Radiation back ground level was 0.036 μSv/h in Tokyo before 311

According to Ministry of Education, Culture, Sports, Science and Technology, the radiation level (gamma ray) in Tokyo was 0.036 μSv/h before 311.

This was the reference materials of the geiger counter that MEXT used to rent for educational purpose for free. Now they rent it only to schools and educational organizations.

The individuals who rent the geiger counter from MEXT measured radiation level from 1990 to 1998 and the readings were recorded on the map below.

Radiation levels in Japan before 311The note says, “The ground of western Japan contains more granite. On the other hand, the ground of eastern Japan contains Kanto loam formation, which is less radioactive. The radiation level therefore is higher in western Japan.”

Source 1 2 3



Français :

La radioactivité naturelle était de 0,036 μSv/h à Tokyo avant le 11 mars 2011

Selon le ministère de l’Éducation, de la Culture, des Sports, de la Science et des Technologies (=MEXT), le niveau de radioactivité (gamma) de Tokyo était de 0,036 μSv/h avant le 11-3.

C’était établi sur les données de référence acquises par les compteurs Geiger que le MEXT avait l’habitude de prêter gratuitement pour usage éducatif. A présent ils ne les prêtent qu’aux écoles et aux organisations scolaires.

Les gens qui ont emprunté un compteur Geiger au MEXT ont relevé le niveau de radioactivité entre 1990 et 1998 et leurs résultats ont été synthétisés dans la carte ci-dessous :

Radioactivité naturelle du Japon avant le 11 mars 2011La  note dit : “Le sol de l’ouest japonais est plus granitique. D’un autre côté, le sol de l’Est japonais contient les formations terrigènes de Kanto qui sont moins radioactives. Le niveau de radioactivité est donc plus haut dans l’Ouest japonais”.

Sources : 1 2 3

About this site

This website updates the latest news about the Fukushima nuclear plant and also archives the past news from 2011. Because it's always updated and added live, articles, categories and the tags are not necessarily fitted in the latest format.
I am the writer of this website. About page remains in 2014. This is because my memory about 311 was clearer than now, 2023, and I think it can have a historical value. Now I'm living in Romania with 3 cats as an independent data scientist.
Actually, nothing has progressed in the plant since 2011. We still don't even know what is going on inside. They must keep cooling the crippled reactors by water, but additionally groundwater keeps flowing into the reactor buildings from the broken parts. This is why highly contaminated water is always produced more than it can circulate. Tepco is planning to officially discharge this water to the Pacific but Tritium is still remaining in it. They dilute this with seawater so that it is legally safe, but scientifically the same amount of radioactive tritium is contained. They say it is safe to discharge, but none of them have drunk it.


December 2012