Device and method for detecting hydrogen content of zirconium alloy structural member in reactor

Abstract

The invention belongs to the technical field of nuclear-grade zirconium alloy in-service detection, and particularly relates to a device and a method for detecting the hydrogen content of a zirconium alloy structural member in a reactor. Comprising a laser light source module, a sample platform, a spectrum acquisition module and a data storage processing module, the laser light source module is connected with the spectrum acquisition module and outputs signals to the spectrum acquisition module, the spectrum acquisition module is connected with the data storage processing module and outputs data to the data storage processing module, and the laser light source module irradiates a sample on the sample platform. And the spectrum acquisition module is used for detecting the sample on the sample platform. The device and the method have the beneficial effects that in-situ detection of the hydrogen content of the reactor core-grade zirconium alloy structural member can be realized by utilizing the device and the method provided by the invention, the problems of long time consumption and high cost caused by transfer of a radioactive sample and the like in a traditional mechanical method are avoided, and the device and the method are suitable for industrial production. And mechanical tool operation does not need to be carried out by relying on a loading and unloading machine, and design simplification is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of in-service detection of nuclear-grade zirconium alloys, and in particular relates to a device and method for detecting hydrogen content in a zirconium alloy structural part in a reactor. Background Art

[0002] Nuclear-grade zirconium alloys are used for the manufacture of reactor core structural parts such as heavy water reactor pressure tubes, research reactor irradiation test loops, and isotope production channels due to their high strength, corrosion resistance, and low neutron absorption cross-section. During long-term service, due to the corrosion of the reactor coolant, the hydrogen element in the reactor coolant will diffuse into the zirconium alloy, causing the hydrogen content in the zirconium alloy to continue to increase, and eventually generate brittle Zr-H intermetallic compounds in the zirconium alloy matrix, causing hydrogen-induced delayed cracking and other phenomena, endangering the safety of zirconium alloy structural parts and reactors.

[0003] In order to prevent the hydrogen content in zirconium alloy from exceeding the allowable limit during service, it is necessary to continuously monitor the change of hydrogen content in zirconium alloy during service, which requires extracting samples from zirconium alloy and then analyzing the chemical composition of the samples. At present, the method of extracting hydrogen content test samples is mainly mechanical method. For example, the nuclear-grade zirconium alloy used for the pressure tube in the fuel channel of heavy water reactor has a design service life of 25 to 30 years.

[0004] Methods for monitoring hydrogen content in this alloy fall into two categories:

[0005] 1) Remove the entire pressure tube (i.e., “extubate”), then cut a block sample from the pressure tube that can be used for hydrogen content analysis, and then install a new pressure tube at the same location;

[0006] 2) Empty the pressure tube (during operation, the pressure tube contains multiple fuel rod bundles and reactor coolant), and then use special tools to probe into the inner side of the pressure tube (the side in contact with the reactor coolant) from the reactor end face, and scrape about 60μm thick chip samples from the inner wall of the pressure tube twice to analyze the hydrogen content in the samples.

[0007] The limitations of existing methods include two aspects:

[0008] 1) When the above two methods are used in heavy water reactors, they both need to be completed with the help of special tools operated by the loading and unloading machine located at the end of the reactor. When conducting chemical composition analysis, the sample must be transferred to a special hot chamber for testing, which involves sample cooling and transportation, and the test cycle is long. There are also certain requirements for the test conditions of the hot chamber. In addition, the first method also involves the removal of the entire pressure tube and the installation of a new pressure tube. Since the replaced pressure tube has a higher radioactivity as a whole, it is more difficult to implement and more costly.

[0009] 2) Due to the requirement of high reliability, it is also necessary to conduct regular in-service testing of the hydrogen content in the nuclear-grade zirconium alloy structural parts used in the isotope production channels. However, due to the structural characteristics of heavy water reactors, it is difficult to take samples using similar mechanical methods. In addition, the transportation and cooling cycles of radioactive samples are long, which affects the normal operation of the reactor. Therefore, the traditional hydrogen content detection method for zirconium alloy structural parts suitable for heavy water reactors cannot meet the operation and maintenance requirements of heavy water reactors. Summary of the invention

[0010] The purpose of the present invention is to provide a device and method for detecting the hydrogen content of zirconium alloy structural parts in a reactor, and the technical problem to be solved is to measure the hydrogen content of zirconium alloy structural parts in a reactor without damaging the sample, so as to realize in-situ, rapid and non-destructive detection of the hydrogen content of zirconium alloy structural parts in the reactor.

[0011] The technical solution of the present invention is as follows: a device for detecting the hydrogen content of a zirconium alloy structural part in a reactor, comprising a laser light source module, a sample platform, a spectrum acquisition module and a data storage and processing module, wherein the laser light source module is connected to the spectrum acquisition module and outputs signals to the spectrum acquisition module, the spectrum acquisition module is connected to the data storage and processing module and outputs data to the data storage and processing module, the laser light source module irradiates the sample on the sample platform, and the spectrum acquisition module detects the sample on the sample platform.

