Effects of Pu Decay on a Sodalite Based Ceramic Waste Form

Abstract

Radiation damage from the decay of actinide containing phases in ceramic waste forms can reduce their mechanical integrity and chemical durability. In order to understand the radiation damage and predict long-term degradation behavior of the ceramic waste forms in a repository, a short-lived actinide can be loaded into the ceramic waste form to accelerate the damage process. In the current study, a 238Pu (half-life of 87.7 years) doped ceramic waste form was fabricated by uniaxial hot pressing. The starting materials are 75 volume percent salt occluded zeolite and 25 volume percent binding glass. After consolidation, the final product has sodalite and glass as the major constituents, while halite, nepheline and actinide containing phases are minor phases. After three years, density measurements, scanning electron microscopy, and seven-day product consistency tests all reveal little or no change. Bubbles/voids have been found by transmission electron microscopy. No defect-segregation was observed. Although X-ray diffraction shows a very small unit cell expansion in PuO2 and sodalite, micro-cracking and interface debonding were not observed. Preliminary results show that the electron beam dose required to amorphize sodalite decreases with increasing alpha decay dose.