Development of and initial assessment of microstructurally engineered UN
Fuels with high uranium densities have been considered in the Nuclear Technology Research and Development program’s Advanced Fuels Campaign as potential replacements for uranium(IV) oxide in commercial light water reactors. One such candidate fuel is uranium mononitride, UN, which has been observed to readily oxidize in steam and simulated pressurized water reactor conditions. Thus, it is important to examine methods for waterproofing UN, especially for potential cladding breach scenarios. This can be achieved by controlling the microstructure so as to prevent contact between the UN fuel and coolant. Research so far this FY has focused on screening potential candidate additive materials to control UN microstructure using steam oxidation TGA. From these candidates, yttrium was selected based on corrosion resistance, which led to attempts to develop a method for liquid phase sintering of yttrium with UN. Yttrium in the form of yttrium dihydride (YH2) was mixed with UN, pressed, and heated to temperatures above the melting point of Y metal to dehydride the material and then melt it to enable liquid phase sintering. Results showed no indication of densification, but did show chemical interaction between Y and UN, resulting in the formation of yttrium nitride (YN) and uranium metal. These observations were used to develop a better understanding of microstructure control for UN waterproofing to be addressed in an L2 milestone that is an FY19 deliverable (M2FT-19LA020201021).
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- DOE Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1544659
- Report Number(s):
- LA-UR-19-22533
- Country of Publication:
- United States
- Language:
- English
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