DOE-ARN Method to Verify Uranium Inventory at the Pilcaniyeu Gaseous Diffusion Enrichment Plant

The Pilcaniyeu Gaseous Diffusion Plant is located near San Carlos de Bariloche, Argentina, in the Province of Rio Negro. It is designed to enrich uranium to a nominal level of 5% 235 U, and a nominal capacity of 20,000 separate work units per year. Since 1003, this facility has been under international safeguards. New measurement methods were required to accurately verify Pilcaniyeu's uranium inventory, because this is the first gaseous diffusion enrichment plant to come under International Atomic Energy Agency (IAEA) safeguards. In 1992, the United States and Argentina embarked on a cooperative effort to accomplish this task. Several nondestructive measurement experiments were performed at gaseous diffusion plants in the United States and at the Pilcaniyeu plant in Argentina. It was determined that passive gamma-ray measurement is the technique of choice for Pilcaniyeu . Mathematically algorithms were developed that accurately estimate the uranium inventory of the facility. This paper summarizes the measurement activities conducted under Argentine-U.S. cooperation, discusses the proposed methods, and proposes a process to validate the procedure for IAEA use.