A Study on the transport of radiocaesium in the environment of Fukushima

Sato, Haruo

The accident at the TEPCO Fukushima Dai-ichi Nuclear Power Plant in March 2011, led to the release of volatile radionuclides which were deposited on the surrounding environment (soils, forests, residential land, etc.) around the Fukushima Pref. Radiocaesium is now the main contributor to radiological dose because I-131, of which half-life is as short as about 8 days, disappeared. While a decontamination activity got into stride since the act on Special Measures Concerning the Handling of Radioactive Pollution, came fully into force on January 1, 2012, any forest bodies sharing about 70 % of the total areas have a chance of decontaminating. Therefore, forests in addition to much contaminated rivers and dams are still the source of radiocaesium, which is possible to gradually move to downstream areas. Evaluation in the change of radiation dose accompanying movement and re-distribution of radiocaesium and evaluation of re-contamination are indispensable when considering the future in judgment of a resident return and the reproduction of the local industries, etc. JAEA has been carrying out a research project entitled the "Long-Term Assessment of Transport of Radioactive Contaminant in the Environment of Fukushima (F-TRACE Project)", which is concerned re-distribution accompanying radiocaesium transport in the environment of Fukushima and the long-term assessment of radiation dose, since November 2012. This report provides an overview and status of the F-TRACE Project.