PNNL

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 get predictive and consistent performance. Fabrication of low enriched uranium alloys with 10wt% Mo (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 was proposed to quantify and characterize the Mo concentration variation in U-Mo fuel plates by analyzing the Mo concentration measurement data from scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) line scan. The concept of tolerance interval (TI) was for the first time employed to determine the qualification of U-10Mo fuel plate. We also propose the minimum number of required samples to define fuel plate qualification if no Mo measurement data is available in advance. We demonstrated that the given TI requirements can be equivalently reduced to confine the samples variance. This simpler criteria provides easy-to-understand guidance to evaluate fuel plate quality. The outcome of the statistical analysis can be used to optimize casting design and eventually increase productivity and reduce fabrication cost. 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 process design.