MONTREAL - The last major remnant of Saddam Hussein's nuclear program -- a huge stockpile of concentrated natural uranium -- reached this Canadian port Saturday, completing a secret U.S. operation that included an airlift from Baghdad and a voyage across two oceans.

The removal of about 550 tons of "yellowcake" -- the seed material for high-grade nuclear enrichment -- was a significant step toward closing the books on Hussein's nuclear legacy. It also brought relief to U.S. and Iraqi authorities who had worried that the cache would fall into the hands of insurgents or Shiites hoping to advance Iran's alleged nuclear ambitions.

What's left is the final and complicated push to clean up the remaining radioactive debris at the former Tuwaitha nuclear complex, about 12 miles south of Baghdad, using teams that include Iraqis recently trained in the Chernobyl fallout zone in Ukraine.

"Everyone is very happy to have this safely out of Iraq," said a senior U.S. official who outlined the nearly three-month operation. The official spoke on condition of anonymity because of the sensitivity of the subject.

Yellowcake alone is not considered potent enough for a "dirty bomb" -- a conventional explosive used to disperse radioactive material -- but it could cause widespread panic if incorporated in a blast. Yellowcake also can be enriched for use in reactors and, at higher levels, weapons.

The Iraqi government sold the yellowcake to a Canadian uranium producer, Cameco Corp.

A Cameco spokesman, Lyle Krahn, said the yellowcake would be processed at facilities in Ontario for use in nuclear power plants.

The deal culminated more than a year of diplomatic and military initiatives, kept hushed in fear of ambushes or attacks once the convoys were underway: first carrying 3,500 barrels by road to Baghdad, then on 37 military flights to the Indian Ocean atoll of Diego Garcia and finally aboard a U.S.-flagged ship for a 8,500-mile trip to Montreal.

Tuwaitha and an adjacent research facility were well known for decades as the centerpiece of Hussein's nuclear efforts. U.N. inspectors had documented and safeguarded the yellowcake, which had been stored in aging drums and containers since before the 1991 Persian Gulf War. There was no evidence of any yellowcake dating from after 1991, the senior U.S. official said.

U.S.-led crews transferred the yellowcake to secure barrels for the shipment.
© 2008 Associated Press