Reliability Analysis Of Heat Transfer Tubes In Steam Generators Under Impact Load

The steam generator heat transfer tube,as an important component of the primary circuit,plays an important role in the energy exchange between the primary and secondary circuits,as well as in the integrity of the pressure boundary of the primary circuit system.Due to the effect of flow induced vibration,the interaction between the heat transfer tube and the supporting structure causes wear,and corrosive environments can also cause damage to the heat transfer tube.These reasons can lead to continuous degradation of structural resistance,which has a serious impact on the impact resistance performance of the steam generator heat transfer tube during service.This article analyzes the reliability of steam generator heat transfer tubes under impact load,and the specific content is as follows:(1)The yield strength,elastic modulus,and other static test data of Inconel 690 alloy,a heat transfer tube material for steam generators,were obtained through quasi-static tensile tests;The dynamic test data of Inconel 690 alloy was obtained through a split Hopkinson compression bar(SHPB)test device,and the relevant parameters of the J-C constitutive model of the material were fitted by combining dynamic and static test data.(2)The maximum likelihood method was used to calculate the three parameter Weibull distribution of the wear coefficient of steam generator heat transfer tubes.Compared with the moment estimation method,the calculation results of this method are more in line with the actual distribution of the wear coefficient.Based on this wear coefficient,the time-varying effect of wear on the heat transfer tubes of the steam generator was analyzed.In response to the randomness of pipeline corrosion,a method using NM simplex algorithm to optimize the cubic exponential smoothing method is proposed to predict pipeline corrosion.This method uses dynamic smoothing initial values and smoothing coefficients to make the prediction results more accurate.(3)Based on the BV043-85 standard,impact load was carried out on steam generator heat transfer tubes.ABAQUS secondary development function was used to achieve batch dynamic shock simulation of steam generator heat transfer tubes and obtain sample data required for reliability analysis of steam generator heat transfer tubes.Considering that the functional functions of the steam generator heat transfer tube is implicit,the instantaneous reliability of the heat transfer tube is calculated using the multiplier dimension reduction method(M-DRM)based on the principle of maximum entropy combined with the finite element simulation results.Based on the time discrete method,the time-varying reliability analysis of the structure is carried out,and the time-varying rule of the reliability of the steam generator heat transfer tube is obtained.(4)Based on the reliability analysis process in this article,a reliability analysis software for steam generator heat transfer tubes was designed.This software improves the reliability calculation efficiency of steam generator heat transfer tubes,achieves automation and visualization of reliability analysis,and provides reference for the operation and maintenance of equipment in practical engineering.This article establishes a time-varying reliability evaluation process for steam generator heat transfer tubes,and proposes a feasible time-varying reliability analysis method for structures with limit states that can only be expressed implicitly,providing reference for structural safety assessment.