Research On Non-destructive Examination Of Square Jacket For ITER Conductor

International Thermonuclear Experimental Reactor is the first fusion experimental reactor in the world.The goal is to build a superconducting Tokamak fusion experimental reactor through multinational cooperation and explore scientific and engineering feasibility to generate electricity with the usage of fusion energy,which is essential and critical step to realize commercialization of magnetic confinement fusion energy.Superconducting conductors in ITER magnetic system adopt CICC(cable-in-conduit conductors)structure,among which the jacket of ITER Poloidal Field conductor is the circular-in-square shape.As nuclear fusion device,the quality class of ITER is level 1,which means the requirements of jackets is specific and strict.However,because of especial usage of abnormal-shaped jacket,this is the first research at home and abroad.As a result,the research and innovation of non-destructive test(NDE)on jackets with abnormal shape has significant sense.With the advantages of dynamic focusing,good flexibility,visual image,high detection sensitivity and ability to detect complex-shaped objects,Phased Array Ultrasonic Testing(PAUT)has recently been highly recognized in the international NDE field,which realizes beam focusing and deflection by exciting each element with independent phase delay.For the research of NDE method on abnormal-shaped jacket,this paper originally designs a kind of NDE method which integrates PAUT and eddy current test technologies.This technology has been approved by IO experts.It has been successfully applied to the large superconducting conductors manufacture.Firstly,this paper describes background and task sense of research;investigates develop status of NDE technologies at home and aboard.After that,the merits of PAUT are discussed which provides technical feasibility to realize NDE technology research on abnormal-shaped jacket.The principle of Phase array ultrasonic test and theory of radiation sound field are explicated and establishes space models of monophyletic sound field and linear array acoustic field.Through the simulation on directivity of sound field with Matlab software,this paper deeply analyzes the array transducer parameter's influence on beam focusing deflection,which provides theoretical basis for option design of ultrasonic phased array transducer.As concerning to the NDE technical difficulties,algorithm of different arrays focus principle are carried out by using CIVA simulation platform,sound field distribution and the results of echo from artificial defect are presented under the focusing principle,An 64 times phased array ultrasonic test method are proposed.PAUT system for abnormal-shaped jacket are established to proceed confirmatory experiment and results analyzation.Finally,this paper studied the insufficient of PAUT method on abnormal-shaped jacket and confirmed non-detection zone.An experimental optimum proposals was raised.With adding phase array focusing transducer,22.5° to 45° embedded transversal defect in the abnormal-shaped jacket can be detected.In addition,acoustic field and focus principles of this transducer were simulated and its acoustic field directivity was also verified.Meanwhile,Eddy current method with the probe going through the inner bore was studied and accomplished.The distribution of eddy current density was simulated with CIVA eddy current module to confirm several key technologies,such as the optimal test frequency,filler factor and so on.Eddy current test system was established and a set of experimentations has been done to verify the system detection sensitivity.After experimental optimization and verification,a optimized NDE method with multiple arrays,44 scans PAUT method supplement with eddy current test is development.Beyond that,an innovation method with 6 exposure times was proposed for ITER PF welds which solved the density difference and decrease the test sensivity.Based on method of ITER PF jackets,a study on non-destructive examiniation of CFETR CS jackets was carried out.Meanwhie,eddy current test research for eccentricity of ITER IVC conductor was carried out and accomplished.