Development of domestic accident scenarios for risk assessment of road transport of radioactive waste in Korea

Korea is preparing for the off-site transport of spent nuclear fuel under the Special Act on the Management of High-Level Radioactive Waste but lacks a framework to quantify radionuclide releases during transport accidents and has limited data on domestic cask response. We developed a Korea-tailored source term evaluation model embedding national traffic accident statistics (2017–2021) to estimate the route specific release probability (γ). Accident scenarios described in U.S. NRC NUREG/CR-4829 and SAND2006-7723 were cross-mapped to verify scenario equivalence and to assess the applicability of U.S. cask parameters; four road class scenarios were defined to derive sequence probabilities, which were combined with U.S. severity factors to compute γ. Korean truck accident frequencies were 10–50 times higher than U.S. values; highway segments markedly suppress γ, and using an entire road average overestimates γ for highway dominant routes, whereas adopting U.S. values without localization underestimates γ by a factor of 10–30. The proposed framework yields consistent, route specific γ estimates that support licensing reviews, route optimization, and risk mitigation strategies. It also enables sensitivity analyses to quantify uncertainties in domestic data and is readily extensible to incorporate Korea-specific cask response and release fractions, as well as to couple with dose models for radiological risk assessment.