Nuclear power is still one of the safest and cleanest ways to produce electricity a4��a4� regardless of the doomsaying from the public and media after an 8.9-magnitude earthquake nearly caused a meltdown at the Fukushima Daiichi nuclear power plant in Japan.

Nuclear power is not well understood by the general public and the media. So the results of the disaster in Japan have been completely blown out of proportion, to the point that the U.S. government is calling on the president to back off on nuclear power programs for at least a little while.��U.S. senator Joe Lieberman made the call on CBS&' &''Face the Nation&'' today.

This is pretty unfortunate, because nuclear power is one of the next best alternatives to fossil fuel-fired plants. Other cleaner power sources, such as solar and wind power, are still in their infancy and are nowhere near as efficient as nuclear reactors.

Japan&'s nuclear reactors generate heat through a process called nuclear fission. This happens when uranium atoms collide with other particles a4��a4� typically a neutral particle called a neutron present in most atoms a4��a4� and split off into smaller elements. This reaction produces a tremendous amount of heat, which boils the water in the reactor, and several free particles. Neutrons are also among those particles, which then go on to collide with other uranium atoms in the reactor to create more nuclear fission reactions.

This type of reaction is called a chain reaction, because once it begins it creates a cascading effect that can continue for a long period of time. Reactors like the ones in Japan are able to control it by inserting an alternative type of rod that absorbs free neutrons. This lowers the probability of free-floating neutrons colliding with other uranium atoms, which would again create more heat and free-floating particles.

As the water within the reactor boils, it turns into steam. That steam is used to power a turbine that then creates electricity. It&'s a much cleaner procedure than a fossil fuel-fired power plant. The nuclear reactor is housed in several containment units, where each serves as a protective layer and a fail-safe for the one before it. Japan&'s nuclear reactors featured three containment units, the last of which is designed to &''catch&'' falling nuclear material after a meltdown and keep it from burning its way into the ground.

Several disruptions in external power to the nuclear plant eventually made it difficult to pump clean water into the plant and keep the nuclear fuel cool. The earthquake knocked the nuclear plant off the grid, but it had diesel generators. These were disrupted by the tsunami that followed the earthquake, forcing the plant to go to backup battery power while diesel generators were transported to the plant.

Eventually, no power was available, and the water level within the reactor started to fall as it continued to produce steam. Once the water level falls low enough to no longer cover the fuel rods, they heat up at a ridiculous rate a4��a4� to the point that they will begin to melt. Rather than let a meltdown occur a4��a4� which would have been caught by the third containment unit anyway a4��a4� Japanese officials decided to flood the reactor with sea water to keep the rods cool. This isn&'t the first option because it&'s easier for sea water, which includes salt and other impurities, to become radioactive by absorbing free-floating particles.

But it was the last line of defense for the reactor, and it was successful in averting a nuclear meltdown. Again, while a meltdown is a &''worst-case scenario,&'' it&'s still a controllable event that these plants are built to contain. The Chernobyl disaster, for example, was caused by excessive pressure build-up that triggered an explosion, flinging radioactive material into the atmosphere and the local area. This would not have happened in the Japanese nuclear reactors because there are methods to control the pressure build-up. It&'s comparing apples to oranges. The Chernobyl disaster was caused by a meltdown, but the radioactive fallout was not a product of the meltdown a4��a4� just the explosion that followed.

My understanding of the process comes from studying physics and mathematics as an undergraduate a4��a4� which isn&'t comprehensive. But Josef Oehmen, a research scientist at the Massachusetts Institute of Technology,��has a killer explanation that goes into a bit more detail about the explosion that occurred at the power plant. This explosion was caused by slightly radioactive steam &''dissociating&'' into oxygen and hydrogen outside the containment unit. The explosion didn&'t damage the containment unit, just the outside building a4��a4� which isn&'t supposed to serve as an additional layer of containment. It&'s basic chemistry a4��a4� hydrogen plus oxygen yields water and heat.

The situation hasn&'t been resolved just yet a4��a4� as it will take several days for residual heat to die down and ensure the reactions come to a complete halt. Because nuclear power is so sparingly used, something unexpected could still crop up.

The last time a nuclear disaster occurred in the United States a4��a4� the Three Mile Island incident in 1979, when a small amount of radioactive material leaked into the open air a4��a4� policies were stalled for more than a decade. With rising oil prices and the ever-present concern of greenhouse gases emitted from fossil fuel-burning power plants,��events in Japan a4��a4� no matter how much of a frenzy they have ignited in the media and in the public a4��a4� should not further delay the progress of nuclear energy in the United States.

[Photo: Paul J Everett, redjar]

[Update: I've edited the story to make the wording a little clearer in some places as per comments below and through various email messages. If anything is unclear, feel free to reach out and I'll work through it.]

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Tags: Fukushima Daiichi, Japan, japan earthquake, Japanese quake, nuclear power

Tags: Fukushima Daiichi, Japan, japan earthquake, Japanese quake, nuclear power

Matthew Lynley is VentureBeat's enterprise writer. He graduated from the University of North Carolina, where he studied math and physics, in May 2010. He has reported for Reuters. He currently lives in San Francisco, California. You can reach him at mattl@venturebeat.com (all story pitches should also be sent to tips@venturebeat.com), and on Twitter at @logicalmoron.

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