A method of eliminating ni-mn-si clusters in irradiated commercial pressure vessel steels and products

Abstract

The present application relates to a kind of methods for eliminating Ni-Mn-Si cluster in irradiation-damaged commercial pressure vessel steel and products.The method fixes irradiation-damaged commercial pressure vessel steel on pulse power supply, and applies pulse current for a certain time, evaluates the irradiation damage degree of commercial pressure vessel steel and sample size to determine pulse current parameters and action time.The parameter range of pulse current treatment includes frequency 1Hz-2000Hz, pulse width 10us-1ms, current 10A-3000A and action time 1min-20h.The present application can "in situ" treat irradiation-damaged commercial pressure vessel steel, thereby substantially reducing the number of Ni-Mn-Si nanoclusters and restoring the nanohardness of the material, while further reducing the temperature required to restore irradiation-damaged commercial pressure vessel steel, reducing a large amount of energy consumption, and meeting the green development trend.

Description

Technical Field

[0001] This invention belongs to the field of nuclear reactor pressure vessel life extension technology, specifically relating to a method and product for eliminating Ni-Mn-Si clusters in commercial pressure vessel steel that has been exposed to radiation damage. Background Technology

[0002] The reactor pressure vessel contains all components of the reactor core and operates under high temperature and pressure for extended periods. It is irreplaceable throughout its nuclear power plant lifespan. Therefore, ensuring the integrity and reliability of the reactor pressure vessel is crucial for the overall operational safety and lifespan of the reactor. After long-term radiation exposure, the microstructure of materials within the nuclear power pressure vessel changes. Currently, commercially available pressure vessel steel has extremely low Cu content, resulting in very few Cu clusters generated by irradiation. The primary solute atom clusters produced by irradiation are Ni-Mn-Si clusters. The high number density of Ni-Mn-Si clusters generated by irradiation damage during pressure vessel service is a significant cause of mechanical property deterioration. The number density of irradiation-induced Ni-Mn-Si clusters directly affects the material's mechanical properties. Cluster formation leads to severe degradation of the material's mechanical properties, posing a major safety hazard to the nuclear power plant.

[0003] Existing methods for repairing irradiation-damaged nuclear reactor pressure vessels involve annealing heat treatment (wet and dry methods). Patent (US5264056) discloses wet annealing using a heat transfer fluid; patent (US4708324) discloses a device for dry annealing by applying heat to the inner surface of the pressure vessel using an external heat source. While annealing can improve the long-term service life of nuclear power pressure vessels, it also presents limitations and risks. For example, over-annealing may lead to material deformation and hardening, further reducing the vessel's mechanical properties. Furthermore, annealing treatment must consider safety and cost. Both methods suffer from drawbacks such as expensive equipment, complex operation, long cycles, and high operating temperatures, which do not align with current industrial green development plans. Therefore, there is an urgent need for an efficient, energy-saving, and environmentally friendly treatment method to rapidly repair the mechanical properties of irradiated pressure vessel steel, thereby extending its service life. Summary of the Invention

[0004] In order to overcome the above-mentioned problems in the prior art, the present invention provides a method and product for eliminating Ni-Mn-Si clusters in commercial pressure vessel steel damaged by radiation, which is used to solve the above-mentioned problems in the prior art.

[0005] A method for eliminating Ni-Mn-Si clusters in commercial pressure vessel steel used to manufacture reactor pressure vessels, the method comprising the steps of:

[0006] S1. Commercial pressure vessel steel containing Ni-Mn-Si elements was selected and subjected to irradiation treatment to obtain irradiation-damaged commercial pressure vessel steel samples.

[0007] S2. Determine the Ni-Mn-Si nanocluster density and sample size of irradiated commercial pressure vessel steel samples, and determine the relevant parameters of the pre-applied pulse current;

[0008] S3. Connect the irradiated commercial pressure vessel steel sample to a pulse power supply and apply a pulse current to the sample according to the relevant parameters.

