Preparation of TEM Specimens From Highly Radioactive Materials

Abstract

Intense radioactivity from nuclear materials such as irradiated UO2 and high-level waste glass often makes it impractical to prepare specimens of these materials for transmission electron microscopy. This paper describes a technique that yields ion-milled TEM specimens of reasonably low total activity from highly radioactive materials. Finished specimens each consist of a 3 mm diameter annular support ring that contains a small particle of sample, typically 50 to 300 μm in diameter and 5 to 10 μm in thickness, in epoxy. Although the application to nuclear materials is highly specialized, the basic preparation method requires only readily obtained materials, the simple grinding jig shown in Fig. 1 and an ion micromill for final specimen thinning.The specimen preparation procedure is as follows: A 3 mm diameter washer, 0.15 mm in thickness with a 0.5 mm central hole, is placed over a 50 to 300 μm diameter particle on Parafilnn and the resulting well containing the particle is filled with epoxy.