Animations of dispersion simulations of the Fukushima Accident

Research Group for Environmental Science has released results of analysis on the environmental transport of radioactive materials discharged to the atmosphere and ocean from the TEPCO's Fukushima Daiichi Nuclear Power Plant by using the computer simulation system: SPEEDI-MP (SPEEDI Multi-model Package) developed by the group. Here, animations created from these simulation results are presented.
It should be noted that these results are computer simulations based on the preliminary estimated source term and some assumptions and do not guarantee the actual distributions of radioactive materials and radiation doses. However, these results will provide helpful information to understand the condition of distributions of radioactive materials and radiological doses.


1. News release of JAEA (2011.6.13): Analysis on the dose rising process on 15 and 16 March

JAEA analyzed the dose rising process on 15 and 16 March, when a large amount of radioactive materials are estimated to have been released from the TEPCO's Fukushima Daiichi Nuclear Power Plant. See more detailed information here.

Dose rising process at the northwest direction from the plant: Distributions of air dose rate, rain intensity, and concentration of I-131 accumulated in vertical air column (2-D animations)


2. Research paper: Numerical reconstruction of high dose rate zones due to the Fukushima Daiichi Nuclear Power Plant accident

Concerning the above news release, further analysis have been carried out and the results are presented in the paper. This paper is published on the following Web page of the Journal.
Katata et al., Journal of Environmental Radioactivity (2011)

Dose rising process at the northwest direction from the plant (3-D animations): View from directly above (MPEG: about 13MB), View from south-east derection (MPEG: aout 13MB)


3. Technical description of JAEA (2011.6.15): Estimation of cumulative exposed doses of all over Japan for two months

JAEA estimated provisionally cumulative exposed doses of all over Japan for two months since the occurrence of the accident at the TEPCO's Fukushima Daiichi Nuclear Power Plant using WSPEEDI (Worldwide version of SPEEDI). See more detailed information here.

Preliminary estimation of external effective dose for two months after the accident (2-D animation): AVI format (about 119MB), WMV format (about 6MB)

Preliminary estimation of internal effective dose of I-131 for two months after the accident (2-D animation): AVI format (about 123MB), WMV format (about 6MB)


4. Report to the Japan Atomic Energy Commission, etc. (2011.9.6, etc.): Analysis on dispersion and surface deposition of I-131 and Cs-137 over Eastern Japan by WSPEEDI

WSPEEDI analysis on dispersion and surface deposition of I-131 and Cs-137 over Eastern Japan until the end of April was carried out, and the results were provided to the Ministry of Health, Labour and Welfare (news release on 31 Aug., Ibaraki Prefecture on 2 Sep.), and the Japan Atomic Energy Commission on 6 Sep. Especially, the report to the Japan Atomic Energy Commission includes the analysis on daily fall out as well as total deposition of Cs-137 until the end of April.

Dispersion and surface deposition of I-131 over Eastern Japan (2-D animation)
Dispersion and surface deposition of Cs-137 over Eastern Japan (2-D animation)
Dispersion and surface deposition of I-131 over Eastern Japan (3-D animation)
Dispersion and surface deposition of Cs-137 over Eastern Japan (3-D animation)


5. Research paper (2011.11.1): Preliminary Numerical Experiments on Oceanic Dispersion of 131I and 137Cs Discharged into the Ocean because of the Fukushima Daiichi Nuclear Power Plant Disaster

The amounts of radioactive materials discharged to the ocean from TEPCO's Fukushima Daiichi Nuclear Power Plant were preliminary estimated, and analysis on the oceanic dispersion of radioactive materials was carried out by using output from WSPEEDI as input for sea surface deposition as well as the direct discharge from the plant. This paper is published on the following Web page of the Journal.
Kawamura et al., Journal of Nuclear Science and Technology, Vol.48, No.11, p.1349-1356 (2011)

Sea surface concentration of I-131: Simulation from 12 March to 30 April (2-D animation)
Sea surface concentration of Cs-137: Simulation from 12 March to 28 April (2-D animation)


6. Presentation at 2013 Annual Meeting of Atomic Energy Society of Japan (2013.3.27): Analysis on dispersion and surface deposition of Cs-137 over Eastern Japan

WSPEEDI analysis on dispersion and surface deposition of Cs-137 over Eastern Japan has been improved by modification of deposition calculation scheme, better reproducing Cs-137 deposition pattern of airborne monitoring by MEXT.

Dispersion and surface deposition of Cs-137 over Eastern Japan (2-D animation), WMV format (about 3MB)


7. Research paper (2019.12.16): Reconstruction of atmospheric release and spatiotemporal distribution of radioactive materials

Using new monitoring data and the analysis method based on Bayesian inference, JAEA optimized source term of radioactive materials released into the atmosphere and construct the database of spatiotemporal distribution in the air and ground surface.
The results are presented in the paper: Terada et al., Journal of Environmental Radioactivity (2020). See more information here.

Dispersion and surface deposition of Cs-137 (2-D animation)


8. Research paper (2021.7.26): Analysis results of atmospheric air concentrations and deposition of Cs-137 in the Northern Hemisphere and sea surface concentrations of Cs-137 in the North Pacific

We conducted the atmospheric dispersion simulation of Cs-137 in the Northern Hemisphere and oceanic dipsersion simulation of Cs-137 in the North Pacific to validate the atmospheric release information.
The results are presented in the paper: Kadowaki et al., Journal of Environmental Radioactivity (2021)

Atmospheric dispersion and deposition of Cs-137 in the Northern Hemisphere (2-D animation)
Oceanic dispersion of Cs-137 in the North Pacific (2-D animation)