Overview of oxidation tests results of austenitic alloys coated by CrN and NiCrAIY in high temperature steam environments

The current development of accident-tolerant fuel (ATF) claddings aims at improving the high temperature integrity of new solutions over existing zirconium claddings. Characterization of the newly-proposed cladding materials is essential in order to assess their feasibility for commercial use. The cladding material should tolerate loss of forced cooling for a significant period without failing. This paper describes the experimental work done at VTT on a candidate cladding solution by using a high temperature steam furnace capable of achieving temperatures up to 1600°C. Experiments were performed on Alloy 800H, NiCrAlY coated Alloy 800H tubes, and CrN coated AISI3 16L coupon specimens at the temperature of 1200°C in flowing steam conditions. Post-test analyses are reported in terms of weight change measurements and microstructural observations by using 'state of the art' electron microscopes. (author)