Jose is likely wrong. Even if the worst possible contamination happens,
all life on earth will not cease next year, much less in the near
future. Insects, bacteria, and some other life-forms are incredibly
more resistant to the effects of ionizing radiation than are the higher
life forms. That being said, studies of survivors of Hiroshima and
Nagasaki showed a surprisingly and unexpected low incidence of birth
defects and sterilization. The greatest risk seems to be an elevated
incidence of cancers, primarily among the survivors (who did not
continue to be contaminated after a relatively short period of time) and
a lesser increase in cancers than the norm among their offspring.
Therefore, total meltdowns with long-term, wide spread, impossible to
clean-up contamination will cause a very real threat to the continuation
of our life expectancy (and that of higher life-forms) for a very long
time into the future, but probably not eradicate any species.
The total amount of extremely radioactive, uncontrolled, very hot, spent
reactor fuel in the 4 badly damaged pools in the reactor buildings plus
the 3 badly damaged reactor cores is huge. Each spent fuel pool is
probably holding the equivalent of at least 4 fully loaded reactor cores
and that spent irradiated fuel is much more radioactive and dangerous if
released than the fuel inside each of the 3 damaged cores.
The power plant is essentially on a beach. A full fuel melt down through
the bottom of the plant of any of these 7 collections of out of control
fuel rods will put multi-thousand degree molten, incredibly radioactive
material in direct contact with the pacific ocean once the fuel burns
through the sand (the temperature is high enough to fully and easily
liquefy sand). The resulting steam explosion is likely to disperse far
more radioactivity than multiple Chernobyls.
The big problem is not I-131. The half-life of that isotope is only 8
days, and uptake can be blocked by appropriate use of potassium iodide
until environmental levels return to a safe level. A much larger
problem is Cesium-137, which has a half-life of 30 years, is water
soluble and therefore taken up by all the plants and animals in our
Also released will be Strontium-90, which behaves like calcium and is
taken up into the bones and teeth and has a half-life of almost 29 years.
Plutonium isotopes are released, which decay into several much more
dangerous isotopes of Americium, one of which has a half life of 7,370
years. This stuff is an alpha particle emitter, which is almost
harmless when outside the body but is highly carcinogenic from the inside.
If this incredibly radioactive brew comes into direct contact with the
Pacific Ocean, it will be easily and relatively rapidly spread
throughout the world. Although the dilution factor will be tremendous,
the total amount of very long-lived radioactive matter will also be
tremendous. There is no way to predict how many of the 7 at-risk
collections may go to full melt-down, but if even a few do, the
world-wide consequences could be huge for tens of thousands of years.
It will not be Armageddon, but will probably be the worst disaster the
planet has endured since the great meteor crash approx. 65 million years