Lessons Learned from Processing Mark-18A Targets at Oak Ridge National Laboratory

The US Department of Energy (DOE) manages an inventory of materials that contains a range of long-lived radioactive isotopes produced from the 1960s through the 1980s by irradiating targets in production reactors at the Savannah River Site (SRS) to produce special heavy isotopes for DOE programmatic use, scientific research, and industrial and medical applications [1]. During the late 1960s, one of the production reactors was configured to operate in a very high flux mode, and >8 kg of 242Pu contained in 86 Mark-18A targets was irradiated to produce 252Cf for use in neutron source applications. Twenty-one targets were processed at Oak Ridge National Laboratory (ORNL) to recover the 252Cf, heavy curium (i.e., curium rich in 246Cm through 248Cm), and 244Pu. Sixty-five of the Mark-18A targets were not processed and are currently in wet storage at SRS. DOE’s Office of Nuclear Materials Integration is establishing a Mark-18A Target Material Recovery Program to separate and preserve the unique materials in these targets. This report summarizes the history of the Mark-18A targets processed at ORNL from 1971 to 1973 to provide background information for development of the dissolution and separations processing flowsheet for recovery of materials from the targets in storage at SRS.