What Is A Nuclear Meltdown?

[tuannguyen]

Ever wonder what a nuclear meltdown actually is?

What Is A Nuclear Meltdown? : Read more

 

[amk09]

Yikes, wouldn't this be especially devastating since japan is so small?

 

[captaincharisma]

oh thats what it is. i thought it was what charlie sheen is having WINNING

 

[tmax]

Nice summary Tom's.

 

[nexus9113]

The biggest danger of a melt down is not the explosion of the containment chamber, but the possibility of the fuel becoming so hot that it burns through everything it comes into contact with, which will result in what is known as "China Syndrome", a slang term coined by US nuclear engineers meaning that the "rock" can get so hot when unchecked it could melt straight through the planet to China if it didn't hit any cooling material.

The issue with that situation is that it is highly likely the "rock" would hit an underground source of water before it got to the other side, instantly vaporizing all the liquid into extremely high temperature steam, increasing the pressure in that pocket exponentially, and creating an explosion of contaminated steam that would jet into the air like an explosion, destroying the area around the meltdown, contaminating the atmosphere, and distributing fallout for an incredible distance (Chernobyl was literally felt around the world to some degree).

 

[Snipergod87]

Graphite control rods are not used much anymore, tends to be boron or berrilium, which works better. Graphite was used at Chernobyl.

The Chernobyl accident was caused by an expirment, they were trying to see if they could run the coolant system off the residual heat from the reactor instead of generators, however the reactor cooled down faster than expected, so they pulled the rods out, however they pulled them to far out causing an uncontrollable chain reaction.

Nuclear reactors are very stable when running, however during the shutdown or startup process they are very unstable.

 

[christop]

I feel sorry for the people of Japan.

 

[xantek24]

thats funny, the same thing can happen to my gtx470 if dont keep it submerged in water...

 

[ananke]

The graphite particilce in Chernobyl were the main problem - the graphite evaporated and its particicles carried plutonium atoms in the athmosphere.

Japan's reactors are not using graphite rods, but if a meltdown and explosion occurs, at least the near vicinity of the plant will be poisoned due to the radioactive water vapors. I doubt the particicles can fly too far without a career - such as graphite. Berillium doesn't have the same physics, it will not fly in a cloud.

 

[jnc852]

Hmm....I bet coal fired generation isnt looking so bad in the eyes of many anymore.

 

[jerreece]

[citation][nom]nexus9113[/nom]The biggest danger of a melt down is not the explosion of the containment chamber, but the possibility of the fuel becoming so hot that it burns through everything it comes into contact with, which will result in what is known as "China Syndrome", a slang term coined by US nuclear engineers meaning that the "rock" can get so hot when unchecked it could melt straight through the planet to China if it didn't hit any cooling material. The issue with that situation is that it is highly likely the "rock" would hit an underground source of water before it got to the other side, instantly vaporizing all the liquid into extremely high temperature steam, increasing the pressure in that pocket exponentially, and creating an explosion of contaminated steam that would jet into the air like an explosion, destroying the area around the meltdown, contaminating the atmosphere, and distributing fallout for an incredible distance (Chernobyl was literally felt around the world to some degree).[/citation]

Bethesda already made that game...

 

[dark_lord69]

I saw a video explaining what happened in Japan in at least 1 location.
1. The quake caused a power outage so the main water cooling system shutdown.
2. A backup system powered by a diesel engine turned on, to pump cooled water back into the reactor. But, A tsunami put the diesel engine under water and caused that to fail.
3. A secondary backup system turned on. It simply collects steam and allows it to cool back to water before putting it back into the core. BUT the steam built up and the water level was low while running this third system. They shutdown the core and had to pump sea water into the core to cool it. The person in charge that was interviewed said that they believe there must have been a water leak in the 2nd backup system that caused the steam to build up and the water level to get so low. (The amount of water should have been a steady amount.)

Guess that is what happens when you have an earthquake followed by a tsunami.

