| Abstract Scope |
Nickel-base filler metals with approximately 30 wt% chromium are required for nuclear weld repair applications to ensure resistance to primary water stress corrosion cracking (PWSCC), but these higher chromium filler materials have introduced persistent metallurgical challenges related to weldability performance such as cracking (DDC, solidification and liquation cracking) and inconsistent wetting behavior. These challenges have driven successive development from Alloy 52 to 52M and most recently 52MSS-Ta. This presentation reviews the historical weldability issues that prompted each alloy refinement, supported by Framatome's field experience with associated weld failures and weldability testing data, then examines where academic and industry R&D has effectively guided field repair practice and where meaningful gaps remain between laboratory findings and field applications. Drawing on Framatome's ongoing development program with Alloy 52MSS-Ta, residual shortcomings in weld cracking resistance are discussed alongside additional factors with direct consequences for multipass weld repairs including the influence of deposit cleanliness on welding efficiency, and the effects of dilution with both vintage and modern base materials. Together, these topics illustrate the complex interplay between alloy chemistry, welding process variables, and field conditions that define the current state of practice in nuclear weld repair and the path forward for next-generation nickel-base consumables. |