posted on Dec, 28 2015 @ 11:36 AM
Volatility is not a simple subject. In the case of Chinese Coal, it is the combustion products that allow small particulate matter to rise high into
the atmosphere, once there it is more susceptible to the flow of the wind before falling back to Earth. You have to get it up there though. And in the
case of coal burning, we are talking tonnes of material, and it is only coming down as a trace of material that slowly deposits with time.
In Fukushima, the amount of material is much lower so thats a bit better,
On Iodine 131, it has an 8 day half life, in physics we typically say to reduce the half life to an undetectable/non-useful level we need to wait for
10 half lives, which is around 80 days. This is why the Iodine contaminated cat litter needs to sit for 3 months... BUT to be honest after only 40
days the levels will be abut 3% of what it was at the beginning.
It beta decays into an excited state of Xenon which then Gamma decays to its ground state.
Iodine 129 is much longer lived, but has a much lower production yield than 131. Half life is about 15million years so, that stuff will just float
Radioactive particles do theoretically give of heat, because heat is energy, but it is not as simple as saying oh the dust is radioactive and thus hot
and such will rise. In fact much of the heavy isotopes like to plate out on things, Uranium decay chain products (which are almost the same for U238
and U235) will tend to plate out by the time they get to lead and polonium meaning they will no longer be highly mobile, the mobile breed really is
only around for a half life of about 11 days.
The reason i say they don't put themselves into the atmosphere is because the energy of each decay itself is quite small, and the only way to generate
lots of heat is to have it contentrated. now in a reactor it is exactly that... but... heat is lost to the environment quite quickly. You will get a
plumb but, it wont be driven by the radiation in most cases. It will be driven by a pressure shock more than anything else i think... unless you have
actual big chunks of material flying everywhere (Which, in Fukushima, no primary chunks of material did fly anywhere) Most of the long term issues are
from leakages of the cooling systems into the ground, or the loss of containment on the radioactive slag as it cools off.
by comparison to Chernobyl, the event released about 1/5 of the radioactive material, the main reason is simply due to the fact the reactor was
enclosed by pressure vessels structurally.
The bad stuff is Caesium which hangs about for a few million years, this is only detected in trace levels.
It is great cause for concern yes, but nothing like as bad as say... the nuclear bomb tests America did in the atmosphere through the 50s and 60s,
which seeded a large area with lovely radioactive isotopes.
The proof is also in the testing of materials and the air. I remember posts here claiming "OMG background levels went up by a factor of 2 after it
rains" which is perfectly normal with or without a nuclear disaster... not to mention that the natural radioactive background can change by a factor
of about 1000 across the whole surface of the Earth (depending where you are, huge hotspots removed) I mean... no one worries too much for example
that most smelting plants that extract Iron and Nickel usually have big slag piles that are extremely radioactive compared to background levels... but
thats fine... because we never think about it...