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Probabilistic model for pitting of copper canisters
Author(s) -
Briggs Scott,
Lilja Christina,
King Fraser
Publication year - 2021
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.202011784
Subject(s) - pitting corrosion , corrosion , copper , bentonite , probabilistic logic , environmental science , erosion corrosion of copper water tubes , saturation (graph theory) , monte carlo method , materials science , metallurgy , geotechnical engineering , mathematics , geology , statistics , combinatorics
Abstract Copper canisters for the final disposal of spent nuclear fuel are expected to be subject to general (uniform) corrosion and a limited degree of localised damage. Although the canister is expected to be exposed to predominantly active conditions, it is nevertheless prudent to assess the probability of pitting corrosion in passive conditions. A probabilistic pitting model is developed for aerobic conditions in water‐saturated bentonite. While aerobic, saturated conditions may be unlikely to occur if saturation is slow or O 2 consumption is fast, these conditions have been assumed as a starting point because of the availability of data. The model samples from environmental conditions use a Monte Carlo approach to predict active or passive conditions. Under passive conditions, the model compares corrosion potentials to breakdown and repassivation potentials to determine pit initiations and deaths, respectively. Pit depth distributions can then be calculated. For the assumed conditions, the model predicts that active conditions dominate 90% of the time while the remaining passive conditions can lead to pitting during the first few years primarily controlled by the availability of oxygen.