Belgium submitted to IAEA a declaration of its civilian plutonium holdings as of December 31, 2011 - INFCIRC/549/Add.3/12. According to the document, at the end of 2011 Belgium had no unirradiated separated plutonium stored at reprocessing plants and no separated plutonium held abroad. It declared 500 kg of plutonium in unirradiated MOX fuel - a change from a less than 50 kg in 2010. It also had less than 50 kg of the material in each of the following categories - held up in the fuel fabrication process, and "held elsewhere." These numbers have not changes since the 2010 declaration.

According to the declaration, Belgium has an estimated 35,000 kg of plutonium in irradiated fuel of power reactors, up from 34,000 kg in 2010.