Nuclear power station pipeline failure prediction method and equipment

Abstract

The invention relates to a nuclear power station pipeline failure prediction method and equipment. The method comprises the steps that S1, a corrosion area is determined according to actual wall thickness data of a target pipeline; s2, comparing the actual wall thickness data of the corrosion area with a preset wall thickness threshold value; s3, if the actual wall thickness data of the corrosion area is larger than a preset wall thickness threshold value, actual stress data of the corrosion area is calculated based on a finite element model, and the actual stress data of the corrosion area is compared with a preset stress threshold value; and S4, if the actual stress data of the corrosion area is larger than a preset stress threshold value, it is judged that the target pipeline fails. According to the method, the actual wall thickness and the actual stress are combined to evaluate the pipeline, the condition of the corrosion area can be evaluated more comprehensively, under the condition that the wall thickness does not exceed the threshold value but the internal stress exceeds the threshold value, the failure pipeline can be found in time, and the operation safety is improved.

Description

Technical Field

[0001] The present invention relates to the field of pipeline detection, and in particular to a method and equipment for predicting pipeline failure in a nuclear power plant. Background Art

[0002] Due to pipe wall erosion or other reasons, pipes used on-site in nuclear power plants have the problem of thinning pipe walls. Pipeline thinning will reduce the strength of the pipes, and in severe cases may cause pipe rupture or leakage, posing a threat to the safe operation of nuclear power plants. Pipeline failure caused by pipeline thinning may cause production interruption and economic losses. In the current maintenance plan, the actual wall thickness data of the in-service pipelines is mainly measured on-site, and the corrosion area is found based on the actual wall thickness data. Then, the maintenance frequency is increased for the corrosion area to avoid major accidents. However, this plan cannot fully and accurately evaluate the actual condition of the pipeline, and frequent maintenance will increase the consumption of manpower, material and financial resources, leading to an increase in maintenance costs. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method and device for predicting failure of nuclear power plant pipelines.

[0004] The technical solution adopted by the present invention to solve the technical problem is: to provide a method for predicting failure of nuclear power plant pipelines, comprising the following steps:

[0005] S1. Determine the corrosion area according to the actual wall thickness data of the target pipeline;

[0006] S2, comparing the actual wall thickness data of the corrosion area with a preset wall thickness threshold;

[0007] S3. If the actual wall thickness data of the corrosion area is greater than the preset wall thickness threshold, the actual stress data of the corrosion area is calculated based on the finite element model, and the actual stress data of the corrosion area is compared with the preset stress threshold;

[0008] S4. If the actual stress data of the corrosion area is greater than the preset stress threshold, it is determined that the target pipeline has failed.

[0009] Furthermore, after step S3, the following steps are further included:

[0010] S5. If the actual stress data of the corrosion area is less than the preset stress threshold, the stress change trend of the corrosion area is calculated, and the failure time of the corrosion area is determined according to the stress change trend, thereby determining the failure time of the target pipeline.

[0011] Further, the calculating the stress change trend of the corrosion area includes:

[0012] Calculating the wall thickness thinning rate of the corrosion area according to the actual wall thickness data of the corrosion area;

[0013] Determining a wall thickness variation trend of the corrosion region according to the wall thickness reduction rate;

[0014] The stress variation trend of the corrosion area is calculated according to the wall thickness variation trend of the corrosion area.

[0015] Further, the step S5 of determining the expiration time of the target pipeline includes:

[0016] When the target pipeline has multiple corrosion regions, the failure time of the target pipeline is determined according to the failure times of the multiple corrosion regions.

[0017] Furthermore, after step S2, the following steps are further included:

[0018] S6. If the actual wall thickness data of the corrosion area is less than the preset wall thickness threshold, it is determined that the target pipeline is failed.

[0019] Furthermore, the target pipeline corresponds to at least one evaluation standard, and the actual stress data of the corrosion area is calculated based on the finite element model in step S3, and the actual stress data of the corrosion area is compared with a preset stress threshold, including:

[0020] Based on the finite element model, respectively calculate the actual stress data of the corrosion area under each evaluation standard, and respectively compare the actual stress data under each evaluation standard with the preset stress threshold under the corresponding evaluation standard;

[0021] Step S4 includes: if the actual stress data under any evaluation standard is greater than the corresponding preset stress threshold, then the target pipeline is determined to be failed;

[0022] After step S4, the method further includes: if the actual stress data under all evaluation criteria are less than the corresponding preset stress threshold, it is determined that the target pipeline has not failed.

