This post contains a summary of INFCIRC/549 reports by the countries that submit annual civilian plutonium declarations that reflect the status of civilian plutonium stocks as of 31 December 2017. The post will be updated as more states submit their reports.
Japan (INFCIRC/549/Add.1-21) reported owning the total of 47.3 tons of plutonium, 10.6 tons of which is in Japan (the numbers in 2016 were 47.8 tons and 10.7 tons respectively). According to the Status Report on Plutonium Management in Japan - 2017 released in July 2018, out of the 36.7 tons of plutonium abroad, 21.232 tons are in the United Kingdom and 15.486 tons are in France. Japan is currently working on a new approach to plutonium management.
Germany (INFCIRC/549/Add.2-21) reported having no separated plutonium in the country (0.5 tons in 2016). Germany does not report separated plutonium outside of the country. It is believed to be less than 1 ton.
Belgium (INFCIRC/549/Add.3-17) declared no separated plutonium in storage or at reprocessing plants and "less than 50 kg" of separated plutonium in other categories. It reported that it had no foreign plutonium as of 31 December 2017. Belgium also corrected the 2016 report, stating that it had no foreign plutonium as of 31 December 2016 as well, not "less than 50 kg" as it reported at the time.
Switzerland (INFCIRC/549/Add.4-22/Corr.) reported having less than 2 kg of plutonium in the country (in the "located elsewhere" category). The number has not changed since 2016 (it was "less than 50 kg" in 2015).
France has not yet submitted its 2017 report (as of 19 September 2018).
The United States has not yet submitted its 2017 report (as of 19 September 2018).
China has not yet submitted its 2017 report (as of 19 September 2018).
The United Kingdom has not yet submitted its 2017 report and hasn't yet published its 2017 national report (as of 19 September 2018).
Russia (INFCIRC/549/Add.9-20) reported owning 59.0 tons of civilian plutonium. This includes 56.7 tons of material in storage, 1.8 tons of plutonium in unirradiated MOX and 0.5 tons of plutonium stored elsewhere. The numbers in 2016 were 54.9, 1.7, and 0.6 tons respectively for the total of 57.2 tons.
In addition to reporting plutonium stocks, some countries also submit data on their civilian HEU:
Germany reported 0.32 tonnes of HEU in research reactor fuel (0.33 tons in 2016), 0.94 tonnes of HEU in irradiated research reactor fuel, and 0.01 tonnes in the category "HEU held elsewhere."