Nanosized polycrystalline diamond cladding for surface protection of zirconium nuclear fuel tubes

•Composite polycrystalline diamond layer prepared by chemical vapor deposition protect zirconium alloys nuclear fuel cladding against undesirable and dangerous surface reactions.•Protective layer consilidate zirconium alloys chemical stability and preserve its functionality.•Good radiation tolerance of the composite polycrystalline diamond layer and its protective capabilities against hot steam oxidation were confirmed. A 300nm thick polycrystalline diamond layer has been used for protection of zirconium alloy nuclear fuel cladding against undesirable oxidation with no loss of chemical stability and preservation of its functionality. Deposition of polycrystalline diamond layer was carried out using microwave plasma enhanced chemical vapor deposition apparatus with linear antenna delivery (which enables deposition of PCD layers over large areas). Polycrystalline diamond coated zirconium alloy fuel tubes were subjected to corrosion tests to replicate nuclear reactor conditions, namely irradiation and hot steam oxidation. Stable radiation tolerance of the polycrystalline diamond layer and its protective capabilities against hot steam oxidation of the zirconium alloy were confirmed. Finally, the use of polycrystalline diamond layers as a sensor of specific conditions (temperature/pressure dependent phase transition) in nuclear reactors is suggested.