Concerning the questions about radiation rising into the atmosphere.

Radiation itself is a form of light-wave, or of elementary particles which extend out similar to how light behaves. The radiation itself does not rise in the atmosphere any more than light extends out in all directions in a particular moment.

Radiation is produced at random moments by "radioactive particles". Radiation is produced mostly by material, in this case of Fukushima, and much of that pollution is in the form of fine particles down to the molecular level.

As a different example, radiation produced by a microwave oven is not produced by matter, so when the electromagnetic emitter is turned of, just like a lamp is turned off, that radiation ceases to exist.

The radiation measured by a dosimeter is measuring the "light", the radiation itself, but does not easily or simply describe the true risk to life, which is better described in the composition and distribution of the dust which is the source of the radiation, and where that material will tend to concentrate.

When those radioactive particles rise into the atmosphere in the form of fine dust, then the carriers of the future radiation to be produced by that material, that is what rises up into the atmosphere.

Radioactive exposure from material sources is very problematic, because it continues for very long periods of time.

The Fukushima situation is very Fucked.

This is why, if higher life forms wish to survive on this planet, then those open sores need to be capped with boron and concrete.

This is because it is easier to deal with the radiation itself in the form of "light", by building solid barriers, than to deal with the radioactive materials which continue to emit the radiation, once they are let loose into the environment.