[0009] In addition to the aspects and any possible implementations described above, an implementation is further provided, wherein S1 specifically includes:

[0010] S11. Using commercial pressure vessel steel as raw material, wherein the raw material contains 0.93% Ni, 1.16% Mn, 0.32% Si, and 0.17% C, the raw material is forged, pre-heat treated, and subjected to performance heat treatment to obtain commercial pressure vessel steel;

[0011] S12. Gold ion irradiation treatment is applied to commercial pressure vessel steel.

[0012] As described above and in any possible implementation, a further implementation is provided, wherein S12 specifically includes:

[0013] The surface of commercial pressure vessel steel was mechanically polished to a mirror finish, and then subjected to ion irradiation treatment in a tandem accelerator with a flux of 2.3E15 Au. 2+ / cm 2 With a gold ion energy of 6 MeV and an irradiation temperature of 290℃, commercial pressure vessel steel simulating service damage was obtained after irradiation treatment.

[0014] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the relevant parameters in S2 include: pulse frequency of 1Hz to 1000Hz, pulse width of 10μs to 1ms, current of 10A to 3000A, and action time of 1min to 20h.

[0015] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the Ni-Mn-Si nanocluster density is 1.0 × 10⁻⁶. 24 m -3 The sample sizes are 20mm×5mm×1mm or 20mm×10mm×1mm respectively.

[0016] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the pulse current parameters are selected as a frequency of 333Hz, a pulse width of 1ms, and a current density of 9A / mm². 2 The action time is 30 minutes.

[0017] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the pulse current parameters are selected as a frequency of 333Hz, a pulse width of 1ms, and a current density of 14A / mm². 2 The action time is 15 minutes.

[0018] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the pulse current parameters are selected as a frequency of 333Hz, a pulse width of 1ms, and a current density of 17.5A / mm². 2 The action time is 10 minutes.

[0019] In addition to the aspects and any possible implementations described above, a further implementation is provided, which further includes the steps of: S4. performing hardness testing on the sample treated in S3, and S5. characterizing the sample treated in S3 using three-dimensional atomic probe microanalysis.

[0020] The present invention also provides an irradiation-damaged commercial pressure vessel steel, obtained by the method described above.

[0021] Beneficial effects of the present invention

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Pulsed current, as a special instantaneous high-energy treatment method, can rapidly reduce the number density of irradiation-induced Ni-Mn-Si clusters, thereby restoring the mechanical properties of the material. Compared with traditional annealing processes, this invention uses pulsed treatment to accelerate elemental exchange within the clusters through its additional electrical free energy, achieving the purpose of eliminating clusters, rather than being limited by Joule heating or temperature effects. Therefore, pulsed current treatment requires low operating temperatures and short processing times, allowing for "in-situ" treatment of irradiation-hardened pressure vessels directly via an external power supply, simplifying the operation. This invention achieves rapid reduction of the number density of irradiation-induced Ni-Mn-Si clusters and restoration of mechanical properties by precisely controlling the pulsed current treatment parameters, thus extending the service life of the pressure vessel. Compared with existing methods that use annealing heat treatment to restore the performance of hardened pressure vessels, this invention can treat hardened pressure vessels "in-situ" without adjusting the primary coolant temperature or moving the reactor core, reducing the number density of Ni-Mn-Si nanoclusters in the matrix and maximizing the rapid restoration of the mechanical properties of the hardened pressure vessel. This invention does not require additional heat sources, requires less time, and can significantly reduce energy consumption, meeting the requirements of current industrial green development plans. Attached Figure Description

[0024] Figure 1 For Example 1 of the present invention, an APT image of the distribution of Ni-Mn-Si nanoclusters in an irradiated commercial pressure vessel steel matrix was selected.

[0025] Figure 2 For Example 1 of the present invention, an APT image of the distribution of Ni-Mn-Si nanoclusters in a commercial pressure vessel steel matrix was taken after pulsed current processing.

[0026] Figure 3 This is a schematic diagram comparing the nano-indentation hardness results before and after pulse treatment of irradiated commercial pressure vessel steel, as used in an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram showing the density comparison of Ni-Mn-Si nanoclusters before and after pulse treatment of irradiated commercial pressure vessel steel in Example 1 of the present invention.

