Performance and evolution of cold spray Cr-coated optimized ZIRLO™ claddings under simulated loss-of-coolant accident conditions
Journal article, 2023

The performance of Cr-coated Optimized ZIRLO™ as accident tolerant fuel cladding material for pressurized water reactors (PWRs) is assessed. The coating oxidation mechanisms, oxide stability, and the transformation of the Cr-coating/Optimized ZIRLO™ interface are among the studied phenomena. For this purpose, samples were exposed at 1200°C in steam for 3 min, 20 min and 40 min. As-fabricated coated claddings, plus specimens tested in autoclave at 415°C for 90 days in simulated PWR water chemistry were employed for comparison. Characterization techniques such as scanning electron microscopy, energy dispersive x-ray spectroscopy, electron backscattered diffraction, and transmission electron microscopy were used to determine the chemistry and crystalline structure of the various phases formed during the different exposures. When exposed to loss-of-coolant accident (LOCA) conditions for 40 min, a layer of Cr2O3 up to 8 µm thick was measured on the outer surface of the Cr-coating. No significant oxidation of the underlaying Optimized ZIRLO™ alloy occurred, and the applied coating appears to be very effective at delaying the cladding degradation under accident conditions. At the coating-substrate interface, a 1–2 µm thick layer of (Cr,Fe)2Zr Laves phase was found. The presence of this phase appears to have no detrimental effects on the coating performance, and it might play a role in slowing down the dissolution of the coating into the substrate. ZrO2 particles were frequently found at grain boundaries in the coating after exposure to LOCA conditions. For longer exposure time, these particles are expected to grow into a ZrO2-network, creating a fast diffusion path for O, and compromising the oxidation protection offered by the coating.

Cold spray Cr coating

Accident tolerant fuels

High temperature steam oxidation

Loss-of-coolant accident


Andrea Fazi

Chalmers, Physics, Microstructure Physics

Mohammad Sattari

Chalmers, Physics, Microstructure Physics

Marta Krystyna Stiller

Chalmers, Physics, Microstructure Physics

Hans-Olof Andrén

Chalmers, Physics, Microstructure Physics

Mattias Thuvander

Chalmers, Physics, Microstructure Physics

Journal of Nuclear Materials

0022-3115 (ISSN)

Vol. 576 154268

Superior Accident Tolerant Fuel via Enhanced Technology (SAFETY)

Swedish Foundation for Strategic Research (SSF) (EM16-0031), 2018-02-01 -- 2023-01-31.

Subject Categories

Materials Engineering

Manufacturing, Surface and Joining Technology

Metallurgy and Metallic Materials


Chalmers Materials Analysis Laboratory

Areas of Advance

Materials Science



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