 

[mlopinto2k1]

[citation][nom]Snipergod87[/nom]Graphite control rods are not used much anymore, tends to be boron or berrilium, which works better. Graphite was used at Chernobyl.The Chernobyl accident was caused by an expirment, they were trying to see if they could run the coolant system off the residual heat from the reactor instead of generators, however the reactor cooled down faster than expected, so they pulled the rods out, however they pulled them to far out causing an uncontrollable chain reaction.Nuclear reactors are very stable when running, however during the shutdown or startup process they are very unstable.[/citation]Zirconium is mainly used.

 

[Nightskeeter]

the water vapor, may get into water streams, and spread to a larger area/get absorbed into livestock, trees, plants. ETC. What makes you think just cause it isn't Graphite that it wouldn't be catastrophic? It's a tiny little island, with a butt load of people.

But then again, I dont know much about this, but when I watched a show on Nat geo about nuclear meltdowns the other night. Water could, and would be contaminated. so would plants. that they eat. and plants will continue to even give off the poison even in the fruits AKA apples, and such. the toxins still exist in chernobyls plants and trees, even the dirt still has the toxic fallout radiation in them. So I don't see how, toxins can fly as far as they want using, Tsunami WAVES. Air. Clouds. Rain.

 

[cjl]

There's a lot of misinformation here. Although a meltdown will severely damage a powerplant, modern powerplants are unable to have anything like what happened at Chernobyl. Chernobyl had no containment vessel, and a poor design which resulted in an explosion in the core, spreading radioactive waste far and wide. A modern reactor, if it were to melt down, would still have everything in the containment vessel. It would just be in a molten puddle in the bottom of the containment vessel. No substantial radiation would escape, and there would be effectively no danger to the surrounding population.

For a much more detailed explanation of what's going on in the reactors right now, see here:
http/morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/

 

[zerapio]

So will duck and cover help?

 

[robochump]

[citation][nom]amk09[/nom]Yikes, wouldn't this be especially devastating since japan is so small?[/citation]

Doesn't help that these Nuclear Reactors are right next to the ocean and can potentially poison thousands of miles of Ocean wildlife I hope Japan and friends can bottle it up with no leakage!

 

[godnodog]

What Is A Nuclear Meltdown?

It´s a RUN FOR YOUR LIFE situation

 

[LePhuronn]

And the Japanese haven't just filled up the containment chamber with boron powder why? Standard failsafe equipment over here in the UK (IIRC, of which I probably don't).

Kills the reactor stone dead yes, but the fission reaction stops as every particle gets soaked up.

 

[bayouboy]

[citation][nom]nexus9113[/nom]The biggest danger of a melt down is not the explosion of the containment chamber, but the possibility of the fuel becoming so hot that it burns through everything it comes into contact with, which will result in what is known as "China Syndrome", a slang term coined by US nuclear engineers meaning that the "rock" can get so hot when unchecked it could melt straight through the planet to China if it didn't hit any cooling material. The issue with that situation is that it is highly likely the "rock" would hit an underground source of water before it got to the other side, instantly vaporizing all the liquid into extremely high temperature steam, increasing the pressure in that pocket exponentially, and creating an explosion of contaminated steam that would jet into the air like an explosion, destroying the area around the meltdown, contaminating the atmosphere, and distributing fallout for an incredible distance (Chernobyl was literally felt around the world to some degree).[/citation]

As, CJL already stated, nothing of what you said has any reality to it.

Molten fuel rod assemblies, while extremely hot and completely unable to melt though the containment shield, simply takes far too much energy. The idea that it would then continue on through the rock surface below is just pure fantasy.

Chernobyl was an EXPLOSION. There was no containment shield and the reactor was opened to the environment. Steam and pressure vented a significant amount of radio-nucleotides into the air which was carried downwind. This is not a very likely scenario in Japan as their NPPs have containment shields.

To date, there has only been one real world test of a containment shield and that was 3 Mile Island, and it performed spectacularly well. A full scale meltdown and the molten fuel assemblies were unable to breach the containment shield.