[0028] Figure 5 This is a flowchart of the method of the present invention. Detailed Implementation

[0029] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0030] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0031] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0032] like Figure 5 As shown, the present invention discloses a method for eliminating Ni-Mn-Si clusters in commercial pressure vessel steel that is used to manufacture reactor pressure vessels. The method includes the following steps:

[0033] S1. Pressure vessel steel containing Ni-Mn-Si was selected and subjected to irradiation treatment to obtain irradiation-damaged commercial pressure vessel steel samples;

[0034] S2. Determine the Ni-Mn-Si nanocluster density and sample size of irradiated commercial pressure vessel steel samples, and determine the relevant parameters of the pre-applied pulse current;

[0035] S3. Connect the irradiated commercial pressure vessel steel sample to a pulse power supply and apply a pulse current to the sample according to the relevant parameters;

[0036] S4. Perform hardness testing on the sample after S3 treatment;

[0037] S5. The sample processed by S3 is characterized using three-dimensional atomic probe technology.

[0038] The method of this invention can quickly repair the performance degradation caused by high-density nanoclusters, so as to restore the performance of irradiated damaged containers to the greatest extent and thus extend the service life of pressure vessels.

[0039] The invention consists of the following steps: First, commercial pressure vessel steel is hardened by gold ion irradiation to obtain a hardened material with high-density Ni-Mn-Si nanoclusters. Then, using this material as the research object, the number density of Ni-Mn-Si nanoclusters in the hardened material matrix is ​​rapidly reduced by controlling the pulse current parameters, thereby reducing the nanohardness of the material and achieving the purpose of repairing irradiated damaged pressure vessel steel.

[0040] This invention utilizes pulsed current to eliminate clusters in commercial pressure vessel steel damaged by radiation and restore its performance. The method involves pulse treatment of radiation-hardened simulated steel, with the following parameters: frequency 1Hz~1000Hz, pulse width 10μs~1ms, current 10A~3000A, and treatment time 1min~20h.

[0041] Furthermore, the specific steps of the pulse processing consist of the following:

[0042] (1) Determine the hardening degree of the irradiated simulated steel and the size of the pulse-treated sample, and determine the pulse current treatment parameters based on the hardening degree and sample size.

[0043] (2) After the irradiated simulated steel is fixed by a clamp, it is connected to the pulse power supply with pure copper wire and subjected to pulse current processing according to the given parameters.

[0044] The appropriate pulsed current treatment parameters were selected based on the hardening degree of the commercial pressure vessel steel and the sample size: the commercial pressure vessel steel was model A508-3, irradiated at 290℃, with an irradiation dose of 10 dpa (displacement per atom), and sample size of 20mm × 5mm × 1mm. The pulsed current parameters were selected as follows: frequency 333Hz, pulse width 1ms, and current density 9A / mm². 2The irradiation time was 30 min; the pressure vessel steel was irradiated at 290℃ with an irradiation dose of 10 dpa. The sample size was 20 mm × 10 mm × 1 mm. The pulse current parameters were selected as follows: frequency 333 Hz, pulse width 1 ms, and current density 14 A / mm². 2 The irradiation time was 15 min; the pressure vessel steel was irradiated at 290℃ with an irradiation dose of 10 dPa. The sample size was 20 mm × 10 mm × 1 mm. The pulse current parameters were selected as follows: frequency 333 Hz, pulse width 1 ms, and current density 17.5 A / mm². 2 The action time is 10 minutes.

[0045] The equipment used for pulse processing is a pulse power supply.

[0046] When the method is applied to actual reactor pressure vessels, the larger the size of the commercial pressure vessel steel, the higher the frequency, the wider the pulse width, the larger the current, and the longer the action time, which ranges from 1 hour to 10 hours.

[0047] The method further includes step (3): hardness testing of the pulse-treated sample by preparing a nanoindentation test sample, wherein step (3) specifically includes:

[0048] 3-1: The Ni-Mn-Si nanocluster density of the sample after pulsed current treatment was obtained by using three-dimensional atom probe technology and compared with the Ni-Mn-Si nanocluster density of the sample before pulsed current treatment.

