United States releases an update of its plutonium inventory

The United States released a report The United States Plutonium Balance, 1944-2009," which updated the information about the U.S. plutonium inventory first published in February 1996 in Plutonium: The First 50 Years.

According to the document, as of September 30, 2009:

  • The plutonium inventory, maintained under nuclear material control and accountability, is 95.4 MT, a 4.1 MT (4 %) decrease to the 1994 inventory. The 95.4 MT total includes a combined Pantex and nuclear weapons stockpile of 67.7 MT. The most important factor for the reduction in inventory was the reclassification of process residues originally set aside for plutonium recovery as waste. Of the 4.1 MT reduction, 3.5 MT (85 %) came from Rocky Flats residues sent to WIPP for disposition;
  • The cumulative inventory difference for accountable plutonium is 2.4 MT, a 0.4 MT (14 %) decrease to the 2.8 MT made public in the 1996 plutonium report. The 0.4 MT decrease in the cumulative inventory difference is attributed to materials recovered during de-inventorying and closure activities at Rocky Flats (0.3 MT) and Hanford (0.1 MT). Of the current 2.4 MT of inventory difference, 1.1 MT (46%) is at Hanford and 0.9 MT (38%) at Rocky Flats. A large portion of the remaining 2.4 MT cumulative inventory difference appears to be explained by understated removals from inventory to waste;
  • Plutonium surplus to defense needs is now 43.4 MT, a 5.2 MT (14 %) increase to the 1994 declaration; and
  • The plutonium estimated in waste estimate is 9.7 MT, a 5.8 MT (149%) increase to the 1994 inventory of 3.9 MT. The 5.8 MT increase is attributed to: 4.4 MT (76%) in new discards from the accountable inventory; 0.8 MT (330%) increase in Rocky Flats solid waste generated prior to 1970; 0.4 MT (84%) increase in Hanford high level waste tank estimates; 0.1 MT in solid waste at a commercial low-level radioactive disposal facility not included in the 1996 report, and 0.1 MT from other sites.