This NATO Advanced Research Workshop on Disposal of Weapons Plutonium is a follow-up event to two preceding workshops, each dealing with a special subject within the overall disarmament issue: "Disposition of Weapon Plutonium", sponsored by the NATO Science Committee. The first workshop of this series was held at the Royal Institute of International Affairs in London on 24-25 January 1994, entitled "Managing the Plutonium Surplus, Applications, and Options". Its over­ all goal was to clarify the current situation with respect to pluto­ nium characteristics and availability, the technical options for use or disposal, and their main technical, environmental, and economic constraints. In the immediate term, plutonium recovered from dismantled nuclear warheads will have to be stored securely, and under international safeguards if possible. In the intermediate term, the principal alter­ natives for disposition of this plutonium are: irradiation in mixed­ oxide (MOX) fuel assemblies in existing commercial light-water reac­ tors or in specially adapted light-water reactors capable of operation with full cores of MOX fuel .and irradiation in future fast reactors. Another option is to blend plutonium with high-level waste as it is vitrified for final disposal in a geologic repository. In both cases, the high radioactivity of the resulting products provides "self­ shielding" and prevents separation of plutonium without already­ developed and available sophisticated technology. The so-called "spent fuel standard" as an effective protection barrier is - quired in either case.