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 2018.
Japan (INFCIRC/549/Add.1-22) reported owning the total of 45.7 tons of plutonium, 9.0 tons of which is in Japan (the numbers in 2017 were 47.3 tons and 10.6 tons respectively). According to the Status Report on Plutonium Management in Japan - 2018 released in July 2019, out of the 36.7 tons of plutonium abroad, 21.205 tons are in the United Kingdom and 15.460 tons are in France.
Germany (INFCIRC/549/Add.2-22) 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.3-18) 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 2018.
Switzerland (INFCIRC/549/Add.4-23) 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.5-23) reported having 83.2 tons of separated unirradiated plutonium in its custody. Of this amount, 15.5 tons belongs to foreign countries. It appears that all that plutonium - 15,460 kg - belongs to Japan. The amount of plutonium owned by France is 67.7 tons, an increase of 2.3 tonnes from previous year.
The United States (INFCIRC/549/Add.6-22) declared 49.3 tons of separated plutonium, of which 4.6 tons are in MOX fuel and 44.7 tons are "held elsewhere" (most of this material is believed to be in weapon components). This is a decrease of 0.1 tonnes from previous year. According to the document, the United States disposed additional 0.1 tonnes of plutonium as waste (increasing the amount of the material disposed as waste from 4.5 to 4.6 tonnes).
China has not yet submitted its 2018 report (as of 18 December 2019).
The United Kingdom (INFCIRC/549/Add.8-22) reported having 138.9 tonnes of separated plutonium in the country, of which 23.1 tons belonged to foreign bodies (that includes 21.205 tonnes of Japan's plutonium). UK own plutonium stock was 115.8 tons, an increase of 2.7 tons from previous year (113.1 tons).
Russia (INFCIRC/549/Add.9-21) reported owning 61.3 tons of civilian plutonium, an increase of 2.3 tons over the amount held in 2017. This includes 56.5 tons of material in storage, 3.2 tons of plutonium in unirradiated MOX and 0.4 tons of plutonium stored elsewhere. In 2018, Russia for the first time reported that some plutonium, 1.2 tons, is involved in MOX fabrication process.
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, 0.94 tonnes of HEU in irradiated research reactor fuel, and 0.01 tonnes in the category "HEU held elsewhere." The numbers have not changed since 2017.
France declared 5144 kg of HEU (5190 kg in 2017), of which 3654 kg (3264 kg) is unirradiated material - 996 kg (1031 kg) of HEU at fuel fabrication or reprocessing plants, 101 kg (113 kg) at civil reactor sites, 2517 kg (2110 kg) at various research facilities. Also declared are 1536 kg (1593 kg) of irradiated HEU - 91 kg (134 kg) at civil reactor sites and 1439 kg (1402 kg) in other locations.
The United Kingdom reported having 742 kg of HEU (1241 kg in 2017). Of this amount, 1103 kg is unirradiated HEU: 2 kg of unirradiated HEU is stored at the enrichment plants, 170 kg - at fuel fabrication facilities, and 432 kg - at other sites. Irradiated HEU is located at civil reactor sites (5 kg) and other sites (132 kg). The decrease of 499 kg of unirradiated HEU appears to be the result of a program that transferred a total of 700 kg of HEU from the United Kingdom to the United States. The program was completed in May 2019.