The U.S. Department of Energy’s National Nuclear Security Administration (DOE/NNSA) works to minimize civilian stocks of highly enriched uranium (HEU) and separated plutonium by removing or confirming the disposition of excess weapons-usable nuclear material (WUNM) around the world. To date, DOE/NNSA has removed or confirmed the disposition of more than 7,100 kg of WUNM from 48 countries and Taiwan. Despite this work, large quantities of WUNM are still in civil commerce worldwide, much of which is excess to actual needs and is suitable for elimination. However, a large portion of these inventories is difficult to remove or otherwise disposition due to political, technical, and economic constraints. To overcome these obstacles, DOE/NNSA is developing a mobile platform for stabilizing excess WUNM and converting it into a stable, more proliferation resistant, low-attractiveness wasteform that can be readily disposed in a solid waste disposal facility. This system builds on DOE’s advances in the melt-dilute process originally developed for the treatment aluminum spent fuel materials to produce repository-acceptable waste forms. DOE/NNSA has further adapted this process to cover wide ranging fuel and clad materials and is currently working to stage this process on a mobile platform. The prototype Mobile Melt-Consolidate (MMC) test system leverages the melt processing technology and our understanding of metallurgical phase stability to develop customizable, stable waste forms to meet foreign partners’ solid waste disposal facility performance envelopes. The MMC system aims to provide a new capability to eliminate small quantities of legacy WUNM in-country or in-region rather than commercial transport over long distances. DOE/NNSA estimates that the MMC capability will be able to address approximately 20-50% of the known excess foreign tranches of WUNM. This paper will review the issues and challenges associated with the elimination the diverse types of remaining, legacy WUNM and describe in detail the MMC concept and principles. The paper will also highlight the planned capabilities of the prototype MMC test system and the associated R&D validation and optimization studies. It will also describe the safety analysis and the regulatory framework for its design and operation. Finally, it will present a notional deployment model framework.
Year
2020
Abstract