[0049] 3-2: Preparation of nanoindentation samples and recording of nanohardness changes before and after pulsed current treatment.

[0050] The pulse treatment of the irradiated commercial pressure vessel steel was carried out at room temperature. Under real-world conditions, Ni-Mn-Si nanoclusters belong to the "post-explosion phase," and the cluster size is very small. To accelerate the experimental process, commercial pressure vessel steel was used as the raw material in the following examples. The raw material contained 0.93% Ni, 1.16% Mn, 0.32% Si, and 0.17% C. All elements met the composition requirements for nuclear power pressure vessel steel, and their contents were within the design range for nuclear power pressure vessels. Forging, pre-heat treatment, and performance heat treatment processes were developed based on the industrial production process of pressure vessels. Due to the high risk of neutron irradiation of materials under real-world conditions, laboratory gold ion irradiation was used to simulate service conditions for treating the commercial pressure vessel steel. The sample sizes of the commercial pressure vessel steel were 20mm × 5mm × 1mm or 20mm × 10mm × 1mm. The surface was mechanically polished to a mirror finish, and then placed in a 2×3MV tandem accelerator for ion irradiation treatment with a flux of 2.3E15 Au. 2+ / cm 2The gold ion energy was 6 MeV, and the irradiation temperature was 290°C. After irradiation treatment, pressure vessel steel simulating service damage was obtained, with the damage degree gradually decreasing with increasing depth. The current parameters selected for the treated samples avoided the skin effect. A pulsed current was applied to the entire sample of the example.

[0051] Example 1:

[0052] This embodiment applies pulsed current treatment to small-sized radiation-hardened pressure vessel steel. The specific steps are as follows:

[0053] Step 1: Prepare the pulse-treated sample. Take a 20mm × 5mm × 1mm irradiation sample and polish all surfaces except the irradiated surface to a mirror finish using 600, 1500, and 2000 grit sandpaper in sequence to ensure good contact with the pulse electrode. For example... Figure 1 As shown, Ni-Mn-Si elements accumulate in large quantities in irradiated pressure vessel steel, producing a large number of Ni-Mn-Si clusters.

[0054] Step 2: Determine the pulse processing parameters. Set the pulse current parameter range, and determine the following parameters: frequency 333Hz, pulse width 1ms, current density 9A / mm². 2 The action time is 30 minutes. 333Hz is a low-frequency pulsed current; low-frequency pulsed current has a significant non-thermal effect. 1ms is the period during which the pulse can reach its maximum value. 9A / mm 2 This refers to the current density required to reach the target temperature; 30 minutes is the reaction time for dissolving Ni-Mn-Si clusters.

[0055] Step 3: Pulsed Current Treatment. The polished small sample is fixed to the output of the pulse power supply using a fixture and subjected to pulsed current treatment for 30 minutes at room temperature. Argon gas is used for protection during the treatment to prevent surface oxidation. Figure 2 As shown, most of the clusters in the pressure vessel steel were dissolved after pulsed current treatment. During the pulsed treatment, the difference in conductivity between the irradiated pressure vessel steel matrix and the nanoclusters resulted in high current density regions between the clusters. Since current density is proportional to the diffusion coefficient, the current density was higher between closely packed nanoclusters, significantly accelerating element exchange. This caused iron atoms in the matrix to replace Ni-Mn-Si atoms in the clusters, continuously reducing the number of Ni-Mn-Si atoms in the clusters until the elemental composition of the matrix and the nanoclusters was essentially the same, i.e., complete dissolution. The current parameters selected for the treated samples avoided the skin effect. The pulsed current was applied to the entire sample in this example.

[0056] Step 4: The most direct indicator of cluster repair in pressure vessel steel is the change in hardness. Therefore, nanoindentation detection is performed on the irradiated samples after pulse treatment to compare the changes in microscopic hardness before and after pulse current treatment. For example... Figure 3 The irradiated pressure vessel steel showed a significant increase in hardness. After pulse processing, the hardness of the simulated service pressure vessel was quickly restored, returning it to the original sample state.

