U.S. Trims Nuclear Material Stockpile

Secretary of Energy Samuel Bodman announced Nov. 7 that the United States would reduce by 200 metric tons the amount of highly enriched uranium (HEU) stockpiled for nuclear weapons. Once the decades-long process is completed, the United States would still retain hundreds of metric tons of this nuclear bomb-making material.

Nuclear weapons require plutonium or HEU to function. A typical U.S. nuclear weapon employs both, a plutonium primary and an HEU secondary.

The 200 tons of HEU, which Bodman said could produce 8,000 weapons, would be allocated for three different purposes. The largest portion, 160 metric tons, would be reserved for powering the U.S. Navy’s nuclear vessels, currently numbering 82 submarines and surface ships. Bodman claimed this move would postpone the need to build a new naval HEU fuel production facility for at least 50 years.

Another 20 metric tons would be preserved for reactors burning HEU fuel and for space missions. The reactor fuel would be needed primarily during a transition period until 2014 when Washington hopes to complete work on converting 105 research reactors worldwide to operate on less bomb-ready fuel known as low-enriched uranium (LEU). By contrast, “space reactor applications would be minimal at this time but may evolve as NASA reexamines its long-term mission needs,” a spokesperson with the Energy Department’s semi-autonomous National Nuclear Security Administration e-mailed Arms Control Today Nov. 18.

The remaining 20 metric tons would be blended down into LEU for purchase both by domestic and foreign users. This amount is distinct from the September U.S. initiative to blend down 17 metric tons of HEU for an emergency LEU fuel reserve. (See ACT, November 2005.)

The HEU stockpile size for military purposes—weapons and naval fuel—is classified, but government disclosures and actions have provided some basis for estimating its magnitude. In June 1994, the Energy Department revealed that until 1992, when it ceased production, it had churned out 994 metric tons of HEU. Months later, the Clinton administration declared 10 metric tons as excess to the military stockpile and subsequently approved removing another 174 metric tons.

The non-governmental Institute for Science and International Security (ISIS) estimates that the U.S. weapons-grade HEU stockpile, including material in existing warheads, equaled roughly 480 metric tons at the end of 2003. This estimate factors in past use for nuclear weapons tests and other purposes, double counting of some production, and the presumed assignment of 100 metric tons for naval fuel purposes. ISIS also calculates that the U.S. plutonium weapons stockpile at that time amounted to about 47 metric tons.

The latest move when fully implemented would then leave the United States with approximately 280 metric tons of weapons-grade HEU. This translates into enough material for roughly 11,200 nuclear warheads, using Bodman’s scale.