Method for testing corrosion of nuclear reactor chemical shutdown poison to main equipment material

Abstract

The invention discloses a method for testing corrosion of a nuclear reactor chemical shutdown poison to a main equipment material. The method comprises the steps of sample pretreatment, test parameter design, cross corrosion test, sample aftertreatment and thermal test. The test pretreatment comprises the steps of grinding, polishing, cleaning, drying and weighing a main equipment material sample; the test parameter design comprises design of types, concentrations and shut-down conditions of chemical shut-down toxicants, and different types of chemical shut-down toxicants can establish a comparison relationship by means of an equivalent thermal neutron absorption cross section; the sample post-treatment comprises the steps of washing, drying, weighing and necessary characterization of the corroded main equipment material sample; the cross corrosion test comprises a long-period static corrosion test and an electrochemical test; the thermotechnical test comprises a critical heat flux density test. Aiming at the selection limitation of the existing single type of chemical shutdown poison, the corrosion influence of chemical shutdown on the nuclear reactor is reduced, an effective test analysis method is provided for research and development of the high-efficiency low-corrosion chemical shutdown poison, and multi-purpose reactor core evaluation can be flexibly analyzed.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear reactor primary circuit material safety, and specifically provides a test method for corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor. Background Art

[0002] The chemical shutdown system is an important backup shutdown system for nuclear reactors to ensure the diversity of shutdown methods for nuclear reactors. The function of the chemical shutdown is to immediately inject high-concentration neutron poisons into the reactor when the reactor control rods are stuck and cannot be inserted due to possible reasons, so that the reactor reaches a certain negative reactivity depth and achieves a subcritical shutdown of the nuclear reactor, that is, a safe shutdown.

[0003] At present, boric acid is the most commonly used neutron poison for chemical shutdown of pressurized water reactor nuclear power plants. The main reason is that boric acid has low cost and is easy to post-process. Considering that the neutron cross section of boric acid is lower than that of cadmium nitrate and gadolinium nitrate, the injected boric acid concentration is required to be high, and the final reserve of chemical shutdown poison has a large volume and exhibits high acidity. The optimal primary loop pH value of a nuclear reactor is alkaline. The acidity of high-concentration boric acid will cause a certain test to the surface state of the main equipment in the core. Analyzing the effects of different neutron poisons is beneficial for multi-purpose nuclear reactors to adapt to different working requirements.

[0004] Restarting a nuclear reactor after a chemical shutdown requires a re-evaluation of the safety of the main equipment of the nuclear reactor, such as the state of the surface oxide film and thermal parameters. Timely and sufficient corrosion testing and evaluation of the main equipment materials is an important means to ensure safety inside the reactor. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a test method for the corrosion of nuclear reactor chemical shutdown poisons on main equipment materials. The present invention aims at the selection limitations of the existing single type of chemical shutdown poisons, considers the corrosion effect of chemical shutdown on nuclear reactors, and provides an effective test analysis method for the research and development of high-efficiency and low-corrosive chemical shutdown poisons, and can flexibly analyze core evaluation for multiple purposes.

[0006] In order to achieve the above object, the present invention adopts the following technical solution

[0007] A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor, characterized in that it comprises the following steps:

[0008] Step 1: Sample pretreatment, including grinding, polishing, cleaning, drying and weighing the main equipment material sample;

[0009] Step 2: Experimental parameter design: including designing the type, concentration and shutdown conditions of chemical shutdown poisons, where different types of chemical shutdown poisons are compared based on equivalent thermal neutron absorption cross sections;

[0010] Step 3: Cross corrosion test: including long-term static corrosion test and electrochemical test;

[0011] Step 4: Sample post-processing: including rinsing, drying, weighing and necessary characterization of the main equipment material samples after corrosion;

[0012] Step 5: Thermal test: including critical heat flux density test, convection heat transfer coefficient measurement and flow resistance coefficient measurement.

[0013] The present invention aims at the selection limitation of the existing single type of chemical shutdown poison, considers the corrosion effect of chemical shutdown on nuclear reactors, provides an effective experimental analysis method for the research and development of high-efficiency and low-corrosive chemical shutdown poisons, and can flexibly analyze core evaluation for multiple purposes.

