1.   As a private company, it would be strongly tempted to cut back or even eliminate purchases from Russia, possibly by flooding the market with cheap natural uranium.

2.   But the exemption does not apply to the natural uranium component, which represents roughly a third of the value.

3.   Highly enriched uranium can be rendered relatively harmless by simply blending it with nonexplosive natural uranium for use as reactor fuel.

4.   Like plutonium it can be used to make bombs, but larger quantities are needed and it is more easily rendered useless for weapons through mixing with natural uranium.

5.   Large stockpiles of natural uranium also remain in Iraq.

6.   Natural uranium is made up of a mix of isotopes, or different forms of the same element.

7.   One source in geologic formations is radiation from natural uranium, which breaks water molecules into hydrogen and oxygen.

8.   Or the converted plutonium oxide could be mixed with natural uranium oxide and used as nuclear reactor fuel.

9.   That action also made the sale in the United States of the natural uranium in the material nearly impossible.

10.   The main problem addressed on Tuesday by the Senate Energy Committee is how to pay Russia for the natural uranium being used to dilute the bomb-grade uranium.