• Proceedings of the KWS Conference
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• 2000.04a
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• pp.235-238
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• 2000

• Proceedings of the KWS Conference
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• 1999.05a
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• pp.176-179
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• 1999

• Proceedings of the KWS Conference
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• 2001.05a
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• pp.94-97
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• 2001

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.241-250
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• 2003

This study, investigated the characteristics of residual stress in weldis composed of similar or dissimilar steels, are investigated byusing 3three-dimensional thermal elasto-plastic FEM analysis. The results showed that for the groove welding of the similar steels, increasedthetensile strength of the steels (POSTEN60

• Proceedings of the KWS Conference
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• 1998.10a
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• pp.87-90
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• 1998

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.557-564
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• 2009

Welding residual stress is occurred after welding process. Tensile residual stress is one factor of PWSCC. Repair welding usually happened during the manufacturing welding process. Repair welds cause strong tensile residual stress. In PWR, Repair weldments made by Alloy 82/182 is susceptible to PWSCC caused by tensile stress, material and environment. Therefore, mitigation of welding residual stress in weldments is important for reliable operating. PWOL is one of the methods for mitigation and verified for over twenty years. In this paper, residual stress distribution of repaired weldments and the effect of PWOL on mitigation is examined for surge nozzle.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.536-542
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• 2011

Dissimilar metal welds in nuclear power plant are known as very susceptible to PWSCC flaws, and periodically inspected by the qualified inspector and qualified procedure during in-service inspection period. According to field survey data, the majority of their DMWs are located on tapered nozzle or adjacent to a tapered component. These types of configurations restrict examination access and also limit examination volume coverage. Additionally, circumferential scan for axially oriented flaw is very difficult to detect located on tapered surface because the transducer can't receive flaw response from reflector for miss-orientation. To overcome this miss-orientation, it is necessary adapt skewed ultrasonic transducer accomodate tapered surface. The skewed refracted longitudinal ultrasonic transducer designed by modeling and manufactured from the modelling result for axial flaw detection. Experimental results showed that the skewed refracted longitudinal ultrasonic transducer get higher flaw response than non-skewed refracted longitudinal ultrasonic transducer.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.52-60
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• 2015

Nuclear power plant contain many dissimilar metal welds that connect carbon steel components with stainless steel pipes using alloy600 welding materials. Primary water stress corrosion cracks at dissimilar metal welds have been continuously reported around the world. In periodic integrity evaluations, dissimilar metal welds are examined using a generic ultrasonic testing procedure, KPD-UT-10. In this procedure, the gap between the probe and examination surface is limited to 1/32 inch (0.8mm). It is not easy to test some dissimilar metal welds in Korean plants applying ordinary technology because of their tapered shapes and irregular surface conditions. This paper introduces a method for applying a flexible phased array technology to improve the reliability of ultrasonic testing results for various shapes and surface conditions. The artificial flaws in specimens with irregular surfaces were completely detected using the flexible phased array ultrasonic technology. Therefore, it can be said that the technology is applicable to field examination.

• Proceedings of the KWS Conference
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• 1997.05a
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• pp.180-181
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• 1997

• Proceedings of the KWS Conference
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• 1997.05a
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• pp.51-54
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• 1997