this is probably a really stupid question with a really obvious answer, but i just learned that in nuclear power station reactors they use graphite rods to slow down the reaction in the uranium if it's going too fast. So i was wondering, why don't they just coat the outside of the reactor in a really thick layer of graphite so if a meltdown occurs, the outer layer will absorb all the neutrons and the meltdown would have a chance of stopping?

[This message has been edited by Haddock (edited 11-18-2002).]

Slow not stop the radiation. and it would take alot of graphite to do that.

By the time the nuetrons reached the walls several feet away they will have already reached the urainium inches away.
EDIT: bad spelling
CTR

[This message has been edited by Genital-Warfare (edited 11-18-2002).]

The neutrons are absorbed by the rods so they don't get to the uranium and continue the chain. When the chain reaction gets out of control too much heat is created and then a meltdown occurs.

So the rods just stop the neutrons they don't stop heat and graphite is definitely not tough enough to hold in plasma if the reaction were allowed to runn away.

Meltdown: when the nuclear fuel reaches such a temperature that it melts

Once you have a molten puddle of uranium you lose all control over it. With no way to stop it from reacting it will continue to heat. Once it gets hot enough, or begins to drip through to the water tank, the water turns to steam. With extreemly high pressures. The concrete walls (known as a containment dome) are built to withstand the incredible pressures generated by this. If there is a small flaw in the containment dome you get 3-Mile Island. If there is a large flaw you get Chernyobl.

the walls are there to keep stuff in as WELL as out. they've crashed jet fighters (on rocket sleds) in the walls during testing. graphite is reather brittle isnt it? not as stong as reinforced concreate.

they dont use graphite ont he dome.. and i heard of somehting newer. there using graphite/uranuim balls instead rods. when it gets to hot they just add a whole shit load of graphite balls and mix it up and the graphite will abosorb all teh radiation.

er spomehting like that

What is new in the nuclear industry is ceramic fuel. Ceramic pellets with a high concentration of uranium are used in the fuel rods rathar than plain uranium. This way they can not melt, causing a meltdown.