The United States and Japan announced today that they will remove all plutonium and HEU from the Fast Critical Assembly (FCA) in JAERI Tokai Research Establishment. The agreement to remove the plutonium was first made public in January 2014. The agreement announced today includes removal of HEU as well. According to the U.S. official statement:

[Plutonium and HEU], once securely transported to the United States, will be sent to a secure facility and fully converted into less sensitive forms. The plutonium will be prepared for final disposition. The HEU will be downblended to low enriched uranium (LEU) and utilized for civilian purposes.

The Fast Critical Assembly uses 331 kg of plutonium (see the January 27, 2014 post). According to the Japan Atomic Energy Agency, this material was supplied by three states - the United Kingdom (236 kg), the United States (93 kg) and France (2 kg). The total amount of fissile plutonium in that material is 293 kg.