Geochemical Journal, Vol. 46 (No. 4), pp. 335-339, 2012
Sebastian O. Danielache,1 Chisato Yoshikawa,2 Antra Priyadarshi,3 Toshihiko Takemura,4 Yuichiro Ueno,1 Mark H. Thiemens3 and Naohiro Yoshida1
1Department of Earth and Planetary Science, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
2Department of Environmental Science and Technology, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
39500 Gilman Drive, University of California San Diego, La Jolla, California 92093, U.S.A.
4Research Institute for Applied Mechanics, Kyushu University, Fukuoka 816-8560, Japan
(Received February 29, 2012; Accepted June 3, 2012)
We present a numerical study carried out with the SPRINTARS model modified to account for the radioactive decay of 35S compounds emitted from the Fukushima Daiichi nuclear power plant station after the hydrogen and vapor blast. The transport dynamics of the released material reproduced previous field observations. Four different emission scenarios were compared to the measurements of atmospheric 35S in sulfate collected in La Jolla, Tsukuba, Kashiwa and Yokohama. Linear regressions of the relation between emitted and transported material that reached the sampling sites were used to estimate the amount of 35S atoms and the amount of neutrons released in to the atmosphere. We estimate that a lower limit of 1.9 × 1016 35S atoms sec-1 were released after the events in March and this flux dropped to 4-39 × 1014 35S atoms sec-1 at the end of the month. Based on this calculations we estimated a lower limit of 5.2 × 1021 slow neutrons m-2 sec-1 were emitted from the nuclear fuel rods to the sea water injected in the reactors after the events in March.
Key words: Fukushima Daiichi nuclear power plant, radioactive isotopes, sulfate, global transport model, SPRINTARS