Callaway nuclear plant through-wall crack repair using ASME case N-504

摘要

In October 1995, Union Electric Company's Callaway Nuclear Plant was shut down due to Reactor Coolant System leakage. The leakage source was a through-wall flaw in a non-isolable, 2-inch NPS ASME Class 1 stainless steel elbow. Traditional repair methods would have required fuel offload with extensive plant downtime. Fuel offload was avoided using ASME Code Case N-504, which permits an "engineered weld overlay" in lieu of defect removal. Union Electric Company successfully implemented this repair and returned the Callaway Plant to operation nine days after the leak was discovered.