Grants and Contributions:

Grant or Award spanning more than one fiscal year (2017-2018 to 2019-2020).

Canadas nuclear reactors have produced almost 2.6 million used fuel bundles over the last decades. Thisx000D
number is expected to double over the next 40 years. Only very recently has Canada adopted a course of actionx000D
to deal with the long-term containment of the spent nuclear fuel, with the Nuclear Waste Managementx000D
Organization (NWMO) responsible for designing and implementing Canada's plan. Assessment of long-termx000D
safe and secure management options has led to the development of a centralized containment and isolation ofx000D
Canada's used fuel in a deep geological repository (DGR). What differentiates the Canadian design from othersx000D
is the corrosion-resistant outer copper coating that is proposed. As opposed to existing dual-shell overpackx000D
designs (thick copper sleeve on steel shell), the corrosion resistant copper coating is thinner (3 mm thick) andx000D
integrally bonded to the steel shell. This design reduces drastically the amount of copper required for each UFCx000D
and mechanical stresses on the steel shell. NWMO has selected electrodeposition to produce the copperx000D
coatings on the steel vessels prior to loading them with used nuclear fuel bundles and closing them with ax000D
copper coated cap end. Cold Gas Dynamic Spraying (CGDS or cold spray) was selected as the preferredx000D
technique to complete the copper coating at the containment vessel and cap end junction (closure weld zone).x000D
NWMO is still seeking a new innovative way to alleviate the use of helium in the CGDS process. Anx000D
alternative approach to enhance CGDS coating adhesion is the control of substrate temperature prior to particlex000D
impact. This proposal aims to build on few limited studies that have highlighted the potential of substratex000D
preheating as a surface preparation method prior to CGDS. It is envisioned that proper substrate heating priorx000D
to applying copper coating on steel by CGDS could result in enhanced coating adhesion strength (fromx000D
increased mechanical and metallurgical bonds) and allow the use of nitrogen only as the process gas. Thisx000D
would represent a safe, highly efficient and cost-effective solution for the CGDS coating of the closure weld zone.