Where is the U-234 and U-238 coming from?

[SpoonFed]

We've seen discussions on radioactive iodine and cesium, and venting of steam from the reactors and talk of breached or broken cores, but what is missing from the discussion is where this increase in uranium that the recent EPA report has disclosed is coming from.

From what I understand iodine and cesium have relatively low boiling points (compared to U and Pu) and somewhat soluble in water. Where did this EPA-detected elevated levels of uranium come from?

A few ideas possibilites come to mind,

a) one of the units burned off some fuel in their storage pools
b) unit three's large explosion jettisoned fuel and reactor products into the jet stream

Other ideas?

(I've heard the coal burning in China theorum but don't really but it as anything other than nuke industry prop at this point.)

If a) and/or b) are true, that means there is some percentage (1% to 7%) plutonium floating around someplace, also?

[FBaggins]

1. From the core or pools.

Probably the core.

The uranium wouldn't have to reach a boiling point in order for very small amounts to have been carried physically in other releases. If the relase were many orders of magnitude larger, we would have to worry about volatility and how it reached the boiling point... but not in this case. I think even the wildest theories of what happened in the reactors wouldn't include 7,000 degree temperatures.

And yes, probably something on the order of 1% of that amount can reasonably be assumed to be the amount of plutonium released.

I haven't seen a breakdown of the proportion of U234 to U238, but since the amount detected is so far below normal background levels, the only way the EPA could have associated it with Fukushima would be that U234 was in there in amounts many times greater than in natural uranium (indicating that it had at least been enriched for reactor use at some point).

I haven't seen a theory related to burning coal, but (given the above) I don't see how it makes sense.