Deposition of fission and activation products after the Fukushima Dai-ichi nuclear power plant accident

The Great Eastern Japan Earthquake on March 11, 2011, damaged reactor cooling systems at Fukushima Dai-ichi nuclear power plant. The subsequent venting operation and hydrogen explosion resulted in a large radioactive nuclide emission from reactor containers into the environment. Here, we collected environmental samples such as soil, plant species, and water on April 10, 2011, in front of the power plant main gate as well as 35 km away in litate village, and observed gamma-rays with a Ge(Li) semiconductor detector. We observed activation products (Np-239 and Fe-59) and fission products (I-131, Cs-134 (Cs-133), (CS)-C-137, Ag-110m (Ag-109), Te-132, I-132, La-140, La-140, Sr-91, Y-91, Zr-95, and Nb-95). Np-239 is the parent nuclide of Pu-239; Fe-59 are presumably activation products of Fe-58 obtained by corrosion of cooling pipes. The results show that these activation and fission products, diffused within a month of the accident. (C) 2012 Elsevier Ltd. All rights reserved.