脉冲涡流检测在核电厂管道的应用

Application of Pulsed Eddy Current Detection in Pipeline of Nuclear Power Plant

[目的]为了提高换热效率,核电厂的凝结水管线、主给水管线、疏水管线及部分抽气管线管道外侧均加装了包覆层,目前对于铁磁性管道的检测手段主要为常规超声技术及超声导波技术。上述检测技术受限于检测环境及前提条件,检测难度较大。文章旨在提高带保温层管道的检测效率,丰富技术手段,缩短检修工期,提高核电厂经济效益。[方法]通过研究核电站低频电磁干扰下脉冲涡流检测方法的可行性和可靠性,利用感应电压测量值与计算值建立最优化参数反演问题,并结合参数之间的耦合关系式,根据管道脉冲涡流场时域解析解的基础上,建立感应电压测量值与计算值特定关系式,建立最优化参数反演问题,并结合参数之间的耦合关系式,提出1种针对核电厂带保温管道在役运维的脉冲涡流检测技术。[结果]利用文章提出的铁磁管道相对壁厚脉冲涡流检测方法对核电厂在役样管进行检测,并将检测结果与常规超声检测结果进行对比,得出二者检测结果误差在5%左右。[结论]脉冲涡流检测结果可靠,适用于核电厂铁磁管道壁厚腐蚀减薄的无损检测与评估。

[Introduction]In order to improve heat exchange efficiency,the condensate pipelines,main water supply pipelines drain pipelines and partial extraction pipelines of nuclear power plants are all coated outside the pipelines.At present,the test methods of ferromagnetic pipelines are mainly conventional ultrasound and ultrasonic guided waves.These test methods are limited by the detection environment and preconditions,which increase the difficulty of test.In order to improve the test efficiency of pipelines with insulation layer,we shall enrich technical methods,shorten maintenance period and improve economic benefit of nuclear power plant.[Method]This paper mainly studied the feasibility and reliability of pulsed eddy current testing method under low frequency electromagnetic interference in nuclear power plant,and used the measured and calculated values of the induced voltage to establish the optimal parameter inversion problem.In combination with the coupling relationship between the parameters and based on the time-domain analytical solution of the pipeline pulsed eddy current field,the paper established the specific relationship between the measured value and the calculated value of the induced voltage,and established the optimization parameter inversion problem.In combination with the maintenance of insulated pipes in nuclear power plants.[Result]Using the pulsed eddy current detection method for the relative wall thickness of ferromagnetic pipelines proposed in this paper,in-service sample pipelines of nuclear power plant are tested and the testing result is compared with conventional ultrasonic testing.The error of the two testing results is about 5%.[Conclusion]The testing results of impulse eddy current testing are reliable and it is suitable for non-destructive testing and evaluation of nuclear power plant ferromagnetic pipeline wall thickness corrosion thinning.