Fabrication and evaluation of rare-earth-bearing fuel slugs for sodium-cooled fast reactors

Abstract

Separation of rare-earth (RE) elements from minor actinides is difficult in pyroprocessing, especially for light REs (e.g., Nd, Ce, Pr, and La). Herein, U-10 wt%Zr fuel slugs containing 0, 3, and 7 wt%RE (RE: a rare-earth alloy comprising 53 % Nd, 25 % Ce, 16 % Pr, and 6 % La by weight) were prepared by gravity casting. Their casting soundness was characterized by gamma-ray radiography and immersion density measurement, while their microstructures and compositions were analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Their actual compositions and impurities were confirmed using inductively coupled plasma atomic emission spectrometry. The compatibility of casting components and recovery of radioactive materials were evaluated based on the RE content.