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 2020.
Japan (INFCIRC/549/Add.1-24) reported owning the total of 46.1 tons of plutonium, 8.9 tons of which is in Japan (the numbers in 2019 were 45.5 tons and 8.9 tons respectively). According to the Status Report on Plutonium Management in Japan - 2020 released in July 2021, out of the 37.2 tons of plutonium abroad, 21.805 tons are in the United Kingdom and 15.411 tons are in France.
Germany (INFCIRC/549/Add.2-24) reported having no separated plutonium in the country for the second year in a row. Germany does not report separated plutonium outside of the country. It is believed to be less than 1 ton.
Belgium (INFCIRC/549/Add.3-20) declared no separated plutonium in storage or at reprocessing plants and "not zero, but less than 50 kg" of separated plutonium in other categories. It reported that it had no foreign plutonium as of 31 December 2020.
Switzerland (INFCIRC/549/Add.4-25) 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 (INFCIRC/549/Add.5-25) reported having 95.0 tons of separated unirradiated plutonium in its custody. Of this amount, 15.6 tons belongs to foreign countries. It appears that almost all that plutonium - 15,411 kg - belongs to Japan. The amount of plutonium owned by France is 79.5 tons, an increase of 4.8 tonnes from previous year (74.7 tons).
The United States has not submitted its 2019 report. In its 2020 report (INFCIRC/549/Add.6-23) declared 49.4 tons of separated plutonium, of which 4.6 tons are in MOX fuel and 44.8 tons are "held elsewhere" (most of this material is believed to be in weapon components). This amount was reported to be 44.7 tons in 2018, but went back to 44.8 tons in 2019 (as indicated by the "previous year" number in the 2020 declaration). These changes appear to reflect changes in the accounting for the material - the amount reported as "disposed as waste" was 4.6 tons in 2018, but was reverted to 4.5 tons in 2020.
China has not has not submitted its 2017-2020 reports as of 24 October 2021. The last INFCIRC/549 report submitted to the IAEA showed 40.9 kg of separated plutonium as of 31 December 2016.
The United Kingdom (INFCIRC/549/Add.8-24) reported owning 116.1 tons of separated plutonium, an increase from 115.8 in 2018 (most likely the result of taking title of already separated Japan's plutonium). In addition to that, the United Kingdom stores 24.1 tons of foreign plutonium (of which 21.805 tons is owned by Japan).
Russia has not submitted its 2020 report as of 24 October 2021.
In addition to reporting plutonium stocks, some countries also submit data on their civilian HEU:
Germany reported 0.35 tonnes of HEU in research reactor fuel (an increase from 0.32 tonnes in 2019), 0.94 tonnes of HEU in irradiated research reactor fuel, and 0.01 tonnes in the category "HEU held elsewhere" (unchanged).
France declared 5319 kg of HEU (5373 kg in 2019), of which 3785 kg (3836 kg) is unirradiated material - 852 kg (930 kg) of HEU at fuel fabrication or reprocessing plants, 74 kg (51 kg) at civil reactor sites, 2859 kg (2855 kg) at various research facilities. Also declared are 1533 kg (1537 kg) of irradiated HEU - 79 kg (99 kg) at civil reactor sites and 1454 kg (1438 kg) in other locations.
The United Kingdom reported having 738 kg of HEU (734 kg in 2019). Of this amount, 601 kg is unirradiated HEU (598 in 2019): less than 1 kg of unirradiated HEU is stored at the enrichment plants, less than 1 kg is at civil reactor sites, 421 kg - at fuel fabrication facilities, and 180 kg - at other sites (417 kg and 181 kg respectively in 2019). Irradiated HEU is located at civil reactor sites (5 kg) and other sites (132 kg).