[0012] The laser light source module comprises a laser, a reflector and a convex lens. The laser emitted by the laser is reflected by the reflector and then irradiated to the sample on the sample platform through the convex lens.

[0013] The spectrum acquisition module includes a probe, a digital delay generator and a spectrometer. The probe detects the laser reflected by the sample on the sample platform and inputs the signal to the spectrometer. The digital delay generator is connected to the spectrometer and the laser respectively. The spectrometer outputs the processed signal to the data storage and processing module.

[0014] The data storage and processing module is a computer.

[0015] A method for detecting hydrogen content in a zirconium alloy structural part in a reactor comprises the following steps:

[0016] Step 1: Obtain information on hydrogen content in zirconium alloy;

[0017] Step 2: Create an argon environment and a variable temperature environment;

[0018] Step 3: Model construction;

[0019] Step 4: Spectral intensity correction.

[0020] The step 1 is to obtain a spectral signal by selecting appropriate laser energy, light collection angle and spectrometer delay time, and obtain the hydrogen content information in the zirconium alloy according to the obtained spectral signal.

[0021] The step 2 is to tilt two air pipes at 45 degrees above the sample and spray argon to create an argon environment; use a copper heating table to heat the zirconium alloy sample, and use an infrared camera to measure the temperature to determine the sample temperature.

[0022] The step 3 is to use LIBS to test zirconium alloy samples under different conditions to obtain spectral data containing composition information of zirconium alloy, select 5 test points for each sample for testing, then take the average value of the results of the LIBS spectral data of the 5 test points, pre-process the spectral data, remove the interference of the background spectrum, and perform normalization.

[0023] The step 4 is to realize the detection of hydrogen content at non-calibrated temperature by finding the correction coefficient, and the calculation formula is t / kt0, t0 is 25°C, t is the actual temperature during measurement, and k is the temperature correction coefficient when the temperature is t.

[0024] The beneficial effects of the present invention are as follows: the device and method provided by the present invention can realize in-situ detection of the hydrogen content of the reactor core-level zirconium alloy structural parts, avoiding the time-consuming and high-cost problems caused by the transportation of radioactive samples in traditional mechanical methods, and there is no need to use mechanical tools relying on loading and unloading machines, which is conducive to achieving design simplification. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural diagram of a device for detecting hydrogen content in a zirconium alloy structural part in a reactor provided by the present invention;

[0026] Figure 2 This is a schematic diagram of the intensity of the hydrogen element spectrum in an argon environment;

[0027] Figure 3 This is the full spectrum of zirconium alloy samples at different temperatures;

[0028] Figure 4 Temperature calibration curve for LIBS (laser induced breakdown spectroscopy) detection of hydrogen in zirconium alloy.

[0029] In the figure: 1 laser, 2 reflector, 3 convex lens, 4 sample platform, 5 probe, 6 digital delay generator, 7 spectrometer, 8 computer. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1As shown, a device for detecting hydrogen content in a zirconium alloy structural part in a reactor includes a laser light source module, a sample platform 4, a spectrum acquisition module and a data storage processing module, wherein the laser light source module is connected to the spectrum acquisition module and outputs signals to it, the spectrum acquisition module is connected to the data storage processing module and outputs data to it, the laser light source module irradiates the sample on the sample platform 4, and the spectrum acquisition module detects the sample on the sample platform 4.

[0032] The laser light source module comprises a laser 1 , a reflector 2 and a convex lens 3 . The laser light emitted by the laser 1 is emitted by the reflector 2 and then irradiated to the sample on the sample platform 4 by the convex lens 3 .

[0033] The spectrum acquisition module includes a probe 5, a digital delay generator 6 and a spectrometer 7. The probe 5 detects the laser reflected by the sample on the sample platform 4 and inputs the signal to the spectrometer 7. The digital delay generator 6 is connected to the spectrometer 7 and the laser 1 respectively. The spectrometer 7 outputs the processed signal to the data storage and processing module.

[0034] In the present invention, the computer 8 is selected to be used as the data storage and processing module.

[0035] Laser 1 is mainly responsible for generating laser pulses. After emitting high-energy laser, it is reflected by reflector 2 and focused by convex lens 3 onto the sample surface in sample platform 4. After the high-energy laser acts on the sample, the electrons in excited atoms and molecules transition to lower energy levels to form a linear spectrum, which is collected by a spectrum acquisition module composed of probe 5, digital delay generator 6 and spectrometer 7 and saved in computer 8.

[0036] The device of the present invention can obtain a spectral signal with high signal-to-noise ratio and signal-to-background ratio under appropriate laser energy, light collection angle and spectrometer delay time, and has the following usage:

[0037] LIBS detection method based on argon gas spraying

[0038] By controlling the gas environment of the sample test bench by spraying argon gas through a gas pipe, the intensity of the spectral line of the element to be detected can be improved. The zirconium alloy standard sample is tested using LIBS in an argon environment to obtain spectral data containing the zirconium alloy composition information. The spectral data is preprocessed to remove the interference of the background spectrum and normalized to obtain spectral lines containing hydrogen element content information.

