[ttfkam]

> I don't see how one can possibly do that analysis.

Classic argument from ignorance fallacy. Because YOU cannot see how it could be done, no one has ever figured out how it could be done.

[pfdietz]

You didn't answer the question.

All the analyses I've seen for fast reactor safety are about avoiding fuel melting, not what happens if the fuel does melt. The variability in this latter scenario is so great that conclusive analysis ruling out disaster doesn't seem possible. Maybe you could explain the unexpected principle that enables one to do that? Or, lacking that, point me to a paper where such analysis has been performed.