I don't think he ever said that. Do you have a citation?
It is common knowledge that Iraq has yellowcake. Go to Google and search for Tuwaitha. Evidently the US wasn't too concerned about the yellowcake stored there, as the facility wasn't secured until weeks after the Iraqis abandoned it.
Tuwaitha was heavily looted, with many people taking contaminated drums to store their water in. There were stories about US troops having to spend their time tracking down some of these things and try to explain to the locals why it isn't a very good idea to drink out of something like that.