[0023] Furthermore, before step S3, the following steps are also included:

[0024] determining a grade of the target pipeline;

[0025] An evaluation criterion for the target pipeline is selected according to the grade of the target pipeline.

[0026] Furthermore, the actual stress data of the corrosion area calculated based on the finite element model in step S3 includes:

[0027] Extracting design stress data of nodes adjacent to the corrosion region nodes in the finite element model;

[0028] The actual stress data of the corrosion area is calculated according to the design stress data and the actual wall thickness data of the corrosion area.

[0029] Further, the calculating the actual stress data of the corrosion area according to the design stress data and the actual wall thickness data of the corrosion area comprises:

[0030] Selecting the maximum value of the design stress data of several neighboring nodes as the initial stress data of the corrosion area; or, based on the design stress data of the neighboring nodes of the corrosion area, obtaining the initial stress data of the corrosion area by interpolation calculation;

[0031] The actual stress data is calculated by combining the actual wall thickness data and the initial stress data of the corrosion area.

[0032] A nuclear power plant pipeline failure prediction device is also provided, comprising a processor and a memory storing a computer program, wherein the processor implements the steps of any of the above-mentioned nuclear power plant pipeline failure prediction methods when executing the computer program.

[0033] The implementation of the present invention has the following beneficial effects: when the actual wall thickness data of the corrosion area is greater than the preset wall thickness threshold, if the actual stress data of the corrosion area is greater than the preset stress threshold, the target pipeline is determined to be failed. By evaluating the pipeline in combination with the actual wall thickness and the actual stress, the condition of the corrosion area can be evaluated more comprehensively. When the wall thickness does not exceed the threshold but the internal stress exceeds the threshold, the failed pipeline can be discovered in time, thereby improving the safety of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0035] Figure 1 It is a schematic diagram of a flow chart of an embodiment of a method for predicting failure of a nuclear power plant pipeline according to the present invention;

[0036] Figure 2 It is a flow chart of another embodiment of the nuclear power plant pipeline failure prediction method of the present invention. DETAILED DESCRIPTION

[0037] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0038] like Figure 1 As shown, in an embodiment of the nuclear power plant pipeline failure prediction method of the present invention, the following steps are included:

[0039] S1. Determine the corrosion area based on the actual wall thickness data of the target pipeline.

[0040] S2. Compare the actual wall thickness data of the corrosion area with the preset wall thickness threshold.

[0041] S3. If the actual wall thickness data of the corrosion area is greater than the preset wall thickness threshold, the actual stress data of the corrosion area is calculated based on the finite element model, and the actual stress data of the corrosion area is compared with the preset stress threshold.

[0042] S4. If the actual stress data of the corrosion area is greater than the preset stress threshold, the target pipeline is determined to be failed.

[0043] In this embodiment, the actual wall thickness data of the pipeline can be measured using a measuring device such as an ultrasonic thickness gauge or a laser thickness gauge. The actual wall thickness data of the pipeline measured at different time points are obtained to obtain the wall thickness change of the pipeline. For example, the actual wall thickness data measured this time is compared with the actual wall thickness data measured last time. If the wall thickness of a certain area is thinned, it is determined to be a corrosion area. In other embodiments, it can also be determined to be a corrosion area after the wall thickness thinning amount of a certain area exceeds a preset thinning threshold.

[0044] When the actual wall thickness data of the corrosion area is greater than the preset wall thickness threshold, it means that the pressure that the corrosion area can currently withstand meets the requirements. The preset wall thickness threshold preferably takes the design minimum wall thickness data, and the design minimum wall thickness data refers to the minimum wall thickness determined according to the target pressure of the pipeline during the design stage. Each pipeline has corresponding design minimum wall thickness data. The corresponding design minimum wall thickness data is obtained according to the serial number information of the target pipeline, and then compared with the actual wall thickness data of the corrosion area. In other embodiments, the preset wall thickness threshold can also take other values ​​according to the actual pressure requirements.

[0045] According to the pre-established finite element model of the target pipeline, the actual stress data of the corrosion area can be calculated, wherein the use of the finite element model can improve the precision and accuracy of the stress calculation. In this embodiment, the preset stress threshold preferably refers to the design requirement stress data, and the design requirement stress data refers to the stress upper limit that the pipeline should meet in order to ensure the reliability of the pipeline in the pipeline design. Each pipeline has corresponding design requirement stress data, and the corresponding design requirement stress data is obtained according to the number information of the target pipeline, and then compared with the actual stress data. In other embodiments, the preset stress threshold can also take other values ​​according to actual needs. When the actual stress data of the corrosion area is greater than the preset stress threshold, it means that the stress in the corrosion area has exceeded the limit, and the target pipeline is judged to be failed.

