With the steam flowing continuously (nighttime pictures) we have a possibly continuous, unpredictable source of I-131 with unknown volume. So with only one sample (I know about only one sample) any deep 'analysis' is just guessing.
It'll be this one I think: http://cryptome.org/0003/daiichi-assess.pdf
All it has is:
What's only a 'may have been'.
IMHO it's unlikely that fuel ejected, and found only a mile away and right near the reactor, and nowhere else around the site (it's quite easy to notice ejected fuel by the alarming dosimeters :-) ). So that early 'may have been' actually is a 'not likely' and should not be taken as a fact and used as backup for wild speculations.
PS.: of course: IMO.