Critical bending stress calculation method for structural integrity evaluation of 690 alloy heat transfer tube of nuclear power plant steam generator

Through a critical bending stress calculation method for the structural integrity evaluation of the 690 alloy heat transfer pipe of the nuclear power plant steam generator 690 alloy, the problem of insufficient structural integrity evaluation of the heat transfer pipe in serious accident conditions is solved, and the rapid and effective calculation of the maximum allowable bending stress of the heat transfer pipe is achieved, reducing the risk of blasting of the heat transfer pipe.

CN119720509APending Publication Date: 2025-03-28NUCLEAR POWER OPERATIONS RES INST (NPRI)
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Patent Information

Application Number
CN202411723242.3
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-11-28
Publication Date
2025-03-28

AI Technical Summary

Technical Problem

The prior art has failed to effectively evaluate and calculate the structural integrity of the steam generator 690 alloy heat transfer pipe in serious accident conditions, especially under the influence of bending loads, and the risk of the heat transfer pipe rupture accident has not been effectively identified.

Method used

A method for calculating critical bending stress in the structural integrity of the 690 alloy heat transfer pipe of the nuclear power plant steam generator 690 is provided. By determining the structural integrity limit of the internal pressure of the heat transfer pipe, calculating the critical value of the bending stress, and using the method of linear fitting and cyclic calculation of the least squares method, the calculation formula for critical bending stress is obtained.

Benefits of technology

This method can quickly and effectively calculate the maximum bending stress allowed by the heat transfer pipe, reduce the blasting risk caused by the combined action of internal pressure and bending load of the heat transfer pipe, and provides a rapid evaluation of steam generator status monitoring and operation evaluation.

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Abstract

The invention belongs to the technical field of nuclear power plant maintenance and service inspection, and particularly relates to a nuclear power plant steam generator 690 alloy heat transfer tube structure integrity evaluation critical bending stress calculation method. Comprising the following steps that 1, according to design parameters of a steam generator, the structural integrity limiting value Pcr of the inner pressure of a heat transfer pipe is determined; 2, calculating a critical value of the bending stress of the heat transfer tube; step 3, performing least square linear fitting according to the critical value obtained in the step 2, determining a slope C and an intercept D of linear fitting, and obtaining a fitting formula sigma ob = C alpha + D; step 4, determining a circumferential defect angle alpha of the heat transfer tube of the steam generator; 5, according to the value of alpha, the critical bending stress # imgabs0 # is calculated according to the following formula. The method has the advantages that by means of the method, the maximum bending stress allowed to be borne by the heat transfer pipe can be effectively, conservatively and rapidly calculated, and rapid evaluation can be provided for state monitoring and operation evaluation of the steam generator. The critical bending stress of the heat transfer tube can be limited by the method.
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