Confirmed nuclear meltdown in Japanese reactor

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Actually the internal heat of the Earth is more dangerous. The Siberian Traps were a million year long volcanic eruption that nearly killed all life on this planet.

See:
http://en.wikipedia.org/wiki/Siberian_Traps

Warming due to CO2 has been nowhere near as destructive.

ruveyn

Yes so when the next deadly volcano hits blame it on that dangerous nuclear fission reactor located in the center of the Earth.

in the words of the father of the nuclear navy: I do not believe that nuclear power is worth it if it creates radiation. Then you might ask me why do I have nuclear powered ships. That is a necessary evil. I would sink them all. I am not proud of the part I played in it. I did it because it was necessary for the safety of this country.[...]"

i feel the same way, with most of his views.

With the exception that third, fourth and fifth generation reactors are no less than at least two orders of magnitude safer than the reactors that are currently in operation now.
And, the safety and living standards of the entire earth are at stake if we do not find a cheap energy supply.
peak coal, is either this year or 2012, peak oil was 2005. we're 10 years behind the power curve.. literally.
right now the only thing driving the electrical grid's growth is natural gas, and that is the feedstock for... fertilizer!

Back to TEPCO.. they are now admitting that the meltdown started 16 hours after the earthquake!
this concerns me. we still can't get good information from them. I read that they released some 2900 pages of documents very recently, i have not had the time to look for them yet.

Coal power stations actually produce more radiation than nuclear power stations.

That is literally correct.

The internal heat of the Earth is largely produced by nuclear fission. Aside from producing volcanoes the internal heat keeps the iron core of the planet in a liquid state do it can continue to general the magnetic field which protects us from extreme solar radiation.

ruveyn

Chernobyl was an entirely different scenario. The design of the Chernobyl reactors made them inherently unstable. They were water cooled and used graphite as a moderator.

The job of the moderator is to slow neutrons to allow them to be captured by an atom of the fuel material such that the atom destabilizes and falls apart, releasing more neutrons to continue the process.The water was to cool the reactor but also had the side effect of absorbing some neutrons. If voids formed in the reactor, for example, from water leaking out or boiling, less neutrons were absorbed and the graphite moderator allowed them to react, so the reaction rate inside the reactor would increase. In other words, if it lost it's water, the reaction would not only continue but go out of control.

The control rods, which are rods which can be lowered into the reactor to turn it off, because they are made of materials that absorb neutrons, had leaders on them, made of boron, the same material as the moderator, followed by a hollow section. If you imagine the reactor encased in a boron shell, and the rods pulled all the way up (reactor at full power), you can envision the boron leaders plugging the boron shell.

At Chernobyl they wanted to do a rather stupid experiment. The reactor had to be cooled even after it was shut down because the residual reactions generated enough heat to damage the reactor. They wanted to see if the momentum of the turbines used to cool the reactor was enough to continue to cool the reactor in an off state for x amount of time if the power to them was cut. This experiment was to be done by the day shift but they were delayed in starting it, and the day shift started the experiment and left the night shift to complete it. The night shift operator wasn't familiar with what was going on and was told to follow instructions which had been written.

Rather than shut the reactor down completely, the night shift operator was to bring the reactor down to a low power state. The reason given was that shutting the reactor down completely would have caused xenon poisoning and they would have had to waited a period of time to bring the reactor back online.

The night operator accidentally brought the power down too low. He instantly realized his mistake and tried to bring the power back up to the level indicated by the experiment but the reactor wasn't responding as xenon had already started to build up. The operator over corrected, and pulled the control rods all the way out of the reactor, beyond the safe operation specifications for the reactor. Keep in mind there is no power to the cooling system. The reactor output spiked as the reactor suddenly overcame the xenon poisoning and went full throttle and the water began to boil, creating steam voids and increasing the power output further. Realizing the runaway reaction, the operator hit the scram button. This is an emergency button that drops the control rods down into the reactor to shut it off.

But guess what. Those control rods were tipped with boron leaders...a moderator, followed by voids. A very very very bad design. When the control rods were introduced back into the reactor, the boron in them followed by the voids momentarily increased the reaction rate, and this was enough to cause enough heat and pressure such that the gases within the reactor ignited and the reactor blew up. This happened in less than 30 seconds from the time the night operator sat down. Chernobyl reactors did not have full containment units. The reactor vessel sat on a lower containment foundation but there was no upper outer containment. The reactor lid was the floor of an ordinary building.

The reactors at Fukushima are boiling water reactors. The water serves as a coolant and moderator. If the water leaks out, the chain reaction cannot be sustained. The problem is, the reactor is still hot enough to need to be cooled for some time after the chain reaction has stopped.

A meltdown just means it's gotten hot enough for the fuel rods to melt and the reactor has likely been permanently damaged. If the reactor was not shut down before hand, they can't get the fuel rods down into it to shut it off. Then, the reaction technically becomes un controlled. It does not necessarily correlate with a release of radioactive materials into the environment. Whether or not radioactive materials are released depends on the containment system. One big fear in meltdowns is that the hot fuel will melt it's way down to a pool of water under the reactor, or the water table, and cause a massive steam explosion resulting in acute and widespread environmental contamination.

