nuclear reactor core melt down?

Question

it has been said that if the core was to go into full melt dowm it would pass clean through the planet and pass out the other side. my question is, as the core reaches the centre of the planet would gravity not slow if down and hold the molten core in the centre of the planet as the force of gravity would be equal?

Answer 1

A bit of exaggeration, the premise is that if a core "melted" it could because it was hot enough and dense enough to melt through the ground and soil.

Only for a few of the biggest nuclear reactors of some designs would they even reach a critical mass to "melt" the rock and soil immediately below them. However a meltdown without that happening to significant extent could still be quite bad as in Chernobyl.

The total core meltdown sinking through the earth would presume that the core stays intact and hot enough to tunnel through the rock.

In nearly all cases once such a core was melting down it would break up in a steam explosion when the core hit the water table and the resulting fragments would no longer be hot enough to tunnel into the earth.

In the less likely event that the steam explosion did not happen, the core would fragment into pieces as it descends into the earth, and this would certainly happen when it hit the molten mantle 50-100 km down into the earth.

In any case such an accident would not only require very poor reactor design and incompetent operation. Trying to get such a "disaster" to occur intentionally would be nearly impossible without a lot of effort and work even if a rogue state or terrorist group seized a nuclear plant and maintained control for several days.

Answer 2

This wouldn't happen in practice. The exposed core would catch on fire. All metals burn at some point when they get hot enough. This is what happened at Chernobyl. That is why there was such an incredible release of radiation - the core burned away.

Note that Chernobyl was a full blown meltdown, unlike Three Mile Island. The core did not end up in the center of the Earth.

Answer 3

It has been said? By whom?

Whoever said that was either joking, or has no clue what they're talking about. The core of Chernobyl's reactor #4 went into full melt down and nothing of the sort happened.

Answer 4

The molten core would have momentum which would carry it further, however I think that once it encountered the molten center of the earth it would kind of just get mixed in.

Answer 5

yes but meltdowns wont reach the centre of the earth

Answer 6

Erm, dunno. Don't really fancy finding out, either.