Where can you find compiled data on radiation and Fukushima?


Everyday, TEPCO and the ministries issue tables of data of the Fukushima Daiichi plant and the radiation levels in environment and food products everyday. However, those tables contain an overwhelming number of figures in different units, and are just hard to comprehend for a layperson like myself. How can we organize them, and what should we look for in that data? (50s Tokyo)


With the situation of the Fukushima Daiichi power plant remaining very serious, it is best to keep ourselves updated on how much radiation is emitted and what is going to happen at Fukushima, so we can act properly and promptly when necessary. Raw data is a challenge to understand for everybody, so let’s forget about it and instead, focus on more accessible graphs and summaries produced by volunteer researchers and computer scientists.

First, let us look at radiation levels in the air. Prof. Ryugo Hayano of the University of Tokyo has been updating measurements of radiation levels in affected cities every day since March 15. For example, the figure below shows the radiation levels in each city from March 15 to April 3.

May 2 – Present: Updated daily

Note that there is a large leap in the radiation levels of most cities on March 16. This leap shows that radioactive substances from the Fukushima Daiichi plant arrived at those cities on that day, carried by winds after the hydrogen explosions on March 15. Following the jump is a decrease of the radiation levels, due to the relatively short lifetime of the radioactive iodine contained in large amount.

Another leap on March 21 is due to the rain. Radioactive substances that remained high in the sky after the hydrogen explosions came down with the rain, and the radiation level at the ground took a leap again. The level also subsides with time, which implies that there has not been a massive leak of radioactive substances at Fukushima after the hydrogen explosions. It should help you better understand what is going on in the air by simply remembering the trend—radiation levels shoots up with a massive leak and then, gradually decreases.

Second, it is important to monitor radiation levels in water and foods. Here we recommend a fully automated, multi-lingual website by satoru.net. Radiation levels in water in every city and tested food products are listed there, and are automatically updated as soon as the data is available. Just make sure that you select your language in the pull-down menu, and it will automatically machine-translate each word for you.

Finally, monitoring the situation at each Fukushima Daiichi nuclear power plant is a key to understanding the future. Here, too, we recommend auto-update plots by satoru.net. In order to keep the fuel rods’ heat contained, the entire rods must be submersed in cooling water, and in order to keep the water at safe level (https://atmc.jp/), the pressure inside the reactor must be kept low for continued water injection. If this cycle breaks down, the fuel rods become exposed and the heat melts the rods.

An excellent source of detailed Fukushima status summary is on Wikipedia (click “Show”). For a more official source, look for reactor summary on the IAEA’s presentations list.

Science Communicator: Misato Hayashida

The amount of radiation
The amount of iodine-131 in tap water
Events at the Fukushima Daiichi
The timeline of the Fukushima Daiichi