| Abstract Scope |
Uranium nitride (UN) exhibits properties, such as high uranium density and high thermal conductivity, that make it a potential replacement for uranium dioxide (UO<sub>2</sub>) in a range of reactor designs. However, it suffers from room temperature oxidation when finely milled: a step required to reduce the powder particle size which facilitates a high-density fuel pellet after sintering. Even under controlled atmosphere, ageing studies show an increase in oxygen impurities over time, which negatively impact sinterability and final fuel properties. This sensitivity to oxygen as well as pyrophoricity in air imposes strict handling conditions on UN powder. Here, we address relaxing these handling constraints using powder injection molding (PIM). This process utilizes high proportions of polymer binder mixed with the powder to fabricate ceramic compacts. When mixed with UN powder, the polymeric binder acts as a protective barrier to oxidation, reducing oxygen uptake compared to bare powder. Debinding and sintering then produces parts with comparable properties to those made using conventional powder metallurgical methods. Here we show the application of PIM to nuclear fuels. First, for UO<sub>2</sub> to demonstrate initial process optimization and the relation between fabrication conditions and process induced defects, then for UN. Results will show the optimization and characterization of the PIM process for ceramic nuclear fuels as well as comparisons of oxygen uptake under different atmospheric conditions for UN through quantitative oxygen impurity analysis. |