Preservation and Characterization of X-10 Graphite Reactor Slugs

Irradiated natural uranium slugs from the United States’ first plutonium production pile have been identified for characterization and preservation by the National Nuclear Materials Archive (NNMA). The slugs were irradiated in the 1940s at the X-10 Graphite Reactor at Oak Ridge National Laboratory. The reactor, built after the test pile in Chicago, was the world’s first continuously operating reactor and produced small quantities of plutonium to support the development of chemical separation techniques used later at the Hanford Site. X-10–produced material is similar to material produced at the Hanford Site; original Hanford material is no longer available for analysis. The slugs were shipped to Brookhaven National Laboratory in the 1950s for characterization and moved to Savannah River National Laboratory in 2010, where they have been in storage. The X-10 slugs are believed to represent the oldest irradiated material in the world, and they are certainly representative of the earliest plutonium production in the United States. These slugs are the only known samples remaining from irradiation of natural uranium in a graphite pile and as a predecessor to the Hanford B-Reactor. They represent a unique opportunity to perform a comparative analysis between radiochemical results and predictive modeling, allowing a benchmark test of reactor modeling as a forensics tool. This paper describes the plans to transfer the X-10 slugs from Savannah River National Laboratory to Oak Ridge National Laboratory for characterization and preservation in the NNMA.