Development of laser welded appendages to Zircaloy-4 fuel tubing (sheath/cladding)

• Examines feasibility of laser welding appendages to Zr-4 tubing.
• Laser welding minimizes the HAZ and removes toxic Be.
• Mechanical properties of laser welds appear competitive with induction brazed joints.
• Work appears promising and lays the foundation for further investigations.

Laser welding is a potential alternative to the induction brazing process commonly used for appendage attachment in CANDU® fuel fabrication that uses toxic Be as a filler metal, and creates multiple large heat affected zones in the sheath. For this work, several appendages were laser welded to tubing using different laser heat input settings and then examined with a variety of techniques: visual examination, metallography, shear strength testing, impact testing, and fracture surface analysis. Where possible, the examination results are contrasted against production induction brazed joints. The work to date looks promising for laser welded appendages. Further work on joint optimization, corrosion testing, irradiation testing, and post-irradiation examination will be performed in the future.