[0014] Furthermore, the main equipment material sample material includes but is not limited to zirconium alloy, austenitic stainless steel and Inconel alloy.

[0015] Furthermore, the material size of the main equipment material sample needs to meet the specified size, such as 40*20*2mm for long-period static corrosion test and 10*10*2mm for electrochemical test.

[0016] Furthermore, one side of the electrochemical test main equipment material sample is exposed for measurement, and the other side should be connected to an external wire and avoid participating in the reaction. Optional methods to avoid the reaction include encapsulation with epoxy resin, or clamping with a flat plate to avoid the working liquid.

[0017] Furthermore, the grinding should be done through multiple grinding processes, such as 400#, 800#, 1200#, 4000#, and each grinding should be perpendicular to the last grinding scratch.

[0018] Furthermore, the polishing should be carried out through multiple polishing processes, such as 3μm, 1μm, 0.5μm, and silica polishing liquid polishing, until the surface is clean and scratch-free, and the surface roughness should be less than 0.8μm measured by LSCM, meeting the NB / T 20538-2018 standard for zirconium alloy pipes for fuel cladding of pressurized water reactor nuclear power plants.

[0019] Furthermore, the cleaning is carried out with deionized water and alcohol or acetone in sequence, and ultrasonic cleaning is performed for two minutes.

[0020] Furthermore, the drying method is drying in an oven or drying with a hair dryer to ensure that there is no water stain on the surface.

[0021] Furthermore, the types of chemical shutdown poisons include boric acid, cadmium nitrate or gadolinium nitrate. The solution concentration includes the concentration required for various types of rod stuck accident conditions and their concentrated concentrations. The shutdown conditions include hot shutdown, cold shutdown and the transition between the two conditions.

[0022] Furthermore, the shutdown condition coolant temperature can be selected from 50°C to 280°C.

[0023] Furthermore, the weighing in the pre-test treatment (1), i.e. the first weighing, is counted as W 1 The weighing in the post-test treatment (4), i.e. the second weighing after corrosion, is calculated as W 2 , the corrosion test time is h, using the formula (W 1 -W 2 ) / h as the static corrosion rate.

[0024] Furthermore, the long-period static corrosion test is carried out by hanging the main equipment material samples in a hydrothermal reactor. If the shutdown condition is low temperature and low pressure, it can be carried out by hydrothermal cycle heating.

[0025] Furthermore, the electrochemical test is to measure the main equipment material sample by an electrochemical workstation through a constant temperature water bath, and the electrochemical measurement is carried out through a three-electrode system, using a Pt counter electrode, a saturated calomel reference electrode, and the main equipment material sample as working electrodes.

[0026] Furthermore, the electrochemical test includes measuring open circuit potential, constant potential polarization under open circuit potential, electrochemical impedance spectroscopy and equivalent circuit simulation.

[0027] Furthermore, the characterization includes LSCM, SEM, XRD and XPS.

[0028] Furthermore, the thermal engineering test includes a critical heat flux test, which can be selected as a pool boiling critical heat flux test, or a critical heat flux test under swinging conditions to meet the needs of ocean power or floating nuclear reactors; the convective heat transfer coefficient measurement includes forced convection heat transfer coefficient measurement and natural convection heat transfer coefficient measurement; the flow resistance coefficient measurement includes circular tube flow channel resistance coefficient, sudden change pipeline resistance coefficient, and sudden contraction pipeline resistance coefficient.

[0029] Furthermore, the critical heat flux test measures the change in critical heat flux before and after the corrosion test of the main equipment material. The critical heat flux is related to the surface roughness and cannot be directly derived through theory. The critical heat flux may be reduced due to the compactness of pitting pits and corrosion oxide film. In this case, it is necessary to further determine whether the nuclear fuel cladding meets the requirements of the thermal design criteria. If it is lower than the thermal design criteria, the reactor is not allowed to be restarted. The critical heat flux may increase due to the roughening of the main equipment material sample after corrosion. From the thermal engineering perspective of the nuclear reactor, the increase in critical heat flux is beneficial to the safety inside the reactor.

