The United States submitted a declaration of its civilian plutonium stock as of the end of 2011 - INFCIRC/549/Add.6/15. According to the declaration, the United States had 44.7 tonnes of separated plutonium described as "held elsewhere", 4.6 tonnes - in unirradiated MOX fuel, and less than 0.05 tonnes - held in the fuel fabrication process. In 2010 these numbers were 49.3, 4.6, and 0.05 tonnes respectively.
The Unites States also has an estimated 564 tonnes of plutonium in spent fuel stored at civilian reactor sites and 12 tonnes of plutonium in spent fuel elsewhere. In 2010 these numbers were 542 and 12 tonnes respectively.
The note contains the following comment:
Lines 3 [44.7 tonnes] and 4 [4.6 tonnes] together list 49.3 metric tons of separated plutonium that has been declared as excess to national security needs. This, in addition to 7.8 metric tons of the plutonium included on lines 1 [564 tonnes] and 3 [12 tonnes] of Annex C and 4.4 metric tons that has been disposed to waste after termination of safeguards post-1998, constitute the total of 61.5 metric tons of government owned plutonium that the United States has declared as excess to national security needs.