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

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.