NNSA is responsible for disposing of U.S. highly enriched uranium (HEU) that has been declared surplus to defense needs primarily by down-blending, or converting, it into low enriched uranium (LEU). Once down-blended, the material can no longer be used for nuclear weapons. To the extent practical, NNSA seeks to recover the economic value of the material by using the resulting LEU as nuclear reactor fuel.

U.S.-Russian Highly Enriched Uranium Purchase Agreement
NNSA’s HEU Transparency Program monitors the conversion of surplus HEU from Russian nuclear weapons into LEU used as fuel in U.S. commercial power reactors.   NNSA monitors the elimination of 30 metric tons of Russian HEU annually, the equivalent of about 1,200 nuclear weapons.  By the time the HEU Purchase Agreement is completed in 2013, NNSA will have confirmed that 500 metric tons of HEU, equivalent to about 20,000 nuclear weapons, has been permanently eliminated from the Russian stockpile.  Eliminating this vast quantity of weapons-usable HEU reduces nuclear risk by ensuring that this material can never be stolen or diverted for use in a crude nuclear weapon.