Accelerated alpha radiation damage in a ceramic waste form, interim results

Interim results are presented on the alpha-decay damage study of a ²³⁸Pu-loaded ceramic waste form (CWF). The waste form was developed to immobilize fission products and transuranic species accumulated from the electrometallurgical treatment of spent nuclear fuel. To evaluate the effects of α-decay damage on the waste form, the ²³⁸Pu-loaded material was investigated by electron microscopy for microstructure characterization, x-ray diffraction for bulk phase properties, bulk density measurement, and the product consistency test (PCT) for waste form durability. While the predominate phase of plutonium in the CWF, PuO₂, shows the expected unit cell expansion due to α-decay damage, currently no significant change has occurred to the macro- or microstructure of the material. The major phase of the waste form is sodalite and contains very little Pu, although the exact amount is unknown. Interestingly, measurement of the sodalite phase unit cell is also showing very slight expansion; again, presumably from α-decay damage.