The Vault at the Plutonium Finishing Plan (PFP) became subject to the International Atomic Energy Agency (IAEA) safeguards beginning in 1994 as part of the US excess fissile material program. The inventory needed to be stabilized and repackaged for long-term storage to comply with Defense Nuclear Facilities Safety Board Recommendation 94-1. In 1998, the United States began negotiations with IAEA to develop methods to maintain safeguards as this material was stabilized and repackaged. The Design Information Questionnaire was revised and submitted to the IAEA in 2002 describing how PFP would be modified to accommodate the stabilization process line. The operation plan for 2003 was submitted describing the proposed schedules for removing materials for stabilization. Stabilization and repackaging activities for the safeguarded plutonium began in January 2003 and were completed in December 2003. The safeguards approach implemented at the Hanford Site was a combination of the original baseline approach augmented by a series of five vault additions of stabilized materials followed by five removals of unstabilized materials.