Understanding radiation in Tokyo as a consequence of the Fukushima nuclear disaster
Sources of radiation information and analysis as of 18 March 2011
On Friday March 11, at 14:46 one of the world’s largest earthquakes ever happened close to Japan’s coast near Fukushima, triggering a series of disasters which are still ongoing, and which brought much suffering. Human suffering continues, after-quakes continue – for a full week we had 20 or more after-quakes every day, some also quite strong, including several during the production of this newsletter. Understanding radiation in Tokyo has become a key factor for decision making by government, companies and population
We will interview one of the world’s most important earthquake experts in one of our next newsletter.
In this edition we focus on the radiation issues from the nuclear power station disaster
For an assessment of the situation at the Fukushima nuclear power stations, you may be interested to read a report of March 15, 2011 by the UK Government’s Chief Scientific Officer Professor John Beddington.
Our understanding of Japan’s radiation situation
Japan’s Government AIST laboratory (which is METI’s largest laboratory and it’s competence and R&D results are very respected for a long time) is publishing radiation measurements taken in their Tsukuba laboratory directly, and include analysis of the radiation (Tsukuba is in Ibaraki-ken north of Tokyo in direction of the Fukushima nuclear power station – so we expect radiation in Tsukuba to be higher than in Tokyo) – you can find them here: http://www.aist.go.jp/taisaku/ja/measurement/index.html
Japan’s Science and Education Ministry publishes radiation data for the last 24 hours for all of Japan here: http://atmc.jp/
Radiation data for Tokyo/Shinjuku are published here
Our short analysis of the radiation data for Tsukuba and Shinjuku
Sv, Sievert, uSievert refer to the impact on the body by radiation, not to the physics of the radiation itself, which is measured with different units. find details here: http://en.wikipedia.org/wiki/Sievert
You can see that in Tsukuba the radiation impact on humans is currently on the order of 0.08 – 0.10 micro-Sieverts/hour.
The radiation measurements in Tokyo-Shinjuku show around 0.05 micro-Sieverts/hour
This means that the radiation levels in Tsukuba are currently the same as you would typically experience in Austria, while the radiation levels in Tokyo-Shinjuku currently are about 30% lower than the lowest radiation levels in Austria, and about 4 times lower than the highest radiation levels in Austria. We have made similar comparisons for Italy.
We conclude that currently radiation levels in the Tokyo region are of similar magnitude or lower than in typical European countries.
Regarding radiation, please note also that radiation is not equal radiation, there are
- alpha (= Helium nuclei),
- beta (= electrons e.g. inside vacumm TV tubes and old fashioned PC terminals) and
- gamma rays (= high energy X-rays),
- and other types or radiation (e.g. neutrinos).
When people talk about “radiation” from the Nuclear power station, they don’t usually mean the direct alpha, beta, gamma radiation or neutrons, which cannot travel far, but they mean radioactive ions. The harmful nature of radio-active ions depends very much on what kind of ions these are, and specially also their half-life, and whether they are attached externally to clothing or shoes, or whether they are inhaled or eaten and remain in the body. Some decay very fast, and others live very long. Some, like plutonium are also very poisonous in addition to radioactivity.
Further information on radiation levels in Japan
It turns out that according to an article in NATURE, the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is collecting and transmitting very details data on radioactivity and composition of radio-nucleides in and around Japan, but it keeping these data secret.
We do not know the reasons why it is necessary to keep CTBTO’s measured data about radiation in Japan secret during this disaster. If anybody reads this newsletter familar with CTBTO’s conditions – maybe this person could urge the publication of these radiation data.