[M-AG34] [EJ] Dynamics of radionuclides emitted from Fukuchima Dai-ichi Nuclear Power Plant in the environment

[MAG34-07] Investigation of soil radionuclude near the Fukushima Dai-ichi Nuclear Power Plant 5-year after the accident by JpGU-JNRS team

*Kazuyuki Kita¹, Atsushi Sinohara², Kencho Kawatsu³, Kazuhiko Ninomiya², Yuki Inai², Haruka Minowa⁴, Tsutomu Ohtuki⁵, Yasushi Kino⁶, Kazuma Koarai⁶, Takashi Saito⁷, Yukihiko Sato⁸, Keisuke Sueki⁹, Koichi Takamiya⁵, Yukio Takeuchi¹⁰, Taeko Doi¹⁰, Yoshinari Abe¹¹, Yasuhiro Iwamoto¹², Masaki Uesugi¹³, Satoru Endou¹⁴, Hiroshi Okochi¹², Naoya Katsumi¹², Akimitsu Kanda², Kenya Kubo¹⁵, Yuya Koike¹⁶, Akinori Sueoka¹², Anna Suzuki², Masatoshi Suzuki⁶, Kenji Suzuki³, Tsugiko Takase³, Masaomi Takahashi², Zi Jian Zhang², Izumi Nakai¹¹, Seiya Nagao¹³, Akihiro Nanbu², Fujita Nobuhumi², Yuichi Moriguchi¹⁸, Akiyo Yatagai¹⁷, Akihiko Yokoyama¹³, Go Yoshida², Takashi Yoshimura², Akira Watanabe³ (1.Ibaraki University, 2.Osaka University, 3.Fukushima University, 4.The Jikei University School of Medercine, 5.Kyoto University, 6.Tohoku University, 7.Shokei Gakuin Daigaku, 8.Japan Atomic Energy Agency, 9.Tsukuba University, 10.National Institute of Environmental Studies, 11.Tokyo University of Science, 12.Waseda University, 13.Kanazawa University, 14.Hiroshima University, 15.International Christian University, 16.Meiji University, 17.Hirosaki University, 18.University of Tokyo)

Keywords:Fukushima Dai-ichi Nuclear Power Plant, Radiocesium, soil deposition density

[Introduction] A large-scale soil sampling project for radionuclides from the Fukushima Dai-ichi Nuclear Power Plant accident was conducted in June 2011 by a research group including the Japan Geoscience Union (JpGU) and the Japan Society of Nuclear and Radiochemical Sciences (JNRS). New research project following the 2011 project was also implemented by JpGU-JNRS team with the objective to know the transition process of radioactive cesium in soil and the current contamination in 2016 when five years passed since the accident.
In this report, the outline of the project will be presented. We will also present some preliminary results of the inventory of 134Cs and 137Cs in the soil, comparing 2011 and 2016. More detailed results wll be presented in another report.

[Sampling and Measurement] Between June and September 2016, 176 researcher of total had worked to measure the air dose rate and collect soil samples at 105 locations near the Fukushima Dai-ichi nuclear power plant, mainly on the difficult-to-return zone, for 9 days in total. Surface soil was sampled at 5 points per one location as well as air dose rate at 5 cm and 1 m from the ground surface. The sample from depths of 5 cm was divided into two parts of 0 - 2.5 cm depth and 2.5 - 5 cm depth, filled in a U-8 container after drying. Radiocesium was quantified using gamma ray spectrometry with Ge detectors. To understand the transion of radiocesium in soil, 30-cm depth soil core samples were obtained at about 1/4 of all locations.