Browse > Article
http://dx.doi.org/10.20466/KPVP.2018.14.1.058

Study on Optimal Welding Processes of Half Nozzle Repair on Small Bore Piping Welds in Reactor Coolant System  

Kim, Young Zoo (한전KPS(주) (기술연구원))
Jung, Kwang Woon (한전KPS(주) 기술연구원 발전기술연구실)
Choi, Kwang Min (한전KPS(주) 기술연구원 발전기술연구실)
Choi, Dong Chul (한전KPS(주) 기술연구원 발전기술연구실)
Cho, Sang Beum (한전KPS(주) 기술연구원 발전기술연구실)
Cho, Hong Seok (한전KPS(주) (기술연구원))
Publication Information
Transactions of the Korean Society of Pressure Vessels and Piping / v.14, no.1, 2018 , pp. 58-65 More about this Journal
Abstract
The purpose of this study is to develop a Half Nozzle Repair(HNR) process to prevent the leakage from welds on small bore piping in Reactor Coolant System. The Codes & Standards of tempered bead and design requirements of J-Groove welds are reviewed. Automatic machine GTAW welding and machining equipments are developed to perform HNR process. Single pass welding and overlay welding equipments are conducted in order to obtain the optimal temper bead welding process parameters with Alloy 52M filler wire. Coarse grain heat affected zone(CGHAZ) is formed by rapid cooling rate in heat affected zone after welding. Accordingly, a proper temper bead technique is required to reduce CGHAZ in 1-Layer of welds by 2- and 3-Layers. Mock-up tests show that the developed HNR process is possible to meet ASME Code & Standard requirements without any defect.
Keywords
Alloy 600; Half nozzle repair; Primary water stress corrosion cracking; Reactor coolant system; Small bore piping;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Materials Reliability Program-220, 2007, "Review of stress corrosion cracking of alloys 182 and 82 in PWR primary water service," Electric Power Research Institute.
2 Materials Reliability Program-106, 2004, "Welding residual and operating stresses in PWR alloy 182 butt welds," Electric Power Research Institute.
3 Materials Reliability Program-115, 2004, "Crack growth rates for evaluating primary water stress corrosion cracking(PWSCC) of alloy 82, 182, and 132 welds," Electric Power Research Institute.
4 Aloraier, A. S., et al., 2004, "Eliminating post-weld heat treatment in repair welding by temper bead technique : role bead sequence in metallurgical changes," Journal of Materials Proceeding Technology, Vol. 153-154, pp. 392-400.   DOI
5 ASME Boiler & Pressure Vessel Code, Section IX, QW290, 2007, pp. 48-50.