[0046] Compared with the solution of using only wall thickness for evaluation, this embodiment combines actual wall thickness and actual stress to double confirm the pipeline, which can more comprehensively evaluate the condition of the corrosion area, especially when the wall thickness does not change much but the internal stress increases significantly, so that failed pipelines can be discovered in time, major pipeline failures can be prevented, major accidents can be caused, and the safety of operation can be improved.

[0047] Furthermore, if Figure 2 As shown, after step S2, the following further includes: S6, if the actual wall thickness data of the corrosion area is less than the preset wall thickness threshold, it is determined that the target pipeline is failed.

[0048] Specifically, the preset wall thickness threshold preferably designs the minimum wall thickness data. When the actual wall thickness data of the corrosion area is less than or equal to the preset wall thickness threshold, it means that the corrosion area after the wall thickness is reduced can no longer or will not meet the target pressure in the design stage, and the pipeline needs to be replaced. Therefore, the target pipeline can be directly judged as failed without stress judgment. This solution can quickly screen out pipelines with obvious failures and ensure the maintenance speed of the pipeline.

[0049] Furthermore, in step S3, calculating the actual stress data of the corrosion area based on the finite element model includes:

[0050] Extract design stress data for nodes adjacent to nodes in the corroded region of the finite element model.

[0051] The actual stress data of the corrosion area is calculated based on the design stress data and the actual wall thickness data of the corrosion area.

[0052] Specifically, the finite element model is established on the analysis software according to the current structural state of the target pipeline, and can be divided into multiple calculation nodes, each of which corresponds to an area of ​​the pipeline. According to the position of the corrosion area on the target pipeline, its corresponding node in the finite element model, that is, the corrosion area node, is determined, thereby determining all the neighboring nodes of the corrosion area node. Since the wall thickness of the neighboring nodes has not been thinned, the design stress data of these neighboring nodes can be used for analysis. The design stress data refers to the stress that the pipeline is subjected to when the design is completed.

[0053] The actual stress data of the corrosion area is calculated based on the design stress data and the actual wall thickness data of the corrosion area, including:

[0054] The maximum value of the design stress data of several adjacent nodes is selected as the initial stress data of the corrosion area; or, based on the design stress data of the adjacent nodes of the corrosion area, the initial stress data of the corrosion area is obtained by interpolation calculation. The actual stress data of the corrosion area is calculated by combining the actual wall thickness data and the initial stress data.

[0055] Specifically, since stress calculation is affected by bending moment, if a certain area of ​​the pipeline is not supported, the stress in this area generally changes monotonically. The above two methods are applicable to unsupported pipeline areas. Since the stress value at the place where the wall thickness is thinned should be less than or equal to the maximum value of the nearby area, the first method is to select the maximum value of the adjacent node as the initial stress data of the corrosion area. This value selection scheme is more conservative but simple. The second scheme is to use linear interpolation or other interpolation methods based on the relative positions of the adjacent nodes and the nodes in the corrosion area to obtain the initial stress data of the nodes in the corrosion area. This value selection scheme is more accurate. Combined with the actual wall thickness data and initial stress data of the corrosion area, the actual stress data of the corrosion area is calculated on the finite element model.

[0056] Furthermore, if Figure 2 As shown, after step S3, the following further includes: S5, if the actual stress data of the corrosion area is less than the preset stress threshold, the stress change trend of the corrosion area is calculated, and the failure time of the corrosion area is determined according to the stress change trend, thereby determining the failure time of the target pipeline.

[0057] When the actual wall thickness data of the corrosion area is greater than the preset wall thickness threshold and the actual stress data of the corrosion area is less than the preset stress threshold, it is determined that the target pipeline has not failed. The following provides a method for predicting the failure time of the pipeline:

[0058] In this embodiment, the wall thickness thinning rate of the corrosion area is calculated based on the actual wall thickness data of the corrosion area; the wall thickness change trend of the corrosion area is determined based on the wall thickness thinning rate; and the stress change trend of the corrosion area is calculated based on the wall thickness change trend of the corrosion area. Specifically, the wall thickness thinning rate is calculated using the actual wall thickness data measured multiple times in the corrosion area, and the actual wall thickness data prediction value of the corrosion area within the design life is calculated based on the current actual wall thickness data and the wall thickness thinning rate, and the wall thickness change trend is obtained. The actual wall thickness data prediction value is substituted into the finite element model for iterative calculation, and the actual stress value prediction value within the design life can be obtained, and the stress change trend of the corrosion area can be obtained. Preferably, the stress change trend is compared with the preset stress threshold, and the moment when the stress change trend reaches the preset stress threshold is the failure time of the corrosion area, which can accurately determine the failure time.

