I noticed in Arnie Gundersen's video with Helen Caldicott (linked above) that no data about the status of unit 3 have been released;
Gundersen says unit 3 is the worst, and carefully avoids talking about it, despite Helen's prodding.
He quickly transitions away from unit 3 with the startling observation that each of Fukushima's reactors contained a ton of plutonium dispersed in the fuel because fissioning produces neutrons, which are absorbed by U-238 in the fuel, and transformed into plutonium.
How much plutonium was in reactor 3?
The range for Mox assemblies believed to have been inside reactor 3 range from 164 assemblies to 32 mox assemblies. At the low end estimate of 32 mox assemblies, we still get a scary total of 5.5 tons of fuel containing more than 300 kg of plutonium. http://www.fukushima311watchdogs.org/biblio/9/Mox%20fuel-corium-plutonium%20in%20Fukushima%20Daiichi.pdf
Now we can add in the 1 ton of plutonium from unit 1 and 1 ton from unit 2.
Of course, we do not know where that plutonium is. Hopefully most of it is still intact in the fuel.
Still, the state of reactor 3 suggests that the plutonium from that fuel was dispersed far and wide.
I cannot help but thinking of Bruce Springstein's song: Further Down the Road:
Got your dead man's suit on and your lucky graveyard boots?