U.S. buying 32 metric tons of heavy water from Iran

The United States is buying 32 metric tons of heavy water from Iran, U.S. congressional and administration sources said on Friday.

The purchase will be under $10 million, the congressional sources said.

Heavy water is a form of water that contains a larger than normal amount of the hydrogen isotope deuterium

It is used in certain types of nuclear reactors, where it acts as a neutron moderator to slow down neutrons so that they are more likely to react with the fissile uranium-235 than with uranium-238, which captures neutrons without fissioning. The CANDU reactor uses this design.
Reuter, YL