Isotopic compositions of ²³⁶U and Pu isotopes in "black substances" collected from roadsides in Fukushima prefecture

Author(s)

Aya Sakaguchi, Peter Steier, Yoshio Takahashi, Masayoshi Yamamoto

Abstract

Black-colored road dusts were collected in high-radiation areas in Fukushima Prefecture. Measurement of ²³⁶U and Pu isotopes and ^134,137Cs in samples was performed to confirm whether refractory elements, such as U and Pu, from the fuel core were discharged and to ascertain the extent of fractionation between volatile and refractory elements. The concentrations of ^134,137Cs in all samples were exceptionally high, ranging from 0.43 to 17.7 MBq/kg, respectively. ^239+240Pu was detected at low levels, ranging from 0.15 to 1.14 Bq/kg, and with high ²³⁸Pu/^239+240Pu activity ratios of 1.64–2.64. ²³⁶U was successfully determined in the range of (0.28 to 6.74) × 10–4 Bq/kg. The observed activity ratios for ²³⁶U/^239+240Pu were in reasonable agreement with those calculated for the fuel core inventories, indicating that trace amounts of U from the fuel cores were released together with Pu isotopes but without large fractionation. The quantities of U and ^239+240Pu emitted to the atmosphere were estimated as 3.9 × 106 Bq (150 g) and 2.3 × 109 Bq (580 mg), respectively. With regard to U, this is the first report to give a quantitative estimation of the amount discharged. Appreciable fractionation between volatile and refractory radionuclides associated with the dispersal/deposition processes with distance from the Fukushima Dai-ichi Nuclear Power Plant was found.

Organisation(s)

Isotope Physics

External organisation(s)

Hiroshima University, Kanazawa University

Journal

Environmental Science & Technology

Volume

48

Pages

3691-3697

No. of pages

7

ISSN

0013-936X

DOI

https://doi.org/10.1021/es405294s

Publication date

04-2014

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics, 103037 Environmental physics

Keywords

ASJC Scopus subject areas

General Chemistry, Environmental Chemistry

Portal url

https://ucrisportal.univie.ac.at/en/publications/2748cfa3-d180-4b10-a3da-cc21f095840b