[0030] Furthermore, the convective heat transfer coefficient is measured, and the improvement of the convective heat transfer coefficient is beneficial to increasing the heat transfer efficiency of the nuclear reactor and improving the economy of the reactor.

[0031] Furthermore, in the flow resistance measurement, the oxide film morphology of the main equipment material before and after corrosion test may affect the flow in the pipeline, and an increase in the resistance coefficient will be detrimental to the pipeline flow and reduce the heat exchange.

[0032] Furthermore, the different types of chemical shutdown poisons can be compared by using equivalent thermal neutron absorption cross sections. The equivalent thermal neutron absorption cross sections are based on the enrichment of the natural isotopes of the chemical shutdown poisons. Concentrated nuclides are preferably applicable to chemical shutdown poisons. Concentrated nuclides have higher equivalent thermal neutron absorption cross sections. For example, natural boric acid (B 10 enrichment of 19.9%) with a thermal neutron equivalent absorption cross section of 764 and enriched boric acid (B 10 The enrichment is 20%) and the thermal neutron equivalent absorption cross section is 1152.

[0033] The characterization includes LSCM measurement of the surface roughness of the main equipment material sample, SEM measurement of the morphology before and after corrosion and the thickness of the oxide film after corrosion, XRD measurement of the crystal structure and state after corrosion, and XPS measurement of the chemical composition and chemical state after corrosion.

[0034] The LSCM measurement area is 350.88×264.19 μm, and the arithmetic mean roughness and three-dimensional view of the main equipment material sample before and after corrosion are measured in a random manner.

[0035] The SEM compares and observes the appearance before and after corrosion, and distinguishes the corrosion products of different properties in the surface oxide film. The main equipment material sample can be cut into any thickness under different corrosion conditions to obtain the middle cross section. The SEM observation of the middle cross section can measure the thickness of the corrosion oxide film under different corrosion conditions. Furthermore, the corrosion products of different properties can be scraped and ground for XRD characterization. The XRD characterization results show the diffraction peaks of different elemental components, that is, the product components.

[0036] The XPS can perform energy spectrum analysis on the surface of the main equipment material sample before and after corrosion to obtain the content of main elements on the surface, and can also verify the characteristic peaks of the components obtained in XRD.

[0037] The different types of chemical shutdown poisons can be compared based on equivalent thermal neutron absorption cross sections. Since the equivalent thermal neutron absorption cross sections of different types of chemical shutdown poisons are different, it is stipulated that different types of chemical shutdown poisons achieve the same neutron absorption capacity, that is, under the premise that different types of chemical shutdown solutions have the same shutdown capacity but different concentrations, a comparative corrosion evaluation of different types of chemical shutdown poisons is performed.

[0038] Furthermore, the different types of chemical shutdown poisons can be compared by equivalent thermal neutron absorption cross sections. First, the static corrosion rates of different types of chemical shutdown poisons are compared. The larger the static corrosion rate, the stronger the static corrosion of the chemical shutdown poison. Secondly, the thickness and density of the oxide film are characterized by SEM. Different chemical shutdown poisons have different corrosion mechanisms. The formation and function of the oxide film can be evaluated by linking the static corrosion rate of the previous item. XRD and XPS characterize and analyze the composition and valence changes of zirconium alloys in different types of chemical shutdown poisons, so as to determine the influence of the composition on corrosion in a targeted manner.

[0039] Furthermore, the different types of chemical shutdown poisons can be compared by relying on equivalent thermal neutron absorption cross sections. The higher the open circuit potential of different types of chemical shutdown poisons, the weaker the corrosion tendency of the poisons. Polarization curves can describe the trend of the passivation zone of different types of chemical shutdown poisons changing with concentration. Different types of chemical shutdown poisons are simulated by the same equivalent impedance spectrum, which can quantitatively compare the contact resistance, charge transfer resistance and constant phase angle of the electrochemical reaction solution.

[0040] Furthermore, when the cross corrosion test is carried out, the oxygen concentration is lower than 200 ppb. Oxygen will accelerate metal corrosion. When the dissolved oxygen is lower than 200 ppb, the effect of dissolved oxygen on corrosion can be approximately ignored. It is believed that the main environmental factor for the corrosion of the main equipment material sample is the solution itself, avoiding oxygen interference.

