A method is described for preparing plaster of Paris replicas of irradiated fuel slugs. An impression mold is made by pouring the plaster about a fuel slug held in a specially designed holder. The slug is removed from the holder and the impression mold issued to cast a replica, also made of plaster of Paris. The replicas, including one end only, are accurate reproduction of the original slug for surface features down to about one-half mil and for dimensions within one or two mills. Two dental impression plasters were found to give satisfactory results. With the limits mentioned, the process will serve the purpose of preserving models of radioactive specimens for use as "museum pieces." However, the procedures are very exacting in achieving such results.