At a nonproliferation summit Monday in Washington, Obama will encourage leaders from 47 countries to work with the US to secure and remove highly-enriched uranium from reactors, as Chile finally did last month.

In a classified operation, the US National Nuclear Safety Administration, in co-operation with the government of Chile, removed about 39.6 pounds of uranium rods for re-processing in South Carolina.

The head of Chile's Nuclear Energy Commission was happy to see the fuel go, given the expense and extraordinary security needed to protect it.

Scientists say 55 pounds of HEU in a nuclear bomb could devastate an entire city.

Scattered at sites around the world, such material needs constant guard.

Obama is hoping that other countries will agree to follow Chile's example when they meet in Washington, DC.

AP