-- Scientists say that radiation will affect the Chernobyl area
for 48,000 years although it will be safe enough for humans
to begin repopulating the area long before then -- in about
600 years.
—— Chernobyl – a poisoned landscape by Robin McKie 25. 04. 2011
—— 科学家们说辐射对切尔诺贝利地区的影响将持续
4.8万年之久，尽管人们在此很早之前就可以开始在该
地区居住——大约600年后。
Affects Will Last 300 Years
The 200 tons of hardened nuclear fuel and debris remains so radioactive that even today scientists cannot approach it. Some radioactive elements in nuclear fuel decay quickly; however,
cesium has a half-life of 30 years, and strontium has a half-life
of 29 years. According to scientific estimates, it takes 10 to 13
half-lives before economic activity and life can return to a contaminated area.
This means that the total area contaminated by the Chernobyl disaster — 15,000 square miles — will be affected for the next 300 years.
—— Chernobyl Before and After the Worst
Nuclear Disaster in History More than 25
years after the nuclear disaster, the word
Chernobyl still incites fear and concern
Radiation will stay in the Chernobyl area for the next
48,000 years but humans may begin repopulating the
area in the next 600 years or so. The experts predict
that by than the most dangerous levels of radiation
will have disappeared or been sufficiently diluted into
While they work on the same principles, the detonation
of an atomic bomb and the meltdown of a nuclear plant
are two very different processes.
An atomic bomb is based on the idea of releasing as
much energy from a runaway nuclear fission reaction
as possible in the shortest amount of time. The idea
being to create as much devastating damage as
possible immediately so as to nullify enemy forces
or intimidate the opposing side into surrender. Both
effectively ensuring the conflict ends quickly. Thus,
it would be important that the area bombed does not
remain uninhabitable long after the two sides make
peace (Ok, that's my own speculation, but I think it's
a niceideal to work with).
A nuclear reactor is based on the idea of producing
low amounts of power using a controlled and
sustained nuclear fission reaction. The point being
that it does not release all of the energy at once and
slower reaction processes are used to ensure
maximum lifetime of the nuclear fuel.
Moving beyond the ideas behind each, the radioactive isotopes created in an atomic blast are relatively
short-lived due to the nature of the blast and the fact
that they are normally detonated above the ground
to increase destructive power of the concussive
wave. Most radioactive materials from an atomic
blast have a maximum half-life of 50 years.
However, in the Chernobyl meltdown, most of the
actual exploding was due to containment failure
and explosions from steam build-up. Chunks of
fuel rods and irradiated graphite rods remained
intact. Furthermore, the reaction has, both initially
and over its life, produced a far higher amount of
radioactive materials. This is partly due to the
nature of the reaction, the existence of intact fuel
to this date, and that the explosion happened at
ground level. A fission explosion at ground level
creates more radioactive isotopes due to neutron
activation in soil. Furthermore, the half-lives of
the isotopes made in the Chernobyl accident
(because of the nature of the process) are considerably
longer. It is estimated that the area will not be habitable
for humans for another 20 000 years (Edit: to prevent
further debate I rechecked this number. That is the
time before the area within the cement sarcophagus
- the exact location of the blast - becomes safe. The
surrounding area varies between 20 years and
several hundred due to uneven contamination).
Long story short, an atomic bomb is, like other bombs, designed to achieve the most destructive force possible over a short amount of time. The reaction process that accomplishes this ends up creating short-lived radioactive particles, which means the initial radiation burst is extremely high but falls off rapidly. Whereas a nuclear reactor is designed to utilize the full extent of fission in producing power from a slow, sustained reaction process. This reaction results in the creation of nuclear waste materials that are relatively long-lived, which means that the initial radiation burst from a meltdown may be much lower than that of a bomb, but it lasts much longer.
In the global perspective: an atomic bomb may be hazardous to the health of those nearby, but a meltdown spreads radiation across the planet for years. At this point, everyone on Earth has averaged an extra 21 days of background radiation exposure per person due to Chernobyl. This is one of the reasons Chernobyl was a level 7 nuclear event.
All of this contribute to why even though Hiroshima had an atomic bomb detonate, it is Chernobyl (and Fukushima too I'll wager) that remains uninhabitable.
