Sparse data limit what a mechanistic corrosion model can predict
Abstract
Mechanistic corrosion models are routinely fitted with four to six parameters to a few measurements and extrapolated across service lifetimes, yet whether the data determine them is rarely tested. We identify a reduced point defect model for the duplex oxide on Nb-stabilized AISI 347 in simulated boiling-water-reactor water from published depth profiles at three exposure times, by differentiable inversion graded against a closed-form reference. Profile likelihood, a 1000-member bootstrap and a prior-relaxation test agree that one of the five parameters is undetermined and a second only weakly so, and that 95% of the fit statistic rests on three chromium points. The kinetics track an empirical power law over the calibration window but diverge from it by a factor of 3.5 to 6.3 at ten years, outside the propagated uncertainty band. That separation, not the thickness it brackets, is what these data determine; an exposure near 3000 hours would resolve it.
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BibTeX
@misc{feugmo2026sparse,
title = {{Sparse data limit what a mechanistic corrosion model can predict}},
author = {Conrard Giresse Tetsassi Feugmo},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11869},
eprint = {2609.11869},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11869},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Sparse data limit what a mechanistic corrosion model can predict
AU - Conrard Giresse Tetsassi Feugmo
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11869
UR - https://arxiv.org/abs/2609.11869
AB - Mechanistic corrosion models are routinely fitted with four to six parameters to a few measurements and extrapolated across service lifetimes, yet whether the data determine them is rarely tested. We identify a reduced point defect model for the duplex oxide on Nb-stabilized AISI 347 in simulated boiling-water-reactor water from published depth profiles at three exposure times, by differentiable inversion graded against a closed-form reference. Profile likelihood, a 1000-member bootstrap and a prior-relaxation test agree that one of the five parameters is undetermined and a second only weakly so, and that 95% of the fit statistic rests on three chromium points. The kinetics track an empirical power law over the calibration window but diverge from it by a factor of 3.5 to 6.3 at ten years, outside the propagated uncertainty band. That separation, not the thickness it brackets, is what these data determine; an exposure near 3000 hours would resolve it.
ER -