Effects of Outside Repair Welding on the Crack Growth in the Surge Nozzle Weld on the Hot Leg Side in a Nuclear Power Plant

Na, Kyung-Hwan; Yun, Eunsub; Park, YoungSheop

Journal of KWJS 2011;29(2):34-39.
Published online May 7, 2011.

외면 보수 용접이 원전 고온관 밀림노즐에서의 결함성장에 미치는 영향

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Effects of Outside Repair Welding on the Crack Growth in the Surge Nozzle Weld on the Hot Leg Side in a Nuclear Power Plant

Kyung-Hwan Na, Eunsub Yun, YoungSheop Park

Abstract

Nickel-based austenitic alloys such as Alloy 82 and 182 had been employed as the weld metals in nuclear power plants (NPPs) due to their high corrosion resistance as well as good mechanical properties. However, since the 2000s, the occurrence of primary water stress corrosion cracking has been reported in conjunction with these alloys in domestic and oversea NPPs. In the present work, we assumed an imaginary crack at the inner surface of a surge nozzle weld that had previously experienced the outside repair welding, and constructed its finite element model. Finite element analysis was performed with respect to the heat transfer, and then to the residual stress for obtaining the total applied stress distributions. These stress distributions were finally converted to the stress intensity factors for estimating crack growth rate. From the comparison of crack growth rate curves for the cases of no repair welding and outside repair welding, it was found that the outside repair welding did not exhibit negative effect on the crack growth for the surge nozzle under consideration in this work; in both cases, the cracks stopped growing before they became the through-wall cracks.

Key Words: Dissimilar metal weld, Repair welding, PWSCC, Alloy 82/182