Detailed Analysis of the Debris-Fretting Damage Areas on Coated Fuel Cladding.

Fuel failure caused by fretting damage to cladding remains a relevant issue despite decades of research and development aimed at enhancing the physical parameters of fuel. This paper presents the results of experiments conducted at the Research Centre Řež on Zr-1%Nb alloy tube specimens covered with protective coatings made of chromium (Cr) and nitrogen (N) compounds. The experiments involved debris-fretting tests under dry conditions at room temperature as well as microscopic measurements of groove depths.

Anaerobic microbial corrosion of carbon steel under conditions relevant for deep geological repository of nuclear waste.

We examined microbial corrosion of carbon steel in synthetic bentonite pore water inoculated with natural underground water containing microorganisms over a period of 780-days under sterile and anaerobic conditions. Corrosion behaviour was determined using the mass loss method, SEM-EDS analysis and Raman spectroscopy, while qualitative and quantitative changes in the microbial community were analysed using molecular-biological tools (16S rDNA amplicon sequencing and qPCR analysis, respectively). Corrosion rates were significantly higher in the biotic environment (compared with an abiotic environment), with significant localisation of corrosion attacks of up to 1 mm arising within 12-months.