A dose reconstruction of ⁶⁰Co-contaminated window frames in a Taiwanese school

Since 1992, hundreds of buildings in Taiwan were discovered to have ⁶⁰Co contamination in the structural rebar. The contamination resulted from improper handling of ⁶⁰Co-contaminated scrap metal in 1982 and 1983, which subsequently was recycled and used throughout Taiwan. Hsin-hsin Kindergarten school enrolled about 600 students over the 10-y period before the contamination was discovered. Hsin-hsin Kindergarten had three ⁶⁰Co-contaminated steel window frames with measured dose rates on contact up to 150 μSv h^-1. In this study, a range of potential doses received by the Hsin-hsin Kindergarten students were estimated using ISOSHLD dose modeling software. ISOSHLD is a rapid, inexpensive screening tool to reconstruct dose ranges. To assess the potential risks to habitants of the school for the first year after construction, calculated dose rate ranges of 0.08 μSv h^-1 to 75.38 μSv h^-1 were then applied to the International Council on Radiation Protection 60 nominal detriment coefficients for stochastic effects. Risk estimates ranged from 1.46 × 10^-4 to 7.42 × 10^-4 excess fatal cancers per lifetime.