World Eyes Japan's Nuclear Crisis
[UPDATE 3/21] Heroic efforts are being made to contain the damage, but radiation levels at the reactors have reached the highest levels, putting workers at risk. Leaked water samples had radiactivity levels 100,000 times normal levels. It may take several months to bring the reactors back to normal
Like a recurring nightmare, Japan is once again at the center of a possible nuclear disaster. The country is all too familiar with the effects of nuclear radiation after the bombing of Hiroshima and Nagasaki that ended World War II. Now, the twin earthquake and tsunami that struck the country last week have unleashed another threat -- the possibility of a nuclear meltdown.
Fires and explosions rocked four of the six reactors, leading Japan to evacuate people within a 12 mile (20 kilometer) area. Japan has been scrambling to restore electricity to cool the radioactive material in the nuclear reactors.
What caused the nuclear reactors to fail and what does a meltdown mean? Lets take a step back at how a normal reactor works.
Fission, a chain reaction
Over the past few decades, nuclear energy has emerged as a replacement for non-renewable sources such as coal and oil. At the heart of the reactor is a large vessel that contains radioactive rods made of Uranium 235, an isotope of Uranium -- isotopes are different flavors of the element, each with a different number of neutrons.
This Uranium isotope has a special property and can undergo a chain reaction called nuclear fission. That is, its atom can be made to split, and the free neutrons that are released from the nucleus bombard other Uranium atoms causing them to split and so on. Splitting of the atom releases a tremendous amount of energy in the form of heat and radiation. This heat energy converts water to steam, causing a turbine to rotate and generate electricity.
The amount of energy generated by fission is millions of times greater than that from an equivalent amount of fuel such as gasoline! Hence, fission has to be done in a controlled way -- the Uranium rods are kept immersed in water to keep them cool, special control rods are inserted to absorb the free neutrons and slow down the fission, and the entire unit has to be enclosed in a steel containment vessel to prevent radiation from leaking.
What went wrong in Fukushima?
When the earthquake struck, three of the reactors that were working were immediately shut off. However the intense heat and radiation that is generated inside requires water for cooling. Unfortunately, the pumps to circulate water and generators for backup electricity stopped working.
Then came the explosions -- one theory is that increased radiation caused water molecules (H2O) to split into Hydrogen and Oxygen. The build-up of hydrogen gas is believed to have caused the explosion which ripped the outer concrete walls. The extent of damage to the inner containment vessel is not clear.
Japanese authorities have been spraying water using helicopters and meanwhile, working hard to restore electricity. Without cooling, the Uranium rods could melt down, releasing high levels of radioactive materials into the atmosphere. At the time of writing, two of the six reactors are under control.
How much is too much?
Many ordinary heroes have emerged in Japan -- people who have put their lives at risk to protect their countrymen. Normally, people are exposed to 3-6 millisieverts (unit of measurement) of radiation a year, but workers at the plant have been exposed to 100-150 mS. Too much radiation can cause hair loss, cancer and in the worst case, death. You may have seen people on television wearing suits and using special Geiger counters to check radiation levels on people leaving the area.
You know President Obama recommended that they all stay a 50 mile radius. But Japan's leaders are only saying a mile. Someone people could get radition and then it could become like that place in Russia where everyone around became sick and in the end the whole area had raditation.
I`m Japanese. I wasn`t there at the earthquake but I really hope that there won`t be a nuclear meltdown. The people are actually more afraid of another giant earthquake.
wow dang i can't believe that this happened. ya actually a boy in my school is Japanese he is a new student so i think they moved here from there because he has to use a translator to be able to under stand.
And i thought that the earthquake in Haiti was bad... :(
so many problem happened this year
i feel very bad for japan. many have (obviously) died and i feel so sorry for them, including the animals. :(
my sewing class is planning on making some stuff and selling it to raise money to help japan
the american red cross foundation asked my school if we could also help them with the earthquake.
our school is raising money for the japanese earthquake and the nuclear disaster.
geez, i hope nothing bad happens.... i want japan nice for when i get there!
i feel sorry, tho, for everyone there... *sniff*
This is really scary and it's so sad!
japan has had the tsunami and this nuclear meltdown , it seems like they would have a world record of the things that have been very severe.
So what, if the radiation didn't hit us, it might.
You'll never be sure.
they have certain equipment that can tell them how much radiation is in the air, and where it is. so we will know if the radiation gets as far as the US.
I'm pretty sure that the situation is under control, our principal told me most of the cooling systems had been repaired.
Also, doesn't nuclear fusion provide the same energy as fission except it's much less dangerous?
Nuclear fusion liberates much more energy than nuclear fission. At least, nuclear fission can be controlled and regulated in a nuclear reactor.
Scientists have been trying to harness nuclear fusion from the very beginning, but it is a really difficult process. Nuclear fusion is more dangerous than nuclear fission. This could be understood by looking at the reactions taking place in the sun (Hydrogen combining with other hydrogen atoms to form Helium).
i can,t believe that japan has so many problems and it is such a small country will it vanish?
i feel so bad that it will destroy the earth
Japan is having a very bad week very very very sad
Japan has managed this crisis well.
I wonder why nuclear reactors were set up when Japanese government knew that Japan is an earthquake prone area?
Because Japan is highly populated for it's size...
It can't get all it's energy by fuel or oil.
It is driven by energy demand. Japan gets 30% of its electricity from nuclear energy. It has thermal and hydroelectric plants but that is not enough to meet the needs of its growing population and industries. It is unfortunate for Japan that it is a small country and situated in an earthquake prone area.
I have a friend in Japan, and our school is raising money to help Japan
They have been able to put a stop on most of the radiation in Japan, but some is still contaminating the products.
sooo.. sad i felt so bad for japanese people..
that radiation is really bad.. it would be awful to wear those white masks all the time. good thing that radiation is not really going to hit the united states. The tsunami is bad enough as it killed a lot of people.
i saw on channel one news that they had to check people to see if they had radiation in them. They had to search the car they drove over there.. it must have been awful to be there at the moment.
its too bad that so many families and family members were lost
i feel really bad for japan.
i would love to help japan i am very sad about what happened
another tragedy that cannot be avoided i will be hoping and praying for anyone there and i cannot even begin to imagine what they are going through
i feel sad because the picture shows the disaster of japan i wish i can help them.
i hope and pray that all these natural disasters get better and that people that live in japan survive these horrible things. i hope god and mother nature can help
i think this is very bad its soo sad>
oh no problem after problem every night i pray that everything will be good for everyone
We are seeing news channels and radio stations focusing on the effects of radiation in the U.S and it is natural to be concerned. Lets look at some hard facts -
The U.S west coast is 5000 miles away. So far, very dilute radiation - under one billionth of what is considered harmful level has been detected in California. Experts believe that most of the radiation will get washed away in the atmosphere and there is no health threat to the U.S - now if the reactors should have a meltdown, the situation might be different, but so far it appears to be under control.
i heard that there is radiation going towards florida. They are saying any food from like 10 to 20 miles is contaminated so no one is allowed to eat it or they have a chance of having cancer or other diseases
i hope that the radiation doesn't get close to ohio or any states in the U.S
I hope they can get back to normal soon.
so sad isnt it atleast the radiation did not affect the west coast
i think that is sad . but very shocking i hope that they get it cleaned up soon
why is this happening!!! not good for the world..
i dont see them coming back from this
It's in Japan's drinking water now.
So sad, isn't it?
At least the radiation did not affect the West Coast.
I doubt that the radiation could travel that far.