according to claim 2, wherein the scanning rotation mechanism includes two semicircular guide rails and two linear guide rails, and the two linear guide rails The two semi-circular guide rails are arranged at parallel intervals along the axial direction of the pipeline; the two semi-circular guide rails are arranged oppositely to form arc-shaped rails inside the two linear guide rails, and can move linearly along the straight rails; each of the semi-circular guide rails has The CZT hemispherical detector is set by sliding the slider, and the control processing unit controls the movement of the CZT hemispherical detector along the linear guide rail and arc track to achieve scanning and rotation detection along the radial and axial directions of the pipeline.
The online measurement system for pipeline radiation source items of a high-temperature gas-cooled reactor fuel loading and unloading system according to claim 3, characterized in that a dose detection unit is also provided on the slider of each semicircular guide rail, and the control processing unit The data detected by the dose detection unit is obtained. When the dose rate detected by the dose detection unit is greater than the set value, the control processing unit controls the CZT hemispherical detector to stop collecting.
The high-temperature gas-cooled reactor fuel loading and unloading system pipeline radiation source item online measurement system according to claim 4, characterized in that a shielding body is also provided on the slider of each semicircular guide rail, and the shielding body passes through a pin The axis is set at the front end of the CZT hemispheric detector. When the dose detection unit detects that the dose exceeds the standard, the control processing unit controls the shield to rotate and place it at the front end of the CZT hemispheric detector to reduce the The CZT hemispherical detector receives ray irradiation.
The online measurement system for pipeline radiation source items in the high-temperature gas-cooled reactor fuel loading and unloading system according to any one of claims 1 to 5, characterized in that the online measurement system further includes a data processing unit for detecting the CZT detection unit The results are analyzed and processed.
The online measurement system for pipeline radiation source items of a high-temperature gas-cooled reactor fuel loading and unloading system according to claim 6, wherein the data processing unit includes a measurement analysis system; the measurement analysis system includes a data acquisition module, an energy scale module, The energy spectrum analysis module and the nuclide identification module; the data acquisition module is used to complete the collection, transmission, display and real-time refreshing of data; the energy spectrum analysis module is used to process the collected spectral line data; the energy scale The module is used to convert multi-channel signals into corresponding energy to obtain energy spectrum data; the nuclide identification module is used to analyze and process the energy spectrum data to complete nuclide activity calculations and airborne source terms. Distinguish between deposition source terms and calculate graphite dust deposition levels and fuel failure levels.
The high-temperature gas-cooled reactor fuel loading and unloading system pipeline radiation source item online measurement system according to claim 7, characterized in that the energy of the γ energy spectrum characteristic peaks of the airborne source item and the deposition source item is different according to the energy of the airborne source item. Distinguish with the sedimentary source term.
The online measurement system for pipe radiation source items of a high-temperature gas-cooled reactor fuel loading and unloading system according to claim 7, characterized in that calculating the deposition quality of graphite dust includes: according to the mass relationship between the activity and graphite dust in the standard sample, through deposition The activity measurement results are converted into the deposition mass of graphite dust in the pipeline.
The high-temperature gas-cooled reactor fuel loading and unloading system pipeline radiation source item online measurement system according to any one of claims 7 to 9, characterized in that calculating the fuel failure level includes:

Using the activity level of intact fuel balls measured by the burnup measurement system during the same cycle, measured online Deposition activity, calculates the dust deposition ratio of a single fuel ball, and evaluates the mass loss caused by pipeline abrasion to the fuel ball;

According to the parameters of the fuel ball process manufacturing, the quality loss value that reflects the failure level is selected, and the failure level of the fuel ball is calculated based on the number of balls passed and the quality loss.