NSUF 25-5507: Mechanistic Pathways of Fuel–Cladding Chemical Interactions via Ion Irradiation of Diffusion Couples

The development and qualification of advanced nuclear fuels are shifting from empirical approaches to physics-based, mechanistic models. Traditional fuel performance evaluations relied on correlations tied to specific reactor conditions, which lack predictive capability for new fuel–cladding combinations or advanced environments. While modern fuel performance codes capture fuel and cladding physics separately, a critical gap persists at the fuel–cladding interface (FCI). This region, governed by fuel–cladding chemical interaction (FCCI), involves diffusion, chemical reactivity, irradiation-driven defect accumulation, and thermally induced stresses. Despite its importance, no mechanistic FCCI model exists due to the difficulty of separating thermal and irradiation effects under reactor conditions. High-throughput ion beam irradiation offers a unique path to address this gap. Ion beams provide a controllable surrogate for neutron damage, enabling separation of displacement damage from fission product chemistry. This project will develop a high-throughput framework to quantify FCCI mechanisms as a function of temperature, irradiation, and thermal gradients. Using innovative diffusion couple designs, multiple zones of controlled interaction will be created across a single sample, allowing efficient separate- and combined-effects testing. The work will employ Nuclear Science User Facilities, utilizing the LAMDA facility for sample preparation and post-irradiation characterization and the University of Wisconsin’s Ion Beam Laboratory for proton irradiation. UO₂–Zircaloy diffusion couples will be fabricated for integration with a heating-stage irradiation platform. Samples of natural uranium will be prepared with representative microstructures. Proton implantation (~0.5 dpa over ~80 hours) will be applied under controlled gradients (350–800 °C) to emulate in-reactor thermal fields. Post-irradiation analysis will use cryogenic FIB for lift-outs, STEM-EDS for nanoscale phase mapping and concentration profiles, and nanoindentation to quantify property changes. The resulting datasets will establish the foundation for a validated, physics-based FCCI model, enabling direct implementation into advanced fuel performance codes.

Additional Info

Field	Value
Awarded Institution	Oak Ridge National Laboratory
DOI	10.46936/NSUF/60015715
Embargo End Date	2028-01-22
Facility Tech Lead	Adrien Couet, Kory Linton
Irradiation Facilities	University of Wisconsin Ion Beam Laboratory
NSUF Call	FY 2025 Super RTE Call
PI	Denise Adorno Lopes
PI Email	[email protected]
PI Phone Number	8656170743
PIE Facilities	Low Activation Materials Design and Analysis Laboratory
Project Member	Dr Denise Adorno Lopes, Senior R&D Staff Member - Oak Ridge National Laboratory (https://orcid.org/0009-0002-3705-9877)
Project Type	RTE