State-of-the-art in Manufacturing Pyrochemical Processing Crucibles

Abstract

Engineers at Los Alamos National Laboratory have been purifying plutonium through pyrochemical processing for many years. The harsh environments involved with the pyrochemical processes include high temperatures (700-900 °C), molten salts and reactive metals (MgCl2, PuCl3, NaCl-KCl, CaCl2, Pu, Ca), and chlorine gas. Because of these corrosive conditions, designing and developing the pyrochemical processing equipment has always been an intriguing technical challenge. In this article I focus on the design and development of the pyrochemical processing crucible for the electrorefining (ER) process, applying design for manufacturability principles throughout the process. I review the current crucible design and electrorefining process and explore possibilities of making the crucible as one part, building the anode and cathode into the crucible, and various material of construction improvements. Materials of construction that should be reviewed further include alumina, silicon nitride, and a tantalum carbon alloy. I briefly review the application of three-dimensional (3D) printing to the process of producing the ER crucible, including thermoplastic 3D printing and mechanical property concerns. I finish by summarizing current plans and possibilities of improving the ER crucible.