[0041] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0042] 1. Different chemical shutdown poisons can be compared in terms of corrosion capacity based on the same thermal neutron equivalent absorption cross section, that is, the concentrations of various chemical shutdown solutions are different, but their shutdown capacity is the same;

[0043] 2. The present invention is aimed at chemical shutdown conditions, and the test conditions meet the actual low temperature and low pressure conditions of nuclear reactors, and the test cost is low;

[0044] 3. The sample pretreatment of the present invention ensures that the main equipment material samples meet the requirements of typical pressurized water reactor nuclear fuel cladding, meet the actual needs of nuclear power plants, and at the same time ensure that the corrosion test data tends to be conservative;

[0045] 4. The present invention improves the measurement of the corrosion capacity of chemical shutdown poisons, and can qualitatively analyze the composition and content of corrosion products by characterization; at the same time, the corrosion tendency of chemical shutdown solutions of different concentrations is tested by electrochemical tests, and the influence of corrosion products on metals is further analyzed;

[0046] 5. The present invention conducts thermal tests on corroded main equipment material samples, providing data support for the safety of nuclear reactor restart. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of a test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor.

[0048] Figure 2 It is a schematic diagram of a specific embodiment for a pressurized water reactor nuclear power plant. Figure 3 A simplified corrosion mechanism simulation was established using sample post-treatment. DETAILED DESCRIPTION

[0049] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings of the examples of the present invention. 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 creative work are within the scope of protection of the present invention.

[0050] like Figure 1 As shown, a test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor of the present invention comprises the following steps:

[0051] Step 1: Sample pretreatment, including grinding, polishing, cleaning, drying and weighing the main equipment material sample;

[0052] Step 2: Experimental parameter design: including designing the type, concentration and shutdown conditions of chemical shutdown poisons, where different types of chemical shutdown poisons are compared based on equivalent thermal neutron absorption cross sections;

[0053] Step 3: Cross corrosion test: including long-term static corrosion test and electrochemical test;

[0054] Step 4: Sample post-processing: including rinsing, drying, weighing and necessary characterization of the main equipment material samples after corrosion;

[0055] Step 5: Thermal test: including critical heat flux density test, convection heat transfer coefficient measurement and flow resistance coefficient measurement.

[0056] Example

[0057] The concentration of chemical shutdown poison in the present invention is based on the existing third-generation pressurized water reactor nuclear power plant, the temperature is considered to be the transition from hot shutdown to cold shutdown, and the time is considered to be an interval of ten days. Further comprehensive long-term static corrosion test and electrochemical test are used to obtain a preliminary judgment, and then the nuclear reactor targeted thermal test is carried out on the main equipment material samples after corrosion, such as Figure 2 As shown, this example is described in detail below.

[0058] The main equipment material sample material is considered to be the nuclear fuel cladding of a pressurized water reactor nuclear power plant, and zirconium 4 alloy is selected.

[0059] The sample material size of the main equipment material can be selected as 40*20*2mm for long-period static corrosion test and 10*10*2mm for electrochemical test.

[0060] The material sample of the electrochemical test main equipment is exposed on one side for measurement, and the other side should be connected to an external wire and encapsulated with epoxy resin.

[0061] The grinding is performed through multiple grinding processes, such as 400#, 800#, 1200#, 4000#, and each grinding should be perpendicular to the last grinding scratch.

[0062] The polishing is carried out through multiple polishing processes, such as 3μm, 1μm, 0.5μm, and silica polishing liquid polishing, until the surface is clean and scratch-free, and the surface roughness is less than 0.8μm measured by LSCM, which meets the NB / T20538-2018 standard for zirconium alloy pipes for fuel cladding of pressurized water reactor nuclear power plants.

[0063] The cleaning is carried out with deionized water and alcohol in sequence, and ultrasonic cleaning is performed for two minutes.

[0064] The drying method is oven hanging drying to ensure that there is no obvious water stain on the surface.

