On Christmas Eve children around the world watch the weather forecast to see where Santa Claus is on his flight around the world. This year, Japanese children will see this image on the left, as they have every evening since last March. This is the radiation data for the Tokyo area broadcast by NHK at the end of the newscast.
Numbers on the black background show natural background levels before the nuclear catastrophe, in microsieverts per hour. Numbers in red font show the readings for the present day.
The numbers look encouraging when you consider that in Fukushima many areas are 10 to 50 times as high, but this map is misleading. The measurement for Chiba prefecture, for example, is taken always in a city in the south that escaped the fallout. In the northwest part of the prefecture, the city of Kashiwa has average levels ten times as high (0.5 microsieverts / hour), with some super hot spots scattered throughout the city where drainage made radionuclides accumulate. In the Narita area in the north, the level is 0.10 ~ 0.20.
In any case, the average external exposure of individuals in the Tokyo area is not much of a concern, even in the hotter zones not indicated by the map, but for those who are concerned, dosimeter badges (showing accumulated dose) are available in local drug stores.
|Dosimeter badges sold in a local drug store in Chiba: about US$50|
The purpose of putting the map up every night is to reassure the public that levels are close to the previous normal background radiation. It is a deceptive reassurance because the true hazards are:
- The internal contamination people are going to get over many years through the food supply, if proper precautions are not taken
- The problem of how to dispose of radioactive debris, incinerator ash, and sewage in which the fallout became highly concentrated
- The risk of another nuclear catastrophe caused by another earthquake - the Japanese nuclear industry is deliberately ignoring the evidence that the earthquake damaged the reactors before the tsunami hit and caused the station blackout. They don't want to consider this because it means the design basis for all nuclear reactors in Japan is built on shaky assumptions.
25 October 2011 | Nature 478, 435-436 (2011) | doi:10.1038/478435a
"The latest analysis also presents evidence that xenon-133 began to vent from Fukushima Daiichi immediately after the quake, and before the tsunami swamped the area. This implies that even without the devastating flood, the earthquake alone was sufficient to cause damage at the plant."