核电厂管道局部壁厚减薄快速评定方法研究

Study of the Rapid Evaluation Method for Locally Wall-Thinned Pipe of Nuclear Power Plant

目的解决核电厂实际运行中管道壁厚局部减薄缺陷快速评定的需求。方法基于RCC-M规范的设计基本要求和核电厂管道评估的实践经验,基于3个工程化的分析假设,提出一种管道壁厚减薄的快速评定方法。其包含三部分内容:1)最小壁厚计算;2)结构完整性评价;3)功能性评价。分别采用管道壁厚减薄快速评定方法和SYSPIPE软件有限元分析方法对管道减薄案例进行分析。结果1)最小壁厚满足要求;2)管道完整性分析中,正常工况下应力比偏差最大值为0.26,设计工况应力比偏差为0,扰动工况应力比偏差为0.03,紧急工况应力比偏差为0.04,事故工况应力比偏差为0.03;3)管道功能性分析中,一次应力比偏差为0,二次应力比偏差为0.27。在管道正常工况下的完整性评定和管道功能性分析中,开发的管道壁厚减薄快速评定方法分析结果较SYSPIPE软件分析更安全和保守,在其他工况下两者计算结果基本一致。结论管道壁厚减薄快速评定方法是一种通用的工程实践方法,并在国内多个核电机组得到工程实践应用,为电厂实际运行提供了一种快速、可靠的技术分析方法。

The purpose of this paper is to get a rapid and reliable engineering method to evaluate the safety of local thinned pipeline in nuclear power plants.The research method of this paper is based on the basic requirements in the design code of RCC-M and the experience of engineering practical,and three engineering hypotheses are assumed.A method of rapid evaluation for local thinned pipeline is proposed which includes three parts:1)calculation of minimum wall thickness;2)structural in tegrity evaluation;3)functional evaluation.Both the rapid evaluation method for locally thinned pipe and the finite element analysis method of SYSPIPE software are used to analyze the study case.The results show that:1)the minimum wall thickness meets the requirements;2)the maximum stress ratio deviation is 0.26 under the normal condition,0 under design condition,0.04 under emergency condition,0.03 under disturbance condition,and 0.03 under accident condition,respectively;3)In the pipeline functional analysis,the deviation of primary stress ratio is 0 and the deviation of secondary stress ratio is 0.27,respectively.The rapid assessment method of pipe wall thickness thinning is safer and more conservative than the SYSPIPE software analysis in the normal working conditions of the pipeline integrity assessment and the secondary stress assessment of the pipeline functional analysis.And the calculation results of the two methods are basically consistent in other conditions.The method proposed in this paper is a general engineering practice,and it has be applied in many nuclear power stations in China,and it provides a rapid and reliable technical analysis method for the actual operation of power plants.