ST. PETERSBURG, Russia (AP) — A 20-year program to convert highly enriched uranium from dismantled Russian nuclear weapons into fuel for U.S. power plants has ended, with the final shipment loaded onto a vessel in St. Petersburg's port.

The U.S. Energy Department describes the program, commonly known as Megatons to Megawatts, as one of the most successful nuclear nonproliferation partnerships ever undertaken.

The agreement, signed in 1993 shortly after the collapse of the Soviet Union and scheduled to run until 2013, gave Russia the financial incentive to dismantle nuclear weapons.

In the two decades since, 500 metric tons of highly enriched uranium, the equivalent of about 20,000 nuclear weapons, has been converted into fuel for U.S. nuclear reactors.

U.S. and Russian officials saw off the final shipment of the low-enriched uranium on Thursday.

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