[0057] Step 5: Due to the small size of Ni-Mn-Si nanoclusters in pressure vessel steel (only 2-3 nm), ordinary characterization methods cannot observe changes in these clusters. Therefore, three-dimensional atomic probe microanalysis (3D Atom Probe) is required to observe the distribution of Ni-Mn-Si nanoclusters in the matrix. Before cluster characterization, the irradiated damaged sample and the pulsed treated sample are processed using a focused ion beam (FIB) to extract a portion of the example sample. This extract is then used to create the sample required for 3D Atom Probe characterization. The required sample is needle-shaped, with circumferential cutting to achieve the required curvature and length. The main part of the needle tip is the original silicon stage. The extracted irradiated damaged sample and pulsed treated sample are located at the tips of these needles. This invention uses FIB to cut the sample surface, ultimately obtaining a characterization sample located at a depth of approximately 400-500 nm in the irradiated layer of the pressure vessel steel. This depth represents the most severely damaged area and can simulate the overall condition of the pressure vessel steel. The total length of the needle is 175 nm, and the tip diameter is 15 nm. Figure 4 As shown, the number density of Ni-Mn-Si clusters before treatment is 1.0 × 10⁻⁶. 24 m -3 The average size was 0.81±0.02 nm, and the volume fraction was 0.9±0.004%. After pulse treatment, the number density of Ni-Mn-Si clusters was 2.9×10⁻⁶. 23 m -3 The average size was 0.60±0.02 nm, and the volume fraction was 0.24±0.002%. It can be seen that after pulsed current treatment, the number density of Ni-Mn-Si clusters decreased by 71%, the average size decreased by 0.21 nm, and the volume fraction decreased by 74%. Compared to the difficulty in eliminating Ni-Mn-Si nanoclusters in nuclear power pressure vessels in existing technologies, this invention uses pulsed current to repair simulated damaged pressure vessel steel in this embodiment, restoring the hardness of commercial pressure vessel steel, dissolving Ni-Mn-Si clusters in the pressure vessel steel, and significantly reducing cluster density, size, and volume fraction. This achieves rapid, efficient, and in-situ repair of damaged pressure vessel steel used in nuclear power plants, restoring its performance.

[0058] Example 2:

[0059] This embodiment applies pulsed current treatment to small-sized radiation-hardened pressure vessel steel. The specific steps are as follows:

[0060] Step 1: Prepare the pulse treatment sample. Take a 20mm×10mm×1mm irradiation sample and polish all surfaces except the irradiated surface with 600, 1500, and 2000 grit sandpaper until they are mirror-finished to ensure good contact with the pulse electrode.

[0061] Step 2: Determine the pulse processing parameters. Set the pulse current parameter range, and determine the following parameters: frequency 333Hz, pulse width 1ms, current density 14A / mm². 2 The action time is 15 minutes. 333Hz is a low-frequency pulsed current; low-frequency pulsed current has a significant non-thermal effect. 1ms is the period during which the pulse can reach its maximum value. 14A / mm 2 This is the current density required to reach the target temperature, and 15 minutes is the reaction time for dissolving Ni-Mn-Si clusters.

[0062] Step 3: Pulsed Current Treatment. The polished small-sized sample was fixed to the output of the pulse power supply using a fixture and subjected to pulsed current treatment for 15 minutes at room temperature. Argon gas was used for protection during the treatment to prevent surface oxidation. During the pulse treatment, the difference in conductivity between the irradiated pressure vessel steel substrate and the nanoclusters resulted in high current density regions between the clusters. Since current density is proportional to the diffusion coefficient, the current density is higher between closely packed nanoclusters, significantly accelerating element exchange. This causes iron atoms in the substrate to replace Ni-Mn-Si atoms in the clusters, continuously reducing the number of Ni-Mn-Si atoms in the clusters until the elemental composition of the substrate and the nanoclusters is essentially the same, i.e., complete dissolution. The current parameters selected for sample treatment avoided the skin effect. The pulsed current was applied to the entire sample in this embodiment.

