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Chernobyl served as a nuclear power plant,
where during a test in the early hours of April 26, 1986,
an explosion blew the roof off of reactor 4.
Super-heated graphite and huge amounts of 
radioactive particles were released into the air.
Radiation clouds were sent all across the globe.
Thousands of people lived in a town 
called Pripyat near the power plant.
During the catastrophe, two people died immediately, 
while 29 more died within weeks.
Not only this,
It is estimated that thousands more have died from cancers
and other illnesses in the ensuing years.
Vast areas of the country have not seen 
any animal or plant life for over thirty years.
But it does not end there
more than 200 tons of uranium 
is still inside the reactor site,
fueling fears that new radiation leaks 
could occur in the area,
which is already considered to be 
unsafe for at least the next century,
and will remain uninhabitable for the 
next tens of thousand of years, at the best.
So, what was it that makes this accident so catastrophic?
We have seen and read about volcanic eruptions, earthquakes, tsunamis, etc.
which kill thousands of people, 
damage hundreds of houses.
What is it that makes the area uninhabitable 
even after more than 30 years of this accident?
Why can’t the people of Pripyat go back to their city?
The answer is radioactivity.
To understand radioactivity, first we have to understand 
what makes everything around us?
The atoms and their structure!
According to one of the simplest models,
each atom consists of a nucleus in the centre 
containing neutrons and protons.
and electrons revolving around it.
Different types of atoms have different 
number of neutrons, protons and electrons.
which makes them unique.
The defining character of any element is 
the number of protons in the nucleus of its atoms.
Now in most atoms around us, 
this structure is stable.
Which means all particles stay the way they are without changing abruptly.
But in some special cases,
the number of protons and neutrons becomes abrupt and
they just can’t stay together bound up in a nucleus!
and the atom becomes unstable.
Such unstable nuclei lose neutrons and 
protons as they attempt to become stable.
And this process is  accompanied by release of energy.
This release of energy in the form of moving waves or streams of particles is known as radiation.
And the process of an unstable nuclei giving off its particles is called radioactive decay.
Now, what happens to this radiation energy?
Some kinds of radiation (called ionizing radiation) 
can hit other atoms and ionize them, removing electrons.
In the body of humans, or other living things, 
this can break the bonds within the DNA.
It can ruin  the complex structure of proteins. In small doses,
the cell has enough mechanisms to repair itself.
But when exposed to a large amount of radiation,
the cell's defenses are overwhelmed.
And eventually, the cell commits suicide.
The death of a few cells can be tolerated,
but the death of many can lead to necrosis.
Severe radiation exposure can damage or destroy the central nervous system,
and at such levels, the result is a very painful death.
Ionizing radiation can also cause cells to stick 
together improperly, leading to risk of cancer.
But radioactivity can be useful if dealt with care.
Today, radioactivity is used in archaeology (carbon dating), geology, space exploration,
law enforcement etc. as well as for generating electricity.
In the case of chernobyl, just like any other nuclear plant, radioactive materials were used to generate electricity.
How exactly,
a radioactive material gives out energy,
which is used as a fuel to heat water,
creating steam that drives the reactors' turbines and the final
output of energy that we get is converted into electricity.
After the explosion, a huge amount of radioactive matter 
was released in the atmosphere.
Most of the radiation released from the failed nuclear reactor
was from iodine-131, cesium-134 and cesium-137.
Iodine-131 is rapidly ingested through the air 
and tends to concentrate in the thyroid gland.
On the other hand,
Cesium isotopes are the ones that don’t disintegrate rapidly,
but this makes them a matter of concern for years 
after their release into the environment.
If you want to understand in even more depth as to what radiation is,
you have to study all about the atomic structure.
You can do so by downloading our app and watching videos
for Structure of atom, class 9 and atomic structure, class 11.
Click on the link below to download our app.
A committee was created soon after the explosion to see
what was the problem why it happened in the first place.
Chernobyl power plant was soon shut-down too and people were evacuated,
but more pressing question was
what to do now, with all the radioactive matter 
just floating around free in the atmosphere?
Numerous measures have been taken since then 
to control the matter inside the plant perimeter,
including building a confinement area around the
power plant to stop anymore harmful material from leaking.
But the more important question is
what will prevent another chernobyl?
You can read about this more online,
and also about preventive measures 
that we learned from chernobyl.
For more such videos, subscribe to our channel.
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