If there is 'some' fallout, then of course the debate will rage on indefinitely. Which is why I did not suggest the converse position that you put forward.
Why should one outcome produce a change in behavior from one crowd, but the opposite outcome should not produce a change in behavior from the opposite crowd?
Until the results are in there will also continue to be a lot of nuclear-is-perfectly-safe sensationalism (in the past hour I saw a couple of them on CNN). Do you expect and/or hope for retractions on those wildly optimistic statements by "experts" if there is "some" fallout, as you'd like to see in the reverse scenario? If so, I suspect you won't get them, though it does not really appear you'd be looking for them anyway.
Additionally, it's not clear to me why one case where there are no adverse affects (again, ignoring the fact that there are already adverse affects) is of monumental importance (a type 1 error), but the numerous cases of historic failures are not valid considerations in the same degree. Put another way, why should the hypothetical of a positive outcome of this situation have any more weight than the negative outcomes of numerous previous situations?
Also, "safe" is relative. Walking down the sidewalk in a good neighborhood is generally considered safe, but it is dangerous relative to sitting in a fortified bunker. If the impact is several orders of magnitude less than we'd expect from, say, coal, then we can say this was very safe indeed.
Except there are numerous "ancient" plants in full operation today. Except Japan is one of the most organized, efficient and technically advanced societies on the planet.
Most importantly, you fail to address my actual question: why should nuclear doom sayers have to recant their concerns in the event they are mistaken but nuclear cheerleaders do not in the event they are? You and the OP wouldn't answer that question because you have no logical answer.
But if the situation blows over without a large number of people being affected by harmful radiation, if the failsafes work despite multiple catastrophes (which almost certainly wouldn't threaten most plants), then the doom sayers really should admit nuclear safety is feasible, if they want to maintain any integrity.
No, they really should not.
Firstly, you've moved the goal posts - now safety should be accepted up until a "large number of people become affected by harmful radiation". Originally, your goal posts were set to "Japanese people escape unscathed from radiation". And I suspect the definition of "large" will shift accordingly so that you can maintain your view that nuclear plants are safe enough. You had to shift your goal posts because the glowingly optimistic view from your OP hasn't survived reality.
Secondly, if that glowingly optimistic view from your OP had actually come to pass (and now we're operating in a fantasy world), why would anyone consider it more than anecdotal or luck or a combination of factors that are not easily quantifiable and therefore hardly reproducible?
And lastly, once again you failed to address the point I have been making. Your position applies equally to both sides. You can't cherry pick and maintain any integrity. It's not that I believe failure in this situation is ultimate proof of the failure of nuclear energy - but it is your OP that success in this situation is ultimate proof of the success of nuclear energy. Your premise is wrong, independent of whether your conclusion is wrong (which I believe it is, but not ultimately because of this situation).
Obviously there can be no 'ultimate, ultimate proof' unless we get a direct line to God, but if you're going to be the person standing on top of the hill saying
'I don't care if you can show nuclear plants can withstand unheard of earthquakes and tsunamis, I don't care if there's 50 years of further research and improvement on those standards, I still wont believe nuclear power is safe. In fact there's pretty much nothing that would sway my assessment of nuclear safety...'
then I don't see why anyone should take you seriously.
edit: oh, and let's just wait for the clear light of day before we decide what exactly 'the situation' really is/was. I've seen many conflicting and retracted reports so far
And no, I don't suspect the anti nuclear crowd will buy it at all.