Amos et al, go back and read IAEA's reports relating to Saddam Hussein's research and development programme related to his quest for nuclear weapons.

In their experimentation to find the means to enrich uranium to weapons grade they were looking at five different methods of doing so. Now that just might explain why they would require rather massive quantities of the stuff and why they could be on the look-out for more.

This by the bye I remember vividly as part of the early reporting in the Spring early Summer of 2003:

""U.S. and Iraqi forces have guarded the 23-acre (9,300-hectare) site—surrounded by huge sand berms—following a wave of looting after Saddam's fall that included villagers toting away yellowcake storage barrels for use as drinking water cisterns."

The coverage was of the Tuwaitha facility in Iraq. Now who was it that put forward the contention that the US shipped it in, in order to discover it and ship it out again? Yellow Cake certainly did exist and was discovered in Iraq in 2003, undeniable fact, it's on record by both the IAEA, UNMOVIC and MSM. Those sources will probably not be good enough though.