[0059] Determining the expiration time of the target pipeline in step S5 includes:

[0060] When there is only one corrosion area in the target pipeline, the failure time of the corrosion area can be used as the failure time of the target pipeline. When there are multiple corrosion areas in the target pipeline, the failure time of the target pipeline is determined according to the failure times of the multiple corrosion areas. Among them, the earliest failure time in the multiple corrosion areas is used as the failure time of the target pipeline. In other embodiments, other methods can also be used to determine the failure time of the target pipeline with multiple corrosion areas. This solution predicts the stress change trend of pipe wall thinning through the change of actual wall thickness data, thereby obtaining the failure time, which can guide preventive maintenance, avoid excessive maintenance, and improve the economy of operation and maintenance.

[0061] In an optional embodiment, the target pipeline corresponds to at least one evaluation criterion.

[0062] Before step S3, the method also includes: determining the grade of the target pipeline; and selecting an evaluation criterion for the target pipeline according to the grade of the target pipeline.

[0063] It is understandable that different pipelines may be designed based on different industry specifications, and different specifications may use one or more evaluation criteria. In this embodiment, the pipeline is divided into three levels, namely the first level, the second level and the third level. The first level includes pipelines belonging to the nuclear island, which adopt the ASME specification. The second level includes pipelines with safety levels of nuclear level 2, nuclear level 3 and NC level (non-safety level), which adopt the RCCM specification. The third level includes pipelines other than the first level and the second level, which adopt the EN13480 specification. In other embodiments, the pipeline may also be divided into other levels or use other specifications.

[0064] In step S3, the actual stress data of the corrosion area is calculated based on the finite element model, and the actual stress data of the corrosion area is compared with the preset stress threshold, which includes: calculating the actual stress data of the corrosion area under each evaluation standard based on the finite element model, and comparing the actual stress data under each evaluation standard with the preset stress threshold under the corresponding evaluation standard.

[0065] Step S4 includes: if the actual stress data under any evaluation standard is greater than the corresponding preset stress threshold, the target pipeline is determined to be failed.

[0066] After step S4, the method further includes: if the actual stress data under all evaluation criteria are less than the corresponding preset stress threshold, it is determined that the target pipeline has not failed. The stress change trend of the corrosion area under each evaluation standard is further calculated, and the failure time of the corrosion area is determined according to all stress change trends, thereby determining the failure time of the target pipeline.

[0067] The above steps are described below using a nuclear secondary pipeline as an example. The evaluation criteria that need to be considered when evaluating a nuclear secondary pipeline using the RCCM specification are shown in Table 1 (please refer to the prior art for the definition of each parameter in the table).

[0068]

[0069]

[0070] Table 1

[0071] Taking evaluation criteria (6) as an example, the left side of the inequality S SL is the actual stress data under this evaluation standard, and the right side of the inequality S h As the preset stress threshold under this evaluation standard. In the finite element model, S SL The actual stress data of the corrosion area under the evaluation standard (6) is calculated by the calculation formula, and S h For comparison. SL Less than or equal to S h , indicating that the corrosion area meets the requirements of evaluation standard (6); otherwise, it means that the corrosion area does not meet the requirements of evaluation standard (6), and the pipeline is judged to be failed. Other evaluation standards are similar to evaluation standard (6) and will not be described in detail here.

[0072] When the corrosion area meets the requirements of all evaluation criteria, it means that the corrosion area can still meet the operation requirements under design conditions, normal conditions, disturbance conditions, emergency conditions and accident conditions, so it is determined that the target pipeline has not failed. Then, based on the wall thickness thinning rate calculation, S SL , S E The actual stress data change trends of each evaluation standard are compared with the corresponding preset stress thresholds to determine the failure time under each evaluation standard. The earliest failure time under all evaluation standards is the failure time of the corrosion area.

