Radioactive contamination of several materials following the Fukushima Daiichi Nuclear Power Station accident

Highlights: • Transport of Sr from fuel to rubble and soil was 10⁻² to 10⁻³ relative to Cs and was almost unity to accumulated water owing to successive releases from damaged fuel. • Transport of TRU was small relative to Cs via both air and water. • Transport process of ³H and ¹⁴C was different to that of other fuel components including ¹³⁷Cs. • Contamination differed in terms of radionuclide composition across reactor units #1 through #4. - Abstract: Following the 2011 accident at the Fukushima Daiichi Nuclear Power Station (NPS), which is owned by Tokyo Electric Power Co., radioactive nuclides were released into the environment and heavily contaminated the NPS site. In this study, the contamination behavior of radioactive nuclides in accumulated water, rubble, soil, and vegetation is discussed. Activity concentrations are converted to a "transport ratio," which is the activity concentration ratio normalized using the activity in the source term for the nuclides of interest and a selected standard. The transport ratio of Sr to rubble and soil by way of air was approximately 10⁻² to 10⁻³, and the successive transport to accumulated water was comparable with Cs (except for the initial release). Transport of Pu, Am, and Cm was lower than for Sr regardless of the transport process (air or water), whereas those of I, Se, and Te were comparable or greater. Contamination with ³H and ¹⁴C was independent of ¹³⁷Cs, ⁹⁰Sr, and TRU nuclides and was likely a result of different transport process.