Quote:
Originally Posted by kirant
Sorry. Maybe I'm just a bit ambiguous: I was wondering what the chances of a full runaway reaction occuring were given the fact that a partial meltdown had begun (if they are known at all. I suspect this may be something a nuclear physicist would be required for).
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Yeah, and even then you're talking about a lot of different variables and the chances are going to vary greatly depending on what exactly happens.
There's some discussion about failure modes and mitigation here:
http://www.osti.gov/energycitations/...sti_id=5642843
Quote:
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In scenarios of small-break LOCAs, there is generally a pool of water in the lower plenum of the vessel at the time of core relocation. Release of molten core materials into water always generates large amounts of steam. If the molten stream of core materials breaks up rapidly in water, there is also a possibility of a steam explosion. During relocation, any unoxidized zirconium in the molten material may also be oxidized by steam, and in the process hydrogen is produced. Recriticality also may be a concern if the control materials are left behind in the core and the relocated material breaks up in unborated water in the lower plenum.
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That's recriticality though and not really a full runaway reaction (though really the difference is just in degree I guess). Because the melted material (corium they call it lol) contains not just the nuclear material but the control rod material and all the other stuff that got melted along with it, it's probably really hard to say exactly what the chances are.
The wiki for corium is pretty interesting:
http://en.wikipedia.org/wiki/Corium_(nuclear_reactor)