Quantifying and Qualifying Alloys Based on Level of Homogenization: A U-10Mo Alloy Case Study

Abstract

Homogenization heat treatment is performed to attain uniformity in microstructure which is helpful to achieve the desired workability and microstructure in final products and, eventually, to gain predictive and consistent performance. Fabrication of low-enriched uranium alloys with 10 wt% molybdenum (U-10Mo) fuel plates involves multiple thermomechanical processing steps. It is well known that the molybdenum homogeneity in the final formed product affects the performance in the nuclear reactor. To ensure uniform homogenization, a statistical method is proposed to quantify and characterize the molybdenum concentration variation in U-10Mo fuel plates by analyzing the molybdenum concentration measurement data from scanning electron microscopy energy dispersive spectroscopy line-scan. Statistical tolerance intervals (TI) are employed to determine the qualification of the U-10Mo fuel plate. We formulate an argument for the minimum number of independent samples to define fuel plate qualification if no molybdenum measurement data are available in advance and demonstrate that the given TI requirements can be equivalently reduced to a sample variance criterion in this application. The outcome of the statistical analysis can be used to optimize casting design and eventually increase productivity and reduce fabrication costs. The statistical strategy developed in this paper can be implemented for other applications especially in the field of material manufacturing to assess qualification requirements and monitor and improve the process design.

Innovation and qualification of LEU research reactor fuels and materials

“…The U.S. Department of Energy's United States High-Performance Research Reactor (USHPRR) Conversion Project has investigated low-enriched uranium (LEU) since 1978 as an alternative to highly enriched uranium. Due to the high loading and good fabrication performance, U-10Mo was chosen as the most promising LEU fuel for the conversion of all USHPRRs [9,[18][19][20][23][24][25][26][27].…”