Chernobyl didn't quite melt down. It blew up first and did cause extreme, widespread environmental contamination.

At Fukushima, there was an explosion but the reactor was not undergoing a runaway chain reaction when it occurred and it's entire contents was not scattered into the environment thanks to the containment unit. The explosion may have occurred within the containment unit but outside of the reactor vessel as well. However the containment unit was apparently damaged from the earthquake/tsunami and may have actually been leaking before hand.

Any melt down at Fukushima was likely a slow moving process. Whether further explosions are imminent depends.

However there is the issue of the fact that most reactor events involve one reactor, and at the Fukushima plant, multiple reactors are in trouble.

Consider though environmental contamination from other power generation methods. Oil drilling actually producing a significant amount of radioactive waste a year and the burning of fossil fuels releasing a significant amount of carcinogens and naturally radioactive elements into the environment. While the pollution isn't necessarily as acute as that seen with nuclear accidents, it's likely that illness from fossil fuel based power generation is responsible for the death of tens of thousands of people per year.

Solar cell production isn't a particularly clean process. The material has to be mined and refined and the fabrication processes requires a significant amount of heat energy, as well as uses many toxic chemicals. Not to mention the fact that's it's not suitable for places where it tends to be overcast much of the year.

Hydroelectric is clean but requires dams and water to flow through them. The dams usually have to be built which involves flooding one area restricting water to another and can cause serious ecological disruption.

Wind is nice but it's not always windy, and geothermal is great but not an option for most places, and biofuels aren't easy to make and tend to cause humanitarian problems.

Nuclear, done right, gives us the most power and the least environmental contamination. Do you think the environmental impact of Chernobyl, Fukushima and Three Mile Island combined are greater than that caused by fossil fuels cumulatively?

Honestly I don't know that it's possible to say one way or another but it's something to think about.

and wind turbines kill birds.

good points. there's no perfect solution to the dilemma, and it's compounded by the fact that the oil industry and the nuclear power industry are notorious for downplaying (or hiding) damage from accidents, lobbying for fewer environmental regulations and steamrolling anyone who interferes with their ability to profit astronomically.

TEPCO is very well known for falsifying records pertaining to safety investigations and has not exactly been transparent in regards to this whole mess.

in short if anyone who profited off of oil drilling or nuclear power could be relied on to put safety above profit, we would have a different world on our hands.

I used to live about 10 miles away from one. OMG

The solution is clear. Charge for externalities. Charge people who pollute the water and the air for the damage the do. Then the cost of creating externalities will be an incentive to cleaner operation. As long as we enable pollution by permitting to occur without a cost to the polluter we will have pollution.

ruveyn

and the rest of my comment said that the modern nuclear reactors are a few orders of magnitude safer than the ones we've got now, and that the safety of the entire world is at stake if we don't find another source of energy.

i know some guys who have worked in open pit mines, coal power plants. i don't think they should exist either and i did not suggest that we build more. but the alternative is burn more natural gas...?!

just look at the fact that the 23 or was it 17 reactors in the states that are the same model as the ones in japan... ours have an average of 8 full reactor cores stored in the cooling ponds, because we're not allowed to store them in dry casks, or bury them in a 5000 foot deep hole. and a lot of ours are MOX fuel as well.

the other day tepco said the radiation in the reactor buildings was still as high as 5 rem per hour.
and they have built two forklifts with 10 cm thick steel and 10cm leaded glass to protect the operators.
something don't add up there.... they are not telling us the complete situation.

No the better alternative is nuclear energy. Its actually much cleaner and safer than the coal energy. Even if you take into account the number of people who died from cancer due to the Chernobyl accident, there have been coal mining accidents that killed more people.

Burn ecology, not coal.

ruveyn

I say burn atoms. All types of energy generation have some kind environmental risk associated with them, including the renewable kinds. The environmental risk associated with nuclear power only really comes into play in the event of a nuclear accident as the waste can be reprocessed or disposed of safely. On the other hand, other viable types of energy such as coal, natural gas or oil release tons of waste into the atmosphere. Add to that, that oil spills are far more common than nuclear accidents. Evidently, nuclear power is much less damaging to ecology than the other forms of power we are using, so there's no need to burn ecology either.

One does not burn atoms, one might split atoms or allow them to split and collect the energy created by the mass deficit. I agree. Fission power is the way to go, especially with the new generation of safe breeder reactors.

ruveyn

They actually just kind of fall apart.

This is hiiiilarious. It was obvious 3-4 days into the disaster that they've had:

1) at least partial meltdowns (no other process can produce so much Hydrogen to rip apart reinforced concrete buildings, and also the presence of huge quantities of water soluble isotopes which typically do not leave the fuel rods unless the rods have melted)

2) loss of containment (coolant water leaking out by the thousands of tons, and atmospheric pressure in PVs of reactors 2 and 3)

It is obvious today that they will not be able to establish primary loop cooling and then perform a TMI style cleanup. The reactors will be entoumbed and the entire area will be abandoned. It would be political suicide to admit that, so TEPCO is flailing about and delaying announcing the obvious until the eyes of the World are no longer upon Fukushima.