2020 Fall Meeting

Presentation information

Oral presentation

V. Nuclear Fuel Cycle and Nuclear Materials » 505-3 Decommissioning Technology of Nuclear Facilities

[3D07-10] Evaluation of Contamination Distribution

Fri. Sep 18, 2020 2:45 PM - 4:00 PM Room D (Zoom room 4)

Chair:Kazuya Idemitsu(Kyushu Univ.)

3:15 PM - 3:30 PM

[3D09] Development of dose evaluation method for confirmation of completion of decommissioning

(2)Identification of radiocesium origin using 135Cs/137Cs isotope ratio

*Asako Fujiwara Shimada1, Takehiko Tsukahara2, Masao Nomura2, Min Soek Kim2, Taro Shimada1, Seiji Takeda1, Tetsuji Yamaguchi1 (1. JAEA, 2. Tokyo Tech)

Keywords:135Cs/137Cs isotope ratio, identification of origin, decommissioning, accident at the Fukushima Daiichi Nuclear Power Station

Radiocesium from the Fukushima Daiichi Nuclear Power Station (1F) accident can be treated as background radioactivity at completion of decommissioning, so determining the origin of radiocesium is essential. Therefore, we studied identification of radiocesium origin using 135Cs/137Cs isotope ratio. The ratio originated from 1F was 0.3628±0.0005. When the ratio originated from decommissioning facility was 0.05-0.2 larger than that originated from 1F, it is challenging to decrease the stand deviation less than 0.01 for 1 Bq/g of 137Cs because precision was decreased as decreasing the 137Cs concentration. If the ratio is able to be determined within the standard deviation of 0.0005 for 0.5 Bq/g of soil sample, the identification would be available.