Uncertainty analysis in post-accidental risk assessment models: An application to the Fukushima accident

•Uncertainty characterization was implemented for various radioecological parameters.•Transfer calculations following the Fukushima accident were performed in SYMBIOSE.•Spatial and temporal variations of 137Cs in leafy vegetables were assessed.•Sensitivity analyses (Morris, Spearman correlation coefficients) were implemented. Environmental contamination subsequent to the atmospheric releases during the Fukushima accident resulted in high radioactive concentrations in feed and foodstuffs. Producing a realistic health risk assessment after severe nuclear accidents, and developing a sufficient understanding of environmental transfer and exposure processes, appears to be a research priority. Specifically, the characterization of uncertainties in the human ingestion pathway, as outlined by the radioecological community, is of great interest. The present work aims to (i) characterize spatial variability and parametric uncertainties raised by the processes involved in the transfer of radionuclides (134Cs and 137Cs) after atmospheric releases during the Fukushima accident into the terrestrial ecosystems, and (ii) study the impact of these variability and uncertainties on radioactive contamination of leafy vegetables. The implemented approach quantified uncertainties under a probabilistic modelling framework. This resulted in probability distributions derived mainly from Bayesian inference and by performing transfer calculations in the modelling platform SYMBIOSE.