[0073] This solution can be used for pipelines of different diameters, automatically determine the corresponding specifications of the pipelines, and then select evaluation standards for calculation, thereby improving the efficiency of analysis and calculation.

[0074] The present invention also provides a nuclear power plant pipeline failure prediction device, comprising a processor and a memory storing a computer program, wherein the processor implements the steps of the nuclear power plant pipeline failure prediction method as described in the above embodiment when executing the computer program. The nuclear power plant pipeline failure prediction device can be a computer, a server or other electronic devices.

[0075] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for predicting pipeline failure in a nuclear power plant, characterized in that: The following steps are involved: S1. Determine the corrosion area according to the actual wall thickness data of the target pipeline; S2, comparing the actual wall thickness data of the corrosion area with a preset wall thickness threshold; S3. If the actual wall thickness data of the corrosion area is greater than the preset wall thickness threshold, the actual stress data of the corrosion area is calculated based on the finite element model, and the actual stress data of the corrosion area is compared with the preset stress threshold; S4. If the actual stress data of the corrosion area is greater than the preset stress threshold, it is determined that the target pipeline has failed.

2. The nuclear power plant pipeline failure prediction method according to claim 1, characterized in that: After step S3, the method further includes: S5. If the actual stress data of the corrosion area is less than the preset stress threshold, the stress change trend of the corrosion area is calculated, and the failure time of the corrosion area is determined according to the stress change trend, thereby determining the failure time of the target pipeline.

3. The nuclear power plant pipeline failure prediction method according to claim 2, characterized in that: The calculating of the stress variation trend of the corrosion area comprises: Calculating the wall thickness thinning rate of the corrosion area according to the actual wall thickness data of the corrosion area; Determining a wall thickness variation trend of the corrosion region according to the wall thickness reduction rate; The stress variation trend of the corrosion area is calculated according to the wall thickness variation trend of the corrosion area.

4. The method for predicting failure of nuclear power plant pipelines according to claim 2, characterized in that: Determining the expiration time of the target pipeline in step S5 includes: When the target pipeline has multiple corrosion regions, the failure time of the target pipeline is determined according to the failure times of the multiple corrosion regions.

5. The method for predicting pipeline failure in a nuclear power plant according to claim 1, characterized in that: After step S2, the method further includes: S6. If the actual wall thickness data of the corrosion area is less than the preset wall thickness threshold, it is determined that the target pipeline is failed.

6. The method for predicting failure of nuclear power plant pipelines according to claim 1, characterized in that: The target pipeline corresponds to at least one evaluation standard, and the actual stress data of the corrosion area is calculated based on the finite element model in step S3, and the actual stress data of the corrosion area is compared with a preset stress threshold, including: Based on the finite element model, respectively calculate the actual stress data of the corrosion area under each evaluation standard, and respectively compare the actual stress data under each evaluation standard with the preset stress threshold under the corresponding evaluation standard; Step S4 includes: if the actual stress data under any evaluation standard is greater than the corresponding preset stress threshold, then the target pipeline is determined to be failed; After step S4, the method further includes: if the actual stress data under all evaluation criteria are less than the corresponding preset stress threshold, it is determined that the target pipeline has not failed.

7. The method for predicting failure of nuclear power plant pipelines according to claim 6, characterized in that: Before step S3, the method further includes: determining a grade of the target pipeline; An evaluation criterion for the target pipeline is selected according to the grade of the target pipeline.

8. The method for predicting pipeline failure in a nuclear power plant according to claim 1, characterized in that: The actual stress data of the corrosion area calculated based on the finite element model in step S3 includes: Extracting design stress data of nodes adjacent to the corrosion region nodes in the finite element model; The actual stress data of the corrosion area is calculated according to the design stress data and the actual wall thickness data of the corrosion area.

9. The method for predicting failure of nuclear power plant pipelines according to claim 8, characterized in that: Calculating the actual stress data of the corrosion area according to the design stress data and the actual wall thickness data of the corrosion area comprises: Selecting the maximum value of the design stress data of several neighboring nodes as the initial stress data of the corrosion area; or, based on the design stress data of the neighboring nodes of the corrosion area, obtaining the initial stress data of the corrosion area by interpolation calculation; The actual stress data is calculated by combining the actual wall thickness data and the initial stress data of the corrosion area.

10. A nuclear power plant pipeline failure prediction device, comprising a processor and a memory storing a computer program, characterized in that: The processor implements the steps of the nuclear power plant pipeline failure prediction method according to any one of claims 1 to 9 when executing the computer program.

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