fun fact: fusion reactors don't produce corium either. their primary failure mode doesn't allow for production of hot, glowing, slowly cooling liquids. they typically would go out with a bang. And it's not so much the latent heat of the plasma, but the latent energy of superconducting coils to contain it that - if shorted or overheated - would blow the whole thing apart.
and here i thought nukes didn't produce corium ;) fun fact: fusion reactors don't produce corium ei