[0065] The chemical shutdown poison is natural boric acid. The solution concentration is selected in three gradients: 270ppm, 650ppm and 1300ppm, corresponding to the severity of three types of nuclear power plant rod jam accidents, the most valuable two-bundle control rod failure, the most valuable five-bundle control rod failure and all control rod failure.

[0066] The coolant temperature for the shutdown condition is selected to be 100°C for cold shutdown.

[0067] The first weighing is W 1 The second weighing after corrosion is W 2 , the corrosion test time is h, using the formula (W 1 -W 2) / h as the static corrosion rate.

[0068] The long-period static corrosion test is carried out by hanging the main equipment material sample in a hydrothermal reactor.

[0069] The electrochemical test is to measure the main equipment material sample by an electrochemical workstation through a constant temperature circulating water bath. The electrochemical measurement is carried out through a three-electrode system, using a Pt counter electrode, a saturated calomel reference electrode, and the sample as a working electrode.

[0070] The electrochemical test includes measuring open circuit potential, constant potential polarization under open circuit potential, electrochemical impedance spectroscopy and equivalent circuit simulation.

[0071] The characterization includes LSCM measurement of the surface roughness of the main equipment material sample, SEM measurement of the morphology of the main equipment material sample before and after corrosion and the thickness of the oxide film of the main equipment material sample after corrosion, XRD measurement of the crystal structure and state of the main equipment material sample after corrosion, and XPS measurement of the chemical composition and chemical state of the main equipment material sample after corrosion.

[0072] The thermal test is a pool boiling critical heat flux test, which measures the change in critical heat flux before and after the corrosion test of the main equipment material. If the critical heat flux decreases, it is necessary to further judge whether the nuclear fuel cladding meets the requirements of the thermal design criteria. If it is lower than the thermal design criteria, the reactor is not allowed to be restarted; if the critical heat flux increases, it is beneficial to the safety inside the reactor.

[0073] The different types of chemical shutdown poisons can be compared by using equivalent thermal neutron absorption cross sections. The equivalent thermal neutron absorption cross section of natural boron is 764, and the equivalent thermal neutron absorption cross section of natural cadmium is 2529. The equivalent results in this example are as follows.

[0074]

[0075] like Figure 3 As shown in the figure, a simplified corrosion mechanism simulation is established by using sample post-processing. The typical material of the heat transfer tube of the steam generator in a nuclear power plant is Inconel 690 alloy, which is a type of nickel-based alloy.

[0076] Before corrosion occurs, SEM observation shows that the surface of the main equipment material sample is a uniform oxide layer; XRD characterization shows that it is NiO and Cr 2 O 3 The surface is covered by an oxide film of relatively uniform composition.

[0077] In the early stage of corrosion of nickel-based alloy in boric acid environment, SEM observation of the surface of the main equipment material sample revealed that the oxide film had other irregular structures and the granular oxide increased. XPS analysis of the granular oxide showed that it was mainly composed of Ni and O, which was considered to be NiO diffusion. At the same time, XRD characterization found that the newly added NiCr 2 O 4 .

[0078] In the later stage of corrosion of nickel-based alloy in boric acid environment, SEM observation of the surface of the main equipment material sample revealed that the density of particle oxides on the surface of the oxide film increased, occupying most of the surface, indicating that the Ni element further diffused outward.

Claims

1. A test method for the corrosion of main equipment materials by chemical shutdown poisons of nuclear reactors, characterized in that: The steps include: Step 1: Sample pretreatment; Including grinding, polishing, cleaning, drying and weighing of main equipment material samples; Step 2: Experimental parameter design: including designing the type, concentration and shutdown conditions of chemical shutdown poisons, where different types of chemical shutdown poisons are compared based on equivalent thermal neutron absorption cross sections; Step 3: Cross corrosion test: including long-term static corrosion test and electrochemical test; Step 4: Sample post-processing: including rinsing, drying, weighing and necessary characterization of the main equipment material samples after corrosion; Step 5: Thermal test: including critical heat flux density test, convection heat transfer coefficient measurement and flow resistance coefficient measurement.

2. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: In step 1, the main equipment material sample materials in the sample pretreatment include zirconium alloy, austenitic stainless steel and Inconel alloy.

3. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: In the experimental parameter design of step 2, the types of chemical shutdown poisons include boric acid, cadmium nitrate and gadolinium nitrate; the concentrations of chemical shutdown poisons include the concentrations required for various types of sticking accident conditions and their concentrated concentrations; the shutdown conditions of chemical shutdown poisons include hot shutdown, cold shutdown and the transition between the two conditions.

4. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: In step 2, in the test parameter design, different types of chemical shutdown poisons are compared based on equivalent thermal neutron absorption cross sections. Since different types of chemical shutdown poisons have different equivalent thermal neutron absorption cross sections, different types of chemical shutdown poisons are required to achieve the same neutron absorption capacity, that is, different types of chemical shutdown solutions have the same shutdown capacity but different concentrations, and corrosion comparison and evaluation of different types of chemical shutdown poisons are performed.

5. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: In the experimental parameter design of step 2, different types of chemical shutdown poisons are compared based on the equivalent thermal neutron absorption cross section. Different types of chemical shutdown poisons are first compared in static corrosion rate. The larger the static corrosion rate, the stronger the static corrosion of the chemical shutdown poison. Secondly, the thickness and density of the oxide film are characterized by SEM. Different chemical shutdown poisons have different corrosion mechanisms. The formation and function of the oxide film are evaluated in conjunction with the previous static corrosion rate. XRD and XPS characterize and analyze the composition and valence changes of zirconium alloys in different types of chemical shutdown poisons, and specifically judge the influence of the composition on corrosion. The calculation formula for the static corrosion rate is (W1-W2) / h, where W1 is the weighing in the pre-test treatment, i.e. the first weighing, and W2 is the weighing in the post-test treatment, i.e. the second weighing after corrosion, and h is the corrosion test time.

6. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: In step 2, in the experimental parameter design, different types of chemical shutdown poisons are compared based on the equivalent thermal neutron absorption cross section. The higher the open circuit potential of different types of chemical shutdown poisons, the weaker the corrosion tendency of the poison. The polarization curve describes the trend of the passivation zone of different types of chemical shutdown poisons changing with concentration. Different types of chemical shutdown poisons are simulated with the same equivalent impedance spectrum to quantitatively compare the contact resistance, charge transfer resistance and constant phase angle of the electrochemical reaction solution.

7. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: In step 3, the long-period static corrosion test of the cross-corrosion test is carried out by hanging the main equipment material samples in a hydrothermal reactor. If the shutdown condition is low temperature and low pressure, it is carried out by hydrothermal cycle heating. The electrochemical test is to measure the main equipment material samples by an electrochemical workstation through a constant temperature water bath.

8. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: Step 4: The characterization of the sample post-processing includes LSCM, SEM, XRD and XPS; LSCM uses a random method to measure the arithmetic mean roughness and three-dimensional view of the main equipment material sample before and after corrosion; SEM is used to compare and observe the appearance before and after corrosion, and to distinguish the corrosion products of different properties in the surface oxide film. The main equipment material sample is cut into any thickness under different corrosion conditions to obtain the intermediate cross-section, and SEM observation is performed on the intermediate cross-section to measure the thickness of the corrosion oxide film under different corrosion conditions; further, the corrosion products of different properties are scraped and ground for XRD characterization. The XRD characterization results show the diffraction peaks of different elemental components, namely the product components; XPS performs energy spectrum analysis on the surface of the main equipment material sample before and after corrosion to obtain the content of the main elements on the surface, and at the same time verify the characteristic peaks of the components obtained in XRD.

9. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: In step 5, the critical heat flux test in the thermal test is a pool boiling critical heat flux test or a critical heat flux test under swinging conditions to meet the needs of ocean power or floating nuclear reactors; the convective heat transfer coefficient measurement includes forced convection heat transfer coefficient measurement and natural convection heat transfer coefficient measurement; the flow resistance coefficient measurement includes circular tube flow resistance coefficient, sudden change pipeline resistance coefficient, and sudden contraction pipeline resistance coefficient.

10. A test method for the corrosion of main equipment materials by chemical shutdown poisons of a nuclear reactor as claimed in claim 1, characterized in that: The oxygen concentration was less than 200 ppb during the cross corrosion test.

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