[0039] Sample measurements at different ambient temperatures

[0040] LIBS tests were carried out under the same instrument parameters and at different temperatures. The spectral data were preprocessed to remove the interference of the background spectrum and normalized. The spectral data obtained at different ambient temperatures were analyzed to obtain the temperature curves of hydrogen and zirconium elements.

[0041] Temperature calibration curve

[0042] The fitting method is used to obtain the temperature correction curve for hydrogen content detection, and a temperature correction model is established to enhance the applicability of the detection method and improve the accuracy of hydrogen element detection in zirconium alloys.

[0043] A method for detecting hydrogen content in a zirconium alloy structural part in a reactor comprises the following steps:

[0044] Step 1: Obtain information on hydrogen content in zirconium alloy

[0045] By selecting appropriate laser energy, light collection angle and spectrometer delay time, a spectral signal with high signal-to-noise ratio and signal-to-background ratio is obtained, and the hydrogen content information in the zirconium alloy is obtained based on the obtained spectral signal.

[0046] Step 2: Create an argon environment and a variable temperature environment

[0047] The two air pipes are tilted at 45° above the sample. The air pipe nozzles are placed as close to the sample surface as possible without interfering with the vertically incident laser pulse and affecting the light collection of the spectrometer to create an argon environment. The zirconium alloy sample is heated using a copper heating table and measured using an infrared camera to determine the sample temperature.

[0048] Step 3: Model building

[0049] LIBS was used to test zirconium alloy samples under different conditions to obtain spectral data containing the composition information of zirconium alloy. Five test points were selected for each sample, and then the results of the LIBS spectral data of these five test points were averaged to reduce the influence of accidental errors. The spectral data was preprocessed to remove the interference of the background spectrum and normalized.

[0050] Step 4: Spectral Intensity Correction

[0051] Temperature changes during detection will affect the LIBS test results. By looking up the correction coefficient, the hydrogen content detection at non-calibrated temperature can be achieved. The calculation formula is t / kt0, t0 is 25℃, t is the actual temperature during measurement, and k is the temperature correction coefficient when the temperature is t.

Claims

1. A device for detecting hydrogen content in zirconium alloy structural parts in a reactor, characterized in that: It includes a laser light source module, a sample platform, a spectrum acquisition module and a data storage processing module. The laser light source module is connected to the spectrum acquisition module and outputs signals to it, the spectrum acquisition module is connected to the data storage processing module and outputs data to it, the laser light source module irradiates the sample on the sample platform, and the spectrum acquisition module detects the sample on the sample platform.

2. A device for detecting hydrogen content in a zirconium alloy structural component in a reactor as claimed in claim 1, characterized in that: The laser light source module comprises a laser, a reflector and a convex lens. The laser emitted by the laser is reflected by the reflector and then irradiated to the sample on the sample platform through the convex lens.

3. A device for detecting hydrogen content in a zirconium alloy structural component in a reactor as claimed in claim 1, characterized in that: The spectrum acquisition module includes a probe, a digital delay generator and a spectrometer. The probe detects the laser reflected by the sample on the sample platform and inputs the signal to the spectrometer. The digital delay generator is connected to the spectrometer and the laser respectively. The spectrometer outputs the processed signal to the data storage and processing module.

4. A device for detecting hydrogen content in a zirconium alloy structural component in a reactor as claimed in claim 1, characterized in that: The data storage and processing module is a computer.

5. A method for detecting hydrogen content in zirconium alloy structural parts in a reactor, characterized in that: The steps include: Step 1: Obtain information on hydrogen content in zirconium alloy; Step 2: Create an argon environment and a variable temperature environment; Step 3: Model building; Step 4: Spectral intensity correction.

6. A method for detecting hydrogen content in a zirconium alloy structural component in a reactor as claimed in claim 5, characterized in that: The step 1 is to obtain a spectral signal by selecting appropriate laser energy, light collection angle and spectrometer delay time, and obtain the hydrogen content information in the zirconium alloy according to the obtained spectral signal.

7. A method for detecting hydrogen content in a zirconium alloy structural component in a reactor as claimed in claim 5, characterized in that: The step 2 is to tilt two air pipes at 45 degrees above the sample and spray argon to create an argon environment; use a copper heating table to heat the zirconium alloy sample, and use an infrared camera to measure the temperature to determine the sample temperature.

8. A method for detecting hydrogen content in a zirconium alloy structural component in a reactor as claimed in claim 5, characterized in that: The step 3 is to use LIBS to test zirconium alloy samples under different conditions to obtain spectral data containing composition information of zirconium alloy, select 5 test points for each sample for testing, then take the average value of the results of the LIBS spectral data of the 5 test points, pre-process the spectral data, remove the interference of the background spectrum, and perform normalization.

9. A method for detecting hydrogen content in a zirconium alloy structural component in a reactor as claimed in claim 5, characterized in that: The step 4 is to realize the detection of hydrogen content at non-calibrated temperature by finding the correction coefficient, and the calculation formula is t / kt0, t0 is 25°C, t is the actual temperature during measurement, and k is the temperature correction coefficient when the temperature is t.

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