[0063] Step 4: The most direct indicator of cluster repair in pressure vessel steel is the change in hardness. Therefore, nanoindentation detection is performed on the irradiated samples after pulse treatment to compare the changes in microscopic hardness before and after pulse current treatment. For example... Figure 3 The irradiated pressure vessel steel showed a significant increase in hardness. After pulse processing, the hardness of the simulated service pressure vessel was quickly restored, essentially returning to the original sample state.

[0064] Step 5: Due to the small size of Ni-Mn-Si nanoclusters in pressure vessel steel (only 2-3 nm), ordinary characterization methods cannot observe changes in these clusters. Therefore, three-dimensional atomic probe microanalysis (3D Atom Probe) is required to observe the distribution of Ni-Mn-Si nanoclusters in the matrix. Before cluster characterization, focused ion beam (FIB) was used to process the irradiated damaged and pulsed samples, extracting a portion of the example sample to create the 3D Atom Probe sample required for characterization. The required sample was needle-shaped, circumferentially cut to achieve the required curvature and length. The main part of the needle tip was the original silicon stage. The extracted irradiated damaged and pulsed samples were located at the tips of the respective needles. In this study, FIB was used to cut the sample surface, ultimately obtaining a characterization sample located at a depth of approximately 400-500 nm in the irradiated layer of the pressure vessel steel. This depth represents the most severely damaged area and can simulate the overall condition of the pressure vessel steel. The total length of the needle was 180 nm, and the tip diameter was 16 nm. Eliminating Ni-Mn-Si nanoclusters in nuclear power pressure vessels is quite difficult. In this embodiment, pulsed current is used to repair simulated damaged pressure vessel steel, restoring the hardness of commercial pressure vessel steel and dissolving Ni-Mn-Si clusters in the pressure vessel steel, significantly reducing cluster density, size, and volume fraction. This achieves rapid, efficient, and in-situ repair of damaged pressure vessel steel used in nuclear power plants, restoring its performance.

[0065] Example 3:

[0066] This embodiment applies pulsed current treatment to small-sized radiation-hardened pressure vessel steel. The specific steps are as follows:

[0067] Step 1: Prepare the pulse treatment sample. Take a 20mm×10mm×1mm irradiation sample and polish all surfaces except the irradiated surface with 600, 1500, and 2000 grit sandpaper until they are mirror-finished to ensure good contact with the pulse electrode.

[0068] Step 2: Determine the pulse processing parameters. Set the parameter range for the pulse current, and determine the following parameters: frequency 333Hz, pulse width 1ms, current density 17.5A / mm². 2 The action time was 10 minutes. 333Hz was a low-frequency pulsed current; low-frequency pulsed current has a significant non-thermal effect. 1ms was the period during which the pulse could reach its maximum value, 17.5 A / mm. 2 This refers to the current density required to reach the target temperature, and 10 minutes is the reaction time for dissolving Ni-Mn-Si clusters.

[0069] Step 3: Pulsed Current Treatment. The polished small-sized sample was fixed to the output of the pulse power supply using a fixture and subjected to pulsed current treatment for 10 minutes at room temperature. Argon gas was used for protection during the treatment to prevent surface oxidation. During the pulse treatment, the difference in conductivity between the irradiated pressure vessel steel substrate and the nanoclusters resulted in high current density regions between the clusters. Since current density is proportional to the diffusion coefficient, the current density is higher between closely packed nanoclusters, significantly accelerating element exchange. This causes iron atoms in the substrate to replace Ni-Mn-Si atoms in the clusters, continuously reducing the number of Ni-Mn-Si atoms in the clusters until the elemental composition of the substrate and the nanoclusters is essentially the same, i.e., complete dissolution. The current parameters selected for sample treatment avoided the skin effect. The pulsed current was applied to the entire sample in this embodiment.

[0070] Step 4: The most direct indicator of cluster repair in pressure vessels is the change in hardness. Therefore, nanoindentation detection is performed on the irradiated samples after pulse treatment to compare the changes in microscopic hardness before and after pulse current treatment. For example... Figure 3 The irradiated pressure vessel steel showed a significant increase in hardness. After pulse processing, the hardness of the simulated service pressure vessel was quickly restored, essentially returning to the original sample state.

