PARIS, Feb 1: France, Japan and the United States agreed on Friday to cooperate in making prototypes of so-called “4th generation” nuclear reactors, according to statements released by each country's energy ministries.

These sodium-cooled reactors, which would not come on line until mid-century, produce more energy per unit of fuel than nuclear reactors currently in operation.

But early prototypes have been plagued with problems. The liquid sodium cooling agent is highly volatile, bursting into flames if it comes into contact with air, and exploding if it comes into contact with water.

In 1997 France shut down its Superphenix reactor, while the Phenix, built earlier, is scheduled to close in 2009. Both are in southeastern France.

In Japan, the Monju reactor had to be shuttered after a fire broke out in 1995.

“Work is underway to resolve these problems, and the objective is to obtain safety levels at least as high as with third generation reactors,” an official in France's Atomic Energy Commission (AEC), Sunil Felix, told newsmen.

The memorandum of understanding, also signed by Japan's Atomic Energy Agency and the US Department of Energy, seeks to “avoid duplication in technological development” by adopting common standards for the prototypes, the AEC said in a statement.—AFP