• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.1
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• pp.29-39
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• 1993

초음파탐상검사는 그 검사결과가 여타 비파괴검사법에 비해 검사자, 검사장비, 절차서 등 검사 시스템에의 의존도가 높으며, 이중에서도 특히 검사자의 능력과 숙련도에 크게 좌우된다. 따라서 검사결과의 신뢰도를 높이기 위해서는 무엇보다도 검사자에 대해 엄격한 자격인정(Qualification)이 필요하다. 초음파탐상검사는 원자력 발전소 기기의 가동전중검사시 가장 많이 적용하는 체적검사법으로써, 결함검출 및 평가의 신뢰도를 확보하기 위하여 최근 관련 기술기준에서는 검사자에 대해 보다 엄격한 자격인정을 요구함과 아울러 초음파탐상검사 시스템(검사자, 장비, 절차서)에 대한 기량검증(Performance Demonstration)까지를 요구하고 있다. 위의 두 가지 요건을 성공적으로 충족시킬 수 있다면, 초음파탐상기술의 신뢰도는 크게 향상될 것이다. 본고에서는 최근 보다 강화된 원전 가동전중검사 초음파탐상검사 요원의 자격인정요건에 대해 자세히 알아봄으로써 관련 국내 기술기준의 제정과 앞으로 국내 원전 초음파탐상 검사요원에 대한 본 자격인정요건의 적용에 대비코자 하였다. 한편, "초음파탐상검사 시스템에 대한 기량검증 요건"은 초음파탐상 검사요원의 자격인정 요건과 밀접한 관계가 있으므로 다음에 별도로 기술코자 한다.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.1
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• pp.310-317
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• 1995

Crack detection technique by ultrasonics in structures and components made of austenitic stainless steel often loses its reliability due to the material characteristics during inservice inspection of nuclear power plants, especially in the area of detection and sizing in centrifugally cast stainless steel pipings. In order to understand and overcome this problem, computer program for tracing the ultrasonic rays within material has been developed to simulate the process of defect detection within weld. The program simulates through transmission and reflection technique in crack detection of austenitic stainless steel as well as ultrasonic beam propagation through multiple media including stainless steel cladding interface.

• The Journal of the Acoustical Society of Korea
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• v.16 no.1
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• pp.5-9
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• 1997

If small cracks in stud bolts are not detected early enough, they grow rapidly and cause total fracture. It is difficult to detect, prior to failure, flaws such as stress-corrosion cracking in thread roots and corrosion wastages using conventional ultrasonic testing methods during inservice inspection. This study show a method of detecting a small crack by digital signal processing. When ultrasonic beams travels into threads in parallel way, the echoes from each successive threads has almost the same intervals between any two signals. We can estimate the next thread signal based on previous thread signal by the predictive distance. The optimized operator is used to remove the predicted successive thread signals so that a small crack signal can be detected.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.5
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• pp.389-397
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• 1998

For an effective and efficient management of large amounts of preservice/inservice inspection(PSI/ISI) data in nuclear power plants, an intellegent Windows 95-based data management program was developed. This program enables the prompt extraction of previously conducted PSI/ISI conditions and results so that the time-consuming data management, painstaking data processing and analysis in the past are avoided. The program extracts, and the associated remedies. Furthermore, additional inspection data and comments can be easily added or deleted for subsequent PSI/ISI operation. Although the initial version of the program was applied to Kori nuclear power plant, this program can be equally applied to other nuclear power plant. And also this program can be used to offer the fundamental data for application of evaluation data related to fracture mechanics analysis(FMA), probabilistic reliability assessment(PRA) of PSI/ISI results, performance demonstration initiative(PDI) and risk-informed ISI based on probability of detection(POD) information of ultrasonic examination. Besides, the program can be further developed as a unique PSI/ISI data management expert system that can be apart of PSI/ISI data management expert system that can be a part of PSI/ISI Total Support System(TSS) for Korean nuclear power plants.