[0071] Step 5: Due to the small size of Ni-Mn-Si nanoclusters in pressure vessel steel (only 2-3 nm), ordinary characterization methods cannot observe changes in these clusters. Therefore, three-dimensional atomic probe microanalysis (3D Atom Probe) is required to observe the distribution of Ni-Mn-Si nanoclusters in the matrix. Before cluster characterization, the irradiated damaged samples and pulsed treated samples were processed using a focused ion beam (FIB) to extract a portion of the example sample. This extracted sample was then used to create the 3D Atom Probe for characterization. The required sample was needle-shaped, with circumferential cutting to achieve the required curvature and length. The main part of the needle tip was the original silicon stage. The extracted irradiated damaged and pulsed treated samples were located at the tips of these needles. In this study, the sample surface was cut using an FIB, ultimately obtaining a characterization sample located at a depth of approximately 400-500 nm in the irradiated layer of the pressure vessel steel. This depth represents the most severely damaged area and can simulate the overall condition of the pressure vessel steel. The total length of the needle was 178 nm, and the tip diameter was 16 nm. Eliminating nanoclusters has always been challenging. In this embodiment, pulsed current is used to repair simulated damage to pressure vessel steel, restoring the hardness of commercial pressure vessel steel and dissolving Ni-Mn-Si clusters in the pressure vessel steel, significantly reducing cluster density, size, and volume fraction. This achieves rapid, efficient, and in-situ repair of pressure vessel steel damaged in nuclear power plant service and restores its performance.

[0072] The present invention also provides an irradiation-damaged commercial pressure vessel steel. The mechanical properties of the irradiation-damaged commercial pressure vessel steel obtained by the method described in the present invention are significantly restored after eliminating or reducing Ni-Mn-Si clusters.

[0073] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for eliminating Ni-Mn-Si clusters in irradiated commercial pressure vessel steel, characterized in that, The commercial pressure vessel steel is used to manufacture reactor pressure vessels, and the method includes the steps of: S1. Commercial pressure vessel steel containing Ni-Mn-Si elements was selected and subjected to irradiation treatment to obtain irradiation-damaged commercial pressure vessel steel samples, specifically including: S11. Using commercial pressure vessel steel as raw material, wherein the raw material contains 0.93% Ni, 1.16% Mn, 0.32% Si, and 0.17% C, the raw material is forged, pre-heat treated, and subjected to performance heat treatment to obtain commercial pressure vessel steel; S12. Gold ion irradiation treatment of commercial pressure vessel steel; S2. Determine the Ni-Mn-Si nanocluster density and sample size of irradiated commercial pressure vessel steel samples, and determine the relevant parameters of the pre-applied pulse current. The Ni-Mn-Si nanocluster density is 1.0 × 10⁻⁶. 24 m -3 The sample sizes are 20mm×5mm×1mm or 20mm×10mm×1mm respectively. The relevant parameters include: pulse frequency of 1Hz~1000Hz, pulse width of 10μs~1ms, current of 10A~3000A, and action time of 1min~20h. S3. Connect the irradiated commercial pressure vessel steel sample to a pulse power supply and apply a pulse current to the sample according to the relevant parameters.

2. The method for eliminating Ni-Mn-Si clusters in commercial pressure vessel steel damaged by radiation according to claim 1, characterized in that, S12 specifically includes: The surface of the commercial pressure vessel steel was mechanically polished to a mirror finish, and then subjected to ion irradiation treatment in a tandem accelerator with a flux of [missing value]. With a gold ion energy of 6 MeV and an irradiation temperature of 290℃, commercial pressure vessel steel simulating service damage was obtained after irradiation treatment.

3. The method for eliminating Ni-Mn-Si clusters in commercial pressure vessel steel damaged by radiation according to claim 2, characterized in that, It also includes the following steps: S4. Perform hardness testing on the sample after S3 treatment; S5. The sample processed by S3 is characterized using three-dimensional atomic probe technology.

4. An irradiation-damaged commercial pressure vessel steel, characterized in that, Obtained by the method described in any one of claims 1-3.

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