Definition of Reference Corrosion Rates for Performance and Safety Assessments
Diomidis, N., Guillemot, T. & King, F. (2023): Definition of Reference Corrosion Rates for Performance and Safety Assessments. Nagra Arbeitsbericht NAB 23-22.
This report defines the reference corrosion rates to be used in performance and safety assessments of a deep geological repository in Opalinus Clay. The corrosion rates can be used for: (i) the estimation of gas generation rates; (ii) the calculation of release rates of radionuclides from activated metals; (iii) the prediction of the rate of anaerobic corrosion of carbon steel canisters for spent fuel and high-level waste. The report is based on a critical review of reports and papers available in the open literature and of the results of corrosion and gas generation studies performed as part of the Nagra programme.
Additional data have become available since the last such review in 2014, resulting in an update of the reference rates. Improvements in the mechanistic understanding of the corrosion processes involved, as well as the availability of more sensitive measurement techniques and longer accumulated exposure periods for continuing experiments, have resulted in improved definitions of the corrosion rates. Reference corrosion rates are now defined for various classes of alloy (iron and carbon steel, stainless steel and Ni-based alloys, aluminium, lead, Zircaloy, copper, zinc, and magnesium) in both alkaline and near-neutral pH conditions, as well as for carbon steel in contact with compacted bentonite.