DOE OSTI2017
Radioactive materials are self-damaging, which over time, impacts many physical and mechanical properties. One well documented effect is a change in density due to swelling from the accumulated damage to the atomic structure and in the case of α-decay, helium in-growth. In some materials, void growth has been shown to develop, where after a period of incubation, the material swells at a rapid rate, with deleterious effects. A second contrasting effect occurs in Ga stabilized δ-Pu, which is thermodynamically unstable and can partially transform to α’-Pu, a phase 20% denser and thus will cause contraction. Such changes can be observed through several experimental techniques. A change in length, measured by dilatometry is perhaps the simplest to understand, and best characterization of bulk. This report describes the development and testing of a dilatometer capable of measuring length changes resulting from radiation damage in standard weapons grade plutonium over a reasonable time scale (~ 1 month) and the preliminary results of measurements on plutonium samples. The dilatometer has the ability to measure swelling in samples between 0